sshconnect2.c revision 124211
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 1.124 2003/08/25 10:33:33 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 "readpass.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_GEX_SHA1] = kexgex_client; 124 kex->client_version_string=client_version_string; 125 kex->server_version_string=server_version_string; 126 kex->verify_host_key=&verify_host_key_callback; 127 128 xxx_kex = kex; 129 130 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 131 132 session_id2 = kex->session_id; 133 session_id2_len = kex->session_id_len; 134 135#ifdef DEBUG_KEXDH 136 /* send 1st encrypted/maced/compressed message */ 137 packet_start(SSH2_MSG_IGNORE); 138 packet_put_cstring("markus"); 139 packet_send(); 140 packet_write_wait(); 141#endif 142} 143 144/* 145 * Authenticate user 146 */ 147 148typedef struct Authctxt Authctxt; 149typedef struct Authmethod Authmethod; 150typedef struct identity Identity; 151typedef struct idlist Idlist; 152 153struct identity { 154 TAILQ_ENTRY(identity) next; 155 AuthenticationConnection *ac; /* set if agent supports key */ 156 Key *key; /* public/private key */ 157 char *filename; /* comment for agent-only keys */ 158 int tried; 159 int isprivate; /* key points to the private key */ 160}; 161TAILQ_HEAD(idlist, identity); 162 163struct Authctxt { 164 const char *server_user; 165 const char *local_user; 166 const char *host; 167 const char *service; 168 Authmethod *method; 169 int success; 170 char *authlist; 171 /* pubkey */ 172 Idlist keys; 173 AuthenticationConnection *agent; 174 /* hostbased */ 175 Sensitive *sensitive; 176 /* kbd-interactive */ 177 int info_req_seen; 178 /* generic */ 179 void *methoddata; 180}; 181struct Authmethod { 182 char *name; /* string to compare against server's list */ 183 int (*userauth)(Authctxt *authctxt); 184 int *enabled; /* flag in option struct that enables method */ 185 int *batch_flag; /* flag in option struct that disables method */ 186}; 187 188void input_userauth_success(int, u_int32_t, void *); 189void input_userauth_failure(int, u_int32_t, void *); 190void input_userauth_banner(int, u_int32_t, void *); 191void input_userauth_error(int, u_int32_t, void *); 192void input_userauth_info_req(int, u_int32_t, void *); 193void input_userauth_pk_ok(int, u_int32_t, void *); 194void input_userauth_passwd_changereq(int, u_int32_t, void *); 195 196int userauth_none(Authctxt *); 197int userauth_pubkey(Authctxt *); 198int userauth_passwd(Authctxt *); 199int userauth_kbdint(Authctxt *); 200int userauth_hostbased(Authctxt *); 201int userauth_kerberos(Authctxt *); 202 203#ifdef GSSAPI 204int userauth_gssapi(Authctxt *authctxt); 205void input_gssapi_response(int type, u_int32_t, void *); 206void input_gssapi_token(int type, u_int32_t, void *); 207void input_gssapi_hash(int type, u_int32_t, void *); 208void input_gssapi_error(int, u_int32_t, void *); 209void input_gssapi_errtok(int, u_int32_t, void *); 210#endif 211 212void userauth(Authctxt *, char *); 213 214static int sign_and_send_pubkey(Authctxt *, Identity *); 215static void pubkey_prepare(Authctxt *); 216static void pubkey_cleanup(Authctxt *); 217static Key *load_identity_file(char *); 218 219static Authmethod *authmethod_get(char *authlist); 220static Authmethod *authmethod_lookup(const char *name); 221static char *authmethods_get(void); 222 223Authmethod authmethods[] = { 224#ifdef GSSAPI 225 {"gssapi", 226 userauth_gssapi, 227 &options.gss_authentication, 228 NULL}, 229#endif 230 {"hostbased", 231 userauth_hostbased, 232 &options.hostbased_authentication, 233 NULL}, 234 {"publickey", 235 userauth_pubkey, 236 &options.pubkey_authentication, 237 NULL}, 238 {"keyboard-interactive", 239 userauth_kbdint, 240 &options.kbd_interactive_authentication, 241 &options.batch_mode}, 242 {"password", 243 userauth_passwd, 244 &options.password_authentication, 245 &options.batch_mode}, 246 {"none", 247 userauth_none, 248 NULL, 249 NULL}, 250 {NULL, NULL, NULL, NULL} 251}; 252 253void 254ssh_userauth2(const char *local_user, const char *server_user, char *host, 255 Sensitive *sensitive) 256{ 257 Authctxt authctxt; 258 int type; 259 260 if (options.challenge_response_authentication) 261 options.kbd_interactive_authentication = 1; 262 263 packet_start(SSH2_MSG_SERVICE_REQUEST); 264 packet_put_cstring("ssh-userauth"); 265 packet_send(); 266 debug("SSH2_MSG_SERVICE_REQUEST sent"); 267 packet_write_wait(); 268 type = packet_read(); 269 if (type != SSH2_MSG_SERVICE_ACCEPT) 270 fatal("Server denied authentication request: %d", type); 271 if (packet_remaining() > 0) { 272 char *reply = packet_get_string(NULL); 273 debug2("service_accept: %s", reply); 274 xfree(reply); 275 } else { 276 debug2("buggy server: service_accept w/o service"); 277 } 278 packet_check_eom(); 279 debug("SSH2_MSG_SERVICE_ACCEPT received"); 280 281 if (options.preferred_authentications == NULL) 282 options.preferred_authentications = authmethods_get(); 283 284 /* setup authentication context */ 285 memset(&authctxt, 0, sizeof(authctxt)); 286 pubkey_prepare(&authctxt); 287 authctxt.server_user = server_user; 288 authctxt.local_user = local_user; 289 authctxt.host = host; 290 authctxt.service = "ssh-connection"; /* service name */ 291 authctxt.success = 0; 292 authctxt.method = authmethod_lookup("none"); 293 authctxt.authlist = NULL; 294 authctxt.methoddata = NULL; 295 authctxt.sensitive = sensitive; 296 authctxt.info_req_seen = 0; 297 if (authctxt.method == NULL) 298 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 299 300 /* initial userauth request */ 301 userauth_none(&authctxt); 302 303 dispatch_init(&input_userauth_error); 304 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 305 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 306 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 307 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 308 309 pubkey_cleanup(&authctxt); 310 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 311 312 debug("Authentication succeeded (%s).", authctxt.method->name); 313} 314 315void 316userauth(Authctxt *authctxt, char *authlist) 317{ 318 if (authctxt->methoddata) { 319 xfree(authctxt->methoddata); 320 authctxt->methoddata = NULL; 321 } 322 if (authlist == NULL) { 323 authlist = authctxt->authlist; 324 } else { 325 if (authctxt->authlist) 326 xfree(authctxt->authlist); 327 authctxt->authlist = authlist; 328 } 329 for (;;) { 330 Authmethod *method = authmethod_get(authlist); 331 if (method == NULL) 332 fatal("Permission denied (%s).", authlist); 333 authctxt->method = method; 334 335 /* reset the per method handler */ 336 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 337 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 338 339 /* and try new method */ 340 if (method->userauth(authctxt) != 0) { 341 debug2("we sent a %s packet, wait for reply", method->name); 342 break; 343 } else { 344 debug2("we did not send a packet, disable method"); 345 method->enabled = NULL; 346 } 347 } 348} 349 350void 351input_userauth_error(int type, u_int32_t seq, void *ctxt) 352{ 353 fatal("input_userauth_error: bad message during authentication: " 354 "type %d", type); 355} 356 357void 358input_userauth_banner(int type, u_int32_t seq, void *ctxt) 359{ 360 char *msg, *lang; 361 debug3("input_userauth_banner"); 362 msg = packet_get_string(NULL); 363 lang = packet_get_string(NULL); 364 logit("%s", msg); 365 xfree(msg); 366 xfree(lang); 367} 368 369void 370input_userauth_success(int type, u_int32_t seq, void *ctxt) 371{ 372 Authctxt *authctxt = ctxt; 373 if (authctxt == NULL) 374 fatal("input_userauth_success: no authentication context"); 375 if (authctxt->authlist) 376 xfree(authctxt->authlist); 377 if (authctxt->methoddata) 378 xfree(authctxt->methoddata); 379 authctxt->success = 1; /* break out */ 380} 381 382void 383input_userauth_failure(int type, u_int32_t seq, void *ctxt) 384{ 385 Authctxt *authctxt = ctxt; 386 char *authlist = NULL; 387 int partial; 388 389 if (authctxt == NULL) 390 fatal("input_userauth_failure: no authentication context"); 391 392 authlist = packet_get_string(NULL); 393 partial = packet_get_char(); 394 packet_check_eom(); 395 396 if (partial != 0) 397 logit("Authenticated with partial success."); 398 debug("Authentications that can continue: %s", authlist); 399 400 userauth(authctxt, authlist); 401} 402void 403input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 404{ 405 Authctxt *authctxt = ctxt; 406 Key *key = NULL; 407 Identity *id = NULL; 408 Buffer b; 409 int pktype, sent = 0; 410 u_int alen, blen; 411 char *pkalg, *fp; 412 u_char *pkblob; 413 414 if (authctxt == NULL) 415 fatal("input_userauth_pk_ok: no authentication context"); 416 if (datafellows & SSH_BUG_PKOK) { 417 /* this is similar to SSH_BUG_PKAUTH */ 418 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 419 pkblob = packet_get_string(&blen); 420 buffer_init(&b); 421 buffer_append(&b, pkblob, blen); 422 pkalg = buffer_get_string(&b, &alen); 423 buffer_free(&b); 424 } else { 425 pkalg = packet_get_string(&alen); 426 pkblob = packet_get_string(&blen); 427 } 428 packet_check_eom(); 429 430 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 431 432 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 433 debug("unknown pkalg %s", pkalg); 434 goto done; 435 } 436 if ((key = key_from_blob(pkblob, blen)) == NULL) { 437 debug("no key from blob. pkalg %s", pkalg); 438 goto done; 439 } 440 if (key->type != pktype) { 441 error("input_userauth_pk_ok: type mismatch " 442 "for decoded key (received %d, expected %d)", 443 key->type, pktype); 444 goto done; 445 } 446 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 447 debug2("input_userauth_pk_ok: fp %s", fp); 448 