1 /* $OpenBSD: sshconnect2.c,v 1.372 2024/01/08 00:34:34 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <limits.h> 36 #include <netdb.h> 37 #include <stdio.h> 38 #include <string.h> 39 #include <stdarg.h> 40 #include <signal.h> 41 #include <pwd.h> 42 #include <unistd.h> 43 #include <vis.h> 44 45 #include "xmalloc.h" 46 #include "ssh.h" 47 #include "ssh2.h" 48 #include "sshbuf.h" 49 #include "packet.h" 50 #include "compat.h" 51 #include "cipher.h" 52 #include "sshkey.h" 53 #include "kex.h" 54 #include "sshconnect.h" 55 #include "authfile.h" 56 #include "dh.h" 57 #include "authfd.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "readconf.h" 61 #include "match.h" 62 #include "dispatch.h" 63 #include "canohost.h" 64 #include "msg.h" 65 #include "pathnames.h" 66 #include "uidswap.h" 67 #include "hostfile.h" 68 #include "ssherr.h" 69 #include "utf8.h" 70 #include "ssh-sk.h" 71 #include "sk-api.h" 72 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 77 /* import */ 78 extern char *client_version_string; 79 extern char *server_version_string; 80 extern Options options; 81 82 /* 83 * SSH2 key exchange 84 */ 85 86 static char *xxx_host; 87 static struct sockaddr *xxx_hostaddr; 88 static const struct ssh_conn_info *xxx_conn_info; 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 (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 99 xxx_conn_info) == -1) 100 fatal("Host key verification failed."); 101 return 0; 102 } 103 104 /* Returns the first item from a comma-separated algorithm list */ 105 static char * 106 first_alg(const char *algs) 107 { 108 char *ret, *cp; 109 110 ret = xstrdup(algs); 111 if ((cp = strchr(ret, ',')) != NULL) 112 *cp = '\0'; 113 return ret; 114 } 115 116 static char * 117 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 118 const struct ssh_conn_info *cinfo) 119 { 120 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 121 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 122 size_t maxlen; 123 struct hostkeys *hostkeys = NULL; 124 int ktype; 125 u_int i; 126 127 /* Find all hostkeys for this hostname */ 128 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 129 hostkeys = init_hostkeys(); 130 for (i = 0; i < options.num_user_hostfiles; i++) 131 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 132 for (i = 0; i < options.num_system_hostfiles; i++) { 133 load_hostkeys(hostkeys, hostname, 134 options.system_hostfiles[i], 0); 135 } 136 if (options.known_hosts_command != NULL) { 137 load_hostkeys_command(hostkeys, options.known_hosts_command, 138 "ORDER", cinfo, NULL, hostname); 139 } 140 /* 141 * If a plain public key exists that matches the type of the best 142 * preference HostkeyAlgorithms, then use the whole list as is. 143 * Note that we ignore whether the best preference algorithm is a 144 * certificate type, as sshconnect.c will downgrade certs to 145 * plain keys if necessary. 146 */ 147 best = first_alg(options.hostkeyalgorithms); 148 if (lookup_key_in_hostkeys_by_type(hostkeys, 149 sshkey_type_plain(sshkey_type_from_name(best)), 150 sshkey_ecdsa_nid_from_name(best), NULL)) { 151 debug3_f("have matching best-preference key type %s, " 152 "using HostkeyAlgorithms verbatim", best); 153 ret = xstrdup(options.hostkeyalgorithms); 154 goto out; 155 } 156 157 /* 158 * Otherwise, prefer the host key algorithms that match known keys 159 * while keeping the ordering of HostkeyAlgorithms as much as possible. 160 */ 161 oavail = avail = xstrdup(options.hostkeyalgorithms); 162 maxlen = strlen(avail) + 1; 163 first = xmalloc(maxlen); 164 last = xmalloc(maxlen); 165 *first = *last = '\0'; 166 167 #define ALG_APPEND(to, from) \ 168 do { \ 169 if (*to != '\0') \ 170 strlcat(to, ",", maxlen); \ 171 strlcat(to, from, maxlen); \ 172 } while (0) 173 174 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 175 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 176 fatal_f("unknown alg %s", alg); 177 /* 178 * If we have a @cert-authority marker in known_hosts then 179 * prefer all certificate algorithms. 180 */ 181 if (sshkey_type_is_cert(ktype) && 182 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 183 ALG_APPEND(first, alg); 184 continue; 185 } 186 /* If the key appears in known_hosts then prefer it */ 187 if (lookup_key_in_hostkeys_by_type(hostkeys, 188 sshkey_type_plain(ktype), 189 sshkey_ecdsa_nid_from_name(alg), NULL)) { 190 ALG_APPEND(first, alg); 191 continue; 192 } 193 /* Otherwise, put it last */ 194 ALG_APPEND(last, alg); 195 } 196 #undef ALG_APPEND 197 xasprintf(&ret, "%s%s%s", first, 198 (*first == '\0' || *last == '\0') ? "" : ",", last); 199 if (*first != '\0') 200 debug3_f("prefer hostkeyalgs: %s", first); 201 else 202 debug3_f("no algorithms matched; accept original"); 203 out: 204 free(best); 205 free(first); 206 free(last); 207 free(hostname); 208 free(oavail); 209 free_hostkeys(hostkeys); 210 211 return ret; 212 } 213 214 void 215 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 216 const struct ssh_conn_info *cinfo) 217 { 218 char *myproposal[PROPOSAL_MAX]; 219 char *all_key, *hkalgs = NULL; 220 int r, use_known_hosts_order = 0; 221 222 xxx_host = host; 223 xxx_hostaddr = hostaddr; 224 xxx_conn_info = cinfo; 225 226 if (options.rekey_limit || options.rekey_interval) 227 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 228 options.rekey_interval); 229 230 /* 231 * If the user has not specified HostkeyAlgorithms, or has only 232 * appended or removed algorithms from that list then prefer algorithms 233 * that are in the list that are supported by known_hosts keys. 234 */ 235 if (options.hostkeyalgorithms == NULL || 236 options.hostkeyalgorithms[0] == '-' || 237 options.hostkeyalgorithms[0] == '+') 238 use_known_hosts_order = 1; 239 240 /* Expand or fill in HostkeyAlgorithms */ 241 all_key = sshkey_alg_list(0, 0, 1, ','); 242 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 243 kex_default_pk_alg(), all_key)) != 0) 244 fatal_fr(r, "kex_assemble_namelist"); 245 free(all_key); 246 247 if (use_known_hosts_order) 248 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 249 250 kex_proposal_populate_entries(ssh, myproposal, 251 options.kex_algorithms, options.ciphers, options.macs, 252 compression_alg_list(options.compression), 253 hkalgs ? hkalgs : options.hostkeyalgorithms); 254 255 free(hkalgs); 256 257 /* start key exchange */ 258 if ((r = kex_setup(ssh, myproposal)) != 0) 259 fatal_r(r, "kex_setup"); 260 #ifdef WITH_OPENSSL 261 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 262 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 263 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 264 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 265 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 266 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 267 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 268 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 269 #endif 270 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 271 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 272 ssh->kex->verify_host_key=&verify_host_key_callback; 273 274 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 275 kex_proposal_free_entries(myproposal); 276 277 #ifdef DEBUG_KEXDH 278 /* send 1st encrypted/maced/compressed message */ 279 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 280 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 281 (r = sshpkt_send(ssh)) != 0 || 282 (r = ssh_packet_write_wait(ssh)) != 0) 283 fatal_fr(r, "send packet"); 284 #endif 285 } 286 287 /* 288 * Authenticate user 289 */ 290 291 typedef struct cauthctxt Authctxt; 292 typedef struct cauthmethod Authmethod; 293 typedef struct identity Identity; 294 typedef struct idlist Idlist; 295 296 struct identity { 297 TAILQ_ENTRY(identity) next; 298 int agent_fd; /* >=0 if agent supports key */ 299 struct sshkey *key; /* public/private key */ 300 char *filename; /* comment for agent-only keys */ 301 int tried; 302 int isprivate; /* key points to the private key */ 303 int userprovided; 304 }; 305 TAILQ_HEAD(idlist, identity); 306 307 struct cauthctxt { 308 const char *server_user; 309 const char *local_user; 310 const char *host; 311 const char *service; 312 struct cauthmethod *method; 313 sig_atomic_t success; 314 char *authlist; 315 #ifdef GSSAPI 316 /* gssapi */ 317 gss_OID_set gss_supported_mechs; 318 u_int mech_tried; 319 #endif 320 /* pubkey */ 321 struct idlist keys; 322 int agent_fd; 323 /* hostbased */ 324 Sensitive *sensitive; 325 char *oktypes, *ktypes; 326 const char *active_ktype; 327 /* kbd-interactive */ 328 int info_req_seen; 329 int attempt_kbdint; 330 /* password */ 331 int attempt_passwd; 332 /* generic */ 333 void *methoddata; 334 }; 335 336 struct cauthmethod { 337 char *name; /* string to compare against server's list */ 338 int (*userauth)(struct ssh *ssh); 339 void (*cleanup)(struct ssh *ssh); 340 int *enabled; /* flag in option struct that enables method */ 341 int *batch_flag; /* flag in option struct that disables method */ 342 }; 343 344 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 345 static int input_userauth_success(int, u_int32_t, struct ssh *); 346 static int input_userauth_failure(int, u_int32_t, struct ssh *); 347 static int input_userauth_banner(int, u_int32_t, struct ssh *); 348 static int input_userauth_error(int, u_int32_t, struct ssh *); 349 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 350 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 351 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 352 353 static int userauth_none(struct ssh *); 354 static int userauth_pubkey(struct ssh *); 355 static int userauth_passwd(struct ssh *); 356 static int userauth_kbdint(struct ssh *); 357 static int userauth_hostbased(struct ssh *); 358 359 #ifdef GSSAPI 360 static int userauth_gssapi(struct ssh *); 361 static void userauth_gssapi_cleanup(struct ssh *); 362 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 363 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 364 static int input_gssapi_error(int, u_int32_t, struct ssh *); 365 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 366 #endif 367 368 void userauth(struct ssh *, char *); 369 370 static void pubkey_cleanup(struct ssh *); 371 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 372 static void pubkey_prepare(struct ssh *, Authctxt *); 373 static void pubkey_reset(Authctxt *); 374 static struct sshkey *load_identity_file(Identity *); 375 376 static Authmethod *authmethod_get(char *authlist); 377 static Authmethod *authmethod_lookup(const char *name); 378 static char *authmethods_get(void); 379 380 Authmethod authmethods[] = { 381 #ifdef GSSAPI 382 {"gssapi-with-mic", 383 userauth_gssapi, 384 userauth_gssapi_cleanup, 385 &options.gss_authentication, 386 NULL}, 387 #endif 388 {"hostbased", 389 userauth_hostbased, 390 NULL, 391 &options.hostbased_authentication, 392 NULL}, 393 {"publickey", 394 userauth_pubkey, 395 NULL, 396 &options.pubkey_authentication, 397 NULL}, 398 {"keyboard-interactive", 399 userauth_kbdint, 400 NULL, 401 &options.kbd_interactive_authentication, 402 &options.batch_mode}, 403 {"password", 404 userauth_passwd, 405 NULL, 406 &options.password_authentication, 407 &options.batch_mode}, 408 {"none", 409 userauth_none, 410 NULL, 411 NULL, 412 NULL}, 413 {NULL, NULL, NULL, NULL, NULL} 414 }; 415 416 void 417 ssh_userauth2(struct ssh *ssh, const char *local_user, 418 const char *server_user, char *host, Sensitive *sensitive) 419 { 420 Authctxt authctxt; 421 int r; 422 423 if (options.preferred_authentications == NULL) 424 options.preferred_authentications = authmethods_get(); 425 426 /* setup authentication context */ 427 memset(&authctxt, 0, sizeof(authctxt)); 428 authctxt.server_user = server_user; 429 authctxt.local_user = local_user; 430 authctxt.host = host; 431 authctxt.service = "ssh-connection"; /* service name */ 432 authctxt.success = 0; 433 authctxt.method = authmethod_lookup("none"); 434 authctxt.authlist = NULL; 435 authctxt.methoddata = NULL; 436 authctxt.sensitive = sensitive; 437 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 438 authctxt.info_req_seen = 0; 439 authctxt.attempt_kbdint = 0; 440 authctxt.attempt_passwd = 0; 441 #if GSSAPI 442 authctxt.gss_supported_mechs = NULL; 443 authctxt.mech_tried = 0; 444 #endif 445 authctxt.agent_fd = -1; 446 if (authctxt.method == NULL) 447 fatal_f("internal error: cannot send userauth none request"); 448 449 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 450 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 451 (r = sshpkt_send(ssh)) != 0) 452 fatal_fr(r, "send packet"); 453 454 ssh->authctxt = &authctxt; 455 ssh_dispatch_init(ssh, &input_userauth_error); 456 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 457 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 458 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 459 pubkey_cleanup(ssh); 460 #ifdef GSSAPI 461 if (authctxt.gss_supported_mechs != NULL) { 462 u_int ms; 463 464 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 465 authctxt.gss_supported_mechs = NULL; 466 } 467 #endif 468 ssh->authctxt = NULL; 469 470 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 471 472 if (!authctxt.success) 473 fatal("Authentication failed."); 474 if (ssh_packet_connection_is_on_socket(ssh)) { 475 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 476 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 477 authctxt.method->name); 478 } else { 479 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 480 authctxt.method->name); 481 } 482 } 483 484 static int 485 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 486 { 487 int r; 488 489 if (ssh_packet_remaining(ssh) > 0) { 490 char *reply; 491 492 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 493 goto out; 494 debug2("service_accept: %s", reply); 495 free(reply); 496 } else { 497 debug2("buggy server: service_accept w/o service"); 498 } 499 if ((r = sshpkt_get_end(ssh)) != 0) 500 goto out; 501 debug("SSH2_MSG_SERVICE_ACCEPT received"); 502 503 /* initial userauth request */ 504 userauth_none(ssh); 505 506 /* accept EXT_INFO at any time during userauth */ 507 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 508 &kex_input_ext_info : &input_userauth_error); 509 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 510 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 511 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 512 r = 0; 513 out: 514 return r; 515 } 516 517 void 518 userauth(struct ssh *ssh, char *authlist) 519 { 520 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 521 522 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 523 authctxt->method->cleanup(ssh); 524 525 free(authctxt->methoddata); 526 authctxt->methoddata = NULL; 527 if (authlist == NULL) { 528 authlist = authctxt->authlist; 529 } else { 530 free(authctxt->authlist); 531 authctxt->authlist = authlist; 532 } 533 for (;;) { 534 Authmethod *method = authmethod_get(authlist); 535 if (method == NULL) 536 fatal("%s@%s: Permission denied (%s).", 537 authctxt->server_user, authctxt->host, authlist); 538 authctxt->method = method; 539 540 /* reset the per method handler */ 541 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 542 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 543 544 /* and try new method */ 545 if (method->userauth(ssh) != 0) { 546 debug2("we sent a %s packet, wait for reply", method->name); 547 break; 548 } else { 549 debug2("we did not send a packet, disable method"); 550 method->enabled = NULL; 551 } 552 } 553 } 554 555 static int 556 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 557 { 558 fatal_f("bad message during authentication: type %d", type); 559 return 0; 560 } 561 562 static int 563 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 564 { 565 char *msg = NULL; 566 size_t len; 567 int r; 568 569 debug3_f("entering"); 570 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 571 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 572 goto out; 573 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 574 fmprintf(stderr, "%s", msg); 575 r = 0; 576 out: 577 free(msg); 578 return r; 579 } 580 581 static int 582 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 583 { 584 Authctxt *authctxt = ssh->authctxt; 585 586 if (authctxt == NULL) 587 fatal_f("no authentication context"); 588 free(authctxt->authlist); 589 authctxt->authlist = NULL; 590 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 591 authctxt->method->cleanup(ssh); 592 free(authctxt->methoddata); 593 authctxt->methoddata = NULL; 594 authctxt->success = 1; /* break out */ 595 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 596 return 0; 597 } 598 599 #if 0 600 static int 601 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 602 { 603 Authctxt *authctxt = ssh->authctxt; 604 605 if (authctxt == NULL) 606 fatal_f("no authentication context"); 607 608 fatal("Unexpected authentication success during %s.", 609 authctxt->method->name); 610 return 0; 611 } 612 #endif 613 614 static int 615 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 616 { 617 Authctxt *authctxt = ssh->authctxt; 618 char *authlist = NULL; 619 u_char partial; 620 621 if (authctxt == NULL) 622 fatal("input_userauth_failure: no authentication context"); 623 624 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 625 sshpkt_get_u8(ssh, &partial) != 0 || 626 sshpkt_get_end(ssh) != 0) 627 goto out; 628 629 if (partial != 0) { 630 verbose("Authenticated