1 /* $OpenBSD: ssh-agent.c,v 1.226 2017/11/15 02:10:16 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 45 #ifdef WITH_OPENSSL 46 #include <openssl/evp.h> 47 #endif 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <paths.h> 52 #include <poll.h> 53 #include <signal.h> 54 #include <stdlib.h> 55 #include <stdio.h> 56 #include <string.h> 57 #include <limits.h> 58 #include <time.h> 59 #include <unistd.h> 60 #include <util.h> 61 62 #include "xmalloc.h" 63 #include "ssh.h" 64 #include "sshbuf.h" 65 #include "sshkey.h" 66 #include "authfd.h" 67 #include "compat.h" 68 #include "log.h" 69 #include "misc.h" 70 #include "digest.h" 71 #include "ssherr.h" 72 #include "match.h" 73 74 #ifdef ENABLE_PKCS11 75 #include "ssh-pkcs11.h" 76 #endif 77 78 #ifndef DEFAULT_PKCS11_WHITELIST 79 # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 80 #endif 81 82 /* Maximum accepted message length */ 83 #define AGENT_MAX_LEN (256*1024) 84 85 typedef enum { 86 AUTH_UNUSED, 87 AUTH_SOCKET, 88 AUTH_CONNECTION 89 } sock_type; 90 91 typedef struct { 92 int fd; 93 sock_type type; 94 struct sshbuf *input; 95 struct sshbuf *output; 96 struct sshbuf *request; 97 } SocketEntry; 98 99 u_int sockets_alloc = 0; 100 SocketEntry *sockets = NULL; 101 102 typedef struct identity { 103 TAILQ_ENTRY(identity) next; 104 struct sshkey *key; 105 char *comment; 106 char *provider; 107 time_t death; 108 u_int confirm; 109 } Identity; 110 111 struct idtable { 112 int nentries; 113 TAILQ_HEAD(idqueue, identity) idlist; 114 }; 115 116 /* private key table */ 117 struct idtable *idtab; 118 119 int max_fd = 0; 120 121 /* pid of shell == parent of agent */ 122 pid_t parent_pid = -1; 123 time_t parent_alive_interval = 0; 124 125 /* pid of process for which cleanup_socket is applicable */ 126 pid_t cleanup_pid = 0; 127 128 /* pathname and directory for AUTH_SOCKET */ 129 char socket_name[PATH_MAX]; 130 char socket_dir[PATH_MAX]; 131 132 /* PKCS#11 path whitelist */ 133 static char *pkcs11_whitelist; 134 135 /* locking */ 136 #define LOCK_SIZE 32 137 #define LOCK_SALT_SIZE 16 138 #define LOCK_ROUNDS 1 139 int locked = 0; 140 u_char lock_pwhash[LOCK_SIZE]; 141 u_char lock_salt[LOCK_SALT_SIZE]; 142 143 extern char *__progname; 144 145 /* Default lifetime in seconds (0 == forever) */ 146 static long lifetime = 0; 147 148 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 149 150 static void 151 close_socket(SocketEntry *e) 152 { 153 close(e->fd); 154 e->fd = -1; 155 e->type = AUTH_UNUSED; 156 sshbuf_free(e->input); 157 sshbuf_free(e->output); 158 sshbuf_free(e->request); 159 } 160 161 static void 162 idtab_init(void) 163 { 164 idtab = xcalloc(1, sizeof(*idtab)); 165 TAILQ_INIT(&idtab->idlist); 166 idtab->nentries = 0; 167 } 168 169 static void 170 free_identity(Identity *id) 171 { 172 sshkey_free(id->key); 173 free(id->provider); 174 free(id->comment); 175 free(id); 176 } 177 178 /* return matching private key for given public key */ 179 static Identity * 180 lookup_identity(struct sshkey *key) 181 { 182 Identity *id; 183 184 TAILQ_FOREACH(id, &idtab->idlist, next) { 185 if (sshkey_equal(key, id->key)) 186 return (id); 187 } 188 return (NULL); 189 } 190 191 /* Check confirmation of keysign request */ 192 static int 193 confirm_key(Identity *id) 194 { 195 char *p; 196 int ret = -1; 197 198 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 199 if (p != NULL && 200 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 201 id->comment, p)) 202 ret = 0; 203 free(p); 204 205 return (ret); 206 } 207 208 static void 209 send_status(SocketEntry *e, int success) 210 { 211 int r; 212 213 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 214 (r = sshbuf_put_u8(e->output, success ? 