sshconnect2.c revision 137019
1/* 2 * Copyright (c) 2000 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25#include "includes.h" 26RCSID("$OpenBSD: sshconnect2.c,v 1.138 2004/06/13 12:53:24 djm Exp $"); 27 28#include "openbsd-compat/sys-queue.h" 29 30#include "ssh.h" 31#include "ssh2.h" 32#include "xmalloc.h" 33#include "buffer.h" 34#include "packet.h" 35#include "compat.h" 36#include "bufaux.h" 37#include "cipher.h" 38#include "kex.h" 39#include "myproposal.h" 40#include "sshconnect.h" 41#include "authfile.h" 42#include "dh.h" 43#include "authfd.h" 44#include "log.h" 45#include "readconf.h" 46#include "misc.h" 47#include "match.h" 48#include "dispatch.h" 49#include "canohost.h" 50#include "msg.h" 51#include "pathnames.h" 52 53#ifdef GSSAPI 54#include "ssh-gss.h" 55#endif 56 57/* import */ 58extern char *client_version_string; 59extern char *server_version_string; 60extern Options options; 61 62/* 63 * SSH2 key exchange 64 */ 65 66u_char *session_id2 = NULL; 67u_int session_id2_len = 0; 68 69char *xxx_host; 70struct sockaddr *xxx_hostaddr; 71 72Kex *xxx_kex = NULL; 73 74static int 75verify_host_key_callback(Key *hostkey) 76{ 77 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 78 fatal("Host key verification failed."); 79 return 0; 80} 81 82void 83ssh_kex2(char *host, struct sockaddr *hostaddr) 84{ 85 Kex *kex; 86 87 xxx_host = host; 88 xxx_hostaddr = hostaddr; 89 90 if (options.ciphers == (char *)-1) { 91 logit("No valid ciphers for protocol version 2 given, using defaults."); 92 options.ciphers = NULL; 93 } 94 if (options.ciphers != NULL) { 95 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 96 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 97 } 98 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 99 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 100 myproposal[PROPOSAL_ENC_ALGS_STOC] = 101 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 102 if (options.compression) { 103 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 104 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none"; 105 } else { 106 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 107 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib"; 108 } 109 if (options.macs != NULL) { 110 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 111 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 112 } 113 if (options.hostkeyalgorithms != NULL) 114 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 115 options.hostkeyalgorithms; 116 117 if (options.rekey_limit) 118 packet_set_rekey_limit(options.rekey_limit); 119 120 /* start key exchange */ 121 kex = kex_setup(myproposal); 122 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 123 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 124 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 125 kex->client_version_string=client_version_string; 126 kex->server_version_string=server_version_string; 127 kex->verify_host_key=&verify_host_key_callback; 128 129 xxx_kex = kex; 130 131 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 132 133 session_id2 = kex->session_id; 134 session_id2_len = kex->session_id_len; 135 136#ifdef DEBUG_KEXDH 137 /* send 1st encrypted/maced/compressed message */ 138 packet_start(SSH2_MSG_IGNORE); 139 packet_put_cstring("markus"); 140 packet_send(); 141 packet_write_wait(); 142#endif 143} 144 145/* 146 * Authenticate user 147 */ 148 149typedef struct Authctxt Authctxt; 150typedef struct Authmethod Authmethod; 151typedef struct identity Identity; 152typedef struct idlist Idlist; 153 154struct identity { 155 TAILQ_ENTRY(identity) next; 156 AuthenticationConnection *ac; /* set if agent supports key */ 157 Key *key; /* public/private key */ 158 char *filename; /* comment for agent-only keys */ 159 int tried; 160 int isprivate; /* key points to the private key */ 161}; 162TAILQ_HEAD(idlist, identity); 163 164struct Authctxt { 165 const char *server_user; 166 const char *local_user; 167 const char *host; 168 const char *service; 169 Authmethod *method; 170 int success; 171 char *authlist; 172 /* pubkey */ 173 Idlist keys; 174 AuthenticationConnection *agent; 175 /* hostbased */ 176 Sensitive *sensitive; 177 /* kbd-interactive */ 178 int info_req_seen; 179 /* generic */ 180 void *methoddata; 181}; 182struct Authmethod { 183 char *name; /* string to compare against server's list */ 184 int (*userauth)(Authctxt *authctxt); 185 int *enabled; /* flag in option struct that enables method */ 186 int *batch_flag; /* flag in option struct that disables method */ 187}; 188 189void input_userauth_success(int, u_int32_t, void *); 190void input_userauth_failure(int, u_int32_t, void *); 191void input_userauth_banner(int, u_int32_t, void *); 192void input_userauth_error(int, u_int32_t, void *); 193void input_userauth_info_req(int, u_int32_t, void *); 194void input_userauth_pk_ok(int, u_int32_t, void *); 195void input_userauth_passwd_changereq(int, u_int32_t, void *); 196 197int userauth_none(Authctxt *); 198int userauth_pubkey(Authctxt *); 199int userauth_passwd(Authctxt *); 200int userauth_kbdint(Authctxt *); 201int userauth_hostbased(Authctxt *); 202int userauth_kerberos(Authctxt *); 203 204#ifdef GSSAPI 205int