sshconnect2.c revision 157019
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 1.143 2005/10/14 02:17:59 stevesk 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@openssh.com,zlib,none"; 105 } else { 106 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 107 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,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 u_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) 513 return 0; 514 515 authctxt->methoddata=(void *)gssctxt; 516 517 packet_start(SSH2_MSG_USERAUTH_REQUEST); 518 packet_put_cstring(authctxt->server_user); 519 packet_put_cstring(authctxt->service); 520 packet_put_cstring(authctxt->method->name); 521 522 packet_put_int(1); 523 524 packet_put_int((gss_supported->elements[mech].length) + 2); 525 packet_put_char(SSH_GSS_OIDTYPE); 526 packet_put_char(gss_supported->elements[mech].length); 527 packet_put_raw(gss_supported->elements[mech].elements, 528 gss_supported->elements[mech].length); 529 530 packet_send(); 531 532 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 533 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 534 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 535 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 536 537 mech++; /* Move along to next candidate */ 538 539 return 1; 540} 541 542static OM_uint32 543process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 544{ 545 Authctxt *authctxt = ctxt; 546 Gssctxt *gssctxt = authctxt->methoddata; 547 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 548 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 549 gss_buffer_desc gssbuf; 550 OM_uint32 status, ms, flags; 551 Buffer b; 552 553 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 554 recv_tok, &send_tok, &flags); 555 556 if (send_tok.length > 0) { 557 if (GSS_ERROR(status)) 558 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 559 else 560 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 561 562 packet_put_string(send_tok.value, send_tok.length); 563 packet_send(); 564 gss_release_buffer(&ms, &send_tok); 565 } 566 567 if (status == GSS_S_COMPLETE) { 568 /* send either complete or MIC, depending on mechanism */ 569 if (!(flags & GSS_C_INTEG_FLAG)) { 570 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 571 packet_send(); 572 } else { 573 ssh_gssapi_buildmic(&b, authctxt->server_user, 574 authctxt->service, "gssapi-with-mic"); 575 576 gssbuf.value = buffer_ptr(&b); 577 gssbuf.length = buffer_len(&b); 578 579 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 580 581 if (!GSS_ERROR(status)) { 582 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 583 packet_put_string(mic.value, mic.length); 584 585 packet_send(); 586 } 587 588 buffer_free(&b); 589 gss_release_buffer(&ms, &mic); 590 } 591 } 592 593 return status; 594} 595 596void 597input_gssapi_response(int type, u_int32_t plen, void *ctxt) 598{ 599 Authctxt *authctxt = ctxt; 600 Gssctxt *gssctxt; 601 int oidlen; 602 char *oidv; 603 604 if (authctxt == NULL) 605 fatal("input_gssapi_response: no authentication context"); 606 gssctxt = authctxt->methoddata; 607 608 /* Setup our OID */ 609 oidv = packet_get_string(&oidlen); 610 611 if (oidlen <= 2 || 612 oidv[0] != SSH_GSS_OIDTYPE || 613 oidv[1] != oidlen - 2) { 614 xfree(oidv); 615 debug("Badly encoded mechanism OID received"); 616 userauth(authctxt, NULL); 617 return; 618 } 619 620 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 621 fatal("Server returned different OID than expected"); 622 623 packet_check_eom(); 