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 /* 193 * Client connection count; incremented in new_socket() and decremented in 194 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 195 * normally initialized to 1, it will never reach 0. However, if the -x 196 * option is specified, it is initialized to 0 in main(); in that case, 197 * ssh-agent will exit as soon as it has had at least one client but no 198 * longer has any. 199 */ 200 static int xcount = 1; 201 202 static void 203 close_socket(SocketEntry *e) 204 { 205 size_t i; 206 int last = 0; 207 208 if (e->type == AUTH_CONNECTION) { 209 debug("xcount %d -> %d", xcount, xcount - 1); 210 if (--xcount == 0) 211 last = 1; 212 } 213 close(e->fd); 214 sshbuf_free(e->input); 215 sshbuf_free(e->output); 216 sshbuf_free(e->request); 217 for (i = 0; i < e->nsession_ids; i++) { 218 sshkey_free(e->session_ids[i].key); 219 sshbuf_free(e->session_ids[i].sid); 220 } 221 free(e->session_ids); 222 memset(e, '\0', sizeof(*e)); 223 e->fd = -1; 224 e->type = AUTH_UNUSED; 225 if (last) 226 cleanup_exit(0); 227 } 228 229 static void 230 idtab_init(void) 231 { 232 idtab = xcalloc(1, sizeof(*idtab)); 233 TAILQ_INIT(&idtab->idlist); 234 idtab->nentries = 0; 235 } 236 237 static void 238 free_dest_constraint_hop(struct dest_constraint_hop *dch) 239 { 240 u_int i; 241 242 if (dch == NULL) 243 return; 244 free(dch->user); 245 free(dch->hostname); 246 for (i = 0; i < dch->nkeys; i++) 247 sshkey_free(dch->keys[i]); 248 free(dch->keys); 249 free(dch->key_is_ca); 250 } 251 252 static void 253 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 254 { 255 size_t i; 256 257 for (i = 0; i < ndcs; i++) { 258 free_dest_constraint_hop(&dcs[i].from); 259 free_dest_constraint_hop(&dcs[i].to); 260 } 261 free(dcs); 262 } 263 264 static void 265 free_identity(Identity *id) 266 { 267 sshkey_free(id->key); 268 free(id->provider); 269 free(id->comment); 270 free(id->sk_provider); 271 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 272 free(id); 273 } 274 275 /* 276 * Match 'key' against the key/CA list in a destination constraint hop 277 * Returns 0 on success or -1 otherwise. 278 */ 279 static int 280 match_key_hop(const char *tag, const struct sshkey *key, 281 const struct dest_constraint_hop *dch) 282 { 283 const char *reason = NULL; 284 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 285 u_int i; 286 char *fp; 287 288 if (key == NULL) 289 return -1; 290 /* XXX logspam */ 291 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 292 SSH_FP_DEFAULT)) == NULL) 293 fatal_f("fingerprint failed"); 294 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 295 tag, hostname, sshkey_type(key), fp, dch->nkeys); 296 free(fp); 297 for (i = 0; i < dch->nkeys; i++) { 298 if (dch->keys[i] == NULL) 299 return -1; 300 /* XXX logspam */ 301 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 302 SSH_FP_DEFAULT)) == NULL) 303 fatal_f("fingerprint failed"); 304 debug3_f("%s: key %u: %s%s %s", tag, i, 305 dch->key_is_ca[i] ? "CA " : "", 306 sshkey_type(dch->keys[i]), fp); 307 free(fp); 308 if (!sshkey_is_cert(key)) { 309 /* plain key */ 310 if (dch->key_is_ca[i] || 311 !sshkey_equal(key, dch->keys[i])) 312 continue; 313 return 0; 314 } 315 /* certificate */ 316 if (!dch->key_is_ca[i]) 317 continue; 318 if (key->cert == NULL || key->cert->signature_key == NULL) 319 return -1; /* shouldn't happen */ 320 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 321 continue; 322 if (sshkey_cert_check_host(key, hostname, 1, 323 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 324 debug_f("cert %s / hostname %s rejected: %s", 325 key->cert->key_id, hostname, reason); 326 continue; 327 } 328 return 0; 329 } 330 return -1; 331 } 332 333 /* Check destination constraints on an identity against the hostkey/user */ 334 static int 335 permitted_by_dest_constraints(const struct sshkey *fromkey, 336 const struct sshkey *tokey, Identity *id, const char *user, 337 const char **hostnamep) 338 { 339 size_t i; 340 struct dest_constraint *d; 341 342 if (hostnamep != NULL) 343 *hostnamep = NULL; 344 for (i = 0; i < id->ndest_constraints; i++) { 345 d = id->dest_constraints + i; 346 /* XXX remove logspam */ 347 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 348 i, d->from.user ? d->from.user : "", 349 d->from.user ? "@" : "", 350 d->from.hostname ? d->from.hostname : "(ORIGIN)", 351 d->from.nkeys, 352 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 353 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 354 355 /* Match 'from' key */ 356 if (fromkey == NULL) { 357 /* We are matching the first hop */ 358 if (d->from.hostname != NULL || d->from.nkeys != 0) 359 continue; 360 } else if (match_key_hop("from", fromkey, &d->from) != 0) 361 continue; 362 363 /* Match 'to' key */ 364 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 365 continue; 366 367 /* Match user if specified */ 368 if (d->to.user != NULL && user != NULL && 369 !match_pattern(user, d->to.user)) 370 continue; 371 372 /* successfully matched this constraint */ 373 if (hostnamep != NULL) 374 *hostnamep = d->to.hostname; 375 debug2_f("allowed for hostname %s", 376 d->to.hostname == NULL ? "*" : d->to.hostname); 377 return 0; 378 } 379 /* no match */ 380 debug2_f("%s identity \"%s\" not permitted for this destination", 381 sshkey_type(id->key), id->comment); 382 return -1; 383 } 384 385 /* 386 * Check whether hostkeys on a SocketEntry and the optionally specified user 387 * are permitted by the destination constraints on the Identity. 388 * Returns 0 on success or -1 otherwise. 389 */ 390 static int 391 identity_permitted(Identity *id, SocketEntry *e, char *user, 392 const char **forward_hostnamep, const char **last_hostnamep) 393 { 394 size_t i; 395 const char **hp; 396 struct hostkey_sid *hks; 397 const struct sshkey *fromkey = NULL; 398 const char *test_user; 399 char *fp1, *fp2; 400 401 /* XXX remove logspam */ 402 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 403 "%zu constraints", sshkey_type(id->key), id->comment, 404 e->nsession_ids, id->ndest_constraints); 405 if (id->ndest_constraints == 0) 406 return 0; /* unconstrained */ 407 if (e->nsession_ids == 0) 408 return 0; /* local use */ 409 /* 410 * Walk through the hops recorded by session_id and try to find a 411 * constraint that satisfies each. 412 */ 413 for (i = 0; i < e->nsession_ids; i++) { 414 hks = e->session_ids + i; 415 if (hks->key == NULL) 416 fatal_f("internal error: no bound key"); 417 /* XXX remove logspam */ 418 fp1 = fp2 = NULL; 419 if (fromkey != NULL && 420 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 421 SSH_FP_DEFAULT)) == NULL) 422 fatal_f("fingerprint failed"); 423 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 424 SSH_FP_DEFAULT)) == NULL) 425 fatal_f("fingerprint failed"); 426 debug3_f("socketentry fd=%d, entry %zu %s, " 427 "from hostkey %s %s to user %s hostkey %s %s", 428 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 429 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 430 fromkey ? fp1 : "", user ? user : "(ANY)", 431 sshkey_type(hks->key), fp2); 432 free(fp1); 433 free(fp2); 434 /* 435 * Record the hostnames for the initial forwarding and 436 * the final destination. 437 */ 438 hp = NULL; 439 if (i == e->nsession_ids - 1) 440 hp = last_hostnamep; 441 else if (i == 0) 442 hp = forward_hostnamep; 443 /* Special handling for final recorded binding */ 444 test_user = NULL; 445 if (i == e->nsession_ids - 1) { 446 /* Can only check user at final hop */ 447 test_user = user; 448 /* 449 * user is only presented for signature requests. 