sshconnect2.c revision 1.1.1.31
1 /* $OpenBSD: sshconnect2.c,v 1.367 2023/08/01 08:15:04 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <limits.h> 36 #include <netdb.h> 37 #include <stdio.h> 38 #include <string.h> 39 #include <stdarg.h> 40 #include <signal.h> 41 #include <pwd.h> 42 #include <unistd.h> 43 #include <vis.h> 44 45 #include "xmalloc.h" 46 #include "ssh.h" 47 #include "ssh2.h" 48 #include "sshbuf.h" 49 #include "packet.h" 50 #include "compat.h" 51 #include "cipher.h" 52 #include "sshkey.h" 53 #include "kex.h" 54 #include "sshconnect.h" 55 #include "authfile.h" 56 #include "dh.h" 57 #include "authfd.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "readconf.h" 61 #include "match.h" 62 #include "dispatch.h" 63 #include "canohost.h" 64 #include "msg.h" 65 #include "pathnames.h" 66 #include "uidswap.h" 67 #include "hostfile.h" 68 #include "ssherr.h" 69 #include "utf8.h" 70 #include "ssh-sk.h" 71 #include "sk-api.h" 72 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 77 /* import */ 78 extern char *client_version_string; 79 extern char *server_version_string; 80 extern Options options; 81 82 /* 83 * SSH2 key exchange 84 */ 85 86 static char *xxx_host; 87 static struct sockaddr *xxx_hostaddr; 88 static const struct ssh_conn_info *xxx_conn_info; 89 90 static int 91 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 92 { 93 int r; 94 95 if ((r = sshkey_check_rsa_length(hostkey, 96 options.required_rsa_size)) != 0) 97 fatal_r(r, "Bad server host key"); 98 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 99 xxx_conn_info) == -1) 100 fatal("Host key verification failed."); 101 return 0; 102 } 103 104 /* Returns the first item from a comma-separated algorithm list */ 105 static char * 106 first_alg(const char *algs) 107 { 108 char *ret, *cp; 109 110 ret = xstrdup(algs); 111 if ((cp = strchr(ret, ',')) != NULL) 112 *cp = '\0'; 113 return ret; 114 } 115 116 static char * 117 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 118 const struct ssh_conn_info *cinfo) 119 { 120 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 121 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 122 size_t maxlen; 123 struct hostkeys *hostkeys = NULL; 124 int ktype; 125 u_int i; 126 127 /* Find all hostkeys for this hostname */ 128 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 129 hostkeys = init_hostkeys(); 130 for (i = 0; i < options.num_user_hostfiles; i++) 131 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 132 for (i = 0; i < options.num_system_hostfiles; i++) { 133 load_hostkeys(hostkeys, hostname, 134 options.system_hostfiles[i], 0); 135 } 136 if (options.known_hosts_command != NULL) { 137 load_hostkeys_command(hostkeys, options.known_hosts_command, 138 "ORDER", cinfo, NULL, host); 139 } 140 /* 141 * If a plain public key exists that matches the type of the best 142 * preference HostkeyAlgorithms, then use the whole list as is. 143 * Note that we ignore whether the best preference algorithm is a 144 * certificate type, as sshconnect.c will downgrade certs to 145 * plain keys if necessary. 146 */ 147 best = first_alg(options.hostkeyalgorithms); 148 if (lookup_key_in_hostkeys_by_type(hostkeys, 149 sshkey_type_plain(sshkey_type_from_name(best)), 150 sshkey_ecdsa_nid_from_name(best), NULL)) { 151 debug3_f("have matching best-preference key type %s, " 152 "using HostkeyAlgorithms verbatim", best); 153 ret = xstrdup(options.hostkeyalgorithms); 154 goto out; 155 } 156 157 /* 158 * Otherwise, prefer the host key algorithms that match known keys 159 * while keeping the ordering of HostkeyAlgorithms as much as possible. 160 */ 161 oavail = avail = xstrdup(options.hostkeyalgorithms); 162 maxlen = strlen(avail) + 1; 163 first = xmalloc(maxlen); 164 last = xmalloc(maxlen); 165 *first = *last = '\0'; 166 167 #define ALG_APPEND(to, from) \ 168 do { \ 169 if (*to != '\0') \ 170 strlcat(to, ",", maxlen); \ 171 strlcat(to, from, maxlen); \ 172 } while (0) 173 174 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 175 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 176 fatal_f("unknown alg %s", alg); 177 /* 178 * If we have a @cert-authority marker in known_hosts then 179 * prefer all certificate algorithms. 180 */ 181 if (sshkey_type_is_cert(ktype) && 182 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 183 ALG_APPEND(first, alg); 184 continue; 185 } 186 /* If the key appears in known_hosts then prefer it */ 187 if (lookup_key_in_hostkeys_by_type(hostkeys, 188 sshkey_type_plain(ktype), 189 sshkey_ecdsa_nid_from_name(alg), NULL)) { 190 ALG_APPEND(first, alg); 191 continue; 192 } 193 /* Otherwise, put it last */ 194 ALG_APPEND(last, alg); 195 } 196 #undef ALG_APPEND 197 xasprintf(&ret, "%s%s%s", first, 198 (*first == '\0' || *last == '\0') ? "" : ",", last); 199 if (*first != '\0') 200 debug3_f("prefer hostkeyalgs: %s", first); 201 else 202 debug3_f("no algorithms matched; accept original"); 203 out: 204 free(best); 205 free(first); 206 free(last); 207 free(hostname); 208 free(oavail); 209 free_hostkeys(hostkeys); 210 211 return ret; 212 } 213 214 void 215 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 216 const struct ssh_conn_info *cinfo) 217 { 218 char *myproposal[PROPOSAL_MAX]; 219 char *s, *all_key, *hkalgs = NULL; 220 int r, use_known_hosts_order = 0; 221 222 xxx_host = host; 223 xxx_hostaddr = hostaddr; 224 xxx_conn_info = cinfo; 225 226 if (options.rekey_limit || options.rekey_interval) 227 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 228 options.rekey_interval); 229 230 /* 231 * If the user has not specified HostkeyAlgorithms, or has only 232 * appended or removed algorithms from that list then prefer algorithms 233 * that are in the list that are supported by known_hosts keys. 234 */ 235 if (options.hostkeyalgorithms == NULL || 236 options.hostkeyalgorithms[0] == '-' || 237 options.hostkeyalgorithms[0] == '+') 238 use_known_hosts_order = 1; 239 240 /* Expand or fill in HostkeyAlgorithms */ 241 all_key = sshkey_alg_list(0, 0, 1, ','); 242 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 243 kex_default_pk_alg(), all_key)) != 0) 244 fatal_fr(r, "kex_assemble_namelist"); 245 free(all_key); 246 247 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 248 fatal_f("kex_names_cat"); 249 250 if (use_known_hosts_order) 251 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 252 253 kex_proposal_populate_entries(ssh, myproposal, s, options.ciphers, 254 options.macs, compression_alg_list(options.compression), 255 hkalgs ? hkalgs : options.hostkeyalgorithms); 256 257 free(hkalgs); 258 259 /* start key exchange */ 260 if ((r = kex_setup(ssh, myproposal)) != 0) 261 fatal_r(r, "kex_setup"); 262 #ifdef WITH_OPENSSL 263 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 264 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 265 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 266 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 267 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 268 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 269 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 270 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 271 #endif 272 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 273 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 274 ssh->kex->verify_host_key=&verify_host_key_callback; 275 276 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 277 278 /* remove ext-info from the KEX proposals for rekeying */ 279 free(myproposal[PROPOSAL_KEX_ALGS]); 280 myproposal[PROPOSAL_KEX_ALGS] = 281 compat_kex_proposal(ssh, options.kex_algorithms); 282 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 283 fatal_r(r, "kex_prop2buf"); 284 285 #ifdef DEBUG_KEXDH 286 /* send 1st encrypted/maced/compressed message */ 287 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 288 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 289 (r = sshpkt_send(ssh)) != 0 || 290 (r = ssh_packet_write_wait(ssh)) != 0) 291 fatal_fr(r, "send packet"); 292 #endif 293 kex_proposal_free_entries(myproposal); 