1 /* $OpenBSD: sshconnect2.c,v 1.323 2020/06/05 03:24:16 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 /* 134 * If we have a @cert-authority marker in known_hosts then 135 * prefer all certificate algorithms. 136 */ 137 if (sshkey_type_is_cert(ktype) && 138 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) { 139 ALG_APPEND(first, alg); 140 continue; 141 } 142 /* If the key appears in known_hosts then prefer it */ 143 if (lookup_key_in_hostkeys_by_type(hostkeys, 144 sshkey_type_plain(ktype), NULL)) { 145 ALG_APPEND(first, alg); 146 continue; 147 } 148 /* Otherwise, put it last */ 149 ALG_APPEND(last, alg); 150 } 151 #undef ALG_APPEND 152 xasprintf(&ret, "%s%s%s", first, 153 (*first == '\0' || *last == '\0') ? "" : ",", last); 154 if (*first != '\0') 155 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 156 157 free(first); 158 free(last); 159 free(hostname); 160 free(oavail); 161 free_hostkeys(hostkeys); 162 163 return ret; 164 } 165 166 void 167 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 168 { 169 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 170 char *s, *all_key; 171 int r, use_known_hosts_order = 0; 172 173 xxx_host = host; 174 xxx_hostaddr = hostaddr; 175 176 /* 177 * If the user has not specified HostkeyAlgorithms, or has only 178 * appended or removed algorithms from that list then prefer algorithms 179 * that are in the list that are supported by known_hosts keys. 180 */ 181 if (options.hostkeyalgorithms == NULL || 182 options.hostkeyalgorithms[0] == '-' || 183 options.hostkeyalgorithms[0] == '+') 184 use_known_hosts_order = 1; 185 186 /* Expand or fill in HostkeyAlgorithms */ 187 all_key = sshkey_alg_list(0, 0, 1, ','); 188 if (kex_assemble_names(&options.hostkeyalgorithms, 189 kex_default_pk_alg(), all_key) != 0) 190 fatal("%s: kex_assemble_namelist", __func__); 191 free(all_key); 192 193 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 194 fatal("%s: kex_names_cat", __func__); 195 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 196 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 197 compat_cipher_proposal(options.ciphers); 198 myproposal[PROPOSAL_ENC_ALGS_STOC] = 199 compat_cipher_proposal(options.ciphers); 200 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 201 myproposal[PROPOSAL_COMP_ALGS_STOC] = 202 (char *)compression_alg_list(options.compression); 203 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 204 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 205 if (use_known_hosts_order) { 206 /* Query known_hosts and prefer algorithms that appear there */ 207 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 208 compat_pkalg_proposal( 209 order_hostkeyalgs(host, hostaddr, port)); 210 } else { 211 /* Use specified HostkeyAlgorithms exactly */ 212 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 213 compat_pkalg_proposal(options.hostkeyalgorithms); 214 } 215 216 if (options.rekey_limit || options.rekey_interval) 217 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 218 options.rekey_interval); 219 220 /* start key exchange */ 221 if ((r = kex_setup(ssh, myproposal)) != 0) 222 fatal("kex_setup: %s", ssh_err(r)); 223 #ifdef WITH_OPENSSL 224 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 225 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 226 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 227 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 228 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 229 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 230 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 231 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 232 #endif 233 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 234 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 235 ssh->kex->verify_host_key=&verify_host_key_callback; 236 237 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 238 239 /* remove ext-info from the KEX proposals for rekeying */ 240 myproposal[PROPOSAL_KEX_ALGS] = 241 compat_kex_proposal(options.kex_algorithms); 242 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 243 fatal("kex_prop2buf: %s", ssh_err(r)); 244 245 session_id2 = ssh->kex->session_id; 246 session_id2_len = ssh->kex->session_id_len; 247 248 #ifdef DEBUG_KEXDH 249 /* send 1st encrypted/maced/compressed message */ 250 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 251 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 252 (r = sshpkt_send(ssh)) != 0 || 253 (r = ssh_packet_write_wait(ssh)) != 0) 254 fatal("%s: %s", __func__, ssh_err(r)); 255 #endif 256 } 257 258 /* 259 * Authenticate user 260 */ 261 262 typedef struct cauthctxt Authctxt; 263 typedef struct cauthmethod Authmethod; 264 typedef struct identity Identity; 265 typedef struct idlist Idlist; 266 267 struct identity { 268 TAILQ_ENTRY(identity) next; 269 int agent_fd; /* >=0 if agent supports key */ 270 struct sshkey *key; /* public/private key */ 271 char *filename; /* comment for agent-only keys */ 272 int tried; 273 int isprivate; /* key points to the private key */ 274 int userprovided; 275 }; 276 TAILQ_HEAD(idlist, identity); 277 278 struct cauthctxt { 279 const char *server_user; 280 const char *local_user; 281 const char *host; 282 const char *service; 283 struct cauthmethod *method; 284 sig_atomic_t success; 285 char *authlist; 286 #ifdef GSSAPI 287 /* gssapi */ 288 gss_OID_set gss_supported_mechs; 289 u_int mech_tried; 290 #endif 291 /* pubkey */ 292 struct idlist keys; 293 int agent_fd; 294 /* hostbased */ 295 Sensitive *sensitive; 296 char *oktypes, *ktypes; 297 const char *active_ktype; 298 /* kbd-interactive */ 299 int info_req_seen; 300 int attempt_kbdint; 301 /* password */ 302 int attempt_passwd; 303 /* generic */ 304 void *methoddata; 305 }; 306 307 struct cauthmethod { 308 char *name; /* string to compare against server's list */ 309 int (*userauth)(struct ssh *ssh); 310 void (*cleanup)(struct ssh *ssh); 311 int *enabled; /* flag in option struct that enables method */ 312 int *batch_flag; /* flag in option struct that disables method */ 313 }; 314 315 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 316 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 317 static int input_userauth_success(int, u_int32_t, struct ssh *); 318 static int input_userauth_failure(int, u_int32_t, struct ssh *); 319 static int input_userauth_banner(int, u_int32_t, struct ssh *); 320 static int input_userauth_error(int, u_int32_t, struct ssh *); 321 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 322 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 323 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 324 325 static int userauth_none(struct ssh *); 326 static int userauth_pubkey(struct ssh *); 327 static int userauth_passwd(struct ssh *); 328 static int userauth_kbdint(struct ssh *); 329 static int userauth_hostbased(struct ssh *); 330 331 #ifdef GSSAPI 332 static int userauth_gssapi(struct ssh *); 333 static void userauth_gssapi_cleanup(struct ssh *); 334 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 335 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 336 static int input_gssapi_error(int, u_int32_t, struct ssh *); 337 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 338 #endif 339 340 void userauth(struct ssh *, char *); 341 342 static void pubkey_cleanup(struct ssh *); 343 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 344 static void pubkey_prepare(Authctxt *); 345 static void pubkey_reset(Authctxt *); 346 static struct sshkey *load_identity_file(Identity *); 347 348 static Authmethod *authmethod_get(char *authlist); 349 static Authmethod *authmethod_lookup(const char *name); 350 static char *authmethods_get(void); 351 352 Authmethod authmethods[] = { 353 #ifdef GSSAPI 354 {"gssapi-with-mic", 355 userauth_gssapi, 356 userauth_gssapi_cleanup, 357 &options.gss_authentication, 358 NULL}, 359 #endif 360 {"hostbased", 361 userauth_hostbased, 362 NULL, 363 &options.hostbased_authentication, 364 NULL}, 365 {"publickey", 366 userauth_pubkey, 367 NULL, 368 &options.pubkey_authentication, 369 NULL}, 370 {"keyboard-interactive", 371 userauth_kbdint, 372 