1 /* $OpenBSD: ssh-agent.c,v 1.285 2022/01/01 04:18:06 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include <sys/types.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/resource.h> 41 #include <sys/socket.h> 42 #include <sys/stat.h> 43 #include <sys/un.h> 44 #include <sys/wait.h> 45 46 #ifdef WITH_OPENSSL 47 #include <openssl/evp.h> 48 #endif 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <paths.h> 53 #include <poll.h> 54 #include <signal.h> 55 #include <stdlib.h> 56 #include <stdio.h> 57 #include <string.h> 58 #include <stdarg.h> 59 #include <limits.h> 60 #include <time.h> 61 #include <unistd.h> 62 #include <util.h> 63 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh2.h" 67 #include "sshbuf.h" 68 #include "sshkey.h" 69 #include "authfd.h" 70 #include "compat.h" 71 #include "log.h" 72 #include "misc.h" 73 #include "digest.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "msg.h" 77 #include "ssherr.h" 78 #include "pathnames.h" 79 #include "ssh-pkcs11.h" 80 #include "sk-api.h" 81 #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 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, dch->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, dch->hostname, 1, 291 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 292 debug_f("cert %s / hostname %s rejected: %s", 293 key->cert->key_id, dch->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; 714 char *fp = NULL, *user = NULL, *sig_dest = NULL; 715 const char *fwd_host = NULL, *dest_host = NULL; 716 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 717 struct sshkey *key = NULL, *hostkey = NULL; 718 struct identity *id; 719 struct notifier_ctx *notifier = NULL; 720 721 debug_f("entering"); 722 723 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 724 fatal_f("sshbuf_new failed"); 725 if ((r = sshkey_froms(e->request, &key)) != 0 || 726 (r = sshbuf_get_stringb(e->request, data)) != 0 || 727 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 728 error_fr(r, "parse"); 729 goto send; 730 } 731 732 if ((id = lookup_identity(key)) == NULL) { 733 verbose_f("%s key not found", sshkey_type(key)); 734 goto send; 735 } 736 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 737 SSH_FP_DEFAULT)) == NULL) 738 fatal_f("fingerprint failed"); 739 740 if (id->ndest_constraints != 0) { 741 if (e->nsession_ids == 0) { 742 logit_f("refusing use of destination-constrained key " 743 "to sign on unbound connection"); 744 goto send; 745 } 746 if (parse_userauth_request(data, key, &user, &sid, 747 &hostkey) != 0) { 748 logit_f("refusing use of destination-constrained key " 749 "to sign an unidentified signature"); 750 goto send; 751 } 752 /* XXX logspam */ 753 debug_f("user=%s", user); 754 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 755 goto send; 756 /* XXX display fwd_host/dest_host in askpass UI */ 757 /* 758 * Ensure that the session ID is the most recent one 759 * registered on the socket - it should have been bound by 760 * ssh immediately before userauth. 761 */ 762 if (buf_equal(sid, 763 e->session_ids[e->nsession_ids - 1].sid) != 0) { 764 error_f("unexpected session ID (%zu listed) on " 765 "signature request for target user %s with " 766 "key %s %s", e->nsession_ids, user, 767 sshkey_type(id->key), fp); 768 goto send; 769 } 770 /* 771 * Ensure that the hostkey embedded in the signature matches 772 * the one most recently bound to the socket. An exception is 773 * made for the initial forwarding hop. 774 */ 775 if (e->nsession_ids > 1 && hostkey == NULL) { 776 error_f("refusing use of destination-constrained key: " 777 "no hostkey recorded in signature for forwarded " 778 "connection"); 779 goto send; 780 } 781 if (hostkey != NULL && !sshkey_equal(hostkey, 782 e->session_ids[e->nsession_ids - 1].key)) { 783 error_f("refusing use of destination-constrained key: " 784 "mismatch between hostkey in request and most " 785 "recently bound session"); 786 goto send; 787 } 788 xasprintf(&sig_dest, "public key authentication request for " 789 "user \"%s\" to listed host", user); 790 } 791 if (id->confirm && confirm_key(id, sig_dest) != 0) { 792 verbose_f("user refused key"); 793 goto send; 794 } 795 if (sshkey_is_sk(id->key)) { 796 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 797 !check_websafe_message_contents(key, data)) { 798 /* error already logged */ 799 goto send; 800 } 801 if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 802 notifier = notify_start(0, 803 "Confirm user presence for key %s %s%s%s", 804 sshkey_type(id->key), fp, 805 sig_dest == NULL ? "" : "\n", 806 sig_dest == NULL ? "" : sig_dest); 807 } 808 } 809 /* XXX support PIN required FIDO keys */ 810 if ((r = sshkey_sign(id->key, &signature, &slen, 811 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 812 id->sk_provider, NULL, compat)) != 0) { 813 error_fr(r, "sshkey_sign"); 814 goto send; 815 } 816 /* Success */ 817 ok = 0; 818 send: 819 notify_complete(notifier, "User presence confirmed"); 820 821 if (ok == 0) { 822 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 823 (r = sshbuf_put_string(msg, signature, slen)) != 0) 824 fatal_fr(r, "compose"); 825 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 826 fatal_fr(r, "compose failure"); 827 828 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 829 fatal_fr(r, "enqueue"); 830 831 sshbuf_free(sid); 832 sshbuf_free(data); 833 sshbuf_free(msg); 834 sshkey_free(key); 835 sshkey_free(hostkey); 836 free(fp); 837 free(signature); 838 free(sig_dest); 839 free(user); 840 } 841 842 /* shared */ 843 static void 844 process_remove_identity(SocketEntry *e) 845 { 846 int r, success = 0; 847 struct sshkey *key = NULL; 848 Identity *id; 849 850 debug2_f("entering"); 851 if ((r = sshkey_froms(e->request, &key)) != 0) { 852 error_fr(r, "parse key"); 853 goto done; 854 } 855 if ((id = lookup_identity(key)) == NULL) { 856 debug_f("key not found"); 857 goto done; 858 } 859 /* identity not visible, cannot be removed */ 860 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 861 goto done; /* error already logged */ 862 /* We have this key, free it. */ 863 if (idtab->nentries < 1) 864 fatal_f("internal error: nentries %d", idtab->nentries); 865 TAILQ_REMOVE(&idtab->idlist, id, next); 866 free_identity(id); 867 idtab->nentries--; 868 success = 1; 869 done: 870 sshkey_free(key); 871 send_status(e, success); 872 } 873 874 static void 875 process_remove_all_identities(SocketEntry *e) 876 { 877 Identity *id; 878 879 debug2_f("entering"); 880 /* Loop over all identities and clear the keys. */ 881 for (id = TAILQ_FIRST(&idtab->idlist); id; 882 id = TAILQ_FIRST(&idtab->idlist)) { 883 TAILQ_REMOVE(&idtab->idlist, id, next); 884 free_identity(id); 885 } 886 887 /* Mark that there are no identities. */ 888 idtab->nentries = 0; 889 890 /* Send success. */ 891 send_status(e, 1); 892 } 893 894 /* removes expired keys and returns number of seconds until the next expiry */ 895 static time_t 896 reaper(void) 897 { 898 time_t deadline = 0, now = monotime(); 899 Identity *id, *nxt; 900 901 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 902 nxt = TAILQ_NEXT(id, next); 903 if (id->death == 0) 904 continue; 905 if (now >= id->death) { 906 debug("expiring key '%s'", id->comment); 907 TAILQ_REMOVE(&idtab->idlist, id, next); 908 free_identity(id); 909 idtab->nentries--; 910 } else 911 deadline = (deadline == 0) ? id->death : 912 MINIMUM(deadline, id->death); 913 } 914 if (deadline == 0 || deadline <= now) 915 return 0; 916 else 917 return (deadline - now); 918 } 919 920 static int 921 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 922 { 923 u_char key_is_ca; 924 size_t elen = 0; 925 int r; 926 struct sshkey *k = NULL; 927 char *fp; 928 929 memset(dch, '\0', sizeof(*dch)); 930 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 931 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 932 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 933 error_fr(r, "parse"); 934 goto out; 935 } 936 if (elen != 0) { 937 error_f("unsupported extensions (len %zu)", elen); 938 r = SSH_ERR_FEATURE_UNSUPPORTED; 939 goto out; 940 } 941 if (*dch->hostname == '\0') { 942 free(dch->hostname); 943 dch->hostname = NULL; 944 } 945 if (*dch->user == '\0') { 946 free(dch->user); 947 dch->user = NULL; 948 } 949 while (sshbuf_len(b) != 0) { 950 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 951 dch->nkeys + 1, sizeof(*dch->keys)); 952 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 953 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 954 if ((r = sshkey_froms(b, &k)) != 0 || 955 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 956 goto out; 957 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 958 SSH_FP_DEFAULT)) == NULL) 959 fatal_f("fingerprint failed"); 960 debug3_f("%s%s%s: adding %skey %s %s", 961 dch->user == NULL ? "" : dch->user, 962 dch->user == NULL ? "" : "@", 963 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 964 free(fp); 965 dch->keys[dch->nkeys] = k; 966 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 967 dch->nkeys++; 968 k = NULL; /* transferred */ 969 } 970 /* success */ 971 r = 0; 972 out: 973 sshkey_free(k); 974 return r; 975 } 976 977 static int 978 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 979 { 980 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 981 int r; 982 size_t elen = 0; 983 984 debug3_f("entering"); 985 986 memset(dc, '\0', sizeof(*dc)); 987 if ((r = sshbuf_froms(m, &b)) != 0 || 988 (r = sshbuf_froms(b, &frombuf)) != 0 || 989 (r = sshbuf_froms(b, &tobuf)) != 0 || 990 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 991 error_fr(r, "parse"); 992 goto out; 993 } 994 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 995 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 996 goto out; /* already logged */ 997 if (elen != 0) { 998 error_f("unsupported extensions (len %zu)", elen); 999 r = SSH_ERR_FEATURE_UNSUPPORTED; 1000 goto out; 1001 } 1002 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1003 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1004 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1005 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1006 /* check consistency */ 1007 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1008 dc->from.user != NULL) { 1009 error_f("inconsistent \"from\" specification"); 1010 r = SSH_ERR_INVALID_FORMAT; 1011 goto out; 1012 } 1013 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1014 error_f("incomplete \"to\" specification"); 1015 r = SSH_ERR_INVALID_FORMAT; 1016 goto out; 1017 } 1018 /* success */ 1019 r = 0; 1020 out: 1021 sshbuf_free(b); 1022 sshbuf_free(frombuf); 1023 sshbuf_free(tobuf); 1024 return r; 1025 } 1026 1027 static int 1028 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1029 struct dest_constraint **dcsp, size_t *ndcsp) 1030 { 1031 char *ext_name = NULL; 1032 int r; 1033 struct sshbuf *b = NULL; 1034 1035 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1036 error_fr(r, "parse constraint extension"); 1037 goto out; 1038 } 1039 debug_f("constraint ext %s", ext_name); 1040 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1041 if (sk_providerp == NULL) { 1042 error_f("%s not valid here", ext_name); 1043 r = SSH_ERR_INVALID_FORMAT; 