1 /* $NetBSD: ssh-agent.c,v 1.36 2023/10/25 20:19:57 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.300 2023/07/19 13:56:33 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 1.36 2023/10/25 20:19:57 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 "log.h" 77 #include "misc.h" 78 #include "getpeereid.h" 79 #include "digest.h" 80 #include "ssherr.h" 81 #include "match.h" 82 #include "msg.h" 83 #include "pathnames.h" 84 #include "ssh-pkcs11.h" 85 #include "sk-api.h" 86 #include "myproposal.h" 87 88 #ifndef DEFAULT_ALLOWED_PROVIDERS 89 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/pkg/lib*/*" 90 #endif 91 92 /* Maximum accepted message length */ 93 #define AGENT_MAX_LEN (256*1024) 94 /* Maximum bytes to read from client socket */ 95 #define AGENT_RBUF_LEN (4096) 96 /* Maximum number of recorded session IDs/hostkeys per connection */ 97 #define AGENT_MAX_SESSION_IDS 16 98 /* Maximum size of session ID */ 99 #define AGENT_MAX_SID_LEN 128 100 /* Maximum number of destination constraints to accept on a key */ 101 #define AGENT_MAX_DEST_CONSTRAINTS 1024 102 103 /* XXX store hostkey_sid in a refcounted tree */ 104 105 typedef enum { 106 AUTH_UNUSED = 0, 107 AUTH_SOCKET = 1, 108 AUTH_CONNECTION = 2, 109 } sock_type; 110 111 struct hostkey_sid { 112 struct sshkey *key; 113 struct sshbuf *sid; 114 int forwarded; 115 }; 116 117 typedef struct socket_entry { 118 int fd; 119 sock_type type; 120 struct sshbuf *input; 121 struct sshbuf *output; 122 struct sshbuf *request; 123 size_t nsession_ids; 124 struct hostkey_sid *session_ids; 125 } SocketEntry; 126 127 u_int sockets_alloc = 0; 128 SocketEntry *sockets = NULL; 129 130 typedef struct identity { 131 TAILQ_ENTRY(identity) next; 132 struct sshkey *key; 133 char *comment; 134 char *provider; 135 time_t death; 136 u_int confirm; 137 char *sk_provider; 138 struct dest_constraint *dest_constraints; 139 size_t ndest_constraints; 140 } Identity; 141 142 struct idtable { 143 int nentries; 144 TAILQ_HEAD(idqueue, identity) idlist; 145 }; 146 147 /* private key table */ 148 struct idtable *idtab; 149 150 int max_fd = 0; 151 152 /* pid of shell == parent of agent */ 153 pid_t parent_pid = -1; 154 time_t parent_alive_interval = 0; 155 156 /* pid of process for which cleanup_socket is applicable */ 157 pid_t cleanup_pid = 0; 158 159 /* pathname and directory for AUTH_SOCKET */ 160 char socket_name[PATH_MAX]; 161 char socket_dir[PATH_MAX]; 162 163 /* Pattern-list of allowed PKCS#11/Security key paths */ 164 static char *allowed_providers; 165 166 /* 167 * Allows PKCS11 providers or SK keys that use non-internal providers to 168 * be added over a remote connection (identified by session-bind@openssh.com). 169 */ 170 static int remote_add_provider; 171 172 /* locking */ 173 #define LOCK_SIZE 32 174 #define LOCK_SALT_SIZE 16 175 #define LOCK_ROUNDS 1 176 int locked = 0; 177 u_char lock_pwhash[LOCK_SIZE]; 178 u_char lock_salt[LOCK_SALT_SIZE]; 179 180 extern char *__progname; 181 182 /* Default lifetime in seconds (0 == forever) */ 183 static int lifetime = 0; 184 185 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 186 187 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 188 static int restrict_websafe = 1; 189 190 static void 191 close_socket(SocketEntry *e) 192 { 193 size_t i; 194 195 close(e->fd); 196 sshbuf_free(e->input); 197 sshbuf_free(e->output); 198 sshbuf_free(e->request); 199 for (i = 0; i < e->nsession_ids; i++) { 200 sshkey_free(e->session_ids[i].key); 201 sshbuf_free(e->session_ids[i].sid); 202 } 203 free(e->session_ids); 204 memset(e, '\0', sizeof(*e)); 205 e->fd = -1; 206 e->type = AUTH_UNUSED; 207 } 208 209 static void 210 idtab_init(void) 211 { 212 idtab = xcalloc(1, sizeof(*idtab)); 213 TAILQ_INIT(&idtab->idlist); 214 idtab->nentries = 0; 215 } 216 217 static void 218 free_dest_constraint_hop(struct dest_constraint_hop *dch) 219 { 220 u_int i; 221 222 if (dch == NULL) 223 return; 224 free(dch->user); 225 free(dch->hostname); 226 for (i = 0; i < dch->nkeys; i++) 227 sshkey_free(dch->keys[i]); 228 free(dch->keys); 229 free(dch->key_is_ca); 230 } 231 232 static void 233 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 234 { 235 size_t i; 236 237 for (i = 0; i < ndcs; i++) { 238 free_dest_constraint_hop(&dcs[i].from); 239 free_dest_constraint_hop(&dcs[i].to); 240 } 241 free(dcs); 242 } 243 244 static void 245 free_identity(Identity *id) 246 { 247 sshkey_free(id->key); 248 free(id->provider); 249 free(id->comment); 250 free(id->sk_provider); 251 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 252 free(id); 253 } 254 255 /* 256 * Match 'key' against the key/CA list in a destination constraint hop 257 * Returns 0 on success or -1 otherwise. 258 */ 259 static int 260 match_key_hop(const char *tag, const struct sshkey *key, 261 const struct dest_constraint_hop *dch) 262 { 263 const char *reason = NULL; 264 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 265 u_int i; 266 char *fp; 267 268 if (key == NULL) 269 return -1; 270 /* XXX logspam */ 271 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 272 SSH_FP_DEFAULT)) == NULL) 273 fatal_f("fingerprint failed"); 274 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 275 tag, hostname, sshkey_type(key), fp, dch->nkeys); 276 free(fp); 277 for (i = 0; i < dch->nkeys; i++) { 278 if (dch->keys[i] == NULL) 279 return -1; 280 /* XXX logspam */ 281 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 282 SSH_FP_DEFAULT)) == NULL) 283 fatal_f("fingerprint failed"); 284 debug3_f("%s: key %u: %s%s %s", tag, i, 285 dch->key_is_ca[i] ? "CA " : "", 286 sshkey_type(dch->keys[i]), fp); 287 free(fp); 288 if (!sshkey_is_cert(key)) { 289 /* plain key */ 290 if (dch->key_is_ca[i] || 291 !sshkey_equal(key, dch->keys[i])) 292 continue; 293 return 0; 294 } 295 /* certificate */ 296 if (!dch->key_is_ca[i]) 297 continue; 298 if (key->cert == NULL || key->cert->signature_key == NULL) 299 return -1; /* shouldn't happen */ 300 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 301 continue; 302 if (sshkey_cert_check_host(key, hostname, 1, 303 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 304 debug_f("cert %s / hostname %s rejected: %s", 305 key->cert->key_id, hostname, reason); 306 continue; 307 } 308 return 0; 309 } 310 return -1; 311 } 312 313 /* Check destination constraints on an identity against the hostkey/user */ 314 static int 315 permitted_by_dest_constraints(const struct sshkey *fromkey, 316 const struct sshkey *tokey, Identity *id, const char *user, 317 const char **hostnamep) 318 { 319 size_t i; 320 struct dest_constraint *d; 321 322 if (hostnamep != NULL) 323 *hostnamep = NULL; 324 for (i = 0; i < id->ndest_constraints; i++) { 325 d = id->dest_constraints + i; 326 /* XXX remove logspam */ 327 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 328 i, d->from.user ? d->from.user : "", 329 d->from.user ? "@" : "", 330 d->from.hostname ? d->from.hostname : "(ORIGIN)", 331 d->from.nkeys, 332 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 333 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 334 335 /* Match 'from' key */ 336 if (fromkey == NULL) { 337 /* We are matching the first hop */ 338 if (d->from.hostname != NULL || d->from.nkeys != 0) 339 continue; 340 } else if (match_key_hop("from", fromkey, &d->from) != 0) 341 continue; 342 343 /* Match 'to' key */ 344 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 345 continue; 346 347 /* Match user if specified */ 348 if (d->to.user != NULL && user != NULL && 349 !match_pattern(user, d->to.user)) 350 continue; 351 352 /* successfully matched this constraint */ 353 if (hostnamep != NULL) 354 *hostnamep = d->to.hostname; 355 debug2_f("allowed for hostname %s", 356 d->to.hostname == NULL ? "*" : d->to.hostname); 357 return 0; 358 } 359 /* no match */ 360 debug2_f("%s identity \"%s\" not permitted for this destination", 361 sshkey_type(id->key), id->comment); 362 return -1; 363 } 364 365 /* 366 * Check whether hostkeys on a SocketEntry and the optionally specified user 367 * are permitted by the destination constraints on the Identity. 