xfree(fp); 449 450 TAILQ_FOREACH(id, &authctxt->keys, next) { 451 if (key_equal(key, id->key)) { 452 sent = sign_and_send_pubkey(authctxt, id); 453 break; 454 } 455 } 456done: 457 if (key != NULL) 458 key_free(key); 459 xfree(pkalg); 460 xfree(pkblob); 461 462 /* try another method if we did not send a packet */ 463 if (sent == 0) 464 userauth(authctxt, NULL); 465} 466 467#ifdef GSSAPI 468int 469userauth_gssapi(Authctxt *authctxt) 470{ 471 Gssctxt *gssctxt = NULL; 472 static gss_OID_set supported = NULL; 473 static int mech = 0; 474 OM_uint32 min; 475 int ok = 0; 476 477 /* Try one GSSAPI method at a time, rather than sending them all at 478 * once. */ 479 480 if (supported == NULL) 481 gss_indicate_mechs(&min, &supported); 482 483 /* Check to see if the mechanism is usable before we offer it */ 484 while (mech<supported->count && !ok) { 485 if (gssctxt) 486 ssh_gssapi_delete_ctx(&gssctxt); 487 ssh_gssapi_build_ctx(&gssctxt); 488 ssh_gssapi_set_oid(gssctxt, &supported->elements[mech]); 489 490 /* My DER encoding requires length<128 */ 491 if (supported->elements[mech].length < 128 && 492 !GSS_ERROR(ssh_gssapi_import_name(gssctxt, 493 authctxt->host))) { 494 ok = 1; /* Mechanism works */ 495 } else { 496 mech++; 497 } 498 } 499 500 if (!ok) return 0; 501 502 authctxt->methoddata=(void *)gssctxt; 503 504 packet_start(SSH2_MSG_USERAUTH_REQUEST); 505 packet_put_cstring(authctxt->server_user); 506 packet_put_cstring(authctxt->service); 507 packet_put_cstring(authctxt->method->name); 508 509 packet_put_int(1); 510 511 /* Some servers encode the OID incorrectly (as we used to) */ 512 if (datafellows & SSH_BUG_GSSAPI_BER) { 513 packet_put_string(supported->elements[mech].elements, 514 supported->elements[mech].length); 515 } else { 516 packet_put_int((supported->elements[mech].length)+2); 517 packet_put_char(SSH_GSS_OIDTYPE); 518 packet_put_char(supported->elements[mech].length); 519 packet_put_raw(supported->elements[mech].elements, 520 supported->elements[mech].length); 521 } 522 523 packet_send(); 524 525 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 526 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 527 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 528 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 529 530 mech++; /* Move along to next candidate */ 531 532 return 1; 533} 534 535void 536input_gssapi_response(int type, u_int32_t plen, void *ctxt) 537{ 538 Authctxt *authctxt = ctxt; 539 Gssctxt *gssctxt; 540 OM_uint32 status, ms; 541 int oidlen; 542 char *oidv; 543 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 544 545 if (authctxt == NULL) 546 fatal("input_gssapi_response: no authentication context"); 547 gssctxt = authctxt->methoddata; 548 549 /* Setup our OID */ 550 oidv = packet_get_string(&oidlen); 551 552 if (datafellows & SSH_BUG_GSSAPI_BER) { 553 if (!ssh_gssapi_check_oid(gssctxt, oidv, oidlen)) 554 fatal("Server returned different OID than expected"); 555 } else { 556 if(oidv[0] != SSH_GSS_OIDTYPE || oidv[1] != oidlen-2) { 557 debug("Badly encoded mechanism OID received"); 558 userauth(authctxt, NULL); 559 xfree(oidv); 560 return; 561 } 562 if (!ssh_gssapi_check_oid(gssctxt, oidv+2, oidlen-2)) 563 fatal("Server returned different OID than expected"); 564 } 565 566 packet_check_eom(); 567 568 xfree(oidv); 569 570 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 571 GSS_C_NO_BUFFER, &send_tok, NULL); 572 if (GSS_ERROR(status)) { 573 if (send_tok.length > 0) { 574 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 575 packet_put_string(send_tok.value, send_tok.length); 576 packet_send(); 577 gss_release_buffer(&ms, &send_tok); 578 } 579 /* Start again with next method on list */ 580 debug("Trying to start again"); 581 userauth(authctxt, NULL); 582 return; 583 } 584 585 /* We must have data to send */ 586 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 587 packet_put_string(send_tok.value, send_tok.length); 588 packet_send(); 589 gss_release_buffer(&ms, &send_tok); 590} 591 592void 593input_gssapi_token(int type, u_int32_t plen, void *ctxt) 594{ 595 Authctxt *authctxt = ctxt; 596 Gssctxt *gssctxt; 597 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 598 gss_buffer_desc recv_tok; 599 OM_uint32 status, ms; 600 u_int slen; 601 602 if (authctxt == NULL) 603 fatal("input_gssapi_response: no authentication context"); 604 gssctxt = authctxt->methoddata; 605 606 recv_tok.value = packet_get_string(&slen); 607 recv_tok.length = slen; /* safe typecast */ 608 609 packet_check_eom(); 610 611 status=ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 612 &recv_tok, &send_tok, NULL); 613 614 xfree(recv_tok.value); 615 616 if (GSS_ERROR(status)) { 617 if (send_tok.length > 0) { 618 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 619 packet_put_string(send_tok.value, send_tok.length); 620 packet_send(); 621 