1 /* $OpenBSD: ssh-agent.c,v 1.292 2022/09/17 10:11:29 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 "includes.h" 38 39 #include <sys/types.h> 40 #include <sys/resource.h> 41 #include <sys/stat.h> 42 #include <sys/socket.h> 43 #include <sys/wait.h> 44 #ifdef HAVE_SYS_TIME_H 45 # include <sys/time.h> 46 #endif 47 #ifdef HAVE_SYS_UN_H 48 # include <sys/un.h> 49 #endif 50 #include "openbsd-compat/sys-queue.h" 51 52 #ifdef WITH_OPENSSL 53 #include <openssl/evp.h> 54 #include "openbsd-compat/openssl-compat.h" 55 #endif 56 57 #include <errno.h> 58 #include <fcntl.h> 59 #include <limits.h> 60 #ifdef HAVE_PATHS_H 61 # include <paths.h> 62 #endif 63 #ifdef HAVE_POLL_H 64 # include <poll.h> 65 #endif 66 #include <signal.h> 67 #include <stdarg.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <time.h> 71 #include <string.h> 72 #include <unistd.h> 73 #ifdef HAVE_UTIL_H 74 # include <util.h> 75 #endif 76 77 #include "xmalloc.h" 78 #include "ssh.h" 79 #include "ssh2.h" 80 #include "sshbuf.h" 81 #include "sshkey.h" 82 #include "authfd.h" 83 #include "compat.h" 84 #include "log.h" 85 #include "misc.h" 86 #include "digest.h" 87 #include "ssherr.h" 88 #include "match.h" 89 #include "msg.h" 90 #include "ssherr.h" 91 #include "pathnames.h" 92 #include "ssh-pkcs11.h" 93 #include "sk-api.h" 94 #include "myproposal.h" 95 96 #ifndef DEFAULT_ALLOWED_PROVIDERS 97 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 98 #endif 99 100 /* Maximum accepted message length */ 101 #define AGENT_MAX_LEN (256*1024) 102 /* Maximum bytes to read from client socket */ 103 #define AGENT_RBUF_LEN (4096) 104 /* Maximum number of recorded session IDs/hostkeys per connection */ 105 #define AGENT_MAX_SESSION_IDS 16 106 /* Maximum size of session ID */ 107 #define AGENT_MAX_SID_LEN 128 108 /* Maximum number of destination constraints to accept on a key */ 109 #define AGENT_MAX_DEST_CONSTRAINTS 1024 110 111 /* XXX store hostkey_sid in a refcounted tree */ 112 113 typedef enum { 114 AUTH_UNUSED = 0, 115 AUTH_SOCKET = 1, 116 AUTH_CONNECTION = 2, 117 } sock_type; 118 119 struct hostkey_sid { 120 struct sshkey *key; 121 struct sshbuf *sid; 122 int forwarded; 123 }; 124 125 typedef struct socket_entry { 126 int fd; 127 sock_type type; 128 struct sshbuf *input; 129 struct sshbuf *output; 130 struct sshbuf *request; 131 size_t nsession_ids; 132 struct hostkey_sid *session_ids; 133 } SocketEntry; 134 135 u_int sockets_alloc = 0; 136 SocketEntry *sockets = NULL; 137 138 typedef struct identity { 139 TAILQ_ENTRY(identity) next; 140 struct sshkey *key; 141 char *comment; 142 char *provider; 143 time_t death; 144 u_int confirm; 145 char *sk_provider; 146 struct dest_constraint *dest_constraints; 147 size_t ndest_constraints; 148 } Identity; 149 150 struct idtable { 151 int nentries; 152 TAILQ_HEAD(idqueue, identity) idlist; 153 }; 154 155 /* private key table */ 156 struct idtable *idtab; 157 158 int max_fd = 0; 159 160 /* pid of shell == parent of agent */ 161 pid_t parent_pid = -1; 162 time_t parent_alive_interval = 0; 163 164 /* pid of process for which cleanup_socket is applicable */ 165 pid_t cleanup_pid = 0; 166 167 /* pathname and directory for AUTH_SOCKET */ 168 char socket_name[PATH_MAX]; 169 char socket_dir[PATH_MAX]; 170 171 /* Pattern-list of allowed PKCS#11/Security key paths */ 172 static char *allowed_providers; 173 174 /* locking */ 175 #define LOCK_SIZE 32 176 #define LOCK_SALT_SIZE 16 177 #define LOCK_ROUNDS 1 178 int locked = 0; 179 u_char lock_pwhash[LOCK_SIZE]; 180 u_char lock_salt[LOCK_SALT_SIZE]; 181 182 extern char *__progname; 183 184 /* Default lifetime in seconds (0 == forever) */ 185 static int lifetime = 0; 186 187 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 188 189 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 190 static int restrict_websafe = 1; 191 192 static void 193 close_socket(SocketEntry *e) 194 { 195 size_t i; 196 197 close(e->fd); 198 sshbuf_free(e->input); 199 sshbuf_free(e->output); 200 sshbuf_free(e->request); 201 for (i = 0; i < e->nsession_ids; i++) { 202 sshkey_free(e->session_ids[i].key); 203 sshbuf_free(e->session_ids[i].sid); 204 } 205 free(e->session_ids); 206 memset(e, '\0', sizeof(*e)); 207 e->fd = -1; 208 e->type = AUTH_UNUSED; 209 } 210 211 static void 212 idtab_init(void) 213 { 214 idtab = xcalloc(1, sizeof(*idtab)); 215 TAILQ_INIT(&idtab->idlist); 216 idtab->nentries = 0; 217 } 218 219 static void 220 free_dest_constraint_hop(struct dest_constraint_hop *dch) 221 { 222 u_int i; 223 224 if (dch == NULL) 225 return; 226 free(dch->user); 227 free(dch->hostname); 228 for (i = 0; i < dch->nkeys; i++) 229 sshkey_free(dch->keys[i]); 230 free(dch->keys); 231 free(dch->key_is_ca); 232 } 233 234 static void 235 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 236 { 237 size_t i; 238 239 for (i = 0; i < ndcs; i++) { 240 free_dest_constraint_hop(&dcs[i].from); 241 free_dest_constraint_hop(&dcs[i].to); 242 } 243 free(dcs); 244 } 245 246 static void 247 free_identity(Identity *id) 248 { 249 sshkey_free(id->key); 250 free(id->provider); 251 free(id->comment); 252 free(id->sk_provider); 253 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 254 free(id); 255 } 256 257 /* 258 * Match 'key' against the key/CA list in a destination constraint hop 259 * Returns 0 on success or -1 otherwise. 260 */ 261 static int 262 match_key_hop(const char *tag, const struct sshkey *key, 263 const struct dest_constraint_hop *dch) 264 { 265 const char *reason = NULL; 266 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 267 u_int i; 268 char *fp; 269 270 if (key == NULL) 271 return -1; 272 /* XXX logspam */ 273 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 274 SSH_FP_DEFAULT)) == NULL) 275 fatal_f("fingerprint failed"); 276 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 277 tag, hostname, sshkey_type(key), fp, dch->nkeys); 278 free(fp); 279 for (i = 0; i < dch->nkeys; i++) { 280 if (dch->keys[i] == NULL) 281 return -1; 282 /* XXX logspam */ 283 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 284 SSH_FP_DEFAULT)) == NULL) 285 fatal_f("fingerprint failed"); 286 debug3_f("%s: key %u: %s%s %s", tag, i, 287 dch->key_is_ca[i] ? "CA " : "", 288 sshkey_type(dch->keys[i]), fp); 289 free(fp); 290 if (!sshkey_is_cert(key)) { 291 /* plain key */ 292 if (dch->key_is_ca[i] || 293 !sshkey_equal(key, dch->keys[i])) 294 continue; 295 return 0; 296 } 297 /* certificate */ 298 if (!dch->key_is_ca[i]) 299 continue; 300 if (key->cert == NULL || key->cert->signature_key == NULL) 301 return -1; /* shouldn't happen */ 302 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 303 continue; 304 if (sshkey_cert_check_host(key, hostname, 1, 305 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 306 debug_f("cert %s / hostname %s rejected: %s", 307 key->cert->key_id, hostname, reason); 308 continue; 309 } 310 return 0; 311 } 312 return -1; 313 } 314 315 /* Check destination constraints on an identity against the hostkey/user */ 316 static int 317 permitted_by_dest_constraints(const struct sshkey *fromkey, 318 const struct sshkey *tokey, Identity *id, const char *user, 319 const char **hostnamep) 320 { 321 size_t i; 322 struct dest_constraint *d; 323 324 if (hostnamep != NULL) 325 *hostnamep = NULL; 326 for (i = 0; i < id->ndest_constraints; i++) { 327 d = id->dest_constraints + i; 328 /* XXX remove logspam */ 329 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 330 i, d->from.user ? d->from.user : "", 331 d->from.user ? "@" : "", 332 d->from.hostname ? d->from.hostname : "(ORIGIN)", 333 d->from.nkeys, 334 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 335 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 336 337 /* Match 'from' key */ 338 if (fromkey == NULL) { 339 /* We are matching the first hop */ 340 if (d->from.hostname != NULL || d->from.nkeys != 0) 341 continue; 342 } else if (match_key_hop("from", fromkey, &d->from) != 0) 343 continue; 344 345 /* Match 'to' key */ 346 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 347 continue; 348 349 /* Match user if specified */ 350 if (d->to.user != NULL && user != NULL && 351 !match_pattern(user, d->to.user)) 352 continue; 353 354 /* successfully matched this constraint */ 355 if (hostnamep != NULL) 356 *hostnamep = d->to.hostname; 357 debug2_f("allowed for hostname %s", 358 d->to.hostname == NULL ? "*" : d->to.hostname); 359 return 0; 360 } 361 /* no match */ 362 debug2_f("%s identity \"%s\" not permitted for this destination", 363 sshkey_type(id->key), id->comment); 364 return -1; 365 } 366 367 /* 368 * Check whether hostkeys on a SocketEntry and the optionally specified user 369 * are permitted by the destination constraints on the Identity. 