1 /* $OpenBSD: sshconnect2.c,v 1.255 2017/03/11 23:40:26 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 (at) openssh.com,zlib,none" : "none,zlib (at) 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(options.rekey_limit, 197 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; 938 939 debug2("input_userauth_passwd_changereq"); 940 941 if (authctxt == NULL) 942 fatal("input_userauth_passwd_changereq: " 943 "no authentication context"); 944 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 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 key_sign_encode(const struct sshkey *key) 1000 { 1001 struct ssh *ssh = active_state; 1002 1003 if (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(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 1021 /* the agent supports this key */ 1022 if (id->key != NULL && id->agent_fd != -1) 1023 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1024 data, datalen, key_sign_encode(id->key), compat); 1025 1026 /* 1027 * we have already loaded the private key or 1028 * the private key is stored in external hardware 1029 */ 1030 if (id->key != NULL && 1031 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) 1032 return (sshkey_sign(id->key, sigp, lenp, data, datalen, 1033 key_sign_encode(id->key), compat)); 1034 1035 /* load the private key from the file */ 1036 if ((prv = load_identity_file(id)) == NULL) 1037 return SSH_ERR_KEY_NOT_FOUND; 1038 ret = sshkey_sign(prv, sigp, lenp, data, datalen, 1039 key_sign_encode(prv), compat); 1040 sshkey_free(prv); 1041 return (ret); 1042 } 1043 1044 static int 1045 id_filename_matches(Identity *id, Identity *private_id) 1046 { 1047 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1048 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1049 size_t i, slen; 1050 1051 if (strcmp(id->filename, private_id->filename) == 0) 1052 return 1; 1053 for (i = 0; suffixes[i]; i++) { 1054 slen = strlen(suffixes[i]); 1055 if (len > slen && plen == len - slen && 1056 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1057 memcmp(id->filename, private_id->filename, plen) == 0) 1058 return 1; 1059 } 1060 return 0; 1061 } 1062 1063 static int 1064 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1065 { 1066 Buffer b; 1067 Identity *private_id; 1068 u_char *blob, *signature; 1069 size_t slen; 1070 u_int bloblen, skip = 0; 1071 int matched, ret = -1, have_sig = 1; 1072 char *fp; 1073 1074 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1075 SSH_FP_DEFAULT)) == NULL) 1076 return 0; 1077 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1078 free(fp); 1079 1080 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1081 /* we cannot handle this key */ 1082 debug3("sign_and_send_pubkey: cannot handle key"); 1083 return 0; 1084 } 1085 /* data to be signed */ 1086 buffer_init(&b); 1087 if (datafellows & SSH_OLD_SESSIONID) { 1088 buffer_append(&b, session_id2, session_id2_len); 1089 skip = session_id2_len; 1090 } else { 1091 buffer_put_string(&b, session_id2, session_id2_len); 1092 skip = buffer_len(&b); 1093 } 1094 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1095 buffer_put_cstring(&b, authctxt->server_user); 1096 buffer_put_cstring(&b, 1097 datafellows & SSH_BUG_PKSERVICE ? 1098 "ssh-userauth" : 1099 authctxt->service); 1100 if (datafellows & SSH_BUG_PKAUTH) { 1101 buffer_put_char(&b, have_sig); 1102 } else { 1103 buffer_put_cstring(&b, authctxt->method->name); 1104 buffer_put_char(&b, have_sig); 1105 buffer_put_cstring(&b, key_sign_encode(id->key)); 1106 } 1107 buffer_put_string(&b, blob, bloblen); 1108 1109 /* 1110 * If the key is an certificate, try to find a matching private key 1111 * and use it to complete the signature. 