sshconnect2.c revision 1.1.1.10
1 /* $OpenBSD: sshconnect2.c,v 1.223 2015/01/30 11:43:14 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 struct kex *kex; 155 int r; 156 157 xxx_host = host; 158 xxx_hostaddr = hostaddr; 159 160 if (options.ciphers == (char *)-1) { 161 logit("No valid ciphers for protocol version 2 given, using defaults."); 162 options.ciphers = NULL; 163 } 164 if (options.ciphers != NULL) { 165 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 166 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 167 } 168 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 169 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 170 myproposal[PROPOSAL_ENC_ALGS_STOC] = 171 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 172 if (options.compression) { 173 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 174 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib (at) openssh.com,zlib,none"; 175 } else { 176 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 177 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib (at) openssh.com,zlib"; 178 } 179 if (options.macs != NULL) { 180 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 181 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 182 } 183 if (options.hostkeyalgorithms != NULL) 184 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 185 compat_pkalg_proposal(options.hostkeyalgorithms); 186 else { 187 /* Prefer algorithms that we already have keys for */ 188 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 189 compat_pkalg_proposal( 190 order_hostkeyalgs(host, hostaddr, port)); 191 } 192 if (options.kex_algorithms != NULL) 193 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 194 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 195 myproposal[PROPOSAL_KEX_ALGS]); 196 197 if (options.rekey_limit || options.rekey_interval) 198 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 199 (time_t)options.rekey_interval); 200 201 /* start key exchange */ 202 if ((r = kex_setup(active_state, myproposal)) != 0) 203 fatal("kex_setup: %s", ssh_err(r)); 204 kex = active_state->kex; 205 #ifdef WITH_OPENSSL 206 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 207 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 208 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 209 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 210 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 211 #endif 212 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 213 kex->client_version_string=client_version_string; 214 kex->server_version_string=server_version_string; 215 kex->verify_host_key=&verify_host_key_callback; 216 217 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 218 219 if (options.use_roaming && !kex->roaming) { 220 debug("Roaming not allowed by server"); 221 options.use_roaming = 0; 222 } 223 224 session_id2 = kex->session_id; 225 session_id2_len = kex->session_id_len; 226 227 #ifdef DEBUG_KEXDH 228 /* send 1st encrypted/maced/compressed message */ 229 packet_start(SSH2_MSG_IGNORE); 230 packet_put_cstring("markus"); 231 packet_send(); 232 packet_write_wait(); 233 #endif 234 } 235 236 /* 237 * Authenticate user 238 */ 239 240 typedef struct cauthctxt Authctxt; 241 typedef struct cauthmethod Authmethod; 242 typedef struct identity Identity; 243 typedef struct idlist Idlist; 244 245 struct identity { 246 TAILQ_ENTRY(identity) next; 247 int agent_fd; /* >=0 if agent supports key */ 248 struct sshkey *key; /* public/private key */ 249 char *filename; /* comment for agent-only keys */ 250 int tried; 251 int isprivate; /* key points to the private key */ 252 int userprovided; 253 }; 254 TAILQ_HEAD(idlist, identity); 255 256 struct cauthctxt { 257 const char *server_user; 258 const char *local_user; 259 const char *host; 260 const char *service; 261 struct cauthmethod *method; 262 sig_atomic_t success; 263 char *authlist; 264 int attempt; 265 /* pubkey */ 266 struct idlist keys; 267 int agent_fd; 268 /* hostbased */ 269 Sensitive *sensitive; 270 char *oktypes, *ktypes; 271 const char *active_ktype; 272 /* kbd-interactive */ 273 int info_req_seen; 274 /* generic */ 275 void *methoddata; 276 }; 277 278 struct cauthmethod { 279 char *name; /* string to compare against server's list */ 280 int (*userauth)(Authctxt *authctxt); 281 void (*cleanup)(Authctxt *authctxt); 282 int *enabled; /* flag in option struct that enables method */ 283 int *batch_flag; /* flag in option struct that disables method */ 284 }; 285 286 int input_userauth_success(int, u_int32_t, void *); 287 int input_userauth_success_unexpected(int, u_int32_t, void *); 288 int input_userauth_failure(int, u_int32_t, void *); 289 int input_userauth_banner(int, u_int32_t, void *); 290 int input_userauth_error(int, u_int32_t, void *); 291 int input_userauth_info_req(int, u_int32_t, void *); 292 int input_userauth_pk_ok(int, u_int32_t, void *); 293 int input_userauth_passwd_changereq(int, u_int32_t, void *); 294 295 int userauth_none(Authctxt *); 296 int userauth_pubkey(Authctxt *); 297 int userauth_passwd(Authctxt *); 298 int userauth_kbdint(Authctxt *); 299 int userauth_hostbased(Authctxt *); 300 301 #ifdef GSSAPI 302 int userauth_gssapi(Authctxt *authctxt); 303 int input_gssapi_response(int type, u_int32_t, void *); 304 int input_gssapi_token(int type, u_int32_t, void *); 305 int input_gssapi_hash(int type, u_int32_t, void *); 306 int input_gssapi_error(int, u_int32_t, void *); 307 int input_gssapi_errtok(int, u_int32_t, void *); 308 #endif 309 310 void userauth(Authctxt *, char *); 311 312 static int sign_and_send_pubkey(Authctxt *, Identity *); 313 static void pubkey_prepare(Authctxt *); 314 static void pubkey_cleanup(Authctxt *); 315 static Key *load_identity_file(char *, int); 316 317 static Authmethod *authmethod_get(char *authlist); 318 static Authmethod *authmethod_lookup(const char *name); 319 static char *authmethods_get(void); 320 321 Authmethod authmethods[] = { 322 #ifdef GSSAPI 323 {"gssapi-with-mic", 324 userauth_gssapi, 325 NULL, 326 &options.gss_authentication, 327 NULL}, 328 #endif 329 {"hostbased", 330 userauth_hostbased, 331 NULL, 