Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
| 2 | |
| 3 | channels.c |
| 4 | |
| 5 | Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | |
| 7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | All rights reserved |
| 9 | |
| 10 | Created: Fri Mar 24 16:35:24 1995 ylo |
| 11 | |
| 12 | This file contains functions for generic socket connection forwarding. |
| 13 | There is also code for initiating connection forwarding for X11 connections, |
| 14 | arbitrary tcp/ip connections, and the authentication agent connection. |
| 15 | |
| 16 | */ |
| 17 | |
| 18 | #include "includes.h" |
Damien Miller | fd7c911 | 1999-11-08 16:15:55 +1100 | [diff] [blame] | 19 | RCSID("$Id: channels.c,v 1.4 1999/11/08 05:15:55 damien Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 20 | |
| 21 | #include "ssh.h" |
| 22 | #include "packet.h" |
| 23 | #include "xmalloc.h" |
| 24 | #include "buffer.h" |
| 25 | #include "authfd.h" |
| 26 | #include "uidswap.h" |
| 27 | #include "servconf.h" |
| 28 | |
| 29 | #include "channels.h" |
| 30 | #include "nchan.h" |
| 31 | #include "compat.h" |
| 32 | |
| 33 | /* Maximum number of fake X11 displays to try. */ |
| 34 | #define MAX_DISPLAYS 1000 |
| 35 | |
| 36 | /* Max len of agent socket */ |
| 37 | #define MAX_SOCKET_NAME 100 |
| 38 | |
| 39 | /* Pointer to an array containing all allocated channels. The array is |
| 40 | dynamically extended as needed. */ |
| 41 | static Channel *channels = NULL; |
| 42 | |
| 43 | /* Size of the channel array. All slots of the array must always be |
| 44 | initialized (at least the type field); unused slots are marked with |
| 45 | type SSH_CHANNEL_FREE. */ |
| 46 | static int channels_alloc = 0; |
| 47 | |
| 48 | /* Maximum file descriptor value used in any of the channels. This is updated |
| 49 | in channel_allocate. */ |
| 50 | static int channel_max_fd_value = 0; |
| 51 | |
| 52 | /* Name and directory of socket for authentication agent forwarding. */ |
| 53 | static char *channel_forwarded_auth_socket_name = NULL; |
| 54 | static char *channel_forwarded_auth_socket_dir = NULL; |
| 55 | |
| 56 | /* Saved X11 authentication protocol name. */ |
| 57 | char *x11_saved_proto = NULL; |
| 58 | |
| 59 | /* Saved X11 authentication data. This is the real data. */ |
| 60 | char *x11_saved_data = NULL; |
| 61 | unsigned int x11_saved_data_len = 0; |
| 62 | |
| 63 | /* Fake X11 authentication data. This is what the server will be sending |
| 64 | us; we should replace any occurrences of this by the real data. */ |
| 65 | char *x11_fake_data = NULL; |
| 66 | unsigned int x11_fake_data_len; |
| 67 | |
| 68 | /* Data structure for storing which hosts are permitted for forward requests. |
| 69 | The local sides of any remote forwards are stored in this array to prevent |
| 70 | a corrupt remote server from accessing arbitrary TCP/IP ports on our |
| 71 | local network (which might be behind a firewall). */ |
| 72 | typedef struct |
| 73 | { |
| 74 | char *host; /* Host name. */ |
| 75 | int port; /* Port number. */ |
| 76 | } ForwardPermission; |
| 77 | |
| 78 | /* List of all permitted host/port pairs to connect. */ |
| 79 | static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION]; |
| 80 | /* Number of permitted host/port pairs in the array. */ |
| 81 | static int num_permitted_opens = 0; |
| 82 | /* If this is true, all opens are permitted. This is the case on the |
| 83 | server on which we have to trust the client anyway, and the user could |
| 84 | do anything after logging in anyway. */ |
| 85 | static int all_opens_permitted = 0; |
| 86 | |
| 87 | /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */ |
| 88 | static int have_hostname_in_open = 0; |
| 89 | |
| 90 | /* Sets specific protocol options. */ |
| 91 | |
| 92 | void channel_set_options(int hostname_in_open) |
| 93 | { |
| 94 | have_hostname_in_open = hostname_in_open; |
| 95 | } |
| 96 | |
| 97 | /* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually |
| 98 | called by the server, because the user could connect to any port anyway, |
| 99 | and the server has no way to know but to trust the client anyway. */ |
| 100 | |
| 101 | void channel_permit_all_opens() |
| 102 | { |
| 103 | all_opens_permitted = 1; |
| 104 | } |
| 105 | |
| 106 | /* Allocate a new channel object and set its type and socket. |
| 107 | This will cause remote_name to be freed. */ |
| 108 | |
| 109 | int channel_allocate(int type, int sock, char *remote_name) |
| 110 | { |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 111 | int i, found; |
| 112 | Channel *c; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 113 | |
| 114 | /* Update the maximum file descriptor value. */ |
| 115 | if (sock > channel_max_fd_value) |
| 116 | channel_max_fd_value = sock; |
| 117 | |
| 118 | /* Do initial allocation if this is the first call. */ |
| 119 | if (channels_alloc == 0) |
| 120 | { |
| 121 | channels_alloc = 10; |
| 122 | channels = xmalloc(channels_alloc * sizeof(Channel)); |
| 123 | for (i = 0; i < channels_alloc; i++) |
| 124 | channels[i].type = SSH_CHANNEL_FREE; |
| 125 | |
| 126 | /* Kludge: arrange a call to channel_stop_listening if we terminate |
| 127 | with fatal(). */ |
| 128 | fatal_add_cleanup((void (*)(void *))channel_stop_listening, NULL); |
| 129 | } |
| 130 | |
| 131 | /* Try to find a free slot where to put the new channel. */ |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 132 | for (found = -1, i = 0; i < channels_alloc; i++) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 133 | if (channels[i].type == SSH_CHANNEL_FREE) |
| 134 | { |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 135 | /* Found a free slot. */ |
| 136 | found = i; |
| 137 | break; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 138 | } |
| 139 | |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 140 | if (found == -1) |
| 141 | { |
| 142 | /* There are no free slots. Take last+1 slot and expand the array. */ |
| 143 | found = channels_alloc; |
| 144 | channels_alloc += 10; |
| 145 | debug("channel: expanding %d", channels_alloc); |
| 146 | channels = xrealloc(channels, channels_alloc * sizeof(Channel)); |
| 147 | for (i = found; i < channels_alloc; i++) |
| 148 | channels[i].type = SSH_CHANNEL_FREE; |
| 149 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 150 | |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 151 | /* Initialize and return new channel number. */ |
| 152 | c=&channels[found]; |
| 153 | buffer_init(&c->input); |
| 154 | buffer_init(&c->output); |
| 155 | chan_init_iostates(c); |
| 156 | c->self = found; |
| 157 | c->type = type; |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 158 | c->sock = sock; |
| 159 | c->remote_id = -1; |
| 160 | c->remote_name = remote_name; |
| 161 | debug("channel %d: new [%s]", found, remote_name); |
| 162 | return found; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 163 | } |
| 164 | |
| 165 | /* Free the channel and close its socket. */ |
| 166 | |
