1 /* $OpenBSD: sshconnect2.c,v 1.292 2019/01/04 03:27:50 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "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(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 153 { 154 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 155 char *s, *all_key; 156 int r; 157 158 xxx_host = host; 159 xxx_hostaddr = hostaddr; 160 161 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 162 fatal("%s: kex_names_cat", __func__); 163 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 164 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 165 compat_cipher_proposal(options.ciphers); 166 myproposal[PROPOSAL_ENC_ALGS_STOC] = 167 compat_cipher_proposal(options.ciphers); 168 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 169 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 170 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 171 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 172 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 173 if (options.hostkeyalgorithms != NULL) { 174 all_key = sshkey_alg_list(0, 0, 1, ','); 175 if (kex_assemble_names(&options.hostkeyalgorithms, 176 KEX_DEFAULT_PK_ALG, all_key) != 0) 177 fatal("%s: kex_assemble_namelist", __func__); 178 free(all_key); 179 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 180 compat_pkalg_proposal(options.hostkeyalgorithms); 181 } else { 182 /* Enforce default */ 183 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 184 /* Prefer algorithms that we already have keys for */ 185 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 186 compat_pkalg_proposal( 187 order_hostkeyalgs(host, hostaddr, port)); 188 } 189 190 if (options.rekey_limit || options.rekey_interval) 191 packet_set_rekey_limits(options.rekey_limit, 192 options.rekey_interval); 193 194 /* start key exchange */ 195 if ((r = kex_setup(ssh, myproposal)) != 0) 196 fatal("kex_setup: %s", ssh_err(r)); 197 #ifdef WITH_OPENSSL 198 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 199 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 200 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 201 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 202 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 203 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 204 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 205 ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 206 #endif 207 ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client; 208 ssh->kex->verify_host_key=&verify_host_key_callback; 209 210 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 211 212 /* remove ext-info from the KEX proposals for rekeying */ 213 myproposal[PROPOSAL_KEX_ALGS] = 214 compat_kex_proposal(options.kex_algorithms); 215 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 216 fatal("kex_prop2buf: %s", ssh_err(r)); 217 218 session_id2 = ssh->kex->session_id; 219 session_id2_len = ssh->kex->session_id_len; 220 221 #ifdef DEBUG_KEXDH 222 /* send 1st encrypted/maced/compressed message */ 223 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 224 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 225 (r = sshpkt_send(ssh)) != 0 || 226 (r = ssh_packet_write_wait(ssh)) != 0) 227 fatal("%s: %s", __func__, ssh_err(r)); 228 #endif 229 } 230 231 /* 232 * Authenticate user 233 */ 234 235 typedef struct cauthctxt Authctxt; 236 typedef struct cauthmethod Authmethod; 237 typedef struct identity Identity; 238 typedef struct idlist Idlist; 239 240 struct identity { 241 TAILQ_ENTRY(identity) next; 242 int agent_fd; /* >=0 if agent supports key */ 243 struct sshkey *key; /* public/private key */ 244 char *filename; /* comment for agent-only keys */ 245 int tried; 246 int isprivate; /* key points to the private key */ 247 int userprovided; 248 }; 249 TAILQ_HEAD(idlist, identity); 250 251 struct cauthctxt { 252 const char *server_user; 253 const char *local_user; 254 const char *host; 255 const char *service; 256 struct cauthmethod *method; 257 sig_atomic_t success; 258 char *authlist; 259 /* pubkey */ 260 struct idlist keys; 261 int agent_fd; 262 /* hostbased */ 263 Sensitive *sensitive; 264 char *oktypes, *ktypes; 265 const char *active_ktype; 266 /* kbd-interactive */ 267 int info_req_seen; 268 int attempt_kbdint; 269 /* password */ 270 int attempt_passwd; 271 /* generic */ 272 void *methoddata; 273 }; 274 275 struct cauthmethod { 276 char *name; /* string to compare against server's list */ 277 int (*userauth)(Authctxt *authctxt); 278 void (*cleanup)(Authctxt *authctxt); 279 int *enabled; /* flag in option struct that enables method */ 280 int *batch_flag; /* flag in option struct that disables method */ 281 }; 282 283 int input_userauth_service_accept(int, u_int32_t, struct ssh *); 284 int input_userauth_ext_info(int, u_int32_t, struct ssh *); 285 int input_userauth_success(int, u_int32_t, struct ssh *); 286 int input_userauth_success_unexpected(int, u_int32_t, struct ssh *); 287 int input_userauth_failure(int, u_int32_t, struct ssh *); 288 int input_userauth_banner(int, u_int32_t, struct ssh *); 289 int input_userauth_error(int, u_int32_t, struct ssh *); 290 int input_userauth_info_req(int, u_int32_t, struct ssh *); 291 int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 292 int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 293 294 int userauth_none(Authctxt *); 295 int userauth_pubkey(Authctxt *); 296 int userauth_passwd(Authctxt *); 297 int userauth_kbdint(Authctxt *); 298 int