1 /* $NetBSD: sshconnect2.c,v 1.11 2012/12/12 17:42:40 christos Exp $ */ 2 /* $OpenBSD: sshconnect2.c,v 1.189 2012/06/22 12:30:26 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 1.11 2012/12/12 17:42:40 christos 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 }; 259 TAILQ_HEAD(idlist, identity); 260 261 struct Authctxt { 262 const char *server_user; 263 const char *local_user; 264 const char *host; 265 const char *service; 266 Authmethod *method; 267 sig_atomic_t success; 268 char *authlist; 269 /* pubkey */ 270 Idlist keys; 271 AuthenticationConnection *agent; 272 /* hostbased */ 273 Sensitive *sensitive; 274 /* kbd-interactive */ 275 int info_req_seen; 276 /* generic */ 277 void *methoddata; 278 }; 279 struct Authmethod { 280 const char *name; /* string to compare against server's list */ 281 int (*userauth)(Authctxt *authctxt); 282 void (*cleanup)(Authctxt *authctxt); 283 int *enabled; /* flag in option struct that enables method */ 284 int *batch_flag; /* flag in option struct that disables method */ 285 }; 286 287 void input_userauth_success(int, u_int32_t, void *); 288 __dead void input_userauth_success_unexpected(int, u_int32_t, void *); 289 void input_userauth_failure(int, u_int32_t, void *); 290 void input_userauth_banner(int, u_int32_t, void *); 291 __dead void input_userauth_error(int, u_int32_t, void *); 292 void input_userauth_info_req(int, u_int32_t, void *); 293 void input_userauth_pk_ok(int, u_int32_t, void *); 294 void input_userauth_passwd_changereq(int, u_int32_t, void *); 295 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 296 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 297 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 298 299 int userauth_none(Authctxt *); 300 int userauth_pubkey(Authctxt *); 301 int userauth_passwd(Authctxt *); 302 int userauth_kbdint(Authctxt *); 303 int userauth_hostbased(Authctxt *); 304 int userauth_kerberos(Authctxt *); 305 int userauth_jpake(Authctxt *); 306 307 void userauth_jpake_cleanup(Authctxt *); 308 309 #ifdef GSSAPI 310 int userauth_gssapi(Authctxt *authctxt); 311 void input_gssapi_response(int type, u_int32_t, void *); 312 void input_gssapi_token(int type, u_int32_t, void *); 313 void input_gssapi_hash(int type, u_int32_t, void *); 314 void input_gssapi_error(int, u_int32_t, void *); 315 void input_gssapi_errtok(int, u_int32_t, void *); 316 #endif 317 318 void userauth(Authctxt *, char *); 319 320 static int sign_and_send_pubkey(Authctxt *, Identity *); 321 static void pubkey_prepare(Authctxt *); 322 static void pubkey_cleanup(Authctxt *); 323 static Key *load_identity_file(char *); 324 325 static Authmethod *authmethod_get(char *authlist); 326 static Authmethod *authmethod_lookup(const char *name); 327 static char *authmethods_get(void); 328 329 Authmethod authmethods[] = { 330 #ifdef GSSAPI 331 {"gssapi-with-mic", 332 userauth_gssapi, 333 NULL, 334 &options.gss_authentication, 335 NULL}, 336 #endif 337 {"hostbased", 338 userauth_hostbased, 339 NULL, 340 &options.hostbased_authentication, 341 NULL}, 342 #if KRB5 343 {"kerberos-2@ssh.com", 344 userauth_kerberos, 345 NULL, 346 &options.kerberos_authentication, 347 NULL}, 348 #endif 349 {"publickey", 350 userauth_pubkey, 351 NULL, 352 &options.pubkey_authentication, 353 NULL}, 354 #ifdef JPAKE 355 {"jpake-01@openssh.com", 356 userauth_jpake, 357 userauth_jpake_cleanup, 358 &options.zero_knowledge_password_authentication, 359 &options.batch_mode}, 360 #endif 361 {"keyboard-interactive", 362 userauth_kbdint, 363 NULL, 364 &options.kbd_interactive_authentication, 365 &options.batch_mode}, 366 {"password", 367 userauth_passwd, 368 NULL, 369 &options.password_authentication, 370 &options.batch_mode}, 371 {"none", 372 userauth_none, 373 NULL, 374 NULL, 375 NULL}, 376 {NULL, NULL, NULL, NULL, NULL} 377 }; 378 379 void 380 ssh_userauth2(const char *local_user, const char *server_user, char *host, 381 Sensitive *sensitive) 382 { 383 Authctxt authctxt; 384 int type; 385 386 if (options.challenge_response_authentication) 387 options.kbd_interactive_authentication = 1; 388 389 packet_start(SSH2_MSG_SERVICE_REQUEST); 390 packet_put_cstring("ssh-userauth"); 391 packet_send(); 392 debug("SSH2_MSG_SERVICE_REQUEST sent"); 393 packet_write_wait(); 394 type = packet_read(); 395 if (type != SSH2_MSG_SERVICE_ACCEPT) 396 fatal("Server denied authentication request: %d", type); 397 if (packet_remaining() > 0) { 398 char *reply = packet_get_string(NULL); 399 debug2("service_accept: %s", reply); 400 xfree(reply); 401 } else { 402 debug2("buggy server: service_accept w/o service"); 403 } 404 packet_check_eom(); 405 debug("SSH2_MSG_SERVICE_ACCEPT received"); 406 407 if (options.preferred_authentications == NULL) 408 options.preferred_authentications = authmethods_get(); 409 410 /* setup authentication context */ 411 memset(&authctxt, 0, sizeof(authctxt)); 412 pubkey_prepare(&authctxt); 413 authctxt.server_user = server_user; 414 authctxt.local_user = local_user; 415 authctxt.host = host; 416 authctxt.service = "ssh-connection"; /* service name */ 417 authctxt.success = 0; 418 authctxt.method = authmethod_lookup("none"); 419 authctxt.authlist = NULL; 420 authctxt.methoddata = NULL; 421 authctxt.sensitive = sensitive; 422 authctxt.info_req_seen = 0; 423 if (authctxt.method == NULL) 424 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 425 426 /* initial userauth request */ 427 userauth_none(&authctxt); 428 429 dispatch_init(&input_userauth_error); 430 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 431 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 432 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 433 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 434 435 pubkey_cleanup(&authctxt); 436 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 437 438 /* if the user wants to use the none cipher do it */ 439 /* post authentication and only if the right conditions are met */ 440 /* both of the NONE commands must be true and there must be no */ 441 /* tty allocated */ 442 if ((options.none_switch == 1) && (options.none_enabled == 1)) 443 { 444 if (!tty_flag) /* no null on tty sessions */ 445 { 446 debug("Requesting none rekeying..."); 447 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 448 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 449 kex_prop2buf(&xxx_kex->my,myproposal); 450 packet_request_rekeying(); 451 fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n"); 452 } 453 else 454 { 455 /* requested NONE cipher when in a tty */ 456 debug("Cannot switch to NONE cipher with tty allocated"); 