sshconnect2.c revision 1.1.1.13
1 /* $OpenBSD: sshconnect2.c,v 1.239 2016/02/23 01:34:14 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 <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "hostfile.h" 67 #include "ssherr.h" 68 69 #ifdef GSSAPI 70 #include "ssh-gss.h" 71 #endif 72 73 /* import */ 74 extern char *client_version_string; 75 extern char *server_version_string; 76 extern Options options; 77 78 /* 79 * SSH2 key exchange 80 */ 81 82 u_char *session_id2 = NULL; 83 u_int session_id2_len = 0; 84 85 char *xxx_host; 86 struct sockaddr *xxx_hostaddr; 87 88 static int 89 verify_host_key_callback(Key *hostkey, struct ssh *ssh) 90 { 91 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 92 fatal("Host key verification failed."); 93 return 0; 94 } 95 96 static char * 97 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 98 { 99 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 100 size_t maxlen; 101 struct hostkeys *hostkeys; 102 int ktype; 103 u_int i; 104 105 /* Find all hostkeys for this hostname */ 106 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 107 hostkeys = init_hostkeys(); 108 for (i = 0; i < options.num_user_hostfiles; i++) 109 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 110 for (i = 0; i < options.num_system_hostfiles; i++) 111 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 112 113 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 114 maxlen = strlen(avail) + 1; 115 first = xmalloc(maxlen); 116 last = xmalloc(maxlen); 117 *first = *last = '\0'; 118 119 #define ALG_APPEND(to, from) \ 120 do { \ 121 if (*to != '\0') \ 122 strlcat(to, ",", maxlen); \ 123 strlcat(to, from, maxlen); \ 124 } while (0) 125 126 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 127 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 128 fatal("%s: unknown alg %s", __func__, alg); 129 if (lookup_key_in_hostkeys_by_type(hostkeys, 130 sshkey_type_plain(ktype), NULL)) 131 ALG_APPEND(first, alg); 132 else 133 ALG_APPEND(last, alg); 134 } 135 #undef ALG_APPEND 136 xasprintf(&ret, "%s%s%s", first, 137 (*first == '\0' || *last == '\0') ? "" : ",", last); 138 if (*first != '\0') 139 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 140 141 free(first); 142 free(last); 143 free(hostname); 144 free(oavail); 145 free_hostkeys(hostkeys); 146 147 return ret; 148 } 149 150 void 151 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 152 { 153 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 154 char *s; 155 struct kex *kex; 156 int r; 157 158 xxx_host = host; 159 xxx_hostaddr = hostaddr; 160 161 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 162 fatal("%s: kex_names_cat", __func__); 163 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 164 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 165 compat_cipher_proposal(options.ciphers); 166 myproposal[PROPOSAL_ENC_ALGS_STOC] = 167 compat_cipher_proposal(options.ciphers); 168 if (options.compression) { 169 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 170 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib (at) openssh.com,zlib,none"; 171 } else { 172 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 173 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib (at) openssh.com,zlib"; 174 } 175 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 176 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 177 if (options.hostkeyalgorithms != NULL) { 178 if (kex_assemble_names(KEX_DEFAULT_PK_ALG, 179 &options.hostkeyalgorithms) != 0) 180 fatal("%s: kex_assemble_namelist", __func__); 181 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 182 compat_pkalg_proposal(options.hostkeyalgorithms); 183 } else { 184 /* Enforce default */ 185 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 186 /* Prefer algorithms that we already have keys for */ 187 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 188 compat_pkalg_proposal( 189 order_hostkeyalgs(host, hostaddr, port)); 190 } 191 192 if (options.rekey_limit || options.rekey_interval) 193 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 194 (time_t)options.rekey_interval); 195 196 /* start key exchange */ 197 if ((r = kex_setup(active_state, myproposal)) != 0) 198 fatal("kex_setup: %s", ssh_err(r)); 199 kex = active_state->kex; 200 #ifdef WITH_OPENSSL 201 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 202 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 203 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 204 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 205 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 206 #endif 207 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 208 kex->client_version_string=client_version_string; 209 kex->server_version_string=server_version_string; 210 kex->verify_host_key=&verify_host_key_callback; 211 212 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 213 214 /* remove ext-info from the KEX proposals for rekeying */ 215 myproposal[PROPOSAL_KEX_ALGS] = 216 compat_kex_proposal(options.kex_algorithms); 217 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 218 fatal("kex_prop2buf: %s", ssh_err(r)); 219 220 session_id2 = kex->session_id; 221 session_id2_len = kex->session_id_len; 222 223 #ifdef DEBUG_KEXDH 224 /* send 1st encrypted/maced/compressed message */ 225 packet_start(SSH2_MSG_IGNORE); 226 packet_put_cstring("markus"); 227 packet_send(); 228 packet_write_wait(); 229 #endif 230 } 231 232 /* 233 * Authenticate user 234 */ 235 236 typedef struct cauthctxt Authctxt; 237 typedef struct cauthmethod Authmethod; 238 typedef struct identity Identity; 239 typedef struct idlist Idlist; 240 241 struct identity { 242 TAILQ_ENTRY(identity) next; 243 int agent_fd; /* >=0 if agent supports key */ 244 struct sshkey *key; /* public/private key */ 245 char *filename; /* comment for agent-only keys */ 246 int tried; 247 int isprivate; /* key points to the private key */ 248 int userprovided; 249 }; 250 TAILQ_HEAD(idlist, identity); 251 252 struct cauthctxt { 253 const char *server_user; 