294 } 295 296 /* 297 * Authenticate user 298 */ 299 300 typedef struct cauthctxt Authctxt; 301 typedef struct cauthmethod Authmethod; 302 typedef struct identity Identity; 303 typedef struct idlist Idlist; 304 305 struct identity { 306 TAILQ_ENTRY(identity) next; 307 int agent_fd; /* >=0 if agent supports key */ 308 struct sshkey *key; /* public/private key */ 309 char *filename; /* comment for agent-only keys */ 310 int tried; 311 int isprivate; /* key points to the private key */ 312 int userprovided; 313 }; 314 TAILQ_HEAD(idlist, identity); 315 316 struct cauthctxt { 317 const char *server_user; 318 const char *local_user; 319 const char *host; 320 const char *service; 321 struct cauthmethod *method; 322 sig_atomic_t success; 323 char *authlist; 324 #ifdef GSSAPI 325 /* gssapi */ 326 gss_OID_set gss_supported_mechs; 327 u_int mech_tried; 328 #endif 329 /* pubkey */ 330 struct idlist keys; 331 int agent_fd; 332 /* hostbased */ 333 Sensitive *sensitive; 334 char *oktypes, *ktypes; 335 const char *active_ktype; 336 /* kbd-interactive */ 337 int info_req_seen; 338 int attempt_kbdint; 339 /* password */ 340 int attempt_passwd; 341 /* generic */ 342 void *methoddata; 343 }; 344 345 struct cauthmethod { 346 char *name; /* string to compare against server's list */ 347 int (*userauth)(struct ssh *ssh); 348 void (*cleanup)(struct ssh *ssh); 349 int *enabled; /* flag in option struct that enables method */ 350 int *batch_flag; /* flag in option struct that disables method */ 351 }; 352 353 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 354 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 355 static int input_userauth_success(int, u_int32_t, struct ssh *); 356 static int input_userauth_failure(int, u_int32_t, struct ssh *); 357 static int input_userauth_banner(int, u_int32_t, struct ssh *); 358 static int input_userauth_error(int, u_int32_t, struct ssh *); 359 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 360 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 361 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 362 363 static int userauth_none(struct ssh *); 364 static int userauth_pubkey(struct ssh *); 365 static int userauth_passwd(struct ssh *); 366 static int userauth_kbdint(struct ssh *); 367 static int userauth_hostbased(struct ssh *); 368 369 #ifdef GSSAPI 370 static int userauth_gssapi(struct ssh *); 371 static void userauth_gssapi_cleanup(struct ssh *); 372 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 373 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 374 static int input_gssapi_error(int, u_int32_t, struct ssh *); 375 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 376 #endif 377 378 void userauth(struct ssh *, char *); 379 380 static void pubkey_cleanup(struct ssh *); 381 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 382 static void pubkey_prepare(struct ssh *, Authctxt *); 383 static void pubkey_reset(Authctxt *); 384 static struct sshkey *load_identity_file(Identity *); 385 386 static Authmethod *authmethod_get(char *authlist); 387 static Authmethod *authmethod_lookup(const char *name); 388 static char *authmethods_get(void); 389 390 Authmethod authmethods[] = { 391 #ifdef GSSAPI 392 {"gssapi-with-mic", 393 userauth_gssapi, 394 userauth_gssapi_cleanup, 395 &options.gss_authentication, 396 NULL}, 397 #endif 398 {"hostbased", 399 userauth_hostbased, 400 NULL, 401 &options.hostbased_authentication, 402 NULL}, 403 {"publickey", 404 userauth_pubkey, 405 NULL, 406 &options.pubkey_authentication, 407 NULL}, 408 {"keyboard-interactive", 409 userauth_kbdint, 410 NULL, 411 &options.kbd_interactive_authentication, 412 &options.batch_mode}, 413 {"password", 414 userauth_passwd, 415 NULL, 416 &options.password_authentication, 417 &options.batch_mode}, 418 {"none", 419 userauth_none, 420 NULL, 421 NULL, 422 NULL}, 423 {NULL, NULL, NULL, NULL, NULL} 424 }; 425 426 void 427 ssh_userauth2(struct ssh *ssh, const char *local_user, 428 const char *server_user, char *host, Sensitive *sensitive) 429 { 430 Authctxt authctxt; 431 int r; 432 433 if (options.preferred_authentications == NULL) 434 options.preferred_authentications = authmethods_get(); 435 436 /* setup authentication context */ 437 memset(&authctxt, 0, sizeof(authctxt)); 438 authctxt.server_user = server_user; 439 authctxt.local_user = local_user; 440 authctxt.host = host; 441 authctxt.service = "ssh-connection"; /* service name */ 442 authctxt.success = 0; 443 authctxt.method = authmethod_lookup("none"); 444 authctxt.authlist = NULL; 445 authctxt.methoddata = NULL; 446 authctxt.sensitive = sensitive; 447 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 448 authctxt.info_req_seen = 0; 449 authctxt.attempt_kbdint = 0; 450 authctxt.attempt_passwd = 0; 451 #if GSSAPI 452 authctxt.gss_supported_mechs = NULL; 453 authctxt.mech_tried = 0; 454 #endif 455 authctxt.agent_fd = -1; 456 pubkey_prepare(ssh, &authctxt); 457 if (authctxt.method == NULL) { 458 fatal_f("internal error: cannot send userauth none request"); 459 } 460 461 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 462 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 463 (r = sshpkt_send(ssh)) != 0) 464 fatal_fr(r, "send packet"); 465 466 ssh->authctxt = &authctxt; 467 ssh_dispatch_init(ssh, &input_userauth_error); 468 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 469 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 470 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 471 pubkey_cleanup(ssh); 472 ssh->authctxt = NULL; 473 474 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 475 476 if (!authctxt.success) 477 fatal("Authentication failed."); 478 if (ssh_packet_connection_is_on_socket(ssh)) { 479 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 480 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 481 authctxt.method->name); 482 } else { 483 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 484 authctxt.method->name); 485 } 486 } 487 488 static int 489 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 490 { 491 int r; 492 493 if (ssh_packet_remaining(ssh) > 0) { 494 char *reply; 495 496 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 497 goto out; 498 debug2("service_accept: %s", reply); 499 free(reply); 500 } else { 501 debug2("buggy server: service_accept w/o service"); 502 } 503 if ((r = sshpkt_get_end(ssh)) != 0) 504 goto out; 505 debug("SSH2_MSG_SERVICE_ACCEPT received"); 506 507 /* initial userauth request */ 508 userauth_none(ssh); 509 510 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 511 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 512 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 513 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 514 r = 0; 515 out: 516 return r; 517 } 518 519 static int 520 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 521 { 522 return kex_input_ext_info(type, seqnr, ssh); 523 } 524 525 void 526 userauth(struct ssh *ssh, char *authlist) 527 { 528 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 529 530 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 531 authctxt->method->cleanup(ssh); 532 533 free(authctxt->methoddata); 534 authctxt->methoddata = NULL; 535 if (authlist == NULL) { 536 authlist = authctxt->authlist; 537 } else { 538 free(authctxt->authlist); 539 authctxt->authlist = authlist; 540 } 541 for (;;) { 542 Authmethod *method = authmethod_get(authlist); 543 if (method == NULL) 544 fatal("%s@%s: Permission denied (%s).", 545 authctxt->server_user, authctxt->host, authlist); 546 authctxt->method = method; 547 548 /* reset the per method handler */ 549 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 550 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 551 552 /* and try new method */ 553 if (method->userauth(ssh) != 0) { 554 debug2("we sent a %s packet, wait for reply", method->name); 555 break; 556 } else { 557 debug2("we did not send a packet, disable method"); 558 method->enabled = NULL; 559 } 560 } 561 } 562 563 static int 564 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 