370 * Returns 0 on success or -1 otherwise. 371 */ 372 static int 373 identity_permitted(Identity *id, SocketEntry *e, char *user, 374 const char **forward_hostnamep, const char **last_hostnamep) 375 { 376 size_t i; 377 const char **hp; 378 struct hostkey_sid *hks; 379 const struct sshkey *fromkey = NULL; 380 const char *test_user; 381 char *fp1, *fp2; 382 383 /* XXX remove logspam */ 384 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 385 "%zu constraints", sshkey_type(id->key), id->comment, 386 e->nsession_ids, id->ndest_constraints); 387 if (id->ndest_constraints == 0) 388 return 0; /* unconstrained */ 389 if (e->nsession_ids == 0) 390 return 0; /* local use */ 391 /* 392 * Walk through the hops recorded by session_id and try to find a 393 * constraint that satisfies each. 394 */ 395 for (i = 0; i < e->nsession_ids; i++) { 396 hks = e->session_ids + i; 397 if (hks->key == NULL) 398 fatal_f("internal error: no bound key"); 399 /* XXX remove logspam */ 400 fp1 = fp2 = NULL; 401 if (fromkey != NULL && 402 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 403 SSH_FP_DEFAULT)) == NULL) 404 fatal_f("fingerprint failed"); 405 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 406 SSH_FP_DEFAULT)) == NULL) 407 fatal_f("fingerprint failed"); 408 debug3_f("socketentry fd=%d, entry %zu %s, " 409 "from hostkey %s %s to user %s hostkey %s %s", 410 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 411 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 412 fromkey ? fp1 : "", user ? user : "(ANY)", 413 sshkey_type(hks->key), fp2); 414 free(fp1); 415 free(fp2); 416 /* 417 * Record the hostnames for the initial forwarding and 418 * the final destination. 419 */ 420 hp = NULL; 421 if (i == e->nsession_ids - 1) 422 hp = last_hostnamep; 423 else if (i == 0) 424 hp = forward_hostnamep; 425 /* Special handling for final recorded binding */ 426 test_user = NULL; 427 if (i == e->nsession_ids - 1) { 428 /* Can only check user at final hop */ 429 test_user = user; 430 /* 431 * user is only presented for signature requests. 432 * If this is the case, make sure last binding is not 433 * for a forwarding. 434 */ 435 if (hks->forwarded && user != NULL) { 436 error_f("tried to sign on forwarding hop"); 437 return -1; 438 } 439 } else if (!hks->forwarded) { 440 error_f("tried to forward though signing bind"); 441 return -1; 442 } 443 if (permitted_by_dest_constraints(fromkey, hks->key, id, 444 test_user, hp) != 0) 445 return -1; 446 fromkey = hks->key; 447 } 448 /* 449 * Another special case: if the last bound session ID was for a 450 * forwarding, and this function is not being called to check a sign 451 * request (i.e. no 'user' supplied), then only permit the key if 452 * there is a permission that would allow it to be used at another 453 * destination. This hides keys that are allowed to be used to 454 * authenticate *to* a host but not permitted for *use* beyond it. 455 */ 456 hks = &e->session_ids[e->nsession_ids - 1]; 457 if (hks->forwarded && user == NULL && 458 permitted_by_dest_constraints(hks->key, NULL, id, 459 NULL, NULL) != 0) { 460 debug3_f("key permitted at host but not after"); 461 return -1; 462 } 463 464 /* success */ 465 return 0; 466 } 467 468 /* return matching private key for given public key */ 469 static Identity * 470 lookup_identity(struct sshkey *key) 471 { 472 Identity *id; 473 474 TAILQ_FOREACH(id, &idtab->idlist, next) { 475 if (sshkey_equal(key, id->key)) 476 return (id); 477 } 478 return (NULL); 479 } 480 481 /* Check confirmation of keysign request */ 482 static int 483 confirm_key(Identity *id, const char *extra) 484 { 485 char *p; 486 int ret = -1; 487 488 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 489 if (p != NULL && 490 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 491 id->comment, p, 492 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 493 ret = 0; 494 free(p); 495 496 return (ret); 497 } 498 499 static void 500 send_status(SocketEntry *e, int success) 501 { 502 int r; 503 504 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 505 (r = sshbuf_put_u8(e->output, success ? 506 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 507 fatal_fr(r, "compose"); 508 } 509 510 /* send list of supported public keys to 'client' */ 511 static void 512 process_request_identities(SocketEntry *e) 513 { 514 Identity *id; 515 struct sshbuf *msg, *keys; 516 int r; 517 u_int nentries = 0; 518 519 debug2_f("entering"); 520 521 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 522 fatal_f("sshbuf_new failed"); 523 TAILQ_FOREACH(id, &idtab->idlist, next) { 524 /* identity not visible, don't include in response */ 525 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 526 continue; 527 if ((r = sshkey_puts_opts(id->key, keys, 528 SSHKEY_SERIALIZE_INFO)) != 0 || 529 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 530 error_fr(r, "compose key/comment"); 531 continue; 532 } 533 nentries++; 534 } 535 debug2_f("replying with %u allowed of %u available keys", 536 nentries, idtab->nentries); 537 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 538 (r = sshbuf_put_u32(msg, nentries)) != 0 || 539 (r = sshbuf_putb(msg, keys)) != 0) 540 fatal_fr(r, "compose"); 541 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 542 fatal_fr(r, "enqueue"); 543 sshbuf_free(msg); 544 sshbuf_free(keys); 545 } 546 547 548 static char * 549 agent_decode_alg(struct sshkey *key, u_int flags) 550 { 551 if (key->type == KEY_RSA) { 552 if (flags & SSH_AGENT_RSA_SHA2_256) 553 return "rsa-sha2-256"; 554 else if (flags & SSH_AGENT_RSA_SHA2_512) 555 return "rsa-sha2-512"; 556 } else if (key->type == KEY_RSA_CERT) { 557 if (flags & SSH_AGENT_RSA_SHA2_256) 558 return "rsa-sha2-256-cert-v01@openssh.com"; 559 else if (flags & SSH_AGENT_RSA_SHA2_512) 560 return "rsa-sha2-512-cert-v01@openssh.com"; 561 } 562 return NULL; 563 } 564 565 /* 566 * Attempt to parse the contents of a buffer as a SSH publickey userauth 567 * request, checking its contents for consistency and matching the embedded 568 * key against the one that is being used for signing. 569 * Note: does not modify msg buffer. 570 * Optionally extract the username, session ID and/or hostkey from the request. 