1 /* $OpenBSD: sshconnect2.c,v 1.374 2024/09/02 12:13:56 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 Options options; 79 80 /* 81 * SSH2 key exchange 82 */ 83 84 static char *xxx_host; 85 static struct sockaddr *xxx_hostaddr; 86 static const struct ssh_conn_info *xxx_conn_info; 87 88 static int 89 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 90 { 91 int r; 92 93 if ((r = sshkey_check_rsa_length(hostkey, 94 options.required_rsa_size)) != 0) 95 fatal_r(r, "Bad server host key"); 96 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 97 xxx_conn_info) == -1) 98 fatal("Host key verification failed."); 99 return 0; 100 } 101 102 /* Returns the first item from a comma-separated algorithm list */ 103 static char * 104 first_alg(const char *algs) 105 { 106 char *ret, *cp; 107 108 ret = xstrdup(algs); 109 if ((cp = strchr(ret, ',')) != NULL) 110 *cp = '\0'; 111 return ret; 112 } 113 114 static char * 115 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 116 const struct ssh_conn_info *cinfo) 117 { 118 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 119 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 120 size_t maxlen; 121 struct hostkeys *hostkeys = NULL; 122 int ktype; 123 u_int i; 124 125 /* Find all hostkeys for this hostname */ 126 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 127 hostkeys = init_hostkeys(); 128 for (i = 0; i < options.num_user_hostfiles; i++) 129 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 130 for (i = 0; i < options.num_system_hostfiles; i++) { 131 load_hostkeys(hostkeys, hostname, 132 options.system_hostfiles[i], 0); 133 } 134 if (options.known_hosts_command != NULL) { 135 load_hostkeys_command(hostkeys, options.known_hosts_command, 136 "ORDER", cinfo, NULL, hostname); 137 } 138 /* 139 * If a plain public key exists that matches the type of the best 140 * preference HostkeyAlgorithms, then use the whole list as is. 141 * Note that we ignore whether the best preference algorithm is a 142 * certificate type, as sshconnect.c will downgrade certs to 143 * plain keys if necessary. 144 */ 145 best = first_alg(options.hostkeyalgorithms); 146 if (lookup_key_in_hostkeys_by_type(hostkeys, 147 sshkey_type_plain(sshkey_type_from_name(best)), 148 sshkey_ecdsa_nid_from_name(best), NULL)) { 149 debug3_f("have matching best-preference key type %s, " 150 "using HostkeyAlgorithms verbatim", best); 151 ret = xstrdup(options.hostkeyalgorithms); 152 goto out; 153 } 154 155 /* 156 * Otherwise, prefer the host key algorithms that match known keys 157 * while keeping the ordering of HostkeyAlgorithms as much as possible. 158 */ 159 oavail = avail = xstrdup(options.hostkeyalgorithms); 160 maxlen = strlen(avail) + 1; 161 first = xmalloc(maxlen); 162 last = xmalloc(maxlen); 163 *first = *last = '\0'; 164 165 #define ALG_APPEND(to, from) \ 166 do { \ 167 if (*to != '\0') \ 168 strlcat(to, ",", maxlen); \ 169 strlcat(to, from, maxlen); \ 170 } while (0) 171 172 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 173 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 174 fatal_f("unknown alg %s", alg); 175 /* 176 * If we have a @cert-authority marker in known_hosts then 177 * prefer all certificate algorithms. 178 */ 179 if (sshkey_type_is_cert(ktype) && 180 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 181 ALG_APPEND(first, alg); 182 continue; 183 } 184 /* If the key appears in known_hosts then prefer it */ 185 if (lookup_key_in_hostkeys_by_type(hostkeys, 186 sshkey_type_plain(ktype), 187 sshkey_ecdsa_nid_from_name(alg), NULL)) { 188 ALG_APPEND(first, alg); 189 continue; 190 } 191 /* Otherwise, put it last */ 192 ALG_APPEND(last, alg); 193 } 194 #undef ALG_APPEND 195 xasprintf(&ret, "%s%s%s", first, 196 (*first == '\0' || *last == '\0') ? "" : ",", last); 197 if (*first != '\0') 198 debug3_f("prefer hostkeyalgs: %s", first); 199 else 200 debug3_f("no algorithms matched; accept original"); 201 out: 202 free(best); 203 free(first); 204 free(last); 205 free(hostname); 206 free(oavail); 207 free_hostkeys(hostkeys); 208 209 return ret; 210 } 211 212 void 213 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 214 const struct ssh_conn_info *cinfo) 215 { 216 char *myproposal[PROPOSAL_MAX]; 217 char *all_key, *hkalgs = NULL; 218 int r, use_known_hosts_order = 0; 219 220 xxx_host = host; 221 xxx_hostaddr = hostaddr; 222 xxx_conn_info = cinfo; 223 224 if (options.rekey_limit || options.rekey_interval) 225 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 226 options.rekey_interval); 227 228 /* 229 * If the user has not specified HostkeyAlgorithms, or has only 230 * appended or removed algorithms from that list then prefer algorithms 231 * that are in the list that are supported by known_hosts keys. 232 */ 233 if (options.hostkeyalgorithms == NULL || 234 options.hostkeyalgorithms[0] == '-' || 235 options.hostkeyalgorithms[0] == '+') 236 use_known_hosts_order = 1; 237 238 /* Expand or fill in HostkeyAlgorithms */ 239 all_key = sshkey_alg_list(0, 0, 1, ','); 240 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 241 kex_default_pk_alg(), all_key)) != 0) 242 fatal_fr(r, "kex_assemble_namelist"); 243 free(all_key); 244 245 if (use_known_hosts_order) 246 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 247 248 kex_proposal_populate_entries(ssh, myproposal, 249 options.kex_algorithms, options.ciphers, options.macs, 250 compression_alg_list(options.compression), 251 hkalgs ? hkalgs : options.hostkeyalgorithms); 252 253 free(hkalgs); 254 255 /* start key exchange */ 256 if ((r = kex_setup(ssh, myproposal)) != 0) 257 fatal_r(r, "kex_setup"); 258 #ifdef WITH_OPENSSL 259 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 260 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 261 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 262 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 263 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 264 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 265 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 266 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 267 #endif 268 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 269 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 270 #ifdef WITH_MLKEM 271 ssh->kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_client; 272 #endif 273 ssh->kex->verify_host_key=&verify_host_key_callback; 274 275 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 276 kex_proposal_free_entries(myproposal); 277 278 #ifdef DEBUG_KEXDH 279 /* send 1st encrypted/maced/compressed message */ 280 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 281 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 282 (r = sshpkt_send(ssh)) != 0 || 283 (r = ssh_packet_write_wait(ssh)) != 0) 284 fatal_fr(r, "send packet"); 285 #endif 286 } 287 288 /* 289 * Authenticate user 290 */ 291 292 typedef struct cauthctxt Authctxt; 293 typedef struct cauthmethod Authmethod; 294 typedef struct identity Identity; 295 typedef struct idlist Idlist; 296 297 struct identity { 298 TAILQ_ENTRY(identity) next; 299 int agent_fd; /* >=0 if agent supports key */ 300 struct sshkey *key; /* public/private key */ 301 char *filename; /* comment for agent-only keys */ 302 int tried; 303 int isprivate; /* key points to the private key */ 304 int userprovided; 305 }; 306 TAILQ_HEAD(idlist, identity); 307 308 struct cauthctxt { 309 const char *server_user; 310 const char *local_user; 311 const char *host; 312 const char *service; 313 struct cauthmethod *method; 314 sig_atomic_t success; 315 char *authlist; 316 #ifdef GSSAPI 317 /* gssapi */ 318 gss_OID_set gss_supported_mechs; 319 u_int mech_tried; 320 #endif 321 /* pubkey */ 322 struct idlist keys; 323 int agent_fd; 324 /* hostbased */ 325 Sensitive *sensitive; 326 char *oktypes, *ktypes; 327 const char *active_ktype; 328 /* kbd-interactive */ 329 int info_req_seen; 330 int attempt_kbdint; 331 /* password */ 332 int attempt_passwd; 333 /* generic */ 334 void *methoddata; 335 }; 336 337 struct cauthmethod { 338 char *name; /* string to compare against server's list */ 339 int (*userauth)(struct ssh *ssh); 340 void (*cleanup)(struct ssh *ssh); 341 int *enabled; /* flag in option struct that enables method */ 342 int *batch_flag; /* flag in option struct that disables method */ 343 }; 344 345 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 346 static int input_userauth_success(int, u_int32_t, struct ssh *); 347 static int input_userauth_failure(int, u_int32_t, struct ssh *); 348 static int input_userauth_banner(int, u_int32_t, struct ssh *); 349 static int input_userauth_error(int, u_int32_t, struct ssh *); 350 