1 /* $OpenBSD: sshconnect2.c,v 1.165 2008/01/19 23:09:49 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include <sys/types.h> 27 #include <sys/socket.h> 28 #include <sys/wait.h> 29 #include <sys/queue.h> 30 #include <sys/stat.h> 31 32 #include <errno.h> 33 #include <netdb.h> 34 #include <stdio.h> 35 #include <string.h> 36 #include <signal.h> 37 #include <pwd.h> 38 #include <unistd.h> 39 40 #include "xmalloc.h" 41 #include "ssh.h" 42 #include "ssh2.h" 43 #include "buffer.h" 44 #include "packet.h" 45 #include "compat.h" 46 #include "cipher.h" 47 #include "key.h" 48 #include "kex.h" 49 #include "myproposal.h" 50 #include "sshconnect.h" 51 #include "authfile.h" 52 #include "dh.h" 53 #include "authfd.h" 54 #include "log.h" 55 #include "readconf.h" 56 #include "misc.h" 57 #include "match.h" 58 #include "dispatch.h" 59 #include "canohost.h" 60 #include "msg.h" 61 #include "pathnames.h" 62 #include "uidswap.h" 63 64 #ifdef GSSAPI 65 #include "ssh-gss.h" 66 #endif 67 68 /* import */ 69 extern char *client_version_string; 70 extern char *server_version_string; 71 extern Options options; 72 73 /* 74 * SSH2 key exchange 75 */ 76 77 u_char *session_id2 = NULL; 78 u_int session_id2_len = 0; 79 80 char *xxx_host; 81 struct sockaddr *xxx_hostaddr; 82 83 Kex *xxx_kex = NULL; 84 85 static int 86 verify_host_key_callback(Key *hostkey) 87 { 88 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 89 fatal("Host key verification failed."); 90 return 0; 91 } 92 93 void 94 ssh_kex2(char *host, struct sockaddr *hostaddr) 95 { 96 Kex *kex; 97 98 xxx_host = host; 99 xxx_hostaddr = hostaddr; 100 101 if (options.ciphers == (char *)-1) { 102 logit("No valid ciphers for protocol version 2 given, using defaults."); 103 options.ciphers = NULL; 104 } 105 if (options.ciphers != NULL) { 106 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 107 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 108 } 109 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 110 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 111 myproposal[PROPOSAL_ENC_ALGS_STOC] = 112 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 113 if (options.compression) { 114 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 115 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 116 } else { 117 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 118 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 119 } 120 if (options.macs != NULL) { 121 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 122 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 123 } 124 if (options.hostkeyalgorithms != NULL) 125 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 126 options.hostkeyalgorithms; 127 128 if (options.rekey_limit) 129 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 130 131 /* start key exchange */ 132 kex = kex_setup(myproposal); 133 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 134 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 135 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 136 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 137 kex->client_version_string=client_version_string; 138 kex->server_version_string=server_version_string; 139 kex->verify_host_key=&verify_host_key_callback; 140 141 xxx_kex = kex; 142 143 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 144 145 session_id2 = kex->session_id; 146 session_id2_len = kex->session_id_len; 147 148 #ifdef DEBUG_KEXDH 149 /* send 1st encrypted/maced/compressed message */ 150 packet_start(SSH2_MSG_IGNORE); 151 packet_put_cstring("markus"); 152 packet_send(); 153 packet_write_wait(); 154 #endif 155 } 156 157 /* 158 * Authenticate user 159 */ 160 161 typedef struct Authctxt Authctxt; 162 typedef struct Authmethod Authmethod; 163 typedef struct identity Identity; 164 typedef struct idlist Idlist; 165 166 struct identity { 167 TAILQ_ENTRY(identity) next; 168 AuthenticationConnection *ac; /* set if agent supports key */ 169 Key *key; /* public/private key */ 170 char *filename; /* comment for agent-only keys */ 171 int tried; 172 int isprivate; /* key points to the private key */ 173 }; 174 TAILQ_HEAD(idlist, identity); 175 176 struct Authctxt { 177 const char *server_user; 178 const char *local_user; 179 const char *host; 180 const char *service; 181 Authmethod *method; 182 int success; 183 char *authlist; 184 /* pubkey */ 185 Idlist keys; 186 AuthenticationConnection *agent; 187 /* hostbased */ 188 Sensitive *sensitive; 189 /* kbd-interactive */ 190 int info_req_seen; 191 /* generic */ 192 void *methoddata; 193 }; 194 struct Authmethod { 195 char *name; /* string to compare against server's list */ 196 int (*userauth)(Authctxt *authctxt); 197 int *enabled; /* flag in option struct that enables method */ 198 int *batch_flag; /* flag in option struct that disables method */ 199 }; 200 201 void input_userauth_success(int, u_int32_t, void *); 202 void input_userauth_failure(int, u_int32_t, void *); 203 void input_userauth_banner(int, u_int32_t, void *); 204 void input_userauth_error(int, u_int32_t, void *); 205 void input_userauth_info_req(int, u_int32_t, void *); 206 void input_userauth_pk_ok(int, u_int32_t, void *); 207 void input_userauth_passwd_changereq(int, u_int32_t, void *); 208 209 int userauth_none(Authctxt *); 210 int userauth_pubkey(Authctxt *); 211 int userauth_passwd(Authctxt *); 212 int userauth_kbdint(Authctxt *); 213 int userauth_hostbased(Authctxt *); 214 int userauth_kerberos(Authctxt *); 215 216 #ifdef GSSAPI 217 int userauth_gssapi(Authctxt *authctxt); 218 void input_gssapi_response(int type, u_int32_t, void *); 219 void input_gssapi_token(int type, u_int32_t, void *); 220 void input_gssapi_hash(int type, u_int32_t, void *); 221 void input_gssapi_error(int, u_int32_t, void *); 222 void input_gssapi_errtok(int, u_int32_t, void *); 223 #endif 224 225 void userauth(Authctxt *, char *); 226 227 static int sign_and_send_pubkey(Authctxt *, Identity *); 228 static void pubkey_prepare(Authctxt *); 229 static void pubkey_cleanup(Authctxt *); 230 static Key *load_identity_file(char *); 231 232 static Authmethod *authmethod_get(char *authlist); 233 static Authmethod *authmethod_lookup(const char *name); 234 static char *authmethods_get(void); 235 236 Authmethod authmethods[] = { 237 #ifdef GSSAPI 238 {"gssapi-with-mic", 239 userauth_gssapi, 240 &options.gss_authentication, 241 NULL}, 242 #endif 243 {"hostbased", 244 userauth_hostbased, 245 &options.hostbased_authentication, 246 NULL}, 247 {"publickey", 248 userauth_pubkey, 249 &options.pubkey_authentication, 250 NULL}, 251 {"keyboard-interactive", 252 userauth_kbdint, 253 &options.kbd_interactive_authentication, 254 &options.batch_mode}, 255 {"password", 256 userauth_passwd, 257 &options.password_authentication, 258 &options.batch_mode}, 259 {"none", 260 userauth_none, 261 NULL, 262 NULL}, 263 {NULL, NULL, NULL, NULL} 264 }; 265 266 void 267 ssh_userauth2(const char *local_user, const char *server_user, char *host, 268 Sensitive *sensitive) 269 { 270 Authctxt authctxt; 271 int type; 272 273 if (options.challenge_response_authentication) 274 options.kbd_interactive_authentication = 1; 275 276 packet_start(SSH2_MSG_SERVICE_REQUEST); 277 packet_put_cstring("ssh-userauth"); 278 packet_send(); 279 debug("SSH2_MSG_SERVICE_REQUEST sent"); 280 packet_write_wait(); 281 type = packet_read(); 282 if (type != SSH2_MSG_SERVICE_ACCEPT) 283 fatal("Server denied authentication request: %d", type); 284 if (packet_remaining() > 0) { 285 char *reply = packet_get_string(NULL); 286 debug2("service_accept: %s", reply); 287 xfree(reply); 288 } else { 289 debug2("buggy server: service_accept w/o service"); 290 } 291 packet_check_eom(); 292 debug("SSH2_MSG_SERVICE_ACCEPT received"); 293 294 if (options.preferred_authentications == NULL) 295 options.preferred_authentications = authmethods_get(); 296 297 /* setup authentication context */ 298 memset(&authctxt, 0, sizeof(authctxt)); 299 pubkey_prepare(&authctxt); 300 authctxt.server_user = server_user; 301 authctxt.local_user = local_user; 302 authctxt.host = host; 303 authctxt.service = "ssh-connection"; /* service name */ 304 authctxt.success = 0; 305 authctxt.method = authmethod_lookup("none"); 306 authctxt.authlist = NULL; 307 authctxt.methoddata = NULL; 308 authctxt.sensitive = sensitive; 309 authctxt.info_req_seen = 0; 310 if (authctxt.method == NULL) 311 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 312 313 /* initial userauth request */ 314 userauth_none(&authctxt); 315 316 dispatch_init(&input_userauth_error); 317 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 318 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 319 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 320 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 321 322 pubkey_cleanup(&authctxt); 323 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 324 325 debug("Authentication succeeded (%s).", authctxt.method->name); 326 } 327 328 void 329 userauth(Authctxt *authctxt, char *authlist) 330 { 331 if (authctxt->methoddata) { 332 xfree(authctxt->methoddata); 333 authctxt->methoddata = NULL; 334 } 335 if (authlist == NULL) { 336 authlist = authctxt->authlist; 337 } else { 338 if (authctxt->authlist) 339 xfree(authctxt->authlist); 340 authctxt->authlist = authlist; 341 } 342 for (;;) { 343 Authmethod *method = authmethod_get(authlist); 344 if (method == NULL) 345 fatal("Permission denied (%s).", authlist); 346 authctxt->method = method; 347 348 /* reset the per method handler */ 349 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 350 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 351 352 /* and try new method */ 353 if (method->userauth(authctxt) != 0) { 354 debug2("we sent a %s packet, wait for reply", method->name); 355 break; 356 } else { 357 debug2("we did not send a packet, disable method"); 358 method->enabled = NULL; 359 } 360 } 361 } 362 363 void 364 input_userauth_error(int type, u_int32_t seq, void *ctxt) 365 { 366 fatal("input_userauth_error: bad message during authentication: " 367 "type %d", type); 368 } 369 370 void 371 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 372 { 373 char *msg, *lang; 374 375 debug3("input_userauth_banner"); 376 msg = packet_get_string(NULL); 377 lang = packet_get_string(NULL); 378 if (options.log_level >= SYSLOG_LEVEL_INFO) 379 fprintf(stderr, "%s", msg); 380 xfree(msg); 381 xfree(lang); 382 } 383 384 void 385 input_userauth_success(int type, u_int32_t seq, void *ctxt) 386 { 387 Authctxt *authctxt = ctxt; 388 if (authctxt == NULL) 389 