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