5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 * Created: Fri Mar 24 16:35:24 1995 ylo
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.
34 /* Maximum number of fake X11 displays to try. */
35 #define MAX_DISPLAYS 1000
37 /* Max len of agent socket */
38 #define MAX_SOCKET_NAME 100
41 * Pointer to an array containing all allocated channels. The array is
42 * dynamically extended as needed.
44 static Channel *channels = NULL;
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
51 static int channels_alloc = 0;
54 * Maximum file descriptor value used in any of the channels. This is
55 * updated in channel_allocate.
57 static int channel_max_fd_value = 0;
59 /* Name and directory of socket for authentication agent forwarding. */
60 static char *channel_forwarded_auth_socket_name = NULL;
61 static char *channel_forwarded_auth_socket_dir = NULL;
63 /* Saved X11 authentication protocol name. */
64 char *x11_saved_proto = NULL;
66 /* Saved X11 authentication data. This is the real data. */
67 char *x11_saved_data = NULL;
68 unsigned int x11_saved_data_len = 0;
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.
74 char *x11_fake_data = NULL;
75 unsigned int x11_fake_data_len;
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).
84 char *host; /* Host name. */
85 u_short port; /* Port number. */
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;
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.
97 static int all_opens_permitted = 0;
99 /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
100 static int have_hostname_in_open = 0;
102 /* Sets specific protocol options. */
105 channel_set_options(int hostname_in_open)
107 have_hostname_in_open = hostname_in_open;
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.
117 channel_permit_all_opens()
119 all_opens_permitted = 1;
123 * Allocate a new channel object and set its type and socket. This will cause
124 * remote_name to be freed.
128 channel_allocate(int type, int sock, char *remote_name)
133 /* Update the maximum file descriptor value. */
134 if (sock > channel_max_fd_value)
135 channel_max_fd_value = sock;
136 /* XXX set close-on-exec -markus */
138 /* Do initial allocation if this is the first call. */
139 if (channels_alloc == 0) {
141 channels = xmalloc(channels_alloc * sizeof(Channel));
142 for (i = 0; i < channels_alloc; i++)
143 channels[i].type = SSH_CHANNEL_FREE;
145 * Kludge: arrange a call to channel_stop_listening if we
146 * terminate with fatal().
148 fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
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. */
158 /* There are no free slots. Take last+1 slot and expand the array. */
159 found = channels_alloc;
160 channels_alloc += 10;
161 debug("channel: expanding %d", channels_alloc);
162 channels = xrealloc(channels, channels_alloc * sizeof(Channel));
163 for (i = found; i < channels_alloc; i++)
164 channels[i].type = SSH_CHANNEL_FREE;
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);
175 c->remote_name = remote_name;
176 debug("channel %d: new [%s]", found, remote_name);
180 /* Free the channel and close its socket. */
183 channel_free(int channel)
185 if (channel < 0 || channel >= channels_alloc ||
186 channels[channel].type == SSH_CHANNEL_FREE)
187 packet_disconnect("channel free: bad local channel %d", channel);
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;
202 * This is called just before select() to add any bits relevant to channels
203 * in the select bitmasks.
207 channel_prepare_select(fd_set * readset, fd_set * writeset)
212 unsigned int proto_len, data_len;
214 for (i = 0; i < channels_alloc; i++) {
218 case SSH_CHANNEL_X11_LISTENER:
219 case SSH_CHANNEL_PORT_LISTENER:
220 case SSH_CHANNEL_AUTH_SOCKET:
221 FD_SET(ch->sock, readset);
224 case SSH_CHANNEL_OPEN:
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);
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) {
246 case SSH_CHANNEL_INPUT_DRAINING:
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);
253 ch->type = SSH_CHANNEL_CLOSED;
254 debug("Closing channel %d after input drain.", i);
259 case SSH_CHANNEL_OUTPUT_DRAINING:
261 fatal("cannot happen: OUT_DRAIN");
262 if (buffer_len(&ch->output) == 0) {
266 FD_SET(ch->sock, writeset);
269 case SSH_CHANNEL_X11_OPEN:
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
280 /* Check if the fixed size part of the packet is in buffer. */
281 if (buffer_len(&ch->output) < 12)
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];
293 debug("Initial X11 packet contains bad byte order byte: 0x%x",
295 ch->type = SSH_CHANNEL_OPEN;
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))
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;
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;
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;
327 * Received authentication protocol and data match
328 * our fake data. Substitute the fake data with real
331 memcpy(ucp + 12 + ((proto_len + 3) & ~3),
332 x11_saved_data, x11_saved_data_len);
334 /* Start normal processing for the channel. */
335 ch->type = SSH_CHANNEL_OPEN;
340 * We have received an X11 connection that has bad
341 * authentication information.
