1 /* $OpenBSD: ssh-agent.c,v 1.276 2021/02/02 22:35:14 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 #include <sys/wait.h> 45 46 #ifdef WITH_OPENSSL 47 #include <openssl/evp.h> 48 #endif 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <paths.h> 53 #include <poll.h> 54 #include <signal.h> 55 #include <stdlib.h> 56 #include <stdio.h> 57 #include <string.h> 58 #include <stdarg.h> 59 #include <limits.h> 60 #include <time.h> 61 #include <unistd.h> 62 #include <util.h> 63 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh2.h" 67 #include "sshbuf.h" 68 #include "sshkey.h" 69 #include "authfd.h" 70 #include "compat.h" 71 #include "log.h" 72 #include "misc.h" 73 #include "digest.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "msg.h" 77 #include "ssherr.h" 78 #include "pathnames.h" 79 #include "ssh-pkcs11.h" 80 #include "sk-api.h" 81 82 #ifndef DEFAULT_ALLOWED_PROVIDERS 83 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 84 #endif 85 86 /* Maximum accepted message length */ 87 #define AGENT_MAX_LEN (256*1024) 88 /* Maximum bytes to read from client socket */ 89 #define AGENT_RBUF_LEN (4096) 90 91 typedef enum { 92 AUTH_UNUSED = 0, 93 AUTH_SOCKET = 1, 94 AUTH_CONNECTION = 2, 95 } sock_type; 96 97 typedef struct socket_entry { 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 char *sk_provider; 116 } Identity; 117 118 struct idtable { 119 int nentries; 120 TAILQ_HEAD(idqueue, identity) idlist; 121 }; 122 123 /* private key table */ 124 struct idtable *idtab; 125 126 int max_fd = 0; 127 128 /* pid of shell == parent of agent */ 129 pid_t parent_pid = -1; 130 time_t parent_alive_interval = 0; 131 132 /* pid of process for which cleanup_socket is applicable */ 133 pid_t cleanup_pid = 0; 134 135 /* pathname and directory for AUTH_SOCKET */ 136 char socket_name[PATH_MAX]; 137 char socket_dir[PATH_MAX]; 138 139 /* Pattern-list of allowed PKCS#11/Security key paths */ 140 static char *allowed_providers; 141 142 /* locking */ 143 #define LOCK_SIZE 32 144 #define LOCK_SALT_SIZE 16 145 #define LOCK_ROUNDS 1 146 int locked = 0; 147 u_char lock_pwhash[LOCK_SIZE]; 148 u_char lock_salt[LOCK_SALT_SIZE]; 149 150 extern char *__progname; 151 152 /* Default lifetime in seconds (0 == forever) */ 153 static int lifetime = 0; 154 155 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 156 157 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 158 static int restrict_websafe = 1; 159 160 static void 161 close_socket(SocketEntry *e) 162 { 163 close(e->fd); 164 sshbuf_free(e->input); 165 sshbuf_free(e->output); 166 sshbuf_free(e->request); 167 memset(e, '\0', sizeof(*e)); 168 e->fd = -1; 169 e->type = AUTH_UNUSED; 170 } 171 172 static void 173 idtab_init(void) 174 { 175 idtab = xcalloc(1, sizeof(*idtab)); 176 TAILQ_INIT(&idtab->idlist); 177 idtab->nentries = 0; 178 } 179 180 static void 181 free_identity(Identity *id) 182 { 183 sshkey_free(id->key); 184 free(id->provider); 185 free(id->comment); 186 free(id->sk_provider); 187 free(id); 188 } 189 190 /* return matching private key for given public key */ 191 static Identity * 192 lookup_identity(struct sshkey *key) 193 { 194 Identity *id; 195 196 TAILQ_FOREACH(id, &idtab->idlist, next) { 197 if (sshkey_equal(key, id->key)) 198 return (id); 199 } 200 return (NULL); 201 } 202 203 /* Check confirmation of keysign request */ 204 static int 205 confirm_key(Identity *id, const char *extra) 206 { 207 char *p; 208 int ret = -1; 209 210 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 211 if (p != NULL && 212 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 213 id->comment, p, 214 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 215 ret = 0; 216 free(p); 217 218 return (ret); 219 } 220 221 static void 222 send_status(SocketEntry *e, int success) 223 { 224 int r; 225 226 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 227 (r = sshbuf_put_u8(e->output, success ? 228 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 229 fatal_fr(r, "compose"); 230 } 231 232 /* send list of supported public keys to 'client' */ 233 static void 234 process_request_identities(SocketEntry *e) 235 { 236 Identity *id; 237 struct sshbuf *msg; 238 int r; 239 240 debug2_f("entering"); 241 242 if ((msg = sshbuf_new()) == NULL) 243 fatal_f("sshbuf_new failed"); 244 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 245 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 246 fatal_fr(r, "compose"); 247 TAILQ_FOREACH(id, &idtab->idlist, next) { 248 if ((r = sshkey_puts_opts(id->key, msg, SSHKEY_SERIALIZE_INFO)) 249 != 0 || 250 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 251 error_fr(r, "compose key/comment"); 252 continue; 253 } 254 } 255 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 256 fatal_fr(r, "enqueue"); 257 sshbuf_free(msg); 258 } 259 260 261 static char * 262 agent_decode_alg(struct sshkey *key, u_int flags) 263 { 264 if (key->type == KEY_RSA) { 265 if (flags & SSH_AGENT_RSA_SHA2_256) 266 return "rsa-sha2-256"; 267 else if (flags & SSH_AGENT_RSA_SHA2_512) 268 return "rsa-sha2-512"; 269 } else if (key->type == KEY_RSA_CERT) { 270 if (flags & SSH_AGENT_RSA_SHA2_256) 271 return "rsa-sha2-256-cert-v01@openssh.com"; 272 else if (flags & SSH_AGENT_RSA_SHA2_512) 273 return "rsa-sha2-512-cert-v01@openssh.com"; 274 } 275 return NULL; 276 } 277 278 /* 279 * Attempt to parse the contents of a buffer as a SSH publickey userauth 280 * request, checking its contents for consistency and matching the embedded 281 * key against the one that is being used for signing. 