1 /* $OpenBSD: sshconnect2.c,v 1.269 2018/03/03 03:01:50 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "buffer.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "key.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "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 #include "ssherr.h" 68 #include "utf8.h" 69 70 #ifdef GSSAPI 71 #include "ssh-gss.h" 72 #endif 73 74 /* import */ 75 extern char *client_version_string; 76 extern char *server_version_string; 77 extern Options options; 78 79 /* 80 * SSH2 key exchange 81 */ 82 83 u_char *session_id2 = NULL; 84 u_int session_id2_len = 0; 85 86 char *xxx_host; 87 struct sockaddr *xxx_hostaddr; 88 89 static int 90 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 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 = sshkey_type_from_name(alg)) == KEY_UNSPEC) 129 fatal("%s: unknown alg %s", __func__, alg); 130 if (lookup_key_in_hostkeys_by_type(hostkeys, 131 sshkey_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, 138 (*first == '\0' || *last == '\0') ? "" : ",", last); 139 if (*first != '\0') 140 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 141 142 free(first); 143 free(last); 144 free(hostname); 145 free(oavail); 146 free_hostkeys(hostkeys); 147 148 return ret; 149 } 150 151 void 152 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 153 { 154 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 155 char *s; 156 struct kex *kex; 157 int r; 158 159 xxx_host = host; 160 xxx_hostaddr = hostaddr; 161 162 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 163 fatal("%s: kex_names_cat", __func__); 164 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 165 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 166 compat_cipher_proposal(options.ciphers); 167 myproposal[PROPOSAL_ENC_ALGS_STOC] = 168 compat_cipher_proposal(options.ciphers); 169 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 170 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 171 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 172 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 173 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 174 if (options.hostkeyalgorithms != NULL) { 175 if (kex_assemble_names(KEX_DEFAULT_PK_ALG, 176 &options.hostkeyalgorithms) != 0) 177 fatal("%s: kex_assemble_namelist", __func__); 178 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 179 compat_pkalg_proposal(options.hostkeyalgorithms); 180 } else { 181 /* Enforce default */ 182 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 183 /* Prefer algorithms that we already have keys for */ 184 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 185 compat_pkalg_proposal( 186 order_hostkeyalgs(host, hostaddr, port)); 187 } 188 189 if (options.rekey_limit || options.rekey_interval) 190 packet_set_rekey_limits(options.rekey_limit, 191 options.rekey_interval); 192 193 /* start key exchange */ 194 if ((r = kex_setup(active_state, myproposal)) != 0) 195 fatal("kex_setup: %s", ssh_err(r)); 196 kex = active_state->kex; 197 #ifdef WITH_OPENSSL 198 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 199 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 200 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 201 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 202 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 203 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 204 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 205 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 206 #endif 207 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 208 kex->client_version_string=client_version_string; 209 kex->server_version_string=server_version_string; 210 kex->verify_host_key=&verify_host_key_callback; 211 212 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 213 214 /* remove ext-info from the KEX proposals for rekeying */ 215 myproposal[PROPOSAL_KEX_ALGS] = 216 compat_kex_proposal(options.kex_algorithms); 217 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 218 fatal("kex_prop2buf: %s", ssh_err(r)); 219 220 session_id2 = kex->session_id; 221 session_id2_len = kex->session_id_len; 222 223 #ifdef DEBUG_KEXDH 224 /* send 1st encrypted/maced/compressed message */ 225 packet_start(SSH2_MSG_IGNORE); 226 packet_put_cstring("markus"); 227 packet_send(); 228 packet_write_wait(); 229 #endif 230 } 231 232 /* 233 * Authenticate user 234 */ 235 236 typedef struct cauthctxt Authctxt; 237 typedef struct cauthmethod Authmethod; 238 typedef struct identity Identity; 239 typedef struct idlist Idlist; 240 241 struct identity { 242 TAILQ_ENTRY(identity) next; 243 int agent_fd; /* >=0 if agent supports key */ 244 struct sshkey *key; /* public/private key */ 245 char *filename; /* comment for agent-only keys */ 246 int tried; 247 int isprivate; /* key points to the private key */ 248 int userprovided; 249 }; 250 TAILQ_HEAD(idlist, identity); 251 252 struct cauthctxt { 253 const char *server_user; 254 const char *local_user; 255 const char *host; 256 const char *service; 257 struct cauthmethod *method; 258 sig_atomic_t success; 259 char *authlist; 260 int attempt; 261 /* pubkey */ 262 struct idlist keys; 263 int agent_fd; 264 /* hostbased */ 265 Sensitive *sensitive; 266 char *oktypes, *ktypes; 267 const char *active_ktype; 268 /* kbd-interactive */ 269 int info_req_seen; 270 /* generic */ 271 void *methoddata; 272 }; 273 274 struct cauthmethod { 275 char *name; /* string to compare against server's list */ 276 int (*userauth)(Authctxt *authctxt); 277 void (*cleanup)(Authctxt *authctxt); 278 int *enabled; /* flag in option struct that enables method */ 279 int *batch_flag; /* flag in option struct that disables method */ 280 }; 281 282 int input_userauth_service_accept(int, u_int32_t, struct ssh *); 283 int input_userauth_ext_info(int, u_int32_t, struct ssh *); 284 int input_userauth_success(int, u_int32_t, struct ssh *); 285 int input_userauth_success_unexpected(int, u_int32_t, struct ssh *); 286 int input_userauth_failure(int, u_int32_t, struct ssh *); 287 int input_userauth_banner(int, u_int32_t, struct ssh *); 288 int input_userauth_error(int, u_int32_t, struct ssh *); 289 int input_userauth_info_req(int, u_int32_t, struct ssh *); 290 int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 291 int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 292 293 int userauth_none(Authctxt *); 294 int userauth_pubkey(Authctxt *); 295 int userauth_passwd(Authctxt *); 296 int userauth_kbdint(Authctxt *); 297 int userauth_hostbased(Authctxt *); 298 299 #ifdef GSSAPI 300 int userauth_gssapi(Authctxt *authctxt); 301 int input_gssapi_response(int type, u_int32_t, struct ssh *); 302 int input_gssapi_token(int type, u_int32_t, struct ssh *); 303 int input_gssapi_hash(int type, u_int32_t, struct ssh *); 304 int input_gssapi_error(int, u_int32_t, struct ssh *); 305 int input_gssapi_errtok(int, u_int32_t, struct