1 /* $OpenBSD: sshconnect2.c,v 1.321 2020/04/17 03:38:47 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <netdb.h> 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdio.h> 40 #include <string.h> 41 #include <stdarg.h> 42 #include <unistd.h> 43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 44 #include <vis.h> 45 #endif 46 47 #include "openbsd-compat/sys-queue.h" 48 49 #include "xmalloc.h" 50 #include "ssh.h" 51 #include "ssh2.h" 52 #include "sshbuf.h" 53 #include "packet.h" 54 #include "compat.h" 55 #include "cipher.h" 56 #include "sshkey.h" 57 #include "kex.h" 58 #include "myproposal.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 #include "ssh-sk.h" 76 #include "sk-api.h" 77 78 #ifdef GSSAPI 79 #include "ssh-gss.h" 80 #endif 81 82 /* import */ 83 extern char *client_version_string; 84 extern char *server_version_string; 85 extern Options options; 86 87 /* 88 * SSH2 key exchange 89 */ 90 91 u_char *session_id2 = NULL; 92 u_int session_id2_len = 0; 93 94 char *xxx_host; 95 struct sockaddr *xxx_hostaddr; 96 97 static int 98 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 99 { 100 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 101 fatal("Host key verification failed."); 102 return 0; 103 } 104 105 static char * 106 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 107 { 108 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 109 size_t maxlen; 110 struct hostkeys *hostkeys; 111 int ktype; 112 u_int i; 113 114 /* Find all hostkeys for this hostname */ 115 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 116 hostkeys = init_hostkeys(); 117 for (i = 0; i < options.num_user_hostfiles; i++) 118 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 119 for (i = 0; i < options.num_system_hostfiles; i++) 120 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 121 122 oavail = avail = xstrdup(options.hostkeyalgorithms); 123 maxlen = strlen(avail) + 1; 124 first = xmalloc(maxlen); 125 last = xmalloc(maxlen); 126 *first = *last = '\0'; 127 128 #define ALG_APPEND(to, from) \ 129 do { \ 130 if (*to != '\0') \ 131 strlcat(to, ",", maxlen); \ 132 strlcat(to, from, maxlen); \ 133 } while (0) 134 135 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 136 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 137 fatal("%s: unknown alg %s", __func__, alg); 138 if (lookup_key_in_hostkeys_by_type(hostkeys, 139 sshkey_type_plain(ktype), NULL)) 140 ALG_APPEND(first, alg); 141 else 142 ALG_APPEND(last, alg); 143 } 144 #undef ALG_APPEND 145 xasprintf(&ret, "%s%s%s", first, 146 (*first == '\0' || *last == '\0') ? "" : ",", last); 147 if (*first != '\0') 148 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 149 150 free(first); 151 free(last); 152 free(hostname); 153 free(oavail); 154 free_hostkeys(hostkeys); 155 156 return ret; 157 } 158 159 void 160 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 161 { 162 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 163 char *s, *all_key; 164 int r, use_known_hosts_order = 0; 165 166 xxx_host = host; 167 xxx_hostaddr = hostaddr; 168 169 /* 170 * If the user has not specified HostkeyAlgorithms, or has only 171 * appended or removed algorithms from that list then prefer algorithms 172 * that are in the list that are supported by known_hosts keys. 173 */ 174 if (options.hostkeyalgorithms == NULL || 175 options.hostkeyalgorithms[0] == '-' || 176 options.hostkeyalgorithms[0] == '+') 177 use_known_hosts_order = 1; 178 179 /* Expand or fill in HostkeyAlgorithms */ 180 all_key = sshkey_alg_list(0, 0, 1, ','); 181 if (kex_assemble_names(&options.hostkeyalgorithms, 182 kex_default_pk_alg(), all_key) != 0) 183 fatal("%s: kex_assemble_namelist", __func__); 184 free(all_key); 185 186 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 187 fatal("%s: kex_names_cat", __func__); 188 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 189 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 190 compat_cipher_proposal(options.ciphers); 191 myproposal[PROPOSAL_ENC_ALGS_STOC] = 192 compat_cipher_proposal(options.ciphers); 193 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 194 myproposal[PROPOSAL_COMP_ALGS_STOC] = 195 (char *)compression_alg_list(options.compression); 196 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 197 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 198 if (use_known_hosts_order) { 199 /* Query known_hosts and prefer algorithms that appear there */ 200 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 201 compat_pkalg_proposal( 202 order_hostkeyalgs(host, hostaddr, port)); 203 } else { 204 /* Use specified HostkeyAlgorithms exactly */ 205 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 206 compat_pkalg_proposal(options.hostkeyalgorithms); 207 } 208 209 if (options.rekey_limit || options.rekey_interval) 210 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 211 options.rekey_interval); 212 213 /* start key exchange */ 214 if ((r = kex_setup(ssh, myproposal)) != 0) 215 fatal("kex_setup: %s", ssh_err(r)); 216 #ifdef WITH_OPENSSL 217 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 218 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 219 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 220 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 221 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 222 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 223 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 224 # ifdef OPENSSL_HAS_ECC 225 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 226 # endif 227 #endif 228 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 229 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 230 ssh->kex->verify_host_key=&verify_host_key_callback; 231 232 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 233 234 /* remove ext-info from the KEX proposals for rekeying */ 235 myproposal[PROPOSAL_KEX_ALGS] = 236 compat_kex_proposal(options.kex_algorithms); 237 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 238 fatal("kex_prop2buf: %s", ssh_err(r)); 239 240 session_id2 = ssh->kex->session_id; 241 session_id2_len = ssh->kex->session_id_len; 242 243 #ifdef DEBUG_KEXDH 244 /* send 1st encrypted/maced/compressed message */ 245 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 246 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 247 (r = sshpkt_send(ssh)) != 0 || 248 (r = ssh_packet_write_wait(ssh)) != 0) 249 fatal("%s: %s", __func__, ssh_err(r)); 250 #endif 251 } 252 253 /* 254 * Authenticate user 255 */ 256 257 typedef struct cauthctxt Authctxt; 258 typedef struct cauthmethod Authmethod; 259 typedef struct identity Identity; 260 typedef struct idlist Idlist; 261 262 struct identity { 263 TAILQ_ENTRY(identity) next; 264 int agent_fd; /* >=0 if agent supports key */ 265 struct sshkey *key; /* public/private key */ 266 char *filename; /* comment for agent-only keys */ 267 int tried; 268 int isprivate; /* key points to the private key */ 269 int userprovided; 270 }; 271 TAILQ_HEAD(idlist, identity); 272 273 struct cauthctxt { 274 const char *server_user; 275 const char *local_user; 276 const char *host; 277 const char *service; 278 struct cauthmethod *method; 279 sig_atomic_t success; 280 char *authlist; 281 #ifdef GSSAPI 282 /* gssapi */ 283 gss_OID_set gss_supported_mechs; 284 u_int mech_tried; 285 #endif 286 /* pubkey */ 287 struct idlist keys; 288 int agent_fd; 289 /* hostbased */ 290 Sensitive *sensitive; 291 char *oktypes, *ktypes; 292 const char *active_ktype; 293 /* kbd-interactive */ 294 int info_req_seen; 295 int attempt_kbdint; 296 /* password */ 297 int attempt_passwd; 298 /* generic */ 299 void *methoddata; 300 }; 301 302 struct cauthmethod { 303 char *name; /* string to compare against server's list */ 304 int (*userauth)(struct ssh *ssh); 305 void (*cleanup)(struct ssh *ssh); 306 int *enabled; /* flag in option struct that enables method */ 307 int *batch_flag; /* flag in option struct that disables method */ 308 }; 309 310 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 311 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 312 static int input_userauth_success(int, u_int32_t, struct ssh *); 313 static int input_userauth_failure(int, u_int32_t, struct ssh *); 314 static int input_userauth_banner(int, u_int32_t, struct ssh *); 315 static int input_userauth_error(int, u_int32_t, struct ssh *); 316 