1 /* $OpenBSD: sshconnect2.c,v 1.320 2020/02/06 22:48:23 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 static char * 101 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 102 { 103 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 104 size_t maxlen; 105 struct hostkeys *hostkeys; 106 int ktype; 107 u_int i; 108 109 /* Find all hostkeys for this hostname */ 110 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 111 hostkeys = init_hostkeys(); 112 for (i = 0; i < options.num_user_hostfiles; i++) 113 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 114 for (i = 0; i < options.num_system_hostfiles; i++) 115 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 116 117 oavail = avail = xstrdup(options.hostkeyalgorithms); 118 maxlen = strlen(avail) + 1; 119 first = xmalloc(maxlen); 120 last = xmalloc(maxlen); 121 *first = *last = '\0'; 122 123 #define ALG_APPEND(to, from) \ 124 do { \ 125 if (*to != '\0') \ 126 strlcat(to, ",", maxlen); \ 127 strlcat(to, from, maxlen); \ 128 } while (0) 129 130 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 131 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 132 fatal("%s: unknown alg %s", __func__, alg); 133 if (lookup_key_in_hostkeys_by_type(hostkeys, 134 sshkey_type_plain(ktype), NULL)) 135 ALG_APPEND(first, alg); 136 else 137 ALG_APPEND(last, alg); 138 } 139 #undef ALG_APPEND 140 xasprintf(&ret, "%s%s%s", first, 141 (*first == '\0' || *last == '\0') ? "" : ",", last); 142 if (*first != '\0') 143 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 144 145 free(first); 146 free(last); 147 free(hostname); 148 free(oavail); 149 free_hostkeys(hostkeys); 150 151 return ret; 152 } 153 154 void 155 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 156 { 157 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 158 char *s, *all_key; 159 int r, use_known_hosts_order = 0; 160 161 xxx_host = host; 162 xxx_hostaddr = hostaddr; 163 164 /* 165 * If the user has not specified HostkeyAlgorithms, or has only 166 * appended or removed algorithms from that list then prefer algorithms 167 * that are in the list that are supported by known_hosts keys. 168 */ 169 if (options.hostkeyalgorithms == NULL || 170 options.hostkeyalgorithms[0] == '-' || 171 options.hostkeyalgorithms[0] == '+') 172 use_known_hosts_order = 1; 173 174 /* Expand or fill in HostkeyAlgorithms */ 175 all_key = sshkey_alg_list(0, 0, 1, ','); 176 if (kex_assemble_names(&options.hostkeyalgorithms, 177 kex_default_pk_alg(), all_key) != 0) 178 fatal("%s: kex_assemble_namelist", __func__); 179 free(all_key); 180 181 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 182 fatal("%s: kex_names_cat", __func__); 183 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 184 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 185 compat_cipher_proposal(options.ciphers); 186 myproposal[PROPOSAL_ENC_ALGS_STOC] = 187 compat_cipher_proposal(options.ciphers); 188 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 189 myproposal[PROPOSAL_COMP_ALGS_STOC] = 190 (char *)compression_alg_list(options.compression); 191 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 192 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 193 if (use_known_hosts_order) { 194 /* Query known_hosts and prefer algorithms that appear there */ 195 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 196 compat_pkalg_proposal( 197 order_hostkeyalgs(host, hostaddr, port)); 198 } else { 199 /* Use specified HostkeyAlgorithms exactly */ 200 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 201 compat_pkalg_proposal(options.hostkeyalgorithms); 202 } 203 204 if (options.rekey_limit || options.rekey_interval) 205 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 206 options.rekey_interval); 207 208 /* start key exchange */ 209 if ((r = kex_setup(ssh, myproposal)) != 0) 210 fatal("kex_setup: %s", ssh_err(r)); 211 #ifdef WITH_OPENSSL 212 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 213 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 214 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 215 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 216 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 217 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 218 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 219 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 220 #endif 221 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 222 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 223 ssh->kex->verify_host_key=&verify_host_key_callback; 224 225 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 226 227 /* remove ext-info from the KEX proposals for rekeying */ 228 myproposal[PROPOSAL_KEX_ALGS] = 229 compat_kex_proposal(options.kex_algorithms); 230 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 231 fatal("kex_prop2buf: %s", ssh_err(r)); 232 233 session_id2 = ssh->kex->session_id; 234 session_id2_len = ssh->kex->session_id_len; 235 236 #ifdef DEBUG_KEXDH 237 /* send 1st encrypted/maced/compressed message */ 238 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 239 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 240 (r = sshpkt_send(ssh)) != 0 || 241 (r = ssh_packet_write_wait(ssh)) != 0) 242 fatal("%s: %s", __func__, ssh_err(r)); 243 #endif 244 } 245 246 /* 247 * Authenticate user 248 */ 249 250 typedef struct cauthctxt Authctxt; 251 typedef struct cauthmethod Authmethod; 252 typedef struct identity Identity; 253 typedef struct idlist Idlist; 254 255 struct identity { 256 TAILQ_ENTRY(identity) next; 257 int agent_fd; /* >=0 if agent supports key */ 258 struct sshkey *key; /* public/private key */ 259 char *filename; /* comment for agent-only keys */ 260 int tried; 261 int isprivate; /* key points to the private key */ 262 int userprovided; 263 }; 264 TAILQ_HEAD(idlist, identity); 265 266 struct cauthctxt { 267 const char *server_user; 268 const char *local_user; 269 const char *host; 270 const char *service; 271 struct cauthmethod *method; 272 sig_atomic_t success; 273 char *authlist; 274 #ifdef GSSAPI 275 /* gssapi */ 276 gss_OID_set gss_supported_mechs; 277 u_int mech_tried; 278 #endif 279 /* pubkey */ 280 struct idlist keys; 281 int agent_fd; 282 /* hostbased */ 283 Sensitive *sensitive; 284 char *oktypes, *ktypes; 285 const char *active_ktype; 286 /* kbd-interactive */ 287 int info_req_seen; 288 int attempt_kbdint; 289 /* password */ 290 int attempt_passwd; 291 /* generic */ 292 void *methoddata; 293 }; 294 295 struct cauthmethod { 296 char *name; /* string to compare against server's list */ 297 int (*userauth)(struct ssh *ssh); 298 void (*cleanup)(struct ssh *ssh); 299 int *enabled; /* flag in option struct that enables method */ 300 int *batch_flag; /* flag in option struct that disables method */ 301 }; 302 303 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 304 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 305 static int input_userauth_success(int, u_int32_t, struct ssh *); 306 static int input_userauth_failure(int, u_int32_t, struct ssh *); 307 static int input_userauth_banner(int, u_int32_t, struct ssh *); 308 static int input_userauth_error(int, u_int32_t, struct ssh *); 309 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 310 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 311 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 312 313 static int userauth_none(struct ssh *); 314 static int userauth_pubkey(struct ssh *); 315 static int userauth_passwd(struct ssh *); 316 static int userauth_kbdint(struct ssh *); 317 static int userauth_hostbased(struct ssh *); 318 319 #ifdef GSSAPI 320 static int userauth_gssapi(struct ssh *); 321 static void userauth_gssapi_cleanup(struct ssh *); 322 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 323 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 324 static int input_gssapi_error(int, u_int32_t, struct ssh *); 325 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 326 #endif 327 328 void userauth(struct ssh *, char *); 329 330 static void pubkey_cleanup(struct ssh *); 331 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 332 static void pubkey_prepare(Authctxt *); 333 static void pubkey_reset(Authctxt *); 334 static struct