1 /* $OpenBSD: ssh-agent.c,v 1.300 2023/07/19 13:56:33 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 "log.h" 71 #include "misc.h" 72 #include "digest.h" 73 #include "ssherr.h" 74 #include "match.h" 75 #include "msg.h" 76 #include "pathnames.h" 77 #include "ssh-pkcs11.h" 78 #include "sk-api.h" 79 #include "myproposal.h" 80 81 #ifndef DEFAULT_ALLOWED_PROVIDERS 82 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 83 #endif 84 85 /* Maximum accepted message length */ 86 #define AGENT_MAX_LEN (256*1024) 87 /* Maximum bytes to read from client socket */ 88 #define AGENT_RBUF_LEN (4096) 89 /* Maximum number of recorded session IDs/hostkeys per connection */ 90 #define AGENT_MAX_SESSION_IDS 16 91 /* Maximum size of session ID */ 92 #define AGENT_MAX_SID_LEN 128 93 /* Maximum number of destination constraints to accept on a key */ 94 #define AGENT_MAX_DEST_CONSTRAINTS 1024 95 96 /* XXX store hostkey_sid in a refcounted tree */ 97 98 typedef enum { 99 AUTH_UNUSED = 0, 100 AUTH_SOCKET = 1, 101 AUTH_CONNECTION = 2, 102 } sock_type; 103 104 struct hostkey_sid { 105 struct sshkey *key; 106 struct sshbuf *sid; 107 int forwarded; 108 }; 109 110 typedef struct socket_entry { 111 int fd; 112 sock_type type; 113 struct sshbuf *input; 114 struct sshbuf *output; 115 struct sshbuf *request; 116 size_t nsession_ids; 117 struct hostkey_sid *session_ids; 118 } SocketEntry; 119 120 u_int sockets_alloc = 0; 121 SocketEntry *sockets = NULL; 122 123 typedef struct identity { 124 TAILQ_ENTRY(identity) next; 125 struct sshkey *key; 126 char *comment; 127 char *provider; 128 time_t death; 129 u_int confirm; 130 char *sk_provider; 131 struct dest_constraint *dest_constraints; 132 size_t ndest_constraints; 133 } Identity; 134 135 struct idtable { 136 int nentries; 137 TAILQ_HEAD(idqueue, identity) idlist; 138 }; 139 140 /* private key table */ 141 struct idtable *idtab; 142 143 int max_fd = 0; 144 145 /* pid of shell == parent of agent */ 146 pid_t parent_pid = -1; 147 time_t parent_alive_interval = 0; 148 149 /* pid of process for which cleanup_socket is applicable */ 150 pid_t cleanup_pid = 0; 151 152 /* pathname and directory for AUTH_SOCKET */ 153 char socket_name[PATH_MAX]; 154 char socket_dir[PATH_MAX]; 155 156 /* Pattern-list of allowed PKCS#11/Security key paths */ 157 static char *allowed_providers; 158 159 /* 160 * Allows PKCS11 providers or SK keys that use non-internal providers to 161 * be added over a remote connection (identified by session-bind@openssh.com). 162 */ 163 static int remote_add_provider; 164 165 /* locking */ 166 #define LOCK_SIZE 32 167 #define LOCK_SALT_SIZE 16 168 #define LOCK_ROUNDS 1 169 int locked = 0; 170 u_char lock_pwhash[LOCK_SIZE]; 171 u_char lock_salt[LOCK_SALT_SIZE]; 172 173 extern char *__progname; 174 175 /* Default lifetime in seconds (0 == forever) */ 176 static int lifetime = 0; 177 178 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 179 180 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 181 static int restrict_websafe = 1; 182 183 static void 184 close_socket(SocketEntry *e) 185 { 186 size_t i; 187 188 close(e->fd); 189 sshbuf_free(e->input); 190 sshbuf_free(e->output); 191 sshbuf_free(e->request); 192 for (i = 0; i < e->nsession_ids; i++) { 193 sshkey_free(e->session_ids[i].key); 194 sshbuf_free(e->session_ids[i].sid); 195 } 196 free(e->session_ids); 197 memset(e, '\0', sizeof(*e)); 198 e->fd = -1; 199 e->type = AUTH_UNUSED; 200 } 201 202 static void 203 idtab_init(void) 204 { 205 idtab = xcalloc(1, sizeof(*idtab)); 206 TAILQ_INIT(&idtab->idlist); 207 idtab->nentries = 0; 208 } 209 210 static void 211 free_dest_constraint_hop(struct dest_constraint_hop *dch) 212 { 213 u_int i; 214 215 if (dch == NULL) 216 return; 217 free(dch->user); 218 free(dch->hostname); 219 for (i = 0; i < dch->nkeys; i++) 220 sshkey_free(dch->keys[i]); 221 free(dch->keys); 222 free(dch->key_is_ca); 223 } 224 225 static void 226 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 227 { 228 size_t i; 229 230 for (i = 0; i < ndcs; i++) { 231 free_dest_constraint_hop(&dcs[i].from); 232 free_dest_constraint_hop(&dcs[i].to); 233 } 234 free(dcs); 235 } 236 237 static void 238 free_identity(Identity *id) 239 { 240 sshkey_free(id->key); 241 free(id->provider); 242 free(id->comment); 243 free(id->sk_provider); 244 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 245 free(id); 246 } 247 248 /* 249 * Match 'key' against the key/CA list in a destination constraint hop 250 * Returns 0 on success or -1 otherwise. 251 */ 252 static int 253 match_key_hop(const char *tag, const struct sshkey *key, 254 const struct dest_constraint_hop *dch) 255 { 256 const char *reason = NULL; 257 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 258 u_int i; 259 char *fp; 260 261 if (key == NULL) 262 return -1; 263 /* XXX logspam */ 264 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 265 SSH_FP_DEFAULT)) == NULL) 266 fatal_f("fingerprint failed"); 267 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 268 tag, hostname, sshkey_type(key), fp, dch->nkeys); 269 free(fp); 270 for (i = 0; i < dch->nkeys; i++) { 271 if (dch->keys[i] == NULL) 272 return -1; 273 /* XXX logspam */ 274 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 275 SSH_FP_DEFAULT)) == NULL) 276 fatal_f("fingerprint failed"); 277 debug3_f("%s: key %u: %s%s %s", tag, i, 278 dch->key_is_ca[i] ? "CA " : "", 279 sshkey_type(dch->keys[i]), fp); 280 free(fp); 281 if (!sshkey_is_cert(key)) { 282 /* plain key */ 283 if (dch->key_is_ca[i] || 284 !sshkey_equal(key, dch->keys[i])) 285 continue; 286 return 0; 287 } 288 /* certificate */ 289 if (!dch->key_is_ca[i]) 290 continue; 291 if (key->cert == NULL || key->cert->signature_key == NULL) 292 return -1; /* shouldn't happen */ 293 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 294 continue; 295 if (sshkey_cert_check_host(key, hostname, 1, 296 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 297 debug_f("cert %s / hostname %s rejected: %s", 298 key->cert->key_id, hostname, reason); 299 continue; 300 } 301 return 0; 302 } 303 return -1; 304 } 305 306 /* Check destination constraints on an identity against the hostkey/user */ 307 static int 308 permitted_by_dest_constraints(const struct sshkey *fromkey, 309 const struct sshkey *tokey, Identity *id, const char *user, 310 const char **hostnamep) 311 { 312 size_t i; 313 struct dest_constraint *d; 314 315 if (hostnamep != NULL) 316 *hostnamep = NULL; 317 for (i = 0; i < id->ndest_constraints; i++) { 318 d = id->dest_constraints + i; 319 /* XXX remove logspam */ 320 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 321 i, d->from.user ? d->from.user : "", 322 d->from.user ? "@" : "", 323 d->from.hostname ? d->from.hostname : "(ORIGIN)", 324 d->from.nkeys, 325 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 326 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 327 328 /* Match 'from' key */ 329 if (fromkey == NULL) { 330 /* We are matching the first hop */ 331 if (d->from.hostname != NULL || d->from.nkeys != 0) 332 continue; 333 } else if (match_key_hop("from", fromkey, &d->from) != 0) 334 continue; 335 336 /* Match 'to' key */ 337 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 338 continue; 339 340 /* Match user if specified */ 341 if (d->to.user != NULL && user != NULL && 342 !match_pattern(user, d->to.user)) 343 continue; 344 345 /* successfully matched this constraint */ 346 if (hostnamep != NULL) 347 *hostnamep = d->to.hostname; 348 debug2_f("allowed for hostname %s", 349 d->to.hostname == NULL ? "*" : d->to.hostname); 350 return 0; 351 } 352 /* no match */ 353 debug2_f("%s identity \"%s\" not permitted for this destination", 354 sshkey_type(id->key), id->comment); 355 return -1; 356 } 357 358 /* 359 * Check whether hostkeys on a SocketEntry and the optionally specified user 360 * are permitted by the destination constraints on the Identity. 