1 /* $OpenBSD: ssh-agent.c,v 1.262 2020/07/05 23:59:45 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("%s: buffer error: %s", __func__, ssh_err(r)); 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("%s: sshbuf_new failed", __func__); 240 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 241 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 242 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 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("%s: put key/comment: %s", __func__, 248 ssh_err(r)); 249 continue; 250 } 251 } 252 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 253 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 254 sshbuf_free(msg); 255 } 256 257 258 static char * 259 agent_decode_alg(struct sshkey *key, u_int flags) 260 { 261 if (key->type == KEY_RSA) { 262 if (flags & SSH_AGENT_RSA_SHA2_256) 263 return "rsa-sha2-256"; 264 else if (flags & SSH_AGENT_RSA_SHA2_512) 265 return "rsa-sha2-512"; 266 } else if (key->type == KEY_RSA_CERT) { 267 if (flags & SSH_AGENT_RSA_SHA2_256) 268 return "rsa-sha2-256-cert-v01@openssh.com"; 269 else if (flags & SSH_AGENT_RSA_SHA2_512) 270 return "rsa-sha2-512-cert-v01@openssh.com"; 271 } 272 return NULL; 273 } 274 275 /* 276 * This function inspects a message to be signed by a FIDO key that has a 277 * web-like application string (i.e. one that does not begin with "ssh:". 278 * It checks that the message is one of those expected for SSH operations 279 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 280 * for the web. 281 */ 282 static int 283 check_websafe_message_contents(struct sshkey *key, 284 const u_char *msg, size_t len) 285 { 286 int matched = 0; 287 struct sshbuf *b; 288 u_char m, n; 289 char *cp1 = NULL, *cp2 = NULL; 290 int r; 291 struct sshkey *mkey = NULL; 292 293 if ((b = sshbuf_from(msg, len)) == NULL) 294 fatal("%s: sshbuf_new", __func__); 295 296 /* SSH userauth request */ 297 if ((r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* sess_id */ 298 (r = sshbuf_get_u8(b, &m)) == 0 && /* SSH2_MSG_USERAUTH_REQUEST */ 299 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* server user */ 300 (r = sshbuf_get_cstring(b, &cp1, NULL)) == 0 && /* service */ 301 (r = sshbuf_get_cstring(b, &cp2, NULL)) == 0 && /* method */ 302 (r = sshbuf_get_u8(b, &n)) == 0 && /* sig-follows */ 303 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* alg */ 304 (r = sshkey_froms(b, &mkey)) == 0 && /* key */ 305 sshbuf_len(b) == 0) { 306 debug("%s: parsed userauth", __func__); 307 if (m == SSH2_MSG_USERAUTH_REQUEST && n == 1 && 308 strcmp(cp1, "ssh-connection") == 0 && 309 strcmp(cp2, "publickey") == 0 && 310 sshkey_equal(key, mkey)) { 311 debug("%s: well formed userauth", __func__); 312 matched = 1; 313 } 314 } 315 free(cp1); 316 free(cp2); 317 sshkey_free(mkey); 318 sshbuf_free(b); 319 if (matched) 320 return 1; 321 322 if ((b = sshbuf_from(msg, len)) == NULL) 323 fatal("%s: sshbuf_new", __func__); 324 cp1 = cp2 = NULL; 325 mkey = NULL; 326 327 /* SSHSIG */ 328 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) == 0 && 329 (r = sshbuf_consume(b, 6)) == 0 && 330 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* namespace */ 331 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* reserved */ 332 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* hashalg */ 333 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* H(msg) */ 334 sshbuf_len(b) == 0) { 335 debug("%s: parsed sshsig", __func__); 336 matched = 1; 337 } 338 339 sshbuf_free(b); 340 if (matched) 341 return 1; 342 343 /* XXX CA signature operation */ 344 345 error("web-origin key attempting to sign non-SSH message"); 346 return 0; 347 } 348 349 /* ssh2 only */ 350 static void 351 process_sign_request2(SocketEntry *e) 352 { 353 const u_char *data; 354 u_char *signature = NULL; 355 size_t dlen, slen = 0; 356 u_int compat = 0, flags; 357 int r, ok = -1; 358 char *fp = NULL; 359 struct sshbuf *msg; 360 struct sshkey *key = NULL; 361 struct identity *id; 362 struct notifier_ctx *notifier = NULL; 363 364 if ((msg = sshbuf_new()) == NULL) 365 fatal("%s: sshbuf_new failed", __func__); 366 if ((r = sshkey_froms(e->request, &key)) != 0 || 367 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 368 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 369 error("%s: couldn't parse request: %s", __func__, ssh_err(r)); 370 goto send; 371 } 372 373 if ((id = lookup_identity(key)) == NULL) { 374 verbose("%s: %s key not found", __func__, sshkey_type(key)); 