1 /* $OpenBSD: nchan.c,v 1.70 2019/06/28 13:35:04 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 "openbsd-compat/sys-queue.h" 36 #include "ssh2.h" 37 #include "sshbuf.h" 38 #include "ssherr.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_eof2(struct ssh *, Channel *); 78 static void chan_send_eow2(struct ssh *, Channel *); 79 80 /* helper */ 81 static void chan_shutdown_write(struct ssh *, Channel *); 82 static void chan_shutdown_read(struct ssh *, Channel *); 83 static void chan_shutdown_extended_read(struct ssh *, Channel *); 84 85 static const char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; 86 static const 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 98 static void 99 chan_set_ostate(Channel *c, u_int next) 100 { 101 if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) 102 fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); 103 debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate], 104 ostates[next]); 105 c->ostate = next; 106 } 107 108 void 109 chan_read_failed(struct ssh *ssh, Channel *c) 110 { 111 debug2("channel %d: read failed", c->self); 112 switch (c->istate) { 113 case CHAN_INPUT_OPEN: 114 chan_shutdown_read(ssh, c); 115 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); 116 break; 117 default: 118 error("channel %d: chan_read_failed for istate %d", 119 c->self, c->istate); 120 break; 121 } 122 } 123 124 void 125 chan_ibuf_empty(struct ssh *ssh, Channel *c) 126 { 127 debug2("channel %d: ibuf empty", c->self); 128 if (sshbuf_len(c->input)) { 129 error("channel %d: chan_ibuf_empty for non empty buffer", 130 c->self); 131 return; 132 } 133 switch (c->istate) { 134 case CHAN_INPUT_WAIT_DRAIN: 135 if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL))) 136 chan_send_eof2(ssh, c); 137 chan_set_istate(c, CHAN_INPUT_CLOSED); 138 break; 139 default: 140 error("channel %d: chan_ibuf_empty for istate %d", 141 c->self, c->istate); 142 break; 143 } 144 } 145 146 void 147 chan_obuf_empty(struct ssh *ssh, Channel *c) 148 { 149 debug2("channel %d: obuf empty", c->self); 150 if (sshbuf_len(c->output)) { 151 error("channel %d: chan_obuf_empty for non empty buffer", 152 c->self); 153 return; 154 } 155 switch (c->ostate) { 156 case CHAN_OUTPUT_WAIT_DRAIN: 157 chan_shutdown_write(ssh, c); 158 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 159 break; 160 default: 161 error("channel %d: internal error: obuf_empty for ostate %d", 162 c->self, c->ostate); 163 break; 164 } 165 } 166 167 void 168 chan_rcvd_eow(struct ssh *ssh, Channel *c) 169 { 170 debug2("channel %d: rcvd eow", c->self); 171 switch (c->istate) { 172 case CHAN_INPUT_OPEN: 173 chan_shutdown_read(ssh, c); 174 chan_set_istate(c, CHAN_INPUT_CLOSED); 175 break; 176 } 177 } 178 179 static void 180 chan_send_eof2(struct ssh *ssh, Channel *c) 181 { 182 int r; 183 184 debug2("channel %d: send eof", c->self); 185 switch (c->istate) { 186 case CHAN_INPUT_WAIT_DRAIN: 187 if (!c->have_remote_id) 188 fatal("%s: channel %d: no remote_id", 189 __func__, c->self); 190 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EOF)) != 0 || 191 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 192 (r = sshpkt_send(ssh)) != 0) 193 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 194 c->flags |= CHAN_EOF_SENT; 195 break; 196 default: 197 error("channel %d: cannot send eof for istate %d", 198 c->self, c->istate); 199 break; 200 } 201 } 202 203 static void 204 chan_send_close2(struct ssh *ssh, Channel *c) 205 { 206 int r; 207 208 debug2("channel %d: send close", c->self); 