1 /* $NetBSD: krl.c,v 1.2 2013/03/29 16:19:45 christos Exp $ */ 2 /* 3 * Copyright (c) 2012 Damien Miller <djm@mindrot.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* $OpenBSD: krl.c,v 1.9 2013/01/27 10:06:12 djm Exp $ */ 19 #include <sys/cdefs.h> 20 __RCSID("$NetBSD: krl.c,v 1.2 2013/03/29 16:19:45 christos Exp $"); 21 22 #include "includes.h" 23 #include <sys/types.h> 24 #include <sys/param.h> 25 #include <sys/tree.h> 26 #include <sys/queue.h> 27 28 #include <errno.h> 29 #include <fcntl.h> 30 #include <limits.h> 31 #include <string.h> 32 #include <time.h> 33 #include <unistd.h> 34 35 #include "buffer.h" 36 #include "key.h" 37 #include "authfile.h" 38 #include "err.h" 39 #include "misc.h" 40 #include "log.h" 41 #include "xmalloc.h" 42 43 #include "krl.h" 44 45 /* #define DEBUG_KRL */ 46 #ifdef DEBUG_KRL 47 # define KRL_DBG(x) debug3 x 48 #else 49 # define KRL_DBG(x) 50 #endif 51 52 /* 53 * Trees of revoked serial numbers, key IDs and keys. This allows 54 * quick searching, querying and producing lists in canonical order. 55 */ 56 57 /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */ 58 struct revoked_serial { 59 u_int64_t lo, hi; 60 RB_ENTRY(revoked_serial) tree_entry; 61 }; 62 static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b); 63 RB_HEAD(revoked_serial_tree, revoked_serial); 64 RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp); 65 66 /* Tree of key IDs */ 67 struct revoked_key_id { 68 char *key_id; 69 RB_ENTRY(revoked_key_id) tree_entry; 70 }; 71 static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b); 72 RB_HEAD(revoked_key_id_tree, revoked_key_id); 73 RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp); 74 75 /* Tree of blobs (used for keys and fingerprints) */ 76 struct revoked_blob { 77 u_char *blob; 78 u_int len; 79 RB_ENTRY(revoked_blob) tree_entry; 80 }; 81 static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b); 82 RB_HEAD(revoked_blob_tree, revoked_blob); 83 RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp); 84 85 /* Tracks revoked certs for a single CA */ 86 struct revoked_certs { 87 Key *ca_key; 88 struct revoked_serial_tree revoked_serials; 89 struct revoked_key_id_tree revoked_key_ids; 90 TAILQ_ENTRY(revoked_certs) entry; 91 }; 92 TAILQ_HEAD(revoked_certs_list, revoked_certs); 93 94 struct ssh_krl { 95 u_int64_t krl_version; 96 u_int64_t generated_date; 97 u_int64_t flags; 98 char *comment; 99 struct revoked_blob_tree revoked_keys; 100 struct revoked_blob_tree revoked_sha1s; 101 struct revoked_certs_list revoked_certs; 102 }; 103 104 /* Return equal if a and b overlap */ 105 static int 106 serial_cmp(struct revoked_serial *a, struct revoked_serial *b) 107 { 108 if (a->hi >= b->lo && a->lo <= b->hi) 109 return 0; 110 return a->lo < b->lo ? -1 : 1; 111 } 112 113 static int 114 key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b) 115 { 116 return strcmp(a->key_id, b->key_id); 117 } 118 119 static int 120 blob_cmp(struct revoked_blob *a, struct revoked_blob *b) 121 { 122 int r; 123 124 if (a->len != b->len) { 125 if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0) 126 return r; 127 return a->len > b->len ? 1 : -1; 128 } else 129 return memcmp(a->blob, b->blob, a->len); 130 } 131 132 struct ssh_krl * 133 ssh_krl_init(void) 134 { 135 struct ssh_krl *krl; 136 137 if ((krl = calloc(1, sizeof(*krl))) == NULL) 138 return NULL; 139 RB_INIT(&krl->revoked_keys); 140 RB_INIT(&krl->revoked_sha1s); 141 TAILQ_INIT(&krl->revoked_certs); 142 return krl; 143 } 144 145 static void 146 revoked_certs_free(struct revoked_certs *rc) 147 { 148 struct revoked_serial *rs, *trs; 149 struct revoked_key_id *rki, *trki; 150 151 RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) { 152 RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs); 153 free(rs); 154 } 155 RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) { 156 RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki); 157 free(rki->key_id); 158 free(rki); 159 } 160 if (rc->ca_key != NULL) 161 key_free(rc->ca_key); 162 } 163 164 void 165 ssh_krl_free(struct ssh_krl *krl) 166 { 167 struct revoked_blob *rb, *trb; 168 struct revoked_certs *rc, *trc; 169 170 if (krl == NULL) 171 return; 172 173 free(krl->comment); 174 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) { 175 RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb); 