1 /* $OpenBSD: sshconnect2.c,v 1.210 2014/07/15 15:54:14 millert Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "hostfile.h" 67 68 #ifdef GSSAPI 69 #include "ssh-gss.h" 70 #endif 71 72 /* import */ 73 extern char *client_version_string; 74 extern char *server_version_string; 75 extern Options options; 76 77 /* 78 * SSH2 key exchange 79 */ 80 81 u_char *session_id2 = NULL; 82 u_int session_id2_len = 0; 83 84 char *xxx_host; 85 struct sockaddr *xxx_hostaddr; 86 87 Kex *xxx_kex = NULL; 88 89 static int 90 verify_host_key_callback(Key *hostkey) 91 { 92 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 93 fatal("Host key verification failed."); 94 return 0; 95 } 96 97 static char * 98 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 99 { 100 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 101 size_t maxlen; 102 struct hostkeys *hostkeys; 103 int ktype; 104 u_int i; 105 106 /* Find all hostkeys for this hostname */ 107 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 108 hostkeys = init_hostkeys(); 109 for (i = 0; i < options.num_user_hostfiles; i++) 110 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 111 for (i = 0; i < options.num_system_hostfiles; i++) 112 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 113 114 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 115 maxlen = strlen(avail) + 1; 116 first = xmalloc(maxlen); 117 last = xmalloc(maxlen); 118 *first = *last = '\0'; 119 120 #define ALG_APPEND(to, from) \ 121 do { \ 122 if (*to != '\0') \ 123 strlcat(to, ",", maxlen); \ 124 strlcat(to, from, maxlen); \ 125 } while (0) 126 127 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 128 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC) 129 fatal("%s: unknown alg %s", __func__, alg); 130 if (lookup_key_in_hostkeys_by_type(hostkeys, 131 key_type_plain(ktype), NULL)) 132 ALG_APPEND(first, alg); 133 else 134 ALG_APPEND(last, alg); 135 } 136 #undef ALG_APPEND 137 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last); 138 if (*first != '\0') 139 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 140 141 free(first); 142 free(last); 143 free(hostname); 144 free(oavail); 145 free_hostkeys(hostkeys); 146 147 return ret; 148 } 149 150 void 151 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 152 { 153 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 154 Kex *kex; 155 156 xxx_host = host; 157 xxx_hostaddr = hostaddr; 158 159 if (options.ciphers == (char *)-1) { 160 logit("No valid ciphers for protocol version 2 given, using defaults."); 161 options.ciphers = NULL; 162 } 163 if (options.ciphers != NULL) { 164 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 165 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 166 } 167 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 168 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 169 myproposal[PROPOSAL_ENC_ALGS_STOC] = 170 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 171 if (options.compression) { 172 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 173 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; 174 } else { 175 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 176 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; 177 } 178 if (options.macs != NULL) { 179 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 180 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 181 } 182 if (options.hostkeyalgorithms != NULL) 183 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 184 compat_pkalg_proposal(options.hostkeyalgorithms); 185 else { 186 /* Prefer algorithms that we already have keys for */ 187 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 188 compat_pkalg_proposal( 189 order_hostkeyalgs(host, hostaddr, port)); 190 } 191 if (options.kex_algorithms != NULL) 192 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 193 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 194 myproposal[PROPOSAL_KEX_ALGS]); 195 196 if (options.rekey_limit || options.rekey_interval) 197 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 198 (time_t)options.rekey_interval); 199 200 /* start key exchange */ 201 kex = kex_setup(myproposal); 202 #ifdef WITH_OPENSSL 203 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 204 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 205 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 206 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 207 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 208 #endif 209 kex->kex[KEX_C25519_SHA256] = kexc25519_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 int userprovided; 252 }; 253 TAILQ_HEAD(idlist, identity); 254 255 struct Authctxt { 256 const char *server_user; 257 const char *local_user; 258 const char *host; 259 const char *service; 260 Authmethod *method; 261 sig_atomic_t success; 262 char *authlist; 263 /* pubkey */ 264 Idlist keys; 265 AuthenticationConnection *agent; 266 /* hostbased */ 267 Sensitive *sensitive; 268 /* kbd-interactive */ 269 int info_req_seen; 270 /* generic */ 271 void *methoddata; 272 }; 273 struct Authmethod { 274 char *name; /* string to compare against server's list */ 275 int (*userauth)(Authctxt *authctxt); 276 void (*cleanup)(Authctxt *authctxt); 277 int *enabled; /* flag in option struct that enables method */ 278 int *batch_flag; /* flag in option struct that disables method */ 279 }; 280 281 void input_userauth_success(int, u_int32_t, void *); 282 void input_userauth_success_unexpected(int, u_int32_t, void *); 283 void input_userauth_failure(int, u_int32_t, void *); 284 void input_userauth_banner(int, u_int32_t, void *); 285 void input_userauth_error(int, u_int32_t, void *); 