fatal("input_userauth_success: no authentication context"); 390 if (authctxt->authlist) { 391 xfree(authctxt->authlist); 392 authctxt->authlist = NULL; 393 } 394 if (authctxt->methoddata) { 395 xfree(authctxt->methoddata); 396 authctxt->methoddata = NULL; 397 } 398 authctxt->success = 1; /* break out */ 399 } 400 401 void 402 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 403 { 404 Authctxt *authctxt = ctxt; 405 char *authlist = NULL; 406 int partial; 407 408 if (authctxt == NULL) 409 fatal("input_userauth_failure: no authentication context"); 410 411 authlist = packet_get_string(NULL); 412 partial = packet_get_char(); 413 packet_check_eom(); 414 415 if (partial != 0) 416 logit("Authenticated with partial success."); 417 debug("Authentications that can continue: %s", authlist); 418 419 userauth(authctxt, authlist); 420 } 421 void 422 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 423 { 424 Authctxt *authctxt = ctxt; 425 Key *key = NULL; 426 Identity *id = NULL; 427 Buffer b; 428 int pktype, sent = 0; 429 u_int alen, blen; 430 char *pkalg, *fp; 431 u_char *pkblob; 432 433 if (authctxt == NULL) 434 fatal("input_userauth_pk_ok: no authentication context"); 435 if (datafellows & SSH_BUG_PKOK) { 436 /* this is similar to SSH_BUG_PKAUTH */ 437 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 438 pkblob = packet_get_string(&blen); 439 buffer_init(&b); 440 buffer_append(&b, pkblob, blen); 441 pkalg = buffer_get_string(&b, &alen); 442 buffer_free(&b); 443 } else { 444 pkalg = packet_get_string(&alen); 445 pkblob = packet_get_string(&blen); 446 } 447 packet_check_eom(); 448 449 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 450 451 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 452 debug("unknown pkalg %s", pkalg); 453 goto done; 454 } 455 if ((key = key_from_blob(pkblob, blen)) == NULL) { 456 debug("no key from blob. pkalg %s", pkalg); 457 goto done; 458 } 459 if (key->type != pktype) { 460 error("input_userauth_pk_ok: type mismatch " 461 "for decoded key (received %d, expected %d)", 462 key->type, pktype); 463 goto done; 464 } 465 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 466 debug2("input_userauth_pk_ok: fp %s", fp); 467 xfree(fp); 468 469 /* 470 * search keys in the reverse order, because last candidate has been 471 * moved to the end of the queue. this also avoids confusion by 472 * duplicate keys 473 */ 474 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 475 if (key_equal(key, id->key)) { 476 sent = sign_and_send_pubkey(authctxt, id); 477 break; 478 } 479 } 480 done: 481 if (key != NULL) 482 key_free(key); 483 xfree(pkalg); 484 xfree(pkblob); 485 486 /* try another method if we did not send a packet */ 487 if (sent == 0) 488 userauth(authctxt, NULL); 489 } 490 491 #ifdef GSSAPI 492 int 493 userauth_gssapi(Authctxt *authctxt) 494 { 495 Gssctxt *gssctxt = NULL; 496 static gss_OID_set gss_supported = NULL; 497 static u_int mech = 0; 498 OM_uint32 min; 499 int ok = 0; 500 501 /* Try one GSSAPI method at a time, rather than sending them all at 502 * once. */ 503 504 if (gss_supported == NULL) 505 gss_indicate_mechs(&min, &gss_supported); 506 507 /* Check to see if the mechanism is usable before we offer it */ 508 while (mech < gss_supported->count && !ok) { 509 /* My DER encoding requires length<128 */ 510 if (gss_supported->elements[mech].length < 128 && 511 ssh_gssapi_check_mechanism(&gssctxt, 512 &gss_supported->elements[mech], authctxt->host)) { 513 ok = 1; /* Mechanism works */ 514 } else { 515 mech++; 516 } 517 } 518 519 if (!ok) 520 return 0; 521 522 authctxt->methoddata=(void *)gssctxt; 523 524 packet_start(SSH2_MSG_USERAUTH_REQUEST); 525 packet_put_cstring(authctxt->server_user); 526 packet_put_cstring(authctxt->service); 527 packet_put_cstring(authctxt->method->name); 528 529 packet_put_int(1); 530 531 packet_put_int((gss_supported->elements[mech].length) + 2); 532 packet_put_char(SSH_GSS_OIDTYPE); 533 packet_put_char(gss_supported->elements[mech].length); 534 packet_put_raw(gss_supported->elements[mech].elements, 535 gss_supported->elements[mech].length); 536 537 packet_send(); 538 539 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 540 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 541 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 542 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 543 544 mech++; /* Move along to next candidate */ 545 546 return 1; 547 } 548 549 static OM_uint32 550 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 551 { 552 Authctxt *authctxt = ctxt; 553 Gssctxt *gssctxt = authctxt->methoddata; 554 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 555 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 556 gss_buffer_desc gssbuf; 557 OM_uint32 status, ms, flags; 558 Buffer b; 559 560 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 561 recv_tok, &send_tok, &flags); 562 563 if (send_tok.length > 0) { 564 if (GSS_ERROR(status)) 565 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 566 else 567 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 568 569 packet_put_string(send_tok.value, send_tok.length); 570 packet_send(); 571 gss_release_buffer(&ms, &send_tok); 572 } 573 574 if (status == GSS_S_COMPLETE) { 575 /* send either complete or MIC, depending on mechanism */ 576 if (!