1 /* $OpenBSD: ssh-agent.c,v 1.227 2018/01/23 05:27:21 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 ((id = lookup_identity(key)) == NULL) { 281 verbose("%s: %s key not found", __func__, sshkey_type(key)); 282 goto send; 283 } 284 if (id->confirm && confirm_key(id) != 0) { 285 verbose("%s: user refused key", __func__); 286 goto send; 287 } 288 if ((r = sshkey_sign(id->key, &signature, &slen, 289 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 290 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 291 goto send; 292 } 293 /* Success */ 294 ok = 0; 295 send: 296 sshkey_free(key); 297 if (ok == 0) { 298 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 299 (r = sshbuf_put_string(msg, signature, slen)) != 0) 300 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 301 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 302 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 303 304 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 305 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 306 307 sshbuf_free(msg); 308 free(signature); 309 } 310 311 /* shared */ 312 static void 313 process_remove_identity(SocketEntry *e) 314 { 315 int r, success = 0; 316 struct sshkey *key = NULL; 317 Identity *id; 318 319 if ((r = sshkey_froms(e->request, &key)) != 0) { 320 error("%s: get key: %s", __func__, ssh_err(r)); 321 goto done; 322 } 323 if ((id = lookup_identity(key)) == NULL) { 324 debug("%s: key not found", __func__); 325 goto done; 326 } 327 /* We have this key, free it. */ 328 if (idtab->nentries < 1) 329 fatal("%s: internal error: nentries %d", 330 __func__, idtab->nentries); 331 TAILQ_REMOVE(&idtab->idlist, id, next); 332 free_identity(id); 333 idtab->nentries--; 334 sshkey_free(key); 335 success = 1; 336 done: 337 send_status(e, success); 338 } 339 340 static void 341 process_remove_all_identities(SocketEntry *e) 342 { 343 Identity *id; 344 345 /* Loop over all identities and clear the keys. */ 346 for (id = TAILQ_FIRST(&idtab->idlist); id; 347 id = TAILQ_FIRST(&idtab->idlist)) { 348 TAILQ_REMOVE(&idtab->idlist, id, next); 349 free_identity(id); 350 } 351 352 /* Mark that there are no identities. */ 353 idtab->nentries = 0; 354 355 /* Send success. */ 356 send_status(e, 1); 357 } 358 359 /* removes expired keys and returns number of seconds until the next expiry */ 360 static time_t 361 reaper(void) 362 { 363 time_t deadline = 0, now = monotime(); 364 Identity *id, *nxt; 365 366 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 367 nxt = TAILQ_NEXT(id, next); 368 if (id->death == 0) 369 continue; 370 if (now >= id->death) { 371 debug("expiring key '%s'", id->comment); 372 TAILQ_REMOVE(&idtab->idlist, id, next); 373 free_identity(id); 374 idtab->nentries--; 375 } else 376 deadline = (deadline == 0) ? id->death : 377 MINIMUM(deadline, id->death); 378 } 379 if (deadline == 0 || deadline <= now) 380 return 0; 381 else 382 return (deadline - now); 383 } 384 385 static void 386 process_add_identity(SocketEntry *e) 387 { 388 Identity *id; 389 int success = 0, confirm = 0; 390 u_int seconds; 391 char *comment = NULL; 392 time_t death = 0; 393 struct sshkey *k = NULL; 394 u_char ctype; 395 int r = SSH_ERR_INTERNAL_ERROR; 396 397 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 398 k == NULL || 399 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 400 error("%s: decode private key: %s", __func__, ssh_err(r)); 401 goto err; 402 } 403 404 while (sshbuf_len(e->request)) { 405 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 406 error("%s: buffer error: %s", __func__, ssh_err(r)); 407 goto err; 408 } 409 switch (ctype) { 410 case SSH_AGENT_CONSTRAIN_LIFETIME: 411 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 412 error("%s: bad lifetime constraint: %s", 413 __func__, ssh_err(r)); 414 goto err; 415 } 416 death = monotime() + seconds; 417 break; 418 case SSH_AGENT_CONSTRAIN_CONFIRM: 419 confirm = 1; 420 break; 421 default: 422 error("%s: Unknown constraint %d", __func__, ctype); 423 err: 424 sshbuf_reset(e->request); 425 free(comment); 426 sshkey_free(k); 427 goto send; 428 } 429 } 430 431 success = 1; 432 if (lifetime && !death) 433 death = monotime() + lifetime; 434 if ((id = lookup_identity(k)) == NULL) { 435 id = xcalloc(1, sizeof(Identity)); 436 id->key = k; 437 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 438 /* Increment the number of identities. */ 439 idtab->nentries++; 440 } else { 441 sshkey_free(k); 442 free(id->comment); 443 } 444 id->comment = comment; 445 id->death = death; 446 id->confirm = confirm; 447 send: 448 send_status(e, success); 449 } 450 451 /* XXX todo: encrypt sensitive data with passphrase */ 452 static void 453 process_lock_agent(SocketEntry *e, int lock) 454 { 455 int r, success = 0, delay; 456 char *passwd; 457 u_char passwdhash[LOCK_SIZE]; 458 static u_int fail_count = 0; 459 size_t pwlen; 460 461 /* 462 * This is deliberately fatal: the user has requested that we lock, 463 * but we can't parse their request properly. The only safe thing to 464 * do is abort. 465 */ 466 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 467 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 468 if (pwlen == 0) { 469 debug("empty password not supported"); 470 } else if (locked && !lock) { 471 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 472 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 473 fatal("bcrypt_pbkdf"); 474 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 475 debug("agent unlocked"); 476 locked = 0; 477 fail_count = 0; 478 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 479 success = 1; 480 } else { 481 /* delay in 0.1s increments up to 10s */ 482 if (fail_count < 100) 483 fail_count++; 484 delay = 100000 * fail_count; 485 debug("unlock failed, delaying %0.1lf seconds", 486 (double)delay/1000000); 487 usleep(delay); 488 } 489 explicit_bzero(passwdhash, sizeof(passwdhash)); 490 } else if (!locked && lock) { 491 debug("agent locked"); 492 locked = 1; 493 arc4random_buf(lock_salt, sizeof(lock_salt)); 494 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 495 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 496 fatal("bcrypt_pbkdf"); 497 success = 1; 498 } 499 explicit_bzero(passwd, pwlen); 500 free(passwd); 501 send_status(e, success); 502 } 503 504 static void 505 no_identities(SocketEntry *e) 506 { 507 struct sshbuf *msg; 508 int r; 509 510 if ((msg = sshbuf_new()) == NULL) 511 fatal("%s: sshbuf_new failed", __func__); 512 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 513 (r = sshbuf_put_u32(msg, 0)) != 0 || 514 (r = sshbuf_put_stringb(e->output, msg)) != 0) 515 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 516 sshbuf_free(msg); 517 } 518 519 #ifdef ENABLE_PKCS11 520 static void 521 process_add_smartcard_key(SocketEntry *e) 522 { 523 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 524 int r, i, count = 0, success = 0, confirm = 0; 525 u_int seconds; 526 time_t death = 0; 527 u_char type; 528 struct sshkey **keys = NULL, *k; 529 Identity *id; 530 531 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 532 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 533 error("%s: buffer error: %s", __func__, ssh_err(r)); 534 goto send; 535 } 536 537 while (sshbuf_len(e->request)) { 538 if ((r = sshbuf_get_u8(e->request, &type)) != 0) { 539 error("%s: buffer error: %s", __func__, ssh_err(r)); 540 goto send; 541 } 542 switch (type) { 543 case SSH_AGENT_CONSTRAIN_LIFETIME: 544 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 545 error("%s: buffer error: %s", 546 __func__, ssh_err(r)); 547 goto send; 548 } 549 death = monotime() + seconds; 550 break; 551 case