1 /* $OpenBSD: serverloop.c,v 1.244 2025/09/25 06:23:19 jsg 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 #include <sys/time.h> 44 45 #include <netinet/in.h> 46 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <pwd.h> 50 #include <limits.h> 51 #include <poll.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 "ssh2.h" 69 #include "sshkey.h" 70 #include "cipher.h" 71 #include "kex.h" 72 #include "hostfile.h" 73 #include "auth.h" 74 #include "session.h" 75 #include "dispatch.h" 76 #include "auth-options.h" 77 #include "serverloop.h" 78 #include "ssherr.h" 79 80 extern ServerOptions options; 81 82 /* XXX */ 83 extern Authctxt *the_authctxt; 84 extern struct sshauthopt *auth_opts; 85 86 static int no_more_sessions = 0; /* Disallow further sessions. */ 87 88 static volatile sig_atomic_t child_terminated = 0; /* set on SIGCHLD */ 89 static volatile sig_atomic_t siginfo_received = 0; 90 91 /* prototypes */ 92 static void server_init_dispatch(struct ssh *); 93 94 /* requested tunnel forwarding interface(s), shared with session.c */ 95 char *tun_fwd_ifnames = NULL; 96 97 static void 98 sigchld_handler(int sig) 99 { 100 child_terminated = 1; 101 } 102 103 #ifdef SIGINFO 104 static void 105 siginfo_handler(int sig) 106 { 107 siginfo_received = 1; 108 } 109 #endif 110 111 static void 112 client_alive_check(struct ssh *ssh) 113 { 114 char remote_id[512]; 115 int r, channel_id; 116 117 /* timeout, check to see how many we have had */ 118 if (options.client_alive_count_max > 0 && 119 ssh_packet_inc_alive_timeouts(ssh) > 120 options.client_alive_count_max) { 121 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 122 logit("Timeout, client not responding from %s", remote_id); 123 cleanup_exit(255); 124 } 125 126 /* 127 * send a bogus global/channel request with "wantreply", 128 * we should get back a failure 129 */ 130 if ((channel_id = channel_find_open(ssh)) == -1) { 131 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 132 (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) 133 != 0 || 134 (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */ 135 fatal_fr(r, "compose"); 136 } else { 137 channel_request_start(ssh, channel_id, 138 "keepalive@openssh.com", 1); 139 } 140 if ((r = sshpkt_send(ssh)) != 0) 141 fatal_fr(r, "send"); 142 } 143 144 /* 145 * Sleep in ppoll() until we can do something. 146 * Optionally, a maximum time can be specified for the duration of 147 * the wait (0 = infinite). 148 */ 149 static void 150 wait_until_can_do_something(struct ssh *ssh, 151 int connection_in, int connection_out, struct pollfd **pfdp, 152 u_int *npfd_allocp, u_int *npfd_activep, sigset_t *sigsetp, 153 int *conn_in_readyp, int *conn_out_readyp) 154 { 155 struct timespec timeout; 156 char remote_id[512]; 157 int ret; 158 int client_alive_scheduled = 0; 159 u_int p; 160 time_t now; 161 static time_t last_client_time, unused_connection_expiry; 162 163 *conn_in_readyp = *conn_out_readyp = 0; 164 165 /* Prepare channel poll. First two pollfd entries are reserved */ 166 ptimeout_init(&timeout); 167 channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout); 168 now = monotime(); 169 if (*npfd_activep < 2) 170 fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */ 171 if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { 172 ptimeout_deadline_sec(&timeout, 173 ssh_packet_get_rekey_timeout(ssh)); 174 } 175 176 /* 177 * If no channels are open and UnusedConnectionTimeout is set, then 178 * start the clock to terminate the connection. 