1 /* 2 * Copyright (c) 2012 Damien Miller <djm@mindrot.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 /* $OpenBSD: krl.c,v 1.17 2014/06/24 01:13:21 djm Exp $ */ 18 19 #include "includes.h" 20 21 #include <sys/types.h> 22 #include <sys/param.h> 23 #include <openbsd-compat/sys-tree.h> 24 #include <openbsd-compat/sys-queue.h> 25 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <limits.h> 29 #include <string.h> 30 #include <time.h> 31 #include <unistd.h> 32 33 #include "buffer.h" 34 #include "key.h" 35 #include "authfile.h" 36 #include "misc.h" 37 #include "log.h" 38 #include "xmalloc.h" 39 40 #include "krl.h" 41 42 /* #define DEBUG_KRL */ 43 #ifdef DEBUG_KRL 44 # define KRL_DBG(x) debug3 x 45 #else 46 # define KRL_DBG(x) 47 #endif 48 49 /* 50 * Trees of revoked serial numbers, key IDs and keys. This allows 51 * quick searching, querying and producing lists in canonical order. 52 */ 53 54 /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */ 55 struct revoked_serial { 56 u_int64_t lo, hi; 57 RB_ENTRY(revoked_serial) tree_entry; 58 }; 59 static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b); 60 RB_HEAD(revoked_serial_tree, revoked_serial); 61 RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp); 62 63 /* Tree of key IDs */ 64 struct revoked_key_id { 65 char *key_id; 66 RB_ENTRY(revoked_key_id) tree_entry; 67 }; 68 static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b); 69 RB_HEAD(revoked_key_id_tree, revoked_key_id); 70 RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp); 71 72 /* Tree of blobs (used for keys and fingerprints) */ 73 struct revoked_blob { 74 u_char *blob; 75 u_int len; 76 RB_ENTRY(revoked_blob) tree_entry; 77 }; 78 static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b); 79 RB_HEAD(revoked_blob_tree, revoked_blob); 80 RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp); 81 82 /* Tracks revoked certs for a single CA */ 83 struct revoked_certs { 84 Key *ca_key; 85 struct revoked_serial_tree revoked_serials; 86 struct revoked_key_id_tree revoked_key_ids; 87 TAILQ_ENTRY(revoked_certs) entry; 88 }; 89 TAILQ_HEAD(revoked_certs_list, revoked_certs); 90 91 struct ssh_krl { 92 u_int64_t krl_version; 93 u_int64_t generated_date; 94 u_int64_t flags; 95 char *comment; 96 struct revoked_blob_tree revoked_keys; 97 struct revoked_blob_tree revoked_sha1s; 98 struct revoked_certs_list revoked_certs; 99 }; 100 101 /* Return equal if a and b overlap */ 102 static int 103 serial_cmp(struct revoked_serial *a, struct revoked_serial *b) 104 { 105 if (a->hi >= b->lo && a->lo <= b->hi) 106 return 0; 107 return a->lo < b->lo ? -1 : 1; 108 } 109 110 static int 111 key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b) 112 { 113 return strcmp(a->key_id, b->key_id); 114 } 115 116 static int 117 blob_cmp(struct revoked_blob *a, struct revoked_blob *b) 118 { 119 int r; 120 121 if (a->len != b->len) { 122 if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0) 123 return r; 124 return a->len > b->len ? 1 : -1; 125 } else 126 return memcmp(a->blob, b->blob, a->len); 127 } 128 129 struct ssh_krl * 130 ssh_krl_init(void) 131 { 132 struct ssh_krl *krl; 133 134 if ((krl = calloc(1, sizeof(*krl))) == NULL) 135 return NULL; 136 RB_INIT(&krl->revoked_keys); 137 RB_INIT(&krl->revoked_sha1s); 138 TAILQ_INIT(&krl->revoked_certs); 139 return krl; 140 } 141 142 static void 143 revoked_certs_free(struct revoked_certs *rc) 144 { 145 struct revoked_serial *rs, *trs; 146 struct revoked_key_id *rki, *trki; 147 148 RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) { 149 RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs); 150 free(rs); 151 } 152 RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) { 153 RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki); 154 free(rki->key_id); 155 free(rki); 156 } 157 if (rc->ca_key != NULL) 158 key_free(rc->ca_key); 159 } 160 161 void 162 ssh_krl_free(struct ssh_krl *krl) 163 { 164 struct revoked_blob *rb, *trb; 165 struct revoked_certs *rc, *trc; 166 167 if (krl == NULL) 168 return; 169 170 free(krl->comment); 171 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) { 172 RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb); 173 free(rb->blob); 174 free(rb); 175 } 176 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) { 177 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb); 178 free(rb->blob); 179 free(rb); 180 } 181 TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) { 182 TAILQ_REMOVE(&krl->revoked_certs, rc, entry); 183 revoked_certs_free(rc); 184 } 185 } 186 187 void 188 ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version) 189 { 190 krl->krl_version = version; 191 } 192 193 void 194 ssh_krl_set_comment(struct ssh_krl *krl, const char *comment) 195 { 196 free(krl->comment); 197 if ((krl->comment = strdup(comment)) == NULL) 198 fatal("%s: strdup", __func__); 199 } 200 201 /* 202 * Find the revoked_certs struct for a CA key. If allow_create is set then 203 * create a new one in the tree if one did not exist already. 