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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" | |
19 | RCSID("$Id$"); | |
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 | */ | |
44 | static 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 | */ | |
51 | static 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 | */ | |
57 | static int channel_max_fd_value = 0; | |
58 | ||
59 | /* Name and directory of socket for authentication agent forwarding. */ | |
60 | static char *channel_forwarded_auth_socket_name = NULL; | |
61 | static char *channel_forwarded_auth_socket_dir = NULL; | |
62 | ||
63 | /* Saved X11 authentication protocol name. */ | |
64 | char *x11_saved_proto = NULL; | |
65 | ||
66 | /* Saved X11 authentication data. This is the real data. */ | |
67 | char *x11_saved_data = NULL; | |
68 | unsigned 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 | */ | |
74 | char *x11_fake_data = NULL; | |
75 | unsigned 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 | */ | |
83 | typedef 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. */ | |
89 | static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION]; | |
90 | /* Number of permitted host/port pairs in the array. */ | |
91 | static 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 | */ | |
97 | static int all_opens_permitted = 0; | |
98 | ||
99 | /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */ | |
100 | static int have_hostname_in_open = 0; | |
101 | ||
102 | /* Sets specific protocol options. */ | |
103 | ||
104 | void | |
105 | channel_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 | ||
116 | void | |
117 | channel_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 | ||
127 | int | |
128 | channel_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 | ||
182 | void | |
183 | channel_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 | ||
206 | void | |
207 | channel_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]; | |
216 | redo: | |
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.", i); | |
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 | ||
373 | void | |
374 | channel_after_select(fd_set * readset, fd_set * writeset) | |
375 | { | |
376 | struct sockaddr addr; | |
377 | int addrlen, newsock, i, newch, len; | |
378 | Channel *ch; | |
379 | char buf[16384], *remote_hostname; | |
380 | ||
381 | /* Loop over all channels... */ | |
382 | for (i = 0; i < channels_alloc; i++) { | |
383 | ch = &channels[i]; | |
384 | switch (ch->type) { | |
385 | case SSH_CHANNEL_X11_LISTENER: | |
386 | /* This is our fake X11 server socket. */ | |
387 | if (FD_ISSET(ch->sock, readset)) { | |
388 | debug("X11 connection requested."); | |
389 | addrlen = sizeof(addr); | |
390 | newsock = accept(ch->sock, &addr, &addrlen); | |
391 | if (newsock < 0) { | |
392 | error("accept: %.100s", strerror(errno)); | |
393 | break; | |
394 | } | |
395 | remote_hostname = get_remote_hostname(newsock); | |
396 | snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", | |
397 | remote_hostname, get_peer_port(newsock)); | |
398 | xfree(remote_hostname); | |
399 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
400 | xstrdup(buf)); | |
401 | packet_start(SSH_SMSG_X11_OPEN); | |
402 | packet_put_int(newch); | |
403 | if (have_hostname_in_open) | |
404 | packet_put_string(buf, strlen(buf)); | |
405 | packet_send(); | |
406 | } | |
407 | break; | |
408 | ||
409 | case SSH_CHANNEL_PORT_LISTENER: | |
410 | /* | |
411 | * This socket is listening for connections to a | |
412 | * forwarded TCP/IP port. | |
413 | */ | |
414 | if (FD_ISSET(ch->sock, readset)) { | |
415 | debug("Connection to port %d forwarding to %.100s:%d requested.", | |
416 | ch->listening_port, ch->path, ch->host_port); | |
417 | addrlen = sizeof(addr); | |
418 | newsock = accept(ch->sock, &addr, &addrlen); | |
419 | if (newsock < 0) { | |
420 | error("accept: %.100s", strerror(errno)); | |
421 | break; | |
422 | } | |
423 | remote_hostname = get_remote_hostname(newsock); | |
424 | snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d", | |
425 | ch->listening_port, ch->path, ch->host_port, | |
426 | remote_hostname, get_peer_port(newsock)); | |
427 | xfree(remote_hostname); | |
428 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
429 | xstrdup(buf)); | |
430 | packet_start(SSH_MSG_PORT_OPEN); | |
431 | packet_put_int(newch); | |
432 | packet_put_string(ch->path, strlen(ch->path)); | |
433 | packet_put_int(ch->host_port); | |
434 | if (have_hostname_in_open) | |
435 | packet_put_string(buf, strlen(buf)); | |
436 | packet_send(); | |
437 | } | |
438 | break; | |
439 | ||
440 | case SSH_CHANNEL_AUTH_SOCKET: | |
441 | /* | |
442 | * This is the authentication agent socket listening | |
443 | * for connections from clients. | |
444 | */ | |
445 | if (FD_ISSET(ch->sock, readset)) { | |
446 | int nchan; | |
447 | len = sizeof(addr); | |
448 | newsock = accept(ch->sock, &addr, &len); | |
449 | if (newsock < 0) { | |
450 | error("accept from auth socket: %.100s", strerror(errno)); | |
451 | break; | |
452 | } | |
453 | nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
454 | xstrdup("accepted auth socket")); | |
455 | packet_start(SSH_SMSG_AGENT_OPEN); | |
