1 /* $OpenBSD: sshconnect2.c,v 1.284 2018/08/13 02:41:05 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/wait.h> 32 #include <sys/stat.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <netdb.h> 37 #include <pwd.h> 38 #include <signal.h> 39 #include <stdarg.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <unistd.h> 43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) 44 #include <vis.h> 45 #endif 46 47 #include "openbsd-compat/sys-queue.h" 48 49 #include "xmalloc.h" 50 #include "ssh.h" 51 #include "ssh2.h" 52 #include "sshbuf.h" 53 #include "packet.h" 54 #include "compat.h" 55 #include "cipher.h" 56 #include "sshkey.h" 57 #include "kex.h" 58 #include "myproposal.h" 59 #include "sshconnect.h" 60 #include "authfile.h" 61 #include "dh.h" 62 #include "authfd.h" 63 #include "log.h" 64 #include "misc.h" 65 #include "readconf.h" 66 #include "match.h" 67 #include "dispatch.h" 68 #include "canohost.h" 69 #include "msg.h" 70 #include "pathnames.h" 71 #include "uidswap.h" 72 #include "hostfile.h" 73 #include "ssherr.h" 74 #include "utf8.h" 75 76 #ifdef GSSAPI 77 #include "ssh-gss.h" 78 #endif 79 80 /* import */ 81 extern char *client_version_string; 82 extern char *server_version_string; 83 extern Options options; 84 85 /* 86 * SSH2 key exchange 87 */ 88 89 u_char *session_id2 = NULL; 90 u_int session_id2_len = 0; 91 92 char *xxx_host; 93 struct sockaddr *xxx_hostaddr; 94 95 static int 96 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 97 { 98 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 99 fatal("Host key verification failed."); 100 return 0; 101 } 102 103 static char * 104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 105 { 106 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 107 size_t maxlen; 108 struct hostkeys *hostkeys; 109 int ktype; 110 u_int i; 111 112 /* Find all hostkeys for this hostname */ 113 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 114 hostkeys = init_hostkeys(); 115 for (i = 0; i < options.num_user_hostfiles; i++) 116 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 117 for (i = 0; i < options.num_system_hostfiles; i++) 118 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 119 120 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 121 maxlen = strlen(avail) + 1; 122 first = xmalloc(maxlen); 123 last = xmalloc(maxlen); 124 *first = *last = '\0'; 125 126 #define ALG_APPEND(to, from) \ 127 do { \ 128 if (*to != '\0') \ 129 strlcat(to, ",", maxlen); \ 130 strlcat(to, from, maxlen); \ 131 } while (0) 132 133 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 134 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 135 fatal("%s: unknown alg %s", __func__, alg); 136 if (lookup_key_in_hostkeys_by_type(hostkeys, 137 sshkey_type_plain(ktype), NULL)) 138 ALG_APPEND(first, alg); 139 else 140 ALG_APPEND(last, alg); 141 } 142 #undef ALG_APPEND 143 xasprintf(&ret, "%s%s%s", first, 144 (*first == '\0' || *last == '\0') ? "" : ",", last); 145 if (*first != '\0') 146 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 147 148 free(first); 149 free(last); 150 free(hostname); 151 free(oavail); 152 free_hostkeys(hostkeys); 153 154 return ret; 155 } 156 157 void 158 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) 159 { 160 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 161 char *s, *all_key; 162 struct kex *kex; 163 int r; 164 165 xxx_host = host; 166 xxx_hostaddr = hostaddr; 167 168 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 169 fatal("%s: kex_names_cat", __func__); 170 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 171 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 172 compat_cipher_proposal(options.ciphers); 173 myproposal[PROPOSAL_ENC_ALGS_STOC] = 174 compat_cipher_proposal(options.ciphers); 175 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 176 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 177 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 178 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 179 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 180 if (options.hostkeyalgorithms != NULL) { 181 all_key = sshkey_alg_list(0, 0, 1, ','); 182 if (kex_assemble_names(&options.hostkeyalgorithms, 183 KEX_DEFAULT_PK_ALG, all_key) != 0) 184 fatal("%s: kex_assemble_namelist", __func__); 185 free(all_key); 186 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 187 compat_pkalg_proposal(options.hostkeyalgorithms); 188 } else { 189 /* Enforce default */ 190 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 191 /* Prefer algorithms that we already have keys for */ 192 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 193 compat_pkalg_proposal( 194 order_hostkeyalgs(host, hostaddr, port)); 195 } 196 197 if (options.rekey_limit || options.rekey_interval) 198 packet_set_rekey_limits(options.rekey_limit, 199 options.rekey_interval); 200 201 /* start key exchange */ 202 if ((r = kex_setup(active_state, myproposal)) != 0) 203 fatal("kex_setup: %s", ssh_err(r)); 204 kex = active_state->kex; 205 #ifdef WITH_OPENSSL 206 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 207 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 208 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; 209 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; 210 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; 211 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 212 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 213 # ifdef OPENSSL_HAS_ECC 214 kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 215 # endif 216 #endif 217 kex->kex[KEX_C25519_SHA256] = kexc25519_client; 218 kex->client_version_string=client_version_string; 219 kex->server_version_string=server_version_string; 220 kex->verify_host_key=&verify_host_key_callback; 221 222 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 223 224 /* remove ext-info from the KEX proposals for rekeying */ 225 myproposal[PROPOSAL_KEX_ALGS] = 226 compat_kex_proposal(options.kex_algorithms); 227 if ((r = kex_prop2buf(kex->my, myproposal)) != 0) 228 fatal("kex_prop2buf: %s", ssh_err(r)); 229 230 session_id2 = kex->session_id; 231 session_id2_len = kex->session_id_len; 232 233 #ifdef DEBUG_KEXDH 234 /* send 1st encrypted/maced/compressed message */ 235 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 236 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 237 (r = sshpkt_send(ssh)) != 0 || 238 (r = ssh_packet_write_wait(ssh)) != 0) 239 fatal("%s: %s", __func__, ssh_err(r)); 240 #endif 241 } 242 243 /* 244 * Authenticate user 245 */ 246 247 typedef struct cauthctxt Authctxt; 248 typedef struct cauthmethod Authmethod; 249 typedef struct identity Identity; 250 typedef struct idlist Idlist; 251 252 struct identity { 253 TAILQ_ENTRY(identity) next; 254 int agent_fd; /* >=0 if agent supports key */ 255 struct sshkey *key; /* public/private key */ 256 char *filename; /* comment for agent-only keys */ 257 int tried; 258 int isprivate; /* key points to the private key */ 259 int userprovided; 260 }; 261 TAILQ_HEAD(idlist, identity); 262 263 struct cauthctxt { 264 const char *server_user; 265 const char *local_user; 266 const char *host; 267 const char *service; 268 struct cauthmethod *method; 269 sig_atomic_t success; 270 char *authlist; 271 int attempt; 272 /* pubkey */ 273 struct idlist keys; 274 int agent_fd; 275 /* hostbased */ 276 Sensitive *sensitive; 277 char *oktypes, *ktypes; 278 const char *active_ktype; 279 /* kbd-interactive */ 280 int info_req_seen; 281 /* generic */ 282 void *methoddata; 283 }; 284 285 struct cauthmethod { 286 char *name; /* string to compare against server's list */ 287 int (*userauth)(Authctxt *authctxt); 288 void (*cleanup)(Authctxt *authctxt); 289 int *enabled; /* flag in option struct that enables method */ 290 int *batch_flag; /* flag in option struct that disables method */ 291 }; 292 293 int