crypto/openssh/serverloop.c

   1 /* $OpenBSD: serverloop.c,v 1.184 2016/03/07 19:02:43 djm 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  * Server main loop for handling the interactive session.
   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  * SSH2 support by Markus Friedl.
  15  * Copyright (c) 2000, 2001 Markus Friedl.  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 #include "includes.h"
  39
  40 #include <sys/param.h>  /* MIN MAX */
  41 #include <sys/types.h>
  42 #include <sys/wait.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47
  48 #include <netinet/in.h>
  49
  50 #include <errno.h>
  51 #include <fcntl.h>
  52 #include <pwd.h>
  53 #include <signal.h>
  54 #include <string.h>
  55 #include <termios.h>
  56 #include <unistd.h>
  57 #include <stdarg.h>
  58
  59 #include "openbsd-compat/sys-queue.h"
  60 #include "xmalloc.h"
  61 #include "packet.h"
  62 #include "buffer.h"
  63 #include "log.h"
  64 #include "misc.h"
  65 #include "servconf.h"
  66 #include "canohost.h"
  67 #include "sshpty.h"
  68 #include "channels.h"
  69 #include "compat.h"
  70 #include "ssh1.h"
  71 #include "ssh2.h"
  72 #include "key.h"
  73 #include "cipher.h"
  74 #include "kex.h"
  75 #include "hostfile.h"
  76 #include "auth.h"
  77 #include "session.h"
  78 #include "dispatch.h"
  79 #include "auth-options.h"
  80 #include "serverloop.h"
  81 #include "ssherr.h"
  82
  83 extern ServerOptions options;
  84
  85 /* XXX */
  86 extern Authctxt *the_authctxt;
  87 extern int use_privsep;
  88
  89 static Buffer stdin_buffer;     /* Buffer for stdin data. */
  90 static Buffer stdout_buffer;    /* Buffer for stdout data. */
  91 static Buffer stderr_buffer;    /* Buffer for stderr data. */
  92 static int fdin;                /* Descriptor for stdin (for writing) */
  93 static int fdout;               /* Descriptor for stdout (for reading);
  94                                    May be same number as fdin. */
  95 static int fderr;               /* Descriptor for stderr.  May be -1. */
  96 static long stdin_bytes = 0;    /* Number of bytes written to stdin. */
  97 static long stdout_bytes = 0;   /* Number of stdout bytes sent to client. */
  98 static long stderr_bytes = 0;   /* Number of stderr bytes sent to client. */
  99 static long fdout_bytes = 0;    /* Number of stdout bytes read from program. */
 100 static int stdin_eof = 0;       /* EOF message received from client. */
 101 static int fdout_eof = 0;       /* EOF encountered reading from fdout. */
 102 static int fderr_eof = 0;       /* EOF encountered readung from fderr. */
 103 static int fdin_is_tty = 0;     /* fdin points to a tty. */
 104 static int connection_in;       /* Connection to client (input). */
 105 static int connection_out;      /* Connection to client (output). */
 106 static int connection_closed = 0;       /* Connection to client closed. */
 107 static u_int buffer_high;       /* "Soft" max buffer size. */
 108 static int no_more_sessions = 0; /* Disallow further sessions. */
 109
 110 /*
 111  * This SIGCHLD kludge is used to detect when the child exits.  The server
 112  * will exit after that, as soon as forwarded connections have terminated.
 113  */
 114
 115 static volatile sig_atomic_t child_terminated = 0;      /* The child has terminated. */
 116
 117 /* Cleanup on signals (!use_privsep case only) */
 118 static volatile sig_atomic_t received_sigterm = 0;
 119
 120 /* prototypes */
 121 static void server_init_dispatch(void);
 122
 123 /*
 124  * we write to this pipe if a SIGCHLD is caught in order to avoid
 125  * the race between select() and child_terminated
 126  */
 127 static int notify_pipe[2];
 128 static void
 129 notify_setup(void)
 130 {
 131         if (pipe(notify_pipe) < 0) {
 132                 error("pipe(notify_pipe) failed %s", strerror(errno));
 133         } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
 134             (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
 135                 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
 136                 close(notify_pipe[0]);
 137                 close(notify_pipe[1]);
 138         } else {
 139                 set_nonblock(notify_pipe[0]);
 140                 set_nonblock(notify_pipe[1]);
 141                 return;
 142         }
 143         notify_pipe[0] = -1;    /* read end */
 144         notify_pipe[1] = -1;    /* write end */
 145 }
 146 static void
 147 notify_parent(void)
 148 {
 149         if (notify_pipe[1] != -1)
 150                 (void)write(notify_pipe[1], "", 1);
 151 }
 152 static void
 153 notify_prepare(fd_set *readset)
 154 {
 155         if (notify_pipe[0] != -1)
 156                 FD_SET(notify_pipe[0], readset);
 157 }
 158 static void
 159 notify_done(fd_set *readset)
 160 {
 161         char c;
 162
 163         if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
 164                 while (read(notify_pipe[0], &c, 1) != -1)
 165                         debug2("notify_done: reading");
 166 }
 167
 168 /*ARGSUSED*/
 169 static void
 170 sigchld_handler(int sig)
 171 {
 172         int save_errno = errno;
 173         child_terminated = 1;
 174 #ifndef _UNICOS
 175         mysignal(SIGCHLD, sigchld_handler);
 176 #endif
 177         notify_parent();
 178         errno = save_errno;
 179 }
 180
 181 /*ARGSUSED*/
 182 static void
 183 sigterm_handler(int sig)
 184 {
 185         received_sigterm = sig;
 186 }
 187
 188 /*
 189  * Make packets from buffered stderr data, and buffer it for sending
 190  * to the client.
