1 /* $OpenBSD: ssh-agent.c,v 1.279 2021/11/18 03:31:44 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, 249 SSHKEY_SERIALIZE_INFO)) != 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_constraint_extension(struct sshbuf *m, char **sk_providerp) 565 { 566 char *ext_name = NULL; 567 int r; 568 569 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 570 error_fr(r, "parse constraint extension"); 571 goto out; 572 } 573 debug_f("constraint ext %s", ext_name); 574 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 575 if (sk_providerp == NULL) { 576 error_f("%s not valid here", ext_name); 577 r = SSH_ERR_INVALID_FORMAT; 578 goto out; 579 } 580 if (*sk_providerp != NULL) { 581 error_f("%s already set", ext_name); 582 r = SSH_ERR_INVALID_FORMAT; 583 goto out; 584 } 585 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 586 error_fr(r, "parse %s", ext_name); 587 goto out; 588 } 589 } else { 590 error_f("unsupported constraint \"%s\"", ext_name); 591 r = SSH_ERR_FEATURE_UNSUPPORTED; 592 goto out; 593 } 594 /* success */ 595 r = 0; 596 out: 597 free(ext_name); 598 return r; 599 } 600 601 static int 602 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 603 u_int *secondsp, int *confirmp, char **sk_providerp) 604 { 605 u_char ctype; 606 int r; 607 u_int seconds, maxsign = 0; 608 609 while (sshbuf_len(m)) { 610 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 611 error_fr(r, "parse constraint type"); 612 goto out; 613 } 614 switch (ctype) { 615 case SSH_AGENT_CONSTRAIN_LIFETIME: 616 if (*deathp != 0) { 617 error_f("lifetime already set"); 618 r = SSH_ERR_INVALID_FORMAT; 619 goto out; 620 } 621 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 622 error_fr(r, "parse lifetime constraint"); 623 goto out; 624 } 625 *deathp = monotime() + seconds; 626 *secondsp = seconds; 627 break; 628 case SSH_AGENT_CONSTRAIN_CONFIRM: 629 if (*confirmp != 0) { 630 error_f("confirm already set"); 631 r = SSH_ERR_INVALID_FORMAT; 632 goto out; 633 } 634 *confirmp = 1; 635 break; 636 case SSH_AGENT_CONSTRAIN_MAXSIGN: 637 if (k == NULL) { 638 error_f("maxsign not valid here"); 639 r = SSH_ERR_INVALID_FORMAT; 640 goto out; 641 } 642 if (maxsign != 0) { 643 error_f("maxsign already set"); 644 r = SSH_ERR_INVALID_FORMAT; 645 goto out; 646 } 647 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 648 error_fr(r, "parse maxsign constraint"); 649 goto out; 650 } 651 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 652 error_fr(r, "enable maxsign"); 653 goto out; 654 } 655 break; 656 case SSH_AGENT_CONSTRAIN_EXTENSION: 657 if ((r = parse_key_constraint_extension(m, 658 sk_providerp)) != 0) 659 goto out; /* error already logged */ 660 break; 661 default: 662 error_f("Unknown constraint %d", ctype); 663 r = SSH_ERR_FEATURE_UNSUPPORTED; 664 goto out; 665 } 666 } 667 /* success */ 668 r = 0; 669 out: 670 return r; 671 } 672 673 static void 674 process_add_identity(SocketEntry *e) 675 { 676 Identity *id; 677 int success = 0, confirm = 0; 678 char *fp, *comment = NULL, *sk_provider = NULL; 679 char canonical_provider[PATH_MAX]; 680 time_t death = 0; 681 u_int seconds = 0; 682 struct sshkey *k = NULL; 683 int r = SSH_ERR_INTERNAL_ERROR; 684 685 debug2_f("entering"); 686 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 687 k == NULL || 688 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 689 error_fr(r, "parse"); 690 goto out; 691 } 692 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 693 &sk_provider) != 0) { 694 error_f("failed to parse constraints"); 695 sshbuf_reset(e->request); 696 goto out; 697 } 698 699 if (sk_provider != NULL) { 700 if (!sshkey_is_sk(k)) { 701 error("Cannot add provider: %s is not an " 702 "authenticator-hosted key", sshkey_type(k)); 703 goto out; 704 } 705 if (strcasecmp(sk_provider, "internal") == 0) { 706 debug_f("internal provider"); 707 } else { 708 if (realpath(sk_provider, canonical_provider) == NULL) { 709 verbose("failed provider \"%.100s\": " 710 "realpath: %s", sk_provider, 711 strerror(errno)); 712 goto out; 713 } 714 free(sk_provider); 715 sk_provider = xstrdup(canonical_provider); 716 if (match_pattern_list(sk_provider, 717 allowed_providers, 0) != 1) { 718 error("Refusing add key: " 719 "provider %s not allowed", sk_provider); 720 goto out; 721 } 722 } 723 } 724 if ((r = sshkey_shield_private(k)) != 0) { 725 error_fr(r, "shield private"); 726 goto out; 727 } 728 if (lifetime && !death) 729 death = monotime() + lifetime; 730 if ((id = lookup_identity(k)) == NULL) { 731 id = xcalloc(1, sizeof(Identity)); 732 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 733 /* Increment the number of identities. */ 734 idtab->nentries++; 735 } else { 736 /* key state might have been updated */ 737 sshkey_free(id->key); 738 free(id->comment); 739 free(id->sk_provider); 740 } 741 /* success */ 742 id->key = k; 743 id->comment = comment; 744 id->death = death; 745 id->confirm = confirm; 746 id->sk_provider = sk_provider; 747 748 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 749 SSH_FP_DEFAULT)) == NULL) 750 fatal_f("sshkey_fingerprint failed"); 751 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 752 "(provider: %s)", sshkey_ssh_name(k), fp, comment, seconds, 753 confirm, sk_provider == NULL ? "none" : sk_provider); 754 free(fp); 755 /* transferred */ 756 k = NULL; 757 comment = NULL; 758 sk_provider = NULL; 759 success = 1; 760 out: 761 free(sk_provider); 762 free(comment); 763 sshkey_free(k); 764 send_status(e, success); 765 } 766 767 /* XXX todo: encrypt sensitive data with passphrase */ 768 static void 769 process_lock_agent(SocketEntry *e, int lock) 770 { 771 int r, success = 0, delay; 772 char *passwd; 773 u_char passwdhash[LOCK_SIZE]; 774 static u_int fail_count = 0; 775 size_t pwlen; 776 777 debug2_f("entering"); 778 /* 779 * This is deliberately fatal: the user has requested that we lock, 780 * but we can't parse their request properly. The only safe thing to 781 * do is abort. 782 */ 783 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 784 fatal_fr(r, "parse"); 785 if (pwlen == 0) { 786 debug("empty password not supported"); 787 } else if (locked && !lock) { 788 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 789 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 790 fatal("bcrypt_pbkdf"); 791 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 792 debug("agent unlocked"); 793 locked = 0; 794 fail_count = 0; 795 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 796 success = 1; 797 } else { 798 /* delay in 0.1s increments up to 10s */ 799 if (fail_count < 100) 800 fail_count++; 801 delay = 100000 * fail_count; 802 debug("unlock failed, delaying %0.1lf seconds", 803 (double)delay/1000000); 804 usleep(delay); 805 } 806 explicit_bzero(passwdhash, sizeof(passwdhash)); 807 } else if (!locked && lock) { 808 debug("agent locked"); 809 locked = 1; 810 arc4random_buf(lock_salt, sizeof(lock_salt)); 811 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 812 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 813 fatal("bcrypt_pbkdf"); 814 success = 1; 815 } 816 freezero(passwd, pwlen); 817 send_status(e, success); 818 } 819 820 static void 821 no_identities(SocketEntry *e) 822 { 823 struct sshbuf *msg; 824 int r; 825 826 