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 __RCSID("$FreeBSD$"); 39 40 #include <sys/types.h> 41 #include <sys/resource.h> 42 #include <sys/stat.h> 43 #include <sys/socket.h> 44 #include <sys/wait.h> 45 #ifdef HAVE_SYS_TIME_H 46 # include <sys/time.h> 47 #endif 48 #ifdef HAVE_SYS_UN_H 49 # include <sys/un.h> 50 #endif 51 #include "openbsd-compat/sys-queue.h" 52 53 #ifdef WITH_OPENSSL 54 #include <openssl/evp.h> 55 #include "openbsd-compat/openssl-compat.h" 56 #endif 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <limits.h> 61 #ifdef HAVE_PATHS_H 62 # include <paths.h> 63 #endif 64 #ifdef HAVE_POLL_H 65 # include <poll.h> 66 #endif 67 #include <signal.h> 68 #include <stdarg.h> 69 #include <stdio.h> 70 #include <stdlib.h> 71 #include <time.h> 72 #include <string.h> 73 #include <unistd.h> 74 #ifdef HAVE_UTIL_H 75 # include <util.h> 76 #endif 77 78 #include "xmalloc.h" 79 #include "ssh.h" 80 #include "ssh2.h" 81 #include "sshbuf.h" 82 #include "sshkey.h" 83 #include "authfd.h" 84 #include "compat.h" 85 #include "log.h" 86 #include "misc.h" 87 #include "digest.h" 88 #include "ssherr.h" 89 #include "match.h" 90 #include "msg.h" 91 #include "ssherr.h" 92 #include "pathnames.h" 93 #include "ssh-pkcs11.h" 94 #include "sk-api.h" 95 #include "myproposal.h" 96 97 #ifndef DEFAULT_ALLOWED_PROVIDERS 98 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 99 #endif 100 101 /* Maximum accepted message length */ 102 #define AGENT_MAX_LEN (256*1024) 103 /* Maximum bytes to read from client socket */ 104 #define AGENT_RBUF_LEN (4096) 105 /* Maximum number of recorded session IDs/hostkeys per connection */ 106 #define AGENT_MAX_SESSION_IDS 16 107 /* Maximum size of session ID */ 108 #define AGENT_MAX_SID_LEN 128 109 /* Maximum number of destination constraints to accept on a key */ 110 #define AGENT_MAX_DEST_CONSTRAINTS 1024 111 112 /* XXX store hostkey_sid in a refcounted tree */ 113 114 typedef enum { 115 AUTH_UNUSED = 0, 116 AUTH_SOCKET = 1, 117 AUTH_CONNECTION = 2, 118 } sock_type; 119 120 struct hostkey_sid { 121 struct sshkey *key; 122 struct sshbuf *sid; 123 int forwarded; 124 }; 125 126 typedef struct socket_entry { 127 int fd; 128 sock_type type; 129 struct sshbuf *input; 130 struct sshbuf *output; 131 struct sshbuf *request; 132 size_t nsession_ids; 133 struct hostkey_sid *session_ids; 134 } SocketEntry; 135 136 u_int sockets_alloc = 0; 137 SocketEntry *sockets = NULL; 138 139 typedef struct identity { 140 TAILQ_ENTRY(identity) next; 141 struct sshkey *key; 142 char *comment; 143 char *provider; 144 time_t death; 145 u_int confirm; 146 char *sk_provider; 147 struct dest_constraint *dest_constraints; 148 size_t ndest_constraints; 149 } Identity; 150 151 struct idtable { 152 int nentries; 153 TAILQ_HEAD(idqueue, identity) idlist; 154 }; 155 156 /* private key table */ 157 struct idtable *idtab; 158 159 int max_fd = 0; 160 161 /* pid of shell == parent of agent */ 162 pid_t parent_pid = -1; 163 time_t parent_alive_interval = 0; 164 165 /* pid of process for which cleanup_socket is applicable */ 166 pid_t cleanup_pid = 0; 167 168 /* pathname and directory for AUTH_SOCKET */ 169 char socket_name[PATH_MAX]; 170 char socket_dir[PATH_MAX]; 171 172 /* Pattern-list of allowed PKCS#11/Security key paths */ 173 static char *allowed_providers; 174 175 /* locking */ 176 #define LOCK_SIZE 32 177 #define LOCK_SALT_SIZE 16 178 #define LOCK_ROUNDS 1 179 int locked = 0; 180 u_char lock_pwhash[LOCK_SIZE]; 181 u_char lock_salt[LOCK_SALT_SIZE]; 182 183 extern char *__progname; 184 185 /* Default lifetime in seconds (0 == forever) */ 186 static int lifetime = 0; 187 188 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 189 190 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 191 static int restrict_websafe = 1; 192 193 /* 194 * Client connection count; incremented in new_socket() and decremented in 195 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 196 * normally initialized to 1, it will never reach 0. However, if the -x 197 * option is specified, it is initialized to 0 in main(); in that case, 198 * ssh-agent will exit as soon as it has had at least one client but no 199 * longer has any. 200 */ 201 static int xcount = 1; 202 203 static void 204 close_socket(SocketEntry *e) 205 { 206 size_t i; 207 int last = 0; 208 209 if (e->type == AUTH_CONNECTION) { 210 debug("xcount %d -> %d", xcount, xcount - 1); 211 if (--xcount == 0) 212 last = 1; 213 } 214 close(e->fd); 215 sshbuf_free(e->input); 216 sshbuf_free(e->output); 217 sshbuf_free(e->request); 218 for (i = 0; i < e->nsession_ids; i++) { 219 sshkey_free(e->session_ids[i].key); 220 sshbuf_free(e->session_ids[i].sid); 221 } 222 free(e->session_ids); 223 memset(e, '\0', sizeof(*e)); 224 e->fd = -1; 225 e->type = AUTH_UNUSED; 226 if (last) 227 cleanup_exit(0); 228 } 229 230 static void 231 idtab_init(void) 232 { 233 idtab = xcalloc(1, sizeof(*idtab)); 234 TAILQ_INIT(&idtab->idlist); 235 idtab->nentries = 0; 236 } 237 238 static void 239 free_dest_constraint_hop(struct dest_constraint_hop *dch) 240 { 241 u_int i; 242 243 if (dch == NULL) 244 return; 245 free(dch->user); 246 free(dch->hostname); 247 for (i = 0; i < dch->nkeys; i++) 248 sshkey_free(dch->keys[i]); 249 free(dch->keys); 250 free(dch->key_is_ca); 251 } 252 253 static void 254 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 255 { 256 size_t i; 257 258 for (i = 0; i < ndcs; i++) { 259 free_dest_constraint_hop(&dcs[i].from); 260 free_dest_constraint_hop(&dcs[i].to); 261 } 262 free(dcs); 263 } 264 265 static void 266 free_identity(Identity *id) 267 { 268 sshkey_free(id->key); 269 free(id->provider); 270 free(id->comment); 271 free(id->sk_provider); 272 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 273 free(id); 274 } 275 276 /* 277 * Match 'key' against the key/CA list in a destination constraint hop 278 * Returns 0 on success or -1 otherwise. 279 */ 280 static int 281 match_key_hop(const char *tag, const struct sshkey *key, 282 const struct dest_constraint_hop *dch) 283 { 284 const char *reason = NULL; 285 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 286 u_int i; 287 char *fp; 288 289 if (key == NULL) 290 return -1; 291 /* XXX logspam */ 292 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 293 SSH_FP_DEFAULT)) == NULL) 294 fatal_f("fingerprint failed"); 295 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 296 tag, hostname, sshkey_type(key), fp, dch->nkeys); 297 free(fp); 298 for (i = 0; i < dch->nkeys; i++) { 299 if (dch->keys[i] == NULL) 300 return -1; 301 /* XXX logspam */ 302 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 303 SSH_FP_DEFAULT)) == NULL) 304 fatal_f("fingerprint failed"); 305 debug3_f("%s: key %u: %s%s %s", tag, i, 306 dch->key_is_ca[i] ? "CA " : "", 307 sshkey_type(dch->keys[i]), fp); 308 free(fp); 309 if (!sshkey_is_cert(key)) { 310 /* plain key */ 311 if (dch->key_is_ca[i] || 312 !sshkey_equal(key, dch->keys[i])) 313 continue; 314 return 0; 315 } 316 /* certificate */ 317 if (!dch->key_is_ca[i]) 318 continue; 319 if (key->cert == NULL || key->cert->signature_key == NULL) 320 return -1; /* shouldn't happen */ 321 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 322 continue; 323 if (sshkey_cert_check_host(key, hostname, 1, 324 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 325 debug_f("cert %s / hostname %s rejected: %s", 326 key->cert->key_id, hostname, reason); 327 continue; 328 } 329 return 0; 330 } 331 return -1; 332 } 333 334 /* Check destination constraints on an identity against the hostkey/user */ 335 static int 336 permitted_by_dest_constraints(const struct sshkey *fromkey, 337 const struct sshkey *tokey, Identity *id, const char *user, 338 const char **hostnamep) 339 { 340 size_t i; 341 struct dest_constraint *d; 342 343 if (hostnamep != NULL) 344 *hostnamep = NULL; 345 for (i = 0; i < id->ndest_constraints; i++) { 346 d = id->dest_constraints + i; 347 /* XXX remove logspam */ 348 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 349 i, d->from.user ? d->from.user : "", 350 d->from.user ? "@" : "", 351 d->from.hostname ? d->from.hostname : "(ORIGIN)", 352 d->from.nkeys, 353 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 354 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 355 356 /* Match 'from' key */ 357 if (fromkey == NULL) { 358 /* We are matching the first hop */ 359 if (d->from.hostname != NULL || d->from.nkeys != 0) 360 continue; 361 } else if (match_key_hop("from", fromkey, &d->from) != 0) 362 continue; 363 364 /* Match 'to' key */ 365 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 366 continue; 367 368 /* Match user if specified */ 369 if (d->to.user != NULL && user != NULL && 370 !match_pattern(user, d->to.user)) 371 continue; 372 373 /* successfully matched this constraint */ 374 if (hostnamep != NULL) 375 *hostnamep = d->to.hostname; 376 debug2_f("allowed for hostname %s", 377 d->to.hostname == NULL ? "*" : d->to.hostname); 378 return 0; 379 } 380 /* no match */ 381 debug2_f("%s identity \"%s\" not permitted for this destination", 382 sshkey_type(id->key), id->comment); 383 return -1; 384 } 385 386 /* 387 * Check whether hostkeys on a SocketEntry and the optionally specified user 388 * are permitted by the destination constraints on the Identity. 