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Commit | Line | Data |
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8efc0c15 | 1 | /* |
5260325f | 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 | */ | |
8efc0c15 | 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" | |
6fa724bc | 27 | #include "readconf.h" |
8efc0c15 | 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 | /* Pointer to an array containing all allocated channels. The array is | |
41 | dynamically extended as needed. */ | |
42 | static Channel *channels = NULL; | |
43 | ||
44 | /* Size of the channel array. All slots of the array must always be | |
45 | initialized (at least the type field); unused slots are marked with | |
46 | type SSH_CHANNEL_FREE. */ | |
47 | static int channels_alloc = 0; | |
48 | ||
49 | /* Maximum file descriptor value used in any of the channels. This is updated | |
50 | in channel_allocate. */ | |
51 | static int channel_max_fd_value = 0; | |
52 | ||
53 | /* Name and directory of socket for authentication agent forwarding. */ | |
54 | static char *channel_forwarded_auth_socket_name = NULL; | |
5260325f | 55 | static char *channel_forwarded_auth_socket_dir = NULL; |
8efc0c15 | 56 | |
57 | /* Saved X11 authentication protocol name. */ | |
58 | char *x11_saved_proto = NULL; | |
59 | ||
60 | /* Saved X11 authentication data. This is the real data. */ | |
61 | char *x11_saved_data = NULL; | |
62 | unsigned int x11_saved_data_len = 0; | |
63 | ||
64 | /* Fake X11 authentication data. This is what the server will be sending | |
65 | us; we should replace any occurrences of this by the real data. */ | |
66 | char *x11_fake_data = NULL; | |
67 | unsigned int x11_fake_data_len; | |
68 | ||
69 | /* Data structure for storing which hosts are permitted for forward requests. | |
70 | The local sides of any remote forwards are stored in this array to prevent | |
71 | a corrupt remote server from accessing arbitrary TCP/IP ports on our | |
72 | local network (which might be behind a firewall). */ | |
5260325f | 73 | typedef struct { |
74 | char *host; /* Host name. */ | |
75 | int port; /* Port number. */ | |
8efc0c15 | 76 | } ForwardPermission; |
77 | ||
78 | /* List of all permitted host/port pairs to connect. */ | |
79 | static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION]; | |
80 | /* Number of permitted host/port pairs in the array. */ | |
81 | static int num_permitted_opens = 0; | |
82 | /* If this is true, all opens are permitted. This is the case on the | |
83 | server on which we have to trust the client anyway, and the user could | |
84 | do anything after logging in anyway. */ | |
85 | static int all_opens_permitted = 0; | |
86 | ||
87 | /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */ | |
88 | static int have_hostname_in_open = 0; | |
89 | ||
90 | /* Sets specific protocol options. */ | |
91 | ||
5260325f | 92 | void |
93 | channel_set_options(int hostname_in_open) | |
8efc0c15 | 94 | { |
5260325f | 95 | have_hostname_in_open = hostname_in_open; |
8efc0c15 | 96 | } |
97 | ||
98 | /* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually | |
99 | called by the server, because the user could connect to any port anyway, | |
100 | and the server has no way to know but to trust the client anyway. */ | |
101 | ||
5260325f | 102 | void |
103 | channel_permit_all_opens() | |
8efc0c15 | 104 | { |
5260325f | 105 | all_opens_permitted = 1; |
8efc0c15 | 106 | } |
107 | ||
5260325f | 108 | /* Allocate a new channel object and set its type and socket. |
8efc0c15 | 109 | This will cause remote_name to be freed. */ |
110 | ||
5260325f | 111 | int |
112 | channel_allocate(int type, int sock, char *remote_name) | |
8efc0c15 | 113 | { |
5260325f | 114 | int i, found; |
115 | Channel *c; | |
116 | ||
117 | /* Update the maximum file descriptor value. */ | |
118 | if (sock > channel_max_fd_value) | |
119 | channel_max_fd_value = sock; | |
120 | ||
121 | /* Do initial allocation if this is the first call. */ | |
122 | if (channels_alloc == 0) { | |
123 | channels_alloc = 10; | |
124 | channels = xmalloc(channels_alloc * sizeof(Channel)); | |
125 | for (i = 0; i < channels_alloc; i++) | |
126 | channels[i].type = SSH_CHANNEL_FREE; | |
127 | ||
128 | /* Kludge: arrange a call to channel_stop_listening if we | |
129 | terminate with fatal(). */ | |
130 | fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL); | |
131 | } | |
132 | /* Try to find a free slot where to put the new channel. */ | |
133 | for (found = -1, i = 0; i < channels_alloc; i++) | |
134 | if (channels[i].type == SSH_CHANNEL_FREE) { | |
135 | /* Found a free slot. */ | |
136 | found = i; | |
137 | break; | |
138 | } | |
139 | if (found == -1) { | |
140 | /* There are no free slots. Take last+1 slot and expand | |
141 | the array. */ | |
142 | found = channels_alloc; | |
143 | channels_alloc += 10; | |
144 | debug("channel: expanding %d", channels_alloc); | |
145 | channels = xrealloc(channels, channels_alloc * sizeof(Channel)); | |
146 | for (i = found; i < channels_alloc; i++) | |
147 | channels[i].type = SSH_CHANNEL_FREE; | |
148 | } | |
149 | /* Initialize and return new channel number. */ | |
150 | c = &channels[found]; | |
151 | buffer_init(&c->input); | |
152 | buffer_init(&c->output); | |
153 | chan_init_iostates(c); | |
154 | c->self = found; | |
155 | c->type = type; | |
156 | c->sock = sock; | |
157 | c->remote_id = -1; | |
158 | c->remote_name = remote_name; | |
159 | debug("channel %d: new [%s]", found, remote_name); | |
160 | return found; | |
8efc0c15 | 161 | } |
162 | ||
163 | /* Free the channel and close its socket. */ | |
164 | ||
5260325f | 165 | void |
166 | channel_free(int channel) | |
8efc0c15 | 167 | { |
5260325f | 168 | if (channel < 0 || channel >= channels_alloc || |
169 | channels[channel].type == SSH_CHANNEL_FREE) | |
170 | packet_disconnect("channel free: bad local channel %d", channel); | |
171 | ||
172 | if (compat13) | |
173 | shutdown(channels[channel].sock, SHUT_RDWR); | |
174 | close(channels[channel].sock); | |
175 | buffer_free(&channels[channel].input); | |
176 | buffer_free(&channels[channel].output); | |
177 | channels[channel].type = SSH_CHANNEL_FREE; | |
178 | if (channels[channel].remote_name) { | |
179 | xfree(channels[channel].remote_name); | |
180 | channels[channel].remote_name = NULL; | |
181 | } | |
8efc0c15 | 182 | } |
183 | ||
184 | /* This is called just before select() to add any bits relevant to | |
185 | channels in the select bitmasks. */ | |
186 | ||
5260325f | 187 | void |
188 | channel_prepare_select(fd_set * readset, fd_set * writeset) | |
8efc0c15 | 189 | { |
5260325f | 190 | int i; |
191 | Channel *ch; | |
192 | unsigned char *ucp; | |
