1 /* $NetBSD: ssh-agent.c,v 1.31 2021/03/05 17:47:16 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.277 2021/02/12 03:14:18 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * The authentication agent program. 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 __RCSID("$NetBSD: ssh-agent.c,v 1.31 2021/03/05 17:47:16 christos Exp $"); 41 42 #include <sys/param.h> /* MIN MAX */ 43 #include <sys/types.h> 44 #include <sys/time.h> 45 #include <sys/queue.h> 46 #include <sys/resource.h> 47 #include <sys/socket.h> 48 #include <sys/stat.h> 49 #include <sys/un.h> 50 #include <sys/wait.h> 51 52 #ifdef WITH_OPENSSL 53 #include <openssl/evp.h> 54 #endif 55 56 #include <errno.h> 57 #include <fcntl.h> 58 #include <paths.h> 59 #include <poll.h> 60 #include <signal.h> 61 #include <stdlib.h> 62 #include <stdio.h> 63 #include <string.h> 64 #include <stdarg.h> 65 #include <limits.h> 66 #include <time.h> 67 #include <unistd.h> 68 #include <util.h> 69 70 #include "xmalloc.h" 71 #include "ssh.h" 72 #include "ssh2.h" 73 #include "sshbuf.h" 74 #include "sshkey.h" 75 #include "authfd.h" 76 #include "compat.h" 77 #include "log.h" 78 #include "misc.h" 79 #include "getpeereid.h" 80 #include "digest.h" 81 #include "ssherr.h" 82 #include "match.h" 83 #include "msg.h" 84 #include "ssherr.h" 85 #include "pathnames.h" 86 #include "ssh-pkcs11.h" 87 #include "sk-api.h" 88 89 #ifndef DEFAULT_ALLOWED_PROVIDERS 90 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/pkg/lib*/*" 91 #endif 92 93 /* Maximum accepted message length */ 94 #define AGENT_MAX_LEN (256*1024) 95 /* Maximum bytes to read from client socket */ 96 #define AGENT_RBUF_LEN (4096) 97 98 typedef enum { 99 AUTH_UNUSED = 0, 100 AUTH_SOCKET = 1, 101 AUTH_CONNECTION = 2, 102 } sock_type; 103 104 typedef struct socket_entry { 105 int fd; 106 sock_type type; 107 struct sshbuf *input; 108 struct sshbuf *output; 109 struct sshbuf *request; 110 } SocketEntry; 111 112 u_int sockets_alloc = 0; 113 SocketEntry *sockets = NULL; 114 115 typedef struct identity { 116 TAILQ_ENTRY(identity) next; 117 struct sshkey *key; 118 char *comment; 119 char *provider; 120 time_t death; 121 u_int confirm; 122 char *sk_provider; 123 } Identity; 124 125 struct idtable { 126 int nentries; 127 TAILQ_HEAD(idqueue, identity) idlist; 128 }; 129 130 /* private key table */ 131 struct idtable *idtab; 132 133 int max_fd = 0; 134 135 /* pid of shell == parent of agent */ 136 pid_t parent_pid = -1; 137 time_t parent_alive_interval = 0; 138 139 /* pid of process for which cleanup_socket is applicable */ 140 pid_t cleanup_pid = 0; 141 142 /* pathname and directory for AUTH_SOCKET */ 143 char socket_name[PATH_MAX]; 144 char socket_dir[PATH_MAX]; 145 146 /* Pattern-list of allowed PKCS#11/Security key paths */ 147 static char *allowed_providers; 148 149 /* locking */ 150 #define LOCK_SIZE 32 151 #define LOCK_SALT_SIZE 16 152 #define LOCK_ROUNDS 1 153 int locked = 0; 154 u_char lock_pwhash[LOCK_SIZE]; 155 u_char lock_salt[LOCK_SALT_SIZE]; 156 157 extern char *__progname; 158 159 /* Default lifetime in seconds (0 == forever) */ 160 static int lifetime = 0; 161 162 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 163 164 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 165 static int restrict_websafe = 1; 166 167 static void 168 close_socket(SocketEntry *e) 169 { 170 close(e->fd); 171 sshbuf_free(e->input); 172 sshbuf_free(e->output); 173 sshbuf_free(e->request); 174 memset(e, '\0', sizeof(*e)); 175 e->fd = -1; 176 e->type = AUTH_UNUSED; 177 } 178 179 static void 180 idtab_init(void) 181 { 182 idtab = xcalloc(1, sizeof(*idtab)); 183 TAILQ_INIT(&idtab->idlist); 184 idtab->nentries = 0; 185 } 186 187 static void 188 free_identity(Identity *id) 189 { 190 sshkey_free(id->key); 191 free(id->provider); 192 free(id->comment); 193 free(id->sk_provider); 194 free(id); 195 } 196 197 /* return matching private key for given public key */ 198 static Identity * 199 lookup_identity(struct sshkey *key) 200 { 201 Identity *id; 202 203 TAILQ_FOREACH(id, &idtab->idlist, next) { 204 if (sshkey_equal(key, id->key)) 205 return (id); 206 } 207 return (NULL); 208 } 209 210 /* Check confirmation of keysign request */ 211 static int 212 confirm_key(Identity *id, const char *extra) 213 { 214 char *p; 215 int ret = -1; 216 217 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 218 if (p != NULL && 219 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 220 id->comment, p, 221 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 222 ret = 0; 223 free(p); 224 225 return (ret); 226 } 227 228 static void 229 send_status(SocketEntry *e, int success) 230 { 231 int r; 232 233 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 234 (r = sshbuf_put_u8(e->output, success ? 