209 if (c->ostate != CHAN_OUTPUT_CLOSED || 210 c->istate != CHAN_INPUT_CLOSED) { 211 error("channel %d: cannot send close for istate/ostate %d/%d", 212 c->self, c->istate, c->ostate); 213 } else if (c->flags & CHAN_CLOSE_SENT) { 214 error("channel %d: already sent close", c->self); 215 } else { 216 if (!c->have_remote_id) 217 fatal("%s: channel %d: no remote_id", 218 __func__, c->self); 219 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 || 220 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 221 (r = sshpkt_send(ssh)) != 0) 222 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 223 c->flags |= CHAN_CLOSE_SENT; 224 } 225 } 226 227 static void 228 chan_send_eow2(struct ssh *ssh, Channel *c) 229 { 230 int r; 231 232 debug2("channel %d: send eow", c->self); 233 if (c->ostate == CHAN_OUTPUT_CLOSED) { 234 error("channel %d: must not sent eow on closed output", 235 c->self); 236 return; 237 } 238 if (!(datafellows & SSH_NEW_OPENSSH)) 239 return; 240 if (!c->have_remote_id) 241 fatal("%s: channel %d: no remote_id", __func__, c->self); 242 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 || 243 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 244 (r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 || 245 (r = sshpkt_put_u8(ssh, 0)) != 0 || 246 (r = sshpkt_send(ssh)) != 0) 247 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 248 } 249 250 /* shared */ 251 252 void 253 chan_rcvd_ieof(struct ssh *ssh, Channel *c) 254 { 255 debug2("channel %d: rcvd eof", c->self); 256 c->flags |= CHAN_EOF_RCVD; 257 if (c->ostate == CHAN_OUTPUT_OPEN) 258 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 259 if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && 260 sshbuf_len(c->output) == 0 && 261 !CHANNEL_EFD_OUTPUT_ACTIVE(c)) 262 chan_obuf_empty(ssh, c); 263 } 264 265 void 266 chan_rcvd_oclose(struct ssh *ssh, Channel *c) 267 { 268 debug2("channel %d: rcvd close", c->self); 269 if (!(c->flags & CHAN_LOCAL)) { 270 if (c->flags & CHAN_CLOSE_RCVD) 271 error("channel %d: protocol error: close rcvd twice", 272 c->self); 273 c->flags |= CHAN_CLOSE_RCVD; 274 } 275 if (c->type == SSH_CHANNEL_LARVAL) { 276 /* tear down larval channels immediately */ 277 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 278 chan_set_istate(c, CHAN_INPUT_CLOSED); 279 return; 280 } 281 switch (c->ostate) { 282 case CHAN_OUTPUT_OPEN: 283 /* 284 * wait until a data from the channel is consumed if a CLOSE 285 * is received 286 */ 287 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 288 break; 289 } 290 switch (c->istate) { 291 case CHAN_INPUT_OPEN: 292 chan_shutdown_read(ssh, c); 293 chan_shutdown_extended_read(ssh, c); 294 chan_set_istate(c, CHAN_INPUT_CLOSED); 295 break; 296 case CHAN_INPUT_WAIT_DRAIN: 297 if (!(c->flags & CHAN_LOCAL)) 298 chan_send_eof2(ssh, c); 299 chan_shutdown_extended_read(ssh, c); 300 chan_set_istate(c, CHAN_INPUT_CLOSED); 301 break; 302 } 303 } 304 305 void 306 chan_write_failed(struct ssh *ssh, Channel *c) 307 { 308 debug2("channel %d: write failed", c->self); 309 switch (c->ostate) { 310 case CHAN_OUTPUT_OPEN: 311 case CHAN_OUTPUT_WAIT_DRAIN: 312 chan_shutdown_write(ssh, c); 313 if (strcmp(c->ctype, "session") == 0) 314 chan_send_eow2(ssh, c); 315 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 316 break; 317 default: 318 error("channel %d: chan_write_failed for ostate %d", 319 c->self, c->ostate); 320 break; 321 } 322 } 323 324 void 325 chan_mark_dead(struct ssh *ssh, Channel *c) 326 { 327 c->type = SSH_CHANNEL_ZOMBIE; 328 } 329 330 int 331 