368 * Returns 0 on success or -1 otherwise. 369 */ 370 static int 371 identity_permitted(Identity *id, SocketEntry *e, char *user, 372 const char **forward_hostnamep, const char **last_hostnamep) 373 { 374 size_t i; 375 const char **hp; 376 struct hostkey_sid *hks; 377 const struct sshkey *fromkey = NULL; 378 const char *test_user; 379 char *fp1, *fp2; 380 381 /* XXX remove logspam */ 382 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 383 "%zu constraints", sshkey_type(id->key), id->comment, 384 e->nsession_ids, id->ndest_constraints); 385 if (id->ndest_constraints == 0) 386 return 0; /* unconstrained */ 387 if (e->nsession_ids == 0) 388 return 0; /* local use */ 389 /* 390 * Walk through the hops recorded by session_id and try to find a 391 * constraint that satisfies each. 392 */ 393 for (i = 0; i < e->nsession_ids; i++) { 394 hks = e->session_ids + i; 395 if (hks->key == NULL) 396 fatal_f("internal error: no bound key"); 397 /* XXX remove logspam */ 398 fp1 = fp2 = NULL; 399 if (fromkey != NULL && 400 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 401 SSH_FP_DEFAULT)) == NULL) 402 fatal_f("fingerprint failed"); 403 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 404 SSH_FP_DEFAULT)) == NULL) 405 fatal_f("fingerprint failed"); 406 debug3_f("socketentry fd=%d, entry %zu %s, " 407 "from hostkey %s %s to user %s hostkey %s %s", 408 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 409 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 410 fromkey ? fp1 : "", user ? user : "(ANY)", 411 sshkey_type(hks->key), fp2); 412 free(fp1); 413 free(fp2); 414 /* 415 * Record the hostnames for the initial forwarding and 416 * the final destination. 417 */ 418 hp = NULL; 419 if (i == e->nsession_ids - 1) 420 hp = last_hostnamep; 421 else if (i == 0) 422 hp = forward_hostnamep; 423 /* Special handling for final recorded binding */ 424 test_user = NULL; 425 if (i == e->nsession_ids - 1) { 426 /* Can only check user at final hop */ 427 test_user = user; 428 /* 429 * user is only presented for signature requests. 430 * If this is the case, make sure last binding is not 431 * for a forwarding. 432 */ 433 if (hks->forwarded && user != NULL) { 434 error_f("tried to sign on forwarding hop"); 435 return -1; 436 } 437 } else if (!hks->forwarded) { 438 error_f("tried to forward though signing bind"); 439 return -1; 440 } 441 if (permitted_by_dest_constraints(fromkey, hks->key, id, 442 test_user, hp) != 0) 443 return -1; 444 fromkey = hks->key; 445 } 446 /* 447 * Another special case: if the last bound session ID was for a 448 * forwarding, and this function is not being called to check a sign 449 * request (i.e. no 'user' supplied), then only permit the key if 450 * there is a permission that would allow it to be used at another 451 * destination. This hides keys that are allowed to be used to 452 * authenticate *to* a host but not permitted for *use* beyond it. 453 */ 454 hks = &e->session_ids[e->nsession_ids - 1]; 455 if (hks->forwarded && user == NULL && 456 permitted_by_dest_constraints(hks->key, NULL, id, 457 NULL, NULL) != 0) { 458 debug3_f("key permitted at host but not after"); 459 return -1; 460 } 461 462 /* success */ 463 return 0; 464 } 465 466 /* return matching private key for given public key */ 467 static Identity * 468 lookup_identity(struct sshkey *key) 469 { 470 Identity *id; 471 472 TAILQ_FOREACH(id, &idtab->idlist, next) { 473 if (sshkey_equal(key, id->key)) 474 return (id); 475 } 476 return (NULL); 477 } 478 479 /* Check confirmation of keysign request */ 480 static int 481 confirm_key(Identity *id, const char *extra) 482 { 483 char *p; 484 int ret = -1; 485 486 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 487 if (p != NULL && 488 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 489 id->comment, p, 490 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 491 ret = 0; 492 free(p); 493 494 return (ret); 495 } 496 497 static void 498 send_status(SocketEntry *e, int success) 499 { 500 int r; 501 502 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 503 (r = sshbuf_put_u8(e->output, success ? 504 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 505 fatal_fr(r, "compose"); 506 } 507 508 /* send list of supported public keys to 'client' */ 509 static void 510 process_request_identities(SocketEntry *e) 511 { 512 Identity *id; 513 struct sshbuf *msg, *keys; 514 int r; 515 u_int nentries = 0; 516 517 debug2_f("entering"); 518 519 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 520 fatal_f("sshbuf_new failed"); 521 TAILQ_FOREACH(id, &idtab->idlist, next) { 522 /* identity not visible, don't include in response */ 523 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 524 continue; 525 if ((r = sshkey_puts_opts(id->key, keys, 526 SSHKEY_SERIALIZE_INFO)) != 0 || 527 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 528 error_fr(r, "compose key/comment"); 529 continue; 530 } 531 nentries++; 532 } 533 debug2_f("replying with %u allowed of %u available keys", 534 nentries, idtab->nentries); 535 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 536 (r = sshbuf_put_u32(msg, nentries)) != 0 || 537 (r = sshbuf_putb(msg, keys)) != 0) 538 fatal_fr(r, "compose"); 539 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 540 fatal_fr(r, "enqueue"); 541 sshbuf_free(msg); 542 sshbuf_free(keys); 543 } 544 545 546 static const char * 547 agent_decode_alg(struct sshkey *key, u_int flags) 548 { 549 if (key->type == KEY_RSA) { 550 if (flags & SSH_AGENT_RSA_SHA2_256) 551 return "rsa-sha2-256"; 552 else if (flags & SSH_AGENT_RSA_SHA2_512) 553 return "rsa-sha2-512"; 554 } else if (key->type == KEY_RSA_CERT) { 555 if (flags & SSH_AGENT_RSA_SHA2_256) 556 return "rsa-sha2-256-cert-v01@openssh.com"; 557 else if (flags & SSH_AGENT_RSA_SHA2_512) 558 return "rsa-sha2-512-cert-v01@openssh.com"; 559 } 560 return NULL; 561 } 562 563 /* 564 * Attempt to parse the contents of a buffer as a SSH publickey userauth 565 * request, checking its contents for consistency and matching the embedded 566 * key against the one that is being used for signing. 567 * Note: does not modify msg buffer. 568 * Optionally extract the username, session ID and/or hostkey from the request. 569 */ 570 static int 571 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 572 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 573 { 574 struct sshbuf *b = NULL, *sess_id = NULL; 575 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 576 int r; 577 u_char t, sig_follows; 578 struct sshkey *mkey = NULL, *hostkey = NULL; 579 580 if (userp != NULL) 581 *userp = NULL; 582 if (sess_idp != NULL) 583 *sess_idp = NULL; 584 if (hostkeyp != NULL) 585 *hostkeyp = NULL; 586 if ((b = sshbuf_fromb(msg)) == NULL) 587 fatal_f("sshbuf_fromb"); 588 589 /* SSH userauth request */ 590 if ((r = sshbuf_froms(b, &sess_id)) != 0) 591 goto out; 592 if (sshbuf_len(sess_id) == 0) { 593 r = SSH_ERR_INVALID_FORMAT; 594 goto out; 595 } 596 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 597 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 598 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 599 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 600 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 601 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 602 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 603 goto out; 604 if (t != SSH2_MSG_USERAUTH_REQUEST || 605 sig_follows != 1 || 606 strcmp(service, "ssh-connection") != 0 || 607 !sshkey_equal(expected_key, mkey) || 608 sshkey_type_from_name(pkalg) != expected_key->type) { 609 r = SSH_ERR_INVALID_FORMAT; 610 goto out; 611 } 612 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 613 if ((r = sshkey_froms(b, &hostkey)) != 0) 614 goto out; 615 } else if (strcmp(method, "publickey") != 0) { 616 r = SSH_ERR_INVALID_FORMAT; 617 goto out; 618 } 619 if (sshbuf_len(b) != 0) { 620 r = SSH_ERR_INVALID_FORMAT; 621 goto out; 622 } 623 /* success */ 624 r = 0; 625 debug3_f("well formed userauth"); 626 if (userp != NULL) { 627 *userp = user; 628 user = NULL; 629 } 630 if (sess_idp != NULL) { 631 *sess_idp = sess_id; 632 sess_id = NULL; 633 } 634 if (hostkeyp != NULL) { 635 *hostkeyp = hostkey; 636 hostkey = NULL; 637 } 638 out: 639 sshbuf_free(b); 640 sshbuf_free(sess_id); 641 free(user); 642 free(service); 643 free(method); 644 free(pkalg); 645 sshkey_free(mkey); 646 sshkey_free(hostkey); 647 return r; 648 } 649 650 /* 651 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 652 * Note: does not modify buffer. 