1112 * If no such private key exists, fall back to trying the certificate 1113 * key itself in case it has a private half already loaded. 1114 */ 1115 if (key_is_cert(id->key)) { 1116 matched = 0; 1117 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1118 if (sshkey_equal_public(id->key, private_id->key) && 1119 id->key->type != private_id->key->type) { 1120 id = private_id; 1121 matched = 1; 1122 break; 1123 } 1124 } 1125 /* 1126 * Exact key matches are preferred, but also allow 1127 * filename matches for non-PKCS#11/agent keys that 1128 * didn't load public keys. This supports the case 1129 * of keeping just a private key file and public 1130 * certificate on disk. 1131 */ 1132 if (!matched && !id->isprivate && id->agent_fd == -1 && 1133 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1134 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1135 if (private_id->key == NULL && 1136 id_filename_matches(id, private_id)) { 1137 id = private_id; 1138 matched = 1; 1139 break; 1140 } 1141 } 1142 } 1143 if (matched) { 1144 debug2("%s: using private key \"%s\"%s for " 1145 "certificate", __func__, id->filename, 1146 id->agent_fd != -1 ? " from agent" : ""); 1147 } else { 1148 debug("%s: no separate private key for certificate " 1149 "\"%s\"", __func__, id->filename); 1150 } 1151 } 1152 1153 /* generate signature */ 1154 ret = identity_sign(id, &signature, &slen, 1155 buffer_ptr(&b), buffer_len(&b), datafellows); 1156 if (ret != 0) { 1157 if (ret != SSH_ERR_KEY_NOT_FOUND) 1158 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1159 free(blob); 1160 buffer_free(&b); 1161 return 0; 1162 } 1163 #ifdef DEBUG_PK 1164 buffer_dump(&b); 1165 #endif 1166 if (datafellows & SSH_BUG_PKSERVICE) { 1167 buffer_clear(&b); 1168 buffer_append(&b, session_id2, session_id2_len); 1169 skip = session_id2_len; 1170 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1171 buffer_put_cstring(&b, authctxt->server_user); 1172 buffer_put_cstring(&b, authctxt->service); 1173 buffer_put_cstring(&b, authctxt->method->name); 1174 buffer_put_char(&b, have_sig); 1175 if (!(datafellows & SSH_BUG_PKAUTH)) 1176 buffer_put_cstring(&b, key_ssh_name(id->key)); 1177 buffer_put_string(&b, blob, bloblen); 1178 } 1179 free(blob); 1180 1181 /* append signature */ 1182 buffer_put_string(&b, signature, slen); 1183 free(signature); 1184 1185 /* skip session id and packet type */ 1186 if (buffer_len(&b) < skip + 1) 1187 fatal("userauth_pubkey: internal error"); 1188 buffer_consume(&b, skip + 1); 1189 1190 /* put remaining data from buffer into packet */ 1191 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1192 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1193 buffer_free(&b); 1194 packet_send(); 1195 1196 return 1; 1197 } 1198 1199 static int 1200 send_pubkey_test(Authctxt *authctxt, Identity *id) 1201 { 1202 u_char *blob; 1203 u_int bloblen, have_sig = 0; 1204 1205 debug3("send_pubkey_test"); 1206 1207 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1208 /* we cannot handle this key */ 1209 debug3("send_pubkey_test: cannot handle key"); 1210 return 0; 1211 } 1212 /* register callback for USERAUTH_PK_OK message */ 1213 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1214 1215 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1216 packet_put_cstring(authctxt->server_user); 1217 packet_put_cstring(authctxt->service); 1218 packet_put_cstring(authctxt->method->name); 1219 packet_put_char(have_sig); 1220 if (!