1 /* $OpenBSD: ssh-agent.c,v 1.267 2020/11/08 22:37:24 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include <sys/types.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/resource.h> 41 #include <sys/socket.h> 42 #include <sys/stat.h> 43 #include <sys/un.h> 44 #include <sys/wait.h> 45 46 #ifdef WITH_OPENSSL 47 #include <openssl/evp.h> 48 #endif 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <paths.h> 53 #include <poll.h> 54 #include <signal.h> 55 #include <stdlib.h> 56 #include <stdio.h> 57 #include <string.h> 58 #include <stdarg.h> 59 #include <limits.h> 60 #include <time.h> 61 #include <unistd.h> 62 #include <util.h> 63 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh2.h" 67 #include "sshbuf.h" 68 #include "sshkey.h" 69 #include "authfd.h" 70 #include "compat.h" 71 #include "log.h" 72 #include "misc.h" 73 #include "digest.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "msg.h" 77 #include "ssherr.h" 78 #include "pathnames.h" 79 #include "ssh-pkcs11.h" 80 #include "sk-api.h" 81 82 #ifndef DEFAULT_ALLOWED_PROVIDERS 83 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 84 #endif 85 86 /* Maximum accepted message length */ 87 #define AGENT_MAX_LEN (256*1024) 88 /* Maximum bytes to read from client socket */ 89 #define AGENT_RBUF_LEN (4096) 90 91 typedef enum { 92 AUTH_UNUSED, 93 AUTH_SOCKET, 94 AUTH_CONNECTION 95 } sock_type; 96 97 typedef struct { 98 int fd; 99 sock_type type; 100 struct sshbuf *input; 101 struct sshbuf *output; 102 struct sshbuf *request; 103 } SocketEntry; 104 105 u_int sockets_alloc = 0; 106 SocketEntry *sockets = NULL; 107 108 typedef struct identity { 109 TAILQ_ENTRY(identity) next; 110 struct sshkey *key; 111 char *comment; 112 char *provider; 113 time_t death; 114 u_int confirm; 115 char *sk_provider; 116 } Identity; 117 118 struct idtable { 119 int nentries; 120 TAILQ_HEAD(idqueue, identity) idlist; 121 }; 122 123 /* private key table */ 124 struct idtable *idtab; 125 126 int max_fd = 0; 127 128 /* pid of shell == parent of agent */ 129 pid_t parent_pid = -1; 130 time_t parent_alive_interval = 0; 131 132 /* pid of process for which cleanup_socket is applicable */ 133 pid_t cleanup_pid = 0; 134 135 /* pathname and directory for AUTH_SOCKET */ 136 char socket_name[PATH_MAX]; 137 char socket_dir[PATH_MAX]; 138 139 /* Pattern-list of allowed PKCS#11/Security key paths */ 140 static char *allowed_providers; 141 142 /* locking */ 143 #define LOCK_SIZE 32 144 #define LOCK_SALT_SIZE 16 145 #define LOCK_ROUNDS 1 146 int locked = 0; 147 u_char lock_pwhash[LOCK_SIZE]; 148 u_char lock_salt[LOCK_SALT_SIZE]; 149 150 extern char *__progname; 151 152 /* Default lifetime in seconds (0 == forever) */ 153 static long lifetime = 0; 154 155 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 156 157 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 158 static int restrict_websafe = 1; 159 160 static void 161 close_socket(SocketEntry *e) 162 { 163 close(e->fd); 164 e->fd = -1; 165 e->type = AUTH_UNUSED; 166 sshbuf_free(e->input); 167 sshbuf_free(e->output); 168 sshbuf_free(e->request); 169 } 170 171 static void 172 idtab_init(void) 173 { 174 idtab = xcalloc(1, sizeof(*idtab)); 175 TAILQ_INIT(&idtab->idlist); 176 idtab->nentries = 0; 177 } 178 179 static void 180 free_identity(Identity *id) 181 { 182 sshkey_free(id->key); 183 free(id->provider); 184 free(id->comment); 185 free(id->sk_provider); 186 free(id); 187 } 188 189 /* return matching private key for given public key */ 190 static Identity * 191 lookup_identity(struct sshkey *key) 192 { 193 Identity *id; 194 195 TAILQ_FOREACH(id, &idtab->idlist, next) { 196 if (sshkey_equal(key, id->key)) 197 return (id); 198 } 199 return (NULL); 200 } 201 202 /* Check confirmation of keysign request */ 203 static int 204 confirm_key(Identity *id) 205 { 206 char *p; 207 int ret = -1; 208 209 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 210 if (p != NULL && 211 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 212 id->comment, p)) 213 ret = 0; 214 free(p); 215 216 return (ret); 217 } 218 219 static void 220 send_status(SocketEntry *e, int success) 221 { 222 int r; 223 224 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 225 (r = sshbuf_put_u8(e->output, success ? 