343 log("X11 connection rejected because of wrong authentication.\r\n");
344 buffer_clear(&ch->input);
345 buffer_clear(&ch->output);
349 ch->type = SSH_CHANNEL_CLOSED;
350 packet_start(SSH_MSG_CHANNEL_CLOSE);
351 packet_put_int(ch->remote_id);
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);
361 case SSH_CHANNEL_FREE:
369 * After select, perform any appropriate operations for channels which have
374 channel_after_select(fd_set * readset, fd_set * writeset)
376 struct sockaddr addr;
377 int addrlen, newsock, i, newch, len;
379 char buf[16384], *remote_hostname;
381 /* Loop over all channels... */
382 for (i = 0; i < channels_alloc; i++) {
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);
392 error("accept: %.100s", strerror(errno));
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,
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));
409 case SSH_CHANNEL_PORT_LISTENER:
411 * This socket is listening for connections to a
412 * forwarded TCP/IP port.
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);
420 error("accept: %.100s", strerror(errno));
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,
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));
440 case SSH_CHANNEL_AUTH_SOCKET:
442 * This is the authentication agent socket listening
443 * for connections from clients.
445 if (FD_ISSET(ch->sock, readset)) {
448 newsock = accept(ch->sock, &addr, &len);
450 error("accept from auth socket: %.100s", strerror(errno));
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);
461 case SSH_CHANNEL_OPEN:
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.
469 * Read available incoming data and append it to
470 * buffer; shutdown socket, if read or write failes
472 if (FD_ISSET(ch->sock, readset)) {
473 len = read(ch->sock, buf, sizeof(buf));
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);
480 chan_read_failed(ch);
484 buffer_append(&ch->input, buf, len);
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));
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;
496 chan_write_failed(ch);
500 buffer_consume(&ch->output, len);
504 case SSH_CHANNEL_OUTPUT_DRAINING:
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));
512 buffer_consume(&ch->output, buffer_len(&ch->output));
514 buffer_consume(&ch->output, len);
518 case SSH_CHANNEL_X11_OPEN:
519 case SSH_CHANNEL_FREE:
526 /* If there is data to send to the connection, send some of it now. */
529 channel_output_poll()
534 for (i = 0; i < channels_alloc; i++) {
536 /* We are only interested in channels that can have buffered incoming data. */
537 if (ch->type != SSH_CHANNEL_OPEN &&
538 ch->type != SSH_CHANNEL_INPUT_DRAINING)
541 /* Get the amount of buffered data for this channel. */
542 len = buffer_len(&ch->input);
544 /* Send some data for the other side over the secure connection. */
545 if (packet_is_interactive()) {
549 /* Keep the packets at reasonable size. */
553 packet_start(SSH_MSG_CHANNEL_DATA);
554 packet_put_int(ch->remote_id);
555 packet_put_string(buffer_ptr(&ch->input), len);
557 buffer_consume(&ch->input, len);
558 } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) {
560 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
562 * input-buffer is empty and read-socket shutdown:
563 * tell peer, that we will not send more data: send IEOF
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
577 channel_input_data(int payload_len)
581 unsigned int data_len;
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);
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)
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);
602 * Returns true if no channel has too much buffered data, and false if one or
603 * more channel is overfull.