235 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 236 fatal_fr(r, "compose"); 237 } 238 239 /* send list of supported public keys to 'client' */ 240 static void 241 process_request_identities(SocketEntry *e) 242 { 243 Identity *id; 244 struct sshbuf *msg; 245 int r; 246 247 debug2_f("entering"); 248 249 if ((msg = sshbuf_new()) == NULL) 250 fatal_f("sshbuf_new failed"); 251 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 252 (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) 253 fatal_fr(r, "compose"); 254 TAILQ_FOREACH(id, &idtab->idlist, next) { 255 if ((r = sshkey_puts_opts(id->key, msg, SSHKEY_SERIALIZE_INFO)) 256 != 0 || 257 (r = sshbuf_put_cstring(msg, id->comment)) != 0) { 258 error_fr(r, "compose key/comment"); 259 continue; 260 } 261 } 262 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 263 fatal_fr(r, "enqueue"); 264 sshbuf_free(msg); 265 } 266 267 268 static const char * 269 agent_decode_alg(struct sshkey *key, u_int flags) 270 { 271 if (key->type == KEY_RSA) { 272 if (flags & SSH_AGENT_RSA_SHA2_256) 273 return "rsa-sha2-256"; 274 else if (flags & SSH_AGENT_RSA_SHA2_512) 275 return "rsa-sha2-512"; 276 } else if (key->type == KEY_RSA_CERT) { 277 if (flags & SSH_AGENT_RSA_SHA2_256) 278 return "rsa-sha2-256-cert-v01@openssh.com"; 279 else if (flags & SSH_AGENT_RSA_SHA2_512) 280 return "rsa-sha2-512-cert-v01@openssh.com"; 281 } 282 return NULL; 283 } 284 285 /* 286 * Attempt to parse the contents of a buffer as a SSH publickey userauth 287 * request, checking its contents for consistency and matching the embedded 288 * key against the one that is being used for signing. 289 * Note: does not modify msg buffer. 290 * Optionally extract the username and session ID from the request. 291 */ 292 static int 293 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 294 char **userp, struct sshbuf **sess_idp) 295 { 296 struct sshbuf *b = NULL, *sess_id = NULL; 297 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 298 int r; 299 u_char t, sig_follows; 300 struct sshkey *mkey = NULL; 301 302 if (userp != NULL) 303 *userp = NULL; 304 if (sess_idp != NULL) 305 *sess_idp = NULL; 306 if ((b = sshbuf_fromb(msg)) == NULL) 307 fatal_f("sshbuf_fromb"); 308 309 /* SSH userauth request */ 310 if ((r = sshbuf_froms(b, &sess_id)) != 0) 311 goto out; 312 if (sshbuf_len(sess_id) == 0) { 313 r = SSH_ERR_INVALID_FORMAT; 314 goto out; 315 } 316 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 317 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 318 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 319 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 320 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 321 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 322 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 323 goto out; 324 if (t != SSH2_MSG_USERAUTH_REQUEST || 325 sig_follows != 1 || 326 strcmp(service, "ssh-connection") != 0 || 327 !sshkey_equal(expected_key, mkey) || 328 sshkey_type_from_name(pkalg) != expected_key->type) { 329 r = SSH_ERR_INVALID_FORMAT; 330 goto out; 331 } 332 if (strcmp(method, "publickey") != 0) { 333 r = SSH_ERR_INVALID_FORMAT; 334 goto out; 335 } 336 if (sshbuf_len(b) != 0) { 337 r = SSH_ERR_INVALID_FORMAT; 338 goto out; 339 } 340 /* success */ 341 r = 0; 342 debug3_f("well formed userauth"); 343 if (userp != NULL) { 344 *userp = user; 345 user = NULL; 346 } 347 if (sess_idp != NULL) { 348 *sess_idp = sess_id; 349 sess_id = NULL; 350 } 351 out: 352 sshbuf_free(b); 353 sshbuf_free(sess_id); 354 free(user); 355 free(service); 356 free(method); 357 free(pkalg); 358 sshkey_free(mkey); 359 return r; 360 } 361 362 /* 363 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 364 * Note: does not modify buffer. 365 */ 366 static int 367 parse_sshsig_request(struct sshbuf *msg) 368 { 369 int r; 370 struct sshbuf *b; 371 372 if ((b = sshbuf_fromb(msg)) == NULL) 373 fatal_f("sshbuf_fromb"); 374 375 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 376 (r = sshbuf_consume(b, 6)) != 0 || 377 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 378 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 379 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 380 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 381 goto out; 382 if (sshbuf_len(b) != 0) { 383 r = SSH_ERR_INVALID_FORMAT; 384 goto out; 385 } 386 /* success */ 387 r = 0; 388 out: 389 sshbuf_free(b); 390 return r; 391 } 392 393 /* 394 * This function inspects a message to be signed by a FIDO key that has a 395 * web-like application string (i.e. one that does not begin with "ssh:". 396 * It checks that the message is one of those expected for SSH operations 397 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 398 * for the web. 399 */ 400 static int 401 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 402 { 403 if (parse_userauth_request(data, key, NULL, NULL) == 0) { 404 debug_f("signed data matches public key userauth request"); 405 return 1; 406 } 407 if (parse_sshsig_request(data) == 0) { 408 debug_f("signed data matches SSHSIG signature request"); 409 return 1; 410 } 411 412 /* XXX check CA signature operation */ 413 414 error("web-origin key attempting to sign non-SSH message"); 415 return 0; 416 } 417 418 /* ssh2 only */ 419 static void 420 process_sign_request2(SocketEntry *e) 421 { 422 u_char *signature = NULL; 423 size_t slen = 0; 424 u_int compat = 0, flags; 425 int r, ok = -1; 426 char *fp = NULL; 427 struct sshbuf *msg = NULL, *data = NULL; 428 struct sshkey *key = NULL; 429 struct identity *id; 430 struct notifier_ctx *notifier = NULL; 431 432 debug_f("entering"); 433 434 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 435 fatal_f("sshbuf_new failed"); 436 if ((r = sshkey_froms(e->request, &key)) != 0 || 437 (r = sshbuf_get_stringb(e->request, data)) != 0 || 438 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 439 error_fr(r, "parse"); 440 goto send; 441 } 442 443 if ((id = lookup_identity(key)) == NULL) { 444 verbose_f("%s key not found", sshkey_type(key)); 445 goto send; 446 } 447 if (id->confirm && confirm_key(id, NULL) != 