1 /* $OpenBSD: sshconnect2.c,v 1.270 2018/03/24 19:28:43 markus 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 (sshkey_is_cert(key)) 1010 return 0; 1011 if ((r = sshkey_sigtype(sig, len, &sigtype)) != 0) 1012 return r; 1013 if (strcmp(sigtype, alg) != 0) { 1014 logit("warning: agent returned different signature type %s " 1015 "(expected %s)", sigtype, alg); 1016 } 1017 free(sigtype); 1018 /* Incorrect signature types aren't an error ... yet */ 1019 return 0; 1020 } 1021 1022 static int 1023 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1024 const u_char *data, size_t datalen, u_int compat) 1025 { 1026 struct sshkey *prv; 1027 int r; 1028 1029 /* the agent supports this key */ 1030 if (id->key != NULL && id->agent_fd != -1) { 1031 if ((r = ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1032 data, datalen, key_sign_encode(id->key), compat)) != 0 || 1033 (r = check_sigtype(id->key, *sigp, *lenp)) != 0) 1034 return r; 1035 return 0; 1036 } 1037 1038 /* 1039 * we have already loaded the private key or 1040 * the private key is stored in external hardware 1041 */ 1042 if (id->key != NULL && 1043 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) 1044 return (sshkey_sign(id->key, sigp, lenp, data, datalen, 1045 key_sign_encode(id->key), compat)); 1046 1047 /* load the private key from the file */ 1048 if ((prv = load_identity_file(id)) == NULL) 1049 return SSH_ERR_KEY_NOT_FOUND; 1050 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1051 error("%s: private key %s contents do not match public", 1052 __func__, id->filename); 1053 return SSH_ERR_KEY_NOT_FOUND; 1054 } 1055 r = sshkey_sign(prv, sigp, lenp, data, datalen, 1056 key_sign_encode(prv), compat); 1057 sshkey_free(prv); 1058 return r; 1059 } 1060 1061 static int 1062 id_filename_matches(Identity *id, Identity *private_id) 1063 { 1064 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1065 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1066 size_t i, slen; 1067 1068 if (strcmp(id->filename, private_id->filename) == 0) 1069 return 1; 1070 for (i = 0; suffixes[i]; i++) { 1071 slen = strlen(suffixes[i]); 1072 if (len > slen && plen == len - slen && 1073 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1074 memcmp(id->filename, private_id->filename, plen) == 0) 1075 return 1; 1076 } 1077 return 0; 1078 } 1079 1080 static int 1081 sign_and_send_pubkey(Authctxt *authctxt, Identity *id) 1082 { 1083 Buffer b; 1084 Identity *private_id; 1085 u_char *blob, *signature; 1086 size_t slen; 1087 u_int bloblen, skip = 0; 1088 int matched, ret = -1, have_sig = 1; 1089 char *fp; 1090 1091 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1092 SSH_FP_DEFAULT)) == NULL) 1093 return 0; 1094 debug3("%s: %s %s", __func__, key_type(id->key), fp); 1095 free(fp); 1096 1097 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1098 /* we cannot handle this key */ 1099 debug3("sign_and_send_pubkey: cannot handle key"); 1100 return 0; 1101 } 1102 /* data to be signed */ 1103 buffer_init(&b); 1104 if (datafellows & SSH_OLD_SESSIONID) { 1105 buffer_append(&b, session_id2, session_id2_len); 1106 skip = session_id2_len; 1107 } else { 1108 buffer_put_string(&b, session_id2, session_id2_len); 1109 skip = buffer_len(&b); 1110 } 1111 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); 1112 buffer_put_cstring(&b, authctxt->server_user); 1113 buffer_put_cstring(&b, authctxt->service); 1114 buffer_put_cstring(&b, authctxt->method->name); 1115 buffer_put_char(&b, have_sig); 1116 buffer_put_cstring(&b, key_sign_encode(id->key)); 1117 buffer_put_string(&b, blob, bloblen); 1118 1119 /* 1120 * If the key is an certificate, try to find a matching private key 1121 * and use it to complete the signature. 