254 const char *local_user; 255 const char *host; 256 const char *service; 257 struct cauthmethod *method; 258 sig_atomic_t success; 259 char *authlist; 260 int attempt; 261 /* pubkey */ 262 struct idlist keys; 263 int agent_fd; 264 /* hostbased */ 265 Sensitive *sensitive; 266 char *oktypes, *ktypes; 267 const char *active_ktype; 268 /* kbd-interactive */ 269 int info_req_seen; 270 /* generic */ 271 void *methoddata; 272 }; 273 274 struct cauthmethod { 275 char *name; /* string to compare against server's list */ 276 int (*userauth)(Authctxt *authctxt); 277 void (*cleanup)(Authctxt *authctxt); 278 int *enabled; /* flag in option struct that enables method */ 279 int *batch_flag; /* flag in option struct that disables method */ 280 }; 281 282 int input_userauth_service_accept(int, u_int32_t, void *); 283 int input_userauth_ext_info(int, u_int32_t, void *); 284 int input_userauth_success(int, u_int32_t, void *); 285 int input_userauth_success_unexpected(int, u_int32_t, void *); 286 int input_userauth_failure(int, u_int32_t, void *); 287 int input_userauth_banner(int, u_int32_t, void *); 288 int input_userauth_error(int, u_int32_t, void *); 289 int input_userauth_info_req(int, u_int32_t, void *); 290 int input_userauth_pk_ok(int, u_int32_t, void *); 291 int input_userauth_passwd_changereq(int, u_int32_t, void *); 292 293 int userauth_none(Authctxt *); 294 int userauth_pubkey(Authctxt *); 295 int userauth_passwd(Authctxt *); 296 int userauth_kbdint(Authctxt *); 297 int userauth_hostbased(Authctxt *); 298 299 #ifdef GSSAPI 300 int userauth_gssapi(Authctxt *authctxt); 301 int input_gssapi_response(int type, u_int32_t, void *); 302 int input_gssapi_token(int type, u_int32_t, void *); 303 int input_gssapi_hash(int type, u_int32_t, void *); 304 int input_gssapi_error(int, u_int32_t, void *); 305 int input_gssapi_errtok(int, u_int32_t, void *); 306 #endif 307 308 void userauth(Authctxt *, char *); 309 310 static int sign_and_send_pubkey(Authctxt *, Identity *); 311 static void pubkey_prepare(Authctxt *); 312 static void pubkey_cleanup(Authctxt *); 313 static Key *load_identity_file(Identity *); 314 315 static Authmethod *authmethod_get(char *authlist); 316 static Authmethod *authmethod_lookup(const char *name); 317 static char *authmethods_get(void); 318 319 Authmethod authmethods[] = { 320 #ifdef GSSAPI 321 {"gssapi-with-mic", 322 userauth_gssapi, 323 NULL, 324 &options.gss_authentication, 325 NULL}, 326 #endif 327 {"hostbased", 328 userauth_hostbased, 329 NULL, 330 &options.hostbased_authentication, 331 NULL}, 332 {"publickey", 333 userauth_pubkey, 334 NULL, 335 &options.pubkey_authentication, 336 NULL}, 337 {"keyboard-interactive", 338 userauth_kbdint, 339 NULL, 340 &options.kbd_interactive_authentication, 341 &options.batch_mode}, 342 {"password", 343 userauth_passwd, 344 NULL, 345 &options.password_authentication, 346 &options.batch_mode}, 347 {"none", 348 userauth_none, 349 NULL, 350 NULL, 351 NULL}, 352 {NULL, NULL, NULL, NULL, NULL} 353 }; 354 355 void 356 ssh_userauth2(const char *local_user, const char *server_user, char *host, 357 Sensitive *sensitive) 358 { 359 struct ssh *ssh = active_state; 360 Authctxt authctxt; 361 int r; 362 363 if (options.challenge_response_authentication) 364 options.kbd_interactive_authentication = 1; 365 if (options.preferred_authentications == NULL) 366 options.preferred_authentications = authmethods_get(); 367 368 /* setup authentication context */ 369 memset(&authctxt, 0, sizeof(authctxt)); 370 pubkey_prepare(&authctxt); 371 authctxt.server_user = server_user; 372 authctxt.local_user = local_user; 373 authctxt.host = host; 374 authctxt.service = "ssh-connection"; /* service name */ 375 authctxt.success = 0; 376 authctxt.method = authmethod_lookup("none"); 377 authctxt.authlist = NULL; 378 authctxt.methoddata = NULL; 379 authctxt.sensitive = sensitive; 380 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 381 authctxt.info_req_seen = 0; 382 authctxt.agent_fd = -1; 383 if (authctxt.method == NULL) 384 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 385 386 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 387 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 388 (r = sshpkt_send(ssh)) != 0) 389 fatal("%s: %s", __func__, ssh_err(r)); 390 391 ssh_dispatch_init(ssh, &input_userauth_error); 392 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 393 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 394 ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 395 396 pubkey_cleanup(&authctxt); 397 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 398 399 debug("Authentication succeeded (%s).", authctxt.method->name); 400 } 401 402 /* ARGSUSED */ 403 int 404 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt) 405 { 406 Authctxt *authctxt = ctxt; 407 struct ssh *ssh = active_state; 408 int r; 409 410 if (ssh_packet_remaining(ssh) > 0) { 411 char *reply; 412 413 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 414 goto out; 415 debug2("service_accept: %s", reply); 416 free(reply); 417 } else { 418 debug2("buggy server: service_accept w/o service"); 419 } 420 if ((r = sshpkt_get_end(ssh)) != 0) 421 goto out; 422 debug("SSH2_MSG_SERVICE_ACCEPT received"); 423 424 /* initial userauth request */ 425 userauth_none(authctxt); 426 427 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 428 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 429 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 430 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 431 r = 0; 432 out: 433 return r; 434 } 435 436 /* ARGSUSED */ 437 int 438 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt) 439 { 440 return kex_input_ext_info(type, seqnr, active_state); 441 } 442 443 void 444 userauth(Authctxt *authctxt, char *authlist) 445 { 446 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 447 authctxt->method->cleanup(authctxt); 448 449 free(authctxt->methoddata); 450 authctxt->methoddata = NULL; 451 if (authlist == NULL) { 452 authlist = authctxt->authlist; 