1 /* $OpenBSD: serverloop.c,v 1.191 2017/02/01 02:59:09 dtucker Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Server main loop for handling the interactive session. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * SSH2 support by Markus Friedl. 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 40 #include <sys/types.h> 41 #include <sys/wait.h> 42 #include <sys/socket.h> 43 #ifdef HAVE_SYS_TIME_H 44 # include <sys/time.h> 45 #endif 46 47 #include <netinet/in.h> 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <pwd.h> 52 #include <signal.h> 53 #include <string.h> 54 #include <termios.h> 55 #include <unistd.h> 56 #include <stdarg.h> 57 58 #include "openbsd-compat/sys-queue.h" 59 #include "xmalloc.h" 60 #include "packet.h" 61 #include "buffer.h" 62 #include "log.h" 63 #include "misc.h" 64 #include "servconf.h" 65 #include "canohost.h" 66 #include "sshpty.h" 67 #include "channels.h" 68 #include "compat.h" 69 #include "ssh2.h" 70 #include "key.h" 71 #include "cipher.h" 72 #include "kex.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "session.h" 76 #include "dispatch.h" 77 #include "auth-options.h" 78 #include "serverloop.h" 79 #include "ssherr.h" 80 81 extern ServerOptions options; 82 83 /* XXX */ 84 extern Authctxt *the_authctxt; 85 extern int use_privsep; 86 87 static int no_more_sessions = 0; /* Disallow further sessions. */ 88 89 /* 90 * This SIGCHLD kludge is used to detect when the child exits. The server 91 * will exit after that, as soon as forwarded connections have terminated. 92 */ 93 94 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 95 96 /* Cleanup on signals (!use_privsep case only) */ 97 static volatile sig_atomic_t received_sigterm = 0; 98 99 /* prototypes */ 100 static void server_init_dispatch(void); 101 102 /* 103 * we write to this pipe if a SIGCHLD is caught in order to avoid 104 * the race between select() and child_terminated 105 */ 106 static int notify_pipe[2]; 107 static void 108 notify_setup(void) 109 { 110 if (pipe(notify_pipe) < 0) { 111 error("pipe(notify_pipe) failed %s", strerror(errno)); 112 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 113 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 114 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 115 close(notify_pipe[0]); 116 close(notify_pipe[1]); 117 } else { 118 set_nonblock(notify_pipe[0]); 119 set_nonblock(notify_pipe[1]); 120 return; 121 } 122 notify_pipe[0] = -1; /* read end */ 123 notify_pipe[1] = -1; /* write end */ 124 } 125 static void 126 notify_parent(void) 127 { 128 if (notify_pipe[1] != -1) 129 (void)write(notify_pipe[1], "", 1); 130 } 131 static void 132 notify_prepare(fd_set *readset) 133 { 134 if (notify_pipe[0] != -1) 135 FD_SET(notify_pipe[0], readset); 136 } 137 static void 138 notify_done(fd_set *readset) 139 { 140 char c; 141 142 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 143 while (read(notify_pipe[0], &c, 1) != -1) 144 debug2("notify_done: reading"); 145 } 146 147 /*ARGSUSED*/ 148 static void 149 sigchld_handler(int sig) 150 { 151 int save_errno = errno; 152 child_terminated = 1; 153 #ifndef _UNICOS 154 mysignal(SIGCHLD, sigchld_handler); 155 #endif 156 notify_parent(); 157 errno = save_errno; 158 } 159 160 /*ARGSUSED*/ 161 static void 162 sigterm_handler(int sig) 163 { 164 received_sigterm = sig; 165 } 166 167 static void 168 client_alive_check(void) 169 { 170 int channel_id; 171 172 /* timeout, check to see how many we have had */ 173 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 174 logit("Timeout, client not responding."); 175 cleanup_exit(255); 176 } 177 178 /* 179 * send a bogus global/channel request with "wantreply", 180 * we should get back a failure 181 */ 182 if ((channel_id = channel_find_open()) == -1) { 183 packet_start(SSH2_MSG_GLOBAL_REQUEST); 184 packet_put_cstring("keepalive (at) openssh.com"); 185 packet_put_char(1); /* boolean: want reply */ 186 } else { 187 channel_request_start(channel_id, "keepalive (at) openssh.com", 1); 188 } 189 packet_send(); 190 } 191 192 /* 193 * Sleep in select() until we can do something. This will initialize the 194 * select masks. Upon return, the masks will indicate which descriptors 195 * have data or can accept data. Optionally, a maximum time can be specified 196 * for the duration of the wait (0 = infinite). 