1122 * If no such private key exists, fall back to trying the certificate 1123 * key itself in case it has a private half already loaded. 1124 */ 1125 if (key_is_cert(id->key)) { 1126 matched = 0; 1127 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1128 if (sshkey_equal_public(id->key, private_id->key) && 1129 id->key->type != private_id->key->type) { 1130 id = private_id; 1131 matched = 1; 1132 break; 1133 } 1134 } 1135 /* 1136 * Exact key matches are preferred, but also allow 1137 * filename matches for non-PKCS#11/agent keys that 1138 * didn't load public keys. This supports the case 1139 * of keeping just a private key file and public 1140 * certificate on disk. 1141 */ 1142 if (!matched && !id->isprivate && id->agent_fd == -1 && 1143 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1144 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1145 if (private_id->key == NULL && 1146 id_filename_matches(id, private_id)) { 1147 id = private_id; 1148 matched = 1; 1149 break; 1150 } 1151 } 1152 } 1153 if (matched) { 1154 debug2("%s: using private key \"%s\"%s for " 1155 "certificate", __func__, id->filename, 1156 id->agent_fd != -1 ? " from agent" : ""); 1157 } else { 1158 debug("%s: no separate private key for certificate " 1159 "\"%s\"", __func__, id->filename); 1160 } 1161 } 1162 1163 /* generate signature */ 1164 ret = identity_sign(id, &signature, &slen, 1165 buffer_ptr(&b), buffer_len(&b), datafellows); 1166 if (ret != 0) { 1167 if (ret != SSH_ERR_KEY_NOT_FOUND) 1168 error("%s: signing failed: %s", __func__, ssh_err(ret)); 1169 free(blob); 1170 buffer_free(&b); 1171 return 0; 1172 } 1173 #ifdef DEBUG_PK 1174 buffer_dump(&b); 1175 #endif 1176 free(blob); 1177 1178 /* append signature */ 1179 buffer_put_string(&b, signature, slen); 1180 free(signature); 1181 1182 /* skip session id and packet type */ 1183 if (buffer_len(&b) < skip + 1) 1184 fatal("userauth_pubkey: internal error"); 1185 buffer_consume(&b, skip + 1); 1186 1187 /* put remaining data from buffer into packet */ 1188 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1189 packet_put_raw(buffer_ptr(&b), buffer_len(&b)); 1190 buffer_free(&b); 1191 packet_send(); 1192 1193 return 1; 1194 } 1195 1196 static int 1197 send_pubkey_test(Authctxt *authctxt, Identity *id) 1198 { 1199 u_char *blob; 1200 u_int bloblen, have_sig = 0; 1201 1202 debug3("send_pubkey_test"); 1203 1204 if (key_to_blob(id->key, &blob, &bloblen) == 0) { 1205 /* we cannot handle this key */ 1206 debug3("send_pubkey_test: cannot handle key"); 1207 return 0; 1208 } 1209 /* register callback for USERAUTH_PK_OK message */ 1210 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1211 1212 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1213 packet_put_cstring(authctxt->server_user); 1214 packet_put_cstring(authctxt->service); 1215 packet_put_cstring(authctxt->method->name); 1216 packet_put_char(have_sig); 1217 packet_put_cstring(key_sign_encode(id->key)); 1218 packet_put_string(blob, bloblen); 1219 free(blob); 1220 packet_send(); 1221 return 1; 1222 } 1223 1224 static struct sshkey * 1225 load_identity_file(Identity *id) 1226 { 1227 struct sshkey *private = NULL; 1228 char prompt[300], *passphrase, *comment; 1229 int r, perm_ok = 0, quit = 0, i; 1230 struct stat st; 1231 1232 if (stat(id->filename, &st) < 0) { 1233 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1234 id->filename, strerror(errno)); 1235 return NULL; 1236 } 1237 snprintf(prompt, sizeof prompt, 1238 "Enter passphrase for key '%.100s': ", id->filename); 1239 for (i = 0; i <= options.number_of_password_prompts; i++) { 1240 if (i == 0) 1241 passphrase = ""; 1242 