179 */ 180 if (options.unused_connection_timeout != 0) { 181 if (channel_still_open(ssh) || unused_connection_expiry == 0) { 182 unused_connection_expiry = now + 183 options.unused_connection_timeout; 184 } 185 ptimeout_deadline_monotime(&timeout, unused_connection_expiry); 186 } 187 188 /* 189 * if using client_alive, set the max timeout accordingly, 190 * and indicate that this particular timeout was for client 191 * alive by setting the client_alive_scheduled flag. 192 * 193 * this could be randomized somewhat to make traffic 194 * analysis more difficult, but we're not doing it yet. 195 */ 196 if (options.client_alive_interval) { 197 /* Time we last heard from the client OR sent a keepalive */ 198 if (last_client_time == 0) 199 last_client_time = now; 200 ptimeout_deadline_sec(&timeout, options.client_alive_interval); 201 /* XXX ? deadline_monotime(last_client_time + alive_interval) */ 202 client_alive_scheduled = 1; 203 } 204 205 #if 0 206 /* wrong: bad condition XXX */ 207 if (channel_not_very_much_buffered_data()) 208 #endif 209 /* Monitor client connection on reserved pollfd entries */ 210 (*pfdp)[0].fd = connection_in; 211 (*pfdp)[0].events = POLLIN; 212 (*pfdp)[1].fd = connection_out; 213 (*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0; 214 215 /* 216 * If child has terminated and there is enough buffer space to read 217 * from it, then read as much as is available and exit. 218 */ 219 if (child_terminated && ssh_packet_not_very_much_data_to_write(ssh)) 220 ptimeout_deadline_ms(&timeout, 100); 221 222 /* Wait for something to happen, or the timeout to expire. */ 223 ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp); 224 225 if (ret == -1) { 226 for (p = 0; p < *npfd_activep; p++) 227 (*pfdp)[p].revents = 0; 228 if (errno != EINTR) 229 fatal_f("ppoll: %.100s", strerror(errno)); 230 return; 231 } 232 233 *conn_in_readyp = (*pfdp)[0].revents != 0; 234 *conn_out_readyp = (*pfdp)[1].revents != 0; 235 236 now = monotime(); /* need to reset after ppoll() */ 237 /* ClientAliveInterval probing */ 238 if (client_alive_scheduled) { 239 if (ret == 0 && 240 now >= last_client_time + options.client_alive_interval) { 241 /* ppoll timed out and we're due to probe */ 242 client_alive_check(ssh); 243 last_client_time = now; 244 } else if (ret != 0 && *conn_in_readyp) { 245 /* Data from peer; reset probe timer. */ 246 last_client_time = now; 247 } 248 } 249 250 /* UnusedConnectionTimeout handling */ 251 if (unused_connection_expiry != 0 && 252 now > unused_connection_expiry && !channel_still_open(ssh)) { 253 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 254 logit("terminating inactive connection from %s", remote_id); 255 cleanup_exit(255); 256 } 257 } 258 259 /* 260 * Processes input from the client and the program. Input data is stored 261 * in buffers and processed later. 262 */ 263 static int 264 process_input(struct ssh *ssh, int connection_in) 265 { 266 int r; 267 268 if ((r = ssh_packet_process_read(ssh, connection_in)) == 0) 269 return 0; /* success */ 270 if (r == SSH_ERR_SYSTEM_ERROR) { 271 if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK) 272 return 0; 273 if (errno == EPIPE) { 274 logit("Connection closed by %.100s port %d", 275 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 276 return -1; 277 } 278 logit("Read error from remote host %s port %d: %s", 279 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 280 strerror(errno)); 281 cleanup_exit(255); 282 } 283 return -1; 284 } 285 286 /* 287 * Sends data from internal buffers to client program stdin. 288 */ 289 static void 290 process_output(struct ssh *ssh, int connection_out) 291 { 292 int r; 293 static int interactive = -1; 294 295 /* Send any buffered packet data to the client. */ 296 if (interactive != !channel_has_bulk(ssh)) { 297 interactive = !channel_has_bulk(ssh); 298 debug2_f("session QoS is now %s", interactive ? 