1 /* $OpenBSD: sshconnect2.c,v 1.303 2019/02/12 23:53:10 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(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 159 { 160 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 161 char *s, *all_key; 162 int r; 163 164 xxx_host = host; 165 xxx_hostaddr = hostaddr; 166 167 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 168 fatal("%s: kex_names_cat", __func__); 169 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 170 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 171 compat_cipher_proposal(options.ciphers); 172 myproposal[PROPOSAL_ENC_ALGS_STOC] = 173 compat_cipher_proposal(options.ciphers); 174 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 175 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 176 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 177 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 178 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 179 if (options.hostkeyalgorithms != NULL) { 180 all_key = sshkey_alg_list(0, 0, 1, ','); 181 if (kex_assemble_names(&options.hostkeyalgorithms, 182 KEX_DEFAULT_PK_ALG, all_key) != 0) 183 fatal("%s: kex_assemble_namelist", __func__); 184 free(all_key); 185 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 186 compat_pkalg_proposal(options.hostkeyalgorithms); 187 } else { 188 /* Enforce default */ 189 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 190 /* Prefer algorithms that we already have keys for */ 191 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 192 compat_pkalg_proposal( 193 order_hostkeyalgs(host, hostaddr, port)); 194 } 195 196 if (options.rekey_limit || options.rekey_interval) 197 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 198 options.rekey_interval); 199 200 /* start key exchange */ 201 if ((r = kex_setup(ssh, myproposal)) != 0) 202 fatal("kex_setup: %s", ssh_err(r)); 203 #ifdef WITH_OPENSSL 204 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 205 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 206 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 207 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 208 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 209 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 210 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 211 # ifdef OPENSSL_HAS_ECC 212 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 213 # endif 214 #endif 215 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 216 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 217 ssh->kex->verify_host_key=&verify_host_key_callback; 218 219 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 220 221 /* remove ext-info from the KEX proposals for rekeying */ 222 myproposal[PROPOSAL_KEX_ALGS] = 223 compat_kex_proposal(options.kex_algorithms); 224 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 225 fatal("kex_prop2buf: %s", ssh_err(r)); 226 227 session_id2 = ssh->kex->session_id; 228 session_id2_len = ssh->kex->session_id_len; 229 230 #ifdef DEBUG_KEXDH 231 /* send 1st encrypted/maced/compressed message */ 232 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 233 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 234 (r = sshpkt_send(ssh)) != 0 || 235 (r = ssh_packet_write_wait(ssh)) != 0) 236 fatal("%s: %s", __func__, ssh_err(r)); 237 #endif 238 } 239 240 /* 241 * Authenticate user 242 */ 243 244 typedef struct cauthctxt Authctxt; 245 typedef struct cauthmethod Authmethod; 246 typedef struct identity Identity; 247 typedef struct idlist Idlist; 248 249 struct identity { 250 TAILQ_ENTRY(identity) next; 251 int agent_fd; /* >=0 if agent supports key */ 252 struct sshkey *key; /* public/private key */ 253 char *filename; /* comment for agent-only keys */ 254 int tried; 255 int isprivate; /* key points to the private key */ 256 int userprovided; 257 }; 258 TAILQ_HEAD(idlist, identity); 259 260 struct cauthctxt { 261 const char *server_user; 262 const char *local_user; 263 const char *host; 264 const char *service; 265 struct cauthmethod *method; 266 sig_atomic_t success; 267 char *authlist; 268 #ifdef GSSAPI 269 /* gssapi */ 270 gss_OID_set gss_supported_mechs; 271 u_int mech_tried; 272 #endif 273 /* pubkey */ 274 struct idlist keys; 275 int agent_fd; 276 /* hostbased */ 277 Sensitive *sensitive; 278 char *oktypes, *ktypes; 279 const char *active_ktype; 280 /* kbd-interactive */ 281 int info_req_seen; 282 int attempt_kbdint; 283 /* password */ 284 int attempt_passwd; 285 /* generic */ 286 void *methoddata; 287 }; 288 289 struct cauthmethod { 290 char *name; /* string to compare against server's list */ 291 int (*userauth)(struct ssh *ssh); 292 void (*cleanup)(struct ssh *ssh); 293 int *enabled; /* flag in option struct that enables method */ 294 int *batch_flag; /* flag in option struct that disables method */ 295 }; 296 297 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 298 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 299 static int input_userauth_success(int, u_int32_t, struct ssh *); 300 static int input_userauth_failure(int, u_int32_t, struct ssh *); 301 static int input_userauth_banner(int, u_int32_t, struct ssh *); 302 static int input_userauth_error(int, u_int32_t, struct ssh *); 303 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 304 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 305 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 306 307 static int userauth_none(struct ssh *); 308 static int userauth_pubkey(struct ssh *); 309 static int userauth_passwd(struct ssh *); 310 static int userauth_kbdint(struct ssh *); 311 static int userauth_hostbased(struct ssh *); 312 313 #ifdef GSSAPI 314 static int userauth_gssapi(struct ssh *); 315 static void userauth_gssapi_cleanup(struct ssh *); 316 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 317 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 318 static int input_gssapi_error(int, u_int32_t, struct ssh *); 319 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 320 #endif 321 322 void userauth(struct ssh *, char *); 323 324 static void pubkey_cleanup(struct ssh *); 325 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 326 static void pubkey_prepare(Authctxt *); 327 static void pubkey_reset(Authctxt *); 328 static struct sshkey *load_identity_file(Identity *); 329 330 static Authmethod *authmethod_get(char *authlist); 331 static Authmethod *authmethod_lookup(const char *name); 332 static char *authmethods_get(void); 333 334 Authmethod authmethods[] = { 335 #ifdef GSSAPI 336 {"gssapi-with-mic", 337 userauth_gssapi, 338 userauth_gssapi_cleanup, 339 &options.gss_authentication, 340 NULL}, 341 #endif 342 {"hostbased", 343 userauth_hostbased, 344 NULL, 345 &options.hostbased_authentication, 346 NULL}, 347 {"publickey", 348 userauth_pubkey, 349 NULL, 350 &options.pubkey_authentication, 351 NULL}, 352 {"keyboard-interactive", 353 userauth_kbdint, 354 NULL, 355 &options.kbd_interactive_authentication, 356 &options.batch_mode}, 357 {"password", 358 userauth_passwd, 359 NULL, 360 &options.password_authentication, 361 &options.batch_mode}, 362 {"none", 363 userauth_none, 364 NULL, 365 NULL, 366 NULL}, 367 {NULL, NULL, NULL, NULL, NULL} 368 }; 369 370 void 371 ssh_userauth2(struct ssh *ssh, const char *local_user, 372 const char *server_user, char *host, Sensitive *sensitive) 373 { 374 Authctxt authctxt; 375 int r; 376 377 if (options.challenge_response_authentication) 378 options.kbd_interactive_authentication = 1; 379 if (options.preferred_authentications == NULL) 380 options.preferred_authentications = authmethods_get(); 381 382 /* setup authentication context */ 383 memset(&authctxt, 0, sizeof(authctxt)); 384 authctxt.server_user = server_user; 385 authctxt.local_user = local_user; 386 authctxt.host = host; 387 authctxt.service = "ssh-connection"; /* service name */ 388 authctxt.success = 0; 389 authctxt.method = authmethod_lookup("none"); 390 authctxt.authlist = NULL; 391 authctxt.methoddata = NULL; 392 authctxt.sensitive = sensitive; 393 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 394 authctxt.info_req_seen = 0; 395 authctxt.attempt_kbdint = 0; 396 authctxt.attempt_passwd = 0; 397 #if GSSAPI 398 authctxt.gss_supported_mechs = NULL; 399 authctxt.mech_tried = 0; 400 #endif 401 authctxt.agent_fd = -1; 402 pubkey_prepare(&authctxt); 403 if (authctxt.method == NULL) { 404 fatal("%s: internal error: cannot send userauth none request", 405 __func__); 406 } 407 408 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 409 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 410 (r = sshpkt_send(ssh)) != 0) 411 fatal("%s: %s", __func__, ssh_err(r)); 412 413 ssh->authctxt = &authctxt; 414 ssh_dispatch_init(ssh, &input_userauth_error); 415 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 416 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 417 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 418 pubkey_cleanup(ssh); 419 ssh->authctxt = NULL; 420 421 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 422 423 if (!authctxt.success) 424 fatal("Authentication failed."); 425 debug("Authentication succeeded (%s).", authctxt.method->name); 426 } 427 428 /* ARGSUSED */ 429 static int 430 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 431 { 432 int r; 433 434 if (ssh_packet_remaining(ssh) > 0) { 435 char *reply; 436 437 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 438 goto out; 439 debug2("service_accept: %s", reply); 440 free(reply); 441 } else { 442 debug2("buggy server: service_accept w/o service"); 443 } 444 if ((r = sshpkt_get_end(ssh)) != 0) 445 goto out; 446 debug("SSH2_MSG_SERVICE_ACCEPT received"); 447 448 /* initial userauth request */ 449 userauth_none(ssh); 450 451 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 452 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 453 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 454 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 455 r = 0; 456 out: 457 return r; 458 } 459 460 /* ARGSUSED */ 461 static int 462 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 463 { 464 return kex_input_ext_info(type, seqnr, ssh); 465 } 466 467 void 468 userauth(struct ssh *ssh, char *authlist) 469 { 470 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 471 472 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 473 authctxt->method->cleanup(ssh); 474 475 free(authctxt->methoddata); 476 authctxt->methoddata = NULL; 477 if (authlist == NULL) { 478 authlist = authctxt->authlist; 479 } else { 480 free(authctxt->authlist); 481 authctxt->authlist = authlist; 482 } 483 for (;;) { 484 Authmethod *method = authmethod_get(authlist); 485 if (method == NULL) 486 fatal("%s@%s: Permission denied (%s).", 487 authctxt->server_user, authctxt->host, authlist); 488 authctxt->method = method; 489 490 /* reset the per method handler */ 491 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 492 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 493 494 /* and try new method */ 495 if (method->userauth(ssh) != 0) { 496 debug2("we sent a %s packet, wait for reply", method->name); 497 break; 498 } else { 499 debug2("we did not send a packet, disable method"); 500 method->enabled = NULL; 501 } 502 } 503 } 504 505 /* ARGSUSED */ 506 static int 507 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 508 { 509 fatal("%s: bad message during authentication: type %d", __func__, type); 510 return 0; 511 } 512 513 /* ARGSUSED */ 514 static int 515 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 516 { 517 char *msg = NULL; 518 size_t len; 519 int r; 520 521 debug3("%s", __func__); 522 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 523 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 524 goto out; 525 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 526 fmprintf(stderr, "%s", msg); 527 r = 0; 528 out: 529 free(msg); 530 return r; 531 } 532 533 /* ARGSUSED */ 534 static int 535 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 536 { 537 Authctxt *authctxt = ssh->authctxt; 538 539 if (authctxt == NULL) 540 fatal("%s: no authentication context", __func__); 541 free(authctxt->authlist); 542 authctxt->authlist = NULL; 543 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 544 authctxt->method->cleanup(ssh); 545 free(authctxt->methoddata); 546 authctxt->methoddata = NULL; 547 authctxt->success = 1; /* break out */ 548 return 0; 549 } 550 551 #if 0 552 static int 553 input_userauth_success_unexpected(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__); 559 560 fatal("Unexpected authentication success during %s.", 561 authctxt->method->name); 562 return 0; 563 } 564 #endif 565 566 /* ARGSUSED */ 567 static int 568 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 569 { 570 Authctxt *authctxt = ssh->authctxt; 571 char *authlist = NULL; 572 u_char partial; 573 int r; 574 575 if (authctxt == NULL) 576 fatal("input_userauth_failure: no authentication context"); 577 578 if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 || 579 (r = sshpkt_get_u8(ssh, &partial)) != 0 || 580 (r = sshpkt_get_end(ssh)) != 0) 581 goto out; 582 583 if (partial != 0) { 584 verbose("Authenticated with partial success."); 585 /* reset state */ 586 pubkey_reset(authctxt); 587 } 588 debug("Authentications that can continue: %s", authlist); 589 590 userauth(ssh, authlist); 591 authlist = NULL; 592 out: 593 free(authlist); 594 return 0; 595 } 596 597 /* 598 * Format an identity for logging including filename, key type, fingerprint 599 * and location (agent, etc.). Caller must free. 600 */ 601 static char * 602 format_identity(Identity *id) 603 { 604 char *fp = NULL, *ret = NULL; 605 606 if (id->key != NULL) { 607 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 608 SSH_FP_DEFAULT); 609 } 610 xasprintf(&ret, "%s %s%s%s%s%s%s", 611 id->filename, 612 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 613 fp ? fp : "", 614 id->userprovided ? " explicit" : "", 615 (id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "", 616 id->agent_fd != -1 ? " agent" : ""); 617 free(fp); 618 return ret; 619 } 620 621 /* ARGSUSED */ 622 static int 623 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 624 { 625 Authctxt *authctxt = ssh->authctxt; 626 struct sshkey *key = NULL; 627 Identity *id = NULL; 628 int pktype, found = 0, sent = 0; 629 size_t blen; 630 char *pkalg = NULL, *fp = NULL, *ident = NULL; 631 u_char *pkblob = NULL; 632 int r; 633 634 if (authctxt == NULL) 635 fatal("input_userauth_pk_ok: no authentication context"); 636 637 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 638 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 639 (r = sshpkt_get_end(ssh)) != 0) 640 goto done; 641 642 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 643 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 644 goto done; 645 } 646 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 647 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 648 goto done; 649 } 650 if (key->type != pktype) { 651 error("input_userauth_pk_ok: type mismatch " 652 "for decoded key (received %d, expected %d)", 653 key->type, pktype); 654 goto done; 655 } 656 657 /* 658 * search keys in the reverse order, because last candidate has been 659 * moved to the end of the queue. this also avoids confusion by 660 * duplicate keys 661 */ 662 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 663 if (sshkey_equal(key, id->key)) { 