1 /* $NetBSD: ssh-agent.c,v 1.34 2022/10/05 22:39:36 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.292 2022/09/17 10:11:29 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * The authentication agent program. 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 __RCSID("$NetBSD: ssh-agent.c,v 1.34 2022/10/05 22:39:36 christos Exp $"); 41 42 #include <sys/param.h> /* MIN MAX */ 43 #include <sys/types.h> 44 #include <sys/time.h> 45 #include <sys/queue.h> 46 #include <sys/resource.h> 47 #include <sys/socket.h> 48 #include <sys/stat.h> 49 #include <sys/un.h> 50 #include <sys/wait.h> 51 52 #ifdef WITH_OPENSSL 53 #include <openssl/evp.h> 54 #endif 55 56 #include <errno.h> 57 #include <fcntl.h> 58 #include <paths.h> 59 #include <poll.h> 60 #include <signal.h> 61 #include <stdlib.h> 62 #include <stdio.h> 63 #include <string.h> 64 #include <stdarg.h> 65 #include <limits.h> 66 #include <time.h> 67 #include <unistd.h> 68 #include <util.h> 69 70 #include "xmalloc.h" 71 #include "ssh.h" 72 #include "ssh2.h" 73 #include "sshbuf.h" 74 #include "sshkey.h" 75 #include "authfd.h" 76 #include "compat.h" 77 #include "log.h" 78 #include "misc.h" 79 #include "getpeereid.h" 80 #include "digest.h" 81 #include "ssherr.h" 82 #include "match.h" 83 #include "msg.h" 84 #include "ssherr.h" 85 #include "pathnames.h" 86 #include "ssh-pkcs11.h" 87 #include "sk-api.h" 88 #include "myproposal.h" 89 90 #ifndef DEFAULT_ALLOWED_PROVIDERS 91 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/pkg/lib*/*" 92 #endif 93 94 /* Maximum accepted message length */ 95 #define AGENT_MAX_LEN (256*1024) 96 /* Maximum bytes to read from client socket */ 97 #define AGENT_RBUF_LEN (4096) 98 /* Maximum number of recorded session IDs/hostkeys per connection */ 99 #define AGENT_MAX_SESSION_IDS 16 100 /* Maximum size of session ID */ 101 #define AGENT_MAX_SID_LEN 128 102 /* Maximum number of destination constraints to accept on a key */ 103 #define AGENT_MAX_DEST_CONSTRAINTS 1024 104 105 /* XXX store hostkey_sid in a refcounted tree */ 106 107 typedef enum { 108 AUTH_UNUSED = 0, 109 AUTH_SOCKET = 1, 110 AUTH_CONNECTION = 2, 111 } sock_type; 112 113 struct hostkey_sid { 114 struct sshkey *key; 115 struct sshbuf *sid; 116 int forwarded; 117 }; 118 119 typedef struct socket_entry { 120 int fd; 121 sock_type type; 122 struct sshbuf *input; 123 struct sshbuf *output; 124 struct sshbuf *request; 125 size_t nsession_ids; 126 struct hostkey_sid *session_ids; 127 } SocketEntry; 128 129 u_int sockets_alloc = 0; 130 SocketEntry *sockets = NULL; 131 132 typedef struct identity { 133 TAILQ_ENTRY(identity) next; 134 struct sshkey *key; 135 char *comment; 136 char *provider; 137 time_t death; 138 u_int confirm; 139 char *sk_provider; 140 struct dest_constraint *dest_constraints; 141 size_t ndest_constraints; 142 } Identity; 143 144 struct idtable { 145 int nentries; 146 TAILQ_HEAD(idqueue, identity) idlist; 147 }; 148 149 /* private key table */ 150 struct idtable *idtab; 151 152 int max_fd = 0; 153 154 /* pid of shell == parent of agent */ 155 pid_t parent_pid = -1; 156 time_t parent_alive_interval = 0; 157 158 /* pid of process for which cleanup_socket is applicable */ 159 pid_t cleanup_pid = 0; 160 161 /* pathname and directory for AUTH_SOCKET */ 162 char socket_name[PATH_MAX]; 163 char socket_dir[PATH_MAX]; 164 165 /* Pattern-list of allowed PKCS#11/Security key paths */ 166 static char *allowed_providers; 167 168 /* locking */ 169 #define LOCK_SIZE 32 170 #define LOCK_SALT_SIZE 16 171 #define LOCK_ROUNDS 1 172 int locked = 0; 173 u_char lock_pwhash[LOCK_SIZE]; 174 u_char lock_salt[LOCK_SALT_SIZE]; 175 176 extern char *__progname; 177 178 /* Default lifetime in seconds (0 == forever) */ 179 static int lifetime = 0; 180 181 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 182 183 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 184 static int restrict_websafe = 1; 185 186 static void 187 close_socket(SocketEntry *e) 188 { 189 size_t i; 190 191 close(e->fd); 192 sshbuf_free(e->input); 193 sshbuf_free(e->output); 194 sshbuf_free(e->request); 195 for (i = 0; i < e->nsession_ids; i++) { 196 sshkey_free(e->session_ids[i].key); 197 sshbuf_free(e->session_ids[i].sid); 198 } 199 free(e->session_ids); 200 memset(e, '\0', sizeof(*e)); 201 e->fd = -1; 202 e->type = AUTH_UNUSED; 203 } 204 205 static void 206 idtab_init(void) 207 { 208 idtab = xcalloc(1, sizeof(*idtab)); 209 TAILQ_INIT(&idtab->idlist); 210 idtab->nentries = 0; 211 } 212 213 static void 214 free_dest_constraint_hop(struct dest_constraint_hop *dch) 215 { 216 u_int i; 217 218 if (dch == NULL) 219 return; 220 free(dch->user); 221 free(dch->hostname); 222 for (i = 0; i < dch->nkeys; i++) 223 sshkey_free(dch->keys[i]); 224 free(dch->keys); 225 free(dch->key_is_ca); 226 } 227 228 static void 229 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 230 { 231 size_t i; 232 233 for (i = 0; i < ndcs; i++) { 234 free_dest_constraint_hop(&dcs[i].from); 235 free_dest_constraint_hop(&dcs[i].to); 236 } 237 free(dcs); 238 } 239 240 static void 241 free_identity(Identity *id) 242 { 243 sshkey_free(id->key); 244 free(id->provider); 245 free(id->comment); 246 free(id->sk_provider); 247 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 248 free(id); 249 } 250 251 /* 252 * Match 'key' against the key/CA list in a destination constraint hop 253 * Returns 0 on success or -1 otherwise. 254 */ 255 static int 256 match_key_hop(const char *tag, const struct sshkey *key, 257 const struct dest_constraint_hop *dch) 258 { 259 const char *reason = NULL; 260 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 261 u_int i; 262 char *fp; 263 264 if (key == NULL) 265 return -1; 266 /* XXX logspam */ 267 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 268 SSH_FP_DEFAULT)) == NULL) 269 fatal_f("fingerprint failed"); 270 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 271 tag, hostname, sshkey_type(key), fp, dch->nkeys); 272 free(fp); 273 for (i = 0; i < dch->nkeys; i++) { 274 if (dch->keys[i] == NULL) 275 return -1; 276 /* XXX logspam */ 277 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 278 SSH_FP_DEFAULT)) == NULL) 279 fatal_f("fingerprint failed"); 280 debug3_f("%s: key %u: %s%s %s", tag, i, 281 dch->key_is_ca[i] ? "CA " : "", 282 sshkey_type(dch->keys[i]), fp); 283 free(fp); 284 if (!sshkey_is_cert(key)) { 285 /* plain key */ 286 if (dch->key_is_ca[i] || 287 !sshkey_equal(key, dch->keys[i])) 288 continue; 289 return 0; 290 } 291 /* certificate */ 292 if (!dch->key_is_ca[i]) 293 continue; 294 if (key->cert == NULL || key->cert->signature_key == NULL) 295 return -1; /* shouldn't happen */ 296 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 297 continue; 298 if (sshkey_cert_check_host(key, hostname, 1, 299 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 300 debug_f("cert %s / hostname %s rejected: %s", 301 key->cert->key_id, hostname, reason); 302 continue; 303 } 304 return 0; 305 } 306 return -1; 307 } 308 309 /* Check destination constraints on an identity against the hostkey/user */ 310 static int 311 permitted_by_dest_constraints(const struct sshkey *fromkey, 312 const struct sshkey *tokey, Identity *id, const char *user, 313 const char **hostnamep) 314 { 315 size_t i; 316 struct dest_constraint *d; 317 318 if (hostnamep != NULL) 319 *hostnamep = NULL; 320 for (i = 0; i < id->ndest_constraints; i++) { 321 d = id->dest_constraints + i; 322 /* XXX remove logspam */ 323 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 324 i, d->from.user ? d->from.user : "", 325 d->from.user ? "@" : "", 326 d->from.hostname ? d->from.hostname : "(ORIGIN)", 327 d->from.nkeys, 328 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 329 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 330 331 /* Match 'from' key */ 332 if (fromkey == NULL) { 333 /* We are matching the first hop */ 334 if (d->from.hostname != NULL || d->from.nkeys != 0) 335 continue; 336 } else if (match_key_hop("from", fromkey, &d->from) != 0) 337 continue; 338 339 /* Match 'to' key */ 340 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 341 continue; 342 343 /* Match user if specified */ 344 if (d->to.user != NULL && user != NULL && 345 !match_pattern(user, d->to.user)) 346 continue; 347 348 /* successfully matched this constraint */ 349 if (hostnamep != NULL) 350 *hostnamep = d->to.hostname; 351 debug2_f("allowed for hostname %s", 352 d->to.hostname == NULL ? "*" : d->to.hostname); 353 return 0; 354 } 355 /* no match */ 356 debug2_f("%s identity \"%s\" not permitted for this destination", 357 sshkey_type(id->key), id->comment); 358 return -1; 359 } 360 361 /* 362 * Check whether hostkeys on a SocketEntry and the optionally specified user 363 * are permitted by the destination constraints on the Identity. 