userauth_gssapi(Authctxt *authctxt); 206void input_gssapi_response(int type, u_int32_t, void *); 207void input_gssapi_token(int type, u_int32_t, void *); 208void input_gssapi_hash(int type, u_int32_t, void *); 209void input_gssapi_error(int, u_int32_t, void *); 210void input_gssapi_errtok(int, u_int32_t, void *); 211#endif 212 213void userauth(Authctxt *, char *); 214 215static int sign_and_send_pubkey(Authctxt *, Identity *); 216static void pubkey_prepare(Authctxt *); 217static void pubkey_cleanup(Authctxt *); 218static Key *load_identity_file(char *); 219 220static Authmethod *authmethod_get(char *authlist); 221static Authmethod *authmethod_lookup(const char *name); 222static char *authmethods_get(void); 223 224Authmethod authmethods[] = { 225#ifdef GSSAPI 226 {"gssapi-with-mic", 227 userauth_gssapi, 228 &options.gss_authentication, 229 NULL}, 230#endif 231 {"hostbased", 232 userauth_hostbased, 233 &options.hostbased_authentication, 234 NULL}, 235 {"publickey", 236 userauth_pubkey, 237 &options.pubkey_authentication, 238 NULL}, 239 {"keyboard-interactive", 240 userauth_kbdint, 241 &options.kbd_interactive_authentication, 242 &options.batch_mode}, 243 {"password", 244 userauth_passwd, 245 &options.password_authentication, 246 &options.batch_mode}, 247 {"none", 248 userauth_none, 249 NULL, 250 NULL}, 251 {NULL, NULL, NULL, NULL} 252}; 253 254void 255ssh_userauth2(const char *local_user, const char *server_user, char *host, 256 Sensitive *sensitive) 257{ 258 Authctxt authctxt; 259 int type; 260 261 if (options.challenge_response_authentication) 262 options.kbd_interactive_authentication = 1; 263 264 packet_start(SSH2_MSG_SERVICE_REQUEST); 265 packet_put_cstring("ssh-userauth"); 266 packet_send(); 267 debug("SSH2_MSG_SERVICE_REQUEST sent"); 268 packet_write_wait(); 269 type = packet_read(); 270 if (type != SSH2_MSG_SERVICE_ACCEPT) 271 fatal("Server denied authentication request: %d", type); 272 if (packet_remaining() > 0) { 273 char *reply = packet_get_string(NULL); 274 debug2("service_accept: %s", reply); 275 xfree(reply); 276 } else { 277 debug2("buggy server: service_accept w/o service"); 278 } 279 packet_check_eom(); 280 debug("SSH2_MSG_SERVICE_ACCEPT received"); 281 282 if (options.preferred_authentications == NULL) 283 options.preferred_authentications = authmethods_get(); 284 285 /* setup authentication context */ 286 memset(&authctxt, 0, sizeof(authctxt)); 287 pubkey_prepare(&authctxt); 288 authctxt.server_user = server_user; 289 authctxt.local_user = local_user; 290 authctxt.host = host; 291 authctxt.service = "ssh-connection"; /* service name */ 292 authctxt.success = 0; 293 authctxt.method = authmethod_lookup("none"); 294 authctxt.authlist = NULL; 295 authctxt.methoddata = NULL; 296 authctxt.sensitive = sensitive; 297 authctxt.info_req_seen = 0; 298 if (authctxt.method == NULL) 299 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 300 301 /* initial userauth request */ 302 userauth_none(&authctxt); 303 304 dispatch_init(&input_userauth_error); 305 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 306 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 307 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 308 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 309 310 pubkey_cleanup(&authctxt); 311 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 312 313 debug("Authentication succeeded (%s).", authctxt.method->name); 314} 315 316void 317userauth(Authctxt *authctxt, char *authlist) 318{ 319 if (authctxt->methoddata) { 320 xfree(authctxt->methoddata); 321 authctxt->methoddata = NULL; 322 } 323 if (authlist == NULL) { 324 authlist = authctxt->authlist; 325 } else { 326 if (authctxt->authlist) 327 xfree(authctxt->authlist); 328 authctxt->authlist = authlist; 329 } 330 for (;;) { 331 Authmethod *method = authmethod_get(authlist); 332 if (method == NULL) 333 fatal("Permission denied (%s).", authlist); 334 authctxt->method = method; 335 336 /* reset the per method handler */ 337 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 338 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 339 340 /* and try new method */ 341 if (method->userauth(authctxt) != 0) { 342 debug2("we sent a %s packet, wait for reply", method->name); 343 break; 344 } else { 345 debug2("we did not send a packet, disable method"); 346 method->enabled = NULL; 347 } 348 } 349} 350 351void 352input_userauth_error(int type, u_int32_t seq, void *ctxt) 353{ 354 fatal("input_userauth_error: bad message during authentication: " 355 "type %d", type); 356} 357 358void 359input_userauth_banner(int type, u_int32_t seq, void *ctxt) 360{ 361 char *msg, *lang; 362 363 debug3("input_userauth_banner"); 364 msg = packet_get_string(NULL); 365 lang = packet_get_string(NULL); 366 if (options.log_level > SYSLOG_LEVEL_QUIET) 367 fprintf(stderr, "%s", msg); 368 xfree(msg); 369 xfree(lang); 370} 371 372void 373input_userauth_success(int type, u_int32_t seq, void *ctxt) 374{ 375 Authctxt *authctxt = ctxt; 376 if (authctxt == NULL) 377 fatal("input_userauth_success: no authentication context"); 378 if (authctxt->authlist) { 379 xfree(authctxt->authlist); 380 authctxt->authlist = NULL; 381 } 382 if (authctxt->methoddata) { 383 