using \"%s\" with partial success.", 631 authctxt->method->name); 632 /* reset state */ 633 pubkey_reset(authctxt); 634 } 635 debug("Authentications that can continue: %s", authlist); 636 637 userauth(ssh, authlist); 638 authlist = NULL; 639 out: 640 free(authlist); 641 return 0; 642 } 643 644 /* 645 * Format an identity for logging including filename, key type, fingerprint 646 * and location (agent, etc.). Caller must free. 647 */ 648 static char * 649 format_identity(Identity *id) 650 { 651 char *fp = NULL, *ret = NULL; 652 const char *note = ""; 653 654 if (id->key != NULL) { 655 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 656 SSH_FP_DEFAULT); 657 } 658 if (id->key) { 659 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 660 note = " token"; 661 else if (sshkey_is_sk(id->key)) 662 note = " authenticator"; 663 } 664 xasprintf(&ret, "%s %s%s%s%s%s%s", 665 id->filename, 666 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 667 fp ? fp : "", 668 id->userprovided ? " explicit" : "", note, 669 id->agent_fd != -1 ? " agent" : ""); 670 free(fp); 671 return ret; 672 } 673 674 static int 675 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 676 { 677 Authctxt *authctxt = ssh->authctxt; 678 struct sshkey *key = NULL; 679 Identity *id = NULL; 680 int pktype, found = 0, sent = 0; 681 size_t blen; 682 char *pkalg = NULL, *fp = NULL, *ident = NULL; 683 u_char *pkblob = NULL; 684 int r; 685 686 if (authctxt == NULL) 687 fatal("input_userauth_pk_ok: no authentication context"); 688 689 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 690 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 691 (r = sshpkt_get_end(ssh)) != 0) 692 goto done; 693 694 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 695 debug_f("server sent unknown pkalg %s", pkalg); 696 goto done; 697 } 698 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 699 debug_r(r, "no key from blob. pkalg %s", pkalg); 700 goto done; 701 } 702 if (key->type != pktype) { 703 error("input_userauth_pk_ok: type mismatch " 704 "for decoded key (received %d, expected %d)", 705 key->type, pktype); 706 goto done; 707 } 708 709 /* 710 * search keys in the reverse order, because last candidate has been 711 * moved to the end of the queue. this also avoids confusion by 712 * duplicate keys 713 */ 714 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 715 if (sshkey_equal(key, id->key)) { 716 found = 1; 717 break; 718 } 719 } 720 if (!found || id == NULL) { 721 fp = sshkey_fingerprint(key, options.fingerprint_hash, 722 SSH_FP_DEFAULT); 723 error_f("server replied with unknown key: %s %s", 724 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 725 goto done; 726 } 727 ident = format_identity(id); 728 debug("Server accepts key: %s", ident); 729 sent = sign_and_send_pubkey(ssh, id); 730 r = 0; 731 done: 732 sshkey_free(key); 733 free(ident); 734 free(fp); 735 free(pkalg); 736 free(pkblob); 737 738 /* try another method if we did not send a packet */ 739 if (r == 0 && sent == 0) 740 userauth(ssh, NULL); 741 return r; 742 } 743 744 #ifdef GSSAPI 745 static int 746 userauth_gssapi(struct ssh *ssh) 747 { 748 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 749 Gssctxt *gssctxt = NULL; 750 OM_uint32 min; 751 int r, ok = 0; 752 gss_OID mech = NULL; 753 754 /* Try one GSSAPI method at a time, rather than sending them all at 755 * once. */ 756 757 if (authctxt->gss_supported_mechs == NULL) 758 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 759 760 /* Check to see whether the mechanism is usable before we offer it */ 761 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 762 !ok) { 763 mech = &authctxt->gss_supported_mechs-> 764 elements[authctxt->mech_tried]; 765 /* My DER encoding requires length<128 */ 766 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 767 mech, authctxt->host)) { 768 ok = 1; /* Mechanism works */ 769 } else { 770 authctxt->mech_tried++; 771 } 772 } 773 774 if (!ok || mech == NULL) 775 return 0; 776 777 authctxt->methoddata=(void *)gssctxt; 778 779 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 780 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 781 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 782 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 783 (r = sshpkt_put_u32(ssh, 1)) != 0 || 784 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 785 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 786 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 787 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 788 (r = sshpkt_send(ssh)) != 0) 789 fatal_fr(r, "send packet"); 790 791 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 792 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 793 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 794 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 795 796 authctxt->mech_tried++; /* Move along to next candidate */ 797 798 return 1; 799 } 800 801 static void 802 userauth_gssapi_cleanup(struct ssh *ssh) 803 { 804 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 805 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 806 807 ssh_gssapi_delete_ctx(&gssctxt); 808 authctxt->methoddata = NULL; 809 } 810 811 static OM_uint32 812 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 813 { 814 Authctxt *authctxt = ssh->authctxt; 815 Gssctxt *gssctxt = authctxt->methoddata; 816 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 817 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 818 gss_buffer_desc gssbuf; 819 OM_uint32 status, ms, flags; 820 int r; 821 822 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 823 recv_tok, &send_tok, &flags); 824 825 if (send_tok.length > 0) { 826 u_char type = GSS_ERROR(status) ? 827 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 828 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 829 830 if ((r = sshpkt_start(ssh, type)) != 0 || 831 (r = sshpkt_put_string(ssh, send_tok.value, 832 send_tok.length)) != 0 || 833 (r = sshpkt_send(ssh)) != 0) 834 fatal_fr(r, "send %u packet", type); 835 836 gss_release_buffer(&ms, &send_tok); 837 } 838 839 if (status == GSS_S_COMPLETE) { 840 /* send either complete or MIC, depending on mechanism */ 841 if (!(flags & GSS_C_INTEG_FLAG)) { 842 if ((r = sshpkt_start(ssh, 843 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 844 (r = sshpkt_send(ssh)) != 0) 845 fatal_fr(r, "send completion"); 846 } else { 847 struct sshbuf *b; 848 849 if ((b = sshbuf_new()) == NULL) 850 fatal_f("sshbuf_new failed"); 851 ssh_gssapi_buildmic(b, authctxt->server_user, 852 authctxt->service, "gssapi-with-mic", 853 ssh->kex->session_id); 854 855 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 856 fatal_f("sshbuf_mutable_ptr failed"); 857 gssbuf.length = sshbuf_len(b); 858 859 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 860 861 if (!GSS_ERROR(status)) { 862 if ((r = sshpkt_start(ssh, 863 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 864 (r = sshpkt_put_string(ssh, mic.value, 865 mic.length)) != 0 || 866 (r = sshpkt_send(ssh)) != 0) 867 fatal_fr(r, "send MIC"); 868 } 869 870 sshbuf_free(b); 871 gss_release_buffer(&ms, &mic); 872 } 873 } 874 875 return status; 876 } 877 878 static int 879 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 880 { 881 Authctxt *authctxt = ssh->authctxt; 882 Gssctxt *gssctxt; 883 size_t oidlen; 884 u_char *oidv = NULL; 885 int r; 886 887 if (authctxt == NULL) 888 fatal("input_gssapi_response: no authentication context"); 889 gssctxt = authctxt->methoddata; 890 891 /* Setup our OID */ 892 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 893 goto done; 894 895 if (oidlen <= 2 || 896 oidv[0] != SSH_GSS_OIDTYPE || 897 oidv[1] != oidlen - 2) { 898 debug("Badly encoded mechanism OID received"); 899 userauth(ssh, NULL); 900 goto ok; 901 } 902 903 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 904 fatal("Server returned different OID than expected"); 905 906 if ((r = sshpkt_get_end(ssh)) != 0) 907 goto done; 908 909 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 910 /* Start again with next method on list */ 911 debug("Trying to start again"); 912 userauth(ssh, NULL); 913 goto ok; 914 } 915 ok: 916 r = 0; 917 done: 918 free(oidv); 919 return r; 920 } 921 922 static int 923 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 924 { 925 Authctxt *authctxt = ssh->authctxt; 926 gss_buffer_desc recv_tok; 927 u_char *p = NULL; 928 size_t len; 929 OM_uint32 status; 930 int r; 931 932 if (authctxt == NULL) 933 fatal("input_gssapi_response: no authentication context"); 934 935 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 936 (r = sshpkt_get_end(ssh)) != 0) 937 goto out; 938 939 recv_tok.value = p; 940 recv_tok.length = len; 941 status = process_gssapi_token(ssh, &recv_tok); 942 943 /* Start again with the next method in the list */ 944 if (GSS_ERROR(status)) { 945 userauth(ssh, NULL); 946 /* ok */ 947 } 948 r = 0; 949 out: 950 free(p); 951 return r; 952 } 953 954 static int 955 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 956 { 957 Authctxt *authctxt = ssh->authctxt; 958 Gssctxt *gssctxt; 959 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 960 gss_buffer_desc recv_tok; 961 OM_uint32 ms; 962 u_char *p = NULL; 963 size_t len; 964 int r; 965 966 if (authctxt == NULL) 967 fatal("input_gssapi_response: no authentication context"); 968 gssctxt = authctxt->methoddata; 969 970 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 971 (r = sshpkt_get_end(ssh)) != 0) { 972 free(p); 973 return r; 974 } 975 976 /* Stick it into GSSAPI and see what it says */ 977 recv_tok.value = p; 978 recv_tok.length = len; 979 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 980 &recv_tok, &send_tok, NULL); 981 free(p); 982 gss_release_buffer(&ms, &send_tok); 983 984 /* Server will be returning a failed packet after this one */ 985 return 0; 986 } 987 988 static int 989 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 990 { 991 char *msg = NULL; 992 char *lang = NULL; 993 int r; 994 995 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 996 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 997 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 998 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 999 goto out; 1000 r = sshpkt_get_end(ssh); 1001 debug("Server GSSAPI Error:\n%s", msg); 1002 out: 1003 free(msg); 1004 free(lang); 1005 return r; 1006 } 1007 #endif /* GSSAPI */ 1008 1009 static int 1010 userauth_none(struct ssh *ssh) 1011 { 1012 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1013 int r; 1014 1015 /* initial userauth request */ 1016 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1017 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1018 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1019 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1020 (r = sshpkt_send(ssh)) != 0) 1021 fatal_fr(r, "send packet"); 1022 return 1; 1023 } 1024 1025 static int 1026 userauth_passwd(struct ssh *ssh) 1027 { 1028 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1029 char *password, *prompt = NULL; 1030 const char *host = options.host_key_alias ? options.host_key_alias : 1031 authctxt->host; 1032 int r; 1033 1034 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1035 return 0; 1036 1037 if (authctxt->attempt_passwd != 1) 1038 error("Permission denied, please try again."); 1039 1040 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1041 password = read_passphrase(prompt, 0); 1042 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1043 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1044 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1045 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1046 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1047 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1048 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1049 (r = sshpkt_send(ssh)) != 0) 1050 fatal_fr(r, "send packet"); 1051 1052 free(prompt); 1053 if (password != NULL) 1054 freezero(password, strlen(password)); 1055 1056 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1057 &input_userauth_passwd_changereq); 1058 1059 return 1; 1060 } 1061 1062 /* 1063 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1064 */ 1065 static int 1066 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1067 { 1068 Authctxt *authctxt = ssh->authctxt; 1069 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1070 char prompt[256]; 1071 const char *host; 1072 int r; 1073 1074 debug2("input_userauth_passwd_changereq"); 1075 1076 if (authctxt == NULL) 1077 fatal("input_userauth_passwd_changereq: " 1078 "no authentication context"); 1079 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1080 1081 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1082 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1083 goto out; 1084 if (strlen(info) > 0) 1085 logit("%s", info); 1086 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1087 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1088 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1089 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1090 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1091 goto out; 1092 1093 snprintf(prompt, sizeof(prompt), 1094 "Enter %.30s@%.128s's old password: ", 1095 authctxt->server_user, host); 1096 password = read_passphrase(prompt, 0); 1097 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1098 goto out; 1099 1100 freezero(password, strlen(password)); 1101 password = NULL; 1102 while (password == NULL) { 1103 snprintf(prompt, sizeof(prompt), 1104 "Enter %.30s@%.128s's new password: ", 1105 authctxt->server_user, host); 1106 password = read_passphrase(prompt, RP_ALLOW_EOF); 1107 if (password == NULL) { 1108 /* bail out */ 1109 r = 0; 1110 goto out; 1111 } 1112 snprintf(prompt, sizeof(prompt), 1113 "Retype %.30s@%.128s's new password: ", 1114 authctxt->server_user, host); 1115 retype = read_passphrase(prompt, 0); 1116 if (strcmp(password, retype) != 0) { 1117 freezero(password, strlen(password)); 1118 logit("Mismatch; try again, EOF to quit."); 1119 password = NULL; 1120 } 1121 freezero(retype, strlen(retype)); 1122 } 1123 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1124 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1125 (r = sshpkt_send(ssh)) != 0) 1126 goto out; 1127 1128 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1129 &input_userauth_passwd_changereq); 1130 r = 0; 1131 out: 1132 if (password) 1133 freezero(password, strlen(password)); 1134 free(info); 1135 free(lang); 1136 return r; 1137 } 1138 1139 /* 1140 * Select an algorithm for publickey signatures. 1141 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1142 * 1143 * Call with ssh==NULL to ignore server-sig-algs extension list and 1144 * only attempt with the key's base signature type. 1145 */ 1146 static char * 1147 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1148 { 1149 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1150 const char *server_sig_algs; 1151 1152 /* 1153 * The signature algorithm will only differ from the key algorithm 1154 * for RSA keys/certs and when the server advertises support for 1155 * newer (SHA2) algorithms. 1156 */ 1157 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1158 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1159 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1160 /* Filter base key signature alg against our configuration */ 1161 return match_list(sshkey_ssh_name(key), 1162 options.pubkey_accepted_algos, NULL); 1163 } 1164 1165 /* 1166 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1167 * fails to advertise it via SSH2_MSG_EXT_INFO. 1168 */ 1169 server_sig_algs = ssh->kex->server_sig_algs; 1170 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1171 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1172 1173 /* 1174 * For RSA keys/certs, since these might have a different sig type: 1175 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1176 * that also appears in the supported signature algorithms list from 1177 * the server. 1178 */ 1179 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1180 while ((cp = strsep(&allowed, ",")) != NULL) { 1181 if (sshkey_type_from_name(cp) != key->type) 1182 continue; 1183 tmp = match_list(sshkey_sigalg_by_name(cp), 1184 server_sig_algs, NULL); 1185 if (tmp != NULL) 1186 alg = xstrdup(cp); 1187 free(tmp); 1188 if (alg != NULL) 1189 break; 1190 } 1191 free(oallowed); 1192 return alg; 1193 } 1194 1195 static int 1196 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1197 const u_char *data, size_t datalen, u_int compat, const char *alg) 1198 { 1199 struct sshkey *sign_key = NULL, *prv = NULL; 1200 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1201 struct notifier_ctx *notifier = NULL; 1202 char *fp = NULL, *pin = NULL, *prompt = NULL; 1203 1204 *sigp = NULL; 1205 *lenp = 0; 1206 1207 /* The agent supports this key. */ 1208 if (id->key != NULL && id->agent_fd != -1) { 1209 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1210 data, datalen, alg, compat); 1211 } 1212 1213 /* 1214 * We have already loaded the private key or the private key is 1215 * stored in external hardware. 