456 | packet_put_int(nchan); | |
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 | ||
528 | void | |
529 | channel_output_poll() | |
530 | { | |
531 | int len, i; | |
532 | Channel *ch; | |
533 | ||
534 | for (i = 0; i < channels_alloc; i++) { | |
535 | ch = &channels[i]; | |
536 | /* We are only interested in channels that can have buffered incoming data. */ | |
537 | if (ch->type != SSH_CHANNEL_OPEN && | |
538 | ch->type != SSH_CHANNEL_INPUT_DRAINING) | |
539 | continue; | |
540 | ||
541 | /* Get the amount of buffered data for this channel. */ | |
542 | len = buffer_len(&ch->input); | |
543 | if (len > 0) { | |
544 | /* Send some data for the other side over the secure connection. */ | |
545 | if (packet_is_interactive()) { | |
546 | if (len > 1024) | |
547 | len = 512; | |
548 | } else { | |
549 | /* Keep the packets at reasonable size. */ | |
550 | if (len > 16384) | |
551 | len = 16384; | |
552 | } | |
553 | packet_start(SSH_MSG_CHANNEL_DATA); | |
554 | packet_put_int(ch->remote_id); | |
555 | packet_put_string(buffer_ptr(&ch->input), len); | |
556 | packet_send(); | |
557 | buffer_consume(&ch->input, len); | |
558 | } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) { | |
559 | if (compat13) | |
560 | fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); | |
561 | /* | |
562 | * input-buffer is empty and read-socket shutdown: | |
563 | * tell peer, that we will not send more data: send IEOF | |
564 | */ | |
565 | chan_ibuf_empty(ch); | |
566 | } | |
567 | } | |
568 | } | |
569 | ||
570 | /* | |
571 | * This is called when a packet of type CHANNEL_DATA has just been received. | |
572 | * The message type has already been consumed, but channel number and data is | |
573 | * still there. | |
574 | */ | |
575 | ||
576 | void | |
577 | channel_input_data(int payload_len) | |
578 | { | |
579 | int channel; | |
580 | char *data; | |
581 | unsigned int data_len; | |
582 | ||
583 | /* Get the channel number and verify it. */ | |
584 | channel = packet_get_int(); | |
585 | if (channel < 0 || channel >= channels_alloc || | |
586 | channels[channel].type == SSH_CHANNEL_FREE) | |
587 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
588 | ||
589 | /* Ignore any data for non-open channels (might happen on close) */ | |
590 | if (channels[channel].type != SSH_CHANNEL_OPEN && | |
591 | channels[channel].type != SSH_CHANNEL_X11_OPEN) | |
592 | return; | |
593 | ||
594 | /* Get the data. */ | |
595 | data = packet_get_string(&data_len); | |
596 | packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA); | |
597 | buffer_append(&channels[channel].output, data, data_len); | |
598 | xfree(data); | |
599 | } | |
600 | ||
601 | /* | |
602 | * Returns true if no channel has too much buffered data, and false if one or | |
603 | * more channel is overfull. | |
604 | */ | |
605 | ||
606 | int | |
607 | channel_not_very_much_buffered_data() | |
608 | { | |
609 | unsigned int i; | |
610 | Channel *ch; | |
611 | ||
612 | for (i = 0; i < channels_alloc; i++) { | |
613 | ch = &channels[i]; | |
614 | switch (ch->type) { | |
615 | case SSH_CHANNEL_X11_LISTENER: | |
616 | case SSH_CHANNEL_PORT_LISTENER: | |
617 | case SSH_CHANNEL_AUTH_SOCKET: | |
618 | continue; | |
619 | case SSH_CHANNEL_OPEN: | |
620 | if (buffer_len(&ch->input) > packet_get_maxsize()) | |
621 | return 0; | |
622 | if (buffer_len(&ch->output) > packet_get_maxsize()) | |
623 | return 0; | |
624 | continue; | |
625 | case SSH_CHANNEL_INPUT_DRAINING: | |
626 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
627 | case SSH_CHANNEL_X11_OPEN: | |
628 | case SSH_CHANNEL_FREE: | |
629 | default: | |
630 | continue; | |
631 | } | |
632 | } | |
633 | return 1; | |
634 | } | |
635 | ||
636 | /* This is called after receiving CHANNEL_CLOSE/IEOF. */ | |
637 | ||
638 | void | |
639 | channel_input_close() | |
640 | { | |
641 | int channel; | |
642 | ||
643 | /* Get the channel number and verify it. */ | |
644 | channel = packet_get_int(); | |
645 | if (channel < 0 || channel >= channels_alloc || | |
646 | channels[channel].type == SSH_CHANNEL_FREE) | |
647 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
648 | ||
649 | if (!compat13) { | |
650 | /* proto version 1.5 overloads CLOSE with IEOF */ | |
651 | chan_rcvd_ieof(&channels[channel]); | |
652 | return; | |
653 | } | |
654 | ||
655 | /* | |
656 | * Send a confirmation that we have closed the channel and no more | |
657 | * data is coming for it. | |
658 | */ | |
659 | packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); | |
660 | packet_put_int(channels[channel].remote_id); | |
661 | packet_send(); | |
662 | ||
663 | /* | |
664 | * If the channel is in closed state, we have sent a close request, | |
665 | * and the other side will eventually respond with a confirmation. | |
666 | * Thus, we cannot free the channel here, because then there would be | |
667 | * no-one to receive the confirmation. The channel gets freed when | |
668 | * the confirmation arrives. | |
669 | */ | |
670 | if (channels[channel].type != SSH_CHANNEL_CLOSED) { | |
671 | /* | |
672 | * Not a closed channel - mark it as draining, which will | |
673 | * cause it to be freed later. | |
674 | */ | |
675 | buffer_consume(&channels[channel].input, | |