361 * Returns 0 on success or -1 otherwise. 362 */ 363 static int 364 identity_permitted(Identity *id, SocketEntry *e, char *user, 365 const char **forward_hostnamep, const char **last_hostnamep) 366 { 367 size_t i; 368 const char **hp; 369 struct hostkey_sid *hks; 370 const struct sshkey *fromkey = NULL; 371 const char *test_user; 372 char *fp1, *fp2; 373 374 /* XXX remove logspam */ 375 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 376 "%zu constraints", sshkey_type(id->key), id->comment, 377 e->nsession_ids, id->ndest_constraints); 378 if (id->ndest_constraints == 0) 379 return 0; /* unconstrained */ 380 if (e->nsession_ids == 0) 381 return 0; /* local use */ 382 /* 383 * Walk through the hops recorded by session_id and try to find a 384 * constraint that satisfies each. 385 */ 386 for (i = 0; i < e->nsession_ids; i++) { 387 hks = e->session_ids + i; 388 if (hks->key == NULL) 389 fatal_f("internal error: no bound key"); 390 /* XXX remove logspam */ 391 fp1 = fp2 = NULL; 392 if (fromkey != NULL && 393 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 394 SSH_FP_DEFAULT)) == NULL) 395 fatal_f("fingerprint failed"); 396 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 397 SSH_FP_DEFAULT)) == NULL) 398 fatal_f("fingerprint failed"); 399 debug3_f("socketentry fd=%d, entry %zu %s, " 400 "from hostkey %s %s to user %s hostkey %s %s", 401 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 402 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 403 fromkey ? fp1 : "", user ? user : "(ANY)", 404 sshkey_type(hks->key), fp2); 405 free(fp1); 406 free(fp2); 407 /* 408 * Record the hostnames for the initial forwarding and 409 * the final destination. 410 */ 411 hp = NULL; 412 if (i == e->nsession_ids - 1) 413 hp = last_hostnamep; 414 else if (i == 0) 415 hp = forward_hostnamep; 416 /* Special handling for final recorded binding */ 417 test_user = NULL; 418 if (i == e->nsession_ids - 1) { 419 /* Can only check user at final hop */ 420 test_user = user; 421 /* 422 * user is only presented for signature requests. 423 * If this is the case, make sure last binding is not 424 * for a forwarding. 425 */ 426 if (hks->forwarded && user != NULL) { 427 error_f("tried to sign on forwarding hop"); 428 return -1; 429 } 430 } else if (!hks->forwarded) { 431 error_f("tried to forward though signing bind"); 432 return -1; 433 } 434 if (permitted_by_dest_constraints(fromkey, hks->key, id, 435 test_user, hp) != 0) 436 return -1; 437 fromkey = hks->key; 438 } 439 /* 440 * Another special case: if the last bound session ID was for a 441 * forwarding, and this function is not being called to check a sign 442 * request (i.e. no 'user' supplied), then only permit the key if 443 * there is a permission that would allow it to be used at another 444 * destination. This hides keys that are allowed to be used to 445 * authenticate *to* a host but not permitted for *use* beyond it. 446 */ 447 hks = &e->session_ids[e->nsession_ids - 1]; 448 if (hks->forwarded && user == NULL && 449 permitted_by_dest_constraints(hks->key, NULL, id, 450 NULL, NULL) != 0) { 451 debug3_f("key permitted at host but not after"); 452 return -1; 453 } 454 455 /* success */ 456 return 0; 457 } 458 459 /* return matching private key for given public key */ 460 static Identity * 461 lookup_identity(struct sshkey *key) 462 { 463 Identity *id; 464 465 TAILQ_FOREACH(id, &idtab->idlist, next) { 466 if (sshkey_equal(key, id->key)) 467 return (id); 468 } 469 return (NULL); 470 } 471 472 /* Check confirmation of keysign request */ 473 static int 474 confirm_key(Identity *id, const char *extra) 475 { 476 char *p; 477 int ret = -1; 478 479 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 480 if (p != NULL && 481 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 482 id->comment, p, 483 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 484 ret = 0; 485 free(p); 486 487 return (ret); 488 } 489 490 static void 491 send_status(SocketEntry *e, int success) 492 { 493 int r; 494 495 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 496 (r = sshbuf_put_u8(e->output, success ? 497 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 498 fatal_fr(r, "compose"); 499 } 500 501 /* send list of supported public keys to 'client' */ 502 static void 503 process_request_identities(SocketEntry *e) 504 { 505 Identity *id; 506 struct sshbuf *msg, *keys; 507 int r; 508 u_int nentries = 0; 509 510 debug2_f("entering"); 511 512 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 513 fatal_f("sshbuf_new failed"); 514 TAILQ_FOREACH(id, &idtab->idlist, next) { 515 /* identity not visible, don't include in response */ 516 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 517 continue; 518 if ((r = sshkey_puts_opts(id->key, keys, 519 SSHKEY_SERIALIZE_INFO)) != 0 || 520 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 521 error_fr(r, "compose key/comment"); 522 continue; 523 } 524 nentries++; 525 } 526 debug2_f("replying with %u allowed of %u available keys", 527 nentries, idtab->nentries); 528 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 529 (r = sshbuf_put_u32(msg, nentries)) != 0 || 530 (r = sshbuf_putb(msg, keys)) != 0) 531 fatal_fr(r, "compose"); 532 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 533 fatal_fr(r, "enqueue"); 534 sshbuf_free(msg); 535 sshbuf_free(keys); 536 } 537 538 539 static char * 540 agent_decode_alg(struct sshkey *key, u_int flags) 541 { 542 if (key->type == KEY_RSA) { 543 if (flags & SSH_AGENT_RSA_SHA2_256) 544 return "rsa-sha2-256"; 545 else if (flags & SSH_AGENT_RSA_SHA2_512) 546 return "rsa-sha2-512"; 547 } else if (key->type == KEY_RSA_CERT) { 548 if (flags & SSH_AGENT_RSA_SHA2_256) 549 return "rsa-sha2-256-cert-v01@openssh.com"; 550 else if (flags & SSH_AGENT_RSA_SHA2_512) 551 return "rsa-sha2-512-cert-v01@openssh.com"; 552 } 553 return NULL; 554 } 555 556 /* 557 * Attempt to parse the contents of a buffer as a SSH publickey userauth 558 * request, checking its contents for consistency and matching the embedded 559 * key against the one that is being used for signing. 560 * Note: does not modify msg buffer. 561 * Optionally extract the username, session ID and/or hostkey from the request. 562 */ 563 static int 564 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 565 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 566 { 567 struct sshbuf *b = NULL, *sess_id = NULL; 568 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 569 int r; 570 u_char t, sig_follows; 571 struct sshkey *mkey = NULL, *hostkey = NULL; 572 573 if (userp != NULL) 574 *userp = NULL; 575 if (sess_idp != NULL) 576 *sess_idp = NULL; 577 if (hostkeyp != NULL) 578 *hostkeyp = NULL; 579 if ((b = sshbuf_fromb(msg)) == NULL) 580 fatal_f("sshbuf_fromb"); 581 582 /* SSH userauth request */ 583 if ((r = sshbuf_froms(b, &sess_id)) != 0) 584 goto out; 585 if (sshbuf_len(sess_id) == 0) { 586 r = SSH_ERR_INVALID_FORMAT; 587 goto out; 588 } 589 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 590 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 591 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 592 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 593 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 594 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 595 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 596 goto out; 597 if (t != SSH2_MSG_USERAUTH_REQUEST || 598 sig_follows != 1 || 599 strcmp(service, "ssh-connection") != 0 || 600 !sshkey_equal(expected_key, mkey) || 601 sshkey_type_from_name(pkalg) != expected_key->type) { 602 r = SSH_ERR_INVALID_FORMAT; 603 goto out; 604 } 605 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 606 if ((r = sshkey_froms(b, &hostkey)) != 0) 607 goto out; 608 } else if (strcmp(method, "publickey") != 0) { 609 r = SSH_ERR_INVALID_FORMAT; 610 goto out; 611 } 612 if (sshbuf_len(b) != 0) { 613 r = SSH_ERR_INVALID_FORMAT; 614 goto out; 615 } 616 /* success */ 617 r = 0; 618 debug3_f("well formed userauth"); 619 if (userp != NULL) { 620 *userp = user; 621 user = NULL; 622 } 623 if (sess_idp != NULL) { 624 *sess_idp = sess_id; 625 sess_id = NULL; 626 } 627 if (hostkeyp != NULL) { 628 *hostkeyp = hostkey; 629 hostkey = NULL; 630 } 631 out: 632 sshbuf_free(b); 633 sshbuf_free(sess_id); 634 free(user); 635 free(service); 636 free(method); 637 free(pkalg); 638 sshkey_free(mkey); 639 sshkey_free(hostkey); 640 return r; 641 } 642 643 /* 644 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 645 * Note: does not modify buffer. 