nchan.c

   1 /* $OpenBSD: nchan.c,v 1.62 2008/11/07 18:50:18 stevesk Exp $ */
   2 /*
   3  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30
  31 #include <errno.h>
  32 #include <string.h>
  33 #include <stdarg.h>
  34
  35 #include "openbsd-compat/sys-queue.h"
  36 #include "ssh1.h"
  37 #include "ssh2.h"
  38 #include "buffer.h"
  39 #include "packet.h"
  40 #include "channels.h"
  41 #include "compat.h"
  42 #include "log.h"
  43
  44 /*
  45  * SSH Protocol 1.5 aka New Channel Protocol
  46  * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored.
  47  * Written by Markus Friedl in October 1999
  48  *
  49  * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the
  50  * tear down of channels:
  51  *
  52  * 1.3: strict request-ack-protocol:
  53  *      CLOSE   ->
  54  *              <-  CLOSE_CONFIRM
  55  *
  56  * 1.5: uses variations of:
  57  *      IEOF    ->
  58  *              <-  OCLOSE
  59  *              <-  IEOF
  60  *      OCLOSE  ->
  61  *      i.e. both sides have to close the channel
  62  *
  63  * 2.0: the EOF messages are optional
  64  *
  65  * See the debugging output from 'ssh -v' and 'sshd -d' of
  66  * ssh-1.2.27 as an example.
  67  *
  68  */
  69
  70 /* functions manipulating channel states */
  71 /*
  72  * EVENTS update channel input/output states execute ACTIONS
  73  */
  74 /*
  75  * ACTIONS: should never update the channel states
  76  */
  77 static void     chan_send_ieof1(Channel *);
  78 static void     chan_send_oclose1(Channel *);
  79 static void     chan_send_close2(Channel *);
  80 static void     chan_send_eof2(Channel *);
  81 static void     chan_send_eow2(Channel *);
  82
  83 /* helper */
  84 static void     chan_shutdown_write(Channel *);
  85 static void     chan_shutdown_read(Channel *);
  86
  87 static char *ostates[] = { "open", "drain", "wait_ieof", "closed" };
  88 static char *istates[] = { "open", "drain", "wait_oclose", "closed" };
  89
  90 static void
  91 chan_set_istate(Channel *c, u_int next)
  92 {
  93         if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED)
  94                 fatal("chan_set_istate: bad state %d -> %d", c->istate, next);
  95         debug2("channel %d: input %s -> %s", c->self, istates[c->istate],
  96             istates[next]);
  97         c->istate = next;
  98 }
  99 static void
 100 chan_set_ostate(Channel *c, u_int next)
 101 {
 102         if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED)
 103                 fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next);
 104         debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate],
 105             ostates[next]);
 106         c->ostate = next;
 107 }
 108
 109 /*
 110  * SSH1 specific implementation of event functions
 111  */
 112
 113 static void
 114 chan_rcvd_oclose1(Channel *c)
 115 {
 116         debug2("channel %d: rcvd oclose", c->self);
 117         switch (c->istate) {
 118         case CHAN_INPUT_WAIT_OCLOSE:
 119                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 120                 break;
 121         case CHAN_INPUT_OPEN:
 122                 chan_shutdown_read(c);
 123                 chan_send_ieof1(c);
 124                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 125                 break;
 126         case CHAN_INPUT_WAIT_DRAIN:
 127                 /* both local read_failed and remote write_failed  */
 128                 chan_send_ieof1(c);
 129                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 130                 break;
 131         default:
 132                 error("channel %d: protocol error: rcvd_oclose for istate %d",
 133                     c->self, c->istate);
 134                 return;
 135         }
 136 }
 137 void
 138 chan_read_failed(Channel *c)
 139 {
 140         debug2("channel %d: read failed", c->self);
 141         switch (c->istate) {
 142         case CHAN_INPUT_OPEN:
 143                 chan_shutdown_read(c);
 144                 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN);
 145                 break;
 146         default:
 147                 error("channel %d: chan_read_failed for istate %d",
 148                     c->self, c->istate);
 149                 break;
 150         }
 151 }
 152 void
 153 chan_ibuf_empty(Channel *c)
 154 {
 155         debug2("channel %d: ibuf empty", c->self);
 156         if (buffer_len(&c->input)) {
 157                 error("channel %d: chan_ibuf_empty for non empty buffer",
 158                     c->self);
