1 /* $OpenBSD: sshconnect2.c,v 1.251 2016/12/04 23:54:02 djm 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 void pubkey_reset(Authctxt *); 322 static Key *load_identity_file(Identity *); 323 324 static Authmethod *authmethod_get(char *authlist); 325 static Authmethod *authmethod_lookup(const char *name); 326 static char *authmethods_get(void); 327 328 Authmethod authmethods[] = { 329 #ifdef GSSAPI 330 {"gssapi-with-mic", 331 userauth_gssapi, 332 NULL, 333 &options.gss_authentication, 334 NULL}, 335 #endif 336 {"hostbased", 337 userauth_hostbased, 338 NULL, 339 &options.hostbased_authentication, 340 NULL}, 341 {"publickey", 342 userauth_pubkey, 343 NULL, 344 &options.pubkey_authentication, 345 NULL}, 346 {"keyboard-interactive", 347 userauth_kbdint, 348 NULL, 349 &options.kbd_interactive_authentication, 350 &options.batch_mode}, 351 {"password", 352 userauth_passwd, 353 NULL, 354 &options.password_authentication, 355 &options.batch_mode}, 356 {"none", 357 userauth_none, 358 NULL, 359 NULL, 360 NULL}, 361 {NULL, NULL, NULL, NULL, NULL} 362 }; 363 364 void 365 ssh_userauth2(const char *local_user, const char *server_user, char *host, 366 Sensitive *sensitive) 367 { 368 struct ssh *ssh = active_state; 369 Authctxt authctxt; 370 int r; 371 372 if (options.challenge_response_authentication) 373 options.kbd_interactive_authentication = 1; 374 if (options.preferred_authentications == NULL) 375 options.preferred_authentications = authmethods_get(); 376 377 /* setup authentication context */ 378 memset(&authctxt, 0, sizeof(authctxt)); 379 pubkey_prepare(&authctxt); 380 authctxt.server_user = server_user; 381 authctxt.local_user = local_user; 382 authctxt.host = host; 383 authctxt.service = "ssh-connection"; /* service name */ 384 authctxt.success = 0; 385 authctxt.method = authmethod_lookup("none"); 386 authctxt.authlist = NULL; 387 authctxt.methoddata = NULL; 388 authctxt.sensitive = sensitive; 389 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 390 authctxt.info_req_seen = 0; 391 authctxt.agent_fd = -1; 392 if (authctxt.method == NULL) 393 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 394 395 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 396 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 397 (r = sshpkt_send(ssh)) != 0) 398 fatal("%s: %s", __func__, ssh_err(r)); 399 400 ssh_dispatch_init(ssh, &input_userauth_error); 401 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 402 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 403 ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 404 405 pubkey_cleanup(&authctxt); 406 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 407 408 if (!authctxt.success) 409 fatal("Authentication failed."); 410 debug("Authentication succeeded (%s).", authctxt.method->name); 411 } 412 413 /* ARGSUSED */ 414 int 415 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt) 416 { 417 Authctxt *authctxt = ctxt; 418 struct ssh *ssh = active_state; 419 int r; 420 421 if (ssh_packet_remaining(ssh) > 0) { 422 char *reply; 423 424 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 425 goto out; 426 debug2("service_accept: %s", reply); 427 free(reply); 428 } else { 429 debug2("buggy server: service_accept w/o service"); 430 } 431 if ((r = sshpkt_get_end(ssh)) != 0) 432 goto out; 433 debug("SSH2_MSG_SERVICE_ACCEPT received"); 434 435 /* initial userauth request */ 436 userauth_none(authctxt); 437 438 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 439 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 440 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 441 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 442 r = 0; 443 out: 444 return r; 445 } 446 447 /* ARGSUSED */ 448 int 449 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt) 450 { 451 return kex_input_ext_info(type, seqnr, active_state); 452 } 453 454 void 455 userauth(Authctxt *authctxt, char *authlist) 456 { 457 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 458 authctxt->method->cleanup(authctxt); 459 460 free(authctxt->methoddata); 461 authctxt->methoddata = NULL; 462 if (authlist == NULL) { 463 authlist = authctxt->authlist; 464 } else { 465 free(authctxt->authlist); 466 authctxt->authlist = authlist; 467 } 468 for (;;) { 469 Authmethod *method = authmethod_get(authlist); 470 if (method == NULL) 471 fatal("Permission denied (%s).", authlist); 472 authctxt->method = method; 473 474 /* reset the per method handler */ 475 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 476 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 477 478 /* and try new method */ 479 if (method->userauth(authctxt) != 0) { 480 debug2("we sent a %s packet, wait for reply", method->name); 481 break; 482 } else { 483 debug2("we did not send a packet, disable method"); 484 method->enabled = NULL; 485 } 486 } 487 } 488 489 /* ARGSUSED */ 490 int 491 input_userauth_error(int type, u_int32_t seq, void *ctxt) 492 { 493 fatal("input_userauth_error: bad message during authentication: " 494 "type %d", type); 495 return 0; 496 } 497 498 /* ARGSUSED */ 499 int 500 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 501 { 502 char *msg, *lang; 503 u_int len; 504 505 debug3("%s", __func__); 506 msg = packet_get_string(&len); 507 lang = packet_get_string(NULL); 508 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 509 fmprintf(stderr, "%s", msg); 510 free(msg); 511 free(lang); 512 return 0; 513 } 514 515 /* ARGSUSED */ 516 int 517 input_userauth_success(int type, u_int32_t seq, void *ctxt) 518 { 519 Authctxt *authctxt = ctxt; 520 521 if (authctxt == NULL) 522 fatal("input_userauth_success: no authentication context"); 523 free(authctxt->authlist); 524 authctxt->authlist = NULL; 525 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 526 authctxt->method->cleanup(authctxt); 527 free(authctxt->methoddata); 528 