176 free(rb->blob); 177 free(rb); 178 } 179 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) { 180 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb); 181 free(rb->blob); 182 free(rb); 183 } 184 TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) { 185 TAILQ_REMOVE(&krl->revoked_certs, rc, entry); 186 revoked_certs_free(rc); 187 } 188 } 189 190 void 191 ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version) 192 { 193 krl->krl_version = version; 194 } 195 196 void 197 ssh_krl_set_comment(struct ssh_krl *krl, const char *comment) 198 { 199 free(krl->comment); 200 if ((krl->comment = strdup(comment)) == NULL) 201 fatal("%s: strdup", __func__); 202 } 203 204 /* 205 * Find the revoked_certs struct for a CA key. If allow_create is set then 206 * create a new one in the tree if one did not exist already. 207 */ 208 static int 209 revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key, 210 struct revoked_certs **rcp, int allow_create) 211 { 212 struct revoked_certs *rc; 213 214 *rcp = NULL; 215 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 216 if (key_equal(rc->ca_key, ca_key)) { 217 *rcp = rc; 218 return 0; 219 } 220 } 221 if (!allow_create) 222 return 0; 223 /* If this CA doesn't exist in the list then add it now */ 224 if ((rc = calloc(1, sizeof(*rc))) == NULL) 225 return -1; 226 if ((rc->ca_key = key_from_private(ca_key)) == NULL) { 227 free(rc); 228 return -1; 229 } 230 RB_INIT(&rc->revoked_serials); 231 RB_INIT(&rc->revoked_key_ids); 232 TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry); 233 debug3("%s: new CA %s", __func__, key_type(ca_key)); 234 *rcp = rc; 235 return 0; 236 } 237 238 static int 239 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi) 240 { 241 struct revoked_serial rs, *ers, *crs, *irs; 242 243 KRL_DBG(("%s: insert %"PRIu64":%"PRIu64, __func__, lo, hi)); 244 bzero(&rs, sizeof(rs)); 245 rs.lo = lo; 246 rs.hi = hi; 247 ers = RB_NFIND(revoked_serial_tree, rt, &rs); 248 if (ers == NULL || serial_cmp(ers, &rs) != 0) { 249 /* No entry matches. Just insert */ 250 if ((irs = malloc(sizeof(rs))) == NULL) 251 return -1; 252 memcpy(irs, &rs, sizeof(*irs)); 253 ers = RB_INSERT(revoked_serial_tree, rt, irs); 254 if (ers != NULL) { 255 KRL_DBG(("%s: bad: ers != NULL", __func__)); 256 /* Shouldn't happen */ 257 free(irs); 258 return -1; 259 } 260 ers = irs; 261 } else { 262 KRL_DBG(("%s: overlap found %"PRIu64":%"PRIu64, __func__, 263 ers->lo, ers->hi)); 264 /* 265 * The inserted entry overlaps an existing one. Grow the 266 * existing entry. 267 */ 268 if (ers->lo > lo) 269 ers->lo = lo; 270 if (ers->hi < hi) 271 ers->hi = hi; 272 } 273 /* 274 * The inserted or revised range might overlap or abut adjacent ones; 275 * coalesce as necessary. 276 */ 277 278 /* Check predecessors */ 279 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) { 280 KRL_DBG(("%s: pred %"PRIu64":%"PRIu64, __func__, 281 crs->lo, crs->hi)); 282 if (ers->lo != 0 && crs->hi < ers->lo - 1) 283 break; 284 /* This entry overlaps. */ 285 if (crs->lo < ers->lo) { 286 ers->lo = crs->lo; 287 KRL_DBG(("%s: pred extend %"PRIu64":%"PRIu64, __func__, 288 ers->lo, ers->hi)); 289 } 290 RB_REMOVE(revoked_serial_tree, rt, crs); 291 free(crs); 292 } 293 /* Check successors */ 294 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) { 295 KRL_DBG(("%s: succ %"PRIu64":%"PRIu64, __func__, crs->lo, 296 crs->hi)); 297 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1) 298 break; 299 /* This entry overlaps. */ 300 if (crs->hi > ers->hi) { 301 ers->hi = crs->hi; 302 KRL_DBG(("%s: succ extend %"PRIu64":%"PRIu64, __func__, 303 ers->lo, ers->hi)); 304 } 305 RB_REMOVE(revoked_serial_tree, rt, crs); 306 free(crs); 307 } 308 KRL_DBG(("%s: done, final %"PRIu64":%"PRIu64, __func__, ers->lo, 309 ers->hi)); 310 return 0; 311 } 312 313 int 314 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key, 315 u_int64_t serial) 316 { 317 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial); 318 } 319 320 int 321 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key, 322 u_int64_t lo, u_int64_t hi) 323 { 324 struct revoked_certs *rc; 325 326 if (lo > hi || lo == 0) 327 return -1; 328 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 329 return -1; 330 return insert_serial_range(&rc->revoked_serials, lo, hi); 331 } 332 333 int 334 