1 /* $OpenBSD: ssh-agent.c,v 1.261 2020/06/22 06:37:38 jmc 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 "includes.h" 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #include <sys/resource.h> 42 #include <sys/stat.h> 43 #include <sys/socket.h> 44 #include <sys/wait.h> 45 #ifdef HAVE_SYS_TIME_H 46 # include <sys/time.h> 47 #endif 48 #ifdef HAVE_SYS_UN_H 49 # include <sys/un.h> 50 #endif 51 #include "openbsd-compat/sys-queue.h" 52 53 #ifdef WITH_OPENSSL 54 #include <openssl/evp.h> 55 #include "openbsd-compat/openssl-compat.h" 56 #endif 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <limits.h> 61 #ifdef HAVE_PATHS_H 62 # include <paths.h> 63 #endif 64 #ifdef HAVE_POLL_H 65 # include <poll.h> 66 #endif 67 #include <signal.h> 68 #include <stdarg.h> 69 #include <stdio.h> 70 #include <stdlib.h> 71 #include <time.h> 72 #include <string.h> 73 #include <unistd.h> 74 #ifdef HAVE_UTIL_H 75 # include <util.h> 76 #endif 77 78 #include "xmalloc.h" 79 #include "ssh.h" 80 #include "ssh2.h" 81 #include "sshbuf.h" 82 #include "sshkey.h" 83 #include "authfd.h" 84 #include "compat.h" 85 #include "log.h" 86 #include "misc.h" 87 #include "digest.h" 88 #include "ssherr.h" 89 #include "match.h" 90 #include "msg.h" 91 #include "ssherr.h" 92 #include "pathnames.h" 93 #include "ssh-pkcs11.h" 94 #include "sk-api.h" 95 96 #ifndef DEFAULT_PROVIDER_WHITELIST 97 # define DEFAULT_PROVIDER_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 98 #endif 99 100 /* Maximum accepted message length */ 101 #define AGENT_MAX_LEN (256*1024) 102 /* Maximum bytes to read from client socket */ 103 #define AGENT_RBUF_LEN (4096) 104 105 typedef enum { 106 AUTH_UNUSED, 107 AUTH_SOCKET, 108 AUTH_CONNECTION 109 } sock_type; 110 111 typedef struct { 112 int fd; 113 sock_type type; 114 struct sshbuf *input; 115 struct sshbuf *output; 116 struct sshbuf *request; 117 } SocketEntry; 118 119 u_int sockets_alloc = 0; 120 SocketEntry *sockets = NULL; 121 122 typedef struct identity { 123 TAILQ_ENTRY(identity) next; 124 struct sshkey *key; 125 char *comment; 126 char *provider; 127 time_t death; 128 u_int confirm; 129 char *sk_provider; 130 } Identity; 131 132 struct idtable { 133 int nentries; 134 TAILQ_HEAD(idqueue, identity) idlist; 135 }; 136 137 /* private key table */ 138 struct idtable *idtab; 139 140 int max_fd = 0; 141 142 /* pid of shell == parent of agent */ 143 pid_t parent_pid = -1; 144 time_t parent_alive_interval = 0; 145 146 /* pid of process for which cleanup_socket is applicable */ 147 pid_t cleanup_pid = 0; 148 149 /* pathname and directory for AUTH_SOCKET */ 150 char socket_name[PATH_MAX]; 151 char socket_dir[PATH_MAX]; 152 153 /* Pattern-list of allowed PKCS#11/Security key paths */ 154 static char *allowed_providers; 155 156 /* locking */ 157 #define LOCK_SIZE 32 158 #define LOCK_SALT_SIZE 16 159 #define LOCK_ROUNDS 1 160 int locked = 0; 161 u_char lock_pwhash[LOCK_SIZE]; 162 u_char lock_salt[LOCK_SALT_SIZE]; 163 164 extern char *__progname; 165 166 /* Default lifetime in seconds (0 == forever) */ 167 static long lifetime = 0; 168 169 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 170 171 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 172 static int restrict_websafe = 1; 173 174 static void 175 close_socket(SocketEntry *e) 176 { 177 close(e->fd); 178 e->fd = -1; 179 e->type = AUTH_UNUSED; 180 sshbuf_free(e->input); 181 sshbuf_free(e->output); 182 sshbuf_free(e->request); 183 } 184 185 static void 186 idtab_init(void) 187 { 188 idtab = xcalloc(1, sizeof(*idtab)); 189 TAILQ_INIT(&idtab->idlist); 190 idtab->nentries = 0; 191 } 192 193 static void 194 free_identity(Identity *id) 195 { 196 sshkey_free(id->key); 197 free(id->provider); 198 free(id->comment); 199 free(id->sk_provider); 200 free(id); 201 } 202 203 /* return matching private key for given public key */ 204 static Identity * 205 lookup_identity(struct sshkey *key) 206 { 207 Identity *id; 208 209 TAILQ_FOREACH(id, &idtab->idlist, next) { 210 if (sshkey_equal(key, id->key)) 211 return (id); 212 } 213 return (NULL); 214 } 215 216 /* Check confirmation of keysign request */ 217 static int 218 confirm_key(Identity *id) 219 { 220 char *p; 221 int ret = -1; 222 223 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 224 if (p != NULL && 225 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 226 id->comment, p)) 227 ret = 0; 228 free(p); 229 230 return (ret); 231 } 232 233 static void 234 send_status(SocketEntry *e, int success) 235 { 236 int r; 237 238 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 239 (r = sshbuf_put_u8(e->output, success ? 