1 /* $OpenBSD: ssh-agent.c,v 1.293 2022/10/07 06:00:58 jmc Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include <sys/types.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/resource.h> 41 #include <sys/socket.h> 42 #include <sys/stat.h> 43 #include <sys/un.h> 44 #include <sys/wait.h> 45 46 #ifdef WITH_OPENSSL 47 #include <openssl/evp.h> 48 #endif 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <paths.h> 53 #include <poll.h> 54 #include <signal.h> 55 #include <stdlib.h> 56 #include <stdio.h> 57 #include <string.h> 58 #include <stdarg.h> 59 #include <limits.h> 60 #include <time.h> 61 #include <unistd.h> 62 #include <util.h> 63 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh2.h" 67 #include "sshbuf.h" 68 #include "sshkey.h" 69 #include "authfd.h" 70 #include "compat.h" 71 #include "log.h" 72 #include "misc.h" 73 #include "digest.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "msg.h" 77 #include "ssherr.h" 78 #include "pathnames.h" 79 #include "ssh-pkcs11.h" 80 #include "sk-api.h" 81 #include "myproposal.h" 82 83 #ifndef DEFAULT_ALLOWED_PROVIDERS 84 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 85 #endif 86 87 /* Maximum accepted message length */ 88 #define AGENT_MAX_LEN (256*1024) 89 /* Maximum bytes to read from client socket */ 90 #define AGENT_RBUF_LEN (4096) 91 /* Maximum number of recorded session IDs/hostkeys per connection */ 92 #define AGENT_MAX_SESSION_IDS 16 93 /* Maximum size of session ID */ 94 #define AGENT_MAX_SID_LEN 128 95 /* Maximum number of destination constraints to accept on a key */ 96 #define AGENT_MAX_DEST_CONSTRAINTS 1024 97 98 /* XXX store hostkey_sid in a refcounted tree */ 99 100 typedef enum { 101 AUTH_UNUSED = 0, 102 AUTH_SOCKET = 1, 103 AUTH_CONNECTION = 2, 104 } sock_type; 105 106 struct hostkey_sid { 107 struct sshkey *key; 108 struct sshbuf *sid; 109 int forwarded; 110 }; 111 112 typedef struct socket_entry { 113 int fd; 114 sock_type type; 115 struct sshbuf *input; 116 struct sshbuf *output; 117 struct sshbuf *request; 118 size_t nsession_ids; 119 struct hostkey_sid *session_ids; 120 } SocketEntry; 121 122 u_int sockets_alloc = 0; 123 SocketEntry *sockets = NULL; 124 125 typedef struct identity { 126 TAILQ_ENTRY(identity) next; 127 struct sshkey *key; 128 char *comment; 129 char *provider; 130 time_t death; 131 u_int confirm; 132 char *sk_provider; 133 struct dest_constraint *dest_constraints; 134 size_t ndest_constraints; 135 } Identity; 136 137 struct idtable { 138 int nentries; 139 TAILQ_HEAD(idqueue, identity) idlist; 140 }; 141 142 /* private key table */ 143 struct idtable *idtab; 144 145 int max_fd = 0; 146 147 /* pid of shell == parent of agent */ 148 pid_t parent_pid = -1; 149 time_t parent_alive_interval = 0; 150 151 /* pid of process for which cleanup_socket is applicable */ 152 pid_t cleanup_pid = 0; 153 154 /* pathname and directory for AUTH_SOCKET */ 155 char socket_name[PATH_MAX]; 156 char socket_dir[PATH_MAX]; 157 158 /* Pattern-list of allowed PKCS#11/Security key paths */ 159 static char *allowed_providers; 160 161 /* locking */ 162 #define LOCK_SIZE 32 163 #define LOCK_SALT_SIZE 16 164 #define LOCK_ROUNDS 1 165 int locked = 0; 166 u_char lock_pwhash[LOCK_SIZE]; 167 u_char lock_salt[LOCK_SALT_SIZE]; 168 169 extern char *__progname; 170 171 /* Default lifetime in seconds (0 == forever) */ 172 static int lifetime = 0; 173 174 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 175 176 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 177 static int restrict_websafe = 1; 178 179 static void 180 close_socket(SocketEntry *e) 181 { 182 size_t i; 183 184 close(e->fd); 185 sshbuf_free(e->input); 186 sshbuf_free(e->output); 187 sshbuf_free(e->request); 188 for (i = 0; i < e->nsession_ids; i++) { 189 sshkey_free(e->session_ids[i].key); 190 sshbuf_free(e->session_ids[i].sid); 191 } 192 free(e->session_ids); 193 memset(e, '\0', sizeof(*e)); 194 e->fd = -1; 195 e->type = AUTH_UNUSED; 196 } 197 198 static void 199 idtab_init(void) 200 { 201 idtab = xcalloc(1, sizeof(*idtab)); 202 TAILQ_INIT(&idtab->idlist); 203 idtab->nentries = 0; 204 } 205 206 static void 207 free_dest_constraint_hop(struct dest_constraint_hop *dch) 208 { 209 u_int i; 210 211 if (dch == NULL) 212 return; 213 free(dch->user); 214 free(dch->hostname); 215 for (i = 0; i < dch->nkeys; i++) 216 sshkey_free(dch->keys[i]); 217 free(dch->keys); 218 free(dch->key_is_ca); 219 } 220 221 static void 222 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 223 { 224 size_t i; 225 226 for (i = 0; i < ndcs; i++) { 227 free_dest_constraint_hop(&dcs[i].from); 228 free_dest_constraint_hop(&dcs[i].to); 229 } 230 free(dcs); 231 } 232 233 static void 234 free_identity(Identity *id) 235 { 236 sshkey_free(id->key); 237 free(id->provider); 238 free(id->comment); 239 free(id->sk_provider); 240 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 241 free(id); 242 } 243 244 /* 245 * Match 'key' against the key/CA list in a destination constraint hop 246 * Returns 0 on success or -1 otherwise. 247 */ 248 static int 249 match_key_hop(const char *tag, const struct sshkey *key, 250 const struct dest_constraint_hop *dch) 251 { 252 const char *reason = NULL; 253 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 254 u_int i; 255 char *fp; 256 257 if (key == NULL) 258 return -1; 259 /* XXX logspam */ 260 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 261 SSH_FP_DEFAULT)) == NULL) 262 fatal_f("fingerprint failed"); 263 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 264 tag, hostname, sshkey_type(key), fp, dch->nkeys); 265 free(fp); 266 for (i = 0; i < dch->nkeys; i++) { 267 if (dch->keys[i] == NULL) 268 return -1; 269 /* XXX logspam */ 270 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 271 SSH_FP_DEFAULT)) == NULL) 272 fatal_f("fingerprint failed"); 273 debug3_f("%s: key %u: %s%s %s", tag, i, 274 dch->key_is_ca[i] ? "CA " : "", 275 sshkey_type(dch->keys[i]), fp); 276 free(fp); 277 if (!sshkey_is_cert(key)) { 278 /* plain key */ 279 if (dch->key_is_ca[i] || 280 !sshkey_equal(key, dch->keys[i])) 281 continue; 282 return 0; 283 } 284 /* certificate */ 285 if (!dch->key_is_ca[i]) 286 continue; 287 if (key->cert == NULL || key->cert->signature_key == NULL) 288 return -1; /* shouldn't happen */ 289 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 290 continue; 291 if (sshkey_cert_check_host(key, hostname, 1, 292 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 293 debug_f("cert %s / hostname %s rejected: %s", 294 key->cert->key_id, hostname, reason); 295 continue; 296 } 297 return 0; 298 } 299 return -1; 300 } 301 302 /* Check destination constraints on an identity against the hostkey/user */ 303 static int 304 permitted_by_dest_constraints(const struct sshkey *fromkey, 305 const struct sshkey *tokey, Identity *id, const char *user, 306 const char **hostnamep) 307 { 308 size_t i; 309 struct dest_constraint *d; 310 311 if (hostnamep != NULL) 312 *hostnamep = NULL; 313 for (i = 0; i < id->ndest_constraints; i++) { 314 d = id->dest_constraints + i; 315 /* XXX remove logspam */ 316 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 317 i, d->from.user ? d->from.user : "", 318 d->from.user ? "@" : "", 319 d->from.hostname ? d->from.hostname : "(ORIGIN)", 320 d->from.nkeys, 321 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 322 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 323 324 /* Match 'from' key */ 325 if (fromkey == NULL) { 326 /* We are matching the first hop */ 327 if (d->from.hostname != NULL || d->from.nkeys != 0) 328 continue; 329 } else if (match_key_hop("from", fromkey, &d->from) != 0) 330 continue; 331 332 /* Match 'to' key */ 333 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 334 continue; 335 336 /* Match user if specified */ 337 if (d->to.user != NULL && user != NULL && 338 !match_pattern(user, d->to.user)) 339 continue; 340 341 /* successfully matched this constraint */ 342 if (hostnamep != NULL) 343 *hostnamep = d->to.hostname; 344 debug2_f("allowed for hostname %s", 345 d->to.hostname == NULL ? "*" : d->to.hostname); 346 return 0; 347 } 348 /* no match */ 349 debug2_f("%s identity \"%s\" not permitted for this destination", 350 sshkey_type(id->key), id->comment); 351 return -1; 352 } 353 354 /* 355 * Check whether hostkeys on a SocketEntry and the optionally specified user 356 * are permitted by the destination constraints on the Identity. 