1 /* $OpenBSD: sshconnect2.c,v 1.287 2018/09/14 05:26:27 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 "sshbuf.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "sshkey.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, *all_key; 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 all_key = sshkey_alg_list(0, 0, 1, ','); 176 if (kex_assemble_names(&options.hostkeyalgorithms, 177 KEX_DEFAULT_PK_ALG, all_key) != 0) 178 fatal("%s: kex_assemble_namelist", __func__); 179 free(all_key); 180 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 181 compat_pkalg_proposal(options.hostkeyalgorithms); 182 } else { 183 /* Enforce default */ 184 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 185 /* Prefer algorithms that we already have keys for */ 186 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 187 compat_pkalg_proposal( 188 order_hostkeyalgs(host, hostaddr, port)); 189 } 190 191 if (options.rekey_limit || options.rekey_interval) 192 packet_set_rekey_limits(options.rekey_limit, 193 options.rekey_interval); 194 195 /* start key exchange */ 196 if ((r = kex_setup(active_state, myproposal)) != 0) 197 fatal("kex_setup: %s", ssh_err(r)); 198 kex = active_state->kex; 199 #ifdef WITH_OPENSSL 200 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 201 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 202 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 203 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 204 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 205 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 206 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 207 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 208 #endif 209 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 210 kex->client_version_string=client_version_string; 211 kex->server_version_string=server_version_string; 212 kex->verify_host_key=&verify_host_key_callback; 213 214 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 215 216 /* remove ext-info from the KEX proposals for rekeying */ 217 myproposal[PROPOSAL_KEX_ALGS] = 218 compat_kex_proposal(options.kex_algorithms); 219 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 220 fatal("kex_prop2buf: %s", ssh_err(r)); 221 222 session_id2 = kex->session_id; 223 session_id2_len = kex->session_id_len; 224 225 #ifdef DEBUG_KEXDH 226 /* send 1st encrypted/maced/compressed message */ 227 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 228 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 229 (r = sshpkt_send(ssh)) != 0 || 230 (r = ssh_packet_write_wait(ssh)) != 0) 231 fatal("%s: %s", __func__, ssh_err(r)); 232 #endif 233 } 234 235 /* 236 * Authenticate user 237 */ 238 239 typedef struct cauthctxt Authctxt; 240 typedef struct cauthmethod Authmethod; 241 typedef struct identity Identity; 242 typedef struct idlist Idlist; 243 244 struct identity { 245 TAILQ_ENTRY(identity) next; 246 int agent_fd; /* >=0 if agent supports key */ 247 struct sshkey *key; /* public/private key */ 248 char *filename; /* comment for agent-only keys */ 249 int tried; 250 int isprivate; /* key points to the private key */ 251 int userprovided; 252 }; 253 TAILQ_HEAD(idlist, identity); 254 255 struct cauthctxt { 256 const char *server_user; 257 const char *local_user; 258 const char *host; 259 const char *service; 260 struct cauthmethod *method; 261 sig_atomic_t success; 262 char *authlist; 263 int attempt; 264 /* pubkey */ 265 struct idlist keys; 266 int agent_fd; 267 /* hostbased */ 268 Sensitive *sensitive; 269 char *oktypes, *ktypes; 270 const char *active_ktype; 271 /* kbd-interactive */ 272 int info_req_seen; 273 /* generic */ 274 void *methoddata; 275 }; 276 277 struct cauthmethod { 278 char *name; /* string to compare against server's list */ 279 int (*userauth)(Authctxt *authctxt); 280 void (*cleanup)(Authctxt *authctxt); 281 int *enabled; /* flag in option struct that enables method */ 282 int *batch_flag; /* flag in option struct that disables method */ 283 }; 284 285 int input_userauth_service_accept(int, u_int32_t, struct ssh *); 286 int input_userauth_ext_info(int, u_int32_t, struct ssh *); 287 int input_userauth_success(int, u_int32_t, struct ssh *); 288 int input_userauth_success_unexpected(int, u_int32_t, struct ssh *); 289 int input_userauth_failure(int, u_int32_t, struct ssh *); 290 int input_userauth_banner(int, u_int32_t, struct ssh *); 291 int input_userauth_error(int, u_int32_t, struct ssh *); 292 int input_userauth_info_req(int, u_int32_t, struct ssh *); 293 int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 294 int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 295 296 int userauth_none(Authctxt *); 297 int userauth_pubkey(Authctxt *); 298 int userauth_passwd(Authctxt *); 299 int userauth_kbdint(Authctxt *); 300 int userauth_hostbased(Authctxt *); 301 302 #ifdef GSSAPI 303 int userauth_gssapi(Authctxt *authctxt); 304 int input_gssapi_response(int type, u_int32_t, struct ssh *); 305 int input_gssapi_token(int type, u_int32_t, struct ssh *); 306 int input_gssapi_hash(int type, u_int32_t, struct ssh *); 307 int input_gssapi_error(int, u_int32_t, struct ssh *); 308 int input_gssapi_errtok(int, u_int32_t, struct ssh *); 309 #endif 310 311 void userauth(Authctxt *, char *); 312 313 static int sign_and_send_pubkey(struct ssh *ssh, Authctxt *, Identity *); 314 static void pubkey_prepare(Authctxt *); 315 static void pubkey_cleanup(Authctxt *); 316 static void pubkey_reset(Authctxt *); 317 static struct sshkey *load_identity_file(Identity *); 318 319 static Authmethod *authmethod_get(char *authlist); 320 static Authmethod *authmethod_lookup(const char *name); 321 static char *authmethods_get(void); 322 323 Authmethod authmethods[] = { 324 #ifdef GSSAPI 325 {"gssapi-with-mic", 326 userauth_gssapi, 327 NULL, 328 &options.gss_authentication, 329 NULL}, 330 #endif 331 {"hostbased", 332 userauth_hostbased, 333 NULL, 334 &options.hostbased_authentication, 335 NULL}, 336 {"publickey", 337 userauth_pubkey, 338 NULL, 339 &options.pubkey_authentication, 340 NULL}, 341 {"keyboard-interactive", 342 userauth_kbdint, 343 NULL, 344 &options.kbd_interactive_authentication, 345 &options.batch_mode}, 346 {"password", 347 userauth_passwd, 348 NULL, 349 &options.password_authentication, 350 &options.batch_mode}, 351 {"none", 352 userauth_none, 353 NULL, 354 NULL, 355 NULL}, 356 {NULL, NULL, NULL, NULL, NULL} 357 }; 358 359 void 360 ssh_userauth2(const char *local_user, const char *server_user, char *host, 361 Sensitive *sensitive) 362 { 363 struct ssh *ssh = active_state; 364 Authctxt authctxt; 365 int r; 366 367 if (options.challenge_response_authentication) 368 options.kbd_interactive_authentication = 1; 369 if (options.preferred_authentications == NULL) 370 options.preferred_authentications = authmethods_get(); 371 372 /* setup authentication context */ 373 memset(&authctxt, 0, sizeof(authctxt)); 374 pubkey_prepare(&authctxt); 375 authctxt.server_user = server_user; 376 authctxt.local_user = local_user; 377 authctxt.host = host; 378 authctxt.service = "ssh-connection"; /* service name */ 379 authctxt.success = 0; 380 authctxt.method = authmethod_lookup("none"); 381 authctxt.authlist = NULL; 382 authctxt.methoddata = NULL; 383 authctxt.sensitive = sensitive; 384 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 385 authctxt.info_req_seen = 0; 386 authctxt.agent_fd = -1; 387 if (authctxt.method == NULL) 388 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 389 390 