crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.357 2017/02/01 02:59:09 dtucker Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/stat.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/un.h>
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_TIME_H
  50 # include <sys/time.h>
  51 #endif
  52
  53 #include <netinet/in.h>
  54 #include <arpa/inet.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #ifdef HAVE_STDINT_H
  60 #include <stdint.h>
  61 #endif
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <termios.h>
  66 #include <unistd.h>
  67 #include <stdarg.h>
  68
  69 #include "openbsd-compat/sys-queue.h"
  70 #include "xmalloc.h"
  71 #include "ssh.h"
  72 #include "ssh1.h"
  73 #include "ssh2.h"
  74 #include "ssherr.h"
  75 #include "packet.h"
  76 #include "log.h"
  77 #include "misc.h"
  78 #include "buffer.h"
  79 #include "channels.h"
  80 #include "compat.h"
  81 #include "canohost.h"
  82 #include "key.h"
  83 #include "authfd.h"
  84 #include "pathnames.h"
  85
  86 /* -- channel core */
  87
  88 /*
  89  * Pointer to an array containing all allocated channels.  The array is
  90  * dynamically extended as needed.
  91  */
  92 static Channel **channels = NULL;
  93
  94 /*
  95  * Size of the channel array.  All slots of the array must always be
  96  * initialized (at least the type field); unused slots set to NULL
  97  */
  98 static u_int channels_alloc = 0;
  99
 100 /*
 101  * Maximum file descriptor value used in any of the channels.  This is
 102  * updated in channel_new.
 103  */
 104 static int channel_max_fd = 0;
 105
 106
 107 /* -- tcp forwarding */
 108
 109 /*
 110  * Data structure for storing which hosts are permitted for forward requests.
 111  * The local sides of any remote forwards are stored in this array to prevent
 112  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 113  * network (which might be behind a firewall).
 114  */
 115 /* XXX: streamlocal wants a path instead of host:port */
 116 /*      Overload host_to_connect; we could just make this match Forward */
 117 /*      XXX - can we use listen_host instead of listen_path? */
 118 typedef struct {
 119         char *host_to_connect;          /* Connect to 'host'. */
 120         int port_to_connect;            /* Connect to 'port'. */
 121         char *listen_host;              /* Remote side should listen address. */
 122         char *listen_path;              /* Remote side should listen path. */
 123         int listen_port;                /* Remote side should listen port. */
 124         Channel *downstream;            /* Downstream mux*/
 125 } ForwardPermission;
 126
 127 /* List of all permitted host/port pairs to connect by the user. */
 128 static ForwardPermission *permitted_opens = NULL;
 129
 130 /* List of all permitted host/port pairs to connect by the admin. */
 131 static ForwardPermission *permitted_adm_opens = NULL;
 132
 133 /* Number of permitted host/port pairs in the array permitted by the user. */
 134 static int num_permitted_opens = 0;
 135
 136 /* Number of permitted host/port pair in the array permitted by the admin. */
 137 static int num_adm_permitted_opens = 0;
 138
 139 /* special-case port number meaning allow any port */
 140 #define FWD_PERMIT_ANY_PORT     0
 141
 142 /* special-case wildcard meaning allow any host */
 143 #define FWD_PERMIT_ANY_HOST     "*"
 144
 145 /*
 146  * If this is true, all opens are permitted.  This is the case on the server
 147  * on which we have to trust the client anyway, and the user could do
 148  * anything after logging in anyway.
 149  */
 150 static int all_opens_permitted = 0;
 151
 152
 153 /* -- X11 forwarding */
 154
 155 /* Maximum number of fake X11 displays to try. */
 156 #define MAX_DISPLAYS  1000
 157
 158 /* Saved X11 local (client) display. */
 159 static char *x11_saved_display = NULL;
 160
 161 /* Saved X11 authentication protocol name. */
 162 static char *x11_saved_proto = NULL;
 163
 164 /* Saved X11 authentication data.  This is the real data. */
 165 static char *x11_saved_data = NULL;
 166 static u_int x11_saved_data_len = 0;
 167
 168 /* Deadline after which all X11 connections are refused */
 169 static u_int x11_refuse_time;
 170
 171 /*
 172  * Fake X11 authentication data.  This is what the server will be sending us;
 173  * we should replace any occurrences of this by the real data.
 174  */
 175 static u_char *x11_fake_data = NULL;
 176 static u_int x11_fake_data_len;
 177
 178
 179 /* -- agent forwarding */
 180
 181 #define NUM_SOCKS       10
 182
 183 /* AF_UNSPEC or AF_INET or AF_INET6 */
 184 static int IPv4or6 = AF_UNSPEC;
 185
 186 /* helper */
 187 static void port_open_helper(Channel *c, char *rtype);
 188 static const char *channel_rfwd_bind_host(const char *listen_host);
 189
 190 /* non-blocking connect helpers */
 191 static int connect_next(struct channel_connect *);
 192 static void channel_connect_ctx_free(struct channel_connect *);
 193
 194 /* -- channel core */
 195
 196 Channel *
 197 channel_by_id(int id)
 198 {
 199         Channel *c;
 200
 201         if (id < 0 || (u_int)id >= channels_alloc) {
 202                 logit("channel_by_id: %d: bad id", id);
 203                 return NULL;
 204         }
 205         c = channels[id];
 206         if (c == NULL) {
 207                 logit("channel_by_id: %d: bad id: channel free", id);
 208                 return NULL;
 209         }
 210         return c;
 211 }
 212
 213 Channel *
 214 channel_by_remote_id(int remote_id)
 215 {
 216         Channel *c;
 217         u_int i;
 218
 219         for (i = 0; i < channels_alloc; i++) {
 220                 c = channels[i];
 221                 if (c != NULL && c->remote_id == remote_id)
 222                         return c;
 223         }
 224         return NULL;
 225 }
 226
 227 /*
 228  * Returns the channel if it is allowed to receive protocol messages.
 229  * Private channels, like listening sockets, may not receive messages.
 230  */
 231 Channel *
 232 channel_lookup(int id)
 233 {
 234         Channel *c;
 235
 236         if ((c = channel_by_id(id)) == NULL)
 237                 return (NULL);
 238
 239         switch (c->type) {
 240         case SSH_CHANNEL_X11_OPEN:
 241         case SSH_CHANNEL_LARVAL:
 242         case SSH_CHANNEL_CONNECTING:
 243         case SSH_CHANNEL_DYNAMIC:
 244         case SSH_CHANNEL_OPENING:
 245         case SSH_CHANNEL_OPEN:
 246         case SSH_CHANNEL_INPUT_DRAINING:
 247         case SSH_CHANNEL_OUTPUT_DRAINING:
 248         case SSH_CHANNEL_ABANDONED:
 249         case SSH_CHANNEL_MUX_PROXY:
 250                 return (c);
 251         }
 252         logit("Non-public channel %d, type %d.", id, c->type);
 253         return (NULL);
 254 }
 255
 256 /*
 257  * Register filedescriptors for a channel, used when allocating a channel or
 258  * when the channel consumer/producer is ready, e.g. shell exec'd
 259  */
 260 static void
 261 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 262     int extusage, int nonblock, int is_tty)
 263 {
 264         /* Update the maximum file descriptor value. */
 265         channel_max_fd = MAXIMUM(channel_max_fd, rfd);
 266         channel_max_fd = MAXIMUM(channel_max_fd, wfd);
 267         channel_max_fd = MAXIMUM(channel_max_fd, efd);
 268
 269         if (rfd != -1)
 270                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 271         if (wfd != -1 && wfd != rfd)
 272                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 273         if (efd != -1 && efd != rfd && efd != wfd)
 274                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 275
 276         c->rfd = rfd;
 277         c->wfd = wfd;
 278         c->sock = (rfd == wfd) ? rfd : -1;
 279         c->efd = efd;
 280         c->extended_usage = extusage;
 281
 282         if ((c->isatty = is_tty) != 0)
 283                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 284 #ifdef _AIX
 285         /* XXX: Later AIX versions can't push as much data to tty */
 286         c->wfd_isatty = is_tty || isatty(c->wfd);
 287 #endif
 288
 289         /* enable nonblocking mode */
 290         if (nonblock) {
 291                 if (rfd != -1)
 292                         set_nonblock(rfd);
 293                 if (wfd != -1)
 294                         set_nonblock(wfd);
 295                 if (efd != -1)
 296                         set_nonblock(efd);
 297         }
 298 }
 299
 300 /*
 301  * Allocate a new channel object and set its type and socket. This will cause
 302  * remote_name to be freed.
 303  */
 304 Channel *
 305 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 306     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 307 {
 308         int found;
 309         u_int i;
 310         Channel *c;
 311
 312         /* Do initial allocation if this is the first call. */
 313         if (channels_alloc == 0) {
 314                 channels_alloc = 10;
 315                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 316                 for (i = 0; i < channels_alloc; i++)
 317                         channels[i] = NULL;
 318         }
 319         /* Try to find a free slot where to put the new channel. */
 320         for (found = -1, i = 0; i < channels_alloc; i++)
 321                 if (channels[i] == NULL) {
 322                         /* Found a free slot. */
 323                         found = (int)i;
 324                         break;
 325                 }
 326         if (found < 0) {
 327                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 328                 found = channels_alloc;
 329                 if (channels_alloc > 10000)
 330                         fatal("channel_new: internal error: channels_alloc %d "
 331                             "too big.", channels_alloc);
 332                 channels = xreallocarray(channels, channels_alloc + 10,
 333                     sizeof(Channel *));
 334                 channels_alloc += 10;
 335                 debug2("channel: expanding %d", channels_alloc);
 336                 for (i = found; i < channels_alloc; i++)
 337                         channels[i] = NULL;
 338         }
 339         /* Initialize and return new channel. */
 340         c = channels[found] = xcalloc(1, sizeof(Channel));
 341         buffer_init(&c->input);
 342         buffer_init(&c->output);
 343         buffer_init(&c->extended);
 344         c->path = NULL;
 345         c->listening_addr = NULL;
 346         c->listening_port = 0;
 347         c->ostate = CHAN_OUTPUT_OPEN;
 348         c->istate = CHAN_INPUT_OPEN;
 349         c->flags = 0;
 350         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 351         c->notbefore = 0;
 352         c->self = found;
 353         c->type = type;
 354         c->ctype = ctype;
 355         c->local_window = window;
 356         c->local_window_max = window;
 357         c->local_consumed = 0;
 358         c->local_maxpacket = maxpack;
 359         c->remote_id = -1;
 360         c->remote_name = xstrdup(remote_name);
 361         c->remote_window = 0;
 362         c->remote_maxpacket = 0;
 363         c->force_drain = 0;
 364         c->single_connection = 0;
 365         c->detach_user = NULL;
 366         c->detach_close = 0;
 367         c->open_confirm = NULL;
 368         c->open_confirm_ctx = NULL;
 369         c->input_filter = NULL;
 370         c->output_filter = NULL;
 371         c->filter_ctx = NULL;
 372         c->filter_cleanup = NULL;
 373         c->ctl_chan = -1;
 374         c->mux_rcb = NULL;
 375         c->mux_ctx = NULL;
 376         c->mux_pause = 0;
 377         c->delayed = 1;         /* prevent call to channel_post handler */
 378         TAILQ_INIT(&c->status_confirms);
 379         debug("channel %d: new [%s]", found, remote_name);
 380         return c;
 381 }
 382
 383 static int
 384 channel_find_maxfd(void)
 385 {
 386         u_int i;
 387         int max = 0;
 388         Channel *c;
 389
 390         for (i = 0; i < channels_alloc; i++) {
 391                 c = channels[i];
 392                 if (c != NULL) {
 393                         max = MAXIMUM(max, c->rfd);
 394                         max = MAXIMUM(max, c->wfd);
 395                         max = MAXIMUM(max, c->efd);
 396                 }
 397         }
 398         return max;
 399 }
 400
 401 int
 402 channel_close_fd(int *fdp)
 403 {
 404         int ret = 0, fd = *fdp;
 405
 406         if (fd != -1) {
 407                 ret = close(fd);
 408                 *fdp = -1;
 409                 if (fd == channel_max_fd)
 410                         channel_max_fd = channel_find_maxfd();
 411         }
 412         return ret;
 413 }
 414
 415 /* Close all channel fd/socket. */
 416 static void
 417 channel_close_fds(Channel *c)
 418 {
 419         channel_close_fd(&c->sock);
 420         channel_close_fd(&c->rfd);
 421         channel_close_fd(&c->wfd);
 422         channel_close_fd(&c->efd);
 423 }
 424
 425 /* Free the channel and close its fd/socket. */
 426 void
 427 channel_free(Channel *c)
 428 {
 429         char *s;
 430         u_int i, n;
 431         Channel *other;
 432         struct channel_confirm *cc;
 433
 434         for (n = 0, i = 0; i < channels_alloc; i++) {
 435                 if ((other = channels[i]) != NULL) {
 436                         n++;
 437
 438                         /* detach from mux client and prepare for closing */
 439                         if (c->type == SSH_CHANNEL_MUX_CLIENT &&
 440                             other->type == SSH_CHANNEL_MUX_PROXY &&
 441                             other->mux_ctx == c) {
 442                                 other->mux_ctx = NULL;
 443                                 other->type = SSH_CHANNEL_OPEN;
 444                                 other->istate = CHAN_INPUT_CLOSED;
 445                                 other->ostate = CHAN_OUTPUT_CLOSED;
 446                         }
 447                 }
 448         }
 449         debug("channel %d: free: %s, nchannels %u", c->self,
 450             c->remote_name ? c->remote_name : "???", n);
 451
 452         /* XXX more MUX cleanup: remove remote forwardings */
 453         if (c->type == SSH_CHANNEL_MUX_CLIENT) {
 454                 for (i = 0; i < (u_int)num_permitted_opens; i++) {
 455                         if (permitted_opens[i].downstream != c)
 456                                 continue;
 457                         /* cancel on the server, since mux client is gone */
 458                         debug("channel %d: cleanup remote forward for %s:%u",
 459                             c->self,
 460                             permitted_opens[i].listen_host,
 461                             permitted_opens[i].listen_port);
 462                         packet_start(SSH2_MSG_GLOBAL_REQUEST);
 463                         packet_put_cstring("cancel-tcpip-forward");
 464                         packet_put_char(0);
 465                         packet_put_cstring(channel_rfwd_bind_host(
 466                             permitted_opens[i].listen_host));
 467                         packet_put_int(permitted_opens[i].listen_port);
 468                         packet_send();
 469                         /* unregister */
 470                         permitted_opens[i].listen_port = 0;
 471                         permitted_opens[i].port_to_connect = 0;
 472                         free(permitted_opens[i].host_to_connect);
 473                         permitted_opens[i].host_to_connect = NULL;
 474                         free(permitted_opens[i].listen_host);
 475                         permitted_opens[i].listen_host = NULL;
 476                         permitted_opens[i].listen_path = NULL;
 477                         permitted_opens[i].downstream = NULL;
 478                 }
 479         }
 480
 481         s = channel_open_message();
 482         debug3("channel %d: status: %s", c->self, s);
 483         free(s);
 484
 485         if (c->sock != -1)
 486                 shutdown(c->sock, SHUT_RDWR);
 487         channel_close_fds(c);
 488         buffer_free(&c->input);
 489         buffer_free(&c->output);
 490         buffer_free(&c->extended);
 491         free(c->remote_name);
 492         c->remote_name = NULL;
 493         free(c->path);
 494         c->path = NULL;
 495         free(c->listening_addr);
 496         c->listening_addr = NULL;
 497         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 498                 if (cc->abandon_cb != NULL)
 499                         cc->abandon_cb(c, cc->ctx);
 500                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 501                 explicit_bzero(cc, sizeof(*cc));
 502                 free(cc);
 503         }
 504         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 505                 c->filter_cleanup(c->self, c->filter_ctx);
 506         channels[c->self] = NULL;
 507         free(c);
 508 }
 509
 510 void
 511 channel_free_all(void)
 512 {
 513         u_int i;
 514
 515         for (i = 0; i < channels_alloc; i++)
 516                 if (channels[i] != NULL)
 517                         channel_free(channels[i]);
 518 }
 519
 520 /*
 521  * Closes the sockets/fds of all channels.  This is used to close extra file
 522  * descriptors after a fork.
 523  */
 524 void
 525 channel_close_all(void)
 526 {
 527         u_int i;
 528
 529         for (i = 0; i < channels_alloc; i++)
 530                 if (channels[i] != NULL)
 531                         channel_close_fds(channels[i]);
 532 }
 533
 534 /*
 535  * Stop listening to channels.
 536  */
 537 void
 538 channel_stop_listening(void)
 539 {
 540         u_int i;
 541         Channel *c;
 542
 543         for (i = 0; i < channels_alloc; i++) {
 544                 c = channels[i];
 545                 if (c != NULL) {
 546                         switch (c->type) {
 547                         case SSH_CHANNEL_AUTH_SOCKET:
 548                         case SSH_CHANNEL_PORT_LISTENER:
 549                         case SSH_CHANNEL_RPORT_LISTENER:
 550                         case SSH_CHANNEL_X11_LISTENER:
 551                         case SSH_CHANNEL_UNIX_LISTENER:
 552                         case SSH_CHANNEL_RUNIX_LISTENER:
 553                                 channel_close_fd(&c->sock);
 554                                 channel_free(c);
 555                                 break;
 556                         }
 557                 }
 558         }
 559 }
 560
 561 /*
 562  * Returns true if no channel has too much buffered data, and false if one or
 563  * more channel is overfull.