if ((msg = sshbuf_new()) == NULL) 827 fatal_f("sshbuf_new failed"); 828 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 829 (r = sshbuf_put_u32(msg, 0)) != 0 || 830 (r = sshbuf_put_stringb(e->output, msg)) != 0) 831 fatal_fr(r, "compose"); 832 sshbuf_free(msg); 833 } 834 835 #ifdef ENABLE_PKCS11 836 static void 837 process_add_smartcard_key(SocketEntry *e) 838 { 839 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 840 char **comments = NULL; 841 int r, i, count = 0, success = 0, confirm = 0; 842 u_int seconds = 0; 843 time_t death = 0; 844 struct sshkey **keys = NULL, *k; 845 Identity *id; 846 847 debug2_f("entering"); 848 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 849 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 850 error_fr(r, "parse"); 851 goto send; 852 } 853 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 854 NULL) != 0) { 855 error_f("failed to parse constraints"); 856 goto send; 857 } 858 if (realpath(provider, canonical_provider) == NULL) { 859 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 860 provider, strerror(errno)); 861 goto send; 862 } 863 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 864 verbose("refusing PKCS#11 add of \"%.100s\": " 865 "provider not allowed", canonical_provider); 866 goto send; 867 } 868 debug_f("add %.100s", canonical_provider); 869 if (lifetime && !death) 870 death = monotime() + lifetime; 871 872 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 873 for (i = 0; i < count; i++) { 874 k = keys[i]; 875 if (lookup_identity(k) == NULL) { 876 id = xcalloc(1, sizeof(Identity)); 877 id->key = k; 878 keys[i] = NULL; /* transferred */ 879 id->provider = xstrdup(canonical_provider); 880 if (*comments[i] != '\0') { 881 id->comment = comments[i]; 882 comments[i] = NULL; /* transferred */ 883 } else { 884 id->comment = xstrdup(canonical_provider); 885 } 886 id->death = death; 887 id->confirm = confirm; 888 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 889 idtab->nentries++; 890 success = 1; 891 } 892 /* XXX update constraints for existing keys */ 893 sshkey_free(keys[i]); 894 free(comments[i]); 895 } 896 send: 897 free(pin); 898 free(provider); 899 free(keys); 900 free(comments); 901 send_status(e, success); 902 } 903 904 static void 905 process_remove_smartcard_key(SocketEntry *e) 906 { 907 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 908 int r, success = 0; 909 Identity *id, *nxt; 910 911 debug2_f("entering"); 912 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 913 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 914 error_fr(r, "parse"); 915 goto send; 916 } 917 free(pin); 918 919 if (realpath(provider, canonical_provider) == NULL) { 920 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 921 provider, strerror(errno)); 922 goto send; 923 } 924 925 debug_f("remove %.100s", canonical_provider); 926 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 927 nxt = TAILQ_NEXT(id, next); 928 /* Skip file--based keys */ 929 if (id->provider == NULL) 930 continue; 931 if (!strcmp(canonical_provider, id->provider)) { 932 TAILQ_REMOVE(&idtab->idlist, id, next); 933 free_identity(id); 934 idtab->nentries--; 935 } 936 } 937 if (pkcs11_del_provider(canonical_provider) == 0) 938 success = 1; 939 else 940 error_f("pkcs11_del_provider failed"); 941 send: 942 free(provider); 943 send_status(e, success); 944 } 945 #endif /* ENABLE_PKCS11 */ 946 947 /* 948 * dispatch incoming message. 949 * returns 1 on success, 0 for incomplete messages or -1 on error. 