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 391 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 392 (r = sshpkt_send(ssh)) != 0) 393 fatal("%s: %s", __func__, ssh_err(r)); 394 395 ssh->authctxt = &authctxt; 396 ssh_dispatch_init(ssh, &input_userauth_error); 397 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 398 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 399 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 400 ssh->authctxt = NULL; 401 402 pubkey_cleanup(&authctxt); 403 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 404 405 if (!authctxt.success) 406 fatal("Authentication failed."); 407 debug("Authentication succeeded (%s).", authctxt.method->name); 408 } 409 410 /* ARGSUSED */ 411 int 412 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 413 { 414 Authctxt *authctxt = ssh->authctxt; 415 int r; 416 417 if (ssh_packet_remaining(ssh) > 0) { 418 char *reply; 419 420 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 421 goto out; 422 debug2("service_accept: %s", reply); 423 free(reply); 424 } else { 425 debug2("buggy server: service_accept w/o service"); 426 } 427 if ((r = sshpkt_get_end(ssh)) != 0) 428 goto out; 429 debug("SSH2_MSG_SERVICE_ACCEPT received"); 430 431 /* initial userauth request */ 432 userauth_none(authctxt); 433 434 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 435 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 436 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 437 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 438 r = 0; 439 out: 440 return r; 441 } 442 443 /* ARGSUSED */ 444 int 445 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 446 { 447 return kex_input_ext_info(type, seqnr, ssh); 448 } 449 450 void 451 userauth(Authctxt *authctxt, char *authlist) 452 { 453 struct ssh *ssh = active_state; /* XXX */ 454 455 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 456 authctxt->method->cleanup(authctxt); 457 458 free(authctxt->methoddata); 459 authctxt->methoddata = NULL; 460 if (authlist == NULL) { 461 authlist = authctxt->authlist; 462 } else { 463 free(authctxt->authlist); 464 authctxt->authlist = authlist; 465 } 466 for (;;) { 467 Authmethod *method = authmethod_get(authlist); 468 if (method == NULL) 469 fatal("%s@%s: Permission denied (%s).", 470 authctxt->server_user, authctxt->host, authlist); 471 authctxt->method = method; 472 473 /* reset the per method handler */ 474 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 475 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 476 477 /* and try new method */ 478 if (method->userauth(authctxt) != 0) { 479 debug2("we sent a %s packet, wait for reply", method->name); 480 break; 481 } else { 482 debug2("we did not send a packet, disable method"); 483 method->enabled = NULL; 484 } 485 } 486 } 487 488 /* ARGSUSED */ 489 int 490 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 491 { 492 fatal("input_userauth_error: bad message during authentication: " 493 "type %d", type); 494 return 0; 495 } 496 497 /* ARGSUSED */ 498 int 499 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 500 { 501 char *msg, *lang; 502 u_int len; 503 504 debug3("%s", __func__); 505 msg = packet_get_string(&len); 506 lang = packet_get_string(NULL); 507 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 508 fmprintf(stderr, "%s", msg); 509 free(msg); 510 free(lang); 511 return 0; 512 } 513 514 /* ARGSUSED */ 515 int 516 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 517 { 518 Authctxt *authctxt = ssh->authctxt; 519 520 if (authctxt == NULL) 521 fatal("input_userauth_success: no authentication context"); 522 free(authctxt->authlist); 523 authctxt->authlist = NULL; 524 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 525 authctxt->method->cleanup(authctxt); 526 free(authctxt->methoddata); 527 authctxt->methoddata = NULL; 528 authctxt->success = 1; /* break out */ 529 return 0; 530 } 531 532 int 533 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 534 { 535 Authctxt *authctxt = ssh->authctxt; 536 537 if (authctxt == NULL) 538 fatal("%s: no authentication context", __func__); 539 540 fatal("Unexpected authentication success during %s.", 541 authctxt->method->name); 542 return 0; 543 } 544 545 /* ARGSUSED */ 546 int 547 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 548 { 549 Authctxt *authctxt = ssh->authctxt; 550 char *authlist = NULL; 551 u_char partial; 552 int r; 553 554 if (authctxt == NULL) 555 fatal("input_userauth_failure: no authentication context"); 556 557 if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 || 558 (r = sshpkt_get_u8(ssh, &partial)) != 0 || 559 (r = sshpkt_get_end(ssh)) != 0) 560 goto out; 561 562 if (partial != 0) { 563 verbose("Authenticated with partial success."); 564 /* reset state */ 565 pubkey_reset(authctxt); 566 } 567 debug("Authentications that can continue: %s", authlist); 568 569 userauth(authctxt, authlist); 570 authlist = NULL; 571 out: 572 free(authlist); 573 return 0; 574 } 575 576 /* 577 * Format an identity for logging including filename, key type, fingerprint 578 * and location (agent, etc.). Caller must free. 579 */ 580 static char * 581 format_identity(Identity *id) 582 { 583 char *fp = NULL, *ret = NULL; 584 585 if (id->key != NULL) { 586 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 587 SSH_FP_DEFAULT); 588 } 589 xasprintf(&ret, "%s %s%s%s%s%s%s", 590 id->filename, 591 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 592 fp ? fp : "", 593 id->userprovided ? " explicit" : "", 594 (id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "", 595 id->agent_fd != -1 ? " agent" : ""); 596 free(fp); 597 return ret; 598 } 599 600 /* ARGSUSED */ 601 int 602 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 603 { 604 Authctxt *authctxt = ssh->authctxt; 605 struct sshkey *key = NULL; 606 Identity *id = NULL; 607 int pktype, found = 0, sent = 0; 608 size_t blen; 609 char *pkalg = NULL, *fp = NULL, *ident = NULL; 610 u_char *pkblob = NULL; 611 int r; 612 613 if (authctxt == NULL) 614 fatal("input_userauth_pk_ok: no authentication context"); 615 616 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 617 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 618 (r = sshpkt_get_end(ssh)) != 0) 619 goto done; 620 621 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 622 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 623 goto done; 624 } 625 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 626 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 627 goto done; 628 } 629 if (key->type != pktype) { 630 error("input_userauth_pk_ok: type mismatch " 631 "for decoded key (received %d, expected %d)", 632 key->type, pktype); 633 goto done; 634 } 635 636 /* 637 * search keys in the reverse order, because last candidate has been 638 * moved to the end of the queue. this also avoids confusion by 639 * duplicate keys 640 */ 641 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 642 if (sshkey_equal(key, id->key)) { 643 found = 1; 644 break; 645 } 646 } 647 if (!found || id == NULL) { 648 fp = sshkey_fingerprint(key, options.fingerprint_hash, 649 SSH_FP_DEFAULT); 650 error("%s: server replied with unknown key: %s %s", __func__, 651 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 652 goto done; 653 } 654 ident = format_identity(id); 655 debug("Server accepts key: %s", ident); 656 sent = sign_and_send_pubkey(ssh, authctxt, id); 657 r = 0; 658 done: 659 sshkey_free(key); 660 free(ident); 661 free(fp); 662 free(pkalg); 663 free(pkblob); 