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 /* 202 * Client connection count; incremented in new_socket() and decremented in 203 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 204 * normally initialized to 1, it will never reach 0. However, if the -x 205 * option is specified, it is initialized to 0 in main(); in that case, 206 * ssh-agent will exit as soon as it has had at least one client but no 207 * longer has any. 208 */ 209 static int xcount = 1; 210 211 static void 212 close_socket(SocketEntry *e) 213 { 214 size_t i; 215 int last = 0; 216 217 if (e->type == AUTH_CONNECTION) { 218 debug("xcount %d -> %d", xcount, xcount - 1); 219 if (--xcount == 0) 220 last = 1; 221 } 222 close(e->fd); 223 sshbuf_free(e->input); 224 sshbuf_free(e->output); 225 sshbuf_free(e->request); 226 for (i = 0; i < e->nsession_ids; i++) { 227 sshkey_free(e->session_ids[i].key); 228 sshbuf_free(e->session_ids[i].sid); 229 } 230 free(e->session_ids); 231 memset(e, '\0', sizeof(*e)); 232 e->fd = -1; 233 e->type = AUTH_UNUSED; 234 if (last) 235 cleanup_exit(0); 236 } 237 238 static void 239 idtab_init(void) 240 { 241 idtab = xcalloc(1, sizeof(*idtab)); 242 TAILQ_INIT(&idtab->idlist); 243 idtab->nentries = 0; 244 } 245 246 static void 247 free_dest_constraint_hop(struct dest_constraint_hop *dch) 248 { 249 u_int i; 250 251 if (dch == NULL) 252 return; 253 free(dch->user); 254 free(dch->hostname); 255 for (i = 0; i < dch->nkeys; i++) 256 sshkey_free(dch->keys[i]); 257 free(dch->keys); 258 free(dch->key_is_ca); 259 } 260 261 static void 262 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 263 { 264 size_t i; 265 266 for (i = 0; i < ndcs; i++) { 267 free_dest_constraint_hop(&dcs[i].from); 268 free_dest_constraint_hop(&dcs[i].to); 269 } 270 free(dcs); 271 } 272 273 #ifdef ENABLE_PKCS11 274 static void 275 dup_dest_constraint_hop(const struct dest_constraint_hop *dch, 276 struct dest_constraint_hop *out) 277 { 278 u_int i; 279 int r; 280 281 out->user = dch->user == NULL ? NULL : xstrdup(dch->user); 282 out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname); 283 out->is_ca = dch->is_ca; 284 out->nkeys = dch->nkeys; 285 out->keys = out->nkeys == 0 ? NULL : 286 xcalloc(out->nkeys, sizeof(*out->keys)); 287 out->key_is_ca = out->nkeys == 0 ? NULL : 288 xcalloc(out->nkeys, sizeof(*out->key_is_ca)); 289 for (i = 0; i < dch->nkeys; i++) { 290 if (dch->keys[i] != NULL && 291 (r = sshkey_from_private(dch->keys[i], 292 &(out->keys[i]))) != 0) 293 fatal_fr(r, "copy key"); 294 out->key_is_ca[i] = dch->key_is_ca[i]; 295 } 296 } 297 298 static struct dest_constraint * 299 dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs) 300 { 301 size_t i; 302 struct dest_constraint *ret; 303 304 if (ndcs == 0) 305 return NULL; 306 ret = xcalloc(ndcs, sizeof(*ret)); 307 for (i = 0; i < ndcs; i++) { 308 dup_dest_constraint_hop(&dcs[i].from, &ret[i].from); 309 dup_dest_constraint_hop(&dcs[i].to, &ret[i].to); 310 } 311 return ret; 312 } 313 #endif /* ENABLE_PKCS11 */ 314 315 #ifdef DEBUG_CONSTRAINTS 316 static void 317 dump_dest_constraint_hop(const struct dest_constraint_hop *dch) 318 { 319 u_int i; 320 char *fp; 321 322 debug_f("user %s hostname %s is_ca %d nkeys %u", 323 dch->user == NULL ? "(null)" : dch->user, 324 dch->hostname == NULL ? "(null)" : dch->hostname, 325 dch->is_ca, dch->nkeys); 326 for (i = 0; i < dch->nkeys; i++) { 327 fp = NULL; 328 if (dch->keys[i] != NULL && 329 (fp = sshkey_fingerprint(dch->keys[i], 330 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) 331 fatal_f("fingerprint failed"); 332 debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys, 333 dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]), 334 dch->keys[i] == NULL ? "" : " ", 335 dch->keys[i] == NULL ? "none" : fp, 336 dch->key_is_ca[i]); 337 free(fp); 338 } 339 } 340 #endif /* DEBUG_CONSTRAINTS */ 341 342 static void 343 dump_dest_constraints(const char *context, 344 const struct dest_constraint *dcs, size_t ndcs) 345 { 346 #ifdef DEBUG_CONSTRAINTS 347 size_t i; 348 349 debug_f("%s: %zu constraints", context, ndcs); 350 for (i = 0; i < ndcs; i++) { 351 debug_f("constraint %zu / %zu: from: ", i, ndcs); 352 dump_dest_constraint_hop(&dcs[i].from); 353 debug_f("constraint %zu / %zu: to: ", i, ndcs); 354 dump_dest_constraint_hop(&dcs[i].to); 355 } 356 debug_f("done for %s", context); 357 #endif /* DEBUG_CONSTRAINTS */ 358 } 359 360 static void 361 free_identity(Identity *id) 362 { 363 sshkey_free(id->key); 364 free(id->provider); 365 free(id->comment); 366 free(id->sk_provider); 367 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 368 free(id); 369 } 370 371 /* 372 * Match 'key' against the key/CA list in a destination constraint hop 373 * Returns 0 on success or -1 otherwise. 374 */ 375 static int 376 match_key_hop(const char *tag, const struct sshkey *key, 377 const struct dest_constraint_hop *dch) 378 { 379 const char *reason = NULL; 380 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 381 u_int i; 382 char *fp; 383 384 if (key == NULL) 385 return -1; 386 /* XXX logspam */ 387 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 388 SSH_FP_DEFAULT)) == NULL) 389 fatal_f("fingerprint failed"); 390 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 391 tag, hostname, sshkey_type(key), fp, dch->nkeys); 392 free(fp); 393 for (i = 0; i < dch->nkeys; i++) { 394 if (dch->keys[i] == NULL) 395 return -1; 396 /* XXX logspam */ 397 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 398 SSH_FP_DEFAULT)) == NULL) 399 fatal_f("fingerprint failed"); 400 debug3_f("%s: key %u: %s%s %s", tag, i, 401 dch->key_is_ca[i] ? "CA " : "", 402 sshkey_type(dch->keys[i]), fp); 403 free(fp); 404 if (!sshkey_is_cert(key)) { 405 /* plain key */ 406 if (dch->key_is_ca[i] || 407 !sshkey_equal(key, dch->keys[i])) 408 continue; 409 return 0; 410 } 411 /* certificate */ 412 if (!dch->key_is_ca[i]) 413 continue; 414 if (key->cert == NULL || key->cert->signature_key == NULL) 415 return -1; /* shouldn't happen */ 416 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 417 continue; 418 if (sshkey_cert_check_host(key, hostname, 1, 419 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 420 debug_f("cert %s / hostname %s rejected: %s", 421 key->cert->key_id, hostname, reason); 422 continue; 423 } 424 return 0; 425 } 426 return -1; 427 } 428 429 /* Check destination constraints on an identity against the hostkey/user */ 430 static int 431 permitted_by_dest_constraints(const struct sshkey *fromkey, 432 const struct sshkey *tokey, Identity *id, const char *user, 433 const char **hostnamep) 434 { 435 size_t i; 436 struct dest_constraint *d; 437 438 if (hostnamep != NULL) 439 *hostnamep = NULL; 440 for (i = 0; i < id->ndest_constraints; i++) { 441 d = id->dest_constraints + i; 442 /* XXX remove logspam */ 443 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 444 i, d->from.user ? d->from.user : "", 445 d->from.user ? "@" : "", 446 d->from.hostname ? d->from.hostname : "(ORIGIN)", 447 d->from.nkeys, 448 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 449 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 450 451 /* Match 'from' key */ 452 if (fromkey == NULL) { 453 /* We are matching the first hop */ 454 if (d->from.hostname != NULL || d->from.nkeys != 0) 455 continue; 456 } else if (match_key_hop("from", fromkey, &d->from) != 0) 457 continue; 458 459 /* Match 'to' key */ 460 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 461 continue; 462 463 /* Match user if specified */ 464 if (d->to.user != NULL && user != NULL && 465 !match_pattern(user, d->to.user)) 466 continue; 467 468 /* successfully matched this constraint */ 469 if (hostnamep != NULL) 470 *hostnamep = d->to.hostname; 471 debug2_f("allowed for hostname %s", 472 d->to.hostname == NULL ? "*" : d->to.hostname); 473 return 0; 474 } 475 /* no match */ 476 debug2_f("%s identity \"%s\" not permitted for this destination", 477 sshkey_type(id->key), id->comment); 478 return -1; 479 } 480 481 /* 482 * Check whether hostkeys on a SocketEntry and the optionally specified user 483 * are permitted by the destination constraints on the Identity. 484 * Returns 0 on success or -1 otherwise. 