Annotation of src/usr.bin/ssh/channels.c, Revision 1.32
1.1 deraadt 1: /*
1.26 deraadt 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: */
1.1 deraadt 17:
18: #include "includes.h"
1.32 ! deraadt 19: RCSID("$Id: channels.c,v 1.31 1999/12/01 13:59:15 markus Exp $");
1.1 deraadt 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"
1.20 markus 27: #include "readconf.h"
1.3 deraadt 28: #include "servconf.h"
1.1 deraadt 29:
1.14 markus 30: #include "channels.h"
31: #include "nchan.h"
32: #include "compat.h"
33:
1.1 deraadt 34: /* Maximum number of fake X11 displays to try. */
35: #define MAX_DISPLAYS 1000
36:
1.12 markus 37: /* Max len of agent socket */
38: #define MAX_SOCKET_NAME 100
39:
1.27 markus 40: /*
41: * Pointer to an array containing all allocated channels. The array is
42: * dynamically extended as needed.
43: */
1.1 deraadt 44: static Channel *channels = NULL;
45:
1.27 markus 46: /*
47: * Size of the channel array. All slots of the array must always be
48: * initialized (at least the type field); unused slots are marked with type
49: * SSH_CHANNEL_FREE.
50: */
1.1 deraadt 51: static int channels_alloc = 0;
52:
1.27 markus 53: /*
54: * Maximum file descriptor value used in any of the channels. This is
55: * updated in channel_allocate.
56: */
1.1 deraadt 57: static int channel_max_fd_value = 0;
58:
1.12 markus 59: /* Name and directory of socket for authentication agent forwarding. */
1.1 deraadt 60: static char *channel_forwarded_auth_socket_name = NULL;
1.25 markus 61: static char *channel_forwarded_auth_socket_dir = NULL;
1.1 deraadt 62:
63: /* Saved X11 authentication protocol name. */
64: char *x11_saved_proto = NULL;
65:
66: /* Saved X11 authentication data. This is the real data. */
67: char *x11_saved_data = NULL;
68: unsigned int x11_saved_data_len = 0;
69:
1.27 markus 70: /*
71: * Fake X11 authentication data. This is what the server will be sending us;
72: * we should replace any occurrences of this by the real data.
73: */
1.1 deraadt 74: char *x11_fake_data = NULL;
75: unsigned int x11_fake_data_len;
76:
1.27 markus 77: /*
78: * Data structure for storing which hosts are permitted for forward requests.
79: * The local sides of any remote forwards are stored in this array to prevent
80: * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
81: * network (which might be behind a firewall).
82: */
1.25 markus 83: typedef struct {
84: char *host; /* Host name. */
1.31 markus 85: u_short port; /* Port number. */
1.1 deraadt 86: } ForwardPermission;
87:
88: /* List of all permitted host/port pairs to connect. */
89: static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
90: /* Number of permitted host/port pairs in the array. */
91: static int num_permitted_opens = 0;
1.27 markus 92: /*
93: * If this is true, all opens are permitted. This is the case on the server
94: * on which we have to trust the client anyway, and the user could do
95: * anything after logging in anyway.
96: */
1.1 deraadt 97: static int all_opens_permitted = 0;
98:
99: /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
100: static int have_hostname_in_open = 0;
101:
102: /* Sets specific protocol options. */
103:
1.25 markus 104: void
105: channel_set_options(int hostname_in_open)
1.1 deraadt 106: {
1.25 markus 107: have_hostname_in_open = hostname_in_open;
1.1 deraadt 108: }
109:
1.27 markus 110: /*
111: * Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually
112: * called by the server, because the user could connect to any port anyway,
113: * and the server has no way to know but to trust the client anyway.
114: */
1.1 deraadt 115:
1.25 markus 116: void
117: channel_permit_all_opens()
1.1 deraadt 118: {
1.25 markus 119: all_opens_permitted = 1;
1.1 deraadt 120: }
121:
1.27 markus 122: /*
123: * Allocate a new channel object and set its type and socket. This will cause
124: * remote_name to be freed.
125: */
1.1 deraadt 126:
1.25 markus 127: int
128: channel_allocate(int type, int sock, char *remote_name)
1.1 deraadt 129: {
1.25 markus 130: int i, found;
131: Channel *c;
1.1 deraadt 132:
1.25 markus 133: /* Update the maximum file descriptor value. */
134: if (sock > channel_max_fd_value)
135: channel_max_fd_value = sock;
1.27 markus 136: /* XXX set close-on-exec -markus */
1.25 markus 137:
138: /* Do initial allocation if this is the first call. */
139: if (channels_alloc == 0) {
140: channels_alloc = 10;
141: channels = xmalloc(channels_alloc * sizeof(Channel));
142: for (i = 0; i < channels_alloc; i++)
143: channels[i].type = SSH_CHANNEL_FREE;
1.27 markus 144: /*
145: * Kludge: arrange a call to channel_stop_listening if we
146: * terminate with fatal().
147: */
1.25 markus 148: fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
149: }
150: /* Try to find a free slot where to put the new channel. */
151: for (found = -1, i = 0; i < channels_alloc; i++)
152: if (channels[i].type == SSH_CHANNEL_FREE) {
153: /* Found a free slot. */
154: found = i;
155: break;
156: }
157: if (found == -1) {
1.27 markus 158: /* There are no free slots. Take last+1 slot and expand the array. */
1.25 markus 159: found = channels_alloc;
160: channels_alloc += 10;
161: debug("channel: expanding %d", channels_alloc);
162: channels = xrealloc(channels, channels_alloc * sizeof(Channel));
163: for (i = found; i < channels_alloc; i++)
164: channels[i].type = SSH_CHANNEL_FREE;
165: }
166: /* Initialize and return new channel number. */
167: c = &channels[found];
168: buffer_init(&c->input);
169: buffer_init(&c->output);
170: chan_init_iostates(c);
171: c->self = found;
172: c->type = type;
173: c->sock = sock;
174: c->remote_id = -1;
175: c->remote_name = remote_name;
176: debug("channel %d: new [%s]", found, remote_name);
177: return found;
1.1 deraadt 178: }
179:
180: /* Free the channel and close its socket. */
181:
1.25 markus 182: void
183: channel_free(int channel)
1.1 deraadt 184: {
1.25 markus 185: if (channel < 0 || channel >= channels_alloc ||
186: channels[channel].type == SSH_CHANNEL_FREE)
187: packet_disconnect("channel free: bad local channel %d", channel);
188:
189: if (compat13)
190: shutdown(channels[channel].sock, SHUT_RDWR);
191: close(channels[channel].sock);
192: buffer_free(&channels[channel].input);
193: buffer_free(&channels[channel].output);
194: channels[channel].type = SSH_CHANNEL_FREE;
195: if (channels[channel].remote_name) {
196: xfree(channels[channel].remote_name);
197: channels[channel].remote_name = NULL;
198: }
1.1 deraadt 199: }
200:
1.27 markus 201: /*
202: * This is called just before select() to add any bits relevant to channels
203: * in the select bitmasks.