653 */ 654 static int 655 parse_sshsig_request(struct sshbuf *msg) 656 { 657 int r; 658 struct sshbuf *b; 659 660 if ((b = sshbuf_fromb(msg)) == NULL) 661 fatal_f("sshbuf_fromb"); 662 663 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 664 (r = sshbuf_consume(b, 6)) != 0 || 665 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 666 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 667 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 668 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 669 goto out; 670 if (sshbuf_len(b) != 0) { 671 r = SSH_ERR_INVALID_FORMAT; 672 goto out; 673 } 674 /* success */ 675 r = 0; 676 out: 677 sshbuf_free(b); 678 return r; 679 } 680 681 /* 682 * This function inspects a message to be signed by a FIDO key that has a 683 * web-like application string (i.e. one that does not begin with "ssh:". 684 * It checks that the message is one of those expected for SSH operations 685 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 686 * for the web. 687 */ 688 static int 689 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 690 { 691 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 692 debug_f("signed data matches public key userauth request"); 693 return 1; 694 } 695 if (parse_sshsig_request(data) == 0) { 696 debug_f("signed data matches SSHSIG signature request"); 697 return 1; 698 } 699 700 /* XXX check CA signature operation */ 701 702 error("web-origin key attempting to sign non-SSH message"); 703 return 0; 704 } 705 706 static int 707 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 708 { 709 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 710 return SSH_ERR_INVALID_ARGUMENT; 711 if (sshbuf_len(a) != sshbuf_len(b)) 712 return SSH_ERR_INVALID_FORMAT; 713 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 714 return SSH_ERR_INVALID_FORMAT; 715 return 0; 716 } 717 718 /* ssh2 only */ 719 static void 720 process_sign_request2(SocketEntry *e) 721 { 722 u_char *signature = NULL; 723 size_t slen = 0; 724 u_int compat = 0, flags; 725 int r, ok = -1, retried = 0; 726 char *fp = NULL, *pin = NULL, *prompt = NULL; 727 char *user = NULL, *sig_dest = NULL; 728 const char *fwd_host = NULL, *dest_host = NULL; 729 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 730 struct sshkey *key = NULL, *hostkey = NULL; 731 struct identity *id; 732 struct notifier_ctx *notifier = NULL; 733 734 debug_f("entering"); 735 736 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 737 fatal_f("sshbuf_new failed"); 738 if ((r = sshkey_froms(e->request, &key)) != 0 || 739 (r = sshbuf_get_stringb(e->request, data)) != 0 || 740 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 741 error_fr(r, "parse"); 742 goto send; 743 } 744 745 if ((id = lookup_identity(key)) == NULL) { 746 verbose_f("%s key not found", sshkey_type(key)); 747 goto send; 748 } 749 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 750 SSH_FP_DEFAULT)) == NULL) 751 fatal_f("fingerprint failed"); 752 753 if (id->ndest_constraints != 0) { 754 if (e->nsession_ids == 0) { 755 logit_f("refusing use of destination-constrained key " 756 "to sign on unbound connection"); 757 goto send; 758 } 759 if (parse_userauth_request(data, key, &user, &sid, 760 &hostkey) != 0) { 761 logit_f("refusing use of destination-constrained key " 762 "to sign an unidentified signature"); 763 goto send; 764 } 765 /* XXX logspam */ 766 debug_f("user=%s", user); 767 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 768 goto send; 769 /* XXX display fwd_host/dest_host in askpass UI */ 770 /* 771 * Ensure that the session ID is the most recent one 772 * registered on the socket - it should have been bound by 773 * ssh immediately before userauth. 774 */ 775 if (buf_equal(sid, 776 e->session_ids[e->nsession_ids - 1].sid) != 0) { 777 error_f("unexpected session ID (%zu listed) on " 778 "signature request for target user %s with " 779 "key %s %s", e->nsession_ids, user, 780 sshkey_type(id->key), fp); 781 goto send; 782 } 783 /* 784 * Ensure that the hostkey embedded in the signature matches 785 * the one most recently bound to the socket. An exception is 786 * made for the initial forwarding hop. 787 */ 788 if (e->nsession_ids > 1 && hostkey == NULL) { 789 error_f("refusing use of destination-constrained key: " 790 "no hostkey recorded in signature for forwarded " 791 "connection"); 792 goto send; 793 } 794 if (hostkey != NULL && !sshkey_equal(hostkey, 795 e->session_ids[e->nsession_ids - 1].key)) { 796 error_f("refusing use of destination-constrained key: " 797 "mismatch between hostkey in request and most " 798 "recently bound session"); 799 goto send; 800 } 801 xasprintf(&sig_dest, "public key authentication request for " 802 "user \"%s\" to listed host", user); 803 } 804 if (id->confirm && confirm_key(id, sig_dest) != 0) { 805 verbose_f("user refused key"); 806 goto send; 807 } 808 if (sshkey_is_sk(id->key)) { 809 if (restrict_websafe && 810 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 811 !check_websafe_message_contents(key, data)) { 812 /* error already logged */ 813 goto send; 814 } 815 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 816 notifier = notify_start(0, 817 "Confirm user presence for key %s %s%s%s", 818 sshkey_type(id->key), fp, 819 sig_dest == NULL ? "" : "\n", 820 sig_dest == NULL ? "" : sig_dest); 821 } 822 } 823 retry_pin: 824 if ((r = sshkey_sign(id->key, &signature, &slen, 825 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 826 id->sk_provider, pin, compat)) != 0) { 827 debug_fr(r, "sshkey_sign"); 828 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 829 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 830 notify_complete(notifier, NULL); 831 notifier = NULL; 832 /* XXX include sig_dest */ 833 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 834 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 835 " and confirm user presence " : " ", 836 sshkey_type(id->key), fp); 837 pin = read_passphrase(prompt, RP_USE_ASKPASS); 838 retried = 1; 839 goto retry_pin; 840 } 841 error_fr(r, "sshkey_sign"); 842 goto send; 843 } 844 /* Success */ 845 ok = 0; 846 debug_f("good signature"); 847 send: 848 notify_complete(notifier, "User presence confirmed"); 849 850 if (ok == 0) { 851 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 852 (r = sshbuf_put_string(msg, signature, slen)) != 0) 853 fatal_fr(r, "compose"); 854 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 855 fatal_fr(r, "compose failure"); 856 857 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 858 fatal_fr(r, "enqueue"); 859 860 sshbuf_free(sid); 861 sshbuf_free(data); 862 sshbuf_free(msg); 863 sshkey_free(key); 864 sshkey_free(hostkey); 865 free(fp); 866 free(signature); 867 free(sig_dest); 868 free(user); 869 free(prompt); 870 if (pin != NULL) 871 freezero(pin, strlen(pin)); 872 } 873 874 /* shared */ 875 static void 876 process_remove_identity(SocketEntry *e) 877 { 878 int r, success = 0; 879 struct sshkey *key = NULL; 880 Identity *id; 881 882 debug2_f("entering"); 883 if ((r = sshkey_froms(e->request, &key)) != 0) { 884 error_fr(r, "parse key"); 885 goto done; 886 } 887 if ((id = lookup_identity(key)) == NULL) { 888 debug_f("key not found"); 889 goto done; 890 } 891 /* identity not visible, cannot be removed */ 892 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 893 goto done; /* error already logged */ 894 /* We have this key, free it. */ 895 if (idtab->nentries < 1) 896 fatal_f("internal error: nentries %d", idtab->nentries); 897 TAILQ_REMOVE(&idtab->idlist, id, next); 898 free_identity(id); 899 idtab->nentries--; 900 success = 1; 901 done: 902 sshkey_free(key); 903 send_status(e, success); 904 } 905 906 static void 907 process_remove_all_identities(SocketEntry *e) 908 { 909 Identity *id; 910 911 debug2_f("entering"); 912 /* Loop over all identities and clear the keys. */ 913 for (id = TAILQ_FIRST(&idtab->idlist); id; 914 id = TAILQ_FIRST(&idtab->idlist)) { 915 TAILQ_REMOVE(&idtab->idlist, id, next); 916 free_identity(id); 917 } 918 919 /* Mark that there are no identities. */ 920 idtab->nentries = 0; 921 922 /* Send success. */ 923 send_status(e, 1); 924 } 925 926 /* removes expired keys and returns number of seconds until the next expiry */ 927 static time_t 928 reaper(void) 929 { 930 time_t deadline = 0, now = monotime(); 931 Identity *id, *nxt; 932 933 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 934 nxt = TAILQ_NEXT(id, next); 935 if (id->death == 0) 936 continue; 937 if (now >= id->death) { 938 debug("expiring key '%s'", id->comment); 939 TAILQ_REMOVE(&idtab->idlist, id, next); 940 free_identity(id); 941 idtab->nentries--; 942 } else 943 deadline = (deadline == 0) ? id->death : 944 MINIMUM(deadline, id->death); 945 } 946 if (deadline == 0 || deadline <= now) 947 return 0; 948 else 949 return (deadline - now); 950 } 951 952 static int 953 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 954 { 955 u_char key_is_ca; 956 size_t elen = 0; 957 int r; 958 struct sshkey *k = NULL; 959 char *fp; 960 961 memset(dch, '\0', sizeof(*dch)); 962 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 963 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 964 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 965 error_fr(r, "parse"); 966 goto out; 967 } 968 if (elen != 0) { 969 error_f("unsupported extensions (len %zu)", elen); 970 r = SSH_ERR_FEATURE_UNSUPPORTED; 971 goto out; 972 } 973 if (*dch->hostname == '\0') { 974 free(dch->hostname); 975 dch->hostname = NULL; 976 } 977 if (*dch->user == '\0') { 978 free(dch->user); 979 dch->user = NULL; 980 } 981 while (sshbuf_len(b) != 0) { 982 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 983 dch->nkeys + 1, sizeof(*dch->keys)); 984 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 985 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 986 if ((r = sshkey_froms(b, &k)) != 0 || 987 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 988 goto out; 989 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 990 SSH_FP_DEFAULT)) == NULL) 991 fatal_f("fingerprint failed"); 992 debug3_f("%s%s%s: adding %skey %s %s", 993 dch->user == NULL ? "" : dch->user, 994 dch->user == NULL ? "" : "@", 995 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 996 free(fp); 997 dch->keys[dch->nkeys] = k; 998 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 999 dch->nkeys++; 1000 k = NULL; /* transferred */ 1001 } 1002 /* success */ 1003 r = 0; 1004 out: 1005 sshkey_free(k); 1006 return r; 1007 } 1008 1009 static int 1010 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1011 { 1012 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1013 int r; 1014 size_t elen = 0; 1015 1016 debug3_f("entering"); 1017 1018 memset(dc, '\0', sizeof(*dc)); 1019 if ((r = sshbuf_froms(m, &b)) != 0 || 1020 (r = sshbuf_froms(b, &frombuf)) != 0 || 1021 (r = sshbuf_froms(b, &tobuf)) != 0 || 1022 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1023 error_fr(r, "parse"); 1024 goto out; 1025 } 1026 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1027 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1028 goto out; /* already logged */ 1029 if (elen != 0) { 1030 error_f("unsupported extensions (len %zu)", elen); 1031 r = SSH_ERR_FEATURE_UNSUPPORTED; 1032 goto out; 1033 } 1034 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1035 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1036 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1037 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1038 /* check consistency */ 1039 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1040 dc->from.user != NULL) { 1041 error_f("inconsistent \"from\" specification"); 1042 r = SSH_ERR_INVALID_FORMAT; 1043 goto out; 1044 } 1045 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1046 error_f("incomplete \"to\" specification"); 1047 r = SSH_ERR_INVALID_FORMAT; 1048 goto out; 1049 } 1050 /* success */ 1051 r = 0; 1052 out: 1053 sshbuf_free(b); 1054 sshbuf_free(frombuf); 1055 sshbuf_free(tobuf); 1056 return r; 1057 } 1058 1059 static int 1060 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1061 struct dest_constraint **dcsp, size_t *ndcsp) 1062 { 1063 char *ext_name = NULL; 1064 int r; 1065 struct sshbuf *b = NULL; 1066 1067 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1068 error_fr(r, "parse constraint extension"); 1069 goto out; 1070 } 1071 debug_f("constraint ext %s", ext_name); 1072 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1073 if (sk_providerp == NULL) { 1074 error_f("%s not valid here", ext_name); 1075 r = SSH_ERR_INVALID_FORMAT; 1076 goto out; 1077 } 1078 if (*sk_providerp != NULL) { 1079 error_f("%s already set", ext_name); 1080 r = SSH_ERR_INVALID_FORMAT; 1081 goto out; 1082 } 1083 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1084 error_fr(r, "parse %s", ext_name); 1085 goto out; 1086 } 1087 } else if (strcmp(ext_name, 1088 "restrict-destination-v00@openssh.com") == 0) { 1089 if (*dcsp != NULL) { 1090 error_f("%s already set", ext_name); 1091 goto out; 1092 } 1093 if ((r = sshbuf_froms(m, &b)) != 0) { 1094 error_fr(r, "parse %s outer", ext_name); 1095 goto out; 1096 } 1097 while (sshbuf_len(b) != 0) { 1098 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1099 error_f("too many %s constraints", ext_name); 1100 goto out; 1101 } 1102 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1103 sizeof(**dcsp)); 1104 if ((r = parse_dest_constraint(b, 1105 *dcsp + (*ndcsp)++)) != 0) 1106 goto out; /* error already logged */ 1107 } 1108 } else { 1109 error_f("unsupported constraint \"%s\"", ext_name); 1110 r = SSH_ERR_FEATURE_UNSUPPORTED; 1111 goto out; 1112 } 1113 /* success */ 1114 r = 0; 1115 out: 1116 free(ext_name); 1117 sshbuf_free(b); 1118 return r; 1119 } 1120 1121 static int 1122 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1123 u_int *secondsp, int *confirmp, char **sk_providerp, 1124 struct dest_constraint **dcsp, size_t *ndcsp) 1125 { 1126 u_char ctype; 1127 int r; 1128 u_int seconds, maxsign = 0; 1129 1130 while (sshbuf_len(m)) { 1131 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1132 error_fr(r, "parse constraint type"); 1133 goto out; 1134 } 1135 switch (ctype) { 1136 case SSH_AGENT_CONSTRAIN_LIFETIME: 1137 if (*deathp != 0) { 1138 error_f("lifetime already set"); 1139 r = SSH_ERR_INVALID_FORMAT; 1140 goto out; 1141 } 1142 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1143 error_fr(r, "parse lifetime constraint"); 1144 goto out; 1145 } 1146 *deathp = monotime() + seconds; 1147 *secondsp = seconds; 1148 break; 1149 case SSH_AGENT_CONSTRAIN_CONFIRM: 1150 if (*confirmp != 0) { 1151 error_f("confirm already set"); 1152 r = SSH_ERR_INVALID_FORMAT; 1153 goto out; 1154 } 1155 *confirmp = 1; 1156 break; 1157 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1158 if (k == NULL) { 1159 error_f("maxsign not valid here"); 1160 r = SSH_ERR_INVALID_FORMAT; 1161 goto out; 1162 } 1163 if (maxsign != 0) { 1164 error_f("maxsign already set"); 1165 r = SSH_ERR_INVALID_FORMAT; 1166 goto out; 1167 } 1168 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1169 error_fr(r, "parse maxsign constraint"); 1170 goto out; 1171 } 1172 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1173 error_fr(r, "enable maxsign"); 1174 goto out; 1175 } 1176 break; 1177 case SSH_AGENT_CONSTRAIN_EXTENSION: 1178 if ((r = parse_key_constraint_extension(m, 1179 sk_providerp, dcsp, ndcsp)) != 0) 1180 goto out; /* error