1 /* $OpenBSD: ssh-agent.c,v 1.265 2020/10/03 09:22:26 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 /* XXX support PIN required FIDO keys */ 397 if ((r = sshkey_sign(id->key, &signature, &slen, 398 data, dlen, agent_decode_alg(key, flags), 399 id->sk_provider, NULL, compat)) != 0) { 400 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 401 goto send; 402 } 403 /* Success */ 404 ok = 0; 405 send: 406 notify_complete(notifier); 407 sshkey_free(key); 408 free(fp); 409 if (ok == 0) { 410 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 411 (r = sshbuf_put_string(msg, signature, slen)) != 0) 412 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 413 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 414 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 415 416 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 417 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 418 419 sshbuf_free(msg); 420 free(signature); 421 } 422 423 /* shared */ 424 static void 425 process_remove_identity(SocketEntry *e) 426 { 427 int r, success = 0; 428 struct sshkey *key = NULL; 429 Identity *id; 430 431 if ((r = sshkey_froms(e->request, &key)) != 0) { 432 error("%s: get key: %s", __func__, ssh_err(r)); 433 goto done; 434 } 435 if ((id = lookup_identity(key)) == NULL) { 436 debug("%s: key not found", __func__); 437 goto done; 438 } 439 /* We have this key, free it. */ 440 if (idtab->nentries < 1) 441 fatal("%s: internal error: nentries %d", 442 __func__, idtab->nentries); 443 TAILQ_REMOVE(&idtab->idlist, id, next); 444 free_identity(id); 445 idtab->nentries--; 446 sshkey_free(key); 447 success = 1; 448 done: 449 send_status(e, success); 450 } 451 452 static void 453 process_remove_all_identities(SocketEntry *e) 454 { 455 Identity *id; 456 457 /* Loop over all identities and clear the keys. */ 458 for (id = TAILQ_FIRST(&idtab->idlist); id; 459 id = TAILQ_FIRST(&idtab->idlist)) { 460 TAILQ_REMOVE(&idtab->idlist, id, next); 461 free_identity(id); 462 } 463 464 /* Mark that there are no identities. */ 465 idtab->nentries = 0; 466 467 /* Send success. */ 468 send_status(e, 1); 469 } 470 471 /* removes expired keys and returns number of seconds until the next expiry */ 472 static time_t 473 reaper(void) 474 { 475 time_t deadline = 0, now = monotime(); 476 Identity *id, *nxt; 477 478 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 479 nxt = TAILQ_NEXT(id, next); 480 if (id->death == 0) 481 continue; 482 if (now >= id->death) { 483 debug("expiring key '%s'", id->comment); 484 TAILQ_REMOVE(&idtab->idlist, id, next); 485 free_identity(id); 486 idtab->nentries--; 487 } else 488 deadline = (deadline == 0) ? id->death : 489 MINIMUM(deadline, id->death); 490 } 491 if (deadline == 0 || deadline <= now) 492 return 0; 493 else 494 return (deadline - now); 495 } 496 497 static void 498 process_add_identity(SocketEntry *e) 499 { 500 Identity *id; 501 int success = 0, confirm = 0; 502 u_int seconds = 0, maxsign; 503 char *fp, *comment = NULL, *ext_name = NULL, *sk_provider = NULL; 504 char canonical_provider[PATH_MAX]; 505 time_t death = 0; 506 struct sshkey *k = NULL; 507 u_char ctype; 508 int r = SSH_ERR_INTERNAL_ERROR; 509 510 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 511 k == NULL || 512 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 513 error("%s: decode private key: %s", __func__, ssh_err(r)); 514 goto err; 515 } 516 while (sshbuf_len(e->request)) { 517 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 518 error("%s: buffer error: %s", __func__, ssh_err(r)); 519 goto err; 520 } 521 switch (ctype) { 522 case SSH_AGENT_CONSTRAIN_LIFETIME: 523 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 524 error("%s: bad lifetime constraint: %s", 525 __func__, ssh_err(r)); 526 goto err; 527 } 528 death = monotime() + seconds; 529 break; 530 case SSH_AGENT_CONSTRAIN_CONFIRM: 531 confirm = 1; 532 break; 533 case