]>
Commit | Line | Data |
---|---|---|
8efc0c15 | 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 "servconf.h" | |
28 | ||
29 | #include "channels.h" | |
30 | #include "nchan.h" | |
31 | #include "compat.h" | |
32 | ||
33 | /* Maximum number of fake X11 displays to try. */ | |
34 | #define MAX_DISPLAYS 1000 | |
35 | ||
36 | /* Max len of agent socket */ | |
37 | #define MAX_SOCKET_NAME 100 | |
38 | ||
39 | /* Pointer to an array containing all allocated channels. The array is | |
40 | dynamically extended as needed. */ | |
41 | static Channel *channels = NULL; | |
42 | ||
43 | /* Size of the channel array. All slots of the array must always be | |
44 | initialized (at least the type field); unused slots are marked with | |
45 | type SSH_CHANNEL_FREE. */ | |
46 | static int channels_alloc = 0; | |
47 | ||
48 | /* Maximum file descriptor value used in any of the channels. This is updated | |
49 | in channel_allocate. */ | |
50 | static int channel_max_fd_value = 0; | |
51 | ||
52 | /* Name and directory of socket for authentication agent forwarding. */ | |
53 | static char *channel_forwarded_auth_socket_name = NULL; | |
54 | static char *channel_forwarded_auth_socket_dir = NULL; | |
55 | ||
56 | /* Saved X11 authentication protocol name. */ | |
57 | char *x11_saved_proto = NULL; | |
58 | ||
59 | /* Saved X11 authentication data. This is the real data. */ | |
60 | char *x11_saved_data = NULL; | |
61 | unsigned int x11_saved_data_len = 0; | |
62 | ||
63 | /* Fake X11 authentication data. This is what the server will be sending | |
64 | us; we should replace any occurrences of this by the real data. */ | |
65 | char *x11_fake_data = NULL; | |
66 | unsigned int x11_fake_data_len; | |
67 | ||
68 | /* Data structure for storing which hosts are permitted for forward requests. | |
69 | The local sides of any remote forwards are stored in this array to prevent | |
70 | a corrupt remote server from accessing arbitrary TCP/IP ports on our | |
71 | local network (which might be behind a firewall). */ | |
72 | typedef struct | |
73 | { | |
74 | char *host; /* Host name. */ | |
75 | int port; /* Port number. */ | |
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 | ||
92 | void channel_set_options(int hostname_in_open) | |
93 | { | |
94 | have_hostname_in_open = hostname_in_open; | |
95 | } | |
96 | ||
97 | /* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually | |
98 | called by the server, because the user could connect to any port anyway, | |
99 | and the server has no way to know but to trust the client anyway. */ | |
100 | ||
101 | void channel_permit_all_opens() | |
102 | { | |
103 | all_opens_permitted = 1; | |
104 | } | |
105 | ||
106 | /* Allocate a new channel object and set its type and socket. | |
107 | This will cause remote_name to be freed. */ | |
108 | ||
109 | int channel_allocate(int type, int sock, char *remote_name) | |
110 | { | |
5068f573 | 111 | int i, found; |
112 | Channel *c; | |
8efc0c15 | 113 | |
114 | /* Update the maximum file descriptor value. */ | |
115 | if (sock > channel_max_fd_value) | |
116 | channel_max_fd_value = sock; | |
117 | ||
118 | /* Do initial allocation if this is the first call. */ | |
119 | if (channels_alloc == 0) | |
120 | { | |
121 | channels_alloc = 10; | |
122 | channels = xmalloc(channels_alloc * sizeof(Channel)); | |
123 | for (i = 0; i < channels_alloc; i++) | |
124 | channels[i].type = SSH_CHANNEL_FREE; | |
125 | ||
126 | /* Kludge: arrange a call to channel_stop_listening if we terminate | |
127 | with fatal(). */ | |
128 | fatal_add_cleanup((void (*)(void *))channel_stop_listening, NULL); | |
129 | } | |
130 | ||
131 | /* Try to find a free slot where to put the new channel. */ | |
5068f573 | 132 | for (found = -1, i = 0; i < channels_alloc; i++) |
8efc0c15 | 133 | if (channels[i].type == SSH_CHANNEL_FREE) |
134 | { | |
5068f573 | 135 | /* Found a free slot. */ |
136 | found = i; | |
137 | break; | |
8efc0c15 | 138 | } |
139 | ||
5068f573 | 140 | if (found == -1) |
141 | { | |
142 | /* There are no free slots. Take last+1 slot and expand the array. */ | |
143 | found = channels_alloc; | |
144 | channels_alloc += 10; | |
145 | debug("channel: expanding %d", channels_alloc); | |
146 | channels = xrealloc(channels, channels_alloc * sizeof(Channel)); | |
147 | for (i = found; i < channels_alloc; i++) | |
148 | channels[i].type = SSH_CHANNEL_FREE; | |
149 | } | |
150 | ||
151 | /* Initialize and return new channel number. */ | |
152 | c=&channels[found]; | |
153 | buffer_init(&c->input); | |
154 | buffer_init(&c->output); | |
155 | chan_init_iostates(c); | |
156 | c->self = found; | |
157 | c->type = type; | |
5068f573 | 158 | c->sock = sock; |
159 | c->remote_id = -1; | |
160 | c->remote_name = remote_name; | |
161 | debug("channel %d: new [%s]", found, remote_name); | |
162 | return found; | |
8efc0c15 | 163 | } |
164 | ||
165 | /* Free the channel and close its socket. */ | |
166 | ||
167 | void channel_free(int channel) | |
168 | { | |
5bae4ab8 | 169 | if (channel < 0 || channel >= channels_alloc || |
170 | channels[channel].type == SSH_CHANNEL_FREE) | |
171 | packet_disconnect("channel free: bad local channel %d", channel); | |
172 | ||
8efc0c15 | 173 | if(compat13) |
174 | shutdown(channels[channel].sock, SHUT_RDWR); | |
175 | close(channels[channel].sock); | |
176 | buffer_free(&channels[channel].input); | |
177 | buffer_free(&channels[channel].output); | |
178 | channels[channel].type = SSH_CHANNEL_FREE; | |
179 | if (channels[channel].remote_name) | |
180 | { | |
181 | xfree(channels[channel].remote_name); | |
182 | channels[channel].remote_name = NULL; | |
183 | } | |
184 | } | |
185 | ||
186 | /* This is called just before select() to add any bits relevant to | |
187 | channels in the select bitmasks. */ | |
188 | ||
189 | void channel_prepare_select(fd_set *readset, fd_set *writeset) | |
190 | { | |
191 | int i; | |
192 | Channel *ch; | |
193 | unsigned char *ucp; | |
194 | unsigned int proto_len, data_len; | |
195 | ||
196 | for (i = 0; i < channels_alloc; i++) | |
197 | { | |
198 | ch = &channels[i]; | |
199 | redo: | |
200 | switch (ch->type) | |
201 | { | |
202 | case SSH_CHANNEL_X11_LISTENER: | |
203 | case SSH_CHANNEL_PORT_LISTENER: | |
204 | case SSH_CHANNEL_AUTH_SOCKET: | |
205 | FD_SET(ch->sock, readset); | |
206 | break; | |
207 | ||
208 | case SSH_CHANNEL_OPEN: | |
209 | if(compat13){ | |
210 | if (buffer_len(&ch->input) < 32768) | |
211 | FD_SET(ch->sock, readset); | |
212 | if (buffer_len(&ch->output) > 0) | |
213 | FD_SET(ch->sock, writeset); | |
214 | break; | |
215 | } | |
216 | /* test whether sockets are 'alive' for read/write */ | |