676 | buffer_len(&channels[channel].input)); | |
677 | channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; | |
678 | } | |
679 | } | |
680 | ||
681 | /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ | |
682 | ||
683 | void | |
684 | channel_input_close_confirmation() | |
685 | { | |
686 | int channel; | |
687 | ||
688 | /* Get the channel number and verify it. */ | |
689 | channel = packet_get_int(); | |
690 | if (channel < 0 || channel >= channels_alloc) | |
691 | packet_disconnect("Received close confirmation for out-of-range channel %d.", | |
692 | channel); | |
693 | ||
694 | if (!compat13) { | |
695 | /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ | |
696 | chan_rcvd_oclose(&channels[channel]); | |
697 | return; | |
698 | } | |
699 | if (channels[channel].type != SSH_CHANNEL_CLOSED) | |
700 | packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", | |
701 | channel, channels[channel].type); | |
702 | ||
703 | /* Free the channel. */ | |
704 | channel_free(channel); | |
705 | } | |
706 | ||
707 | /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ | |
708 | ||
709 | void | |
710 | channel_input_open_confirmation() | |
711 | { | |
712 | int channel, remote_channel; | |
713 | ||
714 | /* Get the channel number and verify it. */ | |
715 | channel = packet_get_int(); | |
716 | if (channel < 0 || channel >= channels_alloc || | |
717 | channels[channel].type != SSH_CHANNEL_OPENING) | |
718 | packet_disconnect("Received open confirmation for non-opening channel %d.", | |
719 | channel); | |
720 | ||
721 | /* Get remote side's id for this channel. */ | |
722 | remote_channel = packet_get_int(); | |
723 | ||
724 | /* Record the remote channel number and mark that the channel is now open. */ | |
725 | channels[channel].remote_id = remote_channel; | |
726 | channels[channel].type = SSH_CHANNEL_OPEN; | |
727 | } | |
728 | ||
729 | /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ | |
730 | ||
731 | void | |
732 | channel_input_open_failure() | |
733 | { | |
734 | int channel; | |
735 | ||
736 | /* Get the channel number and verify it. */ | |
737 | channel = packet_get_int(); | |
738 | if (channel < 0 || channel >= channels_alloc || | |
739 | channels[channel].type != SSH_CHANNEL_OPENING) | |
740 | packet_disconnect("Received open failure for non-opening channel %d.", | |
741 | channel); | |
742 | ||
743 | /* Free the channel. This will also close the socket. */ | |
744 | channel_free(channel); | |
745 | } | |
746 | ||
747 | /* | |
748 | * Stops listening for channels, and removes any unix domain sockets that we | |
749 | * might have. | |
750 | */ | |
751 | ||
752 | void | |
753 | channel_stop_listening() | |
754 | { | |
755 | int i; | |
756 | for (i = 0; i < channels_alloc; i++) { | |
757 | switch (channels[i].type) { | |
758 | case SSH_CHANNEL_AUTH_SOCKET: | |
759 | close(channels[i].sock); | |
760 | remove(channels[i].path); | |
761 | channel_free(i); | |
762 | break; | |
763 | case SSH_CHANNEL_PORT_LISTENER: | |
764 | case SSH_CHANNEL_X11_LISTENER: | |
765 | close(channels[i].sock); | |
766 | channel_free(i); | |
767 | break; | |
768 | default: | |
769 | break; | |
770 | } | |
771 | } | |
772 | } | |
773 | ||
774 | /* | |
775 | * Closes the sockets of all channels. This is used to close extra file | |
776 | * descriptors after a fork. | |
777 | */ | |
778 | ||
779 | void | |
780 | channel_close_all() | |
781 | { | |
782 | int i; | |
783 | for (i = 0; i < channels_alloc; i++) { | |
784 | if (channels[i].type != SSH_CHANNEL_FREE) | |
785 | close(channels[i].sock); | |
786 | } | |
787 | } | |
788 | ||
789 | /* Returns the maximum file descriptor number used by the channels. */ | |
790 | ||
791 | int | |
792 | channel_max_fd() | |
793 | { | |
794 | return channel_max_fd_value; | |
795 | } | |
796 | ||
797 | /* Returns true if any channel is still open. */ | |
798 | ||
799 | int | |
800 | channel_still_open() | |
801 | { | |
802 | unsigned int i; | |
803 | for (i = 0; i < channels_alloc; i++) | |
804 | switch (channels[i].type) { | |
805 | case SSH_CHANNEL_FREE: | |
806 | case SSH_CHANNEL_X11_LISTENER: | |
807 | case SSH_CHANNEL_PORT_LISTENER: | |
808 | case SSH_CHANNEL_CLOSED: | |
809 | case SSH_CHANNEL_AUTH_SOCKET: | |
810 | continue; | |
811 | case SSH_CHANNEL_OPENING: | |
812 | case SSH_CHANNEL_OPEN: | |
813 | case SSH_CHANNEL_X11_OPEN: | |
814 | return 1; | |
815 | case SSH_CHANNEL_INPUT_DRAINING: | |
816 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
817 | if (!compat13) | |
818 | fatal("cannot happen: OUT_DRAIN"); | |
819 | return 1; | |
820 | default: | |
821 | fatal("channel_still_open: bad channel type %d", channels[i].type); | |
822 | /* NOTREACHED */ | |
823 | } | |
824 | return 0; | |
825 | } | |
826 | ||
827 | /* | |
828 | * Returns a message describing the currently open forwarded connections, | |
829 | * suitable for sending to the client. The message contains crlf pairs for | |
830 | * newlines. | |
831 | */ | |
832 | ||
833 | char * | |
834 | channel_open_message() | |
835 | { | |
836 | Buffer buffer; | |
837 | int i; | |
838 | char buf[512], *cp; | |
839 | ||
840 | buffer_init(&buffer); | |
841 | snprintf(buf, sizeof buf, "The following connections are open:\r\n"); | |