(flags & GSS_C_INTEG_FLAG)) { 577 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 578 packet_send(); 579 } else { 580 ssh_gssapi_buildmic(&b, authctxt->server_user, 581 authctxt->service, "gssapi-with-mic"); 582 583 gssbuf.value = buffer_ptr(&b); 584 gssbuf.length = buffer_len(&b); 585 586 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 587 588 if (!GSS_ERROR(status)) { 589 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 590 packet_put_string(mic.value, mic.length); 591 592 packet_send(); 593 } 594 595 buffer_free(&b); 596 gss_release_buffer(&ms, &mic); 597 } 598 } 599 600 return status; 601 } 602 603 void 604 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 605 { 606 Authctxt *authctxt = ctxt; 607 Gssctxt *gssctxt; 608 int oidlen; 609 char *oidv; 610 611 if (authctxt == NULL) 612 fatal("input_gssapi_response: no authentication context"); 613 gssctxt = authctxt->methoddata; 614 615 /* Setup our OID */ 616 oidv = packet_get_string(&oidlen); 617 618 if (oidlen <= 2 || 619 oidv[0] != SSH_GSS_OIDTYPE || 620 oidv[1] != oidlen - 2) { 621 xfree(oidv); 622 debug("Badly encoded mechanism OID received"); 623 userauth(authctxt, NULL); 624 return; 625 } 626 627 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 628 fatal("Server returned different OID than expected"); 629 630 packet_check_eom(); 631 632 xfree(oidv); 633 634 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 635 /* Start again with next method on list */ 636 debug("Trying to start again"); 637 userauth(authctxt, NULL); 638 return; 639 } 640 } 641 642 void 643 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 644 { 645 Authctxt *authctxt = ctxt; 646 gss_buffer_desc recv_tok; 647 OM_uint32 status; 648 u_int slen; 649 650 if (authctxt == NULL) 651 fatal("input_gssapi_response: no authentication context"); 652 653 recv_tok.value = packet_get_string(&slen); 654 recv_tok.length = slen; /* safe typecast */ 655 656 packet_check_eom(); 657 658 status = process_gssapi_token(ctxt, &recv_tok); 659 660 xfree(recv_tok.value); 661 662 if (GSS_ERROR(status)) { 663 /* Start again with the next method in the list */ 664 userauth(authctxt, NULL); 665 return; 666 } 667 } 668 669 void 670 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 671 { 672 Authctxt *authctxt = ctxt; 673 Gssctxt *gssctxt; 674 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 675 gss_buffer_desc recv_tok; 676 OM_uint32 status, ms; 677 u_int len; 678 679 if (authctxt == NULL) 680 fatal("input_gssapi_response: no authentication context"); 681 gssctxt = authctxt->methoddata; 682 683 recv_tok.value = packet_get_string(&len); 684 recv_tok.length = len; 685 686 packet_check_eom(); 687 688 /* Stick it into GSSAPI and see what it says */ 689 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 690 &recv_tok, &send_tok, NULL); 691 692 xfree(recv_tok.value); 693 gss_release_buffer(&ms, &send_tok); 694 695 /* Server will be returning a failed packet after this one */ 696 } 697 698 void 699 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 700 { 701 OM_uint32 maj, min; 702 char *msg; 703 char *lang; 704 705 maj=packet_get_int(); 706 min=packet_get_int(); 707 msg=packet_get_string(NULL); 708 lang=packet_get_string(NULL); 709 710 packet_check_eom(); 711 712 debug("Server GSSAPI Error:\n%s", msg); 713 xfree(msg); 714 xfree(lang); 715 } 716 #endif /* GSSAPI */ 717 718 int 719 userauth_none(Authctxt *authctxt) 720 { 721 /* initial userauth request */ 722 packet_start(SSH2_MSG_USERAUTH_REQUEST); 723 packet_put_cstring(authctxt->server_user); 724 packet_put_cstring(authctxt->service); 725 packet_put_cstring(authctxt->method->name); 726 packet_send(); 727 return 1; 728 } 729 730 int 731 userauth_passwd(Authctxt *authctxt) 732 { 733 static int attempt = 0; 734 char prompt[150]; 735 char *password; 736 737 if (attempt++ >= options.number_of_password_prompts) 738 return 0; 739 740 if (attempt != 1) 741 error("Permission denied, please try again."); 742 743 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 744 authctxt->server_user, authctxt->host); 745 password = read_passphrase(prompt, 0); 746 packet_start(SSH2_MSG_USERAUTH_REQUEST); 747 packet_put_cstring(authctxt->server_user); 748 packet_put_cstring(authctxt->service); 749 packet_put_cstring(authctxt->method->name); 750 packet_put_char(0); 751 packet_put_cstring(password); 752 memset(password, 0, strlen(password)); 753 xfree(password); 754 packet_add_padding(64); 755 packet_send(); 756 757 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 758 &input_userauth_passwd_changereq); 759 760 return 1; 761 } 762 /* 763 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 764 */ 765 void 766 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 767 { 768 Authctxt *authctxt = ctxt; 769 char *info, *lang, *password = NULL, *retype = NULL; 770 char prompt[150]; 771 772 debug2("input_userauth_passwd_changereq"); 773 774 if (authctxt == NULL) 775 fatal("input_userauth_passwd_changereq: " 776 "no authentication context"); 777 778 info = packet_get_string(NULL); 779 lang = packet_get_string(NULL); 780 if (strlen(info) > 0) 781 logit("%s", info); 782 xfree(info); 783 xfree(lang); 784 packet_start(SSH2_MSG_USERAUTH_REQUEST); 785 packet_put_cstring(authctxt->server_user); 786 