1 /* $OpenBSD: sshconnect2.c,v 1.366 2023/03/09 07:11:05 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_ext_info(int, u_int32_t, struct ssh *); 362 static int input_userauth_success(int, u_int32_t, struct ssh *); 363 static int input_userauth_failure(int, u_int32_t, struct ssh *); 364 static int input_userauth_banner(int, u_int32_t, struct ssh *); 365 static int input_userauth_error(int, u_int32_t, struct ssh *); 366 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 367 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 368 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 369 370 static int userauth_none(struct ssh *); 371 static int userauth_pubkey(struct ssh *); 372 static int userauth_passwd(struct ssh *); 373 static int userauth_kbdint(struct ssh *); 374 static int userauth_hostbased(struct ssh *); 375 376 #ifdef GSSAPI 377 static int userauth_gssapi(struct ssh *); 378 static void userauth_gssapi_cleanup(struct ssh *); 379 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 380 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 381 static int input_gssapi_error(int, u_int32_t, struct ssh *); 382 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 383 #endif 384 385 void userauth(struct ssh *, char *); 386 387 static void pubkey_cleanup(struct ssh *); 388 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 389 static void pubkey_prepare(struct ssh *, Authctxt *); 390 static void pubkey_reset(Authctxt *); 391 static struct sshkey *load_identity_file(Identity *); 392 393 static Authmethod *authmethod_get(char *authlist); 394 static Authmethod *authmethod_lookup(const char *name); 395 static char *authmethods_get(void); 396 397 Authmethod authmethods[] = { 398 #ifdef GSSAPI 399 {"gssapi-with-mic", 400 userauth_gssapi, 401 userauth_gssapi_cleanup, 402 &options.gss_authentication, 403 NULL}, 404 #endif 405 {"hostbased", 406 userauth_hostbased, 407 NULL, 408 &options.hostbased_authentication, 409 NULL}, 410 {"publickey", 411 userauth_pubkey, 412 NULL, 413 &options.pubkey_authentication, 414 NULL}, 415 {"keyboard-interactive", 416 userauth_kbdint, 417 NULL, 418 &options.kbd_interactive_authentication, 419 &options.batch_mode}, 420 {"password", 421 userauth_passwd, 422 NULL, 423 &options.password_authentication, 424 &options.batch_mode}, 425 {"none", 426 userauth_none, 427 NULL, 428 NULL, 429 NULL}, 430 {NULL, NULL, NULL, NULL, NULL} 431 }; 432 433 void 434 ssh_userauth2(struct ssh *ssh, const char *local_user, 435 const char *server_user, char *host, Sensitive *sensitive) 436 { 437 Authctxt authctxt; 438 int r; 439 440 if (options.preferred_authentications == NULL) 441 options.preferred_authentications = authmethods_get(); 442 443 /* setup authentication context */ 444 memset(&authctxt, 0, sizeof(authctxt)); 445 authctxt.server_user = server_user; 446 authctxt.local_user = local_user; 447 authctxt.host = host; 448 authctxt.service = "ssh-connection"; /* service name */ 449 authctxt.success = 0; 450 authctxt.method = authmethod_lookup("none"); 451 authctxt.authlist = NULL; 452 authctxt.methoddata = NULL; 453 authctxt.sensitive = sensitive; 454 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 455 authctxt.info_req_seen = 0; 456 authctxt.attempt_kbdint = 0; 457 authctxt.attempt_passwd = 0; 458 #if GSSAPI 459 authctxt.gss_supported_mechs = NULL; 460 authctxt.mech_tried = 0; 461 #endif 462 authctxt.agent_fd = -1; 463 pubkey_prepare(ssh, &authctxt); 464 if (authctxt.method == NULL) { 465 fatal_f("internal error: cannot send userauth none request"); 466 } 467 468 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 469 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 470 (r = sshpkt_send(ssh)) != 0) 471 fatal_fr(r, "send packet"); 472 473 ssh->authctxt = &authctxt; 474 ssh_dispatch_init(ssh, &input_userauth_error); 475 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 476 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 477 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 478 pubkey_cleanup(ssh); 479 ssh->authctxt = NULL; 480 481 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 482 483 if (!authctxt.success) 484 fatal("Authentication failed."); 485 if (ssh_packet_connection_is_on_socket(ssh)) { 486 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 487 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 488 authctxt.method->name); 489 } else { 490 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 491 authctxt.method->name); 492 } 493 } 494 495 static int 496 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 497 { 498 int r; 499 500 if (ssh_packet_remaining(ssh) > 0) { 501 char *reply; 502 503 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 504 goto out; 505 debug2("service_accept: %s", reply); 506 free(reply); 507 } else { 508 debug2("buggy server: service_accept w/o service"); 509 } 510 if ((r = sshpkt_get_end(ssh)) != 0) 511 goto out; 512 debug("SSH2_MSG_SERVICE_ACCEPT received"); 513 514 /* initial userauth request */ 515 userauth_none(ssh); 516 517 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 519 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 520 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 521 r = 0; 522 out: 523 return r; 524 } 525 526 static int 527 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 528 { 529 return kex_input_ext_info(type, seqnr, ssh); 530 } 531 532 void 533 userauth(struct ssh *ssh, char *authlist) 534 { 535 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 536 537 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 538 authctxt->method->cleanup(ssh); 539 540 free(authctxt->methoddata); 541 authctxt->methoddata = NULL; 542 if (authlist == NULL) { 543 authlist = authctxt->authlist; 544 } else { 545 free(authctxt->authlist); 546 authctxt->authlist = authlist; 547 } 548 for (;;) { 549 Authmethod *method = authmethod_get(authlist); 550 if (method == NULL) 551 fatal("%s@%s: Permission denied (%s).", 552 authctxt->server_user, authctxt->host, authlist); 553 authctxt->method = method; 554 555 /* reset the per method handler */ 556 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 557 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 558 559 /* and try new method */ 560 if (method->userauth(ssh) != 0) { 561 debug2("we sent a %s packet, wait for reply", method->name); 562 break; 563 } else { 564 debug2("we did not send a packet, disable method"); 565 method->enabled = NULL; 566 } 567 } 568 } 569 570 static int 571 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 572 { 573 fatal_f("bad message during authentication: type %d", type); 574 return 0; 575 } 576 577 static int 578 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 579 { 580 char *msg = NULL; 581 size_t len; 582 int r; 583 584 debug3_f("entering"); 585 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 586 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 587 goto out; 588 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 589 fmprintf(stderr, "%s", msg); 590 r = 0; 591 out: 592 free(msg); 593 return r; 594 } 595 596 static int 597 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 598 { 599 Authctxt *authctxt = ssh->authctxt; 600 601 if (authctxt == NULL) 602 fatal_f("no authentication context"); 603 free(authctxt->authlist); 604 authctxt->authlist = NULL; 605 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 606 authctxt->method->cleanup(ssh); 607 free(authctxt->methoddata); 608 authctxt->methoddata = NULL; 609 authctxt->success = 1; /* break out */ 610 return 0; 611 } 612 613 #if 0 