crypto/openssh/clientloop.c

   1 /* $OpenBSD: clientloop.c,v 1.311 2018/02/11 21:16:56 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  * The main loop for the interactive session (client side).
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  *
  15  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  *
  38  * SSH2 support added by Markus Friedl.
  39  * Copyright (c) 1999, 2000, 2001 Markus Friedl.  All rights reserved.
  40  *
  41  * Redistribution and use in source and binary forms, with or without
  42  * modification, are permitted provided that the following conditions
  43  * are met:
  44  * 1. Redistributions of source code must retain the above copyright
  45  *    notice, this list of conditions and the following disclaimer.
  46  * 2. Redistributions in binary form must reproduce the above copyright
  47  *    notice, this list of conditions and the following disclaimer in the
  48  *    documentation and/or other materials provided with the distribution.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  51  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  52  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  53  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  54  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  55  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  56  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  57  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  58  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  59  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  60  */
  61
  62 #include "includes.h"
  63
  64 #include <sys/types.h>
  65 #include <sys/ioctl.h>
  66 #ifdef HAVE_SYS_STAT_H
  67 # include <sys/stat.h>
  68 #endif
  69 #ifdef HAVE_SYS_TIME_H
  70 # include <sys/time.h>
  71 #endif
  72 #include <sys/socket.h>
  73
  74 #include <ctype.h>
  75 #include <errno.h>
  76 #ifdef HAVE_PATHS_H
  77 #include <paths.h>
  78 #endif
  79 #include <signal.h>
  80 #include <stdarg.h>
  81 #include <stdio.h>
  82 #include <stdlib.h>
  83 #include <string.h>
  84 #include <termios.h>
  85 #include <pwd.h>
  86 #include <unistd.h>
  87 #include <limits.h>
  88
  89 #include "openbsd-compat/sys-queue.h"
  90 #include "xmalloc.h"
  91 #include "ssh.h"
  92 #include "ssh2.h"
  93 #include "packet.h"
  94 #include "buffer.h"
  95 #include "compat.h"
  96 #include "channels.h"
  97 #include "dispatch.h"
  98 #include "key.h"
  99 #include "cipher.h"
 100 #include "kex.h"
 101 #include "myproposal.h"
 102 #include "log.h"
 103 #include "misc.h"
 104 #include "readconf.h"
 105 #include "clientloop.h"
 106 #include "sshconnect.h"
 107 #include "authfd.h"
 108 #include "atomicio.h"
 109 #include "sshpty.h"
 110 #include "match.h"
 111 #include "msg.h"
 112 #include "ssherr.h"
 113 #include "hostfile.h"
 114
 115 /* import options */
 116 extern Options options;
 117
 118 /* Flag indicating that stdin should be redirected from /dev/null. */
 119 extern int stdin_null_flag;
 120
 121 /* Flag indicating that no shell has been requested */
 122 extern int no_shell_flag;
 123
 124 /* Flag indicating that ssh should daemonise after authentication is complete */
 125 extern int fork_after_authentication_flag;
 126
 127 /* Control socket */
 128 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
 129
 130 /*
 131  * Name of the host we are connecting to.  This is the name given on the
 132  * command line, or the HostName specified for the user-supplied name in a
 133  * configuration file.
 134  */
 135 extern char *host;
 136
 137 /*
 138  * Flag to indicate that we have received a window change signal which has
 139  * not yet been processed.  This will cause a message indicating the new
 140  * window size to be sent to the server a little later.  This is volatile
 141  * because this is updated in a signal handler.
 142  */
 143 static volatile sig_atomic_t received_window_change_signal = 0;
 144 static volatile sig_atomic_t received_signal = 0;
 145
 146 /* Flag indicating whether the user's terminal is in non-blocking mode. */
 147 static int in_non_blocking_mode = 0;
 148
 149 /* Time when backgrounded control master using ControlPersist should exit */
 150 static time_t control_persist_exit_time = 0;
 151
 152 /* Common data for the client loop code. */
 153 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
 154 static int last_was_cr;         /* Last character was a newline. */
 155 static int exit_status;         /* Used to store the command exit status. */
 156 static Buffer stderr_buffer;    /* Used for final exit message. */
 157 static int connection_in;       /* Connection to server (input). */
 158 static int connection_out;      /* Connection to server (output). */
 159 static int need_rekeying;       /* Set to non-zero if rekeying is requested. */
 160 static int session_closed;      /* In SSH2: login session closed. */
 161 static u_int x11_refuse_time;   /* If >0, refuse x11 opens after this time. */
 162
 163 static void client_init_dispatch(void);
 164 int     session_ident = -1;
 165
 166 /* Track escape per proto2 channel */
 167 struct escape_filter_ctx {
 168         int escape_pending;
 169         int escape_char;
 170 };
 171
 172 /* Context for channel confirmation replies */
 173 struct channel_reply_ctx {
 174         const char *request_type;
 175         int id;
 176         enum confirm_action action;
 177 };
 178
 179 /* Global request success/failure callbacks */
 180 /* XXX move to struct ssh? */
 181 struct global_confirm {
 182         TAILQ_ENTRY(global_confirm) entry;
 183         global_confirm_cb *cb;
 184         void *ctx;
 185         int ref_count;
 186 };
 187 TAILQ_HEAD(global_confirms, global_confirm);
 188 static struct global_confirms global_confirms =
 189     TAILQ_HEAD_INITIALIZER(global_confirms);
 190
 191 void ssh_process_session2_setup(int, int, int, Buffer *);
 192
 193 /* Restores stdin to blocking mode. */
 194
 195 static void
 196 leave_non_blocking(void)
 197 {
 198         if (in_non_blocking_mode) {
 199                 unset_nonblock(fileno(stdin));
 200                 in_non_blocking_mode = 0;
 201         }
 202 }
 203
 204 /*
 205  * Signal handler for the window change signal (SIGWINCH).  This just sets a
 206  * flag indicating that the window has changed.
 207  */
 208 /*ARGSUSED */
 209 static void
 210 window_change_handler(int sig)
 211 {
 212         received_window_change_signal = 1;
 213 }
 214
 215 /*
 216  * Signal handler for signals that cause the program to terminate.  These
 217  * signals must be trapped to restore terminal modes.
 218  */
 219 /*ARGSUSED */
 220 static void
 221 signal_handler(int sig)
 222 {
 223         received_signal = sig;
 224         quit_pending = 1;
 225 }
 226
 227 /*
 228  * Sets control_persist_exit_time to the absolute time when the
 229  * backgrounded control master should exit due to expiry of the
 230  * ControlPersist timeout.  Sets it to 0 if we are not a backgrounded
 231  * control master process, or if there is no ControlPersist timeout.
 232  */
 233 static void
 234 set_control_persist_exit_time(struct ssh *ssh)
 235 {
 236         if (muxserver_sock == -1 || !options.control_persist
 237             || options.control_persist_timeout == 0) {
 238                 /* not using a ControlPersist timeout */
 239                 control_persist_exit_time = 0;
 240         } else if (channel_still_open(ssh)) {
 241                 /* some client connections are still open */
 242                 if (control_persist_exit_time > 0)
 243                         debug2("%s: cancel scheduled exit", __func__);
 244                 control_persist_exit_time = 0;
 245         } else if (control_persist_exit_time <= 0) {
 246                 /* a client connection has recently closed */
 247                 control_persist_exit_time = monotime() +
 248                         (time_t)options.control_persist_timeout;
 249                 debug2("%s: schedule exit in %d seconds", __func__,
 250                     options.control_persist_timeout);
 251         }
 252         /* else we are already counting down to the timeout */
 253 }
 254
 255 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
 256 static int
 257 client_x11_display_valid(const char *display)
 258 {
 259         size_t i, dlen;
 260
 261         if (display == NULL)
 262                 return 0;
 263
 264         dlen = strlen(display);
 265         for (i = 0; i < dlen; i++) {
 266                 if (!isalnum((u_char)display[i]) &&
 267                     strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
 268                         debug("Invalid character '%c' in DISPLAY", display[i]);
 269                         return 0;
 270                 }
 271         }
 272         return 1;
 273 }
 274
 275 #define SSH_X11_PROTO           "MIT-MAGIC-COOKIE-1"
 276 #define X11_TIMEOUT_SLACK       60
 277 int
 278 client_x11_get_proto(struct ssh *ssh, const char *display,
 279     const char *xauth_path, u_int trusted, u_int timeout,
 280     char **_proto, char **_data)
 281 {
 282         char cmd[1024], line[512], xdisplay[512];
 283         char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
 284         static char proto[512], data[512];
 285         FILE *f;
 286         int got_data = 0, generated = 0, do_unlink = 0, r;
 287         struct stat st;
 288         u_int now, x11_timeout_real;
 289
 290         *_proto = proto;
 291         *_data = data;
 292         proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
 293
 294         if (!client_x11_display_valid(display)) {
 295                 if (display != NULL)
 296                         logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
 297                             display);
 298                 return -1;
 299         }
 300         if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
 301                 debug("No xauth program.");
 302                 xauth_path = NULL;
 303         }
 304
 305         if (xauth_path != NULL) {
 306                 /*
 307                  * Handle FamilyLocal case where $DISPLAY does
 308                  * not match an authorization entry.  For this we
 309                  * just try "xauth list unix:displaynum.screennum".
 310                  * XXX: "localhost" match to determine FamilyLocal
 311                  *      is not perfect.
 312                  */
 313                 if (strncmp(display, "localhost:", 10) == 0) {
 314                         if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 315                             display + 10)) < 0 ||
 316                             (size_t)r >= sizeof(xdisplay)) {
 317                                 error("%s: display name too long", __func__);
 318                                 return -1;
 319                         }
 320                         display = xdisplay;
 321                 }
 322                 if (trusted == 0) {
 323                         /*
 324                          * Generate an untrusted X11 auth cookie.
 325                          *
 326                          * The authentication cookie should briefly outlive
 327                          * ssh's willingness to forward X11 connections to
 328                          * avoid nasty fail-open behaviour in the X server.
