1/* $OpenBSD: ssh-agent.c,v 1.231 2018/05/11 03:38:51 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 "includes.h" 38__RCSID("$FreeBSD$"); 39 40#include <sys/types.h> 41#include <sys/param.h> 42#include <sys/resource.h> 43#include <sys/stat.h> 44#include <sys/socket.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 "sshbuf.h" 81#include "sshkey.h" 82#include "authfd.h" 83#include "compat.h" 84#include "log.h" 85#include "misc.h" 86#include "digest.h" 87#include "ssherr.h" 88#include "match.h" 89 90#ifdef ENABLE_PKCS11 91#include "ssh-pkcs11.h" 92#endif 93 94#ifndef DEFAULT_PKCS11_WHITELIST 95# define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 96#endif 97 98/* Maximum accepted message length */ 99#define AGENT_MAX_LEN (256*1024) 100 101typedef enum { 102 AUTH_UNUSED, 103 AUTH_SOCKET, 104 AUTH_CONNECTION 105} sock_type; 106 107typedef struct { 108 int fd; 109 sock_type type; 110 struct sshbuf *input; 111 struct sshbuf *output; 112 struct sshbuf *request; 113} SocketEntry; 114 115u_int sockets_alloc = 0; 116SocketEntry *sockets = NULL; 117 118typedef struct identity { 119 TAILQ_ENTRY(identity) next; 120 struct sshkey *key; 121 char *comment; 122 char *provider; 123 time_t death; 124 u_int confirm; 125} Identity; 126 127struct idtable { 128 int nentries; 129 TAILQ_HEAD(idqueue, identity) idlist; 130}; 131 132/* private key table */ 133struct idtable *idtab; 134 135int max_fd = 0; 136 137/* pid of shell == parent of agent */ 138pid_t parent_pid = -1; 139time_t parent_alive_interval = 0; 140 141/* pid of process for which cleanup_socket is applicable */ 142pid_t cleanup_pid = 0; 143 144/* pathname and directory for AUTH_SOCKET */ 145char socket_name[PATH_MAX]; 146char socket_dir[PATH_MAX]; 147 148/* PKCS#11 path whitelist */ 149static char *pkcs11_whitelist; 150 151/* locking */ 152#define LOCK_SIZE 32 153#define LOCK_SALT_SIZE 16 154#define LOCK_ROUNDS 1 155int locked = 0; 156u_char lock_pwhash[LOCK_SIZE]; 157u_char lock_salt[LOCK_SALT_SIZE]; 158 159extern char *__progname; 160 161/* Default lifetime in seconds (0 == forever) */ 162static long lifetime = 0; 163 164static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 165 166/* 167 * Client connection count; incremented in new_socket() and decremented in 168 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 169 * normally initialized to 1, it will never reach 0. However, if the -x 170 * option is specified, it is initialized to 0 in main(); in that case, 171 * ssh-agent will exit as soon as it has had at least one client but no 172 * longer has any. 173 */ 174static int xcount = 1; 175 176static void 177close_socket(SocketEntry *e) 178{ 179 int last = 0; 180 181 if (e->type == AUTH_CONNECTION) { 182 debug("xcount %d -> %d", xcount, xcount - 1); 183 if (--xcount == 0) 184 last = 1; 185 } 186 close(e->fd); 187 e->fd = -1; 188 e->type = AUTH_UNUSED; 189 sshbuf_free(e->input); 190 sshbuf_free(e->output); 191 sshbuf_free(e->request); 192 if (last) 193 cleanup_exit(0); 194} 195 196static void 197idtab_init(void) 198{ 199 idtab = xcalloc(1, sizeof(*idtab)); 200 TAILQ_INIT(&idtab->idlist); 201 idtab->nentries = 0; 202} 203 204static void 205free_identity(Identity *id) 206{ 207 sshkey_free(id->key); 208 free(id->provider); 209 free(id->comment); 210 free(id); 211} 212 213/* return matching private key for given public key */ 214static Identity * 215lookup_identity(struct sshkey *key) 216{ 217 Identity *id; 218 219 TAILQ_FOREACH(id, &idtab->idlist, next) { 220 if (sshkey_equal(key, id->key)) 221 return (id); 222 } 223 return (NULL); 224} 225 226/* Check confirmation of keysign request */ 227static int 228confirm_key(Identity *id) 229{ 230 char *p; 231 int ret = -1; 232 233 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 234 if (p != NULL && 235 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 236 id->comment, p)) 237 ret = 0; 238 free(p); 239 240 return (ret); 241} 242 243static void 244send_status(SocketEntry *e, int success) 245{ 246 int r; 247 248 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 249 (r = sshbuf_put_u8(e->output, success ? 