226 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 227 fatal_fr(r, "compose"); 228 } 229 230 /* send list of supported public keys to 'client' */ 231 static void 232 process_request_identities(SocketEntry *e) 233 { 234 Identity *id; 235 struct sshbuf *msg; 236 int r; 237 238 if ((msg = sshbuf_new()) == NULL) 239 fatal_f("sshbuf_new failed"); 240 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 241 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 242 fatal_fr(r, "compose"); 243 TAILQ_FOREACH(id, &idtab->idlist, next) { 244 if ((r = sshkey_puts_opts(id->key, msg, SSHKEY_SERIALIZE_INFO)) 245 != 0 || 246 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 247 error_fr(r, "compose key/comment"); 248 continue; 249 } 250 } 251 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 252 fatal_fr(r, "enqueue"); 253 sshbuf_free(msg); 254 } 255 256 257 static char * 258 agent_decode_alg(struct sshkey *key, u_int flags) 259 { 260 if (key->type == KEY_RSA) { 261 if (flags & SSH_AGENT_RSA_SHA2_256) 262 return "rsa-sha2-256"; 263 else if (flags & SSH_AGENT_RSA_SHA2_512) 264 return "rsa-sha2-512"; 265 } else if (key->type == KEY_RSA_CERT) { 266 if (flags & SSH_AGENT_RSA_SHA2_256) 267 return "rsa-sha2-256-cert-v01@openssh.com"; 268 else if (flags & SSH_AGENT_RSA_SHA2_512) 269 return "rsa-sha2-512-cert-v01@openssh.com"; 270 } 271 return NULL; 272 } 273 274 /* 275 * This function inspects a message to be signed by a FIDO key that has a 276 * web-like application string (i.e. one that does not begin with "ssh:". 277 * It checks that the message is one of those expected for SSH operations 278 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 279 * for the web. 280 */ 281 static int 282 check_websafe_message_contents(struct sshkey *key, 283 const u_char *msg, size_t len) 284 { 285 int matched = 0; 286 struct sshbuf *b; 287 u_char m, n; 288 char *cp1 = NULL, *cp2 = NULL; 289 int r; 290 struct sshkey *mkey = NULL; 291 292 if ((b = sshbuf_from(msg, len)) == NULL) 293 fatal_f("sshbuf_new"); 294 295 /* SSH userauth request */ 296 if ((r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* sess_id */ 297 (r = sshbuf_get_u8(b, &m)) == 0 && /* SSH2_MSG_USERAUTH_REQUEST */ 298 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* server user */ 299 (r = sshbuf_get_cstring(b, &cp1, NULL)) == 0 && /* service */ 300 (r = sshbuf_get_cstring(b, &cp2, NULL)) == 0 && /* method */ 301 (r = sshbuf_get_u8(b, &n)) == 0 && /* sig-follows */ 302 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* alg */ 303 (r = sshkey_froms(b, &mkey)) == 0 && /* key */ 304 sshbuf_len(b) == 0) { 305 debug_f("parsed userauth"); 306 if (m == SSH2_MSG_USERAUTH_REQUEST && n == 1 && 307 strcmp(cp1, "ssh-connection") == 0 && 308 strcmp(cp2, "publickey") == 0 && 309 sshkey_equal(key, mkey)) { 310 debug_f("well formed userauth"); 311 matched = 1; 312 } 313 } 314 free(cp1); 315 free(cp2); 316 sshkey_free(mkey); 317 sshbuf_free(b); 318 if (matched) 319 return 1; 320 321 if ((b = sshbuf_from(msg, len)) == NULL) 322 fatal_f("sshbuf_new"); 323 cp1 = cp2 = NULL; 324 mkey = NULL; 325 326 /* SSHSIG */ 327 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) == 0 && 328 (r = sshbuf_consume(b, 6)) == 0 && 329 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* namespace */ 330 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* reserved */ 331 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* hashalg */ 332 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* H(msg) */ 333 sshbuf_len(b) == 0) { 334 debug_f("parsed sshsig"); 335 matched = 1; 336 } 337 338 sshbuf_free(b); 339 if (matched) 340 return 1; 341 342 /* XXX CA signature operation */ 343 344 error("web-origin key attempting to sign non-SSH message"); 345 return 0; 346 } 347 348 /* ssh2 only */ 349 static void 350 process_sign_request2(SocketEntry *e) 351 { 352 const u_char *data; 353 u_char *signature = NULL; 354 size_t dlen, slen = 0; 355 u_int compat = 0, flags; 356 int r, ok = -1; 357 char *fp = NULL; 358 struct sshbuf *msg; 359 struct sshkey *key = NULL; 360 struct identity *id; 361 struct notifier_ctx *notifier = NULL; 362 363 if ((msg = sshbuf_new()) == NULL) 364 fatal_f("sshbuf_new failed"); 365 if ((r = sshkey_froms(e->request, &key)) != 0 || 366 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 367 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 368 error_fr(r, "parse"); 369 goto send; 370 } 371 372 if ((id = lookup_identity(key)) == NULL) { 373 verbose_f("%s key not found", sshkey_type(key)); 374 goto send; 375 } 376 if (id->confirm && confirm_key(id) != 0) { 377 verbose_f("user refused key"); 378 goto send; 379 } 380 if (sshkey_is_sk(id->key)) { 381 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 382 !check_websafe_message_contents(key, data, dlen)) { 383 /* error already logged */ 384 goto send; 385 } 386 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 387 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 388 SSH_FP_DEFAULT)) == NULL) 389 fatal_f("fingerprint failed"); 390 notifier = notify_start(0, 391 "Confirm user presence for key %s %s", 392 sshkey_type(id->key), fp); 393 } 394 } 395 /* XXX support PIN required FIDO keys */ 396 if ((r = sshkey_sign(id->key, &signature, &slen, 397 data, dlen, agent_decode_alg(key, flags), 398 id->sk_provider, NULL, compat)) != 0) { 399 error_fr(r, "sshkey_sign"); 400 goto send; 401 } 402 /* Success */ 403 ok = 0; 404 send: 405 notify_complete(notifier, "User presence confirmed"); 406 sshkey_free(key); 407 free(fp); 408 if (ok == 0) { 409 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 410 (r = sshbuf_put_string(msg, signature, slen)) != 0) 411 fatal_fr(r, "compose"); 412 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 413 fatal_fr(r, "compose failure"); 414 415 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 416 fatal_fr(r, "enqueue"); 417 418 sshbuf_free(msg); 419 free(signature); 420 } 421 422 /* shared */ 423 static void 424 process_remove_identity(SocketEntry *e) 425 { 426 int r, success = 0; 427 struct sshkey *key = NULL; 428 Identity *id; 429 430 if ((r = sshkey_froms(e->request, &key)) != 0) { 431 error_fr(r, "parse key"); 432 goto done; 433 } 434 if ((id = lookup_identity(key)) == NULL) { 435 debug_f("key not found"); 436 goto done; 437 } 438 /* We have this key, free it. */ 439 if (idtab->nentries < 1) 440 fatal_f("internal error: nentries %d", idtab->nentries); 441 TAILQ_REMOVE(&idtab->idlist, id, next); 442 free_identity(id); 443 idtab->nentries--; 444 sshkey_free(key); 445 success = 1; 446 done: 447 send_status(e, success); 448 } 449 450 static void 451 process_remove_all_identities(SocketEntry *e) 452 { 453 Identity *id; 454 455 /* Loop over all identities and clear the keys. */ 456 for (id = TAILQ_FIRST(&idtab->idlist); id; 457 id = TAILQ_FIRST(&idtab->idlist)) { 458 TAILQ_REMOVE(&idtab->idlist, id, next); 459 free_identity(id); 460 } 461 462 /* Mark that there are no identities. */ 463 idtab->nentries = 0; 464 465 /* Send success. */ 466 send_status(e, 1); 467 } 468 469 /* removes expired keys and returns number of seconds until the next expiry */ 470 static time_t 471 reaper(void) 472 { 473 time_t deadline = 0, now = monotime(); 474 Identity *id, *nxt; 475 476 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 477 nxt = TAILQ_NEXT(id, next); 478 if (id->death == 0) 479 continue; 480 if (now >= id->death) { 481 debug("expiring key '%s'", id->comment); 482 TAILQ_REMOVE(&idtab->idlist, id, next); 483 free_identity(id); 484 idtab->nentries--; 485 } else 486 deadline = (deadline == 0) ? id->death : 487 MINIMUM(deadline, id->death); 488 } 489 if (deadline == 0 || deadline <= now) 490 return 0; 491 else 492 return (deadline - now); 493 } 494 495 static void 496 process_add_identity(SocketEntry *e) 497 { 498 Identity *id; 499 int success = 0, confirm = 0; 500 u_int seconds = 0, maxsign; 501 char *fp, *comment = NULL, *ext_name = NULL, *sk_provider = NULL; 502 char canonical_provider[PATH_MAX]; 503 time_t death = 0; 504 struct sshkey *k = NULL; 505 u_char ctype; 506 int r = SSH_ERR_INTERNAL_ERROR; 507 508 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 509 k == NULL || 510 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 511 error_fr(r, "parse"); 512 goto err; 513 } 514 while (sshbuf_len(e->request)) { 515 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 516 error_fr(r, "parse constraint type"); 517 goto err; 518 } 519 switch (ctype) { 520 case SSH_AGENT_CONSTRAIN_LIFETIME: 521 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 522 error_fr(r, "parse lifetime constraint"); 523 goto err; 524 } 525 death = monotime() + seconds; 526 break; 527 case SSH_AGENT_CONSTRAIN_CONFIRM: 528 confirm = 1; 529 break; 530 case SSH_AGENT_CONSTRAIN_MAXSIGN: 531 if ((r = sshbuf_get_u32(e->request, &maxsign)) != 0) { 532 error_fr(r, "parse maxsign constraint"); 533 goto err; 534 } 535 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 536 error_fr(r, "enable maxsign"); 537 goto err; 538 } 539 break; 540 case SSH_AGENT_CONSTRAIN_EXTENSION: 541 if ((r = sshbuf_get_cstring(e->request, 542 &ext_name, NULL)) != 0) { 543 error_fr(r, "parse constraint extension"); 544 goto err; 545 } 546 debug_f("constraint ext %s", ext_name); 547 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 548 if (sk_provider != NULL) { 549 error("%s already set", ext_name); 550 goto err; 551 } 552 if ((r = sshbuf_get_cstring(e->request, 553 &sk_provider, NULL)) != 0) { 554 error_fr(r, "parse %s", ext_name); 555 goto err; 556 } 557 } else { 558 error_f("unsupported constraint \"%s\"", 559 ext_name); 560 goto err; 561 } 562 free(ext_name); 563 break; 564 default: 565 error_f("Unknown constraint %d", ctype); 566 err: 567 free(sk_provider); 568 free(ext_name); 569 sshbuf_reset(e->request); 570 free(comment); 571 sshkey_free(k); 572 goto send; 573 } 574 } 575 if (sk_provider != NULL) { 576 if (!sshkey_is_sk(k)) { 577 error("Cannot add provider: %s is not an " 578 "authenticator-hosted key", sshkey_type(k)); 579 free(sk_provider); 580 goto send; 581 } 582 if (strcasecmp(sk_provider, "internal") == 0) { 583 debug_f("internal provider"); 584 } else { 585 if (realpath(sk_provider, canonical_provider) == NULL) { 586 verbose("failed provider \"%.100s\": " 587 "realpath: %s", sk_provider, 588 strerror(errno)); 589 free(sk_provider); 590 goto send; 591 } 592 free(sk_provider); 593 sk_provider = xstrdup(canonical_provider); 594 if (match_pattern_list(sk_provider, 595 allowed_providers, 0) != 1) { 596 error("Refusing add key: " 