1 /* $OpenBSD: ssh-agent.c,v 1.278 2021/04/03 06:18:41 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 __RCSID("$FreeBSD$"); 39 40 #include <sys/types.h> 41 #include <sys/param.h> 42 #include <sys/resource.h> 43 #include <sys/stat.h> 44 #include <sys/socket.h> 45 #include <sys/wait.h> 46 #ifdef HAVE_SYS_TIME_H 47 # include <sys/time.h> 48 #endif 49 #ifdef HAVE_SYS_UN_H 50 # include <sys/un.h> 51 #endif 52 #include "openbsd-compat/sys-queue.h" 53 54 #ifdef WITH_OPENSSL 55 #include <openssl/evp.h> 56 #include "openbsd-compat/openssl-compat.h" 57 #endif 58 59 #include <errno.h> 60 #include <fcntl.h> 61 #include <limits.h> 62 #ifdef HAVE_PATHS_H 63 # include <paths.h> 64 #endif 65 #ifdef HAVE_POLL_H 66 # include <poll.h> 67 #endif 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <time.h> 73 #include <string.h> 74 #include <unistd.h> 75 #ifdef HAVE_UTIL_H 76 # include <util.h> 77 #endif 78 79 #include "xmalloc.h" 80 #include "ssh.h" 81 #include "ssh2.h" 82 #include "sshbuf.h" 83 #include "sshkey.h" 84 #include "authfd.h" 85 #include "compat.h" 86 #include "log.h" 87 #include "misc.h" 88 #include "digest.h" 89 #include "ssherr.h" 90 #include "match.h" 91 #include "msg.h" 92 #include "ssherr.h" 93 #include "pathnames.h" 94 #include "ssh-pkcs11.h" 95 #include "sk-api.h" 96 97 #ifndef DEFAULT_ALLOWED_PROVIDERS 98 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 99 #endif 100 101 /* Maximum accepted message length */ 102 #define AGENT_MAX_LEN (256*1024) 103 /* Maximum bytes to read from client socket */ 104 #define AGENT_RBUF_LEN (4096) 105 106 typedef enum { 107 AUTH_UNUSED = 0, 108 AUTH_SOCKET = 1, 109 AUTH_CONNECTION = 2, 110 } sock_type; 111 112 typedef struct socket_entry { 113 int fd; 114 sock_type type; 115 struct sshbuf *input; 116 struct sshbuf *output; 117 struct sshbuf *request; 118 } SocketEntry; 119 120 u_int sockets_alloc = 0; 121 SocketEntry *sockets = NULL; 122 123 typedef struct identity { 124 TAILQ_ENTRY(identity) next; 125 struct sshkey *key; 126 char *comment; 127 char *provider; 128 time_t death; 129 u_int confirm; 130 char *sk_provider; 131 } Identity; 132 133 struct idtable { 134 int nentries; 135 TAILQ_HEAD(idqueue, identity) idlist; 136 }; 137 138 /* private key table */ 139 struct idtable *idtab; 140 141 int max_fd = 0; 142 143 /* pid of shell == parent of agent */ 144 pid_t parent_pid = -1; 145 time_t parent_alive_interval = 0; 146 147 /* pid of process for which cleanup_socket is applicable */ 148 pid_t cleanup_pid = 0; 149 150 /* pathname and directory for AUTH_SOCKET */ 151 char socket_name[PATH_MAX]; 152 char socket_dir[PATH_MAX]; 153 154 /* Pattern-list of allowed PKCS#11/Security key paths */ 155 static char *allowed_providers; 156 157 /* locking */ 158 #define LOCK_SIZE 32 159 #define LOCK_SALT_SIZE 16 160 #define LOCK_ROUNDS 1 161 int locked = 0; 162 u_char lock_pwhash[LOCK_SIZE]; 163 u_char lock_salt[LOCK_SALT_SIZE]; 164 165 extern char *__progname; 166 167 /* Default lifetime in seconds (0 == forever) */ 168 static int lifetime = 0; 169 170 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 171 172 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 173 static int restrict_websafe = 1; 174 175 /* 176 * Client connection count; incremented in new_socket() and decremented in 177 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 178 * normally initialized to 1, it will never reach 0. However, if the -x 179 * option is specified, it is initialized to 0 in main(); in that case, 180 * ssh-agent will exit as soon as it has had at least one client but no 181 * longer has any. 182 */ 183 static int xcount = 1; 184 185 static void 186 close_socket(SocketEntry *e) 187 { 188 int last = 0; 189 190 if (e->type == AUTH_CONNECTION) { 191 debug("xcount %d -> %d", xcount, xcount - 1); 192 if (--xcount == 0) 193 last = 1; 194 } 195 close(e->fd); 196 sshbuf_free(e->input); 197 sshbuf_free(e->output); 198 sshbuf_free(e->request); 199 memset(e, '\0', sizeof(*e)); 200 e->fd = -1; 201 e->type = AUTH_UNUSED; 202 if (last) 203 cleanup_exit(0); 204 } 205 206 static void 207 idtab_init(void) 208 { 209 idtab = xcalloc(1, sizeof(*idtab)); 210 TAILQ_INIT(&idtab->idlist); 211 idtab->nentries = 0; 212 } 213 214 static void 215 free_identity(Identity *id) 216 { 217 sshkey_free(id->key); 218 free(id->provider); 219 free(id->comment); 220 free(id->sk_provider); 221 free(id); 222 } 223 224 /* return matching private key for given public key */ 225 static Identity * 226 lookup_identity(struct sshkey *key) 227 { 228 Identity *id; 229 230 TAILQ_FOREACH(id, &idtab->idlist, next) { 231 if (sshkey_equal(key, id->key)) 232 return (id); 233 } 234 return (NULL); 235 } 236 237 /* Check confirmation of keysign request */ 238 static int 239 confirm_key(Identity *id, const char *extra) 240 { 241 char *p; 242 int ret = -1; 243 244 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 245 if (p != NULL && 246 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 247 id->comment, p, 248 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 249 ret = 0; 250 free(p); 251 252 return (ret); 253 } 254 255 static void 256 send_status(SocketEntry *e, int success) 257 { 258 int r; 259 260 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 261 (r = sshbuf_put_u8(e->output, success ? 