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 351 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 352 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 353 354 static int userauth_none(struct ssh *); 355 static int userauth_pubkey(struct ssh *); 356 static int userauth_passwd(struct ssh *); 357 static int userauth_kbdint(struct ssh *); 358 static int userauth_hostbased(struct ssh *); 359 360 #ifdef GSSAPI 361 static int userauth_gssapi(struct ssh *); 362 static void userauth_gssapi_cleanup(struct ssh *); 363 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 364 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 365 static int input_gssapi_error(int, u_int32_t, struct ssh *); 366 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 367 #endif 368 369 void userauth(struct ssh *, char *); 370 371 static void pubkey_cleanup(struct ssh *); 372 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 373 static void pubkey_prepare(struct ssh *, Authctxt *); 374 static void pubkey_reset(Authctxt *); 375 static struct sshkey *load_identity_file(Identity *); 376 377 static Authmethod *authmethod_get(char *authlist); 378 static Authmethod *authmethod_lookup(const char *name); 379 static char *authmethods_get(void); 380 381 Authmethod authmethods[] = { 382 #ifdef GSSAPI 383 {"gssapi-with-mic", 384 userauth_gssapi, 385 userauth_gssapi_cleanup, 386 &options.gss_authentication, 387 NULL}, 388 #endif 389 {"hostbased", 390 userauth_hostbased, 391 NULL, 392 &options.hostbased_authentication, 393 NULL}, 394 {"publickey", 395 userauth_pubkey, 396 NULL, 397 &options.pubkey_authentication, 398 NULL}, 399 {"keyboard-interactive", 400 userauth_kbdint, 401 NULL, 402 &options.kbd_interactive_authentication, 403 &options.batch_mode}, 404 {"password", 405 userauth_passwd, 406 NULL, 407 &options.password_authentication, 408 &options.batch_mode}, 409 {"none", 410 userauth_none, 411 NULL, 412 NULL, 413 NULL}, 414 {NULL, NULL, NULL, NULL, NULL} 415 }; 416 417 void 418 ssh_userauth2(struct ssh *ssh, const char *local_user, 419 const char *server_user, char *host, Sensitive *sensitive) 420 { 421 Authctxt authctxt; 422 int r; 423 424 if (options.preferred_authentications == NULL) 425 options.preferred_authentications = authmethods_get(); 426 427 /* setup authentication context */ 428 memset(&authctxt, 0, sizeof(authctxt)); 429 authctxt.server_user = server_user; 430 authctxt.local_user = local_user; 431 authctxt.host = host; 432 authctxt.service = "ssh-connection"; /* service name */ 433 authctxt.success = 0; 434 authctxt.method = authmethod_lookup("none"); 435 authctxt.authlist = NULL; 436 authctxt.methoddata = NULL; 437 authctxt.sensitive = sensitive; 438 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 439 authctxt.info_req_seen = 0; 440 authctxt.attempt_kbdint = 0; 441 authctxt.attempt_passwd = 0; 442 #if GSSAPI 443 authctxt.gss_supported_mechs = NULL; 444 authctxt.mech_tried = 0; 445 #endif 446 authctxt.agent_fd = -1; 447 if (authctxt.method == NULL) 448 fatal_f("internal error: cannot send userauth none request"); 449 450 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 451 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 452 (r = sshpkt_send(ssh)) != 0) 453 fatal_fr(r, "send packet"); 454 455 ssh->authctxt = &authctxt; 456 ssh_dispatch_init(ssh, &input_userauth_error); 457 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 458 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 459 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 460 pubkey_cleanup(ssh); 461 #ifdef GSSAPI 462 if (authctxt.gss_supported_mechs != NULL) { 463 u_int ms; 464 465 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 466 authctxt.gss_supported_mechs = NULL; 467 } 468 #endif 469 ssh->authctxt = NULL; 470 471 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 472 473 if (!authctxt.success) 474 fatal("Authentication failed."); 475 if (ssh_packet_connection_is_on_socket(ssh)) { 476 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 477 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 478 authctxt.method->name); 479 } else { 480 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 481 authctxt.method->name); 482 } 483 } 484 485 static int 486 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 487 { 488 int r; 489 490 if (ssh_packet_remaining(ssh) > 0) { 491 char *reply; 492 493 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 494 goto out; 495 debug2("service_accept: %s", reply); 496 free(reply); 497 } else { 498 debug2("buggy server: service_accept w/o service"); 499 } 500 if ((r = sshpkt_get_end(ssh)) != 0) 501 goto out; 502 debug("SSH2_MSG_SERVICE_ACCEPT received"); 503 504 /* initial userauth request */ 505 userauth_none(ssh); 506 507 /* accept EXT_INFO at any time during userauth */ 508 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 509 &kex_input_ext_info : &input_userauth_error); 510 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 511 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 512 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 513 r = 0; 514 out: 515 return r; 516 } 517 518 void 519 userauth(struct ssh *ssh, char *authlist) 520 { 521 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 522 523 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 524 authctxt->method->cleanup(ssh); 525 526 free(authctxt->methoddata); 527 authctxt->methoddata = NULL; 528 if (authlist == NULL) { 529 authlist = authctxt->authlist; 530 } else { 531 free(authctxt->authlist); 532 authctxt->authlist = authlist; 533 } 534 for (;;) { 535 Authmethod *method = authmethod_get(authlist); 536 if (method == NULL) 537 fatal("%s@%s: Permission denied (%s).", 538 authctxt->server_user, authctxt->host, authlist); 539 authctxt->method = method; 540 541 /* reset the per method handler */ 542 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 543 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 544 545 /* and try new method */ 546 if (method->userauth(ssh) != 0) { 547 debug2("we sent a %s packet, wait for reply", method->name); 548 break; 549 } else { 550 debug2("we did not send a packet, disable method"); 551 method->enabled = NULL; 552 } 553 } 554 } 555 556 static int 557 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 558 { 559 fatal_f("bad message during authentication: type %d", type); 560 return 0; 561 } 562 563 static int 564 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 565 { 566 char *msg = NULL; 567 size_t len; 568 int r; 569 570 debug3_f("entering"); 571 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 572 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 573 goto out; 574 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 575 fmprintf(stderr, "%s", msg); 576 r = 0; 577 out: 578 free(msg); 579 return r; 580 } 581 582 static int 583 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 584 { 585 Authctxt *authctxt = ssh->authctxt; 586 587 if (authctxt == NULL) 588 fatal_f("no authentication context"); 589 free(authctxt->authlist); 590 authctxt->authlist = NULL; 591 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 592 authctxt->method->cleanup(ssh); 593 free(authctxt->methoddata); 594 authctxt->methoddata = NULL; 595 authctxt->success = 1; /* break out */ 596 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 597 return 0; 598 } 599 600 #if 0 601 static int 602 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 603 { 604 Authctxt *authctxt = ssh->authctxt; 605 606 if (authctxt == NULL) 607 fatal_f("no authentication context"); 608 609 fatal("Unexpected authentication success during %s.", 610 authctxt->method->name); 611 return 0; 612 } 613 #endif 614 615 static int 616 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 617 { 618 Authctxt *authctxt = ssh->authctxt; 619 char *authlist = NULL; 620 u_char partial; 621 622 if (authctxt == NULL) 623 fatal("input_userauth_failure: no authentication context"); 624 625 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 626 sshpkt_get_u8(ssh, &partial) != 0 || 627 sshpkt_get_end(ssh) != 0) 628 goto out; 629 630 if (partial != 0) { 631 verbose("Authenticated using \"%s\" with partial success.", 632 authctxt->method->name); 633 /* reset state */ 634 pubkey_reset(authctxt); 635 } 636 debug("Authentications that can continue: %s", authlist); 637 638 userauth(ssh, authlist); 639 authlist = NULL; 640 out: 641 free(authlist); 642 return 0; 643 } 644 645 /* 646 * Format an identity for logging including filename, key type, fingerprint 647 * and location (agent, etc.). Caller must free. 648 */ 649 static char * 650 format_identity(Identity *id) 651 { 652 char *fp = NULL, *ret = NULL; 