375 goto send; 376 } 377 if (id->confirm && confirm_key(id) != 0) { 378 verbose("%s: user refused key", __func__); 379 goto send; 380 } 381 if (sshkey_is_sk(id->key)) { 382 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 383 !check_websafe_message_contents(key, data, dlen)) { 384 /* error already logged */ 385 goto send; 386 } 387 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 388 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 389 SSH_FP_DEFAULT)) == NULL) 390 fatal("%s: fingerprint failed", __func__); 391 notifier = notify_start(0, 392 "Confirm user presence for key %s %s", 393 sshkey_type(id->key), fp); 394 } 395 } 396 if ((r = sshkey_sign(id->key, &signature, &slen, 397 data, dlen, agent_decode_alg(key, flags), 398 id->sk_provider, compat)) != 0) { 399 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 400 goto send; 401 } 402 /* Success */ 403 ok = 0; 404 send: 405 notify_complete(notifier); 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("%s: buffer error: %s", __func__, ssh_err(r)); 412 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 413 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 414 415 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 416 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 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("%s: get key: %s", __func__, ssh_err(r)); 432 goto done; 433 } 434 if ((id = lookup_identity(key)) == NULL) { 435 debug("%s: key not found", __func__); 436 goto done; 437 } 438 /* We have this key, free it. */ 439 if (idtab->nentries < 1) 440 fatal("%s: internal error: nentries %d", 441 __func__, idtab->nentries); 442 TAILQ_REMOVE(&idtab->idlist, id, next); 443 free_identity(id); 444 idtab->nentries--; 445 sshkey_free(key); 446 success = 1; 447 done: 448 send_status(e, success); 449 } 450 451 static void 452 process_remove_all_identities(SocketEntry *e) 453 { 454 Identity *id; 455 456 /* Loop over all identities and clear the keys. */ 457 for (id = TAILQ_FIRST(&idtab->idlist); id; 458 id = TAILQ_FIRST(&idtab->idlist)) { 459 TAILQ_REMOVE(&idtab->idlist, id, next); 460 free_identity(id); 461 } 462 463 /* Mark that there are no identities. */ 464 idtab->nentries = 0; 465 466 /* Send success. */ 467 send_status(e, 1); 468 } 469 470 /* removes expired keys and returns number of seconds until the next expiry */ 471 static time_t 472 reaper(void) 473 { 474 time_t deadline = 0, now = monotime(); 475 Identity *id, *nxt; 476 477 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 478 nxt = TAILQ_NEXT(id, next); 479 if (id->death == 0) 480 continue; 481 if (now >= id->death) { 482 debug("expiring key '%s'", id->comment); 483 TAILQ_REMOVE(&idtab->idlist, id, next); 484 free_identity(id); 485 idtab->nentries--; 486 } else 487 deadline = (deadline == 0) ? id->death : 488 MINIMUM(deadline, id->death); 489 } 490 if (deadline == 0 || deadline <= now) 491 return 0; 492 else 493 return (deadline - now); 494 } 495 496 static void 497 process_add_identity(SocketEntry *e) 498 { 499 Identity *id; 500 int success = 0, confirm = 0; 501 u_int seconds = 0, maxsign; 502 char *fp, *comment = NULL, *ext_name = NULL, *sk_provider = NULL; 503 char canonical_provider[PATH_MAX]; 504 time_t death = 0; 505 struct sshkey *k = NULL; 506 u_char ctype; 507 int r = SSH_ERR_INTERNAL_ERROR; 508 509 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 510 k == NULL || 511 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 512 error("%s: decode private key: %s", __func__, ssh_err(r)); 513 goto err; 514 } 515 while (sshbuf_len(e->request)) { 516 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 517 error("%s: buffer error: %s", __func__, ssh_err(r)); 518 goto err; 519 } 520 switch (ctype) { 521 case SSH_AGENT_CONSTRAIN_LIFETIME: 522 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 523 error("%s: bad lifetime constraint: %s", 524 __func__, ssh_err(r)); 525 goto err; 526 } 527 death = monotime() + seconds; 528 break; 529 case SSH_AGENT_CONSTRAIN_CONFIRM: 530 confirm = 1; 531 break; 532 case SSH_AGENT_CONSTRAIN_MAXSIGN: 533 if ((r = sshbuf_get_u32(e->request, &maxsign)) != 0) { 534 error("%s: bad maxsign constraint: %s", 535 __func__, ssh_err(r)); 536 goto err; 537 } 538 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 539 error("%s: cannot enable maxsign: %s", 540 __func__, ssh_err(r)); 541 goto err; 542 } 543 break; 544 case SSH_AGENT_CONSTRAIN_EXTENSION: 545 if ((r = sshbuf_get_cstring(e->request, 546 &ext_name, NULL)) != 