624 625 xfree(oidv); 626 627 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 628 /* Start again with next method on list */ 629 debug("Trying to start again"); 630 userauth(authctxt, NULL); 631 return; 632 } 633} 634 635void 636input_gssapi_token(int type, u_int32_t plen, void *ctxt) 637{ 638 Authctxt *authctxt = ctxt; 639 gss_buffer_desc recv_tok; 640 OM_uint32 status; 641 u_int slen; 642 643 if (authctxt == NULL) 644 fatal("input_gssapi_response: no authentication context"); 645 646 recv_tok.value = packet_get_string(&slen); 647 recv_tok.length = slen; /* safe typecast */ 648 649 packet_check_eom(); 650 651 status = process_gssapi_token(ctxt, &recv_tok); 652 653 xfree(recv_tok.value); 654 655 if (GSS_ERROR(status)) { 656 /* Start again with the next method in the list */ 657 userauth(authctxt, NULL); 658 return; 659 } 660} 661 662void 663input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 664{ 665 Authctxt *authctxt = ctxt; 666 Gssctxt *gssctxt; 667 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 668 gss_buffer_desc recv_tok; 669 OM_uint32 status, ms; 670 u_int len; 671 672 if (authctxt == NULL) 673 fatal("input_gssapi_response: no authentication context"); 674 gssctxt = authctxt->methoddata; 675 676 recv_tok.value = packet_get_string(&len); 677 recv_tok.length = len; 678 679 packet_check_eom(); 680 681 /* Stick it into GSSAPI and see what it says */ 682 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 683 &recv_tok, &send_tok, NULL); 684 685 xfree(recv_tok.value); 686 gss_release_buffer(&ms, &send_tok); 687 688 /* Server will be returning a failed packet after this one */ 689} 690 691void 692input_gssapi_error(int type, u_int32_t plen, void *ctxt) 693{ 694 OM_uint32 maj, min; 695 char *msg; 696 char *lang; 697 698 maj=packet_get_int(); 699 min=packet_get_int(); 700 msg=packet_get_string(NULL); 701 lang=packet_get_string(NULL); 702 703 packet_check_eom(); 704 705 debug("Server GSSAPI Error:\n%s", msg); 706 xfree(msg); 707 xfree(lang); 708} 709#endif /* GSSAPI */ 710 711int 712userauth_none(Authctxt *authctxt) 713{ 714 /* initial userauth request */ 715 packet_start(SSH2_MSG_USERAUTH_REQUEST); 716 packet_put_cstring(authctxt->server_user); 717 packet_put_cstring(authctxt->service); 718 packet_put_cstring(authctxt->method->name); 719 packet_send(); 720 return 1; 721} 722 723int 724userauth_passwd(Authctxt *authctxt) 725{ 726 static int attempt = 0; 727 char prompt[150]; 728 char *password; 729 730 if (attempt++ >= options.number_of_password_prompts) 731 return 0; 732 733 if (attempt != 1) 734 error("Permission denied, please try again."); 735 736 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 737 authctxt->server_user, authctxt->host); 738 password = read_passphrase(prompt, 0); 739 packet_start(SSH2_MSG_USERAUTH_REQUEST); 740 packet_put_cstring(authctxt->server_user); 741 packet_put_cstring(authctxt->service); 742 packet_put_cstring(authctxt->method->name); 743 packet_put_char(0); 744 packet_put_cstring(password); 745 memset(password, 0, strlen(password)); 746 xfree(password); 747 packet_add_padding(64); 748 packet_send(); 749 750 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 751 &input_userauth_passwd_changereq); 752 753 return 1; 754} 755/* 756 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 757 */ 758void 759input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 760{ 761 Authctxt *authctxt = ctxt; 762 char *info, *lang, *password = NULL, *retype = NULL; 763 char prompt[150]; 764 765 