262 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 263 fatal_fr(r, "compose"); 264 } 265 266 /* send list of supported public keys to 'client' */ 267 static void 268 process_request_identities(SocketEntry *e) 269 { 270 Identity *id; 271 struct sshbuf *msg; 272 int r; 273 274 debug2_f("entering"); 275 276 if ((msg = sshbuf_new()) == NULL) 277 fatal_f("sshbuf_new failed"); 278 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 279 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 280 fatal_fr(r, "compose"); 281 TAILQ_FOREACH(id, &idtab->idlist, next) { 282 if ((r = sshkey_puts_opts(id->key, msg, 283 SSHKEY_SERIALIZE_INFO)) != 0 || 284 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 285 error_fr(r, "compose key/comment"); 286 continue; 287 } 288 } 289 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 290 fatal_fr(r, "enqueue"); 291 sshbuf_free(msg); 292 } 293 294 295 static char * 296 agent_decode_alg(struct sshkey *key, u_int flags) 297 { 298 if (key->type == KEY_RSA) { 299 if (flags & SSH_AGENT_RSA_SHA2_256) 300 return "rsa-sha2-256"; 301 else if (flags & SSH_AGENT_RSA_SHA2_512) 302 return "rsa-sha2-512"; 303 } else if (key->type == KEY_RSA_CERT) { 304 if (flags & SSH_AGENT_RSA_SHA2_256) 305 return "rsa-sha2-256-cert-v01@openssh.com"; 306 else if (flags & SSH_AGENT_RSA_SHA2_512) 307 return "rsa-sha2-512-cert-v01@openssh.com"; 308 } 309 return NULL; 310 } 311 312 /* 313 * Attempt to parse the contents of a buffer as a SSH publickey userauth 314 * request, checking its contents for consistency and matching the embedded 315 * key against the one that is being used for signing. 316 * Note: does not modify msg buffer. 317 * Optionally extract the username and session ID from the request. 318 */ 319 static int 320 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 321 char **userp, struct sshbuf **sess_idp) 322 { 323 struct sshbuf *b = NULL, *sess_id = NULL; 324 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 325 int r; 326 u_char t, sig_follows; 327 struct sshkey *mkey = NULL; 328 329 if (userp != NULL) 330 *userp = NULL; 331 if (sess_idp != NULL) 332 *sess_idp = NULL; 333 if ((b = sshbuf_fromb(msg)) == NULL) 334 fatal_f("sshbuf_fromb"); 335 336 /* SSH userauth request */ 337 if ((r = sshbuf_froms(b, &sess_id)) != 0) 338 goto out; 339 if (sshbuf_len(sess_id) == 0) { 340 r = SSH_ERR_INVALID_FORMAT; 341 goto out; 342 } 343 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 344 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 345 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 346 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 347 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 348 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 349 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 350 goto out; 351 if (t != SSH2_MSG_USERAUTH_REQUEST || 352 sig_follows != 1 || 353 strcmp(service, "ssh-connection") != 0 || 354 !sshkey_equal(expected_key, mkey) || 355 sshkey_type_from_name(pkalg) != expected_key->type) { 356 r = SSH_ERR_INVALID_FORMAT; 357 goto out; 358 } 359 if (strcmp(method, "publickey") != 0) { 360 r = SSH_ERR_INVALID_FORMAT; 361 goto out; 362 } 363 if (sshbuf_len(b) != 0) { 364 r = SSH_ERR_INVALID_FORMAT; 365 goto out; 366 } 367 /* success */ 368 r = 0; 369 debug3_f("well formed userauth"); 370 if (userp != NULL) { 371 *userp = user; 372 user = NULL; 373 } 374 if (sess_idp != NULL) { 375 *sess_idp = sess_id; 376 sess_id = NULL; 377 } 378 out: 379 sshbuf_free(b); 380 sshbuf_free(sess_id); 381 free(user); 382 free(service); 383 free(method); 384 free(pkalg); 385 sshkey_free(mkey); 386 return r; 387 } 388 389 /* 390 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 391 * Note: does not modify buffer. 392 */ 393 static int 394 parse_sshsig_request(struct sshbuf *msg) 395 { 396 int r; 397 struct sshbuf *b; 398 399 if ((b = sshbuf_fromb(msg)) == NULL) 400 fatal_f("sshbuf_fromb"); 401 402 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 403 (r = sshbuf_consume(b, 6)) != 0 || 404 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 405 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 406 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 407 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 408 goto out; 409 if (sshbuf_len(b) != 0) { 410 r = SSH_ERR_INVALID_FORMAT; 411 goto out; 412 } 413 /* success */ 414 r = 0; 415 out: 416 sshbuf_free(b); 417 return r; 418 } 419 420 /* 421 * This function inspects a message to be signed by a FIDO key that has a 422 * web-like application string (i.e. one that does not begin with "ssh:". 423 * It checks that the message is one of those expected for SSH operations 424 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 425 * for the web. 426 */ 427 static int 428 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 429 { 430 if (parse_userauth_request(data, key, NULL, NULL) == 0) { 431 debug_f("signed data matches public key userauth request"); 432 return 1; 433 } 434 if (parse_sshsig_request(data) == 0) { 435 debug_f("signed data matches SSHSIG signature request"); 436 return 1; 437 } 438 439 /* XXX check CA signature operation */ 440 441 error("web-origin key attempting to sign non-SSH message"); 442 return 0; 443 } 444 445 /* ssh2 only */ 446 static void 447 process_sign_request2(SocketEntry *e) 448 { 449 u_char *signature = NULL; 450 size_t slen = 0; 451 u_int compat = 0, flags; 452 int r, ok = -1; 453 char *fp = NULL; 454 struct sshbuf *msg = NULL, *data = NULL; 455 struct sshkey *key = NULL; 456 struct identity *id; 457 struct notifier_ctx *notifier = NULL; 458 459 debug_f("entering"); 460 461 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 