1 /* $OpenBSD: sshconnect2.c,v 1.330 2020/10/16 02:37:12 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <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 <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <stdarg.h> 39 #include <signal.h> 40 #include <pwd.h> 41 #include <unistd.h> 42 #include <vis.h> 43 44 #include "xmalloc.h" 45 #include "ssh.h" 46 #include "ssh2.h" 47 #include "sshbuf.h" 48 #include "packet.h" 49 #include "compat.h" 50 #include "cipher.h" 51 #include "sshkey.h" 52 #include "kex.h" 53 #include "myproposal.h" 54 #include "sshconnect.h" 55 #include "authfile.h" 56 #include "dh.h" 57 #include "authfd.h" 58 #include "log.h" 59 #include "misc.h" 60 #include "readconf.h" 61 #include "match.h" 62 #include "dispatch.h" 63 #include "canohost.h" 64 #include "msg.h" 65 #include "pathnames.h" 66 #include "uidswap.h" 67 #include "hostfile.h" 68 #include "ssherr.h" 69 #include "utf8.h" 70 #include "ssh-sk.h" 71 #include "sk-api.h" 72 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 77 /* import */ 78 extern char *client_version_string; 79 extern char *server_version_string; 80 extern Options options; 81 82 /* 83 * SSH2 key exchange 84 */ 85 86 u_char *session_id2 = NULL; 87 u_int session_id2_len = 0; 88 89 char *xxx_host; 90 struct sockaddr *xxx_hostaddr; 91 92 static int 93 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 94 { 95 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -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 { 115 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL; 116 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL; 117 size_t maxlen; 118 struct hostkeys *hostkeys = NULL; 119 int ktype; 120 u_int i; 121 122 /* Find all hostkeys for this hostname */ 123 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 124 hostkeys = init_hostkeys(); 125 for (i = 0; i < options.num_user_hostfiles; i++) 126 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 127 for (i = 0; i < options.num_system_hostfiles; i++) 128 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 129 130 /* 131 * If a plain public key exists that matches the type of the best 132 * preference HostkeyAlgorithms, then use the whole list as is. 133 * Note that we ignore whether the best preference algorithm is a 134 * certificate type, as sshconnect.c will downgrade certs to 135 * plain keys if necessary. 136 */ 137 best = first_alg(options.hostkeyalgorithms); 138 if (lookup_key_in_hostkeys_by_type(hostkeys, 139 sshkey_type_plain(sshkey_type_from_name(best)), 140 sshkey_ecdsa_nid_from_name(best), NULL)) { 141 debug3("%s: have matching best-preference key type %s, " 142 "using HostkeyAlgorithms verbatim", __func__, best); 143 ret = xstrdup(options.hostkeyalgorithms); 144 goto out; 145 } 146 147 /* 148 * Otherwise, prefer the host key algorithms that match known keys 149 * while keeping the ordering of HostkeyAlgorithms as much as possible. 150 */ 151 oavail = avail = xstrdup(options.hostkeyalgorithms); 152 maxlen = strlen(avail) + 1; 153 first = xmalloc(maxlen); 154 last = xmalloc(maxlen); 155 *first = *last = '\0'; 156 157 #define ALG_APPEND(to, from) \ 158 do { \ 159 if (*to != '\0') \ 160 strlcat(to, ",", maxlen); \ 161 strlcat(to, from, maxlen); \ 162 } while (0) 163 164 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 165 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 166 fatal("%s: unknown alg %s", __func__, alg); 167 /* 168 * If we have a @cert-authority marker in known_hosts then 169 * prefer all certificate algorithms. 170 */ 171 if (sshkey_type_is_cert(ktype) && 172 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 173 ALG_APPEND(first, alg); 174 continue; 175 } 176 /* If the key appears in known_hosts then prefer it */ 177 if (lookup_key_in_hostkeys_by_type(hostkeys, 178 sshkey_type_plain(ktype), 179 sshkey_ecdsa_nid_from_name(alg), NULL)) { 180 ALG_APPEND(first, alg); 181 continue; 182 } 183 /* Otherwise, put it last */ 184 ALG_APPEND(last, alg); 185 } 186 #undef ALG_APPEND 187 xasprintf(&ret, "%s%s%s", first, 188 (*first == '\0' || *last == '\0') ? "" : ",", last); 189 if (*first != '\0') 190 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 191 192 out: 193 free(best); 194 free(first); 195 free(last); 196 free(hostname); 197 free(oavail); 198 free_hostkeys(hostkeys); 199 200 return ret; 201 } 202 203 void 204 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 205 { 206 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 207 char *s, *all_key; 208 int r, use_known_hosts_order = 0; 209 210 xxx_host = host; 211 xxx_hostaddr = hostaddr; 212 213 /* 214 * If the user has not specified HostkeyAlgorithms, or has only 215 * appended or removed algorithms from that list then prefer algorithms 216 * that are in the list that are supported by known_hosts keys. 217 */ 218 if (options.hostkeyalgorithms == NULL || 219 options.hostkeyalgorithms[0] == '-' || 220 options.hostkeyalgorithms[0] == '+') 221 use_known_hosts_order = 1; 222 223 /* Expand or fill in HostkeyAlgorithms */ 224 all_key = sshkey_alg_list(0, 0, 1, ','); 225 if (kex_assemble_names(&options.hostkeyalgorithms, 226 kex_default_pk_alg(), all_key) != 0) 227 fatal("%s: kex_assemble_namelist", __func__); 228 free(all_key); 229 230 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 231 fatal("%s: kex_names_cat", __func__); 232 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 233 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 234 compat_cipher_proposal(options.ciphers); 235 myproposal[PROPOSAL_ENC_ALGS_STOC] = 236 compat_cipher_proposal(options.ciphers); 237 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 238 myproposal[PROPOSAL_COMP_ALGS_STOC] = 239 (char *)compression_alg_list(options.compression); 240 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 241 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 242 if (use_known_hosts_order) { 243 /* Query known_hosts and prefer algorithms that appear there */ 244 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 245 compat_pkalg_proposal( 246 order_hostkeyalgs(host, hostaddr, port)); 247 } else { 248 /* Use specified HostkeyAlgorithms exactly */ 249 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 250 compat_pkalg_proposal(options.hostkeyalgorithms); 251 } 252 253 if (options.rekey_limit || options.rekey_interval) 254 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 255 options.rekey_interval); 256 257 /* start key exchange */ 258 if ((r = kex_setup(ssh, myproposal)) != 0) 259 fatal("kex_setup: %s", ssh_err(r)); 260 #ifdef WITH_OPENSSL 261 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 262 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 263 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 264 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 265 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 266 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 267 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 268 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 269 #endif 270 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 271 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 272 ssh->kex->verify_host_key=&verify_host_key_callback; 273 274 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 275 276 /* remove ext-info from the KEX proposals for rekeying */ 277 myproposal[PROPOSAL_KEX_ALGS] = 278 compat_kex_proposal(options.kex_algorithms); 279 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 280 fatal("kex_prop2buf: %s", ssh_err(r)); 281 282 session_id2 = ssh->kex->session_id; 283 session_id2_len = ssh->kex->session_id_len; 284 285 #ifdef DEBUG_KEXDH 286 /* send 1st encrypted/maced/compressed message */ 287 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 288 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 289 (r = sshpkt_send(ssh)) != 0 || 290 (r = ssh_packet_write_wait(ssh)) != 0) 291 fatal("%s: %s", __func__, ssh_err(r)); 292 #endif 293 } 294 295 /* 296 * Authenticate user 297 */ 298 299 typedef struct cauthctxt Authctxt; 300 typedef struct cauthmethod Authmethod; 301 typedef struct identity Identity; 302 typedef struct idlist Idlist; 303 304 struct identity { 305 TAILQ_ENTRY(identity) next; 306 int agent_fd; /* >=0 if agent supports key */ 307 struct sshkey *key; /* public/private key */ 308 char *filename; /* comment for agent-only keys */ 309 int tried; 310 int isprivate; /* key points to the private key */ 311 int userprovided; 312 }; 313 TAILQ_HEAD(idlist, identity); 314 315 struct cauthctxt { 316 const char *server_user; 317 const char *local_user; 318 