664 found = 1; 665 break; 666 } 667 } 668 if (!found || id == NULL) { 669 fp = sshkey_fingerprint(key, options.fingerprint_hash, 670 SSH_FP_DEFAULT); 671 error("%s: server replied with unknown key: %s %s", __func__, 672 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 673 goto done; 674 } 675 ident = format_identity(id); 676 debug("Server accepts key: %s", ident); 677 sent = sign_and_send_pubkey(ssh, id); 678 r = 0; 679 done: 680 sshkey_free(key); 681 free(ident); 682 free(fp); 683 free(pkalg); 684 free(pkblob); 685 686 /* try another method if we did not send a packet */ 687 if (r == 0 && sent == 0) 688 userauth(ssh, NULL); 689 return r; 690 } 691 692 #ifdef GSSAPI 693 static int 694 userauth_gssapi(struct ssh *ssh) 695 { 696 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 697 Gssctxt *gssctxt = NULL; 698 OM_uint32 min; 699 int r, ok = 0; 700 gss_OID mech = NULL; 701 702 /* Try one GSSAPI method at a time, rather than sending them all at 703 * once. */ 704 705 if (authctxt->gss_supported_mechs == NULL) 706 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 707 708 /* Check to see whether the mechanism is usable before we offer it */ 709 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 710 !ok) { 711 mech = &authctxt->gss_supported_mechs-> 712 elements[authctxt->mech_tried]; 713 /* My DER encoding requires length<128 */ 714 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 715 mech, authctxt->host)) { 716 ok = 1; /* Mechanism works */ 717 } else { 718 authctxt->mech_tried++; 719 } 720 } 721 722 if (!ok || mech == NULL) 723 return 0; 724 725 authctxt->methoddata=(void *)gssctxt; 726 727 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 728 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 729 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 730 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 731 (r = sshpkt_put_u32(ssh, 1)) != 0 || 732 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 733 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 734 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 735 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 736 (r = sshpkt_send(ssh)) != 0) 737 fatal("%s: %s", __func__, ssh_err(r)); 738 739 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 740 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 741 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 742 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 743 744 authctxt->mech_tried++; /* Move along to next candidate */ 745 746 return 1; 747 } 748 749 static void 750 userauth_gssapi_cleanup(struct ssh *ssh) 751 { 752 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 753 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 754 755 ssh_gssapi_delete_ctx(&gssctxt); 756 authctxt->methoddata = NULL; 757 758 free(authctxt->gss_supported_mechs); 759 authctxt->gss_supported_mechs = NULL; 760 } 761 762 static OM_uint32 763 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 764 { 765 Authctxt *authctxt = ssh->authctxt; 766 Gssctxt *gssctxt = authctxt->methoddata; 767 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 768 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 769 gss_buffer_desc gssbuf; 770 OM_uint32 status, ms, flags; 771 int r; 772 773 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 774 recv_tok, &send_tok, &flags); 775 776 if (send_tok.length > 0) { 777 u_char type = GSS_ERROR(status) ? 778 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 779 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 780 781 if ((r = sshpkt_start(ssh, type)) != 0 || 782 (r = sshpkt_put_string(ssh, send_tok.value, 783 send_tok.length)) != 0 || 784 (r = sshpkt_send(ssh)) != 0) 785 fatal("%s: %s", __func__, ssh_err(r)); 786 787 gss_release_buffer(&ms, &send_tok); 788 } 789 790 if (status == GSS_S_COMPLETE) { 791 /* send either complete or MIC, depending on mechanism */ 792 if (!(flags & GSS_C_INTEG_FLAG)) { 793 if ((r = sshpkt_start(ssh, 794 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 795 (r = sshpkt_send(ssh)) != 0) 796 fatal("%s: %s", __func__, ssh_err(r)); 797 } else { 798 struct sshbuf *b; 799 800 if ((b = sshbuf_new()) == NULL) 801 fatal("%s: sshbuf_new failed", __func__); 802 ssh_gssapi_buildmic(b, authctxt->server_user, 803 authctxt->service, "gssapi-with-mic"); 804 805 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 806 fatal("%s: sshbuf_mutable_ptr failed", __func__); 807 gssbuf.length = sshbuf_len(b); 808 809 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 810 811 if (!GSS_ERROR(status)) { 812 if ((r = sshpkt_start(ssh, 813 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 814 (r = sshpkt_put_string(ssh, mic.value, 815 mic.length)) != 0 || 816 (r = sshpkt_send(ssh)) != 0) 817 fatal("%s: %s", __func__, ssh_err(r)); 818 } 819 820 sshbuf_free(b); 821 gss_release_buffer(&ms, &mic); 822 } 823 } 824 825 return status; 826 } 827 828 /* ARGSUSED */ 829 static int 830 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 831 { 832 Authctxt *authctxt = ssh->authctxt; 833 Gssctxt *gssctxt; 834 size_t oidlen; 835 u_char *oidv = NULL; 836 int r; 837 838 if (authctxt == NULL) 839 fatal("input_gssapi_response: no authentication context"); 840 gssctxt = authctxt->methoddata; 841 842 /* Setup our OID */ 843 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 844 goto done; 845 846 if (oidlen <= 2 || 847 oidv[0] != SSH_GSS_OIDTYPE || 848 oidv[1] != oidlen - 2) { 849 debug("Badly encoded mechanism OID received"); 850 userauth(ssh, NULL); 851 goto ok; 852 } 853 854 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 855 fatal("Server returned different OID than expected"); 856 857 if ((r = sshpkt_get_end(ssh)) != 0) 858 goto done; 859 860 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 861 /* Start again with next method on list */ 862 debug("Trying to start again"); 863 userauth(ssh, NULL); 864 goto ok; 865 } 866 ok: 867 r = 0; 868 done: 869 free(oidv); 870 return r; 871 } 872 873 /* ARGSUSED */ 874 static int 875 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 876 { 877 Authctxt *authctxt = ssh->authctxt; 878 gss_buffer_desc recv_tok; 879 u_char *p = NULL; 880 size_t len; 881 OM_uint32 status; 882 int r; 883 884 if (authctxt == NULL) 885 fatal("input_gssapi_response: no authentication context"); 886 887 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 888 (r = sshpkt_get_end(ssh)) != 0) 889 goto out; 890 891 recv_tok.value = p; 892 recv_tok.length = len; 893 status = process_gssapi_token(ssh, &recv_tok); 894 895 /* Start again with the next method in the list */ 896 if (GSS_ERROR(status)) { 897 userauth(ssh, NULL); 898 /* ok */ 899 } 900 r = 0; 901 out: 902 free(p); 903 return r; 904 } 905 906 /* ARGSUSED */ 907 static int 908 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 909 { 910 Authctxt *authctxt = ssh->authctxt; 911 Gssctxt *gssctxt; 912 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 913 gss_buffer_desc recv_tok; 914 OM_uint32 ms; 915 u_char *p = NULL; 916 size_t len; 917 int r; 918 919 if (authctxt == NULL) 920 fatal("input_gssapi_response: no authentication context"); 921 gssctxt = authctxt->methoddata; 922 923 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 924 (r = sshpkt_get_end(ssh)) != 0) { 925 free(p); 926 return r; 927 } 928 929 /* Stick it into GSSAPI and see what it says */ 930 recv_tok.value = p; 931 recv_tok.length = len; 932 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 933 &recv_tok, &send_tok, NULL); 934 free(p); 935 gss_release_buffer(&ms, &send_tok); 936 937 /* Server will be returning a failed packet after this one */ 938 return 0; 939 } 940 941 /* ARGSUSED */ 942 static int 943 