240 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 241 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 242 } 243 244 /* send list of supported public keys to 'client' */ 245 static void 246 process_request_identities(SocketEntry *e) 247 { 248 Identity *id; 249 struct sshbuf *msg; 250 int r; 251 252 if ((msg = sshbuf_new()) == NULL) 253 fatal("%s: sshbuf_new failed", __func__); 254 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 255 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 256 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 257 TAILQ_FOREACH(id, &idtab->idlist, next) { 258 if ((r = sshkey_puts_opts(id->key, msg, SSHKEY_SERIALIZE_INFO)) 259 != 0 || 260 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 261 error("%s: put key/comment: %s", __func__, 262 ssh_err(r)); 263 continue; 264 } 265 } 266 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 267 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 268 sshbuf_free(msg); 269 } 270 271 272 static char * 273 agent_decode_alg(struct sshkey *key, u_int flags) 274 { 275 if (key->type == KEY_RSA) { 276 if (flags & SSH_AGENT_RSA_SHA2_256) 277 return "rsa-sha2-256"; 278 else if (flags & SSH_AGENT_RSA_SHA2_512) 279 return "rsa-sha2-512"; 280 } else if (key->type == KEY_RSA_CERT) { 281 if (flags & SSH_AGENT_RSA_SHA2_256) 282 return "rsa-sha2-256-cert-v01@openssh.com"; 283 else if (flags & SSH_AGENT_RSA_SHA2_512) 284 return "rsa-sha2-512-cert-v01@openssh.com"; 285 } 286 return NULL; 287 } 288 289 /* 290 * This function inspects a message to be signed by a FIDO key that has a 291 * web-like application string (i.e. one that does not begin with "ssh:". 292 * It checks that the message is one of those expected for SSH operations 293 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 294 * for the web. 295 */ 296 static int 297 check_websafe_message_contents(struct sshkey *key, 298 const u_char *msg, size_t len) 299 { 300 int matched = 0; 301 struct sshbuf *b; 302 u_char m, n; 303 char *cp1 = NULL, *cp2 = NULL; 304 int r; 305 struct sshkey *mkey = NULL; 306 307 if ((b = sshbuf_from(msg, len)) == NULL) 308 fatal("%s: sshbuf_new", __func__); 309 310 /* SSH userauth request */ 311 if ((r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* sess_id */ 312 (r = sshbuf_get_u8(b, &m)) == 0 && /* SSH2_MSG_USERAUTH_REQUEST */ 313 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* server user */ 314 (r = sshbuf_get_cstring(b, &cp1, NULL)) == 0 && /* service */ 315 (r = sshbuf_get_cstring(b, &cp2, NULL)) == 0 && /* method */ 316 (r = sshbuf_get_u8(b, &n)) == 0 && /* sig-follows */ 317 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* alg */ 318 (r = sshkey_froms(b, &mkey)) == 0 && /* key */ 319 sshbuf_len(b) == 0) { 320 debug("%s: parsed userauth", __func__); 321 if (m == SSH2_MSG_USERAUTH_REQUEST && n == 1 && 322 strcmp(cp1, "ssh-connection") == 0 && 323 strcmp(cp2, "publickey") == 0 && 324 sshkey_equal(key, mkey)) { 325 debug("%s: well formed userauth", __func__); 326 matched = 1; 327 } 328 } 329 free(cp1); 330 free(cp2); 331 sshkey_free(mkey); 332 sshbuf_free(b); 333 if (matched) 334 return 1; 335 336 if ((b = sshbuf_from(msg, len)) == NULL) 337 fatal("%s: sshbuf_new", __func__); 338 cp1 = cp2 = NULL; 339 mkey = NULL; 340 341 /* SSHSIG */ 342 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) == 0 && 343 (r = sshbuf_consume(b, 6)) == 0 && 344 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* namespace */ 345 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* reserved */ 346 (r = sshbuf_get_cstring(b, NULL, NULL)) == 0 && /* hashalg */ 347 (r = sshbuf_get_string_direct(b, NULL, NULL)) == 0 && /* H(msg) */ 348 sshbuf_len(b) == 0) { 349 debug("%s: parsed sshsig", __func__); 350 matched = 1; 351 } 352 353 sshbuf_free(b); 354 if (matched) 355 return 1; 356 357 /* XXX CA signature operation */ 358 359 error("web-origin key attempting to sign non-SSH message"); 360 return 0; 361 } 362 363 /* ssh2 only */ 364 static void 365 process_sign_request2(SocketEntry *e) 366 { 367 const u_char *data; 368 u_char *signature = NULL; 369 size_t dlen, slen = 0; 370 u_int compat = 0, flags; 371 int r, ok = -1; 372 char *fp = NULL; 373 struct sshbuf *msg; 374 struct sshkey *key = NULL; 375 struct identity *id; 376 struct notifier_ctx *notifier = NULL; 377 378 if ((msg = sshbuf_new()) == NULL) 379 fatal("%s: sshbuf_new failed", __func__); 380 if ((r = sshkey_froms(e->request, &key)) != 0 || 381 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 382 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 383 error("%s: couldn't parse request: %s", __func__, ssh_err(r)); 384 goto send; 385 } 386 387 if ((id = lookup_identity(key)) == NULL) { 388 verbose("%s: %s key not found", __func__, sshkey_type(key)); 389 goto send; 390 } 391 if (id->confirm && confirm_key(id) != 0) { 392 verbose("%s: user refused key", __func__); 393 goto send; 394 } 395 if (sshkey_is_sk(id->key)) { 396 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 397 !check_websafe_message_contents(key, data, dlen)) { 398 /* error already logged */ 399 goto send; 400 } 401 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 402 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 403 SSH_FP_DEFAULT)) == NULL) 404 fatal("%s: fingerprint failed", __func__); 405 notifier = notify_start(0, 406 "Confirm user presence for key %s %s", 407 sshkey_type(id->key), fp); 408 } 409 } 410 if ((r = sshkey_sign(id->key, &signature, &slen, 411 data, dlen, agent_decode_alg(key, flags), 412 id->sk_provider, compat)) != 0) { 413 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 414 goto send; 415 } 416 /* Success */ 417 ok = 0; 418 send: 419 notify_complete(notifier); 420 sshkey_free(key); 421 free(fp); 