1 /* $OpenBSD: serverloop.c,v 1.198 2017/09/12 06:35:32 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@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 <sys/types.h> 39 #include <sys/wait.h> 40 #include <sys/socket.h> 41 #include <sys/time.h> 42 #include <sys/queue.h> 43 44 #include <netinet/in.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <pwd.h> 49 #include <signal.h> 50 #include <string.h> 51 #include <termios.h> 52 #include <unistd.h> 53 #include <stdarg.h> 54 55 #include "xmalloc.h" 56 #include "packet.h" 57 #include "buffer.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "servconf.h" 61 #include "canohost.h" 62 #include "sshpty.h" 63 #include "channels.h" 64 #include "compat.h" 65 #include "ssh2.h" 66 #include "key.h" 67 #include "cipher.h" 68 #include "kex.h" 69 #include "hostfile.h" 70 #include "auth.h" 71 #include "session.h" 72 #include "dispatch.h" 73 #include "auth-options.h" 74 #include "serverloop.h" 75 #include "ssherr.h" 76 77 extern ServerOptions options; 78 79 /* XXX */ 80 extern Authctxt *the_authctxt; 81 extern int use_privsep; 82 83 static int no_more_sessions = 0; /* Disallow further sessions. */ 84 85 /* 86 * This SIGCHLD kludge is used to detect when the child exits. The server 87 * will exit after that, as soon as forwarded connections have terminated. 88 */ 89 90 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 91 92 /* Cleanup on signals (!use_privsep case only) */ 93 static volatile sig_atomic_t received_sigterm = 0; 94 95 /* prototypes */ 96 static void server_init_dispatch(void); 97 98 /* 99 * we write to this pipe if a SIGCHLD is caught in order to avoid 100 * the race between select() and child_terminated 101 */ 102 static int notify_pipe[2]; 103 static void 104 notify_setup(void) 105 { 106 if (pipe(notify_pipe) < 0) { 107 error("pipe(notify_pipe) failed %s", strerror(errno)); 108 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 109 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 110 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 111 close(notify_pipe[0]); 112 close(notify_pipe[1]); 113 } else { 114 set_nonblock(notify_pipe[0]); 115 set_nonblock(notify_pipe[1]); 116 return; 117 } 118 notify_pipe[0] = -1; /* read end */ 119 notify_pipe[1] = -1; /* write end */ 120 } 121 static void 122 notify_parent(void) 123 { 124 if (notify_pipe[1] != -1) 125 (void)write(notify_pipe[1], "", 1); 126 } 127 static void 128 notify_prepare(fd_set *readset) 129 { 130 if (notify_pipe[0] != -1) 131 FD_SET(notify_pipe[0], readset); 132 } 133 static void 134 notify_done(fd_set *readset) 135 { 136 char c; 137 138 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 139 while (read(notify_pipe[0], &c, 1) != -1) 140 debug2("notify_done: reading"); 141 } 142 143 /*ARGSUSED*/ 144 static void 145 sigchld_handler(int sig) 146 { 147 int save_errno = errno; 148 child_terminated = 1; 149 signal(SIGCHLD, sigchld_handler); 150 notify_parent(); 151 errno = save_errno; 152 } 153 154 /*ARGSUSED*/ 155 static void 156 sigterm_handler(int sig) 157 { 158 received_sigterm = sig; 159 } 160 161 static void 162 client_alive_check(struct ssh *ssh) 163 { 164 int channel_id; 165 166 /* timeout, check to see how many we have had */ 167 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 168 logit("Timeout, client not responding."); 169 cleanup_exit(255); 170 } 171 172 /* 173 * send a bogus global/channel request with "wantreply", 174 * we should get back a failure 175 */ 176 if ((channel_id = channel_find_open(ssh)) == -1) { 177 packet_start(SSH2_MSG_GLOBAL_REQUEST); 178 packet_put_cstring("keepalive@openssh.com"); 179 packet_put_char(1); /* boolean: want reply */ 180 } else { 181 channel_request_start(ssh, channel_id, 182 "keepalive@openssh.com", 1); 183 } 184 packet_send(); 185 } 186 187 /* 188 * Sleep in select() until we can do something. This will initialize the 189 * select masks. Upon return, the masks will indicate which descriptors 190 * have data or can accept data. Optionally, a maximum time can be specified 191 * for the duration of the wait (0 = infinite). 