0) { 448 verbose_f("user refused key"); 449 goto send; 450 } 451 if (sshkey_is_sk(id->key)) { 452 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 453 !check_websafe_message_contents(key, data)) { 454 /* error already logged */ 455 goto send; 456 } 457 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 458 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 459 SSH_FP_DEFAULT)) == NULL) 460 fatal_f("fingerprint failed"); 461 notifier = notify_start(0, 462 "Confirm user presence for key %s %s", 463 sshkey_type(id->key), fp); 464 } 465 } 466 /* XXX support PIN required FIDO keys */ 467 if ((r = sshkey_sign(id->key, &signature, &slen, 468 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 469 id->sk_provider, NULL, compat)) != 0) { 470 error_fr(r, "sshkey_sign"); 471 goto send; 472 } 473 /* Success */ 474 ok = 0; 475 send: 476 notify_complete(notifier, "User presence confirmed"); 477 478 if (ok == 0) { 479 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 480 (r = sshbuf_put_string(msg, signature, slen)) != 0) 481 fatal_fr(r, "compose"); 482 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 483 fatal_fr(r, "compose failure"); 484 485 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 486 fatal_fr(r, "enqueue"); 487 488 sshbuf_free(data); 489 sshbuf_free(msg); 490 sshkey_free(key); 491 free(fp); 492 free(signature); 493 } 494 495 /* shared */ 496 static void 497 process_remove_identity(SocketEntry *e) 498 { 499 int r, success = 0; 500 struct sshkey *key = NULL; 501 Identity *id; 502 503 debug2_f("entering"); 504 if ((r = sshkey_froms(e->request, &key)) != 0) { 505 error_fr(r, "parse key"); 506 goto done; 507 } 508 if ((id = lookup_identity(key)) == NULL) { 509 debug_f("key not found"); 510 goto done; 511 } 512 /* We have this key, free it. */ 513 if (idtab->nentries < 1) 514 fatal_f("internal error: nentries %d", idtab->nentries); 515 TAILQ_REMOVE(&idtab->idlist, id, next); 516 free_identity(id); 517 idtab->nentries--; 518 success = 1; 519 done: 520 sshkey_free(key); 521 send_status(e, success); 522 } 523 524 static void 525 process_remove_all_identities(SocketEntry *e) 526 { 527 Identity *id; 528 529 debug2_f("entering"); 530 /* Loop over all identities and clear the keys. */ 531 for (id = TAILQ_FIRST(&idtab->idlist); id; 532 id = TAILQ_FIRST(&idtab->idlist)) { 533 TAILQ_REMOVE(&idtab->idlist, id, next); 534 free_identity(id); 535 } 536 537 /* Mark that there are no identities. */ 538 idtab->nentries = 0; 539 540 /* Send success. */ 541 send_status(e, 1); 542 } 543 544 /* removes expired keys and returns number of seconds until the next expiry */ 545 static time_t 546 reaper(void) 547 { 548 time_t deadline = 0, now = monotime(); 549 Identity *id, *nxt; 550 551 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 552 nxt = TAILQ_NEXT(id, next); 553 if (id->death == 0) 554 continue; 555 if (now >= id->death) { 556 debug("expiring key '%s'", id->comment); 557 TAILQ_REMOVE(&idtab->idlist, id, next); 558 free_identity(id); 559 idtab->nentries--; 560 } else 561 deadline = (deadline == 0) ? id->death : 562 MINIMUM(deadline, id->death); 563 } 564 if (deadline == 0 || deadline <= now) 565 return 0; 566 else 567 return (deadline - now); 568 } 569 570 static int 571 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp) 572 { 573 char *ext_name = NULL; 574 int r; 575 576 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 577 error_fr(r, "parse constraint extension"); 578 goto out; 579 } 580 debug_f("constraint ext %s", ext_name); 581 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 582 if (sk_providerp == NULL) { 583 error_f("%s not valid here", ext_name); 584 r = SSH_ERR_INVALID_FORMAT; 585 goto out; 586 } 587 if (*sk_providerp != NULL) { 588 error_f("%s already set", ext_name); 589 r = SSH_ERR_INVALID_FORMAT; 590 goto out; 591 } 592 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 593 error_fr(r, "parse %s", ext_name); 594 goto out; 595 } 596 } else { 597 error_f("unsupported constraint \"%s\"", ext_name); 598 r = SSH_ERR_FEATURE_UNSUPPORTED; 599 goto out; 600 } 601 /* success */ 602 r = 0; 603 out: 604 free(ext_name); 605 return r; 606 } 607 608 static int 609 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 610 u_int *secondsp, int *confirmp, char **sk_providerp) 611 { 612 u_char ctype; 613 int r; 614 u_int seconds, maxsign = 0; 615 616 while (sshbuf_len(m)) { 617 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 618 error_fr(r, "parse constraint type"); 619 goto out; 620 } 621 switch (ctype) { 622 case SSH_AGENT_CONSTRAIN_LIFETIME: 623 if (*deathp != 0) { 624 error_f("lifetime already set"); 625 r = SSH_ERR_INVALID_FORMAT; 626 goto out; 627 } 628 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 629 error_fr(r, "parse lifetime constraint"); 630 goto out; 631 } 632 *deathp = monotime() + seconds; 633 *secondsp = seconds; 634 break; 635 case SSH_AGENT_CONSTRAIN_CONFIRM: 636 if (*confirmp != 0) { 637 error_f("confirm already set"); 638 r = SSH_ERR_INVALID_FORMAT; 639 goto out; 640 } 641 *confirmp = 1; 642 break; 643 case SSH_AGENT_CONSTRAIN_MAXSIGN: 644 if (k == NULL) { 645 error_f("maxsign not valid here"); 646 r = SSH_ERR_INVALID_FORMAT; 647 goto out; 648 } 649 if (maxsign != 0) { 650 error_f("maxsign already set"); 651 r = SSH_ERR_INVALID_FORMAT; 652 goto out; 653 } 654 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 655 error_fr(r, "parse maxsign constraint"); 656 