357 * Returns 0 on success or -1 otherwise. 358 */ 359 static int 360 identity_permitted(Identity *id, SocketEntry *e, char *user, 361 const char **forward_hostnamep, const char **last_hostnamep) 362 { 363 size_t i; 364 const char **hp; 365 struct hostkey_sid *hks; 366 const struct sshkey *fromkey = NULL; 367 const char *test_user; 368 char *fp1, *fp2; 369 370 /* XXX remove logspam */ 371 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 372 "%zu constraints", sshkey_type(id->key), id->comment, 373 e->nsession_ids, id->ndest_constraints); 374 if (id->ndest_constraints == 0) 375 return 0; /* unconstrained */ 376 if (e->nsession_ids == 0) 377 return 0; /* local use */ 378 /* 379 * Walk through the hops recorded by session_id and try to find a 380 * constraint that satisfies each. 381 */ 382 for (i = 0; i < e->nsession_ids; i++) { 383 hks = e->session_ids + i; 384 if (hks->key == NULL) 385 fatal_f("internal error: no bound key"); 386 /* XXX remove logspam */ 387 fp1 = fp2 = NULL; 388 if (fromkey != NULL && 389 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 390 SSH_FP_DEFAULT)) == NULL) 391 fatal_f("fingerprint failed"); 392 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 393 SSH_FP_DEFAULT)) == NULL) 394 fatal_f("fingerprint failed"); 395 debug3_f("socketentry fd=%d, entry %zu %s, " 396 "from hostkey %s %s to user %s hostkey %s %s", 397 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 398 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 399 fromkey ? fp1 : "", user ? user : "(ANY)", 400 sshkey_type(hks->key), fp2); 401 free(fp1); 402 free(fp2); 403 /* 404 * Record the hostnames for the initial forwarding and 405 * the final destination. 406 */ 407 hp = NULL; 408 if (i == e->nsession_ids - 1) 409 hp = last_hostnamep; 410 else if (i == 0) 411 hp = forward_hostnamep; 412 /* Special handling for final recorded binding */ 413 test_user = NULL; 414 if (i == e->nsession_ids - 1) { 415 /* Can only check user at final hop */ 416 test_user = user; 417 /* 418 * user is only presented for signature requests. 419 * If this is the case, make sure last binding is not 420 * for a forwarding. 421 */ 422 if (hks->forwarded && user != NULL) { 423 error_f("tried to sign on forwarding hop"); 424 return -1; 425 } 426 } else if (!hks->forwarded) { 427 error_f("tried to forward though signing bind"); 428 return -1; 429 } 430 if (permitted_by_dest_constraints(fromkey, hks->key, id, 431 test_user, hp) != 0) 432 return -1; 433 fromkey = hks->key; 434 } 435 /* 436 * Another special case: if the last bound session ID was for a 437 * forwarding, and this function is not being called to check a sign 438 * request (i.e. no 'user' supplied), then only permit the key if 439 * there is a permission that would allow it to be used at another 440 * destination. This hides keys that are allowed to be used to 441 * authenticate *to* a host but not permitted for *use* beyond it. 442 */ 443 hks = &e->session_ids[e->nsession_ids - 1]; 444 if (hks->forwarded && user == NULL && 445 permitted_by_dest_constraints(hks->key, NULL, id, 446 NULL, NULL) != 0) { 447 debug3_f("key permitted at host but not after"); 448 return -1; 449 } 450 451 /* success */ 452 return 0; 453 } 454 455 /* return matching private key for given public key */ 456 static Identity * 457 lookup_identity(struct sshkey *key) 458 { 459 Identity *id; 460 461 TAILQ_FOREACH(id, &idtab->idlist, next) { 462 if (sshkey_equal(key, id->key)) 463 return (id); 464 } 465 return (NULL); 466 } 467 468 /* Check confirmation of keysign request */ 469 static int 470 confirm_key(Identity *id, const char *extra) 471 { 472 char *p; 473 int ret = -1; 474 475 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 476 if (p != NULL && 477 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 478 id->comment, p, 479 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 480 ret = 0; 481 free(p); 482 483 return (ret); 484 } 485 486 static void 487 send_status(SocketEntry *e, int success) 488 { 489 int r; 490 491 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 492 (r = sshbuf_put_u8(e->output, success ? 493 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 494 fatal_fr(r, "compose"); 495 } 496 497 /* send list of supported public keys to 'client' */ 498 static void 499 process_request_identities(SocketEntry *e) 500 { 501 Identity *id; 502 struct sshbuf *msg, *keys; 503 int r; 504 u_int nentries = 0; 505 506 debug2_f("entering"); 507 508 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 509 fatal_f("sshbuf_new failed"); 510 TAILQ_FOREACH(id, &idtab->idlist, next) { 511 /* identity not visible, don't include in response */ 512 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 513 continue; 514 if ((r = sshkey_puts_opts(id->key, keys, 515 SSHKEY_SERIALIZE_INFO)) != 0 || 516 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 517 error_fr(r, "compose key/comment"); 518 continue; 519 } 520 nentries++; 521 } 522 debug2_f("replying with %u allowed of %u available keys", 523 nentries, idtab->nentries); 524 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 525 (r = sshbuf_put_u32(msg, nentries)) != 0 || 526 (r = sshbuf_putb(msg, keys)) != 0) 527 fatal_fr(r, "compose"); 528 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 529 fatal_fr(r, "enqueue"); 530 sshbuf_free(msg); 531 sshbuf_free(keys); 532 } 533 534 535 static char * 536 agent_decode_alg(struct sshkey *key, u_int flags) 537 { 538 if (key->type == KEY_RSA) { 539 if (flags & SSH_AGENT_RSA_SHA2_256) 540 return "rsa-sha2-256"; 541 else if (flags & SSH_AGENT_RSA_SHA2_512) 542 return "rsa-sha2-512"; 543 } else if (key->type == KEY_RSA_CERT) { 544 if (flags & SSH_AGENT_RSA_SHA2_256) 545 return "rsa-sha2-256-cert-v01@openssh.com"; 546 else if (flags & SSH_AGENT_RSA_SHA2_512) 547 return "rsa-sha2-512-cert-v01@openssh.com"; 548 } 549 return NULL; 550 } 551 552 /* 553 * Attempt to parse the contents of a buffer as a SSH publickey userauth 554 * request, checking its contents for consistency and matching the embedded 555 * key against the one that is being used for signing. 556 * Note: does not modify msg buffer. 557 * Optionally extract the username, session ID and/or hostkey from the request. 558 */ 559 static int 560 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 561 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 562 { 563 struct sshbuf *b = NULL, *sess_id = NULL; 564 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 565 int r; 566 u_char t, sig_follows; 567 struct sshkey *mkey = NULL, *hostkey = NULL; 568 569 if (userp != NULL) 570 *userp = NULL; 571 if (sess_idp != NULL) 572 *sess_idp = NULL; 573 if (hostkeyp != NULL) 574 *hostkeyp = NULL; 575 if ((b = sshbuf_fromb(msg)) == NULL) 576 fatal_f("sshbuf_fromb"); 577 578 /* SSH userauth request */ 579 if ((r = sshbuf_froms(b, &sess_id)) != 0) 580 goto out; 581 if (sshbuf_len(sess_id) == 0) { 582 r = SSH_ERR_INVALID_FORMAT; 583 goto out; 584 } 585 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 586 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 587 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 588 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 589 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 590 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 591 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 592 goto out; 593 if (t != SSH2_MSG_USERAUTH_REQUEST || 594 sig_follows != 1 || 595 strcmp(service, "ssh-connection") != 0 || 596 !sshkey_equal(expected_key, mkey) || 597 sshkey_type_from_name(pkalg) != expected_key->type) { 598 r = SSH_ERR_INVALID_FORMAT; 599 goto out; 600 } 601 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 602 if ((r = sshkey_froms(b, &hostkey)) != 0) 603 goto out; 604 } else if (strcmp(method, "publickey") != 0) { 605 r = SSH_ERR_INVALID_FORMAT; 606 goto out; 607 } 608 if (sshbuf_len(b) != 0) { 609 r = SSH_ERR_INVALID_FORMAT; 610 goto out; 611 } 612 /* success */ 613 r = 0; 614 debug3_f("well formed userauth"); 615 if (userp != NULL) { 616 *userp = user; 617 user = NULL; 618 } 619 if (sess_idp != NULL) { 620 *sess_idp = sess_id; 621 sess_id = NULL; 622 } 623 if (hostkeyp != NULL) { 624 *hostkeyp = hostkey; 625 hostkey = NULL; 626 } 627 out: 628 sshbuf_free(b); 629 sshbuf_free(sess_id); 630 free(user); 631 free(service); 632 free(method); 633 free(pkalg); 634 sshkey_free(mkey); 635 sshkey_free(hostkey); 636 return r; 637 } 638 639 /* 640 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 641 * Note: does not modify buffer. 