gss_release_buffer(&ms, &send_tok); 622 } 623 /* Start again with the next method in the list */ 624 userauth(authctxt, NULL); 625 return; 626 } 627 628 if (send_tok.length > 0) { 629 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 630 packet_put_string(send_tok.value, send_tok.length); 631 packet_send(); 632 gss_release_buffer(&ms, &send_tok); 633 } 634 635 if (status == GSS_S_COMPLETE) { 636 /* If that succeeded, send a exchange complete message */ 637 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 638 packet_send(); 639 } 640} 641 642void 643input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 644{ 645 Authctxt *authctxt = ctxt; 646 Gssctxt *gssctxt; 647 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 648 gss_buffer_desc recv_tok; 649 OM_uint32 status, ms; 650 u_int len; 651 652 if (authctxt == NULL) 653 fatal("input_gssapi_response: no authentication context"); 654 gssctxt = authctxt->methoddata; 655 656 recv_tok.value = packet_get_string(&len); 657 recv_tok.length = len; 658 659 packet_check_eom(); 660 661 /* Stick it into GSSAPI and see what it says */ 662 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 663 &recv_tok, &send_tok, NULL); 664 665 xfree(recv_tok.value); 666 gss_release_buffer(&ms, &send_tok); 667 668 /* Server will be returning a failed packet after this one */ 669} 670 671void 672input_gssapi_error(int type, u_int32_t plen, void *ctxt) 673{ 674 OM_uint32 maj, min; 675 char *msg; 676 char *lang; 677 678 maj=packet_get_int(); 679 min=packet_get_int(); 680 msg=packet_get_string(NULL); 681 lang=packet_get_string(NULL); 682 683 packet_check_eom(); 684 685 debug("Server GSSAPI Error:\n%s\n", msg); 686 xfree(msg); 687 xfree(lang); 688} 689#endif /* GSSAPI */ 690 691int 692userauth_none(Authctxt *authctxt) 693{ 694 /* initial userauth request */ 695 packet_start(SSH2_MSG_USERAUTH_REQUEST); 696 packet_put_cstring(authctxt->server_user); 697 packet_put_cstring(authctxt->service); 698 packet_put_cstring(authctxt->method->name); 699 packet_send(); 700 return 1; 701} 702 703int 704userauth_passwd(Authctxt *authctxt) 705{ 706 static int attempt = 0; 707 char prompt[150]; 708 char *password; 709 710 if (attempt++ >= options.number_of_password_prompts) 711 return 0; 712 713 if (attempt != 1) 714 error("Permission denied, please try again."); 715 716 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 717 authctxt->server_user, authctxt->host); 718 password = read_passphrase(prompt, 0); 719 packet_start(SSH2_MSG_USERAUTH_REQUEST); 720 packet_put_cstring(authctxt->server_user); 721 packet_put_cstring(authctxt->service); 722 packet_put_cstring(authctxt->method->name); 723 packet_put_char(0); 724 packet_put_cstring(password); 725 memset(password, 0, strlen(password)); 726 xfree(password); 727 packet_add_padding(64); 728 packet_send(); 729 730 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 731 &input_userauth_passwd_changereq); 732 733 return 1; 734} 735/* 736 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 737 */ 738void 739input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 740{ 741 Authctxt *authctxt = ctxt; 742 char *info, *lang, *password = NULL, *retype = NULL; 743 char prompt[150]; 744 745 debug2("input_userauth_passwd_changereq"); 746 747 if (authctxt == NULL) 748 fatal("input_userauth_passwd_changereq: " 749 "no authentication context"); 750 751 info = packet_get_string(NULL); 752 lang = packet_get_string(NULL); 753 if (strlen(info) > 0) 754 logit("%s", info); 755 xfree(info); 756 xfree(lang); 757 packet_start(SSH2_MSG_USERAUTH_REQUEST); 758 packet_put_cstring(authctxt->server_user); 759 packet_put_cstring(authctxt->service); 760 packet_put_cstring(authctxt->method->name); 761 packet_put_char(1); /* additional info */ 762 snprintf(prompt, sizeof(prompt), 763 "Enter %.30s@%.128s's old password: ", 764 authctxt->server_user, authctxt->host); 765 password = read_passphrase(prompt, 0); 766 packet_put_cstring(password); 767 memset(password, 0, strlen(password)); 768 xfree(password); 769 password = NULL; 770 while (password == NULL) { 771 snprintf(prompt, sizeof(prompt), 772 "Enter %.30s@%.128s's new password: ", 773 authctxt->server_user, authctxt->host); 774 password = read_passphrase(prompt, RP_ALLOW_EOF); 775 if (password == NULL) { 776 /* bail out */ 777 return; 778 } 779 snprintf(prompt, sizeof(prompt), 780 "Retype %.30s@%.128s's new password: ", 781 authctxt->server_user, authctxt->host); 782 retype = read_passphrase(prompt, 0); 783 if (strcmp(password, retype) != 0) { 784 memset(password, 0, strlen(password)); 785 xfree(password); 786 logit("Mismatch; try again, EOF to quit."); 787 password = NULL; 788 } 789 memset(retype, 0, strlen(retype)); 790 xfree(retype); 791 } 792 packet_put_cstring(password); 793 memset(password, 0, strlen(password)); 794 xfree(password); 795 packet_add_padding(64); 