204: */
1.1 deraadt 205:
1.25 markus 206: void
207: channel_prepare_select(fd_set * readset, fd_set * writeset)
1.1 deraadt 208: {
1.25 markus 209: int i;
210: Channel *ch;
211: unsigned char *ucp;
212: unsigned int proto_len, data_len;
213:
214: for (i = 0; i < channels_alloc; i++) {
215: ch = &channels[i];
216: redo:
217: switch (ch->type) {
218: case SSH_CHANNEL_X11_LISTENER:
219: case SSH_CHANNEL_PORT_LISTENER:
220: case SSH_CHANNEL_AUTH_SOCKET:
221: FD_SET(ch->sock, readset);
222: break;
223:
224: case SSH_CHANNEL_OPEN:
225: if (compat13) {
226: if (buffer_len(&ch->input) < packet_get_maxsize())
227: FD_SET(ch->sock, readset);
228: if (buffer_len(&ch->output) > 0)
229: FD_SET(ch->sock, writeset);
230: break;
231: }
232: /* test whether sockets are 'alive' for read/write */
233: if (ch->istate == CHAN_INPUT_OPEN)
234: if (buffer_len(&ch->input) < packet_get_maxsize())
235: FD_SET(ch->sock, readset);
236: if (ch->ostate == CHAN_OUTPUT_OPEN ||
237: ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
238: if (buffer_len(&ch->output) > 0) {
239: FD_SET(ch->sock, writeset);
240: } else if (ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
241: chan_obuf_empty(ch);
242: }
243: }
244: break;
245:
246: case SSH_CHANNEL_INPUT_DRAINING:
247: if (!compat13)
248: fatal("cannot happen: IN_DRAIN");
249: if (buffer_len(&ch->input) == 0) {
250: packet_start(SSH_MSG_CHANNEL_CLOSE);
251: packet_put_int(ch->remote_id);
252: packet_send();
253: ch->type = SSH_CHANNEL_CLOSED;
254: debug("Closing channel %d after input drain.", i);
255: break;
256: }
257: break;
258:
259: case SSH_CHANNEL_OUTPUT_DRAINING:
260: if (!compat13)
261: fatal("cannot happen: OUT_DRAIN");
262: if (buffer_len(&ch->output) == 0) {
263: channel_free(i);
264: break;
265: }
266: FD_SET(ch->sock, writeset);
267: break;
268:
269: case SSH_CHANNEL_X11_OPEN:
1.27 markus 270: /*
271: * This is a special state for X11 authentication
272: * spoofing. An opened X11 connection (when
273: * authentication spoofing is being done) remains in
274: * this state until the first packet has been
275: * completely read. The authentication data in that
276: * packet is then substituted by the real data if it
277: * matches the fake data, and the channel is put into
278: * normal mode.
279: */
1.25 markus 280: /* Check if the fixed size part of the packet is in buffer. */
281: if (buffer_len(&ch->output) < 12)
282: break;
283:
284: /* Parse the lengths of variable-length fields. */
285: ucp = (unsigned char *) buffer_ptr(&ch->output);
286: if (ucp[0] == 0x42) { /* Byte order MSB first. */
287: proto_len = 256 * ucp[6] + ucp[7];
288: data_len = 256 * ucp[8] + ucp[9];
289: } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
290: proto_len = ucp[6] + 256 * ucp[7];
291: data_len = ucp[8] + 256 * ucp[9];
292: } else {
293: debug("Initial X11 packet contains bad byte order byte: 0x%x",
294: ucp[0]);
295: ch->type = SSH_CHANNEL_OPEN;
296: goto reject;
297: }
298:
299: /* Check if the whole packet is in buffer. */
300: if (buffer_len(&ch->output) <
301: 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
302: break;
303:
304: /* Check if authentication protocol matches. */
305: if (proto_len != strlen(x11_saved_proto) ||
306: memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
307: debug("X11 connection uses different authentication protocol.");
308: ch->type = SSH_CHANNEL_OPEN;
309: goto reject;
310: }
311: /* Check if authentication data matches our fake data. */
312: if (data_len != x11_fake_data_len ||
313: memcmp(ucp + 12 + ((proto_len + 3) & ~3),
314: x11_fake_data, x11_fake_data_len) != 0) {
315: debug("X11 auth data does not match fake data.");
316: ch->type = SSH_CHANNEL_OPEN;
317: goto reject;
318: }
319: /* Check fake data length */
320: if (x11_fake_data_len != x11_saved_data_len) {
321: error("X11 fake_data_len %d != saved_data_len %d",
322: x11_fake_data_len, x11_saved_data_len);
323: ch->type = SSH_CHANNEL_OPEN;
324: goto reject;
325: }
1.27 markus 326: /*
327: * Received authentication protocol and data match
328: * our fake data. Substitute the fake data with real
329: * data.
330: */
1.25 markus 331: memcpy(ucp + 12 + ((proto_len + 3) & ~3),
332: x11_saved_data, x11_saved_data_len);
333:
334: /* Start normal processing for the channel. */
335: ch->type = SSH_CHANNEL_OPEN;
336: goto redo;
337:
1.1 deraadt 338: reject:
1.27 markus 339: /*
340: * We have received an X11 connection that has bad
341: * authentication information.
342: */
1.25 markus 343: log("X11 connection rejected because of wrong authentication.\r\n");
344: buffer_clear(&ch->input);
345: buffer_clear(&ch->output);
346: if (compat13) {
347: close(ch->sock);
348: ch->sock = -1;
349: ch->type = SSH_CHANNEL_CLOSED;
350: packet_start(SSH_MSG_CHANNEL_CLOSE);
351: packet_put_int(ch->remote_id);
352: packet_send();
353: } else {
354: debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
355: chan_read_failed(ch);
356: chan_write_failed(ch);
357: debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
358: }
359: break;
360:
361: case SSH_CHANNEL_FREE:
362: default:
363: continue;
364: }
1.1 deraadt 365: }
366: }
367:
1.27 markus 368: /*
369: * After select, perform any appropriate operations for channels which have
370: * events pending.