authctxt->methoddata = NULL; 529 authctxt->success = 1; /* break out */ 530 return 0; 531 } 532 533 int 534 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 535 { 536 Authctxt *authctxt = ctxt; 537 538 if (authctxt == NULL) 539 fatal("%s: no authentication context", __func__); 540 541 fatal("Unexpected authentication success during %s.", 542 authctxt->method->name); 543 return 0; 544 } 545 546 /* ARGSUSED */ 547 int 548 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 549 { 550 Authctxt *authctxt = ctxt; 551 char *authlist = NULL; 552 int partial; 553 554 if (authctxt == NULL) 555 fatal("input_userauth_failure: no authentication context"); 556 557 authlist = packet_get_string(NULL); 558 partial = packet_get_char(); 559 packet_check_eom(); 560 561 if (partial != 0) { 562 verbose("Authenticated with partial success."); 563 /* reset state */ 564 pubkey_reset(authctxt); 565 } 566 debug("Authentications that can continue: %s", authlist); 567 568 userauth(authctxt, authlist); 569 return 0; 570 } 571 572 /* ARGSUSED */ 573 int 574 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 575 { 576 Authctxt *authctxt = ctxt; 577 Key *key = NULL; 578 Identity *id = NULL; 579 Buffer b; 580 int pktype, sent = 0; 581 u_int alen, blen; 582 char *pkalg, *fp; 583 u_char *pkblob; 584 585 if (authctxt == NULL) 586 fatal("input_userauth_pk_ok: no authentication context"); 587 if (datafellows & SSH_BUG_PKOK) { 588 /* this is similar to SSH_BUG_PKAUTH */ 589 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 590 pkblob = packet_get_string(&blen); 591 buffer_init(&b); 592 buffer_append(&b, pkblob, blen); 593 pkalg = buffer_get_string(&b, &alen); 594 buffer_free(&b); 595 } else { 596 pkalg = packet_get_string(&alen); 597 pkblob = packet_get_string(&blen); 598 } 599 packet_check_eom(); 600 601 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 602 603 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 604 debug("unknown pkalg %s", pkalg); 605 goto done; 606 } 607 if ((key = key_from_blob(pkblob, blen)) == NULL) { 608 debug("no key from blob. pkalg %s", pkalg); 609 goto done; 610 } 611 if (key->type != pktype) { 612 error("input_userauth_pk_ok: type mismatch " 613 "for decoded key (received %d, expected %d)", 614 key->type, pktype); 615 goto done; 616 } 617 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 618 SSH_FP_DEFAULT)) == NULL) 619 goto done; 620 debug2("input_userauth_pk_ok: fp %s", fp); 621 free(fp); 622 623 /* 624 * search keys in the reverse order, because last candidate has been 625 * moved to the end of the queue. this also avoids confusion by 626 * duplicate keys 627 */ 628 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 629 if (key_equal(key, id->key)) { 630 sent = sign_and_send_pubkey(authctxt, id); 631 break; 632 } 633 } 634 done: 635 if (key != NULL) 636 key_free(key); 637 free(pkalg); 638 free(pkblob); 639 640 /* try another method if we did not send a packet */ 641 if (sent == 0) 642 userauth(authctxt, NULL); 643 return 0; 644 } 645 646 #ifdef GSSAPI 647 int 648 userauth_gssapi(Authctxt *authctxt) 649 { 650 Gssctxt *gssctxt = NULL; 651 static gss_OID_set gss_supported = NULL; 652 static u_int mech = 0; 653 OM_uint32 min; 654 int ok = 0; 655 656 /* Try one GSSAPI method at a time, rather than sending them all at 657 * once. */ 658 659 if (gss_supported == NULL) 660 gss_indicate_mechs(&min, &gss_supported); 661 662 /* Check to see if the mechanism is usable before we offer it */ 663 while (mech < gss_supported->count && !ok) { 664 /* My DER encoding requires length<128 */ 665 if (gss_supported->elements[mech].length < 128 && 666 ssh_gssapi_check_mechanism(&gssctxt, 667 &gss_supported->elements[mech], authctxt->host)) { 668 ok = 1; /* Mechanism works */ 669 } else { 670 mech++; 671 } 672 } 673 674 if (!ok) 675 return 0; 676 677 authctxt->methoddata=(void *)gssctxt; 678 679 packet_start(SSH2_MSG_USERAUTH_REQUEST); 680 packet_put_cstring(authctxt->server_user); 681 packet_put_cstring(authctxt->service); 682 packet_put_cstring(authctxt->method->name); 683 684 packet_put_int(1); 685 686 packet_put_int((gss_supported->elements[mech].length) + 2); 687 packet_put_char(SSH_GSS_OIDTYPE); 688 packet_put_char(gss_supported->elements[mech].length); 689 packet_put_raw(gss_supported->elements[mech].elements, 690 gss_supported->elements[mech].length); 691 692 packet_send(); 693 694 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 695 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 696 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 697 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 698 699 mech++; /* Move along to next candidate */ 700 701 return 1; 702 } 703 704 static OM_uint32 705 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 706 { 707 Authctxt *authctxt = ctxt; 708 Gssctxt *gssctxt = authctxt->methoddata; 709 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 710 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 711 gss_buffer_desc gssbuf; 712 OM_uint32 status, ms, flags; 713 Buffer b; 714 715 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 716 recv_tok, &send_tok, &flags); 717 718 if (send_tok.length > 0) { 719 if (GSS_ERROR(status)) 720 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 721 else 722 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 723 724 packet_put_string(send_tok.value, send_tok.length); 725 packet_send(); 726 gss_release_buffer(&ms, &send_tok); 727 } 728 729 if (status == GSS_S_COMPLETE) { 730 /* send either complete or MIC, depending on mechanism */ 731 if (!