else { 1243 passphrase = read_passphrase(prompt, 0); 1244 if (*passphrase == '\0') { 1245 debug2("no passphrase given, try next key"); 1246 free(passphrase); 1247 break; 1248 } 1249 } 1250 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1251 passphrase, &private, &comment, &perm_ok))) { 1252 case 0: 1253 break; 1254 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1255 if (options.batch_mode) { 1256 quit = 1; 1257 break; 1258 } 1259 if (i != 0) 1260 debug2("bad passphrase given, try again..."); 1261 break; 1262 case SSH_ERR_SYSTEM_ERROR: 1263 if (errno == ENOENT) { 1264 debug2("Load key \"%s\": %s", 1265 id->filename, ssh_err(r)); 1266 quit = 1; 1267 break; 1268 } 1269 /* FALLTHROUGH */ 1270 default: 1271 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1272 quit = 1; 1273 break; 1274 } 1275 if (!quit && private != NULL && id->agent_fd == -1 && 1276 !(id->key && id->isprivate)) 1277 maybe_add_key_to_agent(id->filename, private, comment, 1278 passphrase); 1279 if (i > 0) { 1280 explicit_bzero(passphrase, strlen(passphrase)); 1281 free(passphrase); 1282 } 1283 free(comment); 1284 if (private != NULL || quit) 1285 break; 1286 } 1287 return private; 1288 } 1289 1290 /* 1291 * try keys in the following order: 1292 * 1. certificates listed in the config file 1293 * 2. other input certificates 1294 * 3. agent keys that are found in the config file 1295 * 4. other agent keys 1296 * 5. keys that are only listed in the config file 1297 */ 1298 static void 1299 pubkey_prepare(Authctxt *authctxt) 1300 { 1301 struct identity *id, *id2, *tmp; 1302 struct idlist agent, files, *preferred; 1303 struct sshkey *key; 1304 int agent_fd = -1, i, r, found; 1305 size_t j; 1306 struct ssh_identitylist *idlist; 1307 1308 TAILQ_INIT(&agent); /* keys from the agent */ 1309 TAILQ_INIT(&files); /* keys from the config file */ 1310 preferred = &authctxt->keys; 1311 TAILQ_INIT(preferred); /* preferred order of keys */ 1312 1313 /* list of keys stored in the filesystem and PKCS#11 */ 1314 for (i = 0; i < options.num_identity_files; i++) { 1315 key = options.identity_keys[i]; 1316 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1317 continue; 1318 options.identity_keys[i] = NULL; 1319 id = xcalloc(1, sizeof(*id)); 1320 id->agent_fd = -1; 1321 id->key = key; 1322 id->filename = xstrdup(options.identity_files[i]); 1323 id->userprovided = options.identity_file_userprovided[i]; 1324 TAILQ_INSERT_TAIL(&files, id, next); 1325 } 1326 /* list of certificates specified by user */ 1327 for (i = 0; i < options.num_certificate_files; i++) { 1328 key = options.certificates[i]; 1329 if (!key_is_cert(key) || key->cert == NULL || 1330 key->cert->type != SSH2_CERT_TYPE_USER) 1331 continue; 1332 id = xcalloc(1, sizeof(*id)); 1333 id->agent_fd = -1; 1334 id->key = key; 1335 id->filename = xstrdup(options.certificate_files[i]); 1336 id->userprovided = options.certificate_file_userprovided[i]; 1337 TAILQ_INSERT_TAIL(preferred, id, next); 1338 } 1339 /* list of keys supported by the agent */ 1340 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1341 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1342 debug("%s: ssh_get_authentication_socket: %s", 1343 __func__, ssh_err(r)); 1344 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1345 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1346 debug("%s: ssh_fetch_identitylist: %s", 1347 __func__, ssh_err(r)); 1348 close(agent_fd); 1349 } else { 1350 for (j = 0; j < idlist->nkeys; j++) { 1351 found = 0; 1352 TAILQ_FOREACH(id, &files, next) { 1353 /* 1354 * agent keys from the config file are 1355 * preferred 1356 */ 1357 if (sshkey_equal(idlist->keys[j], id->key)) { 1358 TAILQ_REMOVE(&files, id, next); 