250 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 251 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 252} 253 254/* send list of supported public keys to 'client' */ 255static void 256process_request_identities(SocketEntry *e) 257{ 258 Identity *id; 259 struct sshbuf *msg; 260 int r; 261 262 if ((msg = sshbuf_new()) == NULL) 263 fatal("%s: sshbuf_new failed", __func__); 264 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 265 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 266 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 267 TAILQ_FOREACH(id, &idtab->idlist, next) { 268 if ((r = sshkey_puts_opts(id->key, msg, SSHKEY_SERIALIZE_INFO)) 269 != 0 || 270 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 271 error("%s: put key/comment: %s", __func__, 272 ssh_err(r)); 273 continue; 274 } 275 } 276 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 277 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 278 sshbuf_free(msg); 279} 280 281 282static char * 283agent_decode_alg(struct sshkey *key, u_int flags) 284{ 285 if (key->type == KEY_RSA) { 286 if (flags & SSH_AGENT_RSA_SHA2_256) 287 return "rsa-sha2-256"; 288 else if (flags & SSH_AGENT_RSA_SHA2_512) 289 return "rsa-sha2-512"; 290 } 291 return NULL; 292} 293 294/* ssh2 only */ 295static void 296process_sign_request2(SocketEntry *e) 297{ 298 const u_char *data; 299 u_char *signature = NULL; 300 size_t dlen, slen = 0; 301 u_int compat = 0, flags; 302 int r, ok = -1; 303 struct sshbuf *msg; 304 struct sshkey *key = NULL; 305 struct identity *id; 306 307 if ((msg = sshbuf_new()) == NULL) 308 fatal("%s: sshbuf_new failed", __func__); 309 if ((r = sshkey_froms(e->request, &key)) != 0 || 310 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 311 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 312 error("%s: couldn't parse request: %s", __func__, ssh_err(r)); 313 goto send; 314 } 315 316 if ((id = lookup_identity(key)) == NULL) { 317 verbose("%s: %s key not found", __func__, sshkey_type(key)); 318 goto send; 319 } 320 if (id->confirm && confirm_key(id) != 0) { 321 verbose("%s: user refused key", __func__); 322 goto send; 323 } 324 if ((r = sshkey_sign(id->key, &signature, &slen, 325 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 326 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 327 goto send; 328 } 329 /* Success */ 330 ok = 0; 331 send: 332 sshkey_free(key); 333 if (ok == 0) { 334 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 335 (r = sshbuf_put_string(msg, signature, slen)) != 0) 336 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 337 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 338 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 339 340 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 341 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 342 343 sshbuf_free(msg); 344 free(signature); 345} 346 347/* shared */ 348static void 349process_remove_identity(SocketEntry *e) 350{ 351 int r, success = 0; 352 struct sshkey *key = NULL; 353 Identity *id; 354 355 if ((r = sshkey_froms(e->request, &key)) != 0) { 356 error("%s: get key: %s", __func__, ssh_err(r)); 357 goto done; 358 } 359 if ((id = lookup_identity(key)) == NULL) { 360 debug("%s: key not found", __func__); 361 goto done; 362 } 363 /* We have this key, free it. */ 364 if (idtab->nentries < 1) 365 fatal("%s: internal error: nentries %d", 366 __func__, idtab->nentries); 367 TAILQ_REMOVE(&idtab->idlist, id, next); 368 free_identity(id); 369 idtab->nentries--; 370 sshkey_free(key); 371 success = 1; 372 done: 373 send_status(e, success); 374} 375 376static void 377process_remove_all_identities(SocketEntry *e) 378{ 379 Identity *id; 380 381 /* Loop over all identities and clear the keys. */ 382 for (id = TAILQ_FIRST(&idtab->idlist); id; 383 id = TAILQ_FIRST(&idtab->idlist)) { 384 TAILQ_REMOVE(&idtab->idlist, id, next); 385 free_identity(id); 386 } 387 388 /* Mark that there are no identities. */ 389 idtab->nentries = 0; 390 391 /* Send success. */ 392 send_status(e, 1); 393} 394 395/* removes expired keys and returns number of seconds until the next expiry */ 396static time_t 397reaper(void) 398{ 399 time_t deadline = 0, now = monotime(); 400 Identity *id, *nxt; 401 402 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 403 nxt = TAILQ_NEXT(id, next); 404 if (id->death == 0) 405 continue; 406 if (now >= id->death) { 407 debug("expiring key '%s'", id->comment); 408 TAILQ_REMOVE(&idtab->idlist, id, next); 409 free_identity(id); 410 idtab->nentries--; 411 } else 