goto out; 657 } 658 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 659 error_fr(r, "enable maxsign"); 660 goto out; 661 } 662 break; 663 case SSH_AGENT_CONSTRAIN_EXTENSION: 664 if ((r = parse_key_constraint_extension(m, 665 sk_providerp)) != 0) 666 goto out; /* error already logged */ 667 break; 668 default: 669 error_f("Unknown constraint %d", ctype); 670 r = SSH_ERR_FEATURE_UNSUPPORTED; 671 goto out; 672 } 673 } 674 /* success */ 675 r = 0; 676 out: 677 return r; 678 } 679 680 static void 681 process_add_identity(SocketEntry *e) 682 { 683 Identity *id; 684 int success = 0, confirm = 0; 685 char *fp, *comment = NULL, *sk_provider = NULL; 686 char canonical_provider[PATH_MAX]; 687 time_t death = 0; 688 u_int seconds = 0; 689 struct sshkey *k = NULL; 690 int r = SSH_ERR_INTERNAL_ERROR; 691 692 debug2_f("entering"); 693 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 694 k == NULL || 695 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 696 error_fr(r, "parse"); 697 goto out; 698 } 699 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 700 &sk_provider) != 0) { 701 error_f("failed to parse constraints"); 702 sshbuf_reset(e->request); 703 goto out; 704 } 705 706 if (sk_provider != NULL) { 707 if (!sshkey_is_sk(k)) { 708 error("Cannot add provider: %s is not an " 709 "authenticator-hosted key", sshkey_type(k)); 710 goto out; 711 } 712 if (strcasecmp(sk_provider, "internal") == 0) { 713 debug_f("internal provider"); 714 } else { 715 if (realpath(sk_provider, canonical_provider) == NULL) { 716 verbose("failed provider \"%.100s\": " 717 "realpath: %s", sk_provider, 718 strerror(errno)); 719 goto out; 720 } 721 free(sk_provider); 722 sk_provider = xstrdup(canonical_provider); 723 if (match_pattern_list(sk_provider, 724 allowed_providers, 0) != 1) { 725 error("Refusing add key: " 726 "provider %s not allowed", sk_provider); 727 goto out; 728 } 729 } 730 } 731 if ((r = sshkey_shield_private(k)) != 0) { 732 error_fr(r, "shield private"); 733 goto out; 734 } 735 if (lifetime && !death) 736 death = monotime() + lifetime; 737 if ((id = lookup_identity(k)) == NULL) { 738 id = xcalloc(1, sizeof(Identity)); 739 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 740 /* Increment the number of identities. */ 741 idtab->nentries++; 742 } else { 743 /* key state might have been updated */ 744 sshkey_free(id->key); 745 free(id->comment); 746 free(id->sk_provider); 747 } 748 /* success */ 749 id->key = k; 750 id->comment = comment; 751 id->death = death; 752 id->confirm = confirm; 753 id->sk_provider = sk_provider; 754 755 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 756 SSH_FP_DEFAULT)) == NULL) 757 fatal_f("sshkey_fingerprint failed"); 758 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 759 "(provider: %s)", sshkey_ssh_name(k), fp, comment, seconds, 760 confirm, sk_provider == NULL ? "none" : sk_provider); 761 free(fp); 762 /* transferred */ 763 k = NULL; 764 comment = NULL; 765 sk_provider = NULL; 766 success = 1; 767 out: 768 free(sk_provider); 769 free(comment); 770 sshkey_free(k); 771 send_status(e, success); 772 } 773 774 /* XXX todo: encrypt sensitive data with passphrase */ 775 static void 776 process_lock_agent(SocketEntry *e, int lock) 777 { 778 int r, success = 0, delay; 779 char *passwd; 780 u_char passwdhash[LOCK_SIZE]; 781 static u_int fail_count = 0; 782 size_t pwlen; 783 784 debug2_f("entering"); 785 /* 786 * This is deliberately fatal: the user has requested that we lock, 787 * but we can't parse their request properly. The only safe thing to 788 * do is abort. 789 */ 790 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 791 fatal_fr(r, "parse"); 792 if (pwlen == 0) { 793 debug("empty password not supported"); 794 } else if (locked && !lock) { 795 if (bcrypt_pbkdf(passwd, pwlen, (uint8_t *)lock_salt, sizeof(lock_salt), 796 (uint8_t *)passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 797 fatal("bcrypt_pbkdf"); 798 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 799 debug("agent unlocked"); 800 locked = 0; 801 fail_count = 0; 802 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 803 success = 1; 804 } else { 805 /* delay in 0.1s increments up to 10s */ 806 if (fail_count < 100) 807 fail_count++; 808 delay = 100000 * fail_count; 809 debug("unlock failed, delaying %0.1lf seconds", 810 (double)delay/1000000); 811 usleep(delay); 812 } 813 explicit_bzero(passwdhash, sizeof(passwdhash)); 814 } else if (!locked && lock) { 815 debug("agent locked"); 816 locked = 1; 817 arc4random_buf(lock_salt, sizeof(lock_salt)); 818 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 819 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 820 fatal("bcrypt_pbkdf"); 821 success = 1; 822 } 823 freezero(passwd, pwlen); 824 send_status(e, success); 825 } 826 827 static void 828 no_identities(SocketEntry *e) 829 { 830 struct sshbuf *msg; 831 int r; 832 833 if ((msg = sshbuf_new()) == NULL) 834 fatal_f("sshbuf_new failed"); 835 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 836 (r = sshbuf_put_u32(msg, 0)) != 0 || 837 (r = sshbuf_put_stringb(e->output, msg)) != 0) 838 fatal_fr(r, "compose"); 839 sshbuf_free(msg); 840 } 841 842 #ifdef ENABLE_PKCS11 843 static void 844 process_add_smartcard_key(SocketEntry *e) 845 { 846 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 847 char **comments = NULL; 848 int r, i, count = 0, success = 0, confirm = 0; 849 u_int seconds = 0; 850 time_t