1/* $OpenBSD: sshconnect2.c,v 1.372 2024/01/08 00:34:34 djm Exp $ */ 2/* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include "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 */ 83extern char *client_version_string; 84extern char *server_version_string; 85extern Options options; 86 87/* 88 * SSH2 key exchange 89 */ 90 91static char *xxx_host; 92static struct sockaddr *xxx_hostaddr; 93static const struct ssh_conn_info *xxx_conn_info; 94 95static int 96verify_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 */ 110static char * 111first_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 121static char * 122order_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, hostname); 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 219void 220ssh_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 *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 (use_known_hosts_order) 253 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 254 255 kex_proposal_populate_entries(ssh, myproposal, 256 options.kex_algorithms, options.ciphers, options.macs, 257 compression_alg_list(options.compression), 258 hkalgs ? hkalgs : options.hostkeyalgorithms); 259 260 free(hkalgs); 261 262 /* start key exchange */ 263 if ((r = kex_setup(ssh, myproposal)) != 0) 264 fatal_r(r, "kex_setup"); 265#ifdef WITH_OPENSSL 266 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 267 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 269 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 270 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 272 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 273# ifdef OPENSSL_HAS_ECC 274 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 275# endif 276#endif 277 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 278 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 279 ssh->kex->verify_host_key=&verify_host_key_callback; 280 281 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 282 kex_proposal_free_entries(myproposal); 283 284#ifdef DEBUG_KEXDH 285 /* send 1st encrypted/maced/compressed message */ 286 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 287 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 288 (r = sshpkt_send(ssh)) != 0 || 289 (r = ssh_packet_write_wait(ssh)) != 0) 290 fatal_fr(r, "send packet"); 291#endif 292} 293 294/* 295 * Authenticate user 296 */ 297 298typedef struct cauthctxt Authctxt; 299typedef struct cauthmethod Authmethod; 300typedef struct identity Identity; 301typedef struct idlist Idlist; 302 303struct identity { 304 TAILQ_ENTRY(identity) next; 305 int agent_fd; /* >=0 if agent supports key */ 306 struct sshkey *key; /* public/private key */ 307 char *filename; /* comment for agent-only keys */ 308 int tried; 309 int isprivate; /* key points to the private key */ 310 int userprovided; 311}; 312TAILQ_HEAD(idlist, identity); 313 314struct cauthctxt { 315 const char *server_user; 316 const char *local_user; 317 const char *host; 318 const char *service; 319 struct cauthmethod *method; 320 sig_atomic_t success; 321 char *authlist; 322#ifdef GSSAPI 323 /* gssapi */ 324 gss_OID_set gss_supported_mechs; 325 u_int mech_tried; 326#endif 327 /* pubkey */ 328 struct idlist keys; 329 int agent_fd; 330 /* hostbased */ 331 Sensitive *sensitive; 332 char *oktypes, *ktypes; 333 const char *active_ktype; 334 /* kbd-interactive */ 335 int info_req_seen; 336 int attempt_kbdint; 337 /* password */ 338 int attempt_passwd; 339 /* generic */ 340 void *methoddata; 341}; 342 343struct cauthmethod { 344 char *name; /* string to compare against server's list */ 345 int (*userauth)(struct ssh *ssh); 346 void (*cleanup)(struct ssh *ssh); 347 int *enabled; /* flag in option struct that enables method */ 348 int *batch_flag; /* flag in option struct that disables method */ 349}; 350 351static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 352static int input_userauth_success(int, u_int32_t, struct ssh *); 353static int input_userauth_failure(int, u_int32_t, struct ssh *); 354static int input_userauth_banner(int, u_int32_t, struct ssh *); 355static int input_userauth_error(int, u_int32_t, struct ssh *); 356static int input_userauth_info_req(int, u_int32_t, struct ssh *); 357static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 358static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 359 360static int userauth_none(struct ssh *); 361static int userauth_pubkey(struct ssh *); 362static int userauth_passwd(struct ssh *); 363static int userauth_kbdint(struct ssh *); 364static int userauth_hostbased(struct ssh *); 365 366#ifdef GSSAPI 367static int userauth_gssapi(struct ssh *); 368static void userauth_gssapi_cleanup(struct ssh *); 369static int input_gssapi_response(int type, u_int32_t, struct ssh *); 370static int input_gssapi_token(int type, u_int32_t, struct ssh *); 371static int input_gssapi_error(int, u_int32_t, struct ssh *); 372static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 373#endif 374 375void userauth(struct ssh *, char *); 376 377static void pubkey_cleanup(struct ssh *); 378static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 379static void pubkey_prepare(struct ssh *, Authctxt *); 380static void pubkey_reset(Authctxt *); 381static struct sshkey *load_identity_file(Identity *); 382 383static Authmethod *authmethod_get(char *authlist); 384static Authmethod *authmethod_lookup(const char *name); 385static char *authmethods_get(void); 386 387Authmethod authmethods[] = { 388#ifdef GSSAPI 389 {"gssapi-with-mic", 390 userauth_gssapi, 391 userauth_gssapi_cleanup, 392 &options.gss_authentication, 393 NULL}, 394#endif 395 {"hostbased", 396 userauth_hostbased, 397 NULL, 398 &options.hostbased_authentication, 399 NULL}, 400 {"publickey", 401 userauth_pubkey, 402 NULL, 403 &options.pubkey_authentication, 404 NULL}, 405 {"keyboard-interactive", 406 userauth_kbdint, 407 NULL, 408 &options.kbd_interactive_authentication, 409 &options.batch_mode}, 410 {"password", 411 userauth_passwd, 412 NULL, 413 &options.password_authentication, 414 &options.batch_mode}, 415 {"none", 416 userauth_none, 417 NULL, 418 NULL, 419 NULL}, 420 {NULL, NULL, NULL, NULL, NULL} 421}; 422 423void 424ssh_userauth2(struct ssh *ssh, const char *local_user, 425 const char *server_user, char *host, Sensitive *sensitive) 426{ 427 Authctxt authctxt; 428 int r; 429 430 if (options.preferred_authentications == NULL) 431 options.preferred_authentications = authmethods_get(); 432 433 /* setup authentication context */ 434 memset(&authctxt, 0, sizeof(authctxt)); 435 authctxt.server_user = server_user; 436 authctxt.local_user = local_user; 437 authctxt.host = host; 438 authctxt.service = "ssh-connection"; /* service name */ 439 authctxt.success = 0; 440 authctxt.method = authmethod_lookup("none"); 441 authctxt.authlist = NULL; 442 authctxt.methoddata = NULL; 443 authctxt.sensitive = sensitive; 444 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 445 authctxt.info_req_seen = 0; 446 authctxt.attempt_kbdint = 0; 447 authctxt.attempt_passwd = 0; 448#if GSSAPI 449 authctxt.gss_supported_mechs = NULL; 450 authctxt.mech_tried = 0; 451#endif 452 authctxt.agent_fd = -1; 453 if (authctxt.method == NULL) 454 fatal_f("internal error: cannot send userauth none request"); 455 456 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 457 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 458 (r = sshpkt_send(ssh)) != 0) 459 fatal_fr(r, "send packet"); 460 461 ssh->authctxt = &authctxt; 462 ssh_dispatch_init(ssh, &input_userauth_error); 463 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info); 464 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 465 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 466 pubkey_cleanup(ssh); 467#ifdef GSSAPI 468 if (authctxt.gss_supported_mechs != NULL) { 469 u_int ms; 470 471 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs); 472 authctxt.gss_supported_mechs = NULL; 473 } 474#endif 475 ssh->authctxt = NULL; 476 477 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 478 479 if (!authctxt.success) 480 fatal("Authentication failed."); 481 if (ssh_packet_connection_is_on_socket(ssh)) { 482 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 484 authctxt.method->name); 485 } else { 486 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 487 authctxt.method->name); 488 } 489} 490 491static int 492input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 493{ 494 int r; 495 496 if (ssh_packet_remaining(ssh) > 0) { 497 char *reply; 498 499 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 500 goto out; 501 debug2("service_accept: %s", reply); 502 free(reply); 503 } else { 504 debug2("buggy server: service_accept w/o service"); 505 } 506 if ((r = sshpkt_get_end(ssh)) != 0) 507 goto out; 508 debug("SSH2_MSG_SERVICE_ACCEPT received"); 509 510 /* initial userauth request */ 511 userauth_none(ssh); 512 513 /* accept EXT_INFO at any time during userauth */ 514 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ? 