1 /* $OpenBSD: ssh-agent.c,v 1.287 2022/01/14 03:43:48 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 (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 830 !check_websafe_message_contents(key, data)) { 831 /* error already logged */ 832 goto send; 833 } 834 if ((id->key->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) { 835 /* XXX include sig_dest */ 836 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 837 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 838 " and confirm user presence " : " ", 839 sshkey_type(id->key), fp); 840 pin = read_passphrase(prompt, RP_USE_ASKPASS); 841 free(prompt); 842 prompt = NULL; 843 } else if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 844 notifier = notify_start(0, 845 "Confirm user presence for key %s %s%s%s", 846 sshkey_type(id->key), fp, 847 sig_dest == NULL ? "" : "\n", 848 sig_dest == NULL ? "" : sig_dest); 849 } 850 } 851 retry_pin: 852 if ((r = sshkey_sign(id->key, &signature, &slen, 853 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 854 id->sk_provider, pin, compat)) != 0) { 855 debug_fr(r, "sshkey_sign"); 856 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 857 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 858 if (notifier) { 859 notify_complete(notifier, NULL); 860 notifier = NULL; 861 } 862 /* XXX include sig_dest */ 863 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 864 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 865 " and confirm user presence " : " ", 866 sshkey_type(id->key), fp); 867 pin = read_passphrase(prompt, RP_USE_ASKPASS); 868 retried = 1; 869 goto retry_pin; 870 } 871 error_fr(r, "sshkey_sign"); 872 goto send; 873 } 874 /* Success */ 875 ok = 0; 876 send: 877 notify_complete(notifier, "User presence confirmed"); 878 879 if (ok == 0) { 880 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 881 (r = sshbuf_put_string(msg, signature, slen)) != 0) 882 fatal_fr(r, "compose"); 883 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 884 fatal_fr(r, "compose failure"); 885 886 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 887 fatal_fr(r, "enqueue"); 888 889 sshbuf_free(sid); 890 sshbuf_free(data); 891 sshbuf_free(msg); 892 sshkey_free(key); 893 sshkey_free(hostkey); 894 free(fp); 895 free(signature); 896 free(sig_dest); 897 free(user); 898 free(prompt); 899 if (pin != NULL) 900 freezero(pin, strlen(pin)); 901 } 902 903 /* shared */ 904 static void 905 process_remove_identity(SocketEntry *e) 906 { 907 int r, success = 0; 908 struct sshkey *key = NULL; 909 Identity *id; 910 911 debug2_f("entering"); 912 if ((r = sshkey_froms(e->request, &key)) != 0) { 913 error_fr(r, "parse key"); 914 goto done; 915 } 916 if ((id = lookup_identity(key)) == NULL) { 917 debug_f("key not found"); 918 goto done; 919 } 920 /* identity not visible, cannot be removed */ 921 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 922 goto done; /* error already logged */ 923 /* We have this key, free it. */ 924 if (idtab->nentries < 1) 925 fatal_f("internal error: nentries %d", idtab->nentries); 926 TAILQ_REMOVE(&idtab->idlist, id, next); 927 free_identity(id); 928 idtab->nentries--; 929 success = 1; 930 done: 931 sshkey_free(key); 932 send_status(e, success); 933 } 934 935 static void 936 process_remove_all_identities(SocketEntry *e) 937 { 938 Identity *id; 939 940 debug2_f("entering"); 941 /* Loop over all identities and clear the keys. */ 942 for (id = TAILQ_FIRST(&idtab->idlist); id; 943 id = TAILQ_FIRST(&idtab->idlist)) { 944 TAILQ_REMOVE(&idtab->idlist, id, next); 945 free_identity(id); 946 } 947 948 /* Mark that there are no identities. */ 949 idtab->nentries = 0; 950 951 /* Send success. */ 952 send_status(e, 1); 953 } 954 955 /* removes expired keys and returns number of seconds until the next expiry */ 956 static time_t 957 reaper(void) 958 { 959 time_t deadline = 0, now = monotime(); 960 Identity *id, *nxt; 961 962 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 963 nxt = TAILQ_NEXT(id, next); 964 if (id->death == 0) 965 continue; 966 if (now >= id->death) { 967 debug("expiring key '%s'", id->comment); 968 TAILQ_REMOVE(&idtab->idlist, id, next); 969 free_identity(id); 970 idtab->nentries--; 971 } else 972 deadline = (deadline == 0) ? id->death : 973 MINIMUM(deadline, id->death); 974 } 975 if (deadline == 0 || deadline <= now) 976 return 0; 977 else 978 return (deadline - now); 979 } 980 981 static int 982 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 983 { 984 u_char key_is_ca; 985 size_t elen = 0; 986 int r; 987 struct sshkey *k = NULL; 988 char *fp; 989 990 memset(dch, '\0', sizeof(*dch)); 991 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 992 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 993 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 994 error_fr(r, "parse"); 995 goto out; 996 } 997 if (elen != 0) { 998 error_f("unsupported extensions (len %zu)", elen); 999 r = SSH_ERR_FEATURE_UNSUPPORTED; 1000 goto out; 1001 } 1002 if (*dch->hostname == '\0') { 1003 free(dch->hostname); 1004 dch->hostname = NULL; 1005 } 1006 if (*dch->user == '\0') { 1007 free(dch->user); 1008 dch->user = NULL; 1009 } 1010 while (sshbuf_len(b) != 0) { 1011 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1012 dch->nkeys + 