607 channel_not_very_much_buffered_data()
612 for (i = 0; i < channels_alloc; i++) {
615 case SSH_CHANNEL_X11_LISTENER:
616 case SSH_CHANNEL_PORT_LISTENER:
617 case SSH_CHANNEL_AUTH_SOCKET:
619 case SSH_CHANNEL_OPEN:
620 if (buffer_len(&ch->input) > packet_get_maxsize())
622 if (buffer_len(&ch->output) > packet_get_maxsize())
625 case SSH_CHANNEL_INPUT_DRAINING:
626 case SSH_CHANNEL_OUTPUT_DRAINING:
627 case SSH_CHANNEL_X11_OPEN:
628 case SSH_CHANNEL_FREE:
636 /* This is called after receiving CHANNEL_CLOSE/IEOF. */
639 channel_input_close()
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);
650 /* proto version 1.5 overloads CLOSE with IEOF */
651 chan_rcvd_ieof(&channels[channel]);
656 * Send a confirmation that we have closed the channel and no more
657 * data is coming for it.
659 packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
660 packet_put_int(channels[channel].remote_id);
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.
670 if (channels[channel].type != SSH_CHANNEL_CLOSED) {
672 * Not a closed channel - mark it as draining, which will
673 * cause it to be freed later.
675 buffer_consume(&channels[channel].input,
676 buffer_len(&channels[channel].input));
677 channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING;
681 /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */
684 channel_input_close_confirmation()
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.",
695 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
696 chan_rcvd_oclose(&channels[channel]);
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);
703 /* Free the channel. */
704 channel_free(channel);
707 /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
710 channel_input_open_confirmation()
712 int channel, remote_channel;
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.",
721 /* Get remote side's id for this channel. */
722 remote_channel = packet_get_int();
724 /* Record the remote channel number and mark that the channel is now open. */
725 channels[channel].remote_id = remote_channel;
726 channels[channel].type = SSH_CHANNEL_OPEN;
729 /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
732 channel_input_open_failure()
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.",
743 /* Free the channel. This will also close the socket. */
744 channel_free(channel);
748 * Stops listening for channels, and removes any unix domain sockets that we
753 channel_stop_listening()
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);
763 case SSH_CHANNEL_PORT_LISTENER:
764 case SSH_CHANNEL_X11_LISTENER:
765 close(channels[i].sock);
775 * Closes the sockets of all channels. This is used to close extra file
776 * descriptors after a fork.
783 for (i = 0; i < channels_alloc; i++) {
784 if (channels[i].type != SSH_CHANNEL_FREE)
785 close(channels[i].sock);
789 /* Returns the maximum file descriptor number used by the channels. */
794 return channel_max_fd_value;
797 /* Returns true if any channel is still open. */
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:
811 case SSH_CHANNEL_OPENING:
812 case SSH_CHANNEL_OPEN:
813 case SSH_CHANNEL_X11_OPEN:
815 case SSH_CHANNEL_INPUT_DRAINING:
816 case SSH_CHANNEL_OUTPUT_DRAINING:
818 fatal("cannot happen: OUT_DRAIN");
821 fatal("channel_still_open: bad channel type %d", channels[i].type);
828 * Returns a message describing the currently open forwarded connections,
829 * suitable for sending to the client. The message contains crlf pairs for
834 channel_open_message()
840 buffer_init(&buffer);
841 snprintf(buf, sizeof buf, "The following connections are open:\r\n");
842 buffer_append(&buffer, buf, strlen(buf));
843 for (i = 0; i < channels_alloc; i++) {
844 Channel *c = &channels[i];
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:
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));
863 fatal("channel_still_open: bad channel type %d", c->type);
867 buffer_append(&buffer, "\0", 1);
868 cp = xstrdup(buffer_ptr(&buffer));
869 buffer_free(&buffer);
874 * Initiate forwarding of connections to local port "port" through the secure
875 * channel to host:port from remote side.
879 channel_request_local_forwarding(u_short port, const char *host,
880 u_short host_port, int gateway_ports)
882 int ch, sock, on = 1;
883 struct sockaddr_in sin;
884 struct linger linger;
886 if (strlen(host) > sizeof(channels[0].path) - 1)
887 packet_disconnect("Forward host name too long.");
889 /* Create a port to listen for the host. */
890 sock = socket(AF_INET, SOCK_STREAM, 0);
892 packet_disconnect("socket: %.100s", strerror(errno));
894 /* Initialize socket address. */
895 memset(&sin, 0, sizeof(sin));
896 sin.sin_family = AF_INET;
897 if (gateway_ports == 1)
898 sin.sin_addr.s_addr = htonl(INADDR_ANY);
900 sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
901 sin.sin_port = htons(port);
904 * Set socket options. We would like the socket to disappear as soon
905 * as it has been closed for whatever reason.