653 const char *note = ""; 654 655 if (id->key != NULL) { 656 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 657 SSH_FP_DEFAULT); 658 } 659 if (id->key) { 660 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 661 note = " token"; 662 else if (sshkey_is_sk(id->key)) 663 note = " authenticator"; 664 } 665 xasprintf(&ret, "%s %s%s%s%s%s%s", 666 id->filename, 667 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 668 fp ? fp : "", 669 id->userprovided ? " explicit" : "", note, 670 id->agent_fd != -1 ? " agent" : ""); 671 free(fp); 672 return ret; 673 } 674 675 static int 676 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 677 { 678 Authctxt *authctxt = ssh->authctxt; 679 struct sshkey *key = NULL; 680 Identity *id = NULL; 681 int pktype, found = 0, sent = 0; 682 size_t blen; 683 char *pkalg = NULL, *fp = NULL, *ident = NULL; 684 u_char *pkblob = NULL; 685 int r; 686 687 if (authctxt == NULL) 688 fatal("input_userauth_pk_ok: no authentication context"); 689 690 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 691 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 692 (r = sshpkt_get_end(ssh)) != 0) 693 goto done; 694 695 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 696 debug_f("server sent unknown pkalg %s", pkalg); 697 goto done; 698 } 699 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 700 debug_r(r, "no key from blob. pkalg %s", pkalg); 701 goto done; 702 } 703 if (key->type != pktype) { 704 error("input_userauth_pk_ok: type mismatch " 705 "for decoded key (received %d, expected %d)", 706 key->type, pktype); 707 goto done; 708 } 709 710 /* 711 * search keys in the reverse order, because last candidate has been 712 * moved to the end of the queue. this also avoids confusion by 713 * duplicate keys 714 */ 715 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 716 if (sshkey_equal(key, id->key)) { 717 found = 1; 718 break; 719 } 720 } 721 if (!found || id == NULL) { 722 fp = sshkey_fingerprint(key, options.fingerprint_hash, 723 SSH_FP_DEFAULT); 724 error_f("server replied with unknown key: %s %s", 725 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 726 goto done; 727 } 728 ident = format_identity(id); 729 debug("Server accepts key: %s", ident); 730 sent = sign_and_send_pubkey(ssh, id); 731 r = 0; 732 done: 733 sshkey_free(key); 734 free(ident); 735 free(fp); 736 free(pkalg); 737 free(pkblob); 738 739 /* try another method if we did not send a packet */ 740 if (r == 0 && sent == 0) 741 userauth(ssh, NULL); 742 return r; 743 } 744 745 #ifdef GSSAPI 746 static int 747 userauth_gssapi(struct ssh *ssh) 748 { 749 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 750 Gssctxt *gssctxt = NULL; 751 OM_uint32 min; 752 int r, ok = 0; 753 gss_OID mech = NULL; 754 755 /* Try one GSSAPI method at a time, rather than sending them all at 756 * once. */ 757 758 if (authctxt->gss_supported_mechs == NULL) 759 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 760 761 /* Check to see whether the mechanism is usable before we offer it */ 762 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 763 !ok) { 764 mech = &authctxt->gss_supported_mechs-> 765 elements[authctxt->mech_tried]; 766 /* My DER encoding requires length<128 */ 767 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 768 mech, authctxt->host)) { 769 ok = 1; /* Mechanism works */ 770 } else { 771 authctxt->mech_tried++; 772 } 773 } 774 775 if (!ok || mech == NULL) 776 return 0; 777 778 authctxt->methoddata=(void *)gssctxt; 779 780 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 781 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 782 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 783 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 784 (r = sshpkt_put_u32(ssh, 1)) != 0 || 785 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 786 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 787 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 788 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 789 (r = sshpkt_send(ssh)) != 0) 790 fatal_fr(r, "send packet"); 791 792 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 793 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 794 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 795 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 796 797 authctxt->mech_tried++; /* Move along to next candidate */ 798 799 return 1; 800 } 801 802 static void 803 userauth_gssapi_cleanup(struct ssh *ssh) 804 { 805 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 806 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 807 808 ssh_gssapi_delete_ctx(&gssctxt); 809 authctxt->methoddata = NULL; 810 } 811 812 static OM_uint32 813 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 814 { 815 Authctxt *authctxt = ssh->authctxt; 816 Gssctxt *gssctxt = authctxt->methoddata; 817 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 818 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 819 gss_buffer_desc gssbuf; 820 OM_uint32 status, ms, flags; 821 int r; 822 823 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 824 recv_tok, &send_tok, &flags); 825 826 if (send_tok.length > 0) { 827 u_char type = GSS_ERROR(status) ? 828 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 829 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 830 831 if ((r = sshpkt_start(ssh, type)) != 0 || 832 (r = sshpkt_put_string(ssh, send_tok.value, 833 send_tok.length)) != 0 || 834 (r = sshpkt_send(ssh)) != 0) 835 fatal_fr(r, "send %u packet", type); 836 837 gss_release_buffer(&ms, &send_tok); 838 } 839 840 if (status == GSS_S_COMPLETE) { 841 /* send either complete or MIC, depending on mechanism */ 842 if (!(flags & GSS_C_INTEG_FLAG)) { 843 if ((r = sshpkt_start(ssh, 844 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 845 (r = sshpkt_send(ssh)) != 0) 846 fatal_fr(r, "send completion"); 847 } else { 848 struct sshbuf *b; 849 850 if ((b = sshbuf_new()) == NULL) 851 fatal_f("sshbuf_new failed"); 852 ssh_gssapi_buildmic(b, authctxt->server_user, 853 authctxt->service, "gssapi-with-mic", 854 ssh->kex->session_id); 855 856 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 857 fatal_f("sshbuf_mutable_ptr failed"); 858 gssbuf.length = sshbuf_len(b); 859 860 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 861 862 if (!GSS_ERROR(status)) { 863 if ((r = sshpkt_start(ssh, 864 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 865 (r = sshpkt_put_string(ssh, mic.value, 866 mic.length)) != 0 || 867 (r = sshpkt_send(ssh)) != 0) 868 fatal_fr(r, "send MIC"); 869 } 870 871 sshbuf_free(b); 872 gss_release_buffer(&ms, &mic); 873 } 874 } 875 876 return status; 877 } 878 879 static int 880 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 881 { 882 Authctxt *authctxt = ssh->authctxt; 883 Gssctxt *gssctxt; 884 size_t oidlen; 885 u_char *oidv = NULL; 886 int r; 887 888 if (authctxt == NULL) 889 fatal("input_gssapi_response: no authentication context"); 890 gssctxt = authctxt->methoddata; 891 892 /* Setup our OID */ 893 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 894 goto done; 895 896 if (oidlen <= 2 || 897 oidv[0] != SSH_GSS_OIDTYPE || 898 oidv[1] != oidlen - 2) { 899 debug("Badly encoded mechanism OID received"); 900 userauth(ssh, NULL); 901 goto ok; 902 } 903 904 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 905 fatal("Server returned different OID than expected"); 906 907 if ((r = sshpkt_get_end(ssh)) != 0) 908 goto done; 909 910 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 911 /* Start again with next method on list */ 912 debug("Trying to start again"); 913 userauth(ssh, NULL); 914 goto ok; 915 } 916 ok: 917 r = 0; 918 done: 919 free(oidv); 920 return r; 921 } 922 923 static int 924 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 925 { 926 Authctxt *authctxt = ssh->authctxt; 927 gss_buffer_desc recv_tok; 928 u_char *p = NULL; 929 size_t len; 930 OM_uint32 status; 931 int r; 932 933 if (authctxt == NULL) 934 fatal("input_gssapi_response: no authentication context"); 935 936 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 937 (r = sshpkt_get_end(ssh)) != 0) 938 goto out; 939 940 recv_tok.value = p; 941 recv_tok.length = len; 942 status = process_gssapi_token(ssh, &recv_tok); 943 944 /* Start again with the next method in the list */ 945 if (GSS_ERROR(status)) { 946 userauth(ssh, NULL); 947 /* ok */ 948 } 949 r = 0; 950 out: 951 free(p); 952 return r; 953 } 954 955 static int 956 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 957 { 958 Authctxt *authctxt = ssh->authctxt; 959 Gssctxt *gssctxt; 960 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 961 gss_buffer_desc recv_tok; 