217 | if (ch->istate == CHAN_INPUT_OPEN) | |
218 | if (buffer_len(&ch->input) < 32768) | |
219 | FD_SET(ch->sock, readset); | |
220 | if (ch->ostate == CHAN_OUTPUT_OPEN || ch->ostate == CHAN_OUTPUT_WAIT_DRAIN){ | |
221 | if (buffer_len(&ch->output) > 0){ | |
222 | FD_SET(ch->sock, writeset); | |
223 | }else if(ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { | |
224 | chan_obuf_empty(ch); | |
225 | } | |
226 | } | |
227 | break; | |
228 | ||
229 | case SSH_CHANNEL_INPUT_DRAINING: | |
230 | if (!compat13) | |
231 | fatal("cannot happen: IN_DRAIN"); | |
232 | if (buffer_len(&ch->input) == 0) | |
233 | { | |
234 | packet_start(SSH_MSG_CHANNEL_CLOSE); | |
235 | packet_put_int(ch->remote_id); | |
236 | packet_send(); | |
237 | ch->type = SSH_CHANNEL_CLOSED; | |
238 | debug("Closing channel %d after input drain.", i); | |
239 | break; | |
240 | } | |
241 | break; | |
242 | ||
243 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
244 | if (!compat13) | |
245 | fatal("cannot happen: OUT_DRAIN"); | |
246 | if (buffer_len(&ch->output) == 0) | |
247 | { | |
248 | /* debug("Freeing channel %d after output drain.", i); */ | |
249 | channel_free(i); | |
250 | break; | |
251 | } | |
252 | FD_SET(ch->sock, writeset); | |
253 | break; | |
254 | ||
255 | case SSH_CHANNEL_X11_OPEN: | |
256 | /* This is a special state for X11 authentication spoofing. An | |
257 | opened X11 connection (when authentication spoofing is being | |
258 | done) remains in this state until the first packet has been | |
259 | completely read. The authentication data in that packet is | |
260 | then substituted by the real data if it matches the fake data, | |
261 | and the channel is put into normal mode. */ | |
262 | ||
263 | /* Check if the fixed size part of the packet is in buffer. */ | |
264 | if (buffer_len(&ch->output) < 12) | |
265 | break; | |
266 | ||
267 | /* Parse the lengths of variable-length fields. */ | |
268 | ucp = (unsigned char *)buffer_ptr(&ch->output); | |
269 | if (ucp[0] == 0x42) | |
270 | { /* Byte order MSB first. */ | |
271 | proto_len = 256 * ucp[6] + ucp[7]; | |
272 | data_len = 256 * ucp[8] + ucp[9]; | |
273 | } | |
274 | else | |
275 | if (ucp[0] == 0x6c) | |
276 | { /* Byte order LSB first. */ | |
277 | proto_len = ucp[6] + 256 * ucp[7]; | |
278 | data_len = ucp[8] + 256 * ucp[9]; | |
279 | } | |
280 | else | |
281 | { | |
282 | debug("Initial X11 packet contains bad byte order byte: 0x%x", | |
283 | ucp[0]); | |
284 | ch->type = SSH_CHANNEL_OPEN; | |
285 | goto reject; | |
286 | } | |
287 | ||
288 | /* Check if the whole packet is in buffer. */ | |
289 | if (buffer_len(&ch->output) < | |
290 | 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) | |
291 | break; | |
292 | ||
293 | /* Check if authentication protocol matches. */ | |
294 | if (proto_len != strlen(x11_saved_proto) || | |
295 | memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) | |
296 | { | |
297 | debug("X11 connection uses different authentication protocol."); | |
298 | ch->type = SSH_CHANNEL_OPEN; | |
299 | goto reject; | |
300 | } | |
301 | ||
302 | /* Check if authentication data matches our fake data. */ | |
303 | if (data_len != x11_fake_data_len || | |
304 | memcmp(ucp + 12 + ((proto_len + 3) & ~3), | |
305 | x11_fake_data, x11_fake_data_len) != 0) | |
306 | { | |
307 | debug("X11 auth data does not match fake data."); | |
308 | ch->type = SSH_CHANNEL_OPEN; | |
309 | goto reject; | |
310 | } | |
311 | ||
5bae4ab8 | 312 | /* Check fake data length */ |
313 | if (x11_fake_data_len != x11_saved_data_len) | |
314 | { | |
315 | error("X11 fake_data_len %d != saved_data_len %d", | |
316 | x11_fake_data_len, x11_saved_data_len); | |
317 | ch->type = SSH_CHANNEL_OPEN; | |
318 | goto reject; | |
319 | } | |
320 | ||
8efc0c15 | 321 | /* Received authentication protocol and data match our fake data. |
322 | Substitute the fake data with real data. */ | |
8efc0c15 | 323 | memcpy(ucp + 12 + ((proto_len + 3) & ~3), |
324 | x11_saved_data, x11_saved_data_len); | |
325 | ||
326 | /* Start normal processing for the channel. */ | |
327 | ch->type = SSH_CHANNEL_OPEN; | |
8efc0c15 | 328 | goto redo; |
329 | ||
330 | reject: | |
331 | /* We have received an X11 connection that has bad authentication | |
332 | information. */ | |
333 | log("X11 connection rejected because of wrong authentication.\r\n"); | |
334 | buffer_clear(&ch->input); | |
335 | buffer_clear(&ch->output); | |
336 | if (compat13) { | |
337 | close(ch->sock); | |
338 | ch->sock = -1; | |
339 | ch->type = SSH_CHANNEL_CLOSED; | |
340 | packet_start(SSH_MSG_CHANNEL_CLOSE); | |
341 | packet_put_int(ch->remote_id); | |
342 | packet_send(); | |
343 | }else{ | |
5068f573 | 344 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
8efc0c15 | 345 | chan_read_failed(ch); |
346 | chan_write_failed(ch); | |
5068f573 | 347 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
8efc0c15 | 348 | } |
349 | break; | |
350 | ||
351 | case SSH_CHANNEL_FREE: | |
352 | default: | |
353 | continue; | |
354 | } | |
355 | } | |
356 | } | |
357 | ||
358 | /* After select, perform any appropriate operations for channels which | |
359 | have events pending. */ | |
360 | ||
361 | void channel_after_select(fd_set *readset, fd_set *writeset) | |
362 | { | |
363 | struct sockaddr addr; | |
364 | int addrlen, newsock, i, newch, len; | |
365 | Channel *ch; | |
366 | char buf[16384], *remote_hostname; | |
367 | ||
368 | /* Loop over all channels... */ | |
369 | for (i = 0; i < channels_alloc; i++) | |
370 | { | |
371 | ch = &channels[i]; | |
372 | switch (ch->type) | |
373 | { | |
374 | case SSH_CHANNEL_X11_LISTENER: | |
375 | /* This is our fake X11 server socket. */ | |
376 | if (FD_ISSET(ch->sock, readset)) | |
377 | { | |
378 | debug("X11 connection requested."); | |
379 | addrlen = sizeof(addr); | |
380 | newsock = accept(ch->sock, &addr, &addrlen); | |
381 | if (newsock < 0) | |
382 | { | |
383 | error("accept: %.100s", strerror(errno)); | |
384 | break; | |
385 | } | |
386 | remote_hostname = get_remote_hostname(newsock); | |
387 | snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", | |
388 | remote_hostname, get_peer_port(newsock)); | |
389 | xfree(remote_hostname); | |
390 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
391 | xstrdup(buf)); | |
392 | packet_start(SSH_SMSG_X11_OPEN); | |
393 | packet_put_int(newch); | |
394 | if (have_hostname_in_open) | |
395 | packet_put_string(buf, strlen(buf)); | |
396 | packet_send(); | |
397 | } | |
398 | break; | |
399 | ||
400 | case SSH_CHANNEL_PORT_LISTENER: | |
401 | /* This socket is listening for connections to a forwarded TCP/IP | |