457 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 458 } 459 } 460 debug("Authentication succeeded (%s).", authctxt.method->name); 461 } 462 463 void 464 userauth(Authctxt *authctxt, char *authlist) 465 { 466 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 467 authctxt->method->cleanup(authctxt); 468 469 if (authctxt->methoddata) { 470 xfree(authctxt->methoddata); 471 authctxt->methoddata = NULL; 472 } 473 if (authlist == NULL) { 474 authlist = authctxt->authlist; 475 } else { 476 if (authctxt->authlist) 477 xfree(authctxt->authlist); 478 authctxt->authlist = authlist; 479 } 480 for (;;) { 481 Authmethod *method = authmethod_get(authlist); 482 if (method == NULL) 483 fatal("Permission denied (%s).", authlist); 484 authctxt->method = method; 485 486 /* reset the per method handler */ 487 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 488 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 489 490 /* and try new method */ 491 if (method->userauth(authctxt) != 0) { 492 debug2("we sent a %s packet, wait for reply", method->name); 493 break; 494 } else { 495 debug2("we did not send a packet, disable method"); 496 method->enabled = NULL; 497 } 498 } 499 } 500 501 /* ARGSUSED */ 502 void 503 input_userauth_error(int type, u_int32_t seq, void *ctxt) 504 { 505 fatal("input_userauth_error: bad message during authentication: " 506 "type %d", type); 507 } 508 509 /* ARGSUSED */ 510 void 511 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 512 { 513 char *msg, *raw, *lang; 514 u_int len; 515 516 debug3("input_userauth_banner"); 517 raw = packet_get_string(&len); 518 lang = packet_get_string(NULL); 519 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 520 if (len > 65536) 521 len = 65536; 522 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 523 strvisx(msg, raw, len, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 524 fprintf(stderr, "%s", msg); 525 xfree(msg); 526 } 527 xfree(raw); 528 xfree(lang); 529 } 530 531 /* ARGSUSED */ 532 void 533 input_userauth_success(int type, u_int32_t seq, void *ctxt) 534 { 535 Authctxt *authctxt = ctxt; 536 537 if (authctxt == NULL) 538 fatal("input_userauth_success: no authentication context"); 539 if (authctxt->authlist) { 540 xfree(authctxt->authlist); 541 authctxt->authlist = NULL; 542 } 543 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 544 authctxt->method->cleanup(authctxt); 545 if (authctxt->methoddata) { 546 xfree(authctxt->methoddata); 547 authctxt->methoddata = NULL; 548 } 549 authctxt->success = 1; /* break out */ 550 } 551 552 void 553 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 554 { 555 Authctxt *authctxt = ctxt; 556 557 if (authctxt == NULL) 558 fatal("%s: no authentication context", __func__); 559 560 fatal("Unexpected authentication success during %s.", 561 authctxt->method->name); 562 } 563 564 /* ARGSUSED */ 565 void 566 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 567 { 568 Authctxt *authctxt = ctxt; 569 char *authlist = NULL; 570 int partial; 571 572 if (authctxt == NULL) 573 fatal("input_userauth_failure: no authentication context"); 574 575 authlist = packet_get_string(NULL); 576 partial = packet_get_char(); 577 packet_check_eom(); 578 579 if (partial != 0) 580 logit("Authenticated with partial success."); 581 debug("Authentications that can continue: %s", authlist); 582 583 userauth(authctxt, authlist); 584 } 585 586 /* ARGSUSED */ 587 void 588 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 589 { 590 Authctxt *authctxt = ctxt; 591 Key *key = NULL; 592 Identity *id = NULL; 593 Buffer b; 594 int pktype, sent = 0; 595 u_int alen, blen; 596 char *pkalg, *fp; 597 u_char *pkblob; 598 599 if (authctxt == NULL) 600 fatal("input_userauth_pk_ok: no authentication context"); 601 if (datafellows & SSH_BUG_PKOK) { 602 /* this is similar to SSH_BUG_PKAUTH */ 603 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 604 pkblob = packet_get_string(&blen); 605 buffer_init(&b); 606 buffer_append(&b, pkblob, blen); 607 pkalg = buffer_get_string(&b, &alen); 608 buffer_free(&b); 609 } else { 610 pkalg = packet_get_string(&alen); 611 pkblob = packet_get_string(&blen); 612 } 613 packet_check_eom(); 614 615 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 616 617 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 618 debug("unknown pkalg %s", pkalg); 619 goto done; 620 } 621 if ((key = key_from_blob(pkblob, blen)) == NULL) { 622 debug("no key from blob. pkalg %s", pkalg); 623 goto done; 624 } 625 if (key->type != pktype) { 626 error("input_userauth_pk_ok: type mismatch " 627 "for decoded key (received %d, expected %d)", 628 key->type, pktype); 629 goto done; 630 } 631 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 632 debug2("input_userauth_pk_ok: fp %s", fp); 633 xfree(fp); 634 635 /* 636 * search keys in the reverse order, because last candidate has been 637 * moved to the end of the queue. this also avoids confusion by 638 * duplicate keys 639 */ 640 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 641 if (key_equal(key, id->key)) { 642 sent = sign_and_send_pubkey(authctxt, id); 643 break; 644 } 645 } 646 done: 647 if (key != NULL) 648 key_free(key); 649 xfree(pkalg); 650 xfree(pkblob); 651 652 /* try another method if we did not send a packet */ 653 if (sent == 0) 654 userauth(authctxt, NULL); 655 } 656 657 #ifdef GSSAPI 658 int 659 userauth_gssapi(Authctxt *authctxt) 660 { 661 Gssctxt *gssctxt = NULL; 662 static gss_OID_set gss_supported = NULL; 663 static u_int mech = 0; 664 OM_uint32 min; 665 int ok = 0; 666 667 /* Try one GSSAPI method at a time, rather than sending them all at 668 * once. */ 669 670 if (gss_supported == NULL) 671 gss_indicate_mechs(&min, &gss_supported); 672 673 /* Check to see if the mechanism is usable before we offer it */ 674 while (mech < gss_supported->count && !ok) { 675 /* My DER encoding requires length<128 */ 676 if (gss_supported->elements[mech].length < 128 && 677 ssh_gssapi_check_mechanism(&gssctxt, 678 &gss_supported->elements[mech], authctxt->host)) { 679 ok = 1; /* Mechanism works */ 680 } else { 681 mech++; 682 } 683 } 684 685 if (!ok) { 686 ssh_gssapi_delete_ctx(&gssctxt); 687 return 0; 688 } 689 690 authctxt->methoddata=(void *)gssctxt; 691 692 packet_start(SSH2_MSG_USERAUTH_REQUEST); 693 packet_put_cstring(authctxt->server_user); 694 packet_put_cstring(authctxt->service); 695 packet_put_cstring(authctxt->method->name); 696 697 packet_put_int(1); 698 699 packet_put_int((gss_supported->elements[mech].length) + 2); 700 packet_put_char(SSH_GSS_OIDTYPE); 701 packet_put_char(gss_supported->elements[mech].length); 