1 /* $NetBSD: sshconnect2.c,v 1.13 2013/04/29 17:59:50 mlelstv Exp $ */ 2 /* $OpenBSD: sshconnect2.c,v 1.192 2013/02/17 23:16:57 dtucker Exp $ */ 3 /* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * Copyright (c) 2008 Damien Miller. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: sshconnect2.c,v 1.13 2013/04/29 17:59:50 mlelstv Exp $"); 30 #include <sys/types.h> 31 #include <sys/socket.h> 32 #include <sys/wait.h> 33 #include <sys/queue.h> 34 #include <sys/stat.h> 35 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <netdb.h> 39 #include <stdio.h> 40 #include <string.h> 41 #include <signal.h> 42 #include <pwd.h> 43 #include <unistd.h> 44 #include <vis.h> 45 46 #ifdef KRB5 47 #include <krb5.h> 48 #endif 49 50 #include "xmalloc.h" 51 #include "ssh.h" 52 #include "ssh2.h" 53 #include "buffer.h" 54 #include "packet.h" 55 #include "compat.h" 56 #include "cipher.h" 57 #include "key.h" 58 #include "kex.h" 59 #include "myproposal.h" 60 #include "sshconnect.h" 61 #include "authfile.h" 62 #include "dh.h" 63 #include "authfd.h" 64 #include "log.h" 65 #include "readconf.h" 66 #include "misc.h" 67 #include "match.h" 68 #include "dispatch.h" 69 #include "canohost.h" 70 #include "msg.h" 71 #include "pathnames.h" 72 #include "uidswap.h" 73 #include "hostfile.h" 74 #include "schnorr.h" 75 #include "jpake.h" 76 77 #ifdef GSSAPI 78 #include "ssh-gss.h" 79 #endif 80 81 /* import */ 82 extern char *client_version_string; 83 extern char *server_version_string; 84 extern Options options; 85 extern Kex *xxx_kex; 86 87 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */ 88 /* if it is set then prevent the switch to the null cipher */ 89 90 extern int tty_flag; 91 92 /* 93 * SSH2 key exchange 94 */ 95 96 u_char *session_id2 = NULL; 97 u_int session_id2_len = 0; 98 99 char *xxx_host; 100 struct sockaddr *xxx_hostaddr; 101 102 Kex *xxx_kex = NULL; 103 104 static int 105 verify_host_key_callback(Key *hostkey) 106 { 107 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 108 fatal("Host key verification failed."); 109 return 0; 110 } 111 112 static char * 113 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 114 { 115 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 116 size_t maxlen; 117 struct hostkeys *hostkeys; 118 int ktype; 119 u_int i; 120 121 /* Find all hostkeys for this hostname */ 122 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 123 hostkeys = init_hostkeys(); 124 for (i = 0; i < options.num_user_hostfiles; i++) 125 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 126 for (i = 0; i < options.num_system_hostfiles; i++) 127 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 128 129 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 130 maxlen = strlen(avail) + 1; 131 first = xmalloc(maxlen); 132 last = xmalloc(maxlen); 133 *first = *last = '\0'; 134 135 #define ALG_APPEND(to, from) \ 136 do { \ 137 if (*to != '\0') \ 138 strlcat(to, ",", maxlen); \ 139 strlcat(to, from, maxlen); \ 140 } while (0) 141 142 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 143 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 144 fatal("%s: unknown alg %s", __func__, alg); 145 if (lookup_key_in_hostkeys_by_type(hostkeys, 146 key_type_plain(ktype), NULL)) 147 ALG_APPEND(first, alg); 148 else 149 ALG_APPEND(last, alg); 150 } 151 #undef ALG_APPEND 152 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 153 if (*first != '\0') 154 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 155 156 xfree(first); 157 xfree(last); 158 xfree(hostname); 159 xfree(oavail); 160 free_hostkeys(hostkeys); 161 162 return ret; 163 } 164 165 void 166 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 167 { 168 Kex *kex; 169 170 xxx_host = host; 171 xxx_hostaddr = hostaddr; 172 173 if (options.ciphers == (char *)-1) { 174 logit("No valid ciphers for protocol version 2 given, using defaults."); 175 options.ciphers = NULL; 176 } 177 if (options.ciphers != NULL) { 178 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 179 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 180 } 181 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 182 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 183 myproposal[PROPOSAL_ENC_ALGS_STOC] = 184 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 185 if (options.compression) { 186 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 187 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 188 } else { 189 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 190 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 191 } 192 if (options.macs != NULL) { 193 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 194 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 195 } 196 if (options.hostkeyalgorithms != NULL) 197 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 198 options.hostkeyalgorithms; 199 else { 200 /* Prefer algorithms that we already have keys for */ 201 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 202 order_hostkeyalgs(host, hostaddr, port); 203 } 204 if (options.kex_algorithms != NULL) 205 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 206 207 if (options.rekey_limit) 208 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 209 210 /* start key exchange */ 211 kex = kex_setup(myproposal); 212 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 213 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 214 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 215 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 216 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 217 kex->client_version_string=client_version_string; 218 kex->server_version_string=server_version_string; 219 kex->verify_host_key=&verify_host_key_callback; 220 221 xxx_kex = kex; 222 223 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 224 225 if (options.use_roaming && !kex->roaming) { 226 debug("Roaming not allowed by server"); 227 options.use_roaming = 0; 228 } 229 230 session_id2 = kex->session_id; 231 session_id2_len = kex->session_id_len; 232 233 #ifdef DEBUG_KEXDH 234 /* send 1st encrypted/maced/compressed message */ 235 packet_start(SSH2_MSG_IGNORE); 236 packet_put_cstring("markus"); 237 packet_send(); 238 packet_write_wait(); 239 #endif 240 } 241 242 /* 243 * Authenticate user 244 */ 245 246 typedef struct Authctxt Authctxt; 247 typedef struct Authmethod Authmethod; 248 typedef struct identity Identity; 249 typedef struct idlist Idlist; 250 251 struct identity { 252 TAILQ_ENTRY(identity) next; 253 AuthenticationConnection *ac; /* set if agent supports key */ 254 Key *key; /* public/private key */ 255 char *filename; /* comment for agent-only keys */ 256 int tried; 257 int isprivate; /* key points to the private key */ 258 int userprovided; 259 }; 260 TAILQ_HEAD(idlist, identity); 261 262 struct Authctxt { 263 const char *server_user; 264 const char *local_user; 265 const char *host; 266 const char *service; 267 Authmethod *method; 268 sig_atomic_t success; 269 char *authlist; 270 /* pubkey */ 271 Idlist keys; 272 AuthenticationConnection *agent; 273 /* hostbased */ 274 Sensitive *sensitive; 275 /* kbd-interactive */ 276 int info_req_seen; 277 /* generic */ 278 void *methoddata; 279 }; 280 struct Authmethod { 281 const char *name; /* string to compare against server's list */ 282 int (*userauth)(Authctxt *authctxt); 283 void (*cleanup)(Authctxt *authctxt); 284 int *enabled; /* flag in option struct that enables method */ 285 int *batch_flag; /* flag in option struct that disables