 329                          */
 330                         mktemp_proto(xauthdir, sizeof(xauthdir));
 331                         if (mkdtemp(xauthdir) == NULL) {
 332                                 error("%s: mkdtemp: %s",
 333                                     __func__, strerror(errno));
 334                                 return -1;
 335                         }
 336                         do_unlink = 1;
 337                         if ((r = snprintf(xauthfile, sizeof(xauthfile),
 338                             "%s/xauthfile", xauthdir)) < 0 ||
 339                             (size_t)r >= sizeof(xauthfile)) {
 340                                 error("%s: xauthfile path too long", __func__);
 341                                 unlink(xauthfile);
 342                                 rmdir(xauthdir);
 343                                 return -1;
 344                         }
 345
 346                         if (timeout >= UINT_MAX - X11_TIMEOUT_SLACK)
 347                                 x11_timeout_real = UINT_MAX;
 348                         else
 349                                 x11_timeout_real = timeout + X11_TIMEOUT_SLACK;
 350                         if ((r = snprintf(cmd, sizeof(cmd),
 351                             "%s -f %s generate %s " SSH_X11_PROTO
 352                             " untrusted timeout %u 2>" _PATH_DEVNULL,
 353                             xauth_path, xauthfile, display,
 354                             x11_timeout_real)) < 0 ||
 355                             (size_t)r >= sizeof(cmd))
 356                                 fatal("%s: cmd too long", __func__);
 357                         debug2("%s: %s", __func__, cmd);
 358                         if (x11_refuse_time == 0) {
 359                                 now = monotime() + 1;
 360                                 if (UINT_MAX - timeout < now)
 361                                         x11_refuse_time = UINT_MAX;
 362                                 else
 363                                         x11_refuse_time = now + timeout;
 364                                 channel_set_x11_refuse_time(ssh,
 365                                     x11_refuse_time);
 366                         }
 367                         if (system(cmd) == 0)
 368                                 generated = 1;
 369                 }
 370
 371                 /*
 372                  * When in untrusted mode, we read the cookie only if it was
 373                  * successfully generated as an untrusted one in the step
 374                  * above.
 375                  */
 376                 if (trusted || generated) {
 377                         snprintf(cmd, sizeof(cmd),
 378                             "%s %s%s list %s 2>" _PATH_DEVNULL,
 379                             xauth_path,
 380                             generated ? "-f " : "" ,
 381                             generated ? xauthfile : "",
 382                             display);
 383                         debug2("x11_get_proto: %s", cmd);
 384                         f = popen(cmd, "r");
 385                         if (f && fgets(line, sizeof(line), f) &&
 386                             sscanf(line, "%*s %511s %511s", proto, data) == 2)
 387                                 got_data = 1;
 388                         if (f)
 389                                 pclose(f);
 390                 }
 391         }
 392
 393         if (do_unlink) {
 394                 unlink(xauthfile);
 395                 rmdir(xauthdir);
 396         }
 397
 398         /* Don't fall back to fake X11 data for untrusted forwarding */
 399         if (!trusted && !got_data) {
 400                 error("Warning: untrusted X11 forwarding setup failed: "
 401                     "xauth key data not generated");
 402                 return -1;
 403         }
 404
 405         /*
 406          * If we didn't get authentication data, just make up some
 407          * data.  The forwarding code will check the validity of the
 408          * response anyway, and substitute this data.  The X11
 409          * server, however, will ignore this fake data and use
 410          * whatever authentication mechanisms it was using otherwise
 411          * for the local connection.
 412          */
 413         if (!got_data) {
 414                 u_int8_t rnd[16];
 415                 u_int i;
 416
 417                 logit("Warning: No xauth data; "
 418                     "using fake authentication data for X11 forwarding.");
 419                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 420                 arc4random_buf(rnd, sizeof(rnd));
 421                 for (i = 0; i < sizeof(rnd); i++) {
 422                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 423                             rnd[i]);
 424                 }
 425         }
 426
 427         return 0;
 428 }
 429
 430 /*
 431  * Checks if the client window has changed, and sends a packet about it to
 432  * the server if so.  The actual change is detected elsewhere (by a software
 433  * interrupt on Unix); this just checks the flag and sends a message if
 434  * appropriate.
 435  */
 436
 437 static void
 438 client_check_window_change(struct ssh *ssh)
 439 {
 440         if (!received_window_change_signal)
 441                 return;
 442         /** XXX race */
 443         received_window_change_signal = 0;
 444
 445         debug2("%s: changed", __func__);
 446
 447         channel_send_window_changes(ssh);
 448 }
 449
 450 static int
 451 client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
 452 {
 453         struct global_confirm *gc;
 454
 455         if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
 456                 return 0;
 457         if (gc->cb != NULL)
 458                 gc->cb(ssh, type, seq, gc->ctx);
 459         if (--gc->ref_count <= 0) {
 460                 TAILQ_REMOVE(&global_confirms, gc, entry);
 461                 explicit_bzero(gc, sizeof(*gc));
 462                 free(gc);
 463         }
 464
 465         packet_set_alive_timeouts(0);
 466         return 0;
 467 }
 468
 469 static void
 470 server_alive_check(void)
 471 {
 472         if (packet_inc_alive_timeouts() > options.server_alive_count_max) {
 473                 logit("Timeout, server %s not responding.", host);
 474                 cleanup_exit(255);
 475         }
 476         packet_start(SSH2_MSG_GLOBAL_REQUEST);
 477         packet_put_cstring("keepalive@openssh.com");
 478         packet_put_char(1);     /* boolean: want reply */
 479         packet_send();
 480         /* Insert an empty placeholder to maintain ordering */
 481         client_register_global_confirm(NULL, NULL);
 482 }
 483
 484 /*
 485  * Waits until the client can do something (some data becomes available on
 486  * one of the file descriptors).
 487  */
 488 static void
 489 client_wait_until_can_do_something(struct ssh *ssh,
 490     fd_set **readsetp, fd_set **writesetp,
 491     int *maxfdp, u_int *nallocp, int rekeying)
 492 {
 493         struct timeval tv, *tvp;
 494         int timeout_secs;
 495         time_t minwait_secs = 0, server_alive_time = 0, now = monotime();
 496         int ret;
 497
 498         /* Add any selections by the channel mechanism. */
 499         channel_prepare_select(active_state, readsetp, writesetp, maxfdp,
 500             nallocp, &minwait_secs);
 501
 502         /* channel_prepare_select could have closed the last channel */
 503         if (session_closed && !channel_still_open(ssh) &&
 504             !packet_have_data_to_write()) {
 505                 /* clear mask since we did not call select() */
 506                 memset(*readsetp, 0, *nallocp);
 507                 memset(*writesetp, 0, *nallocp);
 508                 return;
 509         }
 510
 511         FD_SET(connection_in, *readsetp);
 512
 513         /* Select server connection if have data to write to the server. */
 514         if (packet_have_data_to_write())
 515                 FD_SET(connection_out, *writesetp);
 516
 517         /*
 518          * Wait for something to happen.  This will suspend the process until
 519          * some selected descriptor can be read, written, or has some other
 520          * event pending, or a timeout expires.
 521          */
 522
 523         timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */
 524         if (options.server_alive_interval > 0) {
 525                 timeout_secs = options.server_alive_interval;
 526                 server_alive_time = now + options.server_alive_interval;
 527         }
 528         if (options.rekey_interval > 0 && !rekeying)
 529                 timeout_secs = MINIMUM(timeout_secs, packet_get_rekey_timeout());
 530         set_control_persist_exit_time(ssh);
 531         if (control_persist_exit_time > 0) {
 532                 timeout_secs = MINIMUM(timeout_secs,
 533                         control_persist_exit_time - now);
 534                 if (timeout_secs < 0)
 535                         timeout_secs = 0;
 536         }
 537         if (minwait_secs != 0)
 538                 timeout_secs = MINIMUM(timeout_secs, (int)minwait_secs);
 539         if (timeout_secs == INT_MAX)
 540                 tvp = NULL;
 541         else {
 542                 tv.tv_sec = timeout_secs;
 543                 tv.tv_usec = 0;
 544                 tvp = &tv;
 545         }
 546
 547         ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
 548         if (ret < 0) {
 549                 char buf[100];
 550
 551                 /*
 552                  * We have to clear the select masks, because we return.
 553                  * We have to return, because the mainloop checks for the flags
 554                  * set by the signal handlers.
 555                  */
 556                 memset(*readsetp, 0, *nallocp);
 557                 memset(*writesetp, 0, *nallocp);
 558
 559                 if (errno == EINTR)
 560                         return;
 561                 /* Note: we might still have data in the buffers. */
 562                 snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
 563                 buffer_append(&stderr_buffer, buf, strlen(buf));
 564                 quit_pending = 1;
 565         } else if (ret == 0) {
 566                 /*
 567                  * Timeout.  Could have been either keepalive or rekeying.
 568                  * Keepalive we check here, rekeying is checked in clientloop.
 569                  */
 570                 if (server_alive_time != 0 && server_alive_time <= monotime())
 571                         server_alive_check();
 572         }
 573
 574 }
 575
 576 static void
 577 client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
 578 {
 579         /* Flush stdout and stderr buffers. */
 580         if (buffer_len(bout) > 0)
 581                 atomicio(vwrite, fileno(stdout), buffer_ptr(bout),
 582                     buffer_len(bout));
 583         if (buffer_len(berr) > 0)
 584                 atomicio(vwrite, fileno(stderr), buffer_ptr(berr),
 585                     buffer_len(berr));
 586
 587         leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 588
 589         sshbuf_reset(bin);
 590         sshbuf_reset(bout);
 591         sshbuf_reset(berr);
 592
 593         /* Send the suspend signal to the program itself. */
 594         kill(getpid(), SIGTSTP);
 595
 596         /* Reset window sizes in case they have changed */
 597         received_window_change_signal = 1;
 598
 599         enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 600 }
 601
 602 static void
 603 client_process_net_input(fd_set *readset)
 604 {
 605         int len;
 606         char buf[SSH_IOBUFSZ];
 607
 608         /*
 609          * Read input from the server, and add any such data to the buffer of
 610          * the packet subsystem.