1044 goto out; 1045 } 1046 if (*sk_providerp != NULL) { 1047 error_f("%s already set", ext_name); 1048 r = SSH_ERR_INVALID_FORMAT; 1049 goto out; 1050 } 1051 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1052 error_fr(r, "parse %s", ext_name); 1053 goto out; 1054 } 1055 } else if (strcmp(ext_name, 1056 "restrict-destination-v00@openssh.com") == 0) { 1057 if (*dcsp != NULL) { 1058 error_f("%s already set", ext_name); 1059 goto out; 1060 } 1061 if ((r = sshbuf_froms(m, &b)) != 0) { 1062 error_fr(r, "parse %s outer", ext_name); 1063 goto out; 1064 } 1065 while (sshbuf_len(b) != 0) { 1066 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1067 error_f("too many %s constraints", ext_name); 1068 goto out; 1069 } 1070 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1071 sizeof(**dcsp)); 1072 if ((r = parse_dest_constraint(b, 1073 *dcsp + (*ndcsp)++)) != 0) 1074 goto out; /* error already logged */ 1075 } 1076 } else { 1077 error_f("unsupported constraint \"%s\"", ext_name); 1078 r = SSH_ERR_FEATURE_UNSUPPORTED; 1079 goto out; 1080 } 1081 /* success */ 1082 r = 0; 1083 out: 1084 free(ext_name); 1085 sshbuf_free(b); 1086 return r; 1087 } 1088 1089 static int 1090 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1091 u_int *secondsp, int *confirmp, char **sk_providerp, 1092 struct dest_constraint **dcsp, size_t *ndcsp) 1093 { 1094 u_char ctype; 1095 int r; 1096 u_int seconds, maxsign = 0; 1097 1098 while (sshbuf_len(m)) { 1099 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1100 error_fr(r, "parse constraint type"); 1101 goto out; 1102 } 1103 switch (ctype) { 1104 case SSH_AGENT_CONSTRAIN_LIFETIME: 1105 if (*deathp != 0) { 1106 error_f("lifetime already set"); 1107 r = SSH_ERR_INVALID_FORMAT; 1108 goto out; 1109 } 1110 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1111 error_fr(r, "parse lifetime constraint"); 1112 goto out; 1113 } 1114 *deathp = monotime() + seconds; 1115 *secondsp = seconds; 1116 break; 1117 case SSH_AGENT_CONSTRAIN_CONFIRM: 1118 if (*confirmp != 0) { 1119 error_f("confirm already set"); 1120 r = SSH_ERR_INVALID_FORMAT; 1121 goto out; 1122 } 1123 *confirmp = 1; 1124 break; 1125 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1126 if (k == NULL) { 1127 error_f("maxsign not valid here"); 1128 r = SSH_ERR_INVALID_FORMAT; 1129 goto out; 1130 } 1131 if (maxsign != 0) { 1132 error_f("maxsign already set"); 1133 r = SSH_ERR_INVALID_FORMAT; 1134 goto out; 1135 } 1136 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1137 error_fr(r, "parse maxsign constraint"); 1138 goto out; 1139 } 1140 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1141 error_fr(r, "enable maxsign"); 1142 goto out; 1143 } 1144 break; 1145 case SSH_AGENT_CONSTRAIN_EXTENSION: 1146 if ((r = parse_key_constraint_extension(m, 1147 sk_providerp, dcsp, ndcsp)) != 0) 1148 goto out; /* error already logged */ 1149 break; 1150 default: 1151 error_f("Unknown constraint %d", ctype); 1152 r = SSH_ERR_FEATURE_UNSUPPORTED; 1153 goto out; 1154 } 1155 } 1156 /* success */ 1157 r = 0; 1158 out: 1159 return r; 1160 } 1161 1162 static void 1163 process_add_identity(SocketEntry *e) 1164 { 1165 Identity *id; 1166 int success = 0, confirm = 0; 1167 char *fp, *comment = NULL, *sk_provider = NULL; 1168 char canonical_provider[PATH_MAX]; 1169 time_t death = 0; 1170 u_int seconds = 0; 1171 struct dest_constraint *dest_constraints = NULL; 1172 size_t ndest_constraints = 0; 1173 struct sshkey *k = NULL; 1174 int r = SSH_ERR_INTERNAL_ERROR; 1175 1176 debug2_f("entering"); 1177 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1178 k == NULL || 1179 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1180 error_fr(r, "parse"); 1181 goto out; 1182 } 1183 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1184 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1185 error_f("failed to parse constraints"); 1186 sshbuf_reset(e->request); 1187 goto out; 1188 } 1189 1190 if (sk_provider != NULL) { 1191 if (!sshkey_is_sk(k)) { 1192 error("Cannot add provider: %s is not an " 1193 "authenticator-hosted key", sshkey_type(k)); 1194 goto out; 1195 } 1196 if (strcasecmp(sk_provider, "internal") == 0) { 1197 debug_f("internal provider"); 1198 } else { 1199 if (realpath(sk_provider, canonical_provider) == NULL) { 1200 verbose("failed provider \"%.100s\": " 1201 "realpath: %s", sk_provider, 1202 strerror(errno)); 1203 goto out; 1204 } 1205 free(sk_provider); 1206 sk_provider = xstrdup(canonical_provider); 1207 if (match_pattern_list(sk_provider, 1208 allowed_providers, 0) != 1) { 1209 error("Refusing add key: " 1210 "provider %s not allowed", sk_provider); 1211 goto out; 1212 } 1213 } 1214 } 1215 if ((r = sshkey_shield_private(k)) != 0) { 1216 error_fr(r, "shield private"); 1217 goto out; 1218 } 1219 if (lifetime && !death) 1220 death = monotime() + lifetime; 1221 if ((id = lookup_identity(k)) == NULL) { 1222 id = xcalloc(1, sizeof(Identity)); 1223 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1224 /* Increment the number of identities. */ 1225 idtab->nentries++; 1226 } else { 1227 /* identity not visible, do not update */ 1228 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1229 goto out; /* error already logged */ 1230 /* key state might have been updated */ 1231 sshkey_free(id->key); 1232 free(id->comment); 1233 free(id->sk_provider); 1234 free_dest_constraints(id->dest_constraints, 1235 id->ndest_constraints); 1236 } 1237 /* success */ 1238 id->key = k; 1239 id->comment = comment; 1240 id->death = death; 1241 id->confirm = confirm; 1242 id->sk_provider = sk_provider; 1243 id->dest_constraints = dest_constraints; 1244 id->ndest_constraints = ndest_constraints; 1245 1246 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1247 SSH_FP_DEFAULT)) == NULL) 1248 fatal_f("sshkey_fingerprint failed"); 1249 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1250 "(provider: %s) (destination constraints: %zu)", 1251 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1252 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1253 free(fp); 1254 /* transferred */ 1255 k = NULL; 1256 comment = NULL; 1257 sk_provider = NULL; 1258 dest_constraints = NULL; 1259 ndest_constraints = 0; 1260 success = 1; 1261 out: 1262 free(sk_provider); 1263 free(comment); 1264 sshkey_free(k); 1265 free_dest_constraints(dest_constraints, ndest_constraints); 1266 send_status(e, success); 1267 } 1268 1269 /* XXX todo: encrypt sensitive data with passphrase */ 1270 static void 1271 process_lock_agent(SocketEntry *e, int lock) 1272 { 1273 int r, success = 0, delay; 1274 char *passwd; 1275 u_char passwdhash[LOCK_SIZE]; 1276 static u_int fail_count = 0; 1277 size_t pwlen; 1278 1279 debug2_f("entering"); 1280 /* 1281 * This is deliberately fatal: the user has requested that we lock, 1282 * but we can't parse their request properly. The only safe thing to 1283 * do is abort. 1284 */ 1285 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1286 fatal_fr(r, "parse"); 1287 if (pwlen == 0) { 1288 debug("empty password not supported"); 1289 } else if (locked && !lock) { 1290 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1291 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1292 fatal("bcrypt_pbkdf"); 1293 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1294 debug("agent unlocked"); 1295 locked = 0; 1296 fail_count = 0; 1297 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1298 success = 1; 1299 } else { 1300 /* delay in 0.1s increments up to 10s */ 1301 if (fail_count < 100) 1302 fail_count++; 1303 delay = 100000 * fail_count; 1304 debug("unlock failed, delaying %0.1lf seconds", 1305 (double)delay/1000000); 1306 usleep(delay); 1307 } 1308 explicit_bzero(passwdhash, sizeof(passwdhash)); 1309 } else if (!locked && lock) { 1310 debug("agent locked"); 1311 locked = 1; 1312 arc4random_buf(lock_salt, sizeof(lock_salt)); 1313 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1314 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1315 fatal("bcrypt_pbkdf"); 1316 success = 1; 1317 } 1318 freezero(passwd, pwlen); 1319 send_status(e, success); 1320 } 1321 1322 static void 1323 no_identities(SocketEntry *e) 1324 { 1325 struct sshbuf *msg; 1326 int r; 1327 1328 if ((msg = sshbuf_new()) == NULL) 1329 fatal_f("sshbuf_new failed"); 1330 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1331 (r = sshbuf_put_u32(msg, 0)) != 0 || 1332 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1333 fatal_fr(r, "compose"); 1334 sshbuf_free(msg); 1335 } 1336 1337 #ifdef ENABLE_PKCS11 1338 static void 1339 process_add_smartcard_key(SocketEntry *e) 1340 { 1341 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1342 char **comments = NULL; 1343 int r, i, count = 0, success = 0, confirm = 0; 1344 u_int seconds = 0; 1345 time_t death = 0; 1346 struct sshkey **keys = NULL, *k; 1347 Identity *id; 1348 struct dest_constraint *dest_constraints = NULL; 1349 size_t ndest_constraints = 0; 1350 1351 debug2_f("entering"); 1352 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1353 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1354 error_fr(r, "parse"); 1355 goto send; 1356 } 1357 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1358 NULL, &dest_constraints, &ndest_constraints) != 0) { 1359 error_f("failed to parse constraints"); 1360 goto send; 1361 } 1362 if (realpath(provider, canonical_provider) == NULL) { 1363 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1364 provider, strerror(errno)); 1365 goto send; 1366 } 1367 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1368 verbose("refusing PKCS#11 add of \"%.100s\": " 1369 "provider not allowed", canonical_provider); 1370 goto send; 1371 } 1372 debug_f("add %.100s", canonical_provider); 1373 if (lifetime && !death) 1374 death = monotime() + lifetime; 1375 1376 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1377 for (i = 0; i < count; i++) { 1378 k = keys[i]; 1379 if (lookup_identity(k) == NULL) { 1380 id = xcalloc(1, sizeof(Identity)); 1381 id->key = k; 1382 keys[i] = NULL; /* transferred */ 1383 id->provider = xstrdup(canonical_provider); 1384 if (*comments[i] != '\0') { 1385 id->comment = comments[i]; 1386 comments[i] = NULL; /* transferred */ 1387 } else { 1388 id->comment = xstrdup(canonical_provider); 1389 } 1390 id->death = death; 1391 id->confirm = confirm; 1392 id->dest_constraints = dest_constraints; 1393 id->ndest_constraints = ndest_constraints; 1394 dest_constraints = NULL; /* transferred */ 1395 ndest_constraints = 0; 1396 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1397 idtab->nentries++; 1398 success = 1; 1399 } 1400 /* XXX update constraints for existing keys */ 1401 sshkey_free(keys[i]); 1402 free(comments[i]); 1403 } 1404 send: 1405 free(pin); 1406 free(provider); 1407 free(keys); 1408 free(comments); 1409 free_dest_constraints(dest_constraints, ndest_constraints); 1410 send_status(e, success); 1411 } 1412 1413 static void 1414 process_remove_smartcard_key(SocketEntry *e) 1415 { 1416 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1417 int r, success = 0; 1418 Identity *id, *nxt; 1419 1420 debug2_f("entering"); 1421 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1422 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1423 