1 /* $NetBSD: ssh-agent.c,v 1.21 2017/10/07 19:39:19 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.224 2017/07/24 04:34:28 djm Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * The authentication agent program. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 __RCSID("$NetBSD: ssh-agent.c,v 1.21 2017/10/07 19:39:19 christos Exp $"); 40 41 #include <sys/param.h> /* MIN MAX */ 42 #include <sys/types.h> 43 #include <sys/time.h> 44 #include <sys/queue.h> 45 #include <sys/resource.h> 46 #include <sys/socket.h> 47 #include <sys/stat.h> 48 #include <sys/un.h> 49 50 #ifdef WITH_OPENSSL 51 #include <openssl/evp.h> 52 #endif 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <paths.h> 57 #include <poll.h> 58 #include <signal.h> 59 #include <stdlib.h> 60 #include <stdio.h> 61 #include <string.h> 62 #include <limits.h> 63 #include <time.h> 64 #include <unistd.h> 65 #include <util.h> 66 67 #include "xmalloc.h" 68 #include "ssh.h" 69 #include "sshbuf.h" 70 #include "sshkey.h" 71 #include "authfd.h" 72 #include "compat.h" 73 #include "log.h" 74 #include "misc.h" 75 #include "getpeereid.h" 76 #include "digest.h" 77 #include "ssherr.h" 78 #include "match.h" 79 80 #ifdef ENABLE_PKCS11 81 #include "ssh-pkcs11.h" 82 #endif 83 84 #ifndef DEFAULT_PKCS11_WHITELIST 85 # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" 86 #endif 87 88 /* Maximum accepted message length */ 89 #define AGENT_MAX_LEN (256*1024) 90 91 typedef enum { 92 AUTH_UNUSED, 93 AUTH_SOCKET, 94 AUTH_CONNECTION 95 } sock_type; 96 97 typedef struct { 98 int fd; 99 sock_type type; 100 struct sshbuf *input; 101 struct sshbuf *output; 102 struct sshbuf *request; 103 } SocketEntry; 104 105 u_int sockets_alloc = 0; 106 SocketEntry *sockets = NULL; 107 108 typedef struct identity { 109 TAILQ_ENTRY(identity) next; 110 struct sshkey *key; 111 char *comment; 112 char *provider; 113 time_t death; 114 u_int confirm; 115 } Identity; 116 117 struct idtable { 118 int nentries; 119 TAILQ_HEAD(idqueue, identity) idlist; 120 }; 121 122 /* private key table */ 123 struct idtable *idtab; 124 125 int max_fd = 0; 126 127 /* pid of shell == parent of agent */ 128 pid_t parent_pid = -1; 129 time_t parent_alive_interval = 0; 130 131 /* pid of process for which cleanup_socket is applicable */ 132 pid_t cleanup_pid = 0; 133 134 /* pathname and directory for AUTH_SOCKET */ 135 char socket_name[PATH_MAX]; 136 char socket_dir[PATH_MAX]; 137 138 /* PKCS#11 path whitelist */ 139 static char *pkcs11_whitelist; 140 141 /* locking */ 142 #define LOCK_SIZE 32 143 #define LOCK_SALT_SIZE 16 144 #define LOCK_ROUNDS 1 145 int locked = 0; 146 u_char lock_pwhash[LOCK_SIZE]; 147 u_char lock_salt[LOCK_SALT_SIZE]; 148 149 extern char *__progname; 150 151 /* Default lifetime in seconds (0 == forever) */ 152 static long lifetime = 0; 153 154 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 155 156 static void 157 close_socket(SocketEntry *e) 158 { 159 close(e->fd); 160 e->fd = -1; 161 e->type = AUTH_UNUSED; 162 sshbuf_free(e->input); 163 sshbuf_free(e->output); 164 sshbuf_free(e->request); 165 } 166 167 static void 168 idtab_init(void) 169 { 170 idtab = xcalloc(1, sizeof(*idtab)); 171 TAILQ_INIT(&idtab->idlist); 172 idtab->nentries = 0; 173 } 174 175 static void 176 free_identity(Identity *id) 177 { 178 sshkey_free(id->key); 179 free(id->provider); 180 free(id->comment); 181 free(id); 182 } 183 184 /* return matching private key for given public key */ 185 static Identity * 186 lookup_identity(struct sshkey *key) 187 { 188 Identity *id; 189 190 TAILQ_FOREACH(id, &idtab->idlist, next) { 191 if (sshkey_equal(key, id->key)) 192 return (id); 193 } 194 return (NULL); 195 } 196 197 /* Check confirmation of keysign request */ 198 static int 199 confirm_key(Identity *id) 200 { 201 char *p; 202 int ret = -1; 203 204 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 205 if (p != NULL && 206 ask_permission("Allow use of key %s?