nchan.c

   1 /* $OpenBSD: nchan.c,v 1.63 2010/01/26 01:28:35 djm 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|CHAN_LOCAL)))
 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_LOCAL)) {
 282                 if (c->flags & CHAN_CLOSE_RCVD)
 283                         error("channel %d: protocol error: close rcvd twice",
 284                             c->self);
 285                 c->flags |= CHAN_CLOSE_RCVD;
 286         }
 287         if (c->type == SSH_CHANNEL_LARVAL) {
 288                 /* tear down larval channels immediately */
 289                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 290                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 291                 return;
 292         }
 293         switch (c->ostate) {
 294         case CHAN_OUTPUT_OPEN:
 295                 /*
 296                  * wait until a data from the channel is consumed if a CLOSE
 297                  * is received
 298                  */
 299                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 300                 break;
 301         }
 302         switch (c->istate) {
 303         case CHAN_INPUT_OPEN:
 304                 chan_shutdown_read(c);
 305                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 306                 break;
 307         case CHAN_INPUT_WAIT_DRAIN:
 308                 if (!(c->flags & CHAN_LOCAL))
 309                         chan_send_eof2(c);
 310                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 311                 break;
 312         }
 313 }
 314
 315 void
 316 chan_rcvd_eow(Channel *c)
 317 {
 318         debug2("channel %d: rcvd eow", c->self);
 319         switch (c->istate) {
 320         case CHAN_INPUT_OPEN:
 321                 chan_shutdown_read(c);
 322                 chan_set_istate(c, CHAN_INPUT_CLOSED);
 323                 break;
 324         }
 325 }
 326 static void
 327 chan_rcvd_eof2(Channel *c)
 328 {
 329         debug2("channel %d: rcvd eof", c->self);
 330         c->flags |= CHAN_EOF_RCVD;
 331         if (c->ostate == CHAN_OUTPUT_OPEN)
 332                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 333 }
 334 static void
 335 chan_write_failed2(Channel *c)
 336 {
 337         debug2("channel %d: write failed", c->self);
 338         switch (c->ostate) {
 339         case CHAN_OUTPUT_OPEN:
 340         case CHAN_OUTPUT_WAIT_DRAIN:
 341                 chan_shutdown_write(c);
 342                 if (strcmp(c->ctype, "session") == 0)
 343                         chan_send_eow2(c);
 344                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 345                 break;
 346         default:
 347                 error("channel %d: chan_write_failed for ostate %d",
 348                     c->self, c->ostate);
 349                 break;
 350         }
 351 }
 352 static void
 353 chan_send_eof2(Channel *c)
 354 {
 355         debug2("channel %d: send eof", c->self);
 356         switch (c->istate) {
 357         case CHAN_INPUT_WAIT_DRAIN:
 358                 packet_start(SSH2_MSG_CHANNEL_EOF);
 359                 packet_put_int(c->remote_id);
 360                 packet_send();
 361                 c->flags |= CHAN_EOF_SENT;
 362                 break;
 363         default:
 364                 error("channel %d: cannot send eof for istate %d",
 365                     c->self, c->istate);
 366                 break;
 367         }
 368 }
 369 static void
 370 chan_send_close2(Channel *c)
 371 {
 372         debug2("channel %d: send close", c->self);
 373         if (c->ostate != CHAN_OUTPUT_CLOSED ||
 374             c->istate != CHAN_INPUT_CLOSED) {
 375                 error("channel %d: cannot send close for istate/ostate %d/%d",
 376                     c->self, c->istate, c->ostate);
 377         } else if (c->flags & CHAN_CLOSE_SENT) {
 378                 error("channel %d: already sent close", c->self);
 379         } else {
 380                 packet_start(SSH2_MSG_CHANNEL_CLOSE);
 381                 packet_put_int(c->remote_id);
 382                 packet_send();
 383                 c->flags |= CHAN_CLOSE_SENT;
 384         }
 385 }
 386 static void
 387 chan_send_eow2(Channel *c)
 388 {
 389         debug2("channel %d: send eow", c->self);
 390         if (c->ostate == CHAN_OUTPUT_CLOSED) {
 391                 error("channel %d: must not sent eow on closed output",
 392                     c->self);
 393                 return;
 394         }
 395         if (!(datafellows & SSH_NEW_OPENSSH))
 396                 return;
 397         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 398         packet_put_int(c->remote_id);
 399         packet_put_cstring("eow@openssh.com");
 400         packet_put_char(0);
 401         packet_send();
 402 }
 403