SSH_AGENT_CONSTRAIN_MAXSIGN: 534 if ((r = sshbuf_get_u32(e->request, &maxsign)) != 0) { 535 error("%s: bad maxsign constraint: %s", 536 __func__, ssh_err(r)); 537 goto err; 538 } 539 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 540 error("%s: cannot enable maxsign: %s", 541 __func__, ssh_err(r)); 542 goto err; 543 } 544 break; 545 case SSH_AGENT_CONSTRAIN_EXTENSION: 546 if ((r = sshbuf_get_cstring(e->request, 547 &ext_name, NULL)) != 0) { 548 error("%s: cannot parse extension: %s", 549 __func__, ssh_err(r)); 550 goto err; 551 } 552 debug("%s: constraint ext %s", __func__, ext_name); 553 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 554 if (sk_provider != NULL) { 555 error("%s already set", ext_name); 556 goto err; 557 } 558 if ((r = sshbuf_get_cstring(e->request, 559 &sk_provider, NULL)) != 0) { 560 error("%s: cannot parse %s: %s", 561 __func__, ext_name, ssh_err(r)); 562 goto err; 563 } 564 } else { 565 error("%s: unsupported constraint \"%s\"", 566 __func__, ext_name); 567 goto err; 568 } 569 free(ext_name); 570 break; 571 default: 572 error("%s: Unknown constraint %d", __func__, ctype); 573 err: 574 free(sk_provider); 575 free(ext_name); 576 sshbuf_reset(e->request); 577 free(comment); 578 sshkey_free(k); 579 goto send; 580 } 581 } 582 if (sk_provider != NULL) { 583 if (!sshkey_is_sk(k)) { 584 error("Cannot add provider: %s is not an " 585 "authenticator-hosted key", sshkey_type(k)); 586 free(sk_provider); 587 goto send; 588 } 589 if (strcasecmp(sk_provider, "internal") == 0) { 590 debug("%s: internal provider", __func__); 591 } else { 592 if (realpath(sk_provider, canonical_provider) == NULL) { 593 verbose("failed provider \"%.100s\": " 594 "realpath: %s", sk_provider, 595 strerror(errno)); 596 free(sk_provider); 597 goto send; 598 } 599 free(sk_provider); 600 sk_provider = xstrdup(canonical_provider); 601 if (match_pattern_list(sk_provider, 602 allowed_providers, 0) != 1) { 603 error("Refusing add key: " 604 "provider %s not allowed", sk_provider); 605 free(sk_provider); 606 goto send; 607 } 608 } 609 } 610 if ((r = sshkey_shield_private(k)) != 0) { 611 error("%s: shield private key: %s", __func__, ssh_err(r)); 612 goto err; 613 } 614 615 success = 1; 616 if (lifetime && !death) 617 death = monotime() + lifetime; 618 if ((id = lookup_identity(k)) == NULL) { 619 id = xcalloc(1, sizeof(Identity)); 620 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 621 /* Increment the number of identities. */ 622 idtab->nentries++; 623 } else { 624 /* key state might have been updated */ 625 sshkey_free(id->key); 626 free(id->comment); 627 free(id->sk_provider); 628 } 629 id->key = k; 630 id->comment = comment; 631 id->death = death; 632 id->confirm = confirm; 633 id->sk_provider = sk_provider; 634 635 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 636 SSH_FP_DEFAULT)) == NULL) 637 fatal("%s: sshkey_fingerprint failed", __func__); 638 debug("%s: add %s %s \"%.100s\" (life: %u) (confirm: %u) " 639 "(provider: %s)", __func__, sshkey_ssh_name(k), fp, comment, 640 seconds, confirm, sk_provider == NULL ? "none" : sk_provider); 641 free(fp); 642 send: 643 send_status(e, success); 644 } 645 646 /* XXX todo: encrypt sensitive data with passphrase */ 647 static void 648 process_lock_agent(SocketEntry *e, int lock) 649 { 650 int r, success = 0, delay; 651 char *passwd; 652 u_char passwdhash[LOCK_SIZE]; 653 static u_int fail_count = 0; 654 size_t pwlen; 655 656 /* 657 * This is deliberately fatal: the user has requested that we lock, 658 * but we can't parse their request properly. The only safe thing to 659 * do is abort. 