| 167 | void channel_free(int channel) |
| 168 | { |
Damien Miller | fd7c911 | 1999-11-08 16:15:55 +1100 | [diff] [blame] | 169 | if (channel < 0 || channel >= channels_alloc || |
| 170 | channels[channel].type == SSH_CHANNEL_FREE) |
| 171 | packet_disconnect("channel free: bad local channel %d", channel); |
| 172 | |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 173 | if(compat13) |
| 174 | shutdown(channels[channel].sock, SHUT_RDWR); |
| 175 | close(channels[channel].sock); |
| 176 | buffer_free(&channels[channel].input); |
| 177 | buffer_free(&channels[channel].output); |
| 178 | channels[channel].type = SSH_CHANNEL_FREE; |
| 179 | if (channels[channel].remote_name) |
| 180 | { |
| 181 | xfree(channels[channel].remote_name); |
| 182 | channels[channel].remote_name = NULL; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | /* This is called just before select() to add any bits relevant to |
| 187 | channels in the select bitmasks. */ |
| 188 | |
| 189 | void channel_prepare_select(fd_set *readset, fd_set *writeset) |
| 190 | { |
| 191 | int i; |
| 192 | Channel *ch; |
| 193 | unsigned char *ucp; |
| 194 | unsigned int proto_len, data_len; |
| 195 | |
| 196 | for (i = 0; i < channels_alloc; i++) |
| 197 | { |
| 198 | ch = &channels[i]; |
| 199 | redo: |
| 200 | switch (ch->type) |
| 201 | { |
| 202 | case SSH_CHANNEL_X11_LISTENER: |
| 203 | case SSH_CHANNEL_PORT_LISTENER: |
| 204 | case SSH_CHANNEL_AUTH_SOCKET: |
| 205 | FD_SET(ch->sock, readset); |
| 206 | break; |
| 207 | |
| 208 | case SSH_CHANNEL_OPEN: |
| 209 | if(compat13){ |
| 210 | if (buffer_len(&ch->input) < 32768) |
| 211 | FD_SET(ch->sock, readset); |
| 212 | if (buffer_len(&ch->output) > 0) |
| 213 | FD_SET(ch->sock, writeset); |
| 214 | break; |
| 215 | } |
| 216 | /* test whether sockets are 'alive' for read/write */ |
| 217 | if (ch->istate == CHAN_INPUT_OPEN) |
| 218 | if (buffer_len(&ch->input) < 32768) |
| 219 | FD_SET(ch->sock, readset); |
| 220 | if (ch->ostate == CHAN_OUTPUT_OPEN || ch->ostate == CHAN_OUTPUT_WAIT_DRAIN){ |
| 221 | if (buffer_len(&ch->output) > 0){ |
| 222 | FD_SET(ch->sock, writeset); |
| 223 | }else if(ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { |
| 224 | chan_obuf_empty(ch); |
| 225 | } |
| 226 | } |
| 227 | break; |
| 228 | |
| 229 | case SSH_CHANNEL_INPUT_DRAINING: |
| 230 | if (!compat13) |
| 231 | fatal("cannot happen: IN_DRAIN"); |
| 232 | if (buffer_len(&ch->input) == 0) |
| 233 | { |
| 234 | packet_start(SSH_MSG_CHANNEL_CLOSE); |
| 235 | packet_put_int(ch->remote_id); |
| 236 | packet_send(); |
| 237 | ch->type = SSH_CHANNEL_CLOSED; |
| 238 | debug("Closing channel %d after input drain.", i); |
| 239 | break; |
| 240 | } |
| 241 | break; |
| 242 | |
| 243 | case SSH_CHANNEL_OUTPUT_DRAINING: |
| 244 | if (!compat13) |
| 245 | fatal("cannot happen: OUT_DRAIN"); |
| 246 | if (buffer_len(&ch->output) == 0) |
| 247 | { |
| 248 | /* debug("Freeing channel %d after output drain.", i); */ |
| 249 | channel_free(i); |
| 250 | break; |
| 251 | } |
| 252 | FD_SET(ch->sock, writeset); |
| 253 | break; |
| 254 | |
| 255 | case SSH_CHANNEL_X11_OPEN: |
| 256 | /* This is a special state for X11 authentication spoofing. An |
| 257 | opened X11 connection (when authentication spoofing is being |
| 258 | done) remains in this state until the first packet has been |
| 259 | completely read. The authentication data in that packet is |
| 260 | then substituted by the real data if it matches the fake data, |
| 261 | and the channel is put into normal mode. */ |
| 262 | |
| 263 | /* Check if the fixed size part of the packet is in buffer. */ |
| 264 | if (buffer_len(&ch->output) < 12) |
| 265 | break; |
| 266 | |
| 267 | /* Parse the lengths of variable-length fields. */ |
| 268 | ucp = (unsigned char *)buffer_ptr(&ch->output); |
| 269 | if (ucp[0] == 0x42) |
| 270 | { /* Byte order MSB first. */ |
| 271 | proto_len = 256 * ucp[6] + ucp[7]; |
| 272 | data_len = 256 * ucp[8] + ucp[9]; |
| 273 | } |
| 274 | else |
| 275 | if (ucp[0] == 0x6c) |
| 276 | { /* Byte order LSB first. */ |
| 277 | proto_len = ucp[6] + 256 * ucp[7]; |
| 278 | data_len = ucp[8] + 256 * ucp[9]; |
| 279 | } |
| 280 | else |
| 281 | { |
| 282 | debug("Initial X11 packet contains bad byte order byte: 0x%x", |
| 283 | ucp[0]); |
| 284 | ch->type = SSH_CHANNEL_OPEN; |
| 285 | goto reject; |
| 286 | } |
| 287 | |
| 288 | /* Check if the whole packet is in buffer. */ |
| 289 | if (buffer_len(&ch->output) < |
| 290 | 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) |
| 291 | break; |
| 292 | |
| 293 | /* Check if authentication protocol matches. */ |
| 294 | if (proto_len != strlen(x11_saved_proto) || |
| 295 | memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) |
| 296 | { |
| 297 | debug("X11 connection uses different authentication protocol."); |
| 298 | ch->type = SSH_CHANNEL_OPEN; |
| 299 | goto reject; |
| 300 | } |
| 301 | |
| 302 | /* Check if authentication data matches our fake data. */ |
| 303 | if (data_len != x11_fake_data_len || |
| 304 | memcmp(ucp + 12 + ((proto_len + 3) & ~3), |
| 305 | x11_fake_data, x11_fake_data_len) != 0) |
| 306 | { |
| 307 | debug("X11 auth data does not match fake data."); |
| 308 | ch->type = SSH_CHANNEL_OPEN; |
| 309 | goto reject; |
| 310 | } |
| 311 | |
Damien Miller | fd7c911 | 1999-11-08 16:15:55 +1100 | [diff] [blame] | 312 | /* Check fake data length */ |
| 313 | if (x11_fake_data_len != x11_saved_data_len) |
| 314 | { |
| 315 | error("X11 fake_data_len %d != saved_data_len %d", |
| 316 | x11_fake_data_len, x11_saved_data_len); |
| 317 | ch->type = SSH_CHANNEL_OPEN; |
| 318 | goto reject; |
| 319 | } |
| 320 | |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 321 | /* Received authentication protocol and data match our fake data. |
| 322 | Substitute the fake data with real data. */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 323 | memcpy(ucp + 12 + ((proto_len + 3) & ~3), |
| 324 | x11_saved_data, x11_saved_data_len); |
| 325 | |
| 326 | /* Start normal processing for the channel. */ |
| 327 | ch->type = SSH_CHANNEL_OPEN; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 328 | goto redo; |
| 329 | |
| 330 | reject: |
| 331 | /* We have received an X11 connection that has bad authentication |
| 332 | information. */ |
| 333 | log("X11 connection rejected because of wrong authentication.\r\n"); |
| 334 | buffer_clear(&ch->input); |
| 335 | buffer_clear(&ch->output); |
| 336 | if (compat13) { |
| 337 | close(ch->sock); |
| 338 | ch->sock = -1; |
| 339 | ch->type = SSH_CHANNEL_CLOSED; |
| 340 | packet_start(SSH_MSG_CHANNEL_CLOSE); |
| 341 | packet_put_int(ch->remote_id); |
| 342 | packet_send(); |
| 343 | }else{ |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 344 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 345 | chan_read_failed(ch); |
| 346 | chan_write_failed(ch); |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 347 | debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 348 | } |