450 * If this is the case, make sure last binding is not 451 * for a forwarding. 452 */ 453 if (hks->forwarded && user != NULL) { 454 error_f("tried to sign on forwarding hop"); 455 return -1; 456 } 457 } else if (!hks->forwarded) { 458 error_f("tried to forward though signing bind"); 459 return -1; 460 } 461 if (permitted_by_dest_constraints(fromkey, hks->key, id, 462 test_user, hp) != 0) 463 return -1; 464 fromkey = hks->key; 465 } 466 /* 467 * Another special case: if the last bound session ID was for a 468 * forwarding, and this function is not being called to check a sign 469 * request (i.e. no 'user' supplied), then only permit the key if 470 * there is a permission that would allow it to be used at another 471 * destination. This hides keys that are allowed to be used to 472 * authenticate *to* a host but not permitted for *use* beyond it. 473 */ 474 hks = &e->session_ids[e->nsession_ids - 1]; 475 if (hks->forwarded && user == NULL && 476 permitted_by_dest_constraints(hks->key, NULL, id, 477 NULL, NULL) != 0) { 478 debug3_f("key permitted at host but not after"); 479 return -1; 480 } 481 482 /* success */ 483 return 0; 484 } 485 486 /* return matching private key for given public key */ 487 static Identity * 488 lookup_identity(struct sshkey *key) 489 { 490 Identity *id; 491 492 TAILQ_FOREACH(id, &idtab->idlist, next) { 493 if (sshkey_equal(key, id->key)) 494 return (id); 495 } 496 return (NULL); 497 } 498 499 /* Check confirmation of keysign request */ 500 static int 501 confirm_key(Identity *id, const char *extra) 502 { 503 char *p; 504 int ret = -1; 505 506 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 507 if (p != NULL && 508 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 509 id->comment, p, 510 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 511 ret = 0; 512 free(p); 513 514 return (ret); 515 } 516 517 static void 518 send_status(SocketEntry *e, int success) 519 { 520 int r; 521 522 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 523 (r = sshbuf_put_u8(e->output, success ? 524 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 525 fatal_fr(r, "compose"); 526 } 527 528 /* send list of supported public keys to 'client' */ 529 static void 530 process_request_identities(SocketEntry *e) 531 { 532 Identity *id; 533 struct sshbuf *msg, *keys; 534 int r; 535 u_int nentries = 0; 536 537 debug2_f("entering"); 538 539 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 540 fatal_f("sshbuf_new failed"); 541 TAILQ_FOREACH(id, &idtab->idlist, next) { 542 /* identity not visible, don't include in response */ 543 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 544 continue; 545 if ((r = sshkey_puts_opts(id->key, keys, 546 SSHKEY_SERIALIZE_INFO)) != 0 || 547 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 548 error_fr(r, "compose key/comment"); 549 continue; 550 } 551 nentries++; 552 } 553 debug2_f("replying with %u allowed of %u available keys", 554 nentries, idtab->nentries); 555 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 556 (r = sshbuf_put_u32(msg, nentries)) != 0 || 557 (r = sshbuf_putb(msg, keys)) != 0) 558 fatal_fr(r, "compose"); 559 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 560 fatal_fr(r, "enqueue"); 561 sshbuf_free(msg); 562 sshbuf_free(keys); 563 } 564 565 566 static char * 567 agent_decode_alg(struct sshkey *key, u_int flags) 568 { 569 if (key->type == KEY_RSA) { 570 if (flags & SSH_AGENT_RSA_SHA2_256) 571 return "rsa-sha2-256"; 572 else if (flags & SSH_AGENT_RSA_SHA2_512) 573 return "rsa-sha2-512"; 574 } else if (key->type == KEY_RSA_CERT) { 575 if (flags & SSH_AGENT_RSA_SHA2_256) 576 return "rsa-sha2-256-cert-v01@openssh.com"; 577 else if (flags & SSH_AGENT_RSA_SHA2_512) 578 return "rsa-sha2-512-cert-v01@openssh.com"; 579 } 580 return NULL; 581 } 582 583 /* 584 * Attempt to parse the contents of a buffer as a SSH publickey userauth 585 * request, checking its contents for consistency and matching the embedded 586 * key against the one that is being used for signing. 587 * Note: does not modify msg buffer. 588 * Optionally extract the username, session ID and/or hostkey from the request. 589 */ 590 static int 591 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 592 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 593 { 594 struct sshbuf *b = NULL, *sess_id = NULL; 595 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 596 int r; 597 u_char t, sig_follows; 598 struct sshkey *mkey = NULL, *hostkey = NULL; 599 600 if (userp != NULL) 601 *userp = NULL; 602 if (sess_idp != NULL) 603 *sess_idp = NULL; 604 if (hostkeyp != NULL) 605 *hostkeyp = NULL; 606 if ((b = sshbuf_fromb(msg)) == NULL) 607 fatal_f("sshbuf_fromb"); 608 609 /* SSH userauth request */ 610 if ((r = sshbuf_froms(b, &sess_id)) != 0) 611 goto out; 612 if (sshbuf_len(sess_id) == 0) { 613 r = SSH_ERR_INVALID_FORMAT; 614 goto out; 615 } 616 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 617 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 618 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 619 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 620 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 621 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 622 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 623 goto out; 624 if (t != SSH2_MSG_USERAUTH_REQUEST || 625 sig_follows != 1 || 626 strcmp(service, "ssh-connection") != 0 || 627 !sshkey_equal(expected_key, mkey) || 628 sshkey_type_from_name(pkalg) != expected_key->type) { 629 r = SSH_ERR_INVALID_FORMAT; 630 goto out; 631 } 632 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 633 if ((r = sshkey_froms(b, &hostkey)) != 0) 634 goto out; 635 } else if (strcmp(method, "publickey") != 0) { 636 r = SSH_ERR_INVALID_FORMAT; 637 goto out; 638 } 639 if (sshbuf_len(b) != 0) { 640 r = SSH_ERR_INVALID_FORMAT; 641 goto out; 642 } 643 /* success */ 644 r = 0; 645 debug3_f("well formed userauth"); 646 if (userp != NULL) { 647 *userp = user; 648 user = NULL; 649 } 650 if (sess_idp != NULL) { 651 *sess_idp = sess_id; 652 sess_id = NULL; 653 } 654 if (hostkeyp != NULL) { 655 *hostkeyp = hostkey; 656 hostkey = NULL; 657 } 658 out: 659 sshbuf_free(b); 660 sshbuf_free(sess_id); 661 free(user); 662 free(service); 663 free(method); 664 free(pkalg); 665 sshkey_free(mkey); 666 sshkey_free(hostkey); 667 return r; 668 } 669 670 /* 671 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 672 * Note: does not modify buffer. 673 */ 674 static int 675 parse_sshsig_request(struct sshbuf *msg) 676 { 677 int r; 678 struct sshbuf *b; 679 680 if ((b = sshbuf_fromb(msg)) == NULL) 681 fatal_f("sshbuf_fromb"); 682 683 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 684 (r = sshbuf_consume(b, 6)) != 0 || 685 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 686 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 687 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 688 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 689 goto out; 690 if (sshbuf_len(b) != 0) { 691 r = SSH_ERR_INVALID_FORMAT; 692 goto out; 693 } 694 /* success */ 695 r = 0; 696 out: 697 sshbuf_free(b); 698 return r; 699 } 700 701 /* 702 * This function inspects a message to be signed by a FIDO key that has a 703 * web-like application string (i.e. one that does not begin with "ssh:". 