0) { 547 error("%s: cannot parse extension: %s", 548 __func__, ssh_err(r)); 549 goto err; 550 } 551 debug("%s: constraint ext %s", __func__, ext_name); 552 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 553 if (sk_provider != NULL) { 554 error("%s already set", ext_name); 555 goto err; 556 } 557 if ((r = sshbuf_get_cstring(e->request, 558 &sk_provider, NULL)) != 0) { 559 error("%s: cannot parse %s: %s", 560 __func__, ext_name, ssh_err(r)); 561 goto err; 562 } 563 } else { 564 error("%s: unsupported constraint \"%s\"", 565 __func__, ext_name); 566 goto err; 567 } 568 free(ext_name); 569 break; 570 default: 571 error("%s: Unknown constraint %d", __func__, ctype); 572 err: 573 free(sk_provider); 574 free(ext_name); 575 sshbuf_reset(e->request); 576 free(comment); 577 sshkey_free(k); 578 goto send; 579 } 580 } 581 if (sk_provider != NULL) { 582 if (!sshkey_is_sk(k)) { 583 error("Cannot add provider: %s is not an " 584 "authenticator-hosted key", sshkey_type(k)); 585 free(sk_provider); 586 goto send; 587 } 588 if (strcasecmp(sk_provider, "internal") == 0) { 589 debug("%s: internal provider", __func__); 590 } else { 591 if (realpath(sk_provider, canonical_provider) == NULL) { 592 verbose("failed provider \"%.100s\": " 593 "realpath: %s", sk_provider, 594 strerror(errno)); 595 free(sk_provider); 596 goto send; 597 } 598 free(sk_provider); 599 sk_provider = xstrdup(canonical_provider); 600 if (match_pattern_list(sk_provider, 601 allowed_providers, 0) != 1) { 602 error("Refusing add key: " 603 "provider %s not allowed", sk_provider); 604 free(sk_provider); 605 goto send; 606 } 607 } 608 } 609 if ((r = sshkey_shield_private(k)) != 0) { 610 error("%s: shield private key: %s", __func__, ssh_err(r)); 611 goto err; 612 } 613 614 success = 1; 615 if (lifetime && !death) 616 death = monotime() + lifetime; 617 if ((id = lookup_identity(k)) == NULL) { 618 id = xcalloc(1, sizeof(Identity)); 619 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 620 /* Increment the number of identities. */ 621 idtab->nentries++; 622 } else { 623 /* key state might have been updated */ 624 sshkey_free(id->key); 625 free(id->comment); 626 free(id->sk_provider); 627 } 628 id->key = k; 629 id->comment = comment; 630 id->death = death; 631 id->confirm = confirm; 632 id->sk_provider = sk_provider; 633 634 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 635 SSH_FP_DEFAULT)) == NULL) 636 fatal("%s: sshkey_fingerprint failed", __func__); 637 debug("%s: add %s %s \"%.100s\" (life: %u) (confirm: %u) " 638 "(provider: %s)", __func__, sshkey_ssh_name(k), fp, comment, 639 seconds, confirm, sk_provider == NULL ? "none" : sk_provider); 640 free(fp); 641 send: 642 send_status(e, success); 643 } 644 645 /* XXX todo: encrypt sensitive data with passphrase */ 646 static void 647 process_lock_agent(SocketEntry *e, int lock) 648 { 649 int r, success = 0, delay; 650 char *passwd; 651 u_char passwdhash[LOCK_SIZE]; 652 static u_int fail_count = 0; 653 size_t pwlen; 654 655 /* 656 * This is deliberately fatal: the user has requested that we lock, 657 * but we can't parse their request properly. The only safe thing to 658 * do is abort. 659 */ 660 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 661 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 662 if (pwlen == 0) { 663 debug("empty password not supported"); 664 } else if (locked && !lock) { 665 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 666 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 667 fatal("bcrypt_pbkdf"); 668 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 669 debug("agent unlocked"); 670 locked = 0; 671 fail_count = 0; 672 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 673 success = 1; 674 } else { 675 /* delay in 0.1s increments up to 10s */ 676 if (fail_count < 100) 677 fail_count++; 678 delay = 100000 * fail_count; 679 debug("unlock failed, delaying %0.1lf seconds", 680 (double)delay/1000000); 681 usleep(delay); 682 } 683 explicit_bzero(passwdhash, sizeof(passwdhash)); 684 } else if (!locked && lock) { 685 debug("agent locked"); 686 locked = 1; 687 arc4random_buf(lock_salt, sizeof(lock_salt)); 688 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 689 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 690 fatal("bcrypt_pbkdf"); 691 success = 1; 692 } 693 freezero(passwd, pwlen); 694 send_status(e, success); 695 } 696 697 static void 698 no_identities(SocketEntry *e) 699 { 700 struct sshbuf *msg; 701 int r; 702 703 if ((msg = sshbuf_new()) == NULL) 704 fatal("%s: sshbuf_new failed", __func__); 705 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 706 (r = sshbuf_put_u32(msg, 0)) != 0 || 707 (r = sshbuf_put_stringb(e->output, msg)) != 0) 708 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 709 sshbuf_free(msg); 710 } 711 712 #ifdef ENABLE_PKCS11 713 static void 714 process_add_smartcard_key(SocketEntry *e) 715 { 716 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 717 char **comments = NULL; 718 int r, i, count = 0, success = 0, confirm = 0; 719 u_int seconds; 720 time_t death = 0; 721 u_char type; 722 struct sshkey **keys = NULL, *k; 723 Identity *id; 724 725 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 726 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 727 error("%s: buffer error: %s", __func__, ssh_err(r)); 728 goto send; 729 } 730 731 while (sshbuf_len(e->request)) { 732 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 733 error("%s: buffer error: %s", __func__, ssh_err(r)); 734 goto send; 735 } 736 switch (type) { 737 case SSH_AGENT_CONSTRAIN_LIFETIME: 738 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 739 error("%s: buffer error: %s", 740 __func__, ssh_err(r)); 741 goto send; 742 } 743 death = monotime() + seconds; 744 break; 745 case SSH_AGENT_CONSTRAIN_CONFIRM: 746 confirm = 1; 747 break; 748 default: 749 error("%s: Unknown constraint type %d", __func__, type); 750 goto send; 751 } 752 } 753 if (realpath(provider, canonical_provider) == NULL) { 754 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 755 provider, strerror(errno)); 756 goto send; 757 } 758 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 759 verbose("refusing PKCS#11 add of \"%.100s\": " 760 "provider not allowed", canonical_provider); 761 goto send; 762 } 763 debug("%s: add %.100s", __func__, canonical_provider); 764 if (lifetime && !death) 765 death = monotime() + lifetime; 766 767 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 768 for (i = 0; i < count; i++) { 769 k = keys[i]; 770 if (lookup_identity(k) == NULL) { 771 id = xcalloc(1, sizeof(Identity)); 772 id->key = k; 773 keys[i] = NULL; /* transferred */ 774 id->provider = xstrdup(canonical_provider); 775 if (*comments[i] != '\0') { 776 id->comment = comments[i]; 777 comments[i] = NULL; /* transferred */ 778 } else { 779 id->comment = xstrdup(canonical_provider); 780 } 781 id->death = death; 782 id->confirm = confirm; 783 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 784 idtab->nentries++; 785 success = 1; 786 } 787 sshkey_free(keys[i]); 788 free(comments[i]); 789 } 790 send: 791 free(pin); 792 free(provider); 793 free(keys); 794 free(comments); 795 send_status(e, success); 796 } 797 798 static void 799 process_remove_smartcard_key(SocketEntry *e) 800 { 801 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 802 int r, success = 0; 803 Identity *id, *nxt; 804 805 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 806 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 807 error("%s: buffer error: %s", __func__, ssh_err(r)); 808 goto send; 809 } 810 free(pin); 811 812 if (realpath(provider, canonical_provider) == NULL) { 813 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 814 provider, strerror(errno)); 815 goto send; 816 } 817 818 debug("%s: remove %.100s", __func__, canonical_provider); 819 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 820 nxt = TAILQ_NEXT(id, next); 821 /* Skip file--based keys */ 822 if (id->provider == NULL) 823 continue; 824 if (!strcmp(canonical_provider, id->provider)) { 825 TAILQ_REMOVE(&idtab->idlist, id, next); 826 free_identity(id); 827 idtab->nentries--; 828 } 829 } 830 if (pkcs11_del_provider(canonical_provider) == 0) 831 success = 1; 832 else 833 error("%s: pkcs11_del_provider failed", __func__); 834 send: 835 free(provider); 836 send_status(e, success); 837 } 838 #endif /* ENABLE_PKCS11 */ 839 840 /* dispatch incoming messages */ 841 842 static int 843 process_message(u_int socknum) 844 { 845 u_int msg_len; 846 u_char type; 847 const u_char *cp; 848 int r; 849 SocketEntry *e; 850 851 if (socknum >= sockets_alloc) { 852 fatal("%s: socket number %u >= allocated %u", 853 __func__, socknum, sockets_alloc); 854 } 855 e = &sockets[socknum]; 856 857 if (sshbuf_len(e->input) < 5) 858 return 0; /* Incomplete message header. */ 859 cp = sshbuf_ptr(e->input); 860 msg_len = PEEK_U32(cp); 861 if (msg_len > AGENT_MAX_LEN) { 862 debug("%s: socket %u (fd=%d) message too long %u > %u", 863 