1 /* $OpenBSD: sshconnect2.c,v 1.305 2019/05/31 03:20:07 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * Copyright (c) 2008 Damien Miller. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/socket.h> 29 #include <sys/wait.h> 30 #include <sys/queue.h> 31 #include <sys/stat.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <string.h> 38 #include <signal.h> 39 #include <pwd.h> 40 #include <unistd.h> 41 #include <vis.h> 42 43 #include "xmalloc.h" 44 #include "ssh.h" 45 #include "ssh2.h" 46 #include "sshbuf.h" 47 #include "packet.h" 48 #include "compat.h" 49 #include "cipher.h" 50 #include "sshkey.h" 51 #include "kex.h" 52 #include "myproposal.h" 53 #include "sshconnect.h" 54 #include "authfile.h" 55 #include "dh.h" 56 #include "authfd.h" 57 #include "log.h" 58 #include "misc.h" 59 #include "readconf.h" 60 #include "match.h" 61 #include "dispatch.h" 62 #include "canohost.h" 63 #include "msg.h" 64 #include "pathnames.h" 65 #include "uidswap.h" 66 #include "hostfile.h" 67 #include "ssherr.h" 68 #include "utf8.h" 69 70 #ifdef GSSAPI 71 #include "ssh-gss.h" 72 #endif 73 74 /* import */ 75 extern char *client_version_string; 76 extern char *server_version_string; 77 extern Options options; 78 79 /* 80 * SSH2 key exchange 81 */ 82 83 u_char *session_id2 = NULL; 84 u_int session_id2_len = 0; 85 86 char *xxx_host; 87 struct sockaddr *xxx_hostaddr; 88 89 static int 90 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) 91 { 92 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) 93 fatal("Host key verification failed."); 94 return 0; 95 } 96 97 static char * 98 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port) 99 { 100 char *oavail, *avail, *first, *last, *alg, *hostname, *ret; 101 size_t maxlen; 102 struct hostkeys *hostkeys; 103 int ktype; 104 u_int i; 105 106 /* Find all hostkeys for this hostname */ 107 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL); 108 hostkeys = init_hostkeys(); 109 for (i = 0; i < options.num_user_hostfiles; i++) 110 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]); 111 for (i = 0; i < options.num_system_hostfiles; i++) 112 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]); 113 114 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG); 115 maxlen = strlen(avail) + 1; 116 first = xmalloc(maxlen); 117 last = xmalloc(maxlen); 118 *first = *last = '\0'; 119 120 #define ALG_APPEND(to, from) \ 121 do { \ 122 if (*to != '\0') \ 123 strlcat(to, ",", maxlen); \ 124 strlcat(to, from, maxlen); \ 125 } while (0) 126 127 while ((alg = strsep(&avail, ",")) && *alg != '\0') { 128 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) 129 fatal("%s: unknown alg %s", __func__, alg); 130 if (lookup_key_in_hostkeys_by_type(hostkeys, 131 sshkey_type_plain(ktype), NULL)) 132 ALG_APPEND(first, alg); 133 else 134 ALG_APPEND(last, alg); 135 } 136 #undef ALG_APPEND 137 xasprintf(&ret, "%s%s%s", first, 138 (*first == '\0' || *last == '\0') ? "" : ",", last); 139 if (*first != '\0') 140 debug3("%s: prefer hostkeyalgs: %s", __func__, first); 141 142 free(first); 143 free(last); 144 free(hostname); 145 free(oavail); 146 free_hostkeys(hostkeys); 147 148 return ret; 149 } 150 151 void 152 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) 153 { 154 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 155 char *s, *all_key; 156 int r; 157 158 xxx_host = host; 159 xxx_hostaddr = hostaddr; 160 161 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) 162 fatal("%s: kex_names_cat", __func__); 163 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s); 164 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 165 compat_cipher_proposal(options.ciphers); 166 myproposal[PROPOSAL_ENC_ALGS_STOC] = 167 compat_cipher_proposal(options.ciphers); 168 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 169 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ? 170 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib"; 171 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 172 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 173 if (options.hostkeyalgorithms != NULL) { 174 all_key = sshkey_alg_list(0, 0, 1, ','); 175 if (kex_assemble_names(&options.hostkeyalgorithms, 176 KEX_DEFAULT_PK_ALG, all_key) != 0) 177 fatal("%s: kex_assemble_namelist", __func__); 178 free(all_key); 179 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 180 compat_pkalg_proposal(options.hostkeyalgorithms); 181 } else { 182 /* Enforce default */ 183 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG); 184 /* Prefer algorithms that we already have keys for */ 185 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 186 compat_pkalg_proposal( 187 order_hostkeyalgs(host, hostaddr, port)); 188 } 189 190 if (options.rekey_limit || options.rekey_interval) 191 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 192 options.rekey_interval); 193 194 /* start key exchange */ 195 if ((r = kex_setup(ssh, myproposal)) != 0) 196 fatal("kex_setup: %s", ssh_err(r)); 197 #ifdef WITH_OPENSSL 198 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; 199 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; 200 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; 201 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; 202 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; 203 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 204 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 205 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; 206 #endif 207 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; 208 ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client; 209 ssh->kex->verify_host_key=&verify_host_key_callback; 210 211 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); 212 213 /* remove ext-info from the KEX proposals for rekeying */ 214 myproposal[PROPOSAL_KEX_ALGS] = 215 compat_kex_proposal(options.kex_algorithms); 216 if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) 217 fatal("kex_prop2buf: %s", ssh_err(r)); 218 219 session_id2 = ssh->kex->session_id; 220 session_id2_len = ssh->kex->session_id_len; 221 222 #ifdef DEBUG_KEXDH 223 /* send 1st encrypted/maced/compressed message */ 224 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 225 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 226 (r = sshpkt_send(ssh)) != 0 || 227 (r = ssh_packet_write_wait(ssh)) != 0) 228 fatal("%s: %s", __func__, ssh_err(r)); 229 #endif 230 } 231 232 /* 233 * Authenticate user 234 */ 235 236 typedef struct cauthctxt Authctxt; 237 typedef struct cauthmethod Authmethod; 238 typedef struct identity Identity; 239 typedef struct idlist Idlist; 240 241 struct identity { 242 TAILQ_ENTRY(identity) next; 243 int agent_fd; /* >=0 if agent supports key */ 244 struct sshkey *key; /* public/private key */ 245 char *filename; /* comment for agent-only keys */ 246 int tried; 247 int isprivate; /* key points to the private key */ 248 int userprovided; 249 }; 250 TAILQ_HEAD(idlist, identity); 251 252 struct cauthctxt { 253 const char *server_user; 254 const char *local_user; 255 const char *host; 256 const char *service; 257 struct cauthmethod *method; 258 sig_atomic_t success; 259 char *authlist; 260 #ifdef GSSAPI 261 /* gssapi */ 262 gss_OID_set gss_supported_mechs; 263 u_int mech_tried; 264 #endif 265 /* pubkey */ 266 struct idlist keys; 267 int agent_fd; 268 /* hostbased */ 269 Sensitive *sensitive; 270 char *oktypes, *ktypes; 271 const char *active_ktype; 272 /* kbd-interactive */ 273 int info_req_seen; 274 int attempt_kbdint; 275 /* password */ 276 int attempt_passwd; 277 /* generic */ 278 void *methoddata; 279 }; 280 281 struct cauthmethod { 282 char *name; /* string to compare against server's list */ 283 int (*userauth)(struct ssh *ssh); 284 void (*cleanup)(struct ssh *ssh); 285 int *enabled; /* flag in option struct that enables method */ 286 int *batch_flag; /* flag in option struct that disables method */ 287 }; 288 289 static int input_userauth_service_accept(int, u_int32_t, struct ssh *); 290 static int input_userauth_ext_info(int, u_int32_t, struct ssh *); 291 static int input_userauth_success(int, u_int32_t, struct ssh *); 292 static int