646 */ 647 static int 648 parse_sshsig_request(struct sshbuf *msg) 649 { 650 int r; 651 struct sshbuf *b; 652 653 if ((b = sshbuf_fromb(msg)) == NULL) 654 fatal_f("sshbuf_fromb"); 655 656 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 657 (r = sshbuf_consume(b, 6)) != 0 || 658 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 659 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 660 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 661 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 662 goto out; 663 if (sshbuf_len(b) != 0) { 664 r = SSH_ERR_INVALID_FORMAT; 665 goto out; 666 } 667 /* success */ 668 r = 0; 669 out: 670 sshbuf_free(b); 671 return r; 672 } 673 674 /* 675 * This function inspects a message to be signed by a FIDO key that has a 676 * web-like application string (i.e. one that does not begin with "ssh:". 677 * It checks that the message is one of those expected for SSH operations 678 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 679 * for the web. 680 */ 681 static int 682 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 683 { 684 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 685 debug_f("signed data matches public key userauth request"); 686 return 1; 687 } 688 if (parse_sshsig_request(data) == 0) { 689 debug_f("signed data matches SSHSIG signature request"); 690 return 1; 691 } 692 693 /* XXX check CA signature operation */ 694 695 error("web-origin key attempting to sign non-SSH message"); 696 return 0; 697 } 698 699 static int 700 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 701 { 702 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 703 return SSH_ERR_INVALID_ARGUMENT; 704 if (sshbuf_len(a) != sshbuf_len(b)) 705 return SSH_ERR_INVALID_FORMAT; 706 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 707 return SSH_ERR_INVALID_FORMAT; 708 return 0; 709 } 710 711 /* ssh2 only */ 712 static void 713 process_sign_request2(SocketEntry *e) 714 { 715 u_char *signature = NULL; 716 size_t slen = 0; 717 u_int compat = 0, flags; 718 int r, ok = -1, retried = 0; 719 char *fp = NULL, *pin = NULL, *prompt = NULL; 720 char *user = NULL, *sig_dest = NULL; 721 const char *fwd_host = NULL, *dest_host = NULL; 722 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 723 struct sshkey *key = NULL, *hostkey = NULL; 724 struct identity *id; 725 struct notifier_ctx *notifier = NULL; 726 727 debug_f("entering"); 728 729 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 730 fatal_f("sshbuf_new failed"); 731 if ((r = sshkey_froms(e->request, &key)) != 0 || 732 (r = sshbuf_get_stringb(e->request, data)) != 0 || 733 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 734 error_fr(r, "parse"); 735 goto send; 736 } 737 738 if ((id = lookup_identity(key)) == NULL) { 739 verbose_f("%s key not found", sshkey_type(key)); 740 goto send; 741 } 742 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 743 SSH_FP_DEFAULT)) == NULL) 744 fatal_f("fingerprint failed"); 745 746 if (id->ndest_constraints != 0) { 747 if (e->nsession_ids == 0) { 748 logit_f("refusing use of destination-constrained key " 749 "to sign on unbound connection"); 750 goto send; 751 } 752 if (parse_userauth_request(data, key, &user, &sid, 753 &hostkey) != 0) { 754 logit_f("refusing use of destination-constrained key " 755 "to sign an unidentified signature"); 756 goto send; 757 } 758 /* XXX logspam */ 759 debug_f("user=%s", user); 760 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 761 goto send; 762 /* XXX display fwd_host/dest_host in askpass UI */ 763 /* 764 * Ensure that the session ID is the most recent one 765 * registered on the socket - it should have been bound by 766 * ssh immediately before userauth. 767 */ 768 if (buf_equal(sid, 769 e->session_ids[e->nsession_ids - 1].sid) != 0) { 770 error_f("unexpected session ID (%zu listed) on " 771 "signature request for target user %s with " 772 "key %s %s", e->nsession_ids, user, 773 sshkey_type(id->key), fp); 774 goto send; 775 } 776 /* 777 * Ensure that the hostkey embedded in the signature matches 778 * the one most recently bound to the socket. An exception is 779 * made for the initial forwarding hop. 780 */ 781 if (e->nsession_ids > 1 && hostkey == NULL) { 782 error_f("refusing use of destination-constrained key: " 783 "no hostkey recorded in signature for forwarded " 784 "connection"); 785 goto send; 786 } 787 if (hostkey != NULL && !sshkey_equal(hostkey, 788 e->session_ids[e->nsession_ids - 1].key)) { 789 error_f("refusing use of destination-constrained key: " 790 "mismatch between hostkey in request and most " 791 "recently bound session"); 792 goto send; 793 } 794 xasprintf(&sig_dest, "public key authentication request for " 795 "user \"%s\" to listed host", user); 796 } 797 if (id->confirm && confirm_key(id, sig_dest) != 0) { 798 verbose_f("user refused key"); 799 goto send; 800 } 801 if (sshkey_is_sk(id->key)) { 802 if (restrict_websafe && 803 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 804 !check_websafe_message_contents(key, data)) { 805 /* error already logged */ 806 goto send; 807 } 808 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 809 notifier = notify_start(0, 810 "Confirm user presence for key %s %s%s%s", 811 sshkey_type(id->key), fp, 812 sig_dest == NULL ? "" : "\n", 813 sig_dest == NULL ? "" : sig_dest); 814 } 815 } 816 retry_pin: 817 if ((r = sshkey_sign(id->key, &signature, &slen, 818 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 819 id->sk_provider, pin, compat)) != 0) { 820 debug_fr(r, "sshkey_sign"); 821 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 822 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 823 notify_complete(notifier, NULL); 824 notifier = NULL; 825 /* XXX include sig_dest */ 826 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 827 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 828 " and confirm user presence " : " ", 829 sshkey_type(id->key), fp); 830 pin = read_passphrase(prompt, RP_USE_ASKPASS); 831 retried = 1; 832 goto retry_pin; 833 } 834 error_fr(r, "sshkey_sign"); 835 goto send; 836 } 837 /* Success */ 838 ok = 0; 839 debug_f("good signature"); 840 send: 841 notify_complete(notifier, "User presence confirmed"); 842 843 if (ok == 0) { 844 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 845 (r = sshbuf_put_string(msg, signature, slen)) != 0) 846 fatal_fr(r, "compose"); 847 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 848 fatal_fr(r, "compose failure"); 849 850 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 851 fatal_fr(r, "enqueue"); 852 853 sshbuf_free(sid); 854 sshbuf_free(data); 855 sshbuf_free(msg); 856 sshkey_free(key); 857 sshkey_free(hostkey); 858 free(fp); 859 free(signature); 860 free(sig_dest); 861 free(user); 862 free(prompt); 863 if (pin != NULL) 864 freezero(pin, strlen(pin)); 865 } 866 867 /* shared */ 868 static void 869 process_remove_identity(SocketEntry *e) 870 { 871 int r, success = 0; 872 struct sshkey *key = NULL; 873 Identity *id; 874 875 debug2_f("entering"); 876 if ((r = sshkey_froms(e->request, &key)) != 0) { 877 error_fr(r, "parse key"); 878 goto done; 879 } 880 if ((id = lookup_identity(key)) == NULL) { 881 debug_f("key not found"); 882 goto done; 883 } 884 /* identity not visible, cannot be removed */ 