error_fr(r, "parse"); 1424 goto send; 1425 } 1426 free(pin); 1427 1428 if (realpath(provider, canonical_provider) == NULL) { 1429 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1430 provider, strerror(errno)); 1431 goto send; 1432 } 1433 1434 debug_f("remove %.100s", canonical_provider); 1435 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1436 nxt = TAILQ_NEXT(id, next); 1437 /* Skip file--based keys */ 1438 if (id->provider == NULL) 1439 continue; 1440 if (!strcmp(canonical_provider, id->provider)) { 1441 TAILQ_REMOVE(&idtab->idlist, id, next); 1442 free_identity(id); 1443 idtab->nentries--; 1444 } 1445 } 1446 if (pkcs11_del_provider(canonical_provider) == 0) 1447 success = 1; 1448 else 1449 error_f("pkcs11_del_provider failed"); 1450 send: 1451 free(provider); 1452 send_status(e, success); 1453 } 1454 #endif /* ENABLE_PKCS11 */ 1455 1456 static int 1457 process_ext_session_bind(SocketEntry *e) 1458 { 1459 int r, sid_match, key_match; 1460 struct sshkey *key = NULL; 1461 struct sshbuf *sid = NULL, *sig = NULL; 1462 char *fp = NULL; 1463 size_t i; 1464 u_char fwd = 0; 1465 1466 debug2_f("entering"); 1467 if ((r = sshkey_froms(e->request, &key)) != 0 || 1468 (r = sshbuf_froms(e->request, &sid)) != 0 || 1469 (r = sshbuf_froms(e->request, &sig)) != 0 || 1470 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1471 error_fr(r, "parse"); 1472 goto out; 1473 } 1474 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1475 SSH_FP_DEFAULT)) == NULL) 1476 fatal_f("fingerprint failed"); 1477 /* check signature with hostkey on session ID */ 1478 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1479 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1480 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1481 goto out; 1482 } 1483 /* check whether sid/key already recorded */ 1484 for (i = 0; i < e->nsession_ids; i++) { 1485 if (!e->session_ids[i].forwarded) { 1486 error_f("attempt to bind session ID to socket " 1487 "previously bound for authentication attempt"); 1488 r = -1; 1489 goto out; 1490 } 1491 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1492 key_match = sshkey_equal(key, e->session_ids[i].key); 1493 if (sid_match && key_match) { 1494 debug_f("session ID already recorded for %s %s", 1495 sshkey_type(key), fp); 1496 r = 0; 1497 goto out; 1498 } else if (sid_match) { 1499 error_f("session ID recorded against different key " 1500 "for %s %s", sshkey_type(key), fp); 1501 r = -1; 1502 goto out; 1503 } 1504 /* 1505 * new sid with previously-seen key can happen, e.g. multiple 1506 * connections to the same host. 1507 */ 1508 } 1509 /* record new key/sid */ 1510 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1511 error_f("too many session IDs recorded"); 1512 goto out; 1513 } 1514 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1515 e->nsession_ids + 1, sizeof(*e->session_ids)); 1516 i = e->nsession_ids++; 1517 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1518 AGENT_MAX_SESSION_IDS); 1519 e->session_ids[i].key = key; 1520 e->session_ids[i].forwarded = fwd != 0; 1521 key = NULL; /* transferred */ 1522 /* can't transfer sid; it's refcounted and scoped to request's life */ 1523 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1524 fatal_f("sshbuf_new"); 1525 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1526 fatal_fr(r, "sshbuf_putb session ID"); 1527 /* success */ 1528 r = 0; 1529 out: 1530 sshkey_free(key); 1531 sshbuf_free(sid); 1532 sshbuf_free(sig); 1533 return r == 0 ? 1 : 0; 1534 } 1535 1536 static void 1537 process_extension(SocketEntry *e) 1538 { 1539 int r, success = 0; 1540 char *name; 1541 1542 debug2_f("entering"); 1543 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1544 error_fr(r, "parse"); 1545 goto send; 1546 } 1547 if (strcmp(name, "session-bind@openssh.com") == 0) 1548 success = process_ext_session_bind(e); 1549 else 1550 debug_f("unsupported extension \"%s\"", name); 1551 free(name); 1552 send: 1553 send_status(e, success); 1554 } 1555 /* 1556 * dispatch incoming message. 1557 * returns 1 on success, 0 for incomplete messages or -1 on error. 1558 */ 1559 static int 1560 process_message(u_int socknum) 1561 { 1562 u_int msg_len; 1563 u_char type; 1564 const u_char *cp; 1565 int r; 1566 SocketEntry *e; 1567 1568 if (socknum >= sockets_alloc) 1569 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1570 e = &sockets[socknum]; 1571 1572 if (sshbuf_len(e->input) < 5) 1573 return 0; /* Incomplete message header. */ 1574 cp = sshbuf_ptr(e->input); 1575 msg_len = PEEK_U32(cp); 1576 if (msg_len > AGENT_MAX_LEN) { 1577 debug_f("socket %u (fd=%d) message too long %u > %u", 1578 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1579 return -1; 1580 } 1581 if (sshbuf_len(e->input) < msg_len + 4) 1582 return 0; /* Incomplete message body. */ 1583 1584 /* move the current input to e->request */ 1585 sshbuf_reset(e->request); 1586 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1587 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1588 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1589 r == SSH_ERR_STRING_TOO_LARGE) { 1590 error_fr(r, "parse"); 1591 return -1; 1592 } 1593 fatal_fr(r, "parse"); 1594 } 1595 1596 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1597 1598 /* check whether agent is locked */ 1599 if (locked && type != SSH_AGENTC_UNLOCK) { 1600 sshbuf_reset(e->request); 1601 switch (type) { 1602 case SSH2_AGENTC_REQUEST_IDENTITIES: 1603 /* send empty lists */ 1604 no_identities(e); 1605 break; 1606 default: 1607 /* send a fail message for all other request types */ 1608 send_status(e, 0); 1609 } 1610 