1 /*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5 * This file contains functions for generic socket connection forwarding.
6 * There is also code for initiating connection forwarding for X11 connections,
7 * arbitrary tcp/ip connections, and the authentication agent connection.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 * SSH2 support added by Markus Friedl.
16 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
17 * Copyright (c) 1999 Dug Song. All rights reserved.
18 * Copyright (c) 1999 Theo de Raadt. All rights reserved.
19 *
20 * Redistribution and use in source and binary forms, with or without
21 * modification, are permitted provided that the following conditions
22 * are met:
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
25 * 2. Redistributions in binary form must reproduce the above copyright
26 * notice, this list of conditions and the following disclaimer in the
27 * documentation and/or other materials provided with the distribution.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 */
40 /*
41 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
42 */
43
44 #include "includes.h"
45 RCSID("$OpenBSD: channels.c,v 1.183 2002/09/17 07:47:02 itojun Exp $");
46
47 #include "ssh.h"
48 #include "ssh1.h"
49 #include "ssh2.h"
50 #include "packet.h"
51 #include "xmalloc.h"
52 #include "log.h"
53 #include "misc.h"
54 #include "channels.h"
55 #include "compat.h"
56 #include "canohost.h"
57 #include "key.h"
58 #include "authfd.h"
59 #include "pathnames.h"
60 #include "bufaux.h"
61
62
63 /* -- channel core */
64
65 /*
66 * Pointer to an array containing all allocated channels. The array is
67 * dynamically extended as needed.
68 */
69 static Channel **channels = NULL;
70
71 /*
72 * Size of the channel array. All slots of the array must always be
73 * initialized (at least the type field); unused slots set to NULL
74 */
75 static int channels_alloc = 0;
76
77 /*
78 * Maximum file descriptor value used in any of the channels. This is
79 * updated in channel_new.
80 */
81 static int channel_max_fd = 0;
82
83
84 /* -- tcp forwarding */
85
86 /*
87 * Data structure for storing which hosts are permitted for forward requests.
88 * The local sides of any remote forwards are stored in this array to prevent
89 * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
90 * network (which might be behind a firewall).
91 */
92 typedef struct {
93 char *host_to_connect; /* Connect to 'host'. */
94 u_short port_to_connect; /* Connect to 'port'. */
95 u_short listen_port; /* Remote side should listen port number. */
96 } ForwardPermission;
97
98 /* List of all permitted host/port pairs to connect. */
99 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
100
101 /* Number of permitted host/port pairs in the array. */
102 static int num_permitted_opens = 0;
103 /*
104 * If this is true, all opens are permitted. This is the case on the server
105 * on which we have to trust the client anyway, and the user could do
106 * anything after logging in anyway.
107 */
108 static int all_opens_permitted = 0;
109
110
111 /* -- X11 forwarding */
112
113 /* Maximum number of fake X11 displays to try. */
114 #define MAX_DISPLAYS 1000
115
116 /* Saved X11 authentication protocol name. */
117 static char *x11_saved_proto = NULL;
118
119 /* Saved X11 authentication data. This is the real data. */
120 static char *x11_saved_data = NULL;
121 static u_int x11_saved_data_len = 0;
122
123 /*
124 * Fake X11 authentication data. This is what the server will be sending us;
125 * we should replace any occurrences of this by the real data.
126 */
127 static u_char *x11_fake_data = NULL;
128 static u_int x11_fake_data_len;
129
130
131 /* -- agent forwarding */
132
133 #define NUM_SOCKS 10
134
135 /* AF_UNSPEC or AF_INET or AF_INET6 */
136 static int IPv4or6 = AF_UNSPEC;
137
138 /* helper */
139 static void port_open_helper(Channel *c, char *rtype);
140
141 /* -- channel core */
142
143 Channel *
144 channel_lookup(int id)
145 {
146 Channel *c;
147
148 if (id < 0 || id >= channels_alloc) {
149 log("channel_lookup: %d: bad id", id);
150 return NULL;
151 }
152 c = channels[id];
153 if (c == NULL) {
154 log("channel_lookup: %d: bad id: channel free", id);
155 return NULL;
156 }
157 return c;
158 }
159
160 /*
161 * Register filedescriptors for a channel, used when allocating a channel or
162 * when the channel consumer/producer is ready, e.g. shell exec'd
163 */
164
165 static void
166 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
167 int extusage, int nonblock)
168 {
169 /* Update the maximum file descriptor value. */
170 channel_max_fd = MAX(channel_max_fd, rfd);
171 channel_max_fd = MAX(channel_max_fd, wfd);
172 channel_max_fd = MAX(channel_max_fd, efd);
173
174 /* XXX set close-on-exec -markus */
175
176 c->rfd = rfd;
177 c->wfd = wfd;
178 c->sock = (rfd == wfd) ? rfd : -1;
179 c->efd = efd;
180 c->extended_usage = extusage;
181
182 /* XXX ugly hack: nonblock is only set by the server */
183 if (nonblock && isatty(c->rfd)) {
184 debug("channel %d: rfd %d isatty", c->self, c->rfd);
185 c->isatty = 1;
186 if (!isatty(c->wfd)) {
187 error("channel %d: wfd %d is not a tty?",
188 c->self, c->wfd);
189 }
190 } else {
191 c->isatty = 0;
192 }
193 c->wfd_isatty = isatty(c->wfd);
194
195 /* enable nonblocking mode */
196 if (nonblock) {
197 if (rfd != -1)
198 set_nonblock(rfd);
199 if (wfd != -1)
200 set_nonblock(wfd);
201 if (efd != -1)
202 set_nonblock(efd);
203 }
204 }
205
206 /*
207 * Allocate a new channel object and set its type and socket. This will cause
208 * remote_name to be freed.
209 */
210
211 Channel *
212 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
213 u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
214 {
215 int i, found;
216 Channel *c;
217
218 /* Do initial allocation if this is the first call. */
219 if (channels_alloc == 0) {
220 channels_alloc = 10;
221 channels = xmalloc(channels_alloc * sizeof(Channel *));
222 for (i = 0; i < channels_alloc; i++)
223 channels[i] = NULL;
224 fatal_add_cleanup((void (*) (void *)) channel_free_all, NULL);
225 }
226 /* Try to find a free slot where to put the new channel. */
227 for (found = -1, i = 0; i < channels_alloc; i++)
228 if (channels[i] == NULL) {
229 /* Found a free slot. */
230 found = i;
231 break;
232 }
233 if (found == -1) {
234 /* There are no free slots. Take last+1 slot and expand the array. */
235 found = channels_alloc;
236 if (channels_alloc > 10000)
237 fatal("channel_new: internal error: channels_alloc %d "
238 "too big.", channels_alloc);
239 channels = xrealloc(channels,
240 (channels_alloc + 10) * sizeof(Channel *));
241 channels_alloc += 10;
242 debug2("channel: expanding %d", channels_alloc);
243 for (i = found; i < channels_alloc; i++)
244 channels[i] = NULL;
245 }
246 /* Initialize and return new channel. */
247 c = channels[found] = xmalloc(sizeof(Channel));
248 memset(c, 0, sizeof(Channel));
249 buffer_init(&c->input);
250 buffer_init(&c->output);
251 buffer_init(&c->extended);
252 c->ostate = CHAN_OUTPUT_OPEN;
253 c->istate = CHAN_INPUT_OPEN;
254 c->flags = 0;
255 channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
256 c->self = found;
257 c->type = type;
258 c->ctype = ctype;
259 c->local_window = window;
260 c->local_window_max = window;
261 c->local_consumed = 0;
262 c->local_maxpacket = maxpack;
263 c->remote_id = -1;
264 c->remote_name = remote_name;
265 c->remote_window = 0;
266 c->remote_maxpacket = 0;
267 c->force_drain = 0;
268 c->single_connection = 0;
269 c->detach_user = NULL;
270 c->confirm = NULL;
271 c->input_filter = NULL;
272 c->delayed = 1; /* prevent call to channel_post handler */
273 debug("channel %d: new [%s]", found, remote_name);
274 return c;
275 }
276
277 static int
278 channel_find_maxfd(void)
279 {
280 int i, max = 0;
281 Channel *c;
282
283 for (i = 0; i < channels_alloc; i++) {
284 c = channels[i];
285 if (c != NULL) {
286 max = MAX(max, c->rfd);
287 max = MAX(max, c->wfd);
288 max = MAX(max, c->efd);
289 }
290 }
291 return max;
292 }
293
294 int
295 channel_close_fd(int *fdp)
296 {
297 int ret = 0, fd = *fdp;
298
299 if (fd != -1) {
300 ret = close(fd);
301 *fdp = -1;
302 if (fd == channel_max_fd)
303 channel_max_fd = channel_find_maxfd();
304 }
305 return ret;
306 }
307
308 /* Close all channel fd/socket. */
309
310 static void
311 channel_close_fds(Channel *c)
312 {
313 debug3("channel_close_fds: channel %d: r %d w %d e %d",
314 c->self, c->rfd, c->wfd, c->efd);
315
316 channel_close_fd(&c->sock);
317 channel_close_fd(&c->rfd);
318 channel_close_fd(&c->wfd);
319 channel_close_fd(&c->efd);
320 }
321
322 /* Free the channel and close its fd/socket. */
323
324 void
325 channel_free(Channel *c)
326 {
327 char *s;
328 int i, n;
329
330 for (n = 0, i = 0; i < channels_alloc; i++)
331 if (channels[i])
332 n++;
333 debug("channel_free: channel %d: %s, nchannels %d", c->self,
334 c->remote_name ? c->remote_name : "???", n);
335
336 s = channel_open_message();
337 debug3("channel_free: status: %s", s);
338 xfree(s);
339
340 if (c->sock != -1)
341 shutdown(c->sock, SHUT_RDWR);
342 channel_close_fds(c);
343 buffer_free(&c->input);
344 buffer_free(&c->output);
345 buffer_free(&c->extended);
346 if (c->remote_name) {
347 xfree(c->remote_name);
348 c->remote_name = NULL;
349 }
350 channels[c->self] = NULL;
351 xfree(c);
352 }
353
354 void
355 channel_free_all(void)
356 {
357 int i;
358
359 for (i = 0; i < channels_alloc; i++)
360 if (channels[i] != NULL)
361 channel_free(channels[i]);
362 }
363
364 /*
365 * Closes the sockets/fds of all channels. This is used to close extra file
366 * descriptors after a fork.
367 */
368
369 void
370 channel_close_all(void)
371 {
372 int i;
373
374 for (i = 0; i < channels_alloc; i++)
375 if (channels[i] != NULL)
376 channel_close_fds(channels[i]);
377 }
378
379 /*
380 * Stop listening to channels.
381 */
382
383 void
384 channel_stop_listening(void)
385 {
386 int i;
387 Channel *c;
388
389 for (i = 0; i < channels_alloc; i++) {
390 c = channels[i];
391 if (c != NULL) {
392 switch (c->type) {
393 case SSH_CHANNEL_AUTH_SOCKET:
394 case SSH_CHANNEL_PORT_LISTENER:
395 case SSH_CHANNEL_RPORT_LISTENER:
396 case SSH_CHANNEL_X11_LISTENER:
397 channel_close_fd(&c->sock);
398 channel_free(c);
399 break;
400 }
401 }
402 }
403 }
404
405 /*
406 * Returns true if no channel has too much buffered data, and false if one or
407 * more channel is overfull.