962 OM_uint32 ms; 963 u_char *p = NULL; 964 size_t len; 965 int r; 966 967 if (authctxt == NULL) 968 fatal("input_gssapi_response: no authentication context"); 969 gssctxt = authctxt->methoddata; 970 971 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 972 (r = sshpkt_get_end(ssh)) != 0) { 973 free(p); 974 return r; 975 } 976 977 /* Stick it into GSSAPI and see what it says */ 978 recv_tok.value = p; 979 recv_tok.length = len; 980 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 981 &recv_tok, &send_tok, NULL); 982 free(p); 983 gss_release_buffer(&ms, &send_tok); 984 985 /* Server will be returning a failed packet after this one */ 986 return 0; 987 } 988 989 static int 990 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 991 { 992 char *msg = NULL; 993 char *lang = NULL; 994 int r; 995 996 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 997 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 998 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 999 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1000 goto out; 1001 r = sshpkt_get_end(ssh); 1002 debug("Server GSSAPI Error:\n%s", msg); 1003 out: 1004 free(msg); 1005 free(lang); 1006 return r; 1007 } 1008 #endif /* GSSAPI */ 1009 1010 static int 1011 userauth_none(struct ssh *ssh) 1012 { 1013 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1014 int r; 1015 1016 /* initial userauth request */ 1017 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1018 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1019 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1020 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1021 (r = sshpkt_send(ssh)) != 0) 1022 fatal_fr(r, "send packet"); 1023 return 1; 1024 } 1025 1026 static int 1027 userauth_passwd(struct ssh *ssh) 1028 { 1029 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1030 char *password, *prompt = NULL; 1031 const char *host = options.host_key_alias ? options.host_key_alias : 1032 authctxt->host; 1033 int r; 1034 1035 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1036 return 0; 1037 1038 if (authctxt->attempt_passwd != 1) 1039 error("Permission denied, please try again."); 1040 1041 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1042 password = read_passphrase(prompt, 0); 1043 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1044 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1045 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1046 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1047 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1048 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1049 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1050 (r = sshpkt_send(ssh)) != 0) 1051 fatal_fr(r, "send packet"); 1052 1053 free(prompt); 1054 if (password != NULL) 1055 freezero(password, strlen(password)); 1056 1057 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1058 &input_userauth_passwd_changereq); 1059 1060 return 1; 1061 } 1062 1063 /* 1064 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1065 */ 1066 static int 1067 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1068 { 1069 Authctxt *authctxt = ssh->authctxt; 1070 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1071 char prompt[256]; 1072 const char *host; 1073 int r; 1074 1075 debug2("input_userauth_passwd_changereq"); 1076 1077 if (authctxt == NULL) 1078 fatal("input_userauth_passwd_changereq: " 1079 "no authentication context"); 1080 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1081 1082 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1083 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1084 goto out; 1085 if (strlen(info) > 0) 1086 logit("%s", info); 1087 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1088 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1089 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1090 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1091 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1092 goto out; 1093 1094 snprintf(prompt, sizeof(prompt), 1095 "Enter %.30s@%.128s's old password: ", 1096 authctxt->server_user, host); 1097 password = read_passphrase(prompt, 0); 1098 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1099 goto out; 1100 1101 freezero(password, strlen(password)); 1102 password = NULL; 1103 while (password == NULL) { 1104 snprintf(prompt, sizeof(prompt), 1105 "Enter %.30s@%.128s's new password: ", 1106 authctxt->server_user, host); 1107 password = read_passphrase(prompt, RP_ALLOW_EOF); 1108 if (password == NULL) { 1109 /* bail out */ 1110 r = 0; 1111 goto out; 1112 } 1113 snprintf(prompt, sizeof(prompt), 1114 "Retype %.30s@%.128s's new password: ", 1115 authctxt->server_user, host); 1116 retype = read_passphrase(prompt, 0); 1117 if (strcmp(password, retype) != 0) { 1118 freezero(password, strlen(password)); 1119 logit("Mismatch; try again, EOF to quit."); 1120 password = NULL; 1121 } 1122 freezero(retype, strlen(retype)); 1123 } 1124 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1125 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1126 (r = sshpkt_send(ssh)) != 0) 1127 goto out; 1128 1129 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1130 &input_userauth_passwd_changereq); 1131 r = 0; 1132 out: 1133 if (password) 1134 freezero(password, strlen(password)); 1135 free(info); 1136 free(lang); 1137 return r; 1138 } 1139 1140 /* 1141 * Select an algorithm for publickey signatures. 1142 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1143 * 1144 * Call with ssh==NULL to ignore server-sig-algs extension list and 1145 * only attempt with the key's base signature type. 1146 */ 1147 static char * 1148 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1149 { 1150 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1151 const char *server_sig_algs; 1152 1153 /* 1154 * The signature algorithm will only differ from the key algorithm 1155 * for RSA keys/certs and when the server advertises support for 1156 * newer (SHA2) algorithms. 1157 */ 1158 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1159 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1160 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1161 /* Filter base key signature alg against our configuration */ 1162 return match_list(sshkey_ssh_name(key), 1163 options.pubkey_accepted_algos, NULL); 1164 } 1165 1166 /* 1167 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1168 * fails to advertise it via SSH2_MSG_EXT_INFO. 1169 */ 1170 server_sig_algs = ssh->kex->server_sig_algs; 1171 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1172 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1173 1174 /* 1175 * For RSA keys/certs, since these might have a different sig type: 1176 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1177 * that also appears in the supported signature algorithms list from 1178 * the server. 1179 */ 1180 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1181 while ((cp = strsep(&allowed, ",")) != NULL) { 1182 if (sshkey_type_from_name(cp) != key->type) 1183 continue; 1184 tmp = match_list(sshkey_sigalg_by_name(cp), 1185 server_sig_algs, NULL); 1186 if (tmp != NULL) 1187 alg = xstrdup(cp); 1188 free(tmp); 1189 if (alg != NULL) 1190 break; 1191 } 1192 free(oallowed); 1193 return alg; 1194 } 1195 1196 static int 1197 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1198 const u_char *data, size_t datalen, u_int compat, const char *alg) 1199 { 1200 struct sshkey *sign_key = NULL, *prv = NULL; 1201 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1202 struct notifier_ctx *notifier = NULL; 1203 char *fp = NULL, *pin = NULL, *prompt = NULL; 1204 1205 *sigp = NULL; 1206 *lenp = 0; 1207 1208 /* The agent supports this key. */ 1209 if (id->key != NULL && id->agent_fd != -1) { 1210 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1211 data, datalen, alg, compat); 1212 } 1213 1214 /* 1215 * We have already loaded the private key or the private key is 1216 * stored in external hardware. 