xfree(authctxt->methoddata); 384 authctxt->methoddata = NULL; 385 } 386 authctxt->success = 1; /* break out */ 387} 388 389void 390input_userauth_failure(int type, u_int32_t seq, void *ctxt) 391{ 392 Authctxt *authctxt = ctxt; 393 char *authlist = NULL; 394 int partial; 395 396 if (authctxt == NULL) 397 fatal("input_userauth_failure: no authentication context"); 398 399 authlist = packet_get_string(NULL); 400 partial = packet_get_char(); 401 packet_check_eom(); 402 403 if (partial != 0) 404 logit("Authenticated with partial success."); 405 debug("Authentications that can continue: %s", authlist); 406 407 userauth(authctxt, authlist); 408} 409void 410input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 411{ 412 Authctxt *authctxt = ctxt; 413 Key *key = NULL; 414 Identity *id = NULL; 415 Buffer b; 416 int pktype, sent = 0; 417 u_int alen, blen; 418 char *pkalg, *fp; 419 u_char *pkblob; 420 421 if (authctxt == NULL) 422 fatal("input_userauth_pk_ok: no authentication context"); 423 if (datafellows & SSH_BUG_PKOK) { 424 /* this is similar to SSH_BUG_PKAUTH */ 425 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 426 pkblob = packet_get_string(&blen); 427 buffer_init(&b); 428 buffer_append(&b, pkblob, blen); 429 pkalg = buffer_get_string(&b, &alen); 430 buffer_free(&b); 431 } else { 432 pkalg = packet_get_string(&alen); 433 pkblob = packet_get_string(&blen); 434 } 435 packet_check_eom(); 436 437 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 438 439 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 440 debug("unknown pkalg %s", pkalg); 441 goto done; 442 } 443 if ((key = key_from_blob(pkblob, blen)) == NULL) { 444 debug("no key from blob. pkalg %s", pkalg); 445 goto done; 446 } 447 if (key->type != pktype) { 448 error("input_userauth_pk_ok: type mismatch " 449 "for decoded key (received %d, expected %d)", 450 key->type, pktype); 451 goto done; 452 } 453 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 454 debug2("input_userauth_pk_ok: fp %s", fp); 455 xfree(fp); 456 457 /* 458 * search keys in the reverse order, because last candidate has been 459 * moved to the end of the queue. this also avoids confusion by 460 * duplicate keys 461 */ 462 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 463 if (key_equal(key, id->key)) { 464 sent = sign_and_send_pubkey(authctxt, id); 465 break; 466 } 467 } 468done: 469 if (key != NULL) 470 key_free(key); 471 xfree(pkalg); 472 xfree(pkblob); 473 474 /* try another method if we did not send a packet */ 475 if (sent == 0) 476 userauth(authctxt, NULL); 477} 478 479#ifdef GSSAPI 480int 481userauth_gssapi(Authctxt *authctxt) 482{ 483 Gssctxt *gssctxt = NULL; 484 static gss_OID_set gss_supported = NULL; 485 static int mech = 0; 486 OM_uint32 min; 487 int ok = 0; 488 489 /* Try one GSSAPI method at a time, rather than sending them all at 490 * once. */ 491 492 if (gss_supported == NULL) 493 gss_indicate_mechs(&min, &gss_supported); 494 495 /* Check to see if the mechanism is usable before we offer it */ 496 while (mech < gss_supported->count && !ok) { 497 if (gssctxt) 498 ssh_gssapi_delete_ctx(&gssctxt); 499 ssh_gssapi_build_ctx(&gssctxt); 500 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]); 501 502 /* My DER encoding requires length<128 */ 503 if (gss_supported->elements[mech].length < 128 && 504 !GSS_ERROR(ssh_gssapi_import_name(gssctxt, 505 authctxt->host))) { 506 ok = 1; /* Mechanism works */ 507 } else { 508 mech++; 509 } 510 } 511 512 if (!ok) return 0; 513 514 authctxt->methoddata=(void *)gssctxt; 515 516 packet_start(SSH2_MSG_USERAUTH_REQUEST); 517 packet_put_cstring(authctxt->server_user); 518 packet_put_cstring(authctxt->service); 519 packet_put_cstring(authctxt->method->name); 520 521 packet_put_int(1); 522 523 packet_put_int((gss_supported->elements[mech].length) + 2); 524 packet_put_char(SSH_GSS_OIDTYPE); 525 packet_put_char(gss_supported->elements[mech].length); 526 packet_put_raw(gss_supported->elements[mech].elements, 527 gss_supported->elements[mech].length); 528 529 packet_send(); 530 531 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 532 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 533 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 534 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 535 536 mech++; /* Move along to next candidate */ 537 538 return 1; 539} 540 541static OM_uint32 542process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 543{ 544 Authctxt *authctxt = ctxt; 545 Gssctxt *gssctxt = authctxt->methoddata; 546 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 547 gss_buffer_desc gssbuf, mic; 548 OM_uint32 status, ms, flags; 549 Buffer b; 550 551 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 552 recv_tok, &send_tok, &flags); 553 554 if (send_tok.length > 0) { 555 if (GSS_ERROR(status)) 556 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 557 else 558 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 559 560 packet_put_string(send_tok.value, send_tok.length); 561 packet_send(); 562 gss_release_buffer(&ms, &send_tok); 563 } 564 565 if (status == GSS_S_COMPLETE) { 566 /* send either complete or MIC, depending on mechanism */ 567 if (!