1 /* $OpenBSD: sshconnect2.c,v 1.186 2010/11/29 23:45:51 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 "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <netdb.h> 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdarg.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <unistd.h> 43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) 44 #include <vis.h> 45 #endif 46 47 #include "openbsd-compat/sys-queue.h" 48 49 #include "xmalloc.h" 50 #include "ssh.h" 51 #include "ssh2.h" 52 #include "buffer.h" 53 #include "packet.h" 54 #include "compat.h" 55 #include "cipher.h" 56 #include "key.h" 57 #include "kex.h" 58 #include "myproposal.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "readconf.h" 65 #include "misc.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "schnorr.h" 74 #include "jpake.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 extern Kex *xxx_kex; 85 86 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */ 87 /* if it is set then prevent the switch to the null cipher */ 88 89 extern int tty_flag; 90 91 /* 92 * SSH2 key exchange 93 */ 94 95 u_char *session_id2 = NULL; 96 u_int session_id2_len = 0; 97 98 char *xxx_host; 99 struct sockaddr *xxx_hostaddr; 100 101 Kex *xxx_kex = NULL; 102 103 static int 104 verify_host_key_callback(Key *hostkey) 105 { 106 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 107 fatal("Host key verification failed."); 108 return 0; 109 } 110 111 static char * 112 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 113 { 114 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 115 size_t maxlen; 116 struct hostkeys *hostkeys; 117 int ktype; 118 119 /* Find all hostkeys for this hostname */ 120 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 121 hostkeys = init_hostkeys(); 122 load_hostkeys(hostkeys, hostname, options.user_hostfile2); 123 load_hostkeys(hostkeys, hostname, options.system_hostfile2); 124 load_hostkeys(hostkeys, hostname, options.user_hostfile); 125 load_hostkeys(hostkeys, hostname, options.system_hostfile); 126 127 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 128 maxlen = strlen(avail) + 1; 129 first = xmalloc(maxlen); 130 last = xmalloc(maxlen); 131 *first = *last = '\0'; 132 133 #define ALG_APPEND(to, from) \ 134 do { \ 135 if (*to != '\0') \ 136 strlcat(to, ",", maxlen); \ 137 strlcat(to, from, maxlen); \ 138 } while (0) 139 140 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 141 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 142 fatal("%s: unknown alg %s", __func__, alg); 143 if (lookup_key_in_hostkeys_by_type(hostkeys, 144 key_type_plain(ktype), NULL)) 145 ALG_APPEND(first, alg); 146 else 147 ALG_APPEND(last, alg); 148 } 149 #undef ALG_APPEND 150 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 151 if (*first != '\0') 152 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 153 154 xfree(first); 155 xfree(last); 156 xfree(hostname); 157 xfree(oavail); 158 free_hostkeys(hostkeys); 159 160 return ret; 161 } 162 163 void 164 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 165 { 166 Kex *kex; 167 168 xxx_host = host; 169 xxx_hostaddr = hostaddr; 170 171 if (options.ciphers == (char *)-1) { 172 logit("No valid ciphers for protocol version 2 given, using defaults."); 173 options.ciphers = NULL; 174 } 175 if (options.ciphers != NULL) { 176 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 177 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 178 } 179 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 180 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 181 myproposal[PROPOSAL_ENC_ALGS_STOC] = 182 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 183 if (options.compression) { 184 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 185 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 186 } else { 187 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 188 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 189 } 190 if (options.macs != NULL) { 191 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 192 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 193 } 194 if (options.hostkeyalgorithms != NULL) 195 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 196 options.hostkeyalgorithms; 197 else { 198 /* Prefer algorithms that we already have keys for */ 199 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 200 order_hostkeyalgs(host, hostaddr, port); 201 } 202 if (options.kex_algorithms != NULL) 203 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 204 205 if (options.rekey_limit) 206 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 207 208 /* start key exchange */ 209 kex = kex_setup(myproposal); 210 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 211 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 212 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 213 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 214 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 215 kex->client_version_string=client_version_string; 216 kex->server_version_string=server_version_string; 217 kex->verify_host_key=&verify_host_key_callback; 218 219 xxx_kex = kex; 220 221 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 222 223 if (options.use_roaming && !kex->roaming) { 224 debug("Roaming not allowed by server"); 225 options.use_roaming = 0; 226 } 227 228 session_id2 = kex->session_id; 229 session_id2_len = kex->session_id_len; 230 231 #ifdef DEBUG_KEXDH 232 /* send 1st encrypted/maced/compressed message */ 233 packet_start(SSH2_MSG_IGNORE); 234 packet_put_cstring("markus"); 235 packet_send(); 236 packet_write_wait(); 237 #endif 238 } 239 240 /* 241 * Authenticate user 242 */ 243 244 typedef struct Authctxt Authctxt; 245 typedef struct Authmethod Authmethod; 246 typedef struct identity Identity; 247 typedef struct idlist Idlist; 248 249 struct identity { 250 TAILQ_ENTRY(identity) next; 251 AuthenticationConnection *ac; /* set if agent supports key */ 252 Key *key; /* public/private key */ 253 char *filename; /* comment for agent-only keys */ 254 int tried; 255 int isprivate; /* key points to the private key */ 256 }; 257 TAILQ_HEAD(idlist, identity); 258 259 struct Authctxt { 260 const char *server_user; 261 const char *local_user; 262 const char *host; 263 const char *service; 264 Authmethod *method; 265 sig_atomic_t success; 266 char *authlist; 267 /* pubkey */ 268 Idlist keys; 269 AuthenticationConnection *agent; 270 /* hostbased */ 271 Sensitive *sensitive; 272 /* kbd-interactive */ 273 int info_req_seen; 274 /* generic */ 275 void *methoddata; 276 }; 277 struct Authmethod { 278 char *name; /* string to compare against server's list */ 279 int (*userauth)(Authctxt *authctxt); 280 void (*cleanup)(Authctxt *authctxt); 281 int *enabled; /* flag in option struct that enables method */ 282 int *batch_flag; /* flag in option struct that disables method */ 283 }; 284 285 void input_userauth_success(int, u_int32_t, void *); 286 void