1 /* $OpenBSD: ssh-agent.c,v 1.297 2023/03/09 21:06:24 jcs 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 "log.h" 84 #include "misc.h" 85 #include "digest.h" 86 #include "ssherr.h" 87 #include "match.h" 88 #include "msg.h" 89 #include "pathnames.h" 90 #include "ssh-pkcs11.h" 91 #include "sk-api.h" 92 #include "myproposal.h" 93 94 #ifndef DEFAULT_ALLOWED_PROVIDERS 95 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 96 #endif 97 98 /* Maximum accepted message length */ 99 #define AGENT_MAX_LEN (256*1024) 100 /* Maximum bytes to read from client socket */ 101 #define AGENT_RBUF_LEN (4096) 102 /* Maximum number of recorded session IDs/hostkeys per connection */ 103 #define AGENT_MAX_SESSION_IDS 16 104 /* Maximum size of session ID */ 105 #define AGENT_MAX_SID_LEN 128 106 /* Maximum number of destination constraints to accept on a key */ 107 #define AGENT_MAX_DEST_CONSTRAINTS 1024 108 109 /* XXX store hostkey_sid in a refcounted tree */ 110 111 typedef enum { 112 AUTH_UNUSED = 0, 113 AUTH_SOCKET = 1, 114 AUTH_CONNECTION = 2, 115 } sock_type; 116 117 struct hostkey_sid { 118 struct sshkey *key; 119 struct sshbuf *sid; 120 int forwarded; 121 }; 122 123 typedef struct socket_entry { 124 int fd; 125 sock_type type; 126 struct sshbuf *input; 127 struct sshbuf *output; 128 struct sshbuf *request; 129 size_t nsession_ids; 130 struct hostkey_sid *session_ids; 131 } SocketEntry; 132 133 u_int sockets_alloc = 0; 134 SocketEntry *sockets = NULL; 135 136 typedef struct identity { 137 TAILQ_ENTRY(identity) next; 138 struct sshkey *key; 139 char *comment; 140 char *provider; 141 time_t death; 142 u_int confirm; 143 char *sk_provider; 144 struct dest_constraint *dest_constraints; 145 size_t ndest_constraints; 146 } Identity; 147 148 struct idtable { 149 int nentries; 150 TAILQ_HEAD(idqueue, identity) idlist; 151 }; 152 153 /* private key table */ 154 struct idtable *idtab; 155 156 int max_fd = 0; 157 158 /* pid of shell == parent of agent */ 159 pid_t parent_pid = -1; 160 time_t parent_alive_interval = 0; 161 162 /* pid of process for which cleanup_socket is applicable */ 163 pid_t cleanup_pid = 0; 164 165 /* pathname and directory for AUTH_SOCKET */ 166 char socket_name[PATH_MAX]; 167 char socket_dir[PATH_MAX]; 168 169 /* Pattern-list of allowed PKCS#11/Security key paths */ 170 static char *allowed_providers; 171 172 /* locking */ 173 #define LOCK_SIZE 32 174 #define LOCK_SALT_SIZE 16 175 #define LOCK_ROUNDS 1 176 int locked = 0; 177 u_char lock_pwhash[LOCK_SIZE]; 178 u_char lock_salt[LOCK_SALT_SIZE]; 179 180 extern char *__progname; 181 182 /* Default lifetime in seconds (0 == forever) */ 183 static int lifetime = 0; 184 185 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 186 187 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 188 static int restrict_websafe = 1; 189 190 /* 191 * Client connection count; incremented in new_socket() and decremented in 192 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 193 * normally initialized to 1, it will never reach 0. However, if the -x 194 * option is specified, it is initialized to 0 in main(); in that case, 195 * ssh-agent will exit as soon as it has had at least one client but no 196 * longer has any. 197 */ 198 static int xcount = 1; 199 200 static void 201 close_socket(SocketEntry *e) 202 { 203 size_t i; 204 int last = 0; 205 206 if (e->type == AUTH_CONNECTION) { 207 debug("xcount %d -> %d", xcount, xcount - 1); 208 if (--xcount == 0) 209 last = 1; 210 } 211 close(e->fd); 212 sshbuf_free(e->input); 213 sshbuf_free(e->output); 214 sshbuf_free(e->request); 215 for (i = 0; i < e->nsession_ids; i++) { 216 sshkey_free(e->session_ids[i].key); 217 sshbuf_free(e->session_ids[i].sid); 218 } 219 free(e->session_ids); 220 memset(e, '\0', sizeof(*e)); 221 e->fd = -1; 222 e->type = AUTH_UNUSED; 223 if (last) 224 cleanup_exit(0); 225 } 226 227 static void 228 idtab_init(void) 229 { 230 idtab = xcalloc(1, sizeof(*idtab)); 231 TAILQ_INIT(&idtab->idlist); 232 idtab->nentries = 0; 233 } 234 235 static void 236 free_dest_constraint_hop(struct dest_constraint_hop *dch) 237 { 238 u_int i; 239 240 if (dch == NULL) 241 return; 242 free(dch->user); 243 free(dch->hostname); 244 for (i = 0; i < dch->nkeys; i++) 245 sshkey_free(dch->keys[i]); 246 free(dch->keys); 247 free(dch->key_is_ca); 248 } 249 250 static void 251 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 252 { 253 size_t i; 254 255 for (i = 0; i < ndcs; i++) { 256 free_dest_constraint_hop(&dcs[i].from); 257 free_dest_constraint_hop(&dcs[i].to); 258 } 259 free(dcs); 260 } 261 262 static void 263 free_identity(Identity *id) 264 { 265 sshkey_free(id->key); 266 free(id->provider); 267 free(id->comment); 268 free(id->sk_provider); 269 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 270 free(id); 271 } 272 273 /* 274 * Match 'key' against the key/CA list in a destination constraint hop 275 * Returns 0 on success or -1 otherwise. 276 */ 277 static int 278 match_key_hop(const char *tag, const struct sshkey *key, 279 const struct dest_constraint_hop *dch) 280 { 281 const char *reason = NULL; 282 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 283 u_int i; 284 char *fp; 285 286 if (key == NULL) 287 return -1; 288 /* XXX logspam */ 289 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 290 SSH_FP_DEFAULT)) == NULL) 291 fatal_f("fingerprint failed"); 292 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 293 tag, hostname, sshkey_type(key), fp, dch->nkeys); 294 free(fp); 295 for (i = 0; i < dch->nkeys; i++) { 296 if (dch->keys[i] == NULL) 297 return -1; 298 /* XXX logspam */ 299 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 300 SSH_FP_DEFAULT)) == NULL) 301 fatal_f("fingerprint failed"); 302 debug3_f("%s: key %u: %s%s %s", tag, i, 303 dch->key_is_ca[i] ? "CA " : "", 304 sshkey_type(dch->keys[i]), fp); 305 free(fp); 306 if (!sshkey_is_cert(key)) { 307 /* plain key */ 308 if (dch->key_is_ca[i] || 309 !sshkey_equal(key, dch->keys[i])) 310 continue; 311 return 0; 312 } 313 /* certificate */ 314 if (!dch->key_is_ca[i]) 315 continue; 316 if (key->cert == NULL || key->cert->signature_key == NULL) 317 return -1; /* shouldn't happen */ 318 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 319 continue; 320 if (sshkey_cert_check_host(key, hostname, 1, 321 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 322 debug_f("cert %s / hostname %s rejected: %s", 323 key->cert->key_id, hostname, reason); 324 continue; 325 } 326 return 0; 327 } 328 return -1; 329 } 330 331 /* Check destination constraints on an identity against the hostkey/user */ 332 static int 333 permitted_by_dest_constraints(const struct sshkey *fromkey, 334 const struct sshkey *tokey, Identity *id, const char *user, 335 const char **hostnamep) 336 { 337 size_t i; 338 struct dest_constraint *d; 339 340 if (hostnamep != NULL) 341 *hostnamep = NULL; 342 for (i = 0; i < id->ndest_constraints; i++) { 343 d = id->dest_constraints + i; 344 /* XXX remove logspam */ 345 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 346 i, d->from.user ? d->from.user : "", 347 d->from.user ? "@" : "", 348 d->from.hostname ? d->from.hostname : "(ORIGIN)", 349 d->from.nkeys, 350 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 351 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 352 353 /* Match 'from' key */ 354 if (fromkey == NULL) { 355 /* We are matching the first hop */ 356 if (d->from.hostname != NULL || d->from.nkeys != 0) 357 continue; 358 } else if (match_key_hop("from", fromkey, &d->from) != 0) 359 continue; 360 361 /* Match 'to' key */ 362 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 363 continue; 364 365 /* Match user if specified */ 366 if (d->to.user != NULL && user != NULL && 367 !match_pattern(user, d->to.user)) 368 continue; 369 370 /* successfully matched this constraint */ 371 if (hostnamep != NULL) 372 *hostnamep = d->to.hostname; 373 debug2_f("allowed for hostname %s", 374 d->to.hostname == NULL ? "*" : d->to.hostname); 375 return 0; 376 } 377 /* no match */ 378 debug2_f("%s identity \"%s\" not permitted for this destination", 379 sshkey_type(id->key), id->comment); 380 return -1; 381 } 382 383 /* 384 * Check whether hostkeys on a SocketEntry and the optionally specified user 385 * are permitted by the destination constraints on the Identity. 