571 */ 572 static int 573 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 574 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 575 { 576 struct sshbuf *b = NULL, *sess_id = NULL; 577 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 578 int r; 579 u_char t, sig_follows; 580 struct sshkey *mkey = NULL, *hostkey = NULL; 581 582 if (userp != NULL) 583 *userp = NULL; 584 if (sess_idp != NULL) 585 *sess_idp = NULL; 586 if (hostkeyp != NULL) 587 *hostkeyp = NULL; 588 if ((b = sshbuf_fromb(msg)) == NULL) 589 fatal_f("sshbuf_fromb"); 590 591 /* SSH userauth request */ 592 if ((r = sshbuf_froms(b, &sess_id)) != 0) 593 goto out; 594 if (sshbuf_len(sess_id) == 0) { 595 r = SSH_ERR_INVALID_FORMAT; 596 goto out; 597 } 598 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 599 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 600 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 601 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 602 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 603 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 604 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 605 goto out; 606 if (t != SSH2_MSG_USERAUTH_REQUEST || 607 sig_follows != 1 || 608 strcmp(service, "ssh-connection") != 0 || 609 !sshkey_equal(expected_key, mkey) || 610 sshkey_type_from_name(pkalg) != expected_key->type) { 611 r = SSH_ERR_INVALID_FORMAT; 612 goto out; 613 } 614 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 615 if ((r = sshkey_froms(b, &hostkey)) != 0) 616 goto out; 617 } else if (strcmp(method, "publickey") != 0) { 618 r = SSH_ERR_INVALID_FORMAT; 619 goto out; 620 } 621 if (sshbuf_len(b) != 0) { 622 r = SSH_ERR_INVALID_FORMAT; 623 goto out; 624 } 625 /* success */ 626 r = 0; 627 debug3_f("well formed userauth"); 628 if (userp != NULL) { 629 *userp = user; 630 user = NULL; 631 } 632 if (sess_idp != NULL) { 633 *sess_idp = sess_id; 634 sess_id = NULL; 635 } 636 if (hostkeyp != NULL) { 637 *hostkeyp = hostkey; 638 hostkey = NULL; 639 } 640 out: 641 sshbuf_free(b); 642 sshbuf_free(sess_id); 643 free(user); 644 free(service); 645 free(method); 646 free(pkalg); 647 sshkey_free(mkey); 648 sshkey_free(hostkey); 649 return r; 650 } 651 652 /* 653 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 654 * Note: does not modify buffer. 655 */ 656 static int 657 parse_sshsig_request(struct sshbuf *msg) 658 { 659 int r; 660 struct sshbuf *b; 661 662 if ((b = sshbuf_fromb(msg)) == NULL) 663 fatal_f("sshbuf_fromb"); 664 665 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 666 (r = sshbuf_consume(b, 6)) != 0 || 667 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 668 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 669 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 670 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 671 goto out; 672 if (sshbuf_len(b) != 0) { 673 r = SSH_ERR_INVALID_FORMAT; 674 goto out; 675 } 676 /* success */ 677 r = 0; 678 out: 679 sshbuf_free(b); 680 return r; 681 } 682 683 /* 684 * This function inspects a message to be signed by a FIDO key that has a 685 * web-like application string (i.e. one that does not begin with "ssh:". 686 * It checks that the message is one of those expected for SSH operations 687 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 688 * for the web. 689 */ 690 static int 691 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 692 { 693 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 694 debug_f("signed data matches public key userauth request"); 695 return 1; 696 } 697 if (parse_sshsig_request(data) == 0) { 698 debug_f("signed data matches SSHSIG signature request"); 699 return 1; 700 } 701 702 /* XXX check CA signature operation */ 703 704 error("web-origin key attempting to sign non-SSH message"); 705 return 0; 706 } 707 708 static int 709 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 710 { 711 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 712 return SSH_ERR_INVALID_ARGUMENT; 713 if (sshbuf_len(a) != sshbuf_len(b)) 714 return SSH_ERR_INVALID_FORMAT; 715 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 716 return SSH_ERR_INVALID_FORMAT; 717 return 0; 718 } 719 720 /* ssh2 only */ 721 static void 722 process_sign_request2(SocketEntry *e) 723 { 724 u_char *signature = NULL; 725 size_t slen = 0; 726 u_int compat = 0, flags; 727 int r, ok = -1, retried = 0; 728 char *fp = NULL, *pin = NULL, *prompt = NULL; 729 char *user = NULL, *sig_dest = NULL; 730 const char *fwd_host = NULL, *dest_host = NULL; 731 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 732 struct sshkey *key = NULL, *hostkey = NULL; 733 struct identity *id; 734 struct notifier_ctx *notifier = NULL; 735 736 debug_f("entering"); 737 738 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 739 fatal_f("sshbuf_new failed"); 740 if ((r = sshkey_froms(e->request, &key)) != 0 || 741 (r = sshbuf_get_stringb(e->request, data)) != 0 || 742 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 743 error_fr(r, "parse"); 744 goto send; 745 } 746 747 if ((id = lookup_identity(key)) == NULL) { 748 verbose_f("%s key not found", sshkey_type(key)); 749 goto send; 750 } 751 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 752 SSH_FP_DEFAULT)) == NULL) 753 fatal_f("fingerprint failed"); 754 755 if (id->ndest_constraints != 0) { 756 if (e->nsession_ids == 0) { 757 logit_f("refusing use of destination-constrained key " 758 "to sign on unbound connection"); 759 goto send; 760 } 761 if (parse_userauth_request(data, key, &user, &sid, 762 &hostkey) != 0) { 763 logit_f("refusing use of destination-constrained key " 764 "to sign an unidentified signature"); 765 goto send; 766 } 767 /* XXX logspam */ 768 debug_f("user=%s", user); 769 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 770 goto send; 771 /* XXX display fwd_host/dest_host in askpass UI */ 772 /* 773 * Ensure that the session ID is the most recent one 774 * registered on the socket - it should have been bound by 775 * ssh immediately before userauth. 776 */ 777 if (buf_equal(sid, 778 e->session_ids[e->nsession_ids - 1].sid) != 0) { 779 error_f("unexpected session ID (%zu listed) on " 780 "signature request for target user %s with " 781 "key %s %s", e->nsession_ids, user, 782 sshkey_type(id->key), fp); 783 goto send; 784 } 785 /* 786 * Ensure that the hostkey embedded in the signature matches 787 * the one most recently bound to the socket. An exception is 788 * made for the initial forwarding hop. 789 */ 790 if (e->nsession_ids > 1 && hostkey == NULL) { 791 error_f("refusing use of destination-constrained key: " 792 "no hostkey recorded in signature for forwarded " 793 "connection"); 794 goto send; 795 } 796 if (hostkey != NULL && !sshkey_equal(hostkey, 797 e->session_ids[e->nsession_ids - 1].key)) { 798 error_f("refusing use of destination-constrained key: " 799 "mismatch between hostkey in request and most " 800 "recently bound session"); 801 goto send; 802 } 803 xasprintf(&sig_dest, "public key authentication request for " 804 "user \"%s\" to listed host", user); 805 } 806 if (id->confirm && confirm_key(id, sig_dest) != 0) { 807 verbose_f("user refused key"); 808 goto send; 809 } 810 if (sshkey_is_sk(id->key)) { 811 if (restrict_websafe && 812 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 813 !check_websafe_message_contents(key, data)) { 814 /* error already logged */ 815 goto send; 816 } 817 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 818 notifier = notify_start(0, 819 "Confirm user presence for key %s %s%s%s", 820 sshkey_type(id->key), fp, 821 sig_dest == NULL ? "" : "\n", 822 sig_dest == NULL ? "" : sig_dest); 823 } 824 } 825 retry_pin: 826 if ((r = sshkey_sign(id->key, &signature, &slen, 827 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 828 id->sk_provider, pin, compat)) != 0) { 829 debug_fr(r, "sshkey_sign"); 830 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 831 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 832 notify_complete(notifier, NULL); 833 notifier = NULL; 834 /* XXX include sig_dest */ 835 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 836 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 837 " and confirm user presence " : " ", 838 sshkey_type(id->key), fp); 839 pin = read_passphrase(prompt, RP_USE_ASKPASS); 840 retried = 1; 841 goto retry_pin; 842 } 843 error_fr(r, "sshkey_sign"); 844 goto send; 845 } 846 /* Success */ 847 ok = 0; 848 send: 849 debug_f("good signature"); 850 notify_complete(notifier, "User presence confirmed"); 851 852 if (ok == 0) { 853 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 854 (r = sshbuf_put_string(msg, signature, slen)) != 0) 855 fatal_fr(r, "compose"); 856 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 857 fatal_fr(r, "compose failure"); 858 859 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 860 fatal_fr(r, "enqueue"); 861 862 sshbuf_free(sid); 863 sshbuf_free(data); 864 sshbuf_free(msg); 865 sshkey_free(key); 