1 /* $OpenBSD: sshconnect2.c,v 1.385 2026/04/02 07:48:13 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 "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/queue.h> 33 #include <sys/stat.h> 34 35 #include <errno.h> 36 #include <fcntl.h> 37 #include <limits.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 "xmalloc.h" 49 #include "ssh.h" 50 #include "ssh2.h" 51 #include "sshbuf.h" 52 #include "packet.h" 53 #include "compat.h" 54 #include "cipher.h" 55 #include "sshkey.h" 56 #include "kex.h" 57 #include "sshconnect.h" 58 #include "authfile.h" 59 #include "authfd.h" 60 #include "log.h" 61 #include "misc.h" 62 #include "readconf.h" 63 #include "match.h" 64 #include "dispatch.h" 65 #include "canohost.h" 66 #include "msg.h" 67 #include "pathnames.h" 68 #include "hostfile.h" 69 #include "ssherr.h" 70 #include "utf8.h" 71 #include "ssh-sk.h" 72 #include "sk-api.h" 73 74 #ifdef GSSAPI 75 #include "ssh-gss.h" 76 #endif 77 78 /* import */ 79 extern Options options; 80 81 /* 82 * SSH2 key exchange 83 */ 84 85 static char *xxx_host; 86 static struct sockaddr *xxx_hostaddr; 87 static const struct ssh_conn_info *xxx_conn_info; 88 static int key_type_allowed(struct sshkey *, const char *); 89 90 static int 91 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 92 { 93 int r; 94 95 if ((r = sshkey_check_rsa_length(hostkey, 96 options.required_rsa_size)) != 0) 97 fatal_r(r, "Bad server host key"); 98 if (!key_type_allowed(hostkey, options.hostkeyalgorithms)) { 99 fatal("Server host key %s not in HostKeyAlgorithms", 100 sshkey_ssh_name(hostkey)); 101 } 102 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 103 xxx_conn_info) != 0) 104 fatal("Host key verification failed."); 105 return 0; 106 } 107 108 /* Returns the first item from a comma-separated algorithm list */ 109 static char * 110 first_alg(const char *algs) 111 { 112 char *ret, *cp; 113 114 ret = xstrdup(algs); 115 if ((cp = strchr(ret, ',')) != NULL) 116 *cp = '\0'; 117 return ret; 118 } 119 120 static char * 121 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 122 const struct ssh_conn_info *cinfo) 123 { 124 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 125 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 126 size_t maxlen; 127 struct hostkeys *hostkeys = NULL; 128 int ktype; 129 u_int i; 130 131 /* Find all hostkeys for this hostname */ 132 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 133 hostkeys = init_hostkeys(); 134 for (i = 0; i < options.num_user_hostfiles; i++) 135 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 136 for (i = 0; i < options.num_system_hostfiles; i++) { 137 load_hostkeys(hostkeys, hostname, 138 options.system_hostfiles[i], 0); 139 } 140 if (options.known_hosts_command != NULL) { 141 load_hostkeys_command(hostkeys, options.known_hosts_command, 142 "ORDER", cinfo, NULL, hostname); 143 } 144 /* 145 * If a plain public key exists that matches the type of the best 146 * preference HostkeyAlgorithms, then use the whole list as is. 147 * Note that we ignore whether the best preference algorithm is a 148 * certificate type, as sshconnect.c will downgrade certs to 149 * plain keys if necessary. 150 */ 151 best = first_alg(options.hostkeyalgorithms); 152 if (lookup_key_in_hostkeys_by_type(hostkeys, 153 sshkey_type_plain(sshkey_type_from_name(best)), 154 sshkey_ecdsa_nid_from_name(best), NULL)) { 155 debug3_f("have matching best-preference key type %s, " 156 "using HostkeyAlgorithms verbatim", best); 157 ret = xstrdup(options.hostkeyalgorithms); 158 goto out; 159 } 160 161 /* 162 * Otherwise, prefer the host key algorithms that match known keys 163 * while keeping the ordering of HostkeyAlgorithms as much as possible. 164 */ 165 oavail = avail = xstrdup(options.hostkeyalgorithms); 166 maxlen = strlen(avail) + 1; 167 first = xmalloc(maxlen); 168 last = xmalloc(maxlen); 169 *first = *last = '\0'; 170 171 #define ALG_APPEND(to, from) \ 172 do { \ 173 if (*to != '\0') \ 174 strlcat(to, ",", maxlen); \ 175 strlcat(to, from, maxlen); \ 176 } while (0) 177 178 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 179 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 180 fatal_f("unknown alg %s", alg); 181 /* 182 * If we have a @cert-authority marker in known_hosts then 183 * prefer all certificate algorithms. 184 */ 185 if (sshkey_type_is_cert(ktype) && 186 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 187 ALG_APPEND(first, alg); 188 continue; 189 } 190 /* If the key appears in known_hosts then prefer it */ 191 if (lookup_key_in_hostkeys_by_type(hostkeys, 192 sshkey_type_plain(ktype), 193 sshkey_ecdsa_nid_from_name(alg), NULL)) { 194 ALG_APPEND(first, alg); 195 continue; 196 } 197 /* Otherwise, put it last */ 198 ALG_APPEND(last, alg); 199 } 200 #undef ALG_APPEND 201 xasprintf(&ret, "%s%s%s", first, 202 (*first == '\0' || *last == '\0') ? "" : ",", last); 203 if (*first != '\0') 204 debug3_f("prefer hostkeyalgs: %s", first); 205 else 206 debug3_f("no algorithms matched; accept original"); 207 out: 208 free(best); 209 free(first); 210 free(last); 211 free(hostname); 212 free(oavail); 213 free_hostkeys(hostkeys); 214 215 return ret; 216 } 217 218 void 219 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 220 const struct ssh_conn_info *cinfo) 221 { 222 char *myproposal[PROPOSAL_MAX]; 223 char *all_key, *hkalgs = NULL; 224 int r, use_known_hosts_order = 0; 225 226 xxx_host = host; 227 xxx_hostaddr = hostaddr; 228 xxx_conn_info = cinfo; 229 230 if (options.rekey_limit || options.rekey_interval) 231 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 232 options.rekey_interval); 233 234 /* 235 * If the user has not specified HostkeyAlgorithms, or has only 236 * appended or removed algorithms from that list then prefer algorithms 237 * that are in the list that are supported by known_hosts keys. 238 */ 239 if (options.hostkeyalgorithms == NULL || 240 options.hostkeyalgorithms[0] == '-' || 241 options.hostkeyalgorithms[0] == '+') 242 use_known_hosts_order = 1; 243 244 /* Expand or fill in HostkeyAlgorithms */ 245 all_key = sshkey_alg_list(0, 0, 1, ','); 246 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 247 kex_default_pk_alg(), all_key)) != 0) 248 fatal_fr(r, "kex_assemble_namelist"); 249 free(all_key); 250 251 if (use_known_hosts_order) 252 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 253 254 kex_proposal_populate_entries(ssh, myproposal, 255 options.kex_algorithms, options.ciphers, options.macs, 256 compression_alg_list(options.compression), 257 hkalgs ? hkalgs : options.hostkeyalgorithms); 258 259 free(hkalgs); 260 261 /* start key exchange */ 262 if ((r = kex_setup(ssh, myproposal)) != 0) 263 fatal_r(r, "kex_setup"); 264 #ifdef WITH_OPENSSL 265 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 266 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 267 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 270 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 271 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 272 # ifdef OPENSSL_HAS_ECC 273 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 274 # endif 275 #endif 276 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 277 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 278 ssh->kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_client; 279 ssh->kex->verify_host_key=&verify_host_key_callback; 280 281 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 282 kex_proposal_free_entries(myproposal); 283 284 #ifdef DEBUG_KEXDH 285 /* send 1st encrypted/maced/compressed message */ 286 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 287 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 288 (r = sshpkt_send(ssh)) != 0 || 289 (r = ssh_packet_write_wait(ssh)) != 0) 290 fatal_fr(r, "send packet"); 291 #endif 292 } 293 294 /* 295 * Authenticate user 296 */ 297 298 typedef struct cauthctxt Authctxt; 299 typedef struct cauthmethod Authmethod; 300 typedef struct identity Identity; 301 typedef struct idlist Idlist; 302 303 struct identity { 304 TAILQ_ENTRY(identity) next; 305 int agent_fd; /* >=0 if agent supports key */ 306 struct sshkey *key; /* public/private key */ 307 char *filename; /* comment for agent-only keys */ 308 int tried; 309 int isprivate; /* key points to the private key */ 310 int userprovided; 311 }; 312 TAILQ_HEAD(idlist, identity); 313 314 struct cauthctxt { 315 const char *server_user; 316 const char *local_user; 317 const char *host; 318 const char *service; 319 struct cauthmethod *method; 320 sig_atomic_t success; 321 char *authlist; 322 #ifdef GSSAPI 323 /* gssapi */ 324 gss_OID_set gss_supported_mechs; 325 u_int mech_tried; 326 #endif 327 /* pubkey */ 328 struct idlist keys; 329 int agent_fd; 330 /* hostbased */ 331 Sensitive *sensitive; 332 char *oktypes, *ktypes; 333 const char *active_ktype; 334 /* kbd-interactive */ 335 int