193 | unsigned int proto_len, data_len; | |
194 | ||
195 | for (i = 0; i < channels_alloc; i++) { | |
196 | ch = &channels[i]; | |
197 | redo: | |
198 | switch (ch->type) { | |
199 | case SSH_CHANNEL_X11_LISTENER: | |
200 | case SSH_CHANNEL_PORT_LISTENER: | |
201 | case SSH_CHANNEL_AUTH_SOCKET: | |
202 | FD_SET(ch->sock, readset); | |
203 | break; | |
204 | ||
205 | case SSH_CHANNEL_OPEN: | |
206 | if (compat13) { | |
207 | if (buffer_len(&ch->input) < packet_get_maxsize()) | |
208 | FD_SET(ch->sock, readset); | |
209 | if (buffer_len(&ch->output) > 0) | |
210 | FD_SET(ch->sock, writeset); | |
211 | break; | |
212 | } | |
213 | /* test whether sockets are 'alive' for read/write */ | |
214 | if (ch->istate == CHAN_INPUT_OPEN) | |
215 | if (buffer_len(&ch->input) < packet_get_maxsize()) | |
216 | FD_SET(ch->sock, readset); | |
217 | if (ch->ostate == CHAN_OUTPUT_OPEN || | |
218 | ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { | |
219 | if (buffer_len(&ch->output) > 0) { | |
220 | FD_SET(ch->sock, writeset); | |
221 | } else if (ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { | |
222 | chan_obuf_empty(ch); | |
223 | } | |
224 | } | |
225 | break; | |
226 | ||
227 | case SSH_CHANNEL_INPUT_DRAINING: | |
228 | if (!compat13) | |
229 | fatal("cannot happen: IN_DRAIN"); | |
230 | if (buffer_len(&ch->input) == 0) { | |
231 | packet_start(SSH_MSG_CHANNEL_CLOSE); | |
232 | packet_put_int(ch->remote_id); | |
233 | packet_send(); | |
234 | ch->type = SSH_CHANNEL_CLOSED; | |
235 | debug("Closing channel %d after input drain.", i); | |
236 | break; | |
237 | } | |
238 | break; | |
239 | ||
240 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
241 | if (!compat13) | |
242 | fatal("cannot happen: OUT_DRAIN"); | |
243 | if (buffer_len(&ch->output) == 0) { | |
244 | channel_free(i); | |
245 | break; | |
246 | } | |
247 | FD_SET(ch->sock, writeset); | |
248 | break; | |
249 | ||
250 | case SSH_CHANNEL_X11_OPEN: | |
251 | /* This is a special state for X11 authentication | |
252 | spoofing. An opened X11 connection (when | |
253 | authentication spoofing is being done) remains | |
254 | in this state until the first packet has been | |
255 | completely read. The authentication data in | |
256 | that packet is then substituted by the real | |
257 | data if it matches the fake data, and the | |
258 | channel is put into normal mode. */ | |
259 | ||
260 | /* Check if the fixed size part of the packet is in buffer. */ | |
261 | if (buffer_len(&ch->output) < 12) | |
262 | break; | |
263 | ||
264 | /* Parse the lengths of variable-length fields. */ | |
265 | ucp = (unsigned char *) buffer_ptr(&ch->output); | |
266 | if (ucp[0] == 0x42) { /* Byte order MSB first. */ | |
267 | proto_len = 256 * ucp[6] + ucp[7]; | |
268 | data_len = 256 * ucp[8] + ucp[9]; | |
269 | } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */ | |
270 | proto_len = ucp[6] + 256 * ucp[7]; | |
271 | data_len = ucp[8] + 256 * ucp[9]; | |
272 | } else { | |
273 | debug("Initial X11 packet contains bad byte order byte: 0x%x", | |
274 | ucp[0]); | |
275 | ch->type = SSH_CHANNEL_OPEN; | |
276 | goto reject; | |
277 | } | |
278 | ||
279 | /* Check if the whole packet is in buffer. */ | |
280 | if (buffer_len(&ch->output) < | |
281 | 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) | |
282 | break; | |
283 | ||
284 | /* Check if authentication protocol matches. */ | |
285 | if (proto_len != strlen(x11_saved_proto) || | |
286 | memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) { | |
287 | debug("X11 connection uses different authentication protocol."); | |
288 | ch->type = SSH_CHANNEL_OPEN; | |
289 | goto reject; | |
290 | } | |
291 | /* Check if authentication data matches our fake data. */ | |
292 | if (data_len != x11_fake_data_len || | |
293 | memcmp(ucp + 12 + ((proto_len + 3) & ~3), | |
294 | x11_fake_data, x11_fake_data_len) != 0) { | |
295 | debug("X11 auth data does not match fake data."); | |
296 | ch->type = SSH_CHANNEL_OPEN; | |
297 | goto reject; | |
298 | } | |
299 | /* Check fake data length */ | |
300 | if (x11_fake_data_len != x11_saved_data_len) { | |
301 | error("X11 fake_data_len %d != saved_data_len %d", | |
302 | x11_fake_data_len, x11_saved_data_len); | |
303 | ch->type = SSH_CHANNEL_OPEN; | |
304 | goto reject; | |
305 | } | |
306 | /* Received authentication protocol and data match | |
307 | our fake data. Substitute the fake data with | |
308 | real data. */ | |
309 | memcpy(ucp + 12 + ((proto_len + 3) & ~3), | |
310 | x11_saved_data, x11_saved_data_len); | |
311 | ||
312 | /* Start normal processing for the channel. */ | |
313 | ch->type = SSH_CHANNEL_OPEN; | |
314 | goto redo; | |
315 | ||
8efc0c15 | 316 | reject: |
5260325f | 317 | /* We have received an X11 connection that has bad |
318 | authentication information. */ | |
319 | log("X11 connection rejected because of wrong authentication.\r\n"); | |
320 | buffer_clear(&ch->input); | |
321 | buffer_clear(&ch->output); | |
322 | if (compat13) { | |
323 | close(ch->sock); | |
324 | ch->sock = -1; | |
325 | ch->type = SSH_CHANNEL_CLOSED; | |
326 | packet_start(SSH_MSG_CHANNEL_CLOSE); | |
327 | packet_put_int(ch->remote_id); | |
328 | packet_send(); | |
329 | } else { | |
330 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); | |
331 | chan_read_failed(ch); | |
332 | chan_write_failed(ch); | |
333 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); | |
334 | } | |
335 | break; | |
336 | ||
337 | case SSH_CHANNEL_FREE: | |
338 | default: | |
339 | continue; | |
340 | } | |
8efc0c15 | 341 | } |
8efc0c15 | 342 | } |
343 | ||
344 | /* After select, perform any appropriate operations for channels which | |
345 | have events pending. */ | |
346 | ||
5260325f | 347 | void |
348 | channel_after_select(fd_set * readset, fd_set * writeset) | |
8efc0c15 | 349 | { |
5260325f | 350 | struct sockaddr addr; |
351 | int addrlen, newsock, i, newch, len; | |
352 | Channel *ch; | |
353 | char buf[16384], *remote_hostname; | |
354 | ||
355 | /* Loop over all channels... */ | |
356 | for (i = 0; i < channels_alloc; i++) { | |
357 | ch = &channels[i]; | |
358 | switch (ch->type) { | |
359 | case SSH_CHANNEL_X11_LISTENER: | |
360 | /* This is our fake X11 server socket. */ | |
361 | if (FD_ISSET(ch->sock, readset)) { | |
362 | debug("X11 connection requested."); | |
363 | addrlen = sizeof(addr); | |
364 | newsock = accept(ch->sock, &addr, &addrlen); | |
365 | if (newsock < 0) { | |
366 | error("accept: %.100s", strerror(errno)); | |
367 | break; | |
368 | } | |
369 | remote_hostname = get_remote_hostname(newsock); | |
370 | snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", | |
371 | remote_hostname, get_peer_port(newsock)); | |
372 | xfree(remote_hostname); | |