386 * Returns 0 on success or -1 otherwise. 387 */ 388 static int 389 identity_permitted(Identity *id, SocketEntry *e, char *user, 390 const char **forward_hostnamep, const char **last_hostnamep) 391 { 392 size_t i; 393 const char **hp; 394 struct hostkey_sid *hks; 395 const struct sshkey *fromkey = NULL; 396 const char *test_user; 397 char *fp1, *fp2; 398 399 /* XXX remove logspam */ 400 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 401 "%zu constraints", sshkey_type(id->key), id->comment, 402 e->nsession_ids, id->ndest_constraints); 403 if (id->ndest_constraints == 0) 404 return 0; /* unconstrained */ 405 if (e->nsession_ids == 0) 406 return 0; /* local use */ 407 /* 408 * Walk through the hops recorded by session_id and try to find a 409 * constraint that satisfies each. 410 */ 411 for (i = 0; i < e->nsession_ids; i++) { 412 hks = e->session_ids + i; 413 if (hks->key == NULL) 414 fatal_f("internal error: no bound key"); 415 /* XXX remove logspam */ 416 fp1 = fp2 = NULL; 417 if (fromkey != NULL && 418 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 419 SSH_FP_DEFAULT)) == NULL) 420 fatal_f("fingerprint failed"); 421 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 422 SSH_FP_DEFAULT)) == NULL) 423 fatal_f("fingerprint failed"); 424 debug3_f("socketentry fd=%d, entry %zu %s, " 425 "from hostkey %s %s to user %s hostkey %s %s", 426 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 427 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 428 fromkey ? fp1 : "", user ? user : "(ANY)", 429 sshkey_type(hks->key), fp2); 430 free(fp1); 431 free(fp2); 432 /* 433 * Record the hostnames for the initial forwarding and 434 * the final destination. 435 */ 436 hp = NULL; 437 if (i == e->nsession_ids - 1) 438 hp = last_hostnamep; 439 else if (i == 0) 440 hp = forward_hostnamep; 441 /* Special handling for final recorded binding */ 442 test_user = NULL; 443 if (i == e->nsession_ids - 1) { 444 /* Can only check user at final hop */ 445 test_user = user; 446 /* 447 * user is only presented for signature requests. 448 * If this is the case, make sure last binding is not 449 * for a forwarding. 450 */ 451 if (hks->forwarded && user != NULL) { 452 error_f("tried to sign on forwarding hop"); 453 return -1; 454 } 455 } else if (!hks->forwarded) { 456 error_f("tried to forward though signing bind"); 457 return -1; 458 } 459 if (permitted_by_dest_constraints(fromkey, hks->key, id, 460 test_user, hp) != 0) 461 return -1; 462 fromkey = hks->key; 463 } 464 /* 465 * Another special case: if the last bound session ID was for a 466 * forwarding, and this function is not being called to check a sign 467 * request (i.e. no 'user' supplied), then only permit the key if 468 * there is a permission that would allow it to be used at another 469 * destination. This hides keys that are allowed to be used to 470 * authenticate *to* a host but not permitted for *use* beyond it. 471 */ 472 hks = &e->session_ids[e->nsession_ids - 1]; 473 if (hks->forwarded && user == NULL && 474 permitted_by_dest_constraints(hks->key, NULL, id, 475 NULL, NULL) != 0) { 476 debug3_f("key permitted at host but not after"); 477 return -1; 478 } 479 480 /* success */ 481 return 0; 482 } 483 484 /* return matching private key for given public key */ 485 static Identity * 486 lookup_identity(struct sshkey *key) 487 { 488 Identity *id; 489 490 TAILQ_FOREACH(id, &idtab->idlist, next) { 491 if (sshkey_equal(key, id->key)) 492 return (id); 493 } 494 return (NULL); 495 } 496 497 /* Check confirmation of keysign request */ 498 static int 499 confirm_key(Identity *id, const char *extra) 500 { 501 char *p; 502 int ret = -1; 503 504 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 505 if (p != NULL && 506 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 507 id->comment, p, 508 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 509 ret = 0; 510 free(p); 511 512 return (ret); 513 } 514 515 static void 516 send_status(SocketEntry *e, int success) 517 { 518 int r; 519 520 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 521 (r = sshbuf_put_u8(e->output, success ? 522 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 523 fatal_fr(r, "compose"); 524 } 525 526 /* send list of supported public keys to 'client' */ 527 static void 528 process_request_identities(SocketEntry *e) 529 { 530 Identity *id; 531 struct sshbuf *msg, *keys; 532 int r; 533 u_int nentries = 0; 534 535 debug2_f("entering"); 536 537 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 538 fatal_f("sshbuf_new failed"); 539 TAILQ_FOREACH(id, &idtab->idlist, next) { 540 /* identity not visible, don't include in response */ 541 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 542 continue; 543 if ((r = sshkey_puts_opts(id->key, keys, 544 SSHKEY_SERIALIZE_INFO)) != 0 || 545 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 546 error_fr(r, "compose key/comment"); 547 continue; 548 } 549 nentries++; 550 } 551 debug2_f("replying with %u allowed of %u available keys", 552 nentries, idtab->nentries); 553 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 554 (r = sshbuf_put_u32(msg, nentries)) != 0 || 555 (r = sshbuf_putb(msg, keys)) != 0) 556 fatal_fr(r, "compose"); 557 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 558 fatal_fr(r, "enqueue"); 559 sshbuf_free(msg); 560 sshbuf_free(keys); 561 } 562 563 564 static char * 565 agent_decode_alg(struct sshkey *key, u_int flags) 566 { 567 if (key->type == KEY_RSA) { 568 if (flags & SSH_AGENT_RSA_SHA2_256) 569 return "rsa-sha2-256"; 570 else if (flags & SSH_AGENT_RSA_SHA2_512) 571 return "rsa-sha2-512"; 572 } else if (key->type == KEY_RSA_CERT) { 573 if (flags & SSH_AGENT_RSA_SHA2_256) 574 return "rsa-sha2-256-cert-v01@openssh.com"; 575 else if (flags & SSH_AGENT_RSA_SHA2_512) 576 return "rsa-sha2-512-cert-v01@openssh.com"; 577 } 578 return NULL; 579 } 580 581 /* 582 * Attempt to parse the contents of a buffer as a SSH publickey userauth 583 * request, checking its contents for consistency and matching the embedded 584 * key against the one that is being used for signing. 585 * Note: does not modify msg buffer. 586 * Optionally extract the username, session ID and/or hostkey from the request. 587 */ 588 static int 589 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 590 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 591 { 592 struct sshbuf *b = NULL, *sess_id = NULL; 593 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 594 int r; 595 u_char t, sig_follows; 596 struct sshkey *mkey = NULL, *hostkey = NULL; 597 598 if (userp != NULL) 599 *userp = NULL; 600 if (sess_idp != NULL) 601 *sess_idp = NULL; 602 if (hostkeyp != NULL) 603 *hostkeyp = NULL; 604 if ((b = sshbuf_fromb(msg)) == NULL) 605 fatal_f("sshbuf_fromb"); 606 607 /* SSH userauth request */ 608 if ((r = sshbuf_froms(b, &sess_id)) != 0) 609 goto out; 610 if (sshbuf_len(sess_id) == 0) { 611 r = SSH_ERR_INVALID_FORMAT; 612 goto out; 613 } 614 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 615 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 616 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 617 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 618 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 619 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 620 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 621 goto out; 622 if (t != SSH2_MSG_USERAUTH_REQUEST || 623 sig_follows != 1 || 624 strcmp(service, "ssh-connection") != 0 || 625 !sshkey_equal(expected_key, mkey) || 626 sshkey_type_from_name(pkalg) != expected_key->type) { 627 r = SSH_ERR_INVALID_FORMAT; 628 goto out; 629 } 630 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 631 if ((r = sshkey_froms(b, &hostkey)) != 0) 632 goto out; 633 } else if (strcmp(method, "publickey") != 0) { 634 r = SSH_ERR_INVALID_FORMAT; 635 goto out; 636 } 637 if (sshbuf_len(b) != 0) { 638 r = SSH_ERR_INVALID_FORMAT; 639 goto out; 640 } 641 /* success */ 642 r = 0; 643 debug3_f("well formed userauth"); 644 if (userp != NULL) { 645 *userp = user; 646 user = NULL; 647 } 648 if (sess_idp != NULL) { 649 *sess_idp = sess_id; 650 sess_id = NULL; 651 } 652 if (hostkeyp != NULL) { 653 *hostkeyp = hostkey; 654 hostkey = NULL; 655 } 656 out: 657 sshbuf_free(b); 658 sshbuf_free(sess_id); 659 free(user); 660 free(service); 661 free(method); 662 free(pkalg); 663 sshkey_free(mkey); 664 sshkey_free(hostkey); 665 return r; 666 } 667 668 /* 669 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 670 * Note: does not modify buffer. 