1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "readconf.h" 59 #include "misc.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "hostfile.h" 67 68 #ifdef GSSAPI 69 #include "ssh-gss.h" 70 #endif 71 72 /* import */ 73 extern char *client_version_string; 74 extern char *server_version_string; 75 extern Options options; 76 77 /* 78 * SSH2 key exchange 79 */ 80 81 u_char *session_id2 = NULL; 82 u_int session_id2_len = 0; 83 84 char *xxx_host; 85 struct sockaddr *xxx_hostaddr; 86 87 Kex *xxx_kex = NULL; 88 89 static int 90 verify_host_key_callback(Key *hostkey) 91 { 92 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 93 fatal("Host key verification failed."); 94 return 0; 95 } 96 97 static char * 98 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 99 { 100 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 101 size_t maxlen; 102 struct hostkeys *hostkeys; 103 int ktype; 104 u_int i; 105 106 /* Find all hostkeys for this hostname */ 107 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 108 hostkeys = init_hostkeys(); 109 for (i = 0; i < options.num_user_hostfiles; i++) 110 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 111 for (i = 0; i < options.num_system_hostfiles; i++) 112 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 113 114 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 115 maxlen = strlen(avail) + 1; 116 first = xmalloc(maxlen); 117 last = xmalloc(maxlen); 118 *first = *last = '\0'; 119 120 #define ALG_APPEND(to, from) \ 121 do { \ 122 if (*to != '\0') \ 123 strlcat(to, ",", maxlen); \ 124 strlcat(to, from, maxlen); \ 125 } while (0) 126 127 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 128 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 129 fatal("%s: unknown alg %s", __func__, alg); 130 if (lookup_key_in_hostkeys_by_type(hostkeys, 131 key_type_plain(ktype), NULL)) 132 ALG_APPEND(first, alg); 133 else 134 ALG_APPEND(last, alg); 135 } 136 #undef ALG_APPEND 137 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 138 if (*first != '\0') 139 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 140 141 free(first); 142 free(last); 143 free(hostname); 144 free(oavail); 145 free_hostkeys(hostkeys); 146 147 return ret; 148 } 149 150 void 151 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 152 { 153 Kex *kex; 154 155 xxx_host = host; 156 xxx_hostaddr = hostaddr; 157 158 if (options.ciphers == (char *)-1) { 159 logit("No valid ciphers for protocol version 2 given, using defaults."); 160 options.ciphers = NULL; 161 } 162 if (options.ciphers != NULL) { 163 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 164 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 165 } 166 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 167 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 168 myproposal[PROPOSAL_ENC_ALGS_STOC] = 169 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 170 if (options.compression) { 171 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 172 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 173 } else { 174 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 175 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 176 } 177 if (options.macs != NULL) { 178 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 179 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 180 } 181 if (options.hostkeyalgorithms != NULL) 182 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 183 compat_pkalg_proposal(options.hostkeyalgorithms); 184 else { 185 /* Prefer algorithms that we already have keys for */ 186 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 187 compat_pkalg_proposal( 188 order_hostkeyalgs(host, hostaddr, port)); 189 } 190 if (options.kex_algorithms != NULL) 191 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 192 193 if (options.rekey_limit || options.rekey_interval) 194 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 195 (time_t)options.rekey_interval); 196 197 /* start key exchange */ 198 kex = kex_setup(myproposal); 199 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 200 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 201 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 202 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 203 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 204 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 205 kex->client_version_string=client_version_string; 206 kex->server_version_string=server_version_string; 207 kex->verify_host_key=&verify_host_key_callback; 208 209 xxx_kex = kex; 210 211 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 212 213 if (options.use_roaming && !kex->roaming) { 214 debug("Roaming not allowed by server"); 215 options.use_roaming = 0; 216 } 217 218 session_id2 = kex->session_id; 219 session_id2_len = kex->session_id_len; 220 221 #ifdef DEBUG_KEXDH 222 /* send 1st encrypted/maced/compressed message */ 223 packet_start(SSH2_MSG_IGNORE); 224 packet_put_cstring("markus"); 225 packet_send(); 226 packet_write_wait(); 227 #endif 228 } 229 230 /* 231 * Authenticate user 232 */ 233 234 typedef struct Authctxt Authctxt; 235 typedef struct Authmethod Authmethod; 236 typedef struct identity Identity; 237 typedef struct idlist Idlist; 238 239 struct identity { 240 TAILQ_ENTRY(identity) next; 241 AuthenticationConnection *ac; /* set if agent supports key */ 242 Key *key; /* public/private key */ 243 char *filename; /* comment for agent-only keys */ 244 int tried; 245 int isprivate; /* key points to the private key */ 246 int userprovided; 247 }; 248 TAILQ_HEAD(idlist, identity); 249 250 struct Authctxt { 251 const char *server_user; 252 const char *local_user; 253 const char *host; 254 const char *service; 255 Authmethod *method; 256 sig_atomic_t success; 257 char *authlist; 258 /* pubkey */ 259 Idlist keys; 260 AuthenticationConnection *agent; 261 /* hostbased */ 262 Sensitive *sensitive; 263 /* kbd-interactive */ 264 int info_req_seen; 265 /* generic */ 266 void *methoddata; 267 }; 268 struct Authmethod { 269 char *name; /* string to compare against server's list */ 270 int (*userauth)(Authctxt *authctxt); 271 void (*cleanup)(Authctxt *authctxt); 272 int *enabled; /* flag in option struct that enables method */ 273 int *batch_flag; /* flag in option struct that disables method */ 274 }; 275 276 void input_userauth_success(int, u_int32_t, void *); 277 void input_userauth_success_unexpected(int, u_int32_t, void *); 278 void input_userauth_failure(int, u_int32_t, void *); 279 void input_userauth_banner(int, u_int32_t, void *); 280 void input_userauth_error(int, u_int32_t, void *); 281 void input_userauth_info_req(int, u_int32_t, void *); 282 void input_userauth_pk_ok(int, u_int32_t, void *); 283 void input_userauth_passwd_changereq(int, u_int32_t, void *); 284 285 int userauth_none(Authctxt *); 286 int userauth_pubkey(Authctxt *); 287 int userauth_passwd(Authctxt *); 288 int userauth_kbdint(Authctxt *); 289 int userauth_hostbased(Authctxt *); 290 291 #ifdef GSSAPI 292 int userauth_gssapi(Authctxt *authctxt); 293 void input_gssapi_response(int type, u_int32_t, void *); 294 void input_gssapi_token(int type, u_int32_t, void *); 295 void input_gssapi_hash(int type, u_int32_t, void *); 296 void input_gssapi_error(int, u_int32_t, void *); 297 void input_gssapi_errtok(int, u_int32_t, void *); 298 #endif 299 300 void userauth(Authctxt *, char *); 301 302 static int sign_and_send_pubkey(Authctxt *, Identity *); 303 static void pubkey_prepare(Authctxt *); 304 static void pubkey_cleanup(Authctxt *); 305 static Key *load_identity_file(char *, int); 306 307 static Authmethod *authmethod_get(char *authlist); 308 static Authmethod *authmethod_lookup(const char *name); 309 static char *authmethods_get(void); 310 311 Authmethod authmethods[] = { 312 #ifdef GSSAPI 313 {"gssapi-with-mic", 314 userauth_gssapi, 315 NULL, 316 &options.gss_authentication, 317 NULL}, 318 #endif 319 {"hostbased", 320 userauth_hostbased, 321 NULL, 322 &options.hostbased_authentication, 323 NULL}, 324 {"publickey", 325 userauth_pubkey, 326 NULL, 327 &options.pubkey_authentication, 328 NULL}, 329 {"keyboard-interactive", 330 userauth_kbdint, 331 NULL, 332 &options.kbd_interactive_authentication, 333 &options.batch_mode}, 334 {"password", 335 userauth_passwd, 336 NULL, 337 &options.password_authentication, 338 &options.batch_mode}, 339 {"none", 340 userauth_none, 341 NULL, 342 NULL, 343 NULL}, 344 {NULL, NULL, NULL, NULL, NULL} 345 }; 346 347 void 348 ssh_userauth2(const char *local_user, const char *server_user, char *host, 349 Sensitive *sensitive) 350 { 351 Authctxt authctxt; 352 int type; 353 354 if (options.challenge_response_authentication) 355 options.kbd_interactive_authentication = 1; 356 357 packet_start(SSH2_MSG_SERVICE_REQUEST); 358 packet_put_cstring("ssh-userauth"); 359 packet_send(); 360 debug("SSH2_MSG_SERVICE_REQUEST sent"); 361 packet_write_wait(); 362 type = packet_read(); 363 if (type != SSH2_MSG_SERVICE_ACCEPT) 364 fatal("Server denied authentication request: %d", type); 365 if (packet_remaining() > 0) { 366 char *reply = packet_get_string(NULL); 367 debug2("service_accept: %s", reply); 368 free(reply); 369 } else { 370 debug2("buggy server: service_accept w/o service"); 371 } 372 packet_check_eom(); 373 debug("SSH2_MSG_SERVICE_ACCEPT received"); 374 375 if (options.preferred_authentications == NULL) 376 options.preferred_authentications = authmethods_get(); 377 378 /* setup authentication context */ 379 memset(&authctxt, 0, sizeof(authctxt)); 380 pubkey_prepare(&authctxt); 381 authctxt.server_user = server_user; 382 authctxt.local_user = local_user; 383 authctxt.host = host; 384 authctxt.service = "ssh-connection"; /* service name */ 385 authctxt.success = 0; 386 authctxt.method = authmethod_lookup("none"); 387 authctxt.authlist = NULL; 388 authctxt.methoddata = NULL; 389 authctxt.sensitive = sensitive; 390 authctxt.info_req_seen = 0; 391 if (authctxt.method == NULL) 392 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 393 394 /* initial userauth request */ 395 userauth_none(&authctxt); 396 397 dispatch_init(&input_userauth_error); 398 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 399 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 400 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 401 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 402 403 pubkey_cleanup(&authctxt); 404 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 405 406 debug("Authentication succeeded (%s).", authctxt.method->name); 407 } 408 409 void 410 userauth(Authctxt *authctxt, char *authlist) 411 { 412 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 413 authctxt->method->cleanup(authctxt); 414 415 free(authctxt->methoddata); 416 authctxt->methoddata = NULL; 417 if (authlist == NULL) { 418 authlist = authctxt->authlist; 419 } else { 420 free(authctxt->authlist); 421 authctxt->authlist = authlist; 422 } 423 for (;;) { 424 Authmethod *method = authmethod_get(authlist); 425 if (method == NULL) 426 fatal("Permission denied (%s).", authlist); 427 authctxt->method = method; 428 429 /* reset the per method handler */ 430 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 431 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 432 433 /* and try new method */ 434 if (method->userauth(authctxt) != 0) { 435 debug2("we sent a %s packet, wait for reply", method->name); 436 break; 437 } else { 438 debug2("we did not send a packet, disable method"); 439 method->enabled = NULL; 440 } 441 } 442 } 443 444 /* ARGSUSED */ 445 void 446 input_userauth_error(int type, u_int32_t seq, void *ctxt) 447 { 448 fatal("input_userauth_error: bad message during authentication: " 449 "type %d", type); 450 } 451 452 /* ARGSUSED */ 453 void 454 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 455 { 456 char *msg, *raw, *lang; 457 u_int len; 458 459 debug3("input_userauth_banner"); 460 raw = packet_get_string(&len); 461 lang = packet_get_string(NULL); 462 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 463 if (len > 65536) 464 len = 65536; 465 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 466 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 467 fprintf(stderr, "%s", msg); 468 free(msg); 469 } 470 free(raw); 471 free(lang); 472 } 473 474 /* ARGSUSED */ 475 void 476 input_userauth_success(int type, u_int32_t seq, void *ctxt) 477 { 478 Authctxt *authctxt = ctxt; 479 480 if (authctxt == NULL) 481 fatal("input_userauth_success: no authentication context"); 482 free(authctxt->authlist); 483 authctxt->authlist = NULL; 484 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 485 authctxt->method->cleanup(authctxt); 486 free(authctxt->methoddata); 487 authctxt->methoddata = NULL; 488 authctxt->success = 1; /* break out */ 489 } 490 491 void 492 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 493 { 494 Authctxt *authctxt = ctxt; 495 496 if (authctxt == NULL) 497 fatal("%s: no authentication context", __func__); 498 499 fatal("Unexpected authentication success during %s.", 500 authctxt->method->name); 501 } 502 503 /* ARGSUSED */ 504 void 505 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 506 { 507 Authctxt *authctxt = ctxt; 508 char *authlist = NULL; 509 int partial; 510 511 if (authctxt == NULL) 512 fatal("input_userauth_failure: no authentication context"); 513 514 authlist = packet_get_string(NULL); 515 partial = packet_get_char(); 516 packet_check_eom(); 517 518 if (partial != 0) { 519 logit("Authenticated with partial success."); 520 /* reset state */ 521 pubkey_cleanup(authctxt); 522 pubkey_prepare(authctxt); 523 } 524 debug("Authentications that can continue: %s", authlist); 525 526 userauth(authctxt, authlist); 527 } 528 529 /* ARGSUSED */ 530 void 531 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 532 { 533 Authctxt *authctxt = ctxt; 534 Key *key = NULL; 535 Identity *id = NULL; 536 Buffer b; 537 int pktype, sent = 0; 538 u_int alen, blen; 539 char *pkalg, *fp; 540 u_char *pkblob; 541 542 if (authctxt == NULL) 543 fatal("input_userauth_pk_ok: no authentication context"); 544 if (datafellows & SSH_BUG_PKOK) { 545 /* this is similar to SSH_BUG_PKAUTH */ 546 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 547 pkblob = packet_get_string(&blen); 548 buffer_init(&b); 549 buffer_append(&b, pkblob, blen); 550 pkalg = buffer_get_string(&b, &alen); 551 buffer_free(&b); 552 } else { 553 pkalg = packet_get_string(&alen); 554 pkblob = packet_get_string(&blen); 555 } 556 packet_check_eom(); 557 558 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 559 560 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 561 debug("unknown pkalg %s", pkalg); 562 goto done; 563 } 564 if ((key = key_from_blob(pkblob, blen)) == NULL) { 565 debug("no key from blob. pkalg %s", pkalg); 566 goto done; 567 } 568 if (key->type != pktype) { 569 error("input_userauth_pk_ok: type mismatch " 570 "for decoded key (received %d, expected %d)", 571 key->type, pktype); 572 goto done; 573 } 574 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 575 debug2("input_userauth_pk_ok: fp %s", fp); 576 free(fp); 577 578 /* 579 * search keys in the reverse order, because last candidate has been 580 * moved to the end of the queue. this also avoids confusion by 581 * duplicate keys 582 */ 583 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 584 if (key_equal(key, id->key)) { 585 sent = sign_and_send_pubkey(authctxt, id); 586 break; 587 } 588 } 589 done: 590 if (key != NULL) 591 key_free(key); 592 free(pkalg); 593 free(pkblob); 594 595 /* try another method if we did not send a packet */ 596 if (sent == 0) 597 userauth(authctxt, NULL); 598 } 599 600 #ifdef GSSAPI 601 int 602 userauth_gssapi(Authctxt *authctxt) 603 { 604 Gssctxt *gssctxt = NULL; 605 static gss_OID_set gss_supported = NULL; 606 static u_int mech = 0; 607 OM_uint32 min; 608 int ok = 0; 609 610 /* Try one GSSAPI method at a time, rather than sending them all at 611 * once. */ 612 613 if (gss_supported == NULL) 614 gss_indicate_mechs(&min, &gss_supported); 615 616 /* Check to see if the mechanism is usable before we offer it */ 617 while (mech < gss_supported->count && !ok) { 618 /* My DER encoding requires length<128 */ 619 if (gss_supported->elements[mech].length < 128 && 620 ssh_gssapi_check_mechanism(&gssctxt, 621 &gss_supported->elements[mech], authctxt->host)) { 622 ok = 1; /* Mechanism works */ 623 } else { 624 mech++; 625 } 626 } 627 628 if (!ok) 629 return 0; 630 631 authctxt->methoddata=(void *)gssctxt; 632 633 packet_start(SSH2_MSG_USERAUTH_REQUEST); 634 packet_put_cstring(authctxt->server_user); 635 packet_put_cstring(authctxt->service); 636 packet_put_cstring(authctxt->method->name); 637 638 packet_put_int(1); 639 640 packet_put_int((gss_supported->elements[mech].length) + 2); 641 packet_put_char(SSH_GSS_OIDTYPE); 642 packet_put_char(gss_supported->elements[mech].length); 643 packet_put_raw(gss_supported->elements[mech].elements, 644 gss_supported->elements[mech].length); 645 646 packet_send(); 647 648 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 649 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 650 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 651 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 652 653 mech++; /* Move along to next candidate */ 654 655 return 1; 656 } 657 658 static OM_uint32 659 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 660 { 661 Authctxt *authctxt = ctxt; 662 Gssctxt *gssctxt = authctxt->methoddata; 663 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 664 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 665 gss_buffer_desc gssbuf; 666 OM_uint32 status, ms, flags; 667 Buffer b; 668 669 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 670 recv_tok, &send_tok, &flags); 671 672 if (send_tok.length > 0) { 673 if (GSS_ERROR(status)) 674 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 675 else 676 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 677 678 packet_put_string(send_tok.value, send_tok.length); 679 packet_send(); 680 gss_release_buffer(&ms, &send_tok); 681 } 682 683 if (status == GSS_S_COMPLETE) { 684 /* send either complete or MIC, depending on mechanism */ 685 if (!