660 */ 661 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 662 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 663 if (pwlen == 0) { 664 debug("empty password not supported"); 665 } else if (locked && !lock) { 666 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 667 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 668 fatal("bcrypt_pbkdf"); 669 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 670 debug("agent unlocked"); 671 locked = 0; 672 fail_count = 0; 673 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 674 success = 1; 675 } else { 676 /* delay in 0.1s increments up to 10s */ 677 if (fail_count < 100) 678 fail_count++; 679 delay = 100000 * fail_count; 680 debug("unlock failed, delaying %0.1lf seconds", 681 (double)delay/1000000); 682 usleep(delay); 683 } 684 explicit_bzero(passwdhash, sizeof(passwdhash)); 685 } else if (!locked && lock) { 686 debug("agent locked"); 687 locked = 1; 688 arc4random_buf(lock_salt, sizeof(lock_salt)); 689 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 690 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 691 fatal("bcrypt_pbkdf"); 692 success = 1; 693 } 694 freezero(passwd, pwlen); 695 send_status(e, success); 696 } 697 698 static void 699 no_identities(SocketEntry *e) 700 { 701 struct sshbuf *msg; 702 int r; 703 704 if ((msg = sshbuf_new()) == NULL) 705 fatal("%s: sshbuf_new failed", __func__); 706 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 707 (r = sshbuf_put_u32(msg, 0)) != 0 || 708 (r = sshbuf_put_stringb(e->output, msg)) != 0) 709 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 710 sshbuf_free(msg); 711 } 712 713 #ifdef ENABLE_PKCS11 714 static void 715 process_add_smartcard_key(SocketEntry *e) 716 { 717 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 718 char **comments = NULL; 719 int r, i, count = 0, success = 0, confirm = 0; 720 u_int seconds; 721 time_t death = 0; 722 u_char type; 723 struct sshkey **keys = NULL, *k; 724 Identity *id; 725 726 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 727 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 728 error("%s: buffer error: %s", __func__, ssh_err(r)); 729 goto send; 730 } 731 732 while (sshbuf_len(e->request)) { 733 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 734 error("%s: buffer error: %s", __func__, ssh_err(r)); 735 goto send; 736 } 737 switch (type) { 738 case SSH_AGENT_CONSTRAIN_LIFETIME: 739 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 740 error("%s: buffer error: %s", 741 __func__, ssh_err(r)); 742 goto send; 743 } 744 death = monotime() + seconds; 745 break; 746 case SSH_AGENT_CONSTRAIN_CONFIRM: 747 confirm = 1; 748 break; 749 default: 750 error("%s: Unknown constraint type %d", __func__, type); 751 goto send; 752 } 753 } 754 if (realpath(provider, canonical_provider) == NULL) { 755 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 756 provider, strerror(errno)); 757 goto send; 758 } 759 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 760 verbose("refusing PKCS#11 add of \"%.100s\": " 761 "provider not allowed", canonical_provider); 762 goto send; 763 } 764 debug("%s: add %.100s", __func__, canonical_provider); 765 if (lifetime && !death) 766 death = monotime() + lifetime; 767 768 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 769 for (i = 0; i < count; i++) { 770 k = keys[i]; 771 if (lookup_identity(k) == NULL) { 772 id = xcalloc(1, sizeof(Identity)); 773 id->key = k; 774 keys[i] = NULL; /* transferred */ 775 id->provider = xstrdup(canonical_provider); 776 if (*comments[i] != '\0') { 777 id->comment = comments[i]; 778 comments[i] = NULL; /* transferred */ 779 } else { 780 id->comment = xstrdup(canonical_provider); 781 } 782 id->death = death; 783 id->confirm = confirm; 784 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 785 idtab->nentries++; 786 success = 1; 787 } 788 sshkey_free(keys[i]); 789 free(comments[i]); 790 } 791 send: 792 free(pin); 793 free(provider); 794 free(keys); 795 free(comments); 796 send_status(e, success); 797 } 798 799 static void 800 process_remove_smartcard_key(SocketEntry *e) 801 { 802 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 803 int r, success = 0; 804 Identity *id, *nxt; 805 806 