userauth_hostbased(Authctxt *); 299 300 #ifdef GSSAPI 301 int userauth_gssapi(Authctxt *authctxt); 302 int input_gssapi_response(int type, u_int32_t, struct ssh *); 303 int input_gssapi_token(int type, u_int32_t, struct ssh *); 304 int input_gssapi_hash(int type, u_int32_t, struct ssh *); 305 int input_gssapi_error(int, u_int32_t, struct ssh *); 306 int input_gssapi_errtok(int, u_int32_t, struct ssh *); 307 #endif 308 309 void userauth(Authctxt *, char *); 310 311 static int sign_and_send_pubkey(struct ssh *ssh, Authctxt *, Identity *); 312 static void pubkey_prepare(Authctxt *); 313 static void pubkey_cleanup(Authctxt *); 314 static void pubkey_reset(Authctxt *); 315 static struct sshkey *load_identity_file(Identity *); 316 317 static Authmethod *authmethod_get(char *authlist); 318 static Authmethod *authmethod_lookup(const char *name); 319 static char *authmethods_get(void); 320 321 Authmethod authmethods[] = { 322 #ifdef GSSAPI 323 {"gssapi-with-mic", 324 userauth_gssapi, 325 NULL, 326 &options.gss_authentication, 327 NULL}, 328 #endif 329 {"hostbased", 330 userauth_hostbased, 331 NULL, 332 &options.hostbased_authentication, 333 NULL}, 334 {"publickey", 335 userauth_pubkey, 336 NULL, 337 &options.pubkey_authentication, 338 NULL}, 339 {"keyboard-interactive", 340 userauth_kbdint, 341 NULL, 342 &options.kbd_interactive_authentication, 343 &options.batch_mode}, 344 {"password", 345 userauth_passwd, 346 NULL, 347 &options.password_authentication, 348 &options.batch_mode}, 349 {"none", 350 userauth_none, 351 NULL, 352 NULL, 353 NULL}, 354 {NULL, NULL, NULL, NULL, NULL} 355 }; 356 357 void 358 ssh_userauth2(struct ssh *ssh, const char *local_user, 359 const char *server_user, char *host, Sensitive *sensitive) 360 { 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 authctxt.server_user = server_user; 372 authctxt.local_user = local_user; 373 authctxt.host = host; 374 authctxt.service = "ssh-connection"; /* service name */ 375 authctxt.success = 0; 376 authctxt.method = authmethod_lookup("none"); 377 authctxt.authlist = NULL; 378 authctxt.methoddata = NULL; 379 authctxt.sensitive = sensitive; 380 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 381 authctxt.info_req_seen = 0; 382 authctxt.attempt_kbdint = 0; 383 authctxt.attempt_passwd = 0; 384 authctxt.agent_fd = -1; 385 pubkey_prepare(&authctxt); 386 if (authctxt.method == NULL) { 387 fatal("%s: internal error: cannot send userauth none request", 388 __func__); 389 } 390 391 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 392 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 393 (r = sshpkt_send(ssh)) != 0) 394 fatal("%s: %s", __func__, ssh_err(r)); 395 396 ssh->authctxt = &authctxt; 397 ssh_dispatch_init(ssh, &input_userauth_error); 398 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 399 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 400 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 401 ssh->authctxt = NULL; 402 403 pubkey_cleanup(&authctxt); 404 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 405 406 if (!authctxt.success) 407 fatal("Authentication failed."); 408 debug("Authentication succeeded (%s).", authctxt.method->name); 409 } 410 411 /* ARGSUSED */ 412 int 413 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 414 { 415 Authctxt *authctxt = ssh->authctxt; 416 int r; 417 418 if (ssh_packet_remaining(ssh) > 0) { 419 char *reply; 420 421 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 422 goto out; 423 debug2("service_accept: %s", reply); 424 free(reply); 425 } else { 426 debug2("buggy server: service_accept w/o service"); 427 } 428 if ((r = sshpkt_get_end(ssh)) != 0) 429 goto out; 430 debug("SSH2_MSG_SERVICE_ACCEPT received"); 431 432 /* initial userauth request */ 433 userauth_none(authctxt); 434 435 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 436 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 437 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 438 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 439 r = 0; 440 out: 441 return r; 442 } 443 444 /* ARGSUSED */ 445 int 446 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 447 { 448 return kex_input_ext_info(type, seqnr, ssh); 449 } 450 451 void 452 userauth(Authctxt *authctxt, char *authlist) 453 { 454 struct ssh *ssh = active_state; /* XXX */ 455 456 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 457 authctxt->method->cleanup(authctxt); 458 459 free(authctxt->methoddata); 460 authctxt->methoddata = NULL; 461 if (authlist == NULL) { 462 authlist = authctxt->authlist; 463 } else { 464 free(authctxt->authlist); 465 authctxt->authlist = authlist; 466 } 467 for (;;) { 468 Authmethod *method = authmethod_get(authlist); 469 if (method == NULL) 470 fatal("%s@%s: Permission denied (%s).", 471 authctxt->server_user, authctxt->host, authlist); 472 authctxt->method = method; 473 474 /* reset the per method handler */ 475 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 476 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 477 478 /* and try new method */ 479 if (method->userauth(authctxt) != 0) { 480 debug2("we sent a %s packet, wait for reply", method->name); 481 break; 482 } else { 483 debug2("we did not send a packet, disable method"); 484 method->enabled = NULL; 485 } 486 } 487 } 488 489 /* ARGSUSED */ 490 int 491 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 492 { 493 fatal("input_userauth_error: bad message during authentication: " 494 "type %d", type); 495 return 0; 496 } 497 