(flags & GSS_C_INTEG_FLAG)) { 568 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 569 packet_send(); 570 } else { 571 ssh_gssapi_buildmic(&b, authctxt->server_user, 572 authctxt->service, "gssapi-with-mic"); 573 574 gssbuf.value = buffer_ptr(&b); 575 gssbuf.length = buffer_len(&b); 576 577 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 578 579 if (!GSS_ERROR(status)) { 580 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 581 packet_put_string(mic.value, mic.length); 582 583 packet_send(); 584 } 585 586 buffer_free(&b); 587 gss_release_buffer(&ms, &mic); 588 } 589 } 590 591 return status; 592} 593 594void 595input_gssapi_response(int type, u_int32_t plen, void *ctxt) 596{ 597 Authctxt *authctxt = ctxt; 598 Gssctxt *gssctxt; 599 int oidlen; 600 char *oidv; 601 602 if (authctxt == NULL) 603 fatal("input_gssapi_response: no authentication context"); 604 gssctxt = authctxt->methoddata; 605 606 /* Setup our OID */ 607 oidv = packet_get_string(&oidlen); 608 609 if (oidlen <= 2 || 610 oidv[0] != SSH_GSS_OIDTYPE || 611 oidv[1] != oidlen - 2) { 612 xfree(oidv); 613 debug("Badly encoded mechanism OID received"); 614 userauth(authctxt, NULL); 615 return; 616 } 617 618 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 619 fatal("Server returned different OID than expected"); 620 621 packet_check_eom(); 622 623 xfree(oidv); 624 625 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 626 /* Start again with next method on list */ 627 debug("Trying to start again"); 628 userauth(authctxt, NULL); 629 return; 630 } 631} 632 633void 634input_gssapi_token(int type, u_int32_t plen, void *ctxt) 635{ 636 Authctxt *authctxt = ctxt; 637 gss_buffer_desc recv_tok; 638 OM_uint32 status; 639 u_int slen; 640 641 if (authctxt == NULL) 642 fatal("input_gssapi_response: no authentication context"); 643 644 recv_tok.value = packet_get_string(&slen); 645 recv_tok.length = slen; /* safe typecast */ 646 647 packet_check_eom(); 648 649 status = process_gssapi_token(ctxt, &recv_tok); 650 651 xfree(recv_tok.value); 652 653 if (GSS_ERROR(status)) { 654 /* Start again with the next method in the list */ 655 userauth(authctxt, NULL); 656 return; 657 } 658} 659 660void 661input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 662{ 663 Authctxt *authctxt = ctxt; 664 Gssctxt *gssctxt; 665 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 666 gss_buffer_desc recv_tok; 667 OM_uint32 status, ms; 668 u_int len; 669 670 if (authctxt == NULL) 671 fatal("input_gssapi_response: no authentication context"); 672 gssctxt = authctxt->methoddata; 673 674 recv_tok.value = packet_get_string(&len); 675 recv_tok.length = len; 676 677 packet_check_eom(); 678 679 /* Stick it into GSSAPI and see what it says */ 680 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 681 &recv_tok, &send_tok, NULL); 682 683 xfree(recv_tok.value); 684 gss_release_buffer(&ms, &send_tok); 685 686 /* Server will be returning a failed packet after this one */ 687} 688 689void 690input_gssapi_error(int type, u_int32_t plen, void *ctxt) 691{ 692 OM_uint32 maj, min; 693 char *msg; 694 char *lang; 695 696 maj=packet_get_int(); 697 min=packet_get_int(); 698 msg=packet_get_string(NULL); 699 lang=packet_get_string(NULL); 700 701 packet_check_eom(); 702 703 debug("Server GSSAPI Error:\n%s\n", msg); 704 xfree(msg); 705 xfree(lang); 706} 707#endif /* GSSAPI */ 708 709int 710userauth_none(Authctxt *authctxt) 711{ 712 /* initial userauth request */ 713 packet_start(SSH2_MSG_USERAUTH_REQUEST); 714 packet_put_cstring(authctxt->server_user); 715 packet_put_cstring(authctxt->service); 716 packet_put_cstring(authctxt->method->name); 717 packet_send(); 718 return 1; 719} 720 721int 722userauth_passwd(Authctxt *authctxt) 723{ 724 static int attempt = 0; 725 char prompt[150]; 726 char *password; 727 728 if (attempt++ >= options.number_of_password_prompts) 729 return 0; 730 731 if (attempt != 1) 732 error("Permission denied, please try again."); 733 734 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 735 authctxt->server_user, authctxt->host); 736 password = read_passphrase(prompt, 0); 737 packet_start(SSH2_MSG_USERAUTH_REQUEST); 738 packet_put_cstring(authctxt->server_user); 739 packet_put_cstring(authctxt->service); 740 packet_put_cstring(authctxt->method->name); 741 packet_put_char(0); 742 packet_put_cstring(password); 743 memset(password, 0, strlen(password)); 744 xfree(password); 745 packet_add_padding(64); 746 packet_send(); 747 748 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 749 &input_userauth_passwd_changereq); 750 751 return 1; 752} 753/* 754 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 755 */ 756void 757input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 758{ 759 Authctxt *authctxt = ctxt; 760 char *info, *lang, *password = NULL, *retype = NULL; 761 char prompt[150]; 762 763 debug2("input_userauth_passwd_changereq"); 764 765 if (authctxt == NULL) 766 fatal("input_userauth_passwd_changereq: " 767 "no authentication context"); 768 769 info = packet_get_string(NULL); 770 lang = packet_get_string(NULL); 771 if (strlen(info) > 0) 772 logit("%s", info); 773 xfree(info); 774 xfree(lang); 775 packet_start(SSH2_MSG_USERAUTH_REQUEST); 776 