373 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
374 | xstrdup(buf)); | |
375 | packet_start(SSH_SMSG_X11_OPEN); | |
376 | packet_put_int(newch); | |
377 | if (have_hostname_in_open) | |
378 | packet_put_string(buf, strlen(buf)); | |
379 | packet_send(); | |
380 | } | |
381 | break; | |
382 | ||
383 | case SSH_CHANNEL_PORT_LISTENER: | |
384 | /* This socket is listening for connections to a | |
385 | forwarded TCP/IP port. */ | |
386 | if (FD_ISSET(ch->sock, readset)) { | |
387 | debug("Connection to port %d forwarding to %.100s:%d requested.", | |
388 | ch->listening_port, ch->path, ch->host_port); | |
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, "listen port %d:%.100s:%d, connect from %.200s:%d", | |
397 | ch->listening_port, ch->path, ch->host_port, | |
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_MSG_PORT_OPEN); | |
403 | packet_put_int(newch); | |
404 | packet_put_string(ch->path, strlen(ch->path)); | |
405 | packet_put_int(ch->host_port); | |
406 | if (have_hostname_in_open) | |
407 | packet_put_string(buf, strlen(buf)); | |
408 | packet_send(); | |
409 | } | |
410 | break; | |
411 | ||
412 | case SSH_CHANNEL_AUTH_SOCKET: | |
413 | /* This is the authentication agent socket | |
414 | listening for connections from clients. */ | |
415 | if (FD_ISSET(ch->sock, readset)) { | |
416 | int nchan; | |
417 | len = sizeof(addr); | |
418 | newsock = accept(ch->sock, &addr, &len); | |
419 | if (newsock < 0) { | |
420 | error("accept from auth socket: %.100s", strerror(errno)); | |
421 | break; | |
422 | } | |
423 | nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
424 | xstrdup("accepted auth socket")); | |
425 | packet_start(SSH_SMSG_AGENT_OPEN); | |
426 | packet_put_int(nchan); | |
427 | packet_send(); | |
428 | } | |
429 | break; | |
430 | ||
431 | case SSH_CHANNEL_OPEN: | |
432 | /* This is an open two-way communication channel. | |
433 | It is not of interest to us at this point what | |
434 | kind of data is being transmitted. */ | |
435 | ||
436 | /* Read available incoming data and append it to | |
437 | buffer; shutdown socket, if read or write | |
438 | failes */ | |
439 | if (FD_ISSET(ch->sock, readset)) { | |
440 | len = read(ch->sock, buf, sizeof(buf)); | |
441 | if (len <= 0) { | |
442 | if (compat13) { | |
443 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
444 | ch->type = SSH_CHANNEL_INPUT_DRAINING; | |
445 | debug("Channel %d status set to input draining.", i); | |
446 | } else { | |
447 | chan_read_failed(ch); | |
448 | } | |
449 | break; | |
450 | } | |
451 | buffer_append(&ch->input, buf, len); | |
452 | } | |
453 | /* Send buffered output data to the socket. */ | |
454 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) { | |
455 | len = write(ch->sock, buffer_ptr(&ch->output), | |
456 | buffer_len(&ch->output)); | |
457 | if (len <= 0) { | |
458 | if (compat13) { | |
459 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
460 | debug("Channel %d status set to input draining.", i); | |
461 | ch->type = SSH_CHANNEL_INPUT_DRAINING; | |
462 | } else { | |
463 | chan_write_failed(ch); | |
464 | } | |
465 | break; | |
466 | } | |
467 | buffer_consume(&ch->output, len); | |
468 | } | |
469 | break; | |
470 | ||
471 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
472 | if (!compat13) | |
473 | fatal("cannot happen: OUT_DRAIN"); | |
474 | /* Send buffered output data to the socket. */ | |
475 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) { | |
476 | len = write(ch->sock, buffer_ptr(&ch->output), | |
477 | buffer_len(&ch->output)); | |
478 | if (len <= 0) | |
479 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
480 | else | |
481 | buffer_consume(&ch->output, len); | |
482 | } | |
483 | break; | |
484 | ||
485 | case SSH_CHANNEL_X11_OPEN: | |
486 | case SSH_CHANNEL_FREE: | |
487 | default: | |
488 | continue; | |
8efc0c15 | 489 | } |
8efc0c15 | 490 | } |
8efc0c15 | 491 | } |
492 | ||
493 | /* If there is data to send to the connection, send some of it now. */ | |
494 | ||
5260325f | 495 | void |
496 | channel_output_poll() | |
8efc0c15 | 497 | { |
5260325f | 498 | int len, i; |
499 | Channel *ch; | |
500 | ||
501 | for (i = 0; i < channels_alloc; i++) { | |
502 | ch = &channels[i]; | |
503 | /* We are only interested in channels that can have | |
504 | buffered incoming data. */ | |
505 | if (ch->type != SSH_CHANNEL_OPEN && | |
506 | ch->type != SSH_CHANNEL_INPUT_DRAINING) | |
507 | continue; | |
508 | ||
509 | /* Get the amount of buffered data for this channel. */ | |
510 | len = buffer_len(&ch->input); | |
511 | if (len > 0) { | |
512 | /* Send some data for the other side over the | |
513 | secure connection. */ | |
514 | if (packet_is_interactive()) { | |
515 | if (len > 1024) | |
516 | len = 512; | |
517 | } else { | |
518 | /* Keep the packets at reasonable size. */ | |
519 | if (len > 16384) | |
520 | len = 16384; | |
521 | } | |
522 | packet_start(SSH_MSG_CHANNEL_DATA); | |
523 | packet_put_int(ch->remote_id); | |
524 | packet_put_string(buffer_ptr(&ch->input), len); | |
525 | packet_send(); | |
526 | buffer_consume(&ch->input, len); | |
527 | } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) { | |
528 | if (compat13) | |
529 | fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); | |
530 | /* input-buffer is empty and read-socket shutdown: | |
531 | tell peer, that we will not send more data: | |
532 | send IEOF */ | |
533 | chan_ibuf_empty(ch); | |
534 | } | |
8efc0c15 | 535 | } |
8efc0c15 | 536 | } |
537 | ||
538 | /* This is called when a packet of type CHANNEL_DATA has just been received. | |
539 | The message type has already been consumed, but channel number and data | |
540 | is still there. */ | |
541 | ||
5260325f | 542 | void |
543 | channel_input_data(int payload_len) | |
8efc0c15 | 544 | { |
5260325f | 545 | int channel; |
546 | char *data; | |
547 | unsigned int data_len; | |
548 | ||
549 | /* Get the channel number and verify it. */ | |
550 | channel = packet_get_int(); | |
551 | if (channel < 0 || channel >= channels_alloc || | |
552 | channels[channel].type == SSH_CHANNEL_FREE) | |
553 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
554 | ||
555 | /* Ignore any data for non-open channels (might happen on close) */ | |
556 | if (channels[channel].type != SSH_CHANNEL_OPEN && | |
557 | channels[channel].type != SSH_CHANNEL_X11_OPEN) | |
558 | return; | |
559 | ||
560 | /* Get the data. */ | |
561 | data = packet_get_string(&data_len); | |
562 | packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA); | |
563 | buffer_append(&channels[channel].output, data, data_len); | |
564 | xfree(data); | |
8efc0c15 | 565 | } |
566 | ||
567 | /* Returns true if no channel has too much buffered data, and false if | |