462 fatal_f("sshbuf_new failed"); 463 if ((r = sshkey_froms(e->request, &key)) != 0 || 464 (r = sshbuf_get_stringb(e->request, data)) != 0 || 465 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 466 error_fr(r, "parse"); 467 goto send; 468 } 469 470 if ((id = lookup_identity(key)) == NULL) { 471 verbose_f("%s key not found", sshkey_type(key)); 472 goto send; 473 } 474 if (id->confirm && confirm_key(id, NULL) != 0) { 475 verbose_f("user refused key"); 476 goto send; 477 } 478 if (sshkey_is_sk(id->key)) { 479 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 480 !check_websafe_message_contents(key, data)) { 481 /* error already logged */ 482 goto send; 483 } 484 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 485 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 486 SSH_FP_DEFAULT)) == NULL) 487 fatal_f("fingerprint failed"); 488 notifier = notify_start(0, 489 "Confirm user presence for key %s %s", 490 sshkey_type(id->key), fp); 491 } 492 } 493 /* XXX support PIN required FIDO keys */ 494 if ((r = sshkey_sign(id->key, &signature, &slen, 495 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 496 id->sk_provider, NULL, compat)) != 0) { 497 error_fr(r, "sshkey_sign"); 498 goto send; 499 } 500 /* Success */ 501 ok = 0; 502 send: 503 notify_complete(notifier, "User presence confirmed"); 504 505 if (ok == 0) { 506 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 507 (r = sshbuf_put_string(msg, signature, slen)) != 0) 508 fatal_fr(r, "compose"); 509 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 510 fatal_fr(r, "compose failure"); 511 512 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 513 fatal_fr(r, "enqueue"); 514 515 sshbuf_free(data); 516 sshbuf_free(msg); 517 sshkey_free(key); 518 free(fp); 519 free(signature); 520 } 521 522 /* shared */ 523 static void 524 process_remove_identity(SocketEntry *e) 525 { 526 int r, success = 0; 527 struct sshkey *key = NULL; 528 Identity *id; 529 530 debug2_f("entering"); 531 if ((r = sshkey_froms(e->request, &key)) != 0) { 532 error_fr(r, "parse key"); 533 goto done; 534 } 535 if ((id = lookup_identity(key)) == NULL) { 536 debug_f("key not found"); 537 goto done; 538 } 539 /* We have this key, free it. */ 540 if (idtab->nentries < 1) 541 fatal_f("internal error: nentries %d", idtab->nentries); 542 TAILQ_REMOVE(&idtab->idlist, id, next); 543 free_identity(id); 544 idtab->nentries--; 545 success = 1; 546 done: 547 sshkey_free(key); 548 send_status(e, success); 549 } 550 551 static void 552 process_remove_all_identities(SocketEntry *e) 553 { 554 Identity *id; 555 556 debug2_f("entering"); 557 /* Loop over all identities and clear the keys. */ 558 for (id = TAILQ_FIRST(&idtab->idlist); id; 559 id = TAILQ_FIRST(&idtab->idlist)) { 560 TAILQ_REMOVE(&idtab->idlist, id, next); 561 free_identity(id); 562 } 563 564 /* Mark that there are no identities. */ 565 idtab->nentries = 0; 566 567 /* Send success. */ 568 send_status(e, 1); 569 } 570 571 /* removes expired keys and returns number of seconds until the next expiry */ 572 static time_t 573 reaper(void) 574 { 575 time_t deadline = 0, now = monotime(); 576 Identity *id, *nxt; 577 578 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 579 nxt = TAILQ_NEXT(id, next); 580 if (id->death == 0) 581 continue; 582 if (now >= id->death) { 583 debug("expiring key '%s'", id->comment); 584 TAILQ_REMOVE(&idtab->idlist, id, next); 585 free_identity(id); 586 idtab->nentries--; 587 } else 588 deadline = (deadline == 0) ? id->death : 589 MINIMUM(deadline, id->death); 590 } 591 if (deadline == 0 || deadline <= now) 592 return 0; 593 else 594 return (deadline - now); 595 } 596 597 static int 598 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp) 599 { 600 char *ext_name = NULL; 601 int r; 602 603 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 604 error_fr(r, "parse constraint extension"); 605 goto out; 606 } 607 debug_f("constraint ext %s", ext_name); 608 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 609 if (sk_providerp == NULL) { 610 error_f("%s not valid here", ext_name); 611 r = SSH_ERR_INVALID_FORMAT; 612 goto out; 613 } 614 if (*sk_providerp != NULL) { 615 error_f("%s already set", ext_name); 616 r = SSH_ERR_INVALID_FORMAT; 617 goto out; 618 } 619 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 620 error_fr(r, "parse %s", ext_name); 621 goto out; 622 } 623 } else { 624 error_f("unsupported constraint \"%s\"", ext_name); 625 r = SSH_ERR_FEATURE_UNSUPPORTED; 626 goto out; 627 } 628 /* success */ 629 r = 0; 630 out: 631 free(ext_name); 632 return r; 633 } 634 635 static int 636 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 637 u_int *secondsp, int *confirmp, char **sk_providerp) 638 { 639 u_char ctype; 640 int r; 641 u_int seconds, maxsign = 0; 642 643 while (sshbuf_len(m)) { 644 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 645 error_fr(r, "parse constraint type"); 646 goto out; 647 } 648 switch (ctype) { 649 case SSH_AGENT_CONSTRAIN_LIFETIME: 650 if (*deathp != 0) { 651 error_f("lifetime already set"); 652 r = SSH_ERR_INVALID_FORMAT; 653 goto out; 654 } 655 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 656 error_fr(r, "parse lifetime constraint"); 657 goto out; 658 } 659 *deathp = monotime() + seconds; 660 *secondsp = seconds; 661 break; 662 case SSH_AGENT_CONSTRAIN_CONFIRM: 663 if (*confirmp != 0) { 664 error_f("confirm already set"); 665 r = SSH_ERR_INVALID_FORMAT; 666 goto out; 667 } 668 *confirmp = 1; 669 break; 670 case SSH_AGENT_CONSTRAIN_MAXSIGN: 671 if (k == NULL) { 672 error_f("maxsign not valid here"); 673 r = SSH_ERR_INVALID_FORMAT; 674 goto out; 675 } 676 if (maxsign != 0) { 677 error_f("maxsign already set"); 678 r = SSH_ERR_INVALID_FORMAT; 679 goto out; 680 } 681 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 682 error_fr(r, "parse maxsign constraint"); 683 goto out; 684 } 685 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 686 error_fr(r, "enable maxsign"); 687 goto out; 688 } 689 break; 690 case SSH_AGENT_CONSTRAIN_EXTENSION: 691 if ((r = parse_key_constraint_extension(m, 692 sk_providerp)) != 0) 693 goto out; /* error already logged */ 694 break; 695 default: 696 error_f("Unknown constraint %d", ctype); 697 r = SSH_ERR_FEATURE_UNSUPPORTED; 698 goto out; 699 } 700 } 701 /* success */ 702 r = 0; 703 out: 704 return r; 705 } 706 707 static void 708 process_add_identity(SocketEntry *e) 709 { 710 Identity *id; 711 int success = 0, confirm = 0; 712 char *fp, *comment = NULL, *sk_provider = NULL; 713 char canonical_provider[PATH_MAX]; 714 time_t death = 0; 715 u_int seconds = 0; 716 struct sshkey *k = NULL; 717 int r = SSH_ERR_INTERNAL_ERROR; 718 719 debug2_f("entering"); 720 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 721 k == NULL || 722 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 723 error_fr(r, "parse"); 724 goto out; 725 } 726 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 727 &sk_provider) != 0) { 728 error_f("failed to parse constraints"); 729 sshbuf_reset(e->request); 730 goto out; 731 } 732 733 if (sk_provider != NULL) { 734 if (!sshkey_is_sk(k)) { 735 error("Cannot add provider: %s is not an " 736 "authenticator-hosted key", sshkey_type(k)); 737 goto out; 738 } 739 if (strcasecmp(sk_provider, "internal") == 0) { 740 debug_f("internal provider"); 741 } else { 742 if (realpath(sk_provider, canonical_provider) == NULL) { 743 verbose("failed provider \"%.100s\": " 744 "realpath: %s", sk_provider, 745 strerror(errno)); 746 goto out; 747 } 748 free(sk_provider); 749 sk_provider = xstrdup(canonical_provider); 750 if (match_pattern_list(sk_provider, 751 allowed_providers, 0) != 1) { 752 error("Refusing add key: " 753 "provider %s not allowed", sk_provider); 754 goto out; 755 } 756 } 757 } 758 if ((r = sshkey_shield_private(k)) != 0) { 759 error_fr(r, "shield private"); 760 goto out; 761 } 762 if (lifetime && !death) 763 death = monotime() + lifetime; 764 if ((id = lookup_identity(k)) == NULL) { 765 id = xcalloc(1, sizeof(Identity)); 766 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 767 /* Increment the number of identities. */ 768 idtab->nentries++; 769 } else { 770 /* key state might have been updated */ 771 sshkey_free(id->key); 772 free(id->comment); 773 free(id->sk_provider); 774 } 775 /* success */ 776 id->key = k; 777 id->comment = comment; 778 id->death = death; 779 id->confirm = confirm; 780 id->sk_provider = sk_provider; 781 782 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 783 SSH_FP_DEFAULT)) == NULL) 784 fatal_f("sshkey_fingerprint failed"); 785 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 786 "(provider: %s)", sshkey_ssh_name(k), fp, comment, seconds, 787 confirm, sk_provider == NULL ? "none" : sk_provider); 788 free(fp); 789 /* transferred */ 790 k = NULL; 791 comment = NULL; 792 sk_provider = NULL; 793 success = 1; 794 out: 795 free(sk_provider); 796 free(comment); 797 sshkey_free(k); 798 send_status(e, success); 799 } 800 801 /* XXX todo: encrypt sensitive data with passphrase */ 802 static void 803 process_lock_agent(SocketEntry *e, int lock) 804 { 805 int r, success = 0, delay; 806 char *passwd; 807 u_char passwdhash[LOCK_SIZE]; 808 static u_int fail_count = 0; 809 size_t pwlen; 810 811 debug2_f("entering"); 812 /* 813 * This is deliberately fatal: the user has requested that we lock, 814 * but we can't parse their request properly. The only safe thing to 815 * do is abort. 816 */ 817 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 818 fatal_fr(r, "parse"); 819 if (pwlen == 0) { 820 debug("empty password not supported"); 821 } else if (locked && !lock) { 822 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 823 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 824 fatal("bcrypt_pbkdf"); 825 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 826 debug("agent unlocked"); 827 locked = 0; 828 fail_count = 0; 829 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 830 success = 1; 831 } else { 832 /* delay in 0.1s increments up to 10s */ 833 if (fail_count < 100) 834 fail_count++; 835 delay = 100000 * fail_count; 836 debug("unlock failed, delaying %0.1lf seconds", 837 (double)delay/1000000); 838 usleep(delay); 839 } 840 explicit_bzero(passwdhash, sizeof(passwdhash)); 841 } else if (!locked && lock) { 842 debug("agent locked"); 843 locked = 1; 844 arc4random_buf(lock_salt, sizeof(lock_salt)); 845 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 846 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 847 fatal("bcrypt_pbkdf"); 848 success = 1; 849 } 850 freezero(passwd, pwlen); 851 send_status(e, success); 852 } 853 854 static void 855 no_identities(SocketEntry *e) 856 { 857 struct sshbuf *msg; 858 int r; 859 860 if ((msg = sshbuf_new()) == NULL) 861 fatal_f("sshbuf_new failed"); 862 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 863 (r = sshbuf_put_u32(msg, 0)) != 0 || 864 (r = sshbuf_put_stringb(e->output, msg)) != 0) 865 fatal_fr(r, "compose"); 