Annotation of src/usr.bin/ssh/channels.c, Revision 1.35
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"
1.35 ! markus 19: RCSID("$Id: channels.c,v 1.34 1999/12/27 09:48:38 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;
1.34 markus 254: debug("Closing channel %d after input drain.", ch->self);
1.25 markus 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;
1.35 ! markus 377: int newsock, i, newch, len;
! 378: socklen_t addrlen;
1.25 markus 379: Channel *ch;
380: char buf[16384], *remote_hostname;
381:
382: /* Loop over all channels... */
383: for (i = 0; i < channels_alloc; i++) {
384: ch = &channels[i];
385: switch (ch->type) {
386: case SSH_CHANNEL_X11_LISTENER:
387: /* This is our fake X11 server socket. */
388: if (FD_ISSET(ch->sock, readset)) {
389: debug("X11 connection requested.");
390: addrlen = sizeof(addr);
391: newsock = accept(ch->sock, &addr, &addrlen);
392: if (newsock < 0) {
393: error("accept: %.100s", strerror(errno));
394: break;
395: }
396: remote_hostname = get_remote_hostname(newsock);
397: snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
398: remote_hostname, get_peer_port(newsock));
399: xfree(remote_hostname);
400: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
401: xstrdup(buf));
402: packet_start(SSH_SMSG_X11_OPEN);
403: packet_put_int(newch);
404: if (have_hostname_in_open)
405: packet_put_string(buf, strlen(buf));
406: packet_send();
407: }
408: break;
409:
410: case SSH_CHANNEL_PORT_LISTENER:
1.27 markus 411: /*
412: * This socket is listening for connections to a
413: * forwarded TCP/IP port.
414: */
1.25 markus 415: if (FD_ISSET(ch->sock, readset)) {
1.35 ! markus 416: debug("Connection to port %d forwarding to %.100s port %d requested.",
1.25 markus 417: ch->listening_port, ch->path, ch->host_port);
418: addrlen = sizeof(addr);
419: newsock = accept(ch->sock, &addr, &addrlen);
420: if (newsock < 0) {
421: error("accept: %.100s", strerror(errno));
422: break;
423: }
424: remote_hostname = get_remote_hostname(newsock);
1.35 ! markus 425: snprintf(buf, sizeof buf, "listen port %d for %.100s port %d, connect from %.200s port %d",
1.25 markus 426: ch->listening_port, ch->path, ch->host_port,
427: remote_hostname, get_peer_port(newsock));
428: xfree(remote_hostname);
429: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
430: xstrdup(buf));
431: packet_start(SSH_MSG_PORT_OPEN);
432: packet_put_int(newch);
433: packet_put_string(ch->path, strlen(ch->path));
434: packet_put_int(ch->host_port);
435: if (have_hostname_in_open)
436: packet_put_string(buf, strlen(buf));
437: packet_send();
438: }
439: break;
440:
441: case SSH_CHANNEL_AUTH_SOCKET:
1.27 markus 442: /*
443: * This is the authentication agent socket listening
444: * for connections from clients.
445: */
1.25 markus 446: if (FD_ISSET(ch->sock, readset)) {
1.34 markus 447: addrlen = sizeof(addr);
448: newsock = accept(ch->sock, &addr, &addrlen);
1.25 markus 449: if (newsock < 0) {
450: error("accept from auth socket: %.100s", strerror(errno));
451: break;
452: }
1.34 markus 453: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
1.25 markus 454: xstrdup("accepted auth socket"));
455: packet_start(SSH_SMSG_AGENT_OPEN);
1.34 markus 456: packet_put_int(newch);
1.25 markus 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. */
1.34 markus 550: if (len > packet_get_maxsize()/2)
551: len = packet_get_maxsize()/2;
1.25 markus 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,
1.33 markus 880: u_short host_port, int gateway_ports)
1.25 markus 881: {
1.35 ! markus 882: int success, ch, sock, on = 1;
! 883: struct addrinfo hints, *ai, *aitop;
! 884: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
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:
1.28 markus 890: /*
1.35 ! markus 891: * getaddrinfo returns a loopback address if the hostname is
! 892: * set to NULL and hints.ai_flags is not AI_PASSIVE
1.28 markus 893: */
1.35 ! markus 894: memset(&hints, 0, sizeof(hints));
! 895: hints.ai_family = IPv4or6;
! 896: hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
! 897: hints.ai_socktype = SOCK_STREAM;
! 898: snprintf(strport, sizeof strport, "%d", port);
! 899: if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
! 900: packet_disconnect("getaddrinfo: fatal error");
! 901:
! 902: success = 0;
! 903: for (ai = aitop; ai; ai = ai->ai_next) {
! 904: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
! 905: continue;
! 906: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
! 907: strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
! 908: error("channel_request_local_forwarding: getnameinfo failed");
! 909: continue;
! 910: }
! 911: /* Create a port to listen for the host. */
! 912: sock = socket(ai->ai_family, SOCK_STREAM, 0);
! 913: if (sock < 0) {
! 914: /* this is no error since kernel may not support ipv6 */
! 915: verbose("socket: %.100s", strerror(errno));
! 916: continue;
! 917: }
! 918: /*
! 919: * Set socket options. We would like the socket to disappear
! 920: * as soon as it has been closed for whatever reason.