 564  */
 565 int
 566 channel_not_very_much_buffered_data(void)
 567 {
 568         u_int i;
 569         Channel *c;
 570
 571         for (i = 0; i < channels_alloc; i++) {
 572                 c = channels[i];
 573                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 574 #if 0
 575                         if (!compat20 &&
 576                             buffer_len(&c->input) > packet_get_maxsize()) {
 577                                 debug2("channel %d: big input buffer %d",
 578                                     c->self, buffer_len(&c->input));
 579                                 return 0;
 580                         }
 581 #endif
 582                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 583                                 debug2("channel %d: big output buffer %u > %u",
 584                                     c->self, buffer_len(&c->output),
 585                                     packet_get_maxsize());
 586                                 return 0;
 587                         }
 588                 }
 589         }
 590         return 1;
 591 }
 592
 593 /* Returns true if any channel is still open. */
 594 int
 595 channel_still_open(void)
 596 {
 597         u_int i;
 598         Channel *c;
 599
 600         for (i = 0; i < channels_alloc; i++) {
 601                 c = channels[i];
 602                 if (c == NULL)
 603                         continue;
 604                 switch (c->type) {
 605                 case SSH_CHANNEL_X11_LISTENER:
 606                 case SSH_CHANNEL_PORT_LISTENER:
 607                 case SSH_CHANNEL_RPORT_LISTENER:
 608                 case SSH_CHANNEL_MUX_LISTENER:
 609                 case SSH_CHANNEL_CLOSED:
 610                 case SSH_CHANNEL_AUTH_SOCKET:
 611                 case SSH_CHANNEL_DYNAMIC:
 612                 case SSH_CHANNEL_CONNECTING:
 613                 case SSH_CHANNEL_ZOMBIE:
 614                 case SSH_CHANNEL_ABANDONED:
 615                 case SSH_CHANNEL_UNIX_LISTENER:
 616                 case SSH_CHANNEL_RUNIX_LISTENER:
 617                         continue;
 618                 case SSH_CHANNEL_LARVAL:
 619                         if (!compat20)
 620                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 621                         continue;
 622                 case SSH_CHANNEL_OPENING:
 623                 case SSH_CHANNEL_OPEN:
 624                 case SSH_CHANNEL_X11_OPEN:
 625                 case SSH_CHANNEL_MUX_CLIENT:
 626                 case SSH_CHANNEL_MUX_PROXY:
 627                         return 1;
 628                 case SSH_CHANNEL_INPUT_DRAINING:
 629                 case SSH_CHANNEL_OUTPUT_DRAINING:
 630                         if (!compat13)
 631                                 fatal("cannot happen: OUT_DRAIN");
 632                         return 1;
 633                 default:
 634                         fatal("channel_still_open: bad channel type %d", c->type);
 635                         /* NOTREACHED */
 636                 }
 637         }
 638         return 0;
 639 }
 640
 641 /* Returns the id of an open channel suitable for keepaliving */
 642 int
 643 channel_find_open(void)
 644 {
 645         u_int i;
 646         Channel *c;
 647
 648         for (i = 0; i < channels_alloc; i++) {
 649                 c = channels[i];
 650                 if (c == NULL || c->remote_id < 0)
 651                         continue;
 652                 switch (c->type) {
 653                 case SSH_CHANNEL_CLOSED:
 654                 case SSH_CHANNEL_DYNAMIC:
 655                 case SSH_CHANNEL_X11_LISTENER:
 656                 case SSH_CHANNEL_PORT_LISTENER:
 657                 case SSH_CHANNEL_RPORT_LISTENER:
 658                 case SSH_CHANNEL_MUX_LISTENER:
 659                 case SSH_CHANNEL_MUX_CLIENT:
 660                 case SSH_CHANNEL_MUX_PROXY:
 661                 case SSH_CHANNEL_OPENING:
 662                 case SSH_CHANNEL_CONNECTING:
 663                 case SSH_CHANNEL_ZOMBIE:
 664                 case SSH_CHANNEL_ABANDONED:
 665                 case SSH_CHANNEL_UNIX_LISTENER:
 666                 case SSH_CHANNEL_RUNIX_LISTENER:
 667                         continue;
 668                 case SSH_CHANNEL_LARVAL:
 669                 case SSH_CHANNEL_AUTH_SOCKET:
 670                 case SSH_CHANNEL_OPEN:
 671                 case SSH_CHANNEL_X11_OPEN:
 672                         return i;
 673                 case SSH_CHANNEL_INPUT_DRAINING:
 674                 case SSH_CHANNEL_OUTPUT_DRAINING:
 675                         if (!compat13)
 676                                 fatal("cannot happen: OUT_DRAIN");
 677                         return i;
 678                 default:
 679                         fatal("channel_find_open: bad channel type %d", c->type);
 680                         /* NOTREACHED */
 681                 }
 682         }
 683         return -1;
 684 }
 685
 686 /*
 687  * Returns a message describing the currently open forwarded connections,
 688  * suitable for sending to the client.  The message contains crlf pairs for
 689  * newlines.
 690  */
 691 char *
 692 channel_open_message(void)
 693 {
 694         Buffer buffer;
 695         Channel *c;
 696         char buf[1024], *cp;
 697         u_int i;
 698
 699         buffer_init(&buffer);
 700         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 701         buffer_append(&buffer, buf, strlen(buf));
 702         for (i = 0; i < channels_alloc; i++) {
 703                 c = channels[i];
 704                 if (c == NULL)
 705                         continue;
 706                 switch (c->type) {
 707                 case SSH_CHANNEL_X11_LISTENER:
 708                 case SSH_CHANNEL_PORT_LISTENER:
 709                 case SSH_CHANNEL_RPORT_LISTENER:
 710                 case SSH_CHANNEL_CLOSED:
 711                 case SSH_CHANNEL_AUTH_SOCKET:
 712                 case SSH_CHANNEL_ZOMBIE:
 713                 case SSH_CHANNEL_ABANDONED:
 714                 case SSH_CHANNEL_MUX_LISTENER:
 715                 case SSH_CHANNEL_UNIX_LISTENER:
 716                 case SSH_CHANNEL_RUNIX_LISTENER:
 717                         continue;
 718                 case SSH_CHANNEL_LARVAL:
 719                 case SSH_CHANNEL_OPENING:
 720                 case SSH_CHANNEL_CONNECTING:
 721                 case SSH_CHANNEL_DYNAMIC:
 722                 case SSH_CHANNEL_OPEN:
 723                 case SSH_CHANNEL_X11_OPEN:
 724                 case SSH_CHANNEL_INPUT_DRAINING:
 725                 case SSH_CHANNEL_OUTPUT_DRAINING:
 726                 case SSH_CHANNEL_MUX_PROXY:
 727                 case SSH_CHANNEL_MUX_CLIENT:
 728                         snprintf(buf, sizeof buf,
 729                             "  #%d %.300s (t%d r%d i%u/%d o%u/%d fd %d/%d cc %d)\r\n",
 730                             c->self, c->remote_name,
 731                             c->type, c->remote_id,
 732                             c->istate, buffer_len(&c->input),
 733                             c->ostate, buffer_len(&c->output),
 734                             c->rfd, c->wfd, c->ctl_chan);
 735                         buffer_append(&buffer, buf, strlen(buf));
 736                         continue;
 737                 default:
 738                         fatal("channel_open_message: bad channel type %d", c->type);
 739                         /* NOTREACHED */
 740                 }
 741         }
 742         buffer_append(&buffer, "\0", 1);
 743         cp = xstrdup((char *)buffer_ptr(&buffer));
 744         buffer_free(&buffer);
 745         return cp;
 746 }
 747
 748 void
 749 channel_send_open(int id)
 750 {
 751         Channel *c = channel_lookup(id);
 752
 753         if (c == NULL) {
 754                 logit("channel_send_open: %d: bad id", id);
 755                 return;
 756         }
 757         debug2("channel %d: send open", id);
 758         packet_start(SSH2_MSG_CHANNEL_OPEN);
 759         packet_put_cstring(c->ctype);
 760         packet_put_int(c->self);
 761         packet_put_int(c->local_window);
 762         packet_put_int(c->local_maxpacket);
 763         packet_send();
 764 }
 765
 766 void
 767 channel_request_start(int id, char *service, int wantconfirm)
 768 {
 769         Channel *c = channel_lookup(id);
 770
 771         if (c == NULL) {
 772                 logit("channel_request_start: %d: unknown channel id", id);
 773                 return;
 774         }
 775         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 776         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 777         packet_put_int(c->remote_id);
 778         packet_put_cstring(service);
 779         packet_put_char(wantconfirm);
 780 }
 781
 782 void
 783 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 784     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 785 {
 786         struct channel_confirm *cc;
 787         Channel *c;
 788
 789         if ((c = channel_lookup(id)) == NULL)
 790                 fatal("channel_register_expect: %d: bad id", id);
 791
 792         cc = xcalloc(1, sizeof(*cc));
 793         cc->cb = cb;
 794         cc->abandon_cb = abandon_cb;
 795         cc->ctx = ctx;
 796         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 797 }
 798
 799 void
 800 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 801 {
 802         Channel *c = channel_lookup(id);
 803
 804         if (c == NULL) {
 805                 logit("channel_register_open_confirm: %d: bad id", id);
 806                 return;
 807         }
 808         c->open_confirm = fn;
 809         c->open_confirm_ctx = ctx;
 810 }
 811
 812 void
 813 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 814 {
 815         Channel *c = channel_by_id(id);
 816
 817         if (c == NULL) {
 818                 logit("channel_register_cleanup: %d: bad id", id);
 819                 return;
 820         }
 821         c->detach_user = fn;
 822         c->detach_close = do_close;
 823 }
 824
 825 void
 826 channel_cancel_cleanup(int id)
 827 {
 828         Channel *c = channel_by_id(id);
 829
 830         if (c == NULL) {
 831                 logit("channel_cancel_cleanup: %d: bad id", id);
 832                 return;
 833         }
 834         c->detach_user = NULL;
 835         c->detach_close = 0;
 836 }
 837
 838 void
 839 channel_register_filter(int id, channel_infilter_fn *ifn,
 840     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 841 {
 842         Channel *c = channel_lookup(id);
 843
 844         if (c == NULL) {
 845                 logit("channel_register_filter: %d: bad id", id);
 846                 return;
 847         }
 848         c->input_filter = ifn;
 849         c->output_filter = ofn;
 850         c->filter_ctx = ctx;
 851         c->filter_cleanup = cfn;
 852 }
 853
 854 void
 855 channel_set_fds(int id, int rfd, int wfd, int efd,
 856     int extusage, int nonblock, int is_tty, u_int window_max)
 857 {
 858         Channel *c = channel_lookup(id);
 859
 860         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 861                 fatal("channel_activate for non-larval channel %d.", id);
 862         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 863         c->type = SSH_CHANNEL_OPEN;
 864         c->local_window = c->local_window_max = window_max;
 865         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 866         packet_put_int(c->remote_id);
 867         packet_put_int(c->local_window);
 868         packet_send();
 869 }
 870
 871 /*
 872  * 'channel_pre*' are called just before select() to add any bits relevant to
 873  * channels in the select bitmasks.
 874  */
 875 /*
 876  * 'channel_post*': perform any appropriate operations for channels which
 877  * have events pending.
 878  */
 879 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 880 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 881 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 882
 883 /* ARGSUSED */
 884 static void
 885 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 886 {
 887         FD_SET(c->sock, readset);
 888 }
 889
 890 /* ARGSUSED */
 891 static void
 892 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 893 {
 894         debug3("channel %d: waiting for connection", c->self);
 895         FD_SET(c->sock, writeset);
 896 }
 897
 898 static void
 899 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 900 {
 901         if (buffer_len(&c->input) < packet_get_maxsize())
 902                 FD_SET(c->sock, readset);
 903         if (buffer_len(&c->output) > 0)
 904                 FD_SET(c->sock, writeset);
 905 }
 906
 907 static void
 908 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 909 {
 910         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 911
 912         if (c->istate == CHAN_INPUT_OPEN &&
 913             limit > 0 &&
 914             buffer_len(&c->input) < limit &&
 915             buffer_check_alloc(&c->input, CHAN_RBUF))
 916                 FD_SET(c->rfd, readset);
 917         if (c->ostate == CHAN_OUTPUT_OPEN ||
 918             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 919                 if (buffer_len(&c->output) > 0) {
 920                         FD_SET(c->wfd, writeset);
 921                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 922                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 923                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 924                                     c->self, c->efd, buffer_len(&c->extended));
 925                         else
 926                                 chan_obuf_empty(c);
 927                 }
 928         }
 929         /** XXX check close conditions, too */
 930         if (compat20 && c->efd != -1 &&
 931             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 932                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 933                     buffer_len(&c->extended) > 0)
 934                         FD_SET(c->efd, writeset);
 935                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 936                     (c->extended_usage == CHAN_EXTENDED_READ ||
 937                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 938                     buffer_len(&c->extended) < c->remote_window)
 939                         FD_SET(c->efd, readset);
 940         }
 941         /* XXX: What about efd? races? */
 942 }
 943
 944 /* ARGSUSED */
 945 static void
 946 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 947 {
 948         if (buffer_len(&c->input) == 0) {
 949                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 950                 packet_put_int(c->remote_id);
 951                 packet_send();
 952                 c->type = SSH_CHANNEL_CLOSED;
 953                 debug2("channel %d: closing after input drain.", c->self);
 954         }
 955 }
 956
 957 /* ARGSUSED */
 958 static void
 959 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 960 {
 961         if (buffer_len(&c->output) == 0)
 962                 chan_mark_dead(c);
 963         else
 964                 FD_SET(c->sock, writeset);
 965 }
 966
 967 /*
 968  * This is a special state for X11 authentication spoofing.  An opened X11
 969  * connection (when authentication spoofing is being done) remains in this
 970  * state until the first packet has been completely read.  The authentication
 971  * data in that packet is then substituted by the real data if it matches the
 972  * fake data, and the channel is put into normal mode.
 973  * XXX All this happens at the client side.
 974  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 975  */
 976 static int
 977 x11_open_helper(Buffer *b)
 978 {
 979         u_char *ucp;
 980         u_int proto_len, data_len;
 981
 982         /* Is this being called after the refusal deadline? */
 983         if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
 984                 verbose("Rejected X11 connection after ForwardX11Timeout "
 985                     "expired");
 986                 return -1;
 987         }
 988
 989         /* Check if the fixed size part of the packet is in buffer. */
 990         if (buffer_len(b) < 12)
 991                 return 0;
 992
 993         /* Parse the lengths of variable-length fields. */
 994         ucp = buffer_ptr(b);
 995         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 996                 proto_len = 256 * ucp[6] + ucp[7];
 997                 data_len = 256 * ucp[8] + ucp[9];
 998         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 999                 proto_len = ucp[6] + 256 * ucp[7];
1000                 data_len = ucp[8] + 256 * ucp[9];
1001         } else {
1002                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
1003                     ucp[0]);
1004                 return -1;
1005         }
1006
1007         /* Check if the whole packet is in buffer. */
1008         if (buffer_len(b) <
1009             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
1010                 return 0;
1011
1012         /* Check if authentication protocol matches. */
1013         if (proto_len != strlen(x11_saved_proto) ||
1014             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
1015                 debug2("X11 connection uses different authentication protocol.");
1016                 return -1;
1017         }
1018         /* Check if authentication data matches our fake data. */
1019         if (data_len != x11_fake_data_len ||
1020             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
1021                 x11_fake_data, x11_fake_data_len) != 0) {
1022                 debug2("X11 auth data does not match fake data.");
1023                 return -1;
1024         }
1025         /* Check fake data length */
1026         if (x11_fake_data_len != x11_saved_data_len) {
1027                 error("X11 fake_data_len %d != saved_data_len %d",
1028                     x11_fake_data_len, x11_saved_data_len);
1029                 return -1;
1030         }
1031         /*
1032          * Received authentication protocol and data match
1033          * our fake data. Substitute the fake data with real
1034          * data.
1035          */
1036         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
1037             x11_saved_data, x11_saved_data_len);
1038         return 1;
1039 }
1040
1041 static void
1042 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
1043 {
1044         int ret = x11_open_helper(&c->output);
1045
1046         if (ret == 1) {
1047                 /* Start normal processing for the channel. */
1048                 c->type = SSH_CHANNEL_OPEN;
1049                 channel_pre_open_13(c, readset, writeset);
1050         } else if (ret == -1) {
1051                 /*
1052                  * We have received an X11 connection that has bad
1053                  * authentication information.