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key, 335 const char *key_id) 336 { 337 struct revoked_key_id *rki, *erki; 338 struct revoked_certs *rc; 339 340 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 341 return -1; 342 343 debug3("%s: revoke %s", __func__, key_id); 344 if ((rki = calloc(1, sizeof(*rki))) == NULL || 345 (rki->key_id = strdup(key_id)) == NULL) { 346 free(rki); 347 fatal("%s: strdup", __func__); 348 } 349 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki); 350 if (erki != NULL) { 351 free(rki->key_id); 352 free(rki); 353 } 354 return 0; 355 } 356 357 /* Convert "key" to a public key blob without any certificate information */ 358 static int 359 plain_key_blob(const Key *key, u_char **blob, u_int *blen) 360 { 361 Key *kcopy; 362 int r; 363 364 if ((kcopy = key_from_private(key)) == NULL) 365 return -1; 366 if (key_is_cert(kcopy)) { 367 if (key_drop_cert(kcopy) != 0) { 368 error("%s: key_drop_cert", __func__); 369 key_free(kcopy); 370 return -1; 371 } 372 } 373 r = key_to_blob(kcopy, blob, blen); 374 free(kcopy); 375 return r == 0 ? -1 : 0; 376 } 377 378 /* Revoke a key blob. Ownership of blob is transferred to the tree */ 379 static int 380 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len) 381 { 382 struct revoked_blob *rb, *erb; 383 384 if ((rb = calloc(1, sizeof(*rb))) == NULL) 385 return -1; 386 rb->blob = blob; 387 rb->len = len; 388 erb = RB_INSERT(revoked_blob_tree, rbt, rb); 389 if (erb != NULL) { 390 free(rb->blob); 391 free(rb); 392 } 393 return 0; 394 } 395 396 int 397 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key) 398 { 399 u_char *blob; 400 u_int len; 401 402 debug3("%s: revoke type %s", __func__, key_type(key)); 403 if (plain_key_blob(key, &blob, &len) != 0) 404 return -1; 405 return revoke_blob(&krl->revoked_keys, blob, len); 406 } 407 408 int 409 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key) 410 { 411 u_char *blob; 412 u_int len; 413 414 debug3("%s: revoke type %s by sha1", __func__, key_type(key)); 415 if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL) 416 return -1; 417 return revoke_blob(&krl->revoked_sha1s, blob, len); 418 } 419 420 int 421 ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key) 422 { 423 if (!key_is_cert(key)) 424 return ssh_krl_revoke_key_sha1(krl, key); 425 426 if (key_cert_is_legacy(key) || key->cert->serial == 0) { 427 return ssh_krl_revoke_cert_by_key_id(krl, 428 key->cert->signature_key, 429 key->cert->key_id); 430 } else { 431 return ssh_krl_revoke_cert_by_serial(krl, 432 key->cert->signature_key, 433 key->cert->serial); 434 } 435 } 436 437 /* 438 * Select a copact next section type to emit in a KRL based on the 439 * current section type, the run length of contiguous revoked serial 440 * numbers and the gaps from the last and to the next revoked serial. 441 * Applies a mostly-accurate bit cost model to select the section type 442 * that will minimise the size of the resultant KRL. 443 */ 444 static int 445 choose_next_state(int current_state, u_int64_t contig, int final, 446 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section) 447 { 448 int new_state; 449 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart; 450 451 /* 452 * Avoid unsigned overflows. 453 * The limits are high enough to avoid confusing the calculations. 454 */ 455 contig = MIN(contig, 1ULL<<31); 456 last_gap = MIN(last_gap, 1ULL<<31); 457 next_gap = MIN(next_gap, 1ULL<<31); 458 459 /* 460 * Calculate the cost to switch from the current state to candidates. 461 * NB. range sections only ever contain a single range, so their 462 * switching cost is independent of the current_state. 463 */ 464 cost_list = cost_bitmap = cost_bitmap_restart = 0; 465 cost_range = 8; 466 switch (current_state) { 467 case KRL_SECTION_CERT_SERIAL_LIST: 468 cost_bitmap_restart = cost_bitmap = 8 + 64; 469 break; 470 case KRL_SECTION_CERT_SERIAL_BITMAP: 471 cost_list = 8; 472 cost_bitmap_restart = 8 + 64; 473 break; 474 case KRL_SECTION_CERT_SERIAL_RANGE: 475 case 0: 476 cost_bitmap_restart = cost_bitmap = 8 + 64; 477 cost_list = 8; 478 } 479 480 /* Estimate base cost in bits of each section type */ 481 cost_list += 64 * contig + (final ? 0 : 8+64); 482 cost_range += (2 * 64) + (final ? 