702 packet_put_raw(gss_supported->elements[mech].elements, 703 gss_supported->elements[mech].length); 704 705 packet_send(); 706 707 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 708 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 709 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 710 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 711 712 mech++; /* Move along to next candidate */ 713 714 return 1; 715 } 716 717 static OM_uint32 718 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 719 { 720 Authctxt *authctxt = ctxt; 721 Gssctxt *gssctxt = authctxt->methoddata; 722 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 723 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 724 gss_buffer_desc gssbuf; 725 OM_uint32 status, ms, flags; 726 Buffer b; 727 728 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 729 recv_tok, &send_tok, &flags); 730 731 if (send_tok.length > 0) { 732 if (GSS_ERROR(status)) 733 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 734 else 735 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 736 737 packet_put_string(send_tok.value, send_tok.length); 738 packet_send(); 739 gss_release_buffer(&ms, &send_tok); 740 } 741 742 if (status == GSS_S_COMPLETE) { 743 /* send either complete or MIC, depending on mechanism */ 744 if (!(flags & GSS_C_INTEG_FLAG)) { 745 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 746 packet_send(); 747 } else { 748 ssh_gssapi_buildmic(&b, authctxt->server_user, 749 authctxt->service, "gssapi-with-mic"); 750 751 gssbuf.value = buffer_ptr(&b); 752 gssbuf.length = buffer_len(&b); 753 754 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 755 756 if (!GSS_ERROR(status)) { 757 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 758 packet_put_string(mic.value, mic.length); 759 760 packet_send(); 761 } 762 763 buffer_free(&b); 764 gss_release_buffer(&ms, &mic); 765 } 766 } 767 768 return status; 769 } 770 771 /* ARGSUSED */ 772 void 773 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 774 { 775 Authctxt *authctxt = ctxt; 776 Gssctxt *gssctxt; 777 int oidlen; 778 char *oidv; 779 780 if (authctxt == NULL) 781 fatal("input_gssapi_response: no authentication context"); 782 gssctxt = authctxt->methoddata; 783 784 /* Setup our OID */ 785 oidv = packet_get_string(&oidlen); 786 787 if (oidlen <= 2 || 788 oidv[0] != SSH_GSS_OIDTYPE || 789 oidv[1] != oidlen - 2) { 790 xfree(oidv); 791 debug("Badly encoded mechanism OID received"); 792 userauth(authctxt, NULL); 793 return; 794 } 795 796 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 797 fatal("Server returned different OID than expected"); 798 799 packet_check_eom(); 800 801 xfree(oidv); 802 803 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 804 /* Start again with next method on list */ 805 debug("Trying to start again"); 806 userauth(authctxt, NULL); 807 return; 808 } 809 } 810 811 /* ARGSUSED */ 812 void 813 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 814 { 815 Authctxt *authctxt = ctxt; 816 gss_buffer_desc recv_tok; 817 OM_uint32 status; 818 u_int slen; 819 820 if (authctxt == NULL) 821 fatal("input_gssapi_response: no authentication context"); 822 823 recv_tok.value = packet_get_string(&slen); 824 recv_tok.length = slen; /* safe typecast */ 825 826 packet_check_eom(); 827 828 status = process_gssapi_token(ctxt, &recv_tok); 829 830 xfree(recv_tok.value); 831 832 if (GSS_ERROR(status)) { 833 /* Start again with the next method in the list */ 834 userauth(authctxt, NULL); 835 return; 836 } 837 } 838 839 /* ARGSUSED */ 840 void 841 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 842 { 843 Authctxt *authctxt = ctxt; 844 Gssctxt *gssctxt; 845 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 846 gss_buffer_desc recv_tok; 847 OM_uint32 status, ms; 848 u_int len; 849 850 if (authctxt == NULL) 851 fatal("input_gssapi_response: no authentication context"); 852 gssctxt = authctxt->methoddata; 853 854 recv_tok.value = packet_get_string(&len); 855 recv_tok.length = len; 856 857 packet_check_eom(); 858 859 /* Stick it into GSSAPI and see what it says */ 860 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 861 &recv_tok, &send_tok, NULL); 862 863 xfree(recv_tok.value); 864 gss_release_buffer(&ms, &send_tok); 865 866 /* Server will be returning a failed packet after this one */ 867 } 868 869 /* ARGSUSED */ 870 void 871 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 872 { 873 OM_uint32 maj, min; 874 char *msg; 875 char *lang; 876 877 maj=packet_get_int(); 878 min=packet_get_int(); 879 msg=packet_get_string(NULL); 880 lang=packet_get_string(NULL); 881 882 packet_check_eom(); 883 884 debug("Server GSSAPI Error:\n%s", msg); 885 xfree(msg); 886 xfree(lang); 887 } 888 #endif /* GSSAPI */ 889 890 int 891 userauth_none(Authctxt *authctxt) 892 { 893 /* initial userauth request */ 894 packet_start(SSH2_MSG_USERAUTH_REQUEST); 895 packet_put_cstring(authctxt->server_user); 896 packet_put_cstring(authctxt->service); 897 packet_put_cstring(authctxt->method->name); 898 packet_send(); 899 return 1; 900 } 901 902 int 903 userauth_passwd(Authctxt *authctxt) 904 { 905 static int attempt = 0; 906 char prompt[150]; 907 char *password; 908 const char *host = options.host_key_alias ? options.host_key_alias : 909 authctxt->host; 910 911 if (attempt++ >= options.number_of_password_prompts) 912 return 0; 913 914 if (attempt != 1) 915 error("Permission denied, please try again."); 916 917 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 918 authctxt->server_user, host); 919 password = read_passphrase(prompt, 0); 920 packet_start(SSH2_MSG_USERAUTH_REQUEST); 921 packet_put_cstring(authctxt->server_user); 922 packet_put_cstring(authctxt->service); 923 packet_put_cstring(authctxt->method->name); 924 packet_put_char(0); 925 packet_put_cstring(password); 926 memset(password, 0, strlen(password)); 927 xfree(password); 928 packet_add_padding(64); 929 packet_send(); 930 931 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 932 &input_userauth_passwd_changereq); 933 934 return 1; 935 } 936 937 /* 938 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 939 */ 940 /* ARGSUSED */ 941 void 942 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 943 { 944 Authctxt *authctxt = ctxt; 945 char *info, *lang, *password = NULL, *retype = NULL; 946 char prompt[150]; 947 const char *host = options.host_key_alias ? options.host_key_alias : 948 authctxt->host; 949 950 debug2("input_userauth_passwd_changereq"); 951 952 if (authctxt == NULL) 953 fatal("input_userauth_passwd_changereq: " 954 "no authentication context"); 955 956 info = packet_get_string(NULL); 957 lang = packet_get_string(NULL); 958 if (strlen(info) > 0) 959 logit("%s", info); 960 xfree(info); 961 xfree(lang); 962 packet_start(SSH2_MSG_USERAUTH_REQUEST); 963 packet_put_cstring(authctxt->server_user); 964 packet_put_cstring(authctxt->service); 965 packet_put_cstring(authctxt->method->name); 966 packet_put_char(1); /* additional info */ 967 snprintf(prompt, sizeof(prompt), 968 "Enter %.30s@%.128s's old password: ", 969 authctxt->server_user, host); 970 password = read_passphrase(prompt, 0); 971 packet_put_cstring(password); 972 memset(password, 0, strlen(password)); 973 xfree(password); 974 password = NULL; 975 while (password == NULL) { 976 snprintf(prompt, sizeof(prompt), 977 "Enter %.30s@%.128s's new password: ", 978 authctxt->server_user, host); 979 password = read_passphrase(prompt, RP_ALLOW_EOF); 980 if (password == NULL) { 981 /* bail out */ 982 return; 983 } 984 snprintf(prompt, sizeof(prompt), 985 "Retype %.30s@%.128s's new password: ", 986 authctxt->server_user, host); 987 retype = read_passphrase(prompt, 0); 988 if (strcmp(password, retype) != 0) { 989 memset(password, 0, strlen(password)); 990 xfree(password); 991 logit("Mismatch; try again, EOF to quit."); 992 password = NULL; 993 } 994 memset(retype, 0, strlen(retype)); 995 xfree(retype); 996 } 997 packet_put_cstring(password); 998 memset(password, 0, strlen(password)); 999 xfree(password); 1000 packet_add_padding(64); 1001 packet_send(); 1002 1003 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1004 &input_userauth_passwd_changereq); 1005 } 1006 1007 #ifdef JPAKE 1008 static char * 1009 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 1010 { 1011 /* OpenBSD crypt(3) handles all of these */ 1012 if (strcmp(crypt_scheme, "crypt") == 0 || 1013 strcmp(crypt_scheme, "bcrypt") == 0 || 1014 strcmp(crypt_scheme, "md5crypt") == 0 || 1015 strcmp(crypt_scheme, "crypt-extended") == 0) 1016 return xstrdup(crypt(password, salt)); 1017 error("%s: unsupported password encryption scheme \"%.100s\"", 1018 __func__, crypt_scheme); 1019 return NULL; 1020 } 1021 1022 static BIGNUM * 1023 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 1024 const char *salt) 1025 { 1026 char prompt[256], *password, *crypted; 1027 u_char *secret; 1028 u_int secret_len; 1029 BIGNUM *ret; 1030 1031 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 1032 authctxt->server_user, authctxt->host); 1033 password = read_passphrase(prompt, 0); 1034 1035 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 1036 logit("Disabling %s authentication", authctxt->method->name); 1037 authctxt->method->enabled = NULL; 1038 /* Continue with an empty password to fail gracefully */ 1039 crypted = xstrdup(""); 1040 } 1041 1042 #ifdef JPAKE_DEBUG 1043 debug3("%s: salt = %s", __func__, salt); 1044 debug3("%s: scheme = %s", __func__, crypt_scheme); 1045 debug3("%s: crypted = %s", __func__, crypted); 1046 #endif 1047 1048 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 1049 &secret, &secret_len) != 0) 1050 fatal("%s: hash_buffer", __func__); 1051 1052 bzero(password, strlen(password)); 1053 bzero(crypted, strlen(crypted)); 1054 xfree(password); 1055 xfree(crypted); 1056 1057 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1058 fatal("%s: BN_bin2bn (secret)", __func__); 1059 bzero(secret, secret_len); 1060 xfree(secret); 1061 1062 return ret; 1063 } 1064 1065 /* ARGSUSED */ 1066 void 1067 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1068 { 1069 Authctxt *authctxt = ctxt; 1070 struct jpake_ctx *pctx = authctxt->methoddata; 1071 u_char *x3_proof, *x4_proof, *x2_s_proof; 1072 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1073 char *crypt_scheme, *salt; 1074 1075 /* Disable this message */ 1076 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1077 1078 if ((pctx->g_x3 = BN_new()) == NULL || 1079 (pctx->g_x4 = BN_new()) == NULL) 1080 fatal("%s: BN_new", __func__); 1081 1082 /* Fetch step 1 values */ 1083 crypt_scheme = packet_get_string(NULL); 1084 salt = packet_get_string(NULL); 1085 pctx->server_id = packet_get_string(&pctx->server_id_len); 1086 packet_get_bignum2(pctx->g_x3); 1087 packet_get_bignum2(pctx->g_x4); 1088 x3_proof = packet_get_string(&x3_proof_len); 1089 x4_proof = packet_get_string(&x4_proof_len); 1090 packet_check_eom(); 1091 1092 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1093 1094 /* Obtain password and derive secret */ 1095 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1096 bzero(crypt_scheme, strlen(crypt_scheme)); 1097 bzero(salt, strlen(salt)); 1098 xfree(crypt_scheme); 1099 xfree(salt); 1100 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1101 1102 /* Calculate step 2 values */ 1103 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1104 pctx->g_x3, pctx->g_x4, pctx->x2, 1105 pctx->server_id, pctx->server_id_len, 1106 pctx->client_id, pctx->client_id_len, 1107 x3_proof, x3_proof_len, 1108 x4_proof, x4_proof_len, 1109 &pctx->a, 1110 &x2_s_proof, &x2_s_proof_len); 1111 1112 bzero(x3_proof, x3_proof_len); 1113 bzero(x4_proof, x4_proof_len); 1114 xfree(x3_proof); 1115 xfree(x4_proof); 1116 1117 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1118 1119 /* Send values for step 2 */ 1120 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1121 packet_put_bignum2(pctx->a); 1122 packet_put_string(x2_s_proof, x2_s_proof_len); 1123 packet_send(); 1124 1125 bzero(x2_s_proof, x2_s_proof_len); 1126 xfree(x2_s_proof); 1127 1128 /* Expect step 2 packet from peer */ 1129 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1130 input_userauth_jpake_server_step2); 1131 } 1132 1133 /* ARGSUSED */ 1134 void 1135 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1136 { 1137 Authctxt *authctxt = ctxt; 1138 struct jpake_ctx *pctx = authctxt->methoddata; 1139 u_char *x4_s_proof; 1140 u_int x4_s_proof_len; 1141 1142 /* Disable this message */ 1143 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1144 1145 if ((pctx->b = BN_new()) == NULL) 1146 fatal("%s: BN_new", __func__); 1147 1148 /* Fetch step 2 values */ 1149 packet_get_bignum2(pctx->b); 1150 x4_s_proof = packet_get_string(&x4_s_proof_len); 1151 packet_check_eom(); 1152 1153 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1154 1155 /* Derive shared key and calculate confirmation hash */ 1156 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1157 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1158 pctx->client_id, pctx->client_id_len, 1159 pctx->server_id, pctx->server_id_len, 1160 session_id2, session_id2_len, 