! 921: */
! 922: setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
! 923: linger.l_onoff = 1;
! 924: linger.l_linger = 5;
! 925: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
! 926: debug("Local forwarding listening on %s port %s.", ntop, strport);
! 927:
! 928: /* Bind the socket to the address. */
! 929: if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
! 930: /* address can be in use ipv6 address is already bound */
! 931: verbose("bind: %.100s", strerror(errno));
! 932: close(sock);
! 933: continue;
! 934: }
! 935: /* Start listening for connections on the socket. */
! 936: if (listen(sock, 5) < 0) {
! 937: error("listen: %.100s", strerror(errno));
! 938: close(sock);
! 939: continue;
! 940: }
! 941: /* Allocate a channel number for the socket. */
! 942: ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
! 943: xstrdup("port listener"));
! 944: strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
! 945: channels[ch].host_port = host_port;
! 946: channels[ch].listening_port = port;
! 947: success = 1;
! 948: }
! 949: if (success == 0)
! 950: packet_disconnect("cannot listen port: %d", port);
! 951: freeaddrinfo(aitop);
1.25 markus 952: }
1.1 deraadt 953:
1.27 markus 954: /*
955: * Initiate forwarding of connections to port "port" on remote host through
956: * the secure channel to host:port from local side.
957: */
1.1 deraadt 958:
1.25 markus 959: void
1.31 markus 960: channel_request_remote_forwarding(u_short port, const char *host,
961: u_short remote_port)
1.25 markus 962: {
963: int payload_len;
964: /* Record locally that connection to this host/port is permitted. */
965: if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
966: fatal("channel_request_remote_forwarding: too many forwards");
967:
968: permitted_opens[num_permitted_opens].host = xstrdup(host);
969: permitted_opens[num_permitted_opens].port = remote_port;
970: num_permitted_opens++;
971:
972: /* Send the forward request to the remote side. */
973: packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
974: packet_put_int(port);
975: packet_put_string(host, strlen(host));
976: packet_put_int(remote_port);
977: packet_send();
978: packet_write_wait();
979:
1.27 markus 980: /*
981: * Wait for response from the remote side. It will send a disconnect
982: * message on failure, and we will never see it here.
983: */
1.25 markus 984: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1.1 deraadt 985: }
986:
1.27 markus 987: /*
988: * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
989: * listening for the port, and sends back a success reply (or disconnect
990: * message if there was an error). This never returns if there was an error.
991: */
1.1 deraadt 992:
1.25 markus 993: void
994: channel_input_port_forward_request(int is_root)
1.1 deraadt 995: {
1.31 markus 996: u_short port, host_port;
1.25 markus 997: char *hostname;
1.1 deraadt 998:
1.25 markus 999: /* Get arguments from the packet. */
1000: port = packet_get_int();
1001: hostname = packet_get_string(NULL);
1002: host_port = packet_get_int();
1003:
1.27 markus 1004: /*
1005: * Check that an unprivileged user is not trying to forward a
1006: * privileged port.
1007: */
1.25 markus 1008: if (port < IPPORT_RESERVED && !is_root)
1009: packet_disconnect("Requested forwarding of port %d but user is not root.",
1010: port);
1.33 markus 1011: /*
1012: * Initiate forwarding,
1013: * bind port to localhost only (gateway ports == 0).
1014: */
1015: channel_request_local_forwarding(port, hostname, host_port, 0);
1.25 markus 1016:
1017: /* Free the argument string. */
1018: xfree(hostname);
1.1 deraadt 1019: }
1020:
1.27 markus 1021: /*
1022: * This is called after receiving PORT_OPEN message. This attempts to
1023: * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
1024: * or CHANNEL_OPEN_FAILURE.