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 944 { 945 char *msg = NULL; 946 char *lang = NULL; 947 int r; 948 949 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 950 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 951 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 952 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 953 goto out; 954 r = sshpkt_get_end(ssh); 955 debug("Server GSSAPI Error:\n%s", msg); 956 out: 957 free(msg); 958 free(lang); 959 return r; 960 } 961 #endif /* GSSAPI */ 962 963 static int 964 userauth_none(struct ssh *ssh) 965 { 966 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 967 int r; 968 969 /* initial userauth request */ 970 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 971 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 972 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 973 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 974 (r = sshpkt_send(ssh)) != 0) 975 fatal("%s: %s", __func__, ssh_err(r)); 976 return 1; 977 } 978 979 static int 980 userauth_passwd(struct ssh *ssh) 981 { 982 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 983 char *password, *prompt = NULL; 984 const char *host = options.host_key_alias ? options.host_key_alias : 985 authctxt->host; 986 int r; 987 988 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 989 return 0; 990 991 if (authctxt->attempt_passwd != 1) 992 error("Permission denied, please try again."); 993 994 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 995 password = read_passphrase(prompt, 0); 996 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 997 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 998 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 999 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1000 (r = sshpkt_put_u8(ssh, 0)) != 0 || 1001 (r = sshpkt_put_cstring(ssh, password)) != 0 || 1002 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1003 (r = sshpkt_send(ssh)) != 0) 1004 fatal("%s: %s", __func__, ssh_err(r)); 1005 1006 free(prompt); 1007 if (password != NULL) 1008 freezero(password, strlen(password)); 1009 1010 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1011 &input_userauth_passwd_changereq); 1012 1013 return 1; 1014 } 1015 1016 /* 1017 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1018 */ 1019 /* ARGSUSED */ 1020 static int 1021 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1022 { 1023 Authctxt *authctxt = ssh->authctxt; 1024 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1025 char prompt[256]; 1026 const char *host; 1027 int r; 1028 1029 debug2("input_userauth_passwd_changereq"); 1030 1031 if (authctxt == NULL) 1032 fatal("input_userauth_passwd_changereq: " 1033 "no authentication context"); 1034 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1035 1036 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1037 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1038 goto out; 1039 if (strlen(info) > 0) 1040 logit("%s", info); 1041 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1042 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1043 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1044 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1045 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1046 goto out; 1047 1048 snprintf(prompt, sizeof(prompt), 1049 "Enter %.30s@%.128s's old password: ", 1050 authctxt->server_user, host); 1051 password = read_passphrase(prompt, 0); 1052 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1053 goto out; 1054 1055 freezero(password, strlen(password)); 1056 password = NULL; 1057 while (password == NULL) { 1058 snprintf(prompt, sizeof(prompt), 1059 "Enter %.30s@%.128s's new password: ", 1060 authctxt->server_user, host); 1061 password = read_passphrase(prompt, RP_ALLOW_EOF); 1062 if (password == NULL) { 1063 /* bail out */ 1064 r = 0; 1065 goto out; 1066 } 1067 snprintf(prompt, sizeof(prompt), 1068 "Retype %.30s@%.128s's new password: ", 1069 authctxt->server_user, host); 1070 retype = read_passphrase(prompt, 0); 1071 if (strcmp(password, retype) != 0) { 1072 freezero(password, strlen(password)); 1073 logit("Mismatch; try again, EOF to quit."); 1074 password = NULL; 1075 } 1076 freezero(retype, strlen(retype)); 1077 } 1078 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1079 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1080 (r = sshpkt_send(ssh)) != 0) 1081 goto out; 1082 1083 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1084 &input_userauth_passwd_changereq); 1085 r = 0; 1086 out: 1087 if (password) 1088 freezero(password, strlen(password)); 1089 free(info); 1090 free(lang); 1091 return r; 1092 } 1093 1094 /* 1095 * Select an algorithm for publickey signatures. 1096 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1097 * 1098 * Call with ssh==NULL to ignore server-sig-algs extension list and 1099 * only attempt with the key's base signature type. 1100 */ 1101 static char * 1102 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1103 { 1104 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1105 1106 /* 1107 * The signature algorithm will only differ from the key algorithm 1108 * for RSA keys/certs and when the server advertises support for 1109 * newer (SHA2) algorithms. 1110 */ 1111 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1112 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1113 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1114 /* Filter base key signature alg against our configuration */ 1115 return match_list(sshkey_ssh_name(key), 1116 options.pubkey_key_types, NULL); 1117 } 1118 1119 /* 1120 * For RSA keys/certs, since these might have a different sig type: 1121 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1122 * that also appears in the supported signature algorithms list from 1123 * the server. 1124 */ 1125 oallowed = allowed = xstrdup(options.pubkey_key_types); 1126 while ((cp = strsep(&allowed, ",")) != NULL) { 1127 if (sshkey_type_from_name(cp) != key->type) 1128 continue; 1129 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1130 if (tmp != NULL) 1131 alg = xstrdup(cp); 1132 free(tmp); 1133 if (alg != NULL) 1134 break; 1135 } 1136 free(oallowed); 1137 return alg; 1138 } 1139 1140 static int 1141 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1142 const u_char *data, size_t datalen, u_int compat, const char *alg) 1143 { 1144 struct sshkey *prv; 1145 int r; 1146 1147 /* The agent supports this key. */ 1148 if (id->key != NULL && id->agent_fd != -1) { 1149 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1150 data, datalen, alg, compat); 1151 } 1152 1153 /* 1154 * We have already loaded the private key or the private key is 1155 * stored in external hardware. 