| 349 | break; |
| 350 | |
| 351 | case SSH_CHANNEL_FREE: |
| 352 | default: |
| 353 | continue; |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | /* After select, perform any appropriate operations for channels which |
| 359 | have events pending. */ |
| 360 | |
| 361 | void channel_after_select(fd_set *readset, fd_set *writeset) |
| 362 | { |
| 363 | struct sockaddr addr; |
| 364 | int addrlen, newsock, i, newch, len; |
| 365 | Channel *ch; |
| 366 | char buf[16384], *remote_hostname; |
| 367 | |
| 368 | /* Loop over all channels... */ |
| 369 | for (i = 0; i < channels_alloc; i++) |
| 370 | { |
| 371 | ch = &channels[i]; |
| 372 | switch (ch->type) |
| 373 | { |
| 374 | case SSH_CHANNEL_X11_LISTENER: |
| 375 | /* This is our fake X11 server socket. */ |
| 376 | if (FD_ISSET(ch->sock, readset)) |
| 377 | { |
| 378 | debug("X11 connection requested."); |
| 379 | addrlen = sizeof(addr); |
| 380 | newsock = accept(ch->sock, &addr, &addrlen); |
| 381 | if (newsock < 0) |
| 382 | { |
| 383 | error("accept: %.100s", strerror(errno)); |
| 384 | break; |
| 385 | } |
| 386 | remote_hostname = get_remote_hostname(newsock); |
| 387 | snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", |
| 388 | remote_hostname, get_peer_port(newsock)); |
| 389 | xfree(remote_hostname); |
| 390 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| 391 | xstrdup(buf)); |
| 392 | packet_start(SSH_SMSG_X11_OPEN); |
| 393 | packet_put_int(newch); |
| 394 | if (have_hostname_in_open) |
| 395 | packet_put_string(buf, strlen(buf)); |
| 396 | packet_send(); |
| 397 | } |
| 398 | break; |
| 399 | |
| 400 | case SSH_CHANNEL_PORT_LISTENER: |
| 401 | /* This socket is listening for connections to a forwarded TCP/IP |
| 402 | port. */ |
| 403 | if (FD_ISSET(ch->sock, readset)) |
| 404 | { |
| 405 | debug("Connection to port %d forwarding to %.100s:%d requested.", |
| 406 | ch->listening_port, ch->path, ch->host_port); |
| 407 | addrlen = sizeof(addr); |
| 408 | newsock = accept(ch->sock, &addr, &addrlen); |
| 409 | if (newsock < 0) |
| 410 | { |
| 411 | error("accept: %.100s", strerror(errno)); |
| 412 | break; |
| 413 | } |
| 414 | remote_hostname = get_remote_hostname(newsock); |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 415 | snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d", |
| 416 | ch->listening_port, ch->path, ch->host_port, |
| 417 | remote_hostname, get_peer_port(newsock)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 418 | xfree(remote_hostname); |
| 419 | newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| 420 | xstrdup(buf)); |
| 421 | packet_start(SSH_MSG_PORT_OPEN); |
| 422 | packet_put_int(newch); |
| 423 | packet_put_string(ch->path, strlen(ch->path)); |
| 424 | packet_put_int(ch->host_port); |
| 425 | if (have_hostname_in_open) |
| 426 | packet_put_string(buf, strlen(buf)); |
| 427 | packet_send(); |
| 428 | } |
| 429 | break; |
| 430 | |
| 431 | case SSH_CHANNEL_AUTH_SOCKET: |
| 432 | /* This is the authentication agent socket listening for connections |
| 433 | from clients. */ |
| 434 | if (FD_ISSET(ch->sock, readset)) |
| 435 | { |
| 436 | int nchan; |
| 437 | len = sizeof(addr); |
| 438 | newsock = accept(ch->sock, &addr, &len); |
| 439 | if (newsock < 0) |
| 440 | { |
| 441 | error("accept from auth socket: %.100s", strerror(errno)); |
| 442 | break; |
| 443 | } |
| 444 | |
| 445 | nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| 446 | xstrdup("accepted auth socket")); |
| 447 | packet_start(SSH_SMSG_AGENT_OPEN); |
| 448 | packet_put_int(nchan); |
| 449 | packet_send(); |
| 450 | } |
| 451 | break; |
| 452 | |
| 453 | case SSH_CHANNEL_OPEN: |
| 454 | /* This is an open two-way communication channel. It is not of |
| 455 | interest to us at this point what kind of data is being |
| 456 | transmitted. */ |
| 457 | |
| 458 | /* Read available incoming data and append it to buffer; |
| 459 | shutdown socket, if read or write failes */ |
| 460 | if (FD_ISSET(ch->sock, readset)) |
| 461 | { |
| 462 | len = read(ch->sock, buf, sizeof(buf)); |
| 463 | if (len <= 0) |
| 464 | { |
| 465 | if (compat13) { |
| 466 | buffer_consume(&ch->output, buffer_len(&ch->output)); |
| 467 | ch->type = SSH_CHANNEL_INPUT_DRAINING; |
| 468 | debug("Channel %d status set to input draining.", i); |
| 469 | }else{ |
| 470 | chan_read_failed(ch); |
| 471 | } |
| 472 | break; |
| 473 | } |
| 474 | buffer_append(&ch->input, buf, len); |
| 475 | } |
| 476 | /* Send buffered output data to the socket. */ |
| 477 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) |
| 478 | { |
| 479 | len = write(ch->sock, buffer_ptr(&ch->output), |
| 480 | buffer_len(&ch->output)); |
| 481 | if (len <= 0) |
| 482 | { |
| 483 | if (compat13) { |
| 484 | buffer_consume(&ch->output, buffer_len(&ch->output)); |
| 485 | debug("Channel %d status set to input draining.", i); |
| 486 | ch->type = SSH_CHANNEL_INPUT_DRAINING; |
| 487 | }else{ |
| 488 | chan_write_failed(ch); |
| 489 | } |
| 490 | break; |
| 491 | } |
| 492 | buffer_consume(&ch->output, len); |
| 493 | } |
| 494 | break; |
| 495 | |
| 496 | case SSH_CHANNEL_OUTPUT_DRAINING: |
| 497 | if (!compat13) |
| 498 | fatal("cannot happen: OUT_DRAIN"); |
| 499 | /* Send buffered output data to the socket. */ |
| 500 | if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) |
| 501 | { |
| 502 | len = write(ch->sock, buffer_ptr(&ch->output), |
| 503 | buffer_len(&ch->output)); |
| 504 | if (len <= 0) |
| 505 | buffer_consume(&ch->output, buffer_len(&ch->output)); |
| 506 | else |
| 507 | buffer_consume(&ch->output, len); |
| 508 | } |
| 509 | break; |
| 510 | |
| 511 | case SSH_CHANNEL_X11_OPEN: |
| 512 | case SSH_CHANNEL_FREE: |
| 513 | default: |
| 514 | continue; |
| 515 | } |
| 516 | } |
| 517 | } |
| 518 | |
| 519 | /* If there is data to send to the connection, send some of it now. */ |
| 520 | |
| 521 | void channel_output_poll() |
| 522 | { |
| 523 | int len, i; |
| 524 | Channel *ch; |
| 525 | |
| 526 | for (i = 0; i < channels_alloc; i++) |
| 527 | { |
| 528 | ch = &channels[i]; |
| 529 | /* We are only interested in channels that can have buffered incoming |
| 530 | data. */ |
| 531 | if (ch->type != SSH_CHANNEL_OPEN && |
| 532 | ch->type != SSH_CHANNEL_INPUT_DRAINING) |
| 533 | continue; |
| 534 | |
| 535 | /* Get the amount of buffered data for this channel. */ |
| 536 | len = buffer_len(&ch->input); |
| 537 | if (len > 0) |
| 538 | { |
| 539 | /* Send some data for the other side over the secure connection. */ |
| 540 | if (packet_is_interactive()) |
| 541 | { |
| 542 | if (len > 1024) |
| 543 | len = 512; |
| 544 | } |
| 545 | else |
| 546 | { |
| 547 | if (len > 16384) |
| 548 | len = 16384; /* Keep the packets at reasonable size. */ |
| 549 | } |
| 550 | packet_start(SSH_MSG_CHANNEL_DATA); |
| 551 | packet_put_int(ch->remote_id); |
| 552 | packet_put_string(buffer_ptr(&ch->input), len); |
| 553 | packet_send(); |
| 554 | buffer_consume(&ch->input, len); |
| 555 | } |