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 807 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 808 error("%s: buffer error: %s", __func__, ssh_err(r)); 809 goto send; 810 } 811 free(pin); 812 813 if (realpath(provider, canonical_provider) == NULL) { 814 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 815 provider, strerror(errno)); 816 goto send; 817 } 818 819 debug("%s: remove %.100s", __func__, canonical_provider); 820 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 821 nxt = TAILQ_NEXT(id, next); 822 /* Skip file--based keys */ 823 if (id->provider == NULL) 824 continue; 825 if (!strcmp(canonical_provider, id->provider)) { 826 TAILQ_REMOVE(&idtab->idlist, id, next); 827 free_identity(id); 828 idtab->nentries--; 829 } 830 } 831 if (pkcs11_del_provider(canonical_provider) == 0) 832 success = 1; 833 else 834 error("%s: pkcs11_del_provider failed", __func__); 835 send: 836 free(provider); 837 send_status(e, success); 838 } 839 #endif /* ENABLE_PKCS11 */ 840 841 /* 842 * dispatch incoming message. 843 * returns 1 on success, 0 for incomplete messages or -1 on error. 844 */ 845 static int 846 process_message(u_int socknum) 847 { 848 u_int msg_len; 849 u_char type; 850 const u_char *cp; 851 int r; 852 SocketEntry *e; 853 854 if (socknum >= sockets_alloc) { 855 fatal("%s: socket number %u >= allocated %u", 856 __func__, socknum, sockets_alloc); 857 } 858 e = &sockets[socknum]; 859 860 if (sshbuf_len(e->input) < 5) 861 return 0; /* Incomplete message header. */ 862 cp = sshbuf_ptr(e->input); 863 msg_len = PEEK_U32(cp); 864 if (msg_len > AGENT_MAX_LEN) { 865 debug("%s: socket %u (fd=%d) message too long %u > %u", 866 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 867 return -1; 868 } 869 if (sshbuf_len(e->input) < msg_len + 4) 870 return 0; /* Incomplete message body. */ 871 872 /* move the current input to e->request */ 873 sshbuf_reset(e->request); 874 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 875 (r = sshbuf_get_u8(e->request, &type)) != 0) { 876 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 877 r == SSH_ERR_STRING_TOO_LARGE) { 878 debug("%s: buffer error: %s", __func__, ssh_err(r)); 879 return -1; 880 } 881 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 882 } 883 884 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 885 886 /* check whether agent is locked */ 887 if (locked && type != SSH_AGENTC_UNLOCK) { 888 sshbuf_reset(e->request); 889 switch (type) { 890 case SSH2_AGENTC_REQUEST_IDENTITIES: 891 /* send empty lists */ 892 no_identities(e); 893 break; 894 default: 895 /* send a fail message for all other request types */ 896 send_status(e, 0); 897 } 898 return 1; 899 } 900 901 switch (type) { 902 case SSH_AGENTC_LOCK: 903 case SSH_AGENTC_UNLOCK: 904 process_lock_agent(e, type == SSH_AGENTC_LOCK); 905 break; 906 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 907 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 908 break; 909 /* ssh2 */ 910 case SSH2_AGENTC_SIGN_REQUEST: 911 process_sign_request2(e); 912 break; 913 case SSH2_AGENTC_REQUEST_IDENTITIES: 914 process_request_identities(e); 915 break; 916 case SSH2_AGENTC_ADD_IDENTITY: 917 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 918 process_add_identity(e); 919 break; 920 case SSH2_AGENTC_REMOVE_IDENTITY: 921 process_remove_identity(e); 922 break; 923 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 924 process_remove_all_identities(e); 925 break; 926 #ifdef ENABLE_PKCS11 927 case SSH_AGENTC_ADD_SMARTCARD_KEY: 928 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 929 process_add_smartcard_key(e); 930 break; 931 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 932 process_remove_smartcard_key(e); 933 break; 934 #endif /* ENABLE_PKCS11 */ 935 default: 936 /* Unknown message. Respond with failure. */ 937 error("Unknown message %d", type); 938 sshbuf_reset(e->request); 939 send_status(e, 0); 940 