1 /* $OpenBSD: sshconnect2.c,v 1.388 2026/07/06 07:49:58 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_storage 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, (struct sockaddr *)&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_storage *hostaddr, 220 u_short port, 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 = xstrdup(host); 227 xxx_hostaddr = *hostaddr; 228 xxx_conn_info = ssh_conn_info_dup(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, (struct sockaddr *)hostaddr, 253 port, cinfo); 254 } 255 256 kex_proposal_populate_entries(ssh, myproposal, 257 options.kex_algorithms, options.ciphers, options.macs, 258 compression_alg_list(options.compression), 259 hkalgs ? hkalgs : options.hostkeyalgorithms); 260 261 free(hkalgs); 262 263 /* start key exchange */ 264 if ((r = kex_setup(ssh, myproposal)) != 0) 265 fatal_r(r, "kex_setup"); 266 #ifdef WITH_OPENSSL 267 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 270 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 272 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 273 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 274 # ifdef OPENSSL_HAS_ECC 275 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 276 # endif 277 #endif 278 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 279 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 280 ssh->kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_client; 281 ssh->kex->verify_host_key=&verify_host_key_callback; 282 283 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 284 kex_proposal_free_entries(myproposal); 285 286 #ifdef DEBUG_KEXDH 287 /* send 1st encrypted/maced/compressed message */ 288 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 289 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 290 (r = sshpkt_send(ssh)) != 0 || 291 (r = ssh_packet_write_wait(ssh)) != 0) 292 fatal_fr(r, "send packet"); 293 #endif 294 } 295 296 /* 297 * Authenticate user 298 */ 299 300 typedef struct cauthctxt Authctxt; 301 typedef struct cauthmethod Authmethod; 302 typedef struct identity Identity; 303 typedef struct idlist Idlist; 304 305 struct identity { 306 TAILQ_ENTRY(identity) next; 307 int agent_fd; /* >=0 if agent supports key */ 308 struct sshkey *key; /* public/private key */ 309 char *filename; /* comment for agent-only keys */ 310 int tried; 311 int isprivate; /* key points to the private key */ 312 int userprovided; 313 }; 314 TAILQ_HEAD(idlist, identity); 315 316 struct cauthctxt { 317 const char *server_user; 318 const char *local_user; 319 const char *host; 320 const char *service; 321 struct cauthmethod *method; 322 sig_atomic_t success; 323 char *authlist; 324 #ifdef GSSAPI 325 /* gssapi */ 326 gss_OID_set gss_supported_mechs; 327 u_int mech_tried; 328 #endif 329 /* pubkey */ 330 struct idlist keys; 331 int agent_fd; 332 /* hostbased */ 333 Sensitive *sensitive; 334 char *oktypes, *ktypes; 335 const char *active_ktype; 336 /* kbd-interactive */ 337 int info_req_seen; 338 int attempt_kbdint; 339 /* password */ 340 int attempt_passwd; 341 /* generic */ 342 void *methoddata; 343 }; 344 345 struct cauthmethod { 346 char *name; /* string to compare against server's list */ 347 int (*userauth)(struct ssh *ssh); 348 void (*cleanup)(struct ssh *ssh); 349 int *enabled; /* flag in option struct that enables method */ 350 int *batch_flag; /* flag in option struct that disables method */ 351 }; 352 353 static int input_userauth_service_accept(int, uint32_t, struct ssh *); 354 static int input_userauth_success(int, uint32_t, struct ssh *); 355 static int input_userauth_failure(int, uint32_t, struct ssh *); 356 static int input_userauth_banner(int, uint32_t, struct ssh *); 357 static int input_userauth_error(int, uint32_t, struct ssh *); 358 static int input_userauth_info_req(int, uint32_t, struct ssh *); 359 static int input_userauth_pk_ok(int, uint32_t, struct ssh *); 360 static int input_userauth_passwd_changereq(int, uint32_t, struct ssh *); 361 362 static int userauth_none(struct ssh *); 363 static int userauth_pubkey(struct ssh *); 364 static int userauth_passwd(struct ssh *); 365 static int userauth_kbdint(struct ssh *); 366 static int userauth_hostbased(struct ssh *); 367 368 #ifdef GSSAPI 369 static int userauth_gssapi(struct ssh *); 370 static void userauth_gssapi_cleanup(struct ssh *); 371 static int input_gssapi_response(int type, uint32_t, struct ssh *); 372 static int input_gssapi_token(int type, uint32_t, struct ssh *); 373 static int input_gssapi_error(int, uint32_t, struct ssh *); 374 static int input_gssapi_errtok(int, uint32_t, struct ssh *); 375 #endif 376 377 void userauth(struct ssh *, char *); 378 379 static void pubkey_cleanup(struct ssh *); 380 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 381 static void pubkey_prepare(struct ssh *, Authctxt *); 382 static void pubkey_reset(Authctxt *); 383 static struct sshkey *load_identity_file(Identity *); 384 385 static Authmethod *authmethod_get(char *authlist); 386 static Authmethod *authmethod_lookup(const char *name); 387 static char *authmethods_get(void); 388 389 Authmethod authmethods[] = { 390 #ifdef GSSAPI 391 {"gssapi-with-mic", 392 userauth_gssapi, 393 userauth_gssapi_cleanup, 394 &options.gss_authentication, 395 NULL}, 396 #endif 397 {"hostbased", 398 userauth_hostbased, 399 NULL, 400 &options.hostbased_authentication, 401 NULL}, 402 {"publickey", 403 userauth_pubkey, 404 NULL, 405 &options.pubkey_authentication, 406 NULL}, 407 {"keyboard-interactive", 408 userauth_kbdint, 409 NULL, 410 &options.kbd_interactive_authentication, 411 &options.batch_mode}, 412 {"password", 413 userauth_passwd, 414 NULL, 415 &options.password_authentication, 416 &options.batch_mode}, 417 {"none", 418 userauth_none, 419 NULL, 420 NULL, 421 NULL}, 422 {NULL, NULL, NULL, NULL, NULL} 423 }; 424 425 void 426 ssh_userauth2(struct ssh *ssh, const char *local_user, 427 const char *server_user, char *host, Sensitive *sensitive) 428 { 429 Authctxt authctxt; 430 int r; 431 432 if (options.preferred_authentications == NULL) 433 options.preferred_authentications = authmethods_get(); 434 435 /* setup authentication context */ 436 memset(&authctxt, 0, sizeof(authctxt)); 437 authctxt.server_user = server_user; 438 authctxt.local_user = local_user; 439 authctxt.host = host; 440 authctxt.service = "ssh-connection"; /* service name */ 441 authctxt.success = 0; 442 authctxt.method = authmethod_lookup("none"); 443 authctxt.authlist = NULL; 444 authctxt.methoddata = NULL; 445 authctxt.sensitive = sensitive; 446 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 447 authctxt.info_req_seen = 0; 448 authctxt.attempt_kbdint = 0; 449 authctxt.attempt_passwd = 0; 450 #if GSSAPI 451 authctxt.gss_supported_mechs = NULL; 452 authctxt.mech_tried = 0; 453 #endif 454 authctxt.agent_fd = -1; 455 if (authctxt.method == NULL) 456 fatal_f("internal error: cannot send userauth none request"); 457 458 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 459 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 460 (r = sshpkt_send(ssh)) != 0) 461 fatal_fr(r, "send packet"); 462 463 ssh->authctxt = &authctxt; 464 ssh_dispatch_init(ssh, &input_userauth_error); 465 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 466 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 467 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 468 pubkey_cleanup(ssh); 469 #ifdef GSSAPI 470 if (authctxt.gss_supported_mechs != NULL) { 471 u_int ms; 472 473 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 474 authctxt.gss_supported_mechs = NULL; 475 } 476 #endif 477 ssh->authctxt = NULL; 478 479 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 480 481 if (!authctxt.success) 482 fatal("Authentication failed."); 483 if (ssh_packet_connection_is_on_socket(ssh)) { 484 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 485 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 486 authctxt.method->name); 487 } else { 488 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 489 authctxt.method->name); 490 } 491 } 492 493 static int 494 input_userauth_service_accept(int type, uint32_t seq, struct ssh *ssh) 495 { 496 int r; 497 498 if (ssh_packet_remaining(ssh) > 0) { 499 char *reply; 500 501 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 502 goto out; 503 debug2("service_accept: %s", reply); 504 free(reply); 505 } else { 506 debug2("buggy server: service_accept w/o service"); 507 } 508 if ((r = sshpkt_get_end(ssh)) != 0) 509 goto out; 510 debug("SSH2_MSG_SERVICE_ACCEPT received"); 511 512 /* initial userauth request */ 513 userauth_none(ssh); 514 515 /* accept EXT_INFO at any time during userauth */ 516 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 517 &kex_input_ext_info : &input_userauth_error); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 519 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 520 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 521 r = 0; 522 out: 523 return r; 524 } 525 526 void 527 userauth(struct ssh *ssh, char *authlist) 528 { 529 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 530 531 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 532 authctxt->method->cleanup(ssh); 533 534 free(authctxt->methoddata); 535 authctxt->methoddata = NULL; 536 if (authlist == NULL) { 537 authlist = authctxt->authlist; 538 } else { 539 free(authctxt->authlist); 540 authctxt->authlist = authlist; 541 } 542 for (;;) { 543 Authmethod *method = authmethod_get(authlist); 544 if (method == NULL) 545 fatal("%s@%s: Permission denied (%s).", 546 authctxt->server_user, authctxt->host, authlist); 547 authctxt->method = method; 548 549 /* reset the per method handler */ 550 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 551 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 552 553 /* and try new method */ 554 if (method->userauth(ssh) != 0) { 555 debug2("we sent a %s packet, wait for reply", method->name); 556 break; 557 } else { 558 debug2("we did not send a packet, disable method"); 559 method->enabled = NULL; 560 } 561 } 562 } 563 564 static int 565 input_userauth_error(int type, uint32_t seq, struct ssh *ssh) 566 { 567 fatal_f("bad message during authentication: type %d", type); 568 return 0; 569 } 570 571 static int 572 input_userauth_banner(int type, uint32_t seq, struct ssh *ssh) 573 { 574 char *msg = NULL; 575 size_t len; 576 int r; 577 578 debug3_f("entering"); 579 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 580 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 581 goto out; 582 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 583 fmprintf(stderr, "%s", msg); 584 r = 0; 585 out: 586 free(msg); 587 return r; 588 } 589 590 static int 591 input_userauth_success(int type, uint32_t seq, struct ssh *ssh) 592 { 593 Authctxt *authctxt = ssh->authctxt; 594 595 if (authctxt == NULL) 596 fatal_f("no authentication context"); 597 free(authctxt->authlist); 598 authctxt->authlist = NULL; 599 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 600 authctxt->method->cleanup(ssh); 601 free(authctxt->methoddata); 602 authctxt->methoddata = NULL; 603 authctxt->success = 1; /* break out */ 604 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 605 return 0; 606 } 607 608 #if 0 609 static int 610 input_userauth_success_unexpected(int type, uint32_t seq, struct ssh *ssh) 611 { 612 Authctxt *authctxt = ssh->authctxt; 613 614 if (authctxt == NULL) 615 fatal_f("no authentication context"); 616 617 fatal("Unexpected authentication success during %s.", 618 authctxt->method->name); 619 return 0; 620 } 621 #endif 622 623 static int 624 input_userauth_failure(int type, uint32_t seq, struct ssh *ssh) 625 { 626 Authctxt *authctxt = ssh->authctxt; 627 char *authlist = NULL; 628 u_char partial; 629 630 if (authctxt == NULL) 631 fatal("input_userauth_failure: no authentication context"); 632 633 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 634 sshpkt_get_u8(ssh, &partial) != 0 || 635 sshpkt_get_end(ssh) != 0) 636 goto out; 637 638 if (partial != 0) { 639 verbose("Authenticated using \"%s\" with partial success.", 640 authctxt->method->name); 641 /* reset state */ 642 pubkey_reset(authctxt); 643 } 644 debug("Authentications that can continue: %s", authlist); 645 646 userauth(ssh, authlist); 647 authlist = NULL; 648 out: 649 free(authlist); 650 return 0; 651 } 652 653 /* 654 * Format an identity for logging including filename, key type, fingerprint 655 * and location (agent, etc.). Caller must free. 656 */ 657 static char * 658 format_identity(Identity *id) 659 { 660 char *fp = NULL, *ret = NULL; 661 const char *note = ""; 662 663 if (id->key != NULL) { 664 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 665 SSH_FP_DEFAULT); 666 } 667 if (id->key) { 668 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 669 note = " token"; 670 else if (sshkey_is_sk(id->key)) 671 note = " authenticator"; 672 } 673 xasprintf(&ret, "%s %s%s%s%s%s%s", 674 id->filename, 675 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 676 fp ? fp : "", 677 id->userprovided ? " explicit" : "", note, 678 id->agent_fd != -1 ? " agent" : ""); 679 free(fp); 680 return ret; 681 } 682 683 static int 684 input_userauth_pk_ok(int type, uint32_t seq, struct ssh *ssh) 685 { 686 Authctxt *authctxt = ssh->authctxt; 687 struct sshkey *key = NULL; 688 Identity *id = NULL; 689 int pktype, found = 0, sent = 0; 690 size_t blen; 691 char *pkalg = NULL, *fp = NULL, *ident = NULL; 692 u_char *pkblob = NULL; 693 int r; 694 695 if (authctxt == NULL) 696 fatal("input_userauth_pk_ok: no authentication context"); 697 698 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 699 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 700 (r = sshpkt_get_end(ssh)) != 0) 701 goto done; 702 703 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 704 debug_f("server sent unknown pkalg %s", pkalg); 705 r = SSH_ERR_INVALID_FORMAT; 706 goto done; 707 } 708 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 709 debug_r(r, "no key from blob. pkalg %s", pkalg); 710 goto done; 711 } 712 if (key->type != pktype) { 713 error("input_userauth_pk_ok: type mismatch " 714 "for decoded key (received %d, expected %d)", 715 key->type, pktype); 716 r = SSH_ERR_INVALID_FORMAT; 717 goto done; 718 } 719 720 /* 721 * search keys in the reverse order, because last candidate has been 722 * moved to the end of the queue. this also avoids confusion by 723 * duplicate keys 724 */ 725 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 726 if (sshkey_equal(key, id->key)) { 727 found = 1; 728 break; 729 } 730 } 731 if (!found || id == NULL) { 732 fp = sshkey_fingerprint(key, options.fingerprint_hash, 733 SSH_FP_DEFAULT); 734 error_f("server replied with unknown key: %s %s", 735 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 736 r = SSH_ERR_INVALID_FORMAT; 737 goto done; 738 } 739 ident = format_identity(id); 740 debug("Server accepts key: %s", ident); 741 sent = sign_and_send_pubkey(ssh, id); 742 r = 0; 743 done: 744 sshkey_free(key); 745 free(ident); 746 free(fp); 747 free(pkalg); 748 free(pkblob); 749 750 /* try another method if we did not send a packet */ 751 if (r == 0 && sent == 0) 752 userauth(ssh, NULL); 753 return r; 754 } 755 756 #ifdef GSSAPI 757 static int 758 userauth_gssapi(struct ssh *ssh) 759 { 760 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 761 Gssctxt *gssctxt = NULL; 762 OM_uint32 min; 763 int r, ok = 0; 764 gss_OID mech = NULL; 765 766 /* Try one GSSAPI method at a time, rather than sending them all at 767 * once. */ 768 769 if (authctxt->gss_supported_mechs == NULL) 770 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 771 772 /* Check to see whether the mechanism is usable before we offer it */ 773 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 774 !ok) { 775 mech = &authctxt->gss_supported_mechs-> 776 elements[authctxt->mech_tried]; 777 /* My DER encoding requires length<128 */ 778 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 779 mech, authctxt->host)) { 780 ok = 1; /* Mechanism works */ 781 } else { 782 authctxt->mech_tried++; 783 } 784 } 785 786 if (!ok || mech == NULL) 787 return 0; 788 789 authctxt->methoddata=(void *)gssctxt; 790 791 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 792 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 