SSH_AGENT_CONSTRAIN_CONFIRM: 552 confirm = 1; 553 break; 554 default: 555 error("%s: Unknown constraint type %d", __func__, type); 556 goto send; 557 } 558 } 559 if (realpath(provider, canonical_provider) == NULL) { 560 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 561 provider, strerror(errno)); 562 goto send; 563 } 564 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 565 verbose("refusing PKCS#11 add of \"%.100s\": " 566 "provider not whitelisted", canonical_provider); 567 goto send; 568 } 569 debug("%s: add %.100s", __func__, canonical_provider); 570 if (lifetime && !death) 571 death = monotime() + lifetime; 572 573 count = pkcs11_add_provider(canonical_provider, pin, &keys); 574 for (i = 0; i < count; i++) { 575 k = keys[i]; 576 if (lookup_identity(k) == NULL) { 577 id = xcalloc(1, sizeof(Identity)); 578 id->key = k; 579 id->provider = xstrdup(canonical_provider); 580 id->comment = xstrdup(canonical_provider); /* XXX */ 581 id->death = death; 582 id->confirm = confirm; 583 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 584 idtab->nentries++; 585 success = 1; 586 } else { 587 sshkey_free(k); 588 } 589 keys[i] = NULL; 590 } 591 send: 592 free(pin); 593 free(provider); 594 free(keys); 595 send_status(e, success); 596 } 597 598 static void 599 process_remove_smartcard_key(SocketEntry *e) 600 { 601 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 602 int r, success = 0; 603 Identity *id, *nxt; 604 605 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 606 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 607 error("%s: buffer error: %s", __func__, ssh_err(r)); 608 goto send; 609 } 610 free(pin); 611 612 if (realpath(provider, canonical_provider) == NULL) { 613 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 614 provider, strerror(errno)); 615 goto send; 616 } 617 618 debug("%s: remove %.100s", __func__, canonical_provider); 619 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 620 nxt = TAILQ_NEXT(id, next); 621 /* Skip file--based keys */ 622 if (id->provider == NULL) 623 continue; 624 if (!strcmp(canonical_provider, id->provider)) { 625 TAILQ_REMOVE(&idtab->idlist, id, next); 626 free_identity(id); 627 idtab->nentries--; 628 } 629 } 630 if (pkcs11_del_provider(canonical_provider) == 0) 631 success = 1; 632 else 633 error("%s: pkcs11_del_provider failed", __func__); 634 send: 635 free(provider); 636 send_status(e, success); 637 } 638 #endif /* ENABLE_PKCS11 */ 639 640 /* dispatch incoming messages */ 641 642 static int 643 process_message(u_int socknum) 644 { 645 u_int msg_len; 646 u_char type; 647 const u_char *cp; 648 int r; 649 SocketEntry *e; 650 651 if (socknum >= sockets_alloc) { 652 fatal("%s: socket number %u >= allocated %u", 653 __func__, socknum, sockets_alloc); 654 } 655 e = &sockets[socknum]; 656 657 if (sshbuf_len(e->input) < 5) 658 return 0; /* Incomplete message header. */ 659 cp = sshbuf_ptr(e->input); 660 msg_len = PEEK_U32(cp); 661 if (msg_len > AGENT_MAX_LEN) { 662 debug("%s: socket %u (fd=%d) message too long %u > %u", 663 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 664 return -1; 665 } 666 if (sshbuf_len(e->input) < msg_len + 4) 667 return 0; /* Incomplete message body. */ 668 669 /* move the current input to e->request */ 670 sshbuf_reset(e->request); 671 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 672 (r = sshbuf_get_u8(e->request, &type)) != 0) { 673 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 674 r == SSH_ERR_STRING_TOO_LARGE) { 675 debug("%s: buffer error: %s", __func__, ssh_err(r)); 676 return -1; 677 } 678 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 679 } 680 681 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 682 683 /* check wheter agent is locked */ 684 if (locked && type != SSH_AGENTC_UNLOCK) { 685 sshbuf_reset(e->request); 