NULL, 373 &options.kbd_interactive_authentication, 374 &options.batch_mode}, 375 {"password", 376 userauth_passwd, 377 NULL, 378 &options.password_authentication, 379 &options.batch_mode}, 380 {"none", 381 userauth_none, 382 NULL, 383 NULL, 384 NULL}, 385 {NULL, NULL, NULL, NULL, NULL} 386 }; 387 388 void 389 ssh_userauth2(struct ssh *ssh, const char *local_user, 390 const char *server_user, char *host, Sensitive *sensitive) 391 { 392 Authctxt authctxt; 393 int r; 394 395 if (options.challenge_response_authentication) 396 options.kbd_interactive_authentication = 1; 397 if (options.preferred_authentications == NULL) 398 options.preferred_authentications = authmethods_get(); 399 400 /* setup authentication context */ 401 memset(&authctxt, 0, sizeof(authctxt)); 402 authctxt.server_user = server_user; 403 authctxt.local_user = local_user; 404 authctxt.host = host; 405 authctxt.service = "ssh-connection"; /* service name */ 406 authctxt.success = 0; 407 authctxt.method = authmethod_lookup("none"); 408 authctxt.authlist = NULL; 409 authctxt.methoddata = NULL; 410 authctxt.sensitive = sensitive; 411 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 412 authctxt.info_req_seen = 0; 413 authctxt.attempt_kbdint = 0; 414 authctxt.attempt_passwd = 0; 415 #if GSSAPI 416 authctxt.gss_supported_mechs = NULL; 417 authctxt.mech_tried = 0; 418 #endif 419 authctxt.agent_fd = -1; 420 pubkey_prepare(&authctxt); 421 if (authctxt.method == NULL) { 422 fatal("%s: internal error: cannot send userauth none request", 423 __func__); 424 } 425 426 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 427 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 428 (r = sshpkt_send(ssh)) != 0) 429 fatal("%s: %s", __func__, ssh_err(r)); 430 431 ssh->authctxt = &authctxt; 432 ssh_dispatch_init(ssh, &input_userauth_error); 433 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 434 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 435 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 436 pubkey_cleanup(ssh); 437 ssh->authctxt = NULL; 438 439 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 440 441 if (!authctxt.success) 442 fatal("Authentication failed."); 443 debug("Authentication succeeded (%s).", authctxt.method->name); 444 } 445 446 /* ARGSUSED */ 447 static int 448 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 449 { 450 int r; 451 452 if (ssh_packet_remaining(ssh) > 0) { 453 char *reply; 454 455 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 456 goto out; 457 debug2("service_accept: %s", reply); 458 free(reply); 459 } else { 460 debug2("buggy server: service_accept w/o service"); 461 } 462 if ((r = sshpkt_get_end(ssh)) != 0) 463 goto out; 464 debug("SSH2_MSG_SERVICE_ACCEPT received"); 465 466 /* initial userauth request */ 467 userauth_none(ssh); 468 469 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 470 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 471 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 472 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 473 r = 0; 474 out: 475 return r; 476 } 477 478 /* ARGSUSED */ 479 static int 480 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 481 { 482 return kex_input_ext_info(type, seqnr, ssh); 483 } 484 485 void 486 userauth(struct ssh *ssh, char *authlist) 487 { 488 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 489 490 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 491 authctxt->method->cleanup(ssh); 492 493 free(authctxt->methoddata); 494 authctxt->methoddata = NULL; 495 if (authlist == NULL) { 496 authlist = authctxt->authlist; 497 } else { 498 free(authctxt->authlist); 499 authctxt->authlist = authlist; 500 } 501 for (;;) { 502 Authmethod *method = authmethod_get(authlist); 503 if (method == NULL) 504 fatal("%s@%s: Permission denied (%s).", 505 authctxt->server_user, authctxt->host, authlist); 506 authctxt->method = method; 507 508 /* reset the per method handler */ 509 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 510 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 511 512 /* and try new method */ 513 if (method->userauth(ssh) != 0) { 514 debug2("we sent a %s packet, wait for reply", method->name); 515 break; 516 } else { 517 debug2("we did not send a packet, disable method"); 518 method->enabled = NULL; 519 } 520 } 521 } 522 523 /* ARGSUSED */ 524 static int 525 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 526 { 527 fatal("%s: bad message during authentication: type %d", __func__, type); 528 return 0; 529 } 530 531 /* ARGSUSED */ 532 static int 533 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 534 { 535 char *msg = NULL; 536 size_t len; 537 int r; 538 539 debug3("%s", __func__); 540 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 541 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 542 goto out; 543 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 544 fmprintf(stderr, "%s", msg); 545 r = 0; 546 out: 547 free(msg); 548 return r; 549 } 550 551 /* ARGSUSED */ 552 static int 553 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 554 { 555 Authctxt *authctxt = ssh->authctxt; 556 557 if (authctxt == NULL) 558 fatal("%s: no authentication context", __func__); 559 free(authctxt->authlist); 560 authctxt->authlist = NULL; 561 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 562 authctxt->method->cleanup(ssh); 563 free(authctxt->methoddata); 564 authctxt->methoddata = NULL; 565 authctxt->success = 1; /* break out */ 566 return 0; 567 } 568 569 #if 0 570 static int 571 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 572 { 573 Authctxt *authctxt = ssh->authctxt; 574 575 if (authctxt == NULL) 576 fatal("%s: no authentication context", __func__); 577 578 fatal("Unexpected authentication success during %s.", 579 authctxt->method->name); 580 return 0; 581 } 582 #endif 583 584 /* ARGSUSED */ 585 static int 586 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 587 { 588 Authctxt *authctxt = ssh->authctxt; 589 char *authlist = NULL; 590 u_char partial; 591 592 if (authctxt == NULL) 593 fatal("input_userauth_failure: no authentication context"); 594 595 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 || 596 sshpkt_get_u8(ssh, &partial) != 0 || 597 sshpkt_get_end(ssh) != 0) 598 goto out; 599 600 if (partial != 0) { 601 verbose("Authenticated with partial success."); 602 /* reset state */ 603 pubkey_reset(authctxt); 604 } 605 debug("Authentications that can continue: %s", authlist); 606 607 userauth(ssh, authlist); 608 authlist = NULL; 609 out: 610 free(authlist); 611 return 0; 612 } 613 614 /* 615 * Format an identity for logging including filename, key type, fingerprint 616 * and location (agent, etc.). Caller must free. 617 */ 618 static char * 619 format_identity(Identity *id) 620 { 621 char *fp = NULL, *ret = NULL; 622 const char *note = ""; 623 624 if (id->key != NULL) { 625 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 626 SSH_FP_DEFAULT); 627 } 628 if (id->key) { 629 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0) 630 note = " token"; 631 else if (sshkey_is_sk(id->key)) 632 note = " authenticator"; 633 } 634 xasprintf(&ret, "%s %s%s%s%s%s%s", 635 id->filename, 636 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 637 fp ? fp : "", 638 id->userprovided ? " explicit" : "", note, 639 id->agent_fd != -1 ? " agent" : ""); 640 free(fp); 641 return ret; 642 } 643 644 /* ARGSUSED */ 645 static int 646 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 647 { 648 Authctxt *authctxt = ssh->authctxt; 649 struct sshkey *key = NULL; 650 Identity *id = NULL; 651 int pktype, found = 0, sent = 0; 652 size_t blen; 653 char *pkalg = NULL, *fp = NULL, *ident = NULL; 654 u_char *pkblob = NULL; 655 int r; 656 657 if (authctxt == NULL) 658 fatal("input_userauth_pk_ok: no authentication context"); 659 660 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 661 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 662 (r = sshpkt_get_end(ssh)) != 0) 663 goto done; 664 665 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 666 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 667 goto done; 668 } 669 