(flags & GSS_C_INTEG_FLAG)) { 732 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 733 packet_send(); 734 } else { 735 ssh_gssapi_buildmic(&b, authctxt->server_user, 736 authctxt->service, "gssapi-with-mic"); 737 738 gssbuf.value = buffer_ptr(&b); 739 gssbuf.length = buffer_len(&b); 740 741 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 742 743 if (!GSS_ERROR(status)) { 744 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 745 packet_put_string(mic.value, mic.length); 746 747 packet_send(); 748 } 749 750 buffer_free(&b); 751 gss_release_buffer(&ms, &mic); 752 } 753 } 754 755 return status; 756 } 757 758 /* ARGSUSED */ 759 int 760 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 761 { 762 Authctxt *authctxt = ctxt; 763 Gssctxt *gssctxt; 764 int oidlen; 765 char *oidv; 766 767 if (authctxt == NULL) 768 fatal("input_gssapi_response: no authentication context"); 769 gssctxt = authctxt->methoddata; 770 771 /* Setup our OID */ 772 oidv = packet_get_string(&oidlen); 773 774 if (oidlen <= 2 || 775 oidv[0] != SSH_GSS_OIDTYPE || 776 oidv[1] != oidlen - 2) { 777 free(oidv); 778 debug("Badly encoded mechanism OID received"); 779 userauth(authctxt, NULL); 780 return 0; 781 } 782 783 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 784 fatal("Server returned different OID than expected"); 785 786 packet_check_eom(); 787 788 free(oidv); 789 790 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 791 /* Start again with next method on list */ 792 debug("Trying to start again"); 793 userauth(authctxt, NULL); 794 return 0; 795 } 796 return 0; 797 } 798 799 /* ARGSUSED */ 800 int 801 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 802 { 803 Authctxt *authctxt = ctxt; 804 gss_buffer_desc recv_tok; 805 OM_uint32 status; 806 u_int slen; 807 808 if (authctxt == NULL) 809 fatal("input_gssapi_response: no authentication context"); 810 811 recv_tok.value = packet_get_string(&slen); 812 recv_tok.length = slen; /* safe typecast */ 813 814 packet_check_eom(); 815 816 status = process_gssapi_token(ctxt, &recv_tok); 817 818 free(recv_tok.value); 819 820 if (GSS_ERROR(status)) { 821 /* Start again with the next method in the list */ 822 userauth(authctxt, NULL); 823 return 0; 824 } 825 return 0; 826 } 827 828 /* ARGSUSED */ 829 int 830 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 831 { 832 Authctxt *authctxt = ctxt; 833 Gssctxt *gssctxt; 834 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 835 gss_buffer_desc recv_tok; 836 OM_uint32 ms; 837 u_int len; 838 839 if (authctxt == NULL) 840 fatal("input_gssapi_response: no authentication context"); 841 gssctxt = authctxt->methoddata; 842 843 recv_tok.value = packet_get_string(&len); 844 recv_tok.length = len; 845 846 packet_check_eom(); 847 848 /* Stick it into GSSAPI and see what it says */ 849 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 850 &recv_tok, &send_tok, NULL); 851 852 free(recv_tok.value); 853 gss_release_buffer(&ms, &send_tok); 854 855 /* Server will be returning a failed packet after this one */ 856 return 0; 857 } 858 859 /* ARGSUSED */ 860 int 861 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 862 { 863 char *msg; 864 char *lang; 865 866 /* maj */(void)packet_get_int(); 867 /* min */(void)packet_get_int(); 868 msg=packet_get_string(NULL); 869 lang=packet_get_string(NULL); 870 871 packet_check_eom(); 872 873 debug("Server GSSAPI Error:\n%s", msg); 874 free(msg); 875 free(lang); 876 return 0; 877 } 878 #endif /* GSSAPI */ 879 880 int 881 userauth_none(Authctxt *authctxt) 882 { 883 /* initial userauth request */ 884 packet_start(SSH2_MSG_USERAUTH_REQUEST); 885 packet_put_cstring(authctxt->server_user); 886 packet_put_cstring(authctxt->service); 887 packet_put_cstring(authctxt->method->name); 888 packet_send(); 889 return 1; 890 } 891 892 int 893 userauth_passwd(Authctxt *authctxt) 894 { 895 static int attempt = 0; 896 char prompt[150]; 897 char *password; 898 const char *host = options.host_key_alias ? options.host_key_alias : 899 authctxt->host; 900 901 if (attempt++ >= options.number_of_password_prompts) 902 return 0; 903 904 if (attempt != 1) 905 error("Permission denied, please try again."); 906 907 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 908 authctxt->server_user, host); 909 password = read_passphrase(prompt, 0); 910 packet_start(SSH2_MSG_USERAUTH_REQUEST); 911 packet_put_cstring(authctxt->server_user); 912 packet_put_cstring(authctxt->service); 913 packet_put_cstring(authctxt->method->name); 914 packet_put_char(0); 915 packet_put_cstring(password); 916 explicit_bzero(password, strlen(password)); 917 free(password); 918 packet_add_padding(64); 919 packet_send(); 920 921 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 922 &input_userauth_passwd_changereq); 923 924 return 1; 925 } 926 927 /* 928 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 929 */ 930 /* ARGSUSED */ 931 int 932 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 933 { 934 Authctxt *authctxt = ctxt; 935 char *info, *lang, *password = NULL, *retype = NULL; 936 char prompt[150]; 937 const char *host = options.host_key_alias ? options.host_key_alias : 938 authctxt->host; 939 940 debug2("input_userauth_passwd_changereq"); 941 942 if (authctxt == NULL) 943 fatal("input_userauth_passwd_changereq: " 944 "no authentication context"); 945 946 info = packet_get_string(NULL); 947 lang = packet_get_string(NULL); 948 if (strlen(info) > 0) 949 logit("%s", info); 950 free(info); 951 free(lang); 952 packet_start(SSH2_MSG_USERAUTH_REQUEST); 953 packet_put_cstring(authctxt->server_user); 954 packet_put_cstring(authctxt->service); 955 packet_put_cstring(authctxt->method->name); 956 packet_put_char(1); /* additional info */ 957 snprintf(prompt, sizeof(prompt), 958 "Enter %.30s@%.128s's old password: ", 959 authctxt->server_user, host); 960 password = read_passphrase(prompt, 0); 961 packet_put_cstring(password); 962 explicit_bzero(password, strlen(password)); 963 free(password); 964 password = NULL; 965 while (password == NULL) { 966 snprintf(prompt, sizeof(prompt), 967 "Enter %.30s@%.128s's new password: ", 968 authctxt->server_user, host); 969 password = read_passphrase(prompt, RP_ALLOW_EOF); 970 if (password == NULL) { 971 /* bail out */ 972 return 0; 973 } 974 snprintf(prompt, sizeof(prompt), 975 "Retype %.30s@%.128s's new password: ", 976 authctxt->server_user, host); 977 retype = read_passphrase(prompt, 0); 978 if (strcmp(password, retype) != 0) { 979 explicit_bzero(password, strlen(password)); 980 free(password); 981 logit("Mismatch; try again, EOF to quit."); 982 password = NULL; 983 } 984 explicit_bzero(retype, strlen(retype)); 985 free(retype); 986 } 987 packet_put_cstring(password); 988 explicit_bzero(password, strlen(password)); 989 free(password); 990 packet_add_padding(64); 991 packet_send(); 992 993 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 994 &input_userauth_passwd_changereq); 995 return 0; 996 } 997 998 static const char * 999 identity_sign_encode(struct identity *id) 1000 { 1001 struct ssh *ssh = active_state; 1002 1003 if (id->key->type == KEY_RSA) { 1004 switch (ssh->kex->rsa_sha2) { 1005 case 256: 1006 return "rsa-sha2-256"; 1007 case 512: 1008 return "rsa-sha2-512"; 1009 } 1010 } 1011 return key_ssh_name(id->key); 1012 } 1013 1014 static int 1015 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1016 const u_char *data, size_t datalen, u_int compat) 1017 { 1018 Key *prv; 1019 int ret; 1020 const char *alg; 1021 1022 alg = identity_sign_encode(id); 1023 1024 /* the agent supports this key */ 1025 if (id->agent_fd != -1) 1026 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1027 data, datalen, alg, compat); 1028 1029 /* 1030 * we have already loaded the private key or 1031 * the private key is stored in external hardware 1032 */ 1033 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 1034 return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg, 1035 compat)); 1036 /* load the private key from the file */ 1037 if ((prv = load_identity_file(id)) == NULL) 1038 return SSH_ERR_KEY_NOT_FOUND; 1039 ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1040 sshkey_free(prv); 1041 return (ret); 1042 } 1043 1044 static int 1045 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1046 { 1047 Buffer b; 1048 Identity *private_id; 1049 u_char *blob, *signature; 1050 size_t slen; 1051 u_int bloblen, skip = 0; 1052 int matched, ret = -1, have_sig = 1; 1053 char *fp; 1054 1055 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1056 SSH_FP_DEFAULT)) == NULL) 1057 return 0; 1058 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1059 free(fp); 1060 1061 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1062 /* we cannot handle this key */ 1063 debug3("sign_and_send_pubkey: cannot handle key"); 1064 return 0; 1065 } 1066 /* data to be signed */ 1067 buffer_init(&b); 1068 if (datafellows & SSH_OLD_SESSIONID) { 1069 buffer_append(&b, session_id2, session_id2_len); 1070 skip = session_id2_len; 1071 } else { 1072 buffer_put_string(&b, session_id2, session_id2_len); 1073 skip = buffer_len(&b); 1074 } 1075 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1076 buffer_put_cstring(&b, authctxt->server_user); 1077 buffer_put_cstring(&b, 1078 datafellows & SSH_BUG_PKSERVICE ? 1079 "ssh-userauth" : 1080 authctxt->service); 1081 if (datafellows & SSH_BUG_PKAUTH) { 1082 buffer_put_char(&b, have_sig); 1083 } else { 1084 buffer_put_cstring(&b, authctxt->method->name); 1085 buffer_put_char(&b, have_sig); 1086 buffer_put_cstring(&b, identity_sign_encode(id)); 1087 } 1088 buffer_put_string(&b, blob, bloblen); 1089 1090 /* 1091 * If the key is an certificate, try to find a matching private key 1092 * and use it to complete the signature. 1093 * If no such private key exists, fall back to trying the certificate 1094 * key itself in case it has a private half already loaded. 1095 */ 1096 if (key_is_cert(id->key)) { 1097 matched = 0; 1098 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1099 if (sshkey_equal_public(id->key, private_id->key) && 1100 id->key->type != private_id->key->type) { 1101 id = private_id; 1102 matched = 1; 1103 break; 1104 } 1105 } 1106 if (matched) { 1107 debug2("%s: using private key \"%s\"%s for " 1108 "certificate", __func__, id->filename, 1109 id->agent_fd != -1 ? " from agent" : ""); 1110 } else { 1111 debug("%s: no separate private key for certificate " 1112 "\"%s\"", __func__, id->filename); 1113 } 1114 } 1115 1116 /* generate signature */ 1117 ret = identity_sign(id, &signature, &slen, 1118 buffer_ptr(&b), buffer_len(&b), datafellows); 1119 if (ret != 0) { 1120 if (ret != SSH_ERR_KEY_NOT_FOUND) 1121 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1122 free(blob); 1123 buffer_free(&b); 1124 return 0; 1125 } 1126 #ifdef DEBUG_PK 1127 buffer_dump(&b); 1128 #endif 1129 if (datafellows & SSH_BUG_PKSERVICE) { 1130 buffer_clear(&b); 1131 buffer_append(&b, session_id2, session_id2_len); 1132 skip = session_id2_len; 1133 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1134 buffer_put_cstring(&b, authctxt->server_user); 1135 buffer_put_cstring(&b, authctxt->service); 1136 buffer_put_cstring(&b, authctxt->method->name); 1137 buffer_put_char(&b, have_sig); 1138 if (!(datafellows & SSH_BUG_PKAUTH)) 1139 buffer_put_cstring(&b, key_ssh_name(id->key)); 1140 buffer_put_string(&b, blob, bloblen); 1141 } 1142 free(blob); 1143 1144 /* append signature */ 1145 buffer_put_string(&b, signature, slen); 1146 free(signature); 1147 1148 /* skip session id and packet type */ 1149 if (buffer_len(&b) < skip + 1) 1150 fatal("userauth_pubkey: internal error"); 1151 buffer_consume(&b, skip + 1); 1152 1153 /* put remaining data from buffer into packet */ 1154 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1155 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1156 buffer_free(&b); 1157 packet_send(); 1158 1159 return 1; 1160 } 1161 1162 static int 1163 send_pubkey_test(Authctxt *authctxt, Identity *id) 1164 { 1165 u_char *blob; 1166 u_int bloblen, have_sig = 0; 1167 1168 debug3("send_pubkey_test"); 1169 1170 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1171 /* we cannot handle this key */ 1172 debug3("send_pubkey_test: cannot handle key"); 1173 return 0; 1174 } 1175 /* register callback for USERAUTH_PK_OK message */ 1176 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1177 1178 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1179 packet_put_cstring(authctxt->server_user); 1180 packet_put_cstring(authctxt->service); 1181 packet_put_cstring(authctxt->method->name); 1182 packet_put_char(have_sig); 1183 if (!