sshkey *load_identity_file(Identity *); 335 336 static Authmethod *authmethod_get(char *authlist); 337 static Authmethod *authmethod_lookup(const char *name); 338 static char *authmethods_get(void); 339 340 Authmethod authmethods[] = { 341 #ifdef GSSAPI 342 {"gssapi-with-mic", 343 userauth_gssapi, 344 userauth_gssapi_cleanup, 345 &options.gss_authentication, 346 NULL}, 347 #endif 348 {"hostbased", 349 userauth_hostbased, 350 NULL, 351 &options.hostbased_authentication, 352 NULL}, 353 {"publickey", 354 userauth_pubkey, 355 NULL, 356 &options.pubkey_authentication, 357 NULL}, 358 {"keyboard-interactive", 359 userauth_kbdint, 360 NULL, 361 &options.kbd_interactive_authentication, 362 &options.batch_mode}, 363 {"password", 364 userauth_passwd, 365 NULL, 366 &options.password_authentication, 367 &options.batch_mode}, 368 {"none", 369 userauth_none, 370 NULL, 371 NULL, 372 NULL}, 373 {NULL, NULL, NULL, NULL, NULL} 374 }; 375 376 void 377 ssh_userauth2(struct ssh *ssh, const char *local_user, 378 const char *server_user, char *host, Sensitive *sensitive) 379 { 380 Authctxt authctxt; 381 int r; 382 383 if (options.challenge_response_authentication) 384 options.kbd_interactive_authentication = 1; 385 if (options.preferred_authentications == NULL) 386 options.preferred_authentications = authmethods_get(); 387 388 /* setup authentication context */ 389 memset(&authctxt, 0, sizeof(authctxt)); 390 authctxt.server_user = server_user; 391 authctxt.local_user = local_user; 392 authctxt.host = host; 393 authctxt.service = "ssh-connection"; /* service name */ 394 authctxt.success = 0; 395 authctxt.method = authmethod_lookup("none"); 396 authctxt.authlist = NULL; 397 authctxt.methoddata = NULL; 398 authctxt.sensitive = sensitive; 399 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 400 authctxt.info_req_seen = 0; 401 authctxt.attempt_kbdint = 0; 402 authctxt.attempt_passwd = 0; 403 #if GSSAPI 404 authctxt.gss_supported_mechs = NULL; 405 authctxt.mech_tried = 0; 406 #endif 407 authctxt.agent_fd = -1; 408 pubkey_prepare(&authctxt); 409 if (authctxt.method == NULL) { 410 fatal("%s: internal error: cannot send userauth none request", 411 __func__); 412 } 413 414 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 415 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 416 (r = sshpkt_send(ssh)) != 0) 417 fatal("%s: %s", __func__, ssh_err(r)); 418 419 ssh->authctxt = &authctxt; 420 ssh_dispatch_init(ssh, &input_userauth_error); 421 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 422 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 423 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 424 pubkey_cleanup(ssh); 425 ssh->authctxt = NULL; 426 427 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 428 429 if (!authctxt.success) 430 fatal("Authentication failed."); 431 debug("Authentication succeeded (%s).", authctxt.method->name); 432 } 433 434 /* ARGSUSED */ 435 static int 436 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 437 { 438 int r; 439 440 if (ssh_packet_remaining(ssh) > 0) { 441 char *reply; 442 443 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 444 goto out; 445 debug2("service_accept: %s", reply); 446 free(reply); 447 } else { 448 debug2("buggy server: service_accept w/o service"); 449 } 450 if ((r = sshpkt_get_end(ssh)) != 0) 451 goto out; 452 debug("SSH2_MSG_SERVICE_ACCEPT received"); 453 454 /* initial userauth request */ 455 userauth_none(ssh); 456 457 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 458 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 459 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 460 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 461 r = 0; 462 out: 463 return r; 464 } 465 466 /* ARGSUSED */ 467 static int 468 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 469 { 470 return kex_input_ext_info(type, seqnr, ssh); 471 } 472 473 void 474 userauth(struct ssh *ssh, char *authlist) 475 { 476 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 477 478 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 479 authctxt->method->cleanup(ssh); 480 481 free(authctxt->methoddata); 482 authctxt->methoddata = NULL; 483 if (authlist == NULL) { 484 authlist = authctxt->authlist; 485 } else { 486 free(authctxt->authlist); 487 authctxt->authlist = authlist; 488 } 489 for (;;) { 490 Authmethod *method = authmethod_get(authlist); 491 if (method == NULL) 492 fatal("%s@%s: Permission denied (%s).", 493 authctxt->server_user, authctxt->host, authlist); 494 authctxt->method = method; 495 496 /* reset the per method handler */ 497 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 498 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 499 500 /* and try new method */ 501 if (method->userauth(ssh) != 0) { 502 debug2("we sent a %s packet, wait for reply", method->name); 503 break; 504 } else { 505 debug2("we did not send a packet, disable method"); 506 method->enabled = NULL; 507 } 508 } 509 } 510 511 /* ARGSUSED */ 512 static int 513 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 514 { 515 fatal("%s: bad message during authentication: type %d", __func__, type); 516 return 0; 517 } 518 519 /* ARGSUSED */ 520 static int 521 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 522 { 523 char *msg = NULL; 524 size_t len; 525 int r; 526 527 debug3("%s", __func__); 528 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 529 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 530 goto out; 531 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 532 fmprintf(stderr, "%s", msg); 533 r = 0; 534 out: 535 free(msg); 536 return r; 537 } 538 539 /* ARGSUSED */ 540 static int 541 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 542 { 543 Authctxt *authctxt = ssh->authctxt; 544 545 if (authctxt == NULL) 546 fatal("%s: no authentication context", __func__); 547 free(authctxt->authlist); 548 authctxt->authlist = NULL; 549 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 550 authctxt->method->cleanup(ssh); 551 free(authctxt->methoddata); 552 authctxt->methoddata = NULL; 553 authctxt->success = 1; /* break out */ 554 return 0; 555 } 556 557 #if 0 558 static int 559 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 560 { 561 Authctxt *authctxt = ssh->authctxt; 562 563 if (authctxt == NULL) 564 fatal("%s: no authentication context", __func__); 565 566 fatal("Unexpected authentication success during %s.", 567 authctxt->method->name); 568 return 0; 569 } 570 #endif 571 572 /* ARGSUSED */ 573 static int 574 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 575 { 576 Authctxt *authctxt = ssh->authctxt; 577 char *authlist = NULL; 578 u_char partial; 579 580 if (authctxt == NULL) 581 fatal("input_userauth_failure: no authentication context"); 582 583 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 584 sshpkt_get_u8(ssh, &partial) != 0 || 585 sshpkt_get_end(ssh) != 0) 586 goto out; 587 588 if (partial != 0) { 589 verbose("Authenticated with partial success."); 590 /* reset state */ 591 pubkey_reset(authctxt); 592 } 593 debug("Authentications that can continue: %s", authlist); 594 595 userauth(ssh, authlist); 596 authlist = NULL; 597 out: 598 free(authlist); 599 return 0; 600 } 601 602 /* 603 * Format an identity for logging including filename, key type, fingerprint 604 * and location (agent, etc.). Caller must free. 605 */ 606 static char * 607 format_identity(Identity *id) 608 { 609 char *fp = NULL, *ret = NULL; 610 const char *note = ""; 611 612 if (id->key != NULL) { 613 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 614 SSH_FP_DEFAULT); 615 } 616 if (id->key) { 617 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 618 note = " token"; 619 else if (sshkey_is_sk(id->key)) 620 note = " authenticator"; 621 } 622 xasprintf(&ret, "%s %s%s%s%s%s%s", 623 id->filename, 624 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 625 fp ? fp : "", 626 id->userprovided ? " explicit" : "", note, 627 id->agent_fd != -1 ? " agent" : ""); 628 free(fp); 629 return ret; 630 } 631 632 /* ARGSUSED */ 633 static int 634 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 635 { 636 Authctxt *authctxt = ssh->authctxt; 637 struct sshkey *key = NULL; 638 Identity *id = NULL; 639 int pktype, found = 