1 /* $OpenBSD: ssh-agent.c,v 1.294 2022/12/04 11:03:11 dtucker 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 "pathnames.h" 78 #include "ssh-pkcs11.h" 79 #include "sk-api.h" 80 #include "myproposal.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 /* Maximum number of recorded session IDs/hostkeys per connection */ 91 #define AGENT_MAX_SESSION_IDS 16 92 /* Maximum size of session ID */ 93 #define AGENT_MAX_SID_LEN 128 94 /* Maximum number of destination constraints to accept on a key */ 95 #define AGENT_MAX_DEST_CONSTRAINTS 1024 96 97 /* XXX store hostkey_sid in a refcounted tree */ 98 99 typedef enum { 100 AUTH_UNUSED = 0, 101 AUTH_SOCKET = 1, 102 AUTH_CONNECTION = 2, 103 } sock_type; 104 105 struct hostkey_sid { 106 struct sshkey *key; 107 struct sshbuf *sid; 108 int forwarded; 109 }; 110 111 typedef struct socket_entry { 112 int fd; 113 sock_type type; 114 struct sshbuf *input; 115 struct sshbuf *output; 116 struct sshbuf *request; 117 size_t nsession_ids; 118 struct hostkey_sid *session_ids; 119 } SocketEntry; 120 121 u_int sockets_alloc = 0; 122 SocketEntry *sockets = NULL; 123 124 typedef struct identity { 125 TAILQ_ENTRY(identity) next; 126 struct sshkey *key; 127 char *comment; 128 char *provider; 129 time_t death; 130 u_int confirm; 131 char *sk_provider; 132 struct dest_constraint *dest_constraints; 133 size_t ndest_constraints; 134 } Identity; 135 136 struct idtable { 137 int nentries; 138 TAILQ_HEAD(idqueue, identity) idlist; 139 }; 140 141 /* private key table */ 142 struct idtable *idtab; 143 144 int max_fd = 0; 145 146 /* pid of shell == parent of agent */ 147 pid_t parent_pid = -1; 148 time_t parent_alive_interval = 0; 149 150 /* pid of process for which cleanup_socket is applicable */ 151 pid_t cleanup_pid = 0; 152 153 /* pathname and directory for AUTH_SOCKET */ 154 char socket_name[PATH_MAX]; 155 char socket_dir[PATH_MAX]; 156 157 /* Pattern-list of allowed PKCS#11/Security key paths */ 158 static char *allowed_providers; 159 160 /* locking */ 161 #define LOCK_SIZE 32 162 #define LOCK_SALT_SIZE 16 163 #define LOCK_ROUNDS 1 164 int locked = 0; 165 u_char lock_pwhash[LOCK_SIZE]; 166 u_char lock_salt[LOCK_SALT_SIZE]; 167 168 extern char *__progname; 169 170 /* Default lifetime in seconds (0 == forever) */ 171 static int lifetime = 0; 172 173 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 174 175 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 176 static int restrict_websafe = 1; 177 178 static void 179 close_socket(SocketEntry *e) 180 { 181 size_t i; 182 183 close(e->fd); 184 sshbuf_free(e->input); 185 sshbuf_free(e->output); 186 sshbuf_free(e->request); 187 for (i = 0; i < e->nsession_ids; i++) { 188 sshkey_free(e->session_ids[i].key); 189 sshbuf_free(e->session_ids[i].sid); 190 } 191 free(e->session_ids); 192 memset(e, '\0', sizeof(*e)); 193 e->fd = -1; 194 e->type = AUTH_UNUSED; 195 } 196 197 static void 198 idtab_init(void) 199 { 200 idtab = xcalloc(1, sizeof(*idtab)); 201 TAILQ_INIT(&idtab->idlist); 202 idtab->nentries = 0; 203 } 204 205 static void 206 free_dest_constraint_hop(struct dest_constraint_hop *dch) 207 { 208 u_int i; 209 210 if (dch == NULL) 211 return; 212 free(dch->user); 213 free(dch->hostname); 214 for (i = 0; i < dch->nkeys; i++) 215 sshkey_free(dch->keys[i]); 216 free(dch->keys); 217 free(dch->key_is_ca); 218 } 219 220 static void 221 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 222 { 223 size_t i; 224 225 for (i = 0; i < ndcs; i++) { 226 free_dest_constraint_hop(&dcs[i].from); 227 free_dest_constraint_hop(&dcs[i].to); 228 } 229 free(dcs); 230 } 231 232 static void 233 free_identity(Identity *id) 234 { 235 sshkey_free(id->key); 236 free(id->provider); 237 free(id->comment); 238 free(id->sk_provider); 239 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 240 free(id); 241 } 242 243 /* 244 * Match 'key' against the key/CA list in a destination constraint hop 245 * Returns 0 on success or -1 otherwise. 246 */ 247 static int 248 match_key_hop(const char *tag, const struct sshkey *key, 249 const struct dest_constraint_hop *dch) 250 { 251 const char *reason = NULL; 252 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 253 u_int i; 254 char *fp; 255 256 if (key == NULL) 257 return -1; 258 /* XXX logspam */ 259 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 260 SSH_FP_DEFAULT)) == NULL) 261 fatal_f("fingerprint failed"); 262 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 263 tag, hostname, sshkey_type(key), fp, dch->nkeys); 264 free(fp); 265 for (i = 0; i < dch->nkeys; i++) { 266 if (dch->keys[i] == NULL) 267 return -1; 268 /* XXX logspam */ 269 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 270 SSH_FP_DEFAULT)) == NULL) 271 fatal_f("fingerprint failed"); 272 debug3_f("%s: key %u: %s%s %s", tag, i, 273 dch->key_is_ca[i] ? "CA " : "", 274 sshkey_type(dch->keys[i]), fp); 275 free(fp); 276 if (!sshkey_is_cert(key)) { 277 /* plain key */ 278 if (dch->key_is_ca[i] || 279 !sshkey_equal(key, dch->keys[i])) 280 continue; 281 return 0; 282 } 283 /* certificate */ 284 if (!dch->key_is_ca[i]) 285 continue; 286 if (key->cert == NULL || key->cert->signature_key == NULL) 287 return -1; /* shouldn't happen */ 288 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 289 continue; 290 if (sshkey_cert_check_host(key, hostname, 1, 291 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 292 debug_f("cert %s / hostname %s rejected: %s", 293 key->cert->key_id, hostname, reason); 294 continue; 295 } 296 return 0; 297 } 298 return -1; 299 } 300 301 /* Check destination constraints on an identity against the hostkey/user */ 302 static int 303 permitted_by_dest_constraints(const struct sshkey *fromkey, 304 const struct sshkey *tokey, Identity *id, const char *user, 305 const char **hostnamep) 306 { 307 size_t i; 308 struct dest_constraint *d; 309 310 if (hostnamep != NULL) 311 *hostnamep = NULL; 312 for (i = 0; i < id->ndest_constraints; i++) { 313 d = id->dest_constraints + i; 314 /* XXX remove logspam */ 315 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 316 i, d->from.user ? d->from.user : "", 317 d->from.user ? "@" : "", 318 d->from.hostname ? d->from.hostname : "(ORIGIN)", 319 d->from.nkeys, 320 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 321 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 322 323 /* Match 'from' key */ 324 if (fromkey == NULL) { 325 /* We are matching the first hop */ 326 if (d->from.hostname != NULL || d->from.nkeys != 0) 327 continue; 328 } else if (match_key_hop("from", fromkey, &d->from) != 0) 329 continue; 330 331 /* Match 'to' key */ 332 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 333 continue; 334 335 /* Match user if specified */ 336 if (d->to.user != NULL && user != NULL && 337 !match_pattern(user, d->to.user)) 338 continue; 339 340 /* successfully matched this constraint */ 341 if (hostnamep != NULL) 342 *hostnamep = d->to.hostname; 343 debug2_f("allowed for hostname %s", 344 d->to.hostname == NULL ? "*" : d->to.hostname); 345 return 0; 346 } 347 /* no match */ 348 debug2_f("%s identity \"%s\" not permitted for this destination", 349 sshkey_type(id->key), id->comment); 350 return -1; 351 } 352 353 /* 354 * Check whether hostkeys on a SocketEntry and the optionally specified user 355 * are permitted by the destination constraints on the Identity. 356 * Returns 0 on success or -1 otherwise. 