907 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
910 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
912 /* Bind the socket to the address. */
913 if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0)
914 packet_disconnect("bind: %.100s", strerror(errno));
916 /* Start listening for connections on the socket. */
917 if (listen(sock, 5) < 0)
918 packet_disconnect("listen: %.100s", strerror(errno));
920 /* Allocate a channel number for the socket. */
921 ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
922 xstrdup("port listener"));
923 strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
924 channels[ch].host_port = host_port;
925 channels[ch].listening_port = port;
929 * Initiate forwarding of connections to port "port" on remote host through
930 * the secure channel to host:port from local side.
934 channel_request_remote_forwarding(u_short port, const char *host,
938 /* Record locally that connection to this host/port is permitted. */
939 if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
940 fatal("channel_request_remote_forwarding: too many forwards");
942 permitted_opens[num_permitted_opens].host = xstrdup(host);
943 permitted_opens[num_permitted_opens].port = remote_port;
944 num_permitted_opens++;
946 /* Send the forward request to the remote side. */
947 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
948 packet_put_int(port);
949 packet_put_string(host, strlen(host));
950 packet_put_int(remote_port);
955 * Wait for response from the remote side. It will send a disconnect
956 * message on failure, and we will never see it here.
958 packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
962 * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
963 * listening for the port, and sends back a success reply (or disconnect
964 * message if there was an error). This never returns if there was an error.
968 channel_input_port_forward_request(int is_root)
970 u_short port, host_port;
973 /* Get arguments from the packet. */
974 port = packet_get_int();
975 hostname = packet_get_string(NULL);
976 host_port = packet_get_int();
979 * Check that an unprivileged user is not trying to forward a
982 if (port < IPPORT_RESERVED && !is_root)
983 packet_disconnect("Requested forwarding of port %d but user is not root.",
986 * Initiate forwarding,
987 * bind port to localhost only (gateway ports == 0).
989 channel_request_local_forwarding(port, hostname, host_port, 0);
991 /* Free the argument string. */
996 * This is called after receiving PORT_OPEN message. This attempts to
997 * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
998 * or CHANNEL_OPEN_FAILURE.
1002 channel_input_port_open(int payload_len)
1004 int remote_channel, sock, newch, i;
1006 struct sockaddr_in sin;
1007 char *host, *originator_string;
1009 int host_len, originator_len;
1011 /* Get remote channel number. */
1012 remote_channel = packet_get_int();
1014 /* Get host name to connect to. */
1015 host = packet_get_string(&host_len);
1017 /* Get port to connect to. */
1018 host_port = packet_get_int();
1020 /* Get remote originator name. */
1021 if (have_hostname_in_open) {
1022 originator_string = packet_get_string(&originator_len);
1023 originator_len += 4; /* size of packet_int */
1025 originator_string = xstrdup("unknown (remote did not supply name)");
1026 originator_len = 0; /* no originator supplied */
1029 packet_integrity_check(payload_len,
1030 4 + 4 + host_len + 4 + originator_len,
1033 /* Check if opening that port is permitted. */
1034 if (!all_opens_permitted) {
1035 /* Go trough all permitted ports. */
1036 for (i = 0; i < num_permitted_opens; i++)
1037 if (permitted_opens[i].port == host_port &&
1038 strcmp(permitted_opens[i].host, host) == 0)
1041 /* Check if we found the requested port among those permitted. */
1042 if (i >= num_permitted_opens) {
1043 /* The port is not permitted. */
1044 log("Received request to connect to %.100s:%d, but the request was denied.",
1046 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1047 packet_put_int(remote_channel);
1051 memset(&sin, 0, sizeof(sin));
1052 sin.sin_addr.s_addr = inet_addr(host);
1053 if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) {
1054 /* It was a valid numeric host address. */
1055 sin.sin_family = AF_INET;
1057 /* Look up the host address from the name servers. */
1058 hp = gethostbyname(host);
1060 error("%.100s: unknown host.", host);
1063 if (!hp->h_addr_list[0]) {
1064 error("%.100s: host has no IP address.", host);
1067 sin.sin_family = hp->h_addrtype;
1068 memcpy(&sin.sin_addr, hp->h_addr_list[0],
1069 sizeof(sin.sin_addr));
1071 sin.sin_port = htons(host_port);
1073 /* Create the socket. */
1074 sock = socket(sin.sin_family, SOCK_STREAM, 0);
1076 error("socket: %.100s", strerror(errno));
1079 /* Connect to the host/port. */
1080 if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1081 error("connect %.100s:%d: %.100s", host, host_port,
1086 /* Successful connection. */
1088 /* Allocate a channel for this connection. */
1089 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1090 channels[newch].remote_id = remote_channel;
1092 /* Send a confirmation to the remote host. */
1093 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1094 packet_put_int(remote_channel);
1095 packet_put_int(newch);
1098 /* Free the argument string. */
1104 /* Free the argument string. */
1107 /* Send refusal to the remote host. */
1108 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1109 packet_put_int(remote_channel);
1114 * Creates an internet domain socket for listening for X11 connections.