568 | one or more channel is overfull. */ | |
569 | ||
5260325f | 570 | int |
571 | channel_not_very_much_buffered_data() | |
8efc0c15 | 572 | { |
5260325f | 573 | unsigned int i; |
574 | Channel *ch; | |
575 | ||
576 | for (i = 0; i < channels_alloc; i++) { | |
577 | ch = &channels[i]; | |
578 | switch (ch->type) { | |
579 | case SSH_CHANNEL_X11_LISTENER: | |
580 | case SSH_CHANNEL_PORT_LISTENER: | |
581 | case SSH_CHANNEL_AUTH_SOCKET: | |
582 | continue; | |
583 | case SSH_CHANNEL_OPEN: | |
584 | if (buffer_len(&ch->input) > packet_get_maxsize()) | |
585 | return 0; | |
586 | if (buffer_len(&ch->output) > packet_get_maxsize()) | |
587 | return 0; | |
588 | continue; | |
589 | case SSH_CHANNEL_INPUT_DRAINING: | |
590 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
591 | case SSH_CHANNEL_X11_OPEN: | |
592 | case SSH_CHANNEL_FREE: | |
593 | default: | |
594 | continue; | |
595 | } | |
8efc0c15 | 596 | } |
5260325f | 597 | return 1; |
8efc0c15 | 598 | } |
599 | ||
600 | /* This is called after receiving CHANNEL_CLOSE/IEOF. */ | |
601 | ||
5260325f | 602 | void |
603 | channel_input_close() | |
8efc0c15 | 604 | { |
5260325f | 605 | int channel; |
606 | ||
607 | /* Get the channel number and verify it. */ | |
608 | channel = packet_get_int(); | |
609 | if (channel < 0 || channel >= channels_alloc || | |
610 | channels[channel].type == SSH_CHANNEL_FREE) | |
611 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
612 | ||
613 | if (!compat13) { | |
614 | /* proto version 1.5 overloads CLOSE with IEOF */ | |
615 | chan_rcvd_ieof(&channels[channel]); | |
616 | return; | |
617 | } | |
618 | /* Send a confirmation that we have closed the channel and no more | |
619 | data is coming for it. */ | |
620 | packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); | |
621 | packet_put_int(channels[channel].remote_id); | |
622 | packet_send(); | |
623 | ||
624 | /* If the channel is in closed state, we have sent a close | |
625 | request, and the other side will eventually respond with a | |
626 | confirmation. Thus, we cannot free the channel here, because | |
627 | then there would be no-one to receive the confirmation. The | |
628 | channel gets freed when the confirmation arrives. */ | |
629 | if (channels[channel].type != SSH_CHANNEL_CLOSED) { | |
630 | /* Not a closed channel - mark it as draining, which will | |
631 | cause it to be freed later. */ | |
632 | buffer_consume(&channels[channel].input, | |
633 | buffer_len(&channels[channel].input)); | |
634 | channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; | |
635 | } | |
8efc0c15 | 636 | } |
637 | ||
638 | /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ | |
639 | ||
5260325f | 640 | void |
641 | channel_input_close_confirmation() | |
8efc0c15 | 642 | { |
5260325f | 643 | int channel; |
644 | ||
645 | /* Get the channel number and verify it. */ | |
646 | channel = packet_get_int(); | |
647 | if (channel < 0 || channel >= channels_alloc) | |
648 | packet_disconnect("Received close confirmation for out-of-range channel %d.", | |
649 | channel); | |
650 | ||
651 | if (!compat13) { | |
652 | /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ | |
653 | chan_rcvd_oclose(&channels[channel]); | |
654 | return; | |
655 | } | |
656 | if (channels[channel].type != SSH_CHANNEL_CLOSED) | |
657 | packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", | |
658 | channel, channels[channel].type); | |
659 | ||
660 | /* Free the channel. */ | |
661 | channel_free(channel); | |
8efc0c15 | 662 | } |
663 | ||
664 | /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ | |
665 | ||
5260325f | 666 | void |
667 | channel_input_open_confirmation() | |
8efc0c15 | 668 | { |
5260325f | 669 | int channel, remote_channel; |
670 | ||
671 | /* Get the channel number and verify it. */ | |
672 | channel = packet_get_int(); | |
673 | if (channel < 0 || channel >= channels_alloc || | |
674 | channels[channel].type != SSH_CHANNEL_OPENING) | |
675 | packet_disconnect("Received open confirmation for non-opening channel %d.", | |
676 | channel); | |
677 | ||
678 | /* Get remote side's id for this channel. */ | |
679 | remote_channel = packet_get_int(); | |
680 | ||
681 | /* Record the remote channel number and mark that the channel is | |
682 | now open. */ | |
683 | channels[channel].remote_id = remote_channel; | |
684 | channels[channel].type = SSH_CHANNEL_OPEN; | |
8efc0c15 | 685 | } |
686 | ||
687 | /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ | |
688 | ||
5260325f | 689 | void |
690 | channel_input_open_failure() | |
8efc0c15 | 691 | { |
5260325f | 692 | int channel; |
693 | ||
694 | /* Get the channel number and verify it. */ | |
695 | channel = packet_get_int(); | |
696 | if (channel < 0 || channel >= channels_alloc || | |
697 | channels[channel].type != SSH_CHANNEL_OPENING) | |
698 | packet_disconnect("Received open failure for non-opening channel %d.", | |
699 | channel); | |
700 | ||
701 | /* Free the channel. This will also close the socket. */ | |
702 | channel_free(channel); | |
8efc0c15 | 703 | } |
704 | ||
705 | /* Stops listening for channels, and removes any unix domain sockets that | |
706 | we might have. */ | |
707 | ||
5260325f | 708 | void |
709 | channel_stop_listening() | |
8efc0c15 | 710 | { |
5260325f | 711 | int i; |
712 | for (i = 0; i < channels_alloc; i++) { | |
713 | switch (channels[i].type) { | |
714 | case SSH_CHANNEL_AUTH_SOCKET: | |
715 | close(channels[i].sock); | |
716 | remove(channels[i].path); | |
717 | channel_free(i); | |
718 | break; | |
719 | case SSH_CHANNEL_PORT_LISTENER: | |
720 | case SSH_CHANNEL_X11_LISTENER: | |
721 | close(channels[i].sock); | |
722 | channel_free(i); | |
723 | break; | |
724 | default: | |
725 | break; | |
726 | } | |
8efc0c15 | 727 | } |
8efc0c15 | 728 | } |
729 | ||
730 | /* Closes the sockets of all channels. This is used to close extra file | |
731 | descriptors after a fork. */ | |
732 | ||
5260325f | 733 | void |
734 | channel_close_all() | |
8efc0c15 | 735 | { |
5260325f | 736 | int i; |
737 | for (i = 0; i < channels_alloc; i++) { | |
738 | if (channels[i].type != SSH_CHANNEL_FREE) | |
739 | close(channels[i].sock); | |
740 | } | |
8efc0c15 | 741 | } |
742 | ||
743 | /* Returns the maximum file descriptor number used by the channels. */ | |
744 | ||
5260325f | 745 | int |
746 | channel_max_fd() | |
8efc0c15 | 747 | { |
5260325f | 748 | return channel_max_fd_value; |
8efc0c15 | 749 | } |
750 | ||
751 | /* Returns true if any channel is still open. */ | |
752 | ||
5260325f | 753 | int |
754 | channel_still_open() | |
8efc0c15 | 755 | { |
5260325f | 756 | unsigned int i; |
757 | for (i = 0; i < channels_alloc; i++) | |
758 | switch (channels[i].type) { | |