\nKey fingerprint %s.", 207 id->comment, p)) 208 ret = 0; 209 free(p); 210 211 return (ret); 212 } 213 214 static void 215 send_status(SocketEntry *e, int success) 216 { 217 int r; 218 219 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 220 (r = sshbuf_put_u8(e->output, success ? 221 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 222 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 223 } 224 225 /* send list of supported public keys to 'client' */ 226 static void 227 process_request_identities(SocketEntry *e) 228 { 229 Identity *id; 230 struct sshbuf *msg; 231 int r; 232 233 if ((msg = sshbuf_new()) == NULL) 234 fatal("%s: sshbuf_new failed", __func__); 235 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 236 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 237 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 238 TAILQ_FOREACH(id, &idtab->idlist, next) { 239 if ((r = sshkey_puts(id->key, msg)) != 0 || 240 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 241 error("%s: put key/comment: %s", __func__, 242 ssh_err(r)); 243 continue; 244 } 245 } 246 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 247 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 248 sshbuf_free(msg); 249 } 250 251 252 static const char * 253 agent_decode_alg(struct sshkey *key, u_int flags) 254 { 255 if (key->type == KEY_RSA) { 256 if (flags & SSH_AGENT_RSA_SHA2_256) 257 return "rsa-sha2-256"; 258 else if (flags & SSH_AGENT_RSA_SHA2_512) 259 return "rsa-sha2-512"; 260 } 261 return NULL; 262 } 263 264 /* ssh2 only */ 265 static void 266 process_sign_request2(SocketEntry *e) 267 { 268 const u_char *data; 269 u_char *signature = NULL; 270 size_t dlen, slen = 0; 271 u_int compat = 0, flags; 272 int r, ok = -1; 273 struct sshbuf *msg; 274 struct sshkey *key = NULL; 275 struct identity *id; 276 277 if ((msg = sshbuf_new()) == NULL) 278 fatal("%s: sshbuf_new failed", __func__); 279 if ((r = sshkey_froms(e->request, &key)) != 0 || 280 (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 || 281 (r = sshbuf_get_u32(e->request, &flags)) != 0) 282 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 283 if (flags & SSH_AGENT_OLD_SIGNATURE) 284 compat = SSH_BUG_SIGBLOB; 285 if ((id = lookup_identity(key)) == NULL) { 286 verbose("%s: %s key not found", __func__, sshkey_type(key)); 287 goto send; 288 } 289 if (id->confirm && confirm_key(id) != 0) { 290 verbose("%s: user refused key", __func__); 291 goto send; 292 } 293 if ((r = sshkey_sign(id->key, &signature, &slen, 294 data, dlen, agent_decode_alg(key, flags), compat)) != 0) { 295 error("%s: sshkey_sign: %s", __func__, ssh_err(r)); 296 goto send; 297 } 298 /* Success */ 299 ok = 0; 300 send: 301 sshkey_free(key); 302 if (ok == 0) { 303 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 304 (r = sshbuf_put_string(msg, signature, slen)) != 0) 305 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 306 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 307 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 308 309 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 310 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 311 312 sshbuf_free(msg); 313 free(signature); 314 } 315 316 /* shared */ 317 static void 318 process_remove_identity(SocketEntry *e) 319 { 320 int r, success = 0; 321 struct sshkey *key = NULL; 322 Identity *id; 323 324 if ((r = sshkey_froms(e->request, &key)) != 0) { 325 error("%s: get key: %s", __func__, ssh_err(r)); 326 goto done; 327 } 328 if ((id = lookup_identity(key)) == NULL) { 329 debug("%s: key not found", __func__); 330 goto done; 331 } 332 /* We have this key, free it. */ 333 if (idtab->nentries < 1) 334 fatal("%s: internal error: nentries %d", 335 __func__, idtab->nentries); 336 TAILQ_REMOVE(&idtab->idlist, id, next); 337 free_identity(id); 338 idtab->nentries--; 339 sshkey_free(key); 340 success = 1; 341 done: 342 send_status(e, success); 343 } 344 345 static void 346 process_remove_all_identities(SocketEntry *e) 347 { 348 Identity *id; 349 350 /* Loop over all identities and clear the keys. */ 351 for (id = TAILQ_FIRST(&idtab->idlist); id; 352 id = TAILQ_FIRST(&idtab->idlist)) { 