1, sizeof(*dch->keys)); 1013 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1014 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1015 if ((r = sshkey_froms(b, &k)) != 0 || 1016 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1017 goto out; 1018 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1019 SSH_FP_DEFAULT)) == NULL) 1020 fatal_f("fingerprint failed"); 1021 debug3_f("%s%s%s: adding %skey %s %s", 1022 dch->user == NULL ? "" : dch->user, 1023 dch->user == NULL ? "" : "@", 1024 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1025 free(fp); 1026 dch->keys[dch->nkeys] = k; 1027 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1028 dch->nkeys++; 1029 k = NULL; /* transferred */ 1030 } 1031 /* success */ 1032 r = 0; 1033 out: 1034 sshkey_free(k); 1035 return r; 1036 } 1037 1038 static int 1039 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1040 { 1041 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1042 int r; 1043 size_t elen = 0; 1044 1045 debug3_f("entering"); 1046 1047 memset(dc, '\0', sizeof(*dc)); 1048 if ((r = sshbuf_froms(m, &b)) != 0 || 1049 (r = sshbuf_froms(b, &frombuf)) != 0 || 1050 (r = sshbuf_froms(b, &tobuf)) != 0 || 1051 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1052 error_fr(r, "parse"); 1053 goto out; 1054 } 1055 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1056 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1057 goto out; /* already logged */ 1058 if (elen != 0) { 1059 error_f("unsupported extensions (len %zu)", elen); 1060 r = SSH_ERR_FEATURE_UNSUPPORTED; 1061 goto out; 1062 } 1063 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1064 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1065 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1066 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1067 /* check consistency */ 1068 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1069 dc->from.user != NULL) { 1070 error_f("inconsistent \"from\" specification"); 1071 r = SSH_ERR_INVALID_FORMAT; 1072 goto out; 1073 } 1074 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1075 error_f("incomplete \"to\" specification"); 1076 r = SSH_ERR_INVALID_FORMAT; 1077 goto out; 1078 } 1079 /* success */ 1080 r = 0; 1081 out: 1082 sshbuf_free(b); 1083 sshbuf_free(frombuf); 1084 sshbuf_free(tobuf); 1085 return r; 1086 } 1087 1088 static int 1089 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1090 struct dest_constraint **dcsp, size_t *ndcsp) 1091 { 1092 char *ext_name = NULL; 1093 int r; 1094 struct sshbuf *b = NULL; 1095 1096 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1097 error_fr(r, "parse constraint extension"); 1098 goto out; 1099 } 1100 debug_f("constraint ext %s", ext_name); 1101 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1102 if (sk_providerp == NULL) { 1103 error_f("%s not valid here", ext_name); 1104 r = SSH_ERR_INVALID_FORMAT; 1105 goto out; 1106 } 1107 if (*sk_providerp != NULL) { 1108 error_f("%s already set", ext_name); 1109 r = SSH_ERR_INVALID_FORMAT; 1110 goto out; 1111 } 1112 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1113 error_fr(r, "parse %s", ext_name); 1114 goto out; 1115 } 1116 } else if (strcmp(ext_name, 1117 "restrict-destination-v00@openssh.com") == 0) { 1118 if (*dcsp != NULL) { 1119 error_f("%s already set", ext_name); 1120 goto out; 1121 } 1122 if ((r = sshbuf_froms(m, &b)) != 0) { 1123 error_fr(r, "parse %s outer", ext_name); 1124 goto out; 1125 } 1126 while (sshbuf_len(b) != 0) { 1127 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1128 error_f("too many %s constraints", ext_name); 1129 goto out; 1130 } 1131 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1132 sizeof(**dcsp)); 1133 if ((r = parse_dest_constraint(b, 1134 *dcsp + (*ndcsp)++)) != 0) 1135 goto out; /* error already logged */ 1136 } 1137 } else { 1138 error_f("unsupported constraint \"%s\"", ext_name); 1139 r = SSH_ERR_FEATURE_UNSUPPORTED; 1140 goto out; 1141 } 1142 /* success */ 1143 r = 0; 1144 out: 1145 free(ext_name); 1146 sshbuf_free(b); 1147 return r; 1148 } 1149 1150 static int 1151 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1152 u_int *secondsp, int *confirmp, char **sk_providerp, 1153 struct dest_constraint **dcsp, size_t *ndcsp) 1154 { 1155 u_char ctype; 1156 int r; 1157 u_int seconds, maxsign = 0; 1158 1159 while (sshbuf_len(m)) { 1160 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1161 error_fr(r, "parse constraint type"); 1162 goto out; 1163 } 1164 switch (ctype) { 1165 case SSH_AGENT_CONSTRAIN_LIFETIME: 1166 if (*deathp != 0) { 1167 error_f("lifetime already set"); 1168 r = SSH_ERR_INVALID_FORMAT; 1169 goto out; 1170 } 1171 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1172 error_fr(r, "parse lifetime constraint"); 1173 goto out; 1174 } 1175 *deathp = monotime() + seconds; 1176 *secondsp = seconds; 1177 break; 1178 case SSH_AGENT_CONSTRAIN_CONFIRM: 1179 if (*confirmp != 0) { 1180 error_f("confirm already set"); 1181 r = SSH_ERR_INVALID_FORMAT; 1182 goto out; 1183 } 1184 *confirmp = 1; 1185 break; 1186 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1187 if (k == NULL) { 1188 error_f("maxsign not valid here"); 1189 r = SSH_ERR_INVALID_FORMAT; 1190 goto out; 1191 } 1192 if (maxsign != 0) { 1193 error_f("maxsign