sshconnect2.c revision 1.1.1.14
1 /* $OpenBSD: sshconnect2.c,v 1.247 2016/07/22 05:46:11 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "hostfile.h" 67 #include "ssherr.h" 68 #include "utf8.h" 69 70 #ifdef GSSAPI 71 #include "ssh-gss.h" 72 #endif 73 74 /* import */ 75 extern char *client_version_string; 76 extern char *server_version_string; 77 extern Options options; 78 79 /* 80 * SSH2 key exchange 81 */ 82 83 u_char *session_id2 = NULL; 84 u_int session_id2_len = 0; 85 86 char *xxx_host; 87 struct sockaddr *xxx_hostaddr; 88 89 static int 90 verify_host_key_callback(Key *hostkey, struct ssh *ssh) 91 { 92 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 93 fatal("Host key verification failed."); 94 return 0; 95 } 96 97 static char * 98 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 99 { 100 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 101 size_t maxlen; 102 struct hostkeys *hostkeys; 103 int ktype; 104 u_int i; 105 106 /* Find all hostkeys for this hostname */ 107 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 108 hostkeys = init_hostkeys(); 109 for (i = 0; i < options.num_user_hostfiles; i++) 110 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 111 for (i = 0; i < options.num_system_hostfiles; i++) 112 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 113 114 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 115 maxlen = strlen(avail) + 1; 116 first = xmalloc(maxlen); 117 last = xmalloc(maxlen); 118 *first = *last = '\0'; 119 120 #define ALG_APPEND(to, from) \ 121 do { \ 122 if (*to != '\0') \ 123 strlcat(to, ",", maxlen); \ 124 strlcat(to, from, maxlen); \ 125 } while (0) 126 127 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 128 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 129 fatal("%s: unknown alg %s", __func__, alg); 130 if (lookup_key_in_hostkeys_by_type(hostkeys, 131 sshkey_type_plain(ktype), NULL)) 132 ALG_APPEND(first, alg); 133 else 134 ALG_APPEND(last, alg); 135 } 136 #undef ALG_APPEND 137 xasprintf(&ret, "%s%s%s", first, 138 (*first == '\0' || *last == '\0') ? "" : ",", last); 139 if (*first != '\0') 140 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 141 142 free(first); 143 free(last); 144 free(hostname); 145 free(oavail); 146 free_hostkeys(hostkeys); 147 148 return ret; 149 } 150 151 void 152 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 153 { 154 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 155 char *s; 156 struct kex *kex; 157 int r; 158 159 xxx_host = host; 160 xxx_hostaddr = hostaddr; 161 162 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 163 fatal("%s: kex_names_cat", __func__); 164 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 165 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 166 compat_cipher_proposal(options.ciphers); 167 myproposal[PROPOSAL_ENC_ALGS_STOC] = 168 compat_cipher_proposal(options.ciphers); 169 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 170 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 171 "zlib (at) openssh.com,zlib,none" : "none,zlib (at) openssh.com,zlib"; 172 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 173 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 174 if (options.hostkeyalgorithms != NULL) { 175 if (kex_assemble_names(KEX_DEFAULT_PK_ALG, 176 &options.hostkeyalgorithms) != 0) 177 fatal("%s: kex_assemble_namelist", __func__); 178 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 179 compat_pkalg_proposal(options.hostkeyalgorithms); 180 } else { 181 /* Enforce default */ 182 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 183 /* Prefer algorithms that we already have keys for */ 184 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 185 compat_pkalg_proposal( 186 order_hostkeyalgs(host, hostaddr, port)); 187 } 188 189 if (options.rekey_limit || options.rekey_interval) 190 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 191 (time_t)options.rekey_interval); 192 193 /* start key exchange */ 194 if ((r = kex_setup(active_state, myproposal)) != 0) 195 fatal("kex_setup: %s", ssh_err(r)); 196 kex = active_state->kex; 197 #ifdef WITH_OPENSSL 198 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 199 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 200 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 201 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 202 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 203 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 204 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 205 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 206 #endif 207 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 208 kex->client_version_string=client_version_string; 209 kex->server_version_string=server_version_string; 210 kex->verify_host_key=&verify_host_key_callback; 211 212 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 213 214 /* remove ext-info from the KEX proposals for rekeying */ 215 myproposal[PROPOSAL_KEX_ALGS] = 216 compat_kex_proposal(options.kex_algorithms); 217 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 218 fatal("kex_prop2buf: %s", ssh_err(r)); 219 220 session_id2 = kex->session_id; 221 session_id2_len = kex->session_id_len; 222 223 #ifdef DEBUG_KEXDH 224 /* send 1st encrypted/maced/compressed message */ 225 packet_start(SSH2_MSG_IGNORE); 226 packet_put_cstring("markus"); 227 packet_send(); 228 packet_write_wait(); 229 #endif 230 } 231 232 /* 233 * Authenticate user 234 */ 235 236 typedef struct cauthctxt Authctxt; 237 typedef struct cauthmethod Authmethod; 238 typedef struct identity Identity; 239 typedef struct idlist Idlist; 240 241 struct identity { 242 TAILQ_ENTRY(identity) next; 243 int agent_fd; /* >=0 if agent supports key */ 244 struct sshkey *key; /* public/private key */ 245 char *filename; /* comment for agent-only keys */ 246 int tried; 247 int isprivate; /* key points to the private key */ 248 int userprovided; 249 }; 250 TAILQ_HEAD(idlist, identity); 251 252 struct cauthctxt { 253 const char *server_user; 254 const char *local_user; 255 const char *host; 256 const char *service; 257 struct cauthmethod *method; 258 sig_atomic_t success; 259 char *authlist; 260 int attempt; 261 /* pubkey */ 262 struct idlist keys; 263 int agent_fd; 264 /* hostbased */ 265 Sensitive *sensitive; 266 char *oktypes, *ktypes; 267 const char *active_ktype; 268 /* kbd-interactive */ 269 int info_req_seen; 270 /* generic */ 271 void *methoddata; 272 }; 273 274 struct cauthmethod { 275 char *name; /* string to compare against server's list */ 276 int (*userauth)(Authctxt *authctxt); 277 void (*cleanup)(Authctxt *authctxt); 278 int *enabled; /* flag in option struct that enables method */ 279 int *batch_flag; /* flag in option struct that disables method */ 280 }; 281 282 int input_userauth_service_accept(int, u_int32_t, void *); 283 int input_userauth_ext_info(int, u_int32_t, void *); 284 int input_userauth_success(int, u_int32_t, void *); 285 int input_userauth_success_unexpected(int, u_int32_t, void *); 286 int input_userauth_failure(int, u_int32_t, void *); 287 int input_userauth_banner(int, u_int32_t, void *); 288 int input_userauth_error(int, u_int32_t, void *); 289 int input_userauth_info_req(int, u_int32_t, void *); 290 int input_userauth_pk_ok(int, u_int32_t, void *); 291 int input_userauth_passwd_changereq(int, u_int32_t, void *); 292 293 int userauth_none(Authctxt *); 294 int userauth_pubkey(Authctxt *); 295 int userauth_passwd(Authctxt *); 296 int userauth_kbdint(Authctxt *); 297 int userauth_hostbased(Authctxt *); 298 299 #ifdef GSSAPI 300 int userauth_gssapi(Authctxt *authctxt); 301 int input_gssapi_response(int type, u_int32_t, void *); 302 int input_gssapi_token(int type, u_int32_t, void *); 303 int input_gssapi_hash(int type, u_int32_t, void *); 304 int input_gssapi_error(int, u_int32_t, void *); 305 int input_gssapi_errtok(int, u_int32_t, void *); 306 #endif 307 308 void userauth(Authctxt *, char *); 309 310 static int sign_and_send_pubkey(Authctxt *, Identity *); 311 static void pubkey_prepare(Authctxt *); 312 static void pubkey_cleanup(Authctxt *); 313 static Key *load_identity_file(Identity *); 314 315 static Authmethod *authmethod_get(char *authlist); 316 static Authmethod *authmethod_lookup(const char *name); 317 static char *authmethods_get(void); 318 319 Authmethod authmethods[] = { 320 #ifdef GSSAPI 321 {"gssapi-with-mic", 322 userauth_gssapi, 323 NULL, 324 &options.gss_authentication, 325 NULL}, 326 #endif 327 {"hostbased", 328 userauth_hostbased, 329 NULL, 330 &options.hostbased_authentication, 331 NULL}, 332 {"publickey", 333 userauth_pubkey, 334 NULL, 335 &options.pubkey_authentication, 336 NULL}, 337 {"keyboard-interactive", 338 userauth_kbdint, 339 NULL, 340 &options.kbd_interactive_authentication, 341 &options.batch_mode}, 342 {"password", 343 userauth_passwd, 344 NULL, 345 &options.password_authentication, 346 &options.batch_mode}, 347 {"none", 348 userauth_none, 349 NULL, 350 NULL, 351 NULL}, 352 {NULL, NULL, NULL, NULL, NULL} 353 }; 354 355 void 356 ssh_userauth2(const char *local_user, const char *server_user, char *host, 357 Sensitive *sensitive) 358 { 359 struct ssh *ssh = active_state; 360 Authctxt authctxt; 361 int r; 362 363 if (options.challenge_response_authentication) 364 options.kbd_interactive_authentication = 1; 365 if (options.preferred_authentications == NULL) 366 options.preferred_authentications = authmethods_get(); 367 368 /* setup authentication context */ 369 memset(&authctxt, 0, sizeof(authctxt)); 370 pubkey_prepare(&authctxt); 371 authctxt.server_user = server_user; 372 authctxt.local_user = local_user; 373 authctxt.host = host; 374 authctxt.service = "ssh-connection"; /* service name */ 375 authctxt.success = 0; 376 authctxt.method = authmethod_lookup("none"); 377 authctxt.authlist = NULL; 378 authctxt.methoddata = NULL; 379 authctxt.sensitive = sensitive; 380 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 381 authctxt.info_req_seen = 0; 382 authctxt.agent_fd = -1; 383 if (authctxt.method == NULL) 384 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 385 386 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 387 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 388 (r = sshpkt_send(ssh)) != 0) 389 fatal("%s: %s", __func__, ssh_err(r)); 390 391 ssh_dispatch_init(ssh, &input_userauth_error); 392 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 393 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 394 ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 395 396 pubkey_cleanup(&authctxt); 397 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 398 399 debug("Authentication succeeded (%s).", authctxt.method->name); 400 } 401 402 /* ARGSUSED */ 403 int 404 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt) 405 { 406 Authctxt *authctxt = ctxt; 407 struct ssh *ssh = active_state; 408 int r; 409 410 if (ssh_packet_remaining(ssh) > 0) { 411 char *reply; 412 413 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 414 goto out; 415 debug2("service_accept: %s", reply); 416 free(reply); 417 } else { 418 debug2("buggy server: service_accept w/o service"); 419 } 420 if ((r = sshpkt_get_end(ssh)) != 0) 421 goto out; 422 debug("SSH2_MSG_SERVICE_ACCEPT received"); 423 424 /* initial userauth request */ 425 userauth_none(authctxt); 426 427 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 428 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 429 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 430 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 431 r = 0; 432 out: 433 return r; 434 } 435 436 /* ARGSUSED */ 437 int 438 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt) 439 { 440 return kex_input_ext_info(type, seqnr, active_state); 441 } 442 443 void 444 userauth(Authctxt *authctxt, char *authlist) 445 { 446 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 447 authctxt->method->cleanup(authctxt); 448 449 free(authctxt->methoddata); 450 authctxt->methoddata = NULL; 451 if (authlist == NULL) { 452 authlist = authctxt->authlist; 453 } else { 454 free(authctxt->authlist); 455 authctxt->authlist = authlist; 456 } 457 for (;;) { 458 Authmethod *method = authmethod_get(authlist); 459 if (method == NULL) 460 fatal("Permission denied (%s).", authlist); 461 authctxt->method = method; 462 463 /* reset the per method handler */ 464 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 465 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 466 467 /* and try new method */ 468 if (method->userauth(authctxt) != 0) { 469 debug2("we sent a %s packet, wait for reply", method->name); 470 break; 471 } else { 472 debug2("we did not send a packet, disable method"); 473 method->enabled = NULL; 474 } 475 } 476 } 477 478 /* ARGSUSED */ 479 int 480 input_userauth_error(int type, u_int32_t seq, void *ctxt) 481 { 482 fatal("input_userauth_error: bad message during authentication: " 483 "type %d", type); 484 return 0; 485 } 486 487 /* ARGSUSED */ 488 int 489 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 490 { 491 char *msg, *lang; 492 u_int len; 493 494 debug3("%s", __func__); 495 msg = packet_get_string(&len); 496 lang = packet_get_string(NULL); 497 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 498 fmprintf(stderr, "%s", msg); 499 free(msg); 500 free(lang); 501 return 0; 502 } 503 504 /* ARGSUSED */ 505 int 506 input_userauth_success(int type, u_int32_t seq, void *ctxt) 507 { 508 Authctxt *authctxt = ctxt; 509 510 if (authctxt == NULL) 511 fatal("input_userauth_success: no authentication context"); 512 free(authctxt->authlist); 513 authctxt->authlist = NULL; 514 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 