packet_put_cstring(authctxt->service); 787 packet_put_cstring(authctxt->method->name); 788 packet_put_char(1); /* additional info */ 789 snprintf(prompt, sizeof(prompt), 790 "Enter %.30s@%.128s's old password: ", 791 authctxt->server_user, authctxt->host); 792 password = read_passphrase(prompt, 0); 793 packet_put_cstring(password); 794 memset(password, 0, strlen(password)); 795 xfree(password); 796 password = NULL; 797 while (password == NULL) { 798 snprintf(prompt, sizeof(prompt), 799 "Enter %.30s@%.128s's new password: ", 800 authctxt->server_user, authctxt->host); 801 password = read_passphrase(prompt, RP_ALLOW_EOF); 802 if (password == NULL) { 803 /* bail out */ 804 return; 805 } 806 snprintf(prompt, sizeof(prompt), 807 "Retype %.30s@%.128s's new password: ", 808 authctxt->server_user, authctxt->host); 809 retype = read_passphrase(prompt, 0); 810 if (strcmp(password, retype) != 0) { 811 memset(password, 0, strlen(password)); 812 xfree(password); 813 logit("Mismatch; try again, EOF to quit."); 814 password = NULL; 815 } 816 memset(retype, 0, strlen(retype)); 817 xfree(retype); 818 } 819 packet_put_cstring(password); 820 memset(password, 0, strlen(password)); 821 xfree(password); 822 packet_add_padding(64); 823 packet_send(); 824 825 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 826 &input_userauth_passwd_changereq); 827 } 828 829 static int 830 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 831 u_char *data, u_int datalen) 832 { 833 Key *prv; 834 int ret; 835 836 /* the agent supports this key */ 837 if (id->ac) 838 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 839 data, datalen)); 840 /* 841 * we have already loaded the private key or 842 * the private key is stored in external hardware 843 */ 844 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 845 return (key_sign(id->key, sigp, lenp, data, datalen)); 846 /* load the private key from the file */ 847 if ((prv = load_identity_file(id->filename)) == NULL) 848 return (-1); 849 ret = key_sign(prv, sigp, lenp, data, datalen); 850 key_free(prv); 851 return (ret); 852 } 853 854 static int 855 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 856 { 857 Buffer b; 858 u_char *blob, *signature; 859 u_int bloblen, slen; 860 u_int skip = 0; 861 int ret = -1; 862 int have_sig = 1; 863 864 debug3("sign_and_send_pubkey"); 865 866 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 867 /* we cannot handle this key */ 868 debug3("sign_and_send_pubkey: cannot handle key"); 869 return 0; 870 } 871 /* data to be signed */ 872 buffer_init(&b); 873 if (datafellows & SSH_OLD_SESSIONID) { 874 buffer_append(&b, session_id2, session_id2_len); 875 skip = session_id2_len; 876 } else { 877 buffer_put_string(&b, session_id2, session_id2_len); 878 skip = buffer_len(&b); 879 } 880 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 881 buffer_put_cstring(&b, authctxt->server_user); 882 buffer_put_cstring(&b, 883 datafellows & SSH_BUG_PKSERVICE ? 884 "ssh-userauth" : 885 authctxt->service); 886 if (datafellows & SSH_BUG_PKAUTH) { 887 buffer_put_char(&b, have_sig); 888 } else { 889 buffer_put_cstring(&b, authctxt->method->name); 890 buffer_put_char(&b, have_sig); 891 buffer_put_cstring(&b, key_ssh_name(id->key)); 892 } 893 buffer_put_string(&b, blob, bloblen); 894 895 /* generate signature */ 896 ret = identity_sign(id, &signature, &slen, 897 buffer_ptr(&b), buffer_len(&b)); 898 if (ret == -1) { 899 xfree(blob); 900 buffer_free(&b); 901 return 0; 902 } 903 #ifdef DEBUG_PK 904 buffer_dump(&b); 905 #endif 906 if (datafellows & SSH_BUG_PKSERVICE) { 907 buffer_clear(&b); 908 buffer_append(&b, session_id2, session_id2_len); 909 skip = session_id2_len; 910 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 911 buffer_put_cstring(&b, authctxt->server_user); 912 buffer_put_cstring(&b, authctxt->service); 913 buffer_put_cstring(&b, authctxt->method->name); 914 buffer_put_char(&b, have_sig); 915 if (!(datafellows & SSH_BUG_PKAUTH)) 916 buffer_put_cstring(&b, key_ssh_name(id->key)); 917 buffer_put_string(&b, blob, bloblen); 918 } 919 xfree(blob); 920 921 /* append signature */ 922 buffer_put_string(&b, signature, slen); 923 xfree(signature); 924 925 /* skip session id and packet type */ 926 if (buffer_len(&b) < skip + 1) 927 fatal("userauth_pubkey: internal error"); 928 buffer_consume(&b, skip + 1); 929 930 /* put remaining data from buffer into packet */ 931 packet_start(SSH2_MSG_USERAUTH_REQUEST); 932 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 933 buffer_free(&b); 934 packet_send(); 935 936 return 1; 937 } 938 939 static int 940 send_pubkey_test(Authctxt *authctxt, Identity *id) 941 { 942 u_char *blob; 943 u_int bloblen, have_sig = 0; 944 945 debug3("send_pubkey_test"); 946 947 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 948 /* we cannot handle this key */ 949 debug3("send_pubkey_test: cannot handle key"); 950 return 0; 951 } 952 /* register callback for USERAUTH_PK_OK message */ 953 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 954 955 packet_start(SSH2_MSG_USERAUTH_REQUEST); 956 packet_put_cstring(authctxt->server_user); 957 packet_put_cstring(authctxt->service); 958 packet_put_cstring(authctxt->method->name); 959 packet_put_char(have_sig); 960 if (!