already set"); 1194 r = SSH_ERR_INVALID_FORMAT; 1195 goto out; 1196 } 1197 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1198 error_fr(r, "parse maxsign constraint"); 1199 goto out; 1200 } 1201 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1202 error_fr(r, "enable maxsign"); 1203 goto out; 1204 } 1205 break; 1206 case SSH_AGENT_CONSTRAIN_EXTENSION: 1207 if ((r = parse_key_constraint_extension(m, 1208 sk_providerp, dcsp, ndcsp)) != 0) 1209 goto out; /* error already logged */ 1210 break; 1211 default: 1212 error_f("Unknown constraint %d", ctype); 1213 r = SSH_ERR_FEATURE_UNSUPPORTED; 1214 goto out; 1215 } 1216 } 1217 /* success */ 1218 r = 0; 1219 out: 1220 return r; 1221 } 1222 1223 static void 1224 process_add_identity(SocketEntry *e) 1225 { 1226 Identity *id; 1227 int success = 0, confirm = 0; 1228 char *fp, *comment = NULL, *sk_provider = NULL; 1229 char canonical_provider[PATH_MAX]; 1230 time_t death = 0; 1231 u_int seconds = 0; 1232 struct dest_constraint *dest_constraints = NULL; 1233 size_t ndest_constraints = 0; 1234 struct sshkey *k = NULL; 1235 int r = SSH_ERR_INTERNAL_ERROR; 1236 1237 debug2_f("entering"); 1238 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1239 k == NULL || 1240 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1241 error_fr(r, "parse"); 1242 goto out; 1243 } 1244 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1245 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1246 error_f("failed to parse constraints"); 1247 sshbuf_reset(e->request); 1248 goto out; 1249 } 1250 1251 if (sk_provider != NULL) { 1252 if (!sshkey_is_sk(k)) { 1253 error("Cannot add provider: %s is not an " 1254 "authenticator-hosted key", sshkey_type(k)); 1255 goto out; 1256 } 1257 if (strcasecmp(sk_provider, "internal") == 0) { 1258 debug_f("internal provider"); 1259 } else { 1260 if (realpath(sk_provider, canonical_provider) == NULL) { 1261 verbose("failed provider \"%.100s\": " 1262 "realpath: %s", sk_provider, 1263 strerror(errno)); 1264 goto out; 1265 } 1266 free(sk_provider); 1267 sk_provider = xstrdup(canonical_provider); 1268 if (match_pattern_list(sk_provider, 1269 allowed_providers, 0) != 1) { 1270 error("Refusing add key: " 1271 "provider %s not allowed", sk_provider); 1272 goto out; 1273 } 1274 } 1275 } 1276 if ((r = sshkey_shield_private(k)) != 0) { 1277 error_fr(r, "shield private"); 1278 goto out; 1279 } 1280 if (lifetime && !death) 1281 death = monotime() + lifetime; 1282 if ((id = lookup_identity(k)) == NULL) { 1283 id = xcalloc(1, sizeof(Identity)); 1284 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1285 /* Increment the number of identities. */ 1286 idtab->nentries++; 1287 } else { 1288 /* identity not visible, do not update */ 1289 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1290 goto out; /* error already logged */ 1291 /* key state might have been updated */ 1292 sshkey_free(id->key); 1293 free(id->comment); 1294 free(id->sk_provider); 1295 free_dest_constraints(id->dest_constraints, 1296 id->ndest_constraints); 1297 } 1298 /* success */ 1299 id->key = k; 1300 id->comment = comment; 1301 id->death = death; 1302 id->confirm = confirm; 1303 id->sk_provider = sk_provider; 1304 id->dest_constraints = dest_constraints; 1305 id->ndest_constraints = ndest_constraints; 1306 1307 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1308 SSH_FP_DEFAULT)) == NULL) 1309 fatal_f("sshkey_fingerprint failed"); 1310 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1311 "(provider: %s) (destination constraints: %zu)", 1312 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1313 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1314 free(fp); 1315 /* transferred */ 1316 k = NULL; 1317 comment = NULL; 1318 sk_provider = NULL; 1319 dest_constraints = NULL; 1320 ndest_constraints = 0; 1321 success = 1; 1322 out: 1323 free(sk_provider); 1324 free(comment); 1325 sshkey_free(k); 1326 free_dest_constraints(dest_constraints, ndest_constraints); 1327 send_status(e, success); 1328 } 1329 1330 /* XXX todo: encrypt sensitive data with passphrase */ 1331 static void 1332 process_lock_agent(SocketEntry *e, int lock) 1333 { 1334 int r, success = 0, delay; 1335 char *passwd; 1336 u_char passwdhash[LOCK_SIZE]; 1337 static u_int fail_count = 0; 1338 size_t pwlen; 1339 1340 debug2_f("entering"); 1341 /* 1342 * This is deliberately fatal: the user has requested that we lock, 1343 * but we can't parse their request properly. The only safe thing to 1344 * do is abort. 