1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * Copyright (c) 2008 Damien Miller. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$FreeBSD$"); 30 31 #include <sys/types.h> 32 #include <sys/socket.h> 33 #include <sys/wait.h> 34 #include <sys/stat.h> 35 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <netdb.h> 39 #include <pwd.h> 40 #include <signal.h> 41 #include <stdarg.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <unistd.h> 45 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 46 #include <vis.h> 47 #endif 48 49 #include "openbsd-compat/sys-queue.h" 50 51 #include "xmalloc.h" 52 #include "ssh.h" 53 #include "ssh2.h" 54 #include "buffer.h" 55 #include "packet.h" 56 #include "compat.h" 57 #include "cipher.h" 58 #include "key.h" 59 #include "kex.h" 60 #include "myproposal.h" 61 #include "sshconnect.h" 62 #include "authfile.h" 63 #include "dh.h" 64 #include "authfd.h" 65 #include "log.h" 66 #include "readconf.h" 67 #include "misc.h" 68 #include "match.h" 69 #include "dispatch.h" 70 #include "canohost.h" 71 #include "msg.h" 72 #include "pathnames.h" 73 #include "uidswap.h" 74 #include "hostfile.h" 75 76 #ifdef GSSAPI 77 #include "ssh-gss.h" 78 #endif 79 80 /* import */ 81 extern char *client_version_string; 82 extern char *server_version_string; 83 extern Options options; 84 #ifdef NONE_CIPHER_ENABLED 85 extern Kex *xxx_kex; 86 87 /* 88 * tty_flag is set in ssh.c so we can use it here. If set then prevent 89 * the switch to the null cipher. 90 */ 91 92 extern int tty_flag; 93 #endif 94 95 /* 96 * SSH2 key exchange 97 */ 98 99 u_char *session_id2 = NULL; 100 u_int session_id2_len = 0; 101 102 char *xxx_host; 103 struct sockaddr *xxx_hostaddr; 104 105 Kex *xxx_kex = NULL; 106 107 static int 108 verify_host_key_callback(Key *hostkey) 109 { 110 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 111 fatal("Host key verification failed."); 112 return 0; 113 } 114 115 static char * 116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 117 { 118 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 119 size_t maxlen; 120 struct hostkeys *hostkeys; 121 int ktype; 122 u_int i; 123 124 /* Find all hostkeys for this hostname */ 125 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 126 hostkeys = init_hostkeys(); 127 for (i = 0; i < options.num_user_hostfiles; i++) 128 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 129 for (i = 0; i < options.num_system_hostfiles; i++) 130 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 131 132 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 133 maxlen = strlen(avail) + 1; 134 first = xmalloc(maxlen); 135 last = xmalloc(maxlen); 136 *first = *last = '\0'; 137 138 #define ALG_APPEND(to, from) \ 139 do { \ 140 if (*to != '\0') \ 141 strlcat(to, ",", maxlen); \ 142 strlcat(to, from, maxlen); \ 143 } while (0) 144 145 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 146 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 147 fatal("%s: unknown alg %s", __func__, alg); 148 if (lookup_key_in_hostkeys_by_type(hostkeys, 149 key_type_plain(ktype), NULL)) 150 ALG_APPEND(first, alg); 151 else 152 ALG_APPEND(last, alg); 153 } 154 #undef ALG_APPEND 155 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 156 if (*first != '\0') 157 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 158 159 free(first); 160 free(last); 161 free(hostname); 162 free(oavail); 163 free_hostkeys(hostkeys); 164 165 return ret; 166 } 167 168 void 169 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 170 { 171 Kex *kex; 172 173 xxx_host = host; 174 xxx_hostaddr = hostaddr; 175 176 if (options.ciphers == (char *)-1) { 177 logit("No valid ciphers for protocol version 2 given, using defaults."); 178 options.ciphers = NULL; 179 } 180 if (options.ciphers != NULL) { 181 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 182 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 183 } 184 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 185 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 186 myproposal[PROPOSAL_ENC_ALGS_STOC] = 187 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 188 if (options.compression) { 189 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 190 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 191 } else { 192 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 193 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 194 } 195 if (options.macs != NULL) { 196 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 197 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 198 } 199 if (options.hostkeyalgorithms != NULL) 200 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 201 compat_pkalg_proposal(options.hostkeyalgorithms); 202 else { 203 /* Prefer algorithms that we already have keys for */ 204 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 205 compat_pkalg_proposal( 206 order_hostkeyalgs(host, hostaddr, port)); 207 } 208 if (options.kex_algorithms != NULL) 209 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 210 211 if (options.rekey_limit || options.rekey_interval) 212 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 213 (time_t)options.rekey_interval); 214 215 /* start key exchange */ 216 kex = kex_setup(myproposal); 217 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 218 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 219 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 220 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 221 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 222 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 223 kex->client_version_string=client_version_string; 224 kex->server_version_string=server_version_string; 225 kex->verify_host_key=&verify_host_key_callback; 226 227 xxx_kex = kex; 228 229 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 230 231 if (options.use_roaming && !kex->roaming) { 232 debug("Roaming not allowed by server"); 233 options.use_roaming = 0; 234 } 235 236 session_id2 = kex->session_id; 237 session_id2_len = kex->session_id_len; 238 239 #ifdef