402 | port. */ | |
403 | if (FD_ISSET(ch->sock, readset)) | |
404 | { | |
405 | debug("Connection to port %d forwarding to %.100s:%d requested.", | |
406 | ch->listening_port, ch->path, ch->host_port); | |
407 | addrlen = sizeof(addr); | |
408 | newsock = accept(ch->sock, &addr, &addrlen); | |
409 | if (newsock < 0) | |
410 | { | |
411 | error("accept: %.100s", strerror(errno)); | |
412 | break; | |
413 | } | |
414 | remote_hostname = get_remote_hostname(newsock); | |
5068f573 | 415 | snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d", |
416 | ch->listening_port, ch->path, ch->host_port, | |
417 | remote_hostname, get_peer_port(newsock)); | |
8efc0c15 | 418 | xfree(remote_hostname); |
419 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
420 | xstrdup(buf)); | |
421 | packet_start(SSH_MSG_PORT_OPEN); | |
422 | packet_put_int(newch); | |
423 | packet_put_string(ch->path, strlen(ch->path)); | |
424 | packet_put_int(ch->host_port); | |
425 | if (have_hostname_in_open) | |
426 | packet_put_string(buf, strlen(buf)); | |
427 | packet_send(); | |
428 | } | |
429 | break; | |
430 | ||
431 | case SSH_CHANNEL_AUTH_SOCKET: | |
432 | /* This is the authentication agent socket listening for connections | |
433 | from clients. */ | |
434 | if (FD_ISSET(ch->sock, readset)) | |
435 | { | |
436 | int nchan; | |
437 | len = sizeof(addr); | |
438 | newsock = accept(ch->sock, &addr, &len); | |
439 | if (newsock < 0) | |
440 | { | |
441 | error("accept from auth socket: %.100s", strerror(errno)); | |
442 | break; | |
443 | } | |
444 | ||
445 | nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, | |
446 | xstrdup("accepted auth socket")); | |
447 | packet_start(SSH_SMSG_AGENT_OPEN); | |
448 | packet_put_int(nchan); | |
449 | packet_send(); | |
450 | } | |
451 | break; | |
452 | ||
453 | case SSH_CHANNEL_OPEN: | |
454 | /* This is an open two-way communication channel. It is not of | |
455 | interest to us at this point what kind of data is being | |
456 | transmitted. */ | |
457 | ||
458 | /* Read available incoming data and append it to buffer; | |
459 | shutdown socket, if read or write failes */ | |
460 | if (FD_ISSET(ch->sock, readset)) | |
461 | { | |
462 | len = read(ch->sock, buf, sizeof(buf)); | |
463 | if (len <= 0) | |
464 | { | |
465 | if (compat13) { | |
466 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
467 | ch->type = SSH_CHANNEL_INPUT_DRAINING; | |
468 | debug("Channel %d status set to input draining.", i); | |
469 | }else{ | |
470 | chan_read_failed(ch); | |
471 | } | |
472 | break; | |
473 | } | |
474 | buffer_append(&ch->input, buf, len); | |
475 | } | |
476 | /* Send buffered output data to the socket. */ | |
477 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) | |
478 | { | |
479 | len = write(ch->sock, buffer_ptr(&ch->output), | |
480 | buffer_len(&ch->output)); | |
481 | if (len <= 0) | |
482 | { | |
483 | if (compat13) { | |
484 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
485 | debug("Channel %d status set to input draining.", i); | |
486 | ch->type = SSH_CHANNEL_INPUT_DRAINING; | |
487 | }else{ | |
488 | chan_write_failed(ch); | |
489 | } | |
490 | break; | |
491 | } | |
492 | buffer_consume(&ch->output, len); | |
493 | } | |
494 | break; | |
495 | ||
496 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
497 | if (!compat13) | |
498 | fatal("cannot happen: OUT_DRAIN"); | |
499 | /* Send buffered output data to the socket. */ | |
500 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) | |
501 | { | |
502 | len = write(ch->sock, buffer_ptr(&ch->output), | |
503 | buffer_len(&ch->output)); | |
504 | if (len <= 0) | |
505 | buffer_consume(&ch->output, buffer_len(&ch->output)); | |
506 | else | |
507 | buffer_consume(&ch->output, len); | |
508 | } | |
509 | break; | |
510 | ||
511 | case SSH_CHANNEL_X11_OPEN: | |
512 | case SSH_CHANNEL_FREE: | |
513 | default: | |
514 | continue; | |
515 | } | |
516 | } | |
517 | } | |
518 | ||
519 | /* If there is data to send to the connection, send some of it now. */ | |
520 | ||
521 | void channel_output_poll() | |
522 | { | |
523 | int len, i; | |
524 | Channel *ch; | |
525 | ||
526 | for (i = 0; i < channels_alloc; i++) | |
527 | { | |
528 | ch = &channels[i]; | |
529 | /* We are only interested in channels that can have buffered incoming | |
530 | data. */ | |
531 | if (ch->type != SSH_CHANNEL_OPEN && | |
532 | ch->type != SSH_CHANNEL_INPUT_DRAINING) | |
533 | continue; | |
534 | ||
535 | /* Get the amount of buffered data for this channel. */ | |
536 | len = buffer_len(&ch->input); | |
537 | if (len > 0) | |
538 | { | |
539 | /* Send some data for the other side over the secure connection. */ | |
540 | if (packet_is_interactive()) | |
541 | { | |
542 | if (len > 1024) | |
543 | len = 512; | |
544 | } | |
545 | else | |
546 | { | |
547 | if (len > 16384) | |
548 | len = 16384; /* Keep the packets at reasonable size. */ | |
549 | } | |
550 | packet_start(SSH_MSG_CHANNEL_DATA); | |
551 | packet_put_int(ch->remote_id); | |
552 | packet_put_string(buffer_ptr(&ch->input), len); | |
553 | packet_send(); | |
554 | buffer_consume(&ch->input, len); | |
555 | } | |
556 | else if(ch->istate == CHAN_INPUT_WAIT_DRAIN) | |
557 | { | |
558 | if (compat13) | |
559 | fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); | |
560 | /* input-buffer is empty and read-socket shutdown: | |
561 | tell peer, that we will not send more data: send IEOF */ | |
562 | chan_ibuf_empty(ch); | |
563 | } | |
564 | } | |
565 | } | |
566 | ||
567 | /* This is called when a packet of type CHANNEL_DATA has just been received. | |
568 | The message type has already been consumed, but channel number and data | |
569 | is still there. */ | |
570 | ||
571 | void channel_input_data(int payload_len) | |
572 | { | |
573 | int channel; | |
574 | char *data; | |
575 | unsigned int data_len; | |
576 | ||
577 | /* Get the channel number and verify it. */ | |
578 | channel = packet_get_int(); | |
579 | if (channel < 0 || channel >= channels_alloc || | |
580 | channels[channel].type == SSH_CHANNEL_FREE) | |
581 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
582 | ||
583 | /* Ignore any data for non-open channels (might happen on close) */ | |
584 | if (channels[channel].type != SSH_CHANNEL_OPEN && | |
585 | channels[channel].type != SSH_CHANNEL_X11_OPEN) | |
586 | return; | |
587 | ||
588 | /* Get the data. */ | |
589 | data = packet_get_string(&data_len); | |
590 | packet_integrity_check(payload_len, 4 + 4+data_len, SSH_MSG_CHANNEL_DATA); | |
591 | buffer_append(&channels[channel].output, data, data_len); | |
592 | xfree(data); | |
593 | } | |