282 * Note: does not modify msg buffer. 283 * Optionally extract the username and session ID from the request. 284 */ 285 static int 286 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 287 char **userp, struct sshbuf **sess_idp) 288 { 289 struct sshbuf *b = NULL, *sess_id = NULL; 290 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 291 int r; 292 u_char t, sig_follows; 293 struct sshkey *mkey = NULL; 294 295 if (userp != NULL) 296 *userp = NULL; 297 if (sess_idp != NULL) 298 *sess_idp = NULL; 299 if ((b = sshbuf_fromb(msg)) == NULL) 300 fatal_f("sshbuf_fromb"); 301 302 /* SSH userauth request */ 303 if ((r = sshbuf_froms(b, &sess_id)) != 0) 304 goto out; 305 if (sshbuf_len(sess_id) == 0) { 306 r = SSH_ERR_INVALID_FORMAT; 307 goto out; 308 } 309 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 310 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 311 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 312 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 313 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 314 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 315 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 316 goto out; 317 if (t != SSH2_MSG_USERAUTH_REQUEST || 318 sig_follows != 1 || 319 strcmp(service, "ssh-connection") != 0 || 320 !sshkey_equal(expected_key, mkey) || 321 sshkey_type_from_name(pkalg) != expected_key->type) { 322 r = SSH_ERR_INVALID_FORMAT; 323 goto out; 324 } 325 if (strcmp(method, "publickey") != 0) { 326 r = SSH_ERR_INVALID_FORMAT; 327 goto out; 328 } 329 if (sshbuf_len(b) != 0) { 330 r = SSH_ERR_INVALID_FORMAT; 331 goto out; 332 } 333 /* success */ 334 r = 0; 335 debug3_f("well formed userauth"); 336 if (userp != NULL) { 337 *userp = user; 338 user = NULL; 339 } 340 if (sess_idp != NULL) { 341 *sess_idp = sess_id; 342 sess_id = NULL; 343 } 344 out: 345 sshbuf_free(b); 346 sshbuf_free(sess_id); 347 free(user); 348 free(service); 349 free(method); 350 free(pkalg); 351 sshkey_free(mkey); 352 return r; 353 } 354 355 /* 356 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 357 * Note: does not modify buffer. 358 */ 359 static int 360 parse_sshsig_request(struct sshbuf *msg) 361 { 362 int r; 363 struct sshbuf *b; 364 365 if ((b = sshbuf_fromb(msg)) == NULL) 366 fatal_f("sshbuf_fromb"); 367 368 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 369 (r = sshbuf_consume(b, 6)) != 0 || 370 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 371 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 372 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 373 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 374 goto out; 375 if (sshbuf_len(b) != 0) { 376 r = SSH_ERR_INVALID_FORMAT; 377 goto out; 378 } 379 /* success */ 380 r = 0; 381 out: 382 sshbuf_free(b); 383 return r; 384 } 385 386 /* 387 * This function inspects a message to be signed by a FIDO key that has a 388 * web-like application string (i.e. one that does not begin with "ssh:". 389 * It checks that the message is one of those expected for SSH operations 390 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 391 * for the web. 392 */ 393 static int 394 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 395 { 396 if (parse_userauth_request(data, key, NULL, NULL) == 0) { 397 debug_f("signed data matches public key userauth request"); 398 return 1; 399 } 400 if (parse_sshsig_request(data) == 0) { 401 debug_f("signed data matches SSHSIG signature request"); 402 return 1; 403 } 404 405 /* XXX check CA signature operation */ 406 407 error("web-origin key attempting to sign non-SSH message"); 408 return 0; 409 } 410 411 /* ssh2 only */ 412 static void 413 process_sign_request2(SocketEntry *e) 414 { 415 u_char *signature = NULL; 416 size_t slen = 0; 417 u_int compat = 0, flags; 418 int r, ok = -1; 419 char *fp = NULL; 420 struct sshbuf *msg = NULL, *data = NULL; 421 struct sshkey *key = NULL; 422 struct identity *id; 423 struct notifier_ctx *notifier = NULL; 424 425 debug_f("entering"); 426 427 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 428 fatal_f("sshbuf_new failed"); 429 if ((r = sshkey_froms(e->request, &key)) != 0 || 430 (r = sshbuf_get_stringb(e->request, data)) != 0 || 431 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 432 error_fr(r, "parse"); 433 goto send; 434 } 435 436 if ((id = lookup_identity(key)) == NULL) { 437 verbose_f("%s key not found", sshkey_type(key)); 438 goto send; 439 } 440 if (id->confirm && confirm_key(id, NULL) != 0) { 441 verbose_f("user refused key"); 442 goto send; 443 } 444 if (sshkey_is_sk(id->key)) { 445 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 446 !check_websafe_message_contents(key, data)) { 447 /* error already logged */ 448 goto send; 449 } 450 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 451 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 452 