412 deadline = (deadline == 0) ? id->death : 413 MINIMUM(deadline, id->death); 414 } 415 if (deadline == 0 || deadline <= now) 416 return 0; 417 else 418 return (deadline - now); 419} 420 421static void 422process_add_identity(SocketEntry *e) 423{ 424 Identity *id; 425 int success = 0, confirm = 0; 426 u_int seconds, maxsign; 427 char *comment = NULL; 428 time_t death = 0; 429 struct sshkey *k = NULL; 430 u_char ctype; 431 int r = SSH_ERR_INTERNAL_ERROR; 432 433 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 434 k == NULL || 435 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 436 error("%s: decode private key: %s", __func__, ssh_err(r)); 437 goto err; 438 } 439 440 while (sshbuf_len(e->request)) { 441 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 442 error("%s: buffer error: %s", __func__, ssh_err(r)); 443 goto err; 444 } 445 switch (ctype) { 446 case SSH_AGENT_CONSTRAIN_LIFETIME: 447 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 448 error("%s: bad lifetime constraint: %s", 449 __func__, ssh_err(r)); 450 goto err; 451 } 452 death = monotime() + seconds; 453 break; 454 case SSH_AGENT_CONSTRAIN_CONFIRM: 455 confirm = 1; 456 break; 457 case SSH_AGENT_CONSTRAIN_MAXSIGN: 458 if ((r = sshbuf_get_u32(e->request, &maxsign)) != 0) { 459 error("%s: bad maxsign constraint: %s", 460 __func__, ssh_err(r)); 461 goto err; 462 } 463 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 464 error("%s: cannot enable maxsign: %s", 465 __func__, ssh_err(r)); 466 goto err; 467 } 468 break; 469 default: 470 error("%s: Unknown constraint %d", __func__, ctype); 471 err: 472 sshbuf_reset(e->request); 473 free(comment); 474 sshkey_free(k); 475 goto send; 476 } 477 } 478 479 success = 1; 480 if (lifetime && !death) 481 death = monotime() + lifetime; 482 if ((id = lookup_identity(k)) == NULL) { 483 id = xcalloc(1, sizeof(Identity)); 484 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 485 /* Increment the number of identities. */ 486 idtab->nentries++; 487 } else { 488 /* key state might have been updated */ 489 sshkey_free(id->key); 490 free(id->comment); 491 } 492 id->key = k; 493 id->comment = comment; 494 id->death = death; 495 id->confirm = confirm; 496send: 497 send_status(e, success); 498} 499 500/* XXX todo: encrypt sensitive data with passphrase */ 501static void 502process_lock_agent(SocketEntry *e, int lock) 503{ 504 int r, success = 0, delay; 505 char *passwd; 506 u_char passwdhash[LOCK_SIZE]; 507 static u_int fail_count = 0; 508 size_t pwlen; 509 510 /* 511 * This is deliberately fatal: the user has requested that we lock, 512 * but we can't parse their request properly. The only safe thing to 513 * do is abort. 514 */ 515 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 516 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 517 if (pwlen == 0) { 518 debug("empty password not supported"); 519 } else if (locked && !lock) { 520 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 521 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 522 fatal("bcrypt_pbkdf"); 523 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 524 debug("agent unlocked"); 525 locked = 0; 526 fail_count = 0; 527 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 528 success = 1; 529 } else { 530 /* delay in 0.1s increments up to 10s */ 531 if (fail_count < 100) 532 fail_count++; 533 delay = 100000 * fail_count; 534 debug("unlock failed, delaying %0.1lf seconds", 535 (double)delay/1000000); 536 usleep(delay); 537 } 538 explicit_bzero(passwdhash, sizeof(passwdhash)); 539 } else if (!locked && lock) { 540 debug("agent locked"); 541 locked = 1; 542 arc4random_buf(lock_salt, sizeof(lock_salt)); 543 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 544 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 545 fatal("bcrypt_pbkdf"); 546 success = 1; 547 } 548 explicit_bzero(passwd, pwlen); 549 free(passwd); 550 send_status(e, success); 551} 552 553static void 554no_identities(SocketEntry *e) 555{ 556 struct sshbuf *msg; 557 int r; 558 559 if ((msg = sshbuf_new()) == NULL) 560 fatal("%s: sshbuf_new failed", __func__); 561 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 562 (r = sshbuf_put_u32(msg, 0)) != 0 || 563 (r = sshbuf_put_stringb(e->output, msg)) != 0) 564 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 565 sshbuf_free(msg); 