408 */
409
410 int
411 channel_not_very_much_buffered_data(void)
412 {
413 u_int i;
414 Channel *c;
415
416 for (i = 0; i < channels_alloc; i++) {
417 c = channels[i];
418 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
419 #if 0
420 if (!compat20 &&
421 buffer_len(&c->input) > packet_get_maxsize()) {
422 debug("channel %d: big input buffer %d",
423 c->self, buffer_len(&c->input));
424 return 0;
425 }
426 #endif
427 if (buffer_len(&c->output) > packet_get_maxsize()) {
428 debug("channel %d: big output buffer %d > %d",
429 c->self, buffer_len(&c->output),
430 packet_get_maxsize());
431 return 0;
432 }
433 }
434 }
435 return 1;
436 }
437
438 /* Returns true if any channel is still open. */
439
440 int
441 channel_still_open(void)
442 {
443 int i;
444 Channel *c;
445
446 for (i = 0; i < channels_alloc; i++) {
447 c = channels[i];
448 if (c == NULL)
449 continue;
450 switch (c->type) {
451 case SSH_CHANNEL_X11_LISTENER:
452 case SSH_CHANNEL_PORT_LISTENER:
453 case SSH_CHANNEL_RPORT_LISTENER:
454 case SSH_CHANNEL_CLOSED:
455 case SSH_CHANNEL_AUTH_SOCKET:
456 case SSH_CHANNEL_DYNAMIC:
457 case SSH_CHANNEL_CONNECTING:
458 case SSH_CHANNEL_ZOMBIE:
459 continue;
460 case SSH_CHANNEL_LARVAL:
461 if (!compat20)
462 fatal("cannot happen: SSH_CHANNEL_LARVAL");
463 continue;
464 case SSH_CHANNEL_OPENING:
465 case SSH_CHANNEL_OPEN:
466 case SSH_CHANNEL_X11_OPEN:
467 return 1;
468 case SSH_CHANNEL_INPUT_DRAINING:
469 case SSH_CHANNEL_OUTPUT_DRAINING:
470 if (!compat13)
471 fatal("cannot happen: OUT_DRAIN");
472 return 1;
473 default:
474 fatal("channel_still_open: bad channel type %d", c->type);
475 /* NOTREACHED */
476 }
477 }
478 return 0;
479 }
480
481 /* Returns the id of an open channel suitable for keepaliving */
482
483 int
484 channel_find_open(void)
485 {
486 int i;
487 Channel *c;
488
489 for (i = 0; i < channels_alloc; i++) {
490 c = channels[i];
491 if (c == NULL)
492 continue;
493 switch (c->type) {
494 case SSH_CHANNEL_CLOSED:
495 case SSH_CHANNEL_DYNAMIC:
496 case SSH_CHANNEL_X11_LISTENER:
497 case SSH_CHANNEL_PORT_LISTENER:
498 case SSH_CHANNEL_RPORT_LISTENER:
499 case SSH_CHANNEL_OPENING:
500 case SSH_CHANNEL_CONNECTING:
501 case SSH_CHANNEL_ZOMBIE:
502 continue;
503 case SSH_CHANNEL_LARVAL:
504 case SSH_CHANNEL_AUTH_SOCKET:
505 case SSH_CHANNEL_OPEN:
506 case SSH_CHANNEL_X11_OPEN:
507 return i;
508 case SSH_CHANNEL_INPUT_DRAINING:
509 case SSH_CHANNEL_OUTPUT_DRAINING:
510 if (!compat13)
511 fatal("cannot happen: OUT_DRAIN");
512 return i;
513 default:
514 fatal("channel_find_open: bad channel type %d", c->type);
515 /* NOTREACHED */
516 }
517 }
518 return -1;
519 }
520
521
522 /*
523 * Returns a message describing the currently open forwarded connections,
524 * suitable for sending to the client. The message contains crlf pairs for
525 * newlines.
526 */
527
528 char *
529 channel_open_message(void)
530 {
531 Buffer buffer;
532 Channel *c;
533 char buf[1024], *cp;
534 int i;
535
536 buffer_init(&buffer);
537 snprintf(buf, sizeof buf, "The following connections are open:\r\n");
538 buffer_append(&buffer, buf, strlen(buf));
539 for (i = 0; i < channels_alloc; i++) {
540 c = channels[i];
541 if (c == NULL)
542 continue;
543 switch (c->type) {
544 case SSH_CHANNEL_X11_LISTENER:
545 case SSH_CHANNEL_PORT_LISTENER:
546 case SSH_CHANNEL_RPORT_LISTENER:
547 case SSH_CHANNEL_CLOSED:
548 case SSH_CHANNEL_AUTH_SOCKET:
549 case SSH_CHANNEL_ZOMBIE:
550 continue;
551 case SSH_CHANNEL_LARVAL:
552 case SSH_CHANNEL_OPENING:
553 case SSH_CHANNEL_CONNECTING:
554 case SSH_CHANNEL_DYNAMIC:
555 case SSH_CHANNEL_OPEN:
556 case SSH_CHANNEL_X11_OPEN:
557 case SSH_CHANNEL_INPUT_DRAINING:
558 case SSH_CHANNEL_OUTPUT_DRAINING:
559 snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
560 c->self, c->remote_name,
561 c->type, c->remote_id,
562 c->istate, buffer_len(&c->input),
563 c->ostate, buffer_len(&c->output),
564 c->rfd, c->wfd);
565 buffer_append(&buffer, buf, strlen(buf));
566 continue;
567 default:
568 fatal("channel_open_message: bad channel type %d", c->type);
569 /* NOTREACHED */
570 }
571 }
572 buffer_append(&buffer, "\0", 1);
573 cp = xstrdup(buffer_ptr(&buffer));
574 buffer_free(&buffer);
575 return cp;
576 }
577
578 void
579 channel_send_open(int id)
580 {
581 Channel *c = channel_lookup(id);
582
583 if (c == NULL) {
584 log("channel_send_open: %d: bad id", id);
585 return;
586 }
587 debug("send channel open %d", id);
588 packet_start(SSH2_MSG_CHANNEL_OPEN);
589 packet_put_cstring(c->ctype);
590 packet_put_int(c->self);
591 packet_put_int(c->local_window);
592 packet_put_int(c->local_maxpacket);
593 packet_send();
594 }
595
596 void
597 channel_request_start(int local_id, char *service, int wantconfirm)
598 {
599 Channel *c = channel_lookup(local_id);
600
601 debug("channel request %d: %s", local_id, service);
602 if (c == NULL) {
603 log("channel_request_start: %d: unknown channel id", local_id);
604 return;
605 }
606 packet_start(SSH2_MSG_CHANNEL_REQUEST);
607 packet_put_int(c->remote_id);
608 packet_put_cstring(service);
609 packet_put_char(wantconfirm);
610 }
611 void
612 channel_register_confirm(int id, channel_callback_fn *fn)
613 {
614 Channel *c = channel_lookup(id);
615
616 if (c == NULL) {
617 log("channel_register_comfirm: %d: bad id", id);
618 return;
619 }
620 c->confirm = fn;
621 }
622 void
623 channel_register_cleanup(int id, channel_callback_fn *fn)
624 {
625 Channel *c = channel_lookup(id);
626
627 if (c == NULL) {
628 log("channel_register_cleanup: %d: bad id", id);
629 return;
630 }
631 c->detach_user = fn;
632 }
633 void
634 channel_cancel_cleanup(int id)
635 {
636 Channel *c = channel_lookup(id);
637
638 if (c == NULL) {
639 log("channel_cancel_cleanup: %d: bad id", id);
640 return;
641 }
642 c->detach_user = NULL;
643 }
644 void
645 channel_register_filter(int id, channel_filter_fn *fn)
646 {
647 Channel *c = channel_lookup(id);
648
649 if (c == NULL) {
650 log("channel_register_filter: %d: bad id", id);
651 return;
652 }
653 c->input_filter = fn;
654 }
655
656 void
657 channel_set_fds(int id, int rfd, int wfd, int efd,
658 int extusage, int nonblock, u_int window_max)
659 {
660 Channel *c = channel_lookup(id);
661
662 if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
663 fatal("channel_activate for non-larval channel %d.", id);
664 channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
665 c->type = SSH_CHANNEL_OPEN;
666 c->local_window = c->local_window_max = window_max;
667 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
668 packet_put_int(c->remote_id);
669 packet_put_int(c->local_window);
670 packet_send();
671 }
672
673 void
674 channel_set_wait_for_exit(int id, int wait_for_exit)
675 {
676 Channel *c = channel_lookup(id);
677
678 if (c == NULL || c->type != SSH_CHANNEL_OPEN)
679 fatal("channel_set_wait_for_exit for non-open channel %d.", id);
680
681 debug3("channel_set_wait_for_exit %d, %d (type: %d)", id, wait_for_exit, c->type);
682 c->wait_for_exit = wait_for_exit;
683 }
684
685 /*
686 * 'channel_pre*' are called just before select() to add any bits relevant to
687 * channels in the select bitmasks.
688 */
689 /*
690 * 'channel_post*': perform any appropriate operations for channels which
691 * have events pending.
692 */
693 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
694 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
695 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
696
697 static void
698 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
699 {
700 FD_SET(c->sock, readset);
701 }
702
703 static void
704 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
705 {
706 debug3("channel %d: waiting for connection", c->self);
707 FD_SET(c->sock, writeset);
708 }
709
710 static void
711 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
712 {
713 if (buffer_len(&c->input) < packet_get_maxsize())
714 FD_SET(c->sock, readset);
715 if (buffer_len(&c->output) > 0)
716 FD_SET(c->sock, writeset);
717 }
718
719 static void
720 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
721 {
722 u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
723
724 if (c->istate == CHAN_INPUT_OPEN &&
725 limit > 0 &&
726 buffer_len(&c->input) < limit &&
727 buffer_check_alloc(&c->input, CHAN_RBUF))
728 FD_SET(c->rfd, readset);
729 if (c->ostate == CHAN_OUTPUT_OPEN ||
730 c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
731 if (buffer_len(&c->output) > 0) {
732 FD_SET(c->wfd, writeset);
733 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
734 if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
735 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
736 c->self, c->efd, buffer_len(&c->extended));
737 else
738 chan_obuf_empty(c);
739 }
740 }
741 /** XXX check close conditions, too */
742 if (compat20 && c->efd != -1) {
743 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
744 buffer_len(&c->extended) > 0)
745 FD_SET(c->efd, writeset);
746 else if (!(c->flags & CHAN_EOF_SENT) &&
747 c->extended_usage == CHAN_EXTENDED_READ &&
748 buffer_len(&c->extended) < c->remote_window)
749 FD_SET(c->efd, readset);
750 }
751 }
752
753 static void
754 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
755 {
756 if (buffer_len(&c->input) == 0) {
757 packet_start(SSH_MSG_CHANNEL_CLOSE);
758 packet_put_int(c->remote_id);
759 packet_send();
760 c->type = SSH_CHANNEL_CLOSED;
761 debug("channel %d: closing after input drain.", c->self);
762 }
763 }
764
765 static void
766 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
767 {
768 if (buffer_len(&c->output) == 0)
769 chan_mark_dead(c);
770 else
771 FD_SET(c->sock, writeset);
772 }
773
774 /*
775 * This is a special state for X11 authentication spoofing. An opened X11
776 * connection (when authentication spoofing is being done) remains in this
777 * state until the first packet has been completely read. The authentication
778 * data in that packet is then substituted by the real data if it matches the
779 * fake data, and the channel is put into normal mode.
780 * XXX All this happens at the client side.
