1 /* $NetBSD: serverloop.c,v 1.16 2016/12/25 00:07:47 christos Exp $ */ 2 /* $OpenBSD: serverloop.c,v 1.189 2016/12/14 00:36:34 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * Server main loop for handling the interactive session. 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * SSH2 support by Markus Friedl. 17 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 2. Redistributions in binary form must reproduce the above copyright 25 * notice, this list of conditions and the following disclaimer in the 26 * documentation and/or other materials provided with the distribution. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #include "includes.h" 41 __RCSID("$NetBSD: serverloop.c,v 1.16 2016/12/25 00:07:47 christos Exp $"); 42 43 #include <sys/param.h> /* MIN MAX */ 44 #include <sys/types.h> 45 #include <sys/wait.h> 46 #include <sys/socket.h> 47 #include <sys/time.h> 48 #include <sys/queue.h> 49 50 #include <netinet/in.h> 51 52 #include <errno.h> 53 #include <fcntl.h> 54 #include <pwd.h> 55 #include <signal.h> 56 #include <string.h> 57 #include <termios.h> 58 #include <unistd.h> 59 #include <stdarg.h> 60 61 #include "xmalloc.h" 62 #include "packet.h" 63 #include "buffer.h" 64 #include "log.h" 65 #include "misc.h" 66 #include "servconf.h" 67 #include "canohost.h" 68 #include "sshpty.h" 69 #include "channels.h" 70 #include "compat.h" 71 #include "ssh2.h" 72 #include "key.h" 73 #include "cipher.h" 74 #include "kex.h" 75 #include "hostfile.h" 76 #include "auth.h" 77 #include "session.h" 78 #include "dispatch.h" 79 #include "auth-options.h" 80 #include "serverloop.h" 81 #include "ssherr.h" 82 83 static u_long stdin_bytes = 0; /* Number of bytes written to stdin. */ 84 static u_long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 85 86 extern ServerOptions options; 87 88 /* XXX */ 89 extern Authctxt *the_authctxt; 90 extern int use_privsep; 91 92 static int no_more_sessions = 0; /* Disallow further sessions. */ 93 94 /* 95 * This SIGCHLD kludge is used to detect when the child exits. The server 96 * will exit after that, as soon as forwarded connections have terminated. 97 */ 98 99 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 100 101 /* Cleanup on signals (!use_privsep case only) */ 102 static volatile sig_atomic_t received_sigterm = 0; 103 104 /* prototypes */ 105 static void server_init_dispatch(void); 106 107 /* 108 * Returns current time in seconds from Jan 1, 1970 with the maximum 109 * available resolution. 110 */ 111 112 static double 113 get_current_time(void) 114 { 115 struct timeval tv; 116 gettimeofday(&tv, NULL); 117 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; 118 } 119 120 /* 121 * we write to this pipe if a SIGCHLD is caught in order to avoid 122 * the race between select() and child_terminated 123 */ 124 static int notify_pipe[2]; 125 static void 126 notify_setup(void) 127 { 128 if (pipe(notify_pipe) < 0) { 129 error("pipe(notify_pipe) failed %s", strerror(errno)); 130 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 131 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 132 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 133 close(notify_pipe[0]); 134 close(notify_pipe[1]); 135 } else { 136 set_nonblock(notify_pipe[0]); 137 set_nonblock(notify_pipe[1]); 138 return; 139 } 140 notify_pipe[0] = -1; /* read end */ 141 notify_pipe[1] = -1; /* write end */ 142 } 143 static void 144 notify_parent(void) 145 { 146 if (notify_pipe[1] != -1) 147 (void)write(notify_pipe[1], "", 1); 148 } 149 static void 150 notify_prepare(fd_set *readset) 151 { 152 if (notify_pipe[0] != -1) 153 FD_SET(notify_pipe[0], readset); 154 } 155 static void 156 notify_done(fd_set *readset) 157 { 158 char c; 159 160 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 161 while (read(notify_pipe[0], &c, 1) != -1) 162 debug2("notify_done: reading"); 163 } 164 165 /*ARGSUSED*/ 166 static void 167 sigchld_handler(int sig) 168 { 169 int save_errno = errno; 170 child_terminated = 1; 171 signal(SIGCHLD, sigchld_handler); 172 notify_parent(); 173 errno = save_errno; 174 } 175 176 /*ARGSUSED*/ 177 static void 178 sigterm_handler(int sig) 179 { 180 received_sigterm = sig; 181 } 182 183 static void 184 