192 */ 193 static void 194 wait_until_can_do_something(struct ssh *ssh, 195 int connection_in, int connection_out, 196 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 197 u_int *nallocp, u_int64_t max_time_ms) 198 { 199 struct timeval tv, *tvp; 200 int ret; 201 time_t minwait_secs = 0; 202 int client_alive_scheduled = 0; 203 static time_t last_client_time; 204 205 /* Allocate and update select() masks for channel descriptors. */ 206 channel_prepare_select(ssh, readsetp, writesetp, maxfdp, 207 nallocp, &minwait_secs); 208 209 /* XXX need proper deadline system for rekey/client alive */ 210 if (minwait_secs != 0) 211 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 212 213 /* 214 * if using client_alive, set the max timeout accordingly, 215 * and indicate that this particular timeout was for client 216 * alive by setting the client_alive_scheduled flag. 217 * 218 * this could be randomized somewhat to make traffic 219 * analysis more difficult, but we're not doing it yet. 220 */ 221 if (options.client_alive_interval) { 222 uint64_t keepalive_ms = 223 (uint64_t)options.client_alive_interval * 1000; 224 225 client_alive_scheduled = 1; 226 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 227 max_time_ms = keepalive_ms; 228 } 229 230 #if 0 231 /* wrong: bad condition XXX */ 232 if (channel_not_very_much_buffered_data()) 233 #endif 234 FD_SET(connection_in, *readsetp); 235 notify_prepare(*readsetp); 236 237 /* 238 * If we have buffered packet data going to the client, mark that 239 * descriptor. 240 */ 241 if (packet_have_data_to_write()) 242 FD_SET(connection_out, *writesetp); 243 244 /* 245 * If child has terminated and there is enough buffer space to read 246 * from it, then read as much as is available and exit. 247 */ 248 if (child_terminated && packet_not_very_much_data_to_write()) 249 if (max_time_ms == 0 || client_alive_scheduled) 250 max_time_ms = 100; 251 252 if (max_time_ms == 0) 253 tvp = NULL; 254 else { 255 tv.tv_sec = max_time_ms / 1000; 256 tv.tv_usec = 1000 * (max_time_ms % 1000); 257 tvp = &tv; 258 } 259 260 /* Wait for something to happen, or the timeout to expire. */ 261 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 262 263 if (ret == -1) { 264 memset(*readsetp, 0, *nallocp); 265 memset(*writesetp, 0, *nallocp); 266 if (errno != EINTR) 267 error("select: %.100s", strerror(errno)); 268 } else if (client_alive_scheduled) { 269 time_t now = monotime(); 270 271 if (ret == 0) { /* timeout */ 272 client_alive_check(ssh); 273 } else if (FD_ISSET(connection_in, *readsetp)) { 274 last_client_time = now; 275 } else if (last_client_time != 0 && last_client_time + 276 options.client_alive_interval <= now) { 277 client_alive_check(ssh); 278 last_client_time = now; 279 } 280 } 281 282 notify_done(*readsetp); 283 } 284 285 /* 286 * Processes input from the client and the program. Input data is stored 287 * in buffers and processed later. 288 */ 289 static int 290 process_input(struct ssh *ssh, fd_set *readset, int connection_in) 291 { 292 int len; 293 char buf[16384]; 294 295 /* Read and buffer any input data from the client. */ 296 if (FD_ISSET(connection_in, readset)) { 297 len = read(connection_in, buf, sizeof(buf)); 298 if (len == 0) { 299 verbose("Connection closed by %.100s port %d", 300 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 301 return -1; 302 } else if (len < 0) { 303 if (errno != EINTR && errno != EAGAIN) { 304 verbose("Read error from remote host " 305 "%.100s port %d: %.100s", 306 ssh_remote_ipaddr(ssh), 307 ssh_remote_port(ssh), strerror(errno)); 308 cleanup_exit(255); 309 } 310 } else { 311 /* Buffer any received data. */ 312 packet_process_incoming(buf, len); 313 } 314 } 315 return 0; 316 } 317 318 /* 319 * Sends data from internal buffers to client program stdin. 320 */ 321 static void 322 process_output(fd_set *writeset, int connection_out) 323 { 324 /* Send any buffered packet data to the client. */ 325 if (FD_ISSET(connection_out, writeset)) 326 packet_write_poll(); 327 } 328 329 static void 330 process_buffered_input_packets(struct ssh *ssh) 331 { 332 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); 333 } 334 335 static void 336 collect_children(struct ssh *ssh) 337 { 338 pid_t pid; 339 sigset_t oset, nset; 340 int status; 341 342 /* block SIGCHLD while we check for dead children */ 343 sigemptyset(&nset); 344 sigaddset(&nset, SIGCHLD); 345 sigprocmask(SIG_BLOCK, &nset, &oset); 346 if (child_terminated) { 347 debug("Received SIGCHLD."); 348 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 349 (pid < 0 && errno == EINTR)) 350 if (pid > 0) 351 session_close_by_pid(ssh, pid, status); 352 child_terminated = 0; 353 } 354 sigprocmask(SIG_SETMASK, &oset, NULL); 355 } 356 357 void 358 server_loop2(struct ssh *ssh, Authctxt *authctxt) 359 { 360 fd_set *readset = NULL, *writeset = NULL; 361 int max_fd; 362 u_int nalloc = 0, connection_in, connection_out; 363 u_int64_t rekey_timeout_ms = 0; 364 365 debug("Entering interactive session for SSH2."); 366 367 signal(SIGCHLD, sigchld_handler); 368 child_terminated = 0; 369 connection_in = packet_get_connection_in(); 370 connection_out = packet_get_connection_out(); 371 372 if (!use_privsep) { 373 signal(SIGTERM, sigterm_handler); 374 signal(SIGINT, sigterm_handler); 375 signal(SIGQUIT, sigterm_handler); 376 } 377 378 notify_setup(); 379 380 max_fd = MAXIMUM(connection_in, connection_out); 381 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 382 383 server_init_dispatch(); 384 385 for (;;) { 386 process_buffered_input_packets(ssh); 387 388 if (!ssh_packet_is_rekeying(ssh) && 389 packet_not_very_much_data_to_write()) 390 channel_output_poll(ssh); 391 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) 392 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 393 else 394 rekey_timeout_ms = 0; 395 396 wait_until_can_do_something(ssh, connection_in, connection_out, 397 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 398 399 if (received_sigterm) { 400 logit("Exiting on signal %d", (int)received_sigterm); 401 /* Clean up sessions, utmp, etc. */ 402 cleanup_exit(255); 403 } 404 405 collect_children(ssh); 406 if (!ssh_packet_is_rekeying(ssh)) 407 channel_after_select(ssh, readset, writeset); 408 if (process_input(ssh, readset, connection_in) < 0) 409 break; 410 process_output(writeset, connection_out); 411 } 412 collect_children(ssh); 413 414 free(readset); 415 free(writeset); 416 417 /* free all channels, no more reads and writes */ 418 channel_free_all(ssh); 419 420 /* free remaining sessions, e.g. remove wtmp entries */ 421 session_destroy_all(ssh, NULL); 422 } 423 424 static int 425 server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) 426 { 427 debug("Got %d/%u for keepalive", type, seq); 428 /* 429 * reset timeout, since we got a sane answer from the client. 430 * even if this was generated by something other than 431 * the bogus CHANNEL_REQUEST we send for keepalives. 432 */ 433 packet_set_alive_timeouts(0); 434 return 0; 435 } 436 437 static Channel * 438 server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) 439 { 440 Channel *c = NULL; 441 char *target, *originator; 442 u_short target_port, originator_port; 443 444 target = packet_get_string(NULL); 445 target_port = packet_get_int(); 446 originator = packet_get_string(NULL); 447 originator_port = packet_get_int(); 448 packet_check_eom(); 449 450 debug("server_request_direct_tcpip: originator %s port %d, target %s " 451 "port %d", originator, originator_port, target, target_port); 452 453 /* XXX fine grained permissions */ 454 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 455 !no_port_forwarding_flag && !options.disable_forwarding) { 456 c = channel_connect_to_port(ssh, target, target_port, 457 "direct-tcpip", "direct-tcpip", reason, errmsg); 458 } else { 459 logit("refused local port forward: " 460 "originator %s port %d, target %s port %d", 461 originator, originator_port, target, target_port); 462 if (reason != NULL) 463 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 464 } 465 466 free(originator); 467 free(target); 468 469 return c; 470 } 471 472 static Channel * 473 server_request_direct_streamlocal(struct ssh *ssh) 474 { 475 Channel *c = NULL; 476 char *target, *originator; 477 u_short originator_port; 478 struct passwd *pw = the_authctxt->pw; 479 480 if (pw == NULL || !the_authctxt->valid) 481 fatal("server_input_global_request: no/invalid user"); 482 483 target = packet_get_string(NULL); 484 originator = packet_get_string(NULL); 485 originator_port = packet_get_int(); 486 packet_check_eom(); 487 488 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 489 originator, originator_port, target); 490 491 /* XXX fine grained permissions */ 492 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 493 !no_port_forwarding_flag && !options.disable_forwarding && 494 (pw->pw_uid == 0 || use_privsep)) { 495 c = channel_connect_to_path(ssh, target, 496 "direct-streamlocal@openssh.com", "direct-streamlocal"); 497 } else { 498 logit("refused streamlocal port forward: " 499 "originator %s port %d, target %s", 500 originator, originator_port, target); 501 } 502 503 free(originator); 504 free(target); 505 506 return c; 507 } 508 509 static Channel * 510 server_request_tun(struct ssh *ssh) 511 { 512 Channel *c = NULL; 513 int mode, tun; 514 int sock; 515 516 mode = packet_get_int(); 517 switch (mode) { 518 case SSH_TUNMODE_POINTOPOINT: 519 case SSH_TUNMODE_ETHERNET: 520 break; 521 default: 522 packet_send_debug("Unsupported tunnel device mode."); 523 return NULL; 524 } 525 if ((options.permit_tun & mode) == 0) { 526 packet_send_debug("Server has rejected tunnel device " 527 "forwarding"); 528 return NULL; 529 } 530 531 tun = packet_get_int(); 532 if (forced_tun_device != -1) { 533 