566} 567 568#ifdef ENABLE_PKCS11 569static void 570process_add_smartcard_key(SocketEntry *e) 571{ 572 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 573 int r, i, count = 0, success = 0, confirm = 0; 574 u_int seconds; 575 time_t death = 0; 576 u_char type; 577 struct sshkey **keys = NULL, *k; 578 Identity *id; 579 580 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 581 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 582 error("%s: buffer error: %s", __func__, ssh_err(r)); 583 goto send; 584 } 585 586 while (sshbuf_len(e->request)) { 587 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 588 error("%s: buffer error: %s", __func__, ssh_err(r)); 589 goto send; 590 } 591 switch (type) { 592 case SSH_AGENT_CONSTRAIN_LIFETIME: 593 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 594 error("%s: buffer error: %s", 595 __func__, ssh_err(r)); 596 goto send; 597 } 598 death = monotime() + seconds; 599 break; 600 case SSH_AGENT_CONSTRAIN_CONFIRM: 601 confirm = 1; 602 break; 603 default: 604 error("%s: Unknown constraint type %d", __func__, type); 605 goto send; 606 } 607 } 608 if (realpath(provider, canonical_provider) == NULL) { 609 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 610 provider, strerror(errno)); 611 goto send; 612 } 613 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 614 verbose("refusing PKCS#11 add of \"%.100s\": " 615 "provider not whitelisted", canonical_provider); 616 goto send; 617 } 618 debug("%s: add %.100s", __func__, canonical_provider); 619 if (lifetime && !death) 620 death = monotime() + lifetime; 621 622 count = pkcs11_add_provider(canonical_provider, pin, &keys); 623 for (i = 0; i < count; i++) { 624 k = keys[i]; 625 if (lookup_identity(k) == NULL) { 626 id = xcalloc(1, sizeof(Identity)); 627 id->key = k; 628 id->provider = xstrdup(canonical_provider); 629 id->comment = xstrdup(canonical_provider); /* XXX */ 630 id->death = death; 631 id->confirm = confirm; 632 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 633 idtab->nentries++; 634 success = 1; 635 } else { 636 sshkey_free(k); 637 } 638 keys[i] = NULL; 639 } 640send: 641 free(pin); 642 free(provider); 643 free(keys); 644 send_status(e, success); 645} 646 647static void 648process_remove_smartcard_key(SocketEntry *e) 649{ 650 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 651 int r, success = 0; 652 Identity *id, *nxt; 653 654 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 655 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 656 error("%s: buffer error: %s", __func__, ssh_err(r)); 657 goto send; 658 } 659 free(pin); 660 661 if (realpath(provider, canonical_provider) == NULL) { 662 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 663 provider, strerror(errno)); 664 goto send; 665 } 666 667 debug("%s: remove %.100s", __func__, canonical_provider); 668 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 669 nxt = TAILQ_NEXT(id, next); 670 /* Skip file--based keys */ 671 if (id->provider == NULL) 672 continue; 673 if (!strcmp(canonical_provider, id->provider)) { 674 TAILQ_REMOVE(&idtab->idlist, id, next); 675 free_identity(id); 676 idtab->nentries--; 677 } 678 } 679 if (pkcs11_del_provider(canonical_provider) == 0) 680 success = 1; 681 else 682 error("%s: pkcs11_del_provider failed", __func__); 683send: 684 free(provider); 685 send_status(e, success); 686} 687#endif /* ENABLE_PKCS11 */ 688 689/* dispatch incoming messages */ 690 691static int 692process_message(u_int socknum) 693{ 694 u_int msg_len; 695 u_char type; 696 const u_char *cp; 697 int r; 698 SocketEntry *e; 699 700 if (socknum >= sockets_alloc) { 701 fatal("%s: socket number %u >= allocated %u", 702 __func__, socknum, sockets_alloc); 703 } 704 e = &sockets[socknum]; 705 706 if (sshbuf_len(e->input) < 5) 707 return 0; /* Incomplete message header. */ 708 cp = sshbuf_ptr(e->input); 709 msg_len = PEEK_U32(cp); 710 if (msg_len > AGENT_MAX_LEN) { 711 debug("%s: socket %u (fd=%d) message too long %u > %u", 712 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 713 return -1; 714 } 715 if (sshbuf_len(e->input) < msg_len + 4) 716 return 0; /* Incomplete message body. */ 717 718 /* move the current input to e->request */ 719 sshbuf_reset(e->request); 720 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 721 (r = sshbuf_get_u8(e->request, &type)) != 