death = 0; 851 struct sshkey **keys = NULL, *k; 852 Identity *id; 853 854 debug2_f("entering"); 855 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 856 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 857 error_fr(r, "parse"); 858 goto send; 859 } 860 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 861 NULL) != 0) { 862 error_f("failed to parse constraints"); 863 goto send; 864 } 865 if (realpath(provider, canonical_provider) == NULL) { 866 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 867 provider, strerror(errno)); 868 goto send; 869 } 870 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 871 verbose("refusing PKCS#11 add of \"%.100s\": " 872 "provider not allowed", canonical_provider); 873 goto send; 874 } 875 debug_f("add %.100s", canonical_provider); 876 if (lifetime && !death) 877 death = monotime() + lifetime; 878 879 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 880 for (i = 0; i < count; i++) { 881 k = keys[i]; 882 if (lookup_identity(k) == NULL) { 883 id = xcalloc(1, sizeof(Identity)); 884 id->key = k; 885 keys[i] = NULL; /* transferred */ 886 id->provider = xstrdup(canonical_provider); 887 if (*comments[i] != '\0') { 888 id->comment = comments[i]; 889 comments[i] = NULL; /* transferred */ 890 } else { 891 id->comment = xstrdup(canonical_provider); 892 } 893 id->death = death; 894 id->confirm = confirm; 895 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 896 idtab->nentries++; 897 success = 1; 898 } 899 /* XXX update constraints for existing keys */ 900 sshkey_free(keys[i]); 901 free(comments[i]); 902 } 903 send: 904 free(pin); 905 free(provider); 906 free(keys); 907 free(comments); 908 send_status(e, success); 909 } 910 911 static void 912 process_remove_smartcard_key(SocketEntry *e) 913 { 914 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 915 int r, success = 0; 916 Identity *id, *nxt; 917 918 debug2_f("entering"); 919 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 920 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 921 error_fr(r, "parse"); 922 goto send; 923 } 924 free(pin); 925 926 if (realpath(provider, canonical_provider) == NULL) { 927 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 928 provider, strerror(errno)); 929 goto send; 930 } 931 932 debug_f("remove %.100s", canonical_provider); 933 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 934 nxt = TAILQ_NEXT(id, next); 935 /* Skip file--based keys */ 936 if (id->provider == NULL) 937 continue; 938 if (!strcmp(canonical_provider, id->provider)) { 939 TAILQ_REMOVE(&idtab->idlist, id, next); 940 free_identity(id); 941 idtab->nentries--; 942 } 943 } 944 if (pkcs11_del_provider(canonical_provider) == 0) 945 success = 1; 946 else 947 error_f("pkcs11_del_provider failed"); 948 send: 949 free(provider); 950 send_status(e, success); 951 } 952 #endif /* ENABLE_PKCS11 */ 953 954 /* 955 * dispatch incoming message. 956 * returns 1 on success, 0 for incomplete messages or -1 on error. 957 */ 958 static int 959 process_message(u_int socknum) 960 { 961 u_int msg_len; 962 u_char type; 963 const u_char *cp; 964 int r; 965 SocketEntry *e; 966 967 if (socknum >= sockets_alloc) 968 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 969 e = &sockets[socknum]; 970 971 if (sshbuf_len(e->input) < 5) 972 return 0; /* Incomplete message header. */ 973 cp = sshbuf_ptr(e->input); 974 msg_len = PEEK_U32(cp); 975 if (msg_len > AGENT_MAX_LEN) { 976 debug_f("socket %u (fd=%d) message too long %u > %u", 977 socknum, e->fd, msg_len, AGENT_MAX_LEN); 978 return -1; 979 } 980 if (sshbuf_len(e->input) < msg_len + 4) 981 return 0; /* Incomplete message body. */ 982 983 /* move the current input to e->request */ 984 sshbuf_reset(e->request); 985 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 986 (r = sshbuf_get_u8(e->request, &type)) != 0) { 987 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 988 r == SSH_ERR_STRING_TOO_LARGE) { 989 error_fr(r, "parse"); 990 return -1; 991 } 992 fatal_fr(r, "parse"); 993 } 994 995 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 996 997 /* check whether agent is locked */ 998 if (locked && type != SSH_AGENTC_UNLOCK) { 999 sshbuf_reset(e->request); 1000 switch (type) { 1001 case SSH2_AGENTC_REQUEST_IDENTITIES: 1002 /* send empty lists */ 1003 no_identities(e); 1004 break; 1005 default: 1006 /* send a fail message for all other request types */ 1007 send_status(e, 0); 1008 } 1009 return 1; 1010 } 1011 1012 switch (type) { 1013 case SSH_AGENTC_LOCK: 1014 case SSH_AGENTC_UNLOCK: 1015 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1016 break; 1017 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1018 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1019 break; 1020 /* ssh2 */ 1021 case SSH2_AGENTC_SIGN_REQUEST: 1022 process_sign_request2(e); 1023 break; 1024 case SSH2_AGENTC_REQUEST_IDENTITIES: 1025 process_request_identities(e); 1026 break; 1027 case SSH2_AGENTC_ADD_IDENTITY: 1028 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1029 process_add_identity(e); 1030 break; 1031 case SSH2_AGENTC_REMOVE_IDENTITY: 1032 process_remove_identity(e); 1033 break; 1034 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1035 process_remove_all_identities(e); 1036 break; 1037 #ifdef ENABLE_PKCS11 1038 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1039 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1040 process_add_smartcard_key(e); 1041 break; 