485 */ 486 static int 487 identity_permitted(Identity *id, SocketEntry *e, char *user, 488 const char **forward_hostnamep, const char **last_hostnamep) 489 { 490 size_t i; 491 const char **hp; 492 struct hostkey_sid *hks; 493 const struct sshkey *fromkey = NULL; 494 const char *test_user; 495 char *fp1, *fp2; 496 497 /* XXX remove logspam */ 498 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 499 "%zu constraints", sshkey_type(id->key), id->comment, 500 e->nsession_ids, id->ndest_constraints); 501 if (id->ndest_constraints == 0) 502 return 0; /* unconstrained */ 503 if (e->session_bind_attempted && e->nsession_ids == 0) { 504 error_f("previous session bind failed on socket"); 505 return -1; 506 } 507 if (e->nsession_ids == 0) 508 return 0; /* local use */ 509 /* 510 * Walk through the hops recorded by session_id and try to find a 511 * constraint that satisfies each. 512 */ 513 for (i = 0; i < e->nsession_ids; i++) { 514 hks = e->session_ids + i; 515 if (hks->key == NULL) 516 fatal_f("internal error: no bound key"); 517 /* XXX remove logspam */ 518 fp1 = fp2 = NULL; 519 if (fromkey != NULL && 520 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 521 SSH_FP_DEFAULT)) == NULL) 522 fatal_f("fingerprint failed"); 523 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 524 SSH_FP_DEFAULT)) == NULL) 525 fatal_f("fingerprint failed"); 526 debug3_f("socketentry fd=%d, entry %zu %s, " 527 "from hostkey %s %s to user %s hostkey %s %s", 528 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 529 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 530 fromkey ? fp1 : "", user ? user : "(ANY)", 531 sshkey_type(hks->key), fp2); 532 free(fp1); 533 free(fp2); 534 /* 535 * Record the hostnames for the initial forwarding and 536 * the final destination. 537 */ 538 hp = NULL; 539 if (i == e->nsession_ids - 1) 540 hp = last_hostnamep; 541 else if (i == 0) 542 hp = forward_hostnamep; 543 /* Special handling for final recorded binding */ 544 test_user = NULL; 545 if (i == e->nsession_ids - 1) { 546 /* Can only check user at final hop */ 547 test_user = user; 548 /* 549 * user is only presented for signature requests. 550 * If this is the case, make sure last binding is not 551 * for a forwarding. 552 */ 553 if (hks->forwarded && user != NULL) { 554 error_f("tried to sign on forwarding hop"); 555 return -1; 556 } 557 } else if (!hks->forwarded) { 558 error_f("tried to forward though signing bind"); 559 return -1; 560 } 561 if (permitted_by_dest_constraints(fromkey, hks->key, id, 562 test_user, hp) != 0) 563 return -1; 564 fromkey = hks->key; 565 } 566 /* 567 * Another special case: if the last bound session ID was for a 568 * forwarding, and this function is not being called to check a sign 569 * request (i.e. no 'user' supplied), then only permit the key if 570 * there is a permission that would allow it to be used at another 571 * destination. This hides keys that are allowed to be used to 572 * authenticate *to* a host but not permitted for *use* beyond it. 573 */ 574 hks = &e->session_ids[e->nsession_ids - 1]; 575 if (hks->forwarded && user == NULL && 576 permitted_by_dest_constraints(hks->key, NULL, id, 577 NULL, NULL) != 0) { 578 debug3_f("key permitted at host but not after"); 579 return -1; 580 } 581 582 /* success */ 583 return 0; 584 } 585 586 static int 587 socket_is_remote(SocketEntry *e) 588 { 589 return e->session_bind_attempted || (e->nsession_ids != 0); 590 } 591 592 /* return matching private key for given public key */ 593 static Identity * 594 lookup_identity(struct sshkey *key) 595 { 596 Identity *id; 597 598 TAILQ_FOREACH(id, &idtab->idlist, next) { 599 if (sshkey_equal(key, id->key)) 600 return (id); 601 } 602 return (NULL); 603 } 604 605 /* Check confirmation of keysign request */ 606 static int 607 confirm_key(Identity *id, const char *extra) 608 { 609 char *p; 610 int ret = -1; 611 612 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 613 if (p != NULL && 614 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 615 id->comment, p, 616 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 617 ret = 0; 618 free(p); 619 620 return (ret); 621 } 622 623 static void 624 send_status(SocketEntry *e, int success) 625 { 626 int r; 627 628 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 629 (r = sshbuf_put_u8(e->output, success ? 630 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 631 fatal_fr(r, "compose"); 632 } 633 634 /* send list of supported public keys to 'client' */ 635 static void 636 process_request_identities(SocketEntry *e) 637 { 638 Identity *id; 639 struct sshbuf *msg, *keys; 640 int r; 641 u_int i = 0, nentries = 0; 642 char *fp; 643 644 debug2_f("entering"); 645 646 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 647 fatal_f("sshbuf_new failed"); 648 TAILQ_FOREACH(id, &idtab->idlist, next) { 649 if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT, 650 SSH_FP_DEFAULT)) == NULL) 651 fatal_f("fingerprint failed"); 652 debug_f("key %u / %u: %s %s", i++, idtab->nentries, 653 sshkey_ssh_name(id->key), fp); 654 dump_dest_constraints(__func__, 655 id->dest_constraints, id->ndest_constraints); 656 free(fp); 657 /* identity not visible, don't include in response */ 658 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 659 continue; 660 if ((r = sshkey_puts_opts(id->key, keys, 661 SSHKEY_SERIALIZE_INFO)) != 0 || 662 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 663 error_fr(r, "compose key/comment"); 664 continue; 665 } 666 nentries++; 667 } 668 debug2_f("replying with %u allowed of %u available keys", 669 nentries, idtab->nentries); 670 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 671 (r = sshbuf_put_u32(msg, nentries)) != 0 || 672 (r = sshbuf_putb(msg, keys)) != 0) 673 fatal_fr(r, "compose"); 674 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 675 fatal_fr(r, "enqueue"); 676 sshbuf_free(msg); 677 sshbuf_free(keys); 678 } 679 680 681 static char * 682 agent_decode_alg(struct sshkey *key, u_int flags) 683 { 684 if (key->type == KEY_RSA) { 685 if (flags & SSH_AGENT_RSA_SHA2_256) 686 return "rsa-sha2-256"; 687 else if (flags & SSH_AGENT_RSA_SHA2_512) 688 return "rsa-sha2-512"; 689 } else if (key->type == KEY_RSA_CERT) { 690 if (flags & SSH_AGENT_RSA_SHA2_256) 691 return "rsa-sha2-256-cert-v01@openssh.com"; 692 else if (flags & SSH_AGENT_RSA_SHA2_512) 693 return "rsa-sha2-512-cert-v01@openssh.com"; 694 } 695 return NULL; 696 } 697 698 /* 699 * Attempt to parse the contents of a buffer as a SSH publickey userauth 700 * request, checking its contents for consistency and matching the embedded 701 * key against the one that is being used for signing. 702 * Note: does not modify msg buffer. 703 * Optionally extract the username, session ID and/or hostkey from the request. 704 */ 705 static int 706 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 707 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 708 { 709 struct sshbuf *b = NULL, *sess_id = NULL; 710 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 711 int r; 712 u_char t, sig_follows; 713 struct sshkey *mkey = NULL, *hostkey = NULL; 714 715 if (userp != NULL) 716 *userp = NULL; 717 if (sess_idp != NULL) 718 *sess_idp = NULL; 719 if (hostkeyp != NULL) 720 *hostkeyp = NULL; 721 if ((b = sshbuf_fromb(msg)) == NULL) 722 fatal_f("sshbuf_fromb"); 723 724 /* SSH userauth request */ 725 if ((r = sshbuf_froms(b, &sess_id)) != 0) 726 goto out; 727 if (sshbuf_len(sess_id) == 0) { 728 r = SSH_ERR_INVALID_FORMAT; 729 goto out; 730 } 731 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 732 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 733 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 734 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 735 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 736 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 737 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 738 goto out; 739 if (t != SSH2_MSG_USERAUTH_REQUEST || 740 sig_follows != 1 || 741 strcmp(service, "ssh-connection") != 0 || 742 !sshkey_equal(expected_key, mkey) || 743 sshkey_type_from_name(pkalg) != expected_key->type) { 744 r = SSH_ERR_INVALID_FORMAT; 745 goto out; 746 } 747 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 748 if ((r = sshkey_froms(b, &hostkey)) != 0) 749 goto out; 750 } else if (strcmp(method, "publickey") != 0) { 751 r = SSH_ERR_INVALID_FORMAT; 752 goto out; 753 } 754 if (sshbuf_len(b) != 0) { 755 r = SSH_ERR_INVALID_FORMAT; 756 goto out; 757 } 758 /* success */ 759 r = 0; 760 debug3_f("well formed userauth"); 761 if (userp != NULL) { 762 *userp = user; 763 user = NULL; 764 } 765 if (sess_idp != NULL) { 766 *sess_idp = sess_id; 767 sess_id = NULL; 768 } 769 if (hostkeyp != NULL) { 770 *hostkeyp = hostkey; 771 hostkey = NULL; 772 } 773 out: 774 sshbuf_free(b); 775 sshbuf_free(sess_id); 776 free(user); 777 free(service); 778 free(method); 779 free(pkalg); 780 sshkey_free(mkey); 781 sshkey_free(hostkey); 782 return r; 783 } 784 785 /* 786 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 787 * Note: does not modify buffer. 