1025: */
1.1 deraadt 1026:
1.25 markus 1027: void
1028: channel_input_port_open(int payload_len)
1.1 deraadt 1029: {
1.35 ! markus 1030: int remote_channel, sock = 0, newch, i;
1.31 markus 1031: u_short host_port;
1.25 markus 1032: char *host, *originator_string;
1033: int host_len, originator_len;
1.35 ! markus 1034: struct addrinfo hints, *ai, *aitop;
! 1035: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
! 1036: int gaierr;
1.25 markus 1037:
1038: /* Get remote channel number. */
1039: remote_channel = packet_get_int();
1040:
1041: /* Get host name to connect to. */
1042: host = packet_get_string(&host_len);
1043:
1044: /* Get port to connect to. */
1045: host_port = packet_get_int();
1046:
1047: /* Get remote originator name. */
1.29 markus 1048: if (have_hostname_in_open) {
1.25 markus 1049: originator_string = packet_get_string(&originator_len);
1.29 markus 1050: originator_len += 4; /* size of packet_int */
1051: } else {
1.25 markus 1052: originator_string = xstrdup("unknown (remote did not supply name)");
1.29 markus 1053: originator_len = 0; /* no originator supplied */
1054: }
1.25 markus 1055:
1056: packet_integrity_check(payload_len,
1.29 markus 1057: 4 + 4 + host_len + 4 + originator_len,
1.25 markus 1058: SSH_MSG_PORT_OPEN);
1059:
1060: /* Check if opening that port is permitted. */
1061: if (!all_opens_permitted) {
1062: /* Go trough all permitted ports. */
1063: for (i = 0; i < num_permitted_opens; i++)
1064: if (permitted_opens[i].port == host_port &&
1065: strcmp(permitted_opens[i].host, host) == 0)
1066: break;
1067:
1068: /* Check if we found the requested port among those permitted. */
1069: if (i >= num_permitted_opens) {
1070: /* The port is not permitted. */
1071: log("Received request to connect to %.100s:%d, but the request was denied.",
1072: host, host_port);
1073: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1074: packet_put_int(remote_channel);
1075: packet_send();
1076: }
1077: }
1.35 ! markus 1078:
! 1079: memset(&hints, 0, sizeof(hints));
! 1080: hints.ai_family = IPv4or6;
! 1081: hints.ai_socktype = SOCK_STREAM;
! 1082: snprintf(strport, sizeof strport, "%d", host_port);
! 1083: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
! 1084: error("%.100s: unknown host (%s)", host, gai_strerror(gaierr));
! 1085: goto fail;
! 1086: }
! 1087:
! 1088: for (ai = aitop; ai; ai = ai->ai_next) {
! 1089: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
! 1090: continue;
! 1091: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
! 1092: strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
! 1093: error("channel_input_port_open: getnameinfo failed");
! 1094: continue;
! 1095: }
! 1096: /* Create the socket. */
! 1097: sock = socket(ai->ai_family, SOCK_STREAM, 0);
! 1098: if (sock < 0) {
! 1099: error("socket: %.100s", strerror(errno));
! 1100: continue;
1.25 markus 1101: }
1.35 ! markus 1102: /* Connect to the host/port. */
! 1103: if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
! 1104: error("connect %.100s port %s: %.100s", ntop, strport,
! 1105: strerror(errno));
! 1106: close(sock);
! 1107: continue; /* fail -- try next */
1.25 markus 1108: }
1.35 ! markus 1109: break; /* success */
! 1110:
1.25 markus 1111: }
1.35 ! markus 1112: freeaddrinfo(aitop);
! 1113:
! 1114: if (!ai) {
! 1115: error("connect %.100s port %d: failed.", host, host_port);
1.25 markus 1116: goto fail;
1117: }
1.35 ! markus 1118:
1.25 markus 1119: /* Successful connection. */
1120:
1121: /* Allocate a channel for this connection. */
1122: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1123: channels[newch].remote_id = remote_channel;
1124:
1125: /* Send a confirmation to the remote host. */
1126: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1127: packet_put_int(remote_channel);
1128: packet_put_int(newch);
1129: packet_send();
1130:
1131: /* Free the argument string. */
1132: xfree(host);
1133:
1134: return;
1135:
1136: fail:
1137: /* Free the argument string. */
1138: xfree(host);
1139:
1140: /* Send refusal to the remote host. */
1141: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1142: packet_put_int(remote_channel);
1143: packet_send();
1.1 deraadt 1144: }
1145:
1.27 markus 1146: /*
1147: * Creates an internet domain socket for listening for X11 connections.