515 &kex_input_ext_info : &input_userauth_error); 516 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 517 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 519 r = 0; 520 out: 521 return r; 522} 523 524void 525userauth(struct ssh *ssh, char *authlist) 526{ 527 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 528 529 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 530 authctxt->method->cleanup(ssh); 531 532 free(authctxt->methoddata); 533 authctxt->methoddata = NULL; 534 if (authlist == NULL) { 535 authlist = authctxt->authlist; 536 } else { 537 free(authctxt->authlist); 538 authctxt->authlist = authlist; 539 } 540 for (;;) { 541 Authmethod *method = authmethod_get(authlist); 542 if (method == NULL) 543 fatal("%s@%s: Permission denied (%s).", 544 authctxt->server_user, authctxt->host, authlist); 545 authctxt->method = method; 546 547 /* reset the per method handler */ 548 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 549 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 550 551 /* and try new method */ 552 if (method->userauth(ssh) != 0) { 553 debug2("we sent a %s packet, wait for reply", method->name); 554 break; 555 } else { 556 debug2("we did not send a packet, disable method"); 557 method->enabled = NULL; 558 } 559 } 560} 561 562static int 563input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 564{ 565 fatal_f("bad message during authentication: type %d", type); 566 return 0; 567} 568 569static int 570input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 571{ 572 char *msg = NULL; 573 size_t len; 574 int r; 575 576 debug3_f("entering"); 577 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 578 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 579 goto out; 580 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 581 fmprintf(stderr, "%s", msg); 582 r = 0; 583 out: 584 free(msg); 585 return r; 586} 587 588static int 589input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 590{ 591 Authctxt *authctxt = ssh->authctxt; 592 593 if (authctxt == NULL) 594 fatal_f("no authentication context"); 595 free(authctxt->authlist); 596 authctxt->authlist = NULL; 597 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 598 authctxt->method->cleanup(ssh); 599 free(authctxt->methoddata); 600 authctxt->methoddata = NULL; 601 authctxt->success = 1; /* break out */ 602 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error); 603 return 0; 604} 605 606#if 0 607static int 608input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 609{ 610 Authctxt *authctxt = ssh->authctxt; 611 612 if (authctxt == NULL) 613 fatal_f("no authentication context"); 614 615 fatal("Unexpected authentication success during %s.", 616 authctxt->method->name); 617 return 0; 618} 619#endif 620 621static int 622input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 623{ 624 Authctxt *authctxt = ssh->authctxt; 625 char *authlist = NULL; 626 u_char partial; 627 628 if (authctxt == NULL) 629 fatal("input_userauth_failure: no authentication context"); 630 631 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 632 sshpkt_get_u8(ssh, &partial) != 0 || 633 sshpkt_get_end(ssh) != 0) 634 goto out; 635 636 if (partial != 0) { 637 verbose("Authenticated using \"%s\" with partial success.", 638 authctxt->method->name); 639 /* reset state */ 640 pubkey_reset(authctxt); 641 } 642 debug("Authentications that can continue: %s", authlist); 643 644 userauth(ssh, authlist); 645 authlist = NULL; 646 out: 647 free(authlist); 648 return 0; 649} 650 651/* 652 * Format an identity for logging including filename, key type, fingerprint 653 * and location (agent, etc.). Caller must free. 654 */ 655static char * 656format_identity(Identity *id) 657{ 658 char *fp = NULL, *ret = NULL; 659 const char *note = ""; 660 661 if (id->key != NULL) { 662 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 663 SSH_FP_DEFAULT); 664 } 665 if (id->key) { 666 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 667 note = " token"; 668 else if (sshkey_is_sk(id->key)) 669 note = " authenticator"; 670 } 671 xasprintf(&ret, "%s %s%s%s%s%s%s", 672 id->filename, 673 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 674 fp ? fp : "", 675 id->userprovided ? " explicit" : "", note, 676 id->agent_fd != -1 ? " agent" : ""); 677 free(fp); 678 return ret; 679} 680 681static int 682input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 683{ 684 Authctxt *authctxt = ssh->authctxt; 685 struct sshkey *key = NULL; 686 Identity *id = NULL; 687 int pktype, found = 0, sent = 0; 688 size_t blen; 689 char *pkalg = NULL, *fp = NULL, *ident = NULL; 690 u_char *pkblob = NULL; 691 int r; 692 693 if (authctxt == NULL) 694 fatal("input_userauth_pk_ok: no authentication context"); 695 696 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 697 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 698 (r = sshpkt_get_end(ssh)) != 0) 699 goto done; 700 701 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 702 debug_f("server sent unknown pkalg %s", pkalg); 703 goto done; 704 } 705 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 706 debug_r(r, "no key from blob. pkalg %s", pkalg); 707 goto done; 708 } 709 if (key->type != pktype) { 710 error("input_userauth_pk_ok: type mismatch " 711 "for decoded key (received %d, expected %d)", 712 key->type, pktype); 713 goto done; 714 } 715 716 /* 717 * search keys in the reverse order, because last candidate has been 718 * moved to the end of the queue. this also avoids confusion by 719 * duplicate keys 720 */ 721 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 722 if (sshkey_equal(key, id->key)) { 723 found = 1; 724 break; 725 } 726 } 727 if (!found || id == NULL) { 728 fp = sshkey_fingerprint(key, options.fingerprint_hash, 729 SSH_FP_DEFAULT); 730 error_f("server replied with unknown key: %s %s", 731 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 732 goto done; 733 } 734 ident = format_identity(id); 735 debug("Server accepts key: %s", ident); 736 sent = sign_and_send_pubkey(ssh, id); 737 r = 0; 738 done: 739 sshkey_free(key); 740 free(ident); 741 free(fp); 742 free(pkalg); 743 free(pkblob); 744 745 /* try another method if we did not send a packet */ 746 if (r == 0 && sent == 0) 747 userauth(ssh, NULL); 748 return r; 749} 750 751#ifdef GSSAPI 752static int 753userauth_gssapi(struct ssh *ssh) 754{ 755 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 756 Gssctxt *gssctxt = NULL; 757 OM_uint32 min; 758 int r, ok = 0; 759 gss_OID mech = NULL; 760 761 /* Try one GSSAPI method at a time, rather than sending them all at 762 * once. */ 763 764 if (authctxt->gss_supported_mechs == NULL) 765 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 766 767 /* Check to see whether the mechanism is usable before we offer it */ 768 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 769 !ok) { 770 mech = &authctxt->gss_supported_mechs-> 771 elements[authctxt->mech_tried]; 772 /* My DER encoding requires length<128 */ 773 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 774 mech, authctxt->host)) { 775 ok = 1; /* Mechanism works */ 776 } else { 777 authctxt->mech_tried++; 