 159                 return;
 160         }
 161         switch (c->istate) {
 162         case CHAN_INPUT_WAIT_DRAIN:
 163                 if (compat20) {
 164                         if (!(c->flags & CHAN_CLOSE_SENT))
 165                                 chan_send_eof2(c);
 166                         chan_set_istate(c, CHAN_INPUT_CLOSED);
 167                 } else {
 168                         chan_send_ieof1(c);
 169                         chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE);
 170                 }
 171                 break;
 172         default:
 173                 error("channel %d: chan_ibuf_empty for istate %d",
 174                     c->self, c->istate);
 175                 break;
 176         }
 177 }
 178 static void
 179 chan_rcvd_ieof1(Channel *c)
 180 {
 181         debug2("channel %d: rcvd ieof", c->self);
 182         switch (c->ostate) {
 183         case CHAN_OUTPUT_OPEN:
 184                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 185                 break;
 186         case CHAN_OUTPUT_WAIT_IEOF:
 187                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 188                 break;
 189         default:
 190                 error("channel %d: protocol error: rcvd_ieof for ostate %d",
 191                     c->self, c->ostate);
 192                 break;
 193         }
 194 }
 195 static void
 196 chan_write_failed1(Channel *c)
 197 {
 198         debug2("channel %d: write failed", c->self);
 199         switch (c->ostate) {
 200         case CHAN_OUTPUT_OPEN:
 201                 chan_shutdown_write(c);
 202                 chan_send_oclose1(c);
 203                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF);
 204                 break;
 205         case CHAN_OUTPUT_WAIT_DRAIN:
 206                 chan_shutdown_write(c);
 207                 chan_send_oclose1(c);
 208                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 209                 break;
 210         default:
 211                 error("channel %d: chan_write_failed for ostate %d",
 212                     c->self, c->ostate);
 213                 break;
 214         }
 215 }
 216 void
 217 chan_obuf_empty(Channel *c)
 218 {
 219         debug2("channel %d: obuf empty", c->self);
 220         if (buffer_len(&c->output)) {
 221                 error("channel %d: chan_obuf_empty for non empty buffer",
 222                     c->self);
 223                 return;
 224         }
 225         switch (c->ostate) {
 226         case CHAN_OUTPUT_WAIT_DRAIN:
 227                 chan_shutdown_write(c);
 228                 if (!compat20)
 229                         chan_send_oclose1(c);
 230                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 231                 break;
 232         default:
 233                 error("channel %d: internal error: obuf_empty for ostate %d",
 234                     c->self, c->ostate);
 235                 break;
 236         }
 237 }
 238 static void
 239 chan_send_ieof1(Channel *c)
 240 {
 241         debug2("channel %d: send ieof", c->self);
 242         switch (c->istate) {
 243         case CHAN_INPUT_OPEN:
 244         case CHAN_INPUT_WAIT_DRAIN:
 245                 packet_start(SSH_MSG_CHANNEL_INPUT_EOF);
 246                 packet_put_int(c->remote_id);
 247                 packet_send();
 248                 break;
 249         default:
 250                 error("channel %d: cannot send ieof for istate %d",
 251                     c->self, c->istate);
 252                 break;
 253         }
 254 }
 255 static void
 256 chan_send_oclose1(Channel *c)
 257 {
 258         debug2("channel %d: send oclose", c->self);
 259         switch (c->ostate) {
 260         case CHAN_OUTPUT_OPEN:
 261         case CHAN_OUTPUT_WAIT_DRAIN:
 262                 buffer_clear(&c->output);
 263                 packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE);
 264                 packet_put_int(c->remote_id);
 265                 packet_send();
 266                 break;
 267         default:
 268                 error("channel %d: cannot send oclose for ostate %d",
 269                     c->self, c->ostate);
 270                 break;
 271         }
 272 }
 273
 274 /*
 275  * the same for SSH2
 276  */
 277 static void
 278 chan_rcvd_close2(Channel *c)
 279 {
 280         debug2("channel %d: rcvd close", c->self);
 281         if (c->flags & CHAN_CLOSE_RCVD)
 282                 error("channel %d: protocol error: close rcvd twice", c->self);