364 * Returns 0 on success or -1 otherwise. 365 */ 366 static int 367 identity_permitted(Identity *id, SocketEntry *e, char *user, 368 const char **forward_hostnamep, const char **last_hostnamep) 369 { 370 size_t i; 371 const char **hp; 372 struct hostkey_sid *hks; 373 const struct sshkey *fromkey = NULL; 374 const char *test_user; 375 char *fp1, *fp2; 376 377 /* XXX remove logspam */ 378 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 379 "%zu constraints", sshkey_type(id->key), id->comment, 380 e->nsession_ids, id->ndest_constraints); 381 if (id->ndest_constraints == 0) 382 return 0; /* unconstrained */ 383 if (e->nsession_ids == 0) 384 return 0; /* local use */ 385 /* 386 * Walk through the hops recorded by session_id and try to find a 387 * constraint that satisfies each. 388 */ 389 for (i = 0; i < e->nsession_ids; i++) { 390 hks = e->session_ids + i; 391 if (hks->key == NULL) 392 fatal_f("internal error: no bound key"); 393 /* XXX remove logspam */ 394 fp1 = fp2 = NULL; 395 if (fromkey != NULL && 396 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 397 SSH_FP_DEFAULT)) == NULL) 398 fatal_f("fingerprint failed"); 399 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 400 SSH_FP_DEFAULT)) == NULL) 401 fatal_f("fingerprint failed"); 402 debug3_f("socketentry fd=%d, entry %zu %s, " 403 "from hostkey %s %s to user %s hostkey %s %s", 404 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 405 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 406 fromkey ? fp1 : "", user ? user : "(ANY)", 407 sshkey_type(hks->key), fp2); 408 free(fp1); 409 free(fp2); 410 /* 411 * Record the hostnames for the initial forwarding and 412 * the final destination. 413 */ 414 hp = NULL; 415 if (i == e->nsession_ids - 1) 416 hp = last_hostnamep; 417 else if (i == 0) 418 hp = forward_hostnamep; 419 /* Special handling for final recorded binding */ 420 test_user = NULL; 421 if (i == e->nsession_ids - 1) { 422 /* Can only check user at final hop */ 423 test_user = user; 424 /* 425 * user is only presented for signature requests. 426 * If this is the case, make sure last binding is not 427 * for a forwarding. 428 */ 429 if (hks->forwarded && user != NULL) { 430 error_f("tried to sign on forwarding hop"); 431 return -1; 432 } 433 } else if (!hks->forwarded) { 434 error_f("tried to forward though signing bind"); 435 return -1; 436 } 437 if (permitted_by_dest_constraints(fromkey, hks->key, id, 438 test_user, hp) != 0) 439 return -1; 440 fromkey = hks->key; 441 } 442 /* 443 * Another special case: if the last bound session ID was for a 444 * forwarding, and this function is not being called to check a sign 445 * request (i.e. no 'user' supplied), then only permit the key if 446 * there is a permission that would allow it to be used at another 447 * destination. This hides keys that are allowed to be used to 448 * authenticate *to* a host but not permitted for *use* beyond it. 449 */ 450 hks = &e->session_ids[e->nsession_ids - 1]; 451 if (hks->forwarded && user == NULL && 452 permitted_by_dest_constraints(hks->key, NULL, id, 453 NULL, NULL) != 0) { 454 debug3_f("key permitted at host but not after"); 455 return -1; 456 } 457 458 /* success */ 459 return 0; 460 } 461 462 /* return matching private key for given public key */ 463 static Identity * 464 lookup_identity(struct sshkey *key) 465 { 466 Identity *id; 467 468 TAILQ_FOREACH(id, &idtab->idlist, next) { 469 if (sshkey_equal(key, id->key)) 470 return (id); 471 } 472 return (NULL); 473 } 474 475 /* Check confirmation of keysign request */ 476 static int 477 confirm_key(Identity *id, const char *extra) 478 { 479 char *p; 480 int ret = -1; 481 482 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 483 if (p != NULL && 484 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 485 id->comment, p, 486 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 487 ret = 0; 488 free(p); 489 490 return (ret); 491 } 492 493 static void 494 send_status(SocketEntry *e, int success) 495 { 496 int r; 497 498 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 499 (r = sshbuf_put_u8(e->output, success ? 500 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 501 fatal_fr(r, "compose"); 502 } 503 504 /* send list of supported public keys to 'client' */ 505 static void 506 process_request_identities(SocketEntry *e) 507 { 508 Identity *id; 509 struct sshbuf *msg, *keys; 510 int r; 511 u_int nentries = 0; 512 513 debug2_f("entering"); 514 515 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 516 fatal_f("sshbuf_new failed"); 517 TAILQ_FOREACH(id, &idtab->idlist, next) { 518 /* identity not visible, don't include in response */ 519 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 520 continue; 521 if ((r = sshkey_puts_opts(id->key, keys, 522 SSHKEY_SERIALIZE_INFO)) != 0 || 523 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 524 error_fr(r, "compose key/comment"); 525 continue; 526 } 527 nentries++; 528 } 529 debug2_f("replying with %u allowed of %u available keys", 530 nentries, idtab->nentries); 531 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 532 (r = sshbuf_put_u32(msg, nentries)) != 0 || 533 (r = sshbuf_putb(msg, keys)) != 0) 534 fatal_fr(r, "compose"); 535 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 536 fatal_fr(r, "enqueue"); 537 sshbuf_free(msg); 538 sshbuf_free(keys); 539 } 540 541 542 static const char * 543 agent_decode_alg(struct sshkey *key, u_int flags) 544 { 545 if (key->type == KEY_RSA) { 546 if (flags & SSH_AGENT_RSA_SHA2_256) 547 return "rsa-sha2-256"; 548 else if (flags & SSH_AGENT_RSA_SHA2_512) 549 return "rsa-sha2-512"; 550 } else if (key->type == KEY_RSA_CERT) { 551 if (flags & SSH_AGENT_RSA_SHA2_256) 552 return "rsa-sha2-256-cert-v01@openssh.com"; 553 else if (flags & SSH_AGENT_RSA_SHA2_512) 554 return "rsa-sha2-512-cert-v01@openssh.com"; 555 } 556 return NULL; 557 } 558 559 /* 560 * Attempt to parse the contents of a buffer as a SSH publickey userauth 561 * request, checking its contents for consistency and matching the embedded 562 * key against the one that is being used for signing. 563 * Note: does not modify msg buffer. 564 * Optionally extract the username, session ID and/or hostkey from the request. 