1161 x4_s_proof, x4_s_proof_len, 1162 &pctx->k, 1163 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1164 1165 bzero(x4_s_proof, x4_s_proof_len); 1166 xfree(x4_s_proof); 1167 1168 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1169 1170 /* Send key confirmation proof */ 1171 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1172 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1173 packet_send(); 1174 1175 /* Expect confirmation from peer */ 1176 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1177 input_userauth_jpake_server_confirm); 1178 } 1179 1180 /* ARGSUSED */ 1181 void 1182 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1183 { 1184 Authctxt *authctxt = ctxt; 1185 struct jpake_ctx *pctx = authctxt->methoddata; 1186 1187 /* Disable this message */ 1188 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1189 1190 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1191 packet_check_eom(); 1192 1193 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1194 1195 /* Verify expected confirmation hash */ 1196 if (jpake_check_confirm(pctx->k, 1197 pctx->server_id, pctx->server_id_len, 1198 session_id2, session_id2_len, 1199 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1200 debug("%s: %s success", __func__, authctxt->method->name); 1201 else { 1202 debug("%s: confirmation mismatch", __func__); 1203 /* XXX stash this so if auth succeeds then we can warn/kill */ 1204 } 1205 1206 userauth_jpake_cleanup(authctxt); 1207 } 1208 #endif /* JPAKE */ 1209 1210 static int 1211 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1212 u_char *data, u_int datalen) 1213 { 1214 Key *prv; 1215 int ret; 1216 1217 /* the agent supports this key */ 1218 if (id->ac) 1219 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1220 data, datalen)); 1221 /* 1222 * we have already loaded the private key or 1223 * the private key is stored in external hardware 1224 */ 1225 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1226 return (key_sign(id->key, sigp, lenp, data, datalen)); 1227 /* load the private key from the file */ 1228 if ((prv = load_identity_file(id->filename)) == NULL) 1229 return (-1); 1230 ret = key_sign(prv, sigp, lenp, data, datalen); 1231 key_free(prv); 1232 return (ret); 1233 } 1234 1235 static int 1236 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1237 { 1238 Buffer b; 1239 u_char *blob, *signature; 1240 u_int bloblen, slen; 1241 u_int skip = 0; 1242 int ret = -1; 1243 int have_sig = 1; 1244 char *fp; 1245 1246 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1247 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1248 xfree(fp); 1249 1250 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1251 /* we cannot handle this key */ 1252 debug3("sign_and_send_pubkey: cannot handle key"); 1253 return 0; 1254 } 1255 /* data to be signed */ 1256 buffer_init(&b); 1257 if (datafellows & SSH_OLD_SESSIONID) { 1258 buffer_append(&b, session_id2, session_id2_len); 1259 skip = session_id2_len; 1260 } else { 1261 buffer_put_string(&b, session_id2, session_id2_len); 1262 skip = buffer_len(&b); 1263 } 1264 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1265 buffer_put_cstring(&b, authctxt->server_user); 1266 buffer_put_cstring(&b, 1267 datafellows & SSH_BUG_PKSERVICE ? 1268 "ssh-userauth" : 1269 authctxt->service); 1270 if (datafellows & SSH_BUG_PKAUTH) { 1271 buffer_put_char(&b, have_sig); 1272 } else { 1273 buffer_put_cstring(&b, authctxt->method->name); 1274 buffer_put_char(&b, have_sig); 1275 buffer_put_cstring(&b, key_ssh_name(id->key)); 1276 } 1277 buffer_put_string(&b, blob, bloblen); 1278 1279 /* generate signature */ 1280 ret = identity_sign(id, &signature, &slen, 1281 buffer_ptr(&b), buffer_len(&b)); 1282 if (ret == -1) { 1283 xfree(blob); 1284 buffer_free(&b); 1285 return 0; 1286 } 1287 #ifdef DEBUG_PK 1288 buffer_dump(&b); 1289 #endif 1290 if (datafellows & SSH_BUG_PKSERVICE) { 1291 buffer_clear(&b); 1292 buffer_append(&b, session_id2, session_id2_len); 1293 skip = session_id2_len; 1294 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1295 buffer_put_cstring(&b, authctxt->server_user); 1296 buffer_put_cstring(&b, authctxt->service); 1297 buffer_put_cstring(&b, authctxt->method->name); 1298 buffer_put_char(&b, have_sig); 1299 if (!(datafellows & SSH_BUG_PKAUTH)) 1300 buffer_put_cstring(&b, key_ssh_name(id->key)); 1301 buffer_put_string(&b, blob, bloblen); 1302 } 1303 xfree(blob); 1304 1305 /* append signature */ 1306 buffer_put_string(&b, signature, slen); 1307 xfree(signature); 1308 1309 /* skip session id and packet type */ 1310 if (buffer_len(&b) < skip + 1) 1311 fatal("userauth_pubkey: internal error"); 1312 buffer_consume(&b, skip + 1); 1313 1314 /* put remaining data from buffer into packet */ 1315 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1316 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1317 buffer_free(&b); 1318 packet_send(); 1319 1320 return 1; 1321 } 1322 1323 static int 1324 send_pubkey_test(Authctxt *authctxt, Identity *id) 1325 { 1326 u_char *blob; 1327 u_int bloblen, have_sig = 0; 1328 1329 debug3("send_pubkey_test"); 1330 1331 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1332 /* we cannot handle this key */ 1333 debug3("send_pubkey_test: cannot handle key"); 1334 return 0; 1335 } 1336 /* register callback for USERAUTH_PK_OK message */ 1337 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1338 1339 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1340 packet_put_cstring(authctxt->server_user); 1341 packet_put_cstring(authctxt->service); 1342 packet_put_cstring(authctxt->method->name); 1343 packet_put_char(have_sig); 1344 if (!