1 /* $OpenBSD: sshd-session.c,v 1.9 2024/09/09 02:39:57 djm Exp $ */ 2 /* 3 * SSH2 implementation: 4 * Privilege Separation: 5 * 6 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 7 * Copyright (c) 2002 Niels Provos. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include "includes.h" 31 32 #include <sys/types.h> 33 #include <sys/ioctl.h> 34 #include <sys/socket.h> 35 #ifdef HAVE_SYS_STAT_H 36 # include <sys/stat.h> 37 #endif 38 #ifdef HAVE_SYS_TIME_H 39 # include <sys/time.h> 40 #endif 41 #include "openbsd-compat/sys-tree.h" 42 #include "openbsd-compat/sys-queue.h" 43 #include <sys/wait.h> 44 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <netdb.h> 48 #ifdef HAVE_PATHS_H 49 # include <paths.h> 50 #endif 51 #include <pwd.h> 52 #include <grp.h> 53 #include <signal.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <stdarg.h> 58 #include <unistd.h> 59 #include <limits.h> 60 61 #ifdef WITH_OPENSSL 62 #include <openssl/bn.h> 63 #include <openssl/evp.h> 64 #include <openssl/rand.h> 65 #include "openbsd-compat/openssl-compat.h" 66 #endif 67 68 #ifdef HAVE_SECUREWARE 69 #include <sys/security.h> 70 #include <prot.h> 71 #endif 72 73 #include "xmalloc.h" 74 #include "ssh.h" 75 #include "ssh2.h" 76 #include "sshpty.h" 77 #include "packet.h" 78 #include "log.h" 79 #include "sshbuf.h" 80 #include "misc.h" 81 #include "match.h" 82 #include "servconf.h" 83 #include "uidswap.h" 84 #include "compat.h" 85 #include "cipher.h" 86 #include "digest.h" 87 #include "sshkey.h" 88 #include "kex.h" 89 #include "authfile.h" 90 #include "pathnames.h" 91 #include "atomicio.h" 92 #include "canohost.h" 93 #include "hostfile.h" 94 #include "auth.h" 95 #include "authfd.h" 96 #include "msg.h" 97 #include "dispatch.h" 98 #include "channels.h" 99 #include "session.h" 100 #include "monitor.h" 101 #ifdef GSSAPI 102 #include "ssh-gss.h" 103 #endif 104 #include "monitor_wrap.h" 105 #include "ssh-sandbox.h" 106 #include "auth-options.h" 107 #include "version.h" 108 #include "ssherr.h" 109 #include "sk-api.h" 110 #include "srclimit.h" 111 #include "dh.h" 112 113 /* Re-exec fds */ 114 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 115 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 116 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 117 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 118 119 extern char *__progname; 120 121 /* Server configuration options. */ 122 ServerOptions options; 123 124 /* Name of the server configuration file. */ 125 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 126 127 /* 128 * Debug mode flag. This can be set on the command line. If debug 129 * mode is enabled, extra debugging output will be sent to the system 130 * log, the daemon will not go to background, and will exit after processing 131 * the first connection. 132 */ 133 int debug_flag = 0; 134 135 /* Flag indicating that the daemon is being started from inetd. */ 136 static int inetd_flag = 0; 137 138 /* debug goes to stderr unless inetd_flag is set */ 139 static int log_stderr = 0; 140 141 /* Saved arguments to main(). */ 142 static char **saved_argv; 143 static int saved_argc; 144 145 /* Daemon's agent connection */ 146 int auth_sock = -1; 147 static int have_agent = 0; 148 149 /* 150 * Any really sensitive data in the application is contained in this 151 * structure. The idea is that this structure could be locked into memory so 152 * that the pages do not get written into swap. However, there are some 153 * problems. The private key contains BIGNUMs, and we do not (in principle) 154 * have access to the internals of them, and locking just the structure is 155 * not very useful. Currently, memory locking is not implemented. 156 */ 157 struct { 158 u_int num_hostkeys; 159 struct sshkey **host_keys; /* all private host keys */ 160 struct sshkey **host_pubkeys; /* all public host keys */ 161 struct sshkey **host_certificates; /* all public host certificates */ 162 } sensitive_data; 163 164 /* record remote hostname or ip */ 165 u_int utmp_len = HOST_NAME_MAX+1; 166 167 static int startup_pipe = -1; /* in child */ 168 169 /* variables used for privilege separation */ 170 struct monitor *pmonitor = NULL; 171 int privsep_is_preauth = 1; 172 static int privsep_chroot = 1; 173 174 /* Unprivileged user */ 175 struct passwd *privsep_pw = NULL; 176 177 /* global connection state and authentication contexts */ 178 Authctxt *the_authctxt = NULL; 179 struct ssh *the_active_state; 180 181 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 182 struct sshauthopt *auth_opts = NULL; 183 184 /* sshd_config buffer */ 185 struct sshbuf *cfg; 186 187 /* Included files from the configuration file */ 188 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 189 190 /* message to be displayed after login */ 191 struct sshbuf *loginmsg; 192 193 /* Prototypes for various functions defined later in this file. */ 194 void destroy_sensitive_data(void); 195 void demote_sensitive_data(void); 196 static void do_ssh2_kex(struct ssh *); 197 198 /* 199 * Signal handler for the alarm after the login grace period has expired. 200 * As usual, this may only take signal-safe actions, even though it is 201 * terminal. 202 */ 203 static void 204 grace_alarm_handler(int sig) 205 { 206 /* 207 * Try to kill any processes that we have spawned, E.g. authorized 208 * keys command helpers or privsep children. 