info_req_seen; 336 int attempt_kbdint; 337 /* password */ 338 int attempt_passwd; 339 /* generic */ 340 void *methoddata; 341 }; 342 343 struct cauthmethod { 344 char *name; /* string to compare against server's list */ 345 int (*userauth)(struct ssh *ssh); 346 void (*cleanup)(struct ssh *ssh); 347 int *enabled; /* flag in option struct that enables method */ 348 int *batch_flag; /* flag in option struct that disables method */ 349 }; 350 351 static int input_userauth_service_accept(int, uint32_t, struct ssh *); 352 static int input_userauth_success(int, uint32_t, struct ssh *); 353 static int input_userauth_failure(int, uint32_t, struct ssh *); 354 static int input_userauth_banner(int, uint32_t, struct ssh *); 355 static int input_userauth_error(int, uint32_t, struct ssh *); 356 static int input_userauth_info_req(int, uint32_t, struct ssh *); 357 static int input_userauth_pk_ok(int, uint32_t, struct ssh *); 358 static int input_userauth_passwd_changereq(int, uint32_t, struct ssh *); 359 360 static int userauth_none(struct ssh *); 361 static int userauth_pubkey(struct ssh *); 362 static int userauth_passwd(struct ssh *); 363 static int userauth_kbdint(struct ssh *); 364 static int userauth_hostbased(struct ssh *); 365 366 #ifdef GSSAPI 367 static int userauth_gssapi(struct ssh *); 368 static void userauth_gssapi_cleanup(struct ssh *); 369 static int input_gssapi_response(int type, uint32_t, struct ssh *); 370 static int input_gssapi_token(int type, uint32_t, struct ssh *); 371 static int input_gssapi_error(int, uint32_t, struct ssh *); 372 static int input_gssapi_errtok(int, uint32_t, struct ssh *); 373 #endif 374 375 void userauth(struct ssh *, char *); 376 377 static void pubkey_cleanup(struct ssh *); 378 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 379 static void pubkey_prepare(struct ssh *, Authctxt *); 380 static void pubkey_reset(Authctxt *); 381 static struct sshkey *load_identity_file(Identity *); 382 383 static Authmethod *authmethod_get(char *authlist); 384 static Authmethod *authmethod_lookup(const char *name); 385 static char *authmethods_get(void); 386 387 Authmethod authmethods[] = { 388 #ifdef GSSAPI 389 {"gssapi-with-mic", 390 userauth_gssapi, 391 userauth_gssapi_cleanup, 392 &options.gss_authentication, 393 NULL}, 394 #endif 395 {"hostbased", 396 userauth_hostbased, 397 NULL, 398 &options.hostbased_authentication, 399 NULL}, 400 {"publickey", 401 userauth_pubkey, 402 NULL, 403 &options.pubkey_authentication, 404 NULL}, 405 {"keyboard-interactive", 406 userauth_kbdint, 407 NULL, 408 &options.kbd_interactive_authentication, 409 &options.batch_mode}, 410 {"password", 411 userauth_passwd, 412 NULL, 413 &options.password_authentication, 414 &options.batch_mode}, 415 {"none", 416 userauth_none, 417 NULL, 418 NULL, 419 NULL}, 420 {NULL, NULL, NULL, NULL, NULL} 421 }; 422 423 void 424 ssh_userauth2(struct ssh *ssh, const char *local_user, 425 const char *server_user, char *host, Sensitive *sensitive) 426 { 427 Authctxt authctxt; 428 int r; 429 430 if (options.preferred_authentications == NULL) 431 options.preferred_authentications = authmethods_get(); 432 433 /* setup authentication context */ 434 memset(&authctxt, 0, sizeof(authctxt)); 435 authctxt.server_user = server_user; 436 authctxt.local_user = local_user; 437 authctxt.host = host; 438 authctxt.service = "ssh-connection"; /* service name */ 439 authctxt.success = 0; 440 authctxt.method = authmethod_lookup("none"); 441 authctxt.authlist = NULL; 442 authctxt.methoddata = NULL; 443 authctxt.sensitive = sensitive; 444 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 445 authctxt.info_req_seen = 0; 446 authctxt.attempt_kbdint = 0; 447 authctxt.attempt_passwd = 0; 448 #if GSSAPI 449 authctxt.gss_supported_mechs = NULL; 450 authctxt.mech_tried = 0; 451 #endif 452 authctxt.agent_fd = -1; 453 if (authctxt.method == NULL) 454 fatal_f("internal error: cannot send userauth none request"); 455 456 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 457 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 458 (r = sshpkt_send(ssh)) != 0) 459 fatal_fr(r, "send packet"); 460 461 ssh->authctxt = &authctxt; 462 ssh_dispatch_init(ssh, &input_userauth_error); 463 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 464 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 465 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 466 pubkey_cleanup(ssh); 467 #ifdef GSSAPI 468 if (authctxt.gss_supported_mechs != NULL) { 469 u_int ms; 470 471 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 472 authctxt.gss_supported_mechs = NULL; 473 } 474 #endif 475 ssh->authctxt = NULL; 476 477 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 478 479 if (!authctxt.success) 480 fatal("Authentication failed."); 481 if (ssh_packet_connection_is_on_socket(ssh)) { 482 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 484 authctxt.method->name); 485 } else { 486 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 487 authctxt.method->name); 488 } 489 } 490 491 static int 492 input_userauth_service_accept(int type, uint32_t seq, struct ssh *ssh) 493 { 494 int r; 495 496 if (ssh_packet_remaining(ssh) > 0) { 497 char *reply; 498 499 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 500 goto out; 501 debug2("service_accept: %s", reply); 502 free(reply); 503 } else { 504 debug2("buggy server: service_accept w/o service"); 505 } 506 if ((r = sshpkt_get_end(ssh)) != 0) 507 goto out; 508 debug("SSH2_MSG_SERVICE_ACCEPT received"); 509 510 /* initial userauth request */ 511 userauth_none(ssh); 512 513 /* accept EXT_INFO at any time during userauth */ 514 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 515 &kex_input_ext_info : &input_userauth_error); 516 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 517 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 519 r = 0; 520 out: 521 return r; 522 } 523 524 void 525 userauth(struct ssh *ssh, char *authlist) 526 { 527 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 528 529 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 530 authctxt->method->cleanup(ssh); 531 532 free(authctxt->methoddata); 533 authctxt->methoddata = NULL; 534 if (authlist == NULL) { 535 authlist = authctxt->authlist; 536 } else { 537 free(authctxt->authlist); 538 authctxt->authlist = authlist; 539 } 540 for (;;) { 541 Authmethod *method = authmethod_get(authlist); 542 if (method == NULL) 543 fatal("%s@%s: Permission denied (%s).", 544 authctxt->server_user, authctxt->host, authlist); 545 authctxt->method = method; 546 547 /* reset the per method handler */ 548 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 549 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 550 551 /* and try new method */ 552 if (method->userauth(ssh) != 0) { 553 debug2("we sent a %s packet, wait for reply", method->name); 554 break; 555 } else { 556 debug2("we did not send a packet, disable method"); 557 method->enabled = NULL; 558 } 559 } 560 } 561 562 static int 563 input_userauth_error(int type, uint32_t seq, struct ssh *ssh) 564 { 565 fatal_f("bad message during authentication: type %d", type); 566 return 0; 567 } 568 569 static int 570 input_userauth_banner(int type, uint32_t seq, struct ssh *ssh) 571 { 572 char *msg = NULL; 573 size_t len; 574 int r; 575 576 debug3_f("entering"); 577 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 578 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 579 goto out; 580 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 581 fmprintf(stderr, "%s", msg); 582 r = 0; 583 out: 584 free(msg); 585 return r; 586 } 587 588 static int 589 input_userauth_success(int type, uint32_t seq, struct ssh *ssh) 590 { 591 Authctxt *authctxt = ssh->authctxt; 592 593 if (authctxt == NULL) 594 fatal_f("no authentication context"); 595 free(authctxt->authlist); 596 authctxt->authlist = NULL; 597 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 598 authctxt->method->cleanup(ssh); 599 free(authctxt->methoddata); 600 authctxt->methoddata = NULL; 601 authctxt->success = 1; /* break out */ 602 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 603 return 0; 604 } 605 606 #if 0 607 static int 608 input_userauth_success_unexpected(int type, uint32_t seq, struct ssh *ssh) 609 { 610 Authctxt *authctxt = ssh->authctxt; 611 612 if (authctxt == NULL) 613 fatal_f("no authentication context"); 614 615 fatal("Unexpected authentication success during %s.", 616 authctxt->method->name); 617 return 0; 618 } 619 #endif 620 621 static int 622 input_userauth_failure(int type, uint32_t seq, struct ssh *ssh) 623 { 624 Authctxt *authctxt = ssh->authctxt; 625 char *authlist = NULL; 626 u_char partial; 627 628 if (authctxt == NULL) 629 fatal("input_userauth_failure: no authentication context"); 630 631 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 632 sshpkt_get_u8(ssh, &partial) != 