DEBUG_KEXDH 240 /* send 1st encrypted/maced/compressed message */ 241 packet_start(SSH2_MSG_IGNORE); 242 packet_put_cstring("markus"); 243 packet_send(); 244 packet_write_wait(); 245 #endif 246 } 247 248 /* 249 * Authenticate user 250 */ 251 252 typedef struct Authctxt Authctxt; 253 typedef struct Authmethod Authmethod; 254 typedef struct identity Identity; 255 typedef struct idlist Idlist; 256 257 struct identity { 258 TAILQ_ENTRY(identity) next; 259 AuthenticationConnection *ac; /* set if agent supports key */ 260 Key *key; /* public/private key */ 261 char *filename; /* comment for agent-only keys */ 262 int tried; 263 int isprivate; /* key points to the private key */ 264 int userprovided; 265 }; 266 TAILQ_HEAD(idlist, identity); 267 268 struct Authctxt { 269 const char *server_user; 270 const char *local_user; 271 const char *host; 272 const char *service; 273 Authmethod *method; 274 sig_atomic_t success; 275 char *authlist; 276 /* pubkey */ 277 Idlist keys; 278 AuthenticationConnection *agent; 279 /* hostbased */ 280 Sensitive *sensitive; 281 /* kbd-interactive */ 282 int info_req_seen; 283 /* generic */ 284 void *methoddata; 285 }; 286 struct Authmethod { 287 char *name; /* string to compare against server's list */ 288 int (*userauth)(Authctxt *authctxt); 289 void (*cleanup)(Authctxt *authctxt); 290 int *enabled; /* flag in option struct that enables method */ 291 int *batch_flag; /* flag in option struct that disables method */ 292 }; 293 294 void input_userauth_success(int, u_int32_t, void *); 295 void input_userauth_success_unexpected(int, u_int32_t, void *); 296 void input_userauth_failure(int, u_int32_t, void *); 297 void input_userauth_banner(int, u_int32_t, void *); 298 void input_userauth_error(int, u_int32_t, void *); 299 void input_userauth_info_req(int, u_int32_t, void *); 300 void input_userauth_pk_ok(int, u_int32_t, void *); 301 void input_userauth_passwd_changereq(int, u_int32_t, void *); 302 303 int userauth_none(Authctxt *); 304 int userauth_pubkey(Authctxt *); 305 int userauth_passwd(Authctxt *); 306 int userauth_kbdint(Authctxt *); 307 int userauth_hostbased(Authctxt *); 308 309 #ifdef GSSAPI 310 int userauth_gssapi(Authctxt *authctxt); 311 void input_gssapi_response(int type, u_int32_t, void *); 312 void input_gssapi_token(int type, u_int32_t, void *); 313 void input_gssapi_hash(int type, u_int32_t, void *); 314 void input_gssapi_error(int, u_int32_t, void *); 315 void input_gssapi_errtok(int, u_int32_t, void *); 316 #endif 317 318 void userauth(Authctxt *, char *); 319 320 static int sign_and_send_pubkey(Authctxt *, Identity *); 321 static void pubkey_prepare(Authctxt *); 322 static void pubkey_cleanup(Authctxt *); 323 static Key *load_identity_file(char *, int); 324 325 static Authmethod *authmethod_get(char *authlist); 326 static Authmethod *authmethod_lookup(const char *name); 327 static char *authmethods_get(void); 328 329 Authmethod authmethods[] = { 330 #ifdef GSSAPI 331 {"gssapi-with-mic", 332 userauth_gssapi, 333 NULL, 334 &options.gss_authentication, 335 NULL}, 336 #endif 337 {"hostbased", 338 userauth_hostbased, 339 NULL, 340 &options.hostbased_authentication, 341 NULL}, 342 {"publickey", 343 userauth_pubkey, 344 NULL, 345 &options.pubkey_authentication, 346 NULL}, 347 {"keyboard-interactive", 348 userauth_kbdint, 349 NULL, 350 &options.kbd_interactive_authentication, 351 &options.batch_mode}, 352 {"password", 353 userauth_passwd, 354 NULL, 355 &options.password_authentication, 356 &options.batch_mode}, 357 {"none", 358 userauth_none, 359 NULL, 360 NULL, 361 NULL}, 362 {NULL, NULL, NULL, NULL, NULL} 363 }; 364 365 void 366 ssh_userauth2(const char *local_user, const char *server_user, char *host, 367 Sensitive *sensitive) 368 { 369 Authctxt authctxt; 370 int type; 371 372 if (options.challenge_response_authentication) 373 options.kbd_interactive_authentication = 1; 374 375 packet_start(SSH2_MSG_SERVICE_REQUEST); 376 packet_put_cstring("ssh-userauth"); 377 packet_send(); 378 debug("SSH2_MSG_SERVICE_REQUEST sent"); 379 packet_write_wait(); 380 type = packet_read(); 381 if (type != SSH2_MSG_SERVICE_ACCEPT) 382 fatal("Server denied authentication request: %d", type); 383 if (packet_remaining() > 0) { 384 char *reply = packet_get_string(NULL); 385 debug2("service_accept: %s", reply); 386 free(reply); 387 } else { 388 debug2("buggy server: service_accept w/o service"); 389 } 390 packet_check_eom(); 391 debug("SSH2_MSG_SERVICE_ACCEPT received"); 392 393 if (options.preferred_authentications == NULL) 394 options.preferred_authentications = authmethods_get(); 395 396 /* setup authentication context */ 397 memset(&authctxt, 0, sizeof(authctxt)); 398 pubkey_prepare(&authctxt); 399 authctxt.server_user = server_user; 400 authctxt.local_user = local_user; 401 authctxt.host = host; 402 authctxt.service = "ssh-connection"; /* service name */ 403 authctxt.success = 0; 404 authctxt.method = authmethod_lookup("none"); 405 authctxt.authlist = NULL; 406 authctxt.methoddata = NULL; 407 authctxt.sensitive = sensitive; 408 authctxt.info_req_seen = 0; 409 if (authctxt.method == NULL) 410 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 411 412 /* initial userauth request */ 413 userauth_none(&authctxt); 414 415 dispatch_init(&input_userauth_error); 416 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 417 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 418 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 419 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 420 421 pubkey_cleanup(&authctxt); 422 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 423 424 #ifdef NONE_CIPHER_ENABLED 425 /* 426 * If the user explicitly requests to use the none cipher enable it 427 * post authentication and only if the right conditions are met: both 428 * of the NONE switches must be true and there must be no tty allocated. 