704 * It checks that the message is one of those expected for SSH operations 705 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 706 * for the web. 707 */ 708 static int 709 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 710 { 711 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 712 debug_f("signed data matches public key userauth request"); 713 return 1; 714 } 715 if (parse_sshsig_request(data) == 0) { 716 debug_f("signed data matches SSHSIG signature request"); 717 return 1; 718 } 719 720 /* XXX check CA signature operation */ 721 722 error("web-origin key attempting to sign non-SSH message"); 723 return 0; 724 } 725 726 static int 727 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 728 { 729 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 730 return SSH_ERR_INVALID_ARGUMENT; 731 if (sshbuf_len(a) != sshbuf_len(b)) 732 return SSH_ERR_INVALID_FORMAT; 733 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 734 return SSH_ERR_INVALID_FORMAT; 735 return 0; 736 } 737 738 /* ssh2 only */ 739 static void 740 process_sign_request2(SocketEntry *e) 741 { 742 u_char *signature = NULL; 743 size_t slen = 0; 744 u_int compat = 0, flags; 745 int r, ok = -1, retried = 0; 746 char *fp = NULL, *pin = NULL, *prompt = NULL; 747 char *user = NULL, *sig_dest = NULL; 748 const char *fwd_host = NULL, *dest_host = NULL; 749 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 750 struct sshkey *key = NULL, *hostkey = NULL; 751 struct identity *id; 752 struct notifier_ctx *notifier = NULL; 753 754 debug_f("entering"); 755 756 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 757 fatal_f("sshbuf_new failed"); 758 if ((r = sshkey_froms(e->request, &key)) != 0 || 759 (r = sshbuf_get_stringb(e->request, data)) != 0 || 760 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 761 error_fr(r, "parse"); 762 goto send; 763 } 764 765 if ((id = lookup_identity(key)) == NULL) { 766 verbose_f("%s key not found", sshkey_type(key)); 767 goto send; 768 } 769 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 770 SSH_FP_DEFAULT)) == NULL) 771 fatal_f("fingerprint failed"); 772 773 if (id->ndest_constraints != 0) { 774 if (e->nsession_ids == 0) { 775 logit_f("refusing use of destination-constrained key " 776 "to sign on unbound connection"); 777 goto send; 778 } 779 if (parse_userauth_request(data, key, &user, &sid, 780 &hostkey) != 0) { 781 logit_f("refusing use of destination-constrained key " 782 "to sign an unidentified signature"); 783 goto send; 784 } 785 /* XXX logspam */ 786 debug_f("user=%s", user); 787 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 788 goto send; 789 /* XXX display fwd_host/dest_host in askpass UI */ 790 /* 791 * Ensure that the session ID is the most recent one 792 * registered on the socket - it should have been bound by 793 * ssh immediately before userauth. 794 */ 795 if (buf_equal(sid, 796 e->session_ids[e->nsession_ids - 1].sid) != 0) { 797 error_f("unexpected session ID (%zu listed) on " 798 "signature request for target user %s with " 799 "key %s %s", e->nsession_ids, user, 800 sshkey_type(id->key), fp); 801 goto send; 802 } 803 /* 804 * Ensure that the hostkey embedded in the signature matches 805 * the one most recently bound to the socket. An exception is 806 * made for the initial forwarding hop. 807 */ 808 if (e->nsession_ids > 1 && hostkey == NULL) { 809 error_f("refusing use of destination-constrained key: " 810 "no hostkey recorded in signature for forwarded " 811 "connection"); 812 goto send; 813 } 814 if (hostkey != NULL && !sshkey_equal(hostkey, 815 e->session_ids[e->nsession_ids - 1].key)) { 816 error_f("refusing use of destination-constrained key: " 817 "mismatch between hostkey in request and most " 818 "recently bound session"); 819 goto send; 820 } 821 xasprintf(&sig_dest, "public key authentication request for " 822 "user \"%s\" to listed host", user); 823 } 824 if (id->confirm && confirm_key(id, sig_dest) != 0) { 825 verbose_f("user refused key"); 826 goto send; 827 } 828 if (sshkey_is_sk(id->key)) { 829 if (restrict_websafe && 830 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 831 !check_websafe_message_contents(key, data)) { 832 /* error already logged */ 833 goto send; 834 } 835 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 836 notifier = notify_start(0, 837 "Confirm user presence for key %s %s%s%s", 838 sshkey_type(id->key), fp, 839 sig_dest == NULL ? "" : "\n", 840 sig_dest == NULL ? "" : sig_dest); 841 } 842 } 843 retry_pin: 844 if ((r = sshkey_sign(id->key, &signature, &slen, 845 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 846 id->sk_provider, pin, compat)) != 0) { 847 debug_fr(r, "sshkey_sign"); 848 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 849 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 850 notify_complete(notifier, NULL); 851 notifier = NULL; 852 /* XXX include sig_dest */ 853 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 854 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 855 " and confirm user presence " : " ", 856 sshkey_type(id->key), fp); 857 pin = read_passphrase(prompt, RP_USE_ASKPASS); 858 retried = 1; 859 goto retry_pin; 860 } 861 error_fr(r, "sshkey_sign"); 862 goto send; 863 } 864 /* Success */ 865 ok = 0; 866 send: 867 debug_f("good signature"); 868 notify_complete(notifier, "User presence confirmed"); 869 870 if (ok == 0) { 871 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 872 (r = sshbuf_put_string(msg, signature, slen)) != 0) 873 fatal_fr(r, "compose"); 874 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 875 fatal_fr(r, "compose failure"); 876 877 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 878 fatal_fr(r, "enqueue"); 879 880 sshbuf_free(sid); 881 sshbuf_free(data); 882 sshbuf_free(msg); 883 sshkey_free(key); 884 sshkey_free(hostkey); 885 free(fp); 886 free(signature); 887 free(sig_dest); 888 free(user); 889 free(prompt); 890 if (pin != NULL) 891 freezero(pin, strlen(pin)); 892 } 893 894 /* shared */ 895 static void 896 process_remove_identity(SocketEntry *e) 897 { 898 int r, success = 0; 899 struct sshkey *key = NULL; 900 Identity *id; 901 902 debug2_f("entering"); 903 if ((r = sshkey_froms(e->request, &key)) != 0) { 904 error_fr(r, "parse key"); 905 goto done; 906 } 907 if ((id = lookup_identity(key)) == NULL) { 908 debug_f("key not found"); 909 goto done; 910 } 911 /* identity not visible, cannot be removed */ 912 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 913 goto done; /* error already logged */ 914 /* We have this key, free it. */ 915 if (idtab->nentries < 1) 916 fatal_f("internal error: nentries %d", idtab->nentries); 917 TAILQ_REMOVE(&idtab->idlist, id, next); 918 free_identity(id); 919 idtab->nentries--; 920 success = 1; 921 done: 922 sshkey_free(key); 923 send_status(e, success); 924 } 925 926 static void 927 process_remove_all_identities(SocketEntry *e) 928 { 929 Identity *id; 930 931 debug2_f("entering"); 932 /* Loop over all identities and clear the keys. */ 933 for (id = TAILQ_FIRST(&idtab->idlist); id; 934 id = TAILQ_FIRST(&idtab->idlist)) { 935 TAILQ_REMOVE(&idtab->idlist, id, next); 936 free_identity(id); 937 } 938 939 /* Mark that there are no identities. */ 940 idtab->nentries = 0; 941 942 /* Send success. */ 943 send_status(e, 1); 944 } 945 946 /* removes expired keys and returns number of seconds until the next expiry */ 947 static time_t 948 reaper(void) 949 { 950 time_t deadline = 0, now = monotime(); 951 Identity *id, *nxt; 952 953 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 954 nxt = TAILQ_NEXT(id, next); 955 if (id->death == 0) 956 continue; 957 if (now >= id->death) { 958 debug("expiring key '%s'", id->comment); 959 TAILQ_REMOVE(&idtab->idlist, id, next); 960 free_identity(id); 961 idtab->nentries--; 962 } else 963 deadline = (deadline == 0) ? id->death : 964 