671 */ 672 static int 673 parse_sshsig_request(struct sshbuf *msg) 674 { 675 int r; 676 struct sshbuf *b; 677 678 if ((b = sshbuf_fromb(msg)) == NULL) 679 fatal_f("sshbuf_fromb"); 680 681 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 682 (r = sshbuf_consume(b, 6)) != 0 || 683 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 684 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 685 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 686 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 687 goto out; 688 if (sshbuf_len(b) != 0) { 689 r = SSH_ERR_INVALID_FORMAT; 690 goto out; 691 } 692 /* success */ 693 r = 0; 694 out: 695 sshbuf_free(b); 696 return r; 697 } 698 699 /* 700 * This function inspects a message to be signed by a FIDO key that has a 701 * web-like application string (i.e. one that does not begin with "ssh:". 702 * It checks that the message is one of those expected for SSH operations 703 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 704 * for the web. 705 */ 706 static int 707 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 708 { 709 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 710 debug_f("signed data matches public key userauth request"); 711 return 1; 712 } 713 if (parse_sshsig_request(data) == 0) { 714 debug_f("signed data matches SSHSIG signature request"); 715 return 1; 716 } 717 718 /* XXX check CA signature operation */ 719 720 error("web-origin key attempting to sign non-SSH message"); 721 return 0; 722 } 723 724 static int 725 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 726 { 727 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 728 return SSH_ERR_INVALID_ARGUMENT; 729 if (sshbuf_len(a) != sshbuf_len(b)) 730 return SSH_ERR_INVALID_FORMAT; 731 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 732 return SSH_ERR_INVALID_FORMAT; 733 return 0; 734 } 735 736 /* ssh2 only */ 737 static void 738 process_sign_request2(SocketEntry *e) 739 { 740 u_char *signature = NULL; 741 size_t slen = 0; 742 u_int compat = 0, flags; 743 int r, ok = -1, retried = 0; 744 char *fp = NULL, *pin = NULL, *prompt = NULL; 745 char *user = NULL, *sig_dest = NULL; 746 const char *fwd_host = NULL, *dest_host = NULL; 747 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 748 struct sshkey *key = NULL, *hostkey = NULL; 749 struct identity *id; 750 struct notifier_ctx *notifier = NULL; 751 752 debug_f("entering"); 753 754 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 755 fatal_f("sshbuf_new failed"); 756 if ((r = sshkey_froms(e->request, &key)) != 0 || 757 (r = sshbuf_get_stringb(e->request, data)) != 0 || 758 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 759 error_fr(r, "parse"); 760 goto send; 761 } 762 763 if ((id = lookup_identity(key)) == NULL) { 764 verbose_f("%s key not found", sshkey_type(key)); 765 goto send; 766 } 767 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 768 SSH_FP_DEFAULT)) == NULL) 769 fatal_f("fingerprint failed"); 770 771 if (id->ndest_constraints != 0) { 772 if (e->nsession_ids == 0) { 773 logit_f("refusing use of destination-constrained key " 774 "to sign on unbound connection"); 775 goto send; 776 } 777 if (parse_userauth_request(data, key, &user, &sid, 778 &hostkey) != 0) { 779 logit_f("refusing use of destination-constrained key " 780 "to sign an unidentified signature"); 781 goto send; 782 } 783 /* XXX logspam */ 784 debug_f("user=%s", user); 785 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 786 goto send; 787 /* XXX display fwd_host/dest_host in askpass UI */ 788 /* 789 * Ensure that the session ID is the most recent one 790 * registered on the socket - it should have been bound by 791 * ssh immediately before userauth. 792 */ 793 if (buf_equal(sid, 794 e->session_ids[e->nsession_ids - 1].sid) != 0) { 795 error_f("unexpected session ID (%zu listed) on " 796 "signature request for target user %s with " 797 "key %s %s", e->nsession_ids, user, 798 sshkey_type(id->key), fp); 799 goto send; 800 } 801 /* 802 * Ensure that the hostkey embedded in the signature matches 803 * the one most recently bound to the socket. An exception is 804 * made for the initial forwarding hop. 805 */ 806 if (e->nsession_ids > 1 && hostkey == NULL) { 807 error_f("refusing use of destination-constrained key: " 808 "no hostkey recorded in signature for forwarded " 809 "connection"); 810 goto send; 811 } 812 if (hostkey != NULL && !sshkey_equal(hostkey, 813 e->session_ids[e->nsession_ids - 1].key)) { 814 error_f("refusing use of destination-constrained key: " 815 "mismatch between hostkey in request and most " 816 "recently bound session"); 817 goto send; 818 } 819 xasprintf(&sig_dest, "public key authentication request for " 820 "user \"%s\" to listed host", user); 821 } 822 if (id->confirm && confirm_key(id, sig_dest) != 0) { 823 verbose_f("user refused key"); 824 goto send; 825 } 826 if (sshkey_is_sk(id->key)) { 827 if (restrict_websafe && 828 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 829 !check_websafe_message_contents(key, data)) { 830 /* error already logged */ 831 goto send; 832 } 833 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 834 notifier = notify_start(0, 835 "Confirm user presence for key %s %s%s%s", 836 sshkey_type(id->key), fp, 837 sig_dest == NULL ? "" : "\n", 838 sig_dest == NULL ? "" : sig_dest); 839 } 840 } 841 retry_pin: 842 if ((r = sshkey_sign(id->key, &signature, &slen, 843 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 844 id->sk_provider, pin, compat)) != 0) { 845 debug_fr(r, "sshkey_sign"); 846 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 847 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 848 notify_complete(notifier, NULL); 849 notifier = NULL; 850 /* XXX include sig_dest */ 851 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 852 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 853 " and confirm user presence " : " ", 854 sshkey_type(id->key), fp); 855 pin = read_passphrase(prompt, RP_USE_ASKPASS); 856 retried = 1; 857 goto retry_pin; 858 } 859 error_fr(r, "sshkey_sign"); 860 goto send; 861 } 862 /* Success */ 863 ok = 0; 864 send: 865 debug_f("good signature"); 866 notify_complete(notifier, "User presence confirmed"); 867 868 if (ok == 0) { 869 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 870 (r = sshbuf_put_string(msg, signature, slen)) != 0) 871 fatal_fr(r, "compose"); 872 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 873 fatal_fr(r, "compose failure"); 874 875 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 876 fatal_fr(r, "enqueue"); 877 878 sshbuf_free(sid); 879 sshbuf_free(data); 880 sshbuf_free(msg); 881 sshkey_free(key); 882 sshkey_free(hostkey); 883 free(fp); 884 free(signature); 885 free(sig_dest); 886 free(user); 887 free(prompt); 888 if (pin != NULL) 889 freezero(pin, strlen(pin)); 890 } 891 892 /* shared */ 893 static void 894 process_remove_identity(SocketEntry *e) 895 { 896 int r, success = 0; 897 struct sshkey *key = NULL; 898 