const char *host; 319 const char *service; 320 struct cauthmethod *method; 321 sig_atomic_t success; 322 char *authlist; 323 #ifdef GSSAPI 324 /* gssapi */ 325 gss_OID_set gss_supported_mechs; 326 u_int mech_tried; 327 #endif 328 /* pubkey */ 329 struct idlist keys; 330 int agent_fd; 331 /* hostbased */ 332 Sensitive *sensitive; 333 char *oktypes, *ktypes; 334 const char *active_ktype; 335 /* kbd-interactive */ 336 int info_req_seen; 337 int attempt_kbdint; 338 /* password */ 339 int attempt_passwd; 340 /* generic */ 341 void *methoddata; 342 }; 343 344 struct cauthmethod { 345 char *name; /* string to compare against server's list */ 346 int (*userauth)(struct ssh *ssh); 347 void (*cleanup)(struct ssh *ssh); 348 int *enabled; /* flag in option struct that enables method */ 349 int *batch_flag; /* flag in option struct that disables method */ 350 }; 351 352 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 353 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 354 static int input_userauth_success(int, u_int32_t, struct ssh *); 355 static int input_userauth_failure(int, u_int32_t, struct ssh *); 356 static int input_userauth_banner(int, u_int32_t, struct ssh *); 357 static int input_userauth_error(int, u_int32_t, struct ssh *); 358 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 359 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 360 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 361 362 static int userauth_none(struct ssh *); 363 static int userauth_pubkey(struct ssh *); 364 static int userauth_passwd(struct ssh *); 365 static int userauth_kbdint(struct ssh *); 366 static int userauth_hostbased(struct ssh *); 367 368 #ifdef GSSAPI 369 static int userauth_gssapi(struct ssh *); 370 static void userauth_gssapi_cleanup(struct ssh *); 371 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 372 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 373 static int input_gssapi_error(int, u_int32_t, struct ssh *); 374 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 375 #endif 376 377 void userauth(struct ssh *, char *); 378 379 static void pubkey_cleanup(struct ssh *); 380 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 381 static void pubkey_prepare(Authctxt *); 382 static void pubkey_reset(Authctxt *); 383 static struct sshkey *load_identity_file(Identity *); 384 385 static Authmethod *authmethod_get(char *authlist); 386 static Authmethod *authmethod_lookup(const char *name); 387 static char *authmethods_get(void); 388 389 Authmethod authmethods[] = { 390 #ifdef GSSAPI 391 {"gssapi-with-mic", 392 userauth_gssapi, 393 userauth_gssapi_cleanup, 394 &options.gss_authentication, 395 NULL}, 396 #endif 397 {"hostbased", 398 userauth_hostbased, 399 NULL, 400 &options.hostbased_authentication, 401 NULL}, 402 {"publickey", 403 userauth_pubkey, 404 NULL, 405 &options.pubkey_authentication, 406 NULL}, 407 {"keyboard-interactive", 408 userauth_kbdint, 409 NULL, 410 &options.kbd_interactive_authentication, 411 &options.batch_mode}, 412 {"password", 413 userauth_passwd, 414 NULL, 415 &options.password_authentication, 416 &options.batch_mode}, 417 {"none", 418 userauth_none, 419 NULL, 420 NULL, 421 NULL}, 422 {NULL, NULL, NULL, NULL, NULL} 423 }; 424 425 void 426 ssh_userauth2(struct ssh *ssh, const char *local_user, 427 const char *server_user, char *host, Sensitive *sensitive) 428 { 429 Authctxt authctxt; 430 int r; 431 432 if (options.challenge_response_authentication) 433 options.kbd_interactive_authentication = 1; 434 if (options.preferred_authentications == NULL) 435 options.preferred_authentications = authmethods_get(); 436 437 /* setup authentication context */ 438 memset(&authctxt, 0, sizeof(authctxt)); 439 authctxt.server_user = server_user; 440 authctxt.local_user = local_user; 441 authctxt.host = host; 442 authctxt.service = "ssh-connection"; /* service name */ 443 authctxt.success = 0; 444 authctxt.method = authmethod_lookup("none"); 445 authctxt.authlist = NULL; 446 authctxt.methoddata = NULL; 447 authctxt.sensitive = sensitive; 448 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 449 authctxt.info_req_seen = 0; 450 authctxt.attempt_kbdint = 0; 451 authctxt.attempt_passwd = 0; 452 #if GSSAPI 453 authctxt.gss_supported_mechs = NULL; 454 authctxt.mech_tried = 0; 455 #endif 456 authctxt.agent_fd = -1; 457 pubkey_prepare(&authctxt); 458 if (authctxt.method == NULL) { 459 fatal("%s: internal error: cannot send userauth none request", 460 __func__); 461 } 462 463 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 464 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 465 (r = sshpkt_send(ssh)) != 0) 466 fatal("%s: %s", __func__, ssh_err(r)); 467 468 ssh->authctxt = &authctxt; 469 ssh_dispatch_init(ssh, &input_userauth_error); 470 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 471 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 472 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 473 pubkey_cleanup(ssh); 474 ssh->authctxt = NULL; 475 476 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 477 478 if (!authctxt.success) 479 fatal("Authentication failed."); 480 debug("Authentication succeeded (%s).", authctxt.method->name); 481 } 482 483 /* ARGSUSED */ 484 static int 485 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 486 { 487 int r; 488 489 if (ssh_packet_remaining(ssh) > 0) { 490 char *reply; 491 492 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 493 goto out; 494 debug2("service_accept: %s", reply); 495 free(reply); 496 } else { 497 debug2("buggy server: service_accept w/o service"); 498 } 499 if ((r = sshpkt_get_end(ssh)) != 0) 500 goto out; 501 debug("SSH2_MSG_SERVICE_ACCEPT received"); 502 503 /* initial userauth request */ 504 userauth_none(ssh); 505 506 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 507 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 508 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 509 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 510 r = 0; 511 out: 512 return r; 513 } 514 515 /* ARGSUSED */ 516 static int 517 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 518 { 519 return kex_input_ext_info(type, seqnr, ssh); 520 } 521 522 void 523 userauth(struct ssh *ssh, char *authlist) 524 { 525 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 526 527 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 528 authctxt->method->cleanup(ssh); 529 530 free(authctxt->methoddata); 531 authctxt->methoddata = NULL; 532 if (authlist == NULL) { 533 authlist = authctxt->authlist; 534 } else { 535 free(authctxt->authlist); 536 authctxt->authlist = authlist; 537 } 538 for (;;) { 539 Authmethod *method = authmethod_get(authlist); 540 if (method == NULL) 541 fatal("%s@%s: Permission denied (%s).", 542 authctxt->server_user, authctxt->host, authlist); 543 authctxt->method = method; 544 545 /* reset the per method handler */ 546 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 547 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 548 549 /* and try new method */ 550 if (method->userauth(ssh) != 0) { 551 debug2("we sent a %s packet, wait for reply", method->name); 552 break; 553 } else { 554 debug2("we did not send a packet, disable method"); 555 method->enabled = NULL; 556 } 557 } 558 } 559 560 /* ARGSUSED */ 561 static int 562 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 563 { 564 fatal("%s: bad message during authentication: type %d", __func__, type); 565 return 0; 566 } 567 568 /* ARGSUSED */ 569 static int 570 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 571 { 572 char *msg = NULL; 573 size_t len; 574 int r; 575 576 debug3("%s", __func__); 577 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 578 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 579 goto out; 580 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 581 fmprintf(stderr, "%s", msg); 582 r = 0; 583 out: 584 free(msg); 585 return r; 586 } 587 588 /* ARGSUSED */ 589 static int 590 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 591 { 592 Authctxt *authctxt = ssh->authctxt; 593 594 if (authctxt == NULL) 595 fatal("%s: no authentication context", __func__); 596 free(authctxt->authlist); 597 authctxt->authlist = NULL; 598 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 599 authctxt->method->cleanup(ssh); 600 free(authctxt->methoddata); 601 authctxt->methoddata = NULL; 602 authctxt->success = 1; /* break out */ 603 return 0; 604 } 605 606 #if 0 607 static int 608 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 609 { 610 Authctxt *authctxt = ssh->authctxt; 611 612 if (authctxt == NULL) 613 