SSH_FP_DEFAULT)) == NULL) 453 fatal_f("fingerprint failed"); 454 notifier = notify_start(0, 455 "Confirm user presence for key %s %s", 456 sshkey_type(id->key), fp); 457 } 458 } 459 /* XXX support PIN required FIDO keys */ 460 if ((r = sshkey_sign(id->key, &signature, &slen, 461 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 462 id->sk_provider, NULL, compat)) != 0) { 463 error_fr(r, "sshkey_sign"); 464 goto send; 465 } 466 /* Success */ 467 ok = 0; 468 send: 469 notify_complete(notifier, "User presence confirmed"); 470 471 if (ok == 0) { 472 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 473 (r = sshbuf_put_string(msg, signature, slen)) != 0) 474 fatal_fr(r, "compose"); 475 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 476 fatal_fr(r, "compose failure"); 477 478 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 479 fatal_fr(r, "enqueue"); 480 481 sshbuf_free(data); 482 sshbuf_free(msg); 483 sshkey_free(key); 484 free(fp); 485 free(signature); 486 } 487 488 /* shared */ 489 static void 490 process_remove_identity(SocketEntry *e) 491 { 492 int r, success = 0; 493 struct sshkey *key = NULL; 494 Identity *id; 495 496 debug2_f("entering"); 497 if ((r = sshkey_froms(e->request, &key)) != 0) { 498 error_fr(r, "parse key"); 499 goto done; 500 } 501 if ((id = lookup_identity(key)) == NULL) { 502 debug_f("key not found"); 503 goto done; 504 } 505 /* We have this key, free it. */ 506 if (idtab->nentries < 1) 507 fatal_f("internal error: nentries %d", idtab->nentries); 508 TAILQ_REMOVE(&idtab->idlist, id, next); 509 free_identity(id); 510 idtab->nentries--; 511 success = 1; 512 done: 513 sshkey_free(key); 514 send_status(e, success); 515 } 516 517 static void 518 process_remove_all_identities(SocketEntry *e) 519 { 520 Identity *id; 521 522 debug2_f("entering"); 523 /* Loop over all identities and clear the keys. */ 524 for (id = TAILQ_FIRST(&idtab->idlist); id; 525 id = TAILQ_FIRST(&idtab->idlist)) { 526 TAILQ_REMOVE(&idtab->idlist, id, next); 527 free_identity(id); 528 } 529 530 /* Mark that there are no identities. */ 531 idtab->nentries = 0; 532 533 /* Send success. */ 534 send_status(e, 1); 535 } 536 537 /* removes expired keys and returns number of seconds until the next expiry */ 538 static time_t 539 reaper(void) 540 { 541 time_t deadline = 0, now = monotime(); 542 Identity *id, *nxt; 543 544 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 545 nxt = TAILQ_NEXT(id, next); 546 if (id->death == 0) 547 continue; 548 if (now >= id->death) { 549 debug("expiring key '%s'", id->comment); 550 TAILQ_REMOVE(&idtab->idlist, id, next); 551 free_identity(id); 552 idtab->nentries--; 553 } else 554 deadline = (deadline == 0) ? id->death : 555 MINIMUM(deadline, id->death); 556 } 557 if (deadline == 0 || deadline <= now) 558 return 0; 559 else 560 return (deadline - now); 561 } 562 563 static int 564 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 565 u_int *secondsp, int *confirmp, char **sk_providerp) 566 { 567 u_char ctype; 568 int r; 569 u_int seconds, maxsign = 0; 570 char *ext_name = NULL; 571 struct sshbuf *b = NULL; 572 573 while (sshbuf_len(m)) { 574 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 575 error_fr(r, "parse constraint type"); 576 goto err; 577 } 578 switch (ctype) { 579 case SSH_AGENT_CONSTRAIN_LIFETIME: 580 if (*deathp != 0) { 581 error_f("lifetime already set"); 582 goto err; 583 } 584 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 585 error_fr(r, "parse lifetime constraint"); 586 goto err; 587 } 588 *deathp = monotime() + seconds; 589 *secondsp = seconds; 590 break; 591 case SSH_AGENT_CONSTRAIN_CONFIRM: 592 if (*confirmp != 0) { 593 error_f("confirm already set"); 594 goto err; 595 } 596 *confirmp = 1; 597 break; 598 case SSH_AGENT_CONSTRAIN_MAXSIGN: 599 if (k == NULL) { 600 error_f("maxsign not valid here"); 601 goto err; 602 } 603 if (maxsign != 0) { 604 error_f("maxsign already set"); 605 goto err; 606 } 607 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 608 error_fr(r, "parse maxsign constraint"); 609 goto err; 610 } 611 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 612 error_fr(r, "enable maxsign"); 613 goto err; 614 } 615 break; 616 case SSH_AGENT_CONSTRAIN_EXTENSION: 617 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 618 error_fr(r, "parse constraint extension"); 619 goto err; 620 } 621 debug_f("constraint ext %s", ext_name); 622 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 623 if (sk_providerp == NULL) { 624 error_f("%s not valid here", ext_name); 625 goto err; 626 } 627 if (*sk_providerp != NULL) { 628 error_f("%s already set", ext_name); 629 goto err; 630 } 631 if ((r = sshbuf_get_cstring(m, 632 sk_providerp, NULL)) != 0) { 633 error_fr(r, "parse %s", ext_name); 634 goto err; 635 } 636 } else { 637 error_f("unsupported constraint \"%s\"", 638 ext_name); 639 goto err; 640 } 641 free(ext_name); 642 break; 643 default: 644 error_f("Unknown constraint %d", ctype); 645 err: 646 free(ext_name); 647 sshbuf_free(b); 648 return -1; 649 } 650 } 651 /* success */ 652 return 0; 653 } 654 655 static void 656 process_add_identity(SocketEntry *e) 657 { 658 Identity *id; 659 int success = 0, confirm = 0; 