642 */ 643 static int 644 parse_sshsig_request(struct sshbuf *msg) 645 { 646 int r; 647 struct sshbuf *b; 648 649 if ((b = sshbuf_fromb(msg)) == NULL) 650 fatal_f("sshbuf_fromb"); 651 652 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 653 (r = sshbuf_consume(b, 6)) != 0 || 654 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 655 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 656 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 657 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 658 goto out; 659 if (sshbuf_len(b) != 0) { 660 r = SSH_ERR_INVALID_FORMAT; 661 goto out; 662 } 663 /* success */ 664 r = 0; 665 out: 666 sshbuf_free(b); 667 return r; 668 } 669 670 /* 671 * This function inspects a message to be signed by a FIDO key that has a 672 * web-like application string (i.e. one that does not begin with "ssh:". 673 * It checks that the message is one of those expected for SSH operations 674 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 675 * for the web. 676 */ 677 static int 678 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 679 { 680 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 681 debug_f("signed data matches public key userauth request"); 682 return 1; 683 } 684 if (parse_sshsig_request(data) == 0) { 685 debug_f("signed data matches SSHSIG signature request"); 686 return 1; 687 } 688 689 /* XXX check CA signature operation */ 690 691 error("web-origin key attempting to sign non-SSH message"); 692 return 0; 693 } 694 695 static int 696 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 697 { 698 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 699 return SSH_ERR_INVALID_ARGUMENT; 700 if (sshbuf_len(a) != sshbuf_len(b)) 701 return SSH_ERR_INVALID_FORMAT; 702 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 703 return SSH_ERR_INVALID_FORMAT; 704 return 0; 705 } 706 707 /* ssh2 only */ 708 static void 709 process_sign_request2(SocketEntry *e) 710 { 711 u_char *signature = NULL; 712 size_t slen = 0; 713 u_int compat = 0, flags; 714 int r, ok = -1, retried = 0; 715 char *fp = NULL, *pin = NULL, *prompt = NULL; 716 char *user = NULL, *sig_dest = NULL; 717 const char *fwd_host = NULL, *dest_host = NULL; 718 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 719 struct sshkey *key = NULL, *hostkey = NULL; 720 struct identity *id; 721 struct notifier_ctx *notifier = NULL; 722 723 debug_f("entering"); 724 725 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 726 fatal_f("sshbuf_new failed"); 727 if ((r = sshkey_froms(e->request, &key)) != 0 || 728 (r = sshbuf_get_stringb(e->request, data)) != 0 || 729 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 730 error_fr(r, "parse"); 731 goto send; 732 } 733 734 if ((id = lookup_identity(key)) == NULL) { 735 verbose_f("%s key not found", sshkey_type(key)); 736 goto send; 737 } 738 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 739 SSH_FP_DEFAULT)) == NULL) 740 fatal_f("fingerprint failed"); 741 742 if (id->ndest_constraints != 0) { 743 if (e->nsession_ids == 0) { 744 logit_f("refusing use of destination-constrained key " 745 "to sign on unbound connection"); 746 goto send; 747 } 748 if (parse_userauth_request(data, key, &user, &sid, 749 &hostkey) != 0) { 750 logit_f("refusing use of destination-constrained key " 751 "to sign an unidentified signature"); 752 goto send; 753 } 754 /* XXX logspam */ 755 debug_f("user=%s", user); 756 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 757 goto send; 758 /* XXX display fwd_host/dest_host in askpass UI */ 759 /* 760 * Ensure that the session ID is the most recent one 761 * registered on the socket - it should have been bound by 762 * ssh immediately before userauth. 763 */ 764 if (buf_equal(sid, 765 e->session_ids[e->nsession_ids - 1].sid) != 0) { 766 error_f("unexpected session ID (%zu listed) on " 767 "signature request for target user %s with " 768 "key %s %s", e->nsession_ids, user, 769 sshkey_type(id->key), fp); 770 goto send; 771 } 772 /* 773 * Ensure that the hostkey embedded in the signature matches 774 * the one most recently bound to the socket. An exception is 775 * made for the initial forwarding hop. 776 */ 777 if (e->nsession_ids > 1 && hostkey == NULL) { 778 error_f("refusing use of destination-constrained key: " 779 "no hostkey recorded in signature for forwarded " 780 "connection"); 781 goto send; 782 } 783 if (hostkey != NULL && !sshkey_equal(hostkey, 784 e->session_ids[e->nsession_ids - 1].key)) { 785 error_f("refusing use of destination-constrained key: " 786 "mismatch between hostkey in request and most " 787 "recently bound session"); 788 goto send; 789 } 790 xasprintf(&sig_dest, "public key authentication request for " 791 "user \"%s\" to listed host", user); 792 } 793 if (id->confirm && confirm_key(id, sig_dest) != 0) { 794 verbose_f("user refused key"); 795 goto send; 796 } 797 if (sshkey_is_sk(id->key)) { 798 if (restrict_websafe && 799 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 800 !check_websafe_message_contents(key, data)) { 801 /* error already logged */ 802 goto send; 803 } 804 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 805 notifier = notify_start(0, 806 "Confirm user presence for key %s %s%s%s", 807 sshkey_type(id->key), fp, 808 sig_dest == NULL ? "" : "\n", 809 sig_dest == NULL ? "" : sig_dest); 810 } 811 } 812 retry_pin: 813 if ((r = sshkey_sign(id->key, &signature, &slen, 814 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 815 id->sk_provider, pin, compat)) != 0) { 816 debug_fr(r, "sshkey_sign"); 817 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 818 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 819 notify_complete(notifier, NULL); 820 notifier = NULL; 821 /* XXX include sig_dest */ 822 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 823 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 824 " and confirm user presence " : " ", 825 sshkey_type(id->key), fp); 826 pin = read_passphrase(prompt, RP_USE_ASKPASS); 827 retried = 1; 828 goto retry_pin; 829 } 830 error_fr(r, "sshkey_sign"); 831 goto send; 832 } 833 /* Success */ 834 ok = 0; 835 send: 836 debug_f("good signature"); 837 notify_complete(notifier, "User presence confirmed"); 838 839 if (ok == 0) { 840 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 841 (r = sshbuf_put_string(msg, signature, slen)) != 0) 842 fatal_fr(r, "compose"); 843 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 844 fatal_fr(r, "compose failure"); 845 846 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 847 fatal_fr(r, "enqueue"); 848 849 sshbuf_free(sid); 850 sshbuf_free(data); 851 sshbuf_free(msg); 852 sshkey_free(key); 853 sshkey_free(hostkey); 854 free(fp); 855 free(signature); 856 free(sig_dest); 857 free(user); 858 free(prompt); 859 if (pin != NULL) 860 freezero(pin, strlen(pin)); 861 } 862 863 /* shared */ 864 static void 865 process_remove_identity(SocketEntry *e) 866 { 867 int r, success = 0; 868 struct sshkey *key = NULL; 869 Identity *id; 870 871 debug2_f("entering"); 872 if ((r = sshkey_froms(e->request, &key)) != 0) { 873 error_fr(r, "parse key"); 874 goto done; 875 } 876 if ((id = lookup_identity(key)) == NULL) { 877 debug_f("key not found"); 878 goto done; 879 } 880 /* identity not visible, cannot be removed */ 881 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 882 goto done; /* error already logged */ 883 /* We have this key, free it. */ 884 if (idtab->nentries < 1) 885 fatal_f("internal error: nentries %d", idtab->nentries); 886 TAILQ_REMOVE(&idtab->idlist, id, next); 887 free_identity(id); 888 idtab->nentries--; 889 success = 1; 890 done: 891 sshkey_free(key); 892 send_status(e, success); 893 } 894 895 static void 896 process_remove_all_identities(SocketEntry *e) 897 { 898 Identity *id; 899 900 debug2_f("entering"); 901 /* Loop over all identities and clear the keys. */ 902 for (id = TAILQ_FIRST(&idtab->idlist); id; 903 id = TAILQ_FIRST(&idtab->idlist)) { 904 TAILQ_REMOVE(&idtab->idlist, id, next); 905 free_identity(id); 906 } 907 908 /* Mark that there are no identities. */ 909 idtab->nentries = 0; 910 911 /* Send success. */ 912 send_status(e, 1); 913 } 914 915 /* removes expired keys and returns number of seconds until the next expiry */ 916 static time_t 917 reaper(void) 918 { 919 time_t deadline = 0, now = monotime(); 920 Identity *id, *nxt; 921 922 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 923 nxt = TAILQ_NEXT(id, next); 924 if (id->death == 0) 925 continue; 926 if (now >= id->death) { 927 debug("expiring key '%s'", id->comment); 928 TAILQ_REMOVE(&idtab->idlist, id, next); 929 free_identity(id); 930 idtab->nentries--; 931 } else 932 deadline = (deadline == 0) ? id->death : 933 MINIMUM(deadline, id->death); 934 } 935 if (deadline == 0 || deadline <= now) 936 return 0; 937 else 938 return (deadline - now); 939 } 940 941 static int 942 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 943 { 944 u_char key_is_ca; 945 size_t elen = 0; 946 int r; 947 struct sshkey *k = NULL; 948 char *fp; 949 950 memset(dch, '\0', sizeof(*dch)); 951 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 952 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 953 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 954 error_fr(r, "parse"); 955 goto out; 956 } 957 if (elen != 0) { 958 error_f("unsupported extensions (len %zu)", elen); 959 r = SSH_ERR_FEATURE_UNSUPPORTED; 960 goto out; 961 } 962 if (*dch->hostname == '\0') { 963 free(dch->hostname); 964 dch->hostname = NULL; 965 } 966 if (*dch->user == '\0') { 967 free(dch->user); 968 dch->user = NULL; 969 } 970 while (sshbuf_len(b) != 0) { 971 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 972 dch->nkeys + 1, sizeof(*dch->keys)); 973 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 974 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 975 if ((r = sshkey_froms(b, &k)) != 0 || 976 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 977 goto out; 978 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 979 SSH_FP_DEFAULT)) == NULL) 980 fatal_f("fingerprint failed"); 981 debug3_f("%s%s%s: adding %skey %s %s", 982 dch->user == NULL ? "" : dch->user, 983 dch->user == NULL ? "" : "@", 984 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 985 free(fp); 986 dch->keys[dch->nkeys] = k; 987 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 988 dch->nkeys++; 989 k = NULL; /* transferred */ 990 } 991 /* success */ 992 r = 0; 993 out: 994 sshkey_free(k); 995 return r; 996 } 997 998 static int 999 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1000 { 1001 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1002 int r; 1003 size_t elen = 0; 1004 1005 debug3_f("entering"); 1006 1007 memset(dc, '\0', sizeof(*dc)); 1008 if ((r = sshbuf_froms(m, &b)) != 0 || 1009 (r = sshbuf_froms(b, &frombuf)) != 0 || 1010 (r = sshbuf_froms(b, &tobuf)) != 0 || 1011 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1012 error_fr(r, "parse"); 1013 goto out; 1014 } 1015 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1016 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1017 goto out; /* already logged */ 1018 if (elen != 0) { 1019 error_f("unsupported extensions (len %zu)", elen); 1020 r = SSH_ERR_FEATURE_UNSUPPORTED; 1021 goto out; 1022 } 1023 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1024 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1025 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1026 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1027 /* check consistency */ 1028 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1029 dc->from.user != NULL) { 1030 error_f("inconsistent \"from\" specification"); 1031 r = SSH_ERR_INVALID_FORMAT; 1032 goto out; 1033 } 1034 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1035 error_f("incomplete \"to\" specification"); 1036 r = SSH_ERR_INVALID_FORMAT; 1037 goto out; 1038 } 1039 /* success */ 1040 r = 0; 1041 out: 1042 sshbuf_free(b); 1043 sshbuf_free(frombuf); 1044 sshbuf_free(tobuf); 1045 return r; 1046 } 1047 1048 static int 1049 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1050 struct dest_constraint **dcsp, size_t *ndcsp) 1051 { 1052 char *ext_name = NULL; 1053 int r; 1054 struct sshbuf *b = NULL; 1055 1056 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1057 error_fr(r, "parse constraint extension"); 1058 goto out; 1059 } 1060 debug_f("constraint ext %s", ext_name); 1061 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1062 if (sk_providerp == NULL) { 1063 error_f("%s not valid here", ext_name); 1064 r = SSH_ERR_INVALID_FORMAT; 1065 goto out; 1066 } 1067 if (*sk_providerp != NULL) { 1068 error_f("%s already set", ext_name); 1069 r = SSH_ERR_INVALID_FORMAT; 1070 goto out; 1071 } 1072 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1073 error_fr(r, "parse %s", ext_name); 1074 goto out; 1075 } 1076 } else if (strcmp(ext_name, 1077 "restrict-destination-v00@openssh.com") == 0) { 1078 if (*dcsp != NULL) { 1079 error_f("%s already set", ext_name); 1080 goto out; 1081 } 1082 if ((r = sshbuf_froms(m, &b)) != 0) { 1083 error_fr(r, "parse %s outer", ext_name); 1084 goto out; 1085 } 1086 while (sshbuf_len(b) != 0) { 1087 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1088 error_f("too many %s constraints", ext_name); 1089 goto out; 1090 } 1091 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1092 sizeof(**dcsp)); 1093 if ((r = parse_dest_constraint(b, 1094 *dcsp + (*ndcsp)++)) != 0) 1095 goto out; /* error already logged */ 1096 } 1097 } else { 1098 error_f("unsupported constraint \"%s\"", ext_name); 1099 r = SSH_ERR_FEATURE_UNSUPPORTED; 1100 goto out; 1101 } 1102 /* success */ 1103 r = 0; 1104 out: 1105 free(ext_name); 1106 sshbuf_free(b); 1107 return r; 1108 } 1109 1110 static int 1111 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1112 u_int *secondsp, int *confirmp, char **sk_providerp, 1113 struct dest_constraint **dcsp, size_t *ndcsp) 1114 { 1115 u_char ctype; 1116 int r; 1117 u_int seconds, maxsign = 0; 1118 1119 while (sshbuf_len(m)) { 1120 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1121 error_fr(r, "parse constraint type"); 1122 goto out; 1123 } 1124 switch (ctype) { 1125 case SSH_AGENT_CONSTRAIN_LIFETIME: 1126 if (*deathp != 0) { 1127 error_f("lifetime already set"); 1128 r = SSH_ERR_INVALID_FORMAT; 1129 goto out; 1130 } 1131 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1132 error_fr(r, "parse lifetime constraint"); 1133 goto out; 1134 } 1135 *deathp = monotime() + seconds; 1136 *secondsp = seconds; 1137 break; 1138 case SSH_AGENT_CONSTRAIN_CONFIRM: 1139 if (*confirmp != 0) { 1140 error_f("confirm already set"); 1141 r = SSH_ERR_INVALID_FORMAT; 1142 goto