1 /* $OpenBSD: sshconnect2.c,v 1.373 2024/05/17 06:38:00 jsg 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 "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <limits.h> 37 #include <netdb.h> 38 #include <pwd.h> 39 #include <signal.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdarg.h> 43 #include <unistd.h> 44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 45 #include <vis.h> 46 #endif 47 48 #include "openbsd-compat/sys-queue.h" 49 50 #include "xmalloc.h" 51 #include "ssh.h" 52 #include "ssh2.h" 53 #include "sshbuf.h" 54 #include "packet.h" 55 #include "compat.h" 56 #include "cipher.h" 57 #include "sshkey.h" 58 #include "kex.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 #include "ssh-sk.h" 76 #include "sk-api.h" 77 78 #ifdef GSSAPI 79 #include "ssh-gss.h" 80 #endif 81 82 /* import */ 83 extern Options options; 84 85 /* 86 * SSH2 key exchange 87 */ 88 89 static char *xxx_host; 90 static struct sockaddr *xxx_hostaddr; 91 static const struct ssh_conn_info *xxx_conn_info; 92 93 static int 94 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 95 { 96 int r; 97 98 if ((r = sshkey_check_rsa_length(hostkey, 99 options.required_rsa_size)) != 0) 100 fatal_r(r, "Bad server host key"); 101 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 102 xxx_conn_info) == -1) 103 fatal("Host key verification failed."); 104 return 0; 105 } 106 107 /* Returns the first item from a comma-separated algorithm list */ 108 static char * 109 first_alg(const char *algs) 110 { 111 char *ret, *cp; 112 113 ret = xstrdup(algs); 114 if ((cp = strchr(ret, ',')) != NULL) 115 *cp = '\0'; 116 return ret; 117 } 118 119 static char * 120 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 121 const struct ssh_conn_info *cinfo) 122 { 123 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 124 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 125 size_t maxlen; 126 struct hostkeys *hostkeys = NULL; 127 int ktype; 128 u_int i; 129 130 /* Find all hostkeys for this hostname */ 131 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 132 hostkeys = init_hostkeys(); 133 for (i = 0; i < options.num_user_hostfiles; i++) 134 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 135 for (i = 0; i < options.num_system_hostfiles; i++) { 136 load_hostkeys(hostkeys, hostname, 137 options.system_hostfiles[i], 0); 138 } 139 if (options.known_hosts_command != NULL) { 140 load_hostkeys_command(hostkeys, options.known_hosts_command, 141 "ORDER", cinfo, NULL, hostname); 142 } 143 /* 144 * If a plain public key exists that matches the type of the best 145 * preference HostkeyAlgorithms, then use the whole list as is. 146 * Note that we ignore whether the best preference algorithm is a 147 * certificate type, as sshconnect.c will downgrade certs to 148 * plain keys if necessary. 149 */ 150 best = first_alg(options.hostkeyalgorithms); 151 if (lookup_key_in_hostkeys_by_type(hostkeys, 152 sshkey_type_plain(sshkey_type_from_name(best)), 153 sshkey_ecdsa_nid_from_name(best), NULL)) { 154 debug3_f("have matching best-preference key type %s, " 155 "using HostkeyAlgorithms verbatim", best); 156 ret = xstrdup(options.hostkeyalgorithms); 157 goto out; 158 } 159 160 /* 161 * Otherwise, prefer the host key algorithms that match known keys 162 * while keeping the ordering of HostkeyAlgorithms as much as possible. 163 */ 164 oavail = avail = xstrdup(options.hostkeyalgorithms); 165 maxlen = strlen(avail) + 1; 166 first = xmalloc(maxlen); 167 last = xmalloc(maxlen); 168 *first = *last = '\0'; 169 170 #define ALG_APPEND(to, from) \ 171 do { \ 172 if (*to != '\0') \ 173 strlcat(to, ",", maxlen); \ 174 strlcat(to, from, maxlen); \ 175 } while (0) 176 177 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 178 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 179 fatal_f("unknown alg %s", alg); 180 /* 181 * If we have a @cert-authority marker in known_hosts then 182 * prefer all certificate algorithms. 183 */ 184 if (sshkey_type_is_cert(ktype) && 185 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 186 ALG_APPEND(first, alg); 187 continue; 188 } 189 /* If the key appears in known_hosts then prefer it */ 190 if (lookup_key_in_hostkeys_by_type(hostkeys, 191 sshkey_type_plain(ktype), 192 sshkey_ecdsa_nid_from_name(alg), NULL)) { 193 ALG_APPEND(first, alg); 194 continue; 195 } 196 /* Otherwise, put it last */ 197 ALG_APPEND(last, alg); 198 } 199 #undef ALG_APPEND 200 xasprintf(&ret, "%s%s%s", first, 201 (*first == '\0' || *last == '\0') ? "" : ",", last); 202 if (*first != '\0') 203 debug3_f("prefer hostkeyalgs: %s", first); 204 else 205 debug3_f("no algorithms matched; accept original"); 206 out: 207 free(best); 208 free(first); 209 free(last); 210 free(hostname); 211 free(oavail); 212 free_hostkeys(hostkeys); 213 214 return ret; 215 } 216 217 void 218 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 219 const struct ssh_conn_info *cinfo) 220 { 221 char *myproposal[PROPOSAL_MAX]; 222 char *all_key, *hkalgs = NULL; 223 int r, use_known_hosts_order = 0; 224 225 xxx_host = host; 226 xxx_hostaddr = hostaddr; 227 xxx_conn_info = cinfo; 228 229 if (options.rekey_limit || options.rekey_interval) 230 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 231 options.rekey_interval); 232 233 /* 234 * If the user has not specified HostkeyAlgorithms, or has only 235 * appended or removed algorithms from that list then prefer algorithms 236 * that are in the list that are supported by known_hosts keys. 237 */ 238 if (options.hostkeyalgorithms == NULL || 239 options.hostkeyalgorithms[0] == '-' || 240 options.hostkeyalgorithms[0] == '+') 241 use_known_hosts_order = 1; 242 243 /* Expand or fill in HostkeyAlgorithms */ 244 all_key = sshkey_alg_list(0, 0, 1, ','); 245 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 246 kex_default_pk_alg(), all_key)) != 0) 247 fatal_fr(r, "kex_assemble_namelist"); 248 free(all_key); 249 250 if (use_known_hosts_order) 251 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 252 253 kex_proposal_populate_entries(ssh, myproposal, 254 options.kex_algorithms, options.ciphers, options.macs, 255 compression_alg_list(options.compression), 256 hkalgs ? hkalgs : options.hostkeyalgorithms); 257 258 free(hkalgs); 259 260 /* start key exchange */ 261 if ((r = kex_setup(ssh, myproposal)) != 0) 262 fatal_r(r, "kex_setup"); 263 #ifdef WITH_OPENSSL 264 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 265 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 266 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 267 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 270 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 271 # ifdef OPENSSL_HAS_ECC 272 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 273 # endif 274 #endif 275 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 276 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 277 ssh->kex->verify_host_key=&verify_host_key_callback; 278 279 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 280 kex_proposal_free_entries(myproposal); 281 282 #ifdef DEBUG_KEXDH 283 /* send 1st encrypted/maced/compressed message */ 284 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 285 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 286 (r = sshpkt_send(ssh)) != 0 || 287 (r = ssh_packet_write_wait(ssh)) != 0) 288 fatal_fr(r, "send packet"); 289 #endif 290 } 291 292 /* 293 * Authenticate user 294 */ 295 296 typedef struct cauthctxt Authctxt; 297 typedef struct cauthmethod Authmethod; 298 typedef struct identity Identity; 299 typedef struct idlist Idlist; 300 301 struct identity { 302 TAILQ_ENTRY(identity) next; 303 int agent_fd; /* >=0 if agent supports key */ 304 struct sshkey *key; /* public/private key */ 305 char *filename; /* comment for agent-only keys */ 306 int tried; 307 int isprivate; /* key points to the private key */ 308 int userprovided; 309 }; 310 TAILQ_HEAD(idlist, identity); 311 312 struct cauthctxt { 313 const char *server_user; 314 const char *local_user; 315 const char *host; 316 const char *service; 317 struct cauthmethod *method; 318 sig_atomic_t success; 319 char *authlist; 320 #ifdef GSSAPI 321 /* gssapi */ 322 gss_OID_set gss_supported_mechs; 323 u_int mech_tried; 324 #endif 325 /* pubkey */ 326 struct idlist keys; 327 int agent_fd; 328 /* hostbased */ 329 Sensitive *sensitive; 330 char *oktypes, *ktypes; 331 const char *active_ktype; 332 /* kbd-interactive */ 333 int info_req_seen; 334 int attempt_kbdint; 335 /* password */ 336 int attempt_passwd; 337 /* generic */ 338 void *methoddata; 339 }; 340 341 struct cauthmethod { 342 char *name; /* string to compare against server's list */ 343 int (*userauth)(struct ssh *ssh); 344 void (*cleanup)(struct ssh *ssh); 