client_alive_check(void) 185 { 186 int channel_id; 187 188 /* timeout, check to see how many we have had */ 189 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 190 logit("Timeout, client not responding."); 191 cleanup_exit(255); 192 } 193 194 /* 195 * send a bogus global/channel request with "wantreply", 196 * we should get back a failure 197 */ 198 if ((channel_id = channel_find_open()) == -1) { 199 packet_start(SSH2_MSG_GLOBAL_REQUEST); 200 packet_put_cstring("keepalive@openssh.com"); 201 packet_put_char(1); /* boolean: want reply */ 202 } else { 203 channel_request_start(channel_id, "keepalive@openssh.com", 1); 204 } 205 packet_send(); 206 } 207 208 /* 209 * Sleep in select() until we can do something. This will initialize the 210 * select masks. Upon return, the masks will indicate which descriptors 211 * have data or can accept data. Optionally, a maximum time can be specified 212 * for the duration of the wait (0 = infinite). 213 */ 214 static void 215 wait_until_can_do_something(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; 223 224 /* Allocate and update select() masks for channel descriptors. */ 225 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 226 &minwait_secs, 0); 227 228 /* XXX need proper deadline system for rekey/client alive */ 229 if (minwait_secs != 0) 230 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 231 232 /* 233 * if using client_alive, set the max timeout accordingly, 234 * and indicate that this particular timeout was for client 235 * alive by setting the client_alive_scheduled flag. 236 * 237 * this could be randomized somewhat to make traffic 238 * analysis more difficult, but we're not doing it yet. 239 */ 240 if (options.client_alive_interval) { 241 uint64_t keepalive_ms = 242 (uint64_t)options.client_alive_interval * 1000; 243 244 client_alive_scheduled = 1; 245 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 246 max_time_ms = keepalive_ms; 247 } 248 249 #if 0 250 /* wrong: bad condition XXX */ 251 if (channel_not_very_much_buffered_data()) 252 #endif 253 FD_SET(connection_in, *readsetp); 254 notify_prepare(*readsetp); 255 256 /* 257 * If we have buffered packet data going to the client, mark that 258 * descriptor. 259 */ 260 if (packet_have_data_to_write()) 261 FD_SET(connection_out, *writesetp); 262 263 /* 264 * If child has terminated and there is enough buffer space to read 265 * from it, then read as much as is available and exit. 266 */ 267 if (child_terminated && packet_not_very_much_data_to_write()) 268 if (max_time_ms == 0 || client_alive_scheduled) 269 max_time_ms = 100; 270 271 if (max_time_ms == 0) 272 tvp = NULL; 273 else { 274 tv.tv_sec = max_time_ms / 1000; 275 tv.tv_usec = 1000 * (max_time_ms % 1000); 276 tvp = &tv; 277 } 278 279 /* Wait for something to happen, or the timeout to expire. */ 280 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 281 282 if (ret == -1) { 283 memset(*readsetp, 0, *nallocp); 284 memset(*writesetp, 0, *nallocp); 285 if (errno != EINTR) 286 error("select: %.100s", strerror(errno)); 287 } else if (ret == 0 && client_alive_scheduled) 288 client_alive_check(); 289 290 notify_done(*readsetp); 291 } 292 293 /* 294 * Processes input from the client and the program. Input data is stored 295 * in buffers and processed later. 296 */ 297 static int 298 process_input(fd_set *readset, int connection_in) 299 { 300 struct ssh *ssh = active_state; /* XXX */ 301 int len; 302 char buf[16384]; 303 304 /* Read and buffer any input data from the client. */ 305 if (FD_ISSET(connection_in, readset)) { 306 len = read(connection_in, buf, sizeof(buf)); 307 if (len == 0) { 308 verbose("Connection closed by %.100s port %d", 309 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 310 return -1; 311 } else if (len < 0) { 312 if (errno != EINTR && errno != EAGAIN) { 313 verbose("Read error from remote host " 314 "%.100s port %d: %.100s", 315 ssh_remote_ipaddr(ssh), 316 ssh_remote_port(ssh), strerror(errno)); 317 cleanup_exit(255); 318 } 319 } else { 320 /* Buffer any received data. */ 321 packet_process_incoming(buf, len); 322 fdout_bytes += len; 323 } 324 } 325 return 0; 326 } 327 328 /* 329 * Sends data from internal buffers to client program stdin. 