565 */ 566 static int 567 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 568 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 569 { 570 struct sshbuf *b = NULL, *sess_id = NULL; 571 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 572 int r; 573 u_char t, sig_follows; 574 struct sshkey *mkey = NULL, *hostkey = NULL; 575 576 if (userp != NULL) 577 *userp = NULL; 578 if (sess_idp != NULL) 579 *sess_idp = NULL; 580 if (hostkeyp != NULL) 581 *hostkeyp = NULL; 582 if ((b = sshbuf_fromb(msg)) == NULL) 583 fatal_f("sshbuf_fromb"); 584 585 /* SSH userauth request */ 586 if ((r = sshbuf_froms(b, &sess_id)) != 0) 587 goto out; 588 if (sshbuf_len(sess_id) == 0) { 589 r = SSH_ERR_INVALID_FORMAT; 590 goto out; 591 } 592 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 593 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 594 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 595 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 596 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 597 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 598 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 599 goto out; 600 if (t != SSH2_MSG_USERAUTH_REQUEST || 601 sig_follows != 1 || 602 strcmp(service, "ssh-connection") != 0 || 603 !sshkey_equal(expected_key, mkey) || 604 sshkey_type_from_name(pkalg) != expected_key->type) { 605 r = SSH_ERR_INVALID_FORMAT; 606 goto out; 607 } 608 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 609 if ((r = sshkey_froms(b, &hostkey)) != 0) 610 goto out; 611 } else if (strcmp(method, "publickey") != 0) { 612 r = SSH_ERR_INVALID_FORMAT; 613 goto out; 614 } 615 if (sshbuf_len(b) != 0) { 616 r = SSH_ERR_INVALID_FORMAT; 617 goto out; 618 } 619 /* success */ 620 r = 0; 621 debug3_f("well formed userauth"); 622 if (userp != NULL) { 623 *userp = user; 624 user = NULL; 625 } 626 if (sess_idp != NULL) { 627 *sess_idp = sess_id; 628 sess_id = NULL; 629 } 630 if (hostkeyp != NULL) { 631 *hostkeyp = hostkey; 632 hostkey = NULL; 633 } 634 out: 635 sshbuf_free(b); 636 sshbuf_free(sess_id); 637 free(user); 638 free(service); 639 free(method); 640 free(pkalg); 641 sshkey_free(mkey); 642 sshkey_free(hostkey); 643 return r; 644 } 645 646 /* 647 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 648 * Note: does not modify buffer. 649 */ 650 static int 651 parse_sshsig_request(struct sshbuf *msg) 652 { 653 int r; 654 struct sshbuf *b; 655 656 if ((b = sshbuf_fromb(msg)) == NULL) 657 fatal_f("sshbuf_fromb"); 658 659 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 660 (r = sshbuf_consume(b, 6)) != 0 || 661 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 662 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 663 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 664 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 665 goto out; 666 if (sshbuf_len(b) != 0) { 667 r = SSH_ERR_INVALID_FORMAT; 668 goto out; 669 } 670 /* success */ 671 r = 0; 672 out: 673 sshbuf_free(b); 674 return r; 675 } 676 677 /* 678 * This function inspects a message to be signed by a FIDO key that has a 679 * web-like application string (i.e. one that does not begin with "ssh:". 680 * It checks that the message is one of those expected for SSH operations 681 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 682 * for the web. 683 */ 684 static int 685 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 686 { 687 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 688 debug_f("signed data matches public key userauth request"); 689 return 1; 690 } 691 if (parse_sshsig_request(data) == 0) { 692 debug_f("signed data matches SSHSIG signature request"); 693 return 1; 694 } 695 696 /* XXX check CA signature operation */ 697 698 error("web-origin key attempting to sign non-SSH message"); 699 return 0; 700 } 701 702 static int 703 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 704 { 705 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 706 return SSH_ERR_INVALID_ARGUMENT; 707 if (sshbuf_len(a) != sshbuf_len(b)) 708 return SSH_ERR_INVALID_FORMAT; 709 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 710 return SSH_ERR_INVALID_FORMAT; 711 return 0; 712 } 713 714 /* ssh2 only */ 715 static void 716 process_sign_request2(SocketEntry *e) 717 { 718 u_char *signature = NULL; 719 size_t slen = 0; 720 u_int compat = 0, flags; 721 int r, ok = -1, retried = 0; 722 char *fp = NULL, *pin = NULL, *prompt = NULL; 723 char *user = NULL, *sig_dest = NULL; 724 const char *fwd_host = NULL, *dest_host = NULL; 725 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 726 struct sshkey *key = NULL, *hostkey = NULL; 727 struct identity *id; 728 struct notifier_ctx *notifier = NULL; 729 730 debug_f("entering"); 731 732 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 733 fatal_f("sshbuf_new failed"); 734 if ((r = sshkey_froms(e->request, &key)) != 0 || 735 (r = sshbuf_get_stringb(e->request, data)) != 0 || 736 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 737 error_fr(r, "parse"); 738 goto send; 739 } 740 741 if ((id = lookup_identity(key)) == NULL) { 742 verbose_f("%s key not found", sshkey_type(key)); 743 goto send; 744 } 745 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 746 SSH_FP_DEFAULT)) == NULL) 747 fatal_f("fingerprint failed"); 748 749 if (id->ndest_constraints != 0) { 750 if (e->nsession_ids == 0) { 751 logit_f("refusing use of destination-constrained key " 752 "to sign on unbound connection"); 753 goto send; 754 } 755 if (parse_userauth_request(data, key, &user, &sid, 756 &hostkey) != 0) { 757 logit_f("refusing use of destination-constrained key " 758 "to sign an unidentified signature"); 759 goto send; 760 } 761 /* XXX logspam */ 762 debug_f("user=%s", user); 763 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 764 goto send; 765 /* XXX display fwd_host/dest_host in askpass UI */ 766 /* 767 * Ensure that the session ID is the most recent one 768 * registered on the socket - it should have been bound by 769 * ssh immediately before userauth. 770 */ 771 if (buf_equal(sid, 772 e->session_ids[e->nsession_ids - 1].sid) != 0) { 773 error_f("unexpected session ID (%zu listed) on " 774 "signature request for target user %s with " 775 "key %s %s", e->nsession_ids, user, 776 sshkey_type(id->key), fp); 777 goto send; 778 } 779 /* 780 * Ensure that the hostkey embedded in the signature matches 781 * the one most recently bound to the socket. An exception is 782 * made for the initial forwarding hop. 783 */ 784 if (e->nsession_ids > 1 && hostkey == NULL) { 785 error_f("refusing use of destination-constrained key: " 786 "no hostkey recorded in signature for forwarded " 787 "connection"); 788 goto send; 789 } 790 if (hostkey != NULL && !sshkey_equal(hostkey, 791 e->session_ids[e->nsession_ids - 1].key)) { 792 error_f("refusing use of destination-constrained key: " 793 "mismatch between hostkey in request and most " 794 "recently bound session"); 795 goto send; 796 } 797 xasprintf(&sig_dest, "public key authentication request for " 798 "user \"%s\" to listed host", user); 799 } 800 if (id->confirm && confirm_key(id, sig_dest) != 0) { 801 verbose_f("user refused key"); 802 goto send; 803 } 804 if (sshkey_is_sk(id->key)) { 805 if (restrict_websafe && 806 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 807 !check_websafe_message_contents(key, data)) { 808 /* error already logged */ 809 goto send; 810 } 811 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 812 notifier = notify_start(0, 813 "Confirm user presence for key %s %s%s%s", 814 sshkey_type(id->key), fp, 815 sig_dest == NULL ? "" : "\n", 816 sig_dest == NULL ? "" : sig_dest); 817 } 818 } 819 retry_pin: 820 if ((r = sshkey_sign(id->key, &signature, &slen, 821 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 822 id->sk_provider, pin, compat)) != 0) { 823 debug_fr(r, "sshkey_sign"); 824 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 825 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 826 notify_complete(notifier, NULL); 827 notifier = NULL; 828 /* XXX include sig_dest */ 829 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 830 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 831 " and confirm user presence " : " ", 832 sshkey_type(id->key), fp); 833 pin = read_passphrase(prompt, RP_USE_ASKPASS); 834 retried = 1; 835 goto retry_pin; 836 } 837 error_fr(r, "sshkey_sign"); 838 goto send; 839 } 840 /* Success */ 841 ok = 0; 842 send: 843 debug_f("good signature"); 844 notify_complete(notifier, "User presence confirmed"); 845 846 if (ok == 0) { 847 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 848 (r = sshbuf_put_string(msg, signature, slen)) != 0) 849 fatal_fr(r, "compose"); 850 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 851 fatal_fr(r, "compose failure"); 852 853 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 854 fatal_fr(r, "enqueue"); 855 856 sshbuf_free(sid); 857 sshbuf_free(data); 858 sshbuf_free(msg); 859 sshkey_free(key); 860 sshkey_free(hostkey); 861 free(fp); 862 free(signature); 863 free(sig_dest); 864 free(user); 865 free(prompt); 866 if (pin != NULL) 867 