| 556 | else if(ch->istate == CHAN_INPUT_WAIT_DRAIN) |
| 557 | { |
| 558 | if (compat13) |
| 559 | fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); |
| 560 | /* input-buffer is empty and read-socket shutdown: |
| 561 | tell peer, that we will not send more data: send IEOF */ |
| 562 | chan_ibuf_empty(ch); |
| 563 | } |
| 564 | } |
| 565 | } |
| 566 | |
| 567 | /* This is called when a packet of type CHANNEL_DATA has just been received. |
| 568 | The message type has already been consumed, but channel number and data |
| 569 | is still there. */ |
| 570 | |
| 571 | void channel_input_data(int payload_len) |
| 572 | { |
| 573 | int channel; |
| 574 | char *data; |
| 575 | unsigned int data_len; |
| 576 | |
| 577 | /* Get the channel number and verify it. */ |
| 578 | channel = packet_get_int(); |
| 579 | if (channel < 0 || channel >= channels_alloc || |
| 580 | channels[channel].type == SSH_CHANNEL_FREE) |
| 581 | packet_disconnect("Received data for nonexistent channel %d.", channel); |
| 582 | |
| 583 | /* Ignore any data for non-open channels (might happen on close) */ |
| 584 | if (channels[channel].type != SSH_CHANNEL_OPEN && |
| 585 | channels[channel].type != SSH_CHANNEL_X11_OPEN) |
| 586 | return; |
| 587 | |
| 588 | /* Get the data. */ |
| 589 | data = packet_get_string(&data_len); |
| 590 | packet_integrity_check(payload_len, 4 + 4+data_len, SSH_MSG_CHANNEL_DATA); |
| 591 | buffer_append(&channels[channel].output, data, data_len); |
| 592 | xfree(data); |
| 593 | } |
| 594 | |
| 595 | /* Returns true if no channel has too much buffered data, and false if |
| 596 | one or more channel is overfull. */ |
| 597 | |
| 598 | int channel_not_very_much_buffered_data() |
| 599 | { |
| 600 | unsigned int i; |
| 601 | Channel *ch; |
| 602 | |
| 603 | for (i = 0; i < channels_alloc; i++) |
| 604 | { |
| 605 | ch = &channels[i]; |
| 606 | switch (ch->type) |
| 607 | { |
| 608 | case SSH_CHANNEL_X11_LISTENER: |
| 609 | case SSH_CHANNEL_PORT_LISTENER: |
| 610 | case SSH_CHANNEL_AUTH_SOCKET: |
| 611 | continue; |
| 612 | case SSH_CHANNEL_OPEN: |
| 613 | if (buffer_len(&ch->input) > 32768) |
| 614 | return 0; |
| 615 | if (buffer_len(&ch->output) > 32768) |
| 616 | return 0; |
| 617 | continue; |
| 618 | case SSH_CHANNEL_INPUT_DRAINING: |
| 619 | case SSH_CHANNEL_OUTPUT_DRAINING: |
| 620 | case SSH_CHANNEL_X11_OPEN: |
| 621 | case SSH_CHANNEL_FREE: |
| 622 | default: |
| 623 | continue; |
| 624 | } |
| 625 | } |
| 626 | return 1; |
| 627 | } |
| 628 | |
| 629 | /* This is called after receiving CHANNEL_CLOSE/IEOF. */ |
| 630 | |
| 631 | void channel_input_close() |
| 632 | { |
| 633 | int channel; |
| 634 | |
| 635 | /* Get the channel number and verify it. */ |
| 636 | channel = packet_get_int(); |
| 637 | if (channel < 0 || channel >= channels_alloc || |
| 638 | channels[channel].type == SSH_CHANNEL_FREE) |
| 639 | packet_disconnect("Received data for nonexistent channel %d.", channel); |
| 640 | |
| 641 | if(!compat13){ |
| 642 | /* proto version 1.5 overloads CLOSE with IEOF */ |
| 643 | chan_rcvd_ieof(&channels[channel]); |
| 644 | return; |
| 645 | } |
| 646 | |
| 647 | /* Send a confirmation that we have closed the channel and no more data is |
| 648 | coming for it. */ |
| 649 | packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); |
| 650 | packet_put_int(channels[channel].remote_id); |
| 651 | packet_send(); |
| 652 | |
| 653 | /* If the channel is in closed state, we have sent a close request, and |
| 654 | the other side will eventually respond with a confirmation. Thus, |
| 655 | we cannot free the channel here, because then there would be no-one to |
| 656 | receive the confirmation. The channel gets freed when the confirmation |
| 657 | arrives. */ |
| 658 | if (channels[channel].type != SSH_CHANNEL_CLOSED) |
| 659 | { |
| 660 | /* Not a closed channel - mark it as draining, which will cause it to |
| 661 | be freed later. */ |
| 662 | buffer_consume(&channels[channel].input, |
| 663 | buffer_len(&channels[channel].input)); |
| 664 | channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; |
| 665 | /* debug("Setting status to output draining; output len = %d", |
| 666 | buffer_len(&channels[channel].output)); */ |
| 667 | } |
| 668 | } |
| 669 | |
| 670 | /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ |
| 671 | |
| 672 | void channel_input_close_confirmation() |
| 673 | { |
| 674 | int channel; |
| 675 | |
| 676 | /* Get the channel number and verify it. */ |
| 677 | channel = packet_get_int(); |
| 678 | if (channel < 0 || channel >= channels_alloc) |
| 679 | packet_disconnect("Received close confirmation for out-of-range channel %d.", |
| 680 | channel); |
| 681 | |
| 682 | if(!compat13){ |
| 683 | /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ |
| 684 | chan_rcvd_oclose(&channels[channel]); |
| 685 | return; |
| 686 | } |
| 687 | |
| 688 | if (channels[channel].type != SSH_CHANNEL_CLOSED) |
| 689 | packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", |
| 690 | channel, channels[channel].type); |
| 691 | |
| 692 | /* Free the channel. */ |
| 693 | channel_free(channel); |
| 694 | } |
| 695 | |
| 696 | /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ |
| 697 | |
| 698 | void channel_input_open_confirmation() |
| 699 | { |
| 700 | int channel, remote_channel; |
| 701 | |
| 702 | /* Get the channel number and verify it. */ |
| 703 | channel = packet_get_int(); |
| 704 | if (channel < 0 || channel >= channels_alloc || |
| 705 | channels[channel].type != SSH_CHANNEL_OPENING) |
| 706 | packet_disconnect("Received open confirmation for non-opening channel %d.", |
| 707 | channel); |
| 708 | |
| 709 | /* Get remote side's id for this channel. */ |
| 710 | remote_channel = packet_get_int(); |
| 711 | |
| 712 | /* Record the remote channel number and mark that the channel is now open. */ |
| 713 | channels[channel].remote_id = remote_channel; |
| 714 | channels[channel].type = SSH_CHANNEL_OPEN; |
| 715 | } |
| 716 | |
| 717 | /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ |
| 718 | |
| 719 | void channel_input_open_failure() |
| 720 | { |
| 721 | int channel; |
| 722 | |
| 723 | /* Get the channel number and verify it. */ |
| 724 | channel = packet_get_int(); |
| 725 | if (channel < 0 || channel >= channels_alloc || |
| 726 | channels[channel].type != SSH_CHANNEL_OPENING) |
| 727 | packet_disconnect("Received open failure for non-opening channel %d.", |
| 728 | channel); |
| 729 | |
| 730 | /* Free the channel. This will also close the socket. */ |
| 731 | channel_free(channel); |
| 732 | } |
| 733 | |
| 734 | /* Stops listening for channels, and removes any unix domain sockets that |
| 735 | we might have. */ |
| 736 | |
| 737 | void channel_stop_listening() |
| 738 | { |
| 739 | int i; |
| 740 | for (i = 0; i < channels_alloc; i++) |
| 741 | { |
| 742 | switch (channels[i].type) |
| 743 | { |
| 744 | case SSH_CHANNEL_AUTH_SOCKET: |
| 745 | close(channels[i].sock); |
| 746 | remove(channels[i].path); |