0, sent = 0; 640 size_t blen; 641 char *pkalg = NULL, *fp = NULL, *ident = NULL; 642 u_char *pkblob = NULL; 643 int r; 644 645 if (authctxt == NULL) 646 fatal("input_userauth_pk_ok: no authentication context"); 647 648 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 649 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 650 (r = sshpkt_get_end(ssh)) != 0) 651 goto done; 652 653 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 654 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 655 goto done; 656 } 657 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 658 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 659 goto done; 660 } 661 if (key->type != pktype) { 662 error("input_userauth_pk_ok: type mismatch " 663 "for decoded key (received %d, expected %d)", 664 key->type, pktype); 665 goto done; 666 } 667 668 /* 669 * search keys in the reverse order, because last candidate has been 670 * moved to the end of the queue. this also avoids confusion by 671 * duplicate keys 672 */ 673 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 674 if (sshkey_equal(key, id->key)) { 675 found = 1; 676 break; 677 } 678 } 679 if (!found || id == NULL) { 680 fp = sshkey_fingerprint(key, options.fingerprint_hash, 681 SSH_FP_DEFAULT); 682 error("%s: server replied with unknown key: %s %s", __func__, 683 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 684 goto done; 685 } 686 ident = format_identity(id); 687 debug("Server accepts key: %s", ident); 688 sent = sign_and_send_pubkey(ssh, id); 689 r = 0; 690 done: 691 sshkey_free(key); 692 free(ident); 693 free(fp); 694 free(pkalg); 695 free(pkblob); 696 697 /* try another method if we did not send a packet */ 698 if (r == 0 && sent == 0) 699 userauth(ssh, NULL); 700 return r; 701 } 702 703 #ifdef GSSAPI 704 static int 705 userauth_gssapi(struct ssh *ssh) 706 { 707 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 708 Gssctxt *gssctxt = NULL; 709 OM_uint32 min; 710 int r, ok = 0; 711 gss_OID mech = NULL; 712 713 /* Try one GSSAPI method at a time, rather than sending them all at 714 * once. */ 715 716 if (authctxt->gss_supported_mechs == NULL) 717 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 718 719 /* Check to see whether the mechanism is usable before we offer it */ 720 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 721 !ok) { 722 mech = &authctxt->gss_supported_mechs-> 723 elements[authctxt->mech_tried]; 724 /* My DER encoding requires length<128 */ 725 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 726 mech, authctxt->host)) { 727 ok = 1; /* Mechanism works */ 728 } else { 729 authctxt->mech_tried++; 730 } 731 } 732 733 if (!ok || mech == NULL) 734 return 0; 735 736 authctxt->methoddata=(void *)gssctxt; 737 738 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 739 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 740 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 741 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 742 (r = sshpkt_put_u32(ssh, 1)) != 0 || 743 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 744 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 745 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 746 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 747 (r = sshpkt_send(ssh)) != 0) 748 fatal("%s: %s", __func__, ssh_err(r)); 749 750 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 751 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 752 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 753 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 754 755 authctxt->mech_tried++; /* Move along to next candidate */ 756 757 return 1; 758 } 759 760 static void 761 userauth_gssapi_cleanup(struct ssh *ssh) 762 { 763 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 764 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 765 766 ssh_gssapi_delete_ctx(&gssctxt); 767 authctxt->methoddata = NULL; 768 769 free(authctxt->gss_supported_mechs); 770 authctxt->gss_supported_mechs = NULL; 771 } 772 773 static OM_uint32 774 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 775 { 776 Authctxt *authctxt = ssh->authctxt; 777 Gssctxt *gssctxt = authctxt->methoddata; 778 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 779 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 780 gss_buffer_desc gssbuf; 781 OM_uint32 status, ms, flags; 782 int r; 783 784 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 785 recv_tok, &send_tok, &flags); 786 787 if (send_tok.length > 0) { 788 u_char type = GSS_ERROR(status) ? 789 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 790 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 791 792 if ((r = sshpkt_start(ssh, type)) != 0 || 793 (r = sshpkt_put_string(ssh, send_tok.value, 794 send_tok.length)) != 0 || 795 (r = sshpkt_send(ssh)) != 0) 796 fatal("%s: %s", __func__, ssh_err(r)); 797 798 gss_release_buffer(&ms, &send_tok); 799 } 800 801 if (status == GSS_S_COMPLETE) { 802 /* send either complete or MIC, depending on mechanism */ 803 if (!(flags & GSS_C_INTEG_FLAG)) { 804 if ((r = sshpkt_start(ssh, 805 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 806 (r = sshpkt_send(ssh)) != 0) 807 fatal("%s: %s", __func__, ssh_err(r)); 808 } else { 809 struct sshbuf *b; 810 811 if ((b = sshbuf_new()) == NULL) 812 fatal("%s: sshbuf_new failed", __func__); 813 ssh_gssapi_buildmic(b, authctxt->server_user, 814 authctxt->service, "gssapi-with-mic"); 815 816 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 817 fatal("%s: sshbuf_mutable_ptr failed", __func__); 818 gssbuf.length = sshbuf_len(b); 819 820 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 821 822 if (!GSS_ERROR(status)) { 823 if ((r = sshpkt_start(ssh, 824 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 825 (r = sshpkt_put_string(ssh, mic.value, 826 mic.length)) != 0 || 827 (r = sshpkt_send(ssh)) != 0) 828 fatal("%s: %s", __func__, ssh_err(r)); 829 } 830 831 sshbuf_free(b); 832 gss_release_buffer(&ms, &mic); 833 } 834 } 835 836 return status; 837 } 838 839 /* ARGSUSED */ 840 static int 841 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 842 { 843 Authctxt *authctxt = ssh->authctxt; 844 Gssctxt *gssctxt; 845 size_t oidlen; 846 u_char *oidv = NULL; 847 int r; 848 849 if (authctxt == NULL) 850 fatal("input_gssapi_response: no authentication context"); 851 gssctxt = authctxt->methoddata; 852 853 /* Setup our OID */ 854 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 855 goto done; 856 857 if (oidlen <= 2 || 858 oidv[0] != SSH_GSS_OIDTYPE || 859 oidv[1] != oidlen - 2) { 860 debug("Badly encoded mechanism OID received"); 861 userauth(ssh, NULL); 862 goto ok; 863 } 864 865 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 866 fatal("Server returned different OID than expected"); 867 868 if ((r = sshpkt_get_end(ssh)) != 0) 869 goto done; 870 871 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 872 /* Start again with next method on list */ 873 debug("Trying to start again"); 874 userauth(ssh, NULL); 875 goto ok; 876 } 877 ok: 878 r = 0; 879 done: 880 free(oidv); 881 return r; 882 } 883 884 /* ARGSUSED */ 885 static int 886 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 887 { 888 Authctxt *authctxt = ssh->authctxt; 889 gss_buffer_desc recv_tok; 890 u_char *p = NULL; 891 size_t len; 892 OM_uint32 status; 893 int r; 894 895 if (authctxt == NULL) 896 fatal("input_gssapi_response: no authentication context"); 897 898 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 899 (r = sshpkt_get_end(ssh)) != 0) 900 goto out; 901 902 recv_tok.value = p; 903 recv_tok.length = len; 904 status = process_gssapi_token(ssh, &recv_tok); 905 906 /* Start again with the next method in the list */ 907 if (GSS_ERROR(status)) { 908 userauth(ssh, NULL); 909 /* ok */ 910 } 911 r = 0; 912 out: 913 free(p); 914 return r; 915 } 916 917 /* ARGSUSED */ 918 static int 919 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 920 { 921 Authctxt *authctxt = ssh->authctxt; 922 Gssctxt *gssctxt; 923 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 924 gss_buffer_desc recv_tok; 925 OM_uint32 ms; 926 u_char *p = NULL; 927 size_t len; 928 int r; 929 930 if (authctxt == NULL) 931 fatal("input_gssapi_response: no authentication