1148: * Returns a suitable value for the DISPLAY variable, or NULL if an error
1149: * occurs.
1150: */
1.1 deraadt 1151:
1.35 ! markus 1152: #define NUM_SOCKS 10
! 1153:
1.25 markus 1154: char *
1.33 markus 1155: x11_create_display_inet(int screen_number, int x11_display_offset)
1.1 deraadt 1156: {
1.31 markus 1157: int display_number, sock;
1158: u_short port;
1.35 ! markus 1159: struct addrinfo hints, *ai, *aitop;
! 1160: char strport[NI_MAXSERV];
! 1161: int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
! 1162: char display[512];
1.25 markus 1163: char hostname[MAXHOSTNAMELEN];
1164:
1.33 markus 1165: for (display_number = x11_display_offset;
1.25 markus 1166: display_number < MAX_DISPLAYS;
1167: display_number++) {
1168: port = 6000 + display_number;
1.35 ! markus 1169: memset(&hints, 0, sizeof(hints));
! 1170: hints.ai_family = IPv4or6;
! 1171: hints.ai_flags = 0 /*AI_PASSIVE*/; /* XXX loopback only ? */
! 1172: hints.ai_socktype = SOCK_STREAM;
! 1173: snprintf(strport, sizeof strport, "%d", port);
! 1174: if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
! 1175: error("getaddrinfo: %.100s", gai_strerror(gaierr));
1.25 markus 1176: return NULL;
1177: }
1.35 ! markus 1178: for (ai = aitop; ai; ai = ai->ai_next) {
! 1179: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
! 1180: continue;
! 1181: sock = socket(ai->ai_family, SOCK_STREAM, 0);
! 1182: if (sock < 0) {
! 1183: error("socket: %.100s", strerror(errno));
! 1184: return NULL;
! 1185: }
! 1186: if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
! 1187: debug("bind port %d: %.100s", port, strerror(errno));
! 1188: shutdown(sock, SHUT_RDWR);
! 1189: close(sock);
! 1190: for (n = 0; n < num_socks; n++) {
! 1191: shutdown(socks[n], SHUT_RDWR);
! 1192: close(socks[n]);
! 1193: }
! 1194: num_socks = 0;
! 1195: break;
! 1196: }
! 1197: socks[num_socks++] = sock;
! 1198: if (num_socks == NUM_SOCKS)
! 1199: break;
1.25 markus 1200: }
1.35 ! markus 1201: if (num_socks > 0)
! 1202: break;
1.25 markus 1203: }
1204: if (display_number >= MAX_DISPLAYS) {
1205: error("Failed to allocate internet-domain X11 display socket.");
1206: return NULL;
1207: }
1208: /* Start listening for connections on the socket. */
1.35 ! markus 1209: for (n = 0; n < num_socks; n++) {
! 1210: sock = socks[n];
! 1211: if (listen(sock, 5) < 0) {
! 1212: error("listen: %.100s", strerror(errno));
! 1213: shutdown(sock, SHUT_RDWR);
! 1214: close(sock);
! 1215: return NULL;
! 1216: }
1.25 markus 1217: }
1.35 ! markus 1218:
1.25 markus 1219: /* Set up a suitable value for the DISPLAY variable. */
1220: if (gethostname(hostname, sizeof(hostname)) < 0)
1221: fatal("gethostname: %.100s", strerror(errno));
1.35 ! markus 1222: snprintf(display, sizeof display, "%.400s:%d.%d", hostname,
1.25 markus 1223: display_number, screen_number);
1224:
1.35 ! markus 1225: /* Allocate a channel for each socket. */
! 1226: for (n = 0; n < num_socks; n++) {
! 1227: sock = socks[n];
! 1228: (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
! 1229: xstrdup("X11 inet listener"));
! 1230: }
1.1 deraadt 1231:
1.25 markus 1232: /* Return a suitable value for the DISPLAY environment variable. */
1.35 ! markus 1233: return xstrdup(display);
1.1 deraadt 1234: }
1235:
1236: #ifndef X_UNIX_PATH
1237: #define X_UNIX_PATH "/tmp/.X11-unix/X"