357 */ 358 static int 359 identity_permitted(Identity *id, SocketEntry *e, char *user, 360 const char **forward_hostnamep, const char **last_hostnamep) 361 { 362 size_t i; 363 const char **hp; 364 struct hostkey_sid *hks; 365 const struct sshkey *fromkey = NULL; 366 const char *test_user; 367 char *fp1, *fp2; 368 369 /* XXX remove logspam */ 370 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 371 "%zu constraints", sshkey_type(id->key), id->comment, 372 e->nsession_ids, id->ndest_constraints); 373 if (id->ndest_constraints == 0) 374 return 0; /* unconstrained */ 375 if (e->nsession_ids == 0) 376 return 0; /* local use */ 377 /* 378 * Walk through the hops recorded by session_id and try to find a 379 * constraint that satisfies each. 380 */ 381 for (i = 0; i < e->nsession_ids; i++) { 382 hks = e->session_ids + i; 383 if (hks->key == NULL) 384 fatal_f("internal error: no bound key"); 385 /* XXX remove logspam */ 386 fp1 = fp2 = NULL; 387 if (fromkey != NULL && 388 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 389 SSH_FP_DEFAULT)) == NULL) 390 fatal_f("fingerprint failed"); 391 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 392 SSH_FP_DEFAULT)) == NULL) 393 fatal_f("fingerprint failed"); 394 debug3_f("socketentry fd=%d, entry %zu %s, " 395 "from hostkey %s %s to user %s hostkey %s %s", 396 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 397 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 398 fromkey ? fp1 : "", user ? user : "(ANY)", 399 sshkey_type(hks->key), fp2); 400 free(fp1); 401 free(fp2); 402 /* 403 * Record the hostnames for the initial forwarding and 404 * the final destination. 405 */ 406 hp = NULL; 407 if (i == e->nsession_ids - 1) 408 hp = last_hostnamep; 409 else if (i == 0) 410 hp = forward_hostnamep; 411 /* Special handling for final recorded binding */ 412 test_user = NULL; 413 if (i == e->nsession_ids - 1) { 414 /* Can only check user at final hop */ 415 test_user = user; 416 /* 417 * user is only presented for signature requests. 418 * If this is the case, make sure last binding is not 419 * for a forwarding. 420 */ 421 if (hks->forwarded && user != NULL) { 422 error_f("tried to sign on forwarding hop"); 423 return -1; 424 } 425 } else if (!hks->forwarded) { 426 error_f("tried to forward though signing bind"); 427 return -1; 428 } 429 if (permitted_by_dest_constraints(fromkey, hks->key, id, 430 test_user, hp) != 0) 431 return -1; 432 fromkey = hks->key; 433 } 434 /* 435 * Another special case: if the last bound session ID was for a 436 * forwarding, and this function is not being called to check a sign 437 * request (i.e. no 'user' supplied), then only permit the key if 438 * there is a permission that would allow it to be used at another 439 * destination. This hides keys that are allowed to be used to 440 * authenticate *to* a host but not permitted for *use* beyond it. 441 */ 442 hks = &e->session_ids[e->nsession_ids - 1]; 443 if (hks->forwarded && user == NULL && 444 permitted_by_dest_constraints(hks->key, NULL, id, 445 NULL, NULL) != 0) { 446 debug3_f("key permitted at host but not after"); 447 return -1; 448 } 449 450 /* success */ 451 return 0; 452 } 453 454 /* return matching private key for given public key */ 455 static Identity * 456 lookup_identity(struct sshkey *key) 457 { 458 Identity *id; 459 460 TAILQ_FOREACH(id, &idtab->idlist, next) { 461 if (sshkey_equal(key, id->key)) 462 return (id); 463 } 464 return (NULL); 465 } 466 467 /* Check confirmation of keysign request */ 468 static int 469 confirm_key(Identity *id, const char *extra) 470 { 471 char *p; 472 int ret = -1; 473 474 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 475 if (p != NULL && 476 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 477 id->comment, p, 478 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 479 ret = 0; 480 free(p); 481 482 return (ret); 483 } 484 485 static void 486 send_status(SocketEntry *e, int success) 487 { 488 int r; 489 490 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 491 (r = sshbuf_put_u8(e->output, success ? 492 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 493 fatal_fr(r, "compose"); 494 } 495 496 /* send list of supported public keys to 'client' */ 497 static void 498 process_request_identities(SocketEntry *e) 499 { 500 Identity *id; 501 struct sshbuf *msg, *keys; 502 int r; 503 u_int nentries = 0; 504 505 debug2_f("entering"); 506 507 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 508 fatal_f("sshbuf_new failed"); 509 TAILQ_FOREACH(id, &idtab->idlist, next) { 510 /* identity not visible, don't include in response */ 511 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 512 continue; 513 if ((r = sshkey_puts_opts(id->key, keys, 514 SSHKEY_SERIALIZE_INFO)) != 0 || 515 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 516 error_fr(r, "compose key/comment"); 517 continue; 518 } 519 nentries++; 520 } 521 debug2_f("replying with %u allowed of %u available keys", 522 nentries, idtab->nentries); 523 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 524 (r = sshbuf_put_u32(msg, nentries)) != 0 || 525 (r = sshbuf_putb(msg, keys)) != 0) 526 fatal_fr(r, "compose"); 527 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 528 fatal_fr(r, "enqueue"); 529 sshbuf_free(msg); 530 sshbuf_free(keys); 531 } 532 533 534 static char * 535 agent_decode_alg(struct sshkey *key, u_int flags) 536 { 537 if (key->type == KEY_RSA) { 538 if (flags & SSH_AGENT_RSA_SHA2_256) 539 return "rsa-sha2-256"; 540 else if (flags & SSH_AGENT_RSA_SHA2_512) 541 return "rsa-sha2-512"; 542 } else if (key->type == KEY_RSA_CERT) { 543 if (flags & SSH_AGENT_RSA_SHA2_256) 544 return "rsa-sha2-256-cert-v01@openssh.com"; 545 else if (flags & SSH_AGENT_RSA_SHA2_512) 546 return "rsa-sha2-512-cert-v01@openssh.com"; 547 } 548 return NULL; 549 } 550 551 /* 552 * Attempt to parse the contents of a buffer as a SSH publickey userauth 553 * request, checking its contents for consistency and matching the embedded 554 * key against the one that is being used for signing. 555 * Note: does not modify msg buffer. 556 * Optionally extract the username, session ID and/or hostkey from the request. 557 */ 558 static int 559 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 560 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 561 { 562 struct sshbuf *b = NULL, *sess_id = NULL; 563 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 564 int r; 565 u_char t, sig_follows; 566 struct sshkey *mkey = NULL, *hostkey = NULL; 567 568 if (userp != NULL) 569 *userp = NULL; 570 if (sess_idp != NULL) 571 *sess_idp = NULL; 572 if (hostkeyp != NULL) 573 *hostkeyp = NULL; 574 if ((b = sshbuf_fromb(msg)) == NULL) 575 fatal_f("sshbuf_fromb"); 576 577 /* SSH userauth request */ 578 if ((r = sshbuf_froms(b, &sess_id)) != 0) 579 goto out; 580 if (sshbuf_len(sess_id) == 0) { 581 r = SSH_ERR_INVALID_FORMAT; 582 goto out; 583 } 584 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 585 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 586 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 587 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 588 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 589 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 590 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 591 goto out; 592 if (t != SSH2_MSG_USERAUTH_REQUEST || 593 sig_follows != 1 || 594 strcmp(service, "ssh-connection") != 0 || 595 !sshkey_equal(expected_key, mkey) || 596 sshkey_type_from_name(pkalg) != expected_key->type) { 597 r = SSH_ERR_INVALID_FORMAT; 598 goto out; 599 } 600 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 601 if ((r = sshkey_froms(b, &hostkey)) != 0) 602 goto out; 603 } else if (strcmp(method, "publickey") != 0) { 604 r = SSH_ERR_INVALID_FORMAT; 605 goto out; 606 } 607 if (sshbuf_len(b) != 0) { 608 r = SSH_ERR_INVALID_FORMAT; 609 goto out; 610 } 611 /* success */ 612 r = 0; 613 debug3_f("well formed userauth"); 614 if (userp != NULL) { 615 *userp = user; 616 user = NULL; 617 } 618 if (sess_idp != NULL) { 619 *sess_idp = sess_id; 620 sess_id = NULL; 621 } 622 if (hostkeyp != NULL) { 623 *hostkeyp = hostkey; 624 hostkey = NULL; 625 } 626 out: 627 sshbuf_free(b); 628 sshbuf_free(sess_id); 629 free(user); 630 free(service); 631 free(method); 632 free(pkalg); 633 sshkey_free(mkey); 634 sshkey_free(hostkey); 635 return r; 636 } 637 638 /* 639 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 640 * Note: does not modify buffer. 