1 /* $OpenBSD: sshconnect2.c,v 1.359 2022/07/01 03:39:44 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 "myproposal.h" 55 #include "sshconnect.h" 56 #include "authfile.h" 57 #include "dh.h" 58 #include "authfd.h" 59 #include "log.h" 60 #include "misc.h" 61 #include "readconf.h" 62 #include "match.h" 63 #include "dispatch.h" 64 #include "canohost.h" 65 #include "msg.h" 66 #include "pathnames.h" 67 #include "uidswap.h" 68 #include "hostfile.h" 69 #include "ssherr.h" 70 #include "utf8.h" 71 #include "ssh-sk.h" 72 #include "sk-api.h" 73 74 #ifdef GSSAPI 75 #include "ssh-gss.h" 76 #endif 77 78 /* import */ 79 extern char *client_version_string; 80 extern char *server_version_string; 81 extern Options options; 82 83 /* 84 * SSH2 key exchange 85 */ 86 87 static char *xxx_host; 88 static struct sockaddr *xxx_hostaddr; 89 static const struct ssh_conn_info *xxx_conn_info; 90 91 static int 92 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 93 { 94 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, 95 xxx_conn_info) == -1) 96 fatal("Host key verification failed."); 97 return 0; 98 } 99 100 /* Returns the first item from a comma-separated algorithm list */ 101 static char * 102 first_alg(const char *algs) 103 { 104 char *ret, *cp; 105 106 ret = xstrdup(algs); 107 if ((cp = strchr(ret, ',')) != NULL) 108 *cp = '\0'; 109 return ret; 110 } 111 112 static char * 113 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port, 114 const struct ssh_conn_info *cinfo) 115 { 116 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 117 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 118 size_t maxlen; 119 struct hostkeys *hostkeys = NULL; 120 int ktype; 121 u_int i; 122 123 /* Find all hostkeys for this hostname */ 124 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 125 hostkeys = init_hostkeys(); 126 for (i = 0; i < options.num_user_hostfiles; i++) 127 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0); 128 for (i = 0; i < options.num_system_hostfiles; i++) { 129 load_hostkeys(hostkeys, hostname, 130 options.system_hostfiles[i], 0); 131 } 132 if (options.known_hosts_command != NULL) { 133 load_hostkeys_command(hostkeys, options.known_hosts_command, 134 "ORDER", cinfo, NULL, host); 135 } 136 /* 137 * If a plain public key exists that matches the type of the best 138 * preference HostkeyAlgorithms, then use the whole list as is. 139 * Note that we ignore whether the best preference algorithm is a 140 * certificate type, as sshconnect.c will downgrade certs to 141 * plain keys if necessary. 142 */ 143 best = first_alg(options.hostkeyalgorithms); 144 if (lookup_key_in_hostkeys_by_type(hostkeys, 145 sshkey_type_plain(sshkey_type_from_name(best)), 146 sshkey_ecdsa_nid_from_name(best), NULL)) { 147 debug3_f("have matching best-preference key type %s, " 148 "using HostkeyAlgorithms verbatim", best); 149 ret = xstrdup(options.hostkeyalgorithms); 150 goto out; 151 } 152 153 /* 154 * Otherwise, prefer the host key algorithms that match known keys 155 * while keeping the ordering of HostkeyAlgorithms as much as possible. 156 */ 157 oavail = avail = xstrdup(options.hostkeyalgorithms); 158 maxlen = strlen(avail) + 1; 159 first = xmalloc(maxlen); 160 last = xmalloc(maxlen); 161 *first = *last = '\0'; 162 163 #define ALG_APPEND(to, from) \ 164 do { \ 165 if (*to != '\0') \ 166 strlcat(to, ",", maxlen); \ 167 strlcat(to, from, maxlen); \ 168 } while (0) 169 170 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 171 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 172 fatal_f("unknown alg %s", alg); 173 /* 174 * If we have a @cert-authority marker in known_hosts then 175 * prefer all certificate algorithms. 176 */ 177 if (sshkey_type_is_cert(ktype) && 178 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 179 ALG_APPEND(first, alg); 180 continue; 181 } 182 /* If the key appears in known_hosts then prefer it */ 183 if (lookup_key_in_hostkeys_by_type(hostkeys, 184 sshkey_type_plain(ktype), 185 sshkey_ecdsa_nid_from_name(alg), NULL)) { 186 ALG_APPEND(first, alg); 187 continue; 188 } 189 /* Otherwise, put it last */ 190 ALG_APPEND(last, alg); 191 } 192 #undef ALG_APPEND 193 xasprintf(&ret, "%s%s%s", first, 194 (*first == '\0' || *last == '\0') ? "" : ",", last); 195 if (*first != '\0') 196 debug3_f("prefer hostkeyalgs: %s", first); 197 else 198 debug3_f("no algorithms matched; accept original"); 199 out: 200 free(best); 201 free(first); 202 free(last); 203 free(hostname); 204 free(oavail); 205 free_hostkeys(hostkeys); 206 207 return ret; 208 } 209 210 void 211 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, 212 const struct ssh_conn_info *cinfo) 213 { 214 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 215 char *s, *all_key; 216 char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; 217 int r, use_known_hosts_order = 0; 218 219 xxx_host = host; 220 xxx_hostaddr = hostaddr; 221 xxx_conn_info = cinfo; 222 223 /* 224 * If the user has not specified HostkeyAlgorithms, or has only 225 * appended or removed algorithms from that list then prefer algorithms 226 * that are in the list that are supported by known_hosts keys. 227 */ 228 if (options.hostkeyalgorithms == NULL || 229 options.hostkeyalgorithms[0] == '-' || 230 options.hostkeyalgorithms[0] == '+') 231 use_known_hosts_order = 1; 232 233 /* Expand or fill in HostkeyAlgorithms */ 234 all_key = sshkey_alg_list(0, 0, 1, ','); 235 if ((r = kex_assemble_names(&options.hostkeyalgorithms, 236 kex_default_pk_alg(), all_key)) != 0) 237 fatal_fr(r, "kex_assemble_namelist"); 238 free(all_key); 239 240 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 241 fatal_f("kex_names_cat"); 242 myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, s); 243 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 244 myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = 245 compat_cipher_proposal(ssh, options.ciphers); 246 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 247 myproposal[PROPOSAL_COMP_ALGS_STOC] = 248 (char *)compression_alg_list(options.compression); 249 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 250 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 251 if (use_known_hosts_order) { 252 /* Query known_hosts and prefer algorithms that appear there */ 253 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 254 compat_pkalg_proposal(ssh, 255 order_hostkeyalgs(host, hostaddr, port, cinfo)); 256 } else { 257 /* Use specified HostkeyAlgorithms exactly */ 258 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 259 compat_pkalg_proposal(ssh, options.hostkeyalgorithms); 260 } 261 262 if (options.rekey_limit || options.rekey_interval) 263 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 264 options.rekey_interval); 265 266 /* start key exchange */ 267 if ((r = kex_setup(ssh, myproposal)) != 0) 268 fatal_r(r, "kex_setup"); 269 #ifdef WITH_OPENSSL 270 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 271 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 272 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 273 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 274 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 275 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 276 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 277 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 278 #endif 279 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 280 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; 281 ssh->kex->verify_host_key=&verify_host_key_callback; 282 283 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 284 285 /* remove ext-info from the KEX proposals for rekeying */ 286 myproposal[PROPOSAL_KEX_ALGS] = 287 compat_kex_proposal(ssh, options.kex_algorithms); 288 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 289 fatal_r(r, "kex_prop2buf"); 290 291 #ifdef DEBUG_KEXDH 292 /* send 1st encrypted/maced/compressed message */ 293 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 294 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 295 (r = sshpkt_send(ssh)) != 0 || 296 (r = ssh_packet_write_wait(ssh)) != 0) 297 fatal_fr(r, "send packet"); 298 #endif 299 /* Free only parts of proposal that were dynamically allocated here. */ 300 free(prop_kex); 301 free(prop_enc); 302 free(prop_hostkey); 303 } 304 305 /* 306 * Authenticate user 307 */ 308 309 typedef struct cauthctxt Authctxt; 310 typedef struct cauthmethod Authmethod; 311 typedef struct identity Identity; 312 typedef struct idlist Idlist; 313 314 struct identity { 315 TAILQ_ENTRY(identity) next; 316 int agent_fd; /* >=0 if agent supports key */ 317 struct sshkey *key; /* public/private key */ 318 char *filename; /* comment for agent-only keys */ 319 int tried; 320 int isprivate; /* key points to the private key */ 