515 authctxt->method->cleanup(authctxt); 516 free(authctxt->methoddata); 517 authctxt->methoddata = NULL; 518 authctxt->success = 1; /* break out */ 519 return 0; 520 } 521 522 int 523 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 524 { 525 Authctxt *authctxt = ctxt; 526 527 if (authctxt == NULL) 528 fatal("%s: no authentication context", __func__); 529 530 fatal("Unexpected authentication success during %s.", 531 authctxt->method->name); 532 return 0; 533 } 534 535 /* ARGSUSED */ 536 int 537 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 538 { 539 Authctxt *authctxt = ctxt; 540 char *authlist = NULL; 541 int partial; 542 543 if (authctxt == NULL) 544 fatal("input_userauth_failure: no authentication context"); 545 546 authlist = packet_get_string(NULL); 547 partial = packet_get_char(); 548 packet_check_eom(); 549 550 if (partial != 0) { 551 verbose("Authenticated with partial success."); 552 /* reset state */ 553 pubkey_cleanup(authctxt); 554 pubkey_prepare(authctxt); 555 } 556 debug("Authentications that can continue: %s", authlist); 557 558 userauth(authctxt, authlist); 559 return 0; 560 } 561 562 /* ARGSUSED */ 563 int 564 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 565 { 566 Authctxt *authctxt = ctxt; 567 Key *key = NULL; 568 Identity *id = NULL; 569 Buffer b; 570 int pktype, sent = 0; 571 u_int alen, blen; 572 char *pkalg, *fp; 573 u_char *pkblob; 574 575 if (authctxt == NULL) 576 fatal("input_userauth_pk_ok: no authentication context"); 577 if (datafellows & SSH_BUG_PKOK) { 578 /* this is similar to SSH_BUG_PKAUTH */ 579 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 580 pkblob = packet_get_string(&blen); 581 buffer_init(&b); 582 buffer_append(&b, pkblob, blen); 583 pkalg = buffer_get_string(&b, &alen); 584 buffer_free(&b); 585 } else { 586 pkalg = packet_get_string(&alen); 587 pkblob = packet_get_string(&blen); 588 } 589 packet_check_eom(); 590 591 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 592 593 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 594 debug("unknown pkalg %s", pkalg); 595 goto done; 596 } 597 if ((key = key_from_blob(pkblob, blen)) == NULL) { 598 debug("no key from blob. pkalg %s", pkalg); 599 goto done; 600 } 601 if (key->type != pktype) { 602 error("input_userauth_pk_ok: type mismatch " 603 "for decoded key (received %d, expected %d)", 604 key->type, pktype); 605 goto done; 606 } 607 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 608 SSH_FP_DEFAULT)) == NULL) 609 goto done; 610 debug2("input_userauth_pk_ok: fp %s", fp); 611 free(fp); 612 613 /* 614 * search keys in the reverse order, because last candidate has been 615 * moved to the end of the queue. this also avoids confusion by 616 * duplicate keys 617 */ 618 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 619 if (key_equal(key, id->key)) { 620 sent = sign_and_send_pubkey(authctxt, id); 621 break; 622 } 623 } 624 done: 625 if (key != NULL) 626 key_free(key); 627 free(pkalg); 628 free(pkblob); 629 630 /* try another method if we did not send a packet */ 631 if (sent == 0) 632 userauth(authctxt, NULL); 633 return 0; 634 } 635 636 #ifdef GSSAPI 637 int 638 userauth_gssapi(Authctxt *authctxt) 639 { 640 Gssctxt *gssctxt = NULL; 641 static gss_OID_set gss_supported = NULL; 642 static u_int mech = 0; 643 OM_uint32 min; 644 int ok = 0; 645 646 /* Try one GSSAPI method at a time, rather than sending them all at 647 * once. */ 648 649 if (gss_supported == NULL) 650 gss_indicate_mechs(&min, &gss_supported); 651 652 /* Check to see if the mechanism is usable before we offer it */ 653 while (mech < gss_supported->count && !ok) { 654 /* My DER encoding requires length<128 */ 655 if (gss_supported->elements[mech].length < 128 && 656 ssh_gssapi_check_mechanism(&gssctxt, 657 &gss_supported->elements[mech], authctxt->host)) { 658 ok = 1; /* Mechanism works */ 659 } else { 660 mech++; 661 } 662 } 663 664 if (!ok) 665 return 0; 666 667 authctxt->methoddata=(void *)gssctxt; 668 669 packet_start(SSH2_MSG_USERAUTH_REQUEST); 670 packet_put_cstring(authctxt->server_user); 671 packet_put_cstring(authctxt->service); 672 packet_put_cstring(authctxt->method->name); 673 674 packet_put_int(1); 675 676 packet_put_int((gss_supported->elements[mech].length) + 2); 677 packet_put_char(SSH_GSS_OIDTYPE); 678 packet_put_char(gss_supported->elements[mech].length); 679 packet_put_raw(gss_supported->elements[mech].elements, 680 gss_supported->elements[mech].length); 681 682 packet_send(); 683 684 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 685 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 686 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 687 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 688 689 mech++; /* Move along to next candidate */ 690 691 return 1; 692 } 693 694 static OM_uint32 695 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 696 { 697 Authctxt *authctxt = ctxt; 698 Gssctxt *gssctxt = authctxt->methoddata; 699 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 700 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 701 gss_buffer_desc gssbuf; 702 OM_uint32 status, ms, flags; 703 Buffer b; 704 705 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 706 recv_tok, &send_tok, &flags); 707 708 if (send_tok.length > 0) { 709 if (GSS_ERROR(status)) 710 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 711 else 712 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 713 714 packet_put_string(send_tok.value, send_tok.length); 715 packet_send(); 716 gss_release_buffer(&ms, &send_tok); 717 } 718 719 if (status == GSS_S_COMPLETE) { 720 /* send either complete or MIC, depending on mechanism */ 721 if (!(flags & GSS_C_INTEG_FLAG)) { 722 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 723 packet_send(); 724 } else { 725 ssh_gssapi_buildmic(&b, authctxt->server_user, 726 authctxt->service, "gssapi-with-mic"); 727 728 gssbuf.value = buffer_ptr(&b); 729 gssbuf.length = buffer_len(&b); 730 731 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 732 733 if (!GSS_ERROR(status)) { 734 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 735 packet_put_string(mic.value, mic.length); 736 737 packet_send(); 738 } 739 740 buffer_free(&b); 741 gss_release_buffer(&ms, &mic); 742 } 743 } 744 745 return status; 746 } 747 748 /* ARGSUSED */ 749 int 750 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 751 { 752 Authctxt *authctxt = ctxt; 753 Gssctxt *gssctxt; 754 int oidlen; 755 char *oidv; 756 757 if (authctxt == NULL) 758 fatal("input_gssapi_response: no authentication context"); 759 gssctxt = authctxt->methoddata; 760 761 /* Setup our OID */ 762 oidv = packet_get_string(&oidlen); 763 764 if (oidlen <= 2 || 765 oidv[0] != SSH_GSS_OIDTYPE || 766 oidv[1] != oidlen - 2) { 767 free(oidv); 768 debug("Badly encoded mechanism OID received"); 