209 */ 210 if (getpgid(0) == getpid()) { 211 struct sigaction sa; 212 213 /* mask all other signals while in handler */ 214 memset(&sa, 0, sizeof(sa)); 215 sa.sa_handler = SIG_IGN; 216 sigfillset(&sa.sa_mask); 217 #if defined(SA_RESTART) 218 sa.sa_flags = SA_RESTART; 219 #endif 220 (void)sigaction(SIGTERM, &sa, NULL); 221 kill(0, SIGTERM); 222 } 223 _exit(EXIT_LOGIN_GRACE); 224 } 225 226 /* Destroy the host and server keys. They will no longer be needed. */ 227 void 228 destroy_sensitive_data(void) 229 { 230 u_int i; 231 232 for (i = 0; i < options.num_host_key_files; i++) { 233 if (sensitive_data.host_keys[i]) { 234 sshkey_free(sensitive_data.host_keys[i]); 235 sensitive_data.host_keys[i] = NULL; 236 } 237 if (sensitive_data.host_certificates[i]) { 238 sshkey_free(sensitive_data.host_certificates[i]); 239 sensitive_data.host_certificates[i] = NULL; 240 } 241 } 242 } 243 244 /* Demote private to public keys for network child */ 245 void 246 demote_sensitive_data(void) 247 { 248 struct sshkey *tmp; 249 u_int i; 250 int r; 251 252 for (i = 0; i < options.num_host_key_files; i++) { 253 if (sensitive_data.host_keys[i]) { 254 if ((r = sshkey_from_private( 255 sensitive_data.host_keys[i], &tmp)) != 0) 256 fatal_r(r, "could not demote host %s key", 257 sshkey_type(sensitive_data.host_keys[i])); 258 sshkey_free(sensitive_data.host_keys[i]); 259 sensitive_data.host_keys[i] = tmp; 260 } 261 /* Certs do not need demotion */ 262 } 263 } 264 265 static void 266 reseed_prngs(void) 267 { 268 u_int32_t rnd[256]; 269 270 #ifdef WITH_OPENSSL 271 RAND_poll(); 272 #endif 273 arc4random_stir(); /* noop on recent arc4random() implementations */ 274 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 275 276 #ifdef WITH_OPENSSL 277 RAND_seed(rnd, sizeof(rnd)); 278 /* give libcrypto a chance to notice the PID change */ 279 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 280 fatal("%s: RAND_bytes failed", __func__); 281 #endif 282 283 explicit_bzero(rnd, sizeof(rnd)); 284 } 285 286 static void 287 privsep_preauth_child(void) 288 { 289 gid_t gidset[1]; 290 291 /* Enable challenge-response authentication for privilege separation */ 292 privsep_challenge_enable(); 293 294 #ifdef GSSAPI 295 /* Cache supported mechanism OIDs for later use */ 296 ssh_gssapi_prepare_supported_oids(); 297 #endif 298 299 reseed_prngs(); 300 301 /* Demote the private keys to public keys. */ 302 demote_sensitive_data(); 303 304 /* Demote the child */ 305 if (privsep_chroot) { 306 /* Change our root directory */ 307 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 308 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 309 strerror(errno)); 310 if (chdir("/") == -1) 311 fatal("chdir(\"/\"): %s", strerror(errno)); 312 313 /* Drop our privileges */ 314 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 315 (u_int)privsep_pw->pw_gid); 316 gidset[0] = privsep_pw->pw_gid; 317 if (setgroups(1, gidset) == -1) 318 fatal("setgroups: %.100s", strerror(errno)); 319 permanently_set_uid(privsep_pw); 320 } 321 } 322 323 static int 324 privsep_preauth(struct ssh *ssh) 325 { 326 int status, r; 327 pid_t pid; 328 struct ssh_sandbox *box = NULL; 329 330 /* Set up unprivileged child process to deal with network data */ 331 pmonitor = monitor_init(); 332 /* Store a pointer to the kex for later rekeying */ 333 pmonitor->m_pkex = &ssh->kex; 334 335 box = ssh_sandbox_init(pmonitor); 336 pid = fork(); 337 if (pid == -1) { 338 fatal("fork of unprivileged child failed"); 339 } else if (pid != 0) { 340 debug2("Network child is on pid %ld", (long)pid); 341 342 pmonitor->m_pid = pid; 343 if (have_agent) { 344 r = ssh_get_authentication_socket(&auth_sock); 345 if (r != 0) { 346 error_r(r, "Could not get agent socket"); 347 have_agent = 0; 348 } 349 } 350 if (box != NULL) 351 ssh_sandbox_parent_preauth(box, pid); 352 monitor_child_preauth(ssh, pmonitor); 353 354 /* Wait for the child's exit status */ 355 while (waitpid(pid, &status, 0) == -1) { 356 if (errno == EINTR) 357 continue; 358 pmonitor->m_pid = -1; 359 fatal_f("waitpid: %s", strerror(errno)); 360 } 361 privsep_is_preauth = 0; 362 pmonitor->m_pid = -1; 363 if (WIFEXITED(status)) { 364 if (WEXITSTATUS(status) != 0) 365 fatal_f("preauth child exited with status %d", 366 WEXITSTATUS(status)); 367 } else if (WIFSIGNALED(status)) 368 fatal_f("preauth child terminated by signal %d", 369 WTERMSIG(status)); 370 if (box != NULL) 371 ssh_sandbox_parent_finish(box); 372 return 1; 373 } else { 374 /* child */ 375 close(pmonitor->m_sendfd); 376 close(pmonitor->m_log_recvfd); 377 378 /* Arrange for logging to be sent to the monitor */ 379 set_log_handler(mm_log_handler, pmonitor); 380 381 privsep_preauth_child(); 382 setproctitle("%s", "[net]"); 383 if (box != NULL) 384 ssh_sandbox_child(box); 385 386 return 0; 387 } 388 } 389 390 static void 391 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 392 { 393 int skip_privdrop = 0; 394 395 /* 396 * Hack for systems that don't support FD passing: retain privileges 397 * in the post-auth privsep process so it can allocate PTYs directly. 398 * This is basically equivalent to what we did <= 9.7, which was to 399 * disable post-auth privsep entriely. 