796 packet_send(); 797 798 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 799 &input_userauth_passwd_changereq); 800} 801 802static int 803identity_sign(Identity *id, u_char **sigp, u_int *lenp, 804 u_char *data, u_int datalen) 805{ 806 Key *prv; 807 int ret; 808 809 /* the agent supports this key */ 810 if (id->ac) 811 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 812 data, datalen)); 813 /* 814 * we have already loaded the private key or 815 * the private key is stored in external hardware 816 */ 817 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 818 return (key_sign(id->key, sigp, lenp, data, datalen)); 819 /* load the private key from the file */ 820 if ((prv = load_identity_file(id->filename)) == NULL) 821 return (-1); 822 ret = key_sign(prv, sigp, lenp, data, datalen); 823 key_free(prv); 824 return (ret); 825} 826 827static int 828sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 829{ 830 Buffer b; 831 u_char *blob, *signature; 832 u_int bloblen, slen; 833 u_int skip = 0; 834 int ret = -1; 835 int have_sig = 1; 836 837 debug3("sign_and_send_pubkey"); 838 839 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 840 /* we cannot handle this key */ 841 debug3("sign_and_send_pubkey: cannot handle key"); 842 return 0; 843 } 844 /* data to be signed */ 845 buffer_init(&b); 846 if (datafellows & SSH_OLD_SESSIONID) { 847 buffer_append(&b, session_id2, session_id2_len); 848 skip = session_id2_len; 849 } else { 850 buffer_put_string(&b, session_id2, session_id2_len); 851 skip = buffer_len(&b); 852 } 853 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 854 buffer_put_cstring(&b, authctxt->server_user); 855 buffer_put_cstring(&b, 856 datafellows & SSH_BUG_PKSERVICE ? 857 "ssh-userauth" : 858 authctxt->service); 859 if (datafellows & SSH_BUG_PKAUTH) { 860 buffer_put_char(&b, have_sig); 861 } else { 862 buffer_put_cstring(&b, authctxt->method->name); 863 buffer_put_char(&b, have_sig); 864 buffer_put_cstring(&b, key_ssh_name(id->key)); 865 } 866 buffer_put_string(&b, blob, bloblen); 867 868 /* generate signature */ 869 ret = identity_sign(id, &signature, &slen, 870 buffer_ptr(&b), buffer_len(&b)); 871 if (ret == -1) { 872 xfree(blob); 873 buffer_free(&b); 874 return 0; 875 } 876#ifdef DEBUG_PK 877 buffer_dump(&b); 878#endif 879 if (datafellows & SSH_BUG_PKSERVICE) { 880 buffer_clear(&b); 881 buffer_append(&b, session_id2, session_id2_len); 882 skip = session_id2_len; 883 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 884 buffer_put_cstring(&b, authctxt->server_user); 885 buffer_put_cstring(&b, authctxt->service); 886 buffer_put_cstring(&b, authctxt->method->name); 887 buffer_put_char(&b, have_sig); 888 if (!(datafellows & SSH_BUG_PKAUTH)) 889 buffer_put_cstring(&b, key_ssh_name(id->key)); 890 buffer_put_string(&b, blob, bloblen); 891 } 892 xfree(blob); 893 894 /* append signature */ 895 buffer_put_string(&b, signature, slen); 896 xfree(signature); 897 898 /* skip session id and packet type */ 899 if (buffer_len(&b) < skip + 1) 900 fatal("userauth_pubkey: internal error"); 901 buffer_consume(&b, skip + 1); 902 903 /* put remaining data from buffer into packet */ 904 packet_start(SSH2_MSG_USERAUTH_REQUEST); 905 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 906 buffer_free(&b); 907 packet_send(); 908 909 return 1; 910} 911 912static int 913send_pubkey_test(Authctxt *authctxt, Identity *id) 914{ 915 u_char *blob; 916 u_int bloblen, have_sig = 0; 917 918 debug3("send_pubkey_test"); 919 920 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 921 /* we cannot handle this key */ 922 debug3("send_pubkey_test: cannot handle key"); 923 return 0; 924 } 925 /* register callback for USERAUTH_PK_OK message */ 926 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 927 928 packet_start(SSH2_MSG_USERAUTH_REQUEST); 929 packet_put_cstring(authctxt->server_user); 930 packet_put_cstring(authctxt->service); 931 packet_put_cstring(authctxt->method->name); 932 packet_put_char(have_sig); 933 if (!(datafellows & SSH_BUG_PKAUTH)) 934 packet_put_cstring(key_ssh_name(id->key)); 935 packet_put_string(blob, bloblen); 936 xfree(blob); 937 packet_send(); 938 return 1; 939} 940 941static Key * 942load_identity_file(char *filename) 943{ 944 Key *private; 945 char prompt[300], *passphrase; 946 int quit, i; 947 struct stat st; 948 949 if (stat(filename, &st) < 0) { 950 debug3("no such identity: %s", filename); 951 return NULL; 952 } 953 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 954 if (private == NULL) { 955 if (options.batch_mode) 956 return NULL; 957 snprintf(prompt, sizeof prompt, 958 "Enter passphrase for key '%.100s': ", filename); 959 for (i = 0; i < options.number_of_password_prompts; i++) { 960 passphrase = read_passphrase(prompt, 0); 961 if (strcmp(passphrase, "") != 0) { 962 private = key_load_private_type(KEY_UNSPEC, filename, 