215 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 216 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 217 } 218 219 /* send list of supported public keys to 'client' */ 220 static void 221 process_request_identities(SocketEntry *e) 222 { 223 Identity *id; 224 struct sshbuf *msg; 225 int r; 226 227 if ((msg = sshbuf_new()) == NULL) 228 fatal("%s: sshbuf_new failed", __func__); 229 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 230 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 231 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 232 TAILQ_FOREACH(id, &idtab->idlist, next) { 233 if ((r = sshkey_puts(id->key, msg)) != 0 || 234 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 235 error("%s: put key/comment: %s", __func__, 236 ssh_err(r)); 237 continue; 238 } 239 } 240 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 241 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 242 sshbuf_free(msg); 243 } 244 245 246 static char * 247 agent_decode_alg(struct sshkey *key, u_int flags) 248 { 249 if (key->type == KEY_RSA) { 250 if (flags & SSH_AGENT_RSA_SHA2_256) 251 return "rsa-sha2-256"; 252 else if (flags & SSH_AGENT_RSA_SHA2_512) 253 return "rsa-sha2-512"; 254 } 255 return NULL; 256 } 257 258 /* ssh2 only */ 259 static void 260 process_sign_request2(SocketEntry *e) 261 { 262 const u_char *data; 263 u_char *signature = NULL; 264 size_t dlen, slen = 0; 265 u_int compat = 0, flags; 266 int r, ok = -1; 267 struct sshbuf *msg; 268 struct sshkey *key = NULL; 269 struct identity *id; 270 271 if ((msg = sshbuf_new()) == NULL) 272 fatal("%s: sshbuf_new failed", __func__); 273 if ((r = sshkey_froms(e->request, &key)) != 0 || 274 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 275 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 276 error("%s: couldn't parse request: %s", __func__, ssh_err(r)); 277 goto send; 278 } 279 280 if (flags & SSH_AGENT_OLD_SIGNATURE) 281 compat = SSH_BUG_SIGBLOB; 282 if ((id = lookup_identity(key)) == NULL) { 283 verbose("%s: %s key not found", __func__, sshkey_type(key)); 284 goto send; 285 } 286 if (id->confirm && confirm_key(id) != 0) { 287 verbose("%s: user refused key", __func__); 288 goto send; 289 } 290 if ((r = sshkey_sign(id->key, &signature, &slen, 291 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 292 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 293 goto send; 294 } 295 /* Success */ 296 ok = 0; 297 send: 298 sshkey_free(key); 299 if (ok == 0) { 300 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 301 (r = sshbuf_put_string(msg, signature, slen)) != 0) 302 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 303 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 304 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 305 306 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 307 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 308 309 sshbuf_free(msg); 310 free(signature); 311 } 312 313 /* shared */ 314 static void 315 process_remove_identity(SocketEntry *e) 316 { 317 int r, success = 0; 318 struct sshkey *key = NULL; 319 Identity *id; 320 321 if ((r = sshkey_froms(e->request, &key)) != 0) { 322 error("%s: get key: %s", __func__, ssh_err(r)); 323 goto done; 324 } 325 if ((id = lookup_identity(key)) == NULL) { 326 debug("%s: key not found", __func__); 327 goto done; 328 } 329 /* We have this key, free it. */ 330 if (idtab->nentries < 1) 331 fatal("%s: internal error: nentries %d", 332 __func__, idtab->nentries); 333 TAILQ_REMOVE(&idtab->idlist, id, next); 334 free_identity(id); 335 idtab->nentries--; 336 sshkey_free(key); 337 success = 1; 338 done: 339 send_status(e, success); 340 } 341 342 static void 343 process_remove_all_identities(SocketEntry *e) 344 { 345 Identity *id; 346 347 /* Loop over all identities and clear the keys. */ 348 for (id = TAILQ_FIRST(&idtab->idlist); id; 349 id = TAILQ_FIRST(&idtab->idlist)) { 350 TAILQ_REMOVE(&idtab->idlist, id, next); 351 free_identity(id); 352 } 353 354 /* Mark that there are no identities. */ 355 idtab->nentries = 0; 356 357 /* Send success. */ 358 send_status(e, 1); 359 } 360 361 /* removes expired keys and returns number of seconds until the next expiry */ 362 static time_t 363 reaper(void) 364 { 365 time_t deadline = 0, now = monotime(); 366 Identity *id, *nxt; 367 368 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 369 nxt = TAILQ_NEXT(id, next); 370 if (id->death == 0) 371 continue; 372 if (now >= id->death) { 373 debug("expiring key '%s'", id->comment); 374 TAILQ_REMOVE(&idtab->idlist, id, next); 375 free_identity(id); 376 idtab->nentries--; 377 } else 378 deadline = (deadline == 0) ? id->death : 379 MINIMUM(deadline, id->death); 380 } 381 if (deadline == 0 || deadline <= now) 382 return 0; 383 else 384 return (deadline - now); 385 } 386 387 static void 388 process_add_identity(SocketEntry *e) 389 { 390 Identity *id; 391 int success = 0, confirm = 0; 392 u_int seconds; 393 char *comment = NULL; 394 time_t death = 0; 395 struct sshkey *k = NULL; 396 u_char ctype; 397 int r = SSH_ERR_INTERNAL_ERROR; 398 399 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 400 k == NULL || 401 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 402 error("%s: decode private key: %s", __func__, ssh_err(r)); 403 goto err; 404 } 405 406 while (sshbuf_len(e->request)) { 407 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 408 error("%s: buffer error: %s", __func__, ssh_err(r)); 409 goto err; 410 } 411 switch (ctype) { 412 case SSH_AGENT_CONSTRAIN_LIFETIME: 413 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 414 error("%s: bad lifetime constraint: %s", 415 __func__, ssh_err(r)); 416 goto err; 417 } 418 death = monotime() + seconds; 419 break; 420 case SSH_AGENT_CONSTRAIN_CONFIRM: 421 confirm = 1; 422 break; 423 default: 424 error("%s: Unknown constraint %d", __func__, ctype); 425 err: 426 sshbuf_reset(e->request); 427 free(comment); 428 sshkey_free(k); 429 goto send; 430 } 431 } 432 433 success = 1; 434 if (lifetime && !death) 435 death = monotime() + lifetime; 436 if ((id = lookup_identity(k)) == NULL) { 437 id = xcalloc(1, sizeof(Identity)); 438 id->key = k; 439 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 440 /* Increment the number of identities. */ 441 idtab->nentries++; 442 } else { 443 sshkey_free(k); 444 free(id->comment); 445 } 446 id->comment = comment; 447 id->death = death; 448 id->confirm = confirm; 449 send: 450 send_status(e, success); 451 } 452 453 /* XXX todo: encrypt sensitive data with passphrase */ 454 static void 455 process_lock_agent(SocketEntry *e, int lock) 456 { 457 int r, success = 0, delay; 458 char *passwd; 459 u_char passwdhash[LOCK_SIZE]; 460 static u_int fail_count = 0; 461 size_t pwlen; 462 463 /* 464 * This is deliberately fatal: the user has requested that we lock, 465 * but we can't parse their request properly. The only safe thing to 466 * do is abort. 467 */ 468 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 469 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 470 if (pwlen == 0) { 471 debug("empty password not supported"); 472 } else if (locked && !lock) { 473 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 474 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 475 fatal("bcrypt_pbkdf"); 476 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 477 debug("agent unlocked"); 478 locked = 0; 479 fail_count = 0; 480 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 481 success = 1; 482 } else { 483 /* delay in 0.1s increments up to 10s */ 484 if (fail_count < 100) 485 fail_count++; 486 delay = 100000 * fail_count; 487 debug("unlock failed, delaying %0.1lf seconds", 488 (double)delay/1000000); 489 usleep(delay); 490 } 491 explicit_bzero(passwdhash, sizeof(passwdhash)); 492 } else if (!locked && lock) { 493 debug("agent locked"); 494 locked = 1; 495 arc4random_buf(lock_salt, sizeof(lock_salt)); 496 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 497 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 498 fatal("bcrypt_pbkdf"); 499 success = 1; 500 } 501 explicit_bzero(passwd, pwlen); 502 free(passwd); 503 send_status(e, success); 504 } 505 506 static void 507 no_identities(SocketEntry *e) 508 { 509 struct sshbuf *msg; 510 int r; 511 512 if ((msg = sshbuf_new()) == NULL) 513 fatal("%s: sshbuf_new failed", __func__); 514 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 515 (r = sshbuf_put_u32(msg, 0)) != 0 || 