1345 */ 1346 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1347 fatal_fr(r, "parse"); 1348 if (pwlen == 0) { 1349 debug("empty password not supported"); 1350 } else if (locked && !lock) { 1351 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1352 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1353 fatal("bcrypt_pbkdf"); 1354 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1355 debug("agent unlocked"); 1356 locked = 0; 1357 fail_count = 0; 1358 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1359 success = 1; 1360 } else { 1361 /* delay in 0.1s increments up to 10s */ 1362 if (fail_count < 100) 1363 fail_count++; 1364 delay = 100000 * fail_count; 1365 debug("unlock failed, delaying %0.1lf seconds", 1366 (double)delay/1000000); 1367 usleep(delay); 1368 } 1369 explicit_bzero(passwdhash, sizeof(passwdhash)); 1370 } else if (!locked && lock) { 1371 debug("agent locked"); 1372 locked = 1; 1373 arc4random_buf(lock_salt, sizeof(lock_salt)); 1374 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1375 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1376 fatal("bcrypt_pbkdf"); 1377 success = 1; 1378 } 1379 freezero(passwd, pwlen); 1380 send_status(e, success); 1381 } 1382 1383 static void 1384 no_identities(SocketEntry *e) 1385 { 1386 struct sshbuf *msg; 1387 int r; 1388 1389 if ((msg = sshbuf_new()) == NULL) 1390 fatal_f("sshbuf_new failed"); 1391 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1392 (r = sshbuf_put_u32(msg, 0)) != 0 || 1393 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1394 fatal_fr(r, "compose"); 1395 sshbuf_free(msg); 1396 } 1397 1398 #ifdef ENABLE_PKCS11 1399 static void 1400 process_add_smartcard_key(SocketEntry *e) 1401 { 1402 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1403 char **comments = NULL; 1404 int r, i, count = 0, success = 0, confirm = 0; 1405 u_int seconds = 0; 1406 time_t death = 0; 1407 struct sshkey **keys = NULL, *k; 1408 Identity *id; 1409 struct dest_constraint *dest_constraints = NULL; 1410 size_t ndest_constraints = 0; 1411 1412 debug2_f("entering"); 1413 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1414 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1415 error_fr(r, "parse"); 1416 goto send; 1417 } 1418 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1419 NULL, &dest_constraints, &ndest_constraints) != 0) { 1420 error_f("failed to parse constraints"); 1421 goto send; 1422 } 1423 if (realpath(provider, canonical_provider) == NULL) { 1424 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1425 provider, strerror(errno)); 1426 goto send; 1427 } 1428 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1429 verbose("refusing PKCS#11 add of \"%.100s\": " 1430 "provider not allowed", canonical_provider); 1431 goto send; 1432 } 1433 debug_f("add %.100s", canonical_provider); 1434 if (lifetime && !death) 1435 death = monotime() + lifetime; 1436 1437 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1438 for (i = 0; i < count; i++) { 1439 k = keys[i]; 1440 if (lookup_identity(k) == NULL) { 1441 id = xcalloc(1, sizeof(Identity)); 1442 id->key = k; 1443 keys[i] = NULL; /* transferred */ 1444 id->provider = xstrdup(canonical_provider); 1445 if (*comments[i] != '\0') { 1446 id->comment = comments[i]; 1447 comments[i] = NULL; /* transferred */ 1448 } else { 1449 id->comment = xstrdup(canonical_provider); 1450 } 1451 id->death = death; 1452 id->confirm = confirm; 1453 id->dest_constraints = dest_constraints; 1454 id->ndest_constraints = ndest_constraints; 1455 dest_constraints = NULL; /* transferred */ 1456 ndest_constraints = 0; 1457 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1458 idtab->nentries++; 1459 success = 1; 1460 } 1461 /* XXX update constraints for existing keys */ 1462 sshkey_free(keys[i]); 1463 free(comments[i]); 1464 } 1465 send: 1466 free(pin); 1467 free(provider); 1468 free(keys); 1469 free(comments); 1470 free_dest_constraints(dest_constraints, ndest_constraints); 1471 send_status(e, success); 1472 } 1473 1474 static void 1475 process_remove_smartcard_key(SocketEntry *e) 1476 { 1477 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1478 int r, success = 0; 1479 Identity *id, *nxt; 1480 1481 debug2_f("entering"); 1482 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1483 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1484 error_fr(r, "parse"); 1485 goto send; 1486 } 1487 free(pin); 1488 1489 if (realpath(provider, canonical_provider) == NULL) { 1490 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1491 provider, strerror(errno)); 1492 goto send; 1493 } 1494 1495 debug_f("remove %.100s", canonical_provider); 1496 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1497 nxt = TAILQ_NEXT(id, next); 1498 /* Skip file--based keys */ 1499 if (id->provider == NULL) 1500 continue; 1501 if (!strcmp(canonical_provider, id->provider)) { 1502 TAILQ_REMOVE(&idtab->idlist, id, next); 1503 free_identity(id); 1504 idtab->nentries--; 1505 } 1506 } 1507 if (pkcs11_del_provider(canonical_provider) == 0) 1508 success = 1; 1509 else 1510 error_f("pkcs11_del_provider failed"); 1511 send: 1512 free(provider); 1513 send_status(e, success); 1514 } 1515 #endif /* ENABLE_PKCS11 */ 1516 1517 static int 1518 process_ext_session_bind(SocketEntry *e) 1519 { 1520 int r, sid_match, key_match; 1521 struct sshkey *key = NULL; 1522 struct sshbuf *sid = NULL, *sig = NULL; 1523 char *fp = NULL; 1524 size_t i; 1525 u_char fwd = 0; 1526 1527 debug2_f("entering"); 1528 if ((r = sshkey_froms(e->request, &key)) != 0 || 1529 (r = sshbuf_froms(e->request, &sid)) != 0 || 1530 (r = sshbuf_froms(e->request, &sig)) != 0 || 1531 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1532 error_fr(r, "parse"); 1533 goto out; 1534 } 1535 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1536 SSH_FP_DEFAULT)) == NULL) 1537 fatal_f("fingerprint failed"); 1538 /* check signature with hostkey on session ID */ 1539 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1540 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1541 