1/*
2 *
3 * channels.c
4 *
5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
6 *
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 * All rights reserved
9 *
10 * Created: Fri Mar 24 16:35:24 1995 ylo
11 *
12 * This file contains functions for generic socket connection forwarding.
13 * There is also code for initiating connection forwarding for X11 connections,
14 * arbitrary tcp/ip connections, and the authentication agent connection.
15 *
16 */
17
18#include "includes.h"
|
19RCSID("$Id: channels.c,v 1.38 2000/01/24 20:37:29 markus Exp $");
|
| 19RCSID("$Id: channels.c,v 1.39 2000/03/16 20:56:14 markus Exp $"); |
20
21#include "ssh.h"
22#include "packet.h"
23#include "xmalloc.h"
24#include "buffer.h"
25#include "authfd.h"
26#include "uidswap.h"
27#include "readconf.h"
28#include "servconf.h"
29
30#include "channels.h"
31#include "nchan.h"
32#include "compat.h"
33
34/* Maximum number of fake X11 displays to try. */
35#define MAX_DISPLAYS 1000
36
37/* Max len of agent socket */
38#define MAX_SOCKET_NAME 100
39
40/*
41 * Pointer to an array containing all allocated channels. The array is
42 * dynamically extended as needed.
43 */
44static Channel *channels = NULL;
45
46/*
47 * Size of the channel array. All slots of the array must always be
48 * initialized (at least the type field); unused slots are marked with type
49 * SSH_CHANNEL_FREE.
50 */
51static int channels_alloc = 0;
52
53/*
54 * Maximum file descriptor value used in any of the channels. This is
55 * updated in channel_allocate.
56 */
57static int channel_max_fd_value = 0;
58
59/* Name and directory of socket for authentication agent forwarding. */
60static char *channel_forwarded_auth_socket_name = NULL;
61static char *channel_forwarded_auth_socket_dir = NULL;
62
63/* Saved X11 authentication protocol name. */
64char *x11_saved_proto = NULL;
65
66/* Saved X11 authentication data. This is the real data. */
67char *x11_saved_data = NULL;
68unsigned int x11_saved_data_len = 0;
69
70/*
71 * Fake X11 authentication data. This is what the server will be sending us;
72 * we should replace any occurrences of this by the real data.
73 */
74char *x11_fake_data = NULL;
75unsigned int x11_fake_data_len;
76
77/*
78 * Data structure for storing which hosts are permitted for forward requests.
79 * The local sides of any remote forwards are stored in this array to prevent
80 * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
81 * network (which might be behind a firewall).
82 */
83typedef struct {
84 char *host; /* Host name. */
85 u_short port; /* Port number. */
86} ForwardPermission;
87
88/* List of all permitted host/port pairs to connect. */
89static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
90/* Number of permitted host/port pairs in the array. */
91static int num_permitted_opens = 0;
92/*
93 * If this is true, all opens are permitted. This is the case on the server
94 * on which we have to trust the client anyway, and the user could do
95 * anything after logging in anyway.
96 */
97static int all_opens_permitted = 0;
98
99/* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
100static int have_hostname_in_open = 0;
101
102/* Sets specific protocol options. */
103
104void
105channel_set_options(int hostname_in_open)
106{
107 have_hostname_in_open = hostname_in_open;
108}
109
110/*
111 * Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually
112 * called by the server, because the user could connect to any port anyway,
113 * and the server has no way to know but to trust the client anyway.
114 */
115
116void
117channel_permit_all_opens()
118{
119 all_opens_permitted = 1;
120}
121
122/*
123 * Allocate a new channel object and set its type and socket. This will cause
124 * remote_name to be freed.
125 */
126
127int
128channel_allocate(int type, int sock, char *remote_name)
129{
130 int i, found;
131 Channel *c;
132
133 /* Update the maximum file descriptor value. */
134 if (sock > channel_max_fd_value)
135 channel_max_fd_value = sock;
136 /* XXX set close-on-exec -markus */
137
138 /* Do initial allocation if this is the first call. */
139 if (channels_alloc == 0) {
140 channels_alloc = 10;
141 channels = xmalloc(channels_alloc * sizeof(Channel));
142 for (i = 0; i < channels_alloc; i++)
143 channels[i].type = SSH_CHANNEL_FREE;
144 /*
145 * Kludge: arrange a call to channel_stop_listening if we
146 * terminate with fatal().
147 */
148 fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
149 }
150 /* Try to find a free slot where to put the new channel. */
151 for (found = -1, i = 0; i < channels_alloc; i++)
152 if (channels[i].type == SSH_CHANNEL_FREE) {
153 /* Found a free slot. */
154 found = i;
155 break;
156 }
157 if (found == -1) {
158 /* There are no free slots. Take last+1 slot and expand the array. */
159 found = channels_alloc;
160 channels_alloc += 10;
161 debug("channel: expanding %d", channels_alloc);
162 channels = xrealloc(channels, channels_alloc * sizeof(Channel));
163 for (i = found; i < channels_alloc; i++)
164 channels[i].type = SSH_CHANNEL_FREE;
165 }
166 /* Initialize and return new channel number. */
167 c = &channels[found];
168 buffer_init(&c->input);
169 buffer_init(&c->output);
170 chan_init_iostates(c);
171 c->self = found;
172 c->type = type;
173 c->sock = sock;
174 c->remote_id = -1;
175 c->remote_name = remote_name;
176 debug("channel %d: new [%s]", found, remote_name);
177 return found;
178}
179
180/* Free the channel and close its socket. */
181
182void
183channel_free(int channel)
184{
185 if (channel < 0 || channel >= channels_alloc ||
186 channels[channel].type == SSH_CHANNEL_FREE)
187 packet_disconnect("channel free: bad local channel %d", channel);
188
189 if (compat13)
190 shutdown(channels[channel].sock, SHUT_RDWR);
191 close(channels[channel].sock);
192 buffer_free(&channels[channel].input);
193 buffer_free(&channels[channel].output);
194 channels[channel].type = SSH_CHANNEL_FREE;
195 if (channels[channel].remote_name) {
196 xfree(channels[channel].remote_name);
197 channels[channel].remote_name = NULL;
198 }
199}
200
201/*
202 * This is called just before select() to add any bits relevant to channels
203 * in the select bitmasks.