(datafellows & SSH_BUG_PKAUTH)) 1345 packet_put_cstring(key_ssh_name(id->key)); 1346 packet_put_string(blob, bloblen); 1347 xfree(blob); 1348 packet_send(); 1349 return 1; 1350 } 1351 1352 static Key * 1353 load_identity_file(char *filename) 1354 { 1355 Key *private; 1356 char prompt[300], *passphrase; 1357 int perm_ok = 0, quit, i; 1358 struct stat st; 1359 1360 if (stat(filename, &st) < 0) { 1361 debug3("no such identity: %s", filename); 1362 return NULL; 1363 } 1364 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1365 if (!perm_ok) 1366 return NULL; 1367 if (private == NULL) { 1368 if (options.batch_mode) 1369 return NULL; 1370 snprintf(prompt, sizeof prompt, 1371 "Enter passphrase for key '%.100s': ", filename); 1372 for (i = 0; i < options.number_of_password_prompts; i++) { 1373 passphrase = read_passphrase(prompt, 0); 1374 if (strcmp(passphrase, "") != 0) { 1375 private = key_load_private_type(KEY_UNSPEC, 1376 filename, passphrase, NULL, NULL); 1377 quit = 0; 1378 } else { 1379 debug2("no passphrase given, try next key"); 1380 quit = 1; 1381 } 1382 memset(passphrase, 0, strlen(passphrase)); 1383 xfree(passphrase); 1384 if (private != NULL || quit) 1385 break; 1386 debug2("bad passphrase given, try again..."); 1387 } 1388 } 1389 return private; 1390 } 1391 1392 /* 1393 * try keys in the following order: 1394 * 1. agent keys that are found in the config file 1395 * 2. other agent keys 1396 * 3. keys that are only listed in the config file 1397 */ 1398 static void 1399 pubkey_prepare(Authctxt *authctxt) 1400 { 1401 Identity *id; 1402 Idlist agent, files, *preferred; 1403 Key *key; 1404 AuthenticationConnection *ac; 1405 char *comment; 1406 int i, found; 1407 1408 TAILQ_INIT(&agent); /* keys from the agent */ 1409 TAILQ_INIT(&files); /* keys from the config file */ 1410 preferred = &authctxt->keys; 1411 TAILQ_INIT(preferred); /* preferred order of keys */ 1412 1413 /* list of keys stored in the filesystem */ 1414 for (i = 0; i < options.num_identity_files; i++) { 1415 key = options.identity_keys[i]; 1416 if (key && key->type == KEY_RSA1) 1417 continue; 1418 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1419 continue; 1420 options.identity_keys[i] = NULL; 1421 id = xcalloc(1, sizeof(*id)); 1422 id->key = key; 1423 id->filename = xstrdup(options.identity_files[i]); 1424 TAILQ_INSERT_TAIL(&files, id, next); 1425 } 1426 /* list of keys supported by the agent */ 1427 if ((ac = ssh_get_authentication_connection())) { 1428 for (key = ssh_get_first_identity(ac, &comment, 2); 1429 key != NULL; 1430 key = ssh_get_next_identity(ac, &comment, 2)) { 1431 found = 0; 1432 TAILQ_FOREACH(id, &files, next) { 1433 /* agent keys from the config file are preferred */ 1434 if (key_equal(key, id->key)) { 1435 key_free(key); 1436 xfree(comment); 1437 TAILQ_REMOVE(&files, id, next); 1438 TAILQ_INSERT_TAIL(preferred, id, next); 1439 id->ac = ac; 1440 found = 1; 1441 break; 1442 } 1443 } 1444 if (!found && !options.identities_only) { 1445 id = xcalloc(1, sizeof(*id)); 1446 id->key = key; 1447 id->filename = comment; 1448 id->ac = ac; 1449 TAILQ_INSERT_TAIL(&agent, id, next); 1450 } 1451 } 1452 /* append remaining agent keys */ 1453 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1454 TAILQ_REMOVE(&agent, id, next); 1455 TAILQ_INSERT_TAIL(preferred, id, next); 1456 } 1457 authctxt->agent = ac; 1458 } 1459 /* append remaining keys from the config file */ 1460 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1461 TAILQ_REMOVE(&files, id, next); 1462 TAILQ_INSERT_TAIL(preferred, id, next); 1463 } 1464 TAILQ_FOREACH(id, preferred, next) { 1465 debug2("key: %s (%p)", id->filename, id->key); 1466 } 1467 } 1468 1469 static void 1470 pubkey_cleanup(Authctxt *authctxt) 1471 { 1472 Identity *id; 1473 1474 if (authctxt->agent != NULL) 1475 ssh_close_authentication_connection(authctxt->agent); 1476 for (id = TAILQ_FIRST(&authctxt->keys); id; 1477 id = TAILQ_FIRST(&authctxt->keys)) { 1478 TAILQ_REMOVE(&authctxt->keys, id, next); 1479 if (id->key) 1480 key_free(id->key); 1481 if (id->filename) 1482 xfree(id->filename); 1483 xfree(id); 1484 } 1485 } 1486 1487 int 1488 userauth_pubkey(Authctxt *authctxt) 1489 { 1490 Identity *id; 1491 int sent = 0; 1492 1493 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1494 if (id->tried++) 1495 return (0); 1496 /* move key to the end of the queue */ 1497 TAILQ_REMOVE(&authctxt->keys, id, next); 1498 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1499 /* 1500 * send a test message if we have the public key. for 1501 * encrypted keys we cannot do this and have to load the 1502 * private key instead 1503 */ 1504 if (id->key && id->key->type != KEY_RSA1) { 1505 debug("Offering %s public key: %s", key_type(id->key), 1506 id->filename); 1507 sent = send_pubkey_test(authctxt, id); 1508 } else if (id->key == NULL) { 1509 debug("Trying private key: %s", id->filename); 1510 id->key = load_identity_file(id->filename); 1511 if (id->key != NULL) { 1512 id->isprivate = 1; 1513 sent = sign_and_send_pubkey(authctxt, id); 1514 key_free(id->key); 1515 id->key = NULL; 1516 } 1517 } 1518 if (sent) 1519 return (sent); 1520 } 1521 return (0); 1522 } 1523 1524 /* 1525 * Send userauth request message specifying keyboard-interactive method. 1526 */ 1527 int 1528 userauth_kbdint(Authctxt *authctxt) 1529 { 1530 static int attempt = 0; 1531 1532 if (attempt++ >= options.number_of_password_prompts) 1533 return 0; 1534 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1535 if (attempt > 1 && !authctxt->info_req_seen) { 1536 debug3("userauth_kbdint: disable: no info_req_seen"); 1537 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1538 return 0; 1539 } 1540 1541 debug2("userauth_kbdint"); 1542 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1543 packet_put_cstring(authctxt->server_user); 1544 packet_put_cstring(authctxt->service); 1545 packet_put_cstring(authctxt->method->name); 1546 packet_put_cstring(""); /* lang */ 1547 packet_put_cstring(options.kbd_interactive_devices ? 1548 options.kbd_interactive_devices : ""); 1549 packet_send(); 1550 1551 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1552 return 1; 1553 } 1554 1555 /* 1556 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1557 */ 1558 void 1559 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1560 { 1561 Authctxt *authctxt = ctxt; 1562 char *name, *inst, *lang, *prompt, *response; 1563 u_int num_prompts, i; 1564 int echo = 0; 1565 1566 debug2("input_userauth_info_req"); 1567 1568 if (authctxt == NULL) 1569 fatal("input_userauth_info_req: no authentication context"); 1570 1571 authctxt->info_req_seen = 1; 1572 1573 name = packet_get_string(NULL); 1574 inst = packet_get_string(NULL); 1575 lang = packet_get_string(NULL); 1576 if (strlen(name) > 0) 1577 logit("%s", name); 1578 if (strlen(inst) > 0) 1579 logit("%s", inst); 1580 xfree(name); 1581 xfree(inst); 1582 xfree(lang); 1583 1584 num_prompts = packet_get_int(); 1585 /* 1586 * Begin to build info response packet based on prompts requested. 1587 * We commit to providing the correct number of responses, so if 1588 * further on we run into a problem that prevents this, we have to 1589 * be sure and clean this up and send a correct error response. 