498 /* ARGSUSED */ 499 int 500 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 501 { 502 char *msg, *lang; 503 u_int len; 504 505 debug3("%s", __func__); 506 msg = packet_get_string(&len); 507 lang = packet_get_string(NULL); 508 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 509 fmprintf(stderr, "%s", msg); 510 free(msg); 511 free(lang); 512 return 0; 513 } 514 515 /* ARGSUSED */ 516 int 517 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 518 { 519 Authctxt *authctxt = ssh->authctxt; 520 521 if (authctxt == NULL) 522 fatal("input_userauth_success: no authentication context"); 523 free(authctxt->authlist); 524 authctxt->authlist = NULL; 525 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 526 authctxt->method->cleanup(authctxt); 527 free(authctxt->methoddata); 528 authctxt->methoddata = NULL; 529 authctxt->success = 1; /* break out */ 530 return 0; 531 } 532 533 int 534 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 535 { 536 Authctxt *authctxt = ssh->authctxt; 537 538 if (authctxt == NULL) 539 fatal("%s: no authentication context", __func__); 540 541 fatal("Unexpected authentication success during %s.", 542 authctxt->method->name); 543 return 0; 544 } 545 546 /* ARGSUSED */ 547 int 548 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 549 { 550 Authctxt *authctxt = ssh->authctxt; 551 char *authlist = NULL; 552 u_char partial; 553 int r; 554 555 if (authctxt == NULL) 556 fatal("input_userauth_failure: no authentication context"); 557 558 if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 || 559 (r = sshpkt_get_u8(ssh, &partial)) != 0 || 560 (r = sshpkt_get_end(ssh)) != 0) 561 goto out; 562 563 if (partial != 0) { 564 verbose("Authenticated with partial success."); 565 /* reset state */ 566 pubkey_reset(authctxt); 567 } 568 debug("Authentications that can continue: %s", authlist); 569 570 userauth(authctxt, authlist); 571 authlist = NULL; 572 out: 573 free(authlist); 574 return 0; 575 } 576 577 /* 578 * Format an identity for logging including filename, key type, fingerprint 579 * and location (agent, etc.). Caller must free. 580 */ 581 static char * 582 format_identity(Identity *id) 583 { 584 char *fp = NULL, *ret = NULL; 585 586 if (id->key != NULL) { 587 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 588 SSH_FP_DEFAULT); 589 } 590 xasprintf(&ret, "%s %s%s%s%s%s%s", 591 id->filename, 592 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 593 fp ? fp : "", 594 id->userprovided ? " explicit" : "", 595 (id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "", 596 id->agent_fd != -1 ? " agent" : ""); 597 free(fp); 598 return ret; 599 } 600 601 /* ARGSUSED */ 602 int 603 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 604 { 605 Authctxt *authctxt = ssh->authctxt; 606 struct sshkey *key = NULL; 607 Identity *id = NULL; 608 int pktype, found = 0, sent = 0; 609 size_t blen; 610 char *pkalg = NULL, *fp = NULL, *ident = NULL; 611 u_char *pkblob = NULL; 612 int r; 613 614 if (authctxt == NULL) 615 fatal("input_userauth_pk_ok: no authentication context"); 616 617 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 618 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 619 (r = sshpkt_get_end(ssh)) != 0) 620 goto done; 621 622 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 623 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 624 goto done; 625 } 626 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 627 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 628 goto done; 629 } 630 if (key->type != pktype) { 631 error("input_userauth_pk_ok: type mismatch " 632 "for decoded key (received %d, expected %d)", 633 key->type, pktype); 634 goto done; 635 } 636 637 /* 638 * search keys in the reverse order, because last candidate has been 639 * moved to the end of the queue. this also avoids confusion by 640 * duplicate keys 641 */ 642 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 643 if (sshkey_equal(key, id->key)) { 644 found = 1; 645 break; 646 } 647 } 648 if (!found || id == NULL) { 649 fp = sshkey_fingerprint(key, options.fingerprint_hash, 650 SSH_FP_DEFAULT); 651 error("%s: server replied with unknown key: %s %s", __func__, 652 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 653 goto done; 654 } 655 ident = format_identity(id); 656 debug("Server accepts key: %s", ident); 657 sent = sign_and_send_pubkey(ssh, authctxt, id); 658 r = 0; 659 done: 660 sshkey_free(key); 661 free(ident); 662 free(fp); 663 free(pkalg); 664 free(pkblob); 665 666 /* try another method if we did not send a packet */ 667 if (r == 0 && sent == 0) 668 userauth(authctxt, NULL); 669 return r; 670 } 671 672 #ifdef GSSAPI 673 int 674 userauth_gssapi(Authctxt *authctxt) 675 { 676 struct ssh *ssh = active_state; /* XXX */ 677 Gssctxt *gssctxt = NULL; 678 static gss_OID_set gss_supported = NULL; 679 static u_int mech = 0; 680 OM_uint32 min; 681 int r, ok = 0; 682 683 /* Try one GSSAPI method at a time, rather than sending them all at 684 * once. */ 685 686 if (gss_supported == NULL) 687 gss_indicate_mechs(&min, &gss_supported); 688 689 /* Check to see if the mechanism is usable before we offer it */ 690 while (mech < gss_supported->count && !ok) { 691 /* My DER encoding requires length<128 */ 692 if (gss_supported->elements[mech].length < 128 && 693 ssh_gssapi_check_mechanism(&gssctxt, 694 &gss_supported->elements[mech], authctxt->host)) { 695 ok = 1; /* Mechanism works */ 696 } else { 697 mech++; 698 } 699 } 700 701 if (!ok) 702 return 0; 703 