ssh *); 306 #endif 307 308 void userauth(Authctxt *, char *); 309 310 static int sign_and_send_pubkey(Authctxt *, Identity *); 311 static void pubkey_prepare(Authctxt *); 312 static void pubkey_cleanup(Authctxt *); 313 static void pubkey_reset(Authctxt *); 314 static struct sshkey *load_identity_file(Identity *); 315 316 static Authmethod *authmethod_get(char *authlist); 317 static Authmethod *authmethod_lookup(const char *name); 318 static char *authmethods_get(void); 319 320 Authmethod authmethods[] = { 321 #ifdef GSSAPI 322 {"gssapi-with-mic", 323 userauth_gssapi, 324 NULL, 325 &options.gss_authentication, 326 NULL}, 327 #endif 328 {"hostbased", 329 userauth_hostbased, 330 NULL, 331 &options.hostbased_authentication, 332 NULL}, 333 {"publickey", 334 userauth_pubkey, 335 NULL, 336 &options.pubkey_authentication, 337 NULL}, 338 {"keyboard-interactive", 339 userauth_kbdint, 340 NULL, 341 &options.kbd_interactive_authentication, 342 &options.batch_mode}, 343 {"password", 344 userauth_passwd, 345 NULL, 346 &options.password_authentication, 347 &options.batch_mode}, 348 {"none", 349 userauth_none, 350 NULL, 351 NULL, 352 NULL}, 353 {NULL, NULL, NULL, NULL, NULL} 354 }; 355 356 void 357 ssh_userauth2(const char *local_user, const char *server_user, char *host, 358 Sensitive *sensitive) 359 { 360 struct ssh *ssh = active_state; 361 Authctxt authctxt; 362 int r; 363 364 if (options.challenge_response_authentication) 365 options.kbd_interactive_authentication = 1; 366 if (options.preferred_authentications == NULL) 367 options.preferred_authentications = authmethods_get(); 368 369 /* setup authentication context */ 370 memset(&authctxt, 0, sizeof(authctxt)); 371 pubkey_prepare(&authctxt); 372 authctxt.server_user = server_user; 373 authctxt.local_user = local_user; 374 authctxt.host = host; 375 authctxt.service = "ssh-connection"; /* service name */ 376 authctxt.success = 0; 377 authctxt.method = authmethod_lookup("none"); 378 authctxt.authlist = NULL; 379 authctxt.methoddata = NULL; 380 authctxt.sensitive = sensitive; 381 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 382 authctxt.info_req_seen = 0; 383 authctxt.agent_fd = -1; 384 if (authctxt.method == NULL) 385 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 386 387 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 388 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 389 (r = sshpkt_send(ssh)) != 0) 390 fatal("%s: %s", __func__, ssh_err(r)); 391 392 ssh->authctxt = &authctxt; 393 ssh_dispatch_init(ssh, &input_userauth_error); 394 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 395 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 396 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 397 ssh->authctxt = NULL; 398 399 pubkey_cleanup(&authctxt); 400 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 401 402 if (!authctxt.success) 403 fatal("Authentication failed."); 404 debug("Authentication succeeded (%s).", authctxt.method->name); 405 } 406 407 /* ARGSUSED */ 408 int 409 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 410 { 411 Authctxt *authctxt = ssh->authctxt; 412 int r; 413 414 if (ssh_packet_remaining(ssh) > 0) { 415 char *reply; 416 417 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 418 goto out; 419 debug2("service_accept: %s", reply); 420 free(reply); 421 } else { 422 debug2("buggy server: service_accept w/o service"); 423 } 424 if ((r = sshpkt_get_end(ssh)) != 0) 425 goto out; 426 debug("SSH2_MSG_SERVICE_ACCEPT received"); 427 428 /* initial userauth request */ 429 userauth_none(authctxt); 430 431 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 432 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 433 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 434 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 435 r = 0; 436 out: 437 return r; 438 } 439 440 /* ARGSUSED */ 441 int 442 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 443 { 444 return kex_input_ext_info(type, seqnr, ssh); 445 } 446 447 void 448 userauth(Authctxt *authctxt, char *authlist) 449 { 450 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 451 authctxt->method->cleanup(authctxt); 452 453 free(authctxt->methoddata); 454 authctxt->methoddata = NULL; 455 if (authlist == NULL) { 456 authlist = authctxt->authlist; 457 } else { 458 free(authctxt->authlist); 459 authctxt->authlist = authlist; 460 } 461 for (;;) { 462 Authmethod *method = authmethod_get(authlist); 463 if (method == NULL) 464 fatal("%s@%s: Permission denied (%s).", 465 authctxt->server_user, authctxt->host, authlist); 466 authctxt->method = method; 467 468 /* reset the per method handler */ 469 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, 470 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 471 472 /* and try new method */ 473 if (method->userauth(authctxt) != 0) { 474 debug2("we sent a %s packet, wait for reply", method->name); 475 break; 476 } else { 477 debug2("we did not send a packet, disable method"); 478 method->enabled = NULL; 479 } 480 } 481 } 482 483 /* ARGSUSED */ 484 int 485 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 486 { 487 fatal("input_userauth_error: bad message during authentication: " 488 "type %d", type); 489 return 0; 490 } 491 492 /* ARGSUSED */ 493 int 494 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 495 { 496 char *msg, *lang; 497 u_int len; 498 499 debug3("%s", __func__); 500 msg = packet_get_string(&len); 501 lang = packet_get_string(NULL); 502 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 503 fmprintf(stderr, "%s", msg); 504 free(msg); 505 free(lang); 506 return 0; 507 } 508 509 /* ARGSUSED */ 510 int 511 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 512 { 513 Authctxt *authctxt = ssh->authctxt; 514 515 if (authctxt == NULL) 516 fatal("input_userauth_success: no authentication context"); 517 free(authctxt->authlist); 518 authctxt->authlist = NULL; 519 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 520 authctxt->method->cleanup(authctxt); 521 free(authctxt->methoddata); 522 authctxt->methoddata = NULL; 523 authctxt->success = 1; /* break out */ 524 return 0; 525 } 526 527 int 528 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 529 { 530 Authctxt *authctxt = ssh->authctxt; 531 532 if (authctxt == NULL) 533 fatal("%s: no authentication context", __func__); 534 535 fatal("Unexpected authentication success during %s.", 536 authctxt->method->name); 537 return 0; 538 } 539 540 /* ARGSUSED */ 541 int 542 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 543 { 544 Authctxt *authctxt = ssh->authctxt; 545 char *authlist = NULL; 546 int partial; 547 548 if (authctxt == NULL) 549 fatal("input_userauth_failure: no authentication context"); 550 551 authlist = packet_get_string(NULL); 552 partial = packet_get_char(); 553 packet_check_eom(); 554 555 if (partial != 0) { 556 verbose("Authenticated with partial success."); 557 /* reset state */ 558 pubkey_reset(authctxt); 559 } 560 debug("Authentications that can continue: %s", authlist); 561 562 userauth(authctxt, authlist); 563 return 0; 564 } 565 566 /* ARGSUSED */ 567 int 568 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 569 { 570 Authctxt *authctxt = ssh->authctxt; 571 struct sshkey *key = NULL; 572 Identity *id = NULL; 573 int pktype, sent = 0; 574 u_int alen, blen; 575 char *pkalg, *fp; 576 u_char *pkblob; 577 578 if (authctxt == NULL) 579 fatal("input_userauth_pk_ok: no authentication context"); 580 581 pkalg = packet_get_string(&alen); 582 pkblob = packet_get_string(&blen); 583 packet_check_eom(); 584 585 debug("Server accepts key: pkalg %s blen %u", pkalg, blen); 586 587 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { 588 debug("unknown pkalg %s", pkalg); 589 goto done; 590 } 591 if ((key = key_from_blob(pkblob, blen)) == NULL) { 592 debug("no key from blob. pkalg %s", pkalg); 593 goto done; 594 } 595 if (key->type != pktype) { 596 error("input_userauth_pk_ok: type mismatch " 597 "for decoded key (received %d, expected %d)", 598 key->type, pktype); 599 goto done; 600 } 601 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 602 SSH_FP_DEFAULT)) == NULL) 603 goto done; 604 debug2("input_userauth_pk_ok: fp %s", fp); 605 free(fp); 606 607 /* 608 * search keys in the reverse order, because last candidate has been 609 * moved to the end of the queue. this also avoids confusion by 610 * duplicate keys 611 */ 612 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 613 if (key_equal(key, id->key)) { 614 sent = sign_and_send_pubkey(authctxt, id); 615 break; 616 } 617 } 618 done: 619 key_free(key); 620 free(pkalg); 621 free(pkblob); 622 623 /* try another method if we did not send a packet */ 624 if (sent == 0) 625 userauth(authctxt, NULL); 626 return 0; 627 } 628 629 #ifdef GSSAPI 630 int 631 userauth_gssapi(Authctxt *authctxt) 632 { 633 Gssctxt *gssctxt = NULL; 634 static gss_OID_set gss_supported = NULL; 635 static u_int mech = 0; 636 OM_uint32 min; 637 int ok = 0; 638 639 /* Try one GSSAPI method at a time, rather than sending them all at 640 * once. */ 641 642 if (gss_supported == NULL) 643 gss_indicate_mechs(&min, &gss_supported); 644 645 /* Check to see if the mechanism is usable before we offer it */ 646 while (mech < gss_supported->count && !ok) { 647 /* My DER encoding requires length<128 */ 648 if (gss_supported->elements[mech].length < 128 && 649 ssh_gssapi_check_mechanism(&gssctxt, 650 &gss_supported->elements[mech], authctxt->host)) { 651 ok = 1; /* Mechanism works */ 652 } else { 653 mech++; 654 } 655 } 656 657 if (!ok) 658 return 0; 659 660 authctxt->methoddata=(void *)gssctxt; 661 662 packet_start(SSH2_MSG_USERAUTH_REQUEST); 663 packet_put_cstring(authctxt->server_user); 664 packet_put_cstring(authctxt->service); 665 packet_put_cstring(authctxt->method->name); 666 667 packet_put_int(1); 668 669 packet_put_int((gss_supported->elements[mech].length) + 2); 670 packet_put_char(SSH_GSS_OIDTYPE); 671 packet_put_char(gss_supported->elements[mech].length); 672 packet_put_raw(gss_supported->elements[mech].elements, 673 gss_supported->elements[mech].length); 674 675 packet_send(); 676 677 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 678 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 679 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 680 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 681 682 mech++; /* Move along to next candidate */ 683 684 return 1; 685 } 686 687 static OM_uint32 688 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 689 { 690 Authctxt *authctxt = ssh->authctxt; 691 Gssctxt *gssctxt = authctxt->methoddata; 692 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 693 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 694 gss_buffer_desc gssbuf; 695 OM_uint32 status, ms, flags; 696 Buffer b; 697 698 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 699 recv_tok, &send_tok, &flags); 700 701 if (send_tok.length > 0) { 702 if (GSS_ERROR(status)) 703 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 704 else 705 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 706 707 packet_put_string(send_tok.value, send_tok.length); 708 packet_send(); 709 gss_release_buffer(&ms, &send_tok); 710 } 711 712 if (status == GSS_S_COMPLETE) { 713 /* send either complete or MIC, depending on mechanism */ 714 if (!(flags & GSS_C_INTEG_FLAG)) { 715 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); 716 packet_send(); 717 } else { 718 ssh_gssapi_buildmic(&b, authctxt->server_user, 719 authctxt->service, "gssapi-with-mic"); 720 721 gssbuf.value = buffer_ptr(&b); 722 gssbuf.length = buffer_len(&b); 723 724 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 725 726 if (!GSS_ERROR(status)) { 727 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); 728 packet_put_string(mic.value, mic.length); 729 730 packet_send(); 731 } 732 733 buffer_free(&b); 734 gss_release_buffer(&ms, &mic); 735 } 736 } 737 738 return status; 739 } 740 741 /* ARGSUSED */ 742 int 743 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 744 { 745 Authctxt *authctxt = ssh->authctxt; 746 Gssctxt *gssctxt; 747 int oidlen; 748 char *oidv; 749 750 if (authctxt == NULL) 751 fatal("input_gssapi_response: no authentication context"); 752 gssctxt = authctxt->methoddata; 753 754 /* Setup our OID */ 755 oidv = packet_get_string(&oidlen); 756 757 if (oidlen <= 2 || 758 oidv[0] != SSH_GSS_OIDTYPE || 759 oidv[1] != oidlen - 2) { 760 free(oidv); 761 debug("Badly encoded mechanism OID received"); 762 userauth(authctxt, NULL); 763 return 0; 764 } 765 766 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 767 fatal("Server returned different OID than expected"); 768 769 packet_check_eom(); 770 771 free(oidv); 772 773 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 774 /* Start again with next method on list */ 775 debug("Trying to start again"); 776 userauth(authctxt, NULL); 777 return 0; 778 } 779 return 0; 780 } 781 782 /* ARGSUSED */ 783 int 784 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 785 { 786 Authctxt *authctxt = ssh->authctxt; 787 gss_buffer_desc recv_tok; 788 OM_uint32 status; 789 u_int slen; 790 791 if (authctxt == NULL) 792 fatal("input_gssapi_response: no authentication context"); 793 794 recv_tok.value = packet_get_string(&slen); 795 recv_tok.length = slen; /* safe typecast */ 796 797 packet_check_eom(); 798 799 status = process_gssapi_token(ssh, &recv_tok); 800 801 free(recv_tok.value); 802 803 if (GSS_ERROR(status)) { 804 /* Start again with the next method in the list */ 805 userauth(authctxt, NULL); 806 return 0; 807 } 808 return 0; 809 } 810 811 /* ARGSUSED */ 812 int 813 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 814 { 815 Authctxt *authctxt = ssh->authctxt; 816 Gssctxt *gssctxt; 817 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 818 gss_buffer_desc