freezero(pin, strlen(pin)); 868 } 869 870 /* shared */ 871 static void 872 process_remove_identity(SocketEntry *e) 873 { 874 int r, success = 0; 875 struct sshkey *key = NULL; 876 Identity *id; 877 878 debug2_f("entering"); 879 if ((r = sshkey_froms(e->request, &key)) != 0) { 880 error_fr(r, "parse key"); 881 goto done; 882 } 883 if ((id = lookup_identity(key)) == NULL) { 884 debug_f("key not found"); 885 goto done; 886 } 887 /* identity not visible, cannot be removed */ 888 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 889 goto done; /* error already logged */ 890 /* We have this key, free it. */ 891 if (idtab->nentries < 1) 892 fatal_f("internal error: nentries %d", idtab->nentries); 893 TAILQ_REMOVE(&idtab->idlist, id, next); 894 free_identity(id); 895 idtab->nentries--; 896 success = 1; 897 done: 898 sshkey_free(key); 899 send_status(e, success); 900 } 901 902 static void 903 process_remove_all_identities(SocketEntry *e) 904 { 905 Identity *id; 906 907 debug2_f("entering"); 908 /* Loop over all identities and clear the keys. */ 909 for (id = TAILQ_FIRST(&idtab->idlist); id; 910 id = TAILQ_FIRST(&idtab->idlist)) { 911 TAILQ_REMOVE(&idtab->idlist, id, next); 912 free_identity(id); 913 } 914 915 /* Mark that there are no identities. */ 916 idtab->nentries = 0; 917 918 /* Send success. */ 919 send_status(e, 1); 920 } 921 922 /* removes expired keys and returns number of seconds until the next expiry */ 923 static time_t 924 reaper(void) 925 { 926 time_t deadline = 0, now = monotime(); 927 Identity *id, *nxt; 928 929 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 930 nxt = TAILQ_NEXT(id, next); 931 if (id->death == 0) 932 continue; 933 if (now >= id->death) { 934 debug("expiring key '%s'", id->comment); 935 TAILQ_REMOVE(&idtab->idlist, id, next); 936 free_identity(id); 937 idtab->nentries--; 938 } else 939 deadline = (deadline == 0) ? id->death : 940 MINIMUM(deadline, id->death); 941 } 942 if (deadline == 0 || deadline <= now) 943 return 0; 944 else 945 return (deadline - now); 946 } 947 948 static int 949 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 950 { 951 u_char key_is_ca; 952 size_t elen = 0; 953 int r; 954 struct sshkey *k = NULL; 955 char *fp; 956 957 memset(dch, '\0', sizeof(*dch)); 958 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 959 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 960 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 961 error_fr(r, "parse"); 962 goto out; 963 } 964 if (elen != 0) { 965 error_f("unsupported extensions (len %zu)", elen); 966 r = SSH_ERR_FEATURE_UNSUPPORTED; 967 goto out; 968 } 969 if (*dch->hostname == '\0') { 970 free(dch->hostname); 971 dch->hostname = NULL; 972 } 973 if (*dch->user == '\0') { 974 free(dch->user); 975 dch->user = NULL; 976 } 977 while (sshbuf_len(b) != 0) { 978 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 979 dch->nkeys + 1, sizeof(*dch->keys)); 980 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 981 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 982 if ((r = sshkey_froms(b, &k)) != 0 || 983 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 984 goto out; 985 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 986 SSH_FP_DEFAULT)) == NULL) 987 fatal_f("fingerprint failed"); 988 debug3_f("%s%s%s: adding %skey %s %s", 989 dch->user == NULL ? "" : dch->user, 990 dch->user == NULL ? "" : "@", 991 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 992 free(fp); 993 dch->keys[dch->nkeys] = k; 994 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 995 dch->nkeys++; 996 k = NULL; /* transferred */ 997 } 998 /* success */ 999 r = 0; 1000 out: 1001 sshkey_free(k); 1002 return r; 1003 } 1004 1005 static int 1006 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1007 { 1008 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1009 int r; 1010 size_t elen = 0; 1011 1012 debug3_f("entering"); 1013 1014 memset(dc, '\0', sizeof(*dc)); 1015 if ((r = sshbuf_froms(m, &b)) != 0 || 1016 (r = sshbuf_froms(b, &frombuf)) != 0 || 1017 (r = sshbuf_froms(b, &tobuf)) != 0 || 1018 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1019 error_fr(r, "parse"); 1020 goto out; 1021 } 1022 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1023 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1024 goto out; /* already logged */ 1025 if (elen != 0) { 1026 error_f("unsupported extensions (len %zu)", elen); 1027 r = SSH_ERR_FEATURE_UNSUPPORTED; 1028 goto out; 1029 } 1030 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1031 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1032 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1033 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1034 /* check consistency */ 1035 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1036 dc->from.user != NULL) { 1037 error_f("inconsistent \"from\" specification"); 1038 r = SSH_ERR_INVALID_FORMAT; 1039 goto out; 1040 } 1041 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1042 error_f("incomplete \"to\" specification"); 1043 r = SSH_ERR_INVALID_FORMAT; 1044 goto out; 1045 } 1046 /* success */ 1047 r = 0; 1048 out: 1049 sshbuf_free(b); 1050 sshbuf_free(frombuf); 1051 sshbuf_free(tobuf); 1052 return r; 1053 } 1054 1055 static int 1056 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1057 struct dest_constraint **dcsp, size_t *ndcsp) 1058 { 1059 char *ext_name = NULL; 1060 int r; 1061 struct sshbuf *b = NULL; 1062 1063 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1064 error_fr(r, "parse constraint extension"); 1065 goto out; 1066 } 1067 debug_f("constraint ext %s", ext_name); 1068 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1069 if (sk_providerp == NULL) { 1070 error_f("%s not valid here", ext_name); 1071 r = SSH_ERR_INVALID_FORMAT; 1072 goto out; 1073 } 1074 if (*sk_providerp != NULL) { 1075 error_f("%s already set", ext_name); 1076 r = SSH_ERR_INVALID_FORMAT; 1077 goto out; 1078 } 1079 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1080 error_fr(r, "parse %s", ext_name); 1081 goto out; 1082 } 1083 } else if (strcmp(ext_name, 1084 "restrict-destination-v00@openssh.com") == 0) { 1085 if (*dcsp != NULL) { 1086 error_f("%s already set", ext_name); 1087 goto out; 1088 } 1089 if ((r = sshbuf_froms(m, &b)) != 0) { 1090 error_fr(r, "parse %s outer", ext_name); 1091 goto out; 1092 } 1093 while (sshbuf_len(b) != 0) { 1094 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1095 error_f("too many %s constraints", ext_name); 1096 goto out; 1097 } 1098 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1099 sizeof(**dcsp)); 1100 if ((r = parse_dest_constraint(b, 1101 *dcsp + (*ndcsp)++)) != 0) 1102 goto out; /* error already logged */ 1103 } 1104 } else { 1105 error_f("unsupported constraint \"%s\"", ext_name); 1106 r = SSH_ERR_FEATURE_UNSUPPORTED; 1107 goto out; 1108 } 1109 /* success */ 1110 r = 0; 1111 out: 1112 free(ext_name); 1113 sshbuf_free(b); 1114 return r; 1115 } 1116 1117 static int 1118 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1119 u_int *secondsp, int *confirmp, char **sk_providerp, 1120 struct dest_constraint **dcsp, size_t *ndcsp) 1121 { 1122 u_char ctype; 1123 int r; 1124 u_int seconds, maxsign = 0; 1125 1126 while (sshbuf_len(m)) { 1127 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1128 error_fr(r, "parse constraint type"); 1129 goto out; 1130 } 1131 switch (ctype) { 1132 case SSH_AGENT_CONSTRAIN_LIFETIME: 1133 if (*deathp != 0) { 1134 error_f("lifetime already set"); 1135 r = SSH_ERR_INVALID_FORMAT; 1136 goto out; 1137 } 1138 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1139 error_fr(r, "parse lifetime constraint"); 1140 goto out; 1141 } 1142 *deathp = monotime() + seconds; 1143 *secondsp = seconds; 1144 break; 1145 case SSH_AGENT_CONSTRAIN_CONFIRM: 1146 if (*confirmp != 0) { 1147 error_f("confirm already set"); 1148 r = SSH_ERR_INVALID_FORMAT; 1149 goto out; 1150 } 1151 *confirmp = 1; 1152 break; 1153 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1154 if (k == NULL) { 1155 error_f("maxsign not