 611          */
 612         if (FD_ISSET(connection_in, readset)) {
 613                 /* Read as much as possible. */
 614                 len = read(connection_in, buf, sizeof(buf));
 615                 if (len == 0) {
 616                         /*
 617                          * Received EOF.  The remote host has closed the
 618                          * connection.
 619                          */
 620                         snprintf(buf, sizeof buf,
 621                             "Connection to %.300s closed by remote host.\r\n",
 622                             host);
 623                         buffer_append(&stderr_buffer, buf, strlen(buf));
 624                         quit_pending = 1;
 625                         return;
 626                 }
 627                 /*
 628                  * There is a kernel bug on Solaris that causes select to
 629                  * sometimes wake up even though there is no data available.
 630                  */
 631                 if (len < 0 &&
 632                     (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
 633                         len = 0;
 634
 635                 if (len < 0) {
 636                         /*
 637                          * An error has encountered.  Perhaps there is a
 638                          * network problem.
 639                          */
 640                         snprintf(buf, sizeof buf,
 641                             "Read from remote host %.300s: %.100s\r\n",
 642                             host, strerror(errno));
 643                         buffer_append(&stderr_buffer, buf, strlen(buf));
 644                         quit_pending = 1;
 645                         return;
 646                 }
 647                 packet_process_incoming(buf, len);
 648         }
 649 }
 650
 651 static void
 652 client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
 653 {
 654         struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
 655         char errmsg[256];
 656         int tochan;
 657
 658         /*
 659          * If a TTY was explicitly requested, then a failure to allocate
 660          * one is fatal.
 661          */
 662         if (cr->action == CONFIRM_TTY &&
 663             (options.request_tty == REQUEST_TTY_FORCE ||
 664             options.request_tty == REQUEST_TTY_YES))
 665                 cr->action = CONFIRM_CLOSE;
 666
 667         /* XXX supress on mux _client_ quietmode */
 668         tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
 669             c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
 670
 671         if (type == SSH2_MSG_CHANNEL_SUCCESS) {
 672                 debug2("%s request accepted on channel %d",
 673                     cr->request_type, c->self);
 674         } else if (type == SSH2_MSG_CHANNEL_FAILURE) {
 675                 if (tochan) {
 676                         snprintf(errmsg, sizeof(errmsg),
 677                             "%s request failed\r\n", cr->request_type);
 678                 } else {
 679                         snprintf(errmsg, sizeof(errmsg),
 680                             "%s request failed on channel %d",
 681                             cr->request_type, c->self);
 682                 }
 683                 /* If error occurred on primary session channel, then exit */
 684                 if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
 685                         fatal("%s", errmsg);
 686                 /*
 687                  * If error occurred on mux client, append to
 688                  * their stderr.
 689                  */
 690                 if (tochan) {
 691                         buffer_append(c->extended, errmsg, strlen(errmsg));
 692                 } else
 693                         error("%s", errmsg);
 694                 if (cr->action == CONFIRM_TTY) {
 695                         /*
 696                          * If a TTY allocation error occurred, then arrange
 697                          * for the correct TTY to leave raw mode.
 698                          */
 699                         if (c->self == session_ident)
 700                                 leave_raw_mode(0);
 701                         else
 702                                 mux_tty_alloc_failed(ssh, c);
 703                 } else if (cr->action == CONFIRM_CLOSE) {
 704                         chan_read_failed(ssh, c);
 705                         chan_write_failed(ssh, c);
 706                 }
 707         }
 708         free(cr);
 709 }
 710
 711 static void
 712 client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx)
 713 {
 714         free(ctx);
 715 }
 716
 717 void
 718 client_expect_confirm(struct ssh *ssh, int id, const char *request,
 719     enum confirm_action action)
 720 {
 721         struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
 722
 723         cr->request_type = request;
 724         cr->action = action;
 725
 726         channel_register_status_confirm(ssh, id, client_status_confirm,
 727             client_abandon_status_confirm, cr);
 728 }
 729
 730 void
 731 client_register_global_confirm(global_confirm_cb *cb, void *ctx)
 732 {
 733         struct global_confirm *gc, *last_gc;
 734
 735         /* Coalesce identical callbacks */
 736         last_gc = TAILQ_LAST(&global_confirms, global_confirms);
 737         if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
 738                 if (++last_gc->ref_count >= INT_MAX)
 739                         fatal("%s: last_gc->ref_count = %d",
 740                             __func__, last_gc->ref_count);
 741                 return;
 742         }
 743
 744         gc = xcalloc(1, sizeof(*gc));
 745         gc->cb = cb;
 746         gc->ctx = ctx;
 747         gc->ref_count = 1;
 748         TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
 749 }
 750
 751 static void
 752 process_cmdline(struct ssh *ssh)
 753 {
 754         void (*handler)(int);
 755         char *s, *cmd;
 756         int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
 757         struct Forward fwd;
 758
 759         memset(&fwd, 0, sizeof(fwd));
 760
 761         leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 762         handler = signal(SIGINT, SIG_IGN);
 763         cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
 764         if (s == NULL)
 765                 goto out;
 766         while (isspace((u_char)*s))
 767                 s++;
 768         if (*s == '-')
 769                 s++;    /* Skip cmdline '-', if any */
 770         if (*s == '\0')
 771                 goto out;
 772
 773         if (*s == 'h' || *s == 'H' || *s == '?') {
 774                 logit("Commands:");
 775                 logit("      -L[bind_address:]port:host:hostport    "
 776                     "Request local forward");
 777                 logit("      -R[bind_address:]port:host:hostport    "
 778                     "Request remote forward");
 779                 logit("      -D[bind_address:]port                  "
 780                     "Request dynamic forward");
 781                 logit("      -KL[bind_address:]port                 "
 782                     "Cancel local forward");
 783                 logit("      -KR[bind_address:]port                 "
 784                     "Cancel remote forward");
 785                 logit("      -KD[bind_address:]port                 "
 786                     "Cancel dynamic forward");
 787                 if (!options.permit_local_command)
 788                         goto out;
 789                 logit("      !args                                  "
 790                     "Execute local command");
 791                 goto out;
 792         }
 793
 794         if (*s == '!' && options.permit_local_command) {
 795                 s++;
 796                 ssh_local_cmd(s);
 797                 goto out;
 798         }
 799
 800         if (*s == 'K') {
 801                 delete = 1;
 802                 s++;
 803         }
 804         if (*s == 'L')
 805                 local = 1;
 806         else if (*s == 'R')
 807                 remote = 1;
 808         else if (*s == 'D')
 809                 dynamic = 1;
 810         else {
 811                 logit("Invalid command.");
 812                 goto out;
 813         }
 814
 815         while (isspace((u_char)*++s))
 816                 ;
 817
 818         /* XXX update list of forwards in options */
 819         if (delete) {
 820                 /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
 821                 if (!parse_forward(&fwd, s, 1, 0)) {
 822                         logit("Bad forwarding close specification.");
 823                         goto out;
 824                 }
 825                 if (remote)
 826                         ok = channel_request_rforward_cancel(ssh, &fwd) == 0;
 827                 else if (dynamic)
 828                         ok = channel_cancel_lport_listener(ssh, &fwd,
 829                             0, &options.fwd_opts) > 0;
 830                 else
 831                         ok = channel_cancel_lport_listener(ssh, &fwd,
 832                             CHANNEL_CANCEL_PORT_STATIC,
 833                             &options.fwd_opts) > 0;
 834                 if (!ok) {
 835                         logit("Unknown port forwarding.");
 836                         goto out;
 837                 }
 838                 logit("Canceled forwarding.");
 839         } else {
 840                 if (!parse_forward(&fwd, s, dynamic, remote)) {
 841                         logit("Bad forwarding specification.");
 842                         goto out;
 843                 }
 844                 if (local || dynamic) {
 845                         if (!channel_setup_local_fwd_listener(ssh, &fwd,
 846                             &options.fwd_opts)) {
 847                                 logit("Port forwarding failed.");
 848                                 goto out;
 849                         }
 850                 } else {
 851                         if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
 852                                 logit("Port forwarding failed.");
 853                                 goto out;
 854                         }
 855                 }
 856                 logit("Forwarding port.");
 857         }
 858
 859 out:
 860         signal(SIGINT, handler);
 861         enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 862         free(cmd);
 863         free(fwd.listen_host);
 864         free(fwd.listen_path);
 865         free(fwd.connect_host);
 866         free(fwd.connect_path);
 867 }
 868
 869 /* reasons to suppress output of an escape command in help output */
 870 #define SUPPRESS_NEVER          0       /* never suppress, always show */
 871 #define SUPPRESS_MUXCLIENT      1       /* don't show in mux client sessions */
 872 #define SUPPRESS_MUXMASTER      2       /* don't show in mux master sessions */
 873 #define SUPPRESS_SYSLOG         4       /* don't show when logging to syslog */
 874 struct escape_help_text {
 875         const char *cmd;
 876         const char *text;
 877         unsigned int flags;
 878 };
 879 static struct escape_help_text esc_txt[] = {
 880     {".",  "terminate session", SUPPRESS_MUXMASTER},
 881     {".",  "terminate connection (and any multiplexed sessions)",
 882         SUPPRESS_MUXCLIENT},
 883     {"B",  "send a BREAK to the remote system", SUPPRESS_NEVER},
 884     {"C",  "open a command line", SUPPRESS_MUXCLIENT},
 885     {"R",  "request rekey", SUPPRESS_NEVER},
 886     {"V/v",  "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
 887     {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
 888     {"#",  "list forwarded connections", SUPPRESS_NEVER},
 889     {"&",  "background ssh (when waiting for connections to terminate)",
 890         SUPPRESS_MUXCLIENT},
 891     {"?", "this message", SUPPRESS_NEVER},
 892 };
 893
 894 static void
 895 print_escape_help(Buffer *b, int escape_char, int mux_client, int using_stderr)
 896 {
 897         unsigned int i, suppress_flags;
 898         char string[1024];
 899
 900         snprintf(string, sizeof string, "%c?\r\n"
 901             "Supported escape sequences:\r\n", escape_char);
 902         buffer_append(b, string, strlen(string));
 903
 904         suppress_flags =
 905             (mux_client ? SUPPRESS_MUXCLIENT : 0) |
 906             (mux_client ? 0 : SUPPRESS_MUXMASTER) |
 907             (using_stderr ? 0 : SUPPRESS_SYSLOG);
 908
 909         for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
 910                 if (esc_txt[i].flags & suppress_flags)
 911                         continue;
 912                 snprintf(string, sizeof string, " %c%-3s - %s\r\n",
 913                     escape_char, esc_txt[i].cmd, esc_txt[i].text);
 914                 buffer_append(b, string, strlen(string));
 915         }
 916
 917         snprintf(string, sizeof string,
 918             " %c%c   - send the escape character by typing it twice\r\n"
 919             "(Note that escapes are only recognized immediately after "
 920             "newline.)\r\n", escape_char, escape_char);
 921         buffer_append(b, string, strlen(string));
 922 }
 923
 924 /*
 925  * Process the characters one by one.
