1 /* $OpenBSD: ssh-agent.c,v 1.303 2023/12/18 14:48:08 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 /* pid of process for which cleanup_socket is applicable */ 166 pid_t cleanup_pid = 0; 167 168 /* pathname and directory for AUTH_SOCKET */ 169 char socket_name[PATH_MAX]; 170 char socket_dir[PATH_MAX]; 171 172 /* Pattern-list of allowed PKCS#11/Security key paths */ 173 static char *allowed_providers; 174 175 /* 176 * Allows PKCS11 providers or SK keys that use non-internal providers to 177 * be added over a remote connection (identified by session-bind@openssh.com). 178 */ 179 static int remote_add_provider; 180 181 /* locking */ 182 #define LOCK_SIZE 32 183 #define LOCK_SALT_SIZE 16 184 #define LOCK_ROUNDS 1 185 int locked = 0; 186 u_char lock_pwhash[LOCK_SIZE]; 187 u_char lock_salt[LOCK_SALT_SIZE]; 188 189 extern char *__progname; 190 191 /* Default lifetime in seconds (0 == forever) */ 192 static int lifetime = 0; 193 194 static int fingerprint_hash = SSH_FP_HASH_DEFAULT; 195 196 /* Refuse signing of non-SSH messages for web-origin FIDO keys */ 197 static int restrict_websafe = 1; 198 199 /* 200 * Client connection count; incremented in new_socket() and decremented in 201 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is 202 * normally initialized to 1, it will never reach 0. However, if the -x 203 * option is specified, it is initialized to 0 in main(); in that case, 204 * ssh-agent will exit as soon as it has had at least one client but no 205 * longer has any. 206 */ 207 static int xcount = 1; 208 209 static void 210 close_socket(SocketEntry *e) 211 { 212 size_t i; 213 int last = 0; 214 215 if (e->type == AUTH_CONNECTION) { 216 debug("xcount %d -> %d", xcount, xcount - 1); 217 if (--xcount == 0) 218 last = 1; 219 } 220 close(e->fd); 221 sshbuf_free(e->input); 222 sshbuf_free(e->output); 223 sshbuf_free(e->request); 224 for (i = 0; i < e->nsession_ids; i++) { 225 sshkey_free(e->session_ids[i].key); 226 sshbuf_free(e->session_ids[i].sid); 227 } 228 free(e->session_ids); 229 memset(e, '\0', sizeof(*e)); 230 e->fd = -1; 231 e->type = AUTH_UNUSED; 232 if (last) 233 cleanup_exit(0); 234 } 235 236 static void 237 idtab_init(void) 238 { 239 idtab = xcalloc(1, sizeof(*idtab)); 240 TAILQ_INIT(&idtab->idlist); 241 idtab->nentries = 0; 242 } 243 244 static void 245 free_dest_constraint_hop(struct dest_constraint_hop *dch) 246 { 247 u_int i; 248 249 if (dch == NULL) 250 return; 251 free(dch->user); 252 free(dch->hostname); 253 for (i = 0; i < dch->nkeys; i++) 254 sshkey_free(dch->keys[i]); 255 free(dch->keys); 256 free(dch->key_is_ca); 257 } 258 259 static void 260 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) 261 { 262 size_t i; 263 264 for (i = 0; i < ndcs; i++) { 265 free_dest_constraint_hop(&dcs[i].from); 266 free_dest_constraint_hop(&dcs[i].to); 267 } 268 free(dcs); 269 } 270 271 static void 272 dup_dest_constraint_hop(const struct dest_constraint_hop *dch, 273 struct dest_constraint_hop *out) 274 { 275 u_int i; 276 int r; 277 278 out->user = dch->user == NULL ? NULL : xstrdup(dch->user); 279 out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname); 280 out->is_ca = dch->is_ca; 281 out->nkeys = dch->nkeys; 282 out->keys = out->nkeys == 0 ? NULL : 283 xcalloc(out->nkeys, sizeof(*out->keys)); 284 out->key_is_ca = out->nkeys == 0 ? NULL : 285 xcalloc(out->nkeys, sizeof(*out->key_is_ca)); 286 for (i = 0; i < dch->nkeys; i++) { 287 if (dch->keys[i] != NULL && 288 (r = sshkey_from_private(dch->keys[i], 289 &(out->keys[i]))) != 0) 290 fatal_fr(r, "copy key"); 291 out->key_is_ca[i] = dch->key_is_ca[i]; 292 } 293 } 294 295 static struct dest_constraint * 296 dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs) 297 { 298 size_t i; 299 struct dest_constraint *ret; 300 301 if (ndcs == 0) 302 return NULL; 303 ret = xcalloc(ndcs, sizeof(*ret)); 304 for (i = 0; i < ndcs; i++) { 305 dup_dest_constraint_hop(&dcs[i].from, &ret[i].from); 306 dup_dest_constraint_hop(&dcs[i].to, &ret[i].to); 307 } 308 return ret; 309 } 310 311 #ifdef DEBUG_CONSTRAINTS 312 static void 313 dump_dest_constraint_hop(const struct dest_constraint_hop *dch) 314 { 315 u_int i; 316 char *fp; 317 318 debug_f("user %s hostname %s is_ca %d nkeys %u", 319 dch->user == NULL ? "(null)" : dch->user, 320 dch->hostname == NULL ? "(null)" : dch->hostname, 321 dch->is_ca, dch->nkeys); 322 for (i = 0; i < dch->nkeys; i++) { 323 fp = NULL; 324 if (dch->keys[i] != NULL && 325 (fp = sshkey_fingerprint(dch->keys[i], 326 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) 327 fatal_f("fingerprint failed"); 328 debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys, 329 dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]), 330 dch->keys[i] == NULL ? "" : " ", 331 dch->keys[i] == NULL ? "none" : fp, 332 dch->key_is_ca[i]); 333 free(fp); 334 } 335 } 336 #endif /* DEBUG_CONSTRAINTS */ 337 338 static void 339 dump_dest_constraints(const char *context, 340 const struct dest_constraint *dcs, size_t ndcs) 341 { 342 #ifdef DEBUG_CONSTRAINTS 343 size_t i; 344 345 debug_f("%s: %zu constraints", context, ndcs); 346 for (i = 0; i < ndcs; i++) { 347 debug_f("constraint %zu / %zu: from: ", i, ndcs); 348 dump_dest_constraint_hop(&dcs[i].from); 349 debug_f("constraint %zu / %zu: to: ", i, ndcs); 350 dump_dest_constraint_hop(&dcs[i].to); 351 } 352 debug_f("done for %s", context); 353 #endif /* DEBUG_CONSTRAINTS */ 354 } 355 356 static void 357 free_identity(Identity *id) 358 { 359 sshkey_free(id->key); 360 free(id->provider); 361 free(id->comment); 362 free(id->sk_provider); 363 free_dest_constraints(id->dest_constraints, id->ndest_constraints); 364 free(id); 365 } 366 367 /* 368 * Match 'key' against the key/CA list in a destination constraint hop 369 * Returns 0 on success or -1 otherwise. 370 */ 371 static int 372 match_key_hop(const char *tag, const struct sshkey *key, 373 const struct dest_constraint_hop *dch) 374 { 375 const char *reason = NULL; 376 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; 377 u_int i; 378 char *fp; 379 380 if (key == NULL) 381 return -1; 382 /* XXX logspam */ 383 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 384 SSH_FP_DEFAULT)) == NULL) 385 fatal_f("fingerprint failed"); 386 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", 387 tag, hostname, sshkey_type(key), fp, dch->nkeys); 388 free(fp); 389 for (i = 0; i < dch->nkeys; i++) { 390 if (dch->keys[i] == NULL) 391 return -1; 392 /* XXX logspam */ 393 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, 394 SSH_FP_DEFAULT)) == NULL) 395 fatal_f("fingerprint failed"); 396 debug3_f("%s: key %u: %s%s %s", tag, i, 397 dch->key_is_ca[i] ? "CA " : "", 398 sshkey_type(dch->keys[i]), fp); 399 free(fp); 400 if (!sshkey_is_cert(key)) { 401 /* plain key */ 402 if (dch->key_is_ca[i] || 403 !sshkey_equal(key, dch->keys[i])) 404 continue; 405 return 0; 406 } 407 /* certificate */ 408 if (!dch->key_is_ca[i]) 409 continue; 410 if (key->cert == NULL || key->cert->signature_key == NULL) 411 return -1; /* shouldn't happen */ 412 if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) 413 continue; 414 if (sshkey_cert_check_host(key, hostname, 1, 415 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { 416 debug_f("cert %s / hostname %s rejected: %s", 417 key->cert->key_id, hostname, reason); 418 continue; 419 } 420 return 0; 421 } 422 return -1; 423 } 424 425 /* Check destination constraints on an identity against the hostkey/user */ 426 static int 427 permitted_by_dest_constraints(const struct sshkey *fromkey, 428 const struct sshkey *tokey, Identity *id, const char *user, 429 const char **hostnamep) 430 { 431 size_t i; 432 struct dest_constraint *d; 433 434 if (hostnamep != NULL) 435 *hostnamep = NULL; 436 for (i = 0; i < id->ndest_constraints; i++) { 437 d = id->dest_constraints + i; 438 /* XXX remove logspam */ 439 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", 440 i, d->from.user ? d->from.user : "", 441 d->from.user ? "@" : "", 442 d->from.hostname ? d->from.hostname : "(ORIGIN)", 443 d->from.nkeys, 444 d->to.user ? d->to.user : "", d->to.user ? "@" : "", 445 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); 446 447 /* Match 'from' key */ 448 if (fromkey == NULL) { 449 /* We are matching the first hop */ 450 if (d->from.hostname != NULL || d->from.nkeys != 0) 451 continue; 452 } else if (match_key_hop("from", fromkey, &d->from) != 0) 453 continue; 454 455 /* Match 'to' key */ 456 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) 457 continue; 458 459 /* Match user if specified */ 460 if (d->to.user != NULL && user != NULL && 461 !match_pattern(user, d->to.user)) 462 continue; 463 464 /* successfully matched this constraint */ 465 if (hostnamep != NULL) 466 *hostnamep = d->to.hostname; 467 debug2_f("allowed for hostname %s", 468 d->to.hostname == NULL ? "*" : d->to.hostname); 469 return 0; 470 } 471 /* no match */ 472 debug2_f("%s identity \"%s\" not permitted for this destination", 473 sshkey_type(id->key), id->comment); 474 return -1; 475 } 476 477 /* 478 * Check whether hostkeys on a SocketEntry and the optionally specified user 479 * are permitted by the destination constraints on the Identity. 