input_userauth_success_unexpected(int, u_int32_t, void *); 287 void input_userauth_failure(int, u_int32_t, void *); 288 void input_userauth_banner(int, u_int32_t, void *); 289 void input_userauth_error(int, u_int32_t, void *); 290 void input_userauth_info_req(int, u_int32_t, void *); 291 void input_userauth_pk_ok(int, u_int32_t, void *); 292 void input_userauth_passwd_changereq(int, u_int32_t, void *); 293 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 294 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 295 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 296 297 int userauth_none(Authctxt *); 298 int userauth_pubkey(Authctxt *); 299 int userauth_passwd(Authctxt *); 300 int userauth_kbdint(Authctxt *); 301 int userauth_hostbased(Authctxt *); 302 int userauth_jpake(Authctxt *); 303 304 void userauth_jpake_cleanup(Authctxt *); 305 306 #ifdef GSSAPI 307 int userauth_gssapi(Authctxt *authctxt); 308 void input_gssapi_response(int type, u_int32_t, void *); 309 void input_gssapi_token(int type, u_int32_t, void *); 310 void input_gssapi_hash(int type, u_int32_t, void *); 311 void input_gssapi_error(int, u_int32_t, void *); 312 void input_gssapi_errtok(int, u_int32_t, void *); 313 #endif 314 315 void userauth(Authctxt *, char *); 316 317 static int sign_and_send_pubkey(Authctxt *, Identity *); 318 static void pubkey_prepare(Authctxt *); 319 static void pubkey_cleanup(Authctxt *); 320 static Key *load_identity_file(char *); 321 322 static Authmethod *authmethod_get(char *authlist); 323 static Authmethod *authmethod_lookup(const char *name); 324 static char *authmethods_get(void); 325 326 Authmethod authmethods[] = { 327 #ifdef GSSAPI 328 {"gssapi-with-mic", 329 userauth_gssapi, 330 NULL, 331 &options.gss_authentication, 332 NULL}, 333 #endif 334 {"hostbased", 335 userauth_hostbased, 336 NULL, 337 &options.hostbased_authentication, 338 NULL}, 339 {"publickey", 340 userauth_pubkey, 341 NULL, 342 &options.pubkey_authentication, 343 NULL}, 344 #ifdef JPAKE 345 {"jpake-01@openssh.com", 346 userauth_jpake, 347 userauth_jpake_cleanup, 348 &options.zero_knowledge_password_authentication, 349 &options.batch_mode}, 350 #endif 351 {"keyboard-interactive", 352 userauth_kbdint, 353 NULL, 354 &options.kbd_interactive_authentication, 355 &options.batch_mode}, 356 {"password", 357 userauth_passwd, 358 NULL, 359 &options.password_authentication, 360 &options.batch_mode}, 361 {"none", 362 userauth_none, 363 NULL, 364 NULL, 365 NULL}, 366 {NULL, NULL, NULL, NULL, NULL} 367 }; 368 369 void 370 ssh_userauth2(const char *local_user, const char *server_user, char *host, 371 Sensitive *sensitive) 372 { 373 Authctxt authctxt; 374 int type; 375 376 if (options.challenge_response_authentication) 377 options.kbd_interactive_authentication = 1; 378 379 packet_start(SSH2_MSG_SERVICE_REQUEST); 380 packet_put_cstring("ssh-userauth"); 381 packet_send(); 382 debug("SSH2_MSG_SERVICE_REQUEST sent"); 383 packet_write_wait(); 384 type = packet_read(); 385 if (type != SSH2_MSG_SERVICE_ACCEPT) 386 fatal("Server denied authentication request: %d", type); 387 if (packet_remaining() > 0) { 388 char *reply = packet_get_string(NULL); 389 debug2("service_accept: %s", reply); 390 xfree(reply); 391 } else { 392 debug2("buggy server: service_accept w/o service"); 393 } 394 packet_check_eom(); 395 debug("SSH2_MSG_SERVICE_ACCEPT received"); 396 397 if (options.preferred_authentications == NULL) 398 options.preferred_authentications = authmethods_get(); 399 400 /* setup authentication context */ 401 memset(&authctxt, 0, sizeof(authctxt)); 402 pubkey_prepare(&authctxt); 403 authctxt.server_user = server_user; 404 authctxt.local_user = local_user; 405 authctxt.host = host; 406 authctxt.service = "ssh-connection"; /* service name */ 407 authctxt.success = 0; 408 authctxt.method = authmethod_lookup("none"); 409 authctxt.authlist = NULL; 410 authctxt.methoddata = NULL; 411 authctxt.sensitive = sensitive; 412 authctxt.info_req_seen = 0; 413 if (authctxt.method == NULL) 414 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 415 416 /* initial userauth request */ 417 userauth_none(&authctxt); 418 419 dispatch_init(&input_userauth_error); 420 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 421 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 422 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 423 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 424 425 pubkey_cleanup(&authctxt); 426 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 427 428 /* if the user wants to use the none cipher do it */ 429 /* post authentication and only if the right conditions are met */ 430 /* both of the NONE commands must be true and there must be no */ 431 /* tty allocated */ 432 if ((options.none_switch == 1) && (options.none_enabled == 1)) 433 { 434 if (!tty_flag) /* no null on tty sessions */ 435 { 436 debug("Requesting none rekeying..."); 437 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none"; 438 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none"; 439 kex_prop2buf(&xxx_kex->my,myproposal); 440 packet_request_rekeying(); 441 fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n"); 442 } 443 else 444 { 445 /* requested NONE cipher when in a tty */ 446 debug("Cannot switch to NONE cipher with tty allocated"); 447 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 448 } 449 } 450 debug("Authentication succeeded (%s).", authctxt.method->name); 451 } 452 453 void 454 userauth(Authctxt *authctxt, char *authlist) 455 { 456 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 457 authctxt->method->cleanup(authctxt); 458 459 if (authctxt->methoddata) { 460 xfree(authctxt->methoddata); 461 authctxt->methoddata = NULL; 462 } 463 if (authlist == NULL) { 464 authlist = authctxt->authlist; 465 } else { 466 if (authctxt->authlist) 467 xfree(authctxt->authlist); 468 authctxt->authlist = authlist; 469 } 470 for (;;) { 471 Authmethod *method = authmethod_get(authlist); 472 if (method == NULL) 473 fatal("Permission denied (%s).", authlist); 474 authctxt->method = method; 475 476 /* reset the per method handler */ 477 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 478 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 479 480 /* and try new method */ 481 if (method->userauth(authctxt) != 0) { 482 debug2("we sent a %s packet, wait for reply", method->name); 483 break; 484 } else { 485 debug2("we did not send a packet, disable method"); 486 method->enabled = NULL; 487 } 488 } 489 } 490 491 /* ARGSUSED */ 492 void 493 input_userauth_error(int type, u_int32_t seq, void *ctxt) 494 { 495 fatal("input_userauth_error: bad message during authentication: " 496 "type %d", type); 497 } 498 499 /* ARGSUSED */ 500 void 501 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 502 { 503 char *msg, *raw, *lang; 504 u_int len; 505 506 debug3("input_userauth_banner"); 507 raw = packet_get_string(&len); 508 lang = packet_get_string(NULL); 509 