686 switch (type) { 687 case SSH2_AGENTC_REQUEST_IDENTITIES: 688 /* send empty lists */ 689 no_identities(e); 690 break; 691 default: 692 /* send a fail message for all other request types */ 693 send_status(e, 0); 694 } 695 return 0; 696 } 697 698 switch (type) { 699 case SSH_AGENTC_LOCK: 700 case SSH_AGENTC_UNLOCK: 701 process_lock_agent(e, type == SSH_AGENTC_LOCK); 702 break; 703 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 704 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 705 break; 706 /* ssh2 */ 707 case SSH2_AGENTC_SIGN_REQUEST: 708 process_sign_request2(e); 709 break; 710 case SSH2_AGENTC_REQUEST_IDENTITIES: 711 process_request_identities(e); 712 break; 713 case SSH2_AGENTC_ADD_IDENTITY: 714 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 715 process_add_identity(e); 716 break; 717 case SSH2_AGENTC_REMOVE_IDENTITY: 718 process_remove_identity(e); 719 break; 720 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 721 process_remove_all_identities(e); 722 break; 723 #ifdef ENABLE_PKCS11 724 case SSH_AGENTC_ADD_SMARTCARD_KEY: 725 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 726 process_add_smartcard_key(e); 727 break; 728 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 729 process_remove_smartcard_key(e); 730 break; 731 #endif /* ENABLE_PKCS11 */ 732 default: 733 /* Unknown message. Respond with failure. */ 734 error("Unknown message %d", type); 735 sshbuf_reset(e->request); 736 send_status(e, 0); 737 break; 738 } 739 return 0; 740 } 741 742 static void 743 new_socket(sock_type type, int fd) 744 { 745 u_int i, old_alloc, new_alloc; 746 747 set_nonblock(fd); 748 749 if (fd > max_fd) 750 max_fd = fd; 751 752 for (i = 0; i < sockets_alloc; i++) 753 if (sockets[i].type == AUTH_UNUSED) { 754 sockets[i].fd = fd; 755 if ((sockets[i].input = sshbuf_new()) == NULL) 756 fatal("%s: sshbuf_new failed", __func__); 757 if ((sockets[i].output = sshbuf_new()) == NULL) 758 fatal("%s: sshbuf_new failed", __func__); 759 if ((sockets[i].request = sshbuf_new()) == NULL) 760 fatal("%s: sshbuf_new failed", __func__); 761 sockets[i].type = type; 762 return; 763 } 764 old_alloc = sockets_alloc; 765 new_alloc = sockets_alloc + 10; 766 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 767 for (i = old_alloc; i < new_alloc; i++) 768 sockets[i].type = AUTH_UNUSED; 769 sockets_alloc = new_alloc; 770 sockets[old_alloc].fd = fd; 771 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 772 fatal("%s: sshbuf_new failed", __func__); 773 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 774 fatal("%s: sshbuf_new failed", __func__); 775 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 776 fatal("%s: sshbuf_new failed", __func__); 777 sockets[old_alloc].type = type; 778 } 779 780 static int 781 handle_socket_read(u_int socknum) 782 { 783 struct sockaddr_un sunaddr; 784 socklen_t slen; 785 uid_t euid; 786 gid_t egid; 787 int fd; 788 789 slen = sizeof(sunaddr); 790 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 791 if (fd < 0) { 792 error("accept from AUTH_SOCKET: %s", strerror(errno)); 793 return -1; 794 } 795 if (getpeereid(fd, &euid, &egid) < 0) { 796 error("getpeereid %d failed: %s", fd, strerror(errno)); 797 close(fd); 798 return -1; 799 } 800 if ((euid != 0) && (getuid() != euid)) { 801 error("uid mismatch: peer euid %u != uid %u", 802 (u_int) euid, (u_int) getuid()); 803 close(fd); 804 return -1; 805 } 806 new_socket(AUTH_CONNECTION, fd); 807 return 0; 808 } 809 810 static int 811 handle_conn_read(u_int socknum) 812 { 813 char buf[1024]; 814 ssize_t len; 815 int r; 816 817 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 818 if (len == -1) { 819 if (errno == EAGAIN || errno == EINTR) 820 return 0; 821 error("%s: read error on socket %u (fd %d): %s", 822 __func__, socknum, sockets[socknum].fd, 823 strerror(errno)); 