286 void input_userauth_info_req(int, u_int32_t, void *); 287 void input_userauth_pk_ok(int, u_int32_t, void *); 288 void input_userauth_passwd_changereq(int, u_int32_t, void *); 289 290 int userauth_none(Authctxt *); 291 int userauth_pubkey(Authctxt *); 292 int userauth_passwd(Authctxt *); 293 int userauth_kbdint(Authctxt *); 294 int userauth_hostbased(Authctxt *); 295 296 #ifdef GSSAPI 297 int userauth_gssapi(Authctxt *authctxt); 298 void input_gssapi_response(int type, u_int32_t, void *); 299 void input_gssapi_token(int type, u_int32_t, void *); 300 void input_gssapi_hash(int type, u_int32_t, void *); 301 void input_gssapi_error(int, u_int32_t, void *); 302 void input_gssapi_errtok(int, u_int32_t, void *); 303 #endif 304 305 void userauth(Authctxt *, char *); 306 307 static int sign_and_send_pubkey(Authctxt *, Identity *); 308 static void pubkey_prepare(Authctxt *); 309 static void pubkey_cleanup(Authctxt *); 310 static Key *load_identity_file(char *, int); 311 312 static Authmethod *authmethod_get(char *authlist); 313 static Authmethod *authmethod_lookup(const char *name); 314 static char *authmethods_get(void); 315 316 Authmethod authmethods[] = { 317 #ifdef GSSAPI 318 {"gssapi-with-mic", 319 userauth_gssapi, 320 NULL, 321 &options.gss_authentication, 322 NULL}, 323 #endif 324 {"hostbased", 325 userauth_hostbased, 326 NULL, 327 &options.hostbased_authentication, 328 NULL}, 329 {"publickey", 330 userauth_pubkey, 331 NULL, 332 &options.pubkey_authentication, 333 NULL}, 334 {"keyboard-interactive", 335 userauth_kbdint, 336 NULL, 337 &options.kbd_interactive_authentication, 338 &options.batch_mode}, 339 {"password", 340 userauth_passwd, 341 NULL, 342 &options.password_authentication, 343 &options.batch_mode}, 344 {"none", 345 userauth_none, 346 NULL, 347 NULL, 348 NULL}, 349 {NULL, NULL, NULL, NULL, NULL} 350 }; 351 352 void 353 ssh_userauth2(const char *local_user, const char *server_user, char *host, 354 Sensitive *sensitive) 355 { 356 Authctxt authctxt; 357 int type; 358 359 if (options.challenge_response_authentication) 360 options.kbd_interactive_authentication = 1; 361 362 packet_start(SSH2_MSG_SERVICE_REQUEST); 363 packet_put_cstring("ssh-userauth"); 364 packet_send(); 365 debug("SSH2_MSG_SERVICE_REQUEST sent"); 366 packet_write_wait(); 367 type = packet_read(); 368 if (type != SSH2_MSG_SERVICE_ACCEPT) 369 fatal("Server denied authentication request: %d", type); 370 if (packet_remaining() > 0) { 371 char *reply = packet_get_string(NULL); 372 debug2("service_accept: %s", reply); 373 free(reply); 374 } else { 375 debug2("buggy server: service_accept w/o service"); 376 } 377 packet_check_eom(); 378 debug("SSH2_MSG_SERVICE_ACCEPT received"); 379 380 if (options.preferred_authentications == NULL) 381 options.preferred_authentications = authmethods_get(); 382 383 /* setup authentication context */ 384 memset(&authctxt, 0, sizeof(authctxt)); 385 pubkey_prepare(&authctxt); 386 authctxt.server_user = server_user; 387 authctxt.local_user = local_user; 388 authctxt.host = host; 389 authctxt.service = "ssh-connection"; /* service name */ 390 authctxt.success = 0; 391 authctxt.method = authmethod_lookup("none"); 392 authctxt.authlist = NULL; 393 authctxt.methoddata = NULL; 394 authctxt.sensitive = sensitive; 395 authctxt.info_req_seen = 0; 396 if (authctxt.method == NULL) 397 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 398 399 /* initial userauth request */ 400 userauth_none(&authctxt); 401 402 dispatch_init(&input_userauth_error); 403 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 404 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 405 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 406 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ 407 408 pubkey_cleanup(&authctxt); 409 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 410 411 debug("Authentication succeeded (%s).", authctxt.method->name); 412 } 413 414 void 415 userauth(Authctxt *authctxt, char *authlist) 416 { 417 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 418 authctxt->method->cleanup(authctxt); 419 420 free(authctxt->methoddata); 421 authctxt->methoddata = NULL; 422 if (authlist == NULL) { 423 authlist = authctxt->authlist; 424 } else { 425 free(authctxt->authlist); 426 authctxt->authlist = authlist; 427 } 428 for (;;) { 429 Authmethod *method = authmethod_get(authlist); 430 if (method == NULL) 431 fatal("Permission denied (%s).", authlist); 432 authctxt->method = method; 433 434 /* reset the per method handler */ 435 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 436 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 437 438 /* and try new method */ 439 if (method->userauth(authctxt) != 0) { 440 debug2("we sent a %s packet, wait for reply", method->name); 441 break; 442 } else { 443 debug2("we did not send a packet, disable method"); 444 method->enabled = NULL; 445 } 446 } 447 } 448 449 /* ARGSUSED */ 450 void 451 input_userauth_error(int type, u_int32_t seq, void *ctxt) 452 { 453 fatal("input_userauth_error: bad message during authentication: " 454 "type %d", type); 455 } 456 457 /* ARGSUSED */ 458 void 459 input_userauth_banner(int type, u_int32_t seq, void *ctxt) 460 { 461 char *msg, *raw, *lang; 462 u_int len; 463 464 debug3("input_userauth_banner"); 465 raw = packet_get_string(&len); 466 lang = packet_get_string(NULL); 467 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) { 468 if (len > 65536) 469 len = 65536; 470 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */ 471 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH); 472 fprintf(stderr, "%s", msg); 473 free(msg); 474 } 475 free(raw); 476 free(lang); 477 } 478 