1/* $OpenBSD: serverloop.c,v 1.209 2018/07/27 05:13:02 dtucker 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 "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 "sshbuf.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 "sshkey.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 81extern ServerOptions options; 82 83/* XXX */ 84extern Authctxt *the_authctxt; 85extern struct sshauthopt *auth_opts; 86extern int use_privsep; 87 88static int no_more_sessions = 0; /* Disallow further sessions. */ 89 90/* 91 * This SIGCHLD kludge is used to detect when the child exits. The server 92 * will exit after that, as soon as forwarded connections have terminated. 93 */ 94 95static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 96 97/* Cleanup on signals (!use_privsep case only) */ 98static volatile sig_atomic_t received_sigterm = 0; 99 100/* prototypes */ 101static void server_init_dispatch(void); 102 103/* requested tunnel forwarding interface(s), shared with session.c */ 104char *tun_fwd_ifnames = NULL; 105 106/* returns 1 if bind to specified port by specified user is permitted */ 107static int 108bind_permitted(int port, uid_t uid) 109{ 110 if (use_privsep) 111 return 1; /* allow system to decide */ 112 if (port < IPPORT_RESERVED && uid != 0) 113 return 0; 114 return 1; 115} 116 117/* 118 * we write to this pipe if a SIGCHLD is caught in order to avoid 119 * the race between select() and child_terminated 120 */ 121static int notify_pipe[2]; 122static void 123notify_setup(void) 124{ 125 if (pipe(notify_pipe) < 0) { 126 error("pipe(notify_pipe) failed %s", strerror(errno)); 127 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 128 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 129 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 130 close(notify_pipe[0]); 131 close(notify_pipe[1]); 132 } else { 133 set_nonblock(notify_pipe[0]); 134 set_nonblock(notify_pipe[1]); 135 return; 136 } 137 notify_pipe[0] = -1; /* read end */ 138 notify_pipe[1] = -1; /* write end */ 139} 140static void 141notify_parent(void) 142{ 143 if (notify_pipe[1] != -1) 144 (void)write(notify_pipe[1], "", 1); 145} 146static void 147notify_prepare(fd_set *readset) 148{ 149 if (notify_pipe[0] != -1) 150 FD_SET(notify_pipe[0], readset); 151} 152static void 153notify_done(fd_set *readset) 154{ 155 char c; 156 157 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 158 while (read(notify_pipe[0], &c, 1) != -1) 159 debug2("%s: reading", __func__); 160} 161 162/*ARGSUSED*/ 163static void 164sigchld_handler(int sig) 165{ 166 int save_errno = errno; 167 child_terminated = 1; 168 notify_parent(); 169 errno = save_errno; 170} 171 172/*ARGSUSED*/ 173static void 174sigterm_handler(int sig) 175{ 176 received_sigterm = sig; 177} 178 179static void 180client_alive_check(struct ssh *ssh) 181{ 182 int channel_id; 183 char remote_id[512]; 184 185 /* timeout, check to see how many we have had */ 186 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 187 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 188 logit("Timeout, client not responding from %s", remote_id); 189 cleanup_exit(255); 190 } 191 192 /* 193 * send a bogus global/channel request with "wantreply", 194 * we should get back a failure 195 */ 196 if ((channel_id = channel_find_open(ssh)) == -1) { 197 packet_start(SSH2_MSG_GLOBAL_REQUEST); 198 packet_put_cstring("keepalive@openssh.com"); 199 packet_put_char(1); /* boolean: want reply */ 200 } else { 201 channel_request_start(ssh, channel_id, 202 "keepalive@openssh.com", 1); 203 } 204 packet_send(); 205} 206 207/* 208 * Sleep in select() until we can do something. This will initialize the 209 * select masks. Upon return, the masks will indicate which descriptors 210 * have data or can accept data. Optionally, a maximum time can be specified 211 * for the duration of the wait (0 = infinite). 