1217 */ 1218 if (id->key != NULL && 1219 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1220 sign_key = id->key; 1221 is_agent = 1; 1222 } else { 1223 /* Load the private key from the file. */ 1224 if ((prv = load_identity_file(id)) == NULL) 1225 return SSH_ERR_KEY_NOT_FOUND; 1226 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1227 error_f("private key %s contents do not match public", 1228 id->filename); 1229 r = SSH_ERR_KEY_NOT_FOUND; 1230 goto out; 1231 } 1232 sign_key = prv; 1233 } 1234 retry_pin: 1235 /* Prompt for touch for non-agent FIDO keys that request UP */ 1236 if (!is_agent && sshkey_is_sk(sign_key) && 1237 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1238 /* XXX should batch mode just skip these? */ 1239 if ((fp = sshkey_fingerprint(sign_key, 1240 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1241 fatal_f("fingerprint failed"); 1242 notifier = notify_start(options.batch_mode, 1243 "Confirm user presence for key %s %s", 1244 sshkey_type(sign_key), fp); 1245 free(fp); 1246 } 1247 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1248 alg, options.sk_provider, pin, compat)) != 0) { 1249 debug_fr(r, "sshkey_sign"); 1250 if (!retried && pin == NULL && !is_agent && 1251 sshkey_is_sk(sign_key) && 1252 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1253 notify_complete(notifier, NULL); 1254 notifier = NULL; 1255 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1256 sshkey_type(sign_key), id->filename); 1257 pin = read_passphrase(prompt, 0); 1258 retried = 1; 1259 goto retry_pin; 1260 } 1261 goto out; 1262 } 1263 1264 /* 1265 * PKCS#11 tokens may not support all signature algorithms, 1266 * so check what we get back. 1267 */ 1268 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1269 debug_fr(r, "sshkey_check_sigtype"); 1270 goto out; 1271 } 1272 /* success */ 1273 r = 0; 1274 out: 1275 free(prompt); 1276 if (pin != NULL) 1277 freezero(pin, strlen(pin)); 1278 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1279 sshkey_free(prv); 1280 return r; 1281 } 1282 1283 static int 1284 id_filename_matches(Identity *id, Identity *private_id) 1285 { 1286 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1287 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1288 size_t i, slen; 1289 1290 if (strcmp(id->filename, private_id->filename) == 0) 1291 return 1; 1292 for (i = 0; suffixes[i]; i++) { 1293 slen = strlen(suffixes[i]); 1294 if (len > slen && plen == len - slen && 1295 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1296 memcmp(id->filename, private_id->filename, plen) == 0) 1297 return 1; 1298 } 1299 return 0; 1300 } 1301 1302 static int 1303 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1304 { 1305 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1306 struct sshbuf *b = NULL; 1307 Identity *private_id, *sign_id = NULL; 1308 u_char *signature = NULL; 1309 size_t slen = 0, skip = 0; 1310 int r, fallback_sigtype, sent = 0; 1311 char *alg = NULL, *fp = NULL; 1312 const char *loc = "", *method = "publickey"; 1313 int hostbound = 0; 1314 1315 /* prefer host-bound pubkey signatures if supported by server */ 1316 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1317 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1318 hostbound = 1; 1319 method = "publickey-hostbound-v00@openssh.com"; 1320 } 1321 1322 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1323 SSH_FP_DEFAULT)) == NULL) 1324 return 0; 1325 1326 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1327 1328 /* 1329 * If the key is an certificate, try to find a matching private key 1330 * and use it to complete the signature. 1331 * If no such private key exists, fall back to trying the certificate 1332 * key itself in case it has a private half already loaded. 1333 * This will try to set sign_id to the private key that will perform 1334 * the signature. 1335 */ 1336 if (sshkey_is_cert(id->key)) { 1337 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1338 if (sshkey_equal_public(id->key, private_id->key) && 1339 id->key->type != private_id->key->type) { 1340 sign_id = private_id; 1341 break; 1342 } 1343 } 1344 /* 1345 * Exact key matches are preferred, but also allow 1346 * filename matches for non-PKCS#11/agent keys that 1347 * didn't load public keys. This supports the case 1348 * of keeping just a private key file and public 1349 * certificate on disk. 1350 */ 1351 if (sign_id == NULL && 1352 !id->isprivate && id->agent_fd == -1 && 1353 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1354 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1355 if (private_id->key == NULL && 1356 id_filename_matches(id, private_id)) { 1357 sign_id = private_id; 1358 break; 1359 } 1360 } 1361 } 1362 if (sign_id != NULL) { 1363 debug2_f("using private key \"%s\"%s for " 1364 "certificate", sign_id->filename, 1365 sign_id->agent_fd != -1 ? " from agent" : ""); 1366 } else { 1367 debug_f("no separate private key for certificate " 1368 "\"%s\"", id->filename); 1369 } 1370 } 1371 1372 /* 1373 * If the above didn't select another identity to do the signing 1374 * then default to the one we started with. 1375 */ 1376 if (sign_id == NULL) 1377 sign_id = id; 1378 1379 /* assemble and sign data */ 1380 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1381 free(alg); 1382 slen = 0; 1383 signature = NULL; 1384 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1385 id->key)) == NULL) { 1386 error_f("no mutual signature supported"); 1387 goto out; 1388 } 1389 debug3_f("signing using %s %s", alg, fp); 1390 1391 sshbuf_free(b); 1392 if ((b = sshbuf_new()) == NULL) 1393 fatal_f("sshbuf_new failed"); 1394 if (ssh->compat & SSH_OLD_SESSIONID) { 1395 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1396 fatal_fr(r, "sshbuf_putb"); 1397 } else { 1398 if ((r = sshbuf_put_stringb(b, 1399 ssh->kex->session_id)) != 0) 1400 fatal_fr(r, "sshbuf_put_stringb"); 1401 } 1402 skip = sshbuf_len(b); 1403 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1404 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1405 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1406 (r = sshbuf_put_cstring(b, method)) != 0 || 1407 (r = sshbuf_put_u8(b, 1)) != 0 || 1408 (r = sshbuf_put_cstring(b, alg)) != 0 || 1409 (r = sshkey_puts(id->key, b)) != 0) { 1410 fatal_fr(r, "assemble signed data"); 1411 } 1412 if (hostbound) { 1413 if (ssh->kex->initial_hostkey == NULL) { 1414 fatal_f("internal error: initial hostkey " 1415 "not recorded"); 1416 } 1417 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1418 fatal_fr(r, "assemble %s hostkey", method); 1419 } 1420 /* generate signature */ 1421 r = identity_sign(sign_id, &signature, &slen, 1422 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1423 if (r == 0) 1424 break; 1425 else if (r == SSH_ERR_KEY_NOT_FOUND) 1426 goto out; /* soft failure */ 1427 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1428 !fallback_sigtype) { 1429 if (sign_id->agent_fd != -1) 1430 loc = "agent "; 1431 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1432 loc = "token "; 1433 logit("%skey %s %s returned incorrect signature type", 1434 loc, sshkey_type(id->key), fp); 1435 continue; 1436 } 1437 error_fr(r, "signing failed for %s \"%s\"%s", 1438 sshkey_type(sign_id->key), sign_id->filename, 1439 id->agent_fd != -1 ? " from agent" : ""); 1440 goto out; 1441 } 1442 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1443 fatal_f("no signature"); 1444 1445 /* append signature */ 1446 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1447 fatal_fr(r, "append signature"); 1448 1449 #ifdef DEBUG_PK 1450 sshbuf_dump(b, stderr); 1451 #endif 1452 /* skip session id and packet type */ 1453 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1454 fatal_fr(r, "consume"); 1455 1456 /* put remaining data from buffer into packet */ 1457 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1458 (r = sshpkt_putb(ssh, b)) != 0 || 1459 (r = sshpkt_send(ssh)) != 0) 1460 fatal_fr(r, "enqueue request"); 1461 1462 /* success */ 1463 sent = 1; 1464 1465 out: 1466 free(fp); 1467 free(alg); 1468 sshbuf_free(b); 1469 freezero(signature, slen); 1470 return sent; 1471 } 1472 1473 static int 1474 send_pubkey_test(struct ssh *ssh, Identity *id) 1475 { 1476 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1477 u_char *blob = NULL; 1478 char *alg = NULL; 1479 size_t bloblen; 1480 u_int have_sig = 0; 1481 int sent = 0, r; 1482 1483 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1484 debug_f("no mutual signature algorithm"); 1485 goto out; 1486 } 1487 1488 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1489 /* we cannot handle this key */ 1490 debug3_f("cannot handle key"); 1491 goto out; 1492 } 1493 /* register callback for USERAUTH_PK_OK message */ 1494 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1495 1496 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1497 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1498 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1499 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1500 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1501 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1502 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1503 (r = sshpkt_send(ssh)) != 0) 1504 fatal_fr(r, "send packet"); 1505 sent = 1; 1506 1507 out: 1508 free(alg); 1509 free(blob); 1510 return sent; 1511 } 1512 1513 static struct sshkey * 1514 load_identity_file(Identity *id) 1515 { 1516 struct sshkey *private = NULL; 1517 char prompt[300], *passphrase, *comment; 1518 int r, quit = 0, i; 1519 struct stat st; 1520 1521 if (stat(id->filename, &st) == -1) { 1522 do_log2(id->userprovided ? 