 926  */
 927 static int
 928 process_escapes(struct ssh *ssh, Channel *c,
 929     Buffer *bin, Buffer *bout, Buffer *berr,
 930     char *buf, int len)
 931 {
 932         char string[1024];
 933         pid_t pid;
 934         int bytes = 0;
 935         u_int i;
 936         u_char ch;
 937         char *s;
 938         struct escape_filter_ctx *efc = c->filter_ctx == NULL ?
 939             NULL : (struct escape_filter_ctx *)c->filter_ctx;
 940
 941         if (c->filter_ctx == NULL)
 942                 return 0;
 943
 944         if (len <= 0)
 945                 return (0);
 946
 947         for (i = 0; i < (u_int)len; i++) {
 948                 /* Get one character at a time. */
 949                 ch = buf[i];
 950
 951                 if (efc->escape_pending) {
 952                         /* We have previously seen an escape character. */
 953                         /* Clear the flag now. */
 954                         efc->escape_pending = 0;
 955
 956                         /* Process the escaped character. */
 957                         switch (ch) {
 958                         case '.':
 959                                 /* Terminate the connection. */
 960                                 snprintf(string, sizeof string, "%c.\r\n",
 961                                     efc->escape_char);
 962                                 buffer_append(berr, string, strlen(string));
 963
 964                                 if (c && c->ctl_chan != -1) {
 965                                         chan_read_failed(ssh, c);
 966                                         chan_write_failed(ssh, c);
 967                                         if (c->detach_user) {
 968                                                 c->detach_user(ssh,
 969                                                     c->self, NULL);
 970                                         }
 971                                         c->type = SSH_CHANNEL_ABANDONED;
 972                                         buffer_clear(c->input);
 973                                         chan_ibuf_empty(ssh, c);
 974                                         return 0;
 975                                 } else
 976                                         quit_pending = 1;
 977                                 return -1;
 978
 979                         case 'Z' - 64:
 980                                 /* XXX support this for mux clients */
 981                                 if (c && c->ctl_chan != -1) {
 982                                         char b[16];
 983  noescape:
 984                                         if (ch == 'Z' - 64)
 985                                                 snprintf(b, sizeof b, "^Z");
 986                                         else
 987                                                 snprintf(b, sizeof b, "%c", ch);
 988                                         snprintf(string, sizeof string,
 989                                             "%c%s escape not available to "
 990                                             "multiplexed sessions\r\n",
 991                                             efc->escape_char, b);
 992                                         buffer_append(berr, string,
 993                                             strlen(string));
 994                                         continue;
 995                                 }
 996                                 /* Suspend the program. Inform the user */
 997                                 snprintf(string, sizeof string,
 998                                     "%c^Z [suspend ssh]\r\n", efc->escape_char);
 999                                 buffer_append(berr, string, strlen(string));
1000
1001                                 /* Restore terminal modes and suspend. */
1002                                 client_suspend_self(bin, bout, berr);
1003
1004                                 /* We have been continued. */
1005                                 continue;
1006
1007                         case 'B':
1008                                 snprintf(string, sizeof string,
1009                                     "%cB\r\n", efc->escape_char);
1010                                 buffer_append(berr, string, strlen(string));
1011                                 channel_request_start(ssh, c->self, "break", 0);
1012                                 packet_put_int(1000);
1013                                 packet_send();
1014                                 continue;
1015
1016                         case 'R':
1017                                 if (datafellows & SSH_BUG_NOREKEY)
1018                                         logit("Server does not "
1019                                             "support re-keying");
1020                                 else
1021                                         need_rekeying = 1;
1022                                 continue;
1023
1024                         case 'V':
1025                                 /* FALLTHROUGH */
1026                         case 'v':
1027                                 if (c && c->ctl_chan != -1)
1028                                         goto noescape;
1029                                 if (!log_is_on_stderr()) {
1030                                         snprintf(string, sizeof string,
1031                                             "%c%c [Logging to syslog]\r\n",
1032                                              efc->escape_char, ch);
1033                                         buffer_append(berr, string,
1034                                             strlen(string));
1035                                         continue;
1036                                 }
1037                                 if (ch == 'V' && options.log_level >
1038                                     SYSLOG_LEVEL_QUIET)
1039                                         log_change_level(--options.log_level);
1040                                 if (ch == 'v' && options.log_level <
1041                                     SYSLOG_LEVEL_DEBUG3)
1042                                         log_change_level(++options.log_level);
1043                                 snprintf(string, sizeof string,
1044                                     "%c%c [LogLevel %s]\r\n",
1045                                     efc->escape_char, ch,
1046                                     log_level_name(options.log_level));
1047                                 buffer_append(berr, string, strlen(string));
1048                                 continue;
1049
1050                         case '&':
1051                                 if (c && c->ctl_chan != -1)
1052                                         goto noescape;
1053                                 /*
1054                                  * Detach the program (continue to serve
1055                                  * connections, but put in background and no
1056                                  * more new connections).
1057                                  */
1058                                 /* Restore tty modes. */
1059                                 leave_raw_mode(
1060                                     options.request_tty == REQUEST_TTY_FORCE);
1061
1062                                 /* Stop listening for new connections. */
1063                                 channel_stop_listening(ssh);
1064
1065                                 snprintf(string, sizeof string,
1066                                     "%c& [backgrounded]\n", efc->escape_char);
1067                                 buffer_append(berr, string, strlen(string));
1068
1069                                 /* Fork into background. */
1070                                 pid = fork();
1071                                 if (pid < 0) {
1072                                         error("fork: %.100s", strerror(errno));
1073                                         continue;
1074                                 }
1075                                 if (pid != 0) { /* This is the parent. */
1076                                         /* The parent just exits. */
1077                                         exit(0);
1078                                 }
1079                                 /* The child continues serving connections. */
1080                                 buffer_append(bin, "\004", 1);
1081                                 /* fake EOF on stdin */
1082                                 return -1;
1083                         case '?':
1084                                 print_escape_help(berr, efc->escape_char,
1085                                     (c && c->ctl_chan != -1),
1086                                     log_is_on_stderr());
1087                                 continue;
1088
1089                         case '#':
1090                                 snprintf(string, sizeof string, "%c#\r\n",
1091                                     efc->escape_char);
1092                                 buffer_append(berr, string, strlen(string));
1093                                 s = channel_open_message(ssh);
1094                                 buffer_append(berr, s, strlen(s));
1095                                 free(s);
1096                                 continue;
1097
1098                         case 'C':
1099                                 if (c && c->ctl_chan != -1)
1100                                         goto noescape;
1101                                 process_cmdline(ssh);
1102                                 continue;
1103
1104                         default:
1105                                 if (ch != efc->escape_char) {
1106                                         buffer_put_char(bin, efc->escape_char);
1107                                         bytes++;
1108                                 }
1109                                 /* Escaped characters fall through here */
1110                                 break;
1111                         }
1112                 } else {
1113                         /*
1114                          * The previous character was not an escape char.
1115                          * Check if this is an escape.
1116                          */
1117                         if (last_was_cr && ch == efc->escape_char) {
1118                                 /*
1119                                  * It is. Set the flag and continue to
1120                                  * next character.
1121                                  */
1122                                 efc->escape_pending = 1;
1123                                 continue;
1124                         }
1125                 }
1126
1127                 /*
1128                  * Normal character.  Record whether it was a newline,
1129                  * and append it to the buffer.
1130                  */
1131                 last_was_cr = (ch == '\r' || ch == '\n');
1132                 buffer_put_char(bin, ch);
1133                 bytes++;
1134         }
1135         return bytes;
1136 }
1137
1138 /*
1139  * Get packets from the connection input buffer, and process them as long as
1140  * there are packets available.
1141  *
1142  * Any unknown packets received during the actual
1143  * session cause the session to terminate.  This is
1144  * intended to make debugging easier since no
1145  * confirmations are sent.  Any compatible protocol
1146  * extensions must be negotiated during the
1147  * preparatory phase.