597 "provider %s not allowed", sk_provider); 598 free(sk_provider); 599 goto send; 600 } 601 } 602 } 603 if ((r = sshkey_shield_private(k)) != 0) { 604 error_fr(r, "shield private"); 605 goto err; 606 } 607 608 success = 1; 609 if (lifetime && !death) 610 death = monotime() + lifetime; 611 if ((id = lookup_identity(k)) == NULL) { 612 id = xcalloc(1, sizeof(Identity)); 613 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 614 /* Increment the number of identities. */ 615 idtab->nentries++; 616 } else { 617 /* key state might have been updated */ 618 sshkey_free(id->key); 619 free(id->comment); 620 free(id->sk_provider); 621 } 622 id->key = k; 623 id->comment = comment; 624 id->death = death; 625 id->confirm = confirm; 626 id->sk_provider = sk_provider; 627 628 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 629 SSH_FP_DEFAULT)) == NULL) 630 fatal_f("sshkey_fingerprint failed"); 631 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 632 "(provider: %s)", sshkey_ssh_name(k), fp, comment, 633 seconds, confirm, sk_provider == NULL ? "none" : sk_provider); 634 free(fp); 635 send: 636 send_status(e, success); 637 } 638 639 /* XXX todo: encrypt sensitive data with passphrase */ 640 static void 641 process_lock_agent(SocketEntry *e, int lock) 642 { 643 int r, success = 0, delay; 644 char *passwd; 645 u_char passwdhash[LOCK_SIZE]; 646 static u_int fail_count = 0; 647 size_t pwlen; 648 649 /* 650 * This is deliberately fatal: the user has requested that we lock, 651 * but we can't parse their request properly. The only safe thing to 652 * do is abort. 653 */ 654 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 655 fatal_fr(r, "parse"); 656 if (pwlen == 0) { 657 debug("empty password not supported"); 658 } else if (locked && !lock) { 659 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 660 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 661 fatal("bcrypt_pbkdf"); 662 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 663 debug("agent unlocked"); 664 locked = 0; 665 fail_count = 0; 666 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 667 success = 1; 668 } else { 669 /* delay in 0.1s increments up to 10s */ 670 if (fail_count < 100) 671 fail_count++; 672 delay = 100000 * fail_count; 673 debug("unlock failed, delaying %0.1lf seconds", 674 (double)delay/1000000); 675 usleep(delay); 676 } 677 explicit_bzero(passwdhash, sizeof(passwdhash)); 678 } else if (!locked && lock) { 679 debug("agent locked"); 680 locked = 1; 681 arc4random_buf(lock_salt, sizeof(lock_salt)); 682 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 683 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 684 fatal("bcrypt_pbkdf"); 685 success = 1; 686 } 687 freezero(passwd, pwlen); 688 send_status(e, success); 689 } 690 691 static void 692 no_identities(SocketEntry *e) 693 { 694 struct sshbuf *msg; 695 int r; 696 697 if ((msg = sshbuf_new()) == NULL) 698 fatal_f("sshbuf_new failed"); 699 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 700 (r = sshbuf_put_u32(msg, 0)) != 0 || 701 (r = sshbuf_put_stringb(e->output, msg)) != 0) 702 fatal_fr(r, "compose"); 703 sshbuf_free(msg); 704 } 705 706 #ifdef ENABLE_PKCS11 707 static void 708 process_add_smartcard_key(SocketEntry *e) 709 { 710 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 711 char **comments = NULL; 712 int r, i, count = 0, success = 0, confirm = 0; 713 u_int seconds; 714 time_t death = 0; 715 u_char type; 716 struct sshkey **keys = NULL, *k; 717 Identity *id; 718 719 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 720 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 721 error_fr(r, "parse"); 722 goto send; 723 } 724 725 while (sshbuf_len(e->request)) { 726 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 727 error_fr(r, "parse type"); 728 goto send; 729 } 730 switch (type) { 731 case SSH_AGENT_CONSTRAIN_LIFETIME: 732 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 733 error_fr(r, "parse lifetime"); 734 goto send; 735 } 736 death = monotime() + seconds; 737 break; 738 case SSH_AGENT_CONSTRAIN_CONFIRM: 739 confirm = 1; 740 break; 741 default: 742 error_f("Unknown constraint type %d", type); 743 goto send; 744 } 745 } 746 if (realpath(provider, canonical_provider) == NULL) { 747 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 748 provider, strerror(errno)); 749 goto send; 750 } 751 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 752 verbose("refusing PKCS#11 add of \"%.100s\": " 753 "provider not allowed", canonical_provider); 754 goto send; 755 } 756 debug_f("add %.100s", canonical_provider); 757 if (lifetime && !death) 758 death = monotime() + lifetime; 759 760 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 761 for (i = 0; i < count; i++) { 762 k = keys[i]; 763 if (lookup_identity(k) == NULL) { 764 id = xcalloc(1, sizeof(Identity)); 765 id->key = k; 766 keys[i] = NULL; /* transferred */ 767 id->provider = xstrdup(canonical_provider); 