781 * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
782 */
783 static int
784 x11_open_helper(Buffer *b)
785 {
786 u_char *ucp;
787 u_int proto_len, data_len;
788
789 /* Check if the fixed size part of the packet is in buffer. */
790 if (buffer_len(b) < 12)
791 return 0;
792
793 /* Parse the lengths of variable-length fields. */
794 ucp = buffer_ptr(b);
795 if (ucp[0] == 0x42) { /* Byte order MSB first. */
796 proto_len = 256 * ucp[6] + ucp[7];
797 data_len = 256 * ucp[8] + ucp[9];
798 } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
799 proto_len = ucp[6] + 256 * ucp[7];
800 data_len = ucp[8] + 256 * ucp[9];
801 } else {
802 debug("Initial X11 packet contains bad byte order byte: 0x%x",
803 ucp[0]);
804 return -1;
805 }
806
807 /* Check if the whole packet is in buffer. */
808 if (buffer_len(b) <
809 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
810 return 0;
811
812 /* Check if authentication protocol matches. */
813 if (proto_len != strlen(x11_saved_proto) ||
814 memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
815 debug("X11 connection uses different authentication protocol.");
816 return -1;
817 }
818 /* Check if authentication data matches our fake data. */
819 if (data_len != x11_fake_data_len ||
820 memcmp(ucp + 12 + ((proto_len + 3) & ~3),
821 x11_fake_data, x11_fake_data_len) != 0) {
822 debug("X11 auth data does not match fake data.");
823 return -1;
824 }
825 /* Check fake data length */
826 if (x11_fake_data_len != x11_saved_data_len) {
827 error("X11 fake_data_len %d != saved_data_len %d",
828 x11_fake_data_len, x11_saved_data_len);
829 return -1;
830 }
831 /*
832 * Received authentication protocol and data match
833 * our fake data. Substitute the fake data with real
834 * data.
835 */
836 memcpy(ucp + 12 + ((proto_len + 3) & ~3),
837 x11_saved_data, x11_saved_data_len);
838 return 1;
839 }
840
841 static void
842 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
843 {
844 int ret = x11_open_helper(&c->output);
845
846 if (ret == 1) {
847 /* Start normal processing for the channel. */
848 c->type = SSH_CHANNEL_OPEN;
849 channel_pre_open_13(c, readset, writeset);
850 } else if (ret == -1) {
851 /*
852 * We have received an X11 connection that has bad
853 * authentication information.
854 */
855 log("X11 connection rejected because of wrong authentication.");
856 buffer_clear(&c->input);
857 buffer_clear(&c->output);
858 channel_close_fd(&c->sock);
859 c->sock = -1;
860 c->type = SSH_CHANNEL_CLOSED;
861 packet_start(SSH_MSG_CHANNEL_CLOSE);
862 packet_put_int(c->remote_id);
863 packet_send();
864 }
865 }
866
867 static void
868 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
869 {
870 int ret = x11_open_helper(&c->output);
871
872 /* c->force_drain = 1; */
873
874 if (ret == 1) {
875 c->type = SSH_CHANNEL_OPEN;
876 channel_pre_open(c, readset, writeset);
877 } else if (ret == -1) {
878 log("X11 connection rejected because of wrong authentication.");
879 debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
880 chan_read_failed(c);
881 buffer_clear(&c->input);
882 chan_ibuf_empty(c);
883 buffer_clear(&c->output);
884 /* for proto v1, the peer will send an IEOF */
885 if (compat20)
886 chan_write_failed(c);
887 else
888 c->type = SSH_CHANNEL_OPEN;
889 debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
890 }
891 }
892
893 /* try to decode a socks4 header */
894 static int
895 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
896 {
897 char *p, *host;
898 int len, have, i, found;
899 char username[256];
900 struct {
901 u_int8_t version;
902 u_int8_t command;
903 u_int16_t dest_port;
904 struct in_addr dest_addr;
905 } s4_req, s4_rsp;
906
907 debug2("channel %d: decode socks4", c->self);
908
909 have = buffer_len(&c->input);
910 len = sizeof(s4_req);
911 if (have < len)
912 return 0;
913 p = buffer_ptr(&c->input);
914 for (found = 0, i = len; i < have; i++) {
915 if (p[i] == '\0') {
916 found = 1;
917 break;
918 }
919 if (i > 1024) {
920 /* the peer is probably sending garbage */
921 debug("channel %d: decode socks4: too long",
922 c->self);
923 return -1;
924 }
925 }
926 if (!found)
927 return 0;
928 buffer_get(&c->input, (char *)&s4_req.version, 1);
929 buffer_get(&c->input, (char *)&s4_req.command, 1);
930 buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
931 buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
932 have = buffer_len(&c->input);
933 p = buffer_ptr(&c->input);
934 len = strlen(p);
935 debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
936 if (len > have)
937 fatal("channel %d: decode socks4: len %d > have %d",
938 c->self, len, have);
939 strlcpy(username, p, sizeof(username));
940 buffer_consume(&c->input, len);
941 buffer_consume(&c->input, 1); /* trailing '\0' */
942
943 host = inet_ntoa(s4_req.dest_addr);
944 strlcpy(c->path, host, sizeof(c->path));
945 c->host_port = ntohs(s4_req.dest_port);
946
947 debug("channel %d: dynamic request: socks4 host %s port %u command %u",
948 c->self, host, c->host_port, s4_req.command);
949
950 if (s4_req.command != 1) {
951 debug("channel %d: cannot handle: socks4 cn %d",
952 c->self, s4_req.command);
953 return -1;
954 }
955 s4_rsp.version = 0; /* vn: 0 for reply */
956 s4_rsp.command = 90; /* cd: req granted */
957 s4_rsp.dest_port = 0; /* ignored */
958 s4_rsp.dest_addr.s_addr = INADDR_ANY; /* ignored */
959 buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
960 return 1;
961 }
962
963 /* try to decode a socks5 header */
964 #define SSH_SOCKS5_AUTHDONE 0x1000
965 #define SSH_SOCKS5_NOAUTH 0x00
966 #define SSH_SOCKS5_IPV4 0x01
967 #define SSH_SOCKS5_DOMAIN 0x03
968 #define SSH_SOCKS5_IPV6 0x04
969 #define SSH_SOCKS5_CONNECT 0x01
970 #define SSH_SOCKS5_SUCCESS 0x00
971
972 /* ARGSUSED */
973 static int
974 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
975 {
976 struct {
977 u_int8_t version;
978 u_int8_t command;
979 u_int8_t reserved;
980 u_int8_t atyp;
981 } s5_req, s5_rsp;
982 u_int16_t dest_port;
983 u_char *p, dest_addr[255+1];
984 u_int have, need, i, found, nmethods, addrlen;
985 struct in_addr bnd_addr;
986 int af;
987
988 debug2("channel %d: decode socks5", c->self);
989 p = buffer_ptr(&c->input);
990 if (p[0] != 0x05)
991 return -1;
992 have = buffer_len(&c->input);
993 if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
994 /* format: ver | nmethods | methods */
995 if (have < 2)
996 return 0;
997 nmethods = p[1];
998 if (have < nmethods + 2)
999 return 0;
1000 /* look for method: "NO AUTHENTICATION REQUIRED" */
1001 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1002 if (p[i] == SSH_SOCKS5_NOAUTH) {
1003 found = 1;
1004 break;
1005 }
1006 }
1007 if (!found) {
1008 error("channel %d: socks5 authentication methods not implemented",
1009 c->self);
1010 error("channel %d: forwarding failed: "
1011 "SSH_SOCKS5_NOAUTH method not found", c->self);
1012 return -1;
1013 }
1014 buffer_consume(&c->input, nmethods + 2);
1015 buffer_put_char(&c->output, 0x05); /* version */
1016 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1017 FD_SET(c->sock, writeset);
1018 c->flags |= SSH_SOCKS5_AUTHDONE;
1019 debug2("channel %d: socks5 auth done", c->self);
1020 return 0; /* need more */
1021 }
1022 debug2("channel %d: socks5 post auth", c->self);
1023 if (have < sizeof(s5_req)+1)
1024 return 0; /* need more */
1025 memcpy(&s5_req, p, sizeof(s5_req));
1026 if (s5_req.version != 0x05 ||
1027 s5_req.command != SSH_SOCKS5_CONNECT ||
1028 s5_req.reserved != 0x00) {
1029 error("channel %d: forwarding failed: "
1030 "only socks5 connect is supported", c->self);
1031 return -1;
1032 }
1033 switch (s5_req.atyp){
1034 case SSH_SOCKS5_IPV4:
1035 addrlen = 4;
1036 af = AF_INET;
1037 break;
1038 case SSH_SOCKS5_DOMAIN:
1039 addrlen = p[sizeof(s5_req)];
1040 af = -1;
1041 break;
1042 case SSH_SOCKS5_IPV6:
1043 addrlen = 16;
1044 af = AF_INET6;
1045 break;
1046 default:
1047 error("channel %d: forwarding failed: "
1048 "bad socks5 atyp %d", c->self, s5_req.atyp);
1049 return -1;
1050 }
1051 need = sizeof(s5_req) + addrlen + 2;
1052 if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1053 need++;
1054 if (have < need)
1055 return 0;
1056 buffer_consume(&c->input, sizeof(s5_req));
1057 if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1058 buffer_consume(&c->input, 1); /* host string length */
1059 buffer_get(&c->input, (char *)&dest_addr, addrlen);
1060 buffer_get(&c->input, (char *)&dest_port, 2);
1061 dest_addr[addrlen] = '\0';
1062 if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1063 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1064 else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1065 return -1;
1066 c->host_port = ntohs(dest_port);
1067
1068 debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1069 c->self, c->path, c->host_port, s5_req.command);
1070
1071 s5_rsp.version = 0x05;
1072 s5_rsp.command = SSH_SOCKS5_SUCCESS;
1073 s5_rsp.reserved = 0; /* ignored */
1074 s5_rsp.atyp = SSH_SOCKS5_IPV4;
1075 bzero(&bnd_addr, sizeof(bnd_addr));
1076 bnd_addr.s_addr = htonl(INADDR_ANY);
1077 dest_port = 0; /* ignored */
1078
1079 buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1080 buffer_append(&c->output, &bnd_addr, sizeof(struct in_addr));
1081 buffer_append(&c->output, &dest_port, sizeof(dest_port));
1082 return 1;
1083 }
1084
1085 /* dynamic port forwarding */
1086 static void
1087 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1088 {
1089 u_char *p;
1090 int have, ret;
1091
1092 have = buffer_len(&c->input);
1093 debug2("channel %d: pre_dynamic: have %d", c->self, have);
1094 /* buffer_dump(&c->input); */
1095 /* check if the fixed size part of the packet is in buffer. */
1096 if (have < 3) {
1097 /* need more */
1098 FD_SET(c->sock, readset);
1099 return;
1100 }
1101 /* try to guess the protocol */
1102 p = buffer_ptr(&c->input);
1103 switch (p[0]) {
1104 case 0x04:
1105 ret = channel_decode_socks4(c, readset, writeset);
1106 break;
1107 case 0x05:
1108 ret = channel_decode_socks5(c, readset, writeset);
1109 break;
1110 default:
1111 error("channel %d: forwarding failed: unknown socks "
1112 "version 0x%02X", c->self, p[0]);
1113 ret = -1;
1114 break;
1115 }
1116 if (ret < 0) {
1117 chan_mark_dead(c);