565 { 566 fatal_f("bad message during authentication: type %d", type); 567 return 0; 568 } 569 570 static int 571 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 572 { 573 char *msg = NULL; 574 size_t len; 575 int r; 576 577 debug3_f("entering"); 578 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 579 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 580 goto out; 581 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 582 fmprintf(stderr, "%s", msg); 583 r = 0; 584 out: 585 free(msg); 586 return r; 587 } 588 589 static int 590 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 591 { 592 Authctxt *authctxt = ssh->authctxt; 593 594 if (authctxt == NULL) 595 fatal_f("no authentication context"); 596 free(authctxt->authlist); 597 authctxt->authlist = NULL; 598 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 599 authctxt->method->cleanup(ssh); 600 free(authctxt->methoddata); 601 authctxt->methoddata = NULL; 602 authctxt->success = 1; /* break out */ 603 return 0; 604 } 605 606 #if 0 607 static int 608 input_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 620 621 static int 622 input_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 */ 655 static char * 656 format_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 } 680 681 static int 682 input_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 752 static int 753 userauth_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 } 807 808 static void 809 userauth_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 free(authctxt->gss_supported_mechs); 818 authctxt->gss_supported_mechs = NULL; 819 } 820 821 static OM_uint32 822 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 823 { 824 Authctxt *authctxt = ssh->authctxt; 825 Gssctxt *gssctxt = authctxt->methoddata; 826 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 827 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 828 gss_buffer_desc gssbuf; 829 OM_uint32 status, ms, flags; 830 int r; 831 832 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 833 recv_tok, &send_tok, &flags); 834 835 if (send_tok.length > 0) { 836 u_char type = GSS_ERROR(status) ? 837 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 838 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 839 840 if ((r = sshpkt_start(ssh, type)) != 0 || 841 (r = sshpkt_put_string(ssh, send_tok.value, 842 send_tok.length)) != 0 || 843 (r = sshpkt_send(ssh)) != 0) 844 fatal_fr(r, "send %u packet", type); 845 846 gss_release_buffer(&ms, &send_tok); 847 } 848 849 if (status == GSS_S_COMPLETE) { 850 /* send either complete or MIC, depending on mechanism */ 851 if (!(flags & GSS_C_INTEG_FLAG)) { 852 if ((r = sshpkt_start(ssh, 853 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 854 (r = sshpkt_send(ssh)) != 0) 855 fatal_fr(r, "send completion"); 856 } else { 857 struct sshbuf *b; 858 859 if ((b = sshbuf_new()) == NULL) 860 fatal_f("sshbuf_new failed"); 861 ssh_gssapi_buildmic(b, authctxt->server_user, 862 authctxt->service, "gssapi-with-mic", 863 ssh->kex->session_id); 864 865 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 866 fatal_f("sshbuf_mutable_ptr failed"); 867 gssbuf.length = sshbuf_len(b); 868 869 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 870 871 if (!GSS_ERROR(status)) { 872 if ((r = sshpkt_start(ssh, 873 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 874 (r = sshpkt_put_string(ssh, mic.value, 875 mic.length)) != 0 || 876 (r = sshpkt_send(ssh)) != 0) 877 fatal_fr(r, "send MIC"); 878 } 879 880 sshbuf_free(b); 881 gss_release_buffer(&ms, &mic); 882 } 883 } 884 885 return status; 886 } 887 888 static int 889 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 890 { 891 Authctxt *authctxt = ssh->authctxt; 892 Gssctxt *gssctxt; 893 size_t oidlen; 894 u_char *oidv = NULL; 895 int r; 896 897 if (authctxt == NULL) 898 fatal("input_gssapi_response: no authentication context"); 899 gssctxt = authctxt->methoddata; 900 901 /* Setup our OID */ 902 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 903 goto done; 904 905 if (oidlen <= 2 || 906 oidv[0] != SSH_GSS_OIDTYPE || 907 oidv[1] != oidlen - 2) { 908 debug("Badly encoded mechanism OID received"); 909 userauth(ssh, NULL); 910 goto ok; 911 } 912 913 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 914 fatal("Server returned different OID than expected"); 915 916 if ((r = sshpkt_get_end(ssh)) != 0) 917 goto done; 918 919 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 920 /* Start again with next method on list */ 921 debug("Trying to start again"); 922 userauth(ssh, NULL); 923 goto ok; 924 } 925 ok: 926 r = 0; 927 done: 928 free(oidv); 929 return r; 930 } 931 932 static int 933 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 934 { 935 Authctxt *authctxt = ssh->authctxt; 936 gss_buffer_desc recv_tok; 937 u_char *p = NULL; 938 size_t len; 939 OM_uint32 status; 940 int r; 941 942 if (authctxt == NULL) 943 fatal("input_gssapi_response: no authentication context"); 944 945 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 946 (r = sshpkt_get_end(ssh)) != 0) 947 goto out; 948 949 recv_tok.value = p; 950 recv_tok.length = len; 951 status = process_gssapi_token(ssh, &recv_tok); 952 953 /* Start again with the next method in the list */ 954 if (GSS_ERROR(status)) { 955 userauth(ssh, NULL); 956 /* ok */ 957 } 958 r = 0; 959 out: 960 free(p); 961 return r; 962 } 963 964 static int 965 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 966 { 967 Authctxt *authctxt = ssh->authctxt; 968 Gssctxt *gssctxt; 969 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 970 gss_buffer_desc recv_tok; 971 OM_uint32 ms; 972 u_char *p = NULL; 973 size_t len; 974 int r; 975 976 if (authctxt == NULL) 977 fatal("input_gssapi_response: no authentication context"); 978 gssctxt = authctxt->methoddata; 979 980 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 981 (r = sshpkt_get_end(ssh)) != 0) { 982 free(p); 983 return r; 984 } 985 986 /* Stick it into GSSAPI and see what it says */ 987 recv_tok.value = p; 988 recv_tok.length = len; 989 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 990 &recv_tok, &send_tok, NULL); 991 free(p); 992 gss_release_buffer(&ms, &send_tok); 993 994 /* Server will be returning a failed packet after this one */ 995 return 0; 996 } 997 998 static int 999 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1000 { 1001 char *msg = NULL; 1002 char *lang = NULL; 1003 int r; 1004 1005 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1006 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1007 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1008 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1009 goto out; 1010 r = sshpkt_get_end(ssh); 1011 debug("Server GSSAPI Error:\n%s", msg); 1012 out: 1013 free(msg); 1014 free(lang); 1015 return r; 1016 } 1017 #endif /* GSSAPI */ 1018 1019 static int 1020 userauth_none(struct ssh *ssh) 1021 { 1022 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1023 int r; 1024 1025 /* initial userauth request */ 1026 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1027 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1028 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1029 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1030 (r = sshpkt_send(ssh)) != 0) 1031 fatal_fr(r, "send packet"); 1032 return 1; 1033 } 1034 1035 static int 1036 userauth_passwd(struct ssh *ssh) 1037 { 1038 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1039 char *password, *prompt = NULL; 1040 const char *host = options.host_key_alias ? options.host_key_alias : 1041 authctxt->host; 1042 int r; 1043 1044 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1045 return 0; 1046 1047 if (authctxt->attempt_passwd != 1) 1048 error("Permission denied, please try again."); 1049 1050 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1051 password = read_passphrase(prompt, 0); 1052 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1053 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1056 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1057 