1 /* $OpenBSD: sshconnect2.c,v 1.188 2011/05/24 07:15:47 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 85 /* 86 * SSH2 key exchange 87 */ 88 89 u_char *session_id2 = NULL; 90 u_int session_id2_len = 0; 91 92 char *xxx_host; 93 struct sockaddr *xxx_hostaddr; 94 95 Kex *xxx_kex = NULL; 96 97 static int 98 verify_host_key_callback(Key *hostkey) 99 { 100 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 101 fatal("Host key verification failed."); 102 return 0; 103 } 104 105 static char * 106 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 107 { 108 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 109 size_t maxlen; 110 struct hostkeys *hostkeys; 111 int ktype; 112 u_int i; 113 114 /* Find all hostkeys for this hostname */ 115 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 116 hostkeys = init_hostkeys(); 117 for (i = 0; i < options.num_user_hostfiles; i++) 118 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 119 for (i = 0; i < options.num_system_hostfiles; i++) 120 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 121 122 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 123 maxlen = strlen(avail) + 1; 124 first = xmalloc(maxlen); 125 last = xmalloc(maxlen); 126 *first = *last = '\0'; 127 128 #define ALG_APPEND(to, from) \ 129 do { \ 130 if (*to != '\0') \ 131 strlcat(to, ",", maxlen); \ 132 strlcat(to, from, maxlen); \ 133 } while (0) 134 135 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 136 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 137 fatal("%s: unknown alg %s", __func__, alg); 138 if (lookup_key_in_hostkeys_by_type(hostkeys, 139 key_type_plain(ktype), NULL)) 140 ALG_APPEND(first, alg); 141 else 142 ALG_APPEND(last, alg); 143 } 144 #undef ALG_APPEND 145 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 146 if (*first != '\0') 147 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 148 149 xfree(first); 150 xfree(last); 151 xfree(hostname); 152 xfree(oavail); 153 free_hostkeys(hostkeys); 154 155 return ret; 156 } 157 158 void 159 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 160 { 161 Kex *kex; 162 163 xxx_host = host; 164 xxx_hostaddr = hostaddr; 165 166 if (options.ciphers == (char *)-1) { 167 logit("No valid ciphers for protocol version 2 given, using defaults."); 168 options.ciphers = NULL; 169 } 170 if (options.ciphers != NULL) { 171 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 172 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 173 } 174 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 175 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 176 myproposal[PROPOSAL_ENC_ALGS_STOC] = 177 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 178 if (options.compression) { 179 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 180 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib (at) openssh.com,zlib,none"; 181 } else { 182 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 183 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib (at) openssh.com,zlib"; 184 } 185 if (options.macs != NULL) { 186 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 187 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 188 } 189 if (options.hostkeyalgorithms != NULL) 190 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 191 options.hostkeyalgorithms; 192 else { 193 /* Prefer algorithms that we already have keys for */ 194 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 195 order_hostkeyalgs(host, hostaddr, port); 196 } 197 if (options.kex_algorithms != NULL) 198 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 199 200 if (options.rekey_limit) 201 packet_set_rekey_limit((u_int32_t)options.rekey_limit); 202 203 /* start key exchange */ 204 kex = kex_setup(myproposal); 205 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 206 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 207 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 208 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 209 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 210 kex->client_version_string=client_version_string; 211 kex->server_version_string=server_version_string; 212 kex->verify_host_key=&verify_host_key_callback; 213 214 xxx_kex = kex; 215 216 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 217 218 if (options.use_roaming && !kex->roaming) { 219 debug("Roaming not allowed by server"); 220 options.use_roaming = 0; 221 } 222 223 session_id2 = kex->session_id; 224 session_id2_len = kex->session_id_len; 225 226 #ifdef DEBUG_KEXDH 227 /* send 1st encrypted/maced/compressed message */ 228 packet_start(SSH2_MSG_IGNORE); 229 packet_put_cstring("markus"); 230 packet_send(); 231 packet_write_wait(); 232 #endif 233 } 234 235 /* 236 * Authenticate user 237 */ 238 239 typedef struct Authctxt Authctxt; 240 typedef struct Authmethod Authmethod; 241 typedef struct identity Identity; 242 typedef struct idlist Idlist; 243 244 struct identity { 245 TAILQ_ENTRY(identity) next; 246 AuthenticationConnection *ac; /* set if agent supports key */ 247 Key *key; /* public/private key */ 248 char *filename; /* comment for agent-only keys */ 249 int tried; 250 int isprivate; /* key points to the private key */ 251 }; 252 TAILQ_HEAD(idlist, identity); 253 254 struct Authctxt { 255 const char *server_user; 256 const char *local_user; 257 const char *host; 258 const char *service; 259 Authmethod *method; 260 sig_atomic_t success; 261 char *authlist; 262 /* pubkey */ 263 Idlist keys; 264 AuthenticationConnection *agent; 265 /* hostbased */ 266 Sensitive *sensitive; 267 /* kbd-interactive */ 268 int info_req_seen; 269 /* generic */ 270 void *methoddata; 271 }; 272 struct Authmethod { 273 char *name; /* string to compare against server's list */ 274 int (*userauth)(Authctxt *authctxt); 275 void (*cleanup)(Authctxt *authctxt); 276 int *enabled; /* flag in option struct that enables method */ 277 int *batch_flag; /* flag in option struct that disables method */ 278 }; 279 280 void input_userauth_success(int, u_int32_t, void *); 281 void input_userauth_success_unexpected(int, u_int32_t, void *); 282 void input_userauth_failure(int, u_int32_t, void *); 283 void input_userauth_banner(int, u_int32_t, void *); 284 void input_userauth_error(int, u_int32_t, void *); 285 void input_userauth_info_req(int, u_int32_t, void *); 286 void input_userauth_pk_ok(int, u_int32_t, void *); 287 void input_userauth_passwd_changereq(int, u_int32_t, void *); 288 void input_userauth_jpake_server_step1(int, u_int32_t, void *); 289 void input_userauth_jpake_server_step2(int, u_int32_t, void *); 290 void input_userauth_jpake_server_confirm(int, u_int32_t, void *); 291 292 int userauth_none(Authctxt *); 293 int userauth_pubkey(Authctxt *); 294 int userauth_passwd(Authctxt *); 295 int userauth_kbdint(Authctxt *); 296 int userauth_hostbased(Authctxt *); 297 int userauth_jpake(Authctxt *); 298 299 void userauth_jpake_cleanup(Authctxt *); 300 301 #ifdef GSSAPI 302 int userauth_gssapi(Authctxt *authctxt); 303 void input_gssapi_response(int type, u_int32_t, void *); 304 void input_gssapi_token(int type, u_int32_t, void *); 305 void input_gssapi_hash(int type, u_int32_t, void *); 306 void input_gssapi_error(int, u_int32_t, void *); 307 void input_gssapi_errtok(int, u_int32_t, void *); 308 #endif 309 310 void userauth(Authctxt *, char *); 311 312 static int sign_and_send_pubkey(Authctxt *, Identity *); 313 static void pubkey_prepare(Authctxt *); 314 static void pubkey_cleanup(Authctxt *); 315 static Key *load_identity_file(char *); 316 317 static Authmethod *authmethod_get(char *authlist); 318 static Authmethod *authmethod_lookup(const char *name); 319 static char *authmethods_get(void); 320 321 Authmethod authmethods[] = { 322 #ifdef GSSAPI 323 {"gssapi-with-mic", 324 userauth_gssapi, 325 NULL, 326 &options.gss_authentication, 327 NULL}, 328 #endif 329 {"hostbased", 330 userauth_hostbased, 331 NULL, 332 &options.hostbased_authentication, 333 NULL}, 334 {"publickey", 335 userauth_pubkey, 336 NULL, 337 &options.pubkey_authentication, 338 NULL}, 339 #ifdef JPAKE 340 {"jpake-01 (at) openssh.com", 341 userauth_jpake, 342 userauth_jpake_cleanup, 343 &options.zero_knowledge_password_authentication, 344 &options.batch_mode}, 345 #endif 346 {"keyboard-interactive", 347 userauth_kbdint, 348 NULL, 349 &options.kbd_interactive_authentication, 350 &options.batch_mode}, 351 {"password", 352 userauth_passwd, 353 NULL, 354 &options.password_authentication, 355 &options.batch_mode}, 356 {"none", 357 userauth_none, 358 NULL, 359 NULL, 360 NULL}, 361 {NULL, NULL, NULL, NULL, NULL} 362 }; 363 364 void 365 ssh_userauth2(const char *local_user, const char *server_user, char *host, 366 Sensitive *sensitive) 367 { 368 Authctxt authctxt; 369 int type; 370 371 if (options.challenge_response_authentication) 372 options.kbd_interactive_authentication = 1; 373 374 packet_start(SSH2_MSG_SERVICE_REQUEST); 375 packet_put_cstring("ssh-userauth"); 376 packet_send(); 377 debug("SSH2_MSG_SERVICE_REQUEST sent"); 378 packet_write_wait(); 379 type = packet_read(); 380 if (type != SSH2_MSG_SERVICE_ACCEPT) 381 fatal("Server denied authentication request: %d", type); 382 if (packet_remaining() > 0) { 383 char *reply = packet_get_string(NULL); 384 debug2("service_accept: %s", reply); 385 xfree(reply); 386 } else { 387 debug2("buggy server: service_accept w/o service"); 388 } 389 packet_check_eom(); 390 debug("SSH2_MSG_SERVICE_ACCEPT received"); 391 392 if (options.preferred_authentications == NULL) 393 options.preferred_authentications = authmethods_get(); 394 395 /* setup authentication context */ 396 memset(&authctxt, 0, sizeof(authctxt)); 397 pubkey_prepare(&authctxt); 398 authctxt.server_user = server_user; 399 authctxt.local_user = local_user; 400 authctxt.host = host; 401 authctxt.service = "ssh-connection"; /* service name */ 402 authctxt.success = 0; 403 authctxt.method = authmethod_lookup("none"); 404 authctxt.authlist = NULL; 405 authctxt.methoddata = NULL; 406 authctxt.sensitive = sensitive; 407 authctxt.info_req_seen = 0; 408 if (authctxt.method == NULL) 409 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 410 411 /* initial userauth request */ 412 userauth_none(&authctxt); 413 414 dispatch_init(&input_userauth_error); 415 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 416 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 417 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 418 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 419 420 pubkey_cleanup(&authctxt); 421 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 422 423 debug("Authentication succeeded (%s).", authctxt.method->name); 424 } 425 426 void 427 userauth(Authctxt *authctxt, char *authlist) 428 { 429 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 430 authctxt->method->cleanup(authctxt); 431 432 if (authctxt->methoddata) { 433 xfree(authctxt->methoddata); 434 authctxt->methoddata = NULL; 435 } 436 if (authlist == NULL) { 437 authlist = authctxt->authlist; 438 } else { 439 if (authctxt->authlist) 440 xfree(authctxt->authlist); 441 authctxt->authlist = authlist; 442 } 443 for (;;) { 444 Authmethod *method = authmethod_get(authlist); 445 if (method == NULL) 446 fatal("Permission denied (%s).", authlist); 447 authctxt->method = method; 448 449 /* reset the per method handler */ 450 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 451 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 452 453 /* and try new method */ 454 if (method->userauth(authctxt) != 0) { 455 debug2("we sent a %s packet, wait for reply", method->name); 456 break; 457 } else { 458 debug2("we did not send a packet, disable method"); 459 method->enabled = NULL; 460 } 461 } 462 } 463 464 /* ARGSUSED */ 465 void 466 input_userauth_error(int type, u_int32_t seq, void *ctxt) 467 { 468 fatal("input_userauth_error: bad message during authentication: " 469 "type %d", type); 470 } 471 472 /* ARGSUSED */ 473 void 474 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 475 { 476 char *msg, *raw, *lang; 477 u_int len; 478 479 debug3("input_userauth_banner"); 480 raw = packet_get_string(&len); 481 lang = packet_get_string(NULL); 482 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 483 if (len > 65536) 484 len = 65536; 485 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 486 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 487 fprintf(stderr, "%s", msg); 488 xfree(msg); 489 } 490 xfree(raw); 491 xfree(lang); 492 } 493 494 /* ARGSUSED */ 495 void 496 input_userauth_success(int type, u_int32_t seq, void *ctxt) 497 { 498 Authctxt *authctxt = ctxt; 499 500 if (authctxt == NULL) 501 fatal("input_userauth_success: no authentication context"); 502 if (authctxt->authlist) { 503 xfree(authctxt->authlist); 504 authctxt->authlist = NULL; 505 } 506 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 507 authctxt->method->cleanup(authctxt); 508 if (authctxt->methoddata) { 509 xfree(authctxt->methoddata); 510 authctxt->methoddata = NULL; 511 } 512 authctxt->success = 1; /* break out */ 513 } 514 515 void 516 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 517 { 518 Authctxt *authctxt = ctxt; 519 520 if (authctxt == NULL) 521 fatal("%s: no authentication context", __func__); 522 523 fatal("Unexpected authentication success during %s.", 524 authctxt->method->name); 525 } 526 527 /* ARGSUSED */ 528 void 529 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 530 { 531 Authctxt *authctxt = ctxt; 532 char *authlist = NULL; 533 int partial; 