out; 1143 } 1144 *confirmp = 1; 1145 break; 1146 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1147 if (k == NULL) { 1148 error_f("maxsign not valid here"); 1149 r = SSH_ERR_INVALID_FORMAT; 1150 goto out; 1151 } 1152 if (maxsign != 0) { 1153 error_f("maxsign already set"); 1154 r = SSH_ERR_INVALID_FORMAT; 1155 goto out; 1156 } 1157 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1158 error_fr(r, "parse maxsign constraint"); 1159 goto out; 1160 } 1161 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1162 error_fr(r, "enable maxsign"); 1163 goto out; 1164 } 1165 break; 1166 case SSH_AGENT_CONSTRAIN_EXTENSION: 1167 if ((r = parse_key_constraint_extension(m, 1168 sk_providerp, dcsp, ndcsp)) != 0) 1169 goto out; /* error already logged */ 1170 break; 1171 default: 1172 error_f("Unknown constraint %d", ctype); 1173 r = SSH_ERR_FEATURE_UNSUPPORTED; 1174 goto out; 1175 } 1176 } 1177 /* success */ 1178 r = 0; 1179 out: 1180 return r; 1181 } 1182 1183 static void 1184 process_add_identity(SocketEntry *e) 1185 { 1186 Identity *id; 1187 int success = 0, confirm = 0; 1188 char *fp, *comment = NULL, *sk_provider = NULL; 1189 char canonical_provider[PATH_MAX]; 1190 time_t death = 0; 1191 u_int seconds = 0; 1192 struct dest_constraint *dest_constraints = NULL; 1193 size_t ndest_constraints = 0; 1194 struct sshkey *k = NULL; 1195 int r = SSH_ERR_INTERNAL_ERROR; 1196 1197 debug2_f("entering"); 1198 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1199 k == NULL || 1200 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1201 error_fr(r, "parse"); 1202 goto out; 1203 } 1204 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1205 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1206 error_f("failed to parse constraints"); 1207 sshbuf_reset(e->request); 1208 goto out; 1209 } 1210 1211 if (sk_provider != NULL) { 1212 if (!sshkey_is_sk(k)) { 1213 error("Cannot add provider: %s is not an " 1214 "authenticator-hosted key", sshkey_type(k)); 1215 goto out; 1216 } 1217 if (strcasecmp(sk_provider, "internal") == 0) { 1218 debug_f("internal provider"); 1219 } else { 1220 if (realpath(sk_provider, canonical_provider) == NULL) { 1221 verbose("failed provider \"%.100s\": " 1222 "realpath: %s", sk_provider, 1223 strerror(errno)); 1224 goto out; 1225 } 1226 free(sk_provider); 1227 sk_provider = xstrdup(canonical_provider); 1228 if (match_pattern_list(sk_provider, 1229 allowed_providers, 0) != 1) { 1230 error("Refusing add key: " 1231 "provider %s not allowed", sk_provider); 1232 goto out; 1233 } 1234 } 1235 } 1236 if ((r = sshkey_shield_private(k)) != 0) { 1237 error_fr(r, "shield private"); 1238 goto out; 1239 } 1240 if (lifetime && !death) 1241 death = monotime() + lifetime; 1242 if ((id = lookup_identity(k)) == NULL) { 1243 id = xcalloc(1, sizeof(Identity)); 1244 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1245 /* Increment the number of identities. */ 1246 idtab->nentries++; 1247 } else { 1248 /* identity not visible, do not update */ 1249 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1250 goto out; /* error already logged */ 1251 /* key state might have been updated */ 1252 sshkey_free(id->key); 1253 free(id->comment); 1254 free(id->sk_provider); 1255 free_dest_constraints(id->dest_constraints, 1256 id->ndest_constraints); 1257 } 1258 /* success */ 1259 id->key = k; 1260 id->comment = comment; 1261 id->death = death; 1262 id->confirm = confirm; 1263 id->sk_provider = sk_provider; 1264 id->dest_constraints = dest_constraints; 1265 id->ndest_constraints = ndest_constraints; 1266 1267 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1268 SSH_FP_DEFAULT)) == NULL) 1269 fatal_f("sshkey_fingerprint failed"); 1270 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1271 "(provider: %s) (destination constraints: %zu)", 1272 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1273 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1274 free(fp); 1275 /* transferred */ 1276 k = NULL; 1277 comment = NULL; 1278 sk_provider = NULL; 1279 dest_constraints = NULL; 1280 ndest_constraints = 0; 1281 success = 1; 1282 out: 1283 free(sk_provider); 1284 free(comment); 1285 sshkey_free(k); 1286 free_dest_constraints(dest_constraints, ndest_constraints); 1287 send_status(e, success); 1288 } 1289 1290 /* XXX todo: encrypt sensitive data with passphrase */ 1291 static void 1292 process_lock_agent(SocketEntry *e, int lock) 1293 { 1294 int r, success = 0, delay; 1295 char *passwd; 1296 u_char passwdhash[LOCK_SIZE]; 1297 static u_int fail_count = 0; 1298 size_t pwlen; 1299 1300 debug2_f("entering"); 1301 /* 1302 * This is deliberately fatal: the user has requested that we lock, 1303 * but we can't parse their request properly. The only safe thing to 1304 * do is abort. 1305 */ 1306 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1307 fatal_fr(r, "parse"); 1308 if (pwlen == 0) { 1309 debug("empty password not supported"); 1310 } else if (locked && !lock) { 1311 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1312 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1313 fatal("bcrypt_pbkdf"); 1314 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1315 debug("agent unlocked"); 1316 locked = 0; 1317 fail_count = 0; 1318 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1319 success = 1; 1320 } else { 1321 /* delay in 0.1s increments up to 10s */ 1322 if (fail_count < 100) 1323 fail_count++; 1324 delay = 100000 * fail_count; 1325 debug("unlock failed, delaying %0.1lf seconds", 1326 (double)delay/1000000); 1327 usleep(delay); 1328 } 1329 explicit_bzero(passwdhash, sizeof(passwdhash)); 1330 } else if (!locked && lock) { 1331 debug("agent locked"); 1332 locked = 1; 1333 arc4random_buf(lock_salt, sizeof(lock_salt)); 1334 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1335 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1336 fatal("bcrypt_pbkdf"); 1337 success = 1; 1338 } 1339 freezero(passwd, pwlen); 1340 send_status(e, success); 1341 } 1342 1343 static void 1344 no_identities(SocketEntry *e) 1345 { 1346 struct sshbuf *msg; 1347 int r; 1348 1349 if ((msg = sshbuf_new()) == NULL) 1350 fatal_f("sshbuf_new failed"); 1351 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1352 (r = sshbuf_put_u32(msg, 0)) != 0 || 1353 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1354 fatal_fr(r, "compose"); 1355 sshbuf_free(msg); 1356 } 1357 1358 #ifdef ENABLE_PKCS11 1359 static void 1360 process_add_smartcard_key(SocketEntry *e) 1361 { 1362 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1363 char **comments = NULL; 1364 int r, i, count = 0, success = 0, confirm = 0; 1365 u_int seconds = 0; 1366 time_t death = 0; 1367 struct sshkey **keys = NULL, *k; 1368 Identity *id; 1369 struct dest_constraint *dest_constraints = NULL; 1370 size_t ndest_constraints = 0; 1371 1372 debug2_f("entering"); 1373 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1374 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1375 error_fr(r, "parse"); 1376 goto send; 1377 } 1378 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1379 NULL, &dest_constraints, &ndest_constraints) != 0) { 1380 error_f("failed to parse constraints"); 1381 goto send; 1382 } 1383 if (realpath(provider, canonical_provider) == NULL) { 1384 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1385 provider, strerror(errno)); 1386 goto send; 1387 } 1388 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1389 verbose("refusing PKCS#11 add of \"%.100s\": " 1390 "provider not allowed", canonical_provider); 1391 goto send; 1392 } 1393 debug_f("add %.100s", canonical_provider); 1394 if (lifetime && !death) 1395 death = monotime() + lifetime; 1396 1397 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1398 for (i = 0; i < count; i++) { 1399 k = keys[i]; 1400 if (lookup_identity(k) == NULL) { 1401 id = xcalloc(1, sizeof(Identity)); 1402 id->key = k; 1403 keys[i] = NULL; /* transferred */ 1404 id->provider = xstrdup(canonical_provider); 1405 if (*comments[i] != '\0') { 1406 id->comment = comments[i]; 1407 comments[i] = NULL; /* transferred */ 1408 } else { 1409 id->comment = xstrdup(canonical_provider); 1410 } 1411 id->death = death; 1412 id->confirm = confirm; 1413 id->dest_constraints = dest_constraints; 1414 id->ndest_constraints = ndest_constraints; 1415 dest_constraints = NULL; /* transferred */ 1416 ndest_constraints = 0; 1417 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1418 idtab->nentries++; 1419 success = 1; 1420 } 1421 /* XXX update constraints for existing keys */ 1422 sshkey_free(keys[i]); 1423 free(comments[i]); 1424 } 1425 send: 1426 free(pin); 1427 free(provider); 1428 free(keys); 1429 free(comments); 1430 free_dest_constraints(dest_constraints, ndest_constraints); 1431 send_status(e, success); 1432 } 1433 1434 static void 1435 process_remove_smartcard_key(SocketEntry *e) 1436 { 1437 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1438 int r, success = 0; 1439 Identity *id, *nxt; 1440 1441 debug2_f("entering"); 1442 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1443 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1444 error_fr(r, "parse"); 1445 goto send; 1446 } 1447 free(pin); 1448 1449 if (realpath(provider, canonical_provider) == NULL) { 1450 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1451 provider, strerror(errno)); 1452 goto send; 1453 } 1454 1455 debug_f("remove %.100s", canonical_provider); 1456 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1457 nxt = TAILQ_NEXT(id, next); 1458 /* Skip file--based keys */ 1459 if (id->provider == NULL) 1460 continue; 1461 if (!strcmp(canonical_provider, id->provider)) { 1462 TAILQ_REMOVE(&idtab->idlist, id, next); 1463 free_identity(id); 1464 idtab->nentries--; 1465 } 1466 } 1467 if (pkcs11_del_provider(canonical_provider) == 0) 1468 success = 1; 1469 else 1470 error_f("pkcs11_del_provider failed"); 1471 send: 1472 free(provider); 1473 send_status(e, success); 1474 } 1475 #endif /* ENABLE_PKCS11 */ 1476 1477 static int 1478 process_ext_session_bind(SocketEntry *e) 1479 { 1480 int r, sid_match, key_match; 1481 struct sshkey *key = NULL; 1482 struct sshbuf *sid = NULL, *sig = NULL; 1483 char *fp = NULL; 1484 size_t i; 1485 u_char fwd = 0; 1486 1487 debug2_f("entering"); 1488 if ((r = sshkey_froms(e->request, &key)) != 0 || 1489 (r = sshbuf_froms(e->request, &sid)) != 0 || 1490 (r = sshbuf_froms(e->request, &sig)) != 0 || 1491 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1492 error_fr(r, "parse"); 1493 goto out; 1494 } 1495 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1496 SSH_FP_DEFAULT)) == NULL) 1497 fatal_f("fingerprint failed"); 1498 /* check signature with hostkey on session ID */ 1499 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1500 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1501 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1502 goto out; 1503 } 1504 /* check whether sid/key already recorded */ 1505 for (i = 0; i < e->nsession_ids; i++) { 1506 if (!e->session_ids[i].forwarded) { 1507 error_f("attempt to bind session ID to socket " 1508 "previously bound for authentication attempt"); 1509 r = -1; 1510 goto out; 1511 } 1512 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1513 key_match = sshkey_equal(key, e->session_ids[i].key); 1514 if (sid_match && key_match) { 1515 debug_f("session ID already recorded for %s %s", 1516 sshkey_type(key), fp); 1517 r = 0; 1518 goto out; 1519 } else if (sid_match) { 1520 error_f("session ID recorded against different key " 1521 "for %s %s", sshkey_type(key), fp); 1522 r = -1; 1523 goto out; 1524 } 1525 /* 1526 * new sid with previously-seen key can happen, e.g. multiple 1527 * connections to the same host. 1528 */ 1529 } 1530 /* record new key/sid */ 1531 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1532 error_f("too many session IDs recorded"); 1533 goto out; 1534 } 1535 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1536 e->nsession_ids + 1, sizeof(*e->session_ids)); 1537 i = e->nsession_ids++; 1538 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1539 AGENT_MAX_SESSION_IDS); 1540 e->session_ids[i].key = key; 1541 e->session_ids[i].forwarded = fwd != 0; 1542 key = NULL; /* transferred */ 1543 /* can't transfer sid; it's refcounted and scoped to request's life */ 1544 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1545 fatal_f("sshbuf_new"); 1546 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1547 fatal_fr(r, "sshbuf_putb session ID"); 1548 /* success */ 1549 r = 0; 1550 out: 1551 free(fp); 1552 sshkey_free(key); 1553 sshbuf_free(sid); 1554 sshbuf_free(sig); 1555 return r == 0 ? 1 : 0; 1556 } 1557 1558 static void 1559 process_extension(SocketEntry *e) 1560 { 1561 int r, success = 0; 1562 char *name; 1563 1564 debug2_f("entering"); 1565 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1566 error_fr(r, "parse"); 1567 goto send; 1568 } 1569 if (strcmp(name, "session-bind@openssh.com") == 0) 1570 success = process_ext_session_bind(e); 1571 else 1572 debug_f("unsupported extension \"%s\"", name); 1573 free(name); 1574 send: 1575 send_status(e, success); 1576 } 1577 /* 1578 * dispatch incoming message. 1579 * returns 1 on success, 0 for incomplete messages or -1 on error. 1580 */ 1581 static int 1582 process_message(u_int socknum) 1583 { 1584 u_int msg_len; 1585 u_char type; 1586 const u_char *cp; 1587 int r; 1588 SocketEntry *e; 1589 1590 if (socknum >= sockets_alloc) 1591 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1592 e = &sockets[socknum]; 1593 1594 if (sshbuf_len(e->input) < 5) 1595 return 0; /* Incomplete message header. */ 1596 cp = sshbuf_ptr(e->input); 1597 msg_len = PEEK_U32(cp); 1598 if (msg_len > AGENT_MAX_LEN) { 1599 debug_f("socket %u (fd=%d) message too long %u > %u", 1600 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1601 return -1; 1602 } 1603 if (sshbuf_len(e->input) < msg_len + 4) 1604 return 0; /* Incomplete message body. */ 1605 1606 /* move the current input to e->request */ 1607 sshbuf_reset(e->request); 1608 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1609 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1610 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1611 r == SSH_ERR_STRING_TOO_LARGE) { 1612 error_fr(r, "parse"); 1613 return -1; 1614 } 1615 fatal_fr(r, "parse"); 1616 } 1617 1618 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1619 1620 /* check whether agent is locked */ 1621 if (locked && type != SSH_AGENTC_UNLOCK) { 1622 sshbuf_reset(e->request); 1623 switch (type) { 1624 case SSH2_AGENTC_REQUEST_IDENTITIES: 1625 /* send empty lists */ 1626 no_identities(e); 1627 break; 1628 default: 1629 /* send a fail message for all other request types */ 1630 send_status(e, 0); 1631 } 1632 return 1; 1633 } 1634 1635 switch (type) { 1636 case SSH_AGENTC_LOCK: 1637 case SSH_AGENTC_UNLOCK: 1638 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1639 break; 1640 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1641 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1642 break; 1643 /* ssh2 */ 1644 case SSH2_AGENTC_SIGN_REQUEST: 1645 process_sign_request2(e); 1646 break; 1647 case SSH2_AGENTC_REQUEST_IDENTITIES: 1648 process_request_identities(e); 1649 break; 1650 case SSH2_AGENTC_ADD_IDENTITY: 1651 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1652 process_add_identity(e); 1653 break; 1654 case SSH2_AGENTC_REMOVE_IDENTITY: 1655 process_remove_identity(e); 1656 break; 1657 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1658 process_remove_all_identities(e); 1659 break; 1660 #ifdef ENABLE_PKCS11 1661 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1662 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1663 process_add_smartcard_key(e); 1664 break; 1665 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1666 