353 TAILQ_REMOVE(&idtab->idlist, id, next); 354 free_identity(id); 355 } 356 357 /* Mark that there are no identities. */ 358 idtab->nentries = 0; 359 360 /* Send success. */ 361 send_status(e, 1); 362 } 363 364 /* removes expired keys and returns number of seconds until the next expiry */ 365 static time_t 366 reaper(void) 367 { 368 time_t deadline = 0, now = monotime(); 369 Identity *id, *nxt; 370 371 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 372 nxt = TAILQ_NEXT(id, next); 373 if (id->death == 0) 374 continue; 375 if (now >= id->death) { 376 debug("expiring key '%s'", id->comment); 377 TAILQ_REMOVE(&idtab->idlist, id, next); 378 free_identity(id); 379 idtab->nentries--; 380 } else 381 deadline = (deadline == 0) ? id->death : 382 MINIMUM(deadline, id->death); 383 } 384 if (deadline == 0 || deadline <= now) 385 return 0; 386 else 387 return (deadline - now); 388 } 389 390 static void 391 process_add_identity(SocketEntry *e) 392 { 393 Identity *id; 394 int success = 0, confirm = 0; 395 u_int seconds; 396 char *comment = NULL; 397 time_t death = 0; 398 struct sshkey *k = NULL; 399 u_char ctype; 400 int r = SSH_ERR_INTERNAL_ERROR; 401 402 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 403 k == NULL || 404 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 405 error("%s: decode private key: %s", __func__, ssh_err(r)); 406 goto err; 407 } 408 409 while (sshbuf_len(e->request)) { 410 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) { 411 error("%s: buffer error: %s", __func__, ssh_err(r)); 412 goto err; 413 } 414 switch (ctype) { 415 case SSH_AGENT_CONSTRAIN_LIFETIME: 416 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) { 417 error("%s: bad lifetime constraint: %s", 418 __func__, ssh_err(r)); 419 goto err; 420 } 421 death = monotime() + seconds; 422 break; 423 case SSH_AGENT_CONSTRAIN_CONFIRM: 424 confirm = 1; 425 break; 426 default: 427 error("%s: Unknown constraint %d", __func__, ctype); 428 err: 429 sshbuf_reset(e->request); 430 free(comment); 431 sshkey_free(k); 432 goto send; 433 } 434 } 435 436 success = 1; 437 if (lifetime && !death) 438 death = monotime() + lifetime; 439 if ((id = lookup_identity(k)) == NULL) { 440 id = xcalloc(1, sizeof(Identity)); 441 id->key = k; 442 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 443 /* Increment the number of identities. */ 444 idtab->nentries++; 445 } else { 446 sshkey_free(k); 447 free(id->comment); 448 } 449 id->comment = comment; 450 id->death = death; 451 id->confirm = confirm; 452 send: 453 send_status(e, success); 454 } 455 456 /* XXX todo: encrypt sensitive data with passphrase */ 457 static void 458 process_lock_agent(SocketEntry *e, int lock) 459 { 460 int r, success = 0, delay; 461 char *passwd; 462 u_char passwdhash[LOCK_SIZE]; 463 static u_int fail_count = 0; 464 size_t pwlen; 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, (uint8_t *)lock_salt, sizeof(lock_salt), 472 (uint8_t *)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, 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 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 534 535 while (sshbuf_len(e->request)) { 536 if ((r = sshbuf_get_u8(e->request, &type)) != 0) 537 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 538 switch (type) { 539 case SSH_AGENT_CONSTRAIN_LIFETIME: 540 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) 541 fatal("%s: buffer error: %s", 542 __func__, ssh_err(r)); 543 death = monotime() + seconds; 544 break; 545 case SSH_AGENT_CONSTRAIN_CONFIRM: 546 confirm = 1; 547 break; 548 default: 549 error("%s: Unknown constraint type %d", __func__, type); 550 goto send; 551 } 552 } 553 if (realpath(provider, canonical_provider) == NULL) { 554 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 555 provider, strerror(errno)); 556 goto send; 557 } 558 if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { 559 verbose("refusing PKCS#11 add of \"%.100s\": " 560 "provider not whitelisted", canonical_provider); 561 goto send; 562 } 563 debug("%s: add %.100s", __func__, canonical_provider); 564 if (lifetime && !death) 565 death = monotime() + lifetime; 566 567 count = pkcs11_add_provider(canonical_provider, pin, &keys); 568 for (i = 0; i < count; i++) { 569 k = keys[i]; 570 if (lookup_identity(k) == NULL) { 571 id = xcalloc(1, sizeof(Identity)); 572 id->key = k; 573 id->provider = xstrdup(canonical_provider); 574 id->comment = xstrdup(canonical_provider); /* XXX */ 575 id->death = death; 576 id->confirm = confirm; 577 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 578 idtab->nentries++; 579 success = 1; 580 } else { 581 sshkey_free(k); 582 } 583 keys[i] = NULL; 584 } 585 send: 586 free(pin); 587 free(provider); 588 free(keys); 589 send_status(e, success); 590 } 591 592 static void 593 process_remove_smartcard_key(SocketEntry *e) 594 { 595 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 596 int r, success = 0; 597 Identity *id, *nxt; 598 599 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 600 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) 601 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 602 free(pin); 603 604 if (realpath(provider, canonical_provider) == NULL) { 605 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 606 provider, strerror(errno)); 607 goto send; 608 } 609 610 debug("%s: remove %.100s", __func__, canonical_provider); 611 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 612 nxt = TAILQ_NEXT(id, next); 613 /* Skip file--based keys */ 614 if (id->provider == NULL) 615 continue; 616 if (!strcmp(canonical_provider, id->provider)) { 617 TAILQ_REMOVE(&idtab->idlist, id, next); 618 free_identity(id); 619 idtab->nentries--; 620 } 621 } 622 if (pkcs11_del_provider(canonical_provider) == 0) 623 success = 1; 624 else 625 error("%s: pkcs11_del_provider failed", __func__); 626 send: 627 free(provider); 628 send_status(e, success); 629 } 630 #endif /* ENABLE_PKCS11 */ 631 632 /* dispatch incoming messages */ 633 634 static int 635 process_message(u_int socknum) 636 { 637 u_int msg_len; 638 u_char type; 639 const u_char *cp; 640 int r; 641 SocketEntry *e; 642 643 if (socknum >= sockets_alloc) { 644 fatal("%s: socket number %u >= allocated %u", 645 __func__, socknum, sockets_alloc); 646 } 647 e = &sockets[socknum]; 648 649 if (sshbuf_len(e->input) < 5) 650 return 0; /* Incomplete message header. */ 651 cp = sshbuf_ptr(e->input); 652 msg_len = PEEK_U32(cp); 653 if (msg_len > AGENT_MAX_LEN) { 654 debug("%s: socket %u (fd=%d) message too long %u > %u", 655 __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN); 656 return -1; 657 } 658 if (sshbuf_len(e->input) < msg_len + 4) 659 return 0; /* Incomplete message body. */ 660 661 /* move the current input to e->request */ 662 sshbuf_reset(e->request); 663 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 664 (r = sshbuf_get_u8(e->request, &type)) != 0) { 665 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 666 r == SSH_ERR_STRING_TOO_LARGE) { 667 debug("%s: buffer error: %s", __func__, ssh_err(r)); 668 return -1; 669 } 670 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 671 } 672 673 debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type); 674 675 /* check wheter agent is locked */ 676 if (locked && type != SSH_AGENTC_UNLOCK) { 677 sshbuf_reset(e->request); 678 switch (type) { 679 case SSH2_AGENTC_REQUEST_IDENTITIES: 680 /* send empty lists */ 681 no_identities(e); 682 break; 683 default: 684 /* send a fail message for all other request types */ 685 send_status(e, 0); 686 } 687 return 0; 688 } 689 690 switch (type) { 691 case SSH_AGENTC_LOCK: 692 case SSH_AGENTC_UNLOCK: 693 process_lock_agent(e, type == SSH_AGENTC_LOCK); 694 break; 695 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 696 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 697 break; 698 /* ssh2 */ 699 case SSH2_AGENTC_SIGN_REQUEST: 700 process_sign_request2(e); 701 break; 702 case SSH2_AGENTC_REQUEST_IDENTITIES: 703 process_request_identities(e); 704 break; 705 case SSH2_AGENTC_ADD_IDENTITY: 706 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 