389 * Returns 0 on success or -1 otherwise. 390 */ 391 static int 392 identity_permitted(Identity *id, SocketEntry *e, char *user, 393 const char **forward_hostnamep, const char **last_hostnamep) 394 { 395 size_t i; 396 const char **hp; 397 struct hostkey_sid *hks; 398 const struct sshkey *fromkey = NULL; 399 const char *test_user; 400 char *fp1, *fp2; 401 402 /* XXX remove logspam */ 403 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 404 "%zu constraints", sshkey_type(id->key), id->comment, 405 e->nsession_ids, id->ndest_constraints); 406 if (id->ndest_constraints == 0) 407 return 0; /* unconstrained */ 408 if (e->nsession_ids == 0) 409 return 0; /* local use */ 410 /* 411 * Walk through the hops recorded by session_id and try to find a 412 * constraint that satisfies each. 413 */ 414 for (i = 0; i < e->nsession_ids; i++) { 415 hks = e->session_ids + i; 416 if (hks->key == NULL) 417 fatal_f("internal error: no bound key"); 418 /* XXX remove logspam */ 419 fp1 = fp2 = NULL; 420 if (fromkey != NULL && 421 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 422 SSH_FP_DEFAULT)) == NULL) 423 fatal_f("fingerprint failed"); 424 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 425 SSH_FP_DEFAULT)) == NULL) 426 fatal_f("fingerprint failed"); 427 debug3_f("socketentry fd=%d, entry %zu %s, " 428 "from hostkey %s %s to user %s hostkey %s %s", 429 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 430 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 431 fromkey ? fp1 : "", user ? user : "(ANY)", 432 sshkey_type(hks->key), fp2); 433 free(fp1); 434 free(fp2); 435 /* 436 * Record the hostnames for the initial forwarding and 437 * the final destination. 438 */ 439 hp = NULL; 440 if (i == e->nsession_ids - 1) 441 hp = last_hostnamep; 442 else if (i == 0) 443 hp = forward_hostnamep; 444 /* Special handling for final recorded binding */ 445 test_user = NULL; 446 if (i == e->nsession_ids - 1) { 447 /* Can only check user at final hop */ 448 test_user = user; 449 /* 450 * user is only presented for signature requests. 451 * If this is the case, make sure last binding is not 452 * for a forwarding. 453 */ 454 if (hks->forwarded && user != NULL) { 455 error_f("tried to sign on forwarding hop"); 456 return -1; 457 } 458 } else if (!hks->forwarded) { 459 error_f("tried to forward though signing bind"); 460 return -1; 461 } 462 if (permitted_by_dest_constraints(fromkey, hks->key, id, 463 test_user, hp) != 0) 464 return -1; 465 fromkey = hks->key; 466 } 467 /* 468 * Another special case: if the last bound session ID was for a 469 * forwarding, and this function is not being called to check a sign 470 * request (i.e. no 'user' supplied), then only permit the key if 471 * there is a permission that would allow it to be used at another 472 * destination. This hides keys that are allowed to be used to 473 * authenticate *to* a host but not permitted for *use* beyond it. 474 */ 475 hks = &e->session_ids[e->nsession_ids - 1]; 476 if (hks->forwarded && user == NULL && 477 permitted_by_dest_constraints(hks->key, NULL, id, 478 NULL, NULL) != 0) { 479 debug3_f("key permitted at host but not after"); 480 return -1; 481 } 482 483 /* success */ 484 return 0; 485 } 486 487 /* return matching private key for given public key */ 488 static Identity * 489 lookup_identity(struct sshkey *key) 490 { 491 Identity *id; 492 493 TAILQ_FOREACH(id, &idtab->idlist, next) { 494 if (sshkey_equal(key, id->key)) 495 return (id); 496 } 497 return (NULL); 498 } 499 500 /* Check confirmation of keysign request */ 501 static int 502 confirm_key(Identity *id, const char *extra) 503 { 504 char *p; 505 int ret = -1; 506 507 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 508 if (p != NULL && 509 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 510 id->comment, p, 511 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 512 ret = 0; 513 free(p); 514 515 return (ret); 516 } 517 518 static void 519 send_status(SocketEntry *e, int success) 520 { 521 int r; 522 523 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 524 (r = sshbuf_put_u8(e->output, success ? 525 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 526 fatal_fr(r, "compose"); 527 } 528 529 /* send list of supported public keys to 'client' */ 530 static void 531 process_request_identities(SocketEntry *e) 532 { 533 Identity *id; 534 struct sshbuf *msg, *keys; 535 int r; 536 u_int nentries = 0; 537 538 debug2_f("entering"); 539 540 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 541 fatal_f("sshbuf_new failed"); 542 TAILQ_FOREACH(id, &idtab->idlist, next) { 543 /* identity not visible, don't include in response */ 544 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 545 continue; 546 if ((r = sshkey_puts_opts(id->key, keys, 547 SSHKEY_SERIALIZE_INFO)) != 0 || 548 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 549 error_fr(r, "compose key/comment"); 550 continue; 551 } 552 nentries++; 553 } 554 debug2_f("replying with %u allowed of %u available keys", 555 nentries, idtab->nentries); 556 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 557 (r = sshbuf_put_u32(msg, nentries)) != 0 || 558 (r = sshbuf_putb(msg, keys)) != 0) 559 fatal_fr(r, "compose"); 560 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 561 fatal_fr(r, "enqueue"); 562 sshbuf_free(msg); 563 sshbuf_free(keys); 564 } 565 566 567 static char * 568 agent_decode_alg(struct sshkey *key, u_int flags) 569 { 570 if (key->type == KEY_RSA) { 571 if (flags & SSH_AGENT_RSA_SHA2_256) 572 return "rsa-sha2-256"; 573 else if (flags & SSH_AGENT_RSA_SHA2_512) 574 return "rsa-sha2-512"; 575 } else if (key->type == KEY_RSA_CERT) { 576 if (flags & SSH_AGENT_RSA_SHA2_256) 577 return "rsa-sha2-256-cert-v01@openssh.com"; 578 else if (flags & SSH_AGENT_RSA_SHA2_512) 579 return "rsa-sha2-512-cert-v01@openssh.com"; 580 } 581 return NULL; 582 } 583 584 /* 585 * Attempt to parse the contents of a buffer as a SSH publickey userauth 586 * request, checking its contents for consistency and matching the embedded 587 * key against the one that is being used for signing. 588 * Note: does not modify msg buffer. 589 * Optionally extract the username, session ID and/or hostkey from the request. 