594 | ||
595 | /* Returns true if no channel has too much buffered data, and false if | |
596 | one or more channel is overfull. */ | |
597 | ||
598 | int channel_not_very_much_buffered_data() | |
599 | { | |
600 | unsigned int i; | |
601 | Channel *ch; | |
602 | ||
603 | for (i = 0; i < channels_alloc; i++) | |
604 | { | |
605 | ch = &channels[i]; | |
606 | switch (ch->type) | |
607 | { | |
608 | case SSH_CHANNEL_X11_LISTENER: | |
609 | case SSH_CHANNEL_PORT_LISTENER: | |
610 | case SSH_CHANNEL_AUTH_SOCKET: | |
611 | continue; | |
612 | case SSH_CHANNEL_OPEN: | |
613 | if (buffer_len(&ch->input) > 32768) | |
614 | return 0; | |
615 | if (buffer_len(&ch->output) > 32768) | |
616 | return 0; | |
617 | continue; | |
618 | case SSH_CHANNEL_INPUT_DRAINING: | |
619 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
620 | case SSH_CHANNEL_X11_OPEN: | |
621 | case SSH_CHANNEL_FREE: | |
622 | default: | |
623 | continue; | |
624 | } | |
625 | } | |
626 | return 1; | |
627 | } | |
628 | ||
629 | /* This is called after receiving CHANNEL_CLOSE/IEOF. */ | |
630 | ||
631 | void channel_input_close() | |
632 | { | |
633 | int channel; | |
634 | ||
635 | /* Get the channel number and verify it. */ | |
636 | channel = packet_get_int(); | |
637 | if (channel < 0 || channel >= channels_alloc || | |
638 | channels[channel].type == SSH_CHANNEL_FREE) | |
639 | packet_disconnect("Received data for nonexistent channel %d.", channel); | |
640 | ||
641 | if(!compat13){ | |
642 | /* proto version 1.5 overloads CLOSE with IEOF */ | |
643 | chan_rcvd_ieof(&channels[channel]); | |
644 | return; | |
645 | } | |
646 | ||
647 | /* Send a confirmation that we have closed the channel and no more data is | |
648 | coming for it. */ | |
649 | packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); | |
650 | packet_put_int(channels[channel].remote_id); | |
651 | packet_send(); | |
652 | ||
653 | /* If the channel is in closed state, we have sent a close request, and | |
654 | the other side will eventually respond with a confirmation. Thus, | |
655 | we cannot free the channel here, because then there would be no-one to | |
656 | receive the confirmation. The channel gets freed when the confirmation | |
657 | arrives. */ | |
658 | if (channels[channel].type != SSH_CHANNEL_CLOSED) | |
659 | { | |
660 | /* Not a closed channel - mark it as draining, which will cause it to | |
661 | be freed later. */ | |
662 | buffer_consume(&channels[channel].input, | |
663 | buffer_len(&channels[channel].input)); | |
664 | channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; | |
665 | /* debug("Setting status to output draining; output len = %d", | |
666 | buffer_len(&channels[channel].output)); */ | |
667 | } | |
668 | } | |
669 | ||
670 | /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ | |
671 | ||
672 | void channel_input_close_confirmation() | |
673 | { | |
674 | int channel; | |
675 | ||
676 | /* Get the channel number and verify it. */ | |
677 | channel = packet_get_int(); | |
678 | if (channel < 0 || channel >= channels_alloc) | |
679 | packet_disconnect("Received close confirmation for out-of-range channel %d.", | |
680 | channel); | |
681 | ||
682 | if(!compat13){ | |
683 | /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ | |
684 | chan_rcvd_oclose(&channels[channel]); | |
685 | return; | |
686 | } | |
687 | ||
688 | if (channels[channel].type != SSH_CHANNEL_CLOSED) | |
689 | packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", | |
690 | channel, channels[channel].type); | |
691 | ||
692 | /* Free the channel. */ | |
693 | channel_free(channel); | |
694 | } | |
695 | ||
696 | /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ | |
697 | ||
698 | void channel_input_open_confirmation() | |
699 | { | |
700 | int channel, remote_channel; | |
701 | ||
702 | /* Get the channel number and verify it. */ | |
703 | channel = packet_get_int(); | |
704 | if (channel < 0 || channel >= channels_alloc || | |
705 | channels[channel].type != SSH_CHANNEL_OPENING) | |
706 | packet_disconnect("Received open confirmation for non-opening channel %d.", | |
707 | channel); | |
708 | ||
709 | /* Get remote side's id for this channel. */ | |
710 | remote_channel = packet_get_int(); | |
711 | ||
712 | /* Record the remote channel number and mark that the channel is now open. */ | |
713 | channels[channel].remote_id = remote_channel; | |
714 | channels[channel].type = SSH_CHANNEL_OPEN; | |
715 | } | |
716 | ||
717 | /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ | |
718 | ||
719 | void channel_input_open_failure() | |
720 | { | |
721 | int channel; | |
722 | ||
723 | /* Get the channel number and verify it. */ | |
724 | channel = packet_get_int(); | |
725 | if (channel < 0 || channel >= channels_alloc || | |
726 | channels[channel].type != SSH_CHANNEL_OPENING) | |
727 | packet_disconnect("Received open failure for non-opening channel %d.", | |
728 | channel); | |
729 | ||
730 | /* Free the channel. This will also close the socket. */ | |
731 | channel_free(channel); | |
732 | } | |
733 | ||
734 | /* Stops listening for channels, and removes any unix domain sockets that | |
735 | we might have. */ | |
736 | ||
737 | void channel_stop_listening() | |
738 | { | |
739 | int i; | |
740 | for (i = 0; i < channels_alloc; i++) | |
741 | { | |
742 | switch (channels[i].type) | |
743 | { | |
744 | case SSH_CHANNEL_AUTH_SOCKET: | |
745 | close(channels[i].sock); | |
746 | remove(channels[i].path); | |
747 | channel_free(i); | |
748 | break; | |
749 | case SSH_CHANNEL_PORT_LISTENER: | |
750 | case SSH_CHANNEL_X11_LISTENER: | |
751 | close(channels[i].sock); | |
752 | channel_free(i); | |
753 | break; | |
754 | default: | |
755 | break; | |
756 | } | |
757 | } | |
758 | } | |
759 | ||
760 | /* Closes the sockets of all channels. This is used to close extra file | |
761 | descriptors after a fork. */ | |
762 | ||
763 | void channel_close_all() | |
764 | { | |
765 | int i; | |
766 | for (i = 0; i < channels_alloc; i++) | |
767 | { | |
768 | if (channels[i].type != SSH_CHANNEL_FREE) | |
769 | close(channels[i].sock); | |
770 | } | |
771 | } | |
772 | ||
773 | /* Returns the maximum file descriptor number used by the channels. */ | |
774 | ||
775 | int channel_max_fd() | |
776 | { | |
777 | return channel_max_fd_value; | |
778 | } | |
779 | ||
780 | /* Returns true if any channel is still open. */ | |
781 | ||
782 | int channel_still_open() | |
783 | { | |
784 | unsigned int i; | |
785 | for (i = 0; i < channels_alloc; i++) | |
786 | switch (channels[i].type) | |
787 | { | |
788 | case SSH_CHANNEL_FREE: | |
789 | case SSH_CHANNEL_X11_LISTENER: | |