788 */ 789 static int 790 parse_sshsig_request(struct sshbuf *msg) 791 { 792 int r; 793 struct sshbuf *b; 794 795 if ((b = sshbuf_fromb(msg)) == NULL) 796 fatal_f("sshbuf_fromb"); 797 798 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 799 (r = sshbuf_consume(b, 6)) != 0 || 800 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 801 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 802 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 803 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 804 goto out; 805 if (sshbuf_len(b) != 0) { 806 r = SSH_ERR_INVALID_FORMAT; 807 goto out; 808 } 809 /* success */ 810 r = 0; 811 out: 812 sshbuf_free(b); 813 return r; 814 } 815 816 /* 817 * This function inspects a message to be signed by a FIDO key that has a 818 * web-like application string (i.e. one that does not begin with "ssh:". 819 * It checks that the message is one of those expected for SSH operations 820 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 821 * for the web. 822 */ 823 static int 824 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 825 { 826 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 827 debug_f("signed data matches public key userauth request"); 828 return 1; 829 } 830 if (parse_sshsig_request(data) == 0) { 831 debug_f("signed data matches SSHSIG signature request"); 832 return 1; 833 } 834 835 /* XXX check CA signature operation */ 836 837 error("web-origin key attempting to sign non-SSH message"); 838 return 0; 839 } 840 841 static int 842 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 843 { 844 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 845 return SSH_ERR_INVALID_ARGUMENT; 846 if (sshbuf_len(a) != sshbuf_len(b)) 847 return SSH_ERR_INVALID_FORMAT; 848 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 849 return SSH_ERR_INVALID_FORMAT; 850 return 0; 851 } 852 853 /* ssh2 only */ 854 static void 855 process_sign_request2(SocketEntry *e) 856 { 857 u_char *signature = NULL; 858 size_t slen = 0; 859 u_int compat = 0, flags; 860 int r, ok = -1, retried = 0; 861 char *fp = NULL, *pin = NULL, *prompt = NULL; 862 char *user = NULL, *sig_dest = NULL; 863 const char *fwd_host = NULL, *dest_host = NULL; 864 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 865 struct sshkey *key = NULL, *hostkey = NULL; 866 struct identity *id; 867 struct notifier_ctx *notifier = NULL; 868 869 debug_f("entering"); 870 871 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 872 fatal_f("sshbuf_new failed"); 873 if ((r = sshkey_froms(e->request, &key)) != 0 || 874 (r = sshbuf_get_stringb(e->request, data)) != 0 || 875 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 876 error_fr(r, "parse"); 877 goto send; 878 } 879 880 if ((id = lookup_identity(key)) == NULL) { 881 verbose_f("%s key not found", sshkey_type(key)); 882 goto send; 883 } 884 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 885 SSH_FP_DEFAULT)) == NULL) 886 fatal_f("fingerprint failed"); 887 888 if (id->ndest_constraints != 0) { 889 if (e->nsession_ids == 0) { 890 logit_f("refusing use of destination-constrained key " 891 "to sign on unbound connection"); 892 goto send; 893 } 894 if (parse_userauth_request(data, key, &user, &sid, 895 &hostkey) != 0) { 896 logit_f("refusing use of destination-constrained key " 897 "to sign an unidentified signature"); 898 goto send; 899 } 900 /* XXX logspam */ 901 debug_f("user=%s", user); 902 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 903 goto send; 904 /* XXX display fwd_host/dest_host in askpass UI */ 905 /* 906 * Ensure that the session ID is the most recent one 907 * registered on the socket - it should have been bound by 908 * ssh immediately before userauth. 909 */ 910 if (buf_equal(sid, 911 e->session_ids[e->nsession_ids - 1].sid) != 0) { 912 error_f("unexpected session ID (%zu listed) on " 913 "signature request for target user %s with " 914 "key %s %s", e->nsession_ids, user, 915 sshkey_type(id->key), fp); 916 goto send; 917 } 918 /* 919 * Ensure that the hostkey embedded in the signature matches 920 * the one most recently bound to the socket. An exception is 921 * made for the initial forwarding hop. 922 */ 923 if (e->nsession_ids > 1 && hostkey == NULL) { 924 error_f("refusing use of destination-constrained key: " 925 "no hostkey recorded in signature for forwarded " 926 "connection"); 927 goto send; 928 } 929 if (hostkey != NULL && !sshkey_equal(hostkey, 930 e->session_ids[e->nsession_ids - 1].key)) { 931 error_f("refusing use of destination-constrained key: " 932 "mismatch between hostkey in request and most " 933 "recently bound session"); 934 goto send; 935 } 936 xasprintf(&sig_dest, "public key authentication request for " 937 "user \"%s\" to listed host", user); 938 } 939 if (id->confirm && confirm_key(id, sig_dest) != 0) { 940 verbose_f("user refused key"); 941 goto send; 942 } 943 if (sshkey_is_sk(id->key)) { 944 if (restrict_websafe && 945 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 946 !check_websafe_message_contents(key, data)) { 947 /* error already logged */ 948 goto send; 949 } 950 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 951 notifier = notify_start(0, 952 "Confirm user presence for key %s %s%s%s", 953 sshkey_type(id->key), fp, 954 sig_dest == NULL ? "" : "\n", 955 sig_dest == NULL ? "" : sig_dest); 956 } 957 } 958 retry_pin: 959 if ((r = sshkey_sign(id->key, &signature, &slen, 960 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 961 id->sk_provider, pin, compat)) != 0) { 962 debug_fr(r, "sshkey_sign"); 963 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 964 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 965 notify_complete(notifier, NULL); 966 notifier = NULL; 967 /* XXX include sig_dest */ 968 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 969 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 970 " and confirm user presence " : " ", 971 sshkey_type(id->key), fp); 972 pin = read_passphrase(prompt, RP_USE_ASKPASS); 973 retried = 1; 974 goto retry_pin; 975 } 976 error_fr(r, "sshkey_sign"); 977 goto send; 978 } 979 /* Success */ 980 ok = 0; 981 debug_f("good signature"); 982 send: 983 notify_complete(notifier, "User presence confirmed"); 984 985 if (ok == 0) { 986 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 987 (r = sshbuf_put_string(msg, signature, slen)) != 0) 988 fatal_fr(r, "compose"); 989 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 990 fatal_fr(r, "compose failure"); 991 992 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 993 fatal_fr(r, "enqueue"); 994 995 sshbuf_free(sid); 996 sshbuf_free(data); 997 sshbuf_free(msg); 998 sshkey_free(key); 999 sshkey_free(hostkey); 1000 free(fp); 1001 free(signature); 1002 free(sig_dest); 1003 free(user); 1004 free(prompt); 1005 if (pin != NULL) 1006 freezero(pin, strlen(pin)); 1007 } 1008 1009 /* shared */ 1010 static void 1011 process_remove_identity(SocketEntry *e) 1012 { 1013 int r, success = 0; 1014 struct sshkey *key = NULL; 1015 Identity *id; 1016 1017 debug2_f("entering"); 1018 if ((r = sshkey_froms(e->request, &key)) != 0) { 1019 error_fr(r, "parse key"); 1020 goto done; 1021 } 1022 if ((id = lookup_identity(key)) == NULL) { 1023 debug_f("key not found"); 1024 goto done; 1025 } 1026 /* identity not visible, cannot be removed */ 1027 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1028 goto done; /* error already logged */ 1029 /* We have this key, free it. */ 1030 if (idtab->nentries < 1) 1031 fatal_f("internal error: nentries %d", idtab->nentries); 1032 TAILQ_REMOVE(&idtab->idlist, id, next); 1033 free_identity(id); 1034 idtab->nentries--; 1035 success = 1; 1036 done: 1037 sshkey_free(key); 1038 send_status(e, success); 1039 } 1040 1041 static void 1042 process_remove_all_identities(SocketEntry *e) 1043 { 1044 Identity *id; 1045 1046 debug2_f("entering"); 1047 /* Loop over all identities and clear the keys. */ 1048 for (id = TAILQ_FIRST(&idtab->idlist); id; 