769 userauth(authctxt, NULL); 770 return 0; 771 } 772 773 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 774 fatal("Server returned different OID than expected"); 775 776 packet_check_eom(); 777 778 free(oidv); 779 780 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 781 /* Start again with next method on list */ 782 debug("Trying to start again"); 783 userauth(authctxt, NULL); 784 return 0; 785 } 786 return 0; 787 } 788 789 /* ARGSUSED */ 790 int 791 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 792 { 793 Authctxt *authctxt = ctxt; 794 gss_buffer_desc recv_tok; 795 OM_uint32 status; 796 u_int slen; 797 798 if (authctxt == NULL) 799 fatal("input_gssapi_response: no authentication context"); 800 801 recv_tok.value = packet_get_string(&slen); 802 recv_tok.length = slen; /* safe typecast */ 803 804 packet_check_eom(); 805 806 status = process_gssapi_token(ctxt, &recv_tok); 807 808 free(recv_tok.value); 809 810 if (GSS_ERROR(status)) { 811 /* Start again with the next method in the list */ 812 userauth(authctxt, NULL); 813 return 0; 814 } 815 return 0; 816 } 817 818 /* ARGSUSED */ 819 int 820 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 821 { 822 Authctxt *authctxt = ctxt; 823 Gssctxt *gssctxt; 824 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 825 gss_buffer_desc recv_tok; 826 OM_uint32 ms; 827 u_int len; 828 829 if (authctxt == NULL) 830 fatal("input_gssapi_response: no authentication context"); 831 gssctxt = authctxt->methoddata; 832 833 recv_tok.value = packet_get_string(&len); 834 recv_tok.length = len; 835 836 packet_check_eom(); 837 838 /* Stick it into GSSAPI and see what it says */ 839 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 840 &recv_tok, &send_tok, NULL); 841 842 free(recv_tok.value); 843 gss_release_buffer(&ms, &send_tok); 844 845 /* Server will be returning a failed packet after this one */ 846 return 0; 847 } 848 849 /* ARGSUSED */ 850 int 851 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 852 { 853 char *msg; 854 char *lang; 855 856 /* maj */(void)packet_get_int(); 857 /* min */(void)packet_get_int(); 858 msg=packet_get_string(NULL); 859 lang=packet_get_string(NULL); 860 861 packet_check_eom(); 862 863 debug("Server GSSAPI Error:\n%s", msg); 864 free(msg); 865 free(lang); 866 return 0; 867 } 868 #endif /* GSSAPI */ 869 870 int 871 userauth_none(Authctxt *authctxt) 872 { 873 /* initial userauth request */ 874 packet_start(SSH2_MSG_USERAUTH_REQUEST); 875 packet_put_cstring(authctxt->server_user); 876 packet_put_cstring(authctxt->service); 877 packet_put_cstring(authctxt->method->name); 878 packet_send(); 879 return 1; 880 } 881 882 int 883 userauth_passwd(Authctxt *authctxt) 884 { 885 static int attempt = 0; 886 char prompt[150]; 887 char *password; 888 const char *host = options.host_key_alias ? options.host_key_alias : 889 authctxt->host; 890 891 if (attempt++ >= options.number_of_password_prompts) 892 return 0; 893 894 if (attempt != 1) 895 error("Permission denied, please try again."); 896 897 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 898 authctxt->server_user, host); 899 password = read_passphrase(prompt, 0); 900 packet_start(SSH2_MSG_USERAUTH_REQUEST); 901 packet_put_cstring(authctxt->server_user); 902 packet_put_cstring(authctxt->service); 903 packet_put_cstring(authctxt->method->name); 904 packet_put_char(0); 905 packet_put_cstring(password); 906 explicit_bzero(password, strlen(password)); 907 free(password); 908 packet_add_padding(64); 909 packet_send(); 910 911 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 912 &input_userauth_passwd_changereq); 913 914 return 1; 915 } 916 917 /* 918 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 919 */ 920 /* ARGSUSED */ 921 int 922 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 923 { 924 Authctxt *authctxt = ctxt; 925 char *info, *lang, *password = NULL, *retype = NULL; 926 char prompt[150]; 927 const char *host = options.host_key_alias ? options.host_key_alias : 928 authctxt->host; 929 930 debug2("input_userauth_passwd_changereq"); 931 932 if (authctxt == NULL) 933 fatal("input_userauth_passwd_changereq: " 934 "no authentication context"); 935 936 info = packet_get_string(NULL); 937 lang = packet_get_string(NULL); 938 if (strlen(info) > 0) 939 logit("%s", info); 940 free(info); 941 free(lang); 942 packet_start(SSH2_MSG_USERAUTH_REQUEST); 943 packet_put_cstring(authctxt->server_user); 944 packet_put_cstring(authctxt->service); 945 packet_put_cstring(authctxt->method->name); 946 packet_put_char(1); /* additional info */ 947 snprintf(prompt, sizeof(prompt), 948 "Enter %.30s@%.128s's old password: ", 949 authctxt->server_user, host); 950 password = read_passphrase(prompt, 0); 951 packet_put_cstring(password); 952 explicit_bzero(password, strlen(password)); 953 free(password); 954 password = NULL; 955 while (password == NULL) { 956 snprintf(prompt, sizeof(prompt), 957 "Enter %.30s@%.128s's new password: ", 958 authctxt->server_user, host); 959 password = read_passphrase(prompt, RP_ALLOW_EOF); 960 if (password == NULL) { 961 /* bail out */ 962 return 0; 963 } 964 snprintf(prompt, sizeof(prompt), 965 "Retype %.30s@%.128s's new password: ", 966 authctxt->server_user, host); 967 retype = read_passphrase(prompt, 0); 968 if (strcmp(password, retype) != 0) { 969 explicit_bzero(password, strlen(password)); 970 free(password); 971 logit("Mismatch; try again, EOF to quit."); 972 password = NULL; 973 } 974 explicit_bzero(retype, strlen(retype)); 975 free(retype); 976 } 977 packet_put_cstring(password); 978 explicit_bzero(password, strlen(password)); 979 free(password); 980 packet_add_padding(64); 981 packet_send(); 982 983 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 984 &input_userauth_passwd_changereq); 985 return 0; 986 } 987 988 static const char * 989 identity_sign_encode(struct identity *id) 990 { 991 struct ssh *ssh = active_state; 992 993 if (id->key->type == KEY_RSA) { 994 switch (ssh->kex->rsa_sha2) { 995 case 256: 996 return "rsa-sha2-256"; 997 case 512: 998 return "rsa-sha2-512"; 999 } 1000 } 1001 return key_ssh_name(id->key); 1002 } 1003 1004 static int 1005 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1006 const u_char *data, size_t datalen, u_int compat) 1007 { 1008 Key *prv; 1009 int ret; 1010 const char *alg; 1011 1012 alg = identity_sign_encode(id); 1013 1014 /* the agent supports this key */ 1015 if (id->agent_fd != -1) 1016 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1017 data, datalen, alg, compat); 1018 1019 /* 1020 * we have already loaded the private key or 1021 * the private key is stored in external hardware 1022 */ 1023 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 1024 return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg, 1025 compat)); 1026 /* load the private key from the file */ 