debug2("input_userauth_passwd_changereq"); 766 767 if (authctxt == NULL) 768 fatal("input_userauth_passwd_changereq: " 769 "no authentication context"); 770 771 info = packet_get_string(NULL); 772 lang = packet_get_string(NULL); 773 if (strlen(info) > 0) 774 logit("%s", info); 775 xfree(info); 776 xfree(lang); 777 packet_start(SSH2_MSG_USERAUTH_REQUEST); 778 packet_put_cstring(authctxt->server_user); 779 packet_put_cstring(authctxt->service); 780 packet_put_cstring(authctxt->method->name); 781 packet_put_char(1); /* additional info */ 782 snprintf(prompt, sizeof(prompt), 783 "Enter %.30s@%.128s's old password: ", 784 authctxt->server_user, authctxt->host); 785 password = read_passphrase(prompt, 0); 786 packet_put_cstring(password); 787 memset(password, 0, strlen(password)); 788 xfree(password); 789 password = NULL; 790 while (password == NULL) { 791 snprintf(prompt, sizeof(prompt), 792 "Enter %.30s@%.128s's new password: ", 793 authctxt->server_user, authctxt->host); 794 password = read_passphrase(prompt, RP_ALLOW_EOF); 795 if (password == NULL) { 796 /* bail out */ 797 return; 798 } 799 snprintf(prompt, sizeof(prompt), 800 "Retype %.30s@%.128s's new password: ", 801 authctxt->server_user, authctxt->host); 802 retype = read_passphrase(prompt, 0); 803 if (strcmp(password, retype) != 0) { 804 memset(password, 0, strlen(password)); 805 xfree(password); 806 logit("Mismatch; try again, EOF to quit."); 807 password = NULL; 808 } 809 memset(retype, 0, strlen(retype)); 810 xfree(retype); 811 } 812 packet_put_cstring(password); 813 memset(password, 0, strlen(password)); 814 xfree(password); 815 packet_add_padding(64); 816 packet_send(); 817 818 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 819 &input_userauth_passwd_changereq); 820} 821 822static int 823identity_sign(Identity *id, u_char **sigp, u_int *lenp, 824 u_char *data, u_int datalen) 825{ 826 Key *prv; 827 int ret; 828 829 /* the agent supports this key */ 830 if (id->ac) 831 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 832 data, datalen)); 833 /* 834 * we have already loaded the private key or 835 * the private key is stored in external hardware 836 */ 837 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 838 return (key_sign(id->key, sigp, lenp, data, datalen)); 839 /* load the private key from the file */ 840 if ((prv = load_identity_file(id->filename)) == NULL) 841 return (-1); 842 ret = key_sign(prv, sigp, lenp, data, datalen); 843 key_free(prv); 844 return (ret); 845} 846 847static int 848sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 849{ 850 Buffer b; 851 u_char *blob, *signature; 852 u_int bloblen, slen; 853 u_int skip = 0; 854 int ret = -1; 855 int have_sig = 1; 856 857 debug3("sign_and_send_pubkey"); 858 859 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 860 /* we cannot handle this key */ 861 debug3("sign_and_send_pubkey: cannot handle key"); 862 return 0; 863 } 864 /* data to be signed */ 865 buffer_init(&b); 866 if (datafellows & SSH_OLD_SESSIONID) { 867 buffer_append(&b, session_id2, session_id2_len); 868 skip = session_id2_len; 869 } else { 870 buffer_put_string(&b, session_id2, session_id2_len); 871 skip = buffer_len(&b); 872 } 873 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 874 buffer_put_cstring(&b, authctxt->server_user); 875 buffer_put_cstring(&b, 876 datafellows & SSH_BUG_PKSERVICE ? 