664 665 /* try another method if we did not send a packet */ 666 if (r == 0 && sent == 0) 667 userauth(authctxt, NULL); 668 return r; 669 } 670 671 #ifdef GSSAPI 672 int 673 userauth_gssapi(Authctxt *authctxt) 674 { 675 struct ssh *ssh = active_state; /* XXX */ 676 Gssctxt *gssctxt = NULL; 677 static gss_OID_set gss_supported = NULL; 678 static u_int mech = 0; 679 OM_uint32 min; 680 int r, ok = 0; 681 682 /* Try one GSSAPI method at a time, rather than sending them all at 683 * once. */ 684 685 if (gss_supported == NULL) 686 gss_indicate_mechs(&min, &gss_supported); 687 688 /* Check to see if the mechanism is usable before we offer it */ 689 while (mech < gss_supported->count && !ok) { 690 /* My DER encoding requires length<128 */ 691 if (gss_supported->elements[mech].length < 128 && 692 ssh_gssapi_check_mechanism(&gssctxt, 693 &gss_supported->elements[mech], authctxt->host)) { 694 ok = 1; /* Mechanism works */ 695 } else { 696 mech++; 697 } 698 } 699 700 if (!ok) 701 return 0; 702 703 authctxt->methoddata=(void *)gssctxt; 704 705 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 706 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 707 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 708 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 709 (r = sshpkt_put_u32(ssh, 1)) != 0 || 710 (r = sshpkt_put_u32(ssh, 711 (gss_supported->elements[mech].length) + 2)) != 0 || 712 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 713 (r = sshpkt_put_u8(ssh, 714 gss_supported->elements[mech].length)) != 0 || 715 (r = sshpkt_put(ssh, 716 gss_supported->elements[mech].elements, 717 gss_supported->elements[mech].length)) != 0 || 718 (r = sshpkt_send(ssh)) != 0) 719 fatal("%s: %s", __func__, ssh_err(r)); 720 721 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 722 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 723 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 724 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 725 726 mech++; /* Move along to next candidate */ 727 728 return 1; 729 } 730 731 static OM_uint32 732 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 733 { 734 Authctxt *authctxt = ssh->authctxt; 735 Gssctxt *gssctxt = authctxt->methoddata; 736 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 737 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 738 gss_buffer_desc gssbuf; 739 OM_uint32 status, ms, flags; 740 int r; 741 742 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 743 recv_tok, &send_tok, &flags); 744 745 if (send_tok.length > 0) { 746 u_char type = GSS_ERROR(status) ? 747 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 748 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 749 750 if ((r = sshpkt_start(ssh, type)) != 0 || 751 (r = sshpkt_put_string(ssh, send_tok.value, 752 send_tok.length)) != 0 || 753 (r = sshpkt_send(ssh)) != 0) 754 fatal("%s: %s", __func__, ssh_err(r)); 755 756 gss_release_buffer(&ms, &send_tok); 757 } 758 759 if (status == GSS_S_COMPLETE) { 760 /* send either complete or MIC, depending on mechanism */ 761 if (!(flags & GSS_C_INTEG_FLAG)) { 762 if ((r = sshpkt_start(ssh, 763 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 764 (r = sshpkt_send(ssh)) != 0) 765 fatal("%s: %s", __func__, ssh_err(r)); 766 } else { 767 struct sshbuf *b; 768 769 if ((b = sshbuf_new()) == NULL) 770 fatal("%s: sshbuf_new failed", __func__); 771 ssh_gssapi_buildmic(b, authctxt->server_user, 772 authctxt->service, "gssapi-with-mic"); 773 774 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 775 fatal("%s: sshbuf_mutable_ptr failed", __func__); 776 gssbuf.length = sshbuf_len(b); 777 778 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 779 780 if (!GSS_ERROR(status)) { 781 if ((r = sshpkt_start(ssh, 782 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 783 (r = sshpkt_put_string(ssh, mic.value, 784 mic.length)) != 0 || 785 (r = sshpkt_send(ssh)) != 0) 786 fatal("%s: %s", __func__, ssh_err(r)); 787 } 788 789 sshbuf_free(b); 790 gss_release_buffer(&ms, &mic); 791 } 792 } 793 794 return status; 795 } 796 797 /* ARGSUSED */ 798 int 799 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 800 { 801 Authctxt *authctxt = ssh->authctxt; 802 Gssctxt *gssctxt; 803 size_t oidlen; 804 u_char *oidv = NULL; 805 int r; 806 807 if (authctxt == NULL) 808 fatal("input_gssapi_response: no authentication context"); 809 gssctxt = authctxt->methoddata; 810 811 /* Setup our OID */ 812 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 813 goto done; 814 815 if (oidlen <= 2 || 816 oidv[0] != SSH_GSS_OIDTYPE || 817 oidv[1] != oidlen - 2) { 818 debug("Badly encoded mechanism OID received"); 819 userauth(authctxt, NULL); 820 goto ok; 821 } 822 823 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 824 fatal("Server returned different OID than expected"); 825 826 if ((r = sshpkt_get_end(ssh)) != 0) 827 goto done; 828 829 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 830 /* Start again with next method on list */ 831 debug("Trying to start again"); 832 userauth(authctxt, NULL); 833 goto ok; 834 } 835 ok: 836 r = 0; 837 done: 838 free(oidv); 839 return r; 840 } 841 842 /* ARGSUSED */ 843 int 844 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 845 { 846 Authctxt *authctxt = ssh->authctxt; 847 gss_buffer_desc recv_tok; 848 u_char *p = NULL; 849 size_t len; 850 OM_uint32 status; 851 int r; 852 853 if (authctxt == NULL) 854 fatal("input_gssapi_response: no authentication context"); 855 856 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 857 (r = sshpkt_get_end(ssh)) != 0) 858 goto out; 859 860 recv_tok.value = p; 861 recv_tok.length = len; 862 status = process_gssapi_token(ssh, &recv_tok); 863 864 /* Start again with the next method in the list */ 865 if (GSS_ERROR(status)) { 866 userauth(authctxt, NULL); 867 /* ok */ 868 } 869 r = 0; 870 out: 871 free(p); 872 return r; 873 } 874 875 /* ARGSUSED */ 876 int 877 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 878 { 879 Authctxt *authctxt = ssh->authctxt; 880 Gssctxt *gssctxt; 881 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 882 gss_buffer_desc recv_tok; 883 OM_uint32 ms; 884 u_char *p = NULL; 885 size_t len; 886 int r; 887 888 if (authctxt == NULL) 889 fatal("input_gssapi_response: no authentication context"); 890 gssctxt = authctxt->methoddata; 891 892 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 893 (r = sshpkt_get_end(ssh)) != 0) { 894 free(p); 895 return r; 896 } 897 898 /* Stick it into GSSAPI and see what it says */ 899 recv_tok.value = p; 900 recv_tok.length = len; 901 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 902 &recv_tok, &send_tok, NULL); 903 free(p); 904 gss_release_buffer(&ms, &send_tok); 905 906 /* Server will be returning a failed packet after this one */ 907 return 0; 908 } 909 910 /* ARGSUSED */ 911 int 912 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 913 { 914 char *msg = NULL; 915 char *lang = NULL; 916 int r; 917 918 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 919 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 920 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 921 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 922 goto out; 923 r = sshpkt_get_end(ssh); 924 debug("Server GSSAPI Error:\n%s", msg); 925 out: 926 free(msg); 927 free(lang); 928 return r; 929 } 930 #endif /* GSSAPI */ 931 932 int 933 userauth_none(Authctxt *authctxt) 934 { 935 struct ssh *ssh = active_state; /* XXX */ 936 int r; 937 938 /* initial userauth request */ 