212 */ 213static void 214wait_until_can_do_something(struct ssh *ssh, 215 int connection_in, int connection_out, 216 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 217 u_int *nallocp, u_int64_t max_time_ms) 218{ 219 struct timeval tv, *tvp; 220 int ret; 221 time_t minwait_secs = 0; 222 int client_alive_scheduled = 0; 223 static time_t last_client_time; 224 225 /* Allocate and update select() masks for channel descriptors. */ 226 channel_prepare_select(ssh, readsetp, writesetp, maxfdp, 227 nallocp, &minwait_secs); 228 229 /* XXX need proper deadline system for rekey/client alive */ 230 if (minwait_secs != 0) 231 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 232 233 /* 234 * if using client_alive, set the max timeout accordingly, 235 * and indicate that this particular timeout was for client 236 * alive by setting the client_alive_scheduled flag. 237 * 238 * this could be randomized somewhat to make traffic 239 * analysis more difficult, but we're not doing it yet. 240 */ 241 if (options.client_alive_interval) { 242 uint64_t keepalive_ms = 243 (uint64_t)options.client_alive_interval * 1000; 244 245 client_alive_scheduled = 1; 246 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 247 max_time_ms = keepalive_ms; 248 } 249 250#if 0 251 /* wrong: bad condition XXX */ 252 if (channel_not_very_much_buffered_data()) 253#endif 254 FD_SET(connection_in, *readsetp); 255 notify_prepare(*readsetp); 256 257 /* 258 * If we have buffered packet data going to the client, mark that 259 * descriptor. 260 */ 261 if (packet_have_data_to_write()) 262 FD_SET(connection_out, *writesetp); 263 264 /* 265 * If child has terminated and there is enough buffer space to read 266 * from it, then read as much as is available and exit. 267 */ 268 if (child_terminated && packet_not_very_much_data_to_write()) 269 if (max_time_ms == 0 || client_alive_scheduled) 270 max_time_ms = 100; 271 272 if (max_time_ms == 0) 273 tvp = NULL; 274 else { 275 tv.tv_sec = max_time_ms / 1000; 276 tv.tv_usec = 1000 * (max_time_ms % 1000); 277 tvp = &tv; 278 } 279 280 /* Wait for something to happen, or the timeout to expire. */ 281 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 282 283 if (ret == -1) { 284 memset(*readsetp, 0, *nallocp); 285 memset(*writesetp, 0, *nallocp); 286 if (errno != EINTR) 287 error("select: %.100s", strerror(errno)); 288 } else if (client_alive_scheduled) { 289 time_t now = monotime(); 290 291 if (ret == 0) { /* timeout */ 292 client_alive_check(ssh); 293 } else if (FD_ISSET(connection_in, *readsetp)) { 294 last_client_time = now; 295 } else if (last_client_time != 0 && last_client_time + 296 options.client_alive_interval <= now) { 297 client_alive_check(ssh); 298 last_client_time = now; 299 } 300 } 301 302 notify_done(*readsetp); 303} 304 305/* 306 * Processes input from the client and the program. Input data is stored 307 * in buffers and processed later. 308 */ 309static int 310process_input(struct ssh *ssh, fd_set *readset, int connection_in) 311{ 312 int len; 313 char buf[16384]; 314 315 /* Read and buffer any input data from the client. */ 316 if (FD_ISSET(connection_in, readset)) { 317 len = read(connection_in, buf, sizeof(buf)); 318 if (len == 0) { 319 verbose("Connection closed by %.100s port %d", 320 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 321 return -1; 322 } else if (len < 0) { 323 if (errno != EINTR && errno != EAGAIN && 324 errno != EWOULDBLOCK) { 325 verbose("Read error from remote host " 326 "%.100s port %d: %.100s", 327 ssh_remote_ipaddr(ssh), 328 ssh_remote_port(ssh), strerror(errno)); 329 cleanup_exit(255); 330 } 331 } else { 332 /* Buffer any received data. */ 333 packet_process_incoming(buf, len); 334 } 335 } 336 return 0; 337} 338 339/* 340 * Sends data from internal buffers to client program stdin. 341 */ 342static void 343process_output(fd_set *writeset, int connection_out) 344{ 345 /* Send any buffered packet data to the client. */ 346 if (FD_ISSET(connection_out, writeset)) 347 packet_write_poll(); 348} 349 350static void 351process_buffered_input_packets(struct ssh *ssh) 352{ 353 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); 354} 355 356static void 357collect_children(struct ssh *ssh) 358{ 359 pid_t pid; 360 sigset_t oset, nset; 361 int status; 362 363 /* block SIGCHLD while we check for dead children */ 364 sigemptyset(&nset); 365 sigaddset(&nset, SIGCHLD); 366 sigprocmask(SIG_BLOCK, &nset, &oset); 367 if (child_terminated) { 368 debug("Received SIGCHLD."); 369 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 370 (pid < 0 && errno == EINTR)) 371 if (pid > 0) 372 session_close_by_pid(ssh, pid, status); 373 child_terminated = 0; 374 } 375 sigprocmask(SIG_SETMASK, &oset, NULL); 376} 377 378void 379server_loop2(struct ssh *ssh, Authctxt *authctxt) 380{ 381 fd_set *readset = NULL, *writeset = NULL; 382 int max_fd; 383 u_int nalloc = 0, connection_in, connection_out; 384 u_int64_t rekey_timeout_ms = 0; 385 386 debug("Entering interactive session for SSH2."); 387 388 signal(SIGCHLD, sigchld_handler); 389 child_terminated = 0; 390 connection_in = packet_get_connection_in(); 391 connection_out = packet_get_connection_out(); 392 393 if (!use_privsep) { 394 signal(SIGTERM, sigterm_handler); 395 signal(SIGINT, sigterm_handler); 396 signal(SIGQUIT, sigterm_handler); 397 } 398 399 notify_setup(); 400 401 max_fd = MAXIMUM(connection_in, connection_out); 402 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 403 404 server_init_dispatch(); 405 406 for (;;) { 407 process_buffered_input_packets(ssh); 408 409 if (!ssh_packet_is_rekeying(ssh) && 410 packet_not_very_much_data_to_write()) 411 channel_output_poll(ssh); 412 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) 413 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 414 else 415 rekey_timeout_ms = 0; 416 417 wait_until_can_do_something(ssh, connection_in, connection_out, 418 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 419 420 if (received_sigterm) { 421 logit("Exiting on signal %d", (int)received_sigterm); 422 /* Clean up sessions, utmp, etc. */ 423 cleanup_exit(255); 424 } 425 426 collect_children(ssh); 427 if (!ssh_packet_is_rekeying(ssh)) 428 channel_after_select(ssh, readset, writeset); 429 if (process_input(ssh, readset, connection_in) < 0) 430 break; 431 process_output(writeset, connection_out); 432 } 433 collect_children(ssh); 434 435 free(readset); 436 free(writeset); 437 438 /* free all channels, no more reads and writes */ 439 channel_free_all(ssh); 440 441 /* free remaining sessions, e.g. remove wtmp entries */ 442 session_destroy_all(ssh, NULL); 443} 444 445static int 446server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) 447{ 448 debug("Got %d/%u for keepalive", type, seq); 449 /* 450 * reset timeout, since we got a sane answer from the client. 451 * even if this was generated by something other than 452 * the bogus CHANNEL_REQUEST we send for keepalives. 453 */ 454 packet_set_alive_timeouts(0); 455 return 0; 456} 457 458static Channel * 459server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) 460{ 461 Channel *c = NULL; 462 char *target, *originator; 463 u_short target_port, originator_port; 464 465 target = packet_get_string(NULL); 466 target_port = packet_get_int(); 467 originator = packet_get_string(NULL); 468 originator_port = packet_get_int(); 469 packet_check_eom(); 470 471 debug("%s: originator %s port %d, target %s port %d", __func__, 472 originator, originator_port, target, target_port); 473 474 /* XXX fine grained permissions */ 475 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 476 auth_opts->permit_port_forwarding_flag && 477 !options.disable_forwarding) { 478 c = channel_connect_to_port(ssh, target, target_port, 479 "direct-tcpip", "direct-tcpip", reason, errmsg); 480 } else { 481 logit("refused local port forward: " 482 "originator %s port %d, target %s port %d", 483 originator, originator_port, target, target_port); 484 if (reason != NULL) 485 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 486 } 487 488 free(originator); 489 free(target); 490 491 return c; 492} 493 494static Channel * 495server_request_direct_streamlocal(struct ssh *ssh) 496{ 497 Channel *c = NULL; 498 char *target, *originator; 499 u_short originator_port; 500 struct passwd *pw = the_authctxt->pw; 501 502 if (pw == NULL || !the_authctxt->valid) 503 fatal("%s: no/invalid user", __func__); 504 505 target = packet_get_string(NULL); 506 originator = packet_get_string(NULL); 507 originator_port = packet_get_int(); 508 packet_check_eom(); 509 510 debug("%s: originator %s port %d, target %s", __func__, 511 originator, originator_port, target); 512 513 /* XXX fine grained permissions */ 514 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 515 auth_opts->permit_port_forwarding_flag && 516 !