1049 id = TAILQ_FIRST(&idtab->idlist)) { 1050 TAILQ_REMOVE(&idtab->idlist, id, next); 1051 free_identity(id); 1052 } 1053 1054 /* Mark that there are no identities. */ 1055 idtab->nentries = 0; 1056 1057 /* Send success. */ 1058 send_status(e, 1); 1059 } 1060 1061 /* removes expired keys and returns number of seconds until the next expiry */ 1062 static time_t 1063 reaper(void) 1064 { 1065 time_t deadline = 0, now = monotime(); 1066 Identity *id, *nxt; 1067 1068 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1069 nxt = TAILQ_NEXT(id, next); 1070 if (id->death == 0) 1071 continue; 1072 if (now >= id->death) { 1073 debug("expiring key '%s'", id->comment); 1074 TAILQ_REMOVE(&idtab->idlist, id, next); 1075 free_identity(id); 1076 idtab->nentries--; 1077 } else 1078 deadline = (deadline == 0) ? id->death : 1079 MINIMUM(deadline, id->death); 1080 } 1081 if (deadline == 0 || deadline <= now) 1082 return 0; 1083 else 1084 return (deadline - now); 1085 } 1086 1087 static int 1088 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 1089 { 1090 u_char key_is_ca; 1091 size_t elen = 0; 1092 int r; 1093 struct sshkey *k = NULL; 1094 char *fp; 1095 1096 memset(dch, '\0', sizeof(*dch)); 1097 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 1098 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 1099 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1100 error_fr(r, "parse"); 1101 goto out; 1102 } 1103 if (elen != 0) { 1104 error_f("unsupported extensions (len %zu)", elen); 1105 r = SSH_ERR_FEATURE_UNSUPPORTED; 1106 goto out; 1107 } 1108 if (*dch->hostname == '\0') { 1109 free(dch->hostname); 1110 dch->hostname = NULL; 1111 } 1112 if (*dch->user == '\0') { 1113 free(dch->user); 1114 dch->user = NULL; 1115 } 1116 while (sshbuf_len(b) != 0) { 1117 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1118 dch->nkeys + 1, sizeof(*dch->keys)); 1119 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1120 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1121 if ((r = sshkey_froms(b, &k)) != 0 || 1122 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1123 goto out; 1124 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1125 SSH_FP_DEFAULT)) == NULL) 1126 fatal_f("fingerprint failed"); 1127 debug3_f("%s%s%s: adding %skey %s %s", 1128 dch->user == NULL ? "" : dch->user, 1129 dch->user == NULL ? "" : "@", 1130 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1131 free(fp); 1132 dch->keys[dch->nkeys] = k; 1133 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1134 dch->nkeys++; 1135 k = NULL; /* transferred */ 1136 } 1137 /* success */ 1138 r = 0; 1139 out: 1140 sshkey_free(k); 1141 return r; 1142 } 1143 1144 static int 1145 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1146 { 1147 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1148 int r; 1149 size_t elen = 0; 1150 1151 debug3_f("entering"); 1152 1153 memset(dc, '\0', sizeof(*dc)); 1154 if ((r = sshbuf_froms(m, &b)) != 0 || 1155 (r = sshbuf_froms(b, &frombuf)) != 0 || 1156 (r = sshbuf_froms(b, &tobuf)) != 0 || 1157 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1158 error_fr(r, "parse"); 1159 goto out; 1160 } 1161 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1162 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1163 goto out; /* already logged */ 1164 if (elen != 0) { 1165 error_f("unsupported extensions (len %zu)", elen); 1166 r = SSH_ERR_FEATURE_UNSUPPORTED; 1167 goto out; 1168 } 1169 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1170 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1171 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1172 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1173 /* check consistency */ 1174 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1175 dc->from.user != NULL) { 1176 error_f("inconsistent \"from\" specification"); 1177 r = SSH_ERR_INVALID_FORMAT; 1178 goto out; 1179 } 1180 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1181 error_f("incomplete \"to\" specification"); 1182 r = SSH_ERR_INVALID_FORMAT; 1183 goto out; 1184 } 1185 /* success */ 1186 r = 0; 1187 out: 1188 sshbuf_free(b); 1189 sshbuf_free(frombuf); 1190 sshbuf_free(tobuf); 1191 return r; 1192 } 1193 1194 static int 1195 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1196 struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp, 1197 struct sshkey ***certs, size_t *ncerts) 1198 { 1199 char *ext_name = NULL; 1200 int r; 1201 struct sshbuf *b = NULL; 1202 u_char v; 1203 struct sshkey *k; 1204 1205 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1206 error_fr(r, "parse constraint extension"); 1207 goto out; 1208 } 1209 debug_f("constraint ext %s", ext_name); 1210 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1211 if (sk_providerp == NULL) { 1212 error_f("%s not valid here", ext_name); 1213 r = SSH_ERR_INVALID_FORMAT; 1214 goto out; 1215 } 1216 if (*sk_providerp != NULL) { 1217 error_f("%s already set", ext_name); 1218 r = SSH_ERR_INVALID_FORMAT; 1219 goto out; 1220 } 1221 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1222 error_fr(r, "parse %s", ext_name); 1223 goto out; 1224 } 1225 } else if (strcmp(ext_name, 1226 "restrict-destination-v00@openssh.com") == 0) { 1227 if (*dcsp != NULL) { 1228 error_f("%s already set", ext_name); 1229 goto out; 1230 } 1231 if ((r = sshbuf_froms(m, &b)) != 0) { 1232 error_fr(r, "parse %s outer", ext_name); 1233 goto out; 1234 } 1235 while (sshbuf_len(b) != 0) { 1236 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1237 error_f("too many %s constraints", ext_name); 1238 goto out; 1239 } 1240 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1241 sizeof(**dcsp)); 1242 if ((r = parse_dest_constraint(b, 1243 *dcsp + (*ndcsp)++)) != 0) 1244 goto out; /* error already logged */ 1245 } 1246 } else if (strcmp(ext_name, 1247 "associated-certs-v00@openssh.com") == 0) { 1248 if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) { 1249 error_f("%s not valid here", ext_name); 1250 r = SSH_ERR_INVALID_FORMAT; 1251 goto out; 1252 } 1253 if (*certs != NULL) { 1254 error_f("%s already set", ext_name); 1255 goto out; 1256 } 1257 if ((r = sshbuf_get_u8(m, &v)) != 0 || 1258 (r = sshbuf_froms(m, &b)) != 0) { 1259 error_fr(r, "parse %s", ext_name); 1260 goto out; 1261 } 1262 *cert_onlyp = v != 0; 1263 while (sshbuf_len(b) != 0) { 1264 if (*ncerts >= AGENT_MAX_EXT_CERTS) { 1265 error_f("too many %s constraints", ext_name); 1266 goto out; 1267 } 1268 *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1, 1269 sizeof(**certs)); 1270 if ((r = sshkey_froms(b, &k)) != 0) { 1271 error_fr(r, "parse key"); 1272 goto out; 1273 } 1274 (*certs)[(*ncerts)++] = k; 1275 } 1276 } else { 1277 error_f("unsupported constraint \"%s\"", ext_name); 1278 r = SSH_ERR_FEATURE_UNSUPPORTED; 1279 goto out; 1280 } 1281 /* success */ 1282 r = 0; 1283 out: 1284 free(ext_name); 1285 sshbuf_free(b); 1286 return r; 1287 } 1288 1289 static int 1290 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1291 u_int *secondsp, int *confirmp, char **sk_providerp, 1292 struct dest_constraint **dcsp, size_t *ndcsp, 1293 int *cert_onlyp, size_t *ncerts, struct sshkey ***certs) 1294 { 1295 u_char ctype; 1296 int r; 1297 u_int seconds, maxsign = 0; 1298 1299 while (sshbuf_len(m)) { 1300 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1301 error_fr(r, "parse constraint type"); 1302 goto out; 1303 } 1304 switch (ctype) { 1305 case SSH_AGENT_CONSTRAIN_LIFETIME: 1306 if (*deathp != 0) { 1307 error_f("lifetime already set"); 1308 r = SSH_ERR_INVALID_FORMAT; 1309 goto out; 1310 } 1311 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1312 error_fr(r, "parse lifetime constraint"); 1313 goto out; 1314 } 1315 *deathp = monotime() + seconds; 1316 *secondsp = seconds; 1317 break; 1318 case SSH_AGENT_CONSTRAIN_CONFIRM: 1319 if (*confirmp != 0) { 1320 error_f("confirm already set"); 1321 r = SSH_ERR_INVALID_FORMAT; 1322 goto out; 1323 } 1324 *confirmp = 1; 1325 break; 1326 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1327 if (k == NULL) { 1328 error_f("maxsign not valid here"); 1329 r = SSH_ERR_INVALID_FORMAT; 1330 goto out; 1331 } 1332 if (maxsign != 0) { 1333 error_f("maxsign already set"); 1334 r = SSH_ERR_INVALID_FORMAT; 1335 goto out; 1336 } 1337 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1338 error_fr(r, "parse maxsign constraint"); 1339 goto out; 1340 } 1341 