1 /* $OpenBSD: ssh-agent.c,v 1.288 2022/04/29 03:13:32 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 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 (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 799 !check_websafe_message_contents(key, data)) { 800 /* error already logged */ 801 goto send; 802 } 803 if ((id->key->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) { 804 /* XXX include sig_dest */ 805 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 806 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 807 " and confirm user presence " : " ", 808 sshkey_type(id->key), fp); 809 pin = read_passphrase(prompt, RP_USE_ASKPASS); 810 free(prompt); 811 prompt = NULL; 812 } else if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 813 notifier = notify_start(0, 814 "Confirm user presence for key %s %s%s%s", 815 sshkey_type(id->key), fp, 816 sig_dest == NULL ? "" : "\n", 817 sig_dest == NULL ? "" : sig_dest); 818 } 819 } 820 retry_pin: 821 if ((r = sshkey_sign(id->key, &signature, &slen, 822 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 823 id->sk_provider, pin, compat)) != 0) { 824 debug_fr(r, "sshkey_sign"); 825 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 826 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 827 if (notifier) { 828 notify_complete(notifier, NULL); 829 notifier = NULL; 830 } 831 /* XXX include sig_dest */ 832 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 833 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 834 " and confirm user presence " : " ", 835 sshkey_type(id->key), fp); 836 pin = read_passphrase(prompt, RP_USE_ASKPASS); 837 retried = 1; 838 goto retry_pin; 839 } 840 error_fr(r, "sshkey_sign"); 841 goto send; 842 } 843 /* Success */ 844 ok = 0; 845 send: 846 notify_complete(notifier, "User presence confirmed"); 847 848 if (ok == 0) { 849 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 850 (r = sshbuf_put_string(msg, signature, slen)) != 0) 851 fatal_fr(r, "compose"); 852 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 853 fatal_fr(r, "compose failure"); 854 855 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 856 fatal_fr(r, "enqueue"); 857 858 sshbuf_free(sid); 859 sshbuf_free(data); 860 sshbuf_free(msg); 861 sshkey_free(key); 862 sshkey_free(hostkey); 863 free(fp); 864 free(signature); 865 free(sig_dest); 866 free(user); 867 free(prompt); 868 if (pin != NULL) 869 freezero(pin, strlen(pin)); 870 } 871 872 /* shared */ 873 static void 874 process_remove_identity(SocketEntry *e) 875 { 876 int r, success = 0; 877 struct sshkey *key = NULL; 878 Identity *id; 879 880 debug2_f("entering"); 881 if ((r = sshkey_froms(e->request, &key)) != 0) { 882 error_fr(r, "parse key"); 883 goto done; 884 } 885 if ((id = lookup_identity(key)) == NULL) { 886 debug_f("key not found"); 887 goto done; 888 } 889 /* identity not visible, cannot be removed */ 890 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 891 goto done; /* error already logged */ 892 /* We have this key, free it. */ 893 if (idtab->nentries < 1) 894 fatal_f("internal error: nentries %d", idtab->nentries); 895 TAILQ_REMOVE(&idtab->idlist, id, next); 896 free_identity(id); 897 idtab->nentries--; 898 success = 1; 899 done: 900 sshkey_free(key); 901 send_status(e, success); 902 } 903 904 static void 905 process_remove_all_identities(SocketEntry *e) 906 { 907 Identity *id; 908 909 debug2_f("entering"); 910 /* Loop over all identities and clear the keys. */ 911 for (id = TAILQ_FIRST(&idtab->idlist); id; 912 id = TAILQ_FIRST(&idtab->idlist)) { 913 TAILQ_REMOVE(&idtab->idlist, id, next); 914 free_identity(id); 915 } 916 917 /* Mark that there are no identities. */ 918 idtab->nentries = 0; 919 920 /* Send success. */ 921 send_status(e, 1); 922 } 923 924 /* removes expired keys and returns number of seconds until the next expiry */ 925 static time_t 926 reaper(void) 927 { 928 time_t deadline = 0, now = monotime(); 929 Identity *id, *nxt; 930 931 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 932 nxt = TAILQ_NEXT(id, next); 933 if (id->death == 0) 934 continue; 935 if (now >= id->death) { 936 debug("expiring key '%s'", id->comment); 937 TAILQ_REMOVE(&idtab->idlist, id, next); 938 free_identity(id); 939 idtab->nentries--; 940 } else 941 deadline = (deadline == 0) ? id->death : 942 MINIMUM(deadline, id->death); 943 } 944 if (deadline == 0 || deadline <= now) 945 return 0; 946 else 947 return (deadline - now); 948 } 949 950 static int 951 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 952 { 953 u_char key_is_ca; 954 size_t elen = 0; 955 int r; 956 struct sshkey *k = NULL; 957 char *fp; 958 959 memset(dch, '\0', sizeof(*dch)); 960 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 961 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 962 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 963 error_fr(r, "parse"); 964 goto out; 965 } 966 if (elen != 0) { 967 error_f("unsupported extensions (len %zu)", elen); 968 r = SSH_ERR_FEATURE_UNSUPPORTED; 969 goto out; 970 } 971 if (*dch->hostname == '\0') { 972 free(dch->hostname); 973 dch->hostname = NULL; 974 } 975 if (*dch->user == '\0') { 976 free(dch->user); 977 dch->user = NULL; 978 } 979 while (sshbuf_len(b) != 0) { 980 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 981 dch->nkeys + 1, sizeof(*dch->keys)); 982 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 983 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 984 if ((r = sshkey_froms(b, &k)) != 0 || 985 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 986 goto out; 987 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 988 SSH_FP_DEFAULT)) == NULL) 989 fatal_f("fingerprint failed"); 990 debug3_f("%s%s%s: adding %skey %s %s", 991 dch->user == NULL ? "" : dch->user, 992 dch->user == NULL ? "" : "@", 993 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 994 free(fp); 995 dch->keys[dch->nkeys] = k; 996 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 997 dch->nkeys++; 998 k = NULL; /* transferred */ 999 } 1000 /* success */ 1001 r = 0; 1002 out: 1003 sshkey_free(k); 1004 return r; 1005 } 1006 1007 static int 1008 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1009 { 1010 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1011 int r; 1012 size_t elen = 0; 1013 1014 debug3_f("entering"); 1015 1016 memset(dc, '\0', sizeof(*dc)); 1017 if ((r = sshbuf_froms(m, &b)) != 0 || 1018 (r = sshbuf_froms(b, &frombuf)) != 0 || 1019 (r = sshbuf_froms(b, &tobuf)) != 0 || 1020 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1021 error_fr(r, "parse"); 1022 goto out; 1023 } 1024 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1025 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1026 goto out; /* already logged */ 1027 if (elen != 0) { 1028 error_f("unsupported extensions (len %zu)", elen); 1029 r = SSH_ERR_FEATURE_UNSUPPORTED; 1030 goto out; 1031 } 1032 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1033 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1034 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1035 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1036 /* check consistency */ 1037 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1038 dc->from.user != NULL) { 1039 error_f("inconsistent \"from\" specification"); 1040 r = SSH_ERR_INVALID_FORMAT; 1041 goto out; 1042 } 1043 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1044 error_f("incomplete \"to\" specification"); 1045 r = SSH_ERR_INVALID_FORMAT; 1046 goto out; 1047 } 1048 /* success */ 1049 r = 0; 1050 out: 1051 sshbuf_free(b); 1052 sshbuf_free(frombuf); 1053 sshbuf_free(tobuf); 1054 return r; 1055 } 1056 1057 static int 1058 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1059 struct dest_constraint **dcsp, size_t *ndcsp) 1060 { 1061 char *ext_name = NULL; 1062 int r; 1063 struct sshbuf *b = NULL; 1064 1065 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1066 error_fr(r, "parse constraint extension"); 1067 goto out; 1068 } 1069 debug_f("constraint ext %s", ext_name); 1070 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1071 if (sk_providerp == NULL) { 1072 error_f("%s not valid here", ext_name); 1073 r = SSH_ERR_INVALID_FORMAT; 1074 goto out; 1075 } 1076 if (*sk_providerp != NULL) { 1077 error_f("%s already set", ext_name); 1078 r = SSH_ERR_INVALID_FORMAT; 1079 goto out; 1080 } 1081 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1082 error_fr(r, "parse %s", ext_name); 1083 goto out; 1084 } 1085 } else if (strcmp(ext_name, 1086 "restrict-destination-v00@openssh.com") == 0) { 1087 if (*dcsp != NULL) { 1088 error_f("%s already set", ext_name); 1089 goto out; 1090 } 1091 if ((r = sshbuf_froms(m, &b)) != 0) { 1092 error_fr(r, "parse %s outer", ext_name); 1093 goto out; 1094 } 1095 while (sshbuf_len(b) != 0) { 1096 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1097 error_f("too many %s constraints", ext_name); 1098 goto out; 1099 } 1100 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1101 sizeof(**dcsp)); 1102 if ((r = parse_dest_constraint(b, 1103 *dcsp + (*ndcsp)++)) != 0) 1104 goto out; /* error already logged */ 1105 } 1106 } else { 1107 error_f("unsupported constraint \"%s\"", ext_name); 1108 r = SSH_ERR_FEATURE_UNSUPPORTED; 1109 goto out; 1110 } 1111 /* success */ 1112 r = 0; 1113 out: 1114 free(ext_name); 1115 sshbuf_free(b); 1116 return r; 1117 } 1118 1119 static int 1120 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1121 u_int *secondsp, int *confirmp, char **sk_providerp, 1122 struct dest_constraint **dcsp, size_t *ndcsp) 1123 { 1124 u_char ctype; 1125 int r; 1126 u_int seconds, maxsign = 0; 1127 1128 while (sshbuf_len(m)) { 1129 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1130 error_fr(r, "parse constraint type"); 1131 goto out; 1132 } 1133 switch (ctype) { 1134 case SSH_AGENT_CONSTRAIN_LIFETIME: 1135 if (*deathp != 0) { 1136 error_f("lifetime already set"); 1137 r = SSH_ERR_INVALID_FORMAT; 1138 goto out; 1139 } 1140 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1141 error_fr(r, "parse lifetime constraint"); 1142 goto out; 1143 } 1144 *deathp = monotime() + seconds; 1145 *secondsp = seconds; 1146 break; 1147 case SSH_AGENT_CONSTRAIN_CONFIRM: 1148 if (*confirmp != 0) { 1149 error_f("confirm already set"); 1150 r = SSH_ERR_INVALID_FORMAT; 1151 goto out; 1152 } 1153 *confirmp = 1; 1154 break; 1155 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1156 if (k == NULL) { 1157 error_f("maxsign not valid here"); 1158 r = SSH_ERR_INVALID_FORMAT; 1159 goto out; 1160 } 1161 if (maxsign != 0) { 1162 error_f("maxsign already set"); 1163 r = SSH_ERR_INVALID_FORMAT; 1164 goto out; 1165 } 1166 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1167 error_fr(r, "parse maxsign constraint"); 1168 goto out; 1169 } 1170 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1171 error_fr(r, "enable maxsign"); 1172 goto out; 1173 } 1174 break; 1175 case SSH_AGENT_CONSTRAIN_EXTENSION: 1176 if ((r = parse_key_constraint_extension(m, 1177 sk_providerp, dcsp, ndcsp)) != 0) 1178 goto out; /* error already logged */ 1179 break; 1180 default: 1181 error_f("Unknown constraint %d", ctype); 1182 r = SSH_ERR_FEATURE_UNSUPPORTED; 1183 goto out; 1184 } 1185 } 1186 /* success */ 1187 r = 0; 1188 out: 1189 return r; 1190 } 1191 1192 static void 1193 process_add_identity(SocketEntry *e) 1194 { 1195 Identity *id; 1196 int success = 0, confirm = 0; 1197 char *fp, *comment = NULL, *sk_provider = NULL; 1198 char canonical_provider[PATH_MAX]; 1199 time_t death = 0; 1200 u_int seconds = 0; 1201 struct dest_constraint *dest_constraints = NULL; 1202 size_t ndest_constraints = 0; 1203 struct sshkey *k = NULL; 1204 int r = SSH_ERR_INTERNAL_ERROR; 1205 1206 debug2_f("entering"); 1207 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1208 k == NULL || 1209 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1210 error_fr(r, "parse"); 1211 goto out; 1212 } 1213 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1214 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1215 error_f("failed to parse constraints"); 1216 sshbuf_reset(e->request); 1217 goto out; 1218 } 1219 1220 if (sk_provider != NULL) { 1221 if (!sshkey_is_sk(k)) { 1222 error("Cannot add provider: %s is not an " 1223 "authenticator-hosted key", sshkey_type(k)); 1224 goto out; 1225 } 1226 if (strcasecmp(sk_provider, "internal") == 0) { 1227 debug_f("internal provider"); 1228 } else { 1229 if (realpath(sk_provider, canonical_provider) == NULL) { 1230 verbose("failed provider \"%.100s\": " 1231 "realpath: %s", sk_provider, 1232 strerror(errno)); 1233 goto out; 1234 } 1235 free(sk_provider); 1236 sk_provider = xstrdup(canonical_provider); 1237 if (match_pattern_list(sk_provider, 1238 allowed_providers, 0) != 1) { 1239 error("Refusing add key: " 1240 "provider %s not allowed", sk_provider); 1241 goto out; 1242 } 1243 } 1244 } 1245 if ((r = sshkey_shield_private(k)) != 0) { 1246 error_fr(r, "shield private"); 1247 goto out; 1248 } 1249 if (lifetime && !death) 1250 death = monotime() + lifetime; 1251 if ((id = lookup_identity(k)) == NULL) { 1252 id = xcalloc(1, sizeof(Identity)); 1253 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1254 /* Increment the number of identities. */ 1255 idtab->nentries++; 1256 } else { 1257 /* identity not visible, do not update */ 1258 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1259 goto out; /* error already logged */ 1260 /* key state might have been updated */ 1261 sshkey_free(id->key); 1262 free(id->comment); 1263 free(id->sk_provider); 1264 free_dest_constraints(id->dest_constraints, 1265 id->ndest_constraints); 1266 } 1267 /* success */ 1268 id->key = k; 1269 id->comment = comment; 1270 id->death = death; 1271 id->confirm = confirm; 1272 id->sk_provider = sk_provider; 1273 id->dest_constraints = dest_constraints; 1274 id->ndest_constraints = ndest_constraints; 1275 1276 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1277 SSH_FP_DEFAULT)) == NULL) 1278 fatal_f("sshkey_fingerprint failed"); 1279 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1280 "(provider: %s) (destination constraints: %zu)", 1281 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1282 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1283 free(fp); 1284 /* transferred */ 1285 k = NULL; 1286 comment = NULL; 1287 sk_provider = NULL; 1288 dest_constraints = NULL; 1289 ndest_constraints = 0; 1290 success = 1; 1291 out: 1292 free(sk_provider); 1293 free(comment); 1294 sshkey_free(k); 1295 free_dest_constraints(dest_constraints, ndest_constraints); 1296 send_status(e, success); 1297 } 1298 1299 /* XXX todo: encrypt sensitive data with passphrase */ 1300 static void 1301 process_lock_agent(SocketEntry *e, int lock) 1302 { 1303 int r, success = 0, delay; 1304 char *passwd; 1305 u_char passwdhash[LOCK_SIZE]; 1306 static u_int fail_count = 0; 1307 size_t pwlen; 1308 1309 debug2_f("entering"); 1310 /* 1311 * This is deliberately fatal: the user has requested that we lock, 1312 * but we can't parse their request properly. The only safe thing to 1313 * do is abort. 