345 int *enabled; /* flag in option struct that enables method */ 346 int *batch_flag; /* flag in option struct that disables method */ 347 }; 348 349 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 350 static int input_userauth_success(int, u_int32_t, struct ssh *); 351 static int input_userauth_failure(int, u_int32_t, struct ssh *); 352 static int input_userauth_banner(int, u_int32_t, struct ssh *); 353 static int input_userauth_error(int, u_int32_t, struct ssh *); 354 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 355 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 356 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 357 358 static int userauth_none(struct ssh *); 359 static int userauth_pubkey(struct ssh *); 360 static int userauth_passwd(struct ssh *); 361 static int userauth_kbdint(struct ssh *); 362 static int userauth_hostbased(struct ssh *); 363 364 #ifdef GSSAPI 365 static int userauth_gssapi(struct ssh *); 366 static void userauth_gssapi_cleanup(struct ssh *); 367 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 368 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 369 static int input_gssapi_error(int, u_int32_t, struct ssh *); 370 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 371 #endif 372 373 void userauth(struct ssh *, char *); 374 375 static void pubkey_cleanup(struct ssh *); 376 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 377 static void pubkey_prepare(struct ssh *, Authctxt *); 378 static void pubkey_reset(Authctxt *); 379 static struct sshkey *load_identity_file(Identity *); 380 381 static Authmethod *authmethod_get(char *authlist); 382 static Authmethod *authmethod_lookup(const char *name); 383 static char *authmethods_get(void); 384 385 Authmethod authmethods[] = { 386 #ifdef GSSAPI 387 {"gssapi-with-mic", 388 userauth_gssapi, 389 userauth_gssapi_cleanup, 390 &options.gss_authentication, 391 NULL}, 392 #endif 393 {"hostbased", 394 userauth_hostbased, 395 NULL, 396 &options.hostbased_authentication, 397 NULL}, 398 {"publickey", 399 userauth_pubkey, 400 NULL, 401 &options.pubkey_authentication, 402 NULL}, 403 {"keyboard-interactive", 404 userauth_kbdint, 405 NULL, 406 &options.kbd_interactive_authentication, 407 &options.batch_mode}, 408 {"password", 409 userauth_passwd, 410 NULL, 411 &options.password_authentication, 412 &options.batch_mode}, 413 {"none", 414 userauth_none, 415 NULL, 416 NULL, 417 NULL}, 418 {NULL, NULL, NULL, NULL, NULL} 419 }; 420 421 void 422 ssh_userauth2(struct ssh *ssh, const char *local_user, 423 const char *server_user, char *host, Sensitive *sensitive) 424 { 425 Authctxt authctxt; 426 int r; 427 428 if (options.preferred_authentications == NULL) 429 options.preferred_authentications = authmethods_get(); 430 431 /* setup authentication context */ 432 memset(&authctxt, 0, sizeof(authctxt)); 433 authctxt.server_user = server_user; 434 authctxt.local_user = local_user; 435 authctxt.host = host; 436 authctxt.service = "ssh-connection"; /* service name */ 437 authctxt.success = 0; 438 authctxt.method = authmethod_lookup("none"); 439 authctxt.authlist = NULL; 440 authctxt.methoddata = NULL; 441 authctxt.sensitive = sensitive; 442 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 443 authctxt.info_req_seen = 0; 444 authctxt.attempt_kbdint = 0; 445 authctxt.attempt_passwd = 0; 446 #if GSSAPI 447 authctxt.gss_supported_mechs = NULL; 448 authctxt.mech_tried = 0; 449 #endif 450 authctxt.agent_fd = -1; 451 if (authctxt.method == NULL) 452 fatal_f("internal error: cannot send userauth none request"); 453 454 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 455 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 456 (r = sshpkt_send(ssh)) != 0) 457 fatal_fr(r, "send packet"); 458 459 ssh->authctxt = &authctxt; 460 ssh_dispatch_init(ssh, &input_userauth_error); 461 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 462 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 463 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 464 pubkey_cleanup(ssh); 465 #ifdef GSSAPI 466 if (authctxt.gss_supported_mechs != NULL) { 467 u_int ms; 468 469 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 470 authctxt.gss_supported_mechs = NULL; 471 } 472 #endif 473 ssh->authctxt = NULL; 474 475 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 476 477 if (!authctxt.success) 478 fatal("Authentication failed."); 479 if (ssh_packet_connection_is_on_socket(ssh)) { 480 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 481 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 482 authctxt.method->name); 483 } else { 484 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 485 authctxt.method->name); 486 } 487 } 488 489 static int 490 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 491 { 492 int r; 493 494 if (ssh_packet_remaining(ssh) > 0) { 495 char *reply; 496 497 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 498 goto out; 499 debug2("service_accept: %s", reply); 500 free(reply); 501 } else { 502 debug2("buggy server: service_accept w/o service"); 503 } 504 if ((r = sshpkt_get_end(ssh)) != 0) 505 goto out; 506 debug("SSH2_MSG_SERVICE_ACCEPT received"); 507 508 /* initial userauth request */ 509 userauth_none(ssh); 510 511 /* accept EXT_INFO at any time during userauth */ 512 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 513 &kex_input_ext_info : &input_userauth_error); 514 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 515 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 516 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 517 r = 0; 518 out: 519 return r; 520 } 521 522 void 523 userauth(struct ssh *ssh, char *authlist) 524 { 525 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 526 527 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 528 authctxt->method->cleanup(ssh); 529 530 free(authctxt->methoddata); 531 authctxt->methoddata = NULL; 532 if (authlist == NULL) { 533 authlist = authctxt->authlist; 534 } else { 535 free(authctxt->authlist); 536 authctxt->authlist = authlist; 537 } 538 for (;;) { 539 Authmethod *method = authmethod_get(authlist); 540 if (method == NULL) 541 fatal("%s@%s: Permission denied (%s).", 542 authctxt->server_user, authctxt->host, authlist); 543 authctxt->method = method; 544 545 /* reset the per method handler */ 546 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 547 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 548 549 /* and try new method */ 550 if (method->userauth(ssh) != 0) { 551 debug2("we sent a %s packet, wait for reply", method->name); 552 break; 553 } else { 554 debug2("we did not send a packet, disable method"); 555 method->enabled = NULL; 556 } 557 } 558 } 559 560 static int 561 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 562 { 563 fatal_f("bad message during authentication: type %d", type); 564 return 0; 565 } 566 567 static int 568 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 569 { 570 char *msg = NULL; 571 size_t len; 572 int r; 573 574 debug3_f("entering"); 575 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 576 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 577 goto out; 578 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 579 fmprintf(stderr, "%s", msg); 580 r = 0; 581 out: 582 free(msg); 583 return r; 584 } 585 586 static int 587 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 588 { 589 Authctxt *authctxt = ssh->authctxt; 590 591 if (authctxt == NULL) 592 fatal_f("no authentication context"); 593 free(authctxt->authlist); 594 authctxt->authlist = NULL; 595 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 596 authctxt->method->cleanup(ssh); 597 free(authctxt->methoddata); 598 authctxt->methoddata = NULL; 599 authctxt->success = 1; /* break out */ 600 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 601 return 0; 602 } 603 604 #if 0 605 static int 606 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 607 { 608 Authctxt *authctxt = ssh->authctxt; 609 610 if (authctxt == NULL) 611 fatal_f("no authentication context"); 612 613 fatal("Unexpected authentication success during %s.", 614 authctxt->method->name); 615 return 0; 616 } 617 #endif 618 619 static int 620 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 621 { 622 Authctxt *authctxt = ssh->authctxt; 623 char *authlist = NULL; 624 u_char partial; 625 626 if (authctxt == NULL) 627 fatal("input_userauth_failure: no authentication context"); 628 629 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 630 sshpkt_get_u8(ssh, &partial) != 0 || 631 sshpkt_get_end(ssh) != 0) 632 goto out; 633 634 if (partial != 0) { 635 verbose("Authenticated using \"%s\" with partial success.", 636 authctxt->method->name); 637 /* reset state */ 638 