429 */ 430 if (options.none_switch == 1 && options.none_enabled == 1) { 431 if (!tty_flag) { 432 debug("Requesting none cipher re-keying..."); 433 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 434 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 435 kex_prop2buf(&xxx_kex->my, myproposal); 436 packet_request_rekeying(); 437 fprintf(stderr, "WARNING: enabled NONE cipher\n"); 438 } else { 439 /* Requested NONE cipher on an interactive session. */ 440 debug("Cannot switch to NONE cipher with tty " 441 "allocated"); 442 fprintf(stderr, "NONE cipher switch disabled given " 443 "a TTY is allocated\n"); 444 } 445 } 446 #endif 447 debug("Authentication succeeded (%s).", authctxt.method->name); 448 } 449 450 void 451 userauth(Authctxt *authctxt, char *authlist) 452 { 453 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 454 authctxt->method->cleanup(authctxt); 455 456 free(authctxt->methoddata); 457 authctxt->methoddata = NULL; 458 if (authlist == NULL) { 459 authlist = authctxt->authlist; 460 } else { 461 free(authctxt->authlist); 462 authctxt->authlist = authlist; 463 } 464 for (;;) { 465 Authmethod *method = authmethod_get(authlist); 466 if (method == NULL) 467 fatal("Permission denied (%s).", authlist); 468 authctxt->method = method; 469 470 /* reset the per method handler */ 471 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 472 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 473 474 /* and try new method */ 475 if (method->userauth(authctxt) != 0) { 476 debug2("we sent a %s packet, wait for reply", method->name); 477 break; 478 } else { 479 debug2("we did not send a packet, disable method"); 480 method->enabled = NULL; 481 } 482 } 483 } 484 485 /* ARGSUSED */ 486 void 487 input_userauth_error(int type, u_int32_t seq, void *ctxt) 488 { 489 fatal("input_userauth_error: bad message during authentication: " 490 "type %d", type); 491 } 492 493 /* ARGSUSED */ 494 void 495 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 496 { 497 char *msg, *raw, *lang; 498 u_int len; 499 500 debug3("input_userauth_banner"); 501 raw = packet_get_string(&len); 502 lang = packet_get_string(NULL); 503 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 504 if (len > 65536) 505 len = 65536; 506 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 507 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 508 fprintf(stderr, "%s", msg); 509 free(msg); 510 } 511 free(raw); 512 free(lang); 513 } 514 515 /* ARGSUSED */ 516 void 517 input_userauth_success(int type, u_int32_t seq, void *ctxt) 518 { 519 Authctxt *authctxt = ctxt; 520 521 if (authctxt == NULL) 522 fatal("input_userauth_success: no authentication context"); 523 free(authctxt->authlist); 524 authctxt->authlist = NULL; 525 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 526 authctxt->method->cleanup(authctxt); 527 free(authctxt->methoddata); 528 authctxt->methoddata = NULL; 529 authctxt->success = 1; /* break out */ 530 } 531 532 void 533 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 534 { 535 Authctxt *authctxt = ctxt; 536 537 if (authctxt == NULL) 538 fatal("%s: no authentication context", __func__); 539 540 fatal("Unexpected authentication success during %s.", 541 authctxt->method->name); 542 } 543 544 /* ARGSUSED */ 545 void 546 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 547 { 548 Authctxt *authctxt = ctxt; 549 char *authlist = NULL; 550 int partial; 551 552 if (authctxt == NULL) 553 fatal("input_userauth_failure: no authentication context"); 554 555 authlist = packet_get_string(NULL); 556 partial = packet_get_char(); 557 packet_check_eom(); 558 559 if (partial != 0) { 560 logit("Authenticated with partial success."); 561 /* reset state */ 562 pubkey_cleanup(authctxt); 563 pubkey_prepare(authctxt); 564 } 565 debug("Authentications that can continue: %s", authlist); 566 567 userauth(authctxt, authlist); 568 } 569 570 /* ARGSUSED */ 571 void 572 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 573 { 574 Authctxt *authctxt = ctxt; 575 Key *key = NULL; 576 Identity *id = NULL; 577 Buffer b; 578 int pktype, sent = 0; 579 u_int alen, blen; 580 char *pkalg, *fp; 581 u_char *pkblob; 582 583 if (authctxt == NULL) 584 fatal("input_userauth_pk_ok: no authentication context"); 585 if (datafellows & SSH_BUG_PKOK) { 586 /* this is similar to SSH_BUG_PKAUTH */ 587 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 588 pkblob = packet_get_string(&blen); 589 buffer_init(&b); 590 buffer_append(&b, pkblob, blen); 591 pkalg = buffer_get_string(&b, &alen); 592 buffer_free(&b); 593 } else { 594 pkalg = packet_get_string(&alen); 595 pkblob = packet_get_string(&blen); 596 } 597 packet_check_eom(); 598 599 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 600 601 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 602 debug("unknown pkalg %s", pkalg); 603 goto done; 604 } 605 if ((key = key_from_blob(pkblob, blen)) == NULL) { 606 debug("no key from blob. pkalg %s", pkalg); 607 goto done; 608 } 609 if (key->type != pktype) { 610 error("input_userauth_pk_ok: type mismatch " 611 "for decoded key (received %d, expected %d)", 612 key->type, pktype); 613 goto done; 614 } 615 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 616 debug2("input_userauth_pk_ok: fp %s", fp); 617 free(fp); 618 619 /* 620 * search keys in the reverse order, because last candidate has been 621 * moved to the end of the queue. this also avoids confusion by 622 * duplicate keys 623 */ 624 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 625 if (key_equal(key, id->key)) { 626 sent = sign_and_send_pubkey(authctxt, id); 627 break; 628 } 629 } 630 done: 631 if (key != NULL) 632 key_free(key); 633 free(pkalg); 634 free(pkblob); 635 636 /* try another method if we did not send a packet */ 637 if (sent == 0) 638 userauth(authctxt, NULL); 639 } 640 641 #ifdef GSSAPI 642 int 643 userauth_gssapi(Authctxt *authctxt) 644 { 645 Gssctxt *gssctxt = NULL; 646 static gss_OID_set gss_supported = NULL; 647 static u_int mech = 0; 648 OM_uint32 min; 649 int ok = 0; 650 651 /* Try one GSSAPI method at a time, rather than sending them all at 652 * once. */ 653 654 if (gss_supported == NULL) 655 gss_indicate_mechs(&min, &gss_supported); 656 657 /* Check to see if the mechanism is usable before