614 static int 615 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 616 { 617 Authctxt *authctxt = ssh->authctxt; 618 619 if (authctxt == NULL) 620 fatal_f("no authentication context"); 621 622 fatal("Unexpected authentication success during %s.", 623 authctxt->method->name); 624 return 0; 625 } 626 #endif 627 628 static int 629 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 630 { 631 Authctxt *authctxt = ssh->authctxt; 632 char *authlist = NULL; 633 u_char partial; 634 635 if (authctxt == NULL) 636 fatal("input_userauth_failure: no authentication context"); 637 638 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 639 sshpkt_get_u8(ssh, &partial) != 0 || 640 sshpkt_get_end(ssh) != 0) 641 goto out; 642 643 if (partial != 0) { 644 verbose("Authenticated using \"%s\" with partial success.", 645 authctxt->method->name); 646 /* reset state */ 647 pubkey_reset(authctxt); 648 } 649 debug("Authentications that can continue: %s", authlist); 650 651 userauth(ssh, authlist); 652 authlist = NULL; 653 out: 654 free(authlist); 655 return 0; 656 } 657 658 /* 659 * Format an identity for logging including filename, key type, fingerprint 660 * and location (agent, etc.). Caller must free. 661 */ 662 static char * 663 format_identity(Identity *id) 664 { 665 char *fp = NULL, *ret = NULL; 666 const char *note = ""; 667 668 if (id->key != NULL) { 669 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 670 SSH_FP_DEFAULT); 671 } 672 if (id->key) { 673 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 674 note = " token"; 675 else if (sshkey_is_sk(id->key)) 676 note = " authenticator"; 677 } 678 xasprintf(&ret, "%s %s%s%s%s%s%s", 679 id->filename, 680 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 681 fp ? fp : "", 682 id->userprovided ? " explicit" : "", note, 683 id->agent_fd != -1 ? " agent" : ""); 684 free(fp); 685 return ret; 686 } 687 688 static int 689 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 690 { 691 Authctxt *authctxt = ssh->authctxt; 692 struct sshkey *key = NULL; 693 Identity *id = NULL; 694 int pktype, found = 0, sent = 0; 695 size_t blen; 696 char *pkalg = NULL, *fp = NULL, *ident = NULL; 697 u_char *pkblob = NULL; 698 int r; 699 700 if (authctxt == NULL) 701 fatal("input_userauth_pk_ok: no authentication context"); 702 703 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 704 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 705 (r = sshpkt_get_end(ssh)) != 0) 706 goto done; 707 708 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 709 debug_f("server sent unknown pkalg %s", pkalg); 710 goto done; 711 } 712 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 713 debug_r(r, "no key from blob. pkalg %s", pkalg); 714 goto done; 715 } 716 if (key->type != pktype) { 717 error("input_userauth_pk_ok: type mismatch " 718 "for decoded key (received %d, expected %d)", 719 key->type, pktype); 720 goto done; 721 } 722 723 /* 724 * search keys in the reverse order, because last candidate has been 725 * moved to the end of the queue. this also avoids confusion by 726 * duplicate keys 727 */ 728 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 729 if (sshkey_equal(key, id->key)) { 730 found = 1; 731 break; 732 } 733 } 734 if (!found || id == NULL) { 735 fp = sshkey_fingerprint(key, options.fingerprint_hash, 736 SSH_FP_DEFAULT); 737 error_f("server replied with unknown key: %s %s", 738 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 739 goto done; 740 } 741 ident = format_identity(id); 742 debug("Server accepts key: %s", ident); 743 sent = sign_and_send_pubkey(ssh, id); 744 r = 0; 745 done: 746 sshkey_free(key); 747 free(ident); 748 free(fp); 749 free(pkalg); 750 free(pkblob); 751 752 /* try another method if we did not send a packet */ 753 if (r == 0 && sent == 0) 754 userauth(ssh, NULL); 755 return r; 756 } 757 758 #ifdef GSSAPI 759 static int 760 userauth_gssapi(struct ssh *ssh) 761 { 762 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 763 Gssctxt *gssctxt = NULL; 764 OM_uint32 min; 765 int r, ok = 0; 766 gss_OID mech = NULL; 767 768 /* Try one GSSAPI method at a time, rather than sending them all at 769 * once. */ 770 771 if (authctxt->gss_supported_mechs == NULL) 772 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 773 774 /* Check to see whether the mechanism is usable before we offer it */ 775 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 776 !ok) { 777 mech = &authctxt->gss_supported_mechs-> 778 elements[authctxt->mech_tried]; 779 /* My DER encoding requires length<128 */ 780 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 781 mech, authctxt->host)) { 782 ok = 1; /* Mechanism works */ 783 } else { 784 authctxt->mech_tried++; 785 } 786 } 787 788 if (!ok || mech == NULL) 789 return 0; 790 791 authctxt->methoddata=(void *)gssctxt; 792 793 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 794 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 795 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 796 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 797 (r = sshpkt_put_u32(ssh, 1)) != 0 || 798 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 799 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 800 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 801 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 802 (r = sshpkt_send(ssh)) != 0) 803 fatal_fr(r, "send packet"); 804 805 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 806 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 807 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 808 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 809 810 authctxt->mech_tried++; /* Move along to next candidate */ 811 812 return 1; 813 } 814 815 static void 816 userauth_gssapi_cleanup(struct ssh *ssh) 817 { 818 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 819 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 820 821 ssh_gssapi_delete_ctx(&gssctxt); 822 authctxt->methoddata = NULL; 823 824 free(authctxt->gss_supported_mechs); 825 authctxt->gss_supported_mechs = NULL; 826 } 827 828 static OM_uint32 829 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 830 { 831 Authctxt *authctxt = ssh->authctxt; 832 Gssctxt *gssctxt = authctxt->methoddata; 833 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 834 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 835 gss_buffer_desc gssbuf; 836 OM_uint32 status, ms, flags; 837 int r; 838 839 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 840 recv_tok, &send_tok, &flags); 841 842 if (send_tok.length > 0) { 843 u_char type = GSS_ERROR(status) ? 844 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 845 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 846 847 if ((r = sshpkt_start(ssh, type)) != 0 || 848 (r = sshpkt_put_string(ssh, send_tok.value, 849 send_tok.length)) != 0 || 850 (r = sshpkt_send(ssh)) != 0) 851 fatal_fr(r, "send %u packet", type); 852 853 gss_release_buffer(&ms, &send_tok); 854 } 855 856 if (status == GSS_S_COMPLETE) { 857 /* send either complete or MIC, depending on mechanism */ 858 if (!