332 &options.hostbased_authentication, 333 NULL}, 334 {"publickey", 335 userauth_pubkey, 336 NULL, 337 &options.pubkey_authentication, 338 NULL}, 339 {"keyboard-interactive", 340 userauth_kbdint, 341 NULL, 342 &options.kbd_interactive_authentication, 343 &options.batch_mode}, 344 {"password", 345 userauth_passwd, 346 NULL, 347 &options.password_authentication, 348 &options.batch_mode}, 349 {"none", 350 userauth_none, 351 NULL, 352 NULL, 353 NULL}, 354 {NULL, NULL, NULL, NULL, NULL} 355 }; 356 357 void 358 ssh_userauth2(const char *local_user, const char *server_user, char *host, 359 Sensitive *sensitive) 360 { 361 Authctxt authctxt; 362 int type; 363 364 if (options.challenge_response_authentication) 365 options.kbd_interactive_authentication = 1; 366 367 packet_start(SSH2_MSG_SERVICE_REQUEST); 368 packet_put_cstring("ssh-userauth"); 369 packet_send(); 370 debug("SSH2_MSG_SERVICE_REQUEST sent"); 371 packet_write_wait(); 372 type = packet_read(); 373 if (type != SSH2_MSG_SERVICE_ACCEPT) 374 fatal("Server denied authentication request: %d", type); 375 if (packet_remaining() > 0) { 376 char *reply = packet_get_string(NULL); 377 debug2("service_accept: %s", reply); 378 free(reply); 379 } else { 380 debug2("buggy server: service_accept w/o service"); 381 } 382 packet_check_eom(); 383 debug("SSH2_MSG_SERVICE_ACCEPT received"); 384 385 if (options.preferred_authentications == NULL) 386 options.preferred_authentications = authmethods_get(); 387 388 /* setup authentication context */ 389 memset(&authctxt, 0, sizeof(authctxt)); 390 pubkey_prepare(&authctxt); 391 authctxt.server_user = server_user; 392 authctxt.local_user = local_user; 393 authctxt.host = host; 394 authctxt.service = "ssh-connection"; /* service name */ 395 authctxt.success = 0; 396 authctxt.method = authmethod_lookup("none"); 397 authctxt.authlist = NULL; 398 authctxt.methoddata = NULL; 399 authctxt.sensitive = sensitive; 400 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 401 authctxt.info_req_seen = 0; 402 authctxt.agent_fd = -1; 403 if (authctxt.method == NULL) 404 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 405 406 /* initial userauth request */ 407 userauth_none(&authctxt); 408 409 dispatch_init(&input_userauth_error); 410 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 411 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 412 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 413 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 414 415 pubkey_cleanup(&authctxt); 416 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 417 418 debug("Authentication succeeded (%s).", authctxt.method->name); 419 } 420 421 void 422 userauth(Authctxt *authctxt, char *authlist) 423 { 424 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 425 authctxt->method->cleanup(authctxt); 426 427 free(authctxt->methoddata); 428 authctxt->methoddata = NULL; 429 if (authlist == NULL) { 430 authlist = authctxt->authlist; 431 } else { 432 free(authctxt->authlist); 433 authctxt->authlist = authlist; 434 } 435 for (;;) { 436 Authmethod *method = authmethod_get(authlist); 437 if (method == NULL) 438 fatal("Permission denied (%s).", authlist); 439 authctxt->method = method; 440 441 /* reset the per method handler */ 442 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 443 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 444 445 /* and try new method */ 446 if (method->userauth(authctxt) != 0) { 447 debug2("we sent a %s packet, wait for reply", method->name); 448 break; 449 } else { 450 debug2("we did not send a packet, disable method"); 451 method->enabled = NULL; 452 } 453 } 454 } 455 456 /* ARGSUSED */ 457 int 458 input_userauth_error(int type, u_int32_t seq, void *ctxt) 459 { 460 fatal("input_userauth_error: bad message during authentication: " 461 "type %d", type); 462 return 0; 463 } 464 465 /* ARGSUSED */ 466 int 467 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 468 { 469 char *msg, *raw, *lang; 470 u_int len; 471 472 debug3("input_userauth_banner"); 473 raw = packet_get_string(&len); 474 lang = packet_get_string(NULL); 475 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 476 if (len > 65536) 477 len = 65536; 478 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 479 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 480 fprintf(stderr, "%s", msg); 481 free(msg); 482 } 483 free(raw); 484 free(lang); 485 return 0; 486 } 487 488 /* ARGSUSED */ 489 int 490 input_userauth_success(int type, u_int32_t seq, void *ctxt) 491 { 492 Authctxt *authctxt = ctxt; 493 494 if (authctxt == NULL) 495 fatal("input_userauth_success: no authentication context"); 496 free(authctxt->authlist); 497 authctxt->authlist = NULL; 498 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 499 authctxt->method->cleanup(authctxt); 500 free(authctxt->methoddata); 501 authctxt->methoddata = NULL; 502 authctxt->success = 1; /* break out */ 503 return 0; 504 } 505 506 int 507 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 508 { 509 Authctxt *authctxt = ctxt; 510 511 if (authctxt == NULL) 512 fatal("%s: no authentication context", __func__); 513 514 fatal("Unexpected authentication success during %s.", 515 authctxt->method->name); 516 return 0; 517 } 518 519 /* ARGSUSED */ 520 int 521 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 522 { 523 Authctxt *authctxt = ctxt; 524 char *authlist = NULL; 525 int partial; 526 527 if (authctxt == NULL) 528 fatal("input_userauth_failure: no authentication context"); 529 530 authlist = packet_get_string(NULL); 531 partial = packet_get_char(); 532 packet_check_eom(); 533 534 if (partial != 0) { 535 logit("Authenticated with partial success."); 536 /* reset state */ 537 pubkey_cleanup(authctxt); 538 pubkey_prepare(authctxt); 539 } 540 debug("Authentications that can continue: %s", authlist); 541 542 userauth(authctxt, authlist); 543 return 0; 544 } 545 546 /* ARGSUSED */ 547 int 548 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 549 { 550 Authctxt *authctxt = ctxt; 551 Key *key = NULL; 552 Identity *id = NULL; 553 Buffer b; 554 int pktype, sent = 0; 555 u_int alen, blen; 556 char *pkalg, *fp; 557 