MINIMUM(deadline, id->death); 965 } 966 if (deadline == 0 || deadline <= now) 967 return 0; 968 else 969 return (deadline - now); 970 } 971 972 static int 973 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 974 { 975 u_char key_is_ca; 976 size_t elen = 0; 977 int r; 978 struct sshkey *k = NULL; 979 char *fp; 980 981 memset(dch, '\0', sizeof(*dch)); 982 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 983 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 984 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 985 error_fr(r, "parse"); 986 goto out; 987 } 988 if (elen != 0) { 989 error_f("unsupported extensions (len %zu)", elen); 990 r = SSH_ERR_FEATURE_UNSUPPORTED; 991 goto out; 992 } 993 if (*dch->hostname == '\0') { 994 free(dch->hostname); 995 dch->hostname = NULL; 996 } 997 if (*dch->user == '\0') { 998 free(dch->user); 999 dch->user = NULL; 1000 } 1001 while (sshbuf_len(b) != 0) { 1002 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1003 dch->nkeys + 1, sizeof(*dch->keys)); 1004 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1005 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1006 if ((r = sshkey_froms(b, &k)) != 0 || 1007 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1008 goto out; 1009 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1010 SSH_FP_DEFAULT)) == NULL) 1011 fatal_f("fingerprint failed"); 1012 debug3_f("%s%s%s: adding %skey %s %s", 1013 dch->user == NULL ? "" : dch->user, 1014 dch->user == NULL ? "" : "@", 1015 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1016 free(fp); 1017 dch->keys[dch->nkeys] = k; 1018 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1019 dch->nkeys++; 1020 k = NULL; /* transferred */ 1021 } 1022 /* success */ 1023 r = 0; 1024 out: 1025 sshkey_free(k); 1026 return r; 1027 } 1028 1029 static int 1030 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1031 { 1032 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1033 int r; 1034 size_t elen = 0; 1035 1036 debug3_f("entering"); 1037 1038 memset(dc, '\0', sizeof(*dc)); 1039 if ((r = sshbuf_froms(m, &b)) != 0 || 1040 (r = sshbuf_froms(b, &frombuf)) != 0 || 1041 (r = sshbuf_froms(b, &tobuf)) != 0 || 1042 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1043 error_fr(r, "parse"); 1044 goto out; 1045 } 1046 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1047 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1048 goto out; /* already logged */ 1049 if (elen != 0) { 1050 error_f("unsupported extensions (len %zu)", elen); 1051 r = SSH_ERR_FEATURE_UNSUPPORTED; 1052 goto out; 1053 } 1054 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1055 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1056 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1057 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1058 /* check consistency */ 1059 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1060 dc->from.user != NULL) { 1061 error_f("inconsistent \"from\" specification"); 1062 r = SSH_ERR_INVALID_FORMAT; 1063 goto out; 1064 } 1065 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1066 error_f("incomplete \"to\" specification"); 1067 r = SSH_ERR_INVALID_FORMAT; 1068 goto out; 1069 } 1070 /* success */ 1071 r = 0; 1072 out: 1073 sshbuf_free(b); 1074 sshbuf_free(frombuf); 1075 sshbuf_free(tobuf); 1076 return r; 1077 } 1078 1079 static int 1080 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1081 struct dest_constraint **dcsp, size_t *ndcsp) 1082 { 1083 char *ext_name = NULL; 1084 int r; 1085 struct sshbuf *b = NULL; 1086 1087 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1088 error_fr(r, "parse constraint extension"); 1089 goto out; 1090 } 1091 debug_f("constraint ext %s", ext_name); 1092 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1093 if (sk_providerp == NULL) { 1094 error_f("%s not valid here", ext_name); 1095 r = SSH_ERR_INVALID_FORMAT; 1096 goto out; 1097 } 1098 if (*sk_providerp != NULL) { 1099 error_f("%s already set", ext_name); 1100 r = SSH_ERR_INVALID_FORMAT; 1101 goto out; 1102 } 1103 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1104 error_fr(r, "parse %s", ext_name); 1105 goto out; 1106 } 1107 } else if (strcmp(ext_name, 1108 "restrict-destination-v00@openssh.com") == 0) { 1109 if (*dcsp != NULL) { 1110 error_f("%s already set", ext_name); 1111 goto out; 1112 } 1113 if ((r = sshbuf_froms(m, &b)) != 0) { 1114 error_fr(r, "parse %s outer", ext_name); 1115 goto out; 1116 } 1117 while (sshbuf_len(b) != 0) { 1118 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1119 error_f("too many %s constraints", ext_name); 1120 goto out; 1121 } 1122 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1123 sizeof(**dcsp)); 1124 if ((r = parse_dest_constraint(b, 1125 *dcsp + (*ndcsp)++)) != 0) 1126 goto out; /* error already logged */ 1127 } 1128 } else { 1129 error_f("unsupported constraint \"%s\"", ext_name); 1130 r = SSH_ERR_FEATURE_UNSUPPORTED; 1131 goto out; 1132 } 1133 /* success */ 1134 r = 0; 1135 out: 1136 free(ext_name); 1137 sshbuf_free(b); 1138 return r; 1139 } 1140 1141 static int 1142 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1143 u_int *secondsp, int *confirmp, char **sk_providerp, 1144 struct dest_constraint **dcsp, size_t *ndcsp) 1145 { 1146 u_char ctype; 1147 int r; 1148 u_int seconds, maxsign = 0; 1149 1150 while (sshbuf_len(m)) { 1151 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1152 error_fr(r, "parse constraint type"); 1153 goto out; 1154 } 1155 switch (ctype) { 1156 case SSH_AGENT_CONSTRAIN_LIFETIME: 1157 if (*deathp != 0) { 1158 error_f("lifetime already set"); 1159 r = SSH_ERR_INVALID_FORMAT; 1160 goto out; 1161 } 1162 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1163 error_fr(r, "parse lifetime constraint"); 1164 goto out; 1165 } 1166 *deathp = monotime() + seconds; 1167 *secondsp = seconds; 1168 break; 1169 case SSH_AGENT_CONSTRAIN_CONFIRM: 1170 if (*confirmp != 0) { 1171 error_f("confirm already set"); 1172 r = SSH_ERR_INVALID_FORMAT; 1173 goto out; 1174 } 1175 *confirmp = 1; 1176 break; 1177 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1178 if (k == NULL) { 1179 error_f("maxsign not valid here"); 1180 r = SSH_ERR_INVALID_FORMAT; 1181 goto out; 1182 } 1183 if (maxsign != 0) { 1184 error_f("maxsign already set"); 1185 r = SSH_ERR_INVALID_FORMAT; 1186 goto out; 1187 } 1188 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1189 error_fr(r, "parse maxsign constraint"); 1190 goto out; 1191 } 1192 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1193 error_fr(r, "enable maxsign"); 1194 goto out; 1195 } 1196 break; 1197 case SSH_AGENT_CONSTRAIN_EXTENSION: 1198 if ((r = parse_key_constraint_extension(m, 1199 sk_providerp, dcsp, ndcsp)) != 0) 1200 goto out; /* error already logged */ 1201 break; 1202 default: 1203 error_f("Unknown constraint %d", ctype); 1204 r = SSH_ERR_FEATURE_UNSUPPORTED; 1205 goto out; 1206 } 1207 } 1208 /* success */ 1209 r = 0; 1210 out: 1211 return r; 1212 } 1213 1214 static void 1215 process_add_identity(SocketEntry *e) 1216 { 1217 Identity *id; 1218 int success = 0, confirm = 0; 1219 char *fp, *comment = NULL, *sk_provider = NULL; 1220 char canonical_provider[PATH_MAX]; 1221 time_t death = 0; 1222 u_int seconds = 0; 1223 struct dest_constraint *dest_constraints = NULL; 1224 size_t ndest_constraints = 0; 1225 struct sshkey *k = NULL; 1226 int r = SSH_ERR_INTERNAL_ERROR; 1227 1228 debug2_f("entering"); 1229 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1230 k == NULL || 1231 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1232 error_fr(r, "parse"); 1233 goto