590 */ 591 static int 592 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 593 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 594 { 595 struct sshbuf *b = NULL, *sess_id = NULL; 596 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 597 int r; 598 u_char t, sig_follows; 599 struct sshkey *mkey = NULL, *hostkey = NULL; 600 601 if (userp != NULL) 602 *userp = NULL; 603 if (sess_idp != NULL) 604 *sess_idp = NULL; 605 if (hostkeyp != NULL) 606 *hostkeyp = NULL; 607 if ((b = sshbuf_fromb(msg)) == NULL) 608 fatal_f("sshbuf_fromb"); 609 610 /* SSH userauth request */ 611 if ((r = sshbuf_froms(b, &sess_id)) != 0) 612 goto out; 613 if (sshbuf_len(sess_id) == 0) { 614 r = SSH_ERR_INVALID_FORMAT; 615 goto out; 616 } 617 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 618 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 619 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 620 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 621 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 622 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 623 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 624 goto out; 625 if (t != SSH2_MSG_USERAUTH_REQUEST || 626 sig_follows != 1 || 627 strcmp(service, "ssh-connection") != 0 || 628 !sshkey_equal(expected_key, mkey) || 629 sshkey_type_from_name(pkalg) != expected_key->type) { 630 r = SSH_ERR_INVALID_FORMAT; 631 goto out; 632 } 633 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 634 if ((r = sshkey_froms(b, &hostkey)) != 0) 635 goto out; 636 } else if (strcmp(method, "publickey") != 0) { 637 r = SSH_ERR_INVALID_FORMAT; 638 goto out; 639 } 640 if (sshbuf_len(b) != 0) { 641 r = SSH_ERR_INVALID_FORMAT; 642 goto out; 643 } 644 /* success */ 645 r = 0; 646 debug3_f("well formed userauth"); 647 if (userp != NULL) { 648 *userp = user; 649 user = NULL; 650 } 651 if (sess_idp != NULL) { 652 *sess_idp = sess_id; 653 sess_id = NULL; 654 } 655 if (hostkeyp != NULL) { 656 *hostkeyp = hostkey; 657 hostkey = NULL; 658 } 659 out: 660 sshbuf_free(b); 661 sshbuf_free(sess_id); 662 free(user); 663 free(service); 664 free(method); 665 free(pkalg); 666 sshkey_free(mkey); 667 sshkey_free(hostkey); 668 return r; 669 } 670 671 /* 672 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 673 * Note: does not modify buffer. 674 */ 675 static int 676 parse_sshsig_request(struct sshbuf *msg) 677 { 678 int r; 679 struct sshbuf *b; 680 681 if ((b = sshbuf_fromb(msg)) == NULL) 682 fatal_f("sshbuf_fromb"); 683 684 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 685 (r = sshbuf_consume(b, 6)) != 0 || 686 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 687 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 688 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 689 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 690 goto out; 691 if (sshbuf_len(b) != 0) { 692 r = SSH_ERR_INVALID_FORMAT; 693 goto out; 694 } 695 /* success */ 696 r = 0; 697 out: 698 sshbuf_free(b); 699 return r; 700 } 701 702 /* 703 * This function inspects a message to be signed by a FIDO key that has a 704 * web-like application string (i.e. one that does not begin with "ssh:". 705 * It checks that the message is one of those expected for SSH operations 706 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 707 * for the web. 708 */ 709 static int 710 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 711 { 712 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 713 debug_f("signed data matches public key userauth request"); 714 return 1; 715 } 716 if (parse_sshsig_request(data) == 0) { 717 debug_f("signed data matches SSHSIG signature request"); 718 return 1; 719 } 720 721 /* XXX check CA signature operation */ 722 723 error("web-origin key attempting to sign non-SSH message"); 724 return 0; 725 } 726 727 static int 728 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 729 { 730 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 731 return SSH_ERR_INVALID_ARGUMENT; 732 if (sshbuf_len(a) != sshbuf_len(b)) 733 return SSH_ERR_INVALID_FORMAT; 734 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 735 return SSH_ERR_INVALID_FORMAT; 736 return 0; 737 } 738 739 /* ssh2 only */ 740 static void 741 process_sign_request2(SocketEntry *e) 742 { 743 u_char *signature = NULL; 744 size_t slen = 0; 745 u_int compat = 0, flags; 746 int r, ok = -1, retried = 0; 747 char *fp = NULL, *pin = NULL, *prompt = NULL; 748 char *user = NULL, *sig_dest = NULL; 749 const char *fwd_host = NULL, *dest_host = NULL; 750 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 751 struct sshkey *key = NULL, *hostkey = NULL; 752 struct identity *id; 753 struct notifier_ctx *notifier = NULL; 754 755 debug_f("entering"); 756 757 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 758 fatal_f("sshbuf_new failed"); 759 if ((r = sshkey_froms(e->request, &key)) != 0 || 760 (r = sshbuf_get_stringb(e->request, data)) != 0 || 761 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 762 error_fr(r, "parse"); 763 goto send; 764 } 765 766 if ((id = lookup_identity(key)) == NULL) { 767 verbose_f("%s key not found", sshkey_type(key)); 768 goto send; 769 } 770 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 771 SSH_FP_DEFAULT)) == NULL) 772 fatal_f("fingerprint failed"); 773 774 if (id->ndest_constraints != 0) { 775 if (e->nsession_ids == 0) { 776 logit_f("refusing use of destination-constrained key " 777 "to sign on unbound connection"); 778 goto send; 779 } 780 if (parse_userauth_request(data, key, &user, &sid, 781 &hostkey) != 0) { 782 logit_f("refusing use of destination-constrained key " 783 "to sign an unidentified signature"); 784 goto send; 785 } 786 /* XXX logspam */ 787 debug_f("user=%s", user); 788 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 789 goto send; 790 /* XXX display fwd_host/dest_host in askpass UI */ 791 /* 792 * Ensure that the session ID is the most recent one 793 * registered on the socket - it should have been bound by 794 * ssh immediately before userauth. 795 */ 796 if (buf_equal(sid, 797 e->session_ids[e->nsession_ids - 1].sid) != 0) { 798 error_f("unexpected session ID (%zu listed) on " 799 "signature request for target user %s with " 800 "key %s %s", e->nsession_ids, user, 801 sshkey_type(id->key), fp); 802 goto send; 803 } 804 /* 805 * Ensure that the hostkey embedded in the signature matches 806 * the one most recently bound to the socket. An exception is 807 * made for the initial forwarding hop. 808 */ 809 if (e->nsession_ids > 1 && hostkey == NULL) { 810 error_f("refusing use of destination-constrained key: " 811 "no hostkey recorded in signature for forwarded " 812 "connection"); 813 goto send; 814 } 815 if (hostkey != NULL && !sshkey_equal(hostkey, 816 e->session_ids[e->nsession_ids - 1].key)) { 817 error_f("refusing use of destination-constrained key: " 818 "mismatch between hostkey in request and most " 819 "recently bound session"); 820 goto send; 821 } 822 xasprintf(&sig_dest, "public key authentication request for " 823 "user \"%s\" to listed host", user); 824 } 825 if (id->confirm && confirm_key(id, sig_dest) != 0) { 826 verbose_f("user refused key"); 827 goto send; 828 } 829 if (sshkey_is_sk(id->key)) { 830 if (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_VERIFICATION_REQD)) { 836 /* XXX include sig_dest */ 837 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 838 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 839 " and confirm user presence " : " ", 840 sshkey_type(id->key), fp); 841 pin = read_passphrase(prompt, RP_USE_ASKPASS); 842 free(prompt); 843 prompt = NULL; 844 } else if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 845 notifier = notify_start(0, 846 "Confirm user presence for key %s %s%s%s", 847 sshkey_type(id->key), fp, 848 sig_dest == NULL ? "" : "\n", 849 sig_dest == NULL ? "" : sig_dest); 850 } 851 } 852 retry_pin: 853 if ((r = sshkey_sign(id->key, &signature, &slen, 854 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 855 id->sk_provider, pin, compat)) != 0) { 856 debug_fr(r, "sshkey_sign"); 857 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 858 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 859 if (notifier) { 860 notify_complete(notifier, NULL); 861 notifier = NULL; 862 } 863 /* XXX include sig_dest */ 864 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 865 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 866 " and confirm user presence " : " ", 867 sshkey_type(id->key), fp); 868 pin = read_passphrase(prompt, RP_USE_ASKPASS); 869 retried = 1; 870 goto retry_pin; 871 } 872 error_fr(r, "sshkey_sign"); 873 goto send; 874 } 875 /* Success */ 876 ok = 0; 877 send: 878 notify_complete(notifier, "User presence confirmed"); 879 880 if (ok == 0) { 881 