1118 } else if (ret == 0) {
1119 debug2("channel %d: pre_dynamic: need more", c->self);
1120 /* need more */
1121 FD_SET(c->sock, readset);
1122 } else {
1123 /* switch to the next state */
1124 c->type = SSH_CHANNEL_OPENING;
1125 port_open_helper(c, "direct-tcpip");
1126 }
1127 }
1128
1129 /* This is our fake X11 server socket. */
1130 static void
1131 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1132 {
1133 Channel *nc;
1134 struct sockaddr addr;
1135 int newsock;
1136 socklen_t addrlen;
1137 char buf[16384], *remote_ipaddr;
1138 int remote_port;
1139
1140 if (FD_ISSET(c->sock, readset)) {
1141 debug("X11 connection requested.");
1142 addrlen = sizeof(addr);
1143 newsock = accept(c->sock, &addr, &addrlen);
1144 if (c->single_connection) {
1145 debug("single_connection: closing X11 listener.");
1146 channel_close_fd(&c->sock);
1147 chan_mark_dead(c);
1148 }
1149 if (newsock < 0) {
1150 error("accept: %.100s", strerror(errno));
1151 return;
1152 }
1153 set_nodelay(newsock);
1154 remote_ipaddr = get_peer_ipaddr(newsock);
1155 remote_port = get_peer_port(newsock);
1156 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1157 remote_ipaddr, remote_port);
1158
1159 nc = channel_new("accepted x11 socket",
1160 SSH_CHANNEL_OPENING, newsock, newsock, -1,
1161 c->local_window_max, c->local_maxpacket,
1162 0, xstrdup(buf), 1);
1163 if (compat20) {
1164 packet_start(SSH2_MSG_CHANNEL_OPEN);
1165 packet_put_cstring("x11");
1166 packet_put_int(nc->self);
1167 packet_put_int(nc->local_window_max);
1168 packet_put_int(nc->local_maxpacket);
1169 /* originator ipaddr and port */
1170 packet_put_cstring(remote_ipaddr);
1171 if (datafellows & SSH_BUG_X11FWD) {
1172 debug("ssh2 x11 bug compat mode");
1173 } else {
1174 packet_put_int(remote_port);
1175 }
1176 packet_send();
1177 } else {
1178 packet_start(SSH_SMSG_X11_OPEN);
1179 packet_put_int(nc->self);
1180 if (packet_get_protocol_flags() &
1181 SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1182 packet_put_cstring(buf);
1183 packet_send();
1184 }
1185 xfree(remote_ipaddr);
1186 }
1187 }
1188
1189 static void
1190 port_open_helper(Channel *c, char *rtype)
1191 {
1192 int direct;
1193 char buf[1024];
1194 char *remote_ipaddr = get_peer_ipaddr(c->sock);
1195 u_short remote_port = get_peer_port(c->sock);
1196
1197 direct = (strcmp(rtype, "direct-tcpip") == 0);
1198
1199 snprintf(buf, sizeof buf,
1200 "%s: listening port %d for %.100s port %d, "
1201 "connect from %.200s port %d",
1202 rtype, c->listening_port, c->path, c->host_port,
1203 remote_ipaddr, remote_port);
1204
1205 xfree(c->remote_name);
1206 c->remote_name = xstrdup(buf);
1207
1208 if (compat20) {
1209 packet_start(SSH2_MSG_CHANNEL_OPEN);
1210 packet_put_cstring(rtype);
1211 packet_put_int(c->self);
1212 packet_put_int(c->local_window_max);
1213 packet_put_int(c->local_maxpacket);
1214 if (direct) {
1215 /* target host, port */
1216 packet_put_cstring(c->path);
1217 packet_put_int(c->host_port);
1218 } else {
1219 /* listen address, port */
1220 packet_put_cstring(c->path);
1221 packet_put_int(c->listening_port);
1222 }
1223 /* originator host and port */
1224 packet_put_cstring(remote_ipaddr);
1225 packet_put_int(remote_port);
1226 packet_send();
1227 } else {
1228 packet_start(SSH_MSG_PORT_OPEN);
1229 packet_put_int(c->self);
1230 packet_put_cstring(c->path);
1231 packet_put_int(c->host_port);
1232 if (packet_get_protocol_flags() &
1233 SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1234 packet_put_cstring(c->remote_name);
1235 packet_send();
1236 }
1237 xfree(remote_ipaddr);
1238 }
1239
1240 /*
1241 * This socket is listening for connections to a forwarded TCP/IP port.
1242 */
1243 static void
1244 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1245 {
1246 Channel *nc;
1247 struct sockaddr addr;
1248 int newsock, nextstate;
1249 socklen_t addrlen;
1250 char *rtype;
1251
1252 if (FD_ISSET(c->sock, readset)) {
1253 debug("Connection to port %d forwarding "
1254 "to %.100s port %d requested.",
1255 c->listening_port, c->path, c->host_port);
1256
1257 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1258 nextstate = SSH_CHANNEL_OPENING;
1259 rtype = "forwarded-tcpip";
1260 } else {
1261 if (c->host_port == 0) {
1262 nextstate = SSH_CHANNEL_DYNAMIC;
1263 rtype = "dynamic-tcpip";
1264 } else {
1265 nextstate = SSH_CHANNEL_OPENING;
1266 rtype = "direct-tcpip";
1267 }
1268 }
1269
1270 addrlen = sizeof(addr);
1271 newsock = accept(c->sock, &addr, &addrlen);
1272 if (newsock < 0) {
1273 error("accept: %.100s", strerror(errno));
1274 return;
1275 }
1276 set_nodelay(newsock);
1277 nc = channel_new(rtype,
1278 nextstate, newsock, newsock, -1,
1279 c->local_window_max, c->local_maxpacket,
1280 0, xstrdup(rtype), 1);
1281 nc->listening_port = c->listening_port;
1282 nc->host_port = c->host_port;
1283 strlcpy(nc->path, c->path, sizeof(nc->path));
1284
1285 if (nextstate != SSH_CHANNEL_DYNAMIC)
1286 port_open_helper(nc, rtype);
1287 }
1288 }
1289
1290 /*
1291 * This is the authentication agent socket listening for connections from
1292 * clients.
1293 */
1294 static void
1295 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1296 {
1297 Channel *nc;
1298 char *name;
1299 int newsock;
1300 struct sockaddr addr;
1301 socklen_t addrlen;
1302
1303 if (FD_ISSET(c->sock, readset)) {
1304 addrlen = sizeof(addr);
1305 newsock = accept(c->sock, &addr, &addrlen);
1306 if (newsock < 0) {
1307 error("accept from auth socket: %.100s", strerror(errno));
1308 return;
1309 }
1310 name = xstrdup("accepted auth socket");
1311 nc = channel_new("accepted auth socket",
1312 SSH_CHANNEL_OPENING, newsock, newsock, -1,
1313 c->local_window_max, c->local_maxpacket,
1314 0, name, 1);
1315 if (compat20) {
1316 packet_start(SSH2_MSG_CHANNEL_OPEN);
1317 packet_put_cstring("auth-agent@openssh.com");
1318 packet_put_int(nc->self);
1319 packet_put_int(c->local_window_max);
1320 packet_put_int(c->local_maxpacket);
1321 } else {
1322 packet_start(SSH_SMSG_AGENT_OPEN);
1323 packet_put_int(nc->self);
1324 }
1325 packet_send();
1326 }
1327 }
1328
1329 static void
1330 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1331 {
1332 int err = 0;
1333 socklen_t sz = sizeof(err);
1334
1335 if (FD_ISSET(c->sock, writeset)) {
1336 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1337 err = errno;
1338 error("getsockopt SO_ERROR failed");
1339 }
1340 if (err == 0) {
1341 debug("channel %d: connected", c->self);
1342 c->type = SSH_CHANNEL_OPEN;
1343 if (compat20) {
1344 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1345 packet_put_int(c->remote_id);
1346 packet_put_int(c->self);
1347 packet_put_int(c->local_window);
1348 packet_put_int(c->local_maxpacket);
1349 } else {
1350 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1351 packet_put_int(c->remote_id);
1352 packet_put_int(c->self);
1353 }
1354 } else {
1355 debug("channel %d: not connected: %s",
1356 c->self, strerror(err));
1357 if (compat20) {
1358 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1359 packet_put_int(c->remote_id);
1360 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1361 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1362 packet_put_utf8_cstring(strerror(err));
1363 packet_put_cstring("");
1364 }
1365 } else {
1366 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1367 packet_put_int(c->remote_id);
1368 }
1369 chan_mark_dead(c);
1370 }
1371 packet_send();
1372 }
1373 }
1374
1375 static int
1376 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1377 {
1378 char buf[CHAN_RBUF];
1379 int len;
1380
1381 if (c->rfd != -1 &&
1382 FD_ISSET(c->rfd, readset)) {
1383 len = read(c->rfd, buf, sizeof(buf));
1384 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1385 return 1;
1386 if (len <= 0) {
1387 debug("channel %d: read<=0 rfd %d len %d",
1388 c->self, c->rfd, len);
1389 if (c->type != SSH_CHANNEL_OPEN) {
1390 debug("channel %d: not open", c->self);
1391 chan_mark_dead(c);
1392 return -1;
1393 } else if (compat13) {
1394 buffer_clear(&c->output);
1395 c->type = SSH_CHANNEL_INPUT_DRAINING;
1396 debug("channel %d: input draining.", c->self);
1397 } else {
1398 chan_read_failed(c);
1399 }
1400 return -1;
1401 }
1402 if (c->input_filter != NULL) {
1403 if (c->input_filter(c, buf, len) == -1) {
1404 debug("channel %d: filter stops", c->self);
1405 chan_read_failed(c);
1406 }
1407 } else {
1408 buffer_append(&c->input, buf, len);
1409 }
1410 }
1411 return 1;
1412 }
1413 static int
1414 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1415 {
1416 struct termios tio;
1417 u_char *data;
1418 u_int dlen;
1419 int len;
1420
1421 /* Send buffered output data to the socket. */
1422 if (c->wfd != -1 &&
1423 FD_ISSET(c->wfd, writeset) &&
1424 buffer_len(&c->output) > 0) {
1425 data = buffer_ptr(&c->output);
1426 dlen = buffer_len(&c->output);
1427 #ifdef _AIX
1428 /* XXX: Later AIX versions can't push as much data to tty */
1429 if (compat20 && c->wfd_isatty && dlen > 8*1024)
1430 dlen = 8*1024;
1431 #endif
1432 len = write(c->wfd, data, dlen);
1433 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1434 return 1;
1435 if (len <= 0) {
1436 if (c->type != SSH_CHANNEL_OPEN) {
1437 debug("channel %d: not open", c->self);
1438 chan_mark_dead(c);
1439 return -1;
1440 } else if (compat13) {
1441 buffer_clear(&c->output);
1442 debug("channel %d: input draining.", c->self);
1443 c->type = SSH_CHANNEL_INPUT_DRAINING;
1444 } else {
1445 chan_write_failed(c);
1446 }
1447 return -1;
1448 }
1449 if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
1450 if (tcgetattr(c->wfd, &tio) == 0 &&
1451 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1452 /*
1453 * Simulate echo to reduce the impact of
1454 * traffic analysis. We need to match the
1455 * size of a SSH2_MSG_CHANNEL_DATA message
1456 * (4 byte channel id + data)
1457 */
1458 packet_send_ignore(4 + len);
1459 packet_send();
1460 }
1461 }
1462 buffer_consume(&c->output, len);
1463 if (compat20 && len > 0) {
1464 c->local_consumed += len;
1465 }
1466 }
1467 return 1;
1468 }
1469 static int
1470 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1471 {
1472 char buf[CHAN_RBUF];
1473 int len;
1474
1475 /** XXX handle drain efd, too */
1476 if (c->efd != -1) {