422 if (ok == 0) { 423 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 424 (r = sshbuf_put_string(msg, signature, slen)) != 0) 425 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 426 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 427 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 428 429 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 430 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 431 432 sshbuf_free(msg); 433 free(signature); 434 } 435 436 /* shared */ 437 static void 438 process_remove_identity(SocketEntry *e) 439 { 440 int r, success = 0; 441 struct sshkey *key = NULL; 442 Identity *id; 443 444 if ((r = sshkey_froms(e->request, &key)) != 0) { 445 error("%s: get key: %s", __func__, ssh_err(r)); 446 goto done; 447 } 448 if ((id = lookup_identity(key)) == NULL) { 449 debug("%s: key not found", __func__); 450 goto done; 451 } 452 /* We have this key, free it. */ 453 if (idtab->nentries < 1) 454 fatal("%s: internal error: nentries %d", 455 __func__, idtab->nentries); 456 TAILQ_REMOVE(&idtab->idlist, id, next); 457 free_identity(id); 458 idtab->nentries--; 459 sshkey_free(key); 460 success = 1; 461 done: 462 send_status(e, success); 463 } 464 465 static void 466 process_remove_all_identities(SocketEntry *e) 467 { 468 Identity *id; 469 470 /* Loop over all identities and clear the keys. */ 471 for (id = TAILQ_FIRST(&idtab->idlist); id; 472 id = TAILQ_FIRST(&idtab->idlist)) { 473 TAILQ_REMOVE(&idtab->idlist, id, next); 474 free_identity(id); 475 } 476 477 /* Mark that there are no identities. */ 478 idtab->nentries = 0; 479 480 /* Send success. */ 481 send_status(e, 1); 482 } 483 484 /* removes expired keys and returns number of seconds until the next expiry */ 485 static time_t 486 reaper(void) 487 { 488 time_t deadline = 0, now = monotime(); 489 Identity *id, *nxt; 490 491 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 492 nxt = TAILQ_NEXT(id, next); 493 if (id->death == 0) 494 continue; 495 if (now >= id->death) { 496 debug("expiring key '%s'", id->comment); 497 TAILQ_REMOVE(&idtab->idlist, id, next); 498 free_identity(id); 499 idtab->nentries--; 500 } else 501 deadline = (deadline == 0) ? id->death : 502 MINIMUM(deadline, id->death); 503 } 504 if (deadline == 0 || deadline <= now) 505 return 0; 506 else 507 return (deadline - now); 508 } 509 510 static void 511 process_add_identity(SocketEntry *e) 512 { 513 Identity *id; 514 int success = 0, confirm = 0; 515 u_int seconds = 0, maxsign; 516 char *fp, *comment = NULL, *ext_name = NULL, *sk_provider = NULL; 517 char canonical_provider[PATH_MAX]; 518 time_t death = 0; 519 struct sshkey *k = NULL; 520 u_char ctype; 521 int r = SSH_ERR_INTERNAL_ERROR; 522 523 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 524 k == NULL || 525 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 526 error("%s: decode private key: %s", __func__, ssh_err(r)); 527 goto err; 528 } 529 while (sshbuf_len(e->request)) { 530 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 531 error("%s: buffer error: %s", __func__, ssh_err(r)); 532 goto err; 533 } 534 switch (ctype) { 535 case SSH_AGENT_CONSTRAIN_LIFETIME: 536 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 537 error("%s: bad lifetime constraint: %s", 538 __func__, ssh_err(r)); 539 goto err; 540 } 541 death = monotime() + seconds; 542 break; 543 case SSH_AGENT_CONSTRAIN_CONFIRM: 544 confirm = 1; 545 break; 546 case SSH_AGENT_CONSTRAIN_MAXSIGN: 547 if ((r = sshbuf_get_u32(e->request, &maxsign)) != 0) { 548 error("%s: bad maxsign constraint: %s", 549 __func__, ssh_err(r)); 550 goto err; 551 } 552 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 553 error("%s: cannot enable maxsign: %s", 554 __func__, ssh_err(r)); 555 goto err; 556 } 557 break; 558 case SSH_AGENT_CONSTRAIN_EXTENSION: 559 if ((r = sshbuf_get_cstring(e->request, 560 &ext_name, NULL)) != 0) { 561 error("%s: cannot parse extension: %s", 562 __func__, ssh_err(r)); 563 goto err; 564 } 565 debug("%s: constraint ext %s", __func__, ext_name); 566 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 567 if (sk_provider != NULL) { 568 error("%s already set", ext_name); 569 goto err; 570 } 571 if ((r = sshbuf_get_cstring(e->request, 572 &sk_provider, NULL)) != 0) { 573 error("%s: cannot parse %s: %s", 574 __func__, ext_name, ssh_err(r)); 575 goto err; 576 } 577 } else { 578 error("%s: unsupported constraint \"%s\"", 579 __func__, ext_name); 580 goto err; 581 } 582 free(ext_name); 583 break; 584 default: 585 error("%s: Unknown constraint %d", __func__, ctype); 586 err: 587 free(sk_provider); 588 free(ext_name); 589 sshbuf_reset(e->request); 590 free(comment); 591 sshkey_free(k); 592 goto send; 593 } 594 } 595 if (sk_provider != NULL) { 596 if (!sshkey_is_sk(k)) { 597 error("Cannot add provider: %s is not an " 598 "authenticator-hosted key", sshkey_type(k)); 599 free(sk_provider); 600 goto send; 601 } 602 if (strcasecmp(sk_provider, "internal") == 0) { 603 debug("%s: internal provider", __func__); 604 } else { 605 if (realpath(sk_provider, canonical_provider) == NULL) { 606 verbose("failed provider \"%.100s\": " 607 "realpath: %s", sk_provider, 608 strerror(errno)); 