we offer it */ 658 while (mech < gss_supported->count && !ok) { 659 /* My DER encoding requires length<128 */ 660 if (gss_supported->elements[mech].length < 128 && 661 ssh_gssapi_check_mechanism(&gssctxt, 662 &gss_supported->elements[mech], authctxt->host)) { 663 ok = 1; /* Mechanism works */ 664 } else { 665 mech++; 666 } 667 } 668 669 if (!ok) 670 return 0; 671 672 authctxt->methoddata=(void *)gssctxt; 673 674 packet_start(SSH2_MSG_USERAUTH_REQUEST); 675 packet_put_cstring(authctxt->server_user); 676 packet_put_cstring(authctxt->service); 677 packet_put_cstring(authctxt->method->name); 678 679 packet_put_int(1); 680 681 packet_put_int((gss_supported->elements[mech].length) + 2); 682 packet_put_char(SSH_GSS_OIDTYPE); 683 packet_put_char(gss_supported->elements[mech].length); 684 packet_put_raw(gss_supported->elements[mech].elements, 685 gss_supported->elements[mech].length); 686 687 packet_send(); 688 689 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 690 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 691 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 692 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 693 694 mech++; /* Move along to next candidate */ 695 696 return 1; 697 } 698 699 static OM_uint32 700 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 701 { 702 Authctxt *authctxt = ctxt; 703 Gssctxt *gssctxt = authctxt->methoddata; 704 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 705 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 706 gss_buffer_desc gssbuf; 707 OM_uint32 status, ms, flags; 708 Buffer b; 709 710 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 711 recv_tok, &send_tok, &flags); 712 713 if (send_tok.length > 0) { 714 if (GSS_ERROR(status)) 715 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 716 else 717 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 718 719 packet_put_string(send_tok.value, send_tok.length); 720 packet_send(); 721 gss_release_buffer(&ms, &send_tok); 722 } 723 724 if (status == GSS_S_COMPLETE) { 725 /* send either complete or MIC, depending on mechanism */ 726 if (!(flags & GSS_C_INTEG_FLAG)) { 727 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 728 packet_send(); 729 } else { 730 ssh_gssapi_buildmic(&b, authctxt->server_user, 731 authctxt->service, "gssapi-with-mic"); 732 733 gssbuf.value = buffer_ptr(&b); 734 gssbuf.length = buffer_len(&b); 735 736 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 737 738 if (!GSS_ERROR(status)) { 739 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 740 packet_put_string(mic.value, mic.length); 741 742 packet_send(); 743 } 744 745 buffer_free(&b); 746 gss_release_buffer(&ms, &mic); 747 } 748 } 749 750 return status; 751 } 752 753 /* ARGSUSED */ 754 void 755 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 756 { 757 Authctxt *authctxt = ctxt; 758 Gssctxt *gssctxt; 759 int oidlen; 760 char *oidv; 761 762 if (authctxt == NULL) 763 fatal("input_gssapi_response: no authentication context"); 764 gssctxt = authctxt->methoddata; 765 766 /* Setup our OID */ 767 oidv = packet_get_string(&oidlen); 768 769 if (oidlen <= 2 || 770 oidv[0] != SSH_GSS_OIDTYPE || 771 oidv[1] != oidlen - 2) { 772 free(oidv); 773 debug("Badly encoded mechanism OID received"); 774 userauth(authctxt, NULL); 775 return; 776 } 777 778 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 779 fatal("Server returned different OID than expected"); 780 781 packet_check_eom(); 782 783 free(oidv); 784 785 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 786 /* Start again with next method on list */ 787 debug("Trying to start again"); 788 userauth(authctxt, NULL); 789 return; 790 } 791 } 792 793 /* ARGSUSED */ 794 void 795 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 796 { 797 Authctxt *authctxt = ctxt; 798 gss_buffer_desc recv_tok; 799 OM_uint32 status; 800 u_int slen; 801 802 if (authctxt == NULL) 803 fatal("input_gssapi_response: no authentication context"); 804 805 recv_tok.value = packet_get_string(&slen); 806 recv_tok.length = slen; /* safe typecast */ 807 808 packet_check_eom(); 809 810 status = process_gssapi_token(ctxt, &recv_tok); 811 812 free(recv_tok.value); 813 814 if (GSS_ERROR(status)) { 815 /* Start again with the next method in the list */ 816 userauth(authctxt, NULL); 817 return; 818 } 819 } 820 821 /* ARGSUSED */ 822 void 823 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 824 { 825 Authctxt *authctxt = ctxt; 826 Gssctxt *gssctxt; 827 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 828 gss_buffer_desc recv_tok; 829 OM_uint32 ms; 830 u_int len; 831 832 if (authctxt == NULL) 833 fatal("input_gssapi_response: no authentication context"); 834 gssctxt = authctxt->methoddata; 835 836 recv_tok.value = packet_get_string(&len); 837 recv_tok.length = len; 838 839 packet_check_eom(); 840 841 /* Stick it into GSSAPI and see what it says */ 842 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 843 &recv_tok, &send_tok, NULL); 844 845 free(recv_tok.value); 846 gss_release_buffer(&ms, &send_tok); 847 848 /* Server will be returning a failed packet after this one */ 849 } 850 851 /* ARGSUSED */ 852 void 853 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 854 { 855 char *msg; 856 char *lang; 857 858 /* maj */(void)packet_get_int(); 859 /* min */(void)packet_get_int(); 860 msg=packet_get_string(NULL); 861 lang=packet_get_string(NULL); 862 863 packet_check_eom(); 864 865 debug("Server GSSAPI Error:\n%s", msg); 866 free(msg); 867 free(lang); 868 } 869 #endif /* GSSAPI */ 870 871 int 872 userauth_none(Authctxt *authctxt) 873 { 874 /* initial userauth request */ 875 packet_start(SSH2_MSG_USERAUTH_REQUEST); 876 packet_put_cstring(authctxt->server_user); 877 packet_put_cstring(authctxt->service); 878 packet_put_cstring(authctxt->method->name); 879 packet_send(); 880 return 1; 881 } 882 883 int 884 userauth_passwd(Authctxt *authctxt) 885 { 886 static int attempt = 0; 887 char prompt[150]; 888 char *password; 889 const char *host = options.host_key_alias ? options.host_key_alias : 890 authctxt->host; 891 