pubkey_reset(authctxt); 639 } 640 debug("Authentications that can continue: %s", authlist); 641 642 userauth(ssh, authlist); 643 authlist = NULL; 644 out: 645 free(authlist); 646 return 0; 647 } 648 649 /* 650 * Format an identity for logging including filename, key type, fingerprint 651 * and location (agent, etc.). Caller must free. 652 */ 653 static char * 654 format_identity(Identity *id) 655 { 656 char *fp = NULL, *ret = NULL; 657 const char *note = ""; 658 659 if (id->key != NULL) { 660 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 661 SSH_FP_DEFAULT); 662 } 663 if (id->key) { 664 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 665 note = " token"; 666 else if (sshkey_is_sk(id->key)) 667 note = " authenticator"; 668 } 669 xasprintf(&ret, "%s %s%s%s%s%s%s", 670 id->filename, 671 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 672 fp ? fp : "", 673 id->userprovided ? " explicit" : "", note, 674 id->agent_fd != -1 ? " agent" : ""); 675 free(fp); 676 return ret; 677 } 678 679 static int 680 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 681 { 682 Authctxt *authctxt = ssh->authctxt; 683 struct sshkey *key = NULL; 684 Identity *id = NULL; 685 int pktype, found = 0, sent = 0; 686 size_t blen; 687 char *pkalg = NULL, *fp = NULL, *ident = NULL; 688 u_char *pkblob = NULL; 689 int r; 690 691 if (authctxt == NULL) 692 fatal("input_userauth_pk_ok: no authentication context"); 693 694 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 695 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 696 (r = sshpkt_get_end(ssh)) != 0) 697 goto done; 698 699 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 700 debug_f("server sent unknown pkalg %s", pkalg); 701 goto done; 702 } 703 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 704 debug_r(r, "no key from blob. pkalg %s", pkalg); 705 goto done; 706 } 707 if (key->type != pktype) { 708 error("input_userauth_pk_ok: type mismatch " 709 "for decoded key (received %d, expected %d)", 710 key->type, pktype); 711 goto done; 712 } 713 714 /* 715 * search keys in the reverse order, because last candidate has been 716 * moved to the end of the queue. this also avoids confusion by 717 * duplicate keys 718 */ 719 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 720 if (sshkey_equal(key, id->key)) { 721 found = 1; 722 break; 723 } 724 } 725 if (!found || id == NULL) { 726 fp = sshkey_fingerprint(key, options.fingerprint_hash, 727 SSH_FP_DEFAULT); 728 error_f("server replied with unknown key: %s %s", 729 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 730 goto done; 731 } 732 ident = format_identity(id); 733 debug("Server accepts key: %s", ident); 734 sent = sign_and_send_pubkey(ssh, id); 735 r = 0; 736 done: 737 sshkey_free(key); 738 free(ident); 739 free(fp); 740 free(pkalg); 741 free(pkblob); 742 743 /* try another method if we did not send a packet */ 744 if (r == 0 && sent == 0) 745 userauth(ssh, NULL); 746 return r; 747 } 748 749 #ifdef GSSAPI 750 static int 751 userauth_gssapi(struct ssh *ssh) 752 { 753 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 754 Gssctxt *gssctxt = NULL; 755 OM_uint32 min; 756 int r, ok = 0; 757 gss_OID mech = NULL; 758 759 /* Try one GSSAPI method at a time, rather than sending them all at 760 * once. */ 761 762 if (authctxt->gss_supported_mechs == NULL) 763 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 764 765 /* Check to see whether the mechanism is usable before we offer it */ 766 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 767 !ok) { 768 mech = &authctxt->gss_supported_mechs-> 769 elements[authctxt->mech_tried]; 770 /* My DER encoding requires length<128 */ 771 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 772 mech, authctxt->host)) { 773 ok = 1; /* Mechanism works */ 774 } else { 775 authctxt->mech_tried++; 776 } 777 } 778 779 if (!ok || mech == NULL) 780 return 0; 781 782 authctxt->methoddata=(void *)gssctxt; 783 784 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 785 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 786 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 787 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 788 (r = sshpkt_put_u32(ssh, 1)) != 0 || 789 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 790 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 791 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 792 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 793 (r = sshpkt_send(ssh)) != 0) 794 fatal_fr(r, "send packet"); 795 796 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 797 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 798 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 800 801 authctxt->mech_tried++; /* Move along to next candidate */ 802 803 return 1; 804 } 805 806 static void 807 userauth_gssapi_cleanup(struct ssh *ssh) 808 { 809 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 810 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 811 812 ssh_gssapi_delete_ctx(&gssctxt); 813 authctxt->methoddata = NULL; 814 } 815 816 static OM_uint32 817 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 818 { 819 Authctxt *authctxt = ssh->authctxt; 820 Gssctxt *gssctxt = authctxt->methoddata; 821 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 822 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 823 gss_buffer_desc gssbuf; 824 OM_uint32 status, ms, flags; 825 int r; 826 827 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 828 recv_tok, &send_tok, &flags); 829 830 if (send_tok.length > 0) { 831 u_char type = GSS_ERROR(status) ? 832 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 833 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 834 835 if ((r = sshpkt_start(ssh, type)) != 0 || 836 (r = sshpkt_put_string(ssh, send_tok.value, 837 send_tok.length)) != 0 || 838 (r = sshpkt_send(ssh)) != 0) 839 fatal_fr(r, "send %u packet", type); 840 841 gss_release_buffer(&ms, &send_tok); 842 } 843 844 if (status == GSS_S_COMPLETE) { 845 /* send either complete or MIC, depending on mechanism */ 846 if (!(flags & GSS_C_INTEG_FLAG)) { 847 if ((r = sshpkt_start(ssh, 848 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 849 (r = sshpkt_send(ssh)) != 0) 850 fatal_fr(r, "send completion"); 851 } else { 852 struct sshbuf *b; 853 854 if ((b = sshbuf_new()) == NULL) 855 fatal_f("sshbuf_new failed"); 856 ssh_gssapi_buildmic(b, authctxt->server_user, 857 authctxt->service, "gssapi-with-mic", 858 ssh->kex->session_id); 859 860 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 861 fatal_f("sshbuf_mutable_ptr failed"); 862 gssbuf.length = sshbuf_len(b); 863 864 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 865 866 if (!GSS_ERROR(status)) { 867 if ((r = sshpkt_start(ssh, 868 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 869 (r = sshpkt_put_string(ssh, mic.value, 870 mic.length)) != 0 || 871 (r = sshpkt_send(ssh)) != 0) 872 fatal_fr(r, "send MIC"); 873 } 874 875 sshbuf_free(b); 876 gss_release_buffer(&ms, &mic); 877 } 878 } 879 880 return status; 881 } 882 883 static int 884 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 885 { 886 Authctxt *authctxt = ssh->authctxt; 887 Gssctxt *gssctxt; 888 size_t oidlen; 889 u_char *oidv = NULL; 890 int r; 891 892 if (authctxt == NULL) 893 fatal("input_gssapi_response: no authentication context"); 894 gssctxt = authctxt->methoddata; 895 896 /* Setup our OID */ 897 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 898 goto done; 899 900 if (oidlen <= 2 || 901 oidv[0] != SSH_GSS_OIDTYPE || 902 oidv[1] != oidlen - 2) { 903 debug("Badly encoded mechanism OID received"); 904 userauth(ssh, NULL); 905 goto ok; 906 } 907 908 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 909 fatal("Server returned different OID than expected"); 910 911 if ((r = sshpkt_get_end(ssh)) != 0) 912 goto done; 913 914 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 915 /* Start again with next method on list */ 916 debug("Trying to start again"); 917 userauth(ssh, NULL); 918 goto ok; 919 } 920 ok: 921 r = 0; 922 done: 923 free(oidv); 924 return r; 925 } 926 927 static int 928 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 929 { 930 Authctxt *authctxt = ssh->authctxt; 931 gss_buffer_desc recv_tok; 932 u_char *p = NULL; 933 size_t len; 934 OM_uint32 status; 935 int r; 936 937 if (authctxt == NULL) 938 fatal("input_gssapi_response: no authentication context"); 939 940 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 941 (r = sshpkt_get_end(ssh)) != 0) 942 goto out; 943 944 recv_tok.value = p; 945 recv_tok.length = len; 946 status = process_gssapi_token(ssh, &recv_tok); 947 948 /* Start again with the next method in the list */ 949 if (GSS_ERROR(status)) { 950 userauth(ssh, NULL); 