1 /* $OpenBSD: serverloop.c,v 1.199 2017/10/23 05:08:00 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 /* requested tunnel forwarding interface(s), shared with session.c */ 99 char *tun_fwd_ifnames = NULL; 100 101 /* 102 * we write to this pipe if a SIGCHLD is caught in order to avoid 103 * the race between select() and child_terminated 104 */ 105 static int notify_pipe[2]; 106 static void 107 notify_setup(void) 108 { 109 if (pipe(notify_pipe) < 0) { 110 error("pipe(notify_pipe) failed %s", strerror(errno)); 111 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 112 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 113 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 114 close(notify_pipe[0]); 115 close(notify_pipe[1]); 116 } else { 117 set_nonblock(notify_pipe[0]); 118 set_nonblock(notify_pipe[1]); 119 return; 120 } 121 notify_pipe[0] = -1; /* read end */ 122 notify_pipe[1] = -1; /* write end */ 123 } 124 static void 125 notify_parent(void) 126 { 127 if (notify_pipe[1] != -1) 128 (void)write(notify_pipe[1], "", 1); 129 } 130 static void 131 notify_prepare(fd_set *readset) 132 { 133 if (notify_pipe[0] != -1) 134 FD_SET(notify_pipe[0], readset); 135 } 136 static void 137 notify_done(fd_set *readset) 138 { 139 char c; 140 141 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 142 while (read(notify_pipe[0], &c, 1) != -1) 143 debug2("notify_done: reading"); 144 } 145 146 /*ARGSUSED*/ 147 static void 148 sigchld_handler(int sig) 149 { 150 int save_errno = errno; 151 child_terminated = 1; 152 signal(SIGCHLD, sigchld_handler); 153 notify_parent(); 154 errno = save_errno; 155 } 156 157 /*ARGSUSED*/ 158 static void 159 sigterm_handler(int sig) 160 { 161 received_sigterm = sig; 162 } 163 164 static void 165 client_alive_check(struct ssh *ssh) 166 { 167 int channel_id; 168 169 /* timeout, check to see how many we have had */ 170 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 171 logit("Timeout, client not responding."); 172 cleanup_exit(255); 173 } 174 175 /* 176 * send a bogus global/channel request with "wantreply", 177 * we should get back a failure 178 */ 179 if ((channel_id = channel_find_open(ssh)) == -1) { 180 packet_start(SSH2_MSG_GLOBAL_REQUEST); 181 packet_put_cstring("keepalive@openssh.com"); 182 packet_put_char(1); /* boolean: want reply */ 183 } else { 184 channel_request_start(ssh, channel_id, 185 "keepalive@openssh.com", 1); 186 } 187 packet_send(); 188 } 189 190 /* 191 * Sleep in select() until we can do something. This will initialize the 192 * select masks. Upon return, the masks will indicate which descriptors 193 * have data or can accept data. Optionally, a maximum time can be specified 194 * for the duration of the wait (0 = infinite). 195 */ 196 static void 197 wait_until_can_do_something(struct ssh *ssh, 198 int connection_in, int connection_out, 199 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 200 u_int *nallocp, u_int64_t max_time_ms) 201 { 202 struct timeval tv, *tvp; 203 int ret; 204 time_t minwait_secs = 0; 205 int client_alive_scheduled = 0; 206 static time_t last_client_time; 207 208 /* Allocate and update select() masks for channel descriptors. */ 209 channel_prepare_select(ssh, readsetp, writesetp, maxfdp, 210 nallocp, &minwait_secs); 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 (client_alive_scheduled) { 272 time_t now = monotime(); 273 274 if (ret == 0) { /* timeout */ 275 client_alive_check(ssh); 276 } else if (FD_ISSET(connection_in, *readsetp)) { 277 last_client_time = now; 278 } else if (last_client_time != 0 && last_client_time + 279 options.client_alive_interval <= now) { 280 client_alive_check(ssh); 281 last_client_time = now; 282 } 283 } 284 285 notify_done(*readsetp); 286 } 287 288 /* 289 * Processes input from the client and the program. Input data is stored 290 * in buffers and processed later. 291 */ 292 static int 293 process_input(struct ssh *ssh, fd_set *readset, int connection_in) 294 { 295 int len; 296 char buf[16384]; 297 298 /* Read and buffer any input data from the client. */ 299 if (FD_ISSET(connection_in, readset)) { 300 len = read(connection_in, buf, sizeof(buf)); 301 if (len == 0) { 302 verbose("Connection closed by %.100s port %d", 303 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 304 return -1; 305 } else if (len < 0) { 306 if (errno != EINTR && errno != EAGAIN) { 307 verbose("Read error from remote host " 308 "%.100s port %d: %.100s", 309 ssh_remote_ipaddr(ssh), 310 ssh_remote_port(ssh), strerror(errno)); 311 cleanup_exit(255); 312 } 313 } else { 314 /* Buffer any received data. */ 315 packet_process_incoming(buf, len); 316 } 317 } 318 return 0; 319 } 320 321 /* 322 * Sends data from internal buffers to client program stdin. 