break; 941 } 942 return 1; 943 } 944 945 static void 946 new_socket(sock_type type, int fd) 947 { 948 u_int i, old_alloc, new_alloc; 949 950 set_nonblock(fd); 951 952 if (fd > max_fd) 953 max_fd = fd; 954 955 for (i = 0; i < sockets_alloc; i++) 956 if (sockets[i].type == AUTH_UNUSED) { 957 sockets[i].fd = fd; 958 if ((sockets[i].input = sshbuf_new()) == NULL) 959 fatal("%s: sshbuf_new failed", __func__); 960 if ((sockets[i].output = sshbuf_new()) == NULL) 961 fatal("%s: sshbuf_new failed", __func__); 962 if ((sockets[i].request = sshbuf_new()) == NULL) 963 fatal("%s: sshbuf_new failed", __func__); 964 sockets[i].type = type; 965 return; 966 } 967 old_alloc = sockets_alloc; 968 new_alloc = sockets_alloc + 10; 969 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 970 for (i = old_alloc; i < new_alloc; i++) 971 sockets[i].type = AUTH_UNUSED; 972 sockets_alloc = new_alloc; 973 sockets[old_alloc].fd = fd; 974 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 975 fatal("%s: sshbuf_new failed", __func__); 976 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 977 fatal("%s: sshbuf_new failed", __func__); 978 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 979 fatal("%s: sshbuf_new failed", __func__); 980 sockets[old_alloc].type = type; 981 } 982 983 static int 984 handle_socket_read(u_int socknum) 985 { 986 struct sockaddr_un sunaddr; 987 socklen_t slen; 988 uid_t euid; 989 gid_t egid; 990 int fd; 991 992 slen = sizeof(sunaddr); 993 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 994 if (fd == -1) { 995 error("accept from AUTH_SOCKET: %s", strerror(errno)); 996 return -1; 997 } 998 if (getpeereid(fd, &euid, &egid) == -1) { 999 error("getpeereid %d failed: %s", fd, strerror(errno)); 1000 close(fd); 1001 return -1; 1002 } 1003 if ((euid != 0) && (getuid() != euid)) { 1004 error("uid mismatch: peer euid %u != uid %u", 1005 (u_int) euid, (u_int) getuid()); 1006 close(fd); 1007 return -1; 1008 } 1009 new_socket(AUTH_CONNECTION, fd); 1010 return 0; 1011 } 1012 1013 static int 1014 handle_conn_read(u_int socknum) 1015 { 1016 char buf[AGENT_RBUF_LEN]; 1017 ssize_t len; 1018 int r; 1019 1020 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1021 if (len == -1) { 1022 if (errno == EAGAIN || errno == EINTR) 1023 return 0; 1024 error("%s: read error on socket %u (fd %d): %s", 1025 __func__, socknum, sockets[socknum].fd, 1026 strerror(errno)); 1027 } 1028 return -1; 1029 } 1030 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1031 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1032 explicit_bzero(buf, sizeof(buf)); 1033 for (;;) { 1034 if ((r = process_message(socknum)) == -1) 1035 return -1; 1036 else if (r == 0) 1037 break; 1038 } 1039 return 0; 1040 } 1041 1042 static int 1043 handle_conn_write(u_int socknum) 1044 { 1045 ssize_t len; 1046 int r; 1047 1048 if (sshbuf_len(sockets[socknum].output) == 0) 1049 return 0; /* shouldn't happen */ 1050 if ((len = write(sockets[socknum].fd, 1051 sshbuf_ptr(sockets[socknum].output), 1052 sshbuf_len(sockets[socknum].output))) <= 0) { 1053 if (len == -1) { 1054 if (errno == EAGAIN || errno == EINTR) 1055 return 0; 1056 error("%s: read error on socket %u (fd %d): %s", 1057 __func__, socknum, sockets[socknum].fd, 1058 strerror(errno)); 1059 } 1060 return -1; 1061 } 1062 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1063 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1064 return 0; 1065 } 1066 1067 static void 1068 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1069 { 1070 size_t i; 1071 u_int socknum, activefds = npfd; 1072 1073 for (i = 0; i < npfd; i++) { 1074 if (pfd[i].revents == 0) 1075 continue; 1076 /* Find sockets entry */ 1077 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1078 if (sockets[socknum].type != AUTH_SOCKET && 1079 sockets[socknum].type != AUTH_CONNECTION) 1080 continue; 1081 if (pfd[i].fd == sockets[socknum].fd) 1082 break; 1083 } 1084 