707 process_add_identity(e); 708 break; 709 case SSH2_AGENTC_REMOVE_IDENTITY: 710 process_remove_identity(e); 711 break; 712 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 713 process_remove_all_identities(e); 714 break; 715 #ifdef ENABLE_PKCS11 716 case SSH_AGENTC_ADD_SMARTCARD_KEY: 717 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 718 process_add_smartcard_key(e); 719 break; 720 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 721 process_remove_smartcard_key(e); 722 break; 723 #endif /* ENABLE_PKCS11 */ 724 default: 725 /* Unknown message. Respond with failure. */ 726 error("Unknown message %d", type); 727 sshbuf_reset(e->request); 728 send_status(e, 0); 729 break; 730 } 731 return 0; 732 } 733 734 static void 735 new_socket(sock_type type, int fd) 736 { 737 u_int i, old_alloc, new_alloc; 738 739 set_nonblock(fd); 740 741 if (fd > max_fd) 742 max_fd = fd; 743 744 for (i = 0; i < sockets_alloc; i++) 745 if (sockets[i].type == AUTH_UNUSED) { 746 sockets[i].fd = fd; 747 if ((sockets[i].input = sshbuf_new()) == NULL) 748 fatal("%s: sshbuf_new failed", __func__); 749 if ((sockets[i].output = sshbuf_new()) == NULL) 750 fatal("%s: sshbuf_new failed", __func__); 751 if ((sockets[i].request = sshbuf_new()) == NULL) 752 fatal("%s: sshbuf_new failed", __func__); 753 sockets[i].type = type; 754 return; 755 } 756 old_alloc = sockets_alloc; 757 new_alloc = sockets_alloc + 10; 758 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0])); 759 for (i = old_alloc; i < new_alloc; i++) 760 sockets[i].type = AUTH_UNUSED; 761 sockets_alloc = new_alloc; 762 sockets[old_alloc].fd = fd; 763 if ((sockets[old_alloc].input = sshbuf_new()) == NULL) 764 fatal("%s: sshbuf_new failed", __func__); 765 if ((sockets[old_alloc].output = sshbuf_new()) == NULL) 766 fatal("%s: sshbuf_new failed", __func__); 767 if ((sockets[old_alloc].request = sshbuf_new()) == NULL) 768 fatal("%s: sshbuf_new failed", __func__); 769 sockets[old_alloc].type = type; 770 } 771 772 static int 773 handle_socket_read(u_int socknum) 774 { 775 struct sockaddr_un sunaddr; 776 socklen_t slen; 777 uid_t euid; 778 gid_t egid; 779 int fd; 780 781 slen = sizeof(sunaddr); 782 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 783 if (fd < 0) { 784 error("accept from AUTH_SOCKET: %s", strerror(errno)); 785 return -1; 786 } 787 if (getpeereid(fd, &euid, &egid) < 0) { 788 error("getpeereid %d failed: %s", fd, strerror(errno)); 789 close(fd); 790 return -1; 791 } 792 if ((euid != 0) && (getuid() != euid)) { 793 error("uid mismatch: peer euid %u != uid %u", 794 (u_int) euid, (u_int) getuid()); 795 close(fd); 796 return -1; 797 } 798 new_socket(AUTH_CONNECTION, fd); 799 return 0; 800 } 801 802 static int 803 handle_conn_read(u_int socknum) 804 { 805 char buf[1024]; 806 ssize_t len; 807 int r; 808 809 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 810 if (len == -1) { 811 if (errno == EAGAIN || errno == EINTR) 812 return 0; 813 error("%s: read error on socket %u (fd %d): %s", 814 __func__, socknum, sockets[socknum].fd, 815 strerror(errno)); 816 } 817 return -1; 818 } 819 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 820 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 821 explicit_bzero(buf, sizeof(buf)); 822 process_message(socknum); 823 return 0; 824 } 825 826 static int 827 handle_conn_write(u_int socknum) 828 { 829 ssize_t len; 830 int r; 831 832 if (sshbuf_len(sockets[socknum].output) == 0) 833 return 0; /* shouldn't happen */ 834 if ((len = write(sockets[socknum].fd, 835 sshbuf_ptr(sockets[socknum].output), 836 sshbuf_len(sockets[socknum].output))) <= 0) { 837 if (len == -1) { 838 if (errno == EAGAIN || errno == EINTR) 839 return 0; 840 error("%s: read error on socket %u (fd %d): %s", 841 __func__, socknum, sockets[socknum].fd, 842 strerror(errno)); 843 } 844 return -1; 845 } 846 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 847 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 848 return 0; 849 } 850 851 static void 852 after_poll(struct pollfd *pfd, size_t