371: */
1.1 deraadt 372:
1.25 markus 373: void
374: channel_after_select(fd_set * readset, fd_set * writeset)
1.1 deraadt 375: {
1.25 markus 376: struct sockaddr addr;
377: int addrlen, newsock, i, newch, len;
378: Channel *ch;
379: char buf[16384], *remote_hostname;
380:
381: /* Loop over all channels... */
382: for (i = 0; i < channels_alloc; i++) {
383: ch = &channels[i];
384: switch (ch->type) {
385: case SSH_CHANNEL_X11_LISTENER:
386: /* This is our fake X11 server socket. */
387: if (FD_ISSET(ch->sock, readset)) {
388: debug("X11 connection requested.");
389: addrlen = sizeof(addr);
390: newsock = accept(ch->sock, &addr, &addrlen);
391: if (newsock < 0) {
392: error("accept: %.100s", strerror(errno));
393: break;
394: }
395: remote_hostname = get_remote_hostname(newsock);
396: snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
397: remote_hostname, get_peer_port(newsock));
398: xfree(remote_hostname);
399: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
400: xstrdup(buf));
401: packet_start(SSH_SMSG_X11_OPEN);
402: packet_put_int(newch);
403: if (have_hostname_in_open)
404: packet_put_string(buf, strlen(buf));
405: packet_send();
406: }
407: break;
408:
409: case SSH_CHANNEL_PORT_LISTENER:
1.27 markus 410: /*
411: * This socket is listening for connections to a
412: * forwarded TCP/IP port.
413: */
1.25 markus 414: if (FD_ISSET(ch->sock, readset)) {
415: debug("Connection to port %d forwarding to %.100s:%d requested.",
416: ch->listening_port, ch->path, ch->host_port);
417: addrlen = sizeof(addr);
418: newsock = accept(ch->sock, &addr, &addrlen);
419: if (newsock < 0) {
420: error("accept: %.100s", strerror(errno));
421: break;
422: }
423: remote_hostname = get_remote_hostname(newsock);
424: snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d",
425: ch->listening_port, ch->path, ch->host_port,
426: remote_hostname, get_peer_port(newsock));
427: xfree(remote_hostname);
428: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
429: xstrdup(buf));
430: packet_start(SSH_MSG_PORT_OPEN);
431: packet_put_int(newch);
432: packet_put_string(ch->path, strlen(ch->path));
433: packet_put_int(ch->host_port);
434: if (have_hostname_in_open)
435: packet_put_string(buf, strlen(buf));
436: packet_send();
437: }
438: break;
439:
440: case SSH_CHANNEL_AUTH_SOCKET:
1.27 markus 441: /*
442: * This is the authentication agent socket listening
443: * for connections from clients.
444: */
1.25 markus 445: if (FD_ISSET(ch->sock, readset)) {
446: int nchan;
447: len = sizeof(addr);
448: newsock = accept(ch->sock, &addr, &len);
449: if (newsock < 0) {
450: error("accept from auth socket: %.100s", strerror(errno));
451: break;
452: }
453: nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock,
454: xstrdup("accepted auth socket"));
455: packet_start(SSH_SMSG_AGENT_OPEN);
456: packet_put_int(nchan);
457: packet_send();
458: }
459: break;
460:
461: case SSH_CHANNEL_OPEN:
1.27 markus 462: /*
463: * This is an open two-way communication channel. It
464: * is not of interest to us at this point what kind
465: * of data is being transmitted.
466: */
467:
468: /*
469: * Read available incoming data and append it to
470: * buffer; shutdown socket, if read or write failes
471: */
1.25 markus 472: if (FD_ISSET(ch->sock, readset)) {
473: len = read(ch->sock, buf, sizeof(buf));
474: if (len <= 0) {
475: if (compat13) {
476: buffer_consume(&ch->output, buffer_len(&ch->output));
477: ch->type = SSH_CHANNEL_INPUT_DRAINING;
478: debug("Channel %d status set to input draining.", i);
479: } else {
480: chan_read_failed(ch);
481: }
482: break;
483: }
484: buffer_append(&ch->input, buf, len);
485: }
486: /* Send buffered output data to the socket. */
487: if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
488: len = write(ch->sock, buffer_ptr(&ch->output),
489: buffer_len(&ch->output));
490: if (len <= 0) {
491: if (compat13) {
492: buffer_consume(&ch->output, buffer_len(&ch->output));
493: debug("Channel %d status set to input draining.", i);
494: ch->type = SSH_CHANNEL_INPUT_DRAINING;
495: } else {
496: chan_write_failed(ch);
497: }
498: break;
499: }
500: buffer_consume(&ch->output, len);
501: }
502: break;
503:
504: case SSH_CHANNEL_OUTPUT_DRAINING:
505: if (!compat13)
506: fatal("cannot happen: OUT_DRAIN");
507: /* Send buffered output data to the socket. */
508: if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
509: len = write(ch->sock, buffer_ptr(&ch->output),
510: buffer_len(&ch->output));
511: if (len <= 0)
512: buffer_consume(&ch->output, buffer_len(&ch->output));
513: else
514: buffer_consume(&ch->output, len);
515: }
516: break;
517:
518: case SSH_CHANNEL_X11_OPEN:
519: case SSH_CHANNEL_FREE:
520: default:
521: continue;
1.1 deraadt 522: }
523: }
524: }
525:
526: /* If there is data to send to the connection, send some of it now. */
527:
1.25 markus 528: void
529: channel_output_poll()
1.1 deraadt 530: {
1.25 markus 531: int len, i;
532: Channel *ch;
1.1 deraadt 533:
1.25 markus 534: for (i = 0; i < channels_alloc; i++) {
535: ch = &channels[i];
1.27 markus 536: /* We are only interested in channels that can have buffered incoming data. */
1.25 markus 537: if (ch->type != SSH_CHANNEL_OPEN &&
538: ch->type != SSH_CHANNEL_INPUT_DRAINING)
539: continue;
540:
541: /* Get the amount of buffered data for this channel. */
542: len = buffer_len(&ch->input);
543: if (len > 0) {
1.27 markus 544: /* Send some data for the other side over the secure connection. */
1.25 markus 545: if (packet_is_interactive()) {
546: if (len > 1024)
547: len = 512;
548: } else {
549: /* Keep the packets at reasonable size. */
550: if (len > 16384)
551: len = 16384;
552: }
553: packet_start(SSH_MSG_CHANNEL_DATA);
554: packet_put_int(ch->remote_id);
555: packet_put_string(buffer_ptr(&ch->input), len);
556: packet_send();
557: buffer_consume(&ch->input, len);
558: } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) {
559: if (compat13)
560: fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1.27 markus 561: /*
562: * input-buffer is empty and read-socket shutdown:
563: * tell peer, that we will not send more data: send IEOF
564: */
1.25 markus 565: chan_ibuf_empty(ch);
566: }
567: }
1.1 deraadt 568: }
569:
1.27 markus 570: /*
571: * This is called when a packet of type CHANNEL_DATA has just been received.
572: * The message type has already been consumed, but channel number and data is
573: * still there.