790 | case SSH_CHANNEL_PORT_LISTENER: | |
791 | case SSH_CHANNEL_CLOSED: | |
792 | case SSH_CHANNEL_AUTH_SOCKET: | |
793 | continue; | |
794 | case SSH_CHANNEL_OPENING: | |
795 | case SSH_CHANNEL_OPEN: | |
796 | case SSH_CHANNEL_X11_OPEN: | |
797 | return 1; | |
798 | case SSH_CHANNEL_INPUT_DRAINING: | |
799 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
800 | if (!compat13) | |
801 | fatal("cannot happen: OUT_DRAIN"); | |
802 | return 1; | |
803 | default: | |
804 | fatal("channel_still_open: bad channel type %d", channels[i].type); | |
805 | /*NOTREACHED*/ | |
806 | } | |
807 | return 0; | |
808 | } | |
809 | ||
810 | /* Returns a message describing the currently open forwarded | |
811 | connections, suitable for sending to the client. The message | |
812 | contains crlf pairs for newlines. */ | |
813 | ||
814 | char *channel_open_message() | |
815 | { | |
816 | Buffer buffer; | |
817 | int i; | |
818 | char buf[512], *cp; | |
819 | ||
820 | buffer_init(&buffer); | |
821 | snprintf(buf, sizeof buf, "The following connections are open:\r\n"); | |
822 | buffer_append(&buffer, buf, strlen(buf)); | |
823 | for (i = 0; i < channels_alloc; i++){ | |
824 | Channel *c=&channels[i]; | |
825 | switch (c->type) | |
826 | { | |
827 | case SSH_CHANNEL_FREE: | |
828 | case SSH_CHANNEL_X11_LISTENER: | |
829 | case SSH_CHANNEL_PORT_LISTENER: | |
830 | case SSH_CHANNEL_CLOSED: | |
831 | case SSH_CHANNEL_AUTH_SOCKET: | |
832 | continue; | |
833 | case SSH_CHANNEL_OPENING: | |
834 | case SSH_CHANNEL_OPEN: | |
835 | case SSH_CHANNEL_X11_OPEN: | |
836 | case SSH_CHANNEL_INPUT_DRAINING: | |
837 | case SSH_CHANNEL_OUTPUT_DRAINING: | |
5068f573 | 838 | snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n", |
839 | c->self,c->remote_name, | |
840 | c->type,c->remote_id, c->istate,c->ostate); | |
8efc0c15 | 841 | buffer_append(&buffer, buf, strlen(buf)); |
842 | continue; | |
843 | default: | |
844 | fatal("channel_still_open: bad channel type %d", c->type); | |
845 | /*NOTREACHED*/ | |
846 | } | |
847 | } | |
848 | buffer_append(&buffer, "\0", 1); | |
849 | cp = xstrdup(buffer_ptr(&buffer)); | |
850 | buffer_free(&buffer); | |
851 | return cp; | |
852 | } | |
853 | ||
854 | /* Initiate forwarding of connections to local port "port" through the secure | |
855 | channel to host:port from remote side. */ | |
856 | ||
857 | void channel_request_local_forwarding(int port, const char *host, | |
858 | int host_port) | |
859 | { | |
860 | int ch, sock; | |
861 | struct sockaddr_in sin; | |
862 | extern Options options; | |
863 | ||
864 | if (strlen(host) > sizeof(channels[0].path) - 1) | |
865 | packet_disconnect("Forward host name too long."); | |
866 | ||
867 | /* Create a port to listen for the host. */ | |
868 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
869 | if (sock < 0) | |
870 | packet_disconnect("socket: %.100s", strerror(errno)); | |
871 | ||
872 | /* Initialize socket address. */ | |
873 | memset(&sin, 0, sizeof(sin)); | |
874 | sin.sin_family = AF_INET; | |
875 | if (options.gateway_ports == 1) | |
876 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
877 | else | |
878 | sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
879 | sin.sin_port = htons(port); | |
880 | ||
881 | /* Bind the socket to the address. */ | |
882 | if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
883 | packet_disconnect("bind: %.100s", strerror(errno)); | |
884 | ||
885 | /* Start listening for connections on the socket. */ | |
886 | if (listen(sock, 5) < 0) | |
887 | packet_disconnect("listen: %.100s", strerror(errno)); | |
888 | ||
889 | /* Allocate a channel number for the socket. */ | |
890 | ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, | |
891 | xstrdup("port listener")); | |
892 | strcpy(channels[ch].path, host); /* note: host name stored here */ | |
893 | channels[ch].host_port = host_port; /* port on host to connect to */ | |
894 | channels[ch].listening_port = port; /* port being listened */ | |
895 | } | |
896 | ||
897 | /* Initiate forwarding of connections to port "port" on remote host through | |
898 | the secure channel to host:port from local side. */ | |
899 | ||
900 | void channel_request_remote_forwarding(int port, const char *host, | |
901 | int remote_port) | |
902 | { | |
903 | int payload_len; | |
904 | /* Record locally that connection to this host/port is permitted. */ | |
905 | if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) | |
906 | fatal("channel_request_remote_forwarding: too many forwards"); | |
907 | permitted_opens[num_permitted_opens].host = xstrdup(host); | |
908 | permitted_opens[num_permitted_opens].port = remote_port; | |
909 | num_permitted_opens++; | |
910 | ||
911 | /* Send the forward request to the remote side. */ | |
912 | packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); | |
913 | packet_put_int(port); | |
914 | packet_put_string(host, strlen(host)); | |
915 | packet_put_int(remote_port); | |
916 | packet_send(); | |
917 | packet_write_wait(); | |
918 | ||
919 | /* Wait for response from the remote side. It will send a disconnect | |
920 | message on failure, and we will never see it here. */ | |
921 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); | |
922 | } | |
923 | ||
924 | /* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates | |
925 | listening for the port, and sends back a success reply (or disconnect | |
926 | message if there was an error). This never returns if there was an | |
927 | error. */ | |
928 | ||
929 | void channel_input_port_forward_request(int is_root) | |
930 | { | |
931 | int port, host_port; | |
932 | char *hostname; | |
933 | ||
934 | /* Get arguments from the packet. */ | |
935 | port = packet_get_int(); | |
936 | hostname = packet_get_string(NULL); | |
937 | host_port = packet_get_int(); | |
938 | ||
939 | /* Port numbers are 16 bit quantities. */ | |
940 | if ((port & 0xffff) != port) | |
941 | packet_disconnect("Requested forwarding of nonexistent port %d.", port); | |
942 | ||
943 | /* Check that an unprivileged user is not trying to forward a privileged | |
944 | port. */ | |
945 | if (port < IPPORT_RESERVED && !is_root) | |
946 | packet_disconnect("Requested forwarding of port %d but user is not root.", | |
947 | port); | |
948 | ||
949 | /* Initiate forwarding. */ | |
950 | channel_request_local_forwarding(port, hostname, host_port); | |
951 | ||
952 | /* Free the argument string. */ | |
953 | xfree(hostname); | |
954 | } | |
955 | ||
956 | /* This is called after receiving PORT_OPEN message. This attempts to connect | |
957 | to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or | |