1156 */ 1157 if (id->key != NULL && 1158 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1159 if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen, 1160 alg, compat)) != 0) 1161 return r; 1162 /* 1163 * PKCS#11 tokens may not support all signature algorithms, 1164 * so check what we get back. 1165 */ 1166 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) 1167 return r; 1168 return 0; 1169 } 1170 1171 /* Load the private key from the file. */ 1172 if ((prv = load_identity_file(id)) == NULL) 1173 return SSH_ERR_KEY_NOT_FOUND; 1174 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1175 error("%s: private key %s contents do not match public", 1176 __func__, id->filename); 1177 return SSH_ERR_KEY_NOT_FOUND; 1178 } 1179 r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1180 sshkey_free(prv); 1181 return r; 1182 } 1183 1184 static int 1185 id_filename_matches(Identity *id, Identity *private_id) 1186 { 1187 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1188 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1189 size_t i, slen; 1190 1191 if (strcmp(id->filename, private_id->filename) == 0) 1192 return 1; 1193 for (i = 0; suffixes[i]; i++) { 1194 slen = strlen(suffixes[i]); 1195 if (len > slen && plen == len - slen && 1196 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1197 memcmp(id->filename, private_id->filename, plen) == 0) 1198 return 1; 1199 } 1200 return 0; 1201 } 1202 1203 static int 1204 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1205 { 1206 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1207 struct sshbuf *b = NULL; 1208 Identity *private_id, *sign_id = NULL; 1209 u_char *signature = NULL; 1210 size_t slen = 0, skip = 0; 1211 int r, fallback_sigtype, sent = 0; 1212 char *alg = NULL, *fp = NULL; 1213 const char *loc = ""; 1214 1215 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1216 SSH_FP_DEFAULT)) == NULL) 1217 return 0; 1218 1219 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1220 1221 /* 1222 * If the key is an certificate, try to find a matching private key 1223 * and use it to complete the signature. 1224 * If no such private key exists, fall back to trying the certificate 1225 * key itself in case it has a private half already loaded. 1226 * This will try to set sign_id to the private key that will perform 1227 * the signature. 1228 */ 1229 if (sshkey_is_cert(id->key)) { 1230 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1231 if (sshkey_equal_public(id->key, private_id->key) && 1232 id->key->type != private_id->key->type) { 1233 sign_id = private_id; 1234 break; 1235 } 1236 } 1237 /* 1238 * Exact key matches are preferred, but also allow 1239 * filename matches for non-PKCS#11/agent keys that 1240 * didn't load public keys. This supports the case 1241 * of keeping just a private key file and public 1242 * certificate on disk. 1243 */ 1244 if (sign_id == NULL && 1245 !id->isprivate && id->agent_fd == -1 && 1246 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1247 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1248 if (private_id->key == NULL && 1249 id_filename_matches(id, private_id)) { 1250 sign_id = private_id; 1251 break; 1252 } 1253 } 1254 } 1255 if (sign_id != NULL) { 1256 debug2("%s: using private key \"%s\"%s for " 1257 "certificate", __func__, id->filename, 1258 id->agent_fd != -1 ? " from agent" : ""); 1259 } else { 1260 debug("%s: no separate private key for certificate " 1261 "\"%s\"", __func__, id->filename); 1262 } 1263 } 1264 1265 /* 1266 * If the above didn't select another identity to do the signing 1267 * then default to the one we started with. 1268 */ 1269 if (sign_id == NULL) 1270 sign_id = id; 1271 1272 /* assemble and sign data */ 1273 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1274 free(alg); 1275 slen = 0; 1276 signature = NULL; 1277 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1278 id->key)) == NULL) { 1279 error("%s: no mutual signature supported", __func__); 1280 goto out; 1281 } 1282 debug3("%s: signing using %s", __func__, alg); 1283 1284 sshbuf_free(b); 1285 if ((b = sshbuf_new()) == NULL) 1286 fatal("%s: sshbuf_new failed", __func__); 1287 if (datafellows & SSH_OLD_SESSIONID) { 1288 if ((r = sshbuf_put(b, session_id2, 1289 session_id2_len)) != 0) { 1290 fatal("%s: sshbuf_put: %s", 1291 __func__, ssh_err(r)); 1292 } 1293 } else { 1294 if ((r = sshbuf_put_string(b, session_id2, 1295 session_id2_len)) != 0) { 1296 fatal("%s: sshbuf_put_string: %s", 1297 __func__, ssh_err(r)); 1298 } 1299 } 1300 skip = sshbuf_len(b); 1301 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1302 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1303 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1304 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1305 (r = sshbuf_put_u8(b, 1)) != 0 || 1306 (r = sshbuf_put_cstring(b, alg)) != 0 || 1307 (r = sshkey_puts(id->key, b)) != 0) { 1308 fatal("%s: assemble signed data: %s", 1309 __func__, ssh_err(r)); 1310 } 1311 1312 /* generate signature */ 1313 r = identity_sign(sign_id, &signature, &slen, 1314 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1315 if (r == 0) 1316 break; 1317 else if (r == SSH_ERR_KEY_NOT_FOUND) 1318 goto out; /* soft failure */ 1319 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1320 !fallback_sigtype) { 1321 if (sign_id->agent_fd != -1) 1322 loc = "agent "; 1323 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1324 loc = "token "; 1325 logit("%skey %s %s returned incorrect signature type", 1326 loc, sshkey_type(id->key), fp); 1327 continue; 1328 } 1329 error("%s: signing failed: %s", __func__, ssh_err(r)); 1330 goto out; 1331 } 1332 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1333 fatal("%s: no signature", __func__); 1334 1335 /* append signature */ 1336 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1337 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1338 1339 #ifdef DEBUG_PK 1340 sshbuf_dump(b, stderr); 1341 #endif 1342 /* skip session id and packet type */ 1343 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1344 fatal("%s: consume: %s", __func__, ssh_err(r)); 1345 1346 /* put remaining data from buffer into packet */ 1347 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1348 (r = sshpkt_putb(ssh, b)) != 0 || 1349 (r = sshpkt_send(ssh)) != 0) 1350 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1351 1352 /* success */ 1353 sent = 1; 1354 1355 out: 1356 free(fp); 1357 free(alg); 1358 sshbuf_free(b); 1359 freezero(signature, slen); 1360 return sent; 1361 } 1362 1363 static int 1364 send_pubkey_test(struct ssh *ssh, Identity *id) 1365 { 1366 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1367 u_char *blob = NULL; 1368 char *alg = NULL; 1369 size_t bloblen; 1370 u_int have_sig = 0; 1371 int sent = 0, r; 1372 1373 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1374 debug("%s: no mutual signature algorithm", __func__); 1375 goto out; 1376 } 1377 1378 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1379 /* we cannot handle this key */ 1380 debug3("%s: cannot handle key", __func__); 1381 goto out; 1382 } 1383 /* register callback for USERAUTH_PK_OK message */ 1384 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1385 1386 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1387 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1388 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1389 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1390 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1391 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1392 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1393 (r = sshpkt_send(ssh)) != 0) 1394 fatal("%s: %s", __func__, ssh_err(r)); 1395 sent = 1; 1396 1397 out: 1398 free(alg); 1399 free(blob); 1400 return sent; 1401 } 1402 1403 static struct sshkey * 1404 load_identity_file(Identity *id) 1405 { 1406 struct sshkey *private = NULL; 1407 char prompt[300], *passphrase, *comment; 1408 int r, perm_ok = 0, quit = 0, i; 1409 struct stat st; 1410 1411 if (stat(id->filename, &st) < 0) { 1412 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1413 id->filename, strerror(errno)); 1414 return NULL; 1415 } 1416 snprintf(prompt, sizeof prompt, 1417 "Enter passphrase for key '%.100s': ", id->filename); 1418 for (i = 0; i <= options.number_of_password_prompts; i++) { 1419 if (i == 0) 1420 passphrase = ""; 1421 else { 1422 passphrase = read_passphrase(prompt, 0); 1423 if (*passphrase == '\0') { 1424 debug2("no passphrase given, try next key"); 1425 free(passphrase); 1426 break; 1427 } 1428 } 1429 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1430 passphrase, &private, &comment, &perm_ok))) { 1431 case 0: 1432 break; 1433 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1434 if (options.batch_mode) { 1435 quit = 1; 1436 break; 1437 } 1438 if (i != 0) 1439 debug2("bad passphrase given, try again..."); 1440 break; 1441 case SSH_ERR_SYSTEM_ERROR: 1442 if (errno == ENOENT) { 1443 debug2("Load key \"%s\": %s", 1444 id->filename, ssh_err(r)); 1445 quit = 1; 1446 break; 1447 } 1448 /* FALLTHROUGH */ 1449 default: 1450 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1451 quit = 1; 1452 break; 1453 } 1454 if (!quit && private != NULL && id->agent_fd == -1 && 1455 !