u_char *pkblob; 558 559 if (authctxt == NULL) 560 fatal("input_userauth_pk_ok: no authentication context"); 561 if (datafellows & SSH_BUG_PKOK) { 562 /* this is similar to SSH_BUG_PKAUTH */ 563 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 564 pkblob = packet_get_string(&blen); 565 buffer_init(&b); 566 buffer_append(&b, pkblob, blen); 567 pkalg = buffer_get_string(&b, &alen); 568 buffer_free(&b); 569 } else { 570 pkalg = packet_get_string(&alen); 571 pkblob = packet_get_string(&blen); 572 } 573 packet_check_eom(); 574 575 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 576 577 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 578 debug("unknown pkalg %s", pkalg); 579 goto done; 580 } 581 if ((key = key_from_blob(pkblob, blen)) == NULL) { 582 debug("no key from blob. pkalg %s", pkalg); 583 goto done; 584 } 585 if (key->type != pktype) { 586 error("input_userauth_pk_ok: type mismatch " 587 "for decoded key (received %d, expected %d)", 588 key->type, pktype); 589 goto done; 590 } 591 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 592 SSH_FP_DEFAULT)) == NULL) 593 goto done; 594 debug2("input_userauth_pk_ok: fp %s", fp); 595 free(fp); 596 597 /* 598 * search keys in the reverse order, because last candidate has been 599 * moved to the end of the queue. this also avoids confusion by 600 * duplicate keys 601 */ 602 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 603 if (key_equal(key, id->key)) { 604 sent = sign_and_send_pubkey(authctxt, id); 605 break; 606 } 607 } 608 done: 609 if (key != NULL) 610 key_free(key); 611 free(pkalg); 612 free(pkblob); 613 614 /* try another method if we did not send a packet */ 615 if (sent == 0) 616 userauth(authctxt, NULL); 617 return 0; 618 } 619 620 #ifdef GSSAPI 621 int 622 userauth_gssapi(Authctxt *authctxt) 623 { 624 Gssctxt *gssctxt = NULL; 625 static gss_OID_set gss_supported = NULL; 626 static u_int mech = 0; 627 OM_uint32 min; 628 int ok = 0; 629 630 /* Try one GSSAPI method at a time, rather than sending them all at 631 * once. */ 632 633 if (gss_supported == NULL) 634 gss_indicate_mechs(&min, &gss_supported); 635 636 /* Check to see if the mechanism is usable before we offer it */ 637 while (mech < gss_supported->count && !ok) { 638 /* My DER encoding requires length<128 */ 639 if (gss_supported->elements[mech].length < 128 && 640 ssh_gssapi_check_mechanism(&gssctxt, 641 &gss_supported->elements[mech], authctxt->host)) { 642 ok = 1; /* Mechanism works */ 643 } else { 644 mech++; 645 } 646 } 647 648 if (!ok) 649 return 0; 650 651 authctxt->methoddata=(void *)gssctxt; 652 653 packet_start(SSH2_MSG_USERAUTH_REQUEST); 654 packet_put_cstring(authctxt->server_user); 655 packet_put_cstring(authctxt->service); 656 packet_put_cstring(authctxt->method->name); 657 658 packet_put_int(1); 659 660 packet_put_int((gss_supported->elements[mech].length) + 2); 661 packet_put_char(SSH_GSS_OIDTYPE); 662 packet_put_char(gss_supported->elements[mech].length); 663 packet_put_raw(gss_supported->elements[mech].elements, 664 gss_supported->elements[mech].length); 665 666 packet_send(); 667 668 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 669 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 670 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 671 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 672 673 mech++; /* Move along to next candidate */ 674 675 return 1; 676 } 677 678 static OM_uint32 679 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 680 { 681 Authctxt *authctxt = ctxt; 682 Gssctxt *gssctxt = authctxt->methoddata; 683 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 684 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 685 gss_buffer_desc gssbuf; 686 OM_uint32 status, ms, flags; 687 Buffer b; 688 689 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 690 recv_tok, &send_tok, &flags); 691 692 if (send_tok.length > 0) { 693 if (GSS_ERROR(status)) 694 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 695 else 696 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 697 698 packet_put_string(send_tok.value, send_tok.length); 699 packet_send(); 700 gss_release_buffer(&ms, &send_tok); 701 } 702 703 if (status == GSS_S_COMPLETE) { 704 /* send either complete or MIC, depending on mechanism */ 705 if (!(flags & GSS_C_INTEG_FLAG)) { 706 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 707 packet_send(); 708 } else { 709 ssh_gssapi_buildmic(&b, authctxt->server_user, 710 authctxt->service, "gssapi-with-mic"); 711 712 gssbuf.value = buffer_ptr(&b); 713 gssbuf.length = buffer_len(&b); 714 715 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 716 717 if (!GSS_ERROR(status)) { 718 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 719 packet_put_string(mic.value, mic.length); 720 721 packet_send(); 722 } 723 724 buffer_free(&b); 725 gss_release_buffer(&ms, &mic); 726 } 727 } 728 729 return status; 730 } 731 732 /* ARGSUSED */ 733 int 734 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 735 { 736 Authctxt *authctxt = ctxt; 737 Gssctxt *gssctxt; 738 int oidlen; 739 char *oidv; 740 741 if (authctxt == NULL) 742 fatal("input_gssapi_response: no authentication context"); 743 gssctxt = authctxt->methoddata; 744 745 /* Setup our OID */ 746 oidv = packet_get_string(&oidlen); 747 748 if (oidlen <= 2 || 749 oidv[0] != SSH_GSS_OIDTYPE || 750 oidv[1] != oidlen - 2) { 751 free(oidv); 752 debug("Badly encoded mechanism OID received"); 753 userauth(authctxt, NULL); 754 return 0; 755 } 756 757 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 758 fatal("Server returned different OID than expected"); 759 760 packet_check_eom(); 761 762 free(oidv); 763 764 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 765 /* Start again with next method on list */ 766 debug("Trying to start again"); 767 userauth(authctxt, NULL); 768 return 0; 769 } 770 return 0; 771 } 772 773 /* ARGSUSED */ 774 int 775 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 776 { 777 Authctxt *authctxt = ctxt; 778 gss_buffer_desc recv_tok; 779 OM_uint32 status; 780 u_int slen; 781 782 if (authctxt == NULL) 783 fatal("input_gssapi_response: no