0 : 8+64); 483 cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64)); 484 cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64)); 485 486 /* Convert to byte costs for actual comparison */ 487 cost_list = (cost_list + 7) / 8; 488 cost_bitmap = (cost_bitmap + 7) / 8; 489 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8; 490 cost_range = (cost_range + 7) / 8; 491 492 /* Now pick the best choice */ 493 *force_new_section = 0; 494 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 495 cost = cost_bitmap; 496 if (cost_range < cost) { 497 new_state = KRL_SECTION_CERT_SERIAL_RANGE; 498 cost = cost_range; 499 } 500 if (cost_list < cost) { 501 new_state = KRL_SECTION_CERT_SERIAL_LIST; 502 cost = cost_list; 503 } 504 if (cost_bitmap_restart < cost) { 505 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 506 *force_new_section = 1; 507 cost = cost_bitmap_restart; 508 } 509 debug3("%s: contig %"PRIu64" last_gap %"PRIu64" next_gap %"PRIu64 510 " final %d, costs: list %"PRIu64" range %"PRIu64" bitmap %"PRIu64 511 " new bitmap %"PRIu64", selected 0x%02x%s", __func__, contig, 512 last_gap, next_gap, final, cost_list, cost_range, cost_bitmap, 513 cost_bitmap_restart, new_state, 514 *force_new_section ? " restart" : ""); 515 return new_state; 516 } 517 518 /* Generate a KRL_SECTION_CERTIFICATES KRL section */ 519 static int 520 revoked_certs_generate(struct revoked_certs *rc, Buffer *buf) 521 { 522 int final, force_new_sect, r = -1; 523 u_int64_t i, contig, gap, last = 0, bitmap_start = 0; 524 struct revoked_serial *rs, *nrs; 525 struct revoked_key_id *rki; 526 int next_state, state = 0; 527 Buffer sect; 528 u_char *kblob = NULL; 529 u_int klen; 530 BIGNUM *bitmap = NULL; 531 532 /* Prepare CA scope key blob if we have one supplied */ 533 if (key_to_blob(rc->ca_key, &kblob, &klen) == 0) 534 return -1; 535 536 buffer_init(§); 537 538 /* Store the header */ 539 buffer_put_string(buf, kblob, klen); 540 buffer_put_string(buf, NULL, 0); /* Reserved */ 541 542 free(kblob); 543 544 /* Store the revoked serials. */ 545 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials); 546 rs != NULL; 547 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) { 548 debug3("%s: serial %"PRIu64":%"PRIu64" state 0x%02x", __func__, 549 rs->lo, rs->hi, state); 550 551 /* Check contiguous length and gap to next section (if any) */ 552 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs); 553 final = nrs == NULL; 554 gap = nrs == NULL ? 0 : nrs->lo - rs->hi; 555 contig = 1 + (rs->hi - rs->lo); 556 557 /* Choose next state based on these */ 558 next_state = choose_next_state(state, contig, final, 559 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect); 560 561 /* 562 * If the current section is a range section or has a different 563 * type to the next section, then finish it off now. 564 */ 565 if (state != 0 && (force_new_sect || next_state != state || 566 state == KRL_SECTION_CERT_SERIAL_RANGE)) { 567 debug3("%s: finish state 0x%02x", __func__, state); 568 switch (state) { 569 case KRL_SECTION_CERT_SERIAL_LIST: 570 case KRL_SECTION_CERT_SERIAL_RANGE: 571 break; 572 case KRL_SECTION_CERT_SERIAL_BITMAP: 573 buffer_put_bignum2(§, bitmap); 574 BN_free(bitmap); 575 bitmap = NULL; 576 break; 577 } 578 buffer_put_char(buf, state); 579 buffer_put_string(buf, 580 buffer_ptr(§), buffer_len(§)); 581 } 582 583 /* If we are starting a new section then prepare it now */ 584 if (next_state != state || force_new_sect) { 585 debug3("%s: start state 0x%02x", __func__, next_state); 586 state = next_state; 587 buffer_clear(§); 588 switch (state) { 589 case KRL_SECTION_CERT_SERIAL_LIST: 590 case KRL_SECTION_CERT_SERIAL_RANGE: 591 break; 592 case KRL_SECTION_CERT_SERIAL_BITMAP: 593 if ((bitmap = BN_new()) == NULL) 594 goto out; 595 bitmap_start = rs->lo; 596 buffer_put_int64(§, bitmap_start); 597 break; 598 } 599 } 600 601 /* Perform section-specific processing */ 602 switch (state) { 603 case KRL_SECTION_CERT_SERIAL_LIST: 604 for (i = 0; i < contig; i++) 605 buffer_put_int64(§, rs->lo + i); 606 break; 607 case KRL_SECTION_CERT_SERIAL_RANGE: 608 buffer_put_int64(§, rs->lo); 609 buffer_put_int64(§, rs->hi); 610 break; 611 case KRL_SECTION_CERT_SERIAL_BITMAP: 612 if (rs->lo - bitmap_start > INT_MAX) { 613 error("%s: insane bitmap gap", __func__); 614 goto out; 615 } 616 for (i = 0; i < contig; i++) { 617 if (BN_set_bit(bitmap, 618 rs->lo + i - bitmap_start) != 1) 619 goto out; 620 } 621 break; 622 } 623 