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) { 517 c = channel_connect_to_path(ssh, target, 518 "direct-streamlocal@openssh.com", "direct-streamlocal"); 519 } else { 520 logit("refused streamlocal port forward: " 521 "originator %s port %d, target %s", 522 originator, originator_port, target); 523 } 524 525 free(originator); 526 free(target); 527 528 return c; 529} 530 531static Channel * 532server_request_tun(struct ssh *ssh) 533{ 534 Channel *c = NULL; 535 int mode, tun, sock; 536 char *tmp, *ifname = NULL; 537 538 mode = packet_get_int(); 539 switch (mode) { 540 case SSH_TUNMODE_POINTOPOINT: 541 case SSH_TUNMODE_ETHERNET: 542 break; 543 default: 544 packet_send_debug("Unsupported tunnel device mode."); 545 return NULL; 546 } 547 if ((options.permit_tun & mode) == 0) { 548 packet_send_debug("Server has rejected tunnel device " 549 "forwarding"); 550 return NULL; 551 } 552 553 tun = packet_get_int(); 554 if (auth_opts->force_tun_device != -1) { 555 if (tun != SSH_TUNID_ANY && auth_opts->force_tun_device != tun) 556 goto done; 557 tun = auth_opts->force_tun_device; 558 } 559 sock = tun_open(tun, mode, &ifname); 560 if (sock < 0) 561 goto done; 562 debug("Tunnel forwarding using interface %s", ifname); 563 564 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, 565 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 566 c->datagram = 1; 567#if defined(SSH_TUN_FILTER) 568 if (mode == SSH_TUNMODE_POINTOPOINT) 569 channel_register_filter(ssh, c->self, sys_tun_infilter, 570 sys_tun_outfilter, NULL, NULL); 571#endif 572 573 /* 574 * Update the list of names exposed to the session 575 * XXX remove these if the tunnels are closed (won't matter 576 * much if they are already in the environment though) 577 */ 578 tmp = tun_fwd_ifnames; 579 xasprintf(&tun_fwd_ifnames, "%s%s%s", 580 tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames, 581 tun_fwd_ifnames == NULL ? "" : ",", 582 ifname); 583 free(tmp); 584 free(ifname); 585 586 done: 587 if (c == NULL) 588 packet_send_debug("Failed to open the tunnel device."); 589 return c; 590} 591 592static Channel * 593server_request_session(struct ssh *ssh) 594{ 595 Channel *c; 596 597 debug("input_session_request"); 598 packet_check_eom(); 599 600 if (no_more_sessions) { 601 packet_disconnect("Possible attack: attempt to open a session " 602 "after additional sessions disabled"); 603 } 604 605 /* 606 * A server session has no fd to read or write until a 607 * CHANNEL_REQUEST for a shell is made, so we set the type to 608 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 609 * CHANNEL_REQUEST messages is registered. 610 */ 611 c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL, 612 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 613 0, "server-session", 1); 614 if (session_open(the_authctxt, c->self) != 1) { 615 debug("session open failed, free channel %d", c->self); 616 channel_free(ssh, c); 617 return NULL; 618 } 619 channel_register_cleanup(ssh, c->self, session_close_by_channel, 0); 620 return c; 621} 622 623static int 624server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 625{ 626 Channel *c = NULL; 627 char *ctype; 628 const char *errmsg = NULL; 629 int rchan, reason = SSH2_OPEN_CONNECT_FAILED; 630 u_int rmaxpack, rwindow, len; 631 632 ctype = packet_get_string(&len); 633 rchan = packet_get_int(); 634 rwindow = packet_get_int(); 635 rmaxpack = packet_get_int(); 636 637 debug("%s: ctype %s rchan %d win %d max %d", __func__, 638 ctype, rchan, rwindow, rmaxpack); 639 640 if (strcmp(ctype, "session") == 0) { 641 c = server_request_session(ssh); 642 } else if (strcmp(ctype, "direct-tcpip") == 0) { 643 c = server_request_direct_tcpip(ssh, &reason, &errmsg); 644 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 645 c = server_request_direct_streamlocal(ssh); 646 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 647 c = server_request_tun(ssh); 648 } 649 if (c != NULL) { 650 debug("%s: confirm %s", __func__, ctype); 651 c->remote_id = rchan; 652 c->have_remote_id = 1; 653 c->remote_window = rwindow; 654 c->remote_maxpacket = rmaxpack; 655 if (c->type != SSH_CHANNEL_CONNECTING) { 656 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 657 packet_put_int(c->remote_id); 658 packet_put_int(c->self); 659 packet_put_int(c->local_window); 660 packet_put_int(c->local_maxpacket); 661 packet_send(); 662 } 663 } else { 664 