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