963 passphrase, NULL); 964 quit = 0; 965 } else { 966 debug2("no passphrase given, try next key"); 967 quit = 1; 968 } 969 memset(passphrase, 0, strlen(passphrase)); 970 xfree(passphrase); 971 if (private != NULL || quit) 972 break; 973 debug2("bad passphrase given, try again..."); 974 } 975 } 976 return private; 977} 978 979/* 980 * try keys in the following order: 981 * 1. agent keys that are found in the config file 982 * 2. other agent keys 983 * 3. keys that are only listed in the config file 984 */ 985static void 986pubkey_prepare(Authctxt *authctxt) 987{ 988 Identity *id; 989 Idlist agent, files, *preferred; 990 Key *key; 991 AuthenticationConnection *ac; 992 char *comment; 993 int i, found; 994 995 TAILQ_INIT(&agent); /* keys from the agent */ 996 TAILQ_INIT(&files); /* keys from the config file */ 997 preferred = &authctxt->keys; 998 TAILQ_INIT(preferred); /* preferred order of keys */ 999 1000 /* list of keys stored in the filesystem */ 1001 for (i = 0; i < options.num_identity_files; i++) { 1002 key = options.identity_keys[i]; 1003 if (key && key->type == KEY_RSA1) 1004 continue; 1005 options.identity_keys[i] = NULL; 1006 id = xmalloc(sizeof(*id)); 1007 memset(id, 0, sizeof(*id)); 1008 id->key = key; 1009 id->filename = xstrdup(options.identity_files[i]); 1010 TAILQ_INSERT_TAIL(&files, id, next); 1011 } 1012 /* list of keys supported by the agent */ 1013 if ((ac = ssh_get_authentication_connection())) { 1014 for (key = ssh_get_first_identity(ac, &comment, 2); 1015 key != NULL; 1016 key = ssh_get_next_identity(ac, &comment, 2)) { 1017 found = 0; 1018 TAILQ_FOREACH(id, &files, next) { 1019 /* agent keys from the config file are preferred */ 1020 if (key_equal(key, id->key)) { 1021 key_free(key); 1022 xfree(comment); 1023 TAILQ_REMOVE(&files, id, next); 1024 TAILQ_INSERT_TAIL(preferred, id, next); 1025 id->ac = ac; 1026 found = 1; 1027 break; 1028 } 1029 } 1030 if (!found) { 1031 id = xmalloc(sizeof(*id)); 1032 memset(id, 0, sizeof(*id)); 1033 id->key = key; 1034 id->filename = comment; 1035 id->ac = ac; 1036 TAILQ_INSERT_TAIL(&agent, id, next); 1037 } 1038 } 1039 /* append remaining agent keys */ 1040 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1041 TAILQ_REMOVE(&agent, id, next); 1042 TAILQ_INSERT_TAIL(preferred, id, next); 1043 } 1044 authctxt->agent = ac; 1045 } 1046 /* append remaining keys from the config file */ 1047 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1048 TAILQ_REMOVE(&files, id, next); 1049 TAILQ_INSERT_TAIL(preferred, id, next); 1050 } 1051 TAILQ_FOREACH(id, preferred, next) { 1052 debug2("key: %s (%p)", id->filename, id->key); 1053 } 1054} 1055 1056static void 1057pubkey_cleanup(Authctxt *authctxt) 1058{ 1059 Identity *id; 1060 1061 if (authctxt->agent != NULL) 1062 ssh_close_authentication_connection(authctxt->agent); 1063 for (id = TAILQ_FIRST(&authctxt->keys); id; 1064 id = TAILQ_FIRST(&authctxt->keys)) { 1065 TAILQ_REMOVE(&authctxt->keys, id, next); 1066 if (id->key) 1067 key_free(id->key); 1068 if (id->filename) 1069 xfree(id->filename); 1070 xfree(id); 1071 } 1072} 1073 1074int 1075userauth_pubkey(Authctxt *authctxt) 1076{ 1077 Identity *id; 1078 int sent = 0; 1079 1080 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1081 if (id->tried++) 1082 return (0); 1083 TAILQ_REMOVE(&authctxt->keys, id, next); 1084 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1085 /* 1086 * send a test message if we have the public key. for 1087 * encrypted keys we cannot do this and have to load the 1088 * private key instead 1089 */ 1090 if (id->key && id->key->type != KEY_RSA1) { 1091 debug("Offering public key: %s", id->filename); 1092 sent = send_pubkey_test(authctxt, id); 1093 } else if (id->key == NULL) { 1094 debug("Trying private key: %s", id->filename); 1095 id->key = load_identity_file(id->filename); 1096 if (id->key != NULL) { 1097 id->isprivate = 1; 1098 sent = sign_and_send_pubkey(authctxt, id); 1099 key_free(id->key); 1100 id->key = NULL; 1101 } 1102 } 1103 if (sent) 1104 return (sent); 1105 } 1106 return (0); 1107} 1108 1109/* 1110 * Send userauth request message specifying keyboard-interactive method. 1111 */ 1112int 1113userauth_kbdint(Authctxt *authctxt) 1114{ 1115 static int attempt = 0; 1116 1117 if (attempt++ >= options.number_of_password_prompts) 1118 return 0; 1119 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1120 if (attempt > 1 && !authctxt->info_req_seen) { 1121 debug3("userauth_kbdint: disable: no info_req_seen"); 1122 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1123 return 0; 1124 } 1125 1126 debug2("userauth_kbdint"); 1127 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1128 packet_put_cstring(authctxt->server_user); 1129 packet_put_cstring(authctxt->service); 1130 packet_put_cstring(authctxt->method->name); 1131 packet_put_cstring(""); /* lang */ 1132 packet_put_cstring(options.kbd_interactive_devices ? 