(flags & GSS_C_INTEG_FLAG)) { 859 if ((r = sshpkt_start(ssh, 860 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 861 (r = sshpkt_send(ssh)) != 0) 862 fatal_fr(r, "send completion"); 863 } else { 864 struct sshbuf *b; 865 866 if ((b = sshbuf_new()) == NULL) 867 fatal_f("sshbuf_new failed"); 868 ssh_gssapi_buildmic(b, authctxt->server_user, 869 authctxt->service, "gssapi-with-mic", 870 ssh->kex->session_id); 871 872 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 873 fatal_f("sshbuf_mutable_ptr failed"); 874 gssbuf.length = sshbuf_len(b); 875 876 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 877 878 if (!GSS_ERROR(status)) { 879 if ((r = sshpkt_start(ssh, 880 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 881 (r = sshpkt_put_string(ssh, mic.value, 882 mic.length)) != 0 || 883 (r = sshpkt_send(ssh)) != 0) 884 fatal_fr(r, "send MIC"); 885 } 886 887 sshbuf_free(b); 888 gss_release_buffer(&ms, &mic); 889 } 890 } 891 892 return status; 893 } 894 895 static int 896 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 897 { 898 Authctxt *authctxt = ssh->authctxt; 899 Gssctxt *gssctxt; 900 size_t oidlen; 901 u_char *oidv = NULL; 902 int r; 903 904 if (authctxt == NULL) 905 fatal("input_gssapi_response: no authentication context"); 906 gssctxt = authctxt->methoddata; 907 908 /* Setup our OID */ 909 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 910 goto done; 911 912 if (oidlen <= 2 || 913 oidv[0] != SSH_GSS_OIDTYPE || 914 oidv[1] != oidlen - 2) { 915 debug("Badly encoded mechanism OID received"); 916 userauth(ssh, NULL); 917 goto ok; 918 } 919 920 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 921 fatal("Server returned different OID than expected"); 922 923 if ((r = sshpkt_get_end(ssh)) != 0) 924 goto done; 925 926 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 927 /* Start again with next method on list */ 928 debug("Trying to start again"); 929 userauth(ssh, NULL); 930 goto ok; 931 } 932 ok: 933 r = 0; 934 done: 935 free(oidv); 936 return r; 937 } 938 939 static int 940 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 941 { 942 Authctxt *authctxt = ssh->authctxt; 943 gss_buffer_desc recv_tok; 944 u_char *p = NULL; 945 size_t len; 946 OM_uint32 status; 947 int r; 948 949 if (authctxt == NULL) 950 fatal("input_gssapi_response: no authentication context"); 951 952 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 953 (r = sshpkt_get_end(ssh)) != 0) 954 goto out; 955 956 recv_tok.value = p; 957 recv_tok.length = len; 958 status = process_gssapi_token(ssh, &recv_tok); 959 960 /* Start again with the next method in the list */ 961 if (GSS_ERROR(status)) { 962 userauth(ssh, NULL); 963 /* ok */ 964 } 965 r = 0; 966 out: 967 free(p); 968 return r; 969 } 970 971 static int 972 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 973 { 974 Authctxt *authctxt = ssh->authctxt; 975 Gssctxt *gssctxt; 976 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 977 gss_buffer_desc recv_tok; 978 OM_uint32 ms; 979 u_char *p = NULL; 980 size_t len; 981 int r; 982 983 if (authctxt == NULL) 984 fatal("input_gssapi_response: no authentication context"); 985 gssctxt = authctxt->methoddata; 986 987 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 988 (r = sshpkt_get_end(ssh)) != 0) { 989 free(p); 990 return r; 991 } 992 993 /* Stick it into GSSAPI and see what it says */ 994 recv_tok.value = p; 995 recv_tok.length = len; 996 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 997 &recv_tok, &send_tok, NULL); 998 free(p); 999 gss_release_buffer(&ms, &send_tok); 1000 1001 /* Server will be returning a failed packet after this one */ 1002 return 0; 1003 } 1004 1005 static int 1006 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1007 { 1008 char *msg = NULL; 1009 char *lang = NULL; 1010 int r; 1011 1012 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1013 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1014 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1015 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1016 goto out; 1017 r = sshpkt_get_end(ssh); 1018 debug("Server GSSAPI Error:\n%s", msg); 1019 out: 1020 free(msg); 1021 free(lang); 1022 return r; 1023 } 1024 #endif /* GSSAPI */ 1025 1026 static int 1027 userauth_none(struct ssh *ssh) 1028 { 1029 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1030 int r; 1031 1032 /* initial userauth request */ 1033 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1034 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1035 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1036 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1037 (r = sshpkt_send(ssh)) != 0) 1038 fatal_fr(r, "send packet"); 1039 return 1; 1040 } 1041 1042 static int 1043 userauth_passwd(struct ssh *ssh) 1044 { 1045 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1046 char *password, *prompt = NULL; 1047 const char *host = options.host_key_alias ? options.host_key_alias : 1048 authctxt->host; 1049 int r; 1050 1051 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1052 return 0; 1053 1054 if (authctxt->attempt_passwd != 1) 1055 error("Permission denied, please try again."); 1056 1057 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1058 password = read_passphrase(prompt, 0); 1059 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1060 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1061 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1062 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1063 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1064 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1065 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1066 (r = sshpkt_send(ssh)) != 0) 1067 fatal_fr(r, "send packet"); 1068 1069 free(prompt); 1070 if (password != NULL) 1071 freezero(password, strlen(password)); 1072 1073 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1074 &input_userauth_passwd_changereq); 1075 1076 return 1; 1077 } 1078 1079 /* 1080 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1081 */ 1082 static int 1083 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1084 { 1085 Authctxt *authctxt = ssh->authctxt; 1086 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1087 char prompt[256]; 1088 const char *host; 1089 int r; 1090 1091 debug2("input_userauth_passwd_changereq"); 1092 1093 if (authctxt == NULL) 1094 fatal("input_userauth_passwd_changereq: " 1095 "no authentication context"); 1096 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1097 1098 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1099 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1100 goto out; 1101 if (strlen(info) > 0) 1102 logit("%s", info); 1103 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1104 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1105 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1106 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1107 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1108 goto out; 1109 1110 snprintf(prompt, sizeof(prompt), 1111 "Enter %.30s@%.128s's old password: ", 1112 authctxt->server_user, host); 1113 password = read_passphrase(prompt, 0); 1114 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1115 goto out; 1116 1117 freezero(password, strlen(password)); 1118 password = NULL; 1119 while (password == NULL) { 1120 snprintf(prompt, sizeof(prompt), 1121 "Enter %.30s@%.128s's new password: ", 1122 authctxt->server_user, host); 1123 password = read_passphrase(prompt, RP_ALLOW_EOF); 1124 if (password == NULL) { 1125 /* bail out */ 1126 r = 0; 1127 goto out; 1128 } 1129 snprintf(prompt, sizeof(prompt), 1130 "Retype %.30s@%.128s's new password: ", 1131 authctxt->server_user, host); 1132 retype = read_passphrase(prompt, 0); 1133 if (strcmp(password, retype) != 0) { 1134 freezero(password, strlen(password)); 1135 logit("Mismatch; try again, EOF to quit."); 1136 password = NULL; 1137 } 1138 freezero(retype, strlen(retype)); 1139 } 1140 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1141 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1142 (r = sshpkt_send(ssh)) != 0) 1143 goto out; 1144 1145 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1146 &input_userauth_passwd_changereq); 1147 r = 0; 1148 out: 1149 if (password) 1150 freezero(password, strlen(password)); 1151 free(info); 1152 free(lang); 1153 return r; 1154 } 1155 1156 /* 1157 * Select an algorithm for publickey signatures. 