input_userauth_failure(int, u_int32_t, struct ssh *); 293 static int input_userauth_banner(int, u_int32_t, struct ssh *); 294 static int input_userauth_error(int, u_int32_t, struct ssh *); 295 static int input_userauth_info_req(int, u_int32_t, struct ssh *); 296 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); 297 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); 298 299 static int userauth_none(struct ssh *); 300 static int userauth_pubkey(struct ssh *); 301 static int userauth_passwd(struct ssh *); 302 static int userauth_kbdint(struct ssh *); 303 static int userauth_hostbased(struct ssh *); 304 305 #ifdef GSSAPI 306 static int userauth_gssapi(struct ssh *); 307 static void userauth_gssapi_cleanup(struct ssh *); 308 static int input_gssapi_response(int type, u_int32_t, struct ssh *); 309 static int input_gssapi_token(int type, u_int32_t, struct ssh *); 310 static int input_gssapi_error(int, u_int32_t, struct ssh *); 311 static int input_gssapi_errtok(int, u_int32_t, struct ssh *); 312 #endif 313 314 void userauth(struct ssh *, char *); 315 316 static void pubkey_cleanup(struct ssh *); 317 static int sign_and_send_pubkey(struct ssh *ssh, Identity *); 318 static void pubkey_prepare(Authctxt *); 319 static void pubkey_reset(Authctxt *); 320 static struct sshkey *load_identity_file(Identity *); 321 322 static Authmethod *authmethod_get(char *authlist); 323 static Authmethod *authmethod_lookup(const char *name); 324 static char *authmethods_get(void); 325 326 Authmethod authmethods[] = { 327 #ifdef GSSAPI 328 {"gssapi-with-mic", 329 userauth_gssapi, 330 userauth_gssapi_cleanup, 331 &options.gss_authentication, 332 NULL}, 333 #endif 334 {"hostbased", 335 userauth_hostbased, 336 NULL, 337 &options.hostbased_authentication, 338 NULL}, 339 {"publickey", 340 userauth_pubkey, 341 NULL, 342 &options.pubkey_authentication, 343 NULL}, 344 {"keyboard-interactive", 345 userauth_kbdint, 346 NULL, 347 &options.kbd_interactive_authentication, 348 &options.batch_mode}, 349 {"password", 350 userauth_passwd, 351 NULL, 352 &options.password_authentication, 353 &options.batch_mode}, 354 {"none", 355 userauth_none, 356 NULL, 357 NULL, 358 NULL}, 359 {NULL, NULL, NULL, NULL, NULL} 360 }; 361 362 void 363 ssh_userauth2(struct ssh *ssh, const char *local_user, 364 const char *server_user, char *host, Sensitive *sensitive) 365 { 366 Authctxt authctxt; 367 int r; 368 369 if (options.challenge_response_authentication) 370 options.kbd_interactive_authentication = 1; 371 if (options.preferred_authentications == NULL) 372 options.preferred_authentications = authmethods_get(); 373 374 /* setup authentication context */ 375 memset(&authctxt, 0, sizeof(authctxt)); 376 authctxt.server_user = server_user; 377 authctxt.local_user = local_user; 378 authctxt.host = host; 379 authctxt.service = "ssh-connection"; /* service name */ 380 authctxt.success = 0; 381 authctxt.method = authmethod_lookup("none"); 382 authctxt.authlist = NULL; 383 authctxt.methoddata = NULL; 384 authctxt.sensitive = sensitive; 385 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; 386 authctxt.info_req_seen = 0; 387 authctxt.attempt_kbdint = 0; 388 authctxt.attempt_passwd = 0; 389 #if GSSAPI 390 authctxt.gss_supported_mechs = NULL; 391 authctxt.mech_tried = 0; 392 #endif 393 authctxt.agent_fd = -1; 394 pubkey_prepare(&authctxt); 395 if (authctxt.method == NULL) { 396 fatal("%s: internal error: cannot send userauth none request", 397 __func__); 398 } 399 400 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 || 401 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 || 402 (r = sshpkt_send(ssh)) != 0) 403 fatal("%s: %s", __func__, ssh_err(r)); 404 405 ssh->authctxt = &authctxt; 406 ssh_dispatch_init(ssh, &input_userauth_error); 407 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info); 408 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept); 409 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */ 410 pubkey_cleanup(ssh); 411 ssh->authctxt = NULL; 412 413 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); 414 415 if (!authctxt.success) 416 fatal("Authentication failed."); 417 debug("Authentication succeeded (%s).", authctxt.method->name); 418 } 419 420 /* ARGSUSED */ 421 static int 422 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh) 423 { 424 int r; 425 426 if (ssh_packet_remaining(ssh) > 0) { 427 char *reply; 428 429 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0) 430 goto out; 431 debug2("service_accept: %s", reply); 432 free(reply); 433 } else { 434 debug2("buggy server: service_accept w/o service"); 435 } 436 if ((r = sshpkt_get_end(ssh)) != 0) 437 goto out; 438 debug("SSH2_MSG_SERVICE_ACCEPT received"); 439 440 /* initial userauth request */ 441 userauth_none(ssh); 442 443 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error); 444 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); 445 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); 446 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); 447 r = 0; 448 out: 449 return r; 450 } 451 452 /* ARGSUSED */ 453 static int 454 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh) 455 { 456 return kex_input_ext_info(type, seqnr, ssh); 457 } 458 459 void 460 userauth(struct ssh *ssh, char *authlist) 461 { 462 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 463 464 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 465 authctxt->method->cleanup(ssh); 466 467 free(authctxt->methoddata); 468 authctxt->methoddata = NULL; 469 if (authlist == NULL) { 470 authlist = authctxt->authlist; 471 } else { 472 free(authctxt->authlist); 473 authctxt->authlist = authlist; 474 } 475 for (;;) { 476 Authmethod *method = authmethod_get(authlist); 477 if (method == NULL) 478 fatal("%s@%s: Permission denied (%s).", 479 authctxt->server_user, authctxt->host, authlist); 480 authctxt->method = method; 481 482 /* reset the per method handler */ 483 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN, 484 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); 485 486 /* and try new method */ 487 if (method->userauth(ssh) != 0) { 488 debug2("we sent a %s packet, wait for reply", method->name); 489 break; 490 } else { 491 debug2("we did not send a packet, disable method"); 492 method->enabled = NULL; 493 } 494 } 495 } 496 497 /* ARGSUSED */ 498 static int 499 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh) 500 { 501 fatal("%s: bad message during authentication: type %d", __func__, type); 502 return 0; 503 } 504 505 /* ARGSUSED */ 506 static int 507 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh) 508 { 509 char *msg = NULL; 510 size_t len; 511 int r; 512 513 debug3("%s", __func__); 514 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 || 515 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) 516 goto out; 517 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) 518 fmprintf(stderr, "%s", msg); 519 r = 0; 520 out: 521 free(msg); 522 return r; 523 } 524 525 /* ARGSUSED */ 526 static int 527 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh) 528 { 529 Authctxt *authctxt = ssh->authctxt; 530 531 if (authctxt == NULL) 532 fatal("%s: no authentication context", __func__); 533 free(authctxt->authlist); 534 authctxt->authlist = NULL; 535 if (authctxt->method != NULL && authctxt->method->cleanup != NULL) 536 authctxt->method->cleanup(ssh); 537 free(authctxt->methoddata); 538 authctxt->methoddata = NULL; 539 authctxt->success = 1; /* break out */ 540 return 0; 541 } 542 543 #if 0 544 static int 545 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh) 546 { 547 Authctxt *authctxt = ssh->authctxt; 548 549 if (authctxt == NULL) 550 fatal("%s: no authentication context", __func__); 551 552 fatal("Unexpected authentication success during %s.", 553 authctxt->method->name); 554 return 0; 555 } 556 #endif 557 558 /* ARGSUSED */ 559 static int 560 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh) 561 { 562 Authctxt *authctxt = ssh->authctxt; 563 char *authlist = NULL; 564 u_char partial; 565 int r; 566 567 if (authctxt == NULL) 568 fatal("input_userauth_failure: no authentication context"); 569 570 if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 || 571 (r = sshpkt_get_u8(ssh, &partial)) != 0 || 572 (r = sshpkt_get_end(ssh)) != 0) 573 goto out; 574 575 if (partial != 0) { 576 verbose("Authenticated with partial success."); 577 /* reset state */ 578 pubkey_reset(authctxt); 579 } 580 debug("Authentications that can continue: %s", authlist); 581 582 userauth(ssh, authlist); 583 authlist = NULL; 584 out: 585 free(authlist); 586 return 0; 587 } 588 589 /* 590 * Format an identity for logging including filename, key type, fingerprint 591 * and location (agent, etc.). Caller must free. 592 */ 593 static char * 594 format_identity(Identity *id) 595 { 596 char *fp = NULL, *ret = NULL; 597 598 if (id->key != NULL) { 599 fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 600 SSH_FP_DEFAULT); 601 } 602 xasprintf(&ret, "%s %s%s%s%s%s%s", 603 id->filename, 604 id->key ? sshkey_type(id->key) : "", id->key ? " " : "", 605 fp ? fp : "", 606 id->userprovided ? " explicit" : "", 607 (id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "", 608 id->agent_fd != -1 ? " agent" : ""); 609 free(fp); 610 return ret; 611 } 612 613 /* ARGSUSED */ 614 static int 615 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh) 616 { 617 Authctxt *authctxt = ssh->authctxt; 618 struct sshkey *key = NULL; 619 Identity *id = NULL; 620 int pktype, found = 0, sent = 0; 621 size_t blen; 622 char *pkalg = NULL, *fp = NULL, *ident = NULL; 623 u_char *pkblob = NULL; 624 int r; 625 626 if (authctxt == NULL) 627 fatal("input_userauth_pk_ok: no authentication context"); 628 629 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || 630 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 || 631 (r = sshpkt_get_end(ssh)) != 0) 632 goto done; 633 634 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) { 635 debug("%s: server sent unknown pkalg %s", __func__, pkalg); 636 goto done; 637 } 638 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { 639 debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r)); 640 goto done; 641 } 642 if (key->type != pktype) { 643 error("input_userauth_pk_ok: type mismatch " 644 "for decoded key (received %d, expected %d)", 645 key->type, pktype); 646 goto done; 647 } 648 649 /* 650 * search keys in the reverse order, because last candidate has been 651 * moved to the end of the queue. this also avoids confusion by 652 * duplicate keys 653 */ 654 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { 655 if (sshkey_equal(key, id->key)) { 656 found = 1; 657 break; 658 } 659 } 660 if (!found || id == NULL) { 661 fp = sshkey_fingerprint(key, options.fingerprint_hash, 662 SSH_FP_DEFAULT); 663 error("%s: server replied with unknown key: %s %s", __func__, 664 sshkey_type(key), fp == NULL ? "<ERROR>" : fp); 665 goto done; 666 } 667 ident = format_identity(id); 668 debug("Server accepts key: %s", ident); 669 sent = sign_and_send_pubkey(ssh, id); 670 r = 0; 671 done: 672 sshkey_free(key); 673 free(ident); 674 free(fp); 675 free(pkalg); 676 free(pkblob); 677 678 /* try another method if we did not send a packet */ 679 if (r == 0 && sent == 0) 680 userauth(ssh, NULL); 681 return r; 682 } 683 684 #ifdef GSSAPI 685 static int 686 userauth_gssapi(struct ssh *ssh) 687 { 688 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 689 Gssctxt *gssctxt = NULL; 690 OM_uint32 min; 691 int r, ok = 0; 692 gss_OID mech = NULL; 693 694 /* Try one GSSAPI method at a time, rather than sending them all at 695 * once. */ 696 697 if (authctxt->gss_supported_mechs == NULL) 698 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); 699 700 /* Check to see whether the mechanism is usable before we offer it */ 701 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && 702 !ok) { 703 mech = &authctxt->gss_supported_mechs-> 704 elements[authctxt->mech_tried]; 705 /* My DER encoding requires length<128 */ 706 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, 707 mech, authctxt->host)) { 708 ok = 1; /* Mechanism works */ 709 } else { 710 authctxt->mech_tried++; 711 } 712 } 713 714 if (!ok || mech == NULL) 715 return 0; 716 717 authctxt->methoddata=(void *)gssctxt; 718 719 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 720 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 721 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 722 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 723 (r = sshpkt_put_u32(ssh, 1)) != 0 || 724 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 || 725 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 || 726 (r = sshpkt_put_u8(ssh, mech->length)) != 0 || 727 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 || 728 (r = sshpkt_send(ssh)) != 0) 729 fatal("%s: %s", __func__, ssh_err(r)); 730 731 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); 732 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 733 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); 734 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 735 736 authctxt->mech_tried++; /* Move along to next candidate */ 737 738 return 1; 739 } 740 741 static void 742 userauth_gssapi_cleanup(struct ssh *ssh) 743 { 744 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 745 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata; 746 747 ssh_gssapi_delete_ctx(&gssctxt); 748 authctxt->methoddata = NULL; 749 750 free(authctxt->gss_supported_mechs); 751 authctxt->gss_supported_mechs = NULL; 752 } 753 754 static OM_uint32 755 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok) 756 { 757 Authctxt *authctxt = ssh->authctxt; 758 Gssctxt *gssctxt = authctxt->methoddata; 759 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 760 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; 761 gss_buffer_desc gssbuf; 762 OM_uint32 status, ms, flags; 763 int r; 764 765 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 766 recv_tok, &send_tok, &flags); 767 768 if (send_tok.length > 0) { 769 u_char type = GSS_ERROR(status) ? 770 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK : 771 SSH2_MSG_USERAUTH_GSSAPI_TOKEN; 772 773 if ((r = sshpkt_start(ssh, type)) != 0 || 774 (r = sshpkt_put_string(ssh, send_tok.value, 775 send_tok.length)) != 0 || 776 (r = sshpkt_send(ssh)) != 0) 777 fatal("%s: %s", __func__, ssh_err(r)); 778 779 gss_release_buffer(&ms, &send_tok); 780 } 781 782 if (status == GSS_S_COMPLETE) { 783 /* send either complete or MIC, depending on mechanism */ 784 if (!(flags & GSS_C_INTEG_FLAG)) { 785 if ((r = sshpkt_start(ssh, 786 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 || 787 (r = sshpkt_send(ssh)) != 0) 788 fatal("%s: %s", __func__, ssh_err(r)); 789 } else { 790 struct sshbuf *b; 791 792 if ((b = sshbuf_new()) == NULL) 793 fatal("%s: sshbuf_new failed", __func__); 794 ssh_gssapi_buildmic(b, authctxt->server_user, 795 authctxt->service, "gssapi-with-mic"); 796 797 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) 798 fatal("%s: sshbuf_mutable_ptr failed", __func__); 799 gssbuf.length = sshbuf_len(b); 800 801 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); 802 803 if (!GSS_ERROR(status)) { 804 if ((r = sshpkt_start(ssh, 805 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 || 806 (r = sshpkt_put_string(ssh, mic.value, 807 mic.length)) != 0 || 808 (r = sshpkt_send(ssh)) != 0) 809 fatal("%s: %s", __func__, ssh_err(r)); 810 } 811 812 sshbuf_free(b); 813 gss_release_buffer(&ms, &mic); 814 } 815 } 816 817 return status; 818 } 819 820 /* ARGSUSED */ 821 static int 822 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh) 823 { 824 Authctxt *authctxt = ssh->authctxt; 825 Gssctxt *gssctxt; 826 size_t oidlen; 827 u_char *oidv = NULL; 828 int r; 829 830 if (authctxt == NULL) 831 fatal("input_gssapi_response: no authentication context"); 832 gssctxt = authctxt->methoddata; 833 834 /* Setup our OID */ 835 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0) 836 goto done; 837 838 if (oidlen <= 2 || 839 oidv[0] != SSH_GSS_OIDTYPE || 840 oidv[1] != oidlen - 2) { 841 debug("Badly encoded mechanism OID received"); 842 userauth(ssh, NULL); 843 goto ok; 844 } 845 846 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) 847 fatal("Server returned different OID than expected"); 848 849 if ((r = sshpkt_get_end(ssh)) != 0) 850 goto done; 851 852 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) { 853 /* Start again with next method on list */ 854 debug("Trying to start again"); 855 userauth(ssh, NULL); 856 goto ok; 857 } 858 ok: 859 r = 0; 860 done: 861 free(oidv); 862 return r; 863 } 864 865 /* ARGSUSED */ 866 static int 867 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh) 868 { 869 Authctxt *authctxt = ssh->authctxt; 870 gss_buffer_desc recv_tok; 871 u_char *p = NULL; 872 size_t len; 873 OM_uint32 status; 874 int r; 875 876 if (authctxt == NULL) 877 fatal("input_gssapi_response: no authentication context"); 878 879 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 880 (r = sshpkt_get_end(ssh)) != 0) 881 goto out; 882 883 recv_tok.value = p; 884 recv_tok.length = len; 885 status = process_gssapi_token(ssh, &recv_tok); 886 887 /* Start again with the next method in the list */ 888 if (GSS_ERROR(status)) { 889 userauth(ssh, NULL); 890 /* ok */ 891 } 892 r = 0; 893 out: 894 free(p); 895 return r; 896 } 897 898 /* ARGSUSED */ 899 static int 900 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh) 901 { 902 Authctxt *authctxt = ssh->authctxt; 903 Gssctxt *gssctxt; 904 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 905 gss_buffer_desc recv_tok; 906 OM_uint32 ms; 907 u_char *p = NULL; 908 size_t len; 909 int r; 910 911 if (authctxt == NULL) 912 fatal("input_gssapi_response: no authentication context"); 913 gssctxt = authctxt->methoddata; 914 915 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || 916 (r = sshpkt_get_end(ssh)) != 0) { 917 free(p); 918 return r; 919 } 920 921 /* Stick it into GSSAPI and see what it says */ 922 recv_tok.value = p; 923 recv_tok.length = len; 924 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, 925 &recv_tok, &send_tok, NULL); 926 free(p); 927 gss_release_buffer(&ms, &send_tok); 928 929 /* Server will be returning a failed packet after this one */ 930 return 0; 931 } 932 933 /* ARGSUSED */ 934 static int 935 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) 936 { 937 char *msg = NULL; 938 char *lang = NULL; 939 int r; 940 941 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */ 942 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */ 943 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || 944 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 945 goto out; 946 r = sshpkt_get_end(ssh); 947 debug("Server GSSAPI Error:\n%s", msg); 948 out: 949 free(msg); 950 free(lang); 951 return r; 952 } 953 #endif /* GSSAPI */ 954 955 static int 956 userauth_none(struct ssh *ssh) 957 { 958 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 959 int r; 960 961 /* initial userauth request */ 962 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 963 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 964 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 965 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 966 (r = sshpkt_send(ssh)) != 0) 967 fatal("%s: %s", __func__, ssh_err(r)); 968 return 1; 969 } 970 971 static int 972 userauth_passwd(struct ssh *ssh) 973 { 974 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 975 char *password, *prompt = NULL; 976 const char *host = options.host_key_alias ? options.host_key_alias : 977 authctxt->host; 978 int r; 979 980 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts) 981 return 0; 982 983 if (authctxt->attempt_passwd != 1) 984 error("Permission denied, please try again."); 985 986 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host); 987 password = read_passphrase(prompt, 0); 988 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 989 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 990 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 991 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 992 (r = sshpkt_put_u8(ssh, 0)) != 0 || 993 (r = sshpkt_put_cstring(ssh, password)) != 0 || 994 (r = sshpkt_add_padding(ssh, 64)) != 0 || 995 (r = sshpkt_send(ssh)) != 0) 996 fatal("%s: %s", __func__, ssh_err(r)); 997 998 free(prompt); 999 if (password != NULL) 1000 freezero(password, strlen(password)); 1001 1002 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1003 &input_userauth_passwd_changereq); 1004 1005 return 1; 1006 } 1007 1008 /* 1009 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST 1010 */ 1011 /* ARGSUSED */ 1012 static int 1013 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh) 1014 { 1015 Authctxt *authctxt = ssh->authctxt; 1016 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL; 1017 char prompt[256]; 1018 const char *host; 1019 int r; 1020 1021 debug2("input_userauth_passwd_changereq"); 1022 1023 if (authctxt == NULL) 1024 fatal("input_userauth_passwd_changereq: " 1025 "no authentication context"); 1026 host = options.host_key_alias ? options.host_key_alias : authctxt->host; 1027 1028 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 || 1029 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1030 goto out; 1031 if (strlen(info) > 0) 1032 logit("%s", info); 1033 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1034 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1035 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1036 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1037 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */ 1038 goto out; 1039 1040 snprintf(prompt, sizeof(prompt), 1041 "Enter %.30s@%.128s's old password: ", 1042 authctxt->server_user, host); 1043 password = read_passphrase(prompt, 0); 1044 if ((r = sshpkt_put_cstring(ssh, password)) != 0) 1045 goto out; 1046 1047 freezero(password, strlen(password)); 1048 password = NULL; 1049 while (password == NULL) { 1050 snprintf(prompt, sizeof(prompt), 1051 "Enter %.30s@%.128s's new password: ", 1052 authctxt->server_user, host); 1053 password = read_passphrase(prompt, RP_ALLOW_EOF); 1054 if (password == NULL) { 1055 /* bail out */ 1056 r = 0; 1057 goto out; 1058 } 1059 snprintf(prompt, sizeof(prompt), 1060 "Retype %.30s@%.128s's new password: ", 1061 authctxt->server_user, host); 1062 retype = read_passphrase(prompt, 0); 1063 if (strcmp(password, retype) != 0) { 1064 freezero(password, strlen(password)); 1065 logit("Mismatch; try again, EOF to quit."); 1066 password = NULL; 1067 } 1068 freezero(retype, strlen(retype)); 1069 } 1070 if ((r = sshpkt_put_cstring(ssh, password)) != 0 || 1071 (r = sshpkt_add_padding(ssh, 64)) != 0 || 1072 (r = sshpkt_send(ssh)) != 0) 1073 goto out; 1074 1075 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, 1076 &input_userauth_passwd_changereq); 1077 r = 0; 1078 out: 1079 if (password) 1080 freezero(password, strlen(password)); 1081 free(info); 1082 free(lang); 1083 return r; 1084 } 1085 1086 /* 1087 * Select an algorithm for publickey signatures. 1088 * Returns algorithm (caller must free) or NULL if no mutual algorithm found. 1089 * 1090 * Call with ssh==NULL to ignore server-sig-algs extension list and 1091 * only attempt with the key's base signature type. 1092 */ 1093 static char * 1094 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key) 1095 { 1096 char *allowed, *oallowed, *cp, *tmp, *alg = NULL; 1097 1098 /* 1099 * The signature algorithm will only differ from the key algorithm 1100 * for RSA keys/certs and when the server advertises support for 1101 * newer (SHA2) algorithms. 1102 */ 1103 if (ssh == NULL || ssh->kex->server_sig_algs == NULL || 1104 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) || 1105 (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) { 1106 /* Filter base key signature alg against our configuration */ 1107 return match_list(sshkey_ssh_name(key), 1108 options.pubkey_key_types, NULL); 1109 } 1110 1111 /* 1112 * For RSA keys/certs, since these might have a different sig type: 1113 * find the first entry in PubkeyAcceptedKeyTypes of the right type 1114 * that also appears in the supported signature algorithms list from 1115 * the server. 