valid here"); 1156 r = SSH_ERR_INVALID_FORMAT; 1157 goto out; 1158 } 1159 if (maxsign != 0) { 1160 error_f("maxsign already set"); 1161 r = SSH_ERR_INVALID_FORMAT; 1162 goto out; 1163 } 1164 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1165 error_fr(r, "parse maxsign constraint"); 1166 goto out; 1167 } 1168 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1169 error_fr(r, "enable maxsign"); 1170 goto out; 1171 } 1172 break; 1173 case SSH_AGENT_CONSTRAIN_EXTENSION: 1174 if ((r = parse_key_constraint_extension(m, 1175 sk_providerp, dcsp, ndcsp)) != 0) 1176 goto out; /* error already logged */ 1177 break; 1178 default: 1179 error_f("Unknown constraint %d", ctype); 1180 r = SSH_ERR_FEATURE_UNSUPPORTED; 1181 goto out; 1182 } 1183 } 1184 /* success */ 1185 r = 0; 1186 out: 1187 return r; 1188 } 1189 1190 static void 1191 process_add_identity(SocketEntry *e) 1192 { 1193 Identity *id; 1194 int success = 0, confirm = 0; 1195 char *fp, *comment = NULL, *sk_provider = NULL; 1196 char canonical_provider[PATH_MAX]; 1197 time_t death = 0; 1198 u_int seconds = 0; 1199 struct dest_constraint *dest_constraints = NULL; 1200 size_t ndest_constraints = 0; 1201 struct sshkey *k = NULL; 1202 int r = SSH_ERR_INTERNAL_ERROR; 1203 1204 debug2_f("entering"); 1205 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1206 k == NULL || 1207 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1208 error_fr(r, "parse"); 1209 goto out; 1210 } 1211 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1212 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1213 error_f("failed to parse constraints"); 1214 sshbuf_reset(e->request); 1215 goto out; 1216 } 1217 1218 if (sk_provider != NULL) { 1219 if (!sshkey_is_sk(k)) { 1220 error("Cannot add provider: %s is not an " 1221 "authenticator-hosted key", sshkey_type(k)); 1222 goto out; 1223 } 1224 if (strcasecmp(sk_provider, "internal") == 0) { 1225 debug_f("internal provider"); 1226 } else { 1227 if (realpath(sk_provider, canonical_provider) == NULL) { 1228 verbose("failed provider \"%.100s\": " 1229 "realpath: %s", sk_provider, 1230 strerror(errno)); 1231 goto out; 1232 } 1233 free(sk_provider); 1234 sk_provider = xstrdup(canonical_provider); 1235 if (match_pattern_list(sk_provider, 1236 allowed_providers, 0) != 1) { 1237 error("Refusing add key: " 1238 "provider %s not allowed", sk_provider); 1239 goto out; 1240 } 1241 } 1242 } 1243 if ((r = sshkey_shield_private(k)) != 0) { 1244 error_fr(r, "shield private"); 1245 goto out; 1246 } 1247 if (lifetime && !death) 1248 death = monotime() + lifetime; 1249 if ((id = lookup_identity(k)) == NULL) { 1250 id = xcalloc(1, sizeof(Identity)); 1251 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1252 /* Increment the number of identities. */ 1253 idtab->nentries++; 1254 } else { 1255 /* identity not visible, do not update */ 1256 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1257 goto out; /* error already logged */ 1258 /* key state might have been updated */ 1259 sshkey_free(id->key); 1260 free(id->comment); 1261 free(id->sk_provider); 1262 free_dest_constraints(id->dest_constraints, 1263 id->ndest_constraints); 1264 } 1265 /* success */ 1266 id->key = k; 1267 id->comment = comment; 1268 id->death = death; 1269 id->confirm = confirm; 1270 id->sk_provider = sk_provider; 1271 id->dest_constraints = dest_constraints; 1272 id->ndest_constraints = ndest_constraints; 1273 1274 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1275 SSH_FP_DEFAULT)) == NULL) 1276 fatal_f("sshkey_fingerprint failed"); 1277 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1278 "(provider: %s) (destination constraints: %zu)", 1279 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1280 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1281 free(fp); 1282 /* transferred */ 1283 k = NULL; 1284 comment = NULL; 1285 sk_provider = NULL; 1286 dest_constraints = NULL; 1287 ndest_constraints = 0; 1288 success = 1; 1289 out: 1290 free(sk_provider); 1291 free(comment); 1292 sshkey_free(k); 1293 free_dest_constraints(dest_constraints, ndest_constraints); 1294 send_status(e, success); 1295 } 1296 1297 /* XXX todo: encrypt sensitive data with passphrase */ 1298 static void 1299 process_lock_agent(SocketEntry *e, int lock) 1300 { 1301 int r, success = 0, delay; 1302 char *passwd; 1303 u_char passwdhash[LOCK_SIZE]; 1304 static u_int fail_count = 0; 1305 size_t pwlen; 1306 1307 debug2_f("entering"); 1308 /* 1309 * This is deliberately fatal: the user has requested that we lock, 1310 * but we can't parse their request properly. The only safe thing to 1311 * do is abort. 1312 */ 1313 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1314 fatal_fr(r, "parse"); 1315 if (pwlen == 0) { 1316 debug("empty password not supported"); 1317 } else if (locked && !lock) { 1318 if (bcrypt_pbkdf(passwd, pwlen, (uint8_t *)lock_salt, sizeof(lock_salt), 1319 (uint8_t *)passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1320 fatal("bcrypt_pbkdf"); 1321 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1322 debug("agent unlocked"); 1323 locked = 0; 1324 fail_count = 0; 1325 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1326 success = 1; 1327 } else { 1328 /* delay in 0.1s increments up to 10s */ 1329 if (fail_count < 100) 1330 fail_count++; 1331 delay = 100000 * fail_count; 1332 debug("unlock failed, delaying %0.1lf seconds", 1333 (double)delay/1000000); 1334 usleep(delay); 1335 } 1336 explicit_bzero(passwdhash, sizeof(passwdhash)); 1337 } else if (!locked && lock) { 1338 debug("agent locked"); 1339 locked = 1; 1340 arc4random_buf(lock_salt, sizeof(lock_salt)); 1341 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1342 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1343 fatal("bcrypt_pbkdf"); 1344 success = 1; 1345 } 1346 freezero(passwd, pwlen); 1347 send_status(e, success); 1348 } 1349 1350 static void 1351 no_identities(SocketEntry *e) 1352 { 1353 struct sshbuf *msg; 1354 int r; 1355 1356 if ((msg = sshbuf_new()) == NULL) 1357 fatal_f("sshbuf_new failed"); 1358 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1359 (r = sshbuf_put_u32(msg, 0)) != 0 || 1360 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1361 fatal_fr(r, "compose"); 1362 sshbuf_free(msg); 1363 } 1364 1365 #ifdef ENABLE_PKCS11 1366 static void 1367 process_add_smartcard_key(SocketEntry *e) 1368 { 1369 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1370 char **comments = NULL; 1371 int r, i, count = 0, success = 0, confirm = 0; 1372 u_int seconds = 0; 1373 time_t death = 0; 1374 struct sshkey **keys = NULL, *k; 1375 Identity *id; 1376 struct dest_constraint *dest_constraints = NULL; 1377 size_t ndest_constraints = 0; 1378 1379 debug2_f("entering"); 1380 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1381 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1382 error_fr(r, "parse"); 1383 goto send; 1384 } 1385 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1386 NULL, &dest_constraints, &ndest_constraints) != 0) { 1387 error_f("failed to parse constraints"); 1388 goto send; 1389 } 1390 if (realpath(provider, canonical_provider) == NULL) { 1391 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1392 provider, strerror(errno)); 1393 goto send; 1394 } 1395 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1396 verbose("refusing PKCS#11 add of \"%.100s\": " 1397 "provider not allowed", canonical_provider); 1398 goto send; 1399 } 1400 debug_f("add %.100s", canonical_provider); 1401 if (lifetime && !death) 1402 death = monotime() + lifetime; 1403 1404 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1405 for (i = 0; i < count; i++) { 1406 k = keys[i]; 1407 if (lookup_identity(k) == NULL) { 1408 id = xcalloc(1, sizeof(Identity)); 1409 id->key = k; 1410 keys[i] = NULL; /* transferred */ 1411 id->provider = xstrdup(canonical_provider); 1412 if (*comments[i] != '\0') { 1413 id->comment = comments[i]; 1414 comments[i] = NULL; /* transferred */ 1415 } else { 1416 id->comment = xstrdup(canonical_provider); 1417 } 1418 