1 /* $NetBSD: ssh-agent.c,v 1.35 2023/07/26 17:58:15 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.297 2023/03/09 21:06:24 jcs Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * The authentication agent program. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 __RCSID("$NetBSD: ssh-agent.c,v 1.35 2023/07/26 17:58:15 christos Exp $"); 40 41 #include <sys/param.h> /* MIN MAX */ 42 #include <sys/types.h> 43 #include <sys/time.h> 44 #include <sys/queue.h> 45 #include <sys/resource.h> 46 #include <sys/socket.h> 47 #include <sys/stat.h> 48 #include <sys/un.h> 49 #include <sys/wait.h> 50 51 #ifdef WITH_OPENSSL 52 #include <openssl/evp.h> 53 #endif 54 55 #include <errno.h> 56 #include <fcntl.h> 57 #include <paths.h> 58 #include <poll.h> 59 #include <signal.h> 60 #include <stdlib.h> 61 #include <stdio.h> 62 #include <string.h> 63 #include <stdarg.h> 64 #include <limits.h> 65 #include <time.h> 66 #include <unistd.h> 67 #include <util.h> 68 69 #include "xmalloc.h" 70 #include "ssh.h" 71 #include "ssh2.h" 72 #include "sshbuf.h" 73 #include "sshkey.h" 74 #include "authfd.h" 75 #include "log.h" 76 #include "misc.h" 77 #include "getpeereid.h" 78 #include "digest.h" 79 #include "ssherr.h" 80 #include "match.h" 81 #include "msg.h" 82 #include "pathnames.h" 83 #include "ssh-pkcs11.h" 84 #include "sk-api.h" 85 #include "myproposal.h" 86 87 #ifndef DEFAULT_ALLOWED_PROVIDERS 88 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/pkg/lib*/*" 89 #endif 90 91 /* Maximum accepted message length */ 92 #define AGENT_MAX_LEN (256*1024) 93 /* Maximum bytes to read from client socket */ 94 #define AGENT_RBUF_LEN (4096) 95 /* Maximum number of recorded session IDs/hostkeys per connection */ 96 #define AGENT_MAX_SESSION_IDS 16 97 /* Maximum size of session ID */ 98 #define AGENT_MAX_SID_LEN 128 99 /* Maximum number of destination constraints to accept on a key */ 100 #define AGENT_MAX_DEST_CONSTRAINTS 1024 101 102 /* XXX store hostkey_sid in a refcounted tree */ 103 104 typedef enum { 105 AUTH_UNUSED = 0, 106 AUTH_SOCKET = 1, 107 AUTH_CONNECTION = 2, 108 } sock_type; 109 110 struct hostkey_sid { 111 struct sshkey *key; 112 struct sshbuf *sid; 113 int forwarded; 114 }; 115 116 typedef struct socket_entry { 117 int fd; 118 sock_type type; 119 struct sshbuf *input; 120 struct sshbuf *output; 121 struct sshbuf *request; 122 size_t nsession_ids; 123 struct hostkey_sid *session_ids; 124 } SocketEntry; 125 126 u_int sockets_alloc = 0; 127 SocketEntry *sockets = NULL; 128 129 typedef struct identity { 130 TAILQ_ENTRY(identity) next; 131 struct sshkey *key; 132 char *comment; 133 char *provider; 134 time_t death; 135 u_int confirm; 136 char *sk_provider; 137 struct dest_constraint *dest_constraints; 138 size_t ndest_constraints; 139 } Identity; 140 141 struct idtable { 142 int nentries; 143 TAILQ_HEAD(idqueue, identity) idlist; 144 }; 145 146 /* private key table */ 147 struct idtable *idtab; 148 149 int max_fd = 0; 150 151 /* pid of shell == parent of agent */ 152 pid_t parent_pid = -1; 153 time_t parent_alive_interval = 0; 154 155 /* pid of process for which cleanup_socket is applicable */ 156 pid_t cleanup_pid = 0; 157 158 /* pathname and directory for AUTH_SOCKET */ 159 char socket_name[PATH_MAX]; 160 char socket_dir[PATH_MAX]; 161 162 /* Pattern-list of allowed PKCS#11/Security key paths */ 163 static char *allowed_providers; 164 165 /* 166 * Allows PKCS11 providers or SK keys that use non-internal providers to 167 * be added over a remote connection (identified by session-bind@openssh.com). 168 */ 169 static int remote_add_provider; 170 171 /* locking */ 172 #define LOCK_SIZE 32 173 #define LOCK_SALT_SIZE 16 174 #define LOCK_ROUNDS 1 175 int locked = 0; 176 u_char lock_pwhash[LOCK_SIZE]; 177 u_char lock_salt[LOCK_SALT_SIZE]; 178 179 extern char *__progname; 180 181 /* Default lifetime in seconds (0 == forever) */ 182 static int lifetime = 0; 183 184 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 185 186 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 187 static int restrict_websafe = 1; 188 189 static void 190 close_socket(SocketEntry *e) 191 { 192 size_t i; 193 194 close(e->fd); 195 sshbuf_free(e->input); 196 sshbuf_free(e->output); 197 sshbuf_free(e->request); 198 for (i = 0; i < e->nsession_ids; i++) { 199 sshkey_free(e->session_ids[i].key); 200 sshbuf_free(e->session_ids[i].sid); 201 } 202 free(e->session_ids); 203 memset(e, '\0', sizeof(*e)); 204 e->fd = -1; 205 e->type = AUTH_UNUSED; 206 } 207 208 static void 209 idtab_init(void) 210 { 211 idtab = xcalloc(1, sizeof(*idtab)); 212 TAILQ_INIT(&idtab->idlist); 213 idtab->nentries = 0; 214 } 215 216 static void 217 free_dest_constraint_hop(struct dest_constraint_hop *dch) 218 { 219 u_int i; 220 221 if (dch == NULL) 222 return; 223 free(dch->user); 224 free(dch->hostname); 225 for (i = 0; i < dch->nkeys; i++) 226 sshkey_free(dch->keys[i]); 227 free(dch->keys); 228 free(dch->key_is_ca); 229 } 230 231 static void 232 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 233 { 234 size_t i; 235 236 for (i = 0; i < ndcs; i++) { 237 free_dest_constraint_hop(&dcs[i].from); 238 free_dest_constraint_hop(&dcs[i].to); 239 } 240 free(dcs); 241 } 242 243 static void 244 free_identity(Identity *id) 245 { 246 sshkey_free(id->key); 247 free(id->provider); 248 free(id->comment); 249 free(id->sk_provider); 250 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 251 free(id); 252 } 253 254 /* 255 * Match 'key' against the key/CA list in a destination constraint hop 256 * Returns 0 on success or -1 otherwise. 257 */ 258 static int 259 match_key_hop(const char *tag, const struct sshkey *key, 260 const struct dest_constraint_hop *dch) 261 { 262 const char *reason = NULL; 263 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 264 u_int i; 265 char *fp; 266 267 if (key == NULL) 268 return -1; 269 /* XXX logspam */ 270 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 271 SSH_FP_DEFAULT)) == NULL) 272 fatal_f("fingerprint failed"); 273 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 274 tag, hostname, sshkey_type(key), fp, dch->nkeys); 275 free(fp); 276 for (i = 0; i < dch->nkeys; i++) { 277 if (dch->keys[i] == NULL) 278 return -1; 279 /* XXX logspam */ 280 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 281 SSH_FP_DEFAULT)) == NULL) 282 fatal_f("fingerprint failed"); 283 debug3_f("%s: key %u: %s%s %s", tag, i, 284 dch->key_is_ca[i] ? "CA " : "", 285 sshkey_type(dch->keys[i]), fp); 286 free(fp); 287 if (!sshkey_is_cert(key)) { 288 /* plain key */ 289 if (dch->key_is_ca[i] || 290 !sshkey_equal(key, dch->keys[i])) 291 continue; 292 return 0; 293 } 294 /* certificate */ 295 if (!dch->key_is_ca[i]) 296 continue; 297 if (key->cert == NULL || key->cert->signature_key == NULL) 298 return -1; /* shouldn't happen */ 299 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 300 continue; 301 if (sshkey_cert_check_host(key, hostname, 1, 302 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 303 debug_f("cert %s / hostname %s rejected: %s", 304 key->cert->key_id, hostname, reason); 305 continue; 306 } 307 return 0; 308 } 309 return -1; 310 } 311 312 /* Check destination constraints on an identity against the hostkey/user */ 313 static int 314 permitted_by_dest_constraints(const struct sshkey *fromkey, 315 const struct sshkey *tokey, Identity *id, const char *user, 316 const char **hostnamep) 317 { 318 size_t i; 319 struct dest_constraint *d; 320 321 if (hostnamep != NULL) 322 *hostnamep = NULL; 323 for (i = 0; i < id->ndest_constraints; i++) { 324 d = id->dest_constraints + i; 325 /* XXX remove logspam */ 326 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 327 i, d->from.user ? d->from.user : "", 328 d->from.user ? "@" : "", 329 d->from.hostname ? d->from.hostname : "(ORIGIN)", 330 d->from.nkeys, 331 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 332 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 333 334 /* Match 'from' key */ 335 if (fromkey == NULL) { 336 /* We are matching the first hop */ 337 if (d->from.hostname != NULL || d->from.nkeys != 0) 338 continue; 339 } else if (match_key_hop("from", fromkey, &d->from) != 0) 340 continue; 341 342 /* Match 'to' key */ 343 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 344 continue; 345 346 /* Match user if specified */ 347 if (d->to.user != NULL && user != NULL && 348 !match_pattern(user, d->to.user)) 349 continue; 350 351 /* successfully matched this constraint */ 352 if (hostnamep != NULL) 353 *hostnamep = d->to.hostname; 354 debug2_f("allowed for hostname %s", 355 d->to.hostname == NULL ? "*" : d->to.hostname); 356 return 0; 357 } 358 /* no match */ 359 debug2_f("%s identity \"%s\" not permitted for this destination", 360 sshkey_type(id->key), id->comment); 361 return -1; 362 } 363 364 /* 365 * Check whether hostkeys on a SocketEntry and the optionally specified user 366 * are permitted by the destination constraints on the Identity. 