1 /* $OpenBSD: ssh-agent.c,v 1.306 2024/03/09 05:12:13 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * The authentication agent program. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 39 #include <sys/types.h> 40 #include <sys/resource.h> 41 #include <sys/stat.h> 42 #include <sys/socket.h> 43 #include <sys/wait.h> 44 #ifdef HAVE_SYS_TIME_H 45 # include <sys/time.h> 46 #endif 47 #ifdef HAVE_SYS_UN_H 48 # include <sys/un.h> 49 #endif 50 #include "openbsd-compat/sys-queue.h" 51 52 #ifdef WITH_OPENSSL 53 #include <openssl/evp.h> 54 #include "openbsd-compat/openssl-compat.h" 55 #endif 56 57 #include <errno.h> 58 #include <fcntl.h> 59 #include <limits.h> 60 #ifdef HAVE_PATHS_H 61 # include <paths.h> 62 #endif 63 #ifdef HAVE_POLL_H 64 # include <poll.h> 65 #endif 66 #include <signal.h> 67 #include <stdarg.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <time.h> 71 #include <string.h> 72 #include <unistd.h> 73 #ifdef HAVE_UTIL_H 74 # include <util.h> 75 #endif 76 77 #include "xmalloc.h" 78 #include "ssh.h" 79 #include "ssh2.h" 80 #include "sshbuf.h" 81 #include "sshkey.h" 82 #include "authfd.h" 83 #include "log.h" 84 #include "misc.h" 85 #include "digest.h" 86 #include "ssherr.h" 87 #include "match.h" 88 #include "msg.h" 89 #include "pathnames.h" 90 #include "ssh-pkcs11.h" 91 #include "sk-api.h" 92 #include "myproposal.h" 93 94 #ifndef DEFAULT_ALLOWED_PROVIDERS 95 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" 96 #endif 97 98 /* Maximum accepted message length */ 99 #define AGENT_MAX_LEN (256*1024) 100 /* Maximum bytes to read from client socket */ 101 #define AGENT_RBUF_LEN (4096) 102 /* Maximum number of recorded session IDs/hostkeys per connection */ 103 #define AGENT_MAX_SESSION_IDS 16 104 /* Maximum size of session ID */ 105 #define AGENT_MAX_SID_LEN 128 106 /* Maximum number of destination constraints to accept on a key */ 107 #define AGENT_MAX_DEST_CONSTRAINTS 1024 108 /* Maximum number of associated certificate constraints to accept on a key */ 109 #define AGENT_MAX_EXT_CERTS 1024 110 111 /* XXX store hostkey_sid in a refcounted tree */ 112 113 typedef enum { 114 AUTH_UNUSED = 0, 115 AUTH_SOCKET = 1, 116 AUTH_CONNECTION = 2, 117 } sock_type; 118 119 struct hostkey_sid { 120 struct sshkey *key; 121 struct sshbuf *sid; 122 int forwarded; 123 }; 124 125 typedef struct socket_entry { 126 int fd; 127 sock_type type; 128 struct sshbuf *input; 129 struct sshbuf *output; 130 struct sshbuf *request; 131 size_t nsession_ids; 132 struct hostkey_sid *session_ids; 133 int session_bind_attempted; 134 } SocketEntry; 135 136 u_int sockets_alloc = 0; 137 SocketEntry *sockets = NULL; 138 139 typedef struct identity { 140 TAILQ_ENTRY(identity) next; 141 struct sshkey *key; 142 char *comment; 143 char *provider; 144 time_t death; 145 u_int confirm; 146 char *sk_provider; 147 struct dest_constraint *dest_constraints; 148 size_t ndest_constraints; 149 } Identity; 150 151 struct idtable { 152 int nentries; 153 TAILQ_HEAD(idqueue, identity) idlist; 154 }; 155 156 /* private key table */ 157 struct idtable *idtab; 158 159 int max_fd = 0; 160 161 /* pid of shell == parent of agent */ 162 pid_t parent_pid = -1; 163 time_t parent_alive_interval = 0; 164 165 sig_atomic_t signalled = 0; 166 167 /* pid of process for which cleanup_socket is applicable */ 168 pid_t cleanup_pid = 0; 169 170 /* pathname and directory for AUTH_SOCKET */ 171 char socket_name[PATH_MAX]; 172 char socket_dir[PATH_MAX]; 173 174 /* Pattern-list of allowed PKCS#11/Security key paths */ 175 static char *allowed_providers; 176 177 /* 178 * Allows PKCS11 providers or SK keys that use non-internal providers to 179 * be added over a remote connection (identified by session-bind@openssh.com). 180 */ 181 static int remote_add_provider; 182 183 /* locking */ 184 #define LOCK_SIZE 32 185 #define LOCK_SALT_SIZE 16 186 #define LOCK_ROUNDS 1 187 int locked = 0; 188 u_char lock_pwhash[LOCK_SIZE]; 189 u_char lock_salt[LOCK_SALT_SIZE]; 190 191 extern char *__progname; 192 193 /* Default lifetime in seconds (0 == forever) */ 194 static int lifetime = 0; 195 196 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 197 198 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 199 static int restrict_websafe = 1; 200 201 static void 202 close_socket(SocketEntry *e) 203 { 204 size_t i; 205 206 close(e->fd); 207 sshbuf_free(e->input); 208 sshbuf_free(e->output); 209 sshbuf_free(e->request); 210 for (i = 0; i < e->nsession_ids; i++) { 211 sshkey_free(e->session_ids[i].key); 212 sshbuf_free(e->session_ids[i].sid); 213 } 214 free(e->session_ids); 215 memset(e, '\0', sizeof(*e)); 216 e->fd = -1; 217 e->type = AUTH_UNUSED; 218 } 219 220 static void 221 idtab_init(void) 222 { 223 idtab = xcalloc(1, sizeof(*idtab)); 224 TAILQ_INIT(&idtab->idlist); 225 idtab->nentries = 0; 226 } 227 228 static void 229 free_dest_constraint_hop(struct dest_constraint_hop *dch) 230 { 231 u_int i; 232 233 if (dch == NULL) 234 return; 235 free(dch->user); 236 free(dch->hostname); 237 for (i = 0; i < dch->nkeys; i++) 238 sshkey_free(dch->keys[i]); 239 free(dch->keys); 240 free(dch->key_is_ca); 241 } 242 243 static void 244 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 245 { 246 size_t i; 247 248 for (i = 0; i < ndcs; i++) { 249 free_dest_constraint_hop(&dcs[i].from); 250 free_dest_constraint_hop(&dcs[i].to); 251 } 252 free(dcs); 253 } 254 255 #ifdef ENABLE_PKCS11 256 static void 257 dup_dest_constraint_hop(const struct dest_constraint_hop *dch, 258 struct dest_constraint_hop *out) 259 { 260 u_int i; 261 int r; 262 263 out->user = dch->user == NULL ? NULL : xstrdup(dch->user); 264 out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname); 265 out->is_ca = dch->is_ca; 266 out->nkeys = dch->nkeys; 267 out->keys = out->nkeys == 0 ? NULL : 268 xcalloc(out->nkeys, sizeof(*out->keys)); 269 out->key_is_ca = out->nkeys == 0 ? NULL : 270 xcalloc(out->nkeys, sizeof(*out->key_is_ca)); 271 for (i = 0; i < dch->nkeys; i++) { 272 if (dch->keys[i] != NULL && 273 (r = sshkey_from_private(dch->keys[i], 274 &(out->keys[i]))) != 0) 275 fatal_fr(r, "copy key"); 276 out->key_is_ca[i] = dch->key_is_ca[i]; 277 } 278 } 279 280 static struct dest_constraint * 281 dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs) 282 { 283 size_t i; 284 struct dest_constraint *ret; 285 286 if (ndcs == 0) 287 return NULL; 288 ret = xcalloc(ndcs, sizeof(*ret)); 289 for (i = 0; i < ndcs; i++) { 290 dup_dest_constraint_hop(&dcs[i].from, &ret[i].from); 291 dup_dest_constraint_hop(&dcs[i].to, &ret[i].to); 292 } 293 return ret; 294 } 295 #endif /* ENABLE_PKCS11 */ 296 297 #ifdef DEBUG_CONSTRAINTS 298 static void 299 dump_dest_constraint_hop(const struct dest_constraint_hop *dch) 300 { 301 u_int i; 302 char *fp; 303 304 debug_f("user %s hostname %s is_ca %d nkeys %u", 305 dch->user == NULL ? "(null)" : dch->user, 306 dch->hostname == NULL ? "(null)" : dch->hostname, 307 dch->is_ca, dch->nkeys); 308 for (i = 0; i < dch->nkeys; i++) { 309 fp = NULL; 310 if (dch->keys[i] != NULL && 311 (fp = sshkey_fingerprint(dch->keys[i], 312 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) 313 fatal_f("fingerprint failed"); 314 debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys, 315 dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]), 316 dch->keys[i] == NULL ? "" : " ", 317 dch->keys[i] == NULL ? "none" : fp, 318 dch->key_is_ca[i]); 319 free(fp); 320 } 321 } 322 #endif /* DEBUG_CONSTRAINTS */ 323 324 static void 325 dump_dest_constraints(const char *context, 326 const struct dest_constraint *dcs, size_t ndcs) 327 { 328 #ifdef DEBUG_CONSTRAINTS 329 size_t i; 330 331 debug_f("%s: %zu constraints", context, ndcs); 332 for (i = 0; i < ndcs; i++) { 333 debug_f("constraint %zu / %zu: from: ", i, ndcs); 334 dump_dest_constraint_hop(&dcs[i].from); 335 debug_f("constraint %zu / %zu: to: ", i, ndcs); 336 dump_dest_constraint_hop(&dcs[i].to); 337 } 338 debug_f("done for %s", context); 339 #endif /* DEBUG_CONSTRAINTS */ 340 } 341 342 static void 343 free_identity(Identity *id) 344 { 345 sshkey_free(id->key); 346 free(id->provider); 347 free(id->comment); 348 free(id->sk_provider); 349 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 350 free(id); 351 } 352 353 /* 354 * Match 'key' against the key/CA list in a destination constraint hop 355 * Returns 0 on success or -1 otherwise. 