1359 TAILQ_INSERT_TAIL(preferred, id, next); 1360 id->agent_fd = agent_fd; 1361 found = 1; 1362 break; 1363 } 1364 } 1365 if (!found && !options.identities_only) { 1366 id = xcalloc(1, sizeof(*id)); 1367 /* XXX "steals" key/comment from idlist */ 1368 id->key = idlist->keys[j]; 1369 id->filename = idlist->comments[j]; 1370 idlist->keys[j] = NULL; 1371 idlist->comments[j] = NULL; 1372 id->agent_fd = agent_fd; 1373 TAILQ_INSERT_TAIL(&agent, id, next); 1374 } 1375 } 1376 ssh_free_identitylist(idlist); 1377 /* append remaining agent keys */ 1378 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1379 TAILQ_REMOVE(&agent, id, next); 1380 TAILQ_INSERT_TAIL(preferred, id, next); 1381 } 1382 authctxt->agent_fd = agent_fd; 1383 } 1384 /* Prefer PKCS11 keys that are explicitly listed */ 1385 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1386 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1387 continue; 1388 found = 0; 1389 TAILQ_FOREACH(id2, &files, next) { 1390 if (id2->key == NULL || 1391 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1392 continue; 1393 if (sshkey_equal(id->key, id2->key)) { 1394 TAILQ_REMOVE(&files, id, next); 1395 TAILQ_INSERT_TAIL(preferred, id, next); 1396 found = 1; 1397 break; 1398 } 1399 } 1400 /* If IdentitiesOnly set and key not found then don't use it */ 1401 if (!found && options.identities_only) { 1402 TAILQ_REMOVE(&files, id, next); 1403 explicit_bzero(id, sizeof(*id)); 1404 free(id); 1405 } 1406 } 1407 /* append remaining keys from the config file */ 1408 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1409 TAILQ_REMOVE(&files, id, next); 1410 TAILQ_INSERT_TAIL(preferred, id, next); 1411 } 1412 /* finally, filter by PubkeyAcceptedKeyTypes */ 1413 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1414 if (id->key != NULL && 1415 match_pattern_list(sshkey_ssh_name(id->key), 1416 options.pubkey_key_types, 0) != 1) { 1417 debug("Skipping %s key %s - " 1418 "not in PubkeyAcceptedKeyTypes", 1419 sshkey_ssh_name(id->key), id->filename); 1420 TAILQ_REMOVE(preferred, id, next); 1421 sshkey_free(id->key); 1422 free(id->filename); 1423 memset(id, 0, sizeof(*id)); 1424 continue; 1425 } 1426 debug2("key: %s (%p)%s%s", id->filename, id->key, 1427 id->userprovided ? ", explicit" : "", 1428 id->agent_fd != -1 ? ", agent" : ""); 1429 } 1430 } 1431 1432 static void 1433 pubkey_cleanup(Authctxt *authctxt) 1434 { 1435 Identity *id; 1436 1437 if (authctxt->agent_fd != -1) 1438 ssh_close_authentication_socket(authctxt->agent_fd); 1439 for (id = TAILQ_FIRST(&authctxt->keys); id; 1440 id = TAILQ_FIRST(&authctxt->keys)) { 1441 TAILQ_REMOVE(&authctxt->keys, id, next); 1442 sshkey_free(id->key); 1443 free(id->filename); 1444 free(id); 1445 } 1446 } 1447 1448 static void 1449 pubkey_reset(Authctxt *authctxt) 1450 { 1451 Identity *id; 1452 1453 TAILQ_FOREACH(id, &authctxt->keys, next) 1454 id->tried = 0; 1455 } 1456 1457 static int 1458 try_identity(Identity *id) 1459 { 1460 if (!id->key) 1461 return (0); 1462 if (key_type_plain(id->key->type) == KEY_RSA && 1463 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1464 debug("Skipped %s key %s for RSA/MD5 server", 1465 key_type(id->key), id->filename); 1466 return (0); 1467 } 1468 return 1; 1469 } 1470 1471 int 1472 userauth_pubkey(Authctxt *authctxt) 1473 { 1474 Identity *id; 1475 int sent = 0; 1476 char *fp; 1477 1478 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1479 if (id->tried++) 1480 return (0); 1481 /* move key to the end of the queue */ 1482 TAILQ_REMOVE(&authctxt->keys, id, next); 1483 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1484 /* 1485 * send a test message if we have the public key. for 