609 free(sk_provider); 610 goto send; 611 } 612 free(sk_provider); 613 sk_provider = xstrdup(canonical_provider); 614 if (match_pattern_list(sk_provider, 615 allowed_providers, 0) != 1) { 616 error("Refusing add key: " 617 "provider %s not allowed", sk_provider); 618 free(sk_provider); 619 goto send; 620 } 621 } 622 } 623 if ((r = sshkey_shield_private(k)) != 0) { 624 error("%s: shield private key: %s", __func__, ssh_err(r)); 625 goto err; 626 } 627 628 success = 1; 629 if (lifetime && !death) 630 death = monotime() + lifetime; 631 if ((id = lookup_identity(k)) == NULL) { 632 id = xcalloc(1, sizeof(Identity)); 633 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 634 /* Increment the number of identities. */ 635 idtab->nentries++; 636 } else { 637 /* key state might have been updated */ 638 sshkey_free(id->key); 639 free(id->comment); 640 free(id->sk_provider); 641 } 642 id->key = k; 643 id->comment = comment; 644 id->death = death; 645 id->confirm = confirm; 646 id->sk_provider = sk_provider; 647 648 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 649 SSH_FP_DEFAULT)) == NULL) 650 fatal("%s: sshkey_fingerprint failed", __func__); 651 debug("%s: add %s %s \"%.100s\" (life: %u) (confirm: %u) " 652 "(provider: %s)", __func__, sshkey_ssh_name(k), fp, comment, 653 seconds, confirm, sk_provider == NULL ? "none" : sk_provider); 654 free(fp); 655 send: 656 send_status(e, success); 657 } 658 659 /* XXX todo: encrypt sensitive data with passphrase */ 660 static void 661 process_lock_agent(SocketEntry *e, int lock) 662 { 663 int r, success = 0, delay; 664 char *passwd; 665 u_char passwdhash[LOCK_SIZE]; 666 static u_int fail_count = 0; 667 size_t pwlen; 668 669 /* 670 * This is deliberately fatal: the user has requested that we lock, 671 * but we can't parse their request properly. The only safe thing to 672 * do is abort. 673 */ 674 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 675 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 676 if (pwlen == 0) { 677 debug("empty password not supported"); 678 } else if (locked && !lock) { 679 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 680 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 681 fatal("bcrypt_pbkdf"); 682 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 683 debug("agent unlocked"); 684 locked = 0; 685 fail_count = 0; 686 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 687 success = 1; 688 } else { 689 /* delay in 0.1s increments up to 10s */ 690 if (fail_count < 100) 691 fail_count++; 692 delay = 100000 * fail_count; 693 debug("unlock failed, delaying %0.1lf seconds", 694 (double)delay/1000000); 695 usleep(delay); 696 } 697 explicit_bzero(passwdhash, sizeof(passwdhash)); 698 } else if (!locked && lock) { 699 debug("agent locked"); 700 locked = 1; 701 arc4random_buf(lock_salt, sizeof(lock_salt)); 702 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 703 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 704 fatal("bcrypt_pbkdf"); 705 success = 1; 706 } 707 freezero(passwd, pwlen); 708 send_status(e, success); 709 } 710 711 static void 712 no_identities(SocketEntry *e) 713 { 714 struct sshbuf *msg; 715 int r; 716 717 if ((msg = sshbuf_new()) == NULL) 718 fatal("%s: sshbuf_new failed", __func__); 719 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 720 (r = sshbuf_put_u32(msg, 0)) != 0 || 721 (r = sshbuf_put_stringb(e->output, msg)) != 0) 722 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 723 sshbuf_free(msg); 724 } 725 726 #ifdef ENABLE_PKCS11 727 static void 728 process_add_smartcard_key(SocketEntry *e) 729 { 730 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 731 char **comments = NULL; 732 int r, i, count = 0, success = 0, confirm = 0; 733 u_int seconds; 734 time_t death = 0; 735 u_char type; 736 struct sshkey **keys = NULL, *k; 737 Identity *id; 738 739 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 740 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 741 error("%s: buffer error: %s", __func__, ssh_err(r)); 742 goto send; 743 } 744 745 while (sshbuf_len(e->request)) { 746 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 747 error("%s: buffer error: %s", __func__, ssh_err(r)); 748 goto send; 749 } 750 switch (type) { 751 case SSH_AGENT_CONSTRAIN_LIFETIME: 752 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 753 error("%s: buffer error: %s", 754 __func__, ssh_err(r)); 755 goto send; 756 } 757 death = monotime() + seconds; 758 break; 759 case SSH_AGENT_CONSTRAIN_CONFIRM: 760 confirm = 1; 761 break; 762 default: 763 error("%s: Unknown constraint type %d", __func__, type); 764 goto send; 765 } 766 } 767 if (realpath(provider, canonical_provider) == NULL) { 768 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 769 provider, strerror(errno)); 770 goto send; 771 } 772 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 773 verbose("refusing PKCS#11 add of \"%.100s\": " 774 "provider not allowed", canonical_provider); 775 goto send; 776 } 777 debug("%s: add %.100s", __func__, canonical_provider); 778 if (lifetime && !death) 779 death = monotime() + lifetime; 780 781 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 782 for (i = 0; i < count; i++) { 783 k = keys[i]; 784 if (lookup_identity(k) == NULL) { 785 id = xcalloc(1, sizeof(Identity)); 786 id->key = k; 787 keys[i] = NULL; /* transferred */ 788 id->provider = xstrdup(canonical_provider); 789 if (*comments[i] != '\0') { 790 id->comment = comments[i]; 791 comments[i] = NULL; /* transferred */ 792 } else { 793 id->comment = xstrdup(canonical_provider); 794 } 795 id->death = death; 796 id->confirm = confirm; 797 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 798 idtab->nentries++; 799 success = 1; 800 } 801 sshkey_free(keys[i]); 802 free(comments[i]); 803 } 804 send: 805 free(pin); 806 free(provider); 807 free(keys); 808 free(comments); 809 send_status(e, success); 810 } 811 812 static void 813 process_remove_smartcard_key(SocketEntry *e) 814 { 815 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 816 int r, success = 0; 817 Identity *id, *nxt; 818 819 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 820 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 821 error("%s: buffer error: %s", __func__, ssh_err(r)); 822 goto send; 823 } 824 free(pin); 825 826 if (realpath(provider, canonical_provider) == NULL) { 827 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 828 provider, strerror(errno)); 829 goto send; 830 } 831 832 debug("%s: remove %.100s", __func__, canonical_provider); 833 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 834 nxt = TAILQ_NEXT(id, next); 835 /* Skip file--based keys */ 836 if (id->provider == NULL) 837 continue; 838 if (!strcmp(canonical_provider, id->provider)) { 839 TAILQ_REMOVE(&idtab->idlist, id, next); 840 free_identity(id); 841 idtab->nentries--; 842 } 843 } 844 if (pkcs11_del_provider(canonical_provider) == 0) 845 success = 1; 846 else 847 error("%s: pkcs11_del_provider failed", __func__); 848 send: 849 free(provider); 850 send_status(e, success); 851 } 852 #endif /* ENABLE_PKCS11 */ 853 854 /* dispatch incoming messages */ 855 856 static int 857 process_message(u_int socknum) 858 { 859 u_int msg_len; 860 u_char type; 861 const u_char *cp; 862 int r; 863 SocketEntry *e; 864 865 if (socknum >= sockets_alloc) { 866 fatal("%s: socket number %u >= allocated %u", 867 __func__, socknum, sockets_alloc); 868 } 869 e = &sockets[socknum]; 870 871 if (sshbuf_len(e->input) < 5) 872 return 0; /* Incomplete message header. */ 873 cp = sshbuf_ptr(e->input); 874 msg_len = PEEK_U32(cp); 875 if (msg_len > AGENT_MAX_LEN) { 876 debug("%s: socket %u (fd=%d) message too long %u > %u", 877 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 878 return -1; 879 } 880 if (sshbuf_len(e->input) < msg_len + 4) 881 return 0; /* Incomplete message body. */ 882 883 /* move the current input to e->request */ 884 sshbuf_reset(e->request); 885 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 886 (r = sshbuf_get_u8(e->request, &type)) != 0) { 887 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 888 r == SSH_ERR_STRING_TOO_LARGE) { 889 debug("%s: buffer error: %s", __func__, ssh_err(r)); 890 return -1; 891 } 892 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 893 } 894 895 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 896 897 /* check whether agent is locked */ 898 if (locked && type != SSH_AGENTC_UNLOCK) { 899 sshbuf_reset(e->request); 900 switch (type) { 901 case SSH2_AGENTC_REQUEST_IDENTITIES: 902 /* send empty lists */ 903 no_identities(e); 904 break; 905 default: 906 /* send a fail message for all other request types */ 907 send_status(e, 0); 908 } 909 return 0; 910 } 911 912 switch (type) { 913 case SSH_AGENTC_LOCK: 914 case SSH_AGENTC_UNLOCK: 915 process_lock_agent(e, type == SSH_AGENTC_LOCK); 916 break; 917 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 918 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 919 break; 920 /* ssh2 */ 921 case SSH2_AGENTC_SIGN_REQUEST: 922 process_sign_request2(e); 923 break; 924 case SSH2_AGENTC_REQUEST_IDENTITIES: 925 process_request_identities(e); 926 break; 927 case SSH2_AGENTC_ADD_IDENTITY: 928 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 929 process_add_identity(e); 930 break; 931 case SSH2_AGENTC_REMOVE_IDENTITY: 932 process_remove_identity(e); 933 break; 934 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 935 process_remove_all_identities(e); 936 break; 937 #ifdef ENABLE_PKCS11 938 case SSH_AGENTC_ADD_SMARTCARD_KEY: 939 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 940 process_add_smartcard_key(e); 941 break; 942 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 943 process_remove_smartcard_key(e); 944 break; 945 #endif /* ENABLE_PKCS11 */ 946 default: 947 /* Unknown message. Respond with failure. */ 948 error("Unknown message %d", type); 949 sshbuf_reset(e->request); 950 send_status(e, 0); 951 break; 952 } 953 return 0; 954 } 955 956 static void 957 new_socket(sock_type type, int fd) 958 { 959 u_int i, old_alloc, new_alloc; 960 961 set_nonblock(fd); 962 963 if (fd > max_fd) 964 max_fd = fd; 965 966 for (i = 0; i < sockets_alloc; i++) 967 if (sockets[i].type == AUTH_UNUSED) { 968 sockets[i].fd = fd; 969 if ((sockets[i].input = sshbuf_new()) == NULL) 970 fatal("%s: sshbuf_new failed", __func__); 971 if ((sockets[i].output = sshbuf_new()) == NULL) 972 fatal("%s: sshbuf_new failed", __func__); 973 if ((sockets[i].request = sshbuf_new()) == NULL) 974 fatal("%s: sshbuf_new failed", __func__); 975 sockets[i].type = type; 976 return; 977 } 978 old_alloc = sockets_alloc; 979 new_alloc = sockets_alloc + 10; 980 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 981 for (i = old_alloc; i < new_alloc; i++) 982 sockets[i].type = AUTH_UNUSED; 983 sockets_alloc = new_alloc; 984 sockets[old_alloc].fd = fd; 985 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 986 fatal("%s: sshbuf_new failed", __func__); 987 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 988 fatal("%s: sshbuf_new failed", __func__); 989 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 990 fatal("%s: sshbuf_new failed", __func__); 991 sockets[old_alloc].type = type; 992 } 993 994 static int 995 handle_socket_read(u_int socknum) 996 { 997 struct sockaddr_un sunaddr; 998 socklen_t slen; 999 uid_t euid; 1000 gid_t egid; 1001 int fd; 1002 1003 slen = sizeof(sunaddr); 1004 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1005 if (fd == -1) { 1006 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1007 return -1; 1008 } 1009 if (getpeereid(fd, &euid, &egid) == -1) { 1010 error("getpeereid %d failed: %s", fd, strerror(errno)); 1011 close(fd); 1012 return -1; 1013 } 1014 if ((euid != 0) && (getuid() != euid)) { 1015 error("uid mismatch: peer euid %u != uid %u", 1016 (u_int) euid, (u_int) getuid()); 1017 close(fd); 1018 return -1; 1019 } 1020 new_socket(AUTH_CONNECTION, fd); 1021 return 0; 1022 } 1023 1024 static int 1025 handle_conn_read(u_int socknum) 1026 { 1027 char buf[AGENT_RBUF_LEN]; 1028 ssize_t len; 1029 int r; 1030 1031 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1032 if (len == -1) { 1033 if (errno == EAGAIN || errno == EINTR) 1034 return 0; 1035 error("%s: read error on socket %u (fd %d): %s", 1036 __func__, socknum, sockets[socknum].fd, 1037 strerror(errno)); 1038 } 1039 return -1; 1040 } 1041 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1042 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1043 explicit_bzero(buf, sizeof(buf)); 1044 process_message(socknum); 1045 return 0; 1046 } 1047 1048 static int 1049 handle_conn_write(u_int socknum) 1050 { 1051 ssize_t len; 1052 int r; 1053 1054 if (sshbuf_len(sockets[socknum].output) == 0) 1055 return 0; /* shouldn't happen */ 1056 if ((len = write(sockets[socknum].fd, 1057 sshbuf_ptr(sockets[socknum].output), 1058 sshbuf_len(sockets[socknum].output))) <= 0) { 1059 if (len == -1) { 1060 if (errno == EAGAIN || errno == EINTR) 1061 return 0; 1062 error("%s: read error on socket %u (fd %d): %s", 1063 __func__, socknum, sockets[socknum].fd, 1064 strerror(errno)); 1065 } 1066 return -1; 1067 } 1068 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1069 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1070 return 0; 1071 } 1072 1073 static void 1074 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1075 { 1076 size_t i; 1077 u_int socknum, activefds = npfd; 1078 1079 for (i = 0; i < npfd; i++) { 1080 if (pfd[i].revents == 0) 1081 continue; 1082 /* Find sockets entry */ 1083 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1084 if (sockets[socknum].type != AUTH_SOCKET && 1085 sockets[socknum].type != AUTH_CONNECTION) 1086 continue; 1087 if (pfd[i].fd == sockets[socknum].fd) 1088 break; 1089 } 1090 if (socknum >= sockets_alloc) { 1091 error("%s: no socket for fd %d", __func__, pfd[i].fd); 1092 continue; 1093 } 1094 /* Process events */ 1095 switch (sockets[socknum].type) { 1096 case AUTH_SOCKET: 1097 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1098 break; 1099 if (npfd > maxfds) { 1100 debug3("out of fds (active %u >= limit %u); " 1101 "skipping accept", activefds, maxfds); 1102 break; 1103 } 1104 if (handle_socket_read(socknum) == 0) 1105 activefds++; 1106 break; 1107 case AUTH_CONNECTION: 1108 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1109 handle_conn_read(socknum) != 0) { 1110 goto close_sock; 1111 } 1112 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1113 handle_conn_write(socknum) != 0) { 1114 close_sock: 1115 if (activefds == 0) 1116 fatal("activefds == 0 at close_sock"); 1117 close_socket(&sockets[socknum]); 1118 activefds--; 1119 break; 1120 } 1121 break; 1122 default: 1123 break; 1124 } 1125 } 1126 } 1127 1128 static int 1129 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1130 { 1131 struct pollfd *pfd = *pfdp; 1132 size_t i, j, npfd = 0; 1133 time_t deadline; 1134 int r; 1135 1136 /* Count active sockets */ 1137 for (i = 0; i < sockets_alloc; i++) { 1138 switch (sockets[i].type) { 1139 case AUTH_SOCKET: 1140 case AUTH_CONNECTION: 1141 npfd++; 1142 break; 1143 case AUTH_UNUSED: 1144 break; 1145 default: 1146 fatal("Unknown socket type %d", sockets[i].type); 1147 break; 1148 } 1149 } 1150 if (npfd != *npfdp && 1151 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1152 fatal("%s: recallocarray failed", __func__); 1153 *pfdp = pfd; 1154 *npfdp = npfd; 1155 1156 for (i = j = 0; i < sockets_alloc; i++) { 1157 switch (sockets[i].type) { 1158 case AUTH_SOCKET: 1159 if (npfd > maxfds) { 1160 debug3("out of fds (active %zu >= limit %u); " 1161 "skipping arming listener", npfd, maxfds); 1162 break; 1163 } 1164 pfd[j].fd = sockets[i].fd; 1165 pfd[j].revents = 0; 1166 pfd[j].events = POLLIN; 1167 j++; 1168 break; 1169 case AUTH_CONNECTION: 1170 pfd[j].fd = sockets[i].fd; 1171 pfd[j].revents = 0; 1172 /* 1173 * Only prepare to read if we can handle a full-size 1174 * input read buffer and enqueue a max size reply.. 