1 /* $NetBSD: sshconnect2.c,v 1.44 2023/07/26 17:58:16 christos Exp $ */ 2 /* $OpenBSD: sshconnect2.c,v 1.366 2023/03/09 07:11:05 dtucker Exp $ */ 3 /* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * Copyright (c) 2008 Damien Miller. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: sshconnect2.c,v 1.44 2023/07/26 17:58:16 christos Exp $"); 30 #include <sys/types.h> 31 #include <sys/socket.h> 32 #include <sys/wait.h> 33 #include <sys/queue.h> 34 #include <sys/stat.h> 35 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <limits.h> 39 #include <netdb.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdarg.h> 43 #include <signal.h> 44 #include <pwd.h> 45 #include <unistd.h> 46 #include <vis.h> 47 48 #ifdef KRB5 49 #include <krb5.h> 50 #endif 51 52 #include "xmalloc.h" 53 #include "ssh.h" 54 #include "ssh2.h" 55 #include "sshbuf.h" 56 #include "packet.h" 57 #include "compat.h" 58 #include "cipher.h" 59 #include "sshkey.h" 60 #include "kex.h" 61 #include "sshconnect.h" 62 #include "authfile.h" 63 #include "dh.h" 64 #include "authfd.h" 65 #include "log.h" 66 #include "misc.h" 67 #include "readconf.h" 68 #include "match.h" 69 #include "dispatch.h" 70 #include "canohost.h" 71 #include "msg.h" 72 #include "pathnames.h" 73 #include "uidswap.h" 74 #include "hostfile.h" 75 #include "ssherr.h" 76 #include "utf8.h" 77 #include "ssh-sk.h" 78 #include "sk-api.h" 79 /* XXX */ 80 struct sshauthopt *auth_opts; 81 const char *auth_get_canonical_hostname(struct ssh *, int); 82 83 #ifdef GSSAPI 84 #include "ssh-gss.h" 85 #endif 86 #ifdef KRB5 87 static int userauth_kerberos(struct ssh *); 88 #endif 89 90 /* import */ 91 extern char *client_version_string; 92 extern char *server_version_string; 93 extern Options options; 94 95 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */ 96 /* if it is set then prevent the switch to the null cipher */ 97 98 extern int tty_flag; 99 100 /* 101 * SSH2 key exchange 102 */ 103 104 static char *xxx_host; 105 static struct sockaddr *xxx_hostaddr; 106 static const struct ssh_conn_info *xxx_conn_info; 107 108 static int 109 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 110 { 111 int r; 112 113 if ((r = sshkey_check_rsa_length(hostkey, 114 options.required_rsa_size)) != 0) 115 fatal_r(r, "Bad server host key"); 116 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 117 xxx_conn_info) == -1) 118 fatal("Host key verification failed."); 119 return 0; 120 } 121 122 /* Returns the first item from a comma-separated algorithm list */ 123 static char * 124 first_alg(const char *algs) 125 { 126 char *ret, *cp; 127 128 ret = xstrdup(algs); 129 if ((cp = strchr(ret, ',')) != NULL) 130 *cp = '\0'; 131 return ret; 132 } 133 134 static char * 135 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 136 const struct ssh_conn_info *cinfo) 137 { 138 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 139 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 140 size_t maxlen; 141 struct hostkeys *hostkeys = NULL; 142 int ktype; 143 u_int i; 144 145 /* Find all hostkeys for this hostname */ 146 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 147 hostkeys = init_hostkeys(); 148 for (i = 0; i < options.num_user_hostfiles; i++) 149 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 150 for (i = 0; i < options.num_system_hostfiles; i++) { 151 load_hostkeys(hostkeys, hostname, 152 options.system_hostfiles[i], 0); 153 } 154 if (options.known_hosts_command != NULL) { 155 load_hostkeys_command(hostkeys, options.known_hosts_command, 156 "ORDER", cinfo, NULL, host); 157 } 158 /* 159 * If a plain public key exists that matches the type of the best 160 * preference HostkeyAlgorithms, then use the whole list as is. 161 * Note that we ignore whether the best preference algorithm is a 162 * certificate type, as sshconnect.c will downgrade certs to 163 * plain keys if necessary. 164 */ 165 best = first_alg(options.hostkeyalgorithms); 166 if (lookup_key_in_hostkeys_by_type(hostkeys, 167 sshkey_type_plain(sshkey_type_from_name(best)), 168 sshkey_ecdsa_nid_from_name(best), NULL)) { 169 debug3_f("have matching best-preference key type %s, " 170 "using HostkeyAlgorithms verbatim", best); 171 ret = xstrdup(options.hostkeyalgorithms); 172 goto out; 173 } 174 175 /* 176 * Otherwise, prefer the host key algorithms that match known keys 177 * while keeping the ordering of HostkeyAlgorithms as much as possible. 178 */ 179 oavail = avail = xstrdup(options.hostkeyalgorithms); 180 maxlen = strlen(avail) + 1; 181 first = xmalloc(maxlen); 182 last = xmalloc(maxlen); 183 *first = *last = '\0'; 184 185 #define ALG_APPEND(to, from) \ 186 do { \ 187 if (*to != '\0') \ 188 strlcat(to, ",", maxlen); \ 189 strlcat(to, from, maxlen); \ 190 } while (0) 191 192 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 193 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 194 fatal_f("unknown alg %s", alg); 195 /* 196 * If we have a @cert-authority marker in known_hosts then 197 * prefer all certificate algorithms. 198 */ 199 if (sshkey_type_is_cert(ktype) && 200 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 201 ALG_APPEND(first, alg); 202 continue; 203 } 204 /* If the key appears in known_hosts then prefer it */ 205 if (lookup_key_in_hostkeys_by_type(hostkeys, 206 sshkey_type_plain(ktype), 207 sshkey_ecdsa_nid_from_name(alg), NULL)) { 208 ALG_APPEND(first, alg); 209 continue; 210 } 211 /* Otherwise, put it last */ 212 ALG_APPEND(last, alg); 213 } 214 #undef ALG_APPEND 215 xasprintf(&ret, "%s%s%s", first, 216 (*first == '\0' || *last == '\0') ? "" : ",", last); 217 if (*first != '\0') 218 debug3_f("prefer hostkeyalgs: %s", first); 219 else 220 debug3_f("no algorithms matched; accept original"); 221 out: 222 free(best); 223 free(first); 224 free(last); 225 free(hostname); 226 free(oavail); 227 free_hostkeys(hostkeys); 228 229 return ret; 230 } 231 232 void 233 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 234 const struct ssh_conn_info *cinfo) 235 { 236 char *myproposal[PROPOSAL_MAX]; 237 char *s, *all_key, *hkalgs = NULL; 238 int r, use_known_hosts_order = 0; 239 240 xxx_host = host; 241 xxx_hostaddr = hostaddr; 242 xxx_conn_info = cinfo; 243 244 if (options.rekey_limit || options.rekey_interval) 245 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 246 options.rekey_interval); 247 248 /* 249 * If the user has not specified HostkeyAlgorithms, or has only 250 * appended or removed algorithms from that list then prefer algorithms 251 * that are in the list that are supported by known_hosts keys. 252 */ 253 if (options.hostkeyalgorithms == NULL || 254 options.hostkeyalgorithms[0] == '-' || 255 options.hostkeyalgorithms[0] == '+') 256 use_known_hosts_order = 1; 257 258 /* Expand or fill in HostkeyAlgorithms */ 259 all_key = sshkey_alg_list(0, 0, 1, ','); 260 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 261 kex_default_pk_alg(), all_key)) != 0) 262 fatal_fr(r, "kex_assemble_namelist"); 263 free(all_key); 264 265 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 266 fatal_f("kex_names_cat"); 267 268 if (use_known_hosts_order) 269 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo); 270 271 kex_proposal_populate_entries(ssh, myproposal, s, options.ciphers, 272 options.macs, compression_alg_list(options.compression), 273 hkalgs ? hkalgs : options.hostkeyalgorithms); 274 275 free(hkalgs); 276 277 /* start key exchange */ 278 if ((r = kex_setup(ssh, myproposal)) != 0) 279 fatal_r(r, "kex_setup"); 280 #ifdef WITH_OPENSSL 281 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 282 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 283 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 284 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 285 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 286 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 287 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 288 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 289 #endif 290 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 291 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 292 ssh->kex->verify_host_key=&verify_host_key_callback; 293 294 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 295 296 /* remove ext-info from the KEX proposals for rekeying */ 297 free(myproposal[PROPOSAL_KEX_ALGS]); 298 myproposal[PROPOSAL_KEX_ALGS] = 299 compat_kex_proposal(ssh, options.kex_algorithms); 300 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 301 fatal_r(r, "kex_prop2buf"); 302 303 #ifdef DEBUG_KEXDH 304 /* send 1st encrypted/maced/compressed message */ 305 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 306 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 307 (r = sshpkt_send(ssh)) != 0 || 308 (r = ssh_packet_write_wait(ssh)) < 0) 309 fatal_fr(r, "send packet"); 310 #endif 311 kex_proposal_free_entries(myproposal); 312 } 313 314 /* 315 * Authenticate user 316 */ 317 318 typedef struct cauthctxt Authctxt; 319 typedef struct cauthmethod Authmethod; 320 typedef struct identity Identity; 321 typedef struct idlist Idlist; 322 323 struct identity { 324 TAILQ_ENTRY(identity) next; 325 int agent_fd; /* >=0 if agent supports key */ 326 struct sshkey *key; /* public/private key */ 327 char *filename; /* comment for agent-only keys */ 328 int tried; 