method */ 286 }; 287 288 void input_userauth_success(int, u_int32_t, void *); 289 __dead void input_userauth_success_unexpected(int, u_int32_t, void *); 290 void input_userauth_failure(int, u_int32_t, void *); 291 void input_userauth_banner(int, u_int32_t, void *); 292 __dead void input_userauth_error(int, u_int32_t, void *); 293 void input_userauth_info_req(int, u_int32_t, void *); 294 void input_userauth_pk_ok(int, u_int32_t, void *); 295 void input_userauth_passwd_changereq(int, u_int32_t, void *); 296 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 297 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 298 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 299 300 int userauth_none(Authctxt *); 301 int userauth_pubkey(Authctxt *); 302 int userauth_passwd(Authctxt *); 303 int userauth_kbdint(Authctxt *); 304 int userauth_hostbased(Authctxt *); 305 int userauth_kerberos(Authctxt *); 306 int userauth_jpake(Authctxt *); 307 308 void userauth_jpake_cleanup(Authctxt *); 309 310 #ifdef GSSAPI 311 int userauth_gssapi(Authctxt *authctxt); 312 void input_gssapi_response(int type, u_int32_t, void *); 313 void input_gssapi_token(int type, u_int32_t, void *); 314 void input_gssapi_hash(int type, u_int32_t, void *); 315 void input_gssapi_error(int, u_int32_t, void *); 316 void input_gssapi_errtok(int, u_int32_t, void *); 317 #endif 318 319 void userauth(Authctxt *, char *); 320 321 static int sign_and_send_pubkey(Authctxt *, Identity *); 322 static void pubkey_prepare(Authctxt *); 323 static void pubkey_cleanup(Authctxt *); 324 static Key *load_identity_file(char *, int); 325 326 static Authmethod *authmethod_get(char *authlist); 327 static Authmethod *authmethod_lookup(const char *name); 328 static char *authmethods_get(void); 329 330 Authmethod authmethods[] = { 331 #ifdef GSSAPI 332 {"gssapi-with-mic", 333 userauth_gssapi, 334 NULL, 335 &options.gss_authentication, 336 NULL}, 337 #endif 338 {"hostbased", 339 userauth_hostbased, 340 NULL, 341 &options.hostbased_authentication, 342 NULL}, 343 #if KRB5 344 {"kerberos-2@ssh.com", 345 userauth_kerberos, 346 NULL, 347 &options.kerberos_authentication, 348 NULL}, 349 #endif 350 {"publickey", 351 userauth_pubkey, 352 NULL, 353 &options.pubkey_authentication, 354 NULL}, 355 #ifdef JPAKE 356 {"jpake-01@openssh.com", 357 userauth_jpake, 358 userauth_jpake_cleanup, 359 &options.zero_knowledge_password_authentication, 360 &options.batch_mode}, 361 #endif 362 {"keyboard-interactive", 363 userauth_kbdint, 364 NULL, 365 &options.kbd_interactive_authentication, 366 &options.batch_mode}, 367 {"password", 368 userauth_passwd, 369 NULL, 370 &options.password_authentication, 371 &options.batch_mode}, 372 {"none", 373 userauth_none, 374 NULL, 375 NULL, 376 NULL}, 377 {NULL, NULL, NULL, NULL, NULL} 378 }; 379 380 void 381 ssh_userauth2(const char *local_user, const char *server_user, char *host, 382 Sensitive *sensitive) 383 { 384 Authctxt authctxt; 385 int type; 386 387 if (options.challenge_response_authentication) 388 options.kbd_interactive_authentication = 1; 389 390 packet_start(SSH2_MSG_SERVICE_REQUEST); 391 packet_put_cstring("ssh-userauth"); 392 packet_send(); 393 debug("SSH2_MSG_SERVICE_REQUEST sent"); 394 packet_write_wait(); 395 type = packet_read(); 396 if (type != SSH2_MSG_SERVICE_ACCEPT) 397 fatal("Server denied authentication request: %d", type); 398 if (packet_remaining() > 0) { 399 char *reply = packet_get_string(NULL); 400 debug2("service_accept: %s", reply); 401 xfree(reply); 402 } else { 403 debug2("buggy server: service_accept w/o service"); 404 } 405 packet_check_eom(); 406 debug("SSH2_MSG_SERVICE_ACCEPT received"); 407 408 if (options.preferred_authentications == NULL) 409 options.preferred_authentications = authmethods_get(); 410 411 /* setup authentication context */ 412 memset(&authctxt, 0, sizeof(authctxt)); 413 pubkey_prepare(&authctxt); 414 authctxt.server_user = server_user; 415 authctxt.local_user = local_user; 416 authctxt.host = host; 417 authctxt.service = "ssh-connection"; /* service name */ 418 authctxt.success = 0; 419 authctxt.method = authmethod_lookup("none"); 420 authctxt.authlist = NULL; 421 authctxt.methoddata = NULL; 422 authctxt.sensitive = sensitive; 423 authctxt.info_req_seen = 0; 424 if (authctxt.method == NULL) 425 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 426 427 /* initial userauth request */ 428 userauth_none(&authctxt); 429 430 dispatch_init(&input_userauth_error); 431 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 432 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 433 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 434 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 435 436 pubkey_cleanup(&authctxt); 437 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 438 439 /* if the user wants to use the none cipher do it */ 440 /* post authentication and only if the right conditions are met */ 441 /* both of the NONE commands must be true and there must be no */ 442 /* tty allocated */ 443 if ((options.none_switch == 1) && (options.none_enabled == 1)) 444 { 445 if (!tty_flag) /* no null on tty sessions */ 446 { 447 debug("Requesting none rekeying..."); 448 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 449 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 450 kex_prop2buf(&xxx_kex->my,myproposal); 451 packet_request_rekeying(); 452 fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n"); 453 } 454 else 455 { 456 /* requested NONE cipher when in a tty */ 457 debug("Cannot switch to NONE cipher with tty allocated"); 458 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 459 } 460 } 461 debug("Authentication succeeded (%s).", authctxt.method->name); 462 } 463 464 void 465 userauth(Authctxt *authctxt, char *authlist) 466 { 467 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 468 authctxt->method->cleanup(authctxt); 469 470 if (authctxt->methoddata) { 471 xfree(authctxt->methoddata); 472 authctxt->methoddata = NULL; 473 } 474 if (authlist == NULL) { 475 authlist = authctxt->authlist; 476 } else { 477 if (authctxt->authlist) 478 xfree(authctxt->authlist); 479 authctxt->authlist = authlist; 480 } 481 for (;;) { 482 Authmethod *method = authmethod_get(authlist); 483 if (method == NULL) 484 fatal("Permission denied (%s).", authlist); 485 authctxt->method = method; 486 487 /* reset the per method handler */ 488 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 489 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 490 491 /* and try new method */ 492 if (method->userauth(authctxt) != 0) { 493 debug2("we sent a %s packet, wait for reply", method->name); 494 break; 495 } else { 496 debug2("we did not send a packet, disable method"); 497 method->enabled = NULL; 498 } 499 } 500 } 501 502 /* ARGSUSED */ 503 void 504 input_userauth_error(int type, u_int32_t seq, void *ctxt) 505 { 506 fatal("input_userauth_error: bad message during authentication: " 507 "type %d", type); 508 } 509 510 /* ARGSUSED */ 511 void 512 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 513 { 514 char *msg, *raw, *lang; 515 u_int len; 516 517 debug3("input_userauth_banner"); 518 raw = packet_get_string(&len); 519 lang = packet_get_string(NULL); 520 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 521 if (len > 65536) 522 len = 65536; 523 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 524 strvisx(msg, raw, len, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 525 fprintf(stderr, "%s", msg); 526 xfree(msg); 527 } 528 xfree(raw); 