866 sshbuf_free(msg); 867 } 868 869 #ifdef ENABLE_PKCS11 870 static void 871 process_add_smartcard_key(SocketEntry *e) 872 { 873 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 874 char **comments = NULL; 875 int r, i, count = 0, success = 0, confirm = 0; 876 u_int seconds = 0; 877 time_t death = 0; 878 struct sshkey **keys = NULL, *k; 879 Identity *id; 880 881 debug2_f("entering"); 882 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 883 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 884 error_fr(r, "parse"); 885 goto send; 886 } 887 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 888 NULL) != 0) { 889 error_f("failed to parse constraints"); 890 goto send; 891 } 892 if (realpath(provider, canonical_provider) == NULL) { 893 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 894 provider, strerror(errno)); 895 goto send; 896 } 897 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 898 verbose("refusing PKCS#11 add of \"%.100s\": " 899 "provider not allowed", canonical_provider); 900 goto send; 901 } 902 debug_f("add %.100s", canonical_provider); 903 if (lifetime && !death) 904 death = monotime() + lifetime; 905 906 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 907 for (i = 0; i < count; i++) { 908 k = keys[i]; 909 if (lookup_identity(k) == NULL) { 910 id = xcalloc(1, sizeof(Identity)); 911 id->key = k; 912 keys[i] = NULL; /* transferred */ 913 id->provider = xstrdup(canonical_provider); 914 if (*comments[i] != '\0') { 915 id->comment = comments[i]; 916 comments[i] = NULL; /* transferred */ 917 } else { 918 id->comment = xstrdup(canonical_provider); 919 } 920 id->death = death; 921 id->confirm = confirm; 922 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 923 idtab->nentries++; 924 success = 1; 925 } 926 /* XXX update constraints for existing keys */ 927 sshkey_free(keys[i]); 928 free(comments[i]); 929 } 930 send: 931 free(pin); 932 free(provider); 933 free(keys); 934 free(comments); 935 send_status(e, success); 936 } 937 938 static void 939 process_remove_smartcard_key(SocketEntry *e) 940 { 941 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 942 int r, success = 0; 943 Identity *id, *nxt; 944 945 debug2_f("entering"); 946 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 947 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 948 error_fr(r, "parse"); 949 goto send; 950 } 951 free(pin); 952 953 if (realpath(provider, canonical_provider) == NULL) { 954 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 955 provider, strerror(errno)); 956 goto send; 957 } 958 959 debug_f("remove %.100s", canonical_provider); 960 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 961 nxt = TAILQ_NEXT(id, next); 962 /* Skip file--based keys */ 963 if (id->provider == NULL) 964 continue; 965 if (!strcmp(canonical_provider, id->provider)) { 966 TAILQ_REMOVE(&idtab->idlist, id, next); 967 free_identity(id); 968 idtab->nentries--; 969 } 970 } 971 if (pkcs11_del_provider(canonical_provider) == 0) 972 success = 1; 973 else 974 error_f("pkcs11_del_provider failed"); 975 send: 976 free(provider); 977 send_status(e, success); 978 } 979 #endif /* ENABLE_PKCS11 */ 980 981 /* 982 * dispatch incoming message. 983 * returns 1 on success, 0 for incomplete messages or -1 on error. 984 */ 985 static int 986 process_message(u_int socknum) 987 { 988 u_int msg_len; 989 u_char type; 990 const u_char *cp; 991 int r; 992 SocketEntry *e; 993 994 if (socknum >= sockets_alloc) 995 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 996 e = &sockets[socknum]; 997 998 if (sshbuf_len(e->input) < 5) 999 return 0; /* Incomplete message header. */ 1000 cp = sshbuf_ptr(e->input); 1001 msg_len = PEEK_U32(cp); 1002 if (msg_len > AGENT_MAX_LEN) { 1003 debug_f("socket %u (fd=%d) message too long %u > %u", 1004 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1005 return -1; 1006 } 1007 if (sshbuf_len(e->input) < msg_len + 4) 1008 return 0; /* Incomplete message body. */ 1009 1010 /* move the current input to e->request */ 1011 sshbuf_reset(e->request); 1012 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1013 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1014 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1015 r == SSH_ERR_STRING_TOO_LARGE) { 1016 error_fr(r, "parse"); 1017 return -1; 1018 } 1019 fatal_fr(r, "parse"); 1020 } 1021 1022 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1023 1024 /* check whether agent is locked */ 1025 if (locked && type != SSH_AGENTC_UNLOCK) { 1026 sshbuf_reset(e->request); 1027 switch (type) { 1028 case SSH2_AGENTC_REQUEST_IDENTITIES: 1029 /* send empty lists */ 1030 no_identities(e); 1031 break; 1032 default: 1033 /* send a fail message for all other request types */ 1034 send_status(e, 0); 1035 } 1036 return 1; 1037 } 1038 1039 switch (type) { 1040 case SSH_AGENTC_LOCK: 1041 case SSH_AGENTC_UNLOCK: 1042 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1043 break; 1044 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1045 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1046 break; 1047 /* ssh2 */ 1048 case SSH2_AGENTC_SIGN_REQUEST: 1049 process_sign_request2(e); 1050 break; 1051 case SSH2_AGENTC_REQUEST_IDENTITIES: 1052 process_request_identities(e); 1053 break; 1054 case SSH2_AGENTC_ADD_IDENTITY: 1055 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1056 process_add_identity(e); 1057 break; 1058 case SSH2_AGENTC_REMOVE_IDENTITY: 1059 process_remove_identity(e); 1060 break; 