356 */ 357 static int 358 match_key_hop(const char *tag, const struct sshkey *key, 359 const struct dest_constraint_hop *dch) 360 { 361 const char *reason = NULL; 362 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 363 u_int i; 364 char *fp; 365 366 if (key == NULL) 367 return -1; 368 /* XXX logspam */ 369 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 370 SSH_FP_DEFAULT)) == NULL) 371 fatal_f("fingerprint failed"); 372 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 373 tag, hostname, sshkey_type(key), fp, dch->nkeys); 374 free(fp); 375 for (i = 0; i < dch->nkeys; i++) { 376 if (dch->keys[i] == NULL) 377 return -1; 378 /* XXX logspam */ 379 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 380 SSH_FP_DEFAULT)) == NULL) 381 fatal_f("fingerprint failed"); 382 debug3_f("%s: key %u: %s%s %s", tag, i, 383 dch->key_is_ca[i] ? "CA " : "", 384 sshkey_type(dch->keys[i]), fp); 385 free(fp); 386 if (!sshkey_is_cert(key)) { 387 /* plain key */ 388 if (dch->key_is_ca[i] || 389 !sshkey_equal(key, dch->keys[i])) 390 continue; 391 return 0; 392 } 393 /* certificate */ 394 if (!dch->key_is_ca[i]) 395 continue; 396 if (key->cert == NULL || key->cert->signature_key == NULL) 397 return -1; /* shouldn't happen */ 398 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 399 continue; 400 if (sshkey_cert_check_host(key, hostname, 1, 401 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 402 debug_f("cert %s / hostname %s rejected: %s", 403 key->cert->key_id, hostname, reason); 404 continue; 405 } 406 return 0; 407 } 408 return -1; 409 } 410 411 /* Check destination constraints on an identity against the hostkey/user */ 412 static int 413 permitted_by_dest_constraints(const struct sshkey *fromkey, 414 const struct sshkey *tokey, Identity *id, const char *user, 415 const char **hostnamep) 416 { 417 size_t i; 418 struct dest_constraint *d; 419 420 if (hostnamep != NULL) 421 *hostnamep = NULL; 422 for (i = 0; i < id->ndest_constraints; i++) { 423 d = id->dest_constraints + i; 424 /* XXX remove logspam */ 425 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 426 i, d->from.user ? d->from.user : "", 427 d->from.user ? "@" : "", 428 d->from.hostname ? d->from.hostname : "(ORIGIN)", 429 d->from.nkeys, 430 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 431 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 432 433 /* Match 'from' key */ 434 if (fromkey == NULL) { 435 /* We are matching the first hop */ 436 if (d->from.hostname != NULL || d->from.nkeys != 0) 437 continue; 438 } else if (match_key_hop("from", fromkey, &d->from) != 0) 439 continue; 440 441 /* Match 'to' key */ 442 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 443 continue; 444 445 /* Match user if specified */ 446 if (d->to.user != NULL && user != NULL && 447 !match_pattern(user, d->to.user)) 448 continue; 449 450 /* successfully matched this constraint */ 451 if (hostnamep != NULL) 452 *hostnamep = d->to.hostname; 453 debug2_f("allowed for hostname %s", 454 d->to.hostname == NULL ? "*" : d->to.hostname); 455 return 0; 456 } 457 /* no match */ 458 debug2_f("%s identity \"%s\" not permitted for this destination", 459 sshkey_type(id->key), id->comment); 460 return -1; 461 } 462 463 /* 464 * Check whether hostkeys on a SocketEntry and the optionally specified user 465 * are permitted by the destination constraints on the Identity. 466 * Returns 0 on success or -1 otherwise. 467 */ 468 static int 469 identity_permitted(Identity *id, SocketEntry *e, char *user, 470 const char **forward_hostnamep, const char **last_hostnamep) 471 { 472 size_t i; 473 const char **hp; 474 struct hostkey_sid *hks; 475 const struct sshkey *fromkey = NULL; 476 const char *test_user; 477 char *fp1, *fp2; 478 479 /* XXX remove logspam */ 480 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 481 "%zu constraints", sshkey_type(id->key), id->comment, 482 e->nsession_ids, id->ndest_constraints); 483 if (id->ndest_constraints == 0) 484 return 0; /* unconstrained */ 485 if (e->session_bind_attempted && e->nsession_ids == 0) { 486 error_f("previous session bind failed on socket"); 487 return -1; 488 } 489 if (e->nsession_ids == 0) 490 return 0; /* local use */ 491 /* 492 * Walk through the hops recorded by session_id and try to find a 493 * constraint that satisfies each. 494 */ 495 for (i = 0; i < e->nsession_ids; i++) { 496 hks = e->session_ids + i; 497 if (hks->key == NULL) 498 fatal_f("internal error: no bound key"); 499 /* XXX remove logspam */ 500 fp1 = fp2 = NULL; 501 if (fromkey != NULL && 502 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 503 SSH_FP_DEFAULT)) == NULL) 504 fatal_f("fingerprint failed"); 505 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 506 SSH_FP_DEFAULT)) == NULL) 507 fatal_f("fingerprint failed"); 508 debug3_f("socketentry fd=%d, entry %zu %s, " 509 "from hostkey %s %s to user %s hostkey %s %s", 510 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 511 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 512 fromkey ? fp1 : "", user ? user : "(ANY)", 513 sshkey_type(hks->key), fp2); 514 free(fp1); 515 free(fp2); 516 /* 517 * Record the hostnames for the initial forwarding and 518 * the final destination. 519 */ 520 hp = NULL; 521 if (i == e->nsession_ids - 1) 522 hp = last_hostnamep; 523 else if (i == 0) 524 hp = forward_hostnamep; 525 /* Special handling for final recorded binding */ 526 test_user = NULL; 527 if (i == e->nsession_ids - 1) { 528 /* Can only check user at final hop */ 529 test_user = user; 530 /* 531 * user is only presented for signature requests. 532 * If this is the case, make sure last binding is not 533 * for a forwarding. 534 */ 535 if (hks->forwarded && user != NULL) { 536 error_f("tried to sign on forwarding hop"); 537 return -1; 538 } 539 } else if (!hks->forwarded) { 540 error_f("tried to forward though signing bind"); 541 return -1; 542 } 543 if (permitted_by_dest_constraints(fromkey, hks->key, id, 544 test_user, hp) != 0) 545 return -1; 546 fromkey = hks->key; 547 } 548 /* 549 * Another special case: if the last bound session ID was for a 550 * forwarding, and this function is not being called to check a sign 551 * request (i.e. no 'user' supplied), then only permit the key if 552 * there is a permission that would allow it to be used at another 553 * destination. This hides keys that are allowed to be used to 554 * authenticate *to* a host but not permitted for *use* beyond it. 555 */ 556 hks = &e->session_ids[e->nsession_ids - 1]; 557 if (hks->forwarded && user == NULL && 558 permitted_by_dest_constraints(hks->key, NULL, id, 559 NULL, NULL) != 0) { 560 debug3_f("key permitted at host but not after"); 561 return -1; 562 } 563 564 /* success */ 565 return 0; 566 } 567 568 static int 569 socket_is_remote(SocketEntry *e) 570 { 571 return e->session_bind_attempted || (e->nsession_ids != 0); 572 } 573 574 /* return matching private key for given public key */ 575 static Identity * 576 lookup_identity(struct sshkey *key) 577 { 578 Identity *id; 579 580 TAILQ_FOREACH(id, &idtab->idlist, next) { 581 if (sshkey_equal(key, id->key)) 582 return (id); 583 } 584 return (NULL); 585 } 586 587 /* Check confirmation of keysign request */ 588 static int 589 confirm_key(Identity *id, const char *extra) 590 { 591 char *p; 592 int ret = -1; 593 594 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 595 if (p != NULL && 596 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 597 id->comment, p, 598 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 599 ret = 0; 600 free(p); 601 602 return (ret); 603 } 604 605 static void 606 send_status(SocketEntry *e, int success) 607 { 608 int r; 609 610 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 611 (r = sshbuf_put_u8(e->output, success ? 612 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 613 fatal_fr(r, "compose"); 614 } 615 616 /* send list of supported public keys to 'client' */ 617 static void 618 process_request_identities(SocketEntry *e) 619 { 620 Identity *id; 621 struct sshbuf *msg, *keys; 622 int r; 623 u_int i = 0, nentries = 0; 624 char *fp; 625 626 debug2_f("entering"); 627 628 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 629 fatal_f("sshbuf_new failed"); 630 TAILQ_FOREACH(id, &idtab->idlist, next) { 631 if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT, 632 SSH_FP_DEFAULT)) == NULL) 633 fatal_f("fingerprint failed"); 634 debug_f("key %u / %u: %s %s", i++, idtab->nentries, 635 sshkey_ssh_name(id->key), fp); 636 dump_dest_constraints(__func__, 637 id->dest_constraints, id->ndest_constraints); 638 free(fp); 639 /* identity not visible, don't include in response */ 640 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 641 continue; 642 if ((r = sshkey_puts_opts(id->key, keys, 643 SSHKEY_SERIALIZE_INFO)) != 0 || 644 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 645 error_fr(r, "compose key/comment"); 646 continue; 647 } 648 nentries++; 649 } 650 debug2_f("replying with %u allowed of %u available keys", 651 nentries, idtab->nentries); 652 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 653 (r = sshbuf_put_u32(msg, nentries)) != 0 || 654 (r = sshbuf_putb(msg, keys)) != 0) 655 fatal_fr(r, "compose"); 656 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 657 fatal_fr(r, "enqueue"); 658 sshbuf_free(msg); 659 sshbuf_free(keys); 660 } 661 662 663 static char * 664 agent_decode_alg(struct sshkey *key, u_int flags) 665 { 666 if (key->type == KEY_RSA) { 667 if (flags & SSH_AGENT_RSA_SHA2_256) 668 return "rsa-sha2-256"; 669 else if (flags & SSH_AGENT_RSA_SHA2_512) 670 return "rsa-sha2-512"; 671 } else if (key->type == KEY_RSA_CERT) { 672 if (flags & SSH_AGENT_RSA_SHA2_256) 673 return "rsa-sha2-256-cert-v01@openssh.com"; 674 else if (flags & SSH_AGENT_RSA_SHA2_512) 675 return "rsa-sha2-512-cert-v01@openssh.com"; 676 } 677 return NULL; 678 } 679 680 /* 681 * Attempt to parse the contents of a buffer as a SSH publickey userauth 682 * request, checking its contents for consistency and matching the embedded 683 * key against the one that is being used for signing. 