 191  */
 192 static void
 193 make_packets_from_stderr_data(void)
 194 {
 195         u_int len;
 196
 197         /* Send buffered stderr data to the client. */
 198         while (buffer_len(&stderr_buffer) > 0 &&
 199             packet_not_very_much_data_to_write()) {
 200                 len = buffer_len(&stderr_buffer);
 201                 if (packet_is_interactive()) {
 202                         if (len > 512)
 203                                 len = 512;
 204                 } else {
 205                         /* Keep the packets at reasonable size. */
 206                         if (len > packet_get_maxsize())
 207                                 len = packet_get_maxsize();
 208                 }
 209                 packet_start(SSH_SMSG_STDERR_DATA);
 210                 packet_put_string(buffer_ptr(&stderr_buffer), len);
 211                 packet_send();
 212                 buffer_consume(&stderr_buffer, len);
 213                 stderr_bytes += len;
 214         }
 215 }
 216
 217 /*
 218  * Make packets from buffered stdout data, and buffer it for sending to the
 219  * client.
 220  */
 221 static void
 222 make_packets_from_stdout_data(void)
 223 {
 224         u_int len;
 225
 226         /* Send buffered stdout data to the client. */
 227         while (buffer_len(&stdout_buffer) > 0 &&
 228             packet_not_very_much_data_to_write()) {
 229                 len = buffer_len(&stdout_buffer);
 230                 if (packet_is_interactive()) {
 231                         if (len > 512)
 232                                 len = 512;
 233                 } else {
 234                         /* Keep the packets at reasonable size. */
 235                         if (len > packet_get_maxsize())
 236                                 len = packet_get_maxsize();
 237                 }
 238                 packet_start(SSH_SMSG_STDOUT_DATA);
 239                 packet_put_string(buffer_ptr(&stdout_buffer), len);
 240                 packet_send();
 241                 buffer_consume(&stdout_buffer, len);
 242                 stdout_bytes += len;
 243         }
 244 }
 245
 246 static void
 247 client_alive_check(void)
 248 {
 249         int channel_id;
 250
 251         /* timeout, check to see how many we have had */
 252         if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
 253                 logit("Timeout, client not responding.");
 254                 cleanup_exit(255);
 255         }
 256
 257         /*
 258          * send a bogus global/channel request with "wantreply",
 259          * we should get back a failure
 260          */
 261         if ((channel_id = channel_find_open()) == -1) {
 262                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
 263                 packet_put_cstring("keepalive@openssh.com");
 264                 packet_put_char(1);     /* boolean: want reply */
 265         } else {
 266                 channel_request_start(channel_id, "keepalive@openssh.com", 1);
 267         }
 268         packet_send();
 269 }
 270
 271 /*
 272  * Sleep in select() until we can do something.  This will initialize the
 273  * select masks.  Upon return, the masks will indicate which descriptors
 274  * have data or can accept data.  Optionally, a maximum time can be specified
 275  * for the duration of the wait (0 = infinite).
 276  */
 277 static void
 278 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 279     u_int *nallocp, u_int64_t max_time_ms)
 280 {
 281         struct timeval tv, *tvp;
 282         int ret;
 283         time_t minwait_secs = 0;
 284         int client_alive_scheduled = 0;
 285         int program_alive_scheduled = 0;
 286
 287         /* Allocate and update select() masks for channel descriptors. */
 288         channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
 289             &minwait_secs, 0);
 290
 291         /* XXX need proper deadline system for rekey/client alive */
 292         if (minwait_secs != 0)
 293                 max_time_ms = MIN(max_time_ms, (u_int)minwait_secs * 1000);
 294
 295         /*
 296          * if using client_alive, set the max timeout accordingly,
 297          * and indicate that this particular timeout was for client
 298          * alive by setting the client_alive_scheduled flag.
 299          *
 300          * this could be randomized somewhat to make traffic
 301          * analysis more difficult, but we're not doing it yet.
 302          */
 303         if (compat20 && options.client_alive_interval) {
 304                 uint64_t keepalive_ms =
 305                     (uint64_t)options.client_alive_interval * 1000;
 306
 307                 client_alive_scheduled = 1;
 308                 if (max_time_ms == 0 || max_time_ms > keepalive_ms)
 309                         max_time_ms = keepalive_ms;
 310         }
 311
 312         if (compat20) {
 313 #if 0
 314                 /* wrong: bad condition XXX */
 315                 if (channel_not_very_much_buffered_data())
 316 #endif
 317                 FD_SET(connection_in, *readsetp);
 318         } else {
 319                 /*
 320                  * Read packets from the client unless we have too much
 321                  * buffered stdin or channel data.
 322                  */
 323                 if (buffer_len(&stdin_buffer) < buffer_high &&
 324                     channel_not_very_much_buffered_data())
 325                         FD_SET(connection_in, *readsetp);
 326                 /*
 327                  * If there is not too much data already buffered going to
 328                  * the client, try to get some more data from the program.
 329                  */
 330                 if (packet_not_very_much_data_to_write()) {
 331                         program_alive_scheduled = child_terminated;
 332                         if (!fdout_eof)
 333                                 FD_SET(fdout, *readsetp);
 334                         if (!fderr_eof)
 335                                 FD_SET(fderr, *readsetp);
 336                 }
 337                 /*
 338                  * If we have buffered data, try to write some of that data
 339                  * to the program.
 340                  */
 341                 if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
 342                         FD_SET(fdin, *writesetp);
 343         }
 344         notify_prepare(*readsetp);
 345
 346         /*
 347          * If we have buffered packet data going to the client, mark that
 348          * descriptor.
 349          */
 350         if (packet_have_data_to_write())
 351                 FD_SET(connection_out, *writesetp);
 352
 353         /*
 354          * If child has terminated and there is enough buffer space to read
 355          * from it, then read as much as is available and exit.