return 1; 1611 } 1612 1613 switch (type) { 1614 case SSH_AGENTC_LOCK: 1615 case SSH_AGENTC_UNLOCK: 1616 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1617 break; 1618 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1619 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1620 break; 1621 /* ssh2 */ 1622 case SSH2_AGENTC_SIGN_REQUEST: 1623 process_sign_request2(e); 1624 break; 1625 case SSH2_AGENTC_REQUEST_IDENTITIES: 1626 process_request_identities(e); 1627 break; 1628 case SSH2_AGENTC_ADD_IDENTITY: 1629 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1630 process_add_identity(e); 1631 break; 1632 case SSH2_AGENTC_REMOVE_IDENTITY: 1633 process_remove_identity(e); 1634 break; 1635 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1636 process_remove_all_identities(e); 1637 break; 1638 #ifdef ENABLE_PKCS11 1639 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1640 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1641 process_add_smartcard_key(e); 1642 break; 1643 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1644 process_remove_smartcard_key(e); 1645 break; 1646 #endif /* ENABLE_PKCS11 */ 1647 case SSH_AGENTC_EXTENSION: 1648 process_extension(e); 1649 break; 1650 default: 1651 /* Unknown message. Respond with failure. */ 1652 error("Unknown message %d", type); 1653 sshbuf_reset(e->request); 1654 send_status(e, 0); 1655 break; 1656 } 1657 return 1; 1658 } 1659 1660 static void 1661 new_socket(sock_type type, int fd) 1662 { 1663 u_int i, old_alloc, new_alloc; 1664 1665 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1666 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1667 set_nonblock(fd); 1668 1669 if (fd > max_fd) 1670 max_fd = fd; 1671 1672 for (i = 0; i < sockets_alloc; i++) 1673 if (sockets[i].type == AUTH_UNUSED) { 1674 sockets[i].fd = fd; 1675 if ((sockets[i].input = sshbuf_new()) == NULL || 1676 (sockets[i].output = sshbuf_new()) == NULL || 1677 (sockets[i].request = sshbuf_new()) == NULL) 1678 fatal_f("sshbuf_new failed"); 1679 sockets[i].type = type; 1680 return; 1681 } 1682 old_alloc = sockets_alloc; 1683 new_alloc = sockets_alloc + 10; 1684 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1685 sizeof(sockets[0])); 1686 for (i = old_alloc; i < new_alloc; i++) 1687 sockets[i].type = AUTH_UNUSED; 1688 sockets_alloc = new_alloc; 1689 sockets[old_alloc].fd = fd; 1690 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1691 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1692 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1693 fatal_f("sshbuf_new failed"); 1694 sockets[old_alloc].type = type; 1695 } 1696 1697 static int 1698 handle_socket_read(u_int socknum) 1699 { 1700 struct sockaddr_un sunaddr; 1701 socklen_t slen; 1702 uid_t euid; 1703 gid_t egid; 1704 int fd; 1705 1706 slen = sizeof(sunaddr); 1707 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1708 if (fd == -1) { 1709 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1710 return -1; 1711 } 1712 if (getpeereid(fd, &euid, &egid) == -1) { 1713 error("getpeereid %d failed: %s", fd, strerror(errno)); 1714 close(fd); 1715 return -1; 1716 } 1717 if ((euid != 0) && (getuid() != euid)) { 1718 error("uid mismatch: peer euid %u != uid %u", 1719 (u_int) euid, (u_int) getuid()); 1720 close(fd); 1721 return -1; 1722 } 1723 new_socket(AUTH_CONNECTION, fd); 1724 return 0; 1725 } 1726 1727 static int 1728 handle_conn_read(u_int socknum) 1729 { 1730 char buf[AGENT_RBUF_LEN]; 1731 ssize_t len; 1732 int r; 1733 1734 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1735 if (len == -1) { 1736 if (errno == EAGAIN || errno == EINTR) 1737 return 0; 1738 error_f("read error on socket %u (fd %d): %s", 1739 socknum, sockets[socknum].fd, strerror(errno)); 1740 } 1741 return -1; 1742 } 1743 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1744 fatal_fr(r, "compose"); 1745 explicit_bzero(buf, sizeof(buf)); 1746 for (;;) { 1747 if ((r = process_message(socknum)) == -1) 1748 return -1; 1749 else if (r == 0) 1750 break; 1751 } 1752 return 0; 1753 } 1754 1755 static int 1756 handle_conn_write(u_int socknum) 1757 { 1758 ssize_t len; 1759 int r; 1760 1761 if (sshbuf_len(sockets[socknum].output) == 0) 1762 return 0; /* shouldn't happen */ 1763 if ((len = write(sockets[socknum].fd, 1764 sshbuf_ptr(sockets[socknum].output), 1765 sshbuf_len(sockets[socknum].output))) <= 0) { 1766 if (len == -1) { 1767 if (errno == EAGAIN || errno == EINTR) 1768 return 0; 1769 error_f("read error on socket %u (fd %d): %s", 1770 socknum, sockets[socknum].fd, strerror(errno)); 1771 } 1772 return -1; 1773 } 1774 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1775 fatal_fr(r, "consume"); 1776 return 0; 1777 } 1778 1779 static void 1780 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1781 { 1782 size_t i; 1783 u_int socknum, activefds = npfd; 1784 1785 for (i = 0; i < npfd; i++) { 1786 if (pfd[i].revents == 0) 1787 continue; 1788 /* Find sockets entry */ 1789 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1790 if (sockets[socknum].type != AUTH_SOCKET && 1791 sockets[socknum].type != AUTH_CONNECTION) 1792 continue; 1793 if (pfd[i].fd == sockets[socknum].fd) 1794 break; 1795 } 1796 if (socknum >= sockets_alloc) { 1797 error_f("no socket for fd %d", pfd[i].fd); 1798 continue; 1799 } 1800 /* Process events */ 1801 switch (sockets[socknum].type) { 1802 case AUTH_SOCKET: 1803 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1804 break; 1805 if (npfd > maxfds) { 1806 debug3("out of fds (active %u >= limit %u); " 1807 "skipping accept", activefds, maxfds); 1808 break; 1809 } 1810 if (handle_socket_read(socknum) == 