329 int isprivate; /* key points to the private key */ 330 int userprovided; 331 }; 332 TAILQ_HEAD(idlist, identity); 333 334 struct cauthctxt { 335 const char *server_user; 336 const char *local_user; 337 const char *host; 338 const char *service; 339 struct cauthmethod *method; 340 sig_atomic_t success; 341 char *authlist; 342 #ifdef GSSAPI 343 /* gssapi */ 344 gss_OID_set gss_supported_mechs; 345 u_int mech_tried; 346 #endif 347 /* pubkey */ 348 struct idlist keys; 349 int agent_fd; 350 /* hostbased */ 351 Sensitive *sensitive; 352 char *oktypes, *ktypes; 353 const char *active_ktype; 354 /* kbd-interactive */ 355 int info_req_seen; 356 int attempt_kbdint; 357 /* password */ 358 int attempt_passwd; 359 /* generic */ 360 void *methoddata; 361 }; 362 363 struct cauthmethod { 364 const char *name; /* string to compare against server's list */ 365 int (*userauth)(struct ssh *ssh); 366 void (*cleanup)(struct ssh *ssh); 367 int *enabled; /* flag in option struct that enables method */ 368 int *batch_flag; /* flag in option struct that disables method */ 369 }; 370 371 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 372 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 373 static int input_userauth_success(int, u_int32_t, struct ssh *); 374 static int input_userauth_failure(int, u_int32_t, struct ssh *); 375 static int input_userauth_banner(int, u_int32_t, struct ssh *); 376 static int input_userauth_error(int, u_int32_t, struct ssh *); 377 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 378 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 379 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 380 381 static int userauth_none(struct ssh *); 382 static int userauth_pubkey(struct ssh *); 383 static int userauth_passwd(struct ssh *); 384 static int userauth_kbdint(struct ssh *); 385 static int userauth_hostbased(struct ssh *); 386 387 #ifdef GSSAPI 388 static int userauth_gssapi(struct ssh *); 389 static void userauth_gssapi_cleanup(struct ssh *); 390 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 391 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 392 static int input_gssapi_error(int, u_int32_t, struct ssh *); 393 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 394 #endif 395 396 void userauth(struct ssh *, char *); 397 398 static void pubkey_cleanup(struct ssh *); 399 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 400 static void pubkey_prepare(struct ssh *, Authctxt *); 401 static void pubkey_reset(Authctxt *); 402 static struct sshkey *load_identity_file(Identity *); 403 404 static Authmethod *authmethod_get(char *authlist); 405 static Authmethod *authmethod_lookup(const char *name); 406 static char *authmethods_get(void); 407 408 Authmethod authmethods[] = { 409 #ifdef GSSAPI 410 {"gssapi-with-mic", 411 userauth_gssapi, 412 userauth_gssapi_cleanup, 413 &options.gss_authentication, 414 NULL}, 415 #endif 416 {"hostbased", 417 userauth_hostbased, 418 NULL, 419 &options.hostbased_authentication, 420 NULL}, 421 #if KRB5 422 {"kerberos-2@ssh.com", 423 userauth_kerberos, 424 NULL, 425 &options.kerberos_authentication, 426 NULL}, 427 #endif 428 {"publickey", 429 userauth_pubkey, 430 NULL, 431 &options.pubkey_authentication, 432 NULL}, 433 {"keyboard-interactive", 434 userauth_kbdint, 435 NULL, 436 &options.kbd_interactive_authentication, 437 &options.batch_mode}, 438 {"password", 439 userauth_passwd, 440 NULL, 441 &options.password_authentication, 442 &options.batch_mode}, 443 {"none", 444 userauth_none, 445 NULL, 446 NULL, 447 NULL}, 448 {NULL, NULL, NULL, NULL, NULL} 449 }; 450 451 void 452 ssh_userauth2(struct ssh *ssh, const char *local_user, 453 const char *server_user, char *host, Sensitive *sensitive) 454 { 455 Authctxt authctxt; 456 int r; 457 458 if (options.preferred_authentications == NULL) 459 options.preferred_authentications = authmethods_get(); 460 461 /* setup authentication context */ 462 memset(&authctxt, 0, sizeof(authctxt)); 463 authctxt.server_user = server_user; 464 authctxt.local_user = local_user; 465 authctxt.host = host; 466 authctxt.service = "ssh-connection"; /* service name */ 467 authctxt.success = 0; 468 authctxt.method = authmethod_lookup("none"); 469 authctxt.authlist = NULL; 470 authctxt.methoddata = NULL; 471 authctxt.sensitive = sensitive; 472 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 473 authctxt.info_req_seen = 0; 474 authctxt.attempt_kbdint = 0; 475 authctxt.attempt_passwd = 0; 476 #if GSSAPI 477 authctxt.gss_supported_mechs = NULL; 478 authctxt.mech_tried = 0; 479 #endif 480 authctxt.agent_fd = -1; 481 pubkey_prepare(ssh, &authctxt); 482 if (authctxt.method == NULL) { 483 fatal_f("internal error: cannot send userauth none request"); 484 } 485 486 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 487 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 488 (r = sshpkt_send(ssh)) != 0) 489 fatal_fr(r, "send packet"); 490 491 ssh->authctxt = &authctxt; 492 ssh_dispatch_init(ssh, &input_userauth_error); 493 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 494 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 495 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 496 pubkey_cleanup(ssh); 497 ssh->authctxt = NULL; 498 499 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 500 501 /* if the user wants to use the none cipher do it */ 502 /* post authentication and only if the right conditions are met */ 503 /* both of the NONE commands must be true and there must be no */ 504 /* tty allocated */ 505 if ((options.none_switch == 1) && (options.none_enabled == 1)) 506 { 507 if (tty_flag) /* no null on tty sessions */ 508 { 509 /* requested NONE cipher when in a tty */ 510 debug("Cannot switch to NONE cipher with tty allocated"); 511 fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n"); 512 } 513 } 514 if (!authctxt.success) 515 fatal("Authentication failed."); 516 517 if (ssh_packet_connection_is_on_socket(ssh)) { 518 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 519 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 520 authctxt.method->name); 521 } else { 522 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 523 authctxt.method->name); 524 } 525 } 526 527 static int 528 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 529 { 530 int r; 531 532 if (ssh_packet_remaining(ssh) > 0) { 533 char *reply; 534 535 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 536 goto out; 537 debug2("service_accept: %s", reply); 538 free(reply); 539 } else { 540 debug2("buggy server: service_accept w/o service"); 541 } 542 if ((r = sshpkt_get_end(ssh)) != 0) 543 goto out; 544 debug("SSH2_MSG_SERVICE_ACCEPT received"); 545 546 /* initial userauth request */ 547 userauth_none(ssh); 548 549 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 550 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 551 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 552 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 553 r = 0; 554 out: 555 return r; 556 } 557 558 static int 559 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 560 { 561 return kex_input_ext_info(type, seqnr, ssh); 562 } 563 564 void 565 userauth(struct ssh *ssh, char *authlist) 566 { 567 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 568 569 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 570 authctxt->method->cleanup(ssh); 571 572 free(authctxt->methoddata); 573 authctxt->methoddata = NULL; 574 if (authlist == NULL) { 575 authlist = authctxt->authlist; 576 } else { 577 free(authctxt->authlist); 578 authctxt->authlist = authlist; 579 } 580 for (;;) { 581 Authmethod *method = authmethod_get(authlist); 582 if (method == NULL) 583 fatal("%s@%s: Permission denied (%s).", 584 authctxt->server_user, authctxt->host, authlist); 585 authctxt->method = method; 586 587 /* reset the per method handler */ 588 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 589 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 590 591 /* and try new method */ 592 if (method->userauth(ssh) != 0) { 593 debug2("we sent a %s packet, wait for reply", method->name); 594 break; 595 } else { 596 debug2("we did not send a packet, disable method"); 597 method->enabled = NULL; 598 } 599 } 600 } 601 602 static int 603 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 604 { 605 fatal_f("bad message during authentication: type %d", type); 606 return 0; 607 } 608 609 static int 610 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 611 { 612 char *msg = NULL; 613 size_t len; 614 int r; 615 616 debug3_f("entering"); 617 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 618 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 619 goto out; 620 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 621 fmprintf(stderr, "%s", msg); 622 r = 0; 623 out: 624 free(msg); 625 return r; 626 } 627 628 static int 629 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 630 { 631 Authctxt *authctxt = ssh->authctxt; 632 633 if (authctxt == NULL) 634 fatal_f("no authentication context"); 635 free(authctxt->authlist); 636 authctxt->authlist = NULL; 637 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 638 authctxt->method->cleanup(ssh); 639 free(authctxt->methoddata); 640 authctxt->methoddata = NULL; 641 authctxt->success = 1; /* break out */ 