480 * Returns 0 on success or -1 otherwise. 481 */ 482 static int 483 identity_permitted(Identity *id, SocketEntry *e, char *user, 484 const char **forward_hostnamep, const char **last_hostnamep) 485 { 486 size_t i; 487 const char **hp; 488 struct hostkey_sid *hks; 489 const struct sshkey *fromkey = NULL; 490 const char *test_user; 491 char *fp1, *fp2; 492 493 /* XXX remove logspam */ 494 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " 495 "%zu constraints", sshkey_type(id->key), id->comment, 496 e->nsession_ids, id->ndest_constraints); 497 if (id->ndest_constraints == 0) 498 return 0; /* unconstrained */ 499 if (e->session_bind_attempted && e->nsession_ids == 0) { 500 error_f("previous session bind failed on socket"); 501 return -1; 502 } 503 if (e->nsession_ids == 0) 504 return 0; /* local use */ 505 /* 506 * Walk through the hops recorded by session_id and try to find a 507 * constraint that satisfies each. 508 */ 509 for (i = 0; i < e->nsession_ids; i++) { 510 hks = e->session_ids + i; 511 if (hks->key == NULL) 512 fatal_f("internal error: no bound key"); 513 /* XXX remove logspam */ 514 fp1 = fp2 = NULL; 515 if (fromkey != NULL && 516 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, 517 SSH_FP_DEFAULT)) == NULL) 518 fatal_f("fingerprint failed"); 519 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, 520 SSH_FP_DEFAULT)) == NULL) 521 fatal_f("fingerprint failed"); 522 debug3_f("socketentry fd=%d, entry %zu %s, " 523 "from hostkey %s %s to user %s hostkey %s %s", 524 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", 525 fromkey ? sshkey_type(fromkey) : "(ORIGIN)", 526 fromkey ? fp1 : "", user ? user : "(ANY)", 527 sshkey_type(hks->key), fp2); 528 free(fp1); 529 free(fp2); 530 /* 531 * Record the hostnames for the initial forwarding and 532 * the final destination. 533 */ 534 hp = NULL; 535 if (i == e->nsession_ids - 1) 536 hp = last_hostnamep; 537 else if (i == 0) 538 hp = forward_hostnamep; 539 /* Special handling for final recorded binding */ 540 test_user = NULL; 541 if (i == e->nsession_ids - 1) { 542 /* Can only check user at final hop */ 543 test_user = user; 544 /* 545 * user is only presented for signature requests. 546 * If this is the case, make sure last binding is not 547 * for a forwarding. 548 */ 549 if (hks->forwarded && user != NULL) { 550 error_f("tried to sign on forwarding hop"); 551 return -1; 552 } 553 } else if (!hks->forwarded) { 554 error_f("tried to forward though signing bind"); 555 return -1; 556 } 557 if (permitted_by_dest_constraints(fromkey, hks->key, id, 558 test_user, hp) != 0) 559 return -1; 560 fromkey = hks->key; 561 } 562 /* 563 * Another special case: if the last bound session ID was for a 564 * forwarding, and this function is not being called to check a sign 565 * request (i.e. no 'user' supplied), then only permit the key if 566 * there is a permission that would allow it to be used at another 567 * destination. This hides keys that are allowed to be used to 568 * authenticate *to* a host but not permitted for *use* beyond it. 569 */ 570 hks = &e->session_ids[e->nsession_ids - 1]; 571 if (hks->forwarded && user == NULL && 572 permitted_by_dest_constraints(hks->key, NULL, id, 573 NULL, NULL) != 0) { 574 debug3_f("key permitted at host but not after"); 575 return -1; 576 } 577 578 /* success */ 579 return 0; 580 } 581 582 static int 583 socket_is_remote(SocketEntry *e) 584 { 585 return e->session_bind_attempted || (e->nsession_ids != 0); 586 } 587 588 /* return matching private key for given public key */ 589 static Identity * 590 lookup_identity(struct sshkey *key) 591 { 592 Identity *id; 593 594 TAILQ_FOREACH(id, &idtab->idlist, next) { 595 if (sshkey_equal(key, id->key)) 596 return (id); 597 } 598 return (NULL); 599 } 600 601 /* Check confirmation of keysign request */ 602 static int 603 confirm_key(Identity *id, const char *extra) 604 { 605 char *p; 606 int ret = -1; 607 608 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); 609 if (p != NULL && 610 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", 611 id->comment, p, 612 extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) 613 ret = 0; 614 free(p); 615 616 return (ret); 617 } 618 619 static void 620 send_status(SocketEntry *e, int success) 621 { 622 int r; 623 624 if ((r = sshbuf_put_u32(e->output, 1)) != 0 || 625 (r = sshbuf_put_u8(e->output, success ? 626 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) 627 fatal_fr(r, "compose"); 628 } 629 630 /* send list of supported public keys to 'client' */ 631 static void 632 process_request_identities(SocketEntry *e) 633 { 634 Identity *id; 635 struct sshbuf *msg, *keys; 636 int r; 637 u_int i = 0, nentries = 0; 638 char *fp; 639 640 debug2_f("entering"); 641 642 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) 643 fatal_f("sshbuf_new failed"); 644 TAILQ_FOREACH(id, &idtab->idlist, next) { 645 if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT, 646 SSH_FP_DEFAULT)) == NULL) 647 fatal_f("fingerprint failed"); 648 debug_f("key %u / %u: %s %s", i++, idtab->nentries, 649 sshkey_ssh_name(id->key), fp); 650 dump_dest_constraints(__func__, 651 id->dest_constraints, id->ndest_constraints); 652 free(fp); 653 /* identity not visible, don't include in response */ 654 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 655 continue; 656 if ((r = sshkey_puts_opts(id->key, keys, 657 SSHKEY_SERIALIZE_INFO)) != 0 || 658 (r = sshbuf_put_cstring(keys, id->comment)) != 0) { 659 error_fr(r, "compose key/comment"); 660 continue; 661 } 662 nentries++; 663 } 664 debug2_f("replying with %u allowed of %u available keys", 665 nentries, idtab->nentries); 666 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 667 (r = sshbuf_put_u32(msg, nentries)) != 0 || 668 (r = sshbuf_putb(msg, keys)) != 0) 669 fatal_fr(r, "compose"); 670 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 671 fatal_fr(r, "enqueue"); 672 sshbuf_free(msg); 673 sshbuf_free(keys); 674 } 675 676 677 static char * 678 agent_decode_alg(struct sshkey *key, u_int flags) 679 { 680 if (key->type == KEY_RSA) { 681 if (flags & SSH_AGENT_RSA_SHA2_256) 682 return "rsa-sha2-256"; 683 else if (flags & SSH_AGENT_RSA_SHA2_512) 684 return "rsa-sha2-512"; 685 } else if (key->type == KEY_RSA_CERT) { 686 if (flags & SSH_AGENT_RSA_SHA2_256) 687 return "rsa-sha2-256-cert-v01@openssh.com"; 688 else if (flags & SSH_AGENT_RSA_SHA2_512) 689 return "rsa-sha2-512-cert-v01@openssh.com"; 690 } 691 return NULL; 692 } 693 694 /* 695 * Attempt to parse the contents of a buffer as a SSH publickey userauth 696 * request, checking its contents for consistency and matching the embedded 697 * key against the one that is being used for signing. 698 * Note: does not modify msg buffer. 699 * Optionally extract the username, session ID and/or hostkey from the request. 