 356          */
 357         if (child_terminated && packet_not_very_much_data_to_write())
 358                 if (max_time_ms == 0 || client_alive_scheduled)
 359                         max_time_ms = 100;
 360
 361         if (max_time_ms == 0)
 362                 tvp = NULL;
 363         else {
 364                 tv.tv_sec = max_time_ms / 1000;
 365                 tv.tv_usec = 1000 * (max_time_ms % 1000);
 366                 tvp = &tv;
 367         }
 368
 369         /* Wait for something to happen, or the timeout to expire. */
 370         ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
 371
 372         if (ret == -1) {
 373                 memset(*readsetp, 0, *nallocp);
 374                 memset(*writesetp, 0, *nallocp);
 375                 if (errno != EINTR)
 376                         error("select: %.100s", strerror(errno));
 377         } else {
 378                 if (ret == 0 && client_alive_scheduled)
 379                         client_alive_check();
 380                 if (!compat20 && program_alive_scheduled && fdin_is_tty) {
 381                         if (!fdout_eof)
 382                                 FD_SET(fdout, *readsetp);
 383                         if (!fderr_eof)
 384                                 FD_SET(fderr, *readsetp);
 385                 }
 386         }
 387
 388         notify_done(*readsetp);
 389 }
 390
 391 /*
 392  * Processes input from the client and the program.  Input data is stored
 393  * in buffers and processed later.
 394  */
 395 static void
 396 process_input(fd_set *readset)
 397 {
 398         struct ssh *ssh = active_state; /* XXX */
 399         int len;
 400         char buf[16384];
 401
 402         /* Read and buffer any input data from the client. */
 403         if (FD_ISSET(connection_in, readset)) {
 404                 len = read(connection_in, buf, sizeof(buf));
 405                 if (len == 0) {
 406                         verbose("Connection closed by %.100s port %d",
 407                             ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
 408                         connection_closed = 1;
 409                         if (compat20)
 410                                 return;
 411                         cleanup_exit(255);
 412                 } else if (len < 0) {
 413                         if (errno != EINTR && errno != EAGAIN &&
 414                             errno != EWOULDBLOCK) {
 415                                 verbose("Read error from remote host "
 416                                     "%.100s port %d: %.100s",
 417                                     ssh_remote_ipaddr(ssh),
 418                                     ssh_remote_port(ssh), strerror(errno));
 419                                 cleanup_exit(255);
 420                         }
 421                 } else {
 422                         /* Buffer any received data. */
 423                         packet_process_incoming(buf, len);
 424                 }
 425         }
 426         if (compat20)
 427                 return;
 428
 429         /* Read and buffer any available stdout data from the program. */
 430         if (!fdout_eof && FD_ISSET(fdout, readset)) {
 431                 errno = 0;
 432                 len = read(fdout, buf, sizeof(buf));
 433                 if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
 434                     errno == EWOULDBLOCK) && !child_terminated))) {
 435                         /* do nothing */
 436 #ifndef PTY_ZEROREAD
 437                 } else if (len <= 0) {
 438 #else
 439                 } else if ((!isatty(fdout) && len <= 0) ||
 440                     (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) {
 441 #endif
 442                         fdout_eof = 1;
 443                 } else {
 444                         buffer_append(&stdout_buffer, buf, len);
 445                         fdout_bytes += len;
 446                 }
 447         }
 448         /* Read and buffer any available stderr data from the program. */
 449         if (!fderr_eof && FD_ISSET(fderr, readset)) {
 450                 errno = 0;
 451                 len = read(fderr, buf, sizeof(buf));
 452                 if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
 453                     errno == EWOULDBLOCK) && !child_terminated))) {
 454                         /* do nothing */
 455 #ifndef PTY_ZEROREAD
 456                 } else if (len <= 0) {
 457 #else
 458                 } else if ((!isatty(fderr) && len <= 0) ||
 459                     (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) {
 460 #endif
 461                         fderr_eof = 1;
 462                 } else {
 463                         buffer_append(&stderr_buffer, buf, len);
 464                 }
 465         }
 466 }
 467
 468 /*
 469  * Sends data from internal buffers to client program stdin.
 470  */
 471 static void
 472 process_output(fd_set *writeset)
 473 {
 474         struct termios tio;
 475         u_char *data;
 476         u_int dlen;
 477         int len;
 478
 479         /* Write buffered data to program stdin. */
 480         if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
 481                 data = buffer_ptr(&stdin_buffer);
 482                 dlen = buffer_len(&stdin_buffer);
 483                 len = write(fdin, data, dlen);
 484                 if (len < 0 &&
 485                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) {
 486                         /* do nothing */
 487                 } else if (len <= 0) {
 488                         if (fdin != fdout)
 489                                 close(fdin);
 490                         else
 491                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 492                         fdin = -1;
 493                 } else {
 494                         /* Successful write. */
 495                         if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
 496                             tcgetattr(fdin, &tio) == 0 &&
 497                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
 498                                 /*
 499                                  * Simulate echo to reduce the impact of
 500                                  * traffic analysis
 501                                  */
 502                                 packet_send_ignore(len);
 503                                 packet_send();
 504                         }
 505                         /* Consume the data from the buffer. */
 506                         buffer_consume(&stdin_buffer, len);
 507                         /* Update the count of bytes written to the program. */
 508                         stdin_bytes += len;
 509                 }
 510         }
 511         /* Send any buffered packet data to the client. */
 512         if (FD_ISSET(connection_out, writeset))
 513                 packet_write_poll();
 514 }
 515
 516 /*
 517  * Wait until all buffered output has been sent to the client.
 518  * This is used when the program terminates.