0 || 633 sshpkt_get_end(ssh) != 0) 634 goto out; 635 636 if (partial != 0) { 637 verbose("Authenticated using \"%s\" with partial success.", 638 authctxt->method->name); 639 /* reset state */ 640 pubkey_reset(authctxt); 641 } 642 debug("Authentications that can continue: %s", authlist); 643 644 userauth(ssh, authlist); 645 authlist = NULL; 646 out: 647 free(authlist); 648 return 0; 649 } 650 651 /* 652 * Format an identity for logging including filename, key type, fingerprint 653 * and location (agent, etc.). Caller must free. 654 */ 655 static char * 656 format_identity(Identity *id) 657 { 658 char *fp = NULL, *ret = NULL; 659 const char *note = ""; 660 661 if (id->key != NULL) { 662 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 663 SSH_FP_DEFAULT); 664 } 665 if (id->key) { 666 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 667 note = " token"; 668 else if (sshkey_is_sk(id->key)) 669 note = " authenticator"; 670 } 671 xasprintf(&ret, "%s %s%s%s%s%s%s", 672 id->filename, 673 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 674 fp ? fp : "", 675 id->userprovided ? " explicit" : "", note, 676 id->agent_fd != -1 ? " agent" : ""); 677 free(fp); 678 return ret; 679 } 680 681 static int 682 input_userauth_pk_ok(int type, uint32_t seq, struct ssh *ssh) 683 { 684 Authctxt *authctxt = ssh->authctxt; 685 struct sshkey *key = NULL; 686 Identity *id = NULL; 687 int pktype, found = 0, sent = 0; 688 size_t blen; 689 char *pkalg = NULL, *fp = NULL, *ident = NULL; 690 u_char *pkblob = NULL; 691 int r; 692 693 if (authctxt == NULL) 694 fatal("input_userauth_pk_ok: no authentication context"); 695 696 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 697 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 698 (r = sshpkt_get_end(ssh)) != 0) 699 goto done; 700 701 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 702 debug_f("server sent unknown pkalg %s", pkalg); 703 r = SSH_ERR_INVALID_FORMAT; 704 goto done; 705 } 706 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 707 debug_r(r, "no key from blob. pkalg %s", pkalg); 708 goto done; 709 } 710 if (key->type != pktype) { 711 error("input_userauth_pk_ok: type mismatch " 712 "for decoded key (received %d, expected %d)", 713 key->type, pktype); 714 r = SSH_ERR_INVALID_FORMAT; 715 goto done; 716 } 717 718 /* 719 * search keys in the reverse order, because last candidate has been 720 * moved to the end of the queue. this also avoids confusion by 721 * duplicate keys 722 */ 723 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 724 if (sshkey_equal(key, id->key)) { 725 found = 1; 726 break; 727 } 728 } 729 if (!found || id == NULL) { 730 fp = sshkey_fingerprint(key, options.fingerprint_hash, 731 SSH_FP_DEFAULT); 732 error_f("server replied with unknown key: %s %s", 733 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 734 r = SSH_ERR_INVALID_FORMAT; 735 goto done; 736 } 737 ident = format_identity(id); 738 debug("Server accepts key: %s", ident); 739 sent = sign_and_send_pubkey(ssh, id); 740 r = 0; 741 done: 742 sshkey_free(key); 743 free(ident); 744 free(fp); 745 free(pkalg); 746 free(pkblob); 747 748 /* try another method if we did not send a packet */ 749 if (r == 0 && sent == 0) 750 userauth(ssh, NULL); 751 return r; 752 } 753 754 #ifdef GSSAPI 755 static int 756 userauth_gssapi(struct ssh *ssh) 757 { 758 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 759 Gssctxt *gssctxt = NULL; 760 OM_uint32 min; 761 int r, ok = 0; 762 gss_OID mech = NULL; 763 764 /* Try one GSSAPI method at a time, rather than sending them all at 765 * once. */ 766 767 if (authctxt->gss_supported_mechs == NULL) 768 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 769 770 /* Check to see whether the mechanism is usable before we offer it */ 771 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 772 !ok) { 773 mech = &authctxt->gss_supported_mechs-> 774 elements[authctxt->mech_tried]; 775 /* My DER encoding requires length<128 */ 776 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 777 mech, authctxt->host)) { 778 ok = 1; /* Mechanism works */ 779 } else { 780 authctxt->mech_tried++; 781 } 782 } 783 784 if (!ok || mech == NULL) 785 return 0; 786 787 authctxt->methoddata=(void *)gssctxt; 788 789 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 790 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 791 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 792 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 793 (r = sshpkt_put_u32(ssh, 1)) != 0 || 794 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 795 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 796 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 797 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 798 (r = sshpkt_send(ssh)) != 0) 799 fatal_fr(r, "send packet"); 800 801 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 802 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 803 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 804 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 805 806 authctxt->mech_tried++; /* Move along to next candidate */ 807 808 return 1; 809 } 810 811 static void 812 userauth_gssapi_cleanup(struct ssh *ssh) 813 { 814 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 815 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 816 817 ssh_gssapi_delete_ctx(&gssctxt); 818 authctxt->methoddata = NULL; 819 } 820 821 static OM_uint32 822 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 823 { 824 Authctxt *authctxt = ssh->authctxt; 825 Gssctxt *gssctxt = authctxt->methoddata; 826 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 827 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 828 gss_buffer_desc gssbuf; 829 OM_uint32 status, ms, flags; 830 int r; 831 832 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 833 recv_tok, &send_tok, &flags); 834 835 if (send_tok.length > 0) { 836 u_char type = GSS_ERROR(status) ? 837 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 838 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 839 840 if ((r = sshpkt_start(ssh, type)) != 0 || 841 (r = sshpkt_put_string(ssh, send_tok.value, 842 send_tok.length)) != 0 || 843 (r = sshpkt_send(ssh)) != 0) 844 fatal_fr(r, "send %u packet", type); 845 846 gss_release_buffer(&ms, &send_tok); 847 } 848 849 if (status == GSS_S_COMPLETE) { 850 /* send either complete or MIC, depending on mechanism */ 851 if (!(flags & GSS_C_INTEG_FLAG)) { 852 if ((r = sshpkt_start(ssh, 853 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 854 (r = sshpkt_send(ssh)) != 0) 855 fatal_fr(r, "send completion"); 856 } else { 857 struct sshbuf *b; 858 859 if ((b = sshbuf_new()) == NULL) 860 fatal_f("sshbuf_new failed"); 861 ssh_gssapi_buildmic(b, authctxt->server_user, 862 authctxt->service, "gssapi-with-mic", 863 ssh->kex->session_id); 864 865 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 866 fatal_f("sshbuf_mutable_ptr failed"); 867 gssbuf.length = sshbuf_len(b); 868 869 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 870 871 if (!GSS_ERROR(status)) { 872 if ((r = sshpkt_start(ssh, 873 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 874 (r = sshpkt_put_string(ssh, mic.value, 875 mic.length)) != 0 || 876 (r = sshpkt_send(ssh)) != 0) 877 fatal_fr(r, "send MIC"); 878 } 879 880 sshbuf_free(b); 881 gss_release_buffer(&ms, &mic); 882 } 883 } 884 885 return status; 886 } 887 888 static int 889 input_gssapi_response(int type, uint32_t plen, struct ssh *ssh) 890 { 891 Authctxt *authctxt = ssh->authctxt; 892 Gssctxt *gssctxt; 893 size_t oidlen; 894 u_char *oidv = NULL; 895 int r; 896 897 if (authctxt == NULL) 898 fatal("input_gssapi_response: no authentication context"); 899 gssctxt = authctxt->methoddata; 900 901 /* Setup our OID */ 902 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 903 goto done; 904 905 if (oidlen <= 2 || 906 oidv[0] != SSH_GSS_OIDTYPE || 907 oidv[1] != oidlen - 2) { 908 debug("Badly encoded mechanism OID received"); 909 userauth(ssh, NULL); 910 goto ok; 911 } 912 913 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 914 fatal("Server returned different OID than expected"); 915 916 if ((r = sshpkt_get_end(ssh)) != 0) 917 goto done; 918 919 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 920 /* Start again with next method on list */ 921 debug("Trying to start again"); 922 userauth(ssh, NULL); 923 goto ok; 924 } 925 ok: 926 r = 0; 927 done: 928 free(oidv); 929 return r; 930 } 931 932 static int 933 input_gssapi_token(int type, uint32_t plen, struct ssh *ssh) 934 { 935 Authctxt *authctxt = ssh->authctxt; 936 gss_buffer_desc recv_tok; 937 u_char *p = NULL; 938 size_t len; 939 OM_uint32 status; 940 int r; 941 942 if (authctxt == NULL) 943 fatal("input_gssapi_response: no authentication context"); 944 945 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 