400 * Cygwin doesn't need to drop privs here although it doesn't support 401 * fd passing, as AFAIK PTY allocation on this platform doesn't require 402 * special privileges to begin with. 403 */ 404 #if defined(DISABLE_FD_PASSING) && !defined(HAVE_CYGWIN) 405 skip_privdrop = 1; 406 #endif 407 408 /* New socket pair */ 409 monitor_reinit(pmonitor); 410 411 pmonitor->m_pid = fork(); 412 if (pmonitor->m_pid == -1) 413 fatal("fork of unprivileged child failed"); 414 else if (pmonitor->m_pid != 0) { 415 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 416 sshbuf_reset(loginmsg); 417 monitor_clear_keystate(ssh, pmonitor); 418 monitor_child_postauth(ssh, pmonitor); 419 420 /* NEVERREACHED */ 421 exit(0); 422 } 423 424 /* child */ 425 426 close(pmonitor->m_sendfd); 427 pmonitor->m_sendfd = -1; 428 429 /* Demote the private keys to public keys. */ 430 demote_sensitive_data(); 431 432 reseed_prngs(); 433 434 /* Drop privileges */ 435 if (!skip_privdrop) 436 do_setusercontext(authctxt->pw); 437 438 /* It is safe now to apply the key state */ 439 monitor_apply_keystate(ssh, pmonitor); 440 441 /* 442 * Tell the packet layer that authentication was successful, since 443 * this information is not part of the key state. 444 */ 445 ssh_packet_set_authenticated(ssh); 446 } 447 448 static void 449 append_hostkey_type(struct sshbuf *b, const char *s) 450 { 451 int r; 452 453 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 454 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 455 return; 456 } 457 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 458 fatal_fr(r, "sshbuf_putf"); 459 } 460 461 static char * 462 list_hostkey_types(void) 463 { 464 struct sshbuf *b; 465 struct sshkey *key; 466 char *ret; 467 u_int i; 468 469 if ((b = sshbuf_new()) == NULL) 470 fatal_f("sshbuf_new failed"); 471 for (i = 0; i < options.num_host_key_files; i++) { 472 key = sensitive_data.host_keys[i]; 473 if (key == NULL) 474 key = sensitive_data.host_pubkeys[i]; 475 if (key == NULL) 476 continue; 477 switch (key->type) { 478 case KEY_RSA: 479 /* for RSA we also support SHA2 signatures */ 480 append_hostkey_type(b, "rsa-sha2-512"); 481 append_hostkey_type(b, "rsa-sha2-256"); 482 /* FALLTHROUGH */ 483 case KEY_DSA: 484 case KEY_ECDSA: 485 case KEY_ED25519: 486 case KEY_ECDSA_SK: 487 case KEY_ED25519_SK: 488 case KEY_XMSS: 489 append_hostkey_type(b, sshkey_ssh_name(key)); 490 break; 491 } 492 /* If the private key has a cert peer, then list that too */ 493 key = sensitive_data.host_certificates[i]; 494 if (key == NULL) 495 continue; 496 switch (key->type) { 497 case KEY_RSA_CERT: 498 /* for RSA we also support SHA2 signatures */ 499 append_hostkey_type(b, 500 "rsa-sha2-512-cert-v01@openssh.com"); 501 append_hostkey_type(b, 502 "rsa-sha2-256-cert-v01@openssh.com"); 503 /* FALLTHROUGH */ 504 case KEY_DSA_CERT: 505 case KEY_ECDSA_CERT: 506 case KEY_ED25519_CERT: 507 case KEY_ECDSA_SK_CERT: 508 case KEY_ED25519_SK_CERT: 509 case KEY_XMSS_CERT: 510 append_hostkey_type(b, sshkey_ssh_name(key)); 511 break; 512 } 513 } 514 if ((ret = sshbuf_dup_string(b)) == NULL) 515 fatal_f("sshbuf_dup_string failed"); 516 sshbuf_free(b); 517 debug_f("%s", ret); 518 return ret; 519 } 520 521 static struct sshkey * 522 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 523 { 524 u_int i; 525 struct sshkey *key; 526 527 for (i = 0; i < options.num_host_key_files; i++) { 528 switch (type) { 529 case KEY_RSA_CERT: 530 case KEY_DSA_CERT: 531 case KEY_ECDSA_CERT: 532 case KEY_ED25519_CERT: 533 case KEY_ECDSA_SK_CERT: 534 case KEY_ED25519_SK_CERT: 535 case KEY_XMSS_CERT: 536 key = sensitive_data.host_certificates[i]; 537 break; 538 default: 539 key = sensitive_data.host_keys[i]; 540 if (key == NULL && !need_private) 541 key = sensitive_data.host_pubkeys[i]; 542 break; 543 } 544 if (key == NULL || key->type != type) 545 continue; 546 switch (type) { 547 case KEY_ECDSA: 548 case KEY_ECDSA_SK: 549 case KEY_ECDSA_CERT: 550 case KEY_ECDSA_SK_CERT: 551 if (key->ecdsa_nid != nid) 552 continue; 553 /* FALLTHROUGH */ 554 default: 555 return need_private ? 556 sensitive_data.host_keys[i] : key; 557 } 558 } 559 return NULL; 560 } 561 562 struct sshkey * 563 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 564 { 565 return get_hostkey_by_type(type, nid, 0, ssh); 566 } 567 568 struct sshkey * 569 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 570 { 571 return get_hostkey_by_type(type, nid, 1, ssh); 572 } 573 574 struct sshkey * 575 get_hostkey_by_index(int ind) 576 { 577 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 578 return (NULL); 579 return (sensitive_data.host_keys[ind]); 580 } 581 582 struct sshkey * 583 get_hostkey_public_by_index(int ind, struct ssh *ssh) 584 { 585 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 586 return (NULL); 587 return (sensitive_data.host_pubkeys[ind]); 588 } 589 590 int 591 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 592 { 593 u_int i; 594 595 for (i = 0; i < options.num_host_key_files; i++) { 596 if (sshkey_is_cert(key)) { 597 if (key == sensitive_data.host_certificates[i] || 598 (compare && sensitive_data.host_certificates[i] && 599 sshkey_equal(key, 600 sensitive_data.host_certificates[i]))) 601 return (i); 602 } else { 603 if (key == sensitive_data.host_keys[i] || 604 (compare && sensitive_data.host_keys[i] && 605 sshkey_equal(key, sensitive_data.host_keys[i]))) 606 return (i); 607 if (key == sensitive_data.host_pubkeys[i] || 608 (compare && sensitive_data.host_pubkeys[i] && 609 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 610 return (i); 611 } 612 } 613 return (-1); 614 } 615 616 /* Inform the client of all hostkeys */ 617 static void 618 notify_hostkeys(struct ssh *ssh) 619 { 620 struct sshbuf *buf; 621 struct sshkey *key; 622 u_int i, nkeys; 623 int r; 624 char *fp; 625 626 /* Some clients cannot cope with the hostkeys message, skip those. */ 627 if (ssh->compat & SSH_BUG_HOSTKEYS) 628 return; 629 630 if ((buf = sshbuf_new()) == NULL) 631 fatal_f("sshbuf_new"); 632 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 633 key = get_hostkey_public_by_index(i, ssh); 634 if (key == NULL || key->type == KEY_UNSPEC || 635 sshkey_is_cert(key)) 