1314 */ 1315 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1316 fatal_fr(r, "parse"); 1317 if (pwlen == 0) { 1318 debug("empty password not supported"); 1319 } else if (locked && !lock) { 1320 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1321 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1322 fatal("bcrypt_pbkdf"); 1323 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1324 debug("agent unlocked"); 1325 locked = 0; 1326 fail_count = 0; 1327 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1328 success = 1; 1329 } else { 1330 /* delay in 0.1s increments up to 10s */ 1331 if (fail_count < 100) 1332 fail_count++; 1333 delay = 100000 * fail_count; 1334 debug("unlock failed, delaying %0.1lf seconds", 1335 (double)delay/1000000); 1336 usleep(delay); 1337 } 1338 explicit_bzero(passwdhash, sizeof(passwdhash)); 1339 } else if (!locked && lock) { 1340 debug("agent locked"); 1341 locked = 1; 1342 arc4random_buf(lock_salt, sizeof(lock_salt)); 1343 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1344 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1345 fatal("bcrypt_pbkdf"); 1346 success = 1; 1347 } 1348 freezero(passwd, pwlen); 1349 send_status(e, success); 1350 } 1351 1352 static void 1353 no_identities(SocketEntry *e) 1354 { 1355 struct sshbuf *msg; 1356 int r; 1357 1358 if ((msg = sshbuf_new()) == NULL) 1359 fatal_f("sshbuf_new failed"); 1360 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1361 (r = sshbuf_put_u32(msg, 0)) != 0 || 1362 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1363 fatal_fr(r, "compose"); 1364 sshbuf_free(msg); 1365 } 1366 1367 #ifdef ENABLE_PKCS11 1368 static void 1369 process_add_smartcard_key(SocketEntry *e) 1370 { 1371 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1372 char **comments = NULL; 1373 int r, i, count = 0, success = 0, confirm = 0; 1374 u_int seconds = 0; 1375 time_t death = 0; 1376 struct sshkey **keys = NULL, *k; 1377 Identity *id; 1378 struct dest_constraint *dest_constraints = NULL; 1379 size_t ndest_constraints = 0; 1380 1381 debug2_f("entering"); 1382 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1383 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1384 error_fr(r, "parse"); 1385 goto send; 1386 } 1387 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1388 NULL, &dest_constraints, &ndest_constraints) != 0) { 1389 error_f("failed to parse constraints"); 1390 goto send; 1391 } 1392 if (realpath(provider, canonical_provider) == NULL) { 1393 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1394 provider, strerror(errno)); 1395 goto send; 1396 } 1397 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1398 verbose("refusing PKCS#11 add of \"%.100s\": " 1399 "provider not allowed", canonical_provider); 1400 goto send; 1401 } 1402 debug_f("add %.100s", canonical_provider); 1403 if (lifetime && !death) 1404 death = monotime() + lifetime; 1405 1406 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1407 for (i = 0; i < count; i++) { 1408 k = keys[i]; 1409 if (lookup_identity(k) == NULL) { 1410 id = xcalloc(1, sizeof(Identity)); 1411 id->key = k; 1412 keys[i] = NULL; /* transferred */ 1413 id->provider = xstrdup(canonical_provider); 1414 if (*comments[i] != '\0') { 1415 id->comment = comments[i]; 1416 comments[i] = NULL; /* transferred */ 1417 } else { 1418 id->comment = xstrdup(canonical_provider); 1419 } 1420 id->death = death; 1421 id->confirm = confirm; 1422 id->dest_constraints = dest_constraints; 1423 id->ndest_constraints = ndest_constraints; 1424 dest_constraints = NULL; /* transferred */ 1425 ndest_constraints = 0; 1426 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1427 idtab->nentries++; 1428 success = 1; 1429 } 1430 /* XXX update constraints for existing keys */ 1431 sshkey_free(keys[i]); 1432 free(comments[i]); 1433 } 1434 send: 1435 free(pin); 1436 free(provider); 1437 free(keys); 1438 free(comments); 1439 free_dest_constraints(dest_constraints, ndest_constraints); 1440 send_status(e, success); 1441 } 1442 1443 static void 1444 process_remove_smartcard_key(SocketEntry *e) 1445 { 1446 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1447 int r, success = 0; 1448 Identity *id, *nxt; 1449 1450 debug2_f("entering"); 1451 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1452 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1453 error_fr(r, "parse"); 1454 goto send; 1455 } 1456 free(pin); 1457 1458 if (realpath(provider, canonical_provider) == NULL) { 1459 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1460 provider, strerror(errno)); 1461 goto send; 1462 } 1463 1464 debug_f("remove %.100s", canonical_provider); 1465 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1466 nxt = TAILQ_NEXT(id, next); 1467 /* Skip file--based keys */ 1468 if (id->provider == NULL) 1469 continue; 1470 if (!strcmp(canonical_provider, id->provider)) { 1471 TAILQ_REMOVE(&idtab->idlist, id, next); 1472 free_identity(id); 1473 idtab->nentries--; 1474 } 1475 } 1476 if (pkcs11_del_provider(canonical_provider) == 0) 1477 success = 1; 1478 else 1479 error_f("pkcs11_del_provider failed"); 1480 send: 1481 free(provider); 1482 send_status(e, success); 1483 } 1484 #endif /* ENABLE_PKCS11 */ 1485 1486 static int 1487 process_ext_session_bind(SocketEntry *e) 1488 { 1489 int r, sid_match, key_match; 1490 struct sshkey *key = NULL; 1491 struct sshbuf *sid = NULL, *sig = NULL; 1492 char *fp = NULL; 1493 size_t i; 1494 u_char fwd = 0; 1495 1496 debug2_f("entering"); 1497 if ((r = sshkey_froms(e->request, &key)) != 0 || 1498 (r = sshbuf_froms(e->request, &sid)) != 0 || 1499 (r = sshbuf_froms(e->request, &sig)) != 0 || 1500 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1501 error_fr(r, "parse"); 1502 goto out; 1503 } 1504 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1505 