(datafellows & SSH_BUG_PKAUTH)) 1221 packet_put_cstring(key_sign_encode(id->key)); 1222 packet_put_string(blob, bloblen); 1223 free(blob); 1224 packet_send(); 1225 return 1; 1226 } 1227 1228 static Key * 1229 load_identity_file(Identity *id) 1230 { 1231 Key *private = NULL; 1232 char prompt[300], *passphrase, *comment; 1233 int r, perm_ok = 0, quit = 0, i; 1234 struct stat st; 1235 1236 if (stat(id->filename, &st) < 0) { 1237 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1238 id->filename, strerror(errno)); 1239 return NULL; 1240 } 1241 snprintf(prompt, sizeof prompt, 1242 "Enter passphrase for key '%.100s': ", id->filename); 1243 for (i = 0; i <= options.number_of_password_prompts; i++) { 1244 if (i == 0) 1245 passphrase = ""; 1246 else { 1247 passphrase = read_passphrase(prompt, 0); 1248 if (*passphrase == '\0') { 1249 debug2("no passphrase given, try next key"); 1250 free(passphrase); 1251 break; 1252 } 1253 } 1254 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1255 passphrase, &private, &comment, &perm_ok))) { 1256 case 0: 1257 break; 1258 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1259 if (options.batch_mode) { 1260 quit = 1; 1261 break; 1262 } 1263 if (i != 0) 1264 debug2("bad passphrase given, try again..."); 1265 break; 1266 case SSH_ERR_SYSTEM_ERROR: 1267 if (errno == ENOENT) { 1268 debug2("Load key \"%s\": %s", 1269 id->filename, ssh_err(r)); 1270 quit = 1; 1271 break; 1272 } 1273 /* FALLTHROUGH */ 1274 default: 1275 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1276 quit = 1; 1277 break; 1278 } 1279 if (!quit && private != NULL && id->agent_fd == -1 && 1280 !(id->key && id->isprivate)) 1281 maybe_add_key_to_agent(id->filename, private, comment, 1282 passphrase); 1283 if (i > 0) { 1284 explicit_bzero(passphrase, strlen(passphrase)); 1285 free(passphrase); 1286 } 1287 free(comment); 1288 if (private != NULL || quit) 1289 break; 1290 } 1291 return private; 1292 } 1293 1294 /* 1295 * try keys in the following order: 1296 * 1. certificates listed in the config file 1297 * 2. other input certificates 1298 * 3. agent keys that are found in the config file 1299 * 4. other agent keys 1300 * 5. keys that are only listed in the config file 1301 */ 1302 static void 1303 pubkey_prepare(Authctxt *authctxt) 1304 { 1305 struct identity *id, *id2, *tmp; 1306 struct idlist agent, files, *preferred; 1307 struct sshkey *key; 1308 int agent_fd = -1, i, r, found; 1309 size_t j; 1310 struct ssh_identitylist *idlist; 1311 1312 TAILQ_INIT(&agent); /* keys from the agent */ 1313 TAILQ_INIT(&files); /* keys from the config file */ 1314 preferred = &authctxt->keys; 1315 TAILQ_INIT(preferred); /* preferred order of keys */ 1316 1317 /* list of keys stored in the filesystem and PKCS#11 */ 1318 for (i = 0; i < options.num_identity_files; i++) { 1319 key = options.identity_keys[i]; 1320 if (key && key->type == KEY_RSA1) 1321 continue; 1322 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1323 continue; 1324 options.identity_keys[i] = NULL; 1325 id = xcalloc(1, sizeof(*id)); 1326 id->agent_fd = -1; 1327 id->key = key; 1328 id->filename = xstrdup(options.identity_files[i]); 1329 id->userprovided = options.identity_file_userprovided[i]; 1330 TAILQ_INSERT_TAIL(&files, id, next); 1331 } 1332 /* list of certificates specified by user */ 1333 for (i = 0; i < options.num_certificate_files; i++) { 1334 key = options.certificates[i]; 1335 if (!key_is_cert(key) || key->cert == NULL || 1336 key->cert->type != SSH2_CERT_TYPE_USER) 1337 continue; 1338 id = xcalloc(1, sizeof(*id)); 1339 id->agent_fd = -1; 1340 id->key = key; 1341 id->filename = xstrdup(options.certificate_files[i]); 1342 id->userprovided = options.certificate_file_userprovided[i]; 1343 TAILQ_INSERT_TAIL(preferred, id, next); 1344 } 1345 /* list of keys supported by the agent */ 1346 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1347 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1348 debug("%s: ssh_get_authentication_socket: %s", 1349 __func__, ssh_err(r)); 1350 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1351 