context"); 932 gssctxt = authctxt->methoddata; 933 934 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 935 (r = sshpkt_get_end(ssh)) != 0) { 936 free(p); 937 return r; 938 } 939 940 /* Stick it into GSSAPI and see what it says */ 941 recv_tok.value = p; 942 recv_tok.length = len; 943 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 944 &recv_tok, &send_tok, NULL); 945 free(p); 946 gss_release_buffer(&ms, &send_tok); 947 948 /* Server will be returning a failed packet after this one */ 949 return 0; 950 } 951 952 /* ARGSUSED */ 953 static int 954 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 955 { 956 char *msg = NULL; 957 char *lang = NULL; 958 int r; 959 960 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 961 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 962 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 963 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 964 goto out; 965 r = sshpkt_get_end(ssh); 966 debug("Server GSSAPI Error:\n%s", msg); 967 out: 968 free(msg); 969 free(lang); 970 return r; 971 } 972 #endif /* GSSAPI */ 973 974 static int 975 userauth_none(struct ssh *ssh) 976 { 977 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 978 int r; 979 980 /* initial userauth request */ 981 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 982 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 983 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 984 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 985 (r = sshpkt_send(ssh)) != 0) 986 fatal("%s: %s", __func__, ssh_err(r)); 987 return 1; 988 } 989 990 static int 991 userauth_passwd(struct ssh *ssh) 992 { 993 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 994 char *password, *prompt = NULL; 995 const char *host = options.host_key_alias ? options.host_key_alias : 996 authctxt->host; 997 int r; 998 999 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1000 return 0; 1001 1002 if (authctxt->attempt_passwd != 1) 1003 error("Permission denied, please try again."); 1004 1005 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1006 password = read_passphrase(prompt, 0); 1007 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1008 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1009 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1010 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1011 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1012 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1013 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1014 (r = sshpkt_send(ssh)) != 0) 1015 fatal("%s: %s", __func__, ssh_err(r)); 1016 1017 free(prompt); 1018 if (password != NULL) 1019 freezero(password, strlen(password)); 1020 1021 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1022 &input_userauth_passwd_changereq); 1023 1024 return 1; 1025 } 1026 1027 /* 1028 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1029 */ 1030 /* ARGSUSED */ 1031 static int 1032 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1033 { 1034 Authctxt *authctxt = ssh->authctxt; 1035 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1036 char prompt[256]; 1037 const char *host; 1038 int r; 1039 1040 debug2("input_userauth_passwd_changereq"); 1041 1042 if (authctxt == NULL) 1043 fatal("input_userauth_passwd_changereq: " 1044 "no authentication context"); 1045 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1046 1047 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1048 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1049 goto out; 1050 if (strlen(info) > 0) 1051 logit("%s", info); 1052 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1053 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1054 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1055 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1056 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1057 goto out; 1058 1059 snprintf(prompt, sizeof(prompt), 1060 "Enter %.30s@%.128s's old password: ", 1061 authctxt->server_user, host); 1062 password = read_passphrase(prompt, 0); 1063 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1064 goto out; 1065 1066 freezero(password, strlen(password)); 1067 password = NULL; 1068 while (password == NULL) { 1069 snprintf(prompt, sizeof(prompt), 1070 "Enter %.30s@%.128s's new password: ", 1071 authctxt->server_user, host); 1072 password = read_passphrase(prompt, RP_ALLOW_EOF); 1073 if (password == NULL) { 1074 /* bail out */ 1075 r = 0; 1076 goto out; 1077 } 1078 snprintf(prompt, sizeof(prompt), 1079 "Retype %.30s@%.128s's new password: ", 1080 authctxt->server_user, host); 1081 retype = read_passphrase(prompt, 0); 1082 if (strcmp(password, retype) != 0) { 1083 freezero(password, strlen(password)); 1084 logit("Mismatch; try again, EOF to quit."); 1085 password = NULL; 1086 } 1087 freezero(retype, strlen(retype)); 1088 } 1089 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1090 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1091 (r = sshpkt_send(ssh)) != 0) 1092 goto out; 1093 1094 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1095 &input_userauth_passwd_changereq); 1096 r = 0; 1097 out: 1098 if (password) 1099 freezero(password, strlen(password)); 1100 free(info); 1101 free(lang); 1102 return r; 1103 } 1104 1105 /* 1106 * Select an algorithm for publickey signatures. 1107 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1108 * 1109 * Call with ssh==NULL to ignore server-sig-algs extension list and 1110 * only attempt with the key's base signature type. 1111 */ 1112 static char * 1113 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1114 { 1115 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1116 1117 /* 1118 * The signature algorithm will only differ from the key algorithm 1119 * for RSA keys/certs and when the server advertises support for 1120 * newer (SHA2) algorithms. 1121 */ 1122 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1123 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1124 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1125 /* Filter base key signature alg against our configuration */ 1126 return match_list(sshkey_ssh_name(key), 1127 options.pubkey_key_types, NULL); 1128 } 1129 1130 /* 1131 * For RSA keys/certs, since these might have a different sig type: 1132 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1133 * that also appears in the supported signature algorithms list from 1134 * the server. 1135 */ 1136 oallowed = allowed = xstrdup(options.pubkey_key_types); 1137 while ((cp = strsep(&allowed, ",")) != NULL) { 1138 if (sshkey_type_from_name(cp) != key->type) 1139 continue; 1140 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1141 if (tmp != NULL) 1142 alg = xstrdup(cp); 1143 free(tmp); 1144 if (alg != NULL) 1145 break; 1146 } 1147 free(oallowed); 1148 return alg; 1149 } 1150 1151 static int 1152 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1153 const u_char *data, size_t datalen, u_int compat, const char *alg) 1154 { 1155 struct sshkey *sign_key = NULL, *prv = NULL; 1156 int r = SSH_ERR_INTERNAL_ERROR; 1157 struct notifier_ctx *notifier = NULL; 1158 char *fp = NULL; 1159 1160 *sigp = NULL; 1161 *lenp = 0; 1162 1163 /* The agent supports this key. */ 1164 if (id->key != NULL && id->agent_fd != -1) { 1165 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1166 data, datalen, alg, compat); 1167 } 1168 1169 /* 1170 * We have already loaded the private key or the private key is 1171 * stored in external hardware. 