299 "interactive" : "non-interactive"); 300 ssh_packet_set_interactive(ssh, interactive); 301 } 302 if ((r = ssh_packet_write_poll(ssh)) != 0) { 303 sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll", 304 __func__); 305 } 306 } 307 308 static void 309 process_buffered_input_packets(struct ssh *ssh) 310 { 311 ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); 312 } 313 314 static void 315 collect_children(struct ssh *ssh) 316 { 317 pid_t pid; 318 int status; 319 320 if (child_terminated) { 321 debug("Received SIGCHLD."); 322 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 323 (pid == -1 && errno == EINTR)) 324 if (pid > 0) 325 session_close_by_pid(ssh, pid, status); 326 child_terminated = 0; 327 } 328 } 329 330 void 331 server_loop2(struct ssh *ssh, Authctxt *authctxt) 332 { 333 struct pollfd *pfd = NULL; 334 u_int npfd_alloc = 0, npfd_active = 0; 335 int r, conn_in_ready, conn_out_ready; 336 u_int connection_in, connection_out; 337 sigset_t bsigset, osigset; 338 339 debug("Entering interactive session for SSH2."); 340 341 if (sigemptyset(&bsigset) == -1 || 342 sigaddset(&bsigset, SIGCHLD) == -1) 343 error_f("bsigset setup: %s", strerror(errno)); 344 ssh_signal(SIGCHLD, sigchld_handler); 345 #ifdef SIGINFO 346 if (sigaddset(&bsigset, SIGINFO) == -1) 347 error_f("bsigset setup: %s", strerror(errno)); 348 ssh_signal(SIGINFO, siginfo_handler); 349 #endif 350 child_terminated = 0; 351 connection_in = ssh_packet_get_connection_in(ssh); 352 connection_out = ssh_packet_get_connection_out(ssh); 353 354 server_init_dispatch(ssh); 355 356 for (;;) { 357 process_buffered_input_packets(ssh); 358 359 if (!ssh_packet_is_rekeying(ssh) && 360 ssh_packet_not_very_much_data_to_write(ssh)) 361 channel_output_poll(ssh); 362 363 /* 364 * Block SIGCHLD while we check for dead children, then pass 365 * the old signal mask through to ppoll() so that it'll wake 366 * up immediately if a child exits after we've called waitpid(). 367 */ 368 if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1) 369 error_f("bsigset sigprocmask: %s", strerror(errno)); 370 collect_children(ssh); 371 if (siginfo_received) { 372 siginfo_received = 0; 373 channel_report_open(ssh, SYSLOG_LEVEL_INFO); 374 } 375 wait_until_can_do_something(ssh, connection_in, connection_out, 376 &pfd, &npfd_alloc, &npfd_active, &osigset, 377 &conn_in_ready, &conn_out_ready); 378 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1) 379 error_f("osigset sigprocmask: %s", strerror(errno)); 380 381 channel_after_poll(ssh, pfd, npfd_active); 382 if (conn_in_ready && 383 process_input(ssh, connection_in) < 0) 384 break; 385 /* A timeout may have triggered rekeying */ 386 if ((r = ssh_packet_check_rekey(ssh)) != 0) 387 fatal_fr(r, "cannot start rekeying"); 388 if (conn_out_ready) 389 process_output(ssh, connection_out); 390 } 391 collect_children(ssh); 392 free(pfd); 393 394 /* free all channels, no more reads and writes */ 395 channel_free_all(ssh); 396 397 /* free remaining sessions, e.g. remove wtmp entries */ 398 session_destroy_all(ssh, NULL); 399 } 400 401 static int 402 server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) 403 { 404 debug("Got %d/%u for keepalive", type, seq); 405 /* 406 * reset timeout, since we got a sane answer from the client. 407 * even if this was generated by something other than 408 * the bogus CHANNEL_REQUEST we send for keepalives. 409 */ 410 ssh_packet_set_alive_timeouts(ssh, 0); 411 return 0; 412 } 413 414 static Channel * 415 server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) 416 { 417 Channel *c = NULL; 418 char *target = NULL, *originator = NULL; 419 u_int target_port = 0, originator_port = 0; 420 int r; 421 422 if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 || 423 (r = sshpkt_get_u32(ssh, &target_port)) != 0 || 424 (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 425 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 426 (r = sshpkt_get_end(ssh)) != 0) 427 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 428 if (target_port > 0xFFFF) { 429 error_f("invalid target port"); 430 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 431 goto out; 432 } 433 if (originator_port > 0xFFFF) { 434 error_f("invalid originator port"); 435 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 436 goto out; 437 } 438 439 debug_f("originator %s port %u, target %s port %u", 440 originator, originator_port, target, target_port); 