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1352 debug("%s: ssh_fetch_identitylist: %s", 1353 __func__, ssh_err(r)); 1354 close(agent_fd); 1355 } else { 1356 for (j = 0; j < idlist->nkeys; j++) { 1357 found = 0; 1358 TAILQ_FOREACH(id, &files, next) { 1359 /* 1360 * agent keys from the config file are 1361 * preferred 1362 */ 1363 if (sshkey_equal(idlist->keys[j], id->key)) { 1364 TAILQ_REMOVE(&files, id, next); 1365 TAILQ_INSERT_TAIL(preferred, id, next); 1366 id->agent_fd = agent_fd; 1367 found = 1; 1368 break; 1369 } 1370 } 1371 if (!found && !options.identities_only) { 1372 id = xcalloc(1, sizeof(*id)); 1373 /* XXX "steals" key/comment from idlist */ 1374 id->key = idlist->keys[j]; 1375 id->filename = idlist->comments[j]; 1376 idlist->keys[j] = NULL; 1377 idlist->comments[j] = NULL; 1378 id->agent_fd = agent_fd; 1379 TAILQ_INSERT_TAIL(&agent, id, next); 1380 } 1381 } 1382 ssh_free_identitylist(idlist); 1383 /* append remaining agent keys */ 1384 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1385 TAILQ_REMOVE(&agent, id, next); 1386 TAILQ_INSERT_TAIL(preferred, id, next); 1387 } 1388 authctxt->agent_fd = agent_fd; 1389 } 1390 /* Prefer PKCS11 keys that are explicitly listed */ 1391 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1392 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1393 continue; 1394 found = 0; 1395 TAILQ_FOREACH(id2, &files, next) { 1396 if (id2->key == NULL || 1397 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1398 continue; 1399 if (sshkey_equal(id->key, id2->key)) { 1400 TAILQ_REMOVE(&files, id, next); 1401 TAILQ_INSERT_TAIL(preferred, id, next); 1402 found = 1; 1403 break; 1404 } 1405 } 1406 /* If IdentitiesOnly set and key not found then don't use it */ 1407 if (!found && options.identities_only) { 1408 TAILQ_REMOVE(&files, id, next); 1409 explicit_bzero(id, sizeof(*id)); 1410 free(id); 1411 } 1412 } 1413 /* append remaining keys from the config file */ 1414 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1415 TAILQ_REMOVE(&files, id, next); 1416 TAILQ_INSERT_TAIL(preferred, id, next); 1417 } 1418 /* finally, filter by PubkeyAcceptedKeyTypes */ 1419 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1420 if (id->key != NULL && 1421 match_pattern_list(sshkey_ssh_name(id->key), 1422 options.pubkey_key_types, 0) != 1) { 1423 debug("Skipping %s key %s - " 1424 "not in PubkeyAcceptedKeyTypes", 1425 sshkey_ssh_name(id->key), id->filename); 1426 TAILQ_REMOVE(preferred, id, next); 1427 sshkey_free(id->key); 1428 free(id->filename); 1429 memset(id, 0, sizeof(*id)); 1430 continue; 1431 } 1432 debug2("key: %s (%p)%s%s", id->filename, id->key, 1433 id->userprovided ? ", explicit" : "", 1434 id->agent_fd != -1 ? ", agent" : ""); 1435 } 1436 } 1437 1438 static void 1439 pubkey_cleanup(Authctxt *authctxt) 1440 { 1441 Identity *id; 1442 1443 if (authctxt->agent_fd != -1) 1444 ssh_close_authentication_socket(authctxt->agent_fd); 1445 for (id = TAILQ_FIRST(&authctxt->keys); id; 1446 id = TAILQ_FIRST(&authctxt->keys)) { 1447 TAILQ_REMOVE(&authctxt->keys, id, next); 1448 sshkey_free(id->key); 1449 free(id->filename); 1450 free(id); 1451 } 1452 } 1453 1454 static void 1455 pubkey_reset(Authctxt *authctxt) 1456 { 1457 Identity *id; 1458 1459 TAILQ_FOREACH(id, &authctxt->keys, next) 1460 id->tried = 0; 1461 } 1462 1463 static int 1464 try_identity(Identity *id) 1465 { 1466 if (!id->key) 1467 return (0); 1468 if (key_type_plain(id->key->type) == KEY_RSA && 1469 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1470 debug("Skipped %s key %s for RSA/MD5 server", 1471 key_type(id->key), id->filename); 1472 return (0); 1473 } 1474 return (id->key->type != KEY_RSA1); 1475 } 1476 1477 int 1478 userauth_pubkey(Authctxt *authctxt) 1479 { 1480 Identity *id; 