 283         c->flags |= CHAN_CLOSE_RCVD;
 284         if (c->type == SSH_CHANNEL_LARVAL) {
 285                 /* tear down larval channels immediately */
 286                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 287                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 288                 return;
 289         }
 290         switch (c->ostate) {
 291         case CHAN_OUTPUT_OPEN:
 292                 /*
 293                  * wait until a data from the channel is consumed if a CLOSE
 294                  * is received
 295                  */
 296                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 297                 break;
 298         }
 299         switch (c->istate) {
 300         case CHAN_INPUT_OPEN:
 301                 chan_shutdown_read(c);
 302                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 303                 break;
 304         case CHAN_INPUT_WAIT_DRAIN:
 305                 chan_send_eof2(c);
 306                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 307                 break;
 308         }
 309 }
 310 void
 311 chan_rcvd_eow(Channel *c)
 312 {
 313         debug2("channel %d: rcvd eow", c->self);
 314         switch (c->istate) {
 315         case CHAN_INPUT_OPEN:
 316                 chan_shutdown_read(c);
 317                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 318                 break;
 319         }
 320 }
 321 static void
 322 chan_rcvd_eof2(Channel *c)
 323 {
 324         debug2("channel %d: rcvd eof", c->self);
 325         c->flags |= CHAN_EOF_RCVD;
 326         if (c->ostate == CHAN_OUTPUT_OPEN)
 327                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 328 }
 329 static void
 330 chan_write_failed2(Channel *c)
 331 {
 332         debug2("channel %d: write failed", c->self);
 333         switch (c->ostate) {
 334         case CHAN_OUTPUT_OPEN:
 335         case CHAN_OUTPUT_WAIT_DRAIN:
 336                 chan_shutdown_write(c);
 337                 if (strcmp(c->ctype, "session") == 0)
 338                         chan_send_eow2(c);
 339                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 340                 break;
 341         default:
 342                 error("channel %d: chan_write_failed for ostate %d",
 343                     c->self, c->ostate);
 344                 break;
 345         }
 346 }
 347 static void
 348 chan_send_eof2(Channel *c)
 349 {
 350         debug2("channel %d: send eof", c->self);
 351         switch (c->istate) {
 352         case CHAN_INPUT_WAIT_DRAIN:
 353                 packet_start(SSH2_MSG_CHANNEL_EOF);
 354                 packet_put_int(c->remote_id);
 355                 packet_send();
 356                 c->flags |= CHAN_EOF_SENT;
 357                 break;
 358         default:
 359                 error("channel %d: cannot send eof for istate %d",
 360                     c->self, c->istate);
 361                 break;
 362         }
 363 }
 364 static void
 365 chan_send_close2(Channel *c)
 366 {
 367         debug2("channel %d: send close", c->self);
 368         if (c->ostate != CHAN_OUTPUT_CLOSED ||
 369             c->istate != CHAN_INPUT_CLOSED) {
 370                 error("channel %d: cannot send close for istate/ostate %d/%d",
 371                     c->self, c->istate, c->ostate);
 372         } else if (c->flags & CHAN_CLOSE_SENT) {
 373                 error("channel %d: already sent close", c->self);
 374         } else {
 375                 packet_start(SSH2_MSG_CHANNEL_CLOSE);
 376                 packet_put_int(c->remote_id);
 377                 packet_send();
 378                 c->flags |= CHAN_CLOSE_SENT;
 379         }
 380 }
 381 static void
 382 chan_send_eow2(Channel *c)
 383 {
 384         debug2("channel %d: send eow", c->self);
 385         if (c->ostate == CHAN_OUTPUT_CLOSED) {
 386                 error("channel %d: must not sent eow on closed output",
 387                     c->self);
 388                 return;
 389         }
 390         if (!(datafellows & SSH_NEW_OPENSSH))
 391                 return;
 392         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 393         packet_put_int(c->remote_id);
 394         packet_put_cstring("eow@openssh.com");
 395         packet_put_char(0);
 396         packet_send();
 397 }
 398
 399 /* shared */
 400
 401 void
 402 chan_rcvd_ieof(Channel *c)
 403 {
 404         if (compat20)
 405                 chan_rcvd_eof2(c);