951 /* ok */ 952 } 953 r = 0; 954 out: 955 free(p); 956 return r; 957 } 958 959 static int 960 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 961 { 962 Authctxt *authctxt = ssh->authctxt; 963 Gssctxt *gssctxt; 964 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 965 gss_buffer_desc recv_tok; 966 OM_uint32 ms; 967 u_char *p = NULL; 968 size_t len; 969 int r; 970 971 if (authctxt == NULL) 972 fatal("input_gssapi_response: no authentication context"); 973 gssctxt = authctxt->methoddata; 974 975 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 976 (r = sshpkt_get_end(ssh)) != 0) { 977 free(p); 978 return r; 979 } 980 981 /* Stick it into GSSAPI and see what it says */ 982 recv_tok.value = p; 983 recv_tok.length = len; 984 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 985 &recv_tok, &send_tok, NULL); 986 free(p); 987 gss_release_buffer(&ms, &send_tok); 988 989 /* Server will be returning a failed packet after this one */ 990 return 0; 991 } 992 993 static int 994 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 995 { 996 char *msg = NULL; 997 char *lang = NULL; 998 int r; 999 1000 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1001 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1002 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1003 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1004 goto out; 1005 r = sshpkt_get_end(ssh); 1006 debug("Server GSSAPI Error:\n%s", msg); 1007 out: 1008 free(msg); 1009 free(lang); 1010 return r; 1011 } 1012 #endif /* GSSAPI */ 1013 1014 static int 1015 userauth_none(struct ssh *ssh) 1016 { 1017 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1018 int r; 1019 1020 /* initial userauth request */ 1021 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1022 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1023 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1024 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1025 (r = sshpkt_send(ssh)) != 0) 1026 fatal_fr(r, "send packet"); 1027 return 1; 1028 } 1029 1030 static int 1031 userauth_passwd(struct ssh *ssh) 1032 { 1033 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1034 char *password, *prompt = NULL; 1035 const char *host = options.host_key_alias ? options.host_key_alias : 1036 authctxt->host; 1037 int r; 1038 1039 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1040 return 0; 1041 1042 if (authctxt->attempt_passwd != 1) 1043 error("Permission denied, please try again."); 1044 1045 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1046 password = read_passphrase(prompt, 0); 1047 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1048 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1049 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1050 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1051 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1052 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1053 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1054 (r = sshpkt_send(ssh)) != 0) 1055 fatal_fr(r, "send packet"); 1056 1057 free(prompt); 1058 if (password != NULL) 1059 freezero(password, strlen(password)); 1060 1061 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1062 &input_userauth_passwd_changereq); 1063 1064 return 1; 1065 } 1066 1067 /* 1068 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1069 */ 1070 static int 1071 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1072 { 1073 Authctxt *authctxt = ssh->authctxt; 1074 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1075 char prompt[256]; 1076 const char *host; 1077 int r; 1078 1079 debug2("input_userauth_passwd_changereq"); 1080 1081 if (authctxt == NULL) 1082 fatal("input_userauth_passwd_changereq: " 1083 "no authentication context"); 1084 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1085 1086 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1087 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1088 goto out; 1089 if (strlen(info) > 0) 1090 logit("%s", info); 1091 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1092 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1093 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1094 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1095 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1096 goto out; 1097 1098 snprintf(prompt, sizeof(prompt), 1099 "Enter %.30s@%.128s's old password: ", 1100 authctxt->server_user, host); 1101 password = read_passphrase(prompt, 0); 1102 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1103 goto out; 1104 1105 freezero(password, strlen(password)); 1106 password = NULL; 1107 while (password == NULL) { 1108 snprintf(prompt, sizeof(prompt), 1109 "Enter %.30s@%.128s's new password: ", 1110 authctxt->server_user, host); 1111 password = read_passphrase(prompt, RP_ALLOW_EOF); 1112 if (password == NULL) { 1113 /* bail out */ 1114 r = 0; 1115 goto out; 1116 } 1117 snprintf(prompt, sizeof(prompt), 1118 "Retype %.30s@%.128s's new password: ", 1119 authctxt->server_user, host); 1120 retype = read_passphrase(prompt, 0); 1121 if (strcmp(password, retype) != 0) { 1122 freezero(password, strlen(password)); 1123 logit("Mismatch; try again, EOF to quit."); 1124 password = NULL; 1125 } 1126 freezero(retype, strlen(retype)); 1127 } 1128 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1129 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1130 (r = sshpkt_send(ssh)) != 0) 1131 goto out; 1132 1133 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1134 &input_userauth_passwd_changereq); 1135 r = 0; 1136 out: 1137 if (password) 1138 freezero(password, strlen(password)); 1139 free(info); 1140 free(lang); 1141 return r; 1142 } 1143 1144 /* 1145 * Select an algorithm for publickey signatures. 1146 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1147 * 1148 * Call with ssh==NULL to ignore server-sig-algs extension list and 1149 * only attempt with the key's base signature type. 1150 */ 1151 static char * 1152 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1153 { 1154 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1155 const char *server_sig_algs; 1156 1157 /* 1158 * The signature algorithm will only differ from the key algorithm 1159 * for RSA keys/certs and when the server advertises support for 1160 * newer (SHA2) algorithms. 1161 */ 1162 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1163 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1164 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1165 /* Filter base key signature alg against our configuration */ 1166 return match_list(sshkey_ssh_name(key), 1167 options.pubkey_accepted_algos, NULL); 1168 } 1169 1170 /* 1171 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1172 * fails to advertise it via SSH2_MSG_EXT_INFO. 1173 */ 1174 server_sig_algs = ssh->kex->server_sig_algs; 1175 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1176 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1177 1178 /* 1179 * For RSA keys/certs, since these might have a different sig type: 1180 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1181 * that also appears in the supported signature algorithms list from 1182 * the server. 1183 */ 1184 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1185 while ((cp = strsep(&allowed, ",")) != NULL) { 1186 if (sshkey_type_from_name(cp) != key->type) 1187 continue; 1188 tmp = match_list(sshkey_sigalg_by_name(cp), 1189 server_sig_algs, NULL); 1190 if (tmp != NULL) 1191 alg = xstrdup(cp); 1192 free(tmp); 1193 if (alg != NULL) 1194 break; 1195 } 1196 free(oallowed); 1197 return alg; 1198 } 1199 1200 static int 1201 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1202 const u_char *data, size_t datalen, u_int compat, const char *alg) 1203 { 1204 struct sshkey *sign_key = NULL, *prv = NULL; 1205 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1206 struct notifier_ctx *notifier = NULL; 1207 char *fp = NULL, *pin = NULL, *prompt = NULL; 1208 1209 *sigp = NULL; 1210 *lenp = 0; 1211 1212 /* The agent supports this key. */ 1213 if (id->key != NULL && id->agent_fd != -1) { 1214 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1215 data, datalen, alg, compat); 1216 } 1217 1218 /* 1219 * We have already loaded the private key or the private key is 1220 * stored in external hardware. 