660 char *fp, *comment = NULL, *sk_provider = NULL; 661 char canonical_provider[PATH_MAX]; 662 time_t death = 0; 663 u_int seconds = 0; 664 struct sshkey *k = NULL; 665 int r = SSH_ERR_INTERNAL_ERROR; 666 667 debug2_f("entering"); 668 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 669 k == NULL || 670 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 671 error_fr(r, "parse"); 672 goto out; 673 } 674 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 675 &sk_provider) != 0) { 676 error_f("failed to parse constraints"); 677 sshbuf_reset(e->request); 678 goto out; 679 } 680 681 if (sk_provider != NULL) { 682 if (!sshkey_is_sk(k)) { 683 error("Cannot add provider: %s is not an " 684 "authenticator-hosted key", sshkey_type(k)); 685 goto out; 686 } 687 if (strcasecmp(sk_provider, "internal") == 0) { 688 debug_f("internal provider"); 689 } else { 690 if (realpath(sk_provider, canonical_provider) == NULL) { 691 verbose("failed provider \"%.100s\": " 692 "realpath: %s", sk_provider, 693 strerror(errno)); 694 goto out; 695 } 696 free(sk_provider); 697 sk_provider = xstrdup(canonical_provider); 698 if (match_pattern_list(sk_provider, 699 allowed_providers, 0) != 1) { 700 error("Refusing add key: " 701 "provider %s not allowed", sk_provider); 702 goto out; 703 } 704 } 705 } 706 if ((r = sshkey_shield_private(k)) != 0) { 707 error_fr(r, "shield private"); 708 goto out; 709 } 710 if (lifetime && !death) 711 death = monotime() + lifetime; 712 if ((id = lookup_identity(k)) == NULL) { 713 id = xcalloc(1, sizeof(Identity)); 714 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 715 /* Increment the number of identities. */ 716 idtab->nentries++; 717 } else { 718 /* key state might have been updated */ 719 sshkey_free(id->key); 720 free(id->comment); 721 free(id->sk_provider); 722 } 723 /* success */ 724 id->key = k; 725 id->comment = comment; 726 id->death = death; 727 id->confirm = confirm; 728 id->sk_provider = sk_provider; 729 730 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 731 SSH_FP_DEFAULT)) == NULL) 732 fatal_f("sshkey_fingerprint failed"); 733 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 734 "(provider: %s)", sshkey_ssh_name(k), fp, comment, seconds, 735 confirm, sk_provider == NULL ? "none" : sk_provider); 736 free(fp); 737 /* transferred */ 738 k = NULL; 739 comment = NULL; 740 sk_provider = NULL; 741 success = 1; 742 out: 743 free(sk_provider); 744 free(comment); 745 sshkey_free(k); 746 send_status(e, success); 747 } 748 749 /* XXX todo: encrypt sensitive data with passphrase */ 750 static void 751 process_lock_agent(SocketEntry *e, int lock) 752 { 753 int r, success = 0, delay; 754 char *passwd; 755 u_char passwdhash[LOCK_SIZE]; 756 static u_int fail_count = 0; 757 size_t pwlen; 758 759 debug2_f("entering"); 760 /* 761 * This is deliberately fatal: the user has requested that we lock, 762 * but we can't parse their request properly. The only safe thing to 763 * do is abort. 764 */ 765 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 766 fatal_fr(r, "parse"); 767 if (pwlen == 0) { 768 debug("empty password not supported"); 769 } else if (locked && !lock) { 770 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 771 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 772 fatal("bcrypt_pbkdf"); 773 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 774 debug("agent unlocked"); 775 locked = 0; 776 fail_count = 0; 777 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 778 success = 1; 779 } else { 780 /* delay in 0.1s increments up to 10s */ 781 if (fail_count < 100) 782 fail_count++; 783 delay = 100000 * fail_count; 784 debug("unlock failed, delaying %0.1lf seconds", 785 (double)delay/1000000); 786 usleep(delay); 787 } 788 explicit_bzero(passwdhash, sizeof(passwdhash)); 789 } else if (!locked && lock) { 790 debug("agent locked"); 791 locked = 1; 792 arc4random_buf(lock_salt, sizeof(lock_salt)); 793 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 794 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 795 fatal("bcrypt_pbkdf"); 796 success = 1; 797 } 798 freezero(passwd, pwlen); 799 send_status(e, success); 800 } 801 802 static void 803 no_identities(SocketEntry *e) 804 { 805 struct sshbuf *msg; 806 int r; 807 808 if ((msg = sshbuf_new()) == NULL) 809 fatal_f("sshbuf_new failed"); 810 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 811 (r = sshbuf_put_u32(msg, 0)) != 0 || 812 (r = sshbuf_put_stringb(e->output, msg)) != 0) 813 fatal_fr(r, "compose"); 814 sshbuf_free(msg); 815 } 816 817 #ifdef ENABLE_PKCS11 818 static void 819 process_add_smartcard_key(SocketEntry *e) 820 { 821 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 822 char **comments = NULL; 823 int r, i, count = 0, success = 0, confirm = 0; 824 u_int seconds = 0; 825 time_t death = 0; 826 struct sshkey **keys = NULL, *k; 827 Identity *id; 828 829 debug2_f("entering"); 830 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 831 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 832 error_fr(r, "parse"); 833 goto send; 834 } 835 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 836 NULL) != 0) { 837 error_f("failed to parse constraints"); 838 goto send; 839 } 840 if (realpath(provider, canonical_provider) == NULL) { 841 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 842 provider, strerror(errno)); 843 goto send; 844 } 845 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 846 verbose("refusing PKCS#11 add of \"%.100s\": " 847 "provider not allowed", canonical_provider); 848 goto send; 849 } 850 debug_f("add %.100s", canonical_provider); 851 if (lifetime && !death) 852 death = monotime() + lifetime; 853 854 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 855 for (i = 0; i < count; i++) { 856 k = keys[i]; 857 if (lookup_identity(k) == NULL) { 858 id = xcalloc(1, sizeof(Identity)); 859 id->key = k; 860 keys[i] = NULL; /* transferred */ 861 id->provider = xstrdup(canonical_provider); 862 if (*comments[i] != '\0') { 863 id->comment = comments[i]; 864 comments[i] = NULL; /* transferred */ 865 } else { 866 id->comment = xstrdup(canonical_provider); 867 } 868 id->death = death; 869 id->confirm = confirm; 870 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 871 idtab->nentries++; 872 success = 1; 873 } 874 /* XXX update constraints for existing keys */ 875 sshkey_free(keys[i]); 876 free(comments[i]); 877 } 878 send: 879 free(pin); 880 free(provider); 881 free(keys); 882 free(comments); 883 send_status(e, success); 884 } 885 886 static void 887 process_remove_smartcard_key(SocketEntry *e) 888 { 889 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 890 int r, success = 0; 891 Identity *id, *nxt; 892 893 debug2_f("entering"); 894 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 895 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 896 error_fr(r, "parse"); 897 goto send; 898 } 899 free(pin); 900 901 if (realpath(provider, canonical_provider) == NULL) { 902 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 903 provider, strerror(errno)); 904 goto send; 905 } 906 907 debug_f("remove %.100s", canonical_provider); 908 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 909 nxt = TAILQ_NEXT(id, next); 910 /* Skip file--based keys */ 911 if (id->provider == NULL) 912 continue; 913 if (!strcmp(canonical_provider, id->provider)) { 914 TAILQ_REMOVE(&idtab->idlist, id, next); 915 free_identity(id); 916 idtab->nentries--; 917 } 918 } 919 if (pkcs11_del_provider(canonical_provider) == 0) 920 success = 1; 921 else 922 error_f("pkcs11_del_provider failed"); 923 send: 924 free(provider); 925 send_status(e, success); 926 } 927 #endif /* ENABLE_PKCS11 */ 928 929 /* 930 * dispatch incoming message. 931 * returns 1 on success, 0 for incomplete messages or -1 on error. 932 */ 933 static int 934 process_message(u_int socknum) 935 { 936 u_int msg_len; 937 u_char type; 938 const u_char *cp; 939 int r; 940 SocketEntry *e; 941 942 if (socknum >= sockets_alloc) 943 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 944 e = &sockets[socknum]; 945 946 if (sshbuf_len(e->input) < 5) 947 return 0; /* Incomplete message header. */ 948 cp = sshbuf_ptr(e->input); 949 msg_len = PEEK_U32(cp); 950 if (msg_len > AGENT_MAX_LEN) { 951 debug_f("socket %u (fd=%d) message too long %u > %u", 952 socknum, e->fd, msg_len, AGENT_MAX_LEN); 953 return -1; 954 } 955 if (sshbuf_len(e->input) < msg_len + 4) 956 return 0; /* Incomplete message body. */ 957 958 /* move the current input to e->request */ 959 sshbuf_reset(e->request); 960 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 961 (r = sshbuf_get_u8(e->request, &type)) != 0) { 962 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 963 r == SSH_ERR_STRING_TOO_LARGE) { 964 error_fr(r, "parse"); 965 return -1; 966 } 967 fatal_fr(r, "parse"); 968 } 969 970 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 971 972 /* check whether agent is locked */ 973 if (locked && type != SSH_AGENTC_UNLOCK) { 974 sshbuf_reset(e->request); 975 switch (type) { 976 case SSH2_AGENTC_REQUEST_IDENTITIES: 977 /* send empty lists */ 978 no_identities(e); 979 break; 980 default: 981 /* send a fail message for all other request types */ 982 send_status(e, 0); 983 } 984 return 1; 985 } 986 987 switch (type) { 988 case SSH_AGENTC_LOCK: 989 case SSH_AGENTC_UNLOCK: 990 process_lock_agent(e, type == SSH_AGENTC_LOCK); 991 break; 992 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 993 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 994 break; 995 /* ssh2 */ 996 case SSH2_AGENTC_SIGN_REQUEST: 997 process_sign_request2(e); 998 break; 999 case SSH2_AGENTC_REQUEST_IDENTITIES: 1000 process_request_identities(e); 1001 break; 1002 case SSH2_AGENTC_ADD_IDENTITY: 1003 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1004 process_add_identity(e); 1005 break; 1006 case SSH2_AGENTC_REMOVE_IDENTITY: 1007 process_remove_identity(e); 1008 break; 1009 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1010 process_remove_all_identities(e); 1011 break; 1012 #ifdef ENABLE_PKCS11 1013 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1014 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1015 process_add_smartcard_key(e); 1016 break; 1017 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1018 process_remove_smartcard_key(e); 1019 break; 1020 #endif /* ENABLE_PKCS11 */ 1021 default: 1022 /* Unknown message. Respond