authentication context"); 784 785 recv_tok.value = packet_get_string(&slen); 786 recv_tok.length = slen; /* safe typecast */ 787 788 packet_check_eom(); 789 790 status = process_gssapi_token(ctxt, &recv_tok); 791 792 free(recv_tok.value); 793 794 if (GSS_ERROR(status)) { 795 /* Start again with the next method in the list */ 796 userauth(authctxt, NULL); 797 return 0; 798 } 799 return 0; 800 } 801 802 /* ARGSUSED */ 803 int 804 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 805 { 806 Authctxt *authctxt = ctxt; 807 Gssctxt *gssctxt; 808 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 809 gss_buffer_desc recv_tok; 810 OM_uint32 ms; 811 u_int len; 812 813 if (authctxt == NULL) 814 fatal("input_gssapi_response: no authentication context"); 815 gssctxt = authctxt->methoddata; 816 817 recv_tok.value = packet_get_string(&len); 818 recv_tok.length = len; 819 820 packet_check_eom(); 821 822 /* Stick it into GSSAPI and see what it says */ 823 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 824 &recv_tok, &send_tok, NULL); 825 826 free(recv_tok.value); 827 gss_release_buffer(&ms, &send_tok); 828 829 /* Server will be returning a failed packet after this one */ 830 return 0; 831 } 832 833 /* ARGSUSED */ 834 int 835 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 836 { 837 char *msg; 838 char *lang; 839 840 /* maj */(void)packet_get_int(); 841 /* min */(void)packet_get_int(); 842 msg=packet_get_string(NULL); 843 lang=packet_get_string(NULL); 844 845 packet_check_eom(); 846 847 debug("Server GSSAPI Error:\n%s", msg); 848 free(msg); 849 free(lang); 850 return 0; 851 } 852 #endif /* GSSAPI */ 853 854 int 855 userauth_none(Authctxt *authctxt) 856 { 857 /* initial userauth request */ 858 packet_start(SSH2_MSG_USERAUTH_REQUEST); 859 packet_put_cstring(authctxt->server_user); 860 packet_put_cstring(authctxt->service); 861 packet_put_cstring(authctxt->method->name); 862 packet_send(); 863 return 1; 864 } 865 866 int 867 userauth_passwd(Authctxt *authctxt) 868 { 869 static int attempt = 0; 870 char prompt[150]; 871 char *password; 872 const char *host = options.host_key_alias ? options.host_key_alias : 873 authctxt->host; 874 875 if (attempt++ >= options.number_of_password_prompts) 876 return 0; 877 878 if (attempt != 1) 879 error("Permission denied, please try again."); 880 881 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 882 authctxt->server_user, host); 883 password = read_passphrase(prompt, 0); 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_put_char(0); 889 packet_put_cstring(password); 890 explicit_bzero(password, strlen(password)); 891 free(password); 892 packet_add_padding(64); 893 packet_send(); 894 895 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 896 &input_userauth_passwd_changereq); 897 898 return 1; 899 } 900 901 /* 902 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 903 */ 904 /* ARGSUSED */ 905 int 906 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 907 { 908 Authctxt *authctxt = ctxt; 909 char *info, *lang, *password = NULL, *retype = NULL; 910 char prompt[150]; 911 const char *host = options.host_key_alias ? options.host_key_alias : 912 authctxt->host; 913 914 debug2("input_userauth_passwd_changereq"); 915 916 if (authctxt == NULL) 917 fatal("input_userauth_passwd_changereq: " 918 "no authentication context"); 919 920 info = packet_get_string(NULL); 921 lang = packet_get_string(NULL); 922 if (strlen(info) > 0) 923 logit("%s", info); 924 free(info); 925 free(lang); 926 packet_start(SSH2_MSG_USERAUTH_REQUEST); 927 packet_put_cstring(authctxt->server_user); 928 packet_put_cstring(authctxt->service); 929 packet_put_cstring(authctxt->method->name); 930 packet_put_char(1); /* additional info */ 931 snprintf(prompt, sizeof(prompt), 932 "Enter %.30s@%.128s's old password: ", 933 authctxt->server_user, host); 934 password = read_passphrase(prompt, 0); 935 packet_put_cstring(password); 936 explicit_bzero(password, strlen(password)); 937 free(password); 938 password = NULL; 939 while (password == NULL) { 940 snprintf(prompt, sizeof(prompt), 941 "Enter %.30s@%.128s's new password: ", 942 authctxt->server_user, host); 943 password = read_passphrase(prompt, RP_ALLOW_EOF); 944 if (password == NULL) { 945 /* bail out */ 946 return 0; 947 } 948 snprintf(prompt, sizeof(prompt), 949 "Retype %.30s@%.128s's new password: ", 950 authctxt->server_user, host); 951 retype = read_passphrase(prompt, 0); 952 if (strcmp(password, retype) != 0) { 953 explicit_bzero(password, strlen(password)); 954 free(password); 955 logit("Mismatch; try again, EOF to quit."); 956 password = NULL; 957 } 958 explicit_bzero(retype, strlen(retype)); 959 free(retype); 960 } 961 packet_put_cstring(password); 962 explicit_bzero(password, strlen(password)); 963 free(password); 964 packet_add_padding(64); 965 packet_send(); 966 967 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 968 &input_userauth_passwd_changereq); 969 return 0; 970 } 971 972 static int 973 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 974 const u_char *data, size_t datalen, u_int compat) 975 { 976 Key *prv; 977 int ret; 978 979 /* the agent supports this key */ 980 if (id->agent_fd) 981 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 982 data, datalen, compat); 983 984 /* 985 * we have already loaded the private key or 986 * the private key is stored in external hardware 987 */ 988 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 989 return (sshkey_sign(id->key, sigp, lenp, data, datalen, 990 compat)); 991 /* load the private key from the file */ 992 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 993 return (-1); /* XXX return decent error code */ 994 ret = sshkey_sign(prv, sigp, lenp, data, datalen, compat); 995 sshkey_free(prv); 996 return (ret); 997 } 998 999 static int 1000 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1001 { 1002 Buffer b; 1003 u_char *blob, *signature; 1004 u_int bloblen; 1005 size_t slen; 1006 u_int skip = 0; 1007 int ret = -1; 1008 int have_sig = 1; 1009 char *fp; 1010 1011 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1012 SSH_FP_DEFAULT)) == NULL) 1013 return 0; 1014 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1015 free(fp); 1016 1017 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1018 /* we cannot handle this key */ 1019 debug3("sign_and_send_pubkey: cannot handle key"); 1020 return 0; 1021 } 1022 /* data to be signed */ 1023 buffer_init(&b); 1024 if (datafellows & SSH_OLD_SESSIONID) { 1025 buffer_append(&b, session_id2, session_id2_len); 1026 skip = session_id2_len; 1027 } else { 1028 buffer_put_string(&b, session_id2, session_id2_len); 1029 skip = buffer_len(&b); 1030 } 1031 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1032 buffer_put_cstring(&b, authctxt->server_user); 1033 buffer_put_cstring(&b, 1034 datafellows & SSH_BUG_PKSERVICE ? 