 406         else
 407                 chan_rcvd_ieof1(c);
 408         if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
 409             buffer_len(&c->output) == 0 &&
 410             !CHANNEL_EFD_OUTPUT_ACTIVE(c))
 411                 chan_obuf_empty(c);
 412 }
 413 void
 414 chan_rcvd_oclose(Channel *c)
 415 {
 416         if (compat20)
 417                 chan_rcvd_close2(c);
 418         else
 419                 chan_rcvd_oclose1(c);
 420 }
 421 void
 422 chan_write_failed(Channel *c)
 423 {
 424         if (compat20)
 425                 chan_write_failed2(c);
 426         else
 427                 chan_write_failed1(c);
 428 }
 429
 430 void
 431 chan_mark_dead(Channel *c)
 432 {
 433         c->type = SSH_CHANNEL_ZOMBIE;
 434 }
 435
 436 int
 437 chan_is_dead(Channel *c, int do_send)
 438 {
 439         if (c->type == SSH_CHANNEL_ZOMBIE) {
 440                 debug2("channel %d: zombie", c->self);
 441                 return 1;
 442         }
 443         if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED)
 444                 return 0;
 445         if (!compat20) {
 446                 debug2("channel %d: is dead", c->self);
 447                 return 1;
 448         }
 449         if ((datafellows & SSH_BUG_EXTEOF) &&
 450             c->extended_usage == CHAN_EXTENDED_WRITE &&
 451             c->efd != -1 &&
 452             buffer_len(&c->extended) > 0) {
 453                 debug2("channel %d: active efd: %d len %d",
 454                     c->self, c->efd, buffer_len(&c->extended));
 455                 return 0;
 456         }
 457         if (!(c->flags & CHAN_CLOSE_SENT)) {
 458                 if (do_send) {
 459                         chan_send_close2(c);
 460                 } else {
 461                         /* channel would be dead if we sent a close */
 462                         if (c->flags & CHAN_CLOSE_RCVD) {
 463                                 debug2("channel %d: almost dead",
 464                                     c->self);
 465                                 return 1;
 466                         }
 467                 }
 468         }
 469         if ((c->flags & CHAN_CLOSE_SENT) &&
 470             (c->flags & CHAN_CLOSE_RCVD)) {
 471                 debug2("channel %d: is dead", c->self);
 472                 return 1;
 473         }
 474         return 0;
 475 }
 476
 477 /* helper */
 478 static void
 479 chan_shutdown_write(Channel *c)
 480 {
 481         buffer_clear(&c->output);
 482         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 483                 return;
 484         /* shutdown failure is allowed if write failed already */
 485         debug2("channel %d: close_write", c->self);
 486         if (c->sock != -1) {
 487                 if (shutdown(c->sock, SHUT_WR) < 0)
 488                         debug2("channel %d: chan_shutdown_write: "
 489                             "shutdown() failed for fd %d: %.100s",
 490                             c->self, c->sock, strerror(errno));
 491         } else {
 492                 if (channel_close_fd(&c->wfd) < 0)
 493                         logit("channel %d: chan_shutdown_write: "
 494                             "close() failed for fd %d: %.100s",
 495                             c->self, c->wfd, strerror(errno));
 496         }
 497 }
 498 static void
 499 chan_shutdown_read(Channel *c)
 500 {
 501         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 502                 return;
 503         debug2("channel %d: close_read", c->self);
 504         if (c->sock != -1) {
 505                 /*
 506                  * shutdown(sock, SHUT_READ) may return ENOTCONN if the
 507                  * write side has been closed already. (bug on Linux)
 508                  * HP-UX may return ENOTCONN also.
 509                  */
 510                 if (shutdown(c->sock, SHUT_RD) < 0
 511                     && errno != ENOTCONN)
 512                         error("channel %d: chan_shutdown_read: "
 513                             "shutdown() failed for fd %d [i%d o%d]: %.100s",
 514                             c->self, c->sock, c->istate, c->ostate,
 515                             strerror(errno));
 516         } else {
 517                 if (channel_close_fd(&c->rfd) < 0)
 518                         logit("channel %d: chan_shutdown_read: "
 519                             "close() failed for fd %d: %.100s",
 520                             c->self, c->rfd, strerror(errno));
 521         }
 522 }