1523 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1524 "no such identity: %s: %s", id->filename, strerror(errno)); 1525 return NULL; 1526 } 1527 snprintf(prompt, sizeof prompt, 1528 "Enter passphrase for key '%.100s': ", id->filename); 1529 for (i = 0; i <= options.number_of_password_prompts; i++) { 1530 if (i == 0) 1531 passphrase = ""; 1532 else { 1533 passphrase = read_passphrase(prompt, 0); 1534 if (*passphrase == '\0') { 1535 debug2("no passphrase given, try next key"); 1536 free(passphrase); 1537 break; 1538 } 1539 } 1540 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1541 passphrase, &private, &comment))) { 1542 case 0: 1543 break; 1544 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1545 if (options.batch_mode) { 1546 quit = 1; 1547 break; 1548 } 1549 if (i != 0) 1550 debug2("bad passphrase given, try again..."); 1551 break; 1552 case SSH_ERR_SYSTEM_ERROR: 1553 if (errno == ENOENT) { 1554 debug2_r(r, "Load key \"%s\"", id->filename); 1555 quit = 1; 1556 break; 1557 } 1558 /* FALLTHROUGH */ 1559 default: 1560 error_r(r, "Load key \"%s\"", id->filename); 1561 quit = 1; 1562 break; 1563 } 1564 if (private != NULL && sshkey_is_sk(private) && 1565 options.sk_provider == NULL) { 1566 debug("key \"%s\" is an authenticator-hosted key, " 1567 "but no provider specified", id->filename); 1568 sshkey_free(private); 1569 private = NULL; 1570 quit = 1; 1571 } 1572 if (!quit && (r = sshkey_check_rsa_length(private, 1573 options.required_rsa_size)) != 0) { 1574 debug_fr(r, "Skipping key %s", id->filename); 1575 sshkey_free(private); 1576 private = NULL; 1577 quit = 1; 1578 } 1579 if (!quit && private != NULL && id->agent_fd == -1 && 1580 !(id->key && id->isprivate)) 1581 maybe_add_key_to_agent(id->filename, private, comment, 1582 passphrase); 1583 if (i > 0) 1584 freezero(passphrase, strlen(passphrase)); 1585 free(comment); 1586 if (private != NULL || quit) 1587 break; 1588 } 1589 return private; 1590 } 1591 1592 static int 1593 key_type_allowed_by_config(struct sshkey *key) 1594 { 1595 if (match_pattern_list(sshkey_ssh_name(key), 1596 options.pubkey_accepted_algos, 0) == 1) 1597 return 1; 1598 1599 /* RSA keys/certs might be allowed by alternate signature types */ 1600 switch (key->type) { 1601 case KEY_RSA: 1602 if (match_pattern_list("rsa-sha2-512", 1603 options.pubkey_accepted_algos, 0) == 1) 1604 return 1; 1605 if (match_pattern_list("rsa-sha2-256", 1606 options.pubkey_accepted_algos, 0) == 1) 1607 return 1; 1608 break; 1609 case KEY_RSA_CERT: 1610 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1611 options.pubkey_accepted_algos, 0) == 1) 1612 return 1; 1613 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1614 options.pubkey_accepted_algos, 0) == 1) 1615 return 1; 1616 break; 1617 } 1618 return 0; 1619 } 1620 1621 /* obtain a list of keys from the agent */ 1622 static int 1623 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1624 struct ssh_identitylist **idlistp) 1625 { 1626 int r, agent_fd; 1627 struct ssh_identitylist *idlist; 1628 1629 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1630 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1631 debug_fr(r, "ssh_get_authentication_socket"); 1632 return r; 1633 } 1634 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1635 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1636 debug_f("bound agent to hostkey"); 1637 else 1638 debug2_fr(r, "ssh_agent_bind_hostkey"); 1639 1640 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1641 debug_fr(r, "ssh_fetch_identitylist"); 1642 close(agent_fd); 1643 return r; 1644 } 1645 /* success */ 1646 *agent_fdp = agent_fd; 1647 *idlistp = idlist; 1648 debug_f("agent returned %zu keys", idlist->nkeys); 1649 return 0; 1650 } 1651 1652 /* 1653 * try keys in the following order: 1654 * 1. certificates listed in the config file 1655 * 2. other input certificates 1656 * 3. agent keys that are found in the config file 1657 * 4. other agent keys 1658 * 5. keys that are only listed in the config file 1659 */ 1660 static void 1661 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1662 { 1663 struct identity *id, *id2, *tmp; 1664 struct idlist agent, files, *preferred; 1665 struct sshkey *key; 1666 int disallowed, agent_fd = -1, i, r, found; 1667 size_t j; 1668 struct ssh_identitylist *idlist; 1669 char *cp, *ident; 1670 1671 TAILQ_INIT(&agent); /* keys from the agent */ 1672 TAILQ_INIT(&files); /* keys from the config file */ 1673 preferred = &authctxt->keys; 1674 TAILQ_INIT(preferred); /* preferred order of keys */ 1675 1676 /* list of keys stored in the filesystem and PKCS#11 */ 1677 for (i = 0; i < options.num_identity_files; i++) { 1678 key = options.identity_keys[i]; 1679 if (key && key->cert && 1680 key->cert->type != SSH2_CERT_TYPE_USER) { 1681 debug_f("ignoring certificate %s: not a user " 1682 "certificate", options.identity_files[i]); 1683 continue; 1684 } 1685 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1686 debug_f("ignoring authenticator-hosted key %s as no " 1687 "SecurityKeyProvider has been specified", 1688 options.identity_files[i]); 1689 continue; 1690 } 1691 options.identity_keys[i] = NULL; 1692 id = xcalloc(1, sizeof(*id)); 1693 id->agent_fd = -1; 1694 id->key = key; 1695 id->filename = xstrdup(options.identity_files[i]); 1696 id->userprovided = options.identity_file_userprovided[i]; 1697 TAILQ_INSERT_TAIL(&files, id, next); 1698 } 1699 /* list of certificates specified by user */ 1700 for (i = 0; i < options.num_certificate_files; i++) { 1701 key = options.certificates[i]; 1702 if (!sshkey_is_cert(key) || key->cert == NULL || 1703 key->cert->type != SSH2_CERT_TYPE_USER) { 1704 debug_f("ignoring certificate %s: not a user " 1705 "certificate", options.identity_files[i]); 1706 continue; 1707 } 1708 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1709 debug_f("ignoring authenticator-hosted key " 1710 "certificate %s as no " 1711 "SecurityKeyProvider has been specified", 1712 options.identity_files[i]); 1713 continue; 1714 } 1715 id = xcalloc(1, sizeof(*id)); 1716 id->agent_fd = -1; 1717 id->key = key; 1718 id->filename = xstrdup(options.certificate_files[i]); 1719 id->userprovided = options.certificate_file_userprovided[i]; 1720 TAILQ_INSERT_TAIL(preferred, id, next); 1721 } 1722 /* list of keys supported by the agent */ 1723 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1724 for (j = 0; j < idlist->nkeys; j++) { 1725 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1726 options.required_rsa_size)) != 0) { 1727 debug_fr(r, "ignoring %s agent key", 1728 sshkey_ssh_name(idlist->keys[j])); 1729 continue; 1730 } 1731 found = 0; 1732 TAILQ_FOREACH(id, &files, next) { 1733 /* 1734 * agent keys from the config file are 1735 * preferred 1736 */ 1737 if (sshkey_equal(idlist->keys[j], id->key)) { 1738 TAILQ_REMOVE(&files, id, next); 1739 TAILQ_INSERT_TAIL(preferred, id, next); 1740 id->agent_fd = agent_fd; 1741 found = 1; 1742 break; 1743 } 1744 } 1745 if (!found && !options.identities_only) { 1746 id = xcalloc(1, sizeof(*id)); 1747 /* XXX "steals" key/comment from idlist */ 1748 id->key = idlist->keys[j]; 1749 id->filename = idlist->comments[j]; 1750 idlist->keys[j] = NULL; 1751 idlist->comments[j] = NULL; 1752 id->agent_fd = agent_fd; 1753 TAILQ_INSERT_TAIL(&agent, id, next); 1754 } 1755 } 1756 ssh_free_identitylist(idlist); 1757 /* append remaining agent keys */ 1758 TAILQ_CONCAT(preferred, &agent, next); 1759 authctxt->agent_fd = agent_fd; 1760 } 1761 /* Prefer PKCS11 keys that are explicitly listed */ 1762 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1763 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1764 continue; 1765 found = 0; 1766 TAILQ_FOREACH(id2, &files, next) { 1767 if (id2->key == NULL || 1768 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1769 continue; 1770 if (sshkey_equal(id->key, id2->key)) { 1771 TAILQ_REMOVE(&files, id, next); 1772 TAILQ_INSERT_TAIL(preferred, id, next); 1773 found = 1; 1774 break; 1775 } 1776 } 1777 /* If IdentitiesOnly set and key not found then don't use it */ 1778 if (!found && options.identities_only) { 1779 TAILQ_REMOVE(&files, id, next); 1780 freezero(id, sizeof(*id)); 1781 } 1782 } 1783 /* append remaining keys from the config file */ 1784 TAILQ_CONCAT(preferred, &files, next); 1785 /* finally, filter by