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 510 if (len > 65536) 511 len = 65536; 512 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 513 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 514 fprintf(stderr, "%s", msg); 515 xfree(msg); 516 } 517 xfree(raw); 518 xfree(lang); 519 } 520 521 /* ARGSUSED */ 522 void 523 input_userauth_success(int type, u_int32_t seq, void *ctxt) 524 { 525 Authctxt *authctxt = ctxt; 526 527 if (authctxt == NULL) 528 fatal("input_userauth_success: no authentication context"); 529 if (authctxt->authlist) { 530 xfree(authctxt->authlist); 531 authctxt->authlist = NULL; 532 } 533 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 534 authctxt->method->cleanup(authctxt); 535 if (authctxt->methoddata) { 536 xfree(authctxt->methoddata); 537 authctxt->methoddata = NULL; 538 } 539 authctxt->success = 1; /* break out */ 540 } 541 542 void 543 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 544 { 545 Authctxt *authctxt = ctxt; 546 547 if (authctxt == NULL) 548 fatal("%s: no authentication context", __func__); 549 550 fatal("Unexpected authentication success during %s.", 551 authctxt->method->name); 552 } 553 554 /* ARGSUSED */ 555 void 556 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 557 { 558 Authctxt *authctxt = ctxt; 559 char *authlist = NULL; 560 int partial; 561 562 if (authctxt == NULL) 563 fatal("input_userauth_failure: no authentication context"); 564 565 authlist = packet_get_string(NULL); 566 partial = packet_get_char(); 567 packet_check_eom(); 568 569 if (partial != 0) 570 logit("Authenticated with partial success."); 571 debug("Authentications that can continue: %s", authlist); 572 573 userauth(authctxt, authlist); 574 } 575 576 /* ARGSUSED */ 577 void 578 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 579 { 580 Authctxt *authctxt = ctxt; 581 Key *key = NULL; 582 Identity *id = NULL; 583 Buffer b; 584 int pktype, sent = 0; 585 u_int alen, blen; 586 char *pkalg, *fp; 587 u_char *pkblob; 588 589 if (authctxt == NULL) 590 fatal("input_userauth_pk_ok: no authentication context"); 591 if (datafellows & SSH_BUG_PKOK) { 592 /* this is similar to SSH_BUG_PKAUTH */ 593 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 594 pkblob = packet_get_string(&blen); 595 buffer_init(&b); 596 buffer_append(&b, pkblob, blen); 597 pkalg = buffer_get_string(&b, &alen); 598 buffer_free(&b); 599 } else { 600 pkalg = packet_get_string(&alen); 601 pkblob = packet_get_string(&blen); 602 } 603 packet_check_eom(); 604 605 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 606 607 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 608 debug("unknown pkalg %s", pkalg); 609 goto done; 610 } 611 if ((key = key_from_blob(pkblob, blen)) == NULL) { 612 debug("no key from blob. pkalg %s", pkalg); 613 goto done; 614 } 615 if (key->type != pktype) { 616 error("input_userauth_pk_ok: type mismatch " 617 "for decoded key (received %d, expected %d)", 618 key->type, pktype); 619 goto done; 620 } 621 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 622 debug2("input_userauth_pk_ok: fp %s", fp); 623 xfree(fp); 624 625 /* 626 * search keys in the reverse order, because last candidate has been 627 * moved to the end of the queue. this also avoids confusion by 628 * duplicate keys 629 */ 630 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 631 if (key_equal(key, id->key)) { 632 sent = sign_and_send_pubkey(authctxt, id); 633 break; 634 } 635 } 636 done: 637 if (key != NULL) 638 key_free(key); 639 xfree(pkalg); 640 xfree(pkblob); 641 642 /* try another method if we did not send a packet */ 643 if (sent == 0) 644 userauth(authctxt, NULL); 645 } 646 647 #ifdef GSSAPI 648 int 649 userauth_gssapi(Authctxt *authctxt) 650 { 651 Gssctxt *gssctxt = NULL; 652 static gss_OID_set gss_supported = NULL; 653 static u_int mech = 0; 654 OM_uint32 min; 655 int ok = 0; 656 657 /* Try one GSSAPI method at a time, rather than sending them all at 658 * once. */ 659 660 if (gss_supported == NULL) 661 gss_indicate_mechs(&min, &gss_supported); 662 663 /* Check to see if the mechanism is usable before we offer it */ 664 while (mech < gss_supported->count && !ok) { 665 /* My DER encoding requires length<128 */ 666 if (gss_supported->elements[mech].length < 128 && 667 ssh_gssapi_check_mechanism(&gssctxt, 668 &gss_supported->elements[mech], authctxt->host)) { 669 ok = 1; /* Mechanism works */ 670 } else { 671 mech++; 672 } 673 } 674 675 if (!ok) 676 return 0; 677 678 authctxt->methoddata=(void *)gssctxt; 679 680 packet_start(SSH2_MSG_USERAUTH_REQUEST); 681 packet_put_cstring(authctxt->server_user); 682 packet_put_cstring(authctxt->service); 683 packet_put_cstring(authctxt->method->name); 684 685 packet_put_int(1); 686 687 packet_put_int((gss_supported->elements[mech].length) + 2); 688 packet_put_char(SSH_GSS_OIDTYPE); 689 packet_put_char(gss_supported->elements[mech].length); 690 packet_put_raw(gss_supported->elements[mech].elements, 691 gss_supported->elements[mech].length); 692 693 packet_send(); 694 695 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 696 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 697 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 698 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 699 700 mech++; /* Move along to next candidate */ 701 702 return 1; 703 } 704 705 static OM_uint32 706 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 707 { 708 Authctxt *authctxt = ctxt; 709 Gssctxt *gssctxt = authctxt->methoddata; 710 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 711 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 712 gss_buffer_desc gssbuf; 713 OM_uint32 status, ms, flags; 714 Buffer b; 715 716 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 717 recv_tok, &send_tok, &flags); 718 719 if (send_tok.length > 0) { 720 if (GSS_ERROR(status)) 721 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 722 else 723 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 724 725 packet_put_string(send_tok.value, send_tok.length); 726 packet_send(); 727 gss_release_buffer(&ms, &send_tok); 728 } 729 730 if (status == GSS_S_COMPLETE) { 731 /* send either complete or MIC, depending on mechanism */ 732 if (!