367 * Returns 0 on success or -1 otherwise. 368 */ 369 static int 370 identity_permitted(Identity *id, SocketEntry *e, char *user, 371 const char **forward_hostnamep, const char **last_hostnamep) 372 { 373 size_t i; 374 const char **hp; 375 struct hostkey_sid *hks; 376 const struct sshkey *fromkey = NULL; 377 const char *test_user; 378 char *fp1, *fp2; 379 380 /* XXX remove logspam */ 381 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 382 "%zu constraints", sshkey_type(id->key), id->comment, 383 e->nsession_ids, id->ndest_constraints); 384 if (id->ndest_constraints == 0) 385 return 0; /* unconstrained */ 386 if (e->nsession_ids == 0) 387 return 0; /* local use */ 388 /* 389 * Walk through the hops recorded by session_id and try to find a 390 * constraint that satisfies each. 391 */ 392 for (i = 0; i < e->nsession_ids; i++) { 393 hks = e->session_ids + i; 394 if (hks->key == NULL) 395 fatal_f("internal error: no bound key"); 396 /* XXX remove logspam */ 397 fp1 = fp2 = NULL; 398 if (fromkey != NULL && 399 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 400 SSH_FP_DEFAULT)) == NULL) 401 fatal_f("fingerprint failed"); 402 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 403 SSH_FP_DEFAULT)) == NULL) 404 fatal_f("fingerprint failed"); 405 debug3_f("socketentry fd=%d, entry %zu %s, " 406 "from hostkey %s %s to user %s hostkey %s %s", 407 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 408 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 409 fromkey ? fp1 : "", user ? user : "(ANY)", 410 sshkey_type(hks->key), fp2); 411 free(fp1); 412 free(fp2); 413 /* 414 * Record the hostnames for the initial forwarding and 415 * the final destination. 416 */ 417 hp = NULL; 418 if (i == e->nsession_ids - 1) 419 hp = last_hostnamep; 420 else if (i == 0) 421 hp = forward_hostnamep; 422 /* Special handling for final recorded binding */ 423 test_user = NULL; 424 if (i == e->nsession_ids - 1) { 425 /* Can only check user at final hop */ 426 test_user = user; 427 /* 428 * user is only presented for signature requests. 429 * If this is the case, make sure last binding is not 430 * for a forwarding. 431 */ 432 if (hks->forwarded && user != NULL) { 433 error_f("tried to sign on forwarding hop"); 434 return -1; 435 } 436 } else if (!hks->forwarded) { 437 error_f("tried to forward though signing bind"); 438 return -1; 439 } 440 if (permitted_by_dest_constraints(fromkey, hks->key, id, 441 test_user, hp) != 0) 442 return -1; 443 fromkey = hks->key; 444 } 445 /* 446 * Another special case: if the last bound session ID was for a 447 * forwarding, and this function is not being called to check a sign 448 * request (i.e. no 'user' supplied), then only permit the key if 449 * there is a permission that would allow it to be used at another 450 * destination. This hides keys that are allowed to be used to 451 * authenticate *to* a host but not permitted for *use* beyond it. 452 */ 453 hks = &e->session_ids[e->nsession_ids - 1]; 454 if (hks->forwarded && user == NULL && 455 permitted_by_dest_constraints(hks->key, NULL, id, 456 NULL, NULL) != 0) { 457 debug3_f("key permitted at host but not after"); 458 return -1; 459 } 460 461 /* success */ 462 return 0; 463 } 464 465 /* return matching private key for given public key */ 466 static Identity * 467 lookup_identity(struct sshkey *key) 468 { 469 Identity *id; 470 471 TAILQ_FOREACH(id, &idtab->idlist, next) { 472 if (sshkey_equal(key, id->key)) 473 return (id); 474 } 475 return (NULL); 476 } 477 478 /* Check confirmation of keysign request */ 479 static int 480 confirm_key(Identity *id, const char *extra) 481 { 482 char *p; 483 int ret = -1; 484 485 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 486 if (p != NULL && 487 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 488 id->comment, p, 489 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 490 ret = 0; 491 free(p); 492 493 return (ret); 494 } 495 496 static void 497 send_status(SocketEntry *e, int success) 498 { 499 int r; 500 501 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 502 (r = sshbuf_put_u8(e->output, success ? 503 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 504 fatal_fr(r, "compose"); 505 } 506 507 /* send list of supported public keys to 'client' */ 508 static void 509 process_request_identities(SocketEntry *e) 510 { 511 Identity *id; 512 struct sshbuf *msg, *keys; 513 int r; 514 u_int nentries = 0; 515 516 debug2_f("entering"); 517 518 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 519 fatal_f("sshbuf_new failed"); 520 TAILQ_FOREACH(id, &idtab->idlist, next) { 521 /* identity not visible, don't include in response */ 522 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 523 continue; 524 if ((r = sshkey_puts_opts(id->key, keys, 525 SSHKEY_SERIALIZE_INFO)) != 0 || 526 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 527 error_fr(r, "compose key/comment"); 528 continue; 529 } 530 nentries++; 531 } 532 debug2_f("replying with %u allowed of %u available keys", 533 nentries, idtab->nentries); 534 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 535 (r = sshbuf_put_u32(msg, nentries)) != 0 || 536 (r = sshbuf_putb(msg, keys)) != 0) 537 fatal_fr(r, "compose"); 538 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 539 fatal_fr(r, "enqueue"); 540 sshbuf_free(msg); 541 sshbuf_free(keys); 542 } 543 544 545 static const char * 546 agent_decode_alg(struct sshkey *key, u_int flags) 547 { 548 if (key->type == KEY_RSA) { 549 if (flags & SSH_AGENT_RSA_SHA2_256) 550 return "rsa-sha2-256"; 551 else if (flags & SSH_AGENT_RSA_SHA2_512) 552 return "rsa-sha2-512"; 553 } else if (key->type == KEY_RSA_CERT) { 554 if (flags & SSH_AGENT_RSA_SHA2_256) 555 return "rsa-sha2-256-cert-v01@openssh.com"; 556 else if (flags & SSH_AGENT_RSA_SHA2_512) 557 return "rsa-sha2-512-cert-v01@openssh.com"; 558 } 559 return NULL; 560 } 561 562 /* 563 * Attempt to parse the contents of a buffer as a SSH publickey userauth 564 * request, checking its contents for consistency and matching the embedded 565 * key against the one that is being used for signing. 566 * Note: does not modify msg buffer. 567 * Optionally extract the username, session ID and/or hostkey from the request. 