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1058 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1059 (r = sshpkt_send(ssh)) != 0) 1060 fatal_fr(r, "send packet"); 1061 1062 free(prompt); 1063 if (password != NULL) 1064 freezero(password, strlen(password)); 1065 1066 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1067 &input_userauth_passwd_changereq); 1068 1069 return 1; 1070 } 1071 1072 /* 1073 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1074 */ 1075 static int 1076 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1077 { 1078 Authctxt *authctxt = ssh->authctxt; 1079 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1080 char prompt[256]; 1081 const char *host; 1082 int r; 1083 1084 debug2("input_userauth_passwd_changereq"); 1085 1086 if (authctxt == NULL) 1087 fatal("input_userauth_passwd_changereq: " 1088 "no authentication context"); 1089 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1090 1091 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1092 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1093 goto out; 1094 if (strlen(info) > 0) 1095 logit("%s", info); 1096 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1097 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1098 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1099 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1100 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1101 goto out; 1102 1103 snprintf(prompt, sizeof(prompt), 1104 "Enter %.30s@%.128s's old password: ", 1105 authctxt->server_user, host); 1106 password = read_passphrase(prompt, 0); 1107 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1108 goto out; 1109 1110 freezero(password, strlen(password)); 1111 password = NULL; 1112 while (password == NULL) { 1113 snprintf(prompt, sizeof(prompt), 1114 "Enter %.30s@%.128s's new password: ", 1115 authctxt->server_user, host); 1116 password = read_passphrase(prompt, RP_ALLOW_EOF); 1117 if (password == NULL) { 1118 /* bail out */ 1119 r = 0; 1120 goto out; 1121 } 1122 snprintf(prompt, sizeof(prompt), 1123 "Retype %.30s@%.128s's new password: ", 1124 authctxt->server_user, host); 1125 retype = read_passphrase(prompt, 0); 1126 if (strcmp(password, retype) != 0) { 1127 freezero(password, strlen(password)); 1128 logit("Mismatch; try again, EOF to quit."); 1129 password = NULL; 1130 } 1131 freezero(retype, strlen(retype)); 1132 } 1133 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1134 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1135 (r = sshpkt_send(ssh)) != 0) 1136 goto out; 1137 1138 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1139 &input_userauth_passwd_changereq); 1140 r = 0; 1141 out: 1142 if (password) 1143 freezero(password, strlen(password)); 1144 free(info); 1145 free(lang); 1146 return r; 1147 } 1148 1149 /* 1150 * Select an algorithm for publickey signatures. 1151 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1152 * 1153 * Call with ssh==NULL to ignore server-sig-algs extension list and 1154 * only attempt with the key's base signature type. 1155 */ 1156 static char * 1157 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1158 { 1159 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1160 const char *server_sig_algs; 1161 1162 /* 1163 * The signature algorithm will only differ from the key algorithm 1164 * for RSA keys/certs and when the server advertises support for 1165 * newer (SHA2) algorithms. 1166 */ 1167 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1168 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1169 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1170 /* Filter base key signature alg against our configuration */ 1171 return match_list(sshkey_ssh_name(key), 1172 options.pubkey_accepted_algos, NULL); 1173 } 1174 1175 /* 1176 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1177 * fails to advertise it via SSH2_MSG_EXT_INFO. 1178 */ 1179 server_sig_algs = ssh->kex->server_sig_algs; 1180 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1181 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1182 1183 /* 1184 * For RSA keys/certs, since these might have a different sig type: 1185 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1186 * that also appears in the supported signature algorithms list from 1187 * the server. 1188 */ 1189 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1190 while ((cp = strsep(&allowed, ",")) != NULL) { 1191 if (sshkey_type_from_name(cp) != key->type) 1192 continue; 1193 tmp = match_list(sshkey_sigalg_by_name(cp), 1194 server_sig_algs, NULL); 1195 if (tmp != NULL) 1196 alg = xstrdup(cp); 1197 free(tmp); 1198 if (alg != NULL) 1199 break; 1200 } 1201 free(oallowed); 1202 return alg; 1203 } 1204 1205 static int 1206 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1207 const u_char *data, size_t datalen, u_int compat, const char *alg) 1208 { 1209 struct sshkey *sign_key = NULL, *prv = NULL; 1210 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1211 struct notifier_ctx *notifier = NULL; 1212 char *fp = NULL, *pin = NULL, *prompt = NULL; 1213 1214 *sigp = NULL; 1215 *lenp = 0; 1216 1217 /* The agent supports this key. */ 1218 if (id->key != NULL && id->agent_fd != -1) { 1219 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1220 data, datalen, alg, compat); 1221 } 1222 1223 /* 1224 * We have already loaded the private key or the private key is 1225 * stored in external hardware. 1226 */ 1227 if (id->key != NULL && 1228 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1229 sign_key = id->key; 1230 is_agent = 1; 1231 } else { 1232 /* Load the private key from the file. */ 1233 if ((prv = load_identity_file(id)) == NULL) 1234 return SSH_ERR_KEY_NOT_FOUND; 1235 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1236 error_f("private key %s contents do not match public", 1237 id->filename); 1238 r = SSH_ERR_KEY_NOT_FOUND; 1239 goto out; 1240 } 1241 sign_key = prv; 1242 } 1243 retry_pin: 1244 /* Prompt for touch for non-agent FIDO keys that request UP */ 1245 if (!is_agent && sshkey_is_sk(sign_key) && 1246 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1247 /* XXX should batch mode just skip these? */ 1248 if ((fp = sshkey_fingerprint(sign_key, 1249 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1250 fatal_f("fingerprint failed"); 1251 notifier = notify_start(options.batch_mode, 1252 "Confirm user presence for key %s %s", 1253 sshkey_type(sign_key), fp); 1254 free(fp); 1255 } 1256 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1257 alg, options.sk_provider, pin, compat)) != 0) { 1258 debug_fr(r, "sshkey_sign"); 1259 if (!retried && pin == NULL && !is_agent && 1260 sshkey_is_sk(sign_key) && 1261 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1262 notify_complete(notifier, NULL); 1263 notifier = NULL; 1264 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1265 sshkey_type(sign_key), id->filename); 1266 pin = read_passphrase(prompt, 0); 1267 retried = 1; 1268 goto retry_pin; 1269 } 1270 goto out; 1271 } 1272 1273 /* 1274 * PKCS#11 tokens may not support all signature algorithms, 1275 * so check what we get back. 1276 */ 1277 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1278 debug_fr(r, "sshkey_check_sigtype"); 1279 goto out; 1280 } 1281 /* success */ 1282 r = 0; 1283 out: 1284 free(prompt); 1285 if (pin != NULL) 1286 freezero(pin, strlen(pin)); 1287 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1288 sshkey_free(prv); 1289 return r; 1290 } 1291 1292 static int 1293 id_filename_matches(Identity *id, Identity *private_id) 1294 { 1295 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1296 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1297 size_t i, slen; 1298 1299 if (strcmp(id->filename, private_id->filename) == 0) 1300 return 1; 1301 for (i = 0; suffixes[i]; i++) { 1302 slen = strlen(suffixes[i]); 1303 if (len > slen && plen == len - slen && 1304 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1305 memcmp(id->filename, private_id->filename, plen) == 0) 1306 return 1; 1307 } 1308 return 0; 1309 } 1310 1311 static int 1312 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1313 { 1314 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1315 struct sshbuf *b = NULL; 1316 Identity *private_id, *sign_id = NULL; 1317 u_char *signature = NULL; 1318 size_t slen = 0, skip = 0; 1319 int r, fallback_sigtype, sent = 0; 1320 char *alg = NULL, *fp = NULL; 1321 const char *loc = "", *method = "publickey"; 1322 int hostbound = 0; 1323 1324 /* prefer host-bound pubkey signatures if supported by server */ 1325 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1326 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1327 hostbound = 1; 1328 method = "publickey-hostbound-v00 (at) openssh.com"; 1329 } 1330 1331 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1332 SSH_FP_DEFAULT)) == NULL) 1333 return 0; 1334 1335 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1336 1337 /* 1338 * If the key is an certificate, try to find a matching private key 1339 * and use it to complete the signature. 