516 (r = sshbuf_put_stringb(e->output, msg)) != 0) 517 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 518 sshbuf_free(msg); 519 } 520 521 #ifdef ENABLE_PKCS11 522 static void 523 process_add_smartcard_key(SocketEntry *e) 524 { 525 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 526 int r, i, count = 0, success = 0, confirm = 0; 527 u_int seconds; 528 time_t death = 0; 529 u_char type; 530 struct sshkey **keys = NULL, *k; 531 Identity *id; 532 533 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 534 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 535 error("%s: buffer error: %s", __func__, ssh_err(r)); 536 goto send; 537 } 538 539 while (sshbuf_len(e->request)) { 540 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 541 error("%s: buffer error: %s", __func__, ssh_err(r)); 542 goto send; 543 } 544 switch (type) { 545 case SSH_AGENT_CONSTRAIN_LIFETIME: 546 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 547 error("%s: buffer error: %s", 548 __func__, ssh_err(r)); 549 goto send; 550 } 551 death = monotime() + seconds; 552 break; 553 case SSH_AGENT_CONSTRAIN_CONFIRM: 554 confirm = 1; 555 break; 556 default: 557 error("%s: Unknown constraint type %d", __func__, type); 558 goto send; 559 } 560 } 561 if (realpath(provider, canonical_provider) == NULL) { 562 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 563 provider, strerror(errno)); 564 goto send; 565 } 566 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 567 verbose("refusing PKCS#11 add of \"%.100s\": " 568 "provider not whitelisted", canonical_provider); 569 goto send; 570 } 571 debug("%s: add %.100s", __func__, canonical_provider); 572 if (lifetime && !death) 573 death = monotime() + lifetime; 574 575 count = pkcs11_add_provider(canonical_provider, pin, &keys); 576 for (i = 0; i < count; i++) { 577 k = keys[i]; 578 if (lookup_identity(k) == NULL) { 579 id = xcalloc(1, sizeof(Identity)); 580 id->key = k; 581 id->provider = xstrdup(canonical_provider); 582 id->comment = xstrdup(canonical_provider); /* XXX */ 583 id->death = death; 584 id->confirm = confirm; 585 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 586 idtab->nentries++; 587 success = 1; 588 } else { 589 sshkey_free(k); 590 } 591 keys[i] = NULL; 592 } 593 send: 594 free(pin); 595 free(provider); 596 free(keys); 597 send_status(e, success); 598 } 599 600 static void 601 process_remove_smartcard_key(SocketEntry *e) 602 { 603 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 604 int r, success = 0; 605 Identity *id, *nxt; 606 607 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 608 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 609 error("%s: buffer error: %s", __func__, ssh_err(r)); 610 goto send; 611 } 612 free(pin); 613 614 if (realpath(provider, canonical_provider) == NULL) { 615 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 616 provider, strerror(errno)); 617 goto send; 618 } 619 620 debug("%s: remove %.100s", __func__, canonical_provider); 621 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 622 nxt = TAILQ_NEXT(id, next); 623 /* Skip file--based keys */ 624 if (id->provider == NULL) 625 continue; 626 if (!strcmp(canonical_provider, id->provider)) { 627 TAILQ_REMOVE(&idtab->idlist, id, next); 628 free_identity(id); 629 idtab->nentries--; 630 } 631 } 632 if (pkcs11_del_provider(canonical_provider) == 0) 633 success = 1; 634 else 635 error("%s: pkcs11_del_provider failed", __func__); 636 send: 637 free(provider); 638 send_status(e, success); 639 } 640 #endif /* ENABLE_PKCS11 */ 641 642 /* dispatch incoming messages */ 643 644 static int 645 process_message(u_int socknum) 646 { 647 u_int msg_len; 648 u_char type; 649 const u_char *cp; 650 int r; 651 SocketEntry *e; 652 653 if (socknum >= sockets_alloc) { 654 fatal("%s: socket number %u >= allocated %u", 655 __func__, socknum, sockets_alloc); 656 } 657 e = &sockets[socknum]; 658 659 if (sshbuf_len(e->input) < 5) 660 return 0; /* Incomplete message header. */ 661 cp = sshbuf_ptr(e->input); 662 msg_len = PEEK_U32(cp); 663 