1221 */ 1222 if (id->key != NULL && 1223 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1224 sign_key = id->key; 1225 is_agent = 1; 1226 } else { 1227 /* Load the private key from the file. */ 1228 if ((prv = load_identity_file(id)) == NULL) 1229 return SSH_ERR_KEY_NOT_FOUND; 1230 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1231 error_f("private key %s contents do not match public", 1232 id->filename); 1233 r = SSH_ERR_KEY_NOT_FOUND; 1234 goto out; 1235 } 1236 sign_key = prv; 1237 } 1238 retry_pin: 1239 /* Prompt for touch for non-agent FIDO keys that request UP */ 1240 if (!is_agent && sshkey_is_sk(sign_key) && 1241 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1242 /* XXX should batch mode just skip these? */ 1243 if ((fp = sshkey_fingerprint(sign_key, 1244 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1245 fatal_f("fingerprint failed"); 1246 notifier = notify_start(options.batch_mode, 1247 "Confirm user presence for key %s %s", 1248 sshkey_type(sign_key), fp); 1249 free(fp); 1250 } 1251 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1252 alg, options.sk_provider, pin, compat)) != 0) { 1253 debug_fr(r, "sshkey_sign"); 1254 if (!retried && pin == NULL && !is_agent && 1255 sshkey_is_sk(sign_key) && 1256 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1257 notify_complete(notifier, NULL); 1258 notifier = NULL; 1259 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1260 sshkey_type(sign_key), id->filename); 1261 pin = read_passphrase(prompt, 0); 1262 retried = 1; 1263 goto retry_pin; 1264 } 1265 goto out; 1266 } 1267 1268 /* 1269 * PKCS#11 tokens may not support all signature algorithms, 1270 * so check what we get back. 1271 */ 1272 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1273 debug_fr(r, "sshkey_check_sigtype"); 1274 goto out; 1275 } 1276 /* success */ 1277 r = 0; 1278 out: 1279 free(prompt); 1280 if (pin != NULL) 1281 freezero(pin, strlen(pin)); 1282 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1283 sshkey_free(prv); 1284 return r; 1285 } 1286 1287 static int 1288 id_filename_matches(Identity *id, Identity *private_id) 1289 { 1290 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1291 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1292 size_t i, slen; 1293 1294 if (strcmp(id->filename, private_id->filename) == 0) 1295 return 1; 1296 for (i = 0; suffixes[i]; i++) { 1297 slen = strlen(suffixes[i]); 1298 if (len > slen && plen == len - slen && 1299 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1300 memcmp(id->filename, private_id->filename, plen) == 0) 1301 return 1; 1302 } 1303 return 0; 1304 } 1305 1306 static int 1307 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1308 { 1309 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1310 struct sshbuf *b = NULL; 1311 Identity *private_id, *sign_id = NULL; 1312 u_char *signature = NULL; 1313 size_t slen = 0, skip = 0; 1314 int r, fallback_sigtype, sent = 0; 1315 char *alg = NULL, *fp = NULL; 1316 const char *loc = "", *method = "publickey"; 1317 int hostbound = 0; 1318 1319 /* prefer host-bound pubkey signatures if supported by server */ 1320 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1321 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1322 hostbound = 1; 1323 method = "publickey-hostbound-v00@openssh.com"; 1324 } 1325 1326 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1327 SSH_FP_DEFAULT)) == NULL) 1328 return 0; 1329 1330 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1331 1332 /* 1333 * If the key is an certificate, try to find a matching private key 1334 * and use it to complete the signature. 1335 * If no such private key exists, fall back to trying the certificate 1336 * key itself in case it has a private half already loaded. 1337 * This will try to set sign_id to the private key that will perform 1338 * the signature. 1339 */ 1340 if (sshkey_is_cert(id->key)) { 1341 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1342 if (sshkey_equal_public(id->key, private_id->key) && 1343 id->key->type != private_id->key->type) { 1344 sign_id = private_id; 1345 break; 1346 } 1347 } 1348 /* 1349 * Exact key matches are preferred, but also allow 1350 * filename matches for non-PKCS#11/agent keys that 1351 * didn't load public keys. This supports the case 1352 * of keeping just a private key file and public 1353 * certificate on disk. 1354 */ 1355 if (sign_id == NULL && 1356 !id->isprivate && id->agent_fd == -1 && 1357 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1358 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1359 if (private_id->key == NULL && 1360 id_filename_matches(id, private_id)) { 1361 sign_id = private_id; 1362 break; 1363 } 1364 } 1365 } 1366 if (sign_id != NULL) { 1367 debug2_f("using private key \"%s\"%s for " 1368 "certificate", sign_id->filename, 1369 sign_id->agent_fd != -1 ? " from agent" : ""); 1370 } else { 1371 debug_f("no separate private key for certificate " 1372 "\"%s\"", id->filename); 1373 } 1374 } 1375 1376 /* 1377 * If the above didn't select another identity to do the signing 1378 * then default to the one we started with. 1379 */ 1380 if (sign_id == NULL) 1381 sign_id = id; 1382 1383 /* assemble and sign data */ 1384 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1385 free(alg); 1386 slen = 0; 1387 signature = NULL; 1388 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1389 id->key)) == NULL) { 1390 error_f("no mutual signature supported"); 1391 goto out; 1392 } 1393 debug3_f("signing using %s %s", alg, fp); 1394 1395 sshbuf_free(b); 1396 if ((b = sshbuf_new()) == NULL) 1397 fatal_f("sshbuf_new failed"); 1398 if (ssh->compat & SSH_OLD_SESSIONID) { 1399 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1400 fatal_fr(r, "sshbuf_putb"); 1401 } else { 1402 if ((r = sshbuf_put_stringb(b, 1403 ssh->kex->session_id)) != 0) 1404 fatal_fr(r, "sshbuf_put_stringb"); 1405 } 1406 skip = sshbuf_len(b); 1407 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1408 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1409 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1410 (r = sshbuf_put_cstring(b, method)) != 0 || 1411 (r = sshbuf_put_u8(b, 1)) != 0 || 1412 (r = sshbuf_put_cstring(b, alg)) != 0 || 1413 (r = sshkey_puts(id->key, b)) != 0) { 1414 fatal_fr(r, "assemble signed data"); 1415 } 1416 if (hostbound) { 1417 if (ssh->kex->initial_hostkey == NULL) { 1418 fatal_f("internal error: initial hostkey " 1419 "not recorded"); 1420 } 1421 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1422 fatal_fr(r, "assemble %s hostkey", method); 1423 } 1424 /* generate signature */ 1425 r = identity_sign(sign_id, &signature, &slen, 1426 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1427 if (r == 0) 1428 break; 1429 else if (r == SSH_ERR_KEY_NOT_FOUND) 1430 goto out; /* soft failure */ 1431 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1432 !fallback_sigtype) { 1433 if (sign_id->agent_fd != -1) 1434 loc = "agent "; 1435 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1436 loc = "token "; 1437 logit("%skey %s %s returned incorrect signature type", 1438 loc, sshkey_type(id->key), fp); 1439 continue; 1440 } 1441 error_fr(r, "signing failed for %s \"%s\"%s", 1442 sshkey_type(sign_id->key), sign_id->filename, 1443 id->agent_fd != -1 ? " from agent" : ""); 1444 goto out; 1445 } 1446 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1447 fatal_f("no signature"); 1448 1449 /* append signature */ 1450 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1451 fatal_fr(r, "append signature"); 1452 1453 #ifdef DEBUG_PK 1454 sshbuf_dump(b, stderr); 1455 #endif 1456 /* skip session id and packet type */ 1457 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1458 fatal_fr(r, "consume"); 1459 1460 /* put remaining data from buffer into packet */ 1461 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1462 (r = sshpkt_putb(ssh, b)) != 0 || 1463 (r = sshpkt_send(ssh)) != 0) 1464 fatal_fr(r, "enqueue request"); 1465 1466 /* success */ 1467 sent = 1; 1468 1469 out: 1470 free(fp); 1471 free(alg); 1472 sshbuf_free(b); 1473 freezero(signature, slen); 1474 return sent; 1475 } 1476 1477 static int 1478 send_pubkey_test(struct ssh *ssh, Identity *id) 1479 { 1480 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1481 u_char *blob = NULL; 1482 char *alg = NULL; 1483 size_t bloblen; 1484 u_int have_sig = 0; 1485 int sent = 0, r; 1486 1487 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1488 debug_f("no mutual signature algorithm"); 1489 goto out; 1490 } 1491 1492 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1493 /* we cannot handle this key */ 1494 debug3_f("cannot handle key"); 1495 goto out; 1496 } 1497 /* register callback for USERAUTH_PK_OK message */ 1498 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1499 1500 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1501 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1502 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1503 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1504 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1505 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1506 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1507 (r = sshpkt_send(ssh)) != 0) 1508 fatal_fr(r, "send packet"); 1509 sent = 1; 1510 1511 out: 1512 free(alg); 1513 free(blob); 1514 return sent; 1515 } 1516 1517 static struct sshkey * 1518 load_identity_file(Identity *id) 1519 { 1520 struct sshkey *private = NULL; 1521 char prompt[300], *passphrase, *comment; 1522 int r, quit = 0, i; 1523 struct stat st; 1524 1525 if (stat(id->filename, &st) == -1) { 1526 do_log2(id->userprovided ? 