793 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 794 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 795 (r = sshpkt_put_u32(ssh, 1)) != 0 || 796 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 797 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 798 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 799 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 800 (r = sshpkt_send(ssh)) != 0) 801 fatal_fr(r, "send packet"); 802 803 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 804 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 805 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 806 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 807 808 authctxt->mech_tried++; /* Move along to next candidate */ 809 810 return 1; 811 } 812 813 static void 814 userauth_gssapi_cleanup(struct ssh *ssh) 815 { 816 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 817 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 818 819 ssh_gssapi_delete_ctx(&gssctxt); 820 authctxt->methoddata = NULL; 821 } 822 823 static OM_uint32 824 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 825 { 826 Authctxt *authctxt = ssh->authctxt; 827 Gssctxt *gssctxt = authctxt->methoddata; 828 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 829 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 830 gss_buffer_desc gssbuf; 831 OM_uint32 status, ms, flags; 832 int r; 833 834 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 835 recv_tok, &send_tok, &flags); 836 837 if (send_tok.length > 0) { 838 u_char type = GSS_ERROR(status) ? 839 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 840 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 841 842 if ((r = sshpkt_start(ssh, type)) != 0 || 843 (r = sshpkt_put_string(ssh, send_tok.value, 844 send_tok.length)) != 0 || 845 (r = sshpkt_send(ssh)) != 0) 846 fatal_fr(r, "send %u packet", type); 847 848 gss_release_buffer(&ms, &send_tok); 849 } 850 851 if (status == GSS_S_COMPLETE) { 852 /* send either complete or MIC, depending on mechanism */ 853 if (!(flags & GSS_C_INTEG_FLAG)) { 854 if ((r = sshpkt_start(ssh, 855 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 856 (r = sshpkt_send(ssh)) != 0) 857 fatal_fr(r, "send completion"); 858 } else { 859 struct sshbuf *b; 860 861 if ((b = sshbuf_new()) == NULL) 862 fatal_f("sshbuf_new failed"); 863 ssh_gssapi_buildmic(b, authctxt->server_user, 864 authctxt->service, "gssapi-with-mic", 865 ssh->kex->session_id); 866 867 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 868 fatal_f("sshbuf_mutable_ptr failed"); 869 gssbuf.length = sshbuf_len(b); 870 871 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 872 873 if (!GSS_ERROR(status)) { 874 if ((r = sshpkt_start(ssh, 875 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 876 (r = sshpkt_put_string(ssh, mic.value, 877 mic.length)) != 0 || 878 (r = sshpkt_send(ssh)) != 0) 879 fatal_fr(r, "send MIC"); 880 } 881 882 sshbuf_free(b); 883 gss_release_buffer(&ms, &mic); 884 } 885 } 886 887 return status; 888 } 889 890 static int 891 input_gssapi_response(int type, uint32_t plen, struct ssh *ssh) 892 { 893 Authctxt *authctxt = ssh->authctxt; 894 Gssctxt *gssctxt; 895 size_t oidlen; 896 u_char *oidv = NULL; 897 int r; 898 899 if (authctxt == NULL) 900 fatal("input_gssapi_response: no authentication context"); 901 gssctxt = authctxt->methoddata; 902 903 /* Setup our OID */ 904 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 905 goto done; 906 907 if (oidlen <= 2 || 908 oidv[0] != SSH_GSS_OIDTYPE || 909 oidv[1] != oidlen - 2) { 910 debug("Badly encoded mechanism OID received"); 911 userauth(ssh, NULL); 912 goto ok; 913 } 914 915 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 916 fatal("Server returned different OID than expected"); 917 918 if ((r = sshpkt_get_end(ssh)) != 0) 919 goto done; 920 921 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 922 /* Start again with next method on list */ 923 debug("Trying to start again"); 924 userauth(ssh, NULL); 925 goto ok; 926 } 927 ok: 928 r = 0; 929 done: 930 free(oidv); 931 return r; 932 } 933 934 static int 935 input_gssapi_token(int type, uint32_t plen, struct ssh *ssh) 936 { 937 Authctxt *authctxt = ssh->authctxt; 938 gss_buffer_desc recv_tok; 939 u_char *p = NULL; 940 size_t len; 941 OM_uint32 status; 942 int r; 943 944 if (authctxt == NULL) 945 fatal("input_gssapi_response: no authentication context"); 946 947 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 948 (r = sshpkt_get_end(ssh)) != 0) 949 goto out; 950 951 recv_tok.value = p; 952 recv_tok.length = len; 953 status = process_gssapi_token(ssh, &recv_tok); 954 955 /* Start again with the next method in the list */ 956 if (GSS_ERROR(status)) { 957 userauth(ssh, NULL); 958 /* ok */ 959 } 960 r = 0; 961 out: 962 free(p); 963 return r; 964 } 965 966 static int 967 input_gssapi_errtok(int type, uint32_t plen, struct ssh *ssh) 968 { 969 Authctxt *authctxt = ssh->authctxt; 970 Gssctxt *gssctxt; 971 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 972 gss_buffer_desc recv_tok; 973 OM_uint32 ms; 974 u_char *p = NULL; 975 size_t len; 976 int r; 977 978 if (authctxt == NULL) 979 fatal("input_gssapi_response: no authentication context"); 980 gssctxt = authctxt->methoddata; 981 982 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 983 (r = sshpkt_get_end(ssh)) != 0) { 984 free(p); 985 return r; 986 } 987 988 /* Stick it into GSSAPI and see what it says */ 989 recv_tok.value = p; 990 recv_tok.length = len; 991 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 992 &recv_tok, &send_tok, NULL); 993 free(p); 994 gss_release_buffer(&ms, &send_tok); 995 996 /* Server will be returning a failed packet after this one */ 997 return 0; 998 } 999 1000 static int 1001 input_gssapi_error(int type, uint32_t plen, struct ssh *ssh) 1002 { 1003 char *msg = NULL; 1004 char *lang = NULL; 1005 int r; 1006 1007 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1008 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1009 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1010 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1011 goto out; 1012 r = sshpkt_get_end(ssh); 1013 debug("Server GSSAPI Error:\n%s", msg); 1014 out: 1015 free(msg); 1016 free(lang); 1017 return r; 1018 } 1019 #endif /* GSSAPI */ 1020 1021 static int 1022 userauth_none(struct ssh *ssh) 1023 { 1024 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1025 int r; 1026 1027 /* initial userauth request */ 1028 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1029 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1030 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1031 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1032 (r = sshpkt_send(ssh)) != 0) 1033 fatal_fr(r, "send packet"); 1034 return 1; 1035 } 1036 1037 static int 1038 userauth_passwd(struct ssh *ssh) 1039 { 1040 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1041 char *password, *prompt = NULL; 1042 const char *host = options.host_key_alias ? options.host_key_alias : 1043 authctxt->host; 1044 int r; 1045 1046 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1047 return 0; 1048 1049 if (authctxt->attempt_passwd != 1) 1050 error("Permission denied, please try again."); 1051 1052 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1053 password = read_passphrase(prompt, 0); 1054 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1056 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1057 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1058 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1059 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1060 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1061 (r = sshpkt_send(ssh)) != 0) 1062 fatal_fr(r, "send packet"); 1063 1064 free(prompt); 1065 if (password != NULL) 1066 freezero(password, strlen(password)); 1067 1068 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1069 &input_userauth_passwd_changereq); 1070 1071 return 1; 1072 } 1073 1074 /* 1075 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1076 */ 1077 static int 1078 