197 */ 198 static void 199 wait_until_can_do_something(int connection_in, int connection_out, 200 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 201 u_int *nallocp, u_int64_t max_time_ms) 202 { 203 struct timeval tv, *tvp; 204 int ret; 205 time_t minwait_secs = 0; 206 int client_alive_scheduled = 0; 207 208 /* Allocate and update select() masks for channel descriptors. */ 209 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 210 &minwait_secs, 0); 211 212 /* XXX need proper deadline system for rekey/client alive */ 213 if (minwait_secs != 0) 214 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 215 216 /* 217 * if using client_alive, set the max timeout accordingly, 218 * and indicate that this particular timeout was for client 219 * alive by setting the client_alive_scheduled flag. 220 * 221 * this could be randomized somewhat to make traffic 222 * analysis more difficult, but we're not doing it yet. 223 */ 224 if (options.client_alive_interval) { 225 uint64_t keepalive_ms = 226 (uint64_t)options.client_alive_interval * 1000; 227 228 client_alive_scheduled = 1; 229 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 230 max_time_ms = keepalive_ms; 231 } 232 233 #if 0 234 /* wrong: bad condition XXX */ 235 if (channel_not_very_much_buffered_data()) 236 #endif 237 FD_SET(connection_in, *readsetp); 238 notify_prepare(*readsetp); 239 240 /* 241 * If we have buffered packet data going to the client, mark that 242 * descriptor. 243 */ 244 if (packet_have_data_to_write()) 245 FD_SET(connection_out, *writesetp); 246 247 /* 248 * If child has terminated and there is enough buffer space to read 249 * from it, then read as much as is available and exit. 250 */ 251 if (child_terminated && packet_not_very_much_data_to_write()) 252 if (max_time_ms == 0 || client_alive_scheduled) 253 max_time_ms = 100; 254 255 if (max_time_ms == 0) 256 tvp = NULL; 257 else { 258 tv.tv_sec = max_time_ms / 1000; 259 tv.tv_usec = 1000 * (max_time_ms % 1000); 260 tvp = &tv; 261 } 262 263 /* Wait for something to happen, or the timeout to expire. */ 264 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 265 266 if (ret == -1) { 267 memset(*readsetp, 0, *nallocp); 268 memset(*writesetp, 0, *nallocp); 269 if (errno != EINTR) 270 error("select: %.100s", strerror(errno)); 271 } else if (ret == 0 && client_alive_scheduled) 272 client_alive_check(); 273 274 notify_done(*readsetp); 275 } 276 277 /* 278 * Processes input from the client and the program. Input data is stored 279 * in buffers and processed later. 280 */ 281 static int 282 process_input(fd_set *readset, int connection_in) 283 { 284 struct ssh *ssh = active_state; /* XXX */ 285 int len; 286 char buf[16384]; 287 288 /* Read and buffer any input data from the client. */ 289 if (FD_ISSET(connection_in, readset)) { 290 len = read(connection_in, buf, sizeof(buf)); 291 if (len == 0) { 292 verbose("Connection closed by %.100s port %d", 293 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 294 return -1; 295 } else if (len < 0) { 296 if (errno != EINTR && errno != EAGAIN && 297 errno != EWOULDBLOCK) { 298 verbose("Read error from remote host " 299 "%.100s port %d: %.100s", 300 ssh_remote_ipaddr(ssh), 301 ssh_remote_port(ssh), strerror(errno)); 302 cleanup_exit(255); 303 } 304 } else { 305 /* Buffer any received data. */ 306 packet_process_incoming(buf, len); 307 } 308 } 309 return 0; 310 } 311 312 /* 313 * Sends data from internal buffers to client program stdin. 