453 } else { 454 free(authctxt->authlist); 455 authctxt->authlist = authlist; 456 } 457 for (;;) { 458 Authmethod *method = authmethod_get(authlist); 459 if (method == NULL) 460 fatal("Permission denied (%s).", authlist); 461 authctxt->method = method; 462 463 /* reset the per method handler */ 464 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 465 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 466 467 /* and try new method */ 468 if (method->userauth(authctxt) != 0) { 469 debug2("we sent a %s packet, wait for reply", method->name); 470 break; 471 } else { 472 debug2("we did not send a packet, disable method"); 473 method->enabled = NULL; 474 } 475 } 476 } 477 478 /* ARGSUSED */ 479 int 480 input_userauth_error(int type, u_int32_t seq, void *ctxt) 481 { 482 fatal("input_userauth_error: bad message during authentication: " 483 "type %d", type); 484 return 0; 485 } 486 487 /* ARGSUSED */ 488 int 489 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 490 { 491 char *msg, *raw, *lang; 492 u_int len; 493 494 debug3("input_userauth_banner"); 495 raw = packet_get_string(&len); 496 lang = packet_get_string(NULL); 497 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 498 if (len > 65536) 499 len = 65536; 500 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 501 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 502 fprintf(stderr, "%s", msg); 503 free(msg); 504 } 505 free(raw); 506 free(lang); 507 return 0; 508 } 509 510 /* ARGSUSED */ 511 int 512 input_userauth_success(int type, u_int32_t seq, void *ctxt) 513 { 514 Authctxt *authctxt = ctxt; 515 516 if (authctxt == NULL) 517 fatal("input_userauth_success: no authentication context"); 518 free(authctxt->authlist); 519 authctxt->authlist = NULL; 520 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 521 authctxt->method->cleanup(authctxt); 522 free(authctxt->methoddata); 523 authctxt->methoddata = NULL; 524 authctxt->success = 1; /* break out */ 525 return 0; 526 } 527 528 int 529 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 530 { 531 Authctxt *authctxt = ctxt; 532 533 if (authctxt == NULL) 534 fatal("%s: no authentication context", __func__); 535 536 fatal("Unexpected authentication success during %s.", 537 authctxt->method->name); 538 return 0; 539 } 540 541 /* ARGSUSED */ 542 int 543 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 544 { 545 Authctxt *authctxt = ctxt; 546 char *authlist = NULL; 547 int partial; 548 549 if (authctxt == NULL) 550 fatal("input_userauth_failure: no authentication context"); 551 552 authlist = packet_get_string(NULL); 553 partial = packet_get_char(); 554 packet_check_eom(); 555 556 if (partial != 0) { 557 logit("Authenticated with partial success."); 558 /* reset state */ 559 pubkey_cleanup(authctxt); 560 pubkey_prepare(authctxt); 561 } 562 debug("Authentications that can continue: %s", authlist); 563 564 userauth(authctxt, authlist); 565 return 0; 566 } 567 568 /* ARGSUSED */ 569 int 570 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 571 { 572 Authctxt *authctxt = ctxt; 573 Key *key = NULL; 574 Identity *id = NULL; 575 Buffer b; 576 int pktype, sent = 0; 577 u_int alen, blen; 578 char *pkalg, *fp; 579 u_char *pkblob; 580 581 if (authctxt == NULL) 582 fatal("input_userauth_pk_ok: no authentication context"); 583 if (datafellows & SSH_BUG_PKOK) { 584 /* this is similar to SSH_BUG_PKAUTH */ 585 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 586 pkblob = packet_get_string(&blen); 587 buffer_init(&b); 588 buffer_append(&b, pkblob, blen); 589 pkalg = buffer_get_string(&b, &alen); 590 buffer_free(&b); 591 } else { 592 pkalg = packet_get_string(&alen); 593 pkblob = packet_get_string(&blen); 594 } 595 packet_check_eom(); 596 597 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 598 599 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 600 debug("unknown pkalg %s", pkalg); 601 goto done; 602 } 603 if ((key = key_from_blob(pkblob, blen)) == NULL) { 604 debug("no key from blob. pkalg %s", pkalg); 605 goto done; 606 } 607 if (key->type != pktype) { 608 error("input_userauth_pk_ok: type mismatch " 609 "for decoded key (received %d, expected %d)", 610 key->type, pktype); 611 goto done; 612 } 613 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 614 SSH_FP_DEFAULT)) == NULL) 615 goto done; 616 debug2("input_userauth_pk_ok: fp %s", fp); 617 free(fp); 618 619 /* 620 * search keys in the reverse order, because last candidate has been 621 * moved to the end of the queue. this also avoids confusion by 622 * duplicate keys 623 */ 624 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 625 if (key_equal(key, id->key)) { 626 sent = sign_and_send_pubkey(authctxt, id); 627 break; 628 } 629 } 630 done: 631 if (key != NULL) 632 key_free(key); 633 free(pkalg); 634 free(pkblob); 635 636 /* try another method if we did not send a packet */ 637 if (sent == 0) 638 userauth(authctxt, NULL); 639 return 0; 640 } 641 642 #ifdef GSSAPI 643 int 644 userauth_gssapi(Authctxt *authctxt) 645 { 646 Gssctxt *gssctxt = NULL; 647 static gss_OID_set gss_supported = NULL; 648 static u_int mech = 0; 649 OM_uint32 min; 650 int ok = 0; 651 652 /* Try one GSSAPI method at a time, rather than sending them all at 653 * once. */ 654 655 if (gss_supported == NULL) 656 gss_indicate_mechs(&min, &gss_supported); 657 658 /* Check to see if the mechanism is usable before we offer it */ 659 while (mech < gss_supported->count && !ok) { 660 /* My DER encoding requires length<128 */ 661 if (gss_supported->elements[mech].length < 128 && 662 ssh_gssapi_check_mechanism(&gssctxt, 663 &gss_supported->elements[mech], authctxt->host)) { 664 ok = 1; /* Mechanism works */ 665 } else { 666 mech++; 667 } 668 } 669 670 if (!ok) 671 return 0; 672 673 authctxt->methoddata=(void *)gssctxt; 674 675 packet_start(SSH2_MSG_USERAUTH_REQUEST); 676 packet_put_cstring(authctxt->server_user); 677 packet_put_cstring(authctxt->service); 678 packet_put_cstring(authctxt->method->name); 679 680 packet_put_int(1); 681 682 packet_put_int((gss_supported->elements[mech].length) + 