958 | CHANNEL_OPEN_FAILURE. */ | |
959 | ||
960 | void channel_input_port_open(int payload_len) | |
961 | { | |
962 | int remote_channel, sock, newch, host_port, i; | |
963 | struct sockaddr_in sin; | |
964 | char *host, *originator_string; | |
965 | struct hostent *hp; | |
966 | int host_len, originator_len; | |
967 | ||
968 | /* Get remote channel number. */ | |
969 | remote_channel = packet_get_int(); | |
970 | ||
971 | /* Get host name to connect to. */ | |
972 | host = packet_get_string(&host_len); | |
973 | ||
974 | /* Get port to connect to. */ | |
975 | host_port = packet_get_int(); | |
976 | ||
977 | /* Get remote originator name. */ | |
978 | if (have_hostname_in_open) | |
979 | originator_string = packet_get_string(&originator_len); | |
980 | else | |
981 | originator_string = xstrdup("unknown (remote did not supply name)"); | |
982 | ||
983 | packet_integrity_check(payload_len, | |
984 | 4 + 4 + host_len + 4 + 4 + originator_len, | |
985 | SSH_MSG_PORT_OPEN); | |
986 | ||
987 | /* Check if opening that port is permitted. */ | |
988 | if (!all_opens_permitted) | |
989 | { | |
990 | /* Go trough all permitted ports. */ | |
991 | for (i = 0; i < num_permitted_opens; i++) | |
992 | if (permitted_opens[i].port == host_port && | |
993 | strcmp(permitted_opens[i].host, host) == 0) | |
994 | break; | |
995 | ||
996 | /* Check if we found the requested port among those permitted. */ | |
997 | if (i >= num_permitted_opens) | |
998 | { | |
999 | /* The port is not permitted. */ | |
1000 | log("Received request to connect to %.100s:%d, but the request was denied.", | |
1001 | host, host_port); | |
1002 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1003 | packet_put_int(remote_channel); | |
1004 | packet_send(); | |
1005 | } | |
1006 | } | |
1007 | ||
1008 | memset(&sin, 0, sizeof(sin)); | |
1009 | sin.sin_addr.s_addr = inet_addr(host); | |
1010 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) | |
1011 | { | |
1012 | /* It was a valid numeric host address. */ | |
1013 | sin.sin_family = AF_INET; | |
1014 | } | |
1015 | else | |
1016 | { | |
1017 | /* Look up the host address from the name servers. */ | |
1018 | hp = gethostbyname(host); | |
1019 | if (!hp) | |
1020 | { | |
1021 | error("%.100s: unknown host.", host); | |
1022 | goto fail; | |
1023 | } | |
1024 | if (!hp->h_addr_list[0]) | |
1025 | { | |
1026 | error("%.100s: host has no IP address.", host); | |
1027 | goto fail; | |
1028 | } | |
1029 | sin.sin_family = hp->h_addrtype; | |
1030 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
1031 | sizeof(sin.sin_addr)); | |
1032 | } | |
1033 | sin.sin_port = htons(host_port); | |
1034 | ||
1035 | /* Create the socket. */ | |
1036 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1037 | if (sock < 0) | |
1038 | { | |
1039 | error("socket: %.100s", strerror(errno)); | |
1040 | goto fail; | |
1041 | } | |
1042 | ||
1043 | /* Connect to the host/port. */ | |
1044 | if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
1045 | { | |
1046 | error("connect %.100s:%d: %.100s", host, host_port, | |
1047 | strerror(errno)); | |
1048 | close(sock); | |
1049 | goto fail; | |
1050 | } | |
1051 | ||
1052 | /* Successful connection. */ | |
1053 | ||
1054 | /* Allocate a channel for this connection. */ | |
1055 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); | |
1056 | channels[newch].remote_id = remote_channel; | |
1057 | ||
1058 | /* Send a confirmation to the remote host. */ | |
1059 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1060 | packet_put_int(remote_channel); | |
1061 | packet_put_int(newch); | |
1062 | packet_send(); | |
1063 | ||
1064 | /* Free the argument string. */ | |
1065 | xfree(host); | |
1066 | ||
1067 | return; | |
1068 | ||
1069 | fail: | |
1070 | /* Free the argument string. */ | |
1071 | xfree(host); | |
1072 | ||
1073 | /* Send refusal to the remote host. */ | |
1074 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1075 | packet_put_int(remote_channel); | |
1076 | packet_send(); | |
1077 | } | |
1078 | ||
1079 | /* Creates an internet domain socket for listening for X11 connections. | |
1080 | Returns a suitable value for the DISPLAY variable, or NULL if an error | |
1081 | occurs. */ | |
1082 | ||
1083 | char *x11_create_display_inet(int screen_number) | |
1084 | { | |
1085 | extern ServerOptions options; | |
1086 | int display_number, port, sock; | |
1087 | struct sockaddr_in sin; | |
1088 | char buf[512]; | |
1089 | char hostname[MAXHOSTNAMELEN]; | |
1090 | ||
1091 | for (display_number = options.x11_display_offset; display_number < MAX_DISPLAYS; display_number++) | |
1092 | { | |
1093 | port = 6000 + display_number; | |
1094 | memset(&sin, 0, sizeof(sin)); | |
1095 | sin.sin_family = AF_INET; | |
1096 | sin.sin_addr.s_addr = htonl(INADDR_ANY); | |
1097 | sin.sin_port = htons(port); | |
1098 | ||
1099 | sock = socket(AF_INET, SOCK_STREAM, 0); | |
1100 | if (sock < 0) | |
1101 | { | |
1102 | error("socket: %.100s", strerror(errno)); | |
1103 | return NULL; | |
1104 | } | |
1105 | ||
1106 | if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
1107 | { | |
1108 | debug("bind port %d: %.100s", port, strerror(errno)); | |
1109 | shutdown(sock, SHUT_RDWR); | |
1110 | close(sock); | |
1111 | continue; | |
1112 | } | |
1113 | break; | |
1114 | } | |
1115 | if (display_number >= MAX_DISPLAYS) | |
1116 | { | |
1117 | error("Failed to allocate internet-domain X11 display socket."); | |
1118 | return NULL; | |
1119 | } | |
1120 | ||
1121 | /* Start listening for connections on the socket. */ | |
1122 | if (listen(sock, 5) < 0) | |
1123 | { | |
1124 | error("listen: %.100s", strerror(errno)); | |
1125 | shutdown(sock, SHUT_RDWR); | |
1126 | close(sock); | |
1127 | return NULL; | |
1128 | } | |
1129 | ||
1130 | /* Set up a suitable value for the DISPLAY variable. */ | |
1131 | if (gethostname(hostname, sizeof(hostname)) < 0) | |
1132 | fatal("gethostname: %.100s", strerror(errno)); | |
1133 | snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname, | |
1134 | display_number, screen_number); | |
1135 | ||
1136 | /* Allocate a channel for the socket. */ | |
1137 | (void)channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, | |
1138 | xstrdup("X11 inet listener")); | |
1139 | ||
1140 | /* Return a suitable value for the DISPLAY environment variable. */ | |
1141 | return xstrdup(buf); | |
1142 | } | |
1143 | ||
1144 | #ifndef X_UNIX_PATH | |
1145 | #define X_UNIX_PATH "/tmp/.X11-unix/X" | |
1146 | #endif | |
1147 | ||
1148 | static | |
1149 | int | |
1150 | connect_local_xsocket(unsigned dnr) | |
1151 | { | |
1152 | static const char *const x_sockets[] = { | |