 519  */
 520 static void
 521 drain_output(void)
 522 {
 523         /* Send any buffered stdout data to the client. */
 524         if (buffer_len(&stdout_buffer) > 0) {
 525                 packet_start(SSH_SMSG_STDOUT_DATA);
 526                 packet_put_string(buffer_ptr(&stdout_buffer),
 527                                   buffer_len(&stdout_buffer));
 528                 packet_send();
 529                 /* Update the count of sent bytes. */
 530                 stdout_bytes += buffer_len(&stdout_buffer);
 531         }
 532         /* Send any buffered stderr data to the client. */
 533         if (buffer_len(&stderr_buffer) > 0) {
 534                 packet_start(SSH_SMSG_STDERR_DATA);
 535                 packet_put_string(buffer_ptr(&stderr_buffer),
 536                                   buffer_len(&stderr_buffer));
 537                 packet_send();
 538                 /* Update the count of sent bytes. */
 539                 stderr_bytes += buffer_len(&stderr_buffer);
 540         }
 541         /* Wait until all buffered data has been written to the client. */
 542         packet_write_wait();
 543 }
 544
 545 static void
 546 process_buffered_input_packets(void)
 547 {
 548         dispatch_run(DISPATCH_NONBLOCK, NULL, active_state);
 549 }
 550
 551 /*
 552  * Performs the interactive session.  This handles data transmission between
 553  * the client and the program.  Note that the notion of stdin, stdout, and
 554  * stderr in this function is sort of reversed: this function writes to
 555  * stdin (of the child program), and reads from stdout and stderr (of the
 556  * child program).
 557  */
 558 void
 559 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
 560 {
 561         fd_set *readset = NULL, *writeset = NULL;
 562         int max_fd = 0;
 563         u_int nalloc = 0;
 564         int wait_status;        /* Status returned by wait(). */
 565         pid_t wait_pid;         /* pid returned by wait(). */
 566         int waiting_termination = 0;    /* Have displayed waiting close message. */
 567         u_int64_t max_time_milliseconds;
 568         u_int previous_stdout_buffer_bytes;
 569         u_int stdout_buffer_bytes;
 570         int type;
 571
 572         debug("Entering interactive session.");
 573
 574         /* Initialize the SIGCHLD kludge. */
 575         child_terminated = 0;
 576         mysignal(SIGCHLD, sigchld_handler);
 577
 578         if (!use_privsep) {
 579                 signal(SIGTERM, sigterm_handler);
 580                 signal(SIGINT, sigterm_handler);
 581                 signal(SIGQUIT, sigterm_handler);
 582         }
 583
 584         /* Initialize our global variables. */
 585         fdin = fdin_arg;
 586         fdout = fdout_arg;
 587         fderr = fderr_arg;
 588
 589         /* nonblocking IO */
 590         set_nonblock(fdin);
 591         set_nonblock(fdout);
 592         /* we don't have stderr for interactive terminal sessions, see below */
 593         if (fderr != -1)
 594                 set_nonblock(fderr);
 595
 596         if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
 597                 fdin_is_tty = 1;
 598
 599         connection_in = packet_get_connection_in();
 600         connection_out = packet_get_connection_out();
 601
 602         notify_setup();
 603
 604         previous_stdout_buffer_bytes = 0;
 605
 606         /* Set approximate I/O buffer size. */
 607         if (packet_is_interactive())
 608                 buffer_high = 4096;
 609         else
 610                 buffer_high = 64 * 1024;
 611
 612 #if 0
 613         /* Initialize max_fd to the maximum of the known file descriptors. */
 614         max_fd = MAX(connection_in, connection_out);
 615         max_fd = MAX(max_fd, fdin);
 616         max_fd = MAX(max_fd, fdout);
 617         if (fderr != -1)
 618                 max_fd = MAX(max_fd, fderr);
 619 #endif
 620
 621         /* Initialize Initialize buffers. */
 622         buffer_init(&stdin_buffer);
 623         buffer_init(&stdout_buffer);
 624         buffer_init(&stderr_buffer);
 625
 626         /*
 627          * If we have no separate fderr (which is the case when we have a pty
 628          * - there we cannot make difference between data sent to stdout and
 629          * stderr), indicate that we have seen an EOF from stderr.  This way
 630          * we don't need to check the descriptor everywhere.
 631          */
 632         if (fderr == -1)
 633                 fderr_eof = 1;
 634
 635         server_init_dispatch();
 636
 637         /* Main loop of the server for the interactive session mode. */
 638         for (;;) {
 639
 640                 /* Process buffered packets from the client. */
 641                 process_buffered_input_packets();
 642
 643                 /*
 644                  * If we have received eof, and there is no more pending
 645                  * input data, cause a real eof by closing fdin.
 646                  */
 647                 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
 648                         if (fdin != fdout)
 649                                 close(fdin);
 650                         else
 651                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 652                         fdin = -1;
 653                 }
 654                 /* Make packets from buffered stderr data to send to the client. */
 655                 make_packets_from_stderr_data();
 656
 657                 /*
 658                  * Make packets from buffered stdout data to send to the
 659                  * client. If there is very little to send, this arranges to
 660                  * not send them now, but to wait a short while to see if we
 661                  * are getting more data. This is necessary, as some systems
 662                  * wake up readers from a pty after each separate character.
 663                  */
 664                 max_time_milliseconds = 0;
 665                 stdout_buffer_bytes = buffer_len(&stdout_buffer);
 666                 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
 667                     stdout_buffer_bytes != previous_stdout_buffer_bytes) {
 668                         /* try again after a while */
 669                         max_time_milliseconds = 10;
 670                 } else {
 671                         /* Send it now. */
 672                         make_packets_from_stdout_data();
 673                 }
 674                 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
 675
 676                 /* Send channel data to the client. */
 677                 if (packet_not_very_much_data_to_write())
 678                         channel_output_poll();
 679
 680                 /*
 681                  * Bail out of the loop if the program has closed its output
 682                  * descriptors, and we have no more data to send to the
 683                  * client, and there is no pending buffered data.