1481 int sent = 0; 1482 1483 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1484 if (id->tried++) 1485 return (0); 1486 /* move key to the end of the queue */ 1487 TAILQ_REMOVE(&authctxt->keys, id, next); 1488 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1489 /* 1490 * send a test message if we have the public key. for 1491 * encrypted keys we cannot do this and have to load the 1492 * private key instead 1493 */ 1494 if (id->key != NULL) { 1495 if (try_identity(id)) { 1496 debug("Offering %s public key: %s", 1497 key_type(id->key), id->filename); 1498 sent = send_pubkey_test(authctxt, id); 1499 } 1500 } else { 1501 debug("Trying private key: %s", id->filename); 1502 id->key = load_identity_file(id); 1503 if (id->key != NULL) { 1504 if (try_identity(id)) { 1505 id->isprivate = 1; 1506 sent = sign_and_send_pubkey( 1507 authctxt, id); 1508 } 1509 key_free(id->key); 1510 id->key = NULL; 1511 id->isprivate = 0; 1512 } 1513 } 1514 if (sent) 1515 return (sent); 1516 } 1517 return (0); 1518 } 1519 1520 /* 1521 * Send userauth request message specifying keyboard-interactive method. 1522 */ 1523 int 1524 userauth_kbdint(Authctxt *authctxt) 1525 { 1526 static int attempt = 0; 1527 1528 if (attempt++ >= options.number_of_password_prompts) 1529 return 0; 1530 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1531 if (attempt > 1 && !authctxt->info_req_seen) { 1532 debug3("userauth_kbdint: disable: no info_req_seen"); 1533 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1534 return 0; 1535 } 1536 1537 debug2("userauth_kbdint"); 1538 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1539 packet_put_cstring(authctxt->server_user); 1540 packet_put_cstring(authctxt->service); 1541 packet_put_cstring(authctxt->method->name); 1542 packet_put_cstring(""); /* lang */ 1543 packet_put_cstring(options.kbd_interactive_devices ? 1544 options.kbd_interactive_devices : ""); 1545 packet_send(); 1546 1547 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1548 return 1; 1549 } 1550 1551 /* 1552 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1553 */ 1554 int 1555 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1556 { 1557 Authctxt *authctxt = ctxt; 1558 char *name, *inst, *lang, *prompt, *response; 1559 u_int num_prompts, i; 1560 int echo = 0; 1561 1562 debug2("input_userauth_info_req"); 1563 1564 if (authctxt == NULL) 1565 fatal("input_userauth_info_req: no authentication context"); 1566 1567 authctxt->info_req_seen = 1; 1568 1569 name = packet_get_string(NULL); 1570 inst = packet_get_string(NULL); 1571 lang = packet_get_string(NULL); 1572 if (strlen(name) > 0) 1573 logit("%s", name); 1574 if (strlen(inst) > 0) 1575 logit("%s", inst); 1576 free(name); 1577 free(inst); 1578 free(lang); 1579 1580 num_prompts = packet_get_int(); 1581 /* 1582 * Begin to build info response packet based on prompts requested. 1583 * We commit to providing the correct number of responses, so if 1584 * further on we run into a problem that prevents this, we have to 1585 * be sure and clean this up and send a correct error response. 1586 */ 1587 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1588 packet_put_int(num_prompts); 1589 1590 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1591 for (i = 0; i < num_prompts; i++) { 1592 prompt = packet_get_string(NULL); 1593 echo = packet_get_char(); 1594 1595 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1596 1597 packet_put_cstring(response); 1598 explicit_bzero(response, strlen(response)); 1599 free(response); 1600 free(prompt); 1601 } 1602 packet_check_eom(); /* done with parsing incoming message. */ 1603 1604 packet_add_padding(64); 1605 packet_send(); 1606 return 0; 1607 } 1608 1609 static int 1610 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1611 