(id->key && id->isprivate)) 1456 maybe_add_key_to_agent(id->filename, private, comment, 1457 passphrase); 1458 if (i > 0) 1459 freezero(passphrase, strlen(passphrase)); 1460 free(comment); 1461 if (private != NULL || quit) 1462 break; 1463 } 1464 return private; 1465 } 1466 1467 static int 1468 key_type_allowed_by_config(struct sshkey *key) 1469 { 1470 if (match_pattern_list(sshkey_ssh_name(key), 1471 options.pubkey_key_types, 0) == 1) 1472 return 1; 1473 1474 /* RSA keys/certs might be allowed by alternate signature types */ 1475 switch (key->type) { 1476 case KEY_RSA: 1477 if (match_pattern_list("rsa-sha2-512", 1478 options.pubkey_key_types, 0) == 1) 1479 return 1; 1480 if (match_pattern_list("rsa-sha2-256", 1481 options.pubkey_key_types, 0) == 1) 1482 return 1; 1483 break; 1484 case KEY_RSA_CERT: 1485 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1486 options.pubkey_key_types, 0) == 1) 1487 return 1; 1488 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1489 options.pubkey_key_types, 0) == 1) 1490 return 1; 1491 break; 1492 } 1493 return 0; 1494 } 1495 1496 1497 /* 1498 * try keys in the following order: 1499 * 1. certificates listed in the config file 1500 * 2. other input certificates 1501 * 3. agent keys that are found in the config file 1502 * 4. other agent keys 1503 * 5. keys that are only listed in the config file 1504 */ 1505 static void 1506 pubkey_prepare(Authctxt *authctxt) 1507 { 1508 struct identity *id, *id2, *tmp; 1509 struct idlist agent, files, *preferred; 1510 struct sshkey *key; 1511 int agent_fd = -1, i, r, found; 1512 size_t j; 1513 struct ssh_identitylist *idlist; 1514 char *ident; 1515 1516 TAILQ_INIT(&agent); /* keys from the agent */ 1517 TAILQ_INIT(&files); /* keys from the config file */ 1518 preferred = &authctxt->keys; 1519 TAILQ_INIT(preferred); /* preferred order of keys */ 1520 1521 /* list of keys stored in the filesystem and PKCS#11 */ 1522 for (i = 0; i < options.num_identity_files; i++) { 1523 key = options.identity_keys[i]; 1524 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1525 continue; 1526 options.identity_keys[i] = NULL; 1527 id = xcalloc(1, sizeof(*id)); 1528 id->agent_fd = -1; 1529 id->key = key; 1530 id->filename = xstrdup(options.identity_files[i]); 1531 id->userprovided = options.identity_file_userprovided[i]; 1532 TAILQ_INSERT_TAIL(&files, id, next); 1533 } 1534 /* list of certificates specified by user */ 1535 for (i = 0; i < options.num_certificate_files; i++) { 1536 key = options.certificates[i]; 1537 if (!sshkey_is_cert(key) || key->cert == NULL || 1538 key->cert->type != SSH2_CERT_TYPE_USER) 1539 continue; 1540 id = xcalloc(1, sizeof(*id)); 1541 id->agent_fd = -1; 1542 id->key = key; 1543 id->filename = xstrdup(options.certificate_files[i]); 1544 id->userprovided = options.certificate_file_userprovided[i]; 1545 TAILQ_INSERT_TAIL(preferred, id, next); 1546 } 1547 /* list of keys supported by the agent */ 1548 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1549 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1550 debug("%s: ssh_get_authentication_socket: %s", 1551 __func__, ssh_err(r)); 1552 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1553 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1554 debug("%s: ssh_fetch_identitylist: %s", 1555 __func__, ssh_err(r)); 1556 close(agent_fd); 1557 } else { 1558 for (j = 0; j < idlist->nkeys; j++) { 1559 found = 0; 1560 TAILQ_FOREACH(id, &files, next) { 1561 /* 1562 * agent keys from the config file are 1563 * preferred 1564 */ 1565 if (sshkey_equal(idlist->keys[j], id->key)) { 1566 TAILQ_REMOVE(&files, id, next); 1567 TAILQ_INSERT_TAIL(preferred, id, next); 1568 id->agent_fd = agent_fd; 1569 found = 1; 1570 break; 1571 } 1572 } 1573 if (!found && !options.identities_only) { 1574 id = xcalloc(1, sizeof(*id)); 1575 /* XXX "steals" key/comment from idlist */ 1576 id->key = idlist->keys[j]; 1577 id->filename = idlist->comments[j]; 1578 idlist->keys[j] = NULL; 1579 idlist->comments[j] = NULL; 1580 id->agent_fd = agent_fd; 1581 TAILQ_INSERT_TAIL(&agent, id, next); 1582 } 1583 } 1584 ssh_free_identitylist(idlist); 1585 /* append remaining agent keys */ 1586 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1587 TAILQ_REMOVE(&agent, id, next); 1588 TAILQ_INSERT_TAIL(preferred, id, next); 1589 } 1590 authctxt->agent_fd = agent_fd; 1591 } 1592 /* Prefer PKCS11 keys that are explicitly listed */ 1593 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1594 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1595 continue; 1596 found = 0; 1597 TAILQ_FOREACH(id2, &files, next) { 1598 if (id2->key == NULL || 1599 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1600 continue; 1601 if (sshkey_equal(id->key, id2->key)) { 1602 TAILQ_REMOVE(&files, id, next); 1603 TAILQ_INSERT_TAIL(preferred, id, next); 1604 found = 1; 1605 break; 1606 } 1607 } 1608 /* If IdentitiesOnly set and key not found then don't use it */ 1609 if (!found && options.identities_only) { 1610 TAILQ_REMOVE(&files, id, next); 1611 freezero(id, sizeof(*id)); 1612 } 1613 } 1614 /* append remaining keys from the config file */ 1615 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1616 TAILQ_REMOVE(&files, id, next); 1617 TAILQ_INSERT_TAIL(preferred, id, next); 1618 } 1619 /* finally, filter by PubkeyAcceptedKeyTypes */ 1620 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1621 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1622 debug("Skipping %s key %s - " 1623 "not in PubkeyAcceptedKeyTypes", 1624 sshkey_ssh_name(id->key), id->filename); 1625 TAILQ_REMOVE(preferred, id, next); 1626 sshkey_free(id->key); 1627 free(id->filename); 1628 memset(id, 0, sizeof(*id)); 1629 continue; 1630 } 1631 } 1632 /* List the keys we plan on using */ 1633 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1634 ident = format_identity(id); 1635 debug("Will attempt key: %s", ident); 1636 free(ident); 1637 } 1638 debug2("%s: done", __func__); 1639 } 1640 1641 static void 1642 pubkey_cleanup(struct ssh *ssh) 1643 { 1644 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1645 Identity *id; 1646 1647 if (authctxt->agent_fd != -1) { 1648 ssh_close_authentication_socket(authctxt->agent_fd); 1649 authctxt->agent_fd = -1; 1650 } 1651 for (id = TAILQ_FIRST(&authctxt->keys); id; 1652 id = TAILQ_FIRST(&authctxt->keys)) { 1653 TAILQ_REMOVE(&authctxt->keys, id, next); 1654 sshkey_free(id->key); 1655 free(id->filename); 1656 free(id); 1657 } 1658 } 1659 1660 static void 1661 pubkey_reset(Authctxt *authctxt) 1662 { 1663 Identity *id; 1664 1665 TAILQ_FOREACH(id, &authctxt->keys, next) 1666 id->tried = 0; 1667 } 1668 1669 static int 1670 try_identity(Identity *id) 1671 { 1672 if (!id->key) 1673 return (0); 1674 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1675 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1676 debug("Skipped %s key %s for RSA/MD5 server", 1677 sshkey_type(id->key), id->filename); 1678 return (0); 1679 } 1680 return 1; 1681 } 1682 1683 static int 1684 userauth_pubkey(struct ssh *ssh) 1685 { 1686 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1687 Identity *id; 1688 int sent = 0; 1689 char *ident; 1690 1691 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1692 if (id->tried++) 1693 return (0); 1694 /* move key to the end of the queue */ 1695 TAILQ_REMOVE(&authctxt->keys, id, next); 1696 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1697 /* 1698 * send a test message if we have the public key. for 1699 * encrypted keys we cannot do this and have to load the 1700 * private key instead 1701 */ 1702 if (id->key != NULL) { 1703 if (try_identity(id)) { 1704 ident = format_identity(id); 1705 debug("Offering public key: %s", ident); 1706 free(ident); 1707 sent = send_pubkey_test(ssh, id); 1708 } 1709 } else { 1710 debug("Trying private key: %s", id->filename); 1711 id->key = load_identity_file(id); 1712 if (id->key != NULL) { 1713 if (try_identity(id)) { 1714 id->isprivate = 1; 1715 sent = sign_and_send_pubkey(ssh, id); 1716 } 1717 sshkey_free(id->key); 1718 id->key = NULL; 1719 id->isprivate = 0; 1720 } 1721 } 1722 if (sent) 1723 return (sent); 1724 } 1725 return (0); 1726 } 1727 1728 /* 1729 * Send userauth request message specifying keyboard-interactive method. 