recv_tok; 819 OM_uint32 ms; 820 u_int len; 821 822 if (authctxt == NULL) 823 fatal("input_gssapi_response: no authentication context"); 824 gssctxt = authctxt->methoddata; 825 826 recv_tok.value = packet_get_string(&len); 827 recv_tok.length = len; 828 829 packet_check_eom(); 830 831 /* Stick it into GSSAPI and see what it says */ 832 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 833 &recv_tok, &send_tok, NULL); 834 835 free(recv_tok.value); 836 gss_release_buffer(&ms, &send_tok); 837 838 /* Server will be returning a failed packet after this one */ 839 return 0; 840 } 841 842 /* ARGSUSED */ 843 int 844 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 845 { 846 char *msg; 847 char *lang; 848 849 /* maj */(void)packet_get_int(); 850 /* min */(void)packet_get_int(); 851 msg=packet_get_string(NULL); 852 lang=packet_get_string(NULL); 853 854 packet_check_eom(); 855 856 debug("Server GSSAPI Error:\n%s", msg); 857 free(msg); 858 free(lang); 859 return 0; 860 } 861 #endif /* GSSAPI */ 862 863 int 864 userauth_none(Authctxt *authctxt) 865 { 866 /* initial userauth request */ 867 packet_start(SSH2_MSG_USERAUTH_REQUEST); 868 packet_put_cstring(authctxt->server_user); 869 packet_put_cstring(authctxt->service); 870 packet_put_cstring(authctxt->method->name); 871 packet_send(); 872 return 1; 873 } 874 875 int 876 userauth_passwd(Authctxt *authctxt) 877 { 878 static int attempt = 0; 879 char prompt[256]; 880 char *password; 881 const char *host = options.host_key_alias ? options.host_key_alias : 882 authctxt->host; 883 884 if (attempt++ >= options.number_of_password_prompts) 885 return 0; 886 887 if (attempt != 1) 888 error("Permission denied, please try again."); 889 890 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 891 authctxt->server_user, host); 892 password = read_passphrase(prompt, 0); 893 packet_start(SSH2_MSG_USERAUTH_REQUEST); 894 packet_put_cstring(authctxt->server_user); 895 packet_put_cstring(authctxt->service); 896 packet_put_cstring(authctxt->method->name); 897 packet_put_char(0); 898 packet_put_cstring(password); 899 explicit_bzero(password, strlen(password)); 900 free(password); 901 packet_add_padding(64); 902 packet_send(); 903 904 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 905 &input_userauth_passwd_changereq); 906 907 return 1; 908 } 909 910 /* 911 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 912 */ 913 /* ARGSUSED */ 914 int 915 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 916 { 917 Authctxt *authctxt = ssh->authctxt; 918 char *info, *lang, *password = NULL, *retype = NULL; 919 char prompt[256]; 920 const char *host; 921 922 debug2("input_userauth_passwd_changereq"); 923 924 if (authctxt == NULL) 925 fatal("input_userauth_passwd_changereq: " 926 "no authentication context"); 927 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 928 929 info = packet_get_string(NULL); 930 lang = packet_get_string(NULL); 931 if (strlen(info) > 0) 932 logit("%s", info); 933 free(info); 934 free(lang); 935 packet_start(SSH2_MSG_USERAUTH_REQUEST); 936 packet_put_cstring(authctxt->server_user); 937 packet_put_cstring(authctxt->service); 938 packet_put_cstring(authctxt->method->name); 939 packet_put_char(1); /* additional info */ 940 snprintf(prompt, sizeof(prompt), 941 "Enter %.30s@%.128s's old password: ", 942 authctxt->server_user, host); 943 password = read_passphrase(prompt, 0); 944 packet_put_cstring(password); 945 explicit_bzero(password, strlen(password)); 946 free(password); 947 password = NULL; 948 while (password == NULL) { 949 snprintf(prompt, sizeof(prompt), 950 "Enter %.30s@%.128s's new password: ", 951 authctxt->server_user, host); 952 password = read_passphrase(prompt, RP_ALLOW_EOF); 953 if (password == NULL) { 954 /* bail out */ 955 return 0; 956 } 957 snprintf(prompt, sizeof(prompt), 958 "Retype %.30s@%.128s's new password: ", 959 authctxt->server_user, host); 960 retype = read_passphrase(prompt, 0); 961 if (strcmp(password, retype) != 0) { 962 explicit_bzero(password, strlen(password)); 963 free(password); 964 logit("Mismatch; try again, EOF to quit."); 965 password = NULL; 966 } 967 explicit_bzero(retype, strlen(retype)); 968 free(retype); 969 } 970 packet_put_cstring(password); 971 explicit_bzero(password, strlen(password)); 972 free(password); 973 packet_add_padding(64); 974 packet_send(); 975 976 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 977 &input_userauth_passwd_changereq); 978 return 0; 979 } 980 981 static const char * 982 key_sign_encode(const struct sshkey *key) 983 { 984 struct ssh *ssh = active_state; 985 986 if (key->type == KEY_RSA) { 987 switch (ssh->kex->rsa_sha2) { 988 case 256: 989 return "rsa-sha2-256"; 990 case 512: 991 return "rsa-sha2-512"; 992 } 993 } 994 return key_ssh_name(key); 995 } 996 997 /* 998 * Some agents will return ssh-rsa signatures when asked to make a 999 * rsa-sha2-* signature. Check what they actually gave back and warn the 1000 * user if the agent has returned an unexpected type. 1001 */ 1002 static int 1003 check_sigtype(const struct sshkey *key, const u_char *sig, size_t len) 1004 { 1005 int r; 1006 char *sigtype = NULL; 1007 const char *alg = key_sign_encode(key); 1008 1009 if ((r = sshkey_sigtype(sig, len, &sigtype)) != 0) 1010 return r; 1011 if (strcmp(sigtype, alg) != 0) { 1012 logit("warning: agent returned different signature type %s " 1013 "(expected %s)", sigtype, alg); 1014 } 1015 free(sigtype); 1016 /* Incorrect signature types aren't an error ... yet */ 1017 return 0; 1018 } 1019 1020 static int 1021 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1022 const u_char *data, size_t datalen, u_int compat) 1023 { 1024 struct sshkey *prv; 1025 int r; 1026 1027 /* the agent supports this key */ 1028 if (id->key != NULL && id->agent_fd != -1) { 1029 if ((r = ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1030 data, datalen, key_sign_encode(id->key), compat)) != 0 || 1031 (r = check_sigtype(id->key, *sigp, *lenp)) != 0) 1032 return r; 1033 return 0; 1034 } 1035 1036 /* 1037 * we have already loaded the private key or 1038 * the private key is stored in external hardware 1039 */ 1040 if (id->key != NULL && 1041 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) 1042 return (sshkey_sign(id->key, sigp, lenp, data, datalen, 1043 key_sign_encode(id->key), compat)); 1044 1045 /* load the private key from the file */ 1046 if ((prv = load_identity_file(id)) == NULL) 1047 return SSH_ERR_KEY_NOT_FOUND; 1048 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1049 error("%s: private key %s contents do not match public", 1050 __func__, id->filename); 1051 return SSH_ERR_KEY_NOT_FOUND; 1052 } 1053 r = sshkey_sign(prv, sigp, lenp, data, datalen, 1054 key_sign_encode(prv), compat); 1055 sshkey_free(prv); 1056 return r; 1057 } 1058 1059 static int 1060 id_filename_matches(Identity *id, Identity *private_id) 1061 { 1062 