(flags & GSS_C_INTEG_FLAG)) { 733 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 734 packet_send(); 735 } else { 736 ssh_gssapi_buildmic(&b, authctxt->server_user, 737 authctxt->service, "gssapi-with-mic"); 738 739 gssbuf.value = buffer_ptr(&b); 740 gssbuf.length = buffer_len(&b); 741 742 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 743 744 if (!GSS_ERROR(status)) { 745 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 746 packet_put_string(mic.value, mic.length); 747 748 packet_send(); 749 } 750 751 buffer_free(&b); 752 gss_release_buffer(&ms, &mic); 753 } 754 } 755 756 return status; 757 } 758 759 /* ARGSUSED */ 760 void 761 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 762 { 763 Authctxt *authctxt = ctxt; 764 Gssctxt *gssctxt; 765 int oidlen; 766 char *oidv; 767 768 if (authctxt == NULL) 769 fatal("input_gssapi_response: no authentication context"); 770 gssctxt = authctxt->methoddata; 771 772 /* Setup our OID */ 773 oidv = packet_get_string(&oidlen); 774 775 if (oidlen <= 2 || 776 oidv[0] != SSH_GSS_OIDTYPE || 777 oidv[1] != oidlen - 2) { 778 xfree(oidv); 779 debug("Badly encoded mechanism OID received"); 780 userauth(authctxt, NULL); 781 return; 782 } 783 784 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 785 fatal("Server returned different OID than expected"); 786 787 packet_check_eom(); 788 789 xfree(oidv); 790 791 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 792 /* Start again with next method on list */ 793 debug("Trying to start again"); 794 userauth(authctxt, NULL); 795 return; 796 } 797 } 798 799 /* ARGSUSED */ 800 void 801 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 802 { 803 Authctxt *authctxt = ctxt; 804 gss_buffer_desc recv_tok; 805 OM_uint32 status; 806 u_int slen; 807 808 if (authctxt == NULL) 809 fatal("input_gssapi_response: no authentication context"); 810 811 recv_tok.value = packet_get_string(&slen); 812 recv_tok.length = slen; /* safe typecast */ 813 814 packet_check_eom(); 815 816 status = process_gssapi_token(ctxt, &recv_tok); 817 818 xfree(recv_tok.value); 819 820 if (GSS_ERROR(status)) { 821 /* Start again with the next method in the list */ 822 userauth(authctxt, NULL); 823 return; 824 } 825 } 826 827 /* ARGSUSED */ 828 void 829 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 830 { 831 Authctxt *authctxt = ctxt; 832 Gssctxt *gssctxt; 833 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 834 gss_buffer_desc recv_tok; 835 OM_uint32 status, ms; 836 u_int len; 837 838 if (authctxt == NULL) 839 fatal("input_gssapi_response: no authentication context"); 840 gssctxt = authctxt->methoddata; 841 842 recv_tok.value = packet_get_string(&len); 843 recv_tok.length = len; 844 845 packet_check_eom(); 846 847 /* Stick it into GSSAPI and see what it says */ 848 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 849 &recv_tok, &send_tok, NULL); 850 851 xfree(recv_tok.value); 852 gss_release_buffer(&ms, &send_tok); 853 854 /* Server will be returning a failed packet after this one */ 855 } 856 857 /* ARGSUSED */ 858 void 859 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 860 { 861 OM_uint32 maj, min; 862 char *msg; 863 char *lang; 864 865 maj=packet_get_int(); 866 min=packet_get_int(); 867 msg=packet_get_string(NULL); 868 lang=packet_get_string(NULL); 869 870 packet_check_eom(); 871 872 debug("Server GSSAPI Error:\n%s", msg); 873 xfree(msg); 874 xfree(lang); 875 } 876 #endif /* GSSAPI */ 877 878 int 879 userauth_none(Authctxt *authctxt) 880 { 881 /* initial userauth request */ 882 packet_start(SSH2_MSG_USERAUTH_REQUEST); 883 packet_put_cstring(authctxt->server_user); 884 packet_put_cstring(authctxt->service); 885 packet_put_cstring(authctxt->method->name); 886 packet_send(); 887 return 1; 888 } 889 890 int 891 userauth_passwd(Authctxt *authctxt) 892 { 893 static int attempt = 0; 894 char prompt[150]; 895 char *password; 896 const char *host = options.host_key_alias ? options.host_key_alias : 897 authctxt->host; 898 899 if (attempt++ >= options.number_of_password_prompts) 900 return 0; 901 902 if (attempt != 1) 903 error("Permission denied, please try again."); 904 905 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 906 authctxt->server_user, host); 907 password = read_passphrase(prompt, 0); 908 packet_start(SSH2_MSG_USERAUTH_REQUEST); 909 packet_put_cstring(authctxt->server_user); 910 packet_put_cstring(authctxt->service); 911 packet_put_cstring(authctxt->method->name); 912 packet_put_char(0); 913 packet_put_cstring(password); 914 memset(password, 0, strlen(password)); 915 xfree(password); 916 packet_add_padding(64); 917 packet_send(); 918 919 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 920 &input_userauth_passwd_changereq); 921 922 return 1; 923 } 924 925 /* 926 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 927 */ 928 /* ARGSUSED */ 929 void 930 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 931 { 932 Authctxt *authctxt = ctxt; 933 char *info, *lang, *password = NULL, *retype = NULL; 934 char prompt[150]; 935 const char *host = options.host_key_alias ? options.host_key_alias : 936 authctxt->host; 937 938 debug2("input_userauth_passwd_changereq"); 939 940 if (authctxt == NULL) 941 fatal("input_userauth_passwd_changereq: " 942 "no authentication context"); 943 944 info = packet_get_string(NULL); 945 lang = packet_get_string(NULL); 946 if (strlen(info) > 0) 947 logit("%s", info); 948 xfree(info); 949 xfree(lang); 950 packet_start(SSH2_MSG_USERAUTH_REQUEST); 951 packet_put_cstring(authctxt->server_user); 952 packet_put_cstring(authctxt->service); 953 packet_put_cstring(authctxt->method->name); 954 packet_put_char(1); /* additional info */ 955 snprintf(prompt, sizeof(prompt), 956 "Enter %.30s@%.128s's old password: ", 957 authctxt->server_user, host); 958 password = read_passphrase(prompt, 0); 959 packet_put_cstring(password); 960 memset(password, 0, strlen(password)); 961 xfree(password); 962 password = NULL; 963 while (password == NULL) { 964 snprintf(prompt, sizeof(prompt), 965 "Enter %.30s@%.128s's new password: ", 966 authctxt->server_user, host); 967 password = read_passphrase(prompt, RP_ALLOW_EOF); 968 if (password == NULL) { 969 /* bail out */ 970 return; 971 } 972 snprintf(prompt, sizeof(prompt), 973 "Retype %.30s@%.128s's new password: ", 974 authctxt->server_user, host); 975 retype = read_passphrase(prompt, 0); 976 if (strcmp(password, retype) != 0) { 977 memset(password, 0, strlen(password)); 978 xfree(password); 979 logit("Mismatch; try again, EOF to quit."); 980 password = NULL; 981 } 982 memset(retype, 0, strlen(retype)); 983 xfree(retype); 984 } 985 packet_put_cstring(password); 986 memset(password, 0, strlen(password)); 987 xfree(password); 988 packet_add_padding(64); 989 packet_send(); 990 991 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 992 &input_userauth_passwd_changereq); 993 } 994 995 #ifdef JPAKE 996 static char * 997 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 998 { 999 /* OpenBSD crypt(3) handles all of these */ 1000 if (strcmp(crypt_scheme, "crypt") == 0 || 1001 strcmp(crypt_scheme, "bcrypt") == 0 || 1002 strcmp(crypt_scheme, "md5crypt") == 0 || 1003 strcmp(crypt_scheme, "crypt-extended") == 0) 1004 return xstrdup(crypt(password, salt)); 1005 error("%s: unsupported password encryption scheme \"%.100s\"", 1006 __func__, crypt_scheme); 1007 return NULL; 1008 } 1009 1010 static BIGNUM * 1011 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 1012 const char *salt) 1013 { 1014 char prompt[256], *password, *crypted; 1015 u_char *secret; 1016 u_int secret_len; 1017 BIGNUM *ret; 1018 1019 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 1020 authctxt->server_user, authctxt->host); 1021 password = read_passphrase(prompt, 0); 1022 1023 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 1024 logit("Disabling %s authentication", authctxt->method->name); 1025 authctxt->method->enabled = NULL; 1026 /* Continue with an empty password to fail gracefully */ 1027 crypted = xstrdup(""); 1028 } 1029 1030 #ifdef JPAKE_DEBUG 1031 debug3("%s: salt = %s", __func__, salt); 1032 debug3("%s: scheme = %s", __func__, crypt_scheme); 1033 debug3("%s: crypted = %s", __func__, crypted); 1034 #endif 1035 1036 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 1037 &secret, &secret_len) != 0) 1038 fatal("%s: hash_buffer", __func__); 1039 1040 bzero(password, strlen(password)); 1041 bzero(crypted, strlen(crypted)); 1042 xfree(password); 1043 xfree(crypted); 1044 1045 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1046 fatal("%s: BN_bin2bn (secret)", __func__); 1047 bzero(secret, secret_len); 1048 xfree(secret); 1049 1050 return ret; 1051 } 1052 1053 /* ARGSUSED */ 1054 void 1055 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1056 { 1057 Authctxt *authctxt = ctxt; 1058 struct jpake_ctx *pctx = authctxt->methoddata; 1059 u_char *x3_proof, *x4_proof, *x2_s_proof; 1060 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1061 char *crypt_scheme, *salt; 1062 1063 /* Disable this message */ 1064 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1065 1066 if ((pctx->g_x3 = BN_new()) == NULL || 1067 (pctx->g_x4 = BN_new()) == NULL) 1068 fatal("%s: BN_new", __func__); 1069 1070 /* Fetch step 1 values */ 1071 crypt_scheme = packet_get_string(NULL); 1072 salt = packet_get_string(NULL); 1073 pctx->server_id = packet_get_string(&pctx->server_id_len); 1074 packet_get_bignum2(pctx->g_x3); 1075 packet_get_bignum2(pctx->g_x4); 1076 x3_proof = packet_get_string(&x3_proof_len); 1077 x4_proof = packet_get_string(&x4_proof_len); 1078 packet_check_eom(); 1079 1080 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1081 1082 /* Obtain password and derive secret */ 1083 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1084 bzero(crypt_scheme, strlen(crypt_scheme)); 1085 bzero(salt, strlen(salt)); 1086 xfree(crypt_scheme); 1087 xfree(salt); 1088 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1089 1090 /* Calculate step 2 values */ 1091 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1092 pctx->g_x3, pctx->g_x4, pctx->x2, 1093 pctx->server_id, pctx->server_id_len, 1094 pctx->client_id, pctx->client_id_len, 1095 x3_proof, x3_proof_len, 1096 x4_proof, x4_proof_len, 1097 &pctx->a, 1098 &x2_s_proof, &x2_s_proof_len); 1099 1100 bzero(x3_proof, x3_proof_len); 1101 bzero(x4_proof, x4_proof_len); 1102 xfree(x3_proof); 1103 xfree(x4_proof); 1104 1105 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1106 1107 /* Send values for step 2 */ 1108 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1109 packet_put_bignum2(pctx->a); 1110 packet_put_string(x2_s_proof, x2_s_proof_len); 1111 packet_send(); 1112 1113 bzero(x2_s_proof, x2_s_proof_len); 1114 xfree(x2_s_proof); 1115 1116 /* Expect step 2 packet from peer */ 1117 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1118 input_userauth_jpake_server_step2); 1119 } 1120 1121 /* ARGSUSED */ 1122 void 1123 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1124 { 1125 Authctxt *authctxt = ctxt; 1126 struct jpake_ctx *pctx = authctxt->methoddata; 1127 u_char *x4_s_proof; 1128 u_int x4_s_proof_len; 1129 1130 /* Disable this message */ 1131 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1132 1133 if ((pctx->b = BN_new()) == NULL) 1134 fatal("%s: BN_new", __func__); 1135 1136 /* Fetch step 2 values */ 1137 packet_get_bignum2(pctx->b); 1138 x4_s_proof = packet_get_string(&x4_s_proof_len); 1139 packet_check_eom(); 1140 1141 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1142 1143 /* Derive shared key and calculate confirmation hash */ 1144 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1145 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1146 pctx->client_id, pctx->client_id_len, 1147 pctx->server_id, pctx->server_id_len, 1148 session_id2, session_id2_len, 1149 x4_s_proof, x4_s_proof_len, 1150 &pctx->k, 1151 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1152 1153 bzero(x4_s_proof, x4_s_proof_len); 1154 xfree(x4_s_proof); 1155 1156 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1157 1158 /* Send key confirmation proof */ 1159 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1160 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1161 packet_send(); 1162 1163 /* Expect confirmation from peer */ 1164 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1165 input_userauth_jpake_server_confirm); 1166 } 1167 1168 /* ARGSUSED */ 1169 void 1170 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1171 { 1172 Authctxt *authctxt = ctxt; 1173 struct jpake_ctx *pctx = authctxt->methoddata; 1174 1175 /* Disable this message */ 1176 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1177 1178 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1179 packet_check_eom(); 1180 1181 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1182 1183 /* Verify expected confirmation hash */ 1184 if (jpake_check_confirm(pctx->k, 1185 pctx->server_id, pctx->server_id_len, 1186 session_id2, session_id2_len, 1187 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1188 debug("%s: %s success", __func__, authctxt->method->name); 1189 else { 1190 debug("%s: confirmation mismatch", __func__); 1191 /* XXX stash this so if auth succeeds then we can warn/kill */ 1192 } 1193 1194 userauth_jpake_cleanup(authctxt); 1195 } 1196 #endif /* JPAKE */ 1197 1198 static int 1199 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1200 u_char *data, u_int datalen) 1201 { 1202 Key *prv; 1203 int ret; 1204 1205 /* the agent supports this key */ 1206 if (id->ac) 1207 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1208 data, datalen)); 1209 /* 1210 * we have already loaded the private key or 1211 * the private key is stored in external hardware 1212 */ 1213 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1214 return (key_sign(id->key, sigp, lenp, data, datalen)); 1215 /* load the private key from the file */ 1216 if ((prv = load_identity_file(id->filename)) == NULL) 1217 return (-1); 1218 ret = key_sign(prv, sigp, lenp, data, datalen); 1219 key_free(prv); 1220 return (ret); 1221 } 1222 1223 static int 1224 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1225 { 1226 Buffer b; 1227 u_char *blob, *signature; 1228 u_int bloblen, slen; 1229 u_int skip = 0; 1230 int ret = -1; 1231 int have_sig = 1; 1232 char *fp; 1233 1234 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1235 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1236 xfree(fp); 1237 1238 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1239 /* we cannot handle this key */ 1240 debug3("sign_and_send_pubkey: cannot handle key"); 1241 return 0; 1242 } 1243 /* data to be signed */ 1244 buffer_init(&b); 1245 if (datafellows & SSH_OLD_SESSIONID) { 1246 buffer_append(&b, session_id2, session_id2_len); 1247 skip = session_id2_len; 1248 } else { 1249 buffer_put_string(&b, session_id2, session_id2_len); 1250 skip = buffer_len(&b); 1251 } 1252 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1253 buffer_put_cstring(&b, authctxt->server_user); 1254 buffer_put_cstring(&b, 1255 datafellows & SSH_BUG_PKSERVICE ? 