759 | case SSH_CHANNEL_FREE: | |
760 | case SSH_CHANNEL_X11_LISTENER: | |
761 | case SSH_CHANNEL_PORT_LISTENER: | |
762 | case SSH_CHANNEL_CLOSED: | |
763 | case SSH_CHANNEL_AUTH_SOCKET: | |
764 | continue; | |
765 | case SSH_CHANNEL_OPENING: | |
766 | case SSH_CHANNEL_OPEN: | |
767 | case SSH_CHANNEL_X11_OPEN: | |
768 | return 1; | |
769 | case SSH_CHANNEL_INPUT_DRAINING: | |
770 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
771 | if (!compat13) | |
772 | fatal("cannot happen: OUT_DRAIN"); | |
773 | return 1; | |
774 | default: | |
775 | fatal("channel_still_open: bad channel type %d", channels[i].type); | |
776 | /* NOTREACHED */ | |
777 | } | |
778 | return 0; | |
8efc0c15 | 779 | } |
780 | ||
781 | /* Returns a message describing the currently open forwarded | |
782 | connections, suitable for sending to the client. The message | |
783 | contains crlf pairs for newlines. */ | |
784 | ||
5260325f | 785 | char * |
786 | channel_open_message() | |
8efc0c15 | 787 | { |
5260325f | 788 | Buffer buffer; |
789 | int i; | |
790 | char buf[512], *cp; | |
791 | ||
792 | buffer_init(&buffer); | |
793 | snprintf(buf, sizeof buf, "The following connections are open:\r\n"); | |
8efc0c15 | 794 | buffer_append(&buffer, buf, strlen(buf)); |
5260325f | 795 | for (i = 0; i < channels_alloc; i++) { |
796 | Channel *c = &channels[i]; | |
797 | switch (c->type) { | |
798 | case SSH_CHANNEL_FREE: | |
799 | case SSH_CHANNEL_X11_LISTENER: | |
800 | case SSH_CHANNEL_PORT_LISTENER: | |
801 | case SSH_CHANNEL_CLOSED: | |
802 | case SSH_CHANNEL_AUTH_SOCKET: | |
803 | continue; | |
804 | case SSH_CHANNEL_OPENING: | |
805 | case SSH_CHANNEL_OPEN: | |
806 | case SSH_CHANNEL_X11_OPEN: | |
807 | case SSH_CHANNEL_INPUT_DRAINING: | |
808 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
809 | snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n", | |
810 | c->self, c->remote_name, | |
811 | c->type, c->remote_id, c->istate, c->ostate); | |
812 | buffer_append(&buffer, buf, strlen(buf)); | |
813 | continue; | |
814 | default: | |
815 | fatal("channel_still_open: bad channel type %d", c->type); | |
816 | /* NOTREACHED */ | |
817 | } | |
818 | } | |
819 | buffer_append(&buffer, "\0", 1); | |
820 | cp = xstrdup(buffer_ptr(&buffer)); | |
821 | buffer_free(&buffer); | |
822 | return cp; | |
8efc0c15 | 823 | } |
824 | ||
825 | /* Initiate forwarding of connections to local port "port" through the secure | |
826 | channel to host:port from remote side. */ | |
827 | ||
5260325f | 828 | void |
829 | channel_request_local_forwarding(int port, const char *host, | |
830 | int host_port) | |
8efc0c15 | 831 | { |
5260325f | 832 | int ch, sock; |
833 | struct sockaddr_in sin; | |
834 | extern Options options; | |
835 | ||
836 | if (strlen(host) > sizeof(channels[0].path) - 1) | |
837 | packet_disconnect("Forward host name too long."); | |
838 | ||
839 | /* Create a port to listen for the host. */ | |
840 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
841 | if (sock < 0) | |
842 | packet_disconnect("socket: %.100s", strerror(errno)); | |
843 | ||
844 | /* Initialize socket address. */ | |
845 | memset(&sin, 0, sizeof(sin)); | |
846 | sin.sin_family = AF_INET; | |
847 | if (options.gateway_ports == 1) | |
848 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
849 | else | |
850 | sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
851 | sin.sin_port = htons(port); | |
852 | ||
853 | /* Bind the socket to the address. */ | |
854 | if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) | |
855 | packet_disconnect("bind: %.100s", strerror(errno)); | |
856 | ||
857 | /* Start listening for connections on the socket. */ | |
858 | if (listen(sock, 5) < 0) | |
859 | packet_disconnect("listen: %.100s", strerror(errno)); | |
860 | ||
861 | /* Allocate a channel number for the socket. */ | |
862 | ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, | |
863 | xstrdup("port listener")); | |
864 | strcpy(channels[ch].path, host); | |
865 | channels[ch].host_port = host_port; | |
866 | channels[ch].listening_port = port; | |
867 | } | |
8efc0c15 | 868 | |
869 | /* Initiate forwarding of connections to port "port" on remote host through | |
870 | the secure channel to host:port from local side. */ | |
871 | ||
5260325f | 872 | void |
873 | channel_request_remote_forwarding(int port, const char *host, | |
874 | int remote_port) | |
8efc0c15 | 875 | { |
5260325f | 876 | int payload_len; |
877 | /* Record locally that connection to this host/port is permitted. */ | |
878 | if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) | |
879 | fatal("channel_request_remote_forwarding: too many forwards"); | |
880 | ||
881 | permitted_opens[num_permitted_opens].host = xstrdup(host); | |
882 | permitted_opens[num_permitted_opens].port = remote_port; | |
883 | num_permitted_opens++; | |
884 | ||
885 | /* Send the forward request to the remote side. */ | |
886 | packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); | |
887 | packet_put_int(port); | |
888 | packet_put_string(host, strlen(host)); | |
889 | packet_put_int(remote_port); | |
890 | packet_send(); | |
891 | packet_write_wait(); | |
892 | ||
893 | /* Wait for response from the remote side. It will send a | |
894 | disconnect message on failure, and we will never see it here. */ | |
895 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); | |
8efc0c15 | 896 | } |
897 | ||
898 | /* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates | |
899 | listening for the port, and sends back a success reply (or disconnect | |
5260325f | 900 | message if there was an error). This never returns if there was an |
8efc0c15 | 901 | error. */ |
902 | ||
5260325f | 903 | void |
904 | channel_input_port_forward_request(int is_root) | |
8efc0c15 | 905 | { |
5260325f | 906 | int port, host_port; |
907 | char *hostname; | |
908 | ||
909 | /* Get arguments from the packet. */ | |
910 | port = packet_get_int(); | |
911 | hostname = packet_get_string(NULL); | |
912 | host_port = packet_get_int(); | |
913 | ||
914 | /* Port numbers are 16 bit quantities. */ | |
915 | if ((port & 0xffff) != port) | |
916 | packet_disconnect("Requested forwarding of nonexistent port %d.", port); | |
917 | ||
918 | /* Check that an unprivileged user is not trying to forward a | |
919 | privileged port. */ | |
920 | if (port < IPPORT_RESERVED && !is_root) | |
921 | packet_disconnect("Requested forwarding of port %d but user is not root.", | |
922 | port); | |
923 | ||
924 | /* Initiate forwarding. */ | |
925 | channel_request_local_forwarding(port, hostname, host_port); | |
926 | ||
927 | /* Free the argument string. */ | |
928 | xfree(hostname); | |
8efc0c15 | 929 | } |
930 | ||
