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" 26 RCSID("$OpenBSD: sshconnect2.c,v 1.135 2004/03/05 10:53:58 markus 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 */ 58 extern char *client_version_string; 59 extern char *server_version_string; 60 extern Options options; 61 62 /* 63 * SSH2 key exchange 64 */ 65 66 u_char *session_id2 = NULL; 67 u_int session_id2_len = 0; 68 69 char *xxx_host; 70 struct sockaddr *xxx_hostaddr; 71 72 Kex *xxx_kex = NULL; 73 74 static int 75 verify_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 82 void 83 ssh_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 */ 147 148 typedef struct Authctxt Authctxt; 149 typedef struct Authmethod Authmethod; 150 typedef struct identity Identity; 151 typedef struct idlist Idlist; 152 153 struct 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 }; 161 TAILQ_HEAD(idlist, identity); 162 163 struct 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 }; 181 struct 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 }; 187 188 void input_userauth_success(int, u_int32_t, void *); 189 void input_userauth_failure(int, u_int32_t, void *); 190 void input_userauth_banner(int, u_int32_t, void *); 191 void input_userauth_error(int, u_int32_t, void *); 192 void input_userauth_info_req(int, u_int32_t, void *); 193 void input_userauth_pk_ok(int, u_int32_t, void *); 194 void input_userauth_passwd_changereq(int, u_int32_t, void *); 195 196 int userauth_none(Authctxt *); 197 int userauth_pubkey(Authctxt *); 198 int userauth_passwd(Authctxt *); 199 int userauth_kbdint(Authctxt *); 200 int userauth_hostbased(Authctxt *); 201 int userauth_kerberos(Authctxt *); 202 203 #ifdef GSSAPI 204 int userauth_gssapi(Authctxt *authctxt); 205 void input_gssapi_response(int type, u_int32_t, void *); 206 void input_gssapi_token(int type, u_int32_t, void *); 207 void input_gssapi_hash(int type, u_int32_t, void *); 208 void input_gssapi_error(int, u_int32_t, void *); 209 void input_gssapi_errtok(int, u_int32_t, void *); 210 #endif 211 212 void userauth(Authctxt *, char *); 213 214 static int sign_and_send_pubkey(Authctxt *, Identity *); 215 static void pubkey_prepare(Authctxt *); 216 static void pubkey_cleanup(Authctxt *); 217 static Key *load_identity_file(char *); 218 219 static Authmethod *authmethod_get(char *authlist); 220 static Authmethod *authmethod_lookup(const char *name); 221 static char *authmethods_get(void); 222 223 Authmethod authmethods[] = { 224 #ifdef GSSAPI 225 {"gssapi-with-mic", 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 }; 252 253 void 254 ssh_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 } 314 315 void 316 userauth(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 } 349 350 void 351 input_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 } 356 357 void 358 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 359 { 360 char *msg, *lang; 361 362 debug3("input_userauth_banner"); 363 msg = packet_get_string(NULL); 364 lang = packet_get_string(NULL); 365 if (options.log_level > SYSLOG_LEVEL_QUIET) 366 fprintf(stderr, "%s", msg); 367 xfree(msg); 368 xfree(lang); 369 } 370 371 void 372 input_userauth_success(int type, u_int32_t seq, void *ctxt) 373 { 374 Authctxt *authctxt = ctxt; 375 if (authctxt == NULL) 376 fatal("input_userauth_success: no authentication context"); 377 if (authctxt->authlist) { 378 xfree(authctxt->authlist); 379 authctxt->authlist = NULL; 380 } 381 if (authctxt->methoddata) { 382 xfree(authctxt->methoddata); 383 authctxt->methoddata = NULL; 384 } 385 authctxt->success = 1; /* break out */ 386 } 387 388 void 389 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 390 { 391 Authctxt *authctxt = ctxt; 392 char *authlist = NULL; 393 int partial; 394 395 if (authctxt == NULL) 396 fatal("input_userauth_failure: no authentication context"); 397 398 authlist = packet_get_string(NULL); 399 partial = packet_get_char(); 400 packet_check_eom(); 401 402 if (partial != 0) 403 logit("Authenticated with partial success."); 404 debug("Authentications that can continue: %s", authlist); 405 406 userauth(authctxt, authlist); 407 } 408 void 409 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 410 { 411 Authctxt *authctxt = ctxt; 412 Key *key = NULL; 413 Identity *id = NULL; 414 Buffer b; 415 int pktype, sent = 0; 416 u_int alen, blen; 417 char *pkalg, *fp; 418 u_char *pkblob; 419 420 if (authctxt == NULL) 421 fatal("input_userauth_pk_ok: no authentication context"); 422 if (datafellows & SSH_BUG_PKOK) { 423 /* this is similar to SSH_BUG_PKAUTH */ 424 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 425 pkblob = packet_get_string(&blen); 426 buffer_init(&b); 427 buffer_append(&b, pkblob, blen); 428 pkalg = buffer_get_string(&b, &alen); 429 buffer_free(&b); 430 } else { 431 pkalg = packet_get_string(&alen); 432 pkblob = packet_get_string(&blen); 433 } 434 packet_check_eom(); 435 436 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 437 438 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 439 debug("unknown pkalg %s", pkalg); 440 goto done; 441 } 442 if ((key = key_from_blob(pkblob, blen)) == NULL) { 443 debug("no key from blob. pkalg %s", pkalg); 444 goto done; 445 } 446 if (key->type != pktype) { 447 error("input_userauth_pk_ok: type mismatch " 448 "for decoded key (received %d, expected %d)", 449 key->type, pktype); 450 goto done; 451 } 452 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 453 debug2("input_userauth_pk_ok: fp %s", fp); 454 xfree(fp); 455 456 /* 457 * search keys in the reverse order, because last candidate has been 458 * moved to the end of the queue. this also avoids confusion by 459 * duplicate keys 460 */ 461 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, next, idlist) { 462 if (key_equal(key, id->key)) { 463 sent = sign_and_send_pubkey(authctxt, id); 464 break; 465 } 466 } 467 done: 468 if (key != NULL) 469 key_free(key); 470 xfree(pkalg); 471 xfree(pkblob); 472 473 /* try another method if we did not send a packet */ 474 if (sent == 0) 475 userauth(authctxt, NULL); 476 } 477 478 #ifdef GSSAPI 479 int 480 userauth_gssapi(Authctxt *authctxt) 481 { 482 Gssctxt *gssctxt = NULL; 483 static gss_OID_set gss_supported = NULL; 484 static int mech = 0; 485 OM_uint32 min; 486 int ok = 0; 487 488 /* Try one GSSAPI method at a time, rather than sending them all at 489 * once. */ 490 491 if (gss_supported == NULL) 492 gss_indicate_mechs(&min, &gss_supported); 493 494 /* Check to see if the mechanism is usable before we offer it */ 495 while (mech < gss_supported->count && !ok) { 496 if (gssctxt) 497 ssh_gssapi_delete_ctx(&gssctxt); 498 ssh_gssapi_build_ctx(&gssctxt); 499 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]); 500 501 /* My DER encoding requires length<128 */ 502 if (gss_supported->elements[mech].length < 128 && 503 !GSS_ERROR(ssh_gssapi_import_name(gssctxt, 504 authctxt->host))) { 505 ok = 1; /* Mechanism works */ 506 } else { 507 mech++; 508 } 509 } 510 511 if (!ok) return 0; 512 513 authctxt->methoddata=(void *)gssctxt; 514 515 packet_start(SSH2_MSG_USERAUTH_REQUEST); 516 packet_put_cstring(authctxt->server_user); 517 packet_put_cstring(authctxt->service); 518 packet_put_cstring(authctxt->method->name); 519 520 packet_put_int(1); 521 522 packet_put_int((gss_supported->elements[mech].length) + 2); 523 packet_put_char(SSH_GSS_OIDTYPE); 524 packet_put_char(gss_supported->elements[mech].length); 525 packet_put_raw(gss_supported->elements[mech].elements, 526 gss_supported->elements[mech].length); 527 528 packet_send(); 529 530 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 531 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 532 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 533 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 534 535 mech++; /* Move along to next candidate */ 536 537 return 1; 538 } 539 540 static OM_uint32 541 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 542 { 543 Authctxt *authctxt = ctxt; 544 Gssctxt *gssctxt = authctxt->methoddata; 545 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 546 gss_buffer_desc gssbuf, mic; 547 OM_uint32 status, ms, flags; 548 Buffer b; 549 550 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 551 recv_tok, &send_tok, &flags); 552 553 if (send_tok.length > 0) { 554 if (GSS_ERROR(status)) 555 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 556 else 557 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 558 559 packet_put_string(send_tok.value, send_tok.length); 560 packet_send(); 561 gss_release_buffer(&ms, &send_tok); 562 } 563 564 if (status == GSS_S_COMPLETE) { 565 /* send either complete or MIC, depending on mechanism */ 566 if (!