534 535 if (authctxt == NULL) 536 fatal("input_userauth_failure: no authentication context"); 537 538 authlist = packet_get_string(NULL); 539 partial = packet_get_char(); 540 packet_check_eom(); 541 542 if (partial != 0) 543 logit("Authenticated with partial success."); 544 debug("Authentications that can continue: %s", authlist); 545 546 userauth(authctxt, authlist); 547 } 548 549 /* ARGSUSED */ 550 void 551 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 552 { 553 Authctxt *authctxt = ctxt; 554 Key *key = NULL; 555 Identity *id = NULL; 556 Buffer b; 557 int pktype, sent = 0; 558 u_int alen, blen; 559 char *pkalg, *fp; 560 u_char *pkblob; 561 562 if (authctxt == NULL) 563 fatal("input_userauth_pk_ok: no authentication context"); 564 if (datafellows & SSH_BUG_PKOK) { 565 /* this is similar to SSH_BUG_PKAUTH */ 566 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 567 pkblob = packet_get_string(&blen); 568 buffer_init(&b); 569 buffer_append(&b, pkblob, blen); 570 pkalg = buffer_get_string(&b, &alen); 571 buffer_free(&b); 572 } else { 573 pkalg = packet_get_string(&alen); 574 pkblob = packet_get_string(&blen); 575 } 576 packet_check_eom(); 577 578 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 579 580 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 581 debug("unknown pkalg %s", pkalg); 582 goto done; 583 } 584 if ((key = key_from_blob(pkblob, blen)) == NULL) { 585 debug("no key from blob. pkalg %s", pkalg); 586 goto done; 587 } 588 if (key->type != pktype) { 589 error("input_userauth_pk_ok: type mismatch " 590 "for decoded key (received %d, expected %d)", 591 key->type, pktype); 592 goto done; 593 } 594 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 595 debug2("input_userauth_pk_ok: fp %s", fp); 596 xfree(fp); 597 598 /* 599 * search keys in the reverse order, because last candidate has been 600 * moved to the end of the queue. this also avoids confusion by 601 * duplicate keys 602 */ 603 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 604 if (key_equal(key, id->key)) { 605 sent = sign_and_send_pubkey(authctxt, id); 606 break; 607 } 608 } 609 done: 610 if (key != NULL) 611 key_free(key); 612 xfree(pkalg); 613 xfree(pkblob); 614 615 /* try another method if we did not send a packet */ 616 if (sent == 0) 617 userauth(authctxt, NULL); 618 } 619 620 #ifdef GSSAPI 621 int 622 userauth_gssapi(Authctxt *authctxt) 623 { 624 Gssctxt *gssctxt = NULL; 625 static gss_OID_set gss_supported = NULL; 626 static u_int mech = 0; 627 OM_uint32 min; 628 int ok = 0; 629 630 /* Try one GSSAPI method at a time, rather than sending them all at 631 * once. */ 632 633 if (gss_supported == NULL) 634 gss_indicate_mechs(&min, &gss_supported); 635 636 /* Check to see if the mechanism is usable before we offer it */ 637 while (mech < gss_supported->count && !ok) { 638 /* My DER encoding requires length<128 */ 639 if (gss_supported->elements[mech].length < 128 && 640 ssh_gssapi_check_mechanism(&gssctxt, 641 &gss_supported->elements[mech], authctxt->host)) { 642 ok = 1; /* Mechanism works */ 643 } else { 644 mech++; 645 } 646 } 647 648 if (!ok) 649 return 0; 650 651 authctxt->methoddata=(void *)gssctxt; 652 653 packet_start(SSH2_MSG_USERAUTH_REQUEST); 654 packet_put_cstring(authctxt->server_user); 655 packet_put_cstring(authctxt->service); 656 packet_put_cstring(authctxt->method->name); 657 658 packet_put_int(1); 659 660 packet_put_int((gss_supported->elements[mech].length) + 2); 661 packet_put_char(SSH_GSS_OIDTYPE); 662 packet_put_char(gss_supported->elements[mech].length); 663 packet_put_raw(gss_supported->elements[mech].elements, 664 gss_supported->elements[mech].length); 665 666 packet_send(); 667 668 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 669 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 670 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 671 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 672 673 mech++; /* Move along to next candidate */ 674 675 return 1; 676 } 677 678 static OM_uint32 679 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 680 { 681 Authctxt *authctxt = ctxt; 682 Gssctxt *gssctxt = authctxt->methoddata; 683 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 684 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 685 gss_buffer_desc gssbuf; 686 OM_uint32 status, ms, flags; 687 Buffer b; 688 689 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 690 recv_tok, &send_tok, &flags); 691 692 if (send_tok.length > 0) { 693 if (GSS_ERROR(status)) 694 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 695 else 696 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 697 698 packet_put_string(send_tok.value, send_tok.length); 699 packet_send(); 700 gss_release_buffer(&ms, &send_tok); 701 } 702 703 if (status == GSS_S_COMPLETE) { 704 /* send either complete or MIC, depending on mechanism */ 705 if (!(flags & GSS_C_INTEG_FLAG)) { 706 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 707 packet_send(); 708 } else { 709 ssh_gssapi_buildmic(&b, authctxt->server_user, 710 authctxt->service, "gssapi-with-mic"); 711 712 gssbuf.value = buffer_ptr(&b); 713 gssbuf.length = buffer_len(&b); 714 715 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 716 717 if (!GSS_ERROR(status)) { 718 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 719 packet_put_string(mic.value, mic.length); 720 721 packet_send(); 722 } 723 724 buffer_free(&b); 725 gss_release_buffer(&ms, &mic); 726 } 727 } 728 729 return status; 730 } 731 732 /* ARGSUSED */ 733 void 734 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 735 { 736 Authctxt *authctxt = ctxt; 737 Gssctxt *gssctxt; 738 int oidlen; 739 char *oidv; 740 741 if (authctxt == NULL) 742 fatal("input_gssapi_response: no authentication context"); 743 gssctxt = authctxt->methoddata; 744 745 /* Setup our OID */ 746 oidv = packet_get_string(&oidlen); 747 748 if (oidlen <= 2 || 749 oidv[0] != SSH_GSS_OIDTYPE || 750 oidv[1] != oidlen - 2) { 751 xfree(oidv); 752 debug("Badly encoded mechanism OID received"); 753 userauth(authctxt, NULL); 754 return; 755 } 756 757 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 758 fatal("Server returned different OID than expected"); 759 760 packet_check_eom(); 761 762 xfree(oidv); 763 764 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 765 /* Start again with next method on list */ 766 debug("Trying to start again"); 767 userauth(authctxt, NULL); 768 return; 769 } 770 } 771 772 /* ARGSUSED */ 773 void 774 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 775 { 776 Authctxt *authctxt = ctxt; 777 gss_buffer_desc recv_tok; 778 OM_uint32 status; 779 u_int slen; 780 781 if (authctxt == NULL) 782 fatal("input_gssapi_response: no authentication context"); 783 784 recv_tok.value = packet_get_string(&slen); 785 recv_tok.length = slen; /* safe typecast */ 786 787 packet_check_eom(); 788 789 status = process_gssapi_token(ctxt, &recv_tok); 790 791 xfree(recv_tok.value); 792 793 if (GSS_ERROR(status)) { 794 /* Start again with the next method in the list */ 795 userauth(authctxt, NULL); 796 return; 797 } 798 } 799 800 /* ARGSUSED */ 801 void 802 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 803 { 804 Authctxt *authctxt = ctxt; 805 Gssctxt *gssctxt; 806 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 807 gss_buffer_desc recv_tok; 808 OM_uint32 status, ms; 809 u_int len; 810 811 if (authctxt == NULL) 812 fatal("input_gssapi_response: no authentication context"); 813 gssctxt = authctxt->methoddata; 814 815 recv_tok.value = packet_get_string(&len); 816 recv_tok.length = len; 817 818 packet_check_eom(); 819 820 /* Stick it into GSSAPI and see what it says */ 821 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 822 &recv_tok, &send_tok, NULL); 823 824 xfree(recv_tok.value); 825 gss_release_buffer(&ms, &send_tok); 826 827 /* Server will be returning a failed packet after this one */ 828 } 829 830 /* ARGSUSED */ 831 void 832 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 833 { 834 OM_uint32 maj, min; 835 char *msg; 836 char *lang; 837 838 maj=packet_get_int(); 839 min=packet_get_int(); 840 msg=packet_get_string(NULL); 841 lang=packet_get_string(NULL); 842 843 packet_check_eom(); 844 845 debug("Server GSSAPI Error:\n%s", msg); 846 xfree(msg); 847 xfree(lang); 848 } 849 #endif /* GSSAPI */ 850 851 int 852 userauth_none(Authctxt *authctxt) 853 { 854 /* initial userauth request */ 855 packet_start(SSH2_MSG_USERAUTH_REQUEST); 856 packet_put_cstring(authctxt->server_user); 857 packet_put_cstring(authctxt->service); 858 packet_put_cstring(authctxt->method->name); 859 packet_send(); 860 return 1; 861 } 862 863 int 864 userauth_passwd(Authctxt *authctxt) 865 { 866 static int attempt = 0; 867 char prompt[150]; 868 char *password; 869 const char *host = options.host_key_alias ? options.host_key_alias : 870 authctxt->host; 871 872 if (attempt++ >= options.number_of_password_prompts) 873 return 0; 874 875 if (attempt != 1) 876 error("Permission denied, please try again."); 877 878 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 879 authctxt->server_user, host); 880 password = read_passphrase(prompt, 0); 881 packet_start(SSH2_MSG_USERAUTH_REQUEST); 882 packet_put_cstring(authctxt->server_user); 883 packet_put_cstring(authctxt->service); 884 packet_put_cstring(authctxt->method->name); 885 packet_put_char(0); 886 packet_put_cstring(password); 887 memset(password, 0, strlen(password)); 888 xfree(password); 889 packet_add_padding(64); 890 packet_send(); 891 892 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 893 &input_userauth_passwd_changereq); 894 895 return 1; 896 } 897 898 /* 899 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 900 */ 901 /* ARGSUSED */ 902 void 903 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 904 { 905 Authctxt *authctxt = ctxt; 906 char *info, *lang, *password = NULL, *retype = NULL; 907 char prompt[150]; 908 const char *host = options.host_key_alias ? options.host_key_alias : 909 authctxt->host; 910 911 debug2("input_userauth_passwd_changereq"); 912 913 if (authctxt == NULL) 914 fatal("input_userauth_passwd_changereq: " 915 "no authentication context"); 916 917 info = packet_get_string(NULL); 918 lang = packet_get_string(NULL); 919 if (strlen(info) > 0) 920 logit("%s", info); 921 xfree(info); 922 xfree(lang); 923 packet_start(SSH2_MSG_USERAUTH_REQUEST); 924 packet_put_cstring(authctxt->server_user); 925 packet_put_cstring(authctxt->service); 926 packet_put_cstring(authctxt->method->name); 927 packet_put_char(1); /* additional info */ 928 snprintf(prompt, sizeof(prompt), 929 "Enter %.30s@%.128s's old password: ", 930 authctxt->server_user, host); 931 password = read_passphrase(prompt, 0); 932 packet_put_cstring(password); 933 memset(password, 0, strlen(password)); 934 xfree(password); 935 password = NULL; 936 while (password == NULL) { 937 snprintf(prompt, sizeof(prompt), 938 "Enter %.30s@%.128s's new password: ", 939 authctxt->server_user, host); 940 password = read_passphrase(prompt, RP_ALLOW_EOF); 941 if (password == NULL) { 942 /* bail out */ 943 return; 944 } 945 snprintf(prompt, sizeof(prompt), 946 "Retype %.30s@%.128s's new password: ", 947 authctxt->server_user, host); 948 retype = read_passphrase(prompt, 0); 949 if (strcmp(password, retype) != 0) { 950 memset(password, 0, strlen(password)); 951 xfree(password); 952 logit("Mismatch; try again, EOF to quit."); 953 password = NULL; 954 } 955 memset(retype, 0, strlen(retype)); 956 xfree(retype); 957 } 958 packet_put_cstring(password); 959 memset(password, 0, strlen(password)); 960 xfree(password); 961 packet_add_padding(64); 962 packet_send(); 963 964 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 965 &input_userauth_passwd_changereq); 966 } 967 968 #ifdef JPAKE 969 static char * 970 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) 971 { 972 /* OpenBSD crypt(3) handles all of these */ 973 if (strcmp(crypt_scheme, "crypt") == 0 || 974 strcmp(crypt_scheme, "bcrypt") == 0 || 975 strcmp(crypt_scheme, "md5crypt") == 0 || 976 strcmp(crypt_scheme, "crypt-extended") == 0) 977 return xstrdup(crypt(password, salt)); 978 error("%s: unsupported password encryption scheme \"%.100s\"", 979 __func__, crypt_scheme); 980 return NULL; 981 } 982 983 static BIGNUM * 984 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, 985 const char *salt) 986 { 987 char prompt[256], *password, *crypted; 988 u_char *secret; 989 u_int secret_len; 990 BIGNUM *ret; 991 992 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", 993 authctxt->server_user, authctxt->host); 994 password = read_passphrase(prompt, 0); 995 996 if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { 997 logit("Disabling %s authentication", authctxt->method->name); 998 authctxt->method->enabled = NULL; 999 /* Continue with an empty password to fail gracefully */ 1000 crypted = xstrdup(""); 1001 } 1002 1003 #ifdef JPAKE_DEBUG 1004 debug3("%s: salt = %s", __func__, salt); 1005 debug3("%s: scheme = %s", __func__, crypt_scheme); 1006 debug3("%s: crypted = %s", __func__, crypted); 1007 #endif 1008 1009 if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), 1010 &secret, &secret_len) != 0) 1011 fatal("%s: hash_buffer", __func__); 1012 1013 bzero(password, strlen(password)); 1014 bzero(crypted, strlen(crypted)); 1015 xfree(password); 1016 xfree(crypted); 1017 1018 if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) 1019 fatal("%s: BN_bin2bn (secret)", __func__); 1020 bzero(secret, secret_len); 1021 xfree(secret); 1022 1023 return