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 670 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 671 goto done; 672 } 673 if (key->type != pktype) { 674 error("input_userauth_pk_ok: type mismatch " 675 "for decoded key (received %d, expected %d)", 676 key->type, pktype); 677 goto done; 678 } 679 680 /* 681 * search keys in the reverse order, because last candidate has been 682 * moved to the end of the queue. this also avoids confusion by 683 * duplicate keys 684 */ 685 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 686 if (sshkey_equal(key, id->key)) { 687 found = 1; 688 break; 689 } 690 } 691 if (!found || id == NULL) { 692 fp = sshkey_fingerprint(key, options.fingerprint_hash, 693 SSH_FP_DEFAULT); 694 error("%s: server replied with unknown key: %s %s", __func__, 695 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 696 goto done; 697 } 698 ident = format_identity(id); 699 debug("Server accepts key: %s", ident); 700 sent = sign_and_send_pubkey(ssh, id); 701 r = 0; 702 done: 703 sshkey_free(key); 704 free(ident); 705 free(fp); 706 free(pkalg); 707 free(pkblob); 708 709 /* try another method if we did not send a packet */ 710 if (r == 0 && sent == 0) 711 userauth(ssh, NULL); 712 return r; 713 } 714 715 #ifdef GSSAPI 716 static int 717 userauth_gssapi(struct ssh *ssh) 718 { 719 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 720 Gssctxt *gssctxt = NULL; 721 OM_uint32 min; 722 int r, ok = 0; 723 gss_OID mech = NULL; 724 725 /* Try one GSSAPI method at a time, rather than sending them all at 726 * once. */ 727 728 if (authctxt->gss_supported_mechs == NULL) 729 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 730 731 /* Check to see whether the mechanism is usable before we offer it */ 732 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 733 !ok) { 734 mech = &authctxt->gss_supported_mechs-> 735 elements[authctxt->mech_tried]; 736 /* My DER encoding requires length<128 */ 737 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 738 mech, authctxt->host)) { 739 ok = 1; /* Mechanism works */ 740 } else { 741 authctxt->mech_tried++; 742 } 743 } 744 745 if (!ok || mech == NULL) 746 return 0; 747 748 authctxt->methoddata=(void *)gssctxt; 749 750 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 751 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 752 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 753 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 754 (r = sshpkt_put_u32(ssh, 1)) != 0 || 755 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 756 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 757 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 758 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 759 (r = sshpkt_send(ssh)) != 0) 760 fatal("%s: %s", __func__, ssh_err(r)); 761 762 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 763 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 764 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 765 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 766 767 authctxt->mech_tried++; /* Move along to next candidate */ 768 769 return 1; 770 } 771 772 static void 773 userauth_gssapi_cleanup(struct ssh *ssh) 774 { 775 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 776 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 777 778 ssh_gssapi_delete_ctx(&gssctxt); 779 authctxt->methoddata = NULL; 780 781 free(authctxt->gss_supported_mechs); 782 authctxt->gss_supported_mechs = NULL; 783 } 784 785 static OM_uint32 786 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 787 { 788 Authctxt *authctxt = ssh->authctxt; 789 Gssctxt *gssctxt = authctxt->methoddata; 790 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 791 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 792 gss_buffer_desc gssbuf; 793 OM_uint32 status, ms, flags; 794 int r; 795 796 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 797 recv_tok, &send_tok, &flags); 798 799 if (send_tok.length > 0) { 800 u_char type = GSS_ERROR(status) ? 801 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 802 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 803 804 if ((r = sshpkt_start(ssh, type)) != 0 || 805 (r = sshpkt_put_string(ssh, send_tok.value, 806 send_tok.length)) != 0 || 807 (r = sshpkt_send(ssh)) != 0) 808 fatal("%s: %s", __func__, ssh_err(r)); 809 810 gss_release_buffer(&ms, &send_tok); 811 } 812 813 if (status == GSS_S_COMPLETE) { 814 /* send either complete or MIC, depending on mechanism */ 815 if (!(flags & GSS_C_INTEG_FLAG)) { 816 if ((r = sshpkt_start(ssh, 817 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 818 (r = sshpkt_send(ssh)) != 0) 819 fatal("%s: %s", __func__, ssh_err(r)); 820 } else { 821 struct sshbuf *b; 822 823 if ((b = sshbuf_new()) == NULL) 824 fatal("%s: sshbuf_new failed", __func__); 825 ssh_gssapi_buildmic(b, authctxt->server_user, 826 authctxt->service, "gssapi-with-mic"); 827 828 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 829 fatal("%s: sshbuf_mutable_ptr failed", __func__); 830 gssbuf.length = sshbuf_len(b); 831 832 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 833 834 if (!GSS_ERROR(status)) { 835 if ((r = sshpkt_start(ssh, 836 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 837 (r = sshpkt_put_string(ssh, mic.value, 838 mic.length)) != 0 || 839 (r = sshpkt_send(ssh)) != 0) 840 fatal("%s: %s", __func__, ssh_err(r)); 841 } 842 843 sshbuf_free(b); 844 gss_release_buffer(&ms, &mic); 845 } 846 } 847 848 return status; 849 } 850 851 /* ARGSUSED */ 852 static int 853 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 854 { 855 Authctxt *authctxt = ssh->authctxt; 856 Gssctxt *gssctxt; 857 size_t oidlen; 858 u_char *oidv = NULL; 859 int r; 860 861 if (authctxt == NULL) 862 fatal("input_gssapi_response: no authentication context"); 863 gssctxt = authctxt->methoddata; 864 865 /* Setup our OID */ 866 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 867 goto done; 868 869 if (oidlen <= 2 || 870 oidv[0] != SSH_GSS_OIDTYPE || 871 oidv[1] != oidlen - 2) { 872 debug("Badly encoded mechanism OID received"); 873 userauth(ssh, NULL); 874 goto ok; 875 } 876 877 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 878 fatal("Server returned different OID than expected"); 879 880 if ((r = sshpkt_get_end(ssh)) != 0) 881 goto done; 882 883 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 884 /* Start again with next method on list */ 885 debug("Trying to start again"); 886 userauth(ssh, NULL); 887 goto ok; 888 } 889 ok: 890 r = 0; 891 done: 892 free(oidv); 893 return r; 894 } 895 896 /* ARGSUSED */ 897 static int 898 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 899 { 900 Authctxt *authctxt = ssh->authctxt; 901 gss_buffer_desc recv_tok; 902 u_char *p = NULL; 903 size_t len; 904 OM_uint32 status; 905 int r; 906 907 if (authctxt == NULL) 908 fatal("input_gssapi_response: no authentication context"); 909 910 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 911 (r = sshpkt_get_end(ssh)) != 0) 912 goto out; 913 914 recv_tok.value = p; 915 recv_tok.length = len; 916 status = process_gssapi_token(ssh, &recv_tok); 917 918 /* Start again with the next method in the list */ 919 if (GSS_ERROR(status)) { 920 userauth(ssh, NULL); 921 /* ok */ 922 } 923 r = 0; 924 out: 925 free(p); 926 return r; 927 } 928 929 /* ARGSUSED */ 930 static int 931 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 932 { 933 Authctxt *authctxt = ssh->authctxt; 934 Gssctxt *gssctxt; 935 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 936 gss_buffer_desc recv_tok; 937 OM_uint32 ms; 938 u_char *p = NULL; 939 size_t len; 940 int r; 941 942 if (authctxt == NULL) 943 fatal("input_gssapi_response: no authentication context"); 944 gssctxt = authctxt->methoddata; 945 946 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 947 (r = sshpkt_get_end(ssh)) != 0) { 948 free(p); 949 return r; 950 } 951 952 /* Stick it into GSSAPI and see what it says */ 953 recv_tok.value = p; 954 recv_tok.length = len; 955 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 956 &recv_tok, &send_tok, NULL); 957 free(p); 958 gss_release_buffer(&ms, &send_tok); 959 960 /* Server will be