1477 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1478 FD_ISSET(c->efd, writeset) &&
1479 buffer_len(&c->extended) > 0) {
1480 len = write(c->efd, buffer_ptr(&c->extended),
1481 buffer_len(&c->extended));
1482 debug2("channel %d: written %d to efd %d",
1483 c->self, len, c->efd);
1484 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1485 return 1;
1486 if (len <= 0) {
1487 debug2("channel %d: closing write-efd %d",
1488 c->self, c->efd);
1489 channel_close_fd(&c->efd);
1490 } else {
1491 buffer_consume(&c->extended, len);
1492 c->local_consumed += len;
1493 }
1494 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1495 FD_ISSET(c->efd, readset)) {
1496 len = read(c->efd, buf, sizeof(buf));
1497 debug2("channel %d: read %d from efd %d",
1498 c->self, len, c->efd);
1499 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1500 return 1;
1501 if (len <= 0) {
1502 debug2("channel %d: closing read-efd %d",
1503 c->self, c->efd);
1504 channel_close_fd(&c->efd);
1505 } else {
1506 buffer_append(&c->extended, buf, len);
1507 }
1508 }
1509 }
1510 return 1;
1511 }
1512 static int
1513 channel_check_window(Channel *c)
1514 {
1515 if (c->type == SSH_CHANNEL_OPEN &&
1516 !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1517 c->local_window < c->local_window_max/2 &&
1518 c->local_consumed > 0) {
1519 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1520 packet_put_int(c->remote_id);
1521 packet_put_int(c->local_consumed);
1522 packet_send();
1523 debug2("channel %d: window %d sent adjust %d",
1524 c->self, c->local_window,
1525 c->local_consumed);
1526 c->local_window += c->local_consumed;
1527 c->local_consumed = 0;
1528 }
1529 return 1;
1530 }
1531
1532 static void
1533 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1534 {
1535 channel_handle_rfd(c, readset, writeset);
1536 channel_handle_wfd(c, readset, writeset);
1537 if (!compat20)
1538 return;
1539 channel_handle_efd(c, readset, writeset);
1540 channel_check_window(c);
1541 }
1542
1543 static void
1544 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1545 {
1546 int len;
1547
1548 /* Send buffered output data to the socket. */
1549 if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1550 len = write(c->sock, buffer_ptr(&c->output),
1551 buffer_len(&c->output));
1552 if (len <= 0)
1553 buffer_clear(&c->output);
1554 else
1555 buffer_consume(&c->output, len);
1556 }
1557 }
1558
1559 static void
1560 channel_handler_init_20(void)
1561 {
1562 channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
1563 channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
1564 channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
1565 channel_pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener;
1566 channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
1567 channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
1568 channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
1569 channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
1570
1571 channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
1572 channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
1573 channel_post[SSH_CHANNEL_RPORT_LISTENER] = &channel_post_port_listener;
1574 channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
1575 channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
1576 channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
1577 channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
1578 }
1579
1580 static void
1581 channel_handler_init_13(void)
1582 {
1583 channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_13;
1584 channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open_13;
1585 channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
1586 channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
1587 channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
1588 channel_pre[SSH_CHANNEL_INPUT_DRAINING] = &channel_pre_input_draining;
1589 channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_pre_output_draining;
1590 channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
1591 channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
1592
1593 channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
1594 channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
1595 channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
1596 channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
1597 channel_post[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_post_output_drain_13;
1598 channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
1599 channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
1600 }
1601
1602 static void
1603 channel_handler_init_15(void)
1604 {
1605 channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
1606 channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
1607 channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
1608 channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
1609 channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
1610 channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
1611 channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
1612
1613 channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
1614 channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
1615 channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
1616 channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
1617 channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
1618 channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
1619 }
1620
1621 static void
1622 channel_handler_init(void)
1623 {
1624 int i;
1625
1626 for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1627 channel_pre[i] = NULL;
1628 channel_post[i] = NULL;
1629 }
1630 if (compat20)
1631 channel_handler_init_20();
1632 else if (compat13)
1633 channel_handler_init_13();
1634 else
1635 channel_handler_init_15();
1636 }
1637
1638 /* gc dead channels */
1639 static void
1640 channel_garbage_collect(Channel *c)
1641 {
1642 if (c == NULL)
1643 return;
1644 if (c->detach_user != NULL) {
1645 if (!chan_is_dead(c, 0))
1646 return;
1647 debug("channel %d: gc: notify user", c->self);
1648 c->detach_user(c->self, NULL);
1649 /* if we still have a callback */
1650 if (c->detach_user != NULL)
1651 return;
1652 debug("channel %d: gc: user detached", c->self);
1653 }
1654 if (!c->wait_for_exit && !chan_is_dead(c, 1))
1655 return;
1656 debug("channel %d: garbage collecting", c->self);
1657 channel_free(c);
1658 }
1659
1660 static void
1661 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1662 {
1663 static int did_init = 0;
1664 int i, oalloc;
1665 Channel *c;
1666
1667 if (!did_init) {
1668 channel_handler_init();
1669 did_init = 1;
1670 }
1671 for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
1672 c = channels[i];
1673 if (c == NULL)
1674 continue;
1675 if (c->delayed) {
1676 if (ftab == channel_pre)
1677 c->delayed = 0;
1678 else
1679 continue;
1680 }
1681 if (ftab[c->type] != NULL)
1682 (*ftab[c->type])(c, readset, writeset);
1683 channel_garbage_collect(c);
1684 }
1685 }
1686
1687 /*
1688 * Allocate/update select bitmasks and add any bits relevant to channels in
1689 * select bitmasks.
1690 */
1691 void
1692 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1693 int *nallocp, int rekeying)
1694 {
1695 int n;
1696 u_int sz;
1697
1698 n = MAX(*maxfdp, channel_max_fd);
1699
1700 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1701 /* perhaps check sz < nalloc/2 and shrink? */
1702 if (*readsetp == NULL || sz > *nallocp) {
1703 *readsetp = xrealloc(*readsetp, sz);
1704 *writesetp = xrealloc(*writesetp, sz);
1705 *nallocp = sz;
1706 }
1707 *maxfdp = n;
1708 memset(*readsetp, 0, sz);
1709 memset(*writesetp, 0, sz);
1710
1711 if (!rekeying)
1712 channel_handler(channel_pre, *readsetp, *writesetp);
1713 }
1714
1715 /*
1716 * After select, perform any appropriate operations for channels which have
1717 * events pending.
1718 */
1719 void
1720 channel_after_select(fd_set * readset, fd_set * writeset)
1721 {
1722 channel_handler(channel_post, readset, writeset);
1723 }
1724
1725
1726 /* If there is data to send to the connection, enqueue some of it now. */
1727
1728 void
1729 channel_output_poll(void)
1730 {
1731 Channel *c;
1732 int i;
1733 u_int len;
1734
1735 for (i = 0; i < channels_alloc; i++) {
1736 c = channels[i];
1737 if (c == NULL)
1738 continue;
1739
1740 /*
1741 * We are only interested in channels that can have buffered
1742 * incoming data.
1743 */
1744 if (compat13) {
1745 if (c->type != SSH_CHANNEL_OPEN &&
1746 c->type != SSH_CHANNEL_INPUT_DRAINING)
1747 continue;
1748 } else {
1749 if (c->type != SSH_CHANNEL_OPEN)
1750 continue;
1751 }
1752 if (compat20 &&
1753 (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1754 /* XXX is this true? */
1755 debug3("channel %d: will not send data after close", c->self);
1756 continue;
1757 }
1758
1759 /* Get the amount of buffered data for this channel. */
1760 if ((c->istate == CHAN_INPUT_OPEN ||
1761 c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1762 (len = buffer_len(&c->input)) > 0) {
1763 /*
1764 * Send some data for the other side over the secure
1765 * connection.
1766 */
1767 if (compat20) {
1768 if (len > c->remote_window)
1769 len = c->remote_window;
1770 if (len > c->remote_maxpacket)
1771 len = c->remote_maxpacket;
1772 } else {
1773 if (packet_is_interactive()) {
1774 if (len > 1024)
1775 len = 512;
1776 } else {
1777 /* Keep the packets at reasonable size. */
1778 if (len > packet_get_maxsize()/2)
1779 len = packet_get_maxsize()/2;
1780 }
1781 }
1782 if (len > 0) {
1783 packet_start(compat20 ?
1784 SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1785 packet_put_int(c->remote_id);
1786 packet_put_string(buffer_ptr(&c->input), len);
1787 packet_send();
1788 buffer_consume(&c->input, len);
1789 c->remote_window -= len;
1790 }
1791 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1792 if (compat13)
1793 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1794 /*
1795 * input-buffer is empty and read-socket shutdown:
1796 * tell peer, that we will not send more data: send IEOF.
1797 * hack for extended data: delay EOF if EFD still in use.