1148  */
1149
1150 static void
1151 client_process_buffered_input_packets(void)
1152 {
1153         ssh_dispatch_run_fatal(active_state, DISPATCH_NONBLOCK, &quit_pending);
1154 }
1155
1156 /* scan buf[] for '~' before sending data to the peer */
1157
1158 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */
1159 void *
1160 client_new_escape_filter_ctx(int escape_char)
1161 {
1162         struct escape_filter_ctx *ret;
1163
1164         ret = xcalloc(1, sizeof(*ret));
1165         ret->escape_pending = 0;
1166         ret->escape_char = escape_char;
1167         return (void *)ret;
1168 }
1169
1170 /* Free the escape filter context on channel free */
1171 void
1172 client_filter_cleanup(struct ssh *ssh, int cid, void *ctx)
1173 {
1174         free(ctx);
1175 }
1176
1177 int
1178 client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len)
1179 {
1180         if (c->extended_usage != CHAN_EXTENDED_WRITE)
1181                 return 0;
1182
1183         return process_escapes(ssh, c, c->input, c->output, c->extended,
1184             buf, len);
1185 }
1186
1187 static void
1188 client_channel_closed(struct ssh *ssh, int id, void *arg)
1189 {
1190         channel_cancel_cleanup(ssh, id);
1191         session_closed = 1;
1192         leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1193 }
1194
1195 /*
1196  * Implements the interactive session with the server.  This is called after
1197  * the user has been authenticated, and a command has been started on the
1198  * remote host.  If escape_char != SSH_ESCAPECHAR_NONE, it is the character
1199  * used as an escape character for terminating or suspending the session.
1200  */
1201 int
1202 client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
1203     int ssh2_chan_id)
1204 {
1205         fd_set *readset = NULL, *writeset = NULL;
1206         double start_time, total_time;
1207         int r, max_fd = 0, max_fd2 = 0, len;
1208         u_int64_t ibytes, obytes;
1209         u_int nalloc = 0;
1210         char buf[100];
1211
1212         debug("Entering interactive session.");
1213
1214         if (options.control_master &&
1215             !option_clear_or_none(options.control_path)) {
1216                 debug("pledge: id");
1217                 if (pledge("stdio rpath wpath cpath unix inet dns recvfd proc exec id tty",
1218                     NULL) == -1)
1219                         fatal("%s pledge(): %s", __func__, strerror(errno));
1220
1221         } else if (options.forward_x11 || options.permit_local_command) {
1222                 debug("pledge: exec");
1223                 if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
1224                     NULL) == -1)
1225                         fatal("%s pledge(): %s", __func__, strerror(errno));
1226
1227         } else if (options.update_hostkeys) {
1228                 debug("pledge: filesystem full");
1229                 if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
1230                     NULL) == -1)
1231                         fatal("%s pledge(): %s", __func__, strerror(errno));
1232
1233         } else if (!option_clear_or_none(options.proxy_command) ||
1234             fork_after_authentication_flag) {
1235                 debug("pledge: proc");
1236                 if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
1237                         fatal("%s pledge(): %s", __func__, strerror(errno));
1238
1239         } else {
1240                 debug("pledge: network");
1241                 if (pledge("stdio unix inet dns proc tty", NULL) == -1)
1242                         fatal("%s pledge(): %s", __func__, strerror(errno));
1243         }
1244
1245         start_time = monotime_double();
1246
1247         /* Initialize variables. */
1248         last_was_cr = 1;
1249         exit_status = -1;
1250         connection_in = packet_get_connection_in();
1251         connection_out = packet_get_connection_out();
1252         max_fd = MAXIMUM(connection_in, connection_out);
1253
1254         quit_pending = 0;
1255
1256         /* Initialize buffers. */
1257         buffer_init(&stderr_buffer);
1258
1259         client_init_dispatch();
1260
1261         /*
1262          * Set signal handlers, (e.g. to restore non-blocking mode)
1263          * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
1264          */
1265         if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
1266                 signal(SIGHUP, signal_handler);
1267         if (signal(SIGINT, SIG_IGN) != SIG_IGN)
1268                 signal(SIGINT, signal_handler);
1269         if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
1270                 signal(SIGQUIT, signal_handler);
1271         if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
1272                 signal(SIGTERM, signal_handler);
1273         signal(SIGWINCH, window_change_handler);
1274
1275         if (have_pty)
1276                 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1277
1278         session_ident = ssh2_chan_id;
1279         if (session_ident != -1) {
1280                 if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
1281                         channel_register_filter(ssh, session_ident,
1282                             client_simple_escape_filter, NULL,
1283                             client_filter_cleanup,
1284                             client_new_escape_filter_ctx(
1285                             escape_char_arg));
1286                 }
1287                 channel_register_cleanup(ssh, session_ident,
1288                     client_channel_closed, 0);
1289         }
1290
1291         /* Main loop of the client for the interactive session mode. */
1292         while (!quit_pending) {
1293
1294                 /* Process buffered packets sent by the server. */
1295                 client_process_buffered_input_packets();
1296
1297                 if (session_closed && !channel_still_open(ssh))
1298                         break;
1299
1300                 if (ssh_packet_is_rekeying(ssh)) {
1301                         debug("rekeying in progress");
1302                 } else if (need_rekeying) {
1303                         /* manual rekey request */
1304                         debug("need rekeying");
1305                         if ((r = kex_start_rekex(ssh)) != 0)
1306                                 fatal("%s: kex_start_rekex: %s", __func__,
1307                                     ssh_err(r));
1308                         need_rekeying = 0;
1309                 } else {
1310                         /*
1311                          * Make packets from buffered channel data, and
1312                          * enqueue them for sending to the server.
1313                          */
1314                         if (packet_not_very_much_data_to_write())
1315                                 channel_output_poll(ssh);
1316
1317                         /*
1318                          * Check if the window size has changed, and buffer a
1319                          * message about it to the server if so.
1320                          */
1321                         client_check_window_change(ssh);
1322
1323                         if (quit_pending)
1324                                 break;
1325                 }
1326                 /*
1327                  * Wait until we have something to do (something becomes
1328                  * available on one of the descriptors).
1329                  */
1330                 max_fd2 = max_fd;
1331                 client_wait_until_can_do_something(ssh, &readset, &writeset,
1332                     &max_fd2, &nalloc, ssh_packet_is_rekeying(ssh));
1333
1334                 if (quit_pending)
1335                         break;
1336
1337                 /* Do channel operations unless rekeying in progress. */
1338                 if (!ssh_packet_is_rekeying(ssh))
1339                         channel_after_select(ssh, readset, writeset);
1340
1341                 /* Buffer input from the connection.  */
1342                 client_process_net_input(readset);
1343
1344                 if (quit_pending)
1345                         break;
1346
1347                 /*
1348                  * Send as much buffered packet data as possible to the
1349                  * sender.
1350                  */
1351                 if (FD_ISSET(connection_out, writeset))
1352                         packet_write_poll();
1353
1354                 /*
1355                  * If we are a backgrounded control master, and the
1356                  * timeout has expired without any active client
1357                  * connections, then quit.
1358                  */
1359                 if (control_persist_exit_time > 0) {
1360                         if (monotime() >= control_persist_exit_time) {
1361                                 debug("ControlPersist timeout expired");
1362                                 break;
1363                         }
1364                 }
1365         }
1366         free(readset);
1367         free(writeset);
1368
1369         /* Terminate the session. */
1370
1371         /* Stop watching for window change. */
1372         signal(SIGWINCH, SIG_DFL);
1373
1374         packet_start(SSH2_MSG_DISCONNECT);
1375         packet_put_int(SSH2_DISCONNECT_BY_APPLICATION);
1376         packet_put_cstring("disconnected by user");
1377         packet_put_cstring(""); /* language tag */
1378         packet_send();
1379         packet_write_wait();
1380
1381         channel_free_all(ssh);
1382
1383         if (have_pty)
1384                 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1385
1386         /* restore blocking io */
1387         if (!isatty(fileno(stdin)))
1388                 unset_nonblock(fileno(stdin));
1389         if (!isatty(fileno(stdout)))
1390                 unset_nonblock(fileno(stdout));
1391         if (!isatty(fileno(stderr)))
1392                 unset_nonblock(fileno(stderr));
1393
1394         /*
1395          * If there was no shell or command requested, there will be no remote
1396          * exit status to be returned.  In that case, clear error code if the
1397          * connection was deliberately terminated at this end.
1398          */
1399         if (no_shell_flag && received_signal == SIGTERM) {
1400                 received_signal = 0;
1401                 exit_status = 0;
1402         }
1403
1404         if (received_signal) {
1405                 verbose("Killed by signal %d.", (int) received_signal);
1406                 cleanup_exit(0);
1407         }
1408
1409         /*
1410          * In interactive mode (with pseudo tty) display a message indicating
1411          * that the connection has been closed.