0) { 722 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 723 r == SSH_ERR_STRING_TOO_LARGE) { 724 debug("%s: buffer error: %s", __func__, ssh_err(r)); 725 return -1; 726 } 727 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 728 } 729 730 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 731 732 /* check whether agent is locked */ 733 if (locked && type != SSH_AGENTC_UNLOCK) { 734 sshbuf_reset(e->request); 735 switch (type) { 736 case SSH2_AGENTC_REQUEST_IDENTITIES: 737 /* send empty lists */ 738 no_identities(e); 739 break; 740 default: 741 /* send a fail message for all other request types */ 742 send_status(e, 0); 743 } 744 return 0; 745 } 746 747 switch (type) { 748 case SSH_AGENTC_LOCK: 749 case SSH_AGENTC_UNLOCK: 750 process_lock_agent(e, type == SSH_AGENTC_LOCK); 751 break; 752 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 753 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 754 break; 755 /* ssh2 */ 756 case SSH2_AGENTC_SIGN_REQUEST: 757 process_sign_request2(e); 758 break; 759 case SSH2_AGENTC_REQUEST_IDENTITIES: 760 process_request_identities(e); 761 break; 762 case SSH2_AGENTC_ADD_IDENTITY: 763 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 764 process_add_identity(e); 765 break; 766 case SSH2_AGENTC_REMOVE_IDENTITY: 767 process_remove_identity(e); 768 break; 769 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 770 process_remove_all_identities(e); 771 break; 772#ifdef ENABLE_PKCS11 773 case SSH_AGENTC_ADD_SMARTCARD_KEY: 774 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 775 process_add_smartcard_key(e); 776 break; 777 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 778 process_remove_smartcard_key(e); 779 break; 780#endif /* ENABLE_PKCS11 */ 781 default: 782 /* Unknown message. Respond with failure. */ 783 error("Unknown message %d", type); 784 sshbuf_reset(e->request); 785 send_status(e, 0); 786 break; 787 } 788 return 0; 789} 790 791static void 792new_socket(sock_type type, int fd) 793{ 794 u_int i, old_alloc, new_alloc; 795 796 if (type == AUTH_CONNECTION) { 797 debug("xcount %d -> %d", xcount, xcount + 1); 798 ++xcount; 799 } 800 set_nonblock(fd); 801 802 if (fd > max_fd) 803 max_fd = fd; 804 805 for (i = 0; i < sockets_alloc; i++) 806 if (sockets[i].type == AUTH_UNUSED) { 807 sockets[i].fd = fd; 808 if ((sockets[i].input = sshbuf_new()) == NULL) 809 fatal("%s: sshbuf_new failed", __func__); 810 if ((sockets[i].output = sshbuf_new()) == NULL) 811 fatal("%s: sshbuf_new failed", __func__); 812 if ((sockets[i].request = sshbuf_new()) == NULL) 813 fatal("%s: sshbuf_new failed", __func__); 814 sockets[i].type = type; 815 return; 816 } 817 old_alloc = sockets_alloc; 818 new_alloc = sockets_alloc + 10; 819 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 820 for (i = old_alloc; i < new_alloc; i++) 821 sockets[i].type = AUTH_UNUSED; 822 sockets_alloc = new_alloc; 823 sockets[old_alloc].fd = fd; 824 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 825 fatal("%s: sshbuf_new failed", __func__); 826 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 827 fatal("%s: sshbuf_new failed", __func__); 828 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 829 fatal("%s: sshbuf_new failed", __func__); 830 sockets[old_alloc].type = type; 831} 832 833static int 834handle_socket_read(u_int socknum) 835{ 836 struct sockaddr_un sunaddr; 837 socklen_t slen; 838 uid_t euid; 839 gid_t egid; 840 int fd; 841 842 slen = sizeof(sunaddr); 843 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 844 if (fd < 0) { 845 error("accept from AUTH_SOCKET: %s", strerror(errno)); 846 return -1; 847 } 848 if (getpeereid(fd, &euid, &egid) < 0) { 849 error("getpeereid %d failed: %s", fd, strerror(errno)); 850 close(fd); 851 return -1; 852 } 853 if ((euid != 0) && (getuid() != euid)) { 854 error("uid mismatch: peer euid %u != uid %u", 855 (u_int) euid, (u_int) getuid()); 856 close(fd); 857 return -1; 858 } 859 new_socket(AUTH_CONNECTION, fd); 860 return 0; 861} 862 863static int 864handle_conn_read(u_int socknum) 865{ 866 char buf[1024]; 867 ssize_t len; 868 int r; 869 870 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 871 if (len == -1) { 872 if (errno == EAGAIN || errno == EINTR) 873 return 0; 874 error("%s: read error on socket %u (fd %d): %s", 875 __func__, socknum, sockets[socknum].fd, 