323 */ 324 static void 325 process_output(fd_set *writeset, int connection_out) 326 { 327 /* Send any buffered packet data to the client. */ 328 if (FD_ISSET(connection_out, writeset)) 329 packet_write_poll(); 330 } 331 332 static void 333 process_buffered_input_packets(struct ssh *ssh) 334 { 335 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); 336 } 337 338 static void 339 collect_children(struct ssh *ssh) 340 { 341 pid_t pid; 342 sigset_t oset, nset; 343 int status; 344 345 /* block SIGCHLD while we check for dead children */ 346 sigemptyset(&nset); 347 sigaddset(&nset, SIGCHLD); 348 sigprocmask(SIG_BLOCK, &nset, &oset); 349 if (child_terminated) { 350 debug("Received SIGCHLD."); 351 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 352 (pid < 0 && errno == EINTR)) 353 if (pid > 0) 354 session_close_by_pid(ssh, pid, status); 355 child_terminated = 0; 356 } 357 sigprocmask(SIG_SETMASK, &oset, NULL); 358 } 359 360 void 361 server_loop2(struct ssh *ssh, Authctxt *authctxt) 362 { 363 fd_set *readset = NULL, *writeset = NULL; 364 int max_fd; 365 u_int nalloc = 0, connection_in, connection_out; 366 u_int64_t rekey_timeout_ms = 0; 367 368 debug("Entering interactive session for SSH2."); 369 370 signal(SIGCHLD, sigchld_handler); 371 child_terminated = 0; 372 connection_in = packet_get_connection_in(); 373 connection_out = packet_get_connection_out(); 374 375 if (!use_privsep) { 376 signal(SIGTERM, sigterm_handler); 377 signal(SIGINT, sigterm_handler); 378 signal(SIGQUIT, sigterm_handler); 379 } 380 381 notify_setup(); 382 383 max_fd = MAXIMUM(connection_in, connection_out); 384 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 385 386 server_init_dispatch(); 387 388 for (;;) { 389 process_buffered_input_packets(ssh); 390 391 if (!ssh_packet_is_rekeying(ssh) && 392 packet_not_very_much_data_to_write()) 393 channel_output_poll(ssh); 394 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) 395 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 396 else 397 rekey_timeout_ms = 0; 398 399 wait_until_can_do_something(ssh, connection_in, connection_out, 400 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 401 402 if (received_sigterm) { 403 logit("Exiting on signal %d", (int)received_sigterm); 404 /* Clean up sessions, utmp, etc. */ 405 cleanup_exit(255); 406 } 407 408 collect_children(ssh); 409 if (!ssh_packet_is_rekeying(ssh)) 410 channel_after_select(ssh, readset, writeset); 411 if (process_input(ssh, readset, connection_in) < 0) 412 break; 413 process_output(writeset, connection_out); 414 } 415 collect_children(ssh); 416 417 free(readset); 418 free(writeset); 419 420 /* free all channels, no more reads and writes */ 421 channel_free_all(ssh); 422 423 /* free remaining sessions, e.g. remove wtmp entries */ 424 session_destroy_all(ssh, NULL); 425 } 426 427 static int 428 server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) 429 { 430 debug("Got %d/%u for keepalive", type, seq); 431 /* 432 * reset timeout, since we got a sane answer from the client. 433 * even if this was generated by something other than 434 * the bogus CHANNEL_REQUEST we send for keepalives. 435 */ 436 packet_set_alive_timeouts(0); 437 return 0; 438 } 439 440 static Channel * 441 server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) 442 { 443 Channel *c = NULL; 444 char *target, *originator; 445 u_short target_port, originator_port; 446 447 target = packet_get_string(NULL); 448 target_port = packet_get_int(); 449 originator = packet_get_string(NULL); 450 originator_port = packet_get_int(); 451 packet_check_eom(); 452 453 debug("server_request_direct_tcpip: originator %s port %d, target %s " 454 "port %d", originator, originator_port, target, target_port); 455 456 /* XXX fine grained permissions */ 457 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 458 !no_port_forwarding_flag && !options.disable_forwarding) { 459 c = channel_connect_to_port(ssh, target, target_port, 460 "direct-tcpip", "direct-tcpip", reason, errmsg); 461 } else { 462 logit("refused local port forward: " 463 "originator %s port %d, target %s port %d", 464 originator, originator_port, target, target_port); 