with failure. */ 1023 error("Unknown message %d", type); 1024 sshbuf_reset(e->request); 1025 send_status(e, 0); 1026 break; 1027 } 1028 return 1; 1029 } 1030 1031 static void 1032 new_socket(sock_type type, int fd) 1033 { 1034 u_int i, old_alloc, new_alloc; 1035 1036 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1037 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1038 set_nonblock(fd); 1039 1040 if (fd > max_fd) 1041 max_fd = fd; 1042 1043 for (i = 0; i < sockets_alloc; i++) 1044 if (sockets[i].type == AUTH_UNUSED) { 1045 sockets[i].fd = fd; 1046 if ((sockets[i].input = sshbuf_new()) == NULL || 1047 (sockets[i].output = sshbuf_new()) == NULL || 1048 (sockets[i].request = sshbuf_new()) == NULL) 1049 fatal_f("sshbuf_new failed"); 1050 sockets[i].type = type; 1051 return; 1052 } 1053 old_alloc = sockets_alloc; 1054 new_alloc = sockets_alloc + 10; 1055 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1056 sizeof(sockets[0])); 1057 for (i = old_alloc; i < new_alloc; i++) 1058 sockets[i].type = AUTH_UNUSED; 1059 sockets_alloc = new_alloc; 1060 sockets[old_alloc].fd = fd; 1061 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1062 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1063 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1064 fatal_f("sshbuf_new failed"); 1065 sockets[old_alloc].type = type; 1066 } 1067 1068 static int 1069 handle_socket_read(u_int socknum) 1070 { 1071 struct sockaddr_un sunaddr; 1072 socklen_t slen; 1073 uid_t euid; 1074 gid_t egid; 1075 int fd; 1076 1077 slen = sizeof(sunaddr); 1078 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1079 if (fd == -1) { 1080 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1081 return -1; 1082 } 1083 if (getpeereid(fd, &euid, &egid) == -1) { 1084 error("getpeereid %d failed: %s", fd, strerror(errno)); 1085 close(fd); 1086 return -1; 1087 } 1088 if ((euid != 0) && (getuid() != euid)) { 1089 error("uid mismatch: peer euid %u != uid %u", 1090 (u_int) euid, (u_int) getuid()); 1091 close(fd); 1092 return -1; 1093 } 1094 new_socket(AUTH_CONNECTION, fd); 1095 return 0; 1096 } 1097 1098 static int 1099 handle_conn_read(u_int socknum) 1100 { 1101 char buf[AGENT_RBUF_LEN]; 1102 ssize_t len; 1103 int r; 1104 1105 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1106 if (len == -1) { 1107 if (errno == EAGAIN || errno == EINTR) 1108 return 0; 1109 error_f("read error on socket %u (fd %d): %s", 1110 socknum, sockets[socknum].fd, strerror(errno)); 1111 } 1112 return -1; 1113 } 1114 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1115 fatal_fr(r, "compose"); 1116 explicit_bzero(buf, sizeof(buf)); 1117 for (;;) { 1118 if ((r = process_message(socknum)) == -1) 1119 return -1; 1120 else if (r == 0) 1121 break; 1122 } 1123 return 0; 1124 } 1125 1126 static int 1127 handle_conn_write(u_int socknum) 1128 { 1129 ssize_t len; 1130 int r; 1131 1132 if (sshbuf_len(sockets[socknum].output) == 0) 1133 return 0; /* shouldn't happen */ 1134 if ((len = write(sockets[socknum].fd, 1135 sshbuf_ptr(sockets[socknum].output), 1136 sshbuf_len(sockets[socknum].output))) <= 0) { 1137 if (len == -1) { 1138 if (errno == EAGAIN || errno == EINTR) 1139 return 0; 1140 error_f("read error on socket %u (fd %d): %s", 1141 socknum, sockets[socknum].fd, strerror(errno)); 1142 } 1143 return -1; 1144 } 1145 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1146 fatal_fr(r, "consume"); 1147 return 0; 1148 } 1149 1150 static void 1151 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1152 { 1153 size_t i; 1154 u_int socknum, activefds = npfd; 1155 1156 for (i = 0; i < npfd; i++) { 1157 if (pfd[i].revents == 0) 1158 continue; 1159 /* Find sockets entry */ 1160 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1161 if (sockets[socknum].type != AUTH_SOCKET && 1162 sockets[socknum].type != AUTH_CONNECTION) 1163 continue; 1164 if (pfd[i].fd == sockets[socknum].fd) 1165 break; 1166 } 1167 if (socknum >= sockets_alloc) { 1168 error_f("no socket for fd %d", pfd[i].fd); 1169 continue; 1170 } 1171 /* Process events */ 1172 switch (sockets[socknum].type) { 1173 case AUTH_SOCKET: 1174 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1175 break; 1176 if (npfd > maxfds) { 1177 debug3("out of fds (active %u >= limit %u); " 1178 "skipping accept", activefds, maxfds); 1179 break; 1180 } 1181 if (handle_socket_read(socknum) == 0) 1182 activefds++; 1183 break; 1184 case AUTH_CONNECTION: 1185 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1186 handle_conn_read(socknum) != 0) { 1187 goto close_sock; 1188 } 1189 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1190 handle_conn_write(socknum) != 0) { 1191 close_sock: 1192 if (activefds == 0) 1193 fatal("activefds == 0 at close_sock"); 1194 close_socket(&sockets[socknum]); 1195 activefds--; 1196 break; 1197 } 1198 break; 1199 default: 1200 break; 1201 } 1202 } 1203 } 1204 1205 static int 1206 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1207 { 1208 struct pollfd *pfd = *pfdp; 1209 size_t i, j, npfd = 0; 1210 time_t deadline; 1211 int r; 1212 1213 /* Count active sockets */ 1214 for (i = 0; i < sockets_alloc; i++) { 1215 switch (sockets[i].type) { 1216 case AUTH_SOCKET: 1217 case