 684                  */
 685                 if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
 686                     buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
 687                         if (!channel_still_open())
 688                                 break;
 689                         if (!waiting_termination) {
 690                                 const char *s = "Waiting for forwarded connections to terminate...\r\n";
 691                                 char *cp;
 692                                 waiting_termination = 1;
 693                                 buffer_append(&stderr_buffer, s, strlen(s));
 694
 695                                 /* Display list of open channels. */
 696                                 cp = channel_open_message();
 697                                 buffer_append(&stderr_buffer, cp, strlen(cp));
 698                                 free(cp);
 699                         }
 700                 }
 701                 max_fd = MAX(connection_in, connection_out);
 702                 max_fd = MAX(max_fd, fdin);
 703                 max_fd = MAX(max_fd, fdout);
 704                 max_fd = MAX(max_fd, fderr);
 705                 max_fd = MAX(max_fd, notify_pipe[0]);
 706
 707                 /* Sleep in select() until we can do something. */
 708                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 709                     &nalloc, max_time_milliseconds);
 710
 711                 if (received_sigterm) {
 712                         logit("Exiting on signal %d", (int)received_sigterm);
 713                         /* Clean up sessions, utmp, etc. */
 714                         cleanup_exit(255);
 715                 }
 716
 717                 /* Process any channel events. */
 718                 channel_after_select(readset, writeset);
 719
 720                 /* Process input from the client and from program stdout/stderr. */
 721                 process_input(readset);
 722
 723                 /* Process output to the client and to program stdin. */
 724                 process_output(writeset);
 725         }
 726         free(readset);
 727         free(writeset);
 728
 729         /* Cleanup and termination code. */
 730
 731         /* Wait until all output has been sent to the client. */
 732         drain_output();
 733
 734         debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
 735             stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
 736
 737         /* Free and clear the buffers. */
 738         buffer_free(&stdin_buffer);
 739         buffer_free(&stdout_buffer);
 740         buffer_free(&stderr_buffer);
 741
 742         /* Close the file descriptors. */
 743         if (fdout != -1)
 744                 close(fdout);
 745         fdout = -1;
 746         fdout_eof = 1;
 747         if (fderr != -1)
 748                 close(fderr);
 749         fderr = -1;
 750         fderr_eof = 1;
 751         if (fdin != -1)
 752                 close(fdin);
 753         fdin = -1;
 754
 755         channel_free_all();
 756
 757         /* We no longer want our SIGCHLD handler to be called. */
 758         mysignal(SIGCHLD, SIG_DFL);
 759
 760         while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
 761                 if (errno != EINTR)
 762                         packet_disconnect("wait: %.100s", strerror(errno));
 763         if (wait_pid != pid)
 764                 error("Strange, wait returned pid %ld, expected %ld",
 765                     (long)wait_pid, (long)pid);
 766
 767         /* Check if it exited normally. */
 768         if (WIFEXITED(wait_status)) {
 769                 /* Yes, normal exit.  Get exit status and send it to the client. */
 770                 debug("Command exited with status %d.", WEXITSTATUS(wait_status));
 771                 packet_start(SSH_SMSG_EXITSTATUS);
 772                 packet_put_int(WEXITSTATUS(wait_status));
 773                 packet_send();
 774                 packet_write_wait();
 775
 776                 /*
 777                  * Wait for exit confirmation.  Note that there might be
 778                  * other packets coming before it; however, the program has
 779                  * already died so we just ignore them.  The client is
 780                  * supposed to respond with the confirmation when it receives
 781                  * the exit status.
 782                  */
 783                 do {
 784                         type = packet_read();
 785                 }
 786                 while (type != SSH_CMSG_EXIT_CONFIRMATION);
 787
 788                 debug("Received exit confirmation.");
 789                 return;
 790         }
 791         /* Check if the program terminated due to a signal. */
 792         if (WIFSIGNALED(wait_status))
 793                 packet_disconnect("Command terminated on signal %d.",
 794                                   WTERMSIG(wait_status));
 795
 796         /* Some weird exit cause.  Just exit. */
 797         packet_disconnect("wait returned status %04x.", wait_status);
 798         /* NOTREACHED */
 799 }
 800
 801 static void
 802 collect_children(void)
 803 {
 804         pid_t pid;
 805         sigset_t oset, nset;
 806         int status;
 807
 808         /* block SIGCHLD while we check for dead children */
 809         sigemptyset(&nset);
 810         sigaddset(&nset, SIGCHLD);
 811         sigprocmask(SIG_BLOCK, &nset, &oset);
 812         if (child_terminated) {
 813                 debug("Received SIGCHLD.");
 814                 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 815                     (pid < 0 && errno == EINTR))
 816                         if (pid > 0)
 817                                 session_close_by_pid(pid, status);
 818                 child_terminated = 0;
 819         }
 820         sigprocmask(SIG_SETMASK, &oset, NULL);
 821 }
 822
 823 void
 824 server_loop2(Authctxt *authctxt)
 825 {
 826         fd_set *readset = NULL, *writeset = NULL;
 827         int max_fd;
 828         u_int nalloc = 0;
 829         u_int64_t rekey_timeout_ms = 0;
 830
 831         debug("Entering interactive session for SSH2.");
 832
 833         mysignal(SIGCHLD, sigchld_handler);
 834         child_terminated = 0;
 835         connection_in = packet_get_connection_in();
 836         connection_out = packet_get_connection_out();
 837
 838         if (!use_privsep) {
 839                 signal(SIGTERM, sigterm_handler);
 840                 signal(SIGINT, sigterm_handler);
 841                 signal(SIGQUIT, sigterm_handler);
 842         }
 843
 844         notify_setup();
 845
 846         max_fd = MAX(connection_in, connection_out);
 847         max_fd = MAX(max_fd, notify_pipe[0]);
 848
 849         server_init_dispatch();
 850
 851         for (;;) {
 852                 process_buffered_input_packets();
 853
 854                 if (!ssh_packet_is_rekeying(active_state) &&
 855                     packet_not_very_much_data_to_write())
 856                         channel_output_poll();
 857                 if (options.rekey_interval > 0 && compat20 &&
 858                     !ssh_packet_is_rekeying(active_state))
 859                         rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
 860                 else
 861                         rekey_timeout_ms = 0;
 862
 863                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 864                     &nalloc, rekey_timeout_ms);
 865
 866                 if (received_sigterm) {
 867                         logit("Exiting on signal %d", (int)received_sigterm);
 868                         /* Clean up sessions, utmp, etc. */
 869                         cleanup_exit(255);
 870                 }
 871
 872                 collect_children();
 873                 if (!ssh_packet_is_rekeying(active_state))
 874                         channel_after_select(readset, writeset);
 875                 process_input(readset);
 876                 if (connection_closed)
 877                         break;
 878                 process_output(writeset);
 879         }
 880         collect_children();
 881
 882         free(readset);
 883         free(writeset);
 884
 885         /* free all channels, no more reads and writes */
 886         channel_free_all();
 887
 888         /* free remaining sessions, e.g. remove wtmp entries */
 889         session_destroy_all(NULL);
 890 }
 891
 892 static int
 893 server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
 894 {
 895         debug("Got %d/%u for keepalive", type, seq);
 896         /*
 897          * reset timeout, since we got a sane answer from the client.