568 */ 569 static int 570 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 571 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 572 { 573 struct sshbuf *b = NULL, *sess_id = NULL; 574 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 575 int r; 576 u_char t, sig_follows; 577 struct sshkey *mkey = NULL, *hostkey = NULL; 578 579 if (userp != NULL) 580 *userp = NULL; 581 if (sess_idp != NULL) 582 *sess_idp = NULL; 583 if (hostkeyp != NULL) 584 *hostkeyp = NULL; 585 if ((b = sshbuf_fromb(msg)) == NULL) 586 fatal_f("sshbuf_fromb"); 587 588 /* SSH userauth request */ 589 if ((r = sshbuf_froms(b, &sess_id)) != 0) 590 goto out; 591 if (sshbuf_len(sess_id) == 0) { 592 r = SSH_ERR_INVALID_FORMAT; 593 goto out; 594 } 595 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 596 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 597 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 598 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 599 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 600 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 601 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 602 goto out; 603 if (t != SSH2_MSG_USERAUTH_REQUEST || 604 sig_follows != 1 || 605 strcmp(service, "ssh-connection") != 0 || 606 !sshkey_equal(expected_key, mkey) || 607 sshkey_type_from_name(pkalg) != expected_key->type) { 608 r = SSH_ERR_INVALID_FORMAT; 609 goto out; 610 } 611 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 612 if ((r = sshkey_froms(b, &hostkey)) != 0) 613 goto out; 614 } else if (strcmp(method, "publickey") != 0) { 615 r = SSH_ERR_INVALID_FORMAT; 616 goto out; 617 } 618 if (sshbuf_len(b) != 0) { 619 r = SSH_ERR_INVALID_FORMAT; 620 goto out; 621 } 622 /* success */ 623 r = 0; 624 debug3_f("well formed userauth"); 625 if (userp != NULL) { 626 *userp = user; 627 user = NULL; 628 } 629 if (sess_idp != NULL) { 630 *sess_idp = sess_id; 631 sess_id = NULL; 632 } 633 if (hostkeyp != NULL) { 634 *hostkeyp = hostkey; 635 hostkey = NULL; 636 } 637 out: 638 sshbuf_free(b); 639 sshbuf_free(sess_id); 640 free(user); 641 free(service); 642 free(method); 643 free(pkalg); 644 sshkey_free(mkey); 645 sshkey_free(hostkey); 646 return r; 647 } 648 649 /* 650 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 651 * Note: does not modify buffer. 652 */ 653 static int 654 parse_sshsig_request(struct sshbuf *msg) 655 { 656 int r; 657 struct sshbuf *b; 658 659 if ((b = sshbuf_fromb(msg)) == NULL) 660 fatal_f("sshbuf_fromb"); 661 662 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 663 (r = sshbuf_consume(b, 6)) != 0 || 664 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 665 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 666 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 667 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 668 goto out; 669 if (sshbuf_len(b) != 0) { 670 r = SSH_ERR_INVALID_FORMAT; 671 goto out; 672 } 673 /* success */ 674 r = 0; 675 out: 676 sshbuf_free(b); 677 return r; 678 } 679 680 /* 681 * This function inspects a message to be signed by a FIDO key that has a 682 * web-like application string (i.e. one that does not begin with "ssh:". 683 * It checks that the message is one of those expected for SSH operations 684 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 685 * for the web. 686 */ 687 static int 688 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 689 { 690 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 691 debug_f("signed data matches public key userauth request"); 692 return 1; 693 } 694 if (parse_sshsig_request(data) == 0) { 695 debug_f("signed data matches SSHSIG signature request"); 696 return 1; 697 } 698 699 /* XXX check CA signature operation */ 700 701 error("web-origin key attempting to sign non-SSH message"); 702 return 0; 703 } 704 705 static int 706 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 707 { 708 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 709 return SSH_ERR_INVALID_ARGUMENT; 710 if (sshbuf_len(a) != sshbuf_len(b)) 711 return SSH_ERR_INVALID_FORMAT; 712 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 713 return SSH_ERR_INVALID_FORMAT; 714 return 0; 715 } 716 717 /* ssh2 only */ 718 static void 719 process_sign_request2(SocketEntry *e) 720 { 721 u_char *signature = NULL; 722 size_t slen = 0; 723 u_int compat = 0, flags; 724 int r, ok = -1, retried = 0; 725 char *fp = NULL, *pin = NULL, *prompt = NULL; 726 char *user = NULL, *sig_dest = NULL; 727 const char *fwd_host = NULL, *dest_host = NULL; 728 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 729 struct sshkey *key = NULL, *hostkey = NULL; 730 struct identity *id; 731 struct notifier_ctx *notifier = NULL; 732 733 debug_f("entering"); 734 735 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 736 fatal_f("sshbuf_new failed"); 737 if ((r = sshkey_froms(e->request, &key)) != 0 || 738 (r = sshbuf_get_stringb(e->request, data)) != 0 || 739 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 740 error_fr(r, "parse"); 741 goto send; 742 } 743 744 if ((id = lookup_identity(key)) == NULL) { 745 verbose_f("%s key not found", sshkey_type(key)); 746 goto send; 747 } 748 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 749 SSH_FP_DEFAULT)) == NULL) 750 fatal_f("fingerprint failed"); 751 752 if (id->ndest_constraints != 0) { 753 if (e->nsession_ids == 0) { 754 logit_f("refusing use of destination-constrained key " 755 "to sign on unbound connection"); 756 goto send; 757 } 758 if (parse_userauth_request(data, key, &user, &sid, 759 &hostkey) != 0) { 760 logit_f("refusing use of destination-constrained key " 761 "to sign an unidentified signature"); 762 goto send; 763 } 764 /* XXX logspam */ 765 debug_f("user=%s", user); 766 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 767 goto send; 768 /* XXX display fwd_host/dest_host in askpass UI */ 769 /* 770 * Ensure that the session ID is the most recent one 771 * registered on the socket - it should have been bound by 772 * ssh immediately before userauth. 773 */ 774 if (buf_equal(sid, 775 e->session_ids[e->nsession_ids - 1].sid) != 0) { 776 error_f("unexpected session ID (%zu listed) on " 777 "signature request for target user %s with " 778 "key %s %s", e->nsession_ids, user, 779 sshkey_type(id->key), fp); 780 goto send; 781 } 782 /* 783 * Ensure that the hostkey embedded in the signature matches 784 * the one most recently bound to the socket. An exception is 785 * made for the initial forwarding hop. 786 */ 787 if (e->nsession_ids > 1 && hostkey == NULL) { 788 error_f("refusing use of destination-constrained key: " 789 "no hostkey recorded in signature for forwarded " 790 "connection"); 791 goto send; 792 } 793 if (hostkey != NULL && !sshkey_equal(hostkey, 794 e->session_ids[e->nsession_ids - 1].key)) { 795 error_f("refusing use of destination-constrained key: " 796 "mismatch between hostkey in request and most " 797 "recently bound session"); 798 goto send; 799 } 800 xasprintf(&sig_dest, "public key authentication request for " 801 "user \"%s\" to listed host", user); 802 } 803 if (id->confirm && confirm_key(id, sig_dest) != 0) { 804 verbose_f("user refused key"); 805 goto send; 806 } 807 if (sshkey_is_sk(id->key)) { 808 if (restrict_websafe && 809 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 810 !check_websafe_message_contents(key, data)) { 811 /* error already logged */ 812 goto send; 813 } 814 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 815 notifier = notify_start(0, 816 "Confirm user presence for key %s %s%s%s", 817 sshkey_type(id->key), fp, 818 sig_dest == NULL ? "" : "\n", 819 sig_dest == NULL ? "" : sig_dest); 820 } 821 } 822 retry_pin: 823 if ((r = sshkey_sign(id->key, &signature, &slen, 824 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 825 id->sk_provider, pin, compat)) != 0) { 826 debug_fr(r, "sshkey_sign"); 827 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 828 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 829 notify_complete(notifier, NULL); 830 notifier = NULL; 831 /* XXX include sig_dest */ 832 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 833 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 834 " and confirm user presence " : " ", 835 sshkey_type(id->key), fp); 836 pin = read_passphrase(prompt, RP_USE_ASKPASS); 837 retried = 1; 838 goto retry_pin; 839 } 840 error_fr(r, "sshkey_sign"); 841 goto send; 842 } 843 /* Success */ 844 ok = 0; 845 send: 846 debug_f("good signature"); 847 notify_complete(notifier, "User presence confirmed"); 848 849 if (ok == 0) { 850 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 851 (r = sshbuf_put_string(msg, signature, slen)) != 0) 852 fatal_fr(r, "compose"); 853 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 854 fatal_fr(r, "compose failure"); 855 856 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 857 fatal_fr(r, "enqueue"); 858 859 sshbuf_free(sid); 860 sshbuf_free(data); 861 sshbuf_free(msg); 862 sshkey_free(key); 863 sshkey_free(hostkey); 864 free(fp); 865 free(signature); 866 free(sig_dest); 867 free(user); 868 free(prompt); 869 if (pin != NULL) 870 freezero(pin, strlen(pin)); 871 } 872 873 /* shared */ 874 static void 875 process_remove_identity(SocketEntry *e) 876 { 877 int r, success = 0; 878 struct sshkey *key = NULL; 879 Identity *id; 880 881 debug2_f("entering"); 882 if ((r = sshkey_froms(e->request, &key)) != 0) { 883 error_fr(r, "parse key"); 884 goto done; 885 } 886 if ((id = lookup_identity(key)) == NULL) { 887 debug_f("key not found"); 888 goto done; 889 } 890 /* identity not visible, cannot be removed */ 891 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 892 goto done; /* error already logged */ 893 /* We have this key, free it. */ 894 if (idtab->nentries < 1) 895 fatal_f("internal error: nentries %d", idtab->nentries); 896 TAILQ_REMOVE(&idtab->idlist, id, next); 897 free_identity(id); 898 idtab->nentries--; 899 success = 1; 900 done: 901 sshkey_free(key); 902 send_status(e, success); 903 } 904 905 static void 906 process_remove_all_identities(SocketEntry *e) 907 { 908 Identity *id; 909 910 debug2_f("entering"); 911 /* Loop over all identities and clear the keys. */ 912 for (id = TAILQ_FIRST(&idtab->idlist); id; 913 id = TAILQ_FIRST(&idtab->idlist)) { 914 TAILQ_REMOVE(&idtab->idlist, id, next); 915 free_identity(id); 916 } 917 918 /* Mark that there are no identities. */ 919 idtab->nentries = 0; 920 921 /* Send success. */ 922 send_status(e, 1); 923 } 924 925 /* removes expired keys and returns number of seconds until the next expiry */ 926 static time_t 927 reaper(void) 928 { 929 time_t deadline = 0, now = monotime(); 930 Identity *id, *nxt; 931 932 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 933 nxt = TAILQ_NEXT(id, next); 934 if (id->death == 0) 935 continue; 936 if (now >= id->death) { 937 debug("expiring key '%s'", id->comment); 938 TAILQ_REMOVE(&idtab->idlist, id, next); 939 free_identity(id); 940 idtab->nentries--; 941 } else 942 deadline = (deadline == 0) ? id->death : 943 MINIMUM(deadline, id->death); 944 } 945 if (deadline == 0 || deadline <= now) 946 return 0; 947 else 948 return (deadline - now); 949 } 950 951 static int 952 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 953 { 954 u_char key_is_ca; 955 size_t elen = 0; 956 int r; 957 struct sshkey *k = NULL; 958 char *fp; 959 960 memset(dch, '\0', sizeof(*dch)); 961 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 962 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 963 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 964 error_fr(r, "parse"); 965 goto out; 966 } 967 if (elen != 0) { 968 error_f("unsupported extensions (len %zu)", elen); 969 r = SSH_ERR_FEATURE_UNSUPPORTED; 970 goto out; 971 } 972 if (*dch->hostname == '\0') { 973 free(dch->hostname); 974 dch->hostname = NULL; 975 } 976 if (*dch->user == '\0') { 977 free(dch->user); 978 dch->user = NULL; 979 } 980 while (sshbuf_len(b) != 0) { 981 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 982 dch->nkeys + 1, sizeof(*dch->keys)); 983 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 984 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 985 if ((r = sshkey_froms(b, &k)) != 0 || 986 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 987 goto out; 988 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 989 SSH_FP_DEFAULT)) == NULL) 990 fatal_f("fingerprint failed"); 991 debug3_f("%s%s%s: adding %skey %s %s", 992 dch->user == NULL ? "" : dch->user, 993 dch->user == NULL ? "" : "@", 994 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 995 free(fp); 996 dch->keys[dch->nkeys] = k; 997 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 998 dch->nkeys++; 999 k = NULL; /* transferred */ 1000 } 1001 /* success */ 1002 r = 0; 1003 out: 1004 sshkey_free(k); 1005 return r; 1006 } 1007 1008 static int 1009 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1010 { 1011 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1012 int r; 1013 size_t elen = 0; 1014 1015 debug3_f("entering"); 1016 1017 memset(dc, '\0', sizeof(*dc)); 1018 if ((r = sshbuf_froms(m, &b)) != 0 || 1019 (r = sshbuf_froms(b, &frombuf)) != 0 || 1020 (r = sshbuf_froms(b, &tobuf)) != 0 || 1021 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1022 error_fr(r, "parse"); 1023 goto out; 1024 } 1025 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1026 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1027 goto out; /* already logged */ 1028 if (elen != 0) { 1029 error_f("unsupported extensions (len %zu)", elen); 1030 r = SSH_ERR_FEATURE_UNSUPPORTED; 1031 goto out; 1032 } 1033 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1034 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1035 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1036 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1037 /* check consistency */ 1038 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1039 dc->from.user != NULL) { 1040 error_f("inconsistent \"from\" specification"); 1041 r = SSH_ERR_INVALID_FORMAT; 1042 goto out; 1043 } 1044 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1045 error_f("incomplete \"to\" specification"); 1046 r = SSH_ERR_INVALID_FORMAT; 1047 goto out; 1048 } 1049 /* success */ 1050 r = 0; 1051 out: 1052 sshbuf_free(b); 1053 sshbuf_free(frombuf); 1054 sshbuf_free(tobuf); 1055 return r; 1056 } 1057 1058 static int 1059 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1060 struct dest_constraint **dcsp, size_t *ndcsp) 1061 { 1062 char *ext_name = NULL; 1063 int r; 1064 struct sshbuf *b = NULL; 1065 1066 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1067 error_fr(r, "parse constraint extension"); 1068 goto out; 1069 } 1070 debug_f("constraint ext %s", ext_name); 1071 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1072 if (sk_providerp == NULL) { 1073 error_f("%s not valid here", ext_name); 1074 r = SSH_ERR_INVALID_FORMAT; 1075 goto out; 1076 } 1077 if (*sk_providerp != NULL) { 1078 error_f("%s already set", ext_name); 1079 r = SSH_ERR_INVALID_FORMAT; 1080 goto out; 1081 } 1082 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1083 error_fr(r, "parse %s", ext_name); 1084 goto out; 1085 } 1086 } else if (strcmp(ext_name, 1087 "restrict-destination-v00@openssh.com") == 0) { 1088 if (*dcsp != NULL) { 1089 error_f("%s already set", ext_name); 1090 goto out; 1091 } 1092 if ((r = sshbuf_froms(m, &b)) != 0) { 1093 error_fr(r, "parse %s outer", ext_name); 1094 goto out; 1095 } 1096 while (sshbuf_len(b) != 0) { 1097 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1098 error_f("too many %s constraints", ext_name); 1099 goto out; 1100 } 1101 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1102 sizeof(**dcsp)); 1103 if ((r = parse_dest_constraint(b, 1104 *dcsp + (*ndcsp)++)) != 0) 1105 goto out; /* error already logged */ 1106 } 1107 } else { 1108 error_f("unsupported constraint \"%s\"", ext_name); 1109 r = SSH_ERR_FEATURE_UNSUPPORTED; 1110 goto out; 1111 } 1112 /* success */ 1113 r = 0; 1114 out: 1115 free(ext_name); 1116 sshbuf_free(b); 1117 return r; 1118 } 1119 1120 static int 1121 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1122 u_int *secondsp, int *confirmp, char **sk_providerp, 1123 struct dest_constraint **dcsp, size_t *ndcsp) 1124 { 1125 u_char ctype; 1126 int r; 1127 u_int seconds, maxsign = 0; 1128 1129 while (sshbuf_len(m)) { 1130 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1131 error_fr(r, "parse constraint type"); 1132 goto out; 1133 } 1134 switch (ctype) { 1135 case SSH_AGENT_CONSTRAIN_LIFETIME: 1136 if (*deathp != 0) { 1137 error_f("lifetime already set"); 1138 r = SSH_ERR_INVALID_FORMAT; 1139 goto out; 1140 } 1141 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1142 error_fr(r, "parse lifetime constraint"); 1143 goto out; 1144 } 1145 *deathp = monotime() + seconds; 1146 *secondsp = seconds; 1147 break; 1148 case SSH_AGENT_CONSTRAIN_CONFIRM: 1149 if (*confirmp != 0) { 1150 error_f("confirm already set"); 1151 r = SSH_ERR_INVALID_FORMAT; 1152 goto out; 1153 } 1154 *confirmp = 1; 1155 break; 1156 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1157 if (k == NULL) { 1158 error_f("maxsign not valid here"); 1159 r = SSH_ERR_INVALID_FORMAT; 1160 goto out; 1161 } 1162 if (maxsign != 0) { 1163 error_f("maxsign already set"); 1164 r = SSH_ERR_INVALID_FORMAT; 1165 