1042 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1043 process_remove_smartcard_key(e); 1044 break; 1045 #endif /* ENABLE_PKCS11 */ 1046 default: 1047 /* Unknown message. Respond with failure. */ 1048 error("Unknown message %d", type); 1049 sshbuf_reset(e->request); 1050 send_status(e, 0); 1051 break; 1052 } 1053 return 1; 1054 } 1055 1056 static void 1057 new_socket(sock_type type, int fd) 1058 { 1059 u_int i, old_alloc, new_alloc; 1060 1061 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1062 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1063 set_nonblock(fd); 1064 1065 if (fd > max_fd) 1066 max_fd = fd; 1067 1068 for (i = 0; i < sockets_alloc; i++) 1069 if (sockets[i].type == AUTH_UNUSED) { 1070 sockets[i].fd = fd; 1071 if ((sockets[i].input = sshbuf_new()) == NULL || 1072 (sockets[i].output = sshbuf_new()) == NULL || 1073 (sockets[i].request = sshbuf_new()) == NULL) 1074 fatal_f("sshbuf_new failed"); 1075 sockets[i].type = type; 1076 return; 1077 } 1078 old_alloc = sockets_alloc; 1079 new_alloc = sockets_alloc + 10; 1080 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1081 sizeof(sockets[0])); 1082 for (i = old_alloc; i < new_alloc; i++) 1083 sockets[i].type = AUTH_UNUSED; 1084 sockets_alloc = new_alloc; 1085 sockets[old_alloc].fd = fd; 1086 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1087 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1088 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1089 fatal_f("sshbuf_new failed"); 1090 sockets[old_alloc].type = type; 1091 } 1092 1093 static int 1094 handle_socket_read(u_int socknum) 1095 { 1096 struct sockaddr_un sunaddr; 1097 socklen_t slen; 1098 uid_t euid; 1099 gid_t egid; 1100 int fd; 1101 1102 slen = sizeof(sunaddr); 1103 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1104 if (fd == -1) { 1105 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1106 return -1; 1107 } 1108 if (getpeereid(fd, &euid, &egid) == -1) { 1109 error("getpeereid %d failed: %s", fd, strerror(errno)); 1110 close(fd); 1111 return -1; 1112 } 1113 if ((euid != 0) && (getuid() != euid)) { 1114 error("uid mismatch: peer euid %u != uid %u", 1115 (u_int) euid, (u_int) getuid()); 1116 close(fd); 1117 return -1; 1118 } 1119 new_socket(AUTH_CONNECTION, fd); 1120 return 0; 1121 } 1122 1123 static int 1124 handle_conn_read(u_int socknum) 1125 { 1126 char buf[AGENT_RBUF_LEN]; 1127 ssize_t len; 1128 int r; 1129 1130 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1131 if (len == -1) { 1132 if (errno == EAGAIN || errno == EINTR) 1133 return 0; 1134 error_f("read error on socket %u (fd %d): %s", 1135 socknum, sockets[socknum].fd, strerror(errno)); 1136 } 1137 return -1; 1138 } 1139 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1140 fatal_fr(r, "compose"); 1141 explicit_bzero(buf, sizeof(buf)); 1142 for (;;) { 1143 if ((r = process_message(socknum)) == -1) 1144 return -1; 1145 else if (r == 0) 1146 break; 1147 } 1148 return 0; 1149 } 1150 1151 static int 1152 handle_conn_write(u_int socknum) 1153 { 1154 ssize_t len; 1155 int r; 1156 1157 if (sshbuf_len(sockets[socknum].output) == 0) 1158 return 0; /* shouldn't happen */ 1159 if ((len = write(sockets[socknum].fd, 1160 sshbuf_ptr(sockets[socknum].output), 1161 sshbuf_len(sockets[socknum].output))) <= 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_consume(sockets[socknum].output, len)) != 0) 1171 fatal_fr(r, "consume"); 1172 return 0; 1173 } 1174 1175 static void 1176 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1177 { 1178 size_t i; 1179 u_int socknum, activefds = npfd; 1180 1181 for (i = 0; i < npfd; i++) { 1182 if (pfd[i].revents == 0) 1183 continue; 1184 /* Find sockets entry */ 1185 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1186 if (sockets[socknum].type != AUTH_SOCKET && 1187 sockets[socknum].type != AUTH_CONNECTION) 1188 continue; 1189 if (pfd[i].fd == sockets[socknum].fd) 1190 break; 1191 } 1192 if (socknum >= sockets_alloc) { 1193 error_f("no socket for fd %d", pfd[i].fd); 1194 continue; 1195 } 1196 /* Process events */ 1197 switch (sockets[socknum].type) { 1198 case AUTH_SOCKET: 1199 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1200 break; 1201 if (npfd > maxfds) { 1202 debug3("out of fds (active %u >= limit %u); " 1203 "skipping accept", activefds, maxfds); 1204 break; 1205 } 1206 if (handle_socket_read(socknum) == 0) 1207 activefds++; 1208 break; 1209 case AUTH_CONNECTION: 1210 if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 && 1211 handle_conn_read(socknum) != 0) { 1212 goto close_sock; 1213 } 1214 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1215 handle_conn_write(socknum) != 0) { 1216 close_sock: 1217 if (activefds == 0) 1218 fatal("activefds == 0 at close_sock"); 1219 close_socket(&sockets[socknum]); 1220 activefds--; 1221 break; 1222 } 1223 break; 1224 default: 1225 break; 1226 } 1227 } 1228 } 1229 1230 static int 1231 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1232 { 1233 struct pollfd *pfd = *pfdp; 1234 size_t i, j, npfd = 0; 1235 time_t deadline; 1236 int r; 1237 1238 /* Count active sockets */ 1239 for (i = 0; i < sockets_alloc; i++) { 1240 switch (sockets[i].type) { 1241 case AUTH_SOCKET: 1242 case AUTH_CONNECTION: 1243 npfd++; 1244 break; 1245 case AUTH_UNUSED: 1246 break; 1247 default: 1248 fatal("Unknown socket type %d", sockets[i].type); 1249 break; 1250 } 1251 } 1252 if (npfd != *npfdp && 1253 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1254 fatal_f("recallocarray failed"); 1255 *pfdp = pfd; 1256 *npfdp = npfd; 1257 1258 for (i = j = 0; i < sockets_alloc; i++) { 1259 switch (sockets[i].type) { 1260 case AUTH_SOCKET: 1261 if (npfd > maxfds) { 1262 debug3("out of fds (active %zu >= limit %u); " 1263 "skipping arming listener", npfd, maxfds); 1264 break; 1265 } 1266 pfd[j].fd = sockets[i].fd; 1267 pfd[j].revents = 0; 1268 pfd[j].events = POLLIN; 1269 j++; 1270 break; 1271 case AUTH_CONNECTION: 1272 pfd[j].fd = sockets[i].fd; 1273 pfd[j].revents = 0; 1274 /* 1275 * Only prepare to read if we can handle a full-size 1276 * input read buffer and enqueue a max size reply.. 