204 */
205
206void
207channel_prepare_select(fd_set * readset, fd_set * writeset)
208{
209 int i;
210 Channel *ch;
211 unsigned char *ucp;
212 unsigned int proto_len, data_len;
213
214 for (i = 0; i < channels_alloc; i++) {
215 ch = &channels[i];
216redo:
217 switch (ch->type) {
218 case SSH_CHANNEL_X11_LISTENER:
219 case SSH_CHANNEL_PORT_LISTENER:
220 case SSH_CHANNEL_AUTH_SOCKET:
221 FD_SET(ch->sock, readset);
222 break;
223
224 case SSH_CHANNEL_OPEN:
225 if (compat13) {
226 if (buffer_len(&ch->input) < packet_get_maxsize())
227 FD_SET(ch->sock, readset);
228 if (buffer_len(&ch->output) > 0)
229 FD_SET(ch->sock, writeset);
230 break;
231 }
232 /* test whether sockets are 'alive' for read/write */
233 if (ch->istate == CHAN_INPUT_OPEN)
234 if (buffer_len(&ch->input) < packet_get_maxsize())
235 FD_SET(ch->sock, readset);
236 if (ch->ostate == CHAN_OUTPUT_OPEN ||
237 ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
238 if (buffer_len(&ch->output) > 0) {
239 FD_SET(ch->sock, writeset);
240 } else if (ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
241 chan_obuf_empty(ch);
242 }
243 }
244 break;
245
246 case SSH_CHANNEL_INPUT_DRAINING:
247 if (!compat13)
248 fatal("cannot happen: IN_DRAIN");
249 if (buffer_len(&ch->input) == 0) {
250 packet_start(SSH_MSG_CHANNEL_CLOSE);
251 packet_put_int(ch->remote_id);
252 packet_send();
253 ch->type = SSH_CHANNEL_CLOSED;
254 debug("Closing channel %d after input drain.", ch->self);
255 break;
256 }
257 break;
258
259 case SSH_CHANNEL_OUTPUT_DRAINING:
260 if (!compat13)
261 fatal("cannot happen: OUT_DRAIN");
262 if (buffer_len(&ch->output) == 0) {
263 channel_free(i);
264 break;
265 }
266 FD_SET(ch->sock, writeset);
267 break;
268
269 case SSH_CHANNEL_X11_OPEN:
270 /*
271 * This is a special state for X11 authentication
272 * spoofing. An opened X11 connection (when
273 * authentication spoofing is being done) remains in
274 * this state until the first packet has been
275 * completely read. The authentication data in that
276 * packet is then substituted by the real data if it
277 * matches the fake data, and the channel is put into
278 * normal mode.
279 */
280 /* Check if the fixed size part of the packet is in buffer. */
281 if (buffer_len(&ch->output) < 12)
282 break;
283
284 /* Parse the lengths of variable-length fields. */
285 ucp = (unsigned char *) buffer_ptr(&ch->output);
286 if (ucp[0] == 0x42) { /* Byte order MSB first. */
287 proto_len = 256 * ucp[6] + ucp[7];
288 data_len = 256 * ucp[8] + ucp[9];
289 } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
290 proto_len = ucp[6] + 256 * ucp[7];
291 data_len = ucp[8] + 256 * ucp[9];
292 } else {
293 debug("Initial X11 packet contains bad byte order byte: 0x%x",
294 ucp[0]);
295 ch->type = SSH_CHANNEL_OPEN;
296 goto reject;
297 }
298
299 /* Check if the whole packet is in buffer. */
300 if (buffer_len(&ch->output) <
301 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
302 break;
303
304 /* Check if authentication protocol matches. */
305 if (proto_len != strlen(x11_saved_proto) ||
306 memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
307 debug("X11 connection uses different authentication protocol.");
308 ch->type = SSH_CHANNEL_OPEN;
309 goto reject;
310 }
311 /* Check if authentication data matches our fake data. */
312 if (data_len != x11_fake_data_len ||
313 memcmp(ucp + 12 + ((proto_len + 3) & ~3),
314 x11_fake_data, x11_fake_data_len) != 0) {
315 debug("X11 auth data does not match fake data.");
316 ch->type = SSH_CHANNEL_OPEN;
317 goto reject;
318 }
319 /* Check fake data length */
320 if (x11_fake_data_len != x11_saved_data_len) {
321 error("X11 fake_data_len %d != saved_data_len %d",
322 x11_fake_data_len, x11_saved_data_len);
323 ch->type = SSH_CHANNEL_OPEN;
324 goto reject;
325 }
326 /*
327 * Received authentication protocol and data match
328 * our fake data. Substitute the fake data with real
329 * data.
330 */
331 memcpy(ucp + 12 + ((proto_len + 3) & ~3),
332 x11_saved_data, x11_saved_data_len);
333
334 /* Start normal processing for the channel. */
335 ch->type = SSH_CHANNEL_OPEN;
336 goto redo;
337
338 reject:
339 /*
340 * We have received an X11 connection that has bad
341 * authentication information.
342 */
343 log("X11 connection rejected because of wrong authentication.\r\n");
344 buffer_clear(&ch->input);
345 buffer_clear(&ch->output);
346 if (compat13) {
347 close(ch->sock);
348 ch->sock = -1;
349 ch->type = SSH_CHANNEL_CLOSED;
350 packet_start(SSH_MSG_CHANNEL_CLOSE);
351 packet_put_int(ch->remote_id);
352 packet_send();
353 } else {
354 debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
355 chan_read_failed(ch);
356 chan_write_failed(ch);
357 debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
358 }
359 break;
360
361 case SSH_CHANNEL_FREE:
362 default:
363 continue;
364 }
365 }
366}
367
368/*
369 * After select, perform any appropriate operations for channels which have
370 * events pending.