636 continue; 637 fp = sshkey_fingerprint(key, options.fingerprint_hash, 638 SSH_FP_DEFAULT); 639 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 640 free(fp); 641 if (nkeys == 0) { 642 /* 643 * Start building the request when we find the 644 * first usable key. 645 */ 646 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 647 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 648 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 649 sshpkt_fatal(ssh, r, "%s: start request", __func__); 650 } 651 /* Append the key to the request */ 652 sshbuf_reset(buf); 653 if ((r = sshkey_putb(key, buf)) != 0) 654 fatal_fr(r, "couldn't put hostkey %d", i); 655 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 656 sshpkt_fatal(ssh, r, "%s: append key", __func__); 657 nkeys++; 658 } 659 debug3_f("sent %u hostkeys", nkeys); 660 if (nkeys == 0) 661 fatal_f("no hostkeys"); 662 if ((r = sshpkt_send(ssh)) != 0) 663 sshpkt_fatal(ssh, r, "%s: send", __func__); 664 sshbuf_free(buf); 665 } 666 667 static void 668 usage(void) 669 { 670 fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION); 671 fprintf(stderr, 672 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 673 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 674 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 675 ); 676 exit(1); 677 } 678 679 static void 680 parse_hostkeys(struct sshbuf *hostkeys) 681 { 682 int r; 683 u_int num_keys = 0; 684 struct sshkey *k; 685 struct sshbuf *kbuf; 686 const u_char *cp; 687 size_t len; 688 689 while (sshbuf_len(hostkeys) != 0) { 690 if (num_keys > 2048) 691 fatal_f("too many hostkeys"); 692 sensitive_data.host_keys = xrecallocarray( 693 sensitive_data.host_keys, num_keys, num_keys + 1, 694 sizeof(*sensitive_data.host_pubkeys)); 695 sensitive_data.host_pubkeys = xrecallocarray( 696 sensitive_data.host_pubkeys, num_keys, num_keys + 1, 697 sizeof(*sensitive_data.host_pubkeys)); 698 sensitive_data.host_certificates = xrecallocarray( 699 sensitive_data.host_certificates, num_keys, num_keys + 1, 700 sizeof(*sensitive_data.host_certificates)); 701 /* private key */ 702 k = NULL; 703 if ((r = sshbuf_froms(hostkeys, &kbuf)) != 0) 704 fatal_fr(r, "extract privkey"); 705 if (sshbuf_len(kbuf) != 0 && 706 (r = sshkey_private_deserialize(kbuf, &k)) != 0) 707 fatal_fr(r, "parse pubkey"); 708 sensitive_data.host_keys[num_keys] = k; 709 sshbuf_free(kbuf); 710 if (k) 711 debug2_f("privkey %u: %s", num_keys, sshkey_ssh_name(k)); 712 /* public key */ 713 k = NULL; 714 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0) 715 fatal_fr(r, "extract pubkey"); 716 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0) 717 fatal_fr(r, "parse pubkey"); 718 sensitive_data.host_pubkeys[num_keys] = k; 719 if (k) 720 debug2_f("pubkey %u: %s", num_keys, sshkey_ssh_name(k)); 721 /* certificate */ 722 k = NULL; 723 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0) 724 fatal_fr(r, "extract pubkey"); 725 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0) 726 fatal_fr(r, "parse pubkey"); 727 sensitive_data.host_certificates[num_keys] = k; 728 if (k) 729 debug2_f("cert %u: %s", num_keys, sshkey_ssh_name(k)); 730 num_keys++; 731 } 732 sensitive_data.num_hostkeys = num_keys; 733 } 734 735 static void 736 recv_rexec_state(int fd, struct sshbuf *conf, uint64_t *timing_secretp) 737 { 738 struct sshbuf *m, *inc, *hostkeys; 739 u_char *cp, ver; 740 size_t len; 741 int r; 742 struct include_item *item; 743 744 debug3_f("entering fd = %d", fd); 745 746 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 747 fatal_f("sshbuf_new failed"); 748 if (ssh_msg_recv(fd, m) == -1) 749 fatal_f("ssh_msg_recv failed"); 750 if ((r = sshbuf_get_u8(m, &ver)) != 0) 751 fatal_fr(r, "parse version"); 752 if (ver != 0) 753 fatal_f("rexec version mismatch"); 754 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || /* XXX _direct */ 755 (r = sshbuf_get_u64(m, timing_secretp)) != 0 || 756 (r = sshbuf_froms(m, &hostkeys)) != 0 || 757 (r = sshbuf_get_stringb(m, inc)) != 0) 758 fatal_fr(r, "parse config"); 759 760 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 761 fatal_fr(r, "sshbuf_put"); 762 763 while (sshbuf_len(inc) != 0) { 764 item = xcalloc(1, sizeof(*item)); 765 if ((item->contents = sshbuf_new()) == NULL) 766 fatal_f("sshbuf_new failed"); 767 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 768 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 769 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 770 fatal_fr(r, "parse includes"); 771 TAILQ_INSERT_TAIL(&includes, item, entry); 772 } 773 774 parse_hostkeys(hostkeys); 775 776 free(cp); 777 sshbuf_free(m); 778 sshbuf_free(hostkeys); 779 sshbuf_free(inc); 780 781 debug3_f("done"); 782 } 783 784 /* 785 * If IP options are supported, make sure there are none (log and 786 * return an error if any are found). Basically we are worried about 787 * source routing; it can be used to pretend you are somebody 788 * (ip-address) you are not. That itself may be "almost acceptable" 789 * under certain circumstances, but rhosts authentication is useless 790 * if source routing is accepted. Notice also that if we just dropped 791 * source routing here, the other side could use IP spoofing to do 792 * rest of the interaction and could still bypass security. So we 793 * exit here if we detect any IP options. 