1340 * If no such private key exists, fall back to trying the certificate 1341 * key itself in case it has a private half already loaded. 1342 * This will try to set sign_id to the private key that will perform 1343 * the signature. 1344 */ 1345 if (sshkey_is_cert(id->key)) { 1346 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1347 if (sshkey_equal_public(id->key, private_id->key) && 1348 id->key->type != private_id->key->type) { 1349 sign_id = private_id; 1350 break; 1351 } 1352 } 1353 /* 1354 * Exact key matches are preferred, but also allow 1355 * filename matches for non-PKCS#11/agent keys that 1356 * didn't load public keys. This supports the case 1357 * of keeping just a private key file and public 1358 * certificate on disk. 1359 */ 1360 if (sign_id == NULL && 1361 !id->isprivate && id->agent_fd == -1 && 1362 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1363 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1364 if (private_id->key == NULL && 1365 id_filename_matches(id, private_id)) { 1366 sign_id = private_id; 1367 break; 1368 } 1369 } 1370 } 1371 if (sign_id != NULL) { 1372 debug2_f("using private key \"%s\"%s for " 1373 "certificate", sign_id->filename, 1374 sign_id->agent_fd != -1 ? " from agent" : ""); 1375 } else { 1376 debug_f("no separate private key for certificate " 1377 "\"%s\"", id->filename); 1378 } 1379 } 1380 1381 /* 1382 * If the above didn't select another identity to do the signing 1383 * then default to the one we started with. 1384 */ 1385 if (sign_id == NULL) 1386 sign_id = id; 1387 1388 /* assemble and sign data */ 1389 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1390 free(alg); 1391 slen = 0; 1392 signature = NULL; 1393 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1394 id->key)) == NULL) { 1395 error_f("no mutual signature supported"); 1396 goto out; 1397 } 1398 debug3_f("signing using %s %s", alg, fp); 1399 1400 sshbuf_free(b); 1401 if ((b = sshbuf_new()) == NULL) 1402 fatal_f("sshbuf_new failed"); 1403 if (ssh->compat & SSH_OLD_SESSIONID) { 1404 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1405 fatal_fr(r, "sshbuf_putb"); 1406 } else { 1407 if ((r = sshbuf_put_stringb(b, 1408 ssh->kex->session_id)) != 0) 1409 fatal_fr(r, "sshbuf_put_stringb"); 1410 } 1411 skip = sshbuf_len(b); 1412 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1413 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1414 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1415 (r = sshbuf_put_cstring(b, method)) != 0 || 1416 (r = sshbuf_put_u8(b, 1)) != 0 || 1417 (r = sshbuf_put_cstring(b, alg)) != 0 || 1418 (r = sshkey_puts(id->key, b)) != 0) { 1419 fatal_fr(r, "assemble signed data"); 1420 } 1421 if (hostbound) { 1422 if (ssh->kex->initial_hostkey == NULL) { 1423 fatal_f("internal error: initial hostkey " 1424 "not recorded"); 1425 } 1426 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1427 fatal_fr(r, "assemble %s hostkey", method); 1428 } 1429 /* generate signature */ 1430 r = identity_sign(sign_id, &signature, &slen, 1431 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1432 if (r == 0) 1433 break; 1434 else if (r == SSH_ERR_KEY_NOT_FOUND) 1435 goto out; /* soft failure */ 1436 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1437 !fallback_sigtype) { 1438 if (sign_id->agent_fd != -1) 1439 loc = "agent "; 1440 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1441 loc = "token "; 1442 logit("%skey %s %s returned incorrect signature type", 1443 loc, sshkey_type(id->key), fp); 1444 continue; 1445 } 1446 error_fr(r, "signing failed for %s \"%s\"%s", 1447 sshkey_type(sign_id->key), sign_id->filename, 1448 id->agent_fd != -1 ? " from agent" : ""); 1449 goto out; 1450 } 1451 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1452 fatal_f("no signature"); 1453 1454 /* append signature */ 1455 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1456 fatal_fr(r, "append signature"); 1457 1458 #ifdef DEBUG_PK 1459 sshbuf_dump(b, stderr); 1460 #endif 1461 /* skip session id and packet type */ 1462 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1463 fatal_fr(r, "consume"); 1464 1465 /* put remaining data from buffer into packet */ 1466 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1467 (r = sshpkt_putb(ssh, b)) != 0 || 1468 (r = sshpkt_send(ssh)) != 0) 1469 fatal_fr(r, "enqueue request"); 1470 1471 /* success */ 1472 sent = 1; 1473 1474 out: 1475 free(fp); 1476 free(alg); 1477 sshbuf_free(b); 1478 freezero(signature, slen); 1479 return sent; 1480 } 1481 1482 static int 1483 send_pubkey_test(struct ssh *ssh, Identity *id) 1484 { 1485 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1486 u_char *blob = NULL; 1487 char *alg = NULL; 1488 size_t bloblen; 1489 u_int have_sig = 0; 1490 int sent = 0, r; 1491 1492 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1493 debug_f("no mutual signature algorithm"); 1494 goto out; 1495 } 1496 1497 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1498 /* we cannot handle this key */ 1499 debug3_f("cannot handle key"); 1500 goto out; 1501 } 1502 /* register callback for USERAUTH_PK_OK message */ 1503 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1504 1505 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1506 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1507 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1508 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1509 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1510 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1511 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1512 (r = sshpkt_send(ssh)) != 0) 1513 fatal_fr(r, "send packet"); 1514 sent = 1; 1515 1516 out: 1517 free(alg); 1518 free(blob); 1519 return sent; 1520 } 1521 1522 static struct sshkey * 1523 load_identity_file(Identity *id) 1524 { 1525 struct sshkey *private = NULL; 1526 char prompt[300], *passphrase, *comment; 1527 int r, quit = 0, i; 1528 struct stat st; 1529 1530 if (stat(id->filename, &st) == -1) { 1531 do_log2(id->userprovided ? 1532 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1533 "no such identity: %s: %s", id->filename, strerror(errno)); 1534 return NULL; 1535 } 1536 snprintf(prompt, sizeof prompt, 1537 "Enter passphrase for key '%.100s': ", id->filename); 1538 for (i = 0; i <= options.number_of_password_prompts; i++) { 1539 if (i == 0) 1540 passphrase = ""; 1541 else { 1542 passphrase = read_passphrase(prompt, 0); 1543 if (*passphrase == '\0') { 1544 debug2("no passphrase given, try next key"); 1545 free(passphrase); 1546 break; 1547 } 1548 } 1549 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1550 passphrase, &private, &comment))) { 1551 case 0: 1552 break; 1553 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1554 if (options.batch_mode) { 1555 quit = 1; 1556 break; 1557 } 1558 if (i != 0) 1559 debug2("bad passphrase given, try again..."); 1560 break; 1561 case SSH_ERR_SYSTEM_ERROR: 1562 if (errno == ENOENT) { 1563 debug2_r(r, "Load key \"%s\"", id->filename); 1564 quit = 1; 1565 break; 1566 } 1567 /* FALLTHROUGH */ 1568 default: 1569 error_r(r, "Load key \"%s\"", id->filename); 1570 quit = 1; 1571 break; 1572 } 1573 if (private != NULL && sshkey_is_sk(private) && 1574 options.sk_provider == NULL) { 1575 debug("key \"%s\" is an authenticator-hosted key, " 1576 "but no provider specified", id->filename); 1577 sshkey_free(private); 1578 private = NULL; 1579 quit = 1; 1580 } 1581 if (!quit && (r = sshkey_check_rsa_length(private, 1582 options.required_rsa_size)) != 0) { 1583 debug_fr(r, "Skipping key %s", id->filename); 1584 sshkey_free(private); 1585 private = NULL; 1586 quit = 1; 1587 } 1588 if (!quit && private != NULL && id->agent_fd == -1 && 1589 !