321 int userprovided; 322 }; 323 TAILQ_HEAD(idlist, identity); 324 325 struct cauthctxt { 326 const char *server_user; 327 const char *local_user; 328 const char *host; 329 const char *service; 330 struct cauthmethod *method; 331 sig_atomic_t success; 332 char *authlist; 333 #ifdef GSSAPI 334 /* gssapi */ 335 gss_OID_set gss_supported_mechs; 336 u_int mech_tried; 337 #endif 338 /* pubkey */ 339 struct idlist keys; 340 int agent_fd; 341 /* hostbased */ 342 Sensitive *sensitive; 343 char *oktypes, *ktypes; 344 const char *active_ktype; 345 /* kbd-interactive */ 346 int info_req_seen; 347 int attempt_kbdint; 348 /* password */ 349 int attempt_passwd; 350 /* generic */ 351 void *methoddata; 352 }; 353 354 struct cauthmethod { 355 char *name; /* string to compare against server's list */ 356 int (*userauth)(struct ssh *ssh); 357 void (*cleanup)(struct ssh *ssh); 358 int *enabled; /* flag in option struct that enables method */ 359 int *batch_flag; /* flag in option struct that disables method */ 360 }; 361 362 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 363 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 364 static int input_userauth_success(int, u_int32_t, struct ssh *); 365 static int input_userauth_failure(int, u_int32_t, struct ssh *); 366 static int input_userauth_banner(int, u_int32_t, struct ssh *); 367 static int input_userauth_error(int, u_int32_t, struct ssh *); 368 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 369 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 370 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 371 372 static int userauth_none(struct ssh *); 373 static int userauth_pubkey(struct ssh *); 374 static int userauth_passwd(struct ssh *); 375 static int userauth_kbdint(struct ssh *); 376 static int userauth_hostbased(struct ssh *); 377 378 #ifdef GSSAPI 379 static int userauth_gssapi(struct ssh *); 380 static void userauth_gssapi_cleanup(struct ssh *); 381 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 382 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 383 static int input_gssapi_error(int, u_int32_t, struct ssh *); 384 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 385 #endif 386 387 void userauth(struct ssh *, char *); 388 389 static void pubkey_cleanup(struct ssh *); 390 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 391 static void pubkey_prepare(struct ssh *, Authctxt *); 392 static void pubkey_reset(Authctxt *); 393 static struct sshkey *load_identity_file(Identity *); 394 395 static Authmethod *authmethod_get(char *authlist); 396 static Authmethod *authmethod_lookup(const char *name); 397 static char *authmethods_get(void); 398 399 Authmethod authmethods[] = { 400 #ifdef GSSAPI 401 {"gssapi-with-mic", 402 userauth_gssapi, 403 userauth_gssapi_cleanup, 404 &options.gss_authentication, 405 NULL}, 406 #endif 407 {"hostbased", 408 userauth_hostbased, 409 NULL, 410 &options.hostbased_authentication, 411 NULL}, 412 {"publickey", 413 userauth_pubkey, 414 NULL, 415 &options.pubkey_authentication, 416 NULL}, 417 {"keyboard-interactive", 418 userauth_kbdint, 419 NULL, 420 &options.kbd_interactive_authentication, 421 &options.batch_mode}, 422 {"password", 423 userauth_passwd, 424 NULL, 425 &options.password_authentication, 426 &options.batch_mode}, 427 {"none", 428 userauth_none, 429 NULL, 430 NULL, 431 NULL}, 432 {NULL, NULL, NULL, NULL, NULL} 433 }; 434 435 void 436 ssh_userauth2(struct ssh *ssh, const char *local_user, 437 const char *server_user, char *host, Sensitive *sensitive) 438 { 439 Authctxt authctxt; 440 int r; 441 442 if (options.preferred_authentications == NULL) 443 options.preferred_authentications = authmethods_get(); 444 445 /* setup authentication context */ 446 memset(&authctxt, 0, sizeof(authctxt)); 447 authctxt.server_user = server_user; 448 authctxt.local_user = local_user; 449 authctxt.host = host; 450 authctxt.service = "ssh-connection"; /* service name */ 451 authctxt.success = 0; 452 authctxt.method = authmethod_lookup("none"); 453 authctxt.authlist = NULL; 454 authctxt.methoddata = NULL; 455 authctxt.sensitive = sensitive; 456 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 457 authctxt.info_req_seen = 0; 458 authctxt.attempt_kbdint = 0; 459 authctxt.attempt_passwd = 0; 460 #if GSSAPI 461 authctxt.gss_supported_mechs = NULL; 462 authctxt.mech_tried = 0; 463 #endif 464 authctxt.agent_fd = -1; 465 pubkey_prepare(ssh, &authctxt); 466 if (authctxt.method == NULL) { 467 fatal_f("internal error: cannot send userauth none request"); 468 } 469 470 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 471 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 472 (r = sshpkt_send(ssh)) != 0) 473 fatal_fr(r, "send packet"); 474 475 ssh->authctxt = &authctxt; 476 ssh_dispatch_init(ssh, &input_userauth_error); 477 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 478 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 479 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 480 pubkey_cleanup(ssh); 481 ssh->authctxt = NULL; 482 483 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 484 485 if (!authctxt.success) 486 fatal("Authentication failed."); 487 if (ssh_packet_connection_is_on_socket(ssh)) { 488 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, 489 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 490 authctxt.method->name); 491 } else { 492 verbose("Authenticated to %s (via proxy) using \"%s\".", host, 493 authctxt.method->name); 494 } 495 } 496 497 /* ARGSUSED */ 498 static int 499 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 500 { 501 int r; 502 503 if (ssh_packet_remaining(ssh) > 0) { 504 char *reply; 505 506 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 507 goto out; 508 debug2("service_accept: %s", reply); 509 free(reply); 510 } else { 511 debug2("buggy server: service_accept w/o service"); 512 } 513 if ((r = sshpkt_get_end(ssh)) != 0) 514 goto out; 515 debug("SSH2_MSG_SERVICE_ACCEPT received"); 516 517 /* initial userauth request */ 518 userauth_none(ssh); 519 520 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 521 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 522 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 523 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 524 r = 0; 525 out: 526 return r; 527 } 528 529 /* ARGSUSED */ 530 static int 531 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 532 { 533 return kex_input_ext_info(type, seqnr, ssh); 534 } 535 536 void 537 userauth(struct ssh *ssh, char *authlist) 538 { 539 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 540 541 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 542 authctxt->method->cleanup(ssh); 543 544 free(authctxt->methoddata); 545 authctxt->methoddata = NULL; 546 if (authlist == NULL) { 547 authlist = authctxt->authlist; 548 } else { 549 free(authctxt->authlist); 550 authctxt->authlist = authlist; 551 } 552 for (;;) { 553 Authmethod *method = authmethod_get(authlist); 554 if (method == NULL) 555 fatal("%s@%s: Permission denied (%s).", 556 authctxt->server_user, authctxt->host, authlist); 557 authctxt->method = method; 558 559 /* reset the per method handler */ 560 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 561 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 562 563 /* and try new method */ 564 if (method->userauth(ssh) != 0) { 565 debug2("we sent a %s packet, wait for reply", method->name); 566 break; 567 } else { 568 debug2("we did not send a packet, disable method"); 569 method->enabled = NULL; 570 } 571 } 572 } 573 574 /* ARGSUSED */ 575 static int 576 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 577 { 578 fatal_f("bad message during authentication: type %d", type); 579 return 0; 580 } 581 582 /* ARGSUSED */ 583 static int 584 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 585 { 586 char *msg = NULL; 587 size_t len; 588 int r; 589 590 debug3_f("entering"); 591 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 592 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 593 goto out; 594 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 595 fmprintf(stderr, "%s", msg); 596 r = 0; 597 out: 598 free(msg); 599 return r; 600 } 601 602 /* ARGSUSED */ 603 static int 604 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 605 { 606 Authctxt *authctxt = ssh->authctxt; 607 608 if (authctxt == NULL) 609 fatal_f("no authentication context"); 610 free(authctxt->authlist); 611 authctxt->authlist = NULL; 612 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 613 authctxt->method->cleanup(ssh); 614 free(authctxt->methoddata); 615 authctxt->methoddata = NULL; 616 authctxt->success = 1; /* break out */ 617 return 0; 618 } 619 620 #if 0 621 static int 622 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 623 { 624 