1158 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1159 * 1160 * Call with ssh==NULL to ignore server-sig-algs extension list and 1161 * only attempt with the key's base signature type. 1162 */ 1163 static char * 1164 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1165 { 1166 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1167 const char *server_sig_algs; 1168 1169 /* 1170 * The signature algorithm will only differ from the key algorithm 1171 * for RSA keys/certs and when the server advertises support for 1172 * newer (SHA2) algorithms. 1173 */ 1174 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1175 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1176 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1177 /* Filter base key signature alg against our configuration */ 1178 return match_list(sshkey_ssh_name(key), 1179 options.pubkey_accepted_algos, NULL); 1180 } 1181 1182 /* 1183 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1184 * fails to advertise it via SSH2_MSG_EXT_INFO. 1185 */ 1186 server_sig_algs = ssh->kex->server_sig_algs; 1187 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1188 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1189 1190 /* 1191 * For RSA keys/certs, since these might have a different sig type: 1192 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1193 * that also appears in the supported signature algorithms list from 1194 * the server. 1195 */ 1196 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1197 while ((cp = strsep(&allowed, ",")) != NULL) { 1198 if (sshkey_type_from_name(cp) != key->type) 1199 continue; 1200 tmp = match_list(sshkey_sigalg_by_name(cp), 1201 server_sig_algs, NULL); 1202 if (tmp != NULL) 1203 alg = xstrdup(cp); 1204 free(tmp); 1205 if (alg != NULL) 1206 break; 1207 } 1208 free(oallowed); 1209 return alg; 1210 } 1211 1212 static int 1213 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1214 const u_char *data, size_t datalen, u_int compat, const char *alg) 1215 { 1216 struct sshkey *sign_key = NULL, *prv = NULL; 1217 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1218 struct notifier_ctx *notifier = NULL; 1219 char *fp = NULL, *pin = NULL, *prompt = NULL; 1220 1221 *sigp = NULL; 1222 *lenp = 0; 1223 1224 /* The agent supports this key. */ 1225 if (id->key != NULL && id->agent_fd != -1) { 1226 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1227 data, datalen, alg, compat); 1228 } 1229 1230 /* 1231 * We have already loaded the private key or the private key is 1232 * stored in external hardware. 1233 */ 1234 if (id->key != NULL && 1235 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1236 sign_key = id->key; 1237 is_agent = 1; 1238 } else { 1239 /* Load the private key from the file. */ 1240 if ((prv = load_identity_file(id)) == NULL) 1241 return SSH_ERR_KEY_NOT_FOUND; 1242 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1243 error_f("private key %s contents do not match public", 1244 id->filename); 1245 r = SSH_ERR_KEY_NOT_FOUND; 1246 goto out; 1247 } 1248 sign_key = prv; 1249 } 1250 retry_pin: 1251 /* Prompt for touch for non-agent FIDO keys that request UP */ 1252 if (!is_agent && sshkey_is_sk(sign_key) && 1253 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1254 /* XXX should batch mode just skip these? */ 1255 if ((fp = sshkey_fingerprint(sign_key, 1256 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1257 fatal_f("fingerprint failed"); 1258 notifier = notify_start(options.batch_mode, 1259 "Confirm user presence for key %s %s", 1260 sshkey_type(sign_key), fp); 1261 free(fp); 1262 } 1263 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1264 alg, options.sk_provider, pin, compat)) != 0) { 1265 debug_fr(r, "sshkey_sign"); 1266 if (!retried && pin == NULL && !is_agent && 1267 sshkey_is_sk(sign_key) && 1268 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1269 notify_complete(notifier, NULL); 1270 notifier = NULL; 1271 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1272 sshkey_type(sign_key), id->filename); 1273 pin = read_passphrase(prompt, 0); 1274 retried = 1; 1275 goto retry_pin; 1276 } 1277 goto out; 1278 } 1279 1280 /* 1281 * PKCS#11 tokens may not support all signature algorithms, 1282 * so check what we get back. 1283 */ 1284 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1285 debug_fr(r, "sshkey_check_sigtype"); 1286 goto out; 1287 } 1288 /* success */ 1289 r = 0; 1290 out: 1291 free(prompt); 1292 if (pin != NULL) 1293 freezero(pin, strlen(pin)); 1294 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1295 sshkey_free(prv); 1296 return r; 1297 } 1298 1299 static int 1300 id_filename_matches(Identity *id, Identity *private_id) 1301 { 1302 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1303 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1304 size_t i, slen; 1305 1306 if (strcmp(id->filename, private_id->filename) == 0) 1307 return 1; 1308 for (i = 0; suffixes[i]; i++) { 1309 slen = strlen(suffixes[i]); 1310 if (len > slen && plen == len - slen && 1311 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1312 memcmp(id->filename, private_id->filename, plen) == 0) 1313 return 1; 1314 } 1315 return 0; 1316 } 1317 1318 static int 1319 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1320 { 1321 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1322 struct sshbuf *b = NULL; 1323 Identity *private_id, *sign_id = NULL; 1324 u_char *signature = NULL; 1325 size_t slen = 0, skip = 0; 1326 int r, fallback_sigtype, sent = 0; 1327 char *alg = NULL, *fp = NULL; 1328 const char *loc = "", *method = "publickey"; 1329 int hostbound = 0; 1330 1331 /* prefer host-bound pubkey signatures if supported by server */ 1332 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1333 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1334 hostbound = 1; 1335 method = "publickey-hostbound-v00@openssh.com"; 1336 } 1337 1338 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1339 SSH_FP_DEFAULT)) == NULL) 1340 return 0; 1341 1342 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1343 1344 /* 1345 * If the key is an certificate, try to find a matching private key 1346 * and use it to complete the signature. 1347 * If no such private key exists, fall back to trying the certificate 1348 * key itself in case it has a private half already loaded. 1349 * This will try to set sign_id to the private key that will perform 1350 * the signature. 