866 sshkey_free(hostkey); 867 free(fp); 868 free(signature); 869 free(sig_dest); 870 free(user); 871 free(prompt); 872 if (pin != NULL) 873 freezero(pin, strlen(pin)); 874 } 875 876 /* shared */ 877 static void 878 process_remove_identity(SocketEntry *e) 879 { 880 int r, success = 0; 881 struct sshkey *key = NULL; 882 Identity *id; 883 884 debug2_f("entering"); 885 if ((r = sshkey_froms(e->request, &key)) != 0) { 886 error_fr(r, "parse key"); 887 goto done; 888 } 889 if ((id = lookup_identity(key)) == NULL) { 890 debug_f("key not found"); 891 goto done; 892 } 893 /* identity not visible, cannot be removed */ 894 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 895 goto done; /* error already logged */ 896 /* We have this key, free it. */ 897 if (idtab->nentries < 1) 898 fatal_f("internal error: nentries %d", idtab->nentries); 899 TAILQ_REMOVE(&idtab->idlist, id, next); 900 free_identity(id); 901 idtab->nentries--; 902 success = 1; 903 done: 904 sshkey_free(key); 905 send_status(e, success); 906 } 907 908 static void 909 process_remove_all_identities(SocketEntry *e) 910 { 911 Identity *id; 912 913 debug2_f("entering"); 914 /* Loop over all identities and clear the keys. */ 915 for (id = TAILQ_FIRST(&idtab->idlist); id; 916 id = TAILQ_FIRST(&idtab->idlist)) { 917 TAILQ_REMOVE(&idtab->idlist, id, next); 918 free_identity(id); 919 } 920 921 /* Mark that there are no identities. */ 922 idtab->nentries = 0; 923 924 /* Send success. */ 925 send_status(e, 1); 926 } 927 928 /* removes expired keys and returns number of seconds until the next expiry */ 929 static time_t 930 reaper(void) 931 { 932 time_t deadline = 0, now = monotime(); 933 Identity *id, *nxt; 934 935 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 936 nxt = TAILQ_NEXT(id, next); 937 if (id->death == 0) 938 continue; 939 if (now >= id->death) { 940 debug("expiring key '%s'", id->comment); 941 TAILQ_REMOVE(&idtab->idlist, id, next); 942 free_identity(id); 943 idtab->nentries--; 944 } else 945 deadline = (deadline == 0) ? id->death : 946 MINIMUM(deadline, id->death); 947 } 948 if (deadline == 0 || deadline <= now) 949 return 0; 950 else 951 return (deadline - now); 952 } 953 954 static int 955 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 956 { 957 u_char key_is_ca; 958 size_t elen = 0; 959 int r; 960 struct sshkey *k = NULL; 961 char *fp; 962 963 memset(dch, '\0', sizeof(*dch)); 964 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 965 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 966 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 967 error_fr(r, "parse"); 968 goto out; 969 } 970 if (elen != 0) { 971 error_f("unsupported extensions (len %zu)", elen); 972 r = SSH_ERR_FEATURE_UNSUPPORTED; 973 goto out; 974 } 975 if (*dch->hostname == '\0') { 976 free(dch->hostname); 977 dch->hostname = NULL; 978 } 979 if (*dch->user == '\0') { 980 free(dch->user); 981 dch->user = NULL; 982 } 983 while (sshbuf_len(b) != 0) { 984 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 985 dch->nkeys + 1, sizeof(*dch->keys)); 986 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 987 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 988 if ((r = sshkey_froms(b, &k)) != 0 || 989 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 990 goto out; 991 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 992 SSH_FP_DEFAULT)) == NULL) 993 fatal_f("fingerprint failed"); 994 debug3_f("%s%s%s: adding %skey %s %s", 995 dch->user == NULL ? "" : dch->user, 996 dch->user == NULL ? "" : "@", 997 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 998 free(fp); 999 dch->keys[dch->nkeys] = k; 1000 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1001 dch->nkeys++; 1002 k = NULL; /* transferred */ 1003 } 1004 /* success */ 1005 r = 0; 1006 out: 1007 sshkey_free(k); 1008 return r; 1009 } 1010 1011 static int 1012 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1013 { 1014 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1015 int r; 1016 size_t elen = 0; 1017 1018 debug3_f("entering"); 1019 1020 memset(dc, '\0', sizeof(*dc)); 1021 if ((r = sshbuf_froms(m, &b)) != 0 || 1022 (r = sshbuf_froms(b, &frombuf)) != 0 || 1023 (r = sshbuf_froms(b, &tobuf)) != 0 || 1024 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1025 error_fr(r, "parse"); 1026 goto out; 1027 } 1028 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1029 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1030 goto out; /* already logged */ 1031 if (elen != 0) { 1032 error_f("unsupported extensions (len %zu)", elen); 1033 r = SSH_ERR_FEATURE_UNSUPPORTED; 1034 goto out; 1035 } 1036 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1037 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1038 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1039 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1040 /* check consistency */ 1041 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1042 dc->from.user != NULL) { 1043 error_f("inconsistent \"from\" specification"); 1044 r = SSH_ERR_INVALID_FORMAT; 1045 goto out; 1046 } 1047 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1048 error_f("incomplete \"to\" specification"); 1049 r = SSH_ERR_INVALID_FORMAT; 1050 goto out; 1051 } 1052 /* success */ 1053 r = 0; 1054 out: 1055 sshbuf_free(b); 1056 sshbuf_free(frombuf); 1057 sshbuf_free(tobuf); 1058 return r; 1059 } 1060 1061 static int 1062 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1063 struct dest_constraint **dcsp, size_t *ndcsp) 1064 { 1065 char *ext_name = NULL; 1066 int r; 1067 struct sshbuf *b = NULL; 1068 1069 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1070 error_fr(r, "parse constraint extension"); 1071 goto out; 1072 } 1073 debug_f("constraint ext %s", ext_name); 1074 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1075 if (sk_providerp == NULL) { 1076 error_f("%s not valid here", ext_name); 1077 r = SSH_ERR_INVALID_FORMAT; 1078 goto out; 1079 } 1080 if (*sk_providerp != NULL) { 1081 error_f("%s already set", ext_name); 1082 r = SSH_ERR_INVALID_FORMAT; 1083 goto out; 1084 } 1085 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1086 error_fr(r, "parse %s", ext_name); 1087 goto out; 1088 } 1089 } else if (strcmp(ext_name, 1090 "restrict-destination-v00@openssh.com") == 0) { 1091 if (*dcsp != NULL) { 1092 error_f("%s already set", ext_name); 1093 goto out; 1094 } 1095 if ((r = sshbuf_froms(m, &b)) != 0) { 1096 error_fr(r, "parse %s outer", ext_name); 1097 goto out; 1098 } 1099 while (sshbuf_len(b) != 0) { 1100 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1101 error_f("too many %s constraints", ext_name); 1102 goto out; 1103 } 1104 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1105 sizeof(**dcsp)); 1106 if ((r = parse_dest_constraint(b, 1107 *dcsp + (*ndcsp)++)) != 0) 1108 goto out; /* error already logged */ 1109 } 1110 } else { 1111 error_f("unsupported constraint \"%s\"", ext_name); 1112 r = SSH_ERR_FEATURE_UNSUPPORTED; 1113 goto out; 1114 } 1115 /* success */ 1116 r = 0; 1117 out: 1118 free(ext_name); 1119 sshbuf_free(b); 1120 return r; 1121 } 1122 1123 static int 1124 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1125 u_int *secondsp, int *confirmp, char **sk_providerp, 1126 struct dest_constraint **dcsp, size_t *ndcsp) 1127 { 1128 u_char ctype; 1129 int r; 1130 u_int seconds, maxsign = 0; 1131 1132 while (sshbuf_len(m)) { 1133 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1134 error_fr(r, "parse constraint type"); 1135 goto out; 1136 } 1137 switch (ctype) { 1138 case SSH_AGENT_CONSTRAIN_LIFETIME: 1139 if (*deathp != 0) { 1140 error_f("lifetime already set"); 1141 r = SSH_ERR_INVALID_FORMAT; 1142 goto out; 1143 } 1144 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1145 error_fr(r, "parse lifetime constraint"); 1146 goto out; 1147 } 1148 *deathp = monotime() + seconds; 1149 *secondsp = seconds; 1150 break; 1151 case SSH_AGENT_CONSTRAIN_CONFIRM: 1152 if (*confirmp != 0) { 1153 