877 "ssh-userauth" : 878 authctxt->service); 879 if (datafellows & SSH_BUG_PKAUTH) { 880 buffer_put_char(&b, have_sig); 881 } else { 882 buffer_put_cstring(&b, authctxt->method->name); 883 buffer_put_char(&b, have_sig); 884 buffer_put_cstring(&b, key_ssh_name(id->key)); 885 } 886 buffer_put_string(&b, blob, bloblen); 887 888 /* generate signature */ 889 ret = identity_sign(id, &signature, &slen, 890 buffer_ptr(&b), buffer_len(&b)); 891 if (ret == -1) { 892 xfree(blob); 893 buffer_free(&b); 894 return 0; 895 } 896#ifdef DEBUG_PK 897 buffer_dump(&b); 898#endif 899 if (datafellows & SSH_BUG_PKSERVICE) { 900 buffer_clear(&b); 901 buffer_append(&b, session_id2, session_id2_len); 902 skip = session_id2_len; 903 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 904 buffer_put_cstring(&b, authctxt->server_user); 905 buffer_put_cstring(&b, authctxt->service); 906 buffer_put_cstring(&b, authctxt->method->name); 907 buffer_put_char(&b, have_sig); 908 if (!(datafellows & SSH_BUG_PKAUTH)) 909 buffer_put_cstring(&b, key_ssh_name(id->key)); 910 buffer_put_string(&b, blob, bloblen); 911 } 912 xfree(blob); 913 914 /* append signature */ 915 buffer_put_string(&b, signature, slen); 916 xfree(signature); 917 918 /* skip session id and packet type */ 919 if (buffer_len(&b) < skip + 1) 920 fatal("userauth_pubkey: internal error"); 921 buffer_consume(&b, skip + 1); 922 923 /* put remaining data from buffer into packet */ 924 packet_start(SSH2_MSG_USERAUTH_REQUEST); 925 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 926 buffer_free(&b); 927 packet_send(); 928 929 return 1; 930} 931 932static int 933send_pubkey_test(Authctxt *authctxt, Identity *id) 934{ 935 u_char *blob; 936 u_int bloblen, have_sig = 0; 937 938 debug3("send_pubkey_test"); 939 940 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 941 /* we cannot handle this key */ 942 debug3("send_pubkey_test: cannot handle key"); 943 return 0; 944 } 945 /* register callback for USERAUTH_PK_OK message */ 946 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 947 948 packet_start(SSH2_MSG_USERAUTH_REQUEST); 949 packet_put_cstring(authctxt->server_user); 950 packet_put_cstring(authctxt->service); 951 packet_put_cstring(authctxt->method->name); 952 packet_put_char(have_sig); 953 if (!(datafellows & SSH_BUG_PKAUTH)) 954 packet_put_cstring(key_ssh_name(id->key)); 955 packet_put_string(blob, bloblen); 956 xfree(blob); 957 packet_send(); 958 return 1; 959} 960 961static Key * 962load_identity_file(char *filename) 963{ 964 Key *private; 965 char prompt[300], *passphrase; 966 int quit, i; 967 struct stat st; 968 969 if (stat(filename, &st) < 0) { 970 debug3("no such identity: %s", filename); 971 return NULL; 972 } 973 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 974 if (private == NULL) { 975 if (options.batch_mode) 976 return NULL; 977 snprintf(prompt, sizeof prompt, 978 "Enter passphrase for key '%.100s': ", filename); 979 for (i = 0; i < options.number_of_password_prompts; i++) { 980 passphrase = read_passphrase(prompt, 0); 981 if (strcmp(passphrase, "") != 0) { 982 private = key_load_private_type(KEY_UNSPEC, filename, 983 passphrase, NULL); 984 quit = 0; 985 } else { 986 debug2("no passphrase given, try next key"); 987 quit = 1; 988 } 989 memset(passphrase, 0, strlen(passphrase)); 990 xfree(passphrase); 991 if (private != NULL || quit) 992 break; 993 debug2("bad passphrase given, try again..."); 994 } 995 } 996 return private; 997} 998 999/* 1000 * try keys in the following order: 1001 * 1. agent keys that are found in the config file 1002 * 2. other agent keys 1003 * 3. keys that are only listed in the config file 1004 */ 1005static void 1006pubkey_prepare(Authctxt *authctxt) 1007{ 