778 } 779 } 780 781 if (!ok || mech == NULL) 782 return 0; 783 784 authctxt->methoddata=(void *)gssctxt; 785 786 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 787 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 788 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 789 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 790 (r = sshpkt_put_u32(ssh, 1)) != 0 || 791 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 792 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 793 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 794 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 795 (r = sshpkt_send(ssh)) != 0) 796 fatal_fr(r, "send packet"); 797 798 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 800 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 801 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 802 803 authctxt->mech_tried++; /* Move along to next candidate */ 804 805 return 1; 806} 807 808static void 809userauth_gssapi_cleanup(struct ssh *ssh) 810{ 811 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 812 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 813 814 ssh_gssapi_delete_ctx(&gssctxt); 815 authctxt->methoddata = NULL; 816} 817 818static OM_uint32 819process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 820{ 821 Authctxt *authctxt = ssh->authctxt; 822 Gssctxt *gssctxt = authctxt->methoddata; 823 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 824 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 825 gss_buffer_desc gssbuf; 826 OM_uint32 status, ms, flags; 827 int r; 828 829 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 830 recv_tok, &send_tok, &flags); 831 832 if (send_tok.length > 0) { 833 u_char type = GSS_ERROR(status) ? 834 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 835 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 836 837 if ((r = sshpkt_start(ssh, type)) != 0 || 838 (r = sshpkt_put_string(ssh, send_tok.value, 839 send_tok.length)) != 0 || 840 (r = sshpkt_send(ssh)) != 0) 841 fatal_fr(r, "send %u packet", type); 842 843 gss_release_buffer(&ms, &send_tok); 844 } 845 846 if (status == GSS_S_COMPLETE) { 847 /* send either complete or MIC, depending on mechanism */ 848 if (!(flags & GSS_C_INTEG_FLAG)) { 849 if ((r = sshpkt_start(ssh, 850 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 851 (r = sshpkt_send(ssh)) != 0) 852 fatal_fr(r, "send completion"); 853 } else { 854 struct sshbuf *b; 855 856 if ((b = sshbuf_new()) == NULL) 857 fatal_f("sshbuf_new failed"); 858 ssh_gssapi_buildmic(b, authctxt->server_user, 859 authctxt->service, "gssapi-with-mic", 860 ssh->kex->session_id); 861 862 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 863 fatal_f("sshbuf_mutable_ptr failed"); 864 gssbuf.length = sshbuf_len(b); 865 866 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 867 868 if (!GSS_ERROR(status)) { 869 if ((r = sshpkt_start(ssh, 870 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 871 (r = sshpkt_put_string(ssh, mic.value, 872 mic.length)) != 0 || 873 (r = sshpkt_send(ssh)) != 0) 874 fatal_fr(r, "send MIC"); 875 } 876 877 sshbuf_free(b); 878 gss_release_buffer(&ms, &mic); 879 } 880 } 881 882 return status; 883} 884 885static int 886input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 887{ 888 Authctxt *authctxt = ssh->authctxt; 889 Gssctxt *gssctxt; 890 size_t oidlen; 891 u_char *oidv = NULL; 892 int r; 893 894 if (authctxt == NULL) 895 fatal("input_gssapi_response: no authentication context"); 896 gssctxt = authctxt->methoddata; 897 898 /* Setup our OID */ 899 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 900 goto done; 901 902 if (oidlen <= 2 || 903 oidv[0] != SSH_GSS_OIDTYPE || 904 oidv[1] != oidlen - 2) { 905 debug("Badly encoded mechanism OID received"); 906 userauth(ssh, NULL); 907 goto ok; 908 } 909 910 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 911 fatal("Server returned different OID than expected"); 912 913 if ((r = sshpkt_get_end(ssh)) != 0) 914 goto done; 915 916 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 917 /* Start again with next method on list */ 918 debug("Trying to start again"); 919 userauth(ssh, NULL); 920 goto ok; 921 } 922 ok: 923 r = 0; 924 done: 925 free(oidv); 926 return r; 927} 928 929static int 930input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 931{ 932 Authctxt *authctxt = ssh->authctxt; 933 gss_buffer_desc recv_tok; 934 u_char *p = NULL; 935 size_t len; 936 OM_uint32 status; 937 int r; 938 939 if (authctxt == NULL) 940 fatal("input_gssapi_response: no authentication context"); 941 942 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 943 (r = sshpkt_get_end(ssh)) != 0) 944 goto out; 945 946 recv_tok.value = p; 947 recv_tok.length = len; 948 status = process_gssapi_token(ssh, &recv_tok); 949 950 /* Start again with the next method in the list */ 951 if (GSS_ERROR(status)) { 952 userauth(ssh, NULL); 953 /* ok */ 954 } 955 r = 0; 956 out: 957 free(p); 958 return r; 959} 960 961static int 962input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 963{ 964 Authctxt *authctxt = ssh->authctxt; 965 Gssctxt *gssctxt; 966 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 967 gss_buffer_desc recv_tok; 968 OM_uint32 ms; 969 u_char *p = NULL; 970 size_t len; 971 int r; 972 973 if (authctxt == NULL) 974 fatal("input_gssapi_response: no authentication context"); 975 gssctxt = authctxt->methoddata; 976 977 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 978 (r = sshpkt_get_end(ssh)) != 0) { 979 free(p); 980 return r; 981 } 982 983 /* Stick it into GSSAPI and see what it says */ 984 recv_tok.value = p; 985 recv_tok.length = len; 986 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 987 &recv_tok, &send_tok, NULL); 988 free(p); 989 gss_release_buffer(&ms, &send_tok); 990 991 /* Server will be returning a failed packet after this one */ 992 return 0; 993} 994 995static int 996input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 997{ 998 char *msg = NULL; 999 char *lang = NULL; 1000 int r; 1001 1002 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1003 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1004 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1005 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1006 goto out; 1007 r = sshpkt_get_end(ssh); 1008 debug("Server GSSAPI Error:\n%s", msg); 1009 out: 1010 free(msg); 1011 free(lang); 1012 return r; 1013} 1014#endif /* GSSAPI */ 1015 1016static int 1017userauth_none(struct ssh *ssh) 1018{ 1019 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1020 int r; 1021 1022 /* initial userauth request */ 1023 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1024 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1025 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1026 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1027 (r = sshpkt_send(ssh)) != 0) 1028 fatal_fr(r, "send packet"); 1029 return 1; 1030} 1031 1032static int 1033userauth_passwd(struct ssh *ssh) 1034{ 1035 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1036 char *password, *prompt = NULL; 1037 const char *host = options.host_key_alias ? options.host_key_alias : 1038 authctxt->host; 1039 int r; 1040 1041 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1042 return 0; 1043 1044 if (authctxt->attempt_passwd != 1) 1045 error("Permission denied, please try again."); 1046 1047 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1048 password = read_passphrase(prompt, 0); 1049 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1050 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1051 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1052 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1053 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1055 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1056 (r = sshpkt_send(ssh)) != 0) 1057 fatal_fr(r, "send packet"); 1058 1059 free(prompt); 1060 if (password != NULL) 1061 freezero(password, strlen(password)); 1062 1063 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1064 &input_userauth_passwd_changereq); 1065 1066 return 1; 1067} 1068 1069/* 1070 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1071 */ 1072static int 1073input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1074{ 1075 Authctxt *authctxt = ssh->authctxt; 1076 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1077 char prompt[256]; 1078 const char *host; 1079 int r; 1080 1081 debug2("input_userauth_passwd_changereq"); 1082 1083 if (authctxt == NULL) 1084 fatal("input_userauth_passwd_changereq: " 1085 "no authentication context"); 1086 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1087 1088 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1089 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1090 goto out; 1091 if (strlen(info) > 0) 1092 logit("%s", info); 1093 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1094 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1095 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1096 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1097 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1098 goto out; 1099 1100 snprintf(prompt, sizeof(prompt), 1101 "Enter %.30s@%.128s's old password: ", 1102 authctxt->server_user, host); 1103 password = read_passphrase(prompt, 0); 1104 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1105 goto out; 1106 1107 freezero(password, strlen(password)); 1108 password = NULL; 1109 while (password == NULL) { 1110 snprintf(prompt, sizeof(prompt), 1111 "Enter %.30s@%.128s's new password: ", 1112 authctxt->server_user, host); 1113 password = read_passphrase(prompt, RP_ALLOW_EOF); 1114 if (password == NULL) { 1115 /* bail out */ 1116 r = 0; 1117 goto out; 1118 } 1119 snprintf(prompt, sizeof(prompt), 1120 "Retype %.30s@%.128s's new password: ", 1121 authctxt->server_user, host); 1122 retype = read_passphrase(prompt, 0); 1123 if (strcmp(password, retype) != 0) { 1124 freezero(password, strlen(password)); 1125 logit("Mismatch; try again, EOF to quit."); 1126 password = NULL; 1127 } 1128 freezero(retype, strlen(retype)); 1129 } 1130 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1131 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1132 (r = sshpkt_send(ssh)) != 0) 1133 goto out; 1134 1135 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1136 &input_userauth_passwd_changereq); 1137 r = 0; 1138 out: 1139 if (password) 1140 freezero(password, strlen(password)); 1141 free(info); 1142 free(lang); 1143 return r; 1144} 1145 1146/* 1147 * Select an algorithm for publickey signatures. 1148 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1149 * 1150 * Call with ssh==NULL to ignore server-sig-algs extension list and 1151 * only attempt with the key's base signature type. 1152 */ 1153static char * 1154key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1155{ 1156 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1157 const char *server_sig_algs; 1158 1159 /* 1160 * The signature algorithm will only differ from the key algorithm 1161 * for RSA keys/certs and when the server advertises support for 1162 * newer (SHA2) algorithms. 1163 */ 1164 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1165 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1166 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1167 /* Filter base key signature alg against our configuration */ 1168 return match_list(sshkey_ssh_name(key), 1169 options.pubkey_accepted_algos, NULL); 1170 } 1171 1172 /* 1173 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1174 * fails to advertise it via SSH2_MSG_EXT_INFO. 1175 */ 1176 server_sig_algs = ssh->kex->server_sig_algs; 1177 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1178 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1179 1180 /* 1181 * For RSA keys/certs, since these might have a different sig type: 1182 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1183 * that also appears in the supported signature algorithms list from 1184 * the server. 1185 */ 1186 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1187 while ((cp = strsep(&allowed, ",")) != NULL) { 1188 if (sshkey_type_from_name(cp) != key->type) 1189 continue; 1190 tmp = match_list(sshkey_sigalg_by_name(cp), 1191 server_sig_algs, NULL); 1192 if (tmp != NULL) 1193 alg = xstrdup(cp); 1194 free(tmp); 1195 if (alg != NULL) 1196 break; 1197 } 1198 free(oallowed); 1199 return alg; 1200} 1201 1202static int 1203identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1204 const u_char *data, size_t datalen, u_int compat, const char *alg) 1205{ 1206 struct sshkey *sign_key = NULL, *prv = NULL; 1207 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1208 struct notifier_ctx *notifier = NULL; 1209 char *fp = NULL, *pin = NULL, *prompt = NULL; 1210 1211 *sigp = NULL; 1212 *lenp = 0; 1213 1214 /* The agent supports this key. */ 1215 if (id->key != NULL && id->agent_fd != -1) { 1216 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1217 data, datalen, alg, compat); 1218 } 1219 1220 /* 1221 * We have already loaded the private key or the private key is 1222 * stored in external hardware. 1223 */ 1224 if (id->key != NULL && 1225 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1226 sign_key = id->key; 1227 is_agent = 1; 1228 } else { 1229 /* Load the private key from the file. */ 1230 if ((prv = load_identity_file(id)) == NULL) 1231 return SSH_ERR_KEY_NOT_FOUND; 1232 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1233 error_f("private key %s contents do not match public", 1234 id->filename); 1235 r = SSH_ERR_KEY_NOT_FOUND; 1236 goto out; 1237 } 1238 sign_key = prv; 1239 } 1240 retry_pin: 1241 /* Prompt for touch for non-agent FIDO keys that request UP */ 1242 if (!is_agent && sshkey_is_sk(sign_key) && 1243 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1244 /* XXX should batch mode just skip these? */ 1245 if ((fp = sshkey_fingerprint(sign_key, 1246 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1247 fatal_f("fingerprint failed"); 1248 notifier = notify_start(options.batch_mode, 1249 "Confirm user presence for key %s %s", 1250 sshkey_type(sign_key), fp); 1251 free(fp); 1252 } 1253 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1254 alg, options.sk_provider, pin, compat)) != 0) { 1255 debug_fr(r, "sshkey_sign"); 1256 if (!retried && pin == NULL && !is_agent && 1257 sshkey_is_sk(sign_key) && 1258 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1259 notify_complete(notifier, NULL); 1260 notifier = NULL; 1261 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1262 sshkey_type(sign_key), id->filename); 1263 pin = read_passphrase(prompt, 0); 1264 retried = 1; 1265 goto retry_pin; 1266 } 1267 goto out; 1268 } 1269 1270 /* 1271 * PKCS#11 tokens may not support all signature algorithms, 1272 * so check what we get back. 1273 */ 1274 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1275 debug_fr(r, "sshkey_check_sigtype"); 1276 goto out; 1277 } 1278 /* success */ 1279 r = 0; 1280 out: 1281 free(prompt); 1282 if (pin != NULL) 1283 freezero(pin, strlen(pin)); 1284 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1285 sshkey_free(prv); 1286 return r; 1287} 1288 1289static int 1290id_filename_matches(Identity *id, Identity *private_id) 1291{ 1292 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1293 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1294 size_t i, slen; 1295 1296 if (strcmp(id->filename, private_id->filename) == 0) 1297 return 1; 1298 for (i = 0; suffixes[i]; i++) { 1299 slen = strlen(suffixes[i]); 1300 if (len > slen && plen == len - slen && 1301 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1302 memcmp(id->filename, private_id->filename, plen) == 0) 1303 return 1; 1304 } 1305 return 0; 1306} 1307 1308static int 1309sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1310{ 1311 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1312 struct sshbuf *b = NULL; 1313 Identity *private_id, *sign_id = NULL; 1314 u_char *signature = NULL; 1315 size_t slen = 0, skip = 0; 1316 int r, fallback_sigtype, sent = 0; 1317 char *alg = NULL, *fp = NULL; 1318 const char *loc = "", *method = "publickey"; 1319 int hostbound = 0; 1320 1321 /* prefer host-bound pubkey signatures if supported by server */ 1322 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1323 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1324 hostbound = 1; 1325 method = "publickey-hostbound-v00@openssh.com"; 1326 } 1327 1328 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1329 SSH_FP_DEFAULT)) == NULL) 1330 return 0; 1331 1332 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1333 1334 /* 1335 * If the key is an certificate, try to find a matching private key 1336 * and use it to complete the signature. 