1412          */
1413         if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
1414                 snprintf(buf, sizeof buf,
1415                     "Connection to %.64s closed.\r\n", host);
1416                 buffer_append(&stderr_buffer, buf, strlen(buf));
1417         }
1418
1419         /* Output any buffered data for stderr. */
1420         if (buffer_len(&stderr_buffer) > 0) {
1421                 len = atomicio(vwrite, fileno(stderr),
1422                     buffer_ptr(&stderr_buffer), buffer_len(&stderr_buffer));
1423                 if (len < 0 || (u_int)len != buffer_len(&stderr_buffer))
1424                         error("Write failed flushing stderr buffer.");
1425                 else
1426                         buffer_consume(&stderr_buffer, len);
1427         }
1428
1429         /* Clear and free any buffers. */
1430         explicit_bzero(buf, sizeof(buf));
1431         buffer_free(&stderr_buffer);
1432
1433         /* Report bytes transferred, and transfer rates. */
1434         total_time = monotime_double() - start_time;
1435         packet_get_bytes(&ibytes, &obytes);
1436         verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
1437             (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
1438         if (total_time > 0)
1439                 verbose("Bytes per second: sent %.1f, received %.1f",
1440                     obytes / total_time, ibytes / total_time);
1441         /* Return the exit status of the program. */
1442         debug("Exit status %d", exit_status);
1443         return exit_status;
1444 }
1445
1446 /*********/
1447
1448 static Channel *
1449 client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
1450     int rchan, u_int rwindow, u_int rmaxpack)
1451 {
1452         Channel *c = NULL;
1453         struct sshbuf *b = NULL;
1454         char *listen_address, *originator_address;
1455         u_short listen_port, originator_port;
1456         int r;
1457
1458         /* Get rest of the packet */
1459         listen_address = packet_get_string(NULL);
1460         listen_port = packet_get_int();
1461         originator_address = packet_get_string(NULL);
1462         originator_port = packet_get_int();
1463         packet_check_eom();
1464
1465         debug("%s: listen %s port %d, originator %s port %d", __func__,
1466             listen_address, listen_port, originator_address, originator_port);
1467
1468         c = channel_connect_by_listen_address(ssh, listen_address, listen_port,
1469             "forwarded-tcpip", originator_address);
1470
1471         if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1472                 if ((b = sshbuf_new()) == NULL) {
1473                         error("%s: alloc reply", __func__);
1474                         goto out;
1475                 }
1476                 /* reconstruct and send to muxclient */
1477                 if ((r = sshbuf_put_u8(b, 0)) != 0 ||   /* padlen */
1478                     (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1479                     (r = sshbuf_put_cstring(b, request_type)) != 0 ||
1480                     (r = sshbuf_put_u32(b, rchan)) != 0 ||
1481                     (r = sshbuf_put_u32(b, rwindow)) != 0 ||
1482                     (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
1483                     (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
1484                     (r = sshbuf_put_u32(b, listen_port)) != 0 ||
1485                     (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
1486                     (r = sshbuf_put_u32(b, originator_port)) != 0 ||
1487                     (r = sshbuf_put_stringb(c->output, b)) != 0) {
1488                         error("%s: compose for muxclient %s", __func__,
1489                             ssh_err(r));
1490                         goto out;
1491                 }
1492         }
1493
1494  out:
1495         sshbuf_free(b);
1496         free(originator_address);
1497         free(listen_address);
1498         return c;
1499 }
1500
1501 static Channel *
1502 client_request_forwarded_streamlocal(struct ssh *ssh,
1503     const char *request_type, int rchan)
1504 {
1505         Channel *c = NULL;
1506         char *listen_path;
1507
1508         /* Get the remote path. */
1509         listen_path = packet_get_string(NULL);
1510         /* XXX: Skip reserved field for now. */
1511         if (packet_get_string_ptr(NULL) == NULL)
1512                 fatal("%s: packet_get_string_ptr failed", __func__);
1513         packet_check_eom();
1514
1515         debug("%s: %s", __func__, listen_path);
1516
1517         c = channel_connect_by_listen_path(ssh, listen_path,
1518             "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
1519         free(listen_path);
1520         return c;
1521 }
1522
1523 static Channel *
1524 client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
1525 {
1526         Channel *c = NULL;
1527         char *originator;
1528         u_short originator_port;
1529         int sock;
1530
1531         if (!options.forward_x11) {
1532                 error("Warning: ssh server tried X11 forwarding.");
1533                 error("Warning: this is probably a break-in attempt by a "
1534                     "malicious server.");
1535                 return NULL;
1536         }
1537         if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
1538                 verbose("Rejected X11 connection after ForwardX11Timeout "
1539                     "expired");
1540                 return NULL;
1541         }
1542         originator = packet_get_string(NULL);
1543         originator_port = packet_get_int();
1544         packet_check_eom();
1545         /* XXX check permission */
1546         debug("client_request_x11: request from %s %d", originator,
1547             originator_port);
1548         free(originator);
1549         sock = x11_connect_display(ssh);
1550         if (sock < 0)
1551                 return NULL;
1552         c = channel_new(ssh, "x11",
1553             SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1554             CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1555         c->force_drain = 1;
1556         return c;
1557 }
1558
1559 static Channel *
1560 client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
1561 {
1562         Channel *c = NULL;
1563         int r, sock;
1564
1565         if (!options.forward_agent) {
1566                 error("Warning: ssh server tried agent forwarding.");
1567                 error("Warning: this is probably a break-in attempt by a "
1568                     "malicious server.");
1569                 return NULL;
1570         }
1571         if ((r = ssh_get_authentication_socket(&sock)) != 0) {
1572                 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1573                         debug("%s: ssh_get_authentication_socket: %s",
1574                             __func__, ssh_err(r));
1575                 return NULL;
1576         }
1577         c = channel_new(ssh, "authentication agent connection",
1578             SSH_CHANNEL_OPEN, sock, sock, -1,
1579             CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
1580             "authentication agent connection", 1);
1581         c->force_drain = 1;
1582         return c;
1583 }
1584
1585 char *
1586 client_request_tun_fwd(struct ssh *ssh, int tun_mode,
1587     int local_tun, int remote_tun)
1588 {
1589         Channel *c;
1590         int fd;
1591         char *ifname = NULL;
1592
1593         if (tun_mode == SSH_TUNMODE_NO)
1594                 return 0;
1595
1596         debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
1597
1598         /* Open local tunnel device */
1599         if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
1600                 error("Tunnel device open failed.");
1601                 return NULL;
1602         }
1603         debug("Tunnel forwarding using interface %s", ifname);
1604
1605         c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1606             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1607         c->datagram = 1;
1608
1609 #if defined(SSH_TUN_FILTER)
1610         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1611                 channel_register_filter(ssh, c->self, sys_tun_infilter,
1612                     sys_tun_outfilter, NULL, NULL);
1613 #endif
1614
1615         packet_start(SSH2_MSG_CHANNEL_OPEN);
1616         packet_put_cstring("tun@openssh.com");
1617         packet_put_int(c->self);
1618         packet_put_int(c->local_window_max);
1619         packet_put_int(c->local_maxpacket);
1620         packet_put_int(tun_mode);
1621         packet_put_int(remote_tun);
1622         packet_send();
1623
1624         return ifname;
1625 }
1626
1627 /* XXXX move to generic input handler */
1628 static int
1629 client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
1630 {
1631         Channel *c = NULL;
1632         char *ctype;
1633         int rchan;
1634         u_int rmaxpack, rwindow, len;
1635
1636         ctype = packet_get_string(&len);
1637         rchan = packet_get_int();
1638         rwindow = packet_get_int();
1639         rmaxpack = packet_get_int();
1640
1641         debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1642             ctype, rchan, rwindow, rmaxpack);
1643
1644         if (strcmp(ctype, "forwarded-tcpip") == 0) {
1645                 c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
1646                     rmaxpack);
1647         } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
1648                 c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
1649         } else if (strcmp(ctype, "x11") == 0) {
1650                 c = client_request_x11(ssh, ctype, rchan);
1651         } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1652                 c = client_request_agent(ssh, ctype, rchan);
1653         }
1654         if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1655                 debug3("proxied to downstream: %s", ctype);
1656         } else if (c != NULL) {
1657                 debug("confirm %s", ctype);
1658                 c->remote_id = rchan;
1659                 c->have_remote_id = 1;
1660                 c->remote_window = rwindow;
1661                 c->remote_maxpacket = rmaxpack;
1662                 if (c->type != SSH_CHANNEL_CONNECTING) {
1663                         packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1664                         packet_put_int(c->remote_id);
1665                         packet_put_int(c->self);
1666                         packet_put_int(c->local_window);
1667                         packet_put_int(c->local_maxpacket);
1668                         packet_send();
1669                 }
1670         } else {
1671                 debug("failure %s", ctype);
1672                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1673                 packet_put_int(rchan);
1674                 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1675                 packet_put_cstring("open failed");
1676                 packet_put_cstring("");
1677                 packet_send();
1678         }
1679         free(ctype);
1680         return 0;
1681 }
1682
1683 static int
1684 client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
1685 {
1686         Channel *c = NULL;
1687         int exitval, id, reply, success = 0;
1688         char *rtype;
1689
1690         id = packet_get_int();
1691         c = channel_lookup(ssh, id);
1692         if (channel_proxy_upstream(c, type, seq, ssh))
1693                 return 0;
1694         rtype = packet_get_string(NULL);
1695         reply = packet_get_char();
1696
1697         debug("client_input_channel_req: channel %d rtype %s reply %d",
1698             id, rtype, reply);
1699
1700         if (id == -1) {
1701                 error("client_input_channel_req: request for channel -1");
1702         } else if (c == NULL) {
1703                 error("client_input_channel_req: channel %d: "
1704                     "unknown channel", id);
1705         } else if (strcmp(rtype, "eow@openssh.com") == 0) {
1706                 packet_check_eom();
1707                 chan_rcvd_eow(ssh, c);
1708         } else if (strcmp(rtype, "exit-status") == 0) {
1709                 exitval = packet_get_int();
1710                 if (c->ctl_chan != -1) {
1711                         mux_exit_message(ssh, c, exitval);
1712                         success = 1;
1713                 } else if (id == session_ident) {
1714                         /* Record exit value of local session */
1715                         success = 1;
1716                         exit_status = exitval;
1717                 } else {
1718                         /* Probably for a mux channel that has already closed */
1719                         debug("%s: no sink for exit-status on channel %d",
1720                             __func__, id);
1721                 }
1722                 packet_check_eom();
1723         }
1724         if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
1725                 if (!c->have_remote_id)
1726                         fatal("%s: channel %d: no remote_id",
1727                             __func__, c->self);
1728                 packet_start(success ?
1729                     SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1730                 packet_put_int(c->remote_id);
1731                 packet_send();
1732         }
1733         free(rtype);
1734         return 0;
1735 }
1736
1737 struct hostkeys_update_ctx {
1738         /* The hostname and (optionally) IP address string for the server */
1739         char *host_str, *ip_str;
1740
1741         /*
1742          * Keys received from the server and a flag for each indicating
1743          * whether they already exist in known_hosts.
1744          * keys_seen is filled in by hostkeys_find() and later (for new
1745          * keys) by client_global_hostkeys_private_confirm().
1746          */
1747         struct sshkey **keys;
1748         int *keys_seen;
1749         size_t nkeys, nnew;
1750
1751         /*
1752          * Keys that are in known_hosts, but were not present in the update
1753          * from the server (i.e. scheduled to be deleted).
1754          * Filled in by hostkeys_find().