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1542 goto out; 1543 } 1544 /* check whether sid/key already recorded */ 1545 for (i = 0; i < e->nsession_ids; i++) { 1546 if (!e->session_ids[i].forwarded) { 1547 error_f("attempt to bind session ID to socket " 1548 "previously bound for authentication attempt"); 1549 r = -1; 1550 goto out; 1551 } 1552 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1553 key_match = sshkey_equal(key, e->session_ids[i].key); 1554 if (sid_match && key_match) { 1555 debug_f("session ID already recorded for %s %s", 1556 sshkey_type(key), fp); 1557 r = 0; 1558 goto out; 1559 } else if (sid_match) { 1560 error_f("session ID recorded against different key " 1561 "for %s %s", sshkey_type(key), fp); 1562 r = -1; 1563 goto out; 1564 } 1565 /* 1566 * new sid with previously-seen key can happen, e.g. multiple 1567 * connections to the same host. 1568 */ 1569 } 1570 /* record new key/sid */ 1571 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1572 error_f("too many session IDs recorded"); 1573 goto out; 1574 } 1575 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1576 e->nsession_ids + 1, sizeof(*e->session_ids)); 1577 i = e->nsession_ids++; 1578 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1579 AGENT_MAX_SESSION_IDS); 1580 e->session_ids[i].key = key; 1581 e->session_ids[i].forwarded = fwd != 0; 1582 key = NULL; /* transferred */ 1583 /* can't transfer sid; it's refcounted and scoped to request's life */ 1584 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1585 fatal_f("sshbuf_new"); 1586 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1587 fatal_fr(r, "sshbuf_putb session ID"); 1588 /* success */ 1589 r = 0; 1590 out: 1591 sshkey_free(key); 1592 sshbuf_free(sid); 1593 sshbuf_free(sig); 1594 return r == 0 ? 1 : 0; 1595 } 1596 1597 static void 1598 process_extension(SocketEntry *e) 1599 { 1600 int r, success = 0; 1601 char *name; 1602 1603 debug2_f("entering"); 1604 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1605 error_fr(r, "parse"); 1606 goto send; 1607 } 1608 if (strcmp(name, "session-bind@openssh.com") == 0) 1609 success = process_ext_session_bind(e); 1610 else 1611 debug_f("unsupported extension \"%s\"", name); 1612 free(name); 1613 send: 1614 send_status(e, success); 1615 } 1616 /* 1617 * dispatch incoming message. 1618 * returns 1 on success, 0 for incomplete messages or -1 on error. 1619 */ 1620 static int 1621 process_message(u_int socknum) 1622 { 1623 u_int msg_len; 1624 u_char type; 1625 const u_char *cp; 1626 int r; 1627 SocketEntry *e; 1628 1629 if (socknum >= sockets_alloc) 1630 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1631 e = &sockets[socknum]; 1632 1633 if (sshbuf_len(e->input) < 5) 1634 return 0; /* Incomplete message header. */ 1635 cp = sshbuf_ptr(e->input); 1636 msg_len = PEEK_U32(cp); 1637 if (msg_len > AGENT_MAX_LEN) { 1638 debug_f("socket %u (fd=%d) message too long %u > %u", 1639 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1640 return -1; 1641 } 1642 if (sshbuf_len(e->input) < msg_len + 4) 1643 return 0; /* Incomplete message body. */ 1644 1645 /* move the current input to e->request */ 1646 sshbuf_reset(e->request); 1647 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1648 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1649 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1650 r == SSH_ERR_STRING_TOO_LARGE) { 1651 error_fr(r, "parse"); 1652 return -1; 1653 } 1654 fatal_fr(r, "parse"); 1655 } 1656 1657 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1658 1659 /* check whether agent is locked */ 1660 if (locked && type != SSH_AGENTC_UNLOCK) { 1661 sshbuf_reset(e->request); 1662 switch (type) { 1663 case SSH2_AGENTC_REQUEST_IDENTITIES: 1664 /* send empty lists */ 1665 no_identities(e); 1666 break; 1667 default: 1668 /* send a fail message for all other request types */ 1669 send_status(e, 0); 1670 } 1671 return 1; 1672 } 1673 1674 switch (type) { 1675 case SSH_AGENTC_LOCK: 1676 case SSH_AGENTC_UNLOCK: 1677 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1678 break; 1679 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1680 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1681 break; 1682 /* ssh2 */ 1683 case SSH2_AGENTC_SIGN_REQUEST: 1684 process_sign_request2(e); 1685 break; 1686 case SSH2_AGENTC_REQUEST_IDENTITIES: 1687 process_request_identities(e); 1688 break; 1689 case SSH2_AGENTC_ADD_IDENTITY: 1690 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1691 process_add_identity(e); 1692 break; 1693 case SSH2_AGENTC_REMOVE_IDENTITY: 1694 process_remove_identity(e); 1695 break; 1696 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1697 process_remove_all_identities(e); 1698 break; 1699 #ifdef ENABLE_PKCS11 1700 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1701 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1702 process_add_smartcard_key(e); 1703 break; 1704 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1705 process_remove_smartcard_key(e); 1706 break; 1707 #endif /* ENABLE_PKCS11 */ 1708 case SSH_AGENTC_EXTENSION: 1709 process_extension(e); 1710 break; 1711 default: 1712 /* Unknown message. Respond with failure. */ 1713 error("Unknown message %d", type); 1714 sshbuf_reset(e->request); 1715 send_status(e, 0); 1716 