641 */ 642 static int 643 parse_sshsig_request(struct sshbuf *msg) 644 { 645 int r; 646 struct sshbuf *b; 647 648 if ((b = sshbuf_fromb(msg)) == NULL) 649 fatal_f("sshbuf_fromb"); 650 651 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 652 (r = sshbuf_consume(b, 6)) != 0 || 653 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 654 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 655 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 656 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 657 goto out; 658 if (sshbuf_len(b) != 0) { 659 r = SSH_ERR_INVALID_FORMAT; 660 goto out; 661 } 662 /* success */ 663 r = 0; 664 out: 665 sshbuf_free(b); 666 return r; 667 } 668 669 /* 670 * This function inspects a message to be signed by a FIDO key that has a 671 * web-like application string (i.e. one that does not begin with "ssh:". 672 * It checks that the message is one of those expected for SSH operations 673 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 674 * for the web. 675 */ 676 static int 677 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 678 { 679 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 680 debug_f("signed data matches public key userauth request"); 681 return 1; 682 } 683 if (parse_sshsig_request(data) == 0) { 684 debug_f("signed data matches SSHSIG signature request"); 685 return 1; 686 } 687 688 /* XXX check CA signature operation */ 689 690 error("web-origin key attempting to sign non-SSH message"); 691 return 0; 692 } 693 694 static int 695 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 696 { 697 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 698 return SSH_ERR_INVALID_ARGUMENT; 699 if (sshbuf_len(a) != sshbuf_len(b)) 700 return SSH_ERR_INVALID_FORMAT; 701 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 702 return SSH_ERR_INVALID_FORMAT; 703 return 0; 704 } 705 706 /* ssh2 only */ 707 static void 708 process_sign_request2(SocketEntry *e) 709 { 710 u_char *signature = NULL; 711 size_t slen = 0; 712 u_int compat = 0, flags; 713 int r, ok = -1, retried = 0; 714 char *fp = NULL, *pin = NULL, *prompt = NULL; 715 char *user = NULL, *sig_dest = NULL; 716 const char *fwd_host = NULL, *dest_host = NULL; 717 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 718 struct sshkey *key = NULL, *hostkey = NULL; 719 struct identity *id; 720 struct notifier_ctx *notifier = NULL; 721 722 debug_f("entering"); 723 724 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 725 fatal_f("sshbuf_new failed"); 726 if ((r = sshkey_froms(e->request, &key)) != 0 || 727 (r = sshbuf_get_stringb(e->request, data)) != 0 || 728 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 729 error_fr(r, "parse"); 730 goto send; 731 } 732 733 if ((id = lookup_identity(key)) == NULL) { 734 verbose_f("%s key not found", sshkey_type(key)); 735 goto send; 736 } 737 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 738 SSH_FP_DEFAULT)) == NULL) 739 fatal_f("fingerprint failed"); 740 741 if (id->ndest_constraints != 0) { 742 if (e->nsession_ids == 0) { 743 logit_f("refusing use of destination-constrained key " 744 "to sign on unbound connection"); 745 goto send; 746 } 747 if (parse_userauth_request(data, key, &user, &sid, 748 &hostkey) != 0) { 749 logit_f("refusing use of destination-constrained key " 750 "to sign an unidentified signature"); 751 goto send; 752 } 753 /* XXX logspam */ 754 debug_f("user=%s", user); 755 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 756 goto send; 757 /* XXX display fwd_host/dest_host in askpass UI */ 758 /* 759 * Ensure that the session ID is the most recent one 760 * registered on the socket - it should have been bound by 761 * ssh immediately before userauth. 762 */ 763 if (buf_equal(sid, 764 e->session_ids[e->nsession_ids - 1].sid) != 0) { 765 error_f("unexpected session ID (%zu listed) on " 766 "signature request for target user %s with " 767 "key %s %s", e->nsession_ids, user, 768 sshkey_type(id->key), fp); 769 goto send; 770 } 771 /* 772 * Ensure that the hostkey embedded in the signature matches 773 * the one most recently bound to the socket. An exception is 774 * made for the initial forwarding hop. 775 */ 776 if (e->nsession_ids > 1 && hostkey == NULL) { 777 error_f("refusing use of destination-constrained key: " 778 "no hostkey recorded in signature for forwarded " 779 "connection"); 780 goto send; 781 } 782 if (hostkey != NULL && !sshkey_equal(hostkey, 783 e->session_ids[e->nsession_ids - 1].key)) { 784 error_f("refusing use of destination-constrained key: " 785 "mismatch between hostkey in request and most " 786 "recently bound session"); 787 goto send; 788 } 789 xasprintf(&sig_dest, "public key authentication request for " 790 "user \"%s\" to listed host", user); 791 } 792 if (id->confirm && confirm_key(id, sig_dest) != 0) { 793 verbose_f("user refused key"); 794 goto send; 795 } 796 if (sshkey_is_sk(id->key)) { 797 if (restrict_websafe && 798 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 799 !check_websafe_message_contents(key, data)) { 800 /* error already logged */ 801 goto send; 802 } 803 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 804 notifier = notify_start(0, 805 "Confirm user presence for key %s %s%s%s", 806 sshkey_type(id->key), fp, 807 sig_dest == NULL ? "" : "\n", 808 sig_dest == NULL ? "" : sig_dest); 809 } 810 } 811 retry_pin: 812 if ((r = sshkey_sign(id->key, &signature, &slen, 813 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 814 id->sk_provider, pin, compat)) != 0) { 815 debug_fr(r, "sshkey_sign"); 816 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 817 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 818 notify_complete(notifier, NULL); 819 notifier = NULL; 820 /* XXX include sig_dest */ 821 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 822 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 823 " and confirm user presence " : " ", 824 sshkey_type(id->key), fp); 825 pin = read_passphrase(prompt, RP_USE_ASKPASS); 826 retried = 1; 827 goto retry_pin; 828 } 829 error_fr(r, "sshkey_sign"); 830 goto send; 831 } 832 /* Success */ 833 ok = 0; 834 send: 835 debug_f("good signature"); 836 notify_complete(notifier, "User presence confirmed"); 837 838 if (ok == 0) { 839 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 840 (r = sshbuf_put_string(msg, signature, slen)) != 0) 841 fatal_fr(r, "compose"); 842 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 843 fatal_fr(r, "compose failure"); 844 845 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 846 fatal_fr(r, "enqueue"); 847 848 sshbuf_free(sid); 849 sshbuf_free(data); 850 sshbuf_free(msg); 851 sshkey_free(key); 852 sshkey_free(hostkey); 853 free(fp); 854 free(signature); 855 free(sig_dest); 856 free(user); 857 free(prompt); 858 if (pin != NULL) 859 freezero(pin, strlen(pin)); 860 } 861 862 /* shared */ 863 static void 864 process_remove_identity(SocketEntry *e) 865 { 866 int r, success = 0; 867 struct sshkey *key = NULL; 868 Identity *id; 869 870 debug2_f("entering"); 871 if ((r = sshkey_froms(e->request, &key)) != 0) { 872 error_fr(r, "parse key"); 873 goto done; 874 } 875 if ((id = lookup_identity(key)) == NULL) { 876 debug_f("key not found"); 877 goto done; 878 } 879 /* identity not visible, cannot be removed */ 880 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 881 goto done; /* error already logged */ 882 /* We have this key, free it. */ 883 if (idtab->nentries < 1) 884 