1 /* $OpenBSD: sshconnect2.c,v 1.367 2023/08/01 08:15:04 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <limits.h> 37 #include <netdb.h> 38 #include <pwd.h> 39 #include <signal.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdarg.h> 43 #include <unistd.h> 44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 45 #include <vis.h> 46 #endif 47 48 #include "openbsd-compat/sys-queue.h" 49 50 #include "xmalloc.h" 51 #include "ssh.h" 52 #include "ssh2.h" 53 #include "sshbuf.h" 54 #include "packet.h" 55 #include "compat.h" 56 #include "cipher.h" 57 #include "sshkey.h" 58 #include "kex.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 #include "ssh-sk.h" 76 #include "sk-api.h" 77 78 #ifdef GSSAPI 79 #include "ssh-gss.h" 80 #endif 81 82 /* import */ 83 extern char *client_version_string; 84 extern char *server_version_string; 85 extern Options options; 86 87 /* 88 * SSH2 key exchange 89 */ 90 91 static char *xxx_host; 92 static struct sockaddr *xxx_hostaddr; 93 static const struct ssh_conn_info *xxx_conn_info; 94 95 static int 96 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 97 { 98 int r; 99 100 if ((r = sshkey_check_rsa_length(hostkey, 101 options.required_rsa_size)) != 0) 102 fatal_r(r, "Bad server host key"); 103 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 104 xxx_conn_info) == -1) 105 fatal("Host key verification failed."); 106 return 0; 107 } 108 109 /* Returns the first item from a comma-separated algorithm list */ 110 static char * 111 first_alg(const char *algs) 112 { 113 char *ret, *cp; 114 115 ret = xstrdup(algs); 116 if ((cp = strchr(ret, ',')) != NULL) 117 *cp = '\0'; 118 return ret; 119 } 120 121 static char * 122 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 123 const struct ssh_conn_info *cinfo) 124 { 125 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 126 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 127 size_t maxlen; 128 struct hostkeys *hostkeys = NULL; 129 int ktype; 130 u_int i; 131 132 /* Find all hostkeys for this hostname */ 133 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 134 hostkeys = init_hostkeys(); 135 for (i = 0; i < options.num_user_hostfiles; i++) 136 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 137 for (i = 0; i < options.num_system_hostfiles; i++) { 138 load_hostkeys(hostkeys, hostname, 139 options.system_hostfiles[i], 0); 140 } 141 if (options.known_hosts_command != NULL) { 142 load_hostkeys_command(hostkeys, options.known_hosts_command, 143 "ORDER", cinfo, NULL, host); 144 } 145 /* 146 * If a plain public key exists that matches the type of the best 147 * preference HostkeyAlgorithms, then use the whole list as is. 148 * Note that we ignore whether the best preference algorithm is a 149 * certificate type, as sshconnect.c will downgrade certs to 150 * plain keys if necessary. 151 */ 152 best = first_alg(options.hostkeyalgorithms); 153 if (lookup_key_in_hostkeys_by_type(hostkeys, 154 sshkey_type_plain(sshkey_type_from_name(best)), 155 sshkey_ecdsa_nid_from_name(best), NULL)) { 156 debug3_f("have matching best-preference key type %s, " 157 "using HostkeyAlgorithms verbatim", best); 158 ret = xstrdup(options.hostkeyalgorithms); 159 goto out; 160 } 161 162 /* 163 * Otherwise, prefer the host key algorithms that match known keys 164 * while keeping the ordering of HostkeyAlgorithms as much as possible. 165 */ 166 oavail = avail = xstrdup(options.hostkeyalgorithms); 167 maxlen = strlen(avail) + 1; 168 first = xmalloc(maxlen); 169 last = xmalloc(maxlen); 170 *first = *last = '\0'; 171 172 #define ALG_APPEND(to, from) \ 173 do { \ 174 if (*to != '\0') \ 175 strlcat(to, ",", maxlen); \ 176 strlcat(to, from, maxlen); \ 177 } while (0) 178 179 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 180 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 181 fatal_f("unknown alg %s", alg); 182 /* 183 * If we have a @cert-authority marker in known_hosts then 184 * prefer all certificate algorithms. 185 */ 186 if (sshkey_type_is_cert(ktype) && 187 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 188 ALG_APPEND(first, alg); 189 continue; 190 } 191 /* If the key appears in known_hosts then prefer it */ 192 if (lookup_key_in_hostkeys_by_type(hostkeys, 193 sshkey_type_plain(ktype), 194 sshkey_ecdsa_nid_from_name(alg), NULL)) { 195 ALG_APPEND(first, alg); 196 continue; 197 } 198 /* Otherwise, put it last */ 199 ALG_APPEND(last, alg); 200 } 201 #undef ALG_APPEND 202 xasprintf(&ret, "%s%s%s", first, 203 (*first == '\0' || *last == '\0') ? "" : ",", last); 204 if (*first != '\0') 205 debug3_f("prefer hostkeyalgs: %s", first); 206 else 207 debug3_f("no algorithms matched; accept original"); 208 out: 209 free(best); 210 free(first); 211 free(last); 212 free(hostname); 213 free(oavail); 214 free_hostkeys(hostkeys); 215 216 return ret; 217 } 218 219 void 220 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 221 const struct ssh_conn_info *cinfo) 222 { 223 char *myproposal[PROPOSAL_MAX]; 224 char *s, *all_key, *hkalgs = NULL; 225 int r, use_known_hosts_order = 0; 226 227 xxx_host = host; 228 xxx_hostaddr = hostaddr; 229 xxx_conn_info = cinfo; 230 231 if (options.rekey_limit || options.rekey_interval) 232 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 233 options.rekey_interval); 234 235 /* 236 * If the user has not specified HostkeyAlgorithms, or has only 237 * appended or removed algorithms from that list then prefer algorithms 238 * that are in the list that are supported by known_hosts keys. 239 */ 240 if (options.hostkeyalgorithms == NULL || 241 options.hostkeyalgorithms[0] == '-' || 242 options.hostkeyalgorithms[0] == '+') 243 use_known_hosts_order = 1; 244 245 /* Expand or fill in HostkeyAlgorithms */ 246 all_key = sshkey_alg_list(0, 0, 1, ','); 247 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 248 kex_default_pk_alg(), all_key)) != 0) 249 fatal_fr(r, "kex_assemble_namelist"); 250 free(all_key); 251 252 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 253 fatal_f("kex_names_cat"); 254 255 if (use_known_hosts_order) 256 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 257 258 kex_proposal_populate_entries(ssh, myproposal, s, options.ciphers, 259 options.macs, compression_alg_list(options.compression), 260 hkalgs ? hkalgs : options.hostkeyalgorithms); 261 262 free(hkalgs); 263 264 /* start key exchange */ 265 if ((r = kex_setup(ssh, myproposal)) != 0) 266 fatal_r(r, "kex_setup"); 267 #ifdef WITH_OPENSSL 268 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 270 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 272 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 273 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 274 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 275 # ifdef OPENSSL_HAS_ECC 276 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 277 # endif 278 #endif 279 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 280 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 281 ssh->kex->verify_host_key=&verify_host_key_callback; 282 283 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 284 285 /* remove ext-info from the KEX proposals for rekeying */ 286 free(myproposal[PROPOSAL_KEX_ALGS]); 287 myproposal[PROPOSAL_KEX_ALGS] = 288 compat_kex_proposal(ssh, options.kex_algorithms); 289 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 290 fatal_r(r, "kex_prop2buf"); 291 292 #ifdef DEBUG_KEXDH 293 /* send 1st encrypted/maced/compressed message */ 294 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 295 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 296 (r = sshpkt_send(ssh)) != 0 || 297 (r = ssh_packet_write_wait(ssh)) != 0) 298 fatal_fr(r, "send packet"); 299 #endif 300 kex_proposal_free_entries(myproposal); 301 } 302 303 /* 304 * Authenticate user 305 */ 306 307 typedef struct cauthctxt Authctxt; 308 typedef struct cauthmethod Authmethod; 309 typedef struct identity Identity; 310 typedef struct idlist Idlist; 311 312 struct identity { 313 TAILQ_ENTRY(identity) next; 314 int agent_fd; /* >=0 if agent supports key */ 315 struct sshkey *key; /* public/private key */ 316 char *filename; /* comment for agent-only keys */ 317 int tried; 318 int isprivate; /* key points to the private key */ 319 int userprovided; 320 }; 321 TAILQ_HEAD(idlist, identity); 322 323 struct cauthctxt { 324 const char *server_user; 325 const char *local_user; 326 const char *host; 327 const char *service; 328 struct cauthmethod *method; 329 sig_atomic_t success; 330 char *authlist; 331 #ifdef GSSAPI 332 /* gssapi */ 333 gss_OID_set gss_supported_mechs; 334 u_int mech_tried; 335 #endif 336 /* pubkey */ 337 struct idlist keys; 338 int agent_fd; 339 /* hostbased */ 340 Sensitive *sensitive; 341 char *oktypes, *ktypes; 342 const char *active_ktype; 343 /* kbd-interactive */ 344 int info_req_seen; 345 int attempt_kbdint; 346 /* password */ 347 int attempt_passwd; 348 /* generic */ 349 void *methoddata; 350 }; 351 352 struct cauthmethod { 353 char *name; /* string to compare against server's list */ 354 int (*userauth)(struct ssh *ssh); 355 void (*cleanup)(struct ssh *ssh); 356 int *enabled; /* flag in option struct that enables method */ 357 int *batch_flag; /* flag in option struct that disables method */ 358 }; 359 360 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 361 static int input_userauth_success(int, u_int32_t, struct ssh *); 362 static int input_userauth_failure(int, u_int32_t, struct ssh *); 363 static int input_userauth_banner(int, u_int32_t, struct ssh *); 364 static int input_userauth_error(int, u_int32_t, struct ssh *); 365 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 366 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 367 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 368 369 static int userauth_none(struct ssh *); 370 static int userauth_pubkey(struct ssh *); 371 static int userauth_passwd(struct ssh *); 372 static int userauth_kbdint(struct ssh *); 373 static int userauth_hostbased(struct ssh *); 374 375 #ifdef GSSAPI 376 static int userauth_gssapi(struct ssh *); 377 static void userauth_gssapi_cleanup(struct ssh *); 378 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 379 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 380 static int input_gssapi_error(int, u_int32_t, struct ssh *); 381 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 382 #endif 383 384 void userauth(struct ssh *, char *); 385 386 static void pubkey_cleanup(struct ssh *); 387 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 388 static void pubkey_prepare(struct ssh *, Authctxt *); 389 static void pubkey_reset(Authctxt *); 390 static struct sshkey *load_identity_file(Identity *); 391 392 static Authmethod *authmethod_get(char *authlist); 393 static Authmethod *authmethod_lookup(const char *name); 394 static char *authmethods_get(void); 395 396 Authmethod authmethods[] = { 397 #ifdef GSSAPI 398 {"gssapi-with-mic", 399 userauth_gssapi, 400 userauth_gssapi_cleanup, 401 &options.gss_authentication, 402 NULL}, 403 #endif 404 {"hostbased", 405 userauth_hostbased, 406 NULL, 407 &options.hostbased_authentication, 408 NULL}, 409 {"publickey", 410 userauth_pubkey, 411 NULL, 412 &options.pubkey_authentication, 413 NULL}, 414 {"keyboard-interactive", 415 userauth_kbdint, 416 NULL, 417 &options.kbd_interactive_authentication, 418 &options.batch_mode}, 419 {"password", 420 userauth_passwd, 421 NULL, 422 &options.password_authentication, 423 &options.batch_mode}, 424 {"none", 425 userauth_none, 426 NULL, 427 NULL, 428 NULL}, 429 {NULL, NULL, NULL, NULL, NULL} 430 }; 431 432 void 433 ssh_userauth2(struct ssh *ssh, const char *local_user, 434 const char *server_user, char *host, Sensitive *sensitive) 435 { 436 Authctxt authctxt; 437 int r; 438 439 if (options.preferred_authentications == NULL) 440 options.preferred_authentications = authmethods_get(); 441 442 /* setup authentication context */ 443 memset(&authctxt, 0, sizeof(authctxt)); 444 authctxt.server_user = server_user; 445 authctxt.local_user = local_user; 446 authctxt.host = host; 447 authctxt.service = "ssh-connection"; /* service name */ 448 authctxt.success = 0; 449 authctxt.method = authmethod_lookup("none"); 450 authctxt.authlist = NULL; 451 authctxt.methoddata = NULL; 452 authctxt.sensitive = sensitive; 453 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 454 authctxt.info_req_seen = 0; 455 authctxt.attempt_kbdint = 0; 456 authctxt.attempt_passwd = 0; 457 #if GSSAPI 458 authctxt.gss_supported_mechs = NULL; 459 authctxt.mech_tried = 0; 460 #endif 461 authctxt.agent_fd = -1; 462 pubkey_prepare(ssh, &authctxt); 463 if (authctxt.method == NULL) { 464 fatal_f("internal error: cannot send userauth none request"); 465 } 466 467 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 468 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 469 (r = sshpkt_send(ssh)) != 0) 470 fatal_fr(r, "send packet"); 471 472 ssh->authctxt = &authctxt; 473 ssh_dispatch_init(ssh, &input_userauth_error); 474 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 475 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 476 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 477 pubkey_cleanup(ssh); 478 ssh->authctxt = NULL; 479 480 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 481 482 if (!authctxt.success) 483 fatal("Authentication failed."); 484 if (ssh_packet_connection_is_on_socket(ssh)) { 485 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 486 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 487 authctxt.method->name); 488 } else { 489 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 490 authctxt.method->name); 491 } 492 } 493 494 static int 495 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 496 { 497 int r; 498 499 if (ssh_packet_remaining(ssh) > 0) { 500 char *reply; 501 502 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 503 goto out; 504 debug2("service_accept: %s", reply); 505 free(reply); 506 } else { 507 debug2("buggy server: service_accept w/o service"); 508 } 509 if ((r = sshpkt_get_end(ssh)) != 0) 510 goto out; 511 debug("SSH2_MSG_SERVICE_ACCEPT received"); 512 513 /* initial userauth request */ 514 userauth_none(ssh); 515 516 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 517 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 519 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 520 r = 0; 521 out: 522 return r; 523 } 524 525 void 526 userauth(struct ssh *ssh, char *authlist) 527 { 528 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 529 530 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 531 authctxt->method->cleanup(ssh); 532 533 free(authctxt->methoddata); 534 authctxt->methoddata = NULL; 535 if (authlist == NULL) { 536 authlist = authctxt->authlist; 537 } else { 538 free(authctxt->authlist); 539 authctxt->authlist = authlist; 540 } 541 for (;;) { 542 Authmethod *method = authmethod_get(authlist); 543 if (method == NULL) 544 fatal("%s@%s: Permission denied (%s).", 545 authctxt->server_user, authctxt->host, authlist); 546 authctxt->method = method; 547 548 /* reset the per method handler */ 549 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 550 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 551 552 /* and try new method */ 553 if (method->userauth(ssh) != 0) { 554 debug2("we sent a %s packet, wait for reply", method->name); 555 break; 556 } else { 557 debug2("we did not send a packet, disable method"); 558 method->enabled = NULL; 559 } 560 } 561 } 562 563 static int 564 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 565 { 566 fatal_f("bad message during authentication: type %d", type); 567 return 0; 568 } 569 570 static int 571 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 572 { 573 char *msg = NULL; 574 size_t len; 575 int r; 576 577 debug3_f("entering"); 578 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 579 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 580 goto out; 581 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 582 fmprintf(stderr, "%s", msg); 583 r = 0; 584 out: 585 free(msg); 586 return r; 587 } 588 589 static int 590 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 591 { 592 Authctxt *authctxt = ssh->authctxt; 593 594 if (authctxt == NULL) 595 fatal_f("no authentication context"); 596 free(authctxt->authlist); 597 authctxt->authlist = NULL; 598 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 599 authctxt->method->cleanup(ssh); 600 free(authctxt->methoddata); 601 authctxt->methoddata = NULL; 602 authctxt->success = 1; /* break out */ 603 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 604 return 0; 605 } 606 607 #if 0 608 static int 609 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 610 { 611 Authctxt *authctxt = ssh->authctxt; 612 613 if (authctxt == NULL) 614 fatal_f("no authentication context"); 615 616 fatal("Unexpected authentication success during %s.", 617 authctxt->method->name); 618 return 0; 619 } 620 #endif 621 622 static int 623 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 624 { 625 Authctxt *authctxt = ssh->authctxt; 626 char *authlist = NULL; 627 u_char partial; 628 629 if (authctxt == NULL) 630 fatal("input_userauth_failure: no authentication context"); 631 632 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 633 sshpkt_get_u8(ssh, &partial) != 0 || 634 sshpkt_get_end(ssh) != 