1115 * Returns a suitable value for the DISPLAY variable, or NULL if an error
1120 x11_create_display_inet(int screen_number, int x11_display_offset)
1122 int display_number, sock;
1124 struct sockaddr_in sin;
1126 char hostname[MAXHOSTNAMELEN];
1128 for (display_number = x11_display_offset;
1129 display_number < MAX_DISPLAYS;
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);
1137 sock = socket(AF_INET, SOCK_STREAM, 0);
1139 error("socket: %.100s", strerror(errno));
1142 if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1143 debug("bind port %d: %.100s", port, strerror(errno));
1144 shutdown(sock, SHUT_RDWR);
1150 if (display_number >= MAX_DISPLAYS) {
1151 error("Failed to allocate internet-domain X11 display socket.");
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);
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);
1167 /* Allocate a channel for the socket. */
1168 (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
1169 xstrdup("X11 inet listener"));
1171 /* Return a suitable value for the DISPLAY environment variable. */
1172 return xstrdup(buf);
1176 #define X_UNIX_PATH "/tmp/.X11-unix/X"
1181 connect_local_xsocket(unsigned int dnr)
1183 static const char *const x_sockets[] = {
1185 "/var/X/.X11-unix/X" "%u",
1186 "/usr/spool/sockets/X11/" "%u",
1190 struct sockaddr_un addr;
1191 const char *const * path;
1193 for (path = x_sockets; *path; ++path) {
1194 sock = socket(AF_UNIX, SOCK_STREAM, 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)
1204 error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
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.
1216 x11_input_open(int payload_len)
1218 int remote_channel, display_number, sock, newch;
1219 const char *display;
1220 struct sockaddr_in sin;
1221 char buf[1024], *cp, *remote_host;
1225 /* Get remote channel number. */
1226 remote_channel = packet_get_int();
1228 /* Get remote originator name. */
1229 if (have_hostname_in_open) {
1230 remote_host = packet_get_string(&remote_len);
1233 remote_host = xstrdup("unknown (remote did not supply name)");
1237 debug("Received X11 open request.");
1238 packet_integrity_check(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN);
1240 /* Try to open a socket for the local X server. */
1241 display = getenv("DISPLAY");
1243 error("DISPLAY not set.");
1247 * Now we decode the value of the DISPLAY variable and make a
1248 * connection to the real X server.
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]
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",
1263 /* Create a socket. */
1264 sock = connect_local_xsocket(display_number);
1268 /* OK, we now have a connection to the display. */
1272 * Connect to an inet socket. The DISPLAY value is supposedly
1273 * hostname:d[.s], where hostname may also be numeric IP address.