700 */ 701 static int 702 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, 703 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) 704 { 705 struct sshbuf *b = NULL, *sess_id = NULL; 706 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; 707 int r; 708 u_char t, sig_follows; 709 struct sshkey *mkey = NULL, *hostkey = NULL; 710 711 if (userp != NULL) 712 *userp = NULL; 713 if (sess_idp != NULL) 714 *sess_idp = NULL; 715 if (hostkeyp != NULL) 716 *hostkeyp = NULL; 717 if ((b = sshbuf_fromb(msg)) == NULL) 718 fatal_f("sshbuf_fromb"); 719 720 /* SSH userauth request */ 721 if ((r = sshbuf_froms(b, &sess_id)) != 0) 722 goto out; 723 if (sshbuf_len(sess_id) == 0) { 724 r = SSH_ERR_INVALID_FORMAT; 725 goto out; 726 } 727 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ 728 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ 729 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ 730 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ 731 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ 732 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ 733 (r = sshkey_froms(b, &mkey)) != 0) /* key */ 734 goto out; 735 if (t != SSH2_MSG_USERAUTH_REQUEST || 736 sig_follows != 1 || 737 strcmp(service, "ssh-connection") != 0 || 738 !sshkey_equal(expected_key, mkey) || 739 sshkey_type_from_name(pkalg) != expected_key->type) { 740 r = SSH_ERR_INVALID_FORMAT; 741 goto out; 742 } 743 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { 744 if ((r = sshkey_froms(b, &hostkey)) != 0) 745 goto out; 746 } else if (strcmp(method, "publickey") != 0) { 747 r = SSH_ERR_INVALID_FORMAT; 748 goto out; 749 } 750 if (sshbuf_len(b) != 0) { 751 r = SSH_ERR_INVALID_FORMAT; 752 goto out; 753 } 754 /* success */ 755 r = 0; 756 debug3_f("well formed userauth"); 757 if (userp != NULL) { 758 *userp = user; 759 user = NULL; 760 } 761 if (sess_idp != NULL) { 762 *sess_idp = sess_id; 763 sess_id = NULL; 764 } 765 if (hostkeyp != NULL) { 766 *hostkeyp = hostkey; 767 hostkey = NULL; 768 } 769 out: 770 sshbuf_free(b); 771 sshbuf_free(sess_id); 772 free(user); 773 free(service); 774 free(method); 775 free(pkalg); 776 sshkey_free(mkey); 777 sshkey_free(hostkey); 778 return r; 779 } 780 781 /* 782 * Attempt to parse the contents of a buffer as a SSHSIG signature request. 783 * Note: does not modify buffer. 784 */ 785 static int 786 parse_sshsig_request(struct sshbuf *msg) 787 { 788 int r; 789 struct sshbuf *b; 790 791 if ((b = sshbuf_fromb(msg)) == NULL) 792 fatal_f("sshbuf_fromb"); 793 794 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || 795 (r = sshbuf_consume(b, 6)) != 0 || 796 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ 797 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ 798 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ 799 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ 800 goto out; 801 if (sshbuf_len(b) != 0) { 802 r = SSH_ERR_INVALID_FORMAT; 803 goto out; 804 } 805 /* success */ 806 r = 0; 807 out: 808 sshbuf_free(b); 809 return r; 810 } 811 812 /* 813 * This function inspects a message to be signed by a FIDO key that has a 814 * web-like application string (i.e. one that does not begin with "ssh:". 815 * It checks that the message is one of those expected for SSH operations 816 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges 817 * for the web. 818 */ 819 static int 820 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) 821 { 822 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { 823 debug_f("signed data matches public key userauth request"); 824 return 1; 825 } 826 if (parse_sshsig_request(data) == 0) { 827 debug_f("signed data matches SSHSIG signature request"); 828 return 1; 829 } 830 831 /* XXX check CA signature operation */ 832 833 error("web-origin key attempting to sign non-SSH message"); 834 return 0; 835 } 836 837 static int 838 buf_equal(const struct sshbuf *a, const struct sshbuf *b) 839 { 840 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) 841 return SSH_ERR_INVALID_ARGUMENT; 842 if (sshbuf_len(a) != sshbuf_len(b)) 843 return SSH_ERR_INVALID_FORMAT; 844 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) 845 return SSH_ERR_INVALID_FORMAT; 846 return 0; 847 } 848 849 /* ssh2 only */ 850 static void 851 process_sign_request2(SocketEntry *e) 852 { 853 u_char *signature = NULL; 854 size_t slen = 0; 855 u_int compat = 0, flags; 856 int r, ok = -1, retried = 0; 857 char *fp = NULL, *pin = NULL, *prompt = NULL; 858 char *user = NULL, *sig_dest = NULL; 859 const char *fwd_host = NULL, *dest_host = NULL; 860 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; 861 struct sshkey *key = NULL, *hostkey = NULL; 862 struct identity *id; 863 struct notifier_ctx *notifier = NULL; 864 865 debug_f("entering"); 866 867 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) 868 fatal_f("sshbuf_new failed"); 869 if ((r = sshkey_froms(e->request, &key)) != 0 || 870 (r = sshbuf_get_stringb(e->request, data)) != 0 || 871 (r = sshbuf_get_u32(e->request, &flags)) != 0) { 872 error_fr(r, "parse"); 873 goto send; 874 } 875 876 if ((id = lookup_identity(key)) == NULL) { 877 verbose_f("%s key not found", sshkey_type(key)); 878 goto send; 879 } 880 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 881 SSH_FP_DEFAULT)) == NULL) 882 fatal_f("fingerprint failed"); 883 884 if (id->ndest_constraints != 0) { 885 if (e->nsession_ids == 0) { 886 logit_f("refusing use of destination-constrained key " 887 "to sign on unbound connection"); 888 goto send; 889 } 890 if (parse_userauth_request(data, key, &user, &sid, 891 &hostkey) != 0) { 892 logit_f("refusing use of destination-constrained key " 893 "to sign an unidentified signature"); 894 goto send; 895 } 896 /* XXX logspam */ 897 debug_f("user=%s", user); 898 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) 899 goto send; 900 /* XXX display fwd_host/dest_host in askpass UI */ 901 /* 902 * Ensure that the session ID is the most recent one 903 * registered on the socket - it should have been bound by 904 * ssh immediately before userauth. 905 */ 906 if (buf_equal(sid, 907 e->session_ids[e->nsession_ids - 1].sid) != 0) { 908 error_f("unexpected session ID (%zu listed) on " 909 "signature request for target user %s with " 910 "key %s %s", e->nsession_ids, user, 911 sshkey_type(id->key), fp); 912 goto send; 913 } 914 /* 915 * Ensure that the hostkey embedded in the signature matches 916 * the one most recently bound to the socket. An exception is 917 * made for the initial forwarding hop. 918 */ 919 if (e->nsession_ids > 1 && hostkey == NULL) { 920 error_f("refusing use of destination-constrained key: " 921 "no hostkey recorded in signature for forwarded " 922 "connection"); 923 goto send; 924 } 925 if (hostkey != NULL && !sshkey_equal(hostkey, 926 e->session_ids[e->nsession_ids - 1].key)) { 927 error_f("refusing use of destination-constrained key: " 928 "mismatch between hostkey in request and most " 929 "recently bound session"); 930 goto send; 931 } 932 xasprintf(&sig_dest, "public key authentication request for " 933 "user \"%s\" to listed host", user); 934 } 935 if (id->confirm && confirm_key(id, sig_dest) != 0) { 936 verbose_f("user refused key"); 937 goto send; 938 } 939 if (sshkey_is_sk(id->key)) { 940 if (restrict_websafe && 941 strncmp(id->key->sk_application, "ssh:", 4) != 0 && 942 !check_websafe_message_contents(key, data)) { 943 /* error already logged */ 944 goto send; 945 } 946 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 947 notifier = notify_start(0, 948 "Confirm user presence for key %s %s%s%s", 949 sshkey_type(id->key), fp, 950 sig_dest == NULL ? "" : "\n", 951 sig_dest == NULL ? "" : sig_dest); 952 } 953 } 954 retry_pin: 955 if ((r = sshkey_sign(id->key, &signature, &slen, 956 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), 957 id->sk_provider, pin, compat)) != 0) { 958 debug_fr(r, "sshkey_sign"); 959 if (pin == NULL && !retried && sshkey_is_sk(id->key) && 960 r == SSH_ERR_KEY_WRONG_PASSPHRASE) { 961 notify_complete(notifier, NULL); 962 notifier = NULL; 963 /* XXX include sig_dest */ 964 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", 965 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? 966 " and confirm user presence " : " ", 967 sshkey_type(id->key), fp); 968 pin = read_passphrase(prompt, RP_USE_ASKPASS); 969 retried = 1; 970 goto retry_pin; 971 } 972 error_fr(r, "sshkey_sign"); 973 goto send; 974 } 975 /* Success */ 976 ok = 0; 977 debug_f("good signature"); 978 send: 979 notify_complete(notifier, "User presence confirmed"); 980 981 if (ok == 0) { 982 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || 983 (r = sshbuf_put_string(msg, signature, slen)) != 0) 984 fatal_fr(r, "compose"); 985 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) 986 fatal_fr(r, "compose failure"); 987 988 if ((r = sshbuf_put_stringb(e->output, msg)) != 0) 989 fatal_fr(r, "enqueue"); 990 991 sshbuf_free(sid); 992 sshbuf_free(data); 993 sshbuf_free(msg); 994 sshkey_free(key); 995 sshkey_free(hostkey); 996 free(fp); 997 free(signature); 998 free(sig_dest); 999 free(user); 1000 free(prompt); 1001 if (pin != NULL) 1002 freezero(pin, strlen(pin)); 1003 } 1004 1005 /* shared */ 1006 static void 1007 process_remove_identity(SocketEntry *e) 1008 { 1009 int r, success = 0; 1010 struct sshkey *key = NULL; 1011 Identity *id; 1012 1013 debug2_f("entering"); 1014 if ((r = sshkey_froms(e->request, &key)) != 0) { 1015 error_fr(r, "parse key"); 1016 goto done; 1017 } 1018 if ((id = lookup_identity(key)) == NULL) { 1019 debug_f("key not found"); 1020 goto done; 1021 } 1022 /* identity not visible, cannot be removed */ 1023 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1024 goto done; /* error already logged */ 1025 /* We have this key, free it. */ 1026 if (idtab->nentries < 1) 1027 fatal_f("internal error: nentries %d", idtab->nentries); 1028 TAILQ_REMOVE(&idtab->idlist, id, next); 1029 free_identity(id); 1030 idtab->nentries--; 1031 success = 1; 1032 done: 1033 sshkey_free(key); 1034 send_status(e, success); 1035 } 1036 1037 static void 1038 process_remove_all_identities(SocketEntry *e) 1039 { 1040 Identity *id; 1041 1042 debug2_f("entering"); 1043 /* Loop over all identities and clear the keys. */ 1044 for (id = TAILQ_FIRST(&idtab->idlist); id; 1045 id = TAILQ_FIRST(&idtab->idlist)) { 1046 TAILQ_REMOVE(&idtab->idlist, id, next); 1047 free_identity(id); 1048 } 1049 1050 /* Mark that there are no identities. */ 1051 idtab->nentries = 0; 1052 1053 /* Send success. */ 1054 send_status(e, 1); 1055 } 1056 1057 /* removes expired keys and returns number of seconds until the next expiry */ 1058 static time_t 1059 reaper(void) 1060 { 1061 time_t deadline = 0, now = monotime(); 1062 Identity *id, *nxt; 1063 1064 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1065 nxt = TAILQ_NEXT(id, next); 1066 if (id->death == 0) 1067 continue; 1068 if (now >= id->death) { 1069 debug("expiring key '%s'", id->comment); 1070 TAILQ_REMOVE(&idtab->idlist, id, next); 1071 free_identity(id); 1072 idtab->nentries--; 1073 } else 1074 deadline = (deadline == 0) ? id->death : 1075 MINIMUM(deadline, id->death); 1076 } 1077 if (deadline == 0 || deadline <= now) 1078 return 0; 1079 else 1080 return (deadline - now); 1081 } 1082 1083 static int 1084 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) 1085 { 1086 u_char key_is_ca; 1087 size_t elen = 0; 1088 int r; 1089 struct sshkey *k = NULL; 1090 char *fp; 1091 1092 memset(dch, '\0', sizeof(*dch)); 1093 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || 1094 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || 1095 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1096 error_fr(r, "parse"); 1097 goto out; 1098 } 1099 if (elen != 0) { 1100 error_f("unsupported extensions (len %zu)", elen); 1101 r = SSH_ERR_FEATURE_UNSUPPORTED; 1102 goto out; 1103 } 1104 if (*dch->hostname == '\0') { 1105 free(dch->hostname); 1106 dch->hostname = NULL; 1107 } 1108 if (*dch->user == '\0') { 1109 free(dch->user); 1110 dch->user = NULL; 1111 } 1112 while (sshbuf_len(b) != 0) { 1113 dch->keys = xrecallocarray(dch->keys, dch->nkeys, 1114 dch->nkeys + 1, sizeof(*dch->keys)); 1115 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, 1116 dch->nkeys + 1, sizeof(*dch->key_is_ca)); 1117 if ((r = sshkey_froms(b, &k)) != 0 || 1118 (r = sshbuf_get_u8(b, &key_is_ca)) != 0) 1119 goto out; 1120 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1121 SSH_FP_DEFAULT)) == NULL) 1122 fatal_f("fingerprint failed"); 1123 debug3_f("%s%s%s: adding %skey %s %s", 1124 dch->user == NULL ? "" : dch->user, 1125 dch->user == NULL ? "" : "@", 1126 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); 1127 free(fp); 1128 dch->keys[dch->nkeys] = k; 1129 dch->key_is_ca[dch->nkeys] = key_is_ca != 0; 1130 dch->nkeys++; 1131 k = NULL; /* transferred */ 1132 } 1133 /* success */ 1134 r = 0; 1135 out: 1136 sshkey_free(k); 1137 return r; 1138 } 1139 1140 static int 1141 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) 1142 { 1143 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; 1144 int r; 1145 size_t elen = 0; 1146 1147 debug3_f("entering"); 1148 1149 memset(dc, '\0', sizeof(*dc)); 1150 if ((r = sshbuf_froms(m, &b)) != 0 || 1151 (r = sshbuf_froms(b, &frombuf)) != 0 || 1152 (r = sshbuf_froms(b, &tobuf)) != 0 || 1153 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { 1154 error_fr(r, "parse"); 1155 goto out; 1156 } 1157 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || 1158 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) 1159 goto out; /* already logged */ 1160 if (elen != 0) { 1161 error_f("unsupported extensions (len %zu)", elen); 1162 r = SSH_ERR_FEATURE_UNSUPPORTED; 1163 goto out; 1164 } 1165 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", 1166 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, 1167 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", 1168 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); 1169 /* check consistency */ 1170 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || 1171 dc->from.user != NULL) { 1172 error_f("inconsistent \"from\" specification"); 1173 r = SSH_ERR_INVALID_FORMAT; 1174 goto out; 1175 } 1176 if (dc->to.hostname == NULL || dc->to.nkeys == 0) { 1177 error_f("incomplete \"to\" specification"); 1178 r = SSH_ERR_INVALID_FORMAT; 1179 goto out; 1180 } 1181 /* success */ 1182 r = 0; 1183 out: 1184 sshbuf_free(b); 1185 sshbuf_free(frombuf); 1186 sshbuf_free(tobuf); 1187 return r; 1188 } 1189 1190 static int 1191 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, 1192 struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp, 1193 struct sshkey ***certs, size_t *ncerts) 1194 { 1195 char *ext_name = NULL; 1196 int r; 1197 struct sshbuf *b = NULL; 1198 u_char v; 1199 struct sshkey *k; 1200 1201 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { 1202 error_fr(r, "parse constraint extension"); 1203 goto out; 1204 } 1205 debug_f("constraint ext %s", ext_name); 1206 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { 1207 if (sk_providerp == NULL) { 1208 error_f("%s not valid here", ext_name); 1209 r = SSH_ERR_INVALID_FORMAT; 1210 goto out; 1211 } 1212 if (*sk_providerp != NULL) { 1213 error_f("%s already set", ext_name); 1214 r = SSH_ERR_INVALID_FORMAT; 1215 goto out; 1216 } 1217 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { 1218 error_fr(r, "parse %s", ext_name); 1219 goto out; 1220 } 1221 } else if (strcmp(ext_name, 1222 "restrict-destination-v00@openssh.com") == 0) { 1223 if (*dcsp != NULL) { 1224 error_f("%s already set", ext_name); 1225 goto out; 1226 } 1227 if ((r = sshbuf_froms(m, &b)) != 0) { 1228 error_fr(r, "parse %s outer", ext_name); 1229 goto out; 1230 } 1231 while (sshbuf_len(b) != 0) { 1232 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { 1233 error_f("too many %s constraints", ext_name); 1234 goto out; 1235 } 1236 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, 1237 sizeof(**dcsp)); 1238 if ((r = parse_dest_constraint(b, 1239 *dcsp + (*ndcsp)++)) != 0) 1240 goto out; /* error already logged */ 1241 } 1242 } else if (strcmp(ext_name, 1243 "associated-certs-v00@openssh.com") == 0) { 1244 if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) { 1245 error_f("%s not valid here", ext_name); 1246 r = SSH_ERR_INVALID_FORMAT; 1247 goto out; 1248 } 1249 if (*certs != NULL) { 1250 error_f("%s already set", ext_name); 1251 goto out; 1252 } 1253 if ((r = sshbuf_get_u8(m, &v)) != 0 || 1254 (r = sshbuf_froms(m, &b)) != 0) { 1255 error_fr(r, "parse %s", ext_name); 1256 goto out; 1257 } 1258 *cert_onlyp = v != 0; 1259 while (sshbuf_len(b) != 0) { 1260 if (*ncerts >= AGENT_MAX_EXT_CERTS) { 1261 error_f("too many %s constraints", ext_name); 1262 goto out; 1263 } 1264 *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1, 1265 sizeof(**certs)); 1266 if ((r = sshkey_froms(b, &k)) != 0) { 1267 error_fr(r, "parse key"); 1268 goto out; 1269 } 1270 (*certs)[(*ncerts)++] = k; 1271 } 1272 } else { 1273 error_f("unsupported constraint \"%s\"", ext_name); 1274 r = SSH_ERR_FEATURE_UNSUPPORTED; 1275 goto out; 1276 } 1277 /* success */ 1278 r = 0; 1279 out: 1280 free(ext_name); 1281 sshbuf_free(b); 1282 return r; 1283 } 1284 1285 static int 1286 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, 1287 u_int *secondsp, int *confirmp, char **sk_providerp, 1288 struct dest_constraint **dcsp, size_t *ndcsp, 1289 int *cert_onlyp, size_t *ncerts, struct sshkey ***certs) 1290 { 1291 u_char ctype; 1292 int r; 1293 u_int seconds, maxsign = 0; 1294 1295 while (sshbuf_len(m)) { 1296 if ((r = sshbuf_get_u8(m, &ctype)) != 0) { 1297 error_fr(r, "parse constraint type"); 1298 goto out; 1299 } 1300 switch (ctype) { 1301 case SSH_AGENT_CONSTRAIN_LIFETIME: 1302 if (*deathp != 0) { 1303 error_f("lifetime already set"); 1304 r = SSH_ERR_INVALID_FORMAT; 1305 goto out; 1306 } 1307 if ((r = sshbuf_get_u32(m, &seconds)) != 0) { 1308 error_fr(r, "parse lifetime constraint"); 1309 goto out; 1310 } 1311 *deathp = monotime() + seconds; 