Authctxt *authctxt = ssh->authctxt; 625 626 if (authctxt == NULL) 627 fatal_f("no authentication context"); 628 629 fatal("Unexpected authentication success during %s.", 630 authctxt->method->name); 631 return 0; 632 } 633 #endif 634 635 /* ARGSUSED */ 636 static int 637 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 638 { 639 Authctxt *authctxt = ssh->authctxt; 640 char *authlist = NULL; 641 u_char partial; 642 643 if (authctxt == NULL) 644 fatal("input_userauth_failure: no authentication context"); 645 646 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 647 sshpkt_get_u8(ssh, &partial) != 0 || 648 sshpkt_get_end(ssh) != 0) 649 goto out; 650 651 if (partial != 0) { 652 verbose("Authenticated using \"%s\" with partial success.", 653 authctxt->method->name); 654 /* reset state */ 655 pubkey_reset(authctxt); 656 } 657 debug("Authentications that can continue: %s", authlist); 658 659 userauth(ssh, authlist); 660 authlist = NULL; 661 out: 662 free(authlist); 663 return 0; 664 } 665 666 /* 667 * Format an identity for logging including filename, key type, fingerprint 668 * and location (agent, etc.). Caller must free. 669 */ 670 static char * 671 format_identity(Identity *id) 672 { 673 char *fp = NULL, *ret = NULL; 674 const char *note = ""; 675 676 if (id->key != NULL) { 677 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 678 SSH_FP_DEFAULT); 679 } 680 if (id->key) { 681 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 682 note = " token"; 683 else if (sshkey_is_sk(id->key)) 684 note = " authenticator"; 685 } 686 xasprintf(&ret, "%s %s%s%s%s%s%s", 687 id->filename, 688 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 689 fp ? fp : "", 690 id->userprovided ? " explicit" : "", note, 691 id->agent_fd != -1 ? " agent" : ""); 692 free(fp); 693 return ret; 694 } 695 696 /* ARGSUSED */ 697 static int 698 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 699 { 700 Authctxt *authctxt = ssh->authctxt; 701 struct sshkey *key = NULL; 702 Identity *id = NULL; 703 int pktype, found = 0, sent = 0; 704 size_t blen; 705 char *pkalg = NULL, *fp = NULL, *ident = NULL; 706 u_char *pkblob = NULL; 707 int r; 708 709 if (authctxt == NULL) 710 fatal("input_userauth_pk_ok: no authentication context"); 711 712 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 713 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 714 (r = sshpkt_get_end(ssh)) != 0) 715 goto done; 716 717 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 718 debug_f("server sent unknown pkalg %s", pkalg); 719 goto done; 720 } 721 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 722 debug_r(r, "no key from blob. pkalg %s", pkalg); 723 goto done; 724 } 725 if (key->type != pktype) { 726 error("input_userauth_pk_ok: type mismatch " 727 "for decoded key (received %d, expected %d)", 728 key->type, pktype); 729 goto done; 730 } 731 732 /* 733 * search keys in the reverse order, because last candidate has been 734 * moved to the end of the queue. this also avoids confusion by 735 * duplicate keys 736 */ 737 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 738 if (sshkey_equal(key, id->key)) { 739 found = 1; 740 break; 741 } 742 } 743 if (!found || id == NULL) { 744 fp = sshkey_fingerprint(key, options.fingerprint_hash, 745 SSH_FP_DEFAULT); 746 error_f("server replied with unknown key: %s %s", 747 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 748 goto done; 749 } 750 ident = format_identity(id); 751 debug("Server accepts key: %s", ident); 752 sent = sign_and_send_pubkey(ssh, id); 753 r = 0; 754 done: 755 sshkey_free(key); 756 free(ident); 757 free(fp); 758 free(pkalg); 759 free(pkblob); 760 761 /* try another method if we did not send a packet */ 762 if (r == 0 && sent == 0) 763 userauth(ssh, NULL); 764 return r; 765 } 766 767 #ifdef GSSAPI 768 static int 769 userauth_gssapi(struct ssh *ssh) 770 { 771 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 772 Gssctxt *gssctxt = NULL; 773 OM_uint32 min; 774 int r, ok = 0; 775 gss_OID mech = NULL; 776 777 /* Try one GSSAPI method at a time, rather than sending them all at 778 * once. */ 779 780 if (authctxt->gss_supported_mechs == NULL) 781 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 782 783 /* Check to see whether the mechanism is usable before we offer it */ 784 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 785 !ok) { 786 mech = &authctxt->gss_supported_mechs-> 787 elements[authctxt->mech_tried]; 788 /* My DER encoding requires length<128 */ 789 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 790 mech, authctxt->host)) { 791 ok = 1; /* Mechanism works */ 792 } else { 793 authctxt->mech_tried++; 794 } 795 } 796 797 if (!ok || mech == NULL) 798 return 0; 799 800 authctxt->methoddata=(void *)gssctxt; 801 802 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 803 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 804 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 805 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 806 (r = sshpkt_put_u32(ssh, 1)) != 0 || 807 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 808 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 809 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 810 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 811 (r = sshpkt_send(ssh)) != 0) 812 fatal_fr(r, "send packet"); 813 814 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 815 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 816 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 817 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 818 819 authctxt->mech_tried++; /* Move along to next candidate */ 820 821 return 1; 822 } 823 824 static void 825 userauth_gssapi_cleanup(struct ssh *ssh) 826 { 827 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 828 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 829 830 ssh_gssapi_delete_ctx(&gssctxt); 831 authctxt->methoddata = NULL; 832 833 free(authctxt->gss_supported_mechs); 834 authctxt->gss_supported_mechs = NULL; 835 } 836 837 static OM_uint32 838 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 839 { 840 Authctxt *authctxt = ssh->authctxt; 841 Gssctxt *gssctxt = authctxt->methoddata; 842 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 843 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 844 gss_buffer_desc gssbuf; 845 OM_uint32 status, ms, flags; 846 int r; 847 848 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 849 recv_tok, &send_tok, &flags); 850 851 if (send_tok.length > 0) { 852 u_char type = GSS_ERROR(status) ? 853 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 854 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 855 856 if ((r = sshpkt_start(ssh, type)) != 0 || 857 (r = sshpkt_put_string(ssh, send_tok.value, 858 send_tok.length)) != 0 || 859 (r = sshpkt_send(ssh)) != 0) 860 fatal_fr(r, "send %u packet", type); 861 862 gss_release_buffer(&ms, &send_tok); 863 } 864 865 if (status == GSS_S_COMPLETE) { 866 /* send either complete or MIC, depending on mechanism */ 867 if (!(flags & GSS_C_INTEG_FLAG)) { 868 if ((r = sshpkt_start(ssh, 869 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 870 (r = sshpkt_send(ssh)) != 0) 871 fatal_fr(r, "send completion"); 872 } else { 873 struct sshbuf *b; 874 875 if ((b = sshbuf_new()) == NULL) 876 fatal_f("sshbuf_new failed"); 877 ssh_gssapi_buildmic(b, authctxt->server_user, 878 authctxt->service, "gssapi-with-mic", 879 ssh->kex->session_id); 880 881 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 882 fatal_f("sshbuf_mutable_ptr failed"); 883 gssbuf.length = sshbuf_len(b); 884 885 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 886 887 if (!GSS_ERROR(status)) { 888 if ((r = sshpkt_start(ssh, 889 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 890 (r = sshpkt_put_string(ssh, mic.value, 891 mic.length)) != 0 || 892 (r = sshpkt_send(ssh)) != 0) 893 fatal_fr(r, "send MIC"); 894 } 895 896 sshbuf_free(b); 897 gss_release_buffer(&ms, &mic); 898 } 899 } 900 901 return status; 902 } 903 904 /* ARGSUSED */ 905 static int 906 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 907 { 908 Authctxt *authctxt = ssh->authctxt; 909 Gssctxt *gssctxt; 910 size_t oidlen; 911 u_char *oidv = NULL; 912 int r; 913 914 if (authctxt == NULL) 915 fatal("input_gssapi_response: no authentication context"); 916 gssctxt = authctxt->methoddata; 917 918 /* Setup our OID */ 919 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 920 goto done; 921 922 if (oidlen <= 2 || 923 oidv[0] != SSH_GSS_OIDTYPE || 924 oidv[1] != oidlen - 2) { 925 debug("Badly encoded mechanism OID received"); 926 userauth(ssh, NULL); 927 goto ok; 928 } 929 930 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 931 fatal("Server returned different OID than expected"); 932 933 if ((r = sshpkt_get_end(ssh)) != 0) 934 goto done; 935 936 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 937 /* Start again with next method on list */ 938 debug("Trying to start again"); 939 userauth(ssh, NULL); 940 goto ok; 941 } 942 ok: 943 r = 0; 944 done: 945 free(oidv); 946 return r; 947 } 948 949 /* ARGSUSED */ 950 static int 951 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 952 { 953 Authctxt *authctxt = ssh->authctxt; 954 gss_buffer_desc recv_tok; 955 u_char *p = NULL; 956 size_t len; 957 OM_uint32 status; 958 int r; 959 960 if (authctxt == NULL) 961 fatal("input_gssapi_response: no authentication context"); 962 963 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 964 (r = sshpkt_get_end(ssh)) != 0) 965 goto out; 966 967 recv_tok.value = p; 968 recv_tok.length = len; 969 status = process_gssapi_token(ssh, &recv_tok); 970 971 /* Start again with the next method in the list */ 972 if (GSS_ERROR(status)) { 973 userauth(ssh, NULL); 974 /* ok */ 975 } 976 r = 0; 977 out: 978 free(p); 979 return r; 980 } 981 982 /* ARGSUSED */ 983 static int 984 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 985 { 986 Authctxt *authctxt = ssh->authctxt; 987 Gssctxt *gssctxt; 988 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 989 gss_buffer_desc recv_tok; 990 OM_uint32 ms; 991 u_char *p = NULL; 992 size_t len; 993 int r; 994 995 if (authctxt == NULL) 996 fatal("input_gssapi_response: no authentication context"); 997 gssctxt = authctxt->methoddata; 998 999 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 1000 (r = sshpkt_get_end(ssh)) != 0) { 1001 free(p); 1002 return r; 1003 } 1004 1005 /* Stick it into GSSAPI and see what it says */ 1006 recv_tok.value = p; 1007 recv_tok.length = len; 1008 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 1009 &recv_tok, &send_tok, NULL); 1010 free(p); 1011 gss_release_buffer(&ms, &send_tok); 1012 1013 /* Server will be returning a failed packet after this one */ 1014 return 0; 1015 } 1016 1017 /* ARGSUSED */ 1018 static int 1019 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1020 { 1021 char *msg = NULL; 1022 char *lang = NULL; 1023 int r; 1024 1025 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1026 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1027 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1028 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1029 goto out; 1030 r = sshpkt_get_end(ssh); 1031 debug("Server GSSAPI Error:\n%s", msg); 1032 out: 1033 free(msg); 1034 free(lang); 1035 return r; 1036 } 1037 #endif /* GSSAPI */ 1038 1039 static int 1040 userauth_none(struct ssh *ssh) 1041 { 1042 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1043 int r; 1044 1045 /* initial userauth request */ 1046 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1047 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1048 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1049 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1050 (r = sshpkt_send(ssh)) != 0) 1051 fatal_fr(r, "send packet"); 1052 return 1; 1053 } 1054 1055 static int 1056 userauth_passwd(struct ssh *ssh) 1057 { 1058 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1059 char *password, *prompt = NULL; 1060 const char *host = options.host_key_alias ? options.host_key_alias : 1061 authctxt->host; 1062 int r; 1063 1064 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1065 return 0; 1066 1067 if (authctxt->attempt_passwd != 1) 1068 error("Permission denied, please try again."); 1069 1070 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1071 password = read_passphrase(prompt, 0); 1072 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1073 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1074 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1075 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1076 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1077 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1078 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1079 (r = sshpkt_send(ssh)) != 0) 1080 fatal_fr(r, "send packet"); 1081 1082 free(prompt); 1083 if (password != NULL) 1084 freezero(password, strlen(password)); 1085 1086 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1087 &input_userauth_passwd_changereq); 1088 1089 return 1; 1090 } 1091 1092 /* 1093 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1094 */ 1095 /* ARGSUSED */ 1096 static int 1097 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1098 { 1099 Authctxt *authctxt = ssh->authctxt; 1100 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1101 char prompt[256]; 1102 const char *host; 1103 int r; 1104 1105 debug2("input_userauth_passwd_changereq"); 1106 1107 if (authctxt == NULL) 1108 fatal("input_userauth_passwd_changereq: " 1109 "no authentication context"); 1110 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1111 1112 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1113 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1114 goto out; 1115 if (strlen(info) > 0) 1116 logit("%s", info); 1117 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1118 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1119 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1120 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1121 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1122 goto out; 1123 1124 snprintf(prompt, sizeof(prompt), 1125 "Enter %.30s@%.128s's old password: ", 1126 authctxt->server_user, host); 1127 password = read_passphrase(prompt, 0); 1128 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1129 goto out; 1130 1131 freezero(password, strlen(password)); 1132 password = NULL; 1133 while (password == NULL) { 1134 snprintf(prompt, sizeof(prompt), 1135 "Enter %.30s@%.128s's new password: ", 1136 authctxt->server_user, host); 1137 password = read_passphrase(prompt, RP_ALLOW_EOF); 1138 if (password == NULL) { 1139 /* bail out */ 1140 r = 0; 1141 goto out; 1142 } 1143 snprintf(prompt, sizeof(prompt), 1144 "Retype %.30s@%.128s's new password: ", 1145 authctxt->server_user, host); 1146 retype = read_passphrase(prompt, 0); 1147 if (strcmp(password, retype) != 0) { 1148 freezero(password, strlen(password)); 1149 logit("Mismatch; try again, EOF to quit."); 1150 password = NULL; 1151 } 1152 freezero(retype, strlen(retype)); 1153 } 1154 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1155 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1156 (r = sshpkt_send(ssh)) != 0) 1157 goto out; 1158 1159 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1160 &input_userauth_passwd_changereq); 1161 r = 0; 1162 out: 1163 if (password) 1164 freezero(password, strlen(password)); 1165 free(info); 1166 free(lang); 1167 return r; 1168 } 1169 1170 /* 1171 * Select an algorithm for publickey signatures. 1172 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1173 * 1174 * Call with ssh==NULL to ignore server-sig-algs extension list and 1175 * only attempt with the key's base signature type. 1176 */ 1177 static char * 1178 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1179 { 1180 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1181 const char *server_sig_algs; 1182 1183 /* 1184 * The signature algorithm will only differ from the key algorithm 1185 * for RSA keys/certs and when the server advertises support for 1186 * newer (SHA2) algorithms. 1187 */ 1188 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1189 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1190 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) { 1191 /* Filter base key signature alg against our configuration */ 1192 return match_list(sshkey_ssh_name(key), 1193 options.pubkey_accepted_algos, NULL); 1194 } 1195 1196 /* 1197 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but 1198 * fails to advertise it via SSH2_MSG_EXT_INFO. 1199 */ 1200 server_sig_algs = ssh->kex->server_sig_algs; 1201 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) 1202 server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; 1203 1204 /* 1205 * For RSA keys/certs, since these might have a different sig type: 1206 * find the first entry in PubkeyAcceptedAlgorithms of the right type 1207 * that also appears in the supported signature algorithms list from 1208 * the server. 