2); 683 packet_put_char(SSH_GSS_OIDTYPE); 684 packet_put_char(gss_supported->elements[mech].length); 685 packet_put_raw(gss_supported->elements[mech].elements, 686 gss_supported->elements[mech].length); 687 688 packet_send(); 689 690 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 691 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 692 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 693 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 694 695 mech++; /* Move along to next candidate */ 696 697 return 1; 698 } 699 700 static OM_uint32 701 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 702 { 703 Authctxt *authctxt = ctxt; 704 Gssctxt *gssctxt = authctxt->methoddata; 705 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 706 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 707 gss_buffer_desc gssbuf; 708 OM_uint32 status, ms, flags; 709 Buffer b; 710 711 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 712 recv_tok, &send_tok, &flags); 713 714 if (send_tok.length > 0) { 715 if (GSS_ERROR(status)) 716 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 717 else 718 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 719 720 packet_put_string(send_tok.value, send_tok.length); 721 packet_send(); 722 gss_release_buffer(&ms, &send_tok); 723 } 724 725 if (status == GSS_S_COMPLETE) { 726 /* send either complete or MIC, depending on mechanism */ 727 if (!(flags & GSS_C_INTEG_FLAG)) { 728 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 729 packet_send(); 730 } else { 731 ssh_gssapi_buildmic(&b, authctxt->server_user, 732 authctxt->service, "gssapi-with-mic"); 733 734 gssbuf.value = buffer_ptr(&b); 735 gssbuf.length = buffer_len(&b); 736 737 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 738 739 if (!GSS_ERROR(status)) { 740 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 741 packet_put_string(mic.value, mic.length); 742 743 packet_send(); 744 } 745 746 buffer_free(&b); 747 gss_release_buffer(&ms, &mic); 748 } 749 } 750 751 return status; 752 } 753 754 /* ARGSUSED */ 755 int 756 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 757 { 758 Authctxt *authctxt = ctxt; 759 Gssctxt *gssctxt; 760 int oidlen; 761 char *oidv; 762 763 if (authctxt == NULL) 764 fatal("input_gssapi_response: no authentication context"); 765 gssctxt = authctxt->methoddata; 766 767 /* Setup our OID */ 768 oidv = packet_get_string(&oidlen); 769 770 if (oidlen <= 2 || 771 oidv[0] != SSH_GSS_OIDTYPE || 772 oidv[1] != oidlen - 2) { 773 free(oidv); 774 debug("Badly encoded mechanism OID received"); 775 userauth(authctxt, NULL); 776 return 0; 777 } 778 779 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 780 fatal("Server returned different OID than expected"); 781 782 packet_check_eom(); 783 784 free(oidv); 785 786 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 787 /* Start again with next method on list */ 788 debug("Trying to start again"); 789 userauth(authctxt, NULL); 790 return 0; 791 } 792 return 0; 793 } 794 795 /* ARGSUSED */ 796 int 797 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 798 { 799 Authctxt *authctxt = ctxt; 800 gss_buffer_desc recv_tok; 801 OM_uint32 status; 802 u_int slen; 803 804 if (authctxt == NULL) 805 fatal("input_gssapi_response: no authentication context"); 806 807 recv_tok.value = packet_get_string(&slen); 808 recv_tok.length = slen; /* safe typecast */ 809 810 packet_check_eom(); 811 812 status = process_gssapi_token(ctxt, &recv_tok); 813 814 free(recv_tok.value); 815 816 if (GSS_ERROR(status)) { 817 /* Start again with the next method in the list */ 818 userauth(authctxt, NULL); 819 return 0; 820 } 821 return 0; 822 } 823 824 /* ARGSUSED */ 825 int 826 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 827 { 828 Authctxt *authctxt = ctxt; 829 Gssctxt *gssctxt; 830 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 831 gss_buffer_desc recv_tok; 832 OM_uint32 ms; 833 u_int len; 834 835 if (authctxt == NULL) 836 fatal("input_gssapi_response: no authentication context"); 837 gssctxt = authctxt->methoddata; 838 839 recv_tok.value = packet_get_string(&len); 840 recv_tok.length = len; 841 842 packet_check_eom(); 843 844 /* Stick it into GSSAPI and see what it says */ 845 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 846 &recv_tok, &send_tok, NULL); 847 848 free(recv_tok.value); 849 gss_release_buffer(&ms, &send_tok); 850 851 /* Server will be returning a failed packet after this one */ 852 return 0; 853 } 854 855 /* ARGSUSED */ 856 int 857 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 858 { 859 char *msg; 860 char *lang; 861 862 /* maj */(void)packet_get_int(); 863 /* min */(void)packet_get_int(); 864 msg=packet_get_string(NULL); 865 lang=packet_get_string(NULL); 866 867 packet_check_eom(); 868 869 debug("Server GSSAPI Error:\n%s", msg); 870 free(msg); 871 free(lang); 872 return 0; 873 } 874 #endif /* GSSAPI */ 875 876 int 877 userauth_none(Authctxt *authctxt) 878 { 879 /* initial userauth request */ 880 packet_start(SSH2_MSG_USERAUTH_REQUEST); 881 packet_put_cstring(authctxt->server_user); 882 packet_put_cstring(authctxt->service); 883 packet_put_cstring(authctxt->method->name); 884 packet_send(); 885 return 1; 886 } 887 888 int 889 userauth_passwd(Authctxt *authctxt) 890 { 891 static int attempt = 0; 892 char prompt[150]; 893 char *password; 894 const char *host = options.host_key_alias ? options.host_key_alias : 895 authctxt->host; 896 897 if (attempt++ >= options.number_of_password_prompts) 898 return 0; 899 900 if (attempt != 1) 901 error("Permission denied, please try again."); 902 903 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 904 authctxt->server_user, host); 905 password = read_passphrase(prompt, 0); 906 packet_start(SSH2_MSG_USERAUTH_REQUEST); 907 packet_put_cstring(authctxt->server_user); 908 packet_put_cstring(authctxt->service); 909 packet_put_cstring(authctxt->method->name); 910 packet_put_char(0); 911 packet_put_cstring(password); 912 explicit_bzero(password, strlen(password)); 