1312 *secondsp = seconds; 1313 break; 1314 case SSH_AGENT_CONSTRAIN_CONFIRM: 1315 if (*confirmp != 0) { 1316 error_f("confirm already set"); 1317 r = SSH_ERR_INVALID_FORMAT; 1318 goto out; 1319 } 1320 *confirmp = 1; 1321 break; 1322 case SSH_AGENT_CONSTRAIN_MAXSIGN: 1323 if (k == NULL) { 1324 error_f("maxsign not valid here"); 1325 r = SSH_ERR_INVALID_FORMAT; 1326 goto out; 1327 } 1328 if (maxsign != 0) { 1329 error_f("maxsign already set"); 1330 r = SSH_ERR_INVALID_FORMAT; 1331 goto out; 1332 } 1333 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { 1334 error_fr(r, "parse maxsign constraint"); 1335 goto out; 1336 } 1337 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { 1338 error_fr(r, "enable maxsign"); 1339 goto out; 1340 } 1341 break; 1342 case SSH_AGENT_CONSTRAIN_EXTENSION: 1343 if ((r = parse_key_constraint_extension(m, 1344 sk_providerp, dcsp, ndcsp, 1345 cert_onlyp, certs, ncerts)) != 0) 1346 goto out; /* error already logged */ 1347 break; 1348 default: 1349 error_f("Unknown constraint %d", ctype); 1350 r = SSH_ERR_FEATURE_UNSUPPORTED; 1351 goto out; 1352 } 1353 } 1354 /* success */ 1355 r = 0; 1356 out: 1357 return r; 1358 } 1359 1360 static void 1361 process_add_identity(SocketEntry *e) 1362 { 1363 Identity *id; 1364 int success = 0, confirm = 0; 1365 char *fp, *comment = NULL, *sk_provider = NULL; 1366 char canonical_provider[PATH_MAX]; 1367 time_t death = 0; 1368 u_int seconds = 0; 1369 struct dest_constraint *dest_constraints = NULL; 1370 size_t ndest_constraints = 0; 1371 struct sshkey *k = NULL; 1372 int r = SSH_ERR_INTERNAL_ERROR; 1373 1374 debug2_f("entering"); 1375 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || 1376 k == NULL || 1377 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { 1378 error_fr(r, "parse"); 1379 goto out; 1380 } 1381 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, 1382 &sk_provider, &dest_constraints, &ndest_constraints, 1383 NULL, NULL, NULL) != 0) { 1384 error_f("failed to parse constraints"); 1385 sshbuf_reset(e->request); 1386 goto out; 1387 } 1388 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1389 1390 if (sk_provider != NULL) { 1391 if (!sshkey_is_sk(k)) { 1392 error("Cannot add provider: %s is not an " 1393 "authenticator-hosted key", sshkey_type(k)); 1394 goto out; 1395 } 1396 if (strcasecmp(sk_provider, "internal") == 0) { 1397 debug_f("internal provider"); 1398 } else { 1399 if (socket_is_remote(e) && !remote_add_provider) { 1400 verbose("failed add of SK provider \"%.100s\": " 1401 "remote addition of providers is disabled", 1402 sk_provider); 1403 goto out; 1404 } 1405 if (realpath(sk_provider, canonical_provider) == NULL) { 1406 verbose("failed provider \"%.100s\": " 1407 "realpath: %s", sk_provider, 1408 strerror(errno)); 1409 goto out; 1410 } 1411 free(sk_provider); 1412 sk_provider = xstrdup(canonical_provider); 1413 if (match_pattern_list(sk_provider, 1414 allowed_providers, 0) != 1) { 1415 error("Refusing add key: " 1416 "provider %s not allowed", sk_provider); 1417 goto out; 1418 } 1419 } 1420 } 1421 if ((r = sshkey_shield_private(k)) != 0) { 1422 error_fr(r, "shield private"); 1423 goto out; 1424 } 1425 if (lifetime && !death) 1426 death = monotime() + lifetime; 1427 if ((id = lookup_identity(k)) == NULL) { 1428 id = xcalloc(1, sizeof(Identity)); 1429 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1430 /* Increment the number of identities. */ 1431 idtab->nentries++; 1432 } else { 1433 /* identity not visible, do not update */ 1434 if (identity_permitted(id, e, NULL, NULL, NULL) != 0) 1435 goto out; /* error already logged */ 1436 /* key state might have been updated */ 1437 sshkey_free(id->key); 1438 free(id->comment); 1439 free(id->sk_provider); 1440 free_dest_constraints(id->dest_constraints, 1441 id->ndest_constraints); 1442 } 1443 /* success */ 1444 id->key = k; 1445 id->comment = comment; 1446 id->death = death; 1447 id->confirm = confirm; 1448 id->sk_provider = sk_provider; 1449 id->dest_constraints = dest_constraints; 1450 id->ndest_constraints = ndest_constraints; 1451 1452 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, 1453 SSH_FP_DEFAULT)) == NULL) 1454 fatal_f("sshkey_fingerprint failed"); 1455 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " 1456 "(provider: %s) (destination constraints: %zu)", 1457 sshkey_ssh_name(k), fp, comment, seconds, confirm, 1458 sk_provider == NULL ? "none" : sk_provider, ndest_constraints); 1459 free(fp); 1460 /* transferred */ 1461 k = NULL; 1462 comment = NULL; 1463 sk_provider = NULL; 1464 dest_constraints = NULL; 1465 ndest_constraints = 0; 1466 success = 1; 1467 out: 1468 free(sk_provider); 1469 free(comment); 1470 sshkey_free(k); 1471 free_dest_constraints(dest_constraints, ndest_constraints); 1472 send_status(e, success); 1473 } 1474 1475 /* XXX todo: encrypt sensitive data with passphrase */ 1476 static void 1477 process_lock_agent(SocketEntry *e, int lock) 1478 { 1479 int r, success = 0, delay; 1480 char *passwd; 1481 u_char passwdhash[LOCK_SIZE]; 1482 static u_int fail_count = 0; 1483 size_t pwlen; 1484 1485 debug2_f("entering"); 1486 /* 1487 * This is deliberately fatal: the user has requested that we lock, 1488 * but we can't parse their request properly. The only safe thing to 1489 * do is abort. 1490 */ 1491 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) 1492 fatal_fr(r, "parse"); 1493 if (pwlen == 0) { 1494 debug("empty password not supported"); 1495 } else if (locked && !lock) { 1496 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1497 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) 1498 fatal("bcrypt_pbkdf"); 1499 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { 1500 debug("agent unlocked"); 1501 locked = 0; 1502 fail_count = 0; 1503 explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); 1504 success = 1; 1505 } else { 1506 /* delay in 0.1s increments up to 10s */ 1507 if (fail_count < 100) 1508 fail_count++; 1509 delay = 100000 * fail_count; 1510 debug("unlock failed, delaying %0.1lf seconds", 1511 (double)delay/1000000); 1512 usleep(delay); 1513 } 1514 explicit_bzero(passwdhash, sizeof(passwdhash)); 1515 } else if (!locked && lock) { 1516 debug("agent locked"); 1517 locked = 1; 1518 arc4random_buf(lock_salt, sizeof(lock_salt)); 1519 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), 1520 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) 1521 fatal("bcrypt_pbkdf"); 1522 success = 1; 1523 } 1524 freezero(passwd, pwlen); 1525 send_status(e, success); 1526 } 1527 1528 static void 1529 no_identities(SocketEntry *e) 1530 { 1531 struct sshbuf *msg; 1532 int r; 1533 1534 if ((msg = sshbuf_new()) == NULL) 1535 fatal_f("sshbuf_new failed"); 1536 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || 1537 (r = sshbuf_put_u32(msg, 0)) != 0 || 1538 (r = sshbuf_put_stringb(e->output, msg)) != 0) 1539 fatal_fr(r, "compose"); 1540 sshbuf_free(msg); 1541 } 1542 1543 /* Add an identity to idlist; takes ownership of 'key' and 'comment' */ 1544 static void 1545 add_p11_identity(struct sshkey *key, char *comment, const char *provider, 1546 time_t death, int confirm, struct dest_constraint *dest_constraints, 1547 size_t ndest_constraints) 1548 { 1549 Identity *id; 1550 1551 if (lookup_identity(key) != NULL) { 1552 sshkey_free(key); 1553 free(comment); 1554 return; 1555 } 1556 id = xcalloc(1, sizeof(Identity)); 1557 id->key = key; 1558 id->comment = comment; 1559 id->provider = xstrdup(provider); 1560 id->death = death; 1561 id->confirm = confirm; 1562 id->dest_constraints = dup_dest_constraints(dest_constraints, 1563 ndest_constraints); 1564 id->ndest_constraints = ndest_constraints; 1565 TAILQ_INSERT_TAIL(&idtab->idlist, id, next); 1566 idtab->nentries++; 1567 } 1568 1569 #ifdef ENABLE_PKCS11 1570 static void 1571 process_add_smartcard_key(SocketEntry *e) 1572 { 1573 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1574 char **comments = NULL; 1575 int r, i, count = 0, success = 0, confirm = 0; 1576 u_int seconds = 0; 1577 time_t death = 0; 1578 struct sshkey **keys = NULL, *k; 1579 struct dest_constraint *dest_constraints = NULL; 1580 size_t j, ndest_constraints = 0, ncerts = 0; 1581 struct sshkey **certs = NULL; 1582 int cert_only = 0; 1583 1584 debug2_f("entering"); 1585 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1586 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1587 error_fr(r, "parse"); 1588 goto send; 1589 } 1590 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, 1591 