950 */ 951 static int 952 process_message(u_int socknum) 953 { 954 u_int msg_len; 955 u_char type; 956 const u_char *cp; 957 int r; 958 SocketEntry *e; 959 960 if (socknum >= sockets_alloc) 961 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 962 e = &sockets[socknum]; 963 964 if (sshbuf_len(e->input) < 5) 965 return 0; /* Incomplete message header. */ 966 cp = sshbuf_ptr(e->input); 967 msg_len = PEEK_U32(cp); 968 if (msg_len > AGENT_MAX_LEN) { 969 debug_f("socket %u (fd=%d) message too long %u > %u", 970 socknum, e->fd, msg_len, AGENT_MAX_LEN); 971 return -1; 972 } 973 if (sshbuf_len(e->input) < msg_len + 4) 974 return 0; /* Incomplete message body. */ 975 976 /* move the current input to e->request */ 977 sshbuf_reset(e->request); 978 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 979 (r = sshbuf_get_u8(e->request, &type)) != 0) { 980 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 981 r == SSH_ERR_STRING_TOO_LARGE) { 982 error_fr(r, "parse"); 983 return -1; 984 } 985 fatal_fr(r, "parse"); 986 } 987 988 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 989 990 /* check whether agent is locked */ 991 if (locked && type != SSH_AGENTC_UNLOCK) { 992 sshbuf_reset(e->request); 993 switch (type) { 994 case SSH2_AGENTC_REQUEST_IDENTITIES: 995 /* send empty lists */ 996 no_identities(e); 997 break; 998 default: 999 /* send a fail message for all other request types */ 1000 send_status(e, 0); 1001 } 1002 return 1; 1003 } 1004 1005 switch (type) { 1006 case SSH_AGENTC_LOCK: 1007 case SSH_AGENTC_UNLOCK: 1008 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1009 break; 1010 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1011 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1012 break; 1013 /* ssh2 */ 1014 case SSH2_AGENTC_SIGN_REQUEST: 1015 process_sign_request2(e); 1016 break; 1017 case SSH2_AGENTC_REQUEST_IDENTITIES: 1018 process_request_identities(e); 1019 break; 1020 case SSH2_AGENTC_ADD_IDENTITY: 1021 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1022 process_add_identity(e); 1023 break; 1024 case SSH2_AGENTC_REMOVE_IDENTITY: 1025 process_remove_identity(e); 1026 break; 1027 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1028 process_remove_all_identities(e); 1029 break; 1030 #ifdef ENABLE_PKCS11 1031 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1032 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1033 process_add_smartcard_key(e); 1034 break; 1035 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1036 process_remove_smartcard_key(e); 1037 break; 1038 #endif /* ENABLE_PKCS11 */ 1039 default: 1040 /* Unknown message. Respond with failure. */ 1041 error("Unknown message %d", type); 1042 sshbuf_reset(e->request); 1043 send_status(e, 0); 1044 break; 1045 } 1046 return 1; 1047 } 1048 1049 static void 1050 new_socket(sock_type type, int fd) 1051 { 1052 u_int i, old_alloc, new_alloc; 1053 1054 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1055 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1056 set_nonblock(fd); 1057 1058 if (fd > max_fd) 1059 max_fd = fd; 1060 1061 for (i = 0; i < sockets_alloc; i++) 1062 if (sockets[i].type == AUTH_UNUSED) { 1063 sockets[i].fd = fd; 1064 if ((sockets[i].input = sshbuf_new()) == NULL || 1065 (sockets[i].output = sshbuf_new()) == NULL || 1066 (sockets[i].request = sshbuf_new()) == NULL) 1067 fatal_f("sshbuf_new failed"); 1068 sockets[i].type = type; 1069 return; 1070 } 1071 old_alloc = sockets_alloc; 1072 new_alloc = sockets_alloc + 10; 1073 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1074 sizeof(sockets[0])); 1075 for (i = old_alloc; i < new_alloc; i++) 1076 sockets[i].type = AUTH_UNUSED; 1077 sockets_alloc = new_alloc; 1078 