already logged */ 1181 break; 1182 default: 1183 error_f("Unknown constraint %d", ctype); 1184 r = SSH_ERR_FEATURE_UNSUPPORTED; 1185 goto out; 1186 } 1187 } 1188 /* success */ 1189 r = 0; 1190 out: 1191 return r; 1192 } 1193 1194 static void 1195 process_add_identity(SocketEntry *e) 1196 { 1197 Identity *id; 1198 int success = 0, confirm = 0; 1199 char *fp, *comment = NULL, *sk_provider = NULL; 1200 char canonical_provider[PATH_MAX]; 1201 time_t death = 0; 1202 u_int seconds = 0; 1203 struct dest_constraint *dest_constraints = NULL; 1204 size_t ndest_constraints = 0; 1205 struct sshkey *k = NULL; 1206 int r = SSH_ERR_INTERNAL_ERROR; 1207 1208 debug2_f("entering"); 1209 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1210 k == NULL || 1211 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1212 error_fr(r, "parse"); 1213 goto out; 1214 } 1215 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1216 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1217 error_f("failed to parse constraints"); 1218 sshbuf_reset(e->request); 1219 goto out; 1220 } 1221 1222 if (sk_provider != NULL) { 1223 if (!sshkey_is_sk(k)) { 1224 error("Cannot add provider: %s is not an " 1225 "authenticator-hosted key", sshkey_type(k)); 1226 goto out; 1227 } 1228 if (strcasecmp(sk_provider, "internal") == 0) { 1229 debug_f("internal provider"); 1230 } else { 1231 if (e->nsession_ids != 0 && !remote_add_provider) { 1232 verbose("failed add of SK provider \"%.100s\": " 1233 "remote addition of providers is disabled", 1234 sk_provider); 1235 goto out; 1236 } 1237 if (realpath(sk_provider, canonical_provider) == NULL) { 1238 verbose("failed provider \"%.100s\": " 1239 "realpath: %s", sk_provider, 1240 strerror(errno)); 1241 goto out; 1242 } 1243 free(sk_provider); 1244 sk_provider = xstrdup(canonical_provider); 1245 if (match_pattern_list(sk_provider, 1246 allowed_providers, 0) != 1) { 1247 error("Refusing add key: " 1248 "provider %s not allowed", sk_provider); 1249 goto out; 1250 } 1251 } 1252 } 1253 if ((r = sshkey_shield_private(k)) != 0) { 1254 error_fr(r, "shield private"); 1255 goto out; 1256 } 1257 if (lifetime && !death) 1258 death = monotime() + lifetime; 1259 if ((id = lookup_identity(k)) == NULL) { 1260 id = xcalloc(1, sizeof(Identity)); 1261 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1262 /* Increment the number of identities. */ 1263 idtab->nentries++; 1264 } else { 1265 /* identity not visible, do not update */ 1266 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1267 goto out; /* error already logged */ 1268 /* key state might have been updated */ 1269 sshkey_free(id->key); 1270 free(id->comment); 1271 free(id->sk_provider); 1272 free_dest_constraints(id->dest_constraints, 1273 id->ndest_constraints); 1274 } 1275 /* success */ 1276 id->key = k; 1277 id->comment = comment; 1278 id->death = death; 1279 id->confirm = confirm; 1280 id->sk_provider = sk_provider; 1281 id->dest_constraints = dest_constraints; 1282 id->ndest_constraints = ndest_constraints; 1283 1284 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1285 SSH_FP_DEFAULT)) == NULL) 1286 fatal_f("sshkey_fingerprint failed"); 1287 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1288 "(provider: %s) (destination constraints: %zu)", 1289 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1290 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1291 free(fp); 1292 /* transferred */ 1293 k = NULL; 1294 comment = NULL; 1295 sk_provider = NULL; 1296 dest_constraints = NULL; 1297 ndest_constraints = 0; 1298 success = 1; 1299 out: 1300 free(sk_provider); 1301 free(comment); 1302 sshkey_free(k); 1303 free_dest_constraints(dest_constraints, ndest_constraints); 1304 send_status(e, success); 1305 } 1306 1307 /* XXX todo: encrypt sensitive data with passphrase */ 1308 static void 1309 process_lock_agent(SocketEntry *e, int lock) 1310 { 1311 int r, success = 0, delay; 1312 char *passwd; 1313 u_char passwdhash[LOCK_SIZE]; 1314 static u_int fail_count = 0; 1315 size_t pwlen; 1316 1317 debug2_f("entering"); 1318 /* 1319 * This is deliberately fatal: the user has requested that we lock, 1320 * but we can't parse their request properly. The only safe thing to 1321 * do is abort. 1322 */ 1323 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1324 fatal_fr(r, "parse"); 1325 if (pwlen == 0) { 1326 debug("empty password not supported"); 1327 } else if (locked && !lock) { 1328 if (bcrypt_pbkdf(passwd, pwlen, (uint8_t *)lock_salt, sizeof(lock_salt), 1329 (uint8_t *)passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1330 fatal("bcrypt_pbkdf"); 1331 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1332 debug("agent unlocked"); 1333 locked = 0; 1334 fail_count = 0; 1335 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1336 success = 1; 1337 } else { 1338 /* delay in 0.1s increments up to 10s */ 1339 if (fail_count < 100) 1340 fail_count++; 1341 delay = 100000 * fail_count; 1342 debug("unlock failed, delaying %0.1lf seconds", 1343 (double)delay/1000000); 1344 usleep(delay); 1345 } 1346 explicit_bzero(passwdhash, sizeof(passwdhash)); 1347 } else if (!locked && lock) { 1348 debug("agent locked"); 1349 locked = 1; 1350 arc4random_buf(lock_salt, sizeof(lock_salt)); 1351 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1352 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1353 fatal("bcrypt_pbkdf"); 1354 success = 1; 1355 } 1356 freezero(passwd, pwlen); 1357 send_status(e, success); 1358 } 1359 1360 static void 1361 no_identities(SocketEntry *e) 1362 { 1363 struct sshbuf *msg; 1364 int r; 1365 1366 if ((msg = sshbuf_new()) == NULL) 1367 fatal_f("sshbuf_new failed"); 1368 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1369 (r = sshbuf_put_u32(msg, 0)) != 0 || 1370 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1371 fatal_fr(r, "compose"); 1372 sshbuf_free(msg); 1373 } 1374 1375 #ifdef ENABLE_PKCS11 1376 static void 1377 process_add_smartcard_key(SocketEntry *e) 1378 { 1379 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1380 char **comments = NULL; 1381 int r, i, count = 0, success = 0, confirm = 0; 1382 u_int seconds = 0; 1383 time_t death = 0; 1384 struct sshkey **keys = NULL, *k; 1385 Identity *id; 1386 struct dest_constraint *dest_constraints = NULL; 1387 size_t ndest_constraints = 0; 1388 1389 debug2_f("entering"); 1390 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1391 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1392 error_fr(r, "parse"); 1393 goto send; 1394 } 1395 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1396 NULL, &dest_constraints, &ndest_constraints) != 0) { 1397 error_f("failed to parse constraints"); 1398 goto send; 1399 } 1400 if (e->nsession_ids != 0 && !remote_add_provider) { 1401 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1402 "providers is disabled", provider); 1403 goto send; 1404 } 1405 if (realpath(provider, canonical_provider) == NULL) { 1406 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1407 provider, strerror(errno)); 1408 goto send; 1409 } 1410 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1411 verbose("refusing PKCS#11 add of \"%.100s\": " 1412 "provider not allowed", canonical_provider); 1413 goto send; 1414 } 1415 debug_f("add %.100s", canonical_provider); 1416 if (lifetime && !death) 1417 death = monotime() + lifetime; 1418 1419 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1420 for (i = 0; i < count; i++) { 1421 k = keys[i]; 1422 if (lookup_identity(k) == NULL) { 1423 id = xcalloc(1, sizeof(Identity)); 1424 id->key = k; 1425 keys[i] = NULL; /* transferred */ 1426 id->provider = xstrdup(canonical_provider); 1427 if (*comments[i] != '\0') { 1428 id->comment = comments[i]; 1429 comments[i] = NULL; /* transferred */ 1430 } else { 1431 id->comment = xstrdup(canonical_provider); 1432 } 1433 id->death = death; 1434 id->confirm = confirm; 1435 id->dest_constraints = dest_constraints; 1436 id->ndest_constraints = ndest_constraints; 1437 dest_constraints = NULL; /* transferred */ 1438 