876 strerror(errno)); 877 } 878 return -1; 879 } 880 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 881 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 882 explicit_bzero(buf, sizeof(buf)); 883 process_message(socknum); 884 return 0; 885} 886 887static int 888handle_conn_write(u_int socknum) 889{ 890 ssize_t len; 891 int r; 892 893 if (sshbuf_len(sockets[socknum].output) == 0) 894 return 0; /* shouldn't happen */ 895 if ((len = write(sockets[socknum].fd, 896 sshbuf_ptr(sockets[socknum].output), 897 sshbuf_len(sockets[socknum].output))) <= 0) { 898 if (len == -1) { 899 if (errno == EAGAIN || errno == EINTR) 900 return 0; 901 error("%s: read error on socket %u (fd %d): %s", 902 __func__, socknum, sockets[socknum].fd, 903 strerror(errno)); 904 } 905 return -1; 906 } 907 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 908 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 909 return 0; 910} 911 912static void 913after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 914{ 915 size_t i; 916 u_int socknum, activefds = npfd; 917 918 for (i = 0; i < npfd; i++) { 919 if (pfd[i].revents == 0) 920 continue; 921 /* Find sockets entry */ 922 for (socknum = 0; socknum < sockets_alloc; socknum++) { 923 if (sockets[socknum].type != AUTH_SOCKET && 924 sockets[socknum].type != AUTH_CONNECTION) 925 continue; 926 if (pfd[i].fd == sockets[socknum].fd) 927 break; 928 } 929 if (socknum >= sockets_alloc) { 930 error("%s: no socket for fd %d", __func__, pfd[i].fd); 931 continue; 932 } 933 /* Process events */ 934 switch (sockets[socknum].type) { 935 case AUTH_SOCKET: 936 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 937 break; 938 if (npfd > maxfds) { 939 debug3("out of fds (active %u >= limit %u); " 940 "skipping accept", activefds, maxfds); 941 break; 942 } 943 if (handle_socket_read(socknum) == 0) 944 activefds++; 945 break; 946 case AUTH_CONNECTION: 947 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 948 handle_conn_read(socknum) != 0) { 949 goto close_sock; 950 } 951 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 952 handle_conn_write(socknum) != 0) { 953 close_sock: 954 if (activefds == 0) 955 fatal("activefds == 0 at close_sock"); 956 close_socket(&sockets[socknum]); 957 activefds--; 958 break; 959 } 960 break; 961 default: 962 break; 963 } 964 } 965} 966 967static int 968prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 969{ 970 struct pollfd *pfd = *pfdp; 971 size_t i, j, npfd = 0; 972 time_t deadline; 973 974 /* Count active sockets */ 975 for (i = 0; i < sockets_alloc; i++) { 976 switch (sockets[i].type) { 977 case AUTH_SOCKET: 978 case AUTH_CONNECTION: 979 npfd++; 980 break; 981 case AUTH_UNUSED: 982 break; 983 default: 984 fatal("Unknown socket type %d", sockets[i].type); 985 break; 986 } 987 } 988 if (npfd != *npfdp && 989 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 990 fatal("%s: recallocarray failed", __func__); 991 *pfdp = pfd; 992 *npfdp = npfd; 993 994 for (i = j = 0; i < sockets_alloc; i++) { 995 switch (sockets[i].type) { 996 case AUTH_SOCKET: 997 if (npfd > maxfds) { 998 debug3("out of fds (active %zu >= limit %u); " 999 "skipping arming listener", npfd, maxfds); 1000 break; 1001 } 1002 pfd[j].fd = sockets[i].fd; 1003 pfd[j].revents = 0; 1004 pfd[j].events = POLLIN; 1005 j++; 1006 break; 1007 case AUTH_CONNECTION: 1008 pfd[j].fd = sockets[i].fd; 1009 pfd[j].revents = 0; 1010 /* XXX backoff when input buffer full */ 1011 pfd[j].events = POLLIN; 1012 if (sshbuf_len(sockets[i].output) > 0) 1013 pfd[j].events |= POLLOUT; 1014 j++; 1015 break; 1016 default: 1017 break; 1018 } 1019 } 1020 deadline = reaper(); 1021 if (parent_alive_interval != 0) 1022 deadline = (deadline == 0) ? parent_alive_interval : 1023 MINIMUM(deadline, parent_alive_interval); 1024 if (deadline == 0) { 1025 *timeoutp = -1; /* INFTIM */ 1026 } else { 1027 if (deadline > INT_MAX / 1000) 1028 *timeoutp = INT_MAX / 1000; 1029 else 1030 *timeoutp = deadline * 1000; 1031 } 1032 return (1); 1033} 1034 1035static void 1036cleanup_socket(void) 1037{ 1038 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1039 return; 1040 debug("%s: cleanup", __func__); 1041 if (socket_name[0]) 1042 unlink(socket_name); 1043 if (socket_dir[0]) 1044 rmdir(socket_dir); 1045} 1046 1047void 1048cleanup_exit(int i) 1049{ 