1238: #endif
1239:
1240: static
1241: int
1.30 deraadt 1242: connect_local_xsocket(unsigned int dnr)
1.1 deraadt 1243: {
1.25 markus 1244: static const char *const x_sockets[] = {
1245: X_UNIX_PATH "%u",
1246: "/var/X/.X11-unix/X" "%u",
1247: "/usr/spool/sockets/X11/" "%u",
1248: NULL
1249: };
1250: int sock;
1251: struct sockaddr_un addr;
1252: const char *const * path;
1253:
1254: for (path = x_sockets; *path; ++path) {
1255: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1256: if (sock < 0)
1257: error("socket: %.100s", strerror(errno));
1258: memset(&addr, 0, sizeof(addr));
1259: addr.sun_family = AF_UNIX;
1260: snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
1261: if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
1262: return sock;
1263: close(sock);
1264: }
1265: error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
1266: return -1;
1.1 deraadt 1267: }
1268:
1269:
1.27 markus 1270: /*
1271: * This is called when SSH_SMSG_X11_OPEN is received. The packet contains
1272: * the remote channel number. We should do whatever we want, and respond
1273: * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
1274: */
1.1 deraadt 1275:
1.25 markus 1276: void
1277: x11_input_open(int payload_len)
1.1 deraadt 1278: {
1.35 ! markus 1279: int remote_channel, display_number, sock = 0, newch;
1.25 markus 1280: const char *display;
1281: char buf[1024], *cp, *remote_host;
1282: int remote_len;
1.35 ! markus 1283: struct addrinfo hints, *ai, *aitop;
! 1284: char strport[NI_MAXSERV];
! 1285: int gaierr;
1.25 markus 1286:
1287: /* Get remote channel number. */
1288: remote_channel = packet_get_int();
1289:
1290: /* Get remote originator name. */
1.29 markus 1291: if (have_hostname_in_open) {
1.25 markus 1292: remote_host = packet_get_string(&remote_len);
1.29 markus 1293: remote_len += 4;
1294: } else {
1.25 markus 1295: remote_host = xstrdup("unknown (remote did not supply name)");
1.29 markus 1296: remote_len = 0;
1297: }
1.25 markus 1298:
1299: debug("Received X11 open request.");
1.29 markus 1300: packet_integrity_check(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN);
1.25 markus 1301:
1302: /* Try to open a socket for the local X server. */
1303: display = getenv("DISPLAY");
1304: if (!display) {
1305: error("DISPLAY not set.");
1306: goto fail;
1307: }
1.27 markus 1308: /*
1309: * Now we decode the value of the DISPLAY variable and make a
1310: * connection to the real X server.
1311: */
1312:
1313: /*
1314: * Check if it is a unix domain socket. Unix domain displays are in
1315: * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
1316: */
1.25 markus 1317: if (strncmp(display, "unix:", 5) == 0 ||
1318: display[0] == ':') {
1319: /* Connect to the unix domain socket. */
1320: if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
1321: error("Could not parse display number from DISPLAY: %.100s",
1322: display);
1323: goto fail;
1324: }
1325: /* Create a socket. */
1326: sock = connect_local_xsocket(display_number);
1327: if (sock < 0)
1328: goto fail;
1329:
1330: /* OK, we now have a connection to the display. */
1331: goto success;
1332: }
1.27 markus 1333: /*
1334: * Connect to an inet socket. The DISPLAY value is supposedly
1335: * hostname:d[.s], where hostname may also be numeric IP address.