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1342 error_fr(r, "enable maxsign"); 1343 goto out; 1344 } 1345 break; 1346 case SSH_AGENT_CONSTRAIN_EXTENSION: 1347 if ((r = parse_key_constraint_extension(m, 1348 sk_providerp, dcsp, ndcsp, 1349 cert_onlyp, certs, ncerts)) != 0) 1350 goto out; /* error already logged */ 1351 break; 1352 default: 1353 error_f("Unknown constraint %d", ctype); 1354 r = SSH_ERR_FEATURE_UNSUPPORTED; 1355 goto out; 1356 } 1357 } 1358 /* success */ 1359 r = 0; 1360 out: 1361 return r; 1362 } 1363 1364 static void 1365 process_add_identity(SocketEntry *e) 1366 { 1367 Identity *id; 1368 int success = 0, confirm = 0; 1369 char *fp, *comment = NULL, *sk_provider = NULL; 1370 char canonical_provider[PATH_MAX]; 1371 time_t death = 0; 1372 u_int seconds = 0; 1373 struct dest_constraint *dest_constraints = NULL; 1374 size_t ndest_constraints = 0; 1375 struct sshkey *k = NULL; 1376 int r = SSH_ERR_INTERNAL_ERROR; 1377 1378 debug2_f("entering"); 1379 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1380 k == NULL || 1381 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1382 error_fr(r, "parse"); 1383 goto out; 1384 } 1385 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1386 &sk_provider, &dest_constraints, &ndest_constraints, 1387 NULL, NULL, NULL) != 0) { 1388 error_f("failed to parse constraints"); 1389 sshbuf_reset(e->request); 1390 goto out; 1391 } 1392 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1393 1394 if (sk_provider != NULL) { 1395 if (!sshkey_is_sk(k)) { 1396 error("Cannot add provider: %s is not an " 1397 "authenticator-hosted key", sshkey_type(k)); 1398 goto out; 1399 } 1400 if (strcasecmp(sk_provider, "internal") == 0) { 1401 debug_f("internal provider"); 1402 } else { 1403 if (socket_is_remote(e) && !remote_add_provider) { 1404 verbose("failed add of SK provider \"%.100s\": " 1405 "remote addition of providers is disabled", 1406 sk_provider); 1407 goto out; 1408 } 1409 if (realpath(sk_provider, canonical_provider) == NULL) { 1410 verbose("failed provider \"%.100s\": " 1411 "realpath: %s", sk_provider, 1412 strerror(errno)); 1413 goto out; 1414 } 1415 free(sk_provider); 1416 sk_provider = xstrdup(canonical_provider); 1417 if (match_pattern_list(sk_provider, 1418 allowed_providers, 0) != 1) { 1419 error("Refusing add key: " 1420 "provider %s not allowed", sk_provider); 1421 goto out; 1422 } 1423 } 1424 } 1425 if ((r = sshkey_shield_private(k)) != 0) { 1426 error_fr(r, "shield private"); 1427 goto out; 1428 } 1429 if (lifetime && !death) 1430 death = monotime() + lifetime; 1431 if ((id = lookup_identity(k)) == NULL) { 1432 id = xcalloc(1, sizeof(Identity)); 1433 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1434 /* Increment the number of identities. */ 1435 idtab->nentries++; 1436 } else { 1437 /* identity not visible, do not update */ 1438 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1439 goto out; /* error already logged */ 1440 /* key state might have been updated */ 1441 sshkey_free(id->key); 1442 free(id->comment); 1443 free(id->sk_provider); 1444 free_dest_constraints(id->dest_constraints, 1445 id->ndest_constraints); 1446 } 1447 /* success */ 1448 id->key = k; 1449 id->comment = comment; 1450 id->death = death; 1451 id->confirm = confirm; 1452 id->sk_provider = sk_provider; 1453 id->dest_constraints = dest_constraints; 1454 id->ndest_constraints = ndest_constraints; 1455 1456 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1457 SSH_FP_DEFAULT)) == NULL) 1458 fatal_f("sshkey_fingerprint failed"); 1459 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1460 "(provider: %s) (destination constraints: %zu)", 1461 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1462 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1463 free(fp); 1464 /* transferred */ 1465 k = NULL; 1466 comment = NULL; 1467 sk_provider = NULL; 1468 dest_constraints = NULL; 1469 ndest_constraints = 0; 1470 success = 1; 1471 out: 1472 free(sk_provider); 1473 free(comment); 1474 sshkey_free(k); 1475 free_dest_constraints(dest_constraints, ndest_constraints); 1476 send_status(e, success); 1477 } 1478 1479 /* XXX todo: encrypt sensitive data with passphrase */ 1480 static void 1481 process_lock_agent(SocketEntry *e, int lock) 1482 { 1483 int r, success = 0, delay; 1484 char *passwd; 1485 u_char passwdhash[LOCK_SIZE]; 1486 static u_int fail_count = 0; 1487 size_t pwlen; 1488 1489 debug2_f("entering"); 1490 /* 1491 * This is deliberately fatal: the user has requested that we lock, 1492 * but we can't parse their request properly. The only safe thing to 1493 * do is abort. 1494 */ 1495 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1496 fatal_fr(r, "parse"); 1497 if (pwlen == 0) { 1498 debug("empty password not supported"); 1499 } else if (locked && !lock) { 1500 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1501 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1502 fatal("bcrypt_pbkdf"); 1503 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1504 debug("agent unlocked"); 1505 locked = 0; 1506 fail_count = 0; 1507 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1508 success = 1; 1509 } else { 1510 /* delay in 0.1s increments up to 10s */ 1511 if (fail_count < 100) 1512 fail_count++; 1513 delay = 100000 * fail_count; 1514 debug("unlock failed, delaying %0.1lf seconds", 1515 (double)delay/1000000); 1516 usleep(delay); 1517 } 1518 explicit_bzero(passwdhash, sizeof(passwdhash)); 1519 } else if (!locked && lock) { 1520 debug("agent locked"); 1521 locked = 1; 1522 arc4random_buf(lock_salt, sizeof(lock_salt)); 1523 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1524 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1525 fatal("bcrypt_pbkdf"); 1526 success = 1; 1527 } 1528 freezero(passwd, pwlen); 1529 send_status(e, success); 1530 } 1531 1532 static void 1533 no_identities(SocketEntry *e) 1534 { 1535 struct sshbuf *msg; 1536 int r; 1537 1538 if ((msg = sshbuf_new()) == NULL) 1539 fatal_f("sshbuf_new failed"); 1540 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1541 (r = sshbuf_put_u32(msg, 0)) != 0 || 1542 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1543 fatal_fr(r, "compose"); 1544 sshbuf_free(msg); 1545 } 1546 1547 #ifdef ENABLE_PKCS11 1548 /* Add an identity to idlist; takes ownership of 'key' and 'comment' */ 1549 static void 1550 add_p11_identity(struct sshkey *key, char *comment, const char *provider, 1551 time_t death, u_int confirm, struct dest_constraint *dest_constraints, 1552 size_t ndest_constraints) 1553 { 1554 Identity *id; 1555 1556 if (lookup_identity(key) != NULL) { 1557 sshkey_free(key); 1558 free(comment); 1559 return; 1560 } 1561 id = xcalloc(1, sizeof(Identity)); 1562 id->key = key; 1563 id->comment = comment; 1564 id->provider = xstrdup(provider); 1565 id->death = death; 1566 id->confirm = confirm; 1567 id->dest_constraints = dup_dest_constraints(dest_constraints, 1568 ndest_constraints); 1569 id->ndest_constraints = ndest_constraints; 1570 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1571 idtab->nentries++; 1572 } 1573 1574 static void 1575 process_add_smartcard_key(SocketEntry *e) 1576 { 1577 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1578 char **comments = NULL; 1579 int r, i, count = 0, success = 0, confirm = 0; 1580 u_int seconds = 0; 1581 time_t death = 0; 1582 struct sshkey **keys = NULL, *k; 1583 struct dest_constraint *dest_constraints = NULL; 1584 size_t j, ndest_constraints = 0, ncerts = 0; 1585 struct sshkey **certs = NULL; 1586 int cert_only = 0; 1587 1588 debug2_f("entering"); 1589 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1590 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1591 error_fr(r, "parse"); 1592 goto send; 1593 } 1594 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1595 NULL, &dest_constraints, &ndest_constraints, &cert_only, 1596 &ncerts, &certs) != 0) { 1597 error_f("failed to parse constraints"); 1598 goto send; 1599 } 1600 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1601 if (socket_is_remote(e) && !remote_add_provider) { 1602 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1603 "providers is disabled", provider); 1604 goto send; 1605 } 1606 if (realpath(provider, canonical_provider) == NULL) { 1607 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1608 provider, strerror(errno)); 1609 goto send; 1610 } 1611 