885 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 886 goto done; /* error already logged */ 887 /* We have this key, free it. */ 888 if (idtab->nentries < 1) 889 fatal_f("internal error: nentries %d", idtab->nentries); 890 TAILQ_REMOVE(&idtab->idlist, id, next); 891 free_identity(id); 892 idtab->nentries--; 893 success = 1; 894 done: 895 sshkey_free(key); 896 send_status(e, success); 897 } 898 899 static void 900 process_remove_all_identities(SocketEntry *e) 901 { 902 Identity *id; 903 904 debug2_f("entering"); 905 /* Loop over all identities and clear the keys. */ 906 for (id = TAILQ_FIRST(&idtab->idlist); id; 907 id = TAILQ_FIRST(&idtab->idlist)) { 908 TAILQ_REMOVE(&idtab->idlist, id, next); 909 free_identity(id); 910 } 911 912 /* Mark that there are no identities. */ 913 idtab->nentries = 0; 914 915 /* Send success. */ 916 send_status(e, 1); 917 } 918 919 /* removes expired keys and returns number of seconds until the next expiry */ 920 static time_t 921 reaper(void) 922 { 923 time_t deadline = 0, now = monotime(); 924 Identity *id, *nxt; 925 926 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 927 nxt = TAILQ_NEXT(id, next); 928 if (id->death == 0) 929 continue; 930 if (now >= id->death) { 931 debug("expiring key '%s'", id->comment); 932 TAILQ_REMOVE(&idtab->idlist, id, next); 933 free_identity(id); 934 idtab->nentries--; 935 } else 936 deadline = (deadline == 0) ? id->death : 937 MINIMUM(deadline, id->death); 938 } 939 if (deadline == 0 || deadline <= now) 940 return 0; 941 else 942 return (deadline - now); 943 } 944 945 static int 946 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 947 { 948 u_char key_is_ca; 949 size_t elen = 0; 950 int r; 951 struct sshkey *k = NULL; 952 char *fp; 953 954 memset(dch, '\0', sizeof(*dch)); 955 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 956 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 957 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 958 error_fr(r, "parse"); 959 goto out; 960 } 961 if (elen != 0) { 962 error_f("unsupported extensions (len %zu)", elen); 963 r = SSH_ERR_FEATURE_UNSUPPORTED; 964 goto out; 965 } 966 if (*dch->hostname == '\0') { 967 free(dch->hostname); 968 dch->hostname = NULL; 969 } 970 if (*dch->user == '\0') { 971 free(dch->user); 972 dch->user = NULL; 973 } 974 while (sshbuf_len(b) != 0) { 975 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 976 dch->nkeys + 1, sizeof(*dch->keys)); 977 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 978 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 979 if ((r = sshkey_froms(b, &k)) != 0 || 980 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 981 goto out; 982 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 983 SSH_FP_DEFAULT)) == NULL) 984 fatal_f("fingerprint failed"); 985 debug3_f("%s%s%s: adding %skey %s %s", 986 dch->user == NULL ? "" : dch->user, 987 dch->user == NULL ? "" : "@", 988 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 989 free(fp); 990 dch->keys[dch->nkeys] = k; 991 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 992 dch->nkeys++; 993 k = NULL; /* transferred */ 994 } 995 /* success */ 996 r = 0; 997 out: 998 sshkey_free(k); 999 return r; 1000 } 1001 1002 static int 1003 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1004 { 1005 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1006 int r; 1007 size_t elen = 0; 1008 1009 debug3_f("entering"); 1010 1011 memset(dc, '\0', sizeof(*dc)); 1012 if ((r = sshbuf_froms(m, &b)) != 0 || 1013 (r = sshbuf_froms(b, &frombuf)) != 0 || 1014 (r = sshbuf_froms(b, &tobuf)) != 0 || 1015 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1016 error_fr(r, "parse"); 1017 goto out; 1018 } 1019 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1020 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1021 goto out; /* already logged */ 1022 if (elen != 0) { 1023 error_f("unsupported extensions (len %zu)", elen); 1024 r = SSH_ERR_FEATURE_UNSUPPORTED; 1025 goto out; 1026 } 1027 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1028 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1029 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1030 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1031 /* check consistency */ 1032 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1033 dc->from.user != NULL) { 1034 error_f("inconsistent \"from\" specification"); 1035 r = SSH_ERR_INVALID_FORMAT; 1036 goto out; 1037 } 1038 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1039 error_f("incomplete \"to\" specification"); 1040 r = SSH_ERR_INVALID_FORMAT; 1041 goto out; 1042 } 1043 /* success */ 1044 r = 0; 1045 out: 1046 sshbuf_free(b); 1047 sshbuf_free(frombuf); 1048 sshbuf_free(tobuf); 1049 return r; 1050 } 1051 1052 static int 1053 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1054 struct dest_constraint **dcsp, size_t *ndcsp) 1055 { 1056 char *ext_name = NULL; 1057 int r; 1058 struct sshbuf *b = NULL; 1059 1060 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1061 error_fr(r, "parse constraint extension"); 1062 goto out; 1063 } 1064 debug_f("constraint ext %s", ext_name); 1065 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1066 if (sk_providerp == NULL) { 1067 error_f("%s not valid here", ext_name); 1068 r = SSH_ERR_INVALID_FORMAT; 1069 goto out; 1070 } 1071 if (*sk_providerp != NULL) { 1072 error_f("%s already set", ext_name); 1073 r = SSH_ERR_INVALID_FORMAT; 1074 goto out; 1075 } 1076 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1077 error_fr(r, "parse %s", ext_name); 1078 goto out; 1079 } 1080 } else if (strcmp(ext_name, 1081 "restrict-destination-v00@openssh.com") == 0) { 1082 if (*dcsp != NULL) { 1083 error_f("%s already set", ext_name); 1084 goto out; 1085 } 1086 if ((r = sshbuf_froms(m, &b)) != 0) { 1087 error_fr(r, "parse %s outer", ext_name); 1088 goto out; 1089 } 1090 while (sshbuf_len(b) != 0) { 1091 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1092 error_f("too many %s constraints", ext_name); 1093 goto out; 1094 } 1095 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1096 sizeof(**dcsp)); 1097 if ((r = parse_dest_constraint(b, 1098 *dcsp + (*ndcsp)++)) != 0) 1099 goto out; /* error already logged */ 1100 } 1101 } else { 1102 error_f("unsupported constraint \"%s\"", ext_name); 1103 r = SSH_ERR_FEATURE_UNSUPPORTED; 1104 goto out; 1105 } 1106 /* success */ 1107 r = 0; 1108 out: 1109 free(ext_name); 1110 sshbuf_free(b); 1111 return r; 1112 } 1113 1114 static int 1115 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1116 u_int *secondsp, int *confirmp, char **sk_providerp, 1117 struct dest_constraint **dcsp, size_t *ndcsp) 1118 { 1119 u_char ctype; 1120 int r; 1121 u_int seconds, maxsign = 0; 1122 1123 while (sshbuf_len(m)) { 1124 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1125 error_fr(r, "parse constraint type"); 1126 goto out; 1127 } 1128 switch (ctype) { 1129 case SSH_AGENT_CONSTRAIN_LIFETIME: 1130 if (*deathp != 0) { 1131 error_f("lifetime already set"); 1132 r = SSH_ERR_INVALID_FORMAT; 1133 goto out; 1134 } 1135 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1136 error_fr(r, "parse lifetime constraint"); 1137 goto out; 1138 } 1139 *deathp = monotime() + seconds; 1140 *secondsp = seconds; 1141 break; 1142 case SSH_AGENT_CONSTRAIN_CONFIRM: 1143 if (*confirmp != 0) { 1144 error_f("confirm already set"); 1145 r = SSH_ERR_INVALID_FORMAT; 1146 goto out; 1147 } 1148 *confirmp = 1; 1149 break; 1150 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1151 if (k == NULL) { 1152 error_f("maxsign not valid here"); 1153 r = SSH_ERR_INVALID_FORMAT; 1154 goto out; 1155 } 1156 if (maxsign != 0) { 1157 error_f("maxsign already set"); 1158 r = SSH_ERR_INVALID_FORMAT; 1159 goto out; 1160 } 1161 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1162 error_fr(r, "parse maxsign constraint"); 1163 goto out; 1164 } 1165 