goto out; 1166 } 1167 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1168 error_fr(r, "parse maxsign constraint"); 1169 goto out; 1170 } 1171 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1172 error_fr(r, "enable maxsign"); 1173 goto out; 1174 } 1175 break; 1176 case SSH_AGENT_CONSTRAIN_EXTENSION: 1177 if ((r = parse_key_constraint_extension(m, 1178 sk_providerp, dcsp, ndcsp)) != 0) 1179 goto out; /* error already logged */ 1180 break; 1181 default: 1182 error_f("Unknown constraint %d", ctype); 1183 r = SSH_ERR_FEATURE_UNSUPPORTED; 1184 goto out; 1185 } 1186 } 1187 /* success */ 1188 r = 0; 1189 out: 1190 return r; 1191 } 1192 1193 static void 1194 process_add_identity(SocketEntry *e) 1195 { 1196 Identity *id; 1197 int success = 0, confirm = 0; 1198 char *fp, *comment = NULL, *sk_provider = NULL; 1199 char canonical_provider[PATH_MAX]; 1200 time_t death = 0; 1201 u_int seconds = 0; 1202 struct dest_constraint *dest_constraints = NULL; 1203 size_t ndest_constraints = 0; 1204 struct sshkey *k = NULL; 1205 int r = SSH_ERR_INTERNAL_ERROR; 1206 1207 debug2_f("entering"); 1208 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1209 k == NULL || 1210 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1211 error_fr(r, "parse"); 1212 goto out; 1213 } 1214 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1215 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1216 error_f("failed to parse constraints"); 1217 sshbuf_reset(e->request); 1218 goto out; 1219 } 1220 1221 if (sk_provider != NULL) { 1222 if (!sshkey_is_sk(k)) { 1223 error("Cannot add provider: %s is not an " 1224 "authenticator-hosted key", sshkey_type(k)); 1225 goto out; 1226 } 1227 if (strcasecmp(sk_provider, "internal") == 0) { 1228 debug_f("internal provider"); 1229 } else { 1230 if (e->nsession_ids != 0 && !remote_add_provider) { 1231 verbose("failed add of SK provider \"%.100s\": " 1232 "remote addition of providers is disabled", 1233 sk_provider); 1234 goto out; 1235 } 1236 if (realpath(sk_provider, canonical_provider) == NULL) { 1237 verbose("failed provider \"%.100s\": " 1238 "realpath: %s", sk_provider, 1239 strerror(errno)); 1240 goto out; 1241 } 1242 free(sk_provider); 1243 sk_provider = xstrdup(canonical_provider); 1244 if (match_pattern_list(sk_provider, 1245 allowed_providers, 0) != 1) { 1246 error("Refusing add key: " 1247 "provider %s not allowed", sk_provider); 1248 goto out; 1249 } 1250 } 1251 } 1252 if ((r = sshkey_shield_private(k)) != 0) { 1253 error_fr(r, "shield private"); 1254 goto out; 1255 } 1256 if (lifetime && !death) 1257 death = monotime() + lifetime; 1258 if ((id = lookup_identity(k)) == NULL) { 1259 id = xcalloc(1, sizeof(Identity)); 1260 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1261 /* Increment the number of identities. */ 1262 idtab->nentries++; 1263 } else { 1264 /* identity not visible, do not update */ 1265 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1266 goto out; /* error already logged */ 1267 /* key state might have been updated */ 1268 sshkey_free(id->key); 1269 free(id->comment); 1270 free(id->sk_provider); 1271 free_dest_constraints(id->dest_constraints, 1272 id->ndest_constraints); 1273 } 1274 /* success */ 1275 id->key = k; 1276 id->comment = comment; 1277 id->death = death; 1278 id->confirm = confirm; 1279 id->sk_provider = sk_provider; 1280 id->dest_constraints = dest_constraints; 1281 id->ndest_constraints = ndest_constraints; 1282 1283 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1284 SSH_FP_DEFAULT)) == NULL) 1285 fatal_f("sshkey_fingerprint failed"); 1286 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1287 "(provider: %s) (destination constraints: %zu)", 1288 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1289 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1290 free(fp); 1291 /* transferred */ 1292 k = NULL; 1293 comment = NULL; 1294 sk_provider = NULL; 1295 dest_constraints = NULL; 1296 ndest_constraints = 0; 1297 success = 1; 1298 out: 1299 free(sk_provider); 1300 free(comment); 1301 sshkey_free(k); 1302 free_dest_constraints(dest_constraints, ndest_constraints); 1303 send_status(e, success); 1304 } 1305 1306 /* XXX todo: encrypt sensitive data with passphrase */ 1307 static void 1308 process_lock_agent(SocketEntry *e, int lock) 1309 { 1310 int r, success = 0, delay; 1311 char *passwd; 1312 u_char passwdhash[LOCK_SIZE]; 1313 static u_int fail_count = 0; 1314 size_t pwlen; 1315 1316 debug2_f("entering"); 1317 /* 1318 * This is deliberately fatal: the user has requested that we lock, 1319 * but we can't parse their request properly. The only safe thing to 1320 * do is abort. 1321 */ 1322 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1323 fatal_fr(r, "parse"); 1324 if (pwlen == 0) { 1325 debug("empty password not supported"); 1326 } else if (locked && !lock) { 1327 if (bcrypt_pbkdf(passwd, pwlen, (uint8_t *)lock_salt, sizeof(lock_salt), 1328 (uint8_t *)passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1329 fatal("bcrypt_pbkdf"); 1330 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1331 debug("agent unlocked"); 1332 locked = 0; 1333 fail_count = 0; 1334 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1335 success = 1; 1336 } else { 1337 /* delay in 0.1s increments up to 10s */ 1338 if (fail_count < 100) 1339 fail_count++; 1340 delay = 100000 * fail_count; 1341 debug("unlock failed, delaying %0.1lf seconds", 1342 (double)delay/1000000); 1343 usleep(delay); 1344 } 1345 explicit_bzero(passwdhash, sizeof(passwdhash)); 1346 } else if (!locked && lock) { 1347 debug("agent locked"); 1348 locked = 1; 1349 arc4random_buf(lock_salt, sizeof(lock_salt)); 1350 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1351 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1352 fatal("bcrypt_pbkdf"); 1353 success = 1; 1354 } 1355 freezero(passwd, pwlen); 1356 send_status(e, success); 1357 } 1358 1359 static void 1360 no_identities(SocketEntry *e) 1361 { 1362 struct sshbuf *msg; 1363 int r; 1364 1365 if ((msg = sshbuf_new()) == NULL) 1366 fatal_f("sshbuf_new failed"); 1367 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1368 (r = sshbuf_put_u32(msg, 0)) != 0 || 1369 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1370 fatal_fr(r, "compose"); 1371 sshbuf_free(msg); 1372 } 1373 1374 #ifdef ENABLE_PKCS11 1375 static void 1376 process_add_smartcard_key(SocketEntry *e) 1377 { 1378 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1379 char **comments = NULL; 1380 int r, i, count = 0, success = 0, confirm = 0; 1381 u_int seconds = 0; 1382 time_t death = 0; 1383 struct sshkey **keys = NULL, *k; 1384 Identity *id; 1385 struct dest_constraint *dest_constraints = NULL; 1386 size_t ndest_constraints = 0; 1387 1388 debug2_f("entering"); 1389 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1390 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1391 error_fr(r, "parse"); 1392 goto send; 1393 } 1394 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1395 NULL, &dest_constraints, &ndest_constraints) != 0) { 1396 error_f("failed to parse constraints"); 1397 goto send; 1398 } 1399 if (e->nsession_ids != 0 && !remote_add_provider) { 1400 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1401 "providers is disabled", provider); 1402 goto send; 1403 } 1404 if (realpath(provider, canonical_provider) == NULL) { 1405 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1406 provider, strerror(errno)); 1407 goto send; 1408 } 1409 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1410 verbose("refusing PKCS#11 add of \"%.100s\": " 1411 "provider not allowed", canonical_provider); 1412 goto send; 1413 } 1414 debug_f("add %.100s", canonical_provider); 1415 if (lifetime && !death) 1416 death = monotime() + lifetime; 1417 1418 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1419 for (i = 0; i < count; i++) { 1420 k = keys[i]; 1421 if (lookup_identity(k) == NULL) { 1422 id = xcalloc(1, sizeof(Identity)); 1423 id->key = k; 1424 keys[i] = NULL; /* transferred */ 1425 id->provider = xstrdup(canonical_provider); 1426 if (*comments[i] != '\0') { 1427 id->comment = comments[i]; 1428 comments[i] = NULL; /* transferred */ 1429 } else { 1430 id->comment = xstrdup(canonical_provider); 1431 } 1432 id->death = death; 1433 id->confirm = confirm; 1434 id->dest_constraints = dest_constraints; 1435 id->ndest_constraints = ndest_constraints; 1436 dest_constraints = NULL; /* transferred */ 1437 ndest_constraints = 0; 1438 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1439 idtab->nentries++; 1440 success = 1; 1441 } 1442 /* XXX update constraints for existing keys */ 1443 sshkey_free(keys[i]); 1444 free(comments[i]); 1445 } 1446 send: 1447 free(pin); 1448 free(provider); 1449 free(keys); 1450 free(comments); 1451 free_dest_constraints(dest_constraints, ndest_constraints); 1452 send_status(e, success); 1453 } 1454 1455 static void 1456 process_remove_smartcard_key(SocketEntry *e) 1457 { 1458 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1459 int r, success = 0; 1460 Identity *id, *nxt; 1461 1462 debug2_f("entering"); 1463 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1464 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1465 error_fr(r, "parse"); 1466 goto send; 1467 } 1468 free(pin); 1469 1470 if (realpath(provider, canonical_provider) == NULL) { 1471 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1472 provider, strerror(errno)); 1473 goto send; 1474 } 1475 1476 debug_f("remove %.100s", canonical_provider); 1477 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1478 nxt = TAILQ_NEXT(id, next); 1479 /* Skip file--based keys */ 1480 if (id->provider == NULL) 1481 continue; 1482 if (!strcmp(canonical_provider, id->provider)) { 1483 TAILQ_REMOVE(&idtab->idlist, id, next); 1484 free_identity(id); 1485 idtab->nentries--; 1486 } 1487 } 1488 if (pkcs11_del_provider(canonical_provider) == 0) 1489 success = 1; 1490 else 1491 error_f("pkcs11_del_provider failed"); 1492 send: 1493 free(provider); 1494 send_status(e, success); 1495 } 1496 #endif /* ENABLE_PKCS11 */ 1497 1498 static int 1499 process_ext_session_bind(SocketEntry *e) 1500 { 1501 int r, sid_match, key_match; 1502 struct sshkey *key = NULL; 1503 struct sshbuf *sid = NULL, *sig = NULL; 1504 char *fp = NULL; 1505 size_t i; 1506 u_char fwd = 0; 1507 1508 debug2_f("entering"); 1509 if ((r = sshkey_froms(e->request, &key)) != 0 || 1510 (r = sshbuf_froms(e->request, &sid)) != 0 || 1511 (r = sshbuf_froms(e->request, &sig)) != 0 || 1512 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1513 error_fr(r, "parse"); 1514 goto out; 1515 } 1516 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1517 SSH_FP_DEFAULT)) == NULL) 1518 fatal_f("fingerprint failed"); 1519 /* check signature with hostkey on session ID */ 1520 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1521 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1522 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1523 goto out; 1524 } 1525 /* check whether sid/key already recorded */ 1526 for (i = 0; i < e->nsession_ids; i++) { 1527 if (!e->session_ids[i].forwarded) { 1528 error_f("attempt to bind session ID to socket " 1529 "previously bound for authentication attempt"); 1530 r = -1; 1531 goto out; 1532 } 1533 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1534 key_match = sshkey_equal(key, e->session_ids[i].key); 1535 if (sid_match && key_match) { 1536 debug_f("session ID already recorded for %s %s", 1537 sshkey_type(key), fp); 1538 r = 0; 1539 goto out; 1540 } else if (sid_match) { 1541 error_f("session ID recorded against different key " 1542 "for %s %s", sshkey_type(key), fp); 1543 r = -1; 1544 goto out; 1545 } 1546 /* 1547 * new sid with previously-seen key can happen, e.g. multiple 1548 * connections to the same host. 1549 */ 1550 } 1551 /* record new key/sid */ 1552 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1553 error_f("too many session IDs recorded"); 1554 goto out; 1555 } 1556 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1557 e->nsession_ids + 1, sizeof(*e->session_ids)); 1558 i = e->nsession_ids++; 1559 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1560 AGENT_MAX_SESSION_IDS); 1561 e->session_ids[i].key = key; 1562 e->session_ids[i].forwarded = fwd != 0; 1563 key = NULL; /* transferred */ 1564 /* can't transfer sid; it's refcounted and scoped to request's life */ 1565 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1566 fatal_f("sshbuf_new"); 1567 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1568 fatal_fr(r, "sshbuf_putb session ID"); 1569 /* success */ 1570 r = 0; 1571 out: 1572 free(fp); 1573 sshkey_free(key); 1574 sshbuf_free(sid); 1575 sshbuf_free(sig); 1576 return r == 0 ? 1 : 0; 1577 } 1578 1579 static void 1580 process_extension(SocketEntry *e) 1581 { 1582 int r, success = 0; 1583 char *name; 1584 1585 debug2_f("entering"); 1586 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1587 error_fr(r, "parse"); 1588 goto send; 1589 } 1590 if (strcmp(name, "session-bind@openssh.com") == 0) 1591 success = process_ext_session_bind(e); 1592 else 1593 debug_f("unsupported extension \"%s\"", name); 1594 free(name); 1595 send: 1596 send_status(e, success); 1597 } 1598 /* 1599 * dispatch incoming message. 1600 * returns 1 on success, 0 for incomplete messages or -1 on error. 1601 */ 1602 static int 1603 process_message(u_int socknum) 1604 { 1605 u_int msg_len; 1606 u_char type; 1607 const u_char *cp; 1608 int r; 1609 SocketEntry *e; 1610 1611 if (socknum >= sockets_alloc) 1612 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1613 e = &sockets[socknum]; 1614 1615 if (sshbuf_len(e->input) < 5) 1616 return 0; /* Incomplete message header. */ 1617 cp = sshbuf_ptr(e->input); 1618 msg_len = PEEK_U32(cp); 1619 if (msg_len > AGENT_MAX_LEN) { 1620 debug_f("socket %u (fd=%d) message too long %u > %u", 1621 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1622 return -1; 1623 } 1624 if (sshbuf_len(e->input) < msg_len + 4) 1625 return 0; /* Incomplete message body. */ 1626 1627 /* move the current input to e->request */ 1628 sshbuf_reset(e->request); 1629 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1630 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1631 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1632 r == SSH_ERR_STRING_TOO_LARGE) { 1633 error_fr(r, "parse"); 1634 return -1; 1635 } 1636 fatal_fr(r, "parse"); 1637 } 1638 1639 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1640 1641 /* check whether agent is locked */ 1642 if (locked && type != SSH_AGENTC_UNLOCK) { 1643 sshbuf_reset(e->request); 1644 switch (type) { 1645 case SSH2_AGENTC_REQUEST_IDENTITIES: 1646 /* send empty lists */ 1647 no_identities(e); 1648 break; 1649 default: 1650 /* send a fail message for all other request types */ 1651 send_status(e, 0); 1652 } 1653 return 1; 1654 } 1655 1656 switch (type) { 1657 case SSH_AGENTC_LOCK: 1658 case SSH_AGENTC_UNLOCK: 1659 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1660 break; 1661 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1662 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1663 break; 1664 /* ssh2 */ 1665 case SSH2_AGENTC_SIGN_REQUEST: 1666 process_sign_request2(e); 1667 break; 1668 case SSH2_AGENTC_REQUEST_IDENTITIES: 1669 process_request_identities(e); 1670 break; 1671 case SSH2_AGENTC_ADD_IDENTITY: 1672 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1673 process_add_identity(e); 1674 break; 1675 case SSH2_AGENTC_REMOVE_IDENTITY: 1676 process_remove_identity(e); 1677 break; 1678 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1679 process_remove_all_identities(e); 1680 break; 1681 #ifdef ENABLE_PKCS11 1682 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1683 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1684 process_add_smartcard_key(e); 1685 break; 1686 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1687 process_remove_smartcard_key(e); 1688 break; 1689 #endif /* ENABLE_PKCS11 */ 1690 case SSH_AGENTC_EXTENSION: 1691 process_extension(e); 1692 break; 1693 default: 1694 /* Unknown message. Respond with failure. */ 1695 error("Unknown message %d", type); 1696 sshbuf_reset(e->request); 1697 send_status(e, 0); 1698 break; 1699 } 1700 return 