NULL, &dest_constraints, &ndest_constraints, &cert_only, 1592 &ncerts, &certs) != 0) { 1593 error_f("failed to parse constraints"); 1594 goto send; 1595 } 1596 dump_dest_constraints(__func__, dest_constraints, ndest_constraints); 1597 if (socket_is_remote(e) && !remote_add_provider) { 1598 verbose("failed PKCS#11 add of \"%.100s\": remote addition of " 1599 "providers is disabled", provider); 1600 goto send; 1601 } 1602 if (realpath(provider, canonical_provider) == NULL) { 1603 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1604 provider, strerror(errno)); 1605 goto send; 1606 } 1607 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { 1608 verbose("refusing PKCS#11 add of \"%.100s\": " 1609 "provider not allowed", canonical_provider); 1610 goto send; 1611 } 1612 debug_f("add %.100s", canonical_provider); 1613 if (lifetime && !death) 1614 death = monotime() + lifetime; 1615 1616 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); 1617 for (i = 0; i < count; i++) { 1618 if (comments[i] == NULL || comments[i][0] == '\0') { 1619 free(comments[i]); 1620 comments[i] = xstrdup(canonical_provider); 1621 } 1622 for (j = 0; j < ncerts; j++) { 1623 if (!sshkey_is_cert(certs[j])) 1624 continue; 1625 if (!sshkey_equal_public(keys[i], certs[j])) 1626 continue; 1627 if (pkcs11_make_cert(keys[i], certs[j], &k) != 0) 1628 continue; 1629 add_p11_identity(k, xstrdup(comments[i]), 1630 canonical_provider, death, confirm, 1631 dest_constraints, ndest_constraints); 1632 success = 1; 1633 } 1634 if (!cert_only && lookup_identity(keys[i]) == NULL) { 1635 add_p11_identity(keys[i], comments[i], 1636 canonical_provider, death, confirm, 1637 dest_constraints, ndest_constraints); 1638 keys[i] = NULL; /* transferred */ 1639 comments[i] = NULL; /* transferred */ 1640 success = 1; 1641 } 1642 /* XXX update constraints for existing keys */ 1643 sshkey_free(keys[i]); 1644 free(comments[i]); 1645 } 1646 send: 1647 free(pin); 1648 free(provider); 1649 free(keys); 1650 free(comments); 1651 free_dest_constraints(dest_constraints, ndest_constraints); 1652 for (j = 0; j < ncerts; j++) 1653 sshkey_free(certs[j]); 1654 free(certs); 1655 send_status(e, success); 1656 } 1657 1658 static void 1659 process_remove_smartcard_key(SocketEntry *e) 1660 { 1661 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; 1662 int r, success = 0; 1663 Identity *id, *nxt; 1664 1665 debug2_f("entering"); 1666 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || 1667 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { 1668 error_fr(r, "parse"); 1669 goto send; 1670 } 1671 free(pin); 1672 1673 if (realpath(provider, canonical_provider) == NULL) { 1674 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", 1675 provider, strerror(errno)); 1676 goto send; 1677 } 1678 1679 debug_f("remove %.100s", canonical_provider); 1680 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { 1681 nxt = TAILQ_NEXT(id, next); 1682 /* Skip file--based keys */ 1683 if (id->provider == NULL) 1684 continue; 1685 if (!strcmp(canonical_provider, id->provider)) { 1686 TAILQ_REMOVE(&idtab->idlist, id, next); 1687 free_identity(id); 1688 idtab->nentries--; 1689 } 1690 } 1691 if (pkcs11_del_provider(canonical_provider) == 0) 1692 success = 1; 1693 else 1694 error_f("pkcs11_del_provider failed"); 1695 send: 1696 free(provider); 1697 send_status(e, success); 1698 } 1699 #endif /* ENABLE_PKCS11 */ 1700 1701 static int 1702 process_ext_session_bind(SocketEntry *e) 1703 { 1704 int r, sid_match, key_match; 1705 struct sshkey *key = NULL; 1706 struct sshbuf *sid = NULL, *sig = NULL; 1707 char *fp = NULL; 1708 size_t i; 1709 u_char fwd = 0; 1710 1711 debug2_f("entering"); 1712 e->session_bind_attempted = 1; 1713 if ((r = sshkey_froms(e->request, &key)) != 0 || 1714 (r = sshbuf_froms(e->request, &sid)) != 0 || 1715 (r = sshbuf_froms(e->request, &sig)) != 0 || 1716 (r = sshbuf_get_u8(e->request, &fwd)) != 0) { 1717 error_fr(r, "parse"); 1718 goto out; 1719 } 1720 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, 1721 SSH_FP_DEFAULT)) == NULL) 1722 fatal_f("fingerprint failed"); 1723 /* check signature with hostkey on session ID */ 1724 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), 1725 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { 1726 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); 1727 goto out; 1728 } 1729 /* check whether sid/key already recorded */ 1730 for (i = 0; i < e->nsession_ids; i++) { 1731 if (!e->session_ids[i].forwarded) { 1732 error_f("attempt to bind session ID to socket " 1733 "previously bound for authentication attempt"); 1734 r = -1; 1735 goto out; 1736 } 1737 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; 1738 key_match = sshkey_equal(key, e->session_ids[i].key); 1739 if (sid_match && key_match) { 1740 debug_f("session ID already recorded for %s %s", 1741 sshkey_type(key), fp); 1742 r = 0; 1743 goto out; 1744 } else if (sid_match) { 1745 error_f("session ID recorded against different key " 1746 "for %s %s", sshkey_type(key), fp); 1747 r = -1; 1748 goto out; 1749 } 1750 /* 1751 * new sid with previously-seen key can happen, e.g. multiple 1752 * connections to the same host. 1753 */ 1754 } 1755 /* record new key/sid */ 1756 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { 1757 error_f("too many session IDs recorded"); 1758 goto out; 1759 } 1760 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, 1761 e->nsession_ids + 1, sizeof(*e->session_ids)); 1762 i = e->nsession_ids++; 1763 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, 1764 AGENT_MAX_SESSION_IDS); 1765 e->session_ids[i].key = key; 1766 e->session_ids[i].forwarded = fwd != 0; 1767 key = NULL; /* transferred */ 1768 /* can't transfer sid; it's refcounted and scoped to request's life */ 1769 if ((e->session_ids[i].sid = sshbuf_new()) == NULL) 1770 fatal_f("sshbuf_new"); 1771 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) 1772 fatal_fr(r, "sshbuf_putb session ID"); 1773 /* success */ 1774 r = 0; 1775 out: 1776 free(fp); 1777 sshkey_free(key); 1778 sshbuf_free(sid); 1779 sshbuf_free(sig); 1780 return r == 0 ? 1 : 0; 1781 } 1782 1783 static void 1784 process_extension(SocketEntry *e) 1785 { 1786 int r, success = 0; 1787 char *name; 1788 1789 debug2_f("entering"); 1790 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { 1791 error_fr(r, "parse"); 1792 goto send; 1793 } 1794 if (strcmp(name, "session-bind@openssh.com") == 0) 1795 success = process_ext_session_bind(e); 1796 else 1797 debug_f("unsupported extension \"%s\"", name); 1798 free(name); 1799 send: 1800 send_status(e, success); 1801 } 1802 /* 1803 * dispatch incoming message. 1804 * returns 1 on success, 0 for incomplete messages or -1 on error. 1805 */ 1806 static int 1807 process_message(u_int socknum) 1808 { 1809 u_int msg_len; 1810 u_char type; 1811 const u_char *cp; 1812 int r; 1813 SocketEntry *e; 1814 1815 if (socknum >= sockets_alloc) 1816 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); 1817 e = &sockets[socknum]; 1818 1819 if (sshbuf_len(e->input) < 5) 1820 return 0; /* Incomplete message header. */ 1821 cp = sshbuf_ptr(e->input); 1822 msg_len = PEEK_U32(cp); 1823 if (msg_len > AGENT_MAX_LEN) { 1824 debug_f("socket %u (fd=%d) message too long %u > %u", 1825 socknum, e->fd, msg_len, AGENT_MAX_LEN); 1826 return -1; 1827 } 1828 if (sshbuf_len(e->input) < msg_len + 4) 1829 return 0; /* Incomplete message body. */ 1830 1831 /* move the current input to e->request */ 1832 sshbuf_reset(e->request); 1833 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || 1834 (r = sshbuf_get_u8(e->request, &type)) != 0) { 1835 if (r == SSH_ERR_MESSAGE_INCOMPLETE || 1836 r == SSH_ERR_STRING_TOO_LARGE) { 1837 error_fr(r, "parse"); 1838 return -1; 1839 } 1840 fatal_fr(r, "parse"); 1841 } 1842 1843 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); 1844 1845 /* check whether agent is locked */ 1846 if (locked && type != SSH_AGENTC_UNLOCK) { 1847 sshbuf_reset(e->request); 1848 switch (type) { 1849 case SSH2_AGENTC_REQUEST_IDENTITIES: 1850 /* send empty lists */ 1851 no_identities(e); 1852 break; 1853 default: 1854 /* send a fail message for all other request types */ 1855 send_status(e, 0); 1856 } 1857 return 1; 1858 } 1859 1860 switch (type) { 1861 case SSH_AGENTC_LOCK: 1862 case SSH_AGENTC_UNLOCK: 1863 process_lock_agent(e, type == SSH_AGENTC_LOCK); 1864 break; 1865 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: 1866 process_remove_all_identities(e); /* safe for !WITH_SSH1 */ 1867 break; 1868 /* ssh2 */ 1869 case