842 | buffer_append(&buffer, buf, strlen(buf)); | |
843 | for (i = 0; i < channels_alloc; i++) { | |
844 | Channel *c = &channels[i]; | |
845 | switch (c->type) { | |
846 | case SSH_CHANNEL_FREE: | |
847 | case SSH_CHANNEL_X11_LISTENER: | |
848 | case SSH_CHANNEL_PORT_LISTENER: | |
849 | case SSH_CHANNEL_CLOSED: | |
850 | case SSH_CHANNEL_AUTH_SOCKET: | |
851 | continue; | |
852 | case SSH_CHANNEL_OPENING: | |
853 | case SSH_CHANNEL_OPEN: | |
854 | case SSH_CHANNEL_X11_OPEN: | |
855 | case SSH_CHANNEL_INPUT_DRAINING: | |
856 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
857 | snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n", | |
858 | c->self, c->remote_name, | |
859 | c->type, c->remote_id, c->istate, c->ostate); | |
860 | buffer_append(&buffer, buf, strlen(buf)); | |
861 | continue; | |
862 | default: | |
863 | fatal("channel_still_open: bad channel type %d", c->type); | |
864 | /* NOTREACHED */ | |
865 | } | |
866 | } | |
867 | buffer_append(&buffer, "\0", 1); | |
868 | cp = xstrdup(buffer_ptr(&buffer)); | |
869 | buffer_free(&buffer); | |
870 | return cp; | |
871 | } | |
872 | ||
873 | /* | |
874 | * Initiate forwarding of connections to local port "port" through the secure | |
875 | * channel to host:port from remote side. | |
876 | */ | |
877 | ||
878 | void | |
879 | channel_request_local_forwarding(u_short port, const char *host, | |
880 | u_short host_port) | |
881 | { | |
882 | int ch, sock, on = 1; | |
883 | struct sockaddr_in sin; | |
884 | extern Options options; | |
885 | struct linger linger; | |
886 | ||
887 | if (strlen(host) > sizeof(channels[0].path) - 1) | |
888 | packet_disconnect("Forward host name too long."); | |
889 | ||
890 | /* Create a port to listen for the host. */ | |
891 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
892 | if (sock < 0) | |
893 | packet_disconnect("socket: %.100s", strerror(errno)); | |
894 | ||
895 | /* Initialize socket address. */ | |
896 | memset(&sin, 0, sizeof(sin)); | |
897 | sin.sin_family = AF_INET; | |
898 | if (options.gateway_ports == 1) | |
899 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
900 | else | |
901 | sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
902 | sin.sin_port = htons(port); | |
903 | ||
904 | /* | |
905 | * Set socket options. We would like the socket to disappear as soon | |
906 | * as it has been closed for whatever reason. | |
907 | */ | |
908 | setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); | |
909 | linger.l_onoff = 1; | |
910 | linger.l_linger = 5; | |
911 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
912 | ||
913 | /* Bind the socket to the address. */ | |
914 | if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) | |
915 | packet_disconnect("bind: %.100s", strerror(errno)); | |
916 | ||
917 | /* Start listening for connections on the socket. */ | |
918 | if (listen(sock, 5) < 0) | |
919 | packet_disconnect("listen: %.100s", strerror(errno)); | |
920 | ||
921 | /* Allocate a channel number for the socket. */ | |
922 | ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, | |
923 | xstrdup("port listener")); | |
924 | strlcpy(channels[ch].path, host, sizeof(channels[ch].path)); | |
925 | channels[ch].host_port = host_port; | |
926 | channels[ch].listening_port = port; | |
927 | } | |
928 | ||
929 | /* | |
930 | * Initiate forwarding of connections to port "port" on remote host through | |
931 | * the secure channel to host:port from local side. | |
932 | */ | |
933 | ||
934 | void | |
935 | channel_request_remote_forwarding(u_short port, const char *host, | |
936 | u_short remote_port) | |
937 | { | |
938 | int payload_len; | |
939 | /* Record locally that connection to this host/port is permitted. */ | |
940 | if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) | |
941 | fatal("channel_request_remote_forwarding: too many forwards"); | |
942 | ||
943 | permitted_opens[num_permitted_opens].host = xstrdup(host); | |
944 | permitted_opens[num_permitted_opens].port = remote_port; | |
945 | num_permitted_opens++; | |
946 | ||
947 | /* Send the forward request to the remote side. */ | |
948 | packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); | |
949 | packet_put_int(port); | |
950 | packet_put_string(host, strlen(host)); | |
951 | packet_put_int(remote_port); | |
952 | packet_send(); | |
953 | packet_write_wait(); | |
954 | ||
955 | /* | |
956 | * Wait for response from the remote side. It will send a disconnect | |
957 | * message on failure, and we will never see it here. | |
958 | */ | |
959 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); | |
960 | } | |
961 | ||
962 | /* | |
963 | * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates | |
964 | * listening for the port, and sends back a success reply (or disconnect | |
965 | * message if there was an error). This never returns if there was an error. | |
966 | */ | |
967 | ||
968 | void | |
969 | channel_input_port_forward_request(int is_root) | |
970 | { | |
971 | u_short port, host_port; | |
972 | char *hostname; | |
973 | ||
974 | /* Get arguments from the packet. */ | |
975 | port = packet_get_int(); | |
976 | hostname = packet_get_string(NULL); | |
977 | host_port = packet_get_int(); | |