PubkeyAcceptedAlgorithms */ 1786 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1787 disallowed = 0; 1788 cp = NULL; 1789 if (id->key == NULL) 1790 continue; 1791 if (!key_type_allowed_by_config(id->key)) { 1792 debug("Skipping %s key %s - corresponding algorithm " 1793 "not in PubkeyAcceptedAlgorithms", 1794 sshkey_ssh_name(id->key), id->filename); 1795 disallowed = 1; 1796 } else if (ssh->kex->server_sig_algs != NULL && 1797 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1798 debug("Skipping %s key %s - corresponding algorithm " 1799 "not supported by server", 1800 sshkey_ssh_name(id->key), id->filename); 1801 disallowed = 1; 1802 } 1803 free(cp); 1804 if (!disallowed) 1805 continue; 1806 /* remove key */ 1807 TAILQ_REMOVE(preferred, id, next); 1808 sshkey_free(id->key); 1809 free(id->filename); 1810 memset(id, 0, sizeof(*id)); 1811 } 1812 /* List the keys we plan on using */ 1813 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1814 ident = format_identity(id); 1815 debug("Will attempt key: %s", ident); 1816 free(ident); 1817 } 1818 debug2_f("done"); 1819 } 1820 1821 static void 1822 pubkey_cleanup(struct ssh *ssh) 1823 { 1824 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1825 Identity *id; 1826 1827 if (authctxt->agent_fd != -1) { 1828 ssh_close_authentication_socket(authctxt->agent_fd); 1829 authctxt->agent_fd = -1; 1830 } 1831 for (id = TAILQ_FIRST(&authctxt->keys); id; 1832 id = TAILQ_FIRST(&authctxt->keys)) { 1833 TAILQ_REMOVE(&authctxt->keys, id, next); 1834 sshkey_free(id->key); 1835 free(id->filename); 1836 free(id); 1837 } 1838 } 1839 1840 static void 1841 pubkey_reset(Authctxt *authctxt) 1842 { 1843 Identity *id; 1844 1845 TAILQ_FOREACH(id, &authctxt->keys, next) 1846 id->tried = 0; 1847 } 1848 1849 static int 1850 userauth_pubkey(struct ssh *ssh) 1851 { 1852 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1853 Identity *id; 1854 int sent = 0; 1855 char *ident; 1856 static int prepared; 1857 1858 if (!prepared) { 1859 pubkey_prepare(ssh, authctxt); 1860 prepared = 1; 1861 } 1862 1863 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1864 if (id->tried++) 1865 return (0); 1866 /* move key to the end of the queue */ 1867 TAILQ_REMOVE(&authctxt->keys, id, next); 1868 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1869 /* 1870 * send a test message if we have the public key. for 1871 * encrypted keys we cannot do this and have to load the 1872 * private key instead 1873 */ 1874 if (id->key != NULL) { 1875 ident = format_identity(id); 1876 debug("Offering public key: %s", ident); 1877 free(ident); 1878 sent = send_pubkey_test(ssh, id); 1879 } else { 1880 debug("Trying private key: %s", id->filename); 1881 id->key = load_identity_file(id); 1882 if (id->key != NULL) { 1883 if (id->key != NULL) { 1884 id->isprivate = 1; 1885 sent = sign_and_send_pubkey(ssh, id); 1886 } 1887 sshkey_free(id->key); 1888 id->key = NULL; 1889 id->isprivate = 0; 1890 } 1891 } 1892 if (sent) 1893 return (sent); 1894 } 1895 return (0); 1896 } 1897 1898 /* 1899 * Send userauth request message specifying keyboard-interactive method. 1900 */ 1901 static int 1902 userauth_kbdint(struct ssh *ssh) 1903 { 1904 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1905 int r; 1906 1907 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1908 return 0; 1909 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1910 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1911 debug3("userauth_kbdint: disable: no info_req_seen"); 1912 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1913 return 0; 1914 } 1915 1916 debug2("userauth_kbdint"); 1917 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1918 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1919 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1920 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1921 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1922 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1923 options.kbd_interactive_devices : "")) != 0 || 1924 (r = sshpkt_send(ssh)) != 0) 1925 fatal_fr(r, "send packet"); 1926 1927 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1928 return 1; 1929 } 1930 1931 /* 1932 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1933 */ 1934 static int 1935 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1936 { 1937 Authctxt *authctxt = ssh->authctxt; 1938 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1939 char *display_prompt = NULL, *response = NULL; 1940 u_char echo = 0; 1941 u_int num_prompts, i; 1942 int r; 1943 1944 debug2_f("entering"); 1945 1946 if (authctxt == NULL) 1947 fatal_f("no authentication context"); 1948 1949 authctxt->info_req_seen = 1; 1950 1951 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1952 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1953 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1954 goto out; 1955 if (strlen(name) > 0) 1956 logit("%s", name); 1957 if (strlen(inst) > 0) 1958 logit("%s", inst); 1959 1960 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1961 goto out; 1962 /* 1963 * Begin to build info response packet based on prompts requested. 1964 * We commit to providing the correct number of responses, so if 1965 * further on we run into a problem that prevents this, we have to 1966 * be sure and clean this up and send a correct error response. 1967 */ 1968 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1969 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1970 goto out; 1971 1972 debug2_f("num_prompts %d", num_prompts); 1973 for (i = 0; i < num_prompts; i++) { 1974 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1975 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1976 goto out; 1977 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1978 authctxt->server_user, options.host_key_alias ? 1979 options.host_key_alias : authctxt->host, prompt) == -1) 1980 fatal_f("asmprintf failed"); 1981 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1982 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1983 goto out; 1984 freezero(response, strlen(response)); 1985 free(prompt); 1986 free(display_prompt); 1987 display_prompt = response = prompt = NULL; 1988 } 1989 /* done with parsing incoming message. */ 1990 if ((r = sshpkt_get_end(ssh)) != 0 || 1991 (r = sshpkt_add_padding(ssh, 64)) != 0) 1992 goto out; 1993 r = sshpkt_send(ssh); 1994 out: 1995 if (response) 1996 freezero(response, strlen(response)); 1997 free(prompt); 1998 free(display_prompt); 1999 free(name); 2000 free(inst); 2001 free(lang); 2002 return r; 2003 } 2004 2005 static int 2006 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2007 const u_char *data, size_t datalen) 2008 { 2009 struct sshbuf *b; 2010 struct stat st; 2011 pid_t pid; 2012 int r, to[2], from[2], status; 2013 int sock = ssh_packet_get_connection_in(ssh); 2014 u_char rversion = 0, version = 2; 2015 void (*osigchld)(int); 2016 2017 *sigp = NULL; 2018 *lenp = 0; 2019 2020 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2021 error_f("not installed: %s", strerror(errno)); 2022 return -1; 2023 } 2024 if (fflush(stdout) != 0) { 2025 error_f("fflush: %s", strerror(errno)); 2026 return -1; 2027 } 2028 if (pipe(to) == -1) { 2029 error_f("pipe: %s", strerror(errno)); 2030 return -1; 2031 } 2032 if (pipe(from) == -1) { 2033 error_f("pipe: %s", strerror(errno)); 2034 return -1; 2035 } 2036 if ((pid = fork()) == -1) { 2037 error_f("fork: %s", strerror(errno)); 2038 return -1; 2039 } 2040 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2041 if (pid == 0) { 2042 close(from[0]); 2043 if (dup2(from[1], STDOUT_FILENO) == -1) 2044 fatal_f("dup2: %s", strerror(errno)); 2045 close(to[1]); 2046 if (dup2(to[0], STDIN_FILENO) == -1) 2047 fatal_f("dup2: %s", strerror(errno)); 2048 close(from[1]); 2049 close(to[0]); 2050 2051 if (dup2(sock, STDERR_FILENO + 1) == -1) 2052 fatal_f("dup2: %s", strerror(errno)); 2053 sock = STDERR_FILENO + 1; 2054 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2055 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2056 closefrom(sock + 1); 2057 2058 debug3_f("[child] pid=%ld, exec %s", 2059 (long)getpid(), _PATH_SSH_KEY_SIGN); 2060 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2061 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2062 strerror(errno)); 2063 } 2064 close(from[1]); 2065 close(to[0]); 2066 sock = STDERR_FILENO + 1; 2067 2068 if ((b = sshbuf_new()) == NULL) 2069 fatal_f("sshbuf_new failed"); 2070 /* send # of sock, data to be signed */ 2071 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2072 (r = sshbuf_put_string(b, data, datalen)) != 0) 2073 fatal_fr(r, "buffer error"); 2074 if (ssh_msg_send(to[1], version, b) == -1) 2075 fatal_f("couldn't send request"); 2076 sshbuf_reset(b); 2077 r = ssh_msg_recv(from[0], b); 2078 close(from[0]); 2079 close(to[1]); 2080 if (r < 0) { 2081 error_f("no reply"); 2082 goto fail; 2083 } 2084 2085 errno = 0; 2086 while (waitpid(pid, &status, 0) == -1) { 2087 if (errno != EINTR) { 2088 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2089 goto fail; 2090 } 2091 } 2092 if (!WIFEXITED(status)) { 2093 error_f("exited abnormally"); 2094 goto fail; 2095 } 2096 if (WEXITSTATUS(status) != 0) { 2097 error_f("exited with status %d", WEXITSTATUS(status)); 2098 goto fail; 2099 } 2100 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2101 error_fr(r, "buffer error"); 2102 goto fail; 2103 } 2104 if (rversion != version) { 2105 error_f("bad version"); 2106 goto fail; 2107 } 2108 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2109 error_fr(r, "buffer error"); 2110 fail: 2111 ssh_signal(SIGCHLD, osigchld); 2112 sshbuf_free(b); 2113 return -1; 2114 } 2115 ssh_signal(SIGCHLD, osigchld); 2116 sshbuf_free(b); 2117 2118 return 0; 2119 } 2120 2121 static int 2122 userauth_hostbased(struct ssh *ssh) 2123 { 2124 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2125 struct sshkey *private = NULL; 2126 struct sshbuf *b = NULL; 2127 u_char *sig = NULL, *keyblob = NULL; 2128 char *fp = NULL, *chost = NULL, *lname = NULL; 2129 size_t siglen = 0, keylen = 0; 2130 int i, r, success = 0; 2131 2132 if (authctxt->ktypes == NULL) { 2133 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2134 authctxt->ktypes = authctxt->oktypes; 2135 } 2136 2137 /* 2138 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2139 * trying each hostkey that matches the type in turn. 2140 */ 2141 for (;;) { 2142 if (authctxt->active_ktype == NULL) 2143 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2144 if (authctxt->active_ktype == NULL || 2145 *authctxt->active_ktype == '\0') 2146 break; 2147 debug3_f("trying key type %s", authctxt->active_ktype); 2148 2149 /* check for a useful key */ 2150 private = NULL; 2151 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2152 if (authctxt->sensitive->keys[i] == NULL || 2153 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2154 continue; 2155 if (!sshkey_match_keyname_to_sigalgs( 2156 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2157 authctxt->active_ktype)) 2158 continue; 2159 /* we take and free the key */ 2160 private = authctxt->sensitive->keys[i]; 2161 authctxt->sensitive->keys[i] = NULL; 2162 break; 2163 } 2164 /* Found one */ 2165 if (private != NULL) 2166 break; 2167 /* No more keys of this type; advance */ 2168 authctxt->active_ktype = NULL; 2169 } 2170 if (private == NULL) { 2171 free(authctxt->oktypes); 2172 authctxt->oktypes = authctxt->ktypes = NULL; 2173 authctxt->active_ktype = NULL; 2174 debug("No more client hostkeys for hostbased authentication."); 2175 goto out; 2176 } 2177 2178 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2179 SSH_FP_DEFAULT)) == NULL) { 2180 error_f("sshkey_fingerprint failed"); 2181 goto out; 2182 } 2183 debug_f("trying hostkey %s %s using sigalg %s", 2184 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2185 2186 /* figure out a name for the client host */ 2187 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2188 if (lname == NULL) { 2189 error_f("cannot get local ipaddr/name"); 2190 goto out; 2191 } 2192 2193 /* XXX sshbuf_put_stringf? */ 2194 xasprintf(&chost, "%s.", lname); 2195 debug2_f("chost %s", chost); 2196 2197 /* construct data */ 2198 if ((b = sshbuf_new()) == NULL) { 2199 error_f("sshbuf_new failed"); 2200 goto out; 2201 } 2202 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2203 error_fr(r, "sshkey_to_blob"); 2204 goto out; 2205 } 2206 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2207 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2208 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2209 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2210 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2211 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2212 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2213 (r = sshbuf_put_cstring(b, chost)) != 0 || 2214 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2215 error_fr(r, "buffer error"); 2216 goto out; 2217 } 2218 2219 #ifdef DEBUG_PK 2220 sshbuf_dump(b, stderr); 2221 #endif 2222 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2223 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2224 error("sign using hostkey %s %s failed", 2225 sshkey_ssh_name(private), fp); 2226 goto out; 2227 } 2228 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2229 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2230 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2231 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2232 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2233 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2234 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2235 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2236 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2237 (r = sshpkt_send(ssh)) != 0) { 2238 error_fr(r, "packet error"); 2239 goto out; 2240 } 2241 success = 1; 2242 2243 out: 2244 if (sig != NULL) 2245 freezero(sig, siglen); 2246 free(keyblob); 2247 free(lname); 2248 free(fp); 2249 free(chost); 2250 sshkey_free(private); 2251 sshbuf_free(b); 2252 2253 return success; 2254 } 2255 2256 /* find auth method */ 2257 2258 /* 2259 * given auth method name, if configurable options permit this method fill 2260 * in auth_ident field and return true, otherwise return false. 2261 */ 2262 static int 2263 authmethod_is_enabled(Authmethod *method) 2264 { 2265 if (method == NULL) 2266 return 0; 2267 /* return false if options indicate this method is disabled */ 2268 if (method->enabled == NULL || *method->enabled == 0) 2269 return 0; 2270 /* return false if batch mode is enabled but method needs interactive mode */ 2271 if (method->batch_flag != NULL && *method->batch_flag != 0) 2272 return 0; 2273 return 1; 2274 } 2275 2276 static Authmethod * 2277 authmethod_lookup(const char *name) 2278 { 2279 Authmethod *method = NULL; 2280 if (name != NULL) 2281 for (method = authmethods; method->name != NULL; method++) 2282 if (strcmp(name, method->name) == 0) 2283 return method; 2284 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2285 return NULL; 2286 } 2287 2288 /* XXX internal state */ 2289 static Authmethod *current = NULL; 2290 static char *supported = NULL; 2291 static char *preferred = NULL; 2292 2293 /* 2294 * Given the authentication method list sent by the server, return the 2295 * next method we should try. If the server initially sends a nil list, 2296 * use a built-in default list. 2297 */ 2298 static Authmethod * 2299 authmethod_get(char *authlist) 2300 { 2301 char *name = NULL; 2302 u_int next; 2303 2304 /* Use a suitable default if we're passed a nil list. */ 2305 if (authlist == NULL || strlen(authlist) == 0) 2306 authlist = options.preferred_authentications; 2307 2308 if (supported == NULL || strcmp(authlist, supported) != 0) { 2309 debug3("start over, passed a different list %s", authlist); 2310 free(supported); 2311 supported = xstrdup(authlist); 2312 preferred = options.preferred_authentications; 2313 debug3("preferred %s", preferred); 2314 current = NULL; 2315 } else if (current != NULL && authmethod_is_enabled(current)) 2316 return current; 2317 2318 for (;;) { 2319 if ((name = match_list(preferred, supported, &next)) == NULL) { 2320 debug("No more authentication methods to try."); 2321 current = NULL; 2322 return NULL; 2323 } 2324 preferred += next; 2325 debug3("authmethod_lookup %s", name); 2326 debug3("remaining preferred: %s", preferred); 2327 if ((current = authmethod_lookup(name)) != NULL && 2328 authmethod_is_enabled(current)) { 2329 debug3("authmethod_is_enabled %s", name); 2330 debug("Next authentication method: %s", name); 2331 free(name); 2332 return current; 2333 } 2334 free(name); 2335 } 2336 } 2337 2338 static char * 2339 authmethods_get(void) 2340 { 2341 Authmethod *method = NULL; 2342 struct sshbuf *b; 2343 char *list; 2344 int r; 2345 2346 if ((b = sshbuf_new()) == NULL) 2347 fatal_f("sshbuf_new failed"); 2348 for (method = authmethods; method->name != NULL; method++) { 2349 if (authmethod_is_enabled(method)) { 2350 if ((r = sshbuf_putf(b, "%s%s", 2351 sshbuf_len(b) ? "," : "", method->name)) != 0) 2352 fatal_fr(r, "buffer error"); 2353 } 2354 } 2355 if ((list = sshbuf_dup_string(b)) == NULL) 2356 fatal_f("sshbuf_dup_string failed"); 2357 sshbuf_free(b); 2358 return list; 2359 } 2360