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 864 return -1; 865 } 866 if (sshbuf_len(e->input) < msg_len + 4) 867 return 0; /* Incomplete message body. */ 868 869 /* move the current input to e->request */ 870 sshbuf_reset(e->request); 871 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 872 (r = sshbuf_get_u8(e->request, &type)) != 0) { 873 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 874 r == SSH_ERR_STRING_TOO_LARGE) { 875 debug("%s: buffer error: %s", __func__, ssh_err(r)); 876 return -1; 877 } 878 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 879 } 880 881 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 882 883 /* check whether agent is locked */ 884 if (locked && type != SSH_AGENTC_UNLOCK) { 885 sshbuf_reset(e->request); 886 switch (type) { 887 case SSH2_AGENTC_REQUEST_IDENTITIES: 888 /* send empty lists */ 889 no_identities(e); 890 break; 891 default: 892 /* send a fail message for all other request types */ 893 send_status(e, 0); 894 } 895 return 0; 896 } 897 898 switch (type) { 899 case SSH_AGENTC_LOCK: 900 case SSH_AGENTC_UNLOCK: 901 process_lock_agent(e, type == SSH_AGENTC_LOCK); 902 break; 903 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 904 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 905 break; 906 /* ssh2 */ 907 case SSH2_AGENTC_SIGN_REQUEST: 908 process_sign_request2(e); 909 break; 910 case SSH2_AGENTC_REQUEST_IDENTITIES: 911 process_request_identities(e); 912 break; 913 case SSH2_AGENTC_ADD_IDENTITY: 914 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 915 process_add_identity(e); 916 break; 917 case SSH2_AGENTC_REMOVE_IDENTITY: 918 process_remove_identity(e); 919 break; 920 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 921 process_remove_all_identities(e); 922 break; 923 #ifdef ENABLE_PKCS11 924 case SSH_AGENTC_ADD_SMARTCARD_KEY: 925 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 926 process_add_smartcard_key(e); 927 break; 928 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 929 process_remove_smartcard_key(e); 930 break; 931 #endif /* ENABLE_PKCS11 */ 932 default: 933 /* Unknown message. Respond with failure. */ 934 error("Unknown message %d", type); 935 sshbuf_reset(e->request); 936 send_status(e, 0); 937 break; 938 } 939 return 0; 940 } 941 942 static void 943 new_socket(sock_type type, int fd) 944 { 945 u_int i, old_alloc, new_alloc; 946 947 set_nonblock(fd); 948 949 if (fd > max_fd) 950 max_fd = fd; 951 952 for (i = 0; i < sockets_alloc; i++) 953 if (sockets[i].type == AUTH_UNUSED) { 954 sockets[i].fd = fd; 955 if ((sockets[i].input = sshbuf_new()) == NULL) 956 fatal("%s: sshbuf_new failed", __func__); 957 if ((sockets[i].output = sshbuf_new()) == NULL) 958 fatal("%s: sshbuf_new failed", __func__); 959 if ((sockets[i].request = sshbuf_new()) == NULL) 960 fatal("%s: sshbuf_new failed", __func__); 961 sockets[i].type = type; 962 return; 963 } 964 old_alloc = sockets_alloc; 965 new_alloc = sockets_alloc + 10; 966 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 967 for (i = old_alloc; i < new_alloc; i++) 968 sockets[i].type = AUTH_UNUSED; 969 sockets_alloc = new_alloc; 970 sockets[old_alloc].fd = fd; 971 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 972 fatal("%s: sshbuf_new failed", __func__); 973 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 974 fatal("%s: sshbuf_new failed", __func__); 975 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 976 fatal("%s: sshbuf_new failed", __func__); 977 sockets[old_alloc].type = type; 978 } 979 980 static int 981 handle_socket_read(u_int socknum) 982 { 983 struct sockaddr_un sunaddr; 984 socklen_t slen; 985 uid_t euid; 986 gid_t egid; 987 int fd; 988 989 slen = sizeof(sunaddr); 990 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 991 if (fd == -1) { 992 error("accept from AUTH_SOCKET: %s", strerror(errno)); 993 return -1; 994 } 995 if (getpeereid(fd, &euid, &egid) == -1) { 996 error("getpeereid %d failed: %s", fd, strerror(errno)); 997 close(fd); 998 return -1; 999 } 1000 if ((euid != 0) && (getuid() != euid)) { 1001 error("uid mismatch: peer euid %u != uid %u", 1002 (u_int) euid, (u_int) getuid()); 1003 close(fd); 1004 return -1; 1005 } 1006 new_socket(AUTH_CONNECTION, fd); 1007 return 0; 1008 } 1009 1010 static int 1011 handle_conn_read(u_int socknum) 1012 { 1013 char buf[AGENT_RBUF_LEN]; 1014 ssize_t len; 1015 int r; 1016 1017 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1018 if (len == -1) { 1019 if (errno == EAGAIN || errno == EINTR) 1020 return 0; 1021 error("%s: read error on socket %u (fd %d): %s", 1022 __func__, socknum, sockets[socknum].fd, 1023 strerror(errno)); 1024 } 1025 return -1; 1026 } 1027 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1028 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1029 explicit_bzero(buf, sizeof(buf)); 1030 process_message(socknum); 1031 return 0; 1032 } 1033 1034 static int 1035 handle_conn_write(u_int socknum) 1036 { 1037 ssize_t len; 1038 int r; 1039 1040 if (sshbuf_len(sockets[socknum].output) == 0) 1041 return 0; /* shouldn't happen */ 1042 if ((len = write(sockets[socknum].fd, 1043 sshbuf_ptr(sockets[socknum].output), 1044 sshbuf_len(sockets[socknum].output))) <= 0) { 1045 if (len == -1) { 1046 if (errno == EAGAIN || errno == EINTR) 1047 return 0; 1048 error("%s: read error on socket %u (fd %d): %s", 1049 __func__, socknum, sockets[socknum].fd, 1050 strerror(errno)); 1051 } 1052 return -1; 1053 } 1054 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1055 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1056 return 0; 1057 } 1058 1059 static void 1060 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1061 { 1062 size_t i; 1063 u_int socknum, activefds = npfd; 1064 1065 for (i = 0; i < npfd; i++) { 1066 if (pfd[i].revents == 0) 1067 continue; 1068 /* Find sockets entry */ 1069 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1070 if (sockets[socknum].type != AUTH_SOCKET && 1071 sockets[socknum].type != AUTH_CONNECTION) 1072 continue; 1073 if (pfd[i].fd == sockets[socknum].fd) 1074 break; 1075 } 1076 if (socknum >= sockets_alloc) { 1077 error("%s: no socket for fd %d", __func__, pfd[i].fd); 1078 continue; 1079 } 1080 /* Process events */ 1081 switch (sockets[socknum].type) { 1082 case AUTH_SOCKET: 1083 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1084 break; 1085 if (npfd > maxfds) { 1086 debug3("out of fds (active %u >= limit %u); " 1087 "skipping accept", activefds, maxfds); 1088 break; 1089 } 1090 if (handle_socket_read(socknum) == 0) 1091 activefds++; 1092 break; 1093 case AUTH_CONNECTION: 1094 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1095 handle_conn_read(socknum) != 0) { 1096 goto close_sock; 1097 } 1098 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1099 handle_conn_write(socknum) != 0) { 1100 close_sock: 1101 if (activefds == 0) 1102 fatal("activefds == 0 at close_sock"); 1103 close_socket(&sockets[socknum]); 1104 activefds--; 1105 break; 1106 } 1107 break; 1108 default: 1109 break; 1110 } 1111 } 1112 } 1113 1114 static int 1115 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1116 { 1117 struct pollfd *pfd = *pfdp; 1118 size_t i, j, npfd = 0; 1119 time_t deadline; 1120 int r; 1121 1122 /* Count active sockets */ 1123 for (i = 0; i < sockets_alloc; i++) { 1124 switch (sockets[i].type) { 1125 case AUTH_SOCKET: 1126 case AUTH_CONNECTION: 1127 npfd++; 1128 break; 1129 case AUTH_UNUSED: 1130 break; 1131 default: 1132 fatal("Unknown socket type %d", sockets[i].type); 1133 break; 1134 } 1135 } 1136 if (npfd != *npfdp && 1137 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1138 fatal("%s: recallocarray failed", __func__); 1139 *pfdp = pfd; 1140 *npfdp = npfd; 1141 1142 for (i = j = 0; i < sockets_alloc; i++) { 1143 switch (sockets[i].type) { 1144 case AUTH_SOCKET: 1145 if (npfd > maxfds) { 1146 debug3("out of fds (active %zu >= limit %u); " 1147 "skipping arming listener", npfd, maxfds); 1148 break; 1149 } 1150 pfd[j].fd = sockets[i].fd; 1151 pfd[j].revents = 0; 1152 pfd[j].events = POLLIN; 1153 j++; 1154 break; 1155 case AUTH_CONNECTION: 1156 pfd[j].fd = sockets[i].fd; 1157 pfd[j].revents = 0; 1158 /* 1159 * Only prepare to read if we can handle a full-size 1160 * input read buffer and enqueue a max size reply.. 1161 */ 1162 if ((r = sshbuf_check_reserve(sockets[i].input, 1163 AGENT_RBUF_LEN)) == 0 && 1164 (r = sshbuf_check_reserve(sockets[i].output, 1165 AGENT_MAX_LEN)) == 0) 1166 pfd[j].events = POLLIN; 1167 else if (r != SSH_ERR_NO_BUFFER_SPACE) { 1168 fatal("%s: buffer error: %s", 1169 __func__, ssh_err(r)); 1170 } 1171 if (sshbuf_len(sockets[i].output) > 0) 1172 pfd[j].events |= POLLOUT; 1173 j++; 1174 break; 1175 default: 1176 break; 1177 } 1178 } 1179 deadline = reaper(); 1180 if (parent_alive_interval != 0) 1181 deadline = (deadline == 0) ? parent_alive_interval : 1182 MINIMUM(deadline, parent_alive_interval); 1183 if (deadline == 0) { 1184 *timeoutp = -1; /* INFTIM */ 1185 } else { 1186 if (deadline > INT_MAX / 1000) 1187 *timeoutp = INT_MAX / 1000; 1188 else 1189 *timeoutp = deadline * 1000; 1190 } 1191 return (1); 1192 } 1193 1194 static void 1195 cleanup_socket(void) 1196 { 1197 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1198 return; 1199 debug("%s: cleanup", __func__); 1200 if (socket_name[0]) 1201 unlink(socket_name); 1202 if (socket_dir[0]) 1203 rmdir(socket_dir); 1204 } 1205 1206 void 1207 cleanup_exit(int i) 1208 { 1209 cleanup_socket(); 1210 _exit(i); 1211 } 1212 1213 /*ARGSUSED*/ 1214 static void 1215 cleanup_handler(int sig) 1216 { 1217 cleanup_socket(); 1218 #ifdef ENABLE_PKCS11 1219 pkcs11_terminate(); 1220 #endif 1221 _exit(2); 1222 } 1223 1224 static void 1225 check_parent_exists(void) 1226 { 1227 /* 1228 * If our parent has exited then getppid() will return (pid_t)1, 1229 * so testing for that should be safe. 1230 */ 1231 if (parent_pid != -1 && getppid() != parent_pid) { 1232 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1233 cleanup_socket(); 1234 _exit(2); 1235 } 1236 } 1237 1238 static void 1239 usage(void) 1240 { 1241 fprintf(stderr, 1242 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1243 " [-P allowed_providers] [-t life]\n" 1244 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1245 " [-t life] command [arg ...]\n" 1246 " ssh-agent [-c | -s] -k\n"); 1247 exit(1); 1248 } 1249 1250 int 1251 main(int ac, char **av) 1252 { 1253 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1254 int sock, fd, ch, result, saved_errno; 1255 char *shell, *format, *pidstr, *agentsocket = NULL; 1256 struct rlimit rlim; 1257 extern int optind; 1258 extern char *optarg; 1259 pid_t pid; 1260 char pidstrbuf[1 + 3 * sizeof pid]; 1261 size_t len; 1262 mode_t prev_mask; 1263 int timeout = -1; /* INFTIM */ 1264 struct pollfd *pfd = NULL; 1265 size_t npfd = 0; 1266 u_int maxfds; 1267 1268 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1269 sanitise_stdfd(); 1270 1271 /* drop */ 1272 setegid(getgid()); 1273 setgid(getgid()); 1274 1275 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1276 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1277 1278 #ifdef WITH_OPENSSL 1279 OpenSSL_add_all_algorithms(); 1280 #endif 1281 1282 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1283 switch (ch) { 1284 case 'E': 1285 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1286 if (fingerprint_hash == -1) 1287 fatal("Invalid hash algorithm \"%s\"", optarg); 1288 break; 1289 case 'c': 1290 if (s_flag) 1291 usage(); 1292 c_flag++; 1293 break; 1294 case 'k': 1295 k_flag++; 1296 break; 1297 case 'O': 1298 if (strcmp(optarg, "no-restrict-websafe") == 0) 1299 restrict_websafe = 0; 1300 else 1301 fatal("Unknown -O option"); 1302 break; 1303 case 'P': 1304 if (allowed_providers != NULL) 1305 fatal("-P option already specified"); 1306 allowed_providers = xstrdup(optarg); 1307 break; 1308 case 's': 1309 if (c_flag) 1310 usage(); 1311 s_flag++; 1312 break; 1313 case 'd': 1314 if (d_flag || D_flag) 1315 usage(); 1316 d_flag++; 1317 break; 1318 case 'D': 1319 if (d_flag || D_flag) 1320 usage(); 1321 D_flag++; 1322 break; 1323 case 'a': 1324 agentsocket = optarg; 1325 break; 1326 case 't': 1327 if ((lifetime = convtime(optarg)) == -1) { 1328 fprintf(stderr, "Invalid lifetime\n"); 1329 usage(); 1330 } 1331 break; 1332 default: 1333 usage(); 1334 } 1335 } 1336 ac -= optind; 1337 av += optind; 1338 1339 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1340 usage(); 1341 1342 if (allowed_providers == NULL) 1343 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1344 1345 if (ac == 0 && !c_flag && !s_flag) { 1346 shell = getenv("SHELL"); 1347 if (shell != NULL && (len = strlen(shell)) > 2 && 1348 strncmp(shell + len - 3, "csh", 3) == 0) 1349 c_flag = 1; 1350 } 1351 if (k_flag) { 1352 const char *errstr = NULL; 1353 1354 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1355 if (pidstr == NULL) { 1356 fprintf(stderr, "%s not set, cannot kill agent\n", 1357 SSH_AGENTPID_ENV_NAME); 1358 exit(1); 1359 } 1360 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1361 if (errstr) { 1362 fprintf(stderr, 1363 "%s=\"%s\", which is not a good PID: %s\n", 1364 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1365 exit(1); 1366 } 1367 if (kill(pid, SIGTERM) == -1) { 1368 perror("kill"); 1369 exit(1); 1370 } 1371 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1372 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1373 printf(format, SSH_AGENTPID_ENV_NAME); 1374 printf("echo Agent pid %ld