returning a failed packet after this one */ 961 return 0; 962 } 963 964 /* ARGSUSED */ 965 static int 966 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 967 { 968 char *msg = NULL; 969 char *lang = NULL; 970 int r; 971 972 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 973 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 974 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 975 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 976 goto out; 977 r = sshpkt_get_end(ssh); 978 debug("Server GSSAPI Error:\n%s", msg); 979 out: 980 free(msg); 981 free(lang); 982 return r; 983 } 984 #endif /* GSSAPI */ 985 986 static int 987 userauth_none(struct ssh *ssh) 988 { 989 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 990 int r; 991 992 /* initial userauth request */ 993 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 994 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 995 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 996 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 997 (r = sshpkt_send(ssh)) != 0) 998 fatal("%s: %s", __func__, ssh_err(r)); 999 return 1; 1000 } 1001 1002 static int 1003 userauth_passwd(struct ssh *ssh) 1004 { 1005 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1006 char *password, *prompt = NULL; 1007 const char *host = options.host_key_alias ? options.host_key_alias : 1008 authctxt->host; 1009 int r; 1010 1011 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 1012 return 0; 1013 1014 if (authctxt->attempt_passwd != 1) 1015 error("Permission denied, please try again."); 1016 1017 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 1018 password = read_passphrase(prompt, 0); 1019 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1020 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1021 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1022 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1023 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1024 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1025 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1026 (r = sshpkt_send(ssh)) != 0) 1027 fatal("%s: %s", __func__, ssh_err(r)); 1028 1029 free(prompt); 1030 if (password != NULL) 1031 freezero(password, strlen(password)); 1032 1033 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1034 &input_userauth_passwd_changereq); 1035 1036 return 1; 1037 } 1038 1039 /* 1040 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1041 */ 1042 /* ARGSUSED */ 1043 static int 1044 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1045 { 1046 Authctxt *authctxt = ssh->authctxt; 1047 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1048 char prompt[256]; 1049 const char *host; 1050 int r; 1051 1052 debug2("input_userauth_passwd_changereq"); 1053 1054 if (authctxt == NULL) 1055 fatal("input_userauth_passwd_changereq: " 1056 "no authentication context"); 1057 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1058 1059 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1060 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1061 goto out; 1062 if (strlen(info) > 0) 1063 logit("%s", info); 1064 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1065 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1066 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1067 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1068 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1069 goto out; 1070 1071 snprintf(prompt, sizeof(prompt), 1072 "Enter %.30s@%.128s's old password: ", 1073 authctxt->server_user, host); 1074 password = read_passphrase(prompt, 0); 1075 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1076 goto out; 1077 1078 freezero(password, strlen(password)); 1079 password = NULL; 1080 while (password == NULL) { 1081 snprintf(prompt, sizeof(prompt), 1082 "Enter %.30s@%.128s's new password: ", 1083 authctxt->server_user, host); 1084 password = read_passphrase(prompt, RP_ALLOW_EOF); 1085 if (password == NULL) { 1086 /* bail out */ 1087 r = 0; 1088 goto out; 1089 } 1090 snprintf(prompt, sizeof(prompt), 1091 "Retype %.30s@%.128s's new password: ", 1092 authctxt->server_user, host); 1093 retype = read_passphrase(prompt, 0); 1094 if (strcmp(password, retype) != 0) { 1095 freezero(password, strlen(password)); 1096 logit("Mismatch; try again, EOF to quit."); 1097 password = NULL; 1098 } 1099 freezero(retype, strlen(retype)); 1100 } 1101 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1102 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1103 (r = sshpkt_send(ssh)) != 0) 1104 goto out; 1105 1106 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1107 &input_userauth_passwd_changereq); 1108 r = 0; 1109 out: 1110 if (password) 1111 freezero(password, strlen(password)); 1112 free(info); 1113 free(lang); 1114 return r; 1115 } 1116 1117 /* 1118 * Select an algorithm for publickey signatures. 1119 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1120 * 1121 * Call with ssh==NULL to ignore server-sig-algs extension list and 1122 * only attempt with the key's base signature type. 1123 */ 1124 static char * 1125 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1126 { 1127 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1128 1129 /* 1130 * The signature algorithm will only differ from the key algorithm 1131 * for RSA keys/certs and when the server advertises support for 1132 * newer (SHA2) algorithms. 1133 */ 1134 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1135 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1136 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1137 /* Filter base key signature alg against our configuration */ 1138 return match_list(sshkey_ssh_name(key), 1139 options.pubkey_key_types, NULL); 1140 } 1141 1142 /* 1143 * For RSA keys/certs, since these might have a different sig type: 1144 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1145 * that also appears in the supported signature algorithms list from 1146 * the server. 1147 */ 1148 oallowed = allowed = xstrdup(options.pubkey_key_types); 1149 while ((cp = strsep(&allowed, ",")) != NULL) { 1150 if (sshkey_type_from_name(cp) != key->type) 1151 continue; 1152 tmp = match_list(sshkey_sigalg_by_name(cp), 1153 ssh->kex->server_sig_algs, NULL); 1154 if (tmp != NULL) 1155 alg = xstrdup(cp); 1156 free(tmp); 1157 if (alg != NULL) 1158 break; 1159 } 1160 free(oallowed); 1161 return alg; 1162 } 1163 1164 static int 1165 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1166 const u_char *data, size_t datalen, u_int compat, const char *alg) 1167 { 1168 struct sshkey *sign_key = NULL, *prv = NULL; 1169 int r = SSH_ERR_INTERNAL_ERROR; 1170 struct notifier_ctx *notifier = NULL; 1171 char *fp = NULL; 1172 1173 *sigp = NULL; 1174 *lenp = 0; 1175 1176 /* The agent supports this key. */ 1177 if (id->key != NULL && id->agent_fd != -1) { 1178 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1179 data, datalen, alg, compat); 1180 } 1181 1182 /* 1183 * We have already loaded the private key or the private key is 1184 * stored in external hardware. 