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1612 verbose("refusing PKCS#11 add of \"%.100s\": " 1613 "provider not allowed", canonical_provider); 1614 goto send; 1615 } 1616 debug_f("add %.100s", canonical_provider); 1617 if (lifetime && !death) 1618 death = monotime() + lifetime; 1619 1620 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1621 for (i = 0; i < count; i++) { 1622 if (comments[i] == NULL || comments[i][0] == '\0') { 1623 free(comments[i]); 1624 comments[i] = xstrdup(canonical_provider); 1625 } 1626 for (j = 0; j < ncerts; j++) { 1627 if (!sshkey_is_cert(certs[j])) 1628 continue; 1629 if (!sshkey_equal_public(keys[i], certs[j])) 1630 continue; 1631 if (pkcs11_make_cert(keys[i], certs[j], &k) != 0) 1632 continue; 1633 add_p11_identity(k, xstrdup(comments[i]), 1634 canonical_provider, death, confirm, 1635 dest_constraints, ndest_constraints); 1636 success = 1; 1637 } 1638 if (!cert_only && lookup_identity(keys[i]) == NULL) { 1639 add_p11_identity(keys[i], comments[i], 1640 canonical_provider, death, confirm, 1641 dest_constraints, ndest_constraints); 1642 keys[i] = NULL; /* transferred */ 1643 comments[i] = NULL; /* transferred */ 1644 success = 1; 1645 } 1646 /* XXX update constraints for existing keys */ 1647 sshkey_free(keys[i]); 1648 free(comments[i]); 1649 } 1650 send: 1651 free(pin); 1652 free(provider); 1653 free(keys); 1654 free(comments); 1655 free_dest_constraints(dest_constraints, ndest_constraints); 1656 for (j = 0; j < ncerts; j++) 1657 sshkey_free(certs[j]); 1658 free(certs); 1659 send_status(e, success); 1660 } 1661 1662 static void 1663 process_remove_smartcard_key(SocketEntry *e) 1664 { 1665 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1666 int r, success = 0; 1667 Identity *id, *nxt; 1668 1669 debug2_f("entering"); 1670 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1671 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1672 error_fr(r, "parse"); 1673 goto send; 1674 } 1675 free(pin); 1676 1677 if (realpath(provider, canonical_provider) == NULL) { 1678 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1679 provider, strerror(errno)); 1680 goto send; 1681 } 1682 1683 debug_f("remove %.100s", canonical_provider); 1684 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1685 nxt = TAILQ_NEXT(id, next); 1686 /* Skip file--based keys */ 1687 if (id->provider == NULL) 1688 continue; 1689 if (!strcmp(canonical_provider, id->provider)) { 1690 TAILQ_REMOVE(&idtab->idlist, id, next); 1691 free_identity(id); 1692 idtab->nentries--; 1693 } 1694 } 1695 if (pkcs11_del_provider(canonical_provider) == 0) 1696 success = 1; 1697 else 1698 error_f("pkcs11_del_provider failed"); 1699 send: 1700 free(provider); 1701 send_status(e, success); 1702 } 1703 #endif /* ENABLE_PKCS11 */ 1704 1705 static int 1706 process_ext_session_bind(SocketEntry *e) 1707 { 1708 int r, sid_match, key_match; 1709 struct sshkey *key = NULL; 1710 struct sshbuf *sid = NULL, *sig = NULL; 1711 char *fp = NULL; 1712 size_t i; 1713 u_char fwd = 0; 1714 1715 debug2_f("entering"); 1716 e->session_bind_attempted = 1; 1717 if ((r = sshkey_froms(e->request, &key)) != 0 || 1718 (r = sshbuf_froms(e->request, &sid)) != 0 || 1719 (r = sshbuf_froms(e->request, &sig)) != 0 || 1720 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1721 error_fr(r, "parse"); 1722 goto out; 1723 } 1724 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1725 SSH_FP_DEFAULT)) == NULL) 1726 fatal_f("fingerprint failed"); 1727 /* check signature with hostkey on session ID */ 1728 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1729 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1730 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1731 goto out; 1732 } 1733 /* check whether sid/key already recorded */ 1734 for (i = 0; i < e->nsession_ids; i++) { 1735 if (!e->session_ids[i].forwarded) { 1736 error_f("attempt to bind session ID to socket " 1737 "previously bound for authentication attempt"); 1738 r = -1; 1739 goto out; 1740 } 1741 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1742 key_match = sshkey_equal(key, e->session_ids[i].key); 1743 if (sid_match && key_match) { 1744 debug_f("session ID already recorded for %s %s", 1745 sshkey_type(key), fp); 1746 r = 0; 1747 goto out; 1748 } else if (sid_match) { 1749 error_f("session ID recorded against different key " 1750 "for %s %s", sshkey_type(key), fp); 1751 r = -1; 1752 goto out; 1753 } 1754 /* 1755 * new sid with previously-seen key can happen, e.g. multiple 1756 * connections to the same host. 1757 */ 1758 } 1759 /* record new key/sid */ 1760 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1761 error_f("too many session IDs recorded"); 1762 goto out; 1763 } 1764 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1765 e->nsession_ids + 1, sizeof(*e->session_ids)); 1766 i = e->nsession_ids++; 1767 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1768 AGENT_MAX_SESSION_IDS); 1769 e->session_ids[i].key = key; 1770 e->session_ids[i].forwarded = fwd != 0; 1771 key = NULL; /* transferred */ 1772 /* can't transfer sid; it's refcounted and scoped to request's life */ 1773 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1774 fatal_f("sshbuf_new"); 1775 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1776 fatal_fr(r, "sshbuf_putb session ID"); 1777 /* success */ 1778 r = 0; 1779 out: 1780 free(fp); 1781 sshkey_free(key); 1782 sshbuf_free(sid); 1783 sshbuf_free(sig); 1784 return r == 0 ? 1 : 0; 1785 } 1786 1787 static void 1788 process_extension(SocketEntry *e) 1789 { 1790 int r, success = 0; 1791 char *name; 1792 1793 debug2_f("entering"); 1794 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1795 error_fr(r, "parse"); 1796 goto send; 1797 } 1798 if (strcmp(name, "session-bind@openssh.com") == 0) 1799 success = process_ext_session_bind(e); 1800 else 1801 debug_f("unsupported extension \"%s\"", name); 1802 free(name); 1803 send: 1804 send_status(e, success); 1805 } 1806 /* 1807 * dispatch incoming message. 1808 * returns 1 on success, 0 for incomplete messages or -1 on error. 1809 */ 1810 static int 1811 process_message(u_int socknum) 1812 { 1813 u_int msg_len; 1814 u_char type; 1815 const u_char *cp; 1816 int r; 1817 SocketEntry *e; 1818 1819 if (socknum >= sockets_alloc) 1820 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1821 e = &sockets[socknum]; 1822 1823 if (sshbuf_len(e->input) < 5) 1824 return 0; /* Incomplete message header. */ 1825 cp = sshbuf_ptr(e->input); 1826 msg_len = PEEK_U32(cp); 1827 if (msg_len > AGENT_MAX_LEN) { 1828 debug_f("socket %u (fd=%d) message too long %u > %u", 1829 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1830 return -1; 1831 } 1832 if (sshbuf_len(e->input) < msg_len + 4) 1833 return 0; /* Incomplete message body. */ 1834 1835 /* move the current input to e->request */ 1836 sshbuf_reset(e->request); 1837 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1838 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1839 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1840 r == SSH_ERR_STRING_TOO_LARGE) { 1841 error_fr(r, "parse"); 1842 return -1; 1843 } 1844 fatal_fr(r, "parse"); 1845 } 1846 1847 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1848 1849 /* check whether agent is locked */ 1850 if (locked && type != SSH_AGENTC_UNLOCK) { 1851 sshbuf_reset(e->request); 1852 switch (type) { 1853 case SSH2_AGENTC_REQUEST_IDENTITIES: 1854 /* send empty lists */ 1855 no_identities(e); 1856 break; 1857 default: 1858 /* send a fail message for all other request types */ 1859 send_status(e, 0); 1860 } 1861 return 1; 1862 } 1863 1864 switch (type) { 1865 case SSH_AGENTC_LOCK: 1866 case SSH_AGENTC_UNLOCK: 1867 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1868 break; 1869 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1870 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1871 break; 1872 /* ssh2 */ 1873 case SSH2_AGENTC_SIGN_REQUEST: 1874 process_sign_request2(e); 1875 break; 1876 case SSH2_AGENTC_REQUEST_IDENTITIES: 1877 process_request_identities(e); 1878 break; 1879 case SSH2_AGENTC_ADD_IDENTITY: 1880 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1881 process_add_identity(e); 1882 break; 1883 case SSH2_AGENTC_REMOVE_IDENTITY: 1884 process_remove_identity(e); 1885 break; 1886 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1887 process_remove_all_identities(e); 1888 break; 1889 #ifdef ENABLE_PKCS11 1890 