(datafellows & SSH_BUG_PKAUTH)) 961 packet_put_cstring(key_ssh_name(id->key)); 962 packet_put_string(blob, bloblen); 963 xfree(blob); 964 packet_send(); 965 return 1; 966 } 967 968 static Key * 969 load_identity_file(char *filename) 970 { 971 Key *private; 972 char prompt[300], *passphrase; 973 int perm_ok, quit, i; 974 struct stat st; 975 976 if (stat(filename, &st) < 0) { 977 debug3("no such identity: %s", filename); 978 return NULL; 979 } 980 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 981 if (!perm_ok) 982 return NULL; 983 if (private == NULL) { 984 if (options.batch_mode) 985 return NULL; 986 snprintf(prompt, sizeof prompt, 987 "Enter passphrase for key '%.100s': ", filename); 988 for (i = 0; i < options.number_of_password_prompts; i++) { 989 passphrase = read_passphrase(prompt, 0); 990 if (strcmp(passphrase, "") != 0) { 991 private = key_load_private_type(KEY_UNSPEC, 992 filename, passphrase, NULL, NULL); 993 quit = 0; 994 } else { 995 debug2("no passphrase given, try next key"); 996 quit = 1; 997 } 998 memset(passphrase, 0, strlen(passphrase)); 999 xfree(passphrase); 1000 if (private != NULL || quit) 1001 break; 1002 debug2("bad passphrase given, try again..."); 1003 } 1004 } 1005 return private; 1006 } 1007 1008 /* 1009 * try keys in the following order: 1010 * 1. agent keys that are found in the config file 1011 * 2. other agent keys 1012 * 3. keys that are only listed in the config file 1013 */ 1014 static void 1015 pubkey_prepare(Authctxt *authctxt) 1016 { 1017 Identity *id; 1018 Idlist agent, files, *preferred; 1019 Key *key; 1020 AuthenticationConnection *ac; 1021 char *comment; 1022 int i, found; 1023 1024 TAILQ_INIT(&agent); /* keys from the agent */ 1025 TAILQ_INIT(&files); /* keys from the config file */ 1026 preferred = &authctxt->keys; 1027 TAILQ_INIT(preferred); /* preferred order of keys */ 1028 1029 /* list of keys stored in the filesystem */ 1030 for (i = 0; i < options.num_identity_files; i++) { 1031 key = options.identity_keys[i]; 1032 if (key && key->type == KEY_RSA1) 1033 continue; 1034 options.identity_keys[i] = NULL; 1035 id = xcalloc(1, sizeof(*id)); 1036 id->key = key; 1037 id->filename = xstrdup(options.identity_files[i]); 1038 TAILQ_INSERT_TAIL(&files, id, next); 1039 } 1040 /* list of keys supported by the agent */ 1041 if ((ac = ssh_get_authentication_connection())) { 1042 for (key = ssh_get_first_identity(ac, &comment, 2); 1043 key != NULL; 1044 key = ssh_get_next_identity(ac, &comment, 2)) { 1045 found = 0; 1046 TAILQ_FOREACH(id, &files, next) { 1047 /* agent keys from the config file are preferred */ 1048 if (key_equal(key, id->key)) { 1049 key_free(key); 1050 xfree(comment); 1051 TAILQ_REMOVE(&files, id, next); 1052 TAILQ_INSERT_TAIL(preferred, id, next); 1053 id->ac = ac; 1054 found = 1; 1055 break; 1056 } 1057 } 1058 if (!found && !options.identities_only) { 1059 id = xcalloc(1, sizeof(*id)); 1060 id->key = key; 1061 id->filename = comment; 1062 id->ac = ac; 1063 TAILQ_INSERT_TAIL(&agent, id, next); 1064 } 1065 } 1066 /* append remaining agent keys */ 1067 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1068 TAILQ_REMOVE(&agent, id, next); 1069 TAILQ_INSERT_TAIL(preferred, id, next); 1070 } 1071 authctxt->agent = ac; 1072 } 1073 /* append remaining keys from the config file */ 1074 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1075 TAILQ_REMOVE(&files, id, next); 1076 TAILQ_INSERT_TAIL(preferred, id, next); 1077 } 1078 TAILQ_FOREACH(id, preferred, next) { 1079 debug2("key: %s (%p)", id->filename, id->key); 1080 } 1081 } 1082 1083 static void 1084 pubkey_cleanup(Authctxt *authctxt) 1085 { 1086 Identity *id; 1087 1088 if (authctxt->agent != NULL) 1089 ssh_close_authentication_connection(authctxt->agent); 1090 for (id = TAILQ_FIRST(&authctxt->keys); id; 1091 id = TAILQ_FIRST(&authctxt->keys)) { 1092 TAILQ_REMOVE(&authctxt->keys, id, next); 1093 if (id->key) 1094 key_free(id->key); 1095 if (id->filename) 1096 xfree(id->filename); 1097 xfree(id); 1098 } 1099 } 1100 1101 int 1102 userauth_pubkey(Authctxt *authctxt) 1103 { 1104 Identity *id; 1105 int sent = 0; 1106 1107 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1108 if (id->tried++) 1109 return (0); 1110 /* move key to the end of the queue */ 1111 TAILQ_REMOVE(&authctxt->keys, id, next); 1112 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1113 /* 1114 * send a test message if we have the public key. for 1115 * encrypted keys we cannot do this and have to load the 1116 * private key instead 1117 */ 1118 if (id->key && id->key->type != KEY_RSA1) { 1119 debug("Offering public key: %s", id->filename); 1120 sent = send_pubkey_test(authctxt, id); 1121 } else if (id->key == NULL) { 1122 debug("Trying private key: %s", id->filename); 1123 id->key = load_identity_file(id->filename); 1124 if (id->key != NULL) { 1125 id->isprivate = 1; 1126 sent = sign_and_send_pubkey(authctxt, id); 1127 key_free(id->key); 1128 id->key = NULL; 1129 } 1130 } 1131 if (sent) 1132 return (sent); 1133 } 1134 return (0); 1135 } 1136 1137 /* 1138 * Send userauth request message specifying keyboard-interactive method. 