break; 1717 } 1718 return 1; 1719 } 1720 1721 static void 1722 new_socket(sock_type type, int fd) 1723 { 1724 u_int i, old_alloc, new_alloc; 1725 1726 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1727 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1728 if (type == AUTH_CONNECTION) { 1729 debug("xcount %d -> %d", xcount, xcount + 1); 1730 ++xcount; 1731 } 1732 set_nonblock(fd); 1733 1734 if (fd > max_fd) 1735 max_fd = fd; 1736 1737 for (i = 0; i < sockets_alloc; i++) 1738 if (sockets[i].type == AUTH_UNUSED) { 1739 sockets[i].fd = fd; 1740 if ((sockets[i].input = sshbuf_new()) == NULL || 1741 (sockets[i].output = sshbuf_new()) == NULL || 1742 (sockets[i].request = sshbuf_new()) == NULL) 1743 fatal_f("sshbuf_new failed"); 1744 sockets[i].type = type; 1745 return; 1746 } 1747 old_alloc = sockets_alloc; 1748 new_alloc = sockets_alloc + 10; 1749 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1750 sizeof(sockets[0])); 1751 for (i = old_alloc; i < new_alloc; i++) 1752 sockets[i].type = AUTH_UNUSED; 1753 sockets_alloc = new_alloc; 1754 sockets[old_alloc].fd = fd; 1755 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1756 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1757 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1758 fatal_f("sshbuf_new failed"); 1759 sockets[old_alloc].type = type; 1760 } 1761 1762 static int 1763 handle_socket_read(u_int socknum) 1764 { 1765 struct sockaddr_un sunaddr; 1766 socklen_t slen; 1767 uid_t euid; 1768 gid_t egid; 1769 int fd; 1770 1771 slen = sizeof(sunaddr); 1772 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1773 if (fd == -1) { 1774 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1775 return -1; 1776 } 1777 if (getpeereid(fd, &euid, &egid) == -1) { 1778 error("getpeereid %d failed: %s", fd, strerror(errno)); 1779 close(fd); 1780 return -1; 1781 } 1782 if ((euid != 0) && (getuid() != euid)) { 1783 error("uid mismatch: peer euid %u != uid %u", 1784 (u_int) euid, (u_int) getuid()); 1785 close(fd); 1786 return -1; 1787 } 1788 new_socket(AUTH_CONNECTION, fd); 1789 return 0; 1790 } 1791 1792 static int 1793 handle_conn_read(u_int socknum) 1794 { 1795 char buf[AGENT_RBUF_LEN]; 1796 ssize_t len; 1797 int r; 1798 1799 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1800 if (len == -1) { 1801 if (errno == EAGAIN || errno == EINTR) 1802 return 0; 1803 error_f("read error on socket %u (fd %d): %s", 1804 socknum, sockets[socknum].fd, strerror(errno)); 1805 } 1806 return -1; 1807 } 1808 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1809 fatal_fr(r, "compose"); 1810 explicit_bzero(buf, sizeof(buf)); 1811 for (;;) { 1812 if ((r = process_message(socknum)) == -1) 1813 return -1; 1814 else if (r == 0) 1815 break; 1816 } 1817 return 0; 1818 } 1819 1820 static int 1821 handle_conn_write(u_int socknum) 1822 { 1823 ssize_t len; 1824 int r; 1825 1826 if (sshbuf_len(sockets[socknum].output) == 0) 1827 return 0; /* shouldn't happen */ 1828 if ((len = write(sockets[socknum].fd, 1829 sshbuf_ptr(sockets[socknum].output), 1830 sshbuf_len(sockets[socknum].output))) <= 0) { 1831 if (len == -1) { 1832 if (errno == EAGAIN || errno == EINTR) 1833 return 0; 1834 error_f("read error on socket %u (fd %d): %s", 1835 socknum, sockets[socknum].fd, strerror(errno)); 1836 } 1837 return -1; 1838 } 1839 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1840 fatal_fr(r, "consume"); 1841 return 0; 1842 } 1843 1844 static void 1845 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1846 { 1847 size_t i; 1848 u_int socknum, activefds = npfd; 1849 1850 for (i = 0; i < npfd; i++) { 1851 if (pfd[i].revents == 0) 1852 continue; 1853 /* Find sockets entry */ 1854 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1855 if (sockets[socknum].type != AUTH_SOCKET && 1856 sockets[socknum].type != AUTH_CONNECTION) 1857 continue; 1858 if (pfd[i].fd == sockets[socknum].fd) 1859 break; 1860 } 1861 if (socknum >= sockets_alloc) { 1862 error_f("no socket for fd %d", pfd[i].fd); 1863 continue; 1864 } 1865 /* Process events */ 1866 switch (sockets[socknum].type) { 1867 case AUTH_SOCKET: 1868 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1869 break; 1870 if (npfd > maxfds) { 1871 debug3("out of fds (active %u >= limit %u); " 1872 "skipping accept", activefds, maxfds); 1873 break; 1874 } 1875 if (handle_socket_read(socknum) == 0) 1876 activefds++; 1877 break; 1878 case AUTH_CONNECTION: 1879 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1880 handle_conn_read(socknum) != 0) 1881 goto close_sock; 1882 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1883 handle_conn_write(socknum) != 0) { 1884 close_sock: 1885 if (activefds == 0) 1886 fatal("activefds == 0 at close_sock"); 1887 close_socket(&sockets[socknum]); 1888 activefds--; 1889 break; 1890 } 1891 break; 1892 default: 1893 break; 1894 } 1895 } 1896 } 1897 1898 static int 1899 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1900 { 1901 struct pollfd *pfd = *pfdp; 1902 size_t i, j, npfd = 0; 1903 time_t deadline; 1904 int r; 1905 1906 /* Count active sockets */ 1907 for (i = 0; i < sockets_alloc; i++) { 1908 switch (sockets[i].type) { 1909 case AUTH_SOCKET: 1910 case AUTH_CONNECTION: 1911 npfd++; 1912 break; 1913 case AUTH_UNUSED: 1914 break; 1915 default: 1916 