642 return 0; 643 } 644 645 #if 0 646 static int 647 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 648 { 649 Authctxt *authctxt = ssh->authctxt; 650 651 if (authctxt == NULL) 652 fatal_f("no authentication context"); 653 654 fatal("Unexpected authentication success during %s.", 655 authctxt->method->name); 656 return 0; 657 } 658 #endif 659 660 static int 661 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 662 { 663 Authctxt *authctxt = ssh->authctxt; 664 char *authlist = NULL; 665 u_char partial; 666 667 if (authctxt == NULL) 668 fatal("input_userauth_failure: no authentication context"); 669 670 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 671 sshpkt_get_u8(ssh, &partial) != 0 || 672 sshpkt_get_end(ssh) != 0) 673 goto out; 674 675 if (partial != 0) { 676 verbose("Authenticated using \"%s\" with partial success.", 677 authctxt->method->name); 678 /* reset state */ 679 pubkey_reset(authctxt); 680 } 681 debug("Authentications that can continue: %s", authlist); 682 683 userauth(ssh, authlist); 684 authlist = NULL; 685 out: 686 free(authlist); 687 return 0; 688 } 689 690 /* 691 * Format an identity for logging including filename, key type, fingerprint 692 * and location (agent, etc.). Caller must free. 693 */ 694 static char * 695 format_identity(Identity *id) 696 { 697 char *fp = NULL, *ret = NULL; 698 const char *note = ""; 699 700 if (id->key != NULL) { 701 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 702 SSH_FP_DEFAULT); 703 } 704 if (id->key) { 705 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 706 note = " token"; 707 else if (sshkey_is_sk(id->key)) 708 note = " authenticator"; 709 } 710 xasprintf(&ret, "%s %s%s%s%s%s%s", 711 id->filename, 712 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 713 fp ? fp : "", 714 id->userprovided ? " explicit" : "", note, 715 id->agent_fd != -1 ? " agent" : ""); 716 free(fp); 717 return ret; 718 } 719 720 static int 721 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 722 { 723 Authctxt *authctxt = ssh->authctxt; 724 struct sshkey *key = NULL; 725 Identity *id = NULL; 726 int pktype, found = 0, sent = 0; 727 size_t blen; 728 char *pkalg = NULL, *fp = NULL, *ident = NULL; 729 u_char *pkblob = NULL; 730 int r; 731 732 if (authctxt == NULL) 733 fatal("input_userauth_pk_ok: no authentication context"); 734 735 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 736 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 737 (r = sshpkt_get_end(ssh)) != 0) 738 goto done; 739 740 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 741 debug_f("server sent unknown pkalg %s", pkalg); 742 goto done; 743 } 744 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 745 debug_r(r, "no key from blob. pkalg %s", pkalg); 746 goto done; 747 } 748 if (key->type != pktype) { 749 error("input_userauth_pk_ok: type mismatch " 750 "for decoded key (received %d, expected %d)", 751 key->type, pktype); 752 goto done; 753 } 754 755 /* 756 * search keys in the reverse order, because last candidate has been 757 * moved to the end of the queue. this also avoids confusion by 758 * duplicate keys 759 */ 760 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 761 if (sshkey_equal(key, id->key)) { 762 found = 1; 763 break; 764 } 765 } 766 if (!found || id == NULL) { 767 fp = sshkey_fingerprint(key, options.fingerprint_hash, 768 SSH_FP_DEFAULT); 769 error_f("server replied with unknown key: %s %s", 770 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 771 goto done; 772 } 773 ident = format_identity(id); 774 debug("Server accepts key: %s", ident); 775 sent = sign_and_send_pubkey(ssh, id); 776 r = 0; 777 done: 778 sshkey_free(key); 779 free(ident); 780 free(fp); 781 free(pkalg); 782 free(pkblob); 783 784 /* try another method if we did not send a packet */ 785 if (r == 0 && sent == 0) 786 userauth(ssh, NULL); 787 return r; 788 } 789 790 #ifdef GSSAPI 791 static int 792 userauth_gssapi(struct ssh *ssh) 793 { 794 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 795 Gssctxt *gssctxt = NULL; 796 OM_uint32 min; 797 int r, ok = 0; 798 gss_OID mech = NULL; 799 800 /* Try one GSSAPI method at a time, rather than sending them all at 801 * once. */ 802 803 if (authctxt->gss_supported_mechs == NULL) 804 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 805 806 /* Check to see whether the mechanism is usable before we offer it */ 807 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 808 !ok) { 809 mech = &authctxt->gss_supported_mechs-> 810 elements[authctxt->mech_tried]; 811 /* My DER encoding requires length<128 */ 812 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 813 mech, authctxt->host)) { 814 ok = 1; /* Mechanism works */ 815 } else { 816 authctxt->mech_tried++; 817 } 818 } 819 820 if (!ok || mech == NULL) 821 return 0; 822 823 authctxt->methoddata=(void *)gssctxt; 824 825 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 826 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 827 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 828 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 829 (r = sshpkt_put_u32(ssh, 1)) != 0 || 830 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 831 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 832 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 833 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 834 (r = sshpkt_send(ssh)) != 0) 835 fatal_fr(r, "send packet"); 836 837 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 838 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 839 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 840 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 841 842 authctxt->mech_tried++; /* Move along to next candidate */ 843 844 return 1; 845 } 846 847 static void 848 userauth_gssapi_cleanup(struct ssh *ssh) 849 { 850 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 851 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 852 853 ssh_gssapi_delete_ctx(&gssctxt); 854 authctxt->methoddata = NULL; 855 856 free(authctxt->gss_supported_mechs); 857 authctxt->gss_supported_mechs = NULL; 858 } 859 860 static OM_uint32 861 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 862 { 863 Authctxt *authctxt = ssh->authctxt; 864 Gssctxt *gssctxt = authctxt->methoddata; 865 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 866 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 867 gss_buffer_desc gssbuf; 868 OM_uint32 status, ms, flags; 869 int r; 870 871 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 872 recv_tok, &send_tok, &flags); 873 874 if (send_tok.length > 0) { 875 u_char type = GSS_ERROR(status) ? 876 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 877 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 878 879 if ((r = sshpkt_start(ssh, type)) != 0 || 880 (r = sshpkt_put_string(ssh, send_tok.value, 881 send_tok.length)) != 0 || 882 (r = sshpkt_send(ssh)) != 0) 883 fatal_fr(r, "send %u packet", type); 884 885 gss_release_buffer(&ms, &send_tok); 886 } 887 888 if (status == GSS_S_COMPLETE) { 889 /* send either complete or MIC, depending on mechanism */ 890 if (!(flags & GSS_C_INTEG_FLAG)) { 891 if ((r = sshpkt_start(ssh, 892 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 893 (r = sshpkt_send(ssh)) != 0) 894 fatal_fr(r, "send completion"); 895 } else { 896 struct sshbuf *b; 897 898 if ((b = sshbuf_new()) == NULL) 899 fatal_f("sshbuf_new failed"); 900 ssh_gssapi_buildmic(b, authctxt->server_user, 901 authctxt->service, "gssapi-with-mic", 902 ssh->kex->session_id); 903 904 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 905 fatal_f("sshbuf_mutable_ptr failed"); 906 gssbuf.length = sshbuf_len(b); 907 908 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 909 910 if (!GSS_ERROR(status)) { 911 if ((r = sshpkt_start(ssh, 912 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 913 (r = sshpkt_put_string(ssh, mic.value, 914 mic.length)) != 0 || 915 (r = sshpkt_send(ssh)) != 0) 916 fatal_fr(r, "send MIC"); 917 } 918 919 sshbuf_free(b); 920 gss_release_buffer(&ms, &mic); 921 } 922 } 923 924 return status; 925 } 926 927 static int 928 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 929 { 930 Authctxt *authctxt = ssh->authctxt; 931 Gssctxt *gssctxt; 932 size_t oidlen; 933 u_char *oidv = NULL; 934 int r; 935 936 if (authctxt == NULL) 937 fatal("input_gssapi_response: no authentication context"); 938 gssctxt = authctxt->methoddata; 939 940 /* Setup our OID */ 941 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 942 goto done; 943 944 if (oidlen <= 2 || 945 oidv[0] != SSH_GSS_OIDTYPE || 946 oidv[1] != oidlen - 2) { 947 debug("Badly encoded mechanism OID received"); 948 userauth(ssh, NULL); 949 goto ok; 950 } 951 952 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 953 fatal("Server returned different OID than expected"); 954 955 if ((r = sshpkt_get_end(ssh)) != 0) 956 goto done; 957 958 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 959 /* Start again with next method on list */ 960 debug("Trying to start again"); 961 userauth(ssh, NULL); 962 goto ok; 963 } 964 ok: 965 r = 0; 966 done: 967 free(oidv); 968 return r; 969 } 970 971 static int 972 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 973 { 974 Authctxt *authctxt = ssh->authctxt; 975 gss_buffer_desc recv_tok; 