1185 */ 1186 if (id->key != NULL && 1187 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1188 sign_key = id->key; 1189 } else { 1190 /* Load the private key from the file. */ 1191 if ((prv = load_identity_file(id)) == NULL) 1192 return SSH_ERR_KEY_NOT_FOUND; 1193 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1194 error("%s: private key %s contents do not match public", 1195 __func__, id->filename); 1196 r = SSH_ERR_KEY_NOT_FOUND; 1197 goto out; 1198 } 1199 sign_key = prv; 1200 if (sshkey_is_sk(sign_key) && 1201 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 1202 /* XXX match batch mode should just skip these keys? */ 1203 if ((fp = sshkey_fingerprint(sign_key, 1204 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) 1205 fatal("%s: sshkey_fingerprint", __func__); 1206 notifier = notify_start(options.batch_mode, 1207 "Confirm user presence for key %s %s", 1208 sshkey_type(sign_key), fp); 1209 free(fp); 1210 } 1211 } 1212 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen, 1213 alg, options.sk_provider, compat)) != 0) { 1214 debug("%s: sshkey_sign: %s", __func__, ssh_err(r)); 1215 goto out; 1216 } 1217 /* 1218 * PKCS#11 tokens may not support all signature algorithms, 1219 * so check what we get back. 1220 */ 1221 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) { 1222 debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r)); 1223 goto out; 1224 } 1225 /* success */ 1226 r = 0; 1227 out: 1228 notify_complete(notifier); 1229 sshkey_free(prv); 1230 return r; 1231 } 1232 1233 static int 1234 id_filename_matches(Identity *id, Identity *private_id) 1235 { 1236 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1237 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1238 size_t i, slen; 1239 1240 if (strcmp(id->filename, private_id->filename) == 0) 1241 return 1; 1242 for (i = 0; suffixes[i]; i++) { 1243 slen = strlen(suffixes[i]); 1244 if (len > slen && plen == len - slen && 1245 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1246 memcmp(id->filename, private_id->filename, plen) == 0) 1247 return 1; 1248 } 1249 return 0; 1250 } 1251 1252 static int 1253 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1254 { 1255 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1256 struct sshbuf *b = NULL; 1257 Identity *private_id, *sign_id = NULL; 1258 u_char *signature = NULL; 1259 size_t slen = 0, skip = 0; 1260 int r, fallback_sigtype, sent = 0; 1261 char *alg = NULL, *fp = NULL; 1262 const char *loc = ""; 1263 1264 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1265 SSH_FP_DEFAULT)) == NULL) 1266 return 0; 1267 1268 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1269 1270 /* 1271 * If the key is an certificate, try to find a matching private key 1272 * and use it to complete the signature. 1273 * If no such private key exists, fall back to trying the certificate 1274 * key itself in case it has a private half already loaded. 1275 * This will try to set sign_id to the private key that will perform 1276 * the signature. 1277 */ 1278 if (sshkey_is_cert(id->key)) { 1279 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1280 if (sshkey_equal_public(id->key, private_id->key) && 1281 id->key->type != private_id->key->type) { 1282 sign_id = private_id; 1283 break; 1284 } 1285 } 1286 /* 1287 * Exact key matches are preferred, but also allow 1288 * filename matches for non-PKCS#11/agent keys that 1289 * didn't load public keys. This supports the case 1290 * of keeping just a private key file and public 1291 * certificate on disk. 1292 */ 1293 if (sign_id == NULL && 1294 !id->isprivate && id->agent_fd == -1 && 1295 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1296 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1297 if (private_id->key == NULL && 1298 id_filename_matches(id, private_id)) { 1299 sign_id = private_id; 1300 break; 1301 } 1302 } 1303 } 1304 if (sign_id != NULL) { 1305 debug2("%s: using private key \"%s\"%s for " 1306 "certificate", __func__, id->filename, 1307 id->agent_fd != -1 ? " from agent" : ""); 1308 } else { 1309 debug("%s: no separate private key for certificate " 1310 "\"%s\"", __func__, id->filename); 1311 } 1312 } 1313 1314 /* 1315 * If the above didn't select another identity to do the signing 1316 * then default to the one we started with. 1317 */ 1318 if (sign_id == NULL) 1319 sign_id = id; 1320 1321 /* assemble and sign data */ 1322 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1323 free(alg); 1324 slen = 0; 1325 signature = NULL; 1326 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1327 id->key)) == NULL) { 1328 error("%s: no mutual signature supported", __func__); 1329 goto out; 1330 } 1331 debug3("%s: signing using %s %s", __func__, alg, fp); 1332 1333 sshbuf_free(b); 1334 if ((b = sshbuf_new()) == NULL) 1335 fatal("%s: sshbuf_new failed", __func__); 1336 if (datafellows & SSH_OLD_SESSIONID) { 1337 if ((r = sshbuf_put(b, session_id2, 1338 session_id2_len)) != 0) { 1339 fatal("%s: sshbuf_put: %s", 1340 __func__, ssh_err(r)); 1341 } 1342 } else { 1343 if ((r = sshbuf_put_string(b, session_id2, 1344 session_id2_len)) != 0) { 1345 fatal("%s: sshbuf_put_string: %s", 1346 __func__, ssh_err(r)); 1347 } 1348 } 1349 skip = sshbuf_len(b); 1350 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1351 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1352 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1353 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1354 (r = sshbuf_put_u8(b, 1)) != 0 || 1355 (r = sshbuf_put_cstring(b, alg)) != 0 || 1356 (r = sshkey_puts(id->key, b)) != 0) { 1357 fatal("%s: assemble signed data: %s", 1358 __func__, ssh_err(r)); 1359 } 1360 1361 /* generate signature */ 1362 r = identity_sign(sign_id, &signature, &slen, 1363 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1364 if (r == 0) 1365 break; 1366 else if (r == SSH_ERR_KEY_NOT_FOUND) 1367 goto out; /* soft failure */ 1368 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1369 !fallback_sigtype) { 1370 if (sign_id->agent_fd != -1) 1371 loc = "agent "; 1372 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1373 loc = "token "; 1374 logit("%skey %s %s returned incorrect signature type", 1375 loc, sshkey_type(id->key), fp); 1376 continue; 1377 } 1378 error("%s: signing failed for %s \"%s\"%s: %s", __func__, 1379 sshkey_type(sign_id->key), sign_id->filename, 1380 id->agent_fd != -1 ? " from agent" : "", ssh_err(r)); 1381 goto out; 1382 } 1383 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1384 fatal("%s: no signature", __func__); 1385 1386 /* append signature */ 1387 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1388 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1389 1390 #ifdef DEBUG_PK 1391 sshbuf_dump(b, stderr); 1392 #endif 1393 /* skip session id and packet type */ 1394 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1395 fatal("%s: consume: %s", __func__, ssh_err(r)); 1396 1397 /* put remaining data from buffer into packet */ 1398 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1399 (r = sshpkt_putb(ssh, b)) != 0 || 1400 (r = sshpkt_send(ssh)) != 0) 1401 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1402 1403 /* success */ 1404 sent = 1; 1405 1406 out: 1407 free(fp); 1408 free(alg); 1409 sshbuf_free(b); 1410 freezero(signature, slen); 1411 return sent; 1412 } 1413 1414 static int 1415 send_pubkey_test(struct ssh *ssh, Identity *id) 1416 { 1417 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1418 u_char *blob = NULL; 1419 char *alg = NULL; 1420 size_t bloblen; 1421 u_int have_sig = 0; 1422 int sent = 0, r; 1423 1424 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1425 debug("%s: no mutual signature algorithm", __func__); 1426 goto out; 1427 } 1428 1429 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1430 /* we cannot handle this key */ 1431 debug3("%s: cannot handle key", __func__); 1432 goto out; 1433 } 1434 /* register callback for USERAUTH_PK_OK message */ 1435 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1436 1437 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1438 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1439 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1440 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1441 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1442 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1443 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1444 (r = sshpkt_send(ssh)) != 0) 1445 fatal("%s: %s", __func__, ssh_err(r)); 1446 sent = 1; 1447 1448 out: 1449 free(alg); 1450 free(blob); 1451 return sent; 1452 } 1453 1454 static struct sshkey * 1455 load_identity_file(Identity *id) 1456 { 1457 struct sshkey *private = NULL; 1458 char prompt[300], *passphrase, *comment; 1459 int r, quit = 0, i; 1460 struct stat st; 1461 1462 if (stat(id->filename, &st) == -1) { 1463 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1464 id->filename, strerror(errno)); 1465 return NULL; 1466 } 1467 snprintf(prompt, sizeof prompt, 1468 "Enter passphrase for key '%.100s': ", id->filename); 1469 for (i = 0; i <= options.number_of_password_prompts; i++) { 1470 if (i == 0) 1471 passphrase = ""; 1472 else { 1473 passphrase = read_passphrase(prompt, 0); 1474 if (*passphrase == '\0') { 1475 debug2("no passphrase given, try next key"); 1476 free(passphrase); 1477 break; 1478 } 1479 } 1480 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1481 passphrase, &private, &comment))) { 1482 case 0: 1483 break; 1484 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1485 if (options.batch_mode) { 1486 quit = 1; 1487 break; 1488 } 1489 if (i != 0) 1490 debug2("bad passphrase given, try again..."); 1491 break; 1492 case SSH_ERR_SYSTEM_ERROR: 1493 if (errno == ENOENT) { 1494 debug2("Load key \"%s\": %s", 1495 id->filename, ssh_err(r)); 1496 quit = 1; 1497 break; 1498 } 1499 /* FALLTHROUGH */ 1500 default: 1501 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1502 quit = 1; 1503 break; 1504 } 1505 if (private != NULL && sshkey_is_sk(private) && 1506 options.sk_provider == NULL) { 1507 debug("key \"%s\" is an authenticator-hosted key, " 1508 "but no provider specified", id->filename); 1509 sshkey_free(private); 1510 private = NULL; 1511 quit = 1; 1512 } 1513 if (!quit && private != NULL && id->agent_fd == -1 && 1514 !