(flags & GSS_C_INTEG_FLAG)) { 686 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 687 packet_send(); 688 } else { 689 ssh_gssapi_buildmic(&b, authctxt->server_user, 690 authctxt->service, "gssapi-with-mic"); 691 692 gssbuf.value = buffer_ptr(&b); 693 gssbuf.length = buffer_len(&b); 694 695 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 696 697 if (!GSS_ERROR(status)) { 698 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 699 packet_put_string(mic.value, mic.length); 700 701 packet_send(); 702 } 703 704 buffer_free(&b); 705 gss_release_buffer(&ms, &mic); 706 } 707 } 708 709 return status; 710 } 711 712 /* ARGSUSED */ 713 void 714 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 715 { 716 Authctxt *authctxt = ctxt; 717 Gssctxt *gssctxt; 718 int oidlen; 719 char *oidv; 720 721 if (authctxt == NULL) 722 fatal("input_gssapi_response: no authentication context"); 723 gssctxt = authctxt->methoddata; 724 725 /* Setup our OID */ 726 oidv = packet_get_string(&oidlen); 727 728 if (oidlen <= 2 || 729 oidv[0] != SSH_GSS_OIDTYPE || 730 oidv[1] != oidlen - 2) { 731 free(oidv); 732 debug("Badly encoded mechanism OID received"); 733 userauth(authctxt, NULL); 734 return; 735 } 736 737 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 738 fatal("Server returned different OID than expected"); 739 740 packet_check_eom(); 741 742 free(oidv); 743 744 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 745 /* Start again with next method on list */ 746 debug("Trying to start again"); 747 userauth(authctxt, NULL); 748 return; 749 } 750 } 751 752 /* ARGSUSED */ 753 void 754 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 755 { 756 Authctxt *authctxt = ctxt; 757 gss_buffer_desc recv_tok; 758 OM_uint32 status; 759 u_int slen; 760 761 if (authctxt == NULL) 762 fatal("input_gssapi_response: no authentication context"); 763 764 recv_tok.value = packet_get_string(&slen); 765 recv_tok.length = slen; /* safe typecast */ 766 767 packet_check_eom(); 768 769 status = process_gssapi_token(ctxt, &recv_tok); 770 771 free(recv_tok.value); 772 773 if (GSS_ERROR(status)) { 774 /* Start again with the next method in the list */ 775 userauth(authctxt, NULL); 776 return; 777 } 778 } 779 780 /* ARGSUSED */ 781 void 782 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 783 { 784 Authctxt *authctxt = ctxt; 785 Gssctxt *gssctxt; 786 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 787 gss_buffer_desc recv_tok; 788 OM_uint32 ms; 789 u_int len; 790 791 if (authctxt == NULL) 792 fatal("input_gssapi_response: no authentication context"); 793 gssctxt = authctxt->methoddata; 794 795 recv_tok.value = packet_get_string(&len); 796 recv_tok.length = len; 797 798 packet_check_eom(); 799 800 /* Stick it into GSSAPI and see what it says */ 801 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 802 &recv_tok, &send_tok, NULL); 803 804 free(recv_tok.value); 805 gss_release_buffer(&ms, &send_tok); 806 807 /* Server will be returning a failed packet after this one */ 808 } 809 810 /* ARGSUSED */ 811 void 812 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 813 { 814 char *msg; 815 char *lang; 816 817 /* maj */(void)packet_get_int(); 818 /* min */(void)packet_get_int(); 819 msg=packet_get_string(NULL); 820 lang=packet_get_string(NULL); 821 822 packet_check_eom(); 823 824 debug("Server GSSAPI Error:\n%s", msg); 825 free(msg); 826 free(lang); 827 } 828 #endif /* GSSAPI */ 829 830 int 831 userauth_none(Authctxt *authctxt) 832 { 833 /* initial userauth request */ 834 packet_start(SSH2_MSG_USERAUTH_REQUEST); 835 packet_put_cstring(authctxt->server_user); 836 packet_put_cstring(authctxt->service); 837 packet_put_cstring(authctxt->method->name); 838 packet_send(); 839 return 1; 840 } 841 842 int 843 userauth_passwd(Authctxt *authctxt) 844 { 845 static int attempt = 0; 846 char prompt[150]; 847 char *password; 848 const char *host = options.host_key_alias ? options.host_key_alias : 849 authctxt->host; 850 851 if (attempt++ >= options.number_of_password_prompts) 852 return 0; 853 854 if (attempt != 1) 855 error("Permission denied, please try again."); 856 857 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 858 authctxt->server_user, host); 859 password = read_passphrase(prompt, 0); 860 packet_start(SSH2_MSG_USERAUTH_REQUEST); 861 packet_put_cstring(authctxt->server_user); 862 packet_put_cstring(authctxt->service); 863 packet_put_cstring(authctxt->method->name); 864 packet_put_char(0); 865 packet_put_cstring(password); 866 explicit_bzero(password, strlen(password)); 867 free(password); 868 packet_add_padding(64); 869 packet_send(); 870 871 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 872 &input_userauth_passwd_changereq); 873 874 return 1; 875 } 876 877 /* 878 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 879 */ 880 /* ARGSUSED */ 881 void 882 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 883 { 884 Authctxt *authctxt = ctxt; 885 char *info, *lang, *password = NULL, *retype = NULL; 886 char