fatal("%s: no authentication context", __func__); 614 615 fatal("Unexpected authentication success during %s.", 616 authctxt->method->name); 617 return 0; 618 } 619 #endif 620 621 /* ARGSUSED */ 622 static int 623 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 624 { 625 Authctxt *authctxt = ssh->authctxt; 626 char *authlist = NULL; 627 u_char partial; 628 629 if (authctxt == NULL) 630 fatal("input_userauth_failure: no authentication context"); 631 632 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 633 sshpkt_get_u8(ssh, &partial) != 0 || 634 sshpkt_get_end(ssh) != 0) 635 goto out; 636 637 if (partial != 0) { 638 verbose("Authenticated with partial success."); 639 /* reset state */ 640 pubkey_reset(authctxt); 641 } 642 debug("Authentications that can continue: %s", authlist); 643 644 userauth(ssh, authlist); 645 authlist = NULL; 646 out: 647 free(authlist); 648 return 0; 649 } 650 651 /* 652 * Format an identity for logging including filename, key type, fingerprint 653 * and location (agent, etc.). Caller must free. 654 */ 655 static char * 656 format_identity(Identity *id) 657 { 658 char *fp = NULL, *ret = NULL; 659 const char *note = ""; 660 661 if (id->key != NULL) { 662 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 663 SSH_FP_DEFAULT); 664 } 665 if (id->key) { 666 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 667 note = " token"; 668 else if (sshkey_is_sk(id->key)) 669 note = " authenticator"; 670 } 671 xasprintf(&ret, "%s %s%s%s%s%s%s", 672 id->filename, 673 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 674 fp ? fp : "", 675 id->userprovided ? " explicit" : "", note, 676 id->agent_fd != -1 ? " agent" : ""); 677 free(fp); 678 return ret; 679 } 680 681 /* ARGSUSED */ 682 static int 683 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 684 { 685 Authctxt *authctxt = ssh->authctxt; 686 struct sshkey *key = NULL; 687 Identity *id = NULL; 688 int pktype, found = 0, sent = 0; 689 size_t blen; 690 char *pkalg = NULL, *fp = NULL, *ident = NULL; 691 u_char *pkblob = NULL; 692 int r; 693 694 if (authctxt == NULL) 695 fatal("input_userauth_pk_ok: no authentication context"); 696 697 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 698 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 699 (r = sshpkt_get_end(ssh)) != 0) 700 goto done; 701 702 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 703 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 704 goto done; 705 } 706 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 707 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 708 goto done; 709 } 710 if (key->type != pktype) { 711 error("input_userauth_pk_ok: type mismatch " 712 "for decoded key (received %d, expected %d)", 713 key->type, pktype); 714 goto done; 715 } 716 717 /* 718 * search keys in the reverse order, because last candidate has been 719 * moved to the end of the queue. this also avoids confusion by 720 * duplicate keys 721 */ 722 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 723 if (sshkey_equal(key, id->key)) { 724 found = 1; 725 break; 726 } 727 } 728 if (!found || id == NULL) { 729 fp = sshkey_fingerprint(key, options.fingerprint_hash, 730 SSH_FP_DEFAULT); 731 error("%s: server replied with unknown key: %s %s", __func__, 732 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 733 goto done; 734 } 735 ident = format_identity(id); 736 debug("Server accepts key: %s", ident); 737 sent = sign_and_send_pubkey(ssh, id); 738 r = 0; 739 done: 740 sshkey_free(key); 741 free(ident); 742 free(fp); 743 free(pkalg); 744 free(pkblob); 745 746 /* try another method if we did not send a packet */ 747 if (r == 0 && sent == 0) 748 userauth(ssh, NULL); 749 return r; 750 } 751 752 #ifdef GSSAPI 753 static int 754 userauth_gssapi(struct ssh *ssh) 755 { 756 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 757 Gssctxt *gssctxt = NULL; 758 OM_uint32 min; 759 int r, ok = 0; 760 gss_OID mech = NULL; 761 762 /* Try one GSSAPI method at a time, rather than sending them all at 763 * once. */ 764 765 if (authctxt->gss_supported_mechs == NULL) 766 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 767 768 /* Check to see whether the mechanism is usable before we offer it */ 769 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 770 !ok) { 771 mech = &authctxt->gss_supported_mechs-> 772 elements[authctxt->mech_tried]; 773 /* My DER encoding requires length<128 */ 774 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 775 mech, authctxt->host)) { 776 ok = 1; /* Mechanism works */ 777 } else { 778 authctxt->mech_tried++; 779 } 780 } 781 782 if (!ok || mech == NULL) 783 return 0; 784 785 authctxt->methoddata=(void *)gssctxt; 786 787 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 788 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 789 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 790 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 791 (r = sshpkt_put_u32(ssh, 1)) != 0 || 792 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 793 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 794 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 795 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 796 (r = sshpkt_send(ssh)) != 0) 797 fatal("%s: %s", __func__, ssh_err(r)); 798 799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 800 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 801 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 802 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 803 804 authctxt->mech_tried++; /* Move along to next candidate */ 805 806 return 1; 807 } 808 809 static void 810 userauth_gssapi_cleanup(struct ssh *ssh) 811 { 812 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 813 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 814 815 ssh_gssapi_delete_ctx(&gssctxt); 816 authctxt->methoddata = NULL; 817 818 free(authctxt->gss_supported_mechs); 819 authctxt->gss_supported_mechs = NULL; 820 } 821 822 static OM_uint32 823 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 824 { 825 Authctxt *authctxt = ssh->authctxt; 826 Gssctxt *gssctxt = authctxt->methoddata; 827 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 828 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 829 gss_buffer_desc gssbuf; 830 OM_uint32 status, ms, flags; 831 int r; 832 833 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 834 recv_tok, &send_tok, &flags); 835 836 if (send_tok.length > 0) { 837 u_char type = GSS_ERROR(status) ? 838 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 839 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 840 841 if ((r = sshpkt_start(ssh, type)) != 0 || 842 (r = sshpkt_put_string(ssh, send_tok.value, 843 send_tok.length)) != 0 || 844 (r = sshpkt_send(ssh)) != 0) 845 fatal("%s: %s", __func__, ssh_err(r)); 846 847 gss_release_buffer(&ms, &send_tok); 848 } 849 850 if (status == GSS_S_COMPLETE) { 851 /* send either complete or MIC, depending on mechanism */ 852 if (!(flags & GSS_C_INTEG_FLAG)) { 853 if ((r = sshpkt_start(ssh, 854 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 855 (r = sshpkt_send(ssh)) != 0) 856 fatal("%s: %s", __func__, ssh_err(r)); 857 } else { 858 struct sshbuf *b; 859 860 if ((b = sshbuf_new()) == NULL) 861 fatal("%s: sshbuf_new failed", __func__); 862 ssh_gssapi_buildmic(b, authctxt->server_user, 863 authctxt->service, "gssapi-with-mic"); 864 865 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 866 fatal("%s: sshbuf_mutable_ptr failed", __func__); 867 gssbuf.length = sshbuf_len(b); 868 869 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 870 871 if (!GSS_ERROR(status)) { 872 if ((r = sshpkt_start(ssh, 873 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 874 (r = sshpkt_put_string(ssh, mic.value, 875 mic.length)) != 0 || 876 (r = sshpkt_send(ssh)) != 0) 877 fatal("%s: %s", __func__, ssh_err(r)); 878 } 879 880 sshbuf_free(b); 881 gss_release_buffer(&ms, &mic); 882 } 883 } 884 885 return status; 886 } 887 888 /* ARGSUSED */ 889 static int 890 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 891 { 892 Authctxt *authctxt = ssh->authctxt; 893 Gssctxt *gssctxt; 894 size_t oidlen; 895 u_char *oidv = NULL; 896 int r; 897 898 if (authctxt == NULL) 899 fatal("input_gssapi_response: no authentication context"); 900 gssctxt = authctxt->methoddata; 901 902 /* Setup our OID */ 903 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 904 goto done; 905 906 if (oidlen <= 2 || 907 oidv[0] != SSH_GSS_OIDTYPE || 908 oidv[1] != oidlen - 2) { 909 debug("Badly encoded mechanism OID received"); 910 userauth(ssh, NULL); 911 goto ok; 912 } 913 914 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 915 fatal("Server returned different OID than expected"); 916 917 if ((r = sshpkt_get_end(ssh)) != 0) 918 goto done; 919 920 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 921 /* Start again with next method on list */ 922 debug("Trying to start again"); 923 userauth(ssh, NULL); 924 goto ok; 925 } 926 ok: 927 r = 0; 928 done: 929 free(oidv); 930 return r; 931 } 932 933 /* ARGSUSED */ 934 static int 935 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 936 { 937 Authctxt *authctxt = ssh->authctxt; 938 gss_buffer_desc recv_tok; 939 u_char *p = NULL; 940 size_t len; 941 OM_uint32 status; 942 int r; 943 944 if (authctxt == NULL) 945 fatal("input_gssapi_response: no authentication context"); 946 947 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 948 (r = sshpkt_get_end(ssh)) != 0) 949 goto out; 950 951 recv_tok.value = p; 952 recv_tok.length = len; 953 status = process_gssapi_token(ssh, &recv_tok); 954 955 /* Start again with the next method in the list */ 956 if (GSS_ERROR(status)) { 957 userauth(ssh, NULL); 958 /* ok */ 959 } 960 r = 0; 961 out: 962 free(p); 963 return r; 964 } 965 966 /* ARGSUSED */ 967 static int 968 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 969 { 970 Authctxt *authctxt = ssh->authctxt; 971 Gssctxt *gssctxt; 972 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 973 gss_buffer_desc recv_tok; 974 OM_uint32 ms; 975 u_char *p = NULL; 976 size_t len; 977 int r; 978 979 if (authctxt == NULL) 980 fatal("input_gssapi_response: no authentication context"); 981 gssctxt = authctxt->methoddata; 982 983 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 984 (r = sshpkt_get_end(ssh)) != 0) { 985 free(p); 986 return r; 987 } 988 989 /* Stick it into GSSAPI and see what it says */ 990 recv_tok.value = p; 991 recv_tok.length = len; 992 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 993 &recv_tok, &send_tok, NULL); 994 free(p); 995 gss_release_buffer(&ms, &send_tok); 996 997 /* Server will be returning a failed packet after this one */ 998 return 0; 999 } 1000 1001 /* ARGSUSED */ 1002 static int 1003 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 1004 { 1005 char *msg = NULL; 1006 char *lang = NULL; 1007 int r; 1008 1009 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 1010 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 1011 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 1012 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1013 goto out; 1014 r = sshpkt_get_end(ssh); 1015 debug("Server GSSAPI Error:\n%s", msg); 1016 out: 1017 free(msg); 1018 free(lang); 1019 return r; 1020 } 1021 #endif /* GSSAPI */ 1022 1023 static int 1024 userauth_none(struct ssh *ssh) 1025 { 1026 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1027 int r; 1028 1029 /* initial userauth request */ 1030 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1031 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1032 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1033 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1034 (r = sshpkt_send(ssh)) != 0) 1035 fatal("%s: %s", __func__, ssh_err(r)); 1036 return 1; 1037 } 1038 1039 static int 1040 userauth_passwd(struct ssh *ssh) 1041 { 1042 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1043 char *password, *prompt = NULL; 1044 const char *host = options.host_key_alias ? options.host_key_alias : 1045 authctxt->host; 1046 int r; 1047 1048 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1049 return 0; 1050 1051 if (authctxt->attempt_passwd != 1) 1052 error("Permission denied, please try again."); 1053 1054 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1055 password = read_passphrase(prompt, 0); 1056 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1057 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1058 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1059 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1060 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1061 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1062 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1063 (r = sshpkt_send(ssh)) != 0) 1064 fatal("%s: %s", __func__, ssh_err(r)); 1065 1066 free(prompt); 1067 if (password != NULL) 1068 freezero(password, strlen(password)); 1069 1070 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1071 &input_userauth_passwd_changereq); 1072 1073 return 1; 1074 } 1075 1076 /* 1077 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1078 */ 1079 /* ARGSUSED */ 1080 static int 1081 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1082 { 1083 Authctxt *authctxt = ssh->authctxt; 1084 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1085 char prompt[256]; 1086 const char *host; 1087 int r; 1088 1089 debug2("input_userauth_passwd_changereq"); 1090 1091 if (authctxt == NULL) 1092 fatal("input_userauth_passwd_changereq: " 1093 "no authentication context"); 1094 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1095 1096 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1097 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1098 goto out; 1099 if (strlen(info) > 0) 1100 logit("%s", info); 1101 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1102 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1103 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1104 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1105 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1106 goto out; 1107 1108 snprintf(prompt, sizeof(prompt), 1109 "Enter %.30s@%.128s's old password: ", 1110 authctxt->server_user, host); 1111 password = read_passphrase(prompt, 0); 1112 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1113 goto out; 1114 1115 freezero(password, strlen(password)); 1116 password = NULL; 1117 while (password == NULL) { 1118 snprintf(prompt, sizeof(prompt), 1119 "Enter %.30s@%.128s's new password: ", 1120 authctxt->server_user, host); 1121 password = read_passphrase(prompt, RP_ALLOW_EOF); 1122 if (password == NULL) { 1123 /* bail out */ 1124 r = 0; 1125 goto out; 1126 } 1127 snprintf(prompt, sizeof(prompt), 1128 "Retype %.30s@%.128s's new password: ", 1129 authctxt->server_user, host); 1130 retype = read_passphrase(prompt, 0); 1131 if (strcmp(password, retype) != 0) { 1132 freezero(password, strlen(password)); 1133 logit("Mismatch; try again, EOF to quit."); 1134 password = NULL; 1135 } 1136 freezero(retype, strlen(retype)); 1137 } 1138 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1139 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1140 (r = sshpkt_send(ssh)) != 0) 1141 goto out; 1142 1143 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1144 &input_userauth_passwd_changereq); 1145 r = 0; 1146 out: 1147 if (password) 1148 freezero(password, strlen(password)); 1149 free(info); 1150 free(lang); 1151 return r; 1152 } 1153 1154 /* 1155 * Select an algorithm for publickey signatures. 1156 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1157 * 1158 * Call with ssh==NULL to ignore server-sig-algs extension list and 1159 * only attempt with the key's base signature type. 1160 */ 1161 static char * 1162 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1163 { 1164 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1165 1166 /* 1167 * The signature algorithm will only differ from the key algorithm 1168 * for RSA keys/certs and when the server advertises support for 1169 * newer (SHA2) algorithms. 1170 */ 1171 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1172 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1173 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1174 /* Filter base key signature alg against our configuration */ 1175 return match_list(sshkey_ssh_name(key), 1176 options.pubkey_key_types, NULL); 1177 } 1178 1179 /* 1180 * For RSA keys/certs, since these might have a different sig type: 1181 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1182 * that also appears in the supported signature algorithms list from 1183 * the server. 