684 * Note: does not modify msg buffer. 685 * Optionally extract the username, session ID and/or hostkey from the request. 686 */ 687 static int 688 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 689 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 690 { 691 struct sshbuf *b = NULL, *sess_id = NULL; 692 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 693 int r; 694 u_char t, sig_follows; 695 struct sshkey *mkey = NULL, *hostkey = NULL; 696 697 if (userp != NULL) 698 *userp = NULL; 699 if (sess_idp != NULL) 700 *sess_idp = NULL; 701 if (hostkeyp != NULL) 702 *hostkeyp = NULL; 703 if ((b = sshbuf_fromb(msg)) == NULL) 704 fatal_f("sshbuf_fromb"); 705 706 /* SSH userauth request */ 707 if ((r = sshbuf_froms(b, &sess_id)) != 0) 708 goto out; 709 if (sshbuf_len(sess_id) == 0) { 710 r = SSH_ERR_INVALID_FORMAT; 711 goto out; 712 } 713 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 714 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 715 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 716 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 717 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 718 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 719 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 720 goto out; 721 if (t != SSH2_MSG_USERAUTH_REQUEST || 722 sig_follows != 1 || 723 strcmp(service, "ssh-connection") != 0 || 724 !sshkey_equal(expected_key, mkey) || 725 sshkey_type_from_name(pkalg) != expected_key->type) { 726 r = SSH_ERR_INVALID_FORMAT; 727 goto out; 728 } 729 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 730 if ((r = sshkey_froms(b, &hostkey)) != 0) 731 goto out; 732 } else if (strcmp(method, "publickey") != 0) { 733 r = SSH_ERR_INVALID_FORMAT; 734 goto out; 735 } 736 if (sshbuf_len(b) != 0) { 737 r = SSH_ERR_INVALID_FORMAT; 738 goto out; 739 } 740 /* success */ 741 r = 0; 742 debug3_f("well formed userauth"); 743 if (userp != NULL) { 744 *userp = user; 745 user = NULL; 746 } 747 if (sess_idp != NULL) { 748 *sess_idp = sess_id; 749 sess_id = NULL; 750 } 751 if (hostkeyp != NULL) { 752 *hostkeyp = hostkey; 753 hostkey = NULL; 754 } 755 out: 756 sshbuf_free(b); 757 sshbuf_free(sess_id); 758 free(user); 759 free(service); 760 free(method); 761 free(pkalg); 762 sshkey_free(mkey); 763 sshkey_free(hostkey); 764 return r; 765 } 766 767 /* 768 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 769 * Note: does not modify buffer. 770 */ 771 static int 772 parse_sshsig_request(struct sshbuf *msg) 773 { 774 int r; 775 struct sshbuf *b; 776 777 if ((b = sshbuf_fromb(msg)) == NULL) 778 fatal_f("sshbuf_fromb"); 779 780 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 781 (r = sshbuf_consume(b, 6)) != 0 || 782 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 783 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 784 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 785 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 786 goto out; 787 if (sshbuf_len(b) != 0) { 788 r = SSH_ERR_INVALID_FORMAT; 789 goto out; 790 } 791 /* success */ 792 r = 0; 793 out: 794 sshbuf_free(b); 795 return r; 796 } 797 798 /* 799 * This function inspects a message to be signed by a FIDO key that has a 800 * web-like application string (i.e. one that does not begin with "ssh:". 801 * It checks that the message is one of those expected for SSH operations 802 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 803 * for the web. 804 */ 805 static int 806 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 807 { 808 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 809 debug_f("signed data matches public key userauth request"); 810 return 1; 811 } 812 if (parse_sshsig_request(data) == 0) { 813 debug_f("signed data matches SSHSIG signature request"); 814 return 1; 815 } 816 817 /* XXX check CA signature operation */ 818 819 error("web-origin key attempting to sign non-SSH message"); 820 return 0; 821 } 822 823 static int 824 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 825 { 826 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 827 return SSH_ERR_INVALID_ARGUMENT; 828 if (sshbuf_len(a) != sshbuf_len(b)) 829 return SSH_ERR_INVALID_FORMAT; 830 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 831 return SSH_ERR_INVALID_FORMAT; 832 return 0; 833 } 834 835 /* ssh2 only */ 836 static void 837 process_sign_request2(SocketEntry *e) 838 { 839 u_char *signature = NULL; 840 size_t slen = 0; 841 u_int compat = 0, flags; 842 int r, ok = -1, retried = 0; 843 char *fp = NULL, *pin = NULL, *prompt = NULL; 844 char *user = NULL, *sig_dest = NULL; 845 const char *fwd_host = NULL, *dest_host = NULL; 846 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 847 struct sshkey *key = NULL, *hostkey = NULL; 848 struct identity *id; 849 struct notifier_ctx *notifier = NULL; 850 851 debug_f("entering"); 852 853 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 854 fatal_f("sshbuf_new failed"); 855 if ((r = sshkey_froms(e->request, &key)) != 0 || 856 (r = sshbuf_get_stringb(e->request, data)) != 0 || 857 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 858 error_fr(r, "parse"); 859 goto send; 860 } 861 862 if ((id = lookup_identity(key)) == NULL) { 863 verbose_f("%s key not found", sshkey_type(key)); 864 goto send; 865 } 866 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 867 SSH_FP_DEFAULT)) == NULL) 868 fatal_f("fingerprint failed"); 869 870 if (id->ndest_constraints != 0) { 871 if (e->nsession_ids == 0) { 872 logit_f("refusing use of destination-constrained key " 873 "to sign on unbound connection"); 874 goto send; 875 } 876 if (parse_userauth_request(data, key, &user, &sid, 877 &hostkey) != 0) { 878 logit_f("refusing use of destination-constrained key " 879 "to sign an unidentified signature"); 880 goto send; 881 } 882 /* XXX logspam */ 883 debug_f("user=%s", user); 884 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 885 goto send; 886 /* XXX display fwd_host/dest_host in askpass UI */ 887 /* 888 * Ensure that the session ID is the most recent one 889 * registered on the socket - it should have been bound by 890 * ssh immediately before userauth. 891 */ 892 if (buf_equal(sid, 893 e->session_ids[e->nsession_ids - 1].sid) != 0) { 894 error_f("unexpected session ID (%zu listed) on " 895 "signature request for target user %s with " 896 "key %s %s", e->nsession_ids, user, 897 sshkey_type(id->key), fp); 898 goto send; 899 } 900 /* 901 * Ensure that the hostkey embedded in the signature matches 902 * the one most recently bound to the socket. An exception is 903 * made for the initial forwarding hop. 904 */ 905 if (e->nsession_ids > 1 && hostkey == NULL) { 906 error_f("refusing use of destination-constrained key: " 907 "no hostkey recorded in signature for forwarded " 908 "connection"); 909 goto send; 910 } 911 if (hostkey != NULL && !sshkey_equal(hostkey, 912 e->session_ids[e->nsession_ids - 1].key)) { 913 error_f("refusing use of destination-constrained key: " 914 "mismatch between hostkey in request and most " 915 "recently bound session"); 916 goto send; 917 } 918 xasprintf(&sig_dest, "public key authentication request for " 919 "user \"%s\" to listed host", user); 920 } 921 if (id->confirm && confirm_key(id, sig_dest) != 0) { 922 verbose_f("user refused key"); 923 goto send; 924 } 925 if (sshkey_is_sk(id->key)) { 926 if (restrict_websafe && 927 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 928 !check_websafe_message_contents(key, data)) { 929 /* error already logged */ 930 goto send; 931 } 932 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 933 notifier = notify_start(0, 934 "Confirm user presence for key %s %s%s%s", 935 sshkey_type(id->key), fp, 936 sig_dest == NULL ? "" : "\n", 937 sig_dest == NULL ? "" : sig_dest); 938 } 939 } 940 retry_pin: 941 if ((r = sshkey_sign(id->key, &signature, &slen, 942 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 943 id->sk_provider, pin, compat)) != 0) { 944 debug_fr(r, "sshkey_sign"); 945 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 946 