1798 */
1799 if (CHANNEL_EFD_INPUT_ACTIVE(c))
1800 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1801 c->self, c->efd, buffer_len(&c->extended));
1802 else
1803 chan_ibuf_empty(c);
1804 }
1805 /* Send extended data, i.e. stderr */
1806 if (compat20 &&
1807 !(c->flags & CHAN_EOF_SENT) &&
1808 c->remote_window > 0 &&
1809 (len = buffer_len(&c->extended)) > 0 &&
1810 c->extended_usage == CHAN_EXTENDED_READ) {
1811 debug2("channel %d: rwin %u elen %u euse %d",
1812 c->self, c->remote_window, buffer_len(&c->extended),
1813 c->extended_usage);
1814 if (len > c->remote_window)
1815 len = c->remote_window;
1816 if (len > c->remote_maxpacket)
1817 len = c->remote_maxpacket;
1818 packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1819 packet_put_int(c->remote_id);
1820 packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1821 packet_put_string(buffer_ptr(&c->extended), len);
1822 packet_send();
1823 buffer_consume(&c->extended, len);
1824 c->remote_window -= len;
1825 debug2("channel %d: sent ext data %d", c->self, len);
1826 }
1827 }
1828 }
1829
1830
1831 /* -- protocol input */
1832
1833 void
1834 channel_input_data(int type, u_int32_t seq, void *ctxt)
1835 {
1836 int id;
1837 char *data;
1838 u_int data_len;
1839 Channel *c;
1840
1841 /* Get the channel number and verify it. */
1842 id = packet_get_int();
1843 c = channel_lookup(id);
1844 if (c == NULL)
1845 packet_disconnect("Received data for nonexistent channel %d.", id);
1846
1847 /* Ignore any data for non-open channels (might happen on close) */
1848 if (c->type != SSH_CHANNEL_OPEN &&
1849 c->type != SSH_CHANNEL_X11_OPEN)
1850 return;
1851
1852 /* same for protocol 1.5 if output end is no longer open */
1853 if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
1854 return;
1855
1856 /* Get the data. */
1857 data = packet_get_string(&data_len);
1858
1859 if (compat20) {
1860 if (data_len > c->local_maxpacket) {
1861 log("channel %d: rcvd big packet %d, maxpack %d",
1862 c->self, data_len, c->local_maxpacket);
1863 }
1864 if (data_len > c->local_window) {
1865 log("channel %d: rcvd too much data %d, win %d",
1866 c->self, data_len, c->local_window);
1867 xfree(data);
1868 return;
1869 }
1870 c->local_window -= data_len;
1871 }
1872 packet_check_eom();
1873 buffer_append(&c->output, data, data_len);
1874 xfree(data);
1875 }
1876
1877 void
1878 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
1879 {
1880 int id;
1881 char *data;
1882 u_int data_len, tcode;
1883 Channel *c;
1884
1885 /* Get the channel number and verify it. */
1886 id = packet_get_int();
1887 c = channel_lookup(id);
1888
1889 if (c == NULL)
1890 packet_disconnect("Received extended_data for bad channel %d.", id);
1891 if (c->type != SSH_CHANNEL_OPEN) {
1892 log("channel %d: ext data for non open", id);
1893 return;
1894 }
1895 if (c->flags & CHAN_EOF_RCVD) {
1896 if (datafellows & SSH_BUG_EXTEOF)
1897 debug("channel %d: accepting ext data after eof", id);
1898 else
1899 packet_disconnect("Received extended_data after EOF "
1900 "on channel %d.", id);
1901 }
1902 tcode = packet_get_int();
1903 if (c->efd == -1 ||
1904 c->extended_usage != CHAN_EXTENDED_WRITE ||
1905 tcode != SSH2_EXTENDED_DATA_STDERR) {
1906 log("channel %d: bad ext data", c->self);
1907 return;
1908 }
1909 data = packet_get_string(&data_len);
1910 packet_check_eom();
1911 if (data_len > c->local_window) {
1912 log("channel %d: rcvd too much extended_data %d, win %d",
1913 c->self, data_len, c->local_window);
1914 xfree(data);
1915 return;
1916 }
1917 debug2("channel %d: rcvd ext data %d", c->self, data_len);
1918 c->local_window -= data_len;
1919 buffer_append(&c->extended, data, data_len);
1920 xfree(data);
1921 }
1922
1923 void
1924 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
1925 {
1926 int id;
1927 Channel *c;
1928
1929 id = packet_get_int();
1930 packet_check_eom();
1931 c = channel_lookup(id);
1932 if (c == NULL)
1933 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1934 chan_rcvd_ieof(c);
1935
1936 /* XXX force input close */
1937 if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
1938 debug("channel %d: FORCE input drain", c->self);
1939 c->istate = CHAN_INPUT_WAIT_DRAIN;
1940 if (buffer_len(&c->input) == 0)
1941 chan_ibuf_empty(c);
1942 }
1943
1944 }
1945
1946 void
1947 channel_input_close(int type, u_int32_t seq, void *ctxt)
1948 {
1949 int id;
1950 Channel *c;
1951
1952 id = packet_get_int();
1953 packet_check_eom();
1954 c = channel_lookup(id);
1955 if (c == NULL)
1956 packet_disconnect("Received close for nonexistent channel %d.", id);
1957
1958 /*
1959 * Send a confirmation that we have closed the channel and no more
1960 * data is coming for it.
1961 */
1962 packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1963 packet_put_int(c->remote_id);
1964 packet_send();
1965
1966 /*
1967 * If the channel is in closed state, we have sent a close request,
1968 * and the other side will eventually respond with a confirmation.
1969 * Thus, we cannot free the channel here, because then there would be
1970 * no-one to receive the confirmation. The channel gets freed when
1971 * the confirmation arrives.
1972 */
1973 if (c->type != SSH_CHANNEL_CLOSED) {
1974 /*
1975 * Not a closed channel - mark it as draining, which will
1976 * cause it to be freed later.
1977 */
1978 buffer_clear(&c->input);
1979 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1980 }
1981 }
1982
1983 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1984 void
1985 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
1986 {
1987 int id = packet_get_int();
1988 Channel *c = channel_lookup(id);
1989
1990 packet_check_eom();
1991 if (c == NULL)
1992 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1993 chan_rcvd_oclose(c);
1994 }
1995
1996 void
1997 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
1998 {
1999 int id = packet_get_int();
2000 Channel *c = channel_lookup(id);
2001
2002 packet_check_eom();
2003 if (c == NULL)
2004 packet_disconnect("Received close confirmation for "
2005 "out-of-range channel %d.", id);
2006 if (c->type != SSH_CHANNEL_CLOSED)
2007 packet_disconnect("Received close confirmation for "
2008 "non-closed channel %d (type %d).", id, c->type);
2009 channel_free(c);
2010 }
2011
2012 void
2013 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2014 {
2015 int id, remote_id;
2016 Channel *c;
2017
2018 id = packet_get_int();
2019 c = channel_lookup(id);
2020
2021 if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2022 packet_disconnect("Received open confirmation for "
2023 "non-opening channel %d.", id);
2024 remote_id = packet_get_int();
2025 /* Record the remote channel number and mark that the channel is now open. */
2026 c->remote_id = remote_id;
2027 c->type = SSH_CHANNEL_OPEN;
2028
2029 if (compat20) {
2030 c->remote_window = packet_get_int();
2031 c->remote_maxpacket = packet_get_int();
2032 if (c->confirm) {
2033 debug2("callback start");
2034 c->confirm(c->self, NULL);
2035 debug2("callback done");
2036 }
2037 debug("channel %d: open confirm rwindow %u rmax %u", c->self,
2038 c->remote_window, c->remote_maxpacket);
2039 }
2040 packet_check_eom();
2041 }
2042
2043 static char *
2044 reason2txt(int reason)
2045 {
2046 switch (reason) {
2047 case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2048 return "administratively prohibited";
2049 case SSH2_OPEN_CONNECT_FAILED:
2050 return "connect failed";
2051 case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2052 return "unknown channel type";
2053 case SSH2_OPEN_RESOURCE_SHORTAGE:
2054 return "resource shortage";
2055 }
2056 return "unknown reason";
2057 }
2058
2059 void
2060 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2061 {
2062 int id, reason;
2063 char *msg = NULL, *lang = NULL;
2064 Channel *c;
2065
2066 id = packet_get_int();
2067 c = channel_lookup(id);
2068
2069 if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2070 packet_disconnect("Received open failure for "
2071 "non-opening channel %d.", id);
2072 if (compat20) {
2073 reason = packet_get_int();
2074 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2075 msg = packet_get_string(NULL);
2076 lang = packet_get_string(NULL);
2077 }
2078 log("channel %d: open failed: %s%s%s", id,
2079 reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2080 if (msg != NULL)
2081 xfree(msg);
2082 if (lang != NULL)
2083 xfree(lang);
2084 }
2085 packet_check_eom();
2086 /* Free the channel. This will also close the socket. */
2087 channel_free(c);
2088 }
2089
2090 void
2091 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2092 {
2093 Channel *c;
2094 int id;
2095 u_int adjust;
2096
2097 if (!compat20)
2098 return;
2099
2100 /* Get the channel number and verify it. */
2101 id = packet_get_int();
2102 c = channel_lookup(id);
2103
2104 if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
2105 log("Received window adjust for "
2106 "non-open channel %d.", id);
2107 return;
2108 }
2109 adjust = packet_get_int();
2110 packet_check_eom();
2111 debug2("channel %d: rcvd adjust %u", id, adjust);
2112 c->remote_window += adjust;
2113 }
2114
2115 void
2116 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2117 {
2118 Channel *c = NULL;
2119 u_short host_port;
2120 char *host, *originator_string;
2121 int remote_id, sock = -1;
2122
2123 remote_id = packet_get_int();
2124 host = packet_get_string(NULL);
2125 host_port = packet_get_int();
2126
2127 if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2128 originator_string = packet_get_string(NULL);
2129 } else {
2130 originator_string = xstrdup("unknown (remote did not supply name)");
2131 }
2132 packet_check_eom();
2133 sock = channel_connect_to(host, host_port);
2134 if (sock != -1) {
2135 c = channel_new("connected socket",
2136 SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2137 originator_string, 1);
2138 c->remote_id = remote_id;
2139 }
2140 if (c == NULL) {
2141 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2142 packet_put_int(remote_id);
2143 packet_send();
2144 }
2145 xfree(host);
2146 }
2147
2148
2149 /* -- tcp forwarding */
2150
2151 void
2152 channel_set_af(int af)
2153 {
2154 IPv4or6 = af;
2155 }
2156
2157 static int
2158 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2159 const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2160 {
2161 Channel *c;
2162 int sock, r, is_client, on = 1, wildcard = 0, success = 0;
2163 struct addrinfo hints, *ai, *aitop;
2164 const char *host, *addr;
2165 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2166
2167 host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2168 listen_addr : host_to_connect;
2169 is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2170
2171 if (host == NULL) {
2172 error("No forward host name.");
2173 return 0;
2174 }
2175 if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2176 error("Forward host name too long.");
2177 return 0;
2178 }
2179
2180 /*
2181 * Determine whether or not a port forward listens to loopback,
2182 * specified address or wildcard. On the client, a specified bind
2183 * address will always override gateway_ports. On the server, a
2184 * gateway_ports of 1 (``yes'') will override the client's
2185 * specification and force a wildcard bind, whereas a value of 2
2186 * (``clientspecified'') will bind to whatever address the client
2187 * asked for.
2188 *
2189 * Special-case listen_addrs are:
2190 *
2191 * "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2192 * "" (empty string), "*" -> wildcard v4/v6
2193 * "localhost" -> loopback v4/v6
2194 */
2195 addr = NULL;
2196 if (listen_addr == NULL) {
2197 /* No address specified: default to gateway_ports setting */
2198 if (gateway_ports)
2199 wildcard = 1;
2200 } else if (gateway_ports || is_client) {
2201 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2202 strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2203 *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2204 (!is_client && gateway_ports == 1))
2205 wildcard = 1;
2206 else if (strcmp(listen_addr, "localhost") != 0)
2207 addr = listen_addr;
2208 }
2209
2210 debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2211 type, wildcard, (addr == NULL) ? "NULL" : addr);
2212
2213 /*
2214 * getaddrinfo returns a loopback address if the hostname is
2215 * set to NULL and hints.ai_flags is not AI_PASSIVE
2216 */
2217 memset(&hints, 0, sizeof(hints));
2218 hints.ai_family = IPv4or6;
2219 hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2220 hints.ai_socktype = SOCK_STREAM;
2221 snprintf(strport, sizeof strport, "%d", listen_port);
2222 if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2223 if (addr == NULL) {
2224 /* This really shouldn't happen */
2225 packet_disconnect("getaddrinfo: fatal error: %s",
2226 gai_strerror(r));
2227 } else {
2228 error("channel_setup_fwd_listener: "
2229 "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2230 }
2231 return 0;
2232 }
2233
2234 for (ai = aitop; ai; ai = ai->ai_next) {
2235 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2236 continue;
2237 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2238 strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2239 error("channel_setup_fwd_listener: getnameinfo failed");
2240 continue;
2241 }
2242 /* Create a port to listen for the host. */
2243 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2244 if (sock < 0) {
2245 /* this is no error since kernel may not support ipv6 */
2246 verbose("socket: %.100s", strerror(errno));
2247 continue;
2248 }
2249 /*
2250 * Set socket options.
2251 * Allow local port reuse in TIME_WAIT.