1337 * If no such private key exists, fall back to trying the certificate 1338 * key itself in case it has a private half already loaded. 1339 * This will try to set sign_id to the private key that will perform 1340 * the signature. 1341 */ 1342 if (sshkey_is_cert(id->key)) { 1343 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1344 if (sshkey_equal_public(id->key, private_id->key) && 1345 id->key->type != private_id->key->type) { 1346 sign_id = private_id; 1347 break; 1348 } 1349 } 1350 /* 1351 * Exact key matches are preferred, but also allow 1352 * filename matches for non-PKCS#11/agent keys that 1353 * didn't load public keys. This supports the case 1354 * of keeping just a private key file and public 1355 * certificate on disk. 1356 */ 1357 if (sign_id == NULL && 1358 !id->isprivate && id->agent_fd == -1 && 1359 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1360 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1361 if (private_id->key == NULL && 1362 id_filename_matches(id, private_id)) { 1363 sign_id = private_id; 1364 break; 1365 } 1366 } 1367 } 1368 if (sign_id != NULL) { 1369 debug2_f("using private key \"%s\"%s for " 1370 "certificate", sign_id->filename, 1371 sign_id->agent_fd != -1 ? " from agent" : ""); 1372 } else { 1373 debug_f("no separate private key for certificate " 1374 "\"%s\"", id->filename); 1375 } 1376 } 1377 1378 /* 1379 * If the above didn't select another identity to do the signing 1380 * then default to the one we started with. 1381 */ 1382 if (sign_id == NULL) 1383 sign_id = id; 1384 1385 /* assemble and sign data */ 1386 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1387 free(alg); 1388 slen = 0; 1389 signature = NULL; 1390 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1391 id->key)) == NULL) { 1392 error_f("no mutual signature supported"); 1393 goto out; 1394 } 1395 debug3_f("signing using %s %s", alg, fp); 1396 1397 sshbuf_free(b); 1398 if ((b = sshbuf_new()) == NULL) 1399 fatal_f("sshbuf_new failed"); 1400 if (ssh->compat & SSH_OLD_SESSIONID) { 1401 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1402 fatal_fr(r, "sshbuf_putb"); 1403 } else { 1404 if ((r = sshbuf_put_stringb(b, 1405 ssh->kex->session_id)) != 0) 1406 fatal_fr(r, "sshbuf_put_stringb"); 1407 } 1408 skip = sshbuf_len(b); 1409 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1410 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1411 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1412 (r = sshbuf_put_cstring(b, method)) != 0 || 1413 (r = sshbuf_put_u8(b, 1)) != 0 || 1414 (r = sshbuf_put_cstring(b, alg)) != 0 || 1415 (r = sshkey_puts(id->key, b)) != 0) { 1416 fatal_fr(r, "assemble signed data"); 1417 } 1418 if (hostbound) { 1419 if (ssh->kex->initial_hostkey == NULL) { 1420 fatal_f("internal error: initial hostkey " 1421 "not recorded"); 1422 } 1423 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1424 fatal_fr(r, "assemble %s hostkey", method); 1425 } 1426 /* generate signature */ 1427 r = identity_sign(sign_id, &signature, &slen, 1428 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1429 if (r == 0) 1430 break; 1431 else if (r == SSH_ERR_KEY_NOT_FOUND) 1432 goto out; /* soft failure */ 1433 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1434 !fallback_sigtype) { 1435 if (sign_id->agent_fd != -1) 1436 loc = "agent "; 1437 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1438 loc = "token "; 1439 logit("%skey %s %s returned incorrect signature type", 1440 loc, sshkey_type(id->key), fp); 1441 continue; 1442 } 1443 error_fr(r, "signing failed for %s \"%s\"%s", 1444 sshkey_type(sign_id->key), sign_id->filename, 1445 id->agent_fd != -1 ? " from agent" : ""); 1446 goto out; 1447 } 1448 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1449 fatal_f("no signature"); 1450 1451 /* append signature */ 1452 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1453 fatal_fr(r, "append signature"); 1454 1455#ifdef DEBUG_PK 1456 sshbuf_dump(b, stderr); 1457#endif 1458 /* skip session id and packet type */ 1459 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1460 fatal_fr(r, "consume"); 1461 1462 /* put remaining data from buffer into packet */ 1463 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1464 (r = sshpkt_putb(ssh, b)) != 0 || 1465 (r = sshpkt_send(ssh)) != 0) 1466 fatal_fr(r, "enqueue request"); 1467 1468 /* success */ 1469 sent = 1; 1470 1471 out: 1472 free(fp); 1473 free(alg); 1474 sshbuf_free(b); 1475 freezero(signature, slen); 1476 return sent; 1477} 1478 1479static int 1480send_pubkey_test(struct ssh *ssh, Identity *id) 1481{ 1482 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1483 u_char *blob = NULL; 1484 char *alg = NULL; 1485 size_t bloblen; 1486 u_int have_sig = 0; 1487 int sent = 0, r; 1488 1489 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1490 debug_f("no mutual signature algorithm"); 1491 goto out; 1492 } 1493 1494 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1495 /* we cannot handle this key */ 1496 debug3_f("cannot handle key"); 1497 goto out; 1498 } 1499 /* register callback for USERAUTH_PK_OK message */ 1500 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1501 1502 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1503 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1504 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1505 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1506 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1507 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1508 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1509 (r = sshpkt_send(ssh)) != 0) 1510 fatal_fr(r, "send packet"); 1511 sent = 1; 1512 1513 out: 1514 free(alg); 1515 free(blob); 1516 return sent; 1517} 1518 1519static struct sshkey * 1520load_identity_file(Identity *id) 1521{ 1522 struct sshkey *private = NULL; 1523 char prompt[300], *passphrase, *comment; 1524 int r, quit = 0, i; 1525 struct stat st; 1526 1527 if (stat(id->filename, &st) == -1) { 1528 do_log2(id->userprovided ? 1529 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1530 "no such identity: %s: %s", id->filename, strerror(errno)); 1531 return NULL; 1532 } 1533 snprintf(prompt, sizeof prompt, 1534 "Enter passphrase for key '%.100s': ", id->filename); 1535 for (i = 0; i <= options.number_of_password_prompts; i++) { 1536 if (i == 0) 1537 passphrase = ""; 1538 else { 1539 passphrase = read_passphrase(prompt, 0); 1540 if (*passphrase == '\0') { 1541 debug2("no passphrase given, try next key"); 1542 free(passphrase); 1543 break; 1544 } 1545 } 1546 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1547 passphrase, &private, &comment))) { 1548 case 0: 1549 break; 1550 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1551 if (options.batch_mode) { 1552 quit = 1; 1553 break; 1554 } 1555 if (i != 0) 1556 debug2("bad passphrase given, try again..."); 1557 break; 1558 case SSH_ERR_SYSTEM_ERROR: 1559 if (errno == ENOENT) { 1560 debug2_r(r, "Load key \"%s\"", id->filename); 1561 quit = 1; 1562 break; 1563 } 1564 /* FALLTHROUGH */ 1565 default: 1566 error_r(r, "Load key \"%s\"", id->filename); 1567 quit = 1; 1568 break; 1569 } 1570 if (private != NULL && sshkey_is_sk(private) && 1571 options.sk_provider == NULL) { 1572 debug("key \"%s\" is an authenticator-hosted key, " 1573 "but no provider specified", id->filename); 1574 sshkey_free(private); 1575 private = NULL; 1576 quit = 1; 1577 } 1578 if (!quit && (r = sshkey_check_rsa_length(private, 1579 options.required_rsa_size)) != 0) { 1580 debug_fr(r, "Skipping key %s", id->filename); 1581 sshkey_free(private); 1582 private = NULL; 1583 quit = 1; 1584 } 1585 if (!quit && private != NULL && id->agent_fd == -1 && 1586 !