ndest_constraints = 0; 1439 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1440 idtab->nentries++; 1441 success = 1; 1442 } 1443 /* XXX update constraints for existing keys */ 1444 sshkey_free(keys[i]); 1445 free(comments[i]); 1446 } 1447 send: 1448 free(pin); 1449 free(provider); 1450 free(keys); 1451 free(comments); 1452 free_dest_constraints(dest_constraints, ndest_constraints); 1453 send_status(e, success); 1454 } 1455 1456 static void 1457 process_remove_smartcard_key(SocketEntry *e) 1458 { 1459 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1460 int r, success = 0; 1461 Identity *id, *nxt; 1462 1463 debug2_f("entering"); 1464 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1465 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1466 error_fr(r, "parse"); 1467 goto send; 1468 } 1469 free(pin); 1470 1471 if (realpath(provider, canonical_provider) == NULL) { 1472 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1473 provider, strerror(errno)); 1474 goto send; 1475 } 1476 1477 debug_f("remove %.100s", canonical_provider); 1478 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1479 nxt = TAILQ_NEXT(id, next); 1480 /* Skip file--based keys */ 1481 if (id->provider == NULL) 1482 continue; 1483 if (!strcmp(canonical_provider, id->provider)) { 1484 TAILQ_REMOVE(&idtab->idlist, id, next); 1485 free_identity(id); 1486 idtab->nentries--; 1487 } 1488 } 1489 if (pkcs11_del_provider(canonical_provider) == 0) 1490 success = 1; 1491 else 1492 error_f("pkcs11_del_provider failed"); 1493 send: 1494 free(provider); 1495 send_status(e, success); 1496 } 1497 #endif /* ENABLE_PKCS11 */ 1498 1499 static int 1500 process_ext_session_bind(SocketEntry *e) 1501 { 1502 int r, sid_match, key_match; 1503 struct sshkey *key = NULL; 1504 struct sshbuf *sid = NULL, *sig = NULL; 1505 char *fp = NULL; 1506 size_t i; 1507 u_char fwd = 0; 1508 1509 debug2_f("entering"); 1510 if ((r = sshkey_froms(e->request, &key)) != 0 || 1511 (r = sshbuf_froms(e->request, &sid)) != 0 || 1512 (r = sshbuf_froms(e->request, &sig)) != 0 || 1513 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1514 error_fr(r, "parse"); 1515 goto out; 1516 } 1517 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1518 SSH_FP_DEFAULT)) == NULL) 1519 fatal_f("fingerprint failed"); 1520 /* check signature with hostkey on session ID */ 1521 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1522 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1523 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1524 goto out; 1525 } 1526 /* check whether sid/key already recorded */ 1527 for (i = 0; i < e->nsession_ids; i++) { 1528 if (!e->session_ids[i].forwarded) { 1529 error_f("attempt to bind session ID to socket " 1530 "previously bound for authentication attempt"); 1531 r = -1; 1532 goto out; 1533 } 1534 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1535 key_match = sshkey_equal(key, e->session_ids[i].key); 1536 if (sid_match && key_match) { 1537 debug_f("session ID already recorded for %s %s", 1538 sshkey_type(key), fp); 1539 r = 0; 1540 goto out; 1541 } else if (sid_match) { 1542 error_f("session ID recorded against different key " 1543 "for %s %s", sshkey_type(key), fp); 1544 r = -1; 1545 goto out; 1546 } 1547 /* 1548 * new sid with previously-seen key can happen, e.g. multiple 1549 * connections to the same host. 1550 */ 1551 } 1552 /* record new key/sid */ 1553 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1554 error_f("too many session IDs recorded"); 1555 goto out; 1556 } 1557 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1558 e->nsession_ids + 1, sizeof(*e->session_ids)); 1559 i = e->nsession_ids++; 1560 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1561 AGENT_MAX_SESSION_IDS); 1562 e->session_ids[i].key = key; 1563 e->session_ids[i].forwarded = fwd != 0; 1564 key = NULL; /* transferred */ 1565 /* can't transfer sid; it's refcounted and scoped to request's life */ 1566 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1567 fatal_f("sshbuf_new"); 1568 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1569 fatal_fr(r, "sshbuf_putb session ID"); 1570 /* success */ 1571 r = 0; 1572 out: 1573 free(fp); 1574 sshkey_free(key); 1575 sshbuf_free(sid); 1576 sshbuf_free(sig); 1577 return r == 0 ? 1 : 0; 1578 } 1579 1580 static void 1581 process_extension(SocketEntry *e) 1582 { 1583 int r, success = 0; 1584 char *name; 1585 1586 debug2_f("entering"); 1587 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1588 error_fr(r, "parse"); 1589 goto send; 1590 } 1591 if (strcmp(name, "session-bind@openssh.com") == 0) 1592 success = process_ext_session_bind(e); 1593 else 1594 debug_f("unsupported extension \"%s\"", name); 1595 free(name); 1596 send: 1597 send_status(e, success); 1598 } 1599 /* 1600 * dispatch incoming message. 1601 * returns 1 on success, 0 for incomplete messages or -1 on error. 1602 */ 1603 static int 1604 process_message(u_int socknum) 1605 { 1606 u_int msg_len; 1607 u_char type; 1608 const u_char *cp; 1609 int r; 1610 SocketEntry *e; 1611 1612 if (socknum >= sockets_alloc) 1613 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1614 e = &sockets[socknum]; 1615 1616 if (sshbuf_len(e->input) < 5) 1617 return 0; /* Incomplete message header. */ 1618 cp = sshbuf_ptr(e->input); 1619 msg_len = PEEK_U32(cp); 1620 if (msg_len > AGENT_MAX_LEN) { 1621 debug_f("socket %u (fd=%d) message too long %u > %u", 1622 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1623 return -1; 1624 } 1625 if (sshbuf_len(e->input) < msg_len + 4) 1626 return 0; /* Incomplete message body. */ 1627 1628 /* move the current input to e->request */ 1629 sshbuf_reset(e->request); 1630 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1631 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1632 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1633 r == SSH_ERR_STRING_TOO_LARGE) { 1634 error_fr(r, "parse"); 1635 return -1; 1636 } 1637 fatal_fr(r, "parse"); 1638 } 1639 1640 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1641 1642 /* check whether agent is locked */ 1643 if (locked && type != SSH_AGENTC_UNLOCK) { 1644 sshbuf_reset(e->request); 1645 switch (type) { 1646 case SSH2_AGENTC_REQUEST_IDENTITIES: 1647 /* send empty lists */ 1648 no_identities(e); 1649 break; 1650 default: 1651 /* send a fail message for all other request types */ 1652 send_status(e, 0); 1653 } 1654 return 1; 1655 } 1656 1657 switch (type) { 1658 case SSH_AGENTC_LOCK: 1659 case SSH_AGENTC_UNLOCK: 1660 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1661 break; 1662 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1663 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1664 break; 1665 /* ssh2 */ 1666 case SSH2_AGENTC_SIGN_REQUEST: 1667 process_sign_request2(e); 1668 break; 1669 case SSH2_AGENTC_REQUEST_IDENTITIES: 1670 process_request_identities(e); 1671 break; 1672 case SSH2_AGENTC_ADD_IDENTITY: 1673 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1674 process_add_identity(e); 1675 break; 1676 case SSH2_AGENTC_REMOVE_IDENTITY: 1677 process_remove_identity(e); 1678 break; 1679 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1680 process_remove_all_identities(e); 1681 break; 1682 #ifdef ENABLE_PKCS11 1683 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1684 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1685 process_add_smartcard_key(e); 1686 break; 1687 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1688 process_remove_smartcard_key(e); 1689 break; 1690 #endif /* ENABLE_PKCS11 */ 1691 case SSH_AGENTC_EXTENSION: 1692 process_extension(e); 1693 break; 1694 default: 1695 /* Unknown message. Respond with failure. */ 1696 error("Unknown message %d", type); 1697 sshbuf_reset(e->request); 1698 send_status(e, 0); 1699 break; 1700 } 1701 return 1; 1702 } 1703 1704 static void 1705 new_socket(sock_type type, int fd) 1706 { 1707 u_int i, old_alloc, new_alloc; 1708 1709 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1710 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1711 