(id->key && id->isprivate)) 1515 maybe_add_key_to_agent(id->filename, private, comment, 1516 passphrase); 1517 if (i > 0) 1518 freezero(passphrase, strlen(passphrase)); 1519 free(comment); 1520 if (private != NULL || quit) 1521 break; 1522 } 1523 return private; 1524 } 1525 1526 static int 1527 key_type_allowed_by_config(struct sshkey *key) 1528 { 1529 if (match_pattern_list(sshkey_ssh_name(key), 1530 options.pubkey_key_types, 0) == 1) 1531 return 1; 1532 1533 /* RSA keys/certs might be allowed by alternate signature types */ 1534 switch (key->type) { 1535 case KEY_RSA: 1536 if (match_pattern_list("rsa-sha2-512", 1537 options.pubkey_key_types, 0) == 1) 1538 return 1; 1539 if (match_pattern_list("rsa-sha2-256", 1540 options.pubkey_key_types, 0) == 1) 1541 return 1; 1542 break; 1543 case KEY_RSA_CERT: 1544 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1545 options.pubkey_key_types, 0) == 1) 1546 return 1; 1547 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1548 options.pubkey_key_types, 0) == 1) 1549 return 1; 1550 break; 1551 } 1552 return 0; 1553 } 1554 1555 1556 /* 1557 * try keys in the following order: 1558 * 1. certificates listed in the config file 1559 * 2. other input certificates 1560 * 3. agent keys that are found in the config file 1561 * 4. other agent keys 1562 * 5. keys that are only listed in the config file 1563 */ 1564 static void 1565 pubkey_prepare(Authctxt *authctxt) 1566 { 1567 struct identity *id, *id2, *tmp; 1568 struct idlist agent, files, *preferred; 1569 struct sshkey *key; 1570 int agent_fd = -1, i, r, found; 1571 size_t j; 1572 struct ssh_identitylist *idlist; 1573 char *ident; 1574 1575 TAILQ_INIT(&agent); /* keys from the agent */ 1576 TAILQ_INIT(&files); /* keys from the config file */ 1577 preferred = &authctxt->keys; 1578 TAILQ_INIT(preferred); /* preferred order of keys */ 1579 1580 /* list of keys stored in the filesystem and PKCS#11 */ 1581 for (i = 0; i < options.num_identity_files; i++) { 1582 key = options.identity_keys[i]; 1583 if (key && key->cert && 1584 key->cert->type != SSH2_CERT_TYPE_USER) { 1585 debug("%s: ignoring certificate %s: not a user " 1586 "certificate", __func__, 1587 options.identity_files[i]); 1588 continue; 1589 } 1590 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1591 debug("%s: ignoring authenticator-hosted key %s as no " 1592 "SecurityKeyProvider has been specified", 1593 __func__, options.identity_files[i]); 1594 continue; 1595 } 1596 options.identity_keys[i] = NULL; 1597 id = xcalloc(1, sizeof(*id)); 1598 id->agent_fd = -1; 1599 id->key = key; 1600 id->filename = xstrdup(options.identity_files[i]); 1601 id->userprovided = options.identity_file_userprovided[i]; 1602 TAILQ_INSERT_TAIL(&files, id, next); 1603 } 1604 /* list of certificates specified by user */ 1605 for (i = 0; i < options.num_certificate_files; i++) { 1606 key = options.certificates[i]; 1607 if (!sshkey_is_cert(key) || key->cert == NULL || 1608 key->cert->type != SSH2_CERT_TYPE_USER) { 1609 debug("%s: ignoring certificate %s: not a user " 1610 "certificate", __func__, 1611 options.identity_files[i]); 1612 continue; 1613 } 1614 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { 1615 debug("%s: ignoring authenticator-hosted key " 1616 "certificate %s as no " 1617 "SecurityKeyProvider has been specified", 1618 __func__, options.identity_files[i]); 1619 continue; 1620 } 1621 id = xcalloc(1, sizeof(*id)); 1622 id->agent_fd = -1; 1623 id->key = key; 1624 id->filename = xstrdup(options.certificate_files[i]); 1625 id->userprovided = options.certificate_file_userprovided[i]; 1626 TAILQ_INSERT_TAIL(preferred, id, next); 1627 } 1628 /* list of keys supported by the agent */ 1629 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1630 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1631 debug("%s: ssh_get_authentication_socket: %s", 1632 __func__, ssh_err(r)); 1633 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1634 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1635 debug("%s: ssh_fetch_identitylist: %s", 1636 __func__, ssh_err(r)); 1637 close(agent_fd); 1638 } else { 1639 for (j = 0; j < idlist->nkeys; j++) { 1640 found = 0; 1641 TAILQ_FOREACH(id, &files, next) { 1642 /* 1643 * agent keys from the config file are 1644 * preferred 1645 */ 1646 if (sshkey_equal(idlist->keys[j], id->key)) { 1647 TAILQ_REMOVE(&files, id, next); 1648 TAILQ_INSERT_TAIL(preferred, id, next); 1649 id->agent_fd = agent_fd; 1650 found = 1; 1651 break; 1652 } 1653 } 1654 if (!found && !options.identities_only) { 1655 id = xcalloc(1, sizeof(*id)); 1656 /* XXX "steals" key/comment from idlist */ 1657 id->key = idlist->keys[j]; 1658 id->filename = idlist->comments[j]; 1659 idlist->keys[j] = NULL; 1660 idlist->comments[j] = NULL; 1661 id->agent_fd = agent_fd; 1662 TAILQ_INSERT_TAIL(&agent, id, next); 1663 } 1664 } 1665 ssh_free_identitylist(idlist); 1666 /* append remaining agent keys */ 1667 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1668 TAILQ_REMOVE(&agent, id, next); 1669 TAILQ_INSERT_TAIL(preferred, id, next); 1670 } 1671 authctxt->agent_fd = agent_fd; 1672 } 1673 /* Prefer PKCS11 keys that are explicitly listed */ 1674 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1675 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1676 continue; 1677 found = 0; 1678 TAILQ_FOREACH(id2, &files, next) { 1679 if (id2->key == NULL || 1680 (id2->key->flags & SSHKEY_FLAG_EXT) != 0) 1681 continue; 1682 if (sshkey_equal(id->key, id2->key)) { 1683 TAILQ_REMOVE(&files, id, next); 1684 TAILQ_INSERT_TAIL(preferred, id, next); 1685 found = 1; 1686 break; 1687 } 1688 } 1689 /* If IdentitiesOnly set and key not found then don't use it */ 1690 if (!found && options.identities_only) { 1691 TAILQ_REMOVE(&files, id, next); 1692 freezero(id, sizeof(*id)); 1693 } 1694 } 1695 /* append remaining keys from the config file */ 1696 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1697 TAILQ_REMOVE(&files, id, next); 1698 TAILQ_INSERT_TAIL(preferred, id, next); 1699 } 1700 /* finally, filter by PubkeyAcceptedKeyTypes */ 1701 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1702 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1703 debug("Skipping %s key %s - " 1704 "not in PubkeyAcceptedKeyTypes", 1705 sshkey_ssh_name(id->key), id->filename); 1706 TAILQ_REMOVE(preferred, id, next); 1707 sshkey_free(id->key); 1708 free(id->filename); 1709 memset(id, 0, sizeof(*id)); 1710 continue; 1711 } 1712 } 1713 /* List the keys we plan on using */ 1714 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1715 ident = format_identity(id); 1716 debug("Will attempt key: %s", ident); 1717 free(ident); 1718 } 1719 debug2("%s: done", __func__); 1720 } 1721 1722 static void 1723 pubkey_cleanup(struct ssh *ssh) 1724 { 1725 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1726 Identity *id; 1727 1728 if (authctxt->agent_fd != -1) { 1729 ssh_close_authentication_socket(authctxt->agent_fd); 1730 authctxt->agent_fd = -1; 1731 } 1732 for (id = TAILQ_FIRST(&authctxt->keys); id; 1733 id = TAILQ_FIRST(&authctxt->keys)) { 1734 TAILQ_REMOVE(&authctxt->keys, id, next); 1735 sshkey_free(id->key); 1736 free(id->filename); 1737 free(id); 1738 } 1739 } 1740 1741 static void 1742 pubkey_reset(Authctxt *authctxt) 1743 { 1744 Identity *id; 1745 1746 TAILQ_FOREACH(id, &authctxt->keys, next) 1747 id->tried = 0; 1748 } 1749 1750 static int 1751 try_identity(Identity *id) 1752 { 1753 if (!id->key) 1754 return (0); 1755 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1756 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1757 debug("Skipped %s key %s for RSA/MD5 server", 1758 sshkey_type(id->key), id->filename); 1759 return (0); 1760 } 1761 return 1; 1762 } 1763 1764 static int 1765 userauth_pubkey(struct ssh *ssh) 1766 { 1767 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1768 Identity *id; 1769 int sent = 0; 1770 char *ident; 1771 1772 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1773 if (id->tried++) 1774 return (0); 1775 /* move key to the end of the queue */ 1776 TAILQ_REMOVE(&authctxt->keys, id, next); 1777 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1778 /* 1779 * send a test message if we have the public key. for 1780 * encrypted keys we cannot do this and have to load the 1781 * private key instead 1782 */ 1783 if (id->key != NULL) { 1784 if (try_identity(id)) { 1785 ident = format_identity(id); 1786 debug("Offering public key: %s", ident); 1787 free(ident); 1788 sent = send_pubkey_test(ssh, id); 1789 } 1790 } else { 1791 debug("Trying private key: %s", id->filename); 1792 id->key = load_identity_file(id); 1793 if (id->key != NULL) { 1794 if (try_identity(id)) { 1795 id->isprivate = 1; 1796 sent = sign_and_send_pubkey(ssh, id); 1797 } 1798 sshkey_free(id->key); 1799 id->key = NULL; 1800 id->isprivate = 0; 1801 } 1802 } 1803 if (sent) 1804 return (sent); 1805 } 1806 return (0); 1807 } 1808 1809 /* 1810 * Send userauth request message specifying keyboard-interactive method. 1811 */ 1812 static int 1813 userauth_kbdint(struct ssh *ssh) 1814 { 1815 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1816 int r; 1817 1818 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1819 return 0; 1820 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1821 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1822 debug3("userauth_kbdint: disable: no info_req_seen"); 1823 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1824 return 0; 1825 } 1826 1827 debug2("userauth_kbdint"); 1828 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1829 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1830 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1831 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1832 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1833 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1834 options.kbd_interactive_devices : "")) != 0 || 1835 (r = sshpkt_send(ssh)) != 0) 1836 fatal("%s: %s", __func__, ssh_err(r)); 1837 1838 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1839 return 1; 1840 } 1841 1842 /* 1843 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1844 */ 1845 static int 1846 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1847 { 1848 Authctxt *authctxt = ssh->authctxt; 1849 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1850 char *response = NULL; 1851 u_char echo = 0; 1852 u_int num_prompts, i; 1853 int r; 1854 1855 debug2("input_userauth_info_req"); 1856 1857 if (authctxt == NULL) 1858 fatal("input_userauth_info_req: no authentication context"); 1859 1860 authctxt->info_req_seen = 1; 1861 1862 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1863 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1864 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1865 goto out; 1866 if (strlen(name) > 0) 1867 logit("%s", name); 1868 if (strlen(inst) > 0) 1869 logit("%s", inst); 1870 1871 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1872 goto out; 1873 /* 1874 * Begin to build info response packet based on prompts requested. 1875 * We commit to providing the correct number of responses, so if 1876 * further on we run into a problem that prevents this, we have to 1877 * be sure and clean this up and send a correct error response. 1878 */ 1879 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1880 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1881 goto out; 1882 1883 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1884 for (i = 0; i < num_prompts; i++) { 1885 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1886 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1887 goto out; 1888 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1889 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1890 goto out; 1891 freezero(response, strlen(response)); 1892 free(prompt); 1893 response = prompt = NULL; 1894 } 1895 /* done with parsing incoming message. */ 1896 if ((r = sshpkt_get_end(ssh)) != 0 || 1897 (r = sshpkt_add_padding(ssh, 64)) != 0) 1898 goto out; 1899 r = sshpkt_send(ssh); 1900 out: 1901 if (response) 1902 freezero(response, strlen(response)); 1903 free(prompt); 1904 free(name); 1905 free(inst); 1906 free(lang); 1907 return r; 1908 } 1909 1910 static int 1911 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1912 const u_char *data, size_t datalen) 1913 { 1914 struct sshbuf *b; 1915 struct stat st; 1916 pid_t pid; 1917 int r, to[2], from[2], status; 1918 int sock = ssh_packet_get_connection_in(ssh); 1919 u_char rversion = 0, version = 2; 1920 void (*osigchld)(int); 1921 1922 *sigp = NULL; 1923 *lenp = 0; 1924 1925 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) { 1926 error("%s: not installed: %s", __func__, strerror(errno)); 1927 return -1; 1928 } 1929 if (fflush(stdout) != 0) { 1930 error("%s: fflush: %s", __func__, strerror(errno)); 1931 return -1; 1932 } 1933 if (pipe(to) == -1) { 1934 error("%s: pipe: %s", __func__, strerror(errno)); 1935 return -1; 1936 } 1937 if (pipe(from) == -1) { 1938 error("%s: pipe: %s", __func__, strerror(errno)); 1939 return -1; 1940 } 1941 if ((pid = fork()) == -1) { 1942 error("%s: fork: %s", __func__, strerror(errno)); 1943 return -1; 1944 } 1945 osigchld = ssh_signal(SIGCHLD, SIG_DFL); 1946 if (pid == 0) { 1947 close(from[0]); 1948 if (dup2(from[1], STDOUT_FILENO) == -1) 1949 fatal("%s: dup2: %s", __func__, strerror(errno)); 1950 close(to[1]); 1951 if (dup2(to[0], STDIN_FILENO) == -1) 1952 fatal("%s: dup2: %s", __func__, strerror(errno)); 1953 close(from[1]); 1954 close(to[0]); 1955 1956 if (dup2(sock, STDERR_FILENO + 1) == -1) 1957 fatal("%s: dup2: %s", __func__, strerror(errno)); 1958 sock = STDERR_FILENO + 1; 1959 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 1960 closefrom(sock + 1); 1961 1962 debug3("%s: [child] pid=%ld, exec %s", 1963 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1964 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1965 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1966 strerror(errno)); 1967 } 1968 close(from[1]); 1969 close(to[0]); 1970 sock = STDERR_FILENO + 1; 1971 1972 if ((b = sshbuf_new()) == NULL) 1973 fatal("%s: sshbuf_new failed", __func__); 1974 /* send # of sock, data to be signed */ 1975 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1976 (r = sshbuf_put_string(b, data, datalen)) != 0) 1977 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1978 if (ssh_msg_send(to[1], version, b) == -1) 1979 fatal("%s: couldn't send request", __func__); 1980 sshbuf_reset(b); 1981 r = ssh_msg_recv(from[0], b); 1982 close(from[0]); 1983 close(to[1]); 1984 if (r < 0) { 1985 error("%s: no reply", __func__); 1986 goto fail; 1987 } 1988 1989 errno = 0; 1990 while (waitpid(pid, &status, 0) == -1) { 1991 if (errno != EINTR) { 1992 error("%s: waitpid %ld: %s", 1993 __func__, (long)pid, strerror(errno)); 1994 goto fail; 1995 } 1996 } 1997 if (!WIFEXITED(status)) { 1998 error("%s: exited abnormally", __func__); 1999 goto fail; 2000 } 2001 if (WEXITSTATUS(status) != 0) { 2002 error("%s: exited with status %d", 2003 __func__, WEXITSTATUS(status)); 2004 goto fail; 2005 } 2006 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 2007 error("%s: buffer error: %s", __func__, ssh_err(r)); 