1184 */ 1185 oallowed = allowed = xstrdup(options.pubkey_key_types); 1186 while ((cp = strsep(&allowed, ",")) != NULL) { 1187 if (sshkey_type_from_name(cp) != key->type) 1188 continue; 1189 tmp = match_list(sshkey_sigalg_by_name(cp), 1190 ssh->kex->server_sig_algs, NULL); 1191 if (tmp != NULL) 1192 alg = xstrdup(cp); 1193 free(tmp); 1194 if (alg != NULL) 1195 break; 1196 } 1197 free(oallowed); 1198 return alg; 1199 } 1200 1201 static int 1202 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1203 const u_char *data, size_t datalen, u_int compat, const char *alg) 1204 { 1205 struct sshkey *sign_key = NULL, *prv = NULL; 1206 int r = SSH_ERR_INTERNAL_ERROR; 1207 struct notifier_ctx *notifier = NULL; 1208 char *fp = NULL, *pin = NULL, *prompt = NULL; 1209 1210 *sigp = NULL; 1211 *lenp = 0; 1212 1213 /* The agent supports this key. */ 1214 if (id->key != NULL && id->agent_fd != -1) { 1215 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1216 data, datalen, alg, compat); 1217 } 1218 1219 /* 1220 * We have already loaded the private key or the private key is 1221 * stored in external hardware. 1222 */ 1223 if (id->key != NULL && 1224 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1225 sign_key = id->key; 1226 } else { 1227 /* Load the private key from the file. */ 1228 if ((prv = load_identity_file(id)) == NULL) 1229 return SSH_ERR_KEY_NOT_FOUND; 1230 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1231 error("%s: private key %s contents do not match public", 1232 __func__, id->filename); 1233 r = SSH_ERR_KEY_NOT_FOUND; 1234 goto out; 1235 } 1236 sign_key = prv; 1237 if (sshkey_is_sk(sign_key)) { 1238 if ((sign_key->sk_flags & 1239 SSH_SK_USER_VERIFICATION_REQD)) { 1240 xasprintf(&prompt, "Enter PIN for %s key %s: ", 1241 sshkey_type(sign_key), id->filename); 1242 pin = read_passphrase(prompt, 0); 1243 } 1244 if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1245 /* XXX should batch mode just skip these? */ 1246 if ((fp = sshkey_fingerprint(sign_key, 1247 options.fingerprint_hash, 1248 SSH_FP_DEFAULT)) == NULL) 1249 fatal("%s: fingerprint", __func__); 1250 notifier = notify_start(options.batch_mode, 1251 "Confirm user presence for key %s %s", 1252 sshkey_type(sign_key), fp); 1253 free(fp); 1254 } 1255 } 1256 } 1257 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1258 alg, options.sk_provider, pin, compat)) != 0) { 1259 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1260 goto out; 1261 } 1262 /* 1263 * PKCS#11 tokens may not support all signature algorithms, 1264 * so check what we get back. 1265 */ 1266 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1267 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1268 goto out; 1269 } 1270 /* success */ 1271 r = 0; 1272 out: 1273 free(prompt); 1274 if (pin != NULL) 1275 freezero(pin, strlen(pin)); 1276 notify_complete(notifier); 1277 sshkey_free(prv); 1278 return r; 1279 } 1280 1281 static int 1282 id_filename_matches(Identity *id, Identity *private_id) 1283 { 1284 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1285 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1286 size_t i, slen; 1287 1288 if (strcmp(id->filename, private_id->filename) == 0) 1289 return 1; 1290 for (i = 0; suffixes[i]; i++) { 1291 slen = strlen(suffixes[i]); 1292 if (len > slen && plen == len - slen && 1293 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1294 memcmp(id->filename, private_id->filename, plen) == 0) 1295 return 1; 1296 } 1297 return 0; 1298 } 1299 1300 static int 1301 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1302 { 1303 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1304 struct sshbuf *b = NULL; 1305 Identity *private_id, *sign_id = NULL; 1306 u_char *signature = NULL; 1307 size_t slen = 0, skip = 0; 1308 int r, fallback_sigtype, sent = 0; 1309 char *alg = NULL, *fp = NULL; 1310 const char *loc = ""; 1311 1312 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1313 SSH_FP_DEFAULT)) == NULL) 1314 return 0; 1315 1316 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1317 1318 /* 1319 * If the key is an certificate, try to find a matching private key 1320 * and use it to complete the signature. 1321 * If no such private key exists, fall back to trying the certificate 1322 * key itself in case it has a private half already loaded. 1323 * This will try to set sign_id to the private key that will perform 1324 * the signature. 1325 */ 1326 if (sshkey_is_cert(id->key)) { 1327 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1328 if (sshkey_equal_public(id->key, private_id->key) && 1329 id->key->type != private_id->key->type) { 1330 sign_id = private_id; 1331 break; 1332 } 1333 } 1334 /* 1335 * Exact key matches are preferred, but also allow 1336 * filename matches for non-PKCS#11/agent keys that 1337 * didn't load public keys. This supports the case 1338 * of keeping just a private key file and public 1339 * certificate on disk. 1340 */ 1341 if (sign_id == NULL && 1342 !id->isprivate && id->agent_fd == -1 && 1343 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1344 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1345 if (private_id->key == NULL && 1346 id_filename_matches(id, private_id)) { 1347 sign_id = private_id; 1348 break; 1349 } 1350 } 1351 } 1352 if (sign_id != NULL) { 1353 debug2("%s: using private key \"%s\"%s for " 1354 "certificate", __func__, id->filename, 1355 id->agent_fd != -1 ? " from agent" : ""); 1356 } else { 1357 debug("%s: no separate private key for certificate " 1358 "\"%s\"", __func__, id->filename); 1359 } 1360 } 1361 1362 /* 1363 * If the above didn't select another identity to do the signing 1364 * then default to the one we started with. 1365 */ 1366 if (sign_id == NULL) 1367 sign_id = id; 1368 1369 /* assemble and sign data */ 1370 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1371 free(alg); 1372 slen = 0; 1373 signature = NULL; 1374 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1375 id->key)) == NULL) { 1376 error("%s: no mutual signature supported", __func__); 1377 goto out; 1378 } 1379 debug3("%s: signing using %s %s", __func__, alg, fp); 1380 1381 sshbuf_free(b); 1382 if ((b = sshbuf_new()) == NULL) 1383 fatal("%s: sshbuf_new failed", __func__); 1384 if (datafellows & SSH_OLD_SESSIONID) { 1385 if ((r = sshbuf_put(b, session_id2, 1386 session_id2_len)) != 0) { 1387 fatal("%s: sshbuf_put: %s", 1388 __func__, ssh_err(r)); 1389 } 1390 } else { 1391 if ((r = sshbuf_put_string(b, session_id2, 1392 session_id2_len)) != 0) { 1393 fatal("%s: sshbuf_put_string: %s", 1394 __func__, ssh_err(r)); 1395 } 1396 } 1397 skip = sshbuf_len(b); 1398 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1399 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1400 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1401 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1402 (r = sshbuf_put_u8(b, 1)) != 0 || 1403 (r = sshbuf_put_cstring(b, alg)) != 0 || 1404 (r = sshkey_puts(id->key, b)) != 0) { 1405 fatal("%s: assemble signed data: %s", 1406 __func__, ssh_err(r)); 1407 } 1408 1409 /* generate signature */ 1410 r = identity_sign(sign_id, &signature, &slen, 1411 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1412 if (r == 0) 1413 break; 1414 else if (r == SSH_ERR_KEY_NOT_FOUND) 1415 goto out; /* soft failure */ 1416 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1417 !fallback_sigtype) { 1418 if (sign_id->agent_fd != -1) 1419 loc = "agent "; 1420 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1421 loc = "token "; 1422 logit("%skey %s %s returned incorrect signature type", 1423 loc, sshkey_type(id->key), fp); 1424 continue; 1425 } 1426 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1427 sshkey_type(sign_id->key), sign_id->filename, 1428 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1429 goto out; 1430 } 1431 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1432 fatal("%s: no signature", __func__); 1433 1434 /* append signature */ 1435 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1436 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1437 1438 #ifdef DEBUG_PK 1439 sshbuf_dump(b, stderr); 1440 #endif 1441 /* skip session id and packet type */ 1442 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1443 fatal("%s: consume: %s", __func__, ssh_err(r)); 1444 1445 /* put remaining data from buffer into packet */ 1446 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1447 (r = sshpkt_putb(ssh, b)) != 0 || 1448 (r = sshpkt_send(ssh)) != 0) 1449 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1450 1451 /* success */ 1452 sent = 1; 1453 1454 out: 1455 free(fp); 1456 free(alg); 1457 sshbuf_free(b); 1458 freezero(signature, slen); 1459 return sent; 1460 } 1461 1462 static int 1463 send_pubkey_test(struct ssh *ssh, Identity *id) 1464 { 1465 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1466 u_char *blob = NULL; 1467 char *alg = NULL; 1468 size_t bloblen; 1469 u_int have_sig = 0; 1470 int sent = 0, r; 1471 1472 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1473 debug("%s: no mutual signature algorithm", __func__); 1474 goto out; 1475 } 1476 1477 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1478 /* we cannot handle this key */ 1479 debug3("%s: cannot handle key", __func__); 1480 goto out; 1481 } 1482 /* register callback for USERAUTH_PK_OK message */ 1483 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1484 1485 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1486 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1487 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1488 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1489 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1490 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1491 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1492 (r = sshpkt_send(ssh)) != 0) 1493 fatal("%s: %s", __func__, ssh_err(r)); 1494 sent = 1; 1495 1496 out: 1497 free(alg); 1498 free(blob); 1499 return sent; 1500 } 1501 1502 static struct sshkey * 1503 load_identity_file(Identity *id) 1504 { 1505 struct sshkey *private = NULL; 1506 char prompt[300], *passphrase, *comment; 1507 int r, quit = 0, i; 1508 struct stat st; 1509 1510 if (stat(id->filename, &st) == -1) { 1511 do_log2(id->userprovided ? 