out; 1234 } 1235 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1236 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1237 error_f("failed to parse constraints"); 1238 sshbuf_reset(e->request); 1239 goto out; 1240 } 1241 1242 if (sk_provider != NULL) { 1243 if (!sshkey_is_sk(k)) { 1244 error("Cannot add provider: %s is not an " 1245 "authenticator-hosted key", sshkey_type(k)); 1246 goto out; 1247 } 1248 if (strcasecmp(sk_provider, "internal") == 0) { 1249 debug_f("internal provider"); 1250 } else { 1251 if (realpath(sk_provider, canonical_provider) == NULL) { 1252 verbose("failed provider \"%.100s\": " 1253 "realpath: %s", sk_provider, 1254 strerror(errno)); 1255 goto out; 1256 } 1257 free(sk_provider); 1258 sk_provider = xstrdup(canonical_provider); 1259 if (match_pattern_list(sk_provider, 1260 allowed_providers, 0) != 1) { 1261 error("Refusing add key: " 1262 "provider %s not allowed", sk_provider); 1263 goto out; 1264 } 1265 } 1266 } 1267 if ((r = sshkey_shield_private(k)) != 0) { 1268 error_fr(r, "shield private"); 1269 goto out; 1270 } 1271 if (lifetime && !death) 1272 death = monotime() + lifetime; 1273 if ((id = lookup_identity(k)) == NULL) { 1274 id = xcalloc(1, sizeof(Identity)); 1275 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1276 /* Increment the number of identities. */ 1277 idtab->nentries++; 1278 } else { 1279 /* identity not visible, do not update */ 1280 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1281 goto out; /* error already logged */ 1282 /* key state might have been updated */ 1283 sshkey_free(id->key); 1284 free(id->comment); 1285 free(id->sk_provider); 1286 free_dest_constraints(id->dest_constraints, 1287 id->ndest_constraints); 1288 } 1289 /* success */ 1290 id->key = k; 1291 id->comment = comment; 1292 id->death = death; 1293 id->confirm = confirm; 1294 id->sk_provider = sk_provider; 1295 id->dest_constraints = dest_constraints; 1296 id->ndest_constraints = ndest_constraints; 1297 1298 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1299 SSH_FP_DEFAULT)) == NULL) 1300 fatal_f("sshkey_fingerprint failed"); 1301 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1302 "(provider: %s) (destination constraints: %zu)", 1303 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1304 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1305 free(fp); 1306 /* transferred */ 1307 k = NULL; 1308 comment = NULL; 1309 sk_provider = NULL; 1310 dest_constraints = NULL; 1311 ndest_constraints = 0; 1312 success = 1; 1313 out: 1314 free(sk_provider); 1315 free(comment); 1316 sshkey_free(k); 1317 free_dest_constraints(dest_constraints, ndest_constraints); 1318 send_status(e, success); 1319 } 1320 1321 /* XXX todo: encrypt sensitive data with passphrase */ 1322 static void 1323 process_lock_agent(SocketEntry *e, int lock) 1324 { 1325 int r, success = 0, delay; 1326 char *passwd; 1327 u_char passwdhash[LOCK_SIZE]; 1328 static u_int fail_count = 0; 1329 size_t pwlen; 1330 1331 debug2_f("entering"); 1332 /* 1333 * This is deliberately fatal: the user has requested that we lock, 1334 * but we can't parse their request properly. The only safe thing to 1335 * do is abort. 1336 */ 1337 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1338 fatal_fr(r, "parse"); 1339 if (pwlen == 0) { 1340 debug("empty password not supported"); 1341 } else if (locked && !lock) { 1342 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1343 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1344 fatal("bcrypt_pbkdf"); 1345 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1346 debug("agent unlocked"); 1347 locked = 0; 1348 fail_count = 0; 1349 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1350 success = 1; 1351 } else { 1352 /* delay in 0.1s increments up to 10s */ 1353 if (fail_count < 100) 1354 fail_count++; 1355 delay = 100000 * fail_count; 1356 debug("unlock failed, delaying %0.1lf seconds", 1357 (double)delay/1000000); 1358 usleep(delay); 1359 } 1360 explicit_bzero(passwdhash, sizeof(passwdhash)); 1361 } else if (!locked && lock) { 1362 debug("agent locked"); 1363 locked = 1; 1364 arc4random_buf(lock_salt, sizeof(lock_salt)); 1365 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1366 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1367 fatal("bcrypt_pbkdf"); 1368 success = 1; 1369 } 1370 freezero(passwd, pwlen); 1371 send_status(e, success); 1372 } 1373 1374 static void 1375 no_identities(SocketEntry *e) 1376 { 1377 struct sshbuf *msg; 1378 int r; 1379 1380 if ((msg = sshbuf_new()) == NULL) 1381 fatal_f("sshbuf_new failed"); 1382 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1383 (r = sshbuf_put_u32(msg, 0)) != 0 || 1384 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1385 fatal_fr(r, "compose"); 1386 sshbuf_free(msg); 1387 } 1388 1389 #ifdef ENABLE_PKCS11 1390 static void 1391 process_add_smartcard_key(SocketEntry *e) 1392 { 1393 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1394 char **comments = NULL; 1395 int r, i, count = 0, success = 0, confirm = 0; 1396 u_int seconds = 0; 1397 time_t death = 0; 1398 struct sshkey **keys = NULL, *k; 1399 Identity *id; 1400 struct dest_constraint *dest_constraints = NULL; 1401 size_t ndest_constraints = 0; 1402 1403 debug2_f("entering"); 1404 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1405 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1406 error_fr(r, "parse"); 1407 goto send; 1408 } 1409 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1410 NULL, &dest_constraints, &ndest_constraints) != 0) { 1411 error_f("failed to parse constraints"); 1412 goto send; 1413 } 1414 if (realpath(provider, canonical_provider) == NULL) { 1415 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1416 provider, strerror(errno)); 1417 goto send; 1418 } 1419 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1420 verbose("refusing PKCS#11 add of \"%.100s\": " 1421 "provider not allowed", canonical_provider); 1422 goto send; 1423 } 1424 debug_f("add %.100s", canonical_provider); 1425 if (lifetime && !death) 1426 death = monotime() + lifetime; 1427 1428 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1429 for (i = 0; i < count; i++) { 1430 k = keys[i]; 1431 if (lookup_identity(k) == NULL) { 1432 id = xcalloc(1, sizeof(Identity)); 1433 id->key = k; 1434 keys[i] = NULL; /* transferred */ 1435 id->provider = xstrdup(canonical_provider); 1436 if (*comments[i] != '\0') { 1437 id->comment = comments[i]; 1438 comments[i] = NULL; /* transferred */ 1439 } else { 1440 id->comment = xstrdup(canonical_provider); 1441 } 1442 id->death = death; 1443 id->confirm = confirm; 1444 id->dest_constraints = dest_constraints; 1445 id->ndest_constraints = ndest_constraints; 1446 dest_constraints = NULL; /* transferred */ 1447 ndest_constraints = 0; 1448 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1449 idtab->nentries++; 1450 success = 1; 1451 } 1452 /* XXX update constraints for existing keys */ 1453 sshkey_free(keys[i]); 1454 free(comments[i]); 1455 } 1456 send: 1457 free(pin); 1458 free(provider); 1459 free(keys); 1460 free(comments); 1461 free_dest_constraints(dest_constraints, ndest_constraints); 1462 send_status(e, success); 1463 } 1464 1465 static void 1466 process_remove_smartcard_key(SocketEntry *e) 1467 { 1468 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1469 int r, success = 0; 1470 Identity *id, *nxt; 1471 1472 debug2_f("entering"); 1473 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1474 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1475 error_fr(r, "parse"); 1476 goto send; 1477 } 1478 free(pin); 1479 