last = rs->hi; 624 } 625 /* Flush the remaining section, if any */ 626 if (state != 0) { 627 debug3("%s: serial final flush for state 0x%02x", 628 __func__, state); 629 switch (state) { 630 case KRL_SECTION_CERT_SERIAL_LIST: 631 case KRL_SECTION_CERT_SERIAL_RANGE: 632 break; 633 case KRL_SECTION_CERT_SERIAL_BITMAP: 634 buffer_put_bignum2(§, bitmap); 635 BN_free(bitmap); 636 bitmap = NULL; 637 break; 638 } 639 buffer_put_char(buf, state); 640 buffer_put_string(buf, 641 buffer_ptr(§), buffer_len(§)); 642 } 643 debug3("%s: serial done ", __func__); 644 645 /* Now output a section for any revocations by key ID */ 646 buffer_clear(§); 647 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { 648 debug3("%s: key ID %s", __func__, rki->key_id); 649 buffer_put_cstring(§, rki->key_id); 650 } 651 if (buffer_len(§) != 0) { 652 buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID); 653 buffer_put_string(buf, buffer_ptr(§), 654 buffer_len(§)); 655 } 656 r = 0; 657 out: 658 if (bitmap != NULL) 659 BN_free(bitmap); 660 buffer_free(§); 661 return r; 662 } 663 664 int 665 ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys, 666 u_int nsign_keys) 667 { 668 int r = -1; 669 struct revoked_certs *rc; 670 struct revoked_blob *rb; 671 Buffer sect; 672 u_char *kblob = NULL, *sblob = NULL; 673 u_int klen, slen, i; 674 675 if (krl->generated_date == 0) 676 krl->generated_date = time(NULL); 677 678 buffer_init(§); 679 680 /* Store the header */ 681 buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1); 682 buffer_put_int(buf, KRL_FORMAT_VERSION); 683 buffer_put_int64(buf, krl->krl_version); 684 buffer_put_int64(buf, krl->generated_date); 685 buffer_put_int64(buf, krl->flags); 686 buffer_put_string(buf, NULL, 0); 687 buffer_put_cstring(buf, krl->comment ? krl->comment : ""); 688 689 /* Store sections for revoked certificates */ 690 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 691 if (revoked_certs_generate(rc, §) != 0) 692 goto out; 693 buffer_put_char(buf, KRL_SECTION_CERTIFICATES); 694 buffer_put_string(buf, buffer_ptr(§), 695 buffer_len(§)); 696 } 697 698 /* Finally, output sections for revocations by public key/hash */ 699 buffer_clear(§); 700 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { 701 debug3("%s: key len %u ", __func__, rb->len); 702 buffer_put_string(§, rb->blob, rb->len); 703 } 704 if (buffer_len(§) != 0) { 705 buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY); 706 buffer_put_string(buf, buffer_ptr(§), 707 buffer_len(§)); 708 } 709 buffer_clear(§); 710 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { 711 debug3("%s: hash len %u ", __func__, rb->len); 712 buffer_put_string(§, rb->blob, rb->len); 713 } 714 if (buffer_len(§) != 0) { 715 buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1); 716 buffer_put_string(buf, buffer_ptr(§), 717 buffer_len(§)); 718 } 719 720 for (i = 0; i < nsign_keys; i++) { 721 if (key_to_blob(sign_keys[i], &kblob, &klen) == 0) 722 goto out; 723 724 debug3("%s: signature key len %u", __func__, klen); 725 buffer_put_char(buf, KRL_SECTION_SIGNATURE); 726 buffer_put_string(buf, kblob, klen); 727 728 if (key_sign(sign_keys[i], &sblob, &slen, 729 buffer_ptr(buf), buffer_len(buf)) == -1) 730 goto out; 731 debug3("%s: signature sig len %u", __func__, slen); 732 buffer_put_string(buf, sblob, slen); 733 } 734 735 r = 0; 736 out: 737 free(kblob); 738 free(sblob); 739 buffer_free(§); 740 return r; 741 } 742 743 static void 744 format_timestamp(u_int64_t timestamp, char *ts, size_t nts) 745 { 746 time_t t; 747 struct tm *tm; 748 749 t = timestamp; 750 tm = localtime(&t); 751 *ts = '\0'; 752 strftime(ts, nts, "%Y%m%dT%H%M%S", tm); 753 } 754 755 static int 756 parse_revoked_certs(Buffer *buf, struct ssh_krl *krl) 757 { 758 int ret = -1, nbits; 759 char type; 760 u_char *blob; 761 u_int blen; 762 Buffer subsect; 763 u_int64_t serial, serial_lo, serial_hi; 764 BIGNUM *bitmap = NULL; 765 char *key_id = NULL; 766 Key *ca_key = NULL; 767 768 buffer_init(&subsect); 769 770 if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL || 771 buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */ 772 error("%s: buffer error", __func__); 773 goto out; 774 } 775 if ((ca_key = key_from_blob(blob, blen)) == NULL) 776 goto out; 777 778 while (buffer_len(buf) > 0) { 779 if (buffer_get_char_ret(&type, buf) != 0 || 780 (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) { 781 error("%s: buffer error", __func__); 782 goto out; 783 } 784 buffer_clear(&subsect); 785 buffer_append(&subsect, blob, blen); 786 debug3("%s: subsection type 0x%02x", __func__, type); 787 /* buffer_dump(&subsect); */ 788 789 switch (type) { 790 case KRL_SECTION_CERT_SERIAL_LIST: 791 while (buffer_len(&subsect) > 0) { 792 if (buffer_get_int64_ret(&serial, 793 &subsect) != 0) { 794 error("%s: buffer error", __func__); 795 goto out; 796 } 797 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 798 serial) != 0) { 799 error("%s: update failed", __func__); 800 goto out; 801 } 802 } 803 break; 804 case KRL_SECTION_CERT_SERIAL_RANGE: 805 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 806 buffer_get_int64_ret(&serial_hi, &subsect) != 0) { 807 error("%s: buffer error", __func__); 808 goto out; 809 } 810 if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key, 811 serial_lo, serial_hi) != 0) { 812 error("%s: update failed", __func__); 813 goto out; 814 } 815 break; 816 case KRL_SECTION_CERT_SERIAL_BITMAP: 817 if ((bitmap = BN_new()) == NULL) { 818 error("%s: BN_new", __func__); 819 goto out; 820 } 821 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 822 buffer_get_bignum2_ret(&subsect, bitmap) != 0) { 823 error("%s: buffer error", __func__); 824 goto out; 825 } 826 if ((nbits = BN_num_bits(bitmap)) < 0) { 827 error("%s: bitmap bits < 0", __func__); 828 goto out; 829 } 830 for (serial = 0; serial < (u_int)nbits; serial++) { 831 if (serial > 0 && serial_lo + serial == 0) { 832 error("%s: bitmap wraps u64", __func__); 833 goto out; 834 } 835 if (!BN_is_bit_set(bitmap, serial)) 836 continue; 837 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 838 serial_lo + serial) != 0) { 839 error("%s: update failed", __func__); 840 goto out; 841 } 842 } 843 BN_free(bitmap); 844 bitmap = NULL; 845 break; 846 case KRL_SECTION_CERT_KEY_ID: 847 while (buffer_len(&subsect) > 0) { 848 if ((key_id = buffer_get_cstring_ret(&subsect, 849 NULL)) == NULL) { 850 error("%s: buffer error", __func__); 851 goto out; 852 } 853 if (ssh_krl_revoke_cert_by_key_id(krl, ca_key, 854 key_id) != 0) { 855 error("%s: update failed", __func__); 856 goto out; 857 } 858 free(key_id); 859 key_id = NULL; 860 } 861 break; 862 default: 863 error("Unsupported KRL certificate section %u", type); 864 goto out; 865 } 866 if (buffer_len(&subsect) > 0) { 867 error("KRL certificate section contains unparsed data"); 868 goto out; 869 } 870 } 871 872 ret = 0; 873 out: 874 if (ca_key != NULL) 875 key_free(ca_key); 876 if (bitmap != NULL) 877 BN_free(bitmap); 878 free(key_id); 879 buffer_free(&subsect); 880 return ret; 881 } 882 883 884 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */ 885 int 886 ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp, 887 const Key **sign_ca_keys, u_int nsign_ca_keys) 888 { 889 Buffer copy, sect; 890 struct ssh_krl *krl; 891 char timestamp[64]; 892 int ret = -1, r, sig_seen; 893 Key *key = NULL, **ca_used = NULL; 894 char type; 895 u_char *blob; 896 u_int i, j, sig_off, sects_off, blen, format_version, nca_used = 0; 897 898 *krlp = NULL; 899 if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 || 900 memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) { 901 debug3("%s: not a KRL", __func__); 902 /* 903 * Return success but a NULL *krlp here to signal that the 904 * file might be a simple list of keys. 905 */ 906 return 0; 907 } 908 909 /* Take a copy of the KRL buffer so we can verify its signature later */ 910 buffer_init(©); 911 buffer_append(©, buffer_ptr(buf), buffer_len(buf)); 912 913 buffer_init(§); 914 buffer_consume(©, sizeof(KRL_MAGIC) - 1); 915 916 if ((krl = ssh_krl_init()) == NULL) { 917 error("%s: alloc failed", __func__); 918 goto out; 919 } 920 921 if (buffer_get_int_ret(&format_version, ©) != 0) { 922 error("%s: KRL truncated", __func__); 923 goto out; 924 } 925 if (format_version != KRL_FORMAT_VERSION) { 926 error("%s: KRL unsupported format version %u", 927 __func__, format_version); 928 goto out; 929 } 930 if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 || 931 buffer_get_int64_ret(&krl->generated_date, ©) != 0 || 932 buffer_get_int64_ret(&krl->flags, ©) != 0 || 933 buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */ 934 (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) { 935 error("%s: buffer error", __func__); 936 goto out; 937 } 938 939 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); 940 debug("KRL version %"PRIu64" generated at %s%s%s", 941 krl->krl_version, 942 timestamp, *krl->comment ? ": " : "", krl->comment); 943 944 /* 945 * 1st pass: verify signatures, if any. This is done to avoid 946 * detailed parsing of data whose provenance is unverified. 