1035 "ssh-userauth" : 1036 authctxt->service); 1037 if (datafellows & SSH_BUG_PKAUTH) { 1038 buffer_put_char(&b, have_sig); 1039 } else { 1040 buffer_put_cstring(&b, authctxt->method->name); 1041 buffer_put_char(&b, have_sig); 1042 buffer_put_cstring(&b, key_ssh_name(id->key)); 1043 } 1044 buffer_put_string(&b, blob, bloblen); 1045 1046 /* generate signature */ 1047 ret = identity_sign(id, &signature, &slen, 1048 buffer_ptr(&b), buffer_len(&b), datafellows); 1049 if (ret != 0) { 1050 free(blob); 1051 buffer_free(&b); 1052 return 0; 1053 } 1054 #ifdef DEBUG_PK 1055 buffer_dump(&b); 1056 #endif 1057 if (datafellows & SSH_BUG_PKSERVICE) { 1058 buffer_clear(&b); 1059 buffer_append(&b, session_id2, session_id2_len); 1060 skip = session_id2_len; 1061 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1062 buffer_put_cstring(&b, authctxt->server_user); 1063 buffer_put_cstring(&b, authctxt->service); 1064 buffer_put_cstring(&b, authctxt->method->name); 1065 buffer_put_char(&b, have_sig); 1066 if (!(datafellows & SSH_BUG_PKAUTH)) 1067 buffer_put_cstring(&b, key_ssh_name(id->key)); 1068 buffer_put_string(&b, blob, bloblen); 1069 } 1070 free(blob); 1071 1072 /* append signature */ 1073 buffer_put_string(&b, signature, slen); 1074 free(signature); 1075 1076 /* skip session id and packet type */ 1077 if (buffer_len(&b) < skip + 1) 1078 fatal("userauth_pubkey: internal error"); 1079 buffer_consume(&b, skip + 1); 1080 1081 /* put remaining data from buffer into packet */ 1082 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1083 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1084 buffer_free(&b); 1085 packet_send(); 1086 1087 return 1; 1088 } 1089 1090 static int 1091 send_pubkey_test(Authctxt *authctxt, Identity *id) 1092 { 1093 u_char *blob; 1094 u_int bloblen, have_sig = 0; 1095 1096 debug3("send_pubkey_test"); 1097 1098 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1099 /* we cannot handle this key */ 1100 debug3("send_pubkey_test: cannot handle key"); 1101 return 0; 1102 } 1103 /* register callback for USERAUTH_PK_OK message */ 1104 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1105 1106 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1107 packet_put_cstring(authctxt->server_user); 1108 packet_put_cstring(authctxt->service); 1109 packet_put_cstring(authctxt->method->name); 1110 packet_put_char(have_sig); 1111 if (!(datafellows & SSH_BUG_PKAUTH)) 1112 packet_put_cstring(key_ssh_name(id->key)); 1113 packet_put_string(blob, bloblen); 1114 free(blob); 1115 packet_send(); 1116 return 1; 1117 } 1118 1119 static Key * 1120 load_identity_file(char *filename, int userprovided) 1121 { 1122 Key *private; 1123 char prompt[300], *passphrase; 1124 int r, perm_ok = 0, quit = 0, i; 1125 struct stat st; 1126 1127 if (stat(filename, &st) < 0) { 1128 (userprovided ? logit : debug3)("no such identity: %s: %s", 1129 filename, strerror(errno)); 1130 return NULL; 1131 } 1132 snprintf(prompt, sizeof prompt, 1133 "Enter passphrase for key '%.100s': ", filename); 1134 for (i = 0; i <= options.number_of_password_prompts; i++) { 1135 if (i == 0) 1136 passphrase = ""; 1137 else { 1138 passphrase = read_passphrase(prompt, 0); 1139 if (*passphrase == '\0') { 1140 debug2("no passphrase given, try next key"); 1141 free(passphrase); 1142 break; 1143 } 1144 } 1145 switch ((r = sshkey_load_private_type(KEY_UNSPEC, filename, 1146 passphrase, &private, NULL, &perm_ok))) { 1147 case 0: 1148 break; 1149 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1150 if (options.batch_mode) { 1151 quit = 1; 1152 break; 1153 } 1154 if (i != 0) 1155 debug2("bad passphrase given, try again..."); 1156 break; 1157 case SSH_ERR_SYSTEM_ERROR: 1158 if (errno == ENOENT) { 1159 debug2("Load key \"%s\": %s", 1160 filename, ssh_err(r)); 1161 quit = 1; 1162 break; 1163 } 1164 /* FALLTHROUGH */ 1165 default: 1166 error("Load key \"%s\": %s", filename, ssh_err(r)); 1167 quit = 1; 1168 break; 1169 } 1170 if (i > 0) { 1171 explicit_bzero(passphrase, strlen(passphrase)); 1172 free(passphrase); 1173 } 1174 if (private != NULL || quit) 1175 break; 1176 } 1177 return private; 1178 } 1179 1180 /* 1181 * try keys in the following order: 1182 * 1. agent keys that are found in the config file 1183 * 2. other agent keys 1184 * 3. keys that are only listed in the config file 1185 */ 1186 static void 1187 pubkey_prepare(Authctxt *authctxt) 1188 { 1189 struct identity *id, *id2, *tmp; 1190 struct idlist agent, files, *preferred; 1191 struct sshkey *key; 1192 int agent_fd, i, r, found; 1193 size_t j; 1194 struct ssh_identitylist *idlist; 1195 1196 TAILQ_INIT(&agent); /* keys from the agent */ 1197 TAILQ_INIT(&files); /* keys from the config file */ 1198 preferred = &authctxt->keys; 1199 TAILQ_INIT(preferred); /* preferred order of keys */ 1200 1201 /* list of keys stored in the filesystem and PKCS#11 */ 1202 for (i = 0; i < options.num_identity_files; i++) { 1203 key = options.identity_keys[i]; 1204 if (key && key->type == KEY_RSA1) 1205 continue; 1206 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1207 continue; 1208 options.identity_keys[i] = NULL; 1209 id = xcalloc(1, sizeof(*id)); 1210 id->key = key; 1211 id->filename = xstrdup(options.identity_files[i]); 1212 id->userprovided = options.identity_file_userprovided[i]; 1213 TAILQ_INSERT_TAIL(&files, id, next); 1214 } 1215 /* Prefer PKCS11 keys that are explicitly listed */ 1216 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1217 