1050 cleanup_socket(); 1051 _exit(i); 1052} 1053 1054/*ARGSUSED*/ 1055static void 1056cleanup_handler(int sig) 1057{ 1058 cleanup_socket(); 1059#ifdef ENABLE_PKCS11 1060 pkcs11_terminate(); 1061#endif 1062 _exit(2); 1063} 1064 1065static void 1066check_parent_exists(void) 1067{ 1068 /* 1069 * If our parent has exited then getppid() will return (pid_t)1, 1070 * so testing for that should be safe. 1071 */ 1072 if (parent_pid != -1 && getppid() != parent_pid) { 1073 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1074 cleanup_socket(); 1075 _exit(2); 1076 } 1077} 1078 1079static void 1080usage(void) 1081{ 1082 fprintf(stderr, 1083 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 1084 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 1085 " ssh-agent [-c | -s] -k\n"); 1086 exit(1); 1087} 1088 1089int 1090main(int ac, char **av) 1091{ 1092 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1093 int sock, fd, ch, result, saved_errno; 1094 char *shell, *format, *pidstr, *agentsocket = NULL; 1095#ifdef HAVE_SETRLIMIT 1096 struct rlimit rlim; 1097#endif 1098 extern int optind; 1099 extern char *optarg; 1100 pid_t pid; 1101 char pidstrbuf[1 + 3 * sizeof pid]; 1102 size_t len; 1103 mode_t prev_mask; 1104 int timeout = -1; /* INFTIM */ 1105 struct pollfd *pfd = NULL; 1106 size_t npfd = 0; 1107 u_int maxfds; 1108 1109 ssh_malloc_init(); /* must be called before any mallocs */ 1110 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1111 sanitise_stdfd(); 1112 1113 /* drop */ 1114 setegid(getgid()); 1115 setgid(getgid()); 1116 setuid(geteuid()); 1117 1118 platform_disable_tracing(0); /* strict=no */ 1119 1120 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1121 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1122 1123#ifdef WITH_OPENSSL 1124 OpenSSL_add_all_algorithms(); 1125#endif 1126 1127 __progname = ssh_get_progname(av[0]); 1128 seed_rng(); 1129 1130 while ((ch = getopt(ac, av, "cDdksE:a:P:t:x")) != -1) { 1131 switch (ch) { 1132 case 'E': 1133 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1134 if (fingerprint_hash == -1) 1135 fatal("Invalid hash algorithm \"%s\"", optarg); 1136 break; 1137 case 'c': 1138 if (s_flag) 1139 usage(); 1140 c_flag++; 1141 break; 1142 case 'k': 1143 k_flag++; 1144 break; 1145 case 'P': 1146 if (pkcs11_whitelist != NULL) 1147 fatal("-P option already specified"); 1148 pkcs11_whitelist = xstrdup(optarg); 1149 break; 1150 case 's': 1151 if (c_flag) 1152 usage(); 1153 s_flag++; 1154 break; 1155 case 'd': 1156 if (d_flag || D_flag) 1157 usage(); 1158 d_flag++; 1159 break; 1160 case 'D': 1161 if (d_flag || D_flag) 1162 usage(); 1163 D_flag++; 1164 break; 1165 case 'a': 1166 agentsocket = optarg; 1167 break; 1168 case 't': 1169 if ((lifetime = convtime(optarg)) == -1) { 1170 fprintf(stderr, "Invalid lifetime\n"); 1171 usage(); 1172 } 1173 break; 1174 case 'x': 1175 xcount = 0; 1176 break; 1177 default: 1178 usage(); 1179 } 1180 } 1181 ac -= optind; 1182 av += optind; 1183 1184 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1185 usage(); 1186 1187 if (pkcs11_whitelist == NULL) 1188 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1189 1190 if (ac == 0 && !c_flag && !s_flag) { 1191 shell = getenv("SHELL"); 1192 if (shell != NULL && (len = strlen(shell)) > 2 && 1193 strncmp(shell + len - 3, "csh", 3) == 0) 1194 c_flag = 1; 1195 } 1196 if (k_flag) { 1197 const char *errstr = NULL; 1198 1199 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1200 if (pidstr == NULL) { 1201 fprintf(stderr, "%s not set, cannot kill agent\n", 1202 SSH_AGENTPID_ENV_NAME); 1203 exit(1); 1204 } 1205 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1206 if (errstr) { 1207 fprintf(stderr, 1208 "%s=\"%s\", which is not a good PID: %s\n", 1209 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1210 exit(1); 1211 } 1212 if (kill(pid, SIGTERM) == -1) { 1213 perror("kill"); 1214 exit(1); 1215 } 1216 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1217 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1218 printf(format, SSH_AGENTPID_ENV_NAME); 1219 printf("echo Agent pid %ld killed;\n", (long)pid); 1220 exit(0); 1221 } 1222 1223 /* 1224 * Minimum file descriptors: 1225 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1226 * a few spare for libc / stack protectors / sanitisers, etc. 1227 */ 