574: */
1.1 deraadt 575:
1.25 markus 576: void
577: channel_input_data(int payload_len)
1.1 deraadt 578: {
1.25 markus 579: int channel;
580: char *data;
581: unsigned int data_len;
582:
583: /* Get the channel number and verify it. */
584: channel = packet_get_int();
585: if (channel < 0 || channel >= channels_alloc ||
586: channels[channel].type == SSH_CHANNEL_FREE)
587: packet_disconnect("Received data for nonexistent channel %d.", channel);
588:
589: /* Ignore any data for non-open channels (might happen on close) */
590: if (channels[channel].type != SSH_CHANNEL_OPEN &&
591: channels[channel].type != SSH_CHANNEL_X11_OPEN)
592: return;
593:
594: /* Get the data. */
595: data = packet_get_string(&data_len);
596: packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA);
597: buffer_append(&channels[channel].output, data, data_len);
598: xfree(data);
1.1 deraadt 599: }
600:
1.27 markus 601: /*
602: * Returns true if no channel has too much buffered data, and false if one or
603: * more channel is overfull.
604: */
1.1 deraadt 605:
1.25 markus 606: int
607: channel_not_very_much_buffered_data()
1.1 deraadt 608: {
1.25 markus 609: unsigned int i;
610: Channel *ch;
611:
612: for (i = 0; i < channels_alloc; i++) {
613: ch = &channels[i];
614: switch (ch->type) {
615: case SSH_CHANNEL_X11_LISTENER:
616: case SSH_CHANNEL_PORT_LISTENER:
617: case SSH_CHANNEL_AUTH_SOCKET:
618: continue;
619: case SSH_CHANNEL_OPEN:
620: if (buffer_len(&ch->input) > packet_get_maxsize())
621: return 0;
622: if (buffer_len(&ch->output) > packet_get_maxsize())
623: return 0;
624: continue;
625: case SSH_CHANNEL_INPUT_DRAINING:
626: case SSH_CHANNEL_OUTPUT_DRAINING:
627: case SSH_CHANNEL_X11_OPEN:
628: case SSH_CHANNEL_FREE:
629: default:
630: continue;
631: }
1.1 deraadt 632: }
1.25 markus 633: return 1;
1.1 deraadt 634: }
635:
1.14 markus 636: /* This is called after receiving CHANNEL_CLOSE/IEOF. */
1.1 deraadt 637:
1.25 markus 638: void
639: channel_input_close()
1.1 deraadt 640: {
1.25 markus 641: int channel;
1.1 deraadt 642:
1.25 markus 643: /* Get the channel number and verify it. */
644: channel = packet_get_int();
645: if (channel < 0 || channel >= channels_alloc ||
646: channels[channel].type == SSH_CHANNEL_FREE)
647: packet_disconnect("Received data for nonexistent channel %d.", channel);
648:
649: if (!compat13) {
650: /* proto version 1.5 overloads CLOSE with IEOF */
651: chan_rcvd_ieof(&channels[channel]);
652: return;
653: }
1.27 markus 654:
655: /*
656: * Send a confirmation that we have closed the channel and no more
657: * data is coming for it.
658: */
1.25 markus 659: packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
660: packet_put_int(channels[channel].remote_id);
661: packet_send();
662:
1.27 markus 663: /*
664: * If the channel is in closed state, we have sent a close request,
665: * and the other side will eventually respond with a confirmation.
666: * Thus, we cannot free the channel here, because then there would be
667: * no-one to receive the confirmation. The channel gets freed when
668: * the confirmation arrives.
669: */
1.25 markus 670: if (channels[channel].type != SSH_CHANNEL_CLOSED) {
1.27 markus 671: /*
672: * Not a closed channel - mark it as draining, which will
673: * cause it to be freed later.
674: */
1.25 markus 675: buffer_consume(&channels[channel].input,
676: buffer_len(&channels[channel].input));
677: channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING;
678: }
1.1 deraadt 679: }
680:
1.14 markus 681: /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */
1.1 deraadt 682:
1.25 markus 683: void
684: channel_input_close_confirmation()
1.1 deraadt 685: {
1.25 markus 686: int channel;
1.1 deraadt 687:
1.25 markus 688: /* Get the channel number and verify it. */
689: channel = packet_get_int();
690: if (channel < 0 || channel >= channels_alloc)
691: packet_disconnect("Received close confirmation for out-of-range channel %d.",
692: channel);
693:
694: if (!compat13) {
695: /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
696: chan_rcvd_oclose(&channels[channel]);
697: return;
698: }
699: if (channels[channel].type != SSH_CHANNEL_CLOSED)
700: packet_disconnect("Received close confirmation for non-closed channel %d (type %d).",
701: channel, channels[channel].type);
1.1 deraadt 702:
1.25 markus 703: /* Free the channel. */
704: channel_free(channel);
1.1 deraadt 705: }
706:
707: /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
708:
1.25 markus 709: void
710: channel_input_open_confirmation()
1.1 deraadt 711: {
1.25 markus 712: int channel, remote_channel;
1.1 deraadt 713:
1.25 markus 714: /* Get the channel number and verify it. */
715: channel = packet_get_int();
716: if (channel < 0 || channel >= channels_alloc ||
717: channels[channel].type != SSH_CHANNEL_OPENING)
718: packet_disconnect("Received open confirmation for non-opening channel %d.",
719: channel);
720:
721: /* Get remote side's id for this channel. */
722: remote_channel = packet_get_int();
723:
1.27 markus 724: /* Record the remote channel number and mark that the channel is now open. */
1.25 markus 725: channels[channel].remote_id = remote_channel;
726: channels[channel].type = SSH_CHANNEL_OPEN;
1.1 deraadt 727: }
728:
729: /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
730:
1.25 markus 731: void
732: channel_input_open_failure()
1.1 deraadt 733: {
1.25 markus 734: int channel;
735:
736: /* Get the channel number and verify it. */
737: channel = packet_get_int();
738: if (channel < 0 || channel >= channels_alloc ||
739: channels[channel].type != SSH_CHANNEL_OPENING)
740: packet_disconnect("Received open failure for non-opening channel %d.",
741: channel);
1.1 deraadt 742:
1.25 markus 743: /* Free the channel. This will also close the socket. */
744: channel_free(channel);
1.1 deraadt 745: }
746:
1.27 markus 747: /*
748: * Stops listening for channels, and removes any unix domain sockets that we
749: * might have.
750: */
1.1 deraadt 751:
1.25 markus 752: void
753: channel_stop_listening()
1.1 deraadt 754: {
1.25 markus 755: int i;
756: for (i = 0; i < channels_alloc; i++) {
757: switch (channels[i].type) {
758: case SSH_CHANNEL_AUTH_SOCKET:
759: close(channels[i].sock);
760: remove(channels[i].path);
761: channel_free(i);
762: break;
763: case SSH_CHANNEL_PORT_LISTENER:
764: case SSH_CHANNEL_X11_LISTENER:
765: close(channels[i].sock);
766: channel_free(i);
767: break;
768: default:
769: break;
770: }
1.1 deraadt 771: }
772: }
773:
1.27 markus 774: /*
775: * Closes the sockets of all channels. This is used to close extra file
776: * descriptors after a fork.