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1063 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1064 size_t i, slen; 1065 1066 if (strcmp(id->filename, private_id->filename) == 0) 1067 return 1; 1068 for (i = 0; suffixes[i]; i++) { 1069 slen = strlen(suffixes[i]); 1070 if (len > slen && plen == len - slen && 1071 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1072 memcmp(id->filename, private_id->filename, plen) == 0) 1073 return 1; 1074 } 1075 return 0; 1076 } 1077 1078 static int 1079 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1080 { 1081 Buffer b; 1082 Identity *private_id; 1083 u_char *blob, *signature; 1084 size_t slen; 1085 u_int bloblen, skip = 0; 1086 int matched, ret = -1, have_sig = 1; 1087 char *fp; 1088 1089 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1090 SSH_FP_DEFAULT)) == NULL) 1091 return 0; 1092 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1093 free(fp); 1094 1095 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1096 /* we cannot handle this key */ 1097 debug3("sign_and_send_pubkey: cannot handle key"); 1098 return 0; 1099 } 1100 /* data to be signed */ 1101 buffer_init(&b); 1102 if (datafellows & SSH_OLD_SESSIONID) { 1103 buffer_append(&b, session_id2, session_id2_len); 1104 skip = session_id2_len; 1105 } else { 1106 buffer_put_string(&b, session_id2, session_id2_len); 1107 skip = buffer_len(&b); 1108 } 1109 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1110 buffer_put_cstring(&b, authctxt->server_user); 1111 buffer_put_cstring(&b, authctxt->service); 1112 buffer_put_cstring(&b, authctxt->method->name); 1113 buffer_put_char(&b, have_sig); 1114 buffer_put_cstring(&b, key_sign_encode(id->key)); 1115 buffer_put_string(&b, blob, bloblen); 1116 1117 /* 1118 * If the key is an certificate, try to find a matching private key 1119 * and use it to complete the signature. 1120 * If no such private key exists, fall back to trying the certificate 1121 * key itself in case it has a private half already loaded. 1122 */ 1123 if (key_is_cert(id->key)) { 1124 matched = 0; 1125 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1126 if (sshkey_equal_public(id->key, private_id->key) && 1127 id->key->type != private_id->key->type) { 1128 id = private_id; 1129 matched = 1; 1130 break; 1131 } 1132 } 1133 /* 1134 * Exact key matches are preferred, but also allow 1135 * filename matches for non-PKCS#11/agent keys that 1136 * didn't load public keys. This supports the case 1137 * of keeping just a private key file and public 1138 * certificate on disk. 1139 */ 1140 if (!matched && !id->isprivate && id->agent_fd == -1 && 1141 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1142 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1143 if (private_id->key == NULL && 1144 id_filename_matches(id, private_id)) { 1145 id = private_id; 1146 matched = 1; 1147 break; 1148 } 1149 } 1150 } 1151 if (matched) { 1152 debug2("%s: using private key \"%s\"%s for " 1153 "certificate", __func__, id->filename, 1154 id->agent_fd != -1 ? " from agent" : ""); 1155 } else { 1156 debug("%s: no separate private key for certificate " 1157 "\"%s\"", __func__, id->filename); 1158 } 1159 } 1160 1161 /* generate signature */ 1162 ret = identity_sign(id, &signature, &slen, 1163 buffer_ptr(&b), buffer_len(&b), datafellows); 1164 if (ret != 0) { 1165 if (ret != SSH_ERR_KEY_NOT_FOUND) 1166 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1167 free(blob); 1168 buffer_free(&b); 1169 return 0; 1170 } 1171 #ifdef DEBUG_PK 1172 buffer_dump(&b); 1173 #endif 1174 free(blob); 1175 1176 /* append signature */ 1177 buffer_put_string(&b, signature, slen); 1178 free(signature); 1179 1180 /* skip session id and packet type */ 1181 if (buffer_len(&b) < skip + 1) 1182 fatal("userauth_pubkey: internal error"); 1183 buffer_consume(&b, skip + 1); 1184 1185 /* put remaining data from buffer into packet */ 1186 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1187 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1188 buffer_free(&b); 1189 packet_send(); 1190 1191 return 1; 1192 } 1193 1194 static int 1195 send_pubkey_test(Authctxt *authctxt, Identity *id) 1196 { 1197 u_char *blob; 1198 u_int bloblen, have_sig = 0; 1199 1200 debug3("send_pubkey_test"); 1201 1202 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1203 /* we cannot handle this key */ 1204 debug3("send_pubkey_test: cannot handle key"); 1205 return 0; 1206 } 1207 /* register callback for USERAUTH_PK_OK message */ 1208 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1209 1210 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1211 packet_put_cstring(authctxt->server_user); 1212 packet_put_cstring(authctxt->service); 1213 packet_put_cstring(authctxt->method->name); 1214 packet_put_char(have_sig); 1215 packet_put_cstring(key_sign_encode(id->key)); 1216 packet_put_string(blob, bloblen); 1217 free(blob); 1218 packet_send(); 1219 return 1; 1220 } 1221 1222 static struct sshkey * 1223 load_identity_file(Identity *id) 1224 { 1225 struct sshkey *private = NULL; 1226 char prompt[300], *passphrase, *comment; 1227 int r, perm_ok = 0, quit = 0, i; 1228 struct stat st; 1229 1230 if (stat(id->filename, &st) < 0) { 1231 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1232 id->filename, strerror(errno)); 1233 return NULL; 1234 } 1235 snprintf(prompt, sizeof prompt, 1236 "Enter passphrase for key '%.100s': ", id->filename); 1237 for (i = 0; i <= options.number_of_password_prompts; i++) { 1238 if (i == 0) 1239 passphrase = ""; 1240 else { 1241 passphrase = read_passphrase(prompt, 0); 1242 if (*passphrase == '\0') { 1243 debug2("no passphrase given, try next key"); 1244 free(passphrase); 1245 break; 1246 } 1247 } 1248 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1249 passphrase, &private, &comment, &perm_ok))) { 1250 case 0: 1251 break; 1252 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1253 if (options.batch_mode) { 1254 quit = 1; 1255 break; 1256 } 1257 if (i != 0) 1258 debug2("bad passphrase given, try again..."); 1259 break; 1260 case SSH_ERR_SYSTEM_ERROR: 1261 if (errno == ENOENT) { 1262 debug2("Load key \"%s\": %s", 1263 id->filename, ssh_err(r)); 1264 quit = 1; 1265 break; 1266 } 1267 /* FALLTHROUGH */ 1268 default: 1269 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1270 quit = 1; 1271 break; 1272 } 1273 if (!quit && private != NULL && id->agent_fd == -1 && 1274 !