packet_put_cstring(authctxt->server_user); 777 packet_put_cstring(authctxt->service); 778 packet_put_cstring(authctxt->method->name); 779 packet_put_char(1); /* additional info */ 780 snprintf(prompt, sizeof(prompt), 781 "Enter %.30s@%.128s's old password: ", 782 authctxt->server_user, authctxt->host); 783 password = read_passphrase(prompt, 0); 784 packet_put_cstring(password); 785 memset(password, 0, strlen(password)); 786 xfree(password); 787 password = NULL; 788 while (password == NULL) { 789 snprintf(prompt, sizeof(prompt), 790 "Enter %.30s@%.128s's new password: ", 791 authctxt->server_user, authctxt->host); 792 password = read_passphrase(prompt, RP_ALLOW_EOF); 793 if (password == NULL) { 794 /* bail out */ 795 return; 796 } 797 snprintf(prompt, sizeof(prompt), 798 "Retype %.30s@%.128s's new password: ", 799 authctxt->server_user, authctxt->host); 800 retype = read_passphrase(prompt, 0); 801 if (strcmp(password, retype) != 0) { 802 memset(password, 0, strlen(password)); 803 xfree(password); 804 logit("Mismatch; try again, EOF to quit."); 805 password = NULL; 806 } 807 memset(retype, 0, strlen(retype)); 808 xfree(retype); 809 } 810 packet_put_cstring(password); 811 memset(password, 0, strlen(password)); 812 xfree(password); 813 packet_add_padding(64); 814 packet_send(); 815 816 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 817 &input_userauth_passwd_changereq); 818} 819 820static int 821identity_sign(Identity *id, u_char **sigp, u_int *lenp, 822 u_char *data, u_int datalen) 823{ 824 Key *prv; 825 int ret; 826 827 /* the agent supports this key */ 828 if (id->ac) 829 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 830 data, datalen)); 831 /* 832 * we have already loaded the private key or 833 * the private key is stored in external hardware 834 */ 835 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 836 return (key_sign(id->key, sigp, lenp, data, datalen)); 837 /* load the private key from the file */ 838 if ((prv = load_identity_file(id->filename)) == NULL) 839 return (-1); 840 ret = key_sign(prv, sigp, lenp, data, datalen); 841 key_free(prv); 842 return (ret); 843} 844 845static int 846sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 847{ 848 Buffer b; 849 u_char *blob, *signature; 850 u_int bloblen, slen; 851 u_int skip = 0; 852 int ret = -1; 853 int have_sig = 1; 854 855 debug3("sign_and_send_pubkey"); 856 857 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 858 /* we cannot handle this key */ 859 debug3("sign_and_send_pubkey: cannot handle key"); 860 return 0; 861 } 862 /* data to be signed */ 863 buffer_init(&b); 864 if (datafellows & SSH_OLD_SESSIONID) { 865 buffer_append(&b, session_id2, session_id2_len); 866 skip = session_id2_len; 867 } else { 868 buffer_put_string(&b, session_id2, session_id2_len); 869 skip = buffer_len(&b); 870 } 871 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 872 buffer_put_cstring(&b, authctxt->server_user); 873 buffer_put_cstring(&b, 874 datafellows & SSH_BUG_PKSERVICE ? 875 "ssh-userauth" : 876 authctxt->service); 877 if (datafellows & SSH_BUG_PKAUTH) { 878 buffer_put_char(&b, have_sig); 879 } else { 880 buffer_put_cstring(&b, authctxt->method->name); 881 buffer_put_char(&b, have_sig); 882 buffer_put_cstring(&b, key_ssh_name(id->key)); 883 } 884 buffer_put_string(&b, blob, bloblen); 885 886 /* generate signature */ 887 ret = identity_sign(id, &signature, &slen, 888 buffer_ptr(&b), buffer_len(&b)); 889 if (ret == -1) { 890 xfree(blob); 891 buffer_free(&b); 892 return 0; 893 } 894#ifdef DEBUG_PK 895 buffer_dump(&b); 896#endif 897 if (datafellows & SSH_BUG_PKSERVICE) { 898 buffer_clear(&b); 899 buffer_append(&b, session_id2, session_id2_len); 900 skip = session_id2_len; 901 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 902 buffer_put_cstring(&b, authctxt->server_user); 903 buffer_put_cstring(&b, authctxt->service); 904 buffer_put_cstring(&b, authctxt->method->name); 905 buffer_put_char(&b, have_sig); 906 if (!(datafellows & SSH_BUG_PKAUTH)) 907 buffer_put_cstring(&b, key_ssh_name(id->key)); 908 buffer_put_string(&b, blob, bloblen); 909 } 910 xfree(blob); 911 912 /* append signature */ 913 buffer_put_string(&b, signature, slen); 914 xfree(signature); 915 916 /* skip session id and packet type */ 917 if (buffer_len(&b) < skip + 1) 918 fatal("userauth_pubkey: internal error"); 919 buffer_consume(&b, skip + 1); 920 921 /* put remaining data from buffer into packet */ 922 packet_start(SSH2_MSG_USERAUTH_REQUEST); 923 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 924 buffer_free(&b); 925 packet_send(); 926 927 return 1; 928} 929 930static int 931send_pubkey_test(Authctxt *authctxt, Identity *id) 932{ 933 u_char *blob; 934 u_int bloblen, have_sig = 0; 935 936 debug3("send_pubkey_test"); 937 938 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 939 /* we cannot handle this key */ 940 debug3("send_pubkey_test: cannot handle key"); 941 return 0; 942 } 943 /* register callback for USERAUTH_PK_OK message */ 944 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 945 946 packet_start(SSH2_MSG_USERAUTH_REQUEST); 947 packet_put_cstring(authctxt->server_user); 948 packet_put_cstring(authctxt->service); 949 packet_put_cstring(authctxt->method->name); 950 packet_put_char(have_sig); 951 if (!