768 if (*comments[i] != '\0') { 769 id->comment = comments[i]; 770 comments[i] = NULL; /* transferred */ 771 } else { 772 id->comment = xstrdup(canonical_provider); 773 } 774 id->death = death; 775 id->confirm = confirm; 776 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 777 idtab->nentries++; 778 success = 1; 779 } 780 sshkey_free(keys[i]); 781 free(comments[i]); 782 } 783 send: 784 free(pin); 785 free(provider); 786 free(keys); 787 free(comments); 788 send_status(e, success); 789 } 790 791 static void 792 process_remove_smartcard_key(SocketEntry *e) 793 { 794 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 795 int r, success = 0; 796 Identity *id, *nxt; 797 798 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 799 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 800 error_fr(r, "parse"); 801 goto send; 802 } 803 free(pin); 804 805 if (realpath(provider, canonical_provider) == NULL) { 806 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 807 provider, strerror(errno)); 808 goto send; 809 } 810 811 debug_f("remove %.100s", canonical_provider); 812 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 813 nxt = TAILQ_NEXT(id, next); 814 /* Skip file--based keys */ 815 if (id->provider == NULL) 816 continue; 817 if (!strcmp(canonical_provider, id->provider)) { 818 TAILQ_REMOVE(&idtab->idlist, id, next); 819 free_identity(id); 820 idtab->nentries--; 821 } 822 } 823 if (pkcs11_del_provider(canonical_provider) == 0) 824 success = 1; 825 else 826 error_f("pkcs11_del_provider failed"); 827 send: 828 free(provider); 829 send_status(e, success); 830 } 831 #endif /* ENABLE_PKCS11 */ 832 833 /* 834 * dispatch incoming message. 835 * returns 1 on success, 0 for incomplete messages or -1 on error. 836 */ 837 static int 838 process_message(u_int socknum) 839 { 840 u_int msg_len; 841 u_char type; 842 const u_char *cp; 843 int r; 844 SocketEntry *e; 845 846 if (socknum >= sockets_alloc) 847 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 848 e = &sockets[socknum]; 849 850 if (sshbuf_len(e->input) < 5) 851 return 0; /* Incomplete message header. */ 852 cp = sshbuf_ptr(e->input); 853 msg_len = PEEK_U32(cp); 854 if (msg_len > AGENT_MAX_LEN) { 855 debug_f("socket %u (fd=%d) message too long %u > %u", 856 socknum, e->fd, msg_len, AGENT_MAX_LEN); 857 return -1; 858 } 859 if (sshbuf_len(e->input) < msg_len + 4) 860 return 0; /* Incomplete message body. */ 861 862 /* move the current input to e->request */ 863 sshbuf_reset(e->request); 864 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 865 (r = sshbuf_get_u8(e->request, &type)) != 0) { 866 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 867 r == SSH_ERR_STRING_TOO_LARGE) { 868 error_fr(r, "parse"); 869 return -1; 870 } 871 fatal_fr(r, "parse"); 872 } 873 874 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 875 876 /* check whether agent is locked */ 877 if (locked && type != SSH_AGENTC_UNLOCK) { 878 sshbuf_reset(e->request); 879 switch (type) { 880 case SSH2_AGENTC_REQUEST_IDENTITIES: 881 /* send empty lists */ 882 no_identities(e); 883 break; 884 default: 885 /* send a fail message for all other request types */ 886 send_status(e, 0); 887 } 888 return 1; 889 } 890 891 switch (type) { 892 case SSH_AGENTC_LOCK: 893 case SSH_AGENTC_UNLOCK: 894 process_lock_agent(e, type == SSH_AGENTC_LOCK); 895 break; 896 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 897 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 898 break; 899 /* ssh2 */ 900 case SSH2_AGENTC_SIGN_REQUEST: 901 process_sign_request2(e); 902 break; 903 case SSH2_AGENTC_REQUEST_IDENTITIES: 904 process_request_identities(e); 905 break; 906 case SSH2_AGENTC_ADD_IDENTITY: 907 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 908 process_add_identity(e); 909 break; 910 case SSH2_AGENTC_REMOVE_IDENTITY: 911 process_remove_identity(e); 912 break; 913 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 914 process_remove_all_identities(e); 915 break; 916 #ifdef ENABLE_PKCS11 917 case SSH_AGENTC_ADD_SMARTCARD_KEY: 918 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 919 process_add_smartcard_key(e); 920 break; 921 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 922 process_remove_smartcard_key(e); 923 break; 924 #endif /* ENABLE_PKCS11 */ 925 default: 926 /* Unknown message. Respond with failure. */ 927 error("Unknown message %d", type); 928 sshbuf_reset(e->request); 929 send_status(e, 0); 930 break; 931 } 932 return 1; 933 } 934 935 static void 936 new_socket(sock_type type, int fd) 937 { 938 u_int i, old_alloc, new_alloc; 939 940 set_nonblock(fd); 941 942 if (fd > max_fd) 943 max_fd = fd; 944 945 for (i = 0; i < sockets_alloc; i++) 946 if (sockets[i].type == AUTH_UNUSED) { 947 sockets[i].fd = fd; 948 if ((sockets[i].input = sshbuf_new()) == NULL || 949 (sockets[i].output = sshbuf_new()) == NULL || 950 (sockets[i].request = sshbuf_new()) == NULL) 951 