529 xfree(lang); 530 } 531 532 /* ARGSUSED */ 533 void 534 input_userauth_success(int type, u_int32_t seq, void *ctxt) 535 { 536 Authctxt *authctxt = ctxt; 537 538 if (authctxt == NULL) 539 fatal("input_userauth_success: no authentication context"); 540 if (authctxt->authlist) { 541 xfree(authctxt->authlist); 542 authctxt->authlist = NULL; 543 } 544 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 545 authctxt->method->cleanup(authctxt); 546 if (authctxt->methoddata) { 547 xfree(authctxt->methoddata); 548 authctxt->methoddata = NULL; 549 } 550 authctxt->success = 1; /* break out */ 551 } 552 553 void 554 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 555 { 556 Authctxt *authctxt = ctxt; 557 558 if (authctxt == NULL) 559 fatal("%s: no authentication context", __func__); 560 561 fatal("Unexpected authentication success during %s.", 562 authctxt->method->name); 563 } 564 565 /* ARGSUSED */ 566 void 567 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 568 { 569 Authctxt *authctxt = ctxt; 570 char *authlist = NULL; 571 int partial; 572 573 if (authctxt == NULL) 574 fatal("input_userauth_failure: no authentication context"); 575 576 authlist = packet_get_string(NULL); 577 partial = packet_get_char(); 578 packet_check_eom(); 579 580 if (partial != 0) 581 logit("Authenticated with partial success."); 582 debug("Authentications that can continue: %s", authlist); 583 584 userauth(authctxt, authlist); 585 } 586 587 /* ARGSUSED */ 588 void 589 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 590 { 591 Authctxt *authctxt = ctxt; 592 Key *key = NULL; 593 Identity *id = NULL; 594 Buffer b; 595 int pktype, sent = 0; 596 u_int alen, blen; 597 char *pkalg, *fp; 598 u_char *pkblob; 599 600 if (authctxt == NULL) 601 fatal("input_userauth_pk_ok: no authentication context"); 602 if (datafellows & SSH_BUG_PKOK) { 603 /* this is similar to SSH_BUG_PKAUTH */ 604 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 605 pkblob = packet_get_string(&blen); 606 buffer_init(&b); 607 buffer_append(&b, pkblob, blen); 608 pkalg = buffer_get_string(&b, &alen); 609 buffer_free(&b); 610 } else { 611 pkalg = packet_get_string(&alen); 612 pkblob = packet_get_string(&blen); 613 } 614 packet_check_eom(); 615 616 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 617 618 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 619 debug("unknown pkalg %s", pkalg); 620 goto done; 621 } 622 if ((key = key_from_blob(pkblob, blen)) == NULL) { 623 debug("no key from blob. pkalg %s", pkalg); 624 goto done; 625 } 626 if (key->type != pktype) { 627 error("input_userauth_pk_ok: type mismatch " 628 "for decoded key (received %d, expected %d)", 629 key->type, pktype); 630 goto done; 631 } 632 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 633 debug2("input_userauth_pk_ok: fp %s", fp); 634 xfree(fp); 635 636 /* 637 * search keys in the reverse order, because last candidate has been 638 * moved to the end of the queue. this also avoids confusion by 639 * duplicate keys 640 */ 641 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 642 if (key_equal(key, id->key)) { 643 sent = sign_and_send_pubkey(authctxt, id); 644 break; 645 } 646 } 647 done: 648 if (key != NULL) 649 key_free(key); 650 xfree(pkalg); 651 xfree(pkblob); 652 653 /* try another method if we did not send a packet */ 654 if (sent == 0) 655 userauth(authctxt, NULL); 656 } 657 658 #ifdef GSSAPI 659 int 660 userauth_gssapi(Authctxt *authctxt) 661 { 662 Gssctxt *gssctxt = NULL; 663 static gss_OID_set gss_supported = NULL; 664 static u_int mech = 0; 665 OM_uint32 min; 666 int ok = 0; 667 668 /* Try one GSSAPI method at a time, rather than sending them all at 669 * once. */ 670 671 if (gss_supported == NULL) 672 gss_indicate_mechs(&min, &gss_supported); 673 674 /* Check to see if the mechanism is usable before we offer it */ 675 while (mech < gss_supported->count && !ok) { 676 /* My DER encoding requires length<128 */ 677 if (gss_supported->elements[mech].length < 128 && 678 ssh_gssapi_check_mechanism(&gssctxt, 679 &gss_supported->elements[mech], authctxt->host)) { 680 ok = 1; /* Mechanism works */ 681 } else { 682 mech++; 683 } 684 } 685 686 if (!ok) { 687 ssh_gssapi_delete_ctx(&gssctxt); 688 return 0; 689 } 690 691 authctxt->methoddata=(void *)gssctxt; 692 693 packet_start(SSH2_MSG_USERAUTH_REQUEST); 694 packet_put_cstring(authctxt->server_user); 695 packet_put_cstring(authctxt->service); 696 packet_put_cstring(authctxt->method->name); 697 698 packet_put_int(1); 699 700 packet_put_int((gss_supported->elements[mech].length) + 2); 701 packet_put_char(SSH_GSS_OIDTYPE); 702 packet_put_char(gss_supported->elements[mech].length); 703 packet_put_raw(gss_supported->elements[mech].elements, 704 gss_supported->elements[mech].length); 705 706 packet_send(); 707 708 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 709 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 710 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 711 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 712 713 mech++; /* Move along to next candidate */ 714 715 return 1; 716 } 717 718 static OM_uint32 719 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 720 { 721 Authctxt *authctxt = ctxt; 722 Gssctxt *gssctxt = authctxt->methoddata; 723 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 724 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 725 gss_buffer_desc gssbuf; 726 OM_uint32 status, ms, flags; 727 Buffer b; 728 729 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 730 recv_tok, &send_tok, &flags); 731 732 if (send_tok.length > 0) { 733 if (GSS_ERROR(status)) 734 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 735 else 736 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 737 738 packet_put_string(send_tok.value, send_tok.length); 739 packet_send(); 740 gss_release_buffer(&ms, &send_tok); 741 } 742 743 if (status == GSS_S_COMPLETE) { 744 /* send either complete or MIC, depending on mechanism */ 745 if (!(flags & GSS_C_INTEG_FLAG)) { 746 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 747 packet_send(); 748 } else { 749 ssh_gssapi_buildmic(&b, authctxt->server_user, 750 authctxt->service, "gssapi-with-mic"); 751 752 gssbuf.value = buffer_ptr(&b); 753 gssbuf.length = buffer_len(&b); 754 755 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 756 757 if (!GSS_ERROR(status)) { 758 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 759 packet_put_string(mic.value, mic.length); 760 761 packet_send(); 762 } 763 764 buffer_free(&b); 765 gss_release_buffer(&ms, &mic); 766 } 767 } 768 769 return status; 770 } 771 772 /* ARGSUSED */ 773 void 774 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 775 { 776 Authctxt *authctxt = ctxt; 777 Gssctxt *gssctxt; 778 int oidlen; 779 char *oidv; 780 781 if (authctxt == NULL) 782 fatal("input_gssapi_response: no authentication context"); 783 gssctxt = authctxt->methoddata; 784 785 /* Setup our OID */ 786 oidv = packet_get_string(&oidlen); 787 788 if (oidlen <= 2 || 789 oidv[0] != SSH_GSS_OIDTYPE || 790 oidv[1] != oidlen - 2) { 791 xfree(oidv); 792 debug("Badly encoded mechanism OID received"); 793 userauth(authctxt, NULL); 794 return; 795 } 796 797 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 798 fatal("Server returned different OID than expected"); 799 800 packet_check_eom(); 801 802 xfree(oidv); 803 804 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 805 /* Start again with next method on list */ 806 debug("Trying to start again"); 807 