976 u_char *p = NULL; 977 size_t len; 978 OM_uint32 status; 979 int r; 980 981 if (authctxt == NULL) 982 fatal("input_gssapi_response: no authentication context"); 983 984 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 985 (r = sshpkt_get_end(ssh)) != 0) 986 goto out; 987 988 recv_tok.value = p; 989 recv_tok.length = len; 990 status = process_gssapi_token(ssh, &recv_tok); 991 992 /* Start again with the next method in the list */ 993 if (GSS_ERROR(status)) { 994 userauth(ssh, NULL); 995 /* ok */ 996 } 997 r = 0; 998 out: 999 free(p); 1000 return r; 1001 } 1002 1003 static int 1004 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 1005 { 1006 Authctxt *authctxt = ssh->authctxt; 1007 Gssctxt *gssctxt; 1008 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 1009 gss_buffer_desc recv_tok; 1010 OM_uint32 ms; 1011 u_char *p = NULL; 1012 size_t len; 1013 int r; 1014 1015 if (authctxt == NULL) 1016 fatal("input_gssapi_response: no authentication context"); 1017 gssctxt = authctxt->methoddata; 1018 1019 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1020 (r = sshpkt_get_end(ssh)) != 0) { 1021 free(p); 1022 return r; 1023 } 1024 1025 /* Stick it into GSSAPI and see what it says */ 1026 recv_tok.value = p; 1027 recv_tok.length = len; 1028 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1029 &recv_tok, &send_tok, NULL); 1030 free(p); 1031 gss_release_buffer(&ms, &send_tok); 1032 1033 /* Server will be returning a failed packet after this one */ 1034 return 0; 1035 } 1036 1037 static int 1038 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1039 { 1040 char *msg = NULL; 1041 char *lang = NULL; 1042 int r; 1043 1044 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1045 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1046 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1047 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1048 goto out; 1049 r = sshpkt_get_end(ssh); 1050 debug("Server GSSAPI Error:\n%s", msg); 1051 out: 1052 free(msg); 1053 free(lang); 1054 return r; 1055 } 1056 #endif /* GSSAPI */ 1057 1058 static int 1059 userauth_none(struct ssh *ssh) 1060 { 1061 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1062 int r; 1063 1064 /* initial userauth request */ 1065 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1066 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1067 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1068 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1069 (r = sshpkt_send(ssh)) != 0) 1070 fatal_fr(r, "send packet"); 1071 return 1; 1072 } 1073 1074 static int 1075 userauth_passwd(struct ssh *ssh) 1076 { 1077 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1078 char *password, *prompt = NULL; 1079 const char *host = options.host_key_alias ? options.host_key_alias : 1080 authctxt->host; 1081 int r; 1082 1083 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1084 return 0; 1085 1086 if (authctxt->attempt_passwd != 1) 1087 error("Permission denied, please try again."); 1088 1089 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1090 password = read_passphrase(prompt, 0); 1091 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1092 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1093 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1094 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1095 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1096 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1097 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1098 (r = sshpkt_send(ssh)) != 0) 1099 fatal_fr(r, "send packet"); 1100 1101 free(prompt); 1102 if (password != NULL) 1103 freezero(password, strlen(password)); 1104 1105 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1106 &input_userauth_passwd_changereq); 1107 1108 return 1; 1109 } 1110 1111 /* 1112 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1113 */ 1114 static int 1115 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1116 { 1117 Authctxt *authctxt = ssh->authctxt; 1118 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1119 char prompt[256]; 1120 const char *host; 1121 int r; 1122 1123 debug2("input_userauth_passwd_changereq"); 1124 1125 if (authctxt == NULL) 1126 fatal("input_userauth_passwd_changereq: " 1127 "no authentication context"); 1128 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1129 1130 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1131 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1132 goto out; 1133 if (strlen(info) > 0) 1134 logit("%s", info); 1135 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1136 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1137 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1138 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1139 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1140 goto out; 1141 1142 snprintf(prompt, sizeof(prompt), 1143 "Enter %.30s@%.128s's old password: ", 1144 authctxt->server_user, host); 1145 password = read_passphrase(prompt, 0); 1146 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1147 goto out; 1148 1149 freezero(password, strlen(password)); 1150 password = NULL; 1151 while (password == NULL) { 1152 snprintf(prompt, sizeof(prompt), 1153 "Enter %.30s@%.128s's new password: ", 1154 authctxt->server_user, host); 1155 password = read_passphrase(prompt, RP_ALLOW_EOF); 1156 if (password == NULL) { 1157 /* bail out */ 1158 r = 0; 1159 goto out; 1160 } 1161 snprintf(prompt, sizeof(prompt), 1162 "Retype %.30s@%.128s's new password: ", 1163 authctxt->server_user, host); 1164 retype = read_passphrase(prompt, 0); 1165 if (strcmp(password, retype) != 0) { 1166 freezero(password, strlen(password)); 1167 logit("Mismatch; try again, EOF to quit."); 1168 password = NULL; 1169 } 1170 freezero(retype, strlen(retype)); 1171 } 1172 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1173 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1174 (r = sshpkt_send(ssh)) != 0) 1175 goto out; 1176 1177 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1178 &input_userauth_passwd_changereq); 1179 r = 0; 1180 out: 1181 if (password) 1182 freezero(password, strlen(password)); 1183 free(info); 1184 free(lang); 1185 return r; 1186 } 1187 1188 /* 1189 * Select an algorithm for publickey signatures. 1190 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1191 * 1192 * Call with ssh==NULL to ignore server-sig-algs extension list and 1193 * only attempt with the key's base signature type. 1194 */ 1195 static char * 1196 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1197 { 1198 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1199 const char *server_sig_algs; 1200 1201 /* 1202 * The signature algorithm will only differ from the key algorithm 1203 * for RSA keys/certs and when the server advertises support for 1204 * newer (SHA2) algorithms. 1205 */ 1206 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1207 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1208 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1209 /* Filter base key signature alg against our configuration */ 1210 return match_list(sshkey_ssh_name(key), 1211 options.pubkey_accepted_algos, NULL); 1212 } 1213 1214 /* 1215 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1216 * fails to advertise it via SSH2_MSG_EXT_INFO. 1217 */ 1218 server_sig_algs = ssh->kex->server_sig_algs; 1219 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1220 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1221 1222 /* 1223 * For RSA keys/certs, since these might have a different sig type: 1224 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1225 * that also appears in the supported signature algorithms list from 1226 * the server. 1227 */ 1228 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1229 while ((cp = strsep(&allowed, ",")) != NULL) { 1230 if (sshkey_type_from_name(cp) != key->type) 1231 continue; 1232 tmp = match_list(sshkey_sigalg_by_name(cp), 1233 server_sig_algs, NULL); 1234 if (tmp != NULL) 1235 alg = xstrdup(cp); 1236 free(tmp); 1237 if (alg != NULL) 1238 break; 1239 } 1240 free(oallowed); 1241 return alg; 1242 } 1243 1244 static int 1245 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1246 const u_char *data, size_t datalen, u_int compat, const char *alg) 1247 { 1248 struct sshkey *sign_key = NULL, *prv = NULL; 1249 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1250 struct notifier_ctx *notifier = NULL; 1251 char *fp = NULL, *pin = NULL, *prompt = NULL; 1252 1253 *sigp = NULL; 1254 *lenp = 0; 1255 1256 /* The agent supports this key. */ 1257 if (id->key != NULL && id->agent_fd != -1) { 1258 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1259 data, datalen, alg, compat); 1260 } 1261 1262 /* 1263 * We have already loaded the private key or the private key is 1264 * stored in external hardware. 