(datafellows & SSH_BUG_PKAUTH)) 1184 packet_put_cstring(identity_sign_encode(id)); 1185 packet_put_string(blob, bloblen); 1186 free(blob); 1187 packet_send(); 1188 return 1; 1189 } 1190 1191 static Key * 1192 load_identity_file(Identity *id) 1193 { 1194 Key *private = NULL; 1195 char prompt[300], *passphrase, *comment; 1196 int r, perm_ok = 0, quit = 0, i; 1197 struct stat st; 1198 1199 if (stat(id->filename, &st) < 0) { 1200 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1201 id->filename, strerror(errno)); 1202 return NULL; 1203 } 1204 snprintf(prompt, sizeof prompt, 1205 "Enter passphrase for key '%.100s': ", id->filename); 1206 for (i = 0; i <= options.number_of_password_prompts; i++) { 1207 if (i == 0) 1208 passphrase = ""; 1209 else { 1210 passphrase = read_passphrase(prompt, 0); 1211 if (*passphrase == '\0') { 1212 debug2("no passphrase given, try next key"); 1213 free(passphrase); 1214 break; 1215 } 1216 } 1217 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1218 passphrase, &private, &comment, &perm_ok))) { 1219 case 0: 1220 break; 1221 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1222 if (options.batch_mode) { 1223 quit = 1; 1224 break; 1225 } 1226 if (i != 0) 1227 debug2("bad passphrase given, try again..."); 1228 break; 1229 case SSH_ERR_SYSTEM_ERROR: 1230 if (errno == ENOENT) { 1231 debug2("Load key \"%s\": %s", 1232 id->filename, ssh_err(r)); 1233 quit = 1; 1234 break; 1235 } 1236 /* FALLTHROUGH */ 1237 default: 1238 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1239 quit = 1; 1240 break; 1241 } 1242 if (!quit && private != NULL && id->agent_fd == -1 && 1243 !(id->key && id->isprivate)) 1244 maybe_add_key_to_agent(id->filename, private, comment, 1245 passphrase); 1246 if (i > 0) { 1247 explicit_bzero(passphrase, strlen(passphrase)); 1248 free(passphrase); 1249 } 1250 free(comment); 1251 if (private != NULL || quit) 1252 break; 1253 } 1254 return private; 1255 } 1256 1257 /* 1258 * try keys in the following order: 1259 * 1. certificates listed in the config file 1260 * 2. other input certificates 1261 * 3. agent keys that are found in the config file 1262 * 4. other agent keys 1263 * 5. keys that are only listed in the config file 1264 */ 1265 static void 1266 pubkey_prepare(Authctxt *authctxt) 1267 { 1268 struct identity *id, *id2, *tmp; 1269 struct idlist agent, files, *preferred; 1270 struct sshkey *key; 1271 int agent_fd = -1, i, r, found; 1272 size_t j; 1273 struct ssh_identitylist *idlist; 1274 1275 TAILQ_INIT(&agent); /* keys from the agent */ 1276 TAILQ_INIT(&files); /* keys from the config file */ 1277 preferred = &authctxt->keys; 1278 TAILQ_INIT(preferred); /* preferred order of keys */ 1279 1280 /* list of keys stored in the filesystem and PKCS#11 */ 1281 for (i = 0; i < options.num_identity_files; i++) { 1282 key = options.identity_keys[i]; 1283 if (key && key->type == KEY_RSA1) 1284 continue; 1285 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1286 continue; 1287 options.identity_keys[i] = NULL; 1288 id = xcalloc(1, sizeof(*id)); 1289 id->agent_fd = -1; 1290 id->key = key; 1291 id->filename = xstrdup(options.identity_files[i]); 1292 id->userprovided = options.identity_file_userprovided[i]; 1293 TAILQ_INSERT_TAIL(&files, id, next); 1294 } 1295 /* list of certificates specified by user */ 1296 for (i = 0; i < options.num_certificate_files; i++) { 1297 key = options.certificates[i]; 1298 if (!key_is_cert(key) || key->cert == NULL || 1299 key->cert->type != SSH2_CERT_TYPE_USER) 1300 continue; 1301 id = xcalloc(1, sizeof(*id)); 1302 id->agent_fd = -1; 1303 id->key = key; 1304 id->filename = xstrdup(options.certificate_files[i]); 1305 id->userprovided = options.certificate_file_userprovided[i]; 1306 TAILQ_INSERT_TAIL(preferred, id, next); 1307 } 1308 /* list of keys supported by the agent */ 1309 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1310 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1311 debug("%s: ssh_get_authentication_socket: %s", 1312 __func__, ssh_err(r)); 1313 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1314 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1315 debug("%s: ssh_fetch_identitylist: %s", 1316 __func__, ssh_err(r)); 1317 close(agent_fd); 1318 } else { 1319 for (j = 0; j < idlist->nkeys; j++) { 1320 found = 0; 1321 TAILQ_FOREACH(id, &files, next) { 1322 /* 1323 * agent keys from the config file are 1324 * preferred 1325 */ 1326 if (sshkey_equal(idlist->keys[j], id->key)) { 1327 TAILQ_REMOVE(&files, id, next); 1328 TAILQ_INSERT_TAIL(preferred, id, next); 1329 id->agent_fd = agent_fd; 1330 found = 1; 1331 break; 1332 } 1333 } 1334 if (!found && !options.identities_only) { 1335 id = xcalloc(1, sizeof(*id)); 1336 /* XXX "steals" key/comment from idlist */ 1337 id->key = idlist->keys[j]; 1338 id->filename = idlist->comments[j]; 1339 idlist->keys[j] = NULL; 1340 idlist->comments[j] = NULL; 1341 id->agent_fd = agent_fd; 1342 TAILQ_INSERT_TAIL(&agent, id, next); 1343 } 1344 } 1345 ssh_free_identitylist(idlist); 1346 /* append remaining agent keys */ 1347 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1348 TAILQ_REMOVE(&agent, id, next); 1349 TAILQ_INSERT_TAIL(preferred, id, next); 1350 } 1351 authctxt->agent_fd = agent_fd; 1352 } 1353 /* Prefer PKCS11 keys that are