1336: */
1.25 markus 1337: strncpy(buf, display, sizeof(buf));
1338: buf[sizeof(buf) - 1] = 0;
1339: cp = strchr(buf, ':');
1340: if (!cp) {
1341: error("Could not find ':' in DISPLAY: %.100s", display);
1342: goto fail;
1343: }
1344: *cp = 0;
1.27 markus 1345: /* buf now contains the host name. But first we parse the display number. */
1.25 markus 1346: if (sscanf(cp + 1, "%d", &display_number) != 1) {
1347: error("Could not parse display number from DISPLAY: %.100s",
1348: display);
1349: goto fail;
1350: }
1.35 ! markus 1351:
! 1352: /* Look up the host address */
! 1353: memset(&hints, 0, sizeof(hints));
! 1354: hints.ai_family = IPv4or6;
! 1355: hints.ai_socktype = SOCK_STREAM;
! 1356: snprintf(strport, sizeof strport, "%d", 6000 + display_number);
! 1357: if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
! 1358: error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
1.25 markus 1359: goto fail;
1360: }
1.35 ! markus 1361: for (ai = aitop; ai; ai = ai->ai_next) {
! 1362: /* Create a socket. */
! 1363: sock = socket(ai->ai_family, SOCK_STREAM, 0);
! 1364: if (sock < 0) {
! 1365: debug("socket: %.100s", strerror(errno));
! 1366: continue;
! 1367: }
1.25 markus 1368: /* Connect it to the display. */
1.35 ! markus 1369: if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
! 1370: debug("connect %.100s port %d: %.100s", buf, 6000 + display_number,
! 1371: strerror(errno));
1.25 markus 1372: close(sock);
1.35 ! markus 1373: continue;
! 1374: }
! 1375: /* Success */
! 1376: break;
! 1377:
! 1378: } /* (ai = aitop, ai; ai = ai->ai_next) */
! 1379: freeaddrinfo(aitop);
! 1380: if (!ai) {
! 1381: error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
! 1382: strerror(errno));
1.25 markus 1383: goto fail;
1384: }
1385: success:
1386: /* We have successfully obtained a connection to the real X display. */
1387:
1388: /* Allocate a channel for this connection. */
1389: if (x11_saved_proto == NULL)
1390: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1391: else
1392: newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1393: channels[newch].remote_id = remote_channel;
1394:
1395: /* Send a confirmation to the remote host. */
1396: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1397: packet_put_int(remote_channel);
1398: packet_put_int(newch);
1399: packet_send();
1400:
1401: return;
1402:
1403: fail:
1404: /* Send refusal to the remote host. */
1405: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1406: packet_put_int(remote_channel);
1407: packet_send();
1.1 deraadt 1408: }
1409:
1.27 markus 1410: /*
1411: * Requests forwarding of X11 connections, generates fake authentication
1412: * data, and enables authentication spoofing.
1413: */
1.1 deraadt 1414:
1.25 markus 1415: void
1416: x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1.1 deraadt 1417: {
1.25 markus 1418: unsigned int data_len = (unsigned int) strlen(data) / 2;
1419: unsigned int i, value;
1420: char *new_data;
1421: int screen_number;
1422: const char *cp;
1423: u_int32_t rand = 0;
1424:
1425: cp = getenv("DISPLAY");
1426: if (cp)
1427: cp = strchr(cp, ':');
1428: if (cp)
1429: cp = strchr(cp, '.');
1430: if (cp)
1431: screen_number = atoi(cp + 1);
1432: else
1433: screen_number = 0;
1434:
1435: /* Save protocol name. */
1436: x11_saved_proto = xstrdup(proto);
1437:
1.27 markus 1438: /*
1439: * Extract real authentication data and generate fake data of the
1440: * same length.
1441: */
1.25 markus 1442: x11_saved_data = xmalloc(data_len);
1443: x11_fake_data = xmalloc(data_len);
1444: for (i = 0; i < data_len; i++) {
1445: if (sscanf(data + 2 * i, "%2x", &value) != 1)
1446: fatal("x11_request_forwarding: bad authentication data: %.100s", data);
1447: if (i % 4 == 0)
1448: rand = arc4random();
1449: x11_saved_data[i] = value;
1450: x11_fake_data[i] = rand & 0xff;
1451: rand >>= 8;
1452: }
1453: x11_saved_data_len = data_len;
1454: x11_fake_data_len = data_len;
1455:
1456: /* Convert the fake data into hex. */
1457: new_data = xmalloc(2 * data_len + 1);
1458: for (i = 0; i < data_len; i++)
1459: sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]);
1460:
1461: /* Send the request packet. */
1462: packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
1463: packet_put_string(proto, strlen(proto));
1464: packet_put_string(new_data, strlen(new_data));
1465: packet_put_int(screen_number);
1466: packet_send();
1467: packet_write_wait();
1468: xfree(new_data);
1.1 deraadt 1469: }
1470:
1471: /* Sends a message to the server to request authentication fd forwarding. */
1472:
1.25 markus 1473: void
1474: auth_request_forwarding()
1.1 deraadt 1475: {
1.25 markus 1476: packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
1477: packet_send();
1478: packet_write_wait();
1.1 deraadt 1479: }
1480:
1.27 markus 1481: /*
1482: * Returns the name of the forwarded authentication socket. Returns NULL if
1483: * there is no forwarded authentication socket. The returned value points to
1484: * a static buffer.