1008 Identity *id; 1009 Idlist agent, files, *preferred; 1010 Key *key; 1011 AuthenticationConnection *ac; 1012 char *comment; 1013 int i, found; 1014 1015 TAILQ_INIT(&agent); /* keys from the agent */ 1016 TAILQ_INIT(&files); /* keys from the config file */ 1017 preferred = &authctxt->keys; 1018 TAILQ_INIT(preferred); /* preferred order of keys */ 1019 1020 /* list of keys stored in the filesystem */ 1021 for (i = 0; i < options.num_identity_files; i++) { 1022 key = options.identity_keys[i]; 1023 if (key && key->type == KEY_RSA1) 1024 continue; 1025 options.identity_keys[i] = NULL; 1026 id = xmalloc(sizeof(*id)); 1027 memset(id, 0, sizeof(*id)); 1028 id->key = key; 1029 id->filename = xstrdup(options.identity_files[i]); 1030 TAILQ_INSERT_TAIL(&files, id, next); 1031 } 1032 /* list of keys supported by the agent */ 1033 if ((ac = ssh_get_authentication_connection())) { 1034 for (key = ssh_get_first_identity(ac, &comment, 2); 1035 key != NULL; 1036 key = ssh_get_next_identity(ac, &comment, 2)) { 1037 found = 0; 1038 TAILQ_FOREACH(id, &files, next) { 1039 /* agent keys from the config file are preferred */ 1040 if (key_equal(key, id->key)) { 1041 key_free(key); 1042 xfree(comment); 1043 TAILQ_REMOVE(&files, id, next); 1044 TAILQ_INSERT_TAIL(preferred, id, next); 1045 id->ac = ac; 1046 found = 1; 1047 break; 1048 } 1049 } 1050 if (!found && !options.identities_only) { 1051 id = xmalloc(sizeof(*id)); 1052 memset(id, 0, sizeof(*id)); 1053 id->key = key; 1054 id->filename = comment; 1055 id->ac = ac; 1056 TAILQ_INSERT_TAIL(&agent, id, next); 1057 } 1058 } 1059 /* append remaining agent keys */ 1060 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1061 TAILQ_REMOVE(&agent, id, next); 1062 TAILQ_INSERT_TAIL(preferred, id, next); 1063 } 1064 authctxt->agent = ac; 1065 } 1066 /* append remaining keys from the config file */ 1067 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1068 TAILQ_REMOVE(&files, id, next); 1069 TAILQ_INSERT_TAIL(preferred, id, next); 1070 } 1071 TAILQ_FOREACH(id, preferred, next) { 1072 debug2("key: %s (%p)", id->filename, id->key); 1073 } 1074} 1075 1076static void 1077pubkey_cleanup(Authctxt *authctxt) 1078{ 1079 Identity *id; 1080 1081 if (authctxt->agent != NULL) 1082 ssh_close_authentication_connection(authctxt->agent); 1083 for (id = TAILQ_FIRST(&authctxt->keys); id; 1084 id = TAILQ_FIRST(&authctxt->keys)) { 1085 TAILQ_REMOVE(&authctxt->keys, id, next); 1086 if (id->key) 1087 key_free(id->key); 1088 if (id->filename) 1089 xfree(id->filename); 1090 xfree(id); 1091 } 1092} 1093 1094int 1095userauth_pubkey(Authctxt *authctxt) 1096{ 1097 Identity *id; 1098 int sent = 0; 1099 1100 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1101 if (id->tried++) 1102 return (0); 1103 /* move key to the end of the queue */ 1104 TAILQ_REMOVE(&authctxt->keys, id, next); 1105 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1106 /* 1107 * send a test message if we have the public key. for 1108 * encrypted keys we cannot do this and have to load the 1109 * private key instead 1110 */ 1111 if (id->key && id->key->type != KEY_RSA1) { 1112 debug("Offering public key: %s", id->filename); 1113 sent = send_pubkey_test(authctxt, id); 1114 } else if (id->key == NULL) { 1115 debug("Trying private key: %s", id->filename); 1116 id->key = load_identity_file(id->filename); 1117 if (id->key != NULL) { 1118 id->isprivate = 1; 1119 sent = sign_and_send_pubkey(authctxt, id); 1120 key_free(id->key); 1121 id->key = NULL; 1122 } 1123 } 1124 if (sent) 1125 return (sent); 1126 } 1127 return (0); 1128} 1129 1130/* 1131 * Send userauth request message specifying keyboard-interactive method. 