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 534 goto done; 535 tun = forced_tun_device; 536 } 537 sock = tun_open(tun, mode); 538 if (sock < 0) 539 goto done; 540 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, 541 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 542 c->datagram = 1; 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(struct ssh *ssh) 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(ssh, "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(ssh, c); 575 return NULL; 576 } 577 channel_register_cleanup(ssh, 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, struct ssh *ssh) 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(ssh); 600 } else if (strcmp(ctype, "direct-tcpip") == 0) { 601 c = server_request_direct_tcpip(ssh, &reason, &errmsg); 602 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 603 c = server_request_direct_streamlocal(ssh); 604 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 605 c = server_request_tun(ssh); 606 } 607 if (c != NULL) { 608 debug("server_input_channel_open: confirm %s", ctype); 609 c->remote_id = rchan; 610 c->have_remote_id = 1; 611 c->remote_window = rwindow; 612 c->remote_maxpacket = rmaxpack; 613 if (c->type != SSH_CHANNEL_CONNECTING) { 614 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 615 packet_put_int(c->remote_id); 616 packet_put_int(c->self); 617 packet_put_int(c->local_window); 618 packet_put_int(c->local_maxpacket); 619 packet_send(); 620 } 621 } else { 622 debug("server_input_channel_open: failure %s", ctype); 623 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 624 packet_put_int(rchan); 625 packet_put_int(reason); 626 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 627 packet_put_cstring(errmsg ? errmsg : "open failed"); 628 packet_put_cstring(""); 629 } 630 packet_send(); 631 } 632 free(ctype); 633 return 0; 634 } 635 636 static int 637 server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) 638 { 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@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, struct ssh *ssh) 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(ssh, &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(ssh, &fwd); 760 free(fwd.listen_host); 761 } else if (strcmp(rtype, "streamlocal-forward@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(ssh, 779 &fwd, NULL, &options.fwd_opts); 780 } 781 free(fwd.listen_path); 782 } else if (strcmp(rtype, "cancel-streamlocal-forward@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(ssh, &fwd); 791 free(fwd.listen_path); 792 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 793 no_more_sessions = 1; 794 success = 1; 795 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 796 success = server_input_hostkeys_prove(ssh, &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(ssh, 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, struct ssh *ssh) 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(ssh, id)) == NULL) 827 packet_disconnect("server_input_channel_req: " 828 "unknown channel %d", id); 829 if (!strcmp(rtype, "eow@openssh.com")) { 830 packet_check_eom(); 831 chan_rcvd_eow(ssh, 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(ssh, c, rtype); 835 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 836 if (!c->have_remote_id) 837 fatal("%s: channel %d: no remote_id", 838 __func__, c->self); 839 packet_start(success ? 840 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 841 packet_put_int(c->remote_id); 842 packet_send(); 843 } 844 free(rtype); 845 return 0; 846 } 847 848 static void 849 server_init_dispatch(void) 850 { 851 debug("server_init_dispatch"); 852 dispatch_init(&dispatch_protocol_error); 853 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 854 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 855 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 856 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 857 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 858 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 859 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 860 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 861 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 862 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 863 /* client_alive */ 864 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 865 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 866 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 867 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 868 /* rekeying */ 869 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 870 } 871