1209 */ 1210 oallowed = allowed = xstrdup(options.pubkey_accepted_algos); 1211 while ((cp = strsep(&allowed, ",")) != NULL) { 1212 if (sshkey_type_from_name(cp) != key->type) 1213 continue; 1214 tmp = match_list(sshkey_sigalg_by_name(cp), 1215 server_sig_algs, NULL); 1216 if (tmp != NULL) 1217 alg = xstrdup(cp); 1218 free(tmp); 1219 if (alg != NULL) 1220 break; 1221 } 1222 free(oallowed); 1223 return alg; 1224 } 1225 1226 static int 1227 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1228 const u_char *data, size_t datalen, u_int compat, const char *alg) 1229 { 1230 struct sshkey *sign_key = NULL, *prv = NULL; 1231 int retried = 0, r = SSH_ERR_INTERNAL_ERROR; 1232 struct notifier_ctx *notifier = NULL; 1233 char *fp = NULL, *pin = NULL, *prompt = NULL; 1234 1235 *sigp = NULL; 1236 *lenp = 0; 1237 1238 /* The agent supports this key. */ 1239 if (id->key != NULL && id->agent_fd != -1) { 1240 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1241 data, datalen, alg, compat); 1242 } 1243 1244 /* 1245 * We have already loaded the private key or the private key is 1246 * stored in external hardware. 1247 */ 1248 if (id->key != NULL && 1249 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1250 sign_key = id->key; 1251 } else { 1252 /* Load the private key from the file. */ 1253 if ((prv = load_identity_file(id)) == NULL) 1254 return SSH_ERR_KEY_NOT_FOUND; 1255 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1256 error_f("private key %s contents do not match public", 1257 id->filename); 1258 r = SSH_ERR_KEY_NOT_FOUND; 1259 goto out; 1260 } 1261 sign_key = prv; 1262 if (sshkey_is_sk(sign_key)) { 1263 if ((sign_key->sk_flags & 1264 SSH_SK_USER_VERIFICATION_REQD)) { 1265 retry_pin: 1266 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1267 sshkey_type(sign_key), id->filename); 1268 pin = read_passphrase(prompt, 0); 1269 } 1270 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1271 /* XXX should batch mode just skip these? */ 1272 if ((fp = sshkey_fingerprint(sign_key, 1273 options.fingerprint_hash, 1274 SSH_FP_DEFAULT)) == NULL) 1275 fatal_f("fingerprint failed"); 1276 notifier = notify_start(options.batch_mode, 1277 "Confirm user presence for key %s %s", 1278 sshkey_type(sign_key), fp); 1279 free(fp); 1280 } 1281 } 1282 } 1283 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1284 alg, options.sk_provider, pin, compat)) != 0) { 1285 debug_fr(r, "sshkey_sign"); 1286 if (pin == NULL && !retried && sshkey_is_sk(sign_key) && 1287 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 1288 notify_complete(notifier, NULL); 1289 notifier = NULL; 1290 retried = 1; 1291 goto retry_pin; 1292 } 1293 goto out; 1294 } 1295 1296 /* 1297 * PKCS#11 tokens may not support all signature algorithms, 1298 * so check what we get back. 1299 */ 1300 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1301 debug_fr(r, "sshkey_check_sigtype"); 1302 goto out; 1303 } 1304 /* success */ 1305 r = 0; 1306 out: 1307 free(prompt); 1308 if (pin != NULL) 1309 freezero(pin, strlen(pin)); 1310 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); 1311 sshkey_free(prv); 1312 return r; 1313 } 1314 1315 static int 1316 id_filename_matches(Identity *id, Identity *private_id) 1317 { 1318 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL }; 1319 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1320 size_t i, slen; 1321 1322 if (strcmp(id->filename, private_id->filename) == 0) 1323 return 1; 1324 for (i = 0; suffixes[i]; i++) { 1325 slen = strlen(suffixes[i]); 1326 if (len > slen && plen == len - slen && 1327 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1328 memcmp(id->filename, private_id->filename, plen) == 0) 1329 return 1; 1330 } 1331 return 0; 1332 } 1333 1334 static int 1335 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1336 { 1337 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1338 struct sshbuf *b = NULL; 1339 Identity *private_id, *sign_id = NULL; 1340 u_char *signature = NULL; 1341 size_t slen = 0, skip = 0; 1342 int r, fallback_sigtype, sent = 0; 1343 char *alg = NULL, *fp = NULL; 1344 const char *loc = "", *method = "publickey"; 1345 int hostbound = 0; 1346 1347 /* prefer host-bound pubkey signatures if supported by server */ 1348 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && 1349 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { 1350 hostbound = 1; 1351 method = "publickey-hostbound-v00@openssh.com"; 1352 } 1353 1354 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1355 SSH_FP_DEFAULT)) == NULL) 1356 return 0; 1357 1358 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp); 1359 1360 /* 1361 * If the key is an certificate, try to find a matching private key 1362 * and use it to complete the signature. 1363 * If no such private key exists, fall back to trying the certificate 1364 * key itself in case it has a private half already loaded. 1365 * This will try to set sign_id to the private key that will perform 1366 * the signature. 1367 */ 1368 if (sshkey_is_cert(id->key)) { 1369 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1370 if (sshkey_equal_public(id->key, private_id->key) && 1371 id->key->type != private_id->key->type) { 1372 sign_id = private_id; 1373 break; 1374 } 1375 } 1376 /* 1377 * Exact key matches are preferred, but also allow 1378 * filename matches for non-PKCS#11/agent keys that 1379 * didn't load public keys. This supports the case 1380 * of keeping just a private key file and public 1381 * certificate on disk. 1382 */ 1383 if (sign_id == NULL && 1384 !id->isprivate && id->agent_fd == -1 && 1385 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1386 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1387 if (private_id->key == NULL && 1388 id_filename_matches(id, private_id)) { 1389 sign_id = private_id; 1390 break; 1391 } 1392 } 1393 } 1394 if (sign_id != NULL) { 1395 debug2_f("using private key \"%s\"%s for " 1396 "certificate", sign_id->filename, 1397 sign_id->agent_fd != -1 ? " from agent" : ""); 1398 } else { 1399 debug_f("no separate private key for certificate " 1400 "\"%s\"", id->filename); 1401 } 1402 } 1403 1404 /* 1405 * If the above didn't select another identity to do the signing 1406 * then default to the one we started with. 1407 */ 1408 if (sign_id == NULL) 1409 sign_id = id; 1410 1411 /* assemble and sign data */ 1412 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1413 free(alg); 1414 slen = 0; 1415 signature = NULL; 1416 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1417 id->key)) == NULL) { 1418 error_f("no mutual signature supported"); 1419 goto out; 1420 } 1421 debug3_f("signing using %s %s", alg, fp); 1422 1423 sshbuf_free(b); 1424 if ((b = sshbuf_new()) == NULL) 1425 fatal_f("sshbuf_new failed"); 1426 if (ssh->compat & SSH_OLD_SESSIONID) { 1427 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) 1428 fatal_fr(r, "sshbuf_putb"); 1429 } else { 1430 if ((r = sshbuf_put_stringb(b, 1431 ssh->kex->session_id)) != 0) 1432 fatal_fr(r, "sshbuf_put_stringb"); 1433 } 1434 skip = sshbuf_len(b); 1435 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1436 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1437 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1438 (r = sshbuf_put_cstring(b, method)) != 0 || 1439 (r = sshbuf_put_u8(b, 1)) != 0 || 1440 (r = sshbuf_put_cstring(b, alg)) != 0 || 1441 (r = sshkey_puts(id->key, b)) != 0) { 1442 fatal_fr(r, "assemble signed data"); 1443 } 1444 if (hostbound) { 1445 if (ssh->kex->initial_hostkey == NULL) { 1446 fatal_f("internal error: initial hostkey " 1447 "not recorded"); 1448 } 1449 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) 1450 fatal_fr(r, "assemble %s hostkey", method); 1451 } 1452 /* generate signature */ 1453 r = identity_sign(sign_id, &signature, &slen, 1454 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg); 1455 if (r == 0) 1456 break; 1457 else if (r == SSH_ERR_KEY_NOT_FOUND) 1458 goto out; /* soft failure */ 1459 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1460 !fallback_sigtype) { 1461 if (sign_id->agent_fd != -1) 1462 loc = "agent "; 1463 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1464 loc = "token "; 1465 logit("%skey %s %s returned incorrect signature type", 1466 loc, sshkey_type(id->key), fp); 1467 continue; 1468 } 1469 error_fr(r, "signing failed for %s \"%s\"%s", 1470 sshkey_type(sign_id->key), sign_id->filename, 1471 id->agent_fd != -1 ? " from agent" : ""); 1472 goto out; 1473 } 1474 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1475 fatal_f("no signature"); 1476 1477 /* append signature */ 1478 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1479 fatal_fr(r, "append signature"); 1480 1481 #ifdef DEBUG_PK 1482 sshbuf_dump(b, stderr); 1483 #endif 1484 /* skip session id and packet type */ 1485 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1486 fatal_fr(r, "consume"); 1487 1488 /* put remaining data from buffer into packet */ 1489 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1490 (r = sshpkt_putb(ssh, b)) != 0 || 1491 (r = sshpkt_send(ssh)) != 0) 1492 fatal_fr(r, "enqueue request"); 1493 1494 /* success */ 1495 sent = 1; 1496 1497 out: 1498 free(fp); 1499 free(alg); 1500 sshbuf_free(b); 1501 freezero(signature, slen); 1502 return sent; 1503 } 1504 1505 static int 