465 if (reason != NULL) 466 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 467 } 468 469 free(originator); 470 free(target); 471 472 return c; 473 } 474 475 static Channel * 476 server_request_direct_streamlocal(struct ssh *ssh) 477 { 478 Channel *c = NULL; 479 char *target, *originator; 480 u_short originator_port; 481 struct passwd *pw = the_authctxt->pw; 482 483 if (pw == NULL || !the_authctxt->valid) 484 fatal("server_input_global_request: no/invalid user"); 485 486 target = packet_get_string(NULL); 487 originator = packet_get_string(NULL); 488 originator_port = packet_get_int(); 489 packet_check_eom(); 490 491 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 492 originator, originator_port, target); 493 494 /* XXX fine grained permissions */ 495 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 496 !no_port_forwarding_flag && !options.disable_forwarding && 497 (pw->pw_uid == 0 || use_privsep)) { 498 c = channel_connect_to_path(ssh, target, 499 "direct-streamlocal@openssh.com", "direct-streamlocal"); 500 } else { 501 logit("refused streamlocal port forward: " 502 "originator %s port %d, target %s", 503 originator, originator_port, target); 504 } 505 506 free(originator); 507 free(target); 508 509 return c; 510 } 511 512 static Channel * 513 server_request_tun(struct ssh *ssh) 514 { 515 Channel *c = NULL; 516 int mode, tun; 517 int sock; 518 char *tmp, *ifname = NULL; 519 520 mode = packet_get_int(); 521 switch (mode) { 522 case SSH_TUNMODE_POINTOPOINT: 523 case SSH_TUNMODE_ETHERNET: 524 break; 525 default: 526 packet_send_debug("Unsupported tunnel device mode."); 527 return NULL; 528 } 529 if ((options.permit_tun & mode) == 0) { 530 packet_send_debug("Server has rejected tunnel device " 531 "forwarding"); 532 return NULL; 533 } 534 535 tun = packet_get_int(); 536 if (forced_tun_device != -1) { 537 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 538 goto done; 539 tun = forced_tun_device; 540 } 541 sock = tun_open(tun, mode, &ifname); 542 if (sock < 0) 543 goto done; 544 debug("Tunnel forwarding using interface %s", ifname); 545 546 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, 547 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 548 c->datagram = 1; 549 550 /* 551 * Update the list of names exposed to the session 552 * XXX remove these if the tunnels are closed (won't matter 553 * much if they are already in the environment though) 554 */ 555 tmp = tun_fwd_ifnames; 556 xasprintf(&tun_fwd_ifnames, "%s%s%s", 557 tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames, 558 tun_fwd_ifnames == NULL ? "" : ",", 559 ifname); 560 free(tmp); 561 free(ifname); 562 563 done: 564 if (c == NULL) 565 packet_send_debug("Failed to open the tunnel device."); 566 return c; 567 } 568 569 static Channel * 570 server_request_session(struct ssh *ssh) 571 { 572 Channel *c; 573 574 debug("input_session_request"); 575 packet_check_eom(); 576 577 if (no_more_sessions) { 578 packet_disconnect("Possible attack: attempt to open a session " 579 "after additional sessions disabled"); 580 } 581 582 /* 583 * A server session has no fd to read or write until a 584 * CHANNEL_REQUEST for a shell is made, so we set the type to 585 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 586 * CHANNEL_REQUEST messages is registered. 587 */ 588 c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL, 589 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 590 0, "server-session", 1); 591 if (session_open(the_authctxt, c->self) != 1) { 592 debug("session open failed, free channel %d", c->self); 593 channel_free(ssh, c); 594 return NULL; 595 } 596 channel_register_cleanup(ssh, c->self, session_close_by_channel, 0); 597 return c; 598 } 599 600 static int 601 server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 602 { 603 Channel *c = NULL; 604 char *ctype; 605 const char *errmsg = NULL; 606 int rchan, reason = SSH2_OPEN_CONNECT_FAILED; 607 u_int rmaxpack, rwindow, len; 608 609 ctype = packet_get_string(&len); 610 rchan = packet_get_int(); 611 rwindow = packet_get_int(); 612 rmaxpack = packet_get_int(); 613 614 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 615 ctype, rchan, rwindow, rmaxpack); 616 617 if (strcmp(ctype, "session") == 0) { 618 c = server_request_session(ssh); 619 } else if (strcmp(ctype, "direct-tcpip") == 0) { 620 c = server_request_direct_tcpip(ssh, &reason, &errmsg); 621 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 