const u_char *data, size_t datalen) 1612 { 1613 struct sshbuf *b; 1614 struct stat st; 1615 pid_t pid; 1616 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1617 u_char rversion = 0, version = 2; 1618 void (*osigchld)(int); 1619 1620 *sigp = NULL; 1621 *lenp = 0; 1622 1623 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1624 error("%s: not installed: %s", __func__, strerror(errno)); 1625 return -1; 1626 } 1627 if (fflush(stdout) != 0) { 1628 error("%s: fflush: %s", __func__, strerror(errno)); 1629 return -1; 1630 } 1631 if (pipe(to) < 0) { 1632 error("%s: pipe: %s", __func__, strerror(errno)); 1633 return -1; 1634 } 1635 if (pipe(from) < 0) { 1636 error("%s: pipe: %s", __func__, strerror(errno)); 1637 return -1; 1638 } 1639 if ((pid = fork()) < 0) { 1640 error("%s: fork: %s", __func__, strerror(errno)); 1641 return -1; 1642 } 1643 osigchld = signal(SIGCHLD, SIG_DFL); 1644 if (pid == 0) { 1645 /* keep the socket on exec */ 1646 fcntl(sock, F_SETFD, 0); 1647 permanently_drop_suid(getuid()); 1648 close(from[0]); 1649 if (dup2(from[1], STDOUT_FILENO) < 0) 1650 fatal("%s: dup2: %s", __func__, strerror(errno)); 1651 close(to[1]); 1652 if (dup2(to[0], STDIN_FILENO) < 0) 1653 fatal("%s: dup2: %s", __func__, strerror(errno)); 1654 close(from[1]); 1655 close(to[0]); 1656 /* Close everything but stdio and the socket */ 1657 for (i = STDERR_FILENO + 1; i < sock; i++) 1658 close(i); 1659 closefrom(sock + 1); 1660 debug3("%s: [child] pid=%ld, exec %s", 1661 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1662 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1663 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1664 strerror(errno)); 1665 } 1666 close(from[1]); 1667 close(to[0]); 1668 1669 if ((b = sshbuf_new()) == NULL) 1670 fatal("%s: sshbuf_new failed", __func__); 1671 /* send # of sock, data to be signed */ 1672 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1673 (r = sshbuf_put_string(b, data, datalen)) != 0) 1674 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1675 if (ssh_msg_send(to[1], version, b) == -1) 1676 fatal("%s: couldn't send request", __func__); 1677 sshbuf_reset(b); 1678 r = ssh_msg_recv(from[0], b); 1679 close(from[0]); 1680 close(to[1]); 1681 if (r < 0) { 1682 error("%s: no reply", __func__); 1683 goto fail; 1684 } 1685 1686 errno = 0; 1687 while (waitpid(pid, &status, 0) < 0) { 1688 if (errno != EINTR) { 1689 error("%s: waitpid %ld: %s", 1690 __func__, (long)pid, strerror(errno)); 1691 goto fail; 1692 } 1693 } 1694 if (!WIFEXITED(status)) { 1695 error("%s: exited abnormally", __func__); 1696 goto fail; 1697 } 1698 if (WEXITSTATUS(status) != 0) { 1699 error("%s: exited with status %d", 1700 __func__, WEXITSTATUS(status)); 1701 goto fail; 1702 } 1703 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1704 error("%s: buffer error: %s", __func__, ssh_err(r)); 1705 goto fail; 1706 } 1707 if (rversion != version) { 1708 error("%s: bad version", __func__); 1709 goto fail; 1710 } 1711 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1712 error("%s: buffer error: %s", __func__, ssh_err(r)); 1713 fail: 1714 signal(SIGCHLD, osigchld); 1715 sshbuf_free(b); 1716 return -1; 1717 } 1718 signal(SIGCHLD, osigchld); 1719 sshbuf_free(b); 1720 1721 return 0; 1722 } 1723 1724 int 1725 userauth_hostbased(Authctxt *authctxt) 1726 { 1727 struct ssh *ssh = active_state; 1728 struct sshkey *private = NULL; 1729 struct sshbuf *b = NULL; 1730 const char *service; 1731 u_char *sig = NULL, *keyblob = NULL; 1732 char *fp = NULL, *chost = NULL, *lname = NULL; 1733 size_t siglen = 0, keylen = 0; 1734 int i, r, success = 0; 1735 1736 if (authctxt->ktypes == NULL) { 1737 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1738 