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 882 (r = sshbuf_put_string(msg, signature, slen)) != 0) 883 fatal_fr(r, "compose"); 884 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 885 fatal_fr(r, "compose failure"); 886 887 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 888 fatal_fr(r, "enqueue"); 889 890 sshbuf_free(sid); 891 sshbuf_free(data); 892 sshbuf_free(msg); 893 sshkey_free(key); 894 sshkey_free(hostkey); 895 free(fp); 896 free(signature); 897 free(sig_dest); 898 free(user); 899 free(prompt); 900 if (pin != NULL) 901 freezero(pin, strlen(pin)); 902 } 903 904 /* shared */ 905 static void 906 process_remove_identity(SocketEntry *e) 907 { 908 int r, success = 0; 909 struct sshkey *key = NULL; 910 Identity *id; 911 912 debug2_f("entering"); 913 if ((r = sshkey_froms(e->request, &key)) != 0) { 914 error_fr(r, "parse key"); 915 goto done; 916 } 917 if ((id = lookup_identity(key)) == NULL) { 918 debug_f("key not found"); 919 goto done; 920 } 921 /* identity not visible, cannot be removed */ 922 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 923 goto done; /* error already logged */ 924 /* We have this key, free it. */ 925 if (idtab->nentries < 1) 926 fatal_f("internal error: nentries %d", idtab->nentries); 927 TAILQ_REMOVE(&idtab->idlist, id, next); 928 free_identity(id); 929 idtab->nentries--; 930 success = 1; 931 done: 932 sshkey_free(key); 933 send_status(e, success); 934 } 935 936 static void 937 process_remove_all_identities(SocketEntry *e) 938 { 939 Identity *id; 940 941 debug2_f("entering"); 942 /* Loop over all identities and clear the keys. */ 943 for (id = TAILQ_FIRST(&idtab->idlist); id; 944 id = TAILQ_FIRST(&idtab->idlist)) { 945 TAILQ_REMOVE(&idtab->idlist, id, next); 946 free_identity(id); 947 } 948 949 /* Mark that there are no identities. */ 950 idtab->nentries = 0; 951 952 /* Send success. */ 953 send_status(e, 1); 954 } 955 956 /* removes expired keys and returns number of seconds until the next expiry */ 957 static time_t 958 reaper(void) 959 { 960 time_t deadline = 0, now = monotime(); 961 Identity *id, *nxt; 962 963 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 964 nxt = TAILQ_NEXT(id, next); 965 if (id->death == 0) 966 continue; 967 if (now >= id->death) { 968 debug("expiring key '%s'", id->comment); 969 TAILQ_REMOVE(&idtab->idlist, id, next); 970 free_identity(id); 971 idtab->nentries--; 972 } else 973 deadline = (deadline == 0) ? id->death : 974 MINIMUM(deadline, id->death); 975 } 976 if (deadline == 0 || deadline <= now) 977 return 0; 978 else 979 return (deadline - now); 980 } 981 982 static int 983 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 984 { 985 u_char key_is_ca; 986 size_t elen = 0; 987 int r; 988 struct sshkey *k = NULL; 989 char *fp; 990 991 memset(dch, '\0', sizeof(*dch)); 992 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 993 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 994 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 995 error_fr(r, "parse"); 996 goto out; 997 } 998 if (elen != 0) { 999 error_f("unsupported extensions (len %zu)", elen); 1000 r = SSH_ERR_FEATURE_UNSUPPORTED; 1001 goto out; 1002 } 1003 if (*dch->hostname == '\0') { 1004 free(dch->hostname); 1005 dch->hostname = NULL; 1006 } 1007 if (*dch->user == '\0') { 1008 free(dch->user); 1009 dch->user = NULL; 1010 } 1011 while (sshbuf_len(b) != 0) { 1012 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1013 dch->nkeys + 1, sizeof(*dch->keys)); 1014 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1015 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1016 if ((r = sshkey_froms(b, &k)) != 0 || 1017 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1018 goto out; 1019 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1020 SSH_FP_DEFAULT)) == NULL) 1021 fatal_f("fingerprint failed"); 1022 debug3_f("%s%s%s: adding %skey %s %s", 1023 dch->user == NULL ? "" : dch->user, 1024 dch->user == NULL ? "" : "@", 1025 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1026 free(fp); 1027 dch->keys[dch->nkeys] = k; 1028 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1029 dch->nkeys++; 1030 k = NULL; /* transferred */ 1031 } 1032 /* success */ 1033 r = 0; 1034 out: 1035 sshkey_free(k); 1036 return r; 1037 } 1038 1039 static int 1040 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1041 { 1042 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1043 int r; 1044 size_t elen = 0; 1045 1046 debug3_f("entering"); 1047 1048 memset(dc, '\0', sizeof(*dc)); 1049 if ((r = sshbuf_froms(m, &b)) != 0 || 1050 (r = sshbuf_froms(b, &frombuf)) != 0 || 1051 (r = sshbuf_froms(b, &tobuf)) != 0 || 1052 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1053 error_fr(r, "parse"); 1054 goto out; 1055 } 1056 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1057 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1058 goto out; /* already logged */ 1059 if (elen != 0) { 1060 error_f("unsupported extensions (len %zu)", elen); 1061 r = SSH_ERR_FEATURE_UNSUPPORTED; 1062 goto out; 1063 } 1064 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1065 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1066 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1067 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1068 /* check consistency */ 1069 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1070 dc->from.user != NULL) { 1071 error_f("inconsistent \"from\" specification"); 1072 r = SSH_ERR_INVALID_FORMAT; 1073 goto out; 1074 } 1075 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1076 error_f("incomplete \"to\" specification"); 1077 r = SSH_ERR_INVALID_FORMAT; 1078 goto out; 1079 } 1080 /* success */ 1081 r = 0; 1082 out: 1083 sshbuf_free(b); 1084 sshbuf_free(frombuf); 1085 sshbuf_free(tobuf); 1086 return r; 1087 } 1088 1089 static int 1090 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1091 struct dest_constraint **dcsp, size_t *ndcsp) 1092 { 1093 char *ext_name = NULL; 1094 int r; 1095 struct sshbuf *b = NULL; 1096 1097 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1098 error_fr(r, "parse constraint extension"); 1099 goto out; 1100 } 1101 debug_f("constraint ext %s", ext_name); 1102 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1103 if (sk_providerp == NULL) { 1104 error_f("%s not valid here", ext_name); 1105 r = SSH_ERR_INVALID_FORMAT; 1106 goto out; 1107 } 1108 if (*sk_providerp != NULL) { 1109 error_f("%s already set", ext_name); 1110 r = SSH_ERR_INVALID_FORMAT; 1111 goto out; 1112 } 1113 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1114 error_fr(r, "parse %s", ext_name); 1115 goto out; 1116 } 1117 } else if (strcmp(ext_name, 1118 "restrict-destination-v00@openssh.com") == 0) { 1119 if (*dcsp != NULL) { 1120 error_f("%s already set", ext_name); 1121 goto out; 1122 } 1123 if ((r = sshbuf_froms(m, &b)) != 0) { 1124 error_fr(r, "parse %s outer", ext_name); 1125 goto out; 1126 } 1127 while (sshbuf_len(b) != 0) { 1128 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1129 error_f("too many %s constraints", ext_name); 1130 goto out; 1131 } 1132 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1133 sizeof(**dcsp)); 1134 if ((r = parse_dest_constraint(b, 1135 *dcsp + (*ndcsp)++)) != 0) 1136 goto out; /* error already logged */ 1137 } 1138 } else { 1139 error_f("unsupported constraint \"%s\"", ext_name); 1140 r = SSH_ERR_FEATURE_UNSUPPORTED; 1141 goto out; 1142 } 1143 /* success */ 1144 r = 0; 1145 out: 1146 free(ext_name); 1147 sshbuf_free(b); 1148 return r; 1149 } 1150 1151 static int 1152 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1153 u_int *secondsp, int *confirmp, char **sk_providerp, 1154 struct dest_constraint **dcsp, size_t *ndcsp) 1155 { 1156 u_char ctype; 1157 int r; 1158 u_int seconds, maxsign = 0; 1159 1160 while (sshbuf_len(m)) { 1161 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1162 error_fr(r, "parse constraint type"); 1163 goto out; 1164 } 1165 switch (ctype) { 1166 case SSH_AGENT_CONSTRAIN_LIFETIME: 1167 if (*deathp != 0) { 1168 error_f("lifetime already set"); 1169 r = SSH_ERR_INVALID_FORMAT; 1170 goto out; 1171 } 1172 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1173 error_fr(r, "parse lifetime constraint"); 1174 goto out; 1175 } 1176 *deathp = monotime() + seconds; 1177 *secondsp = seconds; 1178 break; 1179 case SSH_AGENT_CONSTRAIN_CONFIRM: 1180 if (*confirmp != 0) { 1181 error_f("confirm already set"); 1182 r = SSH_ERR_INVALID_FORMAT; 1183 goto out; 1184 } 1185 *confirmp = 1; 1186 break; 1187 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1188 if (k == NULL) { 1189 error_f("maxsign not valid here"); 1190 r = SSH_ERR_INVALID_FORMAT; 1191 goto out; 1192 } 1193 if (maxsign != 0) { 1194 error_f("maxsign already set"); 1195 r = SSH_ERR_INVALID_FORMAT; 1196 goto out; 1197 } 1198 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1199 error_fr(r, "parse maxsign constraint"); 1200 goto out; 1201 } 1202 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1203 error_fr(r, "enable maxsign"); 1204 goto out; 1205 } 1206 break; 1207 case SSH_AGENT_CONSTRAIN_EXTENSION: 1208 if ((r = parse_key_constraint_extension(m, 1209 sk_providerp, dcsp, ndcsp)) != 0) 1210 goto out; /* error already logged */ 1211 break; 1212 default: 1213 error_f("Unknown constraint %d", ctype); 1214 r = SSH_ERR_FEATURE_UNSUPPORTED; 1215 goto out; 1216 } 1217 } 1218 /* success */ 1219 r = 0; 1220 out: 1221 return r; 1222 } 1223 1224 static void 1225 process_add_identity(SocketEntry *e) 1226 { 1227 Identity *id; 1228 int success = 0, confirm = 0; 1229 char *fp, *comment = NULL, *sk_provider = NULL; 1230 char canonical_provider[PATH_MAX]; 1231 time_t death = 0; 1232 u_int seconds = 0; 1233 struct dest_constraint *dest_constraints = NULL; 1234 size_t ndest_constraints = 0; 1235 struct sshkey *k = NULL; 1236 int r = SSH_ERR_INTERNAL_ERROR; 1237 1238 debug2_f("entering"); 1239 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1240 k == NULL || 1241 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1242 error_fr(r, "parse"); 1243 goto out; 1244 } 1245 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1246 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1247 error_f("failed to parse constraints"); 1248 sshbuf_reset(e->request); 1249 goto out; 1250 } 1251 1252 if (sk_provider != NULL) { 1253 if (!sshkey_is_sk(k)) { 1254 error("Cannot add provider: %s is not an " 1255 "authenticator-hosted key", sshkey_type(k)); 1256 goto out; 1257 } 1258 if (strcasecmp(sk_provider, "internal") == 0) { 1259 debug_f("internal provider"); 1260 } else { 1261 if (realpath(sk_provider, canonical_provider) == NULL) { 1262 verbose("failed provider \"%.100s\": " 1263 "realpath: %s", sk_provider, 1264 strerror(errno)); 1265 goto out; 1266 } 1267 free(sk_provider); 1268 sk_provider = xstrdup(canonical_provider); 1269 if (match_pattern_list(sk_provider, 1270 allowed_providers, 0) != 1) { 1271 error("Refusing add key: " 1272 "provider %s not allowed", sk_provider); 1273 goto out; 1274 } 1275 } 1276 } 1277 if ((r = sshkey_shield_private(k)) != 0) { 1278 error_fr(r, "shield private"); 1279 goto out; 1280 } 1281 if (lifetime && !death) 1282 death = monotime() + lifetime; 1283 if ((id = lookup_identity(k)) == NULL) { 1284 id = xcalloc(1, sizeof(Identity)); 1285 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1286 /* Increment the number of identities. */ 1287 idtab->nentries++; 1288 } else { 1289 /* identity not visible, do not update */ 1290 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1291 goto out; /* error already logged */ 1292 /* key state might have been updated */ 1293 sshkey_free(id->key); 1294 free(id->comment); 1295 free(id->sk_provider); 1296 free_dest_constraints(id->dest_constraints, 1297 id->ndest_constraints); 1298 } 1299 /* success */ 1300 id->key = k; 1301 id->comment = comment; 1302 id->death = death; 1303 id->confirm = confirm; 1304 id->sk_provider = sk_provider; 1305 id->dest_constraints = dest_constraints; 1306 id->ndest_constraints = ndest_constraints; 1307 1308 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1309 SSH_FP_DEFAULT)) == NULL) 1310 fatal_f("sshkey_fingerprint failed"); 1311 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1312 "(provider: %s) (destination constraints: %zu)", 1313 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1314 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1315 free(fp); 1316 /* transferred */ 1317 k = NULL; 1318 comment = NULL; 1319 sk_provider = NULL; 1320 dest_constraints = NULL; 1321 ndest_constraints = 0; 1322 success = 1; 1323 out: 1324 free(sk_provider); 1325 free(comment); 1326 sshkey_free(k); 1327 free_dest_constraints(dest_constraints, ndest_constraints); 1328 send_status(e, success); 1329 } 1330 1331 /* XXX todo: encrypt sensitive data with passphrase */ 1332 static void 1333 process_lock_agent(SocketEntry *e, int lock) 1334 { 1335 int r, success = 0, delay; 1336 char *passwd; 1337 u_char passwdhash[LOCK_SIZE]; 1338 static u_int fail_count = 0; 1339 size_t pwlen; 1340 1341 debug2_f("entering"); 1342 /* 1343 * This is deliberately fatal: the user has requested that we lock, 1344 * but we can't parse their request properly. The only safe thing to 1345 * do is abort. 1346 */ 1347 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1348 fatal_fr(r, "parse"); 1349 if (pwlen == 0) { 1350 debug("empty password not supported"); 1351 } else if (locked && !lock) { 1352 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1353 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1354 fatal("bcrypt_pbkdf"); 1355 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1356 debug("agent unlocked"); 1357 locked = 0; 1358 fail_count = 0; 1359 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1360 success = 1; 1361 } else { 1362 /* delay in 0.1s increments up to 10s */ 1363 if (fail_count < 100) 1364 fail_count++; 1365 delay = 100000 * fail_count; 1366 debug("unlock failed, delaying %0.1lf seconds", 1367 (double)delay/1000000); 1368 usleep(delay); 1369 } 1370 explicit_bzero(passwdhash, sizeof(passwdhash)); 1371 } else if (!locked && lock) { 1372 debug("agent locked"); 1373 locked = 1; 1374 arc4random_buf(lock_salt, sizeof(lock_salt)); 1375 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1376 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1377 fatal("bcrypt_pbkdf"); 1378 success = 1; 1379 } 1380 freezero(passwd, pwlen); 1381 send_status(e, success); 1382 } 1383 1384 static void 1385 no_identities(SocketEntry *e) 1386 { 1387 struct sshbuf *msg; 1388 int r; 1389 1390 if ((msg = sshbuf_new()) == NULL) 1391 fatal_f("sshbuf_new failed"); 1392 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1393 (r = sshbuf_put_u32(msg, 0)) != 0 || 1394 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1395 fatal_fr(r, "compose"); 1396 sshbuf_free(msg); 1397 } 1398 1399 #ifdef ENABLE_PKCS11 1400 static void 1401 process_add_smartcard_key(SocketEntry *e) 1402 { 1403 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1404 char **comments = NULL; 1405 int r, i, count = 0, success = 0, confirm = 0; 1406 u_int seconds = 0; 1407 time_t death = 0; 1408 struct sshkey **keys = NULL, *k; 1409 Identity *id; 1410 struct dest_constraint *dest_constraints = NULL; 1411 size_t ndest_constraints = 0; 1412 1413 debug2_f("entering"); 1414 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1415 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1416 error_fr(r, "parse"); 1417 goto send; 1418 } 1419 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1420 NULL, &dest_constraints, &ndest_constraints) != 0) { 1421 error_f("failed to parse constraints"); 1422 goto send; 1423 } 1424 if (realpath(provider, canonical_provider) == NULL) { 1425 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1426 provider, strerror(errno)); 1427 goto send; 1428 } 1429 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1430 verbose("refusing PKCS#11 add of \"%.100s\": " 1431 "provider not allowed", canonical_provider); 1432 goto send; 1433 } 1434 debug_f("add %.100s", canonical_provider); 1435 if (lifetime && !death) 1436 death = monotime() + lifetime; 1437 1438 