947 */ 948 sig_seen = 0; 949 sects_off = buffer_len(buf) - buffer_len(©); 950 while (buffer_len(©) > 0) { 951 if (buffer_get_char_ret(&type, ©) != 0 || 952 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 953 error("%s: buffer error", __func__); 954 goto out; 955 } 956 debug3("%s: first pass, section 0x%02x", __func__, type); 957 if (type != KRL_SECTION_SIGNATURE) { 958 if (sig_seen) { 959 error("KRL contains non-signature section " 960 "after signature"); 961 goto out; 962 } 963 /* Not interested for now. */ 964 continue; 965 } 966 sig_seen = 1; 967 /* First string component is the signing key */ 968 if ((key = key_from_blob(blob, blen)) == NULL) { 969 error("%s: invalid signature key", __func__); 970 goto out; 971 } 972 sig_off = buffer_len(buf) - buffer_len(©); 973 /* Second string component is the signature itself */ 974 if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 975 error("%s: buffer error", __func__); 976 goto out; 977 } 978 /* Check signature over entire KRL up to this point */ 979 if (key_verify(key, blob, blen, 980 buffer_ptr(buf), buffer_len(buf) - sig_off) == -1) { 981 error("bad signaure on KRL"); 982 goto out; 983 } 984 /* Check if this key has already signed this KRL */ 985 for (i = 0; i < nca_used; i++) { 986 if (key_equal(ca_used[i], key)) { 987 error("KRL signed more than once with " 988 "the same key"); 989 goto out; 990 } 991 } 992 /* Record keys used to sign the KRL */ 993 ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used)); 994 ca_used[nca_used++] = key; 995 key = NULL; 996 break; 997 } 998 999 /* 1000 * 2nd pass: parse and load the KRL, skipping the header to the point 1001 * where the section start. 1002 */ 1003 buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off, 1004 buffer_len(buf) - sects_off); 1005 while (buffer_len(©) > 0) { 1006 if (buffer_get_char_ret(&type, ©) != 0 || 1007 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 1008 error("%s: buffer error", __func__); 1009 goto out; 1010 } 1011 debug3("%s: second pass, section 0x%02x", __func__, type); 1012 buffer_clear(§); 1013 buffer_append(§, blob, blen); 1014 1015 switch (type) { 1016 case KRL_SECTION_CERTIFICATES: 1017 if ((r = parse_revoked_certs(§, krl)) != 0) 1018 goto out; 1019 break; 1020 case KRL_SECTION_EXPLICIT_KEY: 1021 case KRL_SECTION_FINGERPRINT_SHA1: 1022 while (buffer_len(§) > 0) { 1023 if ((blob = buffer_get_string_ret(§, 1024 &blen)) == NULL) { 1025 error("%s: buffer error", __func__); 1026 goto out; 1027 } 1028 if (type == KRL_SECTION_FINGERPRINT_SHA1 && 1029 blen != 20) { 1030 error("%s: bad SHA1 length", __func__); 1031 goto out; 1032 } 1033 if (revoke_blob( 1034 type == KRL_SECTION_EXPLICIT_KEY ? 1035 &krl->revoked_keys : &krl->revoked_sha1s, 1036 blob, blen) != 0) 1037 goto out; /* revoke_blob frees blob */ 1038 } 1039 break; 1040 case KRL_SECTION_SIGNATURE: 1041 /* Handled above, but still need to stay in synch */ 1042 buffer_clear(§); 1043 if ((blob = buffer_get_string_ptr_ret(©, 1044 &blen)) == NULL) { 1045 error("%s: buffer error", __func__); 1046 goto out; 1047 } 1048 break; 1049 default: 1050 error("Unsupported KRL section %u", type); 1051 goto out; 1052 } 1053 if (buffer_len(§) > 0) { 1054 error("KRL section contains unparsed data"); 1055 goto out; 1056 } 1057 } 1058 1059 /* Check that the key(s) used to sign the KRL weren't revoked */ 1060 sig_seen = 0; 1061 for (i = 0; i < nca_used; i++) { 1062 if (ssh_krl_check_key(krl, ca_used[i]) == 0) 1063 sig_seen = 1; 1064 else { 1065 key_free(ca_used[i]); 1066 ca_used[i] = NULL; 1067 } 1068 } 1069 if (nca_used && !sig_seen) { 1070 error("All keys used to sign KRL were revoked"); 1071 goto out; 1072 } 1073 1074 /* If we have CA keys, then verify that one was used to sign the KRL */ 1075 if (sig_seen && nsign_ca_keys != 0) { 1076 sig_seen = 0; 1077 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) { 1078 for (j = 0; j < nca_used; j++) { 1079 if (ca_used[j] == NULL) 