1256 "ssh-userauth" : 1257 authctxt->service); 1258 if (datafellows & SSH_BUG_PKAUTH) { 1259 buffer_put_char(&b, have_sig); 1260 } else { 1261 buffer_put_cstring(&b, authctxt->method->name); 1262 buffer_put_char(&b, have_sig); 1263 buffer_put_cstring(&b, key_ssh_name(id->key)); 1264 } 1265 buffer_put_string(&b, blob, bloblen); 1266 1267 /* generate signature */ 1268 ret = identity_sign(id, &signature, &slen, 1269 buffer_ptr(&b), buffer_len(&b)); 1270 if (ret == -1) { 1271 xfree(blob); 1272 buffer_free(&b); 1273 return 0; 1274 } 1275 #ifdef DEBUG_PK 1276 buffer_dump(&b); 1277 #endif 1278 if (datafellows & SSH_BUG_PKSERVICE) { 1279 buffer_clear(&b); 1280 buffer_append(&b, session_id2, session_id2_len); 1281 skip = session_id2_len; 1282 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1283 buffer_put_cstring(&b, authctxt->server_user); 1284 buffer_put_cstring(&b, authctxt->service); 1285 buffer_put_cstring(&b, authctxt->method->name); 1286 buffer_put_char(&b, have_sig); 1287 if (!(datafellows & SSH_BUG_PKAUTH)) 1288 buffer_put_cstring(&b, key_ssh_name(id->key)); 1289 buffer_put_string(&b, blob, bloblen); 1290 } 1291 xfree(blob); 1292 1293 /* append signature */ 1294 buffer_put_string(&b, signature, slen); 1295 xfree(signature); 1296 1297 /* skip session id and packet type */ 1298 if (buffer_len(&b) < skip + 1) 1299 fatal("userauth_pubkey: internal error"); 1300 buffer_consume(&b, skip + 1); 1301 1302 /* put remaining data from buffer into packet */ 1303 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1304 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1305 buffer_free(&b); 1306 packet_send(); 1307 1308 return 1; 1309 } 1310 1311 static int 1312 send_pubkey_test(Authctxt *authctxt, Identity *id) 1313 { 1314 u_char *blob; 1315 u_int bloblen, have_sig = 0; 1316 1317 debug3("send_pubkey_test"); 1318 1319 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1320 /* we cannot handle this key */ 1321 debug3("send_pubkey_test: cannot handle key"); 1322 return 0; 1323 } 1324 /* register callback for USERAUTH_PK_OK message */ 1325 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1326 1327 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1328 packet_put_cstring(authctxt->server_user); 1329 packet_put_cstring(authctxt->service); 1330 packet_put_cstring(authctxt->method->name); 1331 packet_put_char(have_sig); 1332 if (!(datafellows & SSH_BUG_PKAUTH)) 1333 packet_put_cstring(key_ssh_name(id->key)); 1334 packet_put_string(blob, bloblen); 1335 xfree(blob); 1336 packet_send(); 1337 return 1; 1338 } 1339 1340 static Key * 1341 load_identity_file(char *filename) 1342 { 1343 Key *private; 1344 char prompt[300], *passphrase; 1345 int perm_ok = 0, quit, i; 1346 struct stat st; 1347 1348 if (stat(filename, &st) < 0) { 1349 debug3("no such identity: %s", filename); 1350 return NULL; 1351 } 1352 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1353 if (!perm_ok) 1354 return NULL; 1355 if (private == NULL) { 1356 if (options.batch_mode) 1357 return NULL; 1358 snprintf(prompt, sizeof prompt, 1359 "Enter passphrase for key '%.100s': ", filename); 1360 for (i = 0; i < options.number_of_password_prompts; i++) { 1361 passphrase = read_passphrase(prompt, 0); 1362 if (strcmp(passphrase, "") != 0) { 1363 private = key_load_private_type(KEY_UNSPEC, 1364 filename, passphrase, NULL, NULL); 1365 quit = 0; 1366 } else { 1367 debug2("no passphrase given, try next key"); 1368 quit = 1; 1369 } 1370 memset(passphrase, 0, strlen(passphrase)); 1371 xfree(passphrase); 1372 if (private != NULL || quit) 1373 break; 1374 debug2("bad passphrase given, try again..."); 1375 } 1376 } 1377 return private; 1378 } 1379 1380 /* 1381 * try keys in the following order: 1382 * 1. agent keys that are found in the config file 1383 * 2. other agent keys 1384 * 3. keys that are only listed in the config file 1385 */ 1386 static void 1387 pubkey_prepare(Authctxt *authctxt) 1388 { 1389 Identity *id; 1390 Idlist agent, files, *preferred; 1391 Key *key; 1392 AuthenticationConnection *ac; 1393 char *comment; 1394 int i, found; 1395 1396 TAILQ_INIT(&agent); /* keys from the agent */ 1397 TAILQ_INIT(&files); /* keys from the config file */ 1398 preferred = &authctxt->keys; 1399 TAILQ_INIT(preferred); /* preferred order of keys */ 1400 1401 /* list of keys stored in the filesystem */ 1402 for (i = 0; i < options.num_identity_files; i++) { 1403 key = options.identity_keys[i]; 1404 if (key && key->type == KEY_RSA1) 1405 continue; 1406 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1407 continue; 1408 options.identity_keys[i] = NULL; 1409 id = xcalloc(1, sizeof(*id)); 1410 id->key = key; 1411 id->filename = xstrdup(options.identity_files[i]); 1412 TAILQ_INSERT_TAIL(&files, id, next); 1413 } 1414 /* list of keys supported by the agent */ 1415 if ((ac = ssh_get_authentication_connection())) { 1416 for (key = ssh_get_first_identity(ac, &comment, 2); 1417 key != NULL; 1418 key = ssh_get_next_identity(ac, &comment, 2)) { 1419 found = 0; 1420 TAILQ_FOREACH(id, &files, next) { 1421 /* agent keys from the config file are preferred */ 1422 if (key_equal(key, id->key)) { 1423 key_free(key); 1424 xfree(comment); 1425 TAILQ_REMOVE(&files, id, next); 1426 TAILQ_INSERT_TAIL(preferred, id, next); 1427 id->ac = ac; 1428 found = 1; 1429 break; 1430 } 1431 } 1432 if (!found && !options.identities_only) { 1433 id = xcalloc(1, sizeof(*id)); 1434 id->key = key; 1435 id->filename = comment; 1436 id->ac = ac; 1437 TAILQ_INSERT_TAIL(&agent, id, next); 1438 } 1439 } 1440 /* append remaining agent keys */ 1441 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1442 TAILQ_REMOVE(&agent, id, next); 1443 TAILQ_INSERT_TAIL(preferred, id, next); 1444 } 1445 authctxt->agent = ac; 1446 } 1447 /* append remaining keys from the config file */ 1448 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1449 TAILQ_REMOVE(&files, id, next); 1450 TAILQ_INSERT_TAIL(preferred, id, next); 1451 } 1452 TAILQ_FOREACH(id, preferred, next) { 1453 debug2("key: %s (%p)", id->filename, id->key); 1454 } 1455 } 1456 1457 static void 1458 pubkey_cleanup(Authctxt *authctxt) 1459 { 1460 Identity *id; 1461 1462 if (authctxt->agent != NULL) 1463 ssh_close_authentication_connection(authctxt->agent); 1464 for (id = TAILQ_FIRST(&authctxt->keys); id; 1465 id = TAILQ_FIRST(&authctxt->keys)) { 1466 TAILQ_REMOVE(&authctxt->keys, id, next); 1467 if (id->key) 1468 key_free(id->key); 1469 if (id->filename) 1470 xfree(id->filename); 1471 xfree(id); 1472 } 1473 } 1474 1475 int 1476 userauth_pubkey(Authctxt *authctxt) 1477 { 1478 Identity *id; 1479 int sent = 0; 1480 1481 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1482 if (id->tried++) 1483 return (0); 1484 /* move key to the end of the queue */ 1485 TAILQ_REMOVE(&authctxt->keys, id, next); 1486 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1487 /* 1488 * send a test message if we have the public key. for 1489 * encrypted keys we cannot do this and have to load the 1490 * private key instead 1491 */ 1492 if (id->key && id->key->type != KEY_RSA1) { 1493 debug("Offering %s public key: %s", key_type(id->key), 1494 id->filename); 1495 sent = send_pubkey_test(authctxt, id); 1496 } else if (id->key == NULL) { 1497 debug("Trying private key: %s", id->filename); 1498 id->key = load_identity_file(id->filename); 1499 if (id->key != NULL) { 1500 id->isprivate = 1; 1501 sent = sign_and_send_pubkey(authctxt, id); 1502 key_free(id->key); 1503 id->key = NULL; 1504 } 1505 } 1506 if (sent) 1507 return (sent); 1508 } 1509 return (0); 1510 } 1511 1512 /* 1513 * Send userauth request message specifying keyboard-interactive method. 1514 */ 1515 int 1516 userauth_kbdint(Authctxt *authctxt) 1517 { 1518 static int attempt = 0; 1519 1520 if (attempt++ >= options.number_of_password_prompts) 1521 return 0; 1522 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1523 if (attempt > 1 && !authctxt->info_req_seen) { 1524 debug3("userauth_kbdint: disable: no info_req_seen"); 1525 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1526 return 0; 1527 } 1528 1529 debug2("userauth_kbdint"); 1530 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1531 packet_put_cstring(authctxt->server_user); 1532 packet_put_cstring(authctxt->service); 1533 packet_put_cstring(authctxt->method->name); 1534 packet_put_cstring(""); /* lang */ 1535 packet_put_cstring(options.kbd_interactive_devices ? 1536 options.kbd_interactive_devices : ""); 1537 packet_send(); 1538 1539 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1540 return 1; 1541 } 1542 1543 /* 1544 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1545 */ 1546 void 1547 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1548 { 1549 Authctxt *authctxt = ctxt; 1550 char *name, *inst, *lang, *prompt, *response; 1551 u_int num_prompts, i; 1552 int echo = 0; 1553 1554 debug2("input_userauth_info_req"); 1555 1556 if (authctxt == NULL) 1557 fatal("input_userauth_info_req: no authentication context"); 1558 1559 authctxt->info_req_seen = 1; 1560 1561 name = packet_get_string(NULL); 1562 inst = packet_get_string(NULL); 1563 lang = packet_get_string(NULL); 1564 if (strlen(name) > 0) 1565 logit("%s", name); 1566 if (strlen(inst) > 0) 1567 logit("%s", inst); 1568 xfree(name); 1569 xfree(inst); 1570 xfree(lang); 1571 1572 num_prompts = packet_get_int(); 1573 /* 1574 * Begin to build info response packet based on prompts requested. 1575 * We commit to providing the correct number of responses, so if 1576 * further on we run into a problem that prevents this, we have to 1577 * be sure and clean this up and send a correct error response. 1578 */ 1579 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1580 packet_put_int(num_prompts); 1581 1582 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1583 for (i = 0; i < num_prompts; i++) { 1584 prompt = packet_get_string(NULL); 1585 echo = packet_get_char(); 1586 1587 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1588 1589 packet_put_cstring(response); 1590 memset(response, 0, strlen(response)); 1591 xfree(response); 1592 xfree(prompt); 1593 } 1594 packet_check_eom(); /* done with parsing incoming message. */ 1595 1596 packet_add_padding(64); 1597 packet_send(); 1598 } 1599 1600 static int 1601 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1602 u_char *data, u_int datalen) 1603 { 1604 Buffer b; 1605 struct stat st; 1606 pid_t pid; 1607 int to[2], from[2], status, version = 2; 1608 1609 debug2("ssh_keysign called"); 1610 1611 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1612 error("ssh_keysign: not installed: %s", strerror(errno)); 1613 return -1; 1614 } 1615 if (fflush(stdout) != 0) 1616 error("ssh_keysign: fflush: %s", strerror(errno)); 1617 if (pipe(to) < 0) { 1618 error("ssh_keysign: pipe: %s", strerror(errno)); 1619 return -1; 1620 } 1621 if (pipe(from) < 0) { 1622 error("ssh_keysign: pipe: %s", strerror(errno)); 1623 return -1; 1624 } 1625 if ((pid = fork()) < 0) { 1626 error("ssh_keysign: fork: %s", strerror(errno)); 1627 return -1; 1628 } 1629 if (pid == 0) { 1630 /* keep the socket on exec */ 1631 fcntl(packet_get_connection_in(), F_SETFD, 0); 1632 permanently_drop_suid(getuid()); 1633 close(from[0]); 1634 if (dup2(from[1], STDOUT_FILENO) < 0) 1635 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1636 close(to[1]); 1637 if (dup2(to[0], STDIN_FILENO) < 0) 1638 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1639 close(from[1]); 1640 close(to[0]); 1641 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1642 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1643 strerror(errno)); 1644 } 1645 close(from[1]); 1646 close(to[0]); 1647 1648 buffer_init(&b); 1649 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1650 buffer_put_string(&b, data, datalen); 1651 if (ssh_msg_send(to[1], version, &b) == -1) 1652 fatal("ssh_keysign: couldn't send request"); 1653 1654 if (ssh_msg_recv(from[0], &b) < 0) { 1655 error("ssh_keysign: no reply"); 1656 buffer_free(&b); 1657 return -1; 1658 } 1659 close(from[0]); 1660 close(to[1]); 1661 1662 while (waitpid(pid, &status, 0) < 0) 1663 if (errno != EINTR) 1664 break; 1665 1666 if (buffer_get_char(&b) != version) { 1667 error("ssh_keysign: bad version"); 1668 buffer_free(&b); 1669 return -1; 1670 } 1671 *sigp = buffer_get_string(&b, lenp); 1672 buffer_free(&b); 1673 1674 return 0; 1675 } 1676 1677 int 1678 userauth_hostbased(Authctxt *authctxt) 1679 { 1680 Key *private = NULL; 1681 Sensitive *sensitive = authctxt->sensitive; 1682 Buffer b; 1683 u_char *signature, *blob; 1684 char *chost, *pkalg, *p; 1685 const char *service; 1686 u_int blen, slen; 1687 int ok, i, found = 0; 1688 1689 /* check for a useful key */ 1690 for (i = 0; i < sensitive->nkeys; i++) { 1691 private = sensitive->keys[i]; 1692 if (private && private->type != KEY_RSA1) { 1693 found = 1; 1694 /* we take and free the key */ 1695 sensitive->keys[i] = NULL; 1696 break; 1697 } 1698 } 1699 if (!found) { 1700 debug("No more client hostkeys for hostbased authentication."); 1701 return 0; 1702 } 1703 if (key_to_blob(private, &blob, &blen) == 0) { 1704 key_free(private); 1705 return 0; 1706 } 1707 /* figure out a name for the client host */ 1708 p = get_local_name(packet_get_connection_in()); 1709 if (p == NULL) { 1710 error("userauth_hostbased: cannot get local ipaddr/name"); 1711 key_free(private); 1712 xfree(blob); 1713 return 0; 1714 } 1715 xasprintf(&chost, "%s.", p); 1716 debug2("userauth_hostbased: chost %s", chost); 1717 xfree(p); 1718 1719 