1527 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1528 "no such identity: %s: %s", id->filename, strerror(errno)); 1529 return NULL; 1530 } 1531 snprintf(prompt, sizeof prompt, 1532 "Enter passphrase for key '%.100s': ", id->filename); 1533 for (i = 0; i <= options.number_of_password_prompts; i++) { 1534 if (i == 0) 1535 passphrase = ""; 1536 else { 1537 passphrase = read_passphrase(prompt, 0); 1538 if (*passphrase == '\0') { 1539 debug2("no passphrase given, try next key"); 1540 free(passphrase); 1541 break; 1542 } 1543 } 1544 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1545 passphrase, &private, &comment))) { 1546 case 0: 1547 break; 1548 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1549 if (options.batch_mode) { 1550 quit = 1; 1551 break; 1552 } 1553 if (i != 0) 1554 debug2("bad passphrase given, try again..."); 1555 break; 1556 case SSH_ERR_SYSTEM_ERROR: 1557 if (errno == ENOENT) { 1558 debug2_r(r, "Load key \"%s\"", id->filename); 1559 quit = 1; 1560 break; 1561 } 1562 /* FALLTHROUGH */ 1563 default: 1564 error_r(r, "Load key \"%s\"", id->filename); 1565 quit = 1; 1566 break; 1567 } 1568 if (private != NULL && sshkey_is_sk(private) && 1569 options.sk_provider == NULL) { 1570 debug("key \"%s\" is an authenticator-hosted key, " 1571 "but no provider specified", id->filename); 1572 sshkey_free(private); 1573 private = NULL; 1574 quit = 1; 1575 } 1576 if (!quit && (r = sshkey_check_rsa_length(private, 1577 options.required_rsa_size)) != 0) { 1578 debug_fr(r, "Skipping key %s", id->filename); 1579 sshkey_free(private); 1580 private = NULL; 1581 quit = 1; 1582 } 1583 if (!quit && private != NULL && id->agent_fd == -1 && 1584 !(id->key && id->isprivate)) 1585 maybe_add_key_to_agent(id->filename, private, comment, 1586 passphrase); 1587 if (i > 0) 1588 freezero(passphrase, strlen(passphrase)); 1589 free(comment); 1590 if (private != NULL || quit) 1591 break; 1592 } 1593 return private; 1594 } 1595 1596 static int 1597 key_type_allowed_by_config(struct sshkey *key) 1598 { 1599 if (match_pattern_list(sshkey_ssh_name(key), 1600 options.pubkey_accepted_algos, 0) == 1) 1601 return 1; 1602 1603 /* RSA keys/certs might be allowed by alternate signature types */ 1604 switch (key->type) { 1605 case KEY_RSA: 1606 if (match_pattern_list("rsa-sha2-512", 1607 options.pubkey_accepted_algos, 0) == 1) 1608 return 1; 1609 if (match_pattern_list("rsa-sha2-256", 1610 options.pubkey_accepted_algos, 0) == 1) 1611 return 1; 1612 break; 1613 case KEY_RSA_CERT: 1614 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1615 options.pubkey_accepted_algos, 0) == 1) 1616 return 1; 1617 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1618 options.pubkey_accepted_algos, 0) == 1) 1619 return 1; 1620 break; 1621 } 1622 return 0; 1623 } 1624 1625 /* obtain a list of keys from the agent */ 1626 static int 1627 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1628 struct ssh_identitylist **idlistp) 1629 { 1630 int r, agent_fd; 1631 struct ssh_identitylist *idlist; 1632 1633 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1634 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1635 debug_fr(r, "ssh_get_authentication_socket"); 1636 return r; 1637 } 1638 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1639 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1640 debug_f("bound agent to hostkey"); 1641 else 1642 debug2_fr(r, "ssh_agent_bind_hostkey"); 1643 1644 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1645 debug_fr(r, "ssh_fetch_identitylist"); 1646 close(agent_fd); 1647 return r; 1648 } 1649 /* success */ 1650 *agent_fdp = agent_fd; 1651 *idlistp = idlist; 1652 debug_f("agent returned %zu keys", idlist->nkeys); 1653 return 0; 1654 } 1655 1656 /* 1657 * try keys in the following order: 1658 * 1. certificates listed in the config file 1659 * 2. other input certificates 1660 * 3. agent keys that are found in the config file 1661 * 4. other agent keys 1662 * 5. keys that are only listed in the config file 1663 */ 1664 static void 1665 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1666 { 1667 struct identity *id, *id2, *tmp; 1668 struct idlist agent, files, *preferred; 1669 struct sshkey *key; 1670 int disallowed, agent_fd = -1, i, r, found; 1671 size_t j; 1672 struct ssh_identitylist *idlist; 1673 char *cp, *ident; 1674 1675 TAILQ_INIT(&agent); /* keys from the agent */ 1676 TAILQ_INIT(&files); /* keys from the config file */ 1677 preferred = &authctxt->keys; 1678 TAILQ_INIT(preferred); /* preferred order of keys */ 1679 1680 /* list of keys stored in the filesystem and PKCS#11 */ 1681 for (i = 0; i < options.num_identity_files; i++) { 1682 key = options.identity_keys[i]; 1683 if (key && key->cert && 1684 key->cert->type != SSH2_CERT_TYPE_USER) { 1685 debug_f("ignoring certificate %s: not a user " 1686 "certificate", options.identity_files[i]); 1687 continue; 1688 } 1689 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1690 debug_f("ignoring authenticator-hosted key %s as no " 1691 "SecurityKeyProvider has been specified", 1692 options.identity_files[i]); 1693 continue; 1694 } 1695 options.identity_keys[i] = NULL; 1696 id = xcalloc(1, sizeof(*id)); 1697 id->agent_fd = -1; 1698 id->key = key; 1699 id->filename = xstrdup(options.identity_files[i]); 1700 id->userprovided = options.identity_file_userprovided[i]; 1701 TAILQ_INSERT_TAIL(&files, id, next); 1702 } 1703 /* list of certificates specified by user */ 1704 for (i = 0; i < options.num_certificate_files; i++) { 1705 key = options.certificates[i]; 1706 if (!sshkey_is_cert(key) || key->cert == NULL || 1707 key->cert->type != SSH2_CERT_TYPE_USER) { 1708 debug_f("ignoring certificate %s: not a user " 1709 "certificate", options.identity_files[i]); 1710 continue; 1711 } 1712 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1713 debug_f("ignoring authenticator-hosted key " 1714 "certificate %s as no " 1715 "SecurityKeyProvider has been specified", 1716 options.identity_files[i]); 1717 continue; 1718 } 1719 id = xcalloc(1, sizeof(*id)); 1720 id->agent_fd = -1; 1721 id->key = key; 1722 id->filename = xstrdup(options.certificate_files[i]); 1723 id->userprovided = options.certificate_file_userprovided[i]; 1724 TAILQ_INSERT_TAIL(preferred, id, next); 1725 } 1726 /* list of keys supported by the agent */ 1727 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1728 for (j = 0; j < idlist->nkeys; j++) { 1729 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1730 options.required_rsa_size)) != 0) { 1731 debug_fr(r, "ignoring %s agent key", 1732 sshkey_ssh_name(idlist->keys[j])); 1733 continue; 1734 } 1735 found = 0; 1736 TAILQ_FOREACH(id, &files, next) { 1737 /* 1738 * agent keys from the config file are 1739 * preferred 1740 */ 1741 if (sshkey_equal(idlist->keys[j], id->key)) { 1742 TAILQ_REMOVE(&files, id, next); 1743 TAILQ_INSERT_TAIL(preferred, id, next); 1744 id->agent_fd = agent_fd; 1745 found = 1; 1746 break; 1747 } 1748 } 1749 if (!found && !options.identities_only) { 1750 id = xcalloc(1, sizeof(*id)); 1751 /* XXX "steals" key/comment from idlist */ 1752 id->key = idlist->keys[j]; 1753 id->filename = idlist->comments[j]; 1754 idlist->keys[j] = NULL; 1755 idlist->comments[j] = NULL; 1756 id->agent_fd = agent_fd; 1757 TAILQ_INSERT_TAIL(&agent, id, next); 1758 } 1759 } 1760 ssh_free_identitylist(idlist); 1761 /* append remaining agent keys */ 1762 TAILQ_CONCAT(preferred, &agent, next); 1763 authctxt->agent_fd = agent_fd; 1764 } 1765 /* Prefer PKCS11 keys that are explicitly listed */ 1766 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1767 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1768 continue; 1769 found = 0; 1770 TAILQ_FOREACH(id2, &files, next) { 1771 if (id2->key == NULL || 1772 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1773 continue; 1774 if (sshkey_equal(id->key, id2->key)) { 1775 TAILQ_REMOVE(&files, id, next); 1776 TAILQ_INSERT_TAIL(preferred, id, next); 1777 found = 1; 1778 break; 1779 } 1780 } 1781 /* If IdentitiesOnly set and key not found then don't use it */ 1782 if (!found && options.identities_only) { 1783 TAILQ_REMOVE(&files, id, next); 1784 freezero(id, sizeof(*id)); 1785 } 1786 } 1787 /* append remaining keys from the config file */ 1788 TAILQ_CONCAT(preferred, &files, next); 1789 /* finally, filter by PubkeyAcceptedAlgorithms */ 1790 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1791 disallowed = 0; 1792 cp = NULL; 1793 if (id->key == NULL) 1794 continue; 1795 if (!key_type_allowed_by_config(id->key)) { 1796 debug("Skipping %s key %s - corresponding algorithm " 1797 "not in PubkeyAcceptedAlgorithms", 1798 sshkey_ssh_name(id->key), id->filename); 1799 disallowed = 1; 1800 } else if (ssh->kex->server_sig_algs != NULL && 1801 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1802 debug("Skipping %s key %s - corresponding algorithm " 1803 "not supported by server", 1804 sshkey_ssh_name(id->key), id->filename); 1805 disallowed = 1; 1806 } 1807 free(cp); 1808 if (!disallowed) 1809 continue; 1810 /* remove key */ 1811 TAILQ_REMOVE(preferred, id, next); 1812 sshkey_free(id->key); 1813 free(id->filename); 1814 memset(id, 0, sizeof(*id)); 1815 } 1816 /* List the keys we plan on using */ 1817 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1818 ident = format_identity(id); 1819 debug("Will attempt key: %s", ident); 1820 free(ident); 1821 } 1822 debug2_f("done"); 1823 } 1824 1825 static void 1826 pubkey_cleanup(struct ssh *ssh) 1827 { 1828 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1829 Identity *id; 1830 1831 if (authctxt->agent_fd != -1) { 1832 ssh_close_authentication_socket(authctxt->agent_fd); 1833 authctxt->agent_fd = -1; 1834 } 1835 for (id = TAILQ_FIRST(&authctxt->keys); id; 1836 id = TAILQ_FIRST(&authctxt->keys)) { 1837 TAILQ_REMOVE(&authctxt->keys, id, next); 1838 sshkey_free(id->key); 1839 free(id->filename); 1840 free(id); 1841 } 1842 } 1843 1844 static void 1845 pubkey_reset(Authctxt *authctxt) 1846 { 1847 Identity *id; 1848 1849 TAILQ_FOREACH(id, &authctxt->keys, next) 1850 id->tried = 0; 1851 } 1852 1853 static int 1854 userauth_pubkey(struct ssh *ssh) 1855 { 1856 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1857 Identity *id; 1858 int sent = 0; 1859 char *ident; 1860 static int prepared; 1861 1862 if (!prepared) { 1863 pubkey_prepare(ssh, authctxt); 1864 prepared = 1; 1865 } 1866 1867 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1868 if (id->tried++) 1869 return (0); 1870 /* move key to the end of the queue */ 1871 TAILQ_REMOVE(&authctxt->keys, id, next); 1872 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1873 /* 1874 * send a test message if we have the public key. for 1875 * encrypted keys we cannot do this and have to load the 1876 * private key instead 1877 */ 1878 if (id->key != NULL) { 1879 ident = format_identity(id); 1880 debug("Offering public key: %s", ident); 1881 free(ident); 1882 sent = send_pubkey_test(ssh, id); 1883 } else { 1884 debug("Trying private key: %s", id->filename); 1885 id->key = load_identity_file(id); 1886 if (id->key != NULL) { 1887 if (id->key != NULL) { 1888 id->isprivate = 1; 1889 sent = sign_and_send_pubkey(ssh, id); 1890 } 1891 sshkey_free(id->key); 1892 id->key = NULL; 1893 id->isprivate = 0; 1894 } 1895 } 1896 if (sent) 1897 return (sent); 1898 } 1899 return (0); 1900 } 1901 1902 /* 1903 * Send userauth request message specifying keyboard-interactive method. 1904 */ 1905 static int 1906 userauth_kbdint(struct ssh *ssh) 1907 { 1908 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1909 int r; 1910 1911 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1912 return 0; 1913 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1914 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1915 debug3("userauth_kbdint: disable: no info_req_seen"); 1916 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1917 return 0; 1918 } 1919 1920 debug2("userauth_kbdint"); 1921 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1922 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1923 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1924 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1925 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1926 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1927 options.kbd_interactive_devices : "")) != 0 || 1928 (r = sshpkt_send(ssh)) != 0) 1929 fatal_fr(r, "send packet"); 1930 1931 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1932 return 1; 1933 } 1934 1935 /* 1936 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1937 */ 1938 static int 1939 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1940 { 1941 Authctxt *authctxt = ssh->authctxt; 1942 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1943 char *display_prompt = NULL, *response = NULL; 1944 u_char echo = 0; 1945 u_int num_prompts, i; 1946 int r; 1947 1948 debug2_f("entering"); 1949 1950 if (authctxt == NULL) 1951 fatal_f("no authentication context"); 1952 1953 authctxt->info_req_seen = 1; 1954 1955 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1956 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1957 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1958 goto out; 1959 if (strlen(name) > 0) 1960 logit("%s", name); 1961 if (strlen(inst) > 0) 1962 logit("%s", inst); 1963 1964 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1965 goto out; 1966 /* 1967 * Begin to build info response packet based on prompts requested. 1968 * We commit to providing the correct number of responses, so if 1969 * further on we run into a problem that prevents this, we have to 1970 * be sure and clean this up and send a correct error response. 1971 */ 1972 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1973 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1974 goto out; 1975 1976 debug2_f("num_prompts %d", num_prompts); 1977 for (i = 0; i < num_prompts; i++) { 1978 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1979 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1980 goto out; 1981 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1982 authctxt->server_user, options.host_key_alias ? 1983 options.host_key_alias : authctxt->host, prompt) == -1) 1984 fatal_f("asmprintf failed"); 1985 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1986 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1987 goto out; 1988 freezero(response, strlen(response)); 1989 free(prompt); 1990 free(display_prompt); 1991 display_prompt = response = prompt = NULL; 1992 } 1993 /* done with parsing incoming message. */ 1994 if ((r = sshpkt_get_end(ssh)) != 0 || 1995 (r = sshpkt_add_padding(ssh, 64)) != 0) 1996 goto out; 1997 r = sshpkt_send(ssh); 1998 out: 1999 if (response) 2000 freezero(response, strlen(response)); 2001 free(prompt); 2002 free(display_prompt); 2003 free(name); 2004 free(inst); 2005 free(lang); 2006 return r; 2007 } 2008 2009 static int 2010 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2011 const u_char *data, size_t datalen) 2012 { 2013 struct sshbuf *b; 2014 struct stat st; 2015 pid_t pid; 2016 int r, to[2], from[2], status; 2017 int sock = ssh_packet_get_connection_in(ssh); 2018 u_char rversion = 0, version = 2; 2019 void (*osigchld)(int); 2020 2021 *sigp = NULL; 2022 *lenp = 0; 2023 2024 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2025 error_f("not installed: %s", strerror(errno)); 2026 return -1; 2027 } 2028 if (fflush(stdout) != 0) { 2029 error_f("fflush: %s", strerror(errno)); 2030 return -1; 2031 } 2032 if (pipe(to) == -1) { 2033 error_f("pipe: %s", strerror(errno)); 2034 return -1; 2035 } 2036 if (pipe(from) == -1) { 2037 error_f("pipe: %s", strerror(errno)); 2038 return -1; 2039 } 2040 if ((pid = fork()) == -1) { 2041 error_f("fork: %s", strerror(errno)); 2042 return -1; 2043 } 2044 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2045 if (pid == 0) { 2046 close(from[0]); 2047 if (dup2(from[1], STDOUT_FILENO) == -1) 2048 fatal_f("dup2: %s", strerror(errno)); 2049 close(to[1]); 2050 if (dup2(to[0], STDIN_FILENO) == -1) 2051 fatal_f("dup2: %s", strerror(errno)); 2052 close(from[1]); 2053 close(to[0]); 2054 2055 if (dup2(sock, STDERR_FILENO + 1) == -1) 2056 fatal_f("dup2: %s", strerror(errno)); 2057 sock = STDERR_FILENO + 1; 2058 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2059 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2060 closefrom(sock + 1); 2061 2062 debug3_f("[child] pid=%ld, exec %s", 2063 (long)getpid(), _PATH_SSH_KEY_SIGN); 2064 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2065 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2066 strerror(errno)); 2067 } 2068 close(from[1]); 2069 close(to[0]); 2070 sock = STDERR_FILENO + 1; 2071 2072 if ((b = sshbuf_new()) == NULL) 2073 fatal_f("sshbuf_new failed"); 2074 /* send # of sock, data to be signed */ 2075 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2076 (r = sshbuf_put_string(b, data, datalen)) != 