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 317 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 318 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 319 320 static int userauth_none(struct ssh *); 321 static int userauth_pubkey(struct ssh *); 322 static int userauth_passwd(struct ssh *); 323 static int userauth_kbdint(struct ssh *); 324 static int userauth_hostbased(struct ssh *); 325 326 #ifdef GSSAPI 327 static int userauth_gssapi(struct ssh *); 328 static void userauth_gssapi_cleanup(struct ssh *); 329 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 330 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 331 static int input_gssapi_error(int, u_int32_t, struct ssh *); 332 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 333 #endif 334 335 void userauth(struct ssh *, char *); 336 337 static void pubkey_cleanup(struct ssh *); 338 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 339 static void pubkey_prepare(Authctxt *); 340 static void pubkey_reset(Authctxt *); 341 static struct sshkey *load_identity_file(Identity *); 342 343 static Authmethod *authmethod_get(char *authlist); 344 static Authmethod *authmethod_lookup(const char *name); 345 static char *authmethods_get(void); 346 347 Authmethod authmethods[] = { 348 #ifdef GSSAPI 349 {"gssapi-with-mic", 350 userauth_gssapi, 351 userauth_gssapi_cleanup, 352 &options.gss_authentication, 353 NULL}, 354 #endif 355 {"hostbased", 356 userauth_hostbased, 357 NULL, 358 &options.hostbased_authentication, 359 NULL}, 360 {"publickey", 361 userauth_pubkey, 362 NULL, 363 &options.pubkey_authentication, 364 NULL}, 365 {"keyboard-interactive", 366 userauth_kbdint, 367 NULL, 368 &options.kbd_interactive_authentication, 369 &options.batch_mode}, 370 {"password", 371 userauth_passwd, 372 NULL, 373 &options.password_authentication, 374 &options.batch_mode}, 375 {"none", 376 userauth_none, 377 NULL, 378 NULL, 379 NULL}, 380 {NULL, NULL, NULL, NULL, NULL} 381 }; 382 383 void 384 ssh_userauth2(struct ssh *ssh, const char *local_user, 385 const char *server_user, char *host, Sensitive *sensitive) 386 { 387 Authctxt authctxt; 388 int r; 389 390 if (options.challenge_response_authentication) 391 options.kbd_interactive_authentication = 1; 392 if (options.preferred_authentications == NULL) 393 options.preferred_authentications = authmethods_get(); 394 395 /* setup authentication context */ 396 memset(&authctxt, 0, sizeof(authctxt)); 397 authctxt.server_user = server_user; 398 authctxt.local_user = local_user; 399 authctxt.host = host; 400 authctxt.service = "ssh-connection"; /* service name */ 401 authctxt.success = 0; 402 authctxt.method = authmethod_lookup("none"); 403 authctxt.authlist = NULL; 404 authctxt.methoddata = NULL; 405 authctxt.sensitive = sensitive; 406 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 407 authctxt.info_req_seen = 0; 408 authctxt.attempt_kbdint = 0; 409 authctxt.attempt_passwd = 0; 410 #if GSSAPI 411 authctxt.gss_supported_mechs = NULL; 412 authctxt.mech_tried = 0; 413 #endif 414 authctxt.agent_fd = -1; 415 pubkey_prepare(&authctxt); 416 if (authctxt.method == NULL) { 417 fatal("%s: internal error: cannot send userauth none request", 418 __func__); 419 } 420 421 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 422 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 423 (r = sshpkt_send(ssh)) != 0) 424 fatal("%s: %s", __func__, ssh_err(r)); 425 426 ssh->authctxt = &authctxt; 427 ssh_dispatch_init(ssh, &input_userauth_error); 428 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 429 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 430 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 431 pubkey_cleanup(ssh); 432 ssh->authctxt = NULL; 433 434 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 435 436 if (!authctxt.success) 437 fatal("Authentication failed."); 438 debug("Authentication succeeded (%s).", authctxt.method->name); 439 } 440 441 /* ARGSUSED */ 442 static int 443 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 444 { 445 int r; 446 447 if (ssh_packet_remaining(ssh) > 0) { 448 char *reply; 449 450 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 451 goto out; 452 debug2("service_accept: %s", reply); 453 free(reply); 454 } else { 455 debug2("buggy server: service_accept w/o service"); 456 } 457 if ((r = sshpkt_get_end(ssh)) != 0) 458 goto out; 459 debug("SSH2_MSG_SERVICE_ACCEPT received"); 460 461 /* initial userauth request */ 462 userauth_none(ssh); 463 464 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 465 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 466 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 467 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 468 r = 0; 469 out: 470 return r; 471 } 472 473 /* ARGSUSED */ 474 static int 475 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 476 { 477 return kex_input_ext_info(type, seqnr, ssh); 478 } 479 480 void 481 userauth(struct ssh *ssh, char *authlist) 482 { 483 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 484 485 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 486 authctxt->method->cleanup(ssh); 487 488 free(authctxt->methoddata); 489 authctxt->methoddata = NULL; 490 if (authlist == NULL) { 491 authlist = authctxt->authlist; 492 } else { 493 free(authctxt->authlist); 494 authctxt->authlist = authlist; 495 } 496 for (;;) { 497 Authmethod *method = authmethod_get(authlist); 498 if (method == NULL) 499 fatal("%s@%s: Permission denied (%s).", 500 authctxt->server_user, authctxt->host, authlist); 501 authctxt->method = method; 502 503 /* reset the per method handler */ 504 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 505 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 506 507 /* and try new method */ 508 if (method->userauth(ssh) != 0) { 509 debug2("we sent a %s packet, wait for reply", method->name); 510 break; 511 } else { 512 debug2("we did not send a packet, disable method"); 513 method->enabled = NULL; 514 } 515 } 516 } 517 518 /* ARGSUSED */ 519 static int 520 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 521 { 522 fatal("%s: bad message during authentication: type %d", __func__, type); 523 return 0; 524 } 525 526 /* ARGSUSED */ 527 static int 528 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 529 { 530 char *msg = NULL; 531 size_t len; 532 int r; 533 534 debug3("%s", __func__); 535 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 536 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 537 goto out; 538 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 539 fmprintf(stderr, "%s", msg); 540 r = 0; 541 out: 542 free(msg); 543 return r; 544 } 545 546 /* ARGSUSED */ 547 static int 548 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 549 { 550 Authctxt *authctxt = ssh->authctxt; 551 552 if (authctxt == NULL) 553 fatal("%s: no authentication context", __func__); 554 free(authctxt->authlist); 555 authctxt->authlist = NULL; 556 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 557 authctxt->method->cleanup(ssh); 558 free(authctxt->methoddata); 559 authctxt->methoddata = NULL; 560 authctxt->success = 1; /* break out */ 561 return 0; 562 } 563 564 #if 0 565 static int 566 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 567 { 568 Authctxt *authctxt = ssh->authctxt; 569 570 if (authctxt == NULL) 571 fatal("%s: no authentication context", __func__); 572 573 fatal("Unexpected authentication success during %s.", 574 authctxt->method->name); 575 return 0; 576 } 577 #endif 578 579 /* ARGSUSED */ 580 static int 581 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 582 { 583 Authctxt *authctxt = ssh->authctxt; 584 char *authlist = NULL; 585 u_char partial; 586 587 if (authctxt == NULL) 588 fatal("input_userauth_failure: no authentication context"); 589 590 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 591 sshpkt_get_u8(ssh, &partial) != 0 || 592 sshpkt_get_end(ssh) != 0) 593 goto out; 594 595 if (partial != 0) { 596 verbose("Authenticated with partial success."); 597 /* reset state */ 598 pubkey_reset(authctxt); 599 } 600 debug("Authentications that can continue: %s", authlist); 601 602 userauth(ssh, authlist); 603 authlist = NULL; 604 out: 605 free(authlist); 606 return 0; 607 } 608 609 /* 610 * Format an identity for logging including filename, key type, fingerprint 611 * and location (agent, etc.). Caller must free. 612 */ 613 