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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 | } |