371 */
372
373void
374channel_after_select(fd_set * readset, fd_set * writeset)
375{
376 struct sockaddr addr;
377 int newsock, i, newch, len;
378 socklen_t addrlen;
379 Channel *ch;
380 char buf[16384], *remote_hostname;
381
382 /* Loop over all channels... */
383 for (i = 0; i < channels_alloc; i++) {
384 ch = &channels[i];
385 switch (ch->type) {
386 case SSH_CHANNEL_X11_LISTENER:
387 /* This is our fake X11 server socket. */
388 if (FD_ISSET(ch->sock, readset)) {
389 debug("X11 connection requested.");
390 addrlen = sizeof(addr);
391 newsock = accept(ch->sock, &addr, &addrlen);
392 if (newsock < 0) {
393 error("accept: %.100s", strerror(errno));
394 break;
395 }
396 remote_hostname = get_remote_hostname(newsock);
397 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
398 remote_hostname, get_peer_port(newsock));
399 xfree(remote_hostname);
400 newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
401 xstrdup(buf));
402 packet_start(SSH_SMSG_X11_OPEN);
403 packet_put_int(newch);
404 if (have_hostname_in_open)
405 packet_put_string(buf, strlen(buf));
406 packet_send();
407 }
408 break;
409
410 case SSH_CHANNEL_PORT_LISTENER:
411 /*
412 * This socket is listening for connections to a
413 * forwarded TCP/IP port.
414 */
415 if (FD_ISSET(ch->sock, readset)) {
416 debug("Connection to port %d forwarding to %.100s port %d requested.",
417 ch->listening_port, ch->path, ch->host_port);
418 addrlen = sizeof(addr);
419 newsock = accept(ch->sock, &addr, &addrlen);
420 if (newsock < 0) {
421 error("accept: %.100s", strerror(errno));
422 break;
423 }
424 remote_hostname = get_remote_hostname(newsock);
425 snprintf(buf, sizeof buf, "listen port %d for %.100s port %d, connect from %.200s port %d",
426 ch->listening_port, ch->path, ch->host_port,
427 remote_hostname, get_peer_port(newsock));
428 xfree(remote_hostname);
429 newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
430 xstrdup(buf));
431 packet_start(SSH_MSG_PORT_OPEN);
432 packet_put_int(newch);
433 packet_put_string(ch->path, strlen(ch->path));
434 packet_put_int(ch->host_port);
435 if (have_hostname_in_open)
436 packet_put_string(buf, strlen(buf));
437 packet_send();
438 }
439 break;
440
441 case SSH_CHANNEL_AUTH_SOCKET:
442 /*
443 * This is the authentication agent socket listening
444 * for connections from clients.
445 */
446 if (FD_ISSET(ch->sock, readset)) {
447 addrlen = sizeof(addr);
448 newsock = accept(ch->sock, &addr, &addrlen);
449 if (newsock < 0) {
450 error("accept from auth socket: %.100s", strerror(errno));
451 break;
452 }
453 newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
454 xstrdup("accepted auth socket"));
455 packet_start(SSH_SMSG_AGENT_OPEN);
456 packet_put_int(newch);
457 packet_send();
458 }
459 break;
460
461 case SSH_CHANNEL_OPEN:
462 /*
463 * This is an open two-way communication channel. It
464 * is not of interest to us at this point what kind
465 * of data is being transmitted.
466 */
467
468 /*
469 * Read available incoming data and append it to
470 * buffer; shutdown socket, if read or write failes
471 */
472 if (FD_ISSET(ch->sock, readset)) {
473 len = read(ch->sock, buf, sizeof(buf));
474 if (len <= 0) {
475 if (compat13) {
476 buffer_consume(&ch->output, buffer_len(&ch->output));
477 ch->type = SSH_CHANNEL_INPUT_DRAINING;
478 debug("Channel %d status set to input draining.", i);
479 } else {
480 chan_read_failed(ch);
481 }
482 break;
483 }
484 buffer_append(&ch->input, buf, len);
485 }
486 /* Send buffered output data to the socket. */
487 if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
488 len = write(ch->sock, buffer_ptr(&ch->output),
489 buffer_len(&ch->output));
490 if (len <= 0) {
491 if (compat13) {
492 buffer_consume(&ch->output, buffer_len(&ch->output));
493 debug("Channel %d status set to input draining.", i);
494 ch->type = SSH_CHANNEL_INPUT_DRAINING;
495 } else {
496 chan_write_failed(ch);
497 }
498 break;
499 }
500 buffer_consume(&ch->output, len);
501 }
502 break;
503
504 case SSH_CHANNEL_OUTPUT_DRAINING:
505 if (!compat13)
506 fatal("cannot happen: OUT_DRAIN");
507 /* Send buffered output data to the socket. */
508 if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
509 len = write(ch->sock, buffer_ptr(&ch->output),
510 buffer_len(&ch->output));
511 if (len <= 0)
512 buffer_consume(&ch->output, buffer_len(&ch->output));
513 else
514 buffer_consume(&ch->output, len);
515 }
516 break;
517
518 case SSH_CHANNEL_X11_OPEN:
519 case SSH_CHANNEL_FREE:
520 default:
521 continue;
522 }
523 }
524}
525
526/* If there is data to send to the connection, send some of it now. */
527
528void
529channel_output_poll()
530{
531 int len, i;
532 Channel *ch;
533
534 for (i = 0; i < channels_alloc; i++) {
535 ch = &channels[i];
536
537 /* We are only interested in channels that can have buffered incoming data. */
538 if (compat13) {
539 if (ch->type != SSH_CHANNEL_OPEN &&
540 ch->type != SSH_CHANNEL_INPUT_DRAINING)
541 continue;
542 } else {
543 if (ch->type != SSH_CHANNEL_OPEN)
544 continue;
545 if (ch->istate != CHAN_INPUT_OPEN &&
546 ch->istate != CHAN_INPUT_WAIT_DRAIN)
547 continue;
548 }
549
550 /* Get the amount of buffered data for this channel. */
551 len = buffer_len(&ch->input);
552 if (len > 0) {
553 /* Send some data for the other side over the secure connection. */
554 if (packet_is_interactive()) {
555 if (len > 1024)
556 len = 512;
557 } else {
558 /* Keep the packets at reasonable size. */
559 if (len > packet_get_maxsize()/2)
560 len = packet_get_maxsize()/2;
561 }
562 packet_start(SSH_MSG_CHANNEL_DATA);
563 packet_put_int(ch->remote_id);
564 packet_put_string(buffer_ptr(&ch->input), len);
565 packet_send();
566 buffer_consume(&ch->input, len);
567 } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) {
568 if (compat13)
569 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
570 /*
571 * input-buffer is empty and read-socket shutdown:
572 * tell peer, that we will not send more data: send IEOF
573 */
574 chan_ibuf_empty(ch);
575 }
576 }
577}
578
579/*
580 * This is called when a packet of type CHANNEL_DATA has just been received.
581 * The message type has already been consumed, but channel number and data is
582 * still there.