1132 */ 1133int 1134userauth_kbdint(Authctxt *authctxt) 1135{ 1136 static int attempt = 0; 1137 1138 if (attempt++ >= options.number_of_password_prompts) 1139 return 0; 1140 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1141 if (attempt > 1 && !authctxt->info_req_seen) { 1142 debug3("userauth_kbdint: disable: no info_req_seen"); 1143 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1144 return 0; 1145 } 1146 1147 debug2("userauth_kbdint"); 1148 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1149 packet_put_cstring(authctxt->server_user); 1150 packet_put_cstring(authctxt->service); 1151 packet_put_cstring(authctxt->method->name); 1152 packet_put_cstring(""); /* lang */ 1153 packet_put_cstring(options.kbd_interactive_devices ? 1154 options.kbd_interactive_devices : ""); 1155 packet_send(); 1156 1157 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1158 return 1; 1159} 1160 1161/* 1162 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1163 */ 1164void 1165input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1166{ 1167 Authctxt *authctxt = ctxt; 1168 char *name, *inst, *lang, *prompt, *response; 1169 u_int num_prompts, i; 1170 int echo = 0; 1171 1172 debug2("input_userauth_info_req"); 1173 1174 if (authctxt == NULL) 1175 fatal("input_userauth_info_req: no authentication context"); 1176 1177 authctxt->info_req_seen = 1; 1178 1179 name = packet_get_string(NULL); 1180 inst = packet_get_string(NULL); 1181 lang = packet_get_string(NULL); 1182 if (strlen(name) > 0) 1183 logit("%s", name); 1184 if (strlen(inst) > 0) 1185 logit("%s", inst); 1186 xfree(name); 1187 xfree(inst); 1188 xfree(lang); 1189 1190 num_prompts = packet_get_int(); 1191 /* 1192 * Begin to build info response packet based on prompts requested. 1193 * We commit to providing the correct number of responses, so if 1194 * further on we run into a problem that prevents this, we have to 1195 * be sure and clean this up and send a correct error response. 1196 */ 1197 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1198 packet_put_int(num_prompts); 1199 1200 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1201 for (i = 0; i < num_prompts; i++) { 1202 prompt = packet_get_string(NULL); 1203 echo = packet_get_char(); 1204 1205 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1206 1207 packet_put_cstring(response); 1208 memset(response, 0, strlen(response)); 1209 xfree(response); 1210 xfree(prompt); 1211 } 1212 packet_check_eom(); /* done with parsing incoming message. */ 1213 1214 packet_add_padding(64); 1215 packet_send(); 1216} 1217 1218static int 1219ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1220 u_char *data, u_int datalen) 1221{ 1222 Buffer b; 1223 struct stat st; 1224 pid_t pid; 1225 int to[2], from[2], status, version = 2; 1226 1227 debug2("ssh_keysign called"); 1228 1229 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1230 error("ssh_keysign: no installed: %s", strerror(errno)); 1231 return -1; 1232 } 1233 if (fflush(stdout) != 0) 1234 error("ssh_keysign: fflush: %s", strerror(errno)); 1235 if (pipe(to) < 0) { 1236 error("ssh_keysign: pipe: %s", strerror(errno)); 1237 return -1; 1238 } 1239 if (pipe(from) < 0) { 1240 error("ssh_keysign: pipe: %s", strerror(errno)); 1241 return -1; 1242 } 1243 if ((pid = fork()) < 0) { 1244 error("ssh_keysign: fork: %s", strerror(errno)); 1245 return -1; 1246 } 1247 if (pid == 0) { 1248 