1054                  */
1055                 logit("X11 connection rejected because of wrong authentication.");
1056                 buffer_clear(&c->input);
1057                 buffer_clear(&c->output);
1058                 channel_close_fd(&c->sock);
1059                 c->sock = -1;
1060                 c->type = SSH_CHANNEL_CLOSED;
1061                 packet_start(SSH_MSG_CHANNEL_CLOSE);
1062                 packet_put_int(c->remote_id);
1063                 packet_send();
1064         }
1065 }
1066
1067 static void
1068 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
1069 {
1070         int ret = x11_open_helper(&c->output);
1071
1072         /* c->force_drain = 1; */
1073
1074         if (ret == 1) {
1075                 c->type = SSH_CHANNEL_OPEN;
1076                 channel_pre_open(c, readset, writeset);
1077         } else if (ret == -1) {
1078                 logit("X11 connection rejected because of wrong authentication.");
1079                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1080                 chan_read_failed(c);
1081                 buffer_clear(&c->input);
1082                 chan_ibuf_empty(c);
1083                 buffer_clear(&c->output);
1084                 /* for proto v1, the peer will send an IEOF */
1085                 if (compat20)
1086                         chan_write_failed(c);
1087                 else
1088                         c->type = SSH_CHANNEL_OPEN;
1089                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1090         }
1091 }
1092
1093 static void
1094 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1095 {
1096         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1097             buffer_check_alloc(&c->input, CHAN_RBUF))
1098                 FD_SET(c->rfd, readset);
1099         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1100                 /* clear buffer immediately (discard any partial packet) */
1101                 buffer_clear(&c->input);
1102                 chan_ibuf_empty(c);
1103                 /* Start output drain. XXX just kill chan? */
1104                 chan_rcvd_oclose(c);
1105         }
1106         if (c->ostate == CHAN_OUTPUT_OPEN ||
1107             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1108                 if (buffer_len(&c->output) > 0)
1109                         FD_SET(c->wfd, writeset);
1110                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1111                         chan_obuf_empty(c);
1112         }
1113 }
1114
1115 /* try to decode a socks4 header */
1116 /* ARGSUSED */
1117 static int
1118 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1119 {
1120         char *p, *host;
1121         u_int len, have, i, found, need;
1122         char username[256];
1123         struct {
1124                 u_int8_t version;
1125                 u_int8_t command;
1126                 u_int16_t dest_port;
1127                 struct in_addr dest_addr;
1128         } s4_req, s4_rsp;
1129
1130         debug2("channel %d: decode socks4", c->self);
1131
1132         have = buffer_len(&c->input);
1133         len = sizeof(s4_req);
1134         if (have < len)
1135                 return 0;
1136         p = (char *)buffer_ptr(&c->input);
1137
1138         need = 1;
1139         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1140         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1141                 debug2("channel %d: socks4a request", c->self);
1142                 /* ... and needs an extra string (the hostname) */
1143                 need = 2;
1144         }
1145         /* Check for terminating NUL on the string(s) */
1146         for (found = 0, i = len; i < have; i++) {
1147                 if (p[i] == '\0') {
1148                         found++;
1149                         if (found == need)
1150                                 break;
1151                 }
1152                 if (i > 1024) {
1153                         /* the peer is probably sending garbage */
1154                         debug("channel %d: decode socks4: too long",
1155                             c->self);
1156                         return -1;
1157                 }
1158         }
1159         if (found < need)
1160                 return 0;
1161         buffer_get(&c->input, (char *)&s4_req.version, 1);
1162         buffer_get(&c->input, (char *)&s4_req.command, 1);
1163         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1164         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1165         have = buffer_len(&c->input);
1166         p = (char *)buffer_ptr(&c->input);
1167         if (memchr(p, '\0', have) == NULL)
1168                 fatal("channel %d: decode socks4: user not nul terminated",
1169                     c->self);
1170         len = strlen(p);
1171         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1172         len++;                                  /* trailing '\0' */
1173         if (len > have)
1174                 fatal("channel %d: decode socks4: len %d > have %d",
1175                     c->self, len, have);
1176         strlcpy(username, p, sizeof(username));
1177         buffer_consume(&c->input, len);
1178
1179         free(c->path);
1180         c->path = NULL;
1181         if (need == 1) {                        /* SOCKS4: one string */
1182                 host = inet_ntoa(s4_req.dest_addr);
1183                 c->path = xstrdup(host);
1184         } else {                                /* SOCKS4A: two strings */
1185                 have = buffer_len(&c->input);
1186                 p = (char *)buffer_ptr(&c->input);
1187                 len = strlen(p);
1188                 debug2("channel %d: decode socks4a: host %s/%d",
1189                     c->self, p, len);
1190                 len++;                          /* trailing '\0' */
1191                 if (len > have)
1192                         fatal("channel %d: decode socks4a: len %d > have %d",
1193                             c->self, len, have);
1194                 if (len > NI_MAXHOST) {
1195                         error("channel %d: hostname \"%.100s\" too long",
1196                             c->self, p);
1197                         return -1;
1198                 }
1199                 c->path = xstrdup(p);
1200                 buffer_consume(&c->input, len);
1201         }
1202         c->host_port = ntohs(s4_req.dest_port);
1203
1204         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1205             c->self, c->path, c->host_port, s4_req.command);
1206
1207         if (s4_req.command != 1) {
1208                 debug("channel %d: cannot handle: %s cn %d",
1209                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1210                 return -1;
1211         }
1212         s4_rsp.version = 0;                     /* vn: 0 for reply */
1213         s4_rsp.command = 90;                    /* cd: req granted */
1214         s4_rsp.dest_port = 0;                   /* ignored */
1215         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1216         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1217         return 1;
1218 }
1219
1220 /* try to decode a socks5 header */
1221 #define SSH_SOCKS5_AUTHDONE     0x1000
1222 #define SSH_SOCKS5_NOAUTH       0x00
1223 #define SSH_SOCKS5_IPV4         0x01
1224 #define SSH_SOCKS5_DOMAIN       0x03
1225 #define SSH_SOCKS5_IPV6         0x04
1226 #define SSH_SOCKS5_CONNECT      0x01
1227 #define SSH_SOCKS5_SUCCESS      0x00
1228
1229 /* ARGSUSED */
1230 static int
1231 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1232 {
1233         struct {
1234                 u_int8_t version;
1235                 u_int8_t command;
1236                 u_int8_t reserved;
1237                 u_int8_t atyp;
1238         } s5_req, s5_rsp;
1239         u_int16_t dest_port;
1240         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1241         u_char *p;
1242         u_int have, need, i, found, nmethods, addrlen, af;
1243
1244         debug2("channel %d: decode socks5", c->self);
1245         p = buffer_ptr(&c->input);
1246         if (p[0] != 0x05)
1247                 return -1;
1248         have = buffer_len(&c->input);
1249         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1250                 /* format: ver | nmethods | methods */
1251                 if (have < 2)
1252                         return 0;
1253                 nmethods = p[1];
1254                 if (have < nmethods + 2)
1255                         return 0;
1256                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1257                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1258                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1259                                 found = 1;
1260                                 break;
1261                         }
1262                 }
1263                 if (!found) {
1264                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1265                             c->self);
1266                         return -1;
1267                 }
1268                 buffer_consume(&c->input, nmethods + 2);
1269                 buffer_put_char(&c->output, 0x05);              /* version */
1270                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1271                 FD_SET(c->sock, writeset);
1272                 c->flags |= SSH_SOCKS5_AUTHDONE;
1273                 debug2("channel %d: socks5 auth done", c->self);
1274                 return 0;                               /* need more */
1275         }
1276         debug2("channel %d: socks5 post auth", c->self);
1277         if (have < sizeof(s5_req)+1)
1278                 return 0;                       /* need more */
1279         memcpy(&s5_req, p, sizeof(s5_req));
1280         if (s5_req.version != 0x05 ||
1281             s5_req.command != SSH_SOCKS5_CONNECT ||
1282             s5_req.reserved != 0x00) {
1283                 debug2("channel %d: only socks5 connect supported", c->self);
1284                 return -1;
1285         }
1286         switch (s5_req.atyp){
1287         case SSH_SOCKS5_IPV4:
1288                 addrlen = 4;
1289                 af = AF_INET;
1290                 break;
1291         case SSH_SOCKS5_DOMAIN:
1292                 addrlen = p[sizeof(s5_req)];
1293                 af = -1;
1294                 break;
1295         case SSH_SOCKS5_IPV6:
1296                 addrlen = 16;
1297                 af = AF_INET6;
1298                 break;
1299         default:
1300                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1301                 return -1;
1302         }
1303         need = sizeof(s5_req) + addrlen + 2;
1304         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1305                 need++;
1306         if (have < need)
1307                 return 0;
1308         buffer_consume(&c->input, sizeof(s5_req));
1309         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1310                 buffer_consume(&c->input, 1);    /* host string length */
1311         buffer_get(&c->input, &dest_addr, addrlen);
1312         buffer_get(&c->input, (char *)&dest_port, 2);
1313         dest_addr[addrlen] = '\0';
1314         free(c->path);
1315         c->path = NULL;
1316         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1317                 if (addrlen >= NI_MAXHOST) {
1318                         error("channel %d: dynamic request: socks5 hostname "
1319                             "\"%.100s\" too long", c->self, dest_addr);
1320                         return -1;
1321                 }
1322                 c->path = xstrdup(dest_addr);
1323         } else {
1324                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1325                         return -1;
1326                 c->path = xstrdup(ntop);
1327         }
1328         c->host_port = ntohs(dest_port);
1329
1330         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1331             c->self, c->path, c->host_port, s5_req.command);
1332
1333         s5_rsp.version = 0x05;
1334         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1335         s5_rsp.reserved = 0;                    /* ignored */
1336         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1337         dest_port = 0;                          /* ignored */
1338
1339         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1340         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1341         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1342         return 1;
1343 }
1344
1345 Channel *
1346 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1347     int in, int out)
1348 {
1349         Channel *c;
1350
1351         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1352             port_to_connect);
1353
1354         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1355             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1356             0, "stdio-forward", /*nonblock*/0);
1357
1358         c->path = xstrdup(host_to_connect);
1359         c->host_port = port_to_connect;
1360         c->listening_port = 0;
1361         c->force_drain = 1;
1362
1363         channel_register_fds(c, in, out, -1, 0, 1, 0);
1364         port_open_helper(c, "direct-tcpip");
1365
1366         return c;
1367 }
1368
1369 /* dynamic port forwarding */
1370 static void
1371 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1372 {
1373         u_char *p;
1374         u_int have;
1375         int ret;
1376
1377         have = buffer_len(&c->input);
1378         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1379         /* buffer_dump(&c->input); */
1380         /* check if the fixed size part of the packet is in buffer. */
1381         if (have < 3) {
1382                 /* need more */
1383                 FD_SET(c->sock, readset);
1384                 return;
1385         }
1386         /* try to guess the protocol */
1387         p = buffer_ptr(&c->input);
1388         switch (p[0]) {
1389         case 0x04:
1390                 ret = channel_decode_socks4(c, readset, writeset);
1391                 break;
1392         case 0x05:
1393                 ret = channel_decode_socks5(c, readset, writeset);
1394                 break;
1395         default:
1396                 ret = -1;
1397                 break;
1398         }
1399         if (ret < 0) {
1400                 chan_mark_dead(c);
1401         } else if (ret == 0) {
1402                 debug2("channel %d: pre_dynamic: need more", c->self);
1403                 /* need more */
1404                 FD_SET(c->sock, readset);
1405         } else {
1406                 /* switch to the next state */
1407                 c->type = SSH_CHANNEL_OPENING;
1408                 port_open_helper(c, "direct-tcpip");
1409         }
1410 }
1411
1412 /* This is our fake X11 server socket. */
1413 /* ARGSUSED */
1414 static void
1415 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1416 {
1417         Channel *nc;
1418         struct sockaddr_storage addr;
1419         int newsock, oerrno;
1420         socklen_t addrlen;
1421         char buf[16384], *remote_ipaddr;
1422         int remote_port;
1423
1424         if (FD_ISSET(c->sock, readset)) {
1425                 debug("X11 connection requested.");
1426                 addrlen = sizeof(addr);
1427                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1428                 if (c->single_connection) {
1429                         oerrno = errno;
1430                         debug2("single_connection: closing X11 listener.");
1431                         channel_close_fd(&c->sock);
1432                         chan_mark_dead(c);
1433                         errno = oerrno;
1434                 }
1435                 if (newsock < 0) {
1436                         if (errno != EINTR && errno != EWOULDBLOCK &&
1437                             errno != ECONNABORTED)
1438                                 error("accept: %.100s", strerror(errno));
1439                         if (errno == EMFILE || errno == ENFILE)
1440                                 c->notbefore = monotime() + 1;
1441                         return;
1442                 }
1443                 set_nodelay(newsock);
1444                 remote_ipaddr = get_peer_ipaddr(newsock);
1445                 remote_port = get_peer_port(newsock);
1446                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1447                     remote_ipaddr, remote_port);
1448
1449                 nc = channel_new("accepted x11 socket",
1450                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1451                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1452                 if (compat20) {
1453                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1454                         packet_put_cstring("x11");
1455                         packet_put_int(nc->self);
1456                         packet_put_int(nc->local_window_max);
1457                         packet_put_int(nc->local_maxpacket);
1458                         /* originator ipaddr and port */
1459                         packet_put_cstring(remote_ipaddr);
1460                         if (datafellows & SSH_BUG_X11FWD) {
1461                                 debug2("ssh2 x11 bug compat mode");
1462                         } else {
1463                                 packet_put_int(remote_port);
1464                         }
1465                         packet_send();
1466                 } else {
1467                         packet_start(SSH_SMSG_X11_OPEN);
1468                         packet_put_int(nc->self);
1469                         if (packet_get_protocol_flags() &
1470                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1471                                 packet_put_cstring(buf);
1472                         packet_send();
1473                 }
1474                 free(remote_ipaddr);
1475         }
1476 }
1477
1478 static void
1479 port_open_helper(Channel *c, char *rtype)
1480 {
1481         char buf[1024];
1482         char *local_ipaddr = get_local_ipaddr(c->sock);
1483         int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock);
1484         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1485         int remote_port = get_peer_port(c->sock);
1486
1487         if (remote_port == -1) {
1488                 /* Fake addr/port to appease peers that validate it (Tectia) */
1489                 free(remote_ipaddr);
1490                 remote_ipaddr = xstrdup("127.0.0.1");
1491                 remote_port = 65535;
1492         }
1493
1494         snprintf(buf, sizeof buf,
1495             "%s: listening port %d for %.100s port %d, "
1496             "connect from %.200s port %d to %.100s port %d",
1497             rtype, c->listening_port, c->path, c->host_port,
1498             remote_ipaddr, remote_port, local_ipaddr, local_port);
1499
1500         free(c->remote_name);
1501         c->remote_name = xstrdup(buf);
1502
1503         if (compat20) {
1504                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1505                 packet_put_cstring(rtype);
1506                 packet_put_int(c->self);
1507                 packet_put_int(c->local_window_max);
1508                 packet_put_int(c->local_maxpacket);
1509                 if (strcmp(rtype, "direct-tcpip") == 0) {
1510                         /* target host, port */
1511                         packet_put_cstring(c->path);
1512                         packet_put_int(c->host_port);
1513                 } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
1514                         /* target path */
1515                         packet_put_cstring(c->path);
1516                 } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1517                         /* listen path */
1518                         packet_put_cstring(c->path);
1519                 } else {
1520                         /* listen address, port */
1521                         packet_put_cstring(c->path);
1522                         packet_put_int(local_port);
1523                 }
1524                 if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1525                         /* reserved for future owner/mode info */
1526                         packet_put_cstring("");
1527                 } else {
1528                         /* originator host and port */
1529                         packet_put_cstring(remote_ipaddr);
1530                         packet_put_int((u_int)remote_port);
1531                 }
1532                 packet_send();
1533         } else {
1534                 packet_start(SSH_MSG_PORT_OPEN);
1535                 packet_put_int(c->self);
1536                 packet_put_cstring(c->path);
1537                 packet_put_int(c->host_port);
1538                 if (packet_get_protocol_flags() &
1539                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1540                         packet_put_cstring(c->remote_name);
1541                 packet_send();
1542         }
1543         free(remote_ipaddr);
1544         free(local_ipaddr);
1545 }
1546
1547 static void
1548 channel_set_reuseaddr(int fd)
1549 {
1550         int on = 1;
1551
1552         /*
1553          * Set socket options.
1554          * Allow local port reuse in TIME_WAIT.
1555          */
1556         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1557                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1558 }
1559
1560 void
1561 channel_set_x11_refuse_time(u_int refuse_time)
1562 {
1563         x11_refuse_time = refuse_time;
1564 }
1565
1566 /*
1567  * This socket is listening for connections to a forwarded TCP/IP port.
1568  */
1569 /* ARGSUSED */
1570 static void
1571 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1572 {
1573         Channel *nc;
1574         struct sockaddr_storage addr;
1575         int newsock, nextstate;
1576         socklen_t addrlen;
1577         char *rtype;
1578
1579         if (FD_ISSET(c->sock, readset)) {
1580                 debug("Connection to port %d forwarding "
1581                     "to %.100s port %d requested.",
1582                     c->listening_port, c->path, c->host_port);
1583
1584                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1585                         nextstate = SSH_CHANNEL_OPENING;
1586                         rtype = "forwarded-tcpip";
1587                 } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
1588                         nextstate = SSH_CHANNEL_OPENING;
1589                         rtype = "forwarded-streamlocal@openssh.com";
1590                 } else if (c->host_port == PORT_STREAMLOCAL) {
1591                         nextstate = SSH_CHANNEL_OPENING;
1592                         rtype = "direct-streamlocal@openssh.com";
1593                 } else if (c->host_port == 0) {
1594                         nextstate = SSH_CHANNEL_DYNAMIC;
1595                         rtype = "dynamic-tcpip";
1596                 } else {
1597                         nextstate = SSH_CHANNEL_OPENING;
1598                         rtype = "direct-tcpip";
1599                 }
1600
1601                 addrlen = sizeof(addr);
1602                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1603                 if (newsock < 0) {
1604                         if (errno != EINTR && errno != EWOULDBLOCK &&
1605                             errno != ECONNABORTED)
1606                                 error("accept: %.100s", strerror(errno));
1607                         if (errno == EMFILE || errno == ENFILE)
1608                                 c->notbefore = monotime() + 1;
1609                         return;
1610                 }
1611                 if (c->host_port != PORT_STREAMLOCAL)
1612                         set_nodelay(newsock);
1613                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1614                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1615                 nc->listening_port = c->listening_port;
1616                 nc->host_port = c->host_port;
1617                 if (c->path != NULL)
1618                         nc->path = xstrdup(c->path);
1619
1620                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1621                         port_open_helper(nc, rtype);
1622         }
1623 }
1624
1625 /*
1626  * This is the authentication agent socket listening for connections from
1627  * clients.