1486 * encrypted keys we cannot do this and have to load the 1487 * private key instead 1488 */ 1489 if (id->key != NULL) { 1490 if (try_identity(id)) { 1491 if ((fp = sshkey_fingerprint(id->key, 1492 options.fingerprint_hash, 1493 SSH_FP_DEFAULT)) == NULL) { 1494 error("%s: sshkey_fingerprint failed", 1495 __func__); 1496 return 0; 1497 } 1498 debug("Offering public key: %s %s %s", 1499 sshkey_type(id->key), fp, id->filename); 1500 free(fp); 1501 sent = send_pubkey_test(authctxt, id); 1502 } 1503 } else { 1504 debug("Trying private key: %s", id->filename); 1505 id->key = load_identity_file(id); 1506 if (id->key != NULL) { 1507 if (try_identity(id)) { 1508 id->isprivate = 1; 1509 sent = sign_and_send_pubkey( 1510 authctxt, id); 1511 } 1512 key_free(id->key); 1513 id->key = NULL; 1514 id->isprivate = 0; 1515 } 1516 } 1517 if (sent) 1518 return (sent); 1519 } 1520 return (0); 1521 } 1522 1523 /* 1524 * Send userauth request message specifying keyboard-interactive method. 1525 */ 1526 int 1527 userauth_kbdint(Authctxt *authctxt) 1528 { 1529 static int attempt = 0; 1530 1531 if (attempt++ >= options.number_of_password_prompts) 1532 return 0; 1533 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1534 if (attempt > 1 && !authctxt->info_req_seen) { 1535 debug3("userauth_kbdint: disable: no info_req_seen"); 1536 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1537 return 0; 1538 } 1539 1540 debug2("userauth_kbdint"); 1541 packet_start(SSH2_MSG_USERAUTH_REQUEST); 1542 packet_put_cstring(authctxt->server_user); 1543 packet_put_cstring(authctxt->service); 1544 packet_put_cstring(authctxt->method->name); 1545 packet_put_cstring(""); /* lang */ 1546 packet_put_cstring(options.kbd_interactive_devices ? 1547 options.kbd_interactive_devices : ""); 1548 packet_send(); 1549 1550 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1551 return 1; 1552 } 1553 1554 /* 1555 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1556 */ 1557 int 1558 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1559 { 1560 Authctxt *authctxt = ssh->authctxt; 1561 char *name, *inst, *lang, *prompt, *response; 1562 u_int num_prompts, i; 1563 int echo = 0; 1564 1565 debug2("input_userauth_info_req"); 1566 1567 if (authctxt == NULL) 1568 fatal("input_userauth_info_req: no authentication context"); 1569 1570 authctxt->info_req_seen = 1; 1571 1572 name = packet_get_string(NULL); 1573 inst = packet_get_string(NULL); 1574 lang = packet_get_string(NULL); 1575 if (strlen(name) > 0) 1576 logit("%s", name); 1577 if (strlen(inst) > 0) 1578 logit("%s", inst); 1579 free(name); 1580 free(inst); 1581 free(lang); 1582 1583 num_prompts = packet_get_int(); 1584 /* 1585 * Begin to build info response packet based on prompts requested. 1586 * We commit to providing the correct number of responses, so if 1587 * further on we run into a problem that prevents this, we have to 1588 * be sure and clean this up and send a correct error response. 1589 */ 1590 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); 1591 packet_put_int(num_prompts); 1592 1593 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1594 for (i = 0; i < num_prompts; i++) { 1595 prompt = packet_get_string(NULL); 1596 echo = packet_get_char(); 1597 1598 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1599 1600 packet_put_cstring(response); 1601 explicit_bzero(response, strlen(response)); 1602 free(response); 1603 free(prompt); 1604 } 1605 packet_check_eom(); /* done with parsing incoming message. */ 1606 1607 packet_add_padding(64); 1608 packet_send(); 1609 return 0; 1610 } 1611 1612 static int 1613 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1614 const u_char *data, size_t