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 947 notify_complete(notifier, NULL); 948 notifier = NULL; 949 /* XXX include sig_dest */ 950 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 951 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 952 " and confirm user presence " : " ", 953 sshkey_type(id->key), fp); 954 pin = read_passphrase(prompt, RP_USE_ASKPASS); 955 retried = 1; 956 goto retry_pin; 957 } 958 error_fr(r, "sshkey_sign"); 959 goto send; 960 } 961 /* Success */ 962 ok = 0; 963 debug_f("good signature"); 964 send: 965 notify_complete(notifier, "User presence confirmed"); 966 967 if (ok == 0) { 968 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 969 (r = sshbuf_put_string(msg, signature, slen)) != 0) 970 fatal_fr(r, "compose"); 971 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 972 fatal_fr(r, "compose failure"); 973 974 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 975 fatal_fr(r, "enqueue"); 976 977 sshbuf_free(sid); 978 sshbuf_free(data); 979 sshbuf_free(msg); 980 sshkey_free(key); 981 sshkey_free(hostkey); 982 free(fp); 983 free(signature); 984 free(sig_dest); 985 free(user); 986 free(prompt); 987 if (pin != NULL) 988 freezero(pin, strlen(pin)); 989 } 990 991 /* shared */ 992 static void 993 process_remove_identity(SocketEntry *e) 994 { 995 int r, success = 0; 996 struct sshkey *key = NULL; 997 Identity *id; 998 999 debug2_f("entering"); 1000 if ((r = sshkey_froms(e->request, &key)) != 0) { 1001 error_fr(r, "parse key"); 1002 goto done; 1003 } 1004 if ((id = lookup_identity(key)) == NULL) { 1005 debug_f("key not found"); 1006 goto done; 1007 } 1008 /* identity not visible, cannot be removed */ 1009 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1010 goto done; /* error already logged */ 1011 /* We have this key, free it. */ 1012 if (idtab->nentries < 1) 1013 fatal_f("internal error: nentries %d", idtab->nentries); 1014 TAILQ_REMOVE(&idtab->idlist, id, next); 1015 free_identity(id); 1016 idtab->nentries--; 1017 success = 1; 1018 done: 1019 sshkey_free(key); 1020 send_status(e, success); 1021 } 1022 1023 static void 1024 process_remove_all_identities(SocketEntry *e) 1025 { 1026 Identity *id; 1027 1028 debug2_f("entering"); 1029 /* Loop over all identities and clear the keys. */ 1030 for (id = TAILQ_FIRST(&idtab->idlist); id; 1031 id = TAILQ_FIRST(&idtab->idlist)) { 1032 TAILQ_REMOVE(&idtab->idlist, id, next); 1033 free_identity(id); 1034 } 1035 1036 /* Mark that there are no identities. */ 1037 idtab->nentries = 0; 1038 1039 /* Send success. */ 1040 send_status(e, 1); 1041 } 1042 1043 /* removes expired keys and returns number of seconds until the next expiry */ 1044 static time_t 1045 reaper(void) 1046 { 1047 time_t deadline = 0, now = monotime(); 1048 Identity *id, *nxt; 1049 1050 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1051 nxt = TAILQ_NEXT(id, next); 1052 if (id->death == 0) 1053 continue; 1054 if (now >= id->death) { 1055 debug("expiring key '%s'", id->comment); 1056 TAILQ_REMOVE(&idtab->idlist, id, next); 1057 free_identity(id); 1058 idtab->nentries--; 1059 } else 1060 deadline = (deadline == 0) ? id->death : 1061 MINIMUM(deadline, id->death); 1062 } 1063 if (deadline == 0 || deadline <= now) 1064 return 0; 1065 else 1066 return (deadline - now); 1067 } 1068 1069 static int 1070 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 1071 { 1072 u_char key_is_ca; 1073 size_t elen = 0; 1074 int r; 1075 struct sshkey *k = NULL; 1076 char *fp; 1077 1078 memset(dch, '\0', sizeof(*dch)); 1079 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 1080 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 1081 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1082 error_fr(r, "parse"); 1083 goto out; 1084 } 1085 if (elen != 0) { 1086 error_f("unsupported extensions (len %zu)", elen); 1087 r = SSH_ERR_FEATURE_UNSUPPORTED; 1088 goto out; 1089 } 1090 if (*dch->hostname == '\0') { 1091 free(dch->hostname); 1092 dch->hostname = NULL; 1093 } 1094 if (*dch->user == '\0') { 1095 free(dch->user); 1096 dch->user = NULL; 1097 } 1098 while (sshbuf_len(b) != 0) { 1099 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1100 dch->nkeys + 1, sizeof(*dch->keys)); 1101 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1102 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1103 if ((r = sshkey_froms(b, &k)) != 0 || 1104 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1105 goto out; 1106 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1107 SSH_FP_DEFAULT)) == NULL) 1108 fatal_f("fingerprint failed"); 1109 debug3_f("%s%s%s: adding %skey %s %s", 1110 dch->user == NULL ? "" : dch->user, 1111 dch->user == NULL ? "" : "@", 1112 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1113 free(fp); 1114 dch->keys[dch->nkeys] = k; 1115 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1116 dch->nkeys++; 1117 k = NULL; /* transferred */ 1118 } 1119 /* success */ 1120 r = 0; 1121 out: 1122 sshkey_free(k); 1123 return r; 1124 } 1125 1126 static int 1127 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1128 { 1129 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1130 int r; 1131 size_t elen = 0; 1132 1133 debug3_f("entering"); 1134 1135 memset(dc, '\0', sizeof(*dc)); 1136 if ((r = sshbuf_froms(m, &b)) != 0 || 1137 (r = sshbuf_froms(b, &frombuf)) != 0 || 1138 (r = sshbuf_froms(b, &tobuf)) != 0 || 1139 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1140 error_fr(r, "parse"); 1141 goto out; 1142 } 1143 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1144 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1145 goto out; /* already logged */ 1146 if (elen != 0) { 1147 error_f("unsupported extensions (len %zu)", elen); 1148 r = SSH_ERR_FEATURE_UNSUPPORTED; 1149 goto out; 1150 } 1151 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1152 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1153 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1154 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1155 /* check consistency */ 1156 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1157 dc->from.user != NULL) { 1158 error_f("inconsistent \"from\" specification"); 1159 r = SSH_ERR_INVALID_FORMAT; 1160 goto out; 1161 } 1162 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1163 error_f("incomplete \"to\" specification"); 1164 r = SSH_ERR_INVALID_FORMAT; 1165 goto out; 1166 } 1167 /* success */ 1168 r = 0; 1169 out: 1170 sshbuf_free(b); 1171 sshbuf_free(frombuf); 1172 sshbuf_free(tobuf); 1173 return r; 1174 } 1175 1176 static int 1177 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1178 struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp, 1179 struct sshkey ***certs, size_t *ncerts) 1180 { 1181 char *ext_name = NULL; 1182 int r; 1183 struct sshbuf *b = NULL; 1184 u_char v; 1185 struct sshkey *k; 1186 1187 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1188 error_fr(r, "parse constraint extension"); 1189 goto out; 1190 } 1191 debug_f("constraint ext %s", ext_name); 1192 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1193 if (sk_providerp == NULL) { 1194 error_f("%s not valid here", ext_name); 1195 r = SSH_ERR_INVALID_FORMAT; 1196 goto out; 1197 } 1198 if (*sk_providerp != NULL) { 1199 error_f("%s already set", ext_name); 1200 r = SSH_ERR_INVALID_FORMAT; 1201 goto out; 1202 } 1203 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1204 error_fr(r, "parse %s", ext_name); 1205 goto out; 1206 } 1207 } else if (strcmp(ext_name, 1208 "restrict-destination-v00@openssh.com") == 0) { 1209 if (*dcsp != NULL) { 1210 error_f("%s already set", ext_name); 1211 goto out; 1212 } 1213 if ((r = sshbuf_froms(m, &b)) != 0) { 1214 error_fr(r, "parse %s outer", ext_name); 1215 goto out; 1216 } 1217 while (sshbuf_len(b) != 0) { 1218 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1219 error_f("too many %s constraints", ext_name); 1220 goto out; 1221 } 1222 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1223 sizeof(**dcsp)); 1224 if ((r = parse_dest_constraint(b, 1225 *dcsp + (*ndcsp)++)) != 0) 1226 goto out; /* error already logged */ 1227 } 1228 } else if (strcmp(ext_name, 1229 "associated-certs-v00@openssh.com") == 0) { 1230 if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) { 1231 error_f("%s not valid here", ext_name); 1232 r = SSH_ERR_INVALID_FORMAT; 1233 goto out; 1234 } 1235 if (*certs != NULL) { 1236 error_f("%s already set", ext_name); 1237 goto out; 1238 } 1239 if ((r = sshbuf_get_u8(m, &v)) != 0 || 1240 (r = sshbuf_froms(m, &b)) != 0) { 1241 error_fr(r, "parse %s", ext_name); 1242 goto out; 1243 } 1244 *cert_onlyp = v != 0; 1245 while (sshbuf_len(b) != 0) { 1246 if (*ncerts >= AGENT_MAX_EXT_CERTS) { 1247 error_f("too many %s constraints", ext_name); 1248 goto out; 1249 } 1250 *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1, 1251 