931 | /* This is called after receiving PORT_OPEN message. This attempts to connect | |
932 | to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or | |
933 | CHANNEL_OPEN_FAILURE. */ | |
934 | ||
5260325f | 935 | void |
936 | channel_input_port_open(int payload_len) | |
8efc0c15 | 937 | { |
5260325f | 938 | int remote_channel, sock, newch, host_port, i; |
939 | struct sockaddr_in sin; | |
940 | char *host, *originator_string; | |
941 | struct hostent *hp; | |
942 | int host_len, originator_len; | |
943 | ||
944 | /* Get remote channel number. */ | |
945 | remote_channel = packet_get_int(); | |
946 | ||
947 | /* Get host name to connect to. */ | |
948 | host = packet_get_string(&host_len); | |
949 | ||
950 | /* Get port to connect to. */ | |
951 | host_port = packet_get_int(); | |
952 | ||
953 | /* Get remote originator name. */ | |
954 | if (have_hostname_in_open) | |
955 | originator_string = packet_get_string(&originator_len); | |
956 | else | |
957 | originator_string = xstrdup("unknown (remote did not supply name)"); | |
958 | ||
959 | packet_integrity_check(payload_len, | |
960 | 4 + 4 + host_len + 4 + 4 + originator_len, | |
961 | SSH_MSG_PORT_OPEN); | |
962 | ||
963 | /* Check if opening that port is permitted. */ | |
964 | if (!all_opens_permitted) { | |
965 | /* Go trough all permitted ports. */ | |
966 | for (i = 0; i < num_permitted_opens; i++) | |
967 | if (permitted_opens[i].port == host_port && | |
968 | strcmp(permitted_opens[i].host, host) == 0) | |
969 | break; | |
970 | ||
971 | /* Check if we found the requested port among those permitted. */ | |
972 | if (i >= num_permitted_opens) { | |
973 | /* The port is not permitted. */ | |
974 | log("Received request to connect to %.100s:%d, but the request was denied.", | |
975 | host, host_port); | |
976 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
977 | packet_put_int(remote_channel); | |
978 | packet_send(); | |
979 | } | |
8efc0c15 | 980 | } |
5260325f | 981 | memset(&sin, 0, sizeof(sin)); |
982 | sin.sin_addr.s_addr = inet_addr(host); | |
983 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { | |
984 | /* It was a valid numeric host address. */ | |
985 | sin.sin_family = AF_INET; | |
986 | } else { | |
987 | /* Look up the host address from the name servers. */ | |
988 | hp = gethostbyname(host); | |
989 | if (!hp) { | |
990 | error("%.100s: unknown host.", host); | |
991 | goto fail; | |
992 | } | |
993 | if (!hp->h_addr_list[0]) { | |
994 | error("%.100s: host has no IP address.", host); | |
995 | goto fail; | |
996 | } | |
997 | sin.sin_family = hp->h_addrtype; | |
998 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
999 | sizeof(sin.sin_addr)); | |
8efc0c15 | 1000 | } |
5260325f | 1001 | sin.sin_port = htons(host_port); |
1002 | ||
1003 | /* Create the socket. */ | |
1004 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1005 | if (sock < 0) { | |
1006 | error("socket: %.100s", strerror(errno)); | |
1007 | goto fail; | |
1008 | } | |
1009 | /* Connect to the host/port. */ | |
1010 | if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1011 | error("connect %.100s:%d: %.100s", host, host_port, | |
1012 | strerror(errno)); | |
1013 | close(sock); | |
1014 | goto fail; | |
8efc0c15 | 1015 | } |
5260325f | 1016 | /* Successful connection. */ |
1017 | ||
1018 | /* Allocate a channel for this connection. */ | |
1019 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); | |
1020 | channels[newch].remote_id = remote_channel; | |
1021 | ||
1022 | /* Send a confirmation to the remote host. */ | |
1023 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1024 | packet_put_int(remote_channel); | |
1025 | packet_put_int(newch); | |
1026 | packet_send(); | |
1027 | ||
1028 | /* Free the argument string. */ | |
1029 | xfree(host); | |
1030 | ||
1031 | return; | |
1032 | ||
1033 | fail: | |
1034 | /* Free the argument string. */ | |
1035 | xfree(host); | |
1036 | ||
1037 | /* Send refusal to the remote host. */ | |
1038 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1039 | packet_put_int(remote_channel); | |
1040 | packet_send(); | |
8efc0c15 | 1041 | } |
1042 | ||
5260325f | 1043 | /* Creates an internet domain socket for listening for X11 connections. |
8efc0c15 | 1044 | Returns a suitable value for the DISPLAY variable, or NULL if an error |
1045 | occurs. */ | |
1046 | ||
5260325f | 1047 | char * |
1048 | x11_create_display_inet(int screen_number) | |
8efc0c15 | 1049 | { |
5260325f | 1050 | extern ServerOptions options; |
1051 | int display_number, port, sock; | |
1052 | struct sockaddr_in sin; | |
1053 | char buf[512]; | |
1054 | char hostname[MAXHOSTNAMELEN]; | |
1055 | ||
1056 | for (display_number = options.x11_display_offset; | |
1057 | display_number < MAX_DISPLAYS; | |
1058 | display_number++) { | |
1059 | port = 6000 + display_number; | |
1060 | memset(&sin, 0, sizeof(sin)); | |
1061 | sin.sin_family = AF_INET; | |
1062 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
1063 | sin.sin_port = htons(port); | |
1064 | ||
1065 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
1066 | if (sock < 0) { | |
1067 | error("socket: %.100s", strerror(errno)); | |
1068 | return NULL; | |
1069 | } | |
1070 | if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1071 | debug("bind port %d: %.100s", port, strerror(errno)); | |
1072 | shutdown(sock, SHUT_RDWR); | |
1073 | close(sock); | |
1074 | continue; | |
1075 | } | |
1076 | break; | |
1077 | } | |
1078 | if (display_number >= MAX_DISPLAYS) { | |
1079 | error("Failed to allocate internet-domain X11 display socket."); | |
1080 | return NULL; | |
8efc0c15 | 1081 | } |
5260325f | 1082 | /* Start listening for connections on the socket. */ |
1083 | if (listen(sock, 5) < 0) { | |
1084 | error("listen: %.100s", strerror(errno)); | |
1085 | shutdown(sock, SHUT_RDWR); | |
1086 | close(sock); | |
1087 | return NULL; | |
8efc0c15 | 1088 | } |
5260325f | 1089 | /* Set up a suitable value for the DISPLAY variable. */ |
1090 | if (gethostname(hostname, sizeof(hostname)) < 0) | |
1091 | fatal("gethostname: %.100s", strerror(errno)); | |
1092 | snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname, | |
1093 | display_number, screen_number); | |
1094 | ||
1095 | /* Allocate a channel for the socket. */ | |
1096 | (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, | |
1097 | xstrdup("X11 inet listener")); | |
1098 | ||
1099 | /* Return a suitable value for the DISPLAY environment variable. */ | |
1100 | return xstrdup(buf); | |
8efc0c15 | 1101 | } |
1102 | ||
1103 | #ifndef X_UNIX_PATH | |
1104 | #define X_UNIX_PATH "/tmp/.X11-unix/X" | |
1105 | #endif | |
1106 | ||
1107 | static | |
1108 | int | |
1109 | connect_local_xsocket(unsigned dnr) | |
1110 | { | |