1628  */
1629 /* ARGSUSED */
1630 static void
1631 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1632 {
1633         Channel *nc;
1634         int newsock;
1635         struct sockaddr_storage addr;
1636         socklen_t addrlen;
1637
1638         if (FD_ISSET(c->sock, readset)) {
1639                 addrlen = sizeof(addr);
1640                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1641                 if (newsock < 0) {
1642                         error("accept from auth socket: %.100s",
1643                             strerror(errno));
1644                         if (errno == EMFILE || errno == ENFILE)
1645                                 c->notbefore = monotime() + 1;
1646                         return;
1647                 }
1648                 nc = channel_new("accepted auth socket",
1649                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1650                     c->local_window_max, c->local_maxpacket,
1651                     0, "accepted auth socket", 1);
1652                 if (compat20) {
1653                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1654                         packet_put_cstring("auth-agent@openssh.com");
1655                         packet_put_int(nc->self);
1656                         packet_put_int(c->local_window_max);
1657                         packet_put_int(c->local_maxpacket);
1658                 } else {
1659                         packet_start(SSH_SMSG_AGENT_OPEN);
1660                         packet_put_int(nc->self);
1661                 }
1662                 packet_send();
1663         }
1664 }
1665
1666 /* ARGSUSED */
1667 static void
1668 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1669 {
1670         int err = 0, sock;
1671         socklen_t sz = sizeof(err);
1672
1673         if (FD_ISSET(c->sock, writeset)) {
1674                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1675                         err = errno;
1676                         error("getsockopt SO_ERROR failed");
1677                 }
1678                 if (err == 0) {
1679                         debug("channel %d: connected to %s port %d",
1680                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1681                         channel_connect_ctx_free(&c->connect_ctx);
1682                         c->type = SSH_CHANNEL_OPEN;
1683                         if (compat20) {
1684                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1685                                 packet_put_int(c->remote_id);
1686                                 packet_put_int(c->self);
1687                                 packet_put_int(c->local_window);
1688                                 packet_put_int(c->local_maxpacket);
1689                         } else {
1690                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1691                                 packet_put_int(c->remote_id);
1692                                 packet_put_int(c->self);
1693                         }
1694                 } else {
1695                         debug("channel %d: connection failed: %s",
1696                             c->self, strerror(err));
1697                         /* Try next address, if any */
1698                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1699                                 close(c->sock);
1700                                 c->sock = c->rfd = c->wfd = sock;
1701                                 channel_max_fd = channel_find_maxfd();
1702                                 return;
1703                         }
1704                         /* Exhausted all addresses */
1705                         error("connect_to %.100s port %d: failed.",
1706                             c->connect_ctx.host, c->connect_ctx.port);
1707                         channel_connect_ctx_free(&c->connect_ctx);
1708                         if (compat20) {
1709                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1710                                 packet_put_int(c->remote_id);
1711                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1712                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1713                                         packet_put_cstring(strerror(err));
1714                                         packet_put_cstring("");
1715                                 }
1716                         } else {
1717                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1718                                 packet_put_int(c->remote_id);
1719                         }
1720                         chan_mark_dead(c);
1721                 }
1722                 packet_send();
1723         }
1724 }
1725
1726 /* ARGSUSED */
1727 static int
1728 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1729 {
1730         char buf[CHAN_RBUF];
1731         int len, force;
1732
1733         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1734         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1735                 errno = 0;
1736                 len = read(c->rfd, buf, sizeof(buf));
1737                 if (len < 0 && (errno == EINTR ||
1738                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1739                         return 1;
1740 #ifndef PTY_ZEROREAD
1741                 if (len <= 0) {
1742 #else
1743                 if ((!c->isatty && len <= 0) ||
1744                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1745 #endif
1746                         debug2("channel %d: read<=0 rfd %d len %d",
1747                             c->self, c->rfd, len);
1748                         if (c->type != SSH_CHANNEL_OPEN) {
1749                                 debug2("channel %d: not open", c->self);
1750                                 chan_mark_dead(c);
1751                                 return -1;
1752                         } else if (compat13) {
1753                                 buffer_clear(&c->output);
1754                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1755                                 debug2("channel %d: input draining.", c->self);
1756                         } else {
1757                                 chan_read_failed(c);
1758                         }
1759                         return -1;
1760                 }
1761                 if (c->input_filter != NULL) {
1762                         if (c->input_filter(c, buf, len) == -1) {
1763                                 debug2("channel %d: filter stops", c->self);
1764                                 chan_read_failed(c);
1765                         }
1766                 } else if (c->datagram) {
1767                         buffer_put_string(&c->input, buf, len);
1768                 } else {
1769                         buffer_append(&c->input, buf, len);
1770                 }
1771         }
1772         return 1;
1773 }
1774
1775 /* ARGSUSED */
1776 static int
1777 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1778 {
1779         struct termios tio;
1780         u_char *data = NULL, *buf;
1781         u_int dlen, olen = 0;
1782         int len;
1783
1784         /* Send buffered output data to the socket. */
1785         if (c->wfd != -1 &&
1786             FD_ISSET(c->wfd, writeset) &&
1787             buffer_len(&c->output) > 0) {
1788                 olen = buffer_len(&c->output);
1789                 if (c->output_filter != NULL) {
1790                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1791                                 debug2("channel %d: filter stops", c->self);
1792                                 if (c->type != SSH_CHANNEL_OPEN)
1793                                         chan_mark_dead(c);
1794                                 else
1795                                         chan_write_failed(c);
1796                                 return -1;
1797                         }
1798                 } else if (c->datagram) {
1799                         buf = data = buffer_get_string(&c->output, &dlen);
1800                 } else {
1801                         buf = data = buffer_ptr(&c->output);
1802                         dlen = buffer_len(&c->output);
1803                 }
1804
1805                 if (c->datagram) {
1806                         /* ignore truncated writes, datagrams might get lost */
1807                         len = write(c->wfd, buf, dlen);
1808                         free(data);
1809                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1810                             errno == EWOULDBLOCK))
1811                                 return 1;
1812                         if (len <= 0) {
1813                                 if (c->type != SSH_CHANNEL_OPEN)
1814                                         chan_mark_dead(c);
1815                                 else
1816                                         chan_write_failed(c);
1817                                 return -1;
1818                         }
1819                         goto out;
1820                 }
1821 #ifdef _AIX
1822                 /* XXX: Later AIX versions can't push as much data to tty */
1823                 if (compat20 && c->wfd_isatty)
1824                         dlen = MIN(dlen, 8*1024);
1825 #endif
1826
1827                 len = write(c->wfd, buf, dlen);
1828                 if (len < 0 &&
1829                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1830                         return 1;
1831                 if (len <= 0) {
1832                         if (c->type != SSH_CHANNEL_OPEN) {
1833                                 debug2("channel %d: not open", c->self);
1834                                 chan_mark_dead(c);
1835                                 return -1;
1836                         } else if (compat13) {
1837                                 buffer_clear(&c->output);
1838                                 debug2("channel %d: input draining.", c->self);
1839                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1840                         } else {
1841                                 chan_write_failed(c);
1842                         }
1843                         return -1;
1844                 }
1845 #ifndef BROKEN_TCGETATTR_ICANON
1846                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1847                         if (tcgetattr(c->wfd, &tio) == 0 &&
1848                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1849                                 /*
1850                                  * Simulate echo to reduce the impact of
1851                                  * traffic analysis. We need to match the
1852                                  * size of a SSH2_MSG_CHANNEL_DATA message
1853                                  * (4 byte channel id + buf)
1854                                  */
1855                                 packet_send_ignore(4 + len);
1856                                 packet_send();
1857                         }
1858                 }
1859 #endif
1860                 buffer_consume(&c->output, len);
1861         }
1862  out:
1863         if (compat20 && olen > 0)
1864                 c->local_consumed += olen - buffer_len(&c->output);
1865         return 1;
1866 }
1867
1868 static int
1869 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1870 {
1871         char buf[CHAN_RBUF];
1872         int len;
1873
1874 /** XXX handle drain efd, too */
1875         if (c->efd != -1) {
1876                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1877                     FD_ISSET(c->efd, writeset) &&
1878                     buffer_len(&c->extended) > 0) {
1879                         len = write(c->efd, buffer_ptr(&c->extended),
1880                             buffer_len(&c->extended));
1881                         debug2("channel %d: written %d to efd %d",
1882                             c->self, len, c->efd);
1883                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1884                             errno == EWOULDBLOCK))
1885                                 return 1;
1886                         if (len <= 0) {
1887                                 debug2("channel %d: closing write-efd %d",
1888                                     c->self, c->efd);
1889                                 channel_close_fd(&c->efd);
1890                         } else {
1891                                 buffer_consume(&c->extended, len);
1892                                 c->local_consumed += len;
1893                         }
1894                 } else if (c->efd != -1 &&
1895                     (c->extended_usage == CHAN_EXTENDED_READ ||
1896                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1897                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1898                         len = read(c->efd, buf, sizeof(buf));
1899                         debug2("channel %d: read %d from efd %d",
1900                             c->self, len, c->efd);
1901                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1902                             errno == EWOULDBLOCK) && !c->detach_close)))
1903                                 return 1;
1904                         if (len <= 0) {
1905                                 debug2("channel %d: closing read-efd %d",
1906                                     c->self, c->efd);
1907                                 channel_close_fd(&c->efd);
1908                         } else {
1909                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1910                                         debug3("channel %d: discard efd",
1911                                             c->self);
1912                                 } else
1913                                         buffer_append(&c->extended, buf, len);
1914                         }
1915                 }
1916         }
1917         return 1;
1918 }
1919
1920 static int
1921 channel_check_window(Channel *c)
1922 {
1923         if (c->type == SSH_CHANNEL_OPEN &&
1924             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1925             ((c->local_window_max - c->local_window >
1926             c->local_maxpacket*3) ||
1927             c->local_window < c->local_window_max/2) &&
1928             c->local_consumed > 0) {
1929                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1930                 packet_put_int(c->remote_id);
1931                 packet_put_int(c->local_consumed);
1932                 packet_send();
1933                 debug2("channel %d: window %d sent adjust %d",
1934                     c->self, c->local_window,
1935                     c->local_consumed);
1936                 c->local_window += c->local_consumed;
1937                 c->local_consumed = 0;
1938         }
1939         return 1;
1940 }
1941
1942 static void
1943 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1944 {
1945         channel_handle_rfd(c, readset, writeset);
1946         channel_handle_wfd(c, readset, writeset);
1947         if (!compat20)
1948                 return;
1949         channel_handle_efd(c, readset, writeset);
1950         channel_check_window(c);
1951 }
1952
1953 static u_int
1954 read_mux(Channel *c, u_int need)
1955 {
1956         char buf[CHAN_RBUF];
1957         int len;
1958         u_int rlen;
1959
1960         if (buffer_len(&c->input) < need) {
1961                 rlen = need - buffer_len(&c->input);
1962                 len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
1963                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1964                         return buffer_len(&c->input);
1965                 if (len <= 0) {
1966                         debug2("channel %d: ctl read<=0 rfd %d len %d",
1967                             c->self, c->rfd, len);
1968                         chan_read_failed(c);
1969                         return 0;
1970                 } else
1971                         buffer_append(&c->input, buf, len);
1972         }
1973         return buffer_len(&c->input);
1974 }
1975
1976 static void
1977 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1978 {
1979         u_int need;
1980         ssize_t len;
1981
1982         if (!compat20)
1983                 fatal("%s: entered with !compat20", __func__);
1984
1985         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1986             (c->istate == CHAN_INPUT_OPEN ||
1987             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1988                 /*
1989                  * Don't not read past the precise end of packets to
1990                  * avoid disrupting fd passing.
1991                  */
1992                 if (read_mux(c, 4) < 4) /* read header */
1993                         return;
1994                 need = get_u32(buffer_ptr(&c->input));
1995 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1996                 if (need > CHANNEL_MUX_MAX_PACKET) {
1997                         debug2("channel %d: packet too big %u > %u",
1998                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1999                         chan_rcvd_oclose(c);
2000                         return;
2001                 }
2002                 if (read_mux(c, need + 4) < need + 4) /* read body */
2003                         return;
2004                 if (c->mux_rcb(c) != 0) {
2005                         debug("channel %d: mux_rcb failed", c->self);
2006                         chan_mark_dead(c);
2007                         return;
2008                 }
2009         }
2010
2011         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
2012             buffer_len(&c->output) > 0) {
2013                 len = write(c->wfd, buffer_ptr(&c->output),
2014                     buffer_len(&c->output));
2015                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
2016                         return;
2017                 if (len <= 0) {
2018                         chan_mark_dead(c);
2019                         return;
2020                 }
2021                 buffer_consume(&c->output, len);
2022         }
2023 }
2024
2025 static void
2026 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
2027 {
2028         Channel *nc;
2029         struct sockaddr_storage addr;
2030         socklen_t addrlen;
2031         int newsock;
2032         uid_t euid;
2033         gid_t egid;
2034
2035         if (!FD_ISSET(c->sock, readset))
2036                 return;
2037
2038         debug("multiplexing control connection");
2039
2040         /*
2041          * Accept connection on control socket
2042          */
2043         memset(&addr, 0, sizeof(addr));
2044         addrlen = sizeof(addr);
2045         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
2046             &addrlen)) == -1) {
2047                 error("%s accept: %s", __func__, strerror(errno));
2048                 if (errno == EMFILE || errno == ENFILE)
2049                         c->notbefore = monotime() + 1;
2050                 return;
2051         }
2052
2053         if (getpeereid(newsock, &euid, &egid) < 0) {
2054                 error("%s getpeereid failed: %s", __func__,
2055                     strerror(errno));
2056                 close(newsock);
2057                 return;
2058         }
2059         if ((euid != 0) && (getuid() != euid)) {
2060                 error("multiplex uid mismatch: peer euid %u != uid %u",
2061                     (u_int)euid, (u_int)getuid());
2062                 close(newsock);
2063                 return;
2064         }
2065         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
2066             newsock, newsock, -1, c->local_window_max,
2067             c->local_maxpacket, 0, "mux-control", 1);
2068         nc->mux_rcb = c->mux_rcb;
2069         debug3("%s: new mux channel %d fd %d", __func__,
2070             nc->self, nc->sock);
2071         /* establish state */
2072         nc->mux_rcb(nc);
2073         /* mux state transitions must not elicit protocol messages */
2074         nc->flags |= CHAN_LOCAL;
2075 }
2076
2077 /* ARGSUSED */
2078 static void
2079 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
2080 {
2081         int len;
2082
2083         /* Send buffered output data to the socket. */
2084         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2085                 len = write(c->sock, buffer_ptr(&c->output),
2086                             buffer_len(&c->output));
2087                 if (len <= 0)
2088                         buffer_clear(&c->output);
2089                 else
2090                         buffer_consume(&c->output, len);
2091         }
2092 }
2093
2094 static void
2095 channel_handler_init_20(void)
2096 {
2097         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2098         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2099         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2100         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2101         channel_pre[SSH_CHANNEL_UNIX_LISTENER] =        &channel_pre_listener;
2102         channel_pre[SSH_CHANNEL_RUNIX_LISTENER] =       &channel_pre_listener;
2103         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2104         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2105         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2106         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2107         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2108         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2109
2110         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2111         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2112         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2113         channel_post[SSH_CHANNEL_UNIX_LISTENER] =       &channel_post_port_listener;
2114         channel_post[SSH_CHANNEL_RUNIX_LISTENER] =      &channel_post_port_listener;
2115         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2116         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2117         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2118         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2119         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2120         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2121 }
2122
2123 static void
2124 channel_handler_init_13(void)
2125 {
2126         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2127         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2128         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2129         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2130         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2131         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2132         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2133         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2134         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2135
2136         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2137         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2138         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2139         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2140         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2141         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2142         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2143 }
2144
2145 static void
2146 channel_handler_init_15(void)
2147 {
2148         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2149         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2150         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2151         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2152         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2153         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2154         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2155
2156         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2157         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2158         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2159         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2160         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2161         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2162 }
2163
2164 static void
2165 channel_handler_init(void)
2166 {
2167         int i;
2168
2169         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2170                 channel_pre[i] = NULL;
2171                 channel_post[i] = NULL;
2172         }
2173         if (compat20)
2174                 channel_handler_init_20();
2175         else if (compat13)
2176                 channel_handler_init_13();
2177         else
2178                 channel_handler_init_15();
2179 }
2180
2181 /* gc dead channels */
2182 static void
2183 channel_garbage_collect(Channel *c)
2184 {
2185         if (c == NULL)
2186                 return;
2187         if (c->detach_user != NULL) {
2188                 if (!chan_is_dead(c, c->detach_close))
2189                         return;
2190                 debug2("channel %d: gc: notify user", c->self);
2191                 c->detach_user(c->self, NULL);
2192                 /* if we still have a callback */
2193                 if (c->detach_user != NULL)
2194                         return;
2195                 debug2("channel %d: gc: user detached", c->self);
2196         }
2197         if (!chan_is_dead(c, 1))
2198                 return;
2199         debug2("channel %d: garbage collecting", c->self);
2200         channel_free(c);
2201 }
2202
2203 static void
2204 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2205     time_t *unpause_secs)
2206 {
2207         static int did_init = 0;
2208         u_int i, oalloc;
2209         Channel *c;
2210         time_t now;
2211
2212         if (!did_init) {
2213                 channel_handler_init();
2214                 did_init = 1;
2215         }
2216         now = monotime();
2217         if (unpause_secs != NULL)
2218                 *unpause_secs = 0;
2219         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2220                 c = channels[i];
2221                 if (c == NULL)
2222                         continue;
2223                 if (c->delayed) {
2224                         if (ftab == channel_pre)
2225                                 c->delayed = 0;
2226                         else
2227                                 continue;
2228                 }
2229                 if (ftab[c->type] != NULL) {
2230                         /*
2231                          * Run handlers that are not paused.
2232                          */
2233                         if (c->notbefore <= now)
2234                                 (*ftab[c->type])(c, readset, writeset);
2235                         else if (unpause_secs != NULL) {
2236                                 /*
2237                                  * Collect the time that the earliest
2238                                  * channel comes off pause.
2239                                  */
2240                                 debug3("%s: chan %d: skip for %d more seconds",
2241                                     __func__, c->self,
2242                                     (int)(c->notbefore - now));
2243                                 if (*unpause_secs == 0 ||
2244                                     (c->notbefore - now) < *unpause_secs)
2245                                         *unpause_secs = c->notbefore - now;
2246                         }
2247                 }
2248                 channel_garbage_collect(c);
2249         }
2250         if (unpause_secs != NULL && *unpause_secs != 0)
2251                 debug3("%s: first channel unpauses in %d seconds",
2252                     __func__, (int)*unpause_secs);
2253 }
2254
2255 /*
2256  * Allocate/update select bitmasks and add any bits relevant to channels in
2257  * select bitmasks.
2258  */
2259 void
2260 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2261     u_int *nallocp, time_t *minwait_secs, int rekeying)
2262 {
2263         u_int n, sz, nfdset;
2264
2265         n = MAXIMUM(*maxfdp, channel_max_fd);
2266
2267         nfdset = howmany(n+1, NFDBITS);
2268         /* Explicitly test here, because xrealloc isn't always called */
2269         if (nfdset && SIZE_MAX / nfdset < sizeof(fd_mask))
2270                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2271         sz = nfdset * sizeof(fd_mask);
2272
2273         /* perhaps check sz < nalloc/2 and shrink? */
2274         if (*readsetp == NULL || sz > *nallocp) {
2275                 *readsetp = xreallocarray(*readsetp, nfdset, sizeof(fd_mask));
2276                 *writesetp = xreallocarray(*writesetp, nfdset, sizeof(fd_mask));
2277                 *nallocp = sz;
2278         }
2279         *maxfdp = n;
2280         memset(*readsetp, 0, sz);
2281         memset(*writesetp, 0, sz);
2282
2283         if (!rekeying)
2284                 channel_handler(channel_pre, *readsetp, *writesetp,
2285                     minwait_secs);
2286 }
2287
2288 /*
2289  * After select, perform any appropriate operations for channels which have
2290  * events pending.
2291  */
2292 void
2293 channel_after_select(fd_set *readset, fd_set *writeset)
2294 {
2295         channel_handler(channel_post, readset, writeset, NULL);
2296 }
2297
2298
2299 /* If there is data to send to the connection, enqueue some of it now. */
2300 void
2301 channel_output_poll(void)
2302 {
2303         Channel *c;
2304         u_int i, len;
2305
2306         for (i = 0; i < channels_alloc; i++) {
2307                 c = channels[i];
2308                 if (c == NULL)
2309                         continue;
2310
2311                 /*
2312                  * We are only interested in channels that can have buffered
2313                  * incoming data.
2314                  */
2315                 if (compat13) {
2316                         if (c->type != SSH_CHANNEL_OPEN &&
2317                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2318                                 continue;
2319                 } else {
2320                         if (c->type != SSH_CHANNEL_OPEN)
2321                                 continue;
2322                 }
2323                 if (compat20 &&
2324                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2325                         /* XXX is this true? */
2326                         debug3("channel %d: will not send data after close", c->self);
2327                         continue;
2328                 }
2329
2330                 /* Get the amount of buffered data for this channel. */
2331                 if ((c->istate == CHAN_INPUT_OPEN ||
2332                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2333                     (len = buffer_len(&c->input)) > 0) {
2334                         if (c->datagram) {
2335                                 if (len > 0) {
2336                                         u_char *data;
2337                                         u_int dlen;
2338
2339                                         data = buffer_get_string(&c->input,
2340                                             &dlen);
2341                                         if (dlen > c->remote_window ||
2342                                             dlen > c->remote_maxpacket) {
2343                                                 debug("channel %d: datagram "
2344                                                     "too big for channel",
2345                                                     c->self);
2346                                                 free(data);
2347                                                 continue;
2348                                         }
2349                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2350                                         packet_put_int(c->remote_id);
2351                                         packet_put_string(data, dlen);
2352                                         packet_send();
2353                                         c->remote_window -= dlen;
2354                                         free(data);
2355                                 }
2356                                 continue;
2357                         }
2358                         /*
2359                          * Send some data for the other side over the secure
2360                          * connection.
2361                          */
2362                         if (compat20) {
2363                                 if (len > c->remote_window)
2364                                         len = c->remote_window;
2365                                 if (len > c->remote_maxpacket)
2366                                         len = c->remote_maxpacket;
2367                         } else {
2368                                 if (packet_is_interactive()) {
2369                                         if (len > 1024)
2370                                                 len = 512;
2371                                 } else {
2372                                         /* Keep the packets at reasonable size. */
2373                                         if (len > packet_get_maxsize()/2)
2374                                                 len = packet_get_maxsize()/2;
2375                                 }
2376                         }
2377                         if (len > 0) {
2378                                 packet_start(compat20 ?
