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 "includes.h" 39 40 #include <sys/types.h> 41 #include <sys/wait.h> 42 #include <sys/socket.h> 43 #ifdef HAVE_SYS_TIME_H 44 # include <sys/time.h> 45 #endif 46 47 #include <netinet/in.h> 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <pwd.h> 52 #include <signal.h> 53 #include <string.h> 54 #include <termios.h> 55 #include <unistd.h> 56 #include <stdarg.h> 57 58 #include "openbsd-compat/sys-queue.h" 59 #include "xmalloc.h" 60 #include "packet.h" 61 #include "buffer.h" 62 #include "log.h" 63 #include "misc.h" 64 #include "servconf.h" 65 #include "canohost.h" 66 #include "sshpty.h" 67 #include "channels.h" 68 #include "compat.h" 69 #include "ssh2.h" 70 #include "key.h" 71 #include "cipher.h" 72 #include "kex.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "session.h" 76 #include "dispatch.h" 77 #include "auth-options.h" 78 #include "serverloop.h" 79 #include "ssherr.h" 80 81 extern ServerOptions options; 82 83 /* XXX */ 84 extern Authctxt *the_authctxt; 85 extern int use_privsep; 86 87 static int no_more_sessions = 0; /* Disallow further sessions. */ 88 89 /* 90 * This SIGCHLD kludge is used to detect when the child exits. The server 91 * will exit after that, as soon as forwarded connections have terminated. 92 */ 93 94 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 95 96 /* Cleanup on signals (!use_privsep case only) */ 97 static volatile sig_atomic_t received_sigterm = 0; 98 99 /* prototypes */ 100 static void server_init_dispatch(void); 101 102 /* 103 * we write to this pipe if a SIGCHLD is caught in order to avoid 104 * the race between select() and child_terminated 105 */ 106 static int notify_pipe[2]; 107 static void 108 notify_setup(void) 109 { 110 if (pipe(notify_pipe) < 0) { 111 error("pipe(notify_pipe) failed %s", strerror(errno)); 112 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 113 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 114 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 115 close(notify_pipe[0]); 116 close(notify_pipe[1]); 117 } else { 118 set_nonblock(notify_pipe[0]); 119 set_nonblock(notify_pipe[1]); 120 return; 121 } 122 notify_pipe[0] = -1; /* read end */ 123 notify_pipe[1] = -1; /* write end */ 124 } 125 static void 126 notify_parent(void) 127 { 128 if (notify_pipe[1] != -1) 129 (void)write(notify_pipe[1], "", 1); 130 } 131 static void 132 notify_prepare(fd_set *readset) 133 { 134 if (notify_pipe[0] != -1) 135 FD_SET(notify_pipe[0], readset); 136 } 137 static void 138 notify_done(fd_set *readset) 139 { 140 char c; 141 142 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 143 while (read(notify_pipe[0], &c, 1) != -1) 144 debug2("notify_done: reading"); 145 } 146 147 /*ARGSUSED*/ 148 static void 149 sigchld_handler(int sig) 150 { 151 int save_errno = errno; 152 child_terminated = 1; 153 #ifndef _UNICOS 154 mysignal(SIGCHLD, sigchld_handler); 155 #endif 156 notify_parent(); 157 errno = save_errno; 158 } 159 160 /*ARGSUSED*/ 161 static void 162 sigterm_handler(int sig) 163 { 164 received_sigterm = sig; 165 } 166 167 static void 168 client_alive_check(struct ssh *ssh) 169 { 170 int channel_id; 171 172 /* timeout, check to see how many we have had */ 173 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 174 logit("Timeout, client not responding."); 175 cleanup_exit(255); 176 } 177 178 /* 179 * send a bogus global/channel request with "wantreply", 180 * we should get back a failure 181 */ 182 if ((channel_id = channel_find_open(ssh)) == -1) { 183 packet_start(SSH2_MSG_GLOBAL_REQUEST); 184 packet_put_cstring("keepalive@openssh.com"); 185 packet_put_char(1); /* boolean: want reply */ 186 } else { 187 channel_request_start(ssh, channel_id, 188 "keepalive@openssh.com", 1); 189 } 190 packet_send(); 191 } 192 193 /* 194 * Sleep in select() until we can do something. This will initialize the 195 * select masks. Upon return, the masks will indicate which descriptors 196 * have data or can accept data. Optionally, a maximum time can be specified 197 * for the duration of the wait (0 = infinite). 