1590 */ 1591 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1592 packet_put_int(num_prompts); 1593 1594 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1595 for (i = 0; i < num_prompts; i++) { 1596 prompt = packet_get_string(NULL); 1597 echo = packet_get_char(); 1598 1599 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1600 1601 packet_put_cstring(response); 1602 memset(response, 0, strlen(response)); 1603 xfree(response); 1604 xfree(prompt); 1605 } 1606 packet_check_eom(); /* done with parsing incoming message. */ 1607 1608 packet_add_padding(64); 1609 packet_send(); 1610 } 1611 1612 static int 1613 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1614 u_char *data, u_int datalen) 1615 { 1616 Buffer b; 1617 struct stat st; 1618 pid_t pid; 1619 int to[2], from[2], status, version = 2; 1620 1621 debug2("ssh_keysign called"); 1622 1623 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1624 error("ssh_keysign: not installed: %s", strerror(errno)); 1625 return -1; 1626 } 1627 if (fflush(stdout) != 0) 1628 error("ssh_keysign: fflush: %s", strerror(errno)); 1629 if (pipe(to) < 0) { 1630 error("ssh_keysign: pipe: %s", strerror(errno)); 1631 return -1; 1632 } 1633 if (pipe(from) < 0) { 1634 error("ssh_keysign: pipe: %s", strerror(errno)); 1635 return -1; 1636 } 1637 if ((pid = fork()) < 0) { 1638 error("ssh_keysign: fork: %s", strerror(errno)); 1639 return -1; 1640 } 1641 if (pid == 0) { 1642 /* keep the socket on exec */ 1643 fcntl(packet_get_connection_in(), F_SETFD, 0); 1644 permanently_drop_suid(getuid()); 1645 close(from[0]); 1646 if (dup2(from[1], STDOUT_FILENO) < 0) 1647 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1648 close(to[1]); 1649 if (dup2(to[0], STDIN_FILENO) < 0) 1650 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1651 close(from[1]); 1652 close(to[0]); 1653 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1654 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1655 strerror(errno)); 1656 } 1657 close(from[1]); 1658 close(to[0]); 1659 1660 buffer_init(&b); 1661 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1662 buffer_put_string(&b, data, datalen); 1663 if (ssh_msg_send(to[1], version, &b) == -1) 1664 fatal("ssh_keysign: couldn't send request"); 1665 1666 if (ssh_msg_recv(from[0], &b) < 0) { 1667 error("ssh_keysign: no reply"); 1668 buffer_free(&b); 1669 return -1; 1670 } 1671 close(from[0]); 1672 close(to[1]); 1673 1674 while (waitpid(pid, &status, 0) < 0) 1675 if (errno != EINTR) 1676 break; 1677 1678 if (buffer_get_char(&b) != version) { 1679 error("ssh_keysign: bad version"); 1680 buffer_free(&b); 1681 return -1; 1682 } 1683 *sigp = buffer_get_string(&b, lenp); 1684 buffer_free(&b); 1685 1686 return 0; 1687 } 1688 1689 int 1690 userauth_hostbased(Authctxt *authctxt) 1691 { 1692 Key *private = NULL; 1693 Sensitive *sensitive = authctxt->sensitive; 1694 Buffer b; 1695 u_char *signature, *blob; 1696 char *chost, *pkalg, *p; 1697 const char *service; 1698 u_int blen, slen; 1699 int ok, i, found = 0; 1700 1701 /* check for a useful key */ 1702 for (i = 0; i < sensitive->nkeys; i++) { 1703 private = sensitive->keys[i]; 1704 if (private && private->type != KEY_RSA1) { 1705 found = 1; 1706 /* we take and free the key */ 1707 sensitive->keys[i] = NULL; 1708 break; 1709 } 1710 } 1711 if (!found) { 1712 debug("No more client hostkeys for hostbased authentication."); 1713 return 0; 1714 } 1715 if (key_to_blob(private, &blob, &blen) == 0) { 1716 key_free(private); 1717 return 0; 1718 } 1719 /* figure out a name for the client host */ 1720 p = get_local_name(packet_get_connection_in()); 1721 if (p == NULL) { 1722 error("userauth_hostbased: cannot get local ipaddr/name"); 1723 key_free(private); 1724 xfree(blob); 1725 return 0; 1726 } 1727 xasprintf(&chost, "%s.", p); 1728 debug2("userauth_hostbased: chost %s", chost); 1729 xfree(p); 1730 1731 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1732 authctxt->service; 1733 pkalg = xstrdup(key_ssh_name(private)); 1734 buffer_init(&b); 1735 /* construct data */ 1736 buffer_put_string(&b, session_id2, session_id2_len); 1737 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1738 buffer_put_cstring(&b, authctxt->server_user); 1739 buffer_put_cstring(&b, service); 1740 buffer_put_cstring(&b, authctxt->method->name); 1741 buffer_put_cstring(&b, pkalg); 1742 buffer_put_string(&b, blob, blen); 1743 buffer_put_cstring(&b, chost); 1744 buffer_put_cstring(&b, authctxt->local_user); 1745 #ifdef DEBUG_PK 1746 buffer_dump(&b); 1747 #endif 1748 if (sensitive->external_keysign) 1749 ok = ssh_keysign(private, &signature, &slen, 1750 buffer_ptr(&b), buffer_len(&b)); 1751 else 1752 ok = key_sign(private, &signature, &slen, 1753 buffer_ptr(&b), buffer_len(&b)); 1754 key_free(private); 1755 buffer_free(&b); 1756 if (ok != 0) { 1757 error("key_sign failed"); 1758 xfree(chost); 1759 xfree(pkalg); 1760 xfree(blob); 1761 return 0; 1762 } 1763 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1764 packet_put_cstring(authctxt->server_user); 1765 packet_put_cstring(authctxt->service); 1766 packet_put_cstring(authctxt->method->name); 1767 packet_put_cstring(pkalg); 1768 packet_put_string(blob, blen); 1769 packet_put_cstring(chost); 1770 packet_put_cstring(authctxt->local_user); 1771 packet_put_string(signature, slen); 1772 memset(signature, 's', slen); 1773 xfree(signature); 1774 xfree(chost); 1775 xfree(pkalg); 1776 xfree(blob); 1777 1778 packet_send(); 1779 return 1; 1780 } 1781 1782 #ifdef JPAKE 1783 int 1784 userauth_jpake(Authctxt *authctxt) 1785 { 1786 struct jpake_ctx *pctx; 1787 u_char *x1_proof, *x2_proof; 1788 u_int x1_proof_len, x2_proof_len; 1789 static int attempt = 0; /* XXX share with userauth_password's? */ 1790 1791 if (attempt++ >= options.number_of_password_prompts) 1792 return 0; 1793 if (attempt != 1) 1794 error("Permission denied, please try again."); 1795 1796 if (authctxt->methoddata != NULL) 1797 fatal("%s: authctxt->methoddata already set (%p)", 1798 __func__, authctxt->methoddata); 1799 1800 authctxt->methoddata = pctx = jpake_new(); 1801 1802 /* 1803 * Send request immediately, to get the protocol going while 1804 * we do the initial computations. 