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 "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <netdb.h> 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdarg.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <unistd.h> 43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 44 #include <vis.h> 45 #endif 46 47 #include "openbsd-compat/sys-queue.h" 48 49 #include "xmalloc.h" 50 #include "ssh.h" 51 #include "ssh2.h" 52 #include "buffer.h" 53 #include "packet.h" 54 #include "compat.h" 55 #include "cipher.h" 56 #include "key.h" 57 #include "kex.h" 58 #include "myproposal.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 76 #ifdef GSSAPI 77 #include "ssh-gss.h" 78 #endif 79 80 /* import */ 81 extern char *client_version_string; 82 extern char *server_version_string; 83 extern Options options; 84 85 /* 86 * SSH2 key exchange 87 */ 88 89 u_char *session_id2 = NULL; 90 u_int session_id2_len = 0; 91 92 char *xxx_host; 93 struct sockaddr *xxx_hostaddr; 94 95 static int 96 verify_host_key_callback(Key *hostkey, struct ssh *ssh) 97 { 98 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 99 fatal("Host key verification failed."); 100 return 0; 101 } 102 103 static char * 104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 105 { 106 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 107 size_t maxlen; 108 struct hostkeys *hostkeys; 109 int ktype; 110 u_int i; 111 112 /* Find all hostkeys for this hostname */ 113 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 114 hostkeys = init_hostkeys(); 115 for (i = 0; i < options.num_user_hostfiles; i++) 116 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 117 for (i = 0; i < options.num_system_hostfiles; i++) 118 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 119 120 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 121 maxlen = strlen(avail) + 1; 122 first = xmalloc(maxlen); 123 last = xmalloc(maxlen); 124 *first = *last = '\0'; 125 126 #define ALG_APPEND(to, from) \ 127 do { \ 128 if (*to != '\0') \ 129 strlcat(to, ",", maxlen); \ 130 strlcat(to, from, maxlen); \ 131 } while (0) 132 133 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 134 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 135 fatal("%s: unknown alg %s", __func__, alg); 136 if (lookup_key_in_hostkeys_by_type(hostkeys, 137 sshkey_type_plain(ktype), NULL)) 138 ALG_APPEND(first, alg); 139 else 140 ALG_APPEND(last, alg); 141 } 142 #undef ALG_APPEND 143 xasprintf(&ret, "%s%s%s", first, 144 (*first == '\0' || *last == '\0') ? "" : ",", last); 145 if (*first != '\0') 146 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 147 148 free(first); 149 free(last); 150 free(hostname); 151 free(oavail); 152 free_hostkeys(hostkeys); 153 154 return ret; 155 } 156 157 void 158 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 159 { 160 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 161 char *s; 162 struct kex *kex; 163 int r; 164 165 xxx_host = host; 166 xxx_hostaddr = hostaddr; 167 168 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 169 fatal("%s: kex_names_cat", __func__); 170 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 171 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 172 compat_cipher_proposal(options.ciphers); 173 myproposal[PROPOSAL_ENC_ALGS_STOC] = 174 compat_cipher_proposal(options.ciphers); 175 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 176 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 177 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 178 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 179 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 180 if (options.hostkeyalgorithms != NULL) { 181 if (kex_assemble_names(KEX_DEFAULT_PK_ALG, 182 &options.hostkeyalgorithms) != 0) 183 fatal("%s: kex_assemble_namelist", __func__); 184 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 185 compat_pkalg_proposal(options.hostkeyalgorithms); 186 } else { 187 /* Enforce default */ 188 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 189 /* Prefer algorithms that we already have keys for */ 190 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 191 compat_pkalg_proposal( 192 order_hostkeyalgs(host, hostaddr, port)); 193 } 194 195 if (options.rekey_limit || options.rekey_interval) 196 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 197 (time_t)options.rekey_interval); 198 199 /* start key exchange */ 200 if ((r = kex_setup(active_state, myproposal)) != 0) 201 fatal("kex_setup: %s", ssh_err(r)); 202 kex = active_state->kex; 203 #ifdef WITH_OPENSSL 204 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 205 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 206 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 207 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 208 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 209 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 210 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 211 # ifdef OPENSSL_HAS_ECC 212 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 213 # endif 214 #endif 215 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 216 kex->client_version_string=client_version_string; 217 kex->server_version_string=server_version_string; 218 kex->verify_host_key=&verify_host_key_callback; 219 220 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 221 222 /* remove ext-info from the KEX proposals for rekeying */ 223 myproposal[PROPOSAL_KEX_ALGS] = 224 compat_kex_proposal(options.kex_algorithms); 225 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 226 fatal("kex_prop2buf: %s", ssh_err(r)); 227 228 session_id2 = kex->session_id; 229 session_id2_len = kex->session_id_len; 230 231 #ifdef DEBUG_KEXDH 232 /* send 1st encrypted/maced/compressed message */ 233 packet_start(SSH2_MSG_IGNORE); 234 packet_put_cstring("markus"); 235 packet_send(); 236 packet_write_wait(); 237 #endif 238 } 239 240 /* 241 * Authenticate user 242 */ 243 244 typedef struct cauthctxt Authctxt; 245 typedef struct cauthmethod Authmethod; 246 typedef struct identity Identity; 247 typedef struct idlist Idlist; 248 249 struct identity { 250 TAILQ_ENTRY(identity) next; 251 int agent_fd; /* >=0 if agent supports key */ 252 struct sshkey *key; /* public/private key */ 253 char *filename; /* comment for agent-only keys */ 254 int tried; 255 int isprivate; /* key points to the private key */ 256 int userprovided; 257 }; 258 TAILQ_HEAD(idlist, identity); 259 260 struct cauthctxt { 261 const char *server_user; 262 const char *local_user; 263 const char *host; 264 const char *service; 265 struct cauthmethod *method; 266 sig_atomic_t success; 267 char *authlist; 268 int attempt; 269 /* pubkey */ 270 struct idlist keys; 271 int agent_fd; 272 /* hostbased */ 273 Sensitive *sensitive; 274 char *oktypes, *ktypes; 275 const char *active_ktype; 276 /* kbd-interactive */ 277 int info_req_seen; 