(flags & GSS_C_INTEG_FLAG)) { 567 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 568 packet_send(); 569 } else { 570 ssh_gssapi_buildmic(&b, authctxt->server_user, 571 authctxt->service, "gssapi-with-mic"); 572 573 gssbuf.value = buffer_ptr(&b); 574 gssbuf.length = buffer_len(&b); 575 576 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 577 578 if (!GSS_ERROR(status)) { 579 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 580 packet_put_string(mic.value, mic.length); 581 582 packet_send(); 583 } 584 585 buffer_free(&b); 586 gss_release_buffer(&ms, &mic); 587 } 588 } 589 590 return status; 591 } 592 593 void 594 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 595 { 596 Authctxt *authctxt = ctxt; 597 Gssctxt *gssctxt; 598 int oidlen; 599 char *oidv; 600 601 if (authctxt == NULL) 602 fatal("input_gssapi_response: no authentication context"); 603 gssctxt = authctxt->methoddata; 604 605 /* Setup our OID */ 606 oidv = packet_get_string(&oidlen); 607 608 if (oidlen <= 2 || 609 oidv[0] != SSH_GSS_OIDTYPE || 610 oidv[1] != oidlen - 2) { 611 xfree(oidv); 612 debug("Badly encoded mechanism OID received"); 613 userauth(authctxt, NULL); 614 return; 615 } 616 617 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 618 fatal("Server returned different OID than expected"); 619 620 packet_check_eom(); 621 622 xfree(oidv); 623 624 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 625 /* Start again with next method on list */ 626 debug("Trying to start again"); 627 userauth(authctxt, NULL); 628 return; 629 } 630 } 631 632 void 633 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 634 { 635 Authctxt *authctxt = ctxt; 636 gss_buffer_desc recv_tok; 637 OM_uint32 status; 638 u_int slen; 639 640 if (authctxt == NULL) 641 fatal("input_gssapi_response: no authentication context"); 642 643 recv_tok.value = packet_get_string(&slen); 644 recv_tok.length = slen; /* safe typecast */ 645 646 packet_check_eom(); 647 648 status = process_gssapi_token(ctxt, &recv_tok); 649 650 xfree(recv_tok.value); 651 652 if (GSS_ERROR(status)) { 653 /* Start again with the next method in the list */ 654 userauth(authctxt, NULL); 655 return; 656 } 657 } 658 659 void 660 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 661 { 662 Authctxt *authctxt = ctxt; 663 Gssctxt *gssctxt; 664 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 665 gss_buffer_desc recv_tok; 666 OM_uint32 status, ms; 667 u_int len; 668 669 if (authctxt == NULL) 670 fatal("input_gssapi_response: no authentication context"); 671 gssctxt = authctxt->methoddata; 672 673 recv_tok.value = packet_get_string(&len); 674 recv_tok.length = len; 675 676 packet_check_eom(); 677 678 /* Stick it into GSSAPI and see what it says */ 679 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 680 &recv_tok, &send_tok, NULL); 681 682 xfree(recv_tok.value); 683 gss_release_buffer(&ms, &send_tok); 684 685 /* Server will be returning a failed packet after this one */ 686 } 687 688 void 689 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 690 { 691 OM_uint32 maj, min; 692 char *msg; 693 char *lang; 694 695 maj=packet_get_int(); 696 min=packet_get_int(); 697 msg=packet_get_string(NULL); 698 lang=packet_get_string(NULL); 699 700 packet_check_eom(); 701 702 debug("Server GSSAPI Error:\n%s\n", msg); 703 xfree(msg); 704 xfree(lang); 705 } 706 #endif /* GSSAPI */ 707 708 int 709 userauth_none(Authctxt *authctxt) 710 { 711 /* initial userauth request */ 712 packet_start(SSH2_MSG_USERAUTH_REQUEST); 713 packet_put_cstring(authctxt->server_user); 714 packet_put_cstring(authctxt->service); 715 packet_put_cstring(authctxt->method->name); 716 packet_send(); 717 return 1; 718 } 719 720 int 721 userauth_passwd(Authctxt *authctxt) 722 { 723 static int attempt = 0; 724 char prompt[150]; 725 char *password; 726 727 if (attempt++ >= options.number_of_password_prompts) 728 return 0; 729 730 if (attempt != 1) 731 error("Permission denied, please try again."); 732 733 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 734 authctxt->server_user, authctxt->host); 735 password = read_passphrase(prompt, 0); 736 packet_start(SSH2_MSG_USERAUTH_REQUEST); 737 packet_put_cstring(authctxt->server_user); 738 packet_put_cstring(authctxt->service); 739 packet_put_cstring(authctxt->method->name); 740 packet_put_char(0); 741 packet_put_cstring(password); 742 memset(password, 