input_userauth_passwd_changereq(int type, uint32_t seqnr, struct ssh *ssh) 1079 { 1080 Authctxt *authctxt = ssh->authctxt; 1081 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1082 char prompt[256]; 1083 const char *host; 1084 int r, addnl; 1085 size_t len; 1086 1087 debug2("input_userauth_passwd_changereq"); 1088 1089 if (authctxt == NULL) 1090 fatal("input_userauth_passwd_changereq: " 1091 "no authentication context"); 1092 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1093 1094 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1095 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1096 goto out; 1097 if ((len = strlen(info)) > 0) { 1098 addnl = info[len] != '\n'; 1099 fmprintf(stderr, "%s%s", info, addnl ? "\n" : ""); 1100 } 1101 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1102 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1103 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1104 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1105 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1106 goto out; 1107 1108 snprintf(prompt, sizeof(prompt), 1109 "Enter %.30s@%.128s's old password: ", 1110 authctxt->server_user, host); 1111 password = read_passphrase(prompt, 0); 1112 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1113 goto out; 1114 1115 freezero(password, strlen(password)); 1116 password = NULL; 1117 while (password == NULL) { 1118 snprintf(prompt, sizeof(prompt), 1119 "Enter %.30s@%.128s's new password: ", 1120 authctxt->server_user, host); 1121 password = read_passphrase(prompt, RP_ALLOW_EOF); 1122 if (password == NULL) { 1123 /* bail out */ 1124 r = 0; 1125 goto out; 1126 } 1127 snprintf(prompt, sizeof(prompt), 1128 "Retype %.30s@%.128s's new password: ", 1129 authctxt->server_user, host); 1130 retype = read_passphrase(prompt, 0); 1131 if (strcmp(password, retype) != 0) { 1132 freezero(password, strlen(password)); 1133 logit("Mismatch; try again, EOF to quit."); 1134 password = NULL; 1135 } 1136 freezero(retype, strlen(retype)); 1137 } 1138 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1139 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1140 (r = sshpkt_send(ssh)) != 0) 1141 goto out; 1142 1143 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1144 &input_userauth_passwd_changereq); 1145 r = 0; 1146 out: 1147 if (password) 1148 freezero(password, strlen(password)); 1149 free(info); 1150 free(lang); 1151 return r; 1152 } 1153 1154 /* 1155 * Select an algorithm for publickey signatures. 1156 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1157 * 1158 * Call with ssh==NULL to ignore server-sig-algs extension list and 1159 * only attempt with the key's base signature type. 1160 */ 1161 static char * 1162 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1163 { 1164 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1165 const char *server_sig_algs; 1166 1167 /* 1168 * The signature algorithm will only differ from the key algorithm 1169 * for RSA keys/certs and when the server advertises support for 1170 * newer (SHA2) algorithms. 1171 */ 1172 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1173 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1174 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1175 /* Filter base key signature alg against our configuration */ 1176 return match_list(sshkey_ssh_name(key), 1177 options.pubkey_accepted_algos, NULL); 1178 } 1179 1180 /* 1181 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1182 * fails to advertise it via SSH2_MSG_EXT_INFO. 1183 */ 1184 server_sig_algs = ssh->kex->server_sig_algs; 1185 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1186 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1187 1188 /* 1189 * For RSA keys/certs, since these might have a different sig type: 1190 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1191 * that also appears in the supported signature algorithms list from 1192 * the server. 1193 */ 1194 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1195 while ((cp = strsep(&allowed, ",")) != NULL) { 1196 if (sshkey_type_from_name(cp) != key->type) 1197 continue; 1198 tmp = match_list(sshkey_sigalg_by_name(cp), 1199 server_sig_algs, NULL); 1200 if (tmp != NULL) 1201 alg = xstrdup(cp); 1202 free(tmp); 1203 if (alg != NULL) 1204 break; 1205 } 1206 free(oallowed); 1207 return alg; 1208 } 1209 1210 static int 1211 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1212 const u_char *data, size_t datalen, u_int compat, const char *alg) 1213 { 1214 struct sshkey *sign_key = NULL, *prv = NULL; 1215 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1216 struct notifier_ctx *notifier = NULL; 1217 char *fp = NULL, *pin = NULL, *prompt = NULL; 1218 1219 *sigp = NULL; 1220 *lenp = 0; 1221 1222 /* The agent supports this key. */ 1223 if (id->key != NULL && id->agent_fd != -1) { 1224 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1225 data, datalen, alg, compat); 1226 } 1227 1228 /* 1229 * We have already loaded the private key or the private key is 1230 * stored in external hardware. 1231 */ 1232 if (id->key != NULL && 1233 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1234 sign_key = id->key; 1235 is_agent = 1; 1236 } else { 1237 /* Load the private key from the file. */ 1238 if ((prv = load_identity_file(id)) == NULL) 1239 return SSH_ERR_KEY_NOT_FOUND; 1240 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1241 error_f("private key %s contents do not match public", 1242 id->filename); 1243 r = SSH_ERR_KEY_NOT_FOUND; 1244 goto out; 1245 } 1246 sign_key = prv; 1247 } 1248 retry_pin: 1249 /* Prompt for touch for non-agent FIDO keys that request UP */ 1250 if (!is_agent && sshkey_is_sk(sign_key) && 1251 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1252 /* XXX should batch mode just skip these? */ 1253 if ((fp = sshkey_fingerprint(sign_key, 1254 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1255 fatal_f("fingerprint failed"); 1256 notifier = notify_start(options.batch_mode, 1257 "Confirm user presence for key %s %s", 1258 sshkey_type(sign_key), fp); 1259 free(fp); 1260 } 1261 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1262 alg, options.sk_provider, pin, compat)) != 0) { 1263 debug_fr(r, "sshkey_sign"); 1264 if (!retried && pin == NULL && !is_agent && 1265 sshkey_is_sk(sign_key) && 1266 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1267 notify_complete(notifier, NULL); 1268 notifier = NULL; 1269 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1270 sshkey_type(sign_key), id->filename); 1271 pin = read_passphrase(prompt, 0); 1272 retried = 1; 1273 goto retry_pin; 1274 } 1275 goto out; 1276 } 1277 1278 /* 1279 * PKCS#11 tokens may not support all signature algorithms, 1280 * so check what we get back. 1281 */ 1282 if (id->key != NULL && (id->key->flags & SSHKEY_FLAG_EXT) != 0 && 1283 (r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1284 debug_fr(r, "sshkey_check_sigtype"); 1285 goto out; 1286 } 1287 /* success */ 1288 r = 0; 1289 out: 1290 free(prompt); 1291 if (pin != NULL) 1292 freezero(pin, strlen(pin)); 1293 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1294 sshkey_free(prv); 1295 return r; 1296 } 1297 1298 static int 1299 id_filename_matches(Identity *id, Identity *private_id) 1300 { 1301 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1302 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1303 size_t i, slen; 1304 1305 if (strcmp(id->filename, private_id->filename) == 0) 1306 return 1; 1307 for (i = 0; suffixes[i]; i++) { 1308 slen = strlen(suffixes[i]); 1309 if (len > slen && plen == len - slen && 1310 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1311 memcmp(id->filename, private_id->filename, plen) == 0) 1312 return 1; 1313 } 1314 return 0; 1315 } 1316 1317 static int 1318 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1319 { 1320 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1321 struct sshbuf *b = NULL; 1322 Identity *private_id, *sign_id = NULL; 1323 u_char *signature = NULL; 1324 size_t slen = 0, skip = 0; 1325 int r, fallback_sigtype, sent = 0; 1326 char *alg = NULL, *fp = NULL; 1327 const char *loc = "", *method = "publickey"; 1328 int hostbound = 0; 1329 1330 /* prefer host-bound pubkey signatures if supported by server */ 1331 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1332 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1333 hostbound = 1; 1334 method = "publickey-hostbound-v00@openssh.com"; 1335 } 1336 1337 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1338 SSH_FP_DEFAULT)) == NULL) 1339 return 0; 1340 1341 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1342 1343 /* 1344 * If the key is an certificate, try to find a matching private key 1345 * and use it to complete the signature. 