1133 options.kbd_interactive_devices : ""); 1134 packet_send(); 1135 1136 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1137 return 1; 1138} 1139 1140/* 1141 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1142 */ 1143void 1144input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1145{ 1146 Authctxt *authctxt = ctxt; 1147 char *name, *inst, *lang, *prompt, *response; 1148 u_int num_prompts, i; 1149 int echo = 0; 1150 1151 debug2("input_userauth_info_req"); 1152 1153 if (authctxt == NULL) 1154 fatal("input_userauth_info_req: no authentication context"); 1155 1156 authctxt->info_req_seen = 1; 1157 1158 name = packet_get_string(NULL); 1159 inst = packet_get_string(NULL); 1160 lang = packet_get_string(NULL); 1161 if (strlen(name) > 0) 1162 logit("%s", name); 1163 if (strlen(inst) > 0) 1164 logit("%s", inst); 1165 xfree(name); 1166 xfree(inst); 1167 xfree(lang); 1168 1169 num_prompts = packet_get_int(); 1170 /* 1171 * Begin to build info response packet based on prompts requested. 1172 * We commit to providing the correct number of responses, so if 1173 * further on we run into a problem that prevents this, we have to 1174 * be sure and clean this up and send a correct error response. 1175 */ 1176 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1177 packet_put_int(num_prompts); 1178 1179 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1180 for (i = 0; i < num_prompts; i++) { 1181 prompt = packet_get_string(NULL); 1182 echo = packet_get_char(); 1183 1184 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1185 1186 packet_put_cstring(response); 1187 memset(response, 0, strlen(response)); 1188 xfree(response); 1189 xfree(prompt); 1190 } 1191 packet_check_eom(); /* done with parsing incoming message. */ 1192 1193 packet_add_padding(64); 1194 packet_send(); 1195} 1196 1197static int 1198ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1199 u_char *data, u_int datalen) 1200{ 1201 Buffer b; 1202 struct stat st; 1203 pid_t pid; 1204 int to[2], from[2], status, version = 2; 1205 1206 debug2("ssh_keysign called"); 1207 1208 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1209 error("ssh_keysign: no installed: %s", strerror(errno)); 1210 return -1; 1211 } 1212 if (fflush(stdout) != 0) 1213 error("ssh_keysign: fflush: %s", strerror(errno)); 1214 if (pipe(to) < 0) { 1215 error("ssh_keysign: pipe: %s", strerror(errno)); 1216 return -1; 1217 } 1218 if (pipe(from) < 0) { 1219 error("ssh_keysign: pipe: %s", strerror(errno)); 1220 return -1; 1221 } 1222 if ((pid = fork()) < 0) { 1223 error("ssh_keysign: fork: %s", strerror(errno)); 1224 return -1; 1225 } 1226 if (pid == 0) { 1227 seteuid(getuid()); 1228 setuid(getuid()); 1229 close(from[0]); 1230 if (dup2(from[1], STDOUT_FILENO) < 0) 1231 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1232 close(to[1]); 1233 if (dup2(to[0], STDIN_FILENO) < 0) 1234 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1235 close(from[1]); 1236 close(to[0]); 1237 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1238 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1239 strerror(errno)); 1240 } 1241 close(from[1]); 1242 close(to[0]); 1243 1244 buffer_init(&b); 1245 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1246 buffer_put_string(&b, data, datalen); 1247 ssh_msg_send(to[1], version, &b); 1248 1249 if (ssh_msg_recv(from[0], &b) < 0) { 1250 error("ssh_keysign: no reply"); 1251 buffer_clear(&b); 1252 return -1; 1253 } 1254 close(from[0]); 1255 close(to[1]); 1256 1257 while (waitpid(pid, &status, 0) < 0) 1258 if (errno != EINTR) 1259 break; 1260 1261 if (buffer_get_char(&b) != version) { 1262 error("ssh_keysign: bad version"); 1263 buffer_clear(&b); 1264 return -1; 1265 } 1266 *sigp = buffer_get_string(&b, lenp); 1267 buffer_clear(&b); 1268 1269 return 0; 1270} 1271 1272int 1273userauth_hostbased(Authctxt *authctxt) 1274{ 1275 Key *private = NULL; 1276 Sensitive *sensitive = authctxt->sensitive; 1277 Buffer b; 1278 u_char *signature, *blob; 1279 char *chost, *pkalg, *p; 1280 const char *service; 1281 u_int blen, slen; 1282 int ok, i, len, found = 0; 1283 1284 /* check for a useful key */ 1285 for (i = 0; i < sensitive->nkeys; i++) { 1286 private = sensitive->keys[i]; 1287 if (private && private->type != KEY_RSA1) { 1288 found = 1; 1289 /* we take and free the key */ 1290 sensitive->keys[i] = NULL; 1291 break; 1292 } 1293 } 1294 if (!found) { 1295 debug("No more client hostkeys for hostbased authentication."); 1296 return 0; 1297 } 1298 if (key_to_blob(private, &blob, &blen) == 0) { 1299 key_free(private); 1300 return 0; 1301 } 1302 /* figure out a name for the client host */ 1303 p = get_local_name(packet_get_connection_in()); 1304 if (p == NULL) { 1305 error("userauth_hostbased: cannot get local ipaddr/name"); 1306 key_free(private); 