278 /* generic */ 279 void *methoddata; 280 }; 281 282 struct cauthmethod { 283 char *name; /* string to compare against server's list */ 284 int (*userauth)(Authctxt *authctxt); 285 void (*cleanup)(Authctxt *authctxt); 286 int *enabled; /* flag in option struct that enables method */ 287 int *batch_flag; /* flag in option struct that disables method */ 288 }; 289 290 int input_userauth_service_accept(int, u_int32_t, void *); 291 int input_userauth_ext_info(int, u_int32_t, void *); 292 int input_userauth_success(int, u_int32_t, void *); 293 int input_userauth_success_unexpected(int, u_int32_t, void *); 294 int input_userauth_failure(int, u_int32_t, void *); 295 int input_userauth_banner(int, u_int32_t, void *); 296 int input_userauth_error(int, u_int32_t, void *); 297 int input_userauth_info_req(int, u_int32_t, void *); 298 int input_userauth_pk_ok(int, u_int32_t, void *); 299 int input_userauth_passwd_changereq(int, u_int32_t, void *); 300 301 int userauth_none(Authctxt *); 302 int userauth_pubkey(Authctxt *); 303 int userauth_passwd(Authctxt *); 304 int userauth_kbdint(Authctxt *); 305 int userauth_hostbased(Authctxt *); 306 307 #ifdef GSSAPI 308 int userauth_gssapi(Authctxt *authctxt); 309 int input_gssapi_response(int type, u_int32_t, void *); 310 int input_gssapi_token(int type, u_int32_t, void *); 311 int input_gssapi_hash(int type, u_int32_t, void *); 312 int input_gssapi_error(int, u_int32_t, void *); 313 int input_gssapi_errtok(int, u_int32_t, void *); 314 #endif 315 316 void userauth(Authctxt *, char *); 317 318 static int sign_and_send_pubkey(Authctxt *, Identity *); 319 static void pubkey_prepare(Authctxt *); 320 static void pubkey_cleanup(Authctxt *); 321 static Key *load_identity_file(Identity *); 322 323 static Authmethod *authmethod_get(char *authlist); 324 static Authmethod *authmethod_lookup(const char *name); 325 static char *authmethods_get(void); 326 327 Authmethod authmethods[] = { 328 #ifdef GSSAPI 329 {"gssapi-with-mic", 330 userauth_gssapi, 331 NULL, 332 &options.gss_authentication, 333 NULL}, 334 #endif 335 {"hostbased", 336 userauth_hostbased, 337 NULL, 338 &options.hostbased_authentication, 339 NULL}, 340 {"publickey", 341 userauth_pubkey, 342 NULL, 343 &options.pubkey_authentication, 344 NULL}, 345 {"keyboard-interactive", 346 userauth_kbdint, 347 NULL, 348 &options.kbd_interactive_authentication, 349 &options.batch_mode}, 350 {"password", 351 userauth_passwd, 352 NULL, 353 &options.password_authentication, 354 &options.batch_mode}, 355 {"none", 356 userauth_none, 357 NULL, 358 NULL, 359 NULL}, 360 {NULL, NULL, NULL, NULL, NULL} 361 }; 362 363 void 364 ssh_userauth2(const char *local_user, const char *server_user, char *host, 365 Sensitive *sensitive) 366 { 367 struct ssh *ssh = active_state; 368 Authctxt authctxt; 369 int r; 370 371 if (options.challenge_response_authentication) 372 options.kbd_interactive_authentication = 1; 373 if (options.preferred_authentications == NULL) 374 options.preferred_authentications = authmethods_get(); 375 376 /* setup authentication context */ 377 memset(&authctxt, 0, sizeof(authctxt)); 378 pubkey_prepare(&authctxt); 379 authctxt.server_user = server_user; 380 authctxt.local_user = local_user; 381 authctxt.host = host; 382 authctxt.service = "ssh-connection"; /* service name */ 383 authctxt.success = 0; 384 authctxt.method = authmethod_lookup("none"); 385 authctxt.authlist = NULL; 386 authctxt.methoddata = NULL; 387 authctxt.sensitive = sensitive; 388 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 389 authctxt.info_req_seen = 0; 390 authctxt.agent_fd = -1; 391 if (authctxt.method == NULL) 392 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 393 394 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 395 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 396 (r = sshpkt_send(ssh)) != 0) 397 fatal("%s: %s", __func__, ssh_err(r)); 398 399 ssh_dispatch_init(ssh, &input_userauth_error); 400 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 401 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 402 ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 403 404 pubkey_cleanup(&authctxt); 405 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 406 407 debug("Authentication succeeded (%s).", authctxt.method->name); 408 } 409 410 /* ARGSUSED */ 411 int 412 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt) 413 { 414 Authctxt *authctxt = ctxt; 415 struct ssh *ssh = active_state; 416 int r; 417 418 if (ssh_packet_remaining(ssh) > 0) { 419 char *reply; 420 421 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 422 goto out; 423 debug2("service_accept: %s", reply); 424 free(reply); 425 } else { 426 debug2("buggy server: service_accept w/o service"); 427 } 428 if ((r = sshpkt_get_end(ssh)) != 0) 429 goto out; 430 debug("SSH2_MSG_SERVICE_ACCEPT received"); 431 432 /* initial userauth request */ 433 userauth_none(authctxt); 434 435 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 436 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 437 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 438 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 439 r = 0; 440 out: 441 return r; 442 } 443 444 /* ARGSUSED */ 445 int 446 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt) 447 { 448 return kex_input_ext_info(type, seqnr, active_state); 449 } 450 451 void 452 userauth(Authctxt *authctxt, char *authlist) 453 { 454 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 455 authctxt->method->cleanup(authctxt); 456 457 free(authctxt->methoddata); 458 authctxt->methoddata = NULL; 459 if (authlist == NULL) { 460 authlist = authctxt->authlist; 461 } else { 462 free(authctxt->authlist); 463 authctxt->authlist = authlist; 464 } 465 for (;;) { 466 Authmethod *method = authmethod_get(authlist); 467 if (method == NULL) 468 fatal("Permission denied (%s).", authlist); 469 authctxt->method = method; 470 471 /* reset the per method handler */ 472 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 473 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 474 475 /* and try new method */ 476 if (method->userauth(authctxt) != 0) { 477 debug2("we sent a %s packet, wait for reply", method->name); 478 break; 479 } else { 480 debug2("we did not send a packet, disable method"); 481 method->enabled = NULL; 482 } 483 } 484 } 485 486 /* ARGSUSED */ 487 int 488 input_userauth_error(int type, u_int32_t seq, void *ctxt) 489 { 490 fatal("input_userauth_error: bad message during authentication: " 491 "type %d", type); 492 return 0; 493 } 494 495 /* ARGSUSED */ 496 int 497 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 498 { 499 char *msg, *lang; 500 u_int len; 501 502 debug3("%s", __func__); 503 msg = packet_get_string(&len); 504 lang = packet_get_string(NULL); 505 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 506 fmprintf(stderr, "%s", msg); 507 free(msg); 508 