204 */ 205 static int 206 revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key, 207 struct revoked_certs **rcp, int allow_create) 208 { 209 struct revoked_certs *rc; 210 211 *rcp = NULL; 212 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 213 if (key_equal(rc->ca_key, ca_key)) { 214 *rcp = rc; 215 return 0; 216 } 217 } 218 if (!allow_create) 219 return 0; 220 /* If this CA doesn't exist in the list then add it now */ 221 if ((rc = calloc(1, sizeof(*rc))) == NULL) 222 return -1; 223 if ((rc->ca_key = key_from_private(ca_key)) == NULL) { 224 free(rc); 225 return -1; 226 } 227 RB_INIT(&rc->revoked_serials); 228 RB_INIT(&rc->revoked_key_ids); 229 TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry); 230 debug3("%s: new CA %s", __func__, key_type(ca_key)); 231 *rcp = rc; 232 return 0; 233 } 234 235 static int 236 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi) 237 { 238 struct revoked_serial rs, *ers, *crs, *irs; 239 240 KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi)); 241 memset(&rs, 0, sizeof(rs)); 242 rs.lo = lo; 243 rs.hi = hi; 244 ers = RB_NFIND(revoked_serial_tree, rt, &rs); 245 if (ers == NULL || serial_cmp(ers, &rs) != 0) { 246 /* No entry matches. Just insert */ 247 if ((irs = malloc(sizeof(rs))) == NULL) 248 return -1; 249 memcpy(irs, &rs, sizeof(*irs)); 250 ers = RB_INSERT(revoked_serial_tree, rt, irs); 251 if (ers != NULL) { 252 KRL_DBG(("%s: bad: ers != NULL", __func__)); 253 /* Shouldn't happen */ 254 free(irs); 255 return -1; 256 } 257 ers = irs; 258 } else { 259 KRL_DBG(("%s: overlap found %llu:%llu", __func__, 260 ers->lo, ers->hi)); 261 /* 262 * The inserted entry overlaps an existing one. Grow the 263 * existing entry. 264 */ 265 if (ers->lo > lo) 266 ers->lo = lo; 267 if (ers->hi < hi) 268 ers->hi = hi; 269 } 270 /* 271 * The inserted or revised range might overlap or abut adjacent ones; 272 * coalesce as necessary. 273 */ 274 275 /* Check predecessors */ 276 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) { 277 KRL_DBG(("%s: pred %llu:%llu", __func__, crs->lo, crs->hi)); 278 if (ers->lo != 0 && crs->hi < ers->lo - 1) 279 break; 280 /* This entry overlaps. */ 281 if (crs->lo < ers->lo) { 282 ers->lo = crs->lo; 283 KRL_DBG(("%s: pred extend %llu:%llu", __func__, 284 ers->lo, ers->hi)); 285 } 286 RB_REMOVE(revoked_serial_tree, rt, crs); 287 free(crs); 288 } 289 /* Check successors */ 290 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) { 291 KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi)); 292 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1) 293 break; 294 /* This entry overlaps. */ 295 if (crs->hi > ers->hi) { 296 ers->hi = crs->hi; 297 KRL_DBG(("%s: succ extend %llu:%llu", __func__, 298 ers->lo, ers->hi)); 299 } 300 RB_REMOVE(revoked_serial_tree, rt, crs); 301 free(crs); 302 } 303 KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi)); 304 return 0; 305 } 306 307 int 308 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key, 309 u_int64_t serial) 310 { 311 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial); 312 } 313 314 int 315 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key, 316 u_int64_t lo, u_int64_t hi) 317 { 318 struct revoked_certs *rc; 319 320 if (lo > hi || lo == 0) 321 return -1; 322 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 323 return -1; 324 return insert_serial_range(&rc->revoked_serials, lo, hi); 325 } 326 327 int 328 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key, 329 const char *key_id) 330 { 331 struct revoked_key_id *rki, *erki; 332 struct revoked_certs *rc; 333 334 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 335 return -1; 336 337 debug3("%s: revoke %s", __func__, key_id); 338 if ((rki = calloc(1, sizeof(*rki))) == NULL || 339 (rki->key_id = strdup(key_id)) == NULL) { 340 free(rki); 341 fatal("%s: strdup", __func__); 342 } 343 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki); 