0) 635 goto out; 636 637 if (partial != 0) { 638 verbose("Authenticated using \"%s\" with partial success.", 639 authctxt->method->name); 640 /* reset state */ 641 pubkey_reset(authctxt); 642 } 643 debug("Authentications that can continue: %s", authlist); 644 645 userauth(ssh, authlist); 646 authlist = NULL; 647 out: 648 free(authlist); 649 return 0; 650 } 651 652 /* 653 * Format an identity for logging including filename, key type, fingerprint 654 * and location (agent, etc.). Caller must free. 655 */ 656 static char * 657 format_identity(Identity *id) 658 { 659 char *fp = NULL, *ret = NULL; 660 const char *note = ""; 661 662 if (id->key != NULL) { 663 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 664 SSH_FP_DEFAULT); 665 } 666 if (id->key) { 667 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 668 note = " token"; 669 else if (sshkey_is_sk(id->key)) 670 note = " authenticator"; 671 } 672 xasprintf(&ret, "%s %s%s%s%s%s%s", 673 id->filename, 674 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 675 fp ? fp : "", 676 id->userprovided ? " explicit" : "", note, 677 id->agent_fd != -1 ? " agent" : ""); 678 free(fp); 679 return ret; 680 } 681 682 static int 683 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 684 { 685 Authctxt *authctxt = ssh->authctxt; 686 struct sshkey *key = NULL; 687 Identity *id = NULL; 688 int pktype, found = 0, sent = 0; 689 size_t blen; 690 char *pkalg = NULL, *fp = NULL, *ident = NULL; 691 u_char *pkblob = NULL; 692 int r; 693 694 if (authctxt == NULL) 695 fatal("input_userauth_pk_ok: no authentication context"); 696 697 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 698 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 699 (r = sshpkt_get_end(ssh)) != 0) 700 goto done; 701 702 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 703 debug_f("server sent unknown pkalg %s", pkalg); 704 goto done; 705 } 706 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 707 debug_r(r, "no key from blob. pkalg %s", pkalg); 708 goto done; 709 } 710 if (key->type != pktype) { 711 error("input_userauth_pk_ok: type mismatch " 712 "for decoded key (received %d, expected %d)", 713 key->type, pktype); 714 goto done; 715 } 716 717 /* 718 * search keys in the reverse order, because last candidate has been 719 * moved to the end of the queue. this also avoids confusion by 720 * duplicate keys 721 */ 722 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 723 if (sshkey_equal(key, id->key)) { 724 found = 1; 725 break; 726 } 727 } 728 if (!found || id == NULL) { 729 fp = sshkey_fingerprint(key, options.fingerprint_hash, 730 SSH_FP_DEFAULT); 731 error_f("server replied with unknown key: %s %s", 732 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 733 goto done; 734 } 735 ident = format_identity(id); 736 debug("Server accepts key: %s", ident); 737 sent = sign_and_send_pubkey(ssh, id); 738 r = 0; 739 done: 740 sshkey_free(key); 741 free(ident); 742 free(fp); 743 free(pkalg); 744 free(pkblob); 745 746 /* try another method if we did not send a packet */ 747 if (r == 0 && sent == 0) 748 userauth(ssh, NULL); 749 return r; 750 } 751 752 #ifdef GSSAPI 753 static int 754 userauth_gssapi(struct ssh *ssh) 755 { 756 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 757 Gssctxt *gssctxt = NULL; 758 OM_uint32 min; 759 int r, ok = 0; 760 gss_OID mech = NULL; 761 762 /* Try one GSSAPI method at a time, rather than sending them all at 763 * once. */ 764 765 if (authctxt->gss_supported_mechs == NULL) 766 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 767 768 /* Check to see whether the mechanism is usable before we offer it */ 769 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 770 !ok) { 771 mech = &authctxt->gss_supported_mechs-> 772 elements[authctxt->mech_tried]; 773 /* My DER encoding requires length<128 */ 774 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 775 mech, authctxt->host)) { 776 ok = 1; /* Mechanism works */ 777 } else { 778 authctxt->mech_tried++; 779 } 780 } 781 782 if (!ok || mech == NULL) 783 return 0; 784 785 authctxt->methoddata=(void *)gssctxt; 786 787 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 788 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 789 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 790 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 791 (r = sshpkt_put_u32(ssh, 1)) != 0 || 792 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 793 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 794 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 795 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 796 (r = sshpkt_send(ssh)) != 0) 797 fatal_fr(r, "send packet"); 798 799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 800 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 801 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 802 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 803 804 authctxt->mech_tried++; /* Move along to next candidate */ 805 806 return 1; 807 } 808 809 static void 810 userauth_gssapi_cleanup(struct ssh *ssh) 811 { 812 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 813 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 814 815 ssh_gssapi_delete_ctx(&gssctxt); 816 authctxt->methoddata = NULL; 817 818 free(authctxt->gss_supported_mechs); 819 authctxt->gss_supported_mechs = NULL; 820 } 821 822 static OM_uint32 823 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 824 { 825 Authctxt *authctxt = ssh->authctxt; 826 Gssctxt *gssctxt = authctxt->methoddata; 827 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 828 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 829 gss_buffer_desc gssbuf; 830 OM_uint32 status, ms, flags; 831 int r; 832 833 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 834 recv_tok, &send_tok, &flags); 835 836 if (send_tok.length > 0) { 837 u_char type = GSS_ERROR(status) ? 838 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 839 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 840 841 if ((r = sshpkt_start(ssh, type)) != 0 || 842 (r = sshpkt_put_string(ssh, send_tok.value, 843 send_tok.length)) != 0 || 844 (r = sshpkt_send(ssh)) != 0) 845 fatal_fr(r, "send %u packet", type); 846 847 gss_release_buffer(&ms, &send_tok); 848 } 849 850 if (status == GSS_S_COMPLETE) { 851 /* send either complete or MIC, depending on mechanism */ 852 if (!(flags & GSS_C_INTEG_FLAG)) { 853 if ((r = sshpkt_start(ssh, 854 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 855 (r = sshpkt_send(ssh)) != 0) 856 fatal_fr(r, "send completion"); 857 } else { 858 struct sshbuf *b; 859 860 if ((b = sshbuf_new()) == NULL) 861 fatal_f("sshbuf_new failed"); 862 ssh_gssapi_buildmic(b, authctxt->server_user, 863 authctxt->service, "gssapi-with-mic", 864 ssh->kex->session_id); 865 866 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 867 fatal_f("sshbuf_mutable_ptr failed"); 868 gssbuf.length = sshbuf_len(b); 869 870 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 871 872 if (!GSS_ERROR(status)) { 873 if ((r = sshpkt_start(ssh, 874 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 875 (r = sshpkt_put_string(ssh, mic.value, 876 mic.length)) != 0 || 877 (r = sshpkt_send(ssh)) != 0) 878 fatal_fr(r, "send MIC"); 879 } 880 881 sshbuf_free(b); 882 gss_release_buffer(&ms, &mic); 883 } 884 } 885 886 return status; 887 } 888 889 static int 890 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 891 { 892 Authctxt *authctxt = ssh->authctxt; 893 Gssctxt *gssctxt; 894 size_t oidlen; 895 u_char *oidv = NULL; 896 int r; 897 898 if (authctxt == NULL) 899 fatal("input_gssapi_response: no authentication context"); 900 gssctxt = authctxt->methoddata; 901 902 /* Setup our OID */ 903 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 904 goto done; 905 906 if (oidlen <= 2 || 907 oidv[0] != SSH_GSS_OIDTYPE || 908 oidv[1] != oidlen - 2) { 909 debug("Badly encoded mechanism OID received"); 910 userauth(ssh, NULL); 911 goto ok; 912 } 913 914 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 915 fatal("Server returned different OID than expected"); 916 917 if ((r = sshpkt_get_end(ssh)) != 0) 918 goto done; 919 920 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 921 /* Start again with next method on list */ 922 debug("Trying to start again"); 923 userauth(ssh, NULL); 924 goto ok; 925 } 926 ok: 927 r = 0; 928 done: 929 free(oidv); 930 return r; 931 } 932 933 static int 934 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 935 { 936 Authctxt *authctxt = ssh->authctxt; 937 gss_buffer_desc recv_tok; 938 u_char *p = NULL; 939 size_t len; 940 OM_uint32 status; 941 int r; 942 943 if (authctxt == NULL) 944 