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1166 error_fr(r, "enable maxsign"); 1167 goto out; 1168 } 1169 break; 1170 case SSH_AGENT_CONSTRAIN_EXTENSION: 1171 if ((r = parse_key_constraint_extension(m, 1172 sk_providerp, dcsp, ndcsp)) != 0) 1173 goto out; /* error already logged */ 1174 break; 1175 default: 1176 error_f("Unknown constraint %d", ctype); 1177 r = SSH_ERR_FEATURE_UNSUPPORTED; 1178 goto out; 1179 } 1180 } 1181 /* success */ 1182 r = 0; 1183 out: 1184 return r; 1185 } 1186 1187 static void 1188 process_add_identity(SocketEntry *e) 1189 { 1190 Identity *id; 1191 int success = 0, confirm = 0; 1192 char *fp, *comment = NULL, *sk_provider = NULL; 1193 char canonical_provider[PATH_MAX]; 1194 time_t death = 0; 1195 u_int seconds = 0; 1196 struct dest_constraint *dest_constraints = NULL; 1197 size_t ndest_constraints = 0; 1198 struct sshkey *k = NULL; 1199 int r = SSH_ERR_INTERNAL_ERROR; 1200 1201 debug2_f("entering"); 1202 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1203 k == NULL || 1204 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1205 error_fr(r, "parse"); 1206 goto out; 1207 } 1208 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1209 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1210 error_f("failed to parse constraints"); 1211 sshbuf_reset(e->request); 1212 goto out; 1213 } 1214 1215 if (sk_provider != NULL) { 1216 if (!sshkey_is_sk(k)) { 1217 error("Cannot add provider: %s is not an " 1218 "authenticator-hosted key", sshkey_type(k)); 1219 goto out; 1220 } 1221 if (strcasecmp(sk_provider, "internal") == 0) { 1222 debug_f("internal provider"); 1223 } else { 1224 if (e->nsession_ids != 0 && !remote_add_provider) { 1225 verbose("failed add of SK provider \"%.100s\": " 1226 "remote addition of providers is disabled", 1227 sk_provider); 1228 goto out; 1229 } 1230 if (realpath(sk_provider, canonical_provider) == NULL) { 1231 verbose("failed provider \"%.100s\": " 1232 "realpath: %s", sk_provider, 1233 strerror(errno)); 1234 goto out; 1235 } 1236 free(sk_provider); 1237 sk_provider = xstrdup(canonical_provider); 1238 if (match_pattern_list(sk_provider, 1239 allowed_providers, 0) != 1) { 1240 error("Refusing add key: " 1241 "provider %s not allowed", sk_provider); 1242 goto out; 1243 } 1244 } 1245 } 1246 if ((r = sshkey_shield_private(k)) != 0) { 1247 error_fr(r, "shield private"); 1248 goto out; 1249 } 1250 if (lifetime && !death) 1251 death = monotime() + lifetime; 1252 if ((id = lookup_identity(k)) == NULL) { 1253 id = xcalloc(1, sizeof(Identity)); 1254 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1255 /* Increment the number of identities. */ 1256 idtab->nentries++; 1257 } else { 1258 /* identity not visible, do not update */ 1259 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1260 goto out; /* error already logged */ 1261 /* key state might have been updated */ 1262 sshkey_free(id->key); 1263 free(id->comment); 1264 free(id->sk_provider); 1265 free_dest_constraints(id->dest_constraints, 1266 id->ndest_constraints); 1267 } 1268 /* success */ 1269 id->key = k; 1270 id->comment = comment; 1271 id->death = death; 1272 id->confirm = confirm; 1273 id->sk_provider = sk_provider; 1274 id->dest_constraints = dest_constraints; 1275 id->ndest_constraints = ndest_constraints; 1276 1277 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1278 SSH_FP_DEFAULT)) == NULL) 1279 fatal_f("sshkey_fingerprint failed"); 1280 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1281 "(provider: %s) (destination constraints: %zu)", 1282 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1283 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1284 free(fp); 1285 /* transferred */ 1286 k = NULL; 1287 comment = NULL; 1288 sk_provider = NULL; 1289 dest_constraints = NULL; 1290 ndest_constraints = 0; 1291 success = 1; 1292 out: 1293 free(sk_provider); 1294 free(comment); 1295 sshkey_free(k); 1296 free_dest_constraints(dest_constraints, ndest_constraints); 1297 send_status(e, success); 1298 } 1299 1300 /* XXX todo: encrypt sensitive data with passphrase */ 1301 static void 1302 process_lock_agent(SocketEntry *e, int lock) 1303 { 1304 int r, success = 0, delay; 1305 char *passwd; 1306 u_char passwdhash[LOCK_SIZE]; 1307 static u_int fail_count = 0; 1308 size_t pwlen; 1309 1310 debug2_f("entering"); 1311 /* 1312 * This is deliberately fatal: the user has requested that we lock, 1313 * but we can't parse their request properly. The only safe thing to 1314 * do is abort. 1315 */ 1316 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1317 fatal_fr(r, "parse"); 1318 if (pwlen == 0) { 1319 debug("empty password not supported"); 1320 } else if (locked && !lock) { 1321 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1322 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1323 fatal("bcrypt_pbkdf"); 1324 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1325 debug("agent unlocked"); 1326 locked = 0; 1327 fail_count = 0; 1328 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1329 success = 1; 1330 } else { 1331 /* delay in 0.1s increments up to 10s */ 1332 if (fail_count < 100) 1333 fail_count++; 1334 delay = 100000 * fail_count; 1335 debug("unlock failed, delaying %0.1lf seconds", 1336 (double)delay/1000000); 1337 usleep(delay); 1338 } 1339 explicit_bzero(passwdhash, sizeof(passwdhash)); 1340 } else if (!locked && lock) { 1341 debug("agent locked"); 1342 locked = 1; 1343 arc4random_buf(lock_salt, sizeof(lock_salt)); 1344 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1345 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1346 fatal("bcrypt_pbkdf"); 1347 success = 1; 1348 } 1349 freezero(passwd, pwlen); 1350 send_status(e, success); 1351 } 1352 1353 static void 1354 no_identities(SocketEntry *e) 1355 { 1356 struct sshbuf *msg; 1357 int r; 1358 1359 if ((msg = sshbuf_new()) == NULL) 1360 fatal_f("sshbuf_new failed"); 1361 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1362 (r = sshbuf_put_u32(msg, 0)) != 0 || 1363 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1364 fatal_fr(r, "compose"); 1365 sshbuf_free(msg); 1366 } 1367 1368 #ifdef ENABLE_PKCS11 1369 static void 1370 process_add_smartcard_key(SocketEntry *e) 1371 { 1372 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1373 char **comments = NULL; 1374 int r, i, count = 0, success = 0, confirm = 0; 1375 u_int seconds = 0; 1376 time_t death = 0; 1377 struct sshkey **keys = NULL, *k; 1378 Identity *id; 1379 struct dest_constraint *dest_constraints = NULL; 1380 size_t ndest_constraints = 0; 1381 1382 debug2_f("entering"); 1383 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1384 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1385 error_fr(r, "parse"); 1386 goto send; 1387 } 1388 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1389 NULL, &dest_constraints, &ndest_constraints) != 0) { 1390 error_f("failed to parse constraints"); 1391 goto send; 1392 } 1393 if (e->nsession_ids != 0 && !remote_add_provider) { 1394 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1395 "providers is disabled", provider); 1396 goto send; 1397 } 1398 if (realpath(provider, canonical_provider) == NULL) { 1399 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1400 provider, strerror(errno)); 1401 goto send; 1402 } 1403 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1404 verbose("refusing PKCS#11 add of \"%.100s\": " 1405 "provider not allowed", canonical_provider); 1406 goto send; 1407 } 1408 debug_f("add %.100s", canonical_provider); 1409 if (lifetime && !death) 1410 death = monotime() + lifetime; 1411 1412 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1413 for (i = 0; i < count; i++) { 1414 k = keys[i]; 1415 if (lookup_identity(k) == NULL) { 1416 id = xcalloc(1, sizeof(Identity)); 1417 id->key = k; 1418 keys[i] = NULL; /* transferred */ 1419 id->provider = xstrdup(canonical_provider); 1420 if (*comments[i] != '\0') { 