(id->key && id->isprivate)) 1275 maybe_add_key_to_agent(id->filename, private, comment, 1276 passphrase); 1277 if (i > 0) { 1278 explicit_bzero(passphrase, strlen(passphrase)); 1279 free(passphrase); 1280 } 1281 free(comment); 1282 if (private != NULL || quit) 1283 break; 1284 } 1285 return private; 1286 } 1287 1288 /* 1289 * try keys in the following order: 1290 * 1. certificates listed in the config file 1291 * 2. other input certificates 1292 * 3. agent keys that are found in the config file 1293 * 4. other agent keys 1294 * 5. keys that are only listed in the config file 1295 */ 1296 static void 1297 pubkey_prepare(Authctxt *authctxt) 1298 { 1299 struct identity *id, *id2, *tmp; 1300 struct idlist agent, files, *preferred; 1301 struct sshkey *key; 1302 int agent_fd = -1, i, r, found; 1303 size_t j; 1304 struct ssh_identitylist *idlist; 1305 1306 TAILQ_INIT(&agent); /* keys from the agent */ 1307 TAILQ_INIT(&files); /* keys from the config file */ 1308 preferred = &authctxt->keys; 1309 TAILQ_INIT(preferred); /* preferred order of keys */ 1310 1311 /* list of keys stored in the filesystem and PKCS#11 */ 1312 for (i = 0; i < options.num_identity_files; i++) { 1313 key = options.identity_keys[i]; 1314 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1315 continue; 1316 options.identity_keys[i] = NULL; 1317 id = xcalloc(1, sizeof(*id)); 1318 id->agent_fd = -1; 1319 id->key = key; 1320 id->filename = xstrdup(options.identity_files[i]); 1321 id->userprovided = options.identity_file_userprovided[i]; 1322 TAILQ_INSERT_TAIL(&files, id, next); 1323 } 1324 /* list of certificates specified by user */ 1325 for (i = 0; i < options.num_certificate_files; i++) { 1326 key = options.certificates[i]; 1327 if (!key_is_cert(key) || key->cert == NULL || 1328 key->cert->type != SSH2_CERT_TYPE_USER) 1329 continue; 1330 id = xcalloc(1, sizeof(*id)); 1331 id->agent_fd = -1; 1332 id->key = key; 1333 id->filename = xstrdup(options.certificate_files[i]); 1334 id->userprovided = options.certificate_file_userprovided[i]; 1335 TAILQ_INSERT_TAIL(preferred, id, next); 1336 } 1337 /* list of keys supported by the agent */ 1338 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1339 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1340 debug("%s: ssh_get_authentication_socket: %s", 1341 __func__, ssh_err(r)); 1342 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1343 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1344 debug("%s: ssh_fetch_identitylist: %s", 1345 __func__, ssh_err(r)); 1346 close(agent_fd); 1347 } else { 1348 for (j = 0; j < idlist->nkeys; j++) { 1349 found = 0; 1350 TAILQ_FOREACH(id, &files, next) { 1351 /* 1352 * agent keys from the config file are 1353 * preferred 1354 */ 1355 if (sshkey_equal(idlist->keys[j], id->key)) { 1356 TAILQ_REMOVE(&files, id, next); 1357 TAILQ_INSERT_TAIL(preferred, id, next); 1358 id->agent_fd = agent_fd; 1359 found = 1; 1360 break; 1361 } 1362 } 1363 if (!found && !options.identities_only) { 1364 id = xcalloc(1, sizeof(*id)); 1365 /* XXX "steals" key/comment from idlist */ 1366 id->key = idlist->keys[j]; 1367 id->filename = idlist->comments[j]; 1368 idlist->keys[j] = NULL; 1369 idlist->comments[j] = NULL; 1370 id->agent_fd = agent_fd; 1371 TAILQ_INSERT_TAIL(&agent, id, next); 1372 } 1373 } 1374 ssh_free_identitylist(idlist); 1375 /* append remaining agent keys */ 1376 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1377 TAILQ_REMOVE(&agent, id, next); 1378 TAILQ_INSERT_TAIL(preferred, id, next); 1379 } 1380 authctxt->agent_fd = agent_fd; 1381 } 1382 /* Prefer PKCS11 keys that are explicitly listed */ 1383 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1384 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1385 continue; 1386 found = 0; 1387 TAILQ_FOREACH(id2, &files, next) { 1388 if (id2->key == NULL || 1389 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1390 continue; 1391 if (sshkey_equal(id->key, id2->key)) { 1392 TAILQ_REMOVE(&files, id, next); 1393 TAILQ_INSERT_TAIL(preferred, id, next); 1394 found = 1; 1395 break; 1396 } 1397 } 1398 /* If IdentitiesOnly set and key not found then don't use it */ 1399 if (!found && options.identities_only) { 1400 TAILQ_REMOVE(&files, id, next); 1401 explicit_bzero(id, sizeof(*id)); 1402 free(id); 1403 } 1404 } 1405 /* append remaining keys from the config file */ 1406 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1407 TAILQ_REMOVE(&files, id, next); 1408 TAILQ_INSERT_TAIL(preferred, id, next); 1409 } 1410 /* finally, filter by PubkeyAcceptedKeyTypes */ 1411 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1412 if (id->key != NULL && 1413 match_pattern_list(sshkey_ssh_name(id->key), 1414 options.pubkey_key_types, 0) != 1) { 1415 debug("Skipping %s key %s - " 1416 "not in PubkeyAcceptedKeyTypes", 1417 sshkey_ssh_name(id->key), id->filename); 1418 TAILQ_REMOVE(preferred, id, next); 1419 sshkey_free(id->key); 1420 free(id->filename); 1421 memset(id, 0, sizeof(*id)); 1422 continue; 1423 } 1424 debug2("key: %s (%p)%s%s", id->filename, id->key, 1425 id->userprovided ? ", explicit" : "", 1426 id->agent_fd != -1 ? ", agent" : ""); 1427 } 1428 } 1429 1430 static void 1431 pubkey_cleanup(Authctxt *authctxt) 1432 { 1433 Identity *id; 1434 1435 if (authctxt->agent_fd != -1) 1436 ssh_close_authentication_socket(authctxt->agent_fd); 1437 for (id = TAILQ_FIRST(&authctxt->keys); id; 1438 id = TAILQ_FIRST(&authctxt->keys)) { 1439 TAILQ_REMOVE(&authctxt->keys, id, next); 1440 sshkey_free(id->key); 1441 free(id->filename); 1442 free(id); 1443 } 1444 } 1445 1446 static void 1447 pubkey_reset(Authctxt *authctxt) 1448 { 1449 Identity *id; 1450 1451 TAILQ_FOREACH(id, &authctxt->keys, next) 1452 id->tried = 0; 1453 } 1454 1455 static int 1456 try_identity(Identity *id) 1457 { 1458 if (!id->key) 1459 return (0); 1460 if (key_type_plain(id->key->type) == KEY_RSA && 1461 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1462 debug("Skipped %s key %s for RSA/MD5 server", 1463 key_type(id->key), id->filename); 1464 return (0); 1465 } 1466 return 1; 1467 } 1468 1469 int 1470 userauth_pubkey(Authctxt *authctxt) 1471 { 1472 Identity *id; 1473 int sent = 0; 1474 char *fp; 1475 1476 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1477 if (id->tried++) 1478 return (0); 1479 /* move key to the end of the queue */ 1480 TAILQ_REMOVE(&authctxt->keys, id, next); 1481 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1482 /* 1483 * send a test message if we have the public key. for 1484 * encrypted keys we cannot do this and have to load the 1485 * private key instead 1486 */ 1487 if (id->key != NULL) { 1488 if (try_identity(id)) { 1489 if ((fp = sshkey_fingerprint(id->key, 1490 options.fingerprint_hash, 1491 SSH_FP_DEFAULT)) == NULL) { 1492 error("%s: sshkey_fingerprint failed", 1493 __func__); 1494 return 0; 1495 } 1496 debug("Offering public key: %s %s %s", 1497 sshkey_type(id->key), fp, id->filename); 1498 free(fp); 1499 sent = send_pubkey_test(authctxt, id); 1500 } 1501 } else { 1502 debug("Trying private key: %s", id->filename); 1503 id->key = load_identity_file(id); 1504 if (id->key != NULL) { 1505 if (try_identity(id)) { 1506 id->isprivate = 1; 1507 sent = sign_and_send_pubkey( 1508 authctxt, id); 1509 } 1510 key_free(id->key); 1511 id->key = NULL; 1512 id->isprivate = 0; 1513 } 1514 } 1515 if (sent) 1516 return (sent); 1517 } 1518 return (0); 1519 } 1520 1521 /* 1522 * Send userauth request message specifying keyboard-interactive method. 