2008 goto fail; 2009 } 2010 if (rversion != version) { 2011 error("%s: bad version", __func__); 2012 goto fail; 2013 } 2014 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 2015 error("%s: buffer error: %s", __func__, ssh_err(r)); 2016 fail: 2017 ssh_signal(SIGCHLD, osigchld); 2018 sshbuf_free(b); 2019 return -1; 2020 } 2021 ssh_signal(SIGCHLD, osigchld); 2022 sshbuf_free(b); 2023 2024 return 0; 2025 } 2026 2027 static int 2028 userauth_hostbased(struct ssh *ssh) 2029 { 2030 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 2031 struct sshkey *private = NULL; 2032 struct sshbuf *b = NULL; 2033 u_char *sig = NULL, *keyblob = NULL; 2034 char *fp = NULL, *chost = NULL, *lname = NULL; 2035 size_t siglen = 0, keylen = 0; 2036 int i, r, success = 0; 2037 2038 if (authctxt->ktypes == NULL) { 2039 authctxt->oktypes = xstrdup(options.hostbased_key_types); 2040 authctxt->ktypes = authctxt->oktypes; 2041 } 2042 2043 /* 2044 * Work through each listed type pattern in HostbasedKeyTypes, 2045 * trying each hostkey that matches the type in turn. 2046 */ 2047 for (;;) { 2048 if (authctxt->active_ktype == NULL) 2049 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 2050 if (authctxt->active_ktype == NULL || 2051 *authctxt->active_ktype == '\0') 2052 break; 2053 debug3("%s: trying key type %s", __func__, 2054 authctxt->active_ktype); 2055 2056 /* check for a useful key */ 2057 private = NULL; 2058 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 2059 if (authctxt->sensitive->keys[i] == NULL || 2060 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 2061 continue; 2062 if (match_pattern_list( 2063 sshkey_ssh_name(authctxt->sensitive->keys[i]), 2064 authctxt->active_ktype, 0) != 1) 2065 continue; 2066 /* we take and free the key */ 2067 private = authctxt->sensitive->keys[i]; 2068 authctxt->sensitive->keys[i] = NULL; 2069 break; 2070 } 2071 /* Found one */ 2072 if (private != NULL) 2073 break; 2074 /* No more keys of this type; advance */ 2075 authctxt->active_ktype = NULL; 2076 } 2077 if (private == NULL) { 2078 free(authctxt->oktypes); 2079 authctxt->oktypes = authctxt->ktypes = NULL; 2080 authctxt->active_ktype = NULL; 2081 debug("No more client hostkeys for hostbased authentication."); 2082 goto out; 2083 } 2084 2085 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2086 SSH_FP_DEFAULT)) == NULL) { 2087 error("%s: sshkey_fingerprint failed", __func__); 2088 goto out; 2089 } 2090 debug("%s: trying hostkey %s %s", 2091 __func__, sshkey_ssh_name(private), fp); 2092 2093 /* figure out a name for the client host */ 2094 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2095 if (lname == NULL) { 2096 error("%s: cannot get local ipaddr/name", __func__); 2097 goto out; 2098 } 2099 2100 /* XXX sshbuf_put_stringf? */ 2101 xasprintf(&chost, "%s.", lname); 2102 debug2("%s: chost %s", __func__, chost); 2103 2104 /* construct data */ 2105 if ((b = sshbuf_new()) == NULL) { 2106 error("%s: sshbuf_new failed", __func__); 2107 goto out; 2108 } 2109 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2110 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2111 goto out; 2112 } 2113 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2114 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2115 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2116 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2117 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2118 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2119 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2120 (r = sshbuf_put_cstring(b, chost)) != 0 || 2121 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2122 error("%s: buffer error: %s", __func__, ssh_err(r)); 2123 goto out; 2124 } 2125 2126 #ifdef DEBUG_PK 2127 sshbuf_dump(b, stderr); 2128 #endif 2129 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2130 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2131 error("sign using hostkey %s %s failed", 2132 sshkey_ssh_name(private), fp); 2133 goto out; 2134 } 2135 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2136 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2137 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2138 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2139 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2140 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2141 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2142 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2143 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2144 (r = sshpkt_send(ssh)) != 0) { 2145 error("%s: packet error: %s", __func__, ssh_err(r)); 2146 goto out; 2147 } 2148 success = 1; 2149 2150 out: 2151 if (sig != NULL) 2152 freezero(sig, siglen); 2153 free(keyblob); 2154 free(lname); 2155 free(fp); 2156 free(chost); 2157 sshkey_free(private); 2158 sshbuf_free(b); 2159 2160 return success; 2161 } 2162 2163 /* find auth method */ 2164 2165 /* 2166 * given auth method name, if configurable options permit this method fill 2167 * in auth_ident field and return true, otherwise return false. 2168 */ 2169 static int 2170 authmethod_is_enabled(Authmethod *method) 2171 { 2172 if (method == NULL) 2173 return 0; 2174 /* return false if options indicate this method is disabled */ 2175 if (method->enabled == NULL || *method->enabled == 0) 2176 return 0; 2177 /* return false if batch mode is enabled but method needs interactive mode */ 2178 if (method->batch_flag != NULL && *method->batch_flag != 0) 2179 return 0; 2180 return 1; 2181 } 2182 2183 static Authmethod * 2184 authmethod_lookup(const char *name) 2185 { 2186 Authmethod *method = NULL; 2187 if (name != NULL) 2188 for (method = authmethods; method->name != NULL; method++) 2189 if (strcmp(name, method->name) == 0) 2190 return method; 2191 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2192 return NULL; 2193 } 2194 2195 /* XXX internal state */ 2196 static Authmethod *current = NULL; 2197 static char *supported = NULL; 2198 static char *preferred = NULL; 2199 2200 /* 2201 * Given the authentication method list sent by the server, return the 2202 * next method we should try. If the server initially sends a nil list, 2203 * use a built-in default list. 2204 */ 2205 static Authmethod * 2206 authmethod_get(char *authlist) 2207 { 2208 char *name = NULL; 2209 u_int next; 2210 2211 /* Use a suitable default if we're passed a nil list. */ 2212 if (authlist == NULL || strlen(authlist) == 0) 2213 authlist = options.preferred_authentications; 2214 2215 if (supported == NULL || strcmp(authlist, supported) != 0) { 2216 debug3("start over, passed a different list %s", authlist); 2217 free(supported); 2218 supported = xstrdup(authlist); 2219 preferred = options.preferred_authentications; 2220 debug3("preferred %s", preferred); 2221 current = NULL; 2222 } else if (current != NULL && authmethod_is_enabled(current)) 2223 return current; 2224 2225 for (;;) { 2226 if ((name = match_list(preferred, supported, &next)) == NULL) { 2227 debug("No more authentication methods to try."); 2228 current = NULL; 2229 return NULL; 2230 } 2231 preferred += next; 2232 debug3("authmethod_lookup %s", name); 2233 debug3("remaining preferred: %s", preferred); 2234 if ((current = authmethod_lookup(name)) != NULL && 2235 authmethod_is_enabled(current)) { 2236 debug3("authmethod_is_enabled %s", name); 2237 debug("Next authentication method: %s", name); 2238 free(name); 2239 return current; 2240 } 2241 free(name); 2242 } 2243 } 2244 2245 static char * 2246 authmethods_get(void) 2247 { 2248 Authmethod *method = NULL; 2249 struct sshbuf *b; 2250 char *list; 2251 int r; 2252 2253 if ((b = sshbuf_new()) == NULL) 2254 fatal("%s: sshbuf_new failed", __func__); 2255 for (method = authmethods; method->name != NULL; method++) { 2256 if (authmethod_is_enabled(method)) { 2257 if ((r = sshbuf_putf(b, "%s%s", 2258 sshbuf_len(b) ? "," : "", method->name)) != 0) 2259 fatal("%s: buffer error: %s", 2260 __func__, ssh_err(r)); 2261 } 2262 } 2263 if ((list = sshbuf_dup_string(b)) == NULL) 2264 fatal("%s: sshbuf_dup_string failed", __func__); 2265 sshbuf_free(b); 2266 return list; 2267 } 2268