1421 id->comment = comments[i]; 1422 comments[i] = NULL; /* transferred */ 1423 } else { 1424 id->comment = xstrdup(canonical_provider); 1425 } 1426 id->death = death; 1427 id->confirm = confirm; 1428 id->dest_constraints = dest_constraints; 1429 id->ndest_constraints = ndest_constraints; 1430 dest_constraints = NULL; /* transferred */ 1431 ndest_constraints = 0; 1432 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1433 idtab->nentries++; 1434 success = 1; 1435 } 1436 /* XXX update constraints for existing keys */ 1437 sshkey_free(keys[i]); 1438 free(comments[i]); 1439 } 1440 send: 1441 free(pin); 1442 free(provider); 1443 free(keys); 1444 free(comments); 1445 free_dest_constraints(dest_constraints, ndest_constraints); 1446 send_status(e, success); 1447 } 1448 1449 static void 1450 process_remove_smartcard_key(SocketEntry *e) 1451 { 1452 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1453 int r, success = 0; 1454 Identity *id, *nxt; 1455 1456 debug2_f("entering"); 1457 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1458 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1459 error_fr(r, "parse"); 1460 goto send; 1461 } 1462 free(pin); 1463 1464 if (realpath(provider, canonical_provider) == NULL) { 1465 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1466 provider, strerror(errno)); 1467 goto send; 1468 } 1469 1470 debug_f("remove %.100s", canonical_provider); 1471 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1472 nxt = TAILQ_NEXT(id, next); 1473 /* Skip file--based keys */ 1474 if (id->provider == NULL) 1475 continue; 1476 if (!strcmp(canonical_provider, id->provider)) { 1477 TAILQ_REMOVE(&idtab->idlist, id, next); 1478 free_identity(id); 1479 idtab->nentries--; 1480 } 1481 } 1482 if (pkcs11_del_provider(canonical_provider) == 0) 1483 success = 1; 1484 else 1485 error_f("pkcs11_del_provider failed"); 1486 send: 1487 free(provider); 1488 send_status(e, success); 1489 } 1490 #endif /* ENABLE_PKCS11 */ 1491 1492 static int 1493 process_ext_session_bind(SocketEntry *e) 1494 { 1495 int r, sid_match, key_match; 1496 struct sshkey *key = NULL; 1497 struct sshbuf *sid = NULL, *sig = NULL; 1498 char *fp = NULL; 1499 size_t i; 1500 u_char fwd = 0; 1501 1502 debug2_f("entering"); 1503 if ((r = sshkey_froms(e->request, &key)) != 0 || 1504 (r = sshbuf_froms(e->request, &sid)) != 0 || 1505 (r = sshbuf_froms(e->request, &sig)) != 0 || 1506 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1507 error_fr(r, "parse"); 1508 goto out; 1509 } 1510 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1511 SSH_FP_DEFAULT)) == NULL) 1512 fatal_f("fingerprint failed"); 1513 /* check signature with hostkey on session ID */ 1514 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1515 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1516 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1517 goto out; 1518 } 1519 /* check whether sid/key already recorded */ 1520 for (i = 0; i < e->nsession_ids; i++) { 1521 if (!e->session_ids[i].forwarded) { 1522 error_f("attempt to bind session ID to socket " 1523 "previously bound for authentication attempt"); 1524 r = -1; 1525 goto out; 1526 } 1527 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1528 key_match = sshkey_equal(key, e->session_ids[i].key); 1529 if (sid_match && key_match) { 1530 debug_f("session ID already recorded for %s %s", 1531 sshkey_type(key), fp); 1532 r = 0; 1533 goto out; 1534 } else if (sid_match) { 1535 error_f("session ID recorded against different key " 1536 "for %s %s", sshkey_type(key), fp); 1537 r = -1; 1538 goto out; 1539 } 1540 /* 1541 * new sid with previously-seen key can happen, e.g. multiple 1542 * connections to the same host. 1543 */ 1544 } 1545 /* record new key/sid */ 1546 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1547 error_f("too many session IDs recorded"); 1548 goto out; 1549 } 1550 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1551 e->nsession_ids + 1, sizeof(*e->session_ids)); 1552 i = e->nsession_ids++; 1553 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1554 AGENT_MAX_SESSION_IDS); 1555 e->session_ids[i].key = key; 1556 e->session_ids[i].forwarded = fwd != 0; 1557 key = NULL; /* transferred */ 1558 /* can't transfer sid; it's refcounted and scoped to request's life */ 1559 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1560 fatal_f("sshbuf_new"); 1561 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1562 fatal_fr(r, "sshbuf_putb session ID"); 1563 /* success */ 1564 r = 0; 1565 out: 1566 free(fp); 1567 sshkey_free(key); 1568 sshbuf_free(sid); 1569 sshbuf_free(sig); 1570 return r == 0 ? 1 : 0; 1571 } 1572 1573 static void 1574 process_extension(SocketEntry *e) 1575 { 1576 int r, success = 0; 1577 char *name; 1578 1579 debug2_f("entering"); 1580 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1581 error_fr(r, "parse"); 1582 goto send; 1583 } 1584 if (strcmp(name, "session-bind@openssh.com") == 0) 1585 success = process_ext_session_bind(e); 1586 else 1587 debug_f("unsupported extension \"%s\"", name); 1588 free(name); 1589 send: 1590 send_status(e, success); 1591 } 1592 /* 1593 * dispatch incoming message. 1594 * returns 1 on success, 0 for incomplete messages or -1 on error. 1595 */ 1596 static int 1597 process_message(u_int socknum) 1598 { 1599 u_int msg_len; 1600 u_char type; 1601 const u_char *cp; 1602 int r; 1603 SocketEntry *e; 1604 1605 if (socknum >= sockets_alloc) 1606 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1607 e = &sockets[socknum]; 1608 1609 if (sshbuf_len(e->input) < 5) 1610 return 0; /* Incomplete message header. */ 1611 cp = sshbuf_ptr(e->input); 1612 msg_len = PEEK_U32(cp); 1613 if (msg_len > AGENT_MAX_LEN) { 1614 debug_f("socket %u (fd=%d) message too long %u > %u", 1615 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1616 return -1; 1617 } 1618 if (sshbuf_len(e->input) < msg_len + 4) 1619 return 0; /* Incomplete message body. */ 1620 1621 /* move the current input to e->request */ 1622 sshbuf_reset(e->request); 1623 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1624 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1625 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1626 r == SSH_ERR_STRING_TOO_LARGE) { 1627 error_fr(r, "parse"); 1628 return -1; 1629 } 1630 fatal_fr(r, "parse"); 1631 } 1632 1633 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1634 1635 /* check whether agent is locked */ 1636 if (locked && type != SSH_AGENTC_UNLOCK) { 1637 sshbuf_reset(e->request); 1638 switch (type) { 1639 case SSH2_AGENTC_REQUEST_IDENTITIES: 1640 /* send empty lists */ 1641 no_identities(e); 1642 break; 1643 default: 1644 /* send a fail message for all other request types */ 1645 send_status(e, 0); 1646 } 1647 return 1; 1648 } 1649 1650 switch (type) { 1651 case SSH_AGENTC_LOCK: 1652 case SSH_AGENTC_UNLOCK: 1653 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1654 break; 1655 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1656 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1657 break; 1658 /* ssh2 */ 1659 case SSH2_AGENTC_SIGN_REQUEST: 1660 process_sign_request2(e); 1661 break; 1662 case SSH2_AGENTC_REQUEST_IDENTITIES: 1663 process_request_identities(e); 1664 break; 1665 case SSH2_AGENTC_ADD_IDENTITY: 1666 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1667 process_add_identity(e); 1668 break; 1669 case SSH2_AGENTC_REMOVE_IDENTITY: 1670 process_remove_identity(e); 1671 break; 1672 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1673 process_remove_all_identities(e); 1674 break; 1675 #ifdef ENABLE_PKCS11 1676 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1677 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1678 process_add_smartcard_key(e); 1679 break; 1680 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1681 process_remove_smartcard_key(e); 1682 break; 1683 #endif /* ENABLE_PKCS11 */ 1684 case