1 /* $NetBSD: ssh-agent.c,v 1.33 2022/02/23 19:07:20 christos Exp $ */ 2 /* $OpenBSD: ssh-agent.c,v 1.287 2022/01/14 03:43:48 djm 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 1.33 2022/02/23 19:07:20 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 "compat.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 "ssherr.h" 84 #include "pathnames.h" 85 #include "ssh-pkcs11.h" 86 #include "sk-api.h" 87 #include "myproposal.h" 88 89 #ifndef DEFAULT_ALLOWED_PROVIDERS 90 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/pkg/lib*/*" 91 #endif 92 93 /* Maximum accepted message length */ 94 #define AGENT_MAX_LEN (256*1024) 95 /* Maximum bytes to read from client socket */ 96 #define AGENT_RBUF_LEN (4096) 97 /* Maximum number of recorded session IDs/hostkeys per connection */ 98 #define AGENT_MAX_SESSION_IDS 16 99 /* Maximum size of session ID */ 100 #define AGENT_MAX_SID_LEN 128 101 /* Maximum number of destination constraints to accept on a key */ 102 #define AGENT_MAX_DEST_CONSTRAINTS 1024 103 104 /* XXX store hostkey_sid in a refcounted tree */ 105 106 typedef enum { 107 AUTH_UNUSED = 0, 108 AUTH_SOCKET = 1, 109 AUTH_CONNECTION = 2, 110 } sock_type; 111 112 struct hostkey_sid { 113 struct sshkey *key; 114 struct sshbuf *sid; 115 int forwarded; 116 }; 117 118 typedef struct socket_entry { 119 int fd; 120 sock_type type; 121 struct sshbuf *input; 122 struct sshbuf *output; 123 struct sshbuf *request; 124 size_t nsession_ids; 125 struct hostkey_sid *session_ids; 126 } SocketEntry; 127 128 u_int sockets_alloc = 0; 129 SocketEntry *sockets = NULL; 130 131 typedef struct identity { 132 TAILQ_ENTRY(identity) next; 133 struct sshkey *key; 134 char *comment; 135 char *provider; 136 time_t death; 137 u_int confirm; 138 char *sk_provider; 139 struct dest_constraint *dest_constraints; 140 size_t ndest_constraints; 141 } Identity; 142 143 struct idtable { 144 int nentries; 145 TAILQ_HEAD(idqueue, identity) idlist; 146 }; 147 148 /* private key table */ 149 struct idtable *idtab; 150 151 int max_fd = 0; 152 153 /* pid of shell == parent of agent */ 154 pid_t parent_pid = -1; 155 time_t parent_alive_interval = 0; 156 157 /* pid of process for which cleanup_socket is applicable */ 158 pid_t cleanup_pid = 0; 159 160 /* pathname and directory for AUTH_SOCKET */ 161 char socket_name[PATH_MAX]; 162 char socket_dir[PATH_MAX]; 163 164 /* Pattern-list of allowed PKCS#11/Security key paths */ 165 static char *allowed_providers; 166 167 /* locking */ 168 #define LOCK_SIZE 32 169 #define LOCK_SALT_SIZE 16 170 #define LOCK_ROUNDS 1 171 int locked = 0; 172 u_char lock_pwhash[LOCK_SIZE]; 173 u_char lock_salt[LOCK_SALT_SIZE]; 174 175 extern char *__progname; 176 177 /* Default lifetime in seconds (0 == forever) */ 178 static int lifetime = 0; 179 180 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 181 182 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 183 static int restrict_websafe = 1; 184 185 static void 186 close_socket(SocketEntry *e) 187 { 188 size_t i; 189 190 close(e->fd); 191 sshbuf_free(e->input); 192 sshbuf_free(e->output); 193 sshbuf_free(e->request); 194 for (i = 0; i < e->nsession_ids; i++) { 195 sshkey_free(e->session_ids[i].key); 196 sshbuf_free(e->session_ids[i].sid); 197 } 198 free(e->session_ids); 199 memset(e, '\0', sizeof(*e)); 200 e->fd = -1; 201 e->type = AUTH_UNUSED; 202 } 203 204 static void 205 idtab_init(void) 206 { 207 idtab = xcalloc(1, sizeof(*idtab)); 208 TAILQ_INIT(&idtab->idlist); 209 idtab->nentries = 0; 210 } 211 212 static void 213 free_dest_constraint_hop(struct dest_constraint_hop *dch) 214 { 215 u_int i; 216 217 if (dch == NULL) 218 return; 219 free(dch->user); 220 free(dch->hostname); 221 for (i = 0; i < dch->nkeys; i++) 222 sshkey_free(dch->keys[i]); 223 free(dch->keys); 224 free(dch->key_is_ca); 225 } 226 227 static void 228 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 229 { 230 size_t i; 231 232 for (i = 0; i < ndcs; i++) { 233 free_dest_constraint_hop(&dcs[i].from); 234 free_dest_constraint_hop(&dcs[i].to); 235 } 236 free(dcs); 237 } 238 239 static void 240 free_identity(Identity *id) 241 { 242 sshkey_free(id->key); 243 free(id->provider); 244 free(id->comment); 245 free(id->sk_provider); 246 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 247 free(id); 248 } 249 250 /* 251 * Match 'key' against the key/CA list in a destination constraint hop 252 * Returns 0 on success or -1 otherwise. 253 */ 254 static int 255 match_key_hop(const char *tag, const struct sshkey *key, 256 const struct dest_constraint_hop *dch) 257 { 258 const char *reason = NULL; 259 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 260 u_int i; 261 char *fp; 262 263 if (key == NULL) 264 return -1; 265 /* XXX logspam */ 266 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 267 SSH_FP_DEFAULT)) == NULL) 268 fatal_f("fingerprint failed"); 269 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 270 tag, hostname, sshkey_type(key), fp, dch->nkeys); 271 free(fp); 272 for (i = 0; i < dch->nkeys; i++) { 273 if (dch->keys[i] == NULL) 274 return -1; 275 /* XXX logspam */ 276 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 277 SSH_FP_DEFAULT)) == NULL) 278 fatal_f("fingerprint failed"); 279 debug3_f("%s: key %u: %s%s %s", tag, i, 280 dch->key_is_ca[i] ? "CA " : "", 281 sshkey_type(dch->keys[i]), fp); 282 free(fp); 283 if (!sshkey_is_cert(key)) { 284 /* plain key */ 285 if (dch->key_is_ca[i] || 286 !sshkey_equal(key, dch->keys[i])) 287 continue; 288 return 0; 289 } 290 /* certificate */ 291 if (!dch->key_is_ca[i]) 292 continue; 293 if (key->cert == NULL || key->cert->signature_key == NULL) 294 return -1; /* shouldn't happen */ 295 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 296 continue; 297 if (sshkey_cert_check_host(key, hostname, 1, 298 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 299 debug_f("cert %s / hostname %s rejected: %s", 300 key->cert->key_id, hostname, reason); 301 continue; 302 } 303 return 0; 304 } 305 return -1; 306 } 307 308 /* Check destination constraints on an identity against the hostkey/user */ 309 static int 310 permitted_by_dest_constraints(const struct sshkey *fromkey, 311 const struct sshkey *tokey, Identity *id, const char *user, 312 const char **hostnamep) 313 { 314 size_t i; 315 struct dest_constraint *d; 316 317 if (hostnamep != NULL) 318 *hostnamep = NULL; 319 for (i = 0; i < id->ndest_constraints; i++) { 320 d = id->dest_constraints + i; 321 /* XXX remove logspam */ 322 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 323 i, d->from.user ? d->from.user : "", 324 d->from.user ? "@" : "", 325 d->from.hostname ? d->from.hostname : "(ORIGIN)", 326 d->from.nkeys, 327 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 328 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 329 330 /* Match 'from' key */ 331 if (fromkey == NULL) { 332 /* We are matching the first hop */ 333 if (d->from.hostname != NULL || d->from.nkeys != 0) 334 continue; 335 } else if (match_key_hop("from", fromkey, &d->from) != 0) 336 continue; 337 338 /* Match 'to' key */ 339 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 340 continue; 341 342 /* Match user if specified */ 343 if (d->to.user != NULL && user != NULL && 344 !match_pattern(user, d->to.user)) 345 continue; 346 347 /* successfully matched this constraint */ 348 if (hostnamep != NULL) 349 *hostnamep = d->to.hostname; 350 debug2_f("allowed for hostname %s", 351 d->to.hostname == NULL ? "*" : d->to.hostname); 352 return 0; 353 } 354 /* no match */ 355 debug2_f("%s identity \"%s\" not permitted for this destination", 356 sshkey_type(id->key), id->comment); 357 return -1; 358 } 359 360 /* 361 * Check whether hostkeys on a SocketEntry and the optionally specified user 362 * are permitted by the destination constraints on the Identity. 363 * Returns 0 on success or -1 otherwise. 