ret; 1024 } 1025 1026 /* ARGSUSED */ 1027 void 1028 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) 1029 { 1030 Authctxt *authctxt = ctxt; 1031 struct jpake_ctx *pctx = authctxt->methoddata; 1032 u_char *x3_proof, *x4_proof, *x2_s_proof; 1033 u_int x3_proof_len, x4_proof_len, x2_s_proof_len; 1034 char *crypt_scheme, *salt; 1035 1036 /* Disable this message */ 1037 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); 1038 1039 if ((pctx->g_x3 = BN_new()) == NULL || 1040 (pctx->g_x4 = BN_new()) == NULL) 1041 fatal("%s: BN_new", __func__); 1042 1043 /* Fetch step 1 values */ 1044 crypt_scheme = packet_get_string(NULL); 1045 salt = packet_get_string(NULL); 1046 pctx->server_id = packet_get_string(&pctx->server_id_len); 1047 packet_get_bignum2(pctx->g_x3); 1048 packet_get_bignum2(pctx->g_x4); 1049 x3_proof = packet_get_string(&x3_proof_len); 1050 x4_proof = packet_get_string(&x4_proof_len); 1051 packet_check_eom(); 1052 1053 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); 1054 1055 /* Obtain password and derive secret */ 1056 pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); 1057 bzero(crypt_scheme, strlen(crypt_scheme)); 1058 bzero(salt, strlen(salt)); 1059 xfree(crypt_scheme); 1060 xfree(salt); 1061 JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); 1062 1063 /* Calculate step 2 values */ 1064 jpake_step2(pctx->grp, pctx->s, pctx->g_x1, 1065 pctx->g_x3, pctx->g_x4, pctx->x2, 1066 pctx->server_id, pctx->server_id_len, 1067 pctx->client_id, pctx->client_id_len, 1068 x3_proof, x3_proof_len, 1069 x4_proof, x4_proof_len, 1070 &pctx->a, 1071 &x2_s_proof, &x2_s_proof_len); 1072 1073 bzero(x3_proof, x3_proof_len); 1074 bzero(x4_proof, x4_proof_len); 1075 xfree(x3_proof); 1076 xfree(x4_proof); 1077 1078 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); 1079 1080 /* Send values for step 2 */ 1081 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); 1082 packet_put_bignum2(pctx->a); 1083 packet_put_string(x2_s_proof, x2_s_proof_len); 1084 packet_send(); 1085 1086 bzero(x2_s_proof, x2_s_proof_len); 1087 xfree(x2_s_proof); 1088 1089 /* Expect step 2 packet from peer */ 1090 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, 1091 input_userauth_jpake_server_step2); 1092 } 1093 1094 /* ARGSUSED */ 1095 void 1096 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) 1097 { 1098 Authctxt *authctxt = ctxt; 1099 struct jpake_ctx *pctx = authctxt->methoddata; 1100 u_char *x4_s_proof; 1101 u_int x4_s_proof_len; 1102 1103 /* Disable this message */ 1104 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); 1105 1106 if ((pctx->b = BN_new()) == NULL) 1107 fatal("%s: BN_new", __func__); 1108 1109 /* Fetch step 2 values */ 1110 packet_get_bignum2(pctx->b); 1111 x4_s_proof = packet_get_string(&x4_s_proof_len); 1112 packet_check_eom(); 1113 1114 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); 1115 1116 /* Derive shared key and calculate confirmation hash */ 1117 jpake_key_confirm(pctx->grp, pctx->s, pctx->b, 1118 pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, 1119 pctx->client_id, pctx->client_id_len, 1120 pctx->server_id, pctx->server_id_len, 1121 session_id2, session_id2_len, 1122 x4_s_proof, x4_s_proof_len, 1123 &pctx->k, 1124 &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); 1125 1126 bzero(x4_s_proof, x4_s_proof_len); 1127 xfree(x4_s_proof); 1128 1129 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); 1130 1131 /* Send key confirmation proof */ 1132 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); 1133 packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); 1134 packet_send(); 1135 1136 /* Expect confirmation from peer */ 1137 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, 1138 input_userauth_jpake_server_confirm); 1139 } 1140 1141 /* ARGSUSED */ 1142 void 1143 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) 1144 { 1145 Authctxt *authctxt = ctxt; 1146 struct jpake_ctx *pctx = authctxt->methoddata; 1147 1148 /* Disable this message */ 1149 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); 1150 1151 pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); 1152 packet_check_eom(); 1153 1154 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); 1155 1156 /* Verify expected confirmation hash */ 1157 if (jpake_check_confirm(pctx->k, 1158 pctx->server_id, pctx->server_id_len, 1159 session_id2, session_id2_len, 1160 pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) 1161 debug("%s: %s success", __func__, authctxt->method->name); 1162 else { 1163 debug("%s: confirmation mismatch", __func__); 1164 /* XXX stash this so if auth succeeds then we can warn/kill */ 1165 } 1166 1167 userauth_jpake_cleanup(authctxt); 1168 } 1169 #endif /* JPAKE */ 1170 1171 static int 1172 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 1173 u_char *data, u_int datalen) 1174 { 1175 Key *prv; 1176 int ret; 1177 1178 /* the agent supports this key */ 1179 if (id->ac) 1180 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 1181 data, datalen)); 1182 /* 1183 * we have already loaded the private key or 1184 * the private key is stored in external hardware 1185 */ 1186 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) 1187 return (key_sign(id->key, sigp, lenp, data, datalen)); 1188 /* load the private key from the file */ 1189 if ((prv = load_identity_file(id->filename)) == NULL) 1190 return (-1); 1191 ret = key_sign(prv, sigp, lenp, data, datalen); 1192 key_free(prv); 1193 return (ret); 1194 } 1195 1196 static int 1197 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1198 { 1199 Buffer b; 1200 u_char *blob, *signature; 1201 u_int bloblen, slen; 1202 u_int skip = 0; 1203 int ret = -1; 1204 int have_sig = 1; 1205 char *fp; 1206 1207 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 1208 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 1209 xfree(fp); 1210 1211 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1212 /* we cannot handle this key */ 1213 debug3("sign_and_send_pubkey: cannot handle key"); 1214 return 0; 1215 } 1216 /* data to be signed */ 1217 buffer_init(&b); 1218 if (datafellows & SSH_OLD_SESSIONID) { 1219 buffer_append(&b, session_id2, session_id2_len); 1220 skip = session_id2_len; 1221 } else { 1222 buffer_put_string(&b, session_id2, session_id2_len); 1223 skip = buffer_len(&b); 1224 } 1225 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1226 buffer_put_cstring(&b, authctxt->server_user); 1227 buffer_put_cstring(&b, 1228 datafellows & SSH_BUG_PKSERVICE ? 