583 */
584
585void
586channel_input_data(int payload_len)
587{
588 int id;
589 char *data;
590 unsigned int data_len;
591 Channel *ch;
592
593 /* Get the channel number and verify it. */
594 id = packet_get_int();
595 if (id < 0 || id >= channels_alloc)
596 packet_disconnect("Received data for nonexistent channel %d.", id);
597 ch = &channels[id];
598
599 if (ch->type == SSH_CHANNEL_FREE)
600 packet_disconnect("Received data for free channel %d.", ch->self);
601
602 /* Ignore any data for non-open channels (might happen on close) */
603 if (ch->type != SSH_CHANNEL_OPEN &&
604 ch->type != SSH_CHANNEL_X11_OPEN)
605 return;
606
607 /* same for protocol 1.5 if output end is no longer open */
608 if (!compat13 && ch->ostate != CHAN_OUTPUT_OPEN)
609 return;
610
611 /* Get the data. */
612 data = packet_get_string(&data_len);
613 packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA);
614 buffer_append(&ch->output, data, data_len);
615 xfree(data);
616}
617
618/*
619 * Returns true if no channel has too much buffered data, and false if one or
620 * more channel is overfull.
621 */
622
623int
624channel_not_very_much_buffered_data()
625{
626 unsigned int i;
627 Channel *ch;
628
629 for (i = 0; i < channels_alloc; i++) {
630 ch = &channels[i];
631 if (ch->type == SSH_CHANNEL_OPEN) {
632 if (buffer_len(&ch->input) > packet_get_maxsize())
633 return 0;
634 if (buffer_len(&ch->output) > packet_get_maxsize())
635 return 0;
636 }
637 }
638 return 1;
639}
640
641/* This is called after receiving CHANNEL_CLOSE/IEOF. */
642
643void
644channel_input_close()
645{
646 int channel;
647
648 /* Get the channel number and verify it. */
649 channel = packet_get_int();
650 if (channel < 0 || channel >= channels_alloc ||
651 channels[channel].type == SSH_CHANNEL_FREE)
652 packet_disconnect("Received data for nonexistent channel %d.", channel);
653
654 if (!compat13) {
655 /* proto version 1.5 overloads CLOSE with IEOF */
656 chan_rcvd_ieof(&channels[channel]);
657 return;
658 }
659
660 /*
661 * Send a confirmation that we have closed the channel and no more
662 * data is coming for it.
663 */
664 packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
665 packet_put_int(channels[channel].remote_id);
666 packet_send();
667
668 /*
669 * If the channel is in closed state, we have sent a close request,
670 * and the other side will eventually respond with a confirmation.
671 * Thus, we cannot free the channel here, because then there would be
672 * no-one to receive the confirmation. The channel gets freed when
673 * the confirmation arrives.
674 */
675 if (channels[channel].type != SSH_CHANNEL_CLOSED) {
676 /*
677 * Not a closed channel - mark it as draining, which will
678 * cause it to be freed later.
679 */
680 buffer_consume(&channels[channel].input,
681 buffer_len(&channels[channel].input));
682 channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING;
683 }
684}
685
686/* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */
687
688void
689channel_input_close_confirmation()
690{
691 int channel;
692
693 /* Get the channel number and verify it. */
694 channel = packet_get_int();
695 if (channel < 0 || channel >= channels_alloc)
696 packet_disconnect("Received close confirmation for out-of-range channel %d.",
697 channel);
698
699 if (!compat13) {
700 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
701 chan_rcvd_oclose(&channels[channel]);
702 return;
703 }
704 if (channels[channel].type != SSH_CHANNEL_CLOSED)
705 packet_disconnect("Received close confirmation for non-closed channel %d (type %d).",
706 channel, channels[channel].type);
707
708 /* Free the channel. */
709 channel_free(channel);
710}
711
712/* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
713
714void
715channel_input_open_confirmation()
716{
717 int channel, remote_channel;
718
719 /* Get the channel number and verify it. */
720 channel = packet_get_int();
721 if (channel < 0 || channel >= channels_alloc ||
722 channels[channel].type != SSH_CHANNEL_OPENING)
723 packet_disconnect("Received open confirmation for non-opening channel %d.",
724 channel);
725
726 /* Get remote side's id for this channel. */
727 remote_channel = packet_get_int();
728
729 /* Record the remote channel number and mark that the channel is now open. */
730 channels[channel].remote_id = remote_channel;
731 channels[channel].type = SSH_CHANNEL_OPEN;
732}
733
734/* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
735
736void
737channel_input_open_failure()
738{
739 int channel;
740
741 /* Get the channel number and verify it. */
742 channel = packet_get_int();
743 if (channel < 0 || channel >= channels_alloc ||
744 channels[channel].type != SSH_CHANNEL_OPENING)
745 packet_disconnect("Received open failure for non-opening channel %d.",
746 channel);
747
748 /* Free the channel. This will also close the socket. */
749 channel_free(channel);
750}
751
752/*
753 * Stops listening for channels, and removes any unix domain sockets that we
754 * might have.
755 */
756
757void
758channel_stop_listening()
759{
760 int i;
761 for (i = 0; i < channels_alloc; i++) {
762 switch (channels[i].type) {
763 case SSH_CHANNEL_AUTH_SOCKET:
764 close(channels[i].sock);
765 remove(channels[i].path);
766 channel_free(i);
767 break;
768 case SSH_CHANNEL_PORT_LISTENER:
769 case SSH_CHANNEL_X11_LISTENER:
770 close(channels[i].sock);
771 channel_free(i);
772 break;
773 default:
774 break;
775 }
776 }
777}
778
779/*
780 * Closes the sockets of all channels. This is used to close extra file
781 * descriptors after a fork.