npfd) 853 { 854 size_t i; 855 u_int socknum; 856 857 for (i = 0; i < npfd; i++) { 858 if (pfd[i].revents == 0) 859 continue; 860 /* Find sockets entry */ 861 for (socknum = 0; socknum < sockets_alloc; socknum++) { 862 if (sockets[socknum].type != AUTH_SOCKET && 863 sockets[socknum].type != AUTH_CONNECTION) 864 continue; 865 if (pfd[i].fd == sockets[socknum].fd) 866 break; 867 } 868 if (socknum >= sockets_alloc) { 869 error("%s: no socket for fd %d", __func__, pfd[i].fd); 870 continue; 871 } 872 /* Process events */ 873 switch (sockets[socknum].type) { 874 case AUTH_SOCKET: 875 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 876 handle_socket_read(socknum) != 0) 877 close_socket(&sockets[socknum]); 878 break; 879 case AUTH_CONNECTION: 880 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 881 handle_conn_read(socknum) != 0) { 882 close_socket(&sockets[socknum]); 883 break; 884 } 885 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 886 handle_conn_write(socknum) != 0) 887 close_socket(&sockets[socknum]); 888 break; 889 default: 890 break; 891 } 892 } 893 } 894 895 static int 896 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp) 897 { 898 struct pollfd *pfd = *pfdp; 899 size_t i, j, npfd = 0; 900 time_t deadline; 901 902 /* Count active sockets */ 903 for (i = 0; i < sockets_alloc; i++) { 904 switch (sockets[i].type) { 905 case AUTH_SOCKET: 906 case AUTH_CONNECTION: 907 npfd++; 908 break; 909 case AUTH_UNUSED: 910 break; 911 default: 912 fatal("Unknown socket type %d", sockets[i].type); 913 break; 914 } 915 } 916 if (npfd != *npfdp && 917 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 918 fatal("%s: recallocarray failed", __func__); 919 *pfdp = pfd; 920 *npfdp = npfd; 921 922 for (i = j = 0; i < sockets_alloc; i++) { 923 switch (sockets[i].type) { 924 case AUTH_SOCKET: 925 case AUTH_CONNECTION: 926 pfd[j].fd = sockets[i].fd; 927 pfd[j].revents = 0; 928 /* XXX backoff when input buffer full */ 929 pfd[j].events = POLLIN; 930 if (sshbuf_len(sockets[i].output) > 0) 931 pfd[j].events |= POLLOUT; 932 j++; 933 break; 934 default: 935 break; 936 } 937 } 938 deadline = reaper(); 939 if (parent_alive_interval != 0) 940 deadline = (deadline == 0) ? parent_alive_interval : 941 MINIMUM(deadline, parent_alive_interval); 942 if (deadline == 0) { 943 *timeoutp = -1; /* INFTIM */ 944 } else { 945 if (deadline > INT_MAX / 1000) 946 *timeoutp = INT_MAX / 1000; 947 else 948 *timeoutp = deadline * 1000; 949 } 950 return (1); 951 } 952 953 static void 954 cleanup_socket(void) 955 { 956 if (cleanup_pid != 0 && getpid() != cleanup_pid) 957 return; 958 debug("%s: cleanup", __func__); 959 if (socket_name[0]) 960 unlink(socket_name); 961 if (socket_dir[0]) 962 rmdir(socket_dir); 963 } 964 965 void 966 cleanup_exit(int i) 967 { 968 cleanup_socket(); 969 _exit(i); 970 } 971 972 /*ARGSUSED*/ 973 __dead static void 974 cleanup_handler(int sig) 975 { 976 cleanup_socket(); 977 #ifdef ENABLE_PKCS11 978 pkcs11_terminate(); 979 #endif 980 _exit(2); 981 } 982 983 static void 984 check_parent_exists(void) 985 { 986 /* 987 * If our parent has exited then getppid() will return (pid_t)1, 988 * so testing for that should be safe. 989 */ 990 if (parent_pid != -1 && getppid() != parent_pid) { 991 /* printf("Parent has died - Authentication agent exiting.\n"); */ 992 cleanup_socket(); 993 _exit(2); 994 } 995 } 996 997 __dead static void 998 usage(void) 999 { 1000 fprintf(stderr, 1001 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1002 " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n" 1003 " ssh-agent [-c | -s] -k\n"); 1004 exit(1); 1005 } 1006 1007 static void 1008 csh_setenv(const char *name, const char *value) 1009 { 1010 printf("setenv %s %s;\n", name, value); 1011 } 1012 1013 static void 1014 csh_unsetenv(const char *name) 1015 { 1016 printf("unsetenv %s;\n", name); 1017 } 1018 1019 static void 1020 sh_setenv(const char *name, const char *value) 1021 { 1022 printf("%s=%s; export %s;\n", name, value, name); 1023 } 1024 1025 static void 1026 sh_unsetenv(const