1351 */ 1352 if (sshkey_is_cert(id->key)) { 1353 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1354 if (sshkey_equal_public(id->key, private_id->key) && 1355 id->key->type != private_id->key->type) { 1356 sign_id = private_id; 1357 break; 1358 } 1359 } 1360 /* 1361 * Exact key matches are preferred, but also allow 1362 * filename matches for non-PKCS#11/agent keys that 1363 * didn't load public keys. This supports the case 1364 * of keeping just a private key file and public 1365 * certificate on disk. 1366 */ 1367 if (sign_id == NULL && 1368 !id->isprivate && id->agent_fd == -1 && 1369 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1370 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1371 if (private_id->key == NULL && 1372 id_filename_matches(id, private_id)) { 1373 sign_id = private_id; 1374 break; 1375 } 1376 } 1377 } 1378 if (sign_id != NULL) { 1379 debug2_f("using private key \"%s\"%s for " 1380 "certificate", sign_id->filename, 1381 sign_id->agent_fd != -1 ? " from agent" : ""); 1382 } else { 1383 debug_f("no separate private key for certificate " 1384 "\"%s\"", id->filename); 1385 } 1386 } 1387 1388 /* 1389 * If the above didn't select another identity to do the signing 1390 * then default to the one we started with. 1391 */ 1392 if (sign_id == NULL) 1393 sign_id = id; 1394 1395 /* assemble and sign data */ 1396 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1397 free(alg); 1398 slen = 0; 1399 signature = NULL; 1400 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1401 id->key)) == NULL) { 1402 error_f("no mutual signature supported"); 1403 goto out; 1404 } 1405 debug3_f("signing using %s %s", alg, fp); 1406 1407 sshbuf_free(b); 1408 if ((b = sshbuf_new()) == NULL) 1409 fatal_f("sshbuf_new failed"); 1410 if (ssh->compat & SSH_OLD_SESSIONID) { 1411 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1412 fatal_fr(r, "sshbuf_putb"); 1413 } else { 1414 if ((r = sshbuf_put_stringb(b, 1415 ssh->kex->session_id)) != 0) 1416 fatal_fr(r, "sshbuf_put_stringb"); 1417 } 1418 skip = sshbuf_len(b); 1419 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1420 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1421 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1422 (r = sshbuf_put_cstring(b, method)) != 0 || 1423 (r = sshbuf_put_u8(b, 1)) != 0 || 1424 (r = sshbuf_put_cstring(b, alg)) != 0 || 1425 (r = sshkey_puts(id->key, b)) != 0) { 1426 fatal_fr(r, "assemble signed data"); 1427 } 1428 if (hostbound) { 1429 if (ssh->kex->initial_hostkey == NULL) { 1430 fatal_f("internal error: initial hostkey " 1431 "not recorded"); 1432 } 1433 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1434 fatal_fr(r, "assemble %s hostkey", method); 1435 } 1436 /* generate signature */ 1437 r = identity_sign(sign_id, &signature, &slen, 1438 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1439 if (r == 0) 1440 break; 1441 else if (r == SSH_ERR_KEY_NOT_FOUND) 1442 goto out; /* soft failure */ 1443 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1444 !fallback_sigtype) { 1445 if (sign_id->agent_fd != -1) 1446 loc = "agent "; 1447 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1448 loc = "token "; 1449 logit("%skey %s %s returned incorrect signature type", 1450 loc, sshkey_type(id->key), fp); 1451 continue; 1452 } 1453 error_fr(r, "signing failed for %s \"%s\"%s", 1454 sshkey_type(sign_id->key), sign_id->filename, 1455 id->agent_fd != -1 ? " from agent" : ""); 1456 goto out; 1457 } 1458 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1459 fatal_f("no signature"); 1460 1461 /* append signature */ 1462 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1463 fatal_fr(r, "append signature"); 1464 1465 #ifdef DEBUG_PK 1466 sshbuf_dump(b, stderr); 1467 #endif 1468 /* skip session id and packet type */ 1469 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1470 fatal_fr(r, "consume"); 1471 1472 /* put remaining data from buffer into packet */ 1473 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1474 (r = sshpkt_putb(ssh, b)) != 0 || 1475 (r = sshpkt_send(ssh)) != 0) 1476 fatal_fr(r, "enqueue request"); 1477 1478 /* success */ 1479 sent = 1; 1480 1481 out: 1482 free(fp); 1483 free(alg); 1484 sshbuf_free(b); 1485 freezero(signature, slen); 1486 return sent; 1487 } 1488 1489 static int 1490 send_pubkey_test(struct ssh *ssh, Identity *id) 1491 { 1492 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1493 u_char *blob = NULL; 1494 char *alg = NULL; 1495 size_t bloblen; 1496 u_int have_sig = 0; 1497 int sent = 0, r; 1498 1499 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1500 debug_f("no mutual signature algorithm"); 1501 goto out; 1502 } 1503 1504 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1505 /* we cannot handle this key */ 1506 debug3_f("cannot handle key"); 1507 goto out; 1508 } 1509 /* register callback for USERAUTH_PK_OK message */ 1510 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1511 1512 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1513 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1514 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1515 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1516 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1517 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1518 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1519 (r = sshpkt_send(ssh)) != 0) 1520 fatal_fr(r, "send packet"); 1521 sent = 1; 1522 1523 out: 1524 free(alg); 1525 free(blob); 1526 return sent; 1527 } 1528 1529 static struct sshkey * 1530 load_identity_file(Identity *id) 1531 { 1532 struct sshkey *private = NULL; 1533 char prompt[300], *passphrase, *comment; 1534 int r, quit = 0, i; 1535 struct stat st; 1536 1537 if (stat(id->filename, &st) == -1) { 1538 do_log2(id->userprovided ? 1539 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1540 "no such identity: %s: %s", id->filename, strerror(errno)); 1541 return NULL; 1542 } 1543 snprintf(prompt, sizeof prompt, 1544 "Enter passphrase for key '%.100s': ", id->filename); 1545 for (i = 0; i <= options.number_of_password_prompts; i++) { 1546 if (i == 0) 1547 passphrase = ""; 1548 else { 1549 passphrase = read_passphrase(prompt, 0); 1550 if (*passphrase == '\0') { 1551 debug2("no passphrase given, try next key"); 1552 free(passphrase); 1553 break; 1554 } 1555 } 1556 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1557 passphrase, &private, &comment))) { 1558 case 0: 1559 break; 1560 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1561 if (options.batch_mode) { 1562 quit = 1; 1563 break; 1564 } 1565 if (i != 0) 1566 debug2("bad passphrase given, try again..."); 1567 break; 1568 case SSH_ERR_SYSTEM_ERROR: 1569 if (errno == ENOENT) { 1570 debug2_r(r, "Load key \"%s\"", id->filename); 1571 quit = 1; 1572 break; 1573 } 1574 /* FALLTHROUGH */ 1575 default: 1576 error_r(r, "Load key \"%s\"", id->filename); 1577 quit = 1; 1578 break; 1579 } 1580 if (private != NULL && sshkey_is_sk(private) && 1581 options.sk_provider == NULL) { 1582 debug("key \"%s\" is an authenticator-hosted key, " 1583 "but no provider specified", id->filename); 1584 sshkey_free(private); 1585 private = NULL; 1586 quit = 1; 1587 } 1588 if (!quit && (r = sshkey_check_rsa_length(private, 1589 options.required_rsa_size)) != 0) { 1590 debug_fr(r, "Skipping key %s", id->filename); 1591 sshkey_free(private); 1592 private = NULL; 1593 quit = 1; 1594 } 1595 if (!quit && private != NULL && id->agent_fd == -1 && 1596 !