441 442 /* XXX fine grained permissions */ 443 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 444 auth_opts->permit_port_forwarding_flag && 445 !options.disable_forwarding) { 446 c = channel_connect_to_port(ssh, target, target_port, 447 "direct-tcpip", "direct-tcpip", reason, errmsg); 448 } else { 449 logit("refused local port forward: " 450 "originator %s port %d, target %s port %d", 451 originator, originator_port, target, target_port); 452 if (reason != NULL) 453 *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; 454 } 455 456 out: 457 free(originator); 458 free(target); 459 return c; 460 } 461 462 static Channel * 463 server_request_direct_streamlocal(struct ssh *ssh) 464 { 465 Channel *c = NULL; 466 char *target = NULL, *originator = NULL; 467 u_int originator_port = 0; 468 struct passwd *pw = the_authctxt->pw; 469 int r; 470 471 if (pw == NULL || !the_authctxt->valid) 472 fatal_f("no/invalid user"); 473 474 if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 || 475 (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || 476 (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || 477 (r = sshpkt_get_end(ssh)) != 0) 478 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 479 if (originator_port > 0xFFFF) { 480 error_f("invalid originator port"); 481 goto out; 482 } 483 484 debug_f("originator %s port %d, target %s", 485 originator, originator_port, target); 486 487 /* XXX fine grained permissions */ 488 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 489 auth_opts->permit_port_forwarding_flag && 490 !options.disable_forwarding) { 491 c = channel_connect_to_path(ssh, target, 492 "direct-streamlocal@openssh.com", "direct-streamlocal"); 493 } else { 494 logit("refused streamlocal port forward: " 495 "originator %s port %d, target %s", 496 originator, originator_port, target); 497 } 498 499 out: 500 free(originator); 501 free(target); 502 return c; 503 } 504 505 static Channel * 506 server_request_tun(struct ssh *ssh) 507 { 508 Channel *c = NULL; 509 u_int mode, tun; 510 int r, sock; 511 char *tmp, *ifname = NULL; 512 513 if ((r = sshpkt_get_u32(ssh, &mode)) != 0) 514 sshpkt_fatal(ssh, r, "%s: parse mode", __func__); 515 switch (mode) { 516 case SSH_TUNMODE_POINTOPOINT: 517 case SSH_TUNMODE_ETHERNET: 518 break; 519 default: 520 ssh_packet_send_debug(ssh, "Unsupported tunnel device mode."); 521 return NULL; 522 } 523 if ((options.permit_tun & mode) == 0) { 524 ssh_packet_send_debug(ssh, "Server has rejected tunnel device " 525 "forwarding"); 526 return NULL; 527 } 528 529 if ((r = sshpkt_get_u32(ssh, &tun)) != 0) 530 sshpkt_fatal(ssh, r, "%s: parse device", __func__); 531 if (tun > INT_MAX) { 532 debug_f("invalid tun"); 533 goto done; 534 } 535 if (auth_opts->force_tun_device != -1) { 536 if (tun != SSH_TUNID_ANY && 537 auth_opts->force_tun_device != (int)tun) 538 goto done; 539 tun = auth_opts->force_tun_device; 540 } 541 sock = tun_open(tun, mode, &ifname); 542 if (sock < 0) 543 goto done; 544 debug("Tunnel forwarding using interface %s", ifname); 545 546 c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, 547 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 548 c->datagram = 1; 549 #if defined(SSH_TUN_FILTER) 550 if (mode == SSH_TUNMODE_POINTOPOINT) 551 channel_register_filter(ssh, c->self, sys_tun_infilter, 552 sys_tun_outfilter, NULL, NULL); 553 #endif 554 555 /* 556 * Update the list of names exposed to the session 557 * XXX remove these if the tunnels are closed (won't matter 558 * much if they are already in the environment though) 559 */ 560 tmp = tun_fwd_ifnames; 561 xasprintf(&tun_fwd_ifnames, "%s%s%s", 562 tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames, 563 tun_fwd_ifnames == NULL ? "" : ",", 564 ifname); 565 free(tmp); 566 free(ifname); 567 568 done: 569 if (c == NULL) 570 ssh_packet_send_debug(ssh, "Failed to open the tunnel device."); 571 return c; 572 } 573 574 static Channel * 575 server_request_session(struct