authctxt->ktypes = authctxt->oktypes; 1739 } 1740 1741 /* 1742 * Work through each listed type pattern in HostbasedKeyTypes, 1743 * trying each hostkey that matches the type in turn. 1744 */ 1745 for (;;) { 1746 if (authctxt->active_ktype == NULL) 1747 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1748 if (authctxt->active_ktype == NULL || 1749 *authctxt->active_ktype == '\0') 1750 break; 1751 debug3("%s: trying key type %s", __func__, 1752 authctxt->active_ktype); 1753 1754 /* check for a useful key */ 1755 private = NULL; 1756 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1757 if (authctxt->sensitive->keys[i] == NULL || 1758 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1759 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1760 continue; 1761 if (match_pattern_list( 1762 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1763 authctxt->active_ktype, 0) != 1) 1764 continue; 1765 /* we take and free the key */ 1766 private = authctxt->sensitive->keys[i]; 1767 authctxt->sensitive->keys[i] = NULL; 1768 break; 1769 } 1770 /* Found one */ 1771 if (private != NULL) 1772 break; 1773 /* No more keys of this type; advance */ 1774 authctxt->active_ktype = NULL; 1775 } 1776 if (private == NULL) { 1777 free(authctxt->oktypes); 1778 authctxt->oktypes = authctxt->ktypes = NULL; 1779 authctxt->active_ktype = NULL; 1780 debug("No more client hostkeys for hostbased authentication."); 1781 goto out; 1782 } 1783 1784 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1785 SSH_FP_DEFAULT)) == NULL) { 1786 error("%s: sshkey_fingerprint failed", __func__); 1787 goto out; 1788 } 1789 debug("%s: trying hostkey %s %s", 1790 __func__, sshkey_ssh_name(private), fp); 1791 1792 /* figure out a name for the client host */ 1793 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1794 error("%s: cannot get local ipaddr/name", __func__); 1795 goto out; 1796 } 1797 1798 /* XXX sshbuf_put_stringf? */ 1799 xasprintf(&chost, "%s.", lname); 1800 debug2("%s: chost %s", __func__, chost); 1801 1802 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1803 authctxt->service; 1804 1805 /* construct data */ 1806 if ((b = sshbuf_new()) == NULL) { 1807 error("%s: sshbuf_new failed", __func__); 1808 goto out; 1809 } 1810 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1811 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1812 goto out; 1813 } 1814 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1815 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1816 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1817 (r = sshbuf_put_cstring(b, service)) != 0 || 1818 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1819 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1820 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1821 (r = sshbuf_put_cstring(b, chost)) != 0 || 1822 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1823 error("%s: buffer error: %s", __func__, ssh_err(r)); 1824 goto out; 1825 } 1826 1827 #ifdef DEBUG_PK 1828 sshbuf_dump(b, stderr); 1829 #endif 1830 if (authctxt->sensitive->external_keysign) 1831 r = ssh_keysign(private, &sig, &siglen, 1832 sshbuf_ptr(b), sshbuf_len(b)); 1833 else if ((r = sshkey_sign(private, &sig, &siglen, 1834 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1835 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1836 if (r != 0) { 1837 error("sign using hostkey %s %s failed", 1838 sshkey_ssh_name(private), fp); 1839 goto out; 1840 } 1841 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1842 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1843 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1844 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1845 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1846 