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1218 continue; 1219 found = 0; 1220 TAILQ_FOREACH(id2, &files, next) { 1221 if (id2->key == NULL || 1222 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1223 continue; 1224 if (sshkey_equal(id->key, id2->key)) { 1225 TAILQ_REMOVE(&files, id, next); 1226 TAILQ_INSERT_TAIL(preferred, id, next); 1227 found = 1; 1228 break; 1229 } 1230 } 1231 /* If IdentitiesOnly set and key not found then don't use it */ 1232 if (!found && options.identities_only) { 1233 TAILQ_REMOVE(&files, id, next); 1234 explicit_bzero(id, sizeof(*id)); 1235 free(id); 1236 } 1237 } 1238 /* list of keys supported by the agent */ 1239 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1240 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1241 debug("%s: ssh_get_authentication_socket: %s", 1242 __func__, ssh_err(r)); 1243 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) { 1244 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1245 debug("%s: ssh_fetch_identitylist: %s", 1246 __func__, ssh_err(r)); 1247 } else { 1248 for (j = 0; j < idlist->nkeys; j++) { 1249 found = 0; 1250 TAILQ_FOREACH(id, &files, next) { 1251 /* 1252 * agent keys from the config file are 1253 * preferred 1254 */ 1255 if (sshkey_equal(idlist->keys[j], id->key)) { 1256 TAILQ_REMOVE(&files, id, next); 1257 TAILQ_INSERT_TAIL(preferred, id, next); 1258 id->agent_fd = agent_fd; 1259 found = 1; 1260 break; 1261 } 1262 } 1263 if (!found && !options.identities_only) { 1264 id = xcalloc(1, sizeof(*id)); 1265 /* XXX "steals" key/comment from idlist */ 1266 id->key = idlist->keys[j]; 1267 id->filename = idlist->comments[j]; 1268 idlist->keys[j] = NULL; 1269 idlist->comments[j] = NULL; 1270 id->agent_fd = agent_fd; 1271 TAILQ_INSERT_TAIL(&agent, id, next); 1272 } 1273 } 1274 ssh_free_identitylist(idlist); 1275 /* append remaining agent keys */ 1276 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1277 TAILQ_REMOVE(&agent, id, next); 1278 TAILQ_INSERT_TAIL(preferred, id, next); 1279 } 1280 authctxt->agent_fd = agent_fd; 1281 } 1282 /* append remaining keys from the config file */ 1283 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1284 TAILQ_REMOVE(&files, id, next); 1285 TAILQ_INSERT_TAIL(preferred, id, next); 1286 } 1287 TAILQ_FOREACH(id, preferred, next) { 1288 debug2("key: %s (%p),%s", id->filename, id->key, 1289 id->userprovided ? " explicit" : ""); 1290 } 1291 } 1292 1293 static void 1294 pubkey_cleanup(Authctxt *authctxt) 1295 { 1296 Identity *id; 1297 1298 if (authctxt->agent_fd != -1) 1299 ssh_close_authentication_socket(authctxt->agent_fd); 1300 for (id = TAILQ_FIRST(&authctxt->keys); id; 1301 id = TAILQ_FIRST(&authctxt->keys)) { 1302 TAILQ_REMOVE(&authctxt->keys, id, next); 1303 if (id->key) 1304 sshkey_free(id->key); 1305 free(id->filename); 1306 free(id); 1307 } 1308 } 1309 1310 int 1311 userauth_pubkey(Authctxt *authctxt) 1312 { 1313 Identity *id; 1314 int sent = 0; 1315 1316 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1317 if (id->tried++) 1318 return (0); 1319 /* move key to the end of the queue */ 1320 TAILQ_REMOVE(&authctxt->keys, id, next); 1321 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1322 /* 1323 * send a test message if we have the public key. for 1324 * encrypted keys we cannot do this and have to load the 1325 * private key instead 1326 */ 1327 if (id->key != NULL) { 1328 if (key_type_plain(id->key->type) == KEY_RSA && 1329 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1330 debug("Skipped %s key %s for RSA/MD5 server", 1331 key_type(id->key), id->filename); 1332 } else if (id->key->type != KEY_RSA1) { 1333 debug("Offering %s public key: %s", 1334 key_type(id->key), id->filename); 1335 sent = send_pubkey_test(authctxt, id); 1336 } 1337 } else { 1338 debug("Trying private key: %s", id->filename); 1339 id->key = load_identity_file(id->filename, 1340 id->userprovided); 1341 if (id->key != NULL) { 1342 id->isprivate = 1; 1343 if (key_type_plain(id->key->type) == KEY_RSA && 1344 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1345 debug("Skipped %s key %s for RSA/MD5 " 1346 "server", key_type(id->key), 1347 id->filename); 1348 } else { 1349 sent = sign_and_send_pubkey( 1350 authctxt, id); 1351 } 1352 key_free(id->key); 1353 id->key = NULL; 1354 } 1355 } 1356 if (sent) 1357 return (sent); 1358 } 1359 return (0); 1360 } 1361 1362 /* 1363 * Send userauth request message specifying keyboard-interactive method. 1364 */ 1365 int 1366 userauth_kbdint(Authctxt *authctxt) 1367 { 1368 static int attempt = 0; 1369 1370 if (attempt++ >= options.number_of_password_prompts) 1371 return 0; 1372 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1373 if (attempt > 1 && !authctxt->info_req_seen) { 1374 debug3("userauth_kbdint: disable: no info_req_seen"); 1375 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1376 return 0; 1377 } 1378 1379 debug2("userauth_kbdint"); 1380 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1381 packet_put_cstring(authctxt->server_user); 1382 packet_put_cstring(authctxt->service); 1383 packet_put_cstring(authctxt->method->name); 1384 packet_put_cstring(""); /* lang */ 1385 packet_put_cstring(options.kbd_interactive_devices ? 1386 options.kbd_interactive_devices : ""); 1387 packet_send(); 1388 1389 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1390 return 1; 1391 } 1392 1393 /* 1394 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1395 */ 1396 int 1397 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1398 { 1399 Authctxt *authctxt = ctxt; 1400 char *name, *inst, *lang, *prompt, *response; 1401 u_int num_prompts, i; 1402 int echo = 0; 1403 1404 debug2("input_userauth_info_req"); 1405 1406 if (authctxt == NULL) 1407 fatal("input_userauth_info_req: no authentication context"); 1408 1409 authctxt->info_req_seen = 1; 1410 1411 name = packet_get_string(NULL); 1412 inst = packet_get_string(NULL); 1413 lang = packet_get_string(NULL); 1414 if (strlen(name) > 0) 1415 logit("%s", name); 1416 if (strlen(inst) > 0) 1417 logit("%s", inst); 1418 free(name); 1419 free(inst); 1420 free(lang); 1421 1422 num_prompts = packet_get_int(); 1423 /* 1424 * Begin to build info response packet based on prompts requested. 