userauth(authctxt, NULL); 808 return; 809 } 810 } 811 812 /* ARGSUSED */ 813 void 814 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 815 { 816 Authctxt *authctxt = ctxt; 817 gss_buffer_desc recv_tok; 818 OM_uint32 status; 819 u_int slen; 820 821 if (authctxt == NULL) 822 fatal("input_gssapi_response: no authentication context"); 823 824 recv_tok.value = packet_get_string(&slen); 825 recv_tok.length = slen; /* safe typecast */ 826 827 packet_check_eom(); 828 829 status = process_gssapi_token(ctxt, &recv_tok); 830 831 xfree(recv_tok.value); 832 833 if (GSS_ERROR(status)) { 834 /* Start again with the next method in the list */ 835 userauth(authctxt, NULL); 836 return; 837 } 838 } 839 840 /* ARGSUSED */ 841 void 842 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 843 { 844 Authctxt *authctxt = ctxt; 845 Gssctxt *gssctxt; 846 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 847 gss_buffer_desc recv_tok; 848 OM_uint32 status, ms; 849 u_int len; 850 851 if (authctxt == NULL) 852 fatal("input_gssapi_response: no authentication context"); 853 gssctxt = authctxt->methoddata; 854 855 recv_tok.value = packet_get_string(&len); 856 recv_tok.length = len; 857 858 packet_check_eom(); 859 860 /* Stick it into GSSAPI and see what it says */ 861 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 862 &recv_tok, &send_tok, NULL); 863 864 xfree(recv_tok.value); 865 gss_release_buffer(&ms, &send_tok); 866 867 /* Server will be returning a failed packet after this one */ 868 } 869 870 /* ARGSUSED */ 871 void 872 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 873 { 874 OM_uint32 maj, min; 875 char *msg; 876 char *lang; 877 878 maj=packet_get_int(); 879 min=packet_get_int(); 880 msg=packet_get_string(NULL); 881 lang=packet_get_string(NULL); 882 883 packet_check_eom(); 884 885 debug("Server GSSAPI Error:\n%s", msg); 886 xfree(msg); 887 xfree(lang); 888 } 889 #endif /* GSSAPI */ 890 891 int 892 userauth_none(Authctxt *authctxt) 893 { 894 /* initial userauth request */ 895 packet_start(SSH2_MSG_USERAUTH_REQUEST); 896 packet_put_cstring(authctxt->server_user); 897 packet_put_cstring(authctxt->service); 898 packet_put_cstring(authctxt->method->name); 899 packet_send(); 900 return 1; 901 } 902 903 int 904 userauth_passwd(Authctxt *authctxt) 905 { 906 static int attempt = 0; 907 char prompt[150]; 908 char *password; 909 const char *host = options.host_key_alias ? options.host_key_alias : 910 authctxt->host; 911 912 if (attempt++ >= options.number_of_password_prompts) 913 return 0; 914 915 if (attempt != 1) 916 error("Permission denied, please try again."); 917 918 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 919 authctxt->server_user, host); 920 password = read_passphrase(prompt, 0); 921 packet_start(SSH2_MSG_USERAUTH_REQUEST); 922 packet_put_cstring(authctxt->server_user); 923 packet_put_cstring(authctxt->service); 924 packet_put_cstring(authctxt->method->name); 925 packet_put_char(0); 926 packet_put_cstring(password); 927 memset(password, 0, strlen(password)); 928 xfree(password); 929 packet_add_padding(64); 930 packet_send(); 931 932 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 933 &input_userauth_passwd_changereq); 934 935 return 1; 936 } 937 938 /* 939 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 940 */ 941 /* ARGSUSED */ 942 void 943 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 944 { 945 Authctxt *authctxt = ctxt; 946 char *info, *lang, *password = NULL, *retype = NULL; 947 char prompt[150]; 948 const char *host = options.host_key_alias ? options.host_key_alias : 949 authctxt->host; 950 951 debug2("input_userauth_passwd_changereq"); 952 953 if (authctxt == NULL) 954 fatal("input_userauth_passwd_changereq: " 955 "no authentication context"); 956 957 info = packet_get_string(NULL); 958 lang = packet_get_string(NULL); 959 if (strlen(info) > 0) 960 logit("%s", info); 961 xfree(info); 962 xfree(lang); 963 packet_start(SSH2_MSG_USERAUTH_REQUEST); 964 packet_put_cstring(authctxt->server_user); 965 packet_put_cstring(authctxt->service); 966 packet_put_cstring(authctxt->method->name); 967 packet_put_char(1); /* additional info */ 968 snprintf(prompt, sizeof(prompt), 969 "Enter %.30s@%.128s's old password: ", 970 authctxt->server_user, host); 971 password = read_passphrase(prompt, 0); 972 packet_put_cstring(password); 973 memset(password, 0, strlen(password)); 974 xfree(password); 975 password = NULL; 976 while (password == NULL) { 977 snprintf(prompt, sizeof(prompt), 978 "Enter %.30s@%.128s's new password: ", 979 authctxt->server_user, host); 980 password = read_passphrase(prompt, RP_ALLOW_EOF); 981 if (password == NULL) { 982 /* bail out */ 983 return; 984 } 985 snprintf(prompt, sizeof(prompt), 986 "Retype %.30s@%.128s's new password: ", 987 authctxt->server_user, host); 988 retype = read_passphrase(prompt, 0); 989 if (strcmp(password, retype) != 0) { 990 memset(password, 0, strlen(password)); 991 xfree(password); 992 logit("Mismatch; try again, EOF to quit."); 993 password = NULL; 994 } 995 memset(retype, 0, strlen(retype)); 996 xfree(retype); 997 } 998 packet_put_cstring(password); 999 memset(password, 0, strlen(password)); 1000 xfree(password); 1001 packet_add_padding(64); 1002 packet_send(); 1003 1004 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1005 &input_userauth_passwd_changereq); 1006 } 1007 1008 #ifdef JPAKE 1009 static char * 1010 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 1011 { 1012 /* OpenBSD crypt(3) handles all of these */ 1013 if (strcmp(crypt_scheme, "crypt") == 0 || 1014 strcmp(crypt_scheme, "bcrypt") == 0 || 1015 strcmp(crypt_scheme, "md5crypt") == 0 || 1016 strcmp(crypt_scheme, "crypt-extended") == 0) 1017 return xstrdup(crypt(password, salt)); 1018 error("%s: unsupported password encryption scheme \"%.100s\"", 1019 __func__, crypt_scheme); 1020 return NULL; 1021 } 1022 1023 static BIGNUM * 1024 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 1025 const char *salt) 1026 { 1027 char prompt[256], *password, *crypted; 1028 u_char *secret; 1029 u_int secret_len; 1030 BIGNUM *ret; 1031 1032 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 1033 authctxt->server_user, authctxt->host); 1034 password = read_passphrase(prompt, 0); 1035 1036 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 1037 logit("Disabling %s authentication", authctxt->method->name); 1038 authctxt->method->enabled = NULL; 1039 /* Continue with an empty password to fail gracefully */ 1040 crypted = xstrdup(""); 1041 } 1042 1043 #ifdef JPAKE_DEBUG 1044 debug3("%s: salt = %s", __func__, salt); 1045 debug3("%s: scheme = %s", __func__, crypt_scheme); 1046 debug3("%s: crypted = %s", __func__, crypted); 1047 #endif 1048 1049 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 1050 &secret, &secret_len) != 0) 1051 fatal("%s: hash_buffer", __func__); 1052 1053 bzero(password, strlen(password)); 1054 bzero(crypted, strlen(crypted)); 1055 xfree(password); 1056 xfree(crypted); 1057 1058 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1059 fatal("%s: BN_bin2bn (secret)", __func__); 1060 bzero(secret, secret_len); 1061 xfree(secret); 1062 1063 return ret; 1064 } 1065 1066 /* ARGSUSED */ 1067 void 1068 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1069 { 1070 Authctxt *authctxt = ctxt; 1071 struct jpake_ctx *pctx = authctxt->methoddata; 1072 u_char *x3_proof, *x4_proof, *x2_s_proof; 1073 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1074 char *crypt_scheme, *salt; 1075 1076 /* Disable this message */ 1077 