782 */
783
784void
785channel_close_all()
786{
787 int i;
788 for (i = 0; i < channels_alloc; i++) {
789 if (channels[i].type != SSH_CHANNEL_FREE)
790 close(channels[i].sock);
791 }
792}
793
794/* Returns the maximum file descriptor number used by the channels. */
795
796int
797channel_max_fd()
798{
799 return channel_max_fd_value;
800}
801
802/* Returns true if any channel is still open. */
803
804int
805channel_still_open()
806{
807 unsigned int i;
808 for (i = 0; i < channels_alloc; i++)
809 switch (channels[i].type) {
810 case SSH_CHANNEL_FREE:
811 case SSH_CHANNEL_X11_LISTENER:
812 case SSH_CHANNEL_PORT_LISTENER:
813 case SSH_CHANNEL_CLOSED:
814 case SSH_CHANNEL_AUTH_SOCKET:
815 continue;
816 case SSH_CHANNEL_OPENING:
817 case SSH_CHANNEL_OPEN:
818 case SSH_CHANNEL_X11_OPEN:
819 return 1;
820 case SSH_CHANNEL_INPUT_DRAINING:
821 case SSH_CHANNEL_OUTPUT_DRAINING:
822 if (!compat13)
823 fatal("cannot happen: OUT_DRAIN");
824 return 1;
825 default:
826 fatal("channel_still_open: bad channel type %d", channels[i].type);
827 /* NOTREACHED */
828 }
829 return 0;
830}
831
832/*
833 * Returns a message describing the currently open forwarded connections,
834 * suitable for sending to the client. The message contains crlf pairs for
835 * newlines.
836 */
837
838char *
839channel_open_message()
840{
841 Buffer buffer;
842 int i;
843 char buf[512], *cp;
844
845 buffer_init(&buffer);
846 snprintf(buf, sizeof buf, "The following connections are open:\r\n");
847 buffer_append(&buffer, buf, strlen(buf));
848 for (i = 0; i < channels_alloc; i++) {
849 Channel *c = &channels[i];
850 switch (c->type) {
851 case SSH_CHANNEL_FREE:
852 case SSH_CHANNEL_X11_LISTENER:
853 case SSH_CHANNEL_PORT_LISTENER:
854 case SSH_CHANNEL_CLOSED:
855 case SSH_CHANNEL_AUTH_SOCKET:
856 continue;
857 case SSH_CHANNEL_OPENING:
858 case SSH_CHANNEL_OPEN:
859 case SSH_CHANNEL_X11_OPEN:
860 case SSH_CHANNEL_INPUT_DRAINING:
861 case SSH_CHANNEL_OUTPUT_DRAINING:
862 snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d/%d o%d/%d)\r\n",
863 c->self, c->remote_name,
864 c->type, c->remote_id,
865 c->istate, buffer_len(&c->input),
866 c->ostate, buffer_len(&c->output));
867 buffer_append(&buffer, buf, strlen(buf));
868 continue;
869 default:
870 fatal("channel_still_open: bad channel type %d", c->type);
871 /* NOTREACHED */
872 }
873 }
874 buffer_append(&buffer, "\0", 1);
875 cp = xstrdup(buffer_ptr(&buffer));
876 buffer_free(&buffer);
877 return cp;
878}
879
880/*
881 * Initiate forwarding of connections to local port "port" through the secure
882 * channel to host:port from remote side.
883 */
884
885void
886channel_request_local_forwarding(u_short port, const char *host,
887 u_short host_port, int gateway_ports)
888{
889 int success, ch, sock, on = 1;
890 struct addrinfo hints, *ai, *aitop;
891 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
892 struct linger linger;
893
894 if (strlen(host) > sizeof(channels[0].path) - 1)
895 packet_disconnect("Forward host name too long.");
896
897 /*
898 * getaddrinfo returns a loopback address if the hostname is
899 * set to NULL and hints.ai_flags is not AI_PASSIVE
900 */
901 memset(&hints, 0, sizeof(hints));
902 hints.ai_family = IPv4or6;
903 hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
904 hints.ai_socktype = SOCK_STREAM;
905 snprintf(strport, sizeof strport, "%d", port);
906 if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
907 packet_disconnect("getaddrinfo: fatal error");
908
909 success = 0;
910 for (ai = aitop; ai; ai = ai->ai_next) {
911 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
912 continue;
913 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
914 strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
915 error("channel_request_local_forwarding: getnameinfo failed");
916 continue;
917 }
918 /* Create a port to listen for the host. */
919 sock = socket(ai->ai_family, SOCK_STREAM, 0);
920 if (sock < 0) {
921 /* this is no error since kernel may not support ipv6 */
922 verbose("socket: %.100s", strerror(errno));
923 continue;
924 }
925 /*
926 * Set socket options. We would like the socket to disappear
927 * as soon as it has been closed for whatever reason.
928 */
929 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
930 linger.l_onoff = 1;
931 linger.l_linger = 5;
932 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
933 debug("Local forwarding listening on %s port %s.", ntop, strport);
934
935 /* Bind the socket to the address. */
936 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
937 /* address can be in use ipv6 address is already bound */
938 verbose("bind: %.100s", strerror(errno));
939 close(sock);
940 continue;
941 }
942 /* Start listening for connections on the socket. */
943 if (listen(sock, 5) < 0) {
944 error("listen: %.100s", strerror(errno));
945 close(sock);
946 continue;
947 }
948 /* Allocate a channel number for the socket. */
949 ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
950 xstrdup("port listener"));
951 strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
952 channels[ch].host_port = host_port;
953 channels[ch].listening_port = port;
954 success = 1;
955 }
956 if (success == 0)
957 packet_disconnect("cannot listen port: %d", port);
958 freeaddrinfo(aitop);
959}
960
961/*
962 * Initiate forwarding of connections to port "port" on remote host through
963 * the secure channel to host:port from local side.
964 */
965
966void
967channel_request_remote_forwarding(u_short port, const char *host,
968 u_short remote_port)
969{
970 int payload_len;
971 /* Record locally that connection to this host/port is permitted. */
972 if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
973 fatal("channel_request_remote_forwarding: too many forwards");
974
975 permitted_opens[num_permitted_opens].host = xstrdup(host);
976 permitted_opens[num_permitted_opens].port = remote_port;
977 num_permitted_opens++;
978
979 /* Send the forward request to the remote side. */
980 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
981 packet_put_int(port);
982 packet_put_string(host, strlen(host));
983 packet_put_int(remote_port);
984 packet_send();
985 packet_write_wait();
986
987 /*
988 * Wait for response from the remote side. It will send a disconnect
989 * message on failure, and we will never see it here.
990 */
991 packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
992}
993
994/*
995 * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
996 * listening for the port, and sends back a success reply (or disconnect
997 * message if there was an error). This never returns if there was an error.