892 if (attempt++ >= options.number_of_password_prompts) 893 return 0; 894 895 if (attempt != 1) 896 error("Permission denied, please try again."); 897 898 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 899 authctxt->server_user, host); 900 password = read_passphrase(prompt, 0); 901 packet_start(SSH2_MSG_USERAUTH_REQUEST); 902 packet_put_cstring(authctxt->server_user); 903 packet_put_cstring(authctxt->service); 904 packet_put_cstring(authctxt->method->name); 905 packet_put_char(0); 906 packet_put_cstring(password); 907 explicit_bzero(password, strlen(password)); 908 free(password); 909 packet_add_padding(64); 910 packet_send(); 911 912 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 913 &input_userauth_passwd_changereq); 914 915 return 1; 916 } 917 918 /* 919 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 920 */ 921 /* ARGSUSED */ 922 void 923 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 924 { 925 Authctxt *authctxt = ctxt; 926 char *info, *lang, *password = NULL, *retype = NULL; 927 char prompt[150]; 928 const char *host = options.host_key_alias ? options.host_key_alias : 929 authctxt->host; 930 931 debug2("input_userauth_passwd_changereq"); 932 933 if (authctxt == NULL) 934 fatal("input_userauth_passwd_changereq: " 935 "no authentication context"); 936 937 info = packet_get_string(NULL); 938 lang = packet_get_string(NULL); 939 if (strlen(info) > 0) 940 logit("%s", info); 941 free(info); 942 free(lang); 943 packet_start(SSH2_MSG_USERAUTH_REQUEST); 944 packet_put_cstring(authctxt->server_user); 945 packet_put_cstring(authctxt->service); 946 packet_put_cstring(authctxt->method->name); 947 packet_put_char(1); /* additional info */ 948 snprintf(prompt, sizeof(prompt), 949 "Enter %.30s@%.128s's old password: ", 950 authctxt->server_user, host); 951 password = read_passphrase(prompt, 0); 952 packet_put_cstring(password); 953 explicit_bzero(password, strlen(password)); 954 free(password); 955 password = NULL; 956 while (password == NULL) { 957 snprintf(prompt, sizeof(prompt), 958 "Enter %.30s@%.128s's new password: ", 959 authctxt->server_user, host); 960 password = read_passphrase(prompt, RP_ALLOW_EOF); 961 if (password == NULL) { 962 /* bail out */ 963 return; 964 } 965 snprintf(prompt, sizeof(prompt), 966 "Retype %.30s@%.128s's new password: ", 967 authctxt->server_user, host); 968 retype = read_passphrase(prompt, 0); 969 if (strcmp(password, retype) != 0) { 970 explicit_bzero(password, strlen(password)); 971 free(password); 972 logit("Mismatch; try again, EOF to quit."); 973 password = NULL; 974 } 975 explicit_bzero(retype, strlen(retype)); 976 free(retype); 977 } 978 packet_put_cstring(password); 979 explicit_bzero(password, strlen(password)); 980 free(password); 981 packet_add_padding(64); 982 packet_send(); 983 984 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 985 &input_userauth_passwd_changereq); 986 } 987 988 static int 989 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 990 u_char *data, u_int datalen) 991 { 992 Key *prv; 993 int ret; 994 995 /* the agent supports this key */ 996 if (id->ac) 997 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 998 data, datalen)); 999 /* 1000 * we have already loaded the private key or 1001 * the private key is stored in external hardware 1002 */ 1003 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1004 return (key_sign(id->key, sigp, lenp, data, datalen)); 1005 /* load the private key from the file */ 1006 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 1007 return (-1); 1008 ret = key_sign(prv, sigp, lenp, data, datalen); 1009 key_free(prv); 1010 return (ret); 1011 } 1012 1013 static int 1014 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1015 { 1016 Buffer b; 1017 u_char *blob, *signature; 1018 u_int bloblen, slen; 1019 u_int skip = 0; 1020 int ret = -1; 1021 int have_sig = 1; 1022 char *fp; 1023 1024 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1025 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1026 free(fp); 1027 1028 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1029 /* we cannot handle this key */ 1030 debug3("sign_and_send_pubkey: cannot handle key"); 1031 return 0; 1032 } 1033 /* data to be signed */ 1034 buffer_init(&b); 1035 if (datafellows & SSH_OLD_SESSIONID) { 1036 buffer_append(&b, session_id2, session_id2_len); 1037 skip = session_id2_len; 1038 } else { 1039 buffer_put_string(&b, session_id2, session_id2_len); 1040 skip = buffer_len(&b); 1041 } 1042 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1043 buffer_put_cstring(&b, authctxt->server_user); 1044 buffer_put_cstring(&b, 1045 datafellows & SSH_BUG_PKSERVICE ? 1046 "ssh-userauth" : 1047 authctxt->service); 1048 if (datafellows & SSH_BUG_PKAUTH) { 1049 buffer_put_char(&b, have_sig); 1050 } else { 1051 buffer_put_cstring(&b, authctxt->method->name); 1052 buffer_put_char(&b, have_sig); 1053 buffer_put_cstring(&b, key_ssh_name(id->key)); 1054 } 1055 buffer_put_string(&b, blob, bloblen); 1056 1057 /* generate signature */ 1058 ret = identity_sign(id, &signature, &slen, 1059 buffer_ptr(&b), buffer_len(&b)); 1060 if (ret == -1) { 1061 free(blob); 1062 buffer_free(&b); 1063 return 0; 1064 } 1065 #ifdef DEBUG_PK 1066 buffer_dump(&b); 1067 #endif 1068 if (datafellows & SSH_BUG_PKSERVICE) { 1069 buffer_clear(&b); 1070 buffer_append(&b, session_id2, session_id2_len); 1071 skip = session_id2_len; 1072 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1073 buffer_put_cstring(&b, authctxt->server_user); 1074 buffer_put_cstring(&b, authctxt->service); 1075 buffer_put_cstring(&b, authctxt->method->name); 1076 buffer_put_char(&b, have_sig); 1077 if (!