314 */ 315 static void 316 process_output(fd_set *writeset, int connection_out) 317 { 318 /* Send any buffered packet data to the client. */ 319 if (FD_ISSET(connection_out, writeset)) 320 packet_write_poll(); 321 } 322 323 static void 324 process_buffered_input_packets(void) 325 { 326 dispatch_run(DISPATCH_NONBLOCK, NULL, active_state); 327 } 328 329 static void 330 collect_children(void) 331 { 332 pid_t pid; 333 sigset_t oset, nset; 334 int status; 335 336 /* block SIGCHLD while we check for dead children */ 337 sigemptyset(&nset); 338 sigaddset(&nset, SIGCHLD); 339 sigprocmask(SIG_BLOCK, &nset, &oset); 340 if (child_terminated) { 341 debug("Received SIGCHLD."); 342 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 343 (pid < 0 && errno == EINTR)) 344 if (pid > 0) 345 session_close_by_pid(pid, status); 346 child_terminated = 0; 347 } 348 sigprocmask(SIG_SETMASK, &oset, NULL); 349 } 350 351 void 352 server_loop2(Authctxt *authctxt) 353 { 354 fd_set *readset = NULL, *writeset = NULL; 355 int max_fd; 356 u_int nalloc = 0, connection_in, connection_out; 357 u_int64_t rekey_timeout_ms = 0; 358 359 debug("Entering interactive session for SSH2."); 360 361 mysignal(SIGCHLD, sigchld_handler); 362 child_terminated = 0; 363 connection_in = packet_get_connection_in(); 364 connection_out = packet_get_connection_out(); 365 366 if (!use_privsep) { 367 signal(SIGTERM, sigterm_handler); 368 signal(SIGINT, sigterm_handler); 369 signal(SIGQUIT, sigterm_handler); 370 } 371 372 notify_setup(); 373 374 max_fd = MAXIMUM(connection_in, connection_out); 375 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 376 377 server_init_dispatch(); 378 379 for (;;) { 380 process_buffered_input_packets(); 381 382 if (!ssh_packet_is_rekeying(active_state) && 383 packet_not_very_much_data_to_write()) 384 channel_output_poll(); 385 if (options.rekey_interval > 0 && 386 !ssh_packet_is_rekeying(active_state)) 387 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 388 else 389 rekey_timeout_ms = 0; 390 391 wait_until_can_do_something(connection_in, connection_out, 392 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 393 394 if (received_sigterm) { 395 logit("Exiting on signal %d", (int)received_sigterm); 396 /* Clean up sessions, utmp, etc. */ 397 cleanup_exit(255); 398 } 399 400 collect_children(); 401 if (!ssh_packet_is_rekeying(active_state)) 402 channel_after_select(readset, writeset); 403 if (process_input(readset, connection_in) < 0) 404 break; 405 process_output(writeset, connection_out); 406 } 407 collect_children(); 408 409 free(readset); 410 free(writeset); 411 412 /* free all channels, no more reads and writes */ 413 channel_free_all(); 414 415 /* free remaining sessions, e.g. remove wtmp entries */ 416 session_destroy_all(NULL); 417 } 418 419 static int 420 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 421 { 422 debug("Got %d/%u for keepalive", type, seq); 423 /* 424 * reset timeout, since we got a sane answer from the client. 425 * even if this was generated by something other than 426 * the bogus CHANNEL_REQUEST we send for keepalives. 427 */ 428 packet_set_alive_timeouts(0); 429 return 0; 430 } 431 432 static Channel * 433 server_request_direct_tcpip(int *reason, const char **errmsg) 434 { 435 Channel *c = NULL; 436 char *target, *originator; 437 u_short target_port, originator_port; 438 439 target = packet_get_string(NULL); 440 target_port = packet_get_int(); 441 originator = packet_get_string(NULL); 442 originator_port = packet_get_int(); 443 packet_check_eom(); 444 445 debug("server_request_direct_tcpip: originator %s port %d, target %s " 446 "port %d", originator, originator_port, target, target_port); 447 448 /* XXX fine grained permissions */ 449 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 450 !no_port_forwarding_flag && !options.disable_forwarding) { 451 c = channel_connect_to_port(target, target_port, 452 "direct-tcpip", "direct-tcpip", reason, errmsg); 453 } else { 454 logit("refused local port forward: " 455 "originator %s port %d, target %s port %d", 456 originator, originator_port, target, target_port); 457 if (reason != NULL) 458 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 459 } 460 461 free(originator); 462 free(target); 463 464 return c; 465 } 466 467 static Channel * 468 server_request_direct_streamlocal(void) 469 { 470 Channel *c = NULL; 471 char *target, *originator; 472 u_short originator_port; 473 struct passwd *pw = the_authctxt->pw; 474 475 if (pw == NULL || !the_authctxt->valid) 476 fatal("server_input_global_request: no/invalid user"); 477 478 target = packet_get_string(NULL); 