char *name) 1027 { 1028 printf("unset %s;\n", name); 1029 } 1030 int 1031 main(int ac, char **av) 1032 { 1033 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1034 int sock, fd, ch, result, saved_errno; 1035 char *shell, *pidstr, *agentsocket = NULL; 1036 struct rlimit rlim; 1037 void (*f_setenv)(const char *, const char *); 1038 void (*f_unsetenv)(const char *); 1039 extern int optind; 1040 extern char *optarg; 1041 pid_t pid; 1042 char pidstrbuf[1 + 3 * sizeof pid]; 1043 size_t len; 1044 mode_t prev_mask; 1045 int timeout = -1; /* INFTIM */ 1046 struct pollfd *pfd = NULL; 1047 size_t npfd = 0; 1048 1049 ssh_malloc_init(); /* must be called before any mallocs */ 1050 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1051 sanitise_stdfd(); 1052 1053 /* drop */ 1054 setegid(getgid()); 1055 setgid(getgid()); 1056 1057 #ifdef WITH_OPENSSL 1058 OpenSSL_add_all_algorithms(); 1059 #endif 1060 1061 while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) { 1062 switch (ch) { 1063 case 'E': 1064 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1065 if (fingerprint_hash == -1) 1066 fatal("Invalid hash algorithm \"%s\"", optarg); 1067 break; 1068 case 'c': 1069 if (s_flag) 1070 usage(); 1071 c_flag++; 1072 break; 1073 case 'k': 1074 k_flag++; 1075 break; 1076 case 'P': 1077 if (pkcs11_whitelist != NULL) 1078 fatal("-P option already specified"); 1079 pkcs11_whitelist = xstrdup(optarg); 1080 break; 1081 case 's': 1082 if (c_flag) 1083 usage(); 1084 s_flag++; 1085 break; 1086 case 'd': 1087 if (d_flag || D_flag) 1088 usage(); 1089 d_flag++; 1090 break; 1091 case 'D': 1092 if (d_flag || D_flag) 1093 usage(); 1094 D_flag++; 1095 break; 1096 case 'a': 1097 agentsocket = optarg; 1098 break; 1099 case 't': 1100 if ((lifetime = convtime(optarg)) == -1) { 1101 fprintf(stderr, "Invalid lifetime\n"); 1102 usage(); 1103 } 1104 break; 1105 default: 1106 usage(); 1107 } 1108 } 1109 ac -= optind; 1110 av += optind; 1111 1112 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1113 usage(); 1114 1115 if (pkcs11_whitelist == NULL) 1116 pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 1117 1118 if (ac == 0 && !c_flag && !s_flag) { 1119 shell = getenv("SHELL"); 1120 if (shell != NULL && (len = strlen(shell)) > 2 && 1121 strncmp(shell + len - 3, "csh", 3) == 0) 1122 c_flag = 1; 1123 } 1124 if (c_flag) { 1125 f_setenv = csh_setenv; 1126 f_unsetenv = csh_unsetenv; 1127 } else { 1128 f_setenv = sh_setenv; 1129 f_unsetenv = sh_unsetenv; 1130 } 1131 if (k_flag) { 1132 const char *errstr = NULL; 1133 1134 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1135 if (pidstr == NULL) { 1136 fprintf(stderr, "%s not set, cannot kill agent\n", 1137 SSH_AGENTPID_ENV_NAME); 1138 exit(1); 1139 } 1140 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1141 if (errstr) { 1142 fprintf(stderr, 1143 "%s=\"%s\", which is not a good PID: %s\n", 1144 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1145 exit(1); 1146 } 1147 if (kill(pid, SIGTERM) == -1) { 1148 perror("kill"); 1149 exit(1); 1150 } 1151 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 1152 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 1153 printf("echo Agent pid %ld killed;\n", (long)pid); 1154 exit(0); 1155 } 1156 parent_pid = getpid(); 1157 1158 if (agentsocket == NULL) { 1159 /* Create private directory for agent socket */ 1160 mktemp_proto(socket_dir, sizeof(socket_dir)); 1161 if (mkdtemp(socket_dir) == NULL) { 1162 perror("mkdtemp: private socket dir"); 1163 exit(1); 1164 } 1165 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1166 (long)parent_pid); 1167 } else { 1168 /* Try to use specified agent socket */ 1169 socket_dir[0] = '\0'; 1170 strlcpy(socket_name, agentsocket, sizeof socket_name); 1171 } 1172 1173 /* 1174 * Create socket early so it will exist before command gets run from 1175 * the parent. 