2379                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2380                                 packet_put_int(c->remote_id);
2381                                 packet_put_string(buffer_ptr(&c->input), len);
2382                                 packet_send();
2383                                 buffer_consume(&c->input, len);
2384                                 c->remote_window -= len;
2385                         }
2386                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2387                         if (compat13)
2388                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2389                         /*
2390                          * input-buffer is empty and read-socket shutdown:
2391                          * tell peer, that we will not send more data: send IEOF.
2392                          * hack for extended data: delay EOF if EFD still in use.
2393                          */
2394                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2395                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2396                                     c->self, c->efd, buffer_len(&c->extended));
2397                         else
2398                                 chan_ibuf_empty(c);
2399                 }
2400                 /* Send extended data, i.e. stderr */
2401                 if (compat20 &&
2402                     !(c->flags & CHAN_EOF_SENT) &&
2403                     c->remote_window > 0 &&
2404                     (len = buffer_len(&c->extended)) > 0 &&
2405                     c->extended_usage == CHAN_EXTENDED_READ) {
2406                         debug2("channel %d: rwin %u elen %u euse %d",
2407                             c->self, c->remote_window, buffer_len(&c->extended),
2408                             c->extended_usage);
2409                         if (len > c->remote_window)
2410                                 len = c->remote_window;
2411                         if (len > c->remote_maxpacket)
2412                                 len = c->remote_maxpacket;
2413                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2414                         packet_put_int(c->remote_id);
2415                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2416                         packet_put_string(buffer_ptr(&c->extended), len);
2417                         packet_send();
2418                         buffer_consume(&c->extended, len);
2419                         c->remote_window -= len;
2420                         debug2("channel %d: sent ext data %d", c->self, len);
2421                 }
2422         }
2423 }
2424
2425 /* -- mux proxy support  */
2426
2427 /*
2428  * When multiplexing channel messages for mux clients we have to deal
2429  * with downstream messages from the mux client and upstream messages
2430  * from the ssh server:
2431  * 1) Handling downstream messages is straightforward and happens
2432  *    in channel_proxy_downstream():
2433  *    - We forward all messages (mostly) unmodified to the server.
2434  *    - However, in order to route messages from upstream to the correct
2435  *      downstream client, we have to replace the channel IDs used by the
2436  *      mux clients with a unique channel ID because the mux clients might
2437  *      use conflicting channel IDs.
2438  *    - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and
2439  *      SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local
2440  *      SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID
2441  *      with the newly allocated channel ID.
2442  * 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY
2443  *    channels and procesed by channel_proxy_upstream(). The local channel ID
2444  *    is then translated back to the original mux client ID.
2445  * 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE
2446  *    messages so we can clean up SSH_CHANNEL_MUX_PROXY channels.
2447  * 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the
2448  *    downstream mux client are removed.
2449  * 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server
2450  *    requires more work, because they are not addressed to a specific
2451  *    channel. E.g. client_request_forwarded_tcpip() needs to figure
2452  *    out whether the request is addressed to the local client or a
2453  *    specific downstream client based on the listen-address/port.
2454  * 6) Agent and X11-Forwarding have a similar problem and are currenly
2455  *    not supported as the matching session/channel cannot be identified
2456  *    easily.
2457  */
2458
2459 /*
2460  * receive packets from downstream mux clients:
2461  * channel callback fired on read from mux client, creates
2462  * SSH_CHANNEL_MUX_PROXY channels and translates channel IDs
2463  * on channel creation.
2464  */
2465 int
2466 channel_proxy_downstream(Channel *downstream)
2467 {
2468         Channel *c = NULL;
2469         struct ssh *ssh = active_state;
2470         struct sshbuf *original = NULL, *modified = NULL;
2471         const u_char *cp;
2472         char *ctype = NULL, *listen_host = NULL;
2473         u_char type;
2474         size_t have;
2475         int ret = -1, r, idx;
2476         u_int id, remote_id, listen_port;
2477
2478         /* sshbuf_dump(&downstream->input, stderr); */
2479         if ((r = sshbuf_get_string_direct(&downstream->input, &cp, &have))
2480             != 0) {
2481                 error("%s: malformed message: %s", __func__, ssh_err(r));
2482                 return -1;
2483         }
2484         if (have < 2) {
2485                 error("%s: short message", __func__);
2486                 return -1;
2487         }
2488         type = cp[1];
2489         /* skip padlen + type */
2490         cp += 2;
2491         have -= 2;
2492         if (ssh_packet_log_type(type))
2493                 debug3("%s: channel %u: down->up: type %u", __func__,
2494                     downstream->self, type);
2495
2496         switch (type) {
2497         case SSH2_MSG_CHANNEL_OPEN:
2498                 if ((original = sshbuf_from(cp, have)) == NULL ||
2499                     (modified = sshbuf_new()) == NULL) {
2500                         error("%s: alloc", __func__);
2501                         goto out;
2502                 }
2503                 if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 ||
2504                     (r = sshbuf_get_u32(original, &id)) != 0) {
2505                         error("%s: parse error %s", __func__, ssh_err(r));
2506                         goto out;
2507                 }
2508                 c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
2509                    -1, -1, -1, 0, 0, 0, ctype, 1);
2510                 c->mux_ctx = downstream;        /* point to mux client */
2511                 c->mux_downstream_id = id;      /* original downstream id */
2512                 if ((r = sshbuf_put_cstring(modified, ctype)) != 0 ||
2513                     (r = sshbuf_put_u32(modified, c->self)) != 0 ||
2514                     (r = sshbuf_putb(modified, original)) != 0) {
2515                         error("%s: compose error %s", __func__, ssh_err(r));
2516                         channel_free(c);
2517                         goto out;
2518                 }
2519                 break;
2520         case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
2521                 /*
2522                  * Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we
2523                  * need to parse 'remote_id' instead of 'ctype'.
2524                  */
2525                 if ((original = sshbuf_from(cp, have)) == NULL ||
2526                     (modified = sshbuf_new()) == NULL) {
2527                         error("%s: alloc", __func__);
2528                         goto out;
2529                 }
2530                 if ((r = sshbuf_get_u32(original, &remote_id)) != 0 ||
2531                     (r = sshbuf_get_u32(original, &id)) != 0) {
2532                         error("%s: parse error %s", __func__, ssh_err(r));
2533                         goto out;
2534                 }
2535                 c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
2536                    -1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
2537                 c->mux_ctx = downstream;        /* point to mux client */
2538                 c->mux_downstream_id = id;
2539                 c->remote_id = remote_id;
2540                 if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
2541                     (r = sshbuf_put_u32(modified, c->self)) != 0 ||
2542                     (r = sshbuf_putb(modified, original)) != 0) {
2543                         error("%s: compose error %s", __func__, ssh_err(r));
2544                         channel_free(c);
2545                         goto out;
2546                 }
2547                 break;
2548         case SSH2_MSG_GLOBAL_REQUEST:
2549                 if ((original = sshbuf_from(cp, have)) == NULL) {
2550                         error("%s: alloc", __func__);
2551                         goto out;
2552                 }
2553                 if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) {
2554                         error("%s: parse error %s", __func__, ssh_err(r));
2555                         goto out;
2556                 }
2557                 if (strcmp(ctype, "tcpip-forward") != 0) {
2558                         error("%s: unsupported request %s", __func__, ctype);
2559                         goto out;
2560                 }
2561                 if ((r = sshbuf_get_u8(original, NULL)) != 0 ||
2562                     (r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 ||
2563                     (r = sshbuf_get_u32(original, &listen_port)) != 0) {
2564                         error("%s: parse error %s", __func__, ssh_err(r));
2565                         goto out;
2566                 }
2567                 if (listen_port > 65535) {
2568                         error("%s: tcpip-forward for %s: bad port %u",
2569                             __func__, listen_host, listen_port);
2570                         goto out;
2571                 }
2572                 /* Record that connection to this host/port is permitted. */
2573                 permitted_opens = xreallocarray(permitted_opens,
2574                     num_permitted_opens + 1, sizeof(*permitted_opens));
2575                 idx = num_permitted_opens++;
2576                 permitted_opens[idx].host_to_connect = xstrdup("<mux>");
2577                 permitted_opens[idx].port_to_connect = -1;
2578                 permitted_opens[idx].listen_host = listen_host;
2579                 permitted_opens[idx].listen_port = (int)listen_port;
2580                 permitted_opens[idx].downstream = downstream;
2581                 listen_host = NULL;
2582                 break;
2583         case SSH2_MSG_CHANNEL_CLOSE:
2584                 if (have < 4)
2585                         break;
2586                 remote_id = PEEK_U32(cp);
2587                 if ((c = channel_by_remote_id(remote_id)) != NULL) {
2588                         if (c->flags & CHAN_CLOSE_RCVD)
2589                                 channel_free(c);
2590                         else
2591                                 c->flags |= CHAN_CLOSE_SENT;
2592                 }
2593                 break;
2594         }
2595         if (modified) {
2596                 if ((r = sshpkt_start(ssh, type)) != 0 ||
2597                     (r = sshpkt_putb(ssh, modified)) != 0 ||
2598                     (r = sshpkt_send(ssh)) != 0) {
2599                         error("%s: send %s", __func__, ssh_err(r));
2600                         goto out;
2601                 }
2602         } else {
2603                 if ((r = sshpkt_start(ssh, type)) != 0 ||
2604                     (r = sshpkt_put(ssh, cp, have)) != 0 ||
2605                     (r = sshpkt_send(ssh)) != 0) {
2606                         error("%s: send %s", __func__, ssh_err(r));
2607                         goto out;
2608                 }
2609         }
2610         ret = 0;
2611  out:
2612         free(ctype);
2613         free(listen_host);
2614         sshbuf_free(original);
2615         sshbuf_free(modified);
2616         return ret;
2617 }
2618
2619 /*
2620  * receive packets from upstream server and de-multiplex packets
2621  * to correct downstream:
2622  * implemented as a helper for channel input handlers,
2623  * replaces local (proxy) channel ID with downstream channel ID.
2624  */
2625 int
2626 channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
2627 {
2628         struct ssh *ssh = active_state;
2629         struct sshbuf *b = NULL;
2630         Channel *downstream;
2631         const u_char *cp = NULL;
2632         size_t len;
2633         int r;
2634
2635         /*
2636          * When receiving packets from the peer we need to check whether we
2637          * need to forward the packets to the mux client. In this case we
2638          * restore the orignal channel id and keep track of CLOSE messages,
2639          * so we can cleanup the channel.
2640          */
2641         if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY)
2642                 return 0;
2643         if ((downstream = c->mux_ctx) == NULL)
2644                 return 0;
2645         switch (type) {
2646         case SSH2_MSG_CHANNEL_CLOSE:
2647         case SSH2_MSG_CHANNEL_DATA:
2648         case SSH2_MSG_CHANNEL_EOF:
2649         case SSH2_MSG_CHANNEL_EXTENDED_DATA:
2650         case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
2651         case SSH2_MSG_CHANNEL_OPEN_FAILURE:
2652         case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
2653         case SSH2_MSG_CHANNEL_SUCCESS:
2654         case SSH2_MSG_CHANNEL_FAILURE:
2655         case SSH2_MSG_CHANNEL_REQUEST:
2656                 break;
2657         default:
2658                 debug2("%s: channel %u: unsupported type %u", __func__,
2659                     c->self, type);
2660                 return 0;
2661         }
2662         if ((b = sshbuf_new()) == NULL) {
2663                 error("%s: alloc reply", __func__);
2664                 goto out;
2665         }
2666         /* get remaining payload (after id) */
2667         cp = sshpkt_ptr(ssh, &len);
2668         if (cp == NULL) {
2669                 error("%s: no packet", __func__);
2670                 goto out;
2671         }
2672         /* translate id and send to muxclient */
2673         if ((r = sshbuf_put_u8(b, 0)) != 0 ||   /* padlen */
2674             (r = sshbuf_put_u8(b, type)) != 0 ||
2675             (r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
2676             (r = sshbuf_put(b, cp, len)) != 0 ||
2677             (r = sshbuf_put_stringb(&downstream->output, b)) != 0) {
2678                 error("%s: compose for muxclient %s", __func__, ssh_err(r));
2679                 goto out;
2680         }
2681         /* sshbuf_dump(b, stderr); */
2682         if (ssh_packet_log_type(type))
2683                 debug3("%s: channel %u: up->down: type %u", __func__, c->self,
2684                     type);
2685  out:
2686         /* update state */
2687         switch (type) {
2688         case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
2689                 /* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
2690                 if (cp && len > 4)
2691                         c->remote_id = PEEK_U32(cp);
2692                 break;
2693         case SSH2_MSG_CHANNEL_CLOSE:
2694                 if (c->flags & CHAN_CLOSE_SENT)
2695                         channel_free(c);
2696                 else
2697                         c->flags |= CHAN_CLOSE_RCVD;
2698                 break;
2699         }
2700         sshbuf_free(b);
2701         return 1;
2702 }
2703
2704 /* -- protocol input */
2705
2706 /* ARGSUSED */
2707 int
2708 channel_input_data(int type, u_int32_t seq, void *ctxt)
2709 {
2710         int id;
2711         const u_char *data;
2712         u_int data_len, win_len;
2713         Channel *c;
2714
2715         /* Get the channel number and verify it. */
2716         id = packet_get_int();
2717         c = channel_lookup(id);
2718         if (c == NULL)
2719                 packet_disconnect("Received data for nonexistent channel %d.", id);
2720         if (channel_proxy_upstream(c, type, seq, ctxt))
2721                 return 0;
2722
2723         /* Ignore any data for non-open channels (might happen on close) */
2724         if (c->type != SSH_CHANNEL_OPEN &&
2725             c->type != SSH_CHANNEL_X11_OPEN)
2726                 return 0;
2727
2728         /* Get the data. */
2729         data = packet_get_string_ptr(&data_len);
2730         win_len = data_len;
2731         if (c->datagram)
2732                 win_len += 4;  /* string length header */
2733
2734         /*
2735          * Ignore data for protocol > 1.3 if output end is no longer open.
2736          * For protocol 2 the sending side is reducing its window as it sends
2737          * data, so we must 'fake' consumption of the data in order to ensure
2738          * that window updates are sent back.  Otherwise the connection might
2739          * deadlock.
2740          */
2741         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2742                 if (compat20) {
2743                         c->local_window -= win_len;
2744                         c->local_consumed += win_len;
2745                 }
2746                 return 0;
2747         }
2748
2749         if (compat20) {
2750                 if (win_len > c->local_maxpacket) {
2751                         logit("channel %d: rcvd big packet %d, maxpack %d",
2752                             c->self, win_len, c->local_maxpacket);
2753                 }
2754                 if (win_len > c->local_window) {
2755                         logit("channel %d: rcvd too much data %d, win %d",
2756                             c->self, win_len, c->local_window);
2757                         return 0;
2758                 }
2759                 c->local_window -= win_len;
2760         }
2761         if (c->datagram)
2762                 buffer_put_string(&c->output, data, data_len);
2763         else
2764                 buffer_append(&c->output, data, data_len);
2765         packet_check_eom();
2766         return 0;
2767 }
2768
2769 /* ARGSUSED */
2770 int
2771 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2772 {
2773         int id;
2774         char *data;
2775         u_int data_len, tcode;
2776         Channel *c;
2777
2778         /* Get the channel number and verify it. */
2779         id = packet_get_int();
2780         c = channel_lookup(id);
2781
2782         if (c == NULL)
2783                 packet_disconnect("Received extended_data for bad channel %d.", id);
2784         if (channel_proxy_upstream(c, type, seq, ctxt))
2785                 return 0;
2786         if (c->type != SSH_CHANNEL_OPEN) {
2787                 logit("channel %d: ext data for non open", id);
2788                 return 0;
2789         }
2790         if (c->flags & CHAN_EOF_RCVD) {
2791                 if (datafellows & SSH_BUG_EXTEOF)
2792                         debug("channel %d: accepting ext data after eof", id);
2793                 else
2794                         packet_disconnect("Received extended_data after EOF "
2795                             "on channel %d.", id);
2796         }
2797         tcode = packet_get_int();
2798         if (c->efd == -1 ||
2799             c->extended_usage != CHAN_EXTENDED_WRITE ||
2800             tcode != SSH2_EXTENDED_DATA_STDERR) {
2801                 logit("channel %d: bad ext data", c->self);
2802                 return 0;
2803         }
2804         data = packet_get_string(&data_len);
2805         packet_check_eom();
2806         if (data_len > c->local_window) {
2807                 logit("channel %d: rcvd too much extended_data %d, win %d",
2808                     c->self, data_len, c->local_window);
2809                 free(data);
2810                 return 0;
2811         }
2812         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2813         c->local_window -= data_len;
2814         buffer_append(&c->extended, data, data_len);
2815         free(data);
2816         return 0;
2817 }
2818
2819 /* ARGSUSED */
2820 int
2821 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2822 {
2823         int id;
2824         Channel *c;
2825
2826         id = packet_get_int();
2827         packet_check_eom();
2828         c = channel_lookup(id);
2829         if (c == NULL)
2830                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2831         if (channel_proxy_upstream(c, type, seq, ctxt))
2832                 return 0;
2833         chan_rcvd_ieof(c);
2834
2835         /* XXX force input close */
2836         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2837                 debug("channel %d: FORCE input drain", c->self);
2838                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2839                 if (buffer_len(&c->input) == 0)
2840                         chan_ibuf_empty(c);
2841         }
2842         return 0;
2843 }
2844
2845 /* ARGSUSED */
2846 int
2847 channel_input_close(int type, u_int32_t seq, void *ctxt)
2848 {
2849         int id;
2850         Channel *c;
2851
2852         id = packet_get_int();
2853         packet_check_eom();
2854         c = channel_lookup(id);
2855         if (c == NULL)
2856                 packet_disconnect("Received close for nonexistent channel %d.", id);
2857         if (channel_proxy_upstream(c, type, seq, ctxt))
2858                 return 0;
2859         /*
2860          * Send a confirmation that we have closed the channel and no more
2861          * data is coming for it.
2862          */
2863         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2864         packet_put_int(c->remote_id);
2865         packet_send();
2866
2867         /*
2868          * If the channel is in closed state, we have sent a close request,
2869          * and the other side will eventually respond with a confirmation.
2870          * Thus, we cannot free the channel here, because then there would be
2871          * no-one to receive the confirmation.  The channel gets freed when
2872          * the confirmation arrives.
2873          */
2874         if (c->type != SSH_CHANNEL_CLOSED) {
2875                 /*
2876                  * Not a closed channel - mark it as draining, which will
2877                  * cause it to be freed later.