| 747 | channel_free(i); |
| 748 | break; |
| 749 | case SSH_CHANNEL_PORT_LISTENER: |
| 750 | case SSH_CHANNEL_X11_LISTENER: |
| 751 | close(channels[i].sock); |
| 752 | channel_free(i); |
| 753 | break; |
| 754 | default: |
| 755 | break; |
| 756 | } |
| 757 | } |
| 758 | } |
| 759 | |
| 760 | /* Closes the sockets of all channels. This is used to close extra file |
| 761 | descriptors after a fork. */ |
| 762 | |
| 763 | void channel_close_all() |
| 764 | { |
| 765 | int i; |
| 766 | for (i = 0; i < channels_alloc; i++) |
| 767 | { |
| 768 | if (channels[i].type != SSH_CHANNEL_FREE) |
| 769 | close(channels[i].sock); |
| 770 | } |
| 771 | } |
| 772 | |
| 773 | /* Returns the maximum file descriptor number used by the channels. */ |
| 774 | |
| 775 | int channel_max_fd() |
| 776 | { |
| 777 | return channel_max_fd_value; |
| 778 | } |
| 779 | |
| 780 | /* Returns true if any channel is still open. */ |
| 781 | |
| 782 | int channel_still_open() |
| 783 | { |
| 784 | unsigned int i; |
| 785 | for (i = 0; i < channels_alloc; i++) |
| 786 | switch (channels[i].type) |
| 787 | { |
| 788 | case SSH_CHANNEL_FREE: |
| 789 | case SSH_CHANNEL_X11_LISTENER: |
| 790 | case SSH_CHANNEL_PORT_LISTENER: |
| 791 | case SSH_CHANNEL_CLOSED: |
| 792 | case SSH_CHANNEL_AUTH_SOCKET: |
| 793 | continue; |
| 794 | case SSH_CHANNEL_OPENING: |
| 795 | case SSH_CHANNEL_OPEN: |
| 796 | case SSH_CHANNEL_X11_OPEN: |
| 797 | return 1; |
| 798 | case SSH_CHANNEL_INPUT_DRAINING: |
| 799 | case SSH_CHANNEL_OUTPUT_DRAINING: |
| 800 | if (!compat13) |
| 801 | fatal("cannot happen: OUT_DRAIN"); |
| 802 | return 1; |
| 803 | default: |
| 804 | fatal("channel_still_open: bad channel type %d", channels[i].type); |
| 805 | /*NOTREACHED*/ |
| 806 | } |
| 807 | return 0; |
| 808 | } |
| 809 | |
| 810 | /* Returns a message describing the currently open forwarded |
| 811 | connections, suitable for sending to the client. The message |
| 812 | contains crlf pairs for newlines. */ |
| 813 | |
| 814 | char *channel_open_message() |
| 815 | { |
| 816 | Buffer buffer; |
| 817 | int i; |
| 818 | char buf[512], *cp; |
| 819 | |
| 820 | buffer_init(&buffer); |
| 821 | snprintf(buf, sizeof buf, "The following connections are open:\r\n"); |
| 822 | buffer_append(&buffer, buf, strlen(buf)); |
| 823 | for (i = 0; i < channels_alloc; i++){ |
| 824 | Channel *c=&channels[i]; |
| 825 | switch (c->type) |
| 826 | { |
| 827 | case SSH_CHANNEL_FREE: |
| 828 | case SSH_CHANNEL_X11_LISTENER: |
| 829 | case SSH_CHANNEL_PORT_LISTENER: |
| 830 | case SSH_CHANNEL_CLOSED: |
| 831 | case SSH_CHANNEL_AUTH_SOCKET: |
| 832 | continue; |
| 833 | case SSH_CHANNEL_OPENING: |
| 834 | case SSH_CHANNEL_OPEN: |
| 835 | case SSH_CHANNEL_X11_OPEN: |
| 836 | case SSH_CHANNEL_INPUT_DRAINING: |
| 837 | case SSH_CHANNEL_OUTPUT_DRAINING: |
Damien Miller | 01ab4a2 | 1999-10-28 15:23:30 +1000 | [diff] [blame] | 838 | snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n", |
| 839 | c->self,c->remote_name, |
| 840 | c->type,c->remote_id, c->istate,c->ostate); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 841 | buffer_append(&buffer, buf, strlen(buf)); |
| 842 | continue; |
| 843 | default: |
| 844 | fatal("channel_still_open: bad channel type %d", c->type); |
| 845 | /*NOTREACHED*/ |
| 846 | } |
| 847 | } |
| 848 | buffer_append(&buffer, "\0", 1); |
| 849 | cp = xstrdup(buffer_ptr(&buffer)); |
| 850 | buffer_free(&buffer); |
| 851 | return cp; |
| 852 | } |
| 853 | |
| 854 | /* Initiate forwarding of connections to local port "port" through the secure |
| 855 | channel to host:port from remote side. */ |
| 856 | |
| 857 | void channel_request_local_forwarding(int port, const char *host, |
| 858 | int host_port) |
| 859 | { |
| 860 | int ch, sock; |
| 861 | struct sockaddr_in sin; |
| 862 | extern Options options; |
| 863 | |
| 864 | if (strlen(host) > sizeof(channels[0].path) - 1) |
| 865 | packet_disconnect("Forward host name too long."); |
| 866 | |
| 867 | /* Create a port to listen for the host. */ |
| 868 | sock = socket(AF_INET, SOCK_STREAM, 0); |
| 869 | if (sock < 0) |
| 870 | packet_disconnect("socket: %.100s", strerror(errno)); |
| 871 | |
| 872 | /* Initialize socket address. */ |
| 873 | memset(&sin, 0, sizeof(sin)); |
| 874 | sin.sin_family = AF_INET; |
| 875 | if (options.gateway_ports == 1) |
| 876 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
| 877 | else |
| 878 | sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); |
| 879 | sin.sin_port = htons(port); |
| 880 | |
| 881 | /* Bind the socket to the address. */ |
| 882 | if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
| 883 | packet_disconnect("bind: %.100s", strerror(errno)); |
| 884 | |
| 885 | /* Start listening for connections on the socket. */ |
| 886 | if (listen(sock, 5) < 0) |
| 887 | packet_disconnect("listen: %.100s", strerror(errno)); |
| 888 | |
| 889 | /* Allocate a channel number for the socket. */ |
| 890 | ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, |
| 891 | xstrdup("port listener")); |
| 892 | strcpy(channels[ch].path, host); /* note: host name stored here */ |
| 893 | channels[ch].host_port = host_port; /* port on host to connect to */ |
| 894 | channels[ch].listening_port = port; /* port being listened */ |
| 895 | } |
| 896 | |
| 897 | /* Initiate forwarding of connections to port "port" on remote host through |
| 898 | the secure channel to host:port from local side. */ |
| 899 | |
| 900 | void channel_request_remote_forwarding(int port, const char *host, |
| 901 | int remote_port) |
| 902 | { |
| 903 | int payload_len; |
| 904 | /* Record locally that connection to this host/port is permitted. */ |
| 905 | if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) |
| 906 | fatal("channel_request_remote_forwarding: too many forwards"); |
| 907 | permitted_opens[num_permitted_opens].host = xstrdup(host); |
| 908 | permitted_opens[num_permitted_opens].port = remote_port; |
| 909 | num_permitted_opens++; |
| 910 | |
| 911 | /* Send the forward request to the remote side. */ |
| 912 | packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); |
| 913 | packet_put_int(port); |
| 914 | packet_put_string(host, strlen(host)); |
| 915 | packet_put_int(remote_port); |
| 916 | packet_send(); |
| 917 | packet_write_wait(); |
| 918 | |
| 919 | /* Wait for response from the remote side. It will send a disconnect |
| 920 | message on failure, and we will never see it here. */ |
| 921 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); |
| 922 | } |
| 923 | |
| 924 | /* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates |
| 925 | listening for the port, and sends back a success reply (or disconnect |
| 926 | message if there was an error). This never returns if there was an |
| 927 | error. */ |
| 928 | |
| 929 | void channel_input_port_forward_request(int is_root) |
| 930 | { |
| 931 | int port, host_port; |
| 932 | char *hostname; |
| 933 | |
| 934 | /* Get arguments from the packet. */ |