0) 1811 activefds++; 1812 break; 1813 case AUTH_CONNECTION: 1814 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1815 handle_conn_read(socknum) != 0) 1816 goto close_sock; 1817 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1818 handle_conn_write(socknum) != 0) { 1819 close_sock: 1820 if (activefds == 0) 1821 fatal("activefds == 0 at close_sock"); 1822 close_socket(&sockets[socknum]); 1823 activefds--; 1824 break; 1825 } 1826 break; 1827 default: 1828 break; 1829 } 1830 } 1831 } 1832 1833 static int 1834 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1835 { 1836 struct pollfd *pfd = *pfdp; 1837 size_t i, j, npfd = 0; 1838 time_t deadline; 1839 int r; 1840 1841 /* Count active sockets */ 1842 for (i = 0; i < sockets_alloc; i++) { 1843 switch (sockets[i].type) { 1844 case AUTH_SOCKET: 1845 case AUTH_CONNECTION: 1846 npfd++; 1847 break; 1848 case AUTH_UNUSED: 1849 break; 1850 default: 1851 fatal("Unknown socket type %d", sockets[i].type); 1852 break; 1853 } 1854 } 1855 if (npfd != *npfdp && 1856 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1857 fatal_f("recallocarray failed"); 1858 *pfdp = pfd; 1859 *npfdp = npfd; 1860 1861 for (i = j = 0; i < sockets_alloc; i++) { 1862 switch (sockets[i].type) { 1863 case AUTH_SOCKET: 1864 if (npfd > maxfds) { 1865 debug3("out of fds (active %zu >= limit %u); " 1866 "skipping arming listener", npfd, maxfds); 1867 break; 1868 } 1869 pfd[j].fd = sockets[i].fd; 1870 pfd[j].revents = 0; 1871 pfd[j].events = POLLIN; 1872 j++; 1873 break; 1874 case AUTH_CONNECTION: 1875 pfd[j].fd = sockets[i].fd; 1876 pfd[j].revents = 0; 1877 /* 1878 * Only prepare to read if we can handle a full-size 1879 * input read buffer and enqueue a max size reply.. 1880 */ 1881 if ((r = sshbuf_check_reserve(sockets[i].input, 1882 AGENT_RBUF_LEN)) == 0 && 1883 (r = sshbuf_check_reserve(sockets[i].output, 1884 AGENT_MAX_LEN)) == 0) 1885 pfd[j].events = POLLIN; 1886 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1887 fatal_fr(r, "reserve"); 1888 if (sshbuf_len(sockets[i].output) > 0) 1889 pfd[j].events |= POLLOUT; 1890 j++; 1891 break; 1892 default: 1893 break; 1894 } 1895 } 1896 deadline = reaper(); 1897 if (parent_alive_interval != 0) 1898 deadline = (deadline == 0) ? parent_alive_interval : 1899 MINIMUM(deadline, parent_alive_interval); 1900 if (deadline == 0) { 1901 *timeoutp = -1; /* INFTIM */ 1902 } else { 1903 if (deadline > INT_MAX / 1000) 1904 *timeoutp = INT_MAX / 1000; 1905 else 1906 *timeoutp = deadline * 1000; 1907 } 1908 return (1); 1909 } 1910 1911 static void 1912 cleanup_socket(void) 1913 { 1914 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1915 return; 1916 debug_f("cleanup"); 1917 if (socket_name[0]) 1918 unlink(socket_name); 1919 if (socket_dir[0]) 1920 rmdir(socket_dir); 1921 } 1922 1923 void 1924 cleanup_exit(int i) 1925 { 1926 cleanup_socket(); 1927 _exit(i); 1928 } 1929 1930 /*ARGSUSED*/ 1931 static void 1932 cleanup_handler(int sig) 1933 { 1934 cleanup_socket(); 1935 #ifdef ENABLE_PKCS11 1936 pkcs11_terminate(); 1937 #endif 1938 _exit(2); 1939 } 1940 1941 static void 1942 check_parent_exists(void) 1943 { 1944 /* 1945 * If our parent has exited then getppid() will return (pid_t)1, 1946 * so testing for that should be safe. 1947 */ 1948 if (parent_pid != -1 && getppid() != parent_pid) { 1949 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1950 cleanup_socket(); 1951 _exit(2); 1952 } 1953 } 1954 1955 static void 1956 usage(void) 1957 { 1958 fprintf(stderr, 1959 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1960 " [-P allowed_providers] [-t life]\n" 1961 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1962 " [-t life] command [arg ...]\n" 1963 " ssh-agent [-c | -s] -k\n"); 1964 exit(1); 1965 } 1966 1967 int 1968 main(int ac, char **av) 1969 { 1970 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 1971 int sock, ch, result, saved_errno; 1972 char *shell, *format, *pidstr, *agentsocket = NULL; 1973 struct rlimit rlim; 1974 extern int optind; 1975 extern char *optarg; 1976 pid_t pid; 1977 char pidstrbuf[1 + 3 * sizeof pid]; 1978 size_t len; 1979 mode_t prev_mask; 1980 int timeout = -1; /* INFTIM */ 1981 struct pollfd *pfd = NULL; 1982 size_t npfd = 0; 1983 u_int maxfds; 1984 1985 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1986 sanitise_stdfd(); 1987 1988 /* drop */ 1989 setegid(getgid()); 1990 setgid(getgid()); 1991 1992 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 1993 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 1994 1995 #ifdef WITH_OPENSSL 1996 OpenSSL_add_all_algorithms(); 1997 #endif 1998 1999 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2000 switch (ch) { 2001 case 'E': 2002 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2003 if (fingerprint_hash == -1) 2004 fatal("Invalid hash algorithm \"%s\"", optarg); 2005 break; 2006 case 'c': 2007 if (s_flag) 2008 usage(); 2009 c_flag++; 2010 break; 2011 case 'k': 2012 k_flag++; 2013 break; 2014 case 'O': 2015 if (strcmp(optarg, "no-restrict-websafe") == 0) 2016 restrict_websafe = 0; 2017 else 2018 fatal("Unknown -O option"); 2019 break; 2020 case 'P': 2021 if (allowed_providers != NULL) 2022 fatal("-P option already specified"); 2023 allowed_providers = xstrdup(optarg); 2024 break; 2025 case 's': 2026 if (c_flag) 2027 usage(); 2028 s_flag++; 2029 break; 2030 case 'd': 2031 if (d_flag || D_flag) 2032 usage(); 2033 d_flag++; 2034 break; 2035 case 'D': 2036 if (d_flag || D_flag) 2037 usage(); 2038 D_flag++; 2039 break; 2040 case 'a': 2041 agentsocket = optarg; 2042 break; 2043 case 't': 2044 if ((lifetime = convtime(optarg)) == -1) { 