946 (r = sshpkt_get_end(ssh)) != 0) 947 goto out; 948 949 recv_tok.value = p; 950 recv_tok.length = len; 951 status = process_gssapi_token(ssh, &recv_tok); 952 953 /* Start again with the next method in the list */ 954 if (GSS_ERROR(status)) { 955 userauth(ssh, NULL); 956 /* ok */ 957 } 958 r = 0; 959 out: 960 free(p); 961 return r; 962 } 963 964 static int 965 input_gssapi_errtok(int type, uint32_t plen, struct ssh *ssh) 966 { 967 Authctxt *authctxt = ssh->authctxt; 968 Gssctxt *gssctxt; 969 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 970 gss_buffer_desc recv_tok; 971 OM_uint32 ms; 972 u_char *p = NULL; 973 size_t len; 974 int r; 975 976 if (authctxt == NULL) 977 fatal("input_gssapi_response: no authentication context"); 978 gssctxt = authctxt->methoddata; 979 980 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 981 (r = sshpkt_get_end(ssh)) != 0) { 982 free(p); 983 return r; 984 } 985 986 /* Stick it into GSSAPI and see what it says */ 987 recv_tok.value = p; 988 recv_tok.length = len; 989 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 990 &recv_tok, &send_tok, NULL); 991 free(p); 992 gss_release_buffer(&ms, &send_tok); 993 994 /* Server will be returning a failed packet after this one */ 995 return 0; 996 } 997 998 static int 999 input_gssapi_error(int type, uint32_t plen, struct ssh *ssh) 1000 { 1001 char *msg = NULL; 1002 char *lang = NULL; 1003 int r; 1004 1005 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1006 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1007 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1008 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1009 goto out; 1010 r = sshpkt_get_end(ssh); 1011 debug("Server GSSAPI Error:\n%s", msg); 1012 out: 1013 free(msg); 1014 free(lang); 1015 return r; 1016 } 1017 #endif /* GSSAPI */ 1018 1019 static int 1020 userauth_none(struct ssh *ssh) 1021 { 1022 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1023 int r; 1024 1025 /* initial userauth request */ 1026 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1027 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1028 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1029 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1030 (r = sshpkt_send(ssh)) != 0) 1031 fatal_fr(r, "send packet"); 1032 return 1; 1033 } 1034 1035 static int 1036 userauth_passwd(struct ssh *ssh) 1037 { 1038 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1039 char *password, *prompt = NULL; 1040 const char *host = options.host_key_alias ? options.host_key_alias : 1041 authctxt->host; 1042 int r; 1043 1044 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1045 return 0; 1046 1047 if (authctxt->attempt_passwd != 1) 1048 error("Permission denied, please try again."); 1049 1050 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1051 password = read_passphrase(prompt, 0); 1052 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1053 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1056 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1057 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1058 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1059 (r = sshpkt_send(ssh)) != 0) 1060 fatal_fr(r, "send packet"); 1061 1062 free(prompt); 1063 if (password != NULL) 1064 freezero(password, strlen(password)); 1065 1066 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1067 &input_userauth_passwd_changereq); 1068 1069 return 1; 1070 } 1071 1072 /* 1073 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1074 */ 1075 static int 1076 input_userauth_passwd_changereq(int type, uint32_t seqnr, struct ssh *ssh) 1077 { 1078 Authctxt *authctxt = ssh->authctxt; 1079 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1080 char prompt[256]; 1081 const char *host; 1082 int r, addnl; 1083 size_t len; 1084 1085 debug2("input_userauth_passwd_changereq"); 1086 1087 if (authctxt == NULL) 1088 fatal("input_userauth_passwd_changereq: " 1089 "no authentication context"); 1090 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1091 1092 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1093 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1094 goto out; 1095 if ((len = strlen(info)) > 0) { 1096 addnl = info[len] != '\n'; 1097 fmprintf(stderr, "%s%s", info, addnl ? "\n" : ""); 1098 } 1099 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1100 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1101 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1102 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1103 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1104 goto out; 1105 1106 snprintf(prompt, sizeof(prompt), 1107 "Enter %.30s@%.128s's old password: ", 1108 authctxt->server_user, host); 1109 password = read_passphrase(prompt, 0); 1110 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1111 goto out; 1112 1113 freezero(password, strlen(password)); 1114 password = NULL; 1115 while (password == NULL) { 1116 snprintf(prompt, sizeof(prompt), 1117 "Enter %.30s@%.128s's new password: ", 1118 authctxt->server_user, host); 1119 password = read_passphrase(prompt, RP_ALLOW_EOF); 1120 if (password == NULL) { 1121 /* bail out */ 1122 r = 0; 1123 goto out; 1124 } 1125 snprintf(prompt, sizeof(prompt), 1126 "Retype %.30s@%.128s's new password: ", 1127 authctxt->server_user, host); 1128 retype = read_passphrase(prompt, 0); 1129 if (strcmp(password, retype) != 0) { 1130 freezero(password, strlen(password)); 1131 logit("Mismatch; try again, EOF to quit."); 1132 password = NULL; 1133 } 1134 freezero(retype, strlen(retype)); 1135 } 1136 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1137 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1138 (r = sshpkt_send(ssh)) != 0) 1139 goto out; 1140 1141 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1142 &input_userauth_passwd_changereq); 1143 r = 0; 1144 out: 1145 if (password) 1146 freezero(password, strlen(password)); 1147 free(info); 1148 free(lang); 1149 return r; 1150 } 1151 1152 /* 1153 * Select an algorithm for publickey signatures. 1154 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1155 * 1156 * Call with ssh==NULL to ignore server-sig-algs extension list and 1157 * only attempt with the key's base signature type. 1158 */ 1159 static char * 1160 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1161 { 1162 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1163 const char *server_sig_algs; 1164 1165 /* 1166 * The signature algorithm will only differ from the key algorithm 1167 * for RSA keys/certs and when the server advertises support for 1168 * newer (SHA2) algorithms. 1169 */ 1170 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1171 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1172 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1173 /* Filter base key signature alg against our configuration */ 1174 return match_list(sshkey_ssh_name(key), 1175 options.pubkey_accepted_algos, NULL); 1176 } 1177 1178 /* 1179 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1180 * fails to advertise it via SSH2_MSG_EXT_INFO. 1181 */ 1182 server_sig_algs = ssh->kex->server_sig_algs; 1183 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1184 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1185 1186 /* 1187 * For RSA keys/certs, since these might have a different sig type: 1188 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1189 * that also appears in the supported signature algorithms list from 1190 * the server. 1191 */ 1192 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1193 while ((cp = strsep(&allowed, ",")) != NULL) { 1194 if (sshkey_type_from_name(cp) != key->type) 1195 continue; 1196 tmp = match_list(sshkey_sigalg_by_name(cp), 1197 server_sig_algs, NULL); 1198 if (tmp != NULL) 1199 alg = xstrdup(cp); 1200 free(tmp); 1201 if (alg != NULL) 1202 break; 1203 } 1204 free(oallowed); 1205 return alg; 1206 } 1207 1208 static int 1209 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1210 const u_char *data, size_t datalen, u_int compat, const char *alg) 1211 { 1212 struct sshkey *sign_key = NULL, *prv = NULL; 1213 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1214 struct notifier_ctx *notifier = NULL; 1215 char *fp = NULL, *pin = NULL, *prompt = NULL; 1216 1217 *sigp = NULL; 1218 *lenp = 0; 1219 1220 /* The agent supports this key. */ 1221 if (id->key != NULL && id->agent_fd != -1) { 1222 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1223 data, datalen, alg, compat); 1224 } 1225 1226 /* 1227 * We have already loaded the private key or the private key is 1228 * stored in external hardware. 