364 */ 365 static int 366 identity_permitted(Identity *id, SocketEntry *e, char *user, 367 const char **forward_hostnamep, const char **last_hostnamep) 368 { 369 size_t i; 370 const char **hp; 371 struct hostkey_sid *hks; 372 const struct sshkey *fromkey = NULL; 373 const char *test_user; 374 char *fp1, *fp2; 375 376 /* XXX remove logspam */ 377 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 378 "%zu constraints", sshkey_type(id->key), id->comment, 379 e->nsession_ids, id->ndest_constraints); 380 if (id->ndest_constraints == 0) 381 return 0; /* unconstrained */ 382 if (e->nsession_ids == 0) 383 return 0; /* local use */ 384 /* 385 * Walk through the hops recorded by session_id and try to find a 386 * constraint that satisfies each. 387 */ 388 for (i = 0; i < e->nsession_ids; i++) { 389 hks = e->session_ids + i; 390 if (hks->key == NULL) 391 fatal_f("internal error: no bound key"); 392 /* XXX remove logspam */ 393 fp1 = fp2 = NULL; 394 if (fromkey != NULL && 395 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 396 SSH_FP_DEFAULT)) == NULL) 397 fatal_f("fingerprint failed"); 398 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 399 SSH_FP_DEFAULT)) == NULL) 400 fatal_f("fingerprint failed"); 401 debug3_f("socketentry fd=%d, entry %zu %s, " 402 "from hostkey %s %s to user %s hostkey %s %s", 403 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 404 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 405 fromkey ? fp1 : "", user ? user : "(ANY)", 406 sshkey_type(hks->key), fp2); 407 free(fp1); 408 free(fp2); 409 /* 410 * Record the hostnames for the initial forwarding and 411 * the final destination. 412 */ 413 hp = NULL; 414 if (i == e->nsession_ids - 1) 415 hp = last_hostnamep; 416 else if (i == 0) 417 hp = forward_hostnamep; 418 /* Special handling for final recorded binding */ 419 test_user = NULL; 420 if (i == e->nsession_ids - 1) { 421 /* Can only check user at final hop */ 422 test_user = user; 423 /* 424 * user is only presented for signature requests. 425 * If this is the case, make sure last binding is not 426 * for a forwarding. 427 */ 428 if (hks->forwarded && user != NULL) { 429 error_f("tried to sign on forwarding hop"); 430 return -1; 431 } 432 } else if (!hks->forwarded) { 433 error_f("tried to forward though signing bind"); 434 return -1; 435 } 436 if (permitted_by_dest_constraints(fromkey, hks->key, id, 437 test_user, hp) != 0) 438 return -1; 439 fromkey = hks->key; 440 } 441 /* 442 * Another special case: if the last bound session ID was for a 443 * forwarding, and this function is not being called to check a sign 444 * request (i.e. no 'user' supplied), then only permit the key if 445 * there is a permission that would allow it to be used at another 446 * destination. This hides keys that are allowed to be used to 447 * authenticate *to* a host but not permitted for *use* beyond it. 448 */ 449 hks = &e->session_ids[e->nsession_ids - 1]; 450 if (hks->forwarded && user == NULL && 451 permitted_by_dest_constraints(hks->key, NULL, id, 452 NULL, NULL) != 0) { 453 debug3_f("key permitted at host but not after"); 454 return -1; 455 } 456 457 /* success */ 458 return 0; 459 } 460 461 /* return matching private key for given public key */ 462 static Identity * 463 lookup_identity(struct sshkey *key) 464 { 465 Identity *id; 466 467 TAILQ_FOREACH(id, &idtab->idlist, next) { 468 if (sshkey_equal(key, id->key)) 469 return (id); 470 } 471 return (NULL); 472 } 473 474 /* Check confirmation of keysign request */ 475 static int 476 confirm_key(Identity *id, const char *extra) 477 { 478 char *p; 479 int ret = -1; 480 481 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 482 if (p != NULL && 483 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 484 id->comment, p, 485 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 486 ret = 0; 487 free(p); 488 489 return (ret); 490 } 491 492 static void 493 send_status(SocketEntry *e, int success) 494 { 495 int r; 496 497 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 498 (r = sshbuf_put_u8(e->output, success ? 499 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 500 fatal_fr(r, "compose"); 501 } 502 503 /* send list of supported public keys to 'client' */ 504 static void 505 process_request_identities(SocketEntry *e) 506 { 507 Identity *id; 508 struct sshbuf *msg, *keys; 509 int r; 510 u_int nentries = 0; 511 512 debug2_f("entering"); 513 514 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 515 fatal_f("sshbuf_new failed"); 516 TAILQ_FOREACH(id, &idtab->idlist, next) { 517 /* identity not visible, don't include in response */ 518 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 519 continue; 520 if ((r = sshkey_puts_opts(id->key, keys, 521 SSHKEY_SERIALIZE_INFO)) != 0 || 522 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 523 error_fr(r, "compose key/comment"); 524 continue; 525 } 526 nentries++; 527 } 528 debug2_f("replying with %u allowed of %u available keys", 529 nentries, idtab->nentries); 530 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 531 (r = sshbuf_put_u32(msg, nentries)) != 0 || 532 (r = sshbuf_putb(msg, keys)) != 0) 533 fatal_fr(r, "compose"); 534 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 535 fatal_fr(r, "enqueue"); 536 sshbuf_free(msg); 537 sshbuf_free(keys); 538 } 539 540 541 static const char * 542 agent_decode_alg(struct sshkey *key, u_int flags) 543 { 544 if (key->type == KEY_RSA) { 545 if (flags & SSH_AGENT_RSA_SHA2_256) 546 return "rsa-sha2-256"; 547 else if (flags & SSH_AGENT_RSA_SHA2_512) 548 return "rsa-sha2-512"; 549 } else if (key->type == KEY_RSA_CERT) { 550 if (flags & SSH_AGENT_RSA_SHA2_256) 551 return "rsa-sha2-256-cert-v01@openssh.com"; 552 else if (flags & SSH_AGENT_RSA_SHA2_512) 553 return "rsa-sha2-512-cert-v01@openssh.com"; 554 } 555 return NULL; 556 } 557 558 /* 559 * Attempt to parse the contents of a buffer as a SSH publickey userauth 560 * request, checking its contents for consistency and matching the embedded 561 * key against the one that is being used for signing. 562 * Note: does not modify msg buffer. 563 * Optionally extract the username, session ID and/or hostkey from the request. 564 */ 565 static int 566 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 567 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 568 { 569 struct sshbuf *b = NULL, *sess_id = NULL; 570 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 571 int r; 572 u_char t, sig_follows; 573 struct sshkey *mkey = NULL, *hostkey = NULL; 574 575 if (userp != NULL) 576 *userp = NULL; 577 if (sess_idp != NULL) 578 *sess_idp = NULL; 579 if (hostkeyp != NULL) 580 *hostkeyp = NULL; 581 if ((b = sshbuf_fromb(msg)) == NULL) 582 fatal_f("sshbuf_fromb"); 583 584 /* SSH userauth request */ 585 if ((r = sshbuf_froms(b, &sess_id)) != 0) 586 goto out; 587 if (sshbuf_len(sess_id) == 0) { 588 r = SSH_ERR_INVALID_FORMAT; 589 goto out; 590 } 591 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 592 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 593 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 594 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 595 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 596 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 597 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 598 goto out; 599 if (t != SSH2_MSG_USERAUTH_REQUEST || 600 sig_follows != 1 || 601 strcmp(service, "ssh-connection") != 0 || 602 !sshkey_equal(expected_key, mkey) || 603 sshkey_type_from_name(pkalg) != expected_key->type) { 604 r = SSH_ERR_INVALID_FORMAT; 605 goto out; 606 } 607 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 608 if ((r = sshkey_froms(b, &hostkey)) != 0) 609 goto out; 610 } else if (strcmp(method, "publickey") != 0) { 611 r = SSH_ERR_INVALID_FORMAT; 612 goto out; 613 } 614 if (sshbuf_len(b) != 0) { 615 r = SSH_ERR_INVALID_FORMAT; 616 goto out; 617 } 618 /* success */ 619 r = 0; 620 debug3_f("well formed userauth"); 621 if (userp != NULL) { 622 *userp = user; 623 user = NULL; 624 } 625 if (sess_idp != NULL) { 626 *sess_idp = sess_id; 627 sess_id = NULL; 628 } 629 if (hostkeyp != NULL) { 630 *hostkeyp = hostkey; 631 hostkey = NULL; 632 } 633 out: 634 sshbuf_free(b); 635 sshbuf_free(sess_id); 636 free(user); 637 free(service); 638 free(method); 639 free(pkalg); 640 sshkey_free(mkey); 641 sshkey_free(hostkey); 642 return r; 643 } 644 645 /* 646 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 647 * Note: does not modify buffer. 