SSH_AGENTC_EXTENSION: 1685 process_extension(e); 1686 break; 1687 default: 1688 /* Unknown message. Respond with failure. */ 1689 error("Unknown message %d", type); 1690 sshbuf_reset(e->request); 1691 send_status(e, 0); 1692 break; 1693 } 1694 return 1; 1695 } 1696 1697 static void 1698 new_socket(sock_type type, int fd) 1699 { 1700 u_int i, old_alloc, new_alloc; 1701 1702 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1703 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1704 set_nonblock(fd); 1705 1706 if (fd > max_fd) 1707 max_fd = fd; 1708 1709 for (i = 0; i < sockets_alloc; i++) 1710 if (sockets[i].type == AUTH_UNUSED) { 1711 sockets[i].fd = fd; 1712 if ((sockets[i].input = sshbuf_new()) == NULL || 1713 (sockets[i].output = sshbuf_new()) == NULL || 1714 (sockets[i].request = sshbuf_new()) == NULL) 1715 fatal_f("sshbuf_new failed"); 1716 sockets[i].type = type; 1717 return; 1718 } 1719 old_alloc = sockets_alloc; 1720 new_alloc = sockets_alloc + 10; 1721 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1722 sizeof(sockets[0])); 1723 for (i = old_alloc; i < new_alloc; i++) 1724 sockets[i].type = AUTH_UNUSED; 1725 sockets_alloc = new_alloc; 1726 sockets[old_alloc].fd = fd; 1727 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1728 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1729 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1730 fatal_f("sshbuf_new failed"); 1731 sockets[old_alloc].type = type; 1732 } 1733 1734 static int 1735 handle_socket_read(u_int socknum) 1736 { 1737 struct sockaddr_un sunaddr; 1738 socklen_t slen; 1739 uid_t euid; 1740 gid_t egid; 1741 int fd; 1742 1743 slen = sizeof(sunaddr); 1744 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1745 if (fd == -1) { 1746 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1747 return -1; 1748 } 1749 if (getpeereid(fd, &euid, &egid) == -1) { 1750 error("getpeereid %d failed: %s", fd, strerror(errno)); 1751 close(fd); 1752 return -1; 1753 } 1754 if ((euid != 0) && (getuid() != euid)) { 1755 error("uid mismatch: peer euid %u != uid %u", 1756 (u_int) euid, (u_int) getuid()); 1757 close(fd); 1758 return -1; 1759 } 1760 new_socket(AUTH_CONNECTION, fd); 1761 return 0; 1762 } 1763 1764 static int 1765 handle_conn_read(u_int socknum) 1766 { 1767 char buf[AGENT_RBUF_LEN]; 1768 ssize_t len; 1769 int r; 1770 1771 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1772 if (len == -1) { 1773 if (errno == EAGAIN || errno == EINTR) 1774 return 0; 1775 error_f("read error on socket %u (fd %d): %s", 1776 socknum, sockets[socknum].fd, strerror(errno)); 1777 } 1778 return -1; 1779 } 1780 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1781 fatal_fr(r, "compose"); 1782 explicit_bzero(buf, sizeof(buf)); 1783 for (;;) { 1784 if ((r = process_message(socknum)) == -1) 1785 return -1; 1786 else if (r == 0) 1787 break; 1788 } 1789 return 0; 1790 } 1791 1792 static int 1793 handle_conn_write(u_int socknum) 1794 { 1795 ssize_t len; 1796 int r; 1797 1798 if (sshbuf_len(sockets[socknum].output) == 0) 1799 return 0; /* shouldn't happen */ 1800 if ((len = write(sockets[socknum].fd, 1801 sshbuf_ptr(sockets[socknum].output), 1802 sshbuf_len(sockets[socknum].output))) <= 0) { 1803 if (len == -1) { 1804 if (errno == EAGAIN || errno == EINTR) 1805 return 0; 1806 error_f("read error on socket %u (fd %d): %s", 1807 socknum, sockets[socknum].fd, strerror(errno)); 1808 } 1809 return -1; 1810 } 1811 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1812 fatal_fr(r, "consume"); 1813 return 0; 1814 } 1815 1816 static void 1817 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1818 { 1819 size_t i; 1820 u_int socknum, activefds = npfd; 1821 1822 for (i = 0; i < npfd; i++) { 1823 if (pfd[i].revents == 0) 1824 continue; 1825 /* Find sockets entry */ 1826 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1827 if (sockets[socknum].type != AUTH_SOCKET && 1828 sockets[socknum].type != AUTH_CONNECTION) 1829 continue; 1830 if (pfd[i].fd == sockets[socknum].fd) 1831 break; 1832 } 1833 if (socknum >= sockets_alloc) { 1834 error_f("no socket for fd %d", pfd[i].fd); 1835 continue; 1836 } 1837 /* Process events */ 1838 switch (sockets[socknum].type) { 1839 case AUTH_SOCKET: 1840 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1841 break; 1842 if (npfd > maxfds) { 1843 debug3("out of fds (active %u >= limit %u); " 1844 "skipping accept", activefds, maxfds); 1845 break; 1846 } 1847 if (handle_socket_read(socknum) == 0) 1848 activefds++; 1849 break; 1850 case AUTH_CONNECTION: 1851 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1852 handle_conn_read(socknum) != 0) 1853 goto close_sock; 1854 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1855 handle_conn_write(socknum) != 0) { 1856 close_sock: 1857 if (activefds == 0) 1858 fatal("activefds == 0 at close_sock"); 1859 close_socket(&sockets[socknum]); 1860 activefds--; 1861 break; 1862 } 1863 break; 1864 default: 1865 break; 1866 } 1867 } 1868 } 1869 1870 static int 1871 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1872 { 1873 struct pollfd *pfd = *pfdp; 1874 size_t i, j, npfd = 0; 1875 time_t deadline; 1876 int r; 1877 1878 /* Count active sockets */ 1879 for (i = 0; i < sockets_alloc; i++) { 1880 switch (sockets[i].type) { 1881 case AUTH_SOCKET: 1882 case AUTH_CONNECTION: 1883 npfd++; 1884 break; 1885 case AUTH_UNUSED: 1886 break; 1887 default: 1888 fatal("Unknown socket type %d", sockets[i].type); 1889 break; 1890 } 1891 } 1892 if (npfd != *npfdp && 1893 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1894 fatal_f("recallocarray failed"); 1895 *pfdp = pfd; 1896 *npfdp = npfd; 1897 1898 for (i = j = 0; i < sockets_alloc; i++) { 1899 switch (sockets[i].type) { 1900 case AUTH_SOCKET: 1901 if (npfd > maxfds) { 1902 debug3("out of fds (active %zu >= limit %u); " 1903 "skipping arming listener", npfd, maxfds); 1904 break; 1905 } 1906 pfd[j].fd = sockets[i].fd; 1907 pfd[j].revents = 0; 1908 pfd[j].events = POLLIN; 1909 j++; 1910 break; 1911 case AUTH_CONNECTION: 1912 pfd[j].fd = sockets[i].fd; 1913 pfd[j].revents = 0; 1914 /* 1915 * Only prepare to read if we can handle a full-size 1916 * input read buffer and enqueue a max size reply.. 1917 */ 1918 if ((r = sshbuf_check_reserve(sockets[i].input, 1919 AGENT_RBUF_LEN)) == 0 && 1920 (r = sshbuf_check_reserve(sockets[i].output, 1921 AGENT_MAX_LEN)) == 0) 1922 pfd[j].events = POLLIN; 1923 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1924 fatal_fr(r, "reserve"); 1925 if (sshbuf_len(sockets[i].output) > 0) 1926 pfd[j].events |= POLLOUT; 1927 j++; 1928 break; 1929 default: 1930 break; 1931 } 1932 } 1933 deadline = reaper(); 1934 if (parent_alive_interval != 0) 1935 deadline = (deadline == 0) ? parent_alive_interval : 1936 MINIMUM(deadline, parent_alive_interval); 1937 if (deadline == 0) { 1938 *timeoutp = -1; /* INFTIM */ 1939 } else { 1940 if (deadline > INT_MAX / 1000) 1941 *timeoutp = INT_MAX / 1000; 1942 else 1943 *timeoutp = deadline * 1000; 1944 } 1945 return (1); 1946 } 1947 1948 static void 1949 cleanup_socket(void) 1950 { 1951 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1952 return; 1953 debug_f("cleanup"); 1954 if (socket_name[0]) 1955 unlink(socket_name); 1956 if (socket_dir[0]) 1957 rmdir(socket_dir); 1958 } 1959 1960 void 1961 cleanup_exit(int i) 1962 { 1963 cleanup_socket(); 1964 _exit(i); 1965 } 1966 1967 static void 1968 cleanup_handler(int sig) 1969 { 1970 cleanup_socket(); 1971 #ifdef ENABLE_PKCS11 1972 pkcs11_terminate(); 1973 #endif 1974 _exit(2); 1975 } 1976 1977 static void 1978 check_parent_exists(void) 1979 { 1980 /* 1981 * If our parent has exited then getppid() will return (pid_t)1, 1982 * so testing for that should be safe. 1983 */ 1984 if (parent_pid != -1 && getppid() != parent_pid) { 1985 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1986 cleanup_socket(); 1987 _exit(2); 1988 } 1989 } 1990 1991 static void 1992 usage(void) 1993 { 1994 fprintf(stderr, 1995 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1996 " [-O option] [-P allowed_providers] [-t life]\n" 1997 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 1998 " [-P allowed_providers] [-t life] command [arg ...]