fatal_f("sshbuf_new failed"); 952 sockets[i].type = type; 953 return; 954 } 955 old_alloc = sockets_alloc; 956 new_alloc = sockets_alloc + 10; 957 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 958 for (i = old_alloc; i < new_alloc; i++) 959 sockets[i].type = AUTH_UNUSED; 960 sockets_alloc = new_alloc; 961 sockets[old_alloc].fd = fd; 962 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 963 (sockets[old_alloc].output = sshbuf_new()) == NULL || 964 (sockets[old_alloc].request = sshbuf_new()) == NULL) 965 fatal_f("sshbuf_new failed"); 966 sockets[old_alloc].type = type; 967 } 968 969 static int 970 handle_socket_read(u_int socknum) 971 { 972 struct sockaddr_un sunaddr; 973 socklen_t slen; 974 uid_t euid; 975 gid_t egid; 976 int fd; 977 978 slen = sizeof(sunaddr); 979 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 980 if (fd == -1) { 981 error("accept from AUTH_SOCKET: %s", strerror(errno)); 982 return -1; 983 } 984 if (getpeereid(fd, &euid, &egid) == -1) { 985 error("getpeereid %d failed: %s", fd, strerror(errno)); 986 close(fd); 987 return -1; 988 } 989 if ((euid != 0) && (getuid() != euid)) { 990 error("uid mismatch: peer euid %u != uid %u", 991 (u_int) euid, (u_int) getuid()); 992 close(fd); 993 return -1; 994 } 995 new_socket(AUTH_CONNECTION, fd); 996 return 0; 997 } 998 999 static int 1000 handle_conn_read(u_int socknum) 1001 { 1002 char buf[AGENT_RBUF_LEN]; 1003 ssize_t len; 1004 int r; 1005 1006 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1007 if (len == -1) { 1008 if (errno == EAGAIN || errno == EINTR) 1009 return 0; 1010 error_f("read error on socket %u (fd %d): %s", 1011 socknum, sockets[socknum].fd, strerror(errno)); 1012 } 1013 return -1; 1014 } 1015 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1016 fatal_fr(r, "compose"); 1017 explicit_bzero(buf, sizeof(buf)); 1018 for (;;) { 1019 if ((r = process_message(socknum)) == -1) 1020 return -1; 1021 else if (r == 0) 1022 break; 1023 } 1024 return 0; 1025 } 1026 1027 static int 1028 handle_conn_write(u_int socknum) 1029 { 1030 ssize_t len; 1031 int r; 1032 1033 if (sshbuf_len(sockets[socknum].output) == 0) 1034 return 0; /* shouldn't happen */ 1035 if ((len = write(sockets[socknum].fd, 1036 sshbuf_ptr(sockets[socknum].output), 1037 sshbuf_len(sockets[socknum].output))) <= 0) { 1038 if (len == -1) { 1039 if (errno == EAGAIN || errno == EINTR) 1040 return 0; 1041 error_f("read error on socket %u (fd %d): %s", 1042 socknum, sockets[socknum].fd, strerror(errno)); 1043 } 1044 return -1; 1045 } 1046 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1047 fatal_fr(r, "consume"); 1048 return 0; 1049 } 1050 1051 static void 1052 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1053 { 1054 size_t i; 1055 u_int socknum, activefds = npfd; 1056 1057 for (i = 0; i < npfd; i++) { 1058 if (pfd[i].revents == 0) 1059 continue; 1060 /* Find sockets entry */ 1061 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1062 if (sockets[socknum].type != AUTH_SOCKET && 1063 sockets[socknum].type != AUTH_CONNECTION) 1064 continue; 1065 if (pfd[i].fd == sockets[socknum].fd) 1066 break; 1067 } 1068 if (socknum >= sockets_alloc) { 1069 error_f("no socket for fd %d", pfd[i].fd); 1070 continue; 1071 } 1072 /* Process events */ 1073 switch (sockets[socknum].type) { 1074 case AUTH_SOCKET: 1075 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1076 break; 1077 if (npfd > maxfds) { 1078 debug3("out of fds (active %u >= limit %u); " 1079 "skipping accept", activefds, maxfds); 1080 break; 1081 } 1082 if (handle_socket_read(socknum) == 0) 1083 activefds++; 1084 break; 1085 case AUTH_CONNECTION: 1086 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1087 handle_conn_read(socknum) != 0) { 1088 goto close_sock; 1089 } 1090 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1091 handle_conn_write(socknum) != 0) { 1092 close_sock: 1093 if (activefds == 0) 1094 fatal("activefds == 0 at close_sock"); 1095 close_socket(&sockets[socknum]); 1096 activefds--; 1097 break; 1098 } 1099 break; 1100 default: 1101 break; 1102 } 1103 } 1104 } 1105 1106 static int 1107 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1108 { 1109 struct pollfd *pfd = *pfdp; 1110 size_t i, j, npfd = 0; 1111 time_t deadline; 1112 int r; 1113 1114 /* Count active sockets */ 1115 for (i = 0; i < sockets_alloc; i++) { 1116 switch (sockets[i].type) { 1117 case AUTH_SOCKET: 1118 case AUTH_CONNECTION: 1119 npfd++; 1120 break; 1121 case AUTH_UNUSED: 1122 break; 1123 default: 1124 fatal("Unknown socket type %d", sockets[i].type); 1125 break; 1126 } 1127 } 1128 if (npfd != *npfdp && 1129 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1130 fatal_f("recallocarray failed"); 1131 *pfdp = pfd; 1132 *npfdp = npfd; 1133 1134 for (i = j = 0; i < sockets_alloc; i++) { 1135 switch (sockets[i].type) { 1136 case AUTH_SOCKET: 1137 if (npfd > maxfds) { 1138 debug3("out of fds (active %zu >= limit %u); " 1139 "skipping arming listener", npfd, maxfds); 1140 break; 1141 } 1142 pfd[j].fd = sockets[i].fd; 1143 pfd[j].revents = 0; 1144 pfd[j].events = POLLIN; 1145 j++; 1146 break; 1147 case AUTH_CONNECTION: 1148 pfd[j].fd = sockets[i].fd; 1149 pfd[j].revents = 0; 1150 /* 1151 * Only prepare to read if we can handle a full-size 1152 * input read buffer and enqueue a max size reply.. 