1172 */ 1173 if (id->key != NULL && 1174 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1175 sign_key = id->key; 1176 } else { 1177 /* Load the private key from the file. */ 1178 if ((prv = load_identity_file(id)) == NULL) 1179 return SSH_ERR_KEY_NOT_FOUND; 1180 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1181 error("%s: private key %s contents do not match public", 1182 __func__, id->filename); 1183 r = SSH_ERR_KEY_NOT_FOUND; 1184 goto out; 1185 } 1186 sign_key = prv; 1187 if (sshkey_is_sk(sign_key) && 1188 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1189 /* XXX match batch mode should just skip these keys? */ 1190 if ((fp = sshkey_fingerprint(sign_key, 1191 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1192 fatal("%s: sshkey_fingerprint", __func__); 1193 notifier = notify_start(options.batch_mode, 1194 "Confirm user presence for key %s %s", 1195 sshkey_type(sign_key), fp); 1196 free(fp); 1197 } 1198 } 1199 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1200 alg, options.sk_provider, compat)) != 0) { 1201 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1202 goto out; 1203 } 1204 /* 1205 * PKCS#11 tokens may not support all signature algorithms, 1206 * so check what we get back. 1207 */ 1208 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1209 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1210 goto out; 1211 } 1212 /* success */ 1213 r = 0; 1214 out: 1215 notify_complete(notifier); 1216 sshkey_free(prv); 1217 return r; 1218 } 1219 1220 static int 1221 id_filename_matches(Identity *id, Identity *private_id) 1222 { 1223 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1224 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1225 size_t i, slen; 1226 1227 if (strcmp(id->filename, private_id->filename) == 0) 1228 return 1; 1229 for (i = 0; suffixes[i]; i++) { 1230 slen = strlen(suffixes[i]); 1231 if (len > slen && plen == len - slen && 1232 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1233 memcmp(id->filename, private_id->filename, plen) == 0) 1234 return 1; 1235 } 1236 return 0; 1237 } 1238 1239 static int 1240 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1241 { 1242 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1243 struct sshbuf *b = NULL; 1244 Identity *private_id, *sign_id = NULL; 1245 u_char *signature = NULL; 1246 size_t slen = 0, skip = 0; 1247 int r, fallback_sigtype, sent = 0; 1248 char *alg = NULL, *fp = NULL; 1249 const char *loc = ""; 1250 1251 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1252 SSH_FP_DEFAULT)) == NULL) 1253 return 0; 1254 1255 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1256 1257 /* 1258 * If the key is an certificate, try to find a matching private key 1259 * and use it to complete the signature. 1260 * If no such private key exists, fall back to trying the certificate 1261 * key itself in case it has a private half already loaded. 1262 * This will try to set sign_id to the private key that will perform 1263 * the signature. 1264 */ 1265 if (sshkey_is_cert(id->key)) { 1266 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1267 if (sshkey_equal_public(id->key, private_id->key) && 1268 id->key->type != private_id->key->type) { 1269 sign_id = private_id; 1270 break; 1271 } 1272 } 1273 /* 1274 * Exact key matches are preferred, but also allow 1275 * filename matches for non-PKCS#11/agent keys that 1276 * didn't load public keys. This supports the case 1277 * of keeping just a private key file and public 1278 * certificate on disk. 1279 */ 1280 if (sign_id == NULL && 1281 !id->isprivate && id->agent_fd == -1 && 1282 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1283 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1284 if (private_id->key == NULL && 1285 id_filename_matches(id, private_id)) { 1286 sign_id = private_id; 1287 break; 1288 } 1289 } 1290 } 1291 if (sign_id != NULL) { 1292 debug2("%s: using private key \"%s\"%s for " 1293 "certificate", __func__, id->filename, 1294 id->agent_fd != -1 ? " from agent" : ""); 1295 } else { 1296 debug("%s: no separate private key for certificate " 1297 "\"%s\"", __func__, id->filename); 1298 } 1299 } 1300 1301 /* 1302 * If the above didn't select another identity to do the signing 1303 * then default to the one we started with. 1304 */ 1305 if (sign_id == NULL) 1306 sign_id = id; 1307 1308 /* assemble and sign data */ 1309 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1310 free(alg); 1311 slen = 0; 1312 signature = NULL; 1313 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1314 id->key)) == NULL) { 1315 error("%s: no mutual signature supported", __func__); 1316 goto out; 1317 } 1318 debug3("%s: signing using %s %s", __func__, alg, fp); 1319 1320 sshbuf_free(b); 1321 if ((b = sshbuf_new()) == NULL) 1322 fatal("%s: sshbuf_new failed", __func__); 1323 if (datafellows & SSH_OLD_SESSIONID) { 1324 if ((r = sshbuf_put(b, session_id2, 1325 session_id2_len)) != 0) { 1326 fatal("%s: sshbuf_put: %s", 1327 __func__, ssh_err(r)); 1328 } 1329 } else { 1330 if ((r = sshbuf_put_string(b, session_id2, 1331 session_id2_len)) != 0) { 1332 fatal("%s: sshbuf_put_string: %s", 1333 __func__, ssh_err(r)); 1334 } 1335 } 1336 skip = sshbuf_len(b); 1337 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1338 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1339 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1340 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1341 (r = sshbuf_put_u8(b, 1)) != 0 || 1342 (r = sshbuf_put_cstring(b, alg)) != 0 || 1343 (r = sshkey_puts(id->key, b)) != 0) { 1344 fatal("%s: assemble signed data: %s", 1345 __func__, ssh_err(r)); 1346 } 1347 1348 /* generate signature */ 1349 r = identity_sign(sign_id, &signature, &slen, 1350 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1351 if (r == 0) 1352 break; 1353 else if (r == SSH_ERR_KEY_NOT_FOUND) 1354 goto out; /* soft failure */ 1355 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1356 !fallback_sigtype) { 1357 if (sign_id->agent_fd != -1) 1358 loc = "agent "; 1359 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1360 loc = "token "; 1361 logit("%skey %s %s returned incorrect signature type", 1362 loc, sshkey_type(id->key), fp); 1363 continue; 1364 } 1365 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1366 sshkey_type(sign_id->key), sign_id->filename, 1367 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1368 goto out; 1369 } 1370 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1371 fatal("%s: no signature", __func__); 1372 1373 /* append signature */ 1374 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1375 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1376 1377 #ifdef DEBUG_PK 1378 sshbuf_dump(b, stderr); 1379 #endif 1380 /* skip session id and packet type */ 1381 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1382 fatal("%s: consume: %s", __func__, ssh_err(r)); 1383 1384 /* put remaining data from buffer into packet */ 1385 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1386 (r = sshpkt_putb(ssh, b)) != 0 || 1387 (r = sshpkt_send(ssh)) != 0) 1388 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1389 1390 /* success */ 1391 sent = 1; 1392 1393 out: 1394 free(fp); 1395 free(alg); 1396 sshbuf_free(b); 1397 freezero(signature, slen); 1398 return sent; 1399 } 1400 1401 static int 1402 send_pubkey_test(struct ssh *ssh, Identity *id) 1403 { 1404 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1405 u_char *blob = NULL; 1406 char *alg = NULL; 1407 size_t bloblen; 1408 u_int have_sig = 0; 1409 int sent = 0, r; 1410 1411 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1412 debug("%s: no mutual signature algorithm", __func__); 1413 goto out; 1414 } 1415 1416 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1417 /* we cannot handle this key */ 1418 debug3("%s: cannot handle key", __func__); 1419 goto out; 1420 } 1421 /* register callback for USERAUTH_PK_OK message */ 1422 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1423 1424 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1425 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1426 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1427 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1428 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1429 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1430 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1431 (r = sshpkt_send(ssh)) != 0) 1432 fatal("%s: %s", __func__, ssh_err(r)); 1433 sent = 1; 1434 1435 out: 1436 free(alg); 1437 free(blob); 1438 return sent; 1439 } 1440 1441 static struct sshkey * 1442 load_identity_file(Identity *id) 1443 { 1444 struct sshkey *private = NULL; 1445 char prompt[300], *passphrase, *comment; 1446 int r, quit = 0, i; 1447 struct stat st; 1448 1449 if (stat(id->filename, &st) == -1) { 1450 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1451 id->filename, strerror(errno)); 1452 return NULL; 1453 } 1454 