input_userauth_service_accept(int, u_int32_t, struct ssh *); 294 int input_userauth_ext_info(int, u_int32_t, struct ssh *); 295 int input_userauth_success(int, u_int32_t, struct ssh *); 296 int input_userauth_success_unexpected(int, u_int32_t, struct ssh *); 297 int input_userauth_failure(int, u_int32_t, struct ssh *); 298 int input_userauth_banner(int, u_int32_t, struct ssh *); 299 int input_userauth_error(int, u_int32_t, struct ssh *); 300 int input_userauth_info_req(int, u_int32_t, struct ssh *); 301 int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 302 int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 303 304 int userauth_none(Authctxt *); 305 int userauth_pubkey(Authctxt *); 306 int userauth_passwd(Authctxt *); 307 int userauth_kbdint(Authctxt *); 308 int userauth_hostbased(Authctxt *); 309 310 #ifdef GSSAPI 311 int userauth_gssapi(Authctxt *authctxt); 312 int input_gssapi_response(int type, u_int32_t, struct ssh *); 313 int input_gssapi_token(int type, u_int32_t, struct ssh *); 314 int input_gssapi_hash(int type, u_int32_t, struct ssh *); 315 int input_gssapi_error(int, u_int32_t, struct ssh *); 316 int input_gssapi_errtok(int, u_int32_t, struct ssh *); 317 #endif 318 319 void userauth(Authctxt *, char *); 320 321 static int sign_and_send_pubkey(struct ssh *ssh, Authctxt *, Identity *); 322 static void pubkey_prepare(Authctxt *); 323 static void pubkey_cleanup(Authctxt *); 324 static void pubkey_reset(Authctxt *); 325 static struct sshkey *load_identity_file(Identity *); 326 327 static Authmethod *authmethod_get(char *authlist); 328 static Authmethod *authmethod_lookup(const char *name); 329 static char *authmethods_get(void); 330 331 Authmethod authmethods[] = { 332 #ifdef GSSAPI 333 {"gssapi-with-mic", 334 userauth_gssapi, 335 NULL, 336 &options.gss_authentication, 337 NULL}, 338 #endif 339 {"hostbased", 340 userauth_hostbased, 341 NULL, 342 &options.hostbased_authentication, 343 NULL}, 344 {"publickey", 345 userauth_pubkey, 346 NULL, 347 &options.pubkey_authentication, 348 NULL}, 349 {"keyboard-interactive", 350 userauth_kbdint, 351 NULL, 352 &options.kbd_interactive_authentication, 353 &options.batch_mode}, 354 {"password", 355 userauth_passwd, 356 NULL, 357 &options.password_authentication, 358 &options.batch_mode}, 359 {"none", 360 userauth_none, 361 NULL, 362 NULL, 363 NULL}, 364 {NULL, NULL, NULL, NULL, NULL} 365 }; 366 367 void 368 ssh_userauth2(const char *local_user, const char *server_user, char *host, 369 Sensitive *sensitive) 370 { 371 struct ssh *ssh = active_state; 372 Authctxt authctxt; 373 int r; 374 375 if (options.challenge_response_authentication) 376 options.kbd_interactive_authentication = 1; 377 if (options.preferred_authentications == NULL) 378 options.preferred_authentications = authmethods_get(); 379 380 /* setup authentication context */ 381 memset(&authctxt, 0, sizeof(authctxt)); 382 pubkey_prepare(&authctxt); 383 authctxt.server_user = server_user; 384 authctxt.local_user = local_user; 385 authctxt.host = host; 386 authctxt.service = "ssh-connection"; /* service name */ 387 authctxt.success = 0; 388 authctxt.method = authmethod_lookup("none"); 389 authctxt.authlist = NULL; 390 authctxt.methoddata = NULL; 391 authctxt.sensitive = sensitive; 392 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 393 authctxt.info_req_seen = 0; 394 authctxt.agent_fd = -1; 395 if (authctxt.method == NULL) 396 fatal("ssh_userauth2: internal error: cannot send userauth none request"); 397 398 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 399 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 400 (r = sshpkt_send(ssh)) != 0) 401 fatal("%s: %s", __func__, ssh_err(r)); 402 403 ssh->authctxt = &authctxt; 404 ssh_dispatch_init(ssh, &input_userauth_error); 405 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 406 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 407 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 408 ssh->authctxt = NULL; 409 410 pubkey_cleanup(&authctxt); 411 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 412 413 if (!authctxt.success) 414 fatal("Authentication failed."); 415 debug("Authentication succeeded (%s).", authctxt.method->name); 416 } 417 418 /* ARGSUSED */ 419 int 420 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 421 { 422 Authctxt *authctxt = ssh->authctxt; 423 int r; 424 425 if (ssh_packet_remaining(ssh) > 0) { 426 char *reply; 427 428 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 429 goto out; 430 debug2("service_accept: %s", reply); 431 free(reply); 432 } else { 433 debug2("buggy server: service_accept w/o service"); 434 } 435 if ((r = sshpkt_get_end(ssh)) != 0) 436 goto out; 437 debug("SSH2_MSG_SERVICE_ACCEPT received"); 438 439 /* initial userauth request */ 440 userauth_none(authctxt); 441 442 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 443 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 444 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 445 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 446 r = 0; 447 out: 448 return r; 449 } 450 451 /* ARGSUSED */ 452 int 453 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 454 { 455 return kex_input_ext_info(type, seqnr, ssh); 456 } 457 458 void 459 userauth(Authctxt *authctxt, char *authlist) 460 { 461 struct ssh *ssh = active_state; /* XXX */ 462 463 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 464 authctxt->method->cleanup(authctxt); 465 466 free(authctxt->methoddata); 467 authctxt->methoddata = NULL; 468 if (authlist == NULL) { 469 authlist = authctxt->authlist; 470 } else { 471 free(authctxt->authlist); 472 authctxt->authlist = authlist; 473 } 474 for (;;) { 475 Authmethod *method = authmethod_get(authlist); 476 if (method == NULL) 477 fatal("%s@%s: Permission denied (%s).", 478 authctxt->server_user, authctxt->host, authlist); 479 authctxt->method = method; 480 481 /* reset the per method handler */ 482 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 483 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 484 485 /* and try new method */ 486 if (method->userauth(authctxt) != 0) { 487 debug2("we sent a %s packet, wait for reply", method->name); 488 break; 489 } else { 490 debug2("we did not send a packet, disable method"); 491 method->enabled = NULL; 492 } 493 } 494 } 495 496 /* ARGSUSED */ 497 int 498 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 499 { 500 fatal("input_userauth_error: bad message during authentication: " 501 "type %d", type); 502 return 0; 503 } 504 505 /* ARGSUSED */ 506 int 507 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 508 { 509 char *msg, *lang; 510 u_int len; 511 512 debug3("%s", __func__); 513 msg = packet_get_string(&len); 514 lang = packet_get_string(NULL); 515 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 516 fmprintf(stderr, "%s", msg); 517 free(msg); 518 free(lang); 519 return 0; 520 } 521 522 /* ARGSUSED */ 523 int 524 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 525 { 526 Authctxt *authctxt = ssh->authctxt; 527 528 if (authctxt == NULL) 529 fatal("input_userauth_success: no authentication context"); 530 free(authctxt->authlist); 531 authctxt->authlist = NULL; 532 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 533 authctxt->method->cleanup(authctxt); 534 free(authctxt->methoddata); 535 authctxt->methoddata = NULL; 536 authctxt->success = 1; /* break out */ 537 return 0; 538 } 539 540 int 541 input_userauth_success_unexpected(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__); 547 548 fatal("Unexpected authentication success during %s.", 549 authctxt->method->name); 550 return 0; 551 } 552 553 /* ARGSUSED */ 554 int 555 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 556 { 557 Authctxt *authctxt = ssh->authctxt; 558 char *authlist = NULL; 559 u_char partial; 560 int r; 561 562 if (authctxt == NULL) 563 fatal("input_userauth_failure: no authentication