1139 */ 1140 int 1141 userauth_kbdint(Authctxt *authctxt) 1142 { 1143 static int attempt = 0; 1144 1145 if (attempt++ >= options.number_of_password_prompts) 1146 return 0; 1147 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1148 if (attempt > 1 && !authctxt->info_req_seen) { 1149 debug3("userauth_kbdint: disable: no info_req_seen"); 1150 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1151 return 0; 1152 } 1153 1154 debug2("userauth_kbdint"); 1155 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1156 packet_put_cstring(authctxt->server_user); 1157 packet_put_cstring(authctxt->service); 1158 packet_put_cstring(authctxt->method->name); 1159 packet_put_cstring(""); /* lang */ 1160 packet_put_cstring(options.kbd_interactive_devices ? 1161 options.kbd_interactive_devices : ""); 1162 packet_send(); 1163 1164 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1165 return 1; 1166 } 1167 1168 /* 1169 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1170 */ 1171 void 1172 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1173 { 1174 Authctxt *authctxt = ctxt; 1175 char *name, *inst, *lang, *prompt, *response; 1176 u_int num_prompts, i; 1177 int echo = 0; 1178 1179 debug2("input_userauth_info_req"); 1180 1181 if (authctxt == NULL) 1182 fatal("input_userauth_info_req: no authentication context"); 1183 1184 authctxt->info_req_seen = 1; 1185 1186 name = packet_get_string(NULL); 1187 inst = packet_get_string(NULL); 1188 lang = packet_get_string(NULL); 1189 if (strlen(name) > 0) 1190 logit("%s", name); 1191 if (strlen(inst) > 0) 1192 logit("%s", inst); 1193 xfree(name); 1194 xfree(inst); 1195 xfree(lang); 1196 1197 num_prompts = packet_get_int(); 1198 /* 1199 * Begin to build info response packet based on prompts requested. 1200 * We commit to providing the correct number of responses, so if 1201 * further on we run into a problem that prevents this, we have to 1202 * be sure and clean this up and send a correct error response. 1203 */ 1204 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1205 packet_put_int(num_prompts); 1206 1207 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1208 for (i = 0; i < num_prompts; i++) { 1209 prompt = packet_get_string(NULL); 1210 echo = packet_get_char(); 1211 1212 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1213 1214 packet_put_cstring(response); 1215 memset(response, 0, strlen(response)); 1216 xfree(response); 1217 xfree(prompt); 1218 } 1219 packet_check_eom(); /* done with parsing incoming message. */ 1220 1221 packet_add_padding(64); 1222 packet_send(); 1223 } 1224 1225 static int 1226 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1227 u_char *data, u_int datalen) 1228 { 1229 Buffer b; 1230 struct stat st; 1231 pid_t pid; 1232 int to[2], from[2], status, version = 2; 1233 1234 debug2("ssh_keysign called"); 1235 1236 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1237 error("ssh_keysign: no installed: %s", strerror(errno)); 1238 return -1; 1239 } 1240 if (fflush(stdout) != 0) 1241 error("ssh_keysign: fflush: %s", strerror(errno)); 1242 if (pipe(to) < 0) { 1243 error("ssh_keysign: pipe: %s", strerror(errno)); 1244 return -1; 1245 } 1246 if (pipe(from) < 0) { 1247 error("ssh_keysign: pipe: %s", strerror(errno)); 1248 return -1; 1249 } 1250 if ((pid = fork()) < 0) { 1251 error("ssh_keysign: fork: %s", strerror(errno)); 1252 return -1; 1253 } 1254 if (pid == 0) { 1255 permanently_drop_suid(getuid()); 1256 close(from[0]); 1257 if (dup2(from[1], STDOUT_FILENO) < 0) 1258 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1259 close(to[1]); 1260 if (dup2(to[0], STDIN_FILENO) < 0) 1261 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1262 close(from[1]); 1263 close(to[0]); 1264 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1265 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1266 strerror(errno)); 1267 } 1268 close(from[1]); 1269 close(to[0]); 1270 1271 buffer_init(&b); 1272 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1273 buffer_put_string(&b, data, datalen); 1274 if (ssh_msg_send(to[1], version, &b) == -1) 1275 fatal("ssh_keysign: couldn't send request"); 1276 1277 if (ssh_msg_recv(from[0], &b) < 0) { 1278 error("ssh_keysign: no reply"); 1279 buffer_free(&b); 1280 return -1; 1281 } 1282 close(from[0]); 1283 close(to[1]); 1284 1285 while (waitpid(pid, &status, 0) < 0) 1286 if (errno != EINTR) 1287 break; 1288 1289 if (buffer_get_char(&b) != version) { 1290 error("ssh_keysign: bad version"); 1291 buffer_free(&b); 1292 return -1; 1293 } 1294 *sigp = buffer_get_string(&b, lenp); 1295 buffer_free(&b); 1296 1297 return 0; 1298 } 1299 1300 int 1301 userauth_hostbased(Authctxt *authctxt) 1302 { 1303 Key *private = NULL; 1304 Sensitive *sensitive = authctxt->sensitive; 1305 Buffer b; 1306 u_char *signature, *blob; 1307 char *chost, *pkalg, *p, myname[NI_MAXHOST]; 1308 const char *service; 1309 u_int blen, slen; 1310 int ok, i, len, found = 0; 1311 1312 /* check for a useful key */ 1313 for (i = 0; i < sensitive->nkeys; i++) { 1314 private = sensitive->keys[i]; 1315 if (private && private->type != KEY_RSA1) { 1316 found = 1; 1317 /* we take and free the key */ 1318 sensitive->keys[i] = NULL; 1319 break; 1320 } 1321 } 1322 if (!found) { 1323 debug("No more client hostkeys for hostbased authentication."); 1324 return 0; 1325 } 1326 if (key_to_blob(private, &blob, &blen) == 0) { 1327 key_free(private); 1328 return 0; 1329 } 1330 /* figure out a name for the client host */ 1331 p = NULL; 