Identity *id; 899 900 debug2_f("entering"); 901 if ((r = sshkey_froms(e->request, &key)) != 0) { 902 error_fr(r, "parse key"); 903 goto done; 904 } 905 if ((id = lookup_identity(key)) == NULL) { 906 debug_f("key not found"); 907 goto done; 908 } 909 /* identity not visible, cannot be removed */ 910 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 911 goto done; /* error already logged */ 912 /* We have this key, free it. */ 913 if (idtab->nentries < 1) 914 fatal_f("internal error: nentries %d", idtab->nentries); 915 TAILQ_REMOVE(&idtab->idlist, id, next); 916 free_identity(id); 917 idtab->nentries--; 918 success = 1; 919 done: 920 sshkey_free(key); 921 send_status(e, success); 922 } 923 924 static void 925 process_remove_all_identities(SocketEntry *e) 926 { 927 Identity *id; 928 929 debug2_f("entering"); 930 /* Loop over all identities and clear the keys. */ 931 for (id = TAILQ_FIRST(&idtab->idlist); id; 932 id = TAILQ_FIRST(&idtab->idlist)) { 933 TAILQ_REMOVE(&idtab->idlist, id, next); 934 free_identity(id); 935 } 936 937 /* Mark that there are no identities. */ 938 idtab->nentries = 0; 939 940 /* Send success. */ 941 send_status(e, 1); 942 } 943 944 /* removes expired keys and returns number of seconds until the next expiry */ 945 static time_t 946 reaper(void) 947 { 948 time_t deadline = 0, now = monotime(); 949 Identity *id, *nxt; 950 951 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 952 nxt = TAILQ_NEXT(id, next); 953 if (id->death == 0) 954 continue; 955 if (now >= id->death) { 956 debug("expiring key '%s'", id->comment); 957 TAILQ_REMOVE(&idtab->idlist, id, next); 958 free_identity(id); 959 idtab->nentries--; 960 } else 961 deadline = (deadline == 0) ? id->death : 962 MINIMUM(deadline, id->death); 963 } 964 if (deadline == 0 || deadline <= now) 965 return 0; 966 else 967 return (deadline - now); 968 } 969 970 static int 971 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 972 { 973 u_char key_is_ca; 974 size_t elen = 0; 975 int r; 976 struct sshkey *k = NULL; 977 char *fp; 978 979 memset(dch, '\0', sizeof(*dch)); 980 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 981 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 982 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 983 error_fr(r, "parse"); 984 goto out; 985 } 986 if (elen != 0) { 987 error_f("unsupported extensions (len %zu)", elen); 988 r = SSH_ERR_FEATURE_UNSUPPORTED; 989 goto out; 990 } 991 if (*dch->hostname == '\0') { 992 free(dch->hostname); 993 dch->hostname = NULL; 994 } 995 if (*dch->user == '\0') { 996 free(dch->user); 997 dch->user = NULL; 998 } 999 while (sshbuf_len(b) != 0) { 1000 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1001 dch->nkeys + 1, sizeof(*dch->keys)); 1002 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1003 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1004 if ((r = sshkey_froms(b, &k)) != 0 || 1005 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1006 goto out; 1007 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1008 SSH_FP_DEFAULT)) == NULL) 1009 fatal_f("fingerprint failed"); 1010 debug3_f("%s%s%s: adding %skey %s %s", 1011 dch->user == NULL ? "" : dch->user, 1012 dch->user == NULL ? "" : "@", 1013 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1014 free(fp); 1015 dch->keys[dch->nkeys] = k; 1016 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1017 dch->nkeys++; 1018 k = NULL; /* transferred */ 1019 } 1020 /* success */ 1021 r = 0; 1022 out: 1023 sshkey_free(k); 1024 return r; 1025 } 1026 1027 static int 1028 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1029 { 1030 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1031 int r; 1032 size_t elen = 0; 1033 1034 debug3_f("entering"); 1035 1036 memset(dc, '\0', sizeof(*dc)); 1037 if ((r = sshbuf_froms(m, &b)) != 0 || 1038 (r = sshbuf_froms(b, &frombuf)) != 0 || 1039 (r = sshbuf_froms(b, &tobuf)) != 0 || 1040 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1041 error_fr(r, "parse"); 1042 goto out; 1043 } 1044 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1045 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1046 goto out; /* already logged */ 1047 if (elen != 0) { 1048 error_f("unsupported extensions (len %zu)", elen); 1049 r = SSH_ERR_FEATURE_UNSUPPORTED; 1050 goto out; 1051 } 1052 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1053 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1054 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1055 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1056 /* check consistency */ 1057 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1058 dc->from.user != NULL) { 1059 error_f("inconsistent \"from\" specification"); 1060 r = SSH_ERR_INVALID_FORMAT; 1061 goto out; 1062 } 1063 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1064 error_f("incomplete \"to\" specification"); 1065 r = SSH_ERR_INVALID_FORMAT; 1066 goto out; 1067 } 1068 /* success */ 1069 r = 0; 1070 out: 1071 sshbuf_free(b); 1072 sshbuf_free(frombuf); 1073 sshbuf_free(tobuf); 1074 return r; 1075 } 1076 1077 static int 1078 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1079 struct dest_constraint **dcsp, size_t *ndcsp) 1080 { 1081 char *ext_name = NULL; 1082 int r; 1083 struct sshbuf *b = NULL; 1084 1085 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1086 error_fr(r, "parse constraint extension"); 1087 goto out; 1088 } 1089 debug_f("constraint ext %s", ext_name); 1090 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1091 if (sk_providerp == NULL) { 1092 error_f("%s not valid here", ext_name); 1093 r = SSH_ERR_INVALID_FORMAT; 1094 goto out; 1095 } 1096 if (*sk_providerp != NULL) { 1097 error_f("%s already set", ext_name); 1098 r = SSH_ERR_INVALID_FORMAT; 1099 goto out; 1100 } 1101 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1102 error_fr(r, "parse %s", ext_name); 1103 goto out; 1104 } 1105 } else if (strcmp(ext_name, 1106 "restrict-destination-v00@openssh.com") == 0) { 1107 if (*dcsp != NULL) { 1108 error_f("%s already set", ext_name); 1109 goto out; 1110 } 1111 if ((r = sshbuf_froms(m, &b)) != 0) { 1112 error_fr(r, "parse %s outer", ext_name); 1113 goto out; 1114 } 1115 while (sshbuf_len(b) != 0) { 1116 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1117 error_f("too many %s constraints", ext_name); 1118 goto out; 1119 } 1120 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1121 sizeof(**dcsp)); 1122 if ((r = parse_dest_constraint(b, 1123 *dcsp + (*ndcsp)++)) != 0) 1124 goto out; /* error already logged */ 1125 } 1126 } else { 1127 error_f("unsupported constraint \"%s\"", ext_name); 1128 r = SSH_ERR_FEATURE_UNSUPPORTED; 1129 goto out; 1130 } 1131 /* success */ 1132 r = 0; 1133 out: 1134 free(ext_name); 1135 sshbuf_free(b); 1136 return r; 1137 } 1138 1139 static int 1140 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1141 u_int *secondsp, int *confirmp, char **sk_providerp, 1142 struct dest_constraint **dcsp, size_t *ndcsp) 1143 { 1144 u_char ctype; 1145 int r; 1146 u_int seconds, maxsign = 0; 1147 1148 while (sshbuf_len(m)) { 1149 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1150 error_fr(r, "parse constraint type"); 1151 goto out; 1152 } 1153 switch (ctype) { 1154 case SSH_AGENT_CONSTRAIN_LIFETIME: 1155 if (*deathp != 0) { 1156 error_f("lifetime already set"); 1157 r = SSH_ERR_INVALID_FORMAT; 1158 goto out; 1159 } 1160 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1161 error_fr(r, "parse lifetime constraint"); 1162 goto out; 1163 } 1164 *deathp = monotime() + seconds; 1165 *secondsp = seconds; 1166 break; 1167 case SSH_AGENT_CONSTRAIN_CONFIRM: 1168 if (*confirmp != 0) { 1169 error_f("confirm already set"); 1170 r = SSH_ERR_INVALID_FORMAT; 1171 goto out; 1172 } 1173 *confirmp = 1; 1174 break; 1175 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1176 if (k == NULL) { 1177 error_f("maxsign not valid here"); 1178 r = SSH_ERR_INVALID_FORMAT; 1179 goto