sockets[old_alloc].fd = fd; 1079 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1080 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1081 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1082 fatal_f("sshbuf_new failed"); 1083 sockets[old_alloc].type = type; 1084 } 1085 1086 static int 1087 handle_socket_read(u_int socknum) 1088 { 1089 struct sockaddr_un sunaddr; 1090 socklen_t slen; 1091 uid_t euid; 1092 gid_t egid; 1093 int fd; 1094 1095 slen = sizeof(sunaddr); 1096 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1097 if (fd == -1) { 1098 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1099 return -1; 1100 } 1101 if (getpeereid(fd, &euid, &egid) == -1) { 1102 error("getpeereid %d failed: %s", fd, strerror(errno)); 1103 close(fd); 1104 return -1; 1105 } 1106 if ((euid != 0) && (getuid() != euid)) { 1107 error("uid mismatch: peer euid %u != uid %u", 1108 (u_int) euid, (u_int) getuid()); 1109 close(fd); 1110 return -1; 1111 } 1112 new_socket(AUTH_CONNECTION, fd); 1113 return 0; 1114 } 1115 1116 static int 1117 handle_conn_read(u_int socknum) 1118 { 1119 char buf[AGENT_RBUF_LEN]; 1120 ssize_t len; 1121 int r; 1122 1123 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1124 if (len == -1) { 1125 if (errno == EAGAIN || errno == EINTR) 1126 return 0; 1127 error_f("read error on socket %u (fd %d): %s", 1128 socknum, sockets[socknum].fd, strerror(errno)); 1129 } 1130 return -1; 1131 } 1132 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1133 fatal_fr(r, "compose"); 1134 explicit_bzero(buf, sizeof(buf)); 1135 for (;;) { 1136 if ((r = process_message(socknum)) == -1) 1137 return -1; 1138 else if (r == 0) 1139 break; 1140 } 1141 return 0; 1142 } 1143 1144 static int 1145 handle_conn_write(u_int socknum) 1146 { 1147 ssize_t len; 1148 int r; 1149 1150 if (sshbuf_len(sockets[socknum].output) == 0) 1151 return 0; /* shouldn't happen */ 1152 if ((len = write(sockets[socknum].fd, 1153 sshbuf_ptr(sockets[socknum].output), 1154 sshbuf_len(sockets[socknum].output))) <= 0) { 1155 if (len == -1) { 1156 if (errno == EAGAIN || errno == EINTR) 1157 return 0; 1158 error_f("read error on socket %u (fd %d): %s", 1159 socknum, sockets[socknum].fd, strerror(errno)); 1160 } 1161 return -1; 1162 } 1163 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1164 fatal_fr(r, "consume"); 1165 return 0; 1166 } 1167 1168 static void 1169 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1170 { 1171 size_t i; 1172 u_int socknum, activefds = npfd; 1173 1174 for (i = 0; i < npfd; i++) { 1175 if (pfd[i].revents == 0) 1176 continue; 1177 /* Find sockets entry */ 1178 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1179 if (sockets[socknum].type != AUTH_SOCKET && 1180 sockets[socknum].type != AUTH_CONNECTION) 1181 continue; 1182 if (pfd[i].fd == sockets[socknum].fd) 1183 break; 1184 } 1185 if (socknum >= sockets_alloc) { 1186 error_f("no socket for fd %d", pfd[i].fd); 1187 continue; 1188 } 1189 /* Process events */ 1190 switch (sockets[socknum].type) { 1191 case AUTH_SOCKET: 1192 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1193 break; 1194 if (npfd > maxfds) { 1195 debug3("out of fds (active %u >= limit %u); " 1196 "skipping accept", activefds, maxfds); 1197 break; 1198 } 1199 if (handle_socket_read(socknum) == 0) 1200 activefds++; 1201 break; 1202 case AUTH_CONNECTION: 1203 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1204 handle_conn_read(socknum) != 0) 1205 goto close_sock; 1206 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1207 handle_conn_write(socknum) != 0) { 1208 close_sock: 1209 if (activefds == 0) 1210 fatal("activefds == 0 