198 */ 199 static void 200 wait_until_can_do_something(struct ssh *ssh, 201 int connection_in, int connection_out, 202 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 203 u_int *nallocp, u_int64_t max_time_ms) 204 { 205 struct timeval tv, *tvp; 206 int ret; 207 time_t minwait_secs = 0; 208 int client_alive_scheduled = 0; 209 static time_t last_client_time; 210 211 /* Allocate and update select() masks for channel descriptors. */ 212 channel_prepare_select(ssh, readsetp, writesetp, maxfdp, 213 nallocp, &minwait_secs); 214 215 /* XXX need proper deadline system for rekey/client alive */ 216 if (minwait_secs != 0) 217 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 218 219 /* 220 * if using client_alive, set the max timeout accordingly, 221 * and indicate that this particular timeout was for client 222 * alive by setting the client_alive_scheduled flag. 223 * 224 * this could be randomized somewhat to make traffic 225 * analysis more difficult, but we're not doing it yet. 226 */ 227 if (options.client_alive_interval) { 228 uint64_t keepalive_ms = 229 (uint64_t)options.client_alive_interval * 1000; 230 231 client_alive_scheduled = 1; 232 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 233 max_time_ms = keepalive_ms; 234 } 235 236 #if 0 237 /* wrong: bad condition XXX */ 238 if (channel_not_very_much_buffered_data()) 239 #endif 240 FD_SET(connection_in, *readsetp); 241 notify_prepare(*readsetp); 242 243 /* 244 * If we have buffered packet data going to the client, mark that 245 * descriptor. 246 */ 247 if (packet_have_data_to_write()) 248 FD_SET(connection_out, *writesetp); 249 250 /* 251 * If child has terminated and there is enough buffer space to read 252 * from it, then read as much as is available and exit. 253 */ 254 if (child_terminated && packet_not_very_much_data_to_write()) 255 if (max_time_ms == 0 || client_alive_scheduled) 256 max_time_ms = 100; 257 258 if (max_time_ms == 0) 259 tvp = NULL; 260 else { 261 tv.tv_sec = max_time_ms / 1000; 262 tv.tv_usec = 1000 * (max_time_ms % 1000); 263 tvp = &tv; 264 } 265 266 /* Wait for something to happen, or the timeout to expire. */ 267 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 268 269 if (ret == -1) { 270 memset(*readsetp, 0, *nallocp); 271 memset(*writesetp, 0, *nallocp); 272 if (errno != EINTR) 273 error("select: %.100s", strerror(errno)); 274 } else if (client_alive_scheduled) { 275 time_t now = monotime(); 276 277 if (ret == 0) { /* timeout */ 278 client_alive_check(ssh); 279 } else if (FD_ISSET(connection_in, *readsetp)) { 280 last_client_time = now; 281 } else if (last_client_time != 0 && last_client_time + 282 options.client_alive_interval <= now) { 283 client_alive_check(ssh); 284 last_client_time = now; 285 } 286 } 287 288 notify_done(*readsetp); 289 } 290 291 /* 292 * Processes input from the client and the program. Input data is stored 293 * in buffers and processed later. 294 */ 295 static int 296 process_input(struct ssh *ssh, fd_set *readset, int connection_in) 297 { 298 int len; 299 char buf[16384]; 300 301 /* Read and buffer any input data from the client. */ 302 if (FD_ISSET(connection_in, readset)) { 303 len = read(connection_in, buf, sizeof(buf)); 304 if (len == 0) { 305 verbose("Connection closed by %.100s port %d", 306 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 307 return -1; 308 } else if (len < 0) { 309 if (errno != EINTR && errno != EAGAIN && 310 errno != EWOULDBLOCK) { 311 verbose("Read error from remote host " 312 "%.100s port %d: %.100s", 313 ssh_remote_ipaddr(ssh), 314 ssh_remote_port(ssh), strerror(errno)); 315 cleanup_exit(255); 316 } 317 } else { 318 /* Buffer any received data. */ 319 packet_process_incoming(buf, len); 320 } 321 } 322 return 0; 323 } 324 325 /* 326 * Sends data from internal buffers to client program stdin. 