1346 * If no such private key exists, fall back to trying the certificate 1347 * key itself in case it has a private half already loaded. 1348 * This will try to set sign_id to the private key that will perform 1349 * the signature. 1350 */ 1351 if (id->agent_fd == -1 && sshkey_is_cert(id->key)) { 1352 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1353 if (sshkey_equal_public(id->key, private_id->key) && 1354 id->key->type != private_id->key->type) { 1355 sign_id = private_id; 1356 break; 1357 } 1358 } 1359 /* 1360 * Exact key matches are preferred, but also allow 1361 * filename matches for non-PKCS#11/agent keys that 1362 * didn't load public keys. This supports the case 1363 * of keeping just a private key file and public 1364 * certificate on disk. 1365 */ 1366 if (sign_id == NULL && 1367 !id->isprivate && id->agent_fd == -1 && 1368 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1369 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1370 if (private_id->key == NULL && 1371 id_filename_matches(id, private_id)) { 1372 sign_id = private_id; 1373 break; 1374 } 1375 } 1376 } 1377 if (sign_id != NULL) { 1378 debug2_f("using private key \"%s\"%s for " 1379 "certificate", sign_id->filename, 1380 sign_id->agent_fd != -1 ? " from agent" : ""); 1381 } else { 1382 debug_f("no separate private key for certificate " 1383 "\"%s\"", id->filename); 1384 } 1385 } 1386 1387 /* 1388 * If the above didn't select another identity to do the signing 1389 * then default to the one we started with. 1390 */ 1391 if (sign_id == NULL) 1392 sign_id = id; 1393 1394 /* assemble and sign data */ 1395 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1396 free(alg); 1397 slen = 0; 1398 signature = NULL; 1399 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1400 id->key)) == NULL) { 1401 error_f("no mutual signature supported"); 1402 goto out; 1403 } 1404 debug3_f("signing using %s %s", alg, fp); 1405 1406 sshbuf_free(b); 1407 if ((b = sshbuf_new()) == NULL) 1408 fatal_f("sshbuf_new failed"); 1409 if (ssh->compat & SSH_OLD_SESSIONID) { 1410 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1411 fatal_fr(r, "sshbuf_putb"); 1412 } else { 1413 if ((r = sshbuf_put_stringb(b, 1414 ssh->kex->session_id)) != 0) 1415 fatal_fr(r, "sshbuf_put_stringb"); 1416 } 1417 skip = sshbuf_len(b); 1418 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1419 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1420 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1421 (r = sshbuf_put_cstring(b, method)) != 0 || 1422 (r = sshbuf_put_u8(b, 1)) != 0 || 1423 (r = sshbuf_put_cstring(b, alg)) != 0 || 1424 (r = sshkey_puts(id->key, b)) != 0) { 1425 fatal_fr(r, "assemble signed data"); 1426 } 1427 if (hostbound) { 1428 if (ssh->kex->initial_hostkey == NULL) { 1429 fatal_f("internal error: initial hostkey " 1430 "not recorded"); 1431 } 1432 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1433 fatal_fr(r, "assemble %s hostkey", method); 1434 } 1435 /* generate signature */ 1436 r = identity_sign(sign_id, &signature, &slen, 1437 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1438 if (r == 0) 1439 break; 1440 else if (r == SSH_ERR_KEY_NOT_FOUND) 1441 goto out; /* soft failure */ 1442 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1443 !fallback_sigtype) { 1444 if (sign_id->agent_fd != -1) 1445 loc = "agent "; 1446 else if (sign_id->key != NULL && 1447 (sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1448 loc = "token "; 1449 logit("%skey %s %s returned incorrect signature type", 1450 loc, sshkey_type(id->key), fp); 1451 continue; 1452 } 1453 error_fr(r, "signing failed for %s \"%s\"%s", 1454 sshkey_type(sign_id->key), sign_id->filename, 1455 id->agent_fd != -1 ? " from agent" : ""); 1456 goto out; 1457 } 1458 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1459 fatal_f("no signature"); 1460 1461 /* append signature */ 1462 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1463 fatal_fr(r, "append signature"); 1464 1465 #ifdef DEBUG_PK 1466 sshbuf_dump(b, stderr); 1467 #endif 1468 /* skip session id and packet type */ 1469 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1470 fatal_fr(r, "consume"); 1471 1472 /* put remaining data from buffer into packet */ 1473 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1474 (r = sshpkt_putb(ssh, b)) != 0 || 1475 (r = sshpkt_send(ssh)) != 0) 1476 fatal_fr(r, "enqueue request"); 1477 1478 /* success */ 1479 sent = 1; 1480 1481 out: 1482 free(fp); 1483 free(alg); 1484 sshbuf_free(b); 1485 freezero(signature, slen); 1486 return sent; 1487 } 1488 1489 static int 1490 send_pubkey_test(struct ssh *ssh, Identity *id) 1491 { 1492 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1493 u_char *blob = NULL; 1494 char *alg = NULL; 1495 size_t bloblen; 1496 u_int have_sig = 0; 1497 int sent = 0, r; 1498 1499 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1500 debug_f("no mutual signature algorithm"); 1501 goto out; 1502 } 1503 1504 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1505 /* we cannot handle this key */ 1506 debug3_f("cannot handle key"); 1507 goto out; 1508 } 1509 /* register callback for USERAUTH_PK_OK message */ 1510 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1511 1512 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1513 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1514 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1515 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1516 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1517 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1518 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1519 (r = sshpkt_send(ssh)) != 0) 1520 fatal_fr(r, "send packet"); 1521 sent = 1; 1522 1523 out: 1524 free(alg); 1525 free(blob); 1526 return sent; 1527 } 1528 1529 static struct sshkey * 1530 load_identity_file(Identity *id) 1531 { 1532 struct sshkey *private = NULL; 1533 char prompt[300], *passphrase, *comment; 1534 int r, quit = 0, i; 1535 struct stat st; 1536 1537 if (stat(id->filename, &st) == -1) { 1538 do_log2(id->userprovided ? 1539 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1540 "no such identity: %s: %s", id->filename, strerror(errno)); 1541 return NULL; 1542 } 1543 snprintf(prompt, sizeof prompt, 1544 "Enter passphrase for key '%.100s': ", id->filename); 1545 for (i = 0; i <= options.number_of_password_prompts; i++) { 1546 if (i == 0) 1547 passphrase = ""; 1548 else { 1549 passphrase = read_passphrase(prompt, 0); 1550 if (*passphrase == '\0') { 1551 debug2("no passphrase given, try next key"); 1552 free(passphrase); 1553 break; 1554 } 1555 } 1556 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1557 passphrase, &private, &comment))) { 1558 case 0: 1559 break; 1560 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1561 if (options.batch_mode) { 1562 quit = 1; 1563 break; 1564 } 1565 if (i != 0) 1566 debug2("bad passphrase given, try again..."); 1567 break; 1568 case SSH_ERR_SYSTEM_ERROR: 1569 if (errno == ENOENT) { 1570 debug2_r(r, "Load key \"%s\"", id->filename); 1571 quit = 1; 1572 break; 1573 } 1574 /* FALLTHROUGH */ 1575 default: 1576 error_r(r, "Load key \"%s\"", id->filename); 1577 quit = 1; 1578 break; 1579 } 1580 if (private != NULL && sshkey_is_sk(private) && 1581 options.sk_provider == NULL) { 1582 debug("key \"%s\" is an authenticator-hosted key, " 1583 "but no provider specified", id->filename); 1584 sshkey_free(private); 1585 private = NULL; 1586 quit = 1; 1587 } 1588 if (!quit && (r = sshkey_check_rsa_length(private, 1589 options.required_rsa_size)) != 0) { 1590 debug_fr(r, "Skipping key %s", id->filename); 1591 sshkey_free(private); 1592 private = NULL; 1593 quit = 1; 1594 } 1595 if (!quit && private != NULL && id->agent_fd == -1 && 1596 !