1277 */ 1278 if ((r = sshbuf_check_reserve(sockets[i].input, 1279 AGENT_RBUF_LEN)) == 0 && 1280 (r = sshbuf_check_reserve(sockets[i].output, 1281 AGENT_MAX_LEN)) == 0) 1282 pfd[j].events = POLLIN; 1283 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1284 fatal_fr(r, "reserve"); 1285 if (sshbuf_len(sockets[i].output) > 0) 1286 pfd[j].events |= POLLOUT; 1287 j++; 1288 break; 1289 default: 1290 break; 1291 } 1292 } 1293 deadline = reaper(); 1294 if (parent_alive_interval != 0) 1295 deadline = (deadline == 0) ? parent_alive_interval : 1296 MINIMUM(deadline, parent_alive_interval); 1297 if (deadline == 0) { 1298 *timeoutp = -1; /* INFTIM */ 1299 } else { 1300 if (deadline > INT_MAX / 1000) 1301 *timeoutp = INT_MAX / 1000; 1302 else 1303 *timeoutp = deadline * 1000; 1304 } 1305 return (1); 1306 } 1307 1308 static void 1309 cleanup_socket(void) 1310 { 1311 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1312 return; 1313 debug_f("cleanup"); 1314 if (socket_name[0]) 1315 unlink(socket_name); 1316 if (socket_dir[0]) 1317 rmdir(socket_dir); 1318 } 1319 1320 void 1321 cleanup_exit(int i) 1322 { 1323 cleanup_socket(); 1324 _exit(i); 1325 } 1326 1327 /*ARGSUSED*/ 1328 __dead static void 1329 cleanup_handler(int sig) 1330 { 1331 cleanup_socket(); 1332 #ifdef ENABLE_PKCS11 1333 pkcs11_terminate(); 1334 #endif 1335 _exit(2); 1336 } 1337 1338 static void 1339 check_parent_exists(void) 1340 { 1341 /* 1342 * If our parent has exited then getppid() will return (pid_t)1, 1343 * so testing for that should be safe. 1344 */ 1345 if (parent_pid != -1 && getppid() != parent_pid) { 1346 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1347 cleanup_socket(); 1348 _exit(2); 1349 } 1350 } 1351 1352 __dead static void 1353 usage(void) 1354 { 1355 fprintf(stderr, 1356 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1357 " [-P allowed_providers] [-t life]\n" 1358 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1359 " [-t life] command [arg ...]\n" 1360 " ssh-agent [-c | -s] -k\n"); 1361 exit(1); 1362 } 1363 1364 static void 1365 csh_setenv(const char *name, const char *value) 1366 { 1367 printf("setenv %s %s;\n", name, value); 1368 } 1369 1370 static void 1371 csh_unsetenv(const char *name) 1372 { 1373 printf("unsetenv %s;\n", name); 1374 } 1375 1376 static void 1377 sh_setenv(const char *name, const char *value) 1378 { 1379 printf("%s=%s; export %s;\n", name, value, name); 1380 } 1381 1382 static void 1383 sh_unsetenv(const char *name) 1384 { 1385 printf("unset %s;\n", name); 1386 } 1387 int 1388 main(int ac, char **av) 1389 { 1390 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1391 int sock, ch, result, saved_errno; 1392 char *shell, *pidstr, *agentsocket = NULL; 1393 struct rlimit rlim; 1394 void (*f_setenv)(const char *, const char *); 1395 void (*f_unsetenv)(const char *); 1396 extern int optind; 1397 extern char *optarg; 1398 pid_t pid; 1399 char pidstrbuf[1 + 3 * sizeof pid]; 1400 size_t len; 1401 mode_t prev_mask; 1402 int timeout = -1; /* INFTIM */ 1403 struct pollfd *pfd = NULL; 1404 size_t npfd = 0; 1405 u_int maxfds; 1406 1407 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1408 sanitise_stdfd(); 1409 1410 /* drop */ 1411 setegid(getgid()); 1412 setgid(getgid()); 1413 1414 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1415 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1416 1417 #ifdef WITH_OPENSSL 1418 OpenSSL_add_all_algorithms(); 1419 #endif 1420 1421 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 1422 switch (ch) { 1423 case 'E': 1424 fingerprint_hash = ssh_digest_alg_by_name(optarg); 1425 if (fingerprint_hash == -1) 1426 fatal("Invalid hash algorithm \"%s\"", optarg); 1427 break; 1428 case 'c': 1429 if (s_flag) 1430 usage(); 1431 c_flag++; 1432 break; 1433 case 'k': 1434 k_flag++; 1435 break; 1436 case 'O': 1437 if (strcmp(optarg, "no-restrict-websafe") == 0) 1438 restrict_websafe = 0; 1439 else 1440 fatal("Unknown -O option"); 1441 break; 1442 case 'P': 1443 if (allowed_providers != NULL) 1444 fatal("-P option already specified"); 1445 allowed_providers = xstrdup(optarg); 1446 break; 1447 case 's': 1448 if (c_flag) 1449 usage(); 1450 s_flag++; 1451 break; 1452 case 'd': 1453 if (d_flag || D_flag) 1454 usage(); 1455 d_flag++; 1456 break; 1457 case 'D': 1458 if (d_flag || D_flag) 1459 usage(); 1460 D_flag++; 1461 break; 1462 case 'a': 1463 agentsocket = optarg; 1464 break; 1465 case 't': 1466 if ((lifetime = convtime(optarg)) == -1) { 1467 fprintf(stderr, "Invalid lifetime\n"); 1468 usage(); 1469 } 1470 break; 1471 default: 1472 usage(); 1473 } 1474 } 1475 ac -= optind; 1476 av += optind; 1477 1478 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 1479 usage(); 1480 1481 if (allowed_providers == NULL) 1482 