913 free(password); 914 packet_add_padding(64); 915 packet_send(); 916 917 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 918 &input_userauth_passwd_changereq); 919 920 return 1; 921 } 922 923 /* 924 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 925 */ 926 /* ARGSUSED */ 927 int 928 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 929 { 930 Authctxt *authctxt = ctxt; 931 char *info, *lang, *password = NULL, *retype = NULL; 932 char prompt[150]; 933 const char *host = options.host_key_alias ? options.host_key_alias : 934 authctxt->host; 935 936 debug2("input_userauth_passwd_changereq"); 937 938 if (authctxt == NULL) 939 fatal("input_userauth_passwd_changereq: " 940 "no authentication context"); 941 942 info = packet_get_string(NULL); 943 lang = packet_get_string(NULL); 944 if (strlen(info) > 0) 945 logit("%s", info); 946 free(info); 947 free(lang); 948 packet_start(SSH2_MSG_USERAUTH_REQUEST); 949 packet_put_cstring(authctxt->server_user); 950 packet_put_cstring(authctxt->service); 951 packet_put_cstring(authctxt->method->name); 952 packet_put_char(1); /* additional info */ 953 snprintf(prompt, sizeof(prompt), 954 "Enter %.30s@%.128s's old password: ", 955 authctxt->server_user, host); 956 password = read_passphrase(prompt, 0); 957 packet_put_cstring(password); 958 explicit_bzero(password, strlen(password)); 959 free(password); 960 password = NULL; 961 while (password == NULL) { 962 snprintf(prompt, sizeof(prompt), 963 "Enter %.30s@%.128s's new password: ", 964 authctxt->server_user, host); 965 password = read_passphrase(prompt, RP_ALLOW_EOF); 966 if (password == NULL) { 967 /* bail out */ 968 return 0; 969 } 970 snprintf(prompt, sizeof(prompt), 971 "Retype %.30s@%.128s's new password: ", 972 authctxt->server_user, host); 973 retype = read_passphrase(prompt, 0); 974 if (strcmp(password, retype) != 0) { 975 explicit_bzero(password, strlen(password)); 976 free(password); 977 logit("Mismatch; try again, EOF to quit."); 978 password = NULL; 979 } 980 explicit_bzero(retype, strlen(retype)); 981 free(retype); 982 } 983 packet_put_cstring(password); 984 explicit_bzero(password, strlen(password)); 985 free(password); 986 packet_add_padding(64); 987 packet_send(); 988 989 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 990 &input_userauth_passwd_changereq); 991 return 0; 992 } 993 994 static const char * 995 identity_sign_encode(struct identity *id) 996 { 997 struct ssh *ssh = active_state; 998 999 if (id->key->type == KEY_RSA) { 1000 switch (ssh->kex->rsa_sha2) { 1001 case 256: 1002 return "rsa-sha2-256"; 1003 case 512: 1004 return "rsa-sha2-512"; 1005 } 1006 } 1007 return key_ssh_name(id->key); 1008 } 1009 1010 static int 1011 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1012 const u_char *data, size_t datalen, u_int compat) 1013 { 1014 Key *prv; 1015 int ret; 1016 const char *alg; 1017 1018 alg = identity_sign_encode(id); 1019 1020 /* the agent supports this key */ 1021 if (id->agent_fd != -1) 1022 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1023 data, datalen, alg, compat); 1024 1025 /* 1026 * we have already loaded the private key or 1027 * the private key is stored in external hardware 1028 */ 1029 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 1030 return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg, 1031 compat)); 1032 /* load the private key from the file */ 1033 if ((prv = load_identity_file(id)) == NULL) 1034 return SSH_ERR_KEY_NOT_FOUND; 1035 ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1036 sshkey_free(prv); 1037 return (ret); 1038 } 1039 1040 static int 1041 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1042 { 1043 Buffer b; 1044 Identity *private_id; 1045 u_char *blob, *signature; 1046 size_t slen; 1047 u_int bloblen, skip = 0; 1048 int matched, ret = -1, have_sig = 1; 1049 char *fp; 1050 1051 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1052 SSH_FP_DEFAULT)) == NULL) 1053 return 0; 1054 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1055 free(fp); 1056 1057 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1058 /* we cannot handle this key */ 1059 debug3("sign_and_send_pubkey: cannot handle key"); 1060 return 0; 1061 } 1062 /* data to be signed */ 1063 buffer_init(&b); 1064 if (datafellows & SSH_OLD_SESSIONID) { 1065 buffer_append(&b, session_id2, session_id2_len); 1066 skip = session_id2_len; 1067 } else { 1068 buffer_put_string(&b, session_id2, session_id2_len); 1069 skip = buffer_len(&b); 1070 } 1071 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1072 buffer_put_cstring(&b, authctxt->server_user); 1073 buffer_put_cstring(&b, 1074 datafellows & SSH_BUG_PKSERVICE ? 1075 "ssh-userauth" : 1076 authctxt->service); 1077 if (datafellows & SSH_BUG_PKAUTH) { 1078 buffer_put_char(&b, have_sig); 1079 } else { 1080 buffer_put_cstring(&b, authctxt->method->name); 1081 buffer_put_char(&b, have_sig); 1082 buffer_put_cstring(&b, identity_sign_encode(id)); 1083 } 1084 buffer_put_string(&b, blob, bloblen); 1085 1086 /* 1087 * If the key is an certificate, try to find a matching private key 1088 * and use it to complete the signature. 1089 * If no such private key exists, return failure and continue with 1090 * other methods of authentication. 