free(lang); 509 return 0; 510 } 511 512 /* ARGSUSED */ 513 int 514 input_userauth_success(int type, u_int32_t seq, void *ctxt) 515 { 516 Authctxt *authctxt = ctxt; 517 518 if (authctxt == NULL) 519 fatal("input_userauth_success: no authentication context"); 520 free(authctxt->authlist); 521 authctxt->authlist = NULL; 522 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 523 authctxt->method->cleanup(authctxt); 524 free(authctxt->methoddata); 525 authctxt->methoddata = NULL; 526 authctxt->success = 1; /* break out */ 527 return 0; 528 } 529 530 int 531 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 532 { 533 Authctxt *authctxt = ctxt; 534 535 if (authctxt == NULL) 536 fatal("%s: no authentication context", __func__); 537 538 fatal("Unexpected authentication success during %s.", 539 authctxt->method->name); 540 return 0; 541 } 542 543 /* ARGSUSED */ 544 int 545 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 546 { 547 Authctxt *authctxt = ctxt; 548 char *authlist = NULL; 549 int partial; 550 551 if (authctxt == NULL) 552 fatal("input_userauth_failure: no authentication context"); 553 554 authlist = packet_get_string(NULL); 555 partial = packet_get_char(); 556 packet_check_eom(); 557 558 if (partial != 0) { 559 verbose("Authenticated with partial success."); 560 /* reset state */ 561 pubkey_cleanup(authctxt); 562 pubkey_prepare(authctxt); 563 } 564 debug("Authentications that can continue: %s", authlist); 565 566 userauth(authctxt, authlist); 567 return 0; 568 } 569 570 /* ARGSUSED */ 571 int 572 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 573 { 574 Authctxt *authctxt = ctxt; 575 Key *key = NULL; 576 Identity *id = NULL; 577 Buffer b; 578 int pktype, sent = 0; 579 u_int alen, blen; 580 char *pkalg, *fp; 581 u_char *pkblob; 582 583 if (authctxt == NULL) 584 fatal("input_userauth_pk_ok: no authentication context"); 585 if (datafellows & SSH_BUG_PKOK) { 586 /* this is similar to SSH_BUG_PKAUTH */ 587 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 588 pkblob = packet_get_string(&blen); 589 buffer_init(&b); 590 buffer_append(&b, pkblob, blen); 591 pkalg = buffer_get_string(&b, &alen); 592 buffer_free(&b); 593 } else { 594 pkalg = packet_get_string(&alen); 595 pkblob = packet_get_string(&blen); 596 } 597 packet_check_eom(); 598 599 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 600 601 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 602 debug("unknown pkalg %s", pkalg); 603 goto done; 604 } 605 if ((key = key_from_blob(pkblob, blen)) == NULL) { 606 debug("no key from blob. pkalg %s", pkalg); 607 goto done; 608 } 609 if (key->type != pktype) { 610 error("input_userauth_pk_ok: type mismatch " 611 "for decoded key (received %d, expected %d)", 612 key->type, pktype); 613 goto done; 614 } 615 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 616 SSH_FP_DEFAULT)) == NULL) 617 goto done; 618 debug2("input_userauth_pk_ok: fp %s", fp); 619 free(fp); 620 621 /* 622 * search keys in the reverse order, because last candidate has been 623 * moved to the end of the queue. this also avoids confusion by 624 * duplicate keys 625 */ 626 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 627 if (key_equal(key, id->key)) { 628 sent = sign_and_send_pubkey(authctxt, id); 629 break; 630 } 631 } 632 done: 633 if (key != NULL) 634 key_free(key); 635 free(pkalg); 636 free(pkblob); 637 638 /* try another method if we did not send a packet */ 639 if (sent == 0) 640 userauth(authctxt, NULL); 641 return 0; 642 } 643 644 #ifdef GSSAPI 645 int 646 userauth_gssapi(Authctxt *authctxt) 647 { 648 Gssctxt *gssctxt = NULL; 649 static gss_OID_set gss_supported = NULL; 650 static u_int mech = 0; 651 OM_uint32 min; 652 int ok = 0; 653 654 /* Try one GSSAPI method at a time, rather than sending them all at 655 * once. */ 656 657 if (gss_supported == NULL) 658 gss_indicate_mechs(&min, &gss_supported); 659 660 /* Check to see if the mechanism is usable before we offer it */ 661 while (mech < gss_supported->count && !ok) { 662 /* My DER encoding requires length<128 */ 663 if (gss_supported->elements[mech].length < 128 && 664 ssh_gssapi_check_mechanism(&gssctxt, 665 &gss_supported->elements[mech], authctxt->host)) { 666 ok = 1; /* Mechanism works */ 667 } else { 668 mech++; 669 } 670 } 671 672 if (!ok) 673 return 0; 674 675 authctxt->methoddata=(void *)gssctxt; 676 677 packet_start(SSH2_MSG_USERAUTH_REQUEST); 678 packet_put_cstring(authctxt->server_user); 679 packet_put_cstring(authctxt->service); 680 packet_put_cstring(authctxt->method->name); 681 682 packet_put_int(1); 683 684 packet_put_int((gss_supported->elements[mech].length) + 2); 685 packet_put_char(SSH_GSS_OIDTYPE); 686 packet_put_char(gss_supported->elements[mech].length); 687 packet_put_raw(gss_supported->elements[mech].elements, 688 gss_supported->elements[mech].length); 689 690 packet_send(); 691 692 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 693 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 694 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 695 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 696 697 mech++; /* Move along to next candidate */ 698 699 return 1; 700 } 701 702 static OM_uint32 703 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 704 { 705 Authctxt *authctxt = ctxt; 706 Gssctxt *gssctxt = authctxt->methoddata; 707 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 708 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 709 gss_buffer_desc gssbuf; 710 OM_uint32 status, ms, flags; 711 Buffer b; 712 713 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 714 recv_tok, &send_tok, &flags); 715 716 if (send_tok.length > 0) { 717 if (GSS_ERROR(status)) 718 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 719 else 720 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 721 722 packet_put_string(send_tok.value, send_tok.length); 723 packet_send(); 724 gss_release_buffer(&ms, &send_tok); 725 } 726 727 if (status == GSS_S_COMPLETE) { 728 /* send either complete or MIC, depending on mechanism */ 729 if (!