explicitly listed */ 1354 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1355 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1356 continue; 1357 found = 0; 1358 TAILQ_FOREACH(id2, &files, next) { 1359 if (id2->key == NULL || 1360 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1361 continue; 1362 if (sshkey_equal(id->key, id2->key)) { 1363 TAILQ_REMOVE(&files, id, next); 1364 TAILQ_INSERT_TAIL(preferred, id, next); 1365 found = 1; 1366 break; 1367 } 1368 } 1369 /* If IdentitiesOnly set and key not found then don't use it */ 1370 if (!found && options.identities_only) { 1371 TAILQ_REMOVE(&files, id, next); 1372 explicit_bzero(id, sizeof(*id)); 1373 free(id); 1374 } 1375 } 1376 /* append remaining keys from the config file */ 1377 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1378 TAILQ_REMOVE(&files, id, next); 1379 TAILQ_INSERT_TAIL(preferred, id, next); 1380 } 1381 /* finally, filter by PubkeyAcceptedKeyTypes */ 1382 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1383 if (id->key != NULL && 1384 match_pattern_list(sshkey_ssh_name(id->key), 1385 options.pubkey_key_types, 0) != 1) { 1386 debug("Skipping %s key %s - " 1387 "not in PubkeyAcceptedKeyTypes", 1388 sshkey_ssh_name(id->key), id->filename); 1389 TAILQ_REMOVE(preferred, id, next); 1390 sshkey_free(id->key); 1391 free(id->filename); 1392 memset(id, 0, sizeof(*id)); 1393 continue; 1394 } 1395 debug2("key: %s (%p)%s%s", id->filename, id->key, 1396 id->userprovided ? ", explicit" : "", 1397 id->agent_fd != -1 ? ", agent" : ""); 1398 } 1399 } 1400 1401 static void 1402 pubkey_cleanup(Authctxt *authctxt) 1403 { 1404 Identity *id; 1405 1406 if (authctxt->agent_fd != -1) 1407 ssh_close_authentication_socket(authctxt->agent_fd); 1408 for (id = TAILQ_FIRST(&authctxt->keys); id; 1409 id = TAILQ_FIRST(&authctxt->keys)) { 1410 TAILQ_REMOVE(&authctxt->keys, id, next); 1411 sshkey_free(id->key); 1412 free(id->filename); 1413 free(id); 1414 } 1415 } 1416 1417 static void 1418 pubkey_reset(Authctxt *authctxt) 1419 { 1420 Identity *id; 1421 1422 TAILQ_FOREACH(id, &authctxt->keys, next) 1423 id->tried = 0; 1424 } 1425 1426 static int 1427 try_identity(Identity *id) 1428 { 1429 if (!id->key) 1430 return (0); 1431 if (key_type_plain(id->key->type) == KEY_RSA && 1432 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1433 debug("Skipped %s key %s for RSA/MD5 server", 1434 key_type(id->key), id->filename); 1435 return (0); 1436 } 1437 return (id->key->type != KEY_RSA1); 1438 } 1439 1440 int 1441 userauth_pubkey(Authctxt *authctxt) 1442 { 1443 Identity *id; 1444 int sent = 0; 1445 1446 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1447 if (id->tried++) 1448 return (0); 1449 /* move key to the end of the queue */ 1450 TAILQ_REMOVE(&authctxt->keys, id, next); 1451 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1452 /* 1453 * send a test message if we have the public key. for 1454 * encrypted keys we cannot do this and have to load the 1455 * private key instead 1456 */ 1457 if (id->key != NULL) { 1458 if (try_identity(id)) { 1459 debug("Offering %s public key: %s", 1460 key_type(id->key), id->filename); 1461 sent = send_pubkey_test(authctxt, id); 1462 } 1463 } else { 1464 debug("Trying private key: %s", id->filename); 1465 id->key = load_identity_file(id); 1466 if (id->key != NULL) { 1467 if (try_identity(id)) { 1468 id->isprivate = 1; 1469 sent = sign_and_send_pubkey( 1470 authctxt, id); 1471 } 1472 key_free(id->key); 1473 id->key = NULL; 1474 id->isprivate = 0; 1475 } 1476 } 1477 if (sent) 1478 return (sent); 1479 } 1480 return (0); 1481 } 1482 1483 /* 1484 * Send userauth request message specifying keyboard-interactive method. 1485 */ 1486 int 1487 userauth_kbdint(Authctxt *authctxt) 1488 { 1489 static int attempt = 0; 1490 1491 if (attempt++ >= options.number_of_password_prompts) 1492 return 0; 1493 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1494 if (attempt > 1 && !authctxt->info_req_seen) { 1495 debug3("userauth_kbdint: disable: no info_req_seen"); 1496 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1497 return 0; 1498 } 1499 1500 debug2("userauth_kbdint"); 1501 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1502 packet_put_cstring(authctxt->server_user); 1503 packet_put_cstring(authctxt->service); 1504 packet_put_cstring(authctxt->method->name); 1505 packet_put_cstring(""); /* lang */ 1506 packet_put_cstring(options.kbd_interactive_devices ? 1507 options.kbd_interactive_devices : ""); 1508 packet_send(); 1509 1510 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1511 return 1; 1512 } 1513 1514 /* 1515 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1516 */ 1517 int 1518 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1519 { 1520 Authctxt *authctxt = ctxt; 1521 char *name, *inst, *lang, *prompt, *response; 1522 u_int num_prompts, i; 1523 int echo = 0; 1524 1525 debug2("input_userauth_info_req"); 1526 1527 if (authctxt == NULL) 1528 fatal("input_userauth_info_req: no authentication context"); 1529 1530 authctxt->info_req_seen = 1; 1531 1532 name = packet_get_string(NULL); 1533 inst = packet_get_string(NULL); 1534 lang = packet_get_string(NULL); 1535 if (strlen(name) > 0) 1536 logit("%s", name); 1537 if (strlen(inst) > 0) 1538 logit("%s", inst); 1539 free(name); 1540 free(inst); 1541 free(lang); 1542 1543 num_prompts = packet_get_int(); 1544 /* 1545 * Begin to build info response packet based on prompts requested. 1546 * We commit to providing the correct number of responses, so if 1547 * further on we run into a problem that prevents this, we have to 1548 * be sure and clean this up and send a correct error response. 