error_f("confirm already set"); 1154 r = SSH_ERR_INVALID_FORMAT; 1155 goto out; 1156 } 1157 *confirmp = 1; 1158 break; 1159 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1160 if (k == NULL) { 1161 error_f("maxsign not valid here"); 1162 r = SSH_ERR_INVALID_FORMAT; 1163 goto out; 1164 } 1165 if (maxsign != 0) { 1166 error_f("maxsign already set"); 1167 r = SSH_ERR_INVALID_FORMAT; 1168 goto out; 1169 } 1170 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1171 error_fr(r, "parse maxsign constraint"); 1172 goto out; 1173 } 1174 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1175 error_fr(r, "enable maxsign"); 1176 goto out; 1177 } 1178 break; 1179 case SSH_AGENT_CONSTRAIN_EXTENSION: 1180 if ((r = parse_key_constraint_extension(m, 1181 sk_providerp, dcsp, ndcsp)) != 0) 1182 goto out; /* error already logged */ 1183 break; 1184 default: 1185 error_f("Unknown constraint %d", ctype); 1186 r = SSH_ERR_FEATURE_UNSUPPORTED; 1187 goto out; 1188 } 1189 } 1190 /* success */ 1191 r = 0; 1192 out: 1193 return r; 1194 } 1195 1196 static void 1197 process_add_identity(SocketEntry *e) 1198 { 1199 Identity *id; 1200 int success = 0, confirm = 0; 1201 char *fp, *comment = NULL, *sk_provider = NULL; 1202 char canonical_provider[PATH_MAX]; 1203 time_t death = 0; 1204 u_int seconds = 0; 1205 struct dest_constraint *dest_constraints = NULL; 1206 size_t ndest_constraints = 0; 1207 struct sshkey *k = NULL; 1208 int r = SSH_ERR_INTERNAL_ERROR; 1209 1210 debug2_f("entering"); 1211 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1212 k == NULL || 1213 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1214 error_fr(r, "parse"); 1215 goto out; 1216 } 1217 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1218 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1219 error_f("failed to parse constraints"); 1220 sshbuf_reset(e->request); 1221 goto out; 1222 } 1223 1224 if (sk_provider != NULL) { 1225 if (!sshkey_is_sk(k)) { 1226 error("Cannot add provider: %s is not an " 1227 "authenticator-hosted key", sshkey_type(k)); 1228 goto out; 1229 } 1230 if (strcasecmp(sk_provider, "internal") == 0) { 1231 debug_f("internal provider"); 1232 } else { 1233 if (realpath(sk_provider, canonical_provider) == NULL) { 1234 verbose("failed provider \"%.100s\": " 1235 "realpath: %s", sk_provider, 1236 strerror(errno)); 1237 goto out; 1238 } 1239 free(sk_provider); 1240 sk_provider = xstrdup(canonical_provider); 1241 if (match_pattern_list(sk_provider, 1242 allowed_providers, 0) != 1) { 1243 error("Refusing add key: " 1244 "provider %s not allowed", sk_provider); 1245 goto out; 1246 } 1247 } 1248 } 1249 if ((r = sshkey_shield_private(k)) != 0) { 1250 error_fr(r, "shield private"); 1251 goto out; 1252 } 1253 if (lifetime && !death) 1254 death = monotime() + lifetime; 1255 if ((id = lookup_identity(k)) == NULL) { 1256 id = xcalloc(1, sizeof(Identity)); 1257 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1258 /* Increment the number of identities. */ 1259 idtab->nentries++; 1260 } else { 1261 /* identity not visible, do not update */ 1262 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1263 goto out; /* error already logged */ 1264 /* key state might have been updated */ 1265 sshkey_free(id->key); 1266 free(id->comment); 1267 free(id->sk_provider); 1268 free_dest_constraints(id->dest_constraints, 1269 id->ndest_constraints); 1270 } 1271 /* success */ 1272 id->key = k; 1273 id->comment = comment; 1274 id->death = death; 1275 id->confirm = confirm; 1276 id->sk_provider = sk_provider; 1277 id->dest_constraints = dest_constraints; 1278 id->ndest_constraints = ndest_constraints; 1279 1280 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1281 SSH_FP_DEFAULT)) == NULL) 1282 fatal_f("sshkey_fingerprint failed"); 1283 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1284 "(provider: %s) (destination constraints: %zu)", 1285 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1286 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1287 free(fp); 1288 /* transferred */ 1289 k = NULL; 1290 comment = NULL; 1291 sk_provider = NULL; 1292 dest_constraints = NULL; 1293 ndest_constraints = 0; 1294 success = 1; 1295 out: 1296 free(sk_provider); 1297 free(comment); 1298 sshkey_free(k); 1299 free_dest_constraints(dest_constraints, ndest_constraints); 1300 send_status(e, success); 1301 } 1302 1303 /* XXX todo: encrypt sensitive data with passphrase */ 1304 static void 1305 process_lock_agent(SocketEntry *e, int lock) 1306 { 1307 int r, success = 0, delay; 1308 char *passwd; 1309 u_char passwdhash[LOCK_SIZE]; 1310 static u_int fail_count = 0; 1311 size_t pwlen; 1312 1313 debug2_f("entering"); 1314 /* 1315 * This is deliberately fatal: the user has requested that we lock, 1316 * but we can't parse their request properly. The only safe thing to 1317 * do is abort. 1318 */ 1319 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1320 fatal_fr(r, "parse"); 1321 if (pwlen == 0) { 1322 debug("empty password not supported"); 1323 } else if (locked && !lock) { 1324 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1325 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1326 fatal("bcrypt_pbkdf"); 1327 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1328 debug("agent unlocked"); 1329 locked = 0; 1330 fail_count = 0; 1331 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1332 success = 1; 1333 } else { 1334 /* delay in 0.1s increments up to 10s */ 1335 if (fail_count < 100) 1336 fail_count++; 1337 delay = 100000 * fail_count; 1338 debug("unlock failed, delaying %0.1lf seconds", 1339 (double)delay/1000000); 1340 usleep(delay); 1341 } 1342 explicit_bzero(passwdhash, sizeof(passwdhash)); 1343 } else if (!locked && lock) { 1344 debug("agent locked"); 1345 locked = 1; 1346 arc4random_buf(lock_salt, sizeof(lock_salt)); 1347 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1348 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1349 fatal("bcrypt_pbkdf"); 1350 success = 1; 1351 } 1352 freezero(passwd, pwlen); 1353 send_status(e, success); 1354 } 1355 1356 static void 1357 no_identities(SocketEntry *e) 1358 { 1359 struct sshbuf *msg; 1360 int r; 1361 1362 if ((msg = sshbuf_new()) == NULL) 1363 fatal_f("sshbuf_new failed"); 1364 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1365 (r = sshbuf_put_u32(msg, 0)) != 0 || 1366 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1367 fatal_fr(r, "compose"); 1368 sshbuf_free(msg); 1369 } 1370 1371 #ifdef ENABLE_PKCS11 1372 static void 1373 process_add_smartcard_key(SocketEntry *e) 1374 { 1375 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1376 char **comments = NULL; 1377 int r, i, count = 0, success = 0, confirm = 0; 1378 u_int seconds = 0; 1379 time_t death = 0; 1380 struct sshkey **keys = NULL, *k; 1381 Identity *id; 1382 struct dest_constraint *dest_constraints = NULL; 1383 size_t ndest_constraints = 0; 1384 1385 debug2_f("entering"); 1386 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1387 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1388 error_fr(r, "parse"); 1389 goto send; 1390 } 1391 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1392 NULL, &dest_constraints, &ndest_constraints) != 0) { 1393 error_f("failed to parse constraints"); 1394 goto send; 1395 } 1396 if (realpath(provider, canonical_provider) == NULL) { 1397 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1398 provider, strerror(errno)); 1399 goto send; 1400 } 1401 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1402 verbose("refusing PKCS#11 add of \"%.100s\": " 1403 "provider not allowed", canonical_provider); 1404 goto send; 1405 } 1406 debug_f("add %.100s", canonical_provider); 1407 if (lifetime && !death) 1408 death = monotime() + lifetime; 1409 1410 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1411 for (i = 0; i < count; i++) { 1412 k = keys[i]; 1413 if (lookup_identity(k) == NULL) { 1414 id = xcalloc(1, sizeof(Identity)); 1415 id->key = k; 1416 