479 originator = packet_get_string(NULL); 480 originator_port = packet_get_int(); 481 packet_check_eom(); 482 483 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 484 originator, originator_port, target); 485 486 /* XXX fine grained permissions */ 487 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 488 !no_port_forwarding_flag && !options.disable_forwarding && 489 (pw->pw_uid == 0 || use_privsep)) { 490 c = channel_connect_to_path(target, 491 "direct-streamlocal (at) openssh.com", "direct-streamlocal"); 492 } else { 493 logit("refused streamlocal port forward: " 494 "originator %s port %d, target %s", 495 originator, originator_port, target); 496 } 497 498 free(originator); 499 free(target); 500 501 return c; 502 } 503 504 static Channel * 505 server_request_tun(void) 506 { 507 Channel *c = NULL; 508 int mode, tun; 509 int sock; 510 511 mode = packet_get_int(); 512 switch (mode) { 513 case SSH_TUNMODE_POINTOPOINT: 514 case SSH_TUNMODE_ETHERNET: 515 break; 516 default: 517 packet_send_debug("Unsupported tunnel device mode."); 518 return NULL; 519 } 520 if ((options.permit_tun & mode) == 0) { 521 packet_send_debug("Server has rejected tunnel device " 522 "forwarding"); 523 return NULL; 524 } 525 526 tun = packet_get_int(); 527 if (forced_tun_device != -1) { 528 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 529 goto done; 530 tun = forced_tun_device; 531 } 532 sock = tun_open(tun, mode); 533 if (sock < 0) 534 goto done; 535 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 536 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 537 c->datagram = 1; 538 #if defined(SSH_TUN_FILTER) 539 if (mode == SSH_TUNMODE_POINTOPOINT) 540 channel_register_filter(c->self, sys_tun_infilter, 541 sys_tun_outfilter, NULL, NULL); 542 #endif 543 544 done: 545 if (c == NULL) 546 packet_send_debug("Failed to open the tunnel device."); 547 return c; 548 } 549 550 static Channel * 551 server_request_session(void) 552 { 553 Channel *c; 554 555 debug("input_session_request"); 556 packet_check_eom(); 557 558 if (no_more_sessions) { 559 packet_disconnect("Possible attack: attempt to open a session " 560 "after additional sessions disabled"); 561 } 562 563 /* 564 * A server session has no fd to read or write until a 565 * CHANNEL_REQUEST for a shell is made, so we set the type to 566 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 567 * CHANNEL_REQUEST messages is registered. 568 */ 569 c = channel_new("session", SSH_CHANNEL_LARVAL, 570 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 571 0, "server-session", 1); 572 if (session_open(the_authctxt, c->self) != 1) { 573 debug("session open failed, free channel %d", c->self); 574 channel_free(c); 575 return NULL; 576 } 577 channel_register_cleanup(c->self, session_close_by_channel, 0); 578 return c; 579 } 580 581 static int 582 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 583 { 584 Channel *c = NULL; 585 char *ctype; 586 const char *errmsg = NULL; 587 int rchan, reason = SSH2_OPEN_CONNECT_FAILED; 588 u_int rmaxpack, rwindow, len; 589 590 ctype = packet_get_string(&len); 591 rchan = packet_get_int(); 592 rwindow = packet_get_int(); 593 rmaxpack = packet_get_int(); 594 595 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 596 ctype, rchan, rwindow, rmaxpack); 597 598 if (strcmp(ctype, "session") == 0) { 599 c = server_request_session(); 600 } else if (strcmp(ctype, "direct-tcpip") == 0) { 601 c = server_request_direct_tcpip(&reason, &errmsg); 602 } else if (strcmp(ctype, "direct-streamlocal (at) openssh.com") == 0) { 603 c = server_request_direct_streamlocal(); 604 } else if (strcmp(ctype, "tun (at) openssh.com") == 0) { 605 c = server_request_tun(); 606 } 607 if (c != NULL) { 608 debug("server_input_channel_open: confirm %s", ctype); 609 c->remote_id = rchan; 610 c->remote_window = rwindow; 611 c->remote_maxpacket = rmaxpack; 612 if (c->type != SSH_CHANNEL_CONNECTING) { 613 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 614 packet_put_int(c->remote_id); 615 packet_put_int(c->self); 616 packet_put_int(c->local_window); 617 packet_put_int(c->local_maxpacket); 618 