978 | ||
979 | /* | |
980 | * Check that an unprivileged user is not trying to forward a | |
981 | * privileged port. | |
982 | */ | |
983 | if (port < IPPORT_RESERVED && !is_root) | |
984 | packet_disconnect("Requested forwarding of port %d but user is not root.", | |
985 | port); | |
986 | ||
987 | /* Initiate forwarding. */ | |
988 | channel_request_local_forwarding(port, hostname, host_port); | |
989 | ||
990 | /* Free the argument string. */ | |
991 | xfree(hostname); | |
992 | } | |
993 | ||
994 | /* | |
995 | * This is called after receiving PORT_OPEN message. This attempts to | |
996 | * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION | |
997 | * or CHANNEL_OPEN_FAILURE. | |
998 | */ | |
999 | ||
1000 | void | |
1001 | channel_input_port_open(int payload_len) | |
1002 | { | |
1003 | int remote_channel, sock, newch, i; | |
1004 | u_short host_port; | |
1005 | struct sockaddr_in sin; | |
1006 | char *host, *originator_string; | |
1007 | struct hostent *hp; | |
1008 | int host_len, originator_len; | |
1009 | ||
1010 | /* Get remote channel number. */ | |
1011 | remote_channel = packet_get_int(); | |
1012 | ||
1013 | /* Get host name to connect to. */ | |
1014 | host = packet_get_string(&host_len); | |
1015 | ||
1016 | /* Get port to connect to. */ | |
1017 | host_port = packet_get_int(); | |
1018 | ||
1019 | /* Get remote originator name. */ | |
1020 | if (have_hostname_in_open) { | |
1021 | originator_string = packet_get_string(&originator_len); | |
1022 | originator_len += 4; /* size of packet_int */ | |
1023 | } else { | |
1024 | originator_string = xstrdup("unknown (remote did not supply name)"); | |
1025 | originator_len = 0; /* no originator supplied */ | |
1026 | } | |
1027 | ||
1028 | packet_integrity_check(payload_len, | |
1029 | 4 + 4 + host_len + 4 + originator_len, | |
1030 | SSH_MSG_PORT_OPEN); | |
1031 | ||
1032 | /* Check if opening that port is permitted. */ | |
1033 | if (!all_opens_permitted) { | |
1034 | /* Go trough all permitted ports. */ | |
1035 | for (i = 0; i < num_permitted_opens; i++) | |
1036 | if (permitted_opens[i].port == host_port && | |
1037 | strcmp(permitted_opens[i].host, host) == 0) | |
1038 | break; | |
1039 | ||
1040 | /* Check if we found the requested port among those permitted. */ | |
1041 | if (i >= num_permitted_opens) { | |
1042 | /* The port is not permitted. */ | |
1043 | log("Received request to connect to %.100s:%d, but the request was denied.", | |
1044 | host, host_port); | |
1045 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1046 | packet_put_int(remote_channel); | |
1047 | packet_send(); | |
1048 | } | |
1049 | } | |
1050 | memset(&sin, 0, sizeof(sin)); | |
1051 | sin.sin_addr.s_addr = inet_addr(host); | |
1052 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { | |
1053 | /* It was a valid numeric host address. */ | |
1054 | sin.sin_family = AF_INET; | |
1055 | } else { | |
1056 | /* Look up the host address from the name servers. */ | |
1057 | hp = gethostbyname(host); | |
1058 | if (!hp) { | |
1059 | error("%.100s: unknown host.", host); | |
1060 | goto fail; | |
1061 | } | |
1062 | if (!hp->h_addr_list[0]) { | |
1063 | error("%.100s: host has no IP address.", host); | |
1064 | goto fail; | |
1065 | } | |
1066 | sin.sin_family = hp->h_addrtype; | |
1067 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
1068 | sizeof(sin.sin_addr)); | |
1069 | } | |
1070 | sin.sin_port = htons(host_port); | |
1071 | ||
1072 | /* Create the socket. */ | |
1073 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1074 | if (sock < 0) { | |
1075 | error("socket: %.100s", strerror(errno)); | |
1076 | goto fail; | |
1077 | } | |
1078 | /* Connect to the host/port. */ | |
1079 | if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1080 | error("connect %.100s:%d: %.100s", host, host_port, | |
1081 | strerror(errno)); | |
1082 | close(sock); | |
1083 | goto fail; | |
1084 | } | |
1085 | /* Successful connection. */ | |
1086 | ||
1087 | /* Allocate a channel for this connection. */ | |
1088 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); | |
1089 | channels[newch].remote_id = remote_channel; | |
1090 | ||
1091 | /* Send a confirmation to the remote host. */ | |
1092 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1093 | packet_put_int(remote_channel); | |
1094 | packet_put_int(newch); | |
1095 | packet_send(); | |
1096 | ||
1097 | /* Free the argument string. */ | |
1098 | xfree(host); | |
1099 | ||
1100 | return; | |
1101 | ||
1102 | fail: | |
1103 | /* Free the argument string. */ | |
1104 | xfree(host); | |
1105 | ||
1106 | /* Send refusal to the remote host. */ | |
1107 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1108 | packet_put_int(remote_channel); | |
1109 | packet_send(); | |
1110 | } | |
1111 | ||
1112 | /* | |
1113 | * Creates an internet domain socket for listening for X11 connections. | |
1114 | * Returns a suitable value for the DISPLAY variable, or NULL if an error | |
1115 | * occurs. | |
1116 | */ | |
1117 | ||
1118 | char * | |
1119 | x11_create_display_inet(int screen_number) | |
1120 | { | |
1121 | extern ServerOptions options; | |
1122 | int display_number, sock; | |
1123 | u_short port; | |
1124 | struct sockaddr_in sin; | |