fatal_f("internal error: nentries %d", idtab->nentries); 885 TAILQ_REMOVE(&idtab->idlist, id, next); 886 free_identity(id); 887 idtab->nentries--; 888 success = 1; 889 done: 890 sshkey_free(key); 891 send_status(e, success); 892 } 893 894 static void 895 process_remove_all_identities(SocketEntry *e) 896 { 897 Identity *id; 898 899 debug2_f("entering"); 900 /* Loop over all identities and clear the keys. */ 901 for (id = TAILQ_FIRST(&idtab->idlist); id; 902 id = TAILQ_FIRST(&idtab->idlist)) { 903 TAILQ_REMOVE(&idtab->idlist, id, next); 904 free_identity(id); 905 } 906 907 /* Mark that there are no identities. */ 908 idtab->nentries = 0; 909 910 /* Send success. */ 911 send_status(e, 1); 912 } 913 914 /* removes expired keys and returns number of seconds until the next expiry */ 915 static time_t 916 reaper(void) 917 { 918 time_t deadline = 0, now = monotime(); 919 Identity *id, *nxt; 920 921 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 922 nxt = TAILQ_NEXT(id, next); 923 if (id->death == 0) 924 continue; 925 if (now >= id->death) { 926 debug("expiring key '%s'", id->comment); 927 TAILQ_REMOVE(&idtab->idlist, id, next); 928 free_identity(id); 929 idtab->nentries--; 930 } else 931 deadline = (deadline == 0) ? id->death : 932 MINIMUM(deadline, id->death); 933 } 934 if (deadline == 0 || deadline <= now) 935 return 0; 936 else 937 return (deadline - now); 938 } 939 940 static int 941 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 942 { 943 u_char key_is_ca; 944 size_t elen = 0; 945 int r; 946 struct sshkey *k = NULL; 947 char *fp; 948 949 memset(dch, '\0', sizeof(*dch)); 950 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 951 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 952 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 953 error_fr(r, "parse"); 954 goto out; 955 } 956 if (elen != 0) { 957 error_f("unsupported extensions (len %zu)", elen); 958 r = SSH_ERR_FEATURE_UNSUPPORTED; 959 goto out; 960 } 961 if (*dch->hostname == '\0') { 962 free(dch->hostname); 963 dch->hostname = NULL; 964 } 965 if (*dch->user == '\0') { 966 free(dch->user); 967 dch->user = NULL; 968 } 969 while (sshbuf_len(b) != 0) { 970 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 971 dch->nkeys + 1, sizeof(*dch->keys)); 972 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 973 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 974 if ((r = sshkey_froms(b, &k)) != 0 || 975 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 976 goto out; 977 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 978 SSH_FP_DEFAULT)) == NULL) 979 fatal_f("fingerprint failed"); 980 debug3_f("%s%s%s: adding %skey %s %s", 981 dch->user == NULL ? "" : dch->user, 982 dch->user == NULL ? "" : "@", 983 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 984 free(fp); 985 dch->keys[dch->nkeys] = k; 986 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 987 dch->nkeys++; 988 k = NULL; /* transferred */ 989 } 990 /* success */ 991 r = 0; 992 out: 993 sshkey_free(k); 994 return r; 995 } 996 997 static int 998 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 999 { 1000 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1001 int r; 1002 size_t elen = 0; 1003 1004 debug3_f("entering"); 1005 1006 memset(dc, '\0', sizeof(*dc)); 1007 if ((r = sshbuf_froms(m, &b)) != 0 || 1008 (r = sshbuf_froms(b, &frombuf)) != 0 || 1009 (r = sshbuf_froms(b, &tobuf)) != 0 || 1010 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1011 error_fr(r, "parse"); 1012 goto out; 1013 } 1014 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1015 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1016 goto out; /* already logged */ 1017 if (elen != 0) { 1018 error_f("unsupported extensions (len %zu)", elen); 1019 r = SSH_ERR_FEATURE_UNSUPPORTED; 1020 goto out; 1021 } 1022 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1023 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1024 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1025 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1026 /* check consistency */ 1027 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1028 dc->from.user != NULL) { 1029 error_f("inconsistent \"from\" specification"); 1030 r = SSH_ERR_INVALID_FORMAT; 1031 goto out; 1032 } 1033 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1034 error_f("incomplete \"to\" specification"); 1035 r = SSH_ERR_INVALID_FORMAT; 1036 goto out; 1037 } 1038 /* success */ 1039 r = 0; 1040 out: 1041 sshbuf_free(b); 1042 sshbuf_free(frombuf); 1043 sshbuf_free(tobuf); 1044 return r; 1045 } 1046 1047 static int 1048 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1049 struct dest_constraint **dcsp, size_t *ndcsp) 1050 { 1051 char *ext_name = NULL; 1052 int r; 1053 struct sshbuf *b = NULL; 1054 1055 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1056 error_fr(r, "parse constraint extension"); 1057 goto out; 1058 } 1059 debug_f("constraint ext %s", ext_name); 1060 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1061 if (sk_providerp == NULL) { 1062 error_f("%s not valid here", ext_name); 1063 r = SSH_ERR_INVALID_FORMAT; 1064 goto out; 1065 } 1066 if (*sk_providerp != NULL) { 1067 error_f("%s already set", ext_name); 1068 r = SSH_ERR_INVALID_FORMAT; 1069 goto out; 1070 } 1071 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1072 error_fr(r, "parse %s", ext_name); 1073 goto out; 1074 } 1075 } else if (strcmp(ext_name, 1076 "restrict-destination-v00@openssh.com") == 0) { 1077 if (*dcsp != NULL) { 1078 error_f("%s already set", ext_name); 1079 goto out; 1080 } 1081 if ((r = sshbuf_froms(m, &b)) != 0) { 1082 error_fr(r, "parse %s outer", ext_name); 1083 goto out; 1084 } 1085 while (sshbuf_len(b) != 0) { 1086 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1087 error_f("too many %s constraints", ext_name); 1088 goto out; 1089 } 1090 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1091 sizeof(**dcsp)); 1092 if ((r = parse_dest_constraint(b, 1093 *dcsp + (*ndcsp)++)) != 0) 1094 goto out; /* error already logged */ 1095 } 1096 } else { 1097 error_f("unsupported constraint \"%s\"", ext_name); 1098 r = SSH_ERR_FEATURE_UNSUPPORTED; 1099 goto out; 1100 } 1101 /* success */ 1102 r = 0; 1103 out: 1104 free(ext_name); 1105 sshbuf_free(b); 1106 return r; 1107 } 1108 1109 static int 1110 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1111 u_int *secondsp, int *confirmp, char **sk_providerp, 1112 struct dest_constraint **dcsp, size_t *ndcsp) 1113 { 1114 u_char ctype; 1115 int r; 1116 u_int seconds, maxsign = 0; 1117 1118 while (sshbuf_len(m)) { 1119 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1120 error_fr(r, "parse constraint type"); 1121 goto out; 1122 } 1123 switch (ctype) { 1124 case SSH_AGENT_CONSTRAIN_LIFETIME: 1125 if (*deathp != 0) { 1126 error_f("lifetime already set"); 1127 r = SSH_ERR_INVALID_FORMAT; 1128 goto out; 1129 } 1130 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1131 error_fr(r, "parse lifetime constraint"); 1132 goto out; 1133 } 1134 *deathp = monotime() + seconds; 1135 *secondsp = seconds; 1136 break; 1137 case SSH_AGENT_CONSTRAIN_CONFIRM: 1138 if (*confirmp != 0) { 1139 error_f("confirm already set"); 1140 r = SSH_ERR_INVALID_FORMAT; 1141 goto out; 1142 } 1143 *confirmp = 1; 1144 break; 1145 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1146 if (k == NULL) { 1147 error_f("maxsign not valid here"); 1148 r = SSH_ERR_INVALID_FORMAT; 1149 goto out; 1150 } 1151 if (maxsign != 0) { 1152 error_f("maxsign already set"); 1153 r = SSH_ERR_INVALID_FORMAT; 1154 goto out; 1155 } 1156 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1157 error_fr(r, "parse maxsign constraint"); 1158 goto out; 1159 } 1160 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1161 