prompt[150]; 887 const char *host = options.host_key_alias ? options.host_key_alias : 888 authctxt->host; 889 890 debug2("input_userauth_passwd_changereq"); 891 892 if (authctxt == NULL) 893 fatal("input_userauth_passwd_changereq: " 894 "no authentication context"); 895 896 info = packet_get_string(NULL); 897 lang = packet_get_string(NULL); 898 if (strlen(info) > 0) 899 logit("%s", info); 900 free(info); 901 free(lang); 902 packet_start(SSH2_MSG_USERAUTH_REQUEST); 903 packet_put_cstring(authctxt->server_user); 904 packet_put_cstring(authctxt->service); 905 packet_put_cstring(authctxt->method->name); 906 packet_put_char(1); /* additional info */ 907 snprintf(prompt, sizeof(prompt), 908 "Enter %.30s@%.128s's old password: ", 909 authctxt->server_user, host); 910 password = read_passphrase(prompt, 0); 911 packet_put_cstring(password); 912 explicit_bzero(password, strlen(password)); 913 free(password); 914 password = NULL; 915 while (password == NULL) { 916 snprintf(prompt, sizeof(prompt), 917 "Enter %.30s@%.128s's new password: ", 918 authctxt->server_user, host); 919 password = read_passphrase(prompt, RP_ALLOW_EOF); 920 if (password == NULL) { 921 /* bail out */ 922 return; 923 } 924 snprintf(prompt, sizeof(prompt), 925 "Retype %.30s@%.128s's new password: ", 926 authctxt->server_user, host); 927 retype = read_passphrase(prompt, 0); 928 if (strcmp(password, retype) != 0) { 929 explicit_bzero(password, strlen(password)); 930 free(password); 931 logit("Mismatch; try again, EOF to quit."); 932 password = NULL; 933 } 934 explicit_bzero(retype, strlen(retype)); 935 free(retype); 936 } 937 packet_put_cstring(password); 938 explicit_bzero(password, strlen(password)); 939 free(password); 940 packet_add_padding(64); 941 packet_send(); 942 943 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 944 &input_userauth_passwd_changereq); 945 } 946 947 static int 948 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 949 u_char *data, u_int datalen) 950 { 951 Key *prv; 952 int ret; 953 954 /* the agent supports this key */ 955 if (id->ac) 956 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 957 data, datalen)); 958 /* 959 * we have already loaded the private key or 960 * the private key is stored in external hardware 961 */ 962 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 963 return (key_sign(id->key, sigp, lenp, data, datalen)); 964 /* load the private key from the file */ 965 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 966 return (-1); 967 ret = key_sign(prv, sigp, lenp, data, datalen); 968 key_free(prv); 969 return (ret); 970 } 971 972 static int 973 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 974 { 975 Buffer b; 976 u_char *blob, *signature; 977 u_int bloblen, slen; 978 u_int skip = 0; 979 int ret = -1; 980 int have_sig = 1; 981 char *fp; 982 983 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 984 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 985 free(fp); 986 987 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 988 /* we cannot handle this key */ 989 debug3("sign_and_send_pubkey: cannot handle key"); 990 return 0; 991 } 992 /* data to be signed */ 993 buffer_init(&b); 994 if (datafellows & SSH_OLD_SESSIONID) { 995 buffer_append(&b, session_id2, session_id2_len); 996 skip = session_id2_len; 997 } else { 998 buffer_put_string(&b, session_id2, session_id2_len); 999 skip = buffer_len(&b); 1000 } 1001 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1002 buffer_put_cstring(&b, authctxt->server_user); 1003 buffer_put_cstring(&b, 1004 datafellows & SSH_BUG_PKSERVICE ? 1005 "ssh-userauth" : 1006 authctxt->service); 1007 if (datafellows & SSH_BUG_PKAUTH) { 1008 buffer_put_char(&b, have_sig); 1009 } else { 1010 buffer_put_cstring(&b, authctxt->method->name); 1011 buffer_put_char(&b, have_sig); 1012 buffer_put_cstring(&b, key_ssh_name(id->key)); 1013 } 1014 buffer_put_string(&b, blob, bloblen); 1015 1016 /* generate signature */ 1017 ret = identity_sign(id, &signature, &slen, 1018 buffer_ptr(&b), buffer_len(&b)); 1019 if (ret == -1) { 1020 free(blob); 1021 buffer_free(&b); 1022 return 0; 1023 } 1024 #ifdef DEBUG_PK 1025 buffer_dump(&b); 1026 #endif 1027 if (datafellows & SSH_BUG_PKSERVICE) { 1028 buffer_clear(&b); 1029 buffer_append(&b, session_id2, session_id2_len); 1030 skip = session_id2_len; 1031 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1032 buffer_put_cstring(&b, authctxt->server_user); 1033 buffer_put_cstring(&b, authctxt->service); 1034 buffer_put_cstring(&b, authctxt->method->name); 1035 buffer_put_char(&b, have_sig); 1036 if (!(datafellows & SSH_BUG_PKAUTH)) 1037 buffer_put_cstring(&b, key_ssh_name(id->key)); 1038 buffer_put_string(&b, blob, bloblen); 1039 } 1040 free(blob); 1041 1042 /* append signature */ 1043 buffer_put_string(&b, signature, slen); 1044 free(signature); 1045 1046 /* skip session id and packet type */ 1047 if (buffer_len(&b) < skip + 1) 1048 fatal("userauth_pubkey: internal error"); 1049 buffer_consume(&b, skip + 1); 1050 1051 /* put remaining data from buffer into packet */ 1052 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1053 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1054 buffer_free(&b); 1055 packet_send(); 1056 1057 return 1; 1058 } 1059 1060 static int 1061 send_pubkey_test(Authctxt *authctxt, Identity *id) 1062 { 1063 u_char *blob; 1064 u_int bloblen, have_sig = 0; 1065 1066 debug3("send_pubkey_test"); 1067 1068 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1069 /* we cannot handle this key */ 1070 debug3("send_pubkey_test: cannot handle key"); 1071 return 0; 1072 } 1073 /* register callback for USERAUTH_PK_OK message */ 1074 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1075 1076 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1077 packet_put_cstring(authctxt->server_user); 1078 packet_put_cstring(authctxt->service); 1079 packet_put_cstring(authctxt->method->name); 1080 packet_put_char(have_sig); 1081 if (!