| 935 | port = packet_get_int(); |
| 936 | hostname = packet_get_string(NULL); |
| 937 | host_port = packet_get_int(); |
| 938 | |
| 939 | /* Port numbers are 16 bit quantities. */ |
| 940 | if ((port & 0xffff) != port) |
| 941 | packet_disconnect("Requested forwarding of nonexistent port %d.", port); |
| 942 | |
| 943 | /* Check that an unprivileged user is not trying to forward a privileged |
| 944 | port. */ |
| 945 | if (port < IPPORT_RESERVED && !is_root) |
| 946 | packet_disconnect("Requested forwarding of port %d but user is not root.", |
| 947 | port); |
| 948 | |
| 949 | /* Initiate forwarding. */ |
| 950 | channel_request_local_forwarding(port, hostname, host_port); |
| 951 | |
| 952 | /* Free the argument string. */ |
| 953 | xfree(hostname); |
| 954 | } |
| 955 | |
| 956 | /* This is called after receiving PORT_OPEN message. This attempts to connect |
| 957 | to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or |
| 958 | CHANNEL_OPEN_FAILURE. */ |
| 959 | |
| 960 | void channel_input_port_open(int payload_len) |
| 961 | { |
| 962 | int remote_channel, sock, newch, host_port, i; |
| 963 | struct sockaddr_in sin; |
| 964 | char *host, *originator_string; |
| 965 | struct hostent *hp; |
| 966 | int host_len, originator_len; |
| 967 | |
| 968 | /* Get remote channel number. */ |
| 969 | remote_channel = packet_get_int(); |
| 970 | |
| 971 | /* Get host name to connect to. */ |
| 972 | host = packet_get_string(&host_len); |
| 973 | |
| 974 | /* Get port to connect to. */ |
| 975 | host_port = packet_get_int(); |
| 976 | |
| 977 | /* Get remote originator name. */ |
| 978 | if (have_hostname_in_open) |
| 979 | originator_string = packet_get_string(&originator_len); |
| 980 | else |
| 981 | originator_string = xstrdup("unknown (remote did not supply name)"); |
| 982 | |
| 983 | packet_integrity_check(payload_len, |
| 984 | 4 + 4 + host_len + 4 + 4 + originator_len, |
| 985 | SSH_MSG_PORT_OPEN); |
| 986 | |
| 987 | /* Check if opening that port is permitted. */ |
| 988 | if (!all_opens_permitted) |
| 989 | { |
| 990 | /* Go trough all permitted ports. */ |
| 991 | for (i = 0; i < num_permitted_opens; i++) |
| 992 | if (permitted_opens[i].port == host_port && |
| 993 | strcmp(permitted_opens[i].host, host) == 0) |
| 994 | break; |
| 995 | |
| 996 | /* Check if we found the requested port among those permitted. */ |
| 997 | if (i >= num_permitted_opens) |
| 998 | { |
| 999 | /* The port is not permitted. */ |
| 1000 | log("Received request to connect to %.100s:%d, but the request was denied.", |
| 1001 | host, host_port); |
| 1002 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| 1003 | packet_put_int(remote_channel); |
| 1004 | packet_send(); |
| 1005 | } |
| 1006 | } |
| 1007 | |
| 1008 | memset(&sin, 0, sizeof(sin)); |
| 1009 | sin.sin_addr.s_addr = inet_addr(host); |
| 1010 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) |
| 1011 | { |
| 1012 | /* It was a valid numeric host address. */ |
| 1013 | sin.sin_family = AF_INET; |
| 1014 | } |
| 1015 | else |
| 1016 | { |
| 1017 | /* Look up the host address from the name servers. */ |
| 1018 | hp = gethostbyname(host); |
| 1019 | if (!hp) |
| 1020 | { |
| 1021 | error("%.100s: unknown host.", host); |
| 1022 | goto fail; |
| 1023 | } |
| 1024 | if (!hp->h_addr_list[0]) |
| 1025 | { |
| 1026 | error("%.100s: host has no IP address.", host); |
| 1027 | goto fail; |
| 1028 | } |
| 1029 | sin.sin_family = hp->h_addrtype; |
| 1030 | memcpy(&sin.sin_addr, hp->h_addr_list[0], |
| 1031 | sizeof(sin.sin_addr)); |
| 1032 | } |
| 1033 | sin.sin_port = htons(host_port); |
| 1034 | |
| 1035 | /* Create the socket. */ |
| 1036 | sock = socket(sin.sin_family, SOCK_STREAM, 0); |
| 1037 | if (sock < 0) |
| 1038 | { |
| 1039 | error("socket: %.100s", strerror(errno)); |
| 1040 | goto fail; |
| 1041 | } |
| 1042 | |
| 1043 | /* Connect to the host/port. */ |
| 1044 | if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
| 1045 | { |
| 1046 | error("connect %.100s:%d: %.100s", host, host_port, |
| 1047 | strerror(errno)); |
| 1048 | close(sock); |
| 1049 | goto fail; |
| 1050 | } |
| 1051 | |
| 1052 | /* Successful connection. */ |
| 1053 | |
| 1054 | /* Allocate a channel for this connection. */ |
| 1055 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); |
| 1056 | channels[newch].remote_id = remote_channel; |
| 1057 | |
| 1058 | /* Send a confirmation to the remote host. */ |
| 1059 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); |
| 1060 | packet_put_int(remote_channel); |
| 1061 | packet_put_int(newch); |
| 1062 | packet_send(); |
| 1063 | |
| 1064 | /* Free the argument string. */ |
| 1065 | xfree(host); |
| 1066 | |
| 1067 | return; |
| 1068 | |
| 1069 | fail: |
| 1070 | /* Free the argument string. */ |
| 1071 | xfree(host); |
| 1072 | |
| 1073 | /* Send refusal to the remote host. */ |
| 1074 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| 1075 | packet_put_int(remote_channel); |
| 1076 | packet_send(); |
| 1077 | } |
| 1078 | |
| 1079 | /* Creates an internet domain socket for listening for X11 connections. |
| 1080 | Returns a suitable value for the DISPLAY variable, or NULL if an error |
| 1081 | occurs. */ |
| 1082 | |
| 1083 | char *x11_create_display_inet(int screen_number) |
| 1084 | { |
| 1085 | extern ServerOptions options; |
| 1086 | int display_number, port, sock; |
| 1087 | struct sockaddr_in sin; |
| 1088 | char buf[512]; |
| 1089 | char hostname[MAXHOSTNAMELEN]; |
| 1090 | |
| 1091 | for (display_number = options.x11_display_offset; display_number < MAX_DISPLAYS; display_number++) |
| 1092 | { |
| 1093 | port = 6000 + display_number; |
| 1094 | memset(&sin, 0, sizeof(sin)); |
| 1095 | sin.sin_family = AF_INET; |
| 1096 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
| 1097 | sin.sin_port = htons(port); |
| 1098 | |
| 1099 | sock = socket(AF_INET, SOCK_STREAM, 0); |
| 1100 | if (sock < 0) |
| 1101 | { |
| 1102 | error("socket: %.100s", strerror(errno)); |
| 1103 | return NULL; |
| 1104 | } |
| 1105 | |
| 1106 | if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
| 1107 | { |
| 1108 | debug("bind port %d: %.100s", port, strerror(errno)); |
| 1109 | shutdown(sock, SHUT_RDWR); |
| 1110 | close(sock); |
| 1111 | continue; |
| 1112 | } |
| 1113 | break; |
| 1114 | } |
| 1115 | if (display_number >= MAX_DISPLAYS) |
| 1116 | { |
| 1117 | error("Failed to allocate internet-domain X11 display socket."); |
| 1118 | return NULL; |
| 1119 | } |
| 1120 | |
| 1121 | /* Start listening for connections on the socket. */ |
| 1122 | if (listen(sock, 5) < 0) |
| 1123 | { |
| 1124 | error("listen: %.100s", strerror(errno)); |
| 1125 | shutdown(sock, SHUT_RDWR); |
| 1126 | close(sock); |
| 1127 | return NULL; |
| 1128 | } |
| 1129 | |
| 1130 | /* Set up a suitable value for the DISPLAY variable. */ |
| 1131 | if (gethostname(hostname, sizeof(hostname)) < 0) |
| 1132 | fatal("gethostname: %.100s", strerror(errno)); |
| 1133 | snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname, |