1061 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1062 process_remove_all_identities(e); 1063 break; 1064 #ifdef ENABLE_PKCS11 1065 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1066 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1067 process_add_smartcard_key(e); 1068 break; 1069 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1070 process_remove_smartcard_key(e); 1071 break; 1072 #endif /* ENABLE_PKCS11 */ 1073 default: 1074 /* Unknown message. Respond with failure. */ 1075 error("Unknown message %d", type); 1076 sshbuf_reset(e->request); 1077 send_status(e, 0); 1078 break; 1079 } 1080 return 1; 1081 } 1082 1083 static void 1084 new_socket(sock_type type, int fd) 1085 { 1086 u_int i, old_alloc, new_alloc; 1087 1088 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1089 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1090 if (type == AUTH_CONNECTION) { 1091 debug("xcount %d -> %d", xcount, xcount + 1); 1092 ++xcount; 1093 } 1094 set_nonblock(fd); 1095 1096 if (fd > max_fd) 1097 max_fd = fd; 1098 1099 for (i = 0; i < sockets_alloc; i++) 1100 if (sockets[i].type == AUTH_UNUSED) { 1101 sockets[i].fd = fd; 1102 if ((sockets[i].input = sshbuf_new()) == NULL || 1103 (sockets[i].output = sshbuf_new()) == NULL || 1104 (sockets[i].request = sshbuf_new()) == NULL) 1105 fatal_f("sshbuf_new failed"); 1106 sockets[i].type = type; 1107 return; 1108 } 1109 old_alloc = sockets_alloc; 1110 new_alloc = sockets_alloc + 10; 1111 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1112 sizeof(sockets[0])); 1113 for (i = old_alloc; i < new_alloc; i++) 1114 sockets[i].type = AUTH_UNUSED; 1115 sockets_alloc = new_alloc; 1116 sockets[old_alloc].fd = fd; 1117 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1118 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1119 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1120 fatal_f("sshbuf_new failed"); 1121 sockets[old_alloc].type = type; 1122 } 1123 1124 static int 1125 handle_socket_read(u_int socknum) 1126 { 1127 struct sockaddr_un sunaddr; 1128 socklen_t slen; 1129 uid_t euid; 1130 gid_t egid; 1131 int fd; 1132 1133 slen = sizeof(sunaddr); 1134 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1135 if (fd == -1) { 1136 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1137 return -1; 1138 } 1139 if (getpeereid(fd, &euid, &egid) == -1) { 1140 error("getpeereid %d failed: %s", fd, strerror(errno)); 1141 close(fd); 1142 return -1; 1143 } 1144 if ((euid != 0) && (getuid() != euid)) { 1145 error("uid mismatch: peer euid %u != uid %u", 1146 (u_int) euid, (u_int) getuid()); 1147 close(fd); 1148 return -1; 1149 } 1150 new_socket(AUTH_CONNECTION, fd); 1151 return 0; 1152 } 1153 1154 static int 1155 handle_conn_read(u_int socknum) 1156 { 1157 char buf[AGENT_RBUF_LEN]; 1158 ssize_t len; 1159 int r; 1160 1161 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1162 if (len == -1) { 1163 if (errno == EAGAIN || errno == EINTR) 1164 return 0; 1165 error_f("read error on socket %u (fd %d): %s", 1166 socknum, sockets[socknum].fd, strerror(errno)); 1167 } 1168 return -1; 1169 } 1170 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1171 fatal_fr(r, "compose"); 1172 explicit_bzero(buf, sizeof(buf)); 1173 for (;;) { 1174 if ((r = process_message(socknum)) == -1) 1175 return -1; 1176 else if (r == 0) 1177 break; 1178 } 1179 return 0; 1180 } 1181 1182 static int 1183 handle_conn_write(u_int socknum) 1184 { 1185 ssize_t len; 1186 int r; 1187 1188 if (sshbuf_len(sockets[socknum].output) == 0) 1189 return 0; /* shouldn't happen */ 1190 if ((len = write(sockets[socknum].fd, 1191 sshbuf_ptr(sockets[socknum].output), 1192 sshbuf_len(sockets[socknum].output))) <= 0) { 1193 if (len == -1) { 1194 if (errno == EAGAIN || errno == EINTR) 1195 return 0; 1196 error_f("read error on socket %u (fd %d): %s", 1197 socknum, sockets[socknum].fd, strerror(errno)); 1198 } 1199 return -1; 1200 } 1201 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1202 fatal_fr(r, "consume"); 1203 return 0; 1204 } 1205 1206 static void 1207 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1208 { 1209 size_t i; 1210 u_int socknum, activefds = npfd; 1211 1212 for (i = 0; i < npfd; i++) { 1213 if (pfd[i].revents == 0) 1214 continue; 1215 /* Find sockets entry */ 1216 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1217 if (sockets[socknum].type != AUTH_SOCKET && 1218 sockets[socknum].type != AUTH_CONNECTION) 1219 continue; 1220 if (pfd[i].fd == sockets[socknum].fd) 1221 break; 1222 } 1223 if (socknum >= sockets_alloc) { 1224 error_f("no socket for fd %d", pfd[i].fd); 1225 continue; 1226 } 1227 /* Process events */ 1228 switch (sockets[socknum].type) { 1229 case AUTH_SOCKET: 1230 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1231 break; 1232 if (npfd > maxfds) { 1233 debug3("out of fds (active %u >= limit %u); " 1234 "skipping accept", activefds, maxfds); 1235 break; 1236 } 1237 if (handle_socket_read(socknum) == 0) 1238 activefds++; 1239 break; 1240 case AUTH_CONNECTION: 1241 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1242 handle_conn_read(socknum) != 0) { 1243 goto close_sock; 1244 } 1245 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1246 handle_conn_write(socknum) != 0) { 1247 close_sock: 1248 if (activefds == 0) 1249 fatal("activefds == 0 at close_sock"); 1250 close_socket(&sockets[socknum]); 1251 activefds--; 1252 break; 1253 } 1254 break; 1255 default: 1256 break; 1257 } 1258 } 1259 } 1260 1261 static