704 authctxt->methoddata=(void *)gssctxt; 705 706 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 707 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 708 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 709 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 710 (r = sshpkt_put_u32(ssh, 1)) != 0 || 711 (r = sshpkt_put_u32(ssh, 712 (gss_supported->elements[mech].length) + 2)) != 0 || 713 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 714 (r = sshpkt_put_u8(ssh, 715 gss_supported->elements[mech].length)) != 0 || 716 (r = sshpkt_put(ssh, 717 gss_supported->elements[mech].elements, 718 gss_supported->elements[mech].length)) != 0 || 719 (r = sshpkt_send(ssh)) != 0) 720 fatal("%s: %s", __func__, ssh_err(r)); 721 722 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 723 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 724 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 725 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 726 727 mech++; /* Move along to next candidate */ 728 729 return 1; 730 } 731 732 static OM_uint32 733 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 734 { 735 Authctxt *authctxt = ssh->authctxt; 736 Gssctxt *gssctxt = authctxt->methoddata; 737 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 738 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 739 gss_buffer_desc gssbuf; 740 OM_uint32 status, ms, flags; 741 int r; 742 743 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 744 recv_tok, &send_tok, &flags); 745 746 if (send_tok.length > 0) { 747 u_char type = GSS_ERROR(status) ? 748 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 749 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 750 751 if ((r = sshpkt_start(ssh, type)) != 0 || 752 (r = sshpkt_put_string(ssh, send_tok.value, 753 send_tok.length)) != 0 || 754 (r = sshpkt_send(ssh)) != 0) 755 fatal("%s: %s", __func__, ssh_err(r)); 756 757 gss_release_buffer(&ms, &send_tok); 758 } 759 760 if (status == GSS_S_COMPLETE) { 761 /* send either complete or MIC, depending on mechanism */ 762 if (!(flags & GSS_C_INTEG_FLAG)) { 763 if ((r = sshpkt_start(ssh, 764 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 765 (r = sshpkt_send(ssh)) != 0) 766 fatal("%s: %s", __func__, ssh_err(r)); 767 } else { 768 struct sshbuf *b; 769 770 if ((b = sshbuf_new()) == NULL) 771 fatal("%s: sshbuf_new failed", __func__); 772 ssh_gssapi_buildmic(b, authctxt->server_user, 773 authctxt->service, "gssapi-with-mic"); 774 775 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 776 fatal("%s: sshbuf_mutable_ptr failed", __func__); 777 gssbuf.length = sshbuf_len(b); 778 779 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 780 781 if (!GSS_ERROR(status)) { 782 if ((r = sshpkt_start(ssh, 783 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 784 (r = sshpkt_put_string(ssh, mic.value, 785 mic.length)) != 0 || 786 (r = sshpkt_send(ssh)) != 0) 787 fatal("%s: %s", __func__, ssh_err(r)); 788 } 789 790 sshbuf_free(b); 791 gss_release_buffer(&ms, &mic); 792 } 793 } 794 795 return status; 796 } 797 798 /* ARGSUSED */ 799 int 800 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 801 { 802 Authctxt *authctxt = ssh->authctxt; 803 Gssctxt *gssctxt; 804 size_t oidlen; 805 u_char *oidv = NULL; 806 int r; 807 808 if (authctxt == NULL) 809 fatal("input_gssapi_response: no authentication context"); 810 gssctxt = authctxt->methoddata; 811 812 /* Setup our OID */ 813 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 814 goto done; 815 816 if (oidlen <= 2 || 817 oidv[0] != SSH_GSS_OIDTYPE || 818 oidv[1] != oidlen - 2) { 819 debug("Badly encoded mechanism OID received"); 820 userauth(authctxt, NULL); 821 goto ok; 822 } 823 824 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 825 fatal("Server returned different OID than expected"); 826 827 if ((r = sshpkt_get_end(ssh)) != 0) 828 goto done; 829 830 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 831 /* Start again with next method on list */ 832 debug("Trying to start again"); 833 userauth(authctxt, NULL); 834 goto ok; 835 } 836 ok: 837 r = 0; 838 done: 839 free(oidv); 840 return r; 841 } 842 843 /* ARGSUSED */ 844 int 845 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 846 { 847 Authctxt *authctxt = ssh->authctxt; 848 gss_buffer_desc recv_tok; 849 u_char *p = NULL; 850 size_t len; 851 OM_uint32 status; 852 int r; 853 854 if (authctxt == NULL) 855 fatal("input_gssapi_response: no authentication context"); 856 857 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 858 (r = sshpkt_get_end(ssh)) != 0) 859 goto out; 860 861 recv_tok.value = p; 862 recv_tok.length = len; 863 status = process_gssapi_token(ssh, &recv_tok); 864 865 /* Start again with the next method in the list */ 866 if (GSS_ERROR(status)) { 867 userauth(authctxt, NULL); 868 /* ok */ 869 } 870 r = 0; 871 out: 872 free(p); 873 return r; 874 } 875 876 /* ARGSUSED */ 877 int 878 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 879 { 880 Authctxt *authctxt = ssh->authctxt; 881 Gssctxt *gssctxt; 882 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 883 gss_buffer_desc recv_tok; 884 OM_uint32 ms; 885 u_char *p = NULL; 886 size_t len; 887 int r; 888 889 if (authctxt == NULL) 890 fatal("input_gssapi_response: no authentication context"); 891 gssctxt = authctxt->methoddata; 892 893 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 894 (r = sshpkt_get_end(ssh)) != 0) { 895 free(p); 896 return r; 897 } 898 899 /* Stick it into GSSAPI and see what it