1153 | X_UNIX_PATH "%u", | |
1154 | "/var/X/.X11-unix/X" "%u", | |
1155 | "/usr/spool/sockets/X11/" "%u", | |
1156 | NULL | |
1157 | }; | |
1158 | int sock; | |
1159 | struct sockaddr_un addr; | |
1160 | const char *const *path; | |
1161 | ||
1162 | for (path = x_sockets; *path; ++path) | |
1163 | { | |
1164 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1165 | if (sock < 0) | |
1166 | error("socket: %.100s", strerror(errno)); | |
1167 | memset(&addr, 0, sizeof(addr)); | |
1168 | addr.sun_family = AF_UNIX; | |
1169 | snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr); | |
1170 | if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) | |
1171 | return sock; | |
1172 | close(sock); | |
1173 | } | |
1174 | error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); | |
1175 | return -1; | |
1176 | } | |
1177 | ||
1178 | ||
1179 | /* This is called when SSH_SMSG_X11_OPEN is received. The packet contains | |
1180 | the remote channel number. We should do whatever we want, and respond | |
1181 | with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ | |
1182 | ||
1183 | void x11_input_open(int payload_len) | |
1184 | { | |
1185 | int remote_channel, display_number, sock, newch; | |
1186 | const char *display; | |
1187 | struct sockaddr_in sin; | |
1188 | char buf[1024], *cp, *remote_host; | |
1189 | struct hostent *hp; | |
1190 | int remote_len; | |
1191 | ||
1192 | /* Get remote channel number. */ | |
1193 | remote_channel = packet_get_int(); | |
1194 | ||
1195 | /* Get remote originator name. */ | |
1196 | if (have_hostname_in_open) | |
1197 | remote_host = packet_get_string(&remote_len); | |
1198 | else | |
1199 | remote_host = xstrdup("unknown (remote did not supply name)"); | |
1200 | ||
1201 | debug("Received X11 open request."); | |
1202 | packet_integrity_check(payload_len, 4 + 4+remote_len, SSH_SMSG_X11_OPEN); | |
1203 | ||
1204 | /* Try to open a socket for the local X server. */ | |
1205 | display = getenv("DISPLAY"); | |
1206 | if (!display) | |
1207 | { | |
1208 | error("DISPLAY not set."); | |
1209 | goto fail; | |
1210 | } | |
1211 | ||
1212 | /* Now we decode the value of the DISPLAY variable and make a connection | |
1213 | to the real X server. */ | |
1214 | ||
1215 | /* Check if it is a unix domain socket. Unix domain displays are in one | |
1216 | of the following formats: unix:d[.s], :d[.s], ::d[.s] */ | |
1217 | if (strncmp(display, "unix:", 5) == 0 || | |
1218 | display[0] == ':') | |
1219 | { | |
1220 | /* Connect to the unix domain socket. */ | |
1221 | if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) | |
1222 | { | |
1223 | error("Could not parse display number from DISPLAY: %.100s", | |
1224 | display); | |
1225 | goto fail; | |
1226 | } | |
1227 | /* Create a socket. */ | |
1228 | sock = connect_local_xsocket(display_number); | |
1229 | if (sock < 0) | |
1230 | goto fail; | |
1231 | ||
1232 | /* OK, we now have a connection to the display. */ | |
1233 | goto success; | |
1234 | } | |
1235 | ||
1236 | /* Connect to an inet socket. The DISPLAY value is supposedly | |
1237 | hostname:d[.s], where hostname may also be numeric IP address. */ | |
1238 | strncpy(buf, display, sizeof(buf)); | |
1239 | buf[sizeof(buf) - 1] = 0; | |
1240 | cp = strchr(buf, ':'); | |
1241 | if (!cp) | |
1242 | { | |
1243 | error("Could not find ':' in DISPLAY: %.100s", display); | |
1244 | goto fail; | |
1245 | } | |
1246 | *cp = 0; | |
1247 | /* buf now contains the host name. But first we parse the display number. */ | |
1248 | if (sscanf(cp + 1, "%d", &display_number) != 1) | |
1249 | { | |
1250 | error("Could not parse display number from DISPLAY: %.100s", | |
1251 | display); | |
1252 | goto fail; | |
1253 | } | |
1254 | ||
1255 | /* Try to parse the host name as a numeric IP address. */ | |
1256 | memset(&sin, 0, sizeof(sin)); | |
1257 | sin.sin_addr.s_addr = inet_addr(buf); | |
1258 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) | |
1259 | { | |
1260 | /* It was a valid numeric host address. */ | |
1261 | sin.sin_family = AF_INET; | |
1262 | } | |
1263 | else | |
1264 | { | |
1265 | /* Not a numeric IP address. */ | |
1266 | /* Look up the host address from the name servers. */ | |
1267 | hp = gethostbyname(buf); | |
1268 | if (!hp) | |
1269 | { | |
1270 | error("%.100s: unknown host.", buf); | |
1271 | goto fail; | |
1272 | } | |
1273 | if (!hp->h_addr_list[0]) | |
1274 | { | |
1275 | error("%.100s: host has no IP address.", buf); | |
1276 | goto fail; | |
1277 | } | |
1278 | sin.sin_family = hp->h_addrtype; | |
1279 | memcpy(&sin.sin_addr, hp->h_addr_list[0], | |
1280 | sizeof(sin.sin_addr)); | |
1281 | } | |
1282 | /* Set port number. */ | |
1283 | sin.sin_port = htons(6000 + display_number); | |
1284 | ||
1285 | /* Create a socket. */ | |
1286 | sock = socket(sin.sin_family, SOCK_STREAM, 0); | |
1287 | if (sock < 0) | |
1288 | { | |
1289 | error("socket: %.100s", strerror(errno)); | |
1290 | goto fail; | |
1291 | } | |
1292 | /* Connect it to the display. */ | |
1293 | if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
1294 | { | |
1295 | error("connect %.100s:%d: %.100s", buf, 6000 + display_number, | |
1296 | strerror(errno)); | |
1297 | close(sock); | |
1298 | goto fail; | |
1299 | } | |
1300 | ||
1301 | success: | |
1302 | /* We have successfully obtained a connection to the real X display. */ | |
1303 | ||
1304 | /* Allocate a channel for this connection. */ | |
1305 | if (x11_saved_proto == NULL) | |
1306 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); | |
1307 | else | |
1308 | newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host); | |
1309 | channels[newch].remote_id = remote_channel; | |
1310 | ||
1311 | /* Send a confirmation to the remote host. */ | |
1312 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1313 | packet_put_int(remote_channel); | |
1314 | packet_put_int(newch); | |
1315 | packet_send(); | |
1316 | ||
1317 | return; | |
1318 | ||
1319 | fail: | |
1320 | /* Send refusal to the remote host. */ | |
1321 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1322 | packet_put_int(remote_channel); | |
1323 | packet_send(); | |
1324 | } | |
1325 | ||
1326 | /* Requests forwarding of X11 connections, generates fake authentication | |
1327 | data, and enables authentication spoofing. */ | |
1328 | ||
1329 | void x11_request_forwarding_with_spoofing(const char *proto, const char *data) | |
1330 | { | |
1331 | unsigned int data_len = (unsigned int)strlen(data) / 2; | |
1332 | unsigned int i, value; | |
1333 | char *new_data; | |
1334 | int screen_number; | |
1335 | const char *cp; | |
1336 | u_int32_t rand = 0; | |