AUTH_CONNECTION: 1218 npfd++; 1219 break; 1220 case AUTH_UNUSED: 1221 break; 1222 default: 1223 fatal("Unknown socket type %d", sockets[i].type); 1224 break; 1225 } 1226 } 1227 if (npfd != *npfdp && 1228 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1229 fatal_f("recallocarray failed"); 1230 *pfdp = pfd; 1231 *npfdp = npfd; 1232 1233 for (i = j = 0; i < sockets_alloc; i++) { 1234 switch (sockets[i].type) { 1235 case AUTH_SOCKET: 1236 if (npfd > maxfds) { 1237 debug3("out of fds (active %zu >= limit %u); " 1238 "skipping arming listener", npfd, maxfds); 1239 break; 1240 } 1241 pfd[j].fd = sockets[i].fd; 1242 pfd[j].revents = 0; 1243 pfd[j].events = POLLIN; 1244 j++; 1245 break; 1246 case AUTH_CONNECTION: 1247 pfd[j].fd = sockets[i].fd; 1248 pfd[j].revents = 0; 1249 /* 1250 * Only prepare to read if we can handle a full-size 1251 * input read buffer and enqueue a max size reply.. 1252 */ 1253 if ((r = sshbuf_check_reserve(sockets[i].input, 1254 AGENT_RBUF_LEN)) == 0 && 1255 (r = sshbuf_check_reserve(sockets[i].output, 1256 AGENT_MAX_LEN)) == 0) 1257 pfd[j].events = POLLIN; 1258 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1259 fatal_fr(r, "reserve"); 1260 if (sshbuf_len(sockets[i].output) > 0) 1261 pfd[j].events |= POLLOUT; 1262 j++; 1263 break; 1264 default: 1265 break; 1266 } 1267 } 1268 deadline = reaper(); 1269 if (parent_alive_interval != 0) 1270 deadline = (deadline == 0) ? parent_alive_interval : 1271 MINIMUM(deadline, parent_alive_interval); 1272 if (deadline == 0) { 1273 *timeoutp = -1; /* INFTIM */ 1274 } else { 1275 if (deadline > INT_MAX / 1000) 1276 *timeoutp = INT_MAX / 1000; 1277 else 1278 *timeoutp = deadline * 1000; 1279 } 1280 return (1); 1281 } 1282 1283 static void 1284 cleanup_socket(void) 1285 { 1286 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1287 return; 1288 debug_f("cleanup"); 1289 if (socket_name[0]) 1290 unlink(socket_name); 1291 if (socket_dir[0]) 1292 rmdir(socket_dir); 1293 } 1294 1295 void 1296 cleanup_exit(int i) 1297 { 1298 cleanup_socket(); 1299 _exit(i); 1300 } 1301 1302 /*ARGSUSED*/ 1303 static void 1304 cleanup_handler(int sig) 1305 { 1306 cleanup_socket(); 1307 #ifdef ENABLE_PKCS11 1308 pkcs11_terminate(); 1309 #endif 1310 _exit(2); 1311 } 1312 1313 static void 1314 check_parent_exists(void) 1315 { 1316 /* 1317 * If our parent has exited then getppid() will return (pid_t)1, 1318 * so testing for that should be safe. 1319 */ 1320 if (parent_pid != -1 && getppid() != parent_pid) { 1321 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1322 cleanup_socket(); 1323 _exit(2); 1324 } 1325 } 1326 1327 static void 1328 usage(void) 1329 { 1330 fprintf(stderr, 1331 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1332 " [-P allowed_providers] [-t life]\n" 1333 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1334 " [-t life] command [arg ...]\n" 1335 " ssh-agent [-c | -s] -k\n"); 1336 exit(1); 1337 } 1338 1339 int 1340 main(int ac, char **av) 1341 { 1342 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1343 int sock, ch, result, saved_errno; 1344 char *shell, *format, *pidstr, *agentsocket = NULL; 1345 struct rlimit rlim; 1346 extern int optind; 1347 extern char *optarg; 1348 pid_t pid; 1349 char pidstrbuf[1 + 3 * sizeof pid]; 1350 size_t len; 1351 mode_t prev_mask; 1352 int timeout = -1; /* INFTIM */ 1353 struct pollfd *pfd = NULL; 1354 size_t npfd = 0; 1355 u_int maxfds; 1356 1357 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1358 sanitise_stdfd(); 1359 1360 /* drop */ 1361 setegid(getgid()); 1362 setgid(getgid()); 1363 1364 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1365 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1366 1367 #ifdef WITH_OPENSSL 1368 OpenSSL_add_all_algorithms(); 1369 #endif 1370 1371 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1372 switch (ch) { 1373 case 'E': 1374 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1375 if (fingerprint_hash == -1) 1376 fatal("Invalid hash algorithm \"%s\"", optarg); 1377 break; 1378 case 'c': 1379 if (s_flag) 1380 usage(); 1381 c_flag++; 1382 break; 1383 case 'k': 1384 k_flag++; 1385 break; 1386 case 'O': 1387 if (strcmp(optarg, "no-restrict-websafe") == 0) 1388 restrict_websafe = 0; 1389 else 1390 fatal("Unknown -O option"); 1391 break; 1392 case 'P': 1393 if (allowed_providers != NULL) 1394 fatal("-P option already specified"); 1395 allowed_providers = xstrdup(optarg); 1396 break; 1397 case 's': 1398 if (c_flag) 1399 usage(); 1400 s_flag++; 1401 break; 1402 case 'd': 1403 if (d_flag || D_flag) 1404 usage(); 1405 d_flag++; 1406 break; 1407 case 'D': 1408 if (d_flag || D_flag) 1409 usage(); 1410 D_flag++; 1411 break; 1412 case 'a': 1413 agentsocket = optarg; 1414 break; 1415 case 't': 1416 if ((lifetime = convtime(optarg)) == -1) { 1417 fprintf(stderr, "Invalid lifetime\n"); 1418 usage(); 1419 } 1420 break; 1421 default: 1422 usage(); 1423 } 1424 } 1425 ac -= optind; 1426 av += optind; 1427 1428 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1429 usage(); 1430 1431 if (allowed_providers == NULL) 1432 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1433 1434 if (ac == 0 && !c_flag && !s_flag) { 1435 shell = getenv("SHELL"); 