(datafellows & SSH_BUG_PKAUTH)) 1078 buffer_put_cstring(&b, key_ssh_name(id->key)); 1079 buffer_put_string(&b, blob, bloblen); 1080 } 1081 free(blob); 1082 1083 /* append signature */ 1084 buffer_put_string(&b, signature, slen); 1085 free(signature); 1086 1087 /* skip session id and packet type */ 1088 if (buffer_len(&b) < skip + 1) 1089 fatal("userauth_pubkey: internal error"); 1090 buffer_consume(&b, skip + 1); 1091 1092 /* put remaining data from buffer into packet */ 1093 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1094 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1095 buffer_free(&b); 1096 packet_send(); 1097 1098 return 1; 1099 } 1100 1101 static int 1102 send_pubkey_test(Authctxt *authctxt, Identity *id) 1103 { 1104 u_char *blob; 1105 u_int bloblen, have_sig = 0; 1106 1107 debug3("send_pubkey_test"); 1108 1109 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1110 /* we cannot handle this key */ 1111 debug3("send_pubkey_test: cannot handle key"); 1112 return 0; 1113 } 1114 /* register callback for USERAUTH_PK_OK message */ 1115 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1116 1117 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1118 packet_put_cstring(authctxt->server_user); 1119 packet_put_cstring(authctxt->service); 1120 packet_put_cstring(authctxt->method->name); 1121 packet_put_char(have_sig); 1122 if (!(datafellows & SSH_BUG_PKAUTH)) 1123 packet_put_cstring(key_ssh_name(id->key)); 1124 packet_put_string(blob, bloblen); 1125 free(blob); 1126 packet_send(); 1127 return 1; 1128 } 1129 1130 static Key * 1131 load_identity_file(char *filename, int userprovided) 1132 { 1133 Key *private; 1134 char prompt[300], *passphrase; 1135 int perm_ok = 0, quit, i; 1136 struct stat st; 1137 1138 if (stat(filename, &st) < 0) { 1139 (userprovided ? logit : debug3)("no such identity: %s: %s", 1140 filename, strerror(errno)); 1141 return NULL; 1142 } 1143 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1144 if (!perm_ok) { 1145 if (private != NULL) 1146 key_free(private); 1147 return NULL; 1148 } 1149 if (private == NULL) { 1150 if (options.batch_mode) 1151 return NULL; 1152 snprintf(prompt, sizeof prompt, 1153 "Enter passphrase for key '%.100s': ", filename); 1154 for (i = 0; i < options.number_of_password_prompts; i++) { 1155 passphrase = read_passphrase(prompt, 0); 1156 if (strcmp(passphrase, "") != 0) { 1157 private = key_load_private_type(KEY_UNSPEC, 1158 filename, passphrase, NULL, NULL); 1159 quit = 0; 1160 } else { 1161 debug2("no passphrase given, try next key"); 1162 quit = 1; 1163 } 1164 explicit_bzero(passphrase, strlen(passphrase)); 1165 free(passphrase); 1166 if (private != NULL || quit) 1167 break; 1168 debug2("bad passphrase given, try again..."); 1169 } 1170 } 1171 return private; 1172 } 1173 1174 /* 1175 * try keys in the following order: 1176 * 1. agent keys that are found in the config file 1177 * 2. other agent keys 1178 * 3. keys that are only listed in the config file 1179 */ 1180 static void 1181 pubkey_prepare(Authctxt *authctxt) 1182 { 1183 Identity *id, *id2, *tmp; 1184 Idlist agent, files, *preferred; 1185 Key *key; 1186 AuthenticationConnection *ac; 1187 char *comment; 1188 int i, found; 1189 1190 TAILQ_INIT(&agent); /* keys from the agent */ 1191 TAILQ_INIT(&files); /* keys from the config file */ 1192 preferred = &authctxt->keys; 1193 TAILQ_INIT(preferred); /* preferred order of keys */ 1194 1195 /* list of keys stored in the filesystem and PKCS#11 */ 1196 for (i = 0; i < options.num_identity_files; i++) { 1197 key = options.identity_keys[i]; 1198 if (key && key->type == KEY_RSA1) 1199 continue; 1200 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1201 continue; 1202 options.identity_keys[i] = NULL; 1203 id = xcalloc(1, sizeof(*id)); 1204 id->key = key; 1205 id->filename = xstrdup(options.identity_files[i]); 1206 id->userprovided = options.identity_file_userprovided[i]; 1207 TAILQ_INSERT_TAIL(&files, id, next); 1208 } 1209 /* Prefer PKCS11 keys that are explicitly listed */ 1210 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1211 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0) 1212 continue; 1213 found = 0; 1214 TAILQ_FOREACH(id2, &files, next) { 1215 if (id2->key == NULL || 1216 (id2->key->flags & KEY_FLAG_EXT) != 0) 1217 continue; 1218 if (key_equal(id->key, id2->key)) { 1219 TAILQ_REMOVE(&files, id, next); 1220 TAILQ_INSERT_TAIL(preferred, id, next); 1221 found = 1; 1222 break; 1223 } 1224 } 1225 /* If IdentitiesOnly set and key not found then don't use it */ 1226 if (!found && options.identities_only) { 1227 TAILQ_REMOVE(&files, id, next); 1228 explicit_bzero(id, sizeof(*id)); 1229 free(id); 1230 } 1231 } 1232 /* list of keys supported by the agent */ 1233 if ((ac = ssh_get_authentication_connection())) { 1234 for (key = ssh_get_first_identity(ac, &comment, 2); 1235 key != NULL; 1236 key = ssh_get_next_identity(ac, &comment, 2)) { 1237 found = 0; 1238 TAILQ_FOREACH(id, &files, next) { 1239 /* agent keys from the config file are preferred */ 1240 if (key_equal(key, id->key)) { 1241 key_free(key); 1242 free(comment); 1243 TAILQ_REMOVE(&files, id, next); 1244 TAILQ_INSERT_TAIL(preferred, id, next); 1245 id->ac = ac; 1246 found = 1; 1247 break; 1248 } 1249 } 1250 if (!found && !options.identities_only) { 1251 id = xcalloc(1, sizeof(*id)); 1252 id->key = key; 1253 id->filename = comment; 1254 id->ac = ac; 1255 TAILQ_INSERT_TAIL(&agent, id, next); 1256 } 1257 } 1258 /* append remaining agent keys */ 1259 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1260 TAILQ_REMOVE(&agent, id, next); 1261 TAILQ_INSERT_TAIL(preferred, id, next); 1262 } 1263 authctxt->agent = ac; 1264 } 1265 /* append remaining keys from the config file */ 1266 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1267 TAILQ_REMOVE(&files, id, next); 1268 TAILQ_INSERT_TAIL(preferred, id, next); 1269 } 1270 TAILQ_FOREACH(id, preferred, next) { 1271 debug2("key: %s (%p),%s", id->filename, id->key, 1272 id->userprovided ? " explicit" : ""); 1273 } 1274 } 1275 1276 static void 1277 pubkey_cleanup(Authctxt *authctxt) 1278 { 1279 Identity *id; 1280 1281 if (authctxt->agent != NULL) 1282 ssh_close_authentication_connection(authctxt->agent); 1283 for (id = TAILQ_FIRST(&authctxt->keys); id; 1284 id = TAILQ_FIRST(&authctxt->keys)) { 1285 TAILQ_REMOVE(&authctxt->keys, id, next); 1286 if (id->key) 1287 key_free(id->key); 1288 free(id->filename); 1289 free(id); 1290 } 1291 } 1292 1293 int 1294 