1265 */ 1266 if (id->key != NULL && 1267 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1268 sign_key = id->key; 1269 is_agent = 1; 1270 } else { 1271 /* Load the private key from the file. */ 1272 if ((prv = load_identity_file(id)) == NULL) 1273 return SSH_ERR_KEY_NOT_FOUND; 1274 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1275 error_f("private key %s contents do not match public", 1276 id->filename); 1277 r = SSH_ERR_KEY_NOT_FOUND; 1278 goto out; 1279 } 1280 sign_key = prv; 1281 } 1282 retry_pin: 1283 /* Prompt for touch for non-agent FIDO keys that request UP */ 1284 if (!is_agent && sshkey_is_sk(sign_key) && 1285 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1286 /* XXX should batch mode just skip these? */ 1287 if ((fp = sshkey_fingerprint(sign_key, 1288 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1289 fatal_f("fingerprint failed"); 1290 notifier = notify_start(options.batch_mode, 1291 "Confirm user presence for key %s %s", 1292 sshkey_type(sign_key), fp); 1293 free(fp); 1294 } 1295 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1296 alg, options.sk_provider, pin, compat)) != 0) { 1297 debug_fr(r, "sshkey_sign"); 1298 if (!retried && pin == NULL && !is_agent && 1299 sshkey_is_sk(sign_key) && 1300 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1301 notify_complete(notifier, NULL); 1302 notifier = NULL; 1303 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1304 sshkey_type(sign_key), id->filename); 1305 pin = read_passphrase(prompt, 0); 1306 retried = 1; 1307 goto retry_pin; 1308 } 1309 goto out; 1310 } 1311 1312 /* 1313 * PKCS#11 tokens may not support all signature algorithms, 1314 * so check what we get back. 1315 */ 1316 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1317 debug_fr(r, "sshkey_check_sigtype"); 1318 goto out; 1319 } 1320 /* success */ 1321 r = 0; 1322 out: 1323 free(prompt); 1324 if (pin != NULL) 1325 freezero(pin, strlen(pin)); 1326 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1327 sshkey_free(prv); 1328 return r; 1329 } 1330 1331 static int 1332 id_filename_matches(Identity *id, Identity *private_id) 1333 { 1334 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1335 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1336 size_t i, slen; 1337 1338 if (strcmp(id->filename, private_id->filename) == 0) 1339 return 1; 1340 for (i = 0; suffixes[i]; i++) { 1341 slen = strlen(suffixes[i]); 1342 if (len > slen && plen == len - slen && 1343 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1344 memcmp(id->filename, private_id->filename, plen) == 0) 1345 return 1; 1346 } 1347 return 0; 1348 } 1349 1350 static int 1351 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1352 { 1353 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1354 struct sshbuf *b = NULL; 1355 Identity *private_id, *sign_id = NULL; 1356 u_char *signature = NULL; 1357 size_t slen = 0, skip = 0; 1358 int r, fallback_sigtype, sent = 0; 1359 char *alg = NULL, *fp = NULL; 1360 const char *loc = "", *method = "publickey"; 1361 int hostbound = 0; 1362 1363 /* prefer host-bound pubkey signatures if supported by server */ 1364 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1365 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1366 hostbound = 1; 1367 method = "publickey-hostbound-v00@openssh.com"; 1368 } 1369 1370 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1371 SSH_FP_DEFAULT)) == NULL) 1372 return 0; 1373 1374 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1375 1376 /* 1377 * If the key is an certificate, try to find a matching private key 1378 * and use it to complete the signature. 1379 * If no such private key exists, fall back to trying the certificate 1380 * key itself in case it has a private half already loaded. 1381 * This will try to set sign_id to the private key that will perform 1382 * the signature. 1383 */ 1384 if (sshkey_is_cert(id->key)) { 1385 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1386 if (sshkey_equal_public(id->key, private_id->key) && 1387 id->key->type != private_id->key->type) { 1388 sign_id = private_id; 1389 break; 1390 } 1391 } 1392 /* 1393 * Exact key matches are preferred, but also allow 1394 * filename matches for non-PKCS#11/agent keys that 1395 * didn't load public keys. This supports the case 1396 * of keeping just a private key file and public 1397 * certificate on disk. 1398 */ 1399 if (sign_id == NULL && 1400 !id->isprivate && id->agent_fd == -1 && 1401 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1402 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1403 if (private_id->key == NULL && 1404 id_filename_matches(id, private_id)) { 1405 sign_id = private_id; 1406 break; 1407 } 1408 } 1409 } 1410 if (sign_id != NULL) { 1411 debug2_f("using private key \"%s\"%s for " 1412 "certificate", sign_id->filename, 1413 sign_id->agent_fd != -1 ? " from agent" : ""); 1414 } else { 1415 debug_f("no separate private key for certificate " 1416 "\"%s\"", id->filename); 1417 } 1418 } 1419 1420 /* 1421 * If the above didn't select another identity to do the signing 1422 * then default to the one we started with. 1423 */ 1424 if (sign_id == NULL) 1425 sign_id = id; 1426 1427 /* assemble and sign data */ 1428 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1429 free(alg); 1430 slen = 0; 1431 signature = NULL; 1432 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1433 id->key)) == NULL) { 1434 error_f("no mutual signature supported"); 1435 goto out; 1436 } 1437 debug3_f("signing using %s %s", alg, fp); 1438 1439 sshbuf_free(b); 1440 if ((b = sshbuf_new()) == NULL) 1441 fatal_f("sshbuf_new failed"); 1442 if (ssh->compat & SSH_OLD_SESSIONID) { 1443 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1444 fatal_fr(r, "sshbuf_putb"); 1445 } else { 1446 if ((r = sshbuf_put_stringb(b, 1447 ssh->kex->session_id)) != 0) 1448 fatal_fr(r, "sshbuf_put_stringb"); 1449 } 1450 skip = sshbuf_len(b); 1451 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1452 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1453 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1454 (r = sshbuf_put_cstring(b, method)) != 0 || 1455 (r = sshbuf_put_u8(b, 1)) != 0 || 1456 (r = sshbuf_put_cstring(b, alg)) != 0 || 1457 (r = sshkey_puts(id->key, b)) != 0) { 1458 fatal_fr(r, "assemble signed data"); 1459 } 1460 if (hostbound) { 1461 if (ssh->kex->initial_hostkey == NULL) { 1462 fatal_f("internal error: initial hostkey " 1463 "not recorded"); 1464 } 1465 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1466 fatal_fr(r, "assemble %s hostkey", method); 1467 } 1468 /* generate signature */ 1469 r = identity_sign(sign_id, &signature, &slen, 1470 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1471 if (r == 0) 1472 break; 1473 else if (r == SSH_ERR_KEY_NOT_FOUND) 1474 goto out; /* soft failure */ 1475 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1476 !fallback_sigtype) { 1477 if (sign_id->agent_fd != -1) 1478 loc = "agent "; 1479 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1480 loc = "token "; 1481 logit("%skey %s %s returned incorrect signature type", 1482 loc, sshkey_type(id->key), fp); 1483 continue; 1484 } 1485 error_fr(r, "signing failed for %s \"%s\"%s", 1486 sshkey_type(sign_id->key), sign_id->filename, 1487 id->agent_fd != -1 ? " from agent" : ""); 1488 goto out; 1489 } 1490 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1491 fatal_f("no signature"); 1492 1493 /* append signature */ 1494 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1495 fatal_fr(r, "append signature"); 1496 1497 #ifdef DEBUG_PK 1498 sshbuf_dump(b, stderr); 1499 #endif 1500 /* skip session id and packet type */ 1501 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1502 fatal_fr(r, "consume"); 1503 1504 /* put remaining data from buffer into packet */ 1505 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1506 (r = sshpkt_putb(ssh, b)) != 0 || 1507 (r = sshpkt_send(ssh)) != 0) 1508 fatal_fr(r, "enqueue request"); 1509 1510 /* success */ 1511 sent = 1; 1512 1513 out: 1514 free(fp); 1515 free(alg); 1516 sshbuf_free(b); 1517 freezero(signature, slen); 1518 return sent; 1519 } 1520 1521 static int 1522 send_pubkey_test(struct ssh *ssh, Identity *id) 1523 { 1524 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1525 u_char *blob = NULL; 1526 char *alg = NULL; 1527 size_t bloblen; 1528 u_int have_sig = 0; 1529 int sent = 0, r; 1530 1531 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1532 debug_f("no mutual signature algorithm"); 1533 goto out; 1534 } 1535 1536 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1537 /* we cannot handle this key */ 1538 debug3_f("cannot handle key"); 1539 goto out; 1540 } 1541 /* register callback for USERAUTH_PK_OK message */ 1542 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1543 1544 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1545 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1546 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1547 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1548 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1549 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1550 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1551 (r = sshpkt_send(ssh)) != 0) 1552 fatal_fr(r, "send packet"); 1553 sent = 1; 1554 1555 out: 1556 free(alg); 1557 free(blob); 1558 return sent; 1559 } 1560 1561 static struct sshkey * 1562 load_identity_file(Identity *id) 1563 { 1564 struct sshkey *private = NULL; 1565 char prompt[300], *passphrase, *comment; 1566 int r, quit = 0, i; 1567 struct stat st; 1568 1569 if (stat(id->filename, &st) == -1) { 1570 do_log2(id->userprovided ? 