process_remove_smartcard_key(e); 1667 break; 1668 #endif /* ENABLE_PKCS11 */ 1669 case SSH_AGENTC_EXTENSION: 1670 process_extension(e); 1671 break; 1672 default: 1673 /* Unknown message. Respond with failure. */ 1674 error("Unknown message %d", type); 1675 sshbuf_reset(e->request); 1676 send_status(e, 0); 1677 break; 1678 } 1679 return 1; 1680 } 1681 1682 static void 1683 new_socket(sock_type type, int fd) 1684 { 1685 u_int i, old_alloc, new_alloc; 1686 1687 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1688 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1689 set_nonblock(fd); 1690 1691 if (fd > max_fd) 1692 max_fd = fd; 1693 1694 for (i = 0; i < sockets_alloc; i++) 1695 if (sockets[i].type == AUTH_UNUSED) { 1696 sockets[i].fd = fd; 1697 if ((sockets[i].input = sshbuf_new()) == NULL || 1698 (sockets[i].output = sshbuf_new()) == NULL || 1699 (sockets[i].request = sshbuf_new()) == NULL) 1700 fatal_f("sshbuf_new failed"); 1701 sockets[i].type = type; 1702 return; 1703 } 1704 old_alloc = sockets_alloc; 1705 new_alloc = sockets_alloc + 10; 1706 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1707 sizeof(sockets[0])); 1708 for (i = old_alloc; i < new_alloc; i++) 1709 sockets[i].type = AUTH_UNUSED; 1710 sockets_alloc = new_alloc; 1711 sockets[old_alloc].fd = fd; 1712 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1713 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1714 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1715 fatal_f("sshbuf_new failed"); 1716 sockets[old_alloc].type = type; 1717 } 1718 1719 static int 1720 handle_socket_read(u_int socknum) 1721 { 1722 struct sockaddr_un sunaddr; 1723 socklen_t slen; 1724 uid_t euid; 1725 gid_t egid; 1726 int fd; 1727 1728 slen = sizeof(sunaddr); 1729 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1730 if (fd == -1) { 1731 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1732 return -1; 1733 } 1734 if (getpeereid(fd, &euid, &egid) == -1) { 1735 error("getpeereid %d failed: %s", fd, strerror(errno)); 1736 close(fd); 1737 return -1; 1738 } 1739 if ((euid != 0) && (getuid() != euid)) { 1740 error("uid mismatch: peer euid %u != uid %u", 1741 (u_int) euid, (u_int) getuid()); 1742 close(fd); 1743 return -1; 1744 } 1745 new_socket(AUTH_CONNECTION, fd); 1746 return 0; 1747 } 1748 1749 static int 1750 handle_conn_read(u_int socknum) 1751 { 1752 char buf[AGENT_RBUF_LEN]; 1753 ssize_t len; 1754 int r; 1755 1756 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1757 if (len == -1) { 1758 if (errno == EAGAIN || errno == EINTR) 1759 return 0; 1760 error_f("read error on socket %u (fd %d): %s", 1761 socknum, sockets[socknum].fd, strerror(errno)); 1762 } 1763 return -1; 1764 } 1765 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1766 fatal_fr(r, "compose"); 1767 explicit_bzero(buf, sizeof(buf)); 1768 for (;;) { 1769 if ((r = process_message(socknum)) == -1) 1770 return -1; 1771 else if (r == 0) 1772 break; 1773 } 1774 return 0; 1775 } 1776 1777 static int 1778 handle_conn_write(u_int socknum) 1779 { 1780 ssize_t len; 1781 int r; 1782 1783 if (sshbuf_len(sockets[socknum].output) == 0) 1784 return 0; /* shouldn't happen */ 1785 if ((len = write(sockets[socknum].fd, 1786 sshbuf_ptr(sockets[socknum].output), 1787 sshbuf_len(sockets[socknum].output))) <= 0) { 1788 if (len == -1) { 1789 if (errno == EAGAIN || errno == EINTR) 1790 return 0; 1791 error_f("read error on socket %u (fd %d): %s", 1792 socknum, sockets[socknum].fd, strerror(errno)); 1793 } 1794 return -1; 1795 } 1796 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1797 fatal_fr(r, "consume"); 1798 return 0; 1799 } 1800 1801 static void 1802 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1803 { 1804 size_t i; 1805 u_int socknum, activefds = npfd; 1806 1807 for (i = 0; i < npfd; i++) { 1808 if (pfd[i].revents == 0) 1809 continue; 1810 /* Find sockets entry */ 1811 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1812 if (sockets[socknum].type != AUTH_SOCKET && 1813 sockets[socknum].type != AUTH_CONNECTION) 1814 continue; 1815 if (pfd[i].fd == sockets[socknum].fd) 1816 break; 1817 } 1818 if (socknum >= sockets_alloc) { 1819 error_f("no socket for fd %d", pfd[i].fd); 1820 continue; 1821 } 1822 /* Process events */ 1823 switch (sockets[socknum].type) { 1824 case AUTH_SOCKET: 1825 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1826 break; 1827 if (npfd > maxfds) { 1828 debug3("out of fds (active %u >= limit %u); " 1829 "skipping accept", activefds, maxfds); 1830 break; 1831 } 1832 if (handle_socket_read(socknum) == 0) 1833 activefds++; 1834 break; 1835 case AUTH_CONNECTION: 1836 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1837 handle_conn_read(socknum) != 0) 1838 goto close_sock; 1839 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1840 handle_conn_write(socknum) != 0) { 1841 close_sock: 1842 if (activefds == 0) 1843 fatal("activefds == 0 at close_sock"); 1844 close_socket(&sockets[socknum]); 1845 activefds--; 1846 break; 1847 } 1848 break; 1849 default: 1850 break; 1851 } 1852 } 1853 } 1854 1855 static int 1856 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1857 { 1858 struct pollfd *pfd = *pfdp; 1859 size_t i, j, npfd = 0; 1860 time_t deadline; 1861 int r; 1862 1863 /* Count active sockets */ 1864 for (i = 0; i < sockets_alloc; i++) { 1865 switch (sockets[i].type) { 1866 case AUTH_SOCKET: 1867 case AUTH_CONNECTION: 1868 npfd++; 1869 break; 1870 case AUTH_UNUSED: 1871 break; 1872 default: 1873 fatal("Unknown socket type %d", sockets[i].type); 1874 break; 1875 } 1876 } 1877 if (npfd != *npfdp && 1878 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1879 fatal_f("recallocarray failed"); 1880 *pfdp = pfd; 1881 *npfdp = npfd; 1882 1883 for (i = j = 0; i < sockets_alloc; i++) { 1884 switch (sockets[i].type) { 1885 case AUTH_SOCKET: 1886 if (npfd > maxfds) { 1887 debug3("out of fds (active %zu >= limit %u); " 1888 "skipping arming listener", npfd, maxfds); 1889 break; 1890 } 1891 pfd[j].fd = sockets[i].fd; 1892 pfd[j].revents = 0; 1893 pfd[j].events = POLLIN; 1894 j++; 1895 break; 1896 case AUTH_CONNECTION: 1897 pfd[j].fd = sockets[i].fd; 1898 pfd[j].revents = 0; 1899 /* 1900 * Only prepare to read if we can handle a full-size 1901 * input read buffer and enqueue a max size reply.. 1902 */ 1903 if ((r = sshbuf_check_reserve(sockets[i].input, 1904 AGENT_RBUF_LEN)) == 0 && 1905 (r = sshbuf_check_reserve(sockets[i].output, 1906 AGENT_MAX_LEN)) == 0) 1907 pfd[j].events = POLLIN; 1908 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1909 fatal_fr(r, "reserve"); 1910 if (sshbuf_len(sockets[i].output) > 0) 1911 pfd[j].events |= POLLOUT; 1912 j++; 1913 break; 1914 default: 1915 break; 1916 } 1917 } 1918 deadline = reaper(); 1919 if (parent_alive_interval != 0) 1920 deadline = (deadline == 0) ? parent_alive_interval : 1921 MINIMUM(deadline, parent_alive_interval); 1922 if (deadline == 0) { 1923 *timeoutp = -1; /* INFTIM */ 1924 } else { 1925 if (deadline > INT_MAX / 1000) 1926 *timeoutp = INT_MAX / 1000; 1927 else 1928 *timeoutp = deadline * 1000; 1929 } 1930 return (1); 1931 } 1932 1933 static void 1934 cleanup_socket(void) 1935 { 1936 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1937 return; 1938 debug_f("cleanup"); 1939 if (socket_name[0]) 1940 unlink(socket_name); 1941 if (socket_dir[0]) 1942 rmdir(socket_dir); 1943 } 1944 1945 void 1946 cleanup_exit(int i) 1947 { 1948 cleanup_socket(); 1949 _exit(i); 1950 } 1951 1952 /*ARGSUSED*/ 1953 static void 1954 cleanup_handler(int sig) 1955 { 1956 cleanup_socket(); 1957 #ifdef ENABLE_PKCS11 1958 pkcs11_terminate(); 1959 #endif 1960 _exit(2); 1961 } 1962 1963 static void 1964 check_parent_exists(void) 1965 { 1966 /* 1967 * If our parent has exited then getppid() will return (pid_t)1, 1968 * so testing for that should be safe. 1969 */ 1970 if (parent_pid != -1 && getppid() != parent_pid) { 1971 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1972 cleanup_socket(); 1973 _exit(2); 1974 } 1975 } 1976 1977 static void 1978 usage(void) 1979 { 1980 fprintf(stderr, 1981 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1982 " [-O option] [-P allowed_providers] [-t life]\n" 1983 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 1984 " [-P allowed_providers] [-t life] command [arg ...]