packet_send(); 619 } 620 } else { 621 debug("server_input_channel_open: failure %s", ctype); 622 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 623 packet_put_int(rchan); 624 packet_put_int(reason); 625 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 626 packet_put_cstring(errmsg ? errmsg : "open failed"); 627 packet_put_cstring(""); 628 } 629 packet_send(); 630 } 631 free(ctype); 632 return 0; 633 } 634 635 static int 636 server_input_hostkeys_prove(struct sshbuf **respp) 637 { 638 struct ssh *ssh = active_state; /* XXX */ 639 struct sshbuf *resp = NULL; 640 struct sshbuf *sigbuf = NULL; 641 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 642 int r, ndx, success = 0; 643 const u_char *blob; 644 u_char *sig = 0; 645 size_t blen, slen; 646 647 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 648 fatal("%s: sshbuf_new", __func__); 649 650 while (ssh_packet_remaining(ssh) > 0) { 651 sshkey_free(key); 652 key = NULL; 653 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 654 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 655 error("%s: couldn't parse key: %s", 656 __func__, ssh_err(r)); 657 goto out; 658 } 659 /* 660 * Better check that this is actually one of our hostkeys 661 * before attempting to sign anything with it. 662 */ 663 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 664 error("%s: unknown host %s key", 665 __func__, sshkey_type(key)); 666 goto out; 667 } 668 /* 669 * XXX refactor: make kex->sign just use an index rather 670 * than passing in public and private keys 671 */ 672 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 673 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 674 error("%s: can't retrieve hostkey %d", __func__, ndx); 675 goto out; 676 } 677 sshbuf_reset(sigbuf); 678 free(sig); 679 sig = NULL; 680 if ((r = sshbuf_put_cstring(sigbuf, 681 "hostkeys-prove-00 (at) openssh.com")) != 0 || 682 (r = sshbuf_put_string(sigbuf, 683 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 684 (r = sshkey_puts(key, sigbuf)) != 0 || 685 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 686 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 || 687 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 688 error("%s: couldn't prepare signature: %s", 689 __func__, ssh_err(r)); 690 goto out; 691 } 692 } 693 /* Success */ 694 *respp = resp; 695 resp = NULL; /* don't free it */ 696 success = 1; 697 out: 698 free(sig); 699 sshbuf_free(resp); 700 sshbuf_free(sigbuf); 701 sshkey_free(key); 702 return success; 703 } 704 705 static int 706 server_input_global_request(int type, u_int32_t seq, void *ctxt) 707 { 708 char *rtype; 709 int want_reply; 710 int r, success = 0, allocated_listen_port = 0; 711 struct sshbuf *resp = NULL; 712 struct passwd *pw = the_authctxt->pw; 713 714 if (pw == NULL || !the_authctxt->valid) 715 fatal("server_input_global_request: no/invalid user"); 716 717 rtype = packet_get_string(NULL); 718 want_reply = packet_get_char(); 719 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 720 721 /* -R style forwarding */ 722 if (strcmp(rtype, "tcpip-forward") == 0) { 723 struct Forward fwd; 724 725 memset(&fwd, 0, sizeof(fwd)); 726 fwd.listen_host = packet_get_string(NULL); 727 fwd.listen_port = (u_short)packet_get_int(); 728 debug("server_input_global_request: tcpip-forward listen %s port %d", 729 fwd.listen_host, fwd.listen_port); 730 731 /* check permissions */ 732 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 733 no_port_forwarding_flag || options.disable_forwarding || 734 (!want_reply && fwd.listen_port == 0) || 735 (fwd.listen_port != 0 && 736 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 737 success = 0; 738 packet_send_debug("Server has disabled port forwarding."); 739 } else { 740 /* Start listening on the port */ 741 success = channel_setup_remote_fwd_listener(&fwd, 742 &allocated_listen_port, &options.fwd_opts); 743 } 744 free(fwd.listen_host); 745 if ((resp = sshbuf_new()) == NULL) 746 fatal("%s: sshbuf_new", __func__); 747 if (allocated_listen_port != 0 && 748 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 749 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 