if (msg_len > AGENT_MAX_LEN) { 664 debug("%s: socket %u (fd=%d) message too long %u > %u", 665 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 666 return -1; 667 } 668 if (sshbuf_len(e->input) < msg_len + 4) 669 return 0; /* Incomplete message body. */ 670 671 /* move the current input to e->request */ 672 sshbuf_reset(e->request); 673 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 674 (r = sshbuf_get_u8(e->request, &type)) != 0) { 675 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 676 r == SSH_ERR_STRING_TOO_LARGE) { 677 debug("%s: buffer error: %s", __func__, ssh_err(r)); 678 return -1; 679 } 680 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 681 } 682 683 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 684 685 /* check wheter agent is locked */ 686 if (locked && type != SSH_AGENTC_UNLOCK) { 687 sshbuf_reset(e->request); 688 switch (type) { 689 case SSH2_AGENTC_REQUEST_IDENTITIES: 690 /* send empty lists */ 691 no_identities(e); 692 break; 693 default: 694 /* send a fail message for all other request types */ 695 send_status(e, 0); 696 } 697 return 0; 698 } 699 700 switch (type) { 701 case SSH_AGENTC_LOCK: 702 case SSH_AGENTC_UNLOCK: 703 process_lock_agent(e, type == SSH_AGENTC_LOCK); 704 break; 705 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 706 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 707 break; 708 /* ssh2 */ 709 case SSH2_AGENTC_SIGN_REQUEST: 710 process_sign_request2(e); 711 break; 712 case SSH2_AGENTC_REQUEST_IDENTITIES: 713 process_request_identities(e); 714 break; 715 case SSH2_AGENTC_ADD_IDENTITY: 716 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 717 process_add_identity(e); 718 break; 719 case SSH2_AGENTC_REMOVE_IDENTITY: 720 process_remove_identity(e); 721 break; 722 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 723 process_remove_all_identities(e); 724 break; 725 #ifdef ENABLE_PKCS11 726 case SSH_AGENTC_ADD_SMARTCARD_KEY: 727 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 728 process_add_smartcard_key(e); 729 break; 730 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 731 process_remove_smartcard_key(e); 732 break; 733 #endif /* ENABLE_PKCS11 */ 734 default: 735 /* Unknown message. Respond with failure. */ 736 error("Unknown message %d", type); 737 sshbuf_reset(e->request); 738 send_status(e, 0); 739 break; 740 } 741 return 0; 742 } 743 744 static void 745 new_socket(sock_type type, int fd) 746 { 747 u_int i, old_alloc, new_alloc; 748 749 set_nonblock(fd); 750 751 if (fd > max_fd) 752 max_fd = fd; 753 754 for (i = 0; i < sockets_alloc; i++) 755 if (sockets[i].type == AUTH_UNUSED) { 756 sockets[i].fd = fd; 757 if ((sockets[i].input = sshbuf_new()) == NULL) 758 fatal("%s: sshbuf_new failed", __func__); 759 if ((sockets[i].output = sshbuf_new()) == NULL) 760 fatal("%s: sshbuf_new failed", __func__); 761 if ((sockets[i].request = sshbuf_new()) == NULL) 762 fatal("%s: sshbuf_new failed", __func__); 763 sockets[i].type = type; 764 return; 765 } 766 old_alloc = sockets_alloc; 767 new_alloc = sockets_alloc + 10; 768 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 769 for (i = old_alloc; i < new_alloc; i++) 770 sockets[i].type = AUTH_UNUSED; 771 sockets_alloc = new_alloc; 772 sockets[old_alloc].fd = fd; 773 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 774 fatal("%s: sshbuf_new failed", __func__); 775 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 776 fatal("%s: sshbuf_new failed", __func__); 777 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 778 fatal("%s: sshbuf_new failed", __func__); 779 sockets[old_alloc].type = type; 780 } 781 782 static int 783 handle_socket_read(u_int socknum) 784 { 785 struct sockaddr_un sunaddr; 786 socklen_t slen; 787 uid_t euid; 788 gid_t egid; 789 int fd; 790 791 slen = sizeof(sunaddr); 792 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 793 if (fd < 0) { 794 error("accept from AUTH_SOCKET: %s", strerror(errno)); 795 return -1; 796 } 797 if (getpeereid(fd, &euid, &egid) < 0) { 798 error("getpeereid %d failed: %s", fd, strerror(errno)); 799 close(fd); 800 return -1; 801 } 802 if ((euid != 0) && (getuid() != euid)) { 803 error("uid mismatch: peer euid %u != uid %u", 804 (u_int) euid, (u_int) getuid()); 805 close(fd); 806 return -1; 807 } 808 new_socket(AUTH_CONNECTION, fd); 809 return 0; 810 } 811 812 static int 813 handle_conn_read(u_int socknum) 814 { 815 char buf[1024]; 816 ssize_t len; 817 int r; 818 819 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 820 if (len == -1) { 821 if (errno == EAGAIN || errno == EINTR) 822 return 0; 823 error("%s: read error on socket %u (fd %d): %s", 824 __func__, socknum, sockets[socknum].fd, 825 strerror(errno)); 826 } 827 return -1; 828 } 829 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 830 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 831 explicit_bzero(buf, sizeof(buf)); 832 process_message(socknum); 833 return 0; 834 } 835 836 static int 837 handle_conn_write(u_int socknum) 838 { 839 ssize_t len; 840 int r; 841 842 if (sshbuf_len(sockets[socknum].output) == 0) 843 return 0; /* shouldn't happen */ 844 if ((len = write(sockets[socknum].fd, 845 sshbuf_ptr(sockets[socknum].output), 846 sshbuf_len(sockets[socknum].output))) <= 0) { 847 if (len == -1) { 848 if (errno == EAGAIN || errno == EINTR) 849 return 0; 850 error("%s: read error on socket %u (fd %d): %s", 851 __func__, socknum, sockets[socknum].fd, 852 strerror(errno)); 853 } 854 return -1; 855 } 856 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 857 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 858 return 0; 859 } 860 861 static void 862 after_poll(struct pollfd *pfd, size_t npfd) 863 { 864 size_t i; 865 u_int socknum; 866 867 for (i = 0; i < npfd; i++) { 868 if (pfd[i].revents == 0) 869 continue; 870 /* Find sockets entry */ 871 for (socknum = 0; socknum < sockets_alloc; socknum++) { 872 if (sockets[socknum].type != AUTH_SOCKET && 873 sockets[socknum].type != AUTH_CONNECTION) 874 continue; 875 if (pfd[i].fd == sockets[socknum].fd) 876 break; 877 } 878 if (socknum >= sockets_alloc) { 879 error("%s: no socket for fd %d", __func__, pfd[i].fd); 880 continue; 881 } 882 /* Process events */ 883 switch (sockets[socknum].type) { 884 case AUTH_SOCKET: 885 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 886 handle_socket_read(socknum) != 0) 887 close_socket(&sockets[socknum]); 888 break; 889 case AUTH_CONNECTION: 890 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 891 handle_conn_read(socknum) != 0) { 892 close_socket(&sockets[socknum]); 893 break; 894 } 895 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 896 handle_conn_write(socknum) != 0) 897 close_socket(&sockets[socknum]); 898 break; 899 default: 900 break; 901 } 902 } 903 } 904 905 static int 906 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp) 907 { 908 struct pollfd *pfd = *pfdp; 909 size_t i, j, npfd = 0; 910 time_t deadline; 911 912 /* Count active sockets */ 913 for (i = 0; i < sockets_alloc; i++) { 914 switch (sockets[i].type) { 915 case AUTH_SOCKET: 916 case AUTH_CONNECTION: 917 npfd++; 918 break; 919 case AUTH_UNUSED: 920 break; 921 default: 922 fatal("Unknown socket type %d", sockets[i].type); 923 break; 924 } 925 } 926 if (npfd != *npfdp && 927 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 928 fatal("%s: recallocarray failed", __func__); 929 *pfdp = pfd; 930 *npfdp = npfd; 931 932 for (i = j = 0; i < sockets_alloc; i++) { 933 switch (sockets[i].type) { 934 case AUTH_SOCKET: 935 case AUTH_CONNECTION: 936 pfd[j].fd = sockets[i].fd; 937 pfd[j].revents = 0; 938 /* XXX backoff when input buffer full */ 939 pfd[j].events = POLLIN; 940 if (sshbuf_len(sockets[i].output) > 0) 941 pfd[j].events |= POLLOUT; 942 j++; 943 break; 944 default: 945 break; 946 } 947 } 948 deadline = reaper(); 949 if (parent_alive_interval != 0) 950 deadline = (deadline == 0) ? parent_alive_interval : 951 MINIMUM(deadline, parent_alive_interval); 952 if (deadline == 0) { 953 *timeoutp = -1; /* INFTIM */ 954 } else { 955 if (deadline > INT_MAX / 1000) 956 *timeoutp = INT_MAX / 