fatal("input_gssapi_response: no authentication context"); 945 946 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 947 (r = sshpkt_get_end(ssh)) != 0) 948 goto out; 949 950 recv_tok.value = p; 951 recv_tok.length = len; 952 status = process_gssapi_token(ssh, &recv_tok); 953 954 /* Start again with the next method in the list */ 955 if (GSS_ERROR(status)) { 956 userauth(ssh, NULL); 957 /* ok */ 958 } 959 r = 0; 960 out: 961 free(p); 962 return r; 963 } 964 965 static int 966 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 967 { 968 Authctxt *authctxt = ssh->authctxt; 969 Gssctxt *gssctxt; 970 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 971 gss_buffer_desc recv_tok; 972 OM_uint32 ms; 973 u_char *p = NULL; 974 size_t len; 975 int r; 976 977 if (authctxt == NULL) 978 fatal("input_gssapi_response: no authentication context"); 979 gssctxt = authctxt->methoddata; 980 981 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 982 (r = sshpkt_get_end(ssh)) != 0) { 983 free(p); 984 return r; 985 } 986 987 /* Stick it into GSSAPI and see what it says */ 988 recv_tok.value = p; 989 recv_tok.length = len; 990 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 991 &recv_tok, &send_tok, NULL); 992 free(p); 993 gss_release_buffer(&ms, &send_tok); 994 995 /* Server will be returning a failed packet after this one */ 996 return 0; 997 } 998 999 static int 1000 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1001 { 1002 char *msg = NULL; 1003 char *lang = NULL; 1004 int r; 1005 1006 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1007 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1008 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1009 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1010 goto out; 1011 r = sshpkt_get_end(ssh); 1012 debug("Server GSSAPI Error:\n%s", msg); 1013 out: 1014 free(msg); 1015 free(lang); 1016 return r; 1017 } 1018 #endif /* GSSAPI */ 1019 1020 static int 1021 userauth_none(struct ssh *ssh) 1022 { 1023 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1024 int r; 1025 1026 /* initial userauth request */ 1027 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1028 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1029 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1030 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1031 (r = sshpkt_send(ssh)) != 0) 1032 fatal_fr(r, "send packet"); 1033 return 1; 1034 } 1035 1036 static int 1037 userauth_passwd(struct ssh *ssh) 1038 { 1039 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1040 char *password, *prompt = NULL; 1041 const char *host = options.host_key_alias ? options.host_key_alias : 1042 authctxt->host; 1043 int r; 1044 1045 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1046 return 0; 1047 1048 if (authctxt->attempt_passwd != 1) 1049 error("Permission denied, please try again."); 1050 1051 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1052 password = read_passphrase(prompt, 0); 1053 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1056 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1057 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1058 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1059 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1060 (r = sshpkt_send(ssh)) != 0) 1061 fatal_fr(r, "send packet"); 1062 1063 free(prompt); 1064 if (password != NULL) 1065 freezero(password, strlen(password)); 1066 1067 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1068 &input_userauth_passwd_changereq); 1069 1070 return 1; 1071 } 1072 1073 /* 1074 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1075 */ 1076 static int 1077 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1078 { 1079 Authctxt *authctxt = ssh->authctxt; 1080 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1081 char prompt[256]; 1082 const char *host; 1083 int r; 1084 1085 debug2("input_userauth_passwd_changereq"); 1086 1087 if (authctxt == NULL) 1088 fatal("input_userauth_passwd_changereq: " 1089 "no authentication context"); 1090 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1091 1092 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1093 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1094 goto out; 1095 if (strlen(info) > 0) 1096 logit("%s", info); 1097 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1098 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1099 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1100 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1101 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1102 goto out; 1103 1104 snprintf(prompt, sizeof(prompt), 1105 "Enter %.30s@%.128s's old password: ", 1106 authctxt->server_user, host); 1107 password = read_passphrase(prompt, 0); 1108 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1109 goto out; 1110 1111 freezero(password, strlen(password)); 1112 password = NULL; 1113 while (password == NULL) { 1114 snprintf(prompt, sizeof(prompt), 1115 "Enter %.30s@%.128s's new password: ", 1116 authctxt->server_user, host); 1117 password = read_passphrase(prompt, RP_ALLOW_EOF); 1118 if (password == NULL) { 1119 /* bail out */ 1120 r = 0; 1121 goto out; 1122 } 1123 snprintf(prompt, sizeof(prompt), 1124 "Retype %.30s@%.128s's new password: ", 1125 authctxt->server_user, host); 1126 retype = read_passphrase(prompt, 0); 1127 if (strcmp(password, retype) != 0) { 1128 freezero(password, strlen(password)); 1129 logit("Mismatch; try again, EOF to quit."); 1130 password = NULL; 1131 } 1132 freezero(retype, strlen(retype)); 1133 } 1134 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1135 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1136 (r = sshpkt_send(ssh)) != 0) 1137 goto out; 1138 1139 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1140 &input_userauth_passwd_changereq); 1141 r = 0; 1142 out: 1143 if (password) 1144 freezero(password, strlen(password)); 1145 free(info); 1146 free(lang); 1147 return r; 1148 } 1149 1150 /* 1151 * Select an algorithm for publickey signatures. 1152 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1153 * 1154 * Call with ssh==NULL to ignore server-sig-algs extension list and 1155 * only attempt with the key's base signature type. 1156 */ 1157 static char * 1158 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1159 { 1160 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1161 const char *server_sig_algs; 1162 1163 /* 1164 * The signature algorithm will only differ from the key algorithm 1165 * for RSA keys/certs and when the server advertises support for 1166 * newer (SHA2) algorithms. 1167 */ 1168 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1169 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1170 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1171 /* Filter base key signature alg against our configuration */ 1172 return match_list(sshkey_ssh_name(key), 1173 options.pubkey_accepted_algos, NULL); 1174 } 1175 1176 /* 1177 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1178 * fails to advertise it via SSH2_MSG_EXT_INFO. 1179 */ 1180 server_sig_algs = ssh->kex->server_sig_algs; 1181 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1182 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1183 1184 /* 1185 * For RSA keys/certs, since these might have a different sig type: 1186 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1187 * that also appears in the supported signature algorithms list from 1188 * the server. 1189 */ 1190 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1191 while ((cp = strsep(&allowed, ",")) != NULL) { 1192 if (sshkey_type_from_name(cp) != key->type) 1193 continue; 1194 tmp = match_list(sshkey_sigalg_by_name(cp), 1195 server_sig_algs, NULL); 1196 if (tmp != NULL) 1197 alg = xstrdup(cp); 1198 free(tmp); 1199 if (alg != NULL) 1200 break; 1201 } 1202 free(oallowed); 1203 return alg; 1204 } 1205 1206 static int 1207 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1208 const u_char *data, size_t datalen, u_int compat, const char *alg) 1209 { 1210 struct sshkey *sign_key = NULL, *prv = NULL; 1211 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1212 struct notifier_ctx *notifier = NULL; 1213 char *fp = NULL, *pin = NULL, *prompt = NULL; 1214 1215 *sigp = NULL; 1216 *lenp = 0; 1217 1218 /* The agent supports this key. */ 1219 if (id->key != NULL && id->agent_fd != -1) { 1220 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1221 data, datalen, alg, compat); 1222 } 1223 1224 /* 1225 * We have already loaded the private key or the private key is 1226 * stored in external hardware. 