1116 */ 1117 oallowed = allowed = xstrdup(options.pubkey_key_types); 1118 while ((cp = strsep(&allowed, ",")) != NULL) { 1119 if (sshkey_type_from_name(cp) != key->type) 1120 continue; 1121 tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL); 1122 if (tmp != NULL) 1123 alg = xstrdup(cp); 1124 free(tmp); 1125 if (alg != NULL) 1126 break; 1127 } 1128 free(oallowed); 1129 return alg; 1130 } 1131 1132 static int 1133 identity_sign(struct identity *id, u_char **sigp, size_t *lenp, 1134 const u_char *data, size_t datalen, u_int compat, const char *alg) 1135 { 1136 struct sshkey *prv; 1137 int r; 1138 1139 /* The agent supports this key. */ 1140 if (id->key != NULL && id->agent_fd != -1) { 1141 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp, 1142 data, datalen, alg, compat); 1143 } 1144 1145 /* 1146 * We have already loaded the private key or the private key is 1147 * stored in external hardware. 1148 */ 1149 if (id->key != NULL && 1150 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) { 1151 if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen, 1152 alg, compat)) != 0) 1153 return r; 1154 /* 1155 * PKCS#11 tokens may not support all signature algorithms, 1156 * so check what we get back. 1157 */ 1158 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) 1159 return r; 1160 return 0; 1161 } 1162 1163 /* Load the private key from the file. */ 1164 if ((prv = load_identity_file(id)) == NULL) 1165 return SSH_ERR_KEY_NOT_FOUND; 1166 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) { 1167 error("%s: private key %s contents do not match public", 1168 __func__, id->filename); 1169 return SSH_ERR_KEY_NOT_FOUND; 1170 } 1171 r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat); 1172 sshkey_free(prv); 1173 return r; 1174 } 1175 1176 static int 1177 id_filename_matches(Identity *id, Identity *private_id) 1178 { 1179 const char *suffixes[] = { ".pub", "-cert.pub", NULL }; 1180 size_t len = strlen(id->filename), plen = strlen(private_id->filename); 1181 size_t i, slen; 1182 1183 if (strcmp(id->filename, private_id->filename) == 0) 1184 return 1; 1185 for (i = 0; suffixes[i]; i++) { 1186 slen = strlen(suffixes[i]); 1187 if (len > slen && plen == len - slen && 1188 strcmp(id->filename + (len - slen), suffixes[i]) == 0 && 1189 memcmp(id->filename, private_id->filename, plen) == 0) 1190 return 1; 1191 } 1192 return 0; 1193 } 1194 1195 static int 1196 sign_and_send_pubkey(struct ssh *ssh, Identity *id) 1197 { 1198 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1199 struct sshbuf *b = NULL; 1200 Identity *private_id, *sign_id = NULL; 1201 u_char *signature = NULL; 1202 size_t slen = 0, skip = 0; 1203 int r, fallback_sigtype, sent = 0; 1204 char *alg = NULL, *fp = NULL; 1205 const char *loc = ""; 1206 1207 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, 1208 SSH_FP_DEFAULT)) == NULL) 1209 return 0; 1210 1211 debug3("%s: %s %s", __func__, sshkey_type(id->key), fp); 1212 1213 /* 1214 * If the key is an certificate, try to find a matching private key 1215 * and use it to complete the signature. 1216 * If no such private key exists, fall back to trying the certificate 1217 * key itself in case it has a private half already loaded. 1218 * This will try to set sign_id to the private key that will perform 1219 * the signature. 1220 */ 1221 if (sshkey_is_cert(id->key)) { 1222 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1223 if (sshkey_equal_public(id->key, private_id->key) && 1224 id->key->type != private_id->key->type) { 1225 sign_id = private_id; 1226 break; 1227 } 1228 } 1229 /* 1230 * Exact key matches are preferred, but also allow 1231 * filename matches for non-PKCS#11/agent keys that 1232 * didn't load public keys. This supports the case 1233 * of keeping just a private key file and public 1234 * certificate on disk. 1235 */ 1236 if (sign_id == NULL && 1237 !id->isprivate && id->agent_fd == -1 && 1238 (id->key->flags & SSHKEY_FLAG_EXT) == 0) { 1239 TAILQ_FOREACH(private_id, &authctxt->keys, next) { 1240 if (private_id->key == NULL && 1241 id_filename_matches(id, private_id)) { 1242 sign_id = private_id; 1243 break; 1244 } 1245 } 1246 } 1247 if (sign_id != NULL) { 1248 debug2("%s: using private key \"%s\"%s for " 1249 "certificate", __func__, id->filename, 1250 id->agent_fd != -1 ? " from agent" : ""); 1251 } else { 1252 debug("%s: no separate private key for certificate " 1253 "\"%s\"", __func__, id->filename); 1254 } 1255 } 1256 1257 /* 1258 * If the above didn't select another identity to do the signing 1259 * then default to the one we started with. 1260 */ 1261 if (sign_id == NULL) 1262 sign_id = id; 1263 1264 /* assemble and sign data */ 1265 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) { 1266 free(alg); 1267 slen = 0; 1268 signature = NULL; 1269 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh, 1270 id->key)) == NULL) { 1271 error("%s: no mutual signature supported", __func__); 1272 goto out; 1273 } 1274 debug3("%s: signing using %s", __func__, alg); 1275 1276 sshbuf_free(b); 1277 if ((b = sshbuf_new()) == NULL) 1278 fatal("%s: sshbuf_new failed", __func__); 1279 if (datafellows & SSH_OLD_SESSIONID) { 1280 if ((r = sshbuf_put(b, session_id2, 1281 session_id2_len)) != 0) { 1282 fatal("%s: sshbuf_put: %s", 1283 __func__, ssh_err(r)); 1284 } 1285 } else { 1286 if ((r = sshbuf_put_string(b, session_id2, 1287 session_id2_len)) != 0) { 1288 fatal("%s: sshbuf_put_string: %s", 1289 __func__, ssh_err(r)); 1290 } 1291 } 1292 skip = sshbuf_len(b); 1293 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1294 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 1295 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 1296 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 1297 (r = sshbuf_put_u8(b, 1)) != 0 || 1298 (r = sshbuf_put_cstring(b, alg)) != 0 || 1299 (r = sshkey_puts(id->key, b)) != 0) { 1300 fatal("%s: assemble signed data: %s", 1301 __func__, ssh_err(r)); 1302 } 1303 1304 /* generate signature */ 1305 r = identity_sign(sign_id, &signature, &slen, 1306 sshbuf_ptr(b), sshbuf_len(b), datafellows, alg); 1307 if (r == 0) 1308 break; 1309 else if (r == SSH_ERR_KEY_NOT_FOUND) 1310 goto out; /* soft failure */ 1311 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED && 1312 !fallback_sigtype) { 1313 if (sign_id->agent_fd != -1) 1314 loc = "agent "; 1315 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0) 1316 loc = "token "; 1317 logit("%skey %s %s returned incorrect signature type", 1318 loc, sshkey_type(id->key), fp); 1319 continue; 1320 } 1321 error("%s: signing failed: %s", __func__, ssh_err(r)); 1322 goto out; 1323 } 1324 if (slen == 0 || signature == NULL) /* shouldn't happen */ 1325 fatal("%s: no signature", __func__); 1326 1327 /* append signature */ 1328 if ((r = sshbuf_put_string(b, signature, slen)) != 0) 1329 fatal("%s: append signature: %s", __func__, ssh_err(r)); 1330 1331 #ifdef DEBUG_PK 1332 sshbuf_dump(b, stderr); 1333 #endif 1334 /* skip session id and packet type */ 1335 if ((r = sshbuf_consume(b, skip + 1)) != 0) 1336 fatal("%s: consume: %s", __func__, ssh_err(r)); 1337 1338 /* put remaining data from buffer into packet */ 1339 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1340 (r = sshpkt_putb(ssh, b)) != 0 || 1341 (r = sshpkt_send(ssh)) != 0) 1342 fatal("%s: enqueue request: %s", __func__, ssh_err(r)); 1343 1344 /* success */ 1345 sent = 1; 1346 1347 out: 1348 free(fp); 1349 free(alg); 1350 sshbuf_free(b); 1351 freezero(signature, slen); 1352 return sent; 1353 } 1354 1355 static int 1356 send_pubkey_test(struct ssh *ssh, Identity *id) 1357 { 1358 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1359 u_char *blob = NULL; 1360 char *alg = NULL; 1361 size_t bloblen; 1362 u_int have_sig = 0; 1363 int sent = 0, r; 1364 1365 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) { 1366 debug("%s: no mutual signature algorithm", __func__); 1367 goto out; 1368 } 1369 1370 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { 1371 /* we cannot handle this key */ 1372 debug3("%s: cannot handle key", __func__); 1373 goto out; 1374 } 1375 /* register callback for USERAUTH_PK_OK message */ 1376 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); 1377 1378 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1379 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1380 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1381 