at close_sock"); 1211 close_socket(&sockets[socknum]); 1212 activefds--; 1213 break; 1214 } 1215 break; 1216 default: 1217 break; 1218 } 1219 } 1220 } 1221 1222 static int 1223 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1224 { 1225 struct pollfd *pfd = *pfdp; 1226 size_t i, j, npfd = 0; 1227 time_t deadline; 1228 int r; 1229 1230 /* Count active sockets */ 1231 for (i = 0; i < sockets_alloc; i++) { 1232 switch (sockets[i].type) { 1233 case AUTH_SOCKET: 1234 case AUTH_CONNECTION: 1235 npfd++; 1236 break; 1237 case AUTH_UNUSED: 1238 break; 1239 default: 1240 fatal("Unknown socket type %d", sockets[i].type); 1241 break; 1242 } 1243 } 1244 if (npfd != *npfdp && 1245 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1246 fatal_f("recallocarray failed"); 1247 *pfdp = pfd; 1248 *npfdp = npfd; 1249 1250 for (i = j = 0; i < sockets_alloc; i++) { 1251 switch (sockets[i].type) { 1252 case AUTH_SOCKET: 1253 if (npfd > maxfds) { 1254 debug3("out of fds (active %zu >= limit %u); " 1255 "skipping arming listener", npfd, maxfds); 1256 break; 1257 } 1258 pfd[j].fd = sockets[i].fd; 1259 pfd[j].revents = 0; 1260 pfd[j].events = POLLIN; 1261 j++; 1262 break; 1263 case AUTH_CONNECTION: 1264 pfd[j].fd = sockets[i].fd; 1265 pfd[j].revents = 0; 1266 /* 1267 * Only prepare to read if we can handle a full-size 1268 * input read buffer and enqueue a max size reply.. 1269 */ 1270 if ((r = sshbuf_check_reserve(sockets[i].input, 1271 AGENT_RBUF_LEN)) == 0 && 1272 (r = sshbuf_check_reserve(sockets[i].output, 1273 AGENT_MAX_LEN)) == 0) 1274 pfd[j].events = POLLIN; 1275 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1276 fatal_fr(r, "reserve"); 1277 if (sshbuf_len(sockets[i].output) > 0) 1278 pfd[j].events |= POLLOUT; 1279 j++; 1280 break; 1281 default: 1282 break; 1283 } 1284 } 1285 deadline = reaper(); 1286 if (parent_alive_interval != 0) 1287 deadline = (deadline == 0) ? parent_alive_interval : 1288 MINIMUM(deadline, parent_alive_interval); 1289 if (deadline == 0) { 1290 *timeoutp = -1; /* INFTIM */ 1291 } else { 1292 if (deadline > INT_MAX / 1000) 1293 *timeoutp = INT_MAX / 1000; 1294 else 1295 *timeoutp = deadline * 1000; 1296 } 1297 return (1); 1298 } 1299 1300 static void 1301 cleanup_socket(void) 1302 { 1303 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1304 return; 1305 debug_f("cleanup"); 1306 if (socket_name[0]) 1307 unlink(socket_name); 1308 if (socket_dir[0]) 1309 rmdir(socket_dir); 1310 } 1311 1312 void 1313 cleanup_exit(int i) 1314 { 1315 cleanup_socket(); 1316 _exit(i); 1317 } 1318 1319 /*ARGSUSED*/ 1320 static void 1321 cleanup_handler(int sig) 1322 { 1323 cleanup_socket(); 1324 #ifdef ENABLE_PKCS11 1325 pkcs11_terminate(); 1326 #endif 1327 _exit(2); 1328 } 1329 1330 static void 1331 check_parent_exists(void) 1332 { 1333 /* 1334 * If our parent has exited then getppid() will return (pid_t)1, 1335 * so testing for that should be safe. 1336 */ 1337 if (parent_pid != -1 && getppid() != parent_pid) { 1338 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1339 cleanup_socket(); 1340 _exit(2); 1341 } 1342 } 1343 1344 static void 1345 usage(void) 1346 { 1347 fprintf(stderr, 1348 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1349 " [-P allowed_providers] [-t life]\n" 1350 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1351 " [-t life] command [arg ...]