1 /* $OpenBSD: nchan.c,v 1.57 2006/08/03 03:34:42 deraadt 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 "ssh1.h" 36 #include "ssh2.h" 37 #include "buffer.h" 38 #include "packet.h" 39 #include "channels.h" 40 #include "compat.h" 41 #include "log.h" 42 43 /* 44 * SSH Protocol 1.5 aka New Channel Protocol 45 * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. 46 * Written by Markus Friedl in October 1999 47 * 48 * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the 49 * tear down of channels: 50 * 51 * 1.3: strict request-ack-protocol: 52 * CLOSE -> 53 * <- CLOSE_CONFIRM 54 * 55 * 1.5: uses variations of: 56 * IEOF -> 57 * <- OCLOSE 58 * <- IEOF 59 * OCLOSE -> 60 * i.e. both sides have to close the channel 61 * 62 * 2.0: the EOF messages are optional 63 * 64 * See the debugging output from 'ssh -v' and 'sshd -d' of 65 * ssh-1.2.27 as an example. 66 * 67 */ 68 69 /* functions manipulating channel states */ 70 /* 71 * EVENTS update channel input/output states execute ACTIONS 72 */ 73 /* 74 * ACTIONS: should never update the channel states 75 */ 76 static void chan_send_ieof1(Channel *); 77 static void chan_send_oclose1(Channel *); 78 static void chan_send_close2(Channel *); 79 static void chan_send_eof2(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 static void 309 chan_rcvd_eof2(Channel *c) 310 { 311 debug2("channel %d: rcvd eof", c->self); 312 c->flags |= CHAN_EOF_RCVD; 313 if (c->ostate == CHAN_OUTPUT_OPEN) 314 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 315 } 316 static void 317 chan_write_failed2(Channel *c) 318 { 319 debug2("channel %d: write failed", c->self); 320 switch (c->ostate) { 321 case CHAN_OUTPUT_OPEN: 322 case CHAN_OUTPUT_WAIT_DRAIN: 323 chan_shutdown_write(c); 324 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 325 break; 326 default: 327 error("channel %d: chan_write_failed for ostate %d", 328 c->self, c->ostate); 329 break; 330 } 331 } 332 static void 333 chan_send_eof2(Channel *c) 334 { 335 debug2("channel %d: send eof", c->self); 336 switch (c->istate) { 337 case CHAN_INPUT_WAIT_DRAIN: 338 packet_start(SSH2_MSG_CHANNEL_EOF); 339 packet_put_int(c->remote_id); 340 packet_send(); 341 c->flags |= CHAN_EOF_SENT; 342 break; 343 default: 344 error("channel %d: cannot send eof for istate %d", 345 c->self, c->istate); 346 break; 347 } 348 } 349 static void 350 chan_send_close2(Channel *c) 351 { 352 debug2("channel %d: send close", c->self); 353 if (c->ostate != CHAN_OUTPUT_CLOSED || 354 c->istate != CHAN_INPUT_CLOSED) { 355 error("channel %d: cannot send close for istate/ostate %d/%d", 356 c->self, c->istate, c->ostate); 357 } else if (c->flags & CHAN_CLOSE_SENT) { 358 error("channel %d: already sent close", c->self); 359 } else { 360 packet_start(SSH2_MSG_CHANNEL_CLOSE); 361 packet_put_int(c->remote_id); 362 packet_send(); 363 c->flags |= CHAN_CLOSE_SENT; 364 } 365 } 366 367 /* shared */ 368 369 void 370 chan_rcvd_ieof(Channel *c) 371 { 372 if (compat20) 373 chan_rcvd_eof2(c); 374 else 375 chan_rcvd_ieof1(c); 376 if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && 377 buffer_len(&c->output) == 0 && 378 !CHANNEL_EFD_OUTPUT_ACTIVE(c)) 379 chan_obuf_empty(c); 380 } 381 void 382 chan_rcvd_oclose(Channel *c) 383 { 384 if (compat20) 385 chan_rcvd_close2(c); 386 else 387 chan_rcvd_oclose1(c); 388 } 389 void 390 chan_write_failed(Channel *c) 391 { 392 if (compat20) 393 chan_write_failed2(c); 394 else 395 chan_write_failed1(c); 396 } 397 398 void 399 chan_mark_dead(Channel *c) 400 { 401 c->type = SSH_CHANNEL_ZOMBIE; 402 } 403 404 int 405 chan_is_dead(Channel *c, int do_send) 406 { 407 if (c->type == SSH_CHANNEL_ZOMBIE) { 408 debug2("channel %d: zombie", c->self); 409 return 1; 410 } 411 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) 412 return 0; 413 if (!compat20) { 414 debug2("channel %d: is dead", c->self); 415 return 1; 416 } 417 if ((datafellows & SSH_BUG_EXTEOF) && 418 c->extended_usage == CHAN_EXTENDED_WRITE && 419 c->efd != -1 && 420 buffer_len(&c->extended) > 0) { 421 debug2("channel %d: active efd: %d len %d", 422 c->self, c->efd, buffer_len(&c->extended)); 423 return 0; 424 } 425 if (!(c->flags & CHAN_CLOSE_SENT)) { 426 if (do_send) { 427 chan_send_close2(c); 428 } else { 429 /* channel would be dead if we sent a close */ 430 if (c->flags & CHAN_CLOSE_RCVD) { 431 debug2("channel %d: almost dead", 432 c->self); 433 return 1; 434 } 435 } 436 } 437 if ((c->flags & CHAN_CLOSE_SENT) && 438 (c->flags & CHAN_CLOSE_RCVD)) { 439 debug2("channel %d: is dead", c->self); 440 return 1; 441 } 442 return 0; 443 } 444 445 /* helper */ 446 static void 447 chan_shutdown_write(Channel *c) 448 { 449 buffer_clear(&c->output); 450 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 451 return; 452 /* shutdown failure is allowed if write failed already */ 453 debug2("channel %d: close_write", c->self); 454 if (c->sock != -1) { 455 if (shutdown(c->sock, SHUT_WR) < 0) 456 debug2("channel %d: chan_shutdown_write: " 457 "shutdown() failed for fd%d: %.100s", 458 c->self, c->sock, strerror(errno)); 459 } else { 460 if (channel_close_fd(&c->wfd) < 0) 461 logit("channel %d: chan_shutdown_write: " 462 "close() failed for fd%d: %.100s", 463 c->self, c->wfd, strerror(errno)); 464 } 465 } 466 static void 467 chan_shutdown_read(Channel *c) 468 { 469 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 470 return; 471 debug2("channel %d: close_read", c->self); 472 if (c->sock != -1) { 473 /* 474 * shutdown(sock, SHUT_READ) may return ENOTCONN if the 475 * write side has been closed already. (bug on Linux) 476 * HP-UX may return ENOTCONN also. 477 */ 478 if (shutdown(c->sock, SHUT_RD) < 0 479 && errno != ENOTCONN) 480 error("channel %d: chan_shutdown_read: " 481 "shutdown() failed for fd%d [i%d o%d]: %.100s", 482 c->self, c->sock, c->istate, c->ostate, 483 strerror(errno)); 484 } else { 485 if (channel_close_fd(&c->rfd) < 0) 486 logit("channel %d: chan_shutdown_read: " 487 "close() failed for fd%d: %.100s", 488 c->self, c->rfd, strerror(errno)); 489 } 490 } 491