1480 if (realpath(provider, canonical_provider) == NULL) { 1481 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1482 provider, strerror(errno)); 1483 goto send; 1484 } 1485 1486 debug_f("remove %.100s", canonical_provider); 1487 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1488 nxt = TAILQ_NEXT(id, next); 1489 /* Skip file--based keys */ 1490 if (id->provider == NULL) 1491 continue; 1492 if (!strcmp(canonical_provider, id->provider)) { 1493 TAILQ_REMOVE(&idtab->idlist, id, next); 1494 free_identity(id); 1495 idtab->nentries--; 1496 } 1497 } 1498 if (pkcs11_del_provider(canonical_provider) == 0) 1499 success = 1; 1500 else 1501 error_f("pkcs11_del_provider failed"); 1502 send: 1503 free(provider); 1504 send_status(e, success); 1505 } 1506 #endif /* ENABLE_PKCS11 */ 1507 1508 static int 1509 process_ext_session_bind(SocketEntry *e) 1510 { 1511 int r, sid_match, key_match; 1512 struct sshkey *key = NULL; 1513 struct sshbuf *sid = NULL, *sig = NULL; 1514 char *fp = NULL; 1515 size_t i; 1516 u_char fwd = 0; 1517 1518 debug2_f("entering"); 1519 if ((r = sshkey_froms(e->request, &key)) != 0 || 1520 (r = sshbuf_froms(e->request, &sid)) != 0 || 1521 (r = sshbuf_froms(e->request, &sig)) != 0 || 1522 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1523 error_fr(r, "parse"); 1524 goto out; 1525 } 1526 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1527 SSH_FP_DEFAULT)) == NULL) 1528 fatal_f("fingerprint failed"); 1529 /* check signature with hostkey on session ID */ 1530 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1531 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1532 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1533 goto out; 1534 } 1535 /* check whether sid/key already recorded */ 1536 for (i = 0; i < e->nsession_ids; i++) { 1537 if (!e->session_ids[i].forwarded) { 1538 error_f("attempt to bind session ID to socket " 1539 "previously bound for authentication attempt"); 1540 r = -1; 1541 goto out; 1542 } 1543 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1544 key_match = sshkey_equal(key, e->session_ids[i].key); 1545 if (sid_match && key_match) { 1546 debug_f("session ID already recorded for %s %s", 1547 sshkey_type(key), fp); 1548 r = 0; 1549 goto out; 1550 } else if (sid_match) { 1551 error_f("session ID recorded against different key " 1552 "for %s %s", sshkey_type(key), fp); 1553 r = -1; 1554 goto out; 1555 } 1556 /* 1557 * new sid with previously-seen key can happen, e.g. multiple 1558 * connections to the same host. 1559 */ 1560 } 1561 /* record new key/sid */ 1562 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1563 error_f("too many session IDs recorded"); 1564 goto out; 1565 } 1566 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1567 e->nsession_ids + 1, sizeof(*e->session_ids)); 1568 i = e->nsession_ids++; 1569 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1570 AGENT_MAX_SESSION_IDS); 1571 e->session_ids[i].key = key; 1572 e->session_ids[i].forwarded = fwd != 0; 1573 key = NULL; /* transferred */ 1574 /* can't transfer sid; it's refcounted and scoped to request's life */ 1575 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1576 fatal_f("sshbuf_new"); 1577 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1578 fatal_fr(r, "sshbuf_putb session ID"); 1579 /* success */ 1580 r = 0; 1581 out: 1582 free(fp); 1583 sshkey_free(key); 1584 sshbuf_free(sid); 1585 sshbuf_free(sig); 1586 return r == 0 ? 1 : 0; 1587 } 1588 1589 static void 1590 process_extension(SocketEntry *e) 1591 { 1592 int r, success = 0; 1593 char *name; 1594 1595 debug2_f("entering"); 1596 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1597 error_fr(r, "parse"); 1598 goto send; 1599 } 1600 if (strcmp(name, "session-bind@openssh.com") == 0) 1601 success = process_ext_session_bind(e); 1602 else 1603 debug_f("unsupported extension \"%s\"", name); 1604 free(name); 1605 send: 1606 send_status(e, success); 1607 } 1608 /* 1609 * dispatch incoming message. 1610 * returns 1 on success, 0 for incomplete messages or -1 on error. 1611 */ 1612 static int 1613 process_message(u_int socknum) 1614 { 1615 u_int msg_len; 1616 u_char type; 1617 const u_char *cp; 1618 int r; 1619 SocketEntry *e; 1620 1621 if (socknum >= sockets_alloc) 1622 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1623 e = &sockets[socknum]; 1624 1625 if (sshbuf_len(e->input) < 5) 1626 return 0; /* Incomplete message header. */ 1627 cp = sshbuf_ptr(e->input); 1628 msg_len = PEEK_U32(cp); 1629 if (msg_len > AGENT_MAX_LEN) { 1630 debug_f("socket %u (fd=%d) message too long %u > %u", 1631 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1632 return -1; 1633 } 1634 if (sshbuf_len(e->input) < msg_len + 4) 1635 return 0; /* Incomplete message body. */ 1636 1637 /* move the current input to e->request */ 1638 sshbuf_reset(e->request); 1639 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1640 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1641 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1642 r == SSH_ERR_STRING_TOO_LARGE) { 1643 error_fr(r, "parse"); 1644 return -1; 1645 } 1646 fatal_fr(r, "parse"); 1647 } 1648 1649 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1650 1651 /* check whether agent is locked */ 1652 if (locked && type != SSH_AGENTC_UNLOCK) { 1653 sshbuf_reset(e->request); 1654 switch (type) { 1655 case SSH2_AGENTC_REQUEST_IDENTITIES: 1656 /* send empty lists */ 1657 no_identities(e); 1658 break; 1659 default: 1660 /* send a fail message for all other request types */ 1661 send_status(e, 0); 1662 } 1663 return 1; 1664 } 1665 1666 switch (type) { 1667 case SSH_AGENTC_LOCK: 1668 case SSH_AGENTC_UNLOCK: 1669 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1670 break; 1671 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1672 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1673 break; 1674 /* ssh2 */ 1675 case SSH2_AGENTC_SIGN_REQUEST: 1676 process_sign_request2(e); 1677 break; 1678 case SSH2_AGENTC_REQUEST_IDENTITIES: 1679 process_request_identities(e); 1680 break; 1681 case SSH2_AGENTC_ADD_IDENTITY: 1682 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1683 process_add_identity(e); 1684 break; 1685 case SSH2_AGENTC_REMOVE_IDENTITY: 1686 process_remove_identity(e); 1687 break; 1688 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1689 process_remove_all_identities(e); 1690 break; 1691 #ifdef ENABLE_PKCS11 1692 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1693 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1694 process_add_smartcard_key(e); 1695 break; 1696 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1697 process_remove_smartcard_key(e); 1698 break; 1699 #endif /* ENABLE_PKCS11 */ 1700 case SSH_AGENTC_EXTENSION: 1701 process_extension(e); 1702 break; 1703 default: 1704 /* Unknown message. Respond with failure. */ 1705 error("Unknown message %d", type); 1706 sshbuf_reset(e->request); 1707 send_status(e, 0); 1708 break; 1709 } 1710 return 1; 1711 } 1712 1713 static void 1714 new_socket(sock_type type, int fd) 1715 { 1716 u_int i, old_alloc, new_alloc; 1717 1718 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1719 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1720 if (type == AUTH_CONNECTION) { 1721 debug("xcount %d -> %d", xcount, xcount + 1); 1722 ++xcount; 1723 } 1724 set_nonblock(fd); 1725 1726 if (fd > max_fd) 1727 max_fd = fd; 1728 1729 for (i = 0; i < sockets_alloc; i++) 1730 if (sockets[i].type == AUTH_UNUSED) { 1731 sockets[i].fd = fd; 1732 if ((sockets[i].input = sshbuf_new()) == NULL || 1733 (sockets[i].output = sshbuf_new()) == NULL || 1734 (sockets[i].request = sshbuf_new()) == NULL) 1735 fatal_f("sshbuf_new failed"); 1736 sockets[i].type = type; 1737 return; 1738 } 1739 old_alloc = sockets_alloc; 1740 new_alloc = sockets_alloc + 10; 1741 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1742 sizeof(sockets[0])); 1743 for (i = old_alloc; i < new_alloc; i++) 1744 sockets[i].type = AUTH_UNUSED; 1745 sockets_alloc = new_alloc; 1746 sockets[old_alloc].fd = fd; 1747 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1748 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1749 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1750 fatal_f("sshbuf_new failed"); 1751 sockets[old_alloc].type = type; 1752 } 1753 1754 static int 1755 handle_socket_read(u_int socknum) 1756 { 1757 struct sockaddr_un sunaddr; 1758 socklen_t slen; 1759 uid_t euid; 1760 gid_t egid; 1761 int fd; 1762 1763 slen = sizeof(sunaddr); 1764 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1765 if (fd == -1) { 1766 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1767 return -1; 1768 } 1769 if (getpeereid(fd, &euid, &egid) == -1) { 1770 error("getpeereid %d failed: %s", fd, strerror(errno)); 1771 close(fd); 1772 return -1; 1773 } 1774 if ((euid != 0) && (getuid() != euid)) { 1775 error("uid mismatch: peer euid %u != uid %u", 1776 (u_int) euid, (u_int) getuid()); 1777 close(fd); 1778 return -1; 1779 } 1780 new_socket(AUTH_CONNECTION, fd); 1781 return 0; 1782 } 1783 1784 static int 1785 handle_conn_read(u_int socknum) 1786 { 1787 char buf[AGENT_RBUF_LEN]; 1788 ssize_t len; 1789 int r; 1790 1791 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1792 if (len == -1) { 1793 if (errno == EAGAIN || errno == EINTR) 1794 return 0; 1795 error_f("read error on socket %u (fd %d): %s", 1796 socknum, sockets[socknum].fd, strerror(errno)); 1797 } 1798 return -1; 1799 } 1800 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1801 fatal_fr(r, "compose"); 1802 explicit_bzero(buf, sizeof(buf)); 1803 for (;;) { 1804 if ((r = process_message(socknum)) == -1) 1805 return -1; 1806 else if (r == 0) 1807 break; 1808 } 1809 return 0; 1810 } 1811 1812 static int 1813 handle_conn_write(u_int socknum) 1814 { 1815 ssize_t len; 1816 int r; 1817 1818 if (sshbuf_len(sockets[socknum].output) == 0) 1819 return 0; /* shouldn't happen */ 1820 if ((len = write(sockets[socknum].fd, 1821 sshbuf_ptr(sockets[socknum].output), 1822 sshbuf_len(sockets[socknum].output))) <= 0) { 1823 if (len == -1) { 1824 if (errno == EAGAIN || errno == EINTR) 1825 return 0; 1826 error_f("read error on socket %u (fd %d): %s", 1827 socknum, sockets[socknum].fd, strerror(errno)); 1828 } 1829 return -1; 1830 } 1831 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1832 fatal_fr(r, "consume"); 1833 return 0; 1834 } 1835 1836 static void 1837 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1838 { 1839 size_t i; 1840 u_int socknum, activefds = npfd; 1841 1842 for (i = 0; i < npfd; i++) { 1843 if (pfd[i].revents == 0) 1844 continue; 1845 /* Find sockets entry */ 1846 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1847 if (sockets[socknum].type != AUTH_SOCKET && 1848 sockets[socknum].type != AUTH_CONNECTION) 1849 continue; 1850 if (pfd[i].fd == sockets[socknum].fd) 1851 break; 1852 } 1853 if (socknum >= sockets_alloc) { 1854 error_f("no socket for fd %d", pfd[i].fd); 1855 continue; 1856 } 1857 /* Process events */ 1858 switch (sockets[socknum].type) { 1859 case AUTH_SOCKET: 1860 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1861 break; 1862 if (npfd > maxfds) { 1863 debug3("out of fds (active %u >= limit %u); " 1864 "skipping accept", activefds, maxfds); 1865 break; 1866 } 1867 if (handle_socket_read(socknum) == 0) 1868 activefds++; 1869 break; 1870 case AUTH_CONNECTION: 1871 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1872 handle_conn_read(socknum) != 0) 1873 goto close_sock; 1874 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1875 handle_conn_write(socknum) != 0) { 1876 close_sock: 1877 if (activefds == 0) 1878 fatal("activefds == 0 at close_sock"); 1879 close_socket(&sockets[socknum]); 1880 activefds--; 1881 break; 1882 } 1883 break; 1884 default: 1885 break; 1886 } 1887 } 1888 } 1889 1890 static int 1891 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1892 { 1893 struct pollfd *pfd = *pfdp; 1894 size_t i, j, npfd = 0; 1895 time_t deadline; 1896 int r; 1897 1898 /* Count active sockets */ 1899 for (i = 0; i < sockets_alloc; i++) { 1900 switch (sockets[i].type) { 1901 case AUTH_SOCKET: 1902 case AUTH_CONNECTION: 1903 npfd++; 1904 break; 1905 case AUTH_UNUSED: 1906 break; 1907 default: 1908 fatal("Unknown socket type %d", sockets[i].type); 1909 break; 1910 } 1911 } 1912 if (npfd != *npfdp && 1913 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1914 fatal_f("recallocarray failed"); 1915 *pfdp = pfd; 1916 *npfdp = npfd; 1917 1918 for (i = j = 0; i < sockets_alloc; i++) { 1919 switch (sockets[i].type) { 1920 case AUTH_SOCKET: 1921 if (npfd > maxfds) { 1922 debug3("out of fds (active %zu >= limit %u); " 1923 "skipping arming listener", npfd, maxfds); 1924 break; 1925 } 1926 pfd[j].fd = sockets[i].fd; 1927 pfd[j].revents = 0; 1928 pfd[j].events = POLLIN; 1929 j++; 1930 break; 1931 case AUTH_CONNECTION: 1932 pfd[j].fd = sockets[i].fd; 1933 pfd[j].revents = 0; 1934 /* 1935 * Only prepare to read if we can handle a full-size 1936 * input read buffer and enqueue a max size reply.. 1937 */ 1938 if ((r = sshbuf_check_reserve(sockets[i].input, 1939 AGENT_RBUF_LEN)) == 0 && 1940 (r = sshbuf_check_reserve(sockets[i].output, 1941 AGENT_MAX_LEN)) == 0) 1942 pfd[j].events = POLLIN; 1943 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1944 fatal_fr(r, "reserve"); 1945 if (sshbuf_len(sockets[i].output) > 0) 1946 pfd[j].events |= POLLOUT; 1947 j++; 1948 break; 1949 default: 1950 break; 1951 } 1952 } 1953 deadline = reaper(); 1954 if (parent_alive_interval != 0) 1955 deadline = (deadline == 0) ? parent_alive_interval : 1956 MINIMUM(deadline, parent_alive_interval); 1957 if (deadline == 0) { 1958 *timeoutp = -1; /* INFTIM */ 1959 } else { 1960 if (deadline > INT_MAX / 1000) 1961 *timeoutp = INT_MAX / 1000; 1962 else 1963 *timeoutp = deadline * 1000; 1964 } 1965 return (1); 1966 } 1967 1968 static void 1969 cleanup_socket(void) 1970 { 1971 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1972 return; 1973 debug_f("cleanup"); 1974 if (socket_name[0]) 1975 unlink(socket_name); 1976 if (socket_dir[0]) 1977 rmdir(socket_dir); 1978 } 1979 1980 void 1981 cleanup_exit(int i) 1982 { 1983 cleanup_socket(); 1984 _exit(i); 1985 } 1986 1987 /*ARGSUSED*/ 1988 static void 1989 cleanup_handler(int sig) 1990 { 1991 cleanup_socket(); 1992 #ifdef ENABLE_PKCS11 1993 pkcs11_terminate(); 1994 #endif 1995 _exit(2); 1996 } 1997 1998 static void 1999 check_parent_exists(void) 2000 { 2001 /* 2002 * If our parent has exited then getppid() will return (pid_t)1, 2003 * so testing for that should be safe. 2004 */ 2005 if (parent_pid != -1 && getppid() != parent_pid) { 2006 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2007 cleanup_socket(); 2008 _exit(2); 2009 } 2010 } 2011 2012 static void 2013 usage(void) 2014 { 2015 fprintf(stderr, 2016 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2017 " [-P allowed_providers] [-t life]\n" 2018 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 2019 " [-t life] command [arg ...]