ssh *ssh) 576 { 577 Channel *c; 578 int r; 579 580 debug("input_session_request"); 581 if ((r = sshpkt_get_end(ssh)) != 0) 582 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 583 584 if (no_more_sessions) { 585 ssh_packet_disconnect(ssh, "Possible attack: attempt to open a " 586 "session after additional sessions disabled"); 587 } 588 589 /* 590 * A server session has no fd to read or write until a 591 * CHANNEL_REQUEST for a shell is made, so we set the type to 592 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 593 * CHANNEL_REQUEST messages is registered. 594 */ 595 c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL, 596 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 597 0, "server-session", 1); 598 if (session_open(the_authctxt, c->self) != 1) { 599 debug("session open failed, free channel %d", c->self); 600 channel_free(ssh, c); 601 return NULL; 602 } 603 channel_register_cleanup(ssh, c->self, session_close_by_channel, 0); 604 return c; 605 } 606 607 static int 608 server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) 609 { 610 Channel *c = NULL; 611 char *ctype = NULL; 612 const char *errmsg = NULL; 613 int r, reason = SSH2_OPEN_CONNECT_FAILED; 614 u_int rchan = 0, rmaxpack = 0, rwindow = 0; 615 616 if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 || 617 (r = sshpkt_get_u32(ssh, &rchan)) != 0 || 618 (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || 619 (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) 620 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 621 debug_f("ctype %s rchan %u win %u max %u", 622 ctype, rchan, rwindow, rmaxpack); 623 624 if (strcmp(ctype, "session") == 0) { 625 c = server_request_session(ssh); 626 } else if (strcmp(ctype, "direct-tcpip") == 0) { 627 c = server_request_direct_tcpip(ssh, &reason, &errmsg); 628 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 629 c = server_request_direct_streamlocal(ssh); 630 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 631 c = server_request_tun(ssh); 632 } 633 if (c != NULL) { 634 debug_f("confirm %s", ctype); 635 c->remote_id = rchan; 636 c->have_remote_id = 1; 637 c->remote_window = rwindow; 638 c->remote_maxpacket = rmaxpack; 639 if (c->type != SSH_CHANNEL_CONNECTING) { 640 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || 641 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 642 (r = sshpkt_put_u32(ssh, c->self)) != 0 || 643 (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || 644 (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 || 645 (r = sshpkt_send(ssh)) != 0) { 646 sshpkt_fatal(ssh, r, 647 "%s: send open confirm", __func__); 648 } 649 } 650 } else { 651 debug_f("failure %s", ctype); 652 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || 653 (r = sshpkt_put_u32(ssh, rchan)) != 0 || 654 (r = sshpkt_put_u32(ssh, reason)) != 0 || 655 (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 || 656 (r = sshpkt_put_cstring(ssh, "")) != 0 || 657 (r = sshpkt_send(ssh)) != 0) { 658 sshpkt_fatal(ssh, r, 659 "%s: send open failure", __func__); 660 } 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, success = 0; 673 const u_char *blob; 674 const char *sigalg, *kex_rsa_sigalg = NULL; 675 u_char *sig = NULL; 676 size_t blen, slen; 677 678 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 679 fatal_f("sshbuf_new"); 680 if (sshkey_type_plain(sshkey_type_from_name( 681 ssh->kex->hostkey_alg)) == KEY_RSA) 682 kex_rsa_sigalg = ssh->kex->hostkey_alg; 683 while (ssh_packet_remaining(ssh) > 0) { 684 sshkey_free(key); 685 key = NULL; 686 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 687 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 688 error_fr(r, "parse key"); 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_f("unknown host %s key", sshkey_type(key)); 697 goto out; 698 } 699 /* 700 * XXX refactor: make kex->sign just use an index rather 701 * than passing in public and private keys 702 */ 703 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 704 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 705 error_f("can't retrieve hostkey %d", ndx); 706 goto out; 707 } 708 sshbuf_reset(sigbuf); 709 free(sig); 710 sig = NULL; 711 /* 712 * For RSA keys, prefer to use the signature type negotiated 713 * during KEX to the default (SHA1). 