says */ 900 recv_tok.value = p; 901 recv_tok.length = len; 902 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 903 &recv_tok, &send_tok, NULL); 904 free(p); 905 gss_release_buffer(&ms, &send_tok); 906 907 /* Server will be returning a failed packet after this one */ 908 return 0; 909 } 910 911 /* ARGSUSED */ 912 int 913 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 914 { 915 char *msg = NULL; 916 char *lang = NULL; 917 int r; 918 919 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 920 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 921 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 922 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 923 goto out; 924 r = sshpkt_get_end(ssh); 925 debug("Server GSSAPI Error:\n%s", msg); 926 out: 927 free(msg); 928 free(lang); 929 return r; 930 } 931 #endif /* GSSAPI */ 932 933 int 934 userauth_none(Authctxt *authctxt) 935 { 936 struct ssh *ssh = active_state; /* XXX */ 937 int r; 938 939 /* initial userauth request */ 940 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 941 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 942 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 943 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 944 (r = sshpkt_send(ssh)) != 0) 945 fatal("%s: %s", __func__, ssh_err(r)); 946 return 1; 947 } 948 949 int 950 userauth_passwd(Authctxt *authctxt) 951 { 952 struct ssh *ssh = active_state; /* XXX */ 953 char *password, *prompt = NULL; 954 const char *host = options.host_key_alias ? options.host_key_alias : 955 authctxt->host; 956 int r; 957 958 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 959 return 0; 960 961 if (authctxt->attempt_passwd != 1) 962 error("Permission denied, please try again."); 963 964 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 965 password = read_passphrase(prompt, 0); 966 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 967 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 968 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 969 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 970 (r = sshpkt_put_u8(ssh, 0)) != 0 || 971 (r = sshpkt_put_cstring(ssh, password)) != 0 || 972 (r = sshpkt_add_padding(ssh, 64)) != 0 || 973 (r = sshpkt_send(ssh)) != 0) 974 fatal("%s: %s", __func__, ssh_err(r)); 975 976 free(prompt); 977 if (password != NULL) 978 freezero(password, strlen(password)); 979 980 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 981 &input_userauth_passwd_changereq); 982 983 return 1; 984 } 985 986 /* 987 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 988 */ 989 /* ARGSUSED */ 990 int 991 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 992 { 993 Authctxt *authctxt = ssh->authctxt; 994 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 995 char prompt[256]; 996 const char *host; 997 int r; 998 999 debug2("input_userauth_passwd_changereq"); 1000 1001 if (authctxt == NULL) 1002 fatal("input_userauth_passwd_changereq: " 1003 "no authentication context"); 1004 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1005 1006 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1007 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1008 goto out; 1009 if (strlen(info) > 0) 1010 logit("%s", info); 1011 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1012 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1013 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1014 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1015 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1016 goto out; 1017 1018 snprintf(prompt, sizeof(prompt), 1019 "Enter %.30s@%.128s's old password: ", 1020 authctxt->server_user, host); 1021 password = read_passphrase(prompt, 0); 1022 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1023 goto out; 1024 1025 freezero(password, strlen(password)); 1026 password = NULL; 1027 while (password == NULL) { 1028 snprintf(prompt, sizeof(prompt), 1029 "Enter %.30s@%.128s's new password: ", 1030 authctxt->server_user, host); 1031 password = read_passphrase(prompt, RP_ALLOW_EOF); 1032 if (password == NULL) { 1033 /* bail out */ 1034 r = 0; 1035 goto out; 1036 } 1037 snprintf(prompt, sizeof(prompt), 1038 "Retype %.30s@%.128s's new password: ", 1039 authctxt->server_user, host); 1040 retype = read_passphrase(prompt, 0); 1041 if (strcmp(password, retype) != 0) { 1042 freezero(password, strlen(password)); 1043 logit("Mismatch; try again, EOF to quit."); 1044 password = NULL; 1045 } 1046 freezero(retype, strlen(retype)); 1047 } 1048 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1049 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1050 (r = sshpkt_send(ssh)) != 0) 1051 goto out; 1052 1053 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1054 &input_userauth_passwd_changereq); 1055 r = 0; 1056 out: 1057 if (password) 1058 freezero(password, strlen(password)); 1059 free(info); 1060 free(lang); 1061 return r; 1062 } 1063 1064 /* 1065 * Select an algorithm for publickey signatures. 1066 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1067 * 1068 * Call with ssh==NULL to ignore server-sig-algs extension list and 1069 * only attempt with the key's base signature type. 1070 */ 1071 static char * 1072 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1073 { 1074 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1075 1076 /* 1077 * The signature algorithm will only differ from the key algorithm 1078 * for RSA keys/certs and when the server advertises support for 1079 * newer (SHA2) algorithms. 