794 */ 795 static void 796 check_ip_options(struct ssh *ssh) 797 { 798 #ifdef IP_OPTIONS 799 int sock_in = ssh_packet_get_connection_in(ssh); 800 struct sockaddr_storage from; 801 u_char opts[200]; 802 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 803 char text[sizeof(opts) * 3 + 1]; 804 805 memset(&from, 0, sizeof(from)); 806 if (getpeername(sock_in, (struct sockaddr *)&from, 807 &fromlen) == -1) 808 return; 809 if (from.ss_family != AF_INET) 810 return; 811 /* XXX IPv6 options? */ 812 813 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 814 &option_size) >= 0 && option_size != 0) { 815 text[0] = '\0'; 816 for (i = 0; i < option_size; i++) 817 snprintf(text + i*3, sizeof(text) - i*3, 818 " %2.2x", opts[i]); 819 fatal("Connection from %.100s port %d with IP opts: %.800s", 820 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 821 } 822 #endif /* IP_OPTIONS */ 823 } 824 825 /* Set the routing domain for this process */ 826 static void 827 set_process_rdomain(struct ssh *ssh, const char *name) 828 { 829 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 830 if (name == NULL) 831 return; /* default */ 832 833 if (strcmp(name, "%D") == 0) { 834 /* "expands" to routing domain of connection */ 835 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 836 return; 837 } 838 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 839 return sys_set_process_rdomain(name); 840 #elif defined(__OpenBSD__) 841 int rtable, ortable = getrtable(); 842 const char *errstr; 843 844 if (name == NULL) 845 return; /* default */ 846 847 if (strcmp(name, "%D") == 0) { 848 /* "expands" to routing domain of connection */ 849 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 850 return; 851 } 852 853 rtable = (int)strtonum(name, 0, 255, &errstr); 854 if (errstr != NULL) /* Shouldn't happen */ 855 fatal("Invalid routing domain \"%s\": %s", name, errstr); 856 if (rtable != ortable && setrtable(rtable) != 0) 857 fatal("Unable to set routing domain %d: %s", 858 rtable, strerror(errno)); 859 debug_f("set routing domain %d (was %d)", rtable, ortable); 860 #else /* defined(__OpenBSD__) */ 861 fatal("Unable to set routing domain: not supported in this platform"); 862 #endif 863 } 864 865 /* 866 * Main program for the daemon. 867 */ 868 int 869 main(int ac, char **av) 870 { 871 struct ssh *ssh = NULL; 872 extern char *optarg; 873 extern int optind; 874 int r, opt, on = 1, remote_port; 875 int sock_in = -1, sock_out = -1, rexeced_flag = 0, have_key = 0; 876 const char *remote_ip, *rdomain; 877 char *line, *laddr, *logfile = NULL; 878 u_int i; 879 u_int64_t ibytes, obytes; 880 mode_t new_umask; 881 Authctxt *authctxt; 882 struct connection_info *connection_info = NULL; 883 sigset_t sigmask; 884 uint64_t timing_secret = 0; 885 struct itimerval itv; 886 887 sigemptyset(&sigmask); 888 sigprocmask(SIG_SETMASK, &sigmask, NULL); 889 890 #ifdef HAVE_SECUREWARE 891 (void)set_auth_parameters(ac, av); 892 #endif 893 __progname = ssh_get_progname(av[0]); 894 895 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 896 saved_argc = ac; 897 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 898 for (i = 0; (int)i < ac; i++) 899 saved_argv[i] = xstrdup(av[i]); 900 saved_argv[i] = NULL; 901 902 #ifndef HAVE_SETPROCTITLE 903 /* Prepare for later setproctitle emulation */ 904 compat_init_setproctitle(ac, av); 905 av = saved_argv; 906 #endif 907 908 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 909 sanitise_stdfd(); 910 911 /* Initialize configuration options to their default values. */ 912 initialize_server_options(&options); 913 914 /* Parse command-line arguments. */ 915 while ((opt = getopt(ac, av, 916 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 917 switch (opt) { 918 case '4': 919 options.address_family = AF_INET; 920 break; 921 case '6': 922 options.address_family = AF_INET6; 923 break; 924 case 'f': 925 config_file_name = optarg; 926 break; 927 case 'c': 928 servconf_add_hostcert("[command-line]", 0, 929 &options, optarg); 930 break; 931 case 'd': 932 if (debug_flag == 0) { 933 debug_flag = 1; 934 options.log_level = SYSLOG_LEVEL_DEBUG1; 935 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 936 options.log_level++; 937 break; 938 case 'D': 939 /* ignore */ 940 break; 941 case 'E': 942 logfile = optarg; 943 /* FALLTHROUGH */ 944 case 'e': 945 log_stderr = 1; 946 break; 947 case 'i': 948 inetd_flag = 1; 949 break; 950 case 'r': 951 /* ignore */ 952 break; 953 case 'R': 954 rexeced_flag = 1; 955 break; 956 case 'Q': 957 /* ignored */ 958 break; 959 case 'q': 960 options.log_level = SYSLOG_LEVEL_QUIET; 961 break; 962 case 'b': 963 /* protocol 1, ignored */ 964 break; 965 case 'p': 966 options.ports_from_cmdline = 1; 967 if (options.num_ports >= MAX_PORTS) { 968 fprintf(stderr, "too many ports.\n"); 969 exit(1); 970 } 971 options.ports[options.num_ports++] = a2port(optarg); 972 if (options.ports[options.num_ports-1] <= 0) { 973 fprintf(stderr, "Bad port number.\n"); 974 exit(1); 975 } 976 break; 977 case 'g': 978 if ((options.login_grace_time = convtime(optarg)) == -1) { 979 fprintf(stderr, "Invalid login grace time.\n"); 980 exit(1); 981 } 982 break; 983 case 'k': 984 /* protocol 1, ignored */ 985 break; 986 case 'h': 987 servconf_add_hostkey("[command-line]", 0, 988 &options, optarg, 1); 989 break; 990 case 't': 991 case 'T': 992 case 'G': 993 fatal("test/dump modes not supported"); 994 break; 995 case 'C': 996 connection_info = server_get_connection_info(ssh, 0, 0); 997 if (parse_server_match_testspec(connection_info, 998 optarg) == -1) 999 exit(1); 1000 break; 1001 case 'u': 1002 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1003 if (utmp_len > HOST_NAME_MAX+1) { 1004 fprintf(stderr, "Invalid utmp length.