context"); 564 565 if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 || 566 (r = sshpkt_get_u8(ssh, &partial)) != 0 || 567 (r = sshpkt_get_end(ssh)) != 0) 568 goto out; 569 570 if (partial != 0) { 571 verbose("Authenticated with partial success."); 572 /* reset state */ 573 pubkey_reset(authctxt); 574 } 575 debug("Authentications that can continue: %s", authlist); 576 577 userauth(authctxt, authlist); 578 authlist = NULL; 579 out: 580 free(authlist); 581 return 0; 582 } 583 584 /* ARGSUSED */ 585 int 586 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 587 { 588 Authctxt *authctxt = ssh->authctxt; 589 struct sshkey *key = NULL; 590 Identity *id = NULL; 591 int pktype, sent = 0; 592 size_t blen; 593 char *pkalg = NULL, *fp; 594 u_char *pkblob = NULL; 595 int r; 596 597 if (authctxt == NULL) 598 fatal("input_userauth_pk_ok: no authentication context"); 599 600 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 601 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 602 (r = sshpkt_get_end(ssh)) != 0) 603 goto done; 604 605 debug("Server accepts key: pkalg %s blen %zu", pkalg, blen); 606 607 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 608 debug("unknown pkalg %s", pkalg); 609 goto done; 610 } 611 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 612 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 613 goto done; 614 } 615 if (key->type != pktype) { 616 error("input_userauth_pk_ok: type mismatch " 617 "for decoded key (received %d, expected %d)", 618 key->type, pktype); 619 goto done; 620 } 621 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 622 SSH_FP_DEFAULT)) == NULL) 623 goto done; 624 debug2("input_userauth_pk_ok: fp %s", fp); 625 free(fp); 626 627 /* 628 * search keys in the reverse order, because last candidate has been 629 * moved to the end of the queue. this also avoids confusion by 630 * duplicate keys 631 */ 632 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 633 if (sshkey_equal(key, id->key)) { 634 sent = sign_and_send_pubkey(ssh, authctxt, id); 635 break; 636 } 637 } 638 r = 0; 639 done: 640 sshkey_free(key); 641 free(pkalg); 642 free(pkblob); 643 644 /* try another method if we did not send a packet */ 645 if (r == 0 && sent == 0) 646 userauth(authctxt, NULL); 647 return r; 648 } 649 650 #ifdef GSSAPI 651 int 652 userauth_gssapi(Authctxt *authctxt) 653 { 654 struct ssh *ssh = active_state; /* XXX */ 655 Gssctxt *gssctxt = NULL; 656 static gss_OID_set gss_supported = NULL; 657 static u_int mech = 0; 658 OM_uint32 min; 659 int r, ok = 0; 660 661 /* Try one GSSAPI method at a time, rather than sending them all at 662 * once. */ 663 664 if (gss_supported == NULL) 665 gss_indicate_mechs(&min, &gss_supported); 666 667 /* Check to see if the mechanism is usable before we offer it */ 668 while (mech < gss_supported->count && !ok) { 669 /* My DER encoding requires length<128 */ 670 if (gss_supported->elements[mech].length < 128 && 671 ssh_gssapi_check_mechanism(&gssctxt, 672 &gss_supported->elements[mech], authctxt->host)) { 673 ok = 1; /* Mechanism works */ 674 } else { 675 mech++; 676 } 677 } 678 679 if (!ok) 680 return 0; 681 682 authctxt->methoddata=(void *)gssctxt; 683 684 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 685 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 686 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 687 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 688 (r = sshpkt_put_u32(ssh, 1)) != 0 || 689 (r = sshpkt_put_u32(ssh, 690 (gss_supported->elements[mech].length) + 2)) != 0 || 691 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 692 (r = sshpkt_put_u8(ssh, 693 gss_supported->elements[mech].length)) != 0 || 694 (r = sshpkt_put(ssh, 695 gss_supported->elements[mech].elements, 696 gss_supported->elements[mech].length)) != 0 || 697 (r = sshpkt_send(ssh)) != 0) 698 fatal("%s: %s", __func__, ssh_err(r)); 699 700 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 701 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 702 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 703 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 704 705 mech++; /* Move along to next candidate */ 706 707 return 1; 708 } 709 710 static OM_uint32 711 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 712 { 713 Authctxt *authctxt = ssh->authctxt; 714 Gssctxt *gssctxt = authctxt->methoddata; 715 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 716 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 717 gss_buffer_desc gssbuf; 718 OM_uint32 status, ms, flags; 719 int r; 720 721 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 722 recv_tok, &send_tok, &flags); 723 724 if (send_tok.length > 0) { 725 u_char type = GSS_ERROR(status) ? 726 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 727 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 728 729 if ((r = sshpkt_start(ssh, type)) != 0 || 730 (r = sshpkt_put_string(ssh, send_tok.value, 731 send_tok.length)) != 0 || 732 (r = sshpkt_send(ssh)) != 0) 733 fatal("%s: %s", __func__, ssh_err(r)); 734 735 gss_release_buffer(&ms, &send_tok); 736 } 737 738 if (status == GSS_S_COMPLETE) { 739 /* send either complete or MIC, depending on mechanism */ 740 if (!(flags & GSS_C_INTEG_FLAG)) { 741 if ((r = sshpkt_start(ssh, 742 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 743 (r = sshpkt_send(ssh)) != 0) 744 fatal("%s: %s", __func__, ssh_err(r)); 745 } else { 746 struct sshbuf *b; 747 748 if ((b = sshbuf_new()) == NULL) 749 fatal("%s: sshbuf_new failed", __func__); 750 ssh_gssapi_buildmic(b, authctxt->server_user, 751 authctxt->service, "gssapi-with-mic"); 752 753 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 754 fatal("%s: sshbuf_mutable_ptr failed", __func__); 755 gssbuf.length = sshbuf_len(b); 756 757 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 758 759 if (!GSS_ERROR(status)) { 760 if ((r = sshpkt_start(ssh, 761 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 762 (r = sshpkt_put_string(ssh, mic.value, 763 mic.length)) != 0 || 764 (r = sshpkt_send(ssh)) != 0) 765 fatal("%s: %s", __func__, ssh_err(r)); 766 } 767 768 sshbuf_free(b); 769 gss_release_buffer(&ms, &mic); 770 } 771 } 772 773 return status; 774 } 775 776 /* ARGSUSED */ 777 int 778 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 779 { 780 Authctxt *authctxt = ssh->authctxt; 781 Gssctxt *gssctxt; 782 size_t oidlen; 783 u_char *oidv = NULL; 784 int r; 785 786 if (authctxt == NULL) 787 fatal("input_gssapi_response: no authentication context"); 788 gssctxt = authctxt->methoddata; 789 790 /* Setup our OID */ 791 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 792 goto done; 793 794 if (oidlen <= 2 || 795 oidv[0] != SSH_GSS_OIDTYPE || 796 oidv[1] != oidlen - 2) { 797 debug("Badly encoded mechanism OID received"); 798 userauth(authctxt, NULL); 799 goto ok; 800 } 801 802 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 803 fatal("Server returned different OID than expected"); 804 805 if ((r = sshpkt_get_end(ssh)) != 0) 806 goto done; 807 808 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 809 /* Start again with next method on list */ 810 debug("Trying to start again"); 811 userauth(authctxt, NULL); 812 goto ok; 813 } 814 ok: 815 r = 0; 816 done: 817 free(oidv); 818 return r; 819 } 820 821 /* ARGSUSED */ 822 int 823 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 824 { 825 Authctxt *authctxt = ssh->authctxt; 826 gss_buffer_desc recv_tok; 827 u_char *p = NULL; 828 size_t len; 829 OM_uint32 status; 830 int r; 831 832 if (authctxt == NULL) 833 fatal("input_gssapi_response: no authentication context"); 834 835 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 836 (r = sshpkt_get_end(ssh)) != 0) 837 goto out; 838 839 recv_tok.value = p; 840 recv_tok.length = len; 841 status = process_gssapi_token(ssh, &recv_tok); 842 843 /* Start again with the next method in