648 */ 649 static int 650 parse_sshsig_request(struct sshbuf *msg) 651 { 652 int r; 653 struct sshbuf *b; 654 655 if ((b = sshbuf_fromb(msg)) == NULL) 656 fatal_f("sshbuf_fromb"); 657 658 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 659 (r = sshbuf_consume(b, 6)) != 0 || 660 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 661 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 662 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 663 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 664 goto out; 665 if (sshbuf_len(b) != 0) { 666 r = SSH_ERR_INVALID_FORMAT; 667 goto out; 668 } 669 /* success */ 670 r = 0; 671 out: 672 sshbuf_free(b); 673 return r; 674 } 675 676 /* 677 * This function inspects a message to be signed by a FIDO key that has a 678 * web-like application string (i.e. one that does not begin with "ssh:". 679 * It checks that the message is one of those expected for SSH operations 680 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 681 * for the web. 682 */ 683 static int 684 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 685 { 686 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 687 debug_f("signed data matches public key userauth request"); 688 return 1; 689 } 690 if (parse_sshsig_request(data) == 0) { 691 debug_f("signed data matches SSHSIG signature request"); 692 return 1; 693 } 694 695 /* XXX check CA signature operation */ 696 697 error("web-origin key attempting to sign non-SSH message"); 698 return 0; 699 } 700 701 static int 702 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 703 { 704 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 705 return SSH_ERR_INVALID_ARGUMENT; 706 if (sshbuf_len(a) != sshbuf_len(b)) 707 return SSH_ERR_INVALID_FORMAT; 708 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 709 return SSH_ERR_INVALID_FORMAT; 710 return 0; 711 } 712 713 /* ssh2 only */ 714 static void 715 process_sign_request2(SocketEntry *e) 716 { 717 u_char *signature = NULL; 718 size_t slen = 0; 719 u_int compat = 0, flags; 720 int r, ok = -1, retried = 0; 721 char *fp = NULL, *pin = NULL, *prompt = NULL; 722 char *user = NULL, *sig_dest = NULL; 723 const char *fwd_host = NULL, *dest_host = NULL; 724 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 725 struct sshkey *key = NULL, *hostkey = NULL; 726 struct identity *id; 727 struct notifier_ctx *notifier = NULL; 728 729 debug_f("entering"); 730 731 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 732 fatal_f("sshbuf_new failed"); 733 if ((r = sshkey_froms(e->request, &key)) != 0 || 734 (r = sshbuf_get_stringb(e->request, data)) != 0 || 735 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 736 error_fr(r, "parse"); 737 goto send; 738 } 739 740 if ((id = lookup_identity(key)) == NULL) { 741 verbose_f("%s key not found", sshkey_type(key)); 742 goto send; 743 } 744 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 745 SSH_FP_DEFAULT)) == NULL) 746 fatal_f("fingerprint failed"); 747 748 if (id->ndest_constraints != 0) { 749 if (e->nsession_ids == 0) { 750 logit_f("refusing use of destination-constrained key " 751 "to sign on unbound connection"); 752 goto send; 753 } 754 if (parse_userauth_request(data, key, &user, &sid, 755 &hostkey) != 0) { 756 logit_f("refusing use of destination-constrained key " 757 "to sign an unidentified signature"); 758 goto send; 759 } 760 /* XXX logspam */ 761 debug_f("user=%s", user); 762 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 763 goto send; 764 /* XXX display fwd_host/dest_host in askpass UI */ 765 /* 766 * Ensure that the session ID is the most recent one 767 * registered on the socket - it should have been bound by 768 * ssh immediately before userauth. 769 */ 770 if (buf_equal(sid, 771 e->session_ids[e->nsession_ids - 1].sid) != 0) { 772 error_f("unexpected session ID (%zu listed) on " 773 "signature request for target user %s with " 774 "key %s %s", e->nsession_ids, user, 775 sshkey_type(id->key), fp); 776 goto send; 777 } 778 /* 779 * Ensure that the hostkey embedded in the signature matches 780 * the one most recently bound to the socket. An exception is 781 * made for the initial forwarding hop. 782 */ 783 if (e->nsession_ids > 1 && hostkey == NULL) { 784 error_f("refusing use of destination-constrained key: " 785 "no hostkey recorded in signature for forwarded " 786 "connection"); 787 goto send; 788 } 789 if (hostkey != NULL && !sshkey_equal(hostkey, 790 e->session_ids[e->nsession_ids - 1].key)) { 791 error_f("refusing use of destination-constrained key: " 792 "mismatch between hostkey in request and most " 793 "recently bound session"); 794 goto send; 795 } 796 xasprintf(&sig_dest, "public key authentication request for " 797 "user \"%s\" to listed host", user); 798 } 799 if (id->confirm && confirm_key(id, sig_dest) != 0) { 800 verbose_f("user refused key"); 801 goto send; 802 } 803 if (sshkey_is_sk(id->key)) { 804 if (strncmp(id->key->sk_application, "ssh:", 4) != 0 && 805 !check_websafe_message_contents(key, data)) { 806 /* error already logged */ 807 goto send; 808 } 809 if ((id->key->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) { 810 /* XXX include sig_dest */ 811 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 812 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 813 " and confirm user presence " : " ", 814 sshkey_type(id->key), fp); 815 pin = read_passphrase(prompt, RP_USE_ASKPASS); 816 free(prompt); 817 prompt = NULL; 818 } else if ((id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { 819 notifier = notify_start(0, 820 "Confirm user presence for key %s %s%s%s", 821 sshkey_type(id->key), fp, 822 sig_dest == NULL ? "" : "\n", 823 sig_dest == NULL ? "" : sig_dest); 824 } 825 } 826 retry_pin: 827 if ((r = sshkey_sign(id->key, &signature, &slen, 828 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 829 id->sk_provider, pin, compat)) != 0) { 830 debug_fr(r, "sshkey_sign"); 831 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 832 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 833 if (notifier) { 834 notify_complete(notifier, NULL); 835 notifier = NULL; 836 } 837 /* XXX include sig_dest */ 838 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 839 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 840 " and confirm user presence " : " ", 841 sshkey_type(id->key), fp); 842 pin = read_passphrase(prompt, RP_USE_ASKPASS); 843 retried = 1; 844 goto retry_pin; 845 } 846 error_fr(r, "sshkey_sign"); 847 goto send; 848 } 849 /* Success */ 850 ok = 0; 851 send: 852 notify_complete(notifier, "User presence confirmed"); 853 854 if (ok == 0) { 855 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 856 (r = sshbuf_put_string(msg, signature, slen)) != 0) 857 fatal_fr(r, "compose"); 858 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 859 fatal_fr(r, "compose failure"); 860 861 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 862 fatal_fr(r, "enqueue"); 863 864 sshbuf_free(sid); 865 sshbuf_free(data); 866 sshbuf_free(msg); 867 sshkey_free(key); 868 sshkey_free(hostkey); 869 free(fp); 870 free(signature); 871 free(sig_dest); 872 free(user); 873 free(prompt); 874 if (pin != NULL) 875 freezero(pin, strlen(pin)); 876 } 877 878 /* shared */ 879 static void 880 process_remove_identity(SocketEntry *e) 881 { 882 int r, success = 0; 883 struct sshkey *key = NULL; 884 Identity *id; 885 886 debug2_f("entering"); 887 if ((r = sshkey_froms(e->request, &key)) != 0) { 888 error_fr(r, "parse key"); 889 goto done; 890 } 891 if ((id = lookup_identity(key)) == NULL) { 