\n"); 1005 exit(1); 1006 } 1007 break; 1008 case 'o': 1009 line = xstrdup(optarg); 1010 if (process_server_config_line(&options, line, 1011 "command-line", 0, NULL, NULL, &includes) != 0) 1012 exit(1); 1013 free(line); 1014 break; 1015 case 'V': 1016 fprintf(stderr, "%s, %s\n", 1017 SSH_RELEASE, SSH_OPENSSL_VERSION); 1018 exit(0); 1019 default: 1020 usage(); 1021 break; 1022 } 1023 } 1024 1025 /* Check that there are no remaining arguments. */ 1026 if (optind < ac) { 1027 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1028 exit(1); 1029 } 1030 1031 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1032 1033 if (!rexeced_flag) 1034 fatal("sshd-session should not be executed directly"); 1035 1036 closefrom(REEXEC_MIN_FREE_FD); 1037 1038 seed_rng(); 1039 1040 /* If requested, redirect the logs to the specified logfile. */ 1041 if (logfile != NULL) { 1042 char *cp, pid_s[32]; 1043 1044 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid()); 1045 cp = percent_expand(logfile, 1046 "p", pid_s, 1047 "P", "sshd-session", 1048 (char *)NULL); 1049 log_redirect_stderr_to(cp); 1050 free(cp); 1051 } 1052 1053 /* 1054 * Force logging to stderr until we have loaded the private host 1055 * key (unless started from inetd) 1056 */ 1057 log_init(__progname, 1058 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1059 SYSLOG_LEVEL_INFO : options.log_level, 1060 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1061 SYSLOG_FACILITY_AUTH : options.log_facility, 1062 log_stderr || !inetd_flag || debug_flag); 1063 1064 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1065 1066 /* Fetch our configuration */ 1067 if ((cfg = sshbuf_new()) == NULL) 1068 fatal("sshbuf_new config buf failed"); 1069 setproctitle("%s", "[rexeced]"); 1070 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg, &timing_secret); 1071 close(REEXEC_CONFIG_PASS_FD); 1072 parse_server_config(&options, "rexec", cfg, &includes, NULL, 1); 1073 /* Fill in default values for those options not explicitly set. */ 1074 fill_default_server_options(&options); 1075 options.timing_secret = timing_secret; 1076 1077 /* Store privilege separation user for later use if required. */ 1078 privsep_chroot = (getuid() == 0 || geteuid() == 0); 1079 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1080 if (privsep_chroot || options.kerberos_authentication) 1081 fatal("Privilege separation user %s does not exist", 1082 SSH_PRIVSEP_USER); 1083 } else { 1084 privsep_pw = pwcopy(privsep_pw); 1085 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1086 privsep_pw->pw_passwd = xstrdup("*"); 1087 } 1088 endpwent(); 1089 1090 if (!debug_flag) { 1091 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1092 close(REEXEC_STARTUP_PIPE_FD); 1093 /* 1094 * Signal parent that this child is at a point where 1095 * they can go away if they have a SIGHUP pending. 1096 */ 1097 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1098 } 1099 1100 /* Check that options are sensible */ 1101 if (options.authorized_keys_command_user == NULL && 1102 (options.authorized_keys_command != NULL && 1103 strcasecmp(options.authorized_keys_command, "none") != 0)) 1104 fatal("AuthorizedKeysCommand set without " 1105 "AuthorizedKeysCommandUser"); 1106 if (options.authorized_principals_command_user == NULL && 1107 (options.authorized_principals_command != NULL && 1108 strcasecmp(options.authorized_principals_command, "none") != 0)) 1109 fatal("AuthorizedPrincipalsCommand set without " 1110 "AuthorizedPrincipalsCommandUser"); 1111 1112 /* 1113 * Check whether there is any path through configured auth methods. 1114 * Unfortunately it is not possible to verify this generally before 1115 * daemonisation in the presence of Match block, but this catches 1116 * and warns for trivial misconfigurations that could break login. 1117 */ 1118 if (options.num_auth_methods != 0) { 1119 for (i = 0; i < options.num_auth_methods; i++) { 1120 if (auth2_methods_valid(options.auth_methods[i], 1121 1) == 0) 1122 break; 1123 } 1124 if (i >= options.num_auth_methods) 1125 fatal("AuthenticationMethods cannot be satisfied by " 1126 "enabled authentication methods"); 1127 } 1128 1129 #ifdef WITH_OPENSSL 1130 if (options.moduli_file != NULL) 1131 dh_set_moduli_file(options.moduli_file); 1132 #endif 1133 1134 if (options.host_key_agent) { 1135 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1136 setenv(SSH_AUTHSOCKET_ENV_NAME, 1137 options.host_key_agent, 1); 1138 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1139 have_agent = 1; 1140 else 1141 error_r(r, "Could not connect to agent \"%s\"", 1142 options.host_key_agent); 1143 } 1144 1145 if (options.num_host_key_files != sensitive_data.num_hostkeys) { 1146 fatal("internal error: hostkeys confused (config %u recvd %u)", 1147 options.num_host_key_files, sensitive_data.num_hostkeys); 1148 } 1149 1150 for (i = 0; i < options.num_host_key_files; i++) { 1151 if (sensitive_data.host_keys[i] != NULL || 1152 (have_agent && sensitive_data.host_pubkeys[i] != NULL)) { 1153 have_key = 1; 1154 break; 1155 } 1156 } 1157 if (!have_key) 1158 fatal("internal error: monitor received no hostkeys"); 1159 1160 /* Ensure that umask disallows at least group and world write */ 1161 new_umask = umask(0077) | 0022; 1162 (void) umask(new_umask); 1163 1164 /* Initialize the log (it is reinitialized below in case we forked). */ 1165 if (debug_flag) 1166 log_stderr = 1; 1167 log_init(__progname, options.log_level, 1168 options.log_facility, log_stderr); 1169 for (i = 0; i < options.num_log_verbose; i++) 1170 log_verbose_add(options.log_verbose[i]); 1171 1172 /* Reinitialize the log (because of the fork above). */ 1173 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1174 1175 /* 1176 * Chdir to the root directory so that the current disk can be 1177 * unmounted if desired. 