SSH_FP_DEFAULT)) == NULL) 1506 fatal_f("fingerprint failed"); 1507 /* check signature with hostkey on session ID */ 1508 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1509 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1510 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1511 goto out; 1512 } 1513 /* check whether sid/key already recorded */ 1514 for (i = 0; i < e->nsession_ids; i++) { 1515 if (!e->session_ids[i].forwarded) { 1516 error_f("attempt to bind session ID to socket " 1517 "previously bound for authentication attempt"); 1518 r = -1; 1519 goto out; 1520 } 1521 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1522 key_match = sshkey_equal(key, e->session_ids[i].key); 1523 if (sid_match && key_match) { 1524 debug_f("session ID already recorded for %s %s", 1525 sshkey_type(key), fp); 1526 r = 0; 1527 goto out; 1528 } else if (sid_match) { 1529 error_f("session ID recorded against different key " 1530 "for %s %s", sshkey_type(key), fp); 1531 r = -1; 1532 goto out; 1533 } 1534 /* 1535 * new sid with previously-seen key can happen, e.g. multiple 1536 * connections to the same host. 1537 */ 1538 } 1539 /* record new key/sid */ 1540 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1541 error_f("too many session IDs recorded"); 1542 goto out; 1543 } 1544 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1545 e->nsession_ids + 1, sizeof(*e->session_ids)); 1546 i = e->nsession_ids++; 1547 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1548 AGENT_MAX_SESSION_IDS); 1549 e->session_ids[i].key = key; 1550 e->session_ids[i].forwarded = fwd != 0; 1551 key = NULL; /* transferred */ 1552 /* can't transfer sid; it's refcounted and scoped to request's life */ 1553 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1554 fatal_f("sshbuf_new"); 1555 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1556 fatal_fr(r, "sshbuf_putb session ID"); 1557 /* success */ 1558 r = 0; 1559 out: 1560 free(fp); 1561 sshkey_free(key); 1562 sshbuf_free(sid); 1563 sshbuf_free(sig); 1564 return r == 0 ? 1 : 0; 1565 } 1566 1567 static void 1568 process_extension(SocketEntry *e) 1569 { 1570 int r, success = 0; 1571 char *name; 1572 1573 debug2_f("entering"); 1574 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1575 error_fr(r, "parse"); 1576 goto send; 1577 } 1578 if (strcmp(name, "session-bind@openssh.com") == 0) 1579 success = process_ext_session_bind(e); 1580 else 1581 debug_f("unsupported extension \"%s\"", name); 1582 free(name); 1583 send: 1584 send_status(e, success); 1585 } 1586 /* 1587 * dispatch incoming message. 1588 * returns 1 on success, 0 for incomplete messages or -1 on error. 1589 */ 1590 static int 1591 process_message(u_int socknum) 1592 { 1593 u_int msg_len; 1594 u_char type; 1595 const u_char *cp; 1596 int r; 1597 SocketEntry *e; 1598 1599 if (socknum >= sockets_alloc) 1600 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1601 e = &sockets[socknum]; 1602 1603 if (sshbuf_len(e->input) < 5) 1604 return 0; /* Incomplete message header. */ 1605 cp = sshbuf_ptr(e->input); 1606 msg_len = PEEK_U32(cp); 1607 if (msg_len > AGENT_MAX_LEN) { 1608 debug_f("socket %u (fd=%d) message too long %u > %u", 1609 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1610 return -1; 1611 } 1612 if (sshbuf_len(e->input) < msg_len + 4) 1613 return 0; /* Incomplete message body. */ 1614 1615 /* move the current input to e->request */ 1616 sshbuf_reset(e->request); 1617 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1618 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1619 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1620 r == SSH_ERR_STRING_TOO_LARGE) { 1621 error_fr(r, "parse"); 1622 return -1; 1623 } 1624 fatal_fr(r, "parse"); 1625 } 1626 1627 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1628 1629 /* check whether agent is locked */ 1630 if (locked && type != SSH_AGENTC_UNLOCK) { 1631 sshbuf_reset(e->request); 1632 switch (type) { 1633 case SSH2_AGENTC_REQUEST_IDENTITIES: 1634 /* send empty lists */ 1635 no_identities(e); 1636 break; 1637 default: 1638 /* send a fail message for all other request types */ 1639 send_status(e, 0); 1640 } 1641 return 1; 1642 } 1643 1644 switch (type) { 1645 case SSH_AGENTC_LOCK: 1646 case SSH_AGENTC_UNLOCK: 1647 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1648 break; 1649 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1650 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1651 break; 1652 /* ssh2 */ 1653 case SSH2_AGENTC_SIGN_REQUEST: 1654 process_sign_request2(e); 1655 break; 1656 case SSH2_AGENTC_REQUEST_IDENTITIES: 1657 process_request_identities(e); 1658 break; 1659 case SSH2_AGENTC_ADD_IDENTITY: 1660 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1661 process_add_identity(e); 1662 break; 1663 case SSH2_AGENTC_REMOVE_IDENTITY: 1664 process_remove_identity(e); 1665 break; 1666 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1667 process_remove_all_identities(e); 1668 break; 1669 #ifdef ENABLE_PKCS11 1670 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1671 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1672 process_add_smartcard_key(e); 1673 break; 1674 