snprintf(prompt, sizeof prompt, 1455 "Enter passphrase for key '%.100s': ", id->filename); 1456 for (i = 0; i <= options.number_of_password_prompts; i++) { 1457 if (i == 0) 1458 passphrase = ""; 1459 else { 1460 passphrase = read_passphrase(prompt, 0); 1461 if (*passphrase == '\0') { 1462 debug2("no passphrase given, try next key"); 1463 free(passphrase); 1464 break; 1465 } 1466 } 1467 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1468 passphrase, &private, &comment))) { 1469 case 0: 1470 break; 1471 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1472 if (options.batch_mode) { 1473 quit = 1; 1474 break; 1475 } 1476 if (i != 0) 1477 debug2("bad passphrase given, try again..."); 1478 break; 1479 case SSH_ERR_SYSTEM_ERROR: 1480 if (errno == ENOENT) { 1481 debug2("Load key \"%s\": %s", 1482 id->filename, ssh_err(r)); 1483 quit = 1; 1484 break; 1485 } 1486 /* FALLTHROUGH */ 1487 default: 1488 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1489 quit = 1; 1490 break; 1491 } 1492 if (private != NULL && sshkey_is_sk(private) && 1493 options.sk_provider == NULL) { 1494 debug("key \"%s\" is an authenticator-hosted key, " 1495 "but no provider specified", id->filename); 1496 sshkey_free(private); 1497 private = NULL; 1498 quit = 1; 1499 } 1500 if (!quit && private != NULL && id->agent_fd == -1 && 1501 !(id->key && id->isprivate)) 1502 maybe_add_key_to_agent(id->filename, private, comment, 1503 passphrase); 1504 if (i > 0) 1505 freezero(passphrase, strlen(passphrase)); 1506 free(comment); 1507 if (private != NULL || quit) 1508 break; 1509 } 1510 return private; 1511 } 1512 1513 static int 1514 key_type_allowed_by_config(struct sshkey *key) 1515 { 1516 if (match_pattern_list(sshkey_ssh_name(key), 1517 options.pubkey_key_types, 0) == 1) 1518 return 1; 1519 1520 /* RSA keys/certs might be allowed by alternate signature types */ 1521 switch (key->type) { 1522 case KEY_RSA: 1523 if (match_pattern_list("rsa-sha2-512", 1524 options.pubkey_key_types, 0) == 1) 1525 return 1; 1526 if (match_pattern_list("rsa-sha2-256", 1527 options.pubkey_key_types, 0) == 1) 1528 return 1; 1529 break; 1530 case KEY_RSA_CERT: 1531 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1532 options.pubkey_key_types, 0) == 1) 1533 return 1; 1534 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1535 options.pubkey_key_types, 0) == 1) 1536 return 1; 1537 break; 1538 } 1539 return 0; 1540 } 1541 1542 1543 /* 1544 * try keys in the following order: 1545 * 1. certificates listed in the config file 1546 * 2. other input certificates 1547 * 3. agent keys that are found in the config file 1548 * 4. other agent keys 1549 * 5. keys that are only listed in the config file 1550 */ 1551 static void 1552 pubkey_prepare(Authctxt *authctxt) 1553 { 1554 struct identity *id, *id2, *tmp; 1555 struct idlist agent, files, *preferred; 1556 struct sshkey *key; 1557 int agent_fd = -1, i, r, found; 1558 size_t j; 1559 struct ssh_identitylist *idlist; 1560 char *ident; 1561 1562 TAILQ_INIT(&agent); /* keys from the agent */ 1563 TAILQ_INIT(&files); /* keys from the config file */ 1564 preferred = &authctxt->keys; 1565 TAILQ_INIT(preferred); /* preferred order of keys */ 1566 1567 /* list of keys stored in the filesystem and PKCS#11 */ 1568 for (i = 0; i < options.num_identity_files; i++) { 1569 key = options.identity_keys[i]; 1570 if (key && key->cert && 1571 key->cert->type != SSH2_CERT_TYPE_USER) { 1572 debug("%s: ignoring certificate %s: not a user " 1573 "certificate", __func__, 1574 options.identity_files[i]); 1575 continue; 1576 } 1577 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1578 debug("%s: ignoring authenticator-hosted key %s as no " 1579 "SecurityKeyProvider has been specified", 1580 __func__, options.identity_files[i]); 1581 continue; 1582 } 1583 options.identity_keys[i] = NULL; 1584 id = xcalloc(1, sizeof(*id)); 1585 id->agent_fd = -1; 1586 id->key = key; 1587 id->filename = xstrdup(options.identity_files[i]); 1588 id->userprovided = options.identity_file_userprovided[i]; 1589 TAILQ_INSERT_TAIL(&files, id, next); 1590 } 1591 /* list of certificates specified by user */ 1592 for (i = 0; i < options.num_certificate_files; i++) { 1593 key = options.certificates[i]; 1594 if (!sshkey_is_cert(key) || key->cert == NULL || 1595 key->cert->type != SSH2_CERT_TYPE_USER) { 1596 debug("%s: ignoring certificate %s: not a user " 1597 "certificate", __func__, 1598 options.identity_files[i]); 1599 continue; 1600 } 1601 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1602 debug("%s: ignoring authenticator-hosted key " 1603 "certificate %s as no " 1604 "SecurityKeyProvider has been specified", 1605 __func__, options.identity_files[i]); 1606 continue; 1607 } 1608 id = xcalloc(1, sizeof(*id)); 1609 id->agent_fd = -1; 1610 id->key = key; 1611 id->filename = xstrdup(options.certificate_files[i]); 1612 id->userprovided = options.certificate_file_userprovided[i]; 1613 TAILQ_INSERT_TAIL(preferred, id, next); 1614 } 1615 /* list of keys supported by the agent */ 1616 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1617 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1618 debug("%s: ssh_get_authentication_socket: %s", 1619 __func__, ssh_err(r)); 1620 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1621 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1622 debug("%s: ssh_fetch_identitylist: %s", 1623 __func__, ssh_err(r)); 1624 close(agent_fd); 1625 } else { 1626 for (j = 0; j < idlist->nkeys; j++) { 1627 found = 0; 1628 TAILQ_FOREACH(id, &files, next) { 1629 /* 1630 * agent keys from the config file are 1631 * preferred 1632 */ 1633 if (sshkey_equal(idlist->keys[j], id->key)) { 1634 TAILQ_REMOVE(&files, id, next); 1635 TAILQ_INSERT_TAIL(preferred, id, next); 1636 id->agent_fd = agent_fd; 1637 found = 1; 1638 break; 1639 } 1640 } 1641 if (!found && !options.identities_only) { 1642 id = xcalloc(1, sizeof(*id)); 1643 /* XXX "steals" key/comment from idlist */ 1644 id->key = idlist->keys[j]; 1645 id->filename = idlist->comments[j]; 1646 idlist->keys[j] = NULL; 1647 idlist->comments[j] = NULL; 1648 id->agent_fd = agent_fd; 1649 TAILQ_INSERT_TAIL(&agent, id, next); 1650 } 1651 } 1652 ssh_free_identitylist(idlist); 1653 /* append remaining agent keys */ 1654 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1655 TAILQ_REMOVE(&agent, id, next); 1656 TAILQ_INSERT_TAIL(preferred, id, next); 1657 } 1658 authctxt->agent_fd = agent_fd; 1659 } 1660 /* Prefer PKCS11 keys that are explicitly listed */ 1661 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1662 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1663 continue; 1664 found = 0; 1665 TAILQ_FOREACH(id2, &files, next) { 1666 if (id2->key == NULL || 1667 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1668 continue; 1669 if (sshkey_equal(id->key, id2->key)) { 1670 TAILQ_REMOVE(&files, id, next); 1671 TAILQ_INSERT_TAIL(preferred, id, next); 1672 found = 1; 1673 break; 1674 } 1675 } 1676 /* If IdentitiesOnly set and key not found then don't use it */ 1677 if (!found && options.identities_only) { 1678 TAILQ_REMOVE(&files, id, next); 1679 freezero(id, sizeof(*id)); 1680 } 1681 } 1682 /* append remaining keys from the config file */ 1683 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1684 TAILQ_REMOVE(&files, id, next); 1685 TAILQ_INSERT_TAIL(preferred, id, next); 1686 } 1687 /* finally, filter by PubkeyAcceptedKeyTypes */ 1688 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1689 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1690 debug("Skipping %s key %s - " 1691 "not in PubkeyAcceptedKeyTypes", 1692 sshkey_ssh_name(id->key), id->filename); 1693 TAILQ_REMOVE(preferred, id, next); 1694 sshkey_free(id->key); 1695 free(id->filename); 1696 memset(id, 0, sizeof(*id)); 1697 continue; 1698 } 1699 } 1700 /* List the keys we plan on using */ 1701 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1702 ident = format_identity(id); 1703 debug("Will attempt key: %s", ident); 1704 free(ident); 1705 } 1706 debug2("%s: done", __func__); 1707 } 1708 1709 static void 1710 pubkey_cleanup(struct ssh *ssh) 1711 { 1712 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1713 Identity *id; 1714 1715 if (authctxt->agent_fd != -1) { 1716 