error_fr(r, "enable maxsign"); 1162 goto out; 1163 } 1164 break; 1165 case SSH_AGENT_CONSTRAIN_EXTENSION: 1166 if ((r = parse_key_constraint_extension(m, 1167 sk_providerp, dcsp, ndcsp)) != 0) 1168 goto out; /* error already logged */ 1169 break; 1170 default: 1171 error_f("Unknown constraint %d", ctype); 1172 r = SSH_ERR_FEATURE_UNSUPPORTED; 1173 goto out; 1174 } 1175 } 1176 /* success */ 1177 r = 0; 1178 out: 1179 return r; 1180 } 1181 1182 static void 1183 process_add_identity(SocketEntry *e) 1184 { 1185 Identity *id; 1186 int success = 0, confirm = 0; 1187 char *fp, *comment = NULL, *sk_provider = NULL; 1188 char canonical_provider[PATH_MAX]; 1189 time_t death = 0; 1190 u_int seconds = 0; 1191 struct dest_constraint *dest_constraints = NULL; 1192 size_t ndest_constraints = 0; 1193 struct sshkey *k = NULL; 1194 int r = SSH_ERR_INTERNAL_ERROR; 1195 1196 debug2_f("entering"); 1197 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1198 k == NULL || 1199 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1200 error_fr(r, "parse"); 1201 goto out; 1202 } 1203 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1204 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1205 error_f("failed to parse constraints"); 1206 sshbuf_reset(e->request); 1207 goto out; 1208 } 1209 1210 if (sk_provider != NULL) { 1211 if (!sshkey_is_sk(k)) { 1212 error("Cannot add provider: %s is not an " 1213 "authenticator-hosted key", sshkey_type(k)); 1214 goto out; 1215 } 1216 if (strcasecmp(sk_provider, "internal") == 0) { 1217 debug_f("internal provider"); 1218 } else { 1219 if (realpath(sk_provider, canonical_provider) == NULL) { 1220 verbose("failed provider \"%.100s\": " 1221 "realpath: %s", sk_provider, 1222 strerror(errno)); 1223 goto out; 1224 } 1225 free(sk_provider); 1226 sk_provider = xstrdup(canonical_provider); 1227 if (match_pattern_list(sk_provider, 1228 allowed_providers, 0) != 1) { 1229 error("Refusing add key: " 1230 "provider %s not allowed", sk_provider); 1231 goto out; 1232 } 1233 } 1234 } 1235 if ((r = sshkey_shield_private(k)) != 0) { 1236 error_fr(r, "shield private"); 1237 goto out; 1238 } 1239 if (lifetime && !death) 1240 death = monotime() + lifetime; 1241 if ((id = lookup_identity(k)) == NULL) { 1242 id = xcalloc(1, sizeof(Identity)); 1243 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1244 /* Increment the number of identities. */ 1245 idtab->nentries++; 1246 } else { 1247 /* identity not visible, do not update */ 1248 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1249 goto out; /* error already logged */ 1250 /* key state might have been updated */ 1251 sshkey_free(id->key); 1252 free(id->comment); 1253 free(id->sk_provider); 1254 free_dest_constraints(id->dest_constraints, 1255 id->ndest_constraints); 1256 } 1257 /* success */ 1258 id->key = k; 1259 id->comment = comment; 1260 id->death = death; 1261 id->confirm = confirm; 1262 id->sk_provider = sk_provider; 1263 id->dest_constraints = dest_constraints; 1264 id->ndest_constraints = ndest_constraints; 1265 1266 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1267 SSH_FP_DEFAULT)) == NULL) 1268 fatal_f("sshkey_fingerprint failed"); 1269 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1270 "(provider: %s) (destination constraints: %zu)", 1271 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1272 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1273 free(fp); 1274 /* transferred */ 1275 k = NULL; 1276 comment = NULL; 1277 sk_provider = NULL; 1278 dest_constraints = NULL; 1279 ndest_constraints = 0; 1280 success = 1; 1281 out: 1282 free(sk_provider); 1283 free(comment); 1284 sshkey_free(k); 1285 free_dest_constraints(dest_constraints, ndest_constraints); 1286 send_status(e, success); 1287 } 1288 1289 /* XXX todo: encrypt sensitive data with passphrase */ 1290 static void 1291 process_lock_agent(SocketEntry *e, int lock) 1292 { 1293 int r, success = 0, delay; 1294 char *passwd; 1295 u_char passwdhash[LOCK_SIZE]; 1296 static u_int fail_count = 0; 1297 size_t pwlen; 1298 1299 debug2_f("entering"); 1300 /* 1301 * This is deliberately fatal: the user has requested that we lock, 1302 * but we can't parse their request properly. The only safe thing to 1303 * do is abort. 1304 */ 1305 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1306 fatal_fr(r, "parse"); 1307 if (pwlen == 0) { 1308 debug("empty password not supported"); 1309 } else if (locked && !lock) { 1310 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1311 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1312 fatal("bcrypt_pbkdf"); 1313 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1314 debug("agent unlocked"); 1315 locked = 0; 1316 fail_count = 0; 1317 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1318 success = 1; 1319 } else { 1320 /* delay in 0.1s increments up to 10s */ 1321 if (fail_count < 100) 1322 fail_count++; 1323 delay = 100000 * fail_count; 1324 debug("unlock failed, delaying %0.1lf seconds", 1325 (double)delay/1000000); 1326 usleep(delay); 1327 } 1328 explicit_bzero(passwdhash, sizeof(passwdhash)); 1329 } else if (!locked && lock) { 1330 debug("agent locked"); 1331 locked = 1; 1332 arc4random_buf(lock_salt, sizeof(lock_salt)); 1333 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1334 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1335 fatal("bcrypt_pbkdf"); 1336 success = 1; 1337 } 1338 freezero(passwd, pwlen); 1339 send_status(e, success); 1340 } 1341 1342 static void 1343 no_identities(SocketEntry *e) 1344 { 1345 struct sshbuf *msg; 1346 int r; 1347 1348 if ((msg = sshbuf_new()) == NULL) 1349 fatal_f("sshbuf_new failed"); 1350 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1351 (r = sshbuf_put_u32(msg, 0)) != 0 || 1352 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1353 fatal_fr(r, "compose"); 1354 sshbuf_free(msg); 1355 } 1356 1357 #ifdef ENABLE_PKCS11 1358 static void 1359 process_add_smartcard_key(SocketEntry *e) 1360 { 1361 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1362 char **comments = NULL; 1363 int r, i, count = 0, success = 0, confirm = 0; 1364 u_int seconds = 0; 1365 time_t death = 0; 1366 struct sshkey **keys = NULL, *k; 1367 Identity *id; 1368 struct dest_constraint *dest_constraints = NULL; 1369 size_t ndest_constraints = 0; 1370 1371 debug2_f("entering"); 1372 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1373 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1374 error_fr(r, "parse"); 1375 goto send; 1376 } 1377 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1378 NULL, &dest_constraints, &ndest_constraints) != 0) { 1379 error_f("failed to parse constraints"); 1380 goto send; 1381 } 1382 if (realpath(provider, canonical_provider) == NULL) { 1383 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1384 provider, strerror(errno)); 1385 goto send; 1386 } 1387 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1388 verbose("refusing PKCS#11 add of \"%.100s\": " 1389 "provider not allowed", canonical_provider); 1390 goto send; 1391 } 1392 debug_f("add %.100s", canonical_provider); 1393 if (lifetime && !death) 1394 death = monotime() + lifetime; 1395 1396 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1397 for (i = 0; i < count; i++) { 1398 k = keys[i]; 1399 if (lookup_identity(k) == NULL) { 1400 id = xcalloc(1, sizeof(Identity)); 1401 id->key = k; 1402 keys[i] = NULL; /* transferred */ 1403 id->provider = xstrdup(canonical_provider); 1404 if (*comments[i] != '\0') { 1405 id->comment = comments[i]; 1406 comments[i] = NULL; /* transferred */ 1407 } else { 1408 id->comment = xstrdup(canonical_provider); 1409 } 1410 id->death = death; 1411 id->confirm = confirm; 1412 id->dest_constraints = dest_constraints; 1413 id->ndest_constraints = ndest_constraints; 1414 