1730 */ 1731 static int 1732 userauth_kbdint(struct ssh *ssh) 1733 { 1734 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1735 int r; 1736 1737 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1738 return 0; 1739 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1740 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1741 debug3("userauth_kbdint: disable: no info_req_seen"); 1742 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1743 return 0; 1744 } 1745 1746 debug2("userauth_kbdint"); 1747 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1748 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1749 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1750 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1751 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1752 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1753 options.kbd_interactive_devices : "")) != 0 || 1754 (r = sshpkt_send(ssh)) != 0) 1755 fatal("%s: %s", __func__, ssh_err(r)); 1756 1757 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1758 return 1; 1759 } 1760 1761 /* 1762 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1763 */ 1764 static int 1765 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1766 { 1767 Authctxt *authctxt = ssh->authctxt; 1768 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1769 char *response = NULL; 1770 u_char echo = 0; 1771 u_int num_prompts, i; 1772 int r; 1773 1774 debug2("input_userauth_info_req"); 1775 1776 if (authctxt == NULL) 1777 fatal("input_userauth_info_req: no authentication context"); 1778 1779 authctxt->info_req_seen = 1; 1780 1781 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1782 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1783 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1784 goto out; 1785 if (strlen(name) > 0) 1786 logit("%s", name); 1787 if (strlen(inst) > 0) 1788 logit("%s", inst); 1789 1790 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1791 goto out; 1792 /* 1793 * Begin to build info response packet based on prompts requested. 1794 * We commit to providing the correct number of responses, so if 1795 * further on we run into a problem that prevents this, we have to 1796 * be sure and clean this up and send a correct error response. 1797 */ 1798 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1799 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1800 goto out; 1801 1802 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1803 for (i = 0; i < num_prompts; i++) { 1804 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1805 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1806 goto out; 1807 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1808 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1809 goto out; 1810 freezero(response, strlen(response)); 1811 free(prompt); 1812 response = prompt = NULL; 1813 } 1814 /* done with parsing incoming message. */ 1815 if ((r = sshpkt_get_end(ssh)) != 0 || 1816 (r = sshpkt_add_padding(ssh, 64)) != 0) 1817 goto out; 1818 r = sshpkt_send(ssh); 1819 out: 1820 if (response) 1821 freezero(response, strlen(response)); 1822 free(prompt); 1823 free(name); 1824 free(inst); 1825 free(lang); 1826 return r; 1827 } 1828 1829 static int 1830 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1831 const u_char *data, size_t datalen) 1832 { 1833 struct sshbuf *b; 1834 struct stat st; 1835 pid_t pid; 1836 int i, r, to[2], from[2], status; 1837 int sock = ssh_packet_get_connection_in(ssh); 1838 u_char rversion = 0, version = 2; 1839 void (*osigchld)(int); 1840 1841 *sigp = NULL; 1842 *lenp = 0; 1843 1844 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1845 error("%s: not installed: %s", __func__, strerror(errno)); 1846 return -1; 1847 } 1848 if (fflush(stdout) != 0) { 1849 error("%s: fflush: %s", __func__, strerror(errno)); 1850 return -1; 1851 } 1852 if (pipe(to) < 0) { 1853 error("%s: pipe: %s", __func__, strerror(errno)); 1854 return -1; 1855 } 1856 if (pipe(from) < 0) { 1857 error("%s: pipe: %s", __func__, strerror(errno)); 1858 return -1; 1859 } 1860 if ((pid = fork()) < 0) { 1861 error("%s: fork: %s", __func__, strerror(errno)); 1862 return -1; 1863 } 1864 osigchld = signal(SIGCHLD, SIG_DFL); 1865 if (pid == 0) { 1866 /* keep the socket on exec */ 1867 fcntl(sock, F_SETFD, 0); 1868 close(from[0]); 1869 if (dup2(from[1], STDOUT_FILENO) < 0) 1870 fatal("%s: dup2: %s", __func__, strerror(errno)); 1871 close(to[1]); 1872 if (dup2(to[0], STDIN_FILENO) < 0) 1873 fatal("%s: dup2: %s", __func__, strerror(errno)); 1874 close(from[1]); 1875 close(to[0]); 1876 /* Close everything but stdio and the socket */ 1877 for (i = STDERR_FILENO + 1; i < sock; i++) 1878 close(i); 1879 closefrom(sock + 1); 1880 debug3("%s: [child] pid=%ld, exec %s", 1881 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1882 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1883 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1884 strerror(errno)); 1885 } 1886 close(from[1]); 1887 close(to[0]); 1888 1889 if ((b = sshbuf_new()) == NULL) 1890 fatal("%s: sshbuf_new failed", __func__); 1891 /* send # of sock, data to be signed */ 1892 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1893 (r = sshbuf_put_string(b, data, datalen)) != 0) 1894 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1895 if (ssh_msg_send(to[1], version, b) == -1) 1896 fatal("%s: couldn't send request", __func__); 1897 sshbuf_reset(b); 1898 r = ssh_msg_recv(from[0], b); 1899 close(from[0]); 1900 close(to[1]); 1901 if (r < 0) { 1902 error("%s: no reply", __func__); 1903 goto fail; 1904 } 1905 1906 errno = 0; 1907 while (waitpid(pid, &status, 0) < 0) { 1908 if (errno != EINTR) { 1909 error("%s: waitpid %ld: %s", 1910 __func__, (long)pid, strerror(errno)); 1911 goto fail; 1912 } 1913 } 1914 if (!WIFEXITED(status)) { 1915 error("%s: exited abnormally", __func__); 1916 goto fail; 1917 } 1918 if (WEXITSTATUS(status) != 0) { 1919 error("%s: exited with status %d", 1920 __func__, WEXITSTATUS(status)); 1921 goto fail; 1922 } 1923 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1924 error("%s: buffer error: %s", __func__, ssh_err(r)); 1925 goto fail; 1926 } 1927 if (rversion != version) { 1928 error("%s: bad version", __func__); 1929 goto fail; 1930 } 1931 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1932 error("%s: buffer error: %s", __func__, ssh_err(r)); 1933 fail: 1934 signal(SIGCHLD, osigchld); 1935 sshbuf_free(b); 1936 return -1; 1937 } 1938 signal(SIGCHLD, osigchld); 1939 sshbuf_free(b); 1940 1941 return 0; 1942 } 1943 1944 static int 1945 