(flags & GSS_C_INTEG_FLAG)) { 730 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 731 packet_send(); 732 } else { 733 ssh_gssapi_buildmic(&b, authctxt->server_user, 734 authctxt->service, "gssapi-with-mic"); 735 736 gssbuf.value = buffer_ptr(&b); 737 gssbuf.length = buffer_len(&b); 738 739 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 740 741 if (!GSS_ERROR(status)) { 742 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 743 packet_put_string(mic.value, mic.length); 744 745 packet_send(); 746 } 747 748 buffer_free(&b); 749 gss_release_buffer(&ms, &mic); 750 } 751 } 752 753 return status; 754 } 755 756 /* ARGSUSED */ 757 int 758 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 759 { 760 Authctxt *authctxt = ctxt; 761 Gssctxt *gssctxt; 762 int oidlen; 763 char *oidv; 764 765 if (authctxt == NULL) 766 fatal("input_gssapi_response: no authentication context"); 767 gssctxt = authctxt->methoddata; 768 769 /* Setup our OID */ 770 oidv = packet_get_string(&oidlen); 771 772 if (oidlen <= 2 || 773 oidv[0] != SSH_GSS_OIDTYPE || 774 oidv[1] != oidlen - 2) { 775 free(oidv); 776 debug("Badly encoded mechanism OID received"); 777 userauth(authctxt, NULL); 778 return 0; 779 } 780 781 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 782 fatal("Server returned different OID than expected"); 783 784 packet_check_eom(); 785 786 free(oidv); 787 788 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 789 /* Start again with next method on list */ 790 debug("Trying to start again"); 791 userauth(authctxt, NULL); 792 return 0; 793 } 794 return 0; 795 } 796 797 /* ARGSUSED */ 798 int 799 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 800 { 801 Authctxt *authctxt = ctxt; 802 gss_buffer_desc recv_tok; 803 OM_uint32 status; 804 u_int slen; 805 806 if (authctxt == NULL) 807 fatal("input_gssapi_response: no authentication context"); 808 809 recv_tok.value = packet_get_string(&slen); 810 recv_tok.length = slen; /* safe typecast */ 811 812 packet_check_eom(); 813 814 status = process_gssapi_token(ctxt, &recv_tok); 815 816 free(recv_tok.value); 817 818 if (GSS_ERROR(status)) { 819 /* Start again with the next method in the list */ 820 userauth(authctxt, NULL); 821 return 0; 822 } 823 return 0; 824 } 825 826 /* ARGSUSED */ 827 int 828 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 829 { 830 Authctxt *authctxt = ctxt; 831 Gssctxt *gssctxt; 832 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 833 gss_buffer_desc recv_tok; 834 OM_uint32 ms; 835 u_int len; 836 837 if (authctxt == NULL) 838 fatal("input_gssapi_response: no authentication context"); 839 gssctxt = authctxt->methoddata; 840 841 recv_tok.value = packet_get_string(&len); 842 recv_tok.length = len; 843 844 packet_check_eom(); 845 846 /* Stick it into GSSAPI and see what it says */ 847 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 848 &recv_tok, &send_tok, NULL); 849 850 free(recv_tok.value); 851 gss_release_buffer(&ms, &send_tok); 852 853 /* Server will be returning a failed packet after this one */ 854 return 0; 855 } 856 857 /* ARGSUSED */ 858 int 859 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 860 { 861 char *msg; 862 char *lang; 863 864 /* maj */(void)packet_get_int(); 865 /* min */(void)packet_get_int(); 866 msg=packet_get_string(NULL); 867 lang=packet_get_string(NULL); 868 869 packet_check_eom(); 870 871 debug("Server GSSAPI Error:\n%s", msg); 872 free(msg); 873 free(lang); 874 return 0; 875 } 876 #endif /* GSSAPI */ 877 878 int 879 userauth_none(Authctxt *authctxt) 880 { 881 /* initial userauth request */ 882 packet_start(SSH2_MSG_USERAUTH_REQUEST); 883 packet_put_cstring(authctxt->server_user); 884 packet_put_cstring(authctxt->service); 885 packet_put_cstring(authctxt->method->name); 886 packet_send(); 887 return 1; 888 } 889 890 int 891 userauth_passwd(Authctxt *authctxt) 892 { 893 static int attempt = 0; 894 char prompt[150]; 895 char *password; 896 const char *host = options.host_key_alias ? options.host_key_alias : 897 authctxt->host; 898 899 if (attempt++ >= options.number_of_password_prompts) 900 return 0; 901 902 if (attempt != 1) 903 error("Permission denied, please try again."); 904 905 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 906 authctxt->server_user, host); 907 password = read_passphrase(prompt, 0); 908 packet_start(SSH2_MSG_USERAUTH_REQUEST); 909 packet_put_cstring(authctxt->server_user); 910 packet_put_cstring(authctxt->service); 911 packet_put_cstring(authctxt->method->name); 912 packet_put_char(0); 913 packet_put_cstring(password); 914 explicit_bzero(password, strlen(password)); 915 free(password); 916 packet_add_padding(64); 917 packet_send(); 918 919 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 920 &input_userauth_passwd_changereq); 921 922 return 1; 923 } 924 925 /* 926 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 927 */ 928 /* ARGSUSED */ 929 int 930 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 931 { 932 Authctxt *authctxt = ctxt; 933 char *info, *lang, *password = NULL, *retype = NULL; 934 char prompt[150]; 935 const char *host = options.host_key_alias ? options.host_key_alias : 936 authctxt->host; 937 938 debug2("input_userauth_passwd_changereq"); 939 940 if (authctxt == NULL) 941 fatal("input_userauth_passwd_changereq: " 942 "no authentication context"); 943 944 info = packet_get_string(NULL); 945 lang = packet_get_string(NULL); 946 if (strlen(info) > 0) 947 logit("%s", info); 948 free(info); 949 free(lang); 950 packet_start(SSH2_MSG_USERAUTH_REQUEST); 951 packet_put_cstring(authctxt->server_user); 952 packet_put_cstring(authctxt->service); 953 packet_put_cstring(authctxt->method->name); 954 packet_put_char(1); /* additional info */ 955 snprintf(prompt, sizeof(prompt), 956 "Enter %.30s@%.128s's old password: ", 957 authctxt->server_user, host); 958 password = read_passphrase(prompt, 0); 959 packet_put_cstring(password); 960 explicit_bzero(password, strlen(password)); 961 free(password); 962 password = NULL; 963 while (password == NULL) { 964 snprintf(prompt, sizeof(prompt), 965 "Enter %.30s@%.128s's new password: ", 966 authctxt->server_user, host); 967 password = read_passphrase(prompt, RP_ALLOW_EOF); 968 if (password == NULL) { 969 /* bail out */ 970 return 0; 971 } 972 snprintf(prompt, sizeof(prompt), 973 "Retype %.30s@%.128s's new password: ", 974 authctxt->server_user, host); 975 retype = read_passphrase(prompt, 0); 976 if (strcmp(password, retype) != 0) { 977 explicit_bzero(password, strlen(password)); 978 free(password); 979 logit("Mismatch; try again, EOF to quit."); 980 password = NULL; 981 } 982 explicit_bzero(retype, strlen(retype)); 983 free(retype); 984 } 985 packet_put_cstring(password); 986 explicit_bzero(password, strlen(password)); 987 free(password); 988 packet_add_padding(64); 989 packet_send(); 990 991 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 992 &input_userauth_passwd_changereq); 993 return 0; 994 } 995 996 static const char * 997 identity_sign_encode(struct identity *id) 998 { 999 struct ssh *ssh = active_state; 1000 1001 if (id->key->type == KEY_RSA) { 1002 switch (ssh->kex->rsa_sha2) { 1003 case 256: 1004 return "rsa-sha2-256"; 1005 case 512: 1006 return "rsa-sha2-512"; 1007 } 1008 } 1009 return key_ssh_name(id->key); 1010 } 1011 1012 static int 1013 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1014 const u_char *data, size_t datalen, u_int compat) 1015 { 1016 Key *prv; 1017 int ret; 1018 const char *alg; 1019 1020 alg = identity_sign_encode(id); 1021 1022 /* the agent supports this key */ 1023 if (id->agent_fd != -1) 1024 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1025 data, datalen, alg, compat); 1026 1027 /* 1028 * we have already loaded the private