1216 */ 1217 if (id->key != NULL && 1218 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1219 sign_key = id->key; 1220 is_agent = 1; 1221 } else { 1222 /* Load the private key from the file. */ 1223 if ((prv = load_identity_file(id)) == NULL) 1224 return SSH_ERR_KEY_NOT_FOUND; 1225 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1226 error_f("private key %s contents do not match public", 1227 id->filename); 1228 r = SSH_ERR_KEY_NOT_FOUND; 1229 goto out; 1230 } 1231 sign_key = prv; 1232 } 1233 retry_pin: 1234 /* Prompt for touch for non-agent FIDO keys that request UP */ 1235 if (!is_agent && sshkey_is_sk(sign_key) && 1236 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1237 /* XXX should batch mode just skip these? */ 1238 if ((fp = sshkey_fingerprint(sign_key, 1239 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1240 fatal_f("fingerprint failed"); 1241 notifier = notify_start(options.batch_mode, 1242 "Confirm user presence for key %s %s", 1243 sshkey_type(sign_key), fp); 1244 free(fp); 1245 } 1246 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1247 alg, options.sk_provider, pin, compat)) != 0) { 1248 debug_fr(r, "sshkey_sign"); 1249 if (!retried && pin == NULL && !is_agent && 1250 sshkey_is_sk(sign_key) && 1251 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1252 notify_complete(notifier, NULL); 1253 notifier = NULL; 1254 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1255 sshkey_type(sign_key), id->filename); 1256 pin = read_passphrase(prompt, 0); 1257 retried = 1; 1258 goto retry_pin; 1259 } 1260 goto out; 1261 } 1262 1263 /* 1264 * PKCS#11 tokens may not support all signature algorithms, 1265 * so check what we get back. 1266 */ 1267 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1268 debug_fr(r, "sshkey_check_sigtype"); 1269 goto out; 1270 } 1271 /* success */ 1272 r = 0; 1273 out: 1274 free(prompt); 1275 if (pin != NULL) 1276 freezero(pin, strlen(pin)); 1277 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1278 sshkey_free(prv); 1279 return r; 1280 } 1281 1282 static int 1283 id_filename_matches(Identity *id, Identity *private_id) 1284 { 1285 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1286 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1287 size_t i, slen; 1288 1289 if (strcmp(id->filename, private_id->filename) == 0) 1290 return 1; 1291 for (i = 0; suffixes[i]; i++) { 1292 slen = strlen(suffixes[i]); 1293 if (len > slen && plen == len - slen && 1294 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1295 memcmp(id->filename, private_id->filename, plen) == 0) 1296 return 1; 1297 } 1298 return 0; 1299 } 1300 1301 static int 1302 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1303 { 1304 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1305 struct sshbuf *b = NULL; 1306 Identity *private_id, *sign_id = NULL; 1307 u_char *signature = NULL; 1308 size_t slen = 0, skip = 0; 1309 int r, fallback_sigtype, sent = 0; 1310 char *alg = NULL, *fp = NULL; 1311 const char *loc = "", *method = "publickey"; 1312 int hostbound = 0; 1313 1314 /* prefer host-bound pubkey signatures if supported by server */ 1315 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1316 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1317 hostbound = 1; 1318 method = "publickey-hostbound-v00@openssh.com"; 1319 } 1320 1321 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1322 SSH_FP_DEFAULT)) == NULL) 1323 return 0; 1324 1325 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1326 1327 /* 1328 * If the key is an certificate, try to find a matching private key 1329 * and use it to complete the signature. 1330 * If no such private key exists, fall back to trying the certificate 1331 * key itself in case it has a private half already loaded. 1332 * This will try to set sign_id to the private key that will perform 1333 * the signature. 1334 */ 1335 if (sshkey_is_cert(id->key)) { 1336 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1337 if (sshkey_equal_public(id->key, private_id->key) && 1338 id->key->type != private_id->key->type) { 1339 sign_id = private_id; 1340 break; 1341 } 1342 } 1343 /* 1344 * Exact key matches are preferred, but also allow 1345 * filename matches for non-PKCS#11/agent keys that 1346 * didn't load public keys. This supports the case 1347 * of keeping just a private key file and public 1348 * certificate on disk. 1349 */ 1350 if (sign_id == NULL && 1351 !id->isprivate && id->agent_fd == -1 && 1352 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1353 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1354 if (private_id->key == NULL && 1355 id_filename_matches(id, private_id)) { 1356 sign_id = private_id; 1357 break; 1358 } 1359 } 1360 } 1361 if (sign_id != NULL) { 1362 debug2_f("using private key \"%s\"%s for " 1363 "certificate", sign_id->filename, 1364 sign_id->agent_fd != -1 ? " from agent" : ""); 1365 } else { 1366 debug_f("no separate private key for certificate " 1367 "\"%s\"", id->filename); 1368 } 1369 } 1370 1371 /* 1372 * If the above didn't select another identity to do the signing 1373 * then default to the one we started with. 1374 */ 1375 if (sign_id == NULL) 1376 sign_id = id; 1377 1378 /* assemble and sign data */ 1379 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1380 free(alg); 1381 slen = 0; 1382 signature = NULL; 1383 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1384 id->key)) == NULL) { 1385 error_f("no mutual signature supported"); 1386 goto out; 1387 } 1388 debug3_f("signing using %s %s", alg, fp); 1389 1390 sshbuf_free(b); 1391 if ((b = sshbuf_new()) == NULL) 1392 fatal_f("sshbuf_new failed"); 1393 if (ssh->compat & SSH_OLD_SESSIONID) { 1394 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1395 fatal_fr(r, "sshbuf_putb"); 1396 } else { 1397 if ((r = sshbuf_put_stringb(b, 1398 ssh->kex->session_id)) != 0) 1399 fatal_fr(r, "sshbuf_put_stringb"); 1400 } 1401 skip = sshbuf_len(b); 1402 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1403 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1404 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1405 (r = sshbuf_put_cstring(b, method)) != 0 || 1406 (r = sshbuf_put_u8(b, 1)) != 0 || 1407 (r = sshbuf_put_cstring(b, alg)) != 0 || 1408 (r = sshkey_puts(id->key, b)) != 0) { 1409 fatal_fr(r, "assemble signed data"); 1410 } 1411 if (hostbound) { 1412 if (ssh->kex->initial_hostkey == NULL) { 1413 fatal_f("internal error: initial hostkey " 1414 "not recorded"); 1415 } 1416 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1417 fatal_fr(r, "assemble %s hostkey", method); 1418 } 1419 /* generate signature */ 1420 r = identity_sign(sign_id, &signature, &slen, 1421 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1422 if (r == 0) 1423 break; 1424 else if (r == SSH_ERR_KEY_NOT_FOUND) 1425 goto out; /* soft failure */ 1426 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1427 !fallback_sigtype) { 1428 if (sign_id->agent_fd != -1) 1429 loc = "agent "; 1430 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1431 loc = "token "; 1432 logit("%skey %s %s returned incorrect signature type", 1433 loc, sshkey_type(id->key), fp); 1434 continue; 1435 } 1436 error_fr(r, "signing failed for %s \"%s\"%s", 1437 sshkey_type(sign_id->key), sign_id->filename, 1438 id->agent_fd != -1 ? " from agent" : ""); 1439 goto out; 1440 } 1441 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1442 fatal_f("no signature"); 1443 1444 /* append signature */ 1445 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1446 fatal_fr(r, "append signature"); 1447 1448 #ifdef DEBUG_PK 1449 sshbuf_dump(b, stderr); 1450 #endif 1451 /* skip session id and packet type */ 1452 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1453 fatal_fr(r, "consume"); 1454 1455 /* put remaining data from buffer into packet */ 1456 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1457 (r = sshpkt_putb(ssh, b)) != 0 || 1458 (r = sshpkt_send(ssh)) != 0) 1459 fatal_fr(r, "enqueue request"); 1460 1461 /* success */ 1462 sent = 1; 1463 1464 out: 1465 free(fp); 1466 free(alg); 1467 sshbuf_free(b); 1468 freezero(signature, slen); 1469 return sent; 1470 } 1471 1472 static int 1473 send_pubkey_test(struct ssh *ssh, Identity *id) 1474 { 1475 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1476 u_char *blob = NULL; 1477 char *alg = NULL; 1478 size_t bloblen; 1479 u_int have_sig = 0; 1480 int sent = 0, r; 1481 1482 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1483 debug_f("no mutual signature algorithm"); 1484 goto out; 1485 } 1486 1487 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1488 /* we cannot handle this key */ 1489 debug3_f("cannot handle key"); 1490 goto out; 1491 } 1492 /* register callback for USERAUTH_PK_OK message */ 1493 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1494 1495 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1496 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1497 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1498 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1499 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1500 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1501 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1502 (r = sshpkt_send(ssh)) != 0) 1503 fatal_fr(r, "send packet"); 1504 sent = 1; 1505 1506 out: 1507 free(alg); 1508 free(blob); 1509 return sent; 1510 } 1511 1512 static struct sshkey * 1513 load_identity_file(Identity *id) 1514 { 1515 struct sshkey *private = NULL; 1516 char prompt[300], *passphrase, *comment; 1517 int r, quit = 0, i; 1518 struct stat st; 1519 1520 if (stat(id->filename, &st) == -1) { 1521 do_log2(id->userprovided ? 