| 1134 | display_number, screen_number); |
| 1135 | |
| 1136 | /* Allocate a channel for the socket. */ |
| 1137 | (void)channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, |
| 1138 | xstrdup("X11 inet listener")); |
| 1139 | |
| 1140 | /* Return a suitable value for the DISPLAY environment variable. */ |
| 1141 | return xstrdup(buf); |
| 1142 | } |
| 1143 | |
| 1144 | #ifndef X_UNIX_PATH |
| 1145 | #define X_UNIX_PATH "/tmp/.X11-unix/X" |
| 1146 | #endif |
| 1147 | |
| 1148 | static |
| 1149 | int |
| 1150 | connect_local_xsocket(unsigned dnr) |
| 1151 | { |
| 1152 | static const char *const x_sockets[] = { |
| 1153 | X_UNIX_PATH "%u", |
| 1154 | "/var/X/.X11-unix/X" "%u", |
| 1155 | "/usr/spool/sockets/X11/" "%u", |
| 1156 | NULL |
| 1157 | }; |
| 1158 | int sock; |
| 1159 | struct sockaddr_un addr; |
| 1160 | const char *const *path; |
| 1161 | |
| 1162 | for (path = x_sockets; *path; ++path) |
| 1163 | { |
| 1164 | sock = socket(AF_UNIX, SOCK_STREAM, 0); |
| 1165 | if (sock < 0) |
| 1166 | error("socket: %.100s", strerror(errno)); |
| 1167 | memset(&addr, 0, sizeof(addr)); |
| 1168 | addr.sun_family = AF_UNIX; |
| 1169 | snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr); |
| 1170 | if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) |
| 1171 | return sock; |
| 1172 | close(sock); |
| 1173 | } |
| 1174 | error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); |
| 1175 | return -1; |
| 1176 | } |
| 1177 | |
| 1178 | |
| 1179 | /* This is called when SSH_SMSG_X11_OPEN is received. The packet contains |
| 1180 | the remote channel number. We should do whatever we want, and respond |
| 1181 | with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ |
| 1182 | |
| 1183 | void x11_input_open(int payload_len) |
| 1184 | { |
| 1185 | int remote_channel, display_number, sock, newch; |
| 1186 | const char *display; |
| 1187 | struct sockaddr_in sin; |
| 1188 | char buf[1024], *cp, *remote_host; |
| 1189 | struct hostent *hp; |
| 1190 | int remote_len; |
| 1191 | |
| 1192 | /* Get remote channel number. */ |
| 1193 | remote_channel = packet_get_int(); |
| 1194 | |
| 1195 | /* Get remote originator name. */ |
| 1196 | if (have_hostname_in_open) |
| 1197 | remote_host = packet_get_string(&remote_len); |
| 1198 | else |
| 1199 | remote_host = xstrdup("unknown (remote did not supply name)"); |
| 1200 | |
| 1201 | debug("Received X11 open request."); |
| 1202 | packet_integrity_check(payload_len, 4 + 4+remote_len, SSH_SMSG_X11_OPEN); |
| 1203 | |
| 1204 | /* Try to open a socket for the local X server. */ |
| 1205 | display = getenv("DISPLAY"); |
| 1206 | if (!display) |
| 1207 | { |
| 1208 | error("DISPLAY not set."); |
| 1209 | goto fail; |
| 1210 | } |
| 1211 | |
| 1212 | /* Now we decode the value of the DISPLAY variable and make a connection |
| 1213 | to the real X server. */ |
| 1214 | |
| 1215 | /* Check if it is a unix domain socket. Unix domain displays are in one |
| 1216 | of the following formats: unix:d[.s], :d[.s], ::d[.s] */ |
| 1217 | if (strncmp(display, "unix:", 5) == 0 || |
| 1218 | display[0] == ':') |
| 1219 | { |
| 1220 | /* Connect to the unix domain socket. */ |
| 1221 | if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) |
| 1222 | { |
| 1223 | error("Could not parse display number from DISPLAY: %.100s", |
| 1224 | display); |
| 1225 | goto fail; |
| 1226 | } |
| 1227 | /* Create a socket. */ |
| 1228 | sock = connect_local_xsocket(display_number); |
| 1229 | if (sock < 0) |
| 1230 | goto fail; |
| 1231 | |
| 1232 | /* OK, we now have a connection to the display. */ |
| 1233 | goto success; |
| 1234 | } |
| 1235 | |
| 1236 | /* Connect to an inet socket. The DISPLAY value is supposedly |
| 1237 | hostname:d[.s], where hostname may also be numeric IP address. */ |
| 1238 | strncpy(buf, display, sizeof(buf)); |
| 1239 | buf[sizeof(buf) - 1] = 0; |
| 1240 | cp = strchr(buf, ':'); |
| 1241 | if (!cp) |
| 1242 | { |
| 1243 | error("Could not find ':' in DISPLAY: %.100s", display); |
| 1244 | goto fail; |
| 1245 | } |
| 1246 | *cp = 0; |
| 1247 | /* buf now contains the host name. But first we parse the display number. */ |
| 1248 | if (sscanf(cp + 1, "%d", &display_number) != 1) |
| 1249 | { |
| 1250 | error("Could not parse display number from DISPLAY: %.100s", |
| 1251 | display); |
| 1252 | goto fail; |
| 1253 | } |
| 1254 | |
| 1255 | /* Try to parse the host name as a numeric IP address. */ |
| 1256 | memset(&sin, 0, sizeof(sin)); |
| 1257 | sin.sin_addr.s_addr = inet_addr(buf); |
| 1258 | if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) |
| 1259 | { |
| 1260 | /* It was a valid numeric host address. */ |
| 1261 | sin.sin_family = AF_INET; |
| 1262 | } |
| 1263 | else |
| 1264 | { |
| 1265 | /* Not a numeric IP address. */ |
| 1266 | /* Look up the host address from the name servers. */ |
| 1267 | hp = gethostbyname(buf); |
| 1268 | if (!hp) |
| 1269 | { |
| 1270 | error("%.100s: unknown host.", buf); |
| 1271 | goto fail; |
| 1272 | } |
| 1273 | if (!hp->h_addr_list[0]) |
| 1274 | { |
| 1275 | error("%.100s: host has no IP address.", buf); |
| 1276 | goto fail; |
| 1277 | } |
| 1278 | sin.sin_family = hp->h_addrtype; |
| 1279 | memcpy(&sin.sin_addr, hp->h_addr_list[0], |
| 1280 | sizeof(sin.sin_addr)); |
| 1281 | } |
| 1282 | /* Set port number. */ |
| 1283 | sin.sin_port = htons(6000 + display_number); |
| 1284 | |
| 1285 | /* Create a socket. */ |
| 1286 | sock = socket(sin.sin_family, SOCK_STREAM, 0); |
| 1287 | if (sock < 0) |
| 1288 | { |
| 1289 | error("socket: %.100s", strerror(errno)); |
| 1290 | goto fail; |
| 1291 | } |
| 1292 | /* Connect it to the display. */ |
| 1293 | if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
| 1294 | { |
| 1295 | error("connect %.100s:%d: %.100s", buf, 6000 + display_number, |
| 1296 | strerror(errno)); |
| 1297 | close(sock); |
| 1298 | goto fail; |
| 1299 | } |
| 1300 | |
| 1301 | success: |
| 1302 | /* We have successfully obtained a connection to the real X display. */ |
| 1303 | |
| 1304 | /* Allocate a channel for this connection. */ |
| 1305 | if (x11_saved_proto == NULL) |
| 1306 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); |
| 1307 | else |
| 1308 | newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host); |
| 1309 | channels[newch].remote_id = remote_channel; |
| 1310 | |
| 1311 | /* Send a confirmation to the remote host. */ |
| 1312 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); |
| 1313 | packet_put_int(remote_channel); |
| 1314 | packet_put_int(newch); |
| 1315 | packet_send(); |
| 1316 | |
| 1317 | return; |
| 1318 | |
| 1319 | fail: |
| 1320 | /* Send refusal to the remote host. */ |
| 1321 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| 1322 | packet_put_int(remote_channel); |
| 1323 | packet_send(); |
| 1324 | } |
| 1325 | |
| 1326 | /* Requests forwarding of X11 connections, generates fake authentication |
| 1327 | data, and enables authentication spoofing. */ |
| 1328 | |