1080 */ 1081 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1082 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1083 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 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 authctxt->agent_fd = -1; 1617 } 1618 for (id = TAILQ_FIRST(&authctxt->keys); id; 1619 id = TAILQ_FIRST(&authctxt->keys)) { 1620 TAILQ_REMOVE(&authctxt->keys, id, next); 1621 sshkey_free(id->key); 1622 free(id->filename); 1623 free(id); 1624 } 1625 } 1626 1627 static void 1628 pubkey_reset(Authctxt *authctxt) 1629 { 1630 Identity *id; 1631 1632 TAILQ_FOREACH(id, &authctxt->keys, next) 1633 id->tried = 0; 1634 } 1635 1636 static int 1637 try_identity(Identity *id) 1638 { 1639 if (!id->key) 1640 return (0); 1641 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1642 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1643 debug("Skipped %s key %s for RSA/MD5 server", 1644 sshkey_type(id->key), id->filename); 1645 return (0); 1646 } 1647 return 1; 1648 } 1649 1650 int 1651 userauth_pubkey(Authctxt *authctxt) 1652 { 1653 struct ssh *ssh = active_state; /* XXX */ 1654 Identity *id; 1655 int sent = 0; 1656 char *ident; 1657 1658 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1659 if (id->tried++) 1660 return (0); 1661 /* move key to the end of the queue */ 1662 TAILQ_REMOVE(&authctxt->keys, id, next); 1663 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1664 /* 1665 * send a test message if we have the public key. for 1666 * encrypted keys we cannot do this and have to load the 1667 * private key instead 1668 */ 1669 if (id->key != NULL) { 1670 if (try_identity(id)) { 1671 ident = format_identity(id); 1672 debug("Offering public key: %s", ident); 1673 free(ident); 1674 sent = send_pubkey_test(ssh, authctxt, id); 1675 } 1676 } else { 1677 debug("Trying private key: %s", id->filename); 1678 id->key = load_identity_file(id); 1679 if (id->key != NULL) { 1680 if (try_identity(id)) { 1681 id->isprivate = 1; 1682 sent = sign_and_send_pubkey(ssh, 1683 authctxt, id); 1684 } 1685 sshkey_free(id->key); 1686 id->key = NULL; 1687 id->isprivate = 0; 1688 } 1689 } 1690 if (sent) 1691 return (sent); 1692 } 1693 return (0); 1694 } 1695 1696 /* 1697 * Send userauth request message specifying keyboard-interactive method. 1698 */ 1699 int 1700 userauth_kbdint(Authctxt *authctxt) 1701 { 1702 struct ssh *ssh = active_state; /* XXX */ 1703 int r; 1704 1705 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1706 return 0; 1707 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1708 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1709 debug3("userauth_kbdint: disable: no info_req_seen"); 1710 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1711 return 0; 1712 } 1713 1714 debug2("userauth_kbdint"); 1715 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1716 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1717 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1718 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1719 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1720 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1721 options.kbd_interactive_devices : "")) != 0 || 1722 (r = sshpkt_send(ssh)) != 0) 1723 fatal("%s: %s", __func__, ssh_err(r)); 1724 1725 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1726 return 1; 1727 } 1728 1729 /* 1730 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1731 */ 1732 int 1733 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1734 { 1735 Authctxt *authctxt = ssh->authctxt; 1736 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1737 char *response = NULL; 1738 u_char echo = 0; 1739 u_int num_prompts, i; 1740 int r; 1741 1742 debug2("input_userauth_info_req"); 1743 1744 if (authctxt == NULL) 1745 fatal("input_userauth_info_req: no authentication context"); 1746 1747 authctxt->info_req_seen = 1; 1748 1749 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1750 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1751 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1752 goto out; 1753 if (strlen(name) > 0) 1754 logit("%s", name); 1755 if (strlen(inst) > 0) 1756 logit("%s", inst); 1757 1758 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1759 goto out; 1760 /* 1761 * Begin to build info response packet based on prompts requested. 1762 * We commit to providing the correct number of responses, so if 1763 * further on we run into a problem that prevents this, we have to 1764 * be sure and clean this up and send a correct error response. 1765 */ 1766 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1767 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1768 goto out; 1769 1770 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1771 for (i = 0; i < num_prompts; i++) { 1772 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1773 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1774 goto out; 1775 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1776 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1777 goto out; 1778 freezero(response, strlen(response)); 1779 free(prompt); 1780 response = prompt = NULL; 1781 } 1782 /* done with parsing incoming message. */ 1783 if ((r = sshpkt_get_end(ssh)) != 0 || 1784 (r = sshpkt_add_padding(ssh, 64)) != 0) 1785 goto out; 1786 r = sshpkt_send(ssh); 1787 out: 1788 if (response) 1789 freezero(response, strlen(response)); 1790 free(prompt); 1791 free(name); 1792 free(inst); 1793 free(lang); 1794 