1512 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3, 1513 "no such identity: %s: %s", id->filename, strerror(errno)); 1514 return NULL; 1515 } 1516 snprintf(prompt, sizeof prompt, 1517 "Enter passphrase for key '%.100s': ", id->filename); 1518 for (i = 0; i <= options.number_of_password_prompts; i++) { 1519 if (i == 0) 1520 passphrase = ""; 1521 else { 1522 passphrase = read_passphrase(prompt, 0); 1523 if (*passphrase == '\0') { 1524 debug2("no passphrase given, try next key"); 1525 free(passphrase); 1526 break; 1527 } 1528 } 1529 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1530 passphrase, &private, &comment))) { 1531 case 0: 1532 break; 1533 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1534 if (options.batch_mode) { 1535 quit = 1; 1536 break; 1537 } 1538 if (i != 0) 1539 debug2("bad passphrase given, try again..."); 1540 break; 1541 case SSH_ERR_SYSTEM_ERROR: 1542 if (errno == ENOENT) { 1543 debug2("Load key \"%s\": %s", 1544 id->filename, ssh_err(r)); 1545 quit = 1; 1546 break; 1547 } 1548 /* FALLTHROUGH */ 1549 default: 1550 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1551 quit = 1; 1552 break; 1553 } 1554 if (private != NULL && sshkey_is_sk(private) && 1555 options.sk_provider == NULL) { 1556 debug("key \"%s\" is an authenticator-hosted key, " 1557 "but no provider specified", id->filename); 1558 sshkey_free(private); 1559 private = NULL; 1560 quit = 1; 1561 } 1562 if (!quit && private != NULL && id->agent_fd == -1 && 1563 !(id->key && id->isprivate)) 1564 maybe_add_key_to_agent(id->filename, private, comment, 1565 passphrase); 1566 if (i > 0) 1567 freezero(passphrase, strlen(passphrase)); 1568 free(comment); 1569 if (private != NULL || quit) 1570 break; 1571 } 1572 return private; 1573 } 1574 1575 static int 1576 key_type_allowed_by_config(struct sshkey *key) 1577 { 1578 if (match_pattern_list(sshkey_ssh_name(key), 1579 options.pubkey_key_types, 0) == 1) 1580 return 1; 1581 1582 /* RSA keys/certs might be allowed by alternate signature types */ 1583 switch (key->type) { 1584 case KEY_RSA: 1585 if (match_pattern_list("rsa-sha2-512", 1586 options.pubkey_key_types, 0) == 1) 1587 return 1; 1588 if (match_pattern_list("rsa-sha2-256", 1589 options.pubkey_key_types, 0) == 1) 1590 return 1; 1591 break; 1592 case KEY_RSA_CERT: 1593 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1594 options.pubkey_key_types, 0) == 1) 1595 return 1; 1596 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1597 options.pubkey_key_types, 0) == 1) 1598 return 1; 1599 break; 1600 } 1601 return 0; 1602 } 1603 1604 1605 /* 1606 * try keys in the following order: 1607 * 1. certificates listed in the config file 1608 * 2. other input certificates 1609 * 3. agent keys that are found in the config file 1610 * 4. other agent keys 1611 * 5. keys that are only listed in the config file 1612 */ 1613 static void 1614 pubkey_prepare(Authctxt *authctxt) 1615 { 1616 struct identity *id, *id2, *tmp; 1617 struct idlist agent, files, *preferred; 1618 struct sshkey *key; 1619 int agent_fd = -1, i, r, found; 1620 size_t j; 1621 struct ssh_identitylist *idlist; 1622 char *ident; 1623 1624 TAILQ_INIT(&agent); /* keys from the agent */ 1625 TAILQ_INIT(&files); /* keys from the config file */ 1626 preferred = &authctxt->keys; 1627 TAILQ_INIT(preferred); /* preferred order of keys */ 1628 1629 /* list of keys stored in the filesystem and PKCS#11 */ 1630 for (i = 0; i < options.num_identity_files; i++) { 1631 key = options.identity_keys[i]; 1632 if (key && key->cert && 1633 key->cert->type != SSH2_CERT_TYPE_USER) { 1634 debug("%s: ignoring certificate %s: not a user " 1635 "certificate", __func__, 1636 options.identity_files[i]); 1637 continue; 1638 } 1639 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1640 debug("%s: ignoring authenticator-hosted key %s as no " 1641 "SecurityKeyProvider has been specified", 1642 __func__, options.identity_files[i]); 1643 continue; 1644 } 1645 options.identity_keys[i] = NULL; 1646 id = xcalloc(1, sizeof(*id)); 1647 id->agent_fd = -1; 1648 id->key = key; 1649 id->filename = xstrdup(options.identity_files[i]); 1650 id->userprovided = options.identity_file_userprovided[i]; 1651 TAILQ_INSERT_TAIL(&files, id, next); 1652 } 1653 /* list of certificates specified by user */ 1654 for (i = 0; i < options.num_certificate_files; i++) { 1655 key = options.certificates[i]; 1656 if (!sshkey_is_cert(key) || key->cert == NULL || 1657 key->cert->type != SSH2_CERT_TYPE_USER) { 1658 debug("%s: ignoring certificate %s: not a user " 1659 "certificate", __func__, 1660 options.identity_files[i]); 1661 continue; 1662 } 1663 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1664 debug("%s: ignoring authenticator-hosted key " 1665 "certificate %s as no " 1666 "SecurityKeyProvider has been specified", 1667 __func__, options.identity_files[i]); 1668 continue; 1669 } 1670 id = xcalloc(1, sizeof(*id)); 1671 id->agent_fd = -1; 1672 id->key = key; 1673 id->filename = xstrdup(options.certificate_files[i]); 1674 id->userprovided = options.certificate_file_userprovided[i]; 1675 TAILQ_INSERT_TAIL(preferred, id, next); 1676 } 1677 /* list of keys supported by the agent */ 1678 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1679 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1680 debug("%s: ssh_get_authentication_socket: %s", 1681 __func__, ssh_err(r)); 1682 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1683 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1684 debug("%s: ssh_fetch_identitylist: %s", 1685 __func__, ssh_err(r)); 1686 close(agent_fd); 1687 } else { 1688 for (j = 0; j < idlist->nkeys; j++) { 1689 found = 0; 1690 TAILQ_FOREACH(id, &files, next) { 1691 /* 1692 * agent keys from the config file are 1693 * preferred 1694 */ 1695 if (sshkey_equal(idlist->keys[j], id->key)) { 1696 TAILQ_REMOVE(&files, id, next); 1697 TAILQ_INSERT_TAIL(preferred, id, next); 1698 id->agent_fd = agent_fd; 1699 found = 1; 1700 break; 1701 } 1702 } 1703 if (!found && !options.identities_only) { 1704 id = xcalloc(1, sizeof(*id)); 1705 /* XXX "steals" key/comment from idlist */ 1706 id->key = idlist->keys[j]; 1707 id->filename = idlist->comments[j]; 1708 idlist->keys[j] = NULL; 1709 idlist->comments[j] = NULL; 1710 id->agent_fd = agent_fd; 1711 TAILQ_INSERT_TAIL(&agent, id, next); 1712 } 1713 } 1714 ssh_free_identitylist(idlist); 1715 /* append remaining agent keys */ 1716 TAILQ_CONCAT(preferred, &agent, next); 1717 authctxt->agent_fd = agent_fd; 1718 } 1719 /* Prefer PKCS11 keys that are explicitly listed */ 1720 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1721 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1722 continue; 1723 found = 0; 1724 TAILQ_FOREACH(id2, &files, next) { 1725 if (id2->key == NULL || 1726 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1727 continue; 1728 if (sshkey_equal(id->key, id2->key)) { 1729 TAILQ_REMOVE(&files, id, next); 1730 TAILQ_INSERT_TAIL(preferred, id, next); 1731 found = 1; 1732 break; 1733 } 1734 } 1735 /* If IdentitiesOnly set and key not found then don't use it */ 1736 if (!found && options.identities_only) { 1737 TAILQ_REMOVE(&files, id, next); 1738 freezero(id, sizeof(*id)); 1739 } 1740 } 1741 /* append remaining keys from the config file */ 1742 TAILQ_CONCAT(preferred, &files, next); 1743 /* finally, filter by PubkeyAcceptedKeyTypes */ 1744 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1745 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1746 