1027 if ((prv = load_identity_file(id)) == NULL) 1028 return SSH_ERR_KEY_NOT_FOUND; 1029 ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1030 sshkey_free(prv); 1031 return (ret); 1032 } 1033 1034 static int 1035 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1036 { 1037 Buffer b; 1038 Identity *private_id; 1039 u_char *blob, *signature; 1040 size_t slen; 1041 u_int bloblen, skip = 0; 1042 int matched, ret = -1, have_sig = 1; 1043 char *fp; 1044 1045 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1046 SSH_FP_DEFAULT)) == NULL) 1047 return 0; 1048 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1049 free(fp); 1050 1051 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1052 /* we cannot handle this key */ 1053 debug3("sign_and_send_pubkey: cannot handle key"); 1054 return 0; 1055 } 1056 /* data to be signed */ 1057 buffer_init(&b); 1058 if (datafellows & SSH_OLD_SESSIONID) { 1059 buffer_append(&b, session_id2, session_id2_len); 1060 skip = session_id2_len; 1061 } else { 1062 buffer_put_string(&b, session_id2, session_id2_len); 1063 skip = buffer_len(&b); 1064 } 1065 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1066 buffer_put_cstring(&b, authctxt->server_user); 1067 buffer_put_cstring(&b, 1068 datafellows & SSH_BUG_PKSERVICE ? 1069 "ssh-userauth" : 1070 authctxt->service); 1071 if (datafellows & SSH_BUG_PKAUTH) { 1072 buffer_put_char(&b, have_sig); 1073 } else { 1074 buffer_put_cstring(&b, authctxt->method->name); 1075 buffer_put_char(&b, have_sig); 1076 buffer_put_cstring(&b, identity_sign_encode(id)); 1077 } 1078 buffer_put_string(&b, blob, bloblen); 1079 1080 /* 1081 * If the key is an certificate, try to find a matching private key 1082 * and use it to complete the signature. 1083 * If no such private key exists, fall back to trying the certificate 1084 * key itself in case it has a private half already loaded. 1085 */ 1086 if (key_is_cert(id->key)) { 1087 matched = 0; 1088 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1089 if (sshkey_equal_public(id->key, private_id->key) && 1090 id->key->type != private_id->key->type) { 1091 id = private_id; 1092 matched = 1; 1093 break; 1094 } 1095 } 1096 if (matched) { 1097 debug2("%s: using private key \"%s\"%s for " 1098 "certificate", __func__, id->filename, 1099 id->agent_fd != -1 ? " from agent" : ""); 1100 } else { 1101 debug("%s: no separate private key for certificate " 1102 "\"%s\"", __func__, id->filename); 1103 } 1104 } 1105 1106 /* generate signature */ 1107 ret = identity_sign(id, &signature, &slen, 1108 buffer_ptr(&b), buffer_len(&b), datafellows); 1109 if (ret != 0) { 1110 if (ret != SSH_ERR_KEY_NOT_FOUND) 1111 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1112 free(blob); 1113 buffer_free(&b); 1114 return 0; 1115 } 1116 #ifdef DEBUG_PK 1117 buffer_dump(&b); 1118 #endif 1119 if (datafellows & SSH_BUG_PKSERVICE) { 1120 buffer_clear(&b); 1121 buffer_append(&b, session_id2, session_id2_len); 1122 skip = session_id2_len; 1123 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1124 buffer_put_cstring(&b, authctxt->server_user); 1125 buffer_put_cstring(&b, authctxt->service); 1126 buffer_put_cstring(&b, authctxt->method->name); 1127 buffer_put_char(&b, have_sig); 1128 if (!(datafellows & SSH_BUG_PKAUTH)) 1129 buffer_put_cstring(&b, key_ssh_name(id->key)); 1130 buffer_put_string(&b, blob, bloblen); 1131 } 1132 free(blob); 1133 1134 /* append signature */ 1135 buffer_put_string(&b, signature, slen); 1136 free(signature); 1137 1138 /* skip session id and packet type */ 1139 if (buffer_len(&b) < skip + 1) 1140 fatal("userauth_pubkey: internal error"); 1141 buffer_consume(&b, skip + 1); 1142 1143 /* put remaining data from buffer into packet */ 1144 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1145 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1146 buffer_free(&b); 1147 packet_send(); 1148 1149 return 1; 1150 } 1151 1152 static int 1153 send_pubkey_test(Authctxt *authctxt, Identity *id) 1154 { 1155 u_char *blob; 1156 u_int bloblen, have_sig = 0; 1157 1158 debug3("send_pubkey_test"); 1159 1160 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1161 /* we cannot handle this key */ 1162 debug3("send_pubkey_test: cannot handle key"); 1163 return 0; 1164 } 1165 /* register callback for USERAUTH_PK_OK message */ 1166 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1167 1168 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1169 packet_put_cstring(authctxt->server_user); 1170 packet_put_cstring(authctxt->service); 1171 packet_put_cstring(authctxt->method->name); 1172 packet_put_char(have_sig); 1173 if (!(datafellows & SSH_BUG_PKAUTH)) 1174 packet_put_cstring(identity_sign_encode(id)); 1175 packet_put_string(blob, bloblen); 1176 free(blob); 1177 packet_send(); 1178 return 1; 1179 } 1180 1181 static Key * 1182 load_identity_file(Identity *id) 1183 { 1184 Key *private = NULL; 1185 char prompt[300], *passphrase, *comment; 1186 int r, perm_ok = 0, quit = 0, i; 1187 struct stat st; 1188 1189 if (stat(id->filename, &st) < 0) { 1190 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1191 id->filename, strerror(errno)); 1192 return NULL; 1193 } 1194 snprintf(prompt, sizeof prompt, 1195 "Enter passphrase for key '%.100s': ", id->filename); 1196 for (i = 0; i <= options.number_of_password_prompts; i++) { 1197 if (i == 0) 1198 passphrase = ""; 1199 else { 1200 passphrase = read_passphrase(prompt, 0); 1201 if (*passphrase == '\0') { 1202 debug2("no passphrase given, try next key"); 1203 free(passphrase); 1204 break; 1205 } 1206 } 1207 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1208 passphrase, &private, &comment, &perm_ok))) { 1209 case 0: 1210 break; 1211 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1212 if (options.batch_mode) { 1213 quit = 1; 1214 break; 1215 } 1216 if (i != 0) 1217 debug2("bad passphrase given, try again..."); 1218 break; 1219 case SSH_ERR_SYSTEM_ERROR: 1220 if (errno == ENOENT) { 1221 debug2("Load key \"%s\": %s", 1222 id->filename, ssh_err(r)); 1223 quit = 1; 1224 break; 1225 } 1226 /* FALLTHROUGH */ 1227 default: 1228 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1229 quit = 1; 1230 break; 1231 } 1232 if (!quit && private != NULL && id->agent_fd == -1 && 1233 !