1; 1701 } 1702 1703 static void 1704 new_socket(sock_type type, int fd) 1705 { 1706 u_int i, old_alloc, new_alloc; 1707 1708 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1709 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1710 set_nonblock(fd); 1711 1712 if (fd > max_fd) 1713 max_fd = fd; 1714 1715 for (i = 0; i < sockets_alloc; i++) 1716 if (sockets[i].type == AUTH_UNUSED) { 1717 sockets[i].fd = fd; 1718 if ((sockets[i].input = sshbuf_new()) == NULL || 1719 (sockets[i].output = sshbuf_new()) == NULL || 1720 (sockets[i].request = sshbuf_new()) == NULL) 1721 fatal_f("sshbuf_new failed"); 1722 sockets[i].type = type; 1723 return; 1724 } 1725 old_alloc = sockets_alloc; 1726 new_alloc = sockets_alloc + 10; 1727 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1728 sizeof(sockets[0])); 1729 for (i = old_alloc; i < new_alloc; i++) 1730 sockets[i].type = AUTH_UNUSED; 1731 sockets_alloc = new_alloc; 1732 sockets[old_alloc].fd = fd; 1733 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1734 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1735 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1736 fatal_f("sshbuf_new failed"); 1737 sockets[old_alloc].type = type; 1738 } 1739 1740 static int 1741 handle_socket_read(u_int socknum) 1742 { 1743 struct sockaddr_un sunaddr; 1744 socklen_t slen; 1745 uid_t euid; 1746 gid_t egid; 1747 int fd; 1748 1749 slen = sizeof(sunaddr); 1750 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1751 if (fd == -1) { 1752 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1753 return -1; 1754 } 1755 if (getpeereid(fd, &euid, &egid) == -1) { 1756 error("getpeereid %d failed: %s", fd, strerror(errno)); 1757 close(fd); 1758 return -1; 1759 } 1760 if ((euid != 0) && (getuid() != euid)) { 1761 error("uid mismatch: peer euid %u != uid %u", 1762 (u_int) euid, (u_int) getuid()); 1763 close(fd); 1764 return -1; 1765 } 1766 new_socket(AUTH_CONNECTION, fd); 1767 return 0; 1768 } 1769 1770 static int 1771 handle_conn_read(u_int socknum) 1772 { 1773 char buf[AGENT_RBUF_LEN]; 1774 ssize_t len; 1775 int r; 1776 1777 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1778 if (len == -1) { 1779 if (errno == EAGAIN || errno == EINTR) 1780 return 0; 1781 error_f("read error on socket %u (fd %d): %s", 1782 socknum, sockets[socknum].fd, strerror(errno)); 1783 } 1784 return -1; 1785 } 1786 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1787 fatal_fr(r, "compose"); 1788 explicit_bzero(buf, sizeof(buf)); 1789 for (;;) { 1790 if ((r = process_message(socknum)) == -1) 1791 return -1; 1792 else if (r == 0) 1793 break; 1794 } 1795 return 0; 1796 } 1797 1798 static int 1799 handle_conn_write(u_int socknum) 1800 { 1801 ssize_t len; 1802 int r; 1803 1804 if (sshbuf_len(sockets[socknum].output) == 0) 1805 return 0; /* shouldn't happen */ 1806 if ((len = write(sockets[socknum].fd, 1807 sshbuf_ptr(sockets[socknum].output), 1808 sshbuf_len(sockets[socknum].output))) <= 0) { 1809 if (len == -1) { 1810 if (errno == EAGAIN || errno == EINTR) 1811 return 0; 1812 error_f("read error on socket %u (fd %d): %s", 1813 socknum, sockets[socknum].fd, strerror(errno)); 1814 } 1815 return -1; 1816 } 1817 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1818 fatal_fr(r, "consume"); 1819 return 0; 1820 } 1821 1822 static void 1823 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1824 { 1825 size_t i; 1826 u_int socknum, activefds = npfd; 1827 1828 for (i = 0; i < npfd; i++) { 1829 if (pfd[i].revents == 0) 1830 continue; 1831 /* Find sockets entry */ 1832 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1833 if (sockets[socknum].type != AUTH_SOCKET && 1834 sockets[socknum].type != AUTH_CONNECTION) 1835 continue; 1836 if (pfd[i].fd == sockets[socknum].fd) 1837 break; 1838 } 1839 if (socknum >= sockets_alloc) { 1840 error_f("no socket for fd %d", pfd[i].fd); 1841 continue; 1842 } 1843 /* Process events */ 1844 switch (sockets[socknum].type) { 1845 case AUTH_SOCKET: 1846 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1847 break; 1848 if (npfd > maxfds) { 1849 debug3("out of fds (active %u >= limit %u); " 1850 "skipping accept", activefds, maxfds); 1851 break; 1852 } 1853 if (handle_socket_read(socknum) == 0) 1854 activefds++; 1855 break; 1856 case AUTH_CONNECTION: 1857 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1858 handle_conn_read(socknum) != 0) 1859 goto close_sock; 1860 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1861 handle_conn_write(socknum) != 0) { 1862 close_sock: 1863 if (activefds == 0) 1864 fatal("activefds == 0 at close_sock"); 1865 close_socket(&sockets[socknum]); 1866 activefds--; 1867 break; 1868 } 1869 break; 1870 default: 1871 break; 1872 } 1873 } 1874 } 1875 1876 static int 1877 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1878 { 1879 struct pollfd *pfd = *pfdp; 1880 size_t i, j, npfd = 0; 1881 time_t deadline; 1882 int r; 1883 1884 /* Count active sockets */ 1885 for (i = 0; i < sockets_alloc; i++) { 1886 switch (sockets[i].type) { 1887 case AUTH_SOCKET: 1888 case AUTH_CONNECTION: 1889 npfd++; 1890 break; 1891 case AUTH_UNUSED: 1892 break; 1893 default: 1894 fatal("Unknown socket type %d", sockets[i].type); 1895 break; 1896 } 1897 } 1898 if (npfd != *npfdp && 1899 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1900 fatal_f("recallocarray failed"); 1901 *pfdp = pfd; 1902 *npfdp = npfd; 1903 1904 for (i = j = 0; i < sockets_alloc; i++) { 1905 switch (sockets[i].type) { 1906 case AUTH_SOCKET: 1907 if (npfd > maxfds) { 1908 debug3("out of fds (active %zu >= limit %u); " 1909 "skipping arming listener", npfd, maxfds); 1910 break; 1911 } 1912 pfd[j].fd = sockets[i].fd; 1913 pfd[j].revents = 0; 1914 pfd[j].events = POLLIN; 1915 j++; 1916 break; 1917 case AUTH_CONNECTION: 1918 pfd[j].fd = sockets[i].fd; 1919 pfd[j].revents = 0; 1920 /* 1921 * Only prepare to read if we can handle a full-size 1922 * input read buffer and enqueue a max size reply.. 1923 */ 1924 if ((r = sshbuf_check_reserve(sockets[i].input, 1925 AGENT_RBUF_LEN)) == 0 && 1926 (r = sshbuf_check_reserve(sockets[i].output, 1927 AGENT_MAX_LEN)) == 0) 1928 pfd[j].events = POLLIN; 1929 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1930 fatal_fr(r, "reserve"); 1931 if (sshbuf_len(sockets[i].output) > 0) 1932 pfd[j].events |= POLLOUT; 1933 j++; 1934 break; 1935 default: 1936 break; 1937 } 1938 } 1939 deadline = reaper(); 1940 if (parent_alive_interval != 0) 1941 deadline = (deadline == 0) ? parent_alive_interval : 1942 MINIMUM(deadline, parent_alive_interval); 1943 if (deadline == 0) { 1944 *timeoutp = -1; /* INFTIM */ 1945 } else { 1946 if (deadline > INT_MAX / 1000) 1947 *timeoutp = INT_MAX / 1000; 1948 else 1949 *timeoutp = deadline * 1000; 1950 } 1951 return (1); 1952 } 1953 1954 static void 1955 cleanup_socket(void) 1956 { 1957 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1958 return; 1959 debug_f("cleanup"); 1960 if (socket_name[0]) 1961 unlink(socket_name); 1962 if (socket_dir[0]) 1963 rmdir(socket_dir); 1964 } 1965 1966 void 1967 cleanup_exit(int i) 1968 { 1969 cleanup_socket(); 1970 _exit(i); 1971 } 1972 1973 /*ARGSUSED*/ 1974 __dead static void 1975 cleanup_handler(int sig) 1976 { 1977 cleanup_socket(); 1978 #ifdef ENABLE_PKCS11 1979 pkcs11_terminate(); 1980 #endif 1981 _exit(2); 1982 } 1983 1984 static void 1985 check_parent_exists(void) 1986 { 1987 /* 1988 * If our parent has exited then getppid() will return (pid_t)1, 1989 * so testing for that should be safe. 1990 */ 1991 if (parent_pid != -1 && getppid() != parent_pid) { 1992 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1993 cleanup_socket(); 1994 _exit(2); 1995 } 1996 } 1997 1998 __dead static void 1999 usage(void) 2000 { 2001 fprintf(stderr, 2002 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 2003 " [-O option] [-P allowed_providers] [-t life]\n" 2004 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2005 " [-P allowed_providers] [-t life] command [arg ...]