(datafellows & SSH_BUG_PKAUTH)) 952 packet_put_cstring(key_ssh_name(id->key)); 953 packet_put_string(blob, bloblen); 954 xfree(blob); 955 packet_send(); 956 return 1; 957} 958 959static Key * 960load_identity_file(char *filename) 961{ 962 Key *private; 963 char prompt[300], *passphrase; 964 int quit, i; 965 struct stat st; 966 967 if (stat(filename, &st) < 0) { 968 debug3("no such identity: %s", filename); 969 return NULL; 970 } 971 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 972 if (private == NULL) { 973 if (options.batch_mode) 974 return NULL; 975 snprintf(prompt, sizeof prompt, 976 "Enter passphrase for key '%.100s': ", filename); 977 for (i = 0; i < options.number_of_password_prompts; i++) { 978 passphrase = read_passphrase(prompt, 0); 979 if (strcmp(passphrase, "") != 0) { 980 private = key_load_private_type(KEY_UNSPEC, filename, 981 passphrase, NULL); 982 quit = 0; 983 } else { 984 debug2("no passphrase given, try next key"); 985 quit = 1; 986 } 987 memset(passphrase, 0, strlen(passphrase)); 988 xfree(passphrase); 989 if (private != NULL || quit) 990 break; 991 debug2("bad passphrase given, try again..."); 992 } 993 } 994 return private; 995} 996 997/* 998 * try keys in the following order: 999 * 1. agent keys that are found in the config file 1000 * 2. other agent keys 1001 * 3. keys that are only listed in the config file 1002 */ 1003static void 1004pubkey_prepare(Authctxt *authctxt) 1005{ 1006 Identity *id; 1007 Idlist agent, files, *preferred; 1008 Key *key; 1009 AuthenticationConnection *ac; 1010 char *comment; 1011 int i, found; 1012 1013 TAILQ_INIT(&agent); /* keys from the agent */ 1014 TAILQ_INIT(&files); /* keys from the config file */ 1015 preferred = &authctxt->keys; 1016 TAILQ_INIT(preferred); /* preferred order of keys */ 1017 1018 /* list of keys stored in the filesystem */ 1019 for (i = 0; i < options.num_identity_files; i++) { 1020 key = options.identity_keys[i]; 1021 if (key && key->type == KEY_RSA1) 1022 continue; 1023 options.identity_keys[i] = NULL; 1024 id = xmalloc(sizeof(*id)); 1025 memset(id, 0, sizeof(*id)); 1026 id->key = key; 1027 id->filename = xstrdup(options.identity_files[i]); 1028 TAILQ_INSERT_TAIL(&files, id, next); 1029 } 1030 /* list of keys supported by the agent */ 1031 if ((ac = ssh_get_authentication_connection())) { 1032 for (key = ssh_get_first_identity(ac, &comment, 2); 1033 key != NULL; 1034 key = ssh_get_next_identity(ac, &comment, 2)) { 1035 found = 0; 1036 TAILQ_FOREACH(id, &files, next) { 1037 /* agent keys from the config file are preferred */ 1038 if (key_equal(key, id->key)) { 1039 key_free(key); 1040 xfree(comment); 1041 TAILQ_REMOVE(&files, id, next); 1042 TAILQ_INSERT_TAIL(preferred, id, next); 1043 id->ac = ac; 1044 found = 1; 1045 break; 1046 } 1047 } 1048 if (!found && !options.identities_only) { 1049 id = xmalloc(sizeof(*id)); 1050 memset(id, 0, sizeof(*id)); 1051 id->key = key; 1052 id->filename = comment; 1053 id->ac = ac; 1054 TAILQ_INSERT_TAIL(&agent, id, next); 1055 } 1056 } 1057 /* append remaining agent keys */ 1058 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1059 TAILQ_REMOVE(&agent, id, next); 1060 TAILQ_INSERT_TAIL(preferred, id, next); 1061 } 1062 authctxt->agent = ac; 1063 } 1064 /* append remaining keys from the config file */ 1065 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1066 TAILQ_REMOVE(&files, id, next); 1067 TAILQ_INSERT_TAIL(preferred, id, next); 1068 } 1069 TAILQ_FOREACH(id, preferred, next) { 1070 debug2("key: %s (%p)", id->filename, id->key); 1071 } 1072} 1073 1074static void 1075pubkey_cleanup(Authctxt *authctxt) 1076{ 1077 Identity *id; 1078 1079 if (authctxt->agent != NULL) 1080 ssh_close_authentication_connection(authctxt->agent); 1081 for (id = TAILQ_FIRST(&authctxt->keys); id; 1082 id = TAILQ_FIRST(&authctxt->keys)) { 1083 TAILQ_REMOVE(&authctxt->keys, id, next); 1084 if (id->key) 1085 key_free(id->key); 1086 if (id->filename) 1087 xfree(id->filename); 1088 xfree(id); 1089 } 1090} 1091 1092int 1093userauth_pubkey(Authctxt *authctxt) 1094{ 1095 Identity *id; 1096 int sent = 0; 1097 1098 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1099 if (id->tried++) 1100 return (0); 1101 /* move key to the end of the queue */ 1102 TAILQ_REMOVE(&authctxt->keys, id, next); 1103 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1104 /* 1105 * send a test message if we have the public key. for 1106 * encrypted keys we cannot do this and have to load the 1107 * private key instead 1108 */ 1109 if (id->key && id->key->type != KEY_RSA1) { 1110 debug("Offering public key: %s", id->filename); 1111 sent = send_pubkey_test(authctxt, id); 1112 } else if (id->key == NULL) { 1113 debug("Trying private key: %s", id->filename); 1114 id->key = load_identity_file(id->filename); 1115 if (id->key != NULL) { 1116 id->isprivate = 1; 1117 sent = sign_and_send_pubkey(authctxt, id); 1118 key_free(id->key); 1119 id->key = NULL; 1120 } 1121 } 1122 if (sent) 1123 return (sent); 1124 } 1125 return (0); 1126} 1127 1128/* 1129 * Send userauth request message specifying keyboard-interactive method. 