1178 */ 1179 if (chdir("/") == -1) 1180 error("chdir(\"/\"): %s", strerror(errno)); 1181 1182 /* ignore SIGPIPE */ 1183 ssh_signal(SIGPIPE, SIG_IGN); 1184 1185 /* Get a connection, either from inetd or rexec */ 1186 if (inetd_flag) { 1187 /* 1188 * NB. must be different fd numbers for the !socket case, 1189 * as packet_connection_is_on_socket() depends on this. 1190 */ 1191 sock_in = dup(STDIN_FILENO); 1192 sock_out = dup(STDOUT_FILENO); 1193 } else { 1194 /* rexec case; accept()ed socket in ancestor listener */ 1195 sock_in = sock_out = dup(STDIN_FILENO); 1196 } 1197 1198 /* 1199 * We intentionally do not close the descriptors 0, 1, and 2 1200 * as our code for setting the descriptors won't work if 1201 * ttyfd happens to be one of those. 1202 */ 1203 if (stdfd_devnull(1, 1, !log_stderr) == -1) 1204 error("stdfd_devnull failed"); 1205 debug("network sockets: %d, %d", sock_in, sock_out); 1206 1207 /* This is the child processing a new connection. */ 1208 setproctitle("%s", "[accepted]"); 1209 1210 /* Executed child processes don't need these. */ 1211 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1212 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1213 1214 /* We will not restart on SIGHUP since it no longer makes sense. */ 1215 ssh_signal(SIGALRM, SIG_DFL); 1216 ssh_signal(SIGHUP, SIG_DFL); 1217 ssh_signal(SIGTERM, SIG_DFL); 1218 ssh_signal(SIGQUIT, SIG_DFL); 1219 ssh_signal(SIGCHLD, SIG_DFL); 1220 ssh_signal(SIGINT, SIG_DFL); 1221 1222 /* 1223 * Register our connection. This turns encryption off because we do 1224 * not have a key. 1225 */ 1226 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 1227 fatal("Unable to create connection"); 1228 the_active_state = ssh; 1229 ssh_packet_set_server(ssh); 1230 1231 check_ip_options(ssh); 1232 1233 /* Prepare the channels layer */ 1234 channel_init_channels(ssh); 1235 channel_set_af(ssh, options.address_family); 1236 server_process_channel_timeouts(ssh); 1237 server_process_permitopen(ssh); 1238 1239 /* Set SO_KEEPALIVE if requested. */ 1240 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 1241 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 1242 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1243 1244 if ((remote_port = ssh_remote_port(ssh)) < 0) { 1245 debug("ssh_remote_port failed"); 1246 cleanup_exit(255); 1247 } 1248 1249 #ifdef HAVE_LOGIN_CAP 1250 /* Also caches remote hostname for sandboxed child. */ 1251 auth_get_canonical_hostname(ssh, options.use_dns); 1252 #endif 1253 1254 /* 1255 * The rest of the code depends on the fact that 1256 * ssh_remote_ipaddr() caches the remote ip, even if 1257 * the socket goes away. 1258 */ 1259 remote_ip = ssh_remote_ipaddr(ssh); 1260 1261 #ifdef SSH_AUDIT_EVENTS 1262 audit_connection_from(remote_ip, remote_port); 1263 #endif 1264 1265 rdomain = ssh_packet_rdomain_in(ssh); 1266 1267 /* Log the connection. */ 1268 laddr = get_local_ipaddr(sock_in); 1269 verbose("Connection from %s port %d on %s port %d%s%s%s", 1270 remote_ip, remote_port, laddr, ssh_local_port(ssh), 1271 rdomain == NULL ? "" : " rdomain \"", 1272 rdomain == NULL ? "" : rdomain, 1273 rdomain == NULL ? "" : "\""); 1274 free(laddr); 1275 1276 /* 1277 * We don't want to listen forever unless the other side 1278 * successfully authenticates itself. So we set up an alarm which is 1279 * cleared after successful authentication. A limit of zero 1280 * indicates no limit. Note that we don't set the alarm in debugging 1281 * mode; it is just annoying to have the server exit just when you 1282 * are about to discover the bug. 1283 */ 1284 ssh_signal(SIGALRM, grace_alarm_handler); 1285 if (!debug_flag && options.login_grace_time > 0) { 1286 int ujitter = arc4random_uniform(4 * 1000000); 1287 1288 timerclear(&itv.it_interval); 1289 itv.it_value.tv_sec = options.login_grace_time; 1290 itv.it_value.tv_sec += ujitter / 1000000; 1291 itv.it_value.tv_usec = ujitter % 1000000; 1292 1293 if (setitimer(ITIMER_REAL, &itv, NULL) == -1) 1294 fatal("login grace time setitimer failed"); 1295 } 1296 1297 if ((r = kex_exchange_identification(ssh, -1, 1298 options.version_addendum)) != 0) 1299 sshpkt_fatal(ssh, r, "banner exchange"); 1300 1301 ssh_packet_set_nonblocking(ssh); 1302 1303 /* allocate authentication context */ 1304 authctxt = xcalloc(1, sizeof(*authctxt)); 1305 ssh->authctxt = authctxt; 1306 1307 /* XXX global for cleanup, access from other modules */ 1308 the_authctxt = authctxt; 1309 1310 /* Set default key authentication options */ 1311 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 1312 fatal("allocation failed"); 1313 1314 /* prepare buffer to collect messages to display to user after login */ 1315 if ((loginmsg = sshbuf_new()) == NULL) 1316 fatal("sshbuf_new loginmsg failed"); 1317 auth_debug_reset(); 1318 1319 if (privsep_preauth(ssh) == 1) 1320 goto authenticated; 1321 1322 /* perform the key exchange */ 1323 /* authenticate user and start session */ 1324 do_ssh2_kex(ssh); 1325 do_authentication2(ssh); 1326 1327 /* 1328 * The unprivileged child now transfers the current keystate and exits. 1329 */ 1330 mm_send_keystate(ssh, pmonitor); 1331 ssh_packet_clear_keys(ssh); 1332 exit(0); 1333 1334 authenticated: 1335 /* 1336 * Cancel the alarm we set to limit the time taken for 1337 * authentication. 