1229 "ssh-userauth" : 1230 authctxt->service); 1231 if (datafellows & SSH_BUG_PKAUTH) { 1232 buffer_put_char(&b, have_sig); 1233 } else { 1234 buffer_put_cstring(&b, authctxt->method->name); 1235 buffer_put_char(&b, have_sig); 1236 buffer_put_cstring(&b, key_ssh_name(id->key)); 1237 } 1238 buffer_put_string(&b, blob, bloblen); 1239 1240 /* generate signature */ 1241 ret = identity_sign(id, &signature, &slen, 1242 buffer_ptr(&b), buffer_len(&b)); 1243 if (ret == -1) { 1244 xfree(blob); 1245 buffer_free(&b); 1246 return 0; 1247 } 1248 #ifdef DEBUG_PK 1249 buffer_dump(&b); 1250 #endif 1251 if (datafellows & SSH_BUG_PKSERVICE) { 1252 buffer_clear(&b); 1253 buffer_append(&b, session_id2, session_id2_len); 1254 skip = session_id2_len; 1255 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1256 buffer_put_cstring(&b, authctxt->server_user); 1257 buffer_put_cstring(&b, authctxt->service); 1258 buffer_put_cstring(&b, authctxt->method->name); 1259 buffer_put_char(&b, have_sig); 1260 if (!(datafellows & SSH_BUG_PKAUTH)) 1261 buffer_put_cstring(&b, key_ssh_name(id->key)); 1262 buffer_put_string(&b, blob, bloblen); 1263 } 1264 xfree(blob); 1265 1266 /* append signature */ 1267 buffer_put_string(&b, signature, slen); 1268 xfree(signature); 1269 1270 /* skip session id and packet type */ 1271 if (buffer_len(&b) < skip + 1) 1272 fatal("userauth_pubkey: internal error"); 1273 buffer_consume(&b, skip + 1); 1274 1275 /* put remaining data from buffer into packet */ 1276 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1277 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1278 buffer_free(&b); 1279 packet_send(); 1280 1281 return 1; 1282 } 1283 1284 static int 1285 send_pubkey_test(Authctxt *authctxt, Identity *id) 1286 { 1287 u_char *blob; 1288 u_int bloblen, have_sig = 0; 1289 1290 debug3("send_pubkey_test"); 1291 1292 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1293 /* we cannot handle this key */ 1294 debug3("send_pubkey_test: cannot handle key"); 1295 return 0; 1296 } 1297 /* register callback for USERAUTH_PK_OK message */ 1298 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1299 1300 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1301 packet_put_cstring(authctxt->server_user); 1302 packet_put_cstring(authctxt->service); 1303 packet_put_cstring(authctxt->method->name); 1304 packet_put_char(have_sig); 1305 if (!(datafellows & SSH_BUG_PKAUTH)) 1306 packet_put_cstring(key_ssh_name(id->key)); 1307 packet_put_string(blob, bloblen); 1308 xfree(blob); 1309 packet_send(); 1310 return 1; 1311 } 1312 1313 static Key * 1314 load_identity_file(char *filename) 1315 { 1316 Key *private; 1317 char prompt[300], *passphrase; 1318 int perm_ok = 0, quit, i; 1319 struct stat st; 1320 1321 if (stat(filename, &st) < 0) { 1322 debug3("no such identity: %s", filename); 1323 return NULL; 1324 } 1325 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1326 if (!perm_ok) 1327 return NULL; 1328 if (private == NULL) { 1329 if (options.batch_mode) 1330 return NULL; 1331 snprintf(prompt, sizeof prompt, 1332 "Enter passphrase for key '%.100s': ", filename); 1333 for (i = 0; i < options.number_of_password_prompts; i++) { 1334 passphrase = read_passphrase(prompt, 0); 1335 if (strcmp(passphrase, "") != 0) { 1336 private = key_load_private_type(KEY_UNSPEC, 1337 filename, passphrase, NULL, NULL); 1338 quit = 0; 1339 } else { 1340 debug2("no passphrase given, try next key"); 1341 quit = 1; 1342 } 1343 memset(passphrase, 0, strlen(passphrase)); 1344 xfree(passphrase); 1345 if (private != NULL || quit) 1346 break; 1347 debug2("bad passphrase given, try again..."); 1348 } 1349 } 1350 return private; 1351 } 1352 1353 /* 1354 * try keys in the following order: 1355 * 1. agent keys that are found in the config file 1356 * 2. other agent keys 1357 * 3. keys that are only listed in the config file 1358 */ 1359 static void 1360 pubkey_prepare(Authctxt *authctxt) 1361 { 1362 Identity *id; 1363 Idlist agent, files, *preferred; 1364 Key *key; 1365 AuthenticationConnection *ac; 1366 char *comment; 1367 int i, found; 1368 1369 TAILQ_INIT(&agent); /* keys from the agent */ 1370 TAILQ_INIT(&files); /* keys from the config file */ 1371 preferred = &authctxt->keys; 1372 TAILQ_INIT(preferred); /* preferred order of keys */ 1373 1374 /* list of keys stored in the filesystem */ 1375 for (i = 0; i < options.num_identity_files; i++) { 1376 key = options.identity_keys[i]; 1377 if (key && key->type == KEY_RSA1) 1378 continue; 1379 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1380 continue; 1381 options.identity_keys[i] = NULL; 1382 id = xcalloc(1, sizeof(*id)); 1383 id->key = key; 1384 id->filename = xstrdup(options.identity_files[i]); 1385 TAILQ_INSERT_TAIL(&files, id, next); 1386 } 1387 /* list of keys supported by the agent */ 1388 if ((ac = ssh_get_authentication_connection())) { 1389 for (key = ssh_get_first_identity(ac, &comment, 2); 1390 key != NULL; 1391 key = ssh_get_next_identity(ac, &comment, 2)) { 1392 found = 0; 1393 TAILQ_FOREACH(id, &files, next) { 1394 /* agent keys from the config file are preferred */ 1395 if (key_equal(key, id->key)) { 1396 key_free(key); 1397 xfree(comment); 1398 TAILQ_REMOVE(&files, id, next); 1399 TAILQ_INSERT_TAIL(preferred, id, next); 1400 id->ac = ac; 1401 found = 1; 1402 break; 1403 } 1404 } 1405 if (!found && !options.identities_only) { 1406 id = xcalloc(1, sizeof(*id)); 1407 id->key = key; 1408 id->filename = comment; 1409 id->ac = ac; 1410 TAILQ_INSERT_TAIL(&agent, id, next); 1411 } 1412 } 1413 /* append remaining agent keys */ 1414 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1415 TAILQ_REMOVE(&agent, id, next); 1416 TAILQ_INSERT_TAIL(preferred, id, next); 1417 } 1418 authctxt->agent = ac; 1419 } 1420 /* append remaining keys from the config file */ 1421 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1422 TAILQ_REMOVE(&files, id, next); 1423 TAILQ_INSERT_TAIL(preferred, id, next); 1424 } 1425 TAILQ_FOREACH(id, preferred, next) { 1426 debug2("key: %s (%p)", id->filename, id->key); 1427 } 1428 } 1429 1430 static void 1431 pubkey_cleanup(Authctxt *authctxt) 1432 { 1433 Identity *id; 1434 1435 if (authctxt->agent != NULL) 1436 ssh_close_authentication_connection(authctxt->agent); 1437 for (id = TAILQ_FIRST(&authctxt->keys); id; 1438 id = TAILQ_FIRST(&authctxt->keys)) { 1439 TAILQ_REMOVE(&authctxt->keys, id, next); 1440 if (id->key) 1441 key_free(id->key); 1442 if (id->filename) 1443 xfree(id->filename); 1444 xfree(id); 1445 } 1446 } 1447 1448 int 1449 userauth_pubkey(Authctxt *authctxt) 1450 { 1451 Identity *id; 1452 int sent = 0; 1453 1454 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1455 if (id->tried++) 1456 return (0); 1457 /* move key to the end of the queue */ 1458 TAILQ_REMOVE(&authctxt->keys, id, next); 1459 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1460 /* 1461 * send a test message if we have the public key. for 1462 * encrypted keys we cannot do this and have to load the 1463 * private key instead 1464 */ 1465 if (id->key && id->key->type != KEY_RSA1) { 1466 debug("Offering %s public key: %s", key_type(id->key), 1467 id->filename); 1468 sent = send_pubkey_test(authctxt, id); 1469 } else if (id->key == NULL) { 1470 debug("Trying private key: %s", id->filename); 1471 id->key = load_identity_file(id->filename); 1472 if (id->key != NULL) { 1473 id->isprivate = 1; 1474 sent = sign_and_send_pubkey(authctxt, id); 1475 key_free(id->key); 1476 id->key = NULL; 1477 } 1478 } 1479 if (sent) 1480 return (sent); 1481 } 1482 return (0); 1483 } 1484 1485 /* 1486 * Send userauth request message specifying keyboard-interactive method. 