1227 */ 1228 if (id->key != NULL && 1229 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1230 sign_key = id->key; 1231 is_agent = 1; 1232 } else { 1233 /* Load the private key from the file. */ 1234 if ((prv = load_identity_file(id)) == NULL) 1235 return SSH_ERR_KEY_NOT_FOUND; 1236 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1237 error_f("private key %s contents do not match public", 1238 id->filename); 1239 r = SSH_ERR_KEY_NOT_FOUND; 1240 goto out; 1241 } 1242 sign_key = prv; 1243 } 1244 retry_pin: 1245 /* Prompt for touch for non-agent FIDO keys that request UP */ 1246 if (!is_agent && sshkey_is_sk(sign_key) && 1247 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1248 /* XXX should batch mode just skip these? */ 1249 if ((fp = sshkey_fingerprint(sign_key, 1250 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1251 fatal_f("fingerprint failed"); 1252 notifier = notify_start(options.batch_mode, 1253 "Confirm user presence for key %s %s", 1254 sshkey_type(sign_key), fp); 1255 free(fp); 1256 } 1257 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1258 alg, options.sk_provider, pin, compat)) != 0) { 1259 debug_fr(r, "sshkey_sign"); 1260 if (!retried && pin == NULL && !is_agent && 1261 sshkey_is_sk(sign_key) && 1262 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1263 notify_complete(notifier, NULL); 1264 notifier = NULL; 1265 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1266 sshkey_type(sign_key), id->filename); 1267 pin = read_passphrase(prompt, 0); 1268 retried = 1; 1269 goto retry_pin; 1270 } 1271 goto out; 1272 } 1273 1274 /* 1275 * PKCS#11 tokens may not support all signature algorithms, 1276 * so check what we get back. 1277 */ 1278 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1279 debug_fr(r, "sshkey_check_sigtype"); 1280 goto out; 1281 } 1282 /* success */ 1283 r = 0; 1284 out: 1285 free(prompt); 1286 if (pin != NULL) 1287 freezero(pin, strlen(pin)); 1288 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1289 sshkey_free(prv); 1290 return r; 1291 } 1292 1293 static int 1294 id_filename_matches(Identity *id, Identity *private_id) 1295 { 1296 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1297 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1298 size_t i, slen; 1299 1300 if (strcmp(id->filename, private_id->filename) == 0) 1301 return 1; 1302 for (i = 0; suffixes[i]; i++) { 1303 slen = strlen(suffixes[i]); 1304 if (len > slen && plen == len - slen && 1305 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1306 memcmp(id->filename, private_id->filename, plen) == 0) 1307 return 1; 1308 } 1309 return 0; 1310 } 1311 1312 static int 1313 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1314 { 1315 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1316 struct sshbuf *b = NULL; 1317 Identity *private_id, *sign_id = NULL; 1318 u_char *signature = NULL; 1319 size_t slen = 0, skip = 0; 1320 int r, fallback_sigtype, sent = 0; 1321 char *alg = NULL, *fp = NULL; 1322 const char *loc = "", *method = "publickey"; 1323 int hostbound = 0; 1324 1325 /* prefer host-bound pubkey signatures if supported by server */ 1326 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1327 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1328 hostbound = 1; 1329 method = "publickey-hostbound-v00@openssh.com"; 1330 } 1331 1332 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1333 SSH_FP_DEFAULT)) == NULL) 1334 return 0; 1335 1336 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1337 1338 /* 1339 * If the key is an certificate, try to find a matching private key 1340 * and use it to complete the signature. 1341 * If no such private key exists, fall back to trying the certificate 1342 * key itself in case it has a private half already loaded. 1343 * This will try to set sign_id to the private key that will perform 1344 * the signature. 1345 */ 1346 if (sshkey_is_cert(id->key)) { 1347 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1348 if (sshkey_equal_public(id->key, private_id->key) && 1349 id->key->type != private_id->key->type) { 1350 sign_id = private_id; 1351 break; 1352 } 1353 } 1354 /* 1355 * Exact key matches are preferred, but also allow 1356 * filename matches for non-PKCS#11/agent keys that 1357 * didn't load public keys. This supports the case 1358 * of keeping just a private key file and public 1359 * certificate on disk. 1360 */ 1361 if (sign_id == NULL && 1362 !id->isprivate && id->agent_fd == -1 && 1363 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1364 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1365 if (private_id->key == NULL && 1366 id_filename_matches(id, private_id)) { 1367 sign_id = private_id; 1368 break; 1369 } 1370 } 1371 } 1372 if (sign_id != NULL) { 1373 debug2_f("using private key \"%s\"%s for " 1374 "certificate", sign_id->filename, 1375 sign_id->agent_fd != -1 ? " from agent" : ""); 1376 } else { 1377 debug_f("no separate private key for certificate " 1378 "\"%s\"", id->filename); 1379 } 1380 } 1381 1382 /* 1383 * If the above didn't select another identity to do the signing 1384 * then default to the one we started with. 1385 */ 1386 if (sign_id == NULL) 1387 sign_id = id; 1388 1389 /* assemble and sign data */ 1390 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1391 free(alg); 1392 slen = 0; 1393 signature = NULL; 1394 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1395 id->key)) == NULL) { 1396 error_f("no mutual signature supported"); 1397 goto out; 1398 } 1399 debug3_f("signing using %s %s", alg, fp); 1400 1401 sshbuf_free(b); 1402 if ((b = sshbuf_new()) == NULL) 1403 fatal_f("sshbuf_new failed"); 1404 if (ssh->compat & SSH_OLD_SESSIONID) { 1405 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1406 fatal_fr(r, "sshbuf_putb"); 1407 } else { 1408 if ((r = sshbuf_put_stringb(b, 1409 ssh->kex->session_id)) != 0) 1410 fatal_fr(r, "sshbuf_put_stringb"); 1411 } 1412 skip = sshbuf_len(b); 1413 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1414 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1415 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1416 (r = sshbuf_put_cstring(b, method)) != 0 || 1417 (r = sshbuf_put_u8(b, 1)) != 0 || 1418 (r = sshbuf_put_cstring(b, alg)) != 0 || 1419 (r = sshkey_puts(id->key, b)) != 0) { 1420 fatal_fr(r, "assemble signed data"); 1421 } 1422 if (hostbound) { 1423 if (ssh->kex->initial_hostkey == NULL) { 1424 fatal_f("internal error: initial hostkey " 1425 "not recorded"); 1426 } 1427 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1428 fatal_fr(r, "assemble %s hostkey", method); 1429 } 1430 /* generate signature */ 1431 r = identity_sign(sign_id, &signature, &slen, 1432 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1433 if (r == 0) 1434 break; 1435 else if (r == SSH_ERR_KEY_NOT_FOUND) 1436 goto out; /* soft failure */ 1437 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1438 !fallback_sigtype) { 1439 if (sign_id->agent_fd != -1) 1440 loc = "agent "; 1441 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1442 loc = "token "; 1443 logit("%skey %s %s returned incorrect signature type", 1444 loc, sshkey_type(id->key), fp); 1445 continue; 1446 } 1447 error_fr(r, "signing failed for %s \"%s\"%s", 1448 sshkey_type(sign_id->key), sign_id->filename, 1449 id->agent_fd != -1 ? " from agent" : ""); 1450 goto out; 1451 } 1452 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1453 fatal_f("no signature"); 1454 1455 /* append signature */ 1456 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1457 fatal_fr(r, "append signature"); 1458 1459 #ifdef DEBUG_PK 1460 sshbuf_dump(b, stderr); 1461 #endif 1462 /* skip session id and packet type */ 1463 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1464 fatal_fr(r, "consume"); 1465 1466 /* put remaining data from buffer into packet */ 1467 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1468 (r = sshpkt_putb(ssh, b)) != 0 || 1469 (r = sshpkt_send(ssh)) != 0) 1470 fatal_fr(r, "enqueue request"); 1471 1472 /* success */ 1473 sent = 1; 1474 1475 out: 1476 free(fp); 1477 free(alg); 1478 sshbuf_free(b); 1479 freezero(signature, slen); 1480 return sent; 1481 } 1482 1483 static int 1484 send_pubkey_test(struct ssh *ssh, Identity *id) 1485 { 1486 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1487 u_char *blob = NULL; 1488 char *alg = NULL; 1489 size_t bloblen; 1490 u_int have_sig = 0; 1491 int sent = 0, r; 1492 1493 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1494 debug_f("no mutual signature algorithm"); 1495 goto out; 1496 } 1497 1498 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1499 /* we cannot handle this key */ 1500 debug3_f("cannot handle key"); 1501 goto out; 1502 } 1503 /* register callback for USERAUTH_PK_OK message */ 1504 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1505 1506 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1507 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1508 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1509 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1510 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1511 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1512 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1513 (r = sshpkt_send(ssh)) != 0) 1514 fatal_fr(r, "send packet"); 1515 sent = 1; 1516 1517 out: 1518 free(alg); 1519 free(blob); 1520 return sent; 1521 } 1522 1523 static struct sshkey * 1524 load_identity_file(Identity *id) 1525 { 1526 struct sshkey *private = NULL; 1527 char prompt[300], *passphrase, *comment; 1528 int r, quit = 0, i; 1529 struct stat st; 1530 1531 if (stat(id->filename, &st) == -1) { 1532 do_log2(id->userprovided ? 