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1078 1079 if ((pctx->g_x3 = BN_new()) == NULL || 1080 (pctx->g_x4 = BN_new()) == NULL) 1081 fatal("%s: BN_new", __func__); 1082 1083 /* Fetch step 1 values */ 1084 crypt_scheme = packet_get_string(NULL); 1085 salt = packet_get_string(NULL); 1086 pctx->server_id = packet_get_string(&pctx->server_id_len); 1087 packet_get_bignum2(pctx->g_x3); 1088 packet_get_bignum2(pctx->g_x4); 1089 x3_proof = packet_get_string(&x3_proof_len); 1090 x4_proof = packet_get_string(&x4_proof_len); 1091 packet_check_eom(); 1092 1093 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1094 1095 /* Obtain password and derive secret */ 1096 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1097 bzero(crypt_scheme, strlen(crypt_scheme)); 1098 bzero(salt, strlen(salt)); 1099 xfree(crypt_scheme); 1100 xfree(salt); 1101 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1102 1103 /* Calculate step 2 values */ 1104 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1105 pctx->g_x3, pctx->g_x4, pctx->x2, 1106 pctx->server_id, pctx->server_id_len, 1107 pctx->client_id, pctx->client_id_len, 1108 x3_proof, x3_proof_len, 1109 x4_proof, x4_proof_len, 1110 &pctx->a, 1111 &x2_s_proof, &x2_s_proof_len); 1112 1113 bzero(x3_proof, x3_proof_len); 1114 bzero(x4_proof, x4_proof_len); 1115 xfree(x3_proof); 1116 xfree(x4_proof); 1117 1118 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1119 1120 /* Send values for step 2 */ 1121 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1122 packet_put_bignum2(pctx->a); 1123 packet_put_string(x2_s_proof, x2_s_proof_len); 1124 packet_send(); 1125 1126 bzero(x2_s_proof, x2_s_proof_len); 1127 xfree(x2_s_proof); 1128 1129 /* Expect step 2 packet from peer */ 1130 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1131 input_userauth_jpake_server_step2); 1132 } 1133 1134 /* ARGSUSED */ 1135 void 1136 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1137 { 1138 Authctxt *authctxt = ctxt; 1139 struct jpake_ctx *pctx = authctxt->methoddata; 1140 u_char *x4_s_proof; 1141 u_int x4_s_proof_len; 1142 1143 /* Disable this message */ 1144 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1145 1146 if ((pctx->b = BN_new()) == NULL) 1147 fatal("%s: BN_new", __func__); 1148 1149 /* Fetch step 2 values */ 1150 packet_get_bignum2(pctx->b); 1151 x4_s_proof = packet_get_string(&x4_s_proof_len); 1152 packet_check_eom(); 1153 1154 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1155 1156 /* Derive shared key and calculate confirmation hash */ 1157 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1158 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1159 pctx->client_id, pctx->client_id_len, 1160 pctx->server_id, pctx->server_id_len, 1161 session_id2, session_id2_len, 1162 x4_s_proof, x4_s_proof_len, 1163 &pctx->k, 1164 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1165 1166 bzero(x4_s_proof, x4_s_proof_len); 1167 xfree(x4_s_proof); 1168 1169 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1170 1171 /* Send key confirmation proof */ 1172 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1173 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1174 packet_send(); 1175 1176 /* Expect confirmation from peer */ 1177 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1178 input_userauth_jpake_server_confirm); 1179 } 1180 1181 /* ARGSUSED */ 1182 void 1183 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1184 { 1185 Authctxt *authctxt = ctxt; 1186 struct jpake_ctx *pctx = authctxt->methoddata; 1187 1188 /* Disable this message */ 1189 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1190 1191 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1192 packet_check_eom(); 1193 1194 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1195 1196 /* Verify expected confirmation hash */ 1197 if (jpake_check_confirm(pctx->k, 1198 pctx->server_id, pctx->server_id_len, 1199 session_id2, session_id2_len, 1200 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1201 debug("%s: %s success", __func__, authctxt->method->name); 1202 else { 1203 debug("%s: confirmation mismatch", __func__); 1204 /* XXX stash this so if auth succeeds then we can warn/kill */ 1205 } 1206 1207 userauth_jpake_cleanup(authctxt); 1208 } 1209 #endif /* JPAKE */ 1210 1211 static int 1212 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1213 u_char *data, u_int datalen) 1214 { 1215 Key *prv; 1216 int ret; 1217 1218 /* the agent supports this key */ 1219 if (id->ac) 1220 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1221 data, datalen)); 1222 /* 1223 * we have already loaded the private key or 1224 * the private key is stored in external hardware 1225 */ 1226 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1227 return (key_sign(id->key, sigp, lenp, data, datalen)); 1228 /* load the private key from the file */ 1229 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 1230 return (-1); 1231 ret = key_sign(prv, sigp, lenp, data, datalen); 1232 key_free(prv); 1233 return (ret); 1234 } 1235 1236 static int 1237 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1238 { 1239 Buffer b; 1240 u_char *blob, *signature; 1241 u_int bloblen, slen; 1242 u_int skip = 0; 1243 int ret = -1; 1244 int have_sig = 1; 1245 char *fp; 1246 1247 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1248 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1249 xfree(fp); 1250 1251 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1252 /* we cannot handle this key */ 1253 debug3("sign_and_send_pubkey: cannot handle key"); 1254 return 0; 1255 } 1256 /* data to be signed */ 1257 buffer_init(&b); 1258 if (datafellows & SSH_OLD_SESSIONID) { 1259 buffer_append(&b, session_id2, session_id2_len); 1260 skip = session_id2_len; 1261 } else { 1262 buffer_put_string(&b, session_id2, session_id2_len); 1263 skip = buffer_len(&b); 1264 } 1265 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1266 buffer_put_cstring(&b, authctxt->server_user); 1267 buffer_put_cstring(&b, 1268 datafellows & SSH_BUG_PKSERVICE ? 1269 "ssh-userauth" : 1270 authctxt->service); 1271 if (datafellows & SSH_BUG_PKAUTH) { 1272 buffer_put_char(&b, have_sig); 1273 } else { 1274 buffer_put_cstring(&b, authctxt->method->name); 1275 buffer_put_char(&b, have_sig); 1276 buffer_put_cstring(&b, key_ssh_name(id->key)); 1277 } 1278 buffer_put_string(&b, blob, bloblen); 1279 1280 /* generate signature */ 1281 ret = identity_sign(id, &signature, &slen, 1282 buffer_ptr(&b), buffer_len(&b)); 1283 if (ret == -1) { 1284 xfree(blob); 1285 buffer_free(&b); 1286 return 0; 1287 } 1288 #ifdef DEBUG_PK 1289 buffer_dump(&b); 1290 #endif 1291 if (datafellows & SSH_BUG_PKSERVICE) { 1292 buffer_clear(&b); 1293 buffer_append(&b, session_id2, session_id2_len); 1294 skip = session_id2_len; 1295 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1296 buffer_put_cstring(&b, authctxt->server_user); 1297 buffer_put_cstring(&b, authctxt->service); 1298 buffer_put_cstring(&b, authctxt->method->name); 1299 buffer_put_char(&b, have_sig); 1300 if (!