1755          */
1756         struct sshkey **old_keys;
1757         size_t nold;
1758 };
1759
1760 static void
1761 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
1762 {
1763         size_t i;
1764
1765         if (ctx == NULL)
1766                 return;
1767         for (i = 0; i < ctx->nkeys; i++)
1768                 sshkey_free(ctx->keys[i]);
1769         free(ctx->keys);
1770         free(ctx->keys_seen);
1771         for (i = 0; i < ctx->nold; i++)
1772                 sshkey_free(ctx->old_keys[i]);
1773         free(ctx->old_keys);
1774         free(ctx->host_str);
1775         free(ctx->ip_str);
1776         free(ctx);
1777 }
1778
1779 static int
1780 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
1781 {
1782         struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
1783         size_t i;
1784         struct sshkey **tmp;
1785
1786         if (l->status != HKF_STATUS_MATCHED || l->key == NULL)
1787                 return 0;
1788
1789         /* Mark off keys we've already seen for this host */
1790         for (i = 0; i < ctx->nkeys; i++) {
1791                 if (sshkey_equal(l->key, ctx->keys[i])) {
1792                         debug3("%s: found %s key at %s:%ld", __func__,
1793                             sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
1794                         ctx->keys_seen[i] = 1;
1795                         return 0;
1796                 }
1797         }
1798         /* This line contained a key that not offered by the server */
1799         debug3("%s: deprecated %s key at %s:%ld", __func__,
1800             sshkey_ssh_name(l->key), l->path, l->linenum);
1801         if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
1802             sizeof(*ctx->old_keys))) == NULL)
1803                 fatal("%s: recallocarray failed nold = %zu",
1804                     __func__, ctx->nold);
1805         ctx->old_keys = tmp;
1806         ctx->old_keys[ctx->nold++] = l->key;
1807         l->key = NULL;
1808
1809         return 0;
1810 }
1811
1812 static void
1813 update_known_hosts(struct hostkeys_update_ctx *ctx)
1814 {
1815         int r, was_raw = 0;
1816         int loglevel = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK ?
1817             SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
1818         char *fp, *response;
1819         size_t i;
1820
1821         for (i = 0; i < ctx->nkeys; i++) {
1822                 if (ctx->keys_seen[i] != 2)
1823                         continue;
1824                 if ((fp = sshkey_fingerprint(ctx->keys[i],
1825                     options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
1826                         fatal("%s: sshkey_fingerprint failed", __func__);
1827                 do_log2(loglevel, "Learned new hostkey: %s %s",
1828                     sshkey_type(ctx->keys[i]), fp);
1829                 free(fp);
1830         }
1831         for (i = 0; i < ctx->nold; i++) {
1832                 if ((fp = sshkey_fingerprint(ctx->old_keys[i],
1833                     options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
1834                         fatal("%s: sshkey_fingerprint failed", __func__);
1835                 do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
1836                     sshkey_type(ctx->old_keys[i]), fp);
1837                 free(fp);
1838         }
1839         if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1840                 if (get_saved_tio() != NULL) {
1841                         leave_raw_mode(1);
1842                         was_raw = 1;
1843                 }
1844                 response = NULL;
1845                 for (i = 0; !quit_pending && i < 3; i++) {
1846                         free(response);
1847                         response = read_passphrase("Accept updated hostkeys? "
1848                             "(yes/no): ", RP_ECHO);
1849                         if (strcasecmp(response, "yes") == 0)
1850                                 break;
1851                         else if (quit_pending || response == NULL ||
1852                             strcasecmp(response, "no") == 0) {
1853                                 options.update_hostkeys = 0;
1854                                 break;
1855                         } else {
1856                                 do_log2(loglevel, "Please enter "
1857                                     "\"yes\" or \"no\"");
1858                         }
1859                 }
1860                 if (quit_pending || i >= 3 || response == NULL)
1861                         options.update_hostkeys = 0;
1862                 free(response);
1863                 if (was_raw)
1864                         enter_raw_mode(1);
1865         }
1866
1867         /*
1868          * Now that all the keys are verified, we can go ahead and replace
1869          * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
1870          * cancel the operation).
1871          */
1872         if (options.update_hostkeys != 0 &&
1873             (r = hostfile_replace_entries(options.user_hostfiles[0],
1874             ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,
1875             options.hash_known_hosts, 0,
1876             options.fingerprint_hash)) != 0)
1877                 error("%s: hostfile_replace_entries failed: %s",
1878                     __func__, ssh_err(r));
1879 }
1880
1881 static void
1882 client_global_hostkeys_private_confirm(struct ssh *ssh, int type,
1883     u_int32_t seq, void *_ctx)
1884 {
1885         struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
1886         size_t i, ndone;
1887         struct sshbuf *signdata;
1888         int r, kexsigtype, use_kexsigtype;
1889         const u_char *sig;
1890         size_t siglen;
1891
1892         if (ctx->nnew == 0)
1893                 fatal("%s: ctx->nnew == 0", __func__); /* sanity */
1894         if (type != SSH2_MSG_REQUEST_SUCCESS) {
1895                 error("Server failed to confirm ownership of "
1896                     "private host keys");
1897                 hostkeys_update_ctx_free(ctx);
1898                 return;
1899         }
1900         kexsigtype = sshkey_type_plain(
1901             sshkey_type_from_name(ssh->kex->hostkey_alg));
1902
1903         if ((signdata = sshbuf_new()) == NULL)
1904                 fatal("%s: sshbuf_new failed", __func__);
1905         /* Don't want to accidentally accept an unbound signature */
1906         if (ssh->kex->session_id_len == 0)
1907                 fatal("%s: ssh->kex->session_id_len == 0", __func__);
1908         /*
1909          * Expect a signature for each of the ctx->nnew private keys we
1910          * haven't seen before. They will be in the same order as the
1911          * ctx->keys where the corresponding ctx->keys_seen[i] == 0.
1912          */
1913         for (ndone = i = 0; i < ctx->nkeys; i++) {
1914                 if (ctx->keys_seen[i])
1915                         continue;
1916                 /* Prepare data to be signed: session ID, unique string, key */
1917                 sshbuf_reset(signdata);
1918                 if ( (r = sshbuf_put_cstring(signdata,
1919                     "hostkeys-prove-00@openssh.com")) != 0 ||
1920                     (r = sshbuf_put_string(signdata, ssh->kex->session_id,
1921                     ssh->kex->session_id_len)) != 0 ||
1922                     (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
1923                         fatal("%s: failed to prepare signature: %s",
1924                             __func__, ssh_err(r));
1925                 /* Extract and verify signature */
1926                 if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
1927                         error("%s: couldn't parse message: %s",
1928                             __func__, ssh_err(r));
1929                         goto out;
1930                 }
1931                 /*
1932                  * For RSA keys, prefer to use the signature type negotiated
1933                  * during KEX to the default (SHA1).
1934                  */
1935                 use_kexsigtype = kexsigtype == KEY_RSA &&
1936                     sshkey_type_plain(ctx->keys[i]->type) == KEY_RSA;
1937                 if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
1938                     sshbuf_ptr(signdata), sshbuf_len(signdata),
1939                     use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 0) {
1940                         error("%s: server gave bad signature for %s key %zu",
1941                             __func__, sshkey_type(ctx->keys[i]), i);
1942                         goto out;
1943                 }
1944                 /* Key is good. Mark it as 'seen' */
1945                 ctx->keys_seen[i] = 2;
1946                 ndone++;
1947         }
1948         if (ndone != ctx->nnew)
1949                 fatal("%s: ndone != ctx->nnew (%zu / %zu)", __func__,
1950                     ndone, ctx->nnew);  /* Shouldn't happen */
1951         ssh_packet_check_eom(ssh);
1952
1953         /* Make the edits to known_hosts */
1954         update_known_hosts(ctx);
1955  out:
1956         hostkeys_update_ctx_free(ctx);
1957 }
1958
1959 /*
1960  * Returns non-zero if the key is accepted by HostkeyAlgorithms.
1961  * Made slightly less trivial by the multiple RSA signature algorithm names.
1962  */
1963 static int
1964 key_accepted_by_hostkeyalgs(const struct sshkey *key)
1965 {
1966         const char *ktype = sshkey_ssh_name(key);
1967         const char *hostkeyalgs = options.hostkeyalgorithms != NULL ?
1968             options.hostkeyalgorithms : KEX_DEFAULT_PK_ALG;
1969
1970         if (key == NULL || key->type == KEY_UNSPEC)
1971                 return 0;
1972         if (key->type == KEY_RSA &&
1973             (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
1974             match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
1975                 return 1;
1976         return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
1977 }
1978
1979 /*
1980  * Handle hostkeys-00@openssh.com global request to inform the client of all
1981  * the server's hostkeys. The keys are checked against the user's
1982  * HostkeyAlgorithms preference before they are accepted.