824 } 825 return -1; 826 } 827 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 828 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 829 explicit_bzero(buf, sizeof(buf)); 830 process_message(socknum); 831 return 0; 832 } 833 834 static int 835 handle_conn_write(u_int socknum) 836 { 837 ssize_t len; 838 int r; 839 840 if (sshbuf_len(sockets[socknum].output) == 0) 841 return 0; /* shouldn't happen */ 842 if ((len = write(sockets[socknum].fd, 843 sshbuf_ptr(sockets[socknum].output), 844 sshbuf_len(sockets[socknum].output))) <= 0) { 845 if (len == -1) { 846 if (errno == EAGAIN || errno == EINTR) 847 return 0; 848 error("%s: read error on socket %u (fd %d): %s", 849 __func__, socknum, sockets[socknum].fd, 850 strerror(errno)); 851 } 852 return -1; 853 } 854 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 855 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 856 return 0; 857 } 858 859 static void 860 after_poll(struct pollfd *pfd, size_t npfd) 861 { 862 size_t i; 863 u_int socknum; 864 865 for (i = 0; i < npfd; i++) { 866 if (pfd[i].revents == 0) 867 continue; 868 /* Find sockets entry */ 869 for (socknum = 0; socknum < sockets_alloc; socknum++) { 870 if (sockets[socknum].type != AUTH_SOCKET && 871 sockets[socknum].type != AUTH_CONNECTION) 872 continue; 873 if (pfd[i].fd == sockets[socknum].fd) 874 break; 875 } 876 if (socknum >= sockets_alloc) { 877 error("%s: no socket for fd %d", __func__, pfd[i].fd); 878 continue; 879 } 880 /* Process events */ 881 switch (sockets[socknum].type) { 882 case AUTH_SOCKET: 883 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 884 handle_socket_read(socknum) != 0) 885 close_socket(&sockets[socknum]); 886 break; 887 case AUTH_CONNECTION: 888 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 889 handle_conn_read(socknum) != 0) { 890 close_socket(&sockets[socknum]); 891 break; 892 } 893 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 894 handle_conn_write(socknum) != 0) 895 close_socket(&sockets[socknum]); 896 break; 897 default: 898 break; 899 } 900 } 901 } 902 903 static int 904 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp) 905 { 906 struct pollfd *pfd = *pfdp; 907 size_t i, j, npfd = 0; 908 time_t deadline; 909 910 /* Count active sockets */ 911 for (i = 0; i < sockets_alloc; i++) { 912 switch (sockets[i].type) { 913 case AUTH_SOCKET: 914 case AUTH_CONNECTION: 915 npfd++; 916 break; 917 case AUTH_UNUSED: 918 break; 919 default: 920 fatal("Unknown socket type %d", sockets[i].type); 921 break; 922 } 923 } 924 if (npfd != *npfdp && 925 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 926 fatal("%s: recallocarray failed", __func__); 927 *pfdp = pfd; 928 *npfdp = npfd; 929 930 for (i = j = 0; i < sockets_alloc; i++) { 931 switch (sockets[i].type) { 932 case AUTH_SOCKET: 933 case AUTH_CONNECTION: 934 pfd[j].fd = sockets[i].fd; 935 pfd[j].revents = 0; 936 /* XXX backoff when input buffer full */ 937 pfd[j].events = POLLIN; 938 if (sshbuf_len(sockets[i].output) > 0) 939 pfd[j].events |= POLLOUT; 940 j++; 941 break; 942 default: 943 break; 944 } 945 } 946 deadline = reaper(); 947 if (parent_alive_interval != 0) 948 deadline = (deadline == 0) ? parent_alive_interval : 949 MINIMUM(deadline, parent_alive_interval); 950 if (deadline == 0) { 951 *timeoutp = -1; /* INFTIM */ 952 } else { 953 if (deadline > INT_MAX / 1000) 954 *timeoutp = INT_MAX / 1000; 955 else 956 *timeoutp = deadline * 1000; 957 } 958 return (1); 959 } 960 961 static void 962 cleanup_socket(void) 963 { 964 if (cleanup_pid != 0 && getpid() != cleanup_pid) 965 return; 966 debug("%s: cleanup", __func__); 967 if (socket_name[0]) 968 unlink(socket_name); 969 if (socket_dir[0]) 970 rmdir(socket_dir); 971 } 972 973 void 974 cleanup_exit(int i) 975 { 976 cleanup_socket(); 977 _exit(i); 978 } 979 980 /*ARGSUSED*/ 