939 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 940 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 941 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 942 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 943 (r = sshpkt_send(ssh)) != 0) 944 fatal("%s: %s", __func__, ssh_err(r)); 945 return 1; 946 } 947 948 int 949 userauth_passwd(Authctxt *authctxt) 950 { 951 struct ssh *ssh = active_state; /* XXX */ 952 static int attempt = 0; 953 char prompt[256]; 954 char *password; 955 const char *host = options.host_key_alias ? options.host_key_alias : 956 authctxt->host; 957 int r; 958 959 if (attempt++ >= options.number_of_password_prompts) 960 return 0; 961 962 if (attempt != 1) 963 error("Permission denied, please try again."); 964 965 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 966 authctxt->server_user, host); 967 password = read_passphrase(prompt, 0); 968 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 969 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 970 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 971 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 972 (r = sshpkt_put_u8(ssh, 0)) != 0 || 973 (r = sshpkt_put_cstring(ssh, password)) != 0 || 974 (r = sshpkt_add_padding(ssh, 64)) != 0 || 975 (r = sshpkt_send(ssh)) != 0) 976 fatal("%s: %s", __func__, ssh_err(r)); 977 978 if (password) 979 freezero(password, strlen(password)); 980 981 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 982 &input_userauth_passwd_changereq); 983 984 return 1; 985 } 986 987 /* 988 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 989 */ 990 /* ARGSUSED */ 991 int 992 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 993 { 994 Authctxt *authctxt = ssh->authctxt; 995 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 996 char prompt[256]; 997 const char *host; 998 int r; 999 1000 debug2("input_userauth_passwd_changereq"); 1001 1002 if (authctxt == NULL) 1003 fatal("input_userauth_passwd_changereq: " 1004 "no authentication context"); 1005 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1006 1007 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1008 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1009 goto out; 1010 if (strlen(info) > 0) 1011 logit("%s", info); 1012 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1013 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1014 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1015 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1016 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1017 goto out; 1018 1019 snprintf(prompt, sizeof(prompt), 1020 "Enter %.30s@%.128s's old password: ", 1021 authctxt->server_user, host); 1022 password = read_passphrase(prompt, 0); 1023 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1024 goto out; 1025 1026 freezero(password, strlen(password)); 1027 password = NULL; 1028 while (password == NULL) { 1029 snprintf(prompt, sizeof(prompt), 1030 "Enter %.30s@%.128s's new password: ", 1031 authctxt->server_user, host); 1032 password = read_passphrase(prompt, RP_ALLOW_EOF); 1033 if (password == NULL) { 1034 /* bail out */ 1035 r = 0; 1036 goto out; 1037 } 1038 snprintf(prompt, sizeof(prompt), 1039 "Retype %.30s@%.128s's new password: ", 1040 authctxt->server_user, host); 1041 retype = read_passphrase(prompt, 0); 1042 if (strcmp(password, retype) != 0) { 1043 freezero(password, strlen(password)); 1044 logit("Mismatch; try again, EOF to quit."); 1045 password = NULL; 1046 } 1047 freezero(retype, strlen(retype)); 1048 } 1049 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1050 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1051 (r = sshpkt_send(ssh)) != 0) 1052 goto out; 1053 1054 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1055 &input_userauth_passwd_changereq); 1056 r = 0; 1057 out: 1058 if (password) 1059 freezero(password, strlen(password)); 1060 free(info); 1061 free(lang); 1062 return r; 1063 } 1064 1065 /* 1066 * Select an algorithm for publickey signatures. 1067 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1068 * 1069 * Call with ssh==NULL to ignore server-sig-algs extension list and 1070 * only attempt with the key's base signature type. 1071 */ 1072 static char * 1073 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1074 { 1075 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1076 1077 /* 1078 * The signature algorithm will only differ from the key algorithm 1079 * for RSA keys/certs and when the server advertises support for 1080 * newer (SHA2) algorithms. 1081 */ 1082 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1083 (key->type != KEY_RSA && key->type != KEY_RSA_CERT)) { 1084 /* Filter base key signature alg against our configuration */ 1085 return match_list(sshkey_ssh_name(key), 1086 options.pubkey_key_types, NULL); 1087 } 1088 1089 /* 1090 * For RSA keys/certs, since these might have a different sig type: 1091 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1092 * that also appears in the supported signature algorithms list from 1093 * the server. 1094 */ 1095 oallowed = allowed = xstrdup(options.pubkey_key_types); 1096 while ((cp = strsep(&allowed, ",")) != NULL) { 1097 if (sshkey_type_from_name(cp) != key->type) 1098 continue; 1099 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1100 if (tmp != NULL) 1101 alg = xstrdup(cp); 1102 free(tmp); 1103 if (alg != NULL) 1104 break; 1105 } 1106 free(oallowed); 1107 return alg; 1108 } 1109 1110 static int 1111 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1112 const u_char *data, size_t datalen, u_int compat, const char *alg) 1113 { 1114 struct sshkey *prv; 1115 int r; 1116 1117 /* The agent supports this key. */ 1118 if (id->key != NULL && id->agent_fd != -1) { 1119 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1120 data, datalen, alg, compat); 1121 } 1122 1123 /* 1124 * We have already loaded the private key or the private key is 1125 * stored in external hardware. 1126 */ 1127 if (id->key != NULL && 1128 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1129 if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen, 1130 alg, compat)) != 0) 1131 return r; 1132 /* 1133 * PKCS#11 tokens may not support all signature algorithms, 1134 * so check what we get back. 1135 */ 1136 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) 1137 return r; 1138 return 0; 1139 } 1140 1141 /* Load the private key from the file. */ 1142 if ((prv = load_identity_file(id)) == NULL) 1143 return SSH_ERR_KEY_NOT_FOUND; 1144 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1145 error("%s: private key %s contents do not match public", 1146 __func__, id->filename); 1147 return SSH_ERR_KEY_NOT_FOUND; 1148 } 1149 r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1150 sshkey_free(prv); 1151 return r; 1152 } 1153 1154 static int 1155 id_filename_matches(Identity *id, Identity *private_id) 1156 { 1157 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1158 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1159 size_t i, slen; 1160 1161 if (strcmp(id->filename, private_id->filename) == 0) 1162 return 1; 1163 for (i = 0; suffixes[i]; i++) { 1164 slen = strlen(suffixes[i]); 1165 if (len > slen && plen == len - slen && 1166 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1167 memcmp(id->filename, private_id->filename, plen) == 0) 1168 return 1; 1169 } 1170 return 0; 1171 } 1172 1173 static int 1174 sign_and_send_pubkey(struct ssh *ssh, Authctxt *authctxt, Identity *id) 1175 { 1176 struct sshbuf *b = NULL; 1177 Identity *private_id, *sign_id = NULL; 1178 u_char *signature = NULL; 1179 size_t slen = 0, skip = 0; 1180 int r, fallback_sigtype, sent = 0; 1181 char *alg = NULL, *fp = NULL; 1182 const char *loc = ""; 1183 1184 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1185 SSH_FP_DEFAULT)) == NULL) 1186 return 0; 1187 1188 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1189 1190 /* 1191 * If the key is an certificate, try to find a matching private key 1192 * and use it to complete the signature. 