0, strlen(password)); 743 xfree(password); 744 packet_add_padding(64); 745 packet_send(); 746 747 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 748 &input_userauth_passwd_changereq); 749 750 return 1; 751 } 752 /* 753 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 754 */ 755 void 756 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 757 { 758 Authctxt *authctxt = ctxt; 759 char *info, *lang, *password = NULL, *retype = NULL; 760 char prompt[150]; 761 762 debug2("input_userauth_passwd_changereq"); 763 764 if (authctxt == NULL) 765 fatal("input_userauth_passwd_changereq: " 766 "no authentication context"); 767 768 info = packet_get_string(NULL); 769 lang = packet_get_string(NULL); 770 if (strlen(info) > 0) 771 logit("%s", info); 772 xfree(info); 773 xfree(lang); 774 packet_start(SSH2_MSG_USERAUTH_REQUEST); 775 packet_put_cstring(authctxt->server_user); 776 packet_put_cstring(authctxt->service); 777 packet_put_cstring(authctxt->method->name); 778 packet_put_char(1); /* additional info */ 779 snprintf(prompt, sizeof(prompt), 780 "Enter %.30s@%.128s's old password: ", 781 authctxt->server_user, authctxt->host); 782 password = read_passphrase(prompt, 0); 783 packet_put_cstring(password); 784 memset(password, 0, strlen(password)); 785 xfree(password); 786 password = NULL; 787 while (password == NULL) { 788 snprintf(prompt, sizeof(prompt), 789 "Enter %.30s@%.128s's new password: ", 790 authctxt->server_user, authctxt->host); 791 password = read_passphrase(prompt, RP_ALLOW_EOF); 792 if (password == NULL) { 793 /* bail out */ 794 return; 795 } 796 snprintf(prompt, sizeof(prompt), 797 "Retype %.30s@%.128s's new password: ", 798 authctxt->server_user, authctxt->host); 799 retype = read_passphrase(prompt, 0); 800 if (strcmp(password, retype) != 0) { 801 memset(password, 0, strlen(password)); 802 xfree(password); 803 logit("Mismatch; try again, EOF to quit."); 804 password = NULL; 805 } 806 memset(retype, 0, strlen(retype)); 807 xfree(retype); 808 } 809 packet_put_cstring(password); 810 memset(password, 0, strlen(password)); 811 xfree(password); 812 packet_add_padding(64); 813 packet_send(); 814 815 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 816 &input_userauth_passwd_changereq); 817 } 818 819 static int 820 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 821 u_char *data, u_int datalen) 822 { 823 Key *prv; 824 int ret; 825 826 /* the agent supports this key */ 827 if (id->ac) 828 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 829 data, datalen)); 830 /* 831 * we have already loaded the private key or 832 * the private key is stored in external hardware 833 */ 834 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 835 return (key_sign(id->key, sigp, lenp, data, datalen)); 836 /* load the private key from the file */ 837 if ((prv = load_identity_file(id->filename)) == NULL) 838 return (-1); 839 ret = key_sign(prv, sigp, lenp, data, datalen); 840 key_free(prv); 841 return (ret); 842 } 843 844 static int 845 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 846 { 847 Buffer b; 848 u_char *blob, *signature; 849 u_int bloblen, slen; 850 u_int skip = 0; 851 int ret = -1; 852 int have_sig = 1; 853 854 debug3("sign_and_send_pubkey"); 855 856 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 857 /* we cannot handle this key */ 858 debug3("sign_and_send_pubkey: cannot handle key"); 859 return 0; 860 } 861 /* data to be signed */ 862 buffer_init(&b); 863 if (datafellows & SSH_OLD_SESSIONID) { 864 buffer_append(&b, session_id2, session_id2_len); 865 skip = session_id2_len; 866 } else { 867 buffer_put_string(&b, session_id2, session_id2_len); 868 skip = buffer_len(&b); 869 } 870 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 871 buffer_put_cstring(&b, authctxt->server_user); 872 buffer_put_cstring(&b, 873 datafellows & SSH_BUG_PKSERVICE ? 874 "ssh-userauth" : 875 authctxt->service); 876 if (datafellows & SSH_BUG_PKAUTH) { 877 buffer_put_char(&b, have_sig); 878 } else { 879 buffer_put_cstring(&b, authctxt->method->name); 880 buffer_put_char(&b, have_sig); 881 buffer_put_cstring(&b, key_ssh_name(id->key)); 882 } 883 buffer_put_string(&b, blob, bloblen); 884 885 /* generate signature */ 886 ret = identity_sign(id, &signature, &slen, 887 buffer_ptr(&b), buffer_len(&b)); 888 if (ret == -1) { 889 xfree(blob); 890 buffer_free(&b); 891 return 0; 892 } 893 #ifdef DEBUG_PK 894 buffer_dump(&b); 895 #endif 896 if (datafellows & SSH_BUG_PKSERVICE) { 897 buffer_clear(&b); 898 buffer_append(&b, session_id2, session_id2_len); 899 skip = session_id2_len; 900 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 901 buffer_put_cstring(&b, authctxt->server_user); 902 buffer_put_cstring(&b, authctxt->service); 903 buffer_put_cstring(&b, authctxt->method->name); 904 buffer_put_char(&b, have_sig); 905 if (!