out; 1180 } 1181 if (maxsign != 0) { 1182 error_f("maxsign already set"); 1183 r = SSH_ERR_INVALID_FORMAT; 1184 goto out; 1185 } 1186 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1187 error_fr(r, "parse maxsign constraint"); 1188 goto out; 1189 } 1190 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1191 error_fr(r, "enable maxsign"); 1192 goto out; 1193 } 1194 break; 1195 case SSH_AGENT_CONSTRAIN_EXTENSION: 1196 if ((r = parse_key_constraint_extension(m, 1197 sk_providerp, dcsp, ndcsp)) != 0) 1198 goto out; /* error already logged */ 1199 break; 1200 default: 1201 error_f("Unknown constraint %d", ctype); 1202 r = SSH_ERR_FEATURE_UNSUPPORTED; 1203 goto out; 1204 } 1205 } 1206 /* success */ 1207 r = 0; 1208 out: 1209 return r; 1210 } 1211 1212 static void 1213 process_add_identity(SocketEntry *e) 1214 { 1215 Identity *id; 1216 int success = 0, confirm = 0; 1217 char *fp, *comment = NULL, *sk_provider = NULL; 1218 char canonical_provider[PATH_MAX]; 1219 time_t death = 0; 1220 u_int seconds = 0; 1221 struct dest_constraint *dest_constraints = NULL; 1222 size_t ndest_constraints = 0; 1223 struct sshkey *k = NULL; 1224 int r = SSH_ERR_INTERNAL_ERROR; 1225 1226 debug2_f("entering"); 1227 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1228 k == NULL || 1229 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1230 error_fr(r, "parse"); 1231 goto out; 1232 } 1233 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1234 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1235 error_f("failed to parse constraints"); 1236 sshbuf_reset(e->request); 1237 goto out; 1238 } 1239 1240 if (sk_provider != NULL) { 1241 if (!sshkey_is_sk(k)) { 1242 error("Cannot add provider: %s is not an " 1243 "authenticator-hosted key", sshkey_type(k)); 1244 goto out; 1245 } 1246 if (strcasecmp(sk_provider, "internal") == 0) { 1247 debug_f("internal provider"); 1248 } else { 1249 if (realpath(sk_provider, canonical_provider) == NULL) { 1250 verbose("failed provider \"%.100s\": " 1251 "realpath: %s", sk_provider, 1252 strerror(errno)); 1253 goto out; 1254 } 1255 free(sk_provider); 1256 sk_provider = xstrdup(canonical_provider); 1257 if (match_pattern_list(sk_provider, 1258 allowed_providers, 0) != 1) { 1259 error("Refusing add key: " 1260 "provider %s not allowed", sk_provider); 1261 goto out; 1262 } 1263 } 1264 } 1265 if ((r = sshkey_shield_private(k)) != 0) { 1266 error_fr(r, "shield private"); 1267 goto out; 1268 } 1269 if (lifetime && !death) 1270 death = monotime() + lifetime; 1271 if ((id = lookup_identity(k)) == NULL) { 1272 id = xcalloc(1, sizeof(Identity)); 1273 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1274 /* Increment the number of identities. */ 1275 idtab->nentries++; 1276 } else { 1277 /* identity not visible, do not update */ 1278 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1279 goto out; /* error already logged */ 1280 /* key state might have been updated */ 1281 sshkey_free(id->key); 1282 free(id->comment); 1283 free(id->sk_provider); 1284 free_dest_constraints(id->dest_constraints, 1285 id->ndest_constraints); 1286 } 1287 /* success */ 1288 id->key = k; 1289 id->comment = comment; 1290 id->death = death; 1291 id->confirm = confirm; 1292 id->sk_provider = sk_provider; 1293 id->dest_constraints = dest_constraints; 1294 id->ndest_constraints = ndest_constraints; 1295 1296 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1297 SSH_FP_DEFAULT)) == NULL) 1298 fatal_f("sshkey_fingerprint failed"); 1299 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1300 "(provider: %s) (destination constraints: %zu)", 1301 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1302 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1303 free(fp); 1304 /* transferred */ 1305 k = NULL; 1306 comment = NULL; 1307 sk_provider = NULL; 1308 dest_constraints = NULL; 1309 ndest_constraints = 0; 1310 success = 1; 1311 out: 1312 free(sk_provider); 1313 free(comment); 1314 sshkey_free(k); 1315 free_dest_constraints(dest_constraints, ndest_constraints); 1316 send_status(e, success); 1317 } 1318 1319 /* XXX todo: encrypt sensitive data with passphrase */ 1320 static void 1321 process_lock_agent(SocketEntry *e, int lock) 1322 { 1323 int r, success = 0, delay; 1324 char *passwd; 1325 u_char passwdhash[LOCK_SIZE]; 1326 static u_int fail_count = 0; 1327 size_t pwlen; 1328 1329 debug2_f("entering"); 1330 /* 1331 * This is deliberately fatal: the user has requested that we lock, 1332 * but we can't parse their request properly. The only safe thing to 1333 * do is abort. 1334 */ 1335 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1336 fatal_fr(r, "parse"); 1337 if (pwlen == 0) { 1338 debug("empty password not supported"); 1339 } else if (locked && !lock) { 1340 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1341 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1342 fatal("bcrypt_pbkdf"); 1343 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1344 debug("agent unlocked"); 1345 locked = 0; 1346 fail_count = 0; 1347 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1348 success = 1; 1349 } else { 1350 /* delay in 0.1s increments up to 10s */ 1351 if (fail_count < 100) 1352 fail_count++; 1353 delay = 100000 * fail_count; 1354 debug("unlock failed, delaying %0.1lf seconds", 1355 (double)delay/1000000); 1356 usleep(delay); 1357 } 1358 explicit_bzero(passwdhash, sizeof(passwdhash)); 1359 } else if (!locked && lock) { 1360 debug("agent locked"); 1361 locked = 1; 1362 arc4random_buf(lock_salt, sizeof(lock_salt)); 1363 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1364 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1365 fatal("bcrypt_pbkdf"); 1366 success = 1; 1367 } 1368 freezero(passwd, pwlen); 1369 send_status(e, success); 1370 } 1371 1372 static void 1373 no_identities(SocketEntry *e) 1374 { 1375 struct sshbuf *msg; 1376 int r; 1377 1378 if ((msg = sshbuf_new()) == NULL) 1379 fatal_f("sshbuf_new failed"); 1380 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1381 (r = sshbuf_put_u32(msg, 0)) != 0 || 1382 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1383 fatal_fr(r, "compose"); 1384 sshbuf_free(msg); 1385 } 1386 1387 #ifdef ENABLE_PKCS11 1388 static void 1389 process_add_smartcard_key(SocketEntry *e) 1390 { 1391 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1392 char **comments = NULL; 1393 int r, i, count = 0, success = 0, confirm = 0; 1394 u_int seconds = 0; 1395 time_t death = 0; 1396 struct sshkey **keys = NULL, *k; 1397 Identity *id; 1398 struct dest_constraint *dest_constraints = NULL; 1399 size_t ndest_constraints = 0; 1400 1401 debug2_f("entering"); 1402 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1403 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1404 error_fr(r, "parse"); 1405 goto send; 1406 } 1407 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1408 NULL, &dest_constraints, &ndest_constraints) != 0) { 1409 error_f("failed to parse constraints"); 1410 goto send; 1411 } 1412 if (realpath(provider, canonical_provider) == NULL) { 1413 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1414 provider, strerror(errno)); 1415 goto send; 1416 } 1417 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1418 verbose("refusing PKCS#11 add of \"%.100s\": " 1419 "provider not allowed", canonical_provider); 1420 goto send; 1421 } 1422 debug_f("add %.100s", canonical_provider); 1423 if (lifetime && !death) 1424 death = monotime() + lifetime; 1425 1426 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1427 for (i = 0; i < count; i++) { 1428 k = keys[i]; 1429 if (lookup_identity(k) == NULL) { 1430 id = xcalloc(1, sizeof(Identity)); 1431 id->key = k; 1432 keys[i] = NULL; /* transferred */ 1433 id->provider = xstrdup(canonical_provider); 1434 if (*comments[i] != '\0') { 1435 id->comment = comments[i]; 1436 comments[i] = NULL; /* transferred */ 1437 } else { 1438 id->comment = xstrdup(canonical_provider); 1439 } 