dest_constraints = NULL; /* transferred */ 1415 ndest_constraints = 0; 1416 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1417 idtab->nentries++; 1418 success = 1; 1419 } 1420 /* XXX update constraints for existing keys */ 1421 sshkey_free(keys[i]); 1422 free(comments[i]); 1423 } 1424 send: 1425 free(pin); 1426 free(provider); 1427 free(keys); 1428 free(comments); 1429 free_dest_constraints(dest_constraints, ndest_constraints); 1430 send_status(e, success); 1431 } 1432 1433 static void 1434 process_remove_smartcard_key(SocketEntry *e) 1435 { 1436 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1437 int r, success = 0; 1438 Identity *id, *nxt; 1439 1440 debug2_f("entering"); 1441 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1442 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1443 error_fr(r, "parse"); 1444 goto send; 1445 } 1446 free(pin); 1447 1448 if (realpath(provider, canonical_provider) == NULL) { 1449 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1450 provider, strerror(errno)); 1451 goto send; 1452 } 1453 1454 debug_f("remove %.100s", canonical_provider); 1455 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1456 nxt = TAILQ_NEXT(id, next); 1457 /* Skip file--based keys */ 1458 if (id->provider == NULL) 1459 continue; 1460 if (!strcmp(canonical_provider, id->provider)) { 1461 TAILQ_REMOVE(&idtab->idlist, id, next); 1462 free_identity(id); 1463 idtab->nentries--; 1464 } 1465 } 1466 if (pkcs11_del_provider(canonical_provider) == 0) 1467 success = 1; 1468 else 1469 error_f("pkcs11_del_provider failed"); 1470 send: 1471 free(provider); 1472 send_status(e, success); 1473 } 1474 #endif /* ENABLE_PKCS11 */ 1475 1476 static int 1477 process_ext_session_bind(SocketEntry *e) 1478 { 1479 int r, sid_match, key_match; 1480 struct sshkey *key = NULL; 1481 struct sshbuf *sid = NULL, *sig = NULL; 1482 char *fp = NULL; 1483 size_t i; 1484 u_char fwd = 0; 1485 1486 debug2_f("entering"); 1487 if ((r = sshkey_froms(e->request, &key)) != 0 || 1488 (r = sshbuf_froms(e->request, &sid)) != 0 || 1489 (r = sshbuf_froms(e->request, &sig)) != 0 || 1490 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1491 error_fr(r, "parse"); 1492 goto out; 1493 } 1494 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1495 SSH_FP_DEFAULT)) == NULL) 1496 fatal_f("fingerprint failed"); 1497 /* check signature with hostkey on session ID */ 1498 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1499 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1500 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1501 goto out; 1502 } 1503 /* check whether sid/key already recorded */ 1504 for (i = 0; i < e->nsession_ids; i++) { 1505 if (!e->session_ids[i].forwarded) { 1506 error_f("attempt to bind session ID to socket " 1507 "previously bound for authentication attempt"); 1508 r = -1; 1509 goto out; 1510 } 1511 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1512 key_match = sshkey_equal(key, e->session_ids[i].key); 1513 if (sid_match && key_match) { 1514 debug_f("session ID already recorded for %s %s", 1515 sshkey_type(key), fp); 1516 r = 0; 1517 goto out; 1518 } else if (sid_match) { 1519 error_f("session ID recorded against different key " 1520 "for %s %s", sshkey_type(key), fp); 1521 r = -1; 1522 goto out; 1523 } 1524 /* 1525 * new sid with previously-seen key can happen, e.g. multiple 1526 * connections to the same host. 1527 */ 1528 } 1529 /* record new key/sid */ 1530 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1531 error_f("too many session IDs recorded"); 1532 goto out; 1533 } 1534 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1535 e->nsession_ids + 1, sizeof(*e->session_ids)); 1536 i = e->nsession_ids++; 1537 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1538 AGENT_MAX_SESSION_IDS); 1539 e->session_ids[i].key = key; 1540 e->session_ids[i].forwarded = fwd != 0; 1541 key = NULL; /* transferred */ 1542 /* can't transfer sid; it's refcounted and scoped to request's life */ 1543 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1544 fatal_f("sshbuf_new"); 1545 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1546 fatal_fr(r, "sshbuf_putb session ID"); 1547 /* success */ 1548 r = 0; 1549 out: 1550 free(fp); 1551 sshkey_free(key); 1552 sshbuf_free(sid); 1553 sshbuf_free(sig); 1554 return r == 0 ? 1 : 0; 1555 } 1556 1557 static void 1558 process_extension(SocketEntry *e) 1559 { 1560 int r, success = 0; 1561 char *name; 1562 1563 debug2_f("entering"); 1564 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1565 error_fr(r, "parse"); 1566 goto send; 1567 } 1568 if (strcmp(name, "session-bind@openssh.com") == 0) 1569 success = process_ext_session_bind(e); 1570 else 1571 debug_f("unsupported extension \"%s\"", name); 1572 free(name); 1573 send: 1574 send_status(e, success); 1575 } 1576 /* 1577 * dispatch incoming message. 1578 * returns 1 on success, 0 for incomplete messages or -1 on error. 1579 */ 1580 static int 1581 process_message(u_int socknum) 1582 { 1583 u_int msg_len; 1584 u_char type; 1585 const u_char *cp; 1586 int r; 1587 SocketEntry *e; 1588 1589 if (socknum >= sockets_alloc) 1590 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1591 e = &sockets[socknum]; 1592 1593 if (sshbuf_len(e->input) < 5) 1594 return 0; /* Incomplete message header. */ 1595 cp = sshbuf_ptr(e->input); 1596 msg_len = PEEK_U32(cp); 1597 if (msg_len > AGENT_MAX_LEN) { 1598 debug_f("socket %u (fd=%d) message too long %u > %u", 1599 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1600 return -1; 1601 } 1602 if (sshbuf_len(e->input) < msg_len + 4) 1603 return 0; /* Incomplete message body. */ 1604 1605 /* move the current input to e->request */ 1606 sshbuf_reset(e->request); 1607 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1608 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1609 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1610 r == SSH_ERR_STRING_TOO_LARGE) { 1611 error_fr(r, "parse"); 1612 return -1; 1613 } 1614 fatal_fr(r, "parse"); 1615 } 1616 1617 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1618 1619 /* check whether agent is locked */ 1620 if (locked && type != SSH_AGENTC_UNLOCK) { 1621 sshbuf_reset(e->request); 1622 switch (type) { 1623 case SSH2_AGENTC_REQUEST_IDENTITIES: 1624 /* send empty lists */ 1625 no_identities(e); 1626 break; 1627 default: 1628 /* send a fail message for all other request types */ 1629 send_status(e, 0); 1630 } 1631 return 1; 1632 } 1633 1634 switch (type) { 1635 case SSH_AGENTC_LOCK: 1636 case SSH_AGENTC_UNLOCK: 1637 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1638 break; 1639 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1640 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1641 break; 1642 /* ssh2 */ 1643 case SSH2_AGENTC_SIGN_REQUEST: 1644 process_sign_request2(e); 1645 break; 1646 case SSH2_AGENTC_REQUEST_IDENTITIES: 1647 process_request_identities(e); 1648 break; 1649 case SSH2_AGENTC_ADD_IDENTITY: 1650 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1651 process_add_identity(e); 1652 break; 1653 case SSH2_AGENTC_REMOVE_IDENTITY: 1654 process_remove_identity(e); 1655 break; 1656 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1657 process_remove_all_identities(e); 1658 break; 1659 #ifdef ENABLE_PKCS11 1660 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1661 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1662 process_add_smartcard_key(e); 1663 break; 1664 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1665 process_remove_smartcard_key(e); 1666 break; 1667 #endif /* ENABLE_PKCS11 */ 1668 case SSH_AGENTC_EXTENSION: 1669 process_extension(e); 1670 break; 1671 default: 1672 /* Unknown message. Respond with failure. */ 1673 error("Unknown message %d", type); 1674 