(id->key && id->isprivate)) 1597 maybe_add_key_to_agent(id->filename, private, comment, 1598 passphrase); 1599 if (i > 0) 1600 freezero(passphrase, strlen(passphrase)); 1601 free(comment); 1602 if (private != NULL || quit) 1603 break; 1604 } 1605 return private; 1606 } 1607 1608 static int 1609 key_type_allowed(struct sshkey *key, const char *allowlist) 1610 { 1611 if (match_pattern_list(sshkey_ssh_name(key), allowlist, 0) == 1) 1612 return 1; 1613 1614 /* RSA keys/certs might be allowed by alternate signature types */ 1615 switch (key->type) { 1616 case KEY_RSA: 1617 if (match_pattern_list("rsa-sha2-512", allowlist, 0) == 1) 1618 return 1; 1619 if (match_pattern_list("rsa-sha2-256", allowlist, 0) == 1) 1620 return 1; 1621 break; 1622 case KEY_RSA_CERT: 1623 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1624 allowlist, 0) == 1) 1625 return 1; 1626 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1627 allowlist, 0) == 1) 1628 return 1; 1629 break; 1630 } 1631 return 0; 1632 } 1633 1634 static int 1635 key_type_allowed_by_config(struct sshkey *key) 1636 { 1637 return key_type_allowed(key, options.pubkey_accepted_algos); 1638 } 1639 1640 /* obtain a list of keys from the agent */ 1641 static int 1642 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1643 struct ssh_identitylist **idlistp) 1644 { 1645 int r, agent_fd; 1646 struct ssh_identitylist *idlist; 1647 1648 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1649 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1650 debug_fr(r, "ssh_get_authentication_socket"); 1651 return r; 1652 } 1653 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1654 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1655 debug_f("bound agent to hostkey"); 1656 else 1657 debug2_fr(r, "ssh_agent_bind_hostkey"); 1658 1659 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1660 debug_fr(r, "ssh_fetch_identitylist"); 1661 close(agent_fd); 1662 return r; 1663 } 1664 /* success */ 1665 *agent_fdp = agent_fd; 1666 *idlistp = idlist; 1667 debug_f("agent returned %zu keys", idlist->nkeys); 1668 return 0; 1669 } 1670 1671 /* 1672 * try keys in the following order: 1673 * 1. certificates listed in the config file 1674 * 2. other input certificates 1675 * 3. agent keys that are found in the config file 1676 * 4. other agent keys 1677 * 5. keys that are only listed in the config file 1678 */ 1679 static void 1680 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1681 { 1682 struct identity *id, *id2, *tmp; 1683 struct idlist agent, files, *preferred; 1684 struct sshkey *key; 1685 int disallowed, agent_fd = -1, i, r, found; 1686 size_t j; 1687 struct ssh_identitylist *idlist; 1688 char *cp, *ident; 1689 1690 TAILQ_INIT(&agent); /* keys from the agent */ 1691 TAILQ_INIT(&files); /* keys from the config file */ 1692 preferred = &authctxt->keys; 1693 TAILQ_INIT(preferred); /* preferred order of keys */ 1694 1695 /* list of keys stored in the filesystem and PKCS#11 */ 1696 for (i = 0; i < options.num_identity_files; i++) { 1697 key = options.identity_keys[i]; 1698 if (key && key->cert && 1699 key->cert->type != SSH2_CERT_TYPE_USER) { 1700 debug_f("ignoring certificate %s: not a user " 1701 "certificate", options.identity_files[i]); 1702 continue; 1703 } 1704 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1705 debug_f("ignoring authenticator-hosted key %s as no " 1706 "SecurityKeyProvider has been specified", 1707 options.identity_files[i]); 1708 continue; 1709 } 1710 options.identity_keys[i] = NULL; 1711 id = xcalloc(1, sizeof(*id)); 1712 id->agent_fd = -1; 1713 id->key = key; 1714 id->filename = xstrdup(options.identity_files[i]); 1715 id->userprovided = options.identity_file_userprovided[i]; 1716 TAILQ_INSERT_TAIL(&files, id, next); 1717 } 1718 /* list of certificates specified by user */ 1719 for (i = 0; i < options.num_certificate_files; i++) { 1720 key = options.certificates[i]; 1721 if (!sshkey_is_cert(key) || key->cert == NULL || 1722 key->cert->type != SSH2_CERT_TYPE_USER) { 1723 debug_f("ignoring certificate %s: not a user " 1724 "certificate", options.identity_files[i]); 1725 continue; 1726 } 1727 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1728 debug_f("ignoring authenticator-hosted key " 1729 "certificate %s as no " 1730 "SecurityKeyProvider has been specified", 1731 options.identity_files[i]); 1732 continue; 1733 } 1734 id = xcalloc(1, sizeof(*id)); 1735 id->agent_fd = -1; 1736 id->key = key; 1737 id->filename = xstrdup(options.certificate_files[i]); 1738 id->userprovided = options.certificate_file_userprovided[i]; 1739 TAILQ_INSERT_TAIL(preferred, id, next); 1740 } 1741 /* list of keys supported by the agent */ 1742 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1743 for (j = 0; j < idlist->nkeys; j++) { 1744 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1745 options.required_rsa_size)) != 0) { 1746 debug_fr(r, "ignoring %s agent key", 1747 sshkey_ssh_name(idlist->keys[j])); 1748 continue; 1749 } 1750 found = 0; 1751 TAILQ_FOREACH(id, &files, next) { 1752 /* 1753 * agent keys from the config file are 1754 * preferred 1755 */ 1756 if (sshkey_equal(idlist->keys[j], id->key)) { 1757 TAILQ_REMOVE(&files, id, next); 1758 TAILQ_INSERT_TAIL(preferred, id, next); 1759 id->agent_fd = agent_fd; 1760 found = 1; 1761 break; 1762 } 1763 } 1764 if (!found && !options.identities_only) { 1765 id = xcalloc(1, sizeof(*id)); 1766 /* XXX "steals" key/comment from idlist */ 1767 id->key = idlist->keys[j]; 1768 id->filename = idlist->comments[j]; 1769 idlist->keys[j] = NULL; 1770 idlist->comments[j] = NULL; 1771 id->agent_fd = agent_fd; 1772 TAILQ_INSERT_TAIL(&agent, id, next); 1773 } 1774 } 1775 ssh_free_identitylist(idlist); 1776 /* append remaining agent keys */ 1777 TAILQ_CONCAT(preferred, &agent, next); 1778 authctxt->agent_fd = agent_fd; 1779 } 1780 /* Prefer PKCS11 keys that are explicitly listed */ 1781 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1782 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1783 continue; 1784 found = 0; 1785 TAILQ_FOREACH(id2, &files, next) { 1786 if (id2->key == NULL || 1787 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1788 continue; 1789 if (sshkey_equal(id->key, id2->key)) { 1790 TAILQ_REMOVE(&files, id, next); 1791 TAILQ_INSERT_TAIL(preferred, id, next); 1792 found = 1; 1793 break; 1794 } 1795 } 1796 /* If IdentitiesOnly set and key not found then don't use it */ 1797 if (!found && options.identities_only) { 1798 TAILQ_REMOVE(&files, id, next); 1799 freezero(id, sizeof(*id)); 1800 } 1801 } 1802 /* append remaining keys from the config file */ 1803 TAILQ_CONCAT(preferred, &files, next); 1804 /* finally, filter by PubkeyAcceptedAlgorithms */ 1805 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1806 disallowed = 0; 1807 cp = NULL; 1808 if (id->key == NULL) 1809 continue; 1810 if (!key_type_allowed_by_config(id->key)) { 1811 debug("Skipping %s key %s - corresponding algorithm " 1812 "not in PubkeyAcceptedAlgorithms", 1813 sshkey_ssh_name(id->key), id->filename); 1814 disallowed = 1; 1815 } else if (ssh->kex->server_sig_algs != NULL && 1816 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1817 debug("Skipping %s key %s - corresponding algorithm " 1818 "not supported by server", 1819 sshkey_ssh_name(id->key), id->filename); 1820 disallowed = 1; 1821 } 1822 free(cp); 1823 if (!disallowed) 1824 continue; 1825 /* remove key */ 1826 TAILQ_REMOVE(preferred, id, next); 1827 sshkey_free(id->key); 1828 free(id->filename); 1829 freezero(id, sizeof(*id)); 1830 } 1831 /* List the keys we plan on using */ 1832 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1833 ident = format_identity(id); 1834 debug("Will attempt key: %s", ident); 1835 free(ident); 1836 } 1837 debug2_f("done"); 1838 } 1839 1840 static void 1841 pubkey_cleanup(struct ssh *ssh) 1842 { 1843 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1844 