622 c = server_request_direct_streamlocal(ssh); 623 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 624 c = server_request_tun(ssh); 625 } 626 if (c != NULL) { 627 debug("server_input_channel_open: confirm %s", ctype); 628 c->remote_id = rchan; 629 c->have_remote_id = 1; 630 c->remote_window = rwindow; 631 c->remote_maxpacket = rmaxpack; 632 if (c->type != SSH_CHANNEL_CONNECTING) { 633 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 634 packet_put_int(c->remote_id); 635 packet_put_int(c->self); 636 packet_put_int(c->local_window); 637 packet_put_int(c->local_maxpacket); 638 packet_send(); 639 } 640 } else { 641 debug("server_input_channel_open: failure %s", ctype); 642 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 643 packet_put_int(rchan); 644 packet_put_int(reason); 645 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 646 packet_put_cstring(errmsg ? errmsg : "open failed"); 647 packet_put_cstring(""); 648 } 649 packet_send(); 650 } 651 free(ctype); 652 return 0; 653 } 654 655 static int 656 server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) 657 { 658 struct sshbuf *resp = NULL; 659 struct sshbuf *sigbuf = NULL; 660 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 661 int r, ndx, success = 0; 662 const u_char *blob; 663 u_char *sig = 0; 664 size_t blen, slen; 665 666 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 667 fatal("%s: sshbuf_new", __func__); 668 669 while (ssh_packet_remaining(ssh) > 0) { 670 sshkey_free(key); 671 key = NULL; 672 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 673 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 674 error("%s: couldn't parse key: %s", 675 __func__, ssh_err(r)); 676 goto out; 677 } 678 /* 679 * Better check that this is actually one of our hostkeys 680 * before attempting to sign anything with it. 681 */ 682 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 683 error("%s: unknown host %s key", 684 __func__, sshkey_type(key)); 685 goto out; 686 } 687 /* 688 * XXX refactor: make kex->sign just use an index rather 689 * than passing in public and private keys 690 */ 691 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 692 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 693 error("%s: can't retrieve hostkey %d", __func__, ndx); 694 goto out; 695 } 696 sshbuf_reset(sigbuf); 697 free(sig); 698 sig = NULL; 699 if ((r = sshbuf_put_cstring(sigbuf, 700 "hostkeys-prove-00@openssh.com")) != 0 || 701 (r = sshbuf_put_string(sigbuf, 702 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 703 (r = sshkey_puts(key, sigbuf)) != 0 || 704 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 705 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 || 706 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 707 error("%s: couldn't prepare signature: %s", 708 __func__, ssh_err(r)); 709 goto out; 710 } 711 } 712 /* Success */ 713 *respp = resp; 714 resp = NULL; /* don't free it */ 715 success = 1; 716 out: 717 free(sig); 718 sshbuf_free(resp); 719 sshbuf_free(sigbuf); 720 sshkey_free(key); 721 return success; 722 } 723 724 static int 725 server_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 726 { 727 char *rtype; 728 int want_reply; 729 int r, success = 0, allocated_listen_port = 0; 730 struct sshbuf *resp = NULL; 731 struct passwd *pw = the_authctxt->pw; 732 733 if (pw == NULL || !the_authctxt->valid) 734 fatal("server_input_global_request: no/invalid user"); 735 736 rtype = packet_get_string(NULL); 737 want_reply = packet_get_char(); 738 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 739 740 /* -R style forwarding */ 741 if (strcmp(rtype, "tcpip-forward") == 0) { 742 struct Forward fwd; 743 744 memset(&fwd, 0, sizeof(fwd)); 745 fwd.listen_host = packet_get_string(NULL); 746 fwd.listen_port = (u_short)packet_get_int(); 747 debug("server_input_global_request: tcpip-forward listen %s port %d", 748 fwd.listen_host, fwd.listen_port); 749 750 /* check permissions */ 751 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 752 no_port_forwarding_flag || options.disable_forwarding || 753 (!want_reply && fwd.listen_port == 0) || 754 (fwd.listen_port != 0 && 755 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 756 success = 0; 757 packet_send_debug("Server has disabled port forwarding."); 758 } else { 759 /* Start listening on the port */ 760 success = channel_setup_remote_fwd_listener(ssh, &fwd, 761 &allocated_listen_port, &options.fwd_opts); 762 } 763 free(fwd.listen_host); 764 if ((resp = sshbuf_new()) == NULL) 765 fatal("%s: sshbuf_new", __func__); 766 if (allocated_listen_port != 0 && 767 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 768 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 769 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 770 struct Forward fwd; 771 772 memset(&fwd, 0, sizeof(fwd)); 773 fwd.listen_host = packet_get_string(NULL); 774 fwd.listen_port = (u_short)packet_get_int(); 775 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 776 fwd.listen_host, fwd.listen_port); 777 778 success = channel_cancel_rport_listener(ssh, &fwd); 779 free(fwd.listen_host); 780 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 781 struct Forward fwd; 782 783 memset(&fwd, 0, sizeof(fwd)); 784 fwd.listen_path = packet_get_string(NULL); 785 debug("server_input_global_request: streamlocal-forward listen path %s", 786 fwd.listen_path); 787 788 /* check permissions */ 789 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 790 || no_port_forwarding_flag || options.disable_forwarding || 791 (pw->pw_uid != 0 && !use_privsep)) { 792 success = 0; 793 packet_send_debug("Server has disabled " 794 "streamlocal forwarding."); 795 } else { 796 /* Start listening on the socket */ 797 success = channel_setup_remote_fwd_listener(ssh, 798 &fwd, NULL, &options.fwd_opts); 799 } 800 free(fwd.listen_path); 801 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 802 struct Forward fwd; 803 804 memset(&fwd, 0, sizeof(fwd)); 805 fwd.listen_path = packet_get_string(NULL); 806 debug("%s: cancel-streamlocal-forward path %s", __func__, 807 fwd.listen_path); 808 809 success = channel_cancel_rport_listener(ssh, &fwd); 810 free(fwd.listen_path); 811 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 812 no_more_sessions = 1; 813 success = 1; 814 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 815 success = server_input_hostkeys_prove(ssh, &resp); 816 } 817 if (want_reply) { 818 packet_start(success ? 819 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 820 if (success && resp != NULL) 821 ssh_packet_put_raw(ssh, sshbuf_ptr(resp), 822 sshbuf_len(resp)); 823 packet_send(); 824 packet_write_wait(); 825 } 826 free(rtype); 827 sshbuf_free(resp); 828 return 0; 829 } 830 831 static int 832 server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 833 { 834 Channel *c; 835 int id, reply, success = 0; 836 char *rtype; 837 838 id = packet_get_int(); 839 rtype = packet_get_string(NULL); 840 reply = packet_get_char(); 841 842 debug("server_input_channel_req: channel %d request %s reply %d", 843 id, rtype, reply); 844 845 if ((c = channel_lookup(ssh, id)) == NULL) 846 packet_disconnect("server_input_channel_req: " 847 "unknown channel %d", id); 848 if (!strcmp(rtype, "eow@openssh.com")) { 849 packet_check_eom(); 850 chan_rcvd_eow(ssh, c); 851 } else if ((c->type == SSH_CHANNEL_LARVAL || 852 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 853 success = session_input_channel_req(ssh, c, rtype); 854 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 855 if (!c->have_remote_id) 856 fatal("%s: channel %d: no remote_id", 857 __func__, c->self); 858 packet_start(success ? 859 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 860 packet_put_int(c->remote_id); 861 packet_send(); 862 } 863 free(rtype); 864 return 0; 865 } 866 867 static void 868 server_init_dispatch(void) 869 { 870 debug("server_init_dispatch"); 871 dispatch_init(&dispatch_protocol_error); 872 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 873 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 874 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 875 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 876 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 877 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 878 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 879 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 880 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 881 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 882 /* client_alive */ 883 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 884 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 885 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 886 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 887 /* rekeying */ 888 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 889 } 890