1338 */ 1339 timerclear(&itv.it_interval); 1340 timerclear(&itv.it_value); 1341 if (setitimer(ITIMER_REAL, &itv, NULL) == -1) 1342 fatal("login grace time clear failed"); 1343 ssh_signal(SIGALRM, SIG_DFL); 1344 authctxt->authenticated = 1; 1345 if (startup_pipe != -1) { 1346 /* signal listener that authentication completed successfully */ 1347 (void)atomicio(vwrite, startup_pipe, "\001", 1); 1348 close(startup_pipe); 1349 startup_pipe = -1; 1350 } 1351 1352 if (options.routing_domain != NULL) 1353 set_process_rdomain(ssh, options.routing_domain); 1354 1355 #ifdef SSH_AUDIT_EVENTS 1356 audit_event(ssh, SSH_AUTH_SUCCESS); 1357 #endif 1358 1359 #ifdef GSSAPI 1360 if (options.gss_authentication) { 1361 temporarily_use_uid(authctxt->pw); 1362 ssh_gssapi_storecreds(); 1363 restore_uid(); 1364 } 1365 #endif 1366 #ifdef USE_PAM 1367 if (options.use_pam) { 1368 do_pam_setcred(); 1369 do_pam_session(ssh); 1370 } 1371 #endif 1372 1373 /* 1374 * In privilege separation, we fork another child and prepare 1375 * file descriptor passing. 1376 */ 1377 privsep_postauth(ssh, authctxt); 1378 /* the monitor process [priv] will not return */ 1379 1380 ssh_packet_set_timeout(ssh, options.client_alive_interval, 1381 options.client_alive_count_max); 1382 1383 /* Try to send all our hostkeys to the client */ 1384 notify_hostkeys(ssh); 1385 1386 /* Start session. */ 1387 do_authenticated(ssh, authctxt); 1388 1389 /* The connection has been terminated. */ 1390 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 1391 verbose("Transferred: sent %llu, received %llu bytes", 1392 (unsigned long long)obytes, (unsigned long long)ibytes); 1393 1394 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1395 1396 #ifdef USE_PAM 1397 if (options.use_pam) 1398 finish_pam(); 1399 #endif /* USE_PAM */ 1400 1401 #ifdef SSH_AUDIT_EVENTS 1402 mm_audit_event(ssh, SSH_CONNECTION_CLOSE); 1403 #endif 1404 1405 ssh_packet_close(ssh); 1406 1407 mm_terminate(); 1408 1409 exit(0); 1410 } 1411 1412 int 1413 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 1414 struct sshkey *pubkey, u_char **signature, size_t *slenp, 1415 const u_char *data, size_t dlen, const char *alg) 1416 { 1417 if (privkey) { 1418 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 1419 data, dlen, alg, options.sk_provider, NULL, 1420 ssh->compat) < 0) 1421 fatal_f("privkey sign failed"); 1422 } else { 1423 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 1424 data, dlen, alg, options.sk_provider, NULL, 1425 ssh->compat) < 0) 1426 fatal_f("pubkey sign failed"); 1427 } 1428 return 0; 1429 } 1430 1431 /* SSH2 key exchange */ 1432 static void 1433 do_ssh2_kex(struct ssh *ssh) 1434 { 1435 char *hkalgs = NULL, *myproposal[PROPOSAL_MAX]; 1436 const char *compression = NULL; 1437 struct kex *kex; 1438 int r; 1439 1440 if (options.rekey_limit || options.rekey_interval) 1441 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 1442 options.rekey_interval); 1443 1444 if (options.compression == COMP_NONE) 1445 compression = "none"; 1446 hkalgs = list_hostkey_types(); 1447 1448 kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms, 1449 options.ciphers, options.macs, compression, hkalgs); 1450 1451 free(hkalgs); 1452 1453 /* start key exchange */ 1454 if ((r = kex_setup(ssh, myproposal)) != 0) 1455 fatal_r(r, "kex_setup"); 1456 kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos); 1457 kex = ssh->kex; 1458 1459 #ifdef WITH_OPENSSL 1460 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1461 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1462 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1463 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1464 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1465 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1466 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1467 #ifdef OPENSSL_HAS_ECC 1468 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1469 #endif 1470 #endif 1471 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1472 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1473 kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server; 1474 kex->load_host_public_key=&get_hostkey_public_by_type; 1475 kex->load_host_private_key=&get_hostkey_private_by_type; 1476 kex->host_key_index=&get_hostkey_index; 1477 kex->sign = sshd_hostkey_sign; 1478 1479 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 1480 kex_proposal_free_entries(myproposal); 1481 1482 #ifdef DEBUG_KEXDH 1483 /* send 1st encrypted/maced/compressed message */ 1484 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 1485 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 1486 (r = sshpkt_send(ssh)) != 0 || 1487 (r = ssh_packet_write_wait(ssh)) != 0) 1488 fatal_fr(r, "send test"); 1489 #endif 1490 debug("KEX done"); 1491 } 1492 1493 /* server specific fatal cleanup */ 1494 void 1495 cleanup_exit(int i) 1496 { 1497 extern int auth_attempted; /* monitor.c */ 1498 1499 if (the_active_state != NULL && the_authctxt != NULL) { 1500 do_cleanup(the_active_state, the_authctxt); 1501 if (privsep_is_preauth && 1502 pmonitor != NULL && pmonitor->m_pid > 1) { 1503 debug("Killing privsep child %d", pmonitor->m_pid); 1504 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 1505 errno != ESRCH) { 1506 error_f("kill(%d): %s", pmonitor->m_pid, 1507 strerror(errno)); 1508 } 1509 } 1510 } 1511 #ifdef SSH_AUDIT_EVENTS 1512 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 1513 if (the_active_state != NULL && mm_is_monitor()) 1514 audit_event(the_active_state, SSH_CONNECTION_ABANDON); 1515 #endif 1516 /* Override default fatal exit value when auth was attempted */ 1517 if (i == 255 && auth_attempted) 1518 _exit(EXIT_AUTH_ATTEMPTED); 1519 _exit(i); 1520 } 1521