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1439 for (i = 0; i < count; i++) { 1440 k = keys[i]; 1441 if (lookup_identity(k) == NULL) { 1442 id = xcalloc(1, sizeof(Identity)); 1443 id->key = k; 1444 keys[i] = NULL; /* transferred */ 1445 id->provider = xstrdup(canonical_provider); 1446 if (*comments[i] != '\0') { 1447 id->comment = comments[i]; 1448 comments[i] = NULL; /* transferred */ 1449 } else { 1450 id->comment = xstrdup(canonical_provider); 1451 } 1452 id->death = death; 1453 id->confirm = confirm; 1454 id->dest_constraints = dest_constraints; 1455 id->ndest_constraints = ndest_constraints; 1456 dest_constraints = NULL; /* transferred */ 1457 ndest_constraints = 0; 1458 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1459 idtab->nentries++; 1460 success = 1; 1461 } 1462 /* XXX update constraints for existing keys */ 1463 sshkey_free(keys[i]); 1464 free(comments[i]); 1465 } 1466 send: 1467 free(pin); 1468 free(provider); 1469 free(keys); 1470 free(comments); 1471 free_dest_constraints(dest_constraints, ndest_constraints); 1472 send_status(e, success); 1473 } 1474 1475 static void 1476 process_remove_smartcard_key(SocketEntry *e) 1477 { 1478 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1479 int r, success = 0; 1480 Identity *id, *nxt; 1481 1482 debug2_f("entering"); 1483 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1484 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1485 error_fr(r, "parse"); 1486 goto send; 1487 } 1488 free(pin); 1489 1490 if (realpath(provider, canonical_provider) == NULL) { 1491 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1492 provider, strerror(errno)); 1493 goto send; 1494 } 1495 1496 debug_f("remove %.100s", canonical_provider); 1497 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1498 nxt = TAILQ_NEXT(id, next); 1499 /* Skip file--based keys */ 1500 if (id->provider == NULL) 1501 continue; 1502 if (!strcmp(canonical_provider, id->provider)) { 1503 TAILQ_REMOVE(&idtab->idlist, id, next); 1504 free_identity(id); 1505 idtab->nentries--; 1506 } 1507 } 1508 if (pkcs11_del_provider(canonical_provider) == 0) 1509 success = 1; 1510 else 1511 error_f("pkcs11_del_provider failed"); 1512 send: 1513 free(provider); 1514 send_status(e, success); 1515 } 1516 #endif /* ENABLE_PKCS11 */ 1517 1518 static int 1519 process_ext_session_bind(SocketEntry *e) 1520 { 1521 int r, sid_match, key_match; 1522 struct sshkey *key = NULL; 1523 struct sshbuf *sid = NULL, *sig = NULL; 1524 char *fp = NULL; 1525 size_t i; 1526 u_char fwd = 0; 1527 1528 debug2_f("entering"); 1529 if ((r = sshkey_froms(e->request, &key)) != 0 || 1530 (r = sshbuf_froms(e->request, &sid)) != 0 || 1531 (r = sshbuf_froms(e->request, &sig)) != 0 || 1532 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1533 error_fr(r, "parse"); 1534 goto out; 1535 } 1536 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1537 SSH_FP_DEFAULT)) == NULL) 1538 fatal_f("fingerprint failed"); 1539 /* check signature with hostkey on session ID */ 1540 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1541 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1542 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1543 goto out; 1544 } 1545 /* check whether sid/key already recorded */ 1546 for (i = 0; i < e->nsession_ids; i++) { 1547 if (!e->session_ids[i].forwarded) { 1548 error_f("attempt to bind session ID to socket " 1549 "previously bound for authentication attempt"); 1550 r = -1; 1551 goto out; 1552 } 1553 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1554 key_match = sshkey_equal(key, e->session_ids[i].key); 1555 if (sid_match && key_match) { 1556 debug_f("session ID already recorded for %s %s", 1557 sshkey_type(key), fp); 1558 r = 0; 1559 goto out; 1560 } else if (sid_match) { 1561 error_f("session ID recorded against different key " 1562 "for %s %s", sshkey_type(key), fp); 1563 r = -1; 1564 goto out; 1565 } 1566 /* 1567 * new sid with previously-seen key can happen, e.g. multiple 1568 * connections to the same host. 1569 */ 1570 } 1571 /* record new key/sid */ 1572 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1573 error_f("too many session IDs recorded"); 1574 goto out; 1575 } 1576 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1577 e->nsession_ids + 1, sizeof(*e->session_ids)); 1578 i = e->nsession_ids++; 1579 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1580 AGENT_MAX_SESSION_IDS); 1581 e->session_ids[i].key = key; 1582 e->session_ids[i].forwarded = fwd != 0; 1583 key = NULL; /* transferred */ 1584 /* can't transfer sid; it's refcounted and scoped to request's life */ 1585 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1586 fatal_f("sshbuf_new"); 1587 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1588 fatal_fr(r, "sshbuf_putb session ID"); 1589 /* success */ 1590 r = 0; 1591 out: 1592 sshkey_free(key); 1593 sshbuf_free(sid); 1594 sshbuf_free(sig); 1595 return r == 0 ? 1 : 0; 1596 } 1597 1598 static void 1599 process_extension(SocketEntry *e) 1600 { 1601 int r, success = 0; 1602 char *name; 1603 1604 debug2_f("entering"); 1605 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1606 error_fr(r, "parse"); 1607 goto send; 1608 } 1609 if (strcmp(name, "session-bind@openssh.com") == 0) 1610 success = process_ext_session_bind(e); 1611 else 1612 debug_f("unsupported extension \"%s\"", name); 1613 free(name); 1614 send: 1615 send_status(e, success); 1616 } 1617 /* 1618 * dispatch incoming message. 1619 * returns 1 on success, 0 for incomplete messages or -1 on error. 1620 */ 1621 static int 1622 process_message(u_int socknum) 1623 { 1624 u_int msg_len; 1625 u_char type; 1626 const u_char *cp; 1627 int r; 1628 SocketEntry *e; 1629 1630 if (socknum >= sockets_alloc) 1631 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1632 e = &sockets[socknum]; 1633 1634 if (sshbuf_len(e->input) < 5) 1635 return 0; /* Incomplete message header. */ 1636 cp = sshbuf_ptr(e->input); 1637 msg_len = PEEK_U32(cp); 1638 if (msg_len > AGENT_MAX_LEN) { 1639 debug_f("socket %u (fd=%d) message too long %u > %u", 1640 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1641 return -1; 1642 } 1643 if (sshbuf_len(e->input) < msg_len + 4) 1644 return 0; /* Incomplete message body. */ 1645 1646 /* move the current input to e->request */ 1647 sshbuf_reset(e->request); 1648 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1649 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1650 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1651 r == SSH_ERR_STRING_TOO_LARGE) { 1652 error_fr(r, "parse"); 1653 return -1; 1654 } 1655 fatal_fr(r, "parse"); 1656 } 1657 1658 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1659 1660 /* check whether agent is locked */ 1661 if (locked && type != SSH_AGENTC_UNLOCK) { 1662 sshbuf_reset(e->request); 1663 switch (type) { 1664 case SSH2_AGENTC_REQUEST_IDENTITIES: 1665 /* send empty lists */ 1666 no_identities(e); 1667 break; 1668 default: 1669 /* send a fail message for all other request types */ 1670 send_status(e, 0); 1671 } 1672 return 1; 1673 } 1674 1675 switch (type) { 1676 case SSH_AGENTC_LOCK: 1677 case SSH_AGENTC_UNLOCK: 1678 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1679 break; 1680 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1681 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1682 break; 1683 /* ssh2 */ 1684 case SSH2_AGENTC_SIGN_REQUEST: 1685 process_sign_request2(e); 1686 break; 1687 case SSH2_AGENTC_REQUEST_IDENTITIES: 1688 process_request_identities(e); 1689 break; 1690 case SSH2_AGENTC_ADD_IDENTITY: 1691 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1692 process_add_identity(e); 1693 break; 1694 case SSH2_AGENTC_REMOVE_IDENTITY: 1695 process_remove_identity(e); 1696 break; 1697 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1698 process_remove_all_identities(e); 1699 break; 1700 #ifdef ENABLE_PKCS11 1701 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1702 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1703 process_add_smartcard_key(e); 1704 break; 1705 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1706 