sizeof(**certs)); 1252 if ((r = sshkey_froms(b, &k)) != 0) { 1253 error_fr(r, "parse key"); 1254 goto out; 1255 } 1256 (*certs)[(*ncerts)++] = k; 1257 } 1258 } else { 1259 error_f("unsupported constraint \"%s\"", ext_name); 1260 r = SSH_ERR_FEATURE_UNSUPPORTED; 1261 goto out; 1262 } 1263 /* success */ 1264 r = 0; 1265 out: 1266 free(ext_name); 1267 sshbuf_free(b); 1268 return r; 1269 } 1270 1271 static int 1272 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1273 u_int *secondsp, int *confirmp, char **sk_providerp, 1274 struct dest_constraint **dcsp, size_t *ndcsp, 1275 int *cert_onlyp, size_t *ncerts, struct sshkey ***certs) 1276 { 1277 u_char ctype; 1278 int r; 1279 u_int seconds, maxsign = 0; 1280 1281 while (sshbuf_len(m)) { 1282 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1283 error_fr(r, "parse constraint type"); 1284 goto out; 1285 } 1286 switch (ctype) { 1287 case SSH_AGENT_CONSTRAIN_LIFETIME: 1288 if (*deathp != 0) { 1289 error_f("lifetime already set"); 1290 r = SSH_ERR_INVALID_FORMAT; 1291 goto out; 1292 } 1293 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1294 error_fr(r, "parse lifetime constraint"); 1295 goto out; 1296 } 1297 *deathp = monotime() + seconds; 1298 *secondsp = seconds; 1299 break; 1300 case SSH_AGENT_CONSTRAIN_CONFIRM: 1301 if (*confirmp != 0) { 1302 error_f("confirm already set"); 1303 r = SSH_ERR_INVALID_FORMAT; 1304 goto out; 1305 } 1306 *confirmp = 1; 1307 break; 1308 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1309 if (k == NULL) { 1310 error_f("maxsign not valid here"); 1311 r = SSH_ERR_INVALID_FORMAT; 1312 goto out; 1313 } 1314 if (maxsign != 0) { 1315 error_f("maxsign already set"); 1316 r = SSH_ERR_INVALID_FORMAT; 1317 goto out; 1318 } 1319 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1320 error_fr(r, "parse maxsign constraint"); 1321 goto out; 1322 } 1323 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1324 error_fr(r, "enable maxsign"); 1325 goto out; 1326 } 1327 break; 1328 case SSH_AGENT_CONSTRAIN_EXTENSION: 1329 if ((r = parse_key_constraint_extension(m, 1330 sk_providerp, dcsp, ndcsp, 1331 cert_onlyp, certs, ncerts)) != 0) 1332 goto out; /* error already logged */ 1333 break; 1334 default: 1335 error_f("Unknown constraint %d", ctype); 1336 r = SSH_ERR_FEATURE_UNSUPPORTED; 1337 goto out; 1338 } 1339 } 1340 /* success */ 1341 r = 0; 1342 out: 1343 return r; 1344 } 1345 1346 static void 1347 process_add_identity(SocketEntry *e) 1348 { 1349 Identity *id; 1350 int success = 0, confirm = 0; 1351 char *fp, *comment = NULL, *sk_provider = NULL; 1352 char canonical_provider[PATH_MAX]; 1353 time_t death = 0; 1354 u_int seconds = 0; 1355 struct dest_constraint *dest_constraints = NULL; 1356 size_t ndest_constraints = 0; 1357 struct sshkey *k = NULL; 1358 int r = SSH_ERR_INTERNAL_ERROR; 1359 1360 debug2_f("entering"); 1361 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1362 k == NULL || 1363 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1364 error_fr(r, "parse"); 1365 goto out; 1366 } 1367 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1368 &sk_provider, &dest_constraints, &ndest_constraints, 1369 NULL, NULL, NULL) != 0) { 1370 error_f("failed to parse constraints"); 1371 sshbuf_reset(e->request); 1372 goto out; 1373 } 1374 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1375 1376 if (sk_provider != NULL) { 1377 if (!sshkey_is_sk(k)) { 1378 error("Cannot add provider: %s is not an " 1379 "authenticator-hosted key", sshkey_type(k)); 1380 goto out; 1381 } 1382 if (strcasecmp(sk_provider, "internal") == 0) { 1383 debug_f("internal provider"); 1384 } else { 1385 if (socket_is_remote(e) && !remote_add_provider) { 1386 verbose("failed add of SK provider \"%.100s\": " 1387 "remote addition of providers is disabled", 1388 sk_provider); 1389 goto out; 1390 } 1391 if (realpath(sk_provider, canonical_provider) == NULL) { 1392 verbose("failed provider \"%.100s\": " 1393 "realpath: %s", sk_provider, 1394 strerror(errno)); 1395 goto out; 1396 } 1397 free(sk_provider); 1398 sk_provider = xstrdup(canonical_provider); 1399 if (match_pattern_list(sk_provider, 1400 allowed_providers, 0) != 1) { 1401 error("Refusing add key: " 1402 "provider %s not allowed", sk_provider); 1403 goto out; 1404 } 1405 } 1406 } 1407 if ((r = sshkey_shield_private(k)) != 0) { 1408 error_fr(r, "shield private"); 1409 goto out; 1410 } 1411 if (lifetime && !death) 1412 death = monotime() + lifetime; 1413 if ((id = lookup_identity(k)) == NULL) { 1414 id = xcalloc(1, sizeof(Identity)); 1415 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1416 /* Increment the number of identities. */ 1417 idtab->nentries++; 1418 } else { 1419 /* identity not visible, do not update */ 1420 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1421 goto out; /* error already logged */ 1422 /* key state might have been updated */ 1423 sshkey_free(id->key); 1424 free(id->comment); 1425 free(id->sk_provider); 1426 free_dest_constraints(id->dest_constraints, 1427 id->ndest_constraints); 1428 } 1429 /* success */ 1430 id->key = k; 1431 id->comment = comment; 1432 id->death = death; 1433 id->confirm = confirm; 1434 id->sk_provider = sk_provider; 1435 id->dest_constraints = dest_constraints; 1436 id->ndest_constraints = ndest_constraints; 1437 1438 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1439 SSH_FP_DEFAULT)) == NULL) 1440 fatal_f("sshkey_fingerprint failed"); 1441 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1442 "(provider: %s) (destination constraints: %zu)", 1443 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1444 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1445 free(fp); 1446 /* transferred */ 1447 k = NULL; 1448 comment = NULL; 1449 sk_provider = NULL; 1450 dest_constraints = NULL; 1451 ndest_constraints = 0; 1452 success = 1; 1453 out: 1454 free(sk_provider); 1455 free(comment); 1456 sshkey_free(k); 1457 free_dest_constraints(dest_constraints, ndest_constraints); 1458 send_status(e, success); 1459 } 1460 1461 /* XXX todo: encrypt sensitive data with passphrase */ 1462 static void 1463 process_lock_agent(SocketEntry *e, int lock) 1464 { 1465 int r, success = 0, delay; 1466 char *passwd; 1467 u_char passwdhash[LOCK_SIZE]; 1468 static u_int fail_count = 0; 1469 size_t pwlen; 1470 1471 debug2_f("entering"); 1472 /* 1473 * This is deliberately fatal: the user has requested that we lock, 1474 * but we can't parse their request properly. The only safe thing to 1475 * do is abort. 1476 */ 1477 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1478 fatal_fr(r, "parse"); 1479 if (pwlen == 0) { 1480 debug("empty password not supported"); 1481 } else if (locked && !lock) { 1482 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1483 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1484 fatal("bcrypt_pbkdf"); 1485 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1486 debug("agent unlocked"); 1487 locked = 0; 1488 fail_count = 0; 1489 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1490 success = 1; 1491 } else { 1492 /* delay in 0.1s increments up to 10s */ 1493 if (fail_count < 100) 1494 fail_count++; 1495 delay = 100000 * fail_count; 1496 debug("unlock failed, delaying %0.1lf seconds", 1497 (double)delay/1000000); 1498 usleep(delay); 1499 } 1500 explicit_bzero(passwdhash, sizeof(passwdhash)); 1501 } else if (!locked && lock) { 1502 debug("agent locked"); 1503 locked = 1; 1504 arc4random_buf(lock_salt, sizeof(lock_salt)); 1505 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1506 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1507 fatal("bcrypt_pbkdf"); 1508 success = 1; 1509 } 1510 freezero(passwd, pwlen); 1511 send_status(e, success); 1512 } 1513 1514 static void 1515 no_identities(SocketEntry *e) 1516 { 1517 struct sshbuf *msg; 1518 int r; 1519 1520 if ((msg = sshbuf_new()) == NULL) 1521 fatal_f("sshbuf_new failed"); 1522 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1523 (r = sshbuf_put_u32(msg, 0)) != 0 || 1524 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1525 fatal_fr(r, "compose"); 1526 sshbuf_free(msg); 1527 } 1528 1529 #ifdef ENABLE_PKCS11 1530 /* Add an identity to idlist; takes ownership of 'key' and 'comment' */ 1531 static void 1532 add_p11_identity(struct sshkey *key, char *comment, const char *provider, 1533 time_t death, u_int confirm, struct dest_constraint *dest_constraints, 1534 size_t ndest_constraints) 1535 { 1536 Identity *id; 1537 1538 if (lookup_identity(key) != NULL) { 1539 sshkey_free(key); 1540 free(comment); 1541 return; 1542 } 1543 id = xcalloc(1, sizeof(Identity)); 1544 id->key = key; 1545 id->comment = comment; 1546 id->provider = xstrdup(provider); 1547 id->death = death; 1548 id->confirm = confirm; 1549 id->dest_constraints = dup_dest_constraints(dest_constraints, 1550 ndest_constraints); 1551 