sshbuf_reset(e->request); 1675 send_status(e, 0); 1676 break; 1677 } 1678 return 1; 1679 } 1680 1681 static void 1682 new_socket(sock_type type, int fd) 1683 { 1684 u_int i, old_alloc, new_alloc; 1685 1686 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1687 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1688 set_nonblock(fd); 1689 1690 if (fd > max_fd) 1691 max_fd = fd; 1692 1693 for (i = 0; i < sockets_alloc; i++) 1694 if (sockets[i].type == AUTH_UNUSED) { 1695 sockets[i].fd = fd; 1696 if ((sockets[i].input = sshbuf_new()) == NULL || 1697 (sockets[i].output = sshbuf_new()) == NULL || 1698 (sockets[i].request = sshbuf_new()) == NULL) 1699 fatal_f("sshbuf_new failed"); 1700 sockets[i].type = type; 1701 return; 1702 } 1703 old_alloc = sockets_alloc; 1704 new_alloc = sockets_alloc + 10; 1705 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1706 sizeof(sockets[0])); 1707 for (i = old_alloc; i < new_alloc; i++) 1708 sockets[i].type = AUTH_UNUSED; 1709 sockets_alloc = new_alloc; 1710 sockets[old_alloc].fd = fd; 1711 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1712 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1713 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1714 fatal_f("sshbuf_new failed"); 1715 sockets[old_alloc].type = type; 1716 } 1717 1718 static int 1719 handle_socket_read(u_int socknum) 1720 { 1721 struct sockaddr_un sunaddr; 1722 socklen_t slen; 1723 uid_t euid; 1724 gid_t egid; 1725 int fd; 1726 1727 slen = sizeof(sunaddr); 1728 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1729 if (fd == -1) { 1730 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1731 return -1; 1732 } 1733 if (getpeereid(fd, &euid, &egid) == -1) { 1734 error("getpeereid %d failed: %s", fd, strerror(errno)); 1735 close(fd); 1736 return -1; 1737 } 1738 if ((euid != 0) && (getuid() != euid)) { 1739 error("uid mismatch: peer euid %u != uid %u", 1740 (u_int) euid, (u_int) getuid()); 1741 close(fd); 1742 return -1; 1743 } 1744 new_socket(AUTH_CONNECTION, fd); 1745 return 0; 1746 } 1747 1748 static int 1749 handle_conn_read(u_int socknum) 1750 { 1751 char buf[AGENT_RBUF_LEN]; 1752 ssize_t len; 1753 int r; 1754 1755 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1756 if (len == -1) { 1757 if (errno == EAGAIN || errno == EINTR) 1758 return 0; 1759 error_f("read error on socket %u (fd %d): %s", 1760 socknum, sockets[socknum].fd, strerror(errno)); 1761 } 1762 return -1; 1763 } 1764 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1765 fatal_fr(r, "compose"); 1766 explicit_bzero(buf, sizeof(buf)); 1767 for (;;) { 1768 if ((r = process_message(socknum)) == -1) 1769 return -1; 1770 else if (r == 0) 1771 break; 1772 } 1773 return 0; 1774 } 1775 1776 static int 1777 handle_conn_write(u_int socknum) 1778 { 1779 ssize_t len; 1780 int r; 1781 1782 if (sshbuf_len(sockets[socknum].output) == 0) 1783 return 0; /* shouldn't happen */ 1784 if ((len = write(sockets[socknum].fd, 1785 sshbuf_ptr(sockets[socknum].output), 1786 sshbuf_len(sockets[socknum].output))) <= 0) { 1787 if (len == -1) { 1788 if (errno == EAGAIN || errno == EINTR) 1789 return 0; 1790 error_f("read error on socket %u (fd %d): %s", 1791 socknum, sockets[socknum].fd, strerror(errno)); 1792 } 1793 return -1; 1794 } 1795 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1796 fatal_fr(r, "consume"); 1797 return 0; 1798 } 1799 1800 static void 1801 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1802 { 1803 size_t i; 1804 u_int socknum, activefds = npfd; 1805 1806 for (i = 0; i < npfd; i++) { 1807 if (pfd[i].revents == 0) 1808 continue; 1809 /* Find sockets entry */ 1810 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1811 if (sockets[socknum].type != AUTH_SOCKET && 1812 sockets[socknum].type != AUTH_CONNECTION) 1813 continue; 1814 if (pfd[i].fd == sockets[socknum].fd) 1815 break; 1816 } 1817 if (socknum >= sockets_alloc) { 1818 error_f("no socket for fd %d", pfd[i].fd); 1819 continue; 1820 } 1821 /* Process events */ 1822 switch (sockets[socknum].type) { 1823 case AUTH_SOCKET: 1824 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1825 break; 1826 if (npfd > maxfds) { 1827 debug3("out of fds (active %u >= limit %u); " 1828 "skipping accept", activefds, maxfds); 1829 break; 1830 } 1831 if (handle_socket_read(socknum) == 0) 1832 activefds++; 1833 break; 1834 case AUTH_CONNECTION: 1835 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1836 handle_conn_read(socknum) != 0) 1837 goto close_sock; 1838 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1839 handle_conn_write(socknum) != 0) { 1840 close_sock: 1841 if (activefds == 0) 1842 fatal("activefds == 0 at close_sock"); 1843 close_socket(&sockets[socknum]); 1844 activefds--; 1845 break; 1846 } 1847 break; 1848 default: 1849 break; 1850 } 1851 } 1852 } 1853 1854 static int 1855 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1856 { 1857 struct pollfd *pfd = *pfdp; 1858 size_t i, j, npfd = 0; 1859 time_t deadline; 1860 int r; 1861 1862 /* Count active sockets */ 1863 for (i = 0; i < sockets_alloc; i++) { 1864 switch (sockets[i].type) { 1865 case AUTH_SOCKET: 1866 case AUTH_CONNECTION: 1867 npfd++; 1868 break; 1869 case AUTH_UNUSED: 1870 break; 1871 default: 1872 fatal("Unknown socket type %d", sockets[i].type); 1873 break; 1874 } 1875 } 1876 if (npfd != *npfdp && 1877 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1878 fatal_f("recallocarray failed"); 1879 *pfdp = pfd; 1880 *npfdp = npfd; 1881 1882 for (i = j = 0; i < sockets_alloc; i++) { 1883 switch (sockets[i].type) { 1884 case AUTH_SOCKET: 1885 if (npfd > maxfds) { 1886 debug3("out of fds (active %zu >= limit %u); " 1887 "skipping arming listener", npfd, maxfds); 1888 break; 1889 } 1890 pfd[j].fd = sockets[i].fd; 1891 pfd[j].revents = 0; 1892 pfd[j].events = POLLIN; 1893 j++; 1894 break; 1895 case AUTH_CONNECTION: 1896 pfd[j].fd = sockets[i].fd; 1897 pfd[j].revents = 0; 1898 /* 1899 * Only prepare to read if we can handle a full-size 1900 * input read buffer and enqueue a max size reply.. 1901 */ 1902 if ((r = sshbuf_check_reserve(sockets[i].input, 1903 AGENT_RBUF_LEN)) == 0 && 1904 (r = sshbuf_check_reserve(sockets[i].output, 1905 AGENT_MAX_LEN)) == 0) 1906 pfd[j].events = POLLIN; 1907 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1908 fatal_fr(r, "reserve"); 1909 if (sshbuf_len(sockets[i].output) > 0) 1910 pfd[j].events |= POLLOUT; 1911 j++; 1912 break; 1913 default: 1914 break; 1915 } 1916 } 1917 deadline = reaper(); 1918 if (parent_alive_interval != 0) 1919 deadline = (deadline == 0) ? parent_alive_interval : 1920 MINIMUM(deadline, parent_alive_interval); 1921 if (deadline == 0) { 1922 *timeoutp = -1; /* INFTIM */ 1923 } else { 1924 if (deadline > INT_MAX / 1000) 1925 *timeoutp = INT_MAX / 1000; 1926 else 1927 *timeoutp = deadline * 1000; 1928 } 1929 return (1); 1930 } 1931 1932 static void 1933 cleanup_socket(void) 1934 { 1935 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1936 return; 1937 debug_f("cleanup"); 1938 if (socket_name[0]) 1939 unlink(socket_name); 1940 if (socket_dir[0]) 1941 rmdir(socket_dir); 1942 } 1943 1944 void 1945 cleanup_exit(int i) 1946 { 1947 cleanup_socket(); 1948 _exit(i); 1949 } 1950 1951 /*ARGSUSED*/ 1952 static void 1953 cleanup_handler(int sig) 1954 { 1955 cleanup_socket(); 1956 #ifdef ENABLE_PKCS11 1957 pkcs11_terminate(); 1958 #endif 1959 _exit(2); 1960 } 1961 1962 static void 1963 check_parent_exists(void) 1964 { 1965 /* 1966 * If our parent has exited then getppid() will return (pid_t)1, 1967 * so testing for that should be safe. 1968 */ 1969 if (parent_pid != -1 && getppid() != parent_pid) { 1970 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1971 cleanup_socket(); 1972 _exit(2); 1973 } 1974 } 1975 1976 static void 1977 usage(void) 1978 { 1979 fprintf(stderr, 1980 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1981 " [-O option] [-P allowed_providers] [-t life]\n" 1982 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 1983 " [-P allowed_providers] [-t life] command [arg ...]