\n" 1999 " ssh-agent [-c | -s] -k\n"); 2000 exit(1); 2001 } 2002 2003 int 2004 main(int ac, char **av) 2005 { 2006 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2007 int sock, ch, result, saved_errno; 2008 char *shell, *format, *pidstr, *agentsocket = NULL; 2009 struct rlimit rlim; 2010 extern int optind; 2011 extern char *optarg; 2012 pid_t pid; 2013 char pidstrbuf[1 + 3 * sizeof pid]; 2014 size_t len; 2015 mode_t prev_mask; 2016 int timeout = -1; /* INFTIM */ 2017 struct pollfd *pfd = NULL; 2018 size_t npfd = 0; 2019 u_int maxfds; 2020 2021 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2022 sanitise_stdfd(); 2023 2024 /* drop */ 2025 (void)setegid(getgid()); 2026 (void)setgid(getgid()); 2027 2028 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2029 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2030 2031 #ifdef WITH_OPENSSL 2032 OpenSSL_add_all_algorithms(); 2033 #endif 2034 2035 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2036 switch (ch) { 2037 case 'E': 2038 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2039 if (fingerprint_hash == -1) 2040 fatal("Invalid hash algorithm \"%s\"", optarg); 2041 break; 2042 case 'c': 2043 if (s_flag) 2044 usage(); 2045 c_flag++; 2046 break; 2047 case 'k': 2048 k_flag++; 2049 break; 2050 case 'O': 2051 if (strcmp(optarg, "no-restrict-websafe") == 0) 2052 restrict_websafe = 0; 2053 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2054 remote_add_provider = 1; 2055 else 2056 fatal("Unknown -O option"); 2057 break; 2058 case 'P': 2059 if (allowed_providers != NULL) 2060 fatal("-P option already specified"); 2061 allowed_providers = xstrdup(optarg); 2062 break; 2063 case 's': 2064 if (c_flag) 2065 usage(); 2066 s_flag++; 2067 break; 2068 case 'd': 2069 if (d_flag || D_flag) 2070 usage(); 2071 d_flag++; 2072 break; 2073 case 'D': 2074 if (d_flag || D_flag) 2075 usage(); 2076 D_flag++; 2077 break; 2078 case 'a': 2079 agentsocket = optarg; 2080 break; 2081 case 't': 2082 if ((lifetime = convtime(optarg)) == -1) { 2083 fprintf(stderr, "Invalid lifetime\n"); 2084 usage(); 2085 } 2086 break; 2087 default: 2088 usage(); 2089 } 2090 } 2091 ac -= optind; 2092 av += optind; 2093 2094 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2095 usage(); 2096 2097 if (allowed_providers == NULL) 2098 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2099 2100 if (ac == 0 && !c_flag && !s_flag) { 2101 shell = getenv("SHELL"); 2102 if (shell != NULL && (len = strlen(shell)) > 2 && 2103 strncmp(shell + len - 3, "csh", 3) == 0) 2104 c_flag = 1; 2105 } 2106 if (k_flag) { 2107 const char *errstr = NULL; 2108 2109 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2110 if (pidstr == NULL) { 2111 fprintf(stderr, "%s not set, cannot kill agent\n", 2112 SSH_AGENTPID_ENV_NAME); 2113 exit(1); 2114 } 2115 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2116 if (errstr) { 2117 fprintf(stderr, 2118 "%s=\"%s\", which is not a good PID: %s\n", 2119 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2120 exit(1); 2121 } 2122 if (kill(pid, SIGTERM) == -1) { 2123 perror("kill"); 2124 exit(1); 2125 } 2126 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2127 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2128 printf(format, SSH_AGENTPID_ENV_NAME); 2129 printf("echo Agent pid %ld killed;\n", (long)pid); 2130 exit(0); 2131 } 2132 2133 /* 2134 * Minimum file descriptors: 2135 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2136 * a few spare for libc / stack protectors / sanitisers, etc. 2137 */ 2138 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2139 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2140 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2141 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2142 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2143 2144 parent_pid = getpid(); 2145 2146 if (agentsocket == NULL) { 2147 /* Create private directory for agent socket */ 2148 mktemp_proto(socket_dir, sizeof(socket_dir)); 2149 if (mkdtemp(socket_dir) == NULL) { 2150 perror("mkdtemp: private socket dir"); 2151 exit(1); 2152 } 2153 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2154 (long)parent_pid); 2155 } else { 2156 /* Try to use specified agent socket */ 2157 socket_dir[0] = '\0'; 2158 strlcpy(socket_name, agentsocket, sizeof socket_name); 2159 } 2160 2161 /* 2162 * Create socket early so it will exist before command gets run from 2163 * the parent. 2164 */ 2165 prev_mask = umask(0177); 2166 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2167 if (sock < 0) { 2168 /* XXX - unix_listener() calls error() not perror() */ 2169 *socket_name = '\0'; /* Don't unlink any existing file */ 2170 cleanup_exit(1); 2171 } 2172 umask(prev_mask); 2173 2174 /* 2175 * Fork, and have the parent execute the command, if any, or present 2176 * the socket data. The child continues as the authentication agent. 2177 */ 2178 if (D_flag || d_flag) { 2179 log_init(__progname, 2180 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2181 SYSLOG_FACILITY_AUTH, 1); 2182 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2183 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2184 SSH_AUTHSOCKET_ENV_NAME); 2185 printf("echo Agent pid %ld;\n", (long)parent_pid); 2186 fflush(stdout); 2187 goto skip; 2188 } 2189 pid = fork(); 2190 if (pid == -1) { 2191 perror("fork"); 2192 cleanup_exit(1); 2193 } 2194 if (pid != 0) { /* Parent - execute the given command. */ 2195 close(sock); 2196 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2197 if (ac == 0) { 2198 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2199 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2200 SSH_AUTHSOCKET_ENV_NAME); 2201 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2202 SSH_AGENTPID_ENV_NAME); 2203 printf("echo Agent pid %ld;\n", (long)pid); 2204 exit(0); 2205 } 2206 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2207 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2208 perror("setenv"); 2209 exit(1); 2210 } 2211 execvp(av[0], av); 2212 perror(av[0]); 2213 exit(1); 2214 } 2215 /* child */ 2216 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2217 2218 if (setsid() == -1) { 2219 error("setsid: %s", strerror(errno)); 2220 cleanup_exit(1); 2221 } 2222 2223 (void)chdir("/"); 2224 if (stdfd_devnull(1, 1, 1) == -1) 2225 error_f("stdfd_devnull failed"); 2226 2227 /* deny core dumps, since memory contains unencrypted private keys */ 2228 rlim.rlim_cur = rlim.rlim_max = 0; 2229 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2230 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2231 cleanup_exit(1); 2232 } 2233 2234 skip: 2235 2236 cleanup_pid = getpid(); 2237 2238 #ifdef ENABLE_PKCS11 2239 pkcs11_init(0); 2240 #endif 2241 new_socket(AUTH_SOCKET, sock); 2242 if (ac > 0) 2243 parent_alive_interval = 10; 2244 idtab_init(); 2245 ssh_signal(SIGPIPE, SIG_IGN); 2246 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2247 ssh_signal(SIGHUP, cleanup_handler); 2248 ssh_signal(SIGTERM, cleanup_handler); 2249 2250 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2251 fatal("%s: pledge: %s", __progname, strerror(errno)); 2252 2253 while (1) { 2254 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2255 result = poll(pfd, npfd, timeout); 2256 saved_errno = errno; 2257 if (parent_alive_interval != 0) 2258 check_parent_exists(); 2259 (void) reaper(); /* remove expired keys */ 2260 if (result == -1) { 2261 if (saved_errno == EINTR) 2262 continue; 2263 fatal("poll: %s", strerror(saved_errno)); 2264 } else if (result > 0) 2265 after_poll(pfd, npfd, maxfds); 2266 } 2267 /* NOTREACHED */ 2268 } 2269