1091 */ 1092 if (key_is_cert(id->key)) { 1093 matched = 0; 1094 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1095 if (sshkey_equal_public(id->key, private_id->key) && 1096 id->key->type != private_id->key->type) { 1097 id = private_id; 1098 matched = 1; 1099 break; 1100 } 1101 } 1102 if (matched) { 1103 debug2("%s: using private key \"%s\"%s for " 1104 "certificate", __func__, id->filename, 1105 id->agent_fd != -1 ? " from agent" : ""); 1106 } else { 1107 /* XXX maybe verbose/error? */ 1108 debug("%s: no private key for certificate " 1109 "\"%s\"", __func__, id->filename); 1110 free(blob); 1111 buffer_free(&b); 1112 return 0; 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 /* Prefer PKCS11 keys that are explicitly listed */ 1296 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1297 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1298 continue; 1299 found = 0; 1300 TAILQ_FOREACH(id2, &files, next) { 1301 if (id2->key == NULL || 1302 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1303 continue; 1304 if (sshkey_equal(id->key, id2->key)) { 1305 TAILQ_REMOVE(&files, id, next); 1306 TAILQ_INSERT_TAIL(preferred, id, next); 1307 found = 1; 1308 break; 1309 } 1310 } 1311 /* If IdentitiesOnly set and key not found then don't use it */ 1312 if (!found && options.identities_only) { 1313 TAILQ_REMOVE(&files, id, next); 1314 explicit_bzero(id, sizeof(*id)); 1315 free(id); 1316 } 1317 } 1318 /* list of certificates specified by user */ 1319 for (i = 0; i < options.num_certificate_files; i++) { 1320 key = options.certificates[i]; 1321 if (!key_is_cert(key) || key->cert == NULL || 1322 key->cert->type != SSH2_CERT_TYPE_USER) 1323 continue; 1324 id = xcalloc(1, sizeof(*id)); 1325 id->agent_fd = -1; 1326 id->key = key; 1327 id->filename = xstrdup(options.certificate_files[i]); 1328 id->userprovided = options.certificate_file_userprovided[i]; 1329 TAILQ_INSERT_TAIL(preferred, id, next); 1330 } 1331 /* list of keys supported by the agent */ 1332 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1333 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1334 debug("%s: ssh_get_authentication_socket: %s", 1335 __func__, ssh_err(r)); 1336 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1337 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1338 debug("%s: ssh_fetch_identitylist: %s", 1339 __func__, ssh_err(r)); 1340 close(agent_fd); 1341 } else { 1342 for (j = 0; j < idlist->nkeys; j++) { 1343 found = 0; 1344 TAILQ_FOREACH(id, &files, next) { 1345 /* 1346 * agent keys from the config file are 1347 * preferred 1348 */ 1349 if (sshkey_equal(idlist->keys[j], id->key)) { 1350 TAILQ_REMOVE(&files, id, next); 1351 TAILQ_INSERT_TAIL(preferred, id, next); 1352 id->agent_fd = agent_fd; 1353 found = 1; 1354 break; 1355 } 1356 } 1357 if (!found && !options.identities_only) { 1358 id = xcalloc(1, sizeof(*id)); 1359 /* XXX "steals" key/comment from idlist */ 1360 id->key = idlist->keys[j]; 1361 id->filename = idlist->comments[j]; 1362 idlist->keys[j] = NULL; 1363 idlist->comments[j] = NULL; 1364 id->agent_fd = agent_fd; 1365 TAILQ_INSERT_TAIL(&agent, id, next); 1366 } 1367 } 1368 ssh_free_identitylist(idlist); 1369 /* append remaining agent keys */ 1370 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1371 TAILQ_REMOVE(&agent, id, next); 1372 TAILQ_INSERT_TAIL(preferred, id, next); 1373 } 1374 authctxt->agent_fd = agent_fd; 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 int 1418 try_identity(Identity *id) 1419 { 1420 if (!id->key) 1421 return (0); 1422 if (key_type_plain(id->key->type) == KEY_RSA && 1423 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1424 debug("Skipped %s key %s for RSA/MD5 server", 1425 key_type(id->key), id->filename); 1426 return (0); 1427 } 1428 return (id->key->type != KEY_RSA1); 1429 } 1430 1431 int 1432 userauth_pubkey(Authctxt *authctxt) 1433 { 1434 Identity *id; 1435 int sent = 0; 1436 1437 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1438 if (id->tried++) 1439 return (0); 1440 /* move key to the end of the queue */ 1441 TAILQ_REMOVE(&authctxt->keys, id, next); 1442 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1443 /* 1444 * send a test message if we have the public key. for 1445 * encrypted keys we cannot do this and have to load the 1446 * private key instead 1447 */ 1448 if (id->key != NULL) { 1449 if (try_identity(id)) { 1450 debug("Offering %s public key: %s", 1451 key_type(id->key), id->filename); 1452 sent = send_pubkey_test(authctxt, id); 1453 } 1454 } else { 1455 debug("Trying private key: %s", id->filename); 1456 id->key = load_identity_file(id); 1457 if (id->key != NULL) { 1458 if (try_identity(id)) { 1459 id->isprivate = 1; 1460 sent = sign_and_send_pubkey( 1461 authctxt, id); 1462 } 1463 key_free(id->key); 1464 id->key = NULL; 1465 } 1466 } 1467 if (sent) 1468 return (sent); 1469 } 1470 return (0); 1471 } 1472 1473 /* 1474 * Send userauth request message specifying keyboard-interactive method. 1475 */ 1476 int 1477 userauth_kbdint(Authctxt *authctxt) 1478 { 1479 static int attempt = 0; 1480 1481 if (attempt++ >= options.number_of_password_prompts) 1482 return 0; 1483 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1484 if (attempt > 1 && !authctxt->info_req_seen) { 1485 debug3("userauth_kbdint: disable: no info_req_seen"); 1486 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1487 return 0; 1488 } 1489 1490 debug2("userauth_kbdint"); 1491 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1492 packet_put_cstring(authctxt->server_user); 1493 packet_put_cstring(authctxt->service); 1494 packet_put_cstring(authctxt->method->name); 1495 packet_put_cstring(""); /* lang */ 1496 packet_put_cstring(options.kbd_interactive_devices ? 1497 options.kbd_interactive_devices : ""); 1498 packet_send(); 1499 1500 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1501 return 1; 1502 } 1503 1504 /* 1505 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1506 */ 1507 int 1508 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1509 { 1510 Authctxt *authctxt = ctxt; 1511 char *name, *inst, *lang, *prompt, *response; 1512 u_int num_prompts, i; 1513 int echo = 0; 1514 1515 debug2("input_userauth_info_req"); 1516 1517 if (authctxt == NULL) 1518 fatal("input_userauth_info_req: no authentication context"); 1519 1520 authctxt->info_req_seen = 1; 1521 1522 name = packet_get_string(NULL); 1523 inst = packet_get_string(NULL); 1524 lang = packet_get_string(NULL); 1525 if (strlen(name) > 0) 1526 logit("%s", name); 1527 if (strlen(inst) > 0) 1528 logit("%s", inst); 1529 free(name); 1530 free(inst); 1531 free(lang); 1532 1533 num_prompts = packet_get_int(); 1534 /* 1535 * Begin to build info response packet based on prompts requested. 