327 */ 328 static void 329 process_output(fd_set *writeset, int connection_out) 330 { 331 /* Send any buffered packet data to the client. */ 332 if (FD_ISSET(connection_out, writeset)) 333 packet_write_poll(); 334 } 335 336 static void 337 process_buffered_input_packets(struct ssh *ssh) 338 { 339 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); 340 } 341 342 static void 343 collect_children(struct ssh *ssh) 344 { 345 pid_t pid; 346 sigset_t oset, nset; 347 int status; 348 349 /* block SIGCHLD while we check for dead children */ 350 sigemptyset(&nset); 351 sigaddset(&nset, SIGCHLD); 352 sigprocmask(SIG_BLOCK, &nset, &oset); 353 if (child_terminated) { 354 debug("Received SIGCHLD."); 355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 356 (pid < 0 && errno == EINTR)) 357 if (pid > 0) 358 session_close_by_pid(ssh, pid, status); 359 child_terminated = 0; 360 } 361 sigprocmask(SIG_SETMASK, &oset, NULL); 362 } 363 364 void 365 server_loop2(struct ssh *ssh, Authctxt *authctxt) 366 { 367 fd_set *readset = NULL, *writeset = NULL; 368 int max_fd; 369 u_int nalloc = 0, connection_in, connection_out; 370 u_int64_t rekey_timeout_ms = 0; 371 372 debug("Entering interactive session for SSH2."); 373 374 mysignal(SIGCHLD, sigchld_handler); 375 child_terminated = 0; 376 connection_in = packet_get_connection_in(); 377 connection_out = packet_get_connection_out(); 378 379 if (!use_privsep) { 380 signal(SIGTERM, sigterm_handler); 381 signal(SIGINT, sigterm_handler); 382 signal(SIGQUIT, sigterm_handler); 383 } 384 385 notify_setup(); 386 387 max_fd = MAXIMUM(connection_in, connection_out); 388 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 389 390 server_init_dispatch(); 391 392 for (;;) { 393 process_buffered_input_packets(ssh); 394 395 if (!ssh_packet_is_rekeying(ssh) && 396 packet_not_very_much_data_to_write()) 397 channel_output_poll(ssh); 398 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) 399 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 400 else 401 rekey_timeout_ms = 0; 402 403 wait_until_can_do_something(ssh, connection_in, connection_out, 404 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 405 406 if (received_sigterm) { 407 logit("Exiting on signal %d", (int)received_sigterm); 408 /* Clean up sessions, utmp, etc. */ 409 cleanup_exit(255); 410 } 411 412 collect_children(ssh); 413 if (!ssh_packet_is_rekeying(ssh)) 414 channel_after_select(ssh, readset, writeset); 415 if (process_input(ssh, readset, connection_in) < 0) 416 break; 417 process_output(writeset, connection_out); 418 } 419 collect_children(ssh); 420 421 free(readset); 422 free(writeset); 423 424 /* free all channels, no more reads and writes */ 425 channel_free_all(ssh); 426 427 /* free remaining sessions, e.g. remove wtmp entries */ 428 session_destroy_all(ssh, NULL); 429 } 430 431 static int 432 server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) 433 { 434 debug("Got %d/%u for keepalive", type, seq); 435 /* 436 * reset timeout, since we got a sane answer from the client. 437 * even if this was generated by something other than 438 * the bogus CHANNEL_REQUEST we send for keepalives. 439 */ 440 packet_set_alive_timeouts(0); 441 return 0; 442 } 443 444 static Channel * 445 server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) 446 { 447 Channel *c = NULL; 448 char *target, *originator; 449 u_short target_port, originator_port; 450 451 target = packet_get_string(NULL); 452 target_port = packet_get_int(); 453 originator = packet_get_string(NULL); 454 originator_port = packet_get_int(); 455 packet_check_eom(); 456 457 debug("server_request_direct_tcpip: originator %s port %d, target %s " 458 "port %d", originator, originator_port, target, target_port); 459 460 /* XXX fine grained permissions */ 461 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 462 !no_port_forwarding_flag && !options.disable_forwarding) { 463 c = channel_connect_to_port(ssh, target, target_port, 464 "direct-tcpip", "direct-tcpip", reason, errmsg); 465 } else { 466 logit("refused local port forward: " 467 "originator %s port %d, target %s port %d", 468 originator, originator_port, target, target_port); 469 if (reason != NULL) 470 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 471 } 472 473 free(originator); 474 free(target); 475 476 return c; 477 } 478 479 static Channel * 480 server_request_direct_streamlocal(struct ssh *ssh) 481 { 482 Channel *c = NULL; 483 char *target, *originator; 484 u_short originator_port; 485 struct passwd *pw = the_authctxt->pw; 486 487 if (pw == NULL || !the_authctxt->valid) 488 fatal("server_input_global_request: no/invalid user"); 489 490 target = packet_get_string(NULL); 491 originator = packet_get_string(NULL); 492 originator_port = packet_get_int(); 493 packet_check_eom(); 494 495 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 496 originator, originator_port, target); 497 498 /* XXX fine grained permissions */ 499 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 500 !no_port_forwarding_flag && !options.disable_forwarding && 501 (pw->pw_uid == 0 || use_privsep)) { 502 c = channel_connect_to_path(ssh, target, 503 "direct-streamlocal@openssh.com", "direct-streamlocal"); 504 } else { 505 logit("refused streamlocal port forward: " 506 "originator %s port %d, target %s", 507 originator, originator_port, target); 508 } 509 510 free(originator); 511 free(target); 512 513 return c; 514 } 515 516 static Channel * 517 server_request_tun(struct ssh *ssh) 518 { 519 Channel *c = NULL; 520 int mode, tun; 521 int sock; 522 523 mode = packet_get_int(); 524 switch (mode) { 525 case SSH_TUNMODE_POINTOPOINT: 526 case SSH_TUNMODE_ETHERNET: 527 break; 528 default: 529 packet_send_debug("Unsupported tunnel device mode."); 530 return NULL; 531 } 532 if ((options.permit_tun & mode) == 0) { 533 packet_send_debug("Server has rejected tunnel device " 534 "forwarding"); 535 return NULL; 536 } 537 538 tun = packet_get_int(); 539 if (forced_tun_device != -1) { 540 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 541 goto done; 542 tun = forced_tun_device; 543 } 544 sock = tun_open(tun, mode); 545 if (sock < 0) 546 goto done; 547 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, 548 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 549 c->datagram = 1; 550 #if defined(SSH_TUN_FILTER) 551 if (mode == SSH_TUNMODE_POINTOPOINT) 552 channel_register_filter(ssh, c->self, sys_tun_infilter, 553 sys_tun_outfilter, NULL, NULL); 554 #endif 555 556 done: 557 if (c == NULL) 558 packet_send_debug("Failed to open the tunnel device."); 559 return c; 560 } 561 562 static Channel * 563 server_request_session(struct ssh *ssh) 564 { 565 Channel *c; 566 567 debug("input_session_request"); 568 packet_check_eom(); 569 570 if (no_more_sessions) { 571 packet_disconnect("Possible attack: attempt to open a session " 572 "after additional sessions disabled"); 573 } 574 575 /* 576 * A server session has no fd to read or write until a 577 * CHANNEL_REQUEST for a shell is made, so we set the type to 578 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 579 * CHANNEL_REQUEST messages is registered. 580 */ 581 c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL, 582 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 583 0, "server-session", 1); 584 if (session_open(the_authctxt, c->self) != 1) { 585 debug("session open failed, free channel %d", c->self); 586 channel_free(ssh, c); 587 return NULL; 588 } 589 channel_register_cleanup(ssh, c->self, session_close_by_channel, 0); 590 return c; 591 } 592 593 static int 594 server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 595 { 596 Channel *c = NULL; 597 char *ctype; 598 const char *errmsg = NULL; 599 int rchan, reason = SSH2_OPEN_CONNECT_FAILED; 600 u_int rmaxpack, rwindow, len; 601 602 ctype = packet_get_string(&len); 603 rchan = packet_get_int(); 604 rwindow = packet_get_int(); 605 rmaxpack = packet_get_int(); 606 607 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 608 ctype, rchan, rwindow, rmaxpack); 609 610 if (strcmp(ctype, "session") == 0) { 611 c = server_request_session(ssh); 612 } else if (strcmp(ctype, "direct-tcpip") == 0) { 613 c = server_request_direct_tcpip(ssh, &reason, &errmsg); 614 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 615 c = server_request_direct_streamlocal(ssh); 616 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 617 c = server_request_tun(ssh); 618 } 619 if (c != NULL) { 620 debug("server_input_channel_open: confirm %s", ctype); 621 c->remote_id = rchan; 622 c->have_remote_id = 1; 623 c->remote_window = rwindow; 624 c->remote_maxpacket = rmaxpack; 625 if (c->type != SSH_CHANNEL_CONNECTING) { 626 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 627 packet_put_int(c->remote_id); 628 packet_put_int(c->self); 