777: */
1.1 deraadt 778:
1.25 markus 779: void
780: channel_close_all()
1.1 deraadt 781: {
1.25 markus 782: int i;
783: for (i = 0; i < channels_alloc; i++) {
784: if (channels[i].type != SSH_CHANNEL_FREE)
785: close(channels[i].sock);
786: }
1.1 deraadt 787: }
788:
789: /* Returns the maximum file descriptor number used by the channels. */
790:
1.25 markus 791: int
792: channel_max_fd()
1.1 deraadt 793: {
1.25 markus 794: return channel_max_fd_value;
1.1 deraadt 795: }
796:
797: /* Returns true if any channel is still open. */
798:
1.25 markus 799: int
800: channel_still_open()
1.1 deraadt 801: {
1.25 markus 802: unsigned int i;
803: for (i = 0; i < channels_alloc; i++)
804: switch (channels[i].type) {
805: case SSH_CHANNEL_FREE:
806: case SSH_CHANNEL_X11_LISTENER:
807: case SSH_CHANNEL_PORT_LISTENER:
808: case SSH_CHANNEL_CLOSED:
809: case SSH_CHANNEL_AUTH_SOCKET:
810: continue;
811: case SSH_CHANNEL_OPENING:
812: case SSH_CHANNEL_OPEN:
813: case SSH_CHANNEL_X11_OPEN:
814: return 1;
815: case SSH_CHANNEL_INPUT_DRAINING:
816: case SSH_CHANNEL_OUTPUT_DRAINING:
817: if (!compat13)
818: fatal("cannot happen: OUT_DRAIN");
819: return 1;
820: default:
821: fatal("channel_still_open: bad channel type %d", channels[i].type);
822: /* NOTREACHED */
823: }
824: return 0;
1.1 deraadt 825: }
826:
1.27 markus 827: /*
828: * Returns a message describing the currently open forwarded connections,
829: * suitable for sending to the client. The message contains crlf pairs for
830: * newlines.
831: */
1.1 deraadt 832:
1.25 markus 833: char *
834: channel_open_message()
1.1 deraadt 835: {
1.25 markus 836: Buffer buffer;
837: int i;
838: char buf[512], *cp;
839:
840: buffer_init(&buffer);
841: snprintf(buf, sizeof buf, "The following connections are open:\r\n");
1.1 deraadt 842: buffer_append(&buffer, buf, strlen(buf));
1.25 markus 843: for (i = 0; i < channels_alloc; i++) {
844: Channel *c = &channels[i];
845: switch (c->type) {
846: case SSH_CHANNEL_FREE:
847: case SSH_CHANNEL_X11_LISTENER:
848: case SSH_CHANNEL_PORT_LISTENER:
849: case SSH_CHANNEL_CLOSED:
850: case SSH_CHANNEL_AUTH_SOCKET:
851: continue;
852: case SSH_CHANNEL_OPENING:
853: case SSH_CHANNEL_OPEN:
854: case SSH_CHANNEL_X11_OPEN:
855: case SSH_CHANNEL_INPUT_DRAINING:
856: case SSH_CHANNEL_OUTPUT_DRAINING:
857: snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n",
858: c->self, c->remote_name,
859: c->type, c->remote_id, c->istate, c->ostate);
860: buffer_append(&buffer, buf, strlen(buf));
861: continue;
862: default:
863: fatal("channel_still_open: bad channel type %d", c->type);
864: /* NOTREACHED */
865: }
866: }
867: buffer_append(&buffer, "\0", 1);
868: cp = xstrdup(buffer_ptr(&buffer));
869: buffer_free(&buffer);
870: return cp;
1.1 deraadt 871: }
872:
1.27 markus 873: /*
874: * Initiate forwarding of connections to local port "port" through the secure
875: * channel to host:port from remote side.
876: */
1.1 deraadt 877:
1.25 markus 878: void
1.31 markus 879: channel_request_local_forwarding(u_short port, const char *host,
880: u_short host_port)
1.25 markus 881: {
1.28 markus 882: int ch, sock, on = 1;
1.25 markus 883: struct sockaddr_in sin;
884: extern Options options;
1.28 markus 885: struct linger linger;
1.25 markus 886:
887: if (strlen(host) > sizeof(channels[0].path) - 1)
888: packet_disconnect("Forward host name too long.");
889:
890: /* Create a port to listen for the host. */
891: sock = socket(AF_INET, SOCK_STREAM, 0);
892: if (sock < 0)
893: packet_disconnect("socket: %.100s", strerror(errno));
894:
895: /* Initialize socket address. */
896: memset(&sin, 0, sizeof(sin));
897: sin.sin_family = AF_INET;
898: if (options.gateway_ports == 1)
899: sin.sin_addr.s_addr = htonl(INADDR_ANY);
900: else
901: sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
902: sin.sin_port = htons(port);
1.28 markus 903:
904: /*
905: * Set socket options. We would like the socket to disappear as soon
906: * as it has been closed for whatever reason.
907: */
908: setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
909: linger.l_onoff = 1;
910: linger.l_linger = 5;
911: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1.25 markus 912:
913: /* Bind the socket to the address. */
914: if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0)
915: packet_disconnect("bind: %.100s", strerror(errno));
916:
917: /* Start listening for connections on the socket. */
918: if (listen(sock, 5) < 0)
919: packet_disconnect("listen: %.100s", strerror(errno));
920:
921: /* Allocate a channel number for the socket. */
922: ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
923: xstrdup("port listener"));
1.32 ! deraadt 924: strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
1.25 markus 925: channels[ch].host_port = host_port;
926: channels[ch].listening_port = port;
927: }
1.1 deraadt 928:
1.27 markus 929: /*
930: * Initiate forwarding of connections to port "port" on remote host through
931: * the secure channel to host:port from local side.
932: */
1.1 deraadt 933:
1.25 markus 934: void
1.31 markus 935: channel_request_remote_forwarding(u_short port, const char *host,
936: u_short remote_port)
1.25 markus 937: {
938: int payload_len;
939: /* Record locally that connection to this host/port is permitted. */
940: if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
941: fatal("channel_request_remote_forwarding: too many forwards");
942:
943: permitted_opens[num_permitted_opens].host = xstrdup(host);
944: permitted_opens[num_permitted_opens].port = remote_port;
945: num_permitted_opens++;
946:
947: /* Send the forward request to the remote side. */
948: packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
949: packet_put_int(port);
950: packet_put_string(host, strlen(host));
951: packet_put_int(remote_port);
952: packet_send();
953: packet_write_wait();
954:
1.27 markus 955: /*
956: * Wait for response from the remote side. It will send a disconnect
957: * message on failure, and we will never see it here.
958: */
1.25 markus 959: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1.1 deraadt 960: }
961:
1.27 markus 962: /*
963: * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
964: * listening for the port, and sends back a success reply (or disconnect
965: * message if there was an error). This never returns if there was an error.