2878                  */
2879                 buffer_clear(&c->input);
2880                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2881         }
2882         return 0;
2883 }
2884
2885 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2886 /* ARGSUSED */
2887 int
2888 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2889 {
2890         int id = packet_get_int();
2891         Channel *c = channel_lookup(id);
2892
2893         if (c == NULL)
2894                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2895         if (channel_proxy_upstream(c, type, seq, ctxt))
2896                 return 0;
2897         packet_check_eom();
2898         chan_rcvd_oclose(c);
2899         return 0;
2900 }
2901
2902 /* ARGSUSED */
2903 int
2904 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2905 {
2906         int id = packet_get_int();
2907         Channel *c = channel_lookup(id);
2908
2909         if (c == NULL)
2910                 packet_disconnect("Received close confirmation for "
2911                     "out-of-range channel %d.", id);
2912         if (channel_proxy_upstream(c, type, seq, ctxt))
2913                 return 0;
2914         packet_check_eom();
2915         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2916                 packet_disconnect("Received close confirmation for "
2917                     "non-closed channel %d (type %d).", id, c->type);
2918         channel_free(c);
2919         return 0;
2920 }
2921
2922 /* ARGSUSED */
2923 int
2924 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2925 {
2926         int id, remote_id;
2927         Channel *c;
2928
2929         id = packet_get_int();
2930         c = channel_lookup(id);
2931
2932         if (c==NULL)
2933                 packet_disconnect("Received open confirmation for "
2934                     "unknown channel %d.", id);
2935         if (channel_proxy_upstream(c, type, seq, ctxt))
2936                 return 0;
2937         if (c->type != SSH_CHANNEL_OPENING)
2938                 packet_disconnect("Received open confirmation for "
2939                     "non-opening channel %d.", id);
2940         remote_id = packet_get_int();
2941         /* Record the remote channel number and mark that the channel is now open. */
2942         c->remote_id = remote_id;
2943         c->type = SSH_CHANNEL_OPEN;
2944
2945         if (compat20) {
2946                 c->remote_window = packet_get_int();
2947                 c->remote_maxpacket = packet_get_int();
2948                 if (c->open_confirm) {
2949                         debug2("callback start");
2950                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2951                         debug2("callback done");
2952                 }
2953                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2954                     c->remote_window, c->remote_maxpacket);
2955         }
2956         packet_check_eom();
2957         return 0;
2958 }
2959
2960 static char *
2961 reason2txt(int reason)
2962 {
2963         switch (reason) {
2964         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2965                 return "administratively prohibited";
2966         case SSH2_OPEN_CONNECT_FAILED:
2967                 return "connect failed";
2968         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2969                 return "unknown channel type";
2970         case SSH2_OPEN_RESOURCE_SHORTAGE:
2971                 return "resource shortage";
2972         }
2973         return "unknown reason";
2974 }
2975
2976 /* ARGSUSED */
2977 int
2978 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2979 {
2980         int id, reason;
2981         char *msg = NULL, *lang = NULL;
2982         Channel *c;
2983
2984         id = packet_get_int();
2985         c = channel_lookup(id);
2986
2987         if (c==NULL)
2988                 packet_disconnect("Received open failure for "
2989                     "unknown channel %d.", id);
2990         if (channel_proxy_upstream(c, type, seq, ctxt))
2991                 return 0;
2992         if (c->type != SSH_CHANNEL_OPENING)
2993                 packet_disconnect("Received open failure for "
2994                     "non-opening channel %d.", id);
2995         if (compat20) {
2996                 reason = packet_get_int();
2997                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2998                         msg  = packet_get_string(NULL);
2999                         lang = packet_get_string(NULL);
3000                 }
3001                 logit("channel %d: open failed: %s%s%s", id,
3002                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
3003                 free(msg);
3004                 free(lang);
3005                 if (c->open_confirm) {
3006                         debug2("callback start");
3007                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
3008                         debug2("callback done");
3009                 }
3010         }
3011         packet_check_eom();
3012         /* Schedule the channel for cleanup/deletion. */
3013         chan_mark_dead(c);
3014         return 0;
3015 }
3016
3017 /* ARGSUSED */
3018 int
3019 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
3020 {
3021         Channel *c;
3022         int id;
3023         u_int adjust, tmp;
3024
3025         if (!compat20)
3026                 return 0;
3027
3028         /* Get the channel number and verify it. */
3029         id = packet_get_int();
3030         c = channel_lookup(id);
3031
3032         if (c == NULL) {
3033                 logit("Received window adjust for non-open channel %d.", id);
3034                 return 0;
3035         }
3036         if (channel_proxy_upstream(c, type, seq, ctxt))
3037                 return 0;
3038         adjust = packet_get_int();
3039         packet_check_eom();
3040         debug2("channel %d: rcvd adjust %u", id, adjust);
3041         if ((tmp = c->remote_window + adjust) < c->remote_window)
3042                 fatal("channel %d: adjust %u overflows remote window %u",
3043                     id, adjust, c->remote_window);
3044         c->remote_window = tmp;
3045         return 0;
3046 }
3047
3048 /* ARGSUSED */
3049 int
3050 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
3051 {
3052         Channel *c = NULL;
3053         u_short host_port;
3054         char *host, *originator_string;
3055         int remote_id;
3056
3057         remote_id = packet_get_int();
3058         host = packet_get_string(NULL);
3059         host_port = packet_get_int();
3060
3061         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3062                 originator_string = packet_get_string(NULL);
3063         } else {
3064                 originator_string = xstrdup("unknown (remote did not supply name)");
3065         }
3066         packet_check_eom();
3067         c = channel_connect_to_port(host, host_port,
3068             "connected socket", originator_string, NULL, NULL);
3069         free(originator_string);
3070         free(host);
3071         if (c == NULL) {
3072                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3073                 packet_put_int(remote_id);
3074                 packet_send();
3075         } else
3076                 c->remote_id = remote_id;
3077         return 0;
3078 }
3079
3080 /* ARGSUSED */
3081 int
3082 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
3083 {
3084         Channel *c;
3085         struct channel_confirm *cc;
3086         int id;
3087
3088         /* Reset keepalive timeout */
3089         packet_set_alive_timeouts(0);
3090
3091         id = packet_get_int();
3092         debug2("channel_input_status_confirm: type %d id %d", type, id);
3093
3094         if ((c = channel_lookup(id)) == NULL) {
3095                 logit("channel_input_status_confirm: %d: unknown", id);
3096                 return 0;
3097         }
3098         if (channel_proxy_upstream(c, type, seq, ctxt))
3099                 return 0;
3100         packet_check_eom();
3101         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
3102                 return 0;
3103         cc->cb(type, c, cc->ctx);
3104         TAILQ_REMOVE(&c->status_confirms, cc, entry);
3105         explicit_bzero(cc, sizeof(*cc));
3106         free(cc);
3107         return 0;
3108 }
3109
3110 /* -- tcp forwarding */
3111
3112 void
3113 channel_set_af(int af)
3114 {
3115         IPv4or6 = af;
3116 }
3117
3118
3119 /*
3120  * Determine whether or not a port forward listens to loopback, the
3121  * specified address or wildcard. On the client, a specified bind
3122  * address will always override gateway_ports. On the server, a
3123  * gateway_ports of 1 (``yes'') will override the client's specification
3124  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
3125  * will bind to whatever address the client asked for.
3126  *
3127  * Special-case listen_addrs are:
3128  *
3129  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
3130  * "" (empty string), "*"  -> wildcard v4/v6
3131  * "localhost"             -> loopback v4/v6
3132  * "127.0.0.1" / "::1"     -> accepted even if gateway_ports isn't set
3133  */
3134 static const char *
3135 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
3136     int is_client, struct ForwardOptions *fwd_opts)
3137 {
3138         const char *addr = NULL;
3139         int wildcard = 0;
3140
3141         if (listen_addr == NULL) {
3142                 /* No address specified: default to gateway_ports setting */
3143                 if (fwd_opts->gateway_ports)
3144                         wildcard = 1;
3145         } else if (fwd_opts->gateway_ports || is_client) {
3146                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
3147                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
3148                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
3149                     (!is_client && fwd_opts->gateway_ports == 1)) {
3150                         wildcard = 1;
3151                         /*
3152                          * Notify client if they requested a specific listen
3153                          * address and it was overridden.
3154                          */
3155                         if (*listen_addr != '\0' &&
3156                             strcmp(listen_addr, "0.0.0.0") != 0 &&
3157                             strcmp(listen_addr, "*") != 0) {
3158                                 packet_send_debug("Forwarding listen address "
3159                                     "\"%s\" overridden by server "
3160                                     "GatewayPorts", listen_addr);
3161                         }
3162                 } else if (strcmp(listen_addr, "localhost") != 0 ||
3163                     strcmp(listen_addr, "127.0.0.1") == 0 ||
3164                     strcmp(listen_addr, "::1") == 0) {
3165                         /* Accept localhost address when GatewayPorts=yes */
3166                         addr = listen_addr;
3167                 }
3168         } else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
3169             strcmp(listen_addr, "::1") == 0) {
3170                 /*
3171                  * If a specific IPv4/IPv6 localhost address has been
3172                  * requested then accept it even if gateway_ports is in
3173                  * effect. This allows the client to prefer IPv4 or IPv6.
3174                  */
3175                 addr = listen_addr;
3176         }
3177         if (wildcardp != NULL)
3178                 *wildcardp = wildcard;
3179         return addr;
3180 }
3181
3182 static int
3183 channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
3184     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
3185 {
3186         Channel *c;
3187         int sock, r, success = 0, wildcard = 0, is_client;
3188         struct addrinfo hints, *ai, *aitop;
3189         const char *host, *addr;
3190         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3191         in_port_t *lport_p;
3192
3193         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
3194
3195         if (is_client && fwd->connect_path != NULL) {
3196                 host = fwd->connect_path;
3197         } else {
3198                 host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
3199                     fwd->listen_host : fwd->connect_host;
3200                 if (host == NULL) {
3201                         error("No forward host name.");
3202                         return 0;
3203                 }
3204                 if (strlen(host) >= NI_MAXHOST) {
3205                         error("Forward host name too long.");
3206                         return 0;
3207                 }
3208         }
3209
3210         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
3211         addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard,
3212             is_client, fwd_opts);
3213         debug3("%s: type %d wildcard %d addr %s", __func__,
3214             type, wildcard, (addr == NULL) ? "NULL" : addr);
3215
3216         /*
3217          * getaddrinfo returns a loopback address if the hostname is
3218          * set to NULL and hints.ai_flags is not AI_PASSIVE
3219          */
3220         memset(&hints, 0, sizeof(hints));
3221         hints.ai_family = IPv4or6;
3222         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
3223         hints.ai_socktype = SOCK_STREAM;
3224         snprintf(strport, sizeof strport, "%d", fwd->listen_port);
3225         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
3226                 if (addr == NULL) {
3227                         /* This really shouldn't happen */
3228                         packet_disconnect("getaddrinfo: fatal error: %s",
3229                             ssh_gai_strerror(r));
3230                 } else {
3231                         error("%s: getaddrinfo(%.64s): %s", __func__, addr,
3232                             ssh_gai_strerror(r));
3233                 }
3234                 return 0;
3235         }
3236         if (allocated_listen_port != NULL)
3237                 *allocated_listen_port = 0;
3238         for (ai = aitop; ai; ai = ai->ai_next) {
3239                 switch (ai->ai_family) {
3240                 case AF_INET:
3241                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
3242                             sin_port;
3243                         break;
3244                 case AF_INET6:
3245                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
3246                             sin6_port;
3247                         break;
3248                 default:
3249                         continue;
3250                 }
3251                 /*
3252                  * If allocating a port for -R forwards, then use the
3253                  * same port for all address families.
3254                  */
3255                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
3256                     allocated_listen_port != NULL && *allocated_listen_port > 0)
3257                         *lport_p = htons(*allocated_listen_port);
3258
3259                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
3260                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3261                         error("%s: getnameinfo failed", __func__);
3262                         continue;
3263                 }
3264                 /* Create a port to listen for the host. */
3265                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3266                 if (sock < 0) {
3267                         /* this is no error since kernel may not support ipv6 */
3268                         verbose("socket: %.100s", strerror(errno));
3269                         continue;
3270                 }
3271
3272                 channel_set_reuseaddr(sock);
3273                 if (ai->ai_family == AF_INET6)
3274                         sock_set_v6only(sock);
3275
3276                 debug("Local forwarding listening on %s port %s.",
3277                     ntop, strport);
3278
3279                 /* Bind the socket to the address. */
3280                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3281                         /* address can be in use ipv6 address is already bound */
3282                         if (!ai->ai_next)
3283                                 error("bind: %.100s", strerror(errno));
3284                         else
3285                                 verbose("bind: %.100s", strerror(errno));
3286
3287                         close(sock);
3288                         continue;
3289                 }
3290                 /* Start listening for connections on the socket. */
3291                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3292                         error("listen: %.100s", strerror(errno));
3293                         close(sock);
3294                         continue;
3295                 }
3296
3297                 /*
3298                  * fwd->listen_port == 0 requests a dynamically allocated port -
3299                  * record what we got.
3300                  */
3301                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
3302                     allocated_listen_port != NULL &&
3303                     *allocated_listen_port == 0) {
3304                         *allocated_listen_port = get_local_port(sock);
3305                         debug("Allocated listen port %d",
3306                             *allocated_listen_port);
3307                 }
3308
3309                 /* Allocate a channel number for the socket. */
3310                 c = channel_new("port listener", type, sock, sock, -1,
3311                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
3312                     0, "port listener", 1);
3313                 c->path = xstrdup(host);
3314                 c->host_port = fwd->connect_port;
3315                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
3316                 if (fwd->listen_port == 0 && allocated_listen_port != NULL &&
3317                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
3318                         c->listening_port = *allocated_listen_port;
3319                 else
3320                         c->listening_port = fwd->listen_port;
3321                 success = 1;
3322         }
3323         if (success == 0)
3324                 error("%s: cannot listen to port: %d", __func__,
3325                     fwd->listen_port);
3326         freeaddrinfo(aitop);
3327         return success;
3328 }
3329
3330 static int
3331 channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
3332     struct ForwardOptions *fwd_opts)
3333 {
3334         struct sockaddr_un sunaddr;
3335         const char *path;
3336         Channel *c;
3337         int port, sock;
3338         mode_t omask;
3339
3340         switch (type) {
3341         case SSH_CHANNEL_UNIX_LISTENER:
3342                 if (fwd->connect_path != NULL) {
3343                         if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) {
3344                                 error("Local connecting path too long: %s",
3345                                     fwd->connect_path);
3346                                 return 0;
3347                         }
3348                         path = fwd->connect_path;
3349                         port = PORT_STREAMLOCAL;
3350                 } else {
3351                         if (fwd->connect_host == NULL) {
3352                                 error("No forward host name.");
3353                                 return 0;
3354                         }
3355                         if (strlen(fwd->connect_host) >= NI_MAXHOST) {
3356                                 error("Forward host name too long.");
3357                                 return 0;
3358                         }
3359                         path = fwd->connect_host;
3360                         port = fwd->connect_port;
3361                 }
3362                 break;
3363         case SSH_CHANNEL_RUNIX_LISTENER:
3364                 path = fwd->listen_path;
3365                 port = PORT_STREAMLOCAL;
3366                 break;
3367         default:
3368                 error("%s: unexpected channel type %d", __func__, type);
3369                 return 0;
3370         }
3371
3372         if (fwd->listen_path == NULL) {
3373                 error("No forward path name.");
3374                 return 0;
3375         }
3376         if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) {
3377                 error("Local listening path too long: %s", fwd->listen_path);
3378                 return 0;
3379         }
3380
3381         debug3("%s: type %d path %s", __func__, type, fwd->listen_path);
3382
3383         /* Start a Unix domain listener. */
3384         omask = umask(fwd_opts->streamlocal_bind_mask);
3385         sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG,
3386             fwd_opts->streamlocal_bind_unlink);
3387         umask(omask);
3388         if (sock < 0)
3389                 return 0;
3390
3391         debug("Local forwarding listening on path %s.", fwd->listen_path);
3392
3393         /* Allocate a channel number for the socket. */
3394         c = channel_new("unix listener", type, sock, sock, -1,
3395             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
3396             0, "unix listener", 1);
3397         c->path = xstrdup(path);
3398         c->host_port = port;
3399         c->listening_port = PORT_STREAMLOCAL;
3400         c->listening_addr = xstrdup(fwd->listen_path);
3401         return 1;
3402 }
3403
3404 static int
3405 channel_cancel_rport_listener_tcpip(const char *host, u_short port)
3406 {
3407         u_int i;
3408         int found = 0;
3409
3410         for (i = 0; i < channels_alloc; i++) {
3411                 Channel *c = channels[i];
3412                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
3413                         continue;
3414                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
3415                         debug2("%s: close channel %d", __func__, i);
3416                         channel_free(c);
3417                         found = 1;
3418                 }
3419         }
3420
3421         return (found);
3422 }
3423
3424 static int
3425 channel_cancel_rport_listener_streamlocal(const char *path)
3426 {
3427         u_int i;
3428         int found = 0;
3429
3430         for (i = 0; i < channels_alloc; i++) {
3431                 Channel *c = channels[i];
3432                 if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
3433                         continue;
3434                 if (c->path == NULL)
3435                         continue;
3436                 if (strcmp(c->path, path) == 0) {
3437                         debug2("%s: close channel %d", __func__, i);
3438                         channel_free(c);
3439                         found = 1;
3440                 }
3441         }
3442
3443         return (found);
3444 }
3445
3446 int
3447 channel_cancel_rport_listener(struct Forward *fwd)
3448 {
3449         if (fwd->listen_path != NULL)
3450                 return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
3451         else
3452                 return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
3453 }
3454
3455 static int
3456 channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
3457     int cport, struct ForwardOptions *fwd_opts)
3458 {
3459         u_int i;
3460         int found = 0;
3461         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
3462
3463         for (i = 0; i < channels_alloc; i++) {
3464                 Channel *c = channels[i];
3465                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
3466                         continue;
3467                 if (c->listening_port != lport)
3468                         continue;
3469                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
3470                         /* skip dynamic forwardings */
3471                         if (c->host_port == 0)
3472                                 continue;
3473                 } else {
3474                         if (c->host_port != cport)
3475                                 continue;
3476                 }
3477                 if ((c->listening_addr == NULL && addr != NULL) ||
3478                     (c->listening_addr != NULL && addr == NULL))
3479                         continue;
3480                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
3481                         debug2("%s: close channel %d", __func__, i);
3482                         channel_free(c);
3483                         found = 1;
3484                 }
3485         }
3486
3487         return (found);
3488 }
3489
3490 static int
3491 channel_cancel_lport_listener_streamlocal(const char *path)
3492 {
3493         u_int i;
3494         int found = 0;
3495
3496         if (path == NULL) {
3497                 error("%s: no path specified.", __func__);
3498                 return 0;
3499         }
3500
3501         for (i = 0; i < channels_alloc; i++) {
3502                 Channel *c = channels[i];
3503                 if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
3504                         continue;
3505                 if (c->listening_addr == NULL)
3506                         continue;
3507                 if (strcmp(c->listening_addr, path) == 0) {
3508                         debug2("%s: close channel %d", __func__, i);
3509                         channel_free(c);
3510                         found = 1;
3511                 }
3512         }
3513
3514         return (found);
3515 }
3516
3517 int
3518 channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
3519 {
3520         if (fwd->listen_path != NULL)
3521                 return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
3522         else
3523                 return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
3524 }
3525
3526 /* protocol local port fwd, used by ssh (and sshd in v1) */
3527 int
3528 channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
3529 {
3530         if (fwd->listen_path != NULL) {
3531                 return channel_setup_fwd_listener_streamlocal(
3532                     SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
3533         } else {
3534                 return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
3535                     fwd, NULL, fwd_opts);
3536         }
3537 }
3538
3539 /* protocol v2 remote port fwd, used by sshd */
3540 int
3541 channel_setup_remote_fwd_listener(struct Forward *fwd,
3542     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
3543 {
3544         if (fwd->listen_path != NULL) {
3545                 return channel_setup_fwd_listener_streamlocal(
3546                     SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
3547         } else {
3548                 return channel_setup_fwd_listener_tcpip(
3549                     SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
3550                     fwd_opts);
3551         }
3552 }
3553
3554 /*
3555  * Translate the requested rfwd listen host to something usable for
3556  * this server.