1440 id->death = death; 1441 id->confirm = confirm; 1442 id->dest_constraints = dest_constraints; 1443 id->ndest_constraints = ndest_constraints; 1444 dest_constraints = NULL; /* transferred */ 1445 ndest_constraints = 0; 1446 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1447 idtab->nentries++; 1448 success = 1; 1449 } 1450 /* XXX update constraints for existing keys */ 1451 sshkey_free(keys[i]); 1452 free(comments[i]); 1453 } 1454 send: 1455 free(pin); 1456 free(provider); 1457 free(keys); 1458 free(comments); 1459 free_dest_constraints(dest_constraints, ndest_constraints); 1460 send_status(e, success); 1461 } 1462 1463 static void 1464 process_remove_smartcard_key(SocketEntry *e) 1465 { 1466 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1467 int r, success = 0; 1468 Identity *id, *nxt; 1469 1470 debug2_f("entering"); 1471 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1472 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1473 error_fr(r, "parse"); 1474 goto send; 1475 } 1476 free(pin); 1477 1478 if (realpath(provider, canonical_provider) == NULL) { 1479 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1480 provider, strerror(errno)); 1481 goto send; 1482 } 1483 1484 debug_f("remove %.100s", canonical_provider); 1485 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1486 nxt = TAILQ_NEXT(id, next); 1487 /* Skip file--based keys */ 1488 if (id->provider == NULL) 1489 continue; 1490 if (!strcmp(canonical_provider, id->provider)) { 1491 TAILQ_REMOVE(&idtab->idlist, id, next); 1492 free_identity(id); 1493 idtab->nentries--; 1494 } 1495 } 1496 if (pkcs11_del_provider(canonical_provider) == 0) 1497 success = 1; 1498 else 1499 error_f("pkcs11_del_provider failed"); 1500 send: 1501 free(provider); 1502 send_status(e, success); 1503 } 1504 #endif /* ENABLE_PKCS11 */ 1505 1506 static int 1507 process_ext_session_bind(SocketEntry *e) 1508 { 1509 int r, sid_match, key_match; 1510 struct sshkey *key = NULL; 1511 struct sshbuf *sid = NULL, *sig = NULL; 1512 char *fp = NULL; 1513 size_t i; 1514 u_char fwd = 0; 1515 1516 debug2_f("entering"); 1517 if ((r = sshkey_froms(e->request, &key)) != 0 || 1518 (r = sshbuf_froms(e->request, &sid)) != 0 || 1519 (r = sshbuf_froms(e->request, &sig)) != 0 || 1520 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1521 error_fr(r, "parse"); 1522 goto out; 1523 } 1524 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1525 SSH_FP_DEFAULT)) == NULL) 1526 fatal_f("fingerprint failed"); 1527 /* check signature with hostkey on session ID */ 1528 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1529 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1530 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1531 goto out; 1532 } 1533 /* check whether sid/key already recorded */ 1534 for (i = 0; i < e->nsession_ids; i++) { 1535 if (!e->session_ids[i].forwarded) { 1536 error_f("attempt to bind session ID to socket " 1537 "previously bound for authentication attempt"); 1538 r = -1; 1539 goto out; 1540 } 1541 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1542 key_match = sshkey_equal(key, e->session_ids[i].key); 1543 if (sid_match && key_match) { 1544 debug_f("session ID already recorded for %s %s", 1545 sshkey_type(key), fp); 1546 r = 0; 1547 goto out; 1548 } else if (sid_match) { 1549 error_f("session ID recorded against different key " 1550 "for %s %s", sshkey_type(key), fp); 1551 r = -1; 1552 goto out; 1553 } 1554 /* 1555 * new sid with previously-seen key can happen, e.g. multiple 1556 * connections to the same host. 1557 */ 1558 } 1559 /* record new key/sid */ 1560 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1561 error_f("too many session IDs recorded"); 1562 goto out; 1563 } 1564 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1565 e->nsession_ids + 1, sizeof(*e->session_ids)); 1566 i = e->nsession_ids++; 1567 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1568 AGENT_MAX_SESSION_IDS); 1569 e->session_ids[i].key = key; 1570 e->session_ids[i].forwarded = fwd != 0; 1571 key = NULL; /* transferred */ 1572 /* can't transfer sid; it's refcounted and scoped to request's life */ 1573 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1574 fatal_f("sshbuf_new"); 1575 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1576 fatal_fr(r, "sshbuf_putb session ID"); 1577 /* success */ 1578 r = 0; 1579 out: 1580 free(fp); 1581 sshkey_free(key); 1582 sshbuf_free(sid); 1583 sshbuf_free(sig); 1584 return r == 0 ? 1 : 0; 1585 } 1586 1587 static void 1588 process_extension(SocketEntry *e) 1589 { 1590 int r, success = 0; 1591 char *name; 1592 1593 debug2_f("entering"); 1594 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1595 error_fr(r, "parse"); 1596 goto send; 1597 } 1598 if (strcmp(name, "session-bind@openssh.com") == 0) 1599 success = process_ext_session_bind(e); 1600 else 1601 debug_f("unsupported extension \"%s\"", name); 1602 free(name); 1603 send: 1604 send_status(e, success); 1605 } 1606 /* 1607 * dispatch incoming message. 1608 * returns 1 on success, 0 for incomplete messages or -1 on error. 1609 */ 1610 static int 1611 process_message(u_int socknum) 1612 { 1613 u_int msg_len; 1614 u_char type; 1615 const u_char *cp; 1616 int r; 1617 SocketEntry *e; 1618 1619 if (socknum >= sockets_alloc) 1620 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1621 e = &sockets[socknum]; 1622 1623 if (sshbuf_len(e->input) < 5) 1624 return 0; /* Incomplete message header. */ 1625 cp = sshbuf_ptr(e->input); 1626 msg_len = PEEK_U32(cp); 1627 if (msg_len > AGENT_MAX_LEN) { 1628 debug_f("socket %u (fd=%d) message too long %u > %u", 1629 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1630 return -1; 1631 } 1632 if (sshbuf_len(e->input) < msg_len + 4) 1633 return 0; /* Incomplete message body. */ 1634 1635 /* move the current input to e->request */ 1636 sshbuf_reset(e->request); 1637 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1638 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1639 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1640 r == SSH_ERR_STRING_TOO_LARGE) { 1641 error_fr(r, "parse"); 1642 return -1; 1643 } 1644 fatal_fr(r, "parse"); 1645 } 1646 1647 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1648 1649 /* check whether agent is locked */ 1650 if (locked && type != SSH_AGENTC_UNLOCK) { 1651 sshbuf_reset(e->request); 1652 switch (type) { 1653 case SSH2_AGENTC_REQUEST_IDENTITIES: 1654 /* send empty lists */ 1655 no_identities(e); 1656 break; 1657 default: 1658 /* send a fail message for all other request types */ 1659 send_status(e, 0); 1660 } 1661 return 1; 1662 } 1663 1664 switch (type) { 1665 case SSH_AGENTC_LOCK: 1666 case SSH_AGENTC_UNLOCK: 1667 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1668 break; 1669 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1670 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1671 break; 1672 /* ssh2 */ 1673 case SSH2_AGENTC_SIGN_REQUEST: 1674 process_sign_request2(e); 1675 break; 1676 case SSH2_AGENTC_REQUEST_IDENTITIES: 1677 process_request_identities(e); 1678 break; 1679 case SSH2_AGENTC_ADD_IDENTITY: 1680 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1681 process_add_identity(e); 1682 break; 1683 case SSH2_AGENTC_REMOVE_IDENTITY: 1684 process_remove_identity(e); 1685 break; 1686 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1687 process_remove_all_identities(e); 1688 break; 1689 #ifdef ENABLE_PKCS11 1690 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1691 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1692 process_add_smartcard_key(e); 1693 break; 1694 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1695 process_remove_smartcard_key(e); 1696 break; 1697 #endif /* ENABLE_PKCS11 */ 1698 case SSH_AGENTC_EXTENSION: 1699 process_extension(e); 1700 break; 1701 default: 1702 /* Unknown message. Respond with failure. */ 1703 error("Unknown message %d", type); 1704 sshbuf_reset(e->request); 