1125 | char buf[512]; | |
1126 | char hostname[MAXHOSTNAMELEN]; | |
1127 | ||
1128 | for (display_number = options.x11_display_offset; | |
1129 | display_number < MAX_DISPLAYS; | |
1130 | display_number++) { | |
1131 | port = 6000 + display_number; | |
1132 | memset(&sin, 0, sizeof(sin)); | |
1133 | sin.sin_family = AF_INET; | |
1134 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
1135 | sin.sin_port = htons(port); | |
1136 | ||
1137 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
1138 | if (sock < 0) { | |
1139 | error("socket: %.100s", strerror(errno)); | |
1140 | return NULL; | |
1141 | } | |
1142 | if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1143 | debug("bind port %d: %.100s", port, strerror(errno)); | |
1144 | shutdown(sock, SHUT_RDWR); | |
1145 | close(sock); | |
1146 | continue; | |
1147 | } | |
1148 | break; | |
1149 | } | |
1150 | if (display_number >= MAX_DISPLAYS) { | |
1151 | error("Failed to allocate internet-domain X11 display socket."); | |
1152 | return NULL; | |
1153 | } | |
1154 | /* Start listening for connections on the socket. */ | |
1155 | if (listen(sock, 5) < 0) { | |
1156 | error("listen: %.100s", strerror(errno)); | |
1157 | shutdown(sock, SHUT_RDWR); | |
1158 | close(sock); | |
1159 | return NULL; | |
1160 | } | |
1161 | /* Set up a suitable value for the DISPLAY variable. */ | |
1162 | if (gethostname(hostname, sizeof(hostname)) < 0) | |
1163 | fatal("gethostname: %.100s", strerror(errno)); | |
1164 | snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname, | |
1165 | display_number, screen_number); | |
1166 | ||
1167 | /* Allocate a channel for the socket. */ | |
1168 | (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, | |
1169 | xstrdup("X11 inet listener")); | |
1170 | ||
1171 | /* Return a suitable value for the DISPLAY environment variable. */ | |
1172 | return xstrdup(buf); | |
1173 | } | |
1174 | ||
1175 | #ifndef X_UNIX_PATH | |
1176 | #define X_UNIX_PATH "/tmp/.X11-unix/X" | |
1177 | #endif | |
1178 | ||
1179 | static | |
1180 | int | |
1181 | connect_local_xsocket(unsigned int dnr) | |
1182 | { | |
1183 | static const char *const x_sockets[] = { | |
1184 | X_UNIX_PATH "%u", | |
1185 | "/var/X/.X11-unix/X" "%u", | |
1186 | "/usr/spool/sockets/X11/" "%u", | |
1187 | NULL | |
1188 | }; | |
1189 | int sock; | |
1190 | struct sockaddr_un addr; | |
1191 | const char *const * path; | |
1192 | ||
1193 | for (path = x_sockets; *path; ++path) { | |
1194 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1195 | if (sock < 0) | |
1196 | error("socket: %.100s", strerror(errno)); | |
1197 | memset(&addr, 0, sizeof(addr)); | |
1198 | addr.sun_family = AF_UNIX; | |
1199 | snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr); | |
1200 | if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0) | |
1201 | return sock; | |
1202 | close(sock); | |
1203 | } | |
1204 | error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); | |
1205 | return -1; | |
1206 | } | |
1207 | ||
1208 | ||
1209 | /* | |
1210 | * This is called when SSH_SMSG_X11_OPEN is received. The packet contains | |
1211 | * the remote channel number. We should do whatever we want, and respond | |
1212 | * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. | |
1213 | */ | |
1214 | ||
1215 | void | |
1216 | x11_input_open(int payload_len) | |
1217 | { | |
1218 | int remote_channel, display_number, sock, newch; | |
1219 | const char *display; | |
1220 | struct sockaddr_in sin; | |
1221 | char buf[1024], *cp, *remote_host; | |
1222 | struct hostent *hp; | |
1223 | int remote_len; | |
1224 | ||
1225 | /* Get remote channel number. */ | |
1226 | remote_channel = packet_get_int(); | |
1227 | ||
1228 | /* Get remote originator name. */ | |
1229 | if (have_hostname_in_open) { | |
1230 | remote_host = packet_get_string(&remote_len); | |
1231 | remote_len += 4; | |
1232 | } else { | |
1233 | remote_host = xstrdup("unknown (remote did not supply name)"); | |
1234 | remote_len = 0; | |
1235 | } | |
1236 | ||
1237 | debug("Received X11 open request."); | |
1238 | packet_integrity_check(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN); | |
1239 | ||
1240 | /* Try to open a socket for the local X server. */ | |
1241 | display = getenv("DISPLAY"); | |
1242 | if (!display) { | |
1243 | error("DISPLAY not set."); | |
1244 | goto fail; | |
1245 | } | |
1246 | /* | |
1247 | * Now we decode the value of the DISPLAY variable and make a | |
1248 | * connection to the real X server. | |
1249 | */ | |
1250 | ||
1251 | /* | |
1252 | * Check if it is a unix domain socket. Unix domain displays are in | |
1253 | * one of the following formats: unix:d[.s], :d[.s], ::d[.s] | |
1254 | */ | |
1255 | if (strncmp(display, "unix:", 5) == 0 || | |
1256 | display[0] == ':') { | |
1257 | /* Connect to the unix domain socket. */ | |
1258 | if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) { | |
1259 | error("Could not parse display number from DISPLAY: %.100s", | |
1260 | display); | |
1261 | goto fail; | |
1262 | } | |
1263 | /* Create a socket. */ | |
1264 | sock = connect_local_xsocket(display_number); | |
1265 | if (sock < 0) | |
1266 | goto fail; | |
1267 | ||
1268 | /* OK, we now have a connection to the display. */ | |