1506 send_pubkey_test(struct ssh *ssh, Identity *id) 1507 { 1508 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1509 u_char *blob = NULL; 1510 char *alg = NULL; 1511 size_t bloblen; 1512 u_int have_sig = 0; 1513 int sent = 0, r; 1514 1515 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1516 debug_f("no mutual signature algorithm"); 1517 goto out; 1518 } 1519 1520 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1521 /* we cannot handle this key */ 1522 debug3_f("cannot handle key"); 1523 goto out; 1524 } 1525 /* register callback for USERAUTH_PK_OK message */ 1526 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1527 1528 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1529 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1530 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1531 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1532 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1533 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1534 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1535 (r = sshpkt_send(ssh)) != 0) 1536 fatal_fr(r, "send packet"); 1537 sent = 1; 1538 1539 out: 1540 free(alg); 1541 free(blob); 1542 return sent; 1543 } 1544 1545 static struct sshkey * 1546 load_identity_file(Identity *id) 1547 { 1548 struct sshkey *private = NULL; 1549 char prompt[300], *passphrase, *comment; 1550 int r, quit = 0, i; 1551 struct stat st; 1552 1553 if (stat(id->filename, &st) == -1) { 1554 do_log2(id->userprovided ? 1555 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1556 "no such identity: %s: %s", id->filename, strerror(errno)); 1557 return NULL; 1558 } 1559 snprintf(prompt, sizeof prompt, 1560 "Enter passphrase for key '%.100s': ", id->filename); 1561 for (i = 0; i <= options.number_of_password_prompts; i++) { 1562 if (i == 0) 1563 passphrase = ""; 1564 else { 1565 passphrase = read_passphrase(prompt, 0); 1566 if (*passphrase == '\0') { 1567 debug2("no passphrase given, try next key"); 1568 free(passphrase); 1569 break; 1570 } 1571 } 1572 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1573 passphrase, &private, &comment))) { 1574 case 0: 1575 break; 1576 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1577 if (options.batch_mode) { 1578 quit = 1; 1579 break; 1580 } 1581 if (i != 0) 1582 debug2("bad passphrase given, try again..."); 1583 break; 1584 case SSH_ERR_SYSTEM_ERROR: 1585 if (errno == ENOENT) { 1586 debug2_r(r, "Load key \"%s\"", id->filename); 1587 quit = 1; 1588 break; 1589 } 1590 /* FALLTHROUGH */ 1591 default: 1592 error_r(r, "Load key \"%s\"", id->filename); 1593 quit = 1; 1594 break; 1595 } 1596 if (private != NULL && sshkey_is_sk(private) && 1597 options.sk_provider == NULL) { 1598 debug("key \"%s\" is an authenticator-hosted key, " 1599 "but no provider specified", id->filename); 1600 sshkey_free(private); 1601 private = NULL; 1602 quit = 1; 1603 } 1604 if (!quit && private != NULL && id->agent_fd == -1 && 1605 !(id->key && id->isprivate)) 1606 maybe_add_key_to_agent(id->filename, private, comment, 1607 passphrase); 1608 if (i > 0) 1609 freezero(passphrase, strlen(passphrase)); 1610 free(comment); 1611 if (private != NULL || quit) 1612 break; 1613 } 1614 return private; 1615 } 1616 1617 static int 1618 key_type_allowed_by_config(struct sshkey *key) 1619 { 1620 if (match_pattern_list(sshkey_ssh_name(key), 1621 options.pubkey_accepted_algos, 0) == 1) 1622 return 1; 1623 1624 /* RSA keys/certs might be allowed by alternate signature types */ 1625 switch (key->type) { 1626 case KEY_RSA: 1627 if (match_pattern_list("rsa-sha2-512", 1628 options.pubkey_accepted_algos, 0) == 1) 1629 return 1; 1630 if (match_pattern_list("rsa-sha2-256", 1631 options.pubkey_accepted_algos, 0) == 1) 1632 return 1; 1633 break; 1634 case KEY_RSA_CERT: 1635 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1636 options.pubkey_accepted_algos, 0) == 1) 1637 return 1; 1638 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1639 options.pubkey_accepted_algos, 0) == 1) 1640 return 1; 1641 break; 1642 } 1643 return 0; 1644 } 1645 1646 /* obtain a list of keys from the agent */ 1647 static int 1648 get_agent_identities(struct ssh *ssh, int *agent_fdp, 1649 struct ssh_identitylist **idlistp) 1650 { 1651 int r, agent_fd; 1652 struct ssh_identitylist *idlist; 1653 1654 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1655 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1656 debug_fr(r, "ssh_get_authentication_socket"); 1657 return r; 1658 } 1659 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, 1660 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) 1661 debug_f("bound agent to hostkey"); 1662 else 1663 debug2_fr(r, "ssh_agent_bind_hostkey"); 1664 1665 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1666 debug_fr(r, "ssh_fetch_identitylist"); 1667 close(agent_fd); 1668 return r; 1669 } 1670 /* success */ 1671 *agent_fdp = agent_fd; 1672 *idlistp = idlist; 1673 debug_f("agent returned %zu keys", idlist->nkeys); 1674 return 0; 1675 } 1676 1677 /* 1678 * try keys in the following order: 1679 * 1. certificates listed in the config file 1680 * 2. other input certificates 1681 * 3. agent keys that are found in the config file 1682 * 4. other agent keys 1683 * 5. keys that are only listed in the config file 1684 */ 1685 static void 1686 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt) 1687 { 1688 struct identity *id, *id2, *tmp; 1689 struct idlist agent, files, *preferred; 1690 struct sshkey *key; 1691 int agent_fd = -1, i, r, found; 1692 size_t j; 1693 struct ssh_identitylist *idlist; 1694 char *ident; 1695 1696 TAILQ_INIT(&agent); /* keys from the agent */ 1697 TAILQ_INIT(&files); /* keys from the config file */ 1698 preferred = &authctxt->keys; 1699 TAILQ_INIT(preferred); /* preferred order of keys */ 1700 1701 /* list of keys stored in the filesystem and PKCS#11 */ 1702 for (i = 0; i < options.num_identity_files; i++) { 1703 key = options.identity_keys[i]; 1704 if (key && key->cert && 1705 key->cert->type != SSH2_CERT_TYPE_USER) { 1706 debug_f("ignoring certificate %s: not a user " 1707 "certificate", options.identity_files[i]); 1708 continue; 1709 } 1710 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1711 debug_f("ignoring authenticator-hosted key %s as no " 1712 "SecurityKeyProvider has been specified", 1713 options.identity_files[i]); 1714 continue; 1715 } 1716 options.identity_keys[i] = NULL; 1717 id = xcalloc(1, sizeof(*id)); 1718 id->agent_fd = -1; 1719 id->key = key; 1720 id->filename = xstrdup(options.identity_files[i]); 1721 id->userprovided = options.identity_file_userprovided[i]; 1722 TAILQ_INSERT_TAIL(&files, id, next); 1723 } 1724 /* list of certificates specified by user */ 1725 for (i = 0; i < options.num_certificate_files; i++) { 1726 key = options.certificates[i]; 1727 if (!sshkey_is_cert(key) || key->cert == NULL || 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 " 1735 "certificate %s as no " 1736 "SecurityKeyProvider has been specified", 1737 options.identity_files[i]); 1738 continue; 1739 } 1740 id = xcalloc(1, sizeof(*id)); 1741 id->agent_fd = -1; 1742 id->key = key; 1743 id->filename = xstrdup(options.certificate_files[i]); 1744 id->userprovided = options.certificate_file_userprovided[i]; 1745 TAILQ_INSERT_TAIL(preferred, id, next); 1746 } 1747 /* list of keys supported by the agent */ 1748 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { 1749 for (j = 0; j < idlist->nkeys; j++) { 1750 found = 0; 1751 TAILQ_FOREACH(id, &files, next) { 1752 /* 1753 * agent keys from the config file are 1754 * preferred 1755 */ 1756 if (sshkey_equal(idlist->keys[j], id->key)) { 1757 TAILQ_REMOVE(&files, id, next); 1758 TAILQ_INSERT_TAIL(preferred, id, next); 1759 id->agent_fd = agent_fd; 1760 found = 1; 1761 break; 1762 } 1763 } 1764 if (!found && !options.identities_only) { 1765 id = xcalloc(1, sizeof(*id)); 1766 /* XXX "steals" key/comment from idlist */ 1767 id->key = idlist->keys[j]; 1768 id->filename = idlist->comments[j]; 1769 idlist->keys[j] = NULL; 1770 idlist->comments[j] = NULL; 1771 id->agent_fd = agent_fd; 1772 TAILQ_INSERT_TAIL(&agent, id, next); 1773 } 1774 } 1775 ssh_free_identitylist(idlist); 1776 /* append remaining agent keys */ 1777 TAILQ_CONCAT(preferred, &agent, next); 1778 authctxt->agent_fd = agent_fd; 1779 } 1780 /* Prefer PKCS11 keys that are explicitly listed */ 1781 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1782 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1783 continue; 1784 found = 0; 1785 TAILQ_FOREACH(id2, &files, next) { 1786 if (id2->key == NULL || 1787 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1788 continue; 1789 if (sshkey_equal(id->key, id2->key)) { 1790 TAILQ_REMOVE(&files, id, next); 1791 TAILQ_INSERT_TAIL(preferred, id, next); 