\n" 1985 " ssh-agent [-c | -s] -k\n"); 1986 exit(1); 1987 } 1988 1989 int 1990 main(int ac, char **av) 1991 { 1992 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1993 int sock, ch, result, saved_errno; 1994 char *shell, *format, *pidstr, *agentsocket = NULL; 1995 struct rlimit rlim; 1996 extern int optind; 1997 extern char *optarg; 1998 pid_t pid; 1999 char pidstrbuf[1 + 3 * sizeof pid]; 2000 size_t len; 2001 mode_t prev_mask; 2002 int timeout = -1; /* INFTIM */ 2003 struct pollfd *pfd = NULL; 2004 size_t npfd = 0; 2005 u_int maxfds; 2006 2007 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2008 sanitise_stdfd(); 2009 2010 /* drop */ 2011 setegid(getgid()); 2012 setgid(getgid()); 2013 2014 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2015 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2016 2017 #ifdef WITH_OPENSSL 2018 OpenSSL_add_all_algorithms(); 2019 #endif 2020 2021 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2022 switch (ch) { 2023 case 'E': 2024 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2025 if (fingerprint_hash == -1) 2026 fatal("Invalid hash algorithm \"%s\"", optarg); 2027 break; 2028 case 'c': 2029 if (s_flag) 2030 usage(); 2031 c_flag++; 2032 break; 2033 case 'k': 2034 k_flag++; 2035 break; 2036 case 'O': 2037 if (strcmp(optarg, "no-restrict-websafe") == 0) 2038 restrict_websafe = 0; 2039 else 2040 fatal("Unknown -O option"); 2041 break; 2042 case 'P': 2043 if (allowed_providers != NULL) 2044 fatal("-P option already specified"); 2045 allowed_providers = xstrdup(optarg); 2046 break; 2047 case 's': 2048 if (c_flag) 2049 usage(); 2050 s_flag++; 2051 break; 2052 case 'd': 2053 if (d_flag || D_flag) 2054 usage(); 2055 d_flag++; 2056 break; 2057 case 'D': 2058 if (d_flag || D_flag) 2059 usage(); 2060 D_flag++; 2061 break; 2062 case 'a': 2063 agentsocket = optarg; 2064 break; 2065 case 't': 2066 if ((lifetime = convtime(optarg)) == -1) { 2067 fprintf(stderr, "Invalid lifetime\n"); 2068 usage(); 2069 } 2070 break; 2071 default: 2072 usage(); 2073 } 2074 } 2075 ac -= optind; 2076 av += optind; 2077 2078 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2079 usage(); 2080 2081 if (allowed_providers == NULL) 2082 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2083 2084 if (ac == 0 && !c_flag && !s_flag) { 2085 shell = getenv("SHELL"); 2086 if (shell != NULL && (len = strlen(shell)) > 2 && 2087 strncmp(shell + len - 3, "csh", 3) == 0) 2088 c_flag = 1; 2089 } 2090 if (k_flag) { 2091 const char *errstr = NULL; 2092 2093 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2094 if (pidstr == NULL) { 2095 fprintf(stderr, "%s not set, cannot kill agent\n", 2096 SSH_AGENTPID_ENV_NAME); 2097 exit(1); 2098 } 2099 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2100 if (errstr) { 2101 fprintf(stderr, 2102 "%s=\"%s\", which is not a good PID: %s\n", 2103 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2104 exit(1); 2105 } 2106 if (kill(pid, SIGTERM) == -1) { 2107 perror("kill"); 2108 exit(1); 2109 } 2110 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2111 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2112 printf(format, SSH_AGENTPID_ENV_NAME); 2113 printf("echo Agent pid %ld killed;\n", (long)pid); 2114 exit(0); 2115 } 2116 2117 /* 2118 * Minimum file descriptors: 2119 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2120 * a few spare for libc / stack protectors / sanitisers, etc. 2121 */ 2122 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2123 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2124 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2125 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2126 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2127 2128 parent_pid = getpid(); 2129 2130 if (agentsocket == NULL) { 2131 /* Create private directory for agent socket */ 2132 mktemp_proto(socket_dir, sizeof(socket_dir)); 2133 if (mkdtemp(socket_dir) == NULL) { 2134 perror("mkdtemp: private socket dir"); 2135 exit(1); 2136 } 2137 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2138 (long)parent_pid); 2139 } else { 2140 /* Try to use specified agent socket */ 2141 socket_dir[0] = '\0'; 2142 strlcpy(socket_name, agentsocket, sizeof socket_name); 2143 } 2144 2145 /* 2146 * Create socket early so it will exist before command gets run from 2147 * the parent. 2148 */ 2149 prev_mask = umask(0177); 2150 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2151 if (sock < 0) { 2152 /* XXX - unix_listener() calls error() not perror() */ 2153 *socket_name = '\0'; /* Don't unlink any existing file */ 2154 cleanup_exit(1); 2155 } 2156 umask(prev_mask); 2157 2158 /* 2159 * Fork, and have the parent execute the command, if any, or present 2160 * the socket data. The child continues as the authentication agent. 2161 */ 2162 if (D_flag || d_flag) { 2163 log_init(__progname, 2164 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2165 SYSLOG_FACILITY_AUTH, 1); 2166 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2167 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2168 SSH_AUTHSOCKET_ENV_NAME); 2169 printf("echo Agent pid %ld;\n", (long)parent_pid); 2170 fflush(stdout); 2171 goto skip; 2172 } 2173 pid = fork(); 2174 if (pid == -1) { 2175 perror("fork"); 2176 cleanup_exit(1); 2177 } 2178 if (pid != 0) { /* Parent - execute the given command. */ 2179 close(sock); 2180 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2181 if (ac == 0) { 2182 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2183 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2184 SSH_AUTHSOCKET_ENV_NAME); 2185 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2186 SSH_AGENTPID_ENV_NAME); 2187 printf("echo Agent pid %ld;\n", (long)pid); 2188 exit(0); 2189 } 2190 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2191 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2192 perror("setenv"); 2193 exit(1); 2194 } 2195 execvp(av[0], av); 2196 perror(av[0]); 2197 exit(1); 2198 } 2199 /* child */ 2200 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2201 2202 if (setsid() == -1) { 2203 error("setsid: %s", strerror(errno)); 2204 cleanup_exit(1); 2205 } 2206 2207 (void)chdir("/"); 2208 if (stdfd_devnull(1, 1, 1) == -1) 2209 error_f("stdfd_devnull failed"); 2210 2211 /* deny core dumps, since memory contains unencrypted private keys */ 2212 rlim.rlim_cur = rlim.rlim_max = 0; 2213 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2214 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2215 cleanup_exit(1); 2216 } 2217 2218 skip: 2219 2220 cleanup_pid = getpid(); 2221 2222 #ifdef ENABLE_PKCS11 2223 pkcs11_init(0); 2224 #endif 2225 new_socket(AUTH_SOCKET, sock); 2226 if (ac > 0) 2227 parent_alive_interval = 10; 2228 idtab_init(); 2229 ssh_signal(SIGPIPE, SIG_IGN); 2230 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2231 ssh_signal(SIGHUP, cleanup_handler); 2232 ssh_signal(SIGTERM, cleanup_handler); 2233 2234 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2235 fatal("%s: pledge: %s", __progname, strerror(errno)); 2236 2237 while (1) { 2238 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2239 result = poll(pfd, npfd, timeout); 2240 saved_errno = errno; 2241 if (parent_alive_interval != 0) 2242 check_parent_exists(); 2243 (void) reaper(); /* remove expired keys */ 2244 if (result == -1) { 2245 if (saved_errno == EINTR) 2246 continue; 2247 fatal("poll: %s", strerror(saved_errno)); 2248 } else if (result > 0) 2249 after_poll(pfd, npfd, maxfds); 2250 } 2251 /* NOTREACHED */ 2252 } 2253