479 /* ARGSUSED */ 480 void 481 input_userauth_success(int type, u_int32_t seq, void *ctxt) 482 { 483 Authctxt *authctxt = ctxt; 484 485 if (authctxt == NULL) 486 fatal("input_userauth_success: no authentication context"); 487 free(authctxt->authlist); 488 authctxt->authlist = NULL; 489 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 490 authctxt->method->cleanup(authctxt); 491 free(authctxt->methoddata); 492 authctxt->methoddata = NULL; 493 authctxt->success = 1; /* break out */ 494 } 495 496 void 497 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt) 498 { 499 Authctxt *authctxt = ctxt; 500 501 if (authctxt == NULL) 502 fatal("%s: no authentication context", __func__); 503 504 fatal("Unexpected authentication success during %s.", 505 authctxt->method->name); 506 } 507 508 /* ARGSUSED */ 509 void 510 input_userauth_failure(int type, u_int32_t seq, void *ctxt) 511 { 512 Authctxt *authctxt = ctxt; 513 char *authlist = NULL; 514 int partial; 515 516 if (authctxt == NULL) 517 fatal("input_userauth_failure: no authentication context"); 518 519 authlist = packet_get_string(NULL); 520 partial = packet_get_char(); 521 packet_check_eom(); 522 523 if (partial != 0) { 524 logit("Authenticated with partial success."); 525 /* reset state */ 526 pubkey_cleanup(authctxt); 527 pubkey_prepare(authctxt); 528 } 529 debug("Authentications that can continue: %s", authlist); 530 531 userauth(authctxt, authlist); 532 } 533 534 /* ARGSUSED */ 535 void 536 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) 537 { 538 Authctxt *authctxt = ctxt; 539 Key *key = NULL; 540 Identity *id = NULL; 541 Buffer b; 542 int pktype, sent = 0; 543 u_int alen, blen; 544 char *pkalg, *fp; 545 u_char *pkblob; 546 547 if (authctxt == NULL) 548 fatal("input_userauth_pk_ok: no authentication context"); 549 if (datafellows & SSH_BUG_PKOK) { 550 /* this is similar to SSH_BUG_PKAUTH */ 551 debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); 552 pkblob = packet_get_string(&blen); 553 buffer_init(&b); 554 buffer_append(&b, pkblob, blen); 555 pkalg = buffer_get_string(&b, &alen); 556 buffer_free(&b); 557 } else { 558 pkalg = packet_get_string(&alen); 559 pkblob = packet_get_string(&blen); 560 } 561 packet_check_eom(); 562 563 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 564 565 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 566 debug("unknown pkalg %s", pkalg); 567 goto done; 568 } 569 if ((key = key_from_blob(pkblob, blen)) == NULL) { 570 debug("no key from blob. pkalg %s", pkalg); 571 goto done; 572 } 573 if (key->type != pktype) { 574 error("input_userauth_pk_ok: type mismatch " 575 "for decoded key (received %d, expected %d)", 576 key->type, pktype); 577 goto done; 578 } 579 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 580 debug2("input_userauth_pk_ok: fp %s", fp); 581 free(fp); 582 583 /* 584 * search keys in the reverse order, because last candidate has been 585 * moved to the end of the queue. this also avoids confusion by 586 * duplicate keys 587 */ 588 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 589 if (key_equal(key, id->key)) { 590 sent = sign_and_send_pubkey(authctxt, id); 591 break; 592 } 593 } 594 done: 595 if (key != NULL) 596 key_free(key); 597 free(pkalg); 598 free(pkblob); 599 600 /* try another method if we did not send a packet */ 601 if (sent == 0) 602 userauth(authctxt, NULL); 603 } 604 605 #ifdef GSSAPI 606 int 607 userauth_gssapi(Authctxt *authctxt) 608 { 609 Gssctxt *gssctxt = NULL; 610 static gss_OID_set gss_supported = NULL; 611 static u_int mech = 0; 612 OM_uint32 min; 613 int ok = 0; 614 615 /* Try one GSSAPI method at a time, rather than sending them all at 616 * once. */ 617 618 if (gss_supported == NULL) 619 gss_indicate_mechs(&min, &gss_supported); 620 621 /* Check to see if the mechanism is usable before we offer it */ 622 while (mech < gss_supported->count && !ok) { 623 /* My DER encoding requires length<128 */ 624 if (gss_supported->elements[mech].length < 128 && 625 ssh_gssapi_check_mechanism(&gssctxt, 626 &gss_supported->elements[mech], authctxt->host)) { 627 ok = 1; /* Mechanism works */ 628 } else { 629 mech++; 630 } 631 } 632 633 if (!ok) 634 return 0; 635 636 authctxt->methoddata=(void *)gssctxt; 637 638 packet_start(SSH2_MSG_USERAUTH_REQUEST); 639 packet_put_cstring(authctxt->server_user); 640 packet_put_cstring(authctxt->service); 641 packet_put_cstring(authctxt->method->name); 642 643 packet_put_int(1); 644 645 packet_put_int((gss_supported->elements[mech].length) + 2); 646 packet_put_char(SSH_GSS_OIDTYPE); 647 packet_put_char(gss_supported->elements[mech].length); 648 packet_put_raw(gss_supported->elements[mech].elements, 649 gss_supported->elements[mech].length); 650 651 packet_send(); 652 653 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 654 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 655 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 656 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 657 658 mech++; /* Move along to next candidate */ 659 660 return 1; 661 } 662 663 static OM_uint32 664 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) 665 { 666 Authctxt *authctxt = ctxt; 667 Gssctxt *gssctxt = authctxt->methoddata; 668 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 669 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 670 gss_buffer_desc gssbuf; 671 OM_uint32 status, ms, flags; 672 Buffer b; 673 674 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 675 recv_tok, &send_tok, &flags); 676 677 if (send_tok.length > 0) { 678 if (GSS_ERROR(status)) 679 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 680 else 681 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 682 683 packet_put_string(send_tok.value, send_tok.length); 684 packet_send(); 685 gss_release_buffer(&ms, &send_tok); 686 } 687 688 if (status == GSS_S_COMPLETE) { 689 /* send either complete or MIC, depending on mechanism */ 690 if (!