datalen) 1615 { 1616 struct sshbuf *b; 1617 struct stat st; 1618 pid_t pid; 1619 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1620 u_char rversion = 0, version = 2; 1621 void (*osigchld)(int); 1622 1623 *sigp = NULL; 1624 *lenp = 0; 1625 1626 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1627 error("%s: not installed: %s", __func__, strerror(errno)); 1628 return -1; 1629 } 1630 if (fflush(stdout) != 0) { 1631 error("%s: fflush: %s", __func__, strerror(errno)); 1632 return -1; 1633 } 1634 if (pipe(to) < 0) { 1635 error("%s: pipe: %s", __func__, strerror(errno)); 1636 return -1; 1637 } 1638 if (pipe(from) < 0) { 1639 error("%s: pipe: %s", __func__, strerror(errno)); 1640 return -1; 1641 } 1642 if ((pid = fork()) < 0) { 1643 error("%s: fork: %s", __func__, strerror(errno)); 1644 return -1; 1645 } 1646 osigchld = signal(SIGCHLD, SIG_DFL); 1647 if (pid == 0) { 1648 /* keep the socket on exec */ 1649 fcntl(sock, F_SETFD, 0); 1650 permanently_drop_suid(getuid()); 1651 close(from[0]); 1652 if (dup2(from[1], STDOUT_FILENO) < 0) 1653 fatal("%s: dup2: %s", __func__, strerror(errno)); 1654 close(to[1]); 1655 if (dup2(to[0], STDIN_FILENO) < 0) 1656 fatal("%s: dup2: %s", __func__, strerror(errno)); 1657 close(from[1]); 1658 close(to[0]); 1659 /* Close everything but stdio and the socket */ 1660 for (i = STDERR_FILENO + 1; i < sock; i++) 1661 close(i); 1662 closefrom(sock + 1); 1663 debug3("%s: [child] pid=%ld, exec %s", 1664 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1665 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1666 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1667 strerror(errno)); 1668 } 1669 close(from[1]); 1670 close(to[0]); 1671 1672 if ((b = sshbuf_new()) == NULL) 1673 fatal("%s: sshbuf_new failed", __func__); 1674 /* send # of sock, data to be signed */ 1675 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1676 (r = sshbuf_put_string(b, data, datalen)) != 0) 1677 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1678 if (ssh_msg_send(to[1], version, b) == -1) 1679 fatal("%s: couldn't send request", __func__); 1680 sshbuf_reset(b); 1681 r = ssh_msg_recv(from[0], b); 1682 close(from[0]); 1683 close(to[1]); 1684 if (r < 0) { 1685 error("%s: no reply", __func__); 1686 goto fail; 1687 } 1688 1689 errno = 0; 1690 while (waitpid(pid, &status, 0) < 0) { 1691 if (errno != EINTR) { 1692 error("%s: waitpid %ld: %s", 1693 __func__, (long)pid, strerror(errno)); 1694 goto fail; 1695 } 1696 } 1697 if (!WIFEXITED(status)) { 1698 error("%s: exited abnormally", __func__); 1699 goto fail; 1700 } 1701 if (WEXITSTATUS(status) != 0) { 1702 error("%s: exited with status %d", 1703 __func__, WEXITSTATUS(status)); 1704 goto fail; 1705 } 1706 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1707 error("%s: buffer error: %s", __func__, ssh_err(r)); 1708 goto fail; 1709 } 1710 if (rversion != version) { 1711 error("%s: bad version", __func__); 1712 goto fail; 1713 } 1714 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1715 error("%s: buffer error: %s", __func__, ssh_err(r)); 1716 fail: 1717 signal(SIGCHLD, osigchld); 1718 sshbuf_free(b); 1719 return -1; 1720 } 1721 signal(SIGCHLD, osigchld); 1722 sshbuf_free(b); 1723 1724 return 0; 1725 } 1726 1727 int 1728 userauth_hostbased(Authctxt *authctxt) 1729 { 1730 struct ssh *ssh = active_state; 1731 struct sshkey *private = NULL; 1732 struct sshbuf *b = NULL; 1733 u_char *sig = NULL, *keyblob = NULL; 1734 char *fp = NULL, *chost = NULL, *lname = NULL; 1735 size_t siglen = 0, keylen = 0; 1736 int i, r, success = 0; 1737 1738 if (authctxt->ktypes == NULL) { 1739 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1740 authctxt->ktypes = authctxt->oktypes; 1741 } 1742 1743 /* 1744 * Work through each listed type pattern in HostbasedKeyTypes, 1745 * trying each hostkey that matches the type in turn. 1746 */ 1747 for (;;) { 1748 if (authctxt->active_ktype == NULL) 1749 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1750 if (authctxt->active_ktype == NULL || 1751 *authctxt->active_ktype == '\0') 1752 break; 1753 debug3("%s: trying key type %s", __func__, 1754 authctxt->active_ktype); 1755 1756 /* check for a useful key */ 1757 private = NULL; 1758 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1759 if (authctxt->sensitive->keys[i] == NULL || 1760 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1761 continue; 1762 if (match_pattern_list( 1763 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1764 authctxt->active_ktype, 0) != 1) 1765 continue; 1766 /* we take and free the key */ 1767 private = authctxt->sensitive->keys[i]; 1768 authctxt->sensitive->keys[i] = NULL; 1769 break; 1770 } 1771 /* Found one */ 1772 if (private != NULL) 1773 break; 1774 /* No more keys of this type; advance */ 1775 authctxt->active_ktype = NULL; 1776 } 1777 if (private == NULL) { 1778 free(authctxt->oktypes); 1779 authctxt->oktypes = authctxt->ktypes = NULL; 1780 authctxt->active_ktype = NULL; 1781 debug("No more client hostkeys for hostbased authentication."); 1782 goto out; 1783 } 1784 1785 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1786 SSH_FP_DEFAULT)) == NULL) { 1787 error("%s: sshkey_fingerprint failed", __func__); 1788 goto out; 1789 } 1790 debug("%s: trying hostkey %s %s", 1791 __func__, sshkey_ssh_name(private), fp); 1792 1793 /* figure out a name for the client host */ 1794 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1795 error("%s: cannot get local ipaddr/name", __func__); 1796 goto out; 1797 } 1798 1799 /* XXX sshbuf_put_stringf? */ 1800 xasprintf(&chost, "%s.", lname); 1801 debug2("%s: chost %s", __func__, chost); 1802 1803 /* construct data */ 1804 if ((b = sshbuf_new()) == NULL) { 1805 error("%s: sshbuf_new failed", __func__); 1806 goto out; 1807 } 1808 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1809 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1810 goto out; 1811 } 1812 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1813 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1814 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1815 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1816 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1817 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 || 1818 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1819 (r = sshbuf_put_cstring(b, chost)) != 0 || 1820 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1821 error("%s: buffer error: %s", __func__, ssh_err(r)); 1822 goto out; 1823 } 1824 1825 #ifdef DEBUG_PK 1826 sshbuf_dump(b, stderr); 1827 #endif 1828 if (authctxt->sensitive->external_keysign) 1829 r = ssh_keysign(private, &sig, &siglen, 1830 sshbuf_ptr(b), sshbuf_len(b)); 1831 else if ((r = sshkey_sign(private, &sig, &siglen, 1832 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0) 1833 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1834 if (r != 0) { 1835 error("sign using hostkey %s %s failed", 1836 sshkey_ssh_name(private), fp); 1837 goto out; 1838 } 1839 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1840 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1841 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1842 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1843 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 || 1844 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 1845 