1533 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1534 "no such identity: %s: %s", id->filename, strerror(errno)); 1535 return NULL; 1536 } 1537 snprintf(prompt, sizeof prompt, 1538 "Enter passphrase for key '%.100s': ", id->filename); 1539 for (i = 0; i <= options.number_of_password_prompts; i++) { 1540 if (i == 0) 1541 passphrase = ""; 1542 else { 1543 passphrase = read_passphrase(prompt, 0); 1544 if (*passphrase == '\0') { 1545 debug2("no passphrase given, try next key"); 1546 free(passphrase); 1547 break; 1548 } 1549 } 1550 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1551 passphrase, &private, &comment))) { 1552 case 0: 1553 break; 1554 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1555 if (options.batch_mode) { 1556 quit = 1; 1557 break; 1558 } 1559 if (i != 0) 1560 debug2("bad passphrase given, try again..."); 1561 break; 1562 case SSH_ERR_SYSTEM_ERROR: 1563 if (errno == ENOENT) { 1564 debug2_r(r, "Load key \"%s\"", id->filename); 1565 quit = 1; 1566 break; 1567 } 1568 /* FALLTHROUGH */ 1569 default: 1570 error_r(r, "Load key \"%s\"", id->filename); 1571 quit = 1; 1572 break; 1573 } 1574 if (private != NULL && sshkey_is_sk(private) && 1575 options.sk_provider == NULL) { 1576 debug("key \"%s\" is an authenticator-hosted key, " 1577 "but no provider specified", id->filename); 1578 sshkey_free(private); 1579 private = NULL; 1580 quit = 1; 1581 } 1582 if (!quit && (r = sshkey_check_rsa_length(private, 1583 options.required_rsa_size)) != 0) { 1584 debug_fr(r, "Skipping key %s", id->filename); 1585 sshkey_free(private); 1586 private = NULL; 1587 quit = 1; 1588 } 1589 if (!quit && private != NULL && id->agent_fd == -1 && 1590 !(id->key && id->isprivate)) 1591 maybe_add_key_to_agent(id->filename, private, comment, 1592 passphrase); 1593 if (i > 0) 1594 freezero(passphrase, strlen(passphrase)); 1595 free(comment); 1596 if (private != NULL || quit) 1597 break; 1598 } 1599 return private; 1600 } 1601 1602 static int 1603 key_type_allowed_by_config(struct sshkey *key) 1604 { 1605 if (match_pattern_list(sshkey_ssh_name(key), 1606 options.pubkey_accepted_algos, 0) == 1) 1607 return 1; 1608 1609 /* RSA keys/certs might be allowed by alternate signature types */ 1610 switch (key->type) { 1611 case KEY_RSA: 1612 if (match_pattern_list("rsa-sha2-512", 1613 options.pubkey_accepted_algos, 0) == 1) 1614 return 1; 1615 if (match_pattern_list("rsa-sha2-256", 1616 options.pubkey_accepted_algos, 0) == 1) 1617 return 1; 1618 break; 1619 case KEY_RSA_CERT: 1620 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1621 options.pubkey_accepted_algos, 0) == 1) 1622 return 1; 1623 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1624 options.pubkey_accepted_algos, 0) == 1) 1625 return 1; 1626 break; 1627 } 1628 return 0; 1629 } 1630 1631 /* obtain a list of keys from the agent */ 1632 static int 1633 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1634 struct ssh_identitylist **idlistp) 1635 { 1636 int r, agent_fd; 1637 struct ssh_identitylist *idlist; 1638 1639 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1640 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1641 debug_fr(r, "ssh_get_authentication_socket"); 1642 return r; 1643 } 1644 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1645 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1646 debug_f("bound agent to hostkey"); 1647 else 1648 debug2_fr(r, "ssh_agent_bind_hostkey"); 1649 1650 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1651 debug_fr(r, "ssh_fetch_identitylist"); 1652 close(agent_fd); 1653 return r; 1654 } 1655 /* success */ 1656 *agent_fdp = agent_fd; 1657 *idlistp = idlist; 1658 debug_f("agent returned %zu keys", idlist->nkeys); 1659 return 0; 1660 } 1661 1662 /* 1663 * try keys in the following order: 1664 * 1. certificates listed in the config file 1665 * 2. other input certificates 1666 * 3. agent keys that are found in the config file 1667 * 4. other agent keys 1668 * 5. keys that are only listed in the config file 1669 */ 1670 static void 1671 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1672 { 1673 struct identity *id, *id2, *tmp; 1674 struct idlist agent, files, *preferred; 1675 struct sshkey *key; 1676 int agent_fd = -1, i, r, found; 1677 size_t j; 1678 struct ssh_identitylist *idlist; 1679 char *ident; 1680 1681 TAILQ_INIT(&agent); /* keys from the agent */ 1682 TAILQ_INIT(&files); /* keys from the config file */ 1683 preferred = &authctxt->keys; 1684 TAILQ_INIT(preferred); /* preferred order of keys */ 1685 1686 /* list of keys stored in the filesystem and PKCS#11 */ 1687 for (i = 0; i < options.num_identity_files; i++) { 1688 key = options.identity_keys[i]; 1689 if (key && key->cert && 1690 key->cert->type != SSH2_CERT_TYPE_USER) { 1691 debug_f("ignoring certificate %s: not a user " 1692 "certificate", options.identity_files[i]); 1693 continue; 1694 } 1695 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1696 debug_f("ignoring authenticator-hosted key %s as no " 1697 "SecurityKeyProvider has been specified", 1698 options.identity_files[i]); 1699 continue; 1700 } 1701 options.identity_keys[i] = NULL; 1702 id = xcalloc(1, sizeof(*id)); 1703 id->agent_fd = -1; 1704 id->key = key; 1705 id->filename = xstrdup(options.identity_files[i]); 1706 id->userprovided = options.identity_file_userprovided[i]; 1707 TAILQ_INSERT_TAIL(&files, id, next); 1708 } 1709 /* list of certificates specified by user */ 1710 for (i = 0; i < options.num_certificate_files; i++) { 1711 key = options.certificates[i]; 1712 if (!sshkey_is_cert(key) || key->cert == NULL || 1713 key->cert->type != SSH2_CERT_TYPE_USER) { 1714 debug_f("ignoring certificate %s: not a user " 1715 "certificate", options.identity_files[i]); 1716 continue; 1717 } 1718 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1719 debug_f("ignoring authenticator-hosted key " 1720 "certificate %s as no " 1721 "SecurityKeyProvider has been specified", 1722 options.identity_files[i]); 1723 continue; 1724 } 1725 id = xcalloc(1, sizeof(*id)); 1726 id->agent_fd = -1; 1727 id->key = key; 1728 id->filename = xstrdup(options.certificate_files[i]); 1729 id->userprovided = options.certificate_file_userprovided[i]; 1730 TAILQ_INSERT_TAIL(preferred, id, next); 1731 } 1732 /* list of keys supported by the agent */ 1733 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1734 for (j = 0; j < idlist->nkeys; j++) { 1735 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1736 options.required_rsa_size)) != 0) { 1737 debug_fr(r, "ignoring %s agent key", 1738 sshkey_ssh_name(idlist->keys[j])); 1739 continue; 1740 } 1741 found = 0; 1742 TAILQ_FOREACH(id, &files, next) { 1743 /* 1744 * agent keys from the config file are 1745 * preferred 1746 */ 1747 if (sshkey_equal(idlist->keys[j], id->key)) { 1748 TAILQ_REMOVE(&files, id, next); 1749 TAILQ_INSERT_TAIL(preferred, id, next); 1750 id->agent_fd = agent_fd; 1751 found = 1; 1752 break; 1753 } 1754 } 1755 if (!found && !options.identities_only) { 1756 id = xcalloc(1, sizeof(*id)); 1757 /* XXX "steals" key/comment from idlist */ 1758 id->key = idlist->keys[j]; 1759 id->filename = idlist->comments[j]; 1760 idlist->keys[j] = NULL; 1761 idlist->comments[j] = NULL; 1762 id->agent_fd = agent_fd; 1763 TAILQ_INSERT_TAIL(&agent, id, next); 1764 } 1765 } 1766 ssh_free_identitylist(idlist); 1767 /* append remaining agent keys */ 1768 TAILQ_CONCAT(preferred, &agent, next); 1769 authctxt->agent_fd = agent_fd; 1770 } 1771 /* Prefer PKCS11 keys that are explicitly listed */ 1772 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1773 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1774 continue; 1775 found = 0; 1776 TAILQ_FOREACH(id2, &files, next) { 1777 if (id2->key == NULL || 1778 