330 */ 331 static void 332 process_output(fd_set *writeset, int connection_out) 333 { 334 /* Send any buffered packet data to the client. */ 335 if (FD_ISSET(connection_out, writeset)) 336 stdin_bytes += packet_write_poll(); 337 } 338 339 static void 340 process_buffered_input_packets(void) 341 { 342 dispatch_run(DISPATCH_NONBLOCK, NULL, active_state); 343 } 344 345 static void 346 collect_children(void) 347 { 348 pid_t pid; 349 sigset_t oset, nset; 350 int status; 351 352 /* block SIGCHLD while we check for dead children */ 353 sigemptyset(&nset); 354 sigaddset(&nset, SIGCHLD); 355 sigprocmask(SIG_BLOCK, &nset, &oset); 356 if (child_terminated) { 357 debug("Received SIGCHLD."); 358 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 359 (pid < 0 && errno == EINTR)) 360 if (pid > 0) 361 session_close_by_pid(pid, status); 362 child_terminated = 0; 363 } 364 sigprocmask(SIG_SETMASK, &oset, NULL); 365 } 366 367 void 368 server_loop2(Authctxt *authctxt) 369 { 370 fd_set *readset = NULL, *writeset = NULL; 371 int max_fd; 372 u_int nalloc = 0, connection_in, connection_out; 373 u_int64_t rekey_timeout_ms = 0; 374 double start_time, total_time; 375 struct ssh *ssh = active_state; /* XXX */ 376 377 debug("Entering interactive session for SSH2."); 378 start_time = get_current_time(); 379 380 signal(SIGCHLD, sigchld_handler); 381 child_terminated = 0; 382 connection_in = packet_get_connection_in(); 383 connection_out = packet_get_connection_out(); 384 385 if (!use_privsep) { 386 signal(SIGTERM, sigterm_handler); 387 signal(SIGINT, sigterm_handler); 388 signal(SIGQUIT, sigterm_handler); 389 } 390 391 notify_setup(); 392 393 max_fd = MAXIMUM(connection_in, connection_out); 394 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 395 396 server_init_dispatch(); 397 398 for (;;) { 399 process_buffered_input_packets(); 400 401 if (!ssh_packet_is_rekeying(active_state) && 402 packet_not_very_much_data_to_write()) 403 channel_output_poll(); 404 if (options.rekey_interval > 0 && 405 !ssh_packet_is_rekeying(active_state)) 406 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 407 else 408 rekey_timeout_ms = 0; 409 410 wait_until_can_do_something(connection_in, connection_out, 411 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 412 413 if (received_sigterm) { 414 logit("Exiting on signal %d", (int)received_sigterm); 415 /* Clean up sessions, utmp, etc. */ 416 cleanup_exit(255); 417 } 418 419 collect_children(); 420 if (!ssh_packet_is_rekeying(active_state)) 421 channel_after_select(readset, writeset); 422 if (process_input(readset, connection_in) < 0) 423 break; 424 process_output(writeset, connection_out); 425 } 426 collect_children(); 427 428 free(readset); 429 free(writeset); 430 431 /* free all channels, no more reads and writes */ 432 channel_free_all(); 433 434 /* free remaining sessions, e.g. remove wtmp entries */ 435 session_destroy_all(NULL); 436 total_time = get_current_time() - start_time; 437 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 438 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 439 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 440 fdout_bytes / total_time); 441 } 442 443 static int 444 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 445 { 446 debug("Got %d/%u for keepalive", type, seq); 447 /* 448 * reset timeout, since we got a sane answer from the client. 449 * even if this was generated by something other than 450 * the bogus CHANNEL_REQUEST we send for keepalives. 451 */ 452 packet_set_alive_timeouts(0); 453 return 0; 454 } 455 456 static Channel * 457 server_request_direct_tcpip(void) 458 { 459 Channel *c = NULL; 460 char *target, *originator; 461 u_short target_port, originator_port; 462 463 target = packet_get_string(NULL); 464 target_port = packet_get_int(); 465 originator = packet_get_string(NULL); 466 originator_port = packet_get_int(); 467 packet_check_eom(); 468 469 debug("server_request_direct_tcpip: originator %s port %d, target %s " 470 "port %d", originator, originator_port, target, target_port); 471 472 /* XXX fine grained permissions */ 473 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 474 !no_port_forwarding_flag && !options.disable_forwarding) { 475 c = channel_connect_to_port(target, target_port, 476 "direct-tcpip", "direct-tcpip"); 477 } else { 478 logit("refused local port forward: " 479 "originator %s port %d, target %s port %d", 480 originator, originator_port, target, target_port); 481 } 482 483 free(originator); 484 free(target); 485 486 return c; 487 } 488 489 static Channel * 490 server_request_direct_streamlocal(void) 491 { 492 Channel *c = NULL; 493 char *target, *originator; 494 u_short originator_port; 495 496 target = packet_get_string(NULL); 497 originator = packet_get_string(NULL); 498 originator_port = packet_get_int(); 499 packet_check_eom(); 500 501 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 502 originator, originator_port, target); 503 504 /* XXX fine grained permissions */ 505 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 506 !no_port_forwarding_flag && !options.disable_forwarding && 507 use_privsep) { 508 c = channel_connect_to_path(target, 509 "direct-streamlocal@openssh.com", "direct-streamlocal"); 510 } else { 511 logit("refused streamlocal port forward: " 512 "originator %s port %d, target %s", 513 originator, originator_port, target); 514 } 515 516 free(originator); 517 free(target); 518 519 return c; 520 } 521 522 static Channel * 523 server_request_tun(void) 524 { 525 Channel *c = NULL; 526 int mode, tun; 527 int sock; 528 529 mode = packet_get_int(); 530 switch (mode) { 531 case SSH_TUNMODE_POINTOPOINT: 532 case SSH_TUNMODE_ETHERNET: 533 break; 534 default: 535 packet_send_debug("Unsupported tunnel device mode."); 536 return NULL; 537 } 538 if ((options.permit_tun & mode) == 0) { 539 packet_send_debug("Server has rejected tunnel device " 540 "forwarding"); 541 return NULL; 542 } 543 544 tun = packet_get_int(); 545 if (forced_tun_device != -1) { 546 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 547 goto done; 548 tun = forced_tun_device; 549 } 550 sock = tun_open(tun, mode); 551 if (sock < 0) 552 goto done; 553 if (options.hpn_disabled) 554 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 555 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 556 else 557 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 558 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 559 c->datagram = 1; 560 561 done: 562 if (c == NULL) 563 packet_send_debug("Failed to open the tunnel device."); 564 return c; 565 } 566 567 static Channel * 568 server_request_session(void) 569 { 570 Channel *c; 571 572 debug("input_session_request"); 573 packet_check_eom(); 574 575 if (no_more_sessions) { 576 packet_disconnect("Possible attack: attempt to open a session " 577 "after additional sessions disabled"); 578 } 579 580 /* 581 * A server session has no fd to read or write until a 582 * CHANNEL_REQUEST for a shell is made, so we set the type to 583 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 584 * CHANNEL_REQUEST messages is registered. 585 */ 586 c = channel_new("session", SSH_CHANNEL_LARVAL, 587 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 588 0, "server-session", 1); 589 if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) 590 c->dynamic_window = 1; 591 if (session_open(the_authctxt, c->self) != 1) { 592 debug("session open failed, free channel %d", c->self); 593 channel_free(c); 594 return NULL; 595 } 596 channel_register_cleanup(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, void *ctxt) 602 { 603 Channel *c = NULL; 604 char *ctype; 605 int rchan; 606 u_int rmaxpack, rwindow, len; 607 608 ctype = packet_get_string(&len); 609 rchan = packet_get_int(); 610 rwindow = packet_get_int(); 611 rmaxpack = packet_get_int(); 612 613 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 614 ctype, rchan, rwindow, rmaxpack); 615 616 if (strcmp(ctype, "session") == 0) { 617 c = server_request_session(); 618 } else if (strcmp(ctype, "direct-tcpip") == 0) { 619 c = server_request_direct_tcpip(); 620 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 621 c = server_request_direct_streamlocal(); 622 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 623 c = server_request_tun(); 624 } 625 if (c != NULL) { 626 debug("server_input_channel_open: confirm %s", ctype); 627 c->remote_id = rchan; 628 c->remote_window = rwindow; 629 