\n" 1352 " ssh-agent [-c | -s] -k\n"); 1353 exit(1); 1354 } 1355 1356 int 1357 main(int ac, char **av) 1358 { 1359 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1360 int sock, ch, result, saved_errno; 1361 char *shell, *format, *pidstr, *agentsocket = NULL; 1362 struct rlimit rlim; 1363 extern int optind; 1364 extern char *optarg; 1365 pid_t pid; 1366 char pidstrbuf[1 + 3 * sizeof pid]; 1367 size_t len; 1368 mode_t prev_mask; 1369 int timeout = -1; /* INFTIM */ 1370 struct pollfd *pfd = NULL; 1371 size_t npfd = 0; 1372 u_int maxfds; 1373 1374 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1375 sanitise_stdfd(); 1376 1377 /* drop */ 1378 setegid(getgid()); 1379 setgid(getgid()); 1380 1381 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1382 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1383 1384 #ifdef WITH_OPENSSL 1385 OpenSSL_add_all_algorithms(); 1386 #endif 1387 1388 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1389 switch (ch) { 1390 case 'E': 1391 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1392 if (fingerprint_hash == -1) 1393 fatal("Invalid hash algorithm \"%s\"", optarg); 1394 break; 1395 case 'c': 1396 if (s_flag) 1397 usage(); 1398 c_flag++; 1399 break; 1400 case 'k': 1401 k_flag++; 1402 break; 1403 case 'O': 1404 if (strcmp(optarg, "no-restrict-websafe") == 0) 1405 restrict_websafe = 0; 1406 else 1407 fatal("Unknown -O option"); 1408 break; 1409 case 'P': 1410 if (allowed_providers != NULL) 1411 fatal("-P option already specified"); 1412 allowed_providers = xstrdup(optarg); 1413 break; 1414 case 's': 1415 if (c_flag) 1416 usage(); 1417 s_flag++; 1418 break; 1419 case 'd': 1420 if (d_flag || D_flag) 1421 usage(); 1422 d_flag++; 1423 break; 1424 case 'D': 1425 if (d_flag || D_flag) 1426 usage(); 1427 D_flag++; 1428 break; 1429 case 'a': 1430 agentsocket = optarg; 1431 break; 1432 case 't': 1433 if ((lifetime = convtime(optarg)) == -1) { 1434 fprintf(stderr, "Invalid lifetime\n"); 1435 usage(); 1436 } 1437 break; 1438 default: 1439 usage(); 1440 } 1441 } 1442 ac -= optind; 1443 av += optind; 1444 1445 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1446 usage(); 1447 1448 if (allowed_providers == NULL) 1449 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1450 1451 if (ac == 0 && !c_flag && !s_flag) { 1452 shell = getenv("SHELL"); 1453 if (shell != NULL && (len = strlen(shell)) > 2 && 1454 strncmp(shell + len - 3, "csh", 3) == 0) 1455 c_flag = 1; 1456 } 1457 if (k_flag) { 1458 const char *errstr = NULL; 1459 1460 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1461 if (pidstr == NULL) { 1462 fprintf(stderr, "%s not set, cannot kill agent\n", 1463 SSH_AGENTPID_ENV_NAME); 1464 exit(1); 1465 } 1466 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1467 if (errstr) { 1468 fprintf(stderr, 1469 "%s=\"%s\", which is not a good PID: %s\n", 1470 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1471 exit(1); 1472 } 1473 if (kill(pid, SIGTERM) == -1) { 1474 perror("kill"); 1475 exit(1); 1476 } 1477 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 1478 printf(format, SSH_AUTHSOCKET_ENV_NAME); 1479 printf(format, SSH_AGENTPID_ENV_NAME); 1480 printf("echo Agent pid %ld killed;\n", (long)pid); 1481 exit(0); 1482 } 1483 1484 /* 1485 * Minimum file descriptors: 1486 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1487 * a few spare for libc / stack protectors / sanitisers, etc. 1488 */ 1489 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1490 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1491 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1492 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1493 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1494 1495 parent_pid = getpid(); 1496 1497 if (agentsocket == NULL) { 1498 /* Create private directory for agent socket */ 1499 mktemp_proto(socket_dir, sizeof(socket_dir)); 1500 if (mkdtemp(socket_dir) == NULL) { 1501 perror("mkdtemp: private socket dir"); 1502 exit(1); 1503 } 1504 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1505 (long)parent_pid); 1506 } else { 1507 /* Try to use specified agent socket */ 1508 socket_dir[0] = '\0'; 1509 strlcpy(socket_name, agentsocket, sizeof socket_name); 1510 } 1511 1512 /* 1513 * Create socket early so it will exist before command gets run from 1514 * the parent. 