1 /* $OpenBSD: nchan.c,v 1.67 2017/09/12 06:35:32 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 "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 84 static const char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; 85 static const char *istates[] = { "open", "drain", "wait_oclose", "closed" }; 86 87 static void 88 chan_set_istate(Channel *c, u_int next) 89 { 90 if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) 91 fatal("chan_set_istate: bad state %d -> %d", c->istate, next); 92 debug2("channel %d: input %s -> %s", c->self, istates[c->istate], 93 istates[next]); 94 c->istate = next; 95 } 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 void 108 chan_read_failed(struct ssh *ssh, Channel *c) 109 { 110 debug2("channel %d: read failed", c->self); 111 switch (c->istate) { 112 case CHAN_INPUT_OPEN: 113 chan_shutdown_read(ssh, c); 114 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); 115 break; 116 default: 117 error("channel %d: chan_read_failed for istate %d", 118 c->self, c->istate); 119 break; 120 } 121 } 122 123 void 124 chan_ibuf_empty(struct ssh *ssh, Channel *c) 125 { 126 debug2("channel %d: ibuf empty", c->self); 127 if (sshbuf_len(c->input)) { 128 error("channel %d: chan_ibuf_empty for non empty buffer", 129 c->self); 130 return; 131 } 132 switch (c->istate) { 133 case CHAN_INPUT_WAIT_DRAIN: 134 if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL))) 135 chan_send_eof2(ssh, c); 136 chan_set_istate(c, CHAN_INPUT_CLOSED); 137 break; 138 default: 139 error("channel %d: chan_ibuf_empty for istate %d", 140 c->self, c->istate); 141 break; 142 } 143 } 144 145 void 146 chan_obuf_empty(struct ssh *ssh, Channel *c) 147 { 148 debug2("channel %d: obuf empty", c->self); 149 if (sshbuf_len(c->output)) { 150 error("channel %d: chan_obuf_empty for non empty buffer", 151 c->self); 152 return; 153 } 154 switch (c->ostate) { 155 case CHAN_OUTPUT_WAIT_DRAIN: 156 chan_shutdown_write(ssh, c); 157 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 158 break; 159 default: 160 error("channel %d: internal error: obuf_empty for ostate %d", 161 c->self, c->ostate); 162 break; 163 } 164 } 165 166 void 167 chan_rcvd_eow(struct ssh *ssh, Channel *c) 168 { 169 debug2("channel %d: rcvd eow", c->self); 170 switch (c->istate) { 171 case CHAN_INPUT_OPEN: 172 chan_shutdown_read(ssh, c); 173 chan_set_istate(c, CHAN_INPUT_CLOSED); 174 break; 175 } 176 } 177 178 static void 179 chan_send_eof2(struct ssh *ssh, Channel *c) 180 { 181 int r; 182 183 debug2("channel %d: send eof", c->self); 184 switch (c->istate) { 185 case CHAN_INPUT_WAIT_DRAIN: 186 if (!c->have_remote_id) 187 fatal("%s: channel %d: no remote_id", 188 __func__, c->self); 189 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EOF)) != 0 || 190 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 191 (r = sshpkt_send(ssh)) != 0) 192 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 193 c->flags |= CHAN_EOF_SENT; 194 break; 195 default: 196 error("channel %d: cannot send eof for istate %d", 197 c->self, c->istate); 198 break; 199 } 200 } 201 202 static void 203 chan_send_close2(struct ssh *ssh, Channel *c) 204 { 205 int r; 206 207 debug2("channel %d: send close", c->self); 208 if (c->ostate != CHAN_OUTPUT_CLOSED || 209 c->istate != CHAN_INPUT_CLOSED) { 210 error("channel %d: cannot send close for istate/ostate %d/%d", 211 c->self, c->istate, c->ostate); 212 } else if (c->flags & CHAN_CLOSE_SENT) { 213 error("channel %d: already sent close", c->self); 214 } else { 215 if (!c->have_remote_id) 216 fatal("%s: channel %d: no remote_id", 217 __func__, c->self); 218 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 || 219 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 220 (r = sshpkt_send(ssh)) != 0) 221 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 222 c->flags |= CHAN_CLOSE_SENT; 223 } 224 } 225 226 static void 227 chan_send_eow2(struct ssh *ssh, Channel *c) 228 { 229 int r; 230 231 debug2("channel %d: send eow", c->self); 232 if (c->ostate == CHAN_OUTPUT_CLOSED) { 233 error("channel %d: must not sent eow on closed output", 234 c->self); 235 return; 236 } 237 if (!