1193 * If no such private key exists, fall back to trying the certificate 1194 * key itself in case it has a private half already loaded. 1195 * This will try to set sign_id to the private key that will perform 1196 * the signature. 1197 */ 1198 if (sshkey_is_cert(id->key)) { 1199 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1200 if (sshkey_equal_public(id->key, private_id->key) && 1201 id->key->type != private_id->key->type) { 1202 sign_id = private_id; 1203 break; 1204 } 1205 } 1206 /* 1207 * Exact key matches are preferred, but also allow 1208 * filename matches for non-PKCS#11/agent keys that 1209 * didn't load public keys. This supports the case 1210 * of keeping just a private key file and public 1211 * certificate on disk. 1212 */ 1213 if (sign_id == NULL && 1214 !id->isprivate && id->agent_fd == -1 && 1215 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1216 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1217 if (private_id->key == NULL && 1218 id_filename_matches(id, private_id)) { 1219 sign_id = private_id; 1220 break; 1221 } 1222 } 1223 } 1224 if (sign_id != NULL) { 1225 debug2("%s: using private key \"%s\"%s for " 1226 "certificate", __func__, id->filename, 1227 id->agent_fd != -1 ? " from agent" : ""); 1228 } else { 1229 debug("%s: no separate private key for certificate " 1230 "\"%s\"", __func__, id->filename); 1231 } 1232 } 1233 1234 /* 1235 * If the above didn't select another identity to do the signing 1236 * then default to the one we started with. 1237 */ 1238 if (sign_id == NULL) 1239 sign_id = id; 1240 1241 /* assemble and sign data */ 1242 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1243 free(alg); 1244 slen = 0; 1245 signature = NULL; 1246 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1247 id->key)) == NULL) { 1248 error("%s: no mutual signature supported", __func__); 1249 goto out; 1250 } 1251 debug3("%s: signing using %s", __func__, alg); 1252 1253 sshbuf_free(b); 1254 if ((b = sshbuf_new()) == NULL) 1255 fatal("%s: sshbuf_new failed", __func__); 1256 if (datafellows & SSH_OLD_SESSIONID) { 1257 if ((r = sshbuf_put(b, session_id2, 1258 session_id2_len)) != 0) { 1259 fatal("%s: sshbuf_put: %s", 1260 __func__, ssh_err(r)); 1261 } 1262 } else { 1263 if ((r = sshbuf_put_string(b, session_id2, 1264 session_id2_len)) != 0) { 1265 fatal("%s: sshbuf_put_string: %s", 1266 __func__, ssh_err(r)); 1267 } 1268 } 1269 skip = sshbuf_len(b); 1270 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1271 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1272 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1273 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1274 (r = sshbuf_put_u8(b, 1)) != 0 || 1275 (r = sshbuf_put_cstring(b, alg)) != 0 || 1276 (r = sshkey_puts(id->key, b)) != 0) { 1277 fatal("%s: assemble signed data: %s", 1278 __func__, ssh_err(r)); 1279 } 1280 1281 /* generate signature */ 1282 r = identity_sign(sign_id, &signature, &slen, 1283 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1284 if (r == 0) 1285 break; 1286 else if (r == SSH_ERR_KEY_NOT_FOUND) 1287 goto out; /* soft failure */ 1288 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1289 !fallback_sigtype) { 1290 if (sign_id->agent_fd != -1) 1291 loc = "agent "; 1292 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1293 loc = "token "; 1294 logit("%skey %s %s returned incorrect signature type", 1295 loc, sshkey_type(id->key), fp); 1296 continue; 1297 } 1298 error("%s: signing failed: %s", __func__, ssh_err(r)); 1299 goto out; 1300 } 1301 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1302 fatal("%s: no signature", __func__); 1303 1304 /* append signature */ 1305 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1306 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1307 1308 #ifdef DEBUG_PK 1309 sshbuf_dump(b, stderr); 1310 #endif 1311 /* skip session id and packet type */ 1312 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1313 fatal("%s: consume: %s", __func__, ssh_err(r)); 1314 1315 /* put remaining data from buffer into packet */ 1316 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1317 (r = sshpkt_putb(ssh, b)) != 0 || 1318 (r = sshpkt_send(ssh)) != 0) 1319 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1320 1321 /* success */ 1322 sent = 1; 1323 1324 out: 1325 free(fp); 1326 free(alg); 1327 sshbuf_free(b); 1328 freezero(signature, slen); 1329 return sent; 1330 } 1331 1332 static int 1333 send_pubkey_test(struct ssh *ssh, Authctxt *authctxt, Identity *id) 1334 { 1335 u_char *blob = NULL; 1336 char *alg = NULL; 1337 size_t bloblen; 1338 u_int have_sig = 0; 1339 int sent = 0, r; 1340 1341 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1342 debug("%s: no mutual signature algorithm", __func__); 1343 goto out; 1344 } 1345 1346 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1347 /* we cannot handle this key */ 1348 debug3("%s: cannot handle key", __func__); 1349 goto out; 1350 } 1351 /* register callback for USERAUTH_PK_OK message */ 1352 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1353 1354 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1355 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1356 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1357 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1358 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1359 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1360 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1361 (r = sshpkt_send(ssh)) != 0) 1362 fatal("%s: %s", __func__, ssh_err(r)); 1363 sent = 1; 1364 1365 out: 1366 free(alg); 1367 free(blob); 1368 return sent; 1369 } 1370 1371 static struct sshkey * 1372 load_identity_file(Identity *id) 1373 { 1374 struct sshkey *private = NULL; 1375 char prompt[300], *passphrase, *comment; 1376 int r, perm_ok = 0, quit = 0, i; 1377 struct stat st; 1378 1379 if (stat(id->filename, &st) < 0) { 1380 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1381 id->filename, strerror(errno)); 1382 return NULL; 1383 } 1384 snprintf(prompt, sizeof prompt, 1385 "Enter passphrase for key '%.100s': ", id->filename); 1386 for (i = 0; i <= options.number_of_password_prompts; i++) { 1387 if (i == 0) 1388 passphrase = ""; 1389 else { 1390 passphrase = read_passphrase(prompt, 0); 1391 if (*passphrase == '\0') { 1392 debug2("no passphrase given, try next key"); 1393 free(passphrase); 1394 break; 1395 } 1396 } 1397 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1398 passphrase, &private, &comment, &perm_ok))) { 1399 case 0: 1400 break; 1401 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1402 if (options.batch_mode) { 1403 quit = 1; 1404 break; 1405 } 1406 if (i != 0) 1407 debug2("bad passphrase given, try again..."); 1408 break; 1409 case SSH_ERR_SYSTEM_ERROR: 1410 if (errno == ENOENT) { 1411 debug2("Load key \"%s\": %s", 1412 id->filename, ssh_err(r)); 1413 quit = 1; 1414 break; 1415 } 1416 /* FALLTHROUGH */ 1417 default: 1418 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1419 quit = 1; 1420 break; 1421 } 1422 if (!quit && private != NULL && id->agent_fd == -1 && 1423 !