debug("Skipping %s key %s - " 1747 "not in PubkeyAcceptedKeyTypes", 1748 sshkey_ssh_name(id->key), id->filename); 1749 TAILQ_REMOVE(preferred, id, next); 1750 sshkey_free(id->key); 1751 free(id->filename); 1752 memset(id, 0, sizeof(*id)); 1753 continue; 1754 } 1755 } 1756 /* List the keys we plan on using */ 1757 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1758 ident = format_identity(id); 1759 debug("Will attempt key: %s", ident); 1760 free(ident); 1761 } 1762 debug2("%s: done", __func__); 1763 } 1764 1765 static void 1766 pubkey_cleanup(struct ssh *ssh) 1767 { 1768 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1769 Identity *id; 1770 1771 if (authctxt->agent_fd != -1) { 1772 ssh_close_authentication_socket(authctxt->agent_fd); 1773 authctxt->agent_fd = -1; 1774 } 1775 for (id = TAILQ_FIRST(&authctxt->keys); id; 1776 id = TAILQ_FIRST(&authctxt->keys)) { 1777 TAILQ_REMOVE(&authctxt->keys, id, next); 1778 sshkey_free(id->key); 1779 free(id->filename); 1780 free(id); 1781 } 1782 } 1783 1784 static void 1785 pubkey_reset(Authctxt *authctxt) 1786 { 1787 Identity *id; 1788 1789 TAILQ_FOREACH(id, &authctxt->keys, next) 1790 id->tried = 0; 1791 } 1792 1793 static int 1794 try_identity(Identity *id) 1795 { 1796 if (!id->key) 1797 return (0); 1798 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1799 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1800 debug("Skipped %s key %s for RSA/MD5 server", 1801 sshkey_type(id->key), id->filename); 1802 return (0); 1803 } 1804 return 1; 1805 } 1806 1807 static int 1808 userauth_pubkey(struct ssh *ssh) 1809 { 1810 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1811 Identity *id; 1812 int sent = 0; 1813 char *ident; 1814 1815 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1816 if (id->tried++) 1817 return (0); 1818 /* move key to the end of the queue */ 1819 TAILQ_REMOVE(&authctxt->keys, id, next); 1820 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1821 /* 1822 * send a test message if we have the public key. for 1823 * encrypted keys we cannot do this and have to load the 1824 * private key instead 1825 */ 1826 if (id->key != NULL) { 1827 if (try_identity(id)) { 1828 ident = format_identity(id); 1829 debug("Offering public key: %s", ident); 1830 free(ident); 1831 sent = send_pubkey_test(ssh, id); 1832 } 1833 } else { 1834 debug("Trying private key: %s", id->filename); 1835 id->key = load_identity_file(id); 1836 if (id->key != NULL) { 1837 if (try_identity(id)) { 1838 id->isprivate = 1; 1839 sent = sign_and_send_pubkey(ssh, id); 1840 } 1841 sshkey_free(id->key); 1842 id->key = NULL; 1843 id->isprivate = 0; 1844 } 1845 } 1846 if (sent) 1847 return (sent); 1848 } 1849 return (0); 1850 } 1851 1852 /* 1853 * Send userauth request message specifying keyboard-interactive method. 1854 */ 1855 static int 1856 userauth_kbdint(struct ssh *ssh) 1857 { 1858 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1859 int r; 1860 1861 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1862 return 0; 1863 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1864 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1865 debug3("userauth_kbdint: disable: no info_req_seen"); 1866 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1867 return 0; 1868 } 1869 1870 debug2("userauth_kbdint"); 1871 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1872 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1873 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1874 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1875 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1876 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1877 options.kbd_interactive_devices : "")) != 0 || 1878 (r = sshpkt_send(ssh)) != 0) 1879 fatal("%s: %s", __func__, ssh_err(r)); 1880 1881 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1882 return 1; 1883 } 1884 1885 /* 1886 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1887 */ 1888 static int 1889 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1890 { 1891 Authctxt *authctxt = ssh->authctxt; 1892 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1893 char *response = NULL; 1894 u_char echo = 0; 1895 u_int num_prompts, i; 1896 int r; 1897 1898 debug2("input_userauth_info_req"); 1899 1900 if (authctxt == NULL) 1901 fatal("input_userauth_info_req: no authentication context"); 1902 1903 authctxt->info_req_seen = 1; 1904 1905 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1906 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1907 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1908 goto out; 1909 if (strlen(name) > 0) 1910 logit("%s", name); 1911 if (strlen(inst) > 0) 1912 logit("%s", inst); 1913 1914 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1915 goto out; 1916 /* 1917 * Begin to build info response packet based on prompts requested. 1918 * We commit to providing the correct number of responses, so if 1919 * further on we run into a problem that prevents this, we have to 1920 * be sure and clean this up and send a correct error response. 1921 */ 1922 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1923 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1924 goto out; 1925 1926 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1927 for (i = 0; i < num_prompts; i++) { 1928 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1929 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1930 goto out; 1931 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1932 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1933 goto out; 1934 freezero(response, strlen(response)); 1935 free(prompt); 1936 response = prompt = NULL; 1937 } 1938 /* done with parsing incoming message. */ 1939 if ((r = sshpkt_get_end(ssh)) != 0 || 1940 (r = sshpkt_add_padding(ssh, 64)) != 0) 1941 goto out; 1942 r = sshpkt_send(ssh); 1943 out: 1944 if (response) 1945 freezero(response, strlen(response)); 1946 free(prompt); 1947 free(name); 1948 free(inst); 1949 free(lang); 1950 return r; 1951 } 1952 1953 static int 1954 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1955 const u_char *data, size_t datalen) 1956 { 1957 struct sshbuf *b; 1958 struct stat st; 1959 pid_t pid; 1960 int r, to[2], from[2], status; 1961 int sock = ssh_packet_get_connection_in(ssh); 1962 u_char rversion = 0, version = 2; 1963 void (*osigchld)(int); 1964 1965 *sigp = NULL; 1966 *lenp = 0; 1967 1968 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1969 error("%s: not installed: %s", __func__, strerror(errno)); 1970 return -1; 1971 } 1972 if (fflush(stdout) != 0) { 1973 error("%s: fflush: %s", __func__, strerror(errno)); 1974 return -1; 1975 } 1976 if (pipe(to) == -1) { 1977 error("%s: pipe: %s", __func__, strerror(errno)); 1978 return -1; 1979 } 1980 if (pipe(from) == -1) { 1981 error("%s: pipe: %s", __func__, strerror(errno)); 1982 return -1; 1983 } 1984 if ((pid = fork()) == -1) { 1985 error("%s: fork: %s", __func__, strerror(errno)); 1986 return -1; 1987 } 1988 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1989 if (pid == 0) { 1990 close(from[0]); 1991 if (dup2(from[1], STDOUT_FILENO) == -1) 1992 fatal("%s: dup2: %s", __func__, strerror(errno)); 1993 close(to[1]); 1994 if (dup2(to[0], STDIN_FILENO) == -1) 1995 fatal("%s: dup2: %s", __func__, strerror(errno)); 1996 close(from[1]); 1997 close(to[0]); 1998 1999 if (dup2(sock, STDERR_FILENO + 1) == -1) 2000 fatal("%s: dup2: %s", __func__, strerror(errno)); 2001 sock = STDERR_FILENO + 1; 2002 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 2003 closefrom(sock + 1); 2004 2005 debug3("%s: [child] pid=%ld, exec %s", 2006 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 2007 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 2008 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 2009 strerror(errno)); 2010 } 2011 close(from[1]); 2012 close(to[0]); 2013 sock = STDERR_FILENO + 1; 2014 2015 if ((b = sshbuf_new()) == NULL) 2016 fatal("%s: sshbuf_new failed", __func__); 2017 /* send # of sock, data to be signed */ 2018 if ((r = sshbuf_put_u32(b, sock)) != 0 || 2019 (r = sshbuf_put_string(b, data, datalen)) != 0) 2020 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 2021 if (ssh_msg_send(to[1], version, b) == -1) 2022 fatal("%s: couldn't send request", __func__); 2023 sshbuf_reset(b); 2024 r = ssh_msg_recv(from[0], b); 2025 close(from[0]); 2026 close(to[1]); 2027 if (r < 0) { 2028 error("%s: no reply", __func__); 2029 goto fail; 2030 } 2031 2032 errno = 0; 2033 while (waitpid(pid, &status, 0) == -1) { 2034 if (errno != EINTR) { 2035 