1522 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1523 "no such identity: %s: %s", id->filename, strerror(errno)); 1524 return NULL; 1525 } 1526 snprintf(prompt, sizeof prompt, 1527 "Enter passphrase for key '%.100s': ", id->filename); 1528 for (i = 0; i <= options.number_of_password_prompts; i++) { 1529 if (i == 0) 1530 passphrase = ""; 1531 else { 1532 passphrase = read_passphrase(prompt, 0); 1533 if (*passphrase == '\0') { 1534 debug2("no passphrase given, try next key"); 1535 free(passphrase); 1536 break; 1537 } 1538 } 1539 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1540 passphrase, &private, &comment))) { 1541 case 0: 1542 break; 1543 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1544 if (options.batch_mode) { 1545 quit = 1; 1546 break; 1547 } 1548 if (i != 0) 1549 debug2("bad passphrase given, try again..."); 1550 break; 1551 case SSH_ERR_SYSTEM_ERROR: 1552 if (errno == ENOENT) { 1553 debug2_r(r, "Load key \"%s\"", id->filename); 1554 quit = 1; 1555 break; 1556 } 1557 /* FALLTHROUGH */ 1558 default: 1559 error_r(r, "Load key \"%s\"", id->filename); 1560 quit = 1; 1561 break; 1562 } 1563 if (private != NULL && sshkey_is_sk(private) && 1564 options.sk_provider == NULL) { 1565 debug("key \"%s\" is an authenticator-hosted key, " 1566 "but no provider specified", id->filename); 1567 sshkey_free(private); 1568 private = NULL; 1569 quit = 1; 1570 } 1571 if (!quit && (r = sshkey_check_rsa_length(private, 1572 options.required_rsa_size)) != 0) { 1573 debug_fr(r, "Skipping key %s", id->filename); 1574 sshkey_free(private); 1575 private = NULL; 1576 quit = 1; 1577 } 1578 if (!quit && private != NULL && id->agent_fd == -1 && 1579 !(id->key && id->isprivate)) 1580 maybe_add_key_to_agent(id->filename, private, comment, 1581 passphrase); 1582 if (i > 0) 1583 freezero(passphrase, strlen(passphrase)); 1584 free(comment); 1585 if (private != NULL || quit) 1586 break; 1587 } 1588 return private; 1589 } 1590 1591 static int 1592 key_type_allowed_by_config(struct sshkey *key) 1593 { 1594 if (match_pattern_list(sshkey_ssh_name(key), 1595 options.pubkey_accepted_algos, 0) == 1) 1596 return 1; 1597 1598 /* RSA keys/certs might be allowed by alternate signature types */ 1599 switch (key->type) { 1600 case KEY_RSA: 1601 if (match_pattern_list("rsa-sha2-512", 1602 options.pubkey_accepted_algos, 0) == 1) 1603 return 1; 1604 if (match_pattern_list("rsa-sha2-256", 1605 options.pubkey_accepted_algos, 0) == 1) 1606 return 1; 1607 break; 1608 case KEY_RSA_CERT: 1609 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1610 options.pubkey_accepted_algos, 0) == 1) 1611 return 1; 1612 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1613 options.pubkey_accepted_algos, 0) == 1) 1614 return 1; 1615 break; 1616 } 1617 return 0; 1618 } 1619 1620 /* obtain a list of keys from the agent */ 1621 static int 1622 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1623 struct ssh_identitylist **idlistp) 1624 { 1625 int r, agent_fd; 1626 struct ssh_identitylist *idlist; 1627 1628 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1629 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1630 debug_fr(r, "ssh_get_authentication_socket"); 1631 return r; 1632 } 1633 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1634 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1635 debug_f("bound agent to hostkey"); 1636 else 1637 debug2_fr(r, "ssh_agent_bind_hostkey"); 1638 1639 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1640 debug_fr(r, "ssh_fetch_identitylist"); 1641 close(agent_fd); 1642 return r; 1643 } 1644 /* success */ 1645 *agent_fdp = agent_fd; 1646 *idlistp = idlist; 1647 debug_f("agent returned %zu keys", idlist->nkeys); 1648 return 0; 1649 } 1650 1651 /* 1652 * try keys in the following order: 1653 * 1. certificates listed in the config file 1654 * 2. other input certificates 1655 * 3. agent keys that are found in the config file 1656 * 4. other agent keys 1657 * 5. keys that are only listed in the config file 1658 */ 1659 static void 1660 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1661 { 1662 struct identity *id, *id2, *tmp; 1663 struct idlist agent, files, *preferred; 1664 struct sshkey *key; 1665 int disallowed, agent_fd = -1, i, r, found; 1666 size_t j; 1667 struct ssh_identitylist *idlist; 1668 char *cp, *ident; 1669 1670 TAILQ_INIT(&agent); /* keys from the agent */ 1671 TAILQ_INIT(&files); /* keys from the config file */ 1672 preferred = &authctxt->keys; 1673 TAILQ_INIT(preferred); /* preferred order of keys */ 1674 1675 /* list of keys stored in the filesystem and PKCS#11 */ 1676 for (i = 0; i < options.num_identity_files; i++) { 1677 key = options.identity_keys[i]; 1678 if (key && key->cert && 1679 key->cert->type != SSH2_CERT_TYPE_USER) { 1680 debug_f("ignoring certificate %s: not a user " 1681 "certificate", options.identity_files[i]); 1682 continue; 1683 } 1684 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1685 debug_f("ignoring authenticator-hosted key %s as no " 1686 "SecurityKeyProvider has been specified", 1687 options.identity_files[i]); 1688 continue; 1689 } 1690 options.identity_keys[i] = NULL; 1691 id = xcalloc(1, sizeof(*id)); 1692 id->agent_fd = -1; 1693 id->key = key; 1694 id->filename = xstrdup(options.identity_files[i]); 1695 id->userprovided = options.identity_file_userprovided[i]; 1696 TAILQ_INSERT_TAIL(&files, id, next); 1697 } 1698 /* list of certificates specified by user */ 1699 for (i = 0; i < options.num_certificate_files; i++) { 1700 key = options.certificates[i]; 1701 if (!sshkey_is_cert(key) || key->cert == NULL || 1702 key->cert->type != SSH2_CERT_TYPE_USER) { 1703 debug_f("ignoring certificate %s: not a user " 1704 "certificate", options.identity_files[i]); 1705 continue; 1706 } 1707 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1708 debug_f("ignoring authenticator-hosted key " 1709 "certificate %s as no " 1710 "SecurityKeyProvider has been specified", 1711 options.identity_files[i]); 1712 continue; 1713 } 1714 id = xcalloc(1, sizeof(*id)); 1715 id->agent_fd = -1; 1716 id->key = key; 1717 id->filename = xstrdup(options.certificate_files[i]); 1718 id->userprovided = options.certificate_file_userprovided[i]; 1719 TAILQ_INSERT_TAIL(preferred, id, next); 1720 } 1721 /* list of keys supported by the agent */ 1722 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1723 for (j = 0; j < idlist->nkeys; j++) { 1724 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1725 options.required_rsa_size)) != 0) { 1726 debug_fr(r, "ignoring %s agent key", 1727 sshkey_ssh_name(idlist->keys[j])); 1728 continue; 1729 } 1730 found = 0; 1731 TAILQ_FOREACH(id, &files, next) { 1732 /* 1733 * agent keys from the config file are 1734 * preferred 1735 */ 1736 if (sshkey_equal(idlist->keys[j], id->key)) { 1737 TAILQ_REMOVE(&files, id, next); 1738 TAILQ_INSERT_TAIL(preferred, id, next); 1739 id->agent_fd = agent_fd; 1740 found = 1; 1741 break; 1742 } 1743 } 1744 if (!found && !options.identities_only) { 1745 id = xcalloc(1, sizeof(*id)); 1746 /* XXX "steals" key/comment from idlist */ 1747 id->key = idlist->keys[j]; 1748 id->filename = idlist->comments[j]; 1749 idlist->keys[j] = NULL; 1750 idlist->comments[j] = NULL; 1751 id->agent_fd = agent_fd; 1752 TAILQ_INSERT_TAIL(&agent, id, next); 1753 } 1754 } 1755 ssh_free_identitylist(idlist); 1756 /* append remaining agent keys */ 1757 TAILQ_CONCAT(preferred, &agent, next); 1758 authctxt->agent_fd = agent_fd; 1759 } 1760 /* Prefer PKCS11 keys that are explicitly listed */ 1761 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1762 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1763 continue; 1764 found = 0; 1765 TAILQ_FOREACH(id2, &files, next) { 1766 if (id2->key == NULL || 1767 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1768 continue; 1769 if (sshkey_equal(id->key, id2->key)) { 1770 TAILQ_REMOVE(&files, id, next); 1771 TAILQ_INSERT_TAIL(preferred, id, next); 1772 found = 1; 1773 break; 1774 } 1775 } 1776 /* If IdentitiesOnly set and key not found then don't use it */ 1777 if (!found && options.identities_only) { 1778 TAILQ_REMOVE(&files, id, next); 