1571 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1572 "no such identity: %s: %s", id->filename, strerror(errno)); 1573 return NULL; 1574 } 1575 snprintf(prompt, sizeof prompt, 1576 "Enter passphrase for key '%.100s': ", id->filename); 1577 for (i = 0; i <= options.number_of_password_prompts; i++) { 1578 if (i == 0) 1579 passphrase = xstrdup(""); 1580 else { 1581 passphrase = read_passphrase(prompt, 0); 1582 if (*passphrase == '\0') { 1583 debug2("no passphrase given, try next key"); 1584 free(passphrase); 1585 break; 1586 } 1587 } 1588 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1589 passphrase, &private, &comment))) { 1590 case 0: 1591 break; 1592 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1593 if (options.batch_mode) { 1594 quit = 1; 1595 break; 1596 } 1597 if (i != 0) 1598 debug2("bad passphrase given, try again..."); 1599 break; 1600 case SSH_ERR_SYSTEM_ERROR: 1601 if (errno == ENOENT) { 1602 debug2_r(r, "Load key \"%s\"", id->filename); 1603 quit = 1; 1604 break; 1605 } 1606 /* FALLTHROUGH */ 1607 default: 1608 error_r(r, "Load key \"%s\"", id->filename); 1609 quit = 1; 1610 break; 1611 } 1612 if (private != NULL && sshkey_is_sk(private) && 1613 options.sk_provider == NULL) { 1614 debug("key \"%s\" is an authenticator-hosted key, " 1615 "but no provider specified", id->filename); 1616 sshkey_free(private); 1617 private = NULL; 1618 quit = 1; 1619 } 1620 if (!quit && (r = sshkey_check_rsa_length(private, 1621 options.required_rsa_size)) != 0) { 1622 debug_fr(r, "Skipping key %s", id->filename); 1623 sshkey_free(private); 1624 private = NULL; 1625 quit = 1; 1626 } 1627 if (!quit && private != NULL && id->agent_fd == -1 && 1628 !(id->key && id->isprivate)) 1629 maybe_add_key_to_agent(id->filename, private, comment, 1630 passphrase); 1631 if (i > 0) 1632 freezero(passphrase, strlen(passphrase)); 1633 free(comment); 1634 if (private != NULL || quit) 1635 break; 1636 } 1637 return private; 1638 } 1639 1640 static int 1641 key_type_allowed_by_config(struct sshkey *key) 1642 { 1643 if (match_pattern_list(sshkey_ssh_name(key), 1644 options.pubkey_accepted_algos, 0) == 1) 1645 return 1; 1646 1647 /* RSA keys/certs might be allowed by alternate signature types */ 1648 switch (key->type) { 1649 case KEY_RSA: 1650 if (match_pattern_list("rsa-sha2-512", 1651 options.pubkey_accepted_algos, 0) == 1) 1652 return 1; 1653 if (match_pattern_list("rsa-sha2-256", 1654 options.pubkey_accepted_algos, 0) == 1) 1655 return 1; 1656 break; 1657 case KEY_RSA_CERT: 1658 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1659 options.pubkey_accepted_algos, 0) == 1) 1660 return 1; 1661 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1662 options.pubkey_accepted_algos, 0) == 1) 1663 return 1; 1664 break; 1665 } 1666 return 0; 1667 } 1668 1669 /* obtain a list of keys from the agent */ 1670 static int 1671 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1672 struct ssh_identitylist **idlistp) 1673 { 1674 int r, agent_fd; 1675 struct ssh_identitylist *idlist; 1676 1677 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1678 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1679 debug_fr(r, "ssh_get_authentication_socket"); 1680 return r; 1681 } 1682 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1683 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1684 debug_f("bound agent to hostkey"); 1685 else 1686 debug2_fr(r, "ssh_agent_bind_hostkey"); 1687 1688 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1689 debug_fr(r, "ssh_fetch_identitylist"); 1690 close(agent_fd); 1691 return r; 1692 } 1693 /* success */ 1694 *agent_fdp = agent_fd; 1695 *idlistp = idlist; 1696 debug_f("agent returned %zu keys", idlist->nkeys); 1697 return 0; 1698 } 1699 1700 /* 1701 * try keys in the following order: 1702 * 1. certificates listed in the config file 1703 * 2. other input certificates 1704 * 3. agent keys that are found in the config file 1705 * 4. other agent keys 1706 * 5. keys that are only listed in the config file 1707 */ 1708 static void 1709 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1710 { 1711 struct identity *id, *id2, *tmp; 1712 struct idlist agent, files, *preferred; 1713 struct sshkey *key; 1714 int agent_fd = -1, i, r, found; 1715 size_t j; 1716 struct ssh_identitylist *idlist; 1717 char *ident; 1718 1719 TAILQ_INIT(&agent); /* keys from the agent */ 1720 TAILQ_INIT(&files); /* keys from the config file */ 1721 preferred = &authctxt->keys; 1722 TAILQ_INIT(preferred); /* preferred order of keys */ 1723 1724 /* list of keys stored in the filesystem and PKCS#11 */ 1725 for (i = 0; i < options.num_identity_files; i++) { 1726 key = options.identity_keys[i]; 1727 if (key && key->cert && 1728 key->cert->type != SSH2_CERT_TYPE_USER) { 1729 debug_f("ignoring certificate %s: not a user " 1730 "certificate", options.identity_files[i]); 1731 continue; 1732 } 1733 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1734 debug_f("ignoring authenticator-hosted key %s as no " 1735 "SecurityKeyProvider has been specified", 1736 options.identity_files[i]); 1737 continue; 1738 } 1739 options.identity_keys[i] = NULL; 1740 id = xcalloc(1, sizeof(*id)); 1741 id->agent_fd = -1; 1742 id->key = key; 1743 id->filename = xstrdup(options.identity_files[i]); 1744 id->userprovided = options.identity_file_userprovided[i]; 1745 TAILQ_INSERT_TAIL(&files, id, next); 1746 } 1747 /* list of certificates specified by user */ 1748 for (i = 0; i < options.num_certificate_files; i++) { 1749 key = options.certificates[i]; 1750 if (!sshkey_is_cert(key) || key->cert == NULL || 1751 key->cert->type != SSH2_CERT_TYPE_USER) { 1752 debug_f("ignoring certificate %s: not a user " 1753 "certificate", options.identity_files[i]); 1754 continue; 1755 } 1756 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1757 debug_f("ignoring authenticator-hosted key " 1758 "certificate %s as no " 1759 "SecurityKeyProvider has been specified", 1760 options.identity_files[i]); 1761 continue; 1762 } 1763 id = xcalloc(1, sizeof(*id)); 1764 id->agent_fd = -1; 1765 id->key = key; 1766 id->filename = xstrdup(options.certificate_files[i]); 1767 id->userprovided = options.certificate_file_userprovided[i]; 1768 TAILQ_INSERT_TAIL(preferred, id, next); 1769 } 1770 /* list of keys supported by the agent */ 1771 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1772 for (j = 0; j < idlist->nkeys; j++) { 1773 if ((r = sshkey_check_rsa_length(idlist->keys[j], 1774 options.required_rsa_size)) != 0) { 1775 debug_fr(r, "ignoring %s agent key", 1776 sshkey_ssh_name(idlist->keys[j])); 1777 continue; 1778 } 1779 found = 0; 1780 TAILQ_FOREACH(id, &files, next) { 1781 /* 1782 * agent keys from the config file are 1783 * preferred 1784 */ 1785 if (sshkey_equal(idlist->keys[j], id->key)) { 1786 TAILQ_REMOVE(&files, id, next); 1787 TAILQ_INSERT_TAIL(preferred, id, next); 1788 id->agent_fd = agent_fd; 1789 found = 1; 1790 break; 1791 } 1792 } 1793 if (!found && !options.identities_only) { 1794 id = xcalloc(1, sizeof(*id)); 1795 /* XXX "steals" key/comment from idlist */ 1796 id->key = idlist->keys[j]; 1797 id->filename = idlist->comments[j]; 1798 idlist->keys[j] = NULL; 1799 idlist->comments[j] = NULL; 1800 id->agent_fd = agent_fd; 1801 TAILQ_INSERT_TAIL(&agent, id, next); 1802 } 1803 } 1804 ssh_free_identitylist(idlist); 1805 /* append remaining agent keys */ 1806 TAILQ_CONCAT(preferred, &agent, next); 1807 authctxt->agent_fd = agent_fd; 1808 } 1809 /* Prefer PKCS11 keys that are explicitly listed */ 1810 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1811 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1812 continue; 1813 found = 0; 1814 TAILQ_FOREACH(id2, &files, next) { 1815 if (id2->key == NULL || 1816 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1817 continue; 1818 if (sshkey_equal(id->key, id2->key)) { 1819 TAILQ_REMOVE(&files, id, next); 1820 TAILQ_INSERT_TAIL(preferred, id, next); 1821 found = 1; 1822 break; 1823 } 1824 } 1825 /* If IdentitiesOnly set and key not found then don't use it */ 1826 if (!found && options.identities_only) { 1827 TAILQ_REMOVE(&files, id, next); 1828 freezero(id, sizeof(*id)); 1829 } 1830 } 1831 /* append remaining keys from the config file */ 1832 TAILQ_CONCAT(preferred, &files, next); 1833 /* finally, filter by PubkeyAcceptedAlgorithms */ 1834 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1835 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1836 debug("Skipping %s key %s - " 1837 "corresponding algo not in PubkeyAcceptedAlgorithms", 1838 sshkey_ssh_name(id->key), id->filename); 1839 TAILQ_REMOVE(preferred, id, next); 1840 sshkey_free(id->key); 1841 free(id->filename); 1842 memset(id, 0, sizeof(*id)); 1843 continue; 1844 } 1845 } 1846 /* List the keys we plan on using */ 1847 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1848 ident = format_identity(id); 1849 debug("Will attempt key: %s", ident); 1850 free(ident); 1851 } 1852 debug2_f("done"); 1853 } 1854 1855 static void 1856 pubkey_cleanup(struct ssh *ssh) 1857 { 1858 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1859 Identity *id; 1860 1861 if (authctxt->agent_fd != -1) { 1862 ssh_close_authentication_socket(authctxt->agent_fd); 1863 authctxt->agent_fd = -1; 1864 } 1865 for (id = TAILQ_FIRST(&authctxt->keys); id; 1866 id = TAILQ_FIRST(&authctxt->keys)) { 1867 