714 */ 715 sigalg = sshkey_ssh_name(key); 716 if (sshkey_type_plain(key->type) == KEY_RSA) { 717 if (kex_rsa_sigalg != NULL) 718 sigalg = kex_rsa_sigalg; 719 else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED) 720 sigalg = "rsa-sha2-512"; 721 else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED) 722 sigalg = "rsa-sha2-256"; 723 } 724 725 debug3_f("sign %s key (index %d) using sigalg %s", 726 sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg); 727 if ((r = sshbuf_put_cstring(sigbuf, 728 "hostkeys-prove-00@openssh.com")) != 0 || 729 (r = sshbuf_put_stringb(sigbuf, 730 ssh->kex->session_id)) != 0 || 731 (r = sshkey_puts(key, sigbuf)) != 0 || 732 (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen, 733 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 || 734 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 735 error_fr(r, "assemble signature"); 736 goto out; 737 } 738 } 739 /* Success */ 740 *respp = resp; 741 resp = NULL; /* don't free it */ 742 success = 1; 743 out: 744 free(sig); 745 sshbuf_free(resp); 746 sshbuf_free(sigbuf); 747 sshkey_free(key); 748 return success; 749 } 750 751 static int 752 server_input_global_request(int type, u_int32_t seq, struct ssh *ssh) 753 { 754 char *rtype = NULL; 755 u_char want_reply = 0; 756 int r, success = 0, allocated_listen_port = 0; 757 u_int port = 0; 758 struct sshbuf *resp = NULL; 759 struct passwd *pw = the_authctxt->pw; 760 struct Forward fwd; 761 762 memset(&fwd, 0, sizeof(fwd)); 763 if (pw == NULL || !the_authctxt->valid) 764 fatal_f("no/invalid user"); 765 766 if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 767 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 768 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 769 debug_f("rtype %s want_reply %d", rtype, want_reply); 770 771 /* -R style forwarding */ 772 if (strcmp(rtype, "tcpip-forward") == 0) { 773 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 || 774 (r = sshpkt_get_u32(ssh, &port)) != 0) 775 sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__); 776 debug_f("tcpip-forward listen %s port %u", 777 fwd.listen_host, port); 778 if (port <= INT_MAX) 779 fwd.listen_port = (int)port; 780 /* check permissions */ 781 if (port > INT_MAX || 782 (options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 783 !auth_opts->permit_port_forwarding_flag || 784 options.disable_forwarding || 785 (!want_reply && fwd.listen_port == 0)) { 786 success = 0; 787 ssh_packet_send_debug(ssh, "Server has disabled port forwarding."); 788 } else { 789 /* Start listening on the port */ 790 success = channel_setup_remote_fwd_listener(ssh, &fwd, 791 &allocated_listen_port, &options.fwd_opts); 792 } 793 if ((resp = sshbuf_new()) == NULL) 794 fatal_f("sshbuf_new"); 795 if (allocated_listen_port != 0 && 796 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 797 fatal_fr(r, "sshbuf_put_u32"); 798 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 799 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 || 800 (r = sshpkt_get_u32(ssh, &port)) != 0) 801 sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__); 802 803 debug_f("cancel-tcpip-forward addr %s port %d", 804 fwd.listen_host, port); 805 if (port <= INT_MAX) { 806 fwd.listen_port = (int)port; 807 success = channel_cancel_rport_listener(ssh, &fwd); 808 } 809 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 810 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0) 811 sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__); 812 debug_f("streamlocal-forward listen path %s", 813 fwd.listen_path); 814 815 /* check