2045 fprintf(stderr, "Invalid lifetime\n"); 2046 usage(); 2047 } 2048 break; 2049 default: 2050 usage(); 2051 } 2052 } 2053 ac -= optind; 2054 av += optind; 2055 2056 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2057 usage(); 2058 2059 if (allowed_providers == NULL) 2060 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2061 2062 if (ac == 0 && !c_flag && !s_flag) { 2063 shell = getenv("SHELL"); 2064 if (shell != NULL && (len = strlen(shell)) > 2 && 2065 strncmp(shell + len - 3, "csh", 3) == 0) 2066 c_flag = 1; 2067 } 2068 if (k_flag) { 2069 const char *errstr = NULL; 2070 2071 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2072 if (pidstr == NULL) { 2073 fprintf(stderr, "%s not set, cannot kill agent\n", 2074 SSH_AGENTPID_ENV_NAME); 2075 exit(1); 2076 } 2077 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2078 if (errstr) { 2079 fprintf(stderr, 2080 "%s=\"%s\", which is not a good PID: %s\n", 2081 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2082 exit(1); 2083 } 2084 if (kill(pid, SIGTERM) == -1) { 2085 perror("kill"); 2086 exit(1); 2087 } 2088 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2089 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2090 printf(format, SSH_AGENTPID_ENV_NAME); 2091 printf("echo Agent pid %ld killed;\n", (long)pid); 2092 exit(0); 2093 } 2094 2095 /* 2096 * Minimum file descriptors: 2097 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2098 * a few spare for libc / stack protectors / sanitisers, etc. 2099 */ 2100 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2101 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2102 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2103 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2104 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2105 2106 parent_pid = getpid(); 2107 2108 if (agentsocket == NULL) { 2109 /* Create private directory for agent socket */ 2110 mktemp_proto(socket_dir, sizeof(socket_dir)); 2111 if (mkdtemp(socket_dir) == NULL) { 2112 perror("mkdtemp: private socket dir"); 2113 exit(1); 2114 } 2115 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2116 (long)parent_pid); 2117 } else { 2118 /* Try to use specified agent socket */ 2119 socket_dir[0] = '\0'; 2120 strlcpy(socket_name, agentsocket, sizeof socket_name); 2121 } 2122 2123 /* 2124 * Create socket early so it will exist before command gets run from 2125 * the parent. 2126 */ 2127 prev_mask = umask(0177); 2128 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2129 if (sock < 0) { 2130 /* XXX - unix_listener() calls error() not perror() */ 2131 *socket_name = '\0'; /* Don't unlink any existing file */ 2132 cleanup_exit(1); 2133 } 2134 umask(prev_mask); 2135 2136 /* 2137 * Fork, and have the parent execute the command, if any, or present 2138 * the socket data. The child continues as the authentication agent. 2139 */ 2140 if (D_flag || d_flag) { 2141 log_init(__progname, 2142 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2143 SYSLOG_FACILITY_AUTH, 1); 2144 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2145 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2146 SSH_AUTHSOCKET_ENV_NAME); 2147 printf("echo Agent pid %ld;\n", (long)parent_pid); 2148 fflush(stdout); 2149 goto skip; 2150 } 2151 pid = fork(); 2152 if (pid == -1) { 2153 perror("fork"); 2154 cleanup_exit(1); 2155 } 2156 if (pid != 0) { /* Parent - execute the given command. */ 2157 close(sock); 2158 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2159 if (ac == 0) { 2160 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2161 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2162 SSH_AUTHSOCKET_ENV_NAME); 2163 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2164 SSH_AGENTPID_ENV_NAME); 2165 printf("echo Agent pid %ld;\n", (long)pid); 2166 exit(0); 2167 } 2168 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2169 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2170 perror("setenv"); 2171 exit(1); 2172 } 2173 execvp(av[0], av); 2174 perror(av[0]); 2175 exit(1); 2176 } 2177 /* child */ 2178 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2179 2180 if (setsid() == -1) { 2181 error("setsid: %s", strerror(errno)); 2182 cleanup_exit(1); 2183 } 2184 2185 (void)chdir("/"); 2186 if (stdfd_devnull(1, 1, 1) == -1) 2187 error_f("stdfd_devnull failed"); 2188 2189 /* deny core dumps, since memory contains unencrypted private keys */ 2190 rlim.rlim_cur = rlim.rlim_max = 0; 2191 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2192 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2193 cleanup_exit(1); 2194 } 2195 2196 skip: 2197 2198 cleanup_pid = getpid(); 2199 2200 #ifdef ENABLE_PKCS11 2201 pkcs11_init(0); 2202 #endif 2203 new_socket(AUTH_SOCKET, sock); 2204 if (ac > 0) 2205 parent_alive_interval = 10; 2206 idtab_init(); 2207 ssh_signal(SIGPIPE, SIG_IGN); 2208 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2209 ssh_signal(SIGHUP, cleanup_handler); 2210 ssh_signal(SIGTERM, cleanup_handler); 2211 2212 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2213 fatal("%s: pledge: %s", __progname, strerror(errno)); 2214 2215 while (1) { 2216 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2217 result = poll(pfd, npfd, timeout); 2218 saved_errno = errno; 2219 if (parent_alive_interval != 0) 2220 check_parent_exists(); 2221 (void) reaper(); /* remove expired keys */ 2222 if (result == -1) { 2223 if (saved_errno == EINTR) 2224 continue; 2225 fatal("poll: %s", strerror(saved_errno)); 2226 } else if (result > 0) 2227 after_poll(pfd, npfd, maxfds); 2228 } 2229 /* NOTREACHED */ 2230 } 2231