(datafellows & SSH_BUG_PKAUTH)) 906 buffer_put_cstring(&b, key_ssh_name(id->key)); 907 buffer_put_string(&b, blob, bloblen); 908 } 909 xfree(blob); 910 911 /* append signature */ 912 buffer_put_string(&b, signature, slen); 913 xfree(signature); 914 915 /* skip session id and packet type */ 916 if (buffer_len(&b) < skip + 1) 917 fatal("userauth_pubkey: internal error"); 918 buffer_consume(&b, skip + 1); 919 920 /* put remaining data from buffer into packet */ 921 packet_start(SSH2_MSG_USERAUTH_REQUEST); 922 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 923 buffer_free(&b); 924 packet_send(); 925 926 return 1; 927 } 928 929 static int 930 send_pubkey_test(Authctxt *authctxt, Identity *id) 931 { 932 u_char *blob; 933 u_int bloblen, have_sig = 0; 934 935 debug3("send_pubkey_test"); 936 937 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 938 /* we cannot handle this key */ 939 debug3("send_pubkey_test: cannot handle key"); 940 return 0; 941 } 942 /* register callback for USERAUTH_PK_OK message */ 943 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 944 945 packet_start(SSH2_MSG_USERAUTH_REQUEST); 946 packet_put_cstring(authctxt->server_user); 947 packet_put_cstring(authctxt->service); 948 packet_put_cstring(authctxt->method->name); 949 packet_put_char(have_sig); 950 if (!(datafellows & SSH_BUG_PKAUTH)) 951 packet_put_cstring(key_ssh_name(id->key)); 952 packet_put_string(blob, bloblen); 953 xfree(blob); 954 packet_send(); 955 return 1; 956 } 957 958 static Key * 959 load_identity_file(char *filename) 960 { 961 Key *private; 962 char prompt[300], *passphrase; 963 int quit, i; 964 struct stat st; 965 966 if (stat(filename, &st) < 0) { 967 debug3("no such identity: %s", filename); 968 return NULL; 969 } 970 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); 971 if (private == NULL) { 972 if (options.batch_mode) 973 return NULL; 974 snprintf(prompt, sizeof prompt, 975 "Enter passphrase for key '%.100s': ", filename); 976 for (i = 0; i < options.number_of_password_prompts; i++) { 977 passphrase = read_passphrase(prompt, 0); 978 if (strcmp(passphrase, "") != 0) { 979 private = key_load_private_type(KEY_UNSPEC, filename, 980 passphrase, NULL); 981 quit = 0; 982 } else { 983 debug2("no passphrase given, try next key"); 984 quit = 1; 985 } 986 memset(passphrase, 0, strlen(passphrase)); 987 xfree(passphrase); 988 if (private != NULL || quit) 989 break; 990 debug2("bad passphrase given, try again..."); 991 } 992 } 993 return private; 994 } 995 996 /* 997 * try keys in the following order: 998 * 1. agent keys that are found in the config file 999 * 2. other agent keys 1000 * 3. keys that are only listed in the config file 1001 */ 1002 static void 1003 pubkey_prepare(Authctxt *authctxt) 1004 { 1005 Identity *id; 1006 Idlist agent, files, *preferred; 1007 Key *key; 1008 AuthenticationConnection *ac; 1009 char *comment; 1010 int i, found; 1011 1012 TAILQ_INIT(&agent); /* keys from the agent */ 1013 TAILQ_INIT(&files); /* keys from the config file */ 1014 preferred = &authctxt->keys; 1015 TAILQ_INIT(preferred); /* preferred order of keys */ 1016 1017 /* list of keys stored in the filesystem */ 1018 for (i = 0; i < options.num_identity_files; i++) { 1019 key = options.identity_keys[i]; 1020 if (key && key->type == KEY_RSA1) 1021 continue; 1022 options.identity_keys[i] = NULL; 1023 id = xmalloc(sizeof(*id)); 1024 memset(id, 0, sizeof(*id)); 1025 id->key = key; 1026 id->filename = xstrdup(options.identity_files[i]); 1027 TAILQ_INSERT_TAIL(&files, id, next); 1028 } 1029 /* list of keys supported by the agent */ 1030 if ((ac = ssh_get_authentication_connection())) { 1031 for (key = ssh_get_first_identity(ac, &comment, 2); 1032 key != NULL; 1033 key = ssh_get_next_identity(ac, &comment, 2)) { 1034 found = 0; 1035 TAILQ_FOREACH(id, &files, next) { 1036 /* agent keys from the config file are preferred */ 1037 if (key_equal(key, id->key)) { 1038 key_free(key); 1039 xfree(comment); 1040 TAILQ_REMOVE(&files, id, next); 1041 TAILQ_INSERT_TAIL(preferred, id, next); 1042 id->ac = ac; 1043 found = 1; 1044 break; 1045 } 1046 } 1047 if (!found && !options.identities_only) { 1048 id = xmalloc(sizeof(*id)); 1049 memset(id, 0, sizeof(*id)); 1050 id->key = key; 1051 id->filename = comment; 1052 id->ac = ac; 1053 TAILQ_INSERT_TAIL(&agent, id, next); 1054 } 1055 } 1056 /* append remaining agent keys */ 1057 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1058 TAILQ_REMOVE(&agent, id, next); 1059 TAILQ_INSERT_TAIL(preferred, id, next); 1060 } 1061 authctxt->agent = ac; 1062 } 1063 /* append remaining keys from the config file */ 1064 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1065 TAILQ_REMOVE(&files, id, next); 1066 TAILQ_INSERT_TAIL(preferred, id, next); 1067 } 1068 TAILQ_FOREACH(id, preferred, next) { 1069 debug2("key: %s (%p)", id->filename, id->key); 1070 } 1071 } 1072 1073 static void 1074 pubkey_cleanup(Authctxt *authctxt) 1075 { 1076 Identity *id; 1077 1078 if (authctxt->agent != NULL) 1079 ssh_close_authentication_connection(authctxt->agent); 1080 for (id = TAILQ_FIRST(&authctxt->keys); id; 1081 id = TAILQ_FIRST(&authctxt->keys)) { 1082 TAILQ_REMOVE(&authctxt->keys, id, next); 1083 if (id->key) 1084 key_free(id->key); 1085 if (id->filename) 1086 xfree(id->filename); 1087 xfree(id); 1088 } 1089 } 1090 1091 int 1092 userauth_pubkey(Authctxt *authctxt) 1093 { 1094 Identity *id; 1095 int sent = 0; 1096 1097 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1098 if (id->tried++) 1099 return (0); 1100 /* move key to the end of the queue */ 1101 TAILQ_REMOVE(&authctxt->keys, id, next); 1102 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1103 /* 1104 * send a test message if we have the public key. for 1105 * encrypted keys we cannot do this and have to load the 1106 * private key instead 1107 */ 1108 if (id->key && id->key->type != KEY_RSA1) { 1109 debug("Offering public key: %s", id->filename); 1110 sent = send_pubkey_test(authctxt, id); 1111 } else if (id->key == NULL) { 1112 debug("Trying private key: %s", id->filename); 1113 id->key = load_identity_file(id->filename); 1114 if (id->key != NULL) { 1115 id->isprivate = 1; 1116 sent = sign_and_send_pubkey(authctxt, id); 1117 key_free(id->key); 1118 id->key = NULL; 1119 } 1120 } 1121 if (sent) 1122 return (sent); 1123 } 1124 return (0); 1125 } 1126 1127 /* 1128 * Send userauth request message specifying keyboard-interactive method. 1129 */ 1130 int 1131 userauth_kbdint(Authctxt *authctxt) 1132 { 1133 static int attempt = 0; 1134 1135 if (attempt++ >= options.number_of_password_prompts) 1136 return 0; 1137 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1138 if (attempt > 1 && !authctxt->info_req_seen) { 1139 debug3("userauth_kbdint: disable: no info_req_seen"); 1140 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1141 return 0; 1142 } 1143 1144 debug2("userauth_kbdint"); 1145 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1146 packet_put_cstring(authctxt->server_user); 1147 packet_put_cstring(authctxt->service); 1148 packet_put_cstring(authctxt->method->name); 1149 packet_put_cstring(""); /* lang */ 1150 packet_put_cstring(options.kbd_interactive_devices ? 1151 options.kbd_interactive_devices : ""); 1152 packet_send(); 1153 1154 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1155 return 1; 1156 } 1157 1158 /* 1159 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1160 */ 1161 void 1162 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1163 { 1164 Authctxt *authctxt = ctxt; 1165 char *name, *inst, *lang, *prompt, *response; 1166 u_int num_prompts, i; 1167 int echo = 0; 1168 1169 debug2("input_userauth_info_req"); 1170 1171 if (authctxt == NULL) 1172 fatal("input_userauth_info_req: no authentication context"); 1173 1174 authctxt->info_req_seen = 1; 1175 1176 name = packet_get_string(NULL); 1177 inst = packet_get_string(NULL); 1178 lang = packet_get_string(NULL); 1179 if (strlen(name) > 0) 1180 logit("%s", name); 1181 if (strlen(inst) > 0) 1182 logit("%s", inst); 1183 xfree(name); 1184 xfree(inst); 1185 xfree(lang); 1186 1187 num_prompts = packet_get_int(); 1188 /* 1189 * Begin to build info response packet based on prompts requested. 