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
chan_set_istate(Channel * c,u_int next)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
chan_set_ostate(Channel * c,u_int next)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
chan_rcvd_oclose1(Channel * c)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
chan_read_failed(Channel * c)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
chan_ibuf_empty(Channel * c)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
chan_rcvd_ieof1(Channel * c)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
chan_write_failed1(Channel * c)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
chan_obuf_empty(Channel * c)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
chan_send_ieof1(Channel * c)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
chan_send_oclose1(Channel * c)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
chan_rcvd_close2(Channel * c)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
chan_rcvd_eow(Channel * c)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
chan_rcvd_eof2(Channel * c)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
chan_write_failed2(Channel * c)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
chan_send_eof2(Channel * c)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
chan_send_close2(Channel * c)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
chan_send_eow2(Channel * c)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
chan_rcvd_ieof(Channel * c)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
chan_rcvd_oclose(Channel * c)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
chan_write_failed(Channel * c)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
chan_mark_dead(Channel * c)436 chan_mark_dead(Channel *c)
437 {
438 c->type = SSH_CHANNEL_ZOMBIE;
439 }
440
441 int
chan_is_dead(Channel * c,int do_send)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
chan_shutdown_write(Channel * c)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
chan_shutdown_read(Channel * c)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 }
532