keys[i] = NULL; /* transferred */ 1417 id->provider = xstrdup(canonical_provider); 1418 if (*comments[i] != '\0') { 1419 id->comment = comments[i]; 1420 comments[i] = NULL; /* transferred */ 1421 } else { 1422 id->comment = xstrdup(canonical_provider); 1423 } 1424 id->death = death; 1425 id->confirm = confirm; 1426 id->dest_constraints = dest_constraints; 1427 id->ndest_constraints = ndest_constraints; 1428 dest_constraints = NULL; /* transferred */ 1429 ndest_constraints = 0; 1430 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1431 idtab->nentries++; 1432 success = 1; 1433 } 1434 /* XXX update constraints for existing keys */ 1435 sshkey_free(keys[i]); 1436 free(comments[i]); 1437 } 1438 send: 1439 free(pin); 1440 free(provider); 1441 free(keys); 1442 free(comments); 1443 free_dest_constraints(dest_constraints, ndest_constraints); 1444 send_status(e, success); 1445 } 1446 1447 static void 1448 process_remove_smartcard_key(SocketEntry *e) 1449 { 1450 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1451 int r, success = 0; 1452 Identity *id, *nxt; 1453 1454 debug2_f("entering"); 1455 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1456 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1457 error_fr(r, "parse"); 1458 goto send; 1459 } 1460 free(pin); 1461 1462 if (realpath(provider, canonical_provider) == NULL) { 1463 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1464 provider, strerror(errno)); 1465 goto send; 1466 } 1467 1468 debug_f("remove %.100s", canonical_provider); 1469 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1470 nxt = TAILQ_NEXT(id, next); 1471 /* Skip file--based keys */ 1472 if (id->provider == NULL) 1473 continue; 1474 if (!strcmp(canonical_provider, id->provider)) { 1475 TAILQ_REMOVE(&idtab->idlist, id, next); 1476 free_identity(id); 1477 idtab->nentries--; 1478 } 1479 } 1480 if (pkcs11_del_provider(canonical_provider) == 0) 1481 success = 1; 1482 else 1483 error_f("pkcs11_del_provider failed"); 1484 send: 1485 free(provider); 1486 send_status(e, success); 1487 } 1488 #endif /* ENABLE_PKCS11 */ 1489 1490 static int 1491 process_ext_session_bind(SocketEntry *e) 1492 { 1493 int r, sid_match, key_match; 1494 struct sshkey *key = NULL; 1495 struct sshbuf *sid = NULL, *sig = NULL; 1496 char *fp = NULL; 1497 size_t i; 1498 u_char fwd = 0; 1499 1500 debug2_f("entering"); 1501 if ((r = sshkey_froms(e->request, &key)) != 0 || 1502 (r = sshbuf_froms(e->request, &sid)) != 0 || 1503 (r = sshbuf_froms(e->request, &sig)) != 0 || 1504 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1505 error_fr(r, "parse"); 1506 goto out; 1507 } 1508 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1509 SSH_FP_DEFAULT)) == NULL) 1510 fatal_f("fingerprint failed"); 1511 /* check signature with hostkey on session ID */ 1512 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1513 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1514 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1515 goto out; 1516 } 1517 /* check whether sid/key already recorded */ 1518 for (i = 0; i < e->nsession_ids; i++) { 1519 if (!e->session_ids[i].forwarded) { 1520 error_f("attempt to bind session ID to socket " 1521 "previously bound for authentication attempt"); 1522 r = -1; 1523 goto out; 1524 } 1525 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1526 key_match = sshkey_equal(key, e->session_ids[i].key); 1527 if (sid_match && key_match) { 1528 debug_f("session ID already recorded for %s %s", 1529 sshkey_type(key), fp); 1530 r = 0; 1531 goto out; 1532 } else if (sid_match) { 1533 error_f("session ID recorded against different key " 1534 "for %s %s", sshkey_type(key), fp); 1535 r = -1; 1536 goto out; 1537 } 1538 /* 1539 * new sid with previously-seen key can happen, e.g. multiple 1540 * connections to the same host. 1541 */ 1542 } 1543 /* record new key/sid */ 1544 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1545 error_f("too many session IDs recorded"); 1546 goto out; 1547 } 1548 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1549 e->nsession_ids + 1, sizeof(*e->session_ids)); 1550 i = e->nsession_ids++; 1551 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1552 AGENT_MAX_SESSION_IDS); 1553 e->session_ids[i].key = key; 1554 e->session_ids[i].forwarded = fwd != 0; 1555 key = NULL; /* transferred */ 1556 /* can't transfer sid; it's refcounted and scoped to request's life */ 1557 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1558 fatal_f("sshbuf_new"); 1559 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1560 fatal_fr(r, "sshbuf_putb session ID"); 1561 /* success */ 1562 r = 0; 1563 out: 1564 free(fp); 1565 sshkey_free(key); 1566 sshbuf_free(sid); 1567 sshbuf_free(sig); 1568 return r == 0 ? 1 : 0; 1569 } 1570 1571 static void 1572 process_extension(SocketEntry *e) 1573 { 1574 int r, success = 0; 1575 char *name; 1576 1577 debug2_f("entering"); 1578 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1579 error_fr(r, "parse"); 1580 goto send; 1581 } 1582 if (strcmp(name, "session-bind@openssh.com") == 0) 1583 success = process_ext_session_bind(e); 1584 else 1585 debug_f("unsupported extension \"%s\"", name); 1586 free(name); 1587 send: 1588 send_status(e, success); 1589 } 1590 /* 1591 * dispatch incoming message. 1592 * returns 1 on success, 0 for incomplete messages or -1 on error. 1593 */ 1594 static int 1595 process_message(u_int socknum) 1596 { 1597 u_int msg_len; 1598 u_char type; 1599 const u_char *cp; 1600 int r; 1601 SocketEntry *e; 1602 1603 if (socknum >= sockets_alloc) 1604 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1605 e = &sockets[socknum]; 1606 1607 if (sshbuf_len(e->input) < 5) 1608 return 0; /* Incomplete message header. */ 1609 cp = sshbuf_ptr(e->input); 1610 msg_len = PEEK_U32(cp); 1611 if (msg_len > AGENT_MAX_LEN) { 1612 debug_f("socket %u (fd=%d) message too long %u > %u", 1613 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1614 return -1; 1615 } 1616 if (sshbuf_len(e->input) < msg_len + 4) 1617 return 0; /* Incomplete message body. */ 1618 1619 /* move the current input to e->request */ 1620 sshbuf_reset(e->request); 1621 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1622 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1623 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1624 r == SSH_ERR_STRING_TOO_LARGE) { 1625 error_fr(r, "parse"); 1626 return -1; 1627 } 1628 fatal_fr(r, "parse"); 1629 } 1630 1631 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1632 1633 /* check whether agent is locked */ 1634 if (locked && type != SSH_AGENTC_UNLOCK) { 1635 sshbuf_reset(e->request); 1636 switch (type) { 1637 case SSH2_AGENTC_REQUEST_IDENTITIES: 1638 /* send empty lists */ 1639 no_identities(e); 1640 break; 1641 default: 1642 /* send a fail message for all other request types */ 1643 send_status(e, 0); 1644 } 1645 return 1; 1646 } 1647 1648 switch (type) { 1649 case SSH_AGENTC_LOCK: 1650 case SSH_AGENTC_UNLOCK: 1651 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1652 break; 1653 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1654 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1655 break; 1656 /* ssh2 */ 1657 case SSH2_AGENTC_SIGN_REQUEST: 1658 process_sign_request2(e); 1659 break; 1660 case SSH2_AGENTC_REQUEST_IDENTITIES: 1661 process_request_identities(e); 1662 break; 1663 case SSH2_AGENTC_ADD_IDENTITY: 1664 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1665 process_add_identity(e); 1666 break; 1667 case SSH2_AGENTC_REMOVE_IDENTITY: 1668 process_remove_identity(e); 1669 break; 1670 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1671 process_remove_all_identities(e); 1672 break; 1673 #ifdef ENABLE_PKCS11 1674 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1675 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1676 process_add_smartcard_key(e); 1677 break; 1678 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1679 process_remove_smartcard_key(e); 1680 