debug("%s: failure %s", __func__, ctype); 665 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 666 packet_put_int(rchan); 667 packet_put_int(reason); 668 packet_put_cstring(errmsg ? errmsg : "open failed"); 669 packet_put_cstring(""); 670 packet_send(); 671 } 672 free(ctype); 673 return 0; 674} 675 676static int 677server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) 678{ 679 struct sshbuf *resp = NULL; 680 struct sshbuf *sigbuf = NULL; 681 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 682 int r, ndx, kexsigtype, use_kexsigtype, success = 0; 683 const u_char *blob; 684 u_char *sig = 0; 685 size_t blen, slen; 686 687 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 688 fatal("%s: sshbuf_new", __func__); 689 690 kexsigtype = sshkey_type_plain( 691 sshkey_type_from_name(ssh->kex->hostkey_alg)); 692 while (ssh_packet_remaining(ssh) > 0) { 693 sshkey_free(key); 694 key = NULL; 695 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 696 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 697 error("%s: couldn't parse key: %s", 698 __func__, ssh_err(r)); 699 goto out; 700 } 701 /* 702 * Better check that this is actually one of our hostkeys 703 * before attempting to sign anything with it. 704 */ 705 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 706 error("%s: unknown host %s key", 707 __func__, sshkey_type(key)); 708 goto out; 709 } 710 /* 711 * XXX refactor: make kex->sign just use an index rather 712 * than passing in public and private keys 713 */ 714 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 715 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 716 error("%s: can't retrieve hostkey %d", __func__, ndx); 717 goto out; 718 } 719 sshbuf_reset(sigbuf); 720 free(sig); 721 sig = NULL; 722 /* 723 * For RSA keys, prefer to use the signature type negotiated 724 * during KEX to the default (SHA1). 725 */ 726 use_kexsigtype = kexsigtype == KEY_RSA && 727 sshkey_type_plain(key->type) == KEY_RSA; 728 if ((r = sshbuf_put_cstring(sigbuf, 729 "hostkeys-prove-00@openssh.com")) != 0 || 730 (r = sshbuf_put_string(sigbuf, 731 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 732 (r = sshkey_puts(key, sigbuf)) != 0 || 733 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 734 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), 735 use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 0 || 736 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 737 error("%s: couldn't prepare signature: %s", 738 __func__, ssh_err(r)); 739 goto out; 740 } 741 } 742 /* Success */ 743 *respp = resp; 744 resp = NULL; /* don't free it */ 745 success = 1; 746 out: 747 free(sig); 748 sshbuf_free(resp); 749 sshbuf_free(sigbuf); 750 sshkey_free(key); 751 return success; 752} 753 754static int 755server_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 756{ 757 char *rtype; 758 int want_reply; 759 int r, success = 0, allocated_listen_port = 0; 760 struct sshbuf *resp = NULL; 761 struct passwd *pw = the_authctxt->pw; 762 763 if (pw == NULL || !the_authctxt->valid) 764 fatal("%s: no/invalid user", __func__); 765 766 rtype = packet_get_string(NULL); 767 want_reply = packet_get_char(); 768 debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply); 769 770 /* -R style forwarding */ 771 if (strcmp(rtype, "tcpip-forward") == 0) { 772 struct Forward fwd; 773 774 memset(&fwd, 0, sizeof(fwd)); 775 fwd.listen_host = packet_get_string(NULL); 776 fwd.listen_port = (u_short)packet_get_int(); 777 debug("%s: tcpip-forward listen %s port %d", __func__, 778 fwd.listen_host, fwd.listen_port); 779 780 /* check permissions */ 781 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 782 !auth_opts->permit_port_forwarding_flag || 783 options.disable_forwarding || 784 (!want_reply && fwd.listen_port == 0) || 785 (fwd.listen_port != 0 && 786 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 787 success = 0; 788 packet_send_debug("Server has disabled port forwarding."); 789 } else { 790 /* Start listening on the port */ 791 success = channel_setup_remote_fwd_listener(ssh, &fwd, 792 &allocated_listen_port, &options.fwd_opts); 793 } 794 free(fwd.listen_host); 795 if ((resp = sshbuf_new()) == NULL) 796 fatal("%s: sshbuf_new", __func__); 797 if (allocated_listen_port != 0 && 