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1720 authctxt->service; 1721 pkalg = xstrdup(key_ssh_name(private)); 1722 buffer_init(&b); 1723 /* construct data */ 1724 buffer_put_string(&b, session_id2, session_id2_len); 1725 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1726 buffer_put_cstring(&b, authctxt->server_user); 1727 buffer_put_cstring(&b, service); 1728 buffer_put_cstring(&b, authctxt->method->name); 1729 buffer_put_cstring(&b, pkalg); 1730 buffer_put_string(&b, blob, blen); 1731 buffer_put_cstring(&b, chost); 1732 buffer_put_cstring(&b, authctxt->local_user); 1733 #ifdef DEBUG_PK 1734 buffer_dump(&b); 1735 #endif 1736 if (sensitive->external_keysign) 1737 ok = ssh_keysign(private, &signature, &slen, 1738 buffer_ptr(&b), buffer_len(&b)); 1739 else 1740 ok = key_sign(private, &signature, &slen, 1741 buffer_ptr(&b), buffer_len(&b)); 1742 key_free(private); 1743 buffer_free(&b); 1744 if (ok != 0) { 1745 error("key_sign failed"); 1746 xfree(chost); 1747 xfree(pkalg); 1748 xfree(blob); 1749 return 0; 1750 } 1751 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1752 packet_put_cstring(authctxt->server_user); 1753 packet_put_cstring(authctxt->service); 1754 packet_put_cstring(authctxt->method->name); 1755 packet_put_cstring(pkalg); 1756 packet_put_string(blob, blen); 1757 packet_put_cstring(chost); 1758 packet_put_cstring(authctxt->local_user); 1759 packet_put_string(signature, slen); 1760 memset(signature, 's', slen); 1761 xfree(signature); 1762 xfree(chost); 1763 xfree(pkalg); 1764 xfree(blob); 1765 1766 packet_send(); 1767 return 1; 1768 } 1769 1770 #ifdef JPAKE 1771 int 1772 userauth_jpake(Authctxt *authctxt) 1773 { 1774 struct jpake_ctx *pctx; 1775 u_char *x1_proof, *x2_proof; 1776 u_int x1_proof_len, x2_proof_len; 1777 static int attempt = 0; /* XXX share with userauth_password's? */ 1778 1779 if (attempt++ >= options.number_of_password_prompts) 1780 return 0; 1781 if (attempt != 1) 1782 error("Permission denied, please try again."); 1783 1784 if (authctxt->methoddata != NULL) 1785 fatal("%s: authctxt->methoddata already set (%p)", 1786 __func__, authctxt->methoddata); 1787 1788 authctxt->methoddata = pctx = jpake_new(); 1789 1790 /* 1791 * Send request immediately, to get the protocol going while 1792 * we do the initial computations. 1793 */ 1794 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1795 packet_put_cstring(authctxt->server_user); 1796 packet_put_cstring(authctxt->service); 1797 packet_put_cstring(authctxt->method->name); 1798 packet_send(); 1799 packet_write_wait(); 1800 1801 jpake_step1(pctx->grp, 1802 &pctx->client_id, &pctx->client_id_len, 1803 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1804 &x1_proof, &x1_proof_len, 1805 &x2_proof, &x2_proof_len); 1806 1807 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1808 1809 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1810 packet_put_string(pctx->client_id, pctx->client_id_len); 1811 packet_put_bignum2(pctx->g_x1); 1812 packet_put_bignum2(pctx->g_x2); 1813 packet_put_string(x1_proof, x1_proof_len); 1814 packet_put_string(x2_proof, x2_proof_len); 1815 packet_send(); 1816 1817 bzero(x1_proof, x1_proof_len); 1818 bzero(x2_proof, x2_proof_len); 1819 xfree(x1_proof); 1820 xfree(x2_proof); 1821 1822 /* Expect step 1 packet from peer */ 1823 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1824 input_userauth_jpake_server_step1); 1825 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1826 &input_userauth_success_unexpected); 1827 1828 return 1; 1829 } 1830 1831 void 1832 userauth_jpake_cleanup(Authctxt *authctxt) 1833 { 1834 debug3("%s: clean up", __func__); 1835 if (authctxt->methoddata != NULL) { 1836 jpake_free(authctxt->methoddata); 1837 authctxt->methoddata = NULL; 1838 } 1839 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1840 } 1841 #endif /* JPAKE */ 1842 1843 /* find auth method */ 1844 1845 /* 1846 * given auth method name, if configurable options permit this method fill 1847 * in auth_ident field and return true, otherwise return false. 1848 */ 1849 static int 1850 authmethod_is_enabled(Authmethod *method) 1851 { 1852 if (method == NULL) 1853 return 0; 1854 /* return false if options indicate this method is disabled */ 1855 if (method->enabled == NULL || *method->enabled == 0) 1856 return 0; 1857 /* return false if batch mode is enabled but method needs interactive mode */ 1858 if (method->batch_flag != NULL && *method->batch_flag != 0) 1859 return 0; 1860 return 1; 1861 } 1862 1863 static Authmethod * 1864 authmethod_lookup(const char *name) 1865 { 1866 Authmethod *method = NULL; 1867 if (name != NULL) 1868 for (method = authmethods; method->name != NULL; method++) 1869 if (strcmp(name, method->name) == 0) 1870 return method; 1871 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1872 return NULL; 1873 } 1874 1875 /* XXX internal state */ 1876 static Authmethod *current = NULL; 1877 static char *supported = NULL; 1878 static char *preferred = NULL; 1879 1880 /* 1881 * Given the authentication method list sent by the server, return the 1882 * next method we should try. If the server initially sends a nil list, 1883 * use a built-in default list. 1884 */ 1885 static Authmethod * 1886 authmethod_get(char *authlist) 1887 { 1888 char *name = NULL; 1889 u_int next; 1890 1891 /* Use a suitable default if we're passed a nil list. */ 1892 if (authlist == NULL || strlen(authlist) == 0) 1893 authlist = options.preferred_authentications; 1894 1895 if (supported == NULL || strcmp(authlist, supported) != 0) { 1896 debug3("start over, passed a different list %s", authlist); 1897 if (supported != NULL) 1898 xfree(supported); 1899 supported = xstrdup(authlist); 1900 preferred = options.preferred_authentications; 1901 debug3("preferred %s", preferred); 1902 current = NULL; 1903 } else if (current != NULL && authmethod_is_enabled(current)) 1904 return current; 1905 1906 for (;;) { 1907 if ((name = match_list(preferred, supported, &next)) == NULL) { 1908 debug("No more authentication methods to try."); 1909 current = NULL; 1910 return NULL; 1911 } 1912 preferred += next; 1913 debug3("authmethod_lookup %s", name); 1914 debug3("remaining preferred: %s", preferred); 1915 if ((current = authmethod_lookup(name)) != NULL && 1916 authmethod_is_enabled(current)) { 1917 debug3("authmethod_is_enabled %s", name); 1918 debug("Next authentication method: %s", name); 1919 return current; 1920 } 1921 } 1922 } 1923 1924 static char * 1925 authmethods_get(void) 1926 { 1927 Authmethod *method = NULL; 1928 Buffer b; 1929 char *list; 1930 1931 buffer_init(&b); 1932 for (method = authmethods; method->name != NULL; method++) { 1933 if (authmethod_is_enabled(method)) { 1934 if (buffer_len(&b) > 0) 1935 buffer_append(&b, ",", 1); 1936 buffer_append(&b, method->name, strlen(method->name)); 1937 } 1938 } 1939 buffer_append(&b, "\0", 1); 1940 list = xstrdup(buffer_ptr(&b)); 1941 buffer_free(&b); 1942 return list; 1943 } 1944 1945