1175 */ 1176 if ((r = sshbuf_check_reserve(sockets[i].input, 1177 AGENT_RBUF_LEN)) == 0 && 1178 (r = sshbuf_check_reserve(sockets[i].output, 1179 AGENT_MAX_LEN)) == 0) 1180 pfd[j].events = POLLIN; 1181 else if (r != SSH_ERR_NO_BUFFER_SPACE) { 1182 fatal("%s: buffer error: %s", 1183 __func__, ssh_err(r)); 1184 } 1185 if (sshbuf_len(sockets[i].output) > 0) 1186 pfd[j].events |= POLLOUT; 1187 j++; 1188 break; 1189 default: 1190 break; 1191 } 1192 } 1193 deadline = reaper(); 1194 if (parent_alive_interval != 0) 1195 deadline = (deadline == 0) ? parent_alive_interval : 1196 MINIMUM(deadline, parent_alive_interval); 1197 if (deadline == 0) { 1198 *timeoutp = -1; /* INFTIM */ 1199 } else { 1200 if (deadline > INT_MAX / 1000) 1201 *timeoutp = INT_MAX / 1000; 1202 else 1203 *timeoutp = deadline * 1000; 1204 } 1205 return (1); 1206 } 1207 1208 static void 1209 cleanup_socket(void) 1210 { 1211 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1212 return; 1213 debug("%s: cleanup", __func__); 1214 if (socket_name[0]) 1215 unlink(socket_name); 1216 if (socket_dir[0]) 1217 rmdir(socket_dir); 1218 } 1219 1220 void 1221 cleanup_exit(int i) 1222 { 1223 cleanup_socket(); 1224 _exit(i); 1225 } 1226 1227 /*ARGSUSED*/ 1228 static void 1229 cleanup_handler(int sig) 1230 { 1231 cleanup_socket(); 1232 #ifdef ENABLE_PKCS11 1233 pkcs11_terminate(); 1234 #endif 1235 _exit(2); 1236 } 1237 1238 static void 1239 check_parent_exists(void) 1240 { 1241 /* 1242 * If our parent has exited then getppid() will return (pid_t)1, 1243 * so testing for that should be safe. 1244 */ 1245 if (parent_pid != -1 && getppid() != parent_pid) { 1246 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1247 cleanup_socket(); 1248 _exit(2); 1249 } 1250 } 1251 1252 static void 1253 usage(void) 1254 { 1255 fprintf(stderr, 1256 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1257 " [-P allowed_providers] [-t life]\n" 1258 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1259 " [-t life] command [arg ...]\n" 1260 " ssh-agent [-c | -s] -k\n"); 1261 exit(1); 1262 } 1263 1264 int 1265 main(int ac, char **av) 1266 { 1267 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1268 int sock, fd, ch, result, saved_errno; 1269 char *shell, *format, *pidstr, *agentsocket = NULL; 1270 #ifdef HAVE_SETRLIMIT 1271 struct rlimit rlim; 1272 #endif 1273 extern int optind; 1274 extern char *optarg; 1275 pid_t pid; 1276 char pidstrbuf[1 + 3 * sizeof pid]; 1277 size_t len; 1278 mode_t prev_mask; 1279 int timeout = -1; /* INFTIM */ 1280 struct pollfd *pfd = NULL; 1281 size_t npfd = 0; 1282 u_int maxfds; 1283 1284 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1285 sanitise_stdfd(); 1286 1287 /* drop */ 1288 setegid(getgid()); 1289 setgid(getgid()); 1290 1291 platform_disable_tracing(0); /* strict=no */ 1292 1293 #ifdef RLIMIT_NOFILE 1294 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1295 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1296 #endif 1297 1298 __progname = ssh_get_progname(av[0]); 1299 seed_rng(); 1300 1301 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1302 switch (ch) { 1303 case 'E': 1304 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1305 if (fingerprint_hash == -1) 1306 fatal("Invalid hash algorithm \"%s\"", optarg); 1307 break; 1308 case 'c': 1309 if (s_flag) 1310 usage(); 1311 c_flag++; 1312 break; 1313 case 'k': 1314 k_flag++; 1315 break; 1316 case 'O': 1317 if (strcmp(optarg, "no-restrict-websafe") == 0) 1318 restrict_websafe = 0; 1319 else 1320 fatal("Unknown -O option"); 1321 break; 1322 case 'P': 1323 if (allowed_providers != NULL) 1324 fatal("-P option already specified"); 1325 allowed_providers = xstrdup(optarg); 1326 break; 1327 case 's': 1328 if (c_flag) 1329 usage(); 1330 s_flag++; 1331 break; 1332 case 'd': 1333 if (d_flag || D_flag) 1334 usage(); 1335 d_flag++; 1336 break; 1337 case 'D': 1338 if (d_flag || D_flag) 1339 usage(); 1340 D_flag++; 1341 break; 1342 case 'a': 1343 agentsocket = optarg; 1344 break; 1345 case 't': 1346 if ((lifetime = convtime(optarg)) == -1) { 1347 fprintf(stderr, "Invalid lifetime\n"); 1348 usage(); 1349 } 1350 break; 1351 default: 1352 usage(); 1353 } 1354 } 1355 ac -= optind; 1356 av += optind; 1357 1358 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1359 usage(); 1360 1361 if (allowed_providers == NULL) 1362 allowed_providers = xstrdup(DEFAULT_PROVIDER_WHITELIST); 1363 1364 if (ac == 0 && !c_flag && !s_flag) { 1365 shell = getenv("SHELL"); 1366 if (shell != NULL && (len = strlen(shell)) > 2 && 1367 strncmp(shell + len - 3, "csh", 3) == 0) 1368 c_flag = 1; 1369 } 1370 if (k_flag) { 1371 const char *errstr = NULL; 1372 1373 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1374 if (pidstr == NULL) { 1375 fprintf(stderr, "%s not set, cannot kill agent\n", 1376 SSH_AGENTPID_ENV_NAME); 1377 exit(1); 1378 } 1379 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1380 if (errstr) { 1381 fprintf(stderr, 1382 "%s=\"%s\", which is not a good PID: %s\n", 1383 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1384 exit(1); 1385 } 1386 if (kill(pid, SIGTERM) == -1) { 1387 perror("kill"); 1388 exit(1); 1389 } 1390 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1391 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1392 printf(format, SSH_AGENTPID_ENV_NAME); 1393 printf("echo Agent pid %ld killed;\n", (long)pid); 1394 exit(0); 1395 } 1396 1397 /* 1398 * Minimum file descriptors: 1399 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1400 * a few spare for libc / stack protectors / sanitisers, etc. 1401 */ 1402 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1403 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1404 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1405 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1406 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1407 1408 parent_pid = getpid(); 1409 1410 if (agentsocket == NULL) { 1411 /* Create private directory for agent socket */ 1412 mktemp_proto(socket_dir, sizeof(socket_dir)); 1413 if (mkdtemp(socket_dir) == NULL) { 1414 perror("mkdtemp: private socket dir"); 1415 exit(1); 1416 } 1417 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1418 (long)parent_pid); 1419 } else { 1420 /* Try to use specified agent socket */ 1421 socket_dir[0] = '\0'; 1422 strlcpy(socket_name, agentsocket, sizeof socket_name); 1423 } 1424 1425 /* 1426 * Create socket early so it will exist before command gets run from 1427 * the parent. 1428 */ 1429 prev_mask = umask(0177); 1430 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1431 if (sock < 0) { 1432 /* XXX - unix_listener() calls error() not perror() */ 1433 *socket_name = '\0'; /* Don't unlink any existing file */ 1434 cleanup_exit(1); 1435 } 1436 umask(prev_mask); 1437 1438 /* 1439 * Fork, and have the parent execute the command, if any, or present 1440 * the socket data. The child continues as the authentication agent. 1441 */ 1442 if (D_flag || d_flag) { 1443 log_init(__progname, 1444 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1445 SYSLOG_FACILITY_AUTH, 1); 1446 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1447 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1448 SSH_AUTHSOCKET_ENV_NAME); 1449 printf("echo Agent pid %ld;\n", (long)parent_pid); 1450 fflush(stdout); 1451 goto skip; 1452 } 1453 pid = fork(); 1454 if (pid == -1) { 1455 perror("fork"); 1456 cleanup_exit(1); 1457 } 1458 if (pid != 0) { /* Parent - execute the given command. */ 1459 close(sock); 1460 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1461 if (ac == 0) { 1462 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1463 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1464 SSH_AUTHSOCKET_ENV_NAME); 1465 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1466 SSH_AGENTPID_ENV_NAME); 1467 printf("echo Agent pid %ld;\n", (long)pid); 1468 exit(0); 1469 } 1470 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1471 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1472 perror("setenv"); 1473 exit(1); 1474 } 1475 execvp(av[0], av); 1476 perror(av[0]); 1477 exit(1); 1478 } 1479 /* child */ 1480 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1481 1482 if (setsid() == -1) { 1483 error("setsid: %s", strerror(errno)); 1484 cleanup_exit(1); 1485 } 1486 1487 (void)chdir("/"); 1488 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1489 /* XXX might close listen socket */ 1490 (void)dup2(fd, STDIN_FILENO); 1491 (void)dup2(fd, STDOUT_FILENO); 1492 (void)dup2(fd, STDERR_FILENO); 1493 if (fd > 2) 1494 close(fd); 1495 } 1496 1497 #ifdef HAVE_SETRLIMIT 1498 /* deny core dumps, since memory contains unencrypted private keys */ 1499 rlim.rlim_cur = rlim.rlim_max = 0; 1500 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1501 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1502 cleanup_exit(1); 1503 } 1504 #endif 1505 1506 skip: 1507 1508 cleanup_pid = getpid(); 1509 1510 #ifdef ENABLE_PKCS11 1511 pkcs11_init(0); 1512 #endif 1513 new_socket(AUTH_SOCKET, sock); 1514 if (ac > 0) 1515 parent_alive_interval = 10; 1516 idtab_init(); 1517 ssh_signal(SIGPIPE, SIG_IGN); 1518 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1519 ssh_signal(SIGHUP, cleanup_handler); 1520 ssh_signal(SIGTERM, cleanup_handler); 1521 1522 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1523 fatal("%s: pledge: %s", __progname, strerror(errno)); 1524 platform_pledge_agent(); 1525 1526 while (1) { 1527 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1528 result = poll(pfd, npfd, timeout); 1529 saved_errno = errno; 1530 if (parent_alive_interval != 0) 1531 check_parent_exists(); 1532 (void) reaper(); /* remove expired keys */ 1533 if (result == -1) { 1534 if (saved_errno == EINTR) 1535 continue; 1536 fatal("poll: %s", strerror(saved_errno)); 1537 } else if (result > 0) 1538 after_poll(pfd, npfd, maxfds); 1539 } 1540 /* NOTREACHED */ 1541 } 1542