1983  */
1984 static int
1985 client_input_hostkeys(void)
1986 {
1987         struct ssh *ssh = active_state; /* XXX */
1988         const u_char *blob = NULL;
1989         size_t i, len = 0;
1990         struct sshbuf *buf = NULL;
1991         struct sshkey *key = NULL, **tmp;
1992         int r;
1993         char *fp;
1994         static int hostkeys_seen = 0; /* XXX use struct ssh */
1995         extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
1996         struct hostkeys_update_ctx *ctx = NULL;
1997
1998         if (hostkeys_seen)
1999                 fatal("%s: server already sent hostkeys", __func__);
2000         if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
2001             options.batch_mode)
2002                 return 1; /* won't ask in batchmode, so don't even try */
2003         if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
2004                 return 1;
2005
2006         ctx = xcalloc(1, sizeof(*ctx));
2007         while (ssh_packet_remaining(ssh) > 0) {
2008                 sshkey_free(key);
2009                 key = NULL;
2010                 if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
2011                         error("%s: couldn't parse message: %s",
2012                             __func__, ssh_err(r));
2013                         goto out;
2014                 }
2015                 if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
2016                         error("%s: parse key: %s", __func__, ssh_err(r));
2017                         goto out;
2018                 }
2019                 fp = sshkey_fingerprint(key, options.fingerprint_hash,
2020                     SSH_FP_DEFAULT);
2021                 debug3("%s: received %s key %s", __func__,
2022                     sshkey_type(key), fp);
2023                 free(fp);
2024
2025                 if (!key_accepted_by_hostkeyalgs(key)) {
2026                         debug3("%s: %s key not permitted by HostkeyAlgorithms",
2027                             __func__, sshkey_ssh_name(key));
2028                         continue;
2029                 }
2030                 /* Skip certs */
2031                 if (sshkey_is_cert(key)) {
2032                         debug3("%s: %s key is a certificate; skipping",
2033                             __func__, sshkey_ssh_name(key));
2034                         continue;
2035                 }
2036                 /* Ensure keys are unique */
2037                 for (i = 0; i < ctx->nkeys; i++) {
2038                         if (sshkey_equal(key, ctx->keys[i])) {
2039                                 error("%s: received duplicated %s host key",
2040                                     __func__, sshkey_ssh_name(key));
2041                                 goto out;
2042                         }
2043                 }
2044                 /* Key is good, record it */
2045                 if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
2046                     sizeof(*ctx->keys))) == NULL)
2047                         fatal("%s: recallocarray failed nkeys = %zu",
2048                             __func__, ctx->nkeys);
2049                 ctx->keys = tmp;
2050                 ctx->keys[ctx->nkeys++] = key;
2051                 key = NULL;
2052         }
2053
2054         if (ctx->nkeys == 0) {
2055                 debug("%s: server sent no hostkeys", __func__);
2056                 goto out;
2057         }
2058
2059         if ((ctx->keys_seen = calloc(ctx->nkeys,
2060             sizeof(*ctx->keys_seen))) == NULL)
2061                 fatal("%s: calloc failed", __func__);
2062
2063         get_hostfile_hostname_ipaddr(host,
2064             options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
2065             options.port, &ctx->host_str,
2066             options.check_host_ip ? &ctx->ip_str : NULL);
2067
2068         /* Find which keys we already know about. */
2069         if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find,
2070             ctx, ctx->host_str, ctx->ip_str,
2071             HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
2072                 error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
2073                 goto out;
2074         }
2075
2076         /* Figure out if we have any new keys to add */
2077         ctx->nnew = 0;
2078         for (i = 0; i < ctx->nkeys; i++) {
2079                 if (!ctx->keys_seen[i])
2080                         ctx->nnew++;
2081         }
2082
2083         debug3("%s: %zu keys from server: %zu new, %zu retained. %zu to remove",
2084             __func__, ctx->nkeys, ctx->nnew, ctx->nkeys - ctx->nnew, ctx->nold);
2085
2086         if (ctx->nnew == 0 && ctx->nold != 0) {
2087                 /* We have some keys to remove. Just do it. */
2088                 update_known_hosts(ctx);
2089         } else if (ctx->nnew != 0) {
2090                 /*
2091                  * We have received hitherto-unseen keys from the server.
2092                  * Ask the server to confirm ownership of the private halves.
2093                  */
2094                 debug3("%s: asking server to prove ownership for %zu keys",
2095                     __func__, ctx->nnew);
2096                 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2097                     (r = sshpkt_put_cstring(ssh,
2098                     "hostkeys-prove-00@openssh.com")) != 0 ||
2099                     (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
2100                         fatal("%s: cannot prepare packet: %s",
2101                             __func__, ssh_err(r));
2102                 if ((buf = sshbuf_new()) == NULL)
2103                         fatal("%s: sshbuf_new", __func__);
2104                 for (i = 0; i < ctx->nkeys; i++) {
2105                         if (ctx->keys_seen[i])
2106                                 continue;
2107                         sshbuf_reset(buf);
2108                         if ((r = sshkey_putb(ctx->keys[i], buf)) != 0)
2109                                 fatal("%s: sshkey_putb: %s",
2110                                     __func__, ssh_err(r));
2111                         if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
2112                                 fatal("%s: sshpkt_put_string: %s",
2113                                     __func__, ssh_err(r));
2114                 }
2115                 if ((r = sshpkt_send(ssh)) != 0)
2116                         fatal("%s: sshpkt_send: %s", __func__, ssh_err(r));
2117                 client_register_global_confirm(
2118                     client_global_hostkeys_private_confirm, ctx);
2119                 ctx = NULL;  /* will be freed in callback */
2120         }
2121
2122         /* Success */
2123  out:
2124         hostkeys_update_ctx_free(ctx);
2125         sshkey_free(key);
2126         sshbuf_free(buf);
2127         /*
2128          * NB. Return success for all cases. The server doesn't need to know
2129          * what the client does with its hosts file.
2130          */
2131         return 1;
2132 }
2133
2134 static int
2135 client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
2136 {
2137         char *rtype;
2138         int want_reply;
2139         int success = 0;
2140
2141         rtype = packet_get_cstring(NULL);
2142         want_reply = packet_get_char();
2143         debug("client_input_global_request: rtype %s want_reply %d",
2144             rtype, want_reply);
2145         if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
2146                 success = client_input_hostkeys();
2147         if (want_reply) {
2148                 packet_start(success ?
2149                     SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
2150                 packet_send();
2151                 packet_write_wait();
2152         }
2153         free(rtype);
2154         return 0;
2155 }
2156
2157 void
2158 client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
2159     const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env)
2160 {
2161         int len;
2162         Channel *c = NULL;
2163
2164         debug2("%s: id %d", __func__, id);
2165
2166         if ((c = channel_lookup(ssh, id)) == NULL)
2167                 fatal("%s: channel %d: unknown channel", __func__, id);
2168
2169         packet_set_interactive(want_tty,
2170             options.ip_qos_interactive, options.ip_qos_bulk);
2171
2172         if (want_tty) {
2173                 struct winsize ws;
2174
2175                 /* Store window size in the packet. */
2176                 if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0)
2177                         memset(&ws, 0, sizeof(ws));
2178
2179                 channel_request_start(ssh, id, "pty-req", 1);
2180                 client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
2181                 packet_put_cstring(term != NULL ? term : "");
2182                 packet_put_int((u_int)ws.ws_col);
2183                 packet_put_int((u_int)ws.ws_row);
2184                 packet_put_int((u_int)ws.ws_xpixel);
2185                 packet_put_int((u_int)ws.ws_ypixel);
2186                 if (tiop == NULL)
2187                         tiop = get_saved_tio();
2188                 tty_make_modes(-1, tiop);
2189                 packet_send();
2190                 /* XXX wait for reply */
2191                 c->client_tty = 1;
2192         }
2193
2194         /* Transfer any environment variables from client to server */
2195         if (options.num_send_env != 0 && env != NULL) {
2196                 int i, j, matched;
2197                 char *name, *val;
2198
2199                 debug("Sending environment.");
2200                 for (i = 0; env[i] != NULL; i++) {
2201                         /* Split */
2202                         name = xstrdup(env[i]);
2203                         if ((val = strchr(name, '=')) == NULL) {
2204                                 free(name);
2205                                 continue;
2206                         }
2207                         *val++ = '\0';
2208
2209                         matched = 0;
2210                         for (j = 0; j < options.num_send_env; j++) {
2211                                 if (match_pattern(name, options.send_env[j])) {
2212                                         matched = 1;
2213                                         break;
2214                                 }
2215                         }
2216                         if (!matched) {
2217                                 debug3("Ignored env %s", name);
2218                                 free(name);
2219                                 continue;
2220                         }
2221
2222                         debug("Sending env %s = %s", name, val);
2223                         channel_request_start(ssh, id, "env", 0);
2224                         packet_put_cstring(name);
2225                         packet_put_cstring(val);
2226                         packet_send();
2227                         free(name);
2228                 }
2229         }
2230
2231         len = buffer_len(cmd);
2232         if (len > 0) {
2233                 if (len > 900)
2234                         len = 900;
2235                 if (want_subsystem) {
2236                         debug("Sending subsystem: %.*s",
2237                             len, (u_char*)buffer_ptr(cmd));
2238                         channel_request_start(ssh, id, "subsystem", 1);
2239                         client_expect_confirm(ssh, id, "subsystem",
2240                             CONFIRM_CLOSE);
2241                 } else {
2242                         debug("Sending command: %.*s",
2243                             len, (u_char*)buffer_ptr(cmd));
2244                         channel_request_start(ssh, id, "exec", 1);
2245                         client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
2246                 }
2247                 packet_put_string(buffer_ptr(cmd), buffer_len(cmd));
2248                 packet_send();
2249         } else {
2250                 channel_request_start(ssh, id, "shell", 1);
2251                 client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
2252                 packet_send();
2253         }
2254 }
2255
2256 static void
2257 client_init_dispatch(void)
2258 {
2259         dispatch_init(&dispatch_protocol_error);
2260
2261         dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
2262         dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
2263         dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
2264         dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
2265         dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
2266         dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2267         dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2268         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
2269         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
2270         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
2271         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
2272         dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
2273
2274         /* rekeying */
2275         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
2276
2277         /* global request reply messages */
2278         dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
2279         dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
2280 }
2281
2282 void
2283 client_stop_mux(void)
2284 {
2285         if (options.control_path != NULL && muxserver_sock != -1)
2286                 unlink(options.control_path);
2287         /*
2288          * If we are in persist mode, or don't have a shell, signal that we
2289          * should close when all active channels are closed.
2290          */
2291         if (options.control_persist || no_shell_flag) {
2292                 session_closed = 1;
2293                 setproctitle("[stopped mux]");
2294         }
2295 }
2296
2297 /* client specific fatal cleanup */
2298 void
2299 cleanup_exit(int i)
2300 {
2301         leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2302         leave_non_blocking();
2303         if (options.control_path != NULL && muxserver_sock != -1)
2304                 unlink(options.control_path);
2305         ssh_kill_proxy_command();
2306         _exit(i);
2307 }