1515 */ 1516 prev_mask = umask(0177); 1517 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1518 if (sock < 0) { 1519 /* XXX - unix_listener() calls error() not perror() */ 1520 *socket_name = '\0'; /* Don't unlink any existing file */ 1521 cleanup_exit(1); 1522 } 1523 umask(prev_mask); 1524 1525 /* 1526 * Fork, and have the parent execute the command, if any, or present 1527 * the socket data. The child continues as the authentication agent. 1528 */ 1529 if (D_flag || d_flag) { 1530 log_init(__progname, 1531 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1532 SYSLOG_FACILITY_AUTH, 1); 1533 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1534 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1535 SSH_AUTHSOCKET_ENV_NAME); 1536 printf("echo Agent pid %ld;\n", (long)parent_pid); 1537 fflush(stdout); 1538 goto skip; 1539 } 1540 pid = fork(); 1541 if (pid == -1) { 1542 perror("fork"); 1543 cleanup_exit(1); 1544 } 1545 if (pid != 0) { /* Parent - execute the given command. */ 1546 close(sock); 1547 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1548 if (ac == 0) { 1549 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 1550 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 1551 SSH_AUTHSOCKET_ENV_NAME); 1552 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 1553 SSH_AGENTPID_ENV_NAME); 1554 printf("echo Agent pid %ld;\n", (long)pid); 1555 exit(0); 1556 } 1557 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1558 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1559 perror("setenv"); 1560 exit(1); 1561 } 1562 execvp(av[0], av); 1563 perror(av[0]); 1564 exit(1); 1565 } 1566 /* child */ 1567 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1568 1569 if (setsid() == -1) { 1570 error("setsid: %s", strerror(errno)); 1571 cleanup_exit(1); 1572 } 1573 1574 (void)chdir("/"); 1575 if (stdfd_devnull(1, 1, 1) == -1) 1576 error_f("stdfd_devnull failed"); 1577 1578 /* deny core dumps, since memory contains unencrypted private keys */ 1579 rlim.rlim_cur = rlim.rlim_max = 0; 1580 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1581 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1582 cleanup_exit(1); 1583 } 1584 1585 skip: 1586 1587 cleanup_pid = getpid(); 1588 1589 #ifdef ENABLE_PKCS11 1590 pkcs11_init(0); 1591 #endif 1592 new_socket(AUTH_SOCKET, sock); 1593 if (ac > 0) 1594 parent_alive_interval = 10; 1595 idtab_init(); 1596 ssh_signal(SIGPIPE, SIG_IGN); 1597 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1598 ssh_signal(SIGHUP, cleanup_handler); 1599 ssh_signal(SIGTERM, cleanup_handler); 1600 1601 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1602 fatal("%s: pledge: %s", __progname, strerror(errno)); 1603 1604 while (1) { 1605 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1606 result = poll(pfd, npfd, timeout); 1607 saved_errno = errno; 1608 if (parent_alive_interval != 0) 1609 check_parent_exists(); 1610 (void) reaper(); /* remove expired keys */ 1611 if (result == -1) { 1612 if (saved_errno == EINTR) 1613 continue; 1614 fatal("poll: %s", strerror(saved_errno)); 1615 } else if (result > 0) 1616 after_poll(pfd, npfd, maxfds); 1617 } 1618 /* NOTREACHED */ 1619 } 1620