1779 freezero(id, sizeof(*id)); 1780 } 1781 } 1782 /* append remaining keys from the config file */ 1783 TAILQ_CONCAT(preferred, &files, next); 1784 /* finally, filter by PubkeyAcceptedAlgorithms */ 1785 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1786 disallowed = 0; 1787 cp = NULL; 1788 if (id->key == NULL) 1789 continue; 1790 if (!key_type_allowed_by_config(id->key)) { 1791 debug("Skipping %s key %s - corresponding algorithm " 1792 "not in PubkeyAcceptedAlgorithms", 1793 sshkey_ssh_name(id->key), id->filename); 1794 disallowed = 1; 1795 } else if (ssh->kex->server_sig_algs != NULL && 1796 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1797 debug("Skipping %s key %s - corresponding algorithm " 1798 "not supported by server", 1799 sshkey_ssh_name(id->key), id->filename); 1800 disallowed = 1; 1801 } 1802 free(cp); 1803 if (!disallowed) 1804 continue; 1805 /* remove key */ 1806 TAILQ_REMOVE(preferred, id, next); 1807 sshkey_free(id->key); 1808 free(id->filename); 1809 memset(id, 0, sizeof(*id)); 1810 } 1811 /* List the keys we plan on using */ 1812 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1813 ident = format_identity(id); 1814 debug("Will attempt key: %s", ident); 1815 free(ident); 1816 } 1817 debug2_f("done"); 1818 } 1819 1820 static void 1821 pubkey_cleanup(struct ssh *ssh) 1822 { 1823 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1824 Identity *id; 1825 1826 if (authctxt->agent_fd != -1) { 1827 ssh_close_authentication_socket(authctxt->agent_fd); 1828 authctxt->agent_fd = -1; 1829 } 1830 for (id = TAILQ_FIRST(&authctxt->keys); id; 1831 id = TAILQ_FIRST(&authctxt->keys)) { 1832 TAILQ_REMOVE(&authctxt->keys, id, next); 1833 sshkey_free(id->key); 1834 free(id->filename); 1835 free(id); 1836 } 1837 } 1838 1839 static void 1840 pubkey_reset(Authctxt *authctxt) 1841 { 1842 Identity *id; 1843 1844 TAILQ_FOREACH(id, &authctxt->keys, next) 1845 id->tried = 0; 1846 } 1847 1848 static int 1849 userauth_pubkey(struct ssh *ssh) 1850 { 1851 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1852 Identity *id; 1853 int sent = 0; 1854 char *ident; 1855 static int prepared; 1856 1857 if (!prepared) { 1858 pubkey_prepare(ssh, authctxt); 1859 prepared = 1; 1860 } 1861 1862 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1863 if (id->tried++) 1864 return (0); 1865 /* move key to the end of the queue */ 1866 TAILQ_REMOVE(&authctxt->keys, id, next); 1867 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1868 /* 1869 * send a test message if we have the public key. for 1870 * encrypted keys we cannot do this and have to load the 1871 * private key instead 1872 */ 1873 if (id->key != NULL) { 1874 ident = format_identity(id); 1875 debug("Offering public key: %s", ident); 1876 free(ident); 1877 sent = send_pubkey_test(ssh, id); 1878 } else { 1879 debug("Trying private key: %s", id->filename); 1880 id->key = load_identity_file(id); 1881 if (id->key != NULL) { 1882 if (id->key != NULL) { 1883 id->isprivate = 1; 1884 sent = sign_and_send_pubkey(ssh, id); 1885 } 1886 sshkey_free(id->key); 1887 id->key = NULL; 1888 id->isprivate = 0; 1889 } 1890 } 1891 if (sent) 1892 return (sent); 1893 } 1894 return (0); 1895 } 1896 1897 /* 1898 * Send userauth request message specifying keyboard-interactive method. 1899 */ 1900 static int 1901 userauth_kbdint(struct ssh *ssh) 1902 { 1903 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1904 int r; 1905 1906 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1907 return 0; 1908 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1909 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1910 debug3("userauth_kbdint: disable: no info_req_seen"); 1911 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1912 return 0; 1913 } 1914 1915 debug2("userauth_kbdint"); 1916 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1917 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1918 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1919 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1920 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1921 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1922 options.kbd_interactive_devices : "")) != 0 || 1923 (r = sshpkt_send(ssh)) != 0) 1924 fatal_fr(r, "send packet"); 1925 1926 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1927 return 1; 1928 } 1929 1930 /* 1931 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1932 */ 1933 static int 1934 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1935 { 1936 Authctxt *authctxt = ssh->authctxt; 1937 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1938 char *display_prompt = NULL, *response = NULL; 1939 u_char echo = 0; 1940 u_int num_prompts, i; 1941 int r; 1942 1943 debug2_f("entering"); 1944 1945 if (authctxt == NULL) 1946 fatal_f("no authentication context"); 1947 1948 authctxt->info_req_seen = 1; 1949 1950 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1951 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1952 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1953 goto out; 1954 if (strlen(name) > 0) 1955 logit("%s", name); 1956 if (strlen(inst) > 0) 1957 logit("%s", inst); 1958 1959 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1960 goto out; 1961 /* 1962 * Begin to build info response packet based on prompts requested. 1963 * We commit to providing the correct number of responses, so if 1964 * further on we run into a problem that prevents this, we have to 1965 * be sure and clean this up and send a correct error response. 1966 */ 1967 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1968 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1969 goto out; 1970 1971 debug2_f("num_prompts %d", num_prompts); 1972 for (i = 0; i < num_prompts; i++) { 1973 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1974 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1975 goto out; 1976 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1977 authctxt->server_user, options.host_key_alias ? 1978 options.host_key_alias : authctxt->host, prompt) == -1) 1979 fatal_f("asmprintf failed"); 1980 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1981 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1982 goto out; 1983 freezero(response, strlen(response)); 1984 free(prompt); 1985 free(display_prompt); 1986 display_prompt = response = prompt = NULL; 1987 } 1988 /* done with parsing incoming message. */ 1989 if ((r = sshpkt_get_end(ssh)) != 0 || 1990 (r = sshpkt_add_padding(ssh, 64)) != 0) 1991 goto out; 1992 r = sshpkt_send(ssh); 1993 out: 1994 if (response) 1995 freezero(response, strlen(response)); 1996 free(prompt); 1997 free(display_prompt); 1998 free(name); 1999 free(inst); 2000 free(lang); 2001 return r; 2002 } 2003 2004 static int 2005 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2006 const u_char *data, size_t datalen) 2007 { 2008 struct sshbuf *b; 2009 struct stat st; 2010 pid_t pid; 2011 int r, to[2], from[2], status; 2012 int sock = ssh_packet_get_connection_in(ssh); 2013 u_char rversion = 0, version = 2; 2014 void (*osigchld)(int); 2015 2016 *sigp = NULL; 2017 *lenp = 0; 2018 2019 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2020 error_f("not installed: %s", strerror(errno)); 2021 return -1; 2022 } 2023 if (fflush(stdout) != 0) { 2024 error_f("fflush: %s", strerror(errno)); 2025 return -1; 2026 } 2027 if (pipe(to) == -1) { 2028 error_f("pipe: %s", strerror(errno)); 2029 return -1; 2030 } 2031 if (pipe(from) == -1) { 2032 error_f("pipe: %s", strerror(errno)); 2033 return -1; 2034 } 2035 if ((pid = fork()) == -1) { 2036 error_f("fork: %s", strerror(errno)); 2037 return -1; 2038 } 2039 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2040 if (pid == 0) { 2041 close(from[0]); 2042 if (dup2(from[1], STDOUT_FILENO) == -1) 2043 fatal_f("dup2: %s", strerror(errno)); 2044 close(to[1]); 2045 if (dup2(to[0], STDIN_FILENO) == -1) 2046 fatal_f("dup2: %s", strerror(errno)); 2047 close(from[1]); 2048 close(to[0]); 2049 2050 if (dup2(sock, STDERR_FILENO + 1) == -1) 2051 fatal_f("dup2: %s", strerror(errno)); 2052 sock = STDERR_FILENO + 1; 2053 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2054 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2055 closefrom(sock + 1); 2056 2057 debug3_f("[child] pid=%ld, exec %s", 2058 (long)getpid(), _PATH_SSH_KEY_SIGN); 2059 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2060 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2061 strerror(errno)); 2062 } 2063 close(from[1]); 2064 close(to[0]); 2065 sock = STDERR_FILENO + 1; 2066 2067 if ((b = sshbuf_new()) == NULL) 2068 fatal_f("sshbuf_new failed"); 2069 /* send # of sock, data to be signed */ 2070 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2071 (r = sshbuf_put_string(b, data, datalen)) != 0) 2072 fatal_fr(r, "buffer error"); 2073 if (ssh_msg_send(to[1], version, b) == -1) 2074 fatal_f("couldn't send request"); 2075 sshbuf_reset(b); 2076 r = ssh_msg_recv(from[0], b); 2077 close(from[0]); 2078 close(to[1]); 2079 if (r < 0) { 2080 error_f("no reply"); 2081 goto fail; 2082 } 2083 2084 errno = 0; 2085 while (waitpid(pid, &status, 0) == -1) { 2086 if (errno != EINTR) { 2087 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2088 goto fail; 2089 } 2090 } 2091 if (!WIFEXITED(status)) { 2092 error_f("exited abnormally"); 2093 goto fail; 2094 } 2095 if (WEXITSTATUS(status) != 0) { 2096 error_f("exited with status %d", WEXITSTATUS(status)); 2097 goto fail; 2098 } 2099 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2100 error_fr(r, "buffer error"); 2101 goto fail; 2102 } 2103 if (rversion != version) { 2104 error_f("bad version"); 2105 goto fail; 2106 } 2107 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2108 error_fr(r, "buffer error"); 2109 fail: 2110 ssh_signal(SIGCHLD, osigchld); 2111 sshbuf_free(b); 2112 return -1; 2113 } 2114 ssh_signal(SIGCHLD, osigchld); 2115 sshbuf_free(b); 2116 2117 return 0; 2118 } 2119 2120 static int 2121 userauth_hostbased(struct ssh *ssh) 2122 { 2123 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2124 struct sshkey *private = NULL; 2125 struct sshbuf *b = NULL; 2126 u_char *sig = NULL, *keyblob = NULL; 2127 char *fp = NULL, *chost = NULL, *lname = NULL; 2128 size_t siglen = 0, keylen = 0; 2129 int i, r, success = 0; 2130 2131 if (authctxt->ktypes == NULL) { 2132 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2133 authctxt->ktypes = authctxt->oktypes; 2134 } 2135 2136 /* 2137 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2138 * trying each hostkey that matches the type in turn. 2139 */ 2140 for (;;) { 2141 if (authctxt->active_ktype == NULL) 2142 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2143 if (authctxt->active_ktype == NULL || 2144 *authctxt->active_ktype == '\0') 2145 break; 2146 debug3_f("trying key type %s", authctxt->active_ktype); 2147 2148 /* check for a useful key */ 2149 private = NULL; 2150 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2151 if (authctxt->sensitive->keys[i] == NULL || 2152 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2153 continue; 2154 if (!sshkey_match_keyname_to_sigalgs( 2155 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2156 authctxt->active_ktype)) 2157 continue; 2158 /* we take and free the key */ 2159 private = authctxt->sensitive->keys[i]; 2160 authctxt->sensitive->keys[i] = NULL; 2161 break; 2162 } 2163 /* Found one */ 2164 if (private != NULL) 2165 break; 2166 /* No more keys of this type; advance */ 2167 authctxt->active_ktype = NULL; 2168 } 2169 if (private == NULL) { 2170 free(authctxt->oktypes); 2171 authctxt->oktypes = authctxt->ktypes = NULL; 2172 authctxt->active_ktype = NULL; 2173 debug("No more client hostkeys for hostbased authentication."); 2174 goto out; 2175 } 2176 2177 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2178 SSH_FP_DEFAULT)) == NULL) { 2179 error_f("sshkey_fingerprint failed"); 2180 goto out; 2181 } 2182 debug_f("trying hostkey %s %s using sigalg %s", 2183 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2184 2185 /* figure out a name for the client host */ 2186 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2187 if (lname == NULL) { 2188 error_f("cannot get local ipaddr/name"); 2189 goto out; 2190 } 2191 2192 /* XXX sshbuf_put_stringf? */ 2193 xasprintf(&chost, "%s.", lname); 2194 debug2_f("chost %s", chost); 2195 2196 /* construct data */ 2197 if ((b = sshbuf_new()) == NULL) { 2198 error_f("sshbuf_new failed"); 2199 goto out; 2200 } 2201 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2202 error_fr(r, "sshkey_to_blob"); 2203 goto out; 2204 } 2205 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2206 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2207 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2208 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2209 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2210 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2211 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2212 (r = sshbuf_put_cstring(b, chost)) != 0 || 2213 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2214 error_fr(r, "buffer error"); 2215 goto out; 2216 } 2217 2218 #ifdef DEBUG_PK 2219 sshbuf_dump(b, stderr); 2220 #endif 2221 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2222 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2223 error("sign using hostkey %s %s failed", 2224 sshkey_ssh_name(private), fp); 2225 goto out; 2226 } 2227 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2228 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2229 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2230 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2231 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2232 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2233 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2234 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2235 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2236 (r = sshpkt_send(ssh)) != 0) { 2237 error_fr(r, "packet error"); 2238 goto out; 2239 } 2240 success = 1; 2241 2242 out: 2243 if (sig != NULL) 2244 freezero(sig, siglen); 2245 free(keyblob); 2246 free(lname); 2247 free(fp); 2248 free(chost); 2249 sshkey_free(private); 2250 sshbuf_free(b); 2251 2252 return success; 2253 } 2254 2255 /* find auth method */ 2256 2257 /* 2258 * given auth method name, if configurable options permit this method fill 2259 * in auth_ident field and return true, otherwise return false. 2260 */ 2261 static int 2262 authmethod_is_enabled(Authmethod *method) 2263 { 2264 if (method == NULL) 2265 return 0; 2266 /* return false if options indicate this method is disabled */ 2267 if (method->enabled == NULL || *method->enabled == 0) 2268 return 0; 2269 /* return false if batch mode is enabled but method needs interactive mode */ 2270 if (method->batch_flag != NULL && *method->batch_flag != 0) 2271 return 0; 2272 return 1; 2273 } 2274 2275 static Authmethod * 2276 authmethod_lookup(const char *name) 2277 { 2278 Authmethod *method = NULL; 2279 if (name != NULL) 2280 for (method = authmethods; method->name != NULL; method++) 2281 if (strcmp(name, method->name) == 0) 2282 return method; 2283 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2284 return NULL; 2285 } 2286 2287 /* XXX internal state */ 2288 static Authmethod *current = NULL; 2289 static char *supported = NULL; 2290 static char *preferred = NULL; 2291 2292 /* 2293 * Given the authentication method list sent by the server, return the 2294 * next method we should try. If the server initially sends a nil list, 2295 * use a built-in default list. 2296 */ 2297 static Authmethod * 2298 authmethod_get(char *authlist) 2299 { 2300 char *name = NULL; 2301 u_int next; 2302 2303 /* Use a suitable default if we're passed a nil list. */ 2304 if (authlist == NULL || strlen(authlist) == 0) 2305 authlist = options.preferred_authentications; 2306 2307 if (supported == NULL || strcmp(authlist, supported) != 0) { 2308 debug3("start over, passed a different list %s", authlist); 2309 free(supported); 2310 supported = xstrdup(authlist); 2311 preferred = options.preferred_authentications; 2312 debug3("preferred %s", preferred); 2313 current = NULL; 2314 } else if (current != NULL && authmethod_is_enabled(current)) 2315 return current; 2316 2317 for (;;) { 2318 if ((name = match_list(preferred, supported, &next)) == NULL) { 2319 debug("No more authentication methods to try."); 2320 current = NULL; 2321 return NULL; 2322 } 2323 preferred += next; 2324 debug3("authmethod_lookup %s", name); 2325 debug3("remaining preferred: %s", preferred); 2326 if ((current = authmethod_lookup(name)) != NULL && 2327 authmethod_is_enabled(current)) { 2328 debug3("authmethod_is_enabled %s", name); 2329 debug("Next authentication method: %s", name); 2330 free(name); 2331 return current; 2332 } 2333 free(name); 2334 } 2335 } 2336 2337 static char * 2338 authmethods_get(void) 2339 { 2340 Authmethod *method = NULL; 2341 struct sshbuf *b; 2342 char *list; 2343 int r; 2344 2345 if ((b = sshbuf_new()) == NULL) 2346 fatal_f("sshbuf_new failed"); 2347 for (method = authmethods; method->name != NULL; method++) { 2348 if (authmethod_is_enabled(method)) { 2349 if ((r = sshbuf_putf(b, "%s%s", 2350 sshbuf_len(b) ? "," : "", method->name)) != 0) 2351 fatal_fr(r, "buffer error"); 2352 } 2353 } 2354 if ((list = sshbuf_dup_string(b)) == NULL) 2355 fatal_f("sshbuf_dup_string failed"); 2356 sshbuf_free(b); 2357 return list; 2358 } 2359