if (socknum >= sockets_alloc) { 1085 error("%s: no socket for fd %d", __func__, pfd[i].fd); 1086 continue; 1087 } 1088 /* Process events */ 1089 switch (sockets[socknum].type) { 1090 case AUTH_SOCKET: 1091 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1092 break; 1093 if (npfd > maxfds) { 1094 debug3("out of fds (active %u >= limit %u); " 1095 "skipping accept", activefds, maxfds); 1096 break; 1097 } 1098 if (handle_socket_read(socknum) == 0) 1099 activefds++; 1100 break; 1101 case AUTH_CONNECTION: 1102 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1103 handle_conn_read(socknum) != 0) { 1104 goto close_sock; 1105 } 1106 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1107 handle_conn_write(socknum) != 0) { 1108 close_sock: 1109 if (activefds == 0) 1110 fatal("activefds == 0 at close_sock"); 1111 close_socket(&sockets[socknum]); 1112 activefds--; 1113 break; 1114 } 1115 break; 1116 default: 1117 break; 1118 } 1119 } 1120 } 1121 1122 static int 1123 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1124 { 1125 struct pollfd *pfd = *pfdp; 1126 size_t i, j, npfd = 0; 1127 time_t deadline; 1128 int r; 1129 1130 /* Count active sockets */ 1131 for (i = 0; i < sockets_alloc; i++) { 1132 switch (sockets[i].type) { 1133 case AUTH_SOCKET: 1134 case AUTH_CONNECTION: 1135 npfd++; 1136 break; 1137 case AUTH_UNUSED: 1138 break; 1139 default: 1140 fatal("Unknown socket type %d", sockets[i].type); 1141 break; 1142 } 1143 } 1144 if (npfd != *npfdp && 1145 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1146 fatal("%s: recallocarray failed", __func__); 1147 *pfdp = pfd; 1148 *npfdp = npfd; 1149 1150 for (i = j = 0; i < sockets_alloc; i++) { 1151 switch (sockets[i].type) { 1152 case AUTH_SOCKET: 1153 if (npfd > maxfds) { 1154 debug3("out of fds (active %zu >= limit %u); " 1155 "skipping arming listener", npfd, maxfds); 1156 break; 1157 } 1158 pfd[j].fd = sockets[i].fd; 1159 pfd[j].revents = 0; 1160 pfd[j].events = POLLIN; 1161 j++; 1162 break; 1163 case AUTH_CONNECTION: 1164 pfd[j].fd = sockets[i].fd; 1165 pfd[j].revents = 0; 1166 /* 1167 * Only prepare to read if we can handle a full-size 1168 * input read buffer and enqueue a max size reply.. 1169 */ 1170 if ((r = sshbuf_check_reserve(sockets[i].input, 1171 AGENT_RBUF_LEN)) == 0 && 1172 (r = sshbuf_check_reserve(sockets[i].output, 1173 AGENT_MAX_LEN)) == 0) 1174 pfd[j].events = POLLIN; 1175 else if (r != SSH_ERR_NO_BUFFER_SPACE) { 1176 fatal("%s: buffer error: %s", 1177 __func__, ssh_err(r)); 1178 } 1179 if (sshbuf_len(sockets[i].output) > 0) 1180 pfd[j].events |= POLLOUT; 1181 j++; 1182 break; 1183 default: 1184 break; 1185 } 1186 } 1187 deadline = reaper(); 1188 if (parent_alive_interval != 0) 1189 deadline = (deadline == 0) ? parent_alive_interval : 1190 MINIMUM(deadline, parent_alive_interval); 1191 if (deadline == 0) { 1192 *timeoutp = -1; /* INFTIM */ 1193 } else { 1194 if (deadline > INT_MAX / 1000) 1195 *timeoutp = INT_MAX / 1000; 1196 else 1197 *timeoutp = deadline * 1000; 1198 } 1199 return (1); 1200 } 1201 1202 static void 1203 cleanup_socket(void) 1204 { 1205 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1206 return; 1207 debug("%s: cleanup", __func__); 1208 if (socket_name[0]) 1209 unlink(socket_name); 1210 if (socket_dir[0]) 1211 rmdir(socket_dir); 1212 } 1213 1214 void 1215 cleanup_exit(int i) 1216 { 1217 cleanup_socket(); 1218 _exit(i); 1219 } 1220 1221 /*ARGSUSED*/ 1222 static void 1223 cleanup_handler(int sig) 1224 { 1225 cleanup_socket(); 1226 #ifdef ENABLE_PKCS11 1227 pkcs11_terminate(); 1228 #endif 1229 _exit(2); 1230 } 1231 1232 static void 1233 check_parent_exists(void) 1234 { 1235 /* 1236 * If our parent has exited then getppid() will return (pid_t)1, 1237 * so testing for that should be safe. 1238 */ 1239 if (parent_pid != -1 && getppid() != parent_pid) { 1240 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1241 cleanup_socket(); 1242 _exit(2); 1243 } 1244 } 1245 1246 static void 1247 usage(void) 1248 { 1249 fprintf(stderr, 1250 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1251 " [-P allowed_providers] [-t life]\n" 1252 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1253 " [-t life] command [arg ...]