 898          * even if this was generated by something other than
 899          * the bogus CHANNEL_REQUEST we send for keepalives.
 900          */
 901         packet_set_alive_timeouts(0);
 902         return 0;
 903 }
 904
 905 static int
 906 server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
 907 {
 908         char *data;
 909         u_int data_len;
 910
 911         /* Stdin data from the client.  Append it to the buffer. */
 912         /* Ignore any data if the client has closed stdin. */
 913         if (fdin == -1)
 914                 return 0;
 915         data = packet_get_string(&data_len);
 916         packet_check_eom();
 917         buffer_append(&stdin_buffer, data, data_len);
 918         explicit_bzero(data, data_len);
 919         free(data);
 920         return 0;
 921 }
 922
 923 static int
 924 server_input_eof(int type, u_int32_t seq, void *ctxt)
 925 {
 926         /*
 927          * Eof from the client.  The stdin descriptor to the
 928          * program will be closed when all buffered data has
 929          * drained.
 930          */
 931         debug("EOF received for stdin.");
 932         packet_check_eom();
 933         stdin_eof = 1;
 934         return 0;
 935 }
 936
 937 static int
 938 server_input_window_size(int type, u_int32_t seq, void *ctxt)
 939 {
 940         u_int row = packet_get_int();
 941         u_int col = packet_get_int();
 942         u_int xpixel = packet_get_int();
 943         u_int ypixel = packet_get_int();
 944
 945         debug("Window change received.");
 946         packet_check_eom();
 947         if (fdin != -1)
 948                 pty_change_window_size(fdin, row, col, xpixel, ypixel);
 949         return 0;
 950 }
 951
 952 static Channel *
 953 server_request_direct_tcpip(void)
 954 {
 955         Channel *c = NULL;
 956         char *target, *originator;
 957         u_short target_port, originator_port;
 958
 959         target = packet_get_string(NULL);
 960         target_port = packet_get_int();
 961         originator = packet_get_string(NULL);
 962         originator_port = packet_get_int();
 963         packet_check_eom();
 964
 965         debug("server_request_direct_tcpip: originator %s port %d, target %s "
 966             "port %d", originator, originator_port, target, target_port);
 967
 968         /* XXX fine grained permissions */
 969         if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
 970             !no_port_forwarding_flag) {
 971                 c = channel_connect_to_port(target, target_port,
 972                     "direct-tcpip", "direct-tcpip");
 973         } else {
 974                 logit("refused local port forward: "
 975                     "originator %s port %d, target %s port %d",
 976                     originator, originator_port, target, target_port);
 977         }
 978
 979         free(originator);
 980         free(target);
 981
 982         return c;
 983 }
 984
 985 static Channel *
 986 server_request_direct_streamlocal(void)
 987 {
 988         Channel *c = NULL;
 989         char *target, *originator;
 990         u_short originator_port;
 991
 992         target = packet_get_string(NULL);
 993         originator = packet_get_string(NULL);
 994         originator_port = packet_get_int();
 995         packet_check_eom();
 996
 997         debug("server_request_direct_streamlocal: originator %s port %d, target %s",
 998             originator, originator_port, target);
 999
1000         /* XXX fine grained permissions */
1001         if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
1002             !no_port_forwarding_flag) {
1003                 c = channel_connect_to_path(target,
1004                     "direct-streamlocal@openssh.com", "direct-streamlocal");
1005         } else {
1006                 logit("refused streamlocal port forward: "
1007                     "originator %s port %d, target %s",
1008                     originator, originator_port, target);
1009         }
1010
1011         free(originator);
1012         free(target);
1013
1014         return c;
1015 }
1016
1017 static Channel *
1018 server_request_tun(void)
1019 {
1020         Channel *c = NULL;
1021         int mode, tun;
1022         int sock;
1023
1024         mode = packet_get_int();
1025         switch (mode) {
1026         case SSH_TUNMODE_POINTOPOINT:
1027         case SSH_TUNMODE_ETHERNET:
1028                 break;
1029         default:
1030                 packet_send_debug("Unsupported tunnel device mode.");
1031                 return NULL;
1032         }
1033         if ((options.permit_tun & mode) == 0) {
1034                 packet_send_debug("Server has rejected tunnel device "
1035                     "forwarding");
1036                 return NULL;
1037         }
1038
1039         tun = packet_get_int();
1040         if (forced_tun_device != -1) {
1041                 if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
1042                         goto done;
1043                 tun = forced_tun_device;
1044         }
1045         sock = tun_open(tun, mode);
1046         if (sock < 0)
1047                 goto done;
1048         c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
1049             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1050         c->datagram = 1;
1051 #if defined(SSH_TUN_FILTER)
1052         if (mode == SSH_TUNMODE_POINTOPOINT)
1053                 channel_register_filter(c->self, sys_tun_infilter,
1054                     sys_tun_outfilter, NULL, NULL);
1055 #endif
1056
1057  done:
1058         if (c == NULL)
1059                 packet_send_debug("Failed to open the tunnel device.");
1060         return c;
1061 }
1062
1063 static Channel *
1064 server_request_session(void)
1065 {
1066         Channel *c;
1067
1068         debug("input_session_request");
1069         packet_check_eom();
1070
1071         if (no_more_sessions) {
1072                 packet_disconnect("Possible attack: attempt to open a session "
1073                     "after additional sessions disabled");
1074         }
1075
1076         /*
1077          * A server session has no fd to read or write until a
1078          * CHANNEL_REQUEST for a shell is made, so we set the type to
1079          * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
1080          * CHANNEL_REQUEST messages is registered.