1332 if (packet_connection_is_on_socket()) 1333 p = get_local_name(packet_get_connection_in()); 1334 if (p == NULL) { 1335 if (gethostname(myname, sizeof(myname)) == -1) { 1336 verbose("userauth_hostbased: gethostname: %s", 1337 strerror(errno)); 1338 } else 1339 p = xstrdup(myname); 1340 } 1341 if (p == NULL) { 1342 error("userauth_hostbased: cannot get local ipaddr/name"); 1343 key_free(private); 1344 xfree(blob); 1345 return 0; 1346 } 1347 len = strlen(p) + 2; 1348 xasprintf(&chost, "%s.", p); 1349 debug2("userauth_hostbased: chost %s", chost); 1350 xfree(p); 1351 1352 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1353 authctxt->service; 1354 pkalg = xstrdup(key_ssh_name(private)); 1355 buffer_init(&b); 1356 /* construct data */ 1357 buffer_put_string(&b, session_id2, session_id2_len); 1358 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1359 buffer_put_cstring(&b, authctxt->server_user); 1360 buffer_put_cstring(&b, service); 1361 buffer_put_cstring(&b, authctxt->method->name); 1362 buffer_put_cstring(&b, pkalg); 1363 buffer_put_string(&b, blob, blen); 1364 buffer_put_cstring(&b, chost); 1365 buffer_put_cstring(&b, authctxt->local_user); 1366 #ifdef DEBUG_PK 1367 buffer_dump(&b); 1368 #endif 1369 if (sensitive->external_keysign) 1370 ok = ssh_keysign(private, &signature, &slen, 1371 buffer_ptr(&b), buffer_len(&b)); 1372 else 1373 ok = key_sign(private, &signature, &slen, 1374 buffer_ptr(&b), buffer_len(&b)); 1375 key_free(private); 1376 buffer_free(&b); 1377 if (ok != 0) { 1378 error("key_sign failed"); 1379 xfree(chost); 1380 xfree(pkalg); 1381 xfree(blob); 1382 return 0; 1383 } 1384 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1385 packet_put_cstring(authctxt->server_user); 1386 packet_put_cstring(authctxt->service); 1387 packet_put_cstring(authctxt->method->name); 1388 packet_put_cstring(pkalg); 1389 packet_put_string(blob, blen); 1390 packet_put_cstring(chost); 1391 packet_put_cstring(authctxt->local_user); 1392 packet_put_string(signature, slen); 1393 memset(signature, 's', slen); 1394 xfree(signature); 1395 xfree(chost); 1396 xfree(pkalg); 1397 xfree(blob); 1398 1399 packet_send(); 1400 return 1; 1401 } 1402 1403 /* find auth method */ 1404 1405 /* 1406 * given auth method name, if configurable options permit this method fill 1407 * in auth_ident field and return true, otherwise return false. 1408 */ 1409 static int 1410 authmethod_is_enabled(Authmethod *method) 1411 { 1412 if (method == NULL) 1413 return 0; 1414 /* return false if options indicate this method is disabled */ 1415 if (method->enabled == NULL || *method->enabled == 0) 1416 return 0; 1417 /* return false if batch mode is enabled but method needs interactive mode */ 1418 if (method->batch_flag != NULL && *method->batch_flag != 0) 1419 return 0; 1420 return 1; 1421 } 1422 1423 static Authmethod * 1424 authmethod_lookup(const char *name) 1425 { 1426 Authmethod *method = NULL; 1427 if (name != NULL) 1428 for (method = authmethods; method->name != NULL; method++) 1429 if (strcmp(name, method->name) == 0) 1430 return method; 1431 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1432 return NULL; 1433 } 1434 1435 /* XXX internal state */ 1436 static Authmethod *current = NULL; 1437 static char *supported = NULL; 1438 static char *preferred = NULL; 1439 1440 /* 1441 * Given the authentication method list sent by the server, return the 1442 * next method we should try. If the server initially sends a nil list, 1443 * use a built-in default list. 1444 */ 1445 static Authmethod * 1446 authmethod_get(char *authlist) 1447 { 1448 char *name = NULL; 1449 u_int next; 1450 1451 /* Use a suitable default if we're passed a nil list. */ 1452 if (authlist == NULL || strlen(authlist) == 0) 1453 authlist = options.preferred_authentications; 1454 1455 if (supported == NULL || strcmp(authlist, supported) != 0) { 1456 debug3("start over, passed a different list %s", authlist); 1457 if (supported != NULL) 1458 xfree(supported); 1459 supported = xstrdup(authlist); 1460 preferred = options.preferred_authentications; 1461 debug3("preferred %s", preferred); 1462 current = NULL; 1463 } else if (current != NULL && authmethod_is_enabled(current)) 1464 return current; 1465 1466 for (;;) { 1467 if ((name = match_list(preferred, supported, &next)) == NULL) { 1468 debug("No more authentication methods to try."); 1469 current = NULL; 1470 return NULL; 1471 } 1472 preferred += next; 1473 debug3("authmethod_lookup %s", name); 1474 debug3("remaining preferred: %s", preferred); 1475 if ((current = authmethod_lookup(name)) != NULL && 1476 authmethod_is_enabled(current)) { 1477 debug3("authmethod_is_enabled %s", name); 1478 debug("Next authentication method: %s", name); 1479 return current; 1480 } 1481 } 1482 } 1483 1484 static char * 1485 authmethods_get(void) 1486 { 1487 Authmethod *method = NULL; 1488 Buffer b; 1489 char *list; 1490 1491 buffer_init(&b); 1492 for (method = authmethods; method->name != NULL; method++) { 1493 if (authmethod_is_enabled(method)) { 1494 if (buffer_len(&b) > 0) 1495 buffer_append(&b, ",", 1); 1496 buffer_append(&b, method->name, strlen(method->name)); 1497 } 1498 } 1499 buffer_append(&b, "\0", 1); 1500 list = xstrdup(buffer_ptr(&b)); 1501 buffer_free(&b); 1502 return list; 1503 } 1504