(id->key && id->isprivate)) 1587 maybe_add_key_to_agent(id->filename, private, comment, 1588 passphrase); 1589 if (i > 0) 1590 freezero(passphrase, strlen(passphrase)); 1591 free(comment); 1592 if (private != NULL || quit) 1593 break; 1594 } 1595 return private; 1596} 1597 1598static int 1599key_type_allowed_by_config(struct sshkey *key) 1600{ 1601 if (match_pattern_list(sshkey_ssh_name(key), 1602 options.pubkey_accepted_algos, 0) == 1) 1603 return 1; 1604 1605 /* RSA keys/certs might be allowed by alternate signature types */ 1606 switch (key->type) { 1607 case KEY_RSA: 1608 if (match_pattern_list("rsa-sha2-512", 1609 options.pubkey_accepted_algos, 0) == 1) 1610 return 1; 1611 if (match_pattern_list("rsa-sha2-256", 1612 options.pubkey_accepted_algos, 0) == 1) 1613 return 1; 1614 break; 1615 case KEY_RSA_CERT: 1616 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1617 options.pubkey_accepted_algos, 0) == 1) 1618 return 1; 1619 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1620 options.pubkey_accepted_algos, 0) == 1) 1621 return 1; 1622 break; 1623 } 1624 return 0; 1625} 1626 1627/* obtain a list of keys from the agent */ 1628static int 1629get_agent_identities(struct ssh *ssh, int *agent_fdp, 1630 struct ssh_identitylist **idlistp) 1631{ 1632 int r, agent_fd; 1633 struct ssh_identitylist *idlist; 1634 1635 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1636 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1637 debug_fr(r, "ssh_get_authentication_socket"); 1638 return r; 1639 } 1640 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1641 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1642 debug_f("bound agent to hostkey"); 1643 else 1644 debug2_fr(r, "ssh_agent_bind_hostkey"); 1645 1646 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1647 debug_fr(r, "ssh_fetch_identitylist"); 1648 close(agent_fd); 1649 return r; 1650 } 1651 /* success */ 1652 *agent_fdp = agent_fd; 1653 *idlistp = idlist; 1654 debug_f("agent returned %zu keys", idlist->nkeys); 1655 return 0; 1656} 1657 1658/* 1659 * try keys in the following order: 1660 * 1. certificates listed in the config file 1661 * 2. other input certificates 1662 * 3. agent keys that are found in the config file 1663 * 4. other agent keys 1664 * 5. keys that are only listed in the config file 1665 */ 1666static void 1667pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1668{ 1669 struct identity *id, *id2, *tmp; 1670 struct idlist agent, files, *preferred; 1671 struct sshkey *key; 1672 int disallowed, agent_fd = -1, i, r, found; 1673 size_t j; 1674 struct ssh_identitylist *idlist; 1675 char *cp, *ident; 1676 1677 TAILQ_INIT(&agent); /* keys from the agent */ 1678 TAILQ_INIT(&files); /* keys from the config file */ 1679 preferred = &authctxt->keys; 1680 TAILQ_INIT(preferred); /* preferred order of keys */ 1681 1682 /* list of keys stored in the filesystem and PKCS#11 */ 1683 for (i = 0; i < options.num_identity_files; i++) { 1684 key = options.identity_keys[i]; 1685 if (key && key->cert && 1686 key->cert->type != SSH2_CERT_TYPE_USER) { 1687 debug_f("ignoring certificate %s: not a user " 1688 "certificate", options.identity_files[i]); 1689 continue; 1690 } 1691 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1692 debug_f("ignoring authenticator-hosted key %s as no " 1693 "SecurityKeyProvider has been specified", 1694 options.identity_files[i]); 1695 continue; 1696 } 1697 options.identity_keys[i] = NULL; 1698 id = xcalloc(1, sizeof(*id)); 1699 id->agent_fd = -1; 1700 id->key = key; 1701 id->filename = xstrdup(options.identity_files[i]); 1702 id->userprovided = options.identity_file_userprovided[i]; 1703 TAILQ_INSERT_TAIL(&files, id, next); 1704 } 1705 /* list of certificates specified by user */ 1706 for (i = 0; i < options.num_certificate_files; i++) { 1707 key = options.certificates[i]; 1708 if (!sshkey_is_cert(key) || key->cert == NULL || 1709 key->cert->type != SSH2_CERT_TYPE_USER) { 1710 debug_f("ignoring certificate %s: not a user " 1711 "certificate", options.identity_files[i]); 1712 continue; 1713 } 1714 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1715 debug_f("ignoring authenticator-hosted key " 1716 "certificate %s as no " 1717 "SecurityKeyProvider has been specified", 1718 options.identity_files[i]); 1719 continue; 1720 } 1721 id = xcalloc(1, sizeof(*id)); 1722 id->agent_fd = -1; 1723 id->key = key; 1724 id->filename = xstrdup(options.certificate_files[i]); 1725 id->userprovided = options.certificate_file_userprovided[i]; 1726 TAILQ_INSERT_TAIL(preferred, id, next); 1727 } 1728 /* list of keys supported by the agent */ 1729 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1730 for (j = 0; j < idlist->nkeys; j++) { 1731 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1732 options.required_rsa_size)) != 0) { 1733 debug_fr(r, "ignoring %s agent key", 1734 sshkey_ssh_name(idlist->keys[j])); 1735 continue; 1736 } 1737 found = 0; 1738 TAILQ_FOREACH(id, &files, next) { 1739 /* 1740 * agent keys from the config file are 1741 * preferred 1742 */ 1743 if (sshkey_equal(idlist->keys[j], id->key)) { 1744 TAILQ_REMOVE(&files, id, next); 1745 TAILQ_INSERT_TAIL(preferred, id, next); 1746 id->agent_fd = agent_fd; 1747 found = 1; 1748 break; 1749 } 1750 } 1751 if (!found && !options.identities_only) { 1752 id = xcalloc(1, sizeof(*id)); 1753 /* XXX "steals" key/comment from idlist */ 1754 id->key = idlist->keys[j]; 1755 id->filename = idlist->comments[j]; 1756 idlist->keys[j] = NULL; 1757 idlist->comments[j] = NULL; 1758 id->agent_fd = agent_fd; 1759 TAILQ_INSERT_TAIL(&agent, id, next); 1760 } 1761 } 1762 ssh_free_identitylist(idlist); 1763 /* append remaining agent keys */ 1764 TAILQ_CONCAT(preferred, &agent, next); 1765 authctxt->agent_fd = agent_fd; 1766 } 1767 /* Prefer PKCS11 keys that are explicitly listed */ 1768 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1769 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1770 continue; 1771 found = 0; 1772 TAILQ_FOREACH(id2, &files, next) { 1773 if (id2->key == NULL || 1774 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1775 continue; 1776 if (sshkey_equal(id->key, id2->key)) { 1777 TAILQ_REMOVE(&files, id, next); 1778 TAILQ_INSERT_TAIL(preferred, id, next); 1779 found = 1; 1780 break; 1781 } 1782 } 1783 /* If IdentitiesOnly set and key not found then don't use it */ 1784 if (!found && options.identities_only) { 1785 TAILQ_REMOVE(&files, id, next); 1786 freezero(id, sizeof(*id)); 1787 } 1788 } 1789 /* append remaining keys from the config file */ 1790 TAILQ_CONCAT(preferred, &files, next); 1791 /* finally, filter by PubkeyAcceptedAlgorithms */ 1792 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1793 disallowed = 0; 1794 cp = NULL; 1795 if (id->key == NULL) 1796 continue; 1797 if (!key_type_allowed_by_config(id->key)) { 1798 debug("Skipping %s key %s - corresponding algorithm " 1799 "not in PubkeyAcceptedAlgorithms", 1800 sshkey_ssh_name(id->key), id->filename); 1801 disallowed = 1; 1802 } else if (ssh->kex->server_sig_algs != NULL && 1803 (cp = key_sig_algorithm(ssh, id->key)) == NULL) { 1804 debug("Skipping %s key %s - corresponding algorithm " 1805 "not supported by server", 1806 sshkey_ssh_name(id->key), id->filename); 1807 disallowed = 1; 1808 } 1809 free(cp); 1810 if (!disallowed) 1811 continue; 1812 /* remove key */ 1813 TAILQ_REMOVE(preferred, id, next); 1814 sshkey_free(id->key); 1815 free(id->filename); 1816 memset(id, 0, sizeof(*id)); 1817 } 1818 /* List the keys we plan on using */ 1819 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1820 ident = format_identity(id); 1821 debug("Will attempt key: %s", ident); 1822 free(ident); 1823 } 1824 debug2_f("done"); 1825} 1826 1827static void 1828pubkey_cleanup(struct ssh *ssh) 