1190 * We commit to providing the correct number of responses, so if 1191 * further on we run into a problem that prevents this, we have to 1192 * be sure and clean this up and send a correct error response. 1193 */ 1194 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1195 packet_put_int(num_prompts); 1196 1197 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1198 for (i = 0; i < num_prompts; i++) { 1199 prompt = packet_get_string(NULL); 1200 echo = packet_get_char(); 1201 1202 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1203 1204 packet_put_cstring(response); 1205 memset(response, 0, strlen(response)); 1206 xfree(response); 1207 xfree(prompt); 1208 } 1209 packet_check_eom(); /* done with parsing incoming message. */ 1210 1211 packet_add_padding(64); 1212 packet_send(); 1213 } 1214 1215 static int 1216 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1217 u_char *data, u_int datalen) 1218 { 1219 Buffer b; 1220 struct stat st; 1221 pid_t pid; 1222 int to[2], from[2], status, version = 2; 1223 1224 debug2("ssh_keysign called"); 1225 1226 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1227 error("ssh_keysign: no installed: %s", strerror(errno)); 1228 return -1; 1229 } 1230 if (fflush(stdout) != 0) 1231 error("ssh_keysign: fflush: %s", strerror(errno)); 1232 if (pipe(to) < 0) { 1233 error("ssh_keysign: pipe: %s", strerror(errno)); 1234 return -1; 1235 } 1236 if (pipe(from) < 0) { 1237 error("ssh_keysign: pipe: %s", strerror(errno)); 1238 return -1; 1239 } 1240 if ((pid = fork()) < 0) { 1241 error("ssh_keysign: fork: %s", strerror(errno)); 1242 return -1; 1243 } 1244 if (pid == 0) { 1245 seteuid(getuid()); 1246 setuid(getuid()); 1247 close(from[0]); 1248 if (dup2(from[1], STDOUT_FILENO) < 0) 1249 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1250 close(to[1]); 1251 if (dup2(to[0], STDIN_FILENO) < 0) 1252 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1253 close(from[1]); 1254 close(to[0]); 1255 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1256 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1257 strerror(errno)); 1258 } 1259 close(from[1]); 1260 close(to[0]); 1261 1262 buffer_init(&b); 1263 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1264 buffer_put_string(&b, data, datalen); 1265 if (ssh_msg_send(to[1], version, &b) == -1) 1266 fatal("ssh_keysign: couldn't send request"); 1267 1268 if (ssh_msg_recv(from[0], &b) < 0) { 1269 error("ssh_keysign: no reply"); 1270 buffer_free(&b); 1271 return -1; 1272 } 1273 close(from[0]); 1274 close(to[1]); 1275 1276 while (waitpid(pid, &status, 0) < 0) 1277 if (errno != EINTR) 1278 break; 1279 1280 if (buffer_get_char(&b) != version) { 1281 error("ssh_keysign: bad version"); 1282 buffer_free(&b); 1283 return -1; 1284 } 1285 *sigp = buffer_get_string(&b, lenp); 1286 buffer_free(&b); 1287 1288 return 0; 1289 } 1290 1291 int 1292 userauth_hostbased(Authctxt *authctxt) 1293 { 1294 Key *private = NULL; 1295 Sensitive *sensitive = authctxt->sensitive; 1296 Buffer b; 1297 u_char *signature, *blob; 1298 char *chost, *pkalg, *p; 1299 const char *service; 1300 u_int blen, slen; 1301 int ok, i, len, found = 0; 1302 1303 /* check for a useful key */ 1304 for (i = 0; i < sensitive->nkeys; i++) { 1305 private = sensitive->keys[i]; 1306 if (private && private->type != KEY_RSA1) { 1307 found = 1; 1308 /* we take and free the key */ 1309 sensitive->keys[i] = NULL; 1310 break; 1311 } 1312 } 1313 if (!found) { 1314 debug("No more client hostkeys for hostbased authentication."); 1315 return 0; 1316 } 1317 if (key_to_blob(private, &blob, &blen) == 0) { 1318 key_free(private); 1319 return 0; 1320 } 1321 /* figure out a name for the client host */ 1322 p = get_local_name(packet_get_connection_in()); 1323 if (p == NULL) { 1324 error("userauth_hostbased: cannot get local ipaddr/name"); 1325 key_free(private); 1326 return 0; 1327 } 1328 len = strlen(p) + 2; 1329 chost = xmalloc(len); 1330 strlcpy(chost, p, len); 1331 strlcat(chost, ".", len); 1332 debug2("userauth_hostbased: chost %s", chost); 1333 xfree(p); 1334 1335 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1336 authctxt->service; 1337 pkalg = xstrdup(key_ssh_name(private)); 1338 buffer_init(&b); 1339 /* construct data */ 1340 buffer_put_string(&b, session_id2, session_id2_len); 1341 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1342 