1080 continue; 1081 if (key_equal(ca_used[j], sign_ca_keys[i])) { 1082 sig_seen = 1; 1083 break; 1084 } 1085 } 1086 } 1087 if (!sig_seen) { 1088 error("KRL not signed with any trusted key"); 1089 goto out; 1090 } 1091 } 1092 1093 *krlp = krl; 1094 ret = 0; 1095 out: 1096 if (ret != 0) 1097 ssh_krl_free(krl); 1098 for (i = 0; i < nca_used; i++) { 1099 if (ca_used[i] != NULL) 1100 key_free(ca_used[i]); 1101 } 1102 free(ca_used); 1103 if (key != NULL) 1104 key_free(key); 1105 buffer_free(©); 1106 buffer_free(§); 1107 return ret; 1108 } 1109 1110 /* Checks whether a given key/cert is revoked. Does not check its CA */ 1111 static int 1112 is_key_revoked(struct ssh_krl *krl, const Key *key) 1113 { 1114 struct revoked_blob rb, *erb; 1115 struct revoked_serial rs, *ers; 1116 struct revoked_key_id rki, *erki; 1117 struct revoked_certs *rc; 1118 1119 /* Check explicitly revoked hashes first */ 1120 bzero(&rb, sizeof(rb)); 1121 if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL) 1122 return -1; 1123 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb); 1124 free(rb.blob); 1125 if (erb != NULL) { 1126 debug("%s: revoked by key SHA1", __func__); 1127 return -1; 1128 } 1129 1130 /* Next, explicit keys */ 1131 bzero(&rb, sizeof(rb)); 1132 if (plain_key_blob(key, &rb.blob, &rb.len) != 0) 1133 return -1; 1134 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb); 1135 free(rb.blob); 1136 if (erb != NULL) { 1137 debug("%s: revoked by explicit key", __func__); 1138 return -1; 1139 } 1140 1141 if (!key_is_cert(key)) 1142 return 0; 1143 1144 /* Check cert revocation */ 1145 if (revoked_certs_for_ca_key(krl, key->cert->signature_key, 1146 &rc, 0) != 0) 1147 return -1; 1148 if (rc == NULL) 1149 return 0; /* No entry for this CA */ 1150 1151 /* Check revocation by cert key ID */ 1152 bzero(&rki, sizeof(rki)); 1153 rki.key_id = key->cert->key_id; 1154 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki); 1155 if (erki != NULL) { 1156 debug("%s: revoked by key ID", __func__); 1157 return -1; 1158 } 1159 1160 /* 1161 * Legacy cert formats lack serial numbers. Zero serials numbers 1162 * are ignored (it's the default when the CA doesn't specify one). 1163 */ 1164 if (key_cert_is_legacy(key) || key->cert->serial == 0) 1165 return 0; 1166 1167 bzero(&rs, sizeof(rs)); 1168 rs.lo = rs.hi = key->cert->serial; 1169 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs); 1170 if (ers != NULL) { 1171 KRL_DBG(("%s: %"PRIu64" matched %"PRIu64":%"PRiu64, __func__, 1172 key->cert->serial, ers->lo, ers->hi)); 1173 debug("%s: revoked by serial", __func__); 1174 return -1; 1175 } 1176 KRL_DBG(("%s: %"PRIu64" no match", __func__, key->cert->serial)); 1177 1178 return 0; 1179 } 1180 1181 int 1182 ssh_krl_check_key(struct ssh_krl *krl, const Key *key) 1183 { 1184 int r; 1185 1186 debug2("%s: checking key", __func__); 1187 if ((r = is_key_revoked(krl, key)) != 0) 1188 return r; 1189 if (key_is_cert(key)) { 1190 debug2("%s: checking CA key", __func__); 1191 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0) 1192 return r; 1193 } 1194 debug3("%s: key okay", __func__); 1195 return 0; 1196 } 1197 1198 /* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */ 1199 int 1200 ssh_krl_file_contains_key(const char *path, const Key *key) 1201 { 1202 Buffer krlbuf; 1203 struct ssh_krl *krl; 1204 int revoked, fd; 1205 1206 if (path == NULL) 1207 return 0; 1208 1209 if ((fd = open(path, O_RDONLY)) == -1) { 1210 error("open %s: %s", path, strerror(errno)); 1211 error("Revoked keys file not accessible - refusing public key " 1212 "authentication"); 1213 return -1; 1214 } 1215 buffer_init(&krlbuf); 1216 if (!key_load_file(fd, path, &krlbuf)) { 1217 close(fd); 1218 buffer_free(&krlbuf); 1219 error("Revoked keys file not readable - refusing public key " 1220 "authentication"); 1221 return -1; 1222 } 1223 close(fd); 1224 if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) { 1225 buffer_free(&krlbuf); 1226 error("Invalid KRL, refusing public key " 1227 "authentication"); 1228 return -1; 1229 } 1230 buffer_free(&krlbuf); 1231 if (krl == NULL) { 1232 debug3("%s: %s is not a KRL file", __func__, path); 1233 return -2; 1234 } 1235 debug2("%s: checking KRL %s", __func__, path); 1236 revoked = ssh_krl_check_key(krl, key) != 0; 1237 ssh_krl_free(krl); 1238 return revoked ? -1 : 0; 1239 } 1240