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1675 process_remove_smartcard_key(e); 1676 break; 1677 #endif /* ENABLE_PKCS11 */ 1678 case SSH_AGENTC_EXTENSION: 1679 process_extension(e); 1680 break; 1681 default: 1682 /* Unknown message. Respond with failure. */ 1683 error("Unknown message %d", type); 1684 sshbuf_reset(e->request); 1685 send_status(e, 0); 1686 break; 1687 } 1688 return 1; 1689 } 1690 1691 static void 1692 new_socket(sock_type type, int fd) 1693 { 1694 u_int i, old_alloc, new_alloc; 1695 1696 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1697 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1698 set_nonblock(fd); 1699 1700 if (fd > max_fd) 1701 max_fd = fd; 1702 1703 for (i = 0; i < sockets_alloc; i++) 1704 if (sockets[i].type == AUTH_UNUSED) { 1705 sockets[i].fd = fd; 1706 if ((sockets[i].input = sshbuf_new()) == NULL || 1707 (sockets[i].output = sshbuf_new()) == NULL || 1708 (sockets[i].request = sshbuf_new()) == NULL) 1709 fatal_f("sshbuf_new failed"); 1710 sockets[i].type = type; 1711 return; 1712 } 1713 old_alloc = sockets_alloc; 1714 new_alloc = sockets_alloc + 10; 1715 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1716 sizeof(sockets[0])); 1717 for (i = old_alloc; i < new_alloc; i++) 1718 sockets[i].type = AUTH_UNUSED; 1719 sockets_alloc = new_alloc; 1720 sockets[old_alloc].fd = fd; 1721 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1722 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1723 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1724 fatal_f("sshbuf_new failed"); 1725 sockets[old_alloc].type = type; 1726 } 1727 1728 static int 1729 handle_socket_read(u_int socknum) 1730 { 1731 struct sockaddr_un sunaddr; 1732 socklen_t slen; 1733 uid_t euid; 1734 gid_t egid; 1735 int fd; 1736 1737 slen = sizeof(sunaddr); 1738 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1739 if (fd == -1) { 1740 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1741 return -1; 1742 } 1743 if (getpeereid(fd, &euid, &egid) == -1) { 1744 error("getpeereid %d failed: %s", fd, strerror(errno)); 1745 close(fd); 1746 return -1; 1747 } 1748 if ((euid != 0) && (getuid() != euid)) { 1749 error("uid mismatch: peer euid %u != uid %u", 1750 (u_int) euid, (u_int) getuid()); 1751 close(fd); 1752 return -1; 1753 } 1754 new_socket(AUTH_CONNECTION, fd); 1755 return 0; 1756 } 1757 1758 static int 1759 handle_conn_read(u_int socknum) 1760 { 1761 char buf[AGENT_RBUF_LEN]; 1762 ssize_t len; 1763 int r; 1764 1765 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 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_put(sockets[socknum].input, buf, len)) != 0) 1775 fatal_fr(r, "compose"); 1776 explicit_bzero(buf, sizeof(buf)); 1777 for (;;) { 1778 if ((r = process_message(socknum)) == -1) 1779 return -1; 1780 else if (r == 0) 1781 break; 1782 } 1783 return 0; 1784 } 1785 1786 static int 1787 handle_conn_write(u_int socknum) 1788 { 1789 ssize_t len; 1790 int r; 1791 1792 if (sshbuf_len(sockets[socknum].output) == 0) 1793 return 0; /* shouldn't happen */ 1794 if ((len = write(sockets[socknum].fd, 1795 sshbuf_ptr(sockets[socknum].output), 1796 sshbuf_len(sockets[socknum].output))) <= 0) { 1797 if (len == -1) { 1798 if (errno == EAGAIN || errno == EINTR) 1799 return 0; 1800 error_f("read error on socket %u (fd %d): %s", 1801 socknum, sockets[socknum].fd, strerror(errno)); 1802 } 1803 return -1; 1804 } 1805 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1806 fatal_fr(r, "consume"); 1807 return 0; 1808 } 1809 1810 static void 1811 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1812 { 1813 size_t i; 1814 u_int socknum, activefds = npfd; 1815 1816 for (i = 0; i < npfd; i++) { 1817 if (pfd[i].revents == 0) 1818 continue; 1819 /* Find sockets entry */ 1820 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1821 if (sockets[socknum].type != AUTH_SOCKET && 1822 sockets[socknum].type != AUTH_CONNECTION) 1823 continue; 1824 if (pfd[i].fd == sockets[socknum].fd) 1825 break; 1826 } 1827 if (socknum >= sockets_alloc) { 1828 error_f("no socket for fd %d", pfd[i].fd); 1829 continue; 1830 } 1831 /* Process events */ 1832 switch (sockets[socknum].type) { 1833 case AUTH_SOCKET: 1834 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1835 break; 1836 if (npfd > maxfds) { 1837 debug3("out of fds (active %u >= limit %u); " 1838 "skipping accept", activefds, maxfds); 1839 break; 1840 } 1841 if (handle_socket_read(socknum) == 0) 1842 activefds++; 1843 break; 1844 case AUTH_CONNECTION: 1845 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1846 handle_conn_read(socknum) != 0) 1847 goto close_sock; 1848 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1849 handle_conn_write(socknum) != 0) { 1850 close_sock: 1851 if (activefds == 0) 1852 fatal("activefds == 0 at close_sock"); 1853 close_socket(&sockets[socknum]); 1854 activefds--; 1855 break; 1856 } 1857 break; 1858 default: 1859 break; 1860 } 1861 } 1862 } 1863 1864 static int 1865 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1866 { 1867 struct pollfd *pfd = *pfdp; 1868 size_t i, j, npfd = 0; 1869 time_t deadline; 1870 int r; 1871 1872 /* Count active sockets */ 1873 for (i = 0; i < sockets_alloc; i++) { 1874 switch (sockets[i].type) { 