892 debug_f("key not found"); 893 goto done; 894 } 895 /* identity not visible, cannot be removed */ 896 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 897 goto done; /* error already logged */ 898 /* We have this key, free it. */ 899 if (idtab->nentries < 1) 900 fatal_f("internal error: nentries %d", idtab->nentries); 901 TAILQ_REMOVE(&idtab->idlist, id, next); 902 free_identity(id); 903 idtab->nentries--; 904 success = 1; 905 done: 906 sshkey_free(key); 907 send_status(e, success); 908 } 909 910 static void 911 process_remove_all_identities(SocketEntry *e) 912 { 913 Identity *id; 914 915 debug2_f("entering"); 916 /* Loop over all identities and clear the keys. */ 917 for (id = TAILQ_FIRST(&idtab->idlist); id; 918 id = TAILQ_FIRST(&idtab->idlist)) { 919 TAILQ_REMOVE(&idtab->idlist, id, next); 920 free_identity(id); 921 } 922 923 /* Mark that there are no identities. */ 924 idtab->nentries = 0; 925 926 /* Send success. */ 927 send_status(e, 1); 928 } 929 930 /* removes expired keys and returns number of seconds until the next expiry */ 931 static time_t 932 reaper(void) 933 { 934 time_t deadline = 0, now = monotime(); 935 Identity *id, *nxt; 936 937 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 938 nxt = TAILQ_NEXT(id, next); 939 if (id->death == 0) 940 continue; 941 if (now >= id->death) { 942 debug("expiring key '%s'", id->comment); 943 TAILQ_REMOVE(&idtab->idlist, id, next); 944 free_identity(id); 945 idtab->nentries--; 946 } else 947 deadline = (deadline == 0) ? id->death : 948 MINIMUM(deadline, id->death); 949 } 950 if (deadline == 0 || deadline <= now) 951 return 0; 952 else 953 return (deadline - now); 954 } 955 956 static int 957 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 958 { 959 u_char key_is_ca; 960 size_t elen = 0; 961 int r; 962 struct sshkey *k = NULL; 963 char *fp; 964 965 memset(dch, '\0', sizeof(*dch)); 966 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 967 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 968 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 969 error_fr(r, "parse"); 970 goto out; 971 } 972 if (elen != 0) { 973 error_f("unsupported extensions (len %zu)", elen); 974 r = SSH_ERR_FEATURE_UNSUPPORTED; 975 goto out; 976 } 977 if (*dch->hostname == '\0') { 978 free(dch->hostname); 979 dch->hostname = NULL; 980 } 981 if (*dch->user == '\0') { 982 free(dch->user); 983 dch->user = NULL; 984 } 985 while (sshbuf_len(b) != 0) { 986 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 987 dch->nkeys + 1, sizeof(*dch->keys)); 988 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 989 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 990 if ((r = sshkey_froms(b, &k)) != 0 || 991 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 992 goto out; 993 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 994 SSH_FP_DEFAULT)) == NULL) 995 fatal_f("fingerprint failed"); 996 debug3_f("%s%s%s: adding %skey %s %s", 997 dch->user == NULL ? "" : dch->user, 998 dch->user == NULL ? "" : "@", 999 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1000 free(fp); 1001 dch->keys[dch->nkeys] = k; 1002 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1003 dch->nkeys++; 1004 k = NULL; /* transferred */ 1005 } 1006 /* success */ 1007 r = 0; 1008 out: 1009 sshkey_free(k); 1010 return r; 1011 } 1012 1013 static int 1014 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1015 { 1016 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1017 int r; 1018 size_t elen = 0; 1019 1020 debug3_f("entering"); 1021 1022 memset(dc, '\0', sizeof(*dc)); 1023 if ((r = sshbuf_froms(m, &b)) != 0 || 1024 (r = sshbuf_froms(b, &frombuf)) != 0 || 1025 (r = sshbuf_froms(b, &tobuf)) != 0 || 1026 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1027 error_fr(r, "parse"); 1028 goto out; 1029 } 1030 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) || 1031 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0)) 1032 goto out; /* already logged */ 1033 if (elen != 0) { 1034 error_f("unsupported extensions (len %zu)", elen); 1035 r = SSH_ERR_FEATURE_UNSUPPORTED; 1036 goto out; 1037 } 1038 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1039 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1040 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1041 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1042 /* check consistency */ 1043 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1044 dc->from.user != NULL) { 1045 error_f("inconsistent \"from\" specification"); 1046 r = SSH_ERR_INVALID_FORMAT; 1047 goto out; 1048 } 1049 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1050 error_f("incomplete \"to\" specification"); 1051 r = SSH_ERR_INVALID_FORMAT; 1052 goto out; 1053 } 1054 /* success */ 1055 r = 0; 1056 out: 1057 sshbuf_free(b); 1058 sshbuf_free(frombuf); 1059 sshbuf_free(tobuf); 1060 return r; 1061 } 1062 1063 static int 1064 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1065 struct dest_constraint **dcsp, size_t *ndcsp) 1066 { 1067 char *ext_name = NULL; 1068 int r; 1069 struct sshbuf *b = NULL; 1070 1071 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1072 error_fr(r, "parse constraint extension"); 1073 goto out; 1074 } 1075 debug_f("constraint ext %s", ext_name); 1076 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1077 if (sk_providerp == NULL) { 1078 error_f("%s not valid here", ext_name); 1079 r = SSH_ERR_INVALID_FORMAT; 1080 goto out; 1081 } 1082 if (*sk_providerp != NULL) { 1083 error_f("%s already set", ext_name); 1084 r = SSH_ERR_INVALID_FORMAT; 1085 goto out; 1086 } 1087 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1088 error_fr(r, "parse %s", ext_name); 1089 goto out; 1090 } 1091 } else if (strcmp(ext_name, 1092 "restrict-destination-v00@openssh.com") == 0) { 1093 if (*dcsp != NULL) { 1094 error_f("%s already set", ext_name); 1095 goto out; 1096 } 1097 if ((r = sshbuf_froms(m, &b)) != 0) { 1098 error_fr(r, "parse %s outer", ext_name); 1099 goto out; 1100 } 1101 while (sshbuf_len(b) != 0) { 1102 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1103 error_f("too many %s constraints", ext_name); 1104 goto out; 1105 } 1106 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1107 sizeof(**dcsp)); 1108 if ((r = parse_dest_constraint(b, 1109 *dcsp + (*ndcsp)++)) != 0) 1110 goto out; /* error already logged */ 1111 } 1112 } else { 1113 error_f("unsupported constraint \"%s\"", ext_name); 1114 r = SSH_ERR_FEATURE_UNSUPPORTED; 1115 goto out; 1116 } 1117 /* success */ 1118 r = 0; 1119 out: 1120 free(ext_name); 1121 sshbuf_free(b); 1122 return r; 1123 } 1124 1125 static int 1126 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1127 u_int *secondsp, int *confirmp, char **sk_providerp, 1128 struct dest_constraint **dcsp, size_t *ndcsp) 1129 { 1130 u_char ctype; 1131 int r; 1132 u_int seconds, maxsign = 0; 1133 1134 while (sshbuf_len(m)) { 1135 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1136 error_fr(r, "parse constraint type"); 1137 goto out; 1138 } 1139 switch (ctype) { 1140 case SSH_AGENT_CONSTRAIN_LIFETIME: 1141 if (*deathp != 0) { 1142 error_f("lifetime already set"); 1143 r = SSH_ERR_INVALID_FORMAT; 1144 goto out; 1145 } 1146 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1147 error_fr(r, "parse lifetime constraint"); 1148 goto out; 1149 } 1150 *deathp = monotime() + seconds; 1151 *secondsp = seconds; 1152 break; 1153 case SSH_AGENT_CONSTRAIN_CONFIRM: 1154 if (*confirmp != 0) { 1155 error_f("confirm already set"); 1156 r = SSH_ERR_INVALID_FORMAT; 1157 goto out; 1158 } 1159 *confirmp = 1; 1160 break; 1161 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1162 if (k == NULL) { 1163 error_f("maxsign not valid here"); 1164 r = SSH_ERR_INVALID_FORMAT; 1165 goto out; 1166 } 1167 if (maxsign != 0) { 1168 error_f("maxsign already set"); 1169 r = SSH_ERR_INVALID_FORMAT; 1170 goto out; 1171 } 1172 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1173 error_fr(r, "parse