1228#define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1229 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1230 fatal("%s: file descriptior rlimit %lld too low (minimum %u)", 1231 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1232 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1233 1234 parent_pid = getpid(); 1235 1236 if (agentsocket == NULL) { 1237 /* Create private directory for agent socket */ 1238 mktemp_proto(socket_dir, sizeof(socket_dir)); 1239 if (mkdtemp(socket_dir) == NULL) { 1240 perror("mkdtemp: private socket dir"); 1241 exit(1); 1242 } 1243 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1244 (long)parent_pid); 1245 } else { 1246 /* Try to use specified agent socket */ 1247 socket_dir[0] = '\0'; 1248 strlcpy(socket_name, agentsocket, sizeof socket_name); 1249 } 1250 1251 /* 1252 * Create socket early so it will exist before command gets run from 1253 * the parent. 1254 */ 1255 prev_mask = umask(0177); 1256 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1257 if (sock < 0) { 1258 /* XXX - unix_listener() calls error() not perror() */ 1259 *socket_name = '\0'; /* Don't unlink any existing file */ 1260 cleanup_exit(1); 1261 } 1262 umask(prev_mask); 1263 1264 /* 1265 * Fork, and have the parent execute the command, if any, or present 1266 * the socket data. The child continues as the authentication agent. 1267 */ 1268 if (D_flag || d_flag) { 1269 log_init(__progname, 1270 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1271 SYSLOG_FACILITY_AUTH, 1); 1272 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1273 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1274 SSH_AUTHSOCKET_ENV_NAME); 1275 printf("echo Agent pid %ld;\n", (long)parent_pid); 1276 fflush(stdout); 1277 goto skip; 1278 } 1279 pid = fork(); 1280 if (pid == -1) { 1281 perror("fork"); 1282 cleanup_exit(1); 1283 } 1284 if (pid != 0) { /* Parent - execute the given command. */ 1285 close(sock); 1286 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1287 if (ac == 0) { 1288 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1289 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1290 SSH_AUTHSOCKET_ENV_NAME); 1291 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1292 SSH_AGENTPID_ENV_NAME); 1293 printf("echo Agent pid %ld;\n", (long)pid); 1294 exit(0); 1295 } 1296 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1297 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1298 perror("setenv"); 1299 exit(1); 1300 } 1301 execvp(av[0], av); 1302 perror(av[0]); 1303 exit(1); 1304 } 1305 /* child */ 1306 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1307 1308 if (setsid() == -1) { 1309 error("setsid: %s", strerror(errno)); 1310 cleanup_exit(1); 1311 } 1312 1313 (void)chdir("/"); 1314 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1315 /* XXX might close listen socket */ 1316 (void)dup2(fd, STDIN_FILENO); 1317 (void)dup2(fd, STDOUT_FILENO); 1318 (void)dup2(fd, STDERR_FILENO); 1319 if (fd > 2) 1320 close(fd); 1321 } 1322 1323#ifdef HAVE_SETRLIMIT 1324 /* deny core dumps, since memory contains unencrypted private keys */ 1325 rlim.rlim_cur = rlim.rlim_max = 0; 1326 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1327 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1328 cleanup_exit(1); 1329 } 1330#endif 1331 1332skip: 1333 1334 cleanup_pid = getpid(); 1335 1336#ifdef ENABLE_PKCS11 1337 pkcs11_init(0); 1338#endif 1339 new_socket(AUTH_SOCKET, sock); 1340 if (ac > 0) 1341 parent_alive_interval = 10; 1342 idtab_init(); 1343 signal(SIGPIPE, SIG_IGN); 1344 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1345 signal(SIGHUP, cleanup_handler); 1346 signal(SIGTERM, cleanup_handler); 1347 1348 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1349 fatal("%s: pledge: %s", __progname, strerror(errno)); 1350 platform_pledge_agent(); 1351 1352 while (1) { 1353 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1354 result = poll(pfd, npfd, timeout); 1355 saved_errno = errno; 1356 if (parent_alive_interval != 0) 1357 check_parent_exists(); 1358 (void) reaper(); /* remove expired keys */ 1359 if (result < 0) { 1360 if (saved_errno == EINTR) 1361 continue; 1362 fatal("poll: %s", strerror(saved_errno)); 1363 } else if (result > 0) 1364 after_poll(pfd, npfd, maxfds); 1365 } 1366 /* NOTREACHED */ 1367} 1368