key or 1029 * the private key is stored in external hardware 1030 */ 1031 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 1032 return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg, 1033 compat)); 1034 /* load the private key from the file */ 1035 if ((prv = load_identity_file(id)) == NULL) 1036 return SSH_ERR_KEY_NOT_FOUND; 1037 ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1038 sshkey_free(prv); 1039 return (ret); 1040 } 1041 1042 static int 1043 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1044 { 1045 Buffer b; 1046 Identity *private_id; 1047 u_char *blob, *signature; 1048 size_t slen; 1049 u_int bloblen, skip = 0; 1050 int matched, ret = -1, have_sig = 1; 1051 char *fp; 1052 1053 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1054 SSH_FP_DEFAULT)) == NULL) 1055 return 0; 1056 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1057 free(fp); 1058 1059 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1060 /* we cannot handle this key */ 1061 debug3("sign_and_send_pubkey: cannot handle key"); 1062 return 0; 1063 } 1064 /* data to be signed */ 1065 buffer_init(&b); 1066 if (datafellows & SSH_OLD_SESSIONID) { 1067 buffer_append(&b, session_id2, session_id2_len); 1068 skip = session_id2_len; 1069 } else { 1070 buffer_put_string(&b, session_id2, session_id2_len); 1071 skip = buffer_len(&b); 1072 } 1073 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1074 buffer_put_cstring(&b, authctxt->server_user); 1075 buffer_put_cstring(&b, 1076 datafellows & SSH_BUG_PKSERVICE ? 1077 "ssh-userauth" : 1078 authctxt->service); 1079 if (datafellows & SSH_BUG_PKAUTH) { 1080 buffer_put_char(&b, have_sig); 1081 } else { 1082 buffer_put_cstring(&b, authctxt->method->name); 1083 buffer_put_char(&b, have_sig); 1084 buffer_put_cstring(&b, identity_sign_encode(id)); 1085 } 1086 buffer_put_string(&b, blob, bloblen); 1087 1088 /* 1089 * If the key is an certificate, try to find a matching private key 1090 * and use it to complete the signature. 1091 * If no such private key exists, fall back to trying the certificate 1092 * key itself in case it has a private half already loaded. 1093 */ 1094 if (key_is_cert(id->key)) { 1095 matched = 0; 1096 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1097 if (sshkey_equal_public(id->key, private_id->key) && 1098 id->key->type != private_id->key->type) { 1099 id = private_id; 1100 matched = 1; 1101 break; 1102 } 1103 } 1104 if (matched) { 1105 debug2("%s: using private key \"%s\"%s for " 1106 "certificate", __func__, id->filename, 1107 id->agent_fd != -1 ? " from agent" : ""); 1108 } else { 1109 debug("%s: no separate private key for certificate " 1110 "\"%s\"", __func__, id->filename); 1111 } 1112 } 1113 1114 /* generate signature */ 1115 ret = identity_sign(id, &signature, &slen, 1116 buffer_ptr(&b), buffer_len(&b), datafellows); 1117 if (ret != 0) { 1118 if (ret != SSH_ERR_KEY_NOT_FOUND) 1119 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1120 free(blob); 1121 buffer_free(&b); 1122 return 0; 1123 } 1124 #ifdef DEBUG_PK 1125 buffer_dump(&b); 1126 #endif 1127 if (datafellows & SSH_BUG_PKSERVICE) { 1128 buffer_clear(&b); 1129 buffer_append(&b, session_id2, session_id2_len); 1130 skip = session_id2_len; 1131 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1132 buffer_put_cstring(&b, authctxt->server_user); 1133 buffer_put_cstring(&b, authctxt->service); 1134 buffer_put_cstring(&b, authctxt->method->name); 1135 buffer_put_char(&b, have_sig); 1136 if (!(datafellows & SSH_BUG_PKAUTH)) 1137 buffer_put_cstring(&b, key_ssh_name(id->key)); 1138 buffer_put_string(&b, blob, bloblen); 1139 } 1140 free(blob); 1141 1142 /* append signature */ 1143 buffer_put_string(&b, signature, slen); 1144 free(signature); 1145 1146 /* skip session id and packet type */ 1147 if (buffer_len(&b) < skip + 1) 1148 fatal("userauth_pubkey: internal error"); 1149 buffer_consume(&b, skip + 1); 1150 1151 /* put remaining data from buffer into packet */ 1152 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1153 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1154 buffer_free(&b); 1155 packet_send(); 1156 1157 return 1; 1158 } 1159 1160 static int 1161 send_pubkey_test(Authctxt *authctxt, Identity *id) 1162 { 1163 u_char *blob; 1164 u_int bloblen, have_sig = 0; 1165 1166 debug3("send_pubkey_test"); 1167 1168 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1169 /* we cannot handle this key */ 1170 debug3("send_pubkey_test: cannot handle key"); 1171 return 0; 1172 } 1173 /* register callback for USERAUTH_PK_OK message */ 1174 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1175 1176 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1177 packet_put_cstring(authctxt->server_user); 1178 packet_put_cstring(authctxt->service); 1179 packet_put_cstring(authctxt->method->name); 1180 packet_put_char(have_sig); 1181 if (!(datafellows & SSH_BUG_PKAUTH)) 1182 packet_put_cstring(identity_sign_encode(id)); 1183 packet_put_string(blob, bloblen); 1184 free(blob); 1185 packet_send(); 1186 return 1; 1187 } 1188 1189 static Key * 1190 load_identity_file(Identity *id) 1191 { 1192 Key *private = NULL; 1193 char prompt[300], *passphrase, *comment; 1194 int r, perm_ok = 0, quit = 0, i; 1195 struct stat st; 1196 1197 if (stat(id->filename, &st) < 0) { 1198 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1199 id->filename, strerror(errno)); 1200 return NULL; 1201 } 1202 snprintf(prompt, sizeof prompt, 1203 "Enter passphrase for key '%.100s': ", id->filename); 1204 for (i = 0; i <= options.number_of_password_prompts; i++) { 1205 if (i == 0) 1206 passphrase = ""; 1207 else { 1208 passphrase = read_passphrase(prompt, 0); 1209 if (*passphrase == '\0') { 1210 debug2("no passphrase given, try next key"); 1211 free(passphrase); 1212 break; 1213 } 1214 } 1215 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1216 passphrase, &private, &comment, &perm_ok))) { 1217 case 0: 1218 break; 1219 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1220 if (options.batch_mode) { 1221 quit = 1; 1222 break; 1223 } 1224 if (i != 0) 1225 debug2("bad passphrase given, try again..."); 1226 break; 1227 case SSH_ERR_SYSTEM_ERROR: 1228 if (errno == ENOENT) { 1229 debug2("Load key \"%s\": %s", 1230 id->filename, ssh_err(r)); 1231 quit = 1; 1232 break; 1233 } 1234 /* FALLTHROUGH */ 1235 default: 1236 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1237 quit = 1; 1238 break; 1239 } 1240 if (!quit && private != NULL && id->agent_fd == -1 && 1241 !