\n" 2006 " ssh-agent [-c | -s] -k\n"); 2007 exit(1); 2008 } 2009 2010 static void 2011 csh_setenv(const char *name, const char *value) 2012 { 2013 printf("setenv %s %s;\n", name, value); 2014 } 2015 2016 static void 2017 csh_unsetenv(const char *name) 2018 { 2019 printf("unsetenv %s;\n", name); 2020 } 2021 2022 static void 2023 sh_setenv(const char *name, const char *value) 2024 { 2025 printf("%s=%s; export %s;\n", name, value, name); 2026 } 2027 2028 static void 2029 sh_unsetenv(const char *name) 2030 { 2031 printf("unset %s;\n", name); 2032 } 2033 int 2034 main(int ac, char **av) 2035 { 2036 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2037 int sock, ch, result, saved_errno; 2038 char *shell, *pidstr, *agentsocket = NULL; 2039 struct rlimit rlim; 2040 void (*f_setenv)(const char *, const char *); 2041 void (*f_unsetenv)(const char *); 2042 extern int optind; 2043 extern char *optarg; 2044 pid_t pid; 2045 char pidstrbuf[1 + 3 * sizeof pid]; 2046 size_t len; 2047 mode_t prev_mask; 2048 int timeout = -1; /* INFTIM */ 2049 struct pollfd *pfd = NULL; 2050 size_t npfd = 0; 2051 u_int maxfds; 2052 2053 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2054 sanitise_stdfd(); 2055 2056 /* drop */ 2057 setegid(getgid()); 2058 setgid(getgid()); 2059 2060 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2061 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2062 2063 #ifdef WITH_OPENSSL 2064 OpenSSL_add_all_algorithms(); 2065 #endif 2066 2067 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2068 switch (ch) { 2069 case 'E': 2070 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2071 if (fingerprint_hash == -1) 2072 fatal("Invalid hash algorithm \"%s\"", optarg); 2073 break; 2074 case 'c': 2075 if (s_flag) 2076 usage(); 2077 c_flag++; 2078 break; 2079 case 'k': 2080 k_flag++; 2081 break; 2082 case 'O': 2083 if (strcmp(optarg, "no-restrict-websafe") == 0) 2084 restrict_websafe = 0; 2085 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2086 remote_add_provider = 1; 2087 else 2088 fatal("Unknown -O option"); 2089 break; 2090 case 'P': 2091 if (allowed_providers != NULL) 2092 fatal("-P option already specified"); 2093 allowed_providers = xstrdup(optarg); 2094 break; 2095 case 's': 2096 if (c_flag) 2097 usage(); 2098 s_flag++; 2099 break; 2100 case 'd': 2101 if (d_flag || D_flag) 2102 usage(); 2103 d_flag++; 2104 break; 2105 case 'D': 2106 if (d_flag || D_flag) 2107 usage(); 2108 D_flag++; 2109 break; 2110 case 'a': 2111 agentsocket = optarg; 2112 break; 2113 case 't': 2114 if ((lifetime = convtime(optarg)) == -1) { 2115 fprintf(stderr, "Invalid lifetime\n"); 2116 usage(); 2117 } 2118 break; 2119 default: 2120 usage(); 2121 } 2122 } 2123 ac -= optind; 2124 av += optind; 2125 2126 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2127 usage(); 2128 2129 if (allowed_providers == NULL) 2130 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2131 2132 if (ac == 0 && !c_flag && !s_flag) { 2133 shell = getenv("SHELL"); 2134 if (shell != NULL && (len = strlen(shell)) > 2 && 2135 strncmp(shell + len - 3, "csh", 3) == 0) 2136 c_flag = 1; 2137 } 2138 if (c_flag) { 2139 f_setenv = csh_setenv; 2140 f_unsetenv = csh_unsetenv; 2141 } else { 2142 f_setenv = sh_setenv; 2143 f_unsetenv = sh_unsetenv; 2144 } 2145 if (k_flag) { 2146 const char *errstr = NULL; 2147 2148 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2149 if (pidstr == NULL) { 2150 fprintf(stderr, "%s not set, cannot kill agent\n", 2151 SSH_AGENTPID_ENV_NAME); 2152 exit(1); 2153 } 2154 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2155 if (errstr) { 2156 fprintf(stderr, 2157 "%s=\"%s\", which is not a good PID: %s\n", 2158 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2159 exit(1); 2160 } 2161 if (kill(pid, SIGTERM) == -1) { 2162 perror("kill"); 2163 exit(1); 2164 } 2165 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 2166 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 2167 printf("echo Agent pid %ld killed;\n", (long)pid); 2168 exit(0); 2169 } 2170 2171 /* 2172 * Minimum file descriptors: 2173 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2174 * a few spare for libc / stack protectors / sanitisers, etc. 2175 */ 2176 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2177 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2178 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2179 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2180 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2181 2182 parent_pid = getpid(); 2183 2184 if (agentsocket == NULL) { 2185 /* Create private directory for agent socket */ 2186 mktemp_proto(socket_dir, sizeof(socket_dir)); 2187 if (mkdtemp(socket_dir) == NULL) { 2188 perror("mkdtemp: private socket dir"); 2189 exit(1); 2190 } 2191 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2192 (long)parent_pid); 2193 } else { 2194 /* Try to use specified agent socket */ 2195 socket_dir[0] = '\0'; 2196 strlcpy(socket_name, agentsocket, sizeof socket_name); 2197 } 2198 2199 /* 2200 * Create socket early so it will exist before command gets run from 2201 * the parent. 2202 */ 2203 prev_mask = umask(0177); 2204 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2205 if (sock < 0) { 2206 /* XXX - unix_listener() calls error() not perror() */ 2207 *socket_name = '\0'; /* Don't unlink any existing file */ 2208 cleanup_exit(1); 2209 } 2210 umask(prev_mask); 2211 2212 /* 2213 * Fork, and have the parent execute the command, if any, or present 2214 * the socket data. The child continues as the authentication agent. 2215 */ 2216 if (D_flag || d_flag) { 2217 log_init(__progname, 2218 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2219 SYSLOG_FACILITY_AUTH, 1); 2220 if (c_flag) 2221 printf("setenv %s %s;\n", 2222 SSH_AUTHSOCKET_ENV_NAME, socket_name); 2223 else 2224 printf("%s=%s; export %s;\n", 2225 SSH_AUTHSOCKET_ENV_NAME, socket_name, 2226 SSH_AUTHSOCKET_ENV_NAME); 2227 printf("echo Agent pid %ld;\n", (long)parent_pid); 2228 fflush(stdout); 2229 goto skip; 2230 } 2231 pid = fork(); 2232 if (pid == -1) { 2233 perror("fork"); 2234 cleanup_exit(1); 2235 } 2236 if (pid != 0) { /* Parent - execute the given command. */ 2237 close(sock); 2238 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2239 if (ac == 0) { 2240 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 2241 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 2242 printf("echo Agent pid %ld;\n", (long)pid); 2243 exit(0); 2244 } 2245 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2246 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2247 perror("setenv"); 2248 exit(1); 2249 } 2250 execvp(av[0], av); 2251 perror(av[0]); 2252 exit(1); 2253 } 2254 /* child */ 2255 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2256 2257 if (setsid() == -1) { 2258 error("setsid: %s", strerror(errno)); 2259 cleanup_exit(1); 2260 } 2261 2262 (void)chdir("/"); 2263 if (stdfd_devnull(1, 1, 1) == -1) 2264 error_f("stdfd_devnull failed"); 2265 2266 /* deny core dumps, since memory contains unencrypted private keys */ 2267 rlim.rlim_cur = rlim.rlim_max = 0; 2268 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2269 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2270 cleanup_exit(1); 2271 } 2272 2273 skip: 2274 2275 cleanup_pid = getpid(); 2276 2277 #ifdef ENABLE_PKCS11 2278 pkcs11_init(0); 2279 #endif 2280 new_socket(AUTH_SOCKET, sock); 2281 if (ac > 0) 2282 parent_alive_interval = 10; 2283 idtab_init(); 2284 ssh_signal(SIGPIPE, SIG_IGN); 2285 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2286 ssh_signal(SIGHUP, cleanup_handler); 2287 ssh_signal(SIGTERM, cleanup_handler); 2288 2289 #ifdef __OpenBSD__ 2290 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2291 fatal("%s: pledge: %s", __progname, strerror(errno)); 2292 #endif 2293 2294 while (1) { 2295 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2296 result = poll(pfd, npfd, timeout); 2297 saved_errno = errno; 2298 if (parent_alive_interval != 0) 2299 check_parent_exists(); 2300 (void) reaper(); /* remove expired keys */ 2301 if (result == -1) { 2302 if (saved_errno == EINTR) 2303 continue; 2304 fatal("poll: %s", strerror(saved_errno)); 2305 } else if (result > 0) 2306 after_poll(pfd, npfd, maxfds); 2307 } 2308 /* NOTREACHED */ 2309 } 2310