998 */
999
1000void
1001channel_input_port_forward_request(int is_root)
1002{
1003 u_short port, host_port;
1004 char *hostname;
1005
1006 /* Get arguments from the packet. */
1007 port = packet_get_int();
1008 hostname = packet_get_string(NULL);
1009 host_port = packet_get_int();
1010
1011 /*
1012 * Check that an unprivileged user is not trying to forward a
1013 * privileged port.
1014 */
1015 if (port < IPPORT_RESERVED && !is_root)
1016 packet_disconnect("Requested forwarding of port %d but user is not root.",
1017 port);
1018 /*
1019 * Initiate forwarding,
1020 * bind port to localhost only (gateway ports == 0).
1021 */
1022 channel_request_local_forwarding(port, hostname, host_port, 0);
1023
1024 /* Free the argument string. */
1025 xfree(hostname);
1026}
1027
1028/*
1029 * This is called after receiving PORT_OPEN message. This attempts to
1030 * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
1031 * or CHANNEL_OPEN_FAILURE.
1032 */
1033
1034void
1035channel_input_port_open(int payload_len)
1036{
1037 int remote_channel, sock = 0, newch, i;
1038 u_short host_port;
1039 char *host, *originator_string;
|
1040 int host_len, originator_len;
|
| 1040 unsigned int host_len, originator_len; |
1041 struct addrinfo hints, *ai, *aitop;
1042 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1043 int gaierr;
1044
1045 /* Get remote channel number. */
1046 remote_channel = packet_get_int();
1047
1048 /* Get host name to connect to. */
1049 host = packet_get_string(&host_len);
1050
1051 /* Get port to connect to. */
1052 host_port = packet_get_int();
1053
1054 /* Get remote originator name. */
1055 if (have_hostname_in_open) {
1056 originator_string = packet_get_string(&originator_len);
1057 originator_len += 4; /* size of packet_int */
1058 } else {
1059 originator_string = xstrdup("unknown (remote did not supply name)");
1060 originator_len = 0; /* no originator supplied */
1061 }
1062
1063 packet_integrity_check(payload_len,
1064 4 + 4 + host_len + 4 + originator_len,
1065 SSH_MSG_PORT_OPEN);
1066
1067 /* Check if opening that port is permitted. */
1068 if (!all_opens_permitted) {
1069 /* Go trough all permitted ports. */
1070 for (i = 0; i < num_permitted_opens; i++)
1071 if (permitted_opens[i].port == host_port &&
1072 strcmp(permitted_opens[i].host, host) == 0)
1073 break;
1074
1075 /* Check if we found the requested port among those permitted. */
1076 if (i >= num_permitted_opens) {
1077 /* The port is not permitted. */
1078 log("Received request to connect to %.100s:%d, but the request was denied.",
1079 host, host_port);
1080 goto fail;
1081 }
1082 }
1083
1084 memset(&hints, 0, sizeof(hints));
1085 hints.ai_family = IPv4or6;
1086 hints.ai_socktype = SOCK_STREAM;
1087 snprintf(strport, sizeof strport, "%d", host_port);
1088 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
1089 error("%.100s: unknown host (%s)", host, gai_strerror(gaierr));
1090 goto fail;
1091 }
1092
1093 for (ai = aitop; ai; ai = ai->ai_next) {
1094 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1095 continue;
1096 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1097 strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1098 error("channel_input_port_open: getnameinfo failed");
1099 continue;
1100 }
1101 /* Create the socket. */
1102 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1103 if (sock < 0) {
1104 error("socket: %.100s", strerror(errno));
1105 continue;
1106 }
1107 /* Connect to the host/port. */
1108 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1109 error("connect %.100s port %s: %.100s", ntop, strport,
1110 strerror(errno));
1111 close(sock);
1112 continue; /* fail -- try next */
1113 }
1114 break; /* success */
1115
1116 }
1117 freeaddrinfo(aitop);
1118
1119 if (!ai) {
1120 error("connect %.100s port %d: failed.", host, host_port);
1121 goto fail;
1122 }
1123
1124 /* Successful connection. */
1125
1126 /* Allocate a channel for this connection. */
1127 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1128 channels[newch].remote_id = remote_channel;
1129
1130 /* Send a confirmation to the remote host. */
1131 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1132 packet_put_int(remote_channel);
1133 packet_put_int(newch);
1134 packet_send();
1135
1136 /* Free the argument string. */
1137 xfree(host);
1138
1139 return;
1140
1141fail:
1142 /* Free the argument string. */
1143 xfree(host);
1144
1145 /* Send refusal to the remote host. */
1146 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1147 packet_put_int(remote_channel);
1148 packet_send();
1149}
1150
1151/*
1152 * Creates an internet domain socket for listening for X11 connections.
1153 * Returns a suitable value for the DISPLAY variable, or NULL if an error
1154 * occurs.