permissions */ 816 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 817 || !auth_opts->permit_port_forwarding_flag || 818 options.disable_forwarding) { 819 success = 0; 820 ssh_packet_send_debug(ssh, "Server has disabled " 821 "streamlocal forwarding."); 822 } else { 823 /* Start listening on the socket */ 824 success = channel_setup_remote_fwd_listener(ssh, 825 &fwd, NULL, &options.fwd_opts); 826 } 827 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 828 if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0) 829 sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__); 830 debug_f("cancel-streamlocal-forward path %s", 831 fwd.listen_path); 832 833 success = channel_cancel_rport_listener(ssh, &fwd); 834 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 835 no_more_sessions = 1; 836 success = 1; 837 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 838 success = server_input_hostkeys_prove(ssh, &resp); 839 } 840 /* XXX sshpkt_get_end() */ 841 if (want_reply) { 842 if ((r = sshpkt_start(ssh, success ? 843 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 || 844 (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) || 845 (r = sshpkt_send(ssh)) != 0 || 846 (r = ssh_packet_write_wait(ssh)) != 0) 847 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 848 } 849 free(fwd.listen_host); 850 free(fwd.listen_path); 851 free(rtype); 852 sshbuf_free(resp); 853 return 0; 854 } 855 856 static int 857 server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) 858 { 859 Channel *c; 860 int r, success = 0; 861 char *rtype = NULL; 862 u_char want_reply = 0; 863 u_int id = 0; 864 865 if ((r = sshpkt_get_u32(ssh, &id)) != 0 || 866 (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || 867 (r = sshpkt_get_u8(ssh, &want_reply)) != 0) 868 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 869 870 debug("server_input_channel_req: channel %u request %s reply %d", 871 id, rtype, want_reply); 872 873 if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) { 874 ssh_packet_disconnect(ssh, "%s: unknown channel %d", 875 __func__, id); 876 } 877 if (!strcmp(rtype, "eow@openssh.com")) { 878 if ((r = sshpkt_get_end(ssh)) != 0) 879 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 880 chan_rcvd_eow(ssh, c); 881 } else if ((c->type == SSH_CHANNEL_LARVAL || 882 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 883 success = session_input_channel_req(ssh, c, rtype); 884 if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) { 885 if (!c->have_remote_id) 886 fatal_f("channel %d: no remote_id", c->self); 887 if ((r = sshpkt_start(ssh, success ? 888 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || 889 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || 890 (r = sshpkt_send(ssh)) != 0) 891 sshpkt_fatal(ssh, r, "%s: send reply", __func__); 892 } 893 free(rtype); 894 return 0; 895 } 896 897 static void 898 server_init_dispatch(struct ssh *ssh) 899 { 900 debug("server_init_dispatch"); 901 ssh_dispatch_init(ssh, &dispatch_protocol_error); 902 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 903 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); 904 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 905 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 906 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 907 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 908 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 909 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 910 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 911 ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 912 /* client_alive */ 913 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 914 ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 915 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 916 ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 917 /* rekeying */ 918 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); 919 } 920