(datafellows & SSH_BUG_PKAUTH)) 1082 packet_put_cstring(key_ssh_name(id->key)); 1083 packet_put_string(blob, bloblen); 1084 free(blob); 1085 packet_send(); 1086 return 1; 1087 } 1088 1089 static Key * 1090 load_identity_file(char *filename, int userprovided) 1091 { 1092 Key *private; 1093 char prompt[300], *passphrase; 1094 int perm_ok = 0, quit, i; 1095 struct stat st; 1096 1097 if (stat(filename, &st) < 0) { 1098 (userprovided ? logit : debug3)("no such identity: %s: %s", 1099 filename, strerror(errno)); 1100 return NULL; 1101 } 1102 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1103 if (!perm_ok) { 1104 if (private != NULL) 1105 key_free(private); 1106 return NULL; 1107 } 1108 if (private == NULL) { 1109 if (options.batch_mode) 1110 return NULL; 1111 snprintf(prompt, sizeof prompt, 1112 "Enter passphrase for key '%.100s': ", filename); 1113 for (i = 0; i < options.number_of_password_prompts; i++) { 1114 passphrase = read_passphrase(prompt, 0); 1115 if (strcmp(passphrase, "") != 0) { 1116 private = key_load_private_type(KEY_UNSPEC, 1117 filename, passphrase, NULL, NULL); 1118 quit = 0; 1119 } else { 1120 debug2("no passphrase given, try next key"); 1121 quit = 1; 1122 } 1123 explicit_bzero(passphrase, strlen(passphrase)); 1124 free(passphrase); 1125 if (private != NULL || quit) 1126 break; 1127 debug2("bad passphrase given, try again..."); 1128 } 1129 } 1130 return private; 1131 } 1132 1133 /* 1134 * try keys in the following order: 1135 * 1. agent keys that are found in the config file 1136 * 2. other agent keys 1137 * 3. keys that are only listed in the config file 1138 */ 1139 static void 1140 pubkey_prepare(Authctxt *authctxt) 1141 { 1142 Identity *id, *id2, *tmp; 1143 Idlist agent, files, *preferred; 1144 Key *key; 1145 AuthenticationConnection *ac; 1146 char *comment; 1147 int i, found; 1148 1149 TAILQ_INIT(&agent); /* keys from the agent */ 1150 TAILQ_INIT(&files); /* keys from the config file */ 1151 preferred = &authctxt->keys; 1152 TAILQ_INIT(preferred); /* preferred order of keys */ 1153 1154 /* list of keys stored in the filesystem and PKCS#11 */ 1155 for (i = 0; i < options.num_identity_files; i++) { 1156 key = options.identity_keys[i]; 1157 if (key && key->type == KEY_RSA1) 1158 continue; 1159 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1160 continue; 1161 options.identity_keys[i] = NULL; 1162 id = xcalloc(1, sizeof(*id)); 1163 id->key = key; 1164 id->filename = xstrdup(options.identity_files[i]); 1165 id->userprovided = options.identity_file_userprovided[i]; 1166 TAILQ_INSERT_TAIL(&files, id, next); 1167 } 1168 /* Prefer PKCS11 keys that are explicitly listed */ 1169 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1170 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1171 continue; 1172 found = 0; 1173 TAILQ_FOREACH(id2, &files, next) { 1174 if (id2->key == NULL || 1175 (id2->key->flags & KEY_FLAG_EXT) != 0) 1176 continue; 1177 if (key_equal(id->key, id2->key)) { 1178 TAILQ_REMOVE(&files, id, next); 1179 TAILQ_INSERT_TAIL(preferred, id, next); 1180 found = 1; 1181 break; 1182 } 1183 } 1184 /* If IdentitiesOnly set and key not found then don't use it */ 1185 if (!found && options.identities_only) { 1186 TAILQ_REMOVE(&files, id, next); 1187 explicit_bzero(id, sizeof(*id)); 1188 free(id); 1189 } 1190 } 1191 /* list of keys supported by the agent */ 1192 if ((ac = ssh_get_authentication_connection())) { 1193 for (key = ssh_get_first_identity(ac, &comment, 2); 1194 key != NULL; 1195 key = ssh_get_next_identity(ac, &comment, 2)) { 1196 found = 0; 1197 TAILQ_FOREACH(id, &files, next) { 1198 /* agent keys from the config file are preferred */ 1199 if (key_equal(key, id->key)) { 1200 key_free(key); 1201 free(comment); 1202 TAILQ_REMOVE(&files, id, next); 1203 TAILQ_INSERT_TAIL(preferred, id, next); 1204 id->ac = ac; 1205 found = 1; 1206 break; 1207 } 1208 } 1209 if (!found && !options.identities_only) { 1210 id = xcalloc(1, sizeof(*id)); 1211 id->key = key; 1212 id->filename = comment; 1213 id->ac = ac; 1214 TAILQ_INSERT_TAIL(&agent, id, next); 1215 } 1216 } 1217 /* append remaining agent keys */ 1218 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1219 TAILQ_REMOVE(&agent, id, next); 1220 TAILQ_INSERT_TAIL(preferred, id, next); 1221 } 1222 authctxt->agent = ac; 1223 } 1224 /* append remaining keys from the config file */ 1225 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1226 TAILQ_REMOVE(&files, id, next); 1227 TAILQ_INSERT_TAIL(preferred, id, next); 1228 } 1229 TAILQ_FOREACH(id, preferred, next) { 1230 debug2("key: %s (%p),%s", id->filename, id->key, 1231 id->userprovided ? " explicit" : ""); 1232 } 1233 } 1234 1235 static void 1236 pubkey_cleanup(Authctxt *authctxt) 1237 { 1238 Identity *id; 1239 1240 if (authctxt->agent != NULL) 1241 ssh_close_authentication_connection(authctxt->agent); 1242 for (id = TAILQ_FIRST(&authctxt->keys); id; 1243 id = TAILQ_FIRST(&authctxt->keys)) { 1244 TAILQ_REMOVE(&authctxt->keys, id, next); 1245 if (id->key) 1246 key_free(id->key); 1247 free(id->filename); 1248 free(id); 1249 } 1250 } 1251 1252 int 1253 userauth_pubkey(Authctxt *authctxt) 1254 { 1255 Identity *id; 1256 int sent = 0; 1257 1258 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1259 if (id->tried++) 1260 return (0); 1261 /* move key to the end of the queue */ 1262 TAILQ_REMOVE(&authctxt->keys, id, next); 1263 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1264 /* 1265 * send a test message if we have the public key. for 1266 * encrypted keys we cannot do this and have to load the 1267 * private key instead 1268 */ 1269 if (id->key != NULL) { 1270 if (key_type_plain(id->key->type) == KEY_RSA && 1271 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1272 debug("Skipped %s key %s for RSA/MD5 server", 1273 key_type(id->key), id->filename); 1274 } else if (id->key->type != KEY_RSA1) { 1275 debug("Offering %s public key: %s", 1276 key_type(id->key), id->filename); 1277 sent = send_pubkey_test(authctxt, id); 1278 } 1279 } else { 1280 debug("Trying private key: %s", id->filename); 1281 id->key = load_identity_file(id->filename, 1282 id->userprovided); 1283 if (id->key != NULL) { 1284 id->isprivate = 1; 1285 if (key_type_plain(id->key->type) == KEY_RSA && 1286 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1287 debug("Skipped %s key %s for RSA/MD5 " 1288 "server", key_type(id->key), 1289 id->filename); 1290 } else { 1291 sent = sign_and_send_pubkey( 1292 authctxt, id); 1293 } 1294 key_free(id->key); 1295 id->key = NULL; 1296 } 1297 } 1298 if (sent) 1299 return (sent); 1300 } 1301 return (0); 1302 } 1303 1304 /* 1305 * Send userauth request message specifying keyboard-interactive method. 1306 */ 1307 int 1308 userauth_kbdint(Authctxt *authctxt) 1309 { 1310 static int attempt = 0; 1311 1312 if (attempt++ >= options.number_of_password_prompts) 1313 return 0; 1314 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1315 if (attempt > 1 && !authctxt->info_req_seen) { 1316 debug3("userauth_kbdint: disable: no info_req_seen"); 1317 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1318 return 0; 1319 } 1320 1321 debug2("userauth_kbdint"); 1322 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1323 packet_put_cstring(authctxt->server_user); 1324 packet_put_cstring(authctxt->service); 1325 packet_put_cstring(authctxt->method->name); 1326 packet_put_cstring(""); /* lang */ 1327 packet_put_cstring(options.kbd_interactive_devices ? 1328 options.kbd_interactive_devices : ""); 1329 packet_send(); 1330 1331 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1332 return 1; 1333 } 1334 1335 /* 1336 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1337 */ 1338 void 1339 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1340 { 1341 Authctxt *authctxt = ctxt; 1342 char *name, *inst, *lang, *prompt, *response; 1343 u_int num_prompts, i; 1344 int echo = 0; 1345 1346 debug2("input_userauth_info_req"); 1347 1348 if (authctxt == NULL) 1349 fatal("input_userauth_info_req: no authentication context"); 1350 1351 authctxt->info_req_seen = 1; 1352 1353 name = packet_get_string(NULL); 1354 inst = packet_get_string(NULL); 1355 lang = packet_get_string(NULL); 1356 if (strlen(name) > 0) 1357 logit("%s", name); 1358 if (strlen(inst) > 0) 1359 logit("%s", inst); 1360 free(name); 1361 free(inst); 1362 free(lang); 1363 1364 num_prompts = packet_get_int(); 1365 /* 1366 * Begin to build info response packet based on prompts requested. 1367 * We commit to providing the correct number of responses, so if 1368 * further on we run into a problem that prevents this, we have to 1369 * be sure and clean this up and send a correct error response. 1370 */ 1371 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1372 packet_put_int(num_prompts); 1373 1374 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1375 for (i = 0; i < num_prompts; i++) { 1376 prompt = packet_get_string(NULL); 1377 echo = packet_get_char(); 1378 1379 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1380 1381 packet_put_cstring(response); 1382 explicit_bzero(response, strlen(response)); 1383 free(response); 1384 free(prompt); 1385 } 1386 packet_check_eom(); /* done with parsing incoming message. */ 1387 1388 packet_add_padding(64); 1389 packet_send(); 1390 } 1391 1392 static int 1393 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1394 u_char *data, u_int datalen) 1395 { 1396 Buffer b; 1397 struct stat st; 1398 pid_t pid; 1399 int to[2], from[2], status, version = 2; 1400 1401 debug2("ssh_keysign called"); 1402 1403 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1404 error("ssh_keysign: not installed: %s", strerror(errno)); 1405 return -1; 1406 } 1407 if (fflush(stdout) != 0) 1408 error("ssh_keysign: fflush: %s", strerror(errno)); 1409 if (pipe(to) < 0) { 1410 error("ssh_keysign: pipe: %s", strerror(errno)); 1411 return -1; 1412 } 1413 if (pipe(from) < 0) { 1414 error("ssh_keysign: pipe: %s", strerror(errno)); 1415 return -1; 1416 } 1417 if ((pid = fork()) < 0) { 1418 error("ssh_keysign: fork: %s", strerror(errno)); 1419 return -1; 1420 } 1421 if (pid == 0) { 1422 /* keep the socket on exec */ 1423 fcntl(packet_get_connection_in(), F_SETFD, 0); 1424 permanently_drop_suid(getuid()); 1425 close(from[0]); 1426 if (dup2(from[1], STDOUT_FILENO) < 0) 1427 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1428 close(to[1]); 1429 if (dup2(to[0], STDIN_FILENO) < 0) 1430 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1431 close(from[1]); 1432 close(to[0]); 1433 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1434 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1435 strerror(errno)); 1436 } 1437 close(from[1]); 1438 close(to[0]); 1439 1440 buffer_init(&b); 1441 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1442 buffer_put_string(&b, data, datalen); 1443 if (ssh_msg_send(to[1], version, &b) == -1) 1444 fatal("ssh_keysign: couldn't send request"); 1445 1446 if (ssh_msg_recv(from[0], &b) < 0) { 1447 error("ssh_keysign: no reply"); 1448 buffer_free(&b); 1449 return -1; 1450 } 1451 close(from[0]); 1452 close(to[1]); 1453 1454 while (waitpid(pid, &status, 0) < 0) 1455 if (errno != EINTR) 1456 break; 1457 1458 if (buffer_get_char(&b) != version) { 1459 error("ssh_keysign: bad version"); 1460 buffer_free(&b); 1461 return -1; 1462 } 1463 *sigp = buffer_get_string(&b, lenp); 1464 buffer_free(&b); 1465 1466 return 0; 1467 } 1468 1469 int 1470 userauth_hostbased(Authctxt *authctxt) 1471 { 1472 Key *private = NULL; 1473 Sensitive *sensitive = authctxt->sensitive; 1474 Buffer b; 1475 u_char *signature, *blob; 1476 char *chost, *pkalg, *p; 1477 const char *service; 1478 u_int blen, slen; 1479 int ok, i, found = 0; 1480 1481 /* check for a useful key */ 1482 for (i = 0; i < sensitive->nkeys; i++) { 1483 private = sensitive->keys[i]; 1484 if (private && private->type != KEY_RSA1) { 1485 found = 1; 1486 /* we take and free the key */ 1487 sensitive->keys[i] = NULL; 1488 break; 1489 } 1490 } 1491 if (!found) { 1492 debug("No more client hostkeys for hostbased authentication."); 1493 return 0; 1494 } 1495 if (key_to_blob(private, &blob, &blen) == 0) { 1496 key_free(private); 1497 return 0; 1498 } 1499 /* figure out a name for the client host */ 1500 p = get_local_name(packet_get_connection_in()); 1501 if (p == NULL) { 1502 error("userauth_hostbased: cannot get local ipaddr/name"); 1503 key_free(private); 1504 free(blob); 1505 return 0; 1506 } 1507 xasprintf(&chost, "%s.", p); 1508 debug2("userauth_hostbased: chost %s", chost); 1509 free(p); 1510 1511 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1512 authctxt->service; 1513 pkalg = xstrdup(key_ssh_name(private)); 1514 buffer_init(&b); 1515 /* construct data */ 1516 buffer_put_string(&b, session_id2, session_id2_len); 1517 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1518 buffer_put_cstring(&b, authctxt->server_user); 1519 buffer_put_cstring(&b, service); 1520 buffer_put_cstring(&b, authctxt->method->name); 1521 buffer_put_cstring(&b, pkalg); 1522 buffer_put_string(&b, blob, blen); 1523 buffer_put_cstring(&b, chost); 1524 buffer_put_cstring(&b, authctxt->local_user); 1525 #ifdef DEBUG_PK 1526 buffer_dump(&b); 1527 #endif 1528 if (sensitive->external_keysign) 1529 ok = ssh_keysign(private, &signature, &slen, 1530 buffer_ptr(&b), buffer_len(&b)); 1531 else 1532 ok = key_sign(private, &signature, &slen, 1533 buffer_ptr(&b), buffer_len(&b)); 1534 key_free(private); 1535 buffer_free(&b); 1536 if (ok != 0) { 1537 error("key_sign failed"); 1538 free(chost); 1539 free(pkalg); 1540 free(blob); 1541 return 0; 1542 } 1543 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1544 packet_put_cstring(authctxt->server_user); 1545 packet_put_cstring(authctxt->service); 1546 packet_put_cstring(authctxt->method->name); 1547 packet_put_cstring(pkalg); 1548 packet_put_string(blob, blen); 1549 packet_put_cstring(chost); 1550 packet_put_cstring(authctxt->local_user); 1551 packet_put_string(signature, slen); 1552 explicit_bzero(signature, slen); 1553 free(signature); 1554 free(chost); 1555 free(pkalg); 1556 free(blob); 1557 1558 packet_send(); 1559 return 1; 1560 } 1561 1562 /* find auth method */ 1563 1564 /* 1565 * given auth method name, if configurable options permit this method fill 1566 * in auth_ident field and return true, otherwise return false. 1567 */ 1568 static int 1569 authmethod_is_enabled(Authmethod *method) 1570 { 1571 if (method == NULL) 1572 return 0; 1573 /* return false if options indicate this method is disabled */ 1574 if (method->enabled == NULL || *method->enabled == 0) 1575 return 0; 1576 /* return false if batch mode is enabled but method needs interactive mode */ 1577 if (method->batch_flag != NULL && *method->batch_flag != 0) 1578 return 0; 1579 return 1; 1580 } 1581 1582 static Authmethod * 1583 authmethod_lookup(const char *name) 1584 { 1585 Authmethod *method = NULL; 1586 if (name != NULL) 1587 for (method = authmethods; method->name != NULL; method++) 1588 if (strcmp(name, method->name) == 0) 1589 return method; 1590 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1591 return NULL; 1592 } 1593 1594 /* XXX internal state */ 1595 static Authmethod *current = NULL; 1596 static char *supported = NULL; 1597 static char *preferred = NULL; 1598 1599 /* 1600 * Given the authentication method list sent by the server, return the 1601 * next method we should try. If the server initially sends a nil list, 1602 * use a built-in default list. 1603 */ 1604 static Authmethod * 1605 authmethod_get(char *authlist) 1606 { 1607 char *name = NULL; 1608 u_int next; 1609 1610 /* Use a suitable default if we're passed a nil list. */ 1611 if (authlist == NULL || strlen(authlist) == 0) 1612 authlist = options.preferred_authentications; 1613 1614 if (supported == NULL || strcmp(authlist, supported) != 0) { 1615 debug3("start over, passed a different list %s", authlist); 1616 free(supported); 1617 supported = xstrdup(authlist); 1618 preferred = options.preferred_authentications; 1619 debug3("preferred %s", preferred); 1620 current = NULL; 1621 } else if (current != NULL && authmethod_is_enabled(current)) 1622 return current; 1623 1624 for (;;) { 1625 if ((name = match_list(preferred, supported, &next)) == NULL) { 1626 debug("No more authentication methods to try."); 1627 current = NULL; 1628 return NULL; 1629 } 1630 preferred += next; 1631 debug3("authmethod_lookup %s", name); 1632 debug3("remaining preferred: %s", preferred); 1633 if ((current = authmethod_lookup(name)) != NULL && 1634 authmethod_is_enabled(current)) { 1635 debug3("authmethod_is_enabled %s", name); 1636 debug("Next authentication method: %s", name); 1637 free(name); 1638 return current; 1639 } 1640 free(name); 1641 } 1642 } 1643 1644 static char * 1645 authmethods_get(void) 1646 { 1647 Authmethod *method = NULL; 1648 Buffer b; 1649 char *list; 1650 1651 buffer_init(&b); 1652 for (method = authmethods; method->name != NULL; method++) { 1653 if (authmethod_is_enabled(method)) { 1654 if (buffer_len(&b) > 0) 1655 buffer_append(&b, ",", 1); 1656 buffer_append(&b, method->name, strlen(method->name)); 1657 } 1658 } 1659 buffer_append(&b, "\0", 1); 1660 list = xstrdup(buffer_ptr(&b)); 1661 buffer_free(&b); 1662 return list; 1663 } 1664 1665