(id->key && id->isprivate)) 1242 maybe_add_key_to_agent(id->filename, private, comment, 1243 passphrase); 1244 if (i > 0) { 1245 explicit_bzero(passphrase, strlen(passphrase)); 1246 free(passphrase); 1247 } 1248 free(comment); 1249 if (private != NULL || quit) 1250 break; 1251 } 1252 return private; 1253 } 1254 1255 /* 1256 * try keys in the following order: 1257 * 1. certificates listed in the config file 1258 * 2. other input certificates 1259 * 3. agent keys that are found in the config file 1260 * 4. other agent keys 1261 * 5. keys that are only listed in the config file 1262 */ 1263 static void 1264 pubkey_prepare(Authctxt *authctxt) 1265 { 1266 struct identity *id, *id2, *tmp; 1267 struct idlist agent, files, *preferred; 1268 struct sshkey *key; 1269 int agent_fd = -1, i, r, found; 1270 size_t j; 1271 struct ssh_identitylist *idlist; 1272 1273 TAILQ_INIT(&agent); /* keys from the agent */ 1274 TAILQ_INIT(&files); /* keys from the config file */ 1275 preferred = &authctxt->keys; 1276 TAILQ_INIT(preferred); /* preferred order of keys */ 1277 1278 /* list of keys stored in the filesystem and PKCS#11 */ 1279 for (i = 0; i < options.num_identity_files; i++) { 1280 key = options.identity_keys[i]; 1281 if (key && key->type == KEY_RSA1) 1282 continue; 1283 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1284 continue; 1285 options.identity_keys[i] = NULL; 1286 id = xcalloc(1, sizeof(*id)); 1287 id->agent_fd = -1; 1288 id->key = key; 1289 id->filename = xstrdup(options.identity_files[i]); 1290 id->userprovided = options.identity_file_userprovided[i]; 1291 TAILQ_INSERT_TAIL(&files, id, next); 1292 } 1293 /* list of certificates specified by user */ 1294 for (i = 0; i < options.num_certificate_files; i++) { 1295 key = options.certificates[i]; 1296 if (!key_is_cert(key) || key->cert == NULL || 1297 key->cert->type != SSH2_CERT_TYPE_USER) 1298 continue; 1299 id = xcalloc(1, sizeof(*id)); 1300 id->agent_fd = -1; 1301 id->key = key; 1302 id->filename = xstrdup(options.certificate_files[i]); 1303 id->userprovided = options.certificate_file_userprovided[i]; 1304 TAILQ_INSERT_TAIL(preferred, id, next); 1305 } 1306 /* list of keys supported by the agent */ 1307 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1308 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1309 debug("%s: ssh_get_authentication_socket: %s", 1310 __func__, ssh_err(r)); 1311 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1312 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1313 debug("%s: ssh_fetch_identitylist: %s", 1314 __func__, ssh_err(r)); 1315 close(agent_fd); 1316 } else { 1317 for (j = 0; j < idlist->nkeys; j++) { 1318 found = 0; 1319 TAILQ_FOREACH(id, &files, next) { 1320 /* 1321 * agent keys from the config file are 1322 * preferred 1323 */ 1324 if (sshkey_equal(idlist->keys[j], id->key)) { 1325 TAILQ_REMOVE(&files, id, next); 1326 TAILQ_INSERT_TAIL(preferred, id, next); 1327 id->agent_fd = agent_fd; 1328 found = 1; 1329 break; 1330 } 1331 } 1332 if (!found && !options.identities_only) { 1333 id = xcalloc(1, sizeof(*id)); 1334 /* XXX "steals" key/comment from idlist */ 1335 id->key = idlist->keys[j]; 1336 id->filename = idlist->comments[j]; 1337 idlist->keys[j] = NULL; 1338 idlist->comments[j] = NULL; 1339 id->agent_fd = agent_fd; 1340 TAILQ_INSERT_TAIL(&agent, id, next); 1341 } 1342 } 1343 ssh_free_identitylist(idlist); 1344 /* append remaining agent keys */ 1345 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1346 TAILQ_REMOVE(&agent, id, next); 1347 TAILQ_INSERT_TAIL(preferred, id, next); 1348 } 1349 authctxt->agent_fd = agent_fd; 1350 } 1351 /* Prefer PKCS11 keys that are explicitly listed */ 1352 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1353 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1354 continue; 1355 found = 0; 1356 TAILQ_FOREACH(id2, &files, next) { 1357 if (id2->key == NULL || 1358 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1359 continue; 1360 if (sshkey_equal(id->key, id2->key)) { 1361 TAILQ_REMOVE(&files, id, next); 1362 TAILQ_INSERT_TAIL(preferred, id, next); 1363 found = 1; 1364 break; 1365 } 1366 } 1367 /* If IdentitiesOnly set and key not found then don't use it */ 1368 if (!found && options.identities_only) { 1369 TAILQ_REMOVE(&files, id, next); 1370 explicit_bzero(id, sizeof(*id)); 1371 free(id); 1372 } 1373 } 1374 /* append remaining keys from the config file */ 1375 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1376 TAILQ_REMOVE(&files, id, next); 1377 TAILQ_INSERT_TAIL(preferred, id, next); 1378 } 1379 /* finally, filter by PubkeyAcceptedKeyTypes */ 1380 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1381 if (id->key != NULL && 1382 match_pattern_list(sshkey_ssh_name(id->key), 1383 options.pubkey_key_types, 0) != 1) { 1384 debug("Skipping %s key %s - " 1385 "not in PubkeyAcceptedKeyTypes", 1386 sshkey_ssh_name(id->key), id->filename); 1387 TAILQ_REMOVE(preferred, id, next); 1388 sshkey_free(id->key); 1389 free(id->filename); 1390 memset(id, 0, sizeof(*id)); 1391 continue; 1392 } 1393 debug2("key: %s (%p)%s%s", id->filename, id->key, 1394 id->userprovided ? ", explicit" : "", 1395 id->agent_fd != -1 ? ", agent" : ""); 1396 } 1397 } 1398 1399 static void 1400 pubkey_cleanup(Authctxt *authctxt) 1401 { 1402 Identity *id; 1403 1404 if (authctxt->agent_fd != -1) 1405 ssh_close_authentication_socket(authctxt->agent_fd); 1406 for (id = TAILQ_FIRST(&authctxt->keys); id; 1407 id = TAILQ_FIRST(&authctxt->keys)) { 1408 TAILQ_REMOVE(&authctxt->keys, id, next); 1409 sshkey_free(id->key); 1410 free(id->filename); 1411 free(id); 1412 } 1413 } 1414 1415 static int 1416 try_identity(Identity *id) 1417 { 1418 if (!id->key) 1419 return (0); 1420 if (key_type_plain(id->key->type) == KEY_RSA && 1421 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1422 debug("Skipped %s key %s for RSA/MD5 server", 1423 key_type(id->key), id->filename); 1424 return (0); 1425 } 1426 return (id->key->type != KEY_RSA1); 1427 } 1428 1429 int 1430 userauth_pubkey(Authctxt *authctxt) 1431 { 1432 Identity *id; 1433 int sent = 0; 1434 1435 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1436 if (id->tried++) 1437 return (0); 1438 /* move key to the end of the queue */ 1439 TAILQ_REMOVE(&authctxt->keys, id, next); 1440 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1441 /* 1442 * send a test message if we have the public key. for 1443 * encrypted keys we cannot do this and have to load the 1444 * private key instead 1445 */ 1446 if (id->key != NULL) { 1447 if (try_identity(id)) { 1448 debug("Offering %s public key: %s", 1449 key_type(id->key), id->filename); 1450 sent = send_pubkey_test(authctxt, id); 1451 } 1452 } else { 1453 debug("Trying private key: %s", id->filename); 1454 id->key = load_identity_file(id); 1455 if (id->key != NULL) { 1456 if (try_identity(id)) { 1457 id->isprivate = 1; 1458 sent = sign_and_send_pubkey( 1459 authctxt, id); 1460 } 1461 key_free(id->key); 1462 id->key = NULL; 1463 } 1464 } 1465 if (sent) 1466 return (sent); 1467 } 1468 return (0); 1469 } 1470 1471 /* 1472 * Send userauth request message specifying keyboard-interactive method. 