set_nonblock(fd); 1712 1713 if (fd > max_fd) 1714 max_fd = fd; 1715 1716 for (i = 0; i < sockets_alloc; i++) 1717 if (sockets[i].type == AUTH_UNUSED) { 1718 sockets[i].fd = fd; 1719 if ((sockets[i].input = sshbuf_new()) == NULL || 1720 (sockets[i].output = sshbuf_new()) == NULL || 1721 (sockets[i].request = sshbuf_new()) == NULL) 1722 fatal_f("sshbuf_new failed"); 1723 sockets[i].type = type; 1724 return; 1725 } 1726 old_alloc = sockets_alloc; 1727 new_alloc = sockets_alloc + 10; 1728 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1729 sizeof(sockets[0])); 1730 for (i = old_alloc; i < new_alloc; i++) 1731 sockets[i].type = AUTH_UNUSED; 1732 sockets_alloc = new_alloc; 1733 sockets[old_alloc].fd = fd; 1734 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1735 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1736 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1737 fatal_f("sshbuf_new failed"); 1738 sockets[old_alloc].type = type; 1739 } 1740 1741 static int 1742 handle_socket_read(u_int socknum) 1743 { 1744 struct sockaddr_un sunaddr; 1745 socklen_t slen; 1746 uid_t euid; 1747 gid_t egid; 1748 int fd; 1749 1750 slen = sizeof(sunaddr); 1751 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1752 if (fd == -1) { 1753 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1754 return -1; 1755 } 1756 if (getpeereid(fd, &euid, &egid) == -1) { 1757 error("getpeereid %d failed: %s", fd, strerror(errno)); 1758 close(fd); 1759 return -1; 1760 } 1761 if ((euid != 0) && (getuid() != euid)) { 1762 error("uid mismatch: peer euid %u != uid %u", 1763 (u_int) euid, (u_int) getuid()); 1764 close(fd); 1765 return -1; 1766 } 1767 new_socket(AUTH_CONNECTION, fd); 1768 return 0; 1769 } 1770 1771 static int 1772 handle_conn_read(u_int socknum) 1773 { 1774 char buf[AGENT_RBUF_LEN]; 1775 ssize_t len; 1776 int r; 1777 1778 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1779 if (len == -1) { 1780 if (errno == EAGAIN || errno == EINTR) 1781 return 0; 1782 error_f("read error on socket %u (fd %d): %s", 1783 socknum, sockets[socknum].fd, strerror(errno)); 1784 } 1785 return -1; 1786 } 1787 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1788 fatal_fr(r, "compose"); 1789 explicit_bzero(buf, sizeof(buf)); 1790 for (;;) { 1791 if ((r = process_message(socknum)) == -1) 1792 return -1; 1793 else if (r == 0) 1794 break; 1795 } 1796 return 0; 1797 } 1798 1799 static int 1800 handle_conn_write(u_int socknum) 1801 { 1802 ssize_t len; 1803 int r; 1804 1805 if (sshbuf_len(sockets[socknum].output) == 0) 1806 return 0; /* shouldn't happen */ 1807 if ((len = write(sockets[socknum].fd, 1808 sshbuf_ptr(sockets[socknum].output), 1809 sshbuf_len(sockets[socknum].output))) <= 0) { 1810 if (len == -1) { 1811 if (errno == EAGAIN || errno == EINTR) 1812 return 0; 1813 error_f("read error on socket %u (fd %d): %s", 1814 socknum, sockets[socknum].fd, strerror(errno)); 1815 } 1816 return -1; 1817 } 1818 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1819 fatal_fr(r, "consume"); 1820 return 0; 1821 } 1822 1823 static void 1824 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1825 { 1826 size_t i; 1827 u_int socknum, activefds = npfd; 1828 1829 for (i = 0; i < npfd; i++) { 1830 if (pfd[i].revents == 0) 1831 continue; 1832 /* Find sockets entry */ 1833 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1834 if (sockets[socknum].type != AUTH_SOCKET && 1835 sockets[socknum].type != AUTH_CONNECTION) 1836 continue; 1837 if (pfd[i].fd == sockets[socknum].fd) 1838 break; 1839 } 1840 if (socknum >= sockets_alloc) { 1841 error_f("no socket for fd %d", pfd[i].fd); 1842 continue; 1843 } 1844 /* Process events */ 1845 switch (sockets[socknum].type) { 1846 case AUTH_SOCKET: 1847 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1848 break; 1849 if (npfd > maxfds) { 1850 debug3("out of fds (active %u >= limit %u); " 1851 "skipping accept", activefds, maxfds); 1852 break; 1853 } 1854 if (handle_socket_read(socknum) == 0) 1855 activefds++; 1856 break; 1857 case AUTH_CONNECTION: 1858 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1859 handle_conn_read(socknum) != 0) 1860 goto close_sock; 1861 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1862 handle_conn_write(socknum) != 0) { 1863 close_sock: 1864 if (activefds == 0) 1865 fatal("activefds == 0 at close_sock"); 1866 close_socket(&sockets[socknum]); 1867 activefds--; 1868 break; 1869 } 1870 break; 1871 default: 1872 break; 1873 } 1874 } 1875 } 1876 1877 static int 1878 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1879 { 1880 struct pollfd *pfd = *pfdp; 1881 size_t i, j, npfd = 0; 1882 time_t deadline; 1883 int r; 1884 1885 /* Count active sockets */ 1886 for (i = 0; i < sockets_alloc; i++) { 1887 switch (sockets[i].type) { 1888 case AUTH_SOCKET: 1889 case AUTH_CONNECTION: 1890 npfd++; 1891 break; 1892 case AUTH_UNUSED: 1893 break; 1894 default: 1895 fatal("Unknown socket type %d", sockets[i].type); 1896 break; 1897 } 1898 } 1899 if (npfd != *npfdp && 1900 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1901 fatal_f("recallocarray failed"); 1902 *pfdp = pfd; 1903 *npfdp = npfd; 1904 1905 for (i = j = 0; i < sockets_alloc; i++) { 1906 switch (sockets[i].type) { 1907 case AUTH_SOCKET: 1908 if (npfd > maxfds) { 1909 debug3("out of fds (active %zu >= limit %u); " 1910 "skipping arming listener", npfd, maxfds); 1911 break; 1912 } 1913 pfd[j].fd = sockets[i].fd; 1914 pfd[j].revents = 0; 1915 pfd[j].events = POLLIN; 1916 j++; 1917 break; 1918 case AUTH_CONNECTION: 1919 pfd[j].fd = sockets[i].fd; 1920 pfd[j].revents = 0; 1921 /* 1922 * Only prepare to read if we can handle a full-size 1923 * input read buffer and enqueue a max size reply.. 1924 */ 1925 if ((r = sshbuf_check_reserve(sockets[i].input, 1926 AGENT_RBUF_LEN)) == 0 && 1927 (r = sshbuf_check_reserve(sockets[i].output, 1928 AGENT_MAX_LEN)) == 0) 1929 pfd[j].events = POLLIN; 1930 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1931 fatal_fr(r, "reserve"); 1932 if (sshbuf_len(sockets[i].output) > 0) 1933 pfd[j].events |= POLLOUT; 1934 j++; 1935 break; 1936 default: 1937 break; 1938 } 1939 } 1940 deadline = reaper(); 1941 if (parent_alive_interval != 0) 1942 deadline = (deadline == 0) ? parent_alive_interval : 1943 MINIMUM(deadline, parent_alive_interval); 1944 if (deadline == 0) { 1945 *timeoutp = -1; /* INFTIM */ 1946 } else { 1947 if (deadline > INT_MAX / 1000) 1948 *timeoutp = INT_MAX / 1000; 1949 else 1950 *timeoutp = deadline * 1000; 1951 } 1952 return (1); 1953 } 1954 1955 static void 1956 cleanup_socket(void) 1957 { 1958 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1959 return; 1960 debug_f("cleanup"); 1961 if (socket_name[0]) 1962 unlink(socket_name); 1963 if (socket_dir[0]) 1964 rmdir(socket_dir); 1965 } 1966 1967 void 1968 cleanup_exit(int i) 1969 { 1970 cleanup_socket(); 1971 _exit(i); 1972 } 1973 1974 /*ARGSUSED*/ 1975 __dead static void 1976 cleanup_handler(int sig) 1977 { 1978 cleanup_socket(); 1979 #ifdef ENABLE_PKCS11 1980 pkcs11_terminate(); 1981 #endif 1982 _exit(2); 1983 } 1984 1985 static void 1986 check_parent_exists(void) 1987 { 1988 /* 1989 * If our parent has exited then getppid() will return (pid_t)1, 1990 * so testing for that should be safe. 1991 */ 1992 if (parent_pid != -1 && getppid() != parent_pid) { 1993 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1994 cleanup_socket(); 1995 _exit(2); 1996 } 1997 } 1998 1999 __dead static void 2000 usage(void) 2001 { 2002 fprintf(stderr, 2003 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 2004 " [-O option] [-P allowed_providers] [-t life]\n" 2005 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2006 " [-P allowed_providers] [-t life] command [arg ...]