5260325f | 1111 | static const char *const x_sockets[] = { |
1112 | X_UNIX_PATH "%u", | |
1113 | "/var/X/.X11-unix/X" "%u", | |
1114 | "/usr/spool/sockets/X11/" "%u", | |
1115 | NULL | |
1116 | }; | |
1117 | int sock; | |
1118 | struct sockaddr_un addr; | |
1119 | const char *const * path; | |
1120 | ||
1121 | for (path = x_sockets; *path; ++path) { | |
1122 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1123 | if (sock < 0) | |
1124 | error("socket: %.100s", strerror(errno)); | |
1125 | memset(&addr, 0, sizeof(addr)); | |
1126 | addr.sun_family = AF_UNIX; | |
1127 | snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr); | |
1128 | if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0) | |
1129 | return sock; | |
1130 | close(sock); | |
1131 | } | |
1132 | error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); | |
1133 | return -1; | |
8efc0c15 | 1134 | } |
1135 | ||
1136 | ||
1137 | /* This is called when SSH_SMSG_X11_OPEN is received. The packet contains | |
1138 | the remote channel number. We should do whatever we want, and respond | |
1139 | with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ | |
1140 | ||
5260325f | 1141 | void |
1142 | x11_input_open(int payload_len) | |
8efc0c15 | 1143 | { |
5260325f | 1144 | int remote_channel, display_number, sock, newch; |
1145 | const char *display; | |
1146 | struct sockaddr_in sin; | |
1147 | char buf[1024], *cp, *remote_host; | |
1148 | struct hostent *hp; | |
1149 | int remote_len; | |
1150 | ||
1151 | /* Get remote channel number. */ | |
1152 | remote_channel = packet_get_int(); | |
1153 | ||
1154 | /* Get remote originator name. */ | |
1155 | if (have_hostname_in_open) | |
1156 | remote_host = packet_get_string(&remote_len); | |
1157 | else | |
1158 | remote_host = xstrdup("unknown (remote did not supply name)"); | |
1159 | ||
1160 | debug("Received X11 open request."); | |
1161 | packet_integrity_check(payload_len, 4 + 4 + remote_len, SSH_SMSG_X11_OPEN); | |
1162 | ||
1163 | /* Try to open a socket for the local X server. */ | |
1164 | display = getenv("DISPLAY"); | |
1165 | if (!display) { | |
1166 | error("DISPLAY not set."); | |
1167 | goto fail; | |
1168 | } | |
1169 | /* Now we decode the value of the DISPLAY variable and make a | |
1170 | connection to the real X server. */ | |
1171 | ||
1172 | /* Check if it is a unix domain socket. Unix domain displays are | |
1173 | in one of the following formats: unix:d[.s], :d[.s], ::d[.s] */ | |
1174 | if (strncmp(display, "unix:", 5) == 0 || | |
1175 | display[0] == ':') { | |
1176 | /* Connect to the unix domain socket. */ | |
1177 | if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) { | |
1178 | error("Could not parse display number from DISPLAY: %.100s", | |
1179 | display); | |
1180 | goto fail; | |
1181 | } | |
1182 | /* Create a socket. */ | |
1183 | sock = connect_local_xsocket(display_number); | |
1184 | if (sock < 0) | |
1185 | goto fail; | |
1186 | ||
1187 | /* OK, we now have a connection to the display. */ | |
1188 | goto success; | |
1189 | } | |
1190 | /* Connect to an inet socket. The DISPLAY value is supposedly | |
1191 | hostname:d[.s], where hostname may also be numeric IP address. */ | |
1192 | strncpy(buf, display, sizeof(buf)); | |
1193 | buf[sizeof(buf) - 1] = 0; | |
1194 | cp = strchr(buf, ':'); | |
1195 | if (!cp) { | |
1196 | error("Could not find ':' in DISPLAY: %.100s", display); | |
1197 | goto fail; | |
1198 | } | |
1199 | *cp = 0; | |
1200 | /* buf now contains the host name. But first we parse the display | |
1201 | number. */ | |
1202 | if (sscanf(cp + 1, "%d", &display_number) != 1) { | |
1203 | error("Could not parse display number from DISPLAY: %.100s", | |
1204 | display); | |
1205 | goto fail; | |
1206 | } | |
1207 | /* Try to parse the host name as a numeric IP address. */ | |
1208 | memset(&sin, 0, sizeof(sin)); | |
1209 | sin.sin_addr.s_addr = inet_addr(buf); | |
1210 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { | |
1211 | /* It was a valid numeric host address. */ | |
1212 | sin.sin_family = AF_INET; | |
1213 | } else { | |
1214 | /* Not a numeric IP address. */ | |
1215 | /* Look up the host address from the name servers. */ | |
1216 | hp = gethostbyname(buf); | |
1217 | if (!hp) { | |
1218 | error("%.100s: unknown host.", buf); | |
1219 | goto fail; | |
1220 | } | |
1221 | if (!hp->h_addr_list[0]) { | |
1222 | error("%.100s: host has no IP address.", buf); | |
1223 | goto fail; | |
1224 | } | |
1225 | sin.sin_family = hp->h_addrtype; | |
1226 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
1227 | sizeof(sin.sin_addr)); | |
8efc0c15 | 1228 | } |
5260325f | 1229 | /* Set port number. */ |
1230 | sin.sin_port = htons(6000 + display_number); | |
1231 | ||
1232 | /* Create a socket. */ | |
1233 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1234 | if (sock < 0) { | |
1235 | error("socket: %.100s", strerror(errno)); | |
1236 | goto fail; | |
8efc0c15 | 1237 | } |
5260325f | 1238 | /* Connect it to the display. */ |
1239 | if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
1240 | error("connect %.100s:%d: %.100s", buf, 6000 + display_number, | |
1241 | strerror(errno)); | |
1242 | close(sock); | |
1243 | goto fail; | |
8efc0c15 | 1244 | } |
5260325f | 1245 | success: |
1246 | /* We have successfully obtained a connection to the real X display. */ | |
1247 | ||
1248 | /* Allocate a channel for this connection. */ | |
1249 | if (x11_saved_proto == NULL) | |
1250 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); | |
1251 | else | |
1252 | newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host); | |
1253 | channels[newch].remote_id = remote_channel; | |
1254 | ||
1255 | /* Send a confirmation to the remote host. */ | |
1256 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1257 | packet_put_int(remote_channel); | |
1258 | packet_put_int(newch); | |
1259 | packet_send(); | |
1260 | ||
1261 | return; | |
1262 | ||
1263 | fail: | |
1264 | /* Send refusal to the remote host. */ | |
1265 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1266 | packet_put_int(remote_channel); | |
1267 | packet_send(); | |
8efc0c15 | 1268 | } |
1269 | ||
1270 | /* Requests forwarding of X11 connections, generates fake authentication | |
1271 | data, and enables authentication spoofing. */ | |
1272 | ||
5260325f | 1273 | void |
1274 | x11_request_forwarding_with_spoofing(const char *proto, const char *data) | |
8efc0c15 | 1275 | { |
5260325f | 1276 | unsigned int data_len = (unsigned int) strlen(data) / 2; |
1277 | unsigned int i, value; | |
1278 | char *new_data; | |
1279 | int screen_number; | |
1280 | const char *cp; | |
1281 | u_int32_t rand = 0; | |
1282 | ||
1283 | cp = getenv("DISPLAY"); | |
1284 | if (cp) | |