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 1846 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 1847 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 1848 (r = sshpkt_send(ssh)) != 0) { 1849 error("%s: packet error: %s", __func__, ssh_err(r)); 1850 goto out; 1851 } 1852 success = 1; 1853 1854 out: 1855 if (sig != NULL) { 1856 explicit_bzero(sig, siglen); 1857 free(sig); 1858 } 1859 free(keyblob); 1860 free(lname); 1861 free(fp); 1862 free(chost); 1863 sshkey_free(private); 1864 sshbuf_free(b); 1865 1866 return success; 1867 } 1868 1869 /* find auth method */ 1870 1871 /* 1872 * given auth method name, if configurable options permit this method fill 1873 * in auth_ident field and return true, otherwise return false. 1874 */ 1875 static int 1876 authmethod_is_enabled(Authmethod *method) 1877 { 1878 if (method == NULL) 1879 return 0; 1880 /* return false if options indicate this method is disabled */ 1881 if (method->enabled == NULL || *method->enabled == 0) 1882 return 0; 1883 /* return false if batch mode is enabled but method needs interactive mode */ 1884 if (method->batch_flag != NULL && *method->batch_flag != 0) 1885 return 0; 1886 return 1; 1887 } 1888 1889 static Authmethod * 1890 authmethod_lookup(const char *name) 1891 { 1892 Authmethod *method = NULL; 1893 if (name != NULL) 1894 for (method = authmethods; method->name != NULL; method++) 1895 if (strcmp(name, method->name) == 0) 1896 return method; 1897 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 1898 return NULL; 1899 } 1900 1901 /* XXX internal state */ 1902 static Authmethod *current = NULL; 1903 static char *supported = NULL; 1904 static char *preferred = NULL; 1905 1906 /* 1907 * Given the authentication method list sent by the server, return the 1908 * next method we should try. If the server initially sends a nil list, 1909 * use a built-in default list. 1910 */ 1911 static Authmethod * 1912 authmethod_get(char *authlist) 1913 { 1914 char *name = NULL; 1915 u_int next; 1916 1917 /* Use a suitable default if we're passed a nil list. */ 1918 if (authlist == NULL || strlen(authlist) == 0) 1919 authlist = options.preferred_authentications; 1920 1921 if (supported == NULL || strcmp(authlist, supported) != 0) { 1922 debug3("start over, passed a different list %s", authlist); 1923 free(supported); 1924 supported = xstrdup(authlist); 1925 preferred = options.preferred_authentications; 1926 debug3("preferred %s", preferred); 1927 current = NULL; 1928 } else if (current != NULL && authmethod_is_enabled(current)) 1929 return current; 1930 1931 for (;;) { 1932 if ((name = match_list(preferred, supported, &next)) == NULL) { 1933 debug("No more authentication methods to try."); 1934 current = NULL; 1935 return NULL; 1936 } 1937 preferred += next; 1938 debug3("authmethod_lookup %s", name); 1939 debug3("remaining preferred: %s", preferred); 1940 if ((current = authmethod_lookup(name)) != NULL && 1941 authmethod_is_enabled(current)) { 1942 debug3("authmethod_is_enabled %s", name); 1943 debug("Next authentication method: %s", name); 1944 free(name); 1945 return current; 1946 } 1947 free(name); 1948 } 1949 } 1950 1951 static char * 1952 authmethods_get(void) 1953 { 1954 Authmethod *method = NULL; 1955 Buffer b; 1956 char *list; 1957 1958 buffer_init(&b); 1959 for (method = authmethods; method->name != NULL; method++) { 1960 if (authmethod_is_enabled(method)) { 1961 if (buffer_len(&b) > 0) 1962 buffer_append(&b, ",", 1); 1963 buffer_append(&b, method->name, strlen(method->name)); 1964 } 1965 } 1966 if ((list = sshbuf_dup_string(&b)) == NULL) 1967 fatal("%s: sshbuf_dup_string failed", __func__); 1968 buffer_free(&b); 1969 return list; 1970 } 1971 1972