(datafellows & SSH_NEW_OPENSSH)) 238 return; 239 if (!c->have_remote_id) 240 fatal("%s: channel %d: no remote_id", __func__, c->self); 241 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 || 242 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 243 (r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 || 244 (r = sshpkt_put_u8(ssh, 0)) != 0 || 245 (r = sshpkt_send(ssh)) != 0) 246 fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r)); 247 } 248 249 /* shared */ 250 251 void 252 chan_rcvd_ieof(struct ssh *ssh, Channel *c) 253 { 254 debug2("channel %d: rcvd eof", c->self); 255 c->flags |= CHAN_EOF_RCVD; 256 if (c->ostate == CHAN_OUTPUT_OPEN) 257 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 258 if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && 259 sshbuf_len(c->output) == 0 && 260 !CHANNEL_EFD_OUTPUT_ACTIVE(c)) 261 chan_obuf_empty(ssh, c); 262 } 263 264 void 265 chan_rcvd_oclose(struct ssh *ssh, Channel *c) 266 { 267 debug2("channel %d: rcvd close", c->self); 268 if (!(c->flags & CHAN_LOCAL)) { 269 if (c->flags & CHAN_CLOSE_RCVD) 270 error("channel %d: protocol error: close rcvd twice", 271 c->self); 272 c->flags |= CHAN_CLOSE_RCVD; 273 } 274 if (c->type == SSH_CHANNEL_LARVAL) { 275 /* tear down larval channels immediately */ 276 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 277 chan_set_istate(c, CHAN_INPUT_CLOSED); 278 return; 279 } 280 switch (c->ostate) { 281 case CHAN_OUTPUT_OPEN: 282 /* 283 * wait until a data from the channel is consumed if a CLOSE 284 * is received 285 */ 286 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 287 break; 288 } 289 switch (c->istate) { 290 case CHAN_INPUT_OPEN: 291 chan_shutdown_read(ssh, c); 292 chan_set_istate(c, CHAN_INPUT_CLOSED); 293 break; 294 case CHAN_INPUT_WAIT_DRAIN: 295 if (!(c->flags & CHAN_LOCAL)) 296 chan_send_eof2(ssh, c); 297 chan_set_istate(c, CHAN_INPUT_CLOSED); 298 break; 299 } 300 } 301 302 void 303 chan_write_failed(struct ssh *ssh, Channel *c) 304 { 305 debug2("channel %d: write failed", c->self); 306 switch (c->ostate) { 307 case CHAN_OUTPUT_OPEN: 308 case CHAN_OUTPUT_WAIT_DRAIN: 309 chan_shutdown_write(ssh, c); 310 if (strcmp(c->ctype, "session") == 0) 311 chan_send_eow2(ssh, c); 312 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 313 break; 314 default: 315 error("channel %d: chan_write_failed for ostate %d", 316 c->self, c->ostate); 317 break; 318 } 319 } 320 321 void 322 chan_mark_dead(struct ssh *ssh, Channel *c) 323 { 324 c->type = SSH_CHANNEL_ZOMBIE; 325 } 326 327 int 328 chan_is_dead(struct ssh *ssh, Channel *c, int do_send) 329 { 330 if (c->type == SSH_CHANNEL_ZOMBIE) { 331 debug2("channel %d: zombie", c->self); 332 return 1; 333 } 334 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) 335 return 0; 336 if ((datafellows & SSH_BUG_EXTEOF) && 337 c->extended_usage == CHAN_EXTENDED_WRITE && 338 c->efd != -1 && 339 sshbuf_len(c->extended) > 0) { 340 debug2("channel %d: active efd: %d len %zu", 341 c->self, c->efd, sshbuf_len(c->extended)); 342 return 0; 343 } 344 if (c->flags & CHAN_LOCAL) { 345 debug2("channel %d: is dead (local)", c->self); 346 return 1; 347 } 348 if (!(c->flags & CHAN_CLOSE_SENT)) { 349 if (do_send) { 350 chan_send_close2(ssh, c); 351 } else { 352 /* channel would be dead if we sent a close */ 353 if (c->flags & CHAN_CLOSE_RCVD) { 354 debug2("channel %d: almost dead", 355 c->self); 356 return 1; 357 } 358 } 359 } 360 if ((c->flags & CHAN_CLOSE_SENT) && 361 (c->flags & CHAN_CLOSE_RCVD)) { 362 debug2("channel %d: is dead", c->self); 363 return 1; 364 } 365 return 0; 366 } 367 368 /* helper */ 369 static void 370 chan_shutdown_write(struct ssh *ssh, Channel *c) 371 { 372 sshbuf_reset(c->output); 373 if (c->type == SSH_CHANNEL_LARVAL) 374 return; 375 /* shutdown failure is allowed if write failed already */ 376 debug2("channel %d: close_write", c->self); 377 if (c->sock != -1) { 378 if (shutdown(c->sock, SHUT_WR) < 0) 379 debug2("channel %d: chan_shutdown_write: " 380 "shutdown() failed for fd %d: %.100s", 381 c->self, c->sock, strerror(errno)); 382 } else { 383 if (channel_close_fd(ssh, &c->wfd) < 0) 384 logit("channel %d: chan_shutdown_write: " 385 "close() failed for fd %d: %.100s", 386 c->self, c->wfd, strerror(errno)); 387 } 388 } 389 390 static void 391 chan_shutdown_read(struct ssh *ssh, Channel *c) 392 { 393 if (c->type == SSH_CHANNEL_LARVAL) 394 return; 395 debug2("channel %d: close_read", c->self); 396 if (c->sock != -1) { 397 /* 398 * shutdown(sock, SHUT_READ) may return ENOTCONN if the 399 * write side has been closed already. (bug on Linux) 400 * HP-UX may return ENOTCONN also. 401 */ 402 if (shutdown(c->sock, SHUT_RD) < 0 403 && errno != ENOTCONN) 404 error("channel %d: chan_shutdown_read: " 405 "shutdown() failed for fd %d [i%d o%d]: %.100s", 406 c->self, c->sock, c->istate, c->ostate, 407 strerror(errno)); 408 } else { 409 if (channel_close_fd(ssh, &c->rfd) < 0) 410 logit("channel %d: chan_shutdown_read: " 411 "close() failed for fd %d: %.100s", 412 c->self, c->rfd, strerror(errno)); 413 } 414 } 415