1285 | cp = strchr(cp, ':'); | |
1286 | if (cp) | |
1287 | cp = strchr(cp, '.'); | |
1288 | if (cp) | |
1289 | screen_number = atoi(cp + 1); | |
1290 | else | |
1291 | screen_number = 0; | |
1292 | ||
1293 | /* Save protocol name. */ | |
1294 | x11_saved_proto = xstrdup(proto); | |
1295 | ||
1296 | /* Extract real authentication data and generate fake data of the | |
1297 | same length. */ | |
1298 | x11_saved_data = xmalloc(data_len); | |
1299 | x11_fake_data = xmalloc(data_len); | |
1300 | for (i = 0; i < data_len; i++) { | |
1301 | if (sscanf(data + 2 * i, "%2x", &value) != 1) | |
1302 | fatal("x11_request_forwarding: bad authentication data: %.100s", data); | |
1303 | if (i % 4 == 0) | |
1304 | rand = arc4random(); | |
1305 | x11_saved_data[i] = value; | |
1306 | x11_fake_data[i] = rand & 0xff; | |
1307 | rand >>= 8; | |
1308 | } | |
1309 | x11_saved_data_len = data_len; | |
1310 | x11_fake_data_len = data_len; | |
1311 | ||
1312 | /* Convert the fake data into hex. */ | |
1313 | new_data = xmalloc(2 * data_len + 1); | |
1314 | for (i = 0; i < data_len; i++) | |
1315 | sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]); | |
1316 | ||
1317 | /* Send the request packet. */ | |
1318 | packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); | |
1319 | packet_put_string(proto, strlen(proto)); | |
1320 | packet_put_string(new_data, strlen(new_data)); | |
1321 | packet_put_int(screen_number); | |
1322 | packet_send(); | |
1323 | packet_write_wait(); | |
1324 | xfree(new_data); | |
8efc0c15 | 1325 | } |
1326 | ||
1327 | /* Sends a message to the server to request authentication fd forwarding. */ | |
1328 | ||
5260325f | 1329 | void |
1330 | auth_request_forwarding() | |
8efc0c15 | 1331 | { |
5260325f | 1332 | packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); |
1333 | packet_send(); | |
1334 | packet_write_wait(); | |
8efc0c15 | 1335 | } |
1336 | ||
1337 | /* Returns the name of the forwarded authentication socket. Returns NULL | |
1338 | if there is no forwarded authentication socket. The returned value | |
1339 | points to a static buffer. */ | |
1340 | ||
5260325f | 1341 | char * |
1342 | auth_get_socket_name() | |
8efc0c15 | 1343 | { |
5260325f | 1344 | return channel_forwarded_auth_socket_name; |
8efc0c15 | 1345 | } |
1346 | ||
1347 | /* removes the agent forwarding socket */ | |
1348 | ||
5260325f | 1349 | void |
1350 | cleanup_socket(void) | |
1351 | { | |
1352 | remove(channel_forwarded_auth_socket_name); | |
1353 | rmdir(channel_forwarded_auth_socket_dir); | |
8efc0c15 | 1354 | } |
1355 | ||
1356 | /* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. | |
1357 | This starts forwarding authentication requests. */ | |
1358 | ||
5260325f | 1359 | void |
1360 | auth_input_request_forwarding(struct passwd * pw) | |
8efc0c15 | 1361 | { |
5260325f | 1362 | int sock, newch; |
1363 | struct sockaddr_un sunaddr; | |
1364 | ||
1365 | if (auth_get_socket_name() != NULL) | |
1366 | fatal("Protocol error: authentication forwarding requested twice."); | |
1367 | ||
1368 | /* Temporarily drop privileged uid for mkdir/bind. */ | |
1369 | temporarily_use_uid(pw->pw_uid); | |
1370 | ||
1371 | /* Allocate a buffer for the socket name, and format the name. */ | |
1372 | channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); | |
1373 | channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); | |
1374 | strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); | |
1375 | ||
1376 | /* Create private directory for socket */ | |
1377 | if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) | |
1378 | packet_disconnect("mkdtemp: %.100s", strerror(errno)); | |
1379 | snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d", | |
1380 | channel_forwarded_auth_socket_dir, (int) getpid()); | |
1381 | ||
1382 | if (atexit(cleanup_socket) < 0) { | |
1383 | int saved = errno; | |
1384 | cleanup_socket(); | |
1385 | packet_disconnect("socket: %.100s", strerror(saved)); | |
1386 | } | |
1387 | /* Create the socket. */ | |
1388 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1389 | if (sock < 0) | |
1390 | packet_disconnect("socket: %.100s", strerror(errno)); | |
1391 | ||
1392 | /* Bind it to the name. */ | |
1393 | memset(&sunaddr, 0, sizeof(sunaddr)); | |
1394 | sunaddr.sun_family = AF_UNIX; | |
1395 | strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name, | |
1396 | sizeof(sunaddr.sun_path)); | |
1397 | ||
1398 | if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) | |
1399 | packet_disconnect("bind: %.100s", strerror(errno)); | |
1400 | ||
1401 | /* Restore the privileged uid. */ | |
1402 | restore_uid(); | |
1403 | ||
1404 | /* Start listening on the socket. */ | |
1405 | if (listen(sock, 5) < 0) | |
1406 | packet_disconnect("listen: %.100s", strerror(errno)); | |
1407 | ||
1408 | /* Allocate a channel for the authentication agent socket. */ | |
1409 | newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, | |
1410 | xstrdup("auth socket")); | |
1411 | strcpy(channels[newch].path, channel_forwarded_auth_socket_name); | |
8efc0c15 | 1412 | } |
1413 | ||
1414 | /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ | |
1415 | ||
5260325f | 1416 | void |
1417 | auth_input_open_request() | |
8efc0c15 | 1418 | { |
5260325f | 1419 | int remch, sock, newch; |
1420 | char *dummyname; | |
1421 | ||
1422 | /* Read the remote channel number from the message. */ | |
1423 | remch = packet_get_int(); | |
1424 | ||
1425 | /* Get a connection to the local authentication agent (this may | |
1426 | again get forwarded). */ | |
1427 | sock = ssh_get_authentication_socket(); | |
1428 | ||
1429 | /* If we could not connect the agent, send an error message back | |
1430 | to the server. This should never happen unless the agent dies, | |
1431 | because authentication forwarding is only enabled if we have an | |
1432 | agent. */ | |
1433 | if (sock < 0) { | |
1434 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1435 | packet_put_int(remch); | |
1436 | packet_send(); | |
1437 | return; | |
1438 | } | |
1439 | debug("Forwarding authentication connection."); | |
1440 | ||
1441 | /* Dummy host name. This will be freed when the channel is freed; | |
1442 | it will still be valid in the packet_put_string below since the | |
1443 | channel cannot yet be freed at that point. */ | |
1444 | dummyname = xstrdup("authentication agent connection"); | |
1445 | ||
1446 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); | |
1447 | channels[newch].remote_id = remch; | |
1448 | ||
1449 | /* Send a confirmation to the remote host. */ | |
1450 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1451 | packet_put_int(remch); | |
1452 | packet_put_int(newch); | |
1453 | packet_send(); | |
8efc0c15 | 1454 | } |