629 packet_put_int(c->local_window); 630 packet_put_int(c->local_maxpacket); 631 packet_send(); 632 } 633 } else { 634 debug("server_input_channel_open: failure %s", ctype); 635 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 636 packet_put_int(rchan); 637 packet_put_int(reason); 638 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 639 packet_put_cstring(errmsg ? errmsg : "open failed"); 640 packet_put_cstring(""); 641 } 642 packet_send(); 643 } 644 free(ctype); 645 return 0; 646 } 647 648 static int 649 server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) 650 { 651 struct sshbuf *resp = NULL; 652 struct sshbuf *sigbuf = NULL; 653 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 654 int r, ndx, success = 0; 655 const u_char *blob; 656 u_char *sig = 0; 657 size_t blen, slen; 658 659 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 660 fatal("%s: sshbuf_new", __func__); 661 662 while (ssh_packet_remaining(ssh) > 0) { 663 sshkey_free(key); 664 key = NULL; 665 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 666 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 667 error("%s: couldn't parse key: %s", 668 __func__, ssh_err(r)); 669 goto out; 670 } 671 /* 672 * Better check that this is actually one of our hostkeys 673 * before attempting to sign anything with it. 674 */ 675 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 676 error("%s: unknown host %s key", 677 __func__, sshkey_type(key)); 678 goto out; 679 } 680 /* 681 * XXX refactor: make kex->sign just use an index rather 682 * than passing in public and private keys 683 */ 684 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 685 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 686 error("%s: can't retrieve hostkey %d", __func__, ndx); 687 goto out; 688 } 689 sshbuf_reset(sigbuf); 690 free(sig); 691 sig = NULL; 692 if ((r = sshbuf_put_cstring(sigbuf, 693 "hostkeys-prove-00@openssh.com")) != 0 || 694 (r = sshbuf_put_string(sigbuf, 695 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 696 (r = sshkey_puts(key, sigbuf)) != 0 || 697 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 698 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 || 699 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 700 error("%s: couldn't prepare signature: %s", 701 __func__, ssh_err(r)); 702 goto out; 703 } 704 } 705 /* Success */ 706 *respp = resp; 707 resp = NULL; /* don't free it */ 708 success = 1; 709 out: 710 free(sig); 711 sshbuf_free(resp); 712 sshbuf_free(sigbuf); 713 sshkey_free(key); 714 return success; 715 } 716 717 static int 718 server_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 719 { 720 char *rtype; 721 int want_reply; 722 int r, success = 0, allocated_listen_port = 0; 723 struct sshbuf *resp = NULL; 724 struct passwd *pw = the_authctxt->pw; 725 726 if (pw == NULL || !the_authctxt->valid) 727 fatal("server_input_global_request: no/invalid user"); 728 729 rtype = packet_get_string(NULL); 730 want_reply = packet_get_char(); 731 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 732 733 /* -R style forwarding */ 734 if (strcmp(rtype, "tcpip-forward") == 0) { 735 struct Forward fwd; 736 737 memset(&fwd, 0, sizeof(fwd)); 738 fwd.listen_host = packet_get_string(NULL); 739 fwd.listen_port = (u_short)packet_get_int(); 740 debug("server_input_global_request: tcpip-forward listen %s port %d", 741 fwd.listen_host, fwd.listen_port); 742 743 /* check permissions */ 744 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 745 no_port_forwarding_flag || options.disable_forwarding || 746 (!want_reply && fwd.listen_port == 0) || 747 (fwd.listen_port != 0 && 748 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 749 success = 0; 750 packet_send_debug("Server has disabled port forwarding."); 751 } else { 752 /* Start listening on the port */ 753 success = channel_setup_remote_fwd_listener(ssh, &fwd, 754 &allocated_listen_port, &options.fwd_opts); 755 } 756 free(fwd.listen_host); 757 if ((resp = sshbuf_new()) == NULL) 758 fatal("%s: sshbuf_new", __func__); 759 if (allocated_listen_port != 0 && 760 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 761 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 