1425 * We commit to providing the correct number of responses, so if 1426 * further on we run into a problem that prevents this, we have to 1427 * be sure and clean this up and send a correct error response. 1428 */ 1429 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1430 packet_put_int(num_prompts); 1431 1432 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1433 for (i = 0; i < num_prompts; i++) { 1434 prompt = packet_get_string(NULL); 1435 echo = packet_get_char(); 1436 1437 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1438 1439 packet_put_cstring(response); 1440 explicit_bzero(response, strlen(response)); 1441 free(response); 1442 free(prompt); 1443 } 1444 packet_check_eom(); /* done with parsing incoming message. */ 1445 1446 packet_add_padding(64); 1447 packet_send(); 1448 return 0; 1449 } 1450 1451 static int 1452 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1453 const u_char *data, size_t datalen) 1454 { 1455 struct sshbuf *b; 1456 struct stat st; 1457 pid_t pid; 1458 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1459 u_char rversion = 0, version = 2; 1460 void (*osigchld)(int); 1461 1462 *sigp = NULL; 1463 *lenp = 0; 1464 1465 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1466 error("%s: not installed: %s", __func__, strerror(errno)); 1467 return -1; 1468 } 1469 if (fflush(stdout) != 0) { 1470 error("%s: fflush: %s", __func__, strerror(errno)); 1471 return -1; 1472 } 1473 if (pipe(to) < 0) { 1474 error("%s: pipe: %s", __func__, strerror(errno)); 1475 return -1; 1476 } 1477 if (pipe(from) < 0) { 1478 error("%s: pipe: %s", __func__, strerror(errno)); 1479 return -1; 1480 } 1481 if ((pid = fork()) < 0) { 1482 error("%s: fork: %s", __func__, strerror(errno)); 1483 return -1; 1484 } 1485 osigchld = signal(SIGCHLD, SIG_DFL); 1486 if (pid == 0) { 1487 /* keep the socket on exec */ 1488 fcntl(sock, F_SETFD, 0); 1489 permanently_drop_suid(getuid()); 1490 close(from[0]); 1491 if (dup2(from[1], STDOUT_FILENO) < 0) 1492 fatal("%s: dup2: %s", __func__, strerror(errno)); 1493 close(to[1]); 1494 if (dup2(to[0], STDIN_FILENO) < 0) 1495 fatal("%s: dup2: %s", __func__, strerror(errno)); 1496 close(from[1]); 1497 close(to[0]); 1498 /* Close everything but stdio and the socket */ 1499 for (i = STDERR_FILENO + 1; i < sock; i++) 1500 close(i); 1501 closefrom(sock + 1); 1502 debug3("%s: [child] pid=%ld, exec %s", 1503 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1504 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1505 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1506 strerror(errno)); 1507 } 1508 close(from[1]); 1509 close(to[0]); 1510 1511 if ((b = sshbuf_new()) == NULL) 1512 fatal("%s: sshbuf_new failed", __func__); 1513 /* send # of sock, data to be signed */ 1514 if ((r = sshbuf_put_u32(b, sock) != 0) || 1515 (r = sshbuf_put_string(b, data, datalen)) != 0) 1516 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1517 if (ssh_msg_send(to[1], version, b) == -1) 1518 fatal("%s: couldn't send request", __func__); 1519 sshbuf_reset(b); 1520 r = ssh_msg_recv(from[0], b); 1521 close(from[0]); 1522 close(to[1]); 1523 if (r < 0) { 1524 error("%s: no reply", __func__); 1525 goto fail; 1526 } 1527 1528 errno = 0; 1529 while (waitpid(pid, &status, 0) < 0) { 1530 if (errno != EINTR) { 1531 error("%s: waitpid %ld: %s", 1532 __func__, (long)pid, strerror(errno)); 1533 goto fail; 1534 } 1535 } 1536 if (!WIFEXITED(status)) { 1537 error("%s: exited abnormally", __func__); 1538 goto fail; 1539 } 1540 if (WEXITSTATUS(status) != 0) { 1541 error("%s: exited with status %d", 1542 __func__, WEXITSTATUS(status)); 1543 goto fail; 1544 } 1545 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1546 error("%s: buffer error: %s", __func__, ssh_err(r)); 1547 goto fail; 1548 } 1549 if (rversion != version) { 1550 error("%s: bad version", __func__); 1551 goto fail; 1552 } 1553 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1554 error("%s: buffer error: %s", __func__, ssh_err(r)); 1555 fail: 1556 signal(SIGCHLD, osigchld); 1557 sshbuf_free(b); 1558 return -1; 1559 } 1560 signal(SIGCHLD, osigchld); 1561 sshbuf_free(b); 1562 1563 return 0; 1564 } 1565 1566 int 1567 userauth_hostbased(Authctxt *authctxt) 1568 { 1569 struct ssh *ssh = active_state; 1570 struct sshkey *private = NULL; 1571 struct sshbuf *b = NULL; 1572 const char *service; 1573 u_char *sig = NULL, *keyblob = NULL; 1574 char *fp = NULL, *chost = NULL, *lname = NULL; 1575 size_t siglen = 0, keylen = 0; 1576 int i, r, success = 0; 1577 1578 if (authctxt->ktypes == NULL) { 1579 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1580 authctxt->ktypes = authctxt->oktypes; 1581 } 1582 1583 /* 1584 * Work through each listed type pattern in HostbasedKeyTypes, 1585 * trying each hostkey that matches the type in turn. 1586 */ 1587 for (;;) { 1588 if (authctxt->active_ktype == NULL) 1589 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1590 if (authctxt->active_ktype == NULL || 1591 *authctxt->active_ktype == '\0') 1592 break; 1593 debug3("%s: trying key type %s", __func__, 1594 authctxt->active_ktype); 1595 1596 /* check for a useful key */ 1597 private = NULL; 1598 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1599 if (authctxt->sensitive->keys[i] == NULL || 1600 authctxt->sensitive->keys[i]->type == KEY_RSA1 || 1601 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1602 continue; 1603 if (match_pattern_list( 1604 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1605 authctxt->active_ktype, 1606 strlen(authctxt->active_ktype), 0) != 1) 1607 continue; 1608 /* we take and free the key */ 1609 private = authctxt->sensitive->keys[i]; 1610 authctxt->sensitive->keys[i] = NULL; 1611 break; 1612 } 1613 /* Found one */ 1614 if (private != NULL) 1615 break; 1616 /* No more keys of this type; advance */ 1617 authctxt->active_ktype = NULL; 1618 } 1619 if (private == NULL) { 1620 free(authctxt->oktypes); 1621 authctxt->oktypes = authctxt->ktypes = NULL; 1622 authctxt->active_ktype = NULL; 1623 debug("No more client hostkeys