int 1262 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1263 { 1264 struct pollfd *pfd = *pfdp; 1265 size_t i, j, npfd = 0; 1266 time_t deadline; 1267 int r; 1268 1269 /* Count active sockets */ 1270 for (i = 0; i < sockets_alloc; i++) { 1271 switch (sockets[i].type) { 1272 case AUTH_SOCKET: 1273 case AUTH_CONNECTION: 1274 npfd++; 1275 break; 1276 case AUTH_UNUSED: 1277 break; 1278 default: 1279 fatal("Unknown socket type %d", sockets[i].type); 1280 break; 1281 } 1282 } 1283 if (npfd != *npfdp && 1284 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1285 fatal_f("recallocarray failed"); 1286 *pfdp = pfd; 1287 *npfdp = npfd; 1288 1289 for (i = j = 0; i < sockets_alloc; i++) { 1290 switch (sockets[i].type) { 1291 case AUTH_SOCKET: 1292 if (npfd > maxfds) { 1293 debug3("out of fds (active %zu >= limit %u); " 1294 "skipping arming listener", npfd, maxfds); 1295 break; 1296 } 1297 pfd[j].fd = sockets[i].fd; 1298 pfd[j].revents = 0; 1299 pfd[j].events = POLLIN; 1300 j++; 1301 break; 1302 case AUTH_CONNECTION: 1303 pfd[j].fd = sockets[i].fd; 1304 pfd[j].revents = 0; 1305 /* 1306 * Only prepare to read if we can handle a full-size 1307 * input read buffer and enqueue a max size reply.. 1308 */ 1309 if ((r = sshbuf_check_reserve(sockets[i].input, 1310 AGENT_RBUF_LEN)) == 0 && 1311 (r = sshbuf_check_reserve(sockets[i].output, 1312 AGENT_MAX_LEN)) == 0) 1313 pfd[j].events = POLLIN; 1314 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1315 fatal_fr(r, "reserve"); 1316 if (sshbuf_len(sockets[i].output) > 0) 1317 pfd[j].events |= POLLOUT; 1318 j++; 1319 break; 1320 default: 1321 break; 1322 } 1323 } 1324 deadline = reaper(); 1325 if (parent_alive_interval != 0) 1326 deadline = (deadline == 0) ? parent_alive_interval : 1327 MINIMUM(deadline, parent_alive_interval); 1328 if (deadline == 0) { 1329 *timeoutp = -1; /* INFTIM */ 1330 } else { 1331 if (deadline > INT_MAX / 1000) 1332 *timeoutp = INT_MAX / 1000; 1333 else 1334 *timeoutp = deadline * 1000; 1335 } 1336 return (1); 1337 } 1338 1339 static void 1340 cleanup_socket(void) 1341 { 1342 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1343 return; 1344 debug_f("cleanup"); 1345 if (socket_name[0]) 1346 unlink(socket_name); 1347 if (socket_dir[0]) 1348 rmdir(socket_dir); 1349 } 1350 1351 void 1352 cleanup_exit(int i) 1353 { 1354 cleanup_socket(); 1355 _exit(i); 1356 } 1357 1358 /*ARGSUSED*/ 1359 static void 1360 cleanup_handler(int sig) 1361 { 1362 cleanup_socket(); 1363 #ifdef ENABLE_PKCS11 1364 pkcs11_terminate(); 1365 #endif 1366 _exit(2); 1367 } 1368 1369 static void 1370 check_parent_exists(void) 1371 { 1372 /* 1373 * If our parent has exited then getppid() will return (pid_t)1, 1374 * so testing for that should be safe. 1375 */ 1376 if (parent_pid != -1 && getppid() != parent_pid) { 1377 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1378 cleanup_socket(); 1379 _exit(2); 1380 } 1381 } 1382 1383 static void 1384 usage(void) 1385 { 1386 fprintf(stderr, 1387 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 1388 " [-P allowed_providers] [-t life]\n" 1389 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1390 " [-t life] command [arg ...]\n" 1391 " ssh-agent [-c | -s] -k\n"); 1392 exit(1); 1393 } 1394 1395 int 1396 main(int ac, char **av) 1397 { 1398 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1399 int sock, ch, result, saved_errno; 1400 char *shell, *format, *pidstr, *agentsocket = NULL; 1401 #ifdef HAVE_SETRLIMIT 1402 struct rlimit rlim; 1403 #endif 1404 extern int optind; 1405 extern char *optarg; 1406 pid_t pid; 1407 char pidstrbuf[1 + 3 * sizeof pid]; 1408 size_t len; 1409 mode_t prev_mask; 1410 int timeout = -1; /* INFTIM */ 1411 struct pollfd *pfd = NULL; 1412 size_t npfd = 0; 1413 u_int maxfds; 1414 1415 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1416 sanitise_stdfd(); 1417 1418 /* drop */ 1419 setegid(getgid()); 1420 setgid(getgid()); 1421 setuid(geteuid()); 1422 1423 platform_disable_tracing(0); /* strict=no */ 1424 1425 #ifdef RLIMIT_NOFILE 1426 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1427 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1428 #endif 1429 1430 __progname = ssh_get_progname(av[0]); 1431 seed_rng(); 1432 1433 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 1434 switch (ch) { 1435 case 'E': 1436 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1437 if (fingerprint_hash == -1) 1438 fatal("Invalid hash algorithm \"%s\"", optarg); 1439 break; 1440 case 'c': 1441 if (s_flag) 1442 usage(); 1443 c_flag++; 1444 break; 1445 case 'k': 1446 k_flag++; 1447 break; 1448 case 'O': 1449 if (strcmp(optarg, "no-restrict-websafe") == 0) 1450 restrict_websafe = 0; 1451 else 1452 fatal("Unknown -O option"); 1453 break; 1454 case 'P': 1455 if (allowed_providers != NULL) 1456 fatal("-P option already specified"); 1457 allowed_providers = xstrdup(optarg); 1458 break; 1459 case 's': 1460 if (c_flag) 1461 usage(); 1462 s_flag++; 1463 break; 1464 case 'd': 1465 if (d_flag || D_flag) 1466 usage(); 1467 d_flag++; 1468 break; 1469 case 'D': 1470 if (d_flag || D_flag) 1471 usage(); 1472 D_flag++; 1473 break; 1474 case 'a': 1475 agentsocket = optarg; 1476 break; 1477 case 't': 1478 if ((lifetime = convtime(optarg)) == -1) { 1479 fprintf(stderr, "Invalid lifetime\n"); 1480 usage(); 1481 } 1482 break; 1483 case 'x': 1484 xcount = 0; 1485 break; 1486 default: 1487 usage(); 1488 } 1489 } 1490 ac -= optind; 1491 av += optind; 1492 1493 