1549 */ 1550 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1551 packet_put_int(num_prompts); 1552 1553 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1554 for (i = 0; i < num_prompts; i++) { 1555 prompt = packet_get_string(NULL); 1556 echo = packet_get_char(); 1557 1558 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1559 1560 packet_put_cstring(response); 1561 explicit_bzero(response, strlen(response)); 1562 free(response); 1563 free(prompt); 1564 } 1565 packet_check_eom(); /* done with parsing incoming message. */ 1566 1567 packet_add_padding(64); 1568 packet_send(); 1569 return 0; 1570 } 1571 1572 static int 1573 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1574 const u_char *data, size_t datalen) 1575 { 1576 struct sshbuf *b; 1577 struct stat st; 1578 pid_t pid; 1579 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1580 u_char rversion = 0, version = 2; 1581 void (*osigchld)(int); 1582 1583 *sigp = NULL; 1584 *lenp = 0; 1585 1586 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1587 error("%s: not installed: %s", __func__, strerror(errno)); 1588 return -1; 1589 } 1590 if (fflush(stdout) != 0) { 1591 error("%s: fflush: %s", __func__, strerror(errno)); 1592 return -1; 1593 } 1594 if (pipe(to) < 0) { 1595 error("%s: pipe: %s", __func__, strerror(errno)); 1596 return -1; 1597 } 1598 if (pipe(from) < 0) { 1599 error("%s: pipe: %s", __func__, strerror(errno)); 1600 return -1; 1601 } 1602 if ((pid = fork()) < 0) { 1603 error("%s: fork: %s", __func__, strerror(errno)); 1604 return -1; 1605 } 1606 osigchld = signal(SIGCHLD, SIG_DFL); 1607 if (pid == 0) { 1608 /* keep the socket on exec */ 1609 fcntl(sock, F_SETFD, 0); 1610 permanently_drop_suid(getuid()); 1611 close(from[0]); 1612 if (dup2(from[1], STDOUT_FILENO) < 0) 1613 fatal("%s: dup2: %s", __func__, strerror(errno)); 1614 close(to[1]); 1615 if (dup2(to[0], STDIN_FILENO) < 0) 1616 fatal("%s: dup2: %s", __func__, strerror(errno)); 1617 close(from[1]); 1618 close(to[0]); 1619 /* Close everything but stdio and the socket */ 1620 for (i = STDERR_FILENO + 1; i < sock; i++) 1621 close(i); 1622 closefrom(sock + 1); 1623 debug3("%s: [child] pid=%ld, exec %s", 1624 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1625 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1626 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1627 strerror(errno)); 1628 } 1629 close(from[1]); 1630 close(to[0]); 1631 1632 if ((b = sshbuf_new()) == NULL) 1633 fatal("%s: sshbuf_new failed", __func__); 1634 /* send # of sock, data to be signed */ 1635 if ((r = sshbuf_put_u32(b, sock) != 0) || 1636 (r = sshbuf_put_string(b, data, datalen)) != 0) 1637 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1638 if (ssh_msg_send(to[1], version, b) == -1) 1639 fatal("%s: couldn't send request", __func__); 1640 sshbuf_reset(b); 1641 r = ssh_msg_recv(from[0], b); 1642 close(from[0]); 1643 close(to[1]); 1644 if (r < 0) { 1645 error("%s: no reply", __func__); 1646 goto fail; 1647 } 1648 1649 errno = 0; 1650 while (waitpid(pid, &status, 0) < 0) { 1651 if (errno != EINTR) { 1652 error("%s: waitpid %ld: %s", 1653 __func__, (long)pid, strerror(errno)); 1654 goto fail; 1655 } 1656 } 1657 if (!WIFEXITED(status)) { 1658 error("%s: exited abnormally", __func__); 1659 goto fail; 1660 } 1661 if (WEXITSTATUS(status) != 0) { 1662 error("%s: exited with status %d", 1663 __func__, WEXITSTATUS(status)); 1664 goto fail; 1665 } 1666 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1667 error("%s: buffer error: %s", __func__, ssh_err(r)); 1668 goto fail; 1669 } 1670 if (rversion != version) { 1671 error("%s: bad version", __func__); 1672 goto fail; 1673 } 1674 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1675 error("%s: buffer error: %s", __func__, ssh_err(r)); 1676 fail: 1677 signal(SIGCHLD, osigchld); 1678 sshbuf_free(b); 1679 return -1; 1680 } 1681 signal(SIGCHLD, osigchld); 1682 sshbuf_free(b); 1683 1684 return 0; 1685 } 1686 1687 int 1688 userauth_hostbased(Authctxt *authctxt) 1689 { 1690 struct ssh *ssh = active_state; 1691 struct sshkey *private = NULL; 1692 struct sshbuf *b = NULL; 1693 const char *service; 1694 u_char *sig = NULL, *keyblob = NULL; 1695 char *fp = NULL, *chost = NULL, *lname = NULL; 1696 size_t siglen = 0, keylen = 0; 1697 int i, r, success = 0; 1698 1699 if (authctxt->ktypes == NULL) { 1700 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1701 authctxt->ktypes = authctxt->oktypes; 1702 } 1703 1704 /* 1705 * Work through each listed type pattern in HostbasedKeyTypes, 1706 * trying each hostkey that matches the type in turn. 1707 */ 1708 for (;;) { 1709 if (authctxt->active_ktype == NULL) 1710 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1711 if (authctxt->active_ktype == NULL || 1712 *authctxt->active_ktype == '\0') 1713 break; 1714 debug3("%s: trying key type %s", __func__, 1715 authctxt->active_ktype); 1716 1717 /* check for a useful key */ 1718 private = NULL; 1719 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1720 if (authctxt->sensitive->keys[i] == NULL || 1721 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1722 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1723 continue; 1724 if (match_pattern_list( 1725 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1726 authctxt->active_ktype, 0) != 1) 1727 continue; 1728 /* we take and free the key */ 1729 private = authctxt->sensitive->keys[i]; 1730 authctxt->sensitive->keys[i] = NULL; 1731 break; 1732 } 1733 /* Found one */ 1734 if (private != NULL) 1735 break; 1736 /* No more keys of this type; advance */ 1737 authctxt->active_ktype = NULL; 1738 } 1739 if (private == NULL) { 1740 free(authctxt->oktypes); 1741 authctxt->oktypes = authctxt->ktypes = NULL; 1742 authctxt->active_ktype = NULL; 1743 debug("No more client hostkeys for hostbased authentication."); 1744 goto out; 1745 } 1746 1747 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1748 SSH_FP_DEFAULT)) == NULL) { 1749 error("%s: sshkey_fingerprint failed", __func__); 1750 goto out; 1751 } 1752 debug("%s: trying hostkey %s %s", 