killed;\n", (long)pid); 1375 exit(0); 1376 } 1377 1378 /* 1379 * Minimum file descriptors: 1380 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1381 * a few spare for libc / stack protectors / sanitisers, etc. 1382 */ 1383 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1384 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1385 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1386 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1387 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1388 1389 parent_pid = getpid(); 1390 1391 if (agentsocket == NULL) { 1392 /* Create private directory for agent socket */ 1393 mktemp_proto(socket_dir, sizeof(socket_dir)); 1394 if (mkdtemp(socket_dir) == NULL) { 1395 perror("mkdtemp: private socket dir"); 1396 exit(1); 1397 } 1398 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1399 (long)parent_pid); 1400 } else { 1401 /* Try to use specified agent socket */ 1402 socket_dir[0] = '\0'; 1403 strlcpy(socket_name, agentsocket, sizeof socket_name); 1404 } 1405 1406 /* 1407 * Create socket early so it will exist before command gets run from 1408 * the parent. 1409 */ 1410 prev_mask = umask(0177); 1411 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1412 if (sock < 0) { 1413 /* XXX - unix_listener() calls error() not perror() */ 1414 *socket_name = '\0'; /* Don't unlink any existing file */ 1415 cleanup_exit(1); 1416 } 1417 umask(prev_mask); 1418 1419 /* 1420 * Fork, and have the parent execute the command, if any, or present 1421 * the socket data. The child continues as the authentication agent. 1422 */ 1423 if (D_flag || d_flag) { 1424 log_init(__progname, 1425 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1426 SYSLOG_FACILITY_AUTH, 1); 1427 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1428 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1429 SSH_AUTHSOCKET_ENV_NAME); 1430 printf("echo Agent pid %ld;\n", (long)parent_pid); 1431 fflush(stdout); 1432 goto skip; 1433 } 1434 pid = fork(); 1435 if (pid == -1) { 1436 perror("fork"); 1437 cleanup_exit(1); 1438 } 1439 if (pid != 0) { /* Parent - execute the given command. */ 1440 close(sock); 1441 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1442 if (ac == 0) { 1443 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1444 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1445 SSH_AUTHSOCKET_ENV_NAME); 1446 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1447 SSH_AGENTPID_ENV_NAME); 1448 printf("echo Agent pid %ld;\n", (long)pid); 1449 exit(0); 1450 } 1451 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1452 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1453 perror("setenv"); 1454 exit(1); 1455 } 1456 execvp(av[0], av); 1457 perror(av[0]); 1458 exit(1); 1459 } 1460 /* child */ 1461 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1462 1463 if (setsid() == -1) { 1464 error("setsid: %s", strerror(errno)); 1465 cleanup_exit(1); 1466 } 1467 1468 (void)chdir("/"); 1469 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1470 /* XXX might close listen socket */ 1471 (void)dup2(fd, STDIN_FILENO); 1472 (void)dup2(fd, STDOUT_FILENO); 1473 (void)dup2(fd, STDERR_FILENO); 1474 if (fd > 2) 1475 close(fd); 1476 } 1477 1478 /* deny core dumps, since memory contains unencrypted private keys */ 1479 rlim.rlim_cur = rlim.rlim_max = 0; 1480 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1481 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1482 cleanup_exit(1); 1483 } 1484 1485 skip: 1486 1487 cleanup_pid = getpid(); 1488 1489 #ifdef ENABLE_PKCS11 1490 pkcs11_init(0); 1491 #endif 1492 new_socket(AUTH_SOCKET, sock); 1493 if (ac > 0) 1494 parent_alive_interval = 10; 1495 idtab_init(); 1496 ssh_signal(SIGPIPE, SIG_IGN); 1497 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1498 ssh_signal(SIGHUP, cleanup_handler); 1499 ssh_signal(SIGTERM, cleanup_handler); 1500 1501 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1502 fatal("%s: pledge: %s", __progname, strerror(errno)); 1503 1504 while (1) { 1505 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1506 result = poll(pfd, npfd, timeout); 1507 saved_errno = errno; 1508 if (parent_alive_interval != 0) 1509 check_parent_exists(); 1510 (void) reaper(); /* remove expired keys */ 1511 if (result == -1) { 1512 if (saved_errno == EINTR) 1513 continue; 1514 fatal("poll: %s", strerror(saved_errno)); 1515 } else if (result > 0) 1516 after_poll(pfd, npfd, maxfds); 1517 } 1518 /* NOTREACHED */ 1519 } 1520