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1891 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1892 process_add_smartcard_key(e); 1893 break; 1894 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1895 process_remove_smartcard_key(e); 1896 break; 1897 #endif /* ENABLE_PKCS11 */ 1898 case SSH_AGENTC_EXTENSION: 1899 process_extension(e); 1900 break; 1901 default: 1902 /* Unknown message. Respond with failure. */ 1903 error("Unknown message %d", type); 1904 sshbuf_reset(e->request); 1905 send_status(e, 0); 1906 break; 1907 } 1908 return 1; 1909 } 1910 1911 static void 1912 new_socket(sock_type type, int fd) 1913 { 1914 u_int i, old_alloc, new_alloc; 1915 1916 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1917 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1918 if (type == AUTH_CONNECTION) { 1919 debug("xcount %d -> %d", xcount, xcount + 1); 1920 ++xcount; 1921 } 1922 set_nonblock(fd); 1923 1924 if (fd > max_fd) 1925 max_fd = fd; 1926 1927 for (i = 0; i < sockets_alloc; i++) 1928 if (sockets[i].type == AUTH_UNUSED) { 1929 sockets[i].fd = fd; 1930 if ((sockets[i].input = sshbuf_new()) == NULL || 1931 (sockets[i].output = sshbuf_new()) == NULL || 1932 (sockets[i].request = sshbuf_new()) == NULL) 1933 fatal_f("sshbuf_new failed"); 1934 sockets[i].type = type; 1935 return; 1936 } 1937 old_alloc = sockets_alloc; 1938 new_alloc = sockets_alloc + 10; 1939 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1940 sizeof(sockets[0])); 1941 for (i = old_alloc; i < new_alloc; i++) 1942 sockets[i].type = AUTH_UNUSED; 1943 sockets_alloc = new_alloc; 1944 sockets[old_alloc].fd = fd; 1945 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1946 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1947 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1948 fatal_f("sshbuf_new failed"); 1949 sockets[old_alloc].type = type; 1950 } 1951 1952 static int 1953 handle_socket_read(u_int socknum) 1954 { 1955 struct sockaddr_un sunaddr; 1956 socklen_t slen; 1957 uid_t euid; 1958 gid_t egid; 1959 int fd; 1960 1961 slen = sizeof(sunaddr); 1962 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1963 if (fd == -1) { 1964 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1965 return -1; 1966 } 1967 if (getpeereid(fd, &euid, &egid) == -1) { 1968 error("getpeereid %d failed: %s", fd, strerror(errno)); 1969 close(fd); 1970 return -1; 1971 } 1972 if ((euid != 0) && (getuid() != euid)) { 1973 error("uid mismatch: peer euid %u != uid %u", 1974 (u_int) euid, (u_int) getuid()); 1975 close(fd); 1976 return -1; 1977 } 1978 new_socket(AUTH_CONNECTION, fd); 1979 return 0; 1980 } 1981 1982 static int 1983 handle_conn_read(u_int socknum) 1984 { 1985 char buf[AGENT_RBUF_LEN]; 1986 ssize_t len; 1987 int r; 1988 1989 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1990 if (len == -1) { 1991 if (errno == EAGAIN || errno == EINTR) 1992 return 0; 1993 error_f("read error on socket %u (fd %d): %s", 1994 socknum, sockets[socknum].fd, strerror(errno)); 1995 } 1996 return -1; 1997 } 1998 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1999 fatal_fr(r, "compose"); 2000 explicit_bzero(buf, sizeof(buf)); 2001 for (;;) { 2002 if ((r = process_message(socknum)) == -1) 2003 return -1; 2004 else if (r == 0) 2005 break; 2006 } 2007 return 0; 2008 } 2009 2010 static int 2011 handle_conn_write(u_int socknum) 2012 { 2013 ssize_t len; 2014 int r; 2015 2016 if (sshbuf_len(sockets[socknum].output) == 0) 2017 return 0; /* shouldn't happen */ 2018 if ((len = write(sockets[socknum].fd, 2019 sshbuf_ptr(sockets[socknum].output), 2020 sshbuf_len(sockets[socknum].output))) <= 0) { 2021 if (len == -1) { 2022 if (errno == EAGAIN || errno == EINTR) 2023 return 0; 2024 error_f("read error on socket %u (fd %d): %s", 2025 socknum, sockets[socknum].fd, strerror(errno)); 2026 } 2027 return -1; 2028 } 2029 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 2030 fatal_fr(r, "consume"); 2031 return 0; 2032 } 2033 2034 static void 2035 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 2036 { 2037 size_t i; 2038 u_int socknum, activefds = npfd; 2039 2040 for (i = 0; i < npfd; i++) { 2041 if (pfd[i].revents == 0) 2042 continue; 2043 /* Find sockets entry */ 2044 for (socknum = 0; socknum < sockets_alloc; socknum++) { 2045 if (sockets[socknum].type != AUTH_SOCKET && 2046 sockets[socknum].type != AUTH_CONNECTION) 2047 continue; 2048 if (pfd[i].fd == sockets[socknum].fd) 2049 break; 2050 } 2051 if (socknum >= sockets_alloc) { 2052 error_f("no socket for fd %d", pfd[i].fd); 2053 continue; 2054 } 2055 /* Process events */ 2056 switch (sockets[socknum].type) { 2057 case AUTH_SOCKET: 2058 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 2059 break; 2060 if (npfd > maxfds) { 2061 debug3("out of fds (active %u >= limit %u); " 2062 "skipping accept", activefds, maxfds); 2063 break; 2064 } 2065 if (handle_socket_read(socknum) == 0) 2066 activefds++; 2067 break; 2068 case AUTH_CONNECTION: 2069 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 2070 handle_conn_read(socknum) != 0) 2071 goto close_sock; 2072 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 2073 handle_conn_write(socknum) != 0) { 2074 close_sock: 2075 if (activefds == 0) 2076 fatal("activefds == 0 at close_sock"); 2077 close_socket(&sockets[socknum]); 2078 activefds--; 2079 break; 2080 } 2081 break; 2082 default: 2083 break; 2084 } 2085 } 2086 } 2087 2088 static int 2089 prepare_poll(struct pollfd **pfdp, size_t *npfdp, struct timespec *timeoutp, u_int maxfds) 2090 { 2091 struct pollfd *pfd = *pfdp; 2092 size_t i, j, npfd = 0; 2093 time_t deadline; 2094 int r; 2095 2096 /* Count active sockets */ 2097 for (i = 0; i < sockets_alloc; i++) { 2098 switch (sockets[i].type) { 2099 case AUTH_SOCKET: 2100 case AUTH_CONNECTION: 2101 npfd++; 2102 break; 2103 case AUTH_UNUSED: 2104 break; 2105 default: 2106 fatal("Unknown socket type %d", sockets[i].type); 2107 break; 2108 } 2109 } 2110 if (npfd != *npfdp && 2111 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 2112 fatal_f("recallocarray failed"); 2113 *pfdp = pfd; 2114 *npfdp = npfd; 2115 2116 for (i = j = 0; i < sockets_alloc; i++) { 2117 switch (sockets[i].type) { 2118 case AUTH_SOCKET: 2119 if (npfd > maxfds) { 2120 debug3("out of fds (active %zu >= limit %u); " 2121 "skipping arming listener", npfd, maxfds); 2122 break; 2123 } 2124 pfd[j].fd = sockets[i].fd; 2125 pfd[j].revents = 0; 2126 pfd[j].events = POLLIN; 2127 j++; 2128 break; 2129 case AUTH_CONNECTION: 2130 pfd[j].fd = sockets[i].fd; 2131 pfd[j].revents = 0; 2132 /* 2133 * Only prepare to read if we can handle a full-size 2134 * input read buffer and enqueue a max size reply.. 2135 */ 2136 if ((r = sshbuf_check_reserve(sockets[i].input, 2137 AGENT_RBUF_LEN)) == 0 && 2138 (r = sshbuf_check_reserve(sockets[i].output, 2139 AGENT_MAX_LEN)) == 0) 2140 pfd[j].events = POLLIN; 2141 else if (r != SSH_ERR_NO_BUFFER_SPACE) 2142 fatal_fr(r, "reserve"); 2143 if (sshbuf_len(sockets[i].output) > 0) 2144 pfd[j].events |= POLLOUT; 2145 j++; 2146 break; 2147 default: 2148 break; 2149 } 2150 } 2151 deadline = reaper(); 2152 if (parent_alive_interval != 0) 2153 deadline = (deadline == 0) ? parent_alive_interval : 2154 MINIMUM(deadline, parent_alive_interval); 2155 if (deadline != 0) 2156 ptimeout_deadline_sec(timeoutp, deadline); 2157 return (1); 2158 } 2159 2160 static void 2161 cleanup_socket(void) 2162 { 2163 if (cleanup_pid != 0 && getpid() != cleanup_pid) 2164 return; 2165 debug_f("cleanup"); 2166 if (socket_name[0]) 2167 unlink(socket_name); 2168 if (socket_dir[0]) 2169 rmdir(socket_dir); 2170 } 2171 2172 void 2173 cleanup_exit(int i) 2174 { 2175 cleanup_socket(); 2176 #ifdef ENABLE_PKCS11 2177 pkcs11_terminate(); 2178 #endif 2179 _exit(i); 2180 } 2181 2182 static void 2183 cleanup_handler(int sig) 2184 { 2185 signalled = sig; 2186 } 2187 2188 static void 2189 check_parent_exists(void) 2190 { 2191 /* 2192 * If our parent has exited then getppid() will return (pid_t)1, 2193 * so testing for that should be safe. 2194 */ 2195 if (parent_pid != -1 && getppid() != parent_pid) { 2196 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2197 cleanup_socket(); 2198 _exit(2); 2199 } 2200 } 2201 2202 static void 2203 usage(void) 2204 { 2205 fprintf(stderr, 2206 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2207 " [-O option] [-P allowed_providers] [-t life]\n" 2208 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2209 " [-P allowed_providers] [-t life] command [arg ...]