981 static void 982 cleanup_handler(int sig) 983 { 984 cleanup_socket(); 985 #ifdef ENABLE_PKCS11 986 pkcs11_terminate(); 987 #endif 988 _exit(2); 989 } 990 991 static void 992 check_parent_exists(void) 993 { 994 /* 995 * If our parent has exited then getppid() will return (pid_t)1, 996 * so testing for that should be safe. 997 */ 998 if (parent_pid != -1 && getppid() != parent_pid) { 999 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1000 cleanup_socket(); 1001 _exit(2); 1002 } 1003 } 1004 1005 static void 1006 usage(void) 1007 { 1008 fprintf(stderr, 1009 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1010 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 1011 " ssh-agent [-c | -s] -k\n"); 1012 exit(1); 1013 } 1014 1015 int 1016 main(int ac, char **av) 1017 { 1018 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1019 int sock, fd, ch, result, saved_errno; 1020 char *shell, *format, *pidstr, *agentsocket = NULL; 1021 struct rlimit rlim; 1022 extern int optind; 1023 extern char *optarg; 1024 pid_t pid; 1025 char pidstrbuf[1 + 3 * sizeof pid]; 1026 size_t len; 1027 mode_t prev_mask; 1028 int timeout = -1; /* INFTIM */ 1029 struct pollfd *pfd = NULL; 1030 size_t npfd = 0; 1031 1032 ssh_malloc_init(); /* must be called before any mallocs */ 1033 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1034 sanitise_stdfd(); 1035 1036 /* drop */ 1037 setegid(getgid()); 1038 setgid(getgid()); 1039 1040 #ifdef WITH_OPENSSL 1041 OpenSSL_add_all_algorithms(); 1042 #endif 1043 1044 while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) { 1045 switch (ch) { 1046 case 'E': 1047 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1048 if (fingerprint_hash == -1) 1049 fatal("Invalid hash algorithm \"%s\"", optarg); 1050 break; 1051 case 'c': 1052 if (s_flag) 1053 usage(); 1054 c_flag++; 1055 break; 1056 case 'k': 1057 k_flag++; 1058 break; 1059 case 'P': 1060 if (pkcs11_whitelist != NULL) 1061 fatal("-P option already specified"); 1062 pkcs11_whitelist = xstrdup(optarg); 1063 break; 1064 case 's': 1065 if (c_flag) 1066 usage(); 1067 s_flag++; 1068 break; 1069 case 'd': 1070 if (d_flag || D_flag) 1071 usage(); 1072 d_flag++; 1073 break; 1074 case 'D': 1075 if (d_flag || D_flag) 1076 usage(); 1077 D_flag++; 1078 break; 1079 case 'a': 1080 agentsocket = optarg; 1081 break; 1082 case 't': 1083 if ((lifetime = convtime(optarg)) == -1) { 1084 fprintf(stderr, "Invalid lifetime\n"); 1085 usage(); 1086 } 1087 break; 1088 default: 1089 usage(); 1090 } 1091 } 1092 ac -= optind; 1093 av += optind; 1094 1095 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1096 usage(); 1097 1098 if (pkcs11_whitelist == NULL) 1099 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1100 1101 if (ac == 0 && !c_flag && !s_flag) { 1102 shell = getenv("SHELL"); 1103 if (shell != NULL && (len = strlen(shell)) > 2 && 1104 strncmp(shell + len - 3, "csh", 3) == 0) 1105 c_flag = 1; 1106 } 1107 if (k_flag) { 1108 const char *errstr = NULL; 1109 1110 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1111 if (pidstr == NULL) { 1112 fprintf(stderr, "%s not set, cannot kill agent\n", 1113 SSH_AGENTPID_ENV_NAME); 1114 exit(1); 1115 } 1116 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1117 if (errstr) { 1118 fprintf(stderr, 1119 "%s=\"%s\", which is not a good PID: %s\n", 1120 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1121 exit(1); 1122 } 1123 if (kill(pid, SIGTERM) == -1) { 1124 perror("kill"); 1125 exit(1); 1126 } 1127 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1128 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1129 printf(format, SSH_AGENTPID_ENV_NAME); 1130 printf("echo Agent pid %ld killed;\n", (long)pid); 1131 exit(0); 1132 } 1133 parent_pid = getpid(); 1134 1135 if (agentsocket == NULL) { 1136 /* Create private directory for agent socket */ 1137 mktemp_proto(socket_dir, sizeof(socket_dir)); 1138 if (mkdtemp(socket_dir) == NULL) { 1139 perror("mkdtemp: private socket dir"); 1140 exit(1); 1141 } 1142 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1143 (long)parent_pid); 1144 } else { 1145 /* Try to use specified agent socket */ 1146 socket_dir[0] = '\0'; 1147 strlcpy(socket_name, agentsocket, sizeof socket_name); 1148 } 1149 1150 /* 1151 * Create socket early so it will exist before command gets run from 1152 * the parent. 