750 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 751 struct Forward fwd; 752 753 memset(&fwd, 0, sizeof(fwd)); 754 fwd.listen_host = packet_get_string(NULL); 755 fwd.listen_port = (u_short)packet_get_int(); 756 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 757 fwd.listen_host, fwd.listen_port); 758 759 success = channel_cancel_rport_listener(&fwd); 760 free(fwd.listen_host); 761 } else if (strcmp(rtype, "streamlocal-forward (at) openssh.com") == 0) { 762 struct Forward fwd; 763 764 memset(&fwd, 0, sizeof(fwd)); 765 fwd.listen_path = packet_get_string(NULL); 766 debug("server_input_global_request: streamlocal-forward listen path %s", 767 fwd.listen_path); 768 769 /* check permissions */ 770 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 771 || no_port_forwarding_flag || options.disable_forwarding || 772 (pw->pw_uid != 0 && !use_privsep)) { 773 success = 0; 774 packet_send_debug("Server has disabled " 775 "streamlocal forwarding."); 776 } else { 777 /* Start listening on the socket */ 778 success = channel_setup_remote_fwd_listener( 779 &fwd, NULL, &options.fwd_opts); 780 } 781 free(fwd.listen_path); 782 } else if (strcmp(rtype, "cancel-streamlocal-forward (at) openssh.com") == 0) { 783 struct Forward fwd; 784 785 memset(&fwd, 0, sizeof(fwd)); 786 fwd.listen_path = packet_get_string(NULL); 787 debug("%s: cancel-streamlocal-forward path %s", __func__, 788 fwd.listen_path); 789 790 success = channel_cancel_rport_listener(&fwd); 791 free(fwd.listen_path); 792 } else if (strcmp(rtype, "no-more-sessions (at) openssh.com") == 0) { 793 no_more_sessions = 1; 794 success = 1; 795 } else if (strcmp(rtype, "hostkeys-prove-00 (at) openssh.com") == 0) { 796 success = server_input_hostkeys_prove(&resp); 797 } 798 if (want_reply) { 799 packet_start(success ? 800 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 801 if (success && resp != NULL) 802 ssh_packet_put_raw(active_state, sshbuf_ptr(resp), 803 sshbuf_len(resp)); 804 packet_send(); 805 packet_write_wait(); 806 } 807 free(rtype); 808 sshbuf_free(resp); 809 return 0; 810 } 811 812 static int 813 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 814 { 815 Channel *c; 816 int id, reply, success = 0; 817 char *rtype; 818 819 id = packet_get_int(); 820 rtype = packet_get_string(NULL); 821 reply = packet_get_char(); 822 823 debug("server_input_channel_req: channel %d request %s reply %d", 824 id, rtype, reply); 825 826 if ((c = channel_lookup(id)) == NULL) 827 packet_disconnect("server_input_channel_req: " 828 "unknown channel %d", id); 829 if (!strcmp(rtype, "eow (at) openssh.com")) { 830 packet_check_eom(); 831 chan_rcvd_eow(c); 832 } else if ((c->type == SSH_CHANNEL_LARVAL || 833 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 834 success = session_input_channel_req(c, rtype); 835 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 836 packet_start(success ? 837 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 838 packet_put_int(c->remote_id); 839 packet_send(); 840 } 841 free(rtype); 842 return 0; 843 } 844 845 static void 846 server_init_dispatch(void) 847 { 848 debug("server_init_dispatch"); 849 dispatch_init(&dispatch_protocol_error); 850 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 851 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 852 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 853 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 854 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 855 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 856 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 857 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 858 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 859 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 860 /* client_alive */ 861 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 862 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 863 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 864 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 865 /* rekeying */ 866 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 867 } 868