for hostbased authentication."); 1624 goto out; 1625 } 1626 1627 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1628 SSH_FP_DEFAULT)) == NULL) { 1629 error("%s: sshkey_fingerprint failed", __func__); 1630 goto out; 1631 } 1632 debug("%s: trying hostkey %s %s", 1633 __func__, sshkey_ssh_name(private), fp); 1634 1635 /* figure out a name for the client host */ 1636 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1637 error("%s: cannot get local ipaddr/name", __func__); 1638 goto out; 1639 } 1640 1641 /* XXX sshbuf_put_stringf? */ 1642 xasprintf(&chost, "%s.", lname); 1643 debug2("%s: chost %s", __func__, chost); 1644 1645 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1646 authctxt->service; 1647 1648 /* construct data */ 1649 if ((b = sshbuf_new()) == NULL) { 1650 error("%s: sshbuf_new failed", __func__); 1651 goto out; 1652 } 1653 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1654 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1655 goto out; 1656 } 1657 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1658 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1659 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1660 (r = sshbuf_put_cstring(b, service)) != 0 || 1661 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1662 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1663 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1664 (r = sshbuf_put_cstring(b, chost)) != 0 || 1665 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1666 error("%s: buffer error: %s", __func__, ssh_err(r)); 1667 goto out; 1668 } 1669 1670 #ifdef DEBUG_PK 1671 sshbuf_dump(b, stderr); 1672 #endif 1673 if (authctxt->sensitive->external_keysign) 1674 r = ssh_keysign(private, &sig, &siglen, 1675 sshbuf_ptr(b), sshbuf_len(b)); 1676 else if ((r = sshkey_sign(private, &sig, &siglen, 1677 sshbuf_ptr(b), sshbuf_len(b), datafellows)) != 0) 1678 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1679 if (r != 0) { 1680 error("sign using hostkey %s %s failed", 1681 sshkey_ssh_name(private), fp); 1682 goto out; 1683 } 1684 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1685 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1686 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1687 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1688 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1689 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1690 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1691 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1692 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1693 (r = sshpkt_send(ssh)) != 0) { 1694 error("%s: packet error: %s", __func__, ssh_err(r)); 1695 goto out; 1696 } 1697 success = 1; 1698 1699 out: 1700 if (sig != NULL) { 1701 explicit_bzero(sig, siglen); 1702 free(sig); 1703 } 1704 free(keyblob); 1705 free(lname); 1706 free(fp); 1707 free(chost); 1708 sshkey_free(private); 1709 sshbuf_free(b); 1710 1711 return success; 1712 } 1713 1714 /* find auth method */ 1715 1716 /* 1717 * given auth method name, if configurable options permit this method fill 1718 * in auth_ident field and return true, otherwise return false. 1719 */ 1720 static int 1721 authmethod_is_enabled(Authmethod *method) 1722 { 1723 if (method == NULL) 1724 return 0; 1725 /* return false if options indicate this method is disabled */ 1726 if (method->enabled == NULL || *method->enabled == 0) 1727 return 0; 1728 /* return false if batch mode is enabled but method needs interactive mode */ 1729 if (method->batch_flag != NULL && *method->batch_flag != 0) 1730 return 0; 1731 return 1; 1732 } 1733 1734 static Authmethod * 1735 authmethod_lookup(const char *name) 1736 { 1737 Authmethod *method = NULL; 1738 if (name != NULL) 1739 for (method = authmethods; method->name != NULL; method++) 1740 if (strcmp(name, method->name) == 0) 1741 return method; 1742 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1743 return NULL; 1744 } 1745 1746 /* XXX internal state */ 1747 static Authmethod *current = NULL; 1748 static char *supported = NULL; 1749 static char *preferred = NULL; 1750 1751 /* 1752 * Given the authentication method list sent by the server, return the 1753 * next method we should try. If the server initially sends a nil list, 1754 * use a built-in default list. 1755 */ 1756 static Authmethod * 1757 authmethod_get(char *authlist) 1758 { 1759 char *name = NULL; 1760 u_int next; 1761 1762 /* Use a suitable default if we're passed a nil list. */ 1763 if (authlist == NULL || strlen(authlist) == 0) 1764 authlist = options.preferred_authentications; 1765 1766 if (supported == NULL || strcmp(authlist, supported) != 0) { 1767 debug3("start over, passed a different list %s", authlist); 1768 free(supported); 1769 supported = xstrdup(authlist); 1770 preferred = options.preferred_authentications; 1771 debug3("preferred %s", preferred); 1772 current = NULL; 1773 } else if (current != NULL && authmethod_is_enabled(current)) 1774 return current; 1775 1776 for (;;) { 1777 if ((name = match_list(preferred, supported, &next)) == NULL) { 1778 debug("No more authentication methods to try."); 1779 current = NULL; 1780 return NULL; 1781 } 1782 preferred += next; 1783 debug3("authmethod_lookup %s", name); 1784 debug3("remaining preferred: %s", preferred); 1785 if ((current = authmethod_lookup(name)) != NULL && 1786 authmethod_is_enabled(current)) { 1787 debug3("authmethod_is_enabled %s", name); 1788 debug("Next authentication method: %s", name); 1789 free(name); 1790 return current; 1791 } 1792 free(name); 1793 } 1794 } 1795 1796 static char * 1797 authmethods_get(void) 1798 { 1799 Authmethod *method = NULL; 1800 Buffer b; 1801 char *list; 1802 1803 buffer_init(&b); 1804 for (method = authmethods; method->name != NULL; method++) { 1805 if (authmethod_is_enabled(method)) { 1806 if (buffer_len(&b) > 0) 1807 buffer_append(&b, ",", 1); 1808 buffer_append(&b, method->name, strlen(method->name)); 1809 } 1810 } 1811 buffer_append(&b, "\0", 1); 1812 list = xstrdup(buffer_ptr(&b)); 1813 buffer_free(&b); 1814 return list; 1815 } 1816 1817
Indexes created Fri Mar 06 19:51:54 UTC 2026