(id->key && id->isprivate)) 1234 maybe_add_key_to_agent(id->filename, private, comment, 1235 passphrase); 1236 if (i > 0) { 1237 explicit_bzero(passphrase, strlen(passphrase)); 1238 free(passphrase); 1239 } 1240 free(comment); 1241 if (private != NULL || quit) 1242 break; 1243 } 1244 return private; 1245 } 1246 1247 /* 1248 * try keys in the following order: 1249 * 1. certificates listed in the config file 1250 * 2. other input certificates 1251 * 3. agent keys that are found in the config file 1252 * 4. other agent keys 1253 * 5. keys that are only listed in the config file 1254 */ 1255 static void 1256 pubkey_prepare(Authctxt *authctxt) 1257 { 1258 struct identity *id, *id2, *tmp; 1259 struct idlist agent, files, *preferred; 1260 struct sshkey *key; 1261 int agent_fd = -1, i, r, found; 1262 size_t j; 1263 struct ssh_identitylist *idlist; 1264 1265 TAILQ_INIT(&agent); /* keys from the agent */ 1266 TAILQ_INIT(&files); /* keys from the config file */ 1267 preferred = &authctxt->keys; 1268 TAILQ_INIT(preferred); /* preferred order of keys */ 1269 1270 /* list of keys stored in the filesystem and PKCS#11 */ 1271 for (i = 0; i < options.num_identity_files; i++) { 1272 key = options.identity_keys[i]; 1273 if (key && key->type == KEY_RSA1) 1274 continue; 1275 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1276 continue; 1277 options.identity_keys[i] = NULL; 1278 id = xcalloc(1, sizeof(*id)); 1279 id->agent_fd = -1; 1280 id->key = key; 1281 id->filename = xstrdup(options.identity_files[i]); 1282 id->userprovided = options.identity_file_userprovided[i]; 1283 TAILQ_INSERT_TAIL(&files, id, next); 1284 } 1285 /* list of certificates specified by user */ 1286 for (i = 0; i < options.num_certificate_files; i++) { 1287 key = options.certificates[i]; 1288 if (!key_is_cert(key) || key->cert == NULL || 1289 key->cert->type != SSH2_CERT_TYPE_USER) 1290 continue; 1291 id = xcalloc(1, sizeof(*id)); 1292 id->agent_fd = -1; 1293 id->key = key; 1294 id->filename = xstrdup(options.certificate_files[i]); 1295 id->userprovided = options.certificate_file_userprovided[i]; 1296 TAILQ_INSERT_TAIL(preferred, id, next); 1297 } 1298 /* list of keys supported by the agent */ 1299 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1300 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1301 debug("%s: ssh_get_authentication_socket: %s", 1302 __func__, ssh_err(r)); 1303 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1304 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1305 debug("%s: ssh_fetch_identitylist: %s", 1306 __func__, ssh_err(r)); 1307 close(agent_fd); 1308 } else { 1309 for (j = 0; j < idlist->nkeys; j++) { 1310 found = 0; 1311 TAILQ_FOREACH(id, &files, next) { 1312 /* 1313 * agent keys from the config file are 1314 * preferred 1315 */ 1316 if (sshkey_equal(idlist->keys[j], id->key)) { 1317 TAILQ_REMOVE(&files, id, next); 1318 TAILQ_INSERT_TAIL(preferred, id, next); 1319 id->agent_fd = agent_fd; 1320 found = 1; 1321 break; 1322 } 1323 } 1324 if (!found && !options.identities_only) { 1325 id = xcalloc(1, sizeof(*id)); 1326 /* XXX "steals" key/comment from idlist */ 1327 id->key = idlist->keys[j]; 1328 id->filename = idlist->comments[j]; 1329 idlist->keys[j] = NULL; 1330 idlist->comments[j] = NULL; 1331 id->agent_fd = agent_fd; 1332 TAILQ_INSERT_TAIL(&agent, id, next); 1333 } 1334 } 1335 ssh_free_identitylist(idlist); 1336 /* append remaining agent keys */ 1337 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1338 TAILQ_REMOVE(&agent, id, next); 1339 TAILQ_INSERT_TAIL(preferred, id, next); 1340 } 1341 authctxt->agent_fd = agent_fd; 1342 } 1343 /* Prefer PKCS11 keys that are explicitly listed */ 1344 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1345 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1346 continue; 1347 found = 0; 1348 TAILQ_FOREACH(id2, &files, next) { 1349 if (id2->key == NULL || 1350 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1351 continue; 1352 if (sshkey_equal(id->key, id2->key)) { 1353 TAILQ_REMOVE(&files, id, next); 1354 TAILQ_INSERT_TAIL(preferred, id, next); 1355 found = 1; 1356 break; 1357 } 1358 } 1359 /* If IdentitiesOnly set and key not found then don't use it */ 1360 if (!found && options.identities_only) { 1361 TAILQ_REMOVE(&files, id, next); 1362 explicit_bzero(id, sizeof(*id)); 1363 free(id); 1364 } 1365 } 1366 /* append remaining keys from the config file */ 1367 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1368 TAILQ_REMOVE(&files, id, next); 1369 TAILQ_INSERT_TAIL(preferred, id, next); 1370 } 1371 /* finally, filter by PubkeyAcceptedKeyTypes */ 1372 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1373 if (id->key != NULL && 1374 match_pattern_list(sshkey_ssh_name(id->key), 1375 options.pubkey_key_types, 0) != 1) { 1376 debug("Skipping %s key %s - " 1377 "not in PubkeyAcceptedKeyTypes", 1378 sshkey_ssh_name(id->key), id->filename); 1379 TAILQ_REMOVE(preferred, id, next); 1380 sshkey_free(id->key); 1381 free(id->filename); 1382 memset(id, 0, sizeof(*id)); 1383 continue; 1384 } 1385 debug2("key: %s (%p)%s%s", id->filename, id->key, 1386 id->userprovided ? ", explicit" : "", 1387 id->agent_fd != -1 ? ", agent" : ""); 1388 } 1389 } 1390 1391 static void 1392 pubkey_cleanup(Authctxt *authctxt) 1393 { 1394 Identity *id; 1395 1396 if (authctxt->agent_fd != -1) 1397 ssh_close_authentication_socket(authctxt->agent_fd); 1398 for (id = TAILQ_FIRST(&authctxt->keys); id; 1399 id = TAILQ_FIRST(&authctxt->keys)) { 1400 TAILQ_REMOVE(&authctxt->keys, id, next); 1401 sshkey_free(id->key); 1402 free(id->filename); 1403 free(id); 1404 } 1405 } 1406 1407 static int 1408 try_identity(Identity *id) 1409 { 1410 if (!id->key) 1411 return (0); 1412 if (key_type_plain(id->key->type) == KEY_RSA && 1413 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1414 debug("Skipped %s key %s for RSA/MD5 server", 1415 key_type(id->key), id->filename); 1416 return (0); 1417 } 1418 return (id->key->type != KEY_RSA1); 1419 } 1420 1421 int 1422 userauth_pubkey(Authctxt *authctxt) 1423 { 1424 Identity *id; 1425 int sent = 0; 1426 1427 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1428 if (id->tried++) 1429 return (0); 1430 /* move key to the end of the queue */ 1431 TAILQ_REMOVE(&authctxt->keys, id, next); 1432 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1433 /* 1434 * send a test message if we have the public key. for 1435 * encrypted keys we cannot do this and have to load the 1436 * private key instead 1437 */ 1438 if (id->key != NULL) { 1439 if (try_identity(id)) { 1440 debug("Offering %s public key: %s", 1441 key_type(id->key), id->filename); 1442 sent = send_pubkey_test(authctxt, id); 1443 } 1444 } else { 1445 debug("Trying private key: %s", id->filename); 1446 id->key = load_identity_file(id); 1447 if (id->key != NULL) { 1448 if (try_identity(id)) { 1449 id->isprivate = 1; 1450 sent = sign_and_send_pubkey( 1451 authctxt, id); 1452 } 1453 key_free(id->key); 1454 id->key = NULL; 1455 } 1456 } 1457 if (sent) 1458 return (sent); 1459 } 1460 return (0); 1461 } 1462 1463 /* 1464 * Send userauth request message specifying keyboard-interactive method. 