\n" 1254 " ssh-agent [-c | -s] -k\n"); 1255 exit(1); 1256 } 1257 1258 int 1259 main(int ac, char **av) 1260 { 1261 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1262 int sock, ch, result, saved_errno; 1263 char *shell, *format, *pidstr, *agentsocket = NULL; 1264 struct rlimit rlim; 1265 extern int optind; 1266 extern char *optarg; 1267 pid_t pid; 1268 char pidstrbuf[1 + 3 * sizeof pid]; 1269 size_t len; 1270 mode_t prev_mask; 1271 int timeout = -1; /* INFTIM */ 1272 struct pollfd *pfd = NULL; 1273 size_t npfd = 0; 1274 u_int maxfds; 1275 1276 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1277 sanitise_stdfd(); 1278 1279 /* drop */ 1280 setegid(getgid()); 1281 setgid(getgid()); 1282 1283 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1284 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1285 1286 #ifdef WITH_OPENSSL 1287 OpenSSL_add_all_algorithms(); 1288 #endif 1289 1290 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1291 switch (ch) { 1292 case 'E': 1293 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1294 if (fingerprint_hash == -1) 1295 fatal("Invalid hash algorithm \"%s\"", optarg); 1296 break; 1297 case 'c': 1298 if (s_flag) 1299 usage(); 1300 c_flag++; 1301 break; 1302 case 'k': 1303 k_flag++; 1304 break; 1305 case 'O': 1306 if (strcmp(optarg, "no-restrict-websafe") == 0) 1307 restrict_websafe = 0; 1308 else 1309 fatal("Unknown -O option"); 1310 break; 1311 case 'P': 1312 if (allowed_providers != NULL) 1313 fatal("-P option already specified"); 1314 allowed_providers = xstrdup(optarg); 1315 break; 1316 case 's': 1317 if (c_flag) 1318 usage(); 1319 s_flag++; 1320 break; 1321 case 'd': 1322 if (d_flag || D_flag) 1323 usage(); 1324 d_flag++; 1325 break; 1326 case 'D': 1327 if (d_flag || D_flag) 1328 usage(); 1329 D_flag++; 1330 break; 1331 case 'a': 1332 agentsocket = optarg; 1333 break; 1334 case 't': 1335 if ((lifetime = convtime(optarg)) == -1) { 1336 fprintf(stderr, "Invalid lifetime\n"); 1337 usage(); 1338 } 1339 break; 1340 default: 1341 usage(); 1342 } 1343 } 1344 ac -= optind; 1345 av += optind; 1346 1347 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1348 usage(); 1349 1350 if (allowed_providers == NULL) 1351 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1352 1353 if (ac == 0 && !c_flag && !s_flag) { 1354 shell = getenv("SHELL"); 1355 if (shell != NULL && (len = strlen(shell)) > 2 && 1356 strncmp(shell + len - 3, "csh", 3) == 0) 1357 c_flag = 1; 1358 } 1359 if (k_flag) { 1360 const char *errstr = NULL; 1361 1362 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1363 if (pidstr == NULL) { 1364 fprintf(stderr, "%s not set, cannot kill agent\n", 1365 SSH_AGENTPID_ENV_NAME); 1366 exit(1); 1367 } 1368 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1369 if (errstr) { 1370 fprintf(stderr, 1371 "%s=\"%s\", which is not a good PID: %s\n", 1372 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1373 exit(1); 1374 } 1375 if (kill(pid, SIGTERM) == -1) { 1376 perror("kill"); 1377 exit(1); 1378 } 1379 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1380 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1381 printf(format, SSH_AGENTPID_ENV_NAME); 1382 printf("echo Agent pid %ld killed;\n", (long)pid); 1383 exit(0); 1384 } 1385 1386 /* 1387 * Minimum file descriptors: 1388 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1389 * a few spare for libc / stack protectors / sanitisers, etc. 1390 */ 1391 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1392 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1393 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1394 