buffer_put_cstring(&b, authctxt->server_user); 1343 buffer_put_cstring(&b, service); 1344 buffer_put_cstring(&b, authctxt->method->name); 1345 buffer_put_cstring(&b, pkalg); 1346 buffer_put_string(&b, blob, blen); 1347 buffer_put_cstring(&b, chost); 1348 buffer_put_cstring(&b, authctxt->local_user); 1349 #ifdef DEBUG_PK 1350 buffer_dump(&b); 1351 #endif 1352 if (sensitive->external_keysign) 1353 ok = ssh_keysign(private, &signature, &slen, 1354 buffer_ptr(&b), buffer_len(&b)); 1355 else 1356 ok = key_sign(private, &signature, &slen, 1357 buffer_ptr(&b), buffer_len(&b)); 1358 key_free(private); 1359 buffer_free(&b); 1360 if (ok != 0) { 1361 error("key_sign failed"); 1362 xfree(chost); 1363 xfree(pkalg); 1364 return 0; 1365 } 1366 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1367 packet_put_cstring(authctxt->server_user); 1368 packet_put_cstring(authctxt->service); 1369 packet_put_cstring(authctxt->method->name); 1370 packet_put_cstring(pkalg); 1371 packet_put_string(blob, blen); 1372 packet_put_cstring(chost); 1373 packet_put_cstring(authctxt->local_user); 1374 packet_put_string(signature, slen); 1375 memset(signature, 's', slen); 1376 xfree(signature); 1377 xfree(chost); 1378 xfree(pkalg); 1379 1380 packet_send(); 1381 return 1; 1382 } 1383 1384 /* find auth method */ 1385 1386 /* 1387 * given auth method name, if configurable options permit this method fill 1388 * in auth_ident field and return true, otherwise return false. 1389 */ 1390 static int 1391 authmethod_is_enabled(Authmethod *method) 1392 { 1393 if (method == NULL) 1394 return 0; 1395 /* return false if options indicate this method is disabled */ 1396 if (method->enabled == NULL || *method->enabled == 0) 1397 return 0; 1398 /* return false if batch mode is enabled but method needs interactive mode */ 1399 if (method->batch_flag != NULL && *method->batch_flag != 0) 1400 return 0; 1401 return 1; 1402 } 1403 1404 static Authmethod * 1405 authmethod_lookup(const char *name) 1406 { 1407 Authmethod *method = NULL; 1408 if (name != NULL) 1409 for (method = authmethods; method->name != NULL; method++) 1410 if (strcmp(name, method->name) == 0) 1411 return method; 1412 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1413 return NULL; 1414 } 1415 1416 /* XXX internal state */ 1417 static Authmethod *current = NULL; 1418 static char *supported = NULL; 1419 static char *preferred = NULL; 1420 1421 /* 1422 * Given the authentication method list sent by the server, return the 1423 * next method we should try. If the server initially sends a nil list, 1424 * use a built-in default list. 1425 */ 1426 static Authmethod * 1427 authmethod_get(char *authlist) 1428 { 1429 char *name = NULL; 1430 u_int next; 1431 1432 /* Use a suitable default if we're passed a nil list. */ 1433 if (authlist == NULL || strlen(authlist) == 0) 1434 authlist = options.preferred_authentications; 1435 1436 if (supported == NULL || strcmp(authlist, supported) != 0) { 1437 debug3("start over, passed a different list %s", authlist); 1438 if (supported != NULL) 1439 xfree(supported); 1440 supported = xstrdup(authlist); 1441 preferred = options.preferred_authentications; 1442 debug3("preferred %s", preferred); 1443 current = NULL; 1444 } else if (current != NULL && authmethod_is_enabled(current)) 1445 return current; 1446 1447 for (;;) { 1448 if ((name = match_list(preferred, supported, &next)) == NULL) { 1449 debug("No more authentication methods to try."); 1450 current = NULL; 1451 return NULL; 1452 } 1453 preferred += next; 1454 debug3("authmethod_lookup %s", name); 1455 debug3("remaining preferred: %s", preferred); 1456 if ((current = authmethod_lookup(name)) != NULL && 1457 authmethod_is_enabled(current)) { 1458 debug3("authmethod_is_enabled %s", name); 1459 debug("Next authentication method: %s", name); 1460 return current; 1461 } 1462 } 1463 } 1464 1465 static char * 1466 authmethods_get(void) 1467 { 1468 Authmethod *method = NULL; 1469 Buffer b; 1470 char *list; 1471 1472 buffer_init(&b); 1473 for (method = authmethods; method->name != NULL; method++) { 1474 if (authmethod_is_enabled(method)) { 1475 if (buffer_len(&b) > 0) 1476 buffer_append(&b, ",", 1); 1477 buffer_append(&b, method->name, strlen(method->name)); 1478 } 1479 } 1480 buffer_append(&b, "\0", 1); 1481 list = xstrdup(buffer_ptr(&b)); 1482 buffer_free(&b); 1483 return list; 1484 } 1485