1130 */ 1131int 1132userauth_kbdint(Authctxt *authctxt) 1133{ 1134 static int attempt = 0; 1135 1136 if (attempt++ >= options.number_of_password_prompts) 1137 return 0; 1138 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1139 if (attempt > 1 && !authctxt->info_req_seen) { 1140 debug3("userauth_kbdint: disable: no info_req_seen"); 1141 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1142 return 0; 1143 } 1144 1145 debug2("userauth_kbdint"); 1146 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1147 packet_put_cstring(authctxt->server_user); 1148 packet_put_cstring(authctxt->service); 1149 packet_put_cstring(authctxt->method->name); 1150 packet_put_cstring(""); /* lang */ 1151 packet_put_cstring(options.kbd_interactive_devices ? 1152 options.kbd_interactive_devices : ""); 1153 packet_send(); 1154 1155 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1156 return 1; 1157} 1158 1159/* 1160 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1161 */ 1162void 1163input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1164{ 1165 Authctxt *authctxt = ctxt; 1166 char *name, *inst, *lang, *prompt, *response; 1167 u_int num_prompts, i; 1168 int echo = 0; 1169 1170 debug2("input_userauth_info_req"); 1171 1172 if (authctxt == NULL) 1173 fatal("input_userauth_info_req: no authentication context"); 1174 1175 authctxt->info_req_seen = 1; 1176 1177 name = packet_get_string(NULL); 1178 inst = packet_get_string(NULL); 1179 lang = packet_get_string(NULL); 1180 if (strlen(name) > 0) 1181 logit("%s", name); 1182 if (strlen(inst) > 0) 1183 logit("%s", inst); 1184 xfree(name); 1185 xfree(inst); 1186 xfree(lang); 1187 1188 num_prompts = packet_get_int(); 1189 /* 1190 * Begin to build info response packet based on prompts requested. 1191 * We commit to providing the correct number of responses, so if 1192 * further on we run into a problem that prevents this, we have to 1193 * be sure and clean this up and send a correct error response. 1194 */ 1195 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1196 packet_put_int(num_prompts); 1197 1198 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1199 for (i = 0; i < num_prompts; i++) { 1200 prompt = packet_get_string(NULL); 1201 echo = packet_get_char(); 1202 1203 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1204 1205 packet_put_cstring(response); 1206 memset(response, 0, strlen(response)); 1207 xfree(response); 1208 xfree(prompt); 1209 } 1210 packet_check_eom(); /* done with parsing incoming message. */ 1211 1212 packet_add_padding(64); 1213 packet_send(); 1214} 1215 1216static int 1217ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1218 u_char *data, u_int datalen) 1219{ 1220 Buffer b; 1221 struct stat st; 1222 pid_t pid; 1223 int to[2], from[2], status, version = 2; 1224 1225 debug2("ssh_keysign called"); 1226 1227 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1228 error("ssh_keysign: no installed: %s", strerror(errno)); 1229 return -1; 1230 } 1231 if (fflush(stdout) != 0) 1232 error("ssh_keysign: fflush: %s", strerror(errno)); 1233 if (pipe(to) < 0) { 1234 error("ssh_keysign: pipe: %s", strerror(errno)); 1235 return -1; 1236 } 1237 if (pipe(from) < 0) { 1238 error("ssh_keysign: pipe: %s", strerror(errno)); 1239 return -1; 1240 } 1241 if ((pid = fork()) < 0) { 1242 error("ssh_keysign: fork: %s", strerror(errno)); 1243 return -1; 1244 } 1245 if (pid == 0) { 1246 seteuid(getuid()); 1247 setuid(getuid()); 1248 close(from[0]); 1249 if (dup2(from[1], STDOUT_FILENO) < 0) 1250 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1251 close(to[1]); 1252 if (dup2(to[0], STDIN_FILENO) < 0) 1253 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1254 close(from[1]); 1255 close(to[0]); 1256 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1257 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1258 strerror(errno)); 1259 } 1260 close(from[1]); 1261 close(to[0]); 1262 1263 buffer_init(&b); 1264 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1265 buffer_put_string(&b, data, datalen); 1266 if (ssh_msg_send(to[1], version, &b) == -1) 1267 fatal("ssh_keysign: couldn't send request"); 1268 1269 if (ssh_msg_recv(from[0], &b) < 0) { 1270 error("ssh_keysign: no reply"); 1271 buffer_free(&b); 1272 return -1; 1273 } 1274 close(from[0]); 1275 close(to[1]); 1276 1277 while (waitpid(pid, &status, 0) < 0) 1278 if (errno != EINTR) 1279 break; 1280 1281 if (buffer_get_char(&b) != version) { 1282 error("ssh_keysign: bad version"); 1283 buffer_free(&b); 1284 return -1; 1285 } 1286 *sigp = buffer_get_string(&b, lenp); 1287 buffer_free(&b); 1288 1289 return 0; 1290} 1291 1292int 1293userauth_hostbased(Authctxt *authctxt) 1294{ 1295 Key *private = NULL; 1296 Sensitive *sensitive = authctxt->sensitive; 1297 Buffer b; 1298 u_char *signature, *blob; 1299 char *chost, *pkalg, *p; 1300 const char *service; 1301 u_int blen, slen; 1302 int ok, i, len, found = 0; 1303 1304 /* check for a useful key */ 1305 for (i = 0; i < sensitive->nkeys; i++) { 1306 private = sensitive->keys[i]; 1307 if (private && private->type != KEY_RSA1) { 1308 found = 1; 1309 /* we take and free the key */ 1310 sensitive->keys[i] = NULL; 1311 break; 1312 } 1313 } 1314 if (!found) { 1315 debug("No more client hostkeys for hostbased