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1847 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1848 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1849 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1850 (r = sshpkt_send(ssh)) != 0) { 1851 error("%s: packet error: %s", __func__, ssh_err(r)); 1852 goto out; 1853 } 1854 success = 1; 1855 1856 out: 1857 if (sig != NULL) { 1858 explicit_bzero(sig, siglen); 1859 free(sig); 1860 } 1861 free(keyblob); 1862 free(lname); 1863 free(fp); 1864 free(chost); 1865 sshkey_free(private); 1866 sshbuf_free(b); 1867 1868 return success; 1869 } 1870 1871 /* find auth method */ 1872 1873 /* 1874 * given auth method name, if configurable options permit this method fill 1875 * in auth_ident field and return true, otherwise return false. 1876 */ 1877 static int 1878 authmethod_is_enabled(Authmethod *method) 1879 { 1880 if (method == NULL) 1881 return 0; 1882 /* return false if options indicate this method is disabled */ 1883 if (method->enabled == NULL || *method->enabled == 0) 1884 return 0; 1885 /* return false if batch mode is enabled but method needs interactive mode */ 1886 if (method->batch_flag != NULL && *method->batch_flag != 0) 1887 return 0; 1888 return 1; 1889 } 1890 1891 static Authmethod * 1892 authmethod_lookup(const char *name) 1893 { 1894 Authmethod *method = NULL; 1895 if (name != NULL) 1896 for (method = authmethods; method->name != NULL; method++) 1897 if (strcmp(name, method->name) == 0) 1898 return method; 1899 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1900 return NULL; 1901 } 1902 1903 /* XXX internal state */ 1904 static Authmethod *current = NULL; 1905 static char *supported = NULL; 1906 static char *preferred = NULL; 1907 1908 /* 1909 * Given the authentication method list sent by the server, return the 1910 * next method we should try. If the server initially sends a nil list, 1911 * use a built-in default list. 1912 */ 1913 static Authmethod * 1914 authmethod_get(char *authlist) 1915 { 1916 char *name = NULL; 1917 u_int next; 1918 1919 /* Use a suitable default if we're passed a nil list. */ 1920 if (authlist == NULL || strlen(authlist) == 0) 1921 authlist = options.preferred_authentications; 1922 1923 if (supported == NULL || strcmp(authlist, supported) != 0) { 1924 debug3("start over, passed a different list %s", authlist); 1925 free(supported); 1926 supported = xstrdup(authlist); 1927 preferred = options.preferred_authentications; 1928 debug3("preferred %s", preferred); 1929 current = NULL; 1930 } else if (current != NULL && authmethod_is_enabled(current)) 1931 return current; 1932 1933 for (;;) { 1934 if ((name = match_list(preferred, supported, &next)) == NULL) { 1935 debug("No more authentication methods to try."); 1936 current = NULL; 1937 return NULL; 1938 } 1939 preferred += next; 1940 debug3("authmethod_lookup %s", name); 1941 debug3("remaining preferred: %s", preferred); 1942 if ((current = authmethod_lookup(name)) != NULL && 1943 authmethod_is_enabled(current)) { 1944 debug3("authmethod_is_enabled %s", name); 1945 debug("Next authentication method: %s", name); 1946 free(name); 1947 return current; 1948 } 1949 free(name); 1950 } 1951 } 1952 1953 static char * 1954 authmethods_get(void) 1955 { 1956 Authmethod *method = NULL; 1957 Buffer b; 1958 char *list; 1959 1960 buffer_init(&b); 1961 for (method = authmethods; method->name != NULL; method++) { 1962 if (authmethod_is_enabled(method)) { 1963 if (buffer_len(&b) > 0) 1964 buffer_append(&b, ",", 1); 1965 buffer_append(&b, method->name, strlen(method->name)); 1966 } 1967 } 1968 if ((list = sshbuf_dup_string(&b)) == NULL) 1969 fatal("%s: sshbuf_dup_string failed", __func__); 1970 buffer_free(&b); 1971 return list; 1972 } 1973 1974