(id->key && id->isprivate)) 1424 maybe_add_key_to_agent(id->filename, private, comment, 1425 passphrase); 1426 if (i > 0) 1427 freezero(passphrase, strlen(passphrase)); 1428 free(comment); 1429 if (private != NULL || quit) 1430 break; 1431 } 1432 return private; 1433 } 1434 1435 static int 1436 key_type_allowed_by_config(struct sshkey *key) 1437 { 1438 if (match_pattern_list(sshkey_ssh_name(key), 1439 options.pubkey_key_types, 0) == 1) 1440 return 1; 1441 1442 /* RSA keys/certs might be allowed by alternate signature types */ 1443 switch (key->type) { 1444 case KEY_RSA: 1445 if (match_pattern_list("rsa-sha2-512", 1446 options.pubkey_key_types, 0) == 1) 1447 return 1; 1448 if (match_pattern_list("rsa-sha2-256", 1449 options.pubkey_key_types, 0) == 1) 1450 return 1; 1451 break; 1452 case KEY_RSA_CERT: 1453 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1454 options.pubkey_key_types, 0) == 1) 1455 return 1; 1456 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1457 options.pubkey_key_types, 0) == 1) 1458 return 1; 1459 break; 1460 } 1461 return 0; 1462 } 1463 1464 1465 /* 1466 * try keys in the following order: 1467 * 1. certificates listed in the config file 1468 * 2. other input certificates 1469 * 3. agent keys that are found in the config file 1470 * 4. other agent keys 1471 * 5. keys that are only listed in the config file 1472 */ 1473 static void 1474 pubkey_prepare(Authctxt *authctxt) 1475 { 1476 struct identity *id, *id2, *tmp; 1477 struct idlist agent, files, *preferred; 1478 struct sshkey *key; 1479 int agent_fd = -1, i, r, found; 1480 size_t j; 1481 struct ssh_identitylist *idlist; 1482 char *ident; 1483 1484 TAILQ_INIT(&agent); /* keys from the agent */ 1485 TAILQ_INIT(&files); /* keys from the config file */ 1486 preferred = &authctxt->keys; 1487 TAILQ_INIT(preferred); /* preferred order of keys */ 1488 1489 /* list of keys stored in the filesystem and PKCS#11 */ 1490 for (i = 0; i < options.num_identity_files; i++) { 1491 key = options.identity_keys[i]; 1492 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1493 continue; 1494 options.identity_keys[i] = NULL; 1495 id = xcalloc(1, sizeof(*id)); 1496 id->agent_fd = -1; 1497 id->key = key; 1498 id->filename = xstrdup(options.identity_files[i]); 1499 id->userprovided = options.identity_file_userprovided[i]; 1500 TAILQ_INSERT_TAIL(&files, id, next); 1501 } 1502 /* list of certificates specified by user */ 1503 for (i = 0; i < options.num_certificate_files; i++) { 1504 key = options.certificates[i]; 1505 if (!sshkey_is_cert(key) || key->cert == NULL || 1506 key->cert->type != SSH2_CERT_TYPE_USER) 1507 continue; 1508 id = xcalloc(1, sizeof(*id)); 1509 id->agent_fd = -1; 1510 id->key = key; 1511 id->filename = xstrdup(options.certificate_files[i]); 1512 id->userprovided = options.certificate_file_userprovided[i]; 1513 TAILQ_INSERT_TAIL(preferred, id, next); 1514 } 1515 /* list of keys supported by the agent */ 1516 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1517 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1518 debug("%s: ssh_get_authentication_socket: %s", 1519 __func__, ssh_err(r)); 1520 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1521 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1522 debug("%s: ssh_fetch_identitylist: %s", 1523 __func__, ssh_err(r)); 1524 close(agent_fd); 1525 } else { 1526 for (j = 0; j < idlist->nkeys; j++) { 1527 found = 0; 1528 TAILQ_FOREACH(id, &files, next) { 1529 /* 1530 * agent keys from the config file are 1531 * preferred 1532 */ 1533 if (sshkey_equal(idlist->keys[j], id->key)) { 1534 TAILQ_REMOVE(&files, id, next); 1535 TAILQ_INSERT_TAIL(preferred, id, next); 1536 id->agent_fd = agent_fd; 1537 found = 1; 1538 break; 1539 } 1540 } 1541 if (!found && !options.identities_only) { 1542 id = xcalloc(1, sizeof(*id)); 1543 /* XXX "steals" key/comment from idlist */ 1544 id->key = idlist->keys[j]; 1545 id->filename = idlist->comments[j]; 1546 idlist->keys[j] = NULL; 1547 idlist->comments[j] = NULL; 1548 id->agent_fd = agent_fd; 1549 TAILQ_INSERT_TAIL(&agent, id, next); 1550 } 1551 } 1552 ssh_free_identitylist(idlist); 1553 /* append remaining agent keys */ 1554 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1555 TAILQ_REMOVE(&agent, id, next); 1556 TAILQ_INSERT_TAIL(preferred, id, next); 1557 } 1558 authctxt->agent_fd = agent_fd; 1559 } 1560 /* Prefer PKCS11 keys that are explicitly listed */ 1561 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1562 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1563 continue; 1564 found = 0; 1565 TAILQ_FOREACH(id2, &files, next) { 1566 if (id2->key == NULL || 1567 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1568 continue; 1569 if (sshkey_equal(id->key, id2->key)) { 1570 TAILQ_REMOVE(&files, id, next); 1571 TAILQ_INSERT_TAIL(preferred, id, next); 1572 found = 1; 1573 break; 1574 } 1575 } 1576 /* If IdentitiesOnly set and key not found then don't use it */ 1577 if (!found && options.identities_only) { 1578 TAILQ_REMOVE(&files, id, next); 1579 freezero(id, sizeof(*id)); 1580 } 1581 } 1582 /* append remaining keys from the config file */ 1583 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1584 TAILQ_REMOVE(&files, id, next); 1585 TAILQ_INSERT_TAIL(preferred, id, next); 1586 } 1587 /* finally, filter by PubkeyAcceptedKeyTypes */ 1588 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1589 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1590 debug("Skipping %s key %s - " 1591 "not in PubkeyAcceptedKeyTypes", 1592 sshkey_ssh_name(id->key), id->filename); 1593 TAILQ_REMOVE(preferred, id, next); 1594 sshkey_free(id->key); 1595 free(id->filename); 1596 memset(id, 0, sizeof(*id)); 1597 continue; 1598 } 1599 } 1600 /* List the keys we plan on using */ 1601 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1602 ident = format_identity(id); 1603 debug("Will attempt key: %s", ident); 1604 free(ident); 1605 } 1606 debug2("%s: done", __func__); 1607 } 1608 1609 static void 1610 pubkey_cleanup(Authctxt *authctxt) 1611 { 1612 Identity *id; 1613 1614 if (authctxt->agent_fd != -1) 1615 ssh_close_authentication_socket(authctxt->agent_fd); 1616 for (id = TAILQ_FIRST(&authctxt->keys); id; 1617 id = TAILQ_FIRST(&authctxt->keys)) { 1618 TAILQ_REMOVE(&authctxt->keys, id, next); 1619 sshkey_free(id->key); 1620 free(id->filename); 1621 free(id); 1622 } 1623 } 1624 1625 static void 1626 pubkey_reset(Authctxt *authctxt) 1627 { 1628 Identity *id; 1629 1630 TAILQ_FOREACH(id, &authctxt->keys, next) 1631 id->tried = 0; 1632 } 1633 1634 static int 1635 try_identity(Identity *id) 1636 { 1637 if (!id->key) 1638 return (0); 1639 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1640 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1641 debug("Skipped %s key %s for RSA/MD5 server", 1642 sshkey_type(id->key), id->filename); 1643 return (0); 1644 } 1645 return 1; 1646 } 1647 1648 int 1649 userauth_pubkey(Authctxt *authctxt) 1650 { 1651 struct ssh *ssh = active_state; /* XXX */ 1652 Identity *id; 1653 int sent = 0; 1654 char *ident; 1655 1656 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1657 if (id->tried++) 1658 return (0); 1659 /* move key to the end of the queue */ 1660 TAILQ_REMOVE(&authctxt->keys, id, next); 1661 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1662 /* 1663 * send a test message if we have the public key. for 1664 * encrypted keys we cannot do this and have to load the 1665 * private key instead 1666 */ 1667 if (id->key != NULL) { 1668 if (try_identity(id)) { 1669 ident = format_identity(id); 1670 debug("Offering public key: %s", ident); 1671 free(ident); 1672 sent = send_pubkey_test(ssh, authctxt, id); 1673 } 1674 } else { 1675 debug("Trying private key: %s", id->filename); 1676 id->key = load_identity_file(id); 1677 if (id->key != NULL) { 1678 if (try_identity(id)) { 1679 id->isprivate = 1; 1680 sent = sign_and_send_pubkey(ssh, 1681 authctxt, id); 1682 } 1683 sshkey_free(id->key); 1684 id->key = NULL; 1685 id->isprivate = 0; 1686 } 1687 } 1688 if (sent) 1689 return (sent); 1690 } 1691 return (0); 1692 } 1693 1694 /* 1695 * Send userauth request message specifying keyboard-interactive method. 