ssh_close_authentication_socket(authctxt->agent_fd); 1717 authctxt->agent_fd = -1; 1718 } 1719 for (id = TAILQ_FIRST(&authctxt->keys); id; 1720 id = TAILQ_FIRST(&authctxt->keys)) { 1721 TAILQ_REMOVE(&authctxt->keys, id, next); 1722 sshkey_free(id->key); 1723 free(id->filename); 1724 free(id); 1725 } 1726 } 1727 1728 static void 1729 pubkey_reset(Authctxt *authctxt) 1730 { 1731 Identity *id; 1732 1733 TAILQ_FOREACH(id, &authctxt->keys, next) 1734 id->tried = 0; 1735 } 1736 1737 static int 1738 try_identity(Identity *id) 1739 { 1740 if (!id->key) 1741 return (0); 1742 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1743 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1744 debug("Skipped %s key %s for RSA/MD5 server", 1745 sshkey_type(id->key), id->filename); 1746 return (0); 1747 } 1748 return 1; 1749 } 1750 1751 static int 1752 userauth_pubkey(struct ssh *ssh) 1753 { 1754 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1755 Identity *id; 1756 int sent = 0; 1757 char *ident; 1758 1759 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1760 if (id->tried++) 1761 return (0); 1762 /* move key to the end of the queue */ 1763 TAILQ_REMOVE(&authctxt->keys, id, next); 1764 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1765 /* 1766 * send a test message if we have the public key. for 1767 * encrypted keys we cannot do this and have to load the 1768 * private key instead 1769 */ 1770 if (id->key != NULL) { 1771 if (try_identity(id)) { 1772 ident = format_identity(id); 1773 debug("Offering public key: %s", ident); 1774 free(ident); 1775 sent = send_pubkey_test(ssh, id); 1776 } 1777 } else { 1778 debug("Trying private key: %s", id->filename); 1779 id->key = load_identity_file(id); 1780 if (id->key != NULL) { 1781 if (try_identity(id)) { 1782 id->isprivate = 1; 1783 sent = sign_and_send_pubkey(ssh, id); 1784 } 1785 sshkey_free(id->key); 1786 id->key = NULL; 1787 id->isprivate = 0; 1788 } 1789 } 1790 if (sent) 1791 return (sent); 1792 } 1793 return (0); 1794 } 1795 1796 /* 1797 * Send userauth request message specifying keyboard-interactive method. 1798 */ 1799 static int 1800 userauth_kbdint(struct ssh *ssh) 1801 { 1802 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1803 int r; 1804 1805 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1806 return 0; 1807 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1808 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1809 debug3("userauth_kbdint: disable: no info_req_seen"); 1810 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1811 return 0; 1812 } 1813 1814 debug2("userauth_kbdint"); 1815 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1816 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1817 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1818 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1819 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1820 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1821 options.kbd_interactive_devices : "")) != 0 || 1822 (r = sshpkt_send(ssh)) != 0) 1823 fatal("%s: %s", __func__, ssh_err(r)); 1824 1825 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1826 return 1; 1827 } 1828 1829 /* 1830 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1831 */ 1832 static int 1833 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1834 { 1835 Authctxt *authctxt = ssh->authctxt; 1836 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1837 char *response = NULL; 1838 u_char echo = 0; 1839 u_int num_prompts, i; 1840 int r; 1841 1842 debug2("input_userauth_info_req"); 1843 1844 if (authctxt == NULL) 1845 fatal("input_userauth_info_req: no authentication context"); 1846 1847 authctxt->info_req_seen = 1; 1848 1849 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1850 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1851 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1852 goto out; 1853 if (strlen(name) > 0) 1854 logit("%s", name); 1855 if (strlen(inst) > 0) 1856 logit("%s", inst); 1857 1858 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1859 goto out; 1860 /* 1861 * Begin to build info response packet based on prompts requested. 1862 * We commit to providing the correct number of responses, so if 1863 * further on we run into a problem that prevents this, we have to 1864 * be sure and clean this up and send a correct error response. 1865 */ 1866 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1867 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1868 goto out; 1869 1870 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1871 for (i = 0; i < num_prompts; i++) { 1872 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1873 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1874 goto out; 1875 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1876 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1877 goto out; 1878 freezero(response, strlen(response)); 1879 free(prompt); 1880 response = prompt = NULL; 1881 } 1882 /* done with parsing incoming message. */ 1883 if ((r = sshpkt_get_end(ssh)) != 0 || 1884 (r = sshpkt_add_padding(ssh, 64)) != 0) 1885 goto out; 1886 r = sshpkt_send(ssh); 1887 out: 1888 if (response) 1889 freezero(response, strlen(response)); 1890 free(prompt); 1891 free(name); 1892 free(inst); 1893 free(lang); 1894 return r; 1895 } 1896 1897 static int 1898 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1899 const u_char *data, size_t datalen) 1900 { 1901 struct sshbuf *b; 1902 struct stat st; 1903 pid_t pid; 1904 int r, to[2], from[2], status; 1905 int sock = ssh_packet_get_connection_in(ssh); 1906 u_char rversion = 0, version = 2; 1907 void (*osigchld)(int); 1908 1909 *sigp = NULL; 1910 *lenp = 0; 1911 1912 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1913 error("%s: not installed: %s", __func__, strerror(errno)); 1914 return -1; 1915 } 1916 if (fflush(stdout) != 0) { 1917 error("%s: fflush: %s", __func__, strerror(errno)); 1918 return -1; 1919 } 1920 if (pipe(to) == -1) { 1921 error("%s: pipe: %s", __func__, strerror(errno)); 1922 return -1; 1923 } 1924 if (pipe(from) == -1) { 1925 error("%s: pipe: %s", __func__, strerror(errno)); 1926 return -1; 1927 } 1928 if ((pid = fork()) == -1) { 1929 error("%s: fork: %s", __func__, strerror(errno)); 1930 return -1; 1931 } 1932 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1933 if (pid == 0) { 1934 close(from[0]); 1935 if (dup2(from[1], STDOUT_FILENO) == -1) 1936 fatal("%s: dup2: %s", __func__, strerror(errno)); 1937 close(to[1]); 1938 if (dup2(to[0], STDIN_FILENO) == -1) 1939 fatal("%s: dup2: %s", __func__, strerror(errno)); 1940 close(from[1]); 1941 close(to[0]); 1942 1943 if (dup2(sock, STDERR_FILENO + 1) == -1) 1944 fatal("%s: dup2: %s", __func__, strerror(errno)); 1945 sock = STDERR_FILENO + 1; 1946 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 1947 closefrom(sock + 1); 1948 1949 debug3("%s: [child] pid=%ld, exec %s", 1950 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1951 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1952 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1953 strerror(errno)); 1954 } 1955 close(from[1]); 1956 close(to[0]); 1957 sock = STDERR_FILENO + 1; 1958 1959 if ((b = sshbuf_new()) == NULL) 1960 fatal("%s: sshbuf_new failed", __func__); 1961 /* send # of sock, data to be signed */ 1962 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1963 (r = sshbuf_put_string(b, data, datalen)) != 0) 1964 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1965 if (ssh_msg_send(to[1], version, b) == -1) 1966 fatal("%s: couldn't send request", __func__); 1967 sshbuf_reset(b); 1968 r = ssh_msg_recv(from[0], b); 1969 close(from[0]); 1970 close(to[1]); 1971 if (r < 0) { 1972 error("%s: no reply", __func__); 1973 goto fail; 1974 } 1975 1976 errno = 0; 1977 while (waitpid(pid, &status, 0) == -1) { 1978 if (errno != EINTR) { 1979 error("%s: waitpid %ld: %s", 1980 __func__, (long)pid, strerror(errno)); 1981 goto fail; 1982 } 1983 } 1984 if (!WIFEXITED(status)) { 1985 error("%s: exited abnormally", __func__); 1986 goto fail; 1987 } 1988 if (WEXITSTATUS(status) != 0) { 1989 error("%s: exited with status %d", 1990 __func__, WEXITSTATUS(status)); 1991 goto fail; 1992 } 1993 