maxsign constraint"); 1174 goto out; 1175 } 1176 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1177 error_fr(r, "enable maxsign"); 1178 goto out; 1179 } 1180 break; 1181 case SSH_AGENT_CONSTRAIN_EXTENSION: 1182 if ((r = parse_key_constraint_extension(m, 1183 sk_providerp, dcsp, ndcsp)) != 0) 1184 goto out; /* error already logged */ 1185 break; 1186 default: 1187 error_f("Unknown constraint %d", ctype); 1188 r = SSH_ERR_FEATURE_UNSUPPORTED; 1189 goto out; 1190 } 1191 } 1192 /* success */ 1193 r = 0; 1194 out: 1195 return r; 1196 } 1197 1198 static void 1199 process_add_identity(SocketEntry *e) 1200 { 1201 Identity *id; 1202 int success = 0, confirm = 0; 1203 char *fp, *comment = NULL, *sk_provider = NULL; 1204 char canonical_provider[PATH_MAX]; 1205 time_t death = 0; 1206 u_int seconds = 0; 1207 struct dest_constraint *dest_constraints = NULL; 1208 size_t ndest_constraints = 0; 1209 struct sshkey *k = NULL; 1210 int r = SSH_ERR_INTERNAL_ERROR; 1211 1212 debug2_f("entering"); 1213 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1214 k == NULL || 1215 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1216 error_fr(r, "parse"); 1217 goto out; 1218 } 1219 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1220 &sk_provider, &dest_constraints, &ndest_constraints) != 0) { 1221 error_f("failed to parse constraints"); 1222 sshbuf_reset(e->request); 1223 goto out; 1224 } 1225 1226 if (sk_provider != NULL) { 1227 if (!sshkey_is_sk(k)) { 1228 error("Cannot add provider: %s is not an " 1229 "authenticator-hosted key", sshkey_type(k)); 1230 goto out; 1231 } 1232 if (strcasecmp(sk_provider, "internal") == 0) { 1233 debug_f("internal provider"); 1234 } else { 1235 if (realpath(sk_provider, canonical_provider) == NULL) { 1236 verbose("failed provider \"%.100s\": " 1237 "realpath: %s", sk_provider, 1238 strerror(errno)); 1239 goto out; 1240 } 1241 free(sk_provider); 1242 sk_provider = xstrdup(canonical_provider); 1243 if (match_pattern_list(sk_provider, 1244 allowed_providers, 0) != 1) { 1245 error("Refusing add key: " 1246 "provider %s not allowed", sk_provider); 1247 goto out; 1248 } 1249 } 1250 } 1251 if ((r = sshkey_shield_private(k)) != 0) { 1252 error_fr(r, "shield private"); 1253 goto out; 1254 } 1255 if (lifetime && !death) 1256 death = monotime() + lifetime; 1257 if ((id = lookup_identity(k)) == NULL) { 1258 id = xcalloc(1, sizeof(Identity)); 1259 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1260 /* Increment the number of identities. */ 1261 idtab->nentries++; 1262 } else { 1263 /* identity not visible, do not update */ 1264 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1265 goto out; /* error already logged */ 1266 /* key state might have been updated */ 1267 sshkey_free(id->key); 1268 free(id->comment); 1269 free(id->sk_provider); 1270 free_dest_constraints(id->dest_constraints, 1271 id->ndest_constraints); 1272 } 1273 /* success */ 1274 id->key = k; 1275 id->comment = comment; 1276 id->death = death; 1277 id->confirm = confirm; 1278 id->sk_provider = sk_provider; 1279 id->dest_constraints = dest_constraints; 1280 id->ndest_constraints = ndest_constraints; 1281 1282 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1283 SSH_FP_DEFAULT)) == NULL) 1284 fatal_f("sshkey_fingerprint failed"); 1285 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1286 "(provider: %s) (destination constraints: %zu)", 1287 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1288 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1289 free(fp); 1290 /* transferred */ 1291 k = NULL; 1292 comment = NULL; 1293 sk_provider = NULL; 1294 dest_constraints = NULL; 1295 ndest_constraints = 0; 1296 success = 1; 1297 out: 1298 free(sk_provider); 1299 free(comment); 1300 sshkey_free(k); 1301 free_dest_constraints(dest_constraints, ndest_constraints); 1302 send_status(e, success); 1303 } 1304 1305 /* XXX todo: encrypt sensitive data with passphrase */ 1306 static void 1307 process_lock_agent(SocketEntry *e, int lock) 1308 { 1309 int r, success = 0, delay; 1310 char *passwd; 1311 u_char passwdhash[LOCK_SIZE]; 1312 static u_int fail_count = 0; 1313 size_t pwlen; 1314 1315 debug2_f("entering"); 1316 /* 1317 * This is deliberately fatal: the user has requested that we lock, 1318 * but we can't parse their request properly. The only safe thing to 1319 * do is abort. 1320 */ 1321 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1322 fatal_fr(r, "parse"); 1323 if (pwlen == 0) { 1324 debug("empty password not supported"); 1325 } else if (locked && !lock) { 1326 if (bcrypt_pbkdf(passwd, pwlen, (uint8_t *)lock_salt, sizeof(lock_salt), 1327 (uint8_t *)passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1328 fatal("bcrypt_pbkdf"); 1329 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1330 debug("agent unlocked"); 1331 locked = 0; 1332 fail_count = 0; 1333 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1334 success = 1; 1335 } else { 1336 /* delay in 0.1s increments up to 10s */ 1337 if (fail_count < 100) 1338 fail_count++; 1339 delay = 100000 * fail_count; 1340 debug("unlock failed, delaying %0.1lf seconds", 1341 (double)delay/1000000); 1342 usleep(delay); 1343 } 1344 explicit_bzero(passwdhash, sizeof(passwdhash)); 1345 } else if (!locked && lock) { 1346 debug("agent locked"); 1347 locked = 1; 1348 arc4random_buf(lock_salt, sizeof(lock_salt)); 1349 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1350 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1351 fatal("bcrypt_pbkdf"); 1352 success = 1; 1353 } 1354 freezero(passwd, pwlen); 1355 send_status(e, success); 1356 } 1357 1358 static void 1359 no_identities(SocketEntry *e) 1360 { 1361 struct sshbuf *msg; 1362 int r; 1363 1364 if ((msg = sshbuf_new()) == NULL) 1365 fatal_f("sshbuf_new failed"); 1366 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1367 (r = sshbuf_put_u32(msg, 0)) != 0 || 1368 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1369 fatal_fr(r, "compose"); 1370 sshbuf_free(msg); 1371 } 1372 1373 #ifdef ENABLE_PKCS11 1374 static void 1375 process_add_smartcard_key(SocketEntry *e) 1376 { 1377 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1378 char **comments = NULL; 1379 int r, i, count = 0, success = 0, confirm = 0; 1380 u_int seconds = 0; 1381 time_t death = 0; 1382 struct sshkey **keys = NULL, *k; 1383 Identity *id; 1384 struct dest_constraint *dest_constraints = NULL; 1385 size_t ndest_constraints = 0; 1386 1387 debug2_f("entering"); 1388 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1389 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1390 error_fr(r, "parse"); 1391 goto send; 1392 } 1393 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1394 NULL, &dest_constraints, &ndest_constraints) != 0) { 1395 error_f("failed to parse constraints"); 1396 goto send; 1397 } 1398 if (realpath(provider, canonical_provider) == NULL) { 1399 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1400 provider, strerror(errno)); 1401 goto send; 1402 } 1403 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1404 verbose("refusing PKCS#11 add of \"%.100s\": " 1405 "provider not allowed", canonical_provider); 1406 goto send; 1407 } 1408 debug_f("add %.100s", canonical_provider); 1409 if (lifetime && !death) 1410 death = monotime() + lifetime; 1411 1412 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1413 for (i = 0; i < count; i++) { 1414 k = keys[i]; 1415 if (lookup_identity(k) == NULL) { 1416 id = xcalloc(1, sizeof(Identity)); 1417 id->key = k; 1418 keys[i] = NULL; /* transferred */ 1419 id->provider = xstrdup(canonical_provider); 1420 if (*comments[i] != '\0') { 1421 id->comment = comments[i]; 1422 comments[i] = NULL; /* transferred */ 1423 } else { 1424 id->comment = xstrdup(canonical_provider); 1425 } 1426 id->death = death; 1427 id->confirm = confirm; 1428 id->dest_constraints = dest_constraints; 1429 id->ndest_constraints = ndest_constraints; 1430 dest_constraints = NULL; /* transferred */ 1431 ndest_constraints = 0; 1432 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1433 idtab->nentries++; 1434 success = 1; 1435 } 1436 /* XXX update constraints for existing keys */ 1437 sshkey_free(keys[i]); 1438 free(comments[i]); 1439 } 1440 send: 1441 free(pin); 1442 free(provider); 1443 free(keys); 1444 free(comments); 1445 free_dest_constraints(dest_constraints, ndest_constraints); 1446 send_status(e, success); 1447 } 1448 1449 static void 1450 process_remove_smartcard_key(SocketEntry *e) 1451 { 1452 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1453 int r, success = 0; 1454 Identity *id, *nxt; 1455 1456 debug2_f("entering"); 1457 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1458 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1459 error_fr(r, "parse"); 1460 goto send; 1461 } 1462 free(pin); 1463 1464 if (realpath(provider, canonical_provider) == NULL) { 1465 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1466 provider, strerror(errno)); 1467 goto send; 1468 } 1469 1470 debug_f("remove %.100s", canonical_provider); 1471 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1472 nxt = TAILQ_NEXT(id, next); 1473 /* Skip file--based keys */ 1474 if (id->provider == NULL) 1475 continue; 1476 if (!strcmp(canonical_provider, id->provider)) { 1477 TAILQ_REMOVE(&idtab->idlist, id, next); 1478 free_identity(id); 1479 idtab->nentries--; 1480 } 1481 } 1482 if (pkcs11_del_provider(canonical_provider) == 0) 1483 success = 1; 1484 else 1485 error_f("pkcs11_del_provider failed"); 1486 send: 1487 free(provider); 1488 send_status(e, success); 1489 } 1490 #endif /* ENABLE_PKCS11 */ 1491 1492 static int 1493 process_ext_session_bind(SocketEntry *e) 1494 { 1495 int r, sid_match, key_match; 1496 struct sshkey *key = NULL; 1497 struct sshbuf *sid = NULL, *sig = NULL; 1498 char *fp = NULL; 1499 size_t i; 1500 u_char fwd = 0; 1501 1502 debug2_f("entering"); 1503 if ((r = sshkey_froms(e->request, &key)) != 0 || 1504 (r = sshbuf_froms(e->request, &sid)) != 0 || 1505 (r = sshbuf_froms(e->request, &sig)) != 0 || 1506 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1507 error_fr(r, "parse"); 1508 goto out; 1509 } 1510 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1511 SSH_FP_DEFAULT)) == NULL) 1512 fatal_f("fingerprint failed"); 1513 /* check signature with hostkey on session ID */ 1514 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1515 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1516 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1517 goto out; 1518 } 1519 /* check whether sid/key already recorded */ 1520 for (i = 0; i < e->nsession_ids; i++) { 1521 if (!e->session_ids[i].forwarded) { 1522 error_f("attempt to bind session ID to socket " 1523 "previously bound for authentication attempt"); 1524 r = -1; 1525 goto out; 1526 } 1527 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1528 key_match = sshkey_equal(key, e->session_ids[i].key); 1529 if (sid_match && key_match) { 1530 debug_f("session ID already recorded for %s %s", 1531 sshkey_type(key), fp); 1532 r = 0; 1533 goto out; 1534 } else if (sid_match) { 1535 error_f("session ID recorded against different key " 1536 "for %s %s", sshkey_type(key), fp); 1537 r = -1; 1538 goto out; 1539 } 1540 /* 1541 * new sid with previously-seen key can happen, e.g. multiple 1542 * connections to the same host. 1543 */ 1544 } 1545 /* record new key/sid */ 1546 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1547 error_f("too many session IDs recorded"); 1548 goto out; 1549 } 1550 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1551 e->nsession_ids + 1, sizeof(*e->session_ids)); 1552 i = e->nsession_ids++; 1553 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1554 AGENT_MAX_SESSION_IDS); 1555 e->session_ids[i].key = key; 1556 e->session_ids[i].forwarded = fwd != 0; 1557 key = NULL; /* transferred */ 1558 /* can't transfer sid; it's refcounted and scoped to request's life */ 1559 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1560 fatal_f("sshbuf_new"); 1561 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1562 fatal_fr(r, "sshbuf_putb session ID"); 1563 /* success */ 1564 r = 0; 1565 out: 1566 sshkey_free(key); 1567 sshbuf_free(sid); 1568 sshbuf_free(sig); 1569 return r == 0 ? 1 : 0; 1570 } 1571 1572 static void 1573 process_extension(SocketEntry *e) 1574 { 1575 int r, success = 0; 1576 char *name; 1577 1578 debug2_f("entering"); 1579 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1580 error_fr(r, "parse"); 1581 goto send; 1582 } 1583 if (strcmp(name, "session-bind@openssh.com") == 0) 1584 success = process_ext_session_bind(e); 1585 else 1586 debug_f("unsupported extension \"%s\"", name); 1587 free(name); 1588 send: 1589 send_status(e, success); 1590 } 1591 /* 1592 * dispatch incoming message. 1593 * returns 1 on success, 0 for incomplete messages or -1 on error. 1594 */ 1595 static int 1596 process_message(u_int socknum) 1597 { 1598 u_int msg_len; 1599 u_char type; 1600 const u_char *cp; 1601 int r; 1602 SocketEntry *e; 1603 1604 if (socknum >= sockets_alloc) 1605 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1606 e = &sockets[socknum]; 1607 1608 if (sshbuf_len(e->input) < 5) 1609 return 0; /* Incomplete message header. */ 1610 cp = sshbuf_ptr(e->input); 1611 msg_len = PEEK_U32(cp); 1612 if (msg_len > AGENT_MAX_LEN) { 1613 debug_f("socket %u (fd=%d) message too long %u > %u", 1614 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1615 return -1; 1616 } 1617 if (sshbuf_len(e->input) < msg_len + 4) 1618 return 0; /* Incomplete message body. */ 1619 1620 /* move the current input to e->request */ 1621 sshbuf_reset(e->request); 1622 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1623 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1624 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1625 r == SSH_ERR_STRING_TOO_LARGE) { 1626 error_fr(r, "parse"); 1627 return -1; 1628 } 1629 fatal_fr(r, "parse"); 1630 } 1631 1632 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1633 1634 /* check whether agent is locked */ 1635 if (locked && type != SSH_AGENTC_UNLOCK) { 1636 sshbuf_reset(e->request); 1637 switch (type) { 1638 case SSH2_AGENTC_REQUEST_IDENTITIES: 1639 /* send empty lists */ 1640 no_identities(e); 1641 break; 1642 default: 1643 /* send a fail message for all other request types */ 1644 send_status(e, 0); 1645 } 1646 return 1; 1647 } 1648 1649 switch (type) { 1650 case SSH_AGENTC_LOCK: 1651 case SSH_AGENTC_UNLOCK: 1652 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1653 break; 1654 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1655 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1656 break; 1657 /* ssh2 */ 1658 case SSH2_AGENTC_SIGN_REQUEST: 1659 process_sign_request2(e); 1660 break; 1661 case SSH2_AGENTC_REQUEST_IDENTITIES: 1662 process_request_identities(e); 1663 break; 1664 case SSH2_AGENTC_ADD_IDENTITY: 1665 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1666 process_add_identity(e); 1667 break; 1668 case SSH2_AGENTC_REMOVE_IDENTITY: 1669 process_remove_identity(e); 1670 break; 1671 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1672 process_remove_all_identities(e); 1673 break; 1674 #ifdef ENABLE_PKCS11 1675 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1676 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1677 process_add_smartcard_key(e); 1678 break; 1679 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1680 process_remove_smartcard_key(e); 1681 break; 1682 #endif /* ENABLE_PKCS11 */ 1683 case SSH_AGENTC_EXTENSION: 1684 process_extension(e); 1685 break; 1686 default: 1687 /* Unknown message. Respond with failure. */ 1688 error("Unknown message %d", type); 1689 sshbuf_reset(e->request); 1690 send_status(e, 0); 1691 break; 1692 } 1693 return 1; 1694 } 1695 1696 static void 1697 new_socket(sock_type type, int fd) 1698 { 1699 u_int i, old_alloc, new_alloc; 1700 1701 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1702 