id->ndest_constraints = ndest_constraints; 1552 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1553 idtab->nentries++; 1554 } 1555 1556 static void 1557 process_add_smartcard_key(SocketEntry *e) 1558 { 1559 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1560 char **comments = NULL; 1561 int r, i, count = 0, success = 0, confirm = 0; 1562 u_int seconds = 0; 1563 time_t death = 0; 1564 struct sshkey **keys = NULL, *k; 1565 struct dest_constraint *dest_constraints = NULL; 1566 size_t j, ndest_constraints = 0, ncerts = 0; 1567 struct sshkey **certs = NULL; 1568 int cert_only = 0; 1569 1570 debug2_f("entering"); 1571 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1572 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1573 error_fr(r, "parse"); 1574 goto send; 1575 } 1576 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1577 NULL, &dest_constraints, &ndest_constraints, &cert_only, 1578 &ncerts, &certs) != 0) { 1579 error_f("failed to parse constraints"); 1580 goto send; 1581 } 1582 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1583 if (socket_is_remote(e) && !remote_add_provider) { 1584 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1585 "providers is disabled", provider); 1586 goto send; 1587 } 1588 if (realpath(provider, canonical_provider) == NULL) { 1589 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1590 provider, strerror(errno)); 1591 goto send; 1592 } 1593 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1594 verbose("refusing PKCS#11 add of \"%.100s\": " 1595 "provider not allowed", canonical_provider); 1596 goto send; 1597 } 1598 debug_f("add %.100s", canonical_provider); 1599 if (lifetime && !death) 1600 death = monotime() + lifetime; 1601 1602 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1603 for (i = 0; i < count; i++) { 1604 if (comments[i] == NULL || comments[i][0] == '\0') { 1605 free(comments[i]); 1606 comments[i] = xstrdup(canonical_provider); 1607 } 1608 for (j = 0; j < ncerts; j++) { 1609 if (!sshkey_is_cert(certs[j])) 1610 continue; 1611 if (!sshkey_equal_public(keys[i], certs[j])) 1612 continue; 1613 if (pkcs11_make_cert(keys[i], certs[j], &k) != 0) 1614 continue; 1615 add_p11_identity(k, xstrdup(comments[i]), 1616 canonical_provider, death, confirm, 1617 dest_constraints, ndest_constraints); 1618 success = 1; 1619 } 1620 if (!cert_only && lookup_identity(keys[i]) == NULL) { 1621 add_p11_identity(keys[i], comments[i], 1622 canonical_provider, death, confirm, 1623 dest_constraints, ndest_constraints); 1624 keys[i] = NULL; /* transferred */ 1625 comments[i] = NULL; /* transferred */ 1626 success = 1; 1627 } 1628 /* XXX update constraints for existing keys */ 1629 sshkey_free(keys[i]); 1630 free(comments[i]); 1631 } 1632 send: 1633 free(pin); 1634 free(provider); 1635 free(keys); 1636 free(comments); 1637 free_dest_constraints(dest_constraints, ndest_constraints); 1638 for (j = 0; j < ncerts; j++) 1639 sshkey_free(certs[j]); 1640 free(certs); 1641 send_status(e, success); 1642 } 1643 1644 static void 1645 process_remove_smartcard_key(SocketEntry *e) 1646 { 1647 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1648 int r, success = 0; 1649 Identity *id, *nxt; 1650 1651 debug2_f("entering"); 1652 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1653 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1654 error_fr(r, "parse"); 1655 goto send; 1656 } 1657 free(pin); 1658 1659 if (realpath(provider, canonical_provider) == NULL) { 1660 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1661 provider, strerror(errno)); 1662 goto send; 1663 } 1664 1665 debug_f("remove %.100s", canonical_provider); 1666 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1667 nxt = TAILQ_NEXT(id, next); 1668 /* Skip file--based keys */ 1669 if (id->provider == NULL) 1670 continue; 1671 if (!strcmp(canonical_provider, id->provider)) { 1672 TAILQ_REMOVE(&idtab->idlist, id, next); 1673 free_identity(id); 1674 idtab->nentries--; 1675 } 1676 } 1677 if (pkcs11_del_provider(canonical_provider) == 0) 1678 success = 1; 1679 else 1680 error_f("pkcs11_del_provider failed"); 1681 send: 1682 free(provider); 1683 send_status(e, success); 1684 } 1685 #endif /* ENABLE_PKCS11 */ 1686 1687 static int 1688 process_ext_session_bind(SocketEntry *e) 1689 { 1690 int r, sid_match, key_match; 1691 struct sshkey *key = NULL; 1692 struct sshbuf *sid = NULL, *sig = NULL; 1693 char *fp = NULL; 1694 size_t i; 1695 u_char fwd = 0; 1696 1697 debug2_f("entering"); 1698 e->session_bind_attempted = 1; 1699 if ((r = sshkey_froms(e->request, &key)) != 0 || 1700 (r = sshbuf_froms(e->request, &sid)) != 0 || 1701 (r = sshbuf_froms(e->request, &sig)) != 0 || 1702 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1703 error_fr(r, "parse"); 1704 goto out; 1705 } 1706 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1707 SSH_FP_DEFAULT)) == NULL) 1708 fatal_f("fingerprint failed"); 1709 /* check signature with hostkey on session ID */ 1710 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1711 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1712 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1713 goto out; 1714 } 1715 /* check whether sid/key already recorded */ 1716 for (i = 0; i < e->nsession_ids; i++) { 1717 if (!e->session_ids[i].forwarded) { 1718 error_f("attempt to bind session ID to socket " 1719 "previously bound for authentication attempt"); 1720 r = -1; 1721 goto out; 1722 } 1723 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1724 key_match = sshkey_equal(key, e->session_ids[i].key); 1725 if (sid_match && key_match) { 1726 debug_f("session ID already recorded for %s %s", 1727 sshkey_type(key), fp); 1728 r = 0; 1729 goto out; 1730 } else if (sid_match) { 1731 error_f("session ID recorded against different key " 1732 "for %s %s", sshkey_type(key), fp); 1733 r = -1; 1734 goto out; 1735 } 1736 /* 1737 * new sid with previously-seen key can happen, e.g. multiple 1738 * connections to the same host. 1739 */ 1740 } 1741 /* record new key/sid */ 1742 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1743 error_f("too many session IDs recorded"); 1744 goto out; 1745 } 1746 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1747 e->nsession_ids + 1, sizeof(*e->session_ids)); 1748 i = e->nsession_ids++; 1749 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1750 AGENT_MAX_SESSION_IDS); 1751 e->session_ids[i].key = key; 1752 e->session_ids[i].forwarded = fwd != 0; 1753 key = NULL; /* transferred */ 1754 /* can't transfer sid; it's refcounted and scoped to request's life */ 1755 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1756 fatal_f("sshbuf_new"); 1757 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1758 fatal_fr(r, "sshbuf_putb session ID"); 1759 /* success */ 1760 r = 0; 1761 out: 1762 free(fp); 1763 sshkey_free(key); 1764 sshbuf_free(sid); 1765 sshbuf_free(sig); 1766 return r == 0 ? 1 : 0; 1767 } 1768 1769 static void 1770 process_extension(SocketEntry *e) 1771 { 1772 int r, success = 0; 1773 char *name; 1774 1775 debug2_f("entering"); 1776 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1777 error_fr(r, "parse"); 1778 goto send; 1779 } 1780 if (strcmp(name, "session-bind@openssh.com") == 0) 1781 success = process_ext_session_bind(e); 1782 else 1783 debug_f("unsupported extension \"%s\"", name); 1784 free(name); 1785 send: 1786 send_status(e, success); 1787 } 1788 /* 1789 * dispatch incoming message. 1790 * returns 1 on success, 0 for incomplete messages or -1 on error. 1791 */ 1792 static int 1793 process_message(u_int socknum) 1794 { 1795 u_int msg_len; 1796 u_char type; 1797 const u_char *cp; 1798 int r; 1799 SocketEntry *e; 1800 1801 if (socknum >= sockets_alloc) 1802 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1803 e = &sockets[socknum]; 1804 1805 if (sshbuf_len(e->input) < 5) 1806 return 0; /* Incomplete message header. */ 1807 cp = sshbuf_ptr(e->input); 1808 msg_len = PEEK_U32(cp); 1809 if (msg_len > AGENT_MAX_LEN) { 1810 debug_f("socket %u (fd=%d) message too long %u > %u", 1811 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1812 return -1; 1813 } 1814 if (sshbuf_len(e->input) < msg_len + 4) 1815 return 0; /* Incomplete message body. */ 1816 1817 /* move the current input to e->request */ 1818 sshbuf_reset(e->request); 1819 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1820 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1821 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1822 r == SSH_ERR_STRING_TOO_LARGE) { 1823 error_fr(r, "parse"); 1824 return -1; 1825 } 1826 fatal_fr(r, "parse"); 1827 } 1828 1829 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1830 1831 /* check whether agent is locked */ 1832 if (locked && type != SSH_AGENTC_UNLOCK) { 1833 sshbuf_reset(e->request); 1834 switch (type) { 1835 case SSH2_AGENTC_REQUEST_IDENTITIES: 