1473 */ 1474 int 1475 userauth_kbdint(Authctxt *authctxt) 1476 { 1477 static int attempt = 0; 1478 1479 if (attempt++ >= options.number_of_password_prompts) 1480 return 0; 1481 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1482 if (attempt > 1 && !authctxt->info_req_seen) { 1483 debug3("userauth_kbdint: disable: no info_req_seen"); 1484 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1485 return 0; 1486 } 1487 1488 debug2("userauth_kbdint"); 1489 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1490 packet_put_cstring(authctxt->server_user); 1491 packet_put_cstring(authctxt->service); 1492 packet_put_cstring(authctxt->method->name); 1493 packet_put_cstring(""); /* lang */ 1494 packet_put_cstring(options.kbd_interactive_devices ? 1495 options.kbd_interactive_devices : ""); 1496 packet_send(); 1497 1498 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1499 return 1; 1500 } 1501 1502 /* 1503 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1504 */ 1505 int 1506 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1507 { 1508 Authctxt *authctxt = ctxt; 1509 char *name, *inst, *lang, *prompt, *response; 1510 u_int num_prompts, i; 1511 int echo = 0; 1512 1513 debug2("input_userauth_info_req"); 1514 1515 if (authctxt == NULL) 1516 fatal("input_userauth_info_req: no authentication context"); 1517 1518 authctxt->info_req_seen = 1; 1519 1520 name = packet_get_string(NULL); 1521 inst = packet_get_string(NULL); 1522 lang = packet_get_string(NULL); 1523 if (strlen(name) > 0) 1524 logit("%s", name); 1525 if (strlen(inst) > 0) 1526 logit("%s", inst); 1527 free(name); 1528 free(inst); 1529 free(lang); 1530 1531 num_prompts = packet_get_int(); 1532 /* 1533 * Begin to build info response packet based on prompts requested. 1534 * We commit to providing the correct number of responses, so if 1535 * further on we run into a problem that prevents this, we have to 1536 * be sure and clean this up and send a correct error response. 1537 */ 1538 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1539 packet_put_int(num_prompts); 1540 1541 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1542 for (i = 0; i < num_prompts; i++) { 1543 prompt = packet_get_string(NULL); 1544 echo = packet_get_char(); 1545 1546 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1547 1548 packet_put_cstring(response); 1549 explicit_bzero(response, strlen(response)); 1550 free(response); 1551 free(prompt); 1552 } 1553 packet_check_eom(); /* done with parsing incoming message. */ 1554 1555 packet_add_padding(64); 1556 packet_send(); 1557 return 0; 1558 } 1559 1560 static int 1561 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1562 const u_char *data, size_t datalen) 1563 { 1564 struct sshbuf *b; 1565 struct stat st; 1566 pid_t pid; 1567 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1568 u_char rversion = 0, version = 2; 1569 void (*osigchld)(int); 1570 1571 *sigp = NULL; 1572 *lenp = 0; 1573 1574 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1575 error("%s: not installed: %s", __func__, strerror(errno)); 1576 return -1; 1577 } 1578 if (fflush(stdout) != 0) { 1579 error("%s: fflush: %s", __func__, strerror(errno)); 1580 return -1; 1581 } 1582 if (pipe(to) < 0) { 1583 error("%s: pipe: %s", __func__, strerror(errno)); 1584 return -1; 1585 } 1586 if (pipe(from) < 0) { 1587 error("%s: pipe: %s", __func__, strerror(errno)); 1588 return -1; 1589 } 1590 if ((pid = fork()) < 0) { 1591 error("%s: fork: %s", __func__, strerror(errno)); 1592 return -1; 1593 } 1594 osigchld = signal(SIGCHLD, SIG_DFL); 1595 if (pid == 0) { 1596 /* keep the socket on exec */ 1597 fcntl(sock, F_SETFD, 0); 1598 permanently_drop_suid(getuid()); 1599 close(from[0]); 1600 if (dup2(from[1], STDOUT_FILENO) < 0) 1601 fatal("%s: dup2: %s", __func__, strerror(errno)); 1602 close(to[1]); 1603 if (dup2(to[0], STDIN_FILENO) < 0) 1604 fatal("%s: dup2: %s", __func__, strerror(errno)); 1605 close(from[1]); 1606 close(to[0]); 1607 /* Close everything but stdio and the socket */ 1608 for (i = STDERR_FILENO + 1; i < sock; i++) 1609 close(i); 1610 closefrom(sock + 1); 1611 debug3("%s: [child] pid=%ld, exec %s", 1612 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1613 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1614 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1615 strerror(errno)); 1616 } 1617 close(from[1]); 1618 close(to[0]); 1619 1620 if ((b = sshbuf_new()) == NULL) 1621 fatal("%s: sshbuf_new failed", __func__); 1622 /* send # of sock, data to be signed */ 1623 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1624 (r = sshbuf_put_string(b, data, datalen)) != 0) 1625 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1626 if (ssh_msg_send(to[1], version, b) == -1) 1627 fatal("%s: couldn't send request", __func__); 1628 sshbuf_reset(b); 1629 r = ssh_msg_recv(from[0], b); 1630 close(from[0]); 1631 close(to[1]); 1632 if (r < 0) { 1633 error("%s: no reply", __func__); 1634 goto fail; 1635 } 1636 1637 errno = 0; 1638 while (waitpid(pid, &status, 0) < 0) { 1639 if (errno != EINTR) { 1640 error("%s: waitpid %ld: %s", 1641 __func__, (long)pid, strerror(errno)); 1642 goto fail; 1643 } 1644 } 1645 if (!WIFEXITED(status)) { 1646 error("%s: exited abnormally", __func__); 1647 goto fail; 1648 } 1649 if (WEXITSTATUS(status) != 0) { 1650 error("%s: exited with status %d", 1651 __func__, WEXITSTATUS(status)); 1652 goto fail; 1653 } 1654 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1655 error("%s: buffer error: %s", __func__, ssh_err(r)); 1656 goto fail; 1657 } 1658 if (rversion != version) { 1659 error("%s: bad version", __func__); 1660 goto fail; 1661 } 1662 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1663 error("%s: buffer error: %s", __func__, ssh_err(r)); 1664 fail: 1665 signal(SIGCHLD, osigchld); 1666 sshbuf_free(b); 1667 return -1; 1668 } 1669 signal(SIGCHLD, osigchld); 1670 sshbuf_free(b); 1671 1672 return 0; 1673 } 1674 1675 int 1676 userauth_hostbased(Authctxt *authctxt) 1677 { 1678 struct ssh *ssh = active_state; 1679 struct sshkey *private = NULL; 1680 struct sshbuf *b = NULL; 1681 const char *service; 1682 u_char *sig = NULL, *keyblob = NULL; 1683 char *fp = NULL, *chost = NULL, *lname = NULL; 1684 size_t siglen = 0, keylen = 0; 1685 int i, r, success = 0; 1686 1687 if (authctxt->ktypes == NULL) { 1688 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1689 authctxt->ktypes = authctxt->oktypes; 1690 } 1691 1692 /* 1693 * Work through each listed type pattern in HostbasedKeyTypes, 1694 * trying each hostkey that matches the type in turn. 1695 */ 1696 for (;;) { 1697 if (authctxt->active_ktype == NULL) 1698 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1699 if (authctxt->active_ktype == NULL || 1700 *authctxt->active_ktype == '\0') 1701 break; 1702 debug3("%s: trying key type %s", __func__, 1703 authctxt->active_ktype); 1704 1705 /* check for a useful key */ 1706 private = NULL; 1707 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1708 if (authctxt->sensitive->keys[i] == NULL || 1709 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1710 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1711 continue; 1712 if (match_pattern_list( 1713 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1714 authctxt->active_ktype, 0) != 1) 1715 continue; 1716 /* we take and free the key */ 1717 private = authctxt->sensitive->keys[i]; 1718 authctxt->sensitive->keys[i] = NULL; 1719 break; 1720 } 1721 /* Found one */ 1722 if (private != NULL) 1723 break; 1724 /* No more keys of this type; advance */ 1725 authctxt->active_ktype = NULL; 1726 } 1727 if (private == NULL) { 1728 free(authctxt->oktypes); 1729 authctxt->oktypes = authctxt->ktypes = NULL; 1730 authctxt->active_ktype = NULL; 1731 debug("No more client hostkeys for hostbased authentication."); 1732 goto out; 1733 } 1734 1735 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1736 SSH_FP_DEFAULT)) == NULL) { 1737 error("%s: sshkey_fingerprint failed", __func__); 1738 goto out; 1739 } 1740 debug("%s: trying hostkey %s %s", 1741 __func__, sshkey_ssh_name(private), fp); 1742 1743 /* figure out a name for the client host */ 1744 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1745 error("%s: cannot get local ipaddr/name", __func__); 1746 goto out; 1747 } 1748 1749 /* XXX sshbuf_put_stringf? */ 1750 xasprintf(&chost, "%s.", lname); 1751 debug2("%s: chost %s", __func__, chost); 1752 1753 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1754 authctxt->service; 1755 1756 /* construct data */ 1757 if ((b = sshbuf_new()) == NULL) { 1758 error("%s: sshbuf_new failed", __func__); 1759 goto out; 1760 } 1761 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1762 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1763 goto out; 1764 } 1765 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1766 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1767 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1768 (r = sshbuf_put_cstring(b, service)) != 0 || 1769 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1770 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1771 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1772 (r = sshbuf_put_cstring(b, chost)) != 0 || 1773 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1774 error("%s: buffer error: %s", __func__, ssh_err(r)); 1775 goto out; 1776 } 1777 1778 #ifdef DEBUG_PK 1779 sshbuf_dump(b, stderr); 1780 #endif 1781 if (authctxt->sensitive->external_keysign) 1782 r = ssh_keysign(private, &sig, &siglen, 1783 sshbuf_ptr(b), sshbuf_len(b)); 1784 else if ((r = sshkey_sign(private, &sig, &siglen, 1785 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1786 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1787 if (r != 0) { 1788 error("sign using hostkey %s %s failed", 1789 sshkey_ssh_name(private), fp); 1790 goto out; 1791 } 1792 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1793 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1794 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1795 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1796 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1797 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1798 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1799 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1800 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1801 (r = sshpkt_send(ssh)) != 0) { 1802 error("%s: packet error: %s", __func__, ssh_err(r)); 1803 goto out; 1804 } 1805 success = 1; 1806 1807 out: 1808 if (sig != NULL) { 1809 explicit_bzero(sig, siglen); 1810 free(sig); 1811 } 1812 free(keyblob); 1813 free(lname); 1814 free(fp); 1815 free(chost); 1816 sshkey_free(private); 1817 sshbuf_free(b); 1818 1819 return success; 1820 } 1821 1822 /* find auth method */ 1823 1824 /* 1825 * given auth method name, if configurable options permit this method fill 1826 * in auth_ident field and return true, otherwise return false. 1827 */ 1828 static int 1829 authmethod_is_enabled(Authmethod *method) 1830 { 1831 if (method == NULL) 1832 return 0; 1833 /* return false if options indicate this method is disabled */ 1834 if (method->enabled == NULL || *method->enabled == 0) 1835 return 0; 1836 /* return false if batch mode is enabled but method needs interactive mode */ 1837 if (method->batch_flag != NULL && *method->batch_flag != 0) 1838 return 0; 1839 return 1; 1840 } 1841 1842 static Authmethod * 1843 authmethod_lookup(const char *name) 1844 { 1845 Authmethod *method = NULL; 1846 if (name != NULL) 1847 for (method = authmethods; method->name != NULL; method++) 1848 if (strcmp(name, method->name) == 0) 1849 return method; 1850 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1851 return NULL; 1852 } 1853 1854 /* XXX internal state */ 1855 static Authmethod *current = NULL; 1856 static char *supported = NULL; 1857 static char *preferred = NULL; 1858 1859 /* 1860 * Given the authentication method list sent by the server, return the 1861 * next method we should try. If the server initially sends a nil list, 1862 * use a built-in default list. 1863 */ 1864 static Authmethod * 1865 authmethod_get(char *authlist) 1866 { 1867 char *name = NULL; 1868 u_int next; 1869 1870 /* Use a suitable default if we're passed a nil list. */ 1871 if (authlist == NULL || strlen(authlist) == 0) 1872 authlist = options.preferred_authentications; 1873 1874 if (supported == NULL || strcmp(authlist, supported) != 0) { 1875 debug3("start over, passed a different list %s", authlist); 1876 free(supported); 1877 supported = xstrdup(authlist); 1878 preferred = options.preferred_authentications; 1879 debug3("preferred %s", preferred); 1880 current = NULL; 1881 } else if (current != NULL && authmethod_is_enabled(current)) 1882 return current; 1883 1884 for (;;) { 1885 if ((name = match_list(preferred, supported, &next)) == NULL) { 1886 debug("No more authentication methods to try."); 1887 current = NULL; 1888 return NULL; 1889 } 1890 preferred += next; 1891 debug3("authmethod_lookup %s", name); 1892 debug3("remaining preferred: %s", preferred); 1893 if ((current = authmethod_lookup(name)) != NULL && 1894 authmethod_is_enabled(current)) { 1895 debug3("authmethod_is_enabled %s", name); 1896 debug("Next authentication method: %s", name); 1897 free(name); 1898 return current; 1899 } 1900 free(name); 1901 } 1902 } 1903 1904 static char * 1905 authmethods_get(void) 1906 { 1907 Authmethod *method = NULL; 1908 Buffer b; 1909 char *list; 1910 1911 buffer_init(&b); 1912 for (method = authmethods; method->name != NULL; method++) { 1913 if (authmethod_is_enabled(method)) { 1914 if (buffer_len(&b) > 0) 1915 buffer_append(&b, ",", 1); 1916 buffer_append(&b, method->name, strlen(method->name)); 1917 } 1918 } 1919 if ((list = sshbuf_dup_string(&b)) == NULL) 1920 fatal("%s: sshbuf_dup_string failed", __func__); 1921 buffer_free(&b); 1922 return list; 1923 } 1924 1925