\n" 2210 " ssh-agent [-c | -s] -k\n"); 2211 exit(1); 2212 } 2213 2214 int 2215 main(int ac, char **av) 2216 { 2217 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2218 int sock, ch, result, saved_errno; 2219 char *shell, *format, *pidstr, *agentsocket = NULL; 2220 #ifdef HAVE_SETRLIMIT 2221 struct rlimit rlim; 2222 #endif 2223 extern int optind; 2224 extern char *optarg; 2225 pid_t pid; 2226 char pidstrbuf[1 + 3 * sizeof pid]; 2227 size_t len; 2228 mode_t prev_mask; 2229 struct timespec timeout; 2230 struct pollfd *pfd = NULL; 2231 size_t npfd = 0; 2232 u_int maxfds; 2233 sigset_t nsigset, osigset; 2234 2235 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2236 sanitise_stdfd(); 2237 2238 /* drop */ 2239 (void)setegid(getgid()); 2240 (void)setgid(getgid()); 2241 setuid(geteuid()); 2242 2243 platform_disable_tracing(0); /* strict=no */ 2244 2245 #ifdef RLIMIT_NOFILE 2246 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2247 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2248 #endif 2249 2250 __progname = ssh_get_progname(av[0]); 2251 seed_rng(); 2252 2253 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2254 switch (ch) { 2255 case 'E': 2256 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2257 if (fingerprint_hash == -1) 2258 fatal("Invalid hash algorithm \"%s\"", optarg); 2259 break; 2260 case 'c': 2261 if (s_flag) 2262 usage(); 2263 c_flag++; 2264 break; 2265 case 'k': 2266 k_flag++; 2267 break; 2268 case 'O': 2269 if (strcmp(optarg, "no-restrict-websafe") == 0) 2270 restrict_websafe = 0; 2271 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2272 remote_add_provider = 1; 2273 else 2274 fatal("Unknown -O option"); 2275 break; 2276 case 'P': 2277 if (allowed_providers != NULL) 2278 fatal("-P option already specified"); 2279 allowed_providers = xstrdup(optarg); 2280 break; 2281 case 's': 2282 if (c_flag) 2283 usage(); 2284 s_flag++; 2285 break; 2286 case 'd': 2287 if (d_flag || D_flag) 2288 usage(); 2289 d_flag++; 2290 break; 2291 case 'D': 2292 if (d_flag || D_flag) 2293 usage(); 2294 D_flag++; 2295 break; 2296 case 'a': 2297 agentsocket = optarg; 2298 break; 2299 case 't': 2300 if ((lifetime = convtime(optarg)) == -1) { 2301 fprintf(stderr, "Invalid lifetime\n"); 2302 usage(); 2303 } 2304 break; 2305 case 'x': 2306 xcount = 0; 2307 break; 2308 default: 2309 usage(); 2310 } 2311 } 2312 ac -= optind; 2313 av += optind; 2314 2315 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2316 usage(); 2317 2318 if (allowed_providers == NULL) 2319 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2320 2321 if (ac == 0 && !c_flag && !s_flag) { 2322 shell = getenv("SHELL"); 2323 if (shell != NULL && (len = strlen(shell)) > 2 && 2324 strncmp(shell + len - 3, "csh", 3) == 0) 2325 c_flag = 1; 2326 } 2327 if (k_flag) { 2328 const char *errstr = NULL; 2329 2330 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2331 if (pidstr == NULL) { 2332 fprintf(stderr, "%s not set, cannot kill agent\n", 2333 SSH_AGENTPID_ENV_NAME); 2334 exit(1); 2335 } 2336 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2337 if (errstr) { 2338 fprintf(stderr, 2339 "%s=\"%s\", which is not a good PID: %s\n", 2340 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2341 exit(1); 2342 } 2343 if (kill(pid, SIGTERM) == -1) { 2344 perror("kill"); 2345 exit(1); 2346 } 2347 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2348 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2349 printf(format, SSH_AGENTPID_ENV_NAME); 2350 printf("echo Agent pid %ld killed;\n", (long)pid); 2351 exit(0); 2352 } 2353 2354 /* 2355 * Minimum file descriptors: 2356 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2357 * a few spare for libc / stack protectors / sanitisers, etc. 2358 */ 2359 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2360 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2361 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2362 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2363 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2364 2365 parent_pid = getpid(); 2366 2367 if (agentsocket == NULL) { 2368 /* Create private directory for agent socket */ 2369 mktemp_proto(socket_dir, sizeof(socket_dir)); 2370 if (mkdtemp(socket_dir) == NULL) { 2371 perror("mkdtemp: private socket dir"); 2372 exit(1); 2373 } 2374 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2375 (long)parent_pid); 2376 } else { 2377 /* Try to use specified agent socket */ 2378 socket_dir[0] = '\0'; 2379 strlcpy(socket_name, agentsocket, sizeof socket_name); 2380 } 2381 2382 /* 2383 * Create socket early so it will exist before command gets run from 2384 * the parent. 2385 */ 2386 prev_mask = umask(0177); 2387 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2388 if (sock < 0) { 2389 /* XXX - unix_listener() calls error() not perror() */ 2390 *socket_name = '\0'; /* Don't unlink any existing file */ 2391 cleanup_exit(1); 2392 } 2393 umask(prev_mask); 2394 2395 /* 2396 * Fork, and have the parent execute the command, if any, or present 2397 * the socket data. The child continues as the authentication agent. 2398 */ 2399 if (D_flag || d_flag) { 2400 log_init(__progname, 2401 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2402 SYSLOG_FACILITY_AUTH, 1); 2403 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2404 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2405 SSH_AUTHSOCKET_ENV_NAME); 2406 printf("echo Agent pid %ld;\n", (long)parent_pid); 2407 fflush(stdout); 2408 goto skip; 2409 } 2410 pid = fork(); 2411 if (pid == -1) { 2412 perror("fork"); 2413 cleanup_exit(1); 2414 } 2415 if (pid != 0) { /* Parent - execute the given command. */ 2416 close(sock); 2417 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2418 if (ac == 0) { 2419 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2420 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2421 SSH_AUTHSOCKET_ENV_NAME); 2422 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2423 SSH_AGENTPID_ENV_NAME); 2424 printf("echo Agent pid %ld;\n", (long)pid); 2425 exit(0); 2426 } 2427 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2428 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2429 perror("setenv"); 2430 exit(1); 2431 } 2432 execvp(av[0], av); 2433 perror(av[0]); 2434 exit(1); 2435 } 2436 /* child */ 2437 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2438 2439 if (setsid() == -1) { 2440 error("setsid: %s", strerror(errno)); 2441 cleanup_exit(1); 2442 } 2443 2444 (void)chdir("/"); 2445 if (stdfd_devnull(1, 1, 1) == -1) 2446 error_f("stdfd_devnull failed"); 2447 2448 #ifdef HAVE_SETRLIMIT 2449 /* deny core dumps, since memory contains unencrypted private keys */ 2450 rlim.rlim_cur = rlim.rlim_max = 0; 2451 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2452 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2453 cleanup_exit(1); 2454 } 2455 #endif 2456 2457 skip: 2458 2459 cleanup_pid = getpid(); 2460 2461 #ifdef ENABLE_PKCS11 2462 pkcs11_init(0); 2463 #endif 2464 new_socket(AUTH_SOCKET, sock); 2465 if (ac > 0) 2466 parent_alive_interval = 10; 2467 idtab_init(); 2468 ssh_signal(SIGPIPE, SIG_IGN); 2469 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2470 ssh_signal(SIGHUP, cleanup_handler); 2471 ssh_signal(SIGTERM, cleanup_handler); 2472 2473 sigemptyset(&nsigset); 2474 sigaddset(&nsigset, SIGINT); 2475 sigaddset(&nsigset, SIGHUP); 2476 sigaddset(&nsigset, SIGTERM); 2477 2478 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2479 fatal("%s: pledge: %s", __progname, strerror(errno)); 2480 platform_pledge_agent(); 2481 2482 while (1) { 2483 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 2484 if (signalled != 0) { 2485 logit("exiting on signal %d", (int)signalled); 2486 cleanup_exit(2); 2487 } 2488 ptimeout_init(&timeout); 2489 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2490 result = ppoll(pfd, npfd, ptimeout_get_tsp(&timeout), &osigset); 2491 sigprocmask(SIG_SETMASK, &osigset, NULL); 2492 saved_errno = errno; 2493 if (parent_alive_interval != 0) 2494 check_parent_exists(); 2495 (void) reaper(); /* remove expired keys */ 2496 if (result == -1) { 2497 if (saved_errno == EINTR) 2498 continue; 2499 fatal("poll: %s", strerror(saved_errno)); 2500 } else if (result > 0) 2501 after_poll(pfd, npfd, maxfds); 2502 } 2503 /* NOTREACHED */ 2504 } 2505