1836 /* send empty lists */ 1837 no_identities(e); 1838 break; 1839 default: 1840 /* send a fail message for all other request types */ 1841 send_status(e, 0); 1842 } 1843 return 1; 1844 } 1845 1846 switch (type) { 1847 case SSH_AGENTC_LOCK: 1848 case SSH_AGENTC_UNLOCK: 1849 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1850 break; 1851 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1852 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1853 break; 1854 /* ssh2 */ 1855 case SSH2_AGENTC_SIGN_REQUEST: 1856 process_sign_request2(e); 1857 break; 1858 case SSH2_AGENTC_REQUEST_IDENTITIES: 1859 process_request_identities(e); 1860 break; 1861 case SSH2_AGENTC_ADD_IDENTITY: 1862 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1863 process_add_identity(e); 1864 break; 1865 case SSH2_AGENTC_REMOVE_IDENTITY: 1866 process_remove_identity(e); 1867 break; 1868 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1869 process_remove_all_identities(e); 1870 break; 1871 #ifdef ENABLE_PKCS11 1872 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1873 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1874 process_add_smartcard_key(e); 1875 break; 1876 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1877 process_remove_smartcard_key(e); 1878 break; 1879 #endif /* ENABLE_PKCS11 */ 1880 case SSH_AGENTC_EXTENSION: 1881 process_extension(e); 1882 break; 1883 default: 1884 /* Unknown message. Respond with failure. */ 1885 error("Unknown message %d", type); 1886 sshbuf_reset(e->request); 1887 send_status(e, 0); 1888 break; 1889 } 1890 return 1; 1891 } 1892 1893 static void 1894 new_socket(sock_type type, int fd) 1895 { 1896 u_int i, old_alloc, new_alloc; 1897 1898 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1899 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1900 set_nonblock(fd); 1901 1902 if (fd > max_fd) 1903 max_fd = fd; 1904 1905 for (i = 0; i < sockets_alloc; i++) 1906 if (sockets[i].type == AUTH_UNUSED) { 1907 sockets[i].fd = fd; 1908 if ((sockets[i].input = sshbuf_new()) == NULL || 1909 (sockets[i].output = sshbuf_new()) == NULL || 1910 (sockets[i].request = sshbuf_new()) == NULL) 1911 fatal_f("sshbuf_new failed"); 1912 sockets[i].type = type; 1913 return; 1914 } 1915 old_alloc = sockets_alloc; 1916 new_alloc = sockets_alloc + 10; 1917 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1918 sizeof(sockets[0])); 1919 for (i = old_alloc; i < new_alloc; i++) 1920 sockets[i].type = AUTH_UNUSED; 1921 sockets_alloc = new_alloc; 1922 sockets[old_alloc].fd = fd; 1923 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1924 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1925 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1926 fatal_f("sshbuf_new failed"); 1927 sockets[old_alloc].type = type; 1928 } 1929 1930 static int 1931 handle_socket_read(u_int socknum) 1932 { 1933 struct sockaddr_un sunaddr; 1934 socklen_t slen; 1935 uid_t euid; 1936 gid_t egid; 1937 int fd; 1938 1939 slen = sizeof(sunaddr); 1940 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1941 if (fd == -1) { 1942 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1943 return -1; 1944 } 1945 if (getpeereid(fd, &euid, &egid) == -1) { 1946 error("getpeereid %d failed: %s", fd, strerror(errno)); 1947 close(fd); 1948 return -1; 1949 } 1950 if ((euid != 0) && (getuid() != euid)) { 1951 error("uid mismatch: peer euid %u != uid %u", 1952 (u_int) euid, (u_int) getuid()); 1953 close(fd); 1954 return -1; 1955 } 1956 new_socket(AUTH_CONNECTION, fd); 1957 return 0; 1958 } 1959 1960 static int 1961 handle_conn_read(u_int socknum) 1962 { 1963 char buf[AGENT_RBUF_LEN]; 1964 ssize_t len; 1965 int r; 1966 1967 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1968 if (len == -1) { 1969 if (errno == EAGAIN || errno == EINTR) 1970 return 0; 1971 error_f("read error on socket %u (fd %d): %s", 1972 socknum, sockets[socknum].fd, strerror(errno)); 1973 } 1974 return -1; 1975 } 1976 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1977 fatal_fr(r, "compose"); 1978 explicit_bzero(buf, sizeof(buf)); 1979 for (;;) { 1980 if ((r = process_message(socknum)) == -1) 1981 return -1; 1982 else if (r == 0) 1983 break; 1984 } 1985 return 0; 1986 } 1987 1988 static int 1989 handle_conn_write(u_int socknum) 1990 { 1991 ssize_t len; 1992 int r; 1993 1994 if (sshbuf_len(sockets[socknum].output) == 0) 1995 return 0; /* shouldn't happen */ 1996 if ((len = write(sockets[socknum].fd, 1997 sshbuf_ptr(sockets[socknum].output), 1998 sshbuf_len(sockets[socknum].output))) <= 0) { 1999 if (len == -1) { 2000 if (errno == EAGAIN || errno == EINTR) 2001 return 0; 2002 error_f("read error on socket %u (fd %d): %s", 2003 socknum, sockets[socknum].fd, strerror(errno)); 2004 } 2005 return -1; 2006 } 2007 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 2008 fatal_fr(r, "consume"); 2009 return 0; 2010 } 2011 2012 static void 2013 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 2014 { 2015 size_t i; 2016 u_int socknum, activefds = npfd; 2017 2018 for (i = 0; i < npfd; i++) { 2019 if (pfd[i].revents == 0) 2020 continue; 2021 /* Find sockets entry */ 2022 for (socknum = 0; socknum < sockets_alloc; socknum++) { 2023 if (sockets[socknum].type != AUTH_SOCKET && 2024 sockets[socknum].type != AUTH_CONNECTION) 2025 continue; 2026 if (pfd[i].fd == sockets[socknum].fd) 2027 break; 2028 } 2029 if (socknum >= sockets_alloc) { 2030 error_f("no socket for fd %d", pfd[i].fd); 2031 continue; 2032 } 2033 /* Process events */ 2034 switch (sockets[socknum].type) { 2035 case AUTH_SOCKET: 2036 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 2037 break; 2038 if (npfd > maxfds) { 2039 debug3("out of fds (active %u >= limit %u); " 2040 "skipping accept", activefds, maxfds); 2041 break; 2042 } 2043 if (handle_socket_read(socknum) == 0) 2044 activefds++; 2045 break; 2046 case AUTH_CONNECTION: 2047 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 2048 handle_conn_read(socknum) != 0) 2049 goto close_sock; 2050 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 2051 handle_conn_write(socknum) != 0) { 2052 close_sock: 2053 if (activefds == 0) 2054 fatal("activefds == 0 at close_sock"); 2055 close_socket(&sockets[socknum]); 2056 activefds--; 2057 break; 2058 } 2059 break; 2060 default: 2061 break; 2062 } 2063 } 2064 } 2065 2066 static int 2067 prepare_poll(struct pollfd **pfdp, size_t *npfdp, struct timespec *timeoutp, u_int maxfds) 2068 { 2069 struct pollfd *pfd = *pfdp; 2070 size_t i, j, npfd = 0; 2071 time_t deadline; 2072 int r; 2073 2074 /* Count active sockets */ 2075 for (i = 0; i < sockets_alloc; i++) { 2076 switch (sockets[i].type) { 2077 case AUTH_SOCKET: 2078 case AUTH_CONNECTION: 2079 npfd++; 2080 break; 2081 case AUTH_UNUSED: 2082 break; 2083 default: 2084 fatal("Unknown socket type %d", sockets[i].type); 2085 break; 2086 } 2087 } 2088 if (npfd != *npfdp && 2089 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 2090 fatal_f("recallocarray failed"); 2091 *pfdp = pfd; 2092 *npfdp = npfd; 2093 2094 for (i = j = 0; i < sockets_alloc; i++) { 2095 switch (sockets[i].type) { 2096 case AUTH_SOCKET: 2097 if (npfd > maxfds) { 2098 debug3("out of fds (active %zu >= limit %u); " 2099 "skipping arming listener", npfd, maxfds); 2100 break; 2101 } 2102 pfd[j].fd = sockets[i].fd; 2103 pfd[j].revents = 0; 2104 pfd[j].events = POLLIN; 2105 j++; 2106 break; 2107 case AUTH_CONNECTION: 2108 pfd[j].fd = sockets[i].fd; 2109 pfd[j].revents = 0; 2110 /* 2111 * Only prepare to read if we can handle a full-size 2112 * input read buffer and enqueue a max size reply.. 2113 */ 2114 if ((r = sshbuf_check_reserve(sockets[i].input, 2115 AGENT_RBUF_LEN)) == 0 && 2116 (r = sshbuf_check_reserve(sockets[i].output, 2117 AGENT_MAX_LEN)) == 0) 2118 pfd[j].events = POLLIN; 2119 else if (r != SSH_ERR_NO_BUFFER_SPACE) 2120 fatal_fr(r, "reserve"); 2121 if (sshbuf_len(sockets[i].output) > 0) 2122 pfd[j].events |= POLLOUT; 2123 j++; 2124 break; 2125 default: 2126 break; 2127 } 2128 } 2129 deadline = reaper(); 2130 if (parent_alive_interval != 0) 2131 deadline = (deadline == 0) ? parent_alive_interval : 2132 MINIMUM(deadline, parent_alive_interval); 2133 if (deadline != 0) 2134 ptimeout_deadline_sec(timeoutp, deadline); 2135 return (1); 2136 } 2137 2138 static void 2139 cleanup_socket(void) 2140 { 2141 if (cleanup_pid != 0 && getpid() != cleanup_pid) 2142 return; 2143 debug_f("cleanup"); 2144 if (socket_name[0]) 2145 unlink(socket_name); 2146 if (socket_dir[0]) 2147 rmdir(socket_dir); 2148 } 2149 2150 void 2151 cleanup_exit(int i) 2152 { 2153 cleanup_socket(); 2154 #ifdef ENABLE_PKCS11 2155 pkcs11_terminate(); 2156 #endif 2157 _exit(i); 2158 } 2159 2160 static void 2161 cleanup_handler(int sig) 2162 { 2163 signalled = sig; 2164 } 2165 2166 static void 2167 check_parent_exists(void) 2168 { 2169 /* 2170 * If our parent has exited then getppid() will return (pid_t)1, 2171 * so testing for that should be safe. 2172 */ 2173 if (parent_pid != -1 && getppid() != parent_pid) { 2174 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2175 cleanup_socket(); 2176 _exit(2); 2177 } 2178 } 2179 2180 static void 2181 usage(void) 2182 { 2183 fprintf(stderr, 2184 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" 2185 " [-O option] [-P allowed_providers] [-t life]\n" 2186 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2187 " [-P allowed_providers] [-t life] command [arg ...]