error("%s: waitpid %ld: %s", 2036 __func__, (long)pid, strerror(errno)); 2037 goto fail; 2038 } 2039 } 2040 if (!WIFEXITED(status)) { 2041 error("%s: exited abnormally", __func__); 2042 goto fail; 2043 } 2044 if (WEXITSTATUS(status) != 0) { 2045 error("%s: exited with status %d", 2046 __func__, WEXITSTATUS(status)); 2047 goto fail; 2048 } 2049 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2050 error("%s: buffer error: %s", __func__, ssh_err(r)); 2051 goto fail; 2052 } 2053 if (rversion != version) { 2054 error("%s: bad version", __func__); 2055 goto fail; 2056 } 2057 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2058 error("%s: buffer error: %s", __func__, ssh_err(r)); 2059 fail: 2060 ssh_signal(SIGCHLD, osigchld); 2061 sshbuf_free(b); 2062 return -1; 2063 } 2064 ssh_signal(SIGCHLD, osigchld); 2065 sshbuf_free(b); 2066 2067 return 0; 2068 } 2069 2070 static int 2071 userauth_hostbased(struct ssh *ssh) 2072 { 2073 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2074 struct sshkey *private = NULL; 2075 struct sshbuf *b = NULL; 2076 u_char *sig = NULL, *keyblob = NULL; 2077 char *fp = NULL, *chost = NULL, *lname = NULL; 2078 size_t siglen = 0, keylen = 0; 2079 int i, r, success = 0; 2080 2081 if (authctxt->ktypes == NULL) { 2082 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2083 authctxt->ktypes = authctxt->oktypes; 2084 } 2085 2086 /* 2087 * Work through each listed type pattern in HostbasedKeyTypes, 2088 * trying each hostkey that matches the type in turn. 2089 */ 2090 for (;;) { 2091 if (authctxt->active_ktype == NULL) 2092 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2093 if (authctxt->active_ktype == NULL || 2094 *authctxt->active_ktype == '\0') 2095 break; 2096 debug3("%s: trying key type %s", __func__, 2097 authctxt->active_ktype); 2098 2099 /* check for a useful key */ 2100 private = NULL; 2101 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2102 if (authctxt->sensitive->keys[i] == NULL || 2103 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2104 continue; 2105 if (match_pattern_list( 2106 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2107 authctxt->active_ktype, 0) != 1) 2108 continue; 2109 /* we take and free the key */ 2110 private = authctxt->sensitive->keys[i]; 2111 authctxt->sensitive->keys[i] = NULL; 2112 break; 2113 } 2114 /* Found one */ 2115 if (private != NULL) 2116 break; 2117 /* No more keys of this type; advance */ 2118 authctxt->active_ktype = NULL; 2119 } 2120 if (private == NULL) { 2121 free(authctxt->oktypes); 2122 authctxt->oktypes = authctxt->ktypes = NULL; 2123 authctxt->active_ktype = NULL; 2124 debug("No more client hostkeys for hostbased authentication."); 2125 goto out; 2126 } 2127 2128 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2129 SSH_FP_DEFAULT)) == NULL) { 2130 error("%s: sshkey_fingerprint failed", __func__); 2131 goto out; 2132 } 2133 debug("%s: trying hostkey %s %s", 2134 __func__, sshkey_ssh_name(private), fp); 2135 2136 /* figure out a name for the client host */ 2137 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2138 if (lname == NULL) { 2139 error("%s: cannot get local ipaddr/name", __func__); 2140 goto out; 2141 } 2142 2143 /* XXX sshbuf_put_stringf? */ 2144 xasprintf(&chost, "%s.", lname); 2145 debug2("%s: chost %s", __func__, chost); 2146 2147 /* construct data */ 2148 if ((b = sshbuf_new()) == NULL) { 2149 error("%s: sshbuf_new failed", __func__); 2150 goto out; 2151 } 2152 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2153 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2154 goto out; 2155 } 2156 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2157 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2158 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2159 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2160 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2161 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2162 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2163 (r = sshbuf_put_cstring(b, chost)) != 0 || 2164 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2165 error("%s: buffer error: %s", __func__, ssh_err(r)); 2166 goto out; 2167 } 2168 2169 #ifdef DEBUG_PK 2170 sshbuf_dump(b, stderr); 2171 #endif 2172 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2173 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2174 error("sign using hostkey %s %s failed", 2175 sshkey_ssh_name(private), fp); 2176 goto out; 2177 } 2178 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2179 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2180 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2181 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2182 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2183 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2184 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2185 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2186 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2187 (r = sshpkt_send(ssh)) != 0) { 2188 error("%s: packet error: %s", __func__, ssh_err(r)); 2189 goto out; 2190 } 2191 success = 1; 2192 2193 out: 2194 if (sig != NULL) 2195 freezero(sig, siglen); 2196 free(keyblob); 2197 free(lname); 2198 free(fp); 2199 free(chost); 2200 sshkey_free(private); 2201 sshbuf_free(b); 2202 2203 return success; 2204 } 2205 2206 /* find auth method */ 2207 2208 /* 2209 * given auth method name, if configurable options permit this method fill 2210 * in auth_ident field and return true, otherwise return false. 2211 */ 2212 static int 2213 authmethod_is_enabled(Authmethod *method) 2214 { 2215 if (method == NULL) 2216 return 0; 2217 /* return false if options indicate this method is disabled */ 2218 if (method->enabled == NULL || *method->enabled == 0) 2219 return 0; 2220 /* return false if batch mode is enabled but method needs interactive mode */ 2221 if (method->batch_flag != NULL && *method->batch_flag != 0) 2222 return 0; 2223 return 1; 2224 } 2225 2226 static Authmethod * 2227 authmethod_lookup(const char *name) 2228 { 2229 Authmethod *method = NULL; 2230 if (name != NULL) 2231 for (method = authmethods; method->name != NULL; method++) 2232 if (strcmp(name, method->name) == 0) 2233 return method; 2234 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2235 return NULL; 2236 } 2237 2238 /* XXX internal state */ 2239 static Authmethod *current = NULL; 2240 static char *supported = NULL; 2241 static char *preferred = NULL; 2242 2243 /* 2244 * Given the authentication method list sent by the server, return the 2245 * next method we should try. If the server initially sends a nil list, 2246 * use a built-in default list. 2247 */ 2248 static Authmethod * 2249 authmethod_get(char *authlist) 2250 { 2251 char *name = NULL; 2252 u_int next; 2253 2254 /* Use a suitable default if we're passed a nil list. */ 2255 if (authlist == NULL || strlen(authlist) == 0) 2256 authlist = options.preferred_authentications; 2257 2258 if (supported == NULL || strcmp(authlist, supported) != 0) { 2259 debug3("start over, passed a different list %s", authlist); 2260 free(supported); 2261 supported = xstrdup(authlist); 2262 preferred = options.preferred_authentications; 2263 debug3("preferred %s", preferred); 2264 current = NULL; 2265 } else if (current != NULL && authmethod_is_enabled(current)) 2266 return current; 2267 2268 for (;;) { 2269 if ((name = match_list(preferred, supported, &next)) == NULL) { 2270 debug("No more authentication methods to try."); 2271 current = NULL; 2272 return NULL; 2273 } 2274 preferred += next; 2275 debug3("authmethod_lookup %s", name); 2276 debug3("remaining preferred: %s", preferred); 2277 if ((current = authmethod_lookup(name)) != NULL && 2278 authmethod_is_enabled(current)) { 2279 debug3("authmethod_is_enabled %s", name); 2280 debug("Next authentication method: %s", name); 2281 free(name); 2282 return current; 2283 } 2284 free(name); 2285 } 2286 } 2287 2288 static char * 2289 authmethods_get(void) 2290 { 2291 Authmethod *method = NULL; 2292 struct sshbuf *b; 2293 char *list; 2294 int r; 2295 2296 if ((b = sshbuf_new()) == NULL) 2297 fatal("%s: sshbuf_new failed", __func__); 2298 for (method = authmethods; method->name != NULL; method++) { 2299 if (authmethod_is_enabled(method)) { 2300 if ((r = sshbuf_putf(b, "%s%s", 2301 sshbuf_len(b) ? "," : "", method->name)) != 0) 2302 fatal("%s: buffer error: %s", 2303 __func__, ssh_err(r)); 2304 } 2305 } 2306 if ((list = sshbuf_dup_string(b)) == NULL) 2307 fatal("%s: sshbuf_dup_string failed", __func__); 2308 sshbuf_free(b); 2309 return list; 2310 } 2311