1155 */
1156
1157#define NUM_SOCKS 10
1158
1159char *
1160x11_create_display_inet(int screen_number, int x11_display_offset)
1161{
1162 int display_number, sock;
1163 u_short port;
1164 struct addrinfo hints, *ai, *aitop;
1165 char strport[NI_MAXSERV];
1166 int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
1167 char display[512];
1168 char hostname[MAXHOSTNAMELEN];
1169
1170 for (display_number = x11_display_offset;
1171 display_number < MAX_DISPLAYS;
1172 display_number++) {
1173 port = 6000 + display_number;
1174 memset(&hints, 0, sizeof(hints));
1175 hints.ai_family = IPv4or6;
1176 hints.ai_flags = AI_PASSIVE; /* XXX loopback only ? */
1177 hints.ai_socktype = SOCK_STREAM;
1178 snprintf(strport, sizeof strport, "%d", port);
1179 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
1180 error("getaddrinfo: %.100s", gai_strerror(gaierr));
1181 return NULL;
1182 }
1183 for (ai = aitop; ai; ai = ai->ai_next) {
1184 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1185 continue;
1186 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1187 if (sock < 0) {
1188 error("socket: %.100s", strerror(errno));
1189 return NULL;
1190 }
1191 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1192 debug("bind port %d: %.100s", port, strerror(errno));
1193 shutdown(sock, SHUT_RDWR);
1194 close(sock);
1195 for (n = 0; n < num_socks; n++) {
1196 shutdown(socks[n], SHUT_RDWR);
1197 close(socks[n]);
1198 }
1199 num_socks = 0;
1200 break;
1201 }
1202 socks[num_socks++] = sock;
1203 if (num_socks == NUM_SOCKS)
1204 break;
1205 }
1206 if (num_socks > 0)
1207 break;
1208 }
1209 if (display_number >= MAX_DISPLAYS) {
1210 error("Failed to allocate internet-domain X11 display socket.");
1211 return NULL;
1212 }
1213 /* Start listening for connections on the socket. */
1214 for (n = 0; n < num_socks; n++) {
1215 sock = socks[n];
1216 if (listen(sock, 5) < 0) {
1217 error("listen: %.100s", strerror(errno));
1218 shutdown(sock, SHUT_RDWR);
1219 close(sock);
1220 return NULL;
1221 }
1222 }
1223
1224 /* Set up a suitable value for the DISPLAY variable. */
1225 if (gethostname(hostname, sizeof(hostname)) < 0)
1226 fatal("gethostname: %.100s", strerror(errno));
1227 snprintf(display, sizeof display, "%.400s:%d.%d", hostname,
1228 display_number, screen_number);
1229
1230 /* Allocate a channel for each socket. */
1231 for (n = 0; n < num_socks; n++) {
1232 sock = socks[n];
1233 (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
1234 xstrdup("X11 inet listener"));
1235 }
1236
1237 /* Return a suitable value for the DISPLAY environment variable. */
1238 return xstrdup(display);
1239}
1240
1241#ifndef X_UNIX_PATH
1242#define X_UNIX_PATH "/tmp/.X11-unix/X"
1243#endif
1244
1245static
1246int
1247connect_local_xsocket(unsigned int dnr)
1248{
1249 static const char *const x_sockets[] = {
1250 X_UNIX_PATH "%u",
1251 "/var/X/.X11-unix/X" "%u",
1252 "/usr/spool/sockets/X11/" "%u",
1253 NULL
1254 };
1255 int sock;
1256 struct sockaddr_un addr;
1257 const char *const * path;
1258
1259 for (path = x_sockets; *path; ++path) {
1260 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1261 if (sock < 0)
1262 error("socket: %.100s", strerror(errno));
1263 memset(&addr, 0, sizeof(addr));
1264 addr.sun_family = AF_UNIX;
1265 snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
1266 if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
1267 return sock;
1268 close(sock);
1269 }
1270 error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
1271 return -1;
1272}
1273
1274
1275/*
1276 * This is called when SSH_SMSG_X11_OPEN is received. The packet contains
1277 * the remote channel number. We should do whatever we want, and respond
1278 * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
1279 */
1280
1281void
1282x11_input_open(int payload_len)
1283{
1284 int remote_channel, display_number, sock = 0, newch;
1285 const char *display;
1286 char buf[1024], *cp, *remote_host;
|
1287 int remote_len;
|
| 1287 unsigned int remote_len; |
1288 struct addrinfo hints, *ai, *aitop;
1289 char strport[NI_MAXSERV];
1290 int gaierr;
1291
1292 /* Get remote channel number. */
1293 remote_channel = packet_get_int();
1294
1295 /* Get remote originator name. */
1296 if (have_hostname_in_open) {
1297 remote_host = packet_get_string(&remote_len);
1298 remote_len += 4;
1299 } else {
1300 remote_host = xstrdup("unknown (remote did not supply name)");
1301 remote_len = 0;
1302 }
1303
1304 debug("Received X11 open request.");
1305 packet_integrity_check(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN);
1306
1307 /* Try to open a socket for the local X server. */
1308 display = getenv("DISPLAY");
1309 if (!display) {
1310 error("DISPLAY not set.");
1311 goto fail;
1312 }
1313 /*
1314 * Now we decode the value of the DISPLAY variable and make a
1315 * connection to the real X server.
1316 */
1317
1318 /*
1319 * Check if it is a unix domain socket. Unix domain displays are in
1320 * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
1321 */
1322 if (strncmp(display, "unix:", 5) == 0 ||
1323 display[0] == ':') {
1324 /* Connect to the unix domain socket. */
1325 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
1326 error("Could not parse display number from DISPLAY: %.100s",
1327 display);
1328 goto fail;
1329 }
1330 /* Create a socket. */
1331 sock = connect_local_xsocket(display_number);
1332 if (sock < 0)
1333 goto fail;
1334
1335 /* OK, we now have a connection to the display. */
1336 goto success;
1337 }
1338 /*
1339 * Connect to an inet socket. The DISPLAY value is supposedly
1340 * hostname:d[.s], where hostname may also be numeric IP address.
1341 */
1342 strncpy(buf, display, sizeof(buf));
1343 buf[sizeof(buf) - 1] = 0;
1344 cp = strchr(buf, ':');
1345 if (!cp) {
1346 error("Could not find ':' in DISPLAY: %.100s", display);
1347 goto fail;
1348 }
1349 *cp = 0;
1350 /* buf now contains the host name. But first we parse the display number. */
1351 if (sscanf(cp + 1, "%d", &display_number) != 1) {
1352 error("Could not parse display number from DISPLAY: %.100s",
1353 display);
1354 goto fail;
1355 }
1356
1357 /* Look up the host address */
1358 memset(&hints, 0, sizeof(hints));
1359 hints.ai_family = IPv4or6;
1360 hints.ai_socktype = SOCK_STREAM;
1361 snprintf(strport, sizeof strport, "%d", 6000 + display_number);
1362 if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
1363 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
1364 goto fail;
1365 }
1366 for (ai = aitop; ai; ai = ai->ai_next) {
1367 /* Create a socket. */
1368 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1369 if (sock < 0) {
1370 debug("socket: %.100s", strerror(errno));
1371 continue;
1372 }
1373 /* Connect it to the display. */
1374 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1375 debug("connect %.100s port %d: %.100s", buf, 6000 + display_number,
1376 strerror(errno));
1377 close(sock);
1378 continue;
1379 }
1380 /* Success */
1381 break;
1382
1383 } /* (ai = aitop, ai; ai = ai->ai_next) */
1384 freeaddrinfo(aitop);
1385 if (!ai) {
1386 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
1387 strerror(errno));
1388 goto fail;
1389 }
1390success:
1391 /* We have successfully obtained a connection to the real X display. */
1392
1393 /* Allocate a channel for this connection. */
1394 if (x11_saved_proto == NULL)
1395 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1396 else
1397 newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1398 channels[newch].remote_id = remote_channel;
1399
1400 /* Send a confirmation to the remote host. */
1401 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1402 packet_put_int(remote_channel);
1403 packet_put_int(newch);
1404 packet_send();
1405
1406 return;
1407
1408fail:
1409 /* Send refusal to the remote host. */
1410 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1411 packet_put_int(remote_channel);
1412 packet_send();
1413}
1414
1415/*
1416 * Requests forwarding of X11 connections, generates fake authentication
1417 * data, and enables authentication spoofing.