1436 if (shell != NULL && (len = strlen(shell)) > 2 && 1437 strncmp(shell + len - 3, "csh", 3) == 0) 1438 c_flag = 1; 1439 } 1440 if (k_flag) { 1441 const char *errstr = NULL; 1442 1443 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1444 if (pidstr == NULL) { 1445 fprintf(stderr, "%s not set, cannot kill agent\n", 1446 SSH_AGENTPID_ENV_NAME); 1447 exit(1); 1448 } 1449 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1450 if (errstr) { 1451 fprintf(stderr, 1452 "%s=\"%s\", which is not a good PID: %s\n", 1453 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1454 exit(1); 1455 } 1456 if (kill(pid, SIGTERM) == -1) { 1457 perror("kill"); 1458 exit(1); 1459 } 1460 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1461 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1462 printf(format, SSH_AGENTPID_ENV_NAME); 1463 printf("echo Agent pid %ld killed;\n", (long)pid); 1464 exit(0); 1465 } 1466 1467 /* 1468 * Minimum file descriptors: 1469 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1470 * a few spare for libc / stack protectors / sanitisers, etc. 1471 */ 1472 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1473 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1474 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1475 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1476 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1477 1478 parent_pid = getpid(); 1479 1480 if (agentsocket == NULL) { 1481 /* Create private directory for agent socket */ 1482 mktemp_proto(socket_dir, sizeof(socket_dir)); 1483 if (mkdtemp(socket_dir) == NULL) { 1484 perror("mkdtemp: private socket dir"); 1485 exit(1); 1486 } 1487 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1488 (long)parent_pid); 1489 } else { 1490 /* Try to use specified agent socket */ 1491 socket_dir[0] = '\0'; 1492 strlcpy(socket_name, agentsocket, sizeof socket_name); 1493 } 1494 1495 /* 1496 * Create socket early so it will exist before command gets run from 1497 * the parent. 1498 */ 1499 prev_mask = umask(0177); 1500 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1501 if (sock < 0) { 1502 /* XXX - unix_listener() calls error() not perror() */ 1503 *socket_name = '\0'; /* Don't unlink any existing file */ 1504 cleanup_exit(1); 1505 } 1506 umask(prev_mask); 1507 1508 /* 1509 * Fork, and have the parent execute the command, if any, or present 1510 * the socket data. The child continues as the authentication agent. 1511 */ 1512 if (D_flag || d_flag) { 1513 log_init(__progname, 1514 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1515 SYSLOG_FACILITY_AUTH, 1); 1516 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1517 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1518 SSH_AUTHSOCKET_ENV_NAME); 1519 printf("echo Agent pid %ld;\n", (long)parent_pid); 1520 fflush(stdout); 1521 goto skip; 1522 } 1523 pid = fork(); 1524 if (pid == -1) { 1525 perror("fork"); 1526 cleanup_exit(1); 1527 } 1528 if (pid != 0) { /* Parent - execute the given command. */ 1529 close(sock); 1530 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1531 if (ac == 0) { 1532 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1533 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1534 SSH_AUTHSOCKET_ENV_NAME); 1535 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1536 SSH_AGENTPID_ENV_NAME); 1537 printf("echo Agent pid %ld;\n", (long)pid); 1538 exit(0); 1539 } 1540 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1541 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1542 perror("setenv"); 1543 exit(1); 1544 } 1545 execvp(av[0], av); 1546 perror(av[0]); 1547 exit(1); 1548 } 1549 /* child */ 1550 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1551 1552 if (setsid() == -1) { 1553 error("setsid: %s", strerror(errno)); 1554 cleanup_exit(1); 1555 } 1556 1557 (void)chdir("/"); 1558 if (stdfd_devnull(1, 1, 1) == -1) 1559 error_f("stdfd_devnull failed"); 1560 1561 /* deny core dumps, since memory contains unencrypted private keys */ 1562 rlim.rlim_cur = rlim.rlim_max = 0; 1563 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1564 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1565 cleanup_exit(1); 1566 } 1567 1568 skip: 1569 1570 cleanup_pid = getpid(); 1571 1572 #ifdef ENABLE_PKCS11 1573 pkcs11_init(0); 1574 #endif 1575 new_socket(AUTH_SOCKET, sock); 1576 if (ac > 0) 1577 parent_alive_interval = 10; 1578 idtab_init(); 1579 ssh_signal(SIGPIPE, SIG_IGN); 1580 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1581 ssh_signal(SIGHUP, cleanup_handler); 1582 ssh_signal(SIGTERM, cleanup_handler); 1583 1584 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1585 fatal("%s: pledge: %s", __progname, strerror(errno)); 1586 1587 while (1) { 1588 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1589 result = poll(pfd, npfd, timeout); 1590 saved_errno = errno; 1591 if (parent_alive_interval != 0) 1592 check_parent_exists(); 1593 (void) reaper(); /* remove expired keys */ 1594 if (result == -1) { 1595 if (saved_errno == EINTR) 1596 continue; 1597 fatal("poll: %s", strerror(saved_errno)); 1598 } else if (result > 0) 1599 after_poll(pfd, npfd, maxfds); 1600 } 1601 /* NOTREACHED */ 1602 } 1603