 404 /* shared */
 405
 406 void
 407 chan_rcvd_ieof(Channel *c)
 408 {
 409         if (compat20)
 410                 chan_rcvd_eof2(c);
 411         else
 412                 chan_rcvd_ieof1(c);
 413         if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
 414             buffer_len(&c->output) == 0 &&
 415             !CHANNEL_EFD_OUTPUT_ACTIVE(c))
 416                 chan_obuf_empty(c);
 417 }
 418 void
 419 chan_rcvd_oclose(Channel *c)
 420 {
 421         if (compat20)
 422                 chan_rcvd_close2(c);
 423         else
 424                 chan_rcvd_oclose1(c);
 425 }
 426 void
 427 chan_write_failed(Channel *c)
 428 {
 429         if (compat20)
 430                 chan_write_failed2(c);
 431         else
 432                 chan_write_failed1(c);
 433 }
 434
 435 void
 436 chan_mark_dead(Channel *c)
 437 {
 438         c->type = SSH_CHANNEL_ZOMBIE;
 439 }
 440
 441 int
 442 chan_is_dead(Channel *c, int do_send)
 443 {
 444         if (c->type == SSH_CHANNEL_ZOMBIE) {
 445                 debug2("channel %d: zombie", c->self);
 446                 return 1;
 447         }
 448         if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED)
 449                 return 0;
 450         if (!compat20) {
 451                 debug2("channel %d: is dead", c->self);
 452                 return 1;
 453         }
 454         if ((datafellows & SSH_BUG_EXTEOF) &&
 455             c->extended_usage == CHAN_EXTENDED_WRITE &&
 456             c->efd != -1 &&
 457             buffer_len(&c->extended) > 0) {
 458                 debug2("channel %d: active efd: %d len %d",
 459                     c->self, c->efd, buffer_len(&c->extended));
 460                 return 0;
 461         }
 462         if (c->flags & CHAN_LOCAL) {
 463                 debug2("channel %d: is dead (local)", c->self);
 464                 return 1;
 465         }
 466         if (!(c->flags & CHAN_CLOSE_SENT)) {
 467                 if (do_send) {
 468                         chan_send_close2(c);
 469                 } else {
 470                         /* channel would be dead if we sent a close */
 471                         if (c->flags & CHAN_CLOSE_RCVD) {
 472                                 debug2("channel %d: almost dead",
 473                                     c->self);
 474                                 return 1;
 475                         }
 476                 }
 477         }
 478         if ((c->flags & CHAN_CLOSE_SENT) &&
 479             (c->flags & CHAN_CLOSE_RCVD)) {
 480                 debug2("channel %d: is dead", c->self);
 481                 return 1;
 482         }
 483         return 0;
 484 }
 485
 486 /* helper */
 487 static void
 488 chan_shutdown_write(Channel *c)
 489 {
 490         buffer_clear(&c->output);
 491         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 492                 return;
 493         /* shutdown failure is allowed if write failed already */
 494         debug2("channel %d: close_write", c->self);
 495         if (c->sock != -1) {
 496                 if (shutdown(c->sock, SHUT_WR) < 0)
 497                         debug2("channel %d: chan_shutdown_write: "
 498                             "shutdown() failed for fd %d: %.100s",
 499                             c->self, c->sock, strerror(errno));
 500         } else {
 501                 if (channel_close_fd(&c->wfd) < 0)
 502                         logit("channel %d: chan_shutdown_write: "
 503                             "close() failed for fd %d: %.100s",
 504                             c->self, c->wfd, strerror(errno));
 505         }
 506 }
 507 static void
 508 chan_shutdown_read(Channel *c)
 509 {
 510         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 511                 return;
 512         debug2("channel %d: close_read", c->self);
 513         if (c->sock != -1) {
 514                 /*
 515                  * shutdown(sock, SHUT_READ) may return ENOTCONN if the
 516                  * write side has been closed already. (bug on Linux)
 517                  * HP-UX may return ENOTCONN also.
 518                  */
 519                 if (shutdown(c->sock, SHUT_RD) < 0
 520                     && errno != ENOTCONN)
 521                         error("channel %d: chan_shutdown_read: "
 522                             "shutdown() failed for fd %d [i%d o%d]: %.100s",
 523                             c->self, c->sock, c->istate, c->ostate,
 524                             strerror(errno));
 525         } else {
 526                 if (channel_close_fd(&c->rfd) < 0)
 527                         logit("channel %d: chan_shutdown_read: "
 528                             "close() failed for fd %d: %.100s",
 529                             c->self, c->rfd, strerror(errno));
 530         }
 531 }