1081          */
1082         c = channel_new("session", SSH_CHANNEL_LARVAL,
1083             -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
1084             0, "server-session", 1);
1085         if (session_open(the_authctxt, c->self) != 1) {
1086                 debug("session open failed, free channel %d", c->self);
1087                 channel_free(c);
1088                 return NULL;
1089         }
1090         channel_register_cleanup(c->self, session_close_by_channel, 0);
1091         return c;
1092 }
1093
1094 static int
1095 server_input_channel_open(int type, u_int32_t seq, void *ctxt)
1096 {
1097         Channel *c = NULL;
1098         char *ctype;
1099         int rchan;
1100         u_int rmaxpack, rwindow, len;
1101
1102         ctype = packet_get_string(&len);
1103         rchan = packet_get_int();
1104         rwindow = packet_get_int();
1105         rmaxpack = packet_get_int();
1106
1107         debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
1108             ctype, rchan, rwindow, rmaxpack);
1109
1110         if (strcmp(ctype, "session") == 0) {
1111                 c = server_request_session();
1112         } else if (strcmp(ctype, "direct-tcpip") == 0) {
1113                 c = server_request_direct_tcpip();
1114         } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
1115                 c = server_request_direct_streamlocal();
1116         } else if (strcmp(ctype, "tun@openssh.com") == 0) {
1117                 c = server_request_tun();
1118         }
1119         if (c != NULL) {
1120                 debug("server_input_channel_open: confirm %s", ctype);
1121                 c->remote_id = rchan;
1122                 c->remote_window = rwindow;
1123                 c->remote_maxpacket = rmaxpack;
1124                 if (c->type != SSH_CHANNEL_CONNECTING) {
1125                         packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1126                         packet_put_int(c->remote_id);
1127                         packet_put_int(c->self);
1128                         packet_put_int(c->local_window);
1129                         packet_put_int(c->local_maxpacket);
1130                         packet_send();
1131                 }
1132         } else {
1133                 debug("server_input_channel_open: failure %s", ctype);
1134                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1135                 packet_put_int(rchan);
1136                 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1137                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1138                         packet_put_cstring("open failed");
1139                         packet_put_cstring("");
1140                 }
1141                 packet_send();
1142         }
1143         free(ctype);
1144         return 0;
1145 }
1146
1147 static int
1148 server_input_hostkeys_prove(struct sshbuf **respp)
1149 {
1150         struct ssh *ssh = active_state; /* XXX */
1151         struct sshbuf *resp = NULL;
1152         struct sshbuf *sigbuf = NULL;
1153         struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
1154         int r, ndx, success = 0;
1155         const u_char *blob;
1156         u_char *sig = 0;
1157         size_t blen, slen;
1158
1159         if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
1160                 fatal("%s: sshbuf_new", __func__);
1161
1162         while (ssh_packet_remaining(ssh) > 0) {
1163                 sshkey_free(key);
1164                 key = NULL;
1165                 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
1166                     (r = sshkey_from_blob(blob, blen, &key)) != 0) {
1167                         error("%s: couldn't parse key: %s",
1168                             __func__, ssh_err(r));
1169                         goto out;
1170                 }
1171                 /*
1172                  * Better check that this is actually one of our hostkeys
1173                  * before attempting to sign anything with it.
1174                  */
1175                 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
1176                         error("%s: unknown host %s key",
1177                             __func__, sshkey_type(key));
1178                         goto out;
1179                 }
1180                 /*
1181                  * XXX refactor: make kex->sign just use an index rather
1182                  * than passing in public and private keys
1183                  */
1184                 if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
1185                     (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
1186                         error("%s: can't retrieve hostkey %d", __func__, ndx);
1187                         goto out;
1188                 }
1189                 sshbuf_reset(sigbuf);
1190                 free(sig);
1191                 sig = NULL;
1192                 if ((r = sshbuf_put_cstring(sigbuf,
1193                     "hostkeys-prove-00@openssh.com")) != 0 ||
1194                     (r = sshbuf_put_string(sigbuf,
1195                     ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
1196                     (r = sshkey_puts(key, sigbuf)) != 0 ||
1197                     (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
1198                     sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 ||
1199                     (r = sshbuf_put_string(resp, sig, slen)) != 0) {
1200                         error("%s: couldn't prepare signature: %s",
1201                             __func__, ssh_err(r));
1202                         goto out;
1203                 }
1204         }
1205         /* Success */
1206         *respp = resp;
1207         resp = NULL; /* don't free it */
1208         success = 1;
1209  out:
1210         free(sig);
1211         sshbuf_free(resp);
1212         sshbuf_free(sigbuf);
1213         sshkey_free(key);
1214         return success;
1215 }
1216
1217 static int
1218 server_input_global_request(int type, u_int32_t seq, void *ctxt)
1219 {
1220         char *rtype;
1221         int want_reply;
1222         int r, success = 0, allocated_listen_port = 0;
1223         struct sshbuf *resp = NULL;
1224
1225         rtype = packet_get_string(NULL);
1226         want_reply = packet_get_char();
1227         debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1228
1229         /* -R style forwarding */
1230         if (strcmp(rtype, "tcpip-forward") == 0) {
1231                 struct passwd *pw;
1232                 struct Forward fwd;
1233
1234                 pw = the_authctxt->pw;
1235                 if (pw == NULL || !the_authctxt->valid)
1236                         fatal("server_input_global_request: no/invalid user");
1237                 memset(&fwd, 0, sizeof(fwd));
1238                 fwd.listen_host = packet_get_string(NULL);
1239                 fwd.listen_port = (u_short)packet_get_int();
1240                 debug("server_input_global_request: tcpip-forward listen %s port %d",
1241                     fwd.listen_host, fwd.listen_port);
1242
1243                 /* check permissions */
1244                 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
1245                     no_port_forwarding_flag ||
1246                     (!want_reply && fwd.listen_port == 0) ||
1247                     (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
1248                     pw->pw_uid != 0)) {