\n" 2188 " ssh-agent [-c | -s] -k\n"); 2189 exit(1); 2190 } 2191 2192 int 2193 main(int ac, char **av) 2194 { 2195 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2196 int sock, ch, result, saved_errno; 2197 char *shell, *format, *pidstr, *agentsocket = NULL; 2198 #ifdef HAVE_SETRLIMIT 2199 struct rlimit rlim; 2200 #endif 2201 extern int optind; 2202 extern char *optarg; 2203 pid_t pid; 2204 char pidstrbuf[1 + 3 * sizeof pid]; 2205 size_t len; 2206 mode_t prev_mask; 2207 struct timespec timeout; 2208 struct pollfd *pfd = NULL; 2209 size_t npfd = 0; 2210 u_int maxfds; 2211 sigset_t nsigset, osigset; 2212 2213 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2214 sanitise_stdfd(); 2215 2216 /* drop */ 2217 (void)setegid(getgid()); 2218 (void)setgid(getgid()); 2219 2220 platform_disable_tracing(0); /* strict=no */ 2221 2222 #ifdef RLIMIT_NOFILE 2223 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2224 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2225 #endif 2226 2227 __progname = ssh_get_progname(av[0]); 2228 seed_rng(); 2229 2230 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { 2231 switch (ch) { 2232 case 'E': 2233 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2234 if (fingerprint_hash == -1) 2235 fatal("Invalid hash algorithm \"%s\"", optarg); 2236 break; 2237 case 'c': 2238 if (s_flag) 2239 usage(); 2240 c_flag++; 2241 break; 2242 case 'k': 2243 k_flag++; 2244 break; 2245 case 'O': 2246 if (strcmp(optarg, "no-restrict-websafe") == 0) 2247 restrict_websafe = 0; 2248 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2249 remote_add_provider = 1; 2250 else 2251 fatal("Unknown -O option"); 2252 break; 2253 case 'P': 2254 if (allowed_providers != NULL) 2255 fatal("-P option already specified"); 2256 allowed_providers = xstrdup(optarg); 2257 break; 2258 case 's': 2259 if (c_flag) 2260 usage(); 2261 s_flag++; 2262 break; 2263 case 'd': 2264 if (d_flag || D_flag) 2265 usage(); 2266 d_flag++; 2267 break; 2268 case 'D': 2269 if (d_flag || D_flag) 2270 usage(); 2271 D_flag++; 2272 break; 2273 case 'a': 2274 agentsocket = optarg; 2275 break; 2276 case 't': 2277 if ((lifetime = convtime(optarg)) == -1) { 2278 fprintf(stderr, "Invalid lifetime\n"); 2279 usage(); 2280 } 2281 break; 2282 default: 2283 usage(); 2284 } 2285 } 2286 ac -= optind; 2287 av += optind; 2288 2289 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2290 usage(); 2291 2292 if (allowed_providers == NULL) 2293 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2294 2295 if (ac == 0 && !c_flag && !s_flag) { 2296 shell = getenv("SHELL"); 2297 if (shell != NULL && (len = strlen(shell)) > 2 && 2298 strncmp(shell + len - 3, "csh", 3) == 0) 2299 c_flag = 1; 2300 } 2301 if (k_flag) { 2302 const char *errstr = NULL; 2303 2304 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2305 if (pidstr == NULL) { 2306 fprintf(stderr, "%s not set, cannot kill agent\n", 2307 SSH_AGENTPID_ENV_NAME); 2308 exit(1); 2309 } 2310 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2311 if (errstr) { 2312 fprintf(stderr, 2313 "%s=\"%s\", which is not a good PID: %s\n", 2314 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2315 exit(1); 2316 } 2317 if (kill(pid, SIGTERM) == -1) { 2318 perror("kill"); 2319 exit(1); 2320 } 2321 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2322 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2323 printf(format, SSH_AGENTPID_ENV_NAME); 2324 printf("echo Agent pid %ld killed;\n", (long)pid); 2325 exit(0); 2326 } 2327 2328 /* 2329 * Minimum file descriptors: 2330 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2331 * a few spare for libc / stack protectors / sanitisers, etc. 2332 */ 2333 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2334 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2335 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2336 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2337 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2338 2339 parent_pid = getpid(); 2340 2341 if (agentsocket == NULL) { 2342 /* Create private directory for agent socket */ 2343 mktemp_proto(socket_dir, sizeof(socket_dir)); 2344 if (mkdtemp(socket_dir) == NULL) { 2345 perror("mkdtemp: private socket dir"); 2346 exit(1); 2347 } 2348 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2349 (long)parent_pid); 2350 } else { 2351 /* Try to use specified agent socket */ 2352 socket_dir[0] = '\0'; 2353 strlcpy(socket_name, agentsocket, sizeof socket_name); 2354 } 2355 2356 /* 2357 * Create socket early so it will exist before command gets run from 2358 * the parent. 2359 */ 2360 prev_mask = umask(0177); 2361 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2362 if (sock < 0) { 2363 /* XXX - unix_listener() calls error() not perror() */ 2364 *socket_name = '\0'; /* Don't unlink any existing file */ 2365 cleanup_exit(1); 2366 } 2367 umask(prev_mask); 2368 2369 /* 2370 * Fork, and have the parent execute the command, if any, or present 2371 * the socket data. The child continues as the authentication agent. 2372 */ 2373 if (D_flag || d_flag) { 2374 log_init(__progname, 2375 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2376 SYSLOG_FACILITY_AUTH, 1); 2377 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2378 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2379 SSH_AUTHSOCKET_ENV_NAME); 2380 printf("echo Agent pid %ld;\n", (long)parent_pid); 2381 fflush(stdout); 2382 goto skip; 2383 } 2384 pid = fork(); 2385 if (pid == -1) { 2386 perror("fork"); 2387 cleanup_exit(1); 2388 } 2389 if (pid != 0) { /* Parent - execute the given command. */ 2390 close(sock); 2391 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2392 if (ac == 0) { 2393 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2394 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2395 SSH_AUTHSOCKET_ENV_NAME); 2396 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2397 SSH_AGENTPID_ENV_NAME); 2398 printf("echo Agent pid %ld;\n", (long)pid); 2399 exit(0); 2400 } 2401 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2402 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2403 perror("setenv"); 2404 exit(1); 2405 } 2406 execvp(av[0], av); 2407 perror(av[0]); 2408 exit(1); 2409 } 2410 /* child */ 2411 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2412 2413 if (setsid() == -1) { 2414 error("setsid: %s", strerror(errno)); 2415 cleanup_exit(1); 2416 } 2417 2418 (void)chdir("/"); 2419 if (stdfd_devnull(1, 1, 1) == -1) 2420 error_f("stdfd_devnull failed"); 2421 2422 #ifdef HAVE_SETRLIMIT 2423 /* deny core dumps, since memory contains unencrypted private keys */ 2424 rlim.rlim_cur = rlim.rlim_max = 0; 2425 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2426 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2427 cleanup_exit(1); 2428 } 2429 #endif 2430 2431 skip: 2432 2433 cleanup_pid = getpid(); 2434 2435 #ifdef ENABLE_PKCS11 2436 pkcs11_init(0); 2437 #endif 2438 new_socket(AUTH_SOCKET, sock); 2439 if (ac > 0) 2440 parent_alive_interval = 10; 2441 idtab_init(); 2442 ssh_signal(SIGPIPE, SIG_IGN); 2443 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2444 ssh_signal(SIGHUP, cleanup_handler); 2445 ssh_signal(SIGTERM, cleanup_handler); 2446 2447 sigemptyset(&nsigset); 2448 sigaddset(&nsigset, SIGINT); 2449 sigaddset(&nsigset, SIGHUP); 2450 sigaddset(&nsigset, SIGTERM); 2451 2452 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2453 fatal("%s: pledge: %s", __progname, strerror(errno)); 2454 platform_pledge_agent(); 2455 2456 while (1) { 2457 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 2458 if (signalled != 0) { 2459 logit("exiting on signal %d", (int)signalled); 2460 cleanup_exit(2); 2461 } 2462 ptimeout_init(&timeout); 2463 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2464 result = ppoll(pfd, npfd, ptimeout_get_tsp(&timeout), &osigset); 2465 sigprocmask(SIG_SETMASK, &osigset, NULL); 2466 saved_errno = errno; 2467 if (parent_alive_interval != 0) 2468 check_parent_exists(); 2469 (void) reaper(); /* remove expired keys */ 2470 if (result == -1) { 2471 if (saved_errno == EINTR) 2472 continue; 2473 fatal("poll: %s", strerror(saved_errno)); 2474 } else if (result > 0) 2475 after_poll(pfd, npfd, maxfds); 2476 } 2477 /* NOTREACHED */ 2478 } 2479