(id->key && id->isprivate)) 1590 maybe_add_key_to_agent(id->filename, private, comment, 1591 passphrase); 1592 if (i > 0) 1593 freezero(passphrase, strlen(passphrase)); 1594 free(comment); 1595 if (private != NULL || quit) 1596 break; 1597 } 1598 return private; 1599 } 1600 1601 static int 1602 key_type_allowed_by_config(struct sshkey *key) 1603 { 1604 if (match_pattern_list(sshkey_ssh_name(key), 1605 options.pubkey_accepted_algos, 0) == 1) 1606 return 1; 1607 1608 /* RSA keys/certs might be allowed by alternate signature types */ 1609 switch (key->type) { 1610 case KEY_RSA: 1611 if (match_pattern_list("rsa-sha2-512", 1612 options.pubkey_accepted_algos, 0) == 1) 1613 return 1; 1614 if (match_pattern_list("rsa-sha2-256", 1615 options.pubkey_accepted_algos, 0) == 1) 1616 return 1; 1617 break; 1618 case KEY_RSA_CERT: 1619 if (match_pattern_list("rsa-sha2-512-cert-v01 (at) openssh.com", 1620 options.pubkey_accepted_algos, 0) == 1) 1621 return 1; 1622 if (match_pattern_list("rsa-sha2-256-cert-v01 (at) openssh.com", 1623 options.pubkey_accepted_algos, 0) == 1) 1624 return 1; 1625 break; 1626 } 1627 return 0; 1628 } 1629 1630 /* obtain a list of keys from the agent */ 1631 static int 1632 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1633 struct ssh_identitylist **idlistp) 1634 { 1635 int r, agent_fd; 1636 struct ssh_identitylist *idlist; 1637 1638 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1639 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1640 debug_fr(r, "ssh_get_authentication_socket"); 1641 return r; 1642 } 1643 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1644 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1645 debug_f("bound agent to hostkey"); 1646 else 1647 debug2_fr(r, "ssh_agent_bind_hostkey"); 1648 1649 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1650 debug_fr(r, "ssh_fetch_identitylist"); 1651 close(agent_fd); 1652 return r; 1653 } 1654 /* success */ 1655 *agent_fdp = agent_fd; 1656 *idlistp = idlist; 1657 debug_f("agent returned %zu keys", idlist->nkeys); 1658 return 0; 1659 } 1660 1661 /* 1662 * try keys in the following order: 1663 * 1. certificates listed in the config file 1664 * 2. other input certificates 1665 * 3. agent keys that are found in the config file 1666 * 4. other agent keys 1667 * 5. keys that are only listed in the config file 1668 */ 1669 static void 1670 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1671 { 1672 struct identity *id, *id2, *tmp; 1673 struct idlist agent, files, *preferred; 1674 struct sshkey *key; 1675 int agent_fd = -1, i, r, found; 1676 size_t j; 1677 struct ssh_identitylist *idlist; 1678 char *ident; 1679 1680 TAILQ_INIT(&agent); /* keys from the agent */ 1681 TAILQ_INIT(&files); /* keys from the config file */ 1682 preferred = &authctxt->keys; 1683 TAILQ_INIT(preferred); /* preferred order of keys */ 1684 1685 /* list of keys stored in the filesystem and PKCS#11 */ 1686 for (i = 0; i < options.num_identity_files; i++) { 1687 key = options.identity_keys[i]; 1688 if (key && key->cert && 1689 key->cert->type != SSH2_CERT_TYPE_USER) { 1690 debug_f("ignoring certificate %s: not a user " 1691 "certificate", options.identity_files[i]); 1692 continue; 1693 } 1694 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1695 debug_f("ignoring authenticator-hosted key %s as no " 1696 "SecurityKeyProvider has been specified", 1697 options.identity_files[i]); 1698 continue; 1699 } 1700 options.identity_keys[i] = NULL; 1701 id = xcalloc(1, sizeof(*id)); 1702 id->agent_fd = -1; 1703 id->key = key; 1704 id->filename = xstrdup(options.identity_files[i]); 1705 id->userprovided = options.identity_file_userprovided[i]; 1706 TAILQ_INSERT_TAIL(&files, id, next); 1707 } 1708 /* list of certificates specified by user */ 1709 for (i = 0; i < options.num_certificate_files; i++) { 1710 key = options.certificates[i]; 1711 if (!sshkey_is_cert(key) || key->cert == NULL || 1712 key->cert->type != SSH2_CERT_TYPE_USER) { 1713 debug_f("ignoring certificate %s: not a user " 1714 "certificate", options.identity_files[i]); 1715 continue; 1716 } 1717 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1718 debug_f("ignoring authenticator-hosted key " 1719 "certificate %s as no " 1720 "SecurityKeyProvider has been specified", 1721 options.identity_files[i]); 1722 continue; 1723 } 1724 id = xcalloc(1, sizeof(*id)); 1725 id->agent_fd = -1; 1726 id->key = key; 1727 id->filename = xstrdup(options.certificate_files[i]); 1728 id->userprovided = options.certificate_file_userprovided[i]; 1729 TAILQ_INSERT_TAIL(preferred, id, next); 1730 } 1731 /* list of keys supported by the agent */ 1732 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1733 for (j = 0; j < idlist->nkeys; j++) { 1734 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1735 options.required_rsa_size)) != 0) { 1736 debug_fr(r, "ignoring %s agent key", 1737 sshkey_ssh_name(idlist->keys[j])); 1738 continue; 1739 } 1740 found = 0; 1741 TAILQ_FOREACH(id, &files, next) { 1742 /* 1743 * agent keys from the config file are 1744 * preferred 1745 */ 1746 if (sshkey_equal(idlist->keys[j], id->key)) { 1747 TAILQ_REMOVE(&files, id, next); 1748 TAILQ_INSERT_TAIL(preferred, id, next); 1749 id->agent_fd = agent_fd; 1750 found = 1; 1751 break; 1752 } 1753 } 1754 if (!found && !options.identities_only) { 1755 id = xcalloc(1, sizeof(*id)); 1756 /* XXX "steals" key/comment from idlist */ 1757 id->key = idlist->keys[j]; 1758 id->filename = idlist->comments[j]; 1759 idlist->keys[j] = NULL; 1760 idlist->comments[j] = NULL; 1761 id->agent_fd = agent_fd; 1762 TAILQ_INSERT_TAIL(&agent, id, next); 1763 } 1764 } 1765 ssh_free_identitylist(idlist); 1766 /* append remaining agent keys */ 1767 TAILQ_CONCAT(preferred, &agent, next); 1768 authctxt->agent_fd = agent_fd; 1769 } 1770 /* Prefer PKCS11 keys that are explicitly listed */ 1771 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1772 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1773 continue; 1774 found = 0; 1775 TAILQ_FOREACH(id2, &files, next) { 1776 if (id2->key == NULL || 1777 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1778 continue; 1779 if (sshkey_equal(id->key, id2->key)) { 1780 TAILQ_REMOVE(&files, id, next); 1781 TAILQ_INSERT_TAIL(preferred, id, next); 1782 found = 1; 1783 break; 1784 } 1785 } 1786 /* If IdentitiesOnly set and key not found then don't use it */ 1787 if (!found && options.identities_only) { 1788 TAILQ_REMOVE(&files, id, next); 1789 freezero(id, sizeof(*id)); 1790 } 1791 } 1792 /* append remaining keys from the config file */ 1793 TAILQ_CONCAT(preferred, &files, next); 1794 /* finally, filter by PubkeyAcceptedAlgorithms */ 1795 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1796 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1797 debug("Skipping %s key %s - " 1798 "corresponding algo not in PubkeyAcceptedAlgorithms", 1799 sshkey_ssh_name(id->key), id->filename); 1800 TAILQ_REMOVE(preferred, id, next); 1801 sshkey_free(id->key); 1802 free(id->filename); 1803 memset(id, 0, sizeof(*id)); 1804 continue; 1805 } 1806 } 1807 /* List the keys we plan on using */ 1808 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1809 ident = format_identity(id); 1810 debug("Will attempt key: %s", ident); 1811 free(ident); 1812 } 1813 debug2_f("done"); 1814 } 1815 1816 static void 1817 pubkey_cleanup(struct