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1779 continue; 1780 if (sshkey_equal(id->key, id2->key)) { 1781 TAILQ_REMOVE(&files, id, next); 1782 TAILQ_INSERT_TAIL(preferred, id, next); 1783 found = 1; 1784 break; 1785 } 1786 } 1787 /* If IdentitiesOnly set and key not found then don't use it */ 1788 if (!found && options.identities_only) { 1789 TAILQ_REMOVE(&files, id, next); 1790 freezero(id, sizeof(*id)); 1791 } 1792 } 1793 /* append remaining keys from the config file */ 1794 TAILQ_CONCAT(preferred, &files, next); 1795 /* finally, filter by PubkeyAcceptedAlgorithms */ 1796 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1797 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1798 debug("Skipping %s key %s - " 1799 "corresponding algo not in PubkeyAcceptedAlgorithms", 1800 sshkey_ssh_name(id->key), id->filename); 1801 TAILQ_REMOVE(preferred, id, next); 1802 sshkey_free(id->key); 1803 free(id->filename); 1804 memset(id, 0, sizeof(*id)); 1805 continue; 1806 } 1807 } 1808 /* List the keys we plan on using */ 1809 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1810 ident = format_identity(id); 1811 debug("Will attempt key: %s", ident); 1812 free(ident); 1813 } 1814 debug2_f("done"); 1815 } 1816 1817 static void 1818 pubkey_cleanup(struct ssh *ssh) 1819 { 1820 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1821 Identity *id; 1822 1823 if (authctxt->agent_fd != -1) { 1824 ssh_close_authentication_socket(authctxt->agent_fd); 1825 authctxt->agent_fd = -1; 1826 } 1827 for (id = TAILQ_FIRST(&authctxt->keys); id; 1828 id = TAILQ_FIRST(&authctxt->keys)) { 1829 TAILQ_REMOVE(&authctxt->keys, id, next); 1830 sshkey_free(id->key); 1831 free(id->filename); 1832 free(id); 1833 } 1834 } 1835 1836 static void 1837 pubkey_reset(Authctxt *authctxt) 1838 { 1839 Identity *id; 1840 1841 TAILQ_FOREACH(id, &authctxt->keys, next) 1842 id->tried = 0; 1843 } 1844 1845 static int 1846 userauth_pubkey(struct ssh *ssh) 1847 { 1848 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1849 Identity *id; 1850 int sent = 0; 1851 char *ident; 1852 1853 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1854 if (id->tried++) 1855 return (0); 1856 /* move key to the end of the queue */ 1857 TAILQ_REMOVE(&authctxt->keys, id, next); 1858 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1859 /* 1860 * send a test message if we have the public key. for 1861 * encrypted keys we cannot do this and have to load the 1862 * private key instead 1863 */ 1864 if (id->key != NULL) { 1865 ident = format_identity(id); 1866 debug("Offering public key: %s", ident); 1867 free(ident); 1868 sent = send_pubkey_test(ssh, id); 1869 } else { 1870 debug("Trying private key: %s", id->filename); 1871 id->key = load_identity_file(id); 1872 if (id->key != NULL) { 1873 if (id->key != NULL) { 1874 id->isprivate = 1; 1875 sent = sign_and_send_pubkey(ssh, id); 1876 } 1877 sshkey_free(id->key); 1878 id->key = NULL; 1879 id->isprivate = 0; 1880 } 1881 } 1882 if (sent) 1883 return (sent); 1884 } 1885 return (0); 1886 } 1887 1888 /* 1889 * Send userauth request message specifying keyboard-interactive method. 1890 */ 1891 static int 1892 userauth_kbdint(struct ssh *ssh) 1893 { 1894 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1895 int r; 1896 1897 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1898 return 0; 1899 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1900 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1901 debug3("userauth_kbdint: disable: no info_req_seen"); 1902 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1903 return 0; 1904 } 1905 1906 debug2("userauth_kbdint"); 1907 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1908 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1909 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1910 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1911 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1912 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1913 options.kbd_interactive_devices : "")) != 0 || 1914 (r = sshpkt_send(ssh)) != 0) 1915 fatal_fr(r, "send packet"); 1916 1917 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1918 return 1; 1919 } 1920 1921 /* 1922 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1923 */ 1924 static int 1925 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1926 { 1927 Authctxt *authctxt = ssh->authctxt; 1928 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1929 char *display_prompt = NULL, *response = NULL; 1930 u_char echo = 0; 1931 u_int num_prompts, i; 1932 int r; 1933 1934 debug2_f("entering"); 1935 1936 if (authctxt == NULL) 1937 fatal_f("no authentication context"); 1938 1939 authctxt->info_req_seen = 1; 1940 1941 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1942 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1943 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1944 goto out; 1945 if (strlen(name) > 0) 1946 logit("%s", name); 1947 if (strlen(inst) > 0) 1948 logit("%s", inst); 1949 1950 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1951 goto out; 1952 /* 1953 * Begin to build info response packet based on prompts requested. 1954 * We commit to providing the correct number of responses, so if 1955 * further on we run into a problem that prevents this, we have to 1956 * be sure and clean this up and send a correct error response. 1957 */ 1958 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1959 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1960 goto out; 1961 1962 debug2_f("num_prompts %d", num_prompts); 1963 for (i = 0; i < num_prompts; i++) { 1964 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1965 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1966 goto out; 1967 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1968 authctxt->server_user, options.host_key_alias ? 1969 options.host_key_alias : authctxt->host, prompt) == -1) 1970 fatal_f("asmprintf failed"); 1971 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1972 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1973 goto out; 1974 freezero(response, strlen(response)); 1975 free(prompt); 1976 free(display_prompt); 1977 display_prompt = response = prompt = NULL; 1978 } 1979 /* done with parsing incoming message. */ 1980 if ((r = sshpkt_get_end(ssh)) != 0 || 1981 (r = sshpkt_add_padding(ssh, 64)) != 0) 1982 goto out; 1983 r = sshpkt_send(ssh); 1984 out: 1985 if (response) 1986 freezero(response, strlen(response)); 1987 free(prompt); 1988 free(display_prompt); 1989 free(name); 1990 free(inst); 1991 free(lang); 1992 return r; 1993 } 1994 1995 static int 1996 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1997 const u_char *data, size_t datalen) 1998 { 1999 struct sshbuf *b; 2000 struct stat st; 2001 pid_t pid; 2002 int r, to[2], from[2], status; 2003 int sock = ssh_packet_get_connection_in(ssh); 2004 u_char rversion = 0, version = 2; 2005 void (*osigchld)(int); 2006 2007 *sigp = NULL; 2008 *lenp = 0; 2009 2010 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2011 error_f("not installed: %s", strerror(errno)); 2012 return -1; 2013 } 2014 if (fflush(stdout) != 0) { 2015 error_f("fflush: %s", strerror(errno)); 2016 return -1; 2017 } 2018 if (pipe(to) == -1) { 2019 error_f("pipe: %s", strerror(errno)); 2020 return -1; 2021 } 2022 if (pipe(from) == -1) { 2023 error_f("pipe: %s", strerror(errno)); 2024 return -1; 2025 } 2026 if ((pid = fork()) == -1) { 2027 error_f("fork: %s", strerror(errno)); 2028 return -1; 2029 } 2030 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2031 if (pid == 0) { 2032 close(from[0]); 2033 if (dup2(from[1], STDOUT_FILENO) == -1) 2034 fatal_f("dup2: %s", strerror(errno)); 2035 close(to[1]); 2036 if (dup2(to[0], STDIN_FILENO) == -1) 2037 fatal_f("dup2: %s", strerror(errno)); 2038 close(from[1]); 2039 close(to[0]); 2040 2041 if (dup2(sock, STDERR_FILENO + 1) == -1) 2042 fatal_f("dup2: %s", strerror(errno)); 2043 sock = STDERR_FILENO + 1; 2044 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2045 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2046 closefrom(sock + 1); 2047 2048 debug3_f("[child] pid=%ld, exec %s", 2049 (long)getpid(), _PATH_SSH_KEY_SIGN); 2050 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2051 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2052 strerror(errno)); 2053 } 2054 close(from[1]); 2055 close(to[0]); 2056 sock = STDERR_FILENO + 1; 2057 2058 if ((b = sshbuf_new()) == NULL) 2059 fatal_f("sshbuf_new failed"); 2060 /* send # of sock, data to be signed */ 2061 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2062 (r = sshbuf_put_string(b, data, datalen)) != 0) 2063 fatal_fr(r, "buffer error"); 2064 if (ssh_msg_send(to[1], version, b) == -1) 2065 fatal_f("couldn't send request"); 2066 sshbuf_reset(b); 2067 r = ssh_msg_recv(from[0], b); 2068 close(from[0]); 2069 close(to[1]); 2070 if (r < 0) { 2071 error_f("no reply"); 2072 goto fail; 2073 } 2074 2075 errno = 0; 2076 while (waitpid(pid, &status, 0) == -1) { 2077 if (errno != EINTR) { 2078 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2079 goto fail; 2080 } 2081 } 2082 if (!WIFEXITED(status)) { 2083 error_f("exited abnormally"); 2084 goto fail; 2085 } 2086 if (WEXITSTATUS(status) != 0) { 2087 error_f("exited with status %d", WEXITSTATUS(status)); 2088 goto fail; 2089 } 2090 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2091 error_fr(r, "buffer error"); 2092 goto fail; 2093 } 2094 if (rversion != version) { 2095 error_f("bad version"); 2096 goto fail; 2097 } 2098 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2099 error_fr(r, "buffer error"); 2100 fail: 2101 ssh_signal(SIGCHLD, osigchld); 2102 sshbuf_free(b); 2103 return -1; 2104 } 2105 ssh_signal(SIGCHLD, osigchld); 2106 sshbuf_free(b); 2107 2108 return 0; 2109 } 2110 2111 static int 2112 userauth_hostbased(struct ssh *ssh) 2113 { 2114 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2115 struct sshkey *private = NULL; 2116 struct sshbuf *b = NULL; 2117 u_char *sig = NULL, *keyblob = NULL; 2118 char *fp = NULL, *chost = NULL, *lname = NULL; 2119 size_t siglen = 0, keylen = 0; 2120 int i, r, success = 0; 2121 2122 if (authctxt->ktypes == NULL) { 2123 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2124 authctxt->ktypes = authctxt->oktypes; 2125 } 2126 2127 /* 2128 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2129 * trying each hostkey that matches the type in turn. 2130 */ 2131 for (;;) { 2132 if (authctxt->active_ktype == NULL) 2133 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2134 if (authctxt->active_ktype == NULL || 2135 *authctxt->active_ktype == '\0') 2136 break; 2137 debug3_f("trying key type %s", authctxt->active_ktype); 2138 2139 /* check for a useful key */ 2140 private = NULL; 2141 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2142 if (authctxt->sensitive->keys[i] == NULL || 2143 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2144 continue; 2145 if (!sshkey_match_keyname_to_sigalgs( 2146 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2147 authctxt->active_ktype)) 2148 continue; 2149 /* we take and free the key */ 2150 private = authctxt->sensitive->keys[i]; 2151 authctxt->sensitive->keys[i] = NULL; 2152 break; 2153 } 2154 /* Found one */ 2155 if (private != NULL) 2156 break; 2157 /* No more keys of this type; advance */ 2158 authctxt->active_ktype = NULL; 2159 } 2160 if (private == NULL) { 2161 free(authctxt->oktypes); 2162 authctxt->oktypes = authctxt->ktypes = NULL; 2163 authctxt->active_ktype = NULL; 2164 debug("No more client hostkeys for hostbased authentication."); 2165 goto out; 2166 } 2167 2168 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2169 SSH_FP_DEFAULT)) == NULL) { 2170 error_f("sshkey_fingerprint failed"); 2171 goto out; 2172 } 2173 debug_f("trying hostkey %s %s using sigalg %s", 2174 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2175 2176 /* figure out a name for the client host */ 2177 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2178 if (lname == NULL) { 2179 error_f("cannot get local ipaddr/name"); 2180 goto out; 2181 } 2182 2183 /* XXX sshbuf_put_stringf? */ 2184 xasprintf(&chost, "%s.", lname); 2185 debug2_f("chost %s", chost); 2186 2187 /* construct data */ 2188 if ((b = sshbuf_new()) == NULL) { 2189 error_f("sshbuf_new failed"); 2190 goto out; 2191 } 2192 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2193 error_fr(r, "sshkey_to_blob"); 2194 goto out; 2195 } 2196 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2197 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2198 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2199 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2200 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2201 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2202 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2203 (r = sshbuf_put_cstring(b, chost)) != 0 || 2204 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2205 error_fr(r, "buffer error"); 2206 goto out; 2207 } 2208 2209 #ifdef DEBUG_PK 2210 sshbuf_dump(b, stderr); 2211 #endif 2212 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2213 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2214 error("sign using hostkey %s %s failed", 2215 sshkey_ssh_name(private), fp); 2216 goto out; 2217 } 2218 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2219 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2220 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2221 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2222 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2223 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2224 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2225 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2226 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2227 (r = sshpkt_send(ssh)) != 0) { 2228 error_fr(r, "packet error"); 2229 goto out; 2230 } 2231 success = 1; 2232 2233 out: 2234 if (sig != NULL) 2235 freezero(sig, siglen); 2236 free(keyblob); 2237 free(lname); 2238 free(fp); 2239 free(chost); 2240 sshkey_free(private); 2241 sshbuf_free(b); 2242 2243 return success; 2244 } 2245 2246 /* find auth method */ 2247 2248 /* 2249 * given auth method name, if configurable options permit this method fill 2250 * in auth_ident field and return true, otherwise return false. 2251 */ 2252 static int 2253 authmethod_is_enabled(Authmethod *method) 2254 { 2255 if (method == NULL) 2256 return 0; 2257 /* return false if options indicate this method is disabled */ 2258 if (method->enabled == NULL || *method->enabled == 0) 2259 return 0; 2260 /* return false if batch mode is enabled but method needs interactive mode */ 2261 if (method->batch_flag != NULL && *method->batch_flag != 0) 2262 return 0; 2263 return 1; 2264 } 2265 2266 static Authmethod * 2267 authmethod_lookup(const char *name) 2268 { 2269 Authmethod *method = NULL; 2270 if (name != NULL) 2271 for (method = authmethods; method->name != NULL; method++) 2272 if (strcmp(name, method->name) == 0) 2273 return method; 2274 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2275 return NULL; 2276 } 2277 2278 /* XXX internal state */ 2279 static Authmethod *current = NULL; 2280 static char *supported = NULL; 2281 static char *preferred = NULL; 2282 2283 /* 2284 * Given the authentication method list sent by the server, return the 2285 * next method we should try. If the server initially sends a nil list, 2286 * use a built-in default list. 2287 */ 2288 static Authmethod * 2289 authmethod_get(char *authlist) 2290 { 2291 char *name = NULL; 2292 u_int next; 2293 2294 /* Use a suitable default if we're passed a nil list. */ 2295 if (authlist == NULL || strlen(authlist) == 0) 2296 authlist = options.preferred_authentications; 2297 2298 if (supported == NULL || strcmp(authlist, supported) != 0) { 2299 debug3("start over, passed a different list %s", authlist); 2300 free(supported); 2301 supported = xstrdup(authlist); 2302 preferred = options.preferred_authentications; 2303 debug3("preferred %s", preferred); 2304 current = NULL; 2305 } else if (current != NULL && authmethod_is_enabled(current)) 2306 return current; 2307 2308 for (;;) { 2309 if ((name = match_list(preferred, supported, &next)) == NULL) { 2310 debug("No more authentication methods to try."); 2311 current = NULL; 2312 return NULL; 2313 } 2314 preferred += next; 2315 debug3("authmethod_lookup %s", name); 2316 debug3("remaining preferred: %s", preferred); 2317 if ((current = authmethod_lookup(name)) != NULL && 2318 authmethod_is_enabled(current)) { 2319 debug3("authmethod_is_enabled %s", name); 2320 debug("Next authentication method: %s", name); 2321 free(name); 2322 return current; 2323 } 2324 free(name); 2325 } 2326 } 2327 2328 static char * 2329 authmethods_get(void) 2330 { 2331 Authmethod *method = NULL; 2332 struct sshbuf *b; 2333 char *list; 2334 int r; 2335 2336 if ((b = sshbuf_new()) == NULL) 2337 fatal_f("sshbuf_new failed"); 2338 for (method = authmethods; method->name != NULL; method++) { 2339 if (authmethod_is_enabled(method)) { 2340 if ((r = sshbuf_putf(b, "%s%s", 2341 sshbuf_len(b) ? "," : "", method->name)) != 0) 2342 fatal_fr(r, "buffer error"); 2343 } 2344 } 2345 if ((list = sshbuf_dup_string(b)) == NULL) 2346 fatal_f("sshbuf_dup_string failed"); 2347 sshbuf_free(b); 2348 return list; 2349 } 2350