chan_is_dead(struct ssh *ssh, Channel *c, int do_send) 332 { 333 if (c->type == SSH_CHANNEL_ZOMBIE) { 334 debug2("channel %d: zombie", c->self); 335 return 1; 336 } 337 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) 338 return 0; 339 if ((datafellows & SSH_BUG_EXTEOF) && 340 c->extended_usage == CHAN_EXTENDED_WRITE && 341 c->efd != -1 && 342 sshbuf_len(c->extended) > 0) { 343 debug2("channel %d: active efd: %d len %zu", 344 c->self, c->efd, sshbuf_len(c->extended)); 345 return 0; 346 } 347 if (c->flags & CHAN_LOCAL) { 348 debug2("channel %d: is dead (local)", c->self); 349 return 1; 350 } 351 if (!(c->flags & CHAN_CLOSE_SENT)) { 352 if (do_send) { 353 chan_send_close2(ssh, c); 354 } else { 355 /* channel would be dead if we sent a close */ 356 if (c->flags & CHAN_CLOSE_RCVD) { 357 debug2("channel %d: almost dead", 358 c->self); 359 return 1; 360 } 361 } 362 } 363 if ((c->flags & CHAN_CLOSE_SENT) && 364 (c->flags & CHAN_CLOSE_RCVD)) { 365 debug2("channel %d: is dead", c->self); 366 return 1; 367 } 368 return 0; 369 } 370 371 /* helper */ 372 static void 373 chan_shutdown_write(struct ssh *ssh, Channel *c) 374 { 375 sshbuf_reset(c->output); 376 if (c->type == SSH_CHANNEL_LARVAL) 377 return; 378 /* shutdown failure is allowed if write failed already */ 379 debug2("channel %d: %s (i%d o%d sock %d wfd %d efd %d [%s])", 380 c->self, __func__, c->istate, c->ostate, c->sock, c->wfd, c->efd, 381 channel_format_extended_usage(c)); 382 if (c->sock != -1) { 383 if (shutdown(c->sock, SHUT_WR) == -1) { 384 debug2("channel %d: %s: shutdown() failed for " 385 "fd %d [i%d o%d]: %.100s", c->self, __func__, 386 c->sock, c->istate, c->ostate, 387 strerror(errno)); 388 } 389 } else { 390 if (channel_close_fd(ssh, &c->wfd) < 0) { 391 logit("channel %d: %s: close() failed for " 392 "fd %d [i%d o%d]: %.100s", 393 c->self, __func__, c->wfd, c->istate, c->ostate, 394 strerror(errno)); 395 } 396 } 397 } 398 399 static void 400 chan_shutdown_read(struct ssh *ssh, Channel *c) 401 { 402 if (c->type == SSH_CHANNEL_LARVAL) 403 return; 404 debug2("channel %d: %s (i%d o%d sock %d wfd %d efd %d [%s])", 405 c->self, __func__, c->istate, c->ostate, c->sock, c->rfd, c->efd, 406 channel_format_extended_usage(c)); 407 if (c->sock != -1) { 408 /* 409 * shutdown(sock, SHUT_READ) may return ENOTCONN if the 410 * write side has been closed already. (bug on Linux) 411 * HP-UX may return ENOTCONN also. 412 */ 413 if (shutdown(c->sock, SHUT_RD) == -1 && errno != ENOTCONN) { 414 error("channel %d: %s: shutdown() failed for " 415 "fd %d [i%d o%d]: %.100s", 416 c->self, __func__, c->sock, c->istate, c->ostate, 417 strerror(errno)); 418 } 419 } else { 420 if (channel_close_fd(ssh, &c->rfd) < 0) { 421 logit("channel %d: %s: close() failed for " 422 "fd %d [i%d o%d]: %.100s", 423 c->self, __func__, c->rfd, c->istate, c->ostate, 424 strerror(errno)); 425 } 426 } 427 } 428 429 static void 430 chan_shutdown_extended_read(struct ssh *ssh, Channel *c) 431 { 432 if (c->type == SSH_CHANNEL_LARVAL || c->efd == -1) 433 return; 434 if (c->extended_usage != CHAN_EXTENDED_READ && 435 c->extended_usage != CHAN_EXTENDED_IGNORE) 436 return; 437 debug2("channel %d: %s (i%d o%d sock %d wfd %d efd %d [%s])", 438 c->self, __func__, c->istate, c->ostate, c->sock, c->rfd, c->efd, 439 channel_format_extended_usage(c)); 440 if (channel_close_fd(ssh, &c->efd) < 0) { 441 logit("channel %d: %s: close() failed for " 442 "extended fd %d [i%d o%d]: %.100s", 443 c->self, __func__, c->efd, c->istate, c->ostate, 444 strerror(errno)); 445 } 446 } 447