ssh *ssh) 1818 { 1819 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1820 Identity *id; 1821 1822 if (authctxt->agent_fd != -1) { 1823 ssh_close_authentication_socket(authctxt->agent_fd); 1824 authctxt->agent_fd = -1; 1825 } 1826 for (id = TAILQ_FIRST(&authctxt->keys); id; 1827 id = TAILQ_FIRST(&authctxt->keys)) { 1828 TAILQ_REMOVE(&authctxt->keys, id, next); 1829 sshkey_free(id->key); 1830 free(id->filename); 1831 free(id); 1832 } 1833 } 1834 1835 static void 1836 pubkey_reset(Authctxt *authctxt) 1837 { 1838 Identity *id; 1839 1840 TAILQ_FOREACH(id, &authctxt->keys, next) 1841 id->tried = 0; 1842 } 1843 1844 static int 1845 userauth_pubkey(struct ssh *ssh) 1846 { 1847 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1848 Identity *id; 1849 int sent = 0; 1850 char *ident; 1851 1852 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1853 if (id->tried++) 1854 return (0); 1855 /* move key to the end of the queue */ 1856 TAILQ_REMOVE(&authctxt->keys, id, next); 1857 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1858 /* 1859 * send a test message if we have the public key. for 1860 * encrypted keys we cannot do this and have to load the 1861 * private key instead 1862 */ 1863 if (id->key != NULL) { 1864 ident = format_identity(id); 1865 debug("Offering public key: %s", ident); 1866 free(ident); 1867 sent = send_pubkey_test(ssh, id); 1868 } else { 1869 debug("Trying private key: %s", id->filename); 1870 id->key = load_identity_file(id); 1871 if (id->key != NULL) { 1872 if (id->key != NULL) { 1873 id->isprivate = 1; 1874 sent = sign_and_send_pubkey(ssh, id); 1875 } 1876 sshkey_free(id->key); 1877 id->key = NULL; 1878 id->isprivate = 0; 1879 } 1880 } 1881 if (sent) 1882 return (sent); 1883 } 1884 return (0); 1885 } 1886 1887 /* 1888 * Send userauth request message specifying keyboard-interactive method. 1889 */ 1890 static int 1891 userauth_kbdint(struct ssh *ssh) 1892 { 1893 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1894 int r; 1895 1896 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1897 return 0; 1898 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1899 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1900 debug3("userauth_kbdint: disable: no info_req_seen"); 1901 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1902 return 0; 1903 } 1904 1905 debug2("userauth_kbdint"); 1906 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1907 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1908 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1909 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1910 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1911 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1912 options.kbd_interactive_devices : "")) != 0 || 1913 (r = sshpkt_send(ssh)) != 0) 1914 fatal_fr(r, "send packet"); 1915 1916 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1917 return 1; 1918 } 1919 1920 /* 1921 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1922 */ 1923 static int 1924 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1925 { 1926 Authctxt *authctxt = ssh->authctxt; 1927 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1928 char *display_prompt = NULL, *response = NULL; 1929 u_char echo = 0; 1930 u_int num_prompts, i; 1931 int r; 1932 1933 debug2_f("entering"); 1934 1935 if (authctxt == NULL) 1936 fatal_f("no authentication context"); 1937 1938 authctxt->info_req_seen = 1; 1939 1940 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1941 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1942 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1943 goto out; 1944 if (strlen(name) > 0) 1945 logit("%s", name); 1946 if (strlen(inst) > 0) 1947 logit("%s", inst); 1948 1949 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1950 goto out; 1951 /* 1952 * Begin to build info response packet based on prompts requested. 1953 * We commit to providing the correct number of responses, so if 1954 * further on we run into a problem that prevents this, we have to 1955 * be sure and clean this up and send a correct error response. 1956 */ 1957 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1958 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1959 goto out; 1960 1961 debug2_f("num_prompts %d", num_prompts); 1962 for (i = 0; i < num_prompts; i++) { 1963 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1964 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1965 goto out; 1966 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1967 authctxt->server_user, options.host_key_alias ? 1968 options.host_key_alias : authctxt->host, prompt) == -1) 1969 fatal_f("asmprintf failed"); 1970 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1971 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1972 goto out; 1973 freezero(response, strlen(response)); 1974 free(prompt); 1975 free(display_prompt); 1976 display_prompt = response = prompt = NULL; 1977 } 1978 /* done with parsing incoming message. */ 1979 if ((r = sshpkt_get_end(ssh)) != 0 || 1980 (r = sshpkt_add_padding(ssh, 64)) != 0) 1981 goto out; 1982 r = sshpkt_send(ssh); 1983 out: 1984 if (response) 1985 freezero(response, strlen(response)); 1986 free(prompt); 1987 free(display_prompt); 1988 free(name); 1989 free(inst); 1990 free(lang); 1991 return r; 1992 } 1993 1994 static int 1995 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1996 const u_char *data, size_t datalen) 1997 { 1998 struct sshbuf *b; 1999 struct stat st; 2000 pid_t pid; 2001 int r, to[2], from[2], status; 2002 int sock = ssh_packet_get_connection_in(ssh); 2003 u_char rversion = 0, version = 2; 2004 void (*osigchld)(int); 2005 2006 *sigp = NULL; 2007 *lenp = 0; 2008 2009 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2010 error_f("not installed: %s", strerror(errno)); 2011 return -1; 2012 } 2013 if (fflush(stdout) != 0) { 2014 error_f("fflush: %s", strerror(errno)); 2015 return -1; 2016 } 2017 if (pipe(to) == -1) { 2018 error_f("pipe: %s", strerror(errno)); 2019 return -1; 2020 } 2021 if (pipe(from) == -1) { 2022 error_f("pipe: %s", strerror(errno)); 2023 return -1; 2024 } 2025 if ((pid = fork()) == -1) { 2026 error_f("fork: %s", strerror(errno)); 2027 return -1; 2028 } 2029 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2030 if (pid == 0) { 2031 close(from[0]); 2032 if (dup2(from[1], STDOUT_FILENO) == -1) 2033 fatal_f("dup2: %s", strerror(errno)); 2034 close(to[1]); 2035 if (dup2(to[0], STDIN_FILENO) == -1) 2036 fatal_f("dup2: %s", strerror(errno)); 2037 close(from[1]); 2038 close(to[0]); 2039 2040 if (dup2(sock, STDERR_FILENO + 1) == -1) 2041 fatal_f("dup2: %s", strerror(errno)); 2042 sock = STDERR_FILENO + 1; 2043 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2044 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2045 closefrom(sock + 1); 2046 2047 debug3_f("[child] pid=%ld, exec %s", 2048 (long)getpid(), _PATH_SSH_KEY_SIGN); 2049 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2050 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2051 strerror(errno)); 2052 } 2053 close(from[1]); 2054 close(to[0]); 2055 sock = STDERR_FILENO + 1; 2056 2057 if ((b = sshbuf_new()) == NULL) 2058 fatal_f("sshbuf_new failed"); 2059 /* send # of sock, data to be signed */ 2060 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2061 (r = sshbuf_put_string(b, data, datalen)) != 0) 2062 fatal_fr(r, "buffer error"); 2063 if (ssh_msg_send(to[1], version, b) == -1) 2064 fatal_f("couldn't send request"); 2065 sshbuf_reset(b); 2066 r = ssh_msg_recv(from[0], b); 2067 close(from[0]); 2068 close(to[1]); 2069 if (r < 0) { 2070 error_f("no reply"); 2071 goto fail; 2072 } 2073 2074 errno = 0; 2075 while (waitpid(pid, &status, 0) == -1) { 2076 if (errno != EINTR) { 2077 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2078 goto fail; 2079 } 2080 } 2081 if (!WIFEXITED(status)) { 2082 error_f("exited abnormally"); 2083 goto fail; 2084 } 2085 if (WEXITSTATUS(status) != 0) { 2086 error_f("exited with status %d", WEXITSTATUS(status)); 2087 goto fail; 2088 } 2089 