1249                         success = 0;
1250                         packet_send_debug("Server has disabled port forwarding.");
1251                 } else {
1252                         /* Start listening on the port */
1253                         success = channel_setup_remote_fwd_listener(&fwd,
1254                             &allocated_listen_port, &options.fwd_opts);
1255                 }
1256                 free(fwd.listen_host);
1257                 if ((resp = sshbuf_new()) == NULL)
1258                         fatal("%s: sshbuf_new", __func__);
1259                 if (allocated_listen_port != 0 &&
1260                     (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
1261                         fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
1262         } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
1263                 struct Forward fwd;
1264
1265                 memset(&fwd, 0, sizeof(fwd));
1266                 fwd.listen_host = packet_get_string(NULL);
1267                 fwd.listen_port = (u_short)packet_get_int();
1268                 debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
1269                     fwd.listen_host, fwd.listen_port);
1270
1271                 success = channel_cancel_rport_listener(&fwd);
1272                 free(fwd.listen_host);
1273         } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
1274                 struct Forward fwd;
1275
1276                 memset(&fwd, 0, sizeof(fwd));
1277                 fwd.listen_path = packet_get_string(NULL);
1278                 debug("server_input_global_request: streamlocal-forward listen path %s",
1279                     fwd.listen_path);
1280
1281                 /* check permissions */
1282                 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
1283                     || no_port_forwarding_flag) {
1284                         success = 0;
1285                         packet_send_debug("Server has disabled port forwarding.");
1286                 } else {
1287                         /* Start listening on the socket */
1288                         success = channel_setup_remote_fwd_listener(
1289                             &fwd, NULL, &options.fwd_opts);
1290                 }
1291                 free(fwd.listen_path);
1292         } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
1293                 struct Forward fwd;
1294
1295                 memset(&fwd, 0, sizeof(fwd));
1296                 fwd.listen_path = packet_get_string(NULL);
1297                 debug("%s: cancel-streamlocal-forward path %s", __func__,
1298                     fwd.listen_path);
1299
1300                 success = channel_cancel_rport_listener(&fwd);
1301                 free(fwd.listen_path);
1302         } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
1303                 no_more_sessions = 1;
1304                 success = 1;
1305         } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
1306                 success = server_input_hostkeys_prove(&resp);
1307         }
1308         if (want_reply) {
1309                 packet_start(success ?
1310                     SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1311                 if (success && resp != NULL)
1312                         ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
1313                             sshbuf_len(resp));
1314                 packet_send();
1315                 packet_write_wait();
1316         }
1317         free(rtype);
1318         sshbuf_free(resp);
1319         return 0;
1320 }
1321
1322 static int
1323 server_input_channel_req(int type, u_int32_t seq, void *ctxt)
1324 {
1325         Channel *c;
1326         int id, reply, success = 0;
1327         char *rtype;
1328
1329         id = packet_get_int();
1330         rtype = packet_get_string(NULL);
1331         reply = packet_get_char();
1332
1333         debug("server_input_channel_req: channel %d request %s reply %d",
1334             id, rtype, reply);
1335
1336         if ((c = channel_lookup(id)) == NULL)
1337                 packet_disconnect("server_input_channel_req: "
1338                     "unknown channel %d", id);
1339         if (!strcmp(rtype, "eow@openssh.com")) {
1340                 packet_check_eom();
1341                 chan_rcvd_eow(c);
1342         } else if ((c->type == SSH_CHANNEL_LARVAL ||
1343             c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
1344                 success = session_input_channel_req(c, rtype);
1345         if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
1346                 packet_start(success ?
1347                     SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1348                 packet_put_int(c->remote_id);
1349                 packet_send();
1350         }
1351         free(rtype);
1352         return 0;
1353 }
1354
1355 static void
1356 server_init_dispatch_20(void)
1357 {
1358         debug("server_init_dispatch_20");
1359         dispatch_init(&dispatch_protocol_error);
1360         dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1361         dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1362         dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1363         dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1364         dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
1365         dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1366         dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1367         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
1368         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1369         dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
1370         /* client_alive */
1371         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
1372         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
1373         dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
1374         dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
1375         /* rekeying */
1376         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1377 }
1378 static void
1379 server_init_dispatch_13(void)
1380 {
1381         debug("server_init_dispatch_13");
1382         dispatch_init(NULL);
1383         dispatch_set(SSH_CMSG_EOF, &server_input_eof);
1384         dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
1385         dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
1386         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1387         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1388         dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1389         dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1390         dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1391         dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1392 }
1393 static void
1394 server_init_dispatch_15(void)
1395 {
1396         server_init_dispatch_13();
1397         debug("server_init_dispatch_15");
1398         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1399         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
1400 }
1401 static void
1402 server_init_dispatch(void)
1403 {
1404         if (compat20)
1405                 server_init_dispatch_20();
1406         else if (compat13)
1407                 server_init_dispatch_13();
1408         else
1409                 server_init_dispatch_15();
1410 }