1792 found = 1; 1793 break; 1794 } 1795 } 1796 /* If IdentitiesOnly set and key not found then don't use it */ 1797 if (!found && options.identities_only) { 1798 TAILQ_REMOVE(&files, id, next); 1799 freezero(id, sizeof(*id)); 1800 } 1801 } 1802 /* append remaining keys from the config file */ 1803 TAILQ_CONCAT(preferred, &files, next); 1804 /* finally, filter by PubkeyAcceptedAlgorithms */ 1805 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1806 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1807 debug("Skipping %s key %s - " 1808 "corresponding algo not in PubkeyAcceptedAlgorithms", 1809 sshkey_ssh_name(id->key), id->filename); 1810 TAILQ_REMOVE(preferred, id, next); 1811 sshkey_free(id->key); 1812 free(id->filename); 1813 memset(id, 0, sizeof(*id)); 1814 continue; 1815 } 1816 } 1817 /* List the keys we plan on using */ 1818 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1819 ident = format_identity(id); 1820 debug("Will attempt key: %s", ident); 1821 free(ident); 1822 } 1823 debug2_f("done"); 1824 } 1825 1826 static void 1827 pubkey_cleanup(struct ssh *ssh) 1828 { 1829 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1830 Identity *id; 1831 1832 if (authctxt->agent_fd != -1) { 1833 ssh_close_authentication_socket(authctxt->agent_fd); 1834 authctxt->agent_fd = -1; 1835 } 1836 for (id = TAILQ_FIRST(&authctxt->keys); id; 1837 id = TAILQ_FIRST(&authctxt->keys)) { 1838 TAILQ_REMOVE(&authctxt->keys, id, next); 1839 sshkey_free(id->key); 1840 free(id->filename); 1841 free(id); 1842 } 1843 } 1844 1845 static void 1846 pubkey_reset(Authctxt *authctxt) 1847 { 1848 Identity *id; 1849 1850 TAILQ_FOREACH(id, &authctxt->keys, next) 1851 id->tried = 0; 1852 } 1853 1854 static int 1855 try_identity(struct ssh *ssh, Identity *id) 1856 { 1857 if (!id->key) 1858 return (0); 1859 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1860 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 1861 debug("Skipped %s key %s for RSA/MD5 server", 1862 sshkey_type(id->key), id->filename); 1863 return (0); 1864 } 1865 return 1; 1866 } 1867 1868 static int 1869 userauth_pubkey(struct ssh *ssh) 1870 { 1871 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1872 Identity *id; 1873 int sent = 0; 1874 char *ident; 1875 1876 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1877 if (id->tried++) 1878 return (0); 1879 /* move key to the end of the queue */ 1880 TAILQ_REMOVE(&authctxt->keys, id, next); 1881 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1882 /* 1883 * send a test message if we have the public key. for 1884 * encrypted keys we cannot do this and have to load the 1885 * private key instead 1886 */ 1887 if (id->key != NULL) { 1888 if (try_identity(ssh, id)) { 1889 ident = format_identity(id); 1890 debug("Offering public key: %s", ident); 1891 free(ident); 1892 sent = send_pubkey_test(ssh, id); 1893 } 1894 } else { 1895 debug("Trying private key: %s", id->filename); 1896 id->key = load_identity_file(id); 1897 if (id->key != NULL) { 1898 if (try_identity(ssh, id)) { 1899 id->isprivate = 1; 1900 sent = sign_and_send_pubkey(ssh, id); 1901 } 1902 sshkey_free(id->key); 1903 id->key = NULL; 1904 id->isprivate = 0; 1905 } 1906 } 1907 if (sent) 1908 return (sent); 1909 } 1910 return (0); 1911 } 1912 1913 /* 1914 * Send userauth request message specifying keyboard-interactive method. 1915 */ 1916 static int 1917 userauth_kbdint(struct ssh *ssh) 1918 { 1919 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1920 int r; 1921 1922 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1923 return 0; 1924 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1925 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1926 debug3("userauth_kbdint: disable: no info_req_seen"); 1927 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1928 return 0; 1929 } 1930 1931 debug2("userauth_kbdint"); 1932 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1933 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1934 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1935 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1936 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1937 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1938 options.kbd_interactive_devices : "")) != 0 || 1939 (r = sshpkt_send(ssh)) != 0) 1940 fatal_fr(r, "send packet"); 1941 1942 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1943 return 1; 1944 } 1945 1946 /* 1947 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1948 */ 1949 static int 1950 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1951 { 1952 Authctxt *authctxt = ssh->authctxt; 1953 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1954 char *display_prompt = NULL, *response = NULL; 1955 u_char echo = 0; 1956 u_int num_prompts, i; 1957 int r; 1958 1959 debug2_f("entering"); 1960 1961 if (authctxt == NULL) 1962 fatal_f("no authentication context"); 1963 1964 authctxt->info_req_seen = 1; 1965 1966 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1967 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1968 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1969 goto out; 1970 if (strlen(name) > 0) 1971 logit("%s", name); 1972 if (strlen(inst) > 0) 1973 logit("%s", inst); 1974 1975 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1976 goto out; 1977 /* 1978 * Begin to build info response packet based on prompts requested. 1979 * We commit to providing the correct number of responses, so if 1980 * further on we run into a problem that prevents this, we have to 1981 * be sure and clean this up and send a correct error response. 1982 */ 1983 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1984 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1985 goto out; 1986 1987 debug2_f("num_prompts %d", num_prompts); 1988 for (i = 0; i < num_prompts; i++) { 1989 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1990 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1991 goto out; 1992 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", 1993 authctxt->server_user, options.host_key_alias ? 1994 options.host_key_alias : authctxt->host, prompt) == -1) 1995 fatal_f("asmprintf failed"); 1996 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); 1997 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1998 goto out; 1999 freezero(response, strlen(response)); 2000 free(prompt); 2001 free(display_prompt); 2002 display_prompt = response = prompt = NULL; 2003 } 2004 /* done with parsing incoming message. */ 2005 if ((r = sshpkt_get_end(ssh)) != 0 || 2006 (r = sshpkt_add_padding(ssh, 64)) != 0) 2007 goto out; 2008 r = sshpkt_send(ssh); 2009 out: 2010 if (response) 2011 freezero(response, strlen(response)); 2012 free(prompt); 2013 free(display_prompt); 2014 free(name); 2015 free(inst); 2016 free(lang); 2017 return r; 2018 } 2019 2020 static int 2021 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 2022 const u_char *data, size_t datalen) 2023 { 2024 struct sshbuf *b; 2025 struct stat st; 2026 pid_t pid; 2027 int r, to[2], from[2], status; 2028 int sock = ssh_packet_get_connection_in(ssh); 2029 u_char rversion = 0, version = 2; 2030 void (*osigchld)(int); 2031 2032 *sigp = NULL; 2033 *lenp = 0; 2034 2035 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 2036 error_f("not installed: %s", strerror(errno)); 2037 return -1; 2038 } 2039 if (fflush(stdout) != 0) { 2040 error_f("fflush: %s", strerror(errno)); 2041 return -1; 2042 } 2043 if (pipe(to) == -1) { 2044 error_f("pipe: %s", strerror(errno)); 2045 return -1; 2046 } 2047 if (pipe(from) == -1) { 2048 error_f("pipe: %s", strerror(errno)); 2049 return -1; 2050 } 2051 if ((pid = fork()) == -1) { 2052 error_f("fork: %s", strerror(errno)); 2053 return -1; 2054 } 2055 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 2056 if (pid == 0) { 2057 close(from[0]); 2058 if (dup2(from[1], STDOUT_FILENO) == -1) 2059 fatal_f("dup2: %s", strerror(errno)); 2060 close(to[1]); 2061 if (dup2(to[0], STDIN_FILENO) == -1) 2062 fatal_f("dup2: %s", strerror(errno)); 2063 close(from[1]); 2064 close(to[0]); 2065 2066 if (dup2(sock, STDERR_FILENO + 1) == -1) 2067 fatal_f("dup2: %s", strerror(errno)); 2068 sock = STDERR_FILENO + 1; 2069 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2070 closefrom(sock + 1); 2071 2072 debug3_f("[child] pid=%ld, exec %s", 2073 (long)getpid(), _PATH_SSH_KEY_SIGN); 2074 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2075 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, 2076 strerror(errno)); 2077 } 2078 close(from[1]); 2079 close(to[0]); 2080 sock = STDERR_FILENO + 1; 2081 2082 if ((b = sshbuf_new()) == NULL) 2083 fatal_f("sshbuf_new failed"); 2084 /* send # of sock, data to be signed */ 2085 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2086 (r = sshbuf_put_string(b, data, datalen)) != 0) 2087 fatal_fr(r, "buffer error"); 2088 if (ssh_msg_send(to[1], version, b) == -1) 2089 fatal_f("couldn't send request"); 2090 sshbuf_reset(b); 2091 r = ssh_msg_recv(from[0], b); 2092 close(from[0]); 2093 close(to[1]); 2094 if (r < 0) { 2095 error_f("no reply"); 2096 goto fail; 2097 } 2098 2099 errno = 0; 2100 while (waitpid(pid, &status, 0) == -1) { 2101 if (errno != EINTR) { 2102 error_f("waitpid %ld: %s", (long)pid, strerror(errno)); 2103 goto fail; 2104 } 2105 } 2106 if (!WIFEXITED(status)) { 2107 error_f("exited abnormally"); 2108 goto fail; 2109 } 2110 if (WEXITSTATUS(status) != 0) { 2111 error_f("exited with status %d", WEXITSTATUS(status)); 2112 goto fail; 2113 } 2114 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2115 error_fr(r, "buffer error"); 2116 goto fail; 2117 } 2118 if (rversion != version) { 2119 error_f("bad version"); 2120 goto fail; 2121 } 2122 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2123 error_fr(r, "buffer error"); 2124 fail: 2125 ssh_signal(SIGCHLD, osigchld); 2126 sshbuf_free(b); 2127 return -1; 2128 } 2129 ssh_signal(SIGCHLD, osigchld); 2130 sshbuf_free(b); 2131 2132 return 0; 2133 } 2134 2135 static int 2136 userauth_hostbased(struct ssh *ssh) 2137 { 2138 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2139 struct sshkey *private = NULL; 2140 struct sshbuf *b = NULL; 2141 u_char *sig = NULL, *keyblob = NULL; 2142 char *fp = NULL, *chost = NULL, *lname = NULL; 2143 size_t siglen = 0, keylen = 0; 2144 int i, r, success = 0; 2145 2146 if (authctxt->ktypes == NULL) { 2147 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos); 2148 authctxt->ktypes = authctxt->oktypes; 2149 } 2150 2151 /* 2152 * Work through each listed type pattern in HostbasedAcceptedAlgorithms, 2153 * trying each hostkey that matches the type in turn. 2154 */ 2155 for (;;) { 2156 if (authctxt->active_ktype == NULL) 2157 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2158 if (authctxt->active_ktype == NULL || 2159 *authctxt->active_ktype == '\0') 2160 break; 2161 debug3_f("trying key type %s", authctxt->active_ktype); 2162 2163 /* check for a useful key */ 2164 private = NULL; 2165 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2166 if (authctxt->sensitive->keys[i] == NULL || 2167 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2168 continue; 2169 if (!sshkey_match_keyname_to_sigalgs( 2170 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2171 authctxt->active_ktype)) 2172 continue; 2173 /* we take and free the key */ 2174 private = authctxt->sensitive->keys[i]; 2175 authctxt->sensitive->keys[i] = NULL; 2176 break; 2177 } 2178 /* Found one */ 2179 if (private != NULL) 2180 break; 2181 /* No more keys of this type; advance */ 2182 authctxt->active_ktype = NULL; 2183 } 2184 if (private == NULL) { 2185 free(authctxt->oktypes); 2186 authctxt->oktypes = authctxt->ktypes = NULL; 2187 authctxt->active_ktype = NULL; 2188 debug("No more client hostkeys for hostbased authentication."); 2189 goto out; 2190 } 2191 2192 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2193 SSH_FP_DEFAULT)) == NULL) { 2194 error_f("sshkey_fingerprint failed"); 2195 goto out; 2196 } 2197 debug_f("trying hostkey %s %s using sigalg %s", 2198 sshkey_ssh_name(private), fp, authctxt->active_ktype); 2199 2200 /* figure out a name for the client host */ 2201 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2202 if (lname == NULL) { 2203 error_f("cannot get local ipaddr/name"); 2204 goto out; 2205 } 2206 2207 /* XXX sshbuf_put_stringf? */ 2208 xasprintf(&chost, "%s.", lname); 2209 debug2_f("chost %s", chost); 2210 2211 /* construct data */ 2212 if ((b = sshbuf_new()) == NULL) { 2213 error_f("sshbuf_new failed"); 2214 goto out; 2215 } 2216 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2217 error_fr(r, "sshkey_to_blob"); 2218 goto out; 2219 } 2220 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 || 2221 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2222 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2223 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2224 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2225 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 || 2226 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2227 (r = sshbuf_put_cstring(b, chost)) != 0 || 2228 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2229 error_fr(r, "buffer error"); 2230 goto out; 2231 } 2232 2233 #ifdef DEBUG_PK 2234 sshbuf_dump(b, stderr); 2235 #endif 2236 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2237 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2238 error("sign using hostkey %s %s failed", 2239 sshkey_ssh_name(private), fp); 2240 goto out; 2241 } 2242 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2243 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2244 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2245 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2246 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 || 2247 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2248 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2249 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2250 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2251 (r = sshpkt_send(ssh)) != 0) { 2252 error_fr(r, "packet error"); 2253 goto out; 2254 } 2255 success = 1; 2256 2257 out: 2258 if (sig != NULL) 2259 freezero(sig, siglen); 2260 free(keyblob); 2261 free(lname); 2262 free(fp); 2263 free(chost); 2264 sshkey_free(private); 2265 sshbuf_free(b); 2266 2267 return success; 2268 } 2269 2270 /* find auth method */ 2271 2272 /* 2273 * given auth method name, if configurable options permit this method fill 2274 * in auth_ident field and return true, otherwise return false. 2275 */ 2276 static int 2277 authmethod_is_enabled(Authmethod *method) 2278 { 2279 if (method == NULL) 2280 return 0; 2281 /* return false if options indicate this method is disabled */ 2282 if (method->enabled == NULL || *method->enabled == 0) 2283 return 0; 2284 /* return false if batch mode is enabled but method needs interactive mode */ 2285 if (method->batch_flag != NULL && *method->batch_flag != 0) 2286 return 0; 2287 return 1; 2288 } 2289 2290 static Authmethod * 2291 authmethod_lookup(const char *name) 2292 { 2293 Authmethod *method = NULL; 2294 if (name != NULL) 2295 for (method = authmethods; method->name != NULL; method++) 2296 if (strcmp(name, method->name) == 0) 2297 return method; 2298 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2299 return NULL; 2300 } 2301 2302 /* XXX internal state */ 2303 static Authmethod *current = NULL; 2304 static char *supported = NULL; 2305 static char *preferred = NULL; 2306 2307 /* 2308 * Given the authentication method list sent by the server, return the 2309 * next method we should try. If the server initially sends a nil list, 2310 * use a built-in default list. 2311 */ 2312 static Authmethod * 2313 authmethod_get(char *authlist) 2314 { 2315 char *name = NULL; 2316 u_int next; 2317 2318 /* Use a suitable default if we're passed a nil list. */ 2319 if (authlist == NULL || strlen(authlist) == 0) 2320 authlist = options.preferred_authentications; 2321 2322 if (supported == NULL || strcmp(authlist, supported) != 0) { 2323 debug3("start over, passed a different list %s", authlist); 2324 free(supported); 2325 supported = xstrdup(authlist); 2326 preferred = options.preferred_authentications; 2327 debug3("preferred %s", preferred); 2328 current = NULL; 2329 } else if (current != NULL && authmethod_is_enabled(current)) 2330 return current; 2331 2332 for (;;) { 2333 if ((name = match_list(preferred, supported, &next)) == NULL) { 2334 debug("No more authentication methods to try."); 2335 current = NULL; 2336 return NULL; 2337 } 2338 preferred += next; 2339 debug3("authmethod_lookup %s", name); 2340 debug3("remaining preferred: %s", preferred); 2341 if ((current = authmethod_lookup(name)) != NULL && 2342 authmethod_is_enabled(current)) { 2343 debug3("authmethod_is_enabled %s", name); 2344 debug("Next authentication method: %s", name); 2345 free(name); 2346 return current; 2347 } 2348 free(name); 2349 } 2350 } 2351 2352 static char * 2353 authmethods_get(void) 2354 { 2355 Authmethod *method = NULL; 2356 struct sshbuf *b; 2357 char *list; 2358 int r; 2359 2360 if ((b = sshbuf_new()) == NULL) 2361 fatal_f("sshbuf_new failed"); 2362 for (method = authmethods; method->name != NULL; method++) { 2363 if (authmethod_is_enabled(method)) { 2364 if ((r = sshbuf_putf(b, "%s%s", 2365 sshbuf_len(b) ? "," : "", method->name)) != 0) 2366 fatal_fr(r, "buffer error"); 2367 } 2368 } 2369 if ((list = sshbuf_dup_string(b)) == NULL) 2370 fatal_f("sshbuf_dup_string failed"); 2371 sshbuf_free(b); 2372 return list; 2373 } 2374