userauth_pubkey(Authctxt *authctxt) 1295 { 1296 Identity *id; 1297 int sent = 0; 1298 1299 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1300 if (id->tried++) 1301 return (0); 1302 /* move key to the end of the queue */ 1303 TAILQ_REMOVE(&authctxt->keys, id, next); 1304 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1305 /* 1306 * send a test message if we have the public key. for 1307 * encrypted keys we cannot do this and have to load the 1308 * private key instead 1309 */ 1310 if (id->key != NULL) { 1311 if (key_type_plain(id->key->type) == KEY_RSA && 1312 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1313 debug("Skipped %s key %s for RSA/MD5 server", 1314 key_type(id->key), id->filename); 1315 } else if (id->key->type != KEY_RSA1) { 1316 debug("Offering %s public key: %s", 1317 key_type(id->key), id->filename); 1318 sent = send_pubkey_test(authctxt, id); 1319 } 1320 } else { 1321 debug("Trying private key: %s", id->filename); 1322 id->key = load_identity_file(id->filename, 1323 id->userprovided); 1324 if (id->key != NULL) { 1325 id->isprivate = 1; 1326 if (key_type_plain(id->key->type) == KEY_RSA && 1327 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1328 debug("Skipped %s key %s for RSA/MD5 " 1329 "server", key_type(id->key), 1330 id->filename); 1331 } else { 1332 sent = sign_and_send_pubkey( 1333 authctxt, id); 1334 } 1335 key_free(id->key); 1336 id->key = NULL; 1337 } 1338 } 1339 if (sent) 1340 return (sent); 1341 } 1342 return (0); 1343 } 1344 1345 /* 1346 * Send userauth request message specifying keyboard-interactive method. 1347 */ 1348 int 1349 userauth_kbdint(Authctxt *authctxt) 1350 { 1351 static int attempt = 0; 1352 1353 if (attempt++ >= options.number_of_password_prompts) 1354 return 0; 1355 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1356 if (attempt > 1 && !authctxt->info_req_seen) { 1357 debug3("userauth_kbdint: disable: no info_req_seen"); 1358 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1359 return 0; 1360 } 1361 1362 debug2("userauth_kbdint"); 1363 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1364 packet_put_cstring(authctxt->server_user); 1365 packet_put_cstring(authctxt->service); 1366 packet_put_cstring(authctxt->method->name); 1367 packet_put_cstring(""); /* lang */ 1368 packet_put_cstring(options.kbd_interactive_devices ? 1369 options.kbd_interactive_devices : ""); 1370 packet_send(); 1371 1372 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1373 return 1; 1374 } 1375 1376 /* 1377 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1378 */ 1379 void 1380 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1381 { 1382 Authctxt *authctxt = ctxt; 1383 char *name, *inst, *lang, *prompt, *response; 1384 u_int num_prompts, i; 1385 int echo = 0; 1386 1387 debug2("input_userauth_info_req"); 1388 1389 if (authctxt == NULL) 1390 fatal("input_userauth_info_req: no authentication context"); 1391 1392 authctxt->info_req_seen = 1; 1393 1394 name = packet_get_string(NULL); 1395 inst = packet_get_string(NULL); 1396 lang = packet_get_string(NULL); 1397 if (strlen(name) > 0) 1398 logit("%s", name); 1399 if (strlen(inst) > 0) 1400 logit("%s", inst); 1401 free(name); 1402 free(inst); 1403 free(lang); 1404 1405 num_prompts = packet_get_int(); 1406 /* 1407 * Begin to build info response packet based on prompts requested. 1408 * We commit to providing the correct number of responses, so if 1409 * further on we run into a problem that prevents this, we have to 1410 * be sure and clean this up and send a correct error response. 1411 */ 1412 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1413 packet_put_int(num_prompts); 1414 1415 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1416 for (i = 0; i < num_prompts; i++) { 1417 prompt = packet_get_string(NULL); 1418 echo = packet_get_char(); 1419 1420 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1421 1422 packet_put_cstring(response); 1423 explicit_bzero(response, strlen(response)); 1424 free(response); 1425 free(prompt); 1426 } 1427 packet_check_eom(); /* done with parsing incoming message. */ 1428 1429 packet_add_padding(64); 1430 packet_send(); 1431 } 1432 1433 static int 1434 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1435 u_char *data, u_int datalen) 1436 { 1437 Buffer b; 1438 struct stat st; 1439 pid_t pid; 1440 int to[2], from[2], status, version = 2; 1441 1442 debug2("ssh_keysign called"); 1443 1444 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1445 error("ssh_keysign: not installed: %s", strerror(errno)); 1446 return -1; 1447 } 1448 if (fflush(stdout) != 0) 1449 error("ssh_keysign: fflush: %s", strerror(errno)); 1450 if (pipe(to) < 0) { 1451 error("ssh_keysign: pipe: %s", strerror(errno)); 1452 return -1; 1453 } 1454 if (pipe(from) < 0) { 1455 error("ssh_keysign: pipe: %s", strerror(errno)); 1456 return -1; 1457 } 1458 if ((pid = fork()) < 0) { 1459 error("ssh_keysign: fork: %s", strerror(errno)); 1460 return -1; 1461 } 1462 if (pid == 0) { 1463 /* keep the socket on exec */ 1464 fcntl(packet_get_connection_in(), F_SETFD, 0); 1465 permanently_drop_suid(getuid()); 1466 close(from[0]); 1467 if (dup2(from[1], STDOUT_FILENO) < 0) 1468 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1469 close(to[1]); 1470 if (dup2(to[0], STDIN_FILENO) < 0) 1471 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1472 close(from[1]); 1473 close(to[0]); 1474 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1475 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1476 strerror(errno)); 1477 } 1478 close(from[1]); 1479 close(to[0]); 1480 1481 buffer_init(&b); 1482 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1483 buffer_put_string(&b, data, datalen); 1484 if (ssh_msg_send(to[1], version, &b) == -1) 1485 fatal("ssh_keysign: couldn't send request"); 1486 1487 if (ssh_msg_recv(from[0], &b) < 0) { 1488 error("ssh_keysign: no reply"); 1489 buffer_free(&b); 1490 return -1; 1491 } 1492 close(from[0]); 1493 close(to[1]); 1494 1495 while (waitpid(pid, &status, 0) < 0) 1496 if (errno != EINTR) 1497 break; 1498 