3557  */
3558 static const char *
3559 channel_rfwd_bind_host(const char *listen_host)
3560 {
3561         if (listen_host == NULL) {
3562                 if (datafellows & SSH_BUG_RFWD_ADDR)
3563                         return "127.0.0.1";
3564                 else
3565                         return "localhost";
3566         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3567                 if (datafellows & SSH_BUG_RFWD_ADDR)
3568                         return "0.0.0.0";
3569                 else
3570                         return "";
3571         } else
3572                 return listen_host;
3573 }
3574
3575 /*
3576  * Initiate forwarding of connections to port "port" on remote host through
3577  * the secure channel to host:port from local side.
3578  * Returns handle (index) for updating the dynamic listen port with
3579  * channel_update_permitted_opens().
3580  */
3581 int
3582 channel_request_remote_forwarding(struct Forward *fwd)
3583 {
3584         int type, success = 0, idx = -1;
3585
3586         /* Send the forward request to the remote side. */
3587         if (compat20) {
3588                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3589                 if (fwd->listen_path != NULL) {
3590                     packet_put_cstring("streamlocal-forward@openssh.com");
3591                     packet_put_char(1);         /* boolean: want reply */
3592                     packet_put_cstring(fwd->listen_path);
3593                 } else {
3594                     packet_put_cstring("tcpip-forward");
3595                     packet_put_char(1);         /* boolean: want reply */
3596                     packet_put_cstring(channel_rfwd_bind_host(fwd->listen_host));
3597                     packet_put_int(fwd->listen_port);
3598                 }
3599                 packet_send();
3600                 packet_write_wait();
3601                 /* Assume that server accepts the request */
3602                 success = 1;
3603         } else if (fwd->listen_path == NULL) {
3604                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3605                 packet_put_int(fwd->listen_port);
3606                 packet_put_cstring(fwd->connect_host);
3607                 packet_put_int(fwd->connect_port);
3608                 packet_send();
3609                 packet_write_wait();
3610
3611                 /* Wait for response from the remote side. */
3612                 type = packet_read();
3613                 switch (type) {
3614                 case SSH_SMSG_SUCCESS:
3615                         success = 1;
3616                         break;
3617                 case SSH_SMSG_FAILURE:
3618                         break;
3619                 default:
3620                         /* Unknown packet */
3621                         packet_disconnect("Protocol error for port forward request:"
3622                             "received packet type %d.", type);
3623                 }
3624         } else {
3625                 logit("Warning: Server does not support remote stream local forwarding.");
3626         }
3627         if (success) {
3628                 /* Record that connection to this host/port is permitted. */
3629                 permitted_opens = xreallocarray(permitted_opens,
3630                     num_permitted_opens + 1, sizeof(*permitted_opens));
3631                 idx = num_permitted_opens++;
3632                 if (fwd->connect_path != NULL) {
3633                         permitted_opens[idx].host_to_connect =
3634                             xstrdup(fwd->connect_path);
3635                         permitted_opens[idx].port_to_connect =
3636                             PORT_STREAMLOCAL;
3637                 } else {
3638                         permitted_opens[idx].host_to_connect =
3639                             xstrdup(fwd->connect_host);
3640                         permitted_opens[idx].port_to_connect =
3641                             fwd->connect_port;
3642                 }
3643                 if (fwd->listen_path != NULL) {
3644                         permitted_opens[idx].listen_host = NULL;
3645                         permitted_opens[idx].listen_path =
3646                             xstrdup(fwd->listen_path);
3647                         permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
3648                 } else {
3649                         permitted_opens[idx].listen_host =
3650                             fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
3651                         permitted_opens[idx].listen_path = NULL;
3652                         permitted_opens[idx].listen_port = fwd->listen_port;
3653                 }
3654                 permitted_opens[idx].downstream = NULL;
3655         }
3656         return (idx);
3657 }
3658
3659 static int
3660 open_match(ForwardPermission *allowed_open, const char *requestedhost,
3661     int requestedport)
3662 {
3663         if (allowed_open->host_to_connect == NULL)
3664                 return 0;
3665         if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
3666             allowed_open->port_to_connect != requestedport)
3667                 return 0;
3668         if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 &&
3669             strcmp(allowed_open->host_to_connect, requestedhost) != 0)
3670                 return 0;
3671         return 1;
3672 }
3673
3674 /*
3675  * Note that in the listen host/port case
3676  * we don't support FWD_PERMIT_ANY_PORT and
3677  * need to translate between the configured-host (listen_host)
3678  * and what we've sent to the remote server (channel_rfwd_bind_host)
3679  */
3680 static int
3681 open_listen_match_tcpip(ForwardPermission *allowed_open,
3682     const char *requestedhost, u_short requestedport, int translate)
3683 {
3684         const char *allowed_host;
3685
3686         if (allowed_open->host_to_connect == NULL)
3687                 return 0;
3688         if (allowed_open->listen_port != requestedport)
3689                 return 0;
3690         if (!translate && allowed_open->listen_host == NULL &&
3691             requestedhost == NULL)
3692                 return 1;
3693         allowed_host = translate ?
3694             channel_rfwd_bind_host(allowed_open->listen_host) :
3695             allowed_open->listen_host;
3696         if (allowed_host == NULL ||
3697             strcmp(allowed_host, requestedhost) != 0)
3698                 return 0;
3699         return 1;
3700 }
3701
3702 static int
3703 open_listen_match_streamlocal(ForwardPermission *allowed_open,
3704     const char *requestedpath)
3705 {
3706         if (allowed_open->host_to_connect == NULL)
3707                 return 0;
3708         if (allowed_open->listen_port != PORT_STREAMLOCAL)
3709                 return 0;
3710         if (allowed_open->listen_path == NULL ||
3711             strcmp(allowed_open->listen_path, requestedpath) != 0)
3712                 return 0;
3713         return 1;
3714 }
3715
3716 /*
3717  * Request cancellation of remote forwarding of connection host:port from
3718  * local side.
3719  */
3720 static int
3721 channel_request_rforward_cancel_tcpip(const char *host, u_short port)
3722 {
3723         int i;
3724
3725         if (!compat20)
3726                 return -1;
3727
3728         for (i = 0; i < num_permitted_opens; i++) {
3729                 if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
3730                         break;
3731         }
3732         if (i >= num_permitted_opens) {
3733                 debug("%s: requested forward not found", __func__);
3734                 return -1;
3735         }
3736         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3737         packet_put_cstring("cancel-tcpip-forward");
3738         packet_put_char(0);
3739         packet_put_cstring(channel_rfwd_bind_host(host));
3740         packet_put_int(port);
3741         packet_send();
3742
3743         permitted_opens[i].listen_port = 0;
3744         permitted_opens[i].port_to_connect = 0;
3745         free(permitted_opens[i].host_to_connect);
3746         permitted_opens[i].host_to_connect = NULL;
3747         free(permitted_opens[i].listen_host);
3748         permitted_opens[i].listen_host = NULL;
3749         permitted_opens[i].listen_path = NULL;
3750         permitted_opens[i].downstream = NULL;
3751
3752         return 0;
3753 }
3754
3755 /*
3756  * Request cancellation of remote forwarding of Unix domain socket
3757  * path from local side.
3758  */
3759 static int
3760 channel_request_rforward_cancel_streamlocal(const char *path)
3761 {
3762         int i;
3763
3764         if (!compat20)
3765                 return -1;
3766
3767         for (i = 0; i < num_permitted_opens; i++) {
3768                 if (open_listen_match_streamlocal(&permitted_opens[i], path))
3769                         break;
3770         }
3771         if (i >= num_permitted_opens) {
3772                 debug("%s: requested forward not found", __func__);
3773                 return -1;
3774         }
3775         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3776         packet_put_cstring("cancel-streamlocal-forward@openssh.com");
3777         packet_put_char(0);
3778         packet_put_cstring(path);
3779         packet_send();
3780
3781         permitted_opens[i].listen_port = 0;
3782         permitted_opens[i].port_to_connect = 0;
3783         free(permitted_opens[i].host_to_connect);
3784         permitted_opens[i].host_to_connect = NULL;
3785         permitted_opens[i].listen_host = NULL;
3786         free(permitted_opens[i].listen_path);
3787         permitted_opens[i].listen_path = NULL;
3788         permitted_opens[i].downstream = NULL;
3789
3790         return 0;
3791 }
3792
3793 /*
3794  * Request cancellation of remote forwarding of a connection from local side.
3795  */
3796 int
3797 channel_request_rforward_cancel(struct Forward *fwd)
3798 {
3799         if (fwd->listen_path != NULL) {
3800                 return (channel_request_rforward_cancel_streamlocal(
3801                     fwd->listen_path));
3802         } else {
3803                 return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
3804                     fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
3805         }
3806 }
3807
3808 /*
3809  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3810  * usually called by the server, because the user could connect to any port
3811  * anyway, and the server has no way to know but to trust the client anyway.
3812  */
3813 void
3814 channel_permit_all_opens(void)
3815 {
3816         if (num_permitted_opens == 0)
3817                 all_opens_permitted = 1;
3818 }
3819
3820 void
3821 channel_add_permitted_opens(char *host, int port)
3822 {
3823         debug("allow port forwarding to host %s port %d", host, port);
3824
3825         permitted_opens = xreallocarray(permitted_opens,
3826             num_permitted_opens + 1, sizeof(*permitted_opens));
3827         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3828         permitted_opens[num_permitted_opens].port_to_connect = port;
3829         permitted_opens[num_permitted_opens].listen_host = NULL;
3830         permitted_opens[num_permitted_opens].listen_path = NULL;
3831         permitted_opens[num_permitted_opens].listen_port = 0;
3832         permitted_opens[num_permitted_opens].downstream = NULL;
3833         num_permitted_opens++;
3834
3835         all_opens_permitted = 0;
3836 }
3837
3838 /*
3839  * Update the listen port for a dynamic remote forward, after
3840  * the actual 'newport' has been allocated. If 'newport' < 0 is
3841  * passed then they entry will be invalidated.
3842  */
3843 void
3844 channel_update_permitted_opens(int idx, int newport)
3845 {
3846         if (idx < 0 || idx >= num_permitted_opens) {
3847                 debug("channel_update_permitted_opens: index out of range:"
3848                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3849                 return;
3850         }
3851         debug("%s allowed port %d for forwarding to host %s port %d",
3852             newport > 0 ? "Updating" : "Removing",
3853             newport,
3854             permitted_opens[idx].host_to_connect,
3855             permitted_opens[idx].port_to_connect);
3856         if (newport >= 0)  {
3857                 permitted_opens[idx].listen_port =
3858                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3859         } else {
3860                 permitted_opens[idx].listen_port = 0;
3861                 permitted_opens[idx].port_to_connect = 0;
3862                 free(permitted_opens[idx].host_to_connect);
3863                 permitted_opens[idx].host_to_connect = NULL;
3864                 free(permitted_opens[idx].listen_host);
3865                 permitted_opens[idx].listen_host = NULL;
3866                 free(permitted_opens[idx].listen_path);
3867                 permitted_opens[idx].listen_path = NULL;
3868         }
3869 }
3870
3871 int
3872 channel_add_adm_permitted_opens(char *host, int port)
3873 {
3874         debug("config allows port forwarding to host %s port %d", host, port);
3875
3876         permitted_adm_opens = xreallocarray(permitted_adm_opens,
3877             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3878         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3879              = xstrdup(host);
3880         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3881         permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
3882         permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
3883         permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
3884         return ++num_adm_permitted_opens;
3885 }
3886
3887 void
3888 channel_disable_adm_local_opens(void)
3889 {
3890         channel_clear_adm_permitted_opens();
3891         permitted_adm_opens = xcalloc(sizeof(*permitted_adm_opens), 1);
3892         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3893         num_adm_permitted_opens = 1;
3894 }
3895
3896 void
3897 channel_clear_permitted_opens(void)
3898 {
3899         int i;
3900
3901         for (i = 0; i < num_permitted_opens; i++) {
3902                 free(permitted_opens[i].host_to_connect);
3903                 free(permitted_opens[i].listen_host);
3904                 free(permitted_opens[i].listen_path);
3905         }
3906         free(permitted_opens);
3907         permitted_opens = NULL;
3908         num_permitted_opens = 0;
3909 }
3910
3911 void
3912 channel_clear_adm_permitted_opens(void)
3913 {
3914         int i;
3915
3916         for (i = 0; i < num_adm_permitted_opens; i++) {
3917                 free(permitted_adm_opens[i].host_to_connect);
3918                 free(permitted_adm_opens[i].listen_host);
3919                 free(permitted_adm_opens[i].listen_path);
3920         }
3921         free(permitted_adm_opens);
3922         permitted_adm_opens = NULL;
3923         num_adm_permitted_opens = 0;
3924 }
3925
3926 void
3927 channel_print_adm_permitted_opens(void)
3928 {
3929         int i;
3930
3931         printf("permitopen");
3932         if (num_adm_permitted_opens == 0) {
3933                 printf(" any\n");
3934                 return;
3935         }
3936         for (i = 0; i < num_adm_permitted_opens; i++)
3937                 if (permitted_adm_opens[i].host_to_connect == NULL)
3938                         printf(" none");
3939                 else
3940                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3941                             permitted_adm_opens[i].port_to_connect);
3942         printf("\n");
3943 }
3944
3945 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3946 int
3947 permitopen_port(const char *p)
3948 {
3949         int port;
3950
3951         if (strcmp(p, "*") == 0)
3952                 return FWD_PERMIT_ANY_PORT;
3953         if ((port = a2port(p)) > 0)
3954                 return port;
3955         return -1;
3956 }
3957
3958 /* Try to start non-blocking connect to next host in cctx list */
3959 static int
3960 connect_next(struct channel_connect *cctx)
3961 {
3962         int sock, saved_errno;
3963         struct sockaddr_un *sunaddr;
3964         char ntop[NI_MAXHOST], strport[MAXIMUM(NI_MAXSERV,sizeof(sunaddr->sun_path))];
3965
3966         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3967                 switch (cctx->ai->ai_family) {
3968                 case AF_UNIX:
3969                         /* unix:pathname instead of host:port */
3970                         sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr;
3971                         strlcpy(ntop, "unix", sizeof(ntop));
3972                         strlcpy(strport, sunaddr->sun_path, sizeof(strport));
3973                         break;
3974                 case AF_INET:
3975                 case AF_INET6:
3976                         if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3977                             ntop, sizeof(ntop), strport, sizeof(strport),
3978                             NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3979                                 error("connect_next: getnameinfo failed");
3980                                 continue;
3981                         }
3982                         break;
3983                 default:
3984                         continue;
3985                 }
3986                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3987                     cctx->ai->ai_protocol)) == -1) {
3988                         if (cctx->ai->ai_next == NULL)
3989                                 error("socket: %.100s", strerror(errno));
3990                         else
3991                                 verbose("socket: %.100s", strerror(errno));
3992                         continue;
3993                 }
3994                 if (set_nonblock(sock) == -1)
3995                         fatal("%s: set_nonblock(%d)", __func__, sock);
3996                 if (connect(sock, cctx->ai->ai_addr,
3997                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3998                         debug("connect_next: host %.100s ([%.100s]:%s): "
3999                             "%.100s", cctx->host, ntop, strport,
4000                             strerror(errno));
4001                         saved_errno = errno;
4002                         close(sock);
4003                         errno = saved_errno;
4004                         continue;       /* fail -- try next */
4005                 }
4006                 if (cctx->ai->ai_family != AF_UNIX)
4007                         set_nodelay(sock);
4008                 debug("connect_next: host %.100s ([%.100s]:%s) "
4009                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
4010                 cctx->ai = cctx->ai->ai_next;
4011                 return sock;
4012         }
4013         return -1;
4014 }
4015
4016 static void
4017 channel_connect_ctx_free(struct channel_connect *cctx)
4018 {
4019         free(cctx->host);
4020         if (cctx->aitop) {
4021                 if (cctx->aitop->ai_family == AF_UNIX)
4022                         free(cctx->aitop);
4023                 else
4024                         freeaddrinfo(cctx->aitop);
4025         }
4026         memset(cctx, 0, sizeof(*cctx));
4027 }
4028
4029 /*
4030  * Return CONNECTING channel to remote host:port or local socket path,
4031  * passing back the failure reason if appropriate.
4032  */
4033 static Channel *
4034 connect_to_reason(const char *name, int port, char *ctype, char *rname,
4035      int *reason, const char **errmsg)
4036 {
4037         struct addrinfo hints;
4038         int gaierr;
4039         int sock = -1;
4040         char strport[NI_MAXSERV];
4041         struct channel_connect cctx;
4042         Channel *c;
4043
4044         memset(&cctx, 0, sizeof(cctx));
4045
4046         if (port == PORT_STREAMLOCAL) {
4047                 struct sockaddr_un *sunaddr;
4048                 struct addrinfo *ai;
4049
4050                 if (strlen(name) > sizeof(sunaddr->sun_path)) {
4051                         error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
4052                         return (NULL);
4053                 }
4054
4055                 /*
4056                  * Fake up a struct addrinfo for AF_UNIX connections.
4057                  * channel_connect_ctx_free() must check ai_family
4058                  * and use free() not freeaddirinfo() for AF_UNIX.