static char * 614 format_identity(Identity *id) 615 { 616 char *fp = NULL, *ret = NULL; 617 const char *note = ""; 618 619 if (id->key != NULL) { 620 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 621 SSH_FP_DEFAULT); 622 } 623 if (id->key) { 624 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 625 note = " token"; 626 else if (sshkey_is_sk(id->key)) 627 note = " authenticator"; 628 } 629 xasprintf(&ret, "%s %s%s%s%s%s%s", 630 id->filename, 631 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 632 fp ? fp : "", 633 id->userprovided ? " explicit" : "", note, 634 id->agent_fd != -1 ? " agent" : ""); 635 free(fp); 636 return ret; 637 } 638 639 /* ARGSUSED */ 640 static int 641 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 642 { 643 Authctxt *authctxt = ssh->authctxt; 644 struct sshkey *key = NULL; 645 Identity *id = NULL; 646 int pktype, found = 0, sent = 0; 647 size_t blen; 648 char *pkalg = NULL, *fp = NULL, *ident = NULL; 649 u_char *pkblob = NULL; 650 int r; 651 652 if (authctxt == NULL) 653 fatal("input_userauth_pk_ok: no authentication context"); 654 655 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 656 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 657 (r = sshpkt_get_end(ssh)) != 0) 658 goto done; 659 660 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 661 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 662 goto done; 663 } 664 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 665 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 666 goto done; 667 } 668 if (key->type != pktype) { 669 error("input_userauth_pk_ok: type mismatch " 670 "for decoded key (received %d, expected %d)", 671 key->type, pktype); 672 goto done; 673 } 674 675 /* 676 * search keys in the reverse order, because last candidate has been 677 * moved to the end of the queue. this also avoids confusion by 678 * duplicate keys 679 */ 680 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 681 if (sshkey_equal(key, id->key)) { 682 found = 1; 683 break; 684 } 685 } 686 if (!found || id == NULL) { 687 fp = sshkey_fingerprint(key, options.fingerprint_hash, 688 SSH_FP_DEFAULT); 689 error("%s: server replied with unknown key: %s %s", __func__, 690 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 691 goto done; 692 } 693 ident = format_identity(id); 694 debug("Server accepts key: %s", ident); 695 sent = sign_and_send_pubkey(ssh, id); 696 r = 0; 697 done: 698 sshkey_free(key); 699 free(ident); 700 free(fp); 701 free(pkalg); 702 free(pkblob); 703 704 /* try another method if we did not send a packet */ 705 if (r == 0 && sent == 0) 706 userauth(ssh, NULL); 707 return r; 708 } 709 710 #ifdef GSSAPI 711 static int 712 userauth_gssapi(struct ssh *ssh) 713 { 714 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 715 Gssctxt *gssctxt = NULL; 716 OM_uint32 min; 717 int r, ok = 0; 718 gss_OID mech = NULL; 719 720 /* Try one GSSAPI method at a time, rather than sending them all at 721 * once. */ 722 723 if (authctxt->gss_supported_mechs == NULL) 724 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 725 726 /* Check to see whether the mechanism is usable before we offer it */ 727 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 728 !ok) { 729 mech = &authctxt->gss_supported_mechs-> 730 elements[authctxt->mech_tried]; 731 /* My DER encoding requires length<128 */ 732 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 733 mech, authctxt->host)) { 734 ok = 1; /* Mechanism works */ 735 } else { 736 authctxt->mech_tried++; 737 } 738 } 739 740 if (!ok || mech == NULL) 741 return 0; 742 743 authctxt->methoddata=(void *)gssctxt; 744 745 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 746 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 747 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 748 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 749 (r = sshpkt_put_u32(ssh, 1)) != 0 || 750 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 751 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 752 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 753 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 754 (r = sshpkt_send(ssh)) != 0) 755 fatal("%s: %s", __func__, ssh_err(r)); 756 757 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 758 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 759 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 760 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 761 762 authctxt->mech_tried++; /* Move along to next candidate */ 763 764 return 1; 765 } 766 767 static void 768 userauth_gssapi_cleanup(struct ssh *ssh) 769 { 770 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 771 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 772 773 ssh_gssapi_delete_ctx(&gssctxt); 774 authctxt->methoddata = NULL; 775 776 free(authctxt->gss_supported_mechs); 777 authctxt->gss_supported_mechs = NULL; 778 } 779 780 static OM_uint32 781 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 782 { 783 Authctxt *authctxt = ssh->authctxt; 784 Gssctxt *gssctxt = authctxt->methoddata; 785 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 786 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 787 gss_buffer_desc gssbuf; 788 OM_uint32 status, ms, flags; 789 int r; 790 791 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 792 recv_tok, &send_tok, &flags); 793 794 if (send_tok.length > 0) { 795 u_char type = GSS_ERROR(status) ? 796 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 797 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 798 799 if ((r = sshpkt_start(ssh, type)) != 0 || 800 (r = sshpkt_put_string(ssh, send_tok.value, 801 send_tok.length)) != 0 || 802 (r = sshpkt_send(ssh)) != 0) 803 fatal("%s: %s", __func__, ssh_err(r)); 804 805 gss_release_buffer(&ms, &send_tok); 806 } 807 808 if (status == GSS_S_COMPLETE) { 809 /* send either complete or MIC, depending on mechanism */ 810 if (!(flags & GSS_C_INTEG_FLAG)) { 811 if ((r = sshpkt_start(ssh, 812 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 813 (r = sshpkt_send(ssh)) != 0) 814 fatal("%s: %s", __func__, ssh_err(r)); 815 } else { 816 struct sshbuf *b; 817 818 if ((b = sshbuf_new()) == NULL) 819 fatal("%s: sshbuf_new failed", __func__); 820 ssh_gssapi_buildmic(b, authctxt->server_user, 821 authctxt->service, "gssapi-with-mic"); 822 823 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 824 fatal("%s: sshbuf_mutable_ptr failed", __func__); 825 gssbuf.length = sshbuf_len(b); 826 827 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 828 829 if (!GSS_ERROR(status)) { 830 if ((r = sshpkt_start(ssh, 831 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 832 (r = sshpkt_put_string(ssh, mic.value, 833 mic.length)) != 0 || 834 (r = sshpkt_send(ssh)) != 0) 835 fatal("%s: %s", __func__, ssh_err(r)); 836 } 837 838 sshbuf_free(b); 839 gss_release_buffer(&ms, &mic); 840 } 841 } 842 843 return status; 844 } 845 846 /* ARGSUSED */ 847 static int 848 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 849 { 850 Authctxt *authctxt = ssh->authctxt; 851 Gssctxt *gssctxt; 852 size_t oidlen; 853 u_char *oidv = NULL; 854 int r; 855 856 if (authctxt == NULL) 857 fatal("input_gssapi_response: no authentication context"); 858 gssctxt = authctxt->methoddata; 859 860 /* Setup our OID */ 861 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 862 goto done; 863 864 if (oidlen <= 2 || 865 oidv[0] != SSH_GSS_OIDTYPE || 866 oidv[1] != oidlen - 2) { 867 debug("Badly encoded mechanism OID received"); 868 userauth(ssh, NULL); 869 goto ok; 870 } 871 872 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 873 fatal("Server returned different OID than expected"); 874 875 if ((r = sshpkt_get_end(ssh)) != 0) 876 goto done; 877 878 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 879 /* Start again with next method on list */ 880 debug("Trying to start again"); 881 userauth(ssh, NULL); 882 goto ok; 883 } 884 ok: 885 r = 0; 886 done: 887 free(oidv); 888 return r; 889 } 890 891 /* ARGSUSED */ 892 static int 893 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 894 { 895 Authctxt *authctxt = ssh->authctxt; 896 gss_buffer_desc recv_tok; 897 u_char *p = NULL; 898 size_t len; 899 OM_uint32 status; 900 int r; 901 902 if (authctxt == NULL) 903 fatal("input_gssapi_response: no authentication context"); 904 905 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 906 (r = sshpkt_get_end(ssh)) != 0) 907 goto out; 908 909 recv_tok.value = p; 910 recv_tok.length = len; 911 status = process_gssapi_token(ssh, &recv_tok); 912 913 /* Start again with the next method in the list */ 914 if (GSS_ERROR(status)) { 915 userauth(ssh, NULL); 916 /* ok */ 917 } 918 r = 0; 919 out: 920 free(p); 921 return r; 922 } 923 924 /* ARGSUSED */ 925 static int 926 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 927 { 928 Authctxt *authctxt = ssh->authctxt; 929 Gssctxt *gssctxt; 930 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 931 gss_buffer_desc recv_tok; 932 OM_uint32 ms; 933 u_char *p = NULL; 934 size_t len; 935 int r; 936 937 if (authctxt == NULL) 938 fatal("input_gssapi_response: no authentication context"); 939 gssctxt = authctxt->methoddata; 940 941 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 942 (r = sshpkt_get_end(ssh)) != 0) { 943 free(p); 944 return r; 945 } 946 947 /* Stick it into GSSAPI and see what it says */ 948 recv_tok.value = p; 949 recv_tok.length = len; 950 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 951 &recv_tok, &send_tok, NULL); 952 free(p); 953 gss_release_buffer(&ms, &send_tok); 954 955 /* Server will be returning a failed packet after this one */ 956 return 0; 957 } 958 959 /* ARGSUSED */ 960 static int 961 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 962 { 963 char *msg = NULL; 964 char *lang = NULL; 965 int r; 966 967 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 968 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 969 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 970 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 971 goto out; 972 r = sshpkt_get_end(ssh); 973 debug("Server GSSAPI Error:\n%s", msg); 974 out: 975 free(msg); 976 free(lang); 977 return r; 978 } 979 #endif /* GSSAPI */ 980 981 static int 982 userauth_none(struct ssh *ssh) 983 { 984 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 985 int r; 986 987 /* initial userauth request */ 988 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 989 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 990 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 991 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 992 (r = sshpkt_send(ssh)) != 0) 993 fatal("%s: %s", __func__, ssh_err(r)); 994 return 1; 995 } 996 997 static int 998 userauth_passwd(struct ssh *ssh) 999 { 1000 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1001 char *password, *prompt = NULL; 1002 const char *host = options.host_key_alias ? options.host_key_alias : 1003 authctxt->host; 1004 int r; 1005 1006 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1007 return 0; 1008 1009 if (authctxt->attempt_passwd != 1) 1010 error("Permission denied, please try again."); 1011 1012 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1013 password = read_passphrase(prompt, 0); 1014 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1015 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1016 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1017 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1018 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1019 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1020 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1021 (r = sshpkt_send(ssh)) != 0) 1022 fatal("%s: %s", __func__, ssh_err(r)); 1023 1024 free(prompt); 1025 if (password != NULL) 1026 freezero(password, strlen(password)); 1027 1028 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1029 &input_userauth_passwd_changereq); 1030 1031 return 1; 1032 } 1033 1034 /* 1035 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1036 */ 1037 /* ARGSUSED */ 1038 static int 1039 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1040 { 1041 Authctxt *authctxt = ssh->authctxt; 1042 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1043 char prompt[256]; 1044 const char *host; 1045 int r; 1046 1047 debug2("input_userauth_passwd_changereq"); 1048 1049 if (authctxt == NULL) 1050 fatal("input_userauth_passwd_changereq: " 1051 "no authentication context"); 1052 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1053 1054 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1055 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1056 goto out; 1057 if (strlen(info) > 0) 1058 logit("%s", info); 1059 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1060 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1061 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1062 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1063 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1064 goto out; 1065 1066 snprintf(prompt, sizeof(prompt), 1067 "Enter %.30s@%.128s's old password: ", 1068 authctxt->server_user, host); 1069 password = read_passphrase(prompt, 0); 1070 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1071 goto out; 1072 1073 freezero(password, strlen(password)); 1074 password = NULL; 1075 while (password == NULL) { 1076 snprintf(prompt, sizeof(prompt), 1077 "Enter %.30s@%.128s's new password: ", 1078 authctxt->server_user, host); 1079 password = read_passphrase(prompt, RP_ALLOW_EOF); 1080 if (password == NULL) { 1081 /* bail out */ 1082 r = 0; 1083 goto out; 1084 } 1085 snprintf(prompt, sizeof(prompt), 1086 "Retype %.30s@%.128s's new password: ", 1087 authctxt->server_user, host); 1088 retype = read_passphrase(prompt, 0); 1089 if (strcmp(password, retype) != 0) { 1090 freezero(password, strlen(password)); 1091 logit("Mismatch; try again, EOF to quit."); 1092 password = NULL; 1093 } 1094 freezero(retype, strlen(retype)); 1095 } 1096 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1097 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1098 (r = sshpkt_send(ssh)) != 0) 1099 goto out; 1100 1101 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1102 &input_userauth_passwd_changereq); 1103 r = 0; 1104 out: 1105 if (password) 1106 freezero(password, strlen(password)); 1107 free(info); 1108 free(lang); 1109 return r; 1110 } 1111 1112 /* 1113 * Select an algorithm for publickey signatures. 1114 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1115 * 1116 * Call with ssh==NULL to ignore server-sig-algs extension list and 1117 * only attempt with the key's base signature type. 1118 */ 1119 static char * 1120 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1121 { 1122 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1123 1124 /* 1125 * The signature algorithm will only differ from the key algorithm 1126 * for RSA keys/certs and when the server advertises support for 1127 * newer (SHA2) algorithms. 1128 */ 1129 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1130 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1131 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1132 /* Filter base key signature alg against our configuration */ 1133 return match_list(sshkey_ssh_name(key), 1134 options.pubkey_key_types, NULL); 1135 } 1136 1137 /* 1138 * For RSA keys/certs, since these might have a different sig type: 1139 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1140 * that also appears in the supported signature algorithms list from 1141 * the server. 1142 */ 1143 oallowed = allowed = xstrdup(options.pubkey_key_types); 1144 while ((cp = strsep(&allowed, ",")) != NULL) { 1145 if (sshkey_type_from_name(cp) != key->type) 1146 continue; 1147 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1148 if (tmp != NULL) 1149 alg = xstrdup(cp); 1150 free(tmp); 1151 if (alg != NULL) 1152 break; 1153 } 1154 free(oallowed); 1155 return alg; 1156 } 1157 1158 static int 1159 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1160 const u_char *data, size_t datalen, u_int compat, const char *alg) 1161 { 1162 struct sshkey *sign_key = NULL, *prv = NULL; 1163 int r = SSH_ERR_INTERNAL_ERROR; 1164 struct notifier_ctx *notifier = NULL; 1165 char *fp = NULL; 1166 1167 *sigp = NULL; 1168 *lenp = 0; 1169 1170 /* The agent supports this key. */ 1171 if (id->key != NULL && id->agent_fd != -1) { 1172 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1173 data, datalen, alg, compat); 1174 } 1175 1176 /* 1177 * We have already loaded the private key or the private key is 1178 * stored in external hardware. 