(flags & GSS_C_INTEG_FLAG)) { 691 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 692 packet_send(); 693 } else { 694 ssh_gssapi_buildmic(&b, authctxt->server_user, 695 authctxt->service, "gssapi-with-mic"); 696 697 gssbuf.value = buffer_ptr(&b); 698 gssbuf.length = buffer_len(&b); 699 700 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 701 702 if (!GSS_ERROR(status)) { 703 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 704 packet_put_string(mic.value, mic.length); 705 706 packet_send(); 707 } 708 709 buffer_free(&b); 710 gss_release_buffer(&ms, &mic); 711 } 712 } 713 714 return status; 715 } 716 717 /* ARGSUSED */ 718 void 719 input_gssapi_response(int type, u_int32_t plen, void *ctxt) 720 { 721 Authctxt *authctxt = ctxt; 722 Gssctxt *gssctxt; 723 int oidlen; 724 char *oidv; 725 726 if (authctxt == NULL) 727 fatal("input_gssapi_response: no authentication context"); 728 gssctxt = authctxt->methoddata; 729 730 /* Setup our OID */ 731 oidv = packet_get_string(&oidlen); 732 733 if (oidlen <= 2 || 734 oidv[0] != SSH_GSS_OIDTYPE || 735 oidv[1] != oidlen - 2) { 736 free(oidv); 737 debug("Badly encoded mechanism OID received"); 738 userauth(authctxt, NULL); 739 return; 740 } 741 742 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 743 fatal("Server returned different OID than expected"); 744 745 packet_check_eom(); 746 747 free(oidv); 748 749 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { 750 /* Start again with next method on list */ 751 debug("Trying to start again"); 752 userauth(authctxt, NULL); 753 return; 754 } 755 } 756 757 /* ARGSUSED */ 758 void 759 input_gssapi_token(int type, u_int32_t plen, void *ctxt) 760 { 761 Authctxt *authctxt = ctxt; 762 gss_buffer_desc recv_tok; 763 OM_uint32 status; 764 u_int slen; 765 766 if (authctxt == NULL) 767 fatal("input_gssapi_response: no authentication context"); 768 769 recv_tok.value = packet_get_string(&slen); 770 recv_tok.length = slen; /* safe typecast */ 771 772 packet_check_eom(); 773 774 status = process_gssapi_token(ctxt, &recv_tok); 775 776 free(recv_tok.value); 777 778 if (GSS_ERROR(status)) { 779 /* Start again with the next method in the list */ 780 userauth(authctxt, NULL); 781 return; 782 } 783 } 784 785 /* ARGSUSED */ 786 void 787 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 788 { 789 Authctxt *authctxt = ctxt; 790 Gssctxt *gssctxt; 791 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 792 gss_buffer_desc recv_tok; 793 OM_uint32 ms; 794 u_int len; 795 796 if (authctxt == NULL) 797 fatal("input_gssapi_response: no authentication context"); 798 gssctxt = authctxt->methoddata; 799 800 recv_tok.value = packet_get_string(&len); 801 recv_tok.length = len; 802 803 packet_check_eom(); 804 805 /* Stick it into GSSAPI and see what it says */ 806 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 807 &recv_tok, &send_tok, NULL); 808 809 free(recv_tok.value); 810 gss_release_buffer(&ms, &send_tok); 811 812 /* Server will be returning a failed packet after this one */ 813 } 814 815 /* ARGSUSED */ 816 void 817 input_gssapi_error(int type, u_int32_t plen, void *ctxt) 818 { 819 char *msg; 820 char *lang; 821 822 /* maj */(void)packet_get_int(); 823 /* min */(void)packet_get_int(); 824 msg=packet_get_string(NULL); 825 lang=packet_get_string(NULL); 826 827 packet_check_eom(); 828 829 debug("Server GSSAPI Error:\n%s", msg); 830 free(msg); 831 free(lang); 832 } 833 #endif /* GSSAPI */ 834 835 int 836 userauth_none(Authctxt *authctxt) 837 { 838 /* initial userauth request */ 839 packet_start(SSH2_MSG_USERAUTH_REQUEST); 840 packet_put_cstring(authctxt->server_user); 841 packet_put_cstring(authctxt->service); 842 packet_put_cstring(authctxt->method->name); 843 packet_send(); 844 return 1; 845 } 846 847 int 848 userauth_passwd(Authctxt *authctxt) 849 { 850 static int attempt = 0; 851 char prompt[150]; 852 char *password; 853 const char *host = options.host_key_alias ? options.host_key_alias : 854 authctxt->host; 855 856 if (attempt++ >= options.number_of_password_prompts) 857 return 0; 858 859 if (attempt != 1) 860 error("Permission denied, please try again."); 861 862 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 863 authctxt->server_user, host); 864 password = read_passphrase(prompt, 0); 865 packet_start(SSH2_MSG_USERAUTH_REQUEST); 866 packet_put_cstring(authctxt->server_user); 867 packet_put_cstring(authctxt->service); 868 packet_put_cstring(authctxt->method->name); 869 packet_put_char(0); 870 packet_put_cstring(password); 871 explicit_bzero(password, strlen(password)); 872 free(password); 873 packet_add_padding(64); 874 packet_send(); 875 876 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 877 &input_userauth_passwd_changereq); 878 879 return 1; 880 } 881 882 /* 883 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 884 */ 885 /* ARGSUSED */ 886 void 887 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) 888 { 889 Authctxt *authctxt = ctxt; 890 char *info, *lang, *password = NULL, *retype = NULL; 891 char prompt[150]; 892 const char *host = options.host_key_alias ? options.host_key_alias : 893 authctxt->host; 894 895 debug2("input_userauth_passwd_changereq"); 896 897 if (authctxt == NULL) 898 fatal("input_userauth_passwd_changereq: " 899 "no authentication context"); 900 901 info = packet_get_string(NULL); 902 lang = packet_get_string(NULL); 903 if (strlen(info) > 0) 904 logit("%s", info); 905 