seteuid(getuid()); 1249 setuid(getuid()); 1250 close(from[0]); 1251 if (dup2(from[1], STDOUT_FILENO) < 0) 1252 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1253 close(to[1]); 1254 if (dup2(to[0], STDIN_FILENO) < 0) 1255 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1256 close(from[1]); 1257 close(to[0]); 1258 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1259 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1260 strerror(errno)); 1261 } 1262 close(from[1]); 1263 close(to[0]); 1264 1265 buffer_init(&b); 1266 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1267 buffer_put_string(&b, data, datalen); 1268 if (ssh_msg_send(to[1], version, &b) == -1) 1269 fatal("ssh_keysign: couldn't send request"); 1270 1271 if (ssh_msg_recv(from[0], &b) < 0) { 1272 error("ssh_keysign: no reply"); 1273 buffer_free(&b); 1274 return -1; 1275 } 1276 close(from[0]); 1277 close(to[1]); 1278 1279 while (waitpid(pid, &status, 0) < 0) 1280 if (errno != EINTR) 1281 break; 1282 1283 if (buffer_get_char(&b) != version) { 1284 error("ssh_keysign: bad version"); 1285 buffer_free(&b); 1286 return -1; 1287 } 1288 *sigp = buffer_get_string(&b, lenp); 1289 buffer_free(&b); 1290 1291 return 0; 1292} 1293 1294int 1295userauth_hostbased(Authctxt *authctxt) 1296{ 1297 Key *private = NULL; 1298 Sensitive *sensitive = authctxt->sensitive; 1299 Buffer b; 1300 u_char *signature, *blob; 1301 char *chost, *pkalg, *p; 1302 const char *service; 1303 u_int blen, slen; 1304 int ok, i, len, found = 0; 1305 1306 /* check for a useful key */ 1307 for (i = 0; i < sensitive->nkeys; i++) { 1308 private = sensitive->keys[i]; 1309 if (private && private->type != KEY_RSA1) { 1310 found = 1; 1311 /* we take and free the key */ 1312 sensitive->keys[i] = NULL; 1313 break; 1314 } 1315 } 1316 if (!found) { 1317 debug("No more client hostkeys for hostbased authentication."); 1318 return 0; 1319 } 1320 if (key_to_blob(private, &blob, &blen) == 0) { 1321 key_free(private); 1322 return 0; 1323 } 1324 /* figure out a name for the client host */ 1325 p = get_local_name(packet_get_connection_in()); 1326 if (p == NULL) { 1327 error("userauth_hostbased: cannot get local ipaddr/name"); 1328 key_free(private); 1329 return 0; 1330 } 1331 len = strlen(p) + 2; 1332 chost = xmalloc(len); 1333 strlcpy(chost, p, len); 1334 strlcat(chost, ".", len); 1335 debug2("userauth_hostbased: chost %s", chost); 1336 xfree(p); 1337 1338 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1339 authctxt->service; 1340 pkalg = xstrdup(key_ssh_name(private)); 1341 buffer_init(&b); 1342 /* construct data */ 1343 buffer_put_string(&b, session_id2, session_id2_len); 1344 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1345 buffer_put_cstring(&b, authctxt->server_user); 1346 buffer_put_cstring(&b, service); 1347 buffer_put_cstring(&b, authctxt->method->name); 1348 buffer_put_cstring(&b, pkalg); 1349 buffer_put_string(&b, blob, blen); 1350 buffer_put_cstring(&b, chost); 1351 buffer_put_cstring(&b, authctxt->local_user); 1352#ifdef DEBUG_PK 1353 buffer_dump(&b); 1354#endif 1355 if (sensitive->external_keysign) 1356 ok = ssh_keysign(private, &signature, &slen, 1357 buffer_ptr(&b), buffer_len(&b)); 1358 else 1359 ok = key_sign(private, &signature, &slen, 1360 buffer_ptr(&b), buffer_len(&b)); 1361 key_free(private); 1362 buffer_free(&b); 1363 if (ok != 0) { 1364 error("key_sign failed"); 1365 xfree(chost); 1366 xfree(pkalg); 1367 return 0; 1368 } 1369 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1370 