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1703 set_nonblock(fd); 1704 1705 if (fd > max_fd) 1706 max_fd = fd; 1707 1708 for (i = 0; i < sockets_alloc; i++) 1709 if (sockets[i].type == AUTH_UNUSED) { 1710 sockets[i].fd = fd; 1711 if ((sockets[i].input = sshbuf_new()) == NULL || 1712 (sockets[i].output = sshbuf_new()) == NULL || 1713 (sockets[i].request = sshbuf_new()) == NULL) 1714 fatal_f("sshbuf_new failed"); 1715 sockets[i].type = type; 1716 return; 1717 } 1718 old_alloc = sockets_alloc; 1719 new_alloc = sockets_alloc + 10; 1720 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1721 sizeof(sockets[0])); 1722 for (i = old_alloc; i < new_alloc; i++) 1723 sockets[i].type = AUTH_UNUSED; 1724 sockets_alloc = new_alloc; 1725 sockets[old_alloc].fd = fd; 1726 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1727 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1728 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1729 fatal_f("sshbuf_new failed"); 1730 sockets[old_alloc].type = type; 1731 } 1732 1733 static int 1734 handle_socket_read(u_int socknum) 1735 { 1736 struct sockaddr_un sunaddr; 1737 socklen_t slen; 1738 uid_t euid; 1739 gid_t egid; 1740 int fd; 1741 1742 slen = sizeof(sunaddr); 1743 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1744 if (fd == -1) { 1745 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1746 return -1; 1747 } 1748 if (getpeereid(fd, &euid, &egid) == -1) { 1749 error("getpeereid %d failed: %s", fd, strerror(errno)); 1750 close(fd); 1751 return -1; 1752 } 1753 if ((euid != 0) && (getuid() != euid)) { 1754 error("uid mismatch: peer euid %u != uid %u", 1755 (u_int) euid, (u_int) getuid()); 1756 close(fd); 1757 return -1; 1758 } 1759 new_socket(AUTH_CONNECTION, fd); 1760 return 0; 1761 } 1762 1763 static int 1764 handle_conn_read(u_int socknum) 1765 { 1766 char buf[AGENT_RBUF_LEN]; 1767 ssize_t len; 1768 int r; 1769 1770 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1771 if (len == -1) { 1772 if (errno == EAGAIN || errno == EINTR) 1773 return 0; 1774 error_f("read error on socket %u (fd %d): %s", 1775 socknum, sockets[socknum].fd, strerror(errno)); 1776 } 1777 return -1; 1778 } 1779 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1780 fatal_fr(r, "compose"); 1781 explicit_bzero(buf, sizeof(buf)); 1782 for (;;) { 1783 if ((r = process_message(socknum)) == -1) 1784 return -1; 1785 else if (r == 0) 1786 break; 1787 } 1788 return 0; 1789 } 1790 1791 static int 1792 handle_conn_write(u_int socknum) 1793 { 1794 ssize_t len; 1795 int r; 1796 1797 if (sshbuf_len(sockets[socknum].output) == 0) 1798 return 0; /* shouldn't happen */ 1799 if ((len = write(sockets[socknum].fd, 1800 sshbuf_ptr(sockets[socknum].output), 1801 sshbuf_len(sockets[socknum].output))) <= 0) { 1802 if (len == -1) { 1803 if (errno == EAGAIN || errno == EINTR) 1804 return 0; 1805 error_f("read error on socket %u (fd %d): %s", 1806 socknum, sockets[socknum].fd, strerror(errno)); 1807 } 1808 return -1; 1809 } 1810 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 1811 fatal_fr(r, "consume"); 1812 return 0; 1813 } 1814 1815 static void 1816 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 1817 { 1818 size_t i; 1819 u_int socknum, activefds = npfd; 1820 1821 for (i = 0; i < npfd; i++) { 1822 if (pfd[i].revents == 0) 1823 continue; 1824 /* Find sockets entry */ 1825 for (socknum = 0; socknum < sockets_alloc; socknum++) { 1826 if (sockets[socknum].type != AUTH_SOCKET && 1827 sockets[socknum].type != AUTH_CONNECTION) 1828 continue; 1829 if (pfd[i].fd == sockets[socknum].fd) 1830 break; 1831 } 1832 if (socknum >= sockets_alloc) { 1833 error_f("no socket for fd %d", pfd[i].fd); 1834 continue; 1835 } 1836 /* Process events */ 1837 switch (sockets[socknum].type) { 1838 case AUTH_SOCKET: 1839 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 1840 break; 1841 if (npfd > maxfds) { 1842 debug3("out of fds (active %u >= limit %u); " 1843 "skipping accept", activefds, maxfds); 1844 break; 1845 } 1846 if (handle_socket_read(socknum) == 0) 1847 activefds++; 1848 break; 1849 case AUTH_CONNECTION: 1850 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 1851 handle_conn_read(socknum) != 0) 1852 goto close_sock; 1853 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 1854 handle_conn_write(socknum) != 0) { 1855 close_sock: 1856 if (activefds == 0) 1857 fatal("activefds == 0 at close_sock"); 1858 close_socket(&sockets[socknum]); 1859 activefds--; 1860 break; 1861 } 1862 break; 1863 default: 1864 break; 1865 } 1866 } 1867 } 1868 1869 static int 1870 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 1871 { 1872 struct pollfd *pfd = *pfdp; 1873 size_t i, j, npfd = 0; 1874 time_t deadline; 1875 int r; 1876 1877 /* Count active sockets */ 1878 for (i = 0; i < sockets_alloc; i++) { 1879 switch (sockets[i].type) { 1880 case AUTH_SOCKET: 1881 case AUTH_CONNECTION: 1882 npfd++; 1883 break; 1884 case AUTH_UNUSED: 1885 break; 1886 default: 1887 fatal("Unknown socket type %d", sockets[i].type); 1888 break; 1889 } 1890 } 1891 if (npfd != *npfdp && 1892 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 1893 fatal_f("recallocarray failed"); 1894 *pfdp = pfd; 1895 *npfdp = npfd; 1896 1897 for (i = j = 0; i < sockets_alloc; i++) { 1898 switch (sockets[i].type) { 1899 case AUTH_SOCKET: 1900 if (npfd > maxfds) { 1901 debug3("out of fds (active %zu >= limit %u); " 1902 "skipping arming listener", npfd, maxfds); 1903 break; 1904 } 1905 pfd[j].fd = sockets[i].fd; 1906 pfd[j].revents = 0; 1907 pfd[j].events = POLLIN; 1908 j++; 1909 break; 1910 case AUTH_CONNECTION: 1911 pfd[j].fd = sockets[i].fd; 1912 pfd[j].revents = 0; 1913 /* 1914 * Only prepare to read if we can handle a full-size 1915 * input read buffer and enqueue a max size reply.. 1916 */ 1917 if ((r = sshbuf_check_reserve(sockets[i].input, 1918 AGENT_RBUF_LEN)) == 0 && 1919 (r = sshbuf_check_reserve(sockets[i].output, 1920 AGENT_MAX_LEN)) == 0) 1921 pfd[j].events = POLLIN; 1922 else if (r != SSH_ERR_NO_BUFFER_SPACE) 1923 fatal_fr(r, "reserve"); 1924 if (sshbuf_len(sockets[i].output) > 0) 1925 pfd[j].events |= POLLOUT; 1926 j++; 1927 break; 1928 default: 1929 break; 1930 } 1931 } 1932 deadline = reaper(); 1933 if (parent_alive_interval != 0) 1934 deadline = (deadline == 0) ? parent_alive_interval : 1935 MINIMUM(deadline, parent_alive_interval); 1936 if (deadline == 0) { 1937 *timeoutp = -1; /* INFTIM */ 1938 } else { 1939 if (deadline > INT_MAX / 1000) 1940 *timeoutp = INT_MAX / 1000; 1941 else 1942 *timeoutp = deadline * 1000; 1943 } 1944 return (1); 1945 } 1946 1947 static void 1948 cleanup_socket(void) 1949 { 1950 if (cleanup_pid != 0 && getpid() != cleanup_pid) 1951 return; 1952 debug_f("cleanup"); 1953 if (socket_name[0]) 1954 unlink(socket_name); 1955 if (socket_dir[0]) 1956 rmdir(socket_dir); 1957 } 1958 1959 void 1960 cleanup_exit(int i) 1961 { 1962 cleanup_socket(); 1963 _exit(i); 1964 } 1965 1966 /*ARGSUSED*/ 1967 __dead static void 1968 cleanup_handler(int sig) 1969 { 1970 cleanup_socket(); 1971 #ifdef ENABLE_PKCS11 1972 pkcs11_terminate(); 1973 #endif 1974 _exit(2); 1975 } 1976 1977 static void 1978 check_parent_exists(void) 1979 { 1980 /* 1981 * If our parent has exited then getppid() will return (pid_t)1, 1982 * so testing for that should be safe. 1983 */ 1984 if (parent_pid != -1 && getppid() != parent_pid) { 1985 /* printf("Parent has died - Authentication agent exiting.\n"); */ 1986 cleanup_socket(); 1987 _exit(2); 1988 } 1989 } 1990 1991 __dead static void 1992 usage(void) 1993 { 1994 fprintf(stderr, 1995 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 1996 " [-P allowed_providers] [-t life]\n" 1997 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n" 1998 " [-t life] command [arg ...]