free(info); 906 free(lang); 907 packet_start(SSH2_MSG_USERAUTH_REQUEST); 908 packet_put_cstring(authctxt->server_user); 909 packet_put_cstring(authctxt->service); 910 packet_put_cstring(authctxt->method->name); 911 packet_put_char(1); /* additional info */ 912 snprintf(prompt, sizeof(prompt), 913 "Enter %.30s@%.128s's old password: ", 914 authctxt->server_user, host); 915 password = read_passphrase(prompt, 0); 916 packet_put_cstring(password); 917 explicit_bzero(password, strlen(password)); 918 free(password); 919 password = NULL; 920 while (password == NULL) { 921 snprintf(prompt, sizeof(prompt), 922 "Enter %.30s@%.128s's new password: ", 923 authctxt->server_user, host); 924 password = read_passphrase(prompt, RP_ALLOW_EOF); 925 if (password == NULL) { 926 /* bail out */ 927 return; 928 } 929 snprintf(prompt, sizeof(prompt), 930 "Retype %.30s@%.128s's new password: ", 931 authctxt->server_user, host); 932 retype = read_passphrase(prompt, 0); 933 if (strcmp(password, retype) != 0) { 934 explicit_bzero(password, strlen(password)); 935 free(password); 936 logit("Mismatch; try again, EOF to quit."); 937 password = NULL; 938 } 939 explicit_bzero(retype, strlen(retype)); 940 free(retype); 941 } 942 packet_put_cstring(password); 943 explicit_bzero(password, strlen(password)); 944 free(password); 945 packet_add_padding(64); 946 packet_send(); 947 948 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 949 &input_userauth_passwd_changereq); 950 } 951 952 static int 953 identity_sign(Identity *id, u_char **sigp, u_int *lenp, 954 u_char *data, u_int datalen) 955 { 956 Key *prv; 957 int ret; 958 959 /* the agent supports this key */ 960 if (id->ac) 961 return (ssh_agent_sign(id->ac, id->key, sigp, lenp, 962 data, datalen)); 963 /* 964 * we have already loaded the private key or 965 * the private key is stored in external hardware 966 */ 967 if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)) 968 return (key_sign(id->key, sigp, lenp, data, datalen)); 969 /* load the private key from the file */ 970 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL) 971 return (-1); 972 ret = key_sign(prv, sigp, lenp, data, datalen); 973 key_free(prv); 974 return (ret); 975 } 976 977 static int 978 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 979 { 980 Buffer b; 981 u_char *blob, *signature; 982 u_int bloblen, slen; 983 u_int skip = 0; 984 int ret = -1; 985 int have_sig = 1; 986 char *fp; 987 988 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); 989 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp); 990 free(fp); 991 992 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 993 /* we cannot handle this key */ 994 debug3("sign_and_send_pubkey: cannot handle key"); 995 return 0; 996 } 997 /* data to be signed */ 998 buffer_init(&b); 999 if (datafellows & SSH_OLD_SESSIONID) { 1000 buffer_append(&b, session_id2, session_id2_len); 1001 skip = session_id2_len; 1002 } else { 1003 buffer_put_string(&b, session_id2, session_id2_len); 1004 skip = buffer_len(&b); 1005 } 1006 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1007 buffer_put_cstring(&b, authctxt->server_user); 1008 buffer_put_cstring(&b, 1009 datafellows & SSH_BUG_PKSERVICE ? 1010 "ssh-userauth" : 1011 authctxt->service); 1012 if (datafellows & SSH_BUG_PKAUTH) { 1013 buffer_put_char(&b, have_sig); 1014 } else { 1015 buffer_put_cstring(&b, authctxt->method->name); 1016 buffer_put_char(&b, have_sig); 1017 buffer_put_cstring(&b, key_ssh_name(id->key)); 1018 } 1019 buffer_put_string(&b, blob, bloblen); 1020 1021 /* generate signature */ 1022 ret = identity_sign(id, &signature, &slen, 1023 buffer_ptr(&b), buffer_len(&b)); 1024 if (ret == -1) { 1025 free(blob); 1026 buffer_free(&b); 1027 return 0; 1028 } 1029 #ifdef DEBUG_PK 1030 buffer_dump(&b); 1031 #endif 1032 if (datafellows & SSH_BUG_PKSERVICE) { 1033 buffer_clear(&b); 1034 buffer_append(&b, session_id2, session_id2_len); 1035 skip = session_id2_len; 1036 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1037 buffer_put_cstring(&b, authctxt->server_user); 1038 buffer_put_cstring(&b, authctxt->service); 1039 buffer_put_cstring(&b, authctxt->method->name); 1040 buffer_put_char(&b, have_sig); 1041 if (!(datafellows & SSH_BUG_PKAUTH)) 1042 buffer_put_cstring(&b, key_ssh_name(id->key)); 1043 buffer_put_string(&b, blob, bloblen); 1044 } 1045 free(blob); 1046 1047 /* append signature */ 1048 buffer_put_string(&b, signature, slen); 1049 free(signature); 1050 1051 /* skip session id and packet type */ 1052 if (buffer_len(&b) < skip + 1) 1053 fatal("userauth_pubkey: internal error"); 1054 buffer_consume(&b, skip + 1); 1055 1056 /* put remaining data from buffer into packet */ 1057 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1058 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1059 buffer_free(&b); 1060 packet_send(); 1061 1062 return 1; 1063 } 1064 1065 static int 1066 send_pubkey_test(Authctxt *authctxt, Identity *id) 1067 { 1068 u_char *blob; 1069 u_int bloblen, have_sig = 0; 1070 1071 debug3("send_pubkey_test"); 1072 1073 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1074 /* we cannot handle this key */ 1075 debug3("send_pubkey_test: cannot handle key"); 1076 return 0; 1077 } 1078 /* register callback for USERAUTH_PK_OK message */ 1079 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1080 1081 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1082 packet_put_cstring(authctxt->server_user); 1083 packet_put_cstring(authctxt->service); 1084 packet_put_cstring(authctxt->method->name); 1085 packet_put_char(have_sig); 1086 if (!