break; 1681 #endif /* ENABLE_PKCS11 */ 1682 case SSH_AGENTC_EXTENSION: 1683 process_extension(e); 1684 break; 1685 default: 1686 /* Unknown message. Respond with failure. */ 1687 error("Unknown message %d", type); 1688 sshbuf_reset(e->request); 1689 send_status(e, 0); 1690 break; 1691 } 1692 return 1; 1693 } 1694 1695 static void 1696 new_socket(sock_type type, int fd) 1697 { 1698 u_int i, old_alloc, new_alloc; 1699 1700 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1701 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1702 set_nonblock(fd); 1703 1704 if (fd > max_fd) 1705 max_fd = fd; 1706 1707 for (i = 0; i < sockets_alloc; i++) 1708 if (sockets[i].type == AUTH_UNUSED) { 1709 sockets[i].fd = fd; 1710 if ((sockets[i].input = sshbuf_new()) == NULL || 1711 (sockets[i].output = sshbuf_new()) == NULL || 1712 (sockets[i].request = sshbuf_new()) == NULL) 1713 fatal_f("sshbuf_new failed"); 1714 sockets[i].type = type; 1715 return; 1716 } 1717 old_alloc = sockets_alloc; 1718 new_alloc = sockets_alloc + 10; 1719 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1720 sizeof(sockets[0])); 1721 for (i = old_alloc; i < new_alloc; i++) 1722 sockets[i].type = AUTH_UNUSED; 1723 sockets_alloc = new_alloc; 1724 sockets[old_alloc].fd = fd; 1725 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1726 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1727 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1728 fatal_f("sshbuf_new failed"); 1729 sockets[old_alloc].type = type; 1730 } 1731 1732 static int 1733 handle_socket_read(u_int socknum) 1734 { 1735 struct sockaddr_un sunaddr; 1736 socklen_t slen; 1737 uid_t euid; 1738 gid_t egid; 1739 int fd; 1740 1741 slen = sizeof(sunaddr); 1742 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1743 if (fd == -1) { 1744 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1745 return -1; 1746 } 1747 if (getpeereid(fd, &euid, &egid) == -1) { 1748 error("getpeereid %d failed: %s", fd, strerror(errno)); 1749 close(fd); 1750 return -1; 1751 } 1752 if ((euid != 0) && (getuid() != euid)) { 1753 error("uid mismatch: peer euid %u != uid %u", 1754 (u_int) euid, (u_int) getuid()); 1755 close(fd); 1756 return -1; 1757 } 1758 new_socket(AUTH_CONNECTION, fd); 1759 return 0; 1760 } 1761 1762 static int 1763 handle_conn_read(u_int socknum) 1764 { 1765 char buf[AGENT_RBUF_LEN]; 1766 ssize_t len; 1767 int r; 1768 1769 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1770 if (len == -1) { 1771 if (errno == EAGAIN || errno == EINTR) 1772 return 0; 1773 error_f("read error on socket %u (fd %d): %s", 1774 socknum, sockets[socknum].fd, strerror(errno)); 1775 } 1776 return -1; 1777 } 1778 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1779 fatal_fr(r, "compose"); 1780 explicit_bzero(buf, sizeof(buf)); 1781 for (;;) { 1782 if ((r = process_message(socknum)) == -1) 1783 return -1; 1784 else if (r == 0) 1785 break; 1786 } 1787 return 0; 1788 } 1789 1790 static int 1791 handle_conn_write(u_int socknum) 1792 { 1793 ssize_t len; 1794 int r; 1795 1796 if (sshbuf_len(sockets[socknum].output) == 0) 1797 return 0; /* shouldn't happen */ 1798 if ((len = write(sockets[socknum].fd, 1799 sshbuf_ptr(sockets[socknum].output), 1800 sshbuf_len(sockets[socknum].output))) <= 0) { 1801 if (len == -1) { 1802 if (errno == EAGAIN || errno == EINTR) 1803 return 0; 1804 error_f("read error on socket %u (fd %d): %s", 1805 socknum, sockets[socknum].fd, strerror(errno)); 1806 } 1807 return -1; 1808 } 1809 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1810 fatal_fr(r, "consume"); 1811 return 0; 1812 } 1813 1814 static void 1815 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1816 { 1817 size_t i; 1818 u_int socknum, activefds = npfd; 1819 1820 for (i = 0; i < npfd; i++) { 1821 if (pfd[i].revents == 0) 1822 continue; 1823 /* Find sockets entry */ 1824 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1825 if (sockets[socknum].type != AUTH_SOCKET && 1826 sockets[socknum].type != AUTH_CONNECTION) 1827 continue; 1828 if (pfd[i].fd == sockets[socknum].fd) 1829 break; 1830 } 1831 if (socknum >= sockets_alloc) { 1832 error_f("no socket for fd %d", pfd[i].fd); 1833 continue; 1834 } 1835 /* Process events */ 1836 switch (sockets[socknum].type) { 1837 case AUTH_SOCKET: 1838 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1839 break; 1840 if (npfd > maxfds) { 1841 debug3("out of fds (active %u >= limit %u); " 1842 "skipping accept", activefds, maxfds); 1843 break; 1844 } 1845 if (handle_socket_read(socknum) == 0) 1846 activefds++; 1847 break; 1848 case AUTH_CONNECTION: 1849 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1850 handle_conn_read(socknum) != 0) 1851 goto close_sock; 1852 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1853 handle_conn_write(socknum) != 0) { 1854 close_sock: 1855 if (activefds == 0) 1856 fatal("activefds == 0 at close_sock"); 1857 close_socket(&sockets[socknum]); 1858 activefds--; 1859 break; 1860 } 1861 break; 1862 default: 1863 break; 1864 } 1865 } 1866 } 1867 1868 static int 1869 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1870 { 1871 struct pollfd *pfd = *pfdp; 1872 size_t i, j, npfd = 0; 1873 time_t deadline; 1874 int r; 1875 1876 /* Count active sockets */ 1877 for (i = 0; i < sockets_alloc; i++) { 1878 switch (sockets[i].type) { 1879 case AUTH_SOCKET: 1880 case AUTH_CONNECTION: 1881 npfd++; 1882 break; 1883 case AUTH_UNUSED: 1884 break; 1885 default: 1886 fatal("Unknown socket type %d", sockets[i].type); 1887 break; 1888 } 1889 } 1890 if (npfd != *npfdp && 1891 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1892 fatal_f("recallocarray failed"); 1893 *pfdp = pfd; 1894 *npfdp = npfd; 1895 1896 for (i = j = 0; i < sockets_alloc; i++) { 1897 switch (sockets[i].type) { 1898 case AUTH_SOCKET: 1899 if (npfd > maxfds) { 1900 debug3("out of fds (active %zu >= limit %u); " 1901 "skipping arming listener", npfd, maxfds); 1902 break; 1903 } 1904 pfd[j].fd = sockets[i].fd; 1905 pfd[j].revents = 0; 1906 pfd[j].events = POLLIN; 1907 j++; 1908 break; 1909 case AUTH_CONNECTION: 1910 pfd[j].fd = sockets[i].fd; 1911 pfd[j].revents = 0; 1912 /* 1913 * Only prepare to read if we can handle a full-size 1914 * input read buffer and enqueue a max size reply.. 1915 */ 1916 if ((r = sshbuf_check_reserve(sockets[i].input, 1917 AGENT_RBUF_LEN)) == 0 && 1918 (r = sshbuf_check_reserve(sockets[i].output, 1919 AGENT_MAX_LEN)) == 0) 1920 pfd[j].events = POLLIN; 1921 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1922 fatal_fr(r, "reserve"); 1923 if (sshbuf_len(sockets[i].output) > 0) 1924 pfd[j].events |= POLLOUT; 1925 j++; 1926 break; 1927 default: 1928 break; 1929 } 1930 } 1931 deadline = reaper(); 1932 if (parent_alive_interval != 0) 1933 deadline = (deadline == 0) ? parent_alive_interval : 1934 MINIMUM(deadline, parent_alive_interval); 1935 if (deadline == 0) { 1936 *timeoutp = -1; /* INFTIM */ 1937 } else { 1938 if (deadline > INT_MAX / 1000) 1939 *timeoutp = INT_MAX / 1000; 1940 else 1941 *timeoutp = deadline * 1000; 1942 } 1943 return (1); 1944 } 1945 1946 static void 1947 cleanup_socket(void) 1948 { 1949 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1950 return; 1951 debug_f("cleanup"); 1952 if (socket_name[0]) 1953 unlink(socket_name); 1954 if (socket_dir[0]) 1955 rmdir(socket_dir); 1956 } 1957 1958 void 1959 cleanup_exit(int i) 1960 { 1961 cleanup_socket(); 1962 _exit(i); 1963 } 1964 1965 /*ARGSUSED*/ 1966 static void 1967 cleanup_handler(int sig) 1968 { 1969 cleanup_socket(); 1970 #ifdef ENABLE_PKCS11 1971 pkcs11_terminate(); 1972 #endif 1973 _exit(2); 1974 } 1975 1976 static void 1977 check_parent_exists(void) 1978 { 1979 /* 1980 * If our parent has exited then getppid() will return (pid_t)1, 1981 * so testing for that should be safe. 1982 */ 1983 if (parent_pid != -1 && getppid() != parent_pid) { 1984 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1985 cleanup_socket(); 1986 _exit(2); 1987 } 1988 } 1989 1990 static void 1991 usage(void) 1992 { 1993 fprintf(stderr, 1994 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1995 " [-P allowed_providers] [-t life]\n" 1996 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1997 " [-t life] command [arg ...]