1705 send_status(e, 0); 1706 break; 1707 } 1708 return 1; 1709 } 1710 1711 static void 1712 new_socket(sock_type type, int fd) 1713 { 1714 u_int i, old_alloc, new_alloc; 1715 1716 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1717 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1718 if (type == AUTH_CONNECTION) { 1719 debug("xcount %d -> %d", xcount, xcount + 1); 1720 ++xcount; 1721 } 1722 set_nonblock(fd); 1723 1724 if (fd > max_fd) 1725 max_fd = fd; 1726 1727 for (i = 0; i < sockets_alloc; i++) 1728 if (sockets[i].type == AUTH_UNUSED) { 1729 sockets[i].fd = fd; 1730 if ((sockets[i].input = sshbuf_new()) == NULL || 1731 (sockets[i].output = sshbuf_new()) == NULL || 1732 (sockets[i].request = sshbuf_new()) == NULL) 1733 fatal_f("sshbuf_new failed"); 1734 sockets[i].type = type; 1735 return; 1736 } 1737 old_alloc = sockets_alloc; 1738 new_alloc = sockets_alloc + 10; 1739 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1740 sizeof(sockets[0])); 1741 for (i = old_alloc; i < new_alloc; i++) 1742 sockets[i].type = AUTH_UNUSED; 1743 sockets_alloc = new_alloc; 1744 sockets[old_alloc].fd = fd; 1745 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1746 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1747 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1748 fatal_f("sshbuf_new failed"); 1749 sockets[old_alloc].type = type; 1750 } 1751 1752 static int 1753 handle_socket_read(u_int socknum) 1754 { 1755 struct sockaddr_un sunaddr; 1756 socklen_t slen; 1757 uid_t euid; 1758 gid_t egid; 1759 int fd; 1760 1761 slen = sizeof(sunaddr); 1762 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1763 if (fd == -1) { 1764 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1765 return -1; 1766 } 1767 if (getpeereid(fd, &euid, &egid) == -1) { 1768 error("getpeereid %d failed: %s", fd, strerror(errno)); 1769 close(fd); 1770 return -1; 1771 } 1772 if ((euid != 0) && (getuid() != euid)) { 1773 error("uid mismatch: peer euid %u != uid %u", 1774 (u_int) euid, (u_int) getuid()); 1775 close(fd); 1776 return -1; 1777 } 1778 new_socket(AUTH_CONNECTION, fd); 1779 return 0; 1780 } 1781 1782 static int 1783 handle_conn_read(u_int socknum) 1784 { 1785 char buf[AGENT_RBUF_LEN]; 1786 ssize_t len; 1787 int r; 1788 1789 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1790 if (len == -1) { 1791 if (errno == EAGAIN || errno == EINTR) 1792 return 0; 1793 error_f("read error on socket %u (fd %d): %s", 1794 socknum, sockets[socknum].fd, strerror(errno)); 1795 } 1796 return -1; 1797 } 1798 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1799 fatal_fr(r, "compose"); 1800 explicit_bzero(buf, sizeof(buf)); 1801 for (;;) { 1802 if ((r = process_message(socknum)) == -1) 1803 return -1; 1804 else if (r == 0) 1805 break; 1806 } 1807 return 0; 1808 } 1809 1810 static int 1811 handle_conn_write(u_int socknum) 1812 { 1813 ssize_t len; 1814 int r; 1815 1816 if (sshbuf_len(sockets[socknum].output) == 0) 1817 return 0; /* shouldn't happen */ 1818 if ((len = write(sockets[socknum].fd, 1819 sshbuf_ptr(sockets[socknum].output), 1820 sshbuf_len(sockets[socknum].output))) <= 0) { 1821 if (len == -1) { 1822 if (errno == EAGAIN || errno == EINTR) 1823 return 0; 1824 error_f("read error on socket %u (fd %d): %s", 1825 socknum, sockets[socknum].fd, strerror(errno)); 1826 } 1827 return -1; 1828 } 1829 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1830 fatal_fr(r, "consume"); 1831 return 0; 1832 } 1833 1834 static void 1835 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1836 { 1837 size_t i; 1838 u_int socknum, activefds = npfd; 1839 1840 for (i = 0; i < npfd; i++) { 1841 if (pfd[i].revents == 0) 1842 continue; 1843 /* Find sockets entry */ 1844 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1845 if (sockets[socknum].type != AUTH_SOCKET && 1846 sockets[socknum].type != AUTH_CONNECTION) 1847 continue; 1848 if (pfd[i].fd == sockets[socknum].fd) 1849 break; 1850 } 1851 if (socknum >= sockets_alloc) { 1852 error_f("no socket for fd %d", pfd[i].fd); 1853 continue; 1854 } 1855 /* Process events */ 1856 switch (sockets[socknum].type) { 1857 case AUTH_SOCKET: 1858 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1859 break; 1860 if (npfd > maxfds) { 1861 debug3("out of fds (active %u >= limit %u); " 1862 "skipping accept", activefds, maxfds); 1863 break; 1864 } 1865 if (handle_socket_read(socknum) == 0) 1866 activefds++; 1867 break; 1868 case AUTH_CONNECTION: 1869 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1870 handle_conn_read(socknum) != 0) 1871 goto close_sock; 1872 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1873 handle_conn_write(socknum) != 0) { 1874 close_sock: 1875 if (activefds == 0) 1876 fatal("activefds == 0 at close_sock"); 1877 close_socket(&sockets[socknum]); 1878 activefds--; 1879 break; 1880 } 1881 break; 1882 default: 1883 break; 1884 } 1885 } 1886 } 1887 1888 static int 1889 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1890 { 1891 struct pollfd *pfd = *pfdp; 1892 size_t i, j, npfd = 0; 1893 time_t deadline; 1894 int r; 1895 1896 /* Count active sockets */ 1897 for (i = 0; i < sockets_alloc; i++) { 1898 switch (sockets[i].type) { 1899 case AUTH_SOCKET: 1900 case AUTH_CONNECTION: 1901 npfd++; 1902 break; 1903 case AUTH_UNUSED: 1904 break; 1905 default: 1906 fatal("Unknown socket type %d", sockets[i].type); 1907 break; 1908 } 1909 } 1910 if (npfd != *npfdp && 1911 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1912 fatal_f("recallocarray failed"); 1913 *pfdp = pfd; 1914 *npfdp = npfd; 1915 1916 for (i = j = 0; i < sockets_alloc; i++) { 1917 switch (sockets[i].type) { 1918 case AUTH_SOCKET: 1919 if (npfd > maxfds) { 1920 debug3("out of fds (active %zu >= limit %u); " 1921 "skipping arming listener", npfd, maxfds); 1922 break; 1923 } 1924 pfd[j].fd = sockets[i].fd; 1925 pfd[j].revents = 0; 1926 pfd[j].events = POLLIN; 1927 j++; 1928 break; 1929 case AUTH_CONNECTION: 1930 pfd[j].fd = sockets[i].fd; 1931 pfd[j].revents = 0; 1932 /* 1933 * Only prepare to read if we can handle a full-size 1934 * input read buffer and enqueue a max size reply.. 1935 */ 1936 if ((r = sshbuf_check_reserve(sockets[i].input, 1937 AGENT_RBUF_LEN)) == 0 && 1938 (r = sshbuf_check_reserve(sockets[i].output, 1939 AGENT_MAX_LEN)) == 0) 1940 pfd[j].events = POLLIN; 1941 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1942 fatal_fr(r, "reserve"); 1943 if (sshbuf_len(sockets[i].output) > 0) 1944 pfd[j].events |= POLLOUT; 1945 j++; 1946 break; 1947 default: 1948 break; 1949 } 1950 } 1951 deadline = reaper(); 1952 if (parent_alive_interval != 0) 1953 deadline = (deadline == 0) ? parent_alive_interval : 1954 MINIMUM(deadline, parent_alive_interval); 1955 if (deadline == 0) { 1956 *timeoutp = -1; /* INFTIM */ 1957 } else { 1958 if (deadline > INT_MAX / 1000) 1959 *timeoutp = INT_MAX / 1000; 1960 else 1961 *timeoutp = deadline * 1000; 1962 } 1963 return (1); 1964 } 1965 1966 static void 1967 cleanup_socket(void) 1968 { 1969 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1970 return; 1971 debug_f("cleanup"); 1972 if (socket_name[0]) 1973 unlink(socket_name); 1974 if (socket_dir[0]) 1975 rmdir(socket_dir); 1976 } 1977 1978 void 1979 cleanup_exit(int i) 1980 { 1981 cleanup_socket(); 1982 _exit(i); 1983 } 1984 1985 static void 1986 cleanup_handler(int sig) 1987 { 1988 cleanup_socket(); 1989 #ifdef ENABLE_PKCS11 1990 pkcs11_terminate(); 1991 #endif 1992 _exit(2); 1993 } 1994 1995 static void 1996 check_parent_exists(void) 1997 { 1998 /* 1999 * If our parent has exited then getppid() will return (pid_t)1, 2000 * so testing for that should be safe. 2001 */ 2002 if (parent_pid != -1 && getppid() != parent_pid) { 2003 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2004 cleanup_socket(); 2005 _exit(2); 2006 } 2007 } 2008 2009 static void 2010 usage(void) 2011 { 2012 fprintf(stderr, 2013 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2014 " [-O option] [-P allowed_providers] [-t life]\n" 2015 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2016 " [-P allowed_providers] [-t life] command [arg ...]