1000; 957 else 958 *timeoutp = deadline * 1000; 959 } 960 return (1); 961 } 962 963 static void 964 cleanup_socket(void) 965 { 966 if (cleanup_pid != 0 && getpid() != cleanup_pid) 967 return; 968 debug("%s: cleanup", __func__); 969 if (socket_name[0]) 970 unlink(socket_name); 971 if (socket_dir[0]) 972 rmdir(socket_dir); 973 } 974 975 void 976 cleanup_exit(int i) 977 { 978 cleanup_socket(); 979 _exit(i); 980 } 981 982 /*ARGSUSED*/ 983 static void 984 cleanup_handler(int sig) 985 { 986 cleanup_socket(); 987 #ifdef ENABLE_PKCS11 988 pkcs11_terminate(); 989 #endif 990 _exit(2); 991 } 992 993 static void 994 check_parent_exists(void) 995 { 996 /* 997 * If our parent has exited then getppid() will return (pid_t)1, 998 * so testing for that should be safe. 999 */ 1000 if (parent_pid != -1 && getppid() != parent_pid) { 1001 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1002 cleanup_socket(); 1003 _exit(2); 1004 } 1005 } 1006 1007 static void 1008 usage(void) 1009 { 1010 fprintf(stderr, 1011 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1012 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 1013 " ssh-agent [-c | -s] -k\n"); 1014 exit(1); 1015 } 1016 1017 int 1018 main(int ac, char **av) 1019 { 1020 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1021 int sock, fd, ch, result, saved_errno; 1022 char *shell, *format, *pidstr, *agentsocket = NULL; 1023 struct rlimit rlim; 1024 extern int optind; 1025 extern char *optarg; 1026 pid_t pid; 1027 char pidstrbuf[1 + 3 * sizeof pid]; 1028 size_t len; 1029 mode_t prev_mask; 1030 int timeout = -1; /* INFTIM */ 1031 struct pollfd *pfd = NULL; 1032 size_t npfd = 0; 1033 1034 ssh_malloc_init(); /* must be called before any mallocs */ 1035 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1036 sanitise_stdfd(); 1037 1038 /* drop */ 1039 setegid(getgid()); 1040 setgid(getgid()); 1041 1042 #ifdef WITH_OPENSSL 1043 OpenSSL_add_all_algorithms(); 1044 #endif 1045 1046 while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) { 1047 switch (ch) { 1048 case 'E': 1049 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1050 if (fingerprint_hash == -1) 1051 fatal("Invalid hash algorithm \"%s\"", optarg); 1052 break; 1053 case 'c': 1054 if (s_flag) 1055 usage(); 1056 c_flag++; 1057 break; 1058 case 'k': 1059 k_flag++; 1060 break; 1061 case 'P': 1062 if (pkcs11_whitelist != NULL) 1063 fatal("-P option already specified"); 1064 pkcs11_whitelist = xstrdup(optarg); 1065 break; 1066 case 's': 1067 if (c_flag) 1068 usage(); 1069 s_flag++; 1070 break; 1071 case 'd': 1072 if (d_flag || D_flag) 1073 usage(); 1074 d_flag++; 1075 break; 1076 case 'D': 1077 if (d_flag || D_flag) 1078 usage(); 1079 D_flag++; 1080 break; 1081 case 'a': 1082 agentsocket = optarg; 1083 break; 1084 case 't': 1085 if ((lifetime = convtime(optarg)) == -1) { 1086 fprintf(stderr, "Invalid lifetime\n"); 1087 usage(); 1088 } 1089 break; 1090 default: 1091 usage(); 1092 } 1093 } 1094 ac -= optind; 1095 av += optind; 1096 1097 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1098 usage(); 1099 1100 if (pkcs11_whitelist == NULL) 1101 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1102 1103 if (ac == 0 && !c_flag && !s_flag) { 1104 shell = getenv("SHELL"); 1105 if (shell != NULL && (len = strlen(shell)) > 2 && 1106 strncmp(shell + len - 3, "csh", 3) == 0) 1107 c_flag = 1; 1108 } 1109 if (k_flag) { 1110 const char *errstr = NULL; 1111 1112 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1113 if (pidstr == NULL) { 1114 fprintf(stderr, "%s not set, cannot kill agent\n", 1115 SSH_AGENTPID_ENV_NAME); 1116 exit(1); 1117 } 1118 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1119 if (errstr) { 1120 fprintf(stderr, 1121 "%s=\"%s\", which is not a good PID: %s\n", 1122 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1123 exit(1); 1124 } 1125 if (kill(pid, SIGTERM) == -1) { 1126 perror("kill"); 1127 exit(1); 1128 } 1129 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1130 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1131 