the list */ 844 if (GSS_ERROR(status)) { 845 userauth(authctxt, NULL); 846 /* ok */ 847 } 848 r = 0; 849 out: 850 free(p); 851 return r; 852 } 853 854 /* ARGSUSED */ 855 int 856 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 857 { 858 Authctxt *authctxt = ssh->authctxt; 859 Gssctxt *gssctxt; 860 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 861 gss_buffer_desc recv_tok; 862 OM_uint32 ms; 863 u_char *p = NULL; 864 size_t len; 865 int r; 866 867 if (authctxt == NULL) 868 fatal("input_gssapi_response: no authentication context"); 869 gssctxt = authctxt->methoddata; 870 871 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 872 (r = sshpkt_get_end(ssh)) != 0) { 873 free(p); 874 return r; 875 } 876 877 /* Stick it into GSSAPI and see what it says */ 878 recv_tok.value = p; 879 recv_tok.length = len; 880 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 881 &recv_tok, &send_tok, NULL); 882 free(p); 883 gss_release_buffer(&ms, &send_tok); 884 885 /* Server will be returning a failed packet after this one */ 886 return 0; 887 } 888 889 /* ARGSUSED */ 890 int 891 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 892 { 893 char *msg = NULL; 894 char *lang = NULL; 895 int r; 896 897 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 898 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 899 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 900 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 901 goto out; 902 r = sshpkt_get_end(ssh); 903 debug("Server GSSAPI Error:\n%s", msg); 904 out: 905 free(msg); 906 free(lang); 907 return r; 908 } 909 #endif /* GSSAPI */ 910 911 int 912 userauth_none(Authctxt *authctxt) 913 { 914 struct ssh *ssh = active_state; /* XXX */ 915 int r; 916 917 /* initial userauth request */ 918 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 919 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 920 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 921 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 922 (r = sshpkt_send(ssh)) != 0) 923 fatal("%s: %s", __func__, ssh_err(r)); 924 return 1; 925 } 926 927 int 928 userauth_passwd(Authctxt *authctxt) 929 { 930 struct ssh *ssh = active_state; /* XXX */ 931 static int attempt = 0; 932 char prompt[256]; 933 char *password; 934 const char *host = options.host_key_alias ? options.host_key_alias : 935 authctxt->host; 936 int r; 937 938 if (attempt++ >= options.number_of_password_prompts) 939 return 0; 940 941 if (attempt != 1) 942 error("Permission denied, please try again."); 943 944 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", 945 authctxt->server_user, host); 946 password = read_passphrase(prompt, 0); 947 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 948 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 949 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 950 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 951 (r = sshpkt_put_u8(ssh, 0)) != 0 || 952 (r = sshpkt_put_cstring(ssh, password)) != 0 || 953 (r = sshpkt_add_padding(ssh, 64)) != 0 || 954 (r = sshpkt_send(ssh)) != 0) 955 fatal("%s: %s", __func__, ssh_err(r)); 956 957 if (password) 958 freezero(password, strlen(password)); 959 960 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 961 &input_userauth_passwd_changereq); 962 963 return 1; 964 } 965 966 /* 967 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 968 */ 969 /* ARGSUSED */ 970 int 971 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 972 { 973 Authctxt *authctxt = ssh->authctxt; 974 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 975 char prompt[256]; 976 const char *host; 977 int r; 978 979 debug2("input_userauth_passwd_changereq"); 980 981 if (authctxt == NULL) 982 fatal("input_userauth_passwd_changereq: " 983 "no authentication context"); 984 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 985 986 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 987 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 988 goto out; 989 if (strlen(info) > 0) 990 logit("%s", info); 991 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 992 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 993 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 994 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 995 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 996 goto out; 997 998 snprintf(prompt, sizeof(prompt), 999 "Enter %.30s@%.128s's old password: ", 1000 authctxt->server_user, host); 1001 password = read_passphrase(prompt, 0); 1002 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1003 goto out; 1004 1005 freezero(password, strlen(password)); 1006 password = NULL; 1007 while (password == NULL) { 1008 snprintf(prompt, sizeof(prompt), 1009 "Enter %.30s@%.128s's new password: ", 1010 authctxt->server_user, host); 1011 password = read_passphrase(prompt, RP_ALLOW_EOF); 1012 if (password == NULL) { 1013 /* bail out */ 1014 r = 0; 1015 goto out; 1016 } 1017 snprintf(prompt, sizeof(prompt), 1018 "Retype %.30s@%.128s's new password: ", 1019 authctxt->server_user, host); 1020 retype = read_passphrase(prompt, 0); 1021 if (strcmp(password, retype) != 0) { 1022 freezero(password, strlen(password)); 1023 logit("Mismatch; try again, EOF to quit."); 1024 password = NULL; 1025 } 1026 freezero(retype, strlen(retype)); 1027 } 1028 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1029 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1030 (r = sshpkt_send(ssh)) != 0) 1031 goto out; 1032 1033 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1034 &input_userauth_passwd_changereq); 1035 r = 0; 1036 out: 1037 if (password) 1038 freezero(password, strlen(password)); 1039 free(info); 1040 free(lang); 1041 return r; 1042 } 1043 1044 /* 1045 * Select an algorithm for publickey signatures. 1046 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1047 * 1048 * Call with ssh==NULL to ignore server-sig-algs extension list and 1049 * only attempt with the key's base signature type. 1050 */ 1051 static char * 1052 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1053 { 1054 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1055 1056 /* 1057 * The signature algorithm will only differ from the key algorithm 1058 * for RSA keys/certs and when the server advertises support for 1059 * newer (SHA2) algorithms. 1060 */ 1061 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1062 (key->type != KEY_RSA && key->type != KEY_RSA_CERT)) { 1063 /* Filter base key signature alg against our configuration */ 1064 return match_list(sshkey_ssh_name(key), 1065 options.pubkey_key_types, NULL); 1066 } 1067 1068 /* 1069 * For RSA keys/certs, since these might have a different sig type: 1070 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1071 * that also appears in the supported signature algorithms list from 1072 * the server. 1073 */ 1074 oallowed = allowed = xstrdup(options.pubkey_key_types); 1075 while ((cp = strsep(&allowed, ",")) != NULL) { 1076 if (sshkey_type_from_name(cp) != key->type) 1077 continue; 1078 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1079 if (tmp != NULL) 1080 alg = xstrdup(cp); 1081 free(tmp); 1082 if (alg != NULL) 1083 break; 1084 } 1085 free(oallowed); 1086 return alg; 1087 } 1088 1089 static int 1090 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1091 const u_char *data, size_t datalen, u_int compat, const char *alg) 1092 { 1093 struct sshkey *prv; 1094 int r; 1095 1096 /* The agent supports this key. */ 1097 if (id->key != NULL && id->agent_fd != -1) { 1098 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1099 data, datalen, alg, compat); 1100 } 1101 1102 /* 1103 * We have already loaded the private key or the private key is 1104 * stored in external hardware. 