(datafellows & SSH_BUG_PKAUTH)) 1301 buffer_put_cstring(&b, key_ssh_name(id->key)); 1302 buffer_put_string(&b, blob, bloblen); 1303 } 1304 xfree(blob); 1305 1306 /* append signature */ 1307 buffer_put_string(&b, signature, slen); 1308 xfree(signature); 1309 1310 /* skip session id and packet type */ 1311 if (buffer_len(&b) < skip + 1) 1312 fatal("userauth_pubkey: internal error"); 1313 buffer_consume(&b, skip + 1); 1314 1315 /* put remaining data from buffer into packet */ 1316 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1317 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1318 buffer_free(&b); 1319 packet_send(); 1320 1321 return 1; 1322 } 1323 1324 static int 1325 send_pubkey_test(Authctxt *authctxt, Identity *id) 1326 { 1327 u_char *blob; 1328 u_int bloblen, have_sig = 0; 1329 1330 debug3("send_pubkey_test"); 1331 1332 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1333 /* we cannot handle this key */ 1334 debug3("send_pubkey_test: cannot handle key"); 1335 return 0; 1336 } 1337 /* register callback for USERAUTH_PK_OK message */ 1338 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1339 1340 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1341 packet_put_cstring(authctxt->server_user); 1342 packet_put_cstring(authctxt->service); 1343 packet_put_cstring(authctxt->method->name); 1344 packet_put_char(have_sig); 1345 if (!(datafellows & SSH_BUG_PKAUTH)) 1346 packet_put_cstring(key_ssh_name(id->key)); 1347 packet_put_string(blob, bloblen); 1348 xfree(blob); 1349 packet_send(); 1350 return 1; 1351 } 1352 1353 static Key * 1354 load_identity_file(char *filename, int userprovided) 1355 { 1356 Key *private; 1357 char prompt[300], *passphrase; 1358 int perm_ok = 0, quit, i; 1359 struct stat st; 1360 1361 if (stat(filename, &st) < 0) { 1362 (userprovided ? logit : debug3)("no such identity: %s: %s", 1363 filename, strerror(errno)); 1364 return NULL; 1365 } 1366 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1367 if (!perm_ok) 1368 return NULL; 1369 if (private == NULL) { 1370 if (options.batch_mode) 1371 return NULL; 1372 snprintf(prompt, sizeof prompt, 1373 "Enter passphrase for key '%.100s': ", filename); 1374 for (i = 0; i < options.number_of_password_prompts; i++) { 1375 passphrase = read_passphrase(prompt, 0); 1376 if (strcmp(passphrase, "") != 0) { 1377 private = key_load_private_type(KEY_UNSPEC, 1378 filename, passphrase, NULL, NULL); 1379 quit = 0; 1380 } else { 1381 debug2("no passphrase given, try next key"); 1382 quit = 1; 1383 } 1384 memset(passphrase, 0, strlen(passphrase)); 1385 xfree(passphrase); 1386 if (private != NULL || quit) 1387 break; 1388 debug2("bad passphrase given, try again..."); 1389 } 1390 } 1391 return private; 1392 } 1393 1394 /* 1395 * try keys in the following order: 1396 * 1. agent keys that are found in the config file 1397 * 2. other agent keys 1398 * 3. keys that are only listed in the config file 1399 */ 1400 static void 1401 pubkey_prepare(Authctxt *authctxt) 1402 { 1403 Identity *id, *id2, *tmp; 1404 Idlist agent, files, *preferred; 1405 Key *key; 1406 AuthenticationConnection *ac; 1407 char *comment; 1408 int i, found; 1409 1410 TAILQ_INIT(&agent); /* keys from the agent */ 1411 TAILQ_INIT(&files); /* keys from the config file */ 1412 preferred = &authctxt->keys; 1413 TAILQ_INIT(preferred); /* preferred order of keys */ 1414 1415 /* list of keys stored in the filesystem and PKCS#11 */ 1416 for (i = 0; i < options.num_identity_files; i++) { 1417 key = options.identity_keys[i]; 1418 if (key && key->type == KEY_RSA1) 1419 continue; 1420 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1421 continue; 1422 options.identity_keys[i] = NULL; 1423 id = xcalloc(1, sizeof(*id)); 1424 id->key = key; 1425 id->filename = xstrdup(options.identity_files[i]); 1426 id->userprovided = options.identity_file_userprovided[i]; 1427 TAILQ_INSERT_TAIL(&files, id, next); 1428 } 1429 /* Prefer PKCS11 keys that are explicitly listed */ 1430 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1431 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1432 continue; 1433 found = 0; 1434 TAILQ_FOREACH(id2, &files, next) { 1435 if (id2->key == NULL || 1436 (id2->key->flags & KEY_FLAG_EXT) != 0) 1437 continue; 1438 if (key_equal(id->key, id2->key)) { 1439 TAILQ_REMOVE(&files, id, next); 1440 TAILQ_INSERT_TAIL(preferred, id, next); 1441 found = 1; 1442 break; 1443 } 1444 } 1445 /* If IdentitiesOnly set and key not found then don't use it */ 1446 if (!found && options.identities_only) { 1447 TAILQ_REMOVE(&files, id, next); 1448 bzero(id, sizeof(id)); 1449 free(id); 1450 } 1451 } 1452 /* list of keys supported by the agent */ 1453 if ((ac = ssh_get_authentication_connection())) { 1454 for (key = ssh_get_first_identity(ac, &comment, 2); 1455 key != NULL; 1456 key = ssh_get_next_identity(ac, &comment, 2)) { 1457 found = 0; 1458 TAILQ_FOREACH(id, &files, next) { 1459 /* agent keys from the config file are preferred */ 1460 if (key_equal(key, id->key)) { 1461 key_free(key); 1462 xfree(comment); 1463 TAILQ_REMOVE(&files, id, next); 1464 TAILQ_INSERT_TAIL(preferred, id, next); 1465 id->ac = ac; 1466 found = 1; 1467 break; 1468 } 1469 } 1470 if (!found && !options.identities_only) { 1471 id = xcalloc(1, sizeof(*id)); 1472 id->key = key; 1473 id->filename = comment; 1474 id->ac = ac; 1475 TAILQ_INSERT_TAIL(&agent, id, next); 1476 } 1477 } 1478 /* append remaining agent keys */ 1479 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1480 TAILQ_REMOVE(&agent, id, next); 1481 TAILQ_INSERT_TAIL(preferred, id, next); 1482 } 1483 authctxt->agent = ac; 1484 } 1485 /* append remaining keys from the config file */ 1486 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1487 TAILQ_REMOVE(&files, id, next); 1488 TAILQ_INSERT_TAIL(preferred, id, next); 1489 } 1490 TAILQ_FOREACH(id, preferred, next) { 1491 debug2("key: %s (%p),%s", id->filename, id->key, 1492 id->userprovided ? " explicit" : ""); 1493 } 1494 } 1495 1496 static void 1497 pubkey_cleanup(Authctxt *authctxt) 1498 { 1499 Identity *id; 1500 1501 if (authctxt->agent != NULL) 1502 ssh_close_authentication_connection(authctxt->agent); 1503 for (id = TAILQ_FIRST(&authctxt->keys); id; 1504 id = TAILQ_FIRST(&authctxt->keys)) { 1505 TAILQ_REMOVE(&authctxt->keys, id, next); 1506 if (id->key) 1507 key_free(id->key); 1508 if (id->filename) 1509 xfree(id->filename); 1510 xfree(id); 1511 } 1512 } 1513 1514 int 1515 userauth_pubkey(Authctxt *authctxt) 1516 { 1517 Identity *id; 1518 int sent = 0; 1519 1520 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1521 if (id->tried++) 1522 return (0); 1523 /* move key to the end of the queue */ 1524 TAILQ_REMOVE(&authctxt->keys, id, next); 1525 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1526 /* 1527 * send a test message if we have the public key. for 1528 * encrypted keys we cannot do this and have to load the 1529 * private key instead 1530 */ 1531 if (id->key && id->key->type != KEY_RSA1) { 1532 debug("Offering %s public key: %s", key_type(id->key), 1533 id->filename); 1534 sent = send_pubkey_test(authctxt, id); 1535 } else if (id->key == NULL) { 1536 debug("Trying private key: %s", id->filename); 1537 id->key = load_identity_file(id->filename, 1538 id->userprovided); 1539 if (id->key != NULL) { 1540 id->isprivate = 1; 1541 sent = sign_and_send_pubkey(authctxt, id); 1542 key_free(id->key); 1543 id->key = NULL; 1544 } 1545 } 1546 if (sent) 1547 return (sent); 1548 } 1549 return (0); 1550 } 1551 1552 /* 1553 * Send userauth request message specifying keyboard-interactive method. 1554 */ 1555 int 1556 userauth_kbdint(Authctxt *authctxt) 1557 { 1558 static int attempt = 0; 1559 1560 if (attempt++ >= options.number_of_password_prompts) 1561 return 0; 1562 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1563 if (attempt > 1 && !authctxt->info_req_seen) { 1564 debug3("userauth_kbdint: disable: no info_req_seen"); 1565 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1566 return 0; 1567 } 1568 1569 debug2("userauth_kbdint"); 1570 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1571 packet_put_cstring(authctxt->server_user); 1572 packet_put_cstring(authctxt->service); 1573 packet_put_cstring(authctxt->method->name); 1574 packet_put_cstring(""); /* lang */ 1575 packet_put_cstring(options.kbd_interactive_devices ? 