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2090 error_fr(r, "buffer error"); 2091 goto fail; 2092 } 2093 if (rversion != version) { 2094 error_f("bad version"); 2095 goto fail; 2096 } 2097 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2098 error_fr(r, "buffer error"); 2099 fail: 2100 ssh_signal(SIGCHLD, osigchld); 2101 sshbuf_free(b); 2102 return -1; 2103 } 2104 ssh_signal(SIGCHLD, osigchld); 2105 sshbuf_free(b); 2106 2107 return 0; 2108 } 2109 2110 static int 2111 userauth_hostbased(struct ssh *ssh) 2112 { 2113 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2114 struct sshkey *private = NULL; 2115 struct sshbuf *b = NULL; 2116 u_char *sig = NULL, *keyblob = NULL; 2117 char *fp = NULL, *chost = NULL, *lname = NULL; 2118 size_t siglen = 0, keylen = 0; 2119 int i, r, success = 0; 2120 2121 if (authctxt->ktypes == NULL) { 2122 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2123 authctxt->ktypes = authctxt->oktypes; 2124 } 2125 2126 /* 2127 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2128 * trying each hostkey that matches the type in turn. 2129 */ 2130 for (;;) { 2131 if (authctxt->active_ktype == NULL) 2132 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2133 if (authctxt->active_ktype == NULL || 2134 *authctxt->active_ktype == '\0') 2135 break; 2136 debug3_f("trying key type %s", authctxt->active_ktype); 2137 2138 /* check for a useful key */ 2139 private = NULL; 2140 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2141 if (authctxt->sensitive->keys[i] == NULL || 2142 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2143 continue; 2144 if (!sshkey_match_keyname_to_sigalgs( 2145 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2146 authctxt->active_ktype)) 2147 continue; 2148 /* we take and free the key */ 2149 private = authctxt->sensitive->keys[i]; 2150 authctxt->sensitive->keys[i] = NULL; 2151 break; 2152 } 2153 /* Found one */ 2154 if (private != NULL) 2155 break; 2156 /* No more keys of this type; advance */ 2157 authctxt->active_ktype = NULL; 2158 } 2159 if (private == NULL) { 2160 free(authctxt->oktypes); 2161 authctxt->oktypes = authctxt->ktypes = NULL; 2162 authctxt->active_ktype = NULL; 2163 debug("No more client hostkeys for hostbased authentication."); 2164 goto out; 2165 } 2166 2167 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2168 SSH_FP_DEFAULT)) == NULL) { 2169 error_f("sshkey_fingerprint failed"); 2170 goto out; 2171 } 2172 debug_f("trying hostkey %s %s using sigalg %s", 2173 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2174 2175 /* figure out a name for the client host */ 2176 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2177 if (lname == NULL) { 2178 error_f("cannot get local ipaddr/name"); 2179 goto out; 2180 } 2181 2182 /* XXX sshbuf_put_stringf? */ 2183 xasprintf(&chost, "%s.", lname); 2184 debug2_f("chost %s", chost); 2185 2186 /* construct data */ 2187 if ((b = sshbuf_new()) == NULL) { 2188 error_f("sshbuf_new failed"); 2189 goto out; 2190 } 2191 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2192 error_fr(r, "sshkey_to_blob"); 2193 goto out; 2194 } 2195 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2196 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2197 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2198 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2199 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2200 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2201 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2202 (r = sshbuf_put_cstring(b, chost)) != 0 || 2203 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2204 error_fr(r, "buffer error"); 2205 goto out; 2206 } 2207 2208 #ifdef DEBUG_PK 2209 sshbuf_dump(b, stderr); 2210 #endif 2211 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2212 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2213 error("sign using hostkey %s %s failed", 2214 sshkey_ssh_name(private), fp); 2215 goto out; 2216 } 2217 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2218 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2219 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2220 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2221 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2222 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2223 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2224 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2225 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2226 (r = sshpkt_send(ssh)) != 0) { 2227 error_fr(r, "packet error"); 2228 goto out; 2229 } 2230 success = 1; 2231 2232 out: 2233 if (sig != NULL) 2234 freezero(sig, siglen); 2235 free(keyblob); 2236 free(lname); 2237 free(fp); 2238 free(chost); 2239 sshkey_free(private); 2240 sshbuf_free(b); 2241 2242 return success; 2243 } 2244 2245 /* find auth method */ 2246 2247 /* 2248 * given auth method name, if configurable options permit this method fill 2249 * in auth_ident field and return true, otherwise return false. 2250 */ 2251 static int 2252 authmethod_is_enabled(Authmethod *method) 2253 { 2254 if (method == NULL) 2255 return 0; 2256 /* return false if options indicate this method is disabled */ 2257 if (method->enabled == NULL || *method->enabled == 0) 2258 return 0; 2259 /* return false if batch mode is enabled but method needs interactive mode */ 2260 if (method->batch_flag != NULL && *method->batch_flag != 0) 2261 return 0; 2262 return 1; 2263 } 2264 2265 static Authmethod * 2266 authmethod_lookup(const char *name) 2267 { 2268 Authmethod *method = NULL; 2269 if (name != NULL) 2270 for (method = authmethods; method->name != NULL; method++) 2271 if (strcmp(name, method->name) == 0) 2272 return method; 2273 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2274 return NULL; 2275 } 2276 2277 /* XXX internal state */ 2278 static Authmethod *current = NULL; 2279 static char *supported = NULL; 2280 static char *preferred = NULL; 2281 2282 /* 2283 * Given the authentication method list sent by the server, return the 2284 * next method we should try. If the server initially sends a nil list, 2285 * use a built-in default list. 2286 */ 2287 static Authmethod * 2288 authmethod_get(char *authlist) 2289 { 2290 char *name = NULL; 2291 u_int next; 2292 2293 /* Use a suitable default if we're passed a nil list. */ 2294 if (authlist == NULL || strlen(authlist) == 0) 2295 authlist = options.preferred_authentications; 2296 2297 if (supported == NULL || strcmp(authlist, supported) != 0) { 2298 debug3("start over, passed a different list %s", authlist); 2299 free(supported); 2300 supported = xstrdup(authlist); 2301 preferred = options.preferred_authentications; 2302 debug3("preferred %s", preferred); 2303 current = NULL; 2304 } else if (current != NULL && authmethod_is_enabled(current)) 2305 return current; 2306 2307 for (;;) { 2308 if ((name = match_list(preferred, supported, &next)) == NULL) { 2309 debug("No more authentication methods to try."); 2310 current = NULL; 2311 return NULL; 2312 } 2313 preferred += next; 2314 debug3("authmethod_lookup %s", name); 2315 debug3("remaining preferred: %s", preferred); 2316 if ((current = authmethod_lookup(name)) != NULL && 2317 authmethod_is_enabled(current)) { 2318 debug3("authmethod_is_enabled %s", name); 2319 debug("Next authentication method: %s", name); 2320 free(name); 2321 return current; 2322 } 2323 free(name); 2324 } 2325 } 2326 2327 static char * 2328 authmethods_get(void) 2329 { 2330 Authmethod *method = NULL; 2331 struct sshbuf *b; 2332 char *list; 2333 int r; 2334 2335 if ((b = sshbuf_new()) == NULL) 2336 fatal_f("sshbuf_new failed"); 2337 for (method = authmethods; method->name != NULL; method++) { 2338 if (authmethod_is_enabled(method)) { 2339 if ((r = sshbuf_putf(b, "%s%s", 2340 sshbuf_len(b) ? "," : "", method->name)) != 0) 2341 fatal_fr(r, "buffer error"); 2342 } 2343 } 2344 if ((list = sshbuf_dup_string(b)) == NULL) 2345 fatal_f("sshbuf_dup_string failed"); 2346 sshbuf_free(b); 2347 return list; 2348 } 2349
Indexes created Fri Mar 06 19:51:54 UTC 2026