1875 case AUTH_SOCKET: 1876 case AUTH_CONNECTION: 1877 npfd++; 1878 break; 1879 case AUTH_UNUSED: 1880 break; 1881 default: 1882 fatal("Unknown socket type %d", sockets[i].type); 1883 break; 1884 } 1885 } 1886 if (npfd != *npfdp && 1887 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1888 fatal_f("recallocarray failed"); 1889 *pfdp = pfd; 1890 *npfdp = npfd; 1891 1892 for (i = j = 0; i < sockets_alloc; i++) { 1893 switch (sockets[i].type) { 1894 case AUTH_SOCKET: 1895 if (npfd > maxfds) { 1896 debug3("out of fds (active %zu >= limit %u); " 1897 "skipping arming listener", npfd, maxfds); 1898 break; 1899 } 1900 pfd[j].fd = sockets[i].fd; 1901 pfd[j].revents = 0; 1902 pfd[j].events = POLLIN; 1903 j++; 1904 break; 1905 case AUTH_CONNECTION: 1906 pfd[j].fd = sockets[i].fd; 1907 pfd[j].revents = 0; 1908 /* 1909 * Only prepare to read if we can handle a full-size 1910 * input read buffer and enqueue a max size reply.. 1911 */ 1912 if ((r = sshbuf_check_reserve(sockets[i].input, 1913 AGENT_RBUF_LEN)) == 0 && 1914 (r = sshbuf_check_reserve(sockets[i].output, 1915 AGENT_MAX_LEN)) == 0) 1916 pfd[j].events = POLLIN; 1917 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1918 fatal_fr(r, "reserve"); 1919 if (sshbuf_len(sockets[i].output) > 0) 1920 pfd[j].events |= POLLOUT; 1921 j++; 1922 break; 1923 default: 1924 break; 1925 } 1926 } 1927 deadline = reaper(); 1928 if (parent_alive_interval != 0) 1929 deadline = (deadline == 0) ? parent_alive_interval : 1930 MINIMUM(deadline, parent_alive_interval); 1931 if (deadline == 0) { 1932 *timeoutp = -1; /* INFTIM */ 1933 } else { 1934 if (deadline > INT_MAX / 1000) 1935 *timeoutp = INT_MAX / 1000; 1936 else 1937 *timeoutp = deadline * 1000; 1938 } 1939 return (1); 1940 } 1941 1942 static void 1943 cleanup_socket(void) 1944 { 1945 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1946 return; 1947 debug_f("cleanup"); 1948 if (socket_name[0]) 1949 unlink(socket_name); 1950 if (socket_dir[0]) 1951 rmdir(socket_dir); 1952 } 1953 1954 void 1955 cleanup_exit(int i) 1956 { 1957 cleanup_socket(); 1958 _exit(i); 1959 } 1960 1961 /*ARGSUSED*/ 1962 static void 1963 cleanup_handler(int sig) 1964 { 1965 cleanup_socket(); 1966 #ifdef ENABLE_PKCS11 1967 pkcs11_terminate(); 1968 #endif 1969 _exit(2); 1970 } 1971 1972 static void 1973 check_parent_exists(void) 1974 { 1975 /* 1976 * If our parent has exited then getppid() will return (pid_t)1, 1977 * so testing for that should be safe. 1978 */ 1979 if (parent_pid != -1 && getppid() != parent_pid) { 1980 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1981 cleanup_socket(); 1982 _exit(2); 1983 } 1984 } 1985 1986 static void 1987 usage(void) 1988 { 1989 fprintf(stderr, 1990 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1991 " [-P allowed_providers] [-t life]\n" 1992 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1993 " [-t life] command [arg ...]\n" 1994 " ssh-agent [-c | -s] -k\n"); 1995 exit(1); 1996 } 1997 1998 int 1999 main(int ac, char **av) 2000 { 2001 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2002 int sock, ch, result, saved_errno; 2003 char *shell, *format, *pidstr, *agentsocket = NULL; 2004 struct rlimit rlim; 2005 extern int optind; 2006 extern char *optarg; 2007 pid_t pid; 2008 char pidstrbuf[1 + 3 * sizeof pid]; 2009 size_t len; 2010 mode_t prev_mask; 2011 int timeout = -1; /* INFTIM */ 2012 struct pollfd *pfd = NULL; 2013 size_t npfd = 0; 2014 u_int maxfds; 2015 2016 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2017 sanitise_stdfd(); 2018 2019 /* drop */ 2020 setegid(getgid()); 2021 setgid(getgid()); 2022 2023 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2024 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2025 2026 #ifdef WITH_OPENSSL 2027 OpenSSL_add_all_algorithms(); 2028 #endif 2029 2030 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2031 switch (ch) { 2032 case 'E': 2033 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2034 if (fingerprint_hash == -1) 2035 fatal("Invalid hash algorithm \"%s\"", optarg); 2036 break; 2037 case 'c': 2038 if (s_flag) 2039 usage(); 2040 c_flag++; 2041 break; 2042 case 'k': 2043 k_flag++; 2044 break; 2045 case 'O': 2046 if (strcmp(optarg, "no-restrict-websafe") == 0) 2047 restrict_websafe = 0; 2048 else 2049 fatal("Unknown -O option"); 2050 break; 2051 case 'P': 2052 if (allowed_providers != NULL) 2053 fatal("-P option already specified"); 2054 allowed_providers = xstrdup(optarg); 2055 break; 2056 case 's': 2057 if (c_flag) 2058 usage(); 2059 s_flag++; 2060 break; 2061 case 'd': 2062 if (d_flag || D_flag) 2063 usage(); 2064 d_flag++; 2065 break; 2066 case 'D': 2067 if (d_flag || D_flag) 2068 usage(); 2069 D_flag++; 2070 break; 2071 case 'a': 2072 agentsocket = optarg; 2073 break; 2074 case 't': 2075 if ((lifetime = convtime(optarg)) == -1) { 2076 fprintf(stderr, "Invalid lifetime\n"); 2077 usage(); 2078 } 2079 break; 2080 default: 2081 usage(); 2082 } 2083 } 2084 ac -= optind; 2085 av += optind; 2086 2087 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2088 usage(); 2089 2090 if (allowed_providers == NULL) 2091 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2092 2093 if (ac == 0 && !c_flag && !s_flag) { 2094 shell = getenv("SHELL"); 2095 if (shell != NULL && (len = strlen(shell)) > 2 && 2096 strncmp(shell + len - 3, "csh", 3) == 0) 2097 c_flag = 1; 2098 } 2099 if (k_flag) { 2100 const char *errstr = NULL; 2101 2102 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2103 if (pidstr == NULL) { 2104 fprintf(stderr, "%s not set, cannot kill agent\n", 2105 SSH_AGENTPID_ENV_NAME); 2106 exit(1); 2107 } 2108 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2109 if (errstr) { 2110 fprintf(stderr, 2111 "%s=\"%s\", which is not a good PID: %s\n", 2112 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2113 exit(1); 2114 } 2115 if (kill(pid, SIGTERM) == -1) { 2116 perror("kill"); 2117 exit(1); 2118 } 2119 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2120 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2121 printf(format, SSH_AGENTPID_ENV_NAME); 2122 printf("echo Agent pid %ld killed;\n", (long)pid); 2123 exit(0); 2124 } 2125 2126 /* 2127 * Minimum file descriptors: 2128 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2129 * a few spare for libc / stack protectors / sanitisers, etc. 2130 */ 2131 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2132 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2133 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2134 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2135 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2136 2137 parent_pid = getpid(); 2138 2139 if (agentsocket == NULL) { 2140 /* Create private directory for agent socket */ 2141 mktemp_proto(socket_dir, sizeof(socket_dir)); 2142 if (mkdtemp(socket_dir) == NULL) { 2143 perror("mkdtemp: private socket dir"); 2144 exit(1); 2145 } 2146 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2147 (long)parent_pid); 2148 } else { 2149 /* Try to use specified agent socket */ 2150 socket_dir[0] = '\0'; 2151 strlcpy(socket_name, agentsocket, sizeof socket_name); 2152 } 2153 2154 /* 2155 * Create socket early so it will exist before command gets run from 2156 * the parent. 2157 */ 2158 prev_mask = umask(0177); 2159 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2160 if (sock < 0) { 2161 /* XXX - unix_listener() calls error() not perror() */ 2162 *socket_name = '\0'; /* Don't unlink any existing file */ 2163 cleanup_exit(1); 2164 } 2165 umask(prev_mask); 2166 2167 /* 2168 * Fork, and have the parent execute the command, if any, or present 2169 * the socket data. The child continues as the authentication agent. 2170 */ 2171 if (D_flag || d_flag) { 2172 log_init(__progname, 2173 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2174 SYSLOG_FACILITY_AUTH, 1); 2175 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2176 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2177 SSH_AUTHSOCKET_ENV_NAME); 2178 printf("echo Agent pid %ld;\n", (long)parent_pid); 2179 fflush(stdout); 2180 goto skip; 2181 } 2182 pid = fork(); 2183 if (pid == -1) { 2184 perror("fork"); 2185 cleanup_exit(1); 2186 } 2187 if (pid != 0) { /* Parent - execute the given command. */ 2188 close(sock); 2189 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2190 if (ac == 0) { 2191 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2192 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2193 SSH_AUTHSOCKET_ENV_NAME); 2194 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2195 SSH_AGENTPID_ENV_NAME); 2196 printf("echo Agent pid %ld;\n", (long)pid); 2197 exit(0); 2198 } 2199 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2200 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2201 perror("setenv"); 2202 exit(1); 2203 } 2204 execvp(av[0], av); 2205 perror(av[0]); 2206 exit(1); 2207 } 2208 /* child */ 2209 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2210 2211 if (setsid() == -1) { 2212 error("setsid: %s", strerror(errno)); 2213 cleanup_exit(1); 2214 } 2215 2216 (void)chdir("/"); 2217 if (stdfd_devnull(1, 1, 1) == -1) 2218 error_f("stdfd_devnull failed"); 2219 2220 /* deny core dumps, since memory contains unencrypted private keys */ 2221 rlim.rlim_cur = rlim.rlim_max = 0; 2222 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2223 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2224 cleanup_exit(1); 2225 } 2226 2227 skip: 2228 2229 cleanup_pid = getpid(); 2230 2231 #ifdef ENABLE_PKCS11 2232 pkcs11_init(0); 2233 #endif 2234 new_socket(AUTH_SOCKET, sock); 2235 if (ac > 0) 2236 parent_alive_interval = 10; 2237 idtab_init(); 2238 ssh_signal(SIGPIPE, SIG_IGN); 2239 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2240 ssh_signal(SIGHUP, cleanup_handler); 2241 ssh_signal(SIGTERM, cleanup_handler); 2242 2243 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2244 fatal("%s: pledge: %s", __progname, strerror(errno)); 2245 2246 while (1) { 2247 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2248 result = poll(pfd, npfd, timeout); 2249 saved_errno = errno; 2250 if (parent_alive_interval != 0) 2251 check_parent_exists(); 2252 (void) reaper(); /* remove expired keys */ 2253 if (result == -1) { 2254 if (saved_errno == EINTR) 2255 continue; 2256 fatal("poll: %s", strerror(saved_errno)); 2257 } else if (result > 0) 2258 after_poll(pfd, npfd, maxfds); 2259 } 2260 /* NOTREACHED */ 2261 } 2262