1337 | ||
1338 | cp = getenv("DISPLAY"); | |
1339 | if (cp) | |
1340 | cp = strchr(cp, ':'); | |
1341 | if (cp) | |
1342 | cp = strchr(cp, '.'); | |
1343 | if (cp) | |
1344 | screen_number = atoi(cp + 1); | |
1345 | else | |
1346 | screen_number = 0; | |
1347 | ||
1348 | /* Save protocol name. */ | |
1349 | x11_saved_proto = xstrdup(proto); | |
1350 | ||
1351 | /* Extract real authentication data and generate fake data of the same | |
1352 | length. */ | |
1353 | x11_saved_data = xmalloc(data_len); | |
1354 | x11_fake_data = xmalloc(data_len); | |
1355 | for (i = 0; i < data_len; i++) | |
1356 | { | |
1357 | if (sscanf(data + 2 * i, "%2x", &value) != 1) | |
1358 | fatal("x11_request_forwarding: bad authentication data: %.100s", data); | |
1359 | if (i % 4 == 0) | |
1360 | rand = arc4random(); | |
1361 | x11_saved_data[i] = value; | |
1362 | x11_fake_data[i] = rand & 0xff; | |
1363 | rand >>= 8; | |
1364 | } | |
1365 | x11_saved_data_len = data_len; | |
1366 | x11_fake_data_len = data_len; | |
1367 | ||
1368 | /* Convert the fake data into hex. */ | |
1369 | new_data = xmalloc(2 * data_len + 1); | |
1370 | for (i = 0; i < data_len; i++) | |
1371 | sprintf(new_data + 2 * i, "%02x", (unsigned char)x11_fake_data[i]); | |
1372 | ||
1373 | /* Send the request packet. */ | |
1374 | packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); | |
1375 | packet_put_string(proto, strlen(proto)); | |
1376 | packet_put_string(new_data, strlen(new_data)); | |
1377 | packet_put_int(screen_number); | |
1378 | packet_send(); | |
1379 | packet_write_wait(); | |
1380 | xfree(new_data); | |
1381 | } | |
1382 | ||
1383 | /* Sends a message to the server to request authentication fd forwarding. */ | |
1384 | ||
1385 | void auth_request_forwarding() | |
1386 | { | |
1387 | packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); | |
1388 | packet_send(); | |
1389 | packet_write_wait(); | |
1390 | } | |
1391 | ||
1392 | /* Returns the name of the forwarded authentication socket. Returns NULL | |
1393 | if there is no forwarded authentication socket. The returned value | |
1394 | points to a static buffer. */ | |
1395 | ||
1396 | char *auth_get_socket_name() | |
1397 | { | |
1398 | return channel_forwarded_auth_socket_name; | |
1399 | } | |
1400 | ||
1401 | /* removes the agent forwarding socket */ | |
1402 | ||
1403 | void cleanup_socket(void) { | |
1404 | remove(channel_forwarded_auth_socket_name); | |
1405 | rmdir(channel_forwarded_auth_socket_dir); | |
1406 | } | |
1407 | ||
1408 | /* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. | |
1409 | This starts forwarding authentication requests. */ | |
1410 | ||
1411 | void auth_input_request_forwarding(struct passwd *pw) | |
1412 | { | |
1413 | int sock, newch; | |
1414 | struct sockaddr_un sunaddr; | |
1415 | ||
1416 | if (auth_get_socket_name() != NULL) | |
1417 | fatal("Protocol error: authentication forwarding requested twice."); | |
1418 | ||
1419 | /* Temporarily drop privileged uid for mkdir/bind. */ | |
1420 | temporarily_use_uid(pw->pw_uid); | |
1421 | ||
1422 | /* Allocate a buffer for the socket name, and format the name. */ | |
1423 | channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); | |
1424 | channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); | |
1425 | strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); | |
1426 | ||
1427 | /* Create private directory for socket */ | |
1428 | if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) | |
1429 | packet_disconnect("mkdtemp: %.100s", strerror(errno)); | |
1430 | snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, | |
1431 | "%s/agent.%d", channel_forwarded_auth_socket_dir, (int)getpid()); | |
1432 | ||
1433 | if (atexit(cleanup_socket) < 0) { | |
1434 | int saved=errno; | |
1435 | cleanup_socket(); | |
1436 | packet_disconnect("socket: %.100s", strerror(saved)); | |
1437 | } | |
1438 | ||
1439 | /* Create the socket. */ | |
1440 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
1441 | if (sock < 0) | |
1442 | packet_disconnect("socket: %.100s", strerror(errno)); | |
1443 | ||
1444 | /* Bind it to the name. */ | |
1445 | memset(&sunaddr, 0, sizeof(sunaddr)); | |
1446 | sunaddr.sun_family = AF_UNIX; | |
1447 | strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name, | |
1448 | sizeof(sunaddr.sun_path)); | |
1449 | ||
1450 | if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) | |
1451 | packet_disconnect("bind: %.100s", strerror(errno)); | |
1452 | ||
1453 | /* Restore the privileged uid. */ | |
1454 | restore_uid(); | |
1455 | ||
1456 | /* Start listening on the socket. */ | |
1457 | if (listen(sock, 5) < 0) | |
1458 | packet_disconnect("listen: %.100s", strerror(errno)); | |
1459 | ||
1460 | /* Allocate a channel for the authentication agent socket. */ | |
1461 | newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, | |
1462 | xstrdup("auth socket")); | |
1463 | strcpy(channels[newch].path, channel_forwarded_auth_socket_name); | |
1464 | } | |
1465 | ||
1466 | /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ | |
1467 | ||
1468 | void auth_input_open_request() | |
1469 | { | |
1470 | int remch, sock, newch; | |
1471 | char *dummyname; | |
1472 | ||
1473 | /* Read the remote channel number from the message. */ | |
1474 | remch = packet_get_int(); | |
1475 | ||
1476 | /* Get a connection to the local authentication agent (this may again get | |
1477 | forwarded). */ | |
1478 | sock = ssh_get_authentication_socket(); | |
1479 | ||
1480 | /* If we could not connect the agent, send an error message back to | |
1481 | the server. This should never happen unless the agent | |
1482 | dies, because authentication forwarding is only enabled if we have an | |
1483 | agent. */ | |
1484 | if (sock < 0){ | |
1485 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); | |
1486 | packet_put_int(remch); | |
1487 | packet_send(); | |
1488 | return; | |
1489 | } | |
1490 | ||
1491 | debug("Forwarding authentication connection."); | |
1492 | ||
1493 | /* Dummy host name. This will be freed when the channel is freed; it will | |
1494 | still be valid in the packet_put_string below since the channel cannot | |
1495 | yet be freed at that point. */ | |
1496 | dummyname = xstrdup("authentication agent connection"); | |
1497 | ||
1498 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); | |
1499 | channels[newch].remote_id = remch; | |
1500 | ||
1501 | /* Send a confirmation to the remote host. */ | |
1502 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); | |
1503 | packet_put_int(remch); | |
1504 | packet_put_int(newch); | |
1505 | packet_send(); | |
1506 | } |