(id->key && id->isprivate)) 1597 maybe_add_key_to_agent(id->filename, private, comment, 1598 passphrase); 1599 if (i > 0) 1600 freezero(passphrase, strlen(passphrase)); 1601 free(comment); 1602 if (private != NULL || quit) 1603 break; 1604 } 1605 return private; 1606 } 1607 1608 static int 1609 key_type_allowed_by_config(struct sshkey *key) 1610 { 1611 if (match_pattern_list(sshkey_ssh_name(key), 1612 options.pubkey_accepted_algos, 0) == 1) 1613 return 1; 1614 1615 /* RSA keys/certs might be allowed by alternate signature types */ 1616 switch (key->type) { 1617 case KEY_RSA: 1618 if (match_pattern_list("rsa-sha2-512", 1619 options.pubkey_accepted_algos, 0) == 1) 1620 return 1; 1621 if (match_pattern_list("rsa-sha2-256", 1622 options.pubkey_accepted_algos, 0) == 1) 1623 return 1; 1624 break; 1625 case KEY_RSA_CERT: 1626 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1627 options.pubkey_accepted_algos, 0) == 1) 1628 return 1; 1629 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1630 options.pubkey_accepted_algos, 0) == 1) 1631 return 1; 1632 break; 1633 } 1634 return 0; 1635 } 1636 1637 /* obtain a list of keys from the agent */ 1638 static int 1639 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1640 struct ssh_identitylist **idlistp) 1641 { 1642 int r, agent_fd; 1643 struct ssh_identitylist *idlist; 1644 1645 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1646 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1647 debug_fr(r, "ssh_get_authentication_socket"); 1648 return r; 1649 } 1650 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1651 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1652 debug_f("bound agent to hostkey"); 1653 else 1654 debug2_fr(r, "ssh_agent_bind_hostkey"); 1655 1656 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1657 debug_fr(r, "ssh_fetch_identitylist"); 1658 close(agent_fd); 1659 return r; 1660 } 1661 /* success */ 1662 *agent_fdp = agent_fd; 1663 *idlistp = idlist; 1664 debug_f("agent returned %zu keys", idlist->nkeys); 1665 return 0; 1666 } 1667 1668 /* 1669 * try keys in the following order: 1670 * 1. certificates listed in the config file 1671 * 2. other input certificates 1672 * 3. agent keys that are found in the config file 1673 * 4. other agent keys 1674 * 5. keys that are only listed in the config file 1675 */ 1676 static void 1677 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1678 { 1679 struct identity *id, *id2, *tmp; 1680 struct idlist agent, files, *preferred; 1681 struct sshkey *key; 1682 int agent_fd = -1, i, r, found; 1683 size_t j; 1684 struct ssh_identitylist *idlist; 1685 char *ident; 1686 1687 TAILQ_INIT(&agent); /* keys from the agent */ 1688 TAILQ_INIT(&files); /* keys from the config file */ 1689 preferred = &authctxt->keys; 1690 TAILQ_INIT(preferred); /* preferred order of keys */ 1691 1692 /* list of keys stored in the filesystem and PKCS#11 */ 1693 for (i = 0; i < options.num_identity_files; i++) { 1694 key = options.identity_keys[i]; 1695 if (key && key->cert && 1696 key->cert->type != SSH2_CERT_TYPE_USER) { 1697 debug_f("ignoring certificate %s: not a user " 1698 "certificate", options.identity_files[i]); 1699 continue; 1700 } 1701 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1702 debug_f("ignoring authenticator-hosted key %s as no " 1703 "SecurityKeyProvider has been specified", 1704 options.identity_files[i]); 1705 continue; 1706 } 1707 options.identity_keys[i] = NULL; 1708 id = xcalloc(1, sizeof(*id)); 1709 id->agent_fd = -1; 1710 id->key = key; 1711 id->filename = xstrdup(options.identity_files[i]); 1712 id->userprovided = options.identity_file_userprovided[i]; 1713 TAILQ_INSERT_TAIL(&files, id, next); 1714 } 1715 /* list of certificates specified by user */ 1716 for (i = 0; i < options.num_certificate_files; i++) { 1717 key = options.certificates[i]; 1718 if (!sshkey_is_cert(key) || key->cert == NULL || 1719 key->cert->type != SSH2_CERT_TYPE_USER) { 1720 debug_f("ignoring certificate %s: not a user " 1721 "certificate", options.identity_files[i]); 1722 continue; 1723 } 1724 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1725 debug_f("ignoring authenticator-hosted key " 1726 "certificate %s as no " 1727 "SecurityKeyProvider has been specified", 1728 options.identity_files[i]); 1729 continue; 1730 } 1731 id = xcalloc(1, sizeof(*id)); 1732 id->agent_fd = -1; 1733 id->key = key; 1734 id->filename = xstrdup(options.certificate_files[i]); 1735 id->userprovided = options.certificate_file_userprovided[i]; 1736 TAILQ_INSERT_TAIL(preferred, id, next); 1737 } 1738 /* list of keys supported by the agent */ 1739 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1740 for (j = 0; j < idlist->nkeys; j++) { 1741 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1742 options.required_rsa_size)) != 0) { 1743 debug_fr(r, "ignoring %s agent key", 1744 sshkey_ssh_name(idlist->keys[j])); 1745 continue; 1746 } 1747 found = 0; 1748 TAILQ_FOREACH(id, &files, next) { 1749 /* 1750 * agent keys from the config file are 1751 * preferred 1752 */ 1753 if (sshkey_equal(idlist->keys[j], id->key)) { 1754 TAILQ_REMOVE(&files, id, next); 1755 TAILQ_INSERT_TAIL(preferred, id, next); 1756 id->agent_fd = agent_fd; 1757 found = 1; 1758 break; 1759 } 1760 } 1761 if (!found && !options.identities_only) { 1762 id = xcalloc(1, sizeof(*id)); 1763 /* XXX "steals" key/comment from idlist */ 1764 id->key = idlist->keys[j]; 1765 id->filename = idlist->comments[j]; 1766 idlist->keys[j] = NULL; 1767 idlist->comments[j] = NULL; 1768 id->agent_fd = agent_fd; 1769 TAILQ_INSERT_TAIL(&agent, id, next); 1770 } 1771 } 1772 ssh_free_identitylist(idlist); 1773 /* append remaining agent keys */ 1774 TAILQ_CONCAT(preferred, &agent, next); 1775 authctxt->agent_fd = agent_fd; 1776 } 1777 /* Prefer PKCS11 keys that are explicitly listed */ 1778 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1779 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1780 continue; 1781 found = 0; 1782 TAILQ_FOREACH(id2, &files, next) { 1783 if (id2->key == NULL || 1784 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1785 continue; 1786 if (sshkey_equal(id->key, id2->key)) { 1787 TAILQ_REMOVE(&files, id, next); 1788 TAILQ_INSERT_TAIL(preferred, id, next); 1789 found = 1; 1790 break; 1791 } 1792 } 1793 /* If IdentitiesOnly set and key not found then don't use it */ 1794 if (!found && options.identities_only) { 1795 TAILQ_REMOVE(&files, id, next); 1796 freezero(id, sizeof(*id)); 1797 } 1798 } 1799 /* append remaining keys from the config file */ 1800 TAILQ_CONCAT(preferred, &files, next); 1801 /* finally, filter by PubkeyAcceptedAlgorithms */ 1802 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1803 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1804 debug("Skipping %s key %s - " 1805 "corresponding algo not in PubkeyAcceptedAlgorithms", 1806 sshkey_ssh_name(id->key), id->filename); 1807 TAILQ_REMOVE(preferred, id, next); 1808 sshkey_free(id->key); 1809 free(id->filename); 1810 memset(id, 0, sizeof(*id)); 1811 continue; 1812 } 1813 } 1814 /* List the keys we plan on using */ 1815 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1816 ident = format_identity(id); 1817 debug("Will attempt key: %s", ident); 1818 free(ident); 1819 } 1820 debug2_f("done"); 1821 } 1822 1823 static void 1824 pubkey_cleanup(struct ssh *ssh) 1825 { 1826 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1827 Identity *id; 1828 1829 if (authctxt->agent_fd != -1) { 1830 ssh_close_authentication_socket(authctxt->agent_fd); 1831 authctxt->agent_fd = -1; 1832 } 1833 for (id = TAILQ_FIRST(&authctxt->keys); id; 1834 id = TAILQ_FIRST(&authctxt->keys)) { 1835 TAILQ_REMOVE(&authctxt->keys, id, next); 1836 sshkey_free(id->key); 1837 free(id->filename); 1838 free(id); 1839 } 1840 } 1841 1842 static void 1843 pubkey_reset(Authctxt *authctxt) 1844 { 1845 Identity *id; 1846 1847 TAILQ_FOREACH(id, &authctxt->keys, next) 1848 id->tried = 0; 1849 } 1850 1851 static int 1852 userauth_pubkey(struct ssh *ssh) 1853 { 1854 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1855 Identity *id; 1856 int sent = 0; 1857 char *ident; 1858 1859 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1860 if (id->tried++) 1861 return (0); 1862 /* move key to the end of the queue */ 1863 TAILQ_REMOVE(&authctxt->keys, id, next); 1864 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1865 /* 1866 * send a test message if we have the public key. for 1867 * encrypted keys we cannot do this and have to load the 1868 * private key instead 1869 */ 1870 if (id->key != NULL) { 1871 if (id->key != NULL) { 1872 ident = format_identity(id); 1873 debug("Offering public key: %s", ident); 1874 free(ident); 1875 sent = send_pubkey_test(ssh, id); 1876 } 1877 } else { 1878 debug("Trying private key: %s", id->filename); 1879 id->key = load_identity_file(id); 1880 if (id->key != NULL) { 1881 if (id->key != NULL) { 1882 id->isprivate = 1; 1883 sent = sign_and_send_pubkey(ssh, id); 1884 } 1885 sshkey_free(id->key); 1886 id->key = NULL; 1887 id->isprivate = 0; 1888 } 1889 } 1890 if (sent) 1891 return (sent); 1892 } 1893 return (0); 1894 } 1895 1896 /* 1897 * Send userauth request message specifying keyboard-interactive method. 