1536 * We commit to providing the correct number of responses, so if 1537 * further on we run into a problem that prevents this, we have to 1538 * be sure and clean this up and send a correct error response. 1539 */ 1540 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1541 packet_put_int(num_prompts); 1542 1543 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1544 for (i = 0; i < num_prompts; i++) { 1545 prompt = packet_get_string(NULL); 1546 echo = packet_get_char(); 1547 1548 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1549 1550 packet_put_cstring(response); 1551 explicit_bzero(response, strlen(response)); 1552 free(response); 1553 free(prompt); 1554 } 1555 packet_check_eom(); /* done with parsing incoming message. */ 1556 1557 packet_add_padding(64); 1558 packet_send(); 1559 return 0; 1560 } 1561 1562 static int 1563 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1564 const u_char *data, size_t datalen) 1565 { 1566 struct sshbuf *b; 1567 struct stat st; 1568 pid_t pid; 1569 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1570 u_char rversion = 0, version = 2; 1571 void (*osigchld)(int); 1572 1573 *sigp = NULL; 1574 *lenp = 0; 1575 1576 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1577 error("%s: not installed: %s", __func__, strerror(errno)); 1578 return -1; 1579 } 1580 if (fflush(stdout) != 0) { 1581 error("%s: fflush: %s", __func__, strerror(errno)); 1582 return -1; 1583 } 1584 if (pipe(to) < 0) { 1585 error("%s: pipe: %s", __func__, strerror(errno)); 1586 return -1; 1587 } 1588 if (pipe(from) < 0) { 1589 error("%s: pipe: %s", __func__, strerror(errno)); 1590 return -1; 1591 } 1592 if ((pid = fork()) < 0) { 1593 error("%s: fork: %s", __func__, strerror(errno)); 1594 return -1; 1595 } 1596 osigchld = signal(SIGCHLD, SIG_DFL); 1597 if (pid == 0) { 1598 /* keep the socket on exec */ 1599 fcntl(sock, F_SETFD, 0); 1600 permanently_drop_suid(getuid()); 1601 close(from[0]); 1602 if (dup2(from[1], STDOUT_FILENO) < 0) 1603 fatal("%s: dup2: %s", __func__, strerror(errno)); 1604 close(to[1]); 1605 if (dup2(to[0], STDIN_FILENO) < 0) 1606 fatal("%s: dup2: %s", __func__, strerror(errno)); 1607 close(from[1]); 1608 close(to[0]); 1609 /* Close everything but stdio and the socket */ 1610 for (i = STDERR_FILENO + 1; i < sock; i++) 1611 close(i); 1612 closefrom(sock + 1); 1613 debug3("%s: [child] pid=%ld, exec %s", 1614 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1615 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1616 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1617 strerror(errno)); 1618 } 1619 close(from[1]); 1620 close(to[0]); 1621 1622 if ((b = sshbuf_new()) == NULL) 1623 fatal("%s: sshbuf_new failed", __func__); 1624 /* send # of sock, data to be signed */ 1625 if ((r = sshbuf_put_u32(b, sock) != 0) || 1626 (r = sshbuf_put_string(b, data, datalen)) != 0) 1627 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1628 if (ssh_msg_send(to[1], version, b) == -1) 1629 fatal("%s: couldn't send request", __func__); 1630 sshbuf_reset(b); 1631 r = ssh_msg_recv(from[0], b); 1632 close(from[0]); 1633 close(to[1]); 1634 if (r < 0) { 1635 error("%s: no reply", __func__); 1636 goto fail; 1637 } 1638 1639 errno = 0; 1640 while (waitpid(pid, &status, 0) < 0) { 1641 if (errno != EINTR) { 1642 error("%s: waitpid %ld: %s", 1643 __func__, (long)pid, strerror(errno)); 1644 goto fail; 1645 } 1646 } 1647 if (!WIFEXITED(status)) { 1648 error("%s: exited abnormally", __func__); 1649 goto fail; 1650 } 1651 if (WEXITSTATUS(status) != 0) { 1652 error("%s: exited with status %d", 1653 __func__, WEXITSTATUS(status)); 1654 goto fail; 1655 } 1656 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1657 error("%s: buffer error: %s", __func__, ssh_err(r)); 1658 goto fail; 1659 } 1660 if (rversion != version) { 1661 error("%s: bad version", __func__); 1662 goto fail; 1663 } 1664 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1665 error("%s: buffer error: %s", __func__, ssh_err(r)); 1666 fail: 1667 signal(SIGCHLD, osigchld); 1668 sshbuf_free(b); 1669 return -1; 1670 } 1671 signal(SIGCHLD, osigchld); 1672 sshbuf_free(b); 1673 1674 return 0; 1675 } 1676 1677 int 1678 userauth_hostbased(Authctxt *authctxt) 1679 { 1680 struct ssh *ssh = active_state; 1681 struct sshkey *private = NULL; 1682 struct sshbuf *b = NULL; 1683 const char *service; 1684 u_char *sig = NULL, *keyblob = NULL; 1685 char *fp = NULL, *chost = NULL, *lname = NULL; 1686 size_t siglen = 0, keylen = 0; 1687 int i, r, success = 0; 1688 1689 if (authctxt->ktypes == NULL) { 1690 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1691 authctxt->ktypes = authctxt->oktypes; 1692 } 1693 1694 /* 1695 * Work through each listed type pattern in HostbasedKeyTypes, 1696 * trying each hostkey that matches the type in turn. 1697 */ 1698 for (;;) { 1699 if (authctxt->active_ktype == NULL) 1700 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1701 if (authctxt->active_ktype == NULL || 1702 *authctxt->active_ktype == '\0') 1703 break; 1704 debug3("%s: trying key type %s", __func__, 1705 authctxt->active_ktype); 1706 1707 /* check for a useful key */ 1708 private = NULL; 1709 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1710 if (authctxt->sensitive->keys[i] == NULL || 1711 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1712 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1713 continue; 1714 if (match_pattern_list( 1715 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1716 authctxt->active_ktype, 0) != 1) 1717 continue; 1718 /* we take and free the key */ 1719 private = authctxt->sensitive->keys[i]; 1720 authctxt->sensitive->keys[i] = NULL; 1721 break; 1722 } 1723 /* Found one */ 1724 if (private != NULL) 1725 break; 1726 /* No more keys of this type; advance */ 1727 authctxt->active_ktype = NULL; 1728 } 1729 if (private == NULL) { 1730 free(authctxt->oktypes); 1731 authctxt->oktypes = authctxt->ktypes = NULL; 1732 authctxt->active_ktype = NULL; 1733 debug("No more client hostkeys for hostbased authentication."); 1734 goto out; 1735 } 1736 1737 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1738 