c->remote_maxpacket = rmaxpack; 630 if (c->type != SSH_CHANNEL_CONNECTING) { 631 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 632 packet_put_int(c->remote_id); 633 packet_put_int(c->self); 634 packet_put_int(c->local_window); 635 packet_put_int(c->local_maxpacket); 636 packet_send(); 637 } 638 } else { 639 debug("server_input_channel_open: failure %s", ctype); 640 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 641 packet_put_int(rchan); 642 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 643 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 644 packet_put_cstring("open failed"); 645 packet_put_cstring(""); 646 } 647 packet_send(); 648 } 649 free(ctype); 650 return 0; 651 } 652 653 static int 654 server_input_hostkeys_prove(struct sshbuf **respp) 655 { 656 struct ssh *ssh = active_state; /* XXX */ 657 struct sshbuf *resp = NULL; 658 struct sshbuf *sigbuf = NULL; 659 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 660 int r, ndx, success = 0; 661 const u_char *blob; 662 u_char *sig = 0; 663 size_t blen, slen; 664 665 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 666 fatal("%s: sshbuf_new", __func__); 667 668 while (ssh_packet_remaining(ssh) > 0) { 669 sshkey_free(key); 670 key = NULL; 671 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 672 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 673 error("%s: couldn't parse key: %s", 674 __func__, ssh_err(r)); 675 goto out; 676 } 677 /* 678 * Better check that this is actually one of our hostkeys 679 * before attempting to sign anything with it. 680 */ 681 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 682 error("%s: unknown host %s key", 683 __func__, sshkey_type(key)); 684 goto out; 685 } 686 /* 687 * XXX refactor: make kex->sign just use an index rather 688 * than passing in public and private keys 689 */ 690 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 691 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 692 error("%s: can't retrieve hostkey %d", __func__, ndx); 693 goto out; 694 } 695 sshbuf_reset(sigbuf); 696 free(sig); 697 sig = NULL; 698 if ((r = sshbuf_put_cstring(sigbuf, 699 "hostkeys-prove-00@openssh.com")) != 0 || 700 (r = sshbuf_put_string(sigbuf, 701 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 702 (r = sshkey_puts(key, sigbuf)) != 0 || 703 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 704 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 || 705 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 706 error("%s: couldn't prepare signature: %s", 707 __func__, ssh_err(r)); 708 goto out; 709 } 710 } 711 /* Success */ 712 *respp = resp; 713 resp = NULL; /* don't free it */ 714 success = 1; 715 out: 716 free(sig); 717 sshbuf_free(resp); 718 sshbuf_free(sigbuf); 719 sshkey_free(key); 720 return success; 721 } 722 723 static int 724 server_input_global_request(int type, u_int32_t seq, void *ctxt) 725 { 726 char *rtype; 727 int want_reply; 728 int r, success = 0, allocated_listen_port = 0; 729 struct sshbuf *resp = NULL; 730 731 rtype = packet_get_string(NULL); 732 want_reply = packet_get_char(); 733 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 734 735 /* -R style forwarding */ 736 if (strcmp(rtype, "tcpip-forward") == 0) { 737 struct passwd *pw; 738 struct Forward fwd; 739 740 pw = the_authctxt->pw; 741 if (pw == NULL || !the_authctxt->valid) 742 fatal("server_input_global_request: no/invalid user"); 743 memset(&fwd, 0, sizeof(fwd)); 744 fwd.listen_host = packet_get_string(NULL); 745 fwd.listen_port = (u_short)packet_get_int(); 746 debug("server_input_global_request: tcpip-forward listen %s port %d", 747 fwd.listen_host, fwd.listen_port); 748 749 /* check permissions */ 750 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 751 no_port_forwarding_flag || options.disable_forwarding || 752 (!want_reply && fwd.listen_port == 0) || 753 (fwd.listen_port != 0 && 754 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 755 success = 0; 756 packet_send_debug("Server has disabled port forwarding."); 757 } else { 758 /* Start listening on the port */ 759 success = channel_setup_remote_fwd_listener(&fwd, 760 &allocated_listen_port, &options.fwd_opts); 761 } 762 free(fwd.listen_host); 763 if ((resp = sshbuf_new()) == NULL) 764 fatal("%s: sshbuf_new", __func__); 765 if (allocated_listen_port != 0 && 766 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 767 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 768 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 769 struct Forward fwd; 770 771 memset(&fwd, 0, sizeof(fwd)); 772 fwd.listen_host = packet_get_string(NULL); 773 fwd.listen_port = (u_short)packet_get_int(); 774 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 775 fwd.listen_host, fwd.listen_port); 776 777 success = channel_cancel_rport_listener(&fwd); 778 free(fwd.listen_host); 779 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 780 struct Forward fwd; 781 782 memset(&fwd, 0, sizeof(fwd)); 783 fwd.listen_path = packet_get_string(NULL); 784 debug("server_input_global_request: streamlocal-forward listen path %s", 785 fwd.listen_path); 786 787 /* check permissions */ 788 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 789 || no_port_forwarding_flag || options.disable_forwarding || 790 !use_privsep) { 791 success = 0; 792 packet_send_debug("Server has disabled port forwarding."); 793 } else { 794 /* Start listening on the socket */ 795 success = channel_setup_remote_fwd_listener( 796 &fwd, NULL, &options.fwd_opts); 797 } 798 free(fwd.listen_path); 799 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 800 struct Forward fwd; 801 802 memset(&fwd, 0, sizeof(fwd)); 803 fwd.listen_path = packet_get_string(NULL); 804 debug("%s: cancel-streamlocal-forward path %s", __func__, 805 fwd.listen_path); 806 807 success = channel_cancel_rport_listener(&fwd); 808 free(fwd.listen_path); 809 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 810 no_more_sessions = 1; 811 success = 1; 812 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 813 success = server_input_hostkeys_prove(&resp); 814 } 815 if (want_reply) { 816 packet_start(success ? 817 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 818 if (success && resp != NULL) 819 ssh_packet_put_raw(active_state, sshbuf_ptr(resp), 820 sshbuf_len(resp)); 821 packet_send(); 822 packet_write_wait(); 823 } 824 free(rtype); 825 sshbuf_free(resp); 826 return 0; 827 } 828 829 static int 830 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 831 { 832 Channel *c; 833 int id, reply, success = 0; 834 char *rtype; 835 836 id = packet_get_int(); 837 rtype = packet_get_string(NULL); 838 reply = packet_get_char(); 839 840 debug("server_input_channel_req: channel %d request %s reply %d", 841 id, rtype, reply); 842 843 if ((c = channel_lookup(id)) == NULL) 844 packet_disconnect("server_input_channel_req: " 845 "unknown channel %d", id); 846 if (!strcmp(rtype, "eow@openssh.com")) { 847 packet_check_eom(); 848 chan_rcvd_eow(c); 849 } else if ((c->type == SSH_CHANNEL_LARVAL || 850 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 851 success = session_input_channel_req(c, rtype); 852 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 853 packet_start(success ? 854 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 855 packet_put_int(c->remote_id); 856 packet_send(); 857 } 858 free(rtype); 859 return 0; 860 } 861 862 static void 863 server_init_dispatch(void) 864 { 865 debug("server_init_dispatch"); 866 dispatch_init(&dispatch_protocol_error); 867 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 868 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 869 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 870 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 871 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 872 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 873 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 874 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 875 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 876 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 877 /* client_alive */ 878 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 879 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 880 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 881 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 882 /* rekeying */ 883 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 884 } 885