\n" 2007 " ssh-agent [-c | -s] -k\n"); 2008 exit(1); 2009 } 2010 2011 static void 2012 csh_setenv(const char *name, const char *value) 2013 { 2014 printf("setenv %s %s;\n", name, value); 2015 } 2016 2017 static void 2018 csh_unsetenv(const char *name) 2019 { 2020 printf("unsetenv %s;\n", name); 2021 } 2022 2023 static void 2024 sh_setenv(const char *name, const char *value) 2025 { 2026 printf("%s=%s; export %s;\n", name, value, name); 2027 } 2028 2029 static void 2030 sh_unsetenv(const char *name) 2031 { 2032 printf("unset %s;\n", name); 2033 } 2034 int 2035 main(int ac, char **av) 2036 { 2037 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2038 int sock, ch, result, saved_errno; 2039 char *shell, *pidstr, *agentsocket = NULL; 2040 struct rlimit rlim; 2041 void (*f_setenv)(const char *, const char *); 2042 void (*f_unsetenv)(const char *); 2043 extern int optind; 2044 extern char *optarg; 2045 pid_t pid; 2046 char pidstrbuf[1 + 3 * sizeof pid]; 2047 size_t len; 2048 mode_t prev_mask; 2049 int timeout = -1; /* INFTIM */ 2050 struct pollfd *pfd = NULL; 2051 size_t npfd = 0; 2052 u_int maxfds; 2053 2054 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2055 sanitise_stdfd(); 2056 2057 /* drop */ 2058 (void)setegid(getgid()); 2059 (void)setgid(getgid()); 2060 2061 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2062 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2063 2064 #ifdef WITH_OPENSSL 2065 OpenSSL_add_all_algorithms(); 2066 #endif 2067 2068 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2069 switch (ch) { 2070 case 'E': 2071 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2072 if (fingerprint_hash == -1) 2073 fatal("Invalid hash algorithm \"%s\"", optarg); 2074 break; 2075 case 'c': 2076 if (s_flag) 2077 usage(); 2078 c_flag++; 2079 break; 2080 case 'k': 2081 k_flag++; 2082 break; 2083 case 'O': 2084 if (strcmp(optarg, "no-restrict-websafe") == 0) 2085 restrict_websafe = 0; 2086 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2087 remote_add_provider = 1; 2088 else 2089 fatal("Unknown -O option"); 2090 break; 2091 case 'P': 2092 if (allowed_providers != NULL) 2093 fatal("-P option already specified"); 2094 allowed_providers = xstrdup(optarg); 2095 break; 2096 case 's': 2097 if (c_flag) 2098 usage(); 2099 s_flag++; 2100 break; 2101 case 'd': 2102 if (d_flag || D_flag) 2103 usage(); 2104 d_flag++; 2105 break; 2106 case 'D': 2107 if (d_flag || D_flag) 2108 usage(); 2109 D_flag++; 2110 break; 2111 case 'a': 2112 agentsocket = optarg; 2113 break; 2114 case 't': 2115 if ((lifetime = convtime(optarg)) == -1) { 2116 fprintf(stderr, "Invalid lifetime\n"); 2117 usage(); 2118 } 2119 break; 2120 default: 2121 usage(); 2122 } 2123 } 2124 ac -= optind; 2125 av += optind; 2126 2127 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2128 usage(); 2129 2130 if (allowed_providers == NULL) 2131 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2132 2133 if (ac == 0 && !c_flag && !s_flag) { 2134 shell = getenv("SHELL"); 2135 if (shell != NULL && (len = strlen(shell)) > 2 && 2136 strncmp(shell + len - 3, "csh", 3) == 0) 2137 c_flag = 1; 2138 } 2139 if (c_flag) { 2140 f_setenv = csh_setenv; 2141 f_unsetenv = csh_unsetenv; 2142 } else { 2143 f_setenv = sh_setenv; 2144 f_unsetenv = sh_unsetenv; 2145 } 2146 if (k_flag) { 2147 const char *errstr = NULL; 2148 2149 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2150 if (pidstr == NULL) { 2151 fprintf(stderr, "%s not set, cannot kill agent\n", 2152 SSH_AGENTPID_ENV_NAME); 2153 exit(1); 2154 } 2155 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2156 if (errstr) { 2157 fprintf(stderr, 2158 "%s=\"%s\", which is not a good PID: %s\n", 2159 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2160 exit(1); 2161 } 2162 if (kill(pid, SIGTERM) == -1) { 2163 perror("kill"); 2164 exit(1); 2165 } 2166 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 2167 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 2168 printf("echo Agent pid %ld killed;\n", (long)pid); 2169 exit(0); 2170 } 2171 2172 /* 2173 * Minimum file descriptors: 2174 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2175 * a few spare for libc / stack protectors / sanitisers, etc. 2176 */ 2177 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2178 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2179 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2180 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2181 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2182 2183 parent_pid = getpid(); 2184 2185 if (agentsocket == NULL) { 2186 /* Create private directory for agent socket */ 2187 mktemp_proto(socket_dir, sizeof(socket_dir)); 2188 if (mkdtemp(socket_dir) == NULL) { 2189 perror("mkdtemp: private socket dir"); 2190 exit(1); 2191 } 2192 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2193 (long)parent_pid); 2194 } else { 2195 /* Try to use specified agent socket */ 2196 socket_dir[0] = '\0'; 2197 strlcpy(socket_name, agentsocket, sizeof socket_name); 2198 } 2199 2200 /* 2201 * Create socket early so it will exist before command gets run from 2202 * the parent. 2203 */ 2204 prev_mask = umask(0177); 2205 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2206 if (sock < 0) { 2207 /* XXX - unix_listener() calls error() not perror() */ 2208 *socket_name = '\0'; /* Don't unlink any existing file */ 2209 cleanup_exit(1); 2210 } 2211 umask(prev_mask); 2212 2213 /* 2214 * Fork, and have the parent execute the command, if any, or present 2215 * the socket data. The child continues as the authentication agent. 2216 */ 2217 if (D_flag || d_flag) { 2218 log_init(__progname, 2219 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2220 SYSLOG_FACILITY_AUTH, 1); 2221 if (c_flag) 2222 printf("setenv %s %s;\n", 2223 SSH_AUTHSOCKET_ENV_NAME, socket_name); 2224 else 2225 printf("%s=%s; export %s;\n", 2226 SSH_AUTHSOCKET_ENV_NAME, socket_name, 2227 SSH_AUTHSOCKET_ENV_NAME); 2228 printf("echo Agent pid %ld;\n", (long)parent_pid); 2229 fflush(stdout); 2230 goto skip; 2231 } 2232 pid = fork(); 2233 if (pid == -1) { 2234 perror("fork"); 2235 cleanup_exit(1); 2236 } 2237 if (pid != 0) { /* Parent - execute the given command. */ 2238 close(sock); 2239 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2240 if (ac == 0) { 2241 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 2242 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 2243 printf("echo Agent pid %ld;\n", (long)pid); 2244 exit(0); 2245 } 2246 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2247 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2248 perror("setenv"); 2249 exit(1); 2250 } 2251 execvp(av[0], av); 2252 perror(av[0]); 2253 exit(1); 2254 } 2255 /* child */ 2256 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2257 2258 if (setsid() == -1) { 2259 error("setsid: %s", strerror(errno)); 2260 cleanup_exit(1); 2261 } 2262 2263 (void)chdir("/"); 2264 if (stdfd_devnull(1, 1, 1) == -1) 2265 error_f("stdfd_devnull failed"); 2266 2267 /* deny core dumps, since memory contains unencrypted private keys */ 2268 rlim.rlim_cur = rlim.rlim_max = 0; 2269 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2270 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2271 cleanup_exit(1); 2272 } 2273 2274 skip: 2275 2276 cleanup_pid = getpid(); 2277 2278 #ifdef ENABLE_PKCS11 2279 pkcs11_init(0); 2280 #endif 2281 new_socket(AUTH_SOCKET, sock); 2282 if (ac > 0) 2283 parent_alive_interval = 10; 2284 idtab_init(); 2285 ssh_signal(SIGPIPE, SIG_IGN); 2286 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2287 ssh_signal(SIGHUP, cleanup_handler); 2288 ssh_signal(SIGTERM, cleanup_handler); 2289 2290 #ifdef __OpenBSD__ 2291 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2292 fatal("%s: pledge: %s", __progname, strerror(errno)); 2293 #endif 2294 2295 while (1) { 2296 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2297 result = poll(pfd, npfd, timeout); 2298 saved_errno = errno; 2299 if (parent_alive_interval != 0) 2300 check_parent_exists(); 2301 (void) reaper(); /* remove expired keys */ 2302 if (result == -1) { 2303 if (saved_errno == EINTR) 2304 continue; 2305 fatal("poll: %s", strerror(saved_errno)); 2306 } else if (result > 0) 2307 after_poll(pfd, npfd, maxfds); 2308 } 2309 /* NOTREACHED */ 2310 } 2311