1153 */ 1154 if ((r = sshbuf_check_reserve(sockets[i].input, 1155 AGENT_RBUF_LEN)) == 0 && 1156 (r = sshbuf_check_reserve(sockets[i].output, 1157 AGENT_MAX_LEN)) == 0) 1158 pfd[j].events = POLLIN; 1159 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1160 fatal_fr(r, "reserve"); 1161 if (sshbuf_len(sockets[i].output) > 0) 1162 pfd[j].events |= POLLOUT; 1163 j++; 1164 break; 1165 default: 1166 break; 1167 } 1168 } 1169 deadline = reaper(); 1170 if (parent_alive_interval != 0) 1171 deadline = (deadline == 0) ? parent_alive_interval : 1172 MINIMUM(deadline, parent_alive_interval); 1173 if (deadline == 0) { 1174 *timeoutp = -1; /* INFTIM */ 1175 } else { 1176 if (deadline > INT_MAX / 1000) 1177 *timeoutp = INT_MAX / 1000; 1178 else 1179 *timeoutp = deadline * 1000; 1180 } 1181 return (1); 1182 } 1183 1184 static void 1185 cleanup_socket(void) 1186 { 1187 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1188 return; 1189 debug_f("cleanup"); 1190 if (socket_name[0]) 1191 unlink(socket_name); 1192 if (socket_dir[0]) 1193 rmdir(socket_dir); 1194 } 1195 1196 void 1197 cleanup_exit(int i) 1198 { 1199 cleanup_socket(); 1200 _exit(i); 1201 } 1202 1203 /*ARGSUSED*/ 1204 static void 1205 cleanup_handler(int sig) 1206 { 1207 cleanup_socket(); 1208 #ifdef ENABLE_PKCS11 1209 pkcs11_terminate(); 1210 #endif 1211 _exit(2); 1212 } 1213 1214 static void 1215 check_parent_exists(void) 1216 { 1217 /* 1218 * If our parent has exited then getppid() will return (pid_t)1, 1219 * so testing for that should be safe. 1220 */ 1221 if (parent_pid != -1 && getppid() != parent_pid) { 1222 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1223 cleanup_socket(); 1224 _exit(2); 1225 } 1226 } 1227 1228 static void 1229 usage(void) 1230 { 1231 fprintf(stderr, 1232 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1233 " [-P allowed_providers] [-t life]\n" 1234 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1235 " [-t life] command [arg ...]\n" 1236 " ssh-agent [-c | -s] -k\n"); 1237 exit(1); 1238 } 1239 1240 int 1241 main(int ac, char **av) 1242 { 1243 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1244 int sock, ch, result, saved_errno; 1245 char *shell, *format, *pidstr, *agentsocket = NULL; 1246 struct rlimit rlim; 1247 extern int optind; 1248 extern char *optarg; 1249 pid_t pid; 1250 char pidstrbuf[1 + 3 * sizeof pid]; 1251 size_t len; 1252 mode_t prev_mask; 1253 int timeout = -1; /* INFTIM */ 1254 struct pollfd *pfd = NULL; 1255 size_t npfd = 0; 1256 u_int maxfds; 1257 1258 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1259 sanitise_stdfd(); 1260 1261 /* drop */ 1262 setegid(getgid()); 1263 setgid(getgid()); 1264 1265 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1266 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1267 1268 #ifdef WITH_OPENSSL 1269 OpenSSL_add_all_algorithms(); 1270 #endif 1271 1272 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1273 switch (ch) { 1274 case 'E': 1275 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1276 if (fingerprint_hash == -1) 1277 fatal("Invalid hash algorithm \"%s\"", optarg); 1278 break; 1279 case 'c': 1280 if (s_flag) 1281 usage(); 1282 c_flag++; 1283 break; 1284 case 'k': 1285 k_flag++; 1286 break; 1287 case 'O': 1288 if (strcmp(optarg, "no-restrict-websafe") == 0) 1289 restrict_websafe = 0; 1290 else 1291 fatal("Unknown -O option"); 1292 break; 1293 case 'P': 1294 if (allowed_providers != NULL) 1295 fatal("-P option already specified"); 1296 allowed_providers = xstrdup(optarg); 1297 break; 1298 case 's': 1299 if (c_flag) 1300 usage(); 1301 s_flag++; 1302 break; 1303 case 'd': 1304 if (d_flag || D_flag) 1305 usage(); 1306 d_flag++; 1307 break; 1308 case 'D': 1309 if (d_flag || D_flag) 1310 usage(); 1311 D_flag++; 1312 break; 1313 case 'a': 1314 agentsocket = optarg; 1315 break; 1316 case 't': 1317 if ((lifetime = convtime(optarg)) == -1) { 1318 fprintf(stderr, "Invalid lifetime\n"); 1319 usage(); 1320 } 1321 break; 1322 default: 1323 usage(); 1324 } 1325 } 1326 ac -= optind; 1327 av += optind; 1328 1329 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1330 usage(); 1331 1332 if (allowed_providers == NULL) 1333 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1334 1335 if (ac == 0 && !c_flag && !s_flag) { 1336 shell = getenv("SHELL"); 1337 if (shell != NULL && (len = strlen(shell)) > 2 && 1338 strncmp(shell + len - 3, "csh", 3) == 0) 1339 c_flag = 1; 1340 } 1341 if (k_flag) { 1342 const char *errstr = NULL; 1343 1344 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1345 if (pidstr == NULL) { 