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1994 error("%s: buffer error: %s", __func__, ssh_err(r)); 1995 goto fail; 1996 } 1997 if (rversion != version) { 1998 error("%s: bad version", __func__); 1999 goto fail; 2000 } 2001 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2002 error("%s: buffer error: %s", __func__, ssh_err(r)); 2003 fail: 2004 ssh_signal(SIGCHLD, osigchld); 2005 sshbuf_free(b); 2006 return -1; 2007 } 2008 ssh_signal(SIGCHLD, osigchld); 2009 sshbuf_free(b); 2010 2011 return 0; 2012 } 2013 2014 static int 2015 userauth_hostbased(struct ssh *ssh) 2016 { 2017 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2018 struct sshkey *private = NULL; 2019 struct sshbuf *b = NULL; 2020 u_char *sig = NULL, *keyblob = NULL; 2021 char *fp = NULL, *chost = NULL, *lname = NULL; 2022 size_t siglen = 0, keylen = 0; 2023 int i, r, success = 0; 2024 2025 if (authctxt->ktypes == NULL) { 2026 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2027 authctxt->ktypes = authctxt->oktypes; 2028 } 2029 2030 /* 2031 * Work through each listed type pattern in HostbasedKeyTypes, 2032 * trying each hostkey that matches the type in turn. 2033 */ 2034 for (;;) { 2035 if (authctxt->active_ktype == NULL) 2036 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2037 if (authctxt->active_ktype == NULL || 2038 *authctxt->active_ktype == '\0') 2039 break; 2040 debug3("%s: trying key type %s", __func__, 2041 authctxt->active_ktype); 2042 2043 /* check for a useful key */ 2044 private = NULL; 2045 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2046 if (authctxt->sensitive->keys[i] == NULL || 2047 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2048 continue; 2049 if (match_pattern_list( 2050 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2051 authctxt->active_ktype, 0) != 1) 2052 continue; 2053 /* we take and free the key */ 2054 private = authctxt->sensitive->keys[i]; 2055 authctxt->sensitive->keys[i] = NULL; 2056 break; 2057 } 2058 /* Found one */ 2059 if (private != NULL) 2060 break; 2061 /* No more keys of this type; advance */ 2062 authctxt->active_ktype = NULL; 2063 } 2064 if (private == NULL) { 2065 free(authctxt->oktypes); 2066 authctxt->oktypes = authctxt->ktypes = NULL; 2067 authctxt->active_ktype = NULL; 2068 debug("No more client hostkeys for hostbased authentication."); 2069 goto out; 2070 } 2071 2072 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2073 SSH_FP_DEFAULT)) == NULL) { 2074 error("%s: sshkey_fingerprint failed", __func__); 2075 goto out; 2076 } 2077 debug("%s: trying hostkey %s %s", 2078 __func__, sshkey_ssh_name(private), fp); 2079 2080 /* figure out a name for the client host */ 2081 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2082 if (lname == NULL) { 2083 error("%s: cannot get local ipaddr/name", __func__); 2084 goto out; 2085 } 2086 2087 /* XXX sshbuf_put_stringf? */ 2088 xasprintf(&chost, "%s.", lname); 2089 debug2("%s: chost %s", __func__, chost); 2090 2091 /* construct data */ 2092 if ((b = sshbuf_new()) == NULL) { 2093 error("%s: sshbuf_new failed", __func__); 2094 goto out; 2095 } 2096 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2097 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2098 goto out; 2099 } 2100 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2101 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2102 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2103 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2104 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2105 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2106 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2107 (r = sshbuf_put_cstring(b, chost)) != 0 || 2108 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2109 error("%s: buffer error: %s", __func__, ssh_err(r)); 2110 goto out; 2111 } 2112 2113 #ifdef DEBUG_PK 2114 sshbuf_dump(b, stderr); 2115 #endif 2116 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2117 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2118 error("sign using hostkey %s %s failed", 2119 sshkey_ssh_name(private), fp); 2120 goto out; 2121 } 2122 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2123 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2124 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2125 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2126 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2127 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2128 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2129 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2130 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2131 (r = sshpkt_send(ssh)) != 0) { 2132 error("%s: packet error: %s", __func__, ssh_err(r)); 2133 goto out; 2134 } 2135 success = 1; 2136 2137 out: 2138 if (sig != NULL) 2139 freezero(sig, siglen); 2140 free(keyblob); 2141 free(lname); 2142 free(fp); 2143 free(chost); 2144 sshkey_free(private); 2145 sshbuf_free(b); 2146 2147 return success; 2148 } 2149 2150 /* find auth method */ 2151 2152 /* 2153 * given auth method name, if configurable options permit this method fill 2154 * in auth_ident field and return true, otherwise return false. 2155 */ 2156 static int 2157 authmethod_is_enabled(Authmethod *method) 2158 { 2159 if (method == NULL) 2160 return 0; 2161 /* return false if options indicate this method is disabled */ 2162 if (method->enabled == NULL || *method->enabled == 0) 2163 return 0; 2164 /* return false if batch mode is enabled but method needs interactive mode */ 2165 if (method->batch_flag != NULL && *method->batch_flag != 0) 2166 return 0; 2167 return 1; 2168 } 2169 2170 static Authmethod * 2171 authmethod_lookup(const char *name) 2172 { 2173 Authmethod *method = NULL; 2174 if (name != NULL) 2175 for (method = authmethods; method->name != NULL; method++) 2176 if (strcmp(name, method->name) == 0) 2177 return method; 2178 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2179 return NULL; 2180 } 2181 2182 /* XXX internal state */ 2183 static Authmethod *current = NULL; 2184 static char *supported = NULL; 2185 static char *preferred = NULL; 2186 2187 /* 2188 * Given the authentication method list sent by the server, return the 2189 * next method we should try. If the server initially sends a nil list, 2190 * use a built-in default list. 2191 */ 2192 static Authmethod * 2193 authmethod_get(char *authlist) 2194 { 2195 char *name = NULL; 2196 u_int next; 2197 2198 /* Use a suitable default if we're passed a nil list. */ 2199 if (authlist == NULL || strlen(authlist) == 0) 2200 authlist = options.preferred_authentications; 2201 2202 if (supported == NULL || strcmp(authlist, supported) != 0) { 2203 debug3("start over, passed a different list %s", authlist); 2204 free(supported); 2205 supported = xstrdup(authlist); 2206 preferred = options.preferred_authentications; 2207 debug3("preferred %s", preferred); 2208 current = NULL; 2209 } else if (current != NULL && authmethod_is_enabled(current)) 2210 return current; 2211 2212 for (;;) { 2213 if ((name = match_list(preferred, supported, &next)) == NULL) { 2214 debug("No more authentication methods to try."); 2215 current = NULL; 2216 return NULL; 2217 } 2218 preferred += next; 2219 debug3("authmethod_lookup %s", name); 2220 debug3("remaining preferred: %s", preferred); 2221 if ((current = authmethod_lookup(name)) != NULL && 2222 authmethod_is_enabled(current)) { 2223 debug3("authmethod_is_enabled %s", name); 2224 debug("Next authentication method: %s", name); 2225 free(name); 2226 return current; 2227 } 2228 free(name); 2229 } 2230 } 2231 2232 static char * 2233 authmethods_get(void) 2234 { 2235 Authmethod *method = NULL; 2236 struct sshbuf *b; 2237 char *list; 2238 int r; 2239 2240 if ((b = sshbuf_new()) == NULL) 2241 fatal("%s: sshbuf_new failed", __func__); 2242 for (method = authmethods; method->name != NULL; method++) { 2243 if (authmethod_is_enabled(method)) { 2244 if ((r = sshbuf_putf(b, "%s%s", 2245 sshbuf_len(b) ? "," : "", method->name)) != 0) 2246 fatal("%s: buffer error: %s", 2247 __func__, ssh_err(r)); 2248 } 2249 } 2250 if ((list = sshbuf_dup_string(b)) == NULL) 2251 fatal("%s: sshbuf_dup_string failed", __func__); 2252 sshbuf_free(b); 2253 return list; 2254 } 2255