966: */
1.1 deraadt 967:
1.25 markus 968: void
969: channel_input_port_forward_request(int is_root)
1.1 deraadt 970: {
1.31 markus 971: u_short port, host_port;
1.25 markus 972: char *hostname;
1.1 deraadt 973:
1.25 markus 974: /* Get arguments from the packet. */
975: port = packet_get_int();
976: hostname = packet_get_string(NULL);
977: host_port = packet_get_int();
978:
1.27 markus 979: /*
980: * Check that an unprivileged user is not trying to forward a
981: * privileged port.
982: */
1.25 markus 983: if (port < IPPORT_RESERVED && !is_root)
984: packet_disconnect("Requested forwarding of port %d but user is not root.",
985: port);
1.1 deraadt 986:
1.25 markus 987: /* Initiate forwarding. */
988: channel_request_local_forwarding(port, hostname, host_port);
989:
990: /* Free the argument string. */
991: xfree(hostname);
1.1 deraadt 992: }
993:
1.27 markus 994: /*
995: * This is called after receiving PORT_OPEN message. This attempts to
996: * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
997: * or CHANNEL_OPEN_FAILURE.
998: */
1.1 deraadt 999:
1.25 markus 1000: void
1001: channel_input_port_open(int payload_len)
1.1 deraadt 1002: {
1.31 markus 1003: int remote_channel, sock, newch, i;
1004: u_short host_port;
1.25 markus 1005: struct sockaddr_in sin;
1006: char *host, *originator_string;
1007: struct hostent *hp;
1008: int host_len, originator_len;
1009:
1010: /* Get remote channel number. */
1011: remote_channel = packet_get_int();
1012:
1013: /* Get host name to connect to. */
1014: host = packet_get_string(&host_len);
1015:
1016: /* Get port to connect to. */
1017: host_port = packet_get_int();
1018:
1019: /* Get remote originator name. */
1.29 markus 1020: if (have_hostname_in_open) {
1.25 markus 1021: originator_string = packet_get_string(&originator_len);
1.29 markus 1022: originator_len += 4; /* size of packet_int */
1023: } else {
1.25 markus 1024: originator_string = xstrdup("unknown (remote did not supply name)");
1.29 markus 1025: originator_len = 0; /* no originator supplied */
1026: }
1.25 markus 1027:
1028: packet_integrity_check(payload_len,
1.29 markus 1029: 4 + 4 + host_len + 4 + originator_len,
1.25 markus 1030: SSH_MSG_PORT_OPEN);
1031:
1032: /* Check if opening that port is permitted. */
1033: if (!all_opens_permitted) {
1034: /* Go trough all permitted ports. */
1035: for (i = 0; i < num_permitted_opens; i++)
1036: if (permitted_opens[i].port == host_port &&
1037: strcmp(permitted_opens[i].host, host) == 0)
1038: break;
1039:
1040: /* Check if we found the requested port among those permitted. */
1041: if (i >= num_permitted_opens) {
1042: /* The port is not permitted. */
1043: log("Received request to connect to %.100s:%d, but the request was denied.",
1044: host, host_port);
1045: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1046: packet_put_int(remote_channel);
1047: packet_send();
1048: }
1049: }
1050: memset(&sin, 0, sizeof(sin));
1051: sin.sin_addr.s_addr = inet_addr(host);
1052: if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) {
1053: /* It was a valid numeric host address. */
1054: sin.sin_family = AF_INET;
1055: } else {
1056: /* Look up the host address from the name servers. */
1057: hp = gethostbyname(host);
1058: if (!hp) {
1059: error("%.100s: unknown host.", host);
1060: goto fail;
1061: }
1062: if (!hp->h_addr_list[0]) {
1063: error("%.100s: host has no IP address.", host);
1064: goto fail;
1065: }
1066: sin.sin_family = hp->h_addrtype;
1067: memcpy(&sin.sin_addr, hp->h_addr_list[0],
1068: sizeof(sin.sin_addr));
1069: }
1070: sin.sin_port = htons(host_port);
1071:
1072: /* Create the socket. */
1073: sock = socket(sin.sin_family, SOCK_STREAM, 0);
1074: if (sock < 0) {
1075: error("socket: %.100s", strerror(errno));
1076: goto fail;
1077: }
1078: /* Connect to the host/port. */
1079: if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1080: error("connect %.100s:%d: %.100s", host, host_port,
1081: strerror(errno));
1082: close(sock);
1083: goto fail;
1084: }
1085: /* Successful connection. */
1086:
1087: /* Allocate a channel for this connection. */
1088: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1089: channels[newch].remote_id = remote_channel;
1090:
1091: /* Send a confirmation to the remote host. */
1092: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1093: packet_put_int(remote_channel);
1094: packet_put_int(newch);
1095: packet_send();
1096:
1097: /* Free the argument string. */
1098: xfree(host);
1099:
1100: return;
1101:
1102: fail:
1103: /* Free the argument string. */
1104: xfree(host);
1105:
1106: /* Send refusal to the remote host. */
1107: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1108: packet_put_int(remote_channel);
1109: packet_send();
1.1 deraadt 1110: }
1111:
1.27 markus 1112: /*
1113: * Creates an internet domain socket for listening for X11 connections.
1114: * Returns a suitable value for the DISPLAY variable, or NULL if an error
1115: * occurs.