SSH2_AGENTC_SIGN_REQUEST: 1870 process_sign_request2(e); 1871 break; 1872 case SSH2_AGENTC_REQUEST_IDENTITIES: 1873 process_request_identities(e); 1874 break; 1875 case SSH2_AGENTC_ADD_IDENTITY: 1876 case SSH2_AGENTC_ADD_ID_CONSTRAINED: 1877 process_add_identity(e); 1878 break; 1879 case SSH2_AGENTC_REMOVE_IDENTITY: 1880 process_remove_identity(e); 1881 break; 1882 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: 1883 process_remove_all_identities(e); 1884 break; 1885 #ifdef ENABLE_PKCS11 1886 case SSH_AGENTC_ADD_SMARTCARD_KEY: 1887 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: 1888 process_add_smartcard_key(e); 1889 break; 1890 case SSH_AGENTC_REMOVE_SMARTCARD_KEY: 1891 process_remove_smartcard_key(e); 1892 break; 1893 #endif /* ENABLE_PKCS11 */ 1894 case SSH_AGENTC_EXTENSION: 1895 process_extension(e); 1896 break; 1897 default: 1898 /* Unknown message. Respond with failure. */ 1899 error("Unknown message %d", type); 1900 sshbuf_reset(e->request); 1901 send_status(e, 0); 1902 break; 1903 } 1904 return 1; 1905 } 1906 1907 static void 1908 new_socket(sock_type type, int fd) 1909 { 1910 u_int i, old_alloc, new_alloc; 1911 1912 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : 1913 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); 1914 if (type == AUTH_CONNECTION) { 1915 debug("xcount %d -> %d", xcount, xcount + 1); 1916 ++xcount; 1917 } 1918 set_nonblock(fd); 1919 1920 if (fd > max_fd) 1921 max_fd = fd; 1922 1923 for (i = 0; i < sockets_alloc; i++) 1924 if (sockets[i].type == AUTH_UNUSED) { 1925 sockets[i].fd = fd; 1926 if ((sockets[i].input = sshbuf_new()) == NULL || 1927 (sockets[i].output = sshbuf_new()) == NULL || 1928 (sockets[i].request = sshbuf_new()) == NULL) 1929 fatal_f("sshbuf_new failed"); 1930 sockets[i].type = type; 1931 return; 1932 } 1933 old_alloc = sockets_alloc; 1934 new_alloc = sockets_alloc + 10; 1935 sockets = xrecallocarray(sockets, old_alloc, new_alloc, 1936 sizeof(sockets[0])); 1937 for (i = old_alloc; i < new_alloc; i++) 1938 sockets[i].type = AUTH_UNUSED; 1939 sockets_alloc = new_alloc; 1940 sockets[old_alloc].fd = fd; 1941 if ((sockets[old_alloc].input = sshbuf_new()) == NULL || 1942 (sockets[old_alloc].output = sshbuf_new()) == NULL || 1943 (sockets[old_alloc].request = sshbuf_new()) == NULL) 1944 fatal_f("sshbuf_new failed"); 1945 sockets[old_alloc].type = type; 1946 } 1947 1948 static int 1949 handle_socket_read(u_int socknum) 1950 { 1951 struct sockaddr_un sunaddr; 1952 socklen_t slen; 1953 uid_t euid; 1954 gid_t egid; 1955 int fd; 1956 1957 slen = sizeof(sunaddr); 1958 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); 1959 if (fd == -1) { 1960 error("accept from AUTH_SOCKET: %s", strerror(errno)); 1961 return -1; 1962 } 1963 if (getpeereid(fd, &euid, &egid) == -1) { 1964 error("getpeereid %d failed: %s", fd, strerror(errno)); 1965 close(fd); 1966 return -1; 1967 } 1968 if ((euid != 0) && (getuid() != euid)) { 1969 error("uid mismatch: peer euid %u != uid %u", 1970 (u_int) euid, (u_int) getuid()); 1971 close(fd); 1972 return -1; 1973 } 1974 new_socket(AUTH_CONNECTION, fd); 1975 return 0; 1976 } 1977 1978 static int 1979 handle_conn_read(u_int socknum) 1980 { 1981 char buf[AGENT_RBUF_LEN]; 1982 ssize_t len; 1983 int r; 1984 1985 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { 1986 if (len == -1) { 1987 if (errno == EAGAIN || errno == EINTR) 1988 return 0; 1989 error_f("read error on socket %u (fd %d): %s", 1990 socknum, sockets[socknum].fd, strerror(errno)); 1991 } 1992 return -1; 1993 } 1994 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) 1995 fatal_fr(r, "compose"); 1996 explicit_bzero(buf, sizeof(buf)); 1997 for (;;) { 1998 if ((r = process_message(socknum)) == -1) 1999 return -1; 2000 else if (r == 0) 2001 break; 2002 } 2003 return 0; 2004 } 2005 2006 static int 2007 handle_conn_write(u_int socknum) 2008 { 2009 ssize_t len; 2010 int r; 2011 2012 if (sshbuf_len(sockets[socknum].output) == 0) 2013 return 0; /* shouldn't happen */ 2014 if ((len = write(sockets[socknum].fd, 2015 sshbuf_ptr(sockets[socknum].output), 2016 sshbuf_len(sockets[socknum].output))) <= 0) { 2017 if (len == -1) { 2018 if (errno == EAGAIN || errno == EINTR) 2019 return 0; 2020 error_f("read error on socket %u (fd %d): %s", 2021 socknum, sockets[socknum].fd, strerror(errno)); 2022 } 2023 return -1; 2024 } 2025 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) 2026 fatal_fr(r, "consume"); 2027 return 0; 2028 } 2029 2030 static void 2031 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) 2032 { 2033 size_t i; 2034 u_int socknum, activefds = npfd; 2035 2036 for (i = 0; i < npfd; i++) { 2037 if (pfd[i].revents == 0) 2038 continue; 2039 /* Find sockets entry */ 2040 for (socknum = 0; socknum < sockets_alloc; socknum++) { 2041 if (sockets[socknum].type != AUTH_SOCKET && 2042 sockets[socknum].type != AUTH_CONNECTION) 2043 continue; 2044 if (pfd[i].fd == sockets[socknum].fd) 2045 break; 2046 } 2047 if (socknum >= sockets_alloc) { 2048 error_f("no socket for fd %d", pfd[i].fd); 2049 continue; 2050 } 2051 /* Process events */ 2052 switch (sockets[socknum].type) { 2053 case AUTH_SOCKET: 2054 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) 2055 break; 2056 if (npfd > maxfds) { 2057 debug3("out of fds (active %u >= limit %u); " 2058 "skipping accept", activefds, maxfds); 2059 break; 2060 } 2061 if (handle_socket_read(socknum) == 0) 2062 activefds++; 2063 break; 2064 case AUTH_CONNECTION: 2065 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && 2066 handle_conn_read(socknum) != 0) 2067 goto close_sock; 2068 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && 2069 handle_conn_write(socknum) != 0) { 2070 close_sock: 2071 if (activefds == 0) 2072 fatal("activefds == 0 at close_sock"); 2073 close_socket(&sockets[socknum]); 2074 activefds--; 2075 break; 2076 } 2077 break; 2078 default: 2079 break; 2080 } 2081 } 2082 } 2083 2084 static int 2085 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) 2086 { 2087 struct pollfd *pfd = *pfdp; 2088 size_t i, j, npfd = 0; 2089 time_t deadline; 2090 int r; 2091 2092 /* Count active sockets */ 2093 for (i = 0; i < sockets_alloc; i++) { 2094 switch (sockets[i].type) { 2095 case AUTH_SOCKET: 2096 case AUTH_CONNECTION: 2097 npfd++; 2098 break; 2099 case AUTH_UNUSED: 2100 break; 2101 default: 2102 fatal("Unknown socket type %d", sockets[i].type); 2103 break; 2104 } 2105 } 2106 if (npfd != *npfdp && 2107 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) 2108 fatal_f("recallocarray failed"); 2109 *pfdp = pfd; 2110 *npfdp = npfd; 2111 2112 for (i = j = 0; i < sockets_alloc; i++) { 2113 switch (sockets[i].type) { 2114 case AUTH_SOCKET: 2115 if (npfd > maxfds) { 2116 debug3("out of fds (active %zu >= limit %u); " 2117 "skipping arming listener", npfd, maxfds); 2118 break; 2119 } 2120 pfd[j].fd = sockets[i].fd; 2121 pfd[j].revents = 0; 2122 pfd[j].events = POLLIN; 2123 j++; 2124 break; 2125 case AUTH_CONNECTION: 2126 pfd[j].fd = sockets[i].fd; 2127 pfd[j].revents = 0; 2128 /* 2129 * Only prepare to read if we can handle a full-size 2130 * input read buffer and enqueue a max size reply.. 2131 */ 2132 if ((r = sshbuf_check_reserve(sockets[i].input, 2133 AGENT_RBUF_LEN)) == 0 && 2134 (r = sshbuf_check_reserve(sockets[i].output, 2135 AGENT_MAX_LEN)) == 0) 2136 pfd[j].events = POLLIN; 2137 else if (r != SSH_ERR_NO_BUFFER_SPACE) 2138 fatal_fr(r, "reserve"); 2139 if (sshbuf_len(sockets[i].output) > 0) 2140 pfd[j].events |= POLLOUT; 2141 j++; 2142 break; 2143 default: 2144 break; 2145 } 2146 } 2147 deadline = reaper(); 2148 if (parent_alive_interval != 0) 2149 deadline = (deadline == 0) ? parent_alive_interval : 2150 MINIMUM(deadline, parent_alive_interval); 2151 if (deadline == 0) { 2152 *timeoutp = -1; /* INFTIM */ 2153 } else { 2154 if (deadline > INT_MAX / 1000) 2155 *timeoutp = INT_MAX / 1000; 2156 else 2157 *timeoutp = deadline * 1000; 2158 } 2159 return (1); 2160 } 2161 2162 static void 2163 cleanup_socket(void) 2164 { 2165 if (cleanup_pid != 0 && getpid() != cleanup_pid) 2166 return; 2167 debug_f("cleanup"); 2168 if (socket_name[0]) 2169 unlink(socket_name); 2170 if (socket_dir[0]) 2171 rmdir(socket_dir); 2172 } 2173 2174 void 2175 cleanup_exit(int i) 2176 { 2177 cleanup_socket(); 2178 _exit(i); 2179 } 2180 2181 static void 2182 cleanup_handler(int sig) 2183 { 2184 cleanup_socket(); 2185 #ifdef ENABLE_PKCS11 2186 pkcs11_terminate(); 2187 #endif 2188 _exit(2); 2189 } 2190 2191 static void 2192 check_parent_exists(void) 2193 { 2194 /* 2195 * If our parent has exited then getppid() will return (pid_t)1, 2196 * so testing for that should be safe. 2197 */ 2198 if (parent_pid != -1 && getppid() != parent_pid) { 2199 /* printf("Parent has died - Authentication agent exiting.