1487 */ 1488 int 1489 userauth_kbdint(Authctxt *authctxt) 1490 { 1491 static int attempt = 0; 1492 1493 if (attempt++ >= options.number_of_password_prompts) 1494 return 0; 1495 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1496 if (attempt > 1 && !authctxt->info_req_seen) { 1497 debug3("userauth_kbdint: disable: no info_req_seen"); 1498 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1499 return 0; 1500 } 1501 1502 debug2("userauth_kbdint"); 1503 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1504 packet_put_cstring(authctxt->server_user); 1505 packet_put_cstring(authctxt->service); 1506 packet_put_cstring(authctxt->method->name); 1507 packet_put_cstring(""); /* lang */ 1508 packet_put_cstring(options.kbd_interactive_devices ? 1509 options.kbd_interactive_devices : ""); 1510 packet_send(); 1511 1512 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1513 return 1; 1514 } 1515 1516 /* 1517 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1518 */ 1519 void 1520 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1521 { 1522 Authctxt *authctxt = ctxt; 1523 char *name, *inst, *lang, *prompt, *response; 1524 u_int num_prompts, i; 1525 int echo = 0; 1526 1527 debug2("input_userauth_info_req"); 1528 1529 if (authctxt == NULL) 1530 fatal("input_userauth_info_req: no authentication context"); 1531 1532 authctxt->info_req_seen = 1; 1533 1534 name = packet_get_string(NULL); 1535 inst = packet_get_string(NULL); 1536 lang = packet_get_string(NULL); 1537 if (strlen(name) > 0) 1538 logit("%s", name); 1539 if (strlen(inst) > 0) 1540 logit("%s", inst); 1541 xfree(name); 1542 xfree(inst); 1543 xfree(lang); 1544 1545 num_prompts = packet_get_int(); 1546 /* 1547 * Begin to build info response packet based on prompts requested. 1548 * We commit to providing the correct number of responses, so if 1549 * further on we run into a problem that prevents this, we have to 1550 * be sure and clean this up and send a correct error response. 1551 */ 1552 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1553 packet_put_int(num_prompts); 1554 1555 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1556 for (i = 0; i < num_prompts; i++) { 1557 prompt = packet_get_string(NULL); 1558 echo = packet_get_char(); 1559 1560 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1561 1562 packet_put_cstring(response); 1563 memset(response, 0, strlen(response)); 1564 xfree(response); 1565 xfree(prompt); 1566 } 1567 packet_check_eom(); /* done with parsing incoming message. */ 1568 1569 packet_add_padding(64); 1570 packet_send(); 1571 } 1572 1573 static int 1574 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1575 u_char *data, u_int datalen) 1576 { 1577 Buffer b; 1578 struct stat st; 1579 pid_t pid; 1580 int to[2], from[2], status, version = 2; 1581 1582 debug2("ssh_keysign called"); 1583 1584 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1585 error("ssh_keysign: not installed: %s", strerror(errno)); 1586 return -1; 1587 } 1588 if (fflush(stdout) != 0) 1589 error("ssh_keysign: fflush: %s", strerror(errno)); 1590 if (pipe(to) < 0) { 1591 error("ssh_keysign: pipe: %s", strerror(errno)); 1592 return -1; 1593 } 1594 if (pipe(from) < 0) { 1595 error("ssh_keysign: pipe: %s", strerror(errno)); 1596 return -1; 1597 } 1598 if ((pid = fork()) < 0) { 1599 error("ssh_keysign: fork: %s", strerror(errno)); 1600 return -1; 1601 } 1602 if (pid == 0) { 1603 /* keep the socket on exec */ 1604 fcntl(packet_get_connection_in(), F_SETFD, 0); 1605 permanently_drop_suid(getuid()); 1606 close(from[0]); 1607 if (dup2(from[1], STDOUT_FILENO) < 0) 1608 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1609 close(to[1]); 1610 if (dup2(to[0], STDIN_FILENO) < 0) 1611 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1612 close(from[1]); 1613 close(to[0]); 1614 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1615 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1616 strerror(errno)); 1617 } 1618 close(from[1]); 1619 close(to[0]); 1620 1621 buffer_init(&b); 1622 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1623 buffer_put_string(&b, data, datalen); 1624 if (ssh_msg_send(to[1], version, &b) == -1) 1625 fatal("ssh_keysign: couldn't send request"); 1626 1627 if (ssh_msg_recv(from[0], &b) < 0) { 1628 error("ssh_keysign: no reply"); 1629 buffer_free(&b); 1630 return -1; 1631 } 1632 close(from[0]); 1633 close(to[1]); 1634 1635 while (waitpid(pid, &status, 0) < 0) 1636 if (errno != EINTR) 1637 break; 1638 1639 if (buffer_get_char(&b) != version) { 1640 error("ssh_keysign: bad version"); 1641 buffer_free(&b); 1642 return -1; 1643 } 1644 *sigp = buffer_get_string(&b, lenp); 1645 buffer_free(&b); 1646 1647 return 0; 1648 } 1649 1650 int 1651 userauth_hostbased(Authctxt *authctxt) 1652 { 1653 Key *private = NULL; 1654 Sensitive *sensitive = authctxt->sensitive; 1655 Buffer b; 1656 u_char *signature, *blob; 1657 char *chost, *pkalg, *p; 1658 const char *service; 1659 u_int blen, slen; 1660 int ok, i, found = 0; 1661 1662 /* check for a useful key */ 1663 for (i = 0; i < sensitive->nkeys; i++) { 1664 private = sensitive->keys[i]; 1665 if (private && private->type != KEY_RSA1) { 1666 found = 1; 1667 /* we take and free the key */ 1668 sensitive->keys[i] = NULL; 1669 break; 1670 } 1671 } 1672 if (!found) { 1673 debug("No more client hostkeys for hostbased authentication."); 1674 return 0; 1675 } 1676 if (key_to_blob(private, &blob, &blen) == 0) { 1677 key_free(private); 1678 return 0; 1679 } 1680 /* figure out a name for the client host */ 1681 p = get_local_name(packet_get_connection_in()); 1682 if (p == NULL) { 1683 error("userauth_hostbased: cannot get local ipaddr/name"); 1684 key_free(private); 1685 xfree(blob); 1686 return 0; 1687 } 1688 xasprintf(&chost, "%s.", p); 1689 debug2("userauth_hostbased: chost %s", chost); 1690 xfree(p); 1691 1692 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1693 authctxt->service; 1694 pkalg = xstrdup(key_ssh_name(private)); 1695 buffer_init(&b); 1696 /* construct data */ 1697 buffer_put_string(&b, session_id2, session_id2_len); 1698 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1699 