\n" 2020 " ssh-agent [-c | -s] -k\n"); 2021 exit(1); 2022 } 2023 2024 int 2025 main(int ac, char **av) 2026 { 2027 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2028 int sock, ch, result, saved_errno; 2029 char *shell, *format, *pidstr, *agentsocket = NULL; 2030 #ifdef HAVE_SETRLIMIT 2031 struct rlimit rlim; 2032 #endif 2033 extern int optind; 2034 extern char *optarg; 2035 pid_t pid; 2036 char pidstrbuf[1 + 3 * sizeof pid]; 2037 size_t len; 2038 mode_t prev_mask; 2039 int timeout = -1; /* INFTIM */ 2040 struct pollfd *pfd = NULL; 2041 size_t npfd = 0; 2042 u_int maxfds; 2043 2044 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2045 sanitise_stdfd(); 2046 2047 /* drop */ 2048 setegid(getgid()); 2049 setgid(getgid()); 2050 setuid(geteuid()); 2051 2052 platform_disable_tracing(0); /* strict=no */ 2053 2054 #ifdef RLIMIT_NOFILE 2055 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2056 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2057 #endif 2058 2059 __progname = ssh_get_progname(av[0]); 2060 seed_rng(); 2061 2062 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2063 switch (ch) { 2064 case 'E': 2065 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2066 if (fingerprint_hash == -1) 2067 fatal("Invalid hash algorithm \"%s\"", optarg); 2068 break; 2069 case 'c': 2070 if (s_flag) 2071 usage(); 2072 c_flag++; 2073 break; 2074 case 'k': 2075 k_flag++; 2076 break; 2077 case 'O': 2078 if (strcmp(optarg, "no-restrict-websafe") == 0) 2079 restrict_websafe = 0; 2080 else 2081 fatal("Unknown -O option"); 2082 break; 2083 case 'P': 2084 if (allowed_providers != NULL) 2085 fatal("-P option already specified"); 2086 allowed_providers = xstrdup(optarg); 2087 break; 2088 case 's': 2089 if (c_flag) 2090 usage(); 2091 s_flag++; 2092 break; 2093 case 'd': 2094 if (d_flag || D_flag) 2095 usage(); 2096 d_flag++; 2097 break; 2098 case 'D': 2099 if (d_flag || D_flag) 2100 usage(); 2101 D_flag++; 2102 break; 2103 case 'a': 2104 agentsocket = optarg; 2105 break; 2106 case 't': 2107 if ((lifetime = convtime(optarg)) == -1) { 2108 fprintf(stderr, "Invalid lifetime\n"); 2109 usage(); 2110 } 2111 break; 2112 case 'x': 2113 xcount = 0; 2114 break; 2115 default: 2116 usage(); 2117 } 2118 } 2119 ac -= optind; 2120 av += optind; 2121 2122 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2123 usage(); 2124 2125 if (allowed_providers == NULL) 2126 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2127 2128 if (ac == 0 && !c_flag && !s_flag) { 2129 shell = getenv("SHELL"); 2130 if (shell != NULL && (len = strlen(shell)) > 2 && 2131 strncmp(shell + len - 3, "csh", 3) == 0) 2132 c_flag = 1; 2133 } 2134 if (k_flag) { 2135 const char *errstr = NULL; 2136 2137 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2138 if (pidstr == NULL) { 2139 fprintf(stderr, "%s not set, cannot kill agent\n", 2140 SSH_AGENTPID_ENV_NAME); 2141 exit(1); 2142 } 2143 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2144 if (errstr) { 2145 fprintf(stderr, 2146 "%s=\"%s\", which is not a good PID: %s\n", 2147 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2148 exit(1); 2149 } 2150 if (kill(pid, SIGTERM) == -1) { 2151 perror("kill"); 2152 exit(1); 2153 } 2154 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2155 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2156 printf(format, SSH_AGENTPID_ENV_NAME); 2157 printf("echo Agent pid %ld killed;\n", (long)pid); 2158 exit(0); 2159 } 2160 2161 /* 2162 * Minimum file descriptors: 2163 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2164 * a few spare for libc / stack protectors / sanitisers, etc. 2165 */ 2166 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2167 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2168 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2169 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2170 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2171 2172 parent_pid = getpid(); 2173 2174 if (agentsocket == NULL) { 2175 /* Create private directory for agent socket */ 2176 mktemp_proto(socket_dir, sizeof(socket_dir)); 2177 if (mkdtemp(socket_dir) == NULL) { 2178 perror("mkdtemp: private socket dir"); 2179 exit(1); 2180 } 2181 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2182 (long)parent_pid); 2183 } else { 2184 /* Try to use specified agent socket */ 2185 socket_dir[0] = '\0'; 2186 strlcpy(socket_name, agentsocket, sizeof socket_name); 2187 } 2188 2189 /* 2190 * Create socket early so it will exist before command gets run from 2191 * the parent. 2192 */ 2193 prev_mask = umask(0177); 2194 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2195 if (sock < 0) { 2196 /* XXX - unix_listener() calls error() not perror() */ 2197 *socket_name = '\0'; /* Don't unlink any existing file */ 2198 cleanup_exit(1); 2199 } 2200 umask(prev_mask); 2201 2202 /* 2203 * Fork, and have the parent execute the command, if any, or present 2204 * the socket data. The child continues as the authentication agent. 2205 */ 2206 if (D_flag || d_flag) { 2207 log_init(__progname, 2208 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2209 SYSLOG_FACILITY_AUTH, 1); 2210 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2211 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2212 SSH_AUTHSOCKET_ENV_NAME); 2213 printf("echo Agent pid %ld;\n", (long)parent_pid); 2214 fflush(stdout); 2215 goto skip; 2216 } 2217 pid = fork(); 2218 if (pid == -1) { 2219 perror("fork"); 2220 cleanup_exit(1); 2221 } 2222 if (pid != 0) { /* Parent - execute the given command. */ 2223 close(sock); 2224 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2225 if (ac == 0) { 2226 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2227 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2228 SSH_AUTHSOCKET_ENV_NAME); 2229 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2230 SSH_AGENTPID_ENV_NAME); 2231 printf("echo Agent pid %ld;\n", (long)pid); 2232 exit(0); 2233 } 2234 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2235 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2236 perror("setenv"); 2237 exit(1); 2238 } 2239 execvp(av[0], av); 2240 perror(av[0]); 2241 exit(1); 2242 } 2243 /* child */ 2244 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2245 2246 if (setsid() == -1) { 2247 error("setsid: %s", strerror(errno)); 2248 cleanup_exit(1); 2249 } 2250 2251 (void)chdir("/"); 2252 if (stdfd_devnull(1, 1, 1) == -1) 2253 error_f("stdfd_devnull failed"); 2254 2255 #ifdef HAVE_SETRLIMIT 2256 /* deny core dumps, since memory contains unencrypted private keys */ 2257 rlim.rlim_cur = rlim.rlim_max = 0; 2258 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2259 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2260 cleanup_exit(1); 2261 } 2262 #endif 2263 2264 skip: 2265 2266 cleanup_pid = getpid(); 2267 2268 #ifdef ENABLE_PKCS11 2269 pkcs11_init(0); 2270 #endif 2271 new_socket(AUTH_SOCKET, sock); 2272 if (ac > 0) 2273 parent_alive_interval = 10; 2274 idtab_init(); 2275 ssh_signal(SIGPIPE, SIG_IGN); 2276 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2277 ssh_signal(SIGHUP, cleanup_handler); 2278 ssh_signal(SIGTERM, cleanup_handler); 2279 2280 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2281 fatal("%s: pledge: %s", __progname, strerror(errno)); 2282 platform_pledge_agent(); 2283 2284 while (1) { 2285 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2286 result = poll(pfd, npfd, timeout); 2287 saved_errno = errno; 2288 if (parent_alive_interval != 0) 2289 check_parent_exists(); 2290 (void) reaper(); /* remove expired keys */ 2291 if (result == -1) { 2292 if (saved_errno == EINTR) 2293 continue; 2294 fatal("poll: %s", strerror(saved_errno)); 2295 } else if (result > 0) 2296 after_poll(pfd, npfd, maxfds); 2297 } 2298 /* NOTREACHED */ 2299 } 2300