1229 */ 1230 if (id->key != NULL && 1231 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1232 sign_key = id->key; 1233 is_agent = 1; 1234 } else { 1235 /* Load the private key from the file. */ 1236 if ((prv = load_identity_file(id)) == NULL) 1237 return SSH_ERR_KEY_NOT_FOUND; 1238 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1239 error_f("private key %s contents do not match public", 1240 id->filename); 1241 r = SSH_ERR_KEY_NOT_FOUND; 1242 goto out; 1243 } 1244 sign_key = prv; 1245 } 1246 retry_pin: 1247 /* Prompt for touch for non-agent FIDO keys that request UP */ 1248 if (!is_agent && sshkey_is_sk(sign_key) && 1249 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1250 /* XXX should batch mode just skip these? */ 1251 if ((fp = sshkey_fingerprint(sign_key, 1252 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1253 fatal_f("fingerprint failed"); 1254 notifier = notify_start(options.batch_mode, 1255 "Confirm user presence for key %s %s", 1256 sshkey_type(sign_key), fp); 1257 free(fp); 1258 } 1259 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1260 alg, options.sk_provider, pin, compat)) != 0) { 1261 debug_fr(r, "sshkey_sign"); 1262 if (!retried && pin == NULL && !is_agent && 1263 sshkey_is_sk(sign_key) && 1264 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1265 notify_complete(notifier, NULL); 1266 notifier = NULL; 1267 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1268 sshkey_type(sign_key), id->filename); 1269 pin = read_passphrase(prompt, 0); 1270 retried = 1; 1271 goto retry_pin; 1272 } 1273 goto out; 1274 } 1275 1276 /* 1277 * PKCS#11 tokens may not support all signature algorithms, 1278 * so check what we get back. 1279 */ 1280 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0 && 1281 (r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1282 debug_fr(r, "sshkey_check_sigtype"); 1283 goto out; 1284 } 1285 /* success */ 1286 r = 0; 1287 out: 1288 free(prompt); 1289 if (pin != NULL) 1290 freezero(pin, strlen(pin)); 1291 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1292 sshkey_free(prv); 1293 return r; 1294 } 1295 1296 static int 1297 id_filename_matches(Identity *id, Identity *private_id) 1298 { 1299 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1300 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1301 size_t i, slen; 1302 1303 if (strcmp(id->filename, private_id->filename) == 0) 1304 return 1; 1305 for (i = 0; suffixes[i]; i++) { 1306 slen = strlen(suffixes[i]); 1307 if (len > slen && plen == len - slen && 1308 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1309 memcmp(id->filename, private_id->filename, plen) == 0) 1310 return 1; 1311 } 1312 return 0; 1313 } 1314 1315 static int 1316 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1317 { 1318 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1319 struct sshbuf *b = NULL; 1320 Identity *private_id, *sign_id = NULL; 1321 u_char *signature = NULL; 1322 size_t slen = 0, skip = 0; 1323 int r, fallback_sigtype, sent = 0; 1324 char *alg = NULL, *fp = NULL; 1325 const char *loc = "", *method = "publickey"; 1326 int hostbound = 0; 1327 1328 /* prefer host-bound pubkey signatures if supported by server */ 1329 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1330 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1331 hostbound = 1; 1332 method = "publickey-hostbound-v00@openssh.com"; 1333 } 1334 1335 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1336 SSH_FP_DEFAULT)) == NULL) 1337 return 0; 1338 1339 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1340 1341 /* 1342 * If the key is an certificate, try to find a matching private key 1343 * and use it to complete the signature. 1344 * If no such private key exists, fall back to trying the certificate 1345 * key itself in case it has a private half already loaded. 1346 * This will try to set sign_id to the private key that will perform 1347 * the signature. 1348 */ 1349 if (id->agent_fd == -1 && sshkey_is_cert(id->key)) { 1350 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1351 if (sshkey_equal_public(id->key, private_id->key) && 1352 id->key->type != private_id->key->type) { 1353 sign_id = private_id; 1354 break; 1355 } 1356 } 1357 /* 1358 * Exact key matches are preferred, but also allow 1359 * filename matches for non-PKCS#11/agent keys that 1360 * didn't load public keys. This supports the case 1361 * of keeping just a private key file and public 1362 * certificate on disk. 1363 */ 1364 if (sign_id == NULL && 1365 !id->isprivate && id->agent_fd == -1 && 1366 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1367 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1368 if (private_id->key == NULL && 1369 id_filename_matches(id, private_id)) { 1370 sign_id = private_id; 1371 break; 1372 } 1373 } 1374 } 1375 if (sign_id != NULL) { 1376 debug2_f("using private key \"%s\"%s for " 1377 "certificate", sign_id->filename, 1378 sign_id->agent_fd != -1 ? " from agent" : ""); 1379 } else { 1380 debug_f("no separate private key for certificate " 1381 "\"%s\"", id->filename); 1382 } 1383 } 1384 1385 /* 1386 * If the above didn't select another identity to do the signing 1387 * then default to the one we started with. 1388 */ 1389 if (sign_id == NULL) 1390 sign_id = id; 1391 1392 /* assemble and sign data */ 1393 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1394 free(alg); 1395 slen = 0; 1396 signature = NULL; 1397 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1398 id->key)) == NULL) { 1399 error_f("no mutual signature supported"); 1400 goto out; 1401 } 1402 debug3_f("signing using %s %s", alg, fp); 1403 1404 sshbuf_free(b); 1405 if ((b = sshbuf_new()) == NULL) 1406 fatal_f("sshbuf_new failed"); 1407 if (ssh->compat & SSH_OLD_SESSIONID) { 1408 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1409 fatal_fr(r, "sshbuf_putb"); 1410 } else { 1411 if ((r = sshbuf_put_stringb(b, 1412 ssh->kex->session_id)) != 0) 1413 fatal_fr(r, "sshbuf_put_stringb"); 1414 } 1415 skip = sshbuf_len(b); 1416 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1417 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1418 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1419 (r = sshbuf_put_cstring(b, method)) != 0 || 1420 (r = sshbuf_put_u8(b, 1)) != 0 || 1421 (r = sshbuf_put_cstring(b, alg)) != 0 || 1422 (r = sshkey_puts(id->key, b)) != 0) { 1423 fatal_fr(r, "assemble signed data"); 1424 } 1425 if (hostbound) { 1426 if (ssh->kex->initial_hostkey == NULL) { 1427 fatal_f("internal error: initial hostkey " 1428 "not recorded"); 1429 } 1430 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1431 fatal_fr(r, "assemble %s hostkey", method); 1432 } 1433 /* generate signature */ 1434 r = identity_sign(sign_id, &signature, &slen, 1435 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1436 if (r == 0) 1437 break; 1438 else if (r == SSH_ERR_KEY_NOT_FOUND) 1439 goto out; /* soft failure */ 1440 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1441 !fallback_sigtype) { 1442 if (sign_id->agent_fd != -1) 1443 loc = "agent "; 1444 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1445 loc = "token "; 1446 logit("%skey %s %s returned incorrect signature type", 1447 loc, sshkey_type(id->key), fp); 1448 continue; 1449 } 1450 error_fr(r, "signing failed for %s \"%s\"%s", 1451 sshkey_type(sign_id->key), sign_id->filename, 1452 id->agent_fd != -1 ? " from agent" : ""); 1453 goto out; 1454 } 1455 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1456 fatal_f("no signature"); 1457 1458 /* append signature */ 1459 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1460 fatal_fr(r, "append signature"); 1461 1462 #ifdef DEBUG_PK 1463 sshbuf_dump(b, stderr); 1464 #endif 1465 /* skip session id and packet type */ 1466 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1467 fatal_fr(r, "consume"); 1468 1469 /* put remaining data from buffer into packet */ 1470 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1471 (r = sshpkt_putb(ssh, b)) != 0 || 1472 (r = sshpkt_send(ssh)) != 0) 1473 fatal_fr(r, "enqueue request"); 1474 1475 /* success */ 1476 sent = 1; 1477 1478 out: 1479 free(fp); 1480 free(alg); 1481 sshbuf_free(b); 1482 freezero(signature, slen); 1483 return sent; 1484 } 1485 1486 static int 1487 send_pubkey_test(struct ssh *ssh, Identity *id) 1488 { 1489 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1490 u_char *blob = NULL; 1491 char *alg = NULL; 1492 size_t bloblen; 1493 u_int have_sig = 0; 1494 int sent = 0, r; 1495 1496 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1497 debug_f("no mutual signature algorithm"); 1498 goto out; 1499 } 1500 1501 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1502 /* we cannot handle this key */ 1503 debug3_f("cannot handle key"); 1504 goto out; 1505 } 1506 /* register callback for USERAUTH_PK_OK message */ 1507 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1508 1509 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1510 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1511 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1512 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1513 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1514 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1515 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1516 (r = sshpkt_send(ssh)) != 0) 1517 fatal_fr(r, "send packet"); 1518 sent = 1; 1519 1520 out: 1521 free(alg); 1522 free(blob); 1523 return sent; 1524 } 1525 1526 static struct sshkey * 1527 load_identity_file(Identity *id) 1528 { 1529 struct sshkey *private = NULL; 1530 char prompt[300], *passphrase, *comment; 1531 int r, quit = 0, i; 1532 struct stat st; 1533 1534 if (stat(id->filename, &st) == -1) { 1535 do_log2(id->userprovided ? 