1275 strncpy(buf, display, sizeof(buf));
1276 buf[sizeof(buf) - 1] = 0;
1277 cp = strchr(buf, ':');
1279 error("Could not find ':' in DISPLAY: %.100s", display);
1283 /* buf now contains the host name. But first we parse the display number. */
1284 if (sscanf(cp + 1, "%d", &display_number) != 1) {
1285 error("Could not parse display number from DISPLAY: %.100s",
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;
1296 /* Not a numeric IP address. */
1297 /* Look up the host address from the name servers. */
1298 hp = gethostbyname(buf);
1300 error("%.100s: unknown host.", buf);
1303 if (!hp->h_addr_list[0]) {
1304 error("%.100s: host has no IP address.", buf);
1307 sin.sin_family = hp->h_addrtype;
1308 memcpy(&sin.sin_addr, hp->h_addr_list[0],
1309 sizeof(sin.sin_addr));
1311 /* Set port number. */
1312 sin.sin_port = htons(6000 + display_number);
1314 /* Create a socket. */
1315 sock = socket(sin.sin_family, SOCK_STREAM, 0);
1317 error("socket: %.100s", strerror(errno));
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,
1328 /* We have successfully obtained a connection to the real X display. */
1330 /* Allocate a channel for this connection. */
1331 if (x11_saved_proto == NULL)
1332 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1334 newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1335 channels[newch].remote_id = remote_channel;
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);
1346 /* Send refusal to the remote host. */
1347 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1348 packet_put_int(remote_channel);
1353 * Requests forwarding of X11 connections, generates fake authentication
1354 * data, and enables authentication spoofing.
1358 x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1360 unsigned int data_len = (unsigned int) strlen(data) / 2;
1361 unsigned int i, value;
1367 cp = getenv("DISPLAY");
1369 cp = strchr(cp, ':');
1371 cp = strchr(cp, '.');
1373 screen_number = atoi(cp + 1);
1377 /* Save protocol name. */
1378 x11_saved_proto = xstrdup(proto);
1381 * Extract real authentication data and generate fake data of the
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);
1390 rand = arc4random();
1391 x11_saved_data[i] = value;
1392 x11_fake_data[i] = rand & 0xff;
1395 x11_saved_data_len = data_len;
1396 x11_fake_data_len = data_len;
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]);
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);
1409 packet_write_wait();
1413 /* Sends a message to the server to request authentication fd forwarding. */
1416 auth_request_forwarding()
1418 packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
1420 packet_write_wait();
1424 * Returns the name of the forwarded authentication socket. Returns NULL if
1425 * there is no forwarded authentication socket. The returned value points to
1430 auth_get_socket_name()
1432 return channel_forwarded_auth_socket_name;
1435 /* removes the agent forwarding socket */
1438 cleanup_socket(void)
1440 remove(channel_forwarded_auth_socket_name);
1441 rmdir(channel_forwarded_auth_socket_dir);
1445 * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
1446 * This starts forwarding authentication requests.
1450 auth_input_request_forwarding(struct passwd * pw)
1453 struct sockaddr_un sunaddr;
1455 if (auth_get_socket_name() != NULL)
1456 fatal("Protocol error: authentication forwarding requested twice.");
1458 /* Temporarily drop privileged uid for mkdir/bind. */
1459 temporarily_use_uid(pw->pw_uid);
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);
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());
1472 if (atexit(cleanup_socket) < 0) {
1475 packet_disconnect("socket: %.100s", strerror(saved));
1477 /* Create the socket. */
1478 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1480 packet_disconnect("socket: %.100s", strerror(errno));
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));
1488 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
1489 packet_disconnect("bind: %.100s", strerror(errno));
1491 /* Restore the privileged uid. */
1494 /* Start listening on the socket. */
1495 if (listen(sock, 5) < 0)
1496 packet_disconnect("listen: %.100s", strerror(errno));
1498 /* Allocate a channel for the authentication agent socket. */
1499 newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
1500 xstrdup("auth socket"));
1501 strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
1502 sizeof(channels[newch].path));
1505 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
1508 auth_input_open_request()
1510 int remch, sock, newch;
1513 /* Read the remote channel number from the message. */
1514 remch = packet_get_int();
1517 * Get a connection to the local authentication agent (this may again
1520 sock = ssh_get_authentication_socket();
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
1529 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1530 packet_put_int(remch);
1534 debug("Forwarding authentication connection.");
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.
1541 dummyname = xstrdup("authentication agent connection");
1543 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
1544 channels[newch].remote_id = remch;
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);