2252 */
2253 if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
2254 sizeof(on)) == -1)
2255 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
2256
2257 debug("Local forwarding listening on %s port %s.", ntop, strport);
2258
2259 /* Bind the socket to the address. */
2260 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2261 /* address can be in use ipv6 address is already bound */
2262 if (!ai->ai_next)
2263 error("bind: %.100s", strerror(errno));
2264 else
2265 verbose("bind: %.100s", strerror(errno));
2266
2267 close(sock);
2268 continue;
2269 }
2270 /* Start listening for connections on the socket. */
2271 if (listen(sock, 5) < 0) {
2272 error("listen: %.100s", strerror(errno));
2273 close(sock);
2274 continue;
2275 }
2276 /* Allocate a channel number for the socket. */
2277 c = channel_new("port listener", type, sock, sock, -1,
2278 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2279 0, xstrdup("port listener"), 1);
2280 strlcpy(c->path, host, sizeof(c->path));
2281 c->host_port = port_to_connect;
2282 c->listening_port = listen_port;
2283 success = 1;
2284 }
2285 if (success == 0)
2286 error("channel_setup_fwd_listener: cannot listen to port: %d",
2287 listen_port);
2288 freeaddrinfo(aitop);
2289 return success;
2290 }
2291
2292 int
2293 channel_cancel_rport_listener(const char *host, u_short port)
2294 {
2295 u_int i;
2296 int found = 0;
2297
2298 for (i = 0; i < channels_alloc; i++) {
2299 Channel *c = channels[i];
2300
2301 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2302 strncmp(c->path, host, sizeof(c->path)) == 0 &&
2303 c->listening_port == port) {
2304 debug2("%s: close channel %d", __func__, i);
2305 channel_free(c);
2306 found = 1;
2307 }
2308 }
2309
2310 return (found);
2311 }
2312
2313 /* protocol local port fwd, used by ssh (and sshd in v1) */
2314 int
2315 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2316 const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2317 {
2318 return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2319 listen_host, listen_port, host_to_connect, port_to_connect,
2320 gateway_ports);
2321 }
2322
2323 /* protocol v2 remote port fwd, used by sshd */
2324 int
2325 channel_setup_remote_fwd_listener(const char *listen_address,
2326 u_short listen_port, int gateway_ports)
2327 {
2328 return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2329 listen_address, listen_port, NULL, 0, gateway_ports);
2330 }
2331
2332 /*
2333 * Initiate forwarding of connections to port "port" on remote host through
2334 * the secure channel to host:port from local side.
2335 */
2336
2337 int
2338 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2339 const char *host_to_connect, u_short port_to_connect)
2340 {
2341 int type, success = 0;
2342
2343 /* Record locally that connection to this host/port is permitted. */
2344 if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2345 fatal("channel_request_remote_forwarding: too many forwards");
2346
2347 if (listen_host != NULL &&
2348 strlen(listen_host) > SSH_CHANNEL_PATH_LEN - 1) {
2349 error("Binding address too long.");
2350 return -1;
2351 }
2352
2353 /* Send the forward request to the remote side. */
2354 if (compat20) {
2355 const char *address_to_bind;
2356 if (listen_host == NULL) {
2357 if (datafellows & SSH_BUG_RFWD_ADDR)
2358 address_to_bind = "127.0.0.1";
2359 else
2360 address_to_bind = "localhost";
2361 } else if (*listen_host == '\0' ||
2362 strcmp(listen_host, "*") == 0) {
2363 if (datafellows & SSH_BUG_RFWD_ADDR)
2364 address_to_bind = "0.0.0.0";
2365 else
2366 address_to_bind = "";
2367 } else
2368 address_to_bind = listen_host;
2369
2370 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2371 packet_put_cstring("tcpip-forward");
2372 packet_put_char(1); /* boolean: want reply */
2373 packet_put_cstring(address_to_bind);
2374 packet_put_int(listen_port);
2375 packet_send();
2376 packet_write_wait();
2377 /* Assume that server accepts the request */
2378 success = 1;
2379 } else {
2380 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2381 packet_put_int(listen_port);
2382 packet_put_cstring(host_to_connect);
2383 packet_put_int(port_to_connect);
2384 packet_send();
2385 packet_write_wait();
2386
2387 /* Wait for response from the remote side. */
2388 type = packet_read();
2389 switch (type) {
2390 case SSH_SMSG_SUCCESS:
2391 success = 1;
2392 break;
2393 case SSH_SMSG_FAILURE:
2394 log("Warning: Server denied remote port forwarding.");
2395 break;
2396 default:
2397 /* Unknown packet */
2398 packet_disconnect("Protocol error for port forward request:"
2399 "received packet type %d.", type);
2400 }
2401 }
2402 if (success) {
2403 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2404 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2405 permitted_opens[num_permitted_opens].listen_port = listen_port;
2406 num_permitted_opens++;
2407 }
2408 return (success ? 0 : -1);
2409 }
2410
2411 /*
2412 * Request cancellation of remote forwarding of connection host:port from
2413 * local side.
2414 */
2415 void
2416 channel_request_rforward_cancel(const char *host, u_short port)
2417 {
2418 int i;
2419
2420 if (!compat20)
2421 return;
2422
2423 for (i = 0; i < num_permitted_opens; i++) {
2424 if (permitted_opens[i].host_to_connect != NULL &&
2425 permitted_opens[i].listen_port == port)
2426 break;
2427 }
2428 if (i >= num_permitted_opens) {
2429 debug("%s: requested forward not found", __func__);
2430 return;
2431 }
2432 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2433 packet_put_cstring("cancel-tcpip-forward");
2434 packet_put_char(0);
2435 packet_put_cstring(host == NULL ? "" : host);
2436 packet_put_int(port);
2437 packet_send();
2438
2439 permitted_opens[i].listen_port = 0;
2440 permitted_opens[i].port_to_connect = 0;
2441 xfree(permitted_opens[i].host_to_connect);
2442 permitted_opens[i].host_to_connect = NULL;
2443 }
2444
2445 /*
2446 * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
2447 * listening for the port, and sends back a success reply (or disconnect
2448 * message if there was an error). This never returns if there was an error.
2449 */
2450
2451 void
2452 channel_input_port_forward_request(int is_root, int gateway_ports)
2453 {
2454 u_short port, host_port;
2455 char *hostname;
2456
2457 /* Get arguments from the packet. */
2458 port = packet_get_int();
2459 hostname = packet_get_string(NULL);
2460 host_port = packet_get_int();
2461
2462 #ifndef HAVE_CYGWIN
2463 /*
2464 * Check that an unprivileged user is not trying to forward a
2465 * privileged port.
2466 */
2467 if (port < IPPORT_RESERVED && !is_root)
2468 packet_disconnect("Requested forwarding of port %d but user is not root.",
2469 port);
2470 #endif
2471 /* Initiate forwarding */
2472 channel_setup_local_fwd_listener(NULL, port, hostname,
2473 host_port, gateway_ports);
2474
2475 /* Free the argument string. */
2476 xfree(hostname);
2477 }
2478
2479 /*
2480 * Permits opening to any host/port if permitted_opens[] is empty. This is
2481 * usually called by the server, because the user could connect to any port
2482 * anyway, and the server has no way to know but to trust the client anyway.
2483 */
2484 void
2485 channel_permit_all_opens(void)
2486 {
2487 if (num_permitted_opens == 0)
2488 all_opens_permitted = 1;
2489 }
2490
2491 void
2492 channel_add_permitted_opens(char *host, int port)
2493 {
2494 if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2495 fatal("channel_add_permitted_opens: too many forwards");
2496 debug("allow port forwarding to host %s port %d", host, port);
2497
2498 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2499 permitted_opens[num_permitted_opens].port_to_connect = port;
2500 num_permitted_opens++;
2501
2502 all_opens_permitted = 0;
2503 }
2504
2505 void
2506 channel_clear_permitted_opens(void)
2507 {
2508 int i;
2509
2510 for (i = 0; i < num_permitted_opens; i++)
2511 xfree(permitted_opens[i].host_to_connect);
2512 num_permitted_opens = 0;
2513 }
2514
2515
2516 /* return socket to remote host, port */
2517 static int
2518 connect_to(const char *host, u_short port)
2519 {
2520 struct addrinfo hints, *ai, *aitop;
2521 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2522 int gaierr;
2523 int sock = -1;
2524
2525 memset(&hints, 0, sizeof(hints));
2526 hints.ai_family = IPv4or6;
2527 hints.ai_socktype = SOCK_STREAM;
2528 snprintf(strport, sizeof strport, "%d", port);
2529 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2530 error("connect_to %.100s: unknown host (%s)", host,
2531 gai_strerror(gaierr));
2532 return -1;
2533 }
2534 for (ai = aitop; ai; ai = ai->ai_next) {
2535 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2536 continue;
2537 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2538 strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2539 error("connect_to: getnameinfo failed");
2540 continue;
2541 }
2542 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2543 if (sock < 0) {
2544 error("socket: %.100s", strerror(errno));
2545 continue;
2546 }
2547 if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
2548 fatal("connect_to: F_SETFL: %s", strerror(errno));
2549 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2550 errno != EINPROGRESS) {
2551 error("connect_to %.100s port %s: %.100s", ntop, strport,
2552 strerror(errno));
2553 close(sock);
2554 continue; /* fail -- try next */
2555 }
2556 break; /* success */
2557
2558 }
2559 freeaddrinfo(aitop);
2560 if (!ai) {
2561 error("connect_to %.100s port %d: failed.", host, port);
2562 return -1;
2563 }
2564 /* success */
2565 set_nodelay(sock);
2566 return sock;
2567 }
2568
2569 int
2570 channel_connect_by_listen_address(u_short listen_port)
2571 {
2572 int i;
2573
2574 for (i = 0; i < num_permitted_opens; i++)
2575 if (permitted_opens[i].listen_port == listen_port)
2576 return connect_to(
2577 permitted_opens[i].host_to_connect,
2578 permitted_opens[i].port_to_connect);
2579 error("WARNING: Server requests forwarding for unknown listen_port %d",
2580 listen_port);
2581 return -1;
2582 }
2583
2584 /* Check if connecting to that port is permitted and connect. */
2585 int
2586 channel_connect_to(const char *host, u_short port)
2587 {
2588 int i, permit;
2589
2590 permit = all_opens_permitted;
2591 if (!permit) {
2592 for (i = 0; i < num_permitted_opens; i++)
2593 if (permitted_opens[i].port_to_connect == port &&
2594 strcmp(permitted_opens[i].host_to_connect, host) == 0)
2595 permit = 1;
2596
2597 }
2598 if (!permit) {
2599 log("Received request to connect to host %.100s port %d, "
2600 "but the request was denied.", host, port);
2601 return -1;
2602 }
2603 return connect_to(host, port);
2604 }
2605
2606 /* -- X11 forwarding */
2607
2608 /*
2609 * Creates an internet domain socket for listening for X11 connections.
2610 * Returns 0 and a suitable display number for the DISPLAY variable
2611 * stored in display_numberp , or -1 if an error occurs.
2612 */
2613 int
2614 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2615 int single_connection, u_int *display_numberp)
2616 {
2617 Channel *nc = NULL;
2618 int display_number, sock;
2619 u_short port;
2620 struct addrinfo hints, *ai, *aitop;
2621 char strport[NI_MAXSERV];
2622 int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2623
2624 for (display_number = x11_display_offset;
2625 display_number < MAX_DISPLAYS;
2626 display_number++) {
2627 port = 6000 + display_number;
2628 memset(&hints, 0, sizeof(hints));
2629 hints.ai_family = IPv4or6;
2630 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2631 hints.ai_socktype = SOCK_STREAM;
2632 snprintf(strport, sizeof strport, "%d", port);
2633 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2634 error("getaddrinfo: %.100s", gai_strerror(gaierr));
2635 return -1;
2636 }
2637 for (ai = aitop; ai; ai = ai->ai_next) {
2638 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2639 continue;
2640 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2641 if (sock < 0) {
2642 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2643 error("socket: %.100s", strerror(errno));
2644 freeaddrinfo(aitop);
2645 for (n = 0; n < num_socks; n++)
2646 close(socks[n]);
2647 return -1;
2648 } else {
2649 debug("x11_create_display_inet: Socket family %d not supported",
2650 ai->ai_family);
2651 continue;
2652 }
2653 }
2654 #ifdef IPV6_V6ONLY
2655 if (ai->ai_family == AF_INET6) {
2656 int on = 1;
2657 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2658 error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2659 }
2660 #endif
2661 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2662 /*
2663 * If bind() fails with EADDRNOTAVAIL, we
2664 * should not break immediately but rather
2665 * try the next address available.