4059                  */
4060                 ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr));
4061                 memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr));
4062                 ai->ai_addr = (struct sockaddr *)(ai + 1);
4063                 ai->ai_addrlen = sizeof(*sunaddr);
4064                 ai->ai_family = AF_UNIX;
4065                 ai->ai_socktype = SOCK_STREAM;
4066                 ai->ai_protocol = PF_UNSPEC;
4067                 sunaddr = (struct sockaddr_un *)ai->ai_addr;
4068                 sunaddr->sun_family = AF_UNIX;
4069                 strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
4070                 cctx.aitop = ai;
4071         } else {
4072                 memset(&hints, 0, sizeof(hints));
4073                 hints.ai_family = IPv4or6;
4074                 hints.ai_socktype = SOCK_STREAM;
4075                 snprintf(strport, sizeof strport, "%d", port);
4076                 if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop))
4077                     != 0) {
4078                         if (errmsg != NULL)
4079                                 *errmsg = ssh_gai_strerror(gaierr);
4080                         if (reason != NULL)
4081                                 *reason = SSH2_OPEN_CONNECT_FAILED;
4082                         error("connect_to %.100s: unknown host (%s)", name,
4083                             ssh_gai_strerror(gaierr));
4084                         return NULL;
4085                 }
4086         }
4087
4088         cctx.host = xstrdup(name);
4089         cctx.port = port;
4090         cctx.ai = cctx.aitop;
4091
4092         if ((sock = connect_next(&cctx)) == -1) {
4093                 error("connect to %.100s port %d failed: %s",
4094                     name, port, strerror(errno));
4095                 channel_connect_ctx_free(&cctx);
4096                 return NULL;
4097         }
4098         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
4099             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
4100         c->connect_ctx = cctx;
4101         return c;
4102 }
4103
4104 /* Return CONNECTING channel to remote host:port or local socket path */
4105 static Channel *
4106 connect_to(const char *name, int port, char *ctype, char *rname)
4107 {
4108         return connect_to_reason(name, port, ctype, rname, NULL, NULL);
4109 }
4110
4111 /*
4112  * returns either the newly connected channel or the downstream channel
4113  * that needs to deal with this connection.
4114  */
4115 Channel *
4116 channel_connect_by_listen_address(const char *listen_host,
4117     u_short listen_port, char *ctype, char *rname)
4118 {
4119         int i;
4120
4121         for (i = 0; i < num_permitted_opens; i++) {
4122                 if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
4123                     listen_port, 1)) {
4124                         if (permitted_opens[i].downstream)
4125                                 return permitted_opens[i].downstream;
4126                         return connect_to(
4127                             permitted_opens[i].host_to_connect,
4128                             permitted_opens[i].port_to_connect, ctype, rname);
4129                 }
4130         }
4131         error("WARNING: Server requests forwarding for unknown listen_port %d",
4132             listen_port);
4133         return NULL;
4134 }
4135
4136 Channel *
4137 channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
4138 {
4139         int i;
4140
4141         for (i = 0; i < num_permitted_opens; i++) {
4142                 if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
4143                         return connect_to(
4144                             permitted_opens[i].host_to_connect,
4145                             permitted_opens[i].port_to_connect, ctype, rname);
4146                 }
4147         }
4148         error("WARNING: Server requests forwarding for unknown path %.100s",
4149             path);
4150         return NULL;
4151 }
4152
4153 /* Check if connecting to that port is permitted and connect. */
4154 Channel *
4155 channel_connect_to_port(const char *host, u_short port, char *ctype,
4156     char *rname, int *reason, const char **errmsg)
4157 {
4158         int i, permit, permit_adm = 1;
4159
4160         permit = all_opens_permitted;
4161         if (!permit) {
4162                 for (i = 0; i < num_permitted_opens; i++)
4163                         if (open_match(&permitted_opens[i], host, port)) {
4164                                 permit = 1;
4165                                 break;
4166                         }
4167         }
4168
4169         if (num_adm_permitted_opens > 0) {
4170                 permit_adm = 0;
4171                 for (i = 0; i < num_adm_permitted_opens; i++)
4172                         if (open_match(&permitted_adm_opens[i], host, port)) {
4173                                 permit_adm = 1;
4174                                 break;
4175                         }
4176         }
4177
4178         if (!permit || !permit_adm) {
4179                 logit("Received request to connect to host %.100s port %d, "
4180                     "but the request was denied.", host, port);
4181                 if (reason != NULL)
4182                         *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
4183                 return NULL;
4184         }
4185         return connect_to_reason(host, port, ctype, rname, reason, errmsg);
4186 }
4187
4188 /* Check if connecting to that path is permitted and connect. */
4189 Channel *
4190 channel_connect_to_path(const char *path, char *ctype, char *rname)
4191 {
4192         int i, permit, permit_adm = 1;
4193
4194         permit = all_opens_permitted;
4195         if (!permit) {
4196                 for (i = 0; i < num_permitted_opens; i++)
4197                         if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
4198                                 permit = 1;
4199                                 break;
4200                         }
4201         }
4202
4203         if (num_adm_permitted_opens > 0) {
4204                 permit_adm = 0;
4205                 for (i = 0; i < num_adm_permitted_opens; i++)
4206                         if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
4207                                 permit_adm = 1;
4208                                 break;
4209                         }
4210         }
4211
4212         if (!permit || !permit_adm) {
4213                 logit("Received request to connect to path %.100s, "
4214                     "but the request was denied.", path);
4215                 return NULL;
4216         }
4217         return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
4218 }
4219
4220 void
4221 channel_send_window_changes(void)
4222 {
4223         u_int i;
4224         struct winsize ws;
4225
4226         for (i = 0; i < channels_alloc; i++) {
4227                 if (channels[i] == NULL || !channels[i]->client_tty ||
4228                     channels[i]->type != SSH_CHANNEL_OPEN)
4229                         continue;
4230                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
4231                         continue;
4232                 channel_request_start(i, "window-change", 0);
4233                 packet_put_int((u_int)ws.ws_col);
4234                 packet_put_int((u_int)ws.ws_row);
4235                 packet_put_int((u_int)ws.ws_xpixel);
4236                 packet_put_int((u_int)ws.ws_ypixel);
4237                 packet_send();
4238         }
4239 }
4240
4241 /* -- X11 forwarding */
4242
4243 /*
4244  * Creates an internet domain socket for listening for X11 connections.
4245  * Returns 0 and a suitable display number for the DISPLAY variable
4246  * stored in display_numberp , or -1 if an error occurs.
4247  */
4248 int
4249 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
4250     int single_connection, u_int *display_numberp, int **chanids)
4251 {
4252         Channel *nc = NULL;
4253         int display_number, sock;
4254         u_short port;
4255         struct addrinfo hints, *ai, *aitop;
4256         char strport[NI_MAXSERV];
4257         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
4258
4259         if (chanids == NULL)
4260                 return -1;
4261
4262         for (display_number = x11_display_offset;
4263             display_number < MAX_DISPLAYS;
4264             display_number++) {
4265                 port = 6000 + display_number;
4266                 memset(&hints, 0, sizeof(hints));
4267                 hints.ai_family = IPv4or6;
4268                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
4269                 hints.ai_socktype = SOCK_STREAM;
4270                 snprintf(strport, sizeof strport, "%d", port);
4271                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
4272                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
4273                         return -1;
4274                 }
4275                 for (ai = aitop; ai; ai = ai->ai_next) {
4276                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
4277                                 continue;
4278                         sock = socket(ai->ai_family, ai->ai_socktype,
4279                             ai->ai_protocol);
4280                         if (sock < 0) {
4281                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
4282 #ifdef EPFNOSUPPORT
4283                                     && (errno != EPFNOSUPPORT)
4284 #endif
4285                                     ) {
4286                                         error("socket: %.100s", strerror(errno));
4287                                         freeaddrinfo(aitop);
4288                                         return -1;
4289                                 } else {
4290                                         debug("x11_create_display_inet: Socket family %d not supported",
4291                                                  ai->ai_family);
4292                                         continue;
4293                                 }
4294                         }
4295                         if (ai->ai_family == AF_INET6)
4296                                 sock_set_v6only(sock);
4297                         if (x11_use_localhost)
4298                                 channel_set_reuseaddr(sock);
4299                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
4300                                 debug2("bind port %d: %.100s", port, strerror(errno));
4301                                 close(sock);
4302
4303                                 for (n = 0; n < num_socks; n++) {
4304                                         close(socks[n]);
4305                                 }
4306                                 num_socks = 0;
4307                                 break;
4308                         }
4309                         socks[num_socks++] = sock;
4310                         if (num_socks == NUM_SOCKS)
4311                                 break;
4312                 }
4313                 freeaddrinfo(aitop);
4314                 if (num_socks > 0)
4315                         break;
4316         }
4317         if (display_number >= MAX_DISPLAYS) {
4318                 error("Failed to allocate internet-domain X11 display socket.");
4319                 return -1;
4320         }
4321         /* Start listening for connections on the socket. */
4322         for (n = 0; n < num_socks; n++) {
4323                 sock = socks[n];
4324                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
4325                         error("listen: %.100s", strerror(errno));
4326                         close(sock);
4327                         return -1;
4328                 }
4329         }
4330
4331         /* Allocate a channel for each socket. */
4332         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
4333         for (n = 0; n < num_socks; n++) {
4334                 sock = socks[n];
4335                 nc = channel_new("x11 listener",
4336                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
4337                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
4338                     0, "X11 inet listener", 1);
4339                 nc->single_connection = single_connection;
4340                 (*chanids)[n] = nc->self;
4341         }
4342         (*chanids)[n] = -1;
4343
4344         /* Return the display number for the DISPLAY environment variable. */
4345         *display_numberp = display_number;
4346         return (0);
4347 }
4348
4349 static int
4350 connect_local_xsocket_path(const char *pathname)
4351 {
4352         int sock;
4353         struct sockaddr_un addr;
4354
4355         sock = socket(AF_UNIX, SOCK_STREAM, 0);
4356         if (sock < 0)
4357                 error("socket: %.100s", strerror(errno));
4358         memset(&addr, 0, sizeof(addr));
4359         addr.sun_family = AF_UNIX;
4360         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
4361         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
4362                 return sock;
4363         close(sock);
4364         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
4365         return -1;
4366 }
4367
4368 static int
4369 connect_local_xsocket(u_int dnr)
4370 {
4371         char buf[1024];
4372         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
4373         return connect_local_xsocket_path(buf);
4374 }
4375
4376 #ifdef __APPLE__
4377 static int
4378 is_path_to_xsocket(const char *display, char *path, size_t pathlen)
4379 {
4380         struct stat sbuf;
4381
4382         if (strlcpy(path, display, pathlen) >= pathlen) {
4383                 error("%s: display path too long", __func__);
4384                 return 0;
4385         }
4386         if (display[0] != '/')
4387                 return 0;
4388         if (stat(path, &sbuf) == 0) {
4389                 return 1;
4390         } else {
4391                 char *dot = strrchr(path, '.');
4392                 if (dot != NULL) {
4393                         *dot = '\0';
4394                         if (stat(path, &sbuf) == 0) {
4395                                 return 1;
4396                         }
4397                 }
4398         }
4399         return 0;
4400 }
4401 #endif
4402
4403 int
4404 x11_connect_display(void)
4405 {
4406         u_int display_number;
4407         const char *display;
4408         char buf[1024], *cp;
4409         struct addrinfo hints, *ai, *aitop;
4410         char strport[NI_MAXSERV];
4411         int gaierr, sock = 0;
4412
4413         /* Try to open a socket for the local X server. */
4414         display = getenv("DISPLAY");
4415         if (!display) {
4416                 error("DISPLAY not set.");
4417                 return -1;
4418         }
4419         /*
4420          * Now we decode the value of the DISPLAY variable and make a
4421          * connection to the real X server.
4422          */
4423
4424 #ifdef __APPLE__
4425         /* Check if display is a path to a socket (as set by launchd). */
4426         {
4427                 char path[PATH_MAX];
4428
4429                 if (is_path_to_xsocket(display, path, sizeof(path))) {
4430                         debug("x11_connect_display: $DISPLAY is launchd");
4431
4432                         /* Create a socket. */
4433                         sock = connect_local_xsocket_path(path);
4434                         if (sock < 0)
4435                                 return -1;
4436
4437                         /* OK, we now have a connection to the display. */
4438                         return sock;
4439                 }
4440         }
4441 #endif
4442         /*
4443          * Check if it is a unix domain socket.  Unix domain displays are in
4444          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
4445          */
4446         if (strncmp(display, "unix:", 5) == 0 ||
4447             display[0] == ':') {
4448                 /* Connect to the unix domain socket. */
4449                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
4450                         error("Could not parse display number from DISPLAY: %.100s",
4451                             display);
4452                         return -1;
4453                 }
4454                 /* Create a socket. */
4455                 sock = connect_local_xsocket(display_number);
4456                 if (sock < 0)
4457                         return -1;
4458
4459                 /* OK, we now have a connection to the display. */
4460                 return sock;
4461         }
4462         /*
4463          * Connect to an inet socket.  The DISPLAY value is supposedly
4464          * hostname:d[.s], where hostname may also be numeric IP address.
4465          */
4466         strlcpy(buf, display, sizeof(buf));
4467         cp = strchr(buf, ':');
4468         if (!cp) {
4469                 error("Could not find ':' in DISPLAY: %.100s", display);
4470                 return -1;
4471         }
4472         *cp = 0;
4473         /* buf now contains the host name.  But first we parse the display number. */
4474         if (sscanf(cp + 1, "%u", &display_number) != 1) {
4475                 error("Could not parse display number from DISPLAY: %.100s",
4476                     display);
4477                 return -1;
4478         }
4479
4480         /* Look up the host address */
4481         memset(&hints, 0, sizeof(hints));
4482         hints.ai_family = IPv4or6;
4483         hints.ai_socktype = SOCK_STREAM;
4484         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
4485         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
4486                 error("%.100s: unknown host. (%s)", buf,
4487                 ssh_gai_strerror(gaierr));
4488                 return -1;
4489         }
4490         for (ai = aitop; ai; ai = ai->ai_next) {
4491                 /* Create a socket. */
4492                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
4493                 if (sock < 0) {
4494                         debug2("socket: %.100s", strerror(errno));
4495                         continue;
4496                 }
4497                 /* Connect it to the display. */
4498                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
4499                         debug2("connect %.100s port %u: %.100s", buf,
4500                             6000 + display_number, strerror(errno));
4501                         close(sock);
4502                         continue;
4503                 }
4504                 /* Success */
4505                 break;
4506         }
4507         freeaddrinfo(aitop);
4508         if (!ai) {
4509                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
4510                     strerror(errno));
4511                 return -1;
4512         }
4513         set_nodelay(sock);
4514         return sock;
4515 }
4516
4517 /*
4518  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
4519  * the remote channel number.  We should do whatever we want, and respond
4520  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
4521  */
4522
4523 /* ARGSUSED */
4524 int
4525 x11_input_open(int type, u_int32_t seq, void *ctxt)
4526 {
4527         Channel *c = NULL;
4528         int remote_id, sock = 0;
4529         char *remote_host;
4530
4531         debug("Received X11 open request.");
4532
4533         remote_id = packet_get_int();
4534
4535         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
4536                 remote_host = packet_get_string(NULL);
4537         } else {
4538                 remote_host = xstrdup("unknown (remote did not supply name)");
4539         }
4540         packet_check_eom();
4541
4542         /* Obtain a connection to the real X display. */
4543         sock = x11_connect_display();
4544         if (sock != -1) {
4545                 /* Allocate a channel for this connection. */
4546                 c = channel_new("connected x11 socket",
4547                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
4548                     remote_host, 1);
4549                 c->remote_id = remote_id;
4550                 c->force_drain = 1;
4551         }
4552         free(remote_host);
4553         if (c == NULL) {
4554                 /* Send refusal to the remote host. */
4555                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4556                 packet_put_int(remote_id);
4557         } else {
4558                 /* Send a confirmation to the remote host. */
4559                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
4560                 packet_put_int(remote_id);
4561                 packet_put_int(c->self);
4562         }
4563         packet_send();
4564         return 0;
4565 }
4566
4567 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
4568 /* ARGSUSED */
4569 int
4570 deny_input_open(int type, u_int32_t seq, void *ctxt)
4571 {
4572         int rchan = packet_get_int();
4573
4574         switch (type) {
4575         case SSH_SMSG_AGENT_OPEN:
4576                 error("Warning: ssh server tried agent forwarding.");
4577                 break;
4578         case SSH_SMSG_X11_OPEN:
4579                 error("Warning: ssh server tried X11 forwarding.");
4580                 break;
4581         default:
4582                 error("deny_input_open: type %d", type);
4583                 break;
4584         }
4585         error("Warning: this is probably a break-in attempt by a malicious server.");
4586         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4587         packet_put_int(rchan);
4588         packet_send();
4589         return 0;
4590 }
4591
4592 /*
4593  * Requests forwarding of X11 connections, generates fake authentication
4594  * data, and enables authentication spoofing.
4595  * This should be called in the client only.
4596  */
4597 void
4598 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
4599     const char *proto, const char *data, int want_reply)
4600 {
4601         u_int data_len = (u_int) strlen(data) / 2;
4602         u_int i, value;
4603         char *new_data;
4604         int screen_number;
4605         const char *cp;
4606
4607         if (x11_saved_display == NULL)
4608                 x11_saved_display = xstrdup(disp);
4609         else if (strcmp(disp, x11_saved_display) != 0) {
4610                 error("x11_request_forwarding_with_spoofing: different "
4611                     "$DISPLAY already forwarded");
4612                 return;
4613         }
4614
4615         cp = strchr(disp, ':');
4616         if (cp)
4617                 cp = strchr(cp, '.');
4618         if (cp)
4619                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
4620         else
4621                 screen_number = 0;
4622
4623         if (x11_saved_proto == NULL) {
4624                 /* Save protocol name. */
4625                 x11_saved_proto = xstrdup(proto);
4626
4627                 /* Extract real authentication data. */
4628                 x11_saved_data = xmalloc(data_len);
4629                 for (i = 0; i < data_len; i++) {
4630                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
4631                                 fatal("x11_request_forwarding: bad "
4632                                     "authentication data: %.100s", data);
4633                         x11_saved_data[i] = value;
4634                 }
4635                 x11_saved_data_len = data_len;
4636
4637                 /* Generate fake data of the same length. */
4638                 x11_fake_data = xmalloc(data_len);
4639                 arc4random_buf(x11_fake_data, data_len);
4640                 x11_fake_data_len = data_len;
4641         }
4642
4643         /* Convert the fake data into hex. */
4644         new_data = tohex(x11_fake_data, data_len);
4645
4646         /* Send the request packet. */
4647         if (compat20) {
4648                 channel_request_start(client_session_id, "x11-req", want_reply);
4649                 packet_put_char(0);     /* XXX bool single connection */
4650         } else {
4651                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
4652         }
4653         packet_put_cstring(proto);
4654         packet_put_cstring(new_data);
4655         packet_put_int(screen_number);
4656         packet_send();
4657         packet_write_wait();
4658         free(new_data);
4659 }
4660
4661
4662 /* -- agent forwarding */
4663
4664 /* Sends a message to the server to request authentication fd forwarding. */
4665
4666 void
4667 auth_request_forwarding(void)
4668 {
4669         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
4670         packet_send();
4671         packet_write_wait();
4672 }