TAILQ_REMOVE(&authctxt->keys, id, next); 1868 sshkey_free(id->key); 1869 free(id->filename); 1870 free(id); 1871 } 1872 } 1873 1874 static void 1875 pubkey_reset(Authctxt *authctxt) 1876 { 1877 Identity *id; 1878 1879 TAILQ_FOREACH(id, &authctxt->keys, next) 1880 id->tried = 0; 1881 } 1882 1883 static int 1884 userauth_pubkey(struct ssh *ssh) 1885 { 1886 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1887 Identity *id; 1888 int sent = 0; 1889 char *ident; 1890 1891 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1892 if (id->tried++) 1893 return (0); 1894 /* move key to the end of the queue */ 1895 TAILQ_REMOVE(&authctxt->keys, id, next); 1896 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1897 /* 1898 * send a test message if we have the public key. for 1899 * encrypted keys we cannot do this and have to load the 1900 * private key instead 1901 */ 1902 if (id->key != NULL) { 1903 if (id->key != NULL) { 1904 ident = format_identity(id); 1905 debug("Offering public key: %s", ident); 1906 free(ident); 1907 sent = send_pubkey_test(ssh, id); 1908 } 1909 } else { 1910 debug("Trying private key: %s", id->filename); 1911 id->key = load_identity_file(id); 1912 if (id->key != NULL) { 1913 if (id->key != NULL) { 1914 id->isprivate = 1; 1915 sent = sign_and_send_pubkey(ssh, id); 1916 } 1917 sshkey_free(id->key); 1918 id->key = NULL; 1919 id->isprivate = 0; 1920 } 1921 } 1922 if (sent) 1923 return (sent); 1924 } 1925 return (0); 1926 } 1927 1928 /* 1929 * Send userauth request message specifying keyboard-interactive method. 1930 */ 1931 static int 1932 userauth_kbdint(struct ssh *ssh) 1933 { 1934 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1935 int r; 1936 1937 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1938 return 0; 1939 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1940 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1941 debug3("userauth_kbdint: disable: no info_req_seen"); 1942 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1943 return 0; 1944 } 1945 1946 debug2("userauth_kbdint"); 1947 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1948 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1949 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1950 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1951 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1952 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1953 options.kbd_interactive_devices : "")) != 0 || 1954 (r = sshpkt_send(ssh)) != 0) 1955 fatal_fr(r, "send packet"); 1956 1957 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1958 return 1; 1959 } 1960 1961 /* 1962 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1963 */ 1964 static int 1965 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1966 { 1967 Authctxt *authctxt = ssh->authctxt; 1968 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1969 char *display_prompt = NULL, *response = NULL; 1970 u_char echo = 0; 1971 u_int num_prompts, i; 1972 int r; 1973 1974 debug2_f("entering"); 1975 1976 if (authctxt == NULL) 1977 fatal_f("no authentication context"); 1978 1979 authctxt->info_req_seen = 1; 1980 1981 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1982 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1983 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1984 goto out; 1985 if (strlen(name) > 0) 1986 logit("%s", name); 1987 if (strlen(inst) > 0) 1988 logit("%s", inst); 1989 1990 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1991 goto out; 1992 /* 1993 * Begin to build info response packet based on prompts requested. 1994 * We commit to providing the correct number of responses, so if 1995 * further on we run into a problem that prevents this, we have to 1996 * be sure and clean this up and send a correct error response. 1997 */ 1998 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1999 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 2000 goto out; 2001 2002 debug2_f("num_prompts %d", num_prompts); 2003 for (i = 0; i < num_prompts; i++) { 2004 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 2005 (r = sshpkt_get_u8(ssh, &echo)) != 0) 2006 goto out; 2007 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 2008 authctxt->server_user, options.host_key_alias ? 2009 options.host_key_alias : authctxt->host, prompt) == -1) 2010 fatal_f("asmprintf failed"); 2011 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 2012 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 2013 goto out; 2014 freezero(response, strlen(response)); 2015 free(prompt); 2016 free(display_prompt); 2017 display_prompt = response = prompt = NULL; 2018 } 2019 /* done with parsing incoming message. */ 2020 if ((r = sshpkt_get_end(ssh)) != 0 || 2021 (r = sshpkt_add_padding(ssh, 64)) != 0) 2022 goto out; 2023 r = sshpkt_send(ssh); 2024 out: 2025 if (response) 2026 freezero(response, strlen(response)); 2027 free(prompt); 2028 free(display_prompt); 2029 free(name); 2030 free(inst); 2031 free(lang); 2032 return r; 2033 } 2034 2035 static int 2036 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2037 const u_char *data, size_t datalen) 2038 { 2039 struct sshbuf *b; 2040 struct stat st; 2041 pid_t pid; 2042 int r, to[2], from[2], status; 2043 int sock = ssh_packet_get_connection_in(ssh); 2044 u_char rversion = 0, version = 2; 2045 void (*osigchld)(int); 2046 2047 *sigp = NULL; 2048 *lenp = 0; 2049 2050 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2051 error_f("not installed: %s", strerror(errno)); 2052 return -1; 2053 } 2054 if (fflush(stdout) != 0) { 2055 error_f("fflush: %s", strerror(errno)); 2056 return -1; 2057 } 2058 if (pipe(to) == -1) { 2059 error_f("pipe: %s", strerror(errno)); 2060 return -1; 2061 } 2062 if (pipe(from) == -1) { 2063 error_f("pipe: %s", strerror(errno)); 2064 return -1; 2065 } 2066 if ((pid = fork()) == -1) { 2067 error_f("fork: %s", strerror(errno)); 2068 return -1; 2069 } 2070 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2071 if (pid == 0) { 2072 close(from[0]); 2073 if (dup2(from[1], STDOUT_FILENO) == -1) 2074 fatal_f("dup2: %s", strerror(errno)); 2075 close(to[1]); 2076 if (dup2(to[0], STDIN_FILENO) == -1) 2077 fatal_f("dup2: %s", strerror(errno)); 2078 close(from[1]); 2079 close(to[0]); 2080 if (dup2(sock, STDERR_FILENO + 1) == -1) 2081 fatal_f("dup2: %s", strerror(errno)); 2082 sock = STDERR_FILENO + 1; 2083 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */ 2084 debug3_f("fcntl F_SETFD: %s", strerror(errno)); 2085 closefrom(sock + 1); 2086 2087 debug3_f("[child] pid=%ld, exec %s", 2088 (long)getpid(), _PATH_SSH_KEY_SIGN); 2089 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2090 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2091 strerror(errno)); 2092 } 2093 close(from[1]); 2094 close(to[0]); 2095 sock = STDERR_FILENO + 1; 2096 2097 if ((b = sshbuf_new()) == NULL) 2098 fatal_f("sshbuf_new failed"); 2099 /* send # of sock, data to be signed */ 2100 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2101 (r = sshbuf_put_string(b, data, datalen)) != 0) 2102 fatal_fr(r, "buffer error"); 2103 if (ssh_msg_send(to[1], version, b) == -1) 2104 fatal_f("couldn't send request"); 2105 sshbuf_reset(b); 2106 r = ssh_msg_recv(from[0], b); 2107 close(from[0]); 2108 close(to[1]); 2109 if (r < 0) { 2110 error_f("no reply"); 2111 goto fail; 2112 } 2113 2114 errno = 0; 2115 while (waitpid(pid, &status, 0) == -1) { 2116 if (errno != EINTR) { 2117 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2118 goto fail; 2119 } 2120 } 2121 if (!WIFEXITED(status)) { 2122 error_f("exited abnormally"); 2123 goto fail; 2124 } 2125 if (WEXITSTATUS(status) != 0) { 2126 error_f("exited with status %d", WEXITSTATUS(status)); 2127 goto fail; 2128 } 2129 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2130 error_fr(r, "buffer error"); 2131 goto fail; 2132 } 2133 if (rversion != version) { 2134 error_f("bad version"); 2135 goto fail; 2136 } 2137 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2138 error_fr(r, "buffer error"); 2139 fail: 2140 ssh_signal(SIGCHLD, osigchld); 2141 sshbuf_free(b); 2142 return -1; 2143 } 2144 ssh_signal(SIGCHLD, osigchld); 2145 sshbuf_free(b); 2146 2147 return 0; 2148 } 2149 2150 static int 2151 userauth_hostbased(struct ssh *ssh) 2152 { 2153 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2154 struct sshkey *private = NULL; 2155 struct sshbuf *b = NULL; 2156 u_char *sig = NULL, *keyblob = NULL; 2157 char *fp = NULL, *chost = NULL, *lname = NULL; 2158 size_t siglen = 0, keylen = 0; 2159 int i, r, success = 0; 2160 2161 if (authctxt->ktypes == NULL) { 2162 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2163 authctxt->ktypes = authctxt->oktypes; 2164 } 2165 2166 /* 2167 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2168 * trying each hostkey that matches the type in turn. 2169 */ 2170 for (;;) { 2171 if (authctxt->active_ktype == NULL) 2172 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2173 if (authctxt->active_ktype == NULL || 2174 *authctxt->active_ktype == '\0') 2175 break; 2176 debug3_f("trying key type %s", authctxt->active_ktype); 2177 2178 /* check for a useful key */ 2179 private = NULL; 2180 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2181 if (authctxt->sensitive->keys[i] == NULL || 2182 