1116: */
1.1 deraadt 1117:
1.25 markus 1118: char *
1119: x11_create_display_inet(int screen_number)
1.1 deraadt 1120: {
1.25 markus 1121: extern ServerOptions options;
1.31 markus 1122: int display_number, sock;
1123: u_short port;
1.25 markus 1124: struct sockaddr_in sin;
1125: char buf[512];
1126: char hostname[MAXHOSTNAMELEN];
1127:
1128: for (display_number = options.x11_display_offset;
1129: display_number < MAX_DISPLAYS;
1130: display_number++) {
1131: port = 6000 + display_number;
1132: memset(&sin, 0, sizeof(sin));
1133: sin.sin_family = AF_INET;
1134: sin.sin_addr.s_addr = htonl(INADDR_ANY);
1135: sin.sin_port = htons(port);
1136:
1137: sock = socket(AF_INET, SOCK_STREAM, 0);
1138: if (sock < 0) {
1139: error("socket: %.100s", strerror(errno));
1140: return NULL;
1141: }
1142: if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1143: debug("bind port %d: %.100s", port, strerror(errno));
1144: shutdown(sock, SHUT_RDWR);
1145: close(sock);
1146: continue;
1147: }
1148: break;
1149: }
1150: if (display_number >= MAX_DISPLAYS) {
1151: error("Failed to allocate internet-domain X11 display socket.");
1152: return NULL;
1153: }
1154: /* Start listening for connections on the socket. */
1155: if (listen(sock, 5) < 0) {
1156: error("listen: %.100s", strerror(errno));
1157: shutdown(sock, SHUT_RDWR);
1158: close(sock);
1159: return NULL;
1160: }
1161: /* Set up a suitable value for the DISPLAY variable. */
1162: if (gethostname(hostname, sizeof(hostname)) < 0)
1163: fatal("gethostname: %.100s", strerror(errno));
1164: snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname,
1165: display_number, screen_number);
1166:
1167: /* Allocate a channel for the socket. */
1168: (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
1169: xstrdup("X11 inet listener"));
1.1 deraadt 1170:
1.25 markus 1171: /* Return a suitable value for the DISPLAY environment variable. */
1172: return xstrdup(buf);
1.1 deraadt 1173: }
1174:
1175: #ifndef X_UNIX_PATH
1176: #define X_UNIX_PATH "/tmp/.X11-unix/X"
1177: #endif
1178:
1179: static
1180: int
1.30 deraadt 1181: connect_local_xsocket(unsigned int dnr)
1.1 deraadt 1182: {
1.25 markus 1183: static const char *const x_sockets[] = {
1184: X_UNIX_PATH "%u",
1185: "/var/X/.X11-unix/X" "%u",
1186: "/usr/spool/sockets/X11/" "%u",
1187: NULL
1188: };
1189: int sock;
1190: struct sockaddr_un addr;
1191: const char *const * path;
1192:
1193: for (path = x_sockets; *path; ++path) {
1194: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1195: if (sock < 0)
1196: error("socket: %.100s", strerror(errno));
1197: memset(&addr, 0, sizeof(addr));
1198: addr.sun_family = AF_UNIX;
1199: snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
1200: if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
1201: return sock;
1202: close(sock);
1203: }
1204: error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
1205: return -1;
1.1 deraadt 1206: }
1207:
1208:
1.27 markus 1209: /*
1210: * This is called when SSH_SMSG_X11_OPEN is received. The packet contains
1211: * the remote channel number. We should do whatever we want, and respond
1212: * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
1213: */
1.1 deraadt 1214:
1.25 markus 1215: void
1216: x11_input_open(int payload_len)
1.1 deraadt 1217: {
1.25 markus 1218: int remote_channel, display_number, sock, newch;
1219: const char *display;
1220: struct sockaddr_in sin;
1221: char buf[1024], *cp, *remote_host;
1222: struct hostent *hp;
1223: int remote_len;
1224:
1225: /* Get remote channel number. */
1226: remote_channel = packet_get_int();
1227:
1228: /* Get remote originator name. */
1.29 markus 1229: if (have_hostname_in_open) {
1.25 markus 1230: remote_host = packet_get_string(&remote_len);
1.29 markus 1231: remote_len += 4;
1232: } else {
1.25 markus 1233: remote_host = xstrdup("unknown (remote did not supply name)");
1.29 markus 1234: remote_len = 0;
1235: }
1.25 markus 1236:
1237: debug("Received X11 open request.");
1.29 markus 1238: packet_integrity_check(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN);
1.25 markus 1239:
1240: /* Try to open a socket for the local X server. */
1241: display = getenv("DISPLAY");
1242: if (!display) {
1243: error("DISPLAY not set.");
1244: goto fail;
1245: }
1.27 markus 1246: /*
1247: * Now we decode the value of the DISPLAY variable and make a
1248: * connection to the real X server.
1249: */
1250:
1251: /*
1252: * Check if it is a unix domain socket. Unix domain displays are in
1253: * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
1254: */
1.25 markus 1255: if (strncmp(display, "unix:", 5) == 0 ||
1256: display[0] == ':') {
1257: /* Connect to the unix domain socket. */
1258: if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
1259: error("Could not parse display number from DISPLAY: %.100s",
1260: display);
1261: goto fail;
1262: }
1263: /* Create a socket. */
1264: sock = connect_local_xsocket(display_number);
1265: if (sock < 0)
1266: goto fail;
1267:
1268: /* OK, we now have a connection to the display. */
1269: goto success;
1270: }
1.27 markus 1271: /*
1272: * Connect to an inet socket. The DISPLAY value is supposedly
1273: * hostname:d[.s], where hostname may also be numeric IP address.
1274: */
1.25 markus 1275: strncpy(buf, display, sizeof(buf));
1276: buf[sizeof(buf) - 1] = 0;
1277: cp = strchr(buf, ':');
1278: if (!cp) {
1279: error("Could not find ':' in DISPLAY: %.100s", display);
1280: goto fail;
1281: }
1282: *cp = 0;
1.27 markus 1283: /* buf now contains the host name. But first we parse the display number. */
1.25 markus 1284: if (sscanf(cp + 1, "%d", &display_number) != 1) {
1285: error("Could not parse display number from DISPLAY: %.100s",
1286: display);
1287: goto fail;
1288: }
1289: /* Try to parse the host name as a numeric IP address. */
1290: memset(&sin, 0, sizeof(sin));
1291: sin.sin_addr.s_addr = inet_addr(buf);
1292: if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) {
1293: /* It was a valid numeric host address. */
1294: sin.sin_family = AF_INET;
1295: } else {
1296: /* Not a numeric IP address. */
1297: /* Look up the host address from the name servers. */
1298: hp = gethostbyname(buf);
1299: if (!hp) {
1300: error("%.100s: unknown host.", buf);
1301: goto fail;
1302: }
1303: if (!hp->h_addr_list[0]) {
1304: error("%.100s: host has no IP address.", buf);
1305: goto fail;
1306: }
1307: sin.sin_family = hp->h_addrtype;
1308: memcpy(&sin.sin_addr, hp->h_addr_list[0],
1309: sizeof(sin.sin_addr));
1310: }
1311: /* Set port number. */
1312: sin.sin_port = htons(6000 + display_number);
1313:
1314: /* Create a socket. */
1315: sock = socket(sin.sin_family, SOCK_STREAM, 0);
1316: if (sock < 0) {
1317: error("socket: %.100s", strerror(errno));
1318: goto fail;
1319: }
1320: /* Connect it to the display. */
1321: if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1322: error("connect %.100s:%d: %.100s", buf, 6000 + display_number,
1323: strerror(errno));
1324: close(sock);
1325: goto fail;
1326: }
1327: success:
1328: /* We have successfully obtained a connection to the real X display. */
1329:
1330: /* Allocate a channel for this connection. */
1331: if (x11_saved_proto == NULL)
1332: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1333: else
1334: newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1335: channels[newch].remote_id = remote_channel;
1336:
1337: /* Send a confirmation to the remote host. */
1338: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1339: packet_put_int(remote_channel);
1340: packet_put_int(newch);
1341: packet_send();
1342:
1343: return;
1344:
1345: fail:
1346: /* Send refusal to the remote host. */
1347: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1348: packet_put_int(remote_channel);
1349: packet_send();
1.1 deraadt 1350: }
1351:
1.27 markus 1352: /*
1353: * Requests forwarding of X11 connections, generates fake authentication
1354: * data, and enables authentication spoofing.