1829{ 1830 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1831 Identity *id; 1832 1833 if (authctxt->agent_fd != -1) { 1834 ssh_close_authentication_socket(authctxt->agent_fd); 1835 authctxt->agent_fd = -1; 1836 } 1837 for (id = TAILQ_FIRST(&authctxt->keys); id; 1838 id = TAILQ_FIRST(&authctxt->keys)) { 1839 TAILQ_REMOVE(&authctxt->keys, id, next); 1840 sshkey_free(id->key); 1841 free(id->filename); 1842 free(id); 1843 } 1844} 1845 1846static void 1847pubkey_reset(Authctxt *authctxt) 1848{ 1849 Identity *id; 1850 1851 TAILQ_FOREACH(id, &authctxt->keys, next) 1852 id->tried = 0; 1853} 1854 1855static int 1856userauth_pubkey(struct ssh *ssh) 1857{ 1858 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1859 Identity *id; 1860 int sent = 0; 1861 char *ident; 1862 static int prepared; 1863 1864 if (!prepared) { 1865 pubkey_prepare(ssh, authctxt); 1866 prepared = 1; 1867 } 1868 1869 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1870 if (id->tried++) 1871 return (0); 1872 /* move key to the end of the queue */ 1873 TAILQ_REMOVE(&authctxt->keys, id, next); 1874 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1875 /* 1876 * send a test message if we have the public key. for 1877 * encrypted keys we cannot do this and have to load the 1878 * private key instead 1879 */ 1880 if (id->key != NULL) { 1881 ident = format_identity(id); 1882 debug("Offering public key: %s", ident); 1883 free(ident); 1884 sent = send_pubkey_test(ssh, id); 1885 } else { 1886 debug("Trying private key: %s", id->filename); 1887 id->key = load_identity_file(id); 1888 if (id->key != NULL) { 1889 if (id->key != NULL) { 1890 id->isprivate = 1; 1891 sent = sign_and_send_pubkey(ssh, id); 1892 } 1893 sshkey_free(id->key); 1894 id->key = NULL; 1895 id->isprivate = 0; 1896 } 1897 } 1898 if (sent) 1899 return (sent); 1900 } 1901 return (0); 1902} 1903 1904/* 1905 * Send userauth request message specifying keyboard-interactive method. 1906 */ 1907static int 1908userauth_kbdint(struct ssh *ssh) 1909{ 1910 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1911 int r; 1912 1913 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1914 return 0; 1915 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1916 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1917 debug3("userauth_kbdint: disable: no info_req_seen"); 1918 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1919 return 0; 1920 } 1921 1922 debug2("userauth_kbdint"); 1923 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1924 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1925 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1926 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1927 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1928 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1929 options.kbd_interactive_devices : "")) != 0 || 1930 (r = sshpkt_send(ssh)) != 0) 1931 fatal_fr(r, "send packet"); 1932 1933 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1934 return 1; 1935} 1936 1937/* 1938 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1939 */ 1940static int 1941input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1942{ 1943 Authctxt *authctxt = ssh->authctxt; 1944 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1945 char *display_prompt = NULL, *response = NULL; 1946 u_char echo = 0; 1947 u_int num_prompts, i; 1948 int r; 1949 1950 debug2_f("entering"); 1951 1952 if (authctxt == NULL) 1953 fatal_f("no authentication context"); 1954 1955 authctxt->info_req_seen = 1; 1956 1957 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1958 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1959 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1960 goto out; 1961 if (strlen(name) > 0) 1962 logit("%s", name); 1963 if (strlen(inst) > 0) 1964 logit("%s", inst); 1965 1966 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1967 goto out; 1968 /* 1969 * Begin to build info response packet based on prompts requested. 1970 * We commit to providing the correct number of responses, so if 1971 * further on we run into a problem that prevents this, we have to 1972 * be sure and clean this up and send a correct error response. 1973 */ 1974 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1975 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1976 goto out; 1977 1978 debug2_f("num_prompts %d", num_prompts); 1979 for (i = 0; i < num_prompts; i++) { 1980 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1981 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1982 goto out; 1983 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1984 authctxt->server_user, options.host_key_alias ? 1985 options.host_key_alias : authctxt->host, prompt) == -1) 1986 fatal_f("asmprintf failed"); 1987 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1988 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1989 goto out; 1990 freezero(response, strlen(response)); 1991 free(prompt); 1992 free(display_prompt); 1993 display_prompt = response = prompt = NULL; 1994 } 1995 /* done with parsing incoming message. */ 1996 if ((r = sshpkt_get_end(ssh)) != 0 || 1997 (r = sshpkt_add_padding(ssh, 64)) != 0) 1998 goto out; 1999 r = sshpkt_send(ssh); 2000 out: 2001 if (response) 2002 freezero(response, strlen(response)); 2003 free(prompt); 2004 free(display_prompt); 2005 free(name); 2006 free(inst); 2007 free(lang); 2008 return r; 2009} 2010 2011static int 2012ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2013 const u_char *data, size_t datalen) 2014{ 2015 struct sshbuf *b; 2016 struct stat st; 2017 pid_t pid; 2018 int r, to[2], from[2], status; 2019 int sock = ssh_packet_get_connection_in(ssh); 2020 u_char rversion = 0, version = 2; 2021 void (*osigchld)(int); 2022 2023 *sigp = NULL; 2024 *lenp = 0; 2025 2026 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2027 error_f("not installed: %s", strerror(errno)); 2028 return -1; 2029 } 2030 if (fflush(stdout) != 0) { 2031 error_f("fflush: %s", strerror(errno)); 2032 return -1; 2033 } 2034 if (pipe(to) == -1) { 2035 error_f("pipe: %s", strerror(errno)); 2036 return -1; 2037 } 2038 if (pipe(from) == -1) { 2039 error_f("pipe: %s", strerror(errno)); 2040 return -1; 2041 } 2042 if ((pid = fork()) == -1) { 2043 error_f("fork: %s", strerror(errno)); 2044 return -1; 2045 } 2046 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2047 if (pid == 0) { 2048 close(from[0]); 2049 if (dup2(from[1], STDOUT_FILENO) == -1) 2050 fatal_f("dup2: %s", strerror(errno)); 2051 close(to[1]); 2052 if (dup2(to[0], STDIN_FILENO) == -1) 2053 fatal_f("dup2: %s", strerror(errno)); 2054 close(from[1]); 2055 close(to[0]); 2056 2057 if (dup2(sock, STDERR_FILENO + 1) == -1) 2058 fatal_f("dup2: %s", strerror(errno)); 2059 sock = STDERR_FILENO + 1; 2060 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2061 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2062 closefrom(sock + 1); 2063 2064 debug3_f("[child] pid=%ld, exec %s", 2065 (long)getpid(), _PATH_SSH_KEY_SIGN); 2066 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2067 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2068 strerror(errno)); 2069 } 2070 close(from[1]); 2071 close(to[0]); 2072 sock = STDERR_FILENO + 1; 2073 2074 if ((b = sshbuf_new()) == NULL) 2075 fatal_f("sshbuf_new failed"); 2076 /* send # of sock, data to be signed */ 2077 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2078 (r = sshbuf_put_string(b, data, datalen)) != 0) 2079 fatal_fr(r, "buffer error"); 2080 if (ssh_msg_send(to[1], version, b) == -1) 2081 fatal_f("couldn't send request"); 2082 sshbuf_reset(b); 2083 r = ssh_msg_recv(from[0], b); 2084 close(from[0]); 2085 close(to[1]); 2086 if (r < 0) { 2087 error_f("no reply"); 2088 goto fail; 2089 } 2090 2091 errno = 0; 2092 while (waitpid(pid, &status, 0) == -1) { 2093 if (errno != EINTR) { 2094 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2095 goto fail; 2096 } 2097 } 2098 if (!WIFEXITED(status)) { 2099 error_f("exited abnormally"); 2100 goto fail; 2101 } 2102 if (WEXITSTATUS(status) != 0) { 2103 error_f("exited