1105 */ 1106 if (id->key != NULL && 1107 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1108 if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen, 1109 alg, compat)) != 0) 1110 return r; 1111 /* 1112 * PKCS#11 tokens may not support all signature algorithms, 1113 * so check what we get back. 1114 */ 1115 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) 1116 return r; 1117 return 0; 1118 } 1119 1120 /* Load the private key from the file. */ 1121 if ((prv = load_identity_file(id)) == NULL) 1122 return SSH_ERR_KEY_NOT_FOUND; 1123 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1124 error("%s: private key %s contents do not match public", 1125 __func__, id->filename); 1126 return SSH_ERR_KEY_NOT_FOUND; 1127 } 1128 r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1129 sshkey_free(prv); 1130 return r; 1131 } 1132 1133 static int 1134 id_filename_matches(Identity *id, Identity *private_id) 1135 { 1136 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1137 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1138 size_t i, slen; 1139 1140 if (strcmp(id->filename, private_id->filename) == 0) 1141 return 1; 1142 for (i = 0; suffixes[i]; i++) { 1143 slen = strlen(suffixes[i]); 1144 if (len > slen && plen == len - slen && 1145 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1146 memcmp(id->filename, private_id->filename, plen) == 0) 1147 return 1; 1148 } 1149 return 0; 1150 } 1151 1152 static int 1153 sign_and_send_pubkey(struct ssh *ssh, Authctxt *authctxt, Identity *id) 1154 { 1155 struct sshbuf *b = NULL; 1156 Identity *private_id, *sign_id = NULL; 1157 u_char *signature = NULL; 1158 size_t slen = 0, skip = 0; 1159 int r, fallback_sigtype, sent = 0; 1160 char *alg = NULL, *fp = NULL; 1161 const char *loc = ""; 1162 1163 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1164 SSH_FP_DEFAULT)) == NULL) 1165 return 0; 1166 1167 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1168 1169 /* 1170 * If the key is an certificate, try to find a matching private key 1171 * and use it to complete the signature. 1172 * If no such private key exists, fall back to trying the certificate 1173 * key itself in case it has a private half already loaded. 1174 * This will try to set sign_id to the private key that will perform 1175 * the signature. 1176 */ 1177 if (sshkey_is_cert(id->key)) { 1178 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1179 if (sshkey_equal_public(id->key, private_id->key) && 1180 id->key->type != private_id->key->type) { 1181 sign_id = private_id; 1182 break; 1183 } 1184 } 1185 /* 1186 * Exact key matches are preferred, but also allow 1187 * filename matches for non-PKCS#11/agent keys that 1188 * didn't load public keys. This supports the case 1189 * of keeping just a private key file and public 1190 * certificate on disk. 1191 */ 1192 if (sign_id == NULL && 1193 !id->isprivate && id->agent_fd == -1 && 1194 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1195 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1196 if (private_id->key == NULL && 1197 id_filename_matches(id, private_id)) { 1198 sign_id = private_id; 1199 break; 1200 } 1201 } 1202 } 1203 if (sign_id != NULL) { 1204 debug2("%s: using private key \"%s\"%s for " 1205 "certificate", __func__, id->filename, 1206 id->agent_fd != -1 ? " from agent" : ""); 1207 } else { 1208 debug("%s: no separate private key for certificate " 1209 "\"%s\"", __func__, id->filename); 1210 } 1211 } 1212 1213 /* 1214 * If the above didn't select another identity to do the signing 1215 * then default to the one we started with. 1216 */ 1217 if (sign_id == NULL) 1218 sign_id = id; 1219 1220 /* assemble and sign data */ 1221 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1222 free(alg); 1223 slen = 0; 1224 signature = NULL; 1225 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1226 id->key)) == NULL) { 1227 error("%s: no mutual signature supported", __func__); 1228 goto out; 1229 } 1230 debug3("%s: signing using %s", __func__, alg); 1231 1232 sshbuf_free(b); 1233 if ((b = sshbuf_new()) == NULL) 1234 fatal("%s: sshbuf_new failed", __func__); 1235 if (datafellows & SSH_OLD_SESSIONID) { 1236 if ((r = sshbuf_put(b, session_id2, 1237 session_id2_len)) != 0) { 1238 fatal("%s: sshbuf_put: %s", 1239 __func__, ssh_err(r)); 1240 } 1241 } else { 1242 if ((r = sshbuf_put_string(b, session_id2, 1243 session_id2_len)) != 0) { 1244 fatal("%s: sshbuf_put_string: %s", 1245 __func__, ssh_err(r)); 1246 } 1247 } 1248 skip = sshbuf_len(b); 1249 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1250 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1251 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1252 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1253 (r = sshbuf_put_u8(b, 1)) != 0 || 1254 (r = sshbuf_put_cstring(b, alg)) != 0 || 1255 (r = sshkey_puts(id->key, b)) != 0) { 1256 fatal("%s: assemble signed data: %s", 1257 __func__, ssh_err(r)); 1258 } 1259 1260 /* generate signature */ 1261 r = identity_sign(sign_id, &signature, &slen, 1262 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1263 if (r == 0) 1264 break; 1265 else if (r == SSH_ERR_KEY_NOT_FOUND) 1266 goto out; /* soft failure */ 1267 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1268 !fallback_sigtype) { 1269 if (sign_id->agent_fd != -1) 1270 loc = "agent "; 1271 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1272 loc = "token "; 1273 logit("%skey %s %s returned incorrect signature type", 1274 loc, sshkey_type(id->key), fp); 1275 continue; 1276 } 1277 error("%s: signing failed: %s", __func__, ssh_err(r)); 1278 goto out; 1279 } 1280 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1281 fatal("%s: no signature", __func__); 1282 1283 /* append signature */ 1284 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1285 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1286 1287 #ifdef DEBUG_PK 1288 sshbuf_dump(b, stderr); 1289 #endif 1290 /* skip session id and packet type */ 1291 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1292 fatal("%s: consume: %s", __func__, ssh_err(r)); 1293 1294 /* put remaining data from buffer into packet */ 1295 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1296 (r = sshpkt_putb(ssh, b)) != 0 || 1297 (r = sshpkt_send(ssh)) != 0) 1298 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1299 1300 /* success */ 1301 sent = 1; 1302 1303 out: 1304 free(fp); 1305 free(alg); 1306 sshbuf_free(b); 1307 freezero(signature, slen); 1308 return sent; 1309 } 1310 1311 static int 1312 send_pubkey_test(struct ssh *ssh, Authctxt *authctxt, Identity *id) 1313 { 1314 u_char *blob = NULL; 1315 char *alg = NULL; 1316 size_t bloblen; 1317 u_int have_sig = 0; 1318 int sent = 0, r; 1319 1320 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1321 debug("%s: no mutual signature algorithm", __func__); 1322 goto out; 1323 } 1324 1325 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1326 /* we cannot handle this key */ 1327 debug3("%s: cannot handle key", __func__); 1328 goto out; 1329 } 1330 /* register callback for USERAUTH_PK_OK message */ 1331 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1332 1333 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1334 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1335 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1336 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1337 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1338 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1339 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1340 (r = sshpkt_send(ssh)) != 0) 1341 fatal("%s: %s", __func__, ssh_err(r)); 1342 sent = 1; 1343 1344 out: 1345 free(alg); 1346 free(blob); 1347 return sent; 1348 } 1349 1350 static struct sshkey * 1351 load_identity_file(Identity *id) 1352 { 1353 struct sshkey *private = NULL; 1354 char prompt[300], *passphrase, *comment; 1355 int r, perm_ok = 0, quit = 0, i; 1356 struct stat st; 1357 1358 if (stat(id->filename, &st) < 0) { 1359 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1360 id->filename, strerror(errno)); 1361 return NULL; 1362 } 1363 snprintf(prompt, sizeof prompt, 1364 "Enter passphrase for key '%.100s': ", id->filename); 1365 for (i = 0; i <= options.number_of_password_prompts; i++) { 1366 if (i == 0) 1367 passphrase = ""; 1368 else { 1369 passphrase = read_passphrase(prompt, 0); 1370 if (*passphrase == '\0') { 1371 debug2("no passphrase given, try next key"); 1372 free(passphrase); 1373 break; 1374 } 1375 } 1376 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1377 passphrase, &private, &comment, &perm_ok))) { 1378 case 0: 1379 break; 1380 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1381 if (options.batch_mode) { 1382 quit = 1; 1383 break; 1384 } 1385 if (i != 0) 1386 debug2("bad passphrase given, try again..."); 1387 break; 1388 case SSH_ERR_SYSTEM_ERROR: 1389 if (errno == ENOENT) { 1390 debug2("Load key \"%s\": %s", 1391 id->filename, ssh_err(r)); 1392 quit = 1; 1393 break; 1394 } 1395 /* FALLTHROUGH */ 1396 default: 1397 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1398 quit = 1; 1399 break; 1400 } 1401 if (!quit && private != NULL && id->agent_fd == -1 && 1402 !