1536 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1537 "no such identity: %s: %s", id->filename, strerror(errno)); 1538 return NULL; 1539 } 1540 snprintf(prompt, sizeof prompt, 1541 "Enter passphrase for key '%.100s': ", id->filename); 1542 for (i = 0; i <= options.number_of_password_prompts; i++) { 1543 if (i == 0) 1544 passphrase = ""; 1545 else { 1546 passphrase = read_passphrase(prompt, 0); 1547 if (*passphrase == '\0') { 1548 debug2("no passphrase given, try next key"); 1549 free(passphrase); 1550 break; 1551 } 1552 } 1553 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1554 passphrase, &private, &comment))) { 1555 case 0: 1556 break; 1557 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1558 if (options.batch_mode) { 1559 quit = 1; 1560 break; 1561 } 1562 if (i != 0) 1563 debug2("bad passphrase given, try again..."); 1564 break; 1565 case SSH_ERR_SYSTEM_ERROR: 1566 if (errno == ENOENT) { 1567 debug2_r(r, "Load key \"%s\"", id->filename); 1568 quit = 1; 1569 break; 1570 } 1571 /* FALLTHROUGH */ 1572 default: 1573 error_r(r, "Load key \"%s\"", id->filename); 1574 quit = 1; 1575 break; 1576 } 1577 if (private != NULL && sshkey_is_sk(private) && 1578 options.sk_provider == NULL) { 1579 debug("key \"%s\" is an authenticator-hosted key, " 1580 "but no provider specified", id->filename); 1581 sshkey_free(private); 1582 private = NULL; 1583 quit = 1; 1584 } 1585 if (!quit && (r = sshkey_check_rsa_length(private, 1586 options.required_rsa_size)) != 0) { 1587 debug_fr(r, "Skipping key %s", id->filename); 1588 sshkey_free(private); 1589 private = NULL; 1590 quit = 1; 1591 } 1592 if (!quit && private != NULL && id->agent_fd == -1 && 1593 !(id->key && id->isprivate)) 1594 maybe_add_key_to_agent(id->filename, private, comment, 1595 passphrase); 1596 if (i > 0) 1597 freezero(passphrase, strlen(passphrase)); 1598 free(comment); 1599 if (private != NULL || quit) 1600 break; 1601 } 1602 return private; 1603 } 1604 1605 static int 1606 key_type_allowed(struct sshkey *key, const char *allowlist) 1607 { 1608 if (match_pattern_list(sshkey_ssh_name(key), allowlist, 0) == 1) 1609 return 1; 1610 1611 /* RSA keys/certs might be allowed by alternate signature types */ 1612 switch (key->type) { 1613 case KEY_RSA: 1614 if (match_pattern_list("rsa-sha2-512", allowlist, 0) == 1) 1615 return 1; 1616 if (match_pattern_list("rsa-sha2-256", allowlist, 0) == 1) 1617 return 1; 1618 break; 1619 case KEY_RSA_CERT: 1620 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1621 allowlist, 0) == 1) 1622 return 1; 1623 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1624 allowlist, 0) == 1) 1625 return 1; 1626 break; 1627 } 1628 return 0; 1629 } 1630 1631 static int 1632 key_type_allowed_by_config(struct sshkey *key) 1633 { 1634 return key_type_allowed(key, options.pubkey_accepted_algos); 1635 } 1636 1637 /* obtain a list of keys from the agent */ 1638 static int 1639 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1640 struct ssh_identitylist **idlistp) 1641 { 1642 int r, agent_fd; 1643 struct ssh_identitylist *idlist; 1644 1645 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1646 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1647 debug_fr(r, "ssh_get_authentication_socket"); 1648 return r; 1649 } 1650 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1651 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1652 debug_f("bound agent to hostkey"); 1653 else 1654 debug2_fr(r, "ssh_agent_bind_hostkey"); 1655 1656 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1657 debug_fr(r, "ssh_fetch_identitylist"); 1658 close(agent_fd); 1659 return r; 1660 } 1661 /* success */ 1662 *agent_fdp = agent_fd; 1663 *idlistp = idlist; 1664 debug_f("agent returned %zu keys", idlist->nkeys); 1665 return 0; 1666 } 1667 1668 /* 1669 * try keys in the following order: 1670 * 1. certificates listed in the config file 1671 * 2. other input certificates 1672 * 3. agent keys that are found in the config file 1673 * 4. other agent keys 1674 * 5. keys that are only listed in the config file 1675 */ 1676 static void 1677 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1678 { 1679 struct identity *id, *id2, *tmp; 1680 struct idlist agent, files, *preferred; 1681 struct sshkey *key; 1682 int disallowed, agent_fd = -1, i, r, found; 1683 size_t j; 1684 struct ssh_identitylist *idlist; 1685 char *cp, *ident; 1686 1687 TAILQ_INIT(&agent); /* keys from the agent */ 1688 TAILQ_INIT(&files); /* keys from the config file */ 1689 preferred = &authctxt->keys; 1690 TAILQ_INIT(preferred); /* preferred order of keys */ 1691 1692 /* list of keys stored in the filesystem and PKCS#11 */ 1693 for (i = 0; i < options.num_identity_files; i++) { 1694 key = options.identity_keys[i]; 1695 if (key && key->cert && 1696 key->cert->type != SSH2_CERT_TYPE_USER) { 1697 debug_f("ignoring certificate %s: not a user " 1698 "certificate", options.identity_files[i]); 1699 continue; 1700 } 1701 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1702 debug_f("ignoring authenticator-hosted key %s as no " 1703 "SecurityKeyProvider has been specified", 1704 options.identity_files[i]); 1705 continue; 1706 } 1707 options.identity_keys[i] = NULL; 1708 id = xcalloc(1, sizeof(*id)); 1709 id->agent_fd = -1; 1710 id->key = key; 1711 id->filename = xstrdup(options.identity_files[i]); 1712 id->userprovided = options.identity_file_userprovided[i]; 1713 TAILQ_INSERT_TAIL(&files, id, next); 1714 } 1715 /* list of certificates specified by user */ 1716 for (i = 0; i < options.num_certificate_files; i++) { 1717 key = options.certificates[i]; 1718 if (!sshkey_is_cert(key) || key->cert == NULL || 1719 key->cert->type != SSH2_CERT_TYPE_USER) { 1720 debug_f("ignoring certificate %s: not a user " 1721 "certificate", options.identity_files[i]); 1722 continue; 1723 } 1724 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1725 debug_f("ignoring authenticator-hosted key " 1726 "certificate %s as no " 1727 "SecurityKeyProvider has been specified", 1728 options.identity_files[i]); 1729 continue; 1730 } 1731 id = xcalloc(1, sizeof(*id)); 1732 id->agent_fd = -1; 1733 id->key = key; 1734 id->filename = xstrdup(options.certificate_files[i]); 1735 id->userprovided = options.certificate_file_userprovided[i]; 1736 TAILQ_INSERT_TAIL(preferred, id, next); 1737 } 1738 /* list of keys supported by the agent */ 1739 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1740 for (j = 0; j < idlist->nkeys; j++) { 1741 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1742 options.required_rsa_size)) != 0) { 1743 debug_fr(r, "ignoring %s agent key", 1744 sshkey_ssh_name(idlist->keys[j])); 1745 continue; 1746 } 1747 found = 0; 1748 TAILQ_FOREACH(id, &files, next) { 1749 /* 1750 * agent keys from the config file are 1751 * preferred 1752 */ 1753 if (sshkey_equal(idlist->keys[j], id->key)) { 1754 TAILQ_REMOVE(&files, id, next); 1755 TAILQ_INSERT_TAIL(preferred, id, next); 1756 id->agent_fd = agent_fd; 1757 found = 1; 1758 break; 1759 } 1760 } 1761 if (!found && !options.identities_only) { 1762 id = xcalloc(1, sizeof(*id)); 1763 /* XXX "steals" key/comment from idlist */ 1764 id->key = idlist->keys[j]; 1765 id->filename = idlist->comments[j]; 1766 idlist->keys[j] = NULL; 1767 idlist->comments[j] = NULL; 1768 id->agent_fd = agent_fd; 1769 TAILQ_INSERT_TAIL(&agent, id, next); 1770 } 1771 } 1772 ssh_free_identitylist(idlist); 1773 /* append remaining agent keys */ 1774 TAILQ_CONCAT(preferred, &agent, next); 1775 authctxt->agent_fd = agent_fd; 1776 } 1777 /* Prefer PKCS11 keys that are explicitly listed */ 1778 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1779 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1780 continue; 1781 found = 0; 1782 TAILQ_FOREACH(id2, &files, next) { 1783 if (id2->key == NULL || 1784 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1785 continue; 1786 if (sshkey_equal(id->key, id2->key)) { 1787 TAILQ_REMOVE(&files, id, next); 1788 TAILQ_INSERT_TAIL(preferred, id, next); 1789 found = 1; 1790 break; 1791 } 1792 } 1793 /* If IdentitiesOnly set and key not found then don't use it */ 1794 if (!found && options.identities_only) { 1795 