0) 2077 fatal_fr(r, "buffer error"); 2078 if (ssh_msg_send(to[1], version, b) == -1) 2079 fatal_f("couldn't send request"); 2080 sshbuf_reset(b); 2081 r = ssh_msg_recv(from[0], b); 2082 close(from[0]); 2083 close(to[1]); 2084 if (r < 0) { 2085 error_f("no reply"); 2086 goto fail; 2087 } 2088 2089 errno = 0; 2090 while (waitpid(pid, &status, 0) == -1) { 2091 if (errno != EINTR) { 2092 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2093 goto fail; 2094 } 2095 } 2096 if (!WIFEXITED(status)) { 2097 error_f("exited abnormally"); 2098 goto fail; 2099 } 2100 if (WEXITSTATUS(status) != 0) { 2101 error_f("exited with status %d", WEXITSTATUS(status)); 2102 goto fail; 2103 } 2104 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2105 error_fr(r, "buffer error"); 2106 goto fail; 2107 } 2108 if (rversion != version) { 2109 error_f("bad version"); 2110 goto fail; 2111 } 2112 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2113 error_fr(r, "buffer error"); 2114 fail: 2115 ssh_signal(SIGCHLD, osigchld); 2116 sshbuf_free(b); 2117 return -1; 2118 } 2119 ssh_signal(SIGCHLD, osigchld); 2120 sshbuf_free(b); 2121 2122 return 0; 2123 } 2124 2125 static int 2126 userauth_hostbased(struct ssh *ssh) 2127 { 2128 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2129 struct sshkey *private = NULL; 2130 struct sshbuf *b = NULL; 2131 u_char *sig = NULL, *keyblob = NULL; 2132 char *fp = NULL, *chost = NULL, *lname = NULL; 2133 size_t siglen = 0, keylen = 0; 2134 int i, r, success = 0; 2135 2136 if (authctxt->ktypes == NULL) { 2137 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2138 authctxt->ktypes = authctxt->oktypes; 2139 } 2140 2141 /* 2142 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2143 * trying each hostkey that matches the type in turn. 2144 */ 2145 for (;;) { 2146 if (authctxt->active_ktype == NULL) 2147 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2148 if (authctxt->active_ktype == NULL || 2149 *authctxt->active_ktype == '\0') 2150 break; 2151 debug3_f("trying key type %s", authctxt->active_ktype); 2152 2153 /* check for a useful key */ 2154 private = NULL; 2155 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2156 if (authctxt->sensitive->keys[i] == NULL || 2157 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2158 continue; 2159 if (!sshkey_match_keyname_to_sigalgs( 2160 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2161 authctxt->active_ktype)) 2162 continue; 2163 /* we take and free the key */ 2164 private = authctxt->sensitive->keys[i]; 2165 authctxt->sensitive->keys[i] = NULL; 2166 break; 2167 } 2168 /* Found one */ 2169 if (private != NULL) 2170 break; 2171 /* No more keys of this type; advance */ 2172 authctxt->active_ktype = NULL; 2173 } 2174 if (private == NULL) { 2175 free(authctxt->oktypes); 2176 authctxt->oktypes = authctxt->ktypes = NULL; 2177 authctxt->active_ktype = NULL; 2178 debug("No more client hostkeys for hostbased authentication."); 2179 goto out; 2180 } 2181 2182 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2183 SSH_FP_DEFAULT)) == NULL) { 2184 error_f("sshkey_fingerprint failed"); 2185 goto out; 2186 } 2187 debug_f("trying hostkey %s %s using sigalg %s", 2188 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2189 2190 /* figure out a name for the client host */ 2191 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2192 if (lname == NULL) { 2193 error_f("cannot get local ipaddr/name"); 2194 goto out; 2195 } 2196 2197 /* XXX sshbuf_put_stringf? */ 2198 xasprintf(&chost, "%s.", lname); 2199 debug2_f("chost %s", chost); 2200 2201 /* construct data */ 2202 if ((b = sshbuf_new()) == NULL) { 2203 error_f("sshbuf_new failed"); 2204 goto out; 2205 } 2206 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2207 error_fr(r, "sshkey_to_blob"); 2208 goto out; 2209 } 2210 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2211 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2212 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2213 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2214 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2215 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2216 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2217 (r = sshbuf_put_cstring(b, chost)) != 0 || 2218 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2219 error_fr(r, "buffer error"); 2220 goto out; 2221 } 2222 2223 #ifdef DEBUG_PK 2224 sshbuf_dump(b, stderr); 2225 #endif 2226 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2227 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2228 error("sign using hostkey %s %s failed", 2229 sshkey_ssh_name(private), fp); 2230 goto out; 2231 } 2232 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2233 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2234 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2235 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2236 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2237 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2238 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2239 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2240 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2241 (r = sshpkt_send(ssh)) != 0) { 2242 error_fr(r, "packet error"); 2243 goto out; 2244 } 2245 success = 1; 2246 2247 out: 2248 if (sig != NULL) 2249 freezero(sig, siglen); 2250 free(keyblob); 2251 free(lname); 2252 free(fp); 2253 free(chost); 2254 sshkey_free(private); 2255 sshbuf_free(b); 2256 2257 return success; 2258 } 2259 2260 /* find auth method */ 2261 2262 /* 2263 * given auth method name, if configurable options permit this method fill 2264 * in auth_ident field and return true, otherwise return false. 2265 */ 2266 static int 2267 authmethod_is_enabled(Authmethod *method) 2268 { 2269 if (method == NULL) 2270 return 0; 2271 /* return false if options indicate this method is disabled */ 2272 if (method->enabled == NULL || *method->enabled == 0) 2273 return 0; 2274 /* return false if batch mode is enabled but method needs interactive mode */ 2275 if (method->batch_flag != NULL && *method->batch_flag != 0) 2276 return 0; 2277 return 1; 2278 } 2279 2280 static Authmethod * 2281 authmethod_lookup(const char *name) 2282 { 2283 Authmethod *method = NULL; 2284 if (name != NULL) 2285 for (method = authmethods; method->name != NULL; method++) 2286 if (strcmp(name, method->name) == 0) 2287 return method; 2288 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2289 return NULL; 2290 } 2291 2292 /* XXX internal state */ 2293 static Authmethod *current = NULL; 2294 static char *supported = NULL; 2295 static char *preferred = NULL; 2296 2297 /* 2298 * Given the authentication method list sent by the server, return the 2299 * next method we should try. If the server initially sends a nil list, 2300 * use a built-in default list. 2301 */ 2302 static Authmethod * 2303 authmethod_get(char *authlist) 2304 { 2305 char *name = NULL; 2306 u_int next; 2307 2308 /* Use a suitable default if we're passed a nil list. */ 2309 if (authlist == NULL || strlen(authlist) == 0) 2310 authlist = options.preferred_authentications; 2311 2312 if (supported == NULL || strcmp(authlist, supported) != 0) { 2313 debug3("start over, passed a different list %s", authlist); 2314 free(supported); 2315 supported = xstrdup(authlist); 2316 preferred = options.preferred_authentications; 2317 debug3("preferred %s", preferred); 2318 current = NULL; 2319 } else if (current != NULL && authmethod_is_enabled(current)) 2320 return current; 2321 2322 for (;;) { 2323 if ((name = match_list(preferred, supported, &next)) == NULL) { 2324 debug("No more authentication methods to try."); 2325 current = NULL; 2326 return NULL; 2327 } 2328 preferred += next; 2329 debug3("authmethod_lookup %s", name); 2330 debug3("remaining preferred: %s", preferred); 2331 if ((current = authmethod_lookup(name)) != NULL && 2332 authmethod_is_enabled(current)) { 2333 debug3("authmethod_is_enabled %s", name); 2334 debug("Next authentication method: %s", name); 2335 free(name); 2336 return current; 2337 } 2338 free(name); 2339 } 2340 } 2341 2342 static char * 2343 authmethods_get(void) 2344 { 2345 Authmethod *method = NULL; 2346 struct sshbuf *b; 2347 char *list; 2348 int r; 2349 2350 if ((b = sshbuf_new()) == NULL) 2351 fatal_f("sshbuf_new failed"); 2352 for (method = authmethods; method->name != NULL; method++) { 2353 if (authmethod_is_enabled(method)) { 2354 if ((r = sshbuf_putf(b, "%s%s", 2355 sshbuf_len(b) ? "," : "", method->name)) != 0) 2356 fatal_fr(r, "buffer error"); 2357 } 2358 } 2359 if ((list = sshbuf_dup_string(b)) == NULL) 2360 fatal_f("sshbuf_dup_string failed"); 2361 sshbuf_free(b); 2362 return list; 2363 } 2364