1485: */
1.1 deraadt 1486:
1.25 markus 1487: char *
1488: auth_get_socket_name()
1.1 deraadt 1489: {
1.25 markus 1490: return channel_forwarded_auth_socket_name;
1.1 deraadt 1491: }
1492:
1.12 markus 1493: /* removes the agent forwarding socket */
1494:
1.25 markus 1495: void
1496: cleanup_socket(void)
1497: {
1498: remove(channel_forwarded_auth_socket_name);
1499: rmdir(channel_forwarded_auth_socket_dir);
1.12 markus 1500: }
1501:
1.27 markus 1502: /*
1503: * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
1504: * This starts forwarding authentication requests.
1505: */
1.1 deraadt 1506:
1.25 markus 1507: void
1508: auth_input_request_forwarding(struct passwd * pw)
1.1 deraadt 1509: {
1.25 markus 1510: int sock, newch;
1511: struct sockaddr_un sunaddr;
1512:
1513: if (auth_get_socket_name() != NULL)
1514: fatal("Protocol error: authentication forwarding requested twice.");
1515:
1516: /* Temporarily drop privileged uid for mkdir/bind. */
1517: temporarily_use_uid(pw->pw_uid);
1518:
1519: /* Allocate a buffer for the socket name, and format the name. */
1520: channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
1521: channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
1522: strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
1523:
1524: /* Create private directory for socket */
1525: if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
1526: packet_disconnect("mkdtemp: %.100s", strerror(errno));
1527: snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
1528: channel_forwarded_auth_socket_dir, (int) getpid());
1529:
1530: if (atexit(cleanup_socket) < 0) {
1531: int saved = errno;
1532: cleanup_socket();
1533: packet_disconnect("socket: %.100s", strerror(saved));
1534: }
1535: /* Create the socket. */
1536: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1537: if (sock < 0)
1538: packet_disconnect("socket: %.100s", strerror(errno));
1539:
1540: /* Bind it to the name. */
1541: memset(&sunaddr, 0, sizeof(sunaddr));
1542: sunaddr.sun_family = AF_UNIX;
1543: strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
1544: sizeof(sunaddr.sun_path));
1545:
1546: if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
1547: packet_disconnect("bind: %.100s", strerror(errno));
1548:
1549: /* Restore the privileged uid. */
1550: restore_uid();
1551:
1552: /* Start listening on the socket. */
1553: if (listen(sock, 5) < 0)
1554: packet_disconnect("listen: %.100s", strerror(errno));
1555:
1556: /* Allocate a channel for the authentication agent socket. */
1557: newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
1558: xstrdup("auth socket"));
1.32 deraadt 1559: strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
1560: sizeof(channels[newch].path));
1.1 deraadt 1561: }
1562:
1563: /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
1564:
1.25 markus 1565: void
1566: auth_input_open_request()
1.1 deraadt 1567: {
1.25 markus 1568: int remch, sock, newch;
1569: char *dummyname;
1570:
1571: /* Read the remote channel number from the message. */
1572: remch = packet_get_int();
1573:
1.27 markus 1574: /*
1575: * Get a connection to the local authentication agent (this may again
1576: * get forwarded).
1577: */
1.25 markus 1578: sock = ssh_get_authentication_socket();
1579:
1.27 markus 1580: /*
1581: * If we could not connect the agent, send an error message back to
1582: * the server. This should never happen unless the agent dies,
1583: * because authentication forwarding is only enabled if we have an
1584: * agent.
1585: */
1.25 markus 1586: if (sock < 0) {
1587: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1588: packet_put_int(remch);
1589: packet_send();
1590: return;
1591: }
1592: debug("Forwarding authentication connection.");
1.1 deraadt 1593:
1.27 markus 1594: /*
1595: * Dummy host name. This will be freed when the channel is freed; it
1596: * will still be valid in the packet_put_string below since the
1597: * channel cannot yet be freed at that point.
1598: */
1.25 markus 1599: dummyname = xstrdup("authentication agent connection");
1600:
1601: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
1602: channels[newch].remote_id = remch;
1603:
1604: /* Send a confirmation to the remote host. */
1605: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1606: packet_put_int(remch);
1607: packet_put_int(newch);
1608: packet_send();
1.1 deraadt 1609: }
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