1898 */ 1899 static int 1900 userauth_kbdint(struct ssh *ssh) 1901 { 1902 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1903 int r; 1904 1905 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1906 return 0; 1907 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1908 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1909 debug3("userauth_kbdint: disable: no info_req_seen"); 1910 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1911 return 0; 1912 } 1913 1914 debug2("userauth_kbdint"); 1915 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1916 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1917 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1918 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1919 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1920 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1921 options.kbd_interactive_devices : "")) != 0 || 1922 (r = sshpkt_send(ssh)) != 0) 1923 fatal_fr(r, "send packet"); 1924 1925 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1926 return 1; 1927 } 1928 1929 /* 1930 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1931 */ 1932 static int 1933 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1934 { 1935 Authctxt *authctxt = ssh->authctxt; 1936 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1937 char *display_prompt = NULL, *response = NULL; 1938 u_char echo = 0; 1939 u_int num_prompts, i; 1940 int r; 1941 1942 debug2_f("entering"); 1943 1944 if (authctxt == NULL) 1945 fatal_f("no authentication context"); 1946 1947 authctxt->info_req_seen = 1; 1948 1949 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1950 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1951 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1952 goto out; 1953 if (strlen(name) > 0) 1954 logit("%s", name); 1955 if (strlen(inst) > 0) 1956 logit("%s", inst); 1957 1958 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1959 goto out; 1960 /* 1961 * Begin to build info response packet based on prompts requested. 1962 * We commit to providing the correct number of responses, so if 1963 * further on we run into a problem that prevents this, we have to 1964 * be sure and clean this up and send a correct error response. 1965 */ 1966 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1967 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1968 goto out; 1969 1970 debug2_f("num_prompts %d", num_prompts); 1971 for (i = 0; i < num_prompts; i++) { 1972 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1973 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1974 goto out; 1975 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1976 authctxt->server_user, options.host_key_alias ? 1977 options.host_key_alias : authctxt->host, prompt) == -1) 1978 fatal_f("asmprintf failed"); 1979 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1980 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1981 goto out; 1982 freezero(response, strlen(response)); 1983 free(prompt); 1984 free(display_prompt); 1985 display_prompt = response = prompt = NULL; 1986 } 1987 /* done with parsing incoming message. */ 1988 if ((r = sshpkt_get_end(ssh)) != 0 || 1989 (r = sshpkt_add_padding(ssh, 64)) != 0) 1990 goto out; 1991 r = sshpkt_send(ssh); 1992 out: 1993 if (response) 1994 freezero(response, strlen(response)); 1995 free(prompt); 1996 free(display_prompt); 1997 free(name); 1998 free(inst); 1999 free(lang); 2000 return r; 2001 } 2002 2003 static int 2004 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2005 const u_char *data, size_t datalen) 2006 { 2007 struct sshbuf *b; 2008 struct stat st; 2009 pid_t pid; 2010 int r, to[2], from[2], status; 2011 int sock = ssh_packet_get_connection_in(ssh); 2012 u_char rversion = 0, version = 2; 2013 void (*osigchld)(int); 2014 2015 *sigp = NULL; 2016 *lenp = 0; 2017 2018 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2019 error_f("not installed: %s", strerror(errno)); 2020 return -1; 2021 } 2022 if (fflush(stdout) != 0) { 2023 error_f("fflush: %s", strerror(errno)); 2024 return -1; 2025 } 2026 if (pipe(to) == -1) { 2027 error_f("pipe: %s", strerror(errno)); 2028 return -1; 2029 } 2030 if (pipe(from) == -1) { 2031 error_f("pipe: %s", strerror(errno)); 2032 return -1; 2033 } 2034 if ((pid = fork()) == -1) { 2035 error_f("fork: %s", strerror(errno)); 2036 return -1; 2037 } 2038 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2039 if (pid == 0) { 2040 close(from[0]); 2041 if (dup2(from[1], STDOUT_FILENO) == -1) 2042 fatal_f("dup2: %s", strerror(errno)); 2043 close(to[1]); 2044 if (dup2(to[0], STDIN_FILENO) == -1) 2045 fatal_f("dup2: %s", strerror(errno)); 2046 close(from[1]); 2047 close(to[0]); 2048 2049 if (dup2(sock, STDERR_FILENO + 1) == -1) 2050 fatal_f("dup2: %s", strerror(errno)); 2051 sock = STDERR_FILENO + 1; 2052 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2053 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2054 closefrom(sock + 1); 2055 2056 debug3_f("[child] pid=%ld, exec %s", 2057 (long)getpid(), _PATH_SSH_KEY_SIGN); 2058 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2059 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2060 strerror(errno)); 2061 } 2062 close(from[1]); 2063 close(to[0]); 2064 sock = STDERR_FILENO + 1; 2065 2066 if ((b = sshbuf_new()) == NULL) 2067 fatal_f("sshbuf_new failed"); 2068 /* send # of sock, data to be signed */ 2069 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2070 (r = sshbuf_put_string(b, data, datalen)) != 0) 2071 fatal_fr(r, "buffer error"); 2072 if (ssh_msg_send(to[1], version, b) == -1) 2073 fatal_f("couldn't send request"); 2074 sshbuf_reset(b); 2075 r = ssh_msg_recv(from[0], b); 2076 close(from[0]); 2077 close(to[1]); 2078 if (r < 0) { 2079 error_f("no reply"); 2080 goto fail; 2081 } 2082 2083 errno = 0; 2084 while (waitpid(pid, &status, 0) == -1) { 2085 if (errno != EINTR) { 2086 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2087 goto fail; 2088 } 2089 } 2090 if (!WIFEXITED(status)) { 2091 error_f("exited abnormally"); 2092 goto fail; 2093 } 2094 if (WEXITSTATUS(status) != 0) { 2095 error_f("exited with status %d", WEXITSTATUS(status)); 2096 goto fail; 2097 } 2098 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2099 error_fr(r, "buffer error"); 2100 goto fail; 2101 } 2102 if (rversion != version) { 2103 error_f("bad version"); 2104 goto fail; 2105 } 2106 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2107 error_fr(r, "buffer error"); 2108 fail: 2109 ssh_signal(SIGCHLD, osigchld); 2110 sshbuf_free(b); 2111 return -1; 2112 } 2113 ssh_signal(SIGCHLD, osigchld); 2114 sshbuf_free(b); 2115 2116 return 0; 2117 } 2118 2119 