1576 options.kbd_interactive_devices : ""); 1577 packet_send(); 1578 1579 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1580 return 1; 1581 } 1582 1583 /* 1584 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1585 */ 1586 void 1587 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1588 { 1589 Authctxt *authctxt = ctxt; 1590 char *name, *inst, *lang, *prompt, *response; 1591 u_int num_prompts, i; 1592 int echo = 0; 1593 1594 debug2("input_userauth_info_req"); 1595 1596 if (authctxt == NULL) 1597 fatal("input_userauth_info_req: no authentication context"); 1598 1599 authctxt->info_req_seen = 1; 1600 1601 name = packet_get_string(NULL); 1602 inst = packet_get_string(NULL); 1603 lang = packet_get_string(NULL); 1604 if (strlen(name) > 0) 1605 logit("%s", name); 1606 if (strlen(inst) > 0) 1607 logit("%s", inst); 1608 xfree(name); 1609 xfree(inst); 1610 xfree(lang); 1611 1612 num_prompts = packet_get_int(); 1613 /* 1614 * Begin to build info response packet based on prompts requested. 1615 * We commit to providing the correct number of responses, so if 1616 * further on we run into a problem that prevents this, we have to 1617 * be sure and clean this up and send a correct error response. 1618 */ 1619 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1620 packet_put_int(num_prompts); 1621 1622 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1623 for (i = 0; i < num_prompts; i++) { 1624 prompt = packet_get_string(NULL); 1625 echo = packet_get_char(); 1626 1627 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1628 1629 packet_put_cstring(response); 1630 memset(response, 0, strlen(response)); 1631 xfree(response); 1632 xfree(prompt); 1633 } 1634 packet_check_eom(); /* done with parsing incoming message. */ 1635 1636 packet_add_padding(64); 1637 packet_send(); 1638 } 1639 1640 static int 1641 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1642 u_char *data, u_int datalen) 1643 { 1644 Buffer b; 1645 struct stat st; 1646 pid_t pid; 1647 int to[2], from[2], status, version = 2; 1648 1649 debug2("ssh_keysign called"); 1650 1651 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1652 error("ssh_keysign: not installed: %s", strerror(errno)); 1653 return -1; 1654 } 1655 if (fflush(stdout) != 0) 1656 error("ssh_keysign: fflush: %s", strerror(errno)); 1657 if (pipe(to) < 0) { 1658 error("ssh_keysign: pipe: %s", strerror(errno)); 1659 return -1; 1660 } 1661 if (pipe(from) < 0) { 1662 error("ssh_keysign: pipe: %s", strerror(errno)); 1663 return -1; 1664 } 1665 if ((pid = fork()) < 0) { 1666 error("ssh_keysign: fork: %s", strerror(errno)); 1667 return -1; 1668 } 1669 if (pid == 0) { 1670 /* keep the socket on exec */ 1671 fcntl(packet_get_connection_in(), F_SETFD, 0); 1672 permanently_drop_suid(getuid()); 1673 close(from[0]); 1674 if (dup2(from[1], STDOUT_FILENO) < 0) 1675 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1676 close(to[1]); 1677 if (dup2(to[0], STDIN_FILENO) < 0) 1678 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1679 close(from[1]); 1680 close(to[0]); 1681 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1682 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1683 strerror(errno)); 1684 } 1685 close(from[1]); 1686 close(to[0]); 1687 1688 buffer_init(&b); 1689 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1690 buffer_put_string(&b, data, datalen); 1691 if (ssh_msg_send(to[1], version, &b) == -1) 1692 fatal("ssh_keysign: couldn't send request"); 1693 1694 if (ssh_msg_recv(from[0], &b) < 0) { 1695 error("ssh_keysign: no reply"); 1696 buffer_free(&b); 1697 return -1; 1698 } 1699 close(from[0]); 1700 close(to[1]); 1701 1702 while (waitpid(pid, &status, 0) < 0) 1703 if (errno != EINTR) 1704 break; 1705 1706 if (buffer_get_char(&b) != version) { 1707 error("ssh_keysign: bad version"); 1708 buffer_free(&b); 1709 return -1; 1710 } 1711 *sigp = buffer_get_string(&b, lenp); 1712 buffer_free(&b); 1713 1714 return 0; 1715 } 1716 1717 int 1718 userauth_hostbased(Authctxt *authctxt) 1719 { 1720 Key *private = NULL; 1721 Sensitive *sensitive = authctxt->sensitive; 1722 Buffer b; 1723 u_char *signature, *blob; 1724 char *chost, *pkalg, *p; 1725 const char *service; 1726 u_int blen, slen; 1727 int ok, i, found = 0; 1728 1729 /* check for a useful key */ 1730 for (i = 0; i < sensitive->nkeys; i++) { 1731 private = sensitive->keys[i]; 1732 if (private && private->type != KEY_RSA1) { 1733 found = 1; 1734 /* we take and free the key */ 1735 sensitive->keys[i] = NULL; 1736 break; 1737 } 1738 } 1739 if (!found) { 1740 debug("No more client hostkeys for hostbased authentication."); 1741 return 0; 1742 } 1743 if (key_to_blob(private, &blob, &blen) == 0) { 1744 key_free(private); 1745 return 0; 1746 } 1747 /* figure out a name for the client host */ 1748 p = get_local_name(packet_get_connection_in()); 1749 if (p == NULL) { 1750 error("userauth_hostbased: cannot get local ipaddr/name"); 1751 key_free(private); 1752 xfree(blob); 1753 return 0; 1754 } 1755 xasprintf(&chost, "%s.", p); 1756 debug2("userauth_hostbased: chost %s", chost); 1757 xfree(p); 1758 1759 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1760 authctxt->service; 1761 pkalg = xstrdup(key_ssh_name(private)); 1762 buffer_init(&b); 1763 /* construct data */ 1764 buffer_put_string(&b, session_id2, session_id2_len); 1765 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1766 buffer_put_cstring(&b, authctxt->server_user); 1767 buffer_put_cstring(&b, service); 1768 buffer_put_cstring(&b, authctxt->method->name); 1769 buffer_put_cstring(&b, pkalg); 1770 buffer_put_string(&b, blob, blen); 1771 buffer_put_cstring(&b, chost); 1772 buffer_put_cstring(&b, authctxt->local_user); 1773 #ifdef DEBUG_PK 1774 buffer_dump(&b); 1775 #endif 1776 if (sensitive->external_keysign) 1777 ok = ssh_keysign(private, &signature, &slen, 1778 buffer_ptr(&b), buffer_len(&b)); 1779 else 1780 ok = key_sign(private, &signature, &slen, 1781 buffer_ptr(&b), buffer_len(&b)); 1782 key_free(private); 1783 buffer_free(&b); 1784 if (ok != 0) { 1785 error("key_sign failed"); 1786 xfree(chost); 1787 xfree(pkalg); 1788 xfree(blob); 1789 return 0; 1790 } 1791 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1792 packet_put_cstring(authctxt->server_user); 1793 packet_put_cstring(authctxt->service); 1794 packet_put_cstring(authctxt->method->name); 1795 packet_put_cstring(pkalg); 1796 packet_put_string(blob, blen); 1797 packet_put_cstring(chost); 1798 packet_put_cstring(authctxt->local_user); 1799 packet_put_string(signature, slen); 1800 memset(signature, 's', slen); 1801 xfree(signature); 1802 xfree(chost); 1803 xfree(pkalg); 1804 xfree(blob); 1805 1806 packet_send(); 1807 return 1; 1808 } 1809 1810 #ifdef JPAKE 1811 int 1812 userauth_jpake(Authctxt *authctxt) 1813 { 1814 struct jpake_ctx *pctx; 1815 u_char *x1_proof, *x2_proof; 1816 u_int x1_proof_len, x2_proof_len; 1817 static int attempt = 0; /* XXX share with userauth_password's? */ 1818 1819 if (attempt++ >= options.number_of_password_prompts) 1820 return 0; 1821 if (attempt != 1) 1822 error("Permission denied, please try again."); 1823 1824 if (authctxt->methoddata != NULL) 1825 fatal("%s: authctxt->methoddata already set (%p)", 1826 __func__, authctxt->methoddata); 1827 1828 authctxt->methoddata = pctx = jpake_new(); 1829 1830 /* 1831 * Send request immediately, to get the protocol going while 1832 * we do the initial computations. 