(datafellows & SSH_BUG_PKAUTH)) 1087 packet_put_cstring(key_ssh_name(id->key)); 1088 packet_put_string(blob, bloblen); 1089 free(blob); 1090 packet_send(); 1091 return 1; 1092 } 1093 1094 static Key * 1095 load_identity_file(char *filename, int userprovided) 1096 { 1097 Key *private; 1098 char prompt[300], *passphrase; 1099 int perm_ok = 0, quit, i; 1100 struct stat st; 1101 1102 if (stat(filename, &st) < 0) { 1103 (userprovided ? logit : debug3)("no such identity: %s: %s", 1104 filename, strerror(errno)); 1105 return NULL; 1106 } 1107 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); 1108 if (!perm_ok) { 1109 if (private != NULL) 1110 key_free(private); 1111 return NULL; 1112 } 1113 if (private == NULL) { 1114 if (options.batch_mode) 1115 return NULL; 1116 snprintf(prompt, sizeof prompt, 1117 "Enter passphrase for key '%.100s': ", filename); 1118 for (i = 0; i < options.number_of_password_prompts; i++) { 1119 passphrase = read_passphrase(prompt, 0); 1120 if (strcmp(passphrase, "") != 0) { 1121 private = key_load_private_type(KEY_UNSPEC, 1122 filename, passphrase, NULL, NULL); 1123 quit = 0; 1124 } else { 1125 debug2("no passphrase given, try next key"); 1126 quit = 1; 1127 } 1128 explicit_bzero(passphrase, strlen(passphrase)); 1129 free(passphrase); 1130 if (private != NULL || quit) 1131 break; 1132 debug2("bad passphrase given, try again..."); 1133 } 1134 } 1135 return private; 1136 } 1137 1138 /* 1139 * try keys in the following order: 1140 * 1. agent keys that are found in the config file 1141 * 2. other agent keys 1142 * 3. keys that are only listed in the config file 1143 */ 1144 static void 1145 pubkey_prepare(Authctxt *authctxt) 1146 { 1147 Identity *id, *id2, *tmp; 1148 Idlist agent, files, *preferred; 1149 Key *key; 1150 AuthenticationConnection *ac; 1151 char *comment; 1152 int i, found; 1153 1154 TAILQ_INIT(&agent); /* keys from the agent */ 1155 TAILQ_INIT(&files); /* keys from the config file */ 1156 preferred = &authctxt->keys; 1157 TAILQ_INIT(preferred); /* preferred order of keys */ 1158 1159 /* list of keys stored in the filesystem and PKCS#11 */ 1160 for (i = 0; i < options.num_identity_files; i++) { 1161 key = options.identity_keys[i]; 1162 if (key && key->type == KEY_RSA1) 1163 continue; 1164 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1165 continue; 1166 options.identity_keys[i] = NULL; 1167 id = xcalloc(1, sizeof(*id)); 1168 id->key = key; 1169 id->filename = xstrdup(options.identity_files[i]); 1170 id->userprovided = options.identity_file_userprovided[i]; 1171 TAILQ_INSERT_TAIL(&files, id, next); 1172 } 1173 /* Prefer PKCS11 keys that are explicitly listed */ 1174 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1175 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1176 continue; 1177 found = 0; 1178 TAILQ_FOREACH(id2, &files, next) { 1179 if (id2->key == NULL || 1180 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1181 continue; 1182 if (key_equal(id->key, id2->key)) { 1183 TAILQ_REMOVE(&files, id, next); 1184 TAILQ_INSERT_TAIL(preferred, id, next); 1185 found = 1; 1186 break; 1187 } 1188 } 1189 /* If IdentitiesOnly set and key not found then don't use it */ 1190 if (!found && options.identities_only) { 1191 TAILQ_REMOVE(&files, id, next); 1192 explicit_bzero(id, sizeof(*id)); 1193 free(id); 1194 } 1195 } 1196 /* list of keys supported by the agent */ 1197 if ((ac = ssh_get_authentication_connection())) { 1198 for (key = ssh_get_first_identity(ac, &comment, 2); 1199 key != NULL; 1200 key = ssh_get_next_identity(ac, &comment, 2)) { 1201 found = 0; 1202 TAILQ_FOREACH(id, &files, next) { 1203 /* agent keys from the config file are preferred */ 1204 if (key_equal(key, id->key)) { 1205 key_free(key); 1206 free(comment); 1207 TAILQ_REMOVE(&files, id, next); 1208 TAILQ_INSERT_TAIL(preferred, id, next); 1209 id->ac = ac; 1210 found = 1; 1211 break; 1212 } 1213 } 1214 if (!found && !options.identities_only) { 1215 id = xcalloc(1, sizeof(*id)); 1216 id->key = key; 1217 id->filename = comment; 1218 id->ac = ac; 1219 TAILQ_INSERT_TAIL(&agent, id, next); 1220 } 1221 } 1222 /* append remaining agent keys */ 1223 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1224 TAILQ_REMOVE(&agent, id, next); 1225 TAILQ_INSERT_TAIL(preferred, id, next); 1226 } 1227 authctxt->agent = ac; 1228 } 1229 /* append remaining keys from the config file */ 1230 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1231 TAILQ_REMOVE(&files, id, next); 1232 TAILQ_INSERT_TAIL(preferred, id, next); 1233 } 1234 TAILQ_FOREACH(id, preferred, next) { 1235 debug2("key: %s (%p),%s", id->filename, id->key, 1236 id->userprovided ? " explicit" : ""); 1237 } 1238 } 1239 1240 static void 1241 pubkey_cleanup(Authctxt *authctxt) 1242 { 1243 Identity *id; 1244 1245 if (authctxt->agent != NULL) 1246 ssh_close_authentication_connection(authctxt->agent); 1247 for (id = TAILQ_FIRST(&authctxt->keys); id; 1248 id = TAILQ_FIRST(&authctxt->keys)) { 1249 TAILQ_REMOVE(&authctxt->keys, id, next); 1250 if (id->key) 1251 key_free(id->key); 1252 free(id->filename); 1253 free(id); 1254 } 1255 } 1256 1257 int 1258 userauth_pubkey(Authctxt *authctxt) 1259 { 1260 Identity *id; 1261 int sent = 0; 1262 1263 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1264 if (id->tried++) 1265 return (0); 1266 /* move key to the end of the queue */ 1267 TAILQ_REMOVE(&authctxt->keys, id, next); 1268 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1269 /* 1270 * send a test message if we have the public key. for 1271 * encrypted keys we cannot do this and have to load the 1272 * private key instead 1273 */ 1274 if (id->key != NULL) { 1275 if (key_type_plain(id->key->type) == KEY_RSA && 1276 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1277 debug("Skipped %s key %s for RSA/MD5 server", 1278 key_type(id->key), id->filename); 1279 } else if (id->key->type != KEY_RSA1) { 1280 debug("Offering %s public key: %s", 1281 key_type(id->key), id->filename); 1282 sent = send_pubkey_test(authctxt, id); 1283 } 1284 } else { 1285 debug("Trying private key: %s", id->filename); 1286 id->key = load_identity_file(id->filename, 1287 id->userprovided); 1288 if (id->key != NULL) { 1289 id->isprivate = 1; 1290 if (key_type_plain(id->key->type) == KEY_RSA && 1291 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1292 debug("Skipped %s key %s for RSA/MD5 " 1293 "server", key_type(id->key), 1294 id->filename); 1295 } else { 1296 sent = sign_and_send_pubkey( 1297 authctxt, id); 1298 } 1299 key_free(id->key); 1300 id->key = NULL; 1301 } 1302 } 1303 if (sent) 1304 return (sent); 1305 } 1306 return (0); 1307 } 1308 1309 /* 1310 * Send userauth request message specifying keyboard-interactive method. 1311 */ 1312 int 1313 userauth_kbdint(Authctxt *authctxt) 1314 { 1315 static int attempt = 0; 1316 1317 if (attempt++ >= options.number_of_password_prompts) 1318 return 0; 1319 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1320 if (attempt > 1 && !authctxt->info_req_seen) { 1321 debug3("userauth_kbdint: disable: no info_req_seen"); 1322 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1323 return 0; 1324 } 1325 1326 debug2("userauth_kbdint"); 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_cstring(""); /* lang */ 1332 packet_put_cstring(options.kbd_interactive_devices ? 1333 options.kbd_interactive_devices : ""); 1334 packet_send(); 1335 1336 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1337 return 1; 1338 } 1339 1340 /* 1341 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1342 */ 1343 void 1344 input_userauth_info_req(int type, u_int32_t seq, void *ctxt) 1345 { 1346 Authctxt *authctxt = ctxt; 1347 char *name, *inst, *lang, *prompt, *response; 1348 u_int num_prompts, i; 1349 int echo = 0; 1350 1351 debug2("input_userauth_info_req"); 1352 1353 if (authctxt == NULL) 1354 fatal("input_userauth_info_req: no authentication context"); 1355 1356 authctxt->info_req_seen = 1; 1357 1358 name = packet_get_string(NULL); 1359 inst = packet_get_string(NULL); 1360 lang = packet_get_string(NULL); 1361 if (strlen(name) > 0) 1362 logit("%s", name); 1363 if (strlen(inst) > 0) 1364 logit("%s", inst); 1365 free(name); 1366 free(inst); 1367 free(lang); 1368 1369 num_prompts = packet_get_int(); 1370 /* 1371 * Begin to build info response packet based on prompts requested. 1372 * We commit to providing the correct number of responses, so if 1373 * further on we run into a problem that prevents this, we have to 1374 * be sure and clean this up and send a correct error response. 1375 */ 1376 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1377 packet_put_int(num_prompts); 1378 1379 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1380 for (i = 0; i < num_prompts; i++) { 1381 prompt = packet_get_string(NULL); 1382 echo = packet_get_char(); 1383 1384 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1385 1386 packet_put_cstring(response); 1387 explicit_bzero(response, strlen(response)); 1388 free(response); 1389 free(prompt); 1390 } 1391 packet_check_eom(); /* done with parsing incoming message. */ 1392 1393 packet_add_padding(64); 1394 packet_send(); 1395 } 1396 1397 static int 1398 ssh_keysign(Key *key, u_char **sigp, u_int *lenp, 1399 u_char *data, u_int datalen) 1400 { 1401 Buffer b; 1402 struct stat st; 1403 pid_t pid; 1404 int to[2], from[2], status, version = 2; 1405 1406 debug2("ssh_keysign called"); 1407 1408 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1409 error("ssh_keysign: not installed: %s", strerror(errno)); 1410 return -1; 1411 } 1412 if (fflush(stdout) != 0) 1413 error("ssh_keysign: fflush: %s", strerror(errno)); 1414 if (pipe(to) < 0) { 1415 error("ssh_keysign: pipe: %s", strerror(errno)); 1416 return -1; 1417 } 1418 if (pipe(from) < 0) { 1419 error("ssh_keysign: pipe: %s", strerror(errno)); 1420 return -1; 1421 } 1422 if ((pid = fork()) < 0) { 1423 error("ssh_keysign: fork: %s", strerror(errno)); 1424 return -1; 1425 } 1426 if (pid == 0) { 1427 /* keep the socket on exec */ 1428 fcntl(packet_get_connection_in(), F_SETFD, 0); 1429 permanently_drop_suid(getuid()); 1430 close(from[0]); 1431 if (dup2(from[1], STDOUT_FILENO) < 0) 1432 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1433 close(to[1]); 1434 if (dup2(to[0], STDIN_FILENO) < 0) 1435 fatal("ssh_keysign: dup2: %s", strerror(errno)); 1436 close(from[1]); 1437 close(to[0]); 1438 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); 1439 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, 1440 strerror(errno)); 1441 } 1442 close(from[1]); 1443 close(to[0]); 1444 1445 buffer_init(&b); 1446 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ 1447 buffer_put_string(&b, data, datalen); 1448 if (ssh_msg_send(to[1], version, &b) == -1) 1449 fatal("ssh_keysign: couldn't send request"); 1450 1451 if (ssh_msg_recv(from[0], &b) < 0) { 1452 error("ssh_keysign: no reply"); 1453 buffer_free(&b); 1454 return -1; 1455 } 1456 close(from[0]); 1457 close(to[1]); 1458 1459 while (waitpid(pid, &status, 0) < 0) 1460 if (errno != EINTR) 1461 break; 1462 1463 if (buffer_get_char(&b) != version) { 1464 error("ssh_keysign: bad version"); 1465 buffer_free(&b); 1466 return -1; 1467 } 1468 *sigp = buffer_get_string(&b, lenp); 1469 buffer_free(&b); 1470 1471 return 0; 1472 } 1473 1474 int 1475 userauth_hostbased(Authctxt *authctxt) 1476 { 1477 Key *private = NULL; 1478 Sensitive *sensitive = authctxt->sensitive; 1479 Buffer b; 1480 u_char *signature, *blob; 