\n" 1984 " ssh-agent [-c | -s] -k\n"); 1985 exit(1); 1986 } 1987 1988 int 1989 main(int ac, char **av) 1990 { 1991 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1992 int sock, ch, result, saved_errno; 1993 char *shell, *format, *pidstr, *agentsocket = NULL; 1994 struct rlimit rlim; 1995 extern int optind; 1996 extern char *optarg; 1997 pid_t pid; 1998 char pidstrbuf[1 + 3 * sizeof pid]; 1999 size_t len; 2000 mode_t prev_mask; 2001 int timeout = -1; /* INFTIM */ 2002 struct pollfd *pfd = NULL; 2003 size_t npfd = 0; 2004 u_int maxfds; 2005 2006 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2007 sanitise_stdfd(); 2008 2009 /* drop */ 2010 setegid(getgid()); 2011 setgid(getgid()); 2012 2013 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2014 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2015 2016 #ifdef WITH_OPENSSL 2017 OpenSSL_add_all_algorithms(); 2018 #endif 2019 2020 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2021 switch (ch) { 2022 case 'E': 2023 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2024 if (fingerprint_hash == -1) 2025 fatal("Invalid hash algorithm \"%s\"", optarg); 2026 break; 2027 case 'c': 2028 if (s_flag) 2029 usage(); 2030 c_flag++; 2031 break; 2032 case 'k': 2033 k_flag++; 2034 break; 2035 case 'O': 2036 if (strcmp(optarg, "no-restrict-websafe") == 0) 2037 restrict_websafe = 0; 2038 else 2039 fatal("Unknown -O option"); 2040 break; 2041 case 'P': 2042 if (allowed_providers != NULL) 2043 fatal("-P option already specified"); 2044 allowed_providers = xstrdup(optarg); 2045 break; 2046 case 's': 2047 if (c_flag) 2048 usage(); 2049 s_flag++; 2050 break; 2051 case 'd': 2052 if (d_flag || D_flag) 2053 usage(); 2054 d_flag++; 2055 break; 2056 case 'D': 2057 if (d_flag || D_flag) 2058 usage(); 2059 D_flag++; 2060 break; 2061 case 'a': 2062 agentsocket = optarg; 2063 break; 2064 case 't': 2065 if ((lifetime = convtime(optarg)) == -1) { 2066 fprintf(stderr, "Invalid lifetime\n"); 2067 usage(); 2068 } 2069 break; 2070 default: 2071 usage(); 2072 } 2073 } 2074 ac -= optind; 2075 av += optind; 2076 2077 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2078 usage(); 2079 2080 if (allowed_providers == NULL) 2081 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2082 2083 if (ac == 0 && !c_flag && !s_flag) { 2084 shell = getenv("SHELL"); 2085 if (shell != NULL && (len = strlen(shell)) > 2 && 2086 strncmp(shell + len - 3, "csh", 3) == 0) 2087 c_flag = 1; 2088 } 2089 if (k_flag) { 2090 const char *errstr = NULL; 2091 2092 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2093 if (pidstr == NULL) { 2094 fprintf(stderr, "%s not set, cannot kill agent\n", 2095 SSH_AGENTPID_ENV_NAME); 2096 exit(1); 2097 } 2098 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2099 if (errstr) { 2100 fprintf(stderr, 2101 "%s=\"%s\", which is not a good PID: %s\n", 2102 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2103 exit(1); 2104 } 2105 if (kill(pid, SIGTERM) == -1) { 2106 perror("kill"); 2107 exit(1); 2108 } 2109 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2110 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2111 printf(format, SSH_AGENTPID_ENV_NAME); 2112 printf("echo Agent pid %ld killed;\n", (long)pid); 2113 exit(0); 2114 } 2115 2116 /* 2117 * Minimum file descriptors: 2118 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2119 * a few spare for libc / stack protectors / sanitisers, etc. 2120 */ 2121 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2122 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2123 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2124 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2125 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2126 2127 parent_pid = getpid(); 2128 2129 if (agentsocket == NULL) { 2130 /* Create private directory for agent socket */ 2131 mktemp_proto(socket_dir, sizeof(socket_dir)); 2132 if (mkdtemp(socket_dir) == NULL) { 2133 perror("mkdtemp: private socket dir"); 2134 exit(1); 2135 } 2136 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2137 (long)parent_pid); 2138 } else { 2139 /* Try to use specified agent socket */ 2140 socket_dir[0] = '\0'; 2141 strlcpy(socket_name, agentsocket, sizeof socket_name); 2142 } 2143 2144 /* 2145 * Create socket early so it will exist before command gets run from 2146 * the parent. 2147 */ 2148 prev_mask = umask(0177); 2149 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2150 if (sock < 0) { 2151 /* XXX - unix_listener() calls error() not perror() */ 2152 *socket_name = '\0'; /* Don't unlink any existing file */ 2153 cleanup_exit(1); 2154 } 2155 umask(prev_mask); 2156 2157 /* 2158 * Fork, and have the parent execute the command, if any, or present 2159 * the socket data. The child continues as the authentication agent. 2160 */ 2161 if (D_flag || d_flag) { 2162 log_init(__progname, 2163 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2164 SYSLOG_FACILITY_AUTH, 1); 2165 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2166 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2167 SSH_AUTHSOCKET_ENV_NAME); 2168 printf("echo Agent pid %ld;\n", (long)parent_pid); 2169 fflush(stdout); 2170 goto skip; 2171 } 2172 pid = fork(); 2173 if (pid == -1) { 2174 perror("fork"); 2175 cleanup_exit(1); 2176 } 2177 if (pid != 0) { /* Parent - execute the given command. */ 2178 close(sock); 2179 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2180 if (ac == 0) { 2181 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2182 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2183 SSH_AUTHSOCKET_ENV_NAME); 2184 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2185 SSH_AGENTPID_ENV_NAME); 2186 printf("echo Agent pid %ld;\n", (long)pid); 2187 exit(0); 2188 } 2189 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2190 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2191 perror("setenv"); 2192 exit(1); 2193 } 2194 execvp(av[0], av); 2195 perror(av[0]); 2196 exit(1); 2197 } 2198 /* child */ 2199 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2200 2201 if (setsid() == -1) { 2202 error("setsid: %s", strerror(errno)); 2203 cleanup_exit(1); 2204 } 2205 2206 (void)chdir("/"); 2207 if (stdfd_devnull(1, 1, 1) == -1) 2208 error_f("stdfd_devnull failed"); 2209 2210 /* deny core dumps, since memory contains unencrypted private keys */ 2211 rlim.rlim_cur = rlim.rlim_max = 0; 2212 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2213 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2214 cleanup_exit(1); 2215 } 2216 2217 skip: 2218 2219 cleanup_pid = getpid(); 2220 2221 #ifdef ENABLE_PKCS11 2222 pkcs11_init(0); 2223 #endif 2224 new_socket(AUTH_SOCKET, sock); 2225 if (ac > 0) 2226 parent_alive_interval = 10; 2227 idtab_init(); 2228 ssh_signal(SIGPIPE, SIG_IGN); 2229 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2230 ssh_signal(SIGHUP, cleanup_handler); 2231 ssh_signal(SIGTERM, cleanup_handler); 2232 2233 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2234 fatal("%s: pledge: %s", __progname, strerror(errno)); 2235 2236 while (1) { 2237 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2238 result = poll(pfd, npfd, timeout); 2239 saved_errno = errno; 2240 if (parent_alive_interval != 0) 2241 check_parent_exists(); 2242 (void) reaper(); /* remove expired keys */ 2243 if (result == -1) { 2244 if (saved_errno == EINTR) 2245 continue; 2246 fatal("poll: %s", strerror(saved_errno)); 2247 } else if (result > 0) 2248 after_poll(pfd, npfd, maxfds); 2249 } 2250 /* NOTREACHED */ 2251 } 2252