id->death = death; 1419 id->confirm = confirm; 1420 id->dest_constraints = dest_constraints; 1421 id->ndest_constraints = ndest_constraints; 1422 dest_constraints = NULL; /* transferred */ 1423 ndest_constraints = 0; 1424 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1425 idtab->nentries++; 1426 success = 1; 1427 } 1428 /* XXX update constraints for existing keys */ 1429 sshkey_free(keys[i]); 1430 free(comments[i]); 1431 } 1432 send: 1433 free(pin); 1434 free(provider); 1435 free(keys); 1436 free(comments); 1437 free_dest_constraints(dest_constraints, ndest_constraints); 1438 send_status(e, success); 1439 } 1440 1441 static void 1442 process_remove_smartcard_key(SocketEntry *e) 1443 { 1444 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1445 int r, success = 0; 1446 Identity *id, *nxt; 1447 1448 debug2_f("entering"); 1449 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1450 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1451 error_fr(r, "parse"); 1452 goto send; 1453 } 1454 free(pin); 1455 1456 if (realpath(provider, canonical_provider) == NULL) { 1457 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1458 provider, strerror(errno)); 1459 goto send; 1460 } 1461 1462 debug_f("remove %.100s", canonical_provider); 1463 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1464 nxt = TAILQ_NEXT(id, next); 1465 /* Skip file--based keys */ 1466 if (id->provider == NULL) 1467 continue; 1468 if (!strcmp(canonical_provider, id->provider)) { 1469 TAILQ_REMOVE(&idtab->idlist, id, next); 1470 free_identity(id); 1471 idtab->nentries--; 1472 } 1473 } 1474 if (pkcs11_del_provider(canonical_provider) == 0) 1475 success = 1; 1476 else 1477 error_f("pkcs11_del_provider failed"); 1478 send: 1479 free(provider); 1480 send_status(e, success); 1481 } 1482 #endif /* ENABLE_PKCS11 */ 1483 1484 static int 1485 process_ext_session_bind(SocketEntry *e) 1486 { 1487 int r, sid_match, key_match; 1488 struct sshkey *key = NULL; 1489 struct sshbuf *sid = NULL, *sig = NULL; 1490 char *fp = NULL; 1491 size_t i; 1492 u_char fwd = 0; 1493 1494 debug2_f("entering"); 1495 if ((r = sshkey_froms(e->request, &key)) != 0 || 1496 (r = sshbuf_froms(e->request, &sid)) != 0 || 1497 (r = sshbuf_froms(e->request, &sig)) != 0 || 1498 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1499 error_fr(r, "parse"); 1500 goto out; 1501 } 1502 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1503 SSH_FP_DEFAULT)) == NULL) 1504 fatal_f("fingerprint failed"); 1505 /* check signature with hostkey on session ID */ 1506 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1507 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1508 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1509 goto out; 1510 } 1511 /* check whether sid/key already recorded */ 1512 for (i = 0; i < e->nsession_ids; i++) { 1513 if (!e->session_ids[i].forwarded) { 1514 error_f("attempt to bind session ID to socket " 1515 "previously bound for authentication attempt"); 1516 r = -1; 1517 goto out; 1518 } 1519 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1520 key_match = sshkey_equal(key, e->session_ids[i].key); 1521 if (sid_match && key_match) { 1522 debug_f("session ID already recorded for %s %s", 1523 sshkey_type(key), fp); 1524 r = 0; 1525 goto out; 1526 } else if (sid_match) { 1527 error_f("session ID recorded against different key " 1528 "for %s %s", sshkey_type(key), fp); 1529 r = -1; 1530 goto out; 1531 } 1532 /* 1533 * new sid with previously-seen key can happen, e.g. multiple 1534 * connections to the same host. 1535 */ 1536 } 1537 /* record new key/sid */ 1538 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1539 error_f("too many session IDs recorded"); 1540 goto out; 1541 } 1542 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1543 e->nsession_ids + 1, sizeof(*e->session_ids)); 1544 i = e->nsession_ids++; 1545 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1546 AGENT_MAX_SESSION_IDS); 1547 e->session_ids[i].key = key; 1548 e->session_ids[i].forwarded = fwd != 0; 1549 key = NULL; /* transferred */ 1550 /* can't transfer sid; it's refcounted and scoped to request's life */ 1551 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1552 fatal_f("sshbuf_new"); 1553 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1554 fatal_fr(r, "sshbuf_putb session ID"); 1555 /* success */ 1556 r = 0; 1557 out: 1558 free(fp); 1559 sshkey_free(key); 1560 sshbuf_free(sid); 1561 sshbuf_free(sig); 1562 return r == 0 ? 1 : 0; 1563 } 1564 1565 static void 1566 process_extension(SocketEntry *e) 1567 { 1568 int r, success = 0; 1569 char *name; 1570 1571 debug2_f("entering"); 1572 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1573 error_fr(r, "parse"); 1574 goto send; 1575 } 1576 if (strcmp(name, "session-bind@openssh.com") == 0) 1577 success = process_ext_session_bind(e); 1578 else 1579 debug_f("unsupported extension \"%s\"", name); 1580 free(name); 1581 send: 1582 send_status(e, success); 1583 } 1584 /* 1585 * dispatch incoming message. 1586 * returns 1 on success, 0 for incomplete messages or -1 on error. 1587 */ 1588 static int 1589 process_message(u_int socknum) 1590 { 1591 u_int msg_len; 1592 u_char type; 1593 const u_char *cp; 1594 int r; 1595 SocketEntry *e; 1596 1597 if (socknum >= sockets_alloc) 1598 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1599 e = &sockets[socknum]; 1600 1601 if (sshbuf_len(e->input) < 5) 1602 return 0; /* Incomplete message header. */ 1603 cp = sshbuf_ptr(e->input); 1604 msg_len = PEEK_U32(cp); 1605 if (msg_len > AGENT_MAX_LEN) { 1606 debug_f("socket %u (fd=%d) message too long %u > %u", 1607 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1608 return -1; 1609 } 1610 if (sshbuf_len(e->input) < msg_len + 4) 1611 return 0; /* Incomplete message body. */ 1612 1613 /* move the current input to e->request */ 1614 sshbuf_reset(e->request); 1615 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1616 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1617 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1618 r == SSH_ERR_STRING_TOO_LARGE) { 1619 error_fr(r, "parse"); 1620 return -1; 1621 } 1622 fatal_fr(r, "parse"); 1623 } 1624 1625 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1626 1627 /* check whether agent is locked */ 1628 if (locked && type != SSH_AGENTC_UNLOCK) { 1629 sshbuf_reset(e->request); 1630 switch (type) { 1631 case SSH2_AGENTC_REQUEST_IDENTITIES: 1632 /* send empty lists */ 1633 no_identities(e); 1634 break; 1635 default: 1636 /* send a fail message for all other request types */ 1637 send_status(e, 0); 1638 } 1639 return 1; 1640 } 1641 1642 switch (type) { 1643 case SSH_AGENTC_LOCK: 1644 case SSH_AGENTC_UNLOCK: 1645 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1646 break; 1647 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1648 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1649 break; 1650 /* ssh2 */ 1651 case SSH2_AGENTC_SIGN_REQUEST: 1652 process_sign_request2(e); 1653 break; 1654 case SSH2_AGENTC_REQUEST_IDENTITIES: 1655 process_request_identities(e); 1656 break; 1657 case SSH2_AGENTC_ADD_IDENTITY: 1658 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1659 process_add_identity(e); 1660 break; 1661 case SSH2_AGENTC_REMOVE_IDENTITY: 1662 process_remove_identity(e); 1663 break; 1664 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1665 process_remove_all_identities(e); 1666 break; 1667 #ifdef ENABLE_PKCS11 1668 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1669 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1670 process_add_smartcard_key(e); 1671 break; 1672 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1673 process_remove_smartcard_key(e); 1674 break; 1675 #endif /* ENABLE_PKCS11 */ 1676 case SSH_AGENTC_EXTENSION: 1677 process_extension(e); 1678 break; 1679 default: 1680 /* Unknown message. Respond with failure. */ 1681 error("Unknown message %d", type); 1682 sshbuf_reset(e->request); 1683 send_status(e, 0); 1684 break; 1685 } 1686 return 1; 1687 } 1688 1689 static void 1690 