1833 */ 1834 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1835 packet_put_cstring(authctxt->server_user); 1836 packet_put_cstring(authctxt->service); 1837 packet_put_cstring(authctxt->method->name); 1838 packet_send(); 1839 packet_write_wait(); 1840 1841 jpake_step1(pctx->grp, 1842 &pctx->client_id, &pctx->client_id_len, 1843 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1844 &x1_proof, &x1_proof_len, 1845 &x2_proof, &x2_proof_len); 1846 1847 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1848 1849 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1850 packet_put_string(pctx->client_id, pctx->client_id_len); 1851 packet_put_bignum2(pctx->g_x1); 1852 packet_put_bignum2(pctx->g_x2); 1853 packet_put_string(x1_proof, x1_proof_len); 1854 packet_put_string(x2_proof, x2_proof_len); 1855 packet_send(); 1856 1857 bzero(x1_proof, x1_proof_len); 1858 bzero(x2_proof, x2_proof_len); 1859 xfree(x1_proof); 1860 xfree(x2_proof); 1861 1862 /* Expect step 1 packet from peer */ 1863 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1864 input_userauth_jpake_server_step1); 1865 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1866 &input_userauth_success_unexpected); 1867 1868 return 1; 1869 } 1870 1871 void 1872 userauth_jpake_cleanup(Authctxt *authctxt) 1873 { 1874 debug3("%s: clean up", __func__); 1875 if (authctxt->methoddata != NULL) { 1876 jpake_free(authctxt->methoddata); 1877 authctxt->methoddata = NULL; 1878 } 1879 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1880 } 1881 #endif /* JPAKE */ 1882 1883 #if KRB5 1884 static int 1885 ssh_krb5_helper(krb5_data *ap) 1886 { 1887 krb5_context xcontext = NULL; /* XXX share with ssh1 */ 1888 krb5_auth_context xauth_context = NULL; 1889 1890 krb5_context *context; 1891 krb5_auth_context *auth_context; 1892 krb5_error_code problem; 1893 const char *tkfile; 1894 struct stat buf; 1895 krb5_ccache ccache = NULL; 1896 const char *remotehost; 1897 int ret; 1898 const char *errtxt; 1899 1900 memset(ap, 0, sizeof(*ap)); 1901 1902 context = &xcontext; 1903 auth_context = &xauth_context; 1904 1905 problem = krb5_init_context(context); 1906 if (problem) { 1907 debug("Kerberos v5: krb5_init_context failed"); 1908 ret = 0; 1909 goto out; 1910 } 1911 1912 tkfile = krb5_cc_default_name(*context); 1913 if (strncmp(tkfile, "FILE:", 5) == 0) 1914 tkfile += 5; 1915 1916 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 1917 debug("Kerberos v5: could not get default ccache (permission denied)."); 1918 ret = 0; 1919 goto out; 1920 } 1921 1922 problem = krb5_cc_default(*context, &ccache); 1923 if (problem) { 1924 errtxt = krb5_get_error_message(*context, problem); 1925 if (errtxt != NULL) { 1926 debug("Kerberos v5: krb5_cc_default failed: %s", 1927 errtxt); 1928 krb5_free_error_message(*context, errtxt); 1929 } else 1930 debug("Kerberos v5: krb5_cc_default failed: %d", 1931 problem); 1932 ret = 0; 1933 goto out; 1934 } 1935 1936 remotehost = get_canonical_hostname(1); 1937 1938 problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, 1939 "host", remotehost, NULL, ccache, ap); 1940 if (problem) { 1941 errtxt = krb5_get_error_message(*context, problem); 1942 if (errtxt != NULL) { 1943 debug("Kerberos v5: krb5_mk_req failed: %s", errtxt); 1944 krb5_free_error_message(*context, errtxt); 1945 } else 1946 debug("Kerberos v5: krb5_mk_req failed: %d", problem); 1947 ret = 0; 1948 goto out; 1949 } 1950 ret = 1; 1951 1952 out: 1953 if (ccache != NULL) 1954 krb5_cc_close(*context, ccache); 1955 if (*auth_context) 1956 krb5_auth_con_free(*context, *auth_context); 1957 if (*context) 1958 krb5_free_context(*context); 1959 return (ret); 1960 } 1961 1962 int 1963 userauth_kerberos(Authctxt *authctxt) 1964 { 1965 krb5_data ap; 1966 1967 if (ssh_krb5_helper(&ap) == 0) 1968 return (0); 1969 1970 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1971 packet_put_cstring(authctxt->server_user); 1972 packet_put_cstring(authctxt->service); 1973 packet_put_cstring(authctxt->method->name); 1974 packet_put_string(ap.data, ap.length); 1975 packet_send(); 1976 1977 krb5_data_free(&ap); 1978 return (1); 1979 } 1980 #endif 1981 1982 /* find auth method */ 1983 1984 /* 1985 * given auth method name, if configurable options permit this method fill 1986 * in auth_ident field and return true, otherwise return false. 1987 */ 1988 static int 1989 authmethod_is_enabled(Authmethod *method) 1990 { 1991 if (method == NULL) 1992 return 0; 1993 /* return false if options indicate this method is disabled */ 1994 if (method->enabled == NULL || *method->enabled == 0) 1995 return 0; 1996 /* return false if batch mode is enabled but method needs interactive mode */ 1997 if (method->batch_flag != NULL && *method->batch_flag != 0) 1998 return 0; 1999 return 1; 2000 } 2001 2002 static Authmethod * 2003 authmethod_lookup(const char *name) 2004 { 2005 Authmethod *method = NULL; 2006 if (name != NULL) 2007 for (method = authmethods; method->name != NULL; method++) 2008 if (strcmp(name, method->name) == 0) 2009 return method; 2010 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2011 return NULL; 2012 } 2013 2014 /* XXX internal state */ 2015 static Authmethod *current = NULL; 2016 static char *supported = NULL; 2017 static char *preferred = NULL; 2018 2019 /* 2020 * Given the authentication method list sent by the server, return the 2021 * next method we should try. If the server initially sends a nil list, 2022 * use a built-in default list. 2023 */ 2024 static Authmethod * 2025 authmethod_get(char *authlist) 2026 { 2027 char *name = NULL; 2028 u_int next; 2029 2030 /* Use a suitable default if we're passed a nil list. */ 2031 if (authlist == NULL || strlen(authlist) == 0) 2032 authlist = options.preferred_authentications; 2033 2034 if (supported == NULL || strcmp(authlist, supported) != 0) { 2035 debug3("start over, passed a different list %s", authlist); 2036 if (supported != NULL) 2037 xfree(supported); 2038 supported = xstrdup(authlist); 2039 preferred = options.preferred_authentications; 2040 debug3("preferred %s", preferred); 2041 current = NULL; 2042 } else if (current != NULL && authmethod_is_enabled(current)) 2043 return current; 2044 2045 for (;;) { 2046 if ((name = match_list(preferred, supported, &next)) == NULL) { 2047 debug("No more authentication methods to try."); 2048 current = NULL; 2049 return NULL; 2050 } 2051 preferred += next; 2052 debug3("authmethod_lookup %s", name); 2053 debug3("remaining preferred: %s", preferred); 2054 if ((current = authmethod_lookup(name)) != NULL && 2055 authmethod_is_enabled(current)) { 2056 debug3("authmethod_is_enabled %s", name); 2057 debug("Next authentication method: %s", name); 2058 xfree(name); 2059 return current; 2060 } 2061 } 2062 } 2063 2064 static char * 2065 authmethods_get(void) 2066 { 2067 Authmethod *method = NULL; 2068 Buffer b; 2069 char *list; 2070 2071 buffer_init(&b); 2072 for (method = authmethods; method->name != NULL; method++) { 2073 if (authmethod_is_enabled(method)) { 2074 if (buffer_len(&b) > 0) 2075 buffer_append(&b, ",", 1); 2076 buffer_append(&b, method->name, strlen(method->name)); 2077 } 2078 } 2079 buffer_append(&b, "\0", 1); 2080 list = xstrdup(buffer_ptr(&b)); 2081 buffer_free(&b); 2082 return list; 2083 } 2084 2085