1753 __func__, sshkey_ssh_name(private), fp); 1754 1755 /* figure out a name for the client host */ 1756 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1757 error("%s: cannot get local ipaddr/name", __func__); 1758 goto out; 1759 } 1760 1761 /* XXX sshbuf_put_stringf? */ 1762 xasprintf(&chost, "%s.", lname); 1763 debug2("%s: chost %s", __func__, chost); 1764 1765 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1766 authctxt->service; 1767 1768 /* construct data */ 1769 if ((b = sshbuf_new()) == NULL) { 1770 error("%s: sshbuf_new failed", __func__); 1771 goto out; 1772 } 1773 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1774 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1775 goto out; 1776 } 1777 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1778 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1779 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1780 (r = sshbuf_put_cstring(b, service)) != 0 || 1781 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1782 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1783 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1784 (r = sshbuf_put_cstring(b, chost)) != 0 || 1785 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1786 error("%s: buffer error: %s", __func__, ssh_err(r)); 1787 goto out; 1788 } 1789 1790 #ifdef DEBUG_PK 1791 sshbuf_dump(b, stderr); 1792 #endif 1793 if (authctxt->sensitive->external_keysign) 1794 r = ssh_keysign(private, &sig, &siglen, 1795 sshbuf_ptr(b), sshbuf_len(b)); 1796 else if ((r = sshkey_sign(private, &sig, &siglen, 1797 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1798 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1799 if (r != 0) { 1800 error("sign using hostkey %s %s failed", 1801 sshkey_ssh_name(private), fp); 1802 goto out; 1803 } 1804 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1805 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1806 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1807 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1808 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1809 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1810 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1811 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1812 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1813 (r = sshpkt_send(ssh)) != 0) { 1814 error("%s: packet error: %s", __func__, ssh_err(r)); 1815 goto out; 1816 } 1817 success = 1; 1818 1819 out: 1820 if (sig != NULL) { 1821 explicit_bzero(sig, siglen); 1822 free(sig); 1823 } 1824 free(keyblob); 1825 free(lname); 1826 free(fp); 1827 free(chost); 1828 sshkey_free(private); 1829 sshbuf_free(b); 1830 1831 return success; 1832 } 1833 1834 /* find auth method */ 1835 1836 /* 1837 * given auth method name, if configurable options permit this method fill 1838 * in auth_ident field and return true, otherwise return false. 1839 */ 1840 static int 1841 authmethod_is_enabled(Authmethod *method) 1842 { 1843 if (method == NULL) 1844 return 0; 1845 /* return false if options indicate this method is disabled */ 1846 if (method->enabled == NULL || *method->enabled == 0) 1847 return 0; 1848 /* return false if batch mode is enabled but method needs interactive mode */ 1849 if (method->batch_flag != NULL && *method->batch_flag != 0) 1850 return 0; 1851 return 1; 1852 } 1853 1854 static Authmethod * 1855 authmethod_lookup(const char *name) 1856 { 1857 Authmethod *method = NULL; 1858 if (name != NULL) 1859 for (method = authmethods; method->name != NULL; method++) 1860 if (strcmp(name, method->name) == 0) 1861 return method; 1862 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1863 return NULL; 1864 } 1865 1866 /* XXX internal state */ 1867 static Authmethod *current = NULL; 1868 static char *supported = NULL; 1869 static char *preferred = NULL; 1870 1871 /* 1872 * Given the authentication method list sent by the server, return the 1873 * next method we should try. If the server initially sends a nil list, 1874 * use a built-in default list. 1875 */ 1876 static Authmethod * 1877 authmethod_get(char *authlist) 1878 { 1879 char *name = NULL; 1880 u_int next; 1881 1882 /* Use a suitable default if we're passed a nil list. */ 1883 if (authlist == NULL || strlen(authlist) == 0) 1884 authlist = options.preferred_authentications; 1885 1886 if (supported == NULL || strcmp(authlist, supported) != 0) { 1887 debug3("start over, passed a different list %s", authlist); 1888 free(supported); 1889 supported = xstrdup(authlist); 1890 preferred = options.preferred_authentications; 1891 debug3("preferred %s", preferred); 1892 current = NULL; 1893 } else if (current != NULL && authmethod_is_enabled(current)) 1894 return current; 1895 1896 for (;;) { 1897 if ((name = match_list(preferred, supported, &next)) == NULL) { 1898 debug("No more authentication methods to try."); 1899 current = NULL; 1900 return NULL; 1901 } 1902 preferred += next; 1903 debug3("authmethod_lookup %s", name); 1904 debug3("remaining preferred: %s", preferred); 1905 if ((current = authmethod_lookup(name)) != NULL && 1906 authmethod_is_enabled(current)) { 1907 debug3("authmethod_is_enabled %s", name); 1908 debug("Next authentication method: %s", name); 1909 free(name); 1910 return current; 1911 } 1912 free(name); 1913 } 1914 } 1915 1916 static char * 1917 authmethods_get(void) 1918 { 1919 Authmethod *method = NULL; 1920 Buffer b; 1921 char *list; 1922 1923 buffer_init(&b); 1924 for (method = authmethods; method->name != NULL; method++) { 1925 if (authmethod_is_enabled(method)) { 1926 if (buffer_len(&b) > 0) 1927 buffer_append(&b, ",", 1); 1928 buffer_append(&b, method->name, strlen(method->name)); 1929 } 1930 } 1931 if ((list = sshbuf_dup_string(&b)) == NULL) 1932 fatal("%s: sshbuf_dup_string failed", __func__); 1933 buffer_free(&b); 1934 return list; 1935 } 1936 1937