1153 */ 1154 prev_mask = umask(0177); 1155 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1156 if (sock < 0) { 1157 /* XXX - unix_listener() calls error() not perror() */ 1158 *socket_name = '\0'; /* Don't unlink any existing file */ 1159 cleanup_exit(1); 1160 } 1161 umask(prev_mask); 1162 1163 /* 1164 * Fork, and have the parent execute the command, if any, or present 1165 * the socket data. The child continues as the authentication agent. 1166 */ 1167 if (D_flag || d_flag) { 1168 log_init(__progname, 1169 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1170 SYSLOG_FACILITY_AUTH, 1); 1171 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1172 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1173 SSH_AUTHSOCKET_ENV_NAME); 1174 printf("echo Agent pid %ld;\n", (long)parent_pid); 1175 fflush(stdout); 1176 goto skip; 1177 } 1178 pid = fork(); 1179 if (pid == -1) { 1180 perror("fork"); 1181 cleanup_exit(1); 1182 } 1183 if (pid != 0) { /* Parent - execute the given command. */ 1184 close(sock); 1185 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1186 if (ac == 0) { 1187 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1188 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1189 SSH_AUTHSOCKET_ENV_NAME); 1190 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1191 SSH_AGENTPID_ENV_NAME); 1192 printf("echo Agent pid %ld;\n", (long)pid); 1193 exit(0); 1194 } 1195 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1196 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1197 perror("setenv"); 1198 exit(1); 1199 } 1200 execvp(av[0], av); 1201 perror(av[0]); 1202 exit(1); 1203 } 1204 /* child */ 1205 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1206 1207 if (setsid() == -1) { 1208 error("setsid: %s", strerror(errno)); 1209 cleanup_exit(1); 1210 } 1211 1212 (void)chdir("/"); 1213 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1214 /* XXX might close listen socket */ 1215 (void)dup2(fd, STDIN_FILENO); 1216 (void)dup2(fd, STDOUT_FILENO); 1217 (void)dup2(fd, STDERR_FILENO); 1218 if (fd > 2) 1219 close(fd); 1220 } 1221 1222 /* deny core dumps, since memory contains unencrypted private keys */ 1223 rlim.rlim_cur = rlim.rlim_max = 0; 1224 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1225 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1226 cleanup_exit(1); 1227 } 1228 1229 skip: 1230 1231 cleanup_pid = getpid(); 1232 1233 #ifdef ENABLE_PKCS11 1234 pkcs11_init(0); 1235 #endif 1236 new_socket(AUTH_SOCKET, sock); 1237 if (ac > 0) 1238 parent_alive_interval = 10; 1239 idtab_init(); 1240 signal(SIGPIPE, SIG_IGN); 1241 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1242 signal(SIGHUP, cleanup_handler); 1243 signal(SIGTERM, cleanup_handler); 1244 1245 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1246 fatal("%s: pledge: %s", __progname, strerror(errno)); 1247 1248 while (1) { 1249 prepare_poll(&pfd, &npfd, &timeout); 1250 result = poll(pfd, npfd, timeout); 1251 saved_errno = errno; 1252 if (parent_alive_interval != 0) 1253 check_parent_exists(); 1254 (void) reaper(); /* remove expired keys */ 1255 if (result < 0) { 1256 if (saved_errno == EINTR) 1257 continue; 1258 fatal("poll: %s", strerror(saved_errno)); 1259 } else if (result > 0) 1260 after_poll(pfd, npfd); 1261 } 1262 /* NOTREACHED */ 1263 } 1264