new_socket(sock_type type, int fd) 1691 { 1692 u_int i, old_alloc, new_alloc; 1693 1694 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1695 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1696 set_nonblock(fd); 1697 1698 if (fd > max_fd) 1699 max_fd = fd; 1700 1701 for (i = 0; i < sockets_alloc; i++) 1702 if (sockets[i].type == AUTH_UNUSED) { 1703 sockets[i].fd = fd; 1704 if ((sockets[i].input = sshbuf_new()) == NULL || 1705 (sockets[i].output = sshbuf_new()) == NULL || 1706 (sockets[i].request = sshbuf_new()) == NULL) 1707 fatal_f("sshbuf_new failed"); 1708 sockets[i].type = type; 1709 return; 1710 } 1711 old_alloc = sockets_alloc; 1712 new_alloc = sockets_alloc + 10; 1713 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1714 sizeof(sockets[0])); 1715 for (i = old_alloc; i < new_alloc; i++) 1716 sockets[i].type = AUTH_UNUSED; 1717 sockets_alloc = new_alloc; 1718 sockets[old_alloc].fd = fd; 1719 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1720 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1721 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1722 fatal_f("sshbuf_new failed"); 1723 sockets[old_alloc].type = type; 1724 } 1725 1726 static int 1727 handle_socket_read(u_int socknum) 1728 { 1729 struct sockaddr_un sunaddr; 1730 socklen_t slen; 1731 uid_t euid; 1732 gid_t egid; 1733 int fd; 1734 1735 slen = sizeof(sunaddr); 1736 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1737 if (fd == -1) { 1738 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1739 return -1; 1740 } 1741 if (getpeereid(fd, &euid, &egid) == -1) { 1742 error("getpeereid %d failed: %s", fd, strerror(errno)); 1743 close(fd); 1744 return -1; 1745 } 1746 if ((euid != 0) && (getuid() != euid)) { 1747 error("uid mismatch: peer euid %u != uid %u", 1748 (u_int) euid, (u_int) getuid()); 1749 close(fd); 1750 return -1; 1751 } 1752 new_socket(AUTH_CONNECTION, fd); 1753 return 0; 1754 } 1755 1756 static int 1757 handle_conn_read(u_int socknum) 1758 { 1759 char buf[AGENT_RBUF_LEN]; 1760 ssize_t len; 1761 int r; 1762 1763 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1764 if (len == -1) { 1765 if (errno == EAGAIN || errno == EINTR) 1766 return 0; 1767 error_f("read error on socket %u (fd %d): %s", 1768 socknum, sockets[socknum].fd, strerror(errno)); 1769 } 1770 return -1; 1771 } 1772 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1773 fatal_fr(r, "compose"); 1774 explicit_bzero(buf, sizeof(buf)); 1775 for (;;) { 1776 if ((r = process_message(socknum)) == -1) 1777 return -1; 1778 else if (r == 0) 1779 break; 1780 } 1781 return 0; 1782 } 1783 1784 static int 1785 handle_conn_write(u_int socknum) 1786 { 1787 ssize_t len; 1788 int r; 1789 1790 if (sshbuf_len(sockets[socknum].output) == 0) 1791 return 0; /* shouldn't happen */ 1792 if ((len = write(sockets[socknum].fd, 1793 sshbuf_ptr(sockets[socknum].output), 1794 sshbuf_len(sockets[socknum].output))) <= 0) { 1795 if (len == -1) { 1796 if (errno == EAGAIN || errno == EINTR) 1797 return 0; 1798 error_f("read error on socket %u (fd %d): %s", 1799 socknum, sockets[socknum].fd, strerror(errno)); 1800 } 1801 return -1; 1802 } 1803 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1804 fatal_fr(r, "consume"); 1805 return 0; 1806 } 1807 1808 static void 1809 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1810 { 1811 size_t i; 1812 u_int socknum, activefds = npfd; 1813 1814 for (i = 0; i < npfd; i++) { 1815 if (pfd[i].revents == 0) 1816 continue; 1817 /* Find sockets entry */ 1818 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1819 if (sockets[socknum].type != AUTH_SOCKET && 1820 sockets[socknum].type != AUTH_CONNECTION) 1821 continue; 1822 if (pfd[i].fd == sockets[socknum].fd) 1823 break; 1824 } 1825 if (socknum >= sockets_alloc) { 1826 error_f("no socket for fd %d", pfd[i].fd); 1827 continue; 1828 } 1829 /* Process events */ 1830 switch (sockets[socknum].type) { 1831 case AUTH_SOCKET: 1832 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1833 break; 1834 if (npfd > maxfds) { 1835 debug3("out of fds (active %u >= limit %u); " 1836 "skipping accept", activefds, maxfds); 1837 break; 1838 } 1839 if (handle_socket_read(socknum) == 0) 1840 activefds++; 1841 break; 1842 case AUTH_CONNECTION: 1843 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1844 handle_conn_read(socknum) != 0) 1845 goto close_sock; 1846 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1847 handle_conn_write(socknum) != 0) { 1848 close_sock: 1849 if (activefds == 0) 1850 fatal("activefds == 0 at close_sock"); 1851 close_socket(&sockets[socknum]); 1852 activefds--; 1853 break; 1854 } 1855 break; 1856 default: 1857 break; 1858 } 1859 } 1860 } 1861 1862 static int 1863 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1864 { 1865 struct pollfd *pfd = *pfdp; 1866 size_t i, j, npfd = 0; 1867 time_t deadline; 1868 int r; 1869 1870 /* Count active sockets */ 1871 for (i = 0; i < sockets_alloc; i++) { 1872 switch (sockets[i].type) { 1873 case AUTH_SOCKET: 1874 case AUTH_CONNECTION: 1875 npfd++; 1876 break; 1877 case AUTH_UNUSED: 1878 break; 1879 default: 1880 fatal("Unknown socket type %d", sockets[i].type); 1881 break; 1882 } 1883 } 1884 if (npfd != *npfdp && 1885 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1886 fatal_f("recallocarray failed"); 1887 *pfdp = pfd; 1888 *npfdp = npfd; 1889 1890 for (i = j = 0; i < sockets_alloc; i++) { 1891 switch (sockets[i].type) { 1892 case AUTH_SOCKET: 1893 if (npfd > maxfds) { 1894 debug3("out of fds (active %zu >= limit %u); " 1895 "skipping arming listener", npfd, maxfds); 1896 break; 1897 } 1898 pfd[j].fd = sockets[i].fd; 1899 pfd[j].revents = 0; 1900 pfd[j].events = POLLIN; 1901 j++; 1902 break; 1903 case AUTH_CONNECTION: 1904 pfd[j].fd = sockets[i].fd; 1905 pfd[j].revents = 0; 1906 /* 1907 * Only prepare to read if we can handle a full-size 1908 * input read buffer and enqueue a max size reply.. 1909 */ 1910 if ((r = sshbuf_check_reserve(sockets[i].input, 1911 AGENT_RBUF_LEN)) == 0 && 1912 (r = sshbuf_check_reserve(sockets[i].output, 1913 AGENT_MAX_LEN)) == 0) 1914 pfd[j].events = POLLIN; 1915 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1916 fatal_fr(r, "reserve"); 1917 if (sshbuf_len(sockets[i].output) > 0) 1918 pfd[j].events |= POLLOUT; 1919 j++; 1920 break; 1921 default: 1922 break; 1923 } 1924 } 1925 deadline = reaper(); 1926 if (parent_alive_interval != 0) 1927 deadline = (deadline == 0) ? parent_alive_interval : 1928 MINIMUM(deadline, parent_alive_interval); 1929 if (deadline == 0) { 1930 *timeoutp = -1; /* INFTIM */ 1931 } else { 1932 if (deadline > INT_MAX / 1000) 1933 *timeoutp = INT_MAX / 1000; 1934 else 1935 *timeoutp = deadline * 1000; 1936 } 1937 return (1); 1938 } 1939 1940 static void 1941 cleanup_socket(void) 1942 { 1943 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1944 return; 1945 debug_f("cleanup"); 1946 if (socket_name[0]) 1947 unlink(socket_name); 1948 if (socket_dir[0]) 1949 rmdir(socket_dir); 1950 } 1951 1952 void 1953 cleanup_exit(int i) 1954 { 1955 cleanup_socket(); 1956 _exit(i); 1957 } 1958 1959 /*ARGSUSED*/ 1960 __dead static void 1961 cleanup_handler(int sig) 1962 { 1963 cleanup_socket(); 1964 #ifdef ENABLE_PKCS11 1965 pkcs11_terminate(); 1966 #endif 1967 _exit(2); 1968 } 1969 1970 static void 1971 check_parent_exists(void) 1972 { 1973 /* 1974 * If our parent has exited then getppid() will return (pid_t)1, 1975 * so testing for that should be safe. 1976 */ 1977 if (parent_pid != -1 && getppid() != parent_pid) { 1978 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1979 cleanup_socket(); 1980 _exit(2); 1981 } 1982 } 1983 1984 __dead static void 1985 usage(void) 1986 { 1987 fprintf(stderr, 1988 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1989 " [-P allowed_providers] [-t life]\n" 1990 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1991 " [-t life] command [arg ...]