(id->key && id->isprivate)) 1403 maybe_add_key_to_agent(id->filename, private, comment, 1404 passphrase); 1405 if (i > 0) 1406 freezero(passphrase, strlen(passphrase)); 1407 free(comment); 1408 if (private != NULL || quit) 1409 break; 1410 } 1411 return private; 1412 } 1413 1414 static int 1415 key_type_allowed_by_config(struct sshkey *key) 1416 { 1417 if (match_pattern_list(sshkey_ssh_name(key), 1418 options.pubkey_key_types, 0) == 1) 1419 return 1; 1420 1421 /* RSA keys/certs might be allowed by alternate signature types */ 1422 switch (key->type) { 1423 case KEY_RSA: 1424 if (match_pattern_list("rsa-sha2-512", 1425 options.pubkey_key_types, 0) == 1) 1426 return 1; 1427 if (match_pattern_list("rsa-sha2-256", 1428 options.pubkey_key_types, 0) == 1) 1429 return 1; 1430 break; 1431 case KEY_RSA_CERT: 1432 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1433 options.pubkey_key_types, 0) == 1) 1434 return 1; 1435 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1436 options.pubkey_key_types, 0) == 1) 1437 return 1; 1438 break; 1439 } 1440 return 0; 1441 } 1442 1443 1444 /* 1445 * try keys in the following order: 1446 * 1. certificates listed in the config file 1447 * 2. other input certificates 1448 * 3. agent keys that are found in the config file 1449 * 4. other agent keys 1450 * 5. keys that are only listed in the config file 1451 */ 1452 static void 1453 pubkey_prepare(Authctxt *authctxt) 1454 { 1455 struct identity *id, *id2, *tmp; 1456 struct idlist agent, files, *preferred; 1457 struct sshkey *key; 1458 int agent_fd = -1, i, r, found; 1459 size_t j; 1460 struct ssh_identitylist *idlist; 1461 1462 TAILQ_INIT(&agent); /* keys from the agent */ 1463 TAILQ_INIT(&files); /* keys from the config file */ 1464 preferred = &authctxt->keys; 1465 TAILQ_INIT(preferred); /* preferred order of keys */ 1466 1467 /* list of keys stored in the filesystem and PKCS#11 */ 1468 for (i = 0; i < options.num_identity_files; i++) { 1469 key = options.identity_keys[i]; 1470 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1471 continue; 1472 options.identity_keys[i] = NULL; 1473 id = xcalloc(1, sizeof(*id)); 1474 id->agent_fd = -1; 1475 id->key = key; 1476 id->filename = xstrdup(options.identity_files[i]); 1477 id->userprovided = options.identity_file_userprovided[i]; 1478 TAILQ_INSERT_TAIL(&files, id, next); 1479 } 1480 /* list of certificates specified by user */ 1481 for (i = 0; i < options.num_certificate_files; i++) { 1482 key = options.certificates[i]; 1483 if (!sshkey_is_cert(key) || key->cert == NULL || 1484 key->cert->type != SSH2_CERT_TYPE_USER) 1485 continue; 1486 id = xcalloc(1, sizeof(*id)); 1487 id->agent_fd = -1; 1488 id->key = key; 1489 id->filename = xstrdup(options.certificate_files[i]); 1490 id->userprovided = options.certificate_file_userprovided[i]; 1491 TAILQ_INSERT_TAIL(preferred, id, next); 1492 } 1493 /* list of keys supported by the agent */ 1494 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1495 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1496 debug("%s: ssh_get_authentication_socket: %s", 1497 __func__, ssh_err(r)); 1498 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1499 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1500 debug("%s: ssh_fetch_identitylist: %s", 1501 __func__, ssh_err(r)); 1502 close(agent_fd); 1503 } else { 1504 for (j = 0; j < idlist->nkeys; j++) { 1505 found = 0; 1506 TAILQ_FOREACH(id, &files, next) { 1507 /* 1508 * agent keys from the config file are 1509 * preferred 1510 */ 1511 if (sshkey_equal(idlist->keys[j], id->key)) { 1512 TAILQ_REMOVE(&files, id, next); 1513 TAILQ_INSERT_TAIL(preferred, id, next); 1514 id->agent_fd = agent_fd; 1515 found = 1; 1516 break; 1517 } 1518 } 1519 if (!found && !options.identities_only) { 1520 id = xcalloc(1, sizeof(*id)); 1521 /* XXX "steals" key/comment from idlist */ 1522 id->key = idlist->keys[j]; 1523 id->filename = idlist->comments[j]; 1524 idlist->keys[j] = NULL; 1525 idlist->comments[j] = NULL; 1526 id->agent_fd = agent_fd; 1527 TAILQ_INSERT_TAIL(&agent, id, next); 1528 } 1529 } 1530 ssh_free_identitylist(idlist); 1531 /* append remaining agent keys */ 1532 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1533 TAILQ_REMOVE(&agent, id, next); 1534 TAILQ_INSERT_TAIL(preferred, id, next); 1535 } 1536 authctxt->agent_fd = agent_fd; 1537 } 1538 /* Prefer PKCS11 keys that are explicitly listed */ 1539 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1540 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1541 continue; 1542 found = 0; 1543 TAILQ_FOREACH(id2, &files, next) { 1544 if (id2->key == NULL || 1545 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1546 continue; 1547 if (sshkey_equal(id->key, id2->key)) { 1548 TAILQ_REMOVE(&files, id, next); 1549 TAILQ_INSERT_TAIL(preferred, id, next); 1550 found = 1; 1551 break; 1552 } 1553 } 1554 /* If IdentitiesOnly set and key not found then don't use it */ 1555 if (!found && options.identities_only) { 1556 TAILQ_REMOVE(&files, id, next); 1557 freezero(id, sizeof(*id)); 1558 } 1559 } 1560 /* append remaining keys from the config file */ 1561 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1562 TAILQ_REMOVE(&files, id, next); 1563 TAILQ_INSERT_TAIL(preferred, id, next); 1564 } 1565 /* finally, filter by PubkeyAcceptedKeyTypes */ 1566 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1567 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1568 debug("Skipping %s key %s - " 1569 "not in PubkeyAcceptedKeyTypes", 1570 sshkey_ssh_name(id->key), id->filename); 1571 TAILQ_REMOVE(preferred, id, next); 1572 sshkey_free(id->key); 1573 free(id->filename); 1574 memset(id, 0, sizeof(*id)); 1575 continue; 1576 } 1577 debug2("key: %s (%p)%s%s", id->filename, id->key, 1578 id->userprovided ? ", explicit" : "", 1579 id->agent_fd != -1 ? ", agent" : ""); 1580 } 1581 } 1582 1583 static void 1584 pubkey_cleanup(Authctxt *authctxt) 1585 { 1586 Identity *id; 1587 1588 if (authctxt->agent_fd != -1) 1589 ssh_close_authentication_socket(authctxt->agent_fd); 1590 for (id = TAILQ_FIRST(&authctxt->keys); id; 1591 id = TAILQ_FIRST(&authctxt->keys)) { 1592 TAILQ_REMOVE(&authctxt->keys, id, next); 1593 sshkey_free(id->key); 1594 free(id->filename); 1595 free(id); 1596 } 1597 } 1598 1599 static void 1600 pubkey_reset(Authctxt *authctxt) 1601 { 1602 Identity *id; 1603 1604 TAILQ_FOREACH(id, &authctxt->keys, next) 1605 id->tried = 0; 1606 } 1607 1608 static int 1609 try_identity(Identity *id) 1610 { 1611 if (!id->key) 1612 return (0); 1613 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1614 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1615 debug("Skipped %s key %s for RSA/MD5 server", 1616 sshkey_type(id->key), id->filename); 