1179 */ 1180 if (id->key != NULL && 1181 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1182 sign_key = id->key; 1183 } else { 1184 /* Load the private key from the file. */ 1185 if ((prv = load_identity_file(id)) == NULL) 1186 return SSH_ERR_KEY_NOT_FOUND; 1187 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1188 error("%s: private key %s contents do not match public", 1189 __func__, id->filename); 1190 r = SSH_ERR_KEY_NOT_FOUND; 1191 goto out; 1192 } 1193 sign_key = prv; 1194 if (sshkey_is_sk(sign_key) && 1195 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1196 /* XXX match batch mode should just skip these keys? */ 1197 if ((fp = sshkey_fingerprint(sign_key, 1198 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1199 fatal("%s: sshkey_fingerprint", __func__); 1200 notifier = notify_start(options.batch_mode, 1201 "Confirm user presence for key %s %s", 1202 sshkey_type(sign_key), fp); 1203 free(fp); 1204 } 1205 } 1206 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1207 alg, options.sk_provider, compat)) != 0) { 1208 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1209 goto out; 1210 } 1211 /* 1212 * PKCS#11 tokens may not support all signature algorithms, 1213 * so check what we get back. 1214 */ 1215 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1216 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1217 goto out; 1218 } 1219 /* success */ 1220 r = 0; 1221 out: 1222 notify_complete(notifier); 1223 sshkey_free(prv); 1224 return r; 1225 } 1226 1227 static int 1228 id_filename_matches(Identity *id, Identity *private_id) 1229 { 1230 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1231 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1232 size_t i, slen; 1233 1234 if (strcmp(id->filename, private_id->filename) == 0) 1235 return 1; 1236 for (i = 0; suffixes[i]; i++) { 1237 slen = strlen(suffixes[i]); 1238 if (len > slen && plen == len - slen && 1239 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1240 memcmp(id->filename, private_id->filename, plen) == 0) 1241 return 1; 1242 } 1243 return 0; 1244 } 1245 1246 static int 1247 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1248 { 1249 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1250 struct sshbuf *b = NULL; 1251 Identity *private_id, *sign_id = NULL; 1252 u_char *signature = NULL; 1253 size_t slen = 0, skip = 0; 1254 int r, fallback_sigtype, sent = 0; 1255 char *alg = NULL, *fp = NULL; 1256 const char *loc = ""; 1257 1258 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1259 SSH_FP_DEFAULT)) == NULL) 1260 return 0; 1261 1262 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1263 1264 /* 1265 * If the key is an certificate, try to find a matching private key 1266 * and use it to complete the signature. 1267 * If no such private key exists, fall back to trying the certificate 1268 * key itself in case it has a private half already loaded. 1269 * This will try to set sign_id to the private key that will perform 1270 * the signature. 1271 */ 1272 if (sshkey_is_cert(id->key)) { 1273 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1274 if (sshkey_equal_public(id->key, private_id->key) && 1275 id->key->type != private_id->key->type) { 1276 sign_id = private_id; 1277 break; 1278 } 1279 } 1280 /* 1281 * Exact key matches are preferred, but also allow 1282 * filename matches for non-PKCS#11/agent keys that 1283 * didn't load public keys. This supports the case 1284 * of keeping just a private key file and public 1285 * certificate on disk. 1286 */ 1287 if (sign_id == NULL && 1288 !id->isprivate && id->agent_fd == -1 && 1289 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1290 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1291 if (private_id->key == NULL && 1292 id_filename_matches(id, private_id)) { 1293 sign_id = private_id; 1294 break; 1295 } 1296 } 1297 } 1298 if (sign_id != NULL) { 1299 debug2("%s: using private key \"%s\"%s for " 1300 "certificate", __func__, id->filename, 1301 id->agent_fd != -1 ? " from agent" : ""); 1302 } else { 1303 debug("%s: no separate private key for certificate " 1304 "\"%s\"", __func__, id->filename); 1305 } 1306 } 1307 1308 /* 1309 * If the above didn't select another identity to do the signing 1310 * then default to the one we started with. 1311 */ 1312 if (sign_id == NULL) 1313 sign_id = id; 1314 1315 /* assemble and sign data */ 1316 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1317 free(alg); 1318 slen = 0; 1319 signature = NULL; 1320 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1321 id->key)) == NULL) { 1322 error("%s: no mutual signature supported", __func__); 1323 goto out; 1324 } 1325 debug3("%s: signing using %s %s", __func__, alg, fp); 1326 1327 sshbuf_free(b); 1328 if ((b = sshbuf_new()) == NULL) 1329 fatal("%s: sshbuf_new failed", __func__); 1330 if (datafellows & SSH_OLD_SESSIONID) { 1331 if ((r = sshbuf_put(b, session_id2, 1332 session_id2_len)) != 0) { 1333 fatal("%s: sshbuf_put: %s", 1334 __func__, ssh_err(r)); 1335 } 1336 } else { 1337 if ((r = sshbuf_put_string(b, session_id2, 1338 session_id2_len)) != 0) { 1339 fatal("%s: sshbuf_put_string: %s", 1340 __func__, ssh_err(r)); 1341 } 1342 } 1343 skip = sshbuf_len(b); 1344 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1345 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1346 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1347 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1348 (r = sshbuf_put_u8(b, 1)) != 0 || 1349 (r = sshbuf_put_cstring(b, alg)) != 0 || 1350 (r = sshkey_puts(id->key, b)) != 0) { 1351 fatal("%s: assemble signed data: %s", 1352 __func__, ssh_err(r)); 1353 } 1354 1355 /* generate signature */ 1356 r = identity_sign(sign_id, &signature, &slen, 1357 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1358 if (r == 0) 1359 break; 1360 else if (r == SSH_ERR_KEY_NOT_FOUND) 1361 goto out; /* soft failure */ 1362 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1363 !fallback_sigtype) { 1364 if (sign_id->agent_fd != -1) 1365 loc = "agent "; 1366 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1367 loc = "token "; 1368 logit("%skey %s %s returned incorrect signature type", 1369 loc, sshkey_type(id->key), fp); 1370 continue; 1371 } 1372 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1373 sshkey_type(sign_id->key), sign_id->filename, 1374 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1375 goto out; 1376 } 1377 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1378 fatal("%s: no signature", __func__); 1379 1380 /* append signature */ 1381 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1382 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1383 1384 #ifdef DEBUG_PK 1385 sshbuf_dump(b, stderr); 1386 #endif 1387 /* skip session id and packet type */ 1388 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1389 fatal("%s: consume: %s", __func__, ssh_err(r)); 1390 1391 /* put remaining data from buffer into packet */ 1392 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1393 (r = sshpkt_putb(ssh, b)) != 0 || 1394 (r = sshpkt_send(ssh)) != 0) 1395 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1396 1397 /* success */ 1398 sent = 1; 1399 1400 out: 1401 free(fp); 1402 free(alg); 1403 sshbuf_free(b); 1404 freezero(signature, slen); 1405 return sent; 1406 } 1407 1408 static int 1409 send_pubkey_test(struct ssh *ssh, Identity *id) 1410 { 1411 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1412 u_char *blob = NULL; 1413 char *alg = NULL; 1414 size_t bloblen; 1415 u_int have_sig = 0; 1416 int sent = 0, r; 1417 1418 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1419 debug("%s: no mutual signature algorithm", __func__); 1420 goto out; 1421 } 1422 1423 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1424 /* we cannot handle this key */ 1425 debug3("%s: cannot handle key", __func__); 1426 goto out; 1427 } 1428 /* register callback for USERAUTH_PK_OK message */ 1429 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1430 1431 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1432 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1433 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1434 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1435 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1436 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1437 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1438 (r = sshpkt_send(ssh)) != 0) 1439 fatal("%s: %s", __func__, ssh_err(r)); 1440 sent = 1; 1441 1442 out: 