1481 char *chost, *pkalg, *p; 1482 const char *service; 1483 u_int blen, slen; 1484 int ok, i, found = 0; 1485 1486 /* check for a useful key */ 1487 for (i = 0; i < sensitive->nkeys; i++) { 1488 private = sensitive->keys[i]; 1489 if (private && private->type != KEY_RSA1) { 1490 found = 1; 1491 /* we take and free the key */ 1492 sensitive->keys[i] = NULL; 1493 break; 1494 } 1495 } 1496 if (!found) { 1497 debug("No more client hostkeys for hostbased authentication."); 1498 return 0; 1499 } 1500 if (key_to_blob(private, &blob, &blen) == 0) { 1501 key_free(private); 1502 return 0; 1503 } 1504 /* figure out a name for the client host */ 1505 p = get_local_name(packet_get_connection_in()); 1506 if (p == NULL) { 1507 error("userauth_hostbased: cannot get local ipaddr/name"); 1508 key_free(private); 1509 free(blob); 1510 return 0; 1511 } 1512 xasprintf(&chost, "%s.", p); 1513 debug2("userauth_hostbased: chost %s", chost); 1514 free(p); 1515 1516 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : 1517 authctxt->service; 1518 pkalg = xstrdup(key_ssh_name(private)); 1519 buffer_init(&b); 1520 /* construct data */ 1521 buffer_put_string(&b, session_id2, session_id2_len); 1522 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1523 buffer_put_cstring(&b, authctxt->server_user); 1524 buffer_put_cstring(&b, service); 1525 buffer_put_cstring(&b, authctxt->method->name); 1526 buffer_put_cstring(&b, pkalg); 1527 buffer_put_string(&b, blob, blen); 1528 buffer_put_cstring(&b, chost); 1529 buffer_put_cstring(&b, authctxt->local_user); 1530 #ifdef DEBUG_PK 1531 buffer_dump(&b); 1532 #endif 1533 if (sensitive->external_keysign) 1534 ok = ssh_keysign(private, &signature, &slen, 1535 buffer_ptr(&b), buffer_len(&b)); 1536 else 1537 ok = key_sign(private, &signature, &slen, 1538 buffer_ptr(&b), buffer_len(&b)); 1539 key_free(private); 1540 buffer_free(&b); 1541 if (ok != 0) { 1542 error("key_sign failed"); 1543 free(chost); 1544 free(pkalg); 1545 free(blob); 1546 return 0; 1547 } 1548 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1549 packet_put_cstring(authctxt->server_user); 1550 packet_put_cstring(authctxt->service); 1551 packet_put_cstring(authctxt->method->name); 1552 packet_put_cstring(pkalg); 1553 packet_put_string(blob, blen); 1554 packet_put_cstring(chost); 1555 packet_put_cstring(authctxt->local_user); 1556 packet_put_string(signature, slen); 1557 explicit_bzero(signature, slen); 1558 free(signature); 1559 free(chost); 1560 free(pkalg); 1561 free(blob); 1562 1563 packet_send(); 1564 return 1; 1565 } 1566 1567 /* find auth method */ 1568 1569 /* 1570 * given auth method name, if configurable options permit this method fill 1571 * in auth_ident field and return true, otherwise return false. 1572 */ 1573 static int 1574 authmethod_is_enabled(Authmethod *method) 1575 { 1576 if (method == NULL) 1577 return 0; 1578 /* return false if options indicate this method is disabled */ 1579 if (method->enabled == NULL || *method->enabled == 0) 1580 return 0; 1581 /* return false if batch mode is enabled but method needs interactive mode */ 1582 if (method->batch_flag != NULL && *method->batch_flag != 0) 1583 return 0; 1584 return 1; 1585 } 1586 1587 static Authmethod * 1588 authmethod_lookup(const char *name) 1589 { 1590 Authmethod *method = NULL; 1591 if (name != NULL) 1592 for (method = authmethods; method->name != NULL; method++) 1593 if (strcmp(name, method->name) == 0) 1594 return method; 1595 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1596 return NULL; 1597 } 1598 1599 /* XXX internal state */ 1600 static Authmethod *current = NULL; 1601 static char *supported = NULL; 1602 static char *preferred = NULL; 1603 1604 /* 1605 * Given the authentication method list sent by the server, return the 1606 * next method we should try. If the server initially sends a nil list, 1607 * use a built-in default list. 1608 */ 1609 static Authmethod * 1610 authmethod_get(char *authlist) 1611 { 1612 char *name = NULL; 1613 u_int next; 1614 1615 /* Use a suitable default if we're passed a nil list. */ 1616 if (authlist == NULL || strlen(authlist) == 0) 1617 authlist = options.preferred_authentications; 1618 1619 if (supported == NULL || strcmp(authlist, supported) != 0) { 1620 debug3("start over, passed a different list %s", authlist); 1621 free(supported); 1622 supported = xstrdup(authlist); 1623 preferred = options.preferred_authentications; 1624 debug3("preferred %s", preferred); 1625 current = NULL; 1626 } else if (current != NULL && authmethod_is_enabled(current)) 1627 return current; 1628 1629 for (;;) { 1630 if ((name = match_list(preferred, supported, &next)) == NULL) { 1631 debug("No more authentication methods to try."); 1632 current = NULL; 1633 return NULL; 1634 } 1635 preferred += next; 1636 debug3("authmethod_lookup %s", name); 1637 debug3("remaining preferred: %s", preferred); 1638 if ((current = authmethod_lookup(name)) != NULL && 1639 authmethod_is_enabled(current)) { 1640 debug3("authmethod_is_enabled %s", name); 1641 debug("Next authentication method: %s", name); 1642 free(name); 1643 return current; 1644 } 1645 free(name); 1646 } 1647 } 1648 1649 static char * 1650 authmethods_get(void) 1651 { 1652 Authmethod *method = NULL; 1653 Buffer b; 1654 char *list; 1655 1656 buffer_init(&b); 1657 for (method = authmethods; method->name != NULL; method++) { 1658 if (authmethod_is_enabled(method)) { 1659 if (buffer_len(&b) > 0) 1660 buffer_append(&b, ",", 1); 1661 buffer_append(&b, method->name, strlen(method->name)); 1662 } 1663 } 1664 buffer_append(&b, "\0", 1); 1665 list = xstrdup(buffer_ptr(&b)); 1666 buffer_free(&b); 1667 return list; 1668 } 1669 1670