with status %d", WEXITSTATUS(status)); 2104 goto fail; 2105 } 2106 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2107 error_fr(r, "buffer error"); 2108 goto fail; 2109 } 2110 if (rversion != version) { 2111 error_f("bad version"); 2112 goto fail; 2113 } 2114 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2115 error_fr(r, "buffer error"); 2116 fail: 2117 ssh_signal(SIGCHLD, osigchld); 2118 sshbuf_free(b); 2119 return -1; 2120 } 2121 ssh_signal(SIGCHLD, osigchld); 2122 sshbuf_free(b); 2123 2124 return 0; 2125} 2126 2127static int 2128userauth_hostbased(struct ssh *ssh) 2129{ 2130 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2131 struct sshkey *private = NULL; 2132 struct sshbuf *b = NULL; 2133 u_char *sig = NULL, *keyblob = NULL; 2134 char *fp = NULL, *chost = NULL, *lname = NULL; 2135 size_t siglen = 0, keylen = 0; 2136 int i, r, success = 0; 2137 2138 if (authctxt->ktypes == NULL) { 2139 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2140 authctxt->ktypes = authctxt->oktypes; 2141 } 2142 2143 /* 2144 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2145 * trying each hostkey that matches the type in turn. 2146 */ 2147 for (;;) { 2148 if (authctxt->active_ktype == NULL) 2149 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2150 if (authctxt->active_ktype == NULL || 2151 *authctxt->active_ktype == '\0') 2152 break; 2153 debug3_f("trying key type %s", authctxt->active_ktype); 2154 2155 /* check for a useful key */ 2156 private = NULL; 2157 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2158 if (authctxt->sensitive->keys[i] == NULL || 2159 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2160 continue; 2161 if (!sshkey_match_keyname_to_sigalgs( 2162 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2163 authctxt->active_ktype)) 2164 continue; 2165 /* we take and free the key */ 2166 private = authctxt->sensitive->keys[i]; 2167 authctxt->sensitive->keys[i] = NULL; 2168 break; 2169 } 2170 /* Found one */ 2171 if (private != NULL) 2172 break; 2173 /* No more keys of this type; advance */ 2174 authctxt->active_ktype = NULL; 2175 } 2176 if (private == NULL) { 2177 free(authctxt->oktypes); 2178 authctxt->oktypes = authctxt->ktypes = NULL; 2179 authctxt->active_ktype = NULL; 2180 debug("No more client hostkeys for hostbased authentication."); 2181 goto out; 2182 } 2183 2184 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2185 SSH_FP_DEFAULT)) == NULL) { 2186 error_f("sshkey_fingerprint failed"); 2187 goto out; 2188 } 2189 debug_f("trying hostkey %s %s using sigalg %s", 2190 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2191 2192 /* figure out a name for the client host */ 2193 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2194 if (lname == NULL) { 2195 error_f("cannot get local ipaddr/name"); 2196 goto out; 2197 } 2198 2199 /* XXX sshbuf_put_stringf? */ 2200 xasprintf(&chost, "%s.", lname); 2201 debug2_f("chost %s", chost); 2202 2203 /* construct data */ 2204 if ((b = sshbuf_new()) == NULL) { 2205 error_f("sshbuf_new failed"); 2206 goto out; 2207 } 2208 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2209 error_fr(r, "sshkey_to_blob"); 2210 goto out; 2211 } 2212 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2213 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2214 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2215 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2216 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2217 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2218 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2219 (r = sshbuf_put_cstring(b, chost)) != 0 || 2220 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2221 error_fr(r, "buffer error"); 2222 goto out; 2223 } 2224 2225#ifdef DEBUG_PK 2226 sshbuf_dump(b, stderr); 2227#endif 2228 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2229 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2230 error("sign using hostkey %s %s failed", 2231 sshkey_ssh_name(private), fp); 2232 goto out; 2233 } 2234 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2235 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2236 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2237 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2238 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2239 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2240 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2241 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2242 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2243 (r = sshpkt_send(ssh)) != 0) { 2244 error_fr(r, "packet error"); 2245 goto out; 2246 } 2247 success = 1; 2248 2249 out: 2250 if (sig != NULL) 2251 freezero(sig, siglen); 2252 free(keyblob); 2253 free(lname); 2254 free(fp); 2255 free(chost); 2256 sshkey_free(private); 2257 sshbuf_free(b); 2258 2259 return success; 2260} 2261 2262/* find auth method */ 2263 2264/* 2265 * given auth method name, if configurable options permit this method fill 2266 * in auth_ident field and return true, otherwise return false. 2267 */ 2268static int 2269authmethod_is_enabled(Authmethod *method) 2270{ 2271 if (method == NULL) 2272 return 0; 2273 /* return false if options indicate this method is disabled */ 2274 if (method->enabled == NULL || *method->enabled == 0) 2275 return 0; 2276 /* return false if batch mode is enabled but method needs interactive mode */ 2277 if (method->batch_flag != NULL && *method->batch_flag != 0) 2278 return 0; 2279 return 1; 2280} 2281 2282static Authmethod * 2283authmethod_lookup(const char *name) 2284{ 2285 Authmethod *method = NULL; 2286 if (name != NULL) 2287 for (method = authmethods; method->name != NULL; method++) 2288 if (strcmp(name, method->name) == 0) 2289 return method; 2290 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2291 return NULL; 2292} 2293 2294/* XXX internal state */ 2295static Authmethod *current = NULL; 2296static char *supported = NULL; 2297static char *preferred = NULL; 2298 2299/* 2300 * Given the authentication method list sent by the server, return the 2301 * next method we should try. If the server initially sends a nil list, 2302 * use a built-in default list. 2303 */ 2304static Authmethod * 2305authmethod_get(char *authlist) 2306{ 2307 char *name = NULL; 2308 u_int next; 2309 2310 /* Use a suitable default if we're passed a nil list. */ 2311 if (authlist == NULL || strlen(authlist) == 0) 2312 authlist = options.preferred_authentications; 2313 2314 if (supported == NULL || strcmp(authlist, supported) != 0) { 2315 debug3("start over, passed a different list %s", authlist); 2316 free(supported); 2317 supported = xstrdup(authlist); 2318 preferred = options.preferred_authentications; 2319 debug3("preferred %s", preferred); 2320 current = NULL; 2321 } else if (current != NULL && authmethod_is_enabled(current)) 2322 return current; 2323 2324 for (;;) { 2325 if ((name = match_list(preferred, supported, &next)) == NULL) { 2326 debug("No more authentication methods to try."); 2327 current = NULL; 2328 return NULL; 2329 } 2330 preferred += next; 2331 debug3("authmethod_lookup %s", name); 2332 debug3("remaining preferred: %s", preferred); 2333 if ((current = authmethod_lookup(name)) != NULL && 2334 authmethod_is_enabled(current)) { 2335 debug3("authmethod_is_enabled %s", name); 2336 debug("Next authentication method: %s", name); 2337 free(name); 2338 return current; 2339 } 2340 free(name); 2341 } 2342} 2343 2344static char * 2345authmethods_get(void) 2346{ 2347 Authmethod *method = NULL; 2348 struct sshbuf *b; 2349 char *list; 2350 int r; 2351 2352 if ((b = sshbuf_new()) == NULL) 2353 fatal_f("sshbuf_new failed"); 2354 for (method = authmethods; method->name != NULL; method++) { 2355 if (authmethod_is_enabled(method)) { 2356 if ((r = sshbuf_putf(b, "%s%s", 2357 sshbuf_len(b) ? "," : "", method->name)) != 0) 2358 fatal_fr(r, "buffer error"); 2359 } 2360 } 2361 if ((list = sshbuf_dup_string(b)) == NULL) 2362 fatal_f("sshbuf_dup_string failed"); 2363 sshbuf_free(b); 2364 return list; 2365} 2366