1499 if (buffer_get_char(&b) != version) { 1500 error("ssh_keysign: bad version"); 1501 buffer_free(&b); 1502 return -1; 1503 } 1504 *sigp = buffer_get_string(&b, lenp); 1505 buffer_free(&b); 1506 1507 return 0; 1508 } 1509 1510 int 1511 userauth_hostbased(Authctxt *authctxt) 1512 { 1513 Key *private = NULL; 1514 Sensitive *sensitive = authctxt->sensitive; 1515 Buffer b; 1516 u_char *signature, *blob; 1517 char *chost, *pkalg, *p; 1518 const char *service; 1519 u_int blen, slen; 1520 int ok, i, found = 0; 1521 1522 /* check for a useful key */ 1523 for (i = 0; i < sensitive->nkeys; i++) { 1524 private = sensitive->keys[i]; 1525 if (private && private->type != KEY_RSA1) { 1526 found = 1; 1527 /* we take and free the key */ 1528 sensitive->keys[i] = NULL; 1529 break; 1530 } 1531 } 1532 if (!found) { 1533 debug("No more client hostkeys for hostbased authentication."); 1534 return 0; 1535 } 1536 if (key_to_blob(private, &blob, &blen) == 0) { 1537 key_free(private); 1538 return 0; 1539 } 1540 /* figure out a name for the client host */ 1541 p = get_local_name(packet_get_connection_in()); 1542 if (p == NULL) { 1543 error("userauth_hostbased: cannot get local ipaddr/name"); 1544 key_free(private); 1545 free(blob); 1546 return 0; 1547 } 1548 xasprintf(&chost, "%s.", p); 1549 debug2("userauth_hostbased: chost %s", chost); 1550 free(p); 1551 1552 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1553 authctxt->service; 1554 pkalg = xstrdup(key_ssh_name(private)); 1555 buffer_init(&b); 1556 /* construct data */ 1557 buffer_put_string(&b, session_id2, session_id2_len); 1558 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1559 buffer_put_cstring(&b, authctxt->server_user); 1560 buffer_put_cstring(&b, service); 1561 buffer_put_cstring(&b, authctxt->method->name); 1562 buffer_put_cstring(&b, pkalg); 1563 buffer_put_string(&b, blob, blen); 1564 buffer_put_cstring(&b, chost); 1565 buffer_put_cstring(&b, authctxt->local_user); 1566 #ifdef DEBUG_PK 1567 buffer_dump(&b); 1568 #endif 1569 if (sensitive->external_keysign) 1570 ok = ssh_keysign(private, &signature, &slen, 1571 buffer_ptr(&b), buffer_len(&b)); 1572 else 1573 ok = key_sign(private, &signature, &slen, 1574 buffer_ptr(&b), buffer_len(&b)); 1575 key_free(private); 1576 buffer_free(&b); 1577 if (ok != 0) { 1578 error("key_sign failed"); 1579 free(chost); 1580 free(pkalg); 1581 free(blob); 1582 return 0; 1583 } 1584 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1585 packet_put_cstring(authctxt->server_user); 1586 packet_put_cstring(authctxt->service); 1587 packet_put_cstring(authctxt->method->name); 1588 packet_put_cstring(pkalg); 1589 packet_put_string(blob, blen); 1590 packet_put_cstring(chost); 1591 packet_put_cstring(authctxt->local_user); 1592 packet_put_string(signature, slen); 1593 explicit_bzero(signature, slen); 1594 free(signature); 1595 free(chost); 1596 free(pkalg); 1597 free(blob); 1598 1599 packet_send(); 1600 return 1; 1601 } 1602 1603 /* find auth method */ 1604 1605 /* 1606 * given auth method name, if configurable options permit this method fill 1607 * in auth_ident field and return true, otherwise return false. 1608 */ 1609 static int 1610 authmethod_is_enabled(Authmethod *method) 1611 { 1612 if (method == NULL) 1613 return 0; 1614 /* return false if options indicate this method is disabled */ 1615 if (method->enabled == NULL || *method->enabled == 0) 1616 return 0; 1617 /* return false if batch mode is enabled but method needs interactive mode */ 1618 if (method->batch_flag != NULL && *method->batch_flag != 0) 1619 return 0; 1620 return 1; 1621 } 1622 1623 static Authmethod * 1624 authmethod_lookup(const char *name) 1625 { 1626 Authmethod *method = NULL; 1627 if (name != NULL) 1628 for (method = authmethods; method->name != NULL; method++) 1629 if (strcmp(name, method->name) == 0) 1630 return method; 1631 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1632 return NULL; 1633 } 1634 1635 /* XXX internal state */ 1636 static Authmethod *current = NULL; 1637 static char *supported = NULL; 1638 static char *preferred = NULL; 1639 1640 /* 1641 * Given the authentication method list sent by the server, return the 1642 * next method we should try. If the server initially sends a nil list, 1643 * use a built-in default list. 1644 */ 1645 static Authmethod * 1646 authmethod_get(char *authlist) 1647 { 1648 char *name = NULL; 1649 u_int next; 1650 1651 /* Use a suitable default if we're passed a nil list. */ 1652 if (authlist == NULL || strlen(authlist) == 0) 1653 authlist = options.preferred_authentications; 1654 1655 if (supported == NULL || strcmp(authlist, supported) != 0) { 1656 debug3("start over, passed a different list %s", authlist); 1657 free(supported); 1658 supported = xstrdup(authlist); 1659 preferred = options.preferred_authentications; 1660 debug3("preferred %s", preferred); 1661 current = NULL; 1662 } else if (current != NULL && authmethod_is_enabled(current)) 1663 return current; 1664 1665 for (;;) { 1666 if ((name = match_list(preferred, supported, &next)) == NULL) { 1667 debug("No more authentication methods to try."); 1668 current = NULL; 1669 return NULL; 1670 } 1671 preferred += next; 1672 debug3("authmethod_lookup %s", name); 1673 debug3("remaining preferred: %s", preferred); 1674 if ((current = authmethod_lookup(name)) != NULL && 1675 authmethod_is_enabled(current)) { 1676 debug3("authmethod_is_enabled %s", name); 1677 debug("Next authentication method: %s", name); 1678 free(name); 1679 return current; 1680 } 1681 free(name); 1682 } 1683 } 1684 1685 static char * 1686 authmethods_get(void) 1687 { 1688 Authmethod *method = NULL; 1689 Buffer b; 1690 char *list; 1691 1692 buffer_init(&b); 1693 for (method = authmethods; method->name != NULL; method++) { 1694 if (authmethod_is_enabled(method)) { 1695 if (buffer_len(&b) > 0) 1696 buffer_append(&b, ",", 1); 1697 buffer_append(&b, method->name, strlen(method->name)); 1698 } 1699 } 1700 buffer_append(&b, "\0", 1); 1701 list = xstrdup(buffer_ptr(&b)); 1702 buffer_free(&b); 1703 return list; 1704 } 1705 1706