\n" 2017 " ssh-agent [-c | -s] -k\n"); 2018 exit(1); 2019 } 2020 2021 int 2022 main(int ac, char **av) 2023 { 2024 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2025 int sock, ch, result, saved_errno; 2026 char *shell, *format, *pidstr, *agentsocket = NULL; 2027 #ifdef HAVE_SETRLIMIT 2028 struct rlimit rlim; 2029 #endif 2030 extern int optind; 2031 extern char *optarg; 2032 pid_t pid; 2033 char pidstrbuf[1 + 3 * sizeof pid]; 2034 size_t len; 2035 mode_t prev_mask; 2036 int timeout = -1; /* INFTIM */ 2037 struct pollfd *pfd = NULL; 2038 size_t npfd = 0; 2039 u_int maxfds; 2040 2041 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2042 sanitise_stdfd(); 2043 2044 /* drop */ 2045 setegid(getgid()); 2046 setgid(getgid()); 2047 setuid(geteuid()); 2048 2049 platform_disable_tracing(0); /* strict=no */ 2050 2051 #ifdef RLIMIT_NOFILE 2052 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2053 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2054 #endif 2055 2056 __progname = ssh_get_progname(av[0]); 2057 seed_rng(); 2058 2059 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2060 switch (ch) { 2061 case 'E': 2062 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2063 if (fingerprint_hash == -1) 2064 fatal("Invalid hash algorithm \"%s\"", optarg); 2065 break; 2066 case 'c': 2067 if (s_flag) 2068 usage(); 2069 c_flag++; 2070 break; 2071 case 'k': 2072 k_flag++; 2073 break; 2074 case 'O': 2075 if (strcmp(optarg, "no-restrict-websafe") == 0) 2076 restrict_websafe = 0; 2077 else 2078 fatal("Unknown -O option"); 2079 break; 2080 case 'P': 2081 if (allowed_providers != NULL) 2082 fatal("-P option already specified"); 2083 allowed_providers = xstrdup(optarg); 2084 break; 2085 case 's': 2086 if (c_flag) 2087 usage(); 2088 s_flag++; 2089 break; 2090 case 'd': 2091 if (d_flag || D_flag) 2092 usage(); 2093 d_flag++; 2094 break; 2095 case 'D': 2096 if (d_flag || D_flag) 2097 usage(); 2098 D_flag++; 2099 break; 2100 case 'a': 2101 agentsocket = optarg; 2102 break; 2103 case 't': 2104 if ((lifetime = convtime(optarg)) == -1) { 2105 fprintf(stderr, "Invalid lifetime\n"); 2106 usage(); 2107 } 2108 break; 2109 case 'x': 2110 xcount = 0; 2111 break; 2112 default: 2113 usage(); 2114 } 2115 } 2116 ac -= optind; 2117 av += optind; 2118 2119 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2120 usage(); 2121 2122 if (allowed_providers == NULL) 2123 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2124 2125 if (ac == 0 && !c_flag && !s_flag) { 2126 shell = getenv("SHELL"); 2127 if (shell != NULL && (len = strlen(shell)) > 2 && 2128 strncmp(shell + len - 3, "csh", 3) == 0) 2129 c_flag = 1; 2130 } 2131 if (k_flag) { 2132 const char *errstr = NULL; 2133 2134 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2135 if (pidstr == NULL) { 2136 fprintf(stderr, "%s not set, cannot kill agent\n", 2137 SSH_AGENTPID_ENV_NAME); 2138 exit(1); 2139 } 2140 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2141 if (errstr) { 2142 fprintf(stderr, 2143 "%s=\"%s\", which is not a good PID: %s\n", 2144 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2145 exit(1); 2146 } 2147 if (kill(pid, SIGTERM) == -1) { 2148 perror("kill"); 2149 exit(1); 2150 } 2151 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2152 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2153 printf(format, SSH_AGENTPID_ENV_NAME); 2154 printf("echo Agent pid %ld killed;\n", (long)pid); 2155 exit(0); 2156 } 2157 2158 /* 2159 * Minimum file descriptors: 2160 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2161 * a few spare for libc / stack protectors / sanitisers, etc. 2162 */ 2163 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2164 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2165 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2166 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2167 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2168 2169 parent_pid = getpid(); 2170 2171 if (agentsocket == NULL) { 2172 /* Create private directory for agent socket */ 2173 mktemp_proto(socket_dir, sizeof(socket_dir)); 2174 if (mkdtemp(socket_dir) == NULL) { 2175 perror("mkdtemp: private socket dir"); 2176 exit(1); 2177 } 2178 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2179 (long)parent_pid); 2180 } else { 2181 /* Try to use specified agent socket */ 2182 socket_dir[0] = '\0'; 2183 strlcpy(socket_name, agentsocket, sizeof socket_name); 2184 } 2185 2186 /* 2187 * Create socket early so it will exist before command gets run from 2188 * the parent. 2189 */ 2190 prev_mask = umask(0177); 2191 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2192 if (sock < 0) { 2193 /* XXX - unix_listener() calls error() not perror() */ 2194 *socket_name = '\0'; /* Don't unlink any existing file */ 2195 cleanup_exit(1); 2196 } 2197 umask(prev_mask); 2198 2199 /* 2200 * Fork, and have the parent execute the command, if any, or present 2201 * the socket data. The child continues as the authentication agent. 2202 */ 2203 if (D_flag || d_flag) { 2204 log_init(__progname, 2205 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2206 SYSLOG_FACILITY_AUTH, 1); 2207 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2208 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2209 SSH_AUTHSOCKET_ENV_NAME); 2210 printf("echo Agent pid %ld;\n", (long)parent_pid); 2211 fflush(stdout); 2212 goto skip; 2213 } 2214 pid = fork(); 2215 if (pid == -1) { 2216 perror("fork"); 2217 cleanup_exit(1); 2218 } 2219 if (pid != 0) { /* Parent - execute the given command. */ 2220 close(sock); 2221 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2222 if (ac == 0) { 2223 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2224 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2225 SSH_AUTHSOCKET_ENV_NAME); 2226 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2227 SSH_AGENTPID_ENV_NAME); 2228 printf("echo Agent pid %ld;\n", (long)pid); 2229 exit(0); 2230 } 2231 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2232 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2233 perror("setenv"); 2234 exit(1); 2235 } 2236 execvp(av[0], av); 2237 perror(av[0]); 2238 exit(1); 2239 } 2240 /* child */ 2241 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2242 2243 if (setsid() == -1) { 2244 error("setsid: %s", strerror(errno)); 2245 cleanup_exit(1); 2246 } 2247 2248 (void)chdir("/"); 2249 if (stdfd_devnull(1, 1, 1) == -1) 2250 error_f("stdfd_devnull failed"); 2251 2252 #ifdef HAVE_SETRLIMIT 2253 /* deny core dumps, since memory contains unencrypted private keys */ 2254 rlim.rlim_cur = rlim.rlim_max = 0; 2255 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2256 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2257 cleanup_exit(1); 2258 } 2259 #endif 2260 2261 skip: 2262 2263 cleanup_pid = getpid(); 2264 2265 #ifdef ENABLE_PKCS11 2266 pkcs11_init(0); 2267 #endif 2268 new_socket(AUTH_SOCKET, sock); 2269 if (ac > 0) 2270 parent_alive_interval = 10; 2271 idtab_init(); 2272 ssh_signal(SIGPIPE, SIG_IGN); 2273 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2274 ssh_signal(SIGHUP, cleanup_handler); 2275 ssh_signal(SIGTERM, cleanup_handler); 2276 2277 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2278 fatal("%s: pledge: %s", __progname, strerror(errno)); 2279 platform_pledge_agent(); 2280 2281 while (1) { 2282 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2283 result = poll(pfd, npfd, timeout); 2284 saved_errno = errno; 2285 if (parent_alive_interval != 0) 2286 check_parent_exists(); 2287 (void) reaper(); /* remove expired keys */ 2288 if (result == -1) { 2289 if (saved_errno == EINTR) 2290 continue; 2291 fatal("poll: %s", strerror(saved_errno)); 2292 } else if (result > 0) 2293 after_poll(pfd, npfd, maxfds); 2294 } 2295 /* NOTREACHED */ 2296 } 2297