packet_put_cstring(authctxt->server_user); 1371 packet_put_cstring(authctxt->service); 1372 packet_put_cstring(authctxt->method->name); 1373 packet_put_cstring(pkalg); 1374 packet_put_string(blob, blen); 1375 packet_put_cstring(chost); 1376 packet_put_cstring(authctxt->local_user); 1377 packet_put_string(signature, slen); 1378 memset(signature, 's', slen); 1379 xfree(signature); 1380 xfree(chost); 1381 xfree(pkalg); 1382 1383 packet_send(); 1384 return 1; 1385} 1386 1387/* find auth method */ 1388 1389/* 1390 * given auth method name, if configurable options permit this method fill 1391 * in auth_ident field and return true, otherwise return false. 1392 */ 1393static int 1394authmethod_is_enabled(Authmethod *method) 1395{ 1396 if (method == NULL) 1397 return 0; 1398 /* return false if options indicate this method is disabled */ 1399 if (method->enabled == NULL || *method->enabled == 0) 1400 return 0; 1401 /* return false if batch mode is enabled but method needs interactive mode */ 1402 if (method->batch_flag != NULL && *method->batch_flag != 0) 1403 return 0; 1404 return 1; 1405} 1406 1407static Authmethod * 1408authmethod_lookup(const char *name) 1409{ 1410 Authmethod *method = NULL; 1411 if (name != NULL) 1412 for (method = authmethods; method->name != NULL; method++) 1413 if (strcmp(name, method->name) == 0) 1414 return method; 1415 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1416 return NULL; 1417} 1418 1419/* XXX internal state */ 1420static Authmethod *current = NULL; 1421static char *supported = NULL; 1422static char *preferred = NULL; 1423 1424/* 1425 * Given the authentication method list sent by the server, return the 1426 * next method we should try. If the server initially sends a nil list, 1427 * use a built-in default list. 1428 */ 1429static Authmethod * 1430authmethod_get(char *authlist) 1431{ 1432 char *name = NULL; 1433 u_int next; 1434 1435 /* Use a suitable default if we're passed a nil list. */ 1436 if (authlist == NULL || strlen(authlist) == 0) 1437 authlist = options.preferred_authentications; 1438 1439 if (supported == NULL || strcmp(authlist, supported) != 0) { 1440 debug3("start over, passed a different list %s", authlist); 1441 if (supported != NULL) 1442 xfree(supported); 1443 supported = xstrdup(authlist); 1444 preferred = options.preferred_authentications; 1445 debug3("preferred %s", preferred); 1446 current = NULL; 1447 } else if (current != NULL && authmethod_is_enabled(current)) 1448 return current; 1449 1450 for (;;) { 1451 if ((name = match_list(preferred, supported, &next)) == NULL) { 1452 debug("No more authentication methods to try."); 1453 current = NULL; 1454 return NULL; 1455 } 1456 preferred += next; 1457 debug3("authmethod_lookup %s", name); 1458 debug3("remaining preferred: %s", preferred); 1459 if ((current = authmethod_lookup(name)) != NULL && 1460 authmethod_is_enabled(current)) { 1461 debug3("authmethod_is_enabled %s", name); 1462 debug("Next authentication method: %s", name); 1463 return current; 1464 } 1465 } 1466} 1467 1468static char * 1469authmethods_get(void) 1470{ 1471 Authmethod *method = NULL; 1472 Buffer b; 1473 char *list; 1474 1475 buffer_init(&b); 1476 for (method = authmethods; method->name != NULL; method++) { 1477 if (authmethod_is_enabled(method)) { 1478 if (buffer_len(&b) > 0) 1479 buffer_append(&b, ",", 1); 1480 buffer_append(&b, method->name, strlen(method->name)); 1481 } 1482 } 1483 buffer_append(&b, "\0", 1); 1484 list = xstrdup(buffer_ptr(&b)); 1485 buffer_free(&b); 1486 return list; 1487} 1488