return r; 1795 } 1796 1797 static int 1798 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1799 const u_char *data, size_t datalen) 1800 { 1801 struct sshbuf *b; 1802 struct stat st; 1803 pid_t pid; 1804 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1805 u_char rversion = 0, version = 2; 1806 void (*osigchld)(int); 1807 1808 *sigp = NULL; 1809 *lenp = 0; 1810 1811 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1812 error("%s: not installed: %s", __func__, strerror(errno)); 1813 return -1; 1814 } 1815 if (fflush(stdout) != 0) { 1816 error("%s: fflush: %s", __func__, strerror(errno)); 1817 return -1; 1818 } 1819 if (pipe(to) < 0) { 1820 error("%s: pipe: %s", __func__, strerror(errno)); 1821 return -1; 1822 } 1823 if (pipe(from) < 0) { 1824 error("%s: pipe: %s", __func__, strerror(errno)); 1825 return -1; 1826 } 1827 if ((pid = fork()) < 0) { 1828 error("%s: fork: %s", __func__, strerror(errno)); 1829 return -1; 1830 } 1831 osigchld = signal(SIGCHLD, SIG_DFL); 1832 if (pid == 0) { 1833 /* keep the socket on exec */ 1834 fcntl(sock, F_SETFD, 0); 1835 close(from[0]); 1836 if (dup2(from[1], STDOUT_FILENO) < 0) 1837 fatal("%s: dup2: %s", __func__, strerror(errno)); 1838 close(to[1]); 1839 if (dup2(to[0], STDIN_FILENO) < 0) 1840 fatal("%s: dup2: %s", __func__, strerror(errno)); 1841 close(from[1]); 1842 close(to[0]); 1843 /* Close everything but stdio and the socket */ 1844 for (i = STDERR_FILENO + 1; i < sock; i++) 1845 close(i); 1846 closefrom(sock + 1); 1847 debug3("%s: [child] pid=%ld, exec %s", 1848 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1849 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1850 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1851 strerror(errno)); 1852 } 1853 close(from[1]); 1854 close(to[0]); 1855 1856 if ((b = sshbuf_new()) == NULL) 1857 fatal("%s: sshbuf_new failed", __func__); 1858 /* send # of sock, data to be signed */ 1859 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1860 (r = sshbuf_put_string(b, data, datalen)) != 0) 1861 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1862 if (ssh_msg_send(to[1], version, b) == -1) 1863 fatal("%s: couldn't send request", __func__); 1864 sshbuf_reset(b); 1865 r = ssh_msg_recv(from[0], b); 1866 close(from[0]); 1867 close(to[1]); 1868 if (r < 0) { 1869 error("%s: no reply", __func__); 1870 goto fail; 1871 } 1872 1873 errno = 0; 1874 while (waitpid(pid, &status, 0) < 0) { 1875 if (errno != EINTR) { 1876 error("%s: waitpid %ld: %s", 1877 __func__, (long)pid, strerror(errno)); 1878 goto fail; 1879 } 1880 } 1881 if (!WIFEXITED(status)) { 1882 error("%s: exited abnormally", __func__); 1883 goto fail; 1884 } 1885 if (WEXITSTATUS(status) != 0) { 1886 error("%s: exited with status %d", 1887 __func__, WEXITSTATUS(status)); 1888 goto fail; 1889 } 1890 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1891 error("%s: buffer error: %s", __func__, ssh_err(r)); 1892 goto fail; 1893 } 1894 if (rversion != version) { 1895 error("%s: bad version", __func__); 1896 goto fail; 1897 } 1898 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1899 error("%s: buffer error: %s", __func__, ssh_err(r)); 1900 fail: 1901 signal(SIGCHLD, osigchld); 1902 sshbuf_free(b); 1903 return -1; 1904 } 1905 signal(SIGCHLD, osigchld); 1906 sshbuf_free(b); 1907 1908 return 0; 1909 } 1910 1911 int 1912 userauth_hostbased(Authctxt *authctxt) 1913 { 1914 struct ssh *ssh = active_state; /* XXX */ 1915 struct sshkey *private = NULL; 1916 struct sshbuf *b = NULL; 1917 u_char *sig = NULL, *keyblob = NULL; 1918 char *fp = NULL, *chost = NULL, *lname = NULL; 1919 size_t siglen = 0, keylen = 0; 1920 int i, r, success = 0; 1921 1922 if (authctxt->ktypes == NULL) { 1923 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1924 authctxt->ktypes = authctxt->oktypes; 1925 } 1926 1927 /* 1928 * Work through each listed type pattern in HostbasedKeyTypes, 1929 * trying each hostkey that matches the type in turn. 1930 */ 1931 for (;;) { 1932 if (authctxt->active_ktype == NULL) 1933 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1934 if (authctxt->active_ktype == NULL || 1935 *authctxt->active_ktype == '\0') 1936 break; 1937 debug3("%s: trying key type %s", __func__, 1938 authctxt->active_ktype); 1939 1940 /* check for a useful key */ 1941 private = NULL; 1942 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1943 if (authctxt->sensitive->keys[i] == NULL || 1944 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1945 continue; 1946 if (match_pattern_list( 1947 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1948 authctxt->active_ktype, 0) != 1) 1949 continue; 1950 /* we take and free the key */ 1951 private = authctxt->sensitive->keys[i]; 1952 authctxt->sensitive->keys[i] = NULL; 1953 break; 1954 } 1955 /* Found one */ 1956 if (private != NULL) 1957 break; 1958 /* No more keys of this type; advance */ 1959 authctxt->active_ktype = NULL; 1960 } 1961 if (private == NULL) { 1962 free(authctxt->oktypes); 1963 authctxt->oktypes = authctxt->ktypes = NULL; 1964 authctxt->active_ktype = NULL; 1965 debug("No more client hostkeys for hostbased authentication."); 1966 goto out; 1967 } 1968 1969 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1970 SSH_FP_DEFAULT)) == NULL) { 1971 error("%s: sshkey_fingerprint failed", __func__); 1972 goto out; 1973 } 1974 debug("%s: trying hostkey %s %s", 1975 __func__, sshkey_ssh_name(private), fp); 1976 1977 /* figure out a name for the client host */ 1978 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1979 