TAILQ_REMOVE(&files, id, next); 1796 freezero(id, sizeof(*id)); 1797 } 1798 } 1799 /* append remaining keys from the config file */ 1800 TAILQ_CONCAT(preferred, &files, next); 1801 /* finally, filter by PubkeyAcceptedAlgorithms */ 1802 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1803 disallowed = 0; 1804 cp = NULL; 1805 if (id->key == NULL) 1806 continue; 1807 if (!key_type_allowed_by_config(id->key)) { 1808 debug("Skipping %s key %s - corresponding algorithm " 1809 "not in PubkeyAcceptedAlgorithms", 1810 sshkey_ssh_name(id->key), id->filename); 1811 disallowed = 1; 1812 } else if (ssh->kex->server_sig_algs != NULL && 1813 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1814 debug("Skipping %s key %s - corresponding algorithm " 1815 "not supported by server", 1816 sshkey_ssh_name(id->key), id->filename); 1817 disallowed = 1; 1818 } 1819 free(cp); 1820 if (!disallowed) 1821 continue; 1822 /* remove key */ 1823 TAILQ_REMOVE(preferred, id, next); 1824 sshkey_free(id->key); 1825 free(id->filename); 1826 freezero(id, sizeof(*id)); 1827 } 1828 /* List the keys we plan on using */ 1829 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1830 ident = format_identity(id); 1831 debug("Will attempt key: %s", ident); 1832 free(ident); 1833 } 1834 debug2_f("done"); 1835 } 1836 1837 static void 1838 pubkey_cleanup(struct ssh *ssh) 1839 { 1840 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1841 Identity *id; 1842 1843 if (authctxt->agent_fd != -1) { 1844 ssh_close_authentication_socket(authctxt->agent_fd); 1845 authctxt->agent_fd = -1; 1846 } 1847 for (id = TAILQ_FIRST(&authctxt->keys); id; 1848 id = TAILQ_FIRST(&authctxt->keys)) { 1849 TAILQ_REMOVE(&authctxt->keys, id, next); 1850 sshkey_free(id->key); 1851 free(id->filename); 1852 free(id); 1853 } 1854 } 1855 1856 static void 1857 pubkey_reset(Authctxt *authctxt) 1858 { 1859 Identity *id; 1860 1861 TAILQ_FOREACH(id, &authctxt->keys, next) 1862 id->tried = 0; 1863 } 1864 1865 static int 1866 userauth_pubkey(struct ssh *ssh) 1867 { 1868 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1869 Identity *id; 1870 int sent = 0; 1871 char *ident; 1872 static int prepared; 1873 1874 if (!prepared) { 1875 pubkey_prepare(ssh, authctxt); 1876 prepared = 1; 1877 } 1878 1879 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1880 if (id->tried++) 1881 return (0); 1882 /* move key to the end of the queue */ 1883 TAILQ_REMOVE(&authctxt->keys, id, next); 1884 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1885 /* 1886 * send a test message if we have the public key. for 1887 * encrypted keys we cannot do this and have to load the 1888 * private key instead 1889 */ 1890 if (id->key != NULL) { 1891 ident = format_identity(id); 1892 debug("Offering public key: %s", ident); 1893 free(ident); 1894 sent = send_pubkey_test(ssh, id); 1895 } else { 1896 debug("Trying private key: %s", id->filename); 1897 id->key = load_identity_file(id); 1898 if (id->key != NULL) { 1899 id->isprivate = 1; 1900 sent = sign_and_send_pubkey(ssh, id); 1901 sshkey_free(id->key); 1902 id->key = NULL; 1903 id->isprivate = 0; 1904 } 1905 } 1906 if (sent) 1907 return (sent); 1908 } 1909 return (0); 1910 } 1911 1912 /* 1913 * Send userauth request message specifying keyboard-interactive method. 1914 */ 1915 static int 1916 userauth_kbdint(struct ssh *ssh) 1917 { 1918 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1919 int r; 1920 1921 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1922 return 0; 1923 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1924 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1925 debug3("userauth_kbdint: disable: no info_req_seen"); 1926 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1927 return 0; 1928 } 1929 1930 debug2("userauth_kbdint"); 1931 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1932 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1933 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1934 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1935 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1936 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1937 options.kbd_interactive_devices : "")) != 0 || 1938 (r = sshpkt_send(ssh)) != 0) 1939 fatal_fr(r, "send packet"); 1940 1941 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1942 return 1; 1943 } 1944 1945 /* 1946 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1947 */ 1948 static int 1949 input_userauth_info_req(int type, uint32_t seq, struct ssh *ssh) 1950 { 1951 Authctxt *authctxt = ssh->authctxt; 1952 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1953 char *display_prompt = NULL, *response = NULL; 1954 u_char echo = 0; 1955 u_int num_prompts, i; 1956 int r, addnl; 1957 size_t len; 1958 1959 debug2_f("entering"); 1960 1961 if (authctxt == NULL) 1962 fatal_f("no authentication context"); 1963 1964 authctxt->info_req_seen = 1; 1965 1966 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1967 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1968 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1969 goto out; 1970 if ((len = strlen(name)) > 0) { 1971 addnl = name[len] != '\n'; 1972 fmprintf(stderr, "%s%s", name, addnl ? "\n" : ""); 1973 } 1974 if ((len = strlen(inst)) > 0) { 1975 addnl = inst[len] != '\n'; 1976 fmprintf(stderr, "%s%s", inst, addnl ? "\n" : ""); 1977 } 1978 1979 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1980 goto out; 1981 /* 1982 * Begin to build info response packet based on prompts requested. 1983 * We commit to providing the correct number of responses, so if 1984 * further on we run into a problem that prevents this, we have to 1985 * be sure and clean this up and send a correct error response. 1986 */ 1987 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1988 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1989 goto out; 1990 1991 debug2_f("num_prompts %d", num_prompts); 1992 for (i = 0; i < num_prompts; i++) { 1993 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1994 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1995 goto out; 1996 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1997 authctxt->server_user, options.host_key_alias ? 1998 options.host_key_alias : authctxt->host, prompt) == -1) 1999 fatal_f("asmprintf failed"); 2000 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2001 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2002 goto out; 2003 freezero(response, strlen(response)); 2004 free(prompt); 2005 free(display_prompt); 2006 display_prompt = response = prompt = NULL; 2007 } 2008 /* done with parsing incoming message. */ 2009 if ((r = sshpkt_get_end(ssh)) != 0 || 2010 (r = sshpkt_add_padding(ssh, 64)) != 0) 2011 goto out; 2012 r = sshpkt_send(ssh); 2013 out: 2014 if (response) 2015 freezero(response, strlen(response)); 2016 free(prompt); 2017 free(display_prompt); 2018 free(name); 2019 free(inst); 2020 free(lang); 2021 return r; 2022 } 2023 2024 static int 2025 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2026 const u_char *data, size_t datalen) 2027 { 2028 struct sshbuf *b; 2029 struct stat st; 2030 pid_t pid; 2031 int r, to[2], from[2], status; 2032 int sock = ssh_packet_get_connection_in(ssh); 2033 u_char rversion = 0, version = 2; 2034 void (*osigchld)(int); 2035 2036 *sigp = NULL; 2037 *lenp = 0; 2038 2039 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2040 error_f("not installed: %s", strerror(errno)); 2041 return -1; 2042 } 2043 if (fflush(stdout) != 0) { 2044 error_f("fflush: %s", strerror(errno)); 2045 return -1; 2046 } 2047 if (pipe(to) == -1) { 2048 error_f("pipe: %s", strerror(errno)); 2049 return -1; 2050 } 2051 if (pipe(from) == -1) { 2052 error_f("pipe: %s", strerror(errno)); 2053 return -1; 2054 } 2055 if ((pid = fork()) == -1) { 2056 error_f("fork: %s", strerror(errno)); 2057 return -1; 2058 } 2059 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2060 if (pid == 0) { 2061 close(from[0]); 2062 if (dup2(from[1], STDOUT_FILENO) == -1) 2063 fatal_f("dup2: %s", strerror(errno)); 2064 close(to[1]); 2065 if (dup2(to[0], STDIN_FILENO) == -1) 2066 fatal_f("dup2: %s", strerror(errno)); 2067 close(from[1]); 2068 close(to[0]); 2069 2070 if (dup2(sock, STDERR_FILENO + 1) == -1) 2071 fatal_f("dup2: %s", strerror(errno)); 2072 sock = STDERR_FILENO + 1; 2073 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2074 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2075 closefrom(sock + 1); 2076 2077 debug3_f("[child] pid=%ld, exec %s", 2078 (long)getpid(), _PATH_SSH_KEY_SIGN); 2079 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2080 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2081 strerror(errno)); 2082 } 2083 close(from[1]); 2084 close(to[0]); 2085 sock = STDERR_FILENO + 1; 2086 2087 if ((b = sshbuf_new()) == NULL) 2088 fatal_f("sshbuf_new failed"); 2089 /* send # of