process_remove_smartcard_key(e); 1707 break; 1708 #endif /* ENABLE_PKCS11 */ 1709 case SSH_AGENTC_EXTENSION: 1710 process_extension(e); 1711 break; 1712 default: 1713 /* Unknown message. Respond with failure. */ 1714 error("Unknown message %d", type); 1715 sshbuf_reset(e->request); 1716 send_status(e, 0); 1717 break; 1718 } 1719 return 1; 1720 } 1721 1722 static void 1723 new_socket(sock_type type, int fd) 1724 { 1725 u_int i, old_alloc, new_alloc; 1726 1727 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1728 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1729 if (type == AUTH_CONNECTION) { 1730 debug("xcount %d -> %d", xcount, xcount + 1); 1731 ++xcount; 1732 } 1733 set_nonblock(fd); 1734 1735 if (fd > max_fd) 1736 max_fd = fd; 1737 1738 for (i = 0; i < sockets_alloc; i++) 1739 if (sockets[i].type == AUTH_UNUSED) { 1740 sockets[i].fd = fd; 1741 if ((sockets[i].input = sshbuf_new()) == NULL || 1742 (sockets[i].output = sshbuf_new()) == NULL || 1743 (sockets[i].request = sshbuf_new()) == NULL) 1744 fatal_f("sshbuf_new failed"); 1745 sockets[i].type = type; 1746 return; 1747 } 1748 old_alloc = sockets_alloc; 1749 new_alloc = sockets_alloc + 10; 1750 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1751 sizeof(sockets[0])); 1752 for (i = old_alloc; i < new_alloc; i++) 1753 sockets[i].type = AUTH_UNUSED; 1754 sockets_alloc = new_alloc; 1755 sockets[old_alloc].fd = fd; 1756 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1757 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1758 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1759 fatal_f("sshbuf_new failed"); 1760 sockets[old_alloc].type = type; 1761 } 1762 1763 static int 1764 handle_socket_read(u_int socknum) 1765 { 1766 struct sockaddr_un sunaddr; 1767 socklen_t slen; 1768 uid_t euid; 1769 gid_t egid; 1770 int fd; 1771 1772 slen = sizeof(sunaddr); 1773 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1774 if (fd == -1) { 1775 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1776 return -1; 1777 } 1778 if (getpeereid(fd, &euid, &egid) == -1) { 1779 error("getpeereid %d failed: %s", fd, strerror(errno)); 1780 close(fd); 1781 return -1; 1782 } 1783 if ((euid != 0) && (getuid() != euid)) { 1784 error("uid mismatch: peer euid %u != uid %u", 1785 (u_int) euid, (u_int) getuid()); 1786 close(fd); 1787 return -1; 1788 } 1789 new_socket(AUTH_CONNECTION, fd); 1790 return 0; 1791 } 1792 1793 static int 1794 handle_conn_read(u_int socknum) 1795 { 1796 char buf[AGENT_RBUF_LEN]; 1797 ssize_t len; 1798 int r; 1799 1800 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1801 if (len == -1) { 1802 if (errno == EAGAIN || errno == EINTR) 1803 return 0; 1804 error_f("read error on socket %u (fd %d): %s", 1805 socknum, sockets[socknum].fd, strerror(errno)); 1806 } 1807 return -1; 1808 } 1809 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1810 fatal_fr(r, "compose"); 1811 explicit_bzero(buf, sizeof(buf)); 1812 for (;;) { 1813 if ((r = process_message(socknum)) == -1) 1814 return -1; 1815 else if (r == 0) 1816 break; 1817 } 1818 return 0; 1819 } 1820 1821 static int 1822 handle_conn_write(u_int socknum) 1823 { 1824 ssize_t len; 1825 int r; 1826 1827 if (sshbuf_len(sockets[socknum].output) == 0) 1828 return 0; /* shouldn't happen */ 1829 if ((len = write(sockets[socknum].fd, 1830 sshbuf_ptr(sockets[socknum].output), 1831 sshbuf_len(sockets[socknum].output))) <= 0) { 1832 if (len == -1) { 1833 if (errno == EAGAIN || errno == EINTR) 1834 return 0; 1835 error_f("read error on socket %u (fd %d): %s", 1836 socknum, sockets[socknum].fd, strerror(errno)); 1837 } 1838 return -1; 1839 } 1840 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1841 fatal_fr(r, "consume"); 1842 return 0; 1843 } 1844 1845 static void 1846 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1847 { 1848 size_t i; 1849 u_int socknum, activefds = npfd; 1850 1851 for (i = 0; i < npfd; i++) { 1852 if (pfd[i].revents == 0) 1853 continue; 1854 /* Find sockets entry */ 1855 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1856 if (sockets[socknum].type != AUTH_SOCKET && 1857 sockets[socknum].type != AUTH_CONNECTION) 1858 continue; 1859 if (pfd[i].fd == sockets[socknum].fd) 1860 break; 1861 } 1862 if (socknum >= sockets_alloc) { 1863 error_f("no socket for fd %d", pfd[i].fd); 1864 continue; 1865 } 1866 /* Process events */ 1867 switch (sockets[socknum].type) { 1868 case AUTH_SOCKET: 1869 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1870 break; 1871 if (npfd > maxfds) { 1872 debug3("out of fds (active %u >= limit %u); " 1873 "skipping accept", activefds, maxfds); 1874 break; 1875 } 1876 if (handle_socket_read(socknum) == 0) 1877 activefds++; 1878 break; 1879 case AUTH_CONNECTION: 1880 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1881 handle_conn_read(socknum) != 0) 1882 goto close_sock; 1883 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1884 handle_conn_write(socknum) != 0) { 1885 close_sock: 1886 if (activefds == 0) 1887 fatal("activefds == 0 at close_sock"); 1888 close_socket(&sockets[socknum]); 1889 activefds--; 1890 break; 1891 } 1892 break; 1893 default: 1894 break; 1895 } 1896 } 1897 } 1898 1899 static int 1900 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1901 { 1902 struct pollfd *pfd = *pfdp; 1903 size_t i, j, npfd = 0; 1904 time_t deadline; 1905 int r; 1906 1907 /* Count active sockets */ 1908 for (i = 0; i < sockets_alloc; i++) { 1909 switch (sockets[i].type) { 1910 case AUTH_SOCKET: 1911 case AUTH_CONNECTION: 1912 npfd++; 1913 break; 1914 case AUTH_UNUSED: 1915 break; 1916 default: 1917 fatal("Unknown socket type %d", sockets[i].type); 1918 break; 1919 } 1920 } 1921 if (npfd != *npfdp && 1922 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1923 fatal_f("recallocarray failed"); 1924 *pfdp = pfd; 1925 *npfdp = npfd; 1926 1927 for (i = j = 0; i < sockets_alloc; i++) { 1928 switch (sockets[i].type) { 1929 case AUTH_SOCKET: 1930 if (npfd > maxfds) { 1931 debug3("out of fds (active %zu >= limit %u); " 1932 "skipping arming listener", npfd, maxfds); 1933 break; 1934 } 1935 pfd[j].fd = sockets[i].fd; 1936 pfd[j].revents = 0; 1937 pfd[j].events = POLLIN; 1938 j++; 1939 break; 1940 case AUTH_CONNECTION: 1941 pfd[j].fd = sockets[i].fd; 1942 pfd[j].revents = 0; 1943 /* 1944 * Only prepare to read if we can handle a full-size 1945 * input read buffer and enqueue a max size reply.. 1946 */ 1947 if ((r = sshbuf_check_reserve(sockets[i].input, 1948 AGENT_RBUF_LEN)) == 0 && 1949 (r = sshbuf_check_reserve(sockets[i].output, 1950 AGENT_MAX_LEN)) == 0) 1951 pfd[j].events = POLLIN; 1952 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1953 fatal_fr(r, "reserve"); 1954 if (sshbuf_len(sockets[i].output) > 0) 1955 pfd[j].events |= POLLOUT; 1956 j++; 1957 break; 1958 default: 1959 break; 1960 } 1961 } 1962 deadline = reaper(); 1963 if (parent_alive_interval != 0) 1964 deadline = (deadline == 0) ? parent_alive_interval : 1965 MINIMUM(deadline, parent_alive_interval); 1966 if (deadline == 0) { 1967 *timeoutp = -1; /* INFTIM */ 1968 } else { 1969 if (deadline > INT_MAX / 1000) 1970 *timeoutp = INT_MAX / 1000; 1971 else 1972 *timeoutp = deadline * 1000; 1973 } 1974 return (1); 1975 } 1976 1977 static void 1978 cleanup_socket(void) 1979 { 1980 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1981 return; 1982 debug_f("cleanup"); 1983 if (socket_name[0]) 1984 unlink(socket_name); 1985 if (socket_dir[0]) 1986 rmdir(socket_dir); 1987 } 1988 1989 void 1990 cleanup_exit(int i) 1991 { 1992 cleanup_socket(); 1993 _exit(i); 1994 } 1995 1996 /*ARGSUSED*/ 1997 static void 1998 cleanup_handler(int sig) 1999 { 2000 cleanup_socket(); 2001 #ifdef ENABLE_PKCS11 2002 pkcs11_terminate(); 2003 #endif 2004 _exit(2); 2005 } 2006 2007 static void 2008 check_parent_exists(void) 2009 { 2010 /* 2011 * If our parent has exited then getppid() will return (pid_t)1, 2012 * so testing for that should be safe. 2013 */ 2014 if (parent_pid != -1 && getppid() != parent_pid) { 2015 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2016 cleanup_socket(); 2017 _exit(2); 2018 } 2019 } 2020 2021 static void 2022 usage(void) 2023 { 2024 fprintf(stderr, 2025 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2026 " [-P allowed_providers] [-t life]\n" 2027 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 2028 " [-t life] command [arg ...]