\n"); */ 2200 cleanup_socket(); 2201 _exit(2); 2202 } 2203 } 2204 2205 static void 2206 usage(void) 2207 { 2208 fprintf(stderr, 2209 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n" 2210 " [-O option] [-P allowed_providers] [-t life]\n" 2211 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" 2212 " [-P allowed_providers] [-t life] command [arg ...]\n" 2213 " ssh-agent [-c | -s] -k\n"); 2214 exit(1); 2215 } 2216 2217 int 2218 main(int ac, char **av) 2219 { 2220 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; 2221 int sock, ch, result, saved_errno; 2222 char *shell, *format, *pidstr, *agentsocket = NULL; 2223 #ifdef HAVE_SETRLIMIT 2224 struct rlimit rlim; 2225 #endif 2226 extern int optind; 2227 extern char *optarg; 2228 pid_t pid; 2229 char pidstrbuf[1 + 3 * sizeof pid]; 2230 size_t len; 2231 mode_t prev_mask; 2232 int timeout = -1; /* INFTIM */ 2233 struct pollfd *pfd = NULL; 2234 size_t npfd = 0; 2235 u_int maxfds; 2236 2237 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 2238 sanitise_stdfd(); 2239 2240 /* drop */ 2241 (void)setegid(getgid()); 2242 (void)setgid(getgid()); 2243 setuid(geteuid()); 2244 2245 platform_disable_tracing(0); /* strict=no */ 2246 2247 #ifdef RLIMIT_NOFILE 2248 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) 2249 fatal("%s: getrlimit: %s", __progname, strerror(errno)); 2250 #endif 2251 2252 __progname = ssh_get_progname(av[0]); 2253 seed_rng(); 2254 2255 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) { 2256 switch (ch) { 2257 case 'E': 2258 fingerprint_hash = ssh_digest_alg_by_name(optarg); 2259 if (fingerprint_hash == -1) 2260 fatal("Invalid hash algorithm \"%s\"", optarg); 2261 break; 2262 case 'c': 2263 if (s_flag) 2264 usage(); 2265 c_flag++; 2266 break; 2267 case 'k': 2268 k_flag++; 2269 break; 2270 case 'O': 2271 if (strcmp(optarg, "no-restrict-websafe") == 0) 2272 restrict_websafe = 0; 2273 else if (strcmp(optarg, "allow-remote-pkcs11") == 0) 2274 remote_add_provider = 1; 2275 else 2276 fatal("Unknown -O option"); 2277 break; 2278 case 'P': 2279 if (allowed_providers != NULL) 2280 fatal("-P option already specified"); 2281 allowed_providers = xstrdup(optarg); 2282 break; 2283 case 's': 2284 if (c_flag) 2285 usage(); 2286 s_flag++; 2287 break; 2288 case 'd': 2289 if (d_flag || D_flag) 2290 usage(); 2291 d_flag++; 2292 break; 2293 case 'D': 2294 if (d_flag || D_flag) 2295 usage(); 2296 D_flag++; 2297 break; 2298 case 'a': 2299 agentsocket = optarg; 2300 break; 2301 case 't': 2302 if ((lifetime = convtime(optarg)) == -1) { 2303 fprintf(stderr, "Invalid lifetime\n"); 2304 usage(); 2305 } 2306 break; 2307 case 'x': 2308 xcount = 0; 2309 break; 2310 default: 2311 usage(); 2312 } 2313 } 2314 ac -= optind; 2315 av += optind; 2316 2317 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) 2318 usage(); 2319 2320 if (allowed_providers == NULL) 2321 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); 2322 2323 if (ac == 0 && !c_flag && !s_flag) { 2324 shell = getenv("SHELL"); 2325 if (shell != NULL && (len = strlen(shell)) > 2 && 2326 strncmp(shell + len - 3, "csh", 3) == 0) 2327 c_flag = 1; 2328 } 2329 if (k_flag) { 2330 const char *errstr = NULL; 2331 2332 pidstr = getenv(SSH_AGENTPID_ENV_NAME); 2333 if (pidstr == NULL) { 2334 fprintf(stderr, "%s not set, cannot kill agent\n", 2335 SSH_AGENTPID_ENV_NAME); 2336 exit(1); 2337 } 2338 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); 2339 if (errstr) { 2340 fprintf(stderr, 2341 "%s=\"%s\", which is not a good PID: %s\n", 2342 SSH_AGENTPID_ENV_NAME, pidstr, errstr); 2343 exit(1); 2344 } 2345 if (kill(pid, SIGTERM) == -1) { 2346 perror("kill"); 2347 exit(1); 2348 } 2349 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; 2350 printf(format, SSH_AUTHSOCKET_ENV_NAME); 2351 printf(format, SSH_AGENTPID_ENV_NAME); 2352 printf("echo Agent pid %ld killed;\n", (long)pid); 2353 exit(0); 2354 } 2355 2356 /* 2357 * Minimum file descriptors: 2358 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + 2359 * a few spare for libc / stack protectors / sanitisers, etc. 2360 */ 2361 #define SSH_AGENT_MIN_FDS (3+1+1+1+4) 2362 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) 2363 fatal("%s: file descriptor rlimit %lld too low (minimum %u)", 2364 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); 2365 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; 2366 2367 parent_pid = getpid(); 2368 2369 if (agentsocket == NULL) { 2370 /* Create private directory for agent socket */ 2371 mktemp_proto(socket_dir, sizeof(socket_dir)); 2372 if (mkdtemp(socket_dir) == NULL) { 2373 perror("mkdtemp: private socket dir"); 2374 exit(1); 2375 } 2376 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, 2377 (long)parent_pid); 2378 } else { 2379 /* Try to use specified agent socket */ 2380 socket_dir[0] = '\0'; 2381 strlcpy(socket_name, agentsocket, sizeof socket_name); 2382 } 2383 2384 /* 2385 * Create socket early so it will exist before command gets run from 2386 * the parent. 2387 */ 2388 prev_mask = umask(0177); 2389 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); 2390 if (sock < 0) { 2391 /* XXX - unix_listener() calls error() not perror() */ 2392 *socket_name = '\0'; /* Don't unlink any existing file */ 2393 cleanup_exit(1); 2394 } 2395 umask(prev_mask); 2396 2397 /* 2398 * Fork, and have the parent execute the command, if any, or present 2399 * the socket data. The child continues as the authentication agent. 2400 */ 2401 if (D_flag || d_flag) { 2402 log_init(__progname, 2403 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 2404 SYSLOG_FACILITY_AUTH, 1); 2405 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2406 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2407 SSH_AUTHSOCKET_ENV_NAME); 2408 printf("echo Agent pid %ld;\n", (long)parent_pid); 2409 fflush(stdout); 2410 goto skip; 2411 } 2412 pid = fork(); 2413 if (pid == -1) { 2414 perror("fork"); 2415 cleanup_exit(1); 2416 } 2417 if (pid != 0) { /* Parent - execute the given command. */ 2418 close(sock); 2419 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); 2420 if (ac == 0) { 2421 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; 2422 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, 2423 SSH_AUTHSOCKET_ENV_NAME); 2424 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, 2425 SSH_AGENTPID_ENV_NAME); 2426 printf("echo Agent pid %ld;\n", (long)pid); 2427 exit(0); 2428 } 2429 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || 2430 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { 2431 perror("setenv"); 2432 exit(1); 2433 } 2434 execvp(av[0], av); 2435 perror(av[0]); 2436 exit(1); 2437 } 2438 /* child */ 2439 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); 2440 2441 if (setsid() == -1) { 2442 error("setsid: %s", strerror(errno)); 2443 cleanup_exit(1); 2444 } 2445 2446 (void)chdir("/"); 2447 if (stdfd_devnull(1, 1, 1) == -1) 2448 error_f("stdfd_devnull failed"); 2449 2450 #ifdef HAVE_SETRLIMIT 2451 /* deny core dumps, since memory contains unencrypted private keys */ 2452 rlim.rlim_cur = rlim.rlim_max = 0; 2453 if (setrlimit(RLIMIT_CORE, &rlim) == -1) { 2454 error("setrlimit RLIMIT_CORE: %s", strerror(errno)); 2455 cleanup_exit(1); 2456 } 2457 #endif 2458 2459 skip: 2460 2461 cleanup_pid = getpid(); 2462 2463 #ifdef ENABLE_PKCS11 2464 pkcs11_init(0); 2465 #endif 2466 new_socket(AUTH_SOCKET, sock); 2467 if (ac > 0) 2468 parent_alive_interval = 10; 2469 idtab_init(); 2470 ssh_signal(SIGPIPE, SIG_IGN); 2471 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); 2472 ssh_signal(SIGHUP, cleanup_handler); 2473 ssh_signal(SIGTERM, cleanup_handler); 2474 2475 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) 2476 fatal("%s: pledge: %s", __progname, strerror(errno)); 2477 platform_pledge_agent(); 2478 2479 while (1) { 2480 prepare_poll(&pfd, &npfd, &timeout, maxfds); 2481 result = poll(pfd, npfd, timeout); 2482 saved_errno = errno; 2483 if (parent_alive_interval != 0) 2484 check_parent_exists(); 2485 (void) reaper(); /* remove expired keys */ 2486 if (result == -1) { 2487 if (saved_errno == EINTR) 2488 continue; 2489 fatal("poll: %s", strerror(saved_errno)); 2490 } else if (result > 0) 2491 after_poll(pfd, npfd, maxfds); 2492 } 2493 /* NOTREACHED */ 2494 } 2495