1696 */ 1697 int 1698 userauth_kbdint(Authctxt *authctxt) 1699 { 1700 struct ssh *ssh = active_state; /* XXX */ 1701 static int attempt = 0; 1702 int r; 1703 1704 if (attempt++ >= options.number_of_password_prompts) 1705 return 0; 1706 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1707 if (attempt > 1 && !authctxt->info_req_seen) { 1708 debug3("userauth_kbdint: disable: no info_req_seen"); 1709 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1710 return 0; 1711 } 1712 1713 debug2("userauth_kbdint"); 1714 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1715 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1716 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1717 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1718 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1719 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1720 options.kbd_interactive_devices : "")) != 0 || 1721 (r = sshpkt_send(ssh)) != 0) 1722 fatal("%s: %s", __func__, ssh_err(r)); 1723 1724 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1725 return 1; 1726 } 1727 1728 /* 1729 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1730 */ 1731 int 1732 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1733 { 1734 Authctxt *authctxt = ssh->authctxt; 1735 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1736 char *response = NULL; 1737 u_char echo = 0; 1738 u_int num_prompts, i; 1739 int r; 1740 1741 debug2("input_userauth_info_req"); 1742 1743 if (authctxt == NULL) 1744 fatal("input_userauth_info_req: no authentication context"); 1745 1746 authctxt->info_req_seen = 1; 1747 1748 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1749 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1750 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1751 goto out; 1752 if (strlen(name) > 0) 1753 logit("%s", name); 1754 if (strlen(inst) > 0) 1755 logit("%s", inst); 1756 1757 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1758 goto out; 1759 /* 1760 * Begin to build info response packet based on prompts requested. 1761 * We commit to providing the correct number of responses, so if 1762 * further on we run into a problem that prevents this, we have to 1763 * be sure and clean this up and send a correct error response. 1764 */ 1765 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1766 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1767 goto out; 1768 1769 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1770 for (i = 0; i < num_prompts; i++) { 1771 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1772 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1773 goto out; 1774 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1775 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1776 goto out; 1777 freezero(response, strlen(response)); 1778 free(prompt); 1779 response = prompt = NULL; 1780 } 1781 /* done with parsing incoming message. */ 1782 if ((r = sshpkt_get_end(ssh)) != 0 || 1783 (r = sshpkt_add_padding(ssh, 64)) != 0) 1784 goto out; 1785 r = sshpkt_send(ssh); 1786 out: 1787 if (response) 1788 freezero(response, strlen(response)); 1789 free(prompt); 1790 free(name); 1791 free(inst); 1792 free(lang); 1793 return r; 1794 } 1795 1796 static int 1797 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1798 const u_char *data, size_t datalen) 1799 { 1800 struct sshbuf *b; 1801 struct stat st; 1802 pid_t pid; 1803 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1804 u_char rversion = 0, version = 2; 1805 void (*osigchld)(int); 1806 1807 *sigp = NULL; 1808 *lenp = 0; 1809 1810 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1811 error("%s: not installed: %s", __func__, strerror(errno)); 1812 return -1; 1813 } 1814 if (fflush(stdout) != 0) { 1815 error("%s: fflush: %s", __func__, strerror(errno)); 1816 return -1; 1817 } 1818 if (pipe(to) < 0) { 1819 error("%s: pipe: %s", __func__, strerror(errno)); 1820 return -1; 1821 } 1822 if (pipe(from) < 0) { 1823 error("%s: pipe: %s", __func__, strerror(errno)); 1824 return -1; 1825 } 1826 if ((pid = fork()) < 0) { 1827 error("%s: fork: %s", __func__, strerror(errno)); 1828 return -1; 1829 } 1830 osigchld = signal(SIGCHLD, SIG_DFL); 1831 if (pid == 0) { 1832 /* keep the socket on exec */ 1833 fcntl(sock, F_SETFD, 0); 1834 close(from[0]); 1835 if (dup2(from[1], STDOUT_FILENO) < 0) 1836 fatal("%s: dup2: %s", __func__, strerror(errno)); 1837 close(to[1]); 1838 if (dup2(to[0], STDIN_FILENO) < 0) 1839 fatal("%s: dup2: %s", __func__, strerror(errno)); 1840 close(from[1]); 1841 close(to[0]); 1842 /* Close everything but stdio and the socket */ 1843 for (i = STDERR_FILENO + 1; i < sock; i++) 1844 close(i); 1845 closefrom(sock + 1); 1846 debug3("%s: [child] pid=%ld, exec %s", 1847 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1848 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1849 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1850 strerror(errno)); 1851 } 1852 close(from[1]); 1853 close(to[0]); 1854 1855 if ((b = sshbuf_new()) == NULL) 1856 fatal("%s: sshbuf_new failed", __func__); 1857 /* send # of sock, data to be signed */ 1858 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1859 (r = sshbuf_put_string(b, data, datalen)) != 0) 1860 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1861 if (ssh_msg_send(to[1], version, b) == -1) 1862 fatal("%s: couldn't send request", __func__); 1863 sshbuf_reset(b); 1864 r = ssh_msg_recv(from[0], b); 1865 close(from[0]); 1866 close(to[1]); 1867 if (r < 0) { 1868 error("%s: no reply", __func__); 1869 goto fail; 1870 } 1871 1872 errno = 0; 1873 while (waitpid(pid, &status, 0) < 0) { 1874 if (errno != EINTR) { 1875 error("%s: waitpid %ld: %s", 1876 __func__, (long)pid, strerror(errno)); 1877 goto fail; 1878 } 1879 } 1880 if (!WIFEXITED(status)) { 1881 error("%s: exited abnormally", __func__); 1882 goto fail; 1883 } 1884 if (WEXITSTATUS(status) != 0) { 1885 error("%s: exited with status %d", 1886 __func__, WEXITSTATUS(status)); 1887 goto fail; 1888 } 1889 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1890 error("%s: buffer error: %s", __func__, ssh_err(r)); 1891 goto fail; 1892 } 1893 if (rversion != version) { 1894 error("%s: bad version", __func__); 1895 goto fail; 1896 } 1897 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1898 error("%s: buffer error: %s", __func__, ssh_err(r)); 1899 fail: 1900 signal(SIGCHLD, osigchld); 1901 sshbuf_free(b); 1902 return -1; 1903 } 1904 signal(SIGCHLD, osigchld); 1905 sshbuf_free(b); 1906 1907 return 0; 1908 } 1909 1910 int 1911 userauth_hostbased(Authctxt *authctxt) 1912 { 1913 struct ssh *ssh = active_state; /* XXX */ 1914 struct sshkey *private = NULL; 1915 struct sshbuf *b = NULL; 1916 u_char *sig = NULL, *keyblob = NULL; 1917 char *fp = NULL, *chost = NULL, *lname = NULL; 1918 size_t siglen = 0, keylen = 0; 1919 int i, r, success = 0; 1920 1921 if (authctxt->ktypes == NULL) { 1922 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1923 authctxt->ktypes = authctxt->oktypes; 1924 } 1925 1926 /* 1927 * Work through each listed type pattern in HostbasedKeyTypes, 1928 * trying each hostkey that matches the type in turn. 1929 */ 1930 for (;;) { 1931 if (authctxt->active_ktype == NULL) 1932 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1933 if (authctxt->active_ktype == NULL || 1934 *authctxt->active_ktype == '\0') 1935 break; 1936 debug3("%s: trying key type %s", __func__, 1937 authctxt->active_ktype); 1938 1939 /* check for a useful key */ 1940 private = NULL; 1941 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1942 if (authctxt->sensitive->keys[i] == NULL || 1943 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1944 continue; 1945 if (match_pattern_list( 1946 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1947 authctxt->active_ktype, 0) != 1) 1948 continue; 1949 /* we take and free the key */ 1950 private = authctxt->sensitive->keys[i]; 1951 authctxt->sensitive->keys[i] = NULL; 1952 break; 1953 } 1954 /* Found one */ 1955 if (private != NULL) 1956 break; 1957 /* No more keys of this type; advance */ 1958 authctxt->active_ktype = NULL; 1959 } 1960 if (private == NULL) { 1961 free(authctxt->oktypes); 1962 authctxt->oktypes = authctxt->ktypes = NULL; 1963 authctxt->active_ktype = NULL; 1964 debug("No more client hostkeys for hostbased authentication."); 1965 goto out; 1966 } 1967 1968 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1969 SSH_FP_DEFAULT)) == NULL) { 1970 error("%s: sshkey_fingerprint failed", __func__); 1971 goto out; 1972 } 1973 debug("%s: trying hostkey %s %s", 1974 __func__, sshkey_ssh_name(private), fp); 1975 1976 /* figure out a name for the client host */ 1977 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1978 error("%s: cannot get local ipaddr/name", __func__); 1979 goto out; 1980 } 1981 1982 /* XXX sshbuf_put_stringf? */ 1983 xasprintf(&chost, "%s.", lname); 1984 debug2("%s: chost %s", __func__, chost); 1985 1986 /* construct data */ 1987 if ((b = sshbuf_new()) == NULL) { 1988 error("%s: sshbuf_new failed", __func__); 1989 goto out; 1990 } 1991 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1992 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1993 goto out; 1994 } 1995 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1996 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1997 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1998 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1999 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2000 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2001 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2002 (r = sshbuf_put_cstring(b, chost)) != 0 || 2003 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2004 error("%s: buffer error: %s", __func__, ssh_err(r)); 2005 goto out; 2006 } 2007 2008 #ifdef DEBUG_PK 2009 sshbuf_dump(b, stderr); 2010 #endif 2011 r = ssh_keysign(private, &sig, &siglen, 2012 sshbuf_ptr(b), sshbuf_len(b)); 2013 if (r != 0) { 2014 error("sign using hostkey %s %s failed", 2015 sshkey_ssh_name(private), fp); 2016 goto out; 2017 } 2018 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2019 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2020 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2021 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2022 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2023 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2024 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2025 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2026 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2027 (r = sshpkt_send(ssh)) != 0) { 2028 error("%s: packet error: %s", __func__, ssh_err(r)); 2029 goto out; 2030 } 2031 success = 1; 2032 2033 out: 2034 if (sig != NULL) 2035 freezero(sig, siglen); 2036 free(keyblob); 2037 free(lname); 2038 free(fp); 2039 free(chost); 2040 sshkey_free(private); 2041 sshbuf_free(b); 2042 2043 return success; 2044 } 2045 2046 /* find auth method */ 2047 2048 /* 2049 * given auth method name, if configurable options permit this method fill 2050 * in auth_ident field and return true, otherwise return false. 2051 */ 2052 static int 2053 authmethod_is_enabled(Authmethod *method) 2054 { 2055 if (method == NULL) 2056 return 0; 2057 /* return false if options indicate this method is disabled */ 2058 if (method->enabled == NULL || *method->enabled == 0) 2059 return 0; 2060 /* return false if batch mode is enabled but method needs interactive mode */ 2061 if (method->batch_flag != NULL && *method->batch_flag != 0) 2062 return 0; 2063 return 1; 2064 } 2065 2066 static Authmethod * 2067 authmethod_lookup(const char *name) 2068 { 2069 Authmethod *method = NULL; 2070 if (name != NULL) 2071 for (method = authmethods; method->name != NULL; method++) 2072 if (strcmp(name, method->name) == 0) 2073 return method; 2074 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2075 return NULL; 2076 } 2077 2078 /* XXX internal state */ 2079 static Authmethod *current = NULL; 2080 static char *supported = NULL; 2081 static char *preferred = NULL; 2082 2083 /* 2084 * Given the authentication method list sent by the server, return the 2085 * next method we should try. If the server initially sends a nil list, 2086 * use a built-in default list. 2087 */ 2088 static Authmethod * 2089 authmethod_get(char *authlist) 2090 { 2091 char *name = NULL; 2092 u_int next; 2093 2094 /* Use a suitable default if we're passed a nil list. */ 2095 if (authlist == NULL || strlen(authlist) == 0) 2096 authlist = options.preferred_authentications; 2097 2098 if (supported == NULL || strcmp(authlist, supported) != 0) { 2099 debug3("start over, passed a different list %s", authlist); 2100 free(supported); 2101 supported = xstrdup(authlist); 2102 preferred = options.preferred_authentications; 2103 debug3("preferred %s", preferred); 2104 current = NULL; 2105 } else if (current != NULL && authmethod_is_enabled(current)) 2106 return current; 2107 2108 for (;;) { 2109 if ((name = match_list(preferred, supported, &next)) == NULL) { 2110 debug("No more authentication methods to try."); 2111 current = NULL; 2112 return NULL; 2113 } 2114 preferred += next; 2115 debug3("authmethod_lookup %s", name); 2116 debug3("remaining preferred: %s", preferred); 2117 if ((current = authmethod_lookup(name)) != NULL && 2118 authmethod_is_enabled(current)) { 2119 debug3("authmethod_is_enabled %s", name); 2120 debug("Next authentication method: %s", name); 2121 free(name); 2122 return current; 2123 } 2124 free(name); 2125 } 2126 } 2127 2128 static char * 2129 authmethods_get(void) 2130 { 2131 Authmethod *method = NULL; 2132 struct sshbuf *b; 2133 char *list; 2134 int r; 2135 2136 if ((b = sshbuf_new()) == NULL) 2137 fatal("%s: sshbuf_new failed", __func__); 2138 for (method = authmethods; method->name != NULL; method++) { 2139 if (authmethod_is_enabled(method)) { 2140 if ((r = sshbuf_putf(b, "%s%s", 2141 sshbuf_len(b) ? "," : "", method->name)) != 0) 2142 fatal("%s: buffer error: %s", 2143 __func__, ssh_err(r)); 2144 } 2145 } 2146 if ((list = sshbuf_dup_string(b)) == NULL) 2147 fatal("%s: sshbuf_dup_string failed", __func__); 2148 sshbuf_free(b); 2149 return list; 2150 } 2151