userauth_hostbased(struct ssh *ssh) 1946 { 1947 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1948 struct sshkey *private = NULL; 1949 struct sshbuf *b = NULL; 1950 u_char *sig = NULL, *keyblob = NULL; 1951 char *fp = NULL, *chost = NULL, *lname = NULL; 1952 size_t siglen = 0, keylen = 0; 1953 int i, r, success = 0; 1954 1955 if (authctxt->ktypes == NULL) { 1956 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1957 authctxt->ktypes = authctxt->oktypes; 1958 } 1959 1960 /* 1961 * Work through each listed type pattern in HostbasedKeyTypes, 1962 * trying each hostkey that matches the type in turn. 1963 */ 1964 for (;;) { 1965 if (authctxt->active_ktype == NULL) 1966 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1967 if (authctxt->active_ktype == NULL || 1968 *authctxt->active_ktype == '\0') 1969 break; 1970 debug3("%s: trying key type %s", __func__, 1971 authctxt->active_ktype); 1972 1973 /* check for a useful key */ 1974 private = NULL; 1975 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1976 if (authctxt->sensitive->keys[i] == NULL || 1977 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1978 continue; 1979 if (match_pattern_list( 1980 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1981 authctxt->active_ktype, 0) != 1) 1982 continue; 1983 /* we take and free the key */ 1984 private = authctxt->sensitive->keys[i]; 1985 authctxt->sensitive->keys[i] = NULL; 1986 break; 1987 } 1988 /* Found one */ 1989 if (private != NULL) 1990 break; 1991 /* No more keys of this type; advance */ 1992 authctxt->active_ktype = NULL; 1993 } 1994 if (private == NULL) { 1995 free(authctxt->oktypes); 1996 authctxt->oktypes = authctxt->ktypes = NULL; 1997 authctxt->active_ktype = NULL; 1998 debug("No more client hostkeys for hostbased authentication."); 1999 goto out; 2000 } 2001 2002 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 2003 SSH_FP_DEFAULT)) == NULL) { 2004 error("%s: sshkey_fingerprint failed", __func__); 2005 goto out; 2006 } 2007 debug("%s: trying hostkey %s %s", 2008 __func__, sshkey_ssh_name(private), fp); 2009 2010 /* figure out a name for the client host */ 2011 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2012 if (lname == NULL) { 2013 error("%s: cannot get local ipaddr/name", __func__); 2014 goto out; 2015 } 2016 2017 /* XXX sshbuf_put_stringf? */ 2018 xasprintf(&chost, "%s.", lname); 2019 debug2("%s: chost %s", __func__, chost); 2020 2021 /* construct data */ 2022 if ((b = sshbuf_new()) == NULL) { 2023 error("%s: sshbuf_new failed", __func__); 2024 goto out; 2025 } 2026 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2027 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2028 goto out; 2029 } 2030 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2031 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2032 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2033 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2034 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2035 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2036 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2037 (r = sshbuf_put_cstring(b, chost)) != 0 || 2038 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2039 error("%s: buffer error: %s", __func__, ssh_err(r)); 2040 goto out; 2041 } 2042 2043 #ifdef DEBUG_PK 2044 sshbuf_dump(b, stderr); 2045 #endif 2046 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2047 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2048 error("sign using hostkey %s %s failed", 2049 sshkey_ssh_name(private), fp); 2050 goto out; 2051 } 2052 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2053 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2054 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2055 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2056 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2057 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2058 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2059 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2060 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2061 (r = sshpkt_send(ssh)) != 0) { 2062 error("%s: packet error: %s", __func__, ssh_err(r)); 2063 goto out; 2064 } 2065 success = 1; 2066 2067 out: 2068 if (sig != NULL) 2069 freezero(sig, siglen); 2070 free(keyblob); 2071 free(lname); 2072 free(fp); 2073 free(chost); 2074 sshkey_free(private); 2075 sshbuf_free(b); 2076 2077 return success; 2078 } 2079 2080 /* find auth method */ 2081 2082 /* 2083 * given auth method name, if configurable options permit this method fill 2084 * in auth_ident field and return true, otherwise return false. 2085 */ 2086 static int 2087 authmethod_is_enabled(Authmethod *method) 2088 { 2089 if (method == NULL) 2090 return 0; 2091 /* return false if options indicate this method is disabled */ 2092 if (method->enabled == NULL || *method->enabled == 0) 2093 return 0; 2094 /* return false if batch mode is enabled but method needs interactive mode */ 2095 if (method->batch_flag != NULL && *method->batch_flag != 0) 2096 return 0; 2097 return 1; 2098 } 2099 2100 static Authmethod * 2101 authmethod_lookup(const char *name) 2102 { 2103 Authmethod *method = NULL; 2104 if (name != NULL) 2105 for (method = authmethods; method->name != NULL; method++) 2106 if (strcmp(name, method->name) == 0) 2107 return method; 2108 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2109 return NULL; 2110 } 2111 2112 /* XXX internal state */ 2113 static Authmethod *current = NULL; 2114 static char *supported = NULL; 2115 static char *preferred = NULL; 2116 2117 /* 2118 * Given the authentication method list sent by the server, return the 2119 * next method we should try. If the server initially sends a nil list, 2120 * use a built-in default list. 2121 */ 2122 static Authmethod * 2123 authmethod_get(char *authlist) 2124 { 2125 char *name = NULL; 2126 u_int next; 2127 2128 /* Use a suitable default if we're passed a nil list. */ 2129 if (authlist == NULL || strlen(authlist) == 0) 2130 authlist = options.preferred_authentications; 2131 2132 if (supported == NULL || strcmp(authlist, supported) != 0) { 2133 debug3("start over, passed a different list %s", authlist); 2134 free(supported); 2135 supported = xstrdup(authlist); 2136 preferred = options.preferred_authentications; 2137 debug3("preferred %s", preferred); 2138 current = NULL; 2139 } else if (current != NULL && authmethod_is_enabled(current)) 2140 return current; 2141 2142 for (;;) { 2143 if ((name = match_list(preferred, supported, &next)) == NULL) { 2144 debug("No more authentication methods to try."); 2145 current = NULL; 2146 return NULL; 2147 } 2148 preferred += next; 2149 debug3("authmethod_lookup %s", name); 2150 debug3("remaining preferred: %s", preferred); 2151 if ((current = authmethod_lookup(name)) != NULL && 2152 authmethod_is_enabled(current)) { 2153 debug3("authmethod_is_enabled %s", name); 2154 debug("Next authentication method: %s", name); 2155 free(name); 2156 return current; 2157 } 2158 free(name); 2159 } 2160 } 2161 2162 static char * 2163 authmethods_get(void) 2164 { 2165 Authmethod *method = NULL; 2166 struct sshbuf *b; 2167 char *list; 2168 int r; 2169 2170 if ((b = sshbuf_new()) == NULL) 2171 fatal("%s: sshbuf_new failed", __func__); 2172 for (method = authmethods; method->name != NULL; method++) { 2173 if (authmethod_is_enabled(method)) { 2174 if ((r = sshbuf_putf(b, "%s%s", 2175 sshbuf_len(b) ? "," : "", method->name)) != 0) 2176 fatal("%s: buffer error: %s", 2177 __func__, ssh_err(r)); 2178 } 2179 } 2180 if ((list = sshbuf_dup_string(b)) == NULL) 2181 fatal("%s: sshbuf_dup_string failed", __func__); 2182 sshbuf_free(b); 2183 return list; 2184 } 2185