1523 */ 1524 int 1525 userauth_kbdint(Authctxt *authctxt) 1526 { 1527 static int attempt = 0; 1528 1529 if (attempt++ >= options.number_of_password_prompts) 1530 return 0; 1531 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1532 if (attempt > 1 && !authctxt->info_req_seen) { 1533 debug3("userauth_kbdint: disable: no info_req_seen"); 1534 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1535 return 0; 1536 } 1537 1538 debug2("userauth_kbdint"); 1539 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1540 packet_put_cstring(authctxt->server_user); 1541 packet_put_cstring(authctxt->service); 1542 packet_put_cstring(authctxt->method->name); 1543 packet_put_cstring(""); /* lang */ 1544 packet_put_cstring(options.kbd_interactive_devices ? 1545 options.kbd_interactive_devices : ""); 1546 packet_send(); 1547 1548 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1549 return 1; 1550 } 1551 1552 /* 1553 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1554 */ 1555 int 1556 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1557 { 1558 Authctxt *authctxt = ssh->authctxt; 1559 char *name, *inst, *lang, *prompt, *response; 1560 u_int num_prompts, i; 1561 int echo = 0; 1562 1563 debug2("input_userauth_info_req"); 1564 1565 if (authctxt == NULL) 1566 fatal("input_userauth_info_req: no authentication context"); 1567 1568 authctxt->info_req_seen = 1; 1569 1570 name = packet_get_string(NULL); 1571 inst = packet_get_string(NULL); 1572 lang = packet_get_string(NULL); 1573 if (strlen(name) > 0) 1574 logit("%s", name); 1575 if (strlen(inst) > 0) 1576 logit("%s", inst); 1577 free(name); 1578 free(inst); 1579 free(lang); 1580 1581 num_prompts = packet_get_int(); 1582 /* 1583 * Begin to build info response packet based on prompts requested. 1584 * We commit to providing the correct number of responses, so if 1585 * further on we run into a problem that prevents this, we have to 1586 * be sure and clean this up and send a correct error response. 1587 */ 1588 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1589 packet_put_int(num_prompts); 1590 1591 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1592 for (i = 0; i < num_prompts; i++) { 1593 prompt = packet_get_string(NULL); 1594 echo = packet_get_char(); 1595 1596 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1597 1598 packet_put_cstring(response); 1599 explicit_bzero(response, strlen(response)); 1600 free(response); 1601 free(prompt); 1602 } 1603 packet_check_eom(); /* done with parsing incoming message. */ 1604 1605 packet_add_padding(64); 1606 packet_send(); 1607 return 0; 1608 } 1609 1610 static int 1611 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1612 const u_char *data, size_t datalen) 1613 { 1614 struct sshbuf *b; 1615 struct stat st; 1616 pid_t pid; 1617 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1618 u_char rversion = 0, version = 2; 1619 void (*osigchld)(int); 1620 1621 *sigp = NULL; 1622 *lenp = 0; 1623 1624 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1625 error("%s: not installed: %s", __func__, strerror(errno)); 1626 return -1; 1627 } 1628 if (fflush(stdout) != 0) { 1629 error("%s: fflush: %s", __func__, strerror(errno)); 1630 return -1; 1631 } 1632 if (pipe(to) < 0) { 1633 error("%s: pipe: %s", __func__, strerror(errno)); 1634 return -1; 1635 } 1636 if (pipe(from) < 0) { 1637 error("%s: pipe: %s", __func__, strerror(errno)); 1638 return -1; 1639 } 1640 if ((pid = fork()) < 0) { 1641 error("%s: fork: %s", __func__, strerror(errno)); 1642 return -1; 1643 } 1644 osigchld = signal(SIGCHLD, SIG_DFL); 1645 if (pid == 0) { 1646 /* keep the socket on exec */ 1647 fcntl(sock, F_SETFD, 0); 1648 permanently_drop_suid(getuid()); 1649 close(from[0]); 1650 if (dup2(from[1], STDOUT_FILENO) < 0) 1651 fatal("%s: dup2: %s", __func__, strerror(errno)); 1652 close(to[1]); 1653 if (dup2(to[0], STDIN_FILENO) < 0) 1654 fatal("%s: dup2: %s", __func__, strerror(errno)); 1655 close(from[1]); 1656 close(to[0]); 1657 /* Close everything but stdio and the socket */ 1658 for (i = STDERR_FILENO + 1; i < sock; i++) 1659 close(i); 1660 closefrom(sock + 1); 1661 debug3("%s: [child] pid=%ld, exec %s", 1662 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1663 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1664 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1665 strerror(errno)); 1666 } 1667 close(from[1]); 1668 close(to[0]); 1669 1670 if ((b = sshbuf_new()) == NULL) 1671 fatal("%s: sshbuf_new failed", __func__); 1672 /* send # of sock, data to be signed */ 1673 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1674 (r = sshbuf_put_string(b, data, datalen)) != 0) 1675 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1676 if (ssh_msg_send(to[1], version, b) == -1) 1677 fatal("%s: couldn't send request", __func__); 1678 sshbuf_reset(b); 1679 r = ssh_msg_recv(from[0], b); 1680 close(from[0]); 1681 close(to[1]); 1682 if (r < 0) { 1683 error("%s: no reply", __func__); 1684 goto fail; 1685 } 1686 1687 errno = 0; 1688 while (waitpid(pid, &status, 0) < 0) { 1689 if (errno != EINTR) { 1690 error("%s: waitpid %ld: %s", 1691 __func__, (long)pid, strerror(errno)); 1692 goto fail; 1693 } 1694 } 1695 if (!WIFEXITED(status)) { 1696 error("%s: exited abnormally", __func__); 1697 goto fail; 1698 } 1699 if (WEXITSTATUS(status) != 0) { 1700 error("%s: exited with status %d", 1701 __func__, WEXITSTATUS(status)); 1702 goto fail; 1703 } 1704 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1705 error("%s: buffer error: %s", __func__, ssh_err(r)); 1706 goto fail; 1707 } 1708 if (rversion != version) { 1709 error("%s: bad version", __func__); 1710 goto fail; 1711 } 1712 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1713 error("%s: buffer error: %s", __func__, ssh_err(r)); 1714 fail: 1715 signal(SIGCHLD, osigchld); 1716 sshbuf_free(b); 1717 return -1; 1718 } 1719 signal(SIGCHLD, osigchld); 1720 sshbuf_free(b); 1721 1722 return 0; 1723 } 1724 1725 int 1726 userauth_hostbased(Authctxt *authctxt) 1727 { 1728 struct ssh *ssh = active_state; 1729 struct sshkey *private = NULL; 1730 struct sshbuf *b = NULL; 1731 u_char *sig = NULL, *keyblob = NULL; 1732 char *fp = NULL, *chost = NULL, *lname = NULL; 1733 size_t siglen = 0, keylen = 0; 1734 int i, r, success = 0; 1735 1736 if (authctxt->ktypes == NULL) { 1737 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1738 authctxt->ktypes = authctxt->oktypes; 1739 } 1740 1741 /* 1742 * Work through each listed type pattern in HostbasedKeyTypes, 1743 * trying each hostkey that matches the type in turn. 1744 */ 1745 for (;;) { 1746 if (authctxt->active_ktype == NULL) 1747 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1748 if (authctxt->active_ktype == NULL || 1749 *authctxt->active_ktype == '\0') 1750 break; 1751 debug3("%s: trying key type %s", __func__, 1752 authctxt->active_ktype); 