error("%s: cannot get local ipaddr/name", __func__); 1980 goto out; 1981 } 1982 1983 /* XXX sshbuf_put_stringf? */ 1984 xasprintf(&chost, "%s.", lname); 1985 debug2("%s: chost %s", __func__, chost); 1986 1987 /* construct data */ 1988 if ((b = sshbuf_new()) == NULL) { 1989 error("%s: sshbuf_new failed", __func__); 1990 goto out; 1991 } 1992 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1993 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1994 goto out; 1995 } 1996 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1997 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1998 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1999 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2000 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2001 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2002 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2003 (r = sshbuf_put_cstring(b, chost)) != 0 || 2004 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2005 error("%s: buffer error: %s", __func__, ssh_err(r)); 2006 goto out; 2007 } 2008 2009 #ifdef DEBUG_PK 2010 sshbuf_dump(b, stderr); 2011 #endif 2012 r = ssh_keysign(private, &sig, &siglen, 2013 sshbuf_ptr(b), sshbuf_len(b)); 2014 if (r != 0) { 2015 error("sign using hostkey %s %s failed", 2016 sshkey_ssh_name(private), fp); 2017 goto out; 2018 } 2019 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2020 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2021 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2022 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2023 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2024 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2025 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2026 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2027 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2028 (r = sshpkt_send(ssh)) != 0) { 2029 error("%s: packet error: %s", __func__, ssh_err(r)); 2030 goto out; 2031 } 2032 success = 1; 2033 2034 out: 2035 if (sig != NULL) 2036 freezero(sig, siglen); 2037 free(keyblob); 2038 free(lname); 2039 free(fp); 2040 free(chost); 2041 sshkey_free(private); 2042 sshbuf_free(b); 2043 2044 return success; 2045 } 2046 2047 /* find auth method */ 2048 2049 /* 2050 * given auth method name, if configurable options permit this method fill 2051 * in auth_ident field and return true, otherwise return false. 2052 */ 2053 static int 2054 authmethod_is_enabled(Authmethod *method) 2055 { 2056 if (method == NULL) 2057 return 0; 2058 /* return false if options indicate this method is disabled */ 2059 if (method->enabled == NULL || *method->enabled == 0) 2060 return 0; 2061 /* return false if batch mode is enabled but method needs interactive mode */ 2062 if (method->batch_flag != NULL && *method->batch_flag != 0) 2063 return 0; 2064 return 1; 2065 } 2066 2067 static Authmethod * 2068 authmethod_lookup(const char *name) 2069 { 2070 Authmethod *method = NULL; 2071 if (name != NULL) 2072 for (method = authmethods; method->name != NULL; method++) 2073 if (strcmp(name, method->name) == 0) 2074 return method; 2075 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2076 return NULL; 2077 } 2078 2079 /* XXX internal state */ 2080 static Authmethod *current = NULL; 2081 static char *supported = NULL; 2082 static char *preferred = NULL; 2083 2084 /* 2085 * Given the authentication method list sent by the server, return the 2086 * next method we should try. If the server initially sends a nil list, 2087 * use a built-in default list. 2088 */ 2089 static Authmethod * 2090 authmethod_get(char *authlist) 2091 { 2092 char *name = NULL; 2093 u_int next; 2094 2095 /* Use a suitable default if we're passed a nil list. */ 2096 if (authlist == NULL || strlen(authlist) == 0) 2097 authlist = options.preferred_authentications; 2098 2099 if (supported == NULL || strcmp(authlist, supported) != 0) { 2100 debug3("start over, passed a different list %s", authlist); 2101 free(supported); 2102 supported = xstrdup(authlist); 2103 preferred = options.preferred_authentications; 2104 debug3("preferred %s", preferred); 2105 current = NULL; 2106 } else if (current != NULL && authmethod_is_enabled(current)) 2107 return current; 2108 2109 for (;;) { 2110 if ((name = match_list(preferred, supported, &next)) == NULL) { 2111 debug("No more authentication methods to try."); 2112 current = NULL; 2113 return NULL; 2114 } 2115 preferred += next; 2116 debug3("authmethod_lookup %s", name); 2117 debug3("remaining preferred: %s", preferred); 2118 if ((current = authmethod_lookup(name)) != NULL && 2119 authmethod_is_enabled(current)) { 2120 debug3("authmethod_is_enabled %s", name); 2121 debug("Next authentication method: %s", name); 2122 free(name); 2123 return current; 2124 } 2125 free(name); 2126 } 2127 } 2128 2129 static char * 2130 authmethods_get(void) 2131 { 2132 Authmethod *method = NULL; 2133 struct sshbuf *b; 2134 char *list; 2135 int r; 2136 2137 if ((b = sshbuf_new()) == NULL) 2138 fatal("%s: sshbuf_new failed", __func__); 2139 for (method = authmethods; method->name != NULL; method++) { 2140 if (authmethod_is_enabled(method)) { 2141 if ((r = sshbuf_putf(b, "%s%s", 2142 sshbuf_len(b) ? "," : "", method->name)) != 0) 2143 fatal("%s: buffer error: %s", 2144 __func__, ssh_err(r)); 2145 } 2146 } 2147 if ((list = sshbuf_dup_string(b)) == NULL) 2148 fatal("%s: sshbuf_dup_string failed", __func__); 2149 sshbuf_free(b); 2150 return list; 2151 } 2152