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1382 (r = sshpkt_put_u8(ssh, have_sig)) != 0 || 1383 (r = sshpkt_put_cstring(ssh, alg)) != 0 || 1384 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 || 1385 (r = sshpkt_send(ssh)) != 0) 1386 fatal("%s: %s", __func__, ssh_err(r)); 1387 sent = 1; 1388 1389 out: 1390 free(alg); 1391 free(blob); 1392 return sent; 1393 } 1394 1395 static struct sshkey * 1396 load_identity_file(Identity *id) 1397 { 1398 struct sshkey *private = NULL; 1399 char prompt[300], *passphrase, *comment; 1400 int r, perm_ok = 0, quit = 0, i; 1401 struct stat st; 1402 1403 if (stat(id->filename, &st) < 0) { 1404 (id->userprovided ? logit : debug3)("no such identity: %s: %s", 1405 id->filename, strerror(errno)); 1406 return NULL; 1407 } 1408 snprintf(prompt, sizeof prompt, 1409 "Enter passphrase for key '%.100s': ", id->filename); 1410 for (i = 0; i <= options.number_of_password_prompts; i++) { 1411 if (i == 0) 1412 passphrase = ""; 1413 else { 1414 passphrase = read_passphrase(prompt, 0); 1415 if (*passphrase == '\0') { 1416 debug2("no passphrase given, try next key"); 1417 free(passphrase); 1418 break; 1419 } 1420 } 1421 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename, 1422 passphrase, &private, &comment, &perm_ok))) { 1423 case 0: 1424 break; 1425 case SSH_ERR_KEY_WRONG_PASSPHRASE: 1426 if (options.batch_mode) { 1427 quit = 1; 1428 break; 1429 } 1430 if (i != 0) 1431 debug2("bad passphrase given, try again..."); 1432 break; 1433 case SSH_ERR_SYSTEM_ERROR: 1434 if (errno == ENOENT) { 1435 debug2("Load key \"%s\": %s", 1436 id->filename, ssh_err(r)); 1437 quit = 1; 1438 break; 1439 } 1440 /* FALLTHROUGH */ 1441 default: 1442 error("Load key \"%s\": %s", id->filename, ssh_err(r)); 1443 quit = 1; 1444 break; 1445 } 1446 if (!quit && private != NULL && id->agent_fd == -1 && 1447 !(id->key && id->isprivate)) 1448 maybe_add_key_to_agent(id->filename, private, comment, 1449 passphrase); 1450 if (i > 0) 1451 freezero(passphrase, strlen(passphrase)); 1452 free(comment); 1453 if (private != NULL || quit) 1454 break; 1455 } 1456 return private; 1457 } 1458 1459 static int 1460 key_type_allowed_by_config(struct sshkey *key) 1461 { 1462 if (match_pattern_list(sshkey_ssh_name(key), 1463 options.pubkey_key_types, 0) == 1) 1464 return 1; 1465 1466 /* RSA keys/certs might be allowed by alternate signature types */ 1467 switch (key->type) { 1468 case KEY_RSA: 1469 if (match_pattern_list("rsa-sha2-512", 1470 options.pubkey_key_types, 0) == 1) 1471 return 1; 1472 if (match_pattern_list("rsa-sha2-256", 1473 options.pubkey_key_types, 0) == 1) 1474 return 1; 1475 break; 1476 case KEY_RSA_CERT: 1477 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", 1478 options.pubkey_key_types, 0) == 1) 1479 return 1; 1480 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", 1481 options.pubkey_key_types, 0) == 1) 1482 return 1; 1483 break; 1484 } 1485 return 0; 1486 } 1487 1488 1489 /* 1490 * try keys in the following order: 1491 * 1. certificates listed in the config file 1492 * 2. other input certificates 1493 * 3. agent keys that are found in the config file 1494 * 4. other agent keys 1495 * 5. keys that are only listed in the config file 1496 */ 1497 static void 1498 pubkey_prepare(Authctxt *authctxt) 1499 { 1500 struct identity *id, *id2, *tmp; 1501 struct idlist agent, files, *preferred; 1502 struct sshkey *key; 1503 int agent_fd = -1, i, r, found; 1504 size_t j; 1505 struct ssh_identitylist *idlist; 1506 char *ident; 1507 1508 TAILQ_INIT(&agent); /* keys from the agent */ 1509 TAILQ_INIT(&files); /* keys from the config file */ 1510 preferred = &authctxt->keys; 1511 TAILQ_INIT(preferred); /* preferred order of keys */ 1512 1513 /* list of keys stored in the filesystem and PKCS#11 */ 1514 for (i = 0; i < options.num_identity_files; i++) { 1515 key = options.identity_keys[i]; 1516 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) 1517 continue; 1518 options.identity_keys[i] = NULL; 1519 id = xcalloc(1, sizeof(*id)); 1520 id->agent_fd = -1; 1521 id->key = key; 1522 id->filename = xstrdup(options.identity_files[i]); 1523 id->userprovided = options.identity_file_userprovided[i]; 1524 TAILQ_INSERT_TAIL(&files, id, next); 1525 } 1526 /* list of certificates specified by user */ 1527 for (i = 0; i < options.num_certificate_files; i++) { 1528 key = options.certificates[i]; 1529 if (!sshkey_is_cert(key) || key->cert == NULL || 1530 key->cert->type != SSH2_CERT_TYPE_USER) 1531 continue; 1532 id = xcalloc(1, sizeof(*id)); 1533 id->agent_fd = -1; 1534 id->key = key; 1535 id->filename = xstrdup(options.certificate_files[i]); 1536 id->userprovided = options.certificate_file_userprovided[i]; 1537 TAILQ_INSERT_TAIL(preferred, id, next); 1538 } 1539 /* list of keys supported by the agent */ 1540 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { 1541 if (r != SSH_ERR_AGENT_NOT_PRESENT) 1542 debug("%s: ssh_get_authentication_socket: %s", 1543 __func__, ssh_err(r)); 1544 } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { 1545 if (r != SSH_ERR_AGENT_NO_IDENTITIES) 1546 debug("%s: ssh_fetch_identitylist: %s", 1547 __func__, ssh_err(r)); 1548 close(agent_fd); 1549 } else { 1550 for (j = 0; j < idlist->nkeys; j++) { 1551 found = 0; 1552 TAILQ_FOREACH(id, &files, next) { 1553 /* 1554 * agent keys from the config file are 1555 * preferred 1556 */ 1557 if (sshkey_equal(idlist->keys[j], id->key)) { 1558 TAILQ_REMOVE(&files, id, next); 1559 TAILQ_INSERT_TAIL(preferred, id, next); 1560 id->agent_fd = agent_fd; 1561 found = 1; 1562 break; 1563 } 1564 } 1565 if (!found && !options.identities_only) { 1566 id = xcalloc(1, sizeof(*id)); 1567 /* XXX "steals" key/comment from idlist */ 1568 id->key = idlist->keys[j]; 1569 id->filename = idlist->comments[j]; 1570 idlist->keys[j] = NULL; 1571 idlist->comments[j] = NULL; 1572 id->agent_fd = agent_fd; 1573 TAILQ_INSERT_TAIL(&agent, id, next); 1574 } 1575 } 1576 ssh_free_identitylist(idlist); 1577 /* append remaining agent keys */ 1578 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { 1579 TAILQ_REMOVE(&agent, id, next); 1580 TAILQ_INSERT_TAIL(preferred, id, next); 1581 } 1582 authctxt->agent_fd = agent_fd; 1583 } 1584 /* Prefer PKCS11 keys that are explicitly listed */ 1585 TAILQ_FOREACH_SAFE(id, &files, next, tmp) { 1586 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) 1587 continue; 1588 found = 0; 1589 TAILQ_FOREACH(id2, &files, next) { 1590 if (id2->key == NULL || 1591 (id2->key->flags & SSHKEY_FLAG_EXT) == 0) 1592 continue; 1593 if (sshkey_equal(id->key, id2->key)) { 1594 TAILQ_REMOVE(&files, id, next); 1595 TAILQ_INSERT_TAIL(preferred, id, next); 1596 found = 1; 1597 break; 1598 } 1599 } 1600 /* If IdentitiesOnly set and key not found then don't use it */ 1601 if (!found && options.identities_only) { 1602 TAILQ_REMOVE(&files, id, next); 1603 freezero(id, sizeof(*id)); 1604 } 1605 } 1606 /* append remaining keys from the config file */ 1607 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { 1608 TAILQ_REMOVE(&files, id, next); 1609 TAILQ_INSERT_TAIL(preferred, id, next); 1610 } 1611 /* finally, filter by PubkeyAcceptedKeyTypes */ 1612 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1613 if (id->key != NULL && !key_type_allowed_by_config(id->key)) { 1614 debug("Skipping %s key %s - " 1615 "not in PubkeyAcceptedKeyTypes", 1616 sshkey_ssh_name(id->key), id->filename); 1617 TAILQ_REMOVE(preferred, id, next); 1618 sshkey_free(id->key); 1619 free(id->filename); 1620 memset(id, 0, sizeof(*id)); 1621 continue; 1622 } 1623 } 1624 /* List the keys we plan on using */ 1625 TAILQ_FOREACH_SAFE(id, preferred, next, id2) { 1626 ident = format_identity(id); 1627 debug("Will attempt key: %s", ident); 1628 free(ident); 1629 } 1630 debug2("%s: done", __func__); 1631 } 1632 1633 static void 1634 pubkey_cleanup(struct ssh *ssh) 1635 { 1636 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1637 Identity *id; 1638 1639 if (authctxt->agent_fd != -1) { 1640 ssh_close_authentication_socket(authctxt->agent_fd); 1641 authctxt->agent_fd = -1; 1642 } 1643 for (id = TAILQ_FIRST(&authctxt->keys); id; 1644 id = TAILQ_FIRST(&authctxt->keys)) { 