Identity *id; 1845 1846 if (authctxt->agent_fd != -1) { 1847 ssh_close_authentication_socket(authctxt->agent_fd); 1848 authctxt->agent_fd = -1; 1849 } 1850 for (id = TAILQ_FIRST(&authctxt->keys); id; 1851 id = TAILQ_FIRST(&authctxt->keys)) { 1852 TAILQ_REMOVE(&authctxt->keys, id, next); 1853 sshkey_free(id->key); 1854 free(id->filename); 1855 free(id); 1856 } 1857 } 1858 1859 static void 1860 pubkey_reset(Authctxt *authctxt) 1861 { 1862 Identity *id; 1863 1864 TAILQ_FOREACH(id, &authctxt->keys, next) 1865 id->tried = 0; 1866 } 1867 1868 static int 1869 userauth_pubkey(struct ssh *ssh) 1870 { 1871 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1872 Identity *id; 1873 int sent = 0; 1874 char *ident; 1875 static int prepared; 1876 1877 if (!prepared) { 1878 pubkey_prepare(ssh, authctxt); 1879 prepared = 1; 1880 } 1881 1882 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1883 if (id->tried++) 1884 return (0); 1885 /* move key to the end of the queue */ 1886 TAILQ_REMOVE(&authctxt->keys, id, next); 1887 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1888 /* 1889 * send a test message if we have the public key. for 1890 * encrypted keys we cannot do this and have to load the 1891 * private key instead 1892 */ 1893 if (id->key != NULL) { 1894 ident = format_identity(id); 1895 debug("Offering public key: %s", ident); 1896 free(ident); 1897 sent = send_pubkey_test(ssh, id); 1898 } else { 1899 debug("Trying private key: %s", id->filename); 1900 id->key = load_identity_file(id); 1901 if (id->key != NULL) { 1902 id->isprivate = 1; 1903 sent = sign_and_send_pubkey(ssh, id); 1904 sshkey_free(id->key); 1905 id->key = NULL; 1906 id->isprivate = 0; 1907 } 1908 } 1909 if (sent) 1910 return (sent); 1911 } 1912 return (0); 1913 } 1914 1915 /* 1916 * Send userauth request message specifying keyboard-interactive method. 1917 */ 1918 static int 1919 userauth_kbdint(struct ssh *ssh) 1920 { 1921 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1922 int r; 1923 1924 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1925 return 0; 1926 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1927 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1928 debug3("userauth_kbdint: disable: no info_req_seen"); 1929 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1930 return 0; 1931 } 1932 1933 debug2("userauth_kbdint"); 1934 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1935 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1936 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1937 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1938 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1939 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1940 options.kbd_interactive_devices : "")) != 0 || 1941 (r = sshpkt_send(ssh)) != 0) 1942 fatal_fr(r, "send packet"); 1943 1944 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1945 return 1; 1946 } 1947 1948 /* 1949 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1950 */ 1951 static int 1952 input_userauth_info_req(int type, uint32_t seq, struct ssh *ssh) 1953 { 1954 Authctxt *authctxt = ssh->authctxt; 1955 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1956 char *display_prompt = NULL, *response = NULL; 1957 u_char echo = 0; 1958 u_int num_prompts, i; 1959 int r, addnl; 1960 size_t len; 1961 1962 debug2_f("entering"); 1963 1964 if (authctxt == NULL) 1965 fatal_f("no authentication context"); 1966 1967 authctxt->info_req_seen = 1; 1968 1969 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1970 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1971 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1972 goto out; 1973 if ((len = strlen(name)) > 0) { 1974 addnl = name[len] != '\n'; 1975 fmprintf(stderr, "%s%s", name, addnl ? "\n" : ""); 1976 } 1977 if ((len = strlen(inst)) > 0) { 1978 addnl = inst[len] != '\n'; 1979 fmprintf(stderr, "%s%s", inst, addnl ? "\n" : ""); 1980 } 1981 1982 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1983 goto out; 1984 /* 1985 * Begin to build info response packet based on prompts requested. 1986 * We commit to providing the correct number of responses, so if 1987 * further on we run into a problem that prevents this, we have to 1988 * be sure and clean this up and send a correct error response. 1989 */ 1990 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1991 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1992 goto out; 1993 1994 debug2_f("num_prompts %d", num_prompts); 1995 for (i = 0; i < num_prompts; i++) { 1996 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1997 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1998 goto out; 1999 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 2000 authctxt->server_user, options.host_key_alias ? 2001 options.host_key_alias : authctxt->host, prompt) == -1) 2002 fatal_f("asmprintf failed"); 2003 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2004 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2005 goto out; 2006 freezero(response, strlen(response)); 2007 free(prompt); 2008 free(display_prompt); 2009 display_prompt = response = prompt = NULL; 2010 } 2011 /* done with parsing incoming message. */ 2012 if ((r = sshpkt_get_end(ssh)) != 0 || 2013 (r = sshpkt_add_padding(ssh, 64)) != 0) 2014 goto out; 2015 r = sshpkt_send(ssh); 2016 out: 2017 if (response) 2018 freezero(response, strlen(response)); 2019 free(prompt); 2020 free(display_prompt); 2021 free(name); 2022 free(inst); 2023 free(lang); 2024 return r; 2025 } 2026 2027 static int 2028 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2029 const u_char *data, size_t datalen) 2030 { 2031 struct sshbuf *b; 2032 struct stat st; 2033 pid_t pid; 2034 int r, to[2], from[2], status; 2035 int sock = ssh_packet_get_connection_in(ssh); 2036 u_char rversion = 0, version = 2; 2037 void (*osigchld)(int); 2038 2039 *sigp = NULL; 2040 *lenp = 0; 2041 2042 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2043 error_f("not installed: %s", strerror(errno)); 2044 return -1; 2045 } 2046 if (fflush(stdout) != 0) { 2047 error_f("fflush: %s", strerror(errno)); 2048 return -1; 2049 } 2050 if (pipe(to) == -1) { 2051 error_f("pipe: %s", strerror(errno)); 2052 return -1; 2053 } 2054 if (pipe(from) == -1) { 2055 error_f("pipe: %s", strerror(errno)); 2056 return -1; 2057 } 2058 if ((pid = fork()) == -1) { 2059 error_f("fork: %s", strerror(errno)); 2060 return -1; 2061 } 2062 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2063 if (pid == 0) { 2064 close(from[0]); 2065 if (dup2(from[1], STDOUT_FILENO) == -1) 2066 fatal_f("dup2: %s", strerror(errno)); 2067 close(to[1]); 2068 if (dup2(to[0], STDIN_FILENO) == -1) 2069 fatal_f("dup2: %s", strerror(errno)); 2070 close(from[1]); 2071 close(to[0]); 2072 2073 if (dup2(sock, STDERR_FILENO + 1) == -1) 2074 fatal_f("dup2: %s", strerror(errno)); 2075 sock = STDERR_FILENO + 1; 2076 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2077 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2078 closefrom(sock + 1); 2079 2080 debug3_f("[child] pid=%ld, exec %s", 2081 (long)getpid(), _PATH_SSH_KEY_SIGN); 2082 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2083 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2084 strerror(errno)); 2085 } 2086 close(from[1]); 2087 close(to[0]); 2088 sock = STDERR_FILENO + 1; 2089 2090 if ((b = sshbuf_new()) == NULL) 2091 fatal_f("sshbuf_new failed"); 2092 /* send # of sock, data to be signed */ 2093 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2094 (r = sshbuf_put_string(b, data, datalen)) != 0) 2095 fatal_fr(r, "buffer error"); 2096 if (ssh_msg_send(to[1], version, b) == -1) 2097 fatal_f("couldn't send request"); 2098 sshbuf_reset(b); 2099 r = ssh_msg_recv(from[0], b); 2100 close(from[0]); 2101 close(to[1]); 2102 if (r < 0) { 2103 error_f("no reply"); 2104 goto fail; 2105 } 2106 2107 errno = 0; 2108 while (waitpid(pid, &status, 0) == -1) { 2109 if (errno != EINTR) { 2110 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2111 goto fail; 2112 } 2113 } 2114 if (!WIFEXITED(status)) { 2115 error_f("exited abnormally"); 2116 goto fail; 2117 } 2118 if (WEXITSTATUS(status) != 0) { 2119 error_f("exited with status %d", WEXITSTATUS(status)); 2120 goto fail; 2121 } 2122 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2123 error_fr(r, "buffer error"); 2124 goto fail; 2125 } 2126 if (rversion != version) { 2127 error_f("bad version"); 2128 goto fail; 2129 } 2130 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2131 error_fr(r, "buffer error"); 2132 fail: 2133 ssh_signal(SIGCHLD, osigchld); 2134 sshbuf_free(b); 2135 return -1; 2136 } 2137 ssh_signal(SIGCHLD, osigchld); 2138 sshbuf_free(b); 2139 2140 return 0; 2141 } 2142 2143 static int 2144 userauth_hostbased(struct ssh *ssh) 2145 { 2146 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2147 struct sshkey *private = NULL; 2148 struct sshbuf *b = NULL; 2149 u_char *sig = NULL, *keyblob = NULL; 2150 char *fp = NULL, *chost = NULL, *lname = NULL; 2151 size_t siglen = 0, keylen = 0; 2152 int i, r, success = 0; 2153 2154 if (authctxt->ktypes == NULL) { 2155 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2156 authctxt->ktypes = authctxt->oktypes; 2157 } 2158 2159 /* 2160 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2161 * trying each hostkey that matches the type in turn. 2162 */ 2163 for (;;) { 2164 if (authctxt->active_ktype == NULL) 2165 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2166 if (authctxt->active_ktype == NULL || 2167 *authctxt->active_ktype == '\0') 2168 break; 2169 debug3_f("trying key type %s", authctxt->active_ktype); 2170 2171 /* check for a useful key */ 2172 private = NULL; 2173 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2174 if (authctxt->sensitive->keys[i] == NULL || 2175 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2176 continue; 2177 if (!sshkey_match_keyname_to_sigalgs( 2178 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2179 authctxt->active_ktype)) 2180 continue; 2181 /* we take and free the key */ 2182 private = authctxt->sensitive->keys[i]; 2183 authctxt->sensitive->keys[i] = NULL; 2184 break; 2185 } 2186 /* Found one */ 2187 if (private != NULL) 2188 break; 2189 /* No more keys of this type; advance */ 2190 authctxt->active_ktype = NULL; 2191 } 2192 if (private == NULL) { 2193 free(authctxt->oktypes); 2194 authctxt->oktypes = authctxt->ktypes = NULL; 2195 authctxt->active_ktype = NULL; 2196 debug("No more client hostkeys for hostbased authentication."); 2197 goto out; 2198 } 2199 2200 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2201 SSH_FP_DEFAULT)) == NULL) { 2202 error_f("sshkey_fingerprint failed"); 2203 goto out; 2204 } 2205 debug_f("trying hostkey %s %s using sigalg %s", 2206 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2207 2208 /* figure out a name for the client host */ 2209 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2210 if (lname == NULL) { 2211 error_f("cannot get local ipaddr/name"); 2212 goto out; 2213 } 2214 2215 /* XXX sshbuf_put_stringf? */ 2216 xasprintf(&chost, "%s.", lname); 2217 debug2_f("chost %s", chost); 2218 2219 /* construct data */ 2220 if ((b = sshbuf_new()) == NULL) { 2221 error_f("sshbuf_new failed"); 2222 goto out; 2223 } 2224 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2225 error_fr(r, "sshkey_to_blob"); 2226 goto out; 2227 } 2228 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2229 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2230 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2231 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2232 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2233 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2234 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2235 (r = sshbuf_put_cstring(b, chost)) != 0 || 2236 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2237 error_fr(r, "buffer error"); 2238 goto out; 2239 } 2240 2241 #ifdef DEBUG_PK 2242 sshbuf_dump(b, stderr); 2243 #endif 2244 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2245 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2246 error("sign using hostkey %s %s failed", 2247 sshkey_ssh_name(private), fp); 2248 goto out; 2249 } 2250 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2251 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2252 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2253 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2254 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2255 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2256 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2257 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2258 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2259 (r = sshpkt_send(ssh)) != 0) { 2260 error_fr(r, "packet error"); 2261 goto out; 2262 } 2263 success = 1; 2264 2265 out: 2266 if (sig != NULL) 2267 freezero(sig, siglen); 2268 free(keyblob); 2269 free(lname); 2270 free(fp); 2271 free(chost); 2272 sshkey_free(private); 2273 sshbuf_free(b); 2274 2275 return success; 2276 } 2277 2278 /* find auth method */ 2279 2280 /* 2281 * given auth method name, if configurable options permit this method fill 2282 * in auth_ident field and return true, otherwise return false. 2283 */ 2284 static int 2285 authmethod_is_enabled(Authmethod *method) 2286 { 2287 if (method == NULL) 2288 return 0; 2289 /* return false if options indicate this method is disabled */ 2290 if (method->enabled == NULL || *method->enabled == 0) 2291 return 0; 2292 /* return false if batch mode is enabled but method needs interactive mode */ 2293 if (method->batch_flag != NULL && *method->batch_flag != 0) 2294 return 0; 2295 return 1; 2296 } 2297 2298 static Authmethod * 2299 authmethod_lookup(const char *name) 2300 { 2301 Authmethod *method = NULL; 2302 if (name != NULL) 2303 for (method = authmethods; method->name != NULL; method++) 2304 if (strcmp(name, method->name) == 0) 2305 return method; 2306 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2307 return NULL; 2308 } 2309 2310 /* XXX internal state */ 2311 static Authmethod *current = NULL; 2312 static char *supported = NULL; 2313 static char *preferred = NULL; 2314 2315 /* 2316 * Given the authentication method list sent by the server, return the 2317 * next method we should try. If the server initially sends a nil list, 2318 * use a built-in default list. 2319 */ 2320 static Authmethod * 2321 authmethod_get(char *authlist) 2322 { 2323 char *name = NULL; 2324 u_int next; 2325 2326 /* Use a suitable default if we're passed a nil list. */ 2327 if (authlist == NULL || strlen(authlist) == 0) 2328 authlist = options.preferred_authentications; 2329 2330 if (supported == NULL || strcmp(authlist, supported) != 0) { 2331 debug3("start over, passed a different list %s", authlist); 2332 free(supported); 2333 supported = xstrdup(authlist); 2334 preferred = options.preferred_authentications; 2335 debug3("preferred %s", preferred); 2336 current = NULL; 2337 } else if (current != NULL && authmethod_is_enabled(current)) 2338 return current; 2339 2340 for (;;) { 2341 if ((name = match_list(preferred, supported, &next)) == NULL) { 2342 debug("No more authentication methods to try."); 2343 current = NULL; 2344 return NULL; 2345 } 2346 preferred += next; 2347 debug3("authmethod_lookup %s", name); 2348 debug3("remaining preferred: %s", preferred); 2349 if ((current = authmethod_lookup(name)) != NULL && 2350 authmethod_is_enabled(current)) { 2351 debug3("authmethod_is_enabled %s", name); 2352 debug("Next authentication method: %s", name); 2353 free(name); 2354 return current; 2355 } 2356 free(name); 2357 } 2358 } 2359 2360 static char * 2361 authmethods_get(void) 2362 { 2363 Authmethod *method = NULL; 2364 struct sshbuf *b; 2365 char *list; 2366 int r; 2367 2368 if ((b = sshbuf_new()) == NULL) 2369 fatal_f("sshbuf_new failed"); 2370 for (method = authmethods; method->name != NULL; method++) { 2371 if (authmethod_is_enabled(method)) { 2372 if ((r = sshbuf_putf(b, "%s%s", 2373 sshbuf_len(b) ? "," : "", method->name)) != 0) 2374 fatal_fr(r, "buffer error"); 2375 } 2376 } 2377 if ((list = sshbuf_dup_string(b)) == NULL) 2378 fatal_f("sshbuf_dup_string failed"); 2379 sshbuf_free(b); 2380 return list; 2381 } 2382