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1494 usage(); 1495 1496 if (allowed_providers == NULL) 1497 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1498 1499 if (ac == 0 && !c_flag && !s_flag) { 1500 shell = getenv("SHELL"); 1501 if (shell != NULL && (len = strlen(shell)) > 2 && 1502 strncmp(shell + len - 3, "csh", 3) == 0) 1503 c_flag = 1; 1504 } 1505 if (k_flag) { 1506 const char *errstr = NULL; 1507 1508 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1509 if (pidstr == NULL) { 1510 fprintf(stderr, "%s not set, cannot kill agent\n", 1511 SSH_AGENTPID_ENV_NAME); 1512 exit(1); 1513 } 1514 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1515 if (errstr) { 1516 fprintf(stderr, 1517 "%s=\"%s\", which is not a good PID: %s\n", 1518 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1519 exit(1); 1520 } 1521 if (kill(pid, SIGTERM) == -1) { 1522 perror("kill"); 1523 exit(1); 1524 } 1525 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1526 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1527 printf(format, SSH_AGENTPID_ENV_NAME); 1528 printf("echo Agent pid %ld killed;\n", (long)pid); 1529 exit(0); 1530 } 1531 1532 /* 1533 * Minimum file descriptors: 1534 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1535 * a few spare for libc / stack protectors / sanitisers, etc. 1536 */ 1537 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1538 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1539 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1540 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1541 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1542 1543 parent_pid = getpid(); 1544 1545 if (agentsocket == NULL) { 1546 /* Create private directory for agent socket */ 1547 mktemp_proto(socket_dir, sizeof(socket_dir)); 1548 if (mkdtemp(socket_dir) == NULL) { 1549 perror("mkdtemp: private socket dir"); 1550 exit(1); 1551 } 1552 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1553 (long)parent_pid); 1554 } else { 1555 /* Try to use specified agent socket */ 1556 socket_dir[0] = '\0'; 1557 strlcpy(socket_name, agentsocket, sizeof socket_name); 1558 } 1559 1560 /* 1561 * Create socket early so it will exist before command gets run from 1562 * the parent. 1563 */ 1564 prev_mask = umask(0177); 1565 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1566 if (sock < 0) { 1567 /* XXX - unix_listener() calls error() not perror() */ 1568 *socket_name = '\0'; /* Don't unlink any existing file */ 1569 cleanup_exit(1); 1570 } 1571 umask(prev_mask); 1572 1573 /* 1574 * Fork, and have the parent execute the command, if any, or present 1575 * the socket data. The child continues as the authentication agent. 1576 */ 1577 if (D_flag || d_flag) { 1578 log_init(__progname, 1579 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1580 SYSLOG_FACILITY_AUTH, 1); 1581 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1582 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1583 SSH_AUTHSOCKET_ENV_NAME); 1584 printf("echo Agent pid %ld;\n", (long)parent_pid); 1585 fflush(stdout); 1586 goto skip; 1587 } 1588 pid = fork(); 1589 if (pid == -1) { 1590 perror("fork"); 1591 cleanup_exit(1); 1592 } 1593 if (pid != 0) { /* Parent - execute the given command. */ 1594 close(sock); 1595 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1596 if (ac == 0) { 1597 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1598 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1599 SSH_AUTHSOCKET_ENV_NAME); 1600 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1601 SSH_AGENTPID_ENV_NAME); 1602 printf("echo Agent pid %ld;\n", (long)pid); 1603 exit(0); 1604 } 1605 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1606 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1607 perror("setenv"); 1608 exit(1); 1609 } 1610 execvp(av[0], av); 1611 perror(av[0]); 1612 exit(1); 1613 } 1614 /* child */ 1615 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1616 1617 if (setsid() == -1) { 1618 error("setsid: %s", strerror(errno)); 1619 cleanup_exit(1); 1620 } 1621 1622 (void)chdir("/"); 1623 if (stdfd_devnull(1, 1, 1) == -1) 1624 error_f("stdfd_devnull failed"); 1625 1626 #ifdef HAVE_SETRLIMIT 1627 /* deny core dumps, since memory contains unencrypted private keys */ 1628 rlim.rlim_cur = rlim.rlim_max = 0; 1629 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1630 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1631 cleanup_exit(1); 1632 } 1633 #endif 1634 1635 skip: 1636 1637 cleanup_pid = getpid(); 1638 1639 #ifdef ENABLE_PKCS11 1640 pkcs11_init(0); 1641 #endif 1642 new_socket(AUTH_SOCKET, sock); 1643 if (ac > 0) 1644 parent_alive_interval = 10; 1645 idtab_init(); 1646 ssh_signal(SIGPIPE, SIG_IGN); 1647 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1648 ssh_signal(SIGHUP, cleanup_handler); 1649 ssh_signal(SIGTERM, cleanup_handler); 1650 1651 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1652 fatal("%s: pledge: %s", __progname, strerror(errno)); 1653 platform_pledge_agent(); 1654 1655 while (1) { 1656 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1657 result = poll(pfd, npfd, timeout); 1658 saved_errno = errno; 1659 if (parent_alive_interval != 0) 1660 check_parent_exists(); 1661 (void) reaper(); /* remove expired keys */ 1662 if (result == -1) { 1663 if (saved_errno == EINTR) 1664 continue; 1665 fatal("poll: %s", strerror(saved_errno)); 1666 } else if (result > 0) 1667 after_poll(pfd, npfd, maxfds); 1668 } 1669 /* NOTREACHED */ 1670 } 1671