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2183 continue; 2184 if (!sshkey_match_keyname_to_sigalgs( 2185 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2186 authctxt->active_ktype)) 2187 continue; 2188 /* we take and free the key */ 2189 private = authctxt->sensitive->keys[i]; 2190 authctxt->sensitive->keys[i] = NULL; 2191 break; 2192 } 2193 /* Found one */ 2194 if (private != NULL) 2195 break; 2196 /* No more keys of this type; advance */ 2197 authctxt->active_ktype = NULL; 2198 } 2199 if (private == NULL) { 2200 free(authctxt->oktypes); 2201 authctxt->oktypes = authctxt->ktypes = NULL; 2202 authctxt->active_ktype = NULL; 2203 debug("No more client hostkeys for hostbased authentication."); 2204 goto out; 2205 } 2206 2207 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2208 SSH_FP_DEFAULT)) == NULL) { 2209 error_f("sshkey_fingerprint failed"); 2210 goto out; 2211 } 2212 debug_f("trying hostkey %s %s using sigalg %s", 2213 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2214 2215 /* figure out a name for the client host */ 2216 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2217 if (lname == NULL) { 2218 error_f("cannot get local ipaddr/name"); 2219 goto out; 2220 } 2221 2222 /* XXX sshbuf_put_stringf? */ 2223 xasprintf(&chost, "%s.", lname); 2224 debug2_f("chost %s", chost); 2225 2226 /* construct data */ 2227 if ((b = sshbuf_new()) == NULL) { 2228 error_f("sshbuf_new failed"); 2229 goto out; 2230 } 2231 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2232 error_fr(r, "sshkey_to_blob"); 2233 goto out; 2234 } 2235 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2236 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2237 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2238 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2239 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2240 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2241 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2242 (r = sshbuf_put_cstring(b, chost)) != 0 || 2243 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2244 error_fr(r, "buffer error"); 2245 goto out; 2246 } 2247 2248 #ifdef DEBUG_PK 2249 sshbuf_dump(b, stderr); 2250 #endif 2251 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2252 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2253 error("sign using hostkey %s %s failed", 2254 sshkey_ssh_name(private), fp); 2255 goto out; 2256 } 2257 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2258 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2259 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2260 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2261 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2262 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2263 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2264 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2265 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2266 (r = sshpkt_send(ssh)) != 0) { 2267 error_fr(r, "packet error"); 2268 goto out; 2269 } 2270 success = 1; 2271 2272 out: 2273 if (sig != NULL) 2274 freezero(sig, siglen); 2275 free(keyblob); 2276 free(lname); 2277 free(fp); 2278 free(chost); 2279 sshkey_free(private); 2280 sshbuf_free(b); 2281 2282 return success; 2283 } 2284 2285 #if KRB5 2286 static int 2287 ssh_krb5_helper(struct ssh *ssh, krb5_data *ap) 2288 { 2289 krb5_context xcontext = NULL; /* XXX share with ssh1 */ 2290 krb5_auth_context xauth_context = NULL; 2291 2292 krb5_context *context; 2293 krb5_auth_context *auth_context; 2294 krb5_error_code problem; 2295 const char *tkfile; 2296 struct stat buf; 2297 krb5_ccache ccache = NULL; 2298 const char *remotehost; 2299 int ret; 2300 const char *errtxt; 2301 2302 memset(ap, 0, sizeof(*ap)); 2303 2304 context = &xcontext; 2305 auth_context = &xauth_context; 2306 2307 problem = krb5_init_context(context); 2308 if (problem) { 2309 debug("Kerberos v5: krb5_init_context failed"); 2310 ret = 0; 2311 goto out; 2312 } 2313 2314 tkfile = krb5_cc_default_name(*context); 2315 if (strncmp(tkfile, "FILE:", 5) == 0) 2316 tkfile += 5; 2317 2318 if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { 2319 debug("Kerberos v5: could not get default ccache (permission denied)."); 2320 ret = 0; 2321 goto out; 2322 } 2323 2324 problem = krb5_cc_default(*context, &ccache); 2325 if (problem) { 2326 errtxt = krb5_get_error_message(*context, problem); 2327 if (errtxt != NULL) { 2328 debug("Kerberos v5: krb5_cc_default failed: %s", 2329 errtxt); 2330 krb5_free_error_message(*context, errtxt); 2331 } else 2332 debug("Kerberos v5: krb5_cc_default failed: %d", 2333 problem); 2334 ret = 0; 2335 goto out; 2336 } 2337 2338 remotehost = auth_get_canonical_hostname(ssh, 1); 2339 2340 problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, 2341 "host", remotehost, NULL, ccache, ap); 2342 if (problem) { 2343 errtxt = krb5_get_error_message(*context, problem); 2344 if (errtxt != NULL) { 2345 debug("Kerberos v5: krb5_mk_req failed: %s", errtxt); 2346 krb5_free_error_message(*context, errtxt); 2347 } else 2348 debug("Kerberos v5: krb5_mk_req failed: %d", problem); 2349 ret = 0; 2350 goto out; 2351 } 2352 ret = 1; 2353 2354 out: 2355 if (ccache != NULL) 2356 krb5_cc_close(*context, ccache); 2357 if (*auth_context) 2358 krb5_auth_con_free(*context, *auth_context); 2359 if (*context) 2360 krb5_free_context(*context); 2361 return (ret); 2362 } 2363 2364 static int 2365 userauth_kerberos(struct ssh *ssh) 2366 { 2367 krb5_data ap; 2368 int r; 2369 Authctxt *authctxt = ssh->authctxt; 2370 2371 if (ssh_krb5_helper(ssh, &ap) == 0) 2372 return (0); 2373 2374 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2375 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2376 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2377 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2378 (r = sshpkt_put_string(ssh, ap.data, ap.length)) != 0 || 2379 (r = sshpkt_send(ssh)) != 0 || 2380 (r = ssh_packet_write_wait(ssh)) < 0) 2381 fatal("%s: %s", __func__, ssh_err(r)); 2382 2383 krb5_data_free(&ap); 2384 return (1); 2385 } 2386 #endif 2387 2388 /* find auth method */ 2389 2390 /* 2391 * given auth method name, if configurable options permit this method fill 2392 * in auth_ident field and return true, otherwise return false. 2393 */ 2394 static int 2395 authmethod_is_enabled(Authmethod *method) 2396 { 2397 if (method == NULL) 2398 return 0; 2399 /* return false if options indicate this method is disabled */ 2400 if (method->enabled == NULL || *method->enabled == 0) 2401 return 0; 2402 /* return false if batch mode is enabled but method needs interactive mode */ 2403 if (method->batch_flag != NULL && *method->batch_flag != 0) 2404 return 0; 2405 return 1; 2406 } 2407 2408 static Authmethod * 2409 authmethod_lookup(const char *name) 2410 { 2411 Authmethod *method = NULL; 2412 if (name != NULL) 2413 for (method = authmethods; method->name != NULL; method++) 2414 if (strcmp(name, method->name) == 0) 2415 return method; 2416 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2417 return NULL; 2418 } 2419 2420 /* XXX internal state */ 2421 static Authmethod *current = NULL; 2422 static char *supported = NULL; 2423 static char *preferred = NULL; 2424 2425 /* 2426 * Given the authentication method list sent by the server, return the 2427 * next method we should try. If the server initially sends a nil list, 2428 * use a built-in default list. 2429 */ 2430 static Authmethod * 2431 authmethod_get(char *authlist) 2432 { 2433 char *name = NULL; 2434 u_int next; 2435 2436 /* Use a suitable default if we're passed a nil list. */ 2437 if (authlist == NULL || strlen(authlist) == 0) 2438 authlist = options.preferred_authentications; 2439 2440 if (supported == NULL || strcmp(authlist, supported) != 0) { 2441 debug3("start over, passed a different list %s", authlist); 2442 free(supported); 2443 supported = xstrdup(authlist); 2444 preferred = options.preferred_authentications; 2445 debug3("preferred %s", preferred); 2446 current = NULL; 2447 } else if (current != NULL && authmethod_is_enabled(current)) 2448 return current; 2449 2450 for (;;) { 2451 if ((name = match_list(preferred, supported, &next)) == NULL) { 2452 debug("No more authentication methods to try."); 2453 current = NULL; 2454 return NULL; 2455 } 2456 preferred += next; 2457 debug3("authmethod_lookup %s", name); 2458 debug3("remaining preferred: %s", preferred); 2459 if ((current = authmethod_lookup(name)) != NULL && 2460 authmethod_is_enabled(current)) { 2461 debug3("authmethod_is_enabled %s", name); 2462 debug("Next authentication method: %s", name); 2463 free(name); 2464 return current; 2465 } 2466 free(name); 2467 } 2468 } 2469 2470 static char * 2471 authmethods_get(void) 2472 { 2473 Authmethod *method = NULL; 2474 struct sshbuf *b; 2475 char *list; 2476 int r; 2477 2478 if ((b = sshbuf_new()) == NULL) 2479 fatal_f("sshbuf_new failed"); 2480 for (method = authmethods; method->name != NULL; method++) { 2481 if (authmethod_is_enabled(method)) { 2482 if ((r = sshbuf_putf(b, "%s%s", 2483 sshbuf_len(b) ? "," : "", method->name)) != 0) 2484 fatal_fr(r, "buffer error"); 2485 } 2486 } 2487 if ((list = sshbuf_dup_string(b)) == NULL) 2488 fatal_f("sshbuf_dup_string failed"); 2489 sshbuf_free(b); 2490 return list; 2491 } 2492