1346 fprintf(stderr, "%s not set, cannot kill agent\n", 1347 SSH_AGENTPID_ENV_NAME); 1348 exit(1); 1349 } 1350 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1351 if (errstr) { 1352 fprintf(stderr, 1353 "%s=\"%s\", which is not a good PID: %s\n", 1354 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1355 exit(1); 1356 } 1357 if (kill(pid, SIGTERM) == -1) { 1358 perror("kill"); 1359 exit(1); 1360 } 1361 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1362 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1363 printf(format, SSH_AGENTPID_ENV_NAME); 1364 printf("echo Agent pid %ld killed;\n", (long)pid); 1365 exit(0); 1366 } 1367 1368 /* 1369 * Minimum file descriptors: 1370 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1371 * a few spare for libc / stack protectors / sanitisers, etc. 1372 */ 1373 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1374 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1375 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1376 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1377 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1378 1379 parent_pid = getpid(); 1380 1381 if (agentsocket == NULL) { 1382 /* Create private directory for agent socket */ 1383 mktemp_proto(socket_dir, sizeof(socket_dir)); 1384 if (mkdtemp(socket_dir) == NULL) { 1385 perror("mkdtemp: private socket dir"); 1386 exit(1); 1387 } 1388 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1389 (long)parent_pid); 1390 } else { 1391 /* Try to use specified agent socket */ 1392 socket_dir[0] = '\0'; 1393 strlcpy(socket_name, agentsocket, sizeof socket_name); 1394 } 1395 1396 /* 1397 * Create socket early so it will exist before command gets run from 1398 * the parent. 1399 */ 1400 prev_mask = umask(0177); 1401 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1402 if (sock < 0) { 1403 /* XXX - unix_listener() calls error() not perror() */ 1404 *socket_name = '\0'; /* Don't unlink any existing file */ 1405 cleanup_exit(1); 1406 } 1407 umask(prev_mask); 1408 1409 /* 1410 * Fork, and have the parent execute the command, if any, or present 1411 * the socket data. The child continues as the authentication agent. 1412 */ 1413 if (D_flag || d_flag) { 1414 log_init(__progname, 1415 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1416 SYSLOG_FACILITY_AUTH, 1); 1417 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1418 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1419 SSH_AUTHSOCKET_ENV_NAME); 1420 printf("echo Agent pid %ld;\n", (long)parent_pid); 1421 fflush(stdout); 1422 goto skip; 1423 } 1424 pid = fork(); 1425 if (pid == -1) { 1426 perror("fork"); 1427 cleanup_exit(1); 1428 } 1429 if (pid != 0) { /* Parent - execute the given command. */ 1430 close(sock); 1431 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1432 if (ac == 0) { 1433 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1434 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1435 SSH_AUTHSOCKET_ENV_NAME); 1436 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1437 SSH_AGENTPID_ENV_NAME); 1438 printf("echo Agent pid %ld;\n", (long)pid); 1439 exit(0); 1440 } 1441 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1442 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1443 perror("setenv"); 1444 exit(1); 1445 } 1446 execvp(av[0], av); 1447 perror(av[0]); 1448 exit(1); 1449 } 1450 /* child */ 1451 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1452 1453 if (setsid() == -1) { 1454 error("setsid: %s", strerror(errno)); 1455 cleanup_exit(1); 1456 } 1457 1458 (void)chdir("/"); 1459 if (stdfd_devnull(1, 1, 1) == -1) 1460 error_f("stdfd_devnull failed"); 1461 1462 /* deny core dumps, since memory contains unencrypted private keys */ 1463 rlim.rlim_cur = rlim.rlim_max = 0; 1464 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1465 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1466 cleanup_exit(1); 1467 } 1468 1469 skip: 1470 1471 cleanup_pid = getpid(); 1472 1473 #ifdef ENABLE_PKCS11 1474 pkcs11_init(0); 1475 #endif 1476 new_socket(AUTH_SOCKET, sock); 1477 if (ac > 0) 1478 parent_alive_interval = 10; 1479 idtab_init(); 1480 ssh_signal(SIGPIPE, SIG_IGN); 1481 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1482 ssh_signal(SIGHUP, cleanup_handler); 1483 ssh_signal(SIGTERM, cleanup_handler); 1484 1485 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1486 fatal("%s: pledge: %s", __progname, strerror(errno)); 1487 1488 while (1) { 1489 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1490 result = poll(pfd, npfd, timeout); 1491 saved_errno = errno; 1492 if (parent_alive_interval != 0) 1493 check_parent_exists(); 1494 (void) reaper(); /* remove expired keys */ 1495 if (result == -1) { 1496 if (saved_errno == EINTR) 1497 continue; 1498 fatal("poll: %s", strerror(saved_errno)); 1499 } else if (result > 0) 1500 after_poll(pfd, npfd, maxfds); 1501 } 1502 /* NOTREACHED */ 1503 } 1504