\n" 1998 " ssh-agent [-c | -s] -k\n"); 1999 exit(1); 2000 } 2001 2002 int 2003 main(int ac, char **av) 2004 { 2005 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2006 int sock, ch, result, saved_errno; 2007 char *shell, *format, *pidstr, *agentsocket = NULL; 2008 #ifdef HAVE_SETRLIMIT 2009 struct rlimit rlim; 2010 #endif 2011 extern int optind; 2012 extern char *optarg; 2013 pid_t pid; 2014 char pidstrbuf[1 + 3 * sizeof pid]; 2015 size_t len; 2016 mode_t prev_mask; 2017 int timeout = -1; /* INFTIM */ 2018 struct pollfd *pfd = NULL; 2019 size_t npfd = 0; 2020 u_int maxfds; 2021 2022 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2023 sanitise_stdfd(); 2024 2025 /* drop */ 2026 setegid(getgid()); 2027 setgid(getgid()); 2028 2029 platform_disable_tracing(0); /* strict=no */ 2030 2031 #ifdef RLIMIT_NOFILE 2032 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2033 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2034 #endif 2035 2036 __progname = ssh_get_progname(av[0]); 2037 seed_rng(); 2038 2039 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2040 switch (ch) { 2041 case 'E': 2042 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2043 if (fingerprint_hash == -1) 2044 fatal("Invalid hash algorithm \"%s\"", optarg); 2045 break; 2046 case 'c': 2047 if (s_flag) 2048 usage(); 2049 c_flag++; 2050 break; 2051 case 'k': 2052 k_flag++; 2053 break; 2054 case 'O': 2055 if (strcmp(optarg, "no-restrict-websafe") == 0) 2056 restrict_websafe = 0; 2057 else 2058 fatal("Unknown -O option"); 2059 break; 2060 case 'P': 2061 if (allowed_providers != NULL) 2062 fatal("-P option already specified"); 2063 allowed_providers = xstrdup(optarg); 2064 break; 2065 case 's': 2066 if (c_flag) 2067 usage(); 2068 s_flag++; 2069 break; 2070 case 'd': 2071 if (d_flag || D_flag) 2072 usage(); 2073 d_flag++; 2074 break; 2075 case 'D': 2076 if (d_flag || D_flag) 2077 usage(); 2078 D_flag++; 2079 break; 2080 case 'a': 2081 agentsocket = optarg; 2082 break; 2083 case 't': 2084 if ((lifetime = convtime(optarg)) == -1) { 2085 fprintf(stderr, "Invalid lifetime\n"); 2086 usage(); 2087 } 2088 break; 2089 default: 2090 usage(); 2091 } 2092 } 2093 ac -= optind; 2094 av += optind; 2095 2096 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2097 usage(); 2098 2099 if (allowed_providers == NULL) 2100 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2101 2102 if (ac == 0 && !c_flag && !s_flag) { 2103 shell = getenv("SHELL"); 2104 if (shell != NULL && (len = strlen(shell)) > 2 && 2105 strncmp(shell + len - 3, "csh", 3) == 0) 2106 c_flag = 1; 2107 } 2108 if (k_flag) { 2109 const char *errstr = NULL; 2110 2111 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2112 if (pidstr == NULL) { 2113 fprintf(stderr, "%s not set, cannot kill agent\n", 2114 SSH_AGENTPID_ENV_NAME); 2115 exit(1); 2116 } 2117 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2118 if (errstr) { 2119 fprintf(stderr, 2120 "%s=\"%s\", which is not a good PID: %s\n", 2121 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2122 exit(1); 2123 } 2124 if (kill(pid, SIGTERM) == -1) { 2125 perror("kill"); 2126 exit(1); 2127 } 2128 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2129 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2130 printf(format, SSH_AGENTPID_ENV_NAME); 2131 printf("echo Agent pid %ld killed;\n", (long)pid); 2132 exit(0); 2133 } 2134 2135 /* 2136 * Minimum file descriptors: 2137 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2138 * a few spare for libc / stack protectors / sanitisers, etc. 2139 */ 2140 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2141 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2142 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2143 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2144 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2145 2146 parent_pid = getpid(); 2147 2148 if (agentsocket == NULL) { 2149 /* Create private directory for agent socket */ 2150 mktemp_proto(socket_dir, sizeof(socket_dir)); 2151 if (mkdtemp(socket_dir) == NULL) { 2152 perror("mkdtemp: private socket dir"); 2153 exit(1); 2154 } 2155 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2156 (long)parent_pid); 2157 } else { 2158 /* Try to use specified agent socket */ 2159 socket_dir[0] = '\0'; 2160 strlcpy(socket_name, agentsocket, sizeof socket_name); 2161 } 2162 2163 /* 2164 * Create socket early so it will exist before command gets run from 2165 * the parent. 2166 */ 2167 prev_mask = umask(0177); 2168 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2169 if (sock < 0) { 2170 /* XXX - unix_listener() calls error() not perror() */ 2171 *socket_name = '\0'; /* Don't unlink any existing file */ 2172 cleanup_exit(1); 2173 } 2174 umask(prev_mask); 2175 2176 /* 2177 * Fork, and have the parent execute the command, if any, or present 2178 * the socket data. The child continues as the authentication agent. 2179 */ 2180 if (D_flag || d_flag) { 2181 log_init(__progname, 2182 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2183 SYSLOG_FACILITY_AUTH, 1); 2184 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2185 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2186 SSH_AUTHSOCKET_ENV_NAME); 2187 printf("echo Agent pid %ld;\n", (long)parent_pid); 2188 fflush(stdout); 2189 goto skip; 2190 } 2191 pid = fork(); 2192 if (pid == -1) { 2193 perror("fork"); 2194 cleanup_exit(1); 2195 } 2196 if (pid != 0) { /* Parent - execute the given command. */ 2197 close(sock); 2198 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2199 if (ac == 0) { 2200 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2201 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2202 SSH_AUTHSOCKET_ENV_NAME); 2203 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2204 SSH_AGENTPID_ENV_NAME); 2205 printf("echo Agent pid %ld;\n", (long)pid); 2206 exit(0); 2207 } 2208 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2209 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2210 perror("setenv"); 2211 exit(1); 2212 } 2213 execvp(av[0], av); 2214 perror(av[0]); 2215 exit(1); 2216 } 2217 /* child */ 2218 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2219 2220 if (setsid() == -1) { 2221 error("setsid: %s", strerror(errno)); 2222 cleanup_exit(1); 2223 } 2224 2225 (void)chdir("/"); 2226 if (stdfd_devnull(1, 1, 1) == -1) 2227 error_f("stdfd_devnull failed"); 2228 2229 #ifdef HAVE_SETRLIMIT 2230 /* deny core dumps, since memory contains unencrypted private keys */ 2231 rlim.rlim_cur = rlim.rlim_max = 0; 2232 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2233 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2234 cleanup_exit(1); 2235 } 2236 #endif 2237 2238 skip: 2239 2240 cleanup_pid = getpid(); 2241 2242 #ifdef ENABLE_PKCS11 2243 pkcs11_init(0); 2244 #endif 2245 new_socket(AUTH_SOCKET, sock); 2246 if (ac > 0) 2247 parent_alive_interval = 10; 2248 idtab_init(); 2249 ssh_signal(SIGPIPE, SIG_IGN); 2250 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2251 ssh_signal(SIGHUP, cleanup_handler); 2252 ssh_signal(SIGTERM, cleanup_handler); 2253 2254 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2255 fatal("%s: pledge: %s", __progname, strerror(errno)); 2256 platform_pledge_agent(); 2257 2258 while (1) { 2259 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2260 result = poll(pfd, npfd, timeout); 2261 saved_errno = errno; 2262 if (parent_alive_interval != 0) 2263 check_parent_exists(); 2264 (void) reaper(); /* remove expired keys */ 2265 if (result == -1) { 2266 if (saved_errno == EINTR) 2267 continue; 2268 fatal("poll: %s", strerror(saved_errno)); 2269 } else if (result > 0) 2270 after_poll(pfd, npfd, maxfds); 2271 } 2272 /* NOTREACHED */ 2273 } 2274