798 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 799 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 800 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 801 struct Forward fwd; 802 803 memset(&fwd, 0, sizeof(fwd)); 804 fwd.listen_host = packet_get_string(NULL); 805 fwd.listen_port = (u_short)packet_get_int(); 806 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 807 fwd.listen_host, fwd.listen_port); 808 809 success = channel_cancel_rport_listener(ssh, &fwd); 810 free(fwd.listen_host); 811 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 812 struct Forward fwd; 813 814 memset(&fwd, 0, sizeof(fwd)); 815 fwd.listen_path = packet_get_string(NULL); 816 debug("%s: streamlocal-forward listen path %s", __func__, 817 fwd.listen_path); 818 819 /* check permissions */ 820 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 821 || !auth_opts->permit_port_forwarding_flag || 822 options.disable_forwarding || 823 (pw->pw_uid != 0 && !use_privsep)) { 824 success = 0; 825 packet_send_debug("Server has disabled " 826 "streamlocal forwarding."); 827 } else { 828 /* Start listening on the socket */ 829 success = channel_setup_remote_fwd_listener(ssh, 830 &fwd, NULL, &options.fwd_opts); 831 } 832 free(fwd.listen_path); 833 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 834 struct Forward fwd; 835 836 memset(&fwd, 0, sizeof(fwd)); 837 fwd.listen_path = packet_get_string(NULL); 838 debug("%s: cancel-streamlocal-forward path %s", __func__, 839 fwd.listen_path); 840 841 success = channel_cancel_rport_listener(ssh, &fwd); 842 free(fwd.listen_path); 843 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 844 no_more_sessions = 1; 845 success = 1; 846 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 847 success = server_input_hostkeys_prove(ssh, &resp); 848 } 849 if (want_reply) { 850 packet_start(success ? 851 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 852 if (success && resp != NULL) 853 ssh_packet_put_raw(ssh, sshbuf_ptr(resp), 854 sshbuf_len(resp)); 855 packet_send(); 856 packet_write_wait(); 857 } 858 free(rtype); 859 sshbuf_free(resp); 860 return 0; 861} 862 863static int 864server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 865{ 866 Channel *c; 867 int id, reply, success = 0; 868 char *rtype; 869 870 id = packet_get_int(); 871 rtype = packet_get_string(NULL); 872 reply = packet_get_char(); 873 874 debug("server_input_channel_req: channel %d request %s reply %d", 875 id, rtype, reply); 876 877 if ((c = channel_lookup(ssh, id)) == NULL) 878 packet_disconnect("server_input_channel_req: " 879 "unknown channel %d", id); 880 if (!strcmp(rtype, "eow@openssh.com")) { 881 packet_check_eom(); 882 chan_rcvd_eow(ssh, c); 883 } else if ((c->type == SSH_CHANNEL_LARVAL || 884 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 885 success = session_input_channel_req(ssh, c, rtype); 886 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 887 if (!c->have_remote_id) 888 fatal("%s: channel %d: no remote_id", 889 __func__, c->self); 890 packet_start(success ? 891 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 892 packet_put_int(c->remote_id); 893 packet_send(); 894 } 895 free(rtype); 896 return 0; 897} 898 899static void 900server_init_dispatch(void) 901{ 902 debug("server_init_dispatch"); 903 dispatch_init(&dispatch_protocol_error); 904 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 905 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 906 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 907 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 908 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 909 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 910 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 911 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 912 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 913 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 914 /* client_alive */ 915 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 916 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 917 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 918 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 919 /* rekeying */ 920 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 921} 922