printf(format, SSH_AGENTPID_ENV_NAME); 1132 printf("echo Agent pid %ld killed;\n", (long)pid); 1133 exit(0); 1134 } 1135 parent_pid = getpid(); 1136 1137 if (agentsocket == NULL) { 1138 /* Create private directory for agent socket */ 1139 mktemp_proto(socket_dir, sizeof(socket_dir)); 1140 if (mkdtemp(socket_dir) == NULL) { 1141 perror("mkdtemp: private socket dir"); 1142 exit(1); 1143 } 1144 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1145 (long)parent_pid); 1146 } else { 1147 /* Try to use specified agent socket */ 1148 socket_dir[0] = '\0'; 1149 strlcpy(socket_name, agentsocket, sizeof socket_name); 1150 } 1151 1152 /* 1153 * Create socket early so it will exist before command gets run from 1154 * the parent. 1155 */ 1156 prev_mask = umask(0177); 1157 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1158 if (sock < 0) { 1159 /* XXX - unix_listener() calls error() not perror() */ 1160 *socket_name = '\0'; /* Don't unlink any existing file */ 1161 cleanup_exit(1); 1162 } 1163 umask(prev_mask); 1164 1165 /* 1166 * Fork, and have the parent execute the command, if any, or present 1167 * the socket data. The child continues as the authentication agent. 1168 */ 1169 if (D_flag || d_flag) { 1170 log_init(__progname, 1171 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1172 SYSLOG_FACILITY_AUTH, 1); 1173 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1174 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1175 SSH_AUTHSOCKET_ENV_NAME); 1176 printf("echo Agent pid %ld;\n", (long)parent_pid); 1177 fflush(stdout); 1178 goto skip; 1179 } 1180 pid = fork(); 1181 if (pid == -1) { 1182 perror("fork"); 1183 cleanup_exit(1); 1184 } 1185 if (pid != 0) { /* Parent - execute the given command. */ 1186 close(sock); 1187 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1188 if (ac == 0) { 1189 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1190 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1191 SSH_AUTHSOCKET_ENV_NAME); 1192 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1193 SSH_AGENTPID_ENV_NAME); 1194 printf("echo Agent pid %ld;\n", (long)pid); 1195 exit(0); 1196 } 1197 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1198 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1199 perror("setenv"); 1200 exit(1); 1201 } 1202 execvp(av[0], av); 1203 perror(av[0]); 1204 exit(1); 1205 } 1206 /* child */ 1207 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1208 1209 if (setsid() == -1) { 1210 error("setsid: %s", strerror(errno)); 1211 cleanup_exit(1); 1212 } 1213 1214 (void)chdir("/"); 1215 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1216 /* XXX might close listen socket */ 1217 (void)dup2(fd, STDIN_FILENO); 1218 (void)dup2(fd, STDOUT_FILENO); 1219 (void)dup2(fd, STDERR_FILENO); 1220 if (fd > 2) 1221 close(fd); 1222 } 1223 1224 /* deny core dumps, since memory contains unencrypted private keys */ 1225 rlim.rlim_cur = rlim.rlim_max = 0; 1226 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1227 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1228 cleanup_exit(1); 1229 } 1230 1231 skip: 1232 1233 cleanup_pid = getpid(); 1234 1235 #ifdef ENABLE_PKCS11 1236 pkcs11_init(0); 1237 #endif 1238 new_socket(AUTH_SOCKET, sock); 1239 if (ac > 0) 1240 parent_alive_interval = 10; 1241 idtab_init(); 1242 signal(SIGPIPE, SIG_IGN); 1243 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1244 signal(SIGHUP, cleanup_handler); 1245 signal(SIGTERM, cleanup_handler); 1246 1247 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1248 fatal("%s: pledge: %s", __progname, strerror(errno)); 1249 1250 while (1) { 1251 prepare_poll(&pfd, &npfd, &timeout); 1252 result = poll(pfd, npfd, timeout); 1253 saved_errno = errno; 1254 if (parent_alive_interval != 0) 1255 check_parent_exists(); 1256 (void) reaper(); /* remove expired keys */ 1257 if (result < 0) { 1258 if (saved_errno == EINTR) 1259 continue; 1260 fatal("poll: %s", strerror(saved_errno)); 1261 } else if (result > 0) 1262 after_poll(pfd, npfd); 1263 } 1264 /* NOTREACHED */ 1265 } 1266