static int 2120 userauth_hostbased(struct ssh *ssh) 2121 { 2122 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2123 struct sshkey *private = NULL; 2124 struct sshbuf *b = NULL; 2125 u_char *sig = NULL, *keyblob = NULL; 2126 char *fp = NULL, *chost = NULL, *lname = NULL; 2127 size_t siglen = 0, keylen = 0; 2128 int i, r, success = 0; 2129 2130 if (authctxt->ktypes == NULL) { 2131 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2132 authctxt->ktypes = authctxt->oktypes; 2133 } 2134 2135 /* 2136 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2137 * trying each hostkey that matches the type in turn. 2138 */ 2139 for (;;) { 2140 if (authctxt->active_ktype == NULL) 2141 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2142 if (authctxt->active_ktype == NULL || 2143 *authctxt->active_ktype == '\0') 2144 break; 2145 debug3_f("trying key type %s", authctxt->active_ktype); 2146 2147 /* check for a useful key */ 2148 private = NULL; 2149 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2150 if (authctxt->sensitive->keys[i] == NULL || 2151 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2152 continue; 2153 if (!sshkey_match_keyname_to_sigalgs( 2154 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2155 authctxt->active_ktype)) 2156 continue; 2157 /* we take and free the key */ 2158 private = authctxt->sensitive->keys[i]; 2159 authctxt->sensitive->keys[i] = NULL; 2160 break; 2161 } 2162 /* Found one */ 2163 if (private != NULL) 2164 break; 2165 /* No more keys of this type; advance */ 2166 authctxt->active_ktype = NULL; 2167 } 2168 if (private == NULL) { 2169 free(authctxt->oktypes); 2170 authctxt->oktypes = authctxt->ktypes = NULL; 2171 authctxt->active_ktype = NULL; 2172 debug("No more client hostkeys for hostbased authentication."); 2173 goto out; 2174 } 2175 2176 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2177 SSH_FP_DEFAULT)) == NULL) { 2178 error_f("sshkey_fingerprint failed"); 2179 goto out; 2180 } 2181 debug_f("trying hostkey %s %s using sigalg %s", 2182 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2183 2184 /* figure out a name for the client host */ 2185 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2186 if (lname == NULL) { 2187 error_f("cannot get local ipaddr/name"); 2188 goto out; 2189 } 2190 2191 /* XXX sshbuf_put_stringf? */ 2192 xasprintf(&chost, "%s.", lname); 2193 debug2_f("chost %s", chost); 2194 2195 /* construct data */ 2196 if ((b = sshbuf_new()) == NULL) { 2197 error_f("sshbuf_new failed"); 2198 goto out; 2199 } 2200 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2201 error_fr(r, "sshkey_to_blob"); 2202 goto out; 2203 } 2204 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2205 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2206 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2207 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2208 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2209 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2210 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2211 (r = sshbuf_put_cstring(b, chost)) != 0 || 2212 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2213 error_fr(r, "buffer error"); 2214 goto out; 2215 } 2216 2217 #ifdef DEBUG_PK 2218 sshbuf_dump(b, stderr); 2219 #endif 2220 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2221 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2222 error("sign using hostkey %s %s failed", 2223 sshkey_ssh_name(private), fp); 2224 goto out; 2225 } 2226 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2227 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2228 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2229 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2230 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2231 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2232 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2233 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2234 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2235 (r = sshpkt_send(ssh)) != 0) { 2236 error_fr(r, "packet error"); 2237 goto out; 2238 } 2239 success = 1; 2240 2241 out: 2242 if (sig != NULL) 2243 freezero(sig, siglen); 2244 free(keyblob); 2245 free(lname); 2246 free(fp); 2247 free(chost); 2248 sshkey_free(private); 2249 sshbuf_free(b); 2250 2251 return success; 2252 } 2253 2254 /* find auth method */ 2255 2256 /* 2257 * given auth method name, if configurable options permit this method fill 2258 * in auth_ident field and return true, otherwise return false. 2259 */ 2260 static int 2261 authmethod_is_enabled(Authmethod *method) 2262 { 2263 if (method == NULL) 2264 return 0; 2265 /* return false if options indicate this method is disabled */ 2266 if (method->enabled == NULL || *method->enabled == 0) 2267 return 0; 2268 /* return false if batch mode is enabled but method needs interactive mode */ 2269 if (method->batch_flag != NULL && *method->batch_flag != 0) 2270 return 0; 2271 return 1; 2272 } 2273 2274 static Authmethod * 2275 authmethod_lookup(const char *name) 2276 { 2277 Authmethod *method = NULL; 2278 if (name != NULL) 2279 for (method = authmethods; method->name != NULL; method++) 2280 if (strcmp(name, method->name) == 0) 2281 return method; 2282 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2283 return NULL; 2284 } 2285 2286 /* XXX internal state */ 2287 static Authmethod *current = NULL; 2288 static char *supported = NULL; 2289 static char *preferred = NULL; 2290 2291 /* 2292 * Given the authentication method list sent by the server, return the 2293 * next method we should try. If the server initially sends a nil list, 2294 * use a built-in default list. 2295 */ 2296 static Authmethod * 2297 authmethod_get(char *authlist) 2298 { 2299 char *name = NULL; 2300 u_int next; 2301 2302 /* Use a suitable default if we're passed a nil list. */ 2303 if (authlist == NULL || strlen(authlist) == 0) 2304 authlist = options.preferred_authentications; 2305 2306 if (supported == NULL || strcmp(authlist, supported) != 0) { 2307 debug3("start over, passed a different list %s", authlist); 2308 free(supported); 2309 supported = xstrdup(authlist); 2310 preferred = options.preferred_authentications; 2311 debug3("preferred %s", preferred); 2312 current = NULL; 2313 } else if (current != NULL && authmethod_is_enabled(current)) 2314 return current; 2315 2316 for (;;) { 2317 if ((name = match_list(preferred, supported, &next)) == NULL) { 2318 debug("No more authentication methods to try."); 2319 current = NULL; 2320 return NULL; 2321 } 2322 preferred += next; 2323 debug3("authmethod_lookup %s", name); 2324 debug3("remaining preferred: %s", preferred); 2325 if ((current = authmethod_lookup(name)) != NULL && 2326 authmethod_is_enabled(current)) { 2327 debug3("authmethod_is_enabled %s", name); 2328 debug("Next authentication method: %s", name); 2329 free(name); 2330 return current; 2331 } 2332 free(name); 2333 } 2334 } 2335 2336 static char * 2337 authmethods_get(void) 2338 { 2339 Authmethod *method = NULL; 2340 struct sshbuf *b; 2341 char *list; 2342 int r; 2343 2344 if ((b = sshbuf_new()) == NULL) 2345 fatal_f("sshbuf_new failed"); 2346 for (method = authmethods; method->name != NULL; method++) { 2347 if (authmethod_is_enabled(method)) { 2348 if ((r = sshbuf_putf(b, "%s%s", 2349 sshbuf_len(b) ? "," : "", method->name)) != 0) 2350 fatal_fr(r, "buffer error"); 2351 } 2352 } 2353 if ((list = sshbuf_dup_string(b)) == NULL) 2354 fatal_f("sshbuf_dup_string failed"); 2355 sshbuf_free(b); 2356 return list; 2357 } 2358