1465 */ 1466 int 1467 userauth_kbdint(Authctxt *authctxt) 1468 { 1469 static int attempt = 0; 1470 1471 if (attempt++ >= options.number_of_password_prompts) 1472 return 0; 1473 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1474 if (attempt > 1 && !authctxt->info_req_seen) { 1475 debug3("userauth_kbdint: disable: no info_req_seen"); 1476 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1477 return 0; 1478 } 1479 1480 debug2("userauth_kbdint"); 1481 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1482 packet_put_cstring(authctxt->server_user); 1483 packet_put_cstring(authctxt->service); 1484 packet_put_cstring(authctxt->method->name); 1485 packet_put_cstring(""); /* lang */ 1486 packet_put_cstring(options.kbd_interactive_devices ? 1487 options.kbd_interactive_devices : ""); 1488 packet_send(); 1489 1490 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1491 return 1; 1492 } 1493 1494 /* 1495 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1496 */ 1497 int 1498 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1499 { 1500 Authctxt *authctxt = ctxt; 1501 char *name, *inst, *lang, *prompt, *response; 1502 u_int num_prompts, i; 1503 int echo = 0; 1504 1505 debug2("input_userauth_info_req"); 1506 1507 if (authctxt == NULL) 1508 fatal("input_userauth_info_req: no authentication context"); 1509 1510 authctxt->info_req_seen = 1; 1511 1512 name = packet_get_string(NULL); 1513 inst = packet_get_string(NULL); 1514 lang = packet_get_string(NULL); 1515 if (strlen(name) > 0) 1516 logit("%s", name); 1517 if (strlen(inst) > 0) 1518 logit("%s", inst); 1519 free(name); 1520 free(inst); 1521 free(lang); 1522 1523 num_prompts = packet_get_int(); 1524 /* 1525 * Begin to build info response packet based on prompts requested. 1526 * We commit to providing the correct number of responses, so if 1527 * further on we run into a problem that prevents this, we have to 1528 * be sure and clean this up and send a correct error response. 1529 */ 1530 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1531 packet_put_int(num_prompts); 1532 1533 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1534 for (i = 0; i < num_prompts; i++) { 1535 prompt = packet_get_string(NULL); 1536 echo = packet_get_char(); 1537 1538 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1539 1540 packet_put_cstring(response); 1541 explicit_bzero(response, strlen(response)); 1542 free(response); 1543 free(prompt); 1544 } 1545 packet_check_eom(); /* done with parsing incoming message. */ 1546 1547 packet_add_padding(64); 1548 packet_send(); 1549 return 0; 1550 } 1551 1552 static int 1553 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1554 const u_char *data, size_t datalen) 1555 { 1556 struct sshbuf *b; 1557 struct stat st; 1558 pid_t pid; 1559 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1560 u_char rversion = 0, version = 2; 1561 void (*osigchld)(int); 1562 1563 *sigp = NULL; 1564 *lenp = 0; 1565 1566 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1567 error("%s: not installed: %s", __func__, strerror(errno)); 1568 return -1; 1569 } 1570 if (fflush(stdout) != 0) { 1571 error("%s: fflush: %s", __func__, strerror(errno)); 1572 return -1; 1573 } 1574 if (pipe(to) < 0) { 1575 error("%s: pipe: %s", __func__, strerror(errno)); 1576 return -1; 1577 } 1578 if (pipe(from) < 0) { 1579 error("%s: pipe: %s", __func__, strerror(errno)); 1580 return -1; 1581 } 1582 if ((pid = fork()) < 0) { 1583 error("%s: fork: %s", __func__, strerror(errno)); 1584 return -1; 1585 } 1586 osigchld = signal(SIGCHLD, SIG_DFL); 1587 if (pid == 0) { 1588 /* keep the socket on exec */ 1589 fcntl(sock, F_SETFD, 0); 1590 permanently_drop_suid(getuid()); 1591 close(from[0]); 1592 if (dup2(from[1], STDOUT_FILENO) < 0) 1593 fatal("%s: dup2: %s", __func__, strerror(errno)); 1594 close(to[1]); 1595 if (dup2(to[0], STDIN_FILENO) < 0) 1596 fatal("%s: dup2: %s", __func__, strerror(errno)); 1597 close(from[1]); 1598 close(to[0]); 1599 /* Close everything but stdio and the socket */ 1600 for (i = STDERR_FILENO + 1; i < sock; i++) 1601 close(i); 1602 closefrom(sock + 1); 1603 debug3("%s: [child] pid=%ld, exec %s", 1604 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1605 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1606 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1607 strerror(errno)); 1608 } 1609 close(from[1]); 1610 close(to[0]); 1611 1612 if ((b = sshbuf_new()) == NULL) 1613 fatal("%s: sshbuf_new failed", __func__); 1614 /* send # of sock, data to be signed */ 1615 if ((r = sshbuf_put_u32(b, sock) != 0) || 1616 (r = sshbuf_put_string(b, data, datalen)) != 0) 1617 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1618 if (ssh_msg_send(to[1], version, b) == -1) 1619 fatal("%s: couldn't send request", __func__); 1620 sshbuf_reset(b); 1621 r = ssh_msg_recv(from[0], b); 1622 close(from[0]); 1623 close(to[1]); 1624 if (r < 0) { 1625 error("%s: no reply", __func__); 1626 goto fail; 1627 } 1628 1629 errno = 0; 1630 while (waitpid(pid, &status, 0) < 0) { 1631 if (errno != EINTR) { 1632 error("%s: waitpid %ld: %s", 1633 __func__, (long)pid, strerror(errno)); 1634 goto fail; 1635 } 1636 } 1637 if (!WIFEXITED(status)) { 1638 error("%s: exited abnormally", __func__); 1639 goto fail; 1640 } 1641 if (WEXITSTATUS(status) != 0) { 1642 error("%s: exited with status %d", 1643 __func__, WEXITSTATUS(status)); 1644 goto fail; 1645 } 1646 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1647 error("%s: buffer error: %s", __func__, ssh_err(r)); 1648 goto fail; 1649 } 1650 if (rversion != version) { 1651 error("%s: bad version", __func__); 1652 goto fail; 1653 } 1654 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1655 error("%s: buffer error: %s", __func__, ssh_err(r)); 1656 fail: 1657 signal(SIGCHLD, osigchld); 1658 sshbuf_free(b); 1659 return -1; 1660 } 1661 signal(SIGCHLD, osigchld); 1662 sshbuf_free(b); 1663 1664 return 0; 1665 } 1666 1667 int 1668 userauth_hostbased(Authctxt *authctxt) 1669 { 1670 struct ssh *ssh = active_state; 1671 struct sshkey *private = NULL; 1672 struct sshbuf *b = NULL; 1673 const char *service; 1674 u_char *sig = NULL, *keyblob = NULL; 1675 char *fp = NULL, *chost = NULL, *lname = NULL; 1676 size_t siglen = 0, keylen = 0; 1677 int i, r, success = 0; 1678 1679 if (authctxt->ktypes == NULL) { 1680 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1681 authctxt->ktypes = authctxt->oktypes; 1682 } 1683 1684 /* 1685 * Work through each listed type pattern in HostbasedKeyTypes, 1686 * trying each hostkey that matches the type in turn. 1687 */ 1688 for (;;) { 1689 if (authctxt->active_ktype == NULL) 1690 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1691 if (authctxt->active_ktype == NULL || 1692 *authctxt->active_ktype == '\0') 1693 break; 1694 debug3("%s: trying key type %s", __func__, 1695 authctxt->active_ktype); 1696 1697 /* check for a useful key */ 1698 private = NULL; 1699 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1700 if (authctxt->sensitive->keys[i] == NULL || 1701 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1702 