1645 TAILQ_REMOVE(&authctxt->keys, id, next); 1646 sshkey_free(id->key); 1647 free(id->filename); 1648 free(id); 1649 } 1650 } 1651 1652 static void 1653 pubkey_reset(Authctxt *authctxt) 1654 { 1655 Identity *id; 1656 1657 TAILQ_FOREACH(id, &authctxt->keys, next) 1658 id->tried = 0; 1659 } 1660 1661 static int 1662 try_identity(Identity *id) 1663 { 1664 if (!id->key) 1665 return (0); 1666 if (sshkey_type_plain(id->key->type) == KEY_RSA && 1667 (datafellows & SSH_BUG_RSASIGMD5) != 0) { 1668 debug("Skipped %s key %s for RSA/MD5 server", 1669 sshkey_type(id->key), id->filename); 1670 return (0); 1671 } 1672 return 1; 1673 } 1674 1675 static int 1676 userauth_pubkey(struct ssh *ssh) 1677 { 1678 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1679 Identity *id; 1680 int sent = 0; 1681 char *ident; 1682 1683 while ((id = TAILQ_FIRST(&authctxt->keys))) { 1684 if (id->tried++) 1685 return (0); 1686 /* move key to the end of the queue */ 1687 TAILQ_REMOVE(&authctxt->keys, id, next); 1688 TAILQ_INSERT_TAIL(&authctxt->keys, id, next); 1689 /* 1690 * send a test message if we have the public key. for 1691 * encrypted keys we cannot do this and have to load the 1692 * private key instead 1693 */ 1694 if (id->key != NULL) { 1695 if (try_identity(id)) { 1696 ident = format_identity(id); 1697 debug("Offering public key: %s", ident); 1698 free(ident); 1699 sent = send_pubkey_test(ssh, id); 1700 } 1701 } else { 1702 debug("Trying private key: %s", id->filename); 1703 id->key = load_identity_file(id); 1704 if (id->key != NULL) { 1705 if (try_identity(id)) { 1706 id->isprivate = 1; 1707 sent = sign_and_send_pubkey(ssh, id); 1708 } 1709 sshkey_free(id->key); 1710 id->key = NULL; 1711 id->isprivate = 0; 1712 } 1713 } 1714 if (sent) 1715 return (sent); 1716 } 1717 return (0); 1718 } 1719 1720 /* 1721 * Send userauth request message specifying keyboard-interactive method. 1722 */ 1723 static int 1724 userauth_kbdint(struct ssh *ssh) 1725 { 1726 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1727 int r; 1728 1729 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts) 1730 return 0; 1731 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ 1732 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) { 1733 debug3("userauth_kbdint: disable: no info_req_seen"); 1734 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); 1735 return 0; 1736 } 1737 1738 debug2("userauth_kbdint"); 1739 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 1740 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 1741 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 1742 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 1743 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */ 1744 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ? 1745 options.kbd_interactive_devices : "")) != 0 || 1746 (r = sshpkt_send(ssh)) != 0) 1747 fatal("%s: %s", __func__, ssh_err(r)); 1748 1749 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); 1750 return 1; 1751 } 1752 1753 /* 1754 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE 1755 */ 1756 static int 1757 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh) 1758 { 1759 Authctxt *authctxt = ssh->authctxt; 1760 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL; 1761 char *response = NULL; 1762 u_char echo = 0; 1763 u_int num_prompts, i; 1764 int r; 1765 1766 debug2("input_userauth_info_req"); 1767 1768 if (authctxt == NULL) 1769 fatal("input_userauth_info_req: no authentication context"); 1770 1771 authctxt->info_req_seen = 1; 1772 1773 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 1774 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 || 1775 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0) 1776 goto out; 1777 if (strlen(name) > 0) 1778 logit("%s", name); 1779 if (strlen(inst) > 0) 1780 logit("%s", inst); 1781 1782 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0) 1783 goto out; 1784 /* 1785 * Begin to build info response packet based on prompts requested. 1786 * We commit to providing the correct number of responses, so if 1787 * further on we run into a problem that prevents this, we have to 1788 * be sure and clean this up and send a correct error response. 1789 */ 1790 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 || 1791 (r = sshpkt_put_u32(ssh, num_prompts)) != 0) 1792 goto out; 1793 1794 debug2("input_userauth_info_req: num_prompts %d", num_prompts); 1795 for (i = 0; i < num_prompts; i++) { 1796 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 || 1797 (r = sshpkt_get_u8(ssh, &echo)) != 0) 1798 goto out; 1799 response = read_passphrase(prompt, echo ? RP_ECHO : 0); 1800 if ((r = sshpkt_put_cstring(ssh, response)) != 0) 1801 goto out; 1802 freezero(response, strlen(response)); 1803 free(prompt); 1804 response = prompt = NULL; 1805 } 1806 /* done with parsing incoming message. */ 1807 if ((r = sshpkt_get_end(ssh)) != 0 || 1808 (r = sshpkt_add_padding(ssh, 64)) != 0) 1809 goto out; 1810 r = sshpkt_send(ssh); 1811 out: 1812 if (response) 1813 freezero(response, strlen(response)); 1814 free(prompt); 1815 free(name); 1816 free(inst); 1817 free(lang); 1818 return r; 1819 } 1820 1821 static int 1822 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp, 1823 const u_char *data, size_t datalen) 1824 { 1825 struct sshbuf *b; 1826 struct stat st; 1827 pid_t pid; 1828 int r, to[2], from[2], status; 1829 int sock = ssh_packet_get_connection_in(ssh); 1830 u_char rversion = 0, version = 2; 1831 void (*osigchld)(int); 1832 1833 *sigp = NULL; 1834 *lenp = 0; 1835 1836 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { 1837 error("%s: not installed: %s", __func__, strerror(errno)); 1838 return -1; 1839 } 1840 if (fflush(stdout) != 0) { 1841 error("%s: fflush: %s", __func__, strerror(errno)); 1842 return -1; 1843 } 1844 if (pipe(to) < 0) { 1845 error("%s: pipe: %s", __func__, strerror(errno)); 1846 return -1; 1847 } 1848 if (pipe(from) < 0) { 1849 error("%s: pipe: %s", __func__, strerror(errno)); 1850 return -1; 1851 } 1852 if ((pid = fork()) < 0) { 1853 error("%s: fork: %s", __func__, strerror(errno)); 1854 return -1; 1855 } 1856 osigchld = signal(SIGCHLD, SIG_DFL); 1857 if (pid == 0) { 1858 close(from[0]); 1859 if (dup2(from[1], STDOUT_FILENO) < 0) 1860 fatal("%s: dup2: %s", __func__, strerror(errno)); 1861 close(to[1]); 1862 if (dup2(to[0], STDIN_FILENO) < 0) 1863 fatal("%s: dup2: %s", __func__, strerror(errno)); 1864 close(from[1]); 1865 close(to[0]); 1866 1867 if (dup2(sock, STDERR_FILENO + 1) < 0) 1868 fatal("%s: dup2: %s", __func__, strerror(errno)); 1869 sock = STDERR_FILENO + 1; 1870 fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ 1871 closefrom(sock + 1); 1872 1873 debug3("%s: [child] pid=%ld, exec %s", 1874 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN); 1875 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); 1876 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN, 1877 strerror(errno)); 1878 } 1879 close(from[1]); 1880 close(to[0]); 1881 sock = STDERR_FILENO + 1; 1882 1883 if ((b = sshbuf_new()) == NULL) 1884 fatal("%s: sshbuf_new failed", __func__); 1885 /* send # of sock, data to be signed */ 1886 if ((r = sshbuf_put_u32(b, sock)) != 0 || 1887 (r = sshbuf_put_string(b, data, datalen)) != 0) 1888 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1889 if (ssh_msg_send(to[1], version, b) == -1) 1890 fatal("%s: couldn't send request", __func__); 1891 sshbuf_reset(b); 1892 r = ssh_msg_recv(from[0], b); 1893 close(from[0]); 1894 close(to[1]); 1895 if (r < 0) { 1896 error("%s: no reply", __func__); 1897 goto fail; 1898 } 1899 1900 errno = 0; 1901 while (waitpid(pid, &status, 0) < 0) { 1902 if (errno != EINTR) { 1903 error("%s: waitpid %ld: %s", 1904 __func__, (long)pid, strerror(errno)); 1905 goto fail; 1906 } 1907 } 1908 if (!WIFEXITED(status)) { 1909 error("%s: exited abnormally", __func__); 1910 goto fail; 1911 } 1912 if (WEXITSTATUS(status) != 0) { 1913 error("%s: exited with status %d", 1914 __func__, WEXITSTATUS(status)); 1915 goto fail; 1916 } 1917 if ((r = sshbuf_get_u8(b, &rversion)) != 0) { 1918 error("%s: buffer error: %s", __func__, ssh_err(r)); 1919 goto fail; 1920 } 1921 if (rversion != version) { 1922 error("%s: bad version", __func__); 1923 goto fail; 1924 } 1925 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { 1926 error("%s: buffer error: %s", __func__, ssh_err(r)); 1927 fail: 1928 signal(SIGCHLD, osigchld); 1929 sshbuf_free(b); 1930 return -1; 1931 } 1932 signal(SIGCHLD, osigchld); 1933 sshbuf_free(b); 1934 1935 return 0; 1936 } 1937 1938 static int 1939 userauth_hostbased(struct ssh *ssh) 1940 { 1941 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1942 struct sshkey *private = NULL; 1943 struct sshbuf *b = NULL; 1944 u_char *sig = NULL, *keyblob = NULL; 1945 char *fp = NULL, *chost = NULL, *lname = NULL; 1946 size_t siglen = 0, keylen = 0; 1947 int i, r, success = 0; 1948 1949 if (authctxt->ktypes == NULL) { 1950 authctxt->oktypes = xstrdup(options.hostbased_key_types); 1951 authctxt->ktypes = authctxt->oktypes; 1952 } 1953 1954 /* 1955 * Work through each listed type pattern in HostbasedKeyTypes, 1956 * trying each hostkey that matches the type in turn. 1957 */ 1958 for (;;) { 1959 if (authctxt->active_ktype == NULL) 1960 authctxt->active_ktype = strsep(&authctxt->ktypes, ","); 1961 if (authctxt->active_ktype == NULL || 1962 *authctxt->active_ktype == '\0') 1963 break; 1964 debug3("%s: trying key type %s", __func__, 1965 authctxt->active_ktype); 1966 1967 /* check for a useful key */ 1968 private = NULL; 1969 for (i = 0; i < authctxt->sensitive->nkeys; i++) { 1970 if (authctxt->sensitive->keys[i] == NULL || 1971 authctxt->sensitive->keys[i]->type == KEY_UNSPEC) 1972 continue; 1973 if (match_pattern_list( 1974 sshkey_ssh_name(authctxt->sensitive->keys[i]), 1975 authctxt->active_ktype, 0) != 1) 1976 continue; 1977 /* we take and free the key */ 1978 private = authctxt->sensitive->keys[i]; 1979 authctxt->sensitive->keys[i] = NULL; 1980 break; 1981 } 1982 /* Found one */ 1983 if (private != NULL) 1984 break; 1985 /* No more keys of this type; advance */ 1986 authctxt->active_ktype = NULL; 1987 } 1988 if (private == NULL) { 1989 free(authctxt->oktypes); 1990 authctxt->oktypes = authctxt->ktypes = NULL; 1991 authctxt->active_ktype = NULL; 1992 debug("No more client hostkeys for hostbased authentication."); 1993 goto out; 1994 } 1995 1996 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash, 1997 SSH_FP_DEFAULT)) == NULL) { 1998 error("%s: sshkey_fingerprint failed", __func__); 1999 goto out; 2000 } 2001 debug("%s: trying hostkey %s %s", 2002 __func__, sshkey_ssh_name(private), fp); 2003 2004 /* figure out a name for the client host */ 2005 lname = get_local_name(ssh_packet_get_connection_in(ssh)); 2006 if (lname == NULL) { 2007 error("%s: cannot get local ipaddr/name", __func__); 2008 goto out; 2009 } 2010 2011 /* XXX sshbuf_put_stringf? */ 2012 xasprintf(&chost, "%s.", lname); 2013 debug2("%s: chost %s", __func__, chost); 2014 2015 /* construct data */ 2016 if ((b = sshbuf_new()) == NULL) { 2017 error("%s: sshbuf_new failed", __func__); 2018 goto out; 2019 } 2020 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { 2021 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 2022 goto out; 2023 } 2024 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 || 2025 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2026 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 || 2027 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 || 2028 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 || 2029 (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 || 2030 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 || 2031 (r = sshbuf_put_cstring(b, chost)) != 0 || 2032 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) { 2033 error("%s: buffer error: %s", __func__, ssh_err(r)); 2034 goto out; 2035 } 2036 2037 #ifdef DEBUG_PK 2038 sshbuf_dump(b, stderr); 2039 #endif 2040 if ((r = ssh_keysign(ssh, private, &sig, &siglen, 2041 sshbuf_ptr(b), sshbuf_len(b))) != 0) { 2042 error("sign using hostkey %s %s failed", 2043 sshkey_ssh_name(private), fp); 2044 goto out; 2045 } 2046 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || 2047 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || 2048 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || 2049 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || 2050 (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 || 2051 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 || 2052 (r = sshpkt_put_cstring(ssh, chost)) != 0 || 2053 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 || 2054 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 || 2055 (r = sshpkt_send(ssh)) != 0) { 2056 error("%s: packet error: %s", __func__, ssh_err(r)); 2057 goto out; 2058 } 2059 success = 1; 2060 2061 out: 2062 if (sig != NULL) 2063 freezero(sig, siglen); 2064 free(keyblob); 2065 free(lname); 2066 free(fp); 2067 free(chost); 2068 sshkey_free(private); 2069 sshbuf_free(b); 2070 2071 return success; 2072 } 2073 2074 /* find auth method */ 2075 2076 /* 2077 * given auth method name, if configurable options permit this method fill 2078 * in auth_ident field and return true, otherwise return false. 2079 */ 2080 static int 2081 authmethod_is_enabled(Authmethod *method) 2082 { 2083 if (method == NULL) 2084 return 0; 2085 /* return false if options indicate this method is disabled */ 2086 if (method->enabled == NULL || *method->enabled == 0) 2087 return 0; 2088 /* return false if batch mode is enabled but method needs interactive mode */ 2089 if (method->batch_flag != NULL && *method->batch_flag != 0) 2090 return 0; 2091 return 1; 2092 } 2093 2094 static Authmethod * 2095 authmethod_lookup(const char *name) 2096 { 2097 Authmethod *method = NULL; 2098 if (name != NULL) 2099 for (method = authmethods; method->name != NULL; method++) 2100 if (strcmp(name, method->name) == 0) 2101 return method; 2102 debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); 2103 return NULL; 2104 } 2105 2106 /* XXX internal state */ 2107 static Authmethod *current = NULL; 2108 static char *supported = NULL; 2109 static char *preferred = NULL; 2110 2111 /* 2112 * Given the authentication method list sent by the server, return the 2113 * next method we should try. If the server initially sends a nil list, 2114 * use a built-in default list. 2115 */ 2116 static Authmethod * 2117 authmethod_get(char *authlist) 2118 { 2119 char *name = NULL; 2120 u_int next; 2121 2122 /* Use a suitable default if we're passed a nil list. */ 2123 if (authlist == NULL || strlen(authlist) == 0) 2124 authlist = options.preferred_authentications; 2125 2126 if (supported == NULL || strcmp(authlist, supported) != 0) { 2127 debug3("start over, passed a different list %s", authlist); 2128 free(supported); 2129 supported = xstrdup(authlist); 2130 preferred = options.preferred_authentications; 2131 debug3("preferred %s", preferred); 2132 current = NULL; 2133 } else if (current != NULL && authmethod_is_enabled(current)) 2134 return current; 2135 2136 for (;;) { 2137 if ((name = match_list(preferred, supported, &next)) == NULL) { 2138 debug("No more authentication methods to try."); 2139 current = NULL; 2140 return NULL; 2141 } 2142 preferred += next; 2143 debug3("authmethod_lookup %s", name); 2144 debug3("remaining preferred: %s", preferred); 2145 if ((current = authmethod_lookup(name)) != NULL && 2146 authmethod_is_enabled(current)) { 2147 debug3("authmethod_is_enabled %s", name); 2148 debug("Next authentication method: %s", name); 2149 free(name); 2150 return current; 2151 } 2152 free(name); 2153 } 2154 } 2155 2156 static char * 2157 authmethods_get(void) 2158 { 2159 Authmethod *method = NULL; 2160 struct sshbuf *b; 2161 char *list; 2162 int r; 2163 2164 if ((b = sshbuf_new()) == NULL) 2165 fatal("%s: sshbuf_new failed", __func__); 2166 for (method = authmethods; method->name != NULL; method++) { 2167 if (authmethod_is_enabled(method)) { 2168 if ((r = sshbuf_putf(b, "%s%s", 2169 sshbuf_len(b) ? "," : "", method->name)) != 0) 2170 fatal("%s: buffer error: %s", 2171 __func__, ssh_err(r)); 2172 } 2173 } 2174 if ((list = sshbuf_dup_string(b)) == NULL) 2175 fatal("%s: sshbuf_dup_string failed", __func__); 2176 sshbuf_free(b); 2177 return list; 2178 } 2179