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 1483 1484 if (ac == 0 && !c_flag && !s_flag) { 1485 shell = getenv("SHELL"); 1486 if (shell != NULL && (len = strlen(shell)) > 2 && 1487 strncmp(shell + len - 3, "csh", 3) == 0) 1488 c_flag = 1; 1489 } 1490 if (c_flag) { 1491 f_setenv = csh_setenv; 1492 f_unsetenv = csh_unsetenv; 1493 } else { 1494 f_setenv = sh_setenv; 1495 f_unsetenv = sh_unsetenv; 1496 } 1497 if (k_flag) { 1498 const char *errstr = NULL; 1499 1500 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 1501 if (pidstr == NULL) { 1502 fprintf(stderr, "%s not set, cannot kill agent\n", 1503 SSH_AGENTPID_ENV_NAME); 1504 exit(1); 1505 } 1506 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 1507 if (errstr) { 1508 fprintf(stderr, 1509 "%s=\"%s\", which is not a good PID: %s\n", 1510 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 1511 exit(1); 1512 } 1513 if (kill(pid, SIGTERM) == -1) { 1514 perror("kill"); 1515 exit(1); 1516 } 1517 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 1518 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 1519 printf("echo Agent pid %ld killed;\n", (long)pid); 1520 exit(0); 1521 } 1522 1523 /* 1524 * Minimum file descriptors: 1525 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 1526 * a few spare for libc / stack protectors / sanitisers, etc. 1527 */ 1528 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 1529 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 1530 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 1531 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 1532 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 1533 1534 parent_pid = getpid(); 1535 1536 if (agentsocket == NULL) { 1537 /* Create private directory for agent socket */ 1538 mktemp_proto(socket_dir, sizeof(socket_dir)); 1539 if (mkdtemp(socket_dir) == NULL) { 1540 perror("mkdtemp: private socket dir"); 1541 exit(1); 1542 } 1543 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 1544 (long)parent_pid); 1545 } else { 1546 /* Try to use specified agent socket */ 1547 socket_dir[0] = '\0'; 1548 strlcpy(socket_name, agentsocket, sizeof socket_name); 1549 } 1550 1551 /* 1552 * Create socket early so it will exist before command gets run from 1553 * the parent. 1554 */ 1555 prev_mask = umask(0177); 1556 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 1557 if (sock < 0) { 1558 /* XXX - unix_listener() calls error() not perror() */ 1559 *socket_name = '\0'; /* Don't unlink any existing file */ 1560 cleanup_exit(1); 1561 } 1562 umask(prev_mask); 1563 1564 /* 1565 * Fork, and have the parent execute the command, if any, or present 1566 * the socket data. The child continues as the authentication agent. 1567 */ 1568 if (D_flag || d_flag) { 1569 log_init(__progname, 1570 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 1571 SYSLOG_FACILITY_AUTH, 1); 1572 if (c_flag) 1573 printf("setenv %s %s;\n", 1574 SSH_AUTHSOCKET_ENV_NAME, socket_name); 1575 else 1576 printf("%s=%s; export %s;\n", 1577 SSH_AUTHSOCKET_ENV_NAME, socket_name, 1578 SSH_AUTHSOCKET_ENV_NAME); 1579 printf("echo Agent pid %ld;\n", (long)parent_pid); 1580 fflush(stdout); 1581 goto skip; 1582 } 1583 pid = fork(); 1584 if (pid == -1) { 1585 perror("fork"); 1586 cleanup_exit(1); 1587 } 1588 if (pid != 0) { /* Parent - execute the given command. */ 1589 close(sock); 1590 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 1591 if (ac == 0) { 1592 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 1593 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 1594 printf("echo Agent pid %ld;\n", (long)pid); 1595 exit(0); 1596 } 1597 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 1598 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 1599 perror("setenv"); 1600 exit(1); 1601 } 1602 execvp(av[0], av); 1603 perror(av[0]); 1604 exit(1); 1605 } 1606 /* child */ 1607 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 1608 1609 if (setsid() == -1) { 1610 error("setsid: %s", strerror(errno)); 1611 cleanup_exit(1); 1612 } 1613 1614 (void)chdir("/"); 1615 if (stdfd_devnull(1, 1, 1) == -1) 1616 error_f("stdfd_devnull failed"); 1617 1618 /* deny core dumps, since memory contains unencrypted private keys */ 1619 rlim.rlim_cur = rlim.rlim_max = 0; 1620 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 1621 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 1622 cleanup_exit(1); 1623 } 1624 1625 skip: 1626 1627 cleanup_pid = getpid(); 1628 1629 #ifdef ENABLE_PKCS11 1630 pkcs11_init(0); 1631 #endif 1632 new_socket(AUTH_SOCKET, sock); 1633 if (ac > 0) 1634 parent_alive_interval = 10; 1635 idtab_init(); 1636 ssh_signal(SIGPIPE, SIG_IGN); 1637 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 1638 ssh_signal(SIGHUP, cleanup_handler); 1639 ssh_signal(SIGTERM, cleanup_handler); 1640 1641 #ifdef __OpenBSD__ 1642 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 1643 fatal("%s: pledge: %s", __progname, strerror(errno)); 1644 #endif 1645 1646 while (1) { 1647 prepare_poll(&pfd, &npfd, &timeout, maxfds); 1648 result = poll(pfd, npfd, timeout); 1649 saved_errno = errno; 1650 if (parent_alive_interval != 0) 1651 check_parent_exists(); 1652 (void) reaper(); /* remove expired keys */ 1653 if (result == -1) { 1654 if (saved_errno == EINTR) 1655 continue; 1656 fatal("poll: %s", strerror(saved_errno)); 1657 } else if (result > 0) 1658 after_poll(pfd, npfd, maxfds); 1659 } 1660 /* NOTREACHED */ 1661 } 1662