1307 return 0; 1308 } 1309 len = strlen(p) + 2; 1310 chost = xmalloc(len); 1311 strlcpy(chost, p, len); 1312 strlcat(chost, ".", len); 1313 debug2("userauth_hostbased: chost %s", chost); 1314 xfree(p); 1315 1316 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1317 authctxt->service; 1318 pkalg = xstrdup(key_ssh_name(private)); 1319 buffer_init(&b); 1320 /* construct data */ 1321 buffer_put_string(&b, session_id2, session_id2_len); 1322 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1323 buffer_put_cstring(&b, authctxt->server_user); 1324 buffer_put_cstring(&b, service); 1325 buffer_put_cstring(&b, authctxt->method->name); 1326 buffer_put_cstring(&b, pkalg); 1327 buffer_put_string(&b, blob, blen); 1328 buffer_put_cstring(&b, chost); 1329 buffer_put_cstring(&b, authctxt->local_user); 1330#ifdef DEBUG_PK 1331 buffer_dump(&b); 1332#endif 1333 if (sensitive->external_keysign) 1334 ok = ssh_keysign(private, &signature, &slen, 1335 buffer_ptr(&b), buffer_len(&b)); 1336 else 1337 ok = key_sign(private, &signature, &slen, 1338 buffer_ptr(&b), buffer_len(&b)); 1339 key_free(private); 1340 buffer_free(&b); 1341 if (ok != 0) { 1342 error("key_sign failed"); 1343 xfree(chost); 1344 xfree(pkalg); 1345 return 0; 1346 } 1347 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1348 packet_put_cstring(authctxt->server_user); 1349 packet_put_cstring(authctxt->service); 1350 packet_put_cstring(authctxt->method->name); 1351 packet_put_cstring(pkalg); 1352 packet_put_string(blob, blen); 1353 packet_put_cstring(chost); 1354 packet_put_cstring(authctxt->local_user); 1355 packet_put_string(signature, slen); 1356 memset(signature, 's', slen); 1357 xfree(signature); 1358 xfree(chost); 1359 xfree(pkalg); 1360 1361 packet_send(); 1362 return 1; 1363} 1364 1365/* find auth method */ 1366 1367/* 1368 * given auth method name, if configurable options permit this method fill 1369 * in auth_ident field and return true, otherwise return false. 1370 */ 1371static int 1372authmethod_is_enabled(Authmethod *method) 1373{ 1374 if (method == NULL) 1375 return 0; 1376 /* return false if options indicate this method is disabled */ 1377 if (method->enabled == NULL || *method->enabled == 0) 1378 return 0; 1379 /* return false if batch mode is enabled but method needs interactive mode */ 1380 if (method->batch_flag != NULL && *method->batch_flag != 0) 1381 return 0; 1382 return 1; 1383} 1384 1385static Authmethod * 1386authmethod_lookup(const char *name) 1387{ 1388 Authmethod *method = NULL; 1389 if (name != NULL) 1390 for (method = authmethods; method->name != NULL; method++) 1391 if (strcmp(name, method->name) == 0) 1392 return method; 1393 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1394 return NULL; 1395} 1396 1397/* XXX internal state */ 1398static Authmethod *current = NULL; 1399static char *supported = NULL; 1400static char *preferred = NULL; 1401 1402/* 1403 * Given the authentication method list sent by the server, return the 1404 * next method we should try. If the server initially sends a nil list, 1405 * use a built-in default list. 1406 */ 1407static Authmethod * 1408authmethod_get(char *authlist) 1409{ 1410 char *name = NULL; 1411 u_int next; 1412 1413 /* Use a suitable default if we're passed a nil list. */ 1414 if (authlist == NULL || strlen(authlist) == 0) 1415 authlist = options.preferred_authentications; 1416 1417 if (supported == NULL || strcmp(authlist, supported) != 0) { 1418 debug3("start over, passed a different list %s", authlist); 1419 if (supported != NULL) 1420 xfree(supported); 1421 supported = xstrdup(authlist); 1422 preferred = options.preferred_authentications; 1423 debug3("preferred %s", preferred); 1424 current = NULL; 1425 } else if (current != NULL && authmethod_is_enabled(current)) 1426 return current; 1427 1428 for (;;) { 1429 if ((name = match_list(preferred, supported, &next)) == NULL) { 1430 debug("No more authentication methods to try."); 1431 current = NULL; 1432 return NULL; 1433 } 1434 preferred += next; 1435 debug3("authmethod_lookup %s", name); 1436 debug3("remaining preferred: %s", preferred); 1437 if ((current = authmethod_lookup(name)) != NULL && 1438 authmethod_is_enabled(current)) { 1439 debug3("authmethod_is_enabled %s", name); 1440 debug("Next authentication method: %s", name); 1441 return current; 1442 } 1443 } 1444} 1445 1446static char * 1447authmethods_get(void) 1448{ 1449 Authmethod *method = NULL; 1450 Buffer b; 1451 char *list; 1452 1453 buffer_init(&b); 1454 for (method = authmethods; method->name != NULL; method++) { 1455 if (authmethod_is_enabled(method)) { 1456 if (buffer_len(&b) > 0) 1457 buffer_append(&b, ",", 1); 1458 buffer_append(&b, method->name, strlen(method->name)); 1459 } 1460 } 1461 buffer_append(&b, "\0", 1); 1462 list = xstrdup(buffer_ptr(&b)); 1463 buffer_free(&b); 1464 return list; 1465} 1466