2666 */
2667 if (errno == EADDRNOTAVAIL) {
2668 close(sock);
2669 continue;
2670 }
2671
2672 debug("bind port %d: %.100s; skipping this port", port,
2673 strerror(errno));
2674 close(sock);
2675
2676 for (n = 0; n < num_socks; n++) {
2677 close(socks[n]);
2678 }
2679 num_socks = 0;
2680 break;
2681 }
2682 socks[num_socks++] = sock;
2683 #ifndef DONT_TRY_OTHER_AF
2684 if (num_socks == NUM_SOCKS)
2685 break;
2686 #else
2687 if (x11_use_localhost) {
2688 if (num_socks == NUM_SOCKS)
2689 break;
2690 } else {
2691 break;
2692 }
2693 #endif
2694 }
2695 freeaddrinfo(aitop);
2696 if (num_socks > 0)
2697 break;
2698 }
2699 if (display_number >= MAX_DISPLAYS) {
2700 error("Failed to allocate internet-domain X11 display socket.");
2701 return -1;
2702 }
2703 /* Start listening for connections on the socket. */
2704 for (n = 0; n < num_socks; n++) {
2705 sock = socks[n];
2706 if (listen(sock, 5) < 0) {
2707 int i;
2708 error("listen: %.100s", strerror(errno));
2709 for (i = 0; i < num_socks; i++)
2710 close(socks[i]);
2711 return -1;
2712 }
2713 }
2714
2715 /* Allocate a channel for each socket. */
2716 for (n = 0; n < num_socks; n++) {
2717 sock = socks[n];
2718 nc = channel_new("x11 listener",
2719 SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2720 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2721 0, xstrdup("X11 inet listener"), 1);
2722 nc->single_connection = single_connection;
2723 }
2724
2725 /* Return the display number for the DISPLAY environment variable. */
2726 *display_numberp = display_number;
2727 return (0);
2728 }
2729
2730 static int
2731 connect_local_xsocket(u_int dnr)
2732 {
2733 int sock;
2734 struct sockaddr_un addr;
2735
2736 sock = socket(AF_UNIX, SOCK_STREAM, 0);
2737 if (sock < 0)
2738 error("socket: %.100s", strerror(errno));
2739 memset(&addr, 0, sizeof(addr));
2740 addr.sun_family = AF_UNIX;
2741 snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2742 if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2743 return sock;
2744 close(sock);
2745 error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2746 return -1;
2747 }
2748
2749 int
2750 x11_connect_display(void)
2751 {
2752 int display_number, sock = 0;
2753 const char *display;
2754 char buf[1024], *cp;
2755 struct addrinfo hints, *ai, *aitop;
2756 char strport[NI_MAXSERV];
2757 int gaierr;
2758
2759 /* Try to open a socket for the local X server. */
2760 display = getenv("DISPLAY");
2761 if (!display) {
2762 error("DISPLAY not set.");
2763 return -1;
2764 }
2765 /*
2766 * Now we decode the value of the DISPLAY variable and make a
2767 * connection to the real X server.
2768 */
2769
2770 /*
2771 * Check if it is a unix domain socket. Unix domain displays are in
2772 * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2773 */
2774 if (strncmp(display, "unix:", 5) == 0 ||
2775 display[0] == ':') {
2776 /* Connect to the unix domain socket. */
2777 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2778 error("Could not parse display number from DISPLAY: %.100s",
2779 display);
2780 return -1;
2781 }
2782 /* Create a socket. */
2783 sock = connect_local_xsocket(display_number);
2784 if (sock < 0)
2785 return -1;
2786
2787 /* OK, we now have a connection to the display. */
2788 return sock;
2789 }
2790 /*
2791 * Connect to an inet socket. The DISPLAY value is supposedly
2792 * hostname:d[.s], where hostname may also be numeric IP address.
2793 */
2794 strlcpy(buf, display, sizeof(buf));
2795 cp = strchr(buf, ':');
2796 if (!cp) {
2797 error("Could not find ':' in DISPLAY: %.100s", display);
2798 return -1;
2799 }
2800 *cp = 0;
2801 /* buf now contains the host name. But first we parse the display number. */
2802 if (sscanf(cp + 1, "%d", &display_number) != 1) {
2803 error("Could not parse display number from DISPLAY: %.100s",
2804 display);
2805 return -1;
2806 }
2807
2808 /* Look up the host address */
2809 memset(&hints, 0, sizeof(hints));
2810 hints.ai_family = IPv4or6;
2811 hints.ai_socktype = SOCK_STREAM;
2812 snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2813 if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2814 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2815 return -1;
2816 }
2817 for (ai = aitop; ai; ai = ai->ai_next) {
2818 /* Create a socket. */
2819 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2820 if (sock < 0) {
2821 debug("socket: %.100s", strerror(errno));
2822 continue;
2823 }
2824 /* Connect it to the display. */
2825 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2826 debug("connect %.100s port %d: %.100s", buf,
2827 6000 + display_number, strerror(errno));
2828 close(sock);
2829 continue;
2830 }
2831 /* Success */
2832 break;
2833 }
2834 freeaddrinfo(aitop);
2835 if (!ai) {
2836 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2837 strerror(errno));
2838 return -1;
2839 }
2840 set_nodelay(sock);
2841 return sock;
2842 }
2843
2844 /*
2845 * This is called when SSH_SMSG_X11_OPEN is received. The packet contains
2846 * the remote channel number. We should do whatever we want, and respond
2847 * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2848 */
2849
2850 void
2851 x11_input_open(int type, u_int32_t seq, void *ctxt)
2852 {
2853 Channel *c = NULL;
2854 int remote_id, sock = 0;
2855 char *remote_host;
2856
2857 debug("Received X11 open request.");
2858
2859 remote_id = packet_get_int();
2860
2861 if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2862 remote_host = packet_get_string(NULL);
2863 } else {
2864 remote_host = xstrdup("unknown (remote did not supply name)");
2865 }
2866 packet_check_eom();
2867
2868 /* Obtain a connection to the real X display. */
2869 sock = x11_connect_display();
2870 if (sock != -1) {
2871 /* Allocate a channel for this connection. */
2872 c = channel_new("connected x11 socket",
2873 SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
2874 remote_host, 1);
2875 c->remote_id = remote_id;
2876 c->force_drain = 1;
2877 }
2878 if (c == NULL) {
2879 /* Send refusal to the remote host. */
2880 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2881 packet_put_int(remote_id);
2882 } else {
2883 /* Send a confirmation to the remote host. */
2884 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2885 packet_put_int(remote_id);
2886 packet_put_int(c->self);
2887 }
2888 packet_send();
2889 }
2890
2891 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2892 void
2893 deny_input_open(int type, u_int32_t seq, void *ctxt)
2894 {
2895 int rchan = packet_get_int();
2896
2897 switch (type) {
2898 case SSH_SMSG_AGENT_OPEN:
2899 error("Warning: ssh server tried agent forwarding.");
2900 break;
2901 case SSH_SMSG_X11_OPEN:
2902 error("Warning: ssh server tried X11 forwarding.");
2903 break;
2904 default:
2905 error("deny_input_open: type %d", type);
2906 break;
2907 }
2908 error("Warning: this is probably a break in attempt by a malicious server.");
2909 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2910 packet_put_int(rchan);
2911 packet_send();
2912 }
2913
2914 /*
2915 * Requests forwarding of X11 connections, generates fake authentication
2916 * data, and enables authentication spoofing.
2917 * This should be called in the client only.
2918 */
2919 void
2920 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
2921 const char *proto, const char *data)
2922 {
2923 u_int data_len = (u_int) strlen(data) / 2;
2924 u_int i, value;
2925 char *new_data;
2926 int screen_number;
2927 const char *cp;
2928 u_int32_t rand = 0;
2929
2930 cp = disp;
2931 if (disp)
2932 cp = strchr(disp, ':');
2933 if (cp)
2934 cp = strchr(cp, '.');
2935 if (cp)
2936 screen_number = atoi(cp + 1);
2937 else
2938 screen_number = 0;
2939
2940 /* Save protocol name. */
2941 x11_saved_proto = xstrdup(proto);
2942
2943 /*
2944 * Extract real authentication data and generate fake data of the
2945 * same length.
2946 */
2947 x11_saved_data = xmalloc(data_len);
2948 x11_fake_data = xmalloc(data_len);
2949 for (i = 0; i < data_len; i++) {
2950 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2951 fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2952 if (i % 4 == 0)
2953 rand = arc4random();
2954 x11_saved_data[i] = value;
2955 x11_fake_data[i] = rand & 0xff;
2956 rand >>= 8;
2957 }
2958 x11_saved_data_len = data_len;
2959 x11_fake_data_len = data_len;
2960
2961 /* Convert the fake data into hex. */
2962 new_data = tohex(x11_fake_data, data_len);
2963
2964 /* Send the request packet. */
2965 if (compat20) {
2966 channel_request_start(client_session_id, "x11-req", 0);
2967 packet_put_char(0); /* XXX bool single connection */
2968 } else {
2969 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2970 }
2971 packet_put_cstring(proto);
2972 packet_put_cstring(new_data);
2973 packet_put_int(screen_number);
2974 packet_send();
2975 packet_write_wait();
2976 xfree(new_data);
2977 }
2978
2979
2980 /* -- agent forwarding */
2981
2982 /* Sends a message to the server to request authentication fd forwarding. */
2983
2984 void
2985 auth_request_forwarding(void)
2986 {
2987 packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2988 packet_send();
2989 packet_write_wait();
2990 }
2991
2992 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
2993
2994 void
2995 auth_input_open_request(int type, u_int32_t seq, void *ctxt)
2996 {
2997 Channel *c = NULL;
2998 int remote_id, sock;
2999 char *name;
3000
3001 /* Read the remote channel number from the message. */
3002 remote_id = packet_get_int();
3003 packet_check_eom();
3004
3005 /*
3006 * Get a connection to the local authentication agent (this may again
3007 * get forwarded).
3008 */
3009 sock = ssh_get_authentication_socket();
3010
3011 /*
3012 * If we could not connect the agent, send an error message back to
3013 * the server. This should never happen unless the agent dies,
3014 * because authentication forwarding is only enabled if we have an
3015 * agent.
3016 */
3017 if (sock >= 0) {
3018 name = xstrdup("authentication agent connection");
3019 c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
3020 -1, 0, 0, 0, name, 1);
3021 c->remote_id = remote_id;
3022 c->force_drain = 1;
3023 }
3024 if (c == NULL) {
3025 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3026 packet_put_int(remote_id);
3027 } else {
3028 /* Send a confirmation to the remote host. */
3029 debug("Forwarding authentication connection.");
3030 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3031 packet_put_int(remote_id);
3032 packet_put_int(c->self);
3033 }
3034 packet_send();
3035 }