1418 */
1419
1420void
1421x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1422{
1423 unsigned int data_len = (unsigned int) strlen(data) / 2;
1424 unsigned int i, value;
1425 char *new_data;
1426 int screen_number;
1427 const char *cp;
1428 u_int32_t rand = 0;
1429
1430 cp = getenv("DISPLAY");
1431 if (cp)
1432 cp = strchr(cp, ':');
1433 if (cp)
1434 cp = strchr(cp, '.');
1435 if (cp)
1436 screen_number = atoi(cp + 1);
1437 else
1438 screen_number = 0;
1439
1440 /* Save protocol name. */
1441 x11_saved_proto = xstrdup(proto);
1442
1443 /*
1444 * Extract real authentication data and generate fake data of the
1445 * same length.
1446 */
1447 x11_saved_data = xmalloc(data_len);
1448 x11_fake_data = xmalloc(data_len);
1449 for (i = 0; i < data_len; i++) {
1450 if (sscanf(data + 2 * i, "%2x", &value) != 1)
1451 fatal("x11_request_forwarding: bad authentication data: %.100s", data);
1452 if (i % 4 == 0)
1453 rand = arc4random();
1454 x11_saved_data[i] = value;
1455 x11_fake_data[i] = rand & 0xff;
1456 rand >>= 8;
1457 }
1458 x11_saved_data_len = data_len;
1459 x11_fake_data_len = data_len;
1460
1461 /* Convert the fake data into hex. */
1462 new_data = xmalloc(2 * data_len + 1);
1463 for (i = 0; i < data_len; i++)
1464 sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]);
1465
1466 /* Send the request packet. */
1467 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
1468 packet_put_string(proto, strlen(proto));
1469 packet_put_string(new_data, strlen(new_data));
1470 packet_put_int(screen_number);
1471 packet_send();
1472 packet_write_wait();
1473 xfree(new_data);
1474}
1475
1476/* Sends a message to the server to request authentication fd forwarding. */
1477
1478void
1479auth_request_forwarding()
1480{
1481 packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
1482 packet_send();
1483 packet_write_wait();
1484}
1485
1486/*
1487 * Returns the name of the forwarded authentication socket. Returns NULL if
1488 * there is no forwarded authentication socket. The returned value points to
1489 * a static buffer.
1490 */
1491
1492char *
1493auth_get_socket_name()
1494{
1495 return channel_forwarded_auth_socket_name;
1496}
1497
1498/* removes the agent forwarding socket */
1499
1500void
1501cleanup_socket(void)
1502{
1503 remove(channel_forwarded_auth_socket_name);
1504 rmdir(channel_forwarded_auth_socket_dir);
1505}
1506
1507/*
1508 * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
1509 * This starts forwarding authentication requests.
1510 */
1511
1512void
1513auth_input_request_forwarding(struct passwd * pw)
1514{
1515 int sock, newch;
1516 struct sockaddr_un sunaddr;
1517
1518 if (auth_get_socket_name() != NULL)
1519 fatal("Protocol error: authentication forwarding requested twice.");
1520
1521 /* Temporarily drop privileged uid for mkdir/bind. */
1522 temporarily_use_uid(pw->pw_uid);
1523
1524 /* Allocate a buffer for the socket name, and format the name. */
1525 channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
1526 channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
1527 strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
1528
1529 /* Create private directory for socket */
1530 if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
1531 packet_disconnect("mkdtemp: %.100s", strerror(errno));
1532 snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
1533 channel_forwarded_auth_socket_dir, (int) getpid());
1534
1535 if (atexit(cleanup_socket) < 0) {
1536 int saved = errno;
1537 cleanup_socket();
1538 packet_disconnect("socket: %.100s", strerror(saved));
1539 }
1540 /* Create the socket. */
1541 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1542 if (sock < 0)
1543 packet_disconnect("socket: %.100s", strerror(errno));
1544
1545 /* Bind it to the name. */
1546 memset(&sunaddr, 0, sizeof(sunaddr));
1547 sunaddr.sun_family = AF_UNIX;
1548 strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
1549 sizeof(sunaddr.sun_path));
1550
1551 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
1552 packet_disconnect("bind: %.100s", strerror(errno));
1553
1554 /* Restore the privileged uid. */
1555 restore_uid();
1556
1557 /* Start listening on the socket. */
1558 if (listen(sock, 5) < 0)
1559 packet_disconnect("listen: %.100s", strerror(errno));
1560
1561 /* Allocate a channel for the authentication agent socket. */
1562 newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
1563 xstrdup("auth socket"));
1564 strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
1565 sizeof(channels[newch].path));
1566}
1567
1568/* This is called to process an SSH_SMSG_AGENT_OPEN message. */
1569
1570void
1571auth_input_open_request()
1572{
1573 int remch, sock, newch;
1574 char *dummyname;
1575
1576 /* Read the remote channel number from the message. */
1577 remch = packet_get_int();
1578
1579 /*
1580 * Get a connection to the local authentication agent (this may again
1581 * get forwarded).
1582 */
1583 sock = ssh_get_authentication_socket();
1584
1585 /*
1586 * If we could not connect the agent, send an error message back to
1587 * the server. This should never happen unless the agent dies,
1588 * because authentication forwarding is only enabled if we have an
1589 * agent.
1590 */
1591 if (sock < 0) {
1592 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1593 packet_put_int(remch);
1594 packet_send();
1595 return;
1596 }
1597 debug("Forwarding authentication connection.");
1598
1599 /*
1600 * Dummy host name. This will be freed when the channel is freed; it
1601 * will still be valid in the packet_put_string below since the
1602 * channel cannot yet be freed at that point.
1603 */
1604 dummyname = xstrdup("authentication agent connection");
1605
1606 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
1607 channels[newch].remote_id = remch;
1608
1609 /* Send a confirmation to the remote host. */
1610 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1611 packet_put_int(remch);
1612 packet_put_int(newch);
1613 packet_send();
1614}
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