1269 | goto success; | |
1270 | } | |
1271 | /* | |
1272 | * Connect to an inet socket. The DISPLAY value is supposedly | |
1273 | * hostname:d[.s], where hostname may also be numeric IP address. | |
1274 | */ | |
1275 | strncpy(buf, display, sizeof(buf)); | |
1276 | buf[sizeof(buf) - 1] = 0; | |
1277 | cp = strchr(buf, ':'); | |
1278 | if (!cp) { | |
1279 | error("Could not find ':' in DISPLAY: %.100s", display); | |
1280 | goto fail; | |
1281 | } | |
1282 | *cp = 0; | |
1283 | /* buf now contains the host name. But first we parse the display number. */ | |
1284 | if (sscanf(cp + 1, "%d", &display_number) != 1) { | |
1285 | error("Could not parse display number from DISPLAY: %.100s", | |
1286 | display); | |
1287 | goto fail; | |
1288 | } | |
1289 | /* Try to parse the host name as a numeric IP address. */ | |
1290 | memset(&sin, 0, sizeof(sin)); | |
1291 | sin.sin_addr.s_addr = inet_addr(buf); | |
1292 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { | |
1293 | /* It was a valid numeric host address. */ | |
1294 | sin.sin_family = AF_INET; | |
1295 | } else { | |
1296 | /* Not a numeric IP address. */ | |
1297 | /* Look up the host address from the name servers. */ | |
1298 | hp = gethostbyname(buf); | |
1299 | if (!hp) { | |
1300 | error("%.100s: unknown host.", buf); | |
1301 | goto fail; | |
1302 | } | |
1303 | if (!hp->h_addr_list[0]) { | |
1304 | error("%.100s: host has no IP address.", buf); | |
1305 | goto fail; | |
1306 | } | |
1307 | sin.sin_family = hp->h_addrtype; | |
1308 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
1309 | sizeof(sin.sin_addr)); | |
1310 | } | |
1311 | /* Set port number. */ | |
1312 | sin.sin_port = htons(6000 + display_number); | |
1313 | ||
1314 | /* Create a socket. */ | |
1315 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1316 | if (sock < 0) { | |
1317 | error("socket: %.100s", strerror(errno)); | |
1318 | goto fail; | |
1319 | } | |
1320 | /* Connect it to the display. */ | |
1321 | if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1322 | error("connect %.100s:%d: %.100s", buf, 6000 + display_number, | |
1323 | strerror(errno)); | |
1324 | close(sock); | |
1325 | goto fail; | |
1326 | } | |
1327 | success: | |
1328 | /* We have successfully obtained a connection to the real X display. */ | |
1329 | ||
1330 | /* Allocate a channel for this connection. */ | |
1331 | if (x11_saved_proto == NULL) | |
1332 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); | |
1333 | else | |
1334 | newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host); | |
1335 | channels[newch].remote_id = remote_channel; | |
1336 | ||
1337 | /* Send a confirmation to the remote host. */ | |
1338 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1339 | packet_put_int(remote_channel); | |
1340 | packet_put_int(newch); | |
1341 | packet_send(); | |
1342 | ||
1343 | return; | |
1344 | ||
1345 | fail: | |
1346 | /* Send refusal to the remote host. */ | |
1347 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1348 | packet_put_int(remote_channel); | |
1349 | packet_send(); | |
1350 | } | |
1351 | ||
1352 | /* | |
1353 | * Requests forwarding of X11 connections, generates fake authentication | |
1354 | * data, and enables authentication spoofing. | |
1355 | */ | |
1356 | ||
1357 | void | |
1358 | x11_request_forwarding_with_spoofing(const char *proto, const char *data) | |
1359 | { | |
1360 | unsigned int data_len = (unsigned int) strlen(data) / 2; | |
1361 | unsigned int i, value; | |
1362 | char *new_data; | |
1363 | int screen_number; | |
1364 | const char *cp; | |
1365 | u_int32_t rand = 0; | |
1366 | ||
1367 | cp = getenv("DISPLAY"); | |
1368 | if (cp) | |
1369 | cp = strchr(cp, ':'); | |
1370 | if (cp) | |
1371 | cp = strchr(cp, '.'); | |
1372 | if (cp) | |
1373 | screen_number = atoi(cp + 1); | |
1374 | else | |
1375 | screen_number = 0; | |
1376 | ||
1377 | /* Save protocol name. */ | |
1378 | x11_saved_proto = xstrdup(proto); | |
1379 | ||
1380 | /* | |
1381 | * Extract real authentication data and generate fake data of the | |
1382 | * same length. | |
1383 | */ | |
1384 | x11_saved_data = xmalloc(data_len); | |
1385 | x11_fake_data = xmalloc(data_len); | |
1386 | for (i = 0; i < data_len; i++) { | |
1387 | if (sscanf(data + 2 * i, "%2x", &value) != 1) | |
1388 | fatal("x11_request_forwarding: bad authentication data: %.100s", data); | |
1389 | if (i % 4 == 0) | |
1390 | rand = arc4random(); | |
1391 | x11_saved_data[i] = value; | |
1392 | x11_fake_data[i] = rand & 0xff; | |
1393 | rand >>= 8; | |
1394 | } | |
1395 | x11_saved_data_len = data_len; | |
1396 | x11_fake_data_len = data_len; | |
1397 | ||
1398 | /* Convert the fake data into hex. */ | |
1399 | new_data = xmalloc(2 * data_len + 1); | |
1400 | for (i = 0; i < data_len; i++) | |
1401 | sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]); | |
1402 | ||
1403 | /* Send the request packet. */ | |
1404 | packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); | |
1405 | packet_put_string(proto, strlen(proto)); | |
1406 | packet_put_string(new_data, strlen(new_data)); | |
1407 | packet_put_int(screen_number); | |
1408 | packet_send(); | |
1409 | packet_write_wait(); | |
1410 | xfree(new_data); | |