1355: */
1.1 deraadt 1356:
1.25 markus 1357: void
1358: x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1.1 deraadt 1359: {
1.25 markus 1360: unsigned int data_len = (unsigned int) strlen(data) / 2;
1361: unsigned int i, value;
1362: char *new_data;
1363: int screen_number;
1364: const char *cp;
1365: u_int32_t rand = 0;
1366:
1367: cp = getenv("DISPLAY");
1368: if (cp)
1369: cp = strchr(cp, ':');
1370: if (cp)
1371: cp = strchr(cp, '.');
1372: if (cp)
1373: screen_number = atoi(cp + 1);
1374: else
1375: screen_number = 0;
1376:
1377: /* Save protocol name. */
1378: x11_saved_proto = xstrdup(proto);
1379:
1.27 markus 1380: /*
1381: * Extract real authentication data and generate fake data of the
1382: * same length.
1383: */
1.25 markus 1384: x11_saved_data = xmalloc(data_len);
1385: x11_fake_data = xmalloc(data_len);
1386: for (i = 0; i < data_len; i++) {
1387: if (sscanf(data + 2 * i, "%2x", &value) != 1)
1388: fatal("x11_request_forwarding: bad authentication data: %.100s", data);
1389: if (i % 4 == 0)
1390: rand = arc4random();
1391: x11_saved_data[i] = value;
1392: x11_fake_data[i] = rand & 0xff;
1393: rand >>= 8;
1394: }
1395: x11_saved_data_len = data_len;
1396: x11_fake_data_len = data_len;
1397:
1398: /* Convert the fake data into hex. */
1399: new_data = xmalloc(2 * data_len + 1);
1400: for (i = 0; i < data_len; i++)
1401: sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]);
1402:
1403: /* Send the request packet. */
1404: packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
1405: packet_put_string(proto, strlen(proto));
1406: packet_put_string(new_data, strlen(new_data));
1407: packet_put_int(screen_number);
1408: packet_send();
1409: packet_write_wait();
1410: xfree(new_data);
1.1 deraadt 1411: }
1412:
1413: /* Sends a message to the server to request authentication fd forwarding. */
1414:
1.25 markus 1415: void
1416: auth_request_forwarding()
1.1 deraadt 1417: {
1.25 markus 1418: packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
1419: packet_send();
1420: packet_write_wait();
1.1 deraadt 1421: }
1422:
1.27 markus 1423: /*
1424: * Returns the name of the forwarded authentication socket. Returns NULL if
1425: * there is no forwarded authentication socket. The returned value points to
1426: * a static buffer.
1427: */
1.1 deraadt 1428:
1.25 markus 1429: char *
1430: auth_get_socket_name()
1.1 deraadt 1431: {
1.25 markus 1432: return channel_forwarded_auth_socket_name;
1.1 deraadt 1433: }
1434:
1.12 markus 1435: /* removes the agent forwarding socket */
1436:
1.25 markus 1437: void
1438: cleanup_socket(void)
1439: {
1440: remove(channel_forwarded_auth_socket_name);
1441: rmdir(channel_forwarded_auth_socket_dir);
1.12 markus 1442: }
1443:
1.27 markus 1444: /*
1445: * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
1446: * This starts forwarding authentication requests.
1447: */
1.1 deraadt 1448:
1.25 markus 1449: void
1450: auth_input_request_forwarding(struct passwd * pw)
1.1 deraadt 1451: {
1.25 markus 1452: int sock, newch;
1453: struct sockaddr_un sunaddr;
1454:
1455: if (auth_get_socket_name() != NULL)
1456: fatal("Protocol error: authentication forwarding requested twice.");
1457:
1458: /* Temporarily drop privileged uid for mkdir/bind. */
1459: temporarily_use_uid(pw->pw_uid);
1460:
1461: /* Allocate a buffer for the socket name, and format the name. */
1462: channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
1463: channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
1464: strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
1465:
1466: /* Create private directory for socket */
1467: if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
1468: packet_disconnect("mkdtemp: %.100s", strerror(errno));
1469: snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
1470: channel_forwarded_auth_socket_dir, (int) getpid());
1471:
1472: if (atexit(cleanup_socket) < 0) {
1473: int saved = errno;
1474: cleanup_socket();
1475: packet_disconnect("socket: %.100s", strerror(saved));
1476: }
1477: /* Create the socket. */
1478: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1479: if (sock < 0)
1480: packet_disconnect("socket: %.100s", strerror(errno));
1481:
1482: /* Bind it to the name. */
1483: memset(&sunaddr, 0, sizeof(sunaddr));
1484: sunaddr.sun_family = AF_UNIX;
1485: strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
1486: sizeof(sunaddr.sun_path));
1487:
1488: if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
1489: packet_disconnect("bind: %.100s", strerror(errno));
1490:
1491: /* Restore the privileged uid. */
1492: restore_uid();
1493:
1494: /* Start listening on the socket. */
1495: if (listen(sock, 5) < 0)
1496: packet_disconnect("listen: %.100s", strerror(errno));
1497:
1498: /* Allocate a channel for the authentication agent socket. */
1499: newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
1500: xstrdup("auth socket"));
1.32 ! deraadt 1501: strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
! 1502: sizeof(channels[newch].path));
1.1 deraadt 1503: }
1504:
1505: /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
1506:
1.25 markus 1507: void
1508: auth_input_open_request()
1.1 deraadt 1509: {
1.25 markus 1510: int remch, sock, newch;
1511: char *dummyname;
1512:
1513: /* Read the remote channel number from the message. */
1514: remch = packet_get_int();
1515:
1.27 markus 1516: /*
1517: * Get a connection to the local authentication agent (this may again
1518: * get forwarded).
1519: */
1.25 markus 1520: sock = ssh_get_authentication_socket();
1521:
1.27 markus 1522: /*
1523: * If we could not connect the agent, send an error message back to
1524: * the server. This should never happen unless the agent dies,
1525: * because authentication forwarding is only enabled if we have an
1526: * agent.
1527: */
1.25 markus 1528: if (sock < 0) {
1529: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1530: packet_put_int(remch);
1531: packet_send();
1532: return;
1533: }
1534: debug("Forwarding authentication connection.");
1.1 deraadt 1535:
1.27 markus 1536: /*
1537: * Dummy host name. This will be freed when the channel is freed; it
1538: * will still be valid in the packet_put_string below since the
1539: * channel cannot yet be freed at that point.
1540: */
1.25 markus 1541: dummyname = xstrdup("authentication agent connection");
1542:
1543: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
1544: channels[newch].remote_id = remch;
1545:
1546: /* Send a confirmation to the remote host. */
1547: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1548: packet_put_int(remch);
1549: packet_put_int(newch);
1550: packet_send();
1.1 deraadt 1551: }
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