\n" 1992 " ssh-agent [-c | -s] -k\n"); 1993 exit(1); 1994 } 1995 1996 static void 1997 csh_setenv(const char *name, const char *value) 1998 { 1999 printf("setenv %s %s;\n", name, value); 2000 } 2001 2002 static void 2003 csh_unsetenv(const char *name) 2004 { 2005 printf("unsetenv %s;\n", name); 2006 } 2007 2008 static void 2009 sh_setenv(const char *name, const char *value) 2010 { 2011 printf("%s=%s; export %s;\n", name, value, name); 2012 } 2013 2014 static void 2015 sh_unsetenv(const char *name) 2016 { 2017 printf("unset %s;\n", name); 2018 } 2019 int 2020 main(int ac, char **av) 2021 { 2022 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2023 int sock, ch, result, saved_errno; 2024 char *shell, *pidstr, *agentsocket = NULL; 2025 struct rlimit rlim; 2026 void (*f_setenv)(const char *, const char *); 2027 void (*f_unsetenv)(const char *); 2028 extern int optind; 2029 extern char *optarg; 2030 pid_t pid; 2031 char pidstrbuf[1 + 3 * sizeof pid]; 2032 size_t len; 2033 mode_t prev_mask; 2034 int timeout = -1; /* INFTIM */ 2035 struct pollfd *pfd = NULL; 2036 size_t npfd = 0; 2037 u_int maxfds; 2038 2039 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2040 sanitise_stdfd(); 2041 2042 /* drop */ 2043 setegid(getgid()); 2044 setgid(getgid()); 2045 2046 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2047 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2048 2049 #ifdef WITH_OPENSSL 2050 OpenSSL_add_all_algorithms(); 2051 #endif 2052 2053 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2054 switch (ch) { 2055 case 'E': 2056 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2057 if (fingerprint_hash == -1) 2058 fatal("Invalid hash algorithm \"%s\"", optarg); 2059 break; 2060 case 'c': 2061 if (s_flag) 2062 usage(); 2063 c_flag++; 2064 break; 2065 case 'k': 2066 k_flag++; 2067 break; 2068 case 'O': 2069 if (strcmp(optarg, "no-restrict-websafe") == 0) 2070 restrict_websafe = 0; 2071 else 2072 fatal("Unknown -O option"); 2073 break; 2074 case 'P': 2075 if (allowed_providers != NULL) 2076 fatal("-P option already specified"); 2077 allowed_providers = xstrdup(optarg); 2078 break; 2079 case 's': 2080 if (c_flag) 2081 usage(); 2082 s_flag++; 2083 break; 2084 case 'd': 2085 if (d_flag || D_flag) 2086 usage(); 2087 d_flag++; 2088 break; 2089 case 'D': 2090 if (d_flag || D_flag) 2091 usage(); 2092 D_flag++; 2093 break; 2094 case 'a': 2095 agentsocket = optarg; 2096 break; 2097 case 't': 2098 if ((lifetime = convtime(optarg)) == -1) { 2099 fprintf(stderr, "Invalid lifetime\n"); 2100 usage(); 2101 } 2102 break; 2103 default: 2104 usage(); 2105 } 2106 } 2107 ac -= optind; 2108 av += optind; 2109 2110 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2111 usage(); 2112 2113 if (allowed_providers == NULL) 2114 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2115 2116 if (ac == 0 && !c_flag && !s_flag) { 2117 shell = getenv("SHELL"); 2118 if (shell != NULL && (len = strlen(shell)) > 2 && 2119 strncmp(shell + len - 3, "csh", 3) == 0) 2120 c_flag = 1; 2121 } 2122 if (c_flag) { 2123 f_setenv = csh_setenv; 2124 f_unsetenv = csh_unsetenv; 2125 } else { 2126 f_setenv = sh_setenv; 2127 f_unsetenv = sh_unsetenv; 2128 } 2129 if (k_flag) { 2130 const char *errstr = NULL; 2131 2132 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2133 if (pidstr == NULL) { 2134 fprintf(stderr, "%s not set, cannot kill agent\n", 2135 SSH_AGENTPID_ENV_NAME); 2136 exit(1); 2137 } 2138 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2139 if (errstr) { 2140 fprintf(stderr, 2141 "%s=\"%s\", which is not a good PID: %s\n", 2142 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2143 exit(1); 2144 } 2145 if (kill(pid, SIGTERM) == -1) { 2146 perror("kill"); 2147 exit(1); 2148 } 2149 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 2150 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 2151 printf("echo Agent pid %ld killed;\n", (long)pid); 2152 exit(0); 2153 } 2154 2155 /* 2156 * Minimum file descriptors: 2157 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2158 * a few spare for libc / stack protectors / sanitisers, etc. 2159 */ 2160 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2161 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2162 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2163 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2164 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2165 2166 parent_pid = getpid(); 2167 2168 if (agentsocket == NULL) { 2169 /* Create private directory for agent socket */ 2170 mktemp_proto(socket_dir, sizeof(socket_dir)); 2171 if (mkdtemp(socket_dir) == NULL) { 2172 perror("mkdtemp: private socket dir"); 2173 exit(1); 2174 } 2175 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2176 (long)parent_pid); 2177 } else { 2178 /* Try to use specified agent socket */ 2179 socket_dir[0] = '\0'; 2180 strlcpy(socket_name, agentsocket, sizeof socket_name); 2181 } 2182 2183 /* 2184 * Create socket early so it will exist before command gets run from 2185 * the parent. 2186 */ 2187 prev_mask = umask(0177); 2188 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2189 if (sock < 0) { 2190 /* XXX - unix_listener() calls error() not perror() */ 2191 *socket_name = '\0'; /* Don't unlink any existing file */ 2192 cleanup_exit(1); 2193 } 2194 umask(prev_mask); 2195 2196 /* 2197 * Fork, and have the parent execute the command, if any, or present 2198 * the socket data. The child continues as the authentication agent. 2199 */ 2200 if (D_flag || d_flag) { 2201 log_init(__progname, 2202 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2203 SYSLOG_FACILITY_AUTH, 1); 2204 if (c_flag) 2205 printf("setenv %s %s;\n", 2206 SSH_AUTHSOCKET_ENV_NAME, socket_name); 2207 else 2208 printf("%s=%s; export %s;\n", 2209 SSH_AUTHSOCKET_ENV_NAME, socket_name, 2210 SSH_AUTHSOCKET_ENV_NAME); 2211 printf("echo Agent pid %ld;\n", (long)parent_pid); 2212 fflush(stdout); 2213 goto skip; 2214 } 2215 pid = fork(); 2216 if (pid == -1) { 2217 perror("fork"); 2218 cleanup_exit(1); 2219 } 2220 if (pid != 0) { /* Parent - execute the given command. */ 2221 close(sock); 2222 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2223 if (ac == 0) { 2224 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 2225 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 2226 printf("echo Agent pid %ld;\n", (long)pid); 2227 exit(0); 2228 } 2229 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2230 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2231 perror("setenv"); 2232 exit(1); 2233 } 2234 execvp(av[0], av); 2235 perror(av[0]); 2236 exit(1); 2237 } 2238 /* child */ 2239 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2240 2241 if (setsid() == -1) { 2242 error("setsid: %s", strerror(errno)); 2243 cleanup_exit(1); 2244 } 2245 2246 (void)chdir("/"); 2247 if (stdfd_devnull(1, 1, 1) == -1) 2248 error_f("stdfd_devnull failed"); 2249 2250 /* deny core dumps, since memory contains unencrypted private keys */ 2251 rlim.rlim_cur = rlim.rlim_max = 0; 2252 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2253 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2254 cleanup_exit(1); 2255 } 2256 2257 skip: 2258 2259 cleanup_pid = getpid(); 2260 2261 #ifdef ENABLE_PKCS11 2262 pkcs11_init(0); 2263 #endif 2264 new_socket(AUTH_SOCKET, sock); 2265 if (ac > 0) 2266 parent_alive_interval = 10; 2267 idtab_init(); 2268 ssh_signal(SIGPIPE, SIG_IGN); 2269 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2270 ssh_signal(SIGHUP, cleanup_handler); 2271 ssh_signal(SIGTERM, cleanup_handler); 2272 2273 #ifdef __OpenBSD__ 2274 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2275 fatal("%s: pledge: %s", __progname, strerror(errno)); 2276 #endif 2277 2278 while (1) { 2279 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2280 result = poll(pfd, npfd, timeout); 2281 saved_errno = errno; 2282 if (parent_alive_interval != 0) 2283 check_parent_exists(); 2284 (void) reaper(); /* remove expired keys */ 2285 if (result == -1) { 2286 if (saved_errno == EINTR) 2287 continue; 2288 fatal("poll: %s", strerror(saved_errno)); 2289 } else if (result > 0) 2290 after_poll(pfd, npfd, maxfds); 2291 } 2292 /* NOTREACHED */ 2293 } 2294