1176 */ 1177 prev_mask = umask(0177); 1178 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1179 if (sock < 0) { 1180 /* XXX - unix_listener() calls error() not perror() */ 1181 *socket_name = '\0'; /* Don't unlink any existing file */ 1182 cleanup_exit(1); 1183 } 1184 umask(prev_mask); 1185 1186 /* 1187 * Fork, and have the parent execute the command, if any, or present 1188 * the socket data. The child continues as the authentication agent. 1189 */ 1190 if (D_flag || d_flag) { 1191 log_init(__progname, 1192 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1193 SYSLOG_FACILITY_AUTH, 1); 1194 if (c_flag) 1195 printf("setenv %s %s;\n", 1196 SSH_AUTHSOCKET_ENV_NAME, socket_name); 1197 else 1198 printf("%s=%s; export %s;\n", 1199 SSH_AUTHSOCKET_ENV_NAME, socket_name, 1200 SSH_AUTHSOCKET_ENV_NAME); 1201 printf("echo Agent pid %ld;\n", (long)parent_pid); 1202 fflush(stdout); 1203 goto skip; 1204 } 1205 pid = fork(); 1206 if (pid == -1) { 1207 perror("fork"); 1208 cleanup_exit(1); 1209 } 1210 if (pid != 0) { /* Parent - execute the given command. */ 1211 close(sock); 1212 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1213 if (ac == 0) { 1214 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 1215 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 1216 printf("echo Agent pid %ld;\n", (long)pid); 1217 exit(0); 1218 } 1219 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1220 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1221 perror("setenv"); 1222 exit(1); 1223 } 1224 execvp(av[0], av); 1225 perror(av[0]); 1226 exit(1); 1227 } 1228 /* child */ 1229 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1230 1231 if (setsid() == -1) { 1232 error("setsid: %s", strerror(errno)); 1233 cleanup_exit(1); 1234 } 1235 1236 (void)chdir("/"); 1237 1238 if (sock != STDERR_FILENO + 1) { 1239 if (dup2(sock, STDERR_FILENO + 1) == -1) { 1240 error("dup2: %s", strerror(errno)); 1241 cleanup_exit(1); 1242 } 1243 close(sock); 1244 sock = STDERR_FILENO + 1; 1245 } 1246 #if defined(F_CLOSEM) 1247 if (fcntl(sock + 1, F_CLOSEM, 0) == -1) { 1248 error("fcntl F_CLOSEM: %s", strerror(errno)); 1249 cleanup_exit(1); 1250 } 1251 #else 1252 { 1253 int nfiles; 1254 #if defined(_SC_OPEN_MAX) 1255 nfiles = sysconf(_SC_OPEN_MAX); 1256 #elif defined(RLIMIT_NOFILE) 1257 if (getrlimit(RLIMIT_CORE, &rlim) < 0) { 1258 error("getrlimit RLIMIT_NOFILE: %s", strerror(errno)); 1259 cleanup_exit(1); 1260 } 1261 nfiles = rlim.rlim_cur; 1262 #elif defined(OPEN_MAX) 1263 nfiles = OPEN_MAX; 1264 #elif defined(NOFILE) 1265 nfiles = NOFILE; 1266 #else 1267 nfiles = 1024; 1268 #endif 1269 for (fd = sock + 1; fd < nfiles; fd++) 1270 close(fd); 1271 } 1272 #endif 1273 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1274 if (dup2(fd, STDIN_FILENO) == -1 || 1275 dup2(fd, STDOUT_FILENO) == -1 || 1276 dup2(fd, STDERR_FILENO) == -1) { 1277 error("dup2: %s", strerror(errno)); 1278 cleanup_exit(1); 1279 } 1280 if (fd > STDERR_FILENO) 1281 close(fd); 1282 } 1283 1284 /* deny core dumps, since memory contains unencrypted private keys */ 1285 rlim.rlim_cur = rlim.rlim_max = 0; 1286 if (setrlimit(RLIMIT_CORE, &rlim) < 0) { 1287 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1288 cleanup_exit(1); 1289 } 1290 1291 skip: 1292 1293 cleanup_pid = getpid(); 1294 1295 #ifdef ENABLE_PKCS11 1296 pkcs11_init(0); 1297 #endif 1298 new_socket(AUTH_SOCKET, sock); 1299 if (ac > 0) 1300 parent_alive_interval = 10; 1301 idtab_init(); 1302 signal(SIGPIPE, SIG_IGN); 1303 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1304 signal(SIGHUP, cleanup_handler); 1305 signal(SIGTERM, cleanup_handler); 1306 1307 #ifdef __OpenBSD__ 1308 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1309 fatal("%s: pledge: %s", __progname, strerror(errno)); 1310 #endif 1311 1312 while (1) { 1313 prepare_poll(&pfd, &npfd, &timeout); 1314 result = poll(pfd, npfd, timeout); 1315 saved_errno = errno; 1316 if (parent_alive_interval != 0) 1317 check_parent_exists(); 1318 (void) reaper(); /* remove expired keys */ 1319 if (result < 0) { 1320 if (saved_errno == EINTR) 1321 continue; 1322 fatal("poll: %s", strerror(saved_errno)); 1323 } else if (result > 0) 1324 after_poll(pfd, npfd); 1325 } 1326 /* NOTREACHED */ 1327 } 1328