762 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 763 struct Forward fwd; 764 765 memset(&fwd, 0, sizeof(fwd)); 766 fwd.listen_host = packet_get_string(NULL); 767 fwd.listen_port = (u_short)packet_get_int(); 768 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 769 fwd.listen_host, fwd.listen_port); 770 771 success = channel_cancel_rport_listener(ssh, &fwd); 772 free(fwd.listen_host); 773 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 774 struct Forward fwd; 775 776 memset(&fwd, 0, sizeof(fwd)); 777 fwd.listen_path = packet_get_string(NULL); 778 debug("server_input_global_request: streamlocal-forward listen path %s", 779 fwd.listen_path); 780 781 /* check permissions */ 782 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 783 || no_port_forwarding_flag || options.disable_forwarding || 784 (pw->pw_uid != 0 && !use_privsep)) { 785 success = 0; 786 packet_send_debug("Server has disabled " 787 "streamlocal forwarding."); 788 } else { 789 /* Start listening on the socket */ 790 success = channel_setup_remote_fwd_listener(ssh, 791 &fwd, NULL, &options.fwd_opts); 792 } 793 free(fwd.listen_path); 794 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 795 struct Forward fwd; 796 797 memset(&fwd, 0, sizeof(fwd)); 798 fwd.listen_path = packet_get_string(NULL); 799 debug("%s: cancel-streamlocal-forward path %s", __func__, 800 fwd.listen_path); 801 802 success = channel_cancel_rport_listener(ssh, &fwd); 803 free(fwd.listen_path); 804 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 805 no_more_sessions = 1; 806 success = 1; 807 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 808 success = server_input_hostkeys_prove(ssh, &resp); 809 } 810 if (want_reply) { 811 packet_start(success ? 812 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 813 if (success && resp != NULL) 814 ssh_packet_put_raw(ssh, sshbuf_ptr(resp), 815 sshbuf_len(resp)); 816 packet_send(); 817 packet_write_wait(); 818 } 819 free(rtype); 820 sshbuf_free(resp); 821 return 0; 822 } 823 824 static int 825 server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 826 { 827 Channel *c; 828 int id, reply, success = 0; 829 char *rtype; 830 831 id = packet_get_int(); 832 rtype = packet_get_string(NULL); 833 reply = packet_get_char(); 834 835 debug("server_input_channel_req: channel %d request %s reply %d", 836 id, rtype, reply); 837 838 if ((c = channel_lookup(ssh, id)) == NULL) 839 packet_disconnect("server_input_channel_req: " 840 "unknown channel %d", id); 841 if (!strcmp(rtype, "eow@openssh.com")) { 842 packet_check_eom(); 843 chan_rcvd_eow(ssh, c); 844 } else if ((c->type == SSH_CHANNEL_LARVAL || 845 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 846 success = session_input_channel_req(ssh, c, rtype); 847 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 848 if (!c->have_remote_id) 849 fatal("%s: channel %d: no remote_id", 850 __func__, c->self); 851 packet_start(success ? 852 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 853 packet_put_int(c->remote_id); 854 packet_send(); 855 } 856 free(rtype); 857 return 0; 858 } 859 860 static void 861 server_init_dispatch(void) 862 { 863 debug("server_init_dispatch"); 864 dispatch_init(&dispatch_protocol_error); 865 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 866 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 867 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 868 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 869 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 870 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 871 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 872 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 873 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 874 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 875 /* client_alive */ 876 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 877 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 878 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 879 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 880 /* rekeying */ 881 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 882 } 883