1411 | } | |
1412 | ||
1413 | /* Sends a message to the server to request authentication fd forwarding. */ | |
1414 | ||
1415 | void | |
1416 | auth_request_forwarding() | |
1417 | { | |
1418 | packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); | |
1419 | packet_send(); | |
1420 | packet_write_wait(); | |
1421 | } | |
1422 | ||
1423 | /* | |
1424 | * Returns the name of the forwarded authentication socket. Returns NULL if | |
1425 | * there is no forwarded authentication socket. The returned value points to | |
1426 | * a static buffer. | |
1427 | */ | |
1428 | ||
1429 | char * | |
1430 | auth_get_socket_name() | |
1431 | { | |
1432 | return channel_forwarded_auth_socket_name; | |
1433 | } | |
1434 | ||
1435 | /* removes the agent forwarding socket */ | |
1436 | ||
1437 | void | |
1438 | cleanup_socket(void) | |
1439 | { | |
1440 | remove(channel_forwarded_auth_socket_name); | |
1441 | rmdir(channel_forwarded_auth_socket_dir); | |
1442 | } | |
1443 | ||
1444 | /* | |
1445 | * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. | |
1446 | * This starts forwarding authentication requests. | |
1447 | */ | |
1448 | ||
1449 | void | |
1450 | auth_input_request_forwarding(struct passwd * pw) | |
1451 | { | |
1452 | int sock, newch; | |
1453 | struct sockaddr_un sunaddr; | |
1454 | ||
1455 | if (auth_get_socket_name() != NULL) | |
1456 | fatal("Protocol error: authentication forwarding requested twice."); | |
1457 | ||
1458 | /* Temporarily drop privileged uid for mkdir/bind. */ | |
1459 | temporarily_use_uid(pw->pw_uid); | |
1460 | ||
1461 | /* Allocate a buffer for the socket name, and format the name. */ | |
1462 | channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); | |
1463 | channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); | |
1464 | strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); | |
1465 | ||
1466 | /* Create private directory for socket */ | |
1467 | if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) | |
1468 | packet_disconnect("mkdtemp: %.100s", strerror(errno)); | |
1469 | snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d", | |
1470 | channel_forwarded_auth_socket_dir, (int) getpid()); | |
1471 | ||
1472 | if (atexit(cleanup_socket) < 0) { | |
1473 | int saved = errno; | |
1474 | cleanup_socket(); | |
1475 | packet_disconnect("socket: %.100s", strerror(saved)); | |
1476 | } | |
1477 | /* Create the socket. */ | |
1478 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1479 | if (sock < 0) | |
1480 | packet_disconnect("socket: %.100s", strerror(errno)); | |
1481 | ||
1482 | /* Bind it to the name. */ | |
1483 | memset(&sunaddr, 0, sizeof(sunaddr)); | |
1484 | sunaddr.sun_family = AF_UNIX; | |
1485 | strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name, | |
1486 | sizeof(sunaddr.sun_path)); | |
1487 | ||
1488 | if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) | |
1489 | packet_disconnect("bind: %.100s", strerror(errno)); | |
1490 | ||
1491 | /* Restore the privileged uid. */ | |
1492 | restore_uid(); | |
1493 | ||
1494 | /* Start listening on the socket. */ | |
1495 | if (listen(sock, 5) < 0) | |
1496 | packet_disconnect("listen: %.100s", strerror(errno)); | |
1497 | ||
1498 | /* Allocate a channel for the authentication agent socket. */ | |
1499 | newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, | |
1500 | xstrdup("auth socket")); | |
1501 | strlcpy(channels[newch].path, channel_forwarded_auth_socket_name, | |
1502 | sizeof(channels[newch].path)); | |
1503 | } | |
1504 | ||
1505 | /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ | |
1506 | ||
1507 | void | |
1508 | auth_input_open_request() | |
1509 | { | |
1510 | int remch, sock, newch; | |
1511 | char *dummyname; | |
1512 | ||
1513 | /* Read the remote channel number from the message. */ | |
1514 | remch = packet_get_int(); | |
1515 | ||
1516 | /* | |
1517 | * Get a connection to the local authentication agent (this may again | |
1518 | * get forwarded). | |
1519 | */ | |
1520 | sock = ssh_get_authentication_socket(); | |
1521 | ||
1522 | /* | |
1523 | * If we could not connect the agent, send an error message back to | |
1524 | * the server. This should never happen unless the agent dies, | |
1525 | * because authentication forwarding is only enabled if we have an | |
1526 | * agent. | |
1527 | */ | |
1528 | if (sock < 0) { | |
1529 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1530 | packet_put_int(remch); | |
1531 | packet_send(); | |
1532 | return; | |
1533 | } | |
1534 | debug("Forwarding authentication connection."); | |
1535 | ||
1536 | /* | |
1537 | * Dummy host name. This will be freed when the channel is freed; it | |
1538 | * will still be valid in the packet_put_string below since the | |
1539 | * channel cannot yet be freed at that point. | |
1540 | */ | |
1541 | dummyname = xstrdup("authentication agent connection"); | |
1542 | ||
1543 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); | |
1544 | channels[newch].remote_id = remch; | |
1545 | ||
1546 | /* Send a confirmation to the remote host. */ | |
1547 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1548 | packet_put_int(remch); | |
1549 | packet_put_int(newch); | |
1550 | packet_send(); | |
1551 | } |