\n" 2029 " ssh-agent [-c | -s] -k\n"); 2030 exit(1); 2031 } 2032 2033 int 2034 main(int ac, char **av) 2035 { 2036 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2037 int sock, ch, result, saved_errno; 2038 char *shell, *format, *pidstr, *agentsocket = NULL; 2039 #ifdef HAVE_SETRLIMIT 2040 struct rlimit rlim; 2041 #endif 2042 extern int optind; 2043 extern char *optarg; 2044 pid_t pid; 2045 char pidstrbuf[1 + 3 * sizeof pid]; 2046 size_t len; 2047 mode_t prev_mask; 2048 int timeout = -1; /* INFTIM */ 2049 struct pollfd *pfd = NULL; 2050 size_t npfd = 0; 2051 u_int maxfds; 2052 2053 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2054 sanitise_stdfd(); 2055 2056 /* drop */ 2057 setegid(getgid()); 2058 setgid(getgid()); 2059 setuid(geteuid()); 2060 2061 platform_disable_tracing(0); /* strict=no */ 2062 2063 #ifdef RLIMIT_NOFILE 2064 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2065 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2066 #endif 2067 2068 __progname = ssh_get_progname(av[0]); 2069 seed_rng(); 2070 2071 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2072 switch (ch) { 2073 case 'E': 2074 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2075 if (fingerprint_hash == -1) 2076 fatal("Invalid hash algorithm \"%s\"", optarg); 2077 break; 2078 case 'c': 2079 if (s_flag) 2080 usage(); 2081 c_flag++; 2082 break; 2083 case 'k': 2084 k_flag++; 2085 break; 2086 case 'O': 2087 if (strcmp(optarg, "no-restrict-websafe") == 0) 2088 restrict_websafe = 0; 2089 else 2090 fatal("Unknown -O option"); 2091 break; 2092 case 'P': 2093 if (allowed_providers != NULL) 2094 fatal("-P option already specified"); 2095 allowed_providers = xstrdup(optarg); 2096 break; 2097 case 's': 2098 if (c_flag) 2099 usage(); 2100 s_flag++; 2101 break; 2102 case 'd': 2103 if (d_flag || D_flag) 2104 usage(); 2105 d_flag++; 2106 break; 2107 case 'D': 2108 if (d_flag || D_flag) 2109 usage(); 2110 D_flag++; 2111 break; 2112 case 'a': 2113 agentsocket = optarg; 2114 break; 2115 case 't': 2116 if ((lifetime = convtime(optarg)) == -1) { 2117 fprintf(stderr, "Invalid lifetime\n"); 2118 usage(); 2119 } 2120 break; 2121 case 'x': 2122 xcount = 0; 2123 break; 2124 default: 2125 usage(); 2126 } 2127 } 2128 ac -= optind; 2129 av += optind; 2130 2131 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2132 usage(); 2133 2134 if (allowed_providers == NULL) 2135 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2136 2137 if (ac == 0 && !c_flag && !s_flag) { 2138 shell = getenv("SHELL"); 2139 if (shell != NULL && (len = strlen(shell)) > 2 && 2140 strncmp(shell + len - 3, "csh", 3) == 0) 2141 c_flag = 1; 2142 } 2143 if (k_flag) { 2144 const char *errstr = NULL; 2145 2146 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2147 if (pidstr == NULL) { 2148 fprintf(stderr, "%s not set, cannot kill agent\n", 2149 SSH_AGENTPID_ENV_NAME); 2150 exit(1); 2151 } 2152 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2153 if (errstr) { 2154 fprintf(stderr, 2155 "%s=\"%s\", which is not a good PID: %s\n", 2156 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2157 exit(1); 2158 } 2159 if (kill(pid, SIGTERM) == -1) { 2160 perror("kill"); 2161 exit(1); 2162 } 2163 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2164 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2165 printf(format, SSH_AGENTPID_ENV_NAME); 2166 printf("echo Agent pid %ld killed;\n", (long)pid); 2167 exit(0); 2168 } 2169 2170 /* 2171 * Minimum file descriptors: 2172 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2173 * a few spare for libc / stack protectors / sanitisers, etc. 2174 */ 2175 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2176 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2177 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2178 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2179 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2180 2181 parent_pid = getpid(); 2182 2183 if (agentsocket == NULL) { 2184 /* Create private directory for agent socket */ 2185 mktemp_proto(socket_dir, sizeof(socket_dir)); 2186 if (mkdtemp(socket_dir) == NULL) { 2187 perror("mkdtemp: private socket dir"); 2188 exit(1); 2189 } 2190 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2191 (long)parent_pid); 2192 } else { 2193 /* Try to use specified agent socket */ 2194 socket_dir[0] = '\0'; 2195 strlcpy(socket_name, agentsocket, sizeof socket_name); 2196 } 2197 2198 /* 2199 * Create socket early so it will exist before command gets run from 2200 * the parent. 2201 */ 2202 prev_mask = umask(0177); 2203 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2204 if (sock < 0) { 2205 /* XXX - unix_listener() calls error() not perror() */ 2206 *socket_name = '\0'; /* Don't unlink any existing file */ 2207 cleanup_exit(1); 2208 } 2209 umask(prev_mask); 2210 2211 /* 2212 * Fork, and have the parent execute the command, if any, or present 2213 * the socket data. The child continues as the authentication agent. 2214 */ 2215 if (D_flag || d_flag) { 2216 log_init(__progname, 2217 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2218 SYSLOG_FACILITY_AUTH, 1); 2219 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2220 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2221 SSH_AUTHSOCKET_ENV_NAME); 2222 printf("echo Agent pid %ld;\n", (long)parent_pid); 2223 fflush(stdout); 2224 goto skip; 2225 } 2226 pid = fork(); 2227 if (pid == -1) { 2228 perror("fork"); 2229 cleanup_exit(1); 2230 } 2231 if (pid != 0) { /* Parent - execute the given command. */ 2232 close(sock); 2233 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2234 if (ac == 0) { 2235 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2236 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2237 SSH_AUTHSOCKET_ENV_NAME); 2238 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2239 SSH_AGENTPID_ENV_NAME); 2240 printf("echo Agent pid %ld;\n", (long)pid); 2241 exit(0); 2242 } 2243 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2244 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2245 perror("setenv"); 2246 exit(1); 2247 } 2248 execvp(av[0], av); 2249 perror(av[0]); 2250 exit(1); 2251 } 2252 /* child */ 2253 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2254 2255 if (setsid() == -1) { 2256 error("setsid: %s", strerror(errno)); 2257 cleanup_exit(1); 2258 } 2259 2260 (void)chdir("/"); 2261 if (stdfd_devnull(1, 1, 1) == -1) 2262 error_f("stdfd_devnull failed"); 2263 2264 #ifdef HAVE_SETRLIMIT 2265 /* deny core dumps, since memory contains unencrypted private keys */ 2266 rlim.rlim_cur = rlim.rlim_max = 0; 2267 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2268 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2269 cleanup_exit(1); 2270 } 2271 #endif 2272 2273 skip: 2274 2275 cleanup_pid = getpid(); 2276 2277 #ifdef ENABLE_PKCS11 2278 pkcs11_init(0); 2279 #endif 2280 new_socket(AUTH_SOCKET, sock); 2281 if (ac > 0) 2282 parent_alive_interval = 10; 2283 idtab_init(); 2284 ssh_signal(SIGPIPE, SIG_IGN); 2285 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2286 ssh_signal(SIGHUP, cleanup_handler); 2287 ssh_signal(SIGTERM, cleanup_handler); 2288 2289 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2290 fatal("%s: pledge: %s", __progname, strerror(errno)); 2291 platform_pledge_agent(); 2292 2293 while (1) { 2294 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2295 result = poll(pfd, npfd, timeout); 2296 saved_errno = errno; 2297 if (parent_alive_interval != 0) 2298 check_parent_exists(); 2299 (void) reaper(); /* remove expired keys */ 2300 if (result == -1) { 2301 if (saved_errno == EINTR) 2302 continue; 2303 fatal("poll: %s", strerror(saved_errno)); 2304 } else if (result > 0) 2305 after_poll(pfd, npfd, maxfds); 2306 } 2307 /* NOTREACHED */ 2308 } 2309