fatal("Unknown socket type %d", sockets[i].type); 1917 break; 1918 } 1919 } 1920 if (npfd != *npfdp && 1921 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1922 fatal_f("recallocarray failed"); 1923 *pfdp = pfd; 1924 *npfdp = npfd; 1925 1926 for (i = j = 0; i < sockets_alloc; i++) { 1927 switch (sockets[i].type) { 1928 case AUTH_SOCKET: 1929 if (npfd > maxfds) { 1930 debug3("out of fds (active %zu >= limit %u); " 1931 "skipping arming listener", npfd, maxfds); 1932 break; 1933 } 1934 pfd[j].fd = sockets[i].fd; 1935 pfd[j].revents = 0; 1936 pfd[j].events = POLLIN; 1937 j++; 1938 break; 1939 case AUTH_CONNECTION: 1940 pfd[j].fd = sockets[i].fd; 1941 pfd[j].revents = 0; 1942 /* 1943 * Only prepare to read if we can handle a full-size 1944 * input read buffer and enqueue a max size reply.. 1945 */ 1946 if ((r = sshbuf_check_reserve(sockets[i].input, 1947 AGENT_RBUF_LEN)) == 0 && 1948 (r = sshbuf_check_reserve(sockets[i].output, 1949 AGENT_MAX_LEN)) == 0) 1950 pfd[j].events = POLLIN; 1951 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1952 fatal_fr(r, "reserve"); 1953 if (sshbuf_len(sockets[i].output) > 0) 1954 pfd[j].events |= POLLOUT; 1955 j++; 1956 break; 1957 default: 1958 break; 1959 } 1960 } 1961 deadline = reaper(); 1962 if (parent_alive_interval != 0) 1963 deadline = (deadline == 0) ? parent_alive_interval : 1964 MINIMUM(deadline, parent_alive_interval); 1965 if (deadline == 0) { 1966 *timeoutp = -1; /* INFTIM */ 1967 } else { 1968 if (deadline > INT_MAX / 1000) 1969 *timeoutp = INT_MAX / 1000; 1970 else 1971 *timeoutp = deadline * 1000; 1972 } 1973 return (1); 1974 } 1975 1976 static void 1977 cleanup_socket(void) 1978 { 1979 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1980 return; 1981 debug_f("cleanup"); 1982 if (socket_name[0]) 1983 unlink(socket_name); 1984 if (socket_dir[0]) 1985 rmdir(socket_dir); 1986 } 1987 1988 void 1989 cleanup_exit(int i) 1990 { 1991 cleanup_socket(); 1992 _exit(i); 1993 } 1994 1995 /*ARGSUSED*/ 1996 static void 1997 cleanup_handler(int sig) 1998 { 1999 cleanup_socket(); 2000 #ifdef ENABLE_PKCS11 2001 pkcs11_terminate(); 2002 #endif 2003 _exit(2); 2004 } 2005 2006 static void 2007 check_parent_exists(void) 2008 { 2009 /* 2010 * If our parent has exited then getppid() will return (pid_t)1, 2011 * so testing for that should be safe. 2012 */ 2013 if (parent_pid != -1 && getppid() != parent_pid) { 2014 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2015 cleanup_socket(); 2016 _exit(2); 2017 } 2018 } 2019 2020 static void 2021 usage(void) 2022 { 2023 fprintf(stderr, 2024 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2025 " [-P allowed_providers] [-t life]\n" 2026 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 2027 " [-t life] command [arg ...]\n" 2028 " ssh-agent [-c | -s] -k\n"); 2029 exit(1); 2030 } 2031 2032 int 2033 main(int ac, char **av) 2034 { 2035 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2036 int sock, ch, result, saved_errno; 2037 char *shell, *format, *pidstr, *agentsocket = NULL; 2038 #ifdef HAVE_SETRLIMIT 2039 struct rlimit rlim; 2040 #endif 2041 extern int optind; 2042 extern char *optarg; 2043 pid_t pid; 2044 char pidstrbuf[1 + 3 * sizeof pid]; 2045 size_t len; 2046 mode_t prev_mask; 2047 int timeout = -1; /* INFTIM */ 2048 struct pollfd *pfd = NULL; 2049 size_t npfd = 0; 2050 u_int maxfds; 2051 2052 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2053 sanitise_stdfd(); 2054 2055 /* drop */ 2056 setegid(getgid()); 2057 setgid(getgid()); 2058 setuid(geteuid()); 2059 2060 platform_disable_tracing(0); /* strict=no */ 2061 2062 #ifdef RLIMIT_NOFILE 2063 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2064 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2065 #endif 2066 2067 __progname = ssh_get_progname(av[0]); 2068 seed_rng(); 2069 2070 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2071 switch (ch) { 2072 case 'E': 2073 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2074 if (fingerprint_hash == -1) 2075 fatal("Invalid hash algorithm \"%s\"", optarg); 2076 break; 2077 case 'c': 2078 if (s_flag) 2079 usage(); 2080 c_flag++; 2081 break; 2082 case 'k': 2083 k_flag++; 2084 break; 2085 case 'O': 2086 if (strcmp(optarg, "no-restrict-websafe") == 0) 2087 restrict_websafe = 0; 2088 else 2089 fatal("Unknown -O option"); 2090 break; 2091 case 'P': 2092 if (allowed_providers != NULL) 2093 fatal("-P option already specified"); 2094 allowed_providers = xstrdup(optarg); 2095 break; 2096 case 's': 2097 if (c_flag) 2098 usage(); 2099 s_flag++; 2100 break; 2101 case 'd': 2102 if (d_flag || D_flag) 2103 usage(); 2104 d_flag++; 2105 break; 2106 case 'D': 2107 if (d_flag || D_flag) 2108 usage(); 2109 D_flag++; 2110 break; 2111 case 'a': 2112 agentsocket = optarg; 2113 break; 2114 case 't': 2115 if ((lifetime = convtime(optarg)) == -1) { 2116 fprintf(stderr, "Invalid lifetime\n"); 2117 usage(); 2118 } 2119 break; 2120 case 'x': 2121 xcount = 0; 2122 break; 2123 default: 2124 usage(); 2125 } 2126 } 2127 ac -= optind; 2128 av += optind; 2129 2130 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2131 usage(); 2132 2133 if (allowed_providers == NULL) 2134 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2135 2136 if (ac == 0 && !c_flag && !s_flag) { 2137 shell = getenv("SHELL"); 2138 if (shell != NULL && (len = strlen(shell)) > 2 && 2139 strncmp(shell + len - 3, "csh", 3) == 0) 2140 c_flag = 1; 2141 } 2142 if (k_flag) { 2143 const char *errstr = NULL; 2144 2145 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2146 if (pidstr == NULL) { 2147 fprintf(stderr, "%s not set, cannot kill agent\n", 2148 SSH_AGENTPID_ENV_NAME); 2149 exit(1); 2150 } 2151 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2152 if (errstr) { 2153 fprintf(stderr, 2154 "%s=\"%s\", which is not a good PID: %s\n", 2155 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2156 exit(1); 2157 } 2158 if (kill(pid, SIGTERM) == -1) { 2159 perror("kill"); 2160 exit(1); 2161 } 2162 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2163 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2164 printf(format, SSH_AGENTPID_ENV_NAME); 2165 printf("echo Agent pid %ld killed;\n", (long)pid); 2166 exit(0); 2167 } 2168 2169 /* 2170 * Minimum file descriptors: 2171 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2172 * a few spare for libc / stack protectors / sanitisers, etc. 2173 */ 2174 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2175 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2176 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2177 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2178 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2179 2180 parent_pid = getpid(); 2181 2182 if (agentsocket == NULL) { 2183 /* Create private directory for agent socket */ 2184 mktemp_proto(socket_dir, sizeof(socket_dir)); 2185 if (mkdtemp(socket_dir) == NULL) { 2186 perror("mkdtemp: private socket dir"); 2187 exit(1); 2188 } 2189 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2190 (long)parent_pid); 2191 } else { 2192 /* Try to use specified agent socket */ 2193 socket_dir[0] = '\0'; 2194 strlcpy(socket_name, agentsocket, sizeof socket_name); 2195 } 2196 2197 /* 2198 * Create socket early so it will exist before command gets run from 2199 * the parent. 2200 */ 2201 prev_mask = umask(0177); 2202 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2203 if (sock < 0) { 2204 /* XXX - unix_listener() calls error() not perror() */ 2205 *socket_name = '\0'; /* Don't unlink any existing file */ 2206 cleanup_exit(1); 2207 } 2208 umask(prev_mask); 2209 2210 /* 2211 * Fork, and have the parent execute the command, if any, or present 2212 * the socket data. The child continues as the authentication agent. 2213 */ 2214 if (D_flag || d_flag) { 2215 log_init(__progname, 2216 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2217 SYSLOG_FACILITY_AUTH, 1); 2218 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2219 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2220 SSH_AUTHSOCKET_ENV_NAME); 2221 printf("echo Agent pid %ld;\n", (long)parent_pid); 2222 fflush(stdout); 2223 goto skip; 2224 } 2225 pid = fork(); 2226 if (pid == -1) { 2227 perror("fork"); 2228 cleanup_exit(1); 2229 } 2230 if (pid != 0) { /* Parent - execute the given command. */ 2231 close(sock); 2232 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2233 if (ac == 0) { 2234 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2235 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2236 SSH_AUTHSOCKET_ENV_NAME); 2237 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2238 SSH_AGENTPID_ENV_NAME); 2239 printf("echo Agent pid %ld;\n", (long)pid); 2240 exit(0); 2241 } 2242 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2243 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2244 perror("setenv"); 2245 exit(1); 2246 } 2247 execvp(av[0], av); 2248 perror(av[0]); 2249 exit(1); 2250 } 2251 /* child */ 2252 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2253 2254 if (setsid() == -1) { 2255 error("setsid: %s", strerror(errno)); 2256 cleanup_exit(1); 2257 } 2258 2259 (void)chdir("/"); 2260 if (stdfd_devnull(1, 1, 1) == -1) 2261 error_f("stdfd_devnull failed"); 2262 2263 #ifdef HAVE_SETRLIMIT 2264 /* deny core dumps, since memory contains unencrypted private keys */ 2265 rlim.rlim_cur = rlim.rlim_max = 0; 2266 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2267 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2268 cleanup_exit(1); 2269 } 2270 #endif 2271 2272 skip: 2273 2274 cleanup_pid = getpid(); 2275 2276 #ifdef ENABLE_PKCS11 2277 pkcs11_init(0); 2278 #endif 2279 new_socket(AUTH_SOCKET, sock); 2280 if (ac > 0) 2281 parent_alive_interval = 10; 2282 idtab_init(); 2283 ssh_signal(SIGPIPE, SIG_IGN); 2284 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2285 ssh_signal(SIGHUP, cleanup_handler); 2286 ssh_signal(SIGTERM, cleanup_handler); 2287 2288 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2289 fatal("%s: pledge: %s", __progname, strerror(errno)); 2290 platform_pledge_agent(); 2291 2292 while (1) { 2293 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2294 result = poll(pfd, npfd, timeout); 2295 saved_errno = errno; 2296 if (parent_alive_interval != 0) 2297 check_parent_exists(); 2298 (void) reaper(); /* remove expired keys */ 2299 if (result == -1) { 2300 if (saved_errno == EINTR) 2301 continue; 2302 fatal("poll: %s", strerror(saved_errno)); 2303 } else if (result > 0) 2304 after_poll(pfd, npfd, maxfds); 2305 } 2306 /* NOTREACHED */ 2307 } 2308