\n" 1999 " ssh-agent [-c | -s] -k\n"); 2000 exit(1); 2001 } 2002 2003 static void 2004 csh_setenv(const char *name, const char *value) 2005 { 2006 printf("setenv %s %s;\n", name, value); 2007 } 2008 2009 static void 2010 csh_unsetenv(const char *name) 2011 { 2012 printf("unsetenv %s;\n", name); 2013 } 2014 2015 static void 2016 sh_setenv(const char *name, const char *value) 2017 { 2018 printf("%s=%s; export %s;\n", name, value, name); 2019 } 2020 2021 static void 2022 sh_unsetenv(const char *name) 2023 { 2024 printf("unset %s;\n", name); 2025 } 2026 int 2027 main(int ac, char **av) 2028 { 2029 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2030 int sock, ch, result, saved_errno; 2031 char *shell, *pidstr, *agentsocket = NULL; 2032 struct rlimit rlim; 2033 void (*f_setenv)(const char *, const char *); 2034 void (*f_unsetenv)(const char *); 2035 extern int optind; 2036 extern char *optarg; 2037 pid_t pid; 2038 char pidstrbuf[1 + 3 * sizeof pid]; 2039 size_t len; 2040 mode_t prev_mask; 2041 int timeout = -1; /* INFTIM */ 2042 struct pollfd *pfd = NULL; 2043 size_t npfd = 0; 2044 u_int maxfds; 2045 2046 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2047 sanitise_stdfd(); 2048 2049 /* drop */ 2050 setegid(getgid()); 2051 setgid(getgid()); 2052 2053 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2054 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2055 2056 #ifdef WITH_OPENSSL 2057 OpenSSL_add_all_algorithms(); 2058 #endif 2059 2060 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2061 switch (ch) { 2062 case 'E': 2063 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2064 if (fingerprint_hash == -1) 2065 fatal("Invalid hash algorithm \"%s\"", optarg); 2066 break; 2067 case 'c': 2068 if (s_flag) 2069 usage(); 2070 c_flag++; 2071 break; 2072 case 'k': 2073 k_flag++; 2074 break; 2075 case 'O': 2076 if (strcmp(optarg, "no-restrict-websafe") == 0) 2077 restrict_websafe = 0; 2078 else 2079 fatal("Unknown -O option"); 2080 break; 2081 case 'P': 2082 if (allowed_providers != NULL) 2083 fatal("-P option already specified"); 2084 allowed_providers = xstrdup(optarg); 2085 break; 2086 case 's': 2087 if (c_flag) 2088 usage(); 2089 s_flag++; 2090 break; 2091 case 'd': 2092 if (d_flag || D_flag) 2093 usage(); 2094 d_flag++; 2095 break; 2096 case 'D': 2097 if (d_flag || D_flag) 2098 usage(); 2099 D_flag++; 2100 break; 2101 case 'a': 2102 agentsocket = optarg; 2103 break; 2104 case 't': 2105 if ((lifetime = convtime(optarg)) == -1) { 2106 fprintf(stderr, "Invalid lifetime\n"); 2107 usage(); 2108 } 2109 break; 2110 default: 2111 usage(); 2112 } 2113 } 2114 ac -= optind; 2115 av += optind; 2116 2117 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2118 usage(); 2119 2120 if (allowed_providers == NULL) 2121 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2122 2123 if (ac == 0 && !c_flag && !s_flag) { 2124 shell = getenv("SHELL"); 2125 if (shell != NULL && (len = strlen(shell)) > 2 && 2126 strncmp(shell + len - 3, "csh", 3) == 0) 2127 c_flag = 1; 2128 } 2129 if (c_flag) { 2130 f_setenv = csh_setenv; 2131 f_unsetenv = csh_unsetenv; 2132 } else { 2133 f_setenv = sh_setenv; 2134 f_unsetenv = sh_unsetenv; 2135 } 2136 if (k_flag) { 2137 const char *errstr = NULL; 2138 2139 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2140 if (pidstr == NULL) { 2141 fprintf(stderr, "%s not set, cannot kill agent\n", 2142 SSH_AGENTPID_ENV_NAME); 2143 exit(1); 2144 } 2145 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2146 if (errstr) { 2147 fprintf(stderr, 2148 "%s=\"%s\", which is not a good PID: %s\n", 2149 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2150 exit(1); 2151 } 2152 if (kill(pid, SIGTERM) == -1) { 2153 perror("kill"); 2154 exit(1); 2155 } 2156 (*f_unsetenv)(SSH_AUTHSOCKET_ENV_NAME); 2157 (*f_unsetenv)(SSH_AGENTPID_ENV_NAME); 2158 printf("echo Agent pid %ld killed;\n", (long)pid); 2159 exit(0); 2160 } 2161 2162 /* 2163 * Minimum file descriptors: 2164 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2165 * a few spare for libc / stack protectors / sanitisers, etc. 2166 */ 2167 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2168 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2169 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2170 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2171 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2172 2173 parent_pid = getpid(); 2174 2175 if (agentsocket == NULL) { 2176 /* Create private directory for agent socket */ 2177 mktemp_proto(socket_dir, sizeof(socket_dir)); 2178 if (mkdtemp(socket_dir) == NULL) { 2179 perror("mkdtemp: private socket dir"); 2180 exit(1); 2181 } 2182 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2183 (long)parent_pid); 2184 } else { 2185 /* Try to use specified agent socket */ 2186 socket_dir[0] = '\0'; 2187 strlcpy(socket_name, agentsocket, sizeof socket_name); 2188 } 2189 2190 /* 2191 * Create socket early so it will exist before command gets run from 2192 * the parent. 2193 */ 2194 prev_mask = umask(0177); 2195 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2196 if (sock < 0) { 2197 /* XXX - unix_listener() calls error() not perror() */ 2198 *socket_name = '\0'; /* Don't unlink any existing file */ 2199 cleanup_exit(1); 2200 } 2201 umask(prev_mask); 2202 2203 /* 2204 * Fork, and have the parent execute the command, if any, or present 2205 * the socket data. The child continues as the authentication agent. 2206 */ 2207 if (D_flag || d_flag) { 2208 log_init(__progname, 2209 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2210 SYSLOG_FACILITY_AUTH, 1); 2211 if (c_flag) 2212 printf("setenv %s %s;\n", 2213 SSH_AUTHSOCKET_ENV_NAME, socket_name); 2214 else 2215 printf("%s=%s; export %s;\n", 2216 SSH_AUTHSOCKET_ENV_NAME, socket_name, 2217 SSH_AUTHSOCKET_ENV_NAME); 2218 printf("echo Agent pid %ld;\n", (long)parent_pid); 2219 fflush(stdout); 2220 goto skip; 2221 } 2222 pid = fork(); 2223 if (pid == -1) { 2224 perror("fork"); 2225 cleanup_exit(1); 2226 } 2227 if (pid != 0) { /* Parent - execute the given command. */ 2228 close(sock); 2229 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2230 if (ac == 0) { 2231 (*f_setenv)(SSH_AUTHSOCKET_ENV_NAME, socket_name); 2232 (*f_setenv)(SSH_AGENTPID_ENV_NAME, pidstrbuf); 2233 printf("echo Agent pid %ld;\n", (long)pid); 2234 exit(0); 2235 } 2236 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2237 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2238 perror("setenv"); 2239 exit(1); 2240 } 2241 execvp(av[0], av); 2242 perror(av[0]); 2243 exit(1); 2244 } 2245 /* child */ 2246 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2247 2248 if (setsid() == -1) { 2249 error("setsid: %s", strerror(errno)); 2250 cleanup_exit(1); 2251 } 2252 2253 (void)chdir("/"); 2254 if (stdfd_devnull(1, 1, 1) == -1) 2255 error_f("stdfd_devnull failed"); 2256 2257 /* deny core dumps, since memory contains unencrypted private keys */ 2258 rlim.rlim_cur = rlim.rlim_max = 0; 2259 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2260 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2261 cleanup_exit(1); 2262 } 2263 2264 skip: 2265 2266 cleanup_pid = getpid(); 2267 2268 #ifdef ENABLE_PKCS11 2269 pkcs11_init(0); 2270 #endif 2271 new_socket(AUTH_SOCKET, sock); 2272 if (ac > 0) 2273 parent_alive_interval = 10; 2274 idtab_init(); 2275 ssh_signal(SIGPIPE, SIG_IGN); 2276 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2277 ssh_signal(SIGHUP, cleanup_handler); 2278 ssh_signal(SIGTERM, cleanup_handler); 2279 2280 #ifdef __OpenBSD__ 2281 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2282 fatal("%s: pledge: %s", __progname, strerror(errno)); 2283 #endif 2284 2285 while (1) { 2286 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2287 result = poll(pfd, npfd, timeout); 2288 saved_errno = errno; 2289 if (parent_alive_interval != 0) 2290 check_parent_exists(); 2291 (void) reaper(); /* remove expired keys */ 2292 if (result == -1) { 2293 if (saved_errno == EINTR) 2294 continue; 2295 fatal("poll: %s", strerror(saved_errno)); 2296 } else if (result > 0) 2297 after_poll(pfd, npfd, maxfds); 2298 } 2299 /* NOTREACHED */ 2300 } 2301