| 1329 | void x11_request_forwarding_with_spoofing(const char *proto, const char *data) |
| 1330 | { |
| 1331 | unsigned int data_len = (unsigned int)strlen(data) / 2; |
| 1332 | unsigned int i, value; |
| 1333 | char *new_data; |
| 1334 | int screen_number; |
| 1335 | const char *cp; |
| 1336 | u_int32_t rand = 0; |
| 1337 | |
| 1338 | cp = getenv("DISPLAY"); |
| 1339 | if (cp) |
| 1340 | cp = strchr(cp, ':'); |
| 1341 | if (cp) |
| 1342 | cp = strchr(cp, '.'); |
| 1343 | if (cp) |
| 1344 | screen_number = atoi(cp + 1); |
| 1345 | else |
| 1346 | screen_number = 0; |
| 1347 | |
| 1348 | /* Save protocol name. */ |
| 1349 | x11_saved_proto = xstrdup(proto); |
| 1350 | |
| 1351 | /* Extract real authentication data and generate fake data of the same |
| 1352 | length. */ |
| 1353 | x11_saved_data = xmalloc(data_len); |
| 1354 | x11_fake_data = xmalloc(data_len); |
| 1355 | for (i = 0; i < data_len; i++) |
| 1356 | { |
| 1357 | if (sscanf(data + 2 * i, "%2x", &value) != 1) |
| 1358 | fatal("x11_request_forwarding: bad authentication data: %.100s", data); |
| 1359 | if (i % 4 == 0) |
| 1360 | rand = arc4random(); |
| 1361 | x11_saved_data[i] = value; |
| 1362 | x11_fake_data[i] = rand & 0xff; |
| 1363 | rand >>= 8; |
| 1364 | } |
| 1365 | x11_saved_data_len = data_len; |
| 1366 | x11_fake_data_len = data_len; |
| 1367 | |
| 1368 | /* Convert the fake data into hex. */ |
| 1369 | new_data = xmalloc(2 * data_len + 1); |
| 1370 | for (i = 0; i < data_len; i++) |
| 1371 | sprintf(new_data + 2 * i, "%02x", (unsigned char)x11_fake_data[i]); |
| 1372 | |
| 1373 | /* Send the request packet. */ |
| 1374 | packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); |
| 1375 | packet_put_string(proto, strlen(proto)); |
| 1376 | packet_put_string(new_data, strlen(new_data)); |
| 1377 | packet_put_int(screen_number); |
| 1378 | packet_send(); |
| 1379 | packet_write_wait(); |
| 1380 | xfree(new_data); |
| 1381 | } |
| 1382 | |
| 1383 | /* Sends a message to the server to request authentication fd forwarding. */ |
| 1384 | |
| 1385 | void auth_request_forwarding() |
| 1386 | { |
| 1387 | packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); |
| 1388 | packet_send(); |
| 1389 | packet_write_wait(); |
| 1390 | } |
| 1391 | |
| 1392 | /* Returns the name of the forwarded authentication socket. Returns NULL |
| 1393 | if there is no forwarded authentication socket. The returned value |
| 1394 | points to a static buffer. */ |
| 1395 | |
| 1396 | char *auth_get_socket_name() |
| 1397 | { |
| 1398 | return channel_forwarded_auth_socket_name; |
| 1399 | } |
| 1400 | |
| 1401 | /* removes the agent forwarding socket */ |
| 1402 | |
| 1403 | void cleanup_socket(void) { |
| 1404 | remove(channel_forwarded_auth_socket_name); |
| 1405 | rmdir(channel_forwarded_auth_socket_dir); |
| 1406 | } |
| 1407 | |
| 1408 | /* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. |
| 1409 | This starts forwarding authentication requests. */ |
| 1410 | |
| 1411 | void auth_input_request_forwarding(struct passwd *pw) |
| 1412 | { |
| 1413 | int sock, newch; |
| 1414 | struct sockaddr_un sunaddr; |
| 1415 | |
| 1416 | if (auth_get_socket_name() != NULL) |
| 1417 | fatal("Protocol error: authentication forwarding requested twice."); |
| 1418 | |
| 1419 | /* Temporarily drop privileged uid for mkdir/bind. */ |
| 1420 | temporarily_use_uid(pw->pw_uid); |
| 1421 | |
| 1422 | /* Allocate a buffer for the socket name, and format the name. */ |
| 1423 | channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); |
| 1424 | channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); |
| 1425 | strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); |
| 1426 | |
| 1427 | /* Create private directory for socket */ |
| 1428 | if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) |
| 1429 | packet_disconnect("mkdtemp: %.100s", strerror(errno)); |
| 1430 | snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, |
| 1431 | "%s/agent.%d", channel_forwarded_auth_socket_dir, (int)getpid()); |
| 1432 | |
| 1433 | if (atexit(cleanup_socket) < 0) { |
| 1434 | int saved=errno; |
| 1435 | cleanup_socket(); |
| 1436 | packet_disconnect("socket: %.100s", strerror(saved)); |
| 1437 | } |
| 1438 | |
| 1439 | /* Create the socket. */ |
| 1440 | sock = socket(AF_UNIX, SOCK_STREAM, 0); |
| 1441 | if (sock < 0) |
| 1442 | packet_disconnect("socket: %.100s", strerror(errno)); |
| 1443 | |
| 1444 | /* Bind it to the name. */ |
| 1445 | memset(&sunaddr, 0, sizeof(sunaddr)); |
| 1446 | sunaddr.sun_family = AF_UNIX; |
| 1447 | strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name, |
| 1448 | sizeof(sunaddr.sun_path)); |
| 1449 | |
| 1450 | if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) |
| 1451 | packet_disconnect("bind: %.100s", strerror(errno)); |
| 1452 | |
| 1453 | /* Restore the privileged uid. */ |
| 1454 | restore_uid(); |
| 1455 | |
| 1456 | /* Start listening on the socket. */ |
| 1457 | if (listen(sock, 5) < 0) |
| 1458 | packet_disconnect("listen: %.100s", strerror(errno)); |
| 1459 | |
| 1460 | /* Allocate a channel for the authentication agent socket. */ |
| 1461 | newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, |
| 1462 | xstrdup("auth socket")); |
| 1463 | strcpy(channels[newch].path, channel_forwarded_auth_socket_name); |
| 1464 | } |
| 1465 | |
| 1466 | /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ |
| 1467 | |
| 1468 | void auth_input_open_request() |
| 1469 | { |
| 1470 | int remch, sock, newch; |
| 1471 | char *dummyname; |
| 1472 | |
| 1473 | /* Read the remote channel number from the message. */ |
| 1474 | remch = packet_get_int(); |
| 1475 | |
| 1476 | /* Get a connection to the local authentication agent (this may again get |
| 1477 | forwarded). */ |
| 1478 | sock = ssh_get_authentication_socket(); |
| 1479 | |
| 1480 | /* If we could not connect the agent, send an error message back to |
| 1481 | the server. This should never happen unless the agent |
| 1482 | dies, because authentication forwarding is only enabled if we have an |
| 1483 | agent. */ |
| 1484 | if (sock < 0){ |
| 1485 | packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| 1486 | packet_put_int(remch); |
| 1487 | packet_send(); |
| 1488 | return; |
| 1489 | } |
| 1490 | |
| 1491 | debug("Forwarding authentication connection."); |
| 1492 | |
| 1493 | /* Dummy host name. This will be freed when the channel is freed; it will |
| 1494 | still be valid in the packet_put_string below since the channel cannot |
| 1495 | yet be freed at that point. */ |
| 1496 | dummyname = xstrdup("authentication agent connection"); |
| 1497 | |
| 1498 | newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); |
| 1499 | channels[newch].remote_id = remch; |
| 1500 | |
| 1501 | /* Send a confirmation to the remote host. */ |
| 1502 | packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); |
| 1503 | packet_put_int(remch); |
| 1504 | packet_put_int(newch); |
| 1505 | packet_send(); |
| 1506 | } |