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1395 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1396 1397 parent_pid = getpid(); 1398 1399 if (agentsocket == NULL) { 1400 /* Create private directory for agent socket */ 1401 mktemp_proto(socket_dir, sizeof(socket_dir)); 1402 if (mkdtemp(socket_dir) == NULL) { 1403 perror("mkdtemp: private socket dir"); 1404 exit(1); 1405 } 1406 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1407 (long)parent_pid); 1408 } else { 1409 /* Try to use specified agent socket */ 1410 socket_dir[0] = '\0'; 1411 strlcpy(socket_name, agentsocket, sizeof socket_name); 1412 } 1413 1414 /* 1415 * Create socket early so it will exist before command gets run from 1416 * the parent. 1417 */ 1418 prev_mask = umask(0177); 1419 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1420 if (sock < 0) { 1421 /* XXX - unix_listener() calls error() not perror() */ 1422 *socket_name = '\0'; /* Don't unlink any existing file */ 1423 cleanup_exit(1); 1424 } 1425 umask(prev_mask); 1426 1427 /* 1428 * Fork, and have the parent execute the command, if any, or present 1429 * the socket data. The child continues as the authentication agent. 1430 */ 1431 if (D_flag || d_flag) { 1432 log_init(__progname, 1433 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1434 SYSLOG_FACILITY_AUTH, 1); 1435 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1436 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1437 SSH_AUTHSOCKET_ENV_NAME); 1438 printf("echo Agent pid %ld;\n", (long)parent_pid); 1439 fflush(stdout); 1440 goto skip; 1441 } 1442 pid = fork(); 1443 if (pid == -1) { 1444 perror("fork"); 1445 cleanup_exit(1); 1446 } 1447 if (pid != 0) { /* Parent - execute the given command. */ 1448 close(sock); 1449 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1450 if (ac == 0) { 1451 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1452 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1453 SSH_AUTHSOCKET_ENV_NAME); 1454 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1455 SSH_AGENTPID_ENV_NAME); 1456 printf("echo Agent pid %ld;\n", (long)pid); 1457 exit(0); 1458 } 1459 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1460 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1461 perror("setenv"); 1462 exit(1); 1463 } 1464 execvp(av[0], av); 1465 perror(av[0]); 1466 exit(1); 1467 } 1468 /* child */ 1469 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1470 1471 if (setsid() == -1) { 1472 error("setsid: %s", strerror(errno)); 1473 cleanup_exit(1); 1474 } 1475 1476 (void)chdir("/"); 1477 if (stdfd_devnull(1, 1, 1) == -1) 1478 error("%s: stdfd_devnull failed", __func__); 1479 1480 /* deny core dumps, since memory contains unencrypted private keys */ 1481 rlim.rlim_cur = rlim.rlim_max = 0; 1482 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1483 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1484 cleanup_exit(1); 1485 } 1486 1487 skip: 1488 1489 cleanup_pid = getpid(); 1490 1491 #ifdef ENABLE_PKCS11 1492 pkcs11_init(0); 1493 #endif 1494 new_socket(AUTH_SOCKET, sock); 1495 if (ac > 0) 1496 parent_alive_interval = 10; 1497 idtab_init(); 1498 ssh_signal(SIGPIPE, SIG_IGN); 1499 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1500 ssh_signal(SIGHUP, cleanup_handler); 1501 ssh_signal(SIGTERM, cleanup_handler); 1502 1503 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1504 fatal("%s: pledge: %s", __progname, strerror(errno)); 1505 1506 while (1) { 1507 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1508 result = poll(pfd, npfd, timeout); 1509 saved_errno = errno; 1510 if (parent_alive_interval != 0) 1511 check_parent_exists(); 1512 (void) reaper(); /* remove expired keys */ 1513 if (result == -1) { 1514 if (saved_errno == EINTR) 1515 continue; 1516 fatal("poll: %s", strerror(saved_errno)); 1517 } else if (result > 0) 1518 after_poll(pfd, npfd, maxfds); 1519 } 1520 /* NOTREACHED */ 1521 } 1522