1617 return (0); 1618 } 1619 return 1; 1620 } 1621 1622 int 1623 userauth_pubkey(Authctxt *authctxt) 1624 { 1625 struct ssh *ssh = active_state; /* XXX */ 1626 Identity *id; 1627 int sent = 0; 1628 char *fp; 1629 1630 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1631 if (id->tried++) 1632 return (0); 1633 /* move key to the end of the queue */ 1634 TAILQ_REMOVE(&authctxt->keys, id, next); 1635 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1636 /* 1637 * send a test message if we have the public key. for 1638 * encrypted keys we cannot do this and have to load the 1639 * private key instead 1640 */ 1641 if (id->key != NULL) { 1642 if (try_identity(id)) { 1643 if ((fp = sshkey_fingerprint(id->key, 1644 options.fingerprint_hash, 1645 SSH_FP_DEFAULT)) == NULL) { 1646 error("%s: sshkey_fingerprint failed", 1647 __func__); 1648 return 0; 1649 } 1650 debug("Offering public key: %s %s %s", 1651 sshkey_type(id->key), fp, id->filename); 1652 free(fp); 1653 sent = send_pubkey_test(ssh, authctxt, id); 1654 } 1655 } else { 1656 debug("Trying private key: %s", id->filename); 1657 id->key = load_identity_file(id); 1658 if (id->key != NULL) { 1659 if (try_identity(id)) { 1660 id->isprivate = 1; 1661 sent = sign_and_send_pubkey(ssh, 1662 authctxt, id); 1663 } 1664 sshkey_free(id->key); 1665 id->key = NULL; 1666 id->isprivate = 0; 1667 } 1668 } 1669 if (sent) 1670 return (sent); 1671 } 1672 return (0); 1673 } 1674 1675 /* 1676 * Send userauth request message specifying keyboard-interactive method. 1677 */ 1678 int 1679 userauth_kbdint(Authctxt *authctxt) 1680 { 1681 struct ssh *ssh = active_state; /* XXX */ 1682 static int attempt = 0; 1683 int r; 1684 1685 if (attempt++ >= options.number_of_password_prompts) 1686 return 0; 1687 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1688 if (attempt > 1 && !authctxt->info_req_seen) { 1689 debug3("userauth_kbdint: disable: no info_req_seen"); 1690 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1691 return 0; 1692 } 1693 1694 debug2("userauth_kbdint"); 1695 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1696 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1697 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1698 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1699 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1700 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1701 options.kbd_interactive_devices : "")) != 0 || 1702 (r = sshpkt_send(ssh)) != 0) 1703 fatal("%s: %s", __func__, ssh_err(r)); 1704 1705 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1706 return 1; 1707 } 1708 1709 /* 1710 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1711 */ 1712 int 1713 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1714 { 1715 Authctxt *authctxt = ssh->authctxt; 1716 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1717 char *response = NULL; 1718 u_char echo = 0; 1719 u_int num_prompts, i; 1720 int r; 1721 1722 debug2("input_userauth_info_req"); 1723 1724 if (authctxt == NULL) 1725 fatal("input_userauth_info_req: no authentication context"); 1726 1727 authctxt->info_req_seen = 1; 1728 1729 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1730 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1731 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1732 goto out; 1733 if (strlen(name) > 0) 1734 logit("%s", name); 1735 if (strlen(inst) > 0) 1736 logit("%s", inst); 1737 1738 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1739 goto out; 1740 /* 1741 * Begin to build info response packet based on prompts requested. 1742 * We commit to providing the correct number of responses, so if 1743 * further on we run into a problem that prevents this, we have to 1744 * be sure and clean this up and send a correct error response. 1745 */ 1746 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1747 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1748 goto out; 1749 1750 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1751 for (i = 0; i < num_prompts; i++) { 1752 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1753 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1754 goto out; 1755 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1756 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1757 goto out; 1758 freezero(response, strlen(response)); 1759 free(prompt); 1760 response = prompt = NULL; 1761 } 1762 /* done with parsing incoming message. */ 1763 if ((r = sshpkt_get_end(ssh)) != 0 || 1764 (r = sshpkt_add_padding(ssh, 64)) != 0) 1765 goto out; 1766 r = sshpkt_send(ssh); 1767 out: 1768 if (response) 1769 freezero(response, strlen(response)); 1770 free(prompt); 1771 free(name); 1772 free(inst); 1773 free(lang); 1774 return r; 1775 } 1776 1777 static int 1778 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp, 1779 const u_char *data, size_t datalen) 1780 { 1781 struct sshbuf *b; 1782 struct stat st; 1783 pid_t pid; 1784 int i, r, to[2], from[2], status, sock = packet_get_connection_in(); 1785 u_char rversion = 0, version = 2; 1786 void (*osigchld)(int); 1787 1788 *sigp = NULL; 1789 *lenp = 0; 1790 1791 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1792 error("%s: not installed: %s", __func__, strerror(errno)); 1793 return -1; 1794 } 1795 if (fflush(stdout) != 0) { 1796 error("%s: fflush: %s", __func__, strerror(errno)); 1797 return -1; 1798 } 1799 if (pipe(to) < 0) { 1800 error("%s: pipe: %s", __func__, strerror(errno)); 1801 return -1; 1802 } 1803 if (pipe(from) < 0) { 1804 error("%s: pipe: %s", __func__, strerror(errno)); 1805 return -1; 1806 } 1807 if ((pid = fork()) < 0) { 1808 error("%s: fork: %s", __func__, strerror(errno)); 1809 return -1; 1810 } 1811 osigchld = signal(SIGCHLD, SIG_DFL); 1812 if (pid == 0) { 1813 /* keep the socket on exec */ 1814 fcntl(sock, F_SETFD, 0); 1815 close(from[0]); 1816 if (dup2(from[1], STDOUT_FILENO) < 0) 1817 fatal("%s: dup2: %s", __func__, strerror(errno)); 1818 close(to[1]); 1819 if (dup2(to[0], STDIN_FILENO) < 0) 1820 fatal("%s: dup2: %s", __func__, strerror(errno)); 1821 close(from[1]); 1822 close(to[0]); 1823 /* Close everything but stdio and the socket */ 1824 for (i = STDERR_FILENO + 1; i < sock; i++) 1825 close(i); 1826 closefrom(sock + 1); 1827 debug3("%s: [child] pid=%ld, exec %s", 1828 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1829 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1830 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1831 strerror(errno)); 1832 } 1833 close(from[1]); 1834 close(to[0]); 1835 1836 if ((b = sshbuf_new()) == NULL) 1837 fatal("%s: sshbuf_new failed", __func__); 1838 /* send # of sock, data to be signed */ 1839 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1840 (r = sshbuf_put_string(b, data, datalen)) != 0) 1841 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1842 if (ssh_msg_send(to[1], version, b) == -1) 1843 fatal("%s: couldn't send request", __func__); 1844 sshbuf_reset(b); 1845 r = ssh_msg_recv(from[0], b); 1846 close(from[0]); 1847 close(to[1]); 1848 if (r < 0) { 1849 error("%s: no reply", __func__); 1850 goto fail; 1851 } 1852 1853 errno = 0; 1854 while (waitpid(pid, &status, 0) < 0) { 1855 if (errno != EINTR) { 1856 error("%s: waitpid %ld: %s", 1857 __func__, (long)pid, strerror(errno)); 1858 goto fail; 1859 } 1860 } 1861 if (!WIFEXITED(status)) { 1862 error("%s: exited abnormally", __func__); 1863 goto fail; 1864 } 1865 if (WEXITSTATUS(status) != 0) { 1866 error("%s: exited with status %d", 1867 __func__, WEXITSTATUS(status)); 1868 goto fail; 1869 } 1870 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1871 error("%s: buffer error: %s", __func__, ssh_err(r)); 1872 goto fail; 1873 } 1874 if (rversion != version) { 1875 error("%s: bad version", __func__); 1876 goto fail; 1877 } 1878 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1879 error("%s: buffer error: %s", __func__, ssh_err(r)); 1880 fail: 1881 signal(SIGCHLD, osigchld); 1882 sshbuf_free(b); 1883 return -1; 1884 } 1885 signal(SIGCHLD, osigchld); 1886 sshbuf_free(b); 1887 1888 return 0; 1889 } 1890 1891 int 1892 userauth_hostbased(Authctxt *authctxt) 1893 { 1894 struct ssh *ssh = active_state; /* XXX */ 1895 struct sshkey *private = NULL; 1896 struct sshbuf *b = NULL; 1897 u_char *sig = NULL, *keyblob = NULL; 1898 char *fp = NULL, *chost = NULL, *lname = NULL; 1899 size_t siglen = 0, keylen = 0; 1900 int i, r, success = 0; 1901 1902 if (authctxt->ktypes == NULL) { 1903 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1904 authctxt->ktypes = authctxt->oktypes; 1905 } 1906 1907 /* 1908 * Work through each listed type pattern in HostbasedKeyTypes, 1909 * trying each hostkey that matches the type in turn. 1910 */ 1911 for (;;) { 1912 if (authctxt->active_ktype == NULL) 1913 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1914 if (authctxt->active_ktype == NULL || 1915 *authctxt->active_ktype == '\0') 1916 break; 1917 debug3("%s: trying key type %s", __func__, 1918 authctxt->active_ktype); 1919 1920 /* check for a useful key */ 1921 private = NULL; 1922 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1923 if (authctxt->sensitive->keys[i] == NULL || 1924 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1925 continue; 1926 if (match_pattern_list( 1927 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1928 authctxt->active_ktype, 0) != 1) 1929 continue; 1930 /* we take and free the key */ 1931 private = authctxt->sensitive->keys[i]; 1932 authctxt->sensitive->keys[i] = NULL; 1933 break; 1934 } 1935 /* Found one */ 1936 if (private != NULL) 1937 break; 1938 /* No more keys of this type; advance */ 1939 authctxt->active_ktype = NULL; 1940 } 1941 if (private == NULL) { 1942 free(authctxt->oktypes); 1943 authctxt->oktypes = authctxt->ktypes = NULL; 1944 authctxt->active_ktype = NULL; 1945 debug("No more client hostkeys for hostbased authentication."); 1946 goto out; 1947 } 1948 1949 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1950 SSH_FP_DEFAULT)) == NULL) { 1951 error("%s: sshkey_fingerprint failed", __func__); 1952 goto out; 1953 } 1954 debug("%s: trying hostkey %s %s", 1955 __func__, sshkey_ssh_name(private), fp); 1956 1957 /* figure out a name for the client host */ 1958 if ((lname = get_local_name(packet_get_connection_in())) == NULL) { 1959 error("%s: cannot get local ipaddr/name", __func__); 1960 goto out; 1961 } 1962 1963 /* XXX sshbuf_put_stringf? */ 1964 xasprintf(&chost, "%s.", lname); 1965 debug2("%s: chost %s", __func__, chost); 1966 1967 /* construct data */ 1968 if ((b = sshbuf_new()) == NULL) { 1969 error("%s: sshbuf_new failed", __func__); 1970 goto out; 1971 } 1972 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 1973 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 1974 goto out; 1975 } 1976 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 1977 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1978 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1979 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1980 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1981 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 1982 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 1983 (r = sshbuf_put_cstring(b, chost)) != 0 || 1984 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 1985 error("%s: buffer error: %s", __func__, ssh_err(r)); 1986 goto out; 1987 } 1988 1989 #ifdef DEBUG_PK 1990 sshbuf_dump(b, stderr); 1991 #endif 1992 r = ssh_keysign(private, &sig, &siglen, 1993 sshbuf_ptr(b), sshbuf_len(b)); 1994 if (r != 0) { 1995 error("sign using hostkey %s %s failed", 1996 sshkey_ssh_name(private), fp); 1997 goto out; 1998 } 1999 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2000 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2001 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2002 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2003 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2004 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2005 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2006 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2007 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2008 (r = sshpkt_send(ssh)) != 0) { 2009 error("%s: packet error: %s", __func__, ssh_err(r)); 2010 goto out; 2011 } 2012 success = 1; 2013 2014 out: 2015 if (sig != NULL) 2016 freezero(sig, siglen); 2017 free(keyblob); 2018 free(lname); 2019 free(fp); 2020 free(chost); 2021 sshkey_free(private); 2022 sshbuf_free(b); 2023 2024 return success; 2025 } 2026 2027 /* find auth method */ 2028 2029 /* 2030 * given auth method name, if configurable options permit this method fill 2031 * in auth_ident field and return true, otherwise return false. 2032 */ 2033 static int 2034 authmethod_is_enabled(Authmethod *method) 2035 { 2036 if (method == NULL) 2037 return 0; 2038 /* return false if options indicate this method is disabled */ 2039 if (method->enabled == NULL || *method->enabled == 0) 2040 return 0; 2041 /* return false if batch mode is enabled but method needs interactive mode */ 2042 if (method->batch_flag != NULL && *method->batch_flag != 0) 2043 return 0; 2044 return 1; 2045 } 2046 2047 static Authmethod * 2048 authmethod_lookup(const char *name) 2049 { 2050 Authmethod *method = NULL; 2051 if (name != NULL) 2052 for (method = authmethods; method->name != NULL; method++) 2053 if (strcmp(name, method->name) == 0) 2054 return method; 2055 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2056 return NULL; 2057 } 2058 2059 /* XXX internal state */ 2060 static Authmethod *current = NULL; 2061 static char *supported = NULL; 2062 static char *preferred = NULL; 2063 2064 /* 2065 * Given the authentication method list sent by the server, return the 2066 * next method we should try. If the server initially sends a nil list, 2067 * use a built-in default list. 2068 */ 2069 static Authmethod * 2070 authmethod_get(char *authlist) 2071 { 2072 char *name = NULL; 2073 u_int next; 2074 2075 /* Use a suitable default if we're passed a nil list. */ 2076 if (authlist == NULL || strlen(authlist) == 0) 2077 authlist = options.preferred_authentications; 2078 2079 if (supported == NULL || strcmp(authlist, supported) != 0) { 2080 debug3("start over, passed a different list %s", authlist); 2081 free(supported); 2082 supported = xstrdup(authlist); 2083 preferred = options.preferred_authentications; 2084 debug3("preferred %s", preferred); 2085 current = NULL; 2086 } else if (current != NULL && authmethod_is_enabled(current)) 2087 return current; 2088 2089 for (;;) { 2090 if ((name = match_list(preferred, supported, &next)) == NULL) { 2091 debug("No more authentication methods to try."); 2092 current = NULL; 2093 return NULL; 2094 } 2095 preferred += next; 2096 debug3("authmethod_lookup %s", name); 2097 debug3("remaining preferred: %s", preferred); 2098 if ((current = authmethod_lookup(name)) != NULL && 2099 authmethod_is_enabled(current)) { 2100 debug3("authmethod_is_enabled %s", name); 2101 debug("Next authentication method: %s", name); 2102 free(name); 2103 return current; 2104 } 2105 free(name); 2106 } 2107 } 2108 2109 static char * 2110 authmethods_get(void) 2111 { 2112 Authmethod *method = NULL; 2113 struct sshbuf *b; 2114 char *list; 2115 int r; 2116 2117 if ((b = sshbuf_new()) == NULL) 2118 fatal("%s: sshbuf_new failed", __func__); 2119 for (method = authmethods; method->name != NULL; method++) { 2120 if (authmethod_is_enabled(method)) { 2121 if ((r = sshbuf_putf(b, "%s%s", 2122 sshbuf_len(b) ? "," : "", method->name)) != 0) 2123 fatal("%s: buffer error: %s", 2124 __func__, ssh_err(r)); 2125 } 2126 } 2127 if ((list = sshbuf_dup_string(b)) == NULL) 2128 fatal("%s: sshbuf_dup_string failed", __func__); 2129 sshbuf_free(b); 2130 return list; 2131 } 2132