1753 1754 /* check for a useful key */ 1755 private = NULL; 1756 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1757 if (authctxt->sensitive->keys[i] == NULL || 1758 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1759 continue; 1760 if (match_pattern_list( 1761 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1762 authctxt->active_ktype, 0) != 1) 1763 continue; 1764 /* we take and free the key */ 1765 private = authctxt->sensitive->keys[i]; 1766 authctxt->sensitive->keys[i] = NULL; 1767 break; 1768 } 1769 /* Found one */ 1770 if (private != NULL) 1771 break; 1772 /* No more keys of this type; advance */ 1773 authctxt->active_ktype = NULL; 1774 } 1775 if (private == NULL) { 1776 free(authctxt->oktypes); 1777 authctxt->oktypes = authctxt->ktypes = NULL; 1778 authctxt->active_ktype = NULL; 1779 debug("No more client hostkeys for hostbased authentication."); 1780 goto out; 1781 } 1782 1783 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1784 SSH_FP_DEFAULT)) == NULL) { 1785 error("%s: sshkey_fingerprint failed", __func__); 1786 goto out; 1787 } 1788 debug("%s: trying hostkey %s %s", 1789 __func__, sshkey_ssh_name(private), fp); 1790 1791 /* figure out a name for the client host */ 1792 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1793 error("%s: cannot get local ipaddr/name", __func__); 1794 goto out; 1795 } 1796 1797 /* XXX sshbuf_put_stringf? */ 1798 xasprintf(&chost, "%s.", lname); 1799 debug2("%s: chost %s", __func__, chost); 1800 1801 /* construct data */ 1802 if ((b = sshbuf_new()) == NULL) { 1803 error("%s: sshbuf_new failed", __func__); 1804 goto out; 1805 } 1806 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1807 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1808 goto out; 1809 } 1810 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1811 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1812 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1813 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1814 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1815 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1816 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1817 (r = sshbuf_put_cstring(b, chost)) != 0 || 1818 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1819 error("%s: buffer error: %s", __func__, ssh_err(r)); 1820 goto out; 1821 } 1822 1823 #ifdef DEBUG_PK 1824 sshbuf_dump(b, stderr); 1825 #endif 1826 if (authctxt->sensitive->external_keysign) 1827 r = ssh_keysign(private, &sig, &siglen, 1828 sshbuf_ptr(b), sshbuf_len(b)); 1829 else if ((r = sshkey_sign(private, &sig, &siglen, 1830 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1831 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1832 if (r != 0) { 1833 error("sign using hostkey %s %s failed", 1834 sshkey_ssh_name(private), fp); 1835 goto out; 1836 } 1837 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1838 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1839 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1840 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1841 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1842 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1843 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1844 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1845 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1846 (r = sshpkt_send(ssh)) != 0) { 1847 error("%s: packet error: %s", __func__, ssh_err(r)); 1848 goto out; 1849 } 1850 success = 1; 1851 1852 out: 1853 if (sig != NULL) { 1854 explicit_bzero(sig, siglen); 1855 free(sig); 1856 } 1857 free(keyblob); 1858 free(lname); 1859 free(fp); 1860 free(chost); 1861 sshkey_free(private); 1862 sshbuf_free(b); 1863 1864 return success; 1865 } 1866 1867 /* find auth method */ 1868 1869 /* 1870 * given auth method name, if configurable options permit this method fill 1871 * in auth_ident field and return true, otherwise return false. 1872 */ 1873 static int 1874 authmethod_is_enabled(Authmethod *method) 1875 { 1876 if (method == NULL) 1877 return 0; 1878 /* return false if options indicate this method is disabled */ 1879 if (method->enabled == NULL || *method->enabled == 0) 1880 return 0; 1881 /* return false if batch mode is enabled but method needs interactive mode */ 1882 if (method->batch_flag != NULL && *method->batch_flag != 0) 1883 return 0; 1884 return 1; 1885 } 1886 1887 static Authmethod * 1888 authmethod_lookup(const char *name) 1889 { 1890 Authmethod *method = NULL; 1891 if (name != NULL) 1892 for (method = authmethods; method->name != NULL; method++) 1893 if (strcmp(name, method->name) == 0) 1894 return method; 1895 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1896 return NULL; 1897 } 1898 1899 /* XXX internal state */ 1900 static Authmethod *current = NULL; 1901 static char *supported = NULL; 1902 static char *preferred = NULL; 1903 1904 /* 1905 * Given the authentication method list sent by the server, return the 1906 * next method we should try. If the server initially sends a nil list, 1907 * use a built-in default list. 1908 */ 1909 static Authmethod * 1910 authmethod_get(char *authlist) 1911 { 1912 char *name = NULL; 1913 u_int next; 1914 1915 /* Use a suitable default if we're passed a nil list. */ 1916 if (authlist == NULL || strlen(authlist) == 0) 1917 authlist = options.preferred_authentications; 1918 1919 if (supported == NULL || strcmp(authlist, supported) != 0) { 1920 debug3("start over, passed a different list %s", authlist); 1921 free(supported); 1922 supported = xstrdup(authlist); 1923 preferred = options.preferred_authentications; 1924 debug3("preferred %s", preferred); 1925 current = NULL; 1926 } else if (current != NULL && authmethod_is_enabled(current)) 1927 return current; 1928 1929 for (;;) { 1930 if ((name = match_list(preferred, supported, &next)) == NULL) { 1931 debug("No more authentication methods to try."); 1932 current = NULL; 1933 return NULL; 1934 } 1935 preferred += next; 1936 debug3("authmethod_lookup %s", name); 1937 debug3("remaining preferred: %s", preferred); 1938 if ((current = authmethod_lookup(name)) != NULL && 1939 authmethod_is_enabled(current)) { 1940 debug3("authmethod_is_enabled %s", name); 1941 debug("Next authentication method: %s", name); 1942 free(name); 1943 return current; 1944 } 1945 free(name); 1946 } 1947 } 1948 1949 static char * 1950 authmethods_get(void) 1951 { 1952 Authmethod *method = NULL; 1953 Buffer b; 1954 char *list; 1955 1956 buffer_init(&b); 1957 for (method = authmethods; method->name != NULL; method++) { 1958 if (authmethod_is_enabled(method)) { 1959 if (buffer_len(&b) > 0) 1960 buffer_append(&b, ",", 1); 1961 buffer_append(&b, method->name, strlen(method->name)); 1962 } 1963 } 1964 if ((list = sshbuf_dup_string(&b)) == NULL) 1965 fatal("%s: sshbuf_dup_string failed", __func__); 1966 buffer_free(&b); 1967 return list; 1968 } 1969 1970