sock, data to be signed */ 2090 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2091 (r = sshbuf_put_string(b, data, datalen)) != 0) 2092 fatal_fr(r, "buffer error"); 2093 if (ssh_msg_send(to[1], version, b) == -1) 2094 fatal_f("couldn't send request"); 2095 sshbuf_reset(b); 2096 r = ssh_msg_recv(from[0], b); 2097 close(from[0]); 2098 close(to[1]); 2099 if (r < 0) { 2100 error_f("no reply"); 2101 goto fail; 2102 } 2103 2104 errno = 0; 2105 while (waitpid(pid, &status, 0) == -1) { 2106 if (errno != EINTR) { 2107 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2108 goto fail; 2109 } 2110 } 2111 if (!WIFEXITED(status)) { 2112 error_f("exited abnormally"); 2113 goto fail; 2114 } 2115 if (WEXITSTATUS(status) != 0) { 2116 error_f("exited with status %d", WEXITSTATUS(status)); 2117 goto fail; 2118 } 2119 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2120 error_fr(r, "buffer error"); 2121 goto fail; 2122 } 2123 if (rversion != version) { 2124 error_f("bad version"); 2125 goto fail; 2126 } 2127 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2128 error_fr(r, "buffer error"); 2129 fail: 2130 ssh_signal(SIGCHLD, osigchld); 2131 sshbuf_free(b); 2132 return -1; 2133 } 2134 ssh_signal(SIGCHLD, osigchld); 2135 sshbuf_free(b); 2136 2137 return 0; 2138 } 2139 2140 static int 2141 userauth_hostbased(struct ssh *ssh) 2142 { 2143 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2144 struct sshkey *private = NULL; 2145 struct sshbuf *b = NULL; 2146 u_char *sig = NULL, *keyblob = NULL; 2147 char *fp = NULL, *chost = NULL, *lname = NULL; 2148 size_t siglen = 0, keylen = 0; 2149 int i, r, success = 0; 2150 2151 if (authctxt->ktypes == NULL) { 2152 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2153 authctxt->ktypes = authctxt->oktypes; 2154 } 2155 2156 /* 2157 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2158 * trying each hostkey that matches the type in turn. 2159 */ 2160 for (;;) { 2161 if (authctxt->active_ktype == NULL) 2162 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2163 if (authctxt->active_ktype == NULL || 2164 *authctxt->active_ktype == '\0') 2165 break; 2166 debug3_f("trying key type %s", authctxt->active_ktype); 2167 2168 /* check for a useful key */ 2169 private = NULL; 2170 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2171 if (authctxt->sensitive->keys[i] == NULL || 2172 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2173 continue; 2174 if (!sshkey_match_keyname_to_sigalgs( 2175 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2176 authctxt->active_ktype)) 2177 continue; 2178 /* we take and free the key */ 2179 private = authctxt->sensitive->keys[i]; 2180 authctxt->sensitive->keys[i] = NULL; 2181 break; 2182 } 2183 /* Found one */ 2184 if (private != NULL) 2185 break; 2186 /* No more keys of this type; advance */ 2187 authctxt->active_ktype = NULL; 2188 } 2189 if (private == NULL) { 2190 free(authctxt->oktypes); 2191 authctxt->oktypes = authctxt->ktypes = NULL; 2192 authctxt->active_ktype = NULL; 2193 debug("No more client hostkeys for hostbased authentication."); 2194 goto out; 2195 } 2196 2197 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2198 SSH_FP_DEFAULT)) == NULL) { 2199 error_f("sshkey_fingerprint failed"); 2200 goto out; 2201 } 2202 debug_f("trying hostkey %s %s using sigalg %s", 2203 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2204 2205 /* figure out a name for the client host */ 2206 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2207 if (lname == NULL) { 2208 error_f("cannot get local ipaddr/name"); 2209 goto out; 2210 } 2211 2212 /* XXX sshbuf_put_stringf? */ 2213 xasprintf(&chost, "%s.", lname); 2214 debug2_f("chost %s", chost); 2215 2216 /* construct data */ 2217 if ((b = sshbuf_new()) == NULL) { 2218 error_f("sshbuf_new failed"); 2219 goto out; 2220 } 2221 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2222 error_fr(r, "sshkey_to_blob"); 2223 goto out; 2224 } 2225 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2226 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2227 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2228 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2229 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2230 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2231 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2232 (r = sshbuf_put_cstring(b, chost)) != 0 || 2233 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2234 error_fr(r, "buffer error"); 2235 goto out; 2236 } 2237 2238 #ifdef DEBUG_PK 2239 sshbuf_dump(b, stderr); 2240 #endif 2241 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2242 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2243 error("sign using hostkey %s %s failed", 2244 sshkey_ssh_name(private), fp); 2245 goto out; 2246 } 2247 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2248 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2249 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2250 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2251 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2252 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2253 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2254 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2255 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2256 (r = sshpkt_send(ssh)) != 0) { 2257 error_fr(r, "packet error"); 2258 goto out; 2259 } 2260 success = 1; 2261 2262 out: 2263 if (sig != NULL) 2264 freezero(sig, siglen); 2265 free(keyblob); 2266 free(lname); 2267 free(fp); 2268 free(chost); 2269 sshkey_free(private); 2270 sshbuf_free(b); 2271 2272 return success; 2273 } 2274 2275 /* find auth method */ 2276 2277 /* 2278 * given auth method name, if configurable options permit this method fill 2279 * in auth_ident field and return true, otherwise return false. 2280 */ 2281 static int 2282 authmethod_is_enabled(Authmethod *method) 2283 { 2284 if (method == NULL) 2285 return 0; 2286 /* return false if options indicate this method is disabled */ 2287 if (method->enabled == NULL || *method->enabled == 0) 2288 return 0; 2289 /* return false if batch mode is enabled but method needs interactive mode */ 2290 if (method->batch_flag != NULL && *method->batch_flag != 0) 2291 return 0; 2292 return 1; 2293 } 2294 2295 static Authmethod * 2296 authmethod_lookup(const char *name) 2297 { 2298 Authmethod *method = NULL; 2299 if (name != NULL) 2300 for (method = authmethods; method->name != NULL; method++) 2301 if (strcmp(name, method->name) == 0) 2302 return method; 2303 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2304 return NULL; 2305 } 2306 2307 /* XXX internal state */ 2308 static Authmethod *current = NULL; 2309 static char *supported = NULL; 2310 static char *preferred = NULL; 2311 2312 /* 2313 * Given the authentication method list sent by the server, return the 2314 * next method we should try. If the server initially sends a nil list, 2315 * use a built-in default list. 2316 */ 2317 static Authmethod * 2318 authmethod_get(char *authlist) 2319 { 2320 char *name = NULL; 2321 u_int next; 2322 2323 /* Use a suitable default if we're passed a nil list. */ 2324 if (authlist == NULL || strlen(authlist) == 0) 2325 authlist = options.preferred_authentications; 2326 2327 if (supported == NULL || strcmp(authlist, supported) != 0) { 2328 debug3("start over, passed a different list %s", authlist); 2329 free(supported); 2330 supported = xstrdup(authlist); 2331 preferred = options.preferred_authentications; 2332 debug3("preferred %s", preferred); 2333 current = NULL; 2334 } else if (current != NULL && authmethod_is_enabled(current)) 2335 return current; 2336 2337 for (;;) { 2338 if ((name = match_list(preferred, supported, &next)) == NULL) { 2339 debug("No more authentication methods to try."); 2340 current = NULL; 2341 return NULL; 2342 } 2343 preferred += next; 2344 debug3("authmethod_lookup %s", name); 2345 debug3("remaining preferred: %s", preferred); 2346 if ((current = authmethod_lookup(name)) != NULL && 2347 authmethod_is_enabled(current)) { 2348 debug3("authmethod_is_enabled %s", name); 2349 debug("Next authentication method: %s", name); 2350 free(name); 2351 return current; 2352 } 2353 free(name); 2354 } 2355 } 2356 2357 static char * 2358 authmethods_get(void) 2359 { 2360 Authmethod *method = NULL; 2361 struct sshbuf *b; 2362 char *list; 2363 int r; 2364 2365 if ((b = sshbuf_new()) == NULL) 2366 fatal_f("sshbuf_new failed"); 2367 for (method = authmethods; method->name != NULL; method++) { 2368 if (authmethod_is_enabled(method)) { 2369 if ((r = sshbuf_putf(b, "%s%s", 2370 sshbuf_len(b) ? "," : "", method->name)) != 0) 2371 fatal_fr(r, "buffer error"); 2372 } 2373 } 2374 if ((list = sshbuf_dup_string(b)) == NULL) 2375 fatal_f("sshbuf_dup_string failed"); 2376 sshbuf_free(b); 2377 return list; 2378 } 2379