1805 */ 1806 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1807 packet_put_cstring(authctxt->server_user); 1808 packet_put_cstring(authctxt->service); 1809 packet_put_cstring(authctxt->method->name); 1810 packet_send(); 1811 packet_write_wait(); 1812 1813 jpake_step1(pctx->grp, 1814 &pctx->client_id, &pctx->client_id_len, 1815 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1816 &x1_proof, &x1_proof_len, 1817 &x2_proof, &x2_proof_len); 1818 1819 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1820 1821 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1822 packet_put_string(pctx->client_id, pctx->client_id_len); 1823 packet_put_bignum2(pctx->g_x1); 1824 packet_put_bignum2(pctx->g_x2); 1825 packet_put_string(x1_proof, x1_proof_len); 1826 packet_put_string(x2_proof, x2_proof_len); 1827 packet_send(); 1828 1829 bzero(x1_proof, x1_proof_len); 1830 bzero(x2_proof, x2_proof_len); 1831 xfree(x1_proof); 1832 xfree(x2_proof); 1833 1834 /* Expect step 1 packet from peer */ 1835 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1836 input_userauth_jpake_server_step1); 1837 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1838 &input_userauth_success_unexpected); 1839 1840 return 1; 1841 } 1842 1843 void 1844 userauth_jpake_cleanup(Authctxt *authctxt) 1845 { 1846 debug3("%s: clean up", __func__); 1847 if (authctxt->methoddata != NULL) { 1848 jpake_free(authctxt->methoddata); 1849 authctxt->methoddata = NULL; 1850 } 1851 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1852 } 1853 #endif /* JPAKE */ 1854 1855 #if KRB5 1856 static int 1857 ssh_krb5_helper(krb5_data *ap) 1858 { 1859 krb5_context xcontext = NULL; /* XXX share with ssh1 */ 1860 krb5_auth_context xauth_context = NULL; 1861 1862 krb5_context *context; 1863 krb5_auth_context *auth_context; 1864 krb5_error_code problem; 1865 const char *tkfile; 1866 struct stat buf; 1867 krb5_ccache ccache = NULL; 1868 const char *remotehost; 1869 int ret; 1870 const char *errtxt; 1871 1872 memset(ap, 0, sizeof(*ap)); 1873 1874 context = &xcontext; 1875 auth_context = &xauth_context; 1876 1877 problem = krb5_init_context(context); 1878 if (problem) { 1879 debug("Kerberos v5: krb5_init_context failed"); 1880 ret = 0; 1881 goto out; 1882 } 1883 1884 tkfile = krb5_cc_default_name(*context); 1885 if (strncmp(tkfile, "FILE:", 5) == 0) 1886 tkfile += 5; 1887 1888 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 1889 debug("Kerberos v5: could not get default ccache (permission denied)."); 1890 ret = 0; 1891 goto out; 1892 } 1893 1894 problem = krb5_cc_default(*context, &ccache); 1895 if (problem) { 1896 errtxt = krb5_get_error_message(*context, problem); 1897 if (errtxt != NULL) { 1898 debug("Kerberos v5: krb5_cc_default failed: %s", 1899 errtxt); 1900 krb5_free_error_message(*context, errtxt); 1901 } else 1902 debug("Kerberos v5: krb5_cc_default failed: %d", 1903 problem); 1904 ret = 0; 1905 goto out; 1906 } 1907 1908 remotehost = get_canonical_hostname(1); 1909 1910 problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, 1911 "host", remotehost, NULL, ccache, ap); 1912 if (problem) { 1913 errtxt = krb5_get_error_message(*context, problem); 1914 if (errtxt != NULL) { 1915 debug("Kerberos v5: krb5_mk_req failed: %s", errtxt); 1916 krb5_free_error_message(*context, errtxt); 1917 } else 1918 debug("Kerberos v5: krb5_mk_req failed: %d", problem); 1919 ret = 0; 1920 goto out; 1921 } 1922 ret = 1; 1923 1924 out: 1925 if (ccache != NULL) 1926 krb5_cc_close(*context, ccache); 1927 if (*auth_context) 1928 krb5_auth_con_free(*context, *auth_context); 1929 if (*context) 1930 krb5_free_context(*context); 1931 return (ret); 1932 } 1933 1934 int 1935 userauth_kerberos(Authctxt *authctxt) 1936 { 1937 krb5_data ap; 1938 1939 if (ssh_krb5_helper(&ap) == 0) 1940 return (0); 1941 1942 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1943 packet_put_cstring(authctxt->server_user); 1944 packet_put_cstring(authctxt->service); 1945 packet_put_cstring(authctxt->method->name); 1946 packet_put_string(ap.data, ap.length); 1947 packet_send(); 1948 1949 krb5_data_free(&ap); 1950 return (1); 1951 } 1952 #endif 1953 1954 /* find auth method */ 1955 1956 /* 1957 * given auth method name, if configurable options permit this method fill 1958 * in auth_ident field and return true, otherwise return false. 1959 */ 1960 static int 1961 authmethod_is_enabled(Authmethod *method) 1962 { 1963 if (method == NULL) 1964 return 0; 1965 /* return false if options indicate this method is disabled */ 1966 if (method->enabled == NULL || *method->enabled == 0) 1967 return 0; 1968 /* return false if batch mode is enabled but method needs interactive mode */ 1969 if (method->batch_flag != NULL && *method->batch_flag != 0) 1970 return 0; 1971 return 1; 1972 } 1973 1974 static Authmethod * 1975 authmethod_lookup(const char *name) 1976 { 1977 Authmethod *method = NULL; 1978 if (name != NULL) 1979 for (method = authmethods; method->name != NULL; method++) 1980 if (strcmp(name, method->name) == 0) 1981 return method; 1982 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1983 return NULL; 1984 } 1985 1986 /* XXX internal state */ 1987 static Authmethod *current = NULL; 1988 static char *supported = NULL; 1989 static char *preferred = NULL; 1990 1991 /* 1992 * Given the authentication method list sent by the server, return the 1993 * next method we should try. If the server initially sends a nil list, 1994 * use a built-in default list. 1995 */ 1996 static Authmethod * 1997 authmethod_get(char *authlist) 1998 { 1999 char *name = NULL; 2000 u_int next; 2001 2002 /* Use a suitable default if we're passed a nil list. */ 2003 if (authlist == NULL || strlen(authlist) == 0) 2004 authlist = options.preferred_authentications; 2005 2006 if (supported == NULL || strcmp(authlist, supported) != 0) { 2007 debug3("start over, passed a different list %s", authlist); 2008 if (supported != NULL) 2009 xfree(supported); 2010 supported = xstrdup(authlist); 2011 preferred = options.preferred_authentications; 2012 debug3("preferred %s", preferred); 2013 current = NULL; 2014 } else if (current != NULL && authmethod_is_enabled(current)) 2015 return current; 2016 2017 for (;;) { 2018 if ((name = match_list(preferred, supported, &next)) == NULL) { 2019 debug("No more authentication methods to try."); 2020 current = NULL; 2021 return NULL; 2022 } 2023 preferred += next; 2024 debug3("authmethod_lookup %s", name); 2025 debug3("remaining preferred: %s", preferred); 2026 if ((current = authmethod_lookup(name)) != NULL && 2027 authmethod_is_enabled(current)) { 2028 debug3("authmethod_is_enabled %s", name); 2029 debug("Next authentication method: %s", name); 2030 xfree(name); 2031 return current; 2032 } 2033 } 2034 } 2035 2036 static char * 2037 authmethods_get(void) 2038 { 2039 Authmethod *method = NULL; 2040 Buffer b; 2041 char *list; 2042 2043 buffer_init(&b); 2044 for (method = authmethods; method->name != NULL; method++) { 2045 if (authmethod_is_enabled(method)) { 2046 if (buffer_len(&b) > 0) 2047 buffer_append(&b, ",", 1); 2048 buffer_append(&b, method->name, strlen(method->name)); 2049 } 2050 } 2051 buffer_append(&b, "\0", 1); 2052 list = xstrdup(buffer_ptr(&b)); 2053 buffer_free(&b); 2054 return list; 2055 } 2056 2057