SSH_FP_DEFAULT)) == NULL) { 1739 error("%s: sshkey_fingerprint failed", __func__); 1740 goto out; 1741 } 1742 debug("%s: trying hostkey %s %s", 1743 __func__, sshkey_ssh_name(private), fp); 1744 1745 /* figure out a name for the client host */ 1746 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1747 error("%s: cannot get local ipaddr/name", __func__); 1748 goto out; 1749 } 1750 1751 /* XXX sshbuf_put_stringf? */ 1752 xasprintf(&chost, "%s.", lname); 1753 debug2("%s: chost %s", __func__, chost); 1754 1755 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1756 authctxt->service; 1757 1758 /* construct data */ 1759 if ((b = sshbuf_new()) == NULL) { 1760 error("%s: sshbuf_new failed", __func__); 1761 goto out; 1762 } 1763 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1764 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1765 goto out; 1766 } 1767 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1768 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1769 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1770 (r = sshbuf_put_cstring(b, service)) != 0 || 1771 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1772 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1773 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1774 (r = sshbuf_put_cstring(b, chost)) != 0 || 1775 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1776 error("%s: buffer error: %s", __func__, ssh_err(r)); 1777 goto out; 1778 } 1779 1780 #ifdef DEBUG_PK 1781 sshbuf_dump(b, stderr); 1782 #endif 1783 if (authctxt->sensitive->external_keysign) 1784 r = ssh_keysign(private, &sig, &siglen, 1785 sshbuf_ptr(b), sshbuf_len(b)); 1786 else if ((r = sshkey_sign(private, &sig, &siglen, 1787 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1788 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1789 if (r != 0) { 1790 error("sign using hostkey %s %s failed", 1791 sshkey_ssh_name(private), fp); 1792 goto out; 1793 } 1794 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1795 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1796 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1797 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1798 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1799 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1800 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1801 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1802 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1803 (r = sshpkt_send(ssh)) != 0) { 1804 error("%s: packet error: %s", __func__, ssh_err(r)); 1805 goto out; 1806 } 1807 success = 1; 1808 1809 out: 1810 if (sig != NULL) { 1811 explicit_bzero(sig, siglen); 1812 free(sig); 1813 } 1814 free(keyblob); 1815 free(lname); 1816 free(fp); 1817 free(chost); 1818 sshkey_free(private); 1819 sshbuf_free(b); 1820 1821 return success; 1822 } 1823 1824 /* find auth method */ 1825 1826 /* 1827 * given auth method name, if configurable options permit this method fill 1828 * in auth_ident field and return true, otherwise return false. 1829 */ 1830 static int 1831 authmethod_is_enabled(Authmethod *method) 1832 { 1833 if (method == NULL) 1834 return 0; 1835 /* return false if options indicate this method is disabled */ 1836 if (method->enabled == NULL || *method->enabled == 0) 1837 return 0; 1838 /* return false if batch mode is enabled but method needs interactive mode */ 1839 if (method->batch_flag != NULL && *method->batch_flag != 0) 1840 return 0; 1841 return 1; 1842 } 1843 1844 static Authmethod * 1845 authmethod_lookup(const char *name) 1846 { 1847 Authmethod *method = NULL; 1848 if (name != NULL) 1849 for (method = authmethods; method->name != NULL; method++) 1850 if (strcmp(name, method->name) == 0) 1851 return method; 1852 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1853 return NULL; 1854 } 1855 1856 /* XXX internal state */ 1857 static Authmethod *current = NULL; 1858 static char *supported = NULL; 1859 static char *preferred = NULL; 1860 1861 /* 1862 * Given the authentication method list sent by the server, return the 1863 * next method we should try. If the server initially sends a nil list, 1864 * use a built-in default list. 1865 */ 1866 static Authmethod * 1867 authmethod_get(char *authlist) 1868 { 1869 char *name = NULL; 1870 u_int next; 1871 1872 /* Use a suitable default if we're passed a nil list. */ 1873 if (authlist == NULL || strlen(authlist) == 0) 1874 authlist = options.preferred_authentications; 1875 1876 if (supported == NULL || strcmp(authlist, supported) != 0) { 1877 debug3("start over, passed a different list %s", authlist); 1878 free(supported); 1879 supported = xstrdup(authlist); 1880 preferred = options.preferred_authentications; 1881 debug3("preferred %s", preferred); 1882 current = NULL; 1883 } else if (current != NULL && authmethod_is_enabled(current)) 1884 return current; 1885 1886 for (;;) { 1887 if ((name = match_list(preferred, supported, &next)) == NULL) { 1888 debug("No more authentication methods to try."); 1889 current = NULL; 1890 return NULL; 1891 } 1892 preferred += next; 1893 debug3("authmethod_lookup %s", name); 1894 debug3("remaining preferred: %s", preferred); 1895 if ((current = authmethod_lookup(name)) != NULL && 1896 authmethod_is_enabled(current)) { 1897 debug3("authmethod_is_enabled %s", name); 1898 debug("Next authentication method: %s", name); 1899 free(name); 1900 return current; 1901 } 1902 free(name); 1903 } 1904 } 1905 1906 static char * 1907 authmethods_get(void) 1908 { 1909 Authmethod *method = NULL; 1910 Buffer b; 1911 char *list; 1912 1913 buffer_init(&b); 1914 for (method = authmethods; method->name != NULL; method++) { 1915 if (authmethod_is_enabled(method)) { 1916 if (buffer_len(&b) > 0) 1917 buffer_append(&b, ",", 1); 1918 buffer_append(&b, method->name, strlen(method->name)); 1919 } 1920 } 1921 buffer_append(&b, "\0", 1); 1922 list = xstrdup(buffer_ptr(&b)); 1923 buffer_free(&b); 1924 return list; 1925 } 1926 1927
Indexes created Fri Mar 06 19:51:54 UTC 2026