buffer_put_cstring(&b, authctxt->server_user); 1700 buffer_put_cstring(&b, service); 1701 buffer_put_cstring(&b, authctxt->method->name); 1702 buffer_put_cstring(&b, pkalg); 1703 buffer_put_string(&b, blob, blen); 1704 buffer_put_cstring(&b, chost); 1705 buffer_put_cstring(&b, authctxt->local_user); 1706 #ifdef DEBUG_PK 1707 buffer_dump(&b); 1708 #endif 1709 if (sensitive->external_keysign) 1710 ok = ssh_keysign(private, &signature, &slen, 1711 buffer_ptr(&b), buffer_len(&b)); 1712 else 1713 ok = key_sign(private, &signature, &slen, 1714 buffer_ptr(&b), buffer_len(&b)); 1715 key_free(private); 1716 buffer_free(&b); 1717 if (ok != 0) { 1718 error("key_sign failed"); 1719 xfree(chost); 1720 xfree(pkalg); 1721 xfree(blob); 1722 return 0; 1723 } 1724 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1725 packet_put_cstring(authctxt->server_user); 1726 packet_put_cstring(authctxt->service); 1727 packet_put_cstring(authctxt->method->name); 1728 packet_put_cstring(pkalg); 1729 packet_put_string(blob, blen); 1730 packet_put_cstring(chost); 1731 packet_put_cstring(authctxt->local_user); 1732 packet_put_string(signature, slen); 1733 memset(signature, 's', slen); 1734 xfree(signature); 1735 xfree(chost); 1736 xfree(pkalg); 1737 xfree(blob); 1738 1739 packet_send(); 1740 return 1; 1741 } 1742 1743 #ifdef JPAKE 1744 int 1745 userauth_jpake(Authctxt *authctxt) 1746 { 1747 struct jpake_ctx *pctx; 1748 u_char *x1_proof, *x2_proof; 1749 u_int x1_proof_len, x2_proof_len; 1750 static int attempt = 0; /* XXX share with userauth_password's? */ 1751 1752 if (attempt++ >= options.number_of_password_prompts) 1753 return 0; 1754 if (attempt != 1) 1755 error("Permission denied, please try again."); 1756 1757 if (authctxt->methoddata != NULL) 1758 fatal("%s: authctxt->methoddata already set (%p)", 1759 __func__, authctxt->methoddata); 1760 1761 authctxt->methoddata = pctx = jpake_new(); 1762 1763 /* 1764 * Send request immediately, to get the protocol going while 1765 * we do the initial computations. 1766 */ 1767 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1768 packet_put_cstring(authctxt->server_user); 1769 packet_put_cstring(authctxt->service); 1770 packet_put_cstring(authctxt->method->name); 1771 packet_send(); 1772 packet_write_wait(); 1773 1774 jpake_step1(pctx->grp, 1775 &pctx->client_id, &pctx->client_id_len, 1776 &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, 1777 &x1_proof, &x1_proof_len, 1778 &x2_proof, &x2_proof_len); 1779 1780 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); 1781 1782 packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); 1783 packet_put_string(pctx->client_id, pctx->client_id_len); 1784 packet_put_bignum2(pctx->g_x1); 1785 packet_put_bignum2(pctx->g_x2); 1786 packet_put_string(x1_proof, x1_proof_len); 1787 packet_put_string(x2_proof, x2_proof_len); 1788 packet_send(); 1789 1790 bzero(x1_proof, x1_proof_len); 1791 bzero(x2_proof, x2_proof_len); 1792 xfree(x1_proof); 1793 xfree(x2_proof); 1794 1795 /* Expect step 1 packet from peer */ 1796 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, 1797 input_userauth_jpake_server_step1); 1798 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, 1799 &input_userauth_success_unexpected); 1800 1801 return 1; 1802 } 1803 1804 void 1805 userauth_jpake_cleanup(Authctxt *authctxt) 1806 { 1807 debug3("%s: clean up", __func__); 1808 if (authctxt->methoddata != NULL) { 1809 jpake_free(authctxt->methoddata); 1810 authctxt->methoddata = NULL; 1811 } 1812 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 1813 } 1814 #endif /* JPAKE */ 1815 1816 /* find auth method */ 1817 1818 /* 1819 * given auth method name, if configurable options permit this method fill 1820 * in auth_ident field and return true, otherwise return false. 1821 */ 1822 static int 1823 authmethod_is_enabled(Authmethod *method) 1824 { 1825 if (method == NULL) 1826 return 0; 1827 /* return false if options indicate this method is disabled */ 1828 if (method->enabled == NULL || *method->enabled == 0) 1829 return 0; 1830 /* return false if batch mode is enabled but method needs interactive mode */ 1831 if (method->batch_flag != NULL && *method->batch_flag != 0) 1832 return 0; 1833 return 1; 1834 } 1835 1836 static Authmethod * 1837 authmethod_lookup(const char *name) 1838 { 1839 Authmethod *method = NULL; 1840 if (name != NULL) 1841 for (method = authmethods; method->name != NULL; method++) 1842 if (strcmp(name, method->name) == 0) 1843 return method; 1844 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1845 return NULL; 1846 } 1847 1848 /* XXX internal state */ 1849 static Authmethod *current = NULL; 1850 static char *supported = NULL; 1851 static char *preferred = NULL; 1852 1853 /* 1854 * Given the authentication method list sent by the server, return the 1855 * next method we should try. If the server initially sends a nil list, 1856 * use a built-in default list. 1857 */ 1858 static Authmethod * 1859 authmethod_get(char *authlist) 1860 { 1861 char *name = NULL; 1862 u_int next; 1863 1864 /* Use a suitable default if we're passed a nil list. */ 1865 if (authlist == NULL || strlen(authlist) == 0) 1866 authlist = options.preferred_authentications; 1867 1868 if (supported == NULL || strcmp(authlist, supported) != 0) { 1869 debug3("start over, passed a different list %s", authlist); 1870 if (supported != NULL) 1871 xfree(supported); 1872 supported = xstrdup(authlist); 1873 preferred = options.preferred_authentications; 1874 debug3("preferred %s", preferred); 1875 current = NULL; 1876 } else if (current != NULL && authmethod_is_enabled(current)) 1877 return current; 1878 1879 for (;;) { 1880 if ((name = match_list(preferred, supported, &next)) == NULL) { 1881 debug("No more authentication methods to try."); 1882 current = NULL; 1883 return NULL; 1884 } 1885 preferred += next; 1886 debug3("authmethod_lookup %s", name); 1887 debug3("remaining preferred: %s", preferred); 1888 if ((current = authmethod_lookup(name)) != NULL && 1889 authmethod_is_enabled(current)) { 1890 debug3("authmethod_is_enabled %s", name); 1891 debug("Next authentication method: %s", name); 1892 xfree(name); 1893 return current; 1894 } 1895 } 1896 if (name != NULL) 1897 xfree(name); 1898 } 1899 1900 static char * 1901 authmethods_get(void) 1902 { 1903 Authmethod *method = NULL; 1904 Buffer b; 1905 char *list; 1906 1907 buffer_init(&b); 1908 for (method = authmethods; method->name != NULL; method++) { 1909 if (authmethod_is_enabled(method)) { 1910 if (buffer_len(&b) > 0) 1911 buffer_append(&b, ",", 1); 1912 buffer_append(&b, method->name, strlen(method->name)); 1913 } 1914 } 1915 buffer_append(&b, "\0", 1); 1916 list = xstrdup(buffer_ptr(&b)); 1917 buffer_free(&b); 1918 return list; 1919 } 1920 1921