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1703 continue; 1704 if (match_pattern_list( 1705 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1706 authctxt->active_ktype, 0) != 1) 1707 continue; 1708 /* we take and free the key */ 1709 private = authctxt->sensitive->keys[i]; 1710 authctxt->sensitive->keys[i] = NULL; 1711 break; 1712 } 1713 /* Found one */ 1714 if (private != NULL) 1715 break; 1716 /* No more keys of this type; advance */ 1717 authctxt->active_ktype = NULL; 1718 } 1719 if (private == NULL) { 1720 free(authctxt->oktypes); 1721 authctxt->oktypes = authctxt->ktypes = NULL; 1722 authctxt->active_ktype = NULL; 1723 debug("No more client hostkeys for hostbased authentication."); 1724 goto out; 1725 } 1726 1727 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1728 SSH_FP_DEFAULT)) == NULL) { 1729 error("%s: sshkey_fingerprint failed", __func__); 1730 goto out; 1731 } 1732 debug("%s: trying hostkey %s %s", 1733 __func__, sshkey_ssh_name(private), fp); 1734 1735 /* figure out a name for the client host */ 1736 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1737 error("%s: cannot get local ipaddr/name", __func__); 1738 goto out; 1739 } 1740 1741 /* XXX sshbuf_put_stringf? */ 1742 xasprintf(&chost, "%s.", lname); 1743 debug2("%s: chost %s", __func__, chost); 1744 1745 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1746 authctxt->service; 1747 1748 /* construct data */ 1749 if ((b = sshbuf_new()) == NULL) { 1750 error("%s: sshbuf_new failed", __func__); 1751 goto out; 1752 } 1753 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1754 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1755 goto out; 1756 } 1757 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1758 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1759 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1760 (r = sshbuf_put_cstring(b, service)) != 0 || 1761 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1762 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1763 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1764 (r = sshbuf_put_cstring(b, chost)) != 0 || 1765 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1766 error("%s: buffer error: %s", __func__, ssh_err(r)); 1767 goto out; 1768 } 1769 1770 #ifdef DEBUG_PK 1771 sshbuf_dump(b, stderr); 1772 #endif 1773 if (authctxt->sensitive->external_keysign) 1774 r = ssh_keysign(private, &sig, &siglen, 1775 sshbuf_ptr(b), sshbuf_len(b)); 1776 else if ((r = sshkey_sign(private, &sig, &siglen, 1777 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1778 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1779 if (r != 0) { 1780 error("sign using hostkey %s %s failed", 1781 sshkey_ssh_name(private), fp); 1782 goto out; 1783 } 1784 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1785 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1786 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1787 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1788 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1789 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1790 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1791 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1792 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1793 (r = sshpkt_send(ssh)) != 0) { 1794 error("%s: packet error: %s", __func__, ssh_err(r)); 1795 goto out; 1796 } 1797 success = 1; 1798 1799 out: 1800 if (sig != NULL) { 1801 explicit_bzero(sig, siglen); 1802 free(sig); 1803 } 1804 free(keyblob); 1805 free(lname); 1806 free(fp); 1807 free(chost); 1808 sshkey_free(private); 1809 sshbuf_free(b); 1810 1811 return success; 1812 } 1813 1814 /* find auth method */ 1815 1816 /* 1817 * given auth method name, if configurable options permit this method fill 1818 * in auth_ident field and return true, otherwise return false. 1819 */ 1820 static int 1821 authmethod_is_enabled(Authmethod *method) 1822 { 1823 if (method == NULL) 1824 return 0; 1825 /* return false if options indicate this method is disabled */ 1826 if (method->enabled == NULL || *method->enabled == 0) 1827 return 0; 1828 /* return false if batch mode is enabled but method needs interactive mode */ 1829 if (method->batch_flag != NULL && *method->batch_flag != 0) 1830 return 0; 1831 return 1; 1832 } 1833 1834 static Authmethod * 1835 authmethod_lookup(const char *name) 1836 { 1837 Authmethod *method = NULL; 1838 if (name != NULL) 1839 for (method = authmethods; method->name != NULL; method++) 1840 if (strcmp(name, method->name) == 0) 1841 return method; 1842 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1843 return NULL; 1844 } 1845 1846 /* XXX internal state */ 1847 static Authmethod *current = NULL; 1848 static char *supported = NULL; 1849 static char *preferred = NULL; 1850 1851 /* 1852 * Given the authentication method list sent by the server, return the 1853 * next method we should try. If the server initially sends a nil list, 1854 * use a built-in default list. 1855 */ 1856 static Authmethod * 1857 authmethod_get(char *authlist) 1858 { 1859 char *name = NULL; 1860 u_int next; 1861 1862 /* Use a suitable default if we're passed a nil list. */ 1863 if (authlist == NULL || strlen(authlist) == 0) 1864 authlist = options.preferred_authentications; 1865 1866 if (supported == NULL || strcmp(authlist, supported) != 0) { 1867 debug3("start over, passed a different list %s", authlist); 1868 free(supported); 1869 supported = xstrdup(authlist); 1870 preferred = options.preferred_authentications; 1871 debug3("preferred %s", preferred); 1872 current = NULL; 1873 } else if (current != NULL && authmethod_is_enabled(current)) 1874 return current; 1875 1876 for (;;) { 1877 if ((name = match_list(preferred, supported, &next)) == NULL) { 1878 debug("No more authentication methods to try."); 1879 current = NULL; 1880 return NULL; 1881 } 1882 preferred += next; 1883 debug3("authmethod_lookup %s", name); 1884 debug3("remaining preferred: %s", preferred); 1885 if ((current = authmethod_lookup(name)) != NULL && 1886 authmethod_is_enabled(current)) { 1887 debug3("authmethod_is_enabled %s", name); 1888 debug("Next authentication method: %s", name); 1889 free(name); 1890 return current; 1891 } 1892 free(name); 1893 } 1894 } 1895 1896 static char * 1897 authmethods_get(void) 1898 { 1899 Authmethod *method = NULL; 1900 Buffer b; 1901 char *list; 1902 1903 buffer_init(&b); 1904 for (method = authmethods; method->name != NULL; method++) { 1905 if (authmethod_is_enabled(method)) { 1906 if (buffer_len(&b) > 0) 1907 buffer_append(&b, ",", 1); 1908 buffer_append(&b, method->name, strlen(method->name)); 1909 } 1910 } 1911 if ((list = sshbuf_dup_string(&b)) == NULL) 1912 fatal("%s: sshbuf_dup_string failed", __func__); 1913 buffer_free(&b); 1914 return list; 1915 } 1916 1917
Indexes created Fri Mar 06 19:51:54 UTC 2026