1443 free(alg); 1444 free(blob); 1445 return sent; 1446 } 1447 1448 static struct sshkey * 1449 load_identity_file(Identity *id) 1450 { 1451 struct sshkey *private = NULL; 1452 char prompt[300], *passphrase, *comment; 1453 int r, quit = 0, i; 1454 struct stat st; 1455 1456 if (stat(id->filename, &st) == -1) { 1457 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1458 id->filename, strerror(errno)); 1459 return NULL; 1460 } 1461 snprintf(prompt, sizeof prompt, 1462 "Enter passphrase for key '%.100s': ", id->filename); 1463 for (i = 0; i <= options.number_of_password_prompts; i++) { 1464 if (i == 0) 1465 passphrase = ""; 1466 else { 1467 passphrase = read_passphrase(prompt, 0); 1468 if (*passphrase == '\0') { 1469 debug2("no passphrase given, try next key"); 1470 free(passphrase); 1471 break; 1472 } 1473 } 1474 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1475 passphrase, &private, &comment))) { 1476 case 0: 1477 break; 1478 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1479 if (options.batch_mode) { 1480 quit = 1; 1481 break; 1482 } 1483 if (i != 0) 1484 debug2("bad passphrase given, try again..."); 1485 break; 1486 case SSH_ERR_SYSTEM_ERROR: 1487 if (errno == ENOENT) { 1488 debug2("Load key \"%s\": %s", 1489 id->filename, ssh_err(r)); 1490 quit = 1; 1491 break; 1492 } 1493 /* FALLTHROUGH */ 1494 default: 1495 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1496 quit = 1; 1497 break; 1498 } 1499 if (private != NULL && sshkey_is_sk(private) && 1500 options.sk_provider == NULL) { 1501 debug("key \"%s\" is an authenticator-hosted key, " 1502 "but no provider specified", id->filename); 1503 sshkey_free(private); 1504 private = NULL; 1505 quit = 1; 1506 } 1507 if (!quit && private != NULL && id->agent_fd == -1 && 1508 !(id->key && id->isprivate)) 1509 maybe_add_key_to_agent(id->filename, private, comment, 1510 passphrase); 1511 if (i > 0) 1512 freezero(passphrase, strlen(passphrase)); 1513 free(comment); 1514 if (private != NULL || quit) 1515 break; 1516 } 1517 return private; 1518 } 1519 1520 static int 1521 key_type_allowed_by_config(struct sshkey *key) 1522 { 1523 if (match_pattern_list(sshkey_ssh_name(key), 1524 options.pubkey_key_types, 0) == 1) 1525 return 1; 1526 1527 /* RSA keys/certs might be allowed by alternate signature types */ 1528 switch (key->type) { 1529 case KEY_RSA: 1530 if (match_pattern_list("rsa-sha2-512", 1531 options.pubkey_key_types, 0) == 1) 1532 return 1; 1533 if (match_pattern_list("rsa-sha2-256", 1534 options.pubkey_key_types, 0) == 1) 1535 return 1; 1536 break; 1537 case KEY_RSA_CERT: 1538 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1539 options.pubkey_key_types, 0) == 1) 1540 return 1; 1541 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1542 options.pubkey_key_types, 0) == 1) 1543 return 1; 1544 break; 1545 } 1546 return 0; 1547 } 1548 1549 1550 /* 1551 * try keys in the following order: 1552 * 1. certificates listed in the config file 1553 * 2. other input certificates 1554 * 3. agent keys that are found in the config file 1555 * 4. other agent keys 1556 * 5. keys that are only listed in the config file 1557 */ 1558 static void 1559 pubkey_prepare(Authctxt *authctxt) 1560 { 1561 struct identity *id, *id2, *tmp; 1562 struct idlist agent, files, *preferred; 1563 struct sshkey *key; 1564 int agent_fd = -1, i, r, found; 1565 size_t j; 1566 struct ssh_identitylist *idlist; 1567 char *ident; 1568 1569 TAILQ_INIT(&agent); /* keys from the agent */ 1570 TAILQ_INIT(&files); /* keys from the config file */ 1571 preferred = &authctxt->keys; 1572 TAILQ_INIT(preferred); /* preferred order of keys */ 1573 1574 /* list of keys stored in the filesystem and PKCS#11 */ 1575 for (i = 0; i < options.num_identity_files; i++) { 1576 key = options.identity_keys[i]; 1577 if (key && key->cert && 1578 key->cert->type != SSH2_CERT_TYPE_USER) { 1579 debug("%s: ignoring certificate %s: not a user " 1580 "certificate", __func__, 1581 options.identity_files[i]); 1582 continue; 1583 } 1584 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1585 debug("%s: ignoring authenticator-hosted key %s as no " 1586 "SecurityKeyProvider has been specified", 1587 __func__, options.identity_files[i]); 1588 continue; 1589 } 1590 options.identity_keys[i] = NULL; 1591 id = xcalloc(1, sizeof(*id)); 1592 id->agent_fd = -1; 1593 id->key = key; 1594 id->filename = xstrdup(options.identity_files[i]); 1595 id->userprovided = options.identity_file_userprovided[i]; 1596 TAILQ_INSERT_TAIL(&files, id, next); 1597 } 1598 /* list of certificates specified by user */ 1599 for (i = 0; i < options.num_certificate_files; i++) { 1600 key = options.certificates[i]; 1601 if (!sshkey_is_cert(key) || key->cert == NULL || 1602 key->cert->type != SSH2_CERT_TYPE_USER) { 1603 debug("%s: ignoring certificate %s: not a user " 1604 "certificate", __func__, 1605 options.identity_files[i]); 1606 continue; 1607 } 1608 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1609 debug("%s: ignoring authenticator-hosted key " 1610 "certificate %s as no " 1611 "SecurityKeyProvider has been specified", 1612 __func__, options.identity_files[i]); 1613 continue; 1614 } 1615 id = xcalloc(1, sizeof(*id)); 1616 id->agent_fd = -1; 1617 id->key = key; 1618 id->filename = xstrdup(options.certificate_files[i]); 1619 id->userprovided = options.certificate_file_userprovided[i]; 1620 TAILQ_INSERT_TAIL(preferred, id, next); 1621 } 1622 /* list of keys supported by the agent */ 1623 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1624 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1625 debug("%s: ssh_get_authentication_socket: %s", 1626 __func__, ssh_err(r)); 1627 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1628 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1629 debug("%s: ssh_fetch_identitylist: %s", 1630 __func__, ssh_err(r)); 1631 close(agent_fd); 1632 } else { 1633 for (j = 0; j < idlist->nkeys; j++) { 1634 found = 0; 1635 TAILQ_FOREACH(id, &files, next) { 1636 /* 1637 * agent keys from the config file are 1638 * preferred 1639 */ 1640 if (sshkey_equal(idlist->keys[j], id->key)) { 1641 TAILQ_REMOVE(&files, id, next); 1642 TAILQ_INSERT_TAIL(preferred, id, next); 1643 id->agent_fd = agent_fd; 1644 found = 1; 1645 break; 1646 } 1647 } 1648 if (!found && !options.identities_only) { 1649 id = xcalloc(1, sizeof(*id)); 1650 /* XXX "steals" key/comment from idlist */ 1651 id->key = idlist->keys[j]; 1652 id->filename = idlist->comments[j]; 1653 idlist->keys[j] = NULL; 1654 idlist->comments[j] = NULL; 1655 id->agent_fd = agent_fd; 1656 TAILQ_INSERT_TAIL(&agent, id, next); 1657 } 1658 } 1659 ssh_free_identitylist(idlist); 1660 /* append remaining agent keys */ 1661 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1662 TAILQ_REMOVE(&agent, id, next); 1663 TAILQ_INSERT_TAIL(preferred, id, next); 1664 } 1665 authctxt->agent_fd = agent_fd; 1666 } 1667 /* Prefer PKCS11 keys that are explicitly listed */ 1668 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1669 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1670 continue; 1671 found = 0; 1672 TAILQ_FOREACH(id2, &files, next) { 1673 if (id2->key == NULL || 1674 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1675 continue; 1676 if (sshkey_equal(id->key, id2->key)) { 1677 TAILQ_REMOVE(&files, id, next); 1678 TAILQ_INSERT_TAIL(preferred, id, next); 1679 found = 1; 1680 break; 1681 } 1682 } 1683 /* If IdentitiesOnly set and key not found then don't use it */ 1684 if (!found && options.identities_only) { 1685 TAILQ_REMOVE(&files, id, next); 1686 freezero(id, sizeof(*id)); 1687 } 1688 } 1689 /* append remaining keys from the config file */ 1690 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1691 TAILQ_REMOVE(&files, id, next); 1692 TAILQ_INSERT_TAIL(preferred, id, next); 1693 } 1694 /* finally, filter by PubkeyAcceptedKeyTypes */ 1695 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1696 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1697 debug("Skipping %s key %s - " 1698 "not in PubkeyAcceptedKeyTypes", 1699 sshkey_ssh_name(id->key), id->filename); 1700 TAILQ_REMOVE(preferred, id, next); 1701 sshkey_free(id->key); 1702 free(id->filename); 1703 memset(id, 0, sizeof(*id)); 1704 continue; 1705 } 1706 } 1707 /* List the keys we plan on using */ 1708 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1709 ident = format_identity(id); 1710 