authentication."); 1316 return 0; 1317 } 1318 if (key_to_blob(private, &blob, &blen) == 0) { 1319 key_free(private); 1320 return 0; 1321 } 1322 /* figure out a name for the client host */ 1323 p = get_local_name(packet_get_connection_in()); 1324 if (p == NULL) { 1325 error("userauth_hostbased: cannot get local ipaddr/name"); 1326 key_free(private); 1327 return 0; 1328 } 1329 len = strlen(p) + 2; 1330 chost = xmalloc(len); 1331 strlcpy(chost, p, len); 1332 strlcat(chost, ".", len); 1333 debug2("userauth_hostbased: chost %s", chost); 1334 xfree(p); 1335 1336 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1337 authctxt->service; 1338 pkalg = xstrdup(key_ssh_name(private)); 1339 buffer_init(&b); 1340 /* construct data */ 1341 buffer_put_string(&b, session_id2, session_id2_len); 1342 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1343 buffer_put_cstring(&b, authctxt->server_user); 1344 buffer_put_cstring(&b, service); 1345 buffer_put_cstring(&b, authctxt->method->name); 1346 buffer_put_cstring(&b, pkalg); 1347 buffer_put_string(&b, blob, blen); 1348 buffer_put_cstring(&b, chost); 1349 buffer_put_cstring(&b, authctxt->local_user); 1350#ifdef DEBUG_PK 1351 buffer_dump(&b); 1352#endif 1353 if (sensitive->external_keysign) 1354 ok = ssh_keysign(private, &signature, &slen, 1355 buffer_ptr(&b), buffer_len(&b)); 1356 else 1357 ok = key_sign(private, &signature, &slen, 1358 buffer_ptr(&b), buffer_len(&b)); 1359 key_free(private); 1360 buffer_free(&b); 1361 if (ok != 0) { 1362 error("key_sign failed"); 1363 xfree(chost); 1364 xfree(pkalg); 1365 return 0; 1366 } 1367 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1368 packet_put_cstring(authctxt->server_user); 1369 packet_put_cstring(authctxt->service); 1370 packet_put_cstring(authctxt->method->name); 1371 packet_put_cstring(pkalg); 1372 packet_put_string(blob, blen); 1373 packet_put_cstring(chost); 1374 packet_put_cstring(authctxt->local_user); 1375 packet_put_string(signature, slen); 1376 memset(signature, 's', slen); 1377 xfree(signature); 1378 xfree(chost); 1379 xfree(pkalg); 1380 1381 packet_send(); 1382 return 1; 1383} 1384 1385/* find auth method */ 1386 1387/* 1388 * given auth method name, if configurable options permit this method fill 1389 * in auth_ident field and return true, otherwise return false. 1390 */ 1391static int 1392authmethod_is_enabled(Authmethod *method) 1393{ 1394 if (method == NULL) 1395 return 0; 1396 /* return false if options indicate this method is disabled */ 1397 if (method->enabled == NULL || *method->enabled == 0) 1398 return 0; 1399 /* return false if batch mode is enabled but method needs interactive mode */ 1400 if (method->batch_flag != NULL && *method->batch_flag != 0) 1401 return 0; 1402 return 1; 1403} 1404 1405static Authmethod * 1406authmethod_lookup(const char *name) 1407{ 1408 Authmethod *method = NULL; 1409 if (name != NULL) 1410 for (method = authmethods; method->name != NULL; method++) 1411 if (strcmp(name, method->name) == 0) 1412 return method; 1413 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1414 return NULL; 1415} 1416 1417/* XXX internal state */ 1418static Authmethod *current = NULL; 1419static char *supported = NULL; 1420static char *preferred = NULL; 1421 1422/* 1423 * Given the authentication method list sent by the server, return the 1424 * next method we should try. If the server initially sends a nil list, 1425 * use a built-in default list. 1426 */ 1427static Authmethod * 1428authmethod_get(char *authlist) 1429{ 1430 char *name = NULL; 1431 u_int next; 1432 1433 /* Use a suitable default if we're passed a nil list. */ 1434 if (authlist == NULL || strlen(authlist) == 0) 1435 authlist = options.preferred_authentications; 1436 1437 if (supported == NULL || strcmp(authlist, supported) != 0) { 1438 debug3("start over, passed a different list %s", authlist); 1439 if (supported != NULL) 1440 xfree(supported); 1441 supported = xstrdup(authlist); 1442 preferred = options.preferred_authentications; 1443 debug3("preferred %s", preferred); 1444 current = NULL; 1445 } else if (current != NULL && authmethod_is_enabled(current)) 1446 return current; 1447 1448 for (;;) { 1449 if ((name = match_list(preferred, supported, &next)) == NULL) { 1450 debug("No more authentication methods to try."); 1451 current = NULL; 1452 return NULL; 1453 } 1454 preferred += next; 1455 debug3("authmethod_lookup %s", name); 1456 debug3("remaining preferred: %s", preferred); 1457 if ((current = authmethod_lookup(name)) != NULL && 1458 authmethod_is_enabled(current)) { 1459 debug3("authmethod_is_enabled %s", name); 1460 debug("Next authentication method: %s", name); 1461 return current; 1462 } 1463 } 1464} 1465 1466static char * 1467authmethods_get(void) 1468{ 1469 Authmethod *method = NULL; 1470 Buffer b; 1471 char *list; 1472 1473 buffer_init(&b); 1474 for (method = authmethods; method->name != NULL; method++) { 1475 if (authmethod_is_enabled(method)) { 1476 if (buffer_len(&b) > 0) 1477 buffer_append(&b, ",", 1); 1478 buffer_append(&b, method->name, strlen(method->name)); 1479 } 1480 } 1481 buffer_append(&b, "\0", 1); 1482 list = xstrdup(buffer_ptr(&b)); 1483 buffer_free(&b); 1484 return list; 1485} 1486