debug("Will attempt key: %s", ident); 1711 free(ident); 1712 } 1713 debug2("%s: done", __func__); 1714 } 1715 1716 static void 1717 pubkey_cleanup(struct ssh *ssh) 1718 { 1719 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1720 Identity *id; 1721 1722 if (authctxt->agent_fd != -1) { 1723 ssh_close_authentication_socket(authctxt->agent_fd); 1724 authctxt->agent_fd = -1; 1725 } 1726 for (id = TAILQ_FIRST(&authctxt->keys); id; 1727 id = TAILQ_FIRST(&authctxt->keys)) { 1728 TAILQ_REMOVE(&authctxt->keys, id, next); 1729 sshkey_free(id->key); 1730 free(id->filename); 1731 free(id); 1732 } 1733 } 1734 1735 static void 1736 pubkey_reset(Authctxt *authctxt) 1737 { 1738 Identity *id; 1739 1740 TAILQ_FOREACH(id, &authctxt->keys, next) 1741 id->tried = 0; 1742 } 1743 1744 static int 1745 try_identity(Identity *id) 1746 { 1747 if (!id->key) 1748 return (0); 1749 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1750 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1751 debug("Skipped %s key %s for RSA/MD5 server", 1752 sshkey_type(id->key), id->filename); 1753 return (0); 1754 } 1755 return 1; 1756 } 1757 1758 static int 1759 userauth_pubkey(struct ssh *ssh) 1760 { 1761 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1762 Identity *id; 1763 int sent = 0; 1764 char *ident; 1765 1766 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1767 if (id->tried++) 1768 return (0); 1769 /* move key to the end of the queue */ 1770 TAILQ_REMOVE(&authctxt->keys, id, next); 1771 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1772 /* 1773 * send a test message if we have the public key. for 1774 * encrypted keys we cannot do this and have to load the 1775 * private key instead 1776 */ 1777 if (id->key != NULL) { 1778 if (try_identity(id)) { 1779 ident = format_identity(id); 1780 debug("Offering public key: %s", ident); 1781 free(ident); 1782 sent = send_pubkey_test(ssh, id); 1783 } 1784 } else { 1785 debug("Trying private key: %s", id->filename); 1786 id->key = load_identity_file(id); 1787 if (id->key != NULL) { 1788 if (try_identity(id)) { 1789 id->isprivate = 1; 1790 sent = sign_and_send_pubkey(ssh, id); 1791 } 1792 sshkey_free(id->key); 1793 id->key = NULL; 1794 id->isprivate = 0; 1795 } 1796 } 1797 if (sent) 1798 return (sent); 1799 } 1800 return (0); 1801 } 1802 1803 /* 1804 * Send userauth request message specifying keyboard-interactive method. 1805 */ 1806 static int 1807 userauth_kbdint(struct ssh *ssh) 1808 { 1809 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1810 int r; 1811 1812 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1813 return 0; 1814 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1815 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1816 debug3("userauth_kbdint: disable: no info_req_seen"); 1817 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1818 return 0; 1819 } 1820 1821 debug2("userauth_kbdint"); 1822 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1823 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1824 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1825 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1826 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1827 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1828 options.kbd_interactive_devices : "")) != 0 || 1829 (r = sshpkt_send(ssh)) != 0) 1830 fatal("%s: %s", __func__, ssh_err(r)); 1831 1832 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1833 return 1; 1834 } 1835 1836 /* 1837 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1838 */ 1839 static int 1840 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1841 { 1842 Authctxt *authctxt = ssh->authctxt; 1843 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1844 char *response = NULL; 1845 u_char echo = 0; 1846 u_int num_prompts, i; 1847 int r; 1848 1849 debug2("input_userauth_info_req"); 1850 1851 if (authctxt == NULL) 1852 fatal("input_userauth_info_req: no authentication context"); 1853 1854 authctxt->info_req_seen = 1; 1855 1856 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1857 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1858 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1859 goto out; 1860 if (strlen(name) > 0) 1861 logit("%s", name); 1862 if (strlen(inst) > 0) 1863 logit("%s", inst); 1864 1865 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1866 goto out; 1867 /* 1868 * Begin to build info response packet based on prompts requested. 1869 * We commit to providing the correct number of responses, so if 1870 * further on we run into a problem that prevents this, we have to 1871 * be sure and clean this up and send a correct error response. 1872 */ 1873 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1874 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1875 goto out; 1876 1877 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1878 for (i = 0; i < num_prompts; i++) { 1879 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1880 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1881 goto out; 1882 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1883 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1884 goto out; 1885 freezero(response, strlen(response)); 1886 free(prompt); 1887 response = prompt = NULL; 1888 } 1889 /* done with parsing incoming message. */ 1890 if ((r = sshpkt_get_end(ssh)) != 0 || 1891 (r = sshpkt_add_padding(ssh, 64)) != 0) 1892 goto out; 1893 r = sshpkt_send(ssh); 1894 out: 1895 if (response) 1896 freezero(response, strlen(response)); 1897 free(prompt); 1898 free(name); 1899 free(inst); 1900 free(lang); 1901 return r; 1902 } 1903 1904 static int 1905 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1906 const u_char *data, size_t datalen) 1907 { 1908 struct sshbuf *b; 1909 struct stat st; 1910 pid_t pid; 1911 int r, to[2], from[2], status; 1912 int sock = ssh_packet_get_connection_in(ssh); 1913 u_char rversion = 0, version = 2; 1914 void (*osigchld)(int); 1915 1916 *sigp = NULL; 1917 *lenp = 0; 1918 1919 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1920 error("%s: not installed: %s", __func__, strerror(errno)); 1921 return -1; 1922 } 1923 if (fflush(stdout) != 0) { 1924 error("%s: fflush: %s", __func__, strerror(errno)); 1925 return -1; 1926 } 1927 if (pipe(to) == -1) { 1928 error("%s: pipe: %s", __func__, strerror(errno)); 1929 return -1; 1930 } 1931 if (pipe(from) == -1) { 1932 error("%s: pipe: %s", __func__, strerror(errno)); 1933 return -1; 1934 } 1935 if ((pid = fork()) == -1) { 1936 error("%s: fork: %s", __func__, strerror(errno)); 1937 return -1; 1938 } 1939 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1940 if (pid == 0) { 1941 close(from[0]); 1942 if (dup2(from[1], STDOUT_FILENO) == -1) 1943 fatal("%s: dup2: %s", __func__, strerror(errno)); 1944 close(to[1]); 1945 if (dup2(to[0], STDIN_FILENO) == -1) 1946 fatal("%s: dup2: %s", __func__, strerror(errno)); 1947 close(from[1]); 1948 close(to[0]); 1949 1950 if (dup2(sock, STDERR_FILENO + 1) == -1) 1951 fatal("%s: dup2: %s", __func__, strerror(errno)); 1952 sock = STDERR_FILENO + 1; 1953 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 1954 closefrom(sock + 1); 1955 1956 debug3("%s: [child] pid=%ld, exec %s", 1957 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1958 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1959 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1960 strerror(errno)); 1961 } 1962 close(from[1]); 1963 close(to[0]); 1964 sock = STDERR_FILENO + 1; 1965 1966 if ((b = sshbuf_new()) == NULL) 1967 fatal("%s: sshbuf_new failed", __func__); 1968 /* send # of sock, data to be signed */ 1969 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1970 (r = sshbuf_put_string(b, data, datalen)) != 0) 1971 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1972 if (ssh_msg_send(to[1], version, b) == -1) 1973 fatal("%s: couldn't send request", __func__); 1974 sshbuf_reset(b); 1975 r = ssh_msg_recv(from[0], b); 1976 close(from[0]); 1977 close(to[1]); 1978 if (r < 0) { 1979 error("%s: no reply", __func__); 1980 goto fail; 1981 } 1982 1983 errno = 0; 1984 while (waitpid(pid, &status, 0) == -1) { 1985 if (errno != EINTR) { 1986 error("%s: waitpid %ld: %s", 1987 __func__, (long)pid, strerror(errno)); 1988 goto fail; 1989 } 1990 } 1991 if (!WIFEXITED(status)) { 1992 error("%s: exited abnormally", __func__); 1993 goto fail; 1994 } 1995 if (WEXITSTATUS(status) != 0) { 1996 error("%s: exited with status %d", 1997 __func__, WEXITSTATUS(status)); 1998 goto fail; 1999 } 2000 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2001 error("%s: buffer error: %s", __func__, ssh_err(r)); 2002 goto fail; 2003 } 2004 if (rversion != version) { 2005 error("%s: bad version", __func__); 2006 goto fail; 2007 } 2008 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2009 error("%s: buffer error: %s", __func__, ssh_err(r)); 2010 fail: 2011 ssh_signal(SIGCHLD, osigchld); 2012 sshbuf_free(b); 2013 return -1; 2014 } 2015 ssh_signal(SIGCHLD, osigchld); 2016 sshbuf_free(b); 2017 2018 return 0; 2019 } 2020 2021 static int 2022 userauth_hostbased(struct ssh *ssh) 2023 { 2024 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2025 struct sshkey *private = NULL; 2026 struct sshbuf *b = NULL; 2027 u_char *sig = NULL, *keyblob = NULL; 2028 char *fp = NULL, *chost = NULL, *lname = NULL; 2029 size_t siglen = 0, keylen = 0; 2030 int i, r, success = 0; 2031 2032 if (authctxt->ktypes == NULL) { 2033 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2034 authctxt->ktypes = authctxt->oktypes; 2035 } 2036 2037 /* 2038 * Work through each listed type pattern in HostbasedKeyTypes, 2039 * trying each hostkey that matches the type in turn. 2040 */ 2041 for (;;) { 2042 if (authctxt->active_ktype == NULL) 2043 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2044 if (authctxt->active_ktype == NULL || 2045 *authctxt->active_ktype == '\0') 2046 break; 2047 debug3("%s: trying key type %s", __func__, 2048 authctxt->active_ktype); 2049 2050 /* check for a useful key */ 2051 private = NULL; 2052 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2053 if (authctxt->sensitive->keys[i] == NULL || 2054 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2055 continue; 2056 if (match_pattern_list( 2057 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2058 authctxt->active_ktype, 0) != 1) 2059 continue; 2060 /* we take and free the key */ 2061 private = authctxt->sensitive->keys[i]; 2062 authctxt->sensitive->keys[i] = NULL; 2063 break; 2064 } 2065 /* Found one */ 2066 if (private != NULL) 2067 break; 2068 /* No more keys of this type; advance */ 2069 authctxt->active_ktype = NULL; 2070 } 2071 if (private == NULL) { 2072 free(authctxt->oktypes); 2073 authctxt->oktypes = authctxt->ktypes = NULL; 2074 authctxt->active_ktype = NULL; 2075 debug("No more client hostkeys for hostbased authentication."); 2076 goto out; 2077 } 2078 2079 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2080 SSH_FP_DEFAULT)) == NULL) { 2081 error("%s: sshkey_fingerprint failed", __func__); 2082 goto out; 2083 } 2084 debug("%s: trying hostkey %s %s", 2085 __func__, sshkey_ssh_name(private), fp); 2086 2087 /* figure out a name for the client host */ 2088 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2089 if (lname == NULL) { 2090 error("%s: cannot get local ipaddr/name", __func__); 2091 goto out; 2092 } 2093 2094 /* XXX sshbuf_put_stringf? */ 2095 xasprintf(&chost, "%s.", lname); 2096 debug2("%s: chost %s", __func__, chost); 2097 2098 /* construct data */ 2099 if ((b = sshbuf_new()) == NULL) { 2100 error("%s: sshbuf_new failed", __func__); 2101 goto out; 2102 } 2103 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2104 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2105 goto out; 2106 } 2107 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2108 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2109 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2110 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2111 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2112 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2113 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2114 (r = sshbuf_put_cstring(b, chost)) != 0 || 2115 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2116 error("%s: buffer error: %s", __func__, ssh_err(r)); 2117 goto out; 2118 } 2119 2120 #ifdef DEBUG_PK 2121 sshbuf_dump(b, stderr); 2122 #endif 2123 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2124 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2125 error("sign using hostkey %s %s failed", 2126 sshkey_ssh_name(private), fp); 2127 goto out; 2128 } 2129 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2130 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2131 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2132 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2133 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2134 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2135 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2136 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2137 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2138 (r = sshpkt_send(ssh)) != 0) { 2139 error("%s: packet error: %s", __func__, ssh_err(r)); 2140 goto out; 2141 } 2142 success = 1; 2143 2144 out: 2145 if (sig != NULL) 2146 freezero(sig, siglen); 2147 free(keyblob); 2148 free(lname); 2149 free(fp); 2150 free(chost); 2151 sshkey_free(private); 2152 sshbuf_free(b); 2153 2154 return success; 2155 } 2156 2157 /* find auth method */ 2158 2159 /* 2160 * given auth method name, if configurable options permit this method fill 2161 * in auth_ident field and return true, otherwise return false. 2162 */ 2163 static int 2164 authmethod_is_enabled(Authmethod *method) 2165 { 2166 if (method == NULL) 2167 return 0; 2168 /* return false if options indicate this method is disabled */ 2169 if (method->enabled == NULL || *method->enabled == 0) 2170 return 0; 2171 /* return false if batch mode is enabled but method needs interactive mode */ 2172 if (method->batch_flag != NULL && *method->batch_flag != 0) 2173 return 0; 2174 return 1; 2175 } 2176 2177 static Authmethod * 2178 authmethod_lookup(const char *name) 2179 { 2180 Authmethod *method = NULL; 2181 if (name != NULL) 2182 for (method = authmethods; method->name != NULL; method++) 2183 if (strcmp(name, method->name) == 0) 2184 return method; 2185 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2186 return NULL; 2187 } 2188 2189 /* XXX internal state */ 2190 static Authmethod *current = NULL; 2191 static char *supported = NULL; 2192 static char *preferred = NULL; 2193 2194 /* 2195 * Given the authentication method list sent by the server, return the 2196 * next method we should try. If the server initially sends a nil list, 2197 * use a built-in default list. 2198 */ 2199 static Authmethod * 2200 authmethod_get(char *authlist) 2201 { 2202 char *name = NULL; 2203 u_int next; 2204 2205 /* Use a suitable default if we're passed a nil list. */ 2206 if (authlist == NULL || strlen(authlist) == 0) 2207 authlist = options.preferred_authentications; 2208 2209 if (supported == NULL || strcmp(authlist, supported) != 0) { 2210 debug3("start over, passed a different list %s", authlist); 2211 free(supported); 2212 supported = xstrdup(authlist); 2213 preferred = options.preferred_authentications; 2214 debug3("preferred %s", preferred); 2215 current = NULL; 2216 } else if (current != NULL && authmethod_is_enabled(current)) 2217 return current; 2218 2219 for (;;) { 2220 if ((name = match_list(preferred, supported, &next)) == NULL) { 2221 debug("No more authentication methods to try."); 2222 current = NULL; 2223 return NULL; 2224 } 2225 preferred += next; 2226 debug3("authmethod_lookup %s", name); 2227 debug3("remaining preferred: %s", preferred); 2228 if ((current = authmethod_lookup(name)) != NULL && 2229 authmethod_is_enabled(current)) { 2230 debug3("authmethod_is_enabled %s", name); 2231 debug("Next authentication method: %s", name); 2232 free(name); 2233 return current; 2234 } 2235 free(name); 2236 } 2237 } 2238 2239 static char * 2240 authmethods_get(void) 2241 { 2242 Authmethod *method = NULL; 2243 struct sshbuf *b; 2244 char *list; 2245 int r; 2246 2247 if ((b = sshbuf_new()) == NULL) 2248 fatal("%s: sshbuf_new failed", __func__); 2249 for (method = authmethods; method->name != NULL; method++) { 2250 if (authmethod_is_enabled(method)) { 2251 if ((r = sshbuf_putf(b, "%s%s", 2252 sshbuf_len(b) ? "," : "", method->name)) != 0) 2253 fatal("%s: buffer error: %s", 2254 __func__, ssh_err(r)); 2255 } 2256 } 2257 if ((list = sshbuf_dup_string(b)) == NULL) 2258 fatal("%s: sshbuf_dup_string failed", __func__); 2259 sshbuf_free(b); 2260 return list; 2261 } 2262