344 if (erki != NULL) { 345 free(rki->key_id); 346 free(rki); 347 } 348 return 0; 349 } 350 351 /* Convert "key" to a public key blob without any certificate information */ 352 static int 353 plain_key_blob(const Key *key, u_char **blob, u_int *blen) 354 { 355 Key *kcopy; 356 int r; 357 358 if ((kcopy = key_from_private(key)) == NULL) 359 return -1; 360 if (key_is_cert(kcopy)) { 361 if (key_drop_cert(kcopy) != 0) { 362 error("%s: key_drop_cert", __func__); 363 key_free(kcopy); 364 return -1; 365 } 366 } 367 r = key_to_blob(kcopy, blob, blen); 368 free(kcopy); 369 return r; 370 } 371 372 /* Revoke a key blob. Ownership of blob is transferred to the tree */ 373 static int 374 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len) 375 { 376 struct revoked_blob *rb, *erb; 377 378 if ((rb = calloc(1, sizeof(*rb))) == NULL) 379 return -1; 380 rb->blob = blob; 381 rb->len = len; 382 erb = RB_INSERT(revoked_blob_tree, rbt, rb); 383 if (erb != NULL) { 384 free(rb->blob); 385 free(rb); 386 } 387 return 0; 388 } 389 390 int 391 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key) 392 { 393 u_char *blob; 394 u_int len; 395 396 debug3("%s: revoke type %s", __func__, key_type(key)); 397 if (plain_key_blob(key, &blob, &len) < 0) 398 return -1; 399 return revoke_blob(&krl->revoked_keys, blob, len); 400 } 401 402 int 403 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key) 404 { 405 u_char *blob; 406 u_int len; 407 408 debug3("%s: revoke type %s by sha1", __func__, key_type(key)); 409 if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL) 410 return -1; 411 return revoke_blob(&krl->revoked_sha1s, blob, len); 412 } 413 414 int 415 ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key) 416 { 417 if (!key_is_cert(key)) 418 return ssh_krl_revoke_key_sha1(krl, key); 419 420 if (key_cert_is_legacy(key) || key->cert->serial == 0) { 421 return ssh_krl_revoke_cert_by_key_id(krl, 422 key->cert->signature_key, 423 key->cert->key_id); 424 } else { 425 return ssh_krl_revoke_cert_by_serial(krl, 426 key->cert->signature_key, 427 key->cert->serial); 428 } 429 } 430 431 /* 432 * Select a copact next section type to emit in a KRL based on the 433 * current section type, the run length of contiguous revoked serial 434 * numbers and the gaps from the last and to the next revoked serial. 435 * Applies a mostly-accurate bit cost model to select the section type 436 * that will minimise the size of the resultant KRL. 437 */ 438 static int 439 choose_next_state(int current_state, u_int64_t contig, int final, 440 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section) 441 { 442 int new_state; 443 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart; 444 445 /* 446 * Avoid unsigned overflows. 447 * The limits are high enough to avoid confusing the calculations. 448 */ 449 contig = MIN(contig, 1ULL<<31); 450 last_gap = MIN(last_gap, 1ULL<<31); 451 next_gap = MIN(next_gap, 1ULL<<31); 452 453 /* 454 * Calculate the cost to switch from the current state to candidates. 455 * NB. range sections only ever contain a single range, so their 456 * switching cost is independent of the current_state. 457 */ 458 cost_list = cost_bitmap = cost_bitmap_restart = 0; 459 cost_range = 8; 460 switch (current_state) { 461 case KRL_SECTION_CERT_SERIAL_LIST: 462 cost_bitmap_restart = cost_bitmap = 8 + 64; 463 break; 464 case KRL_SECTION_CERT_SERIAL_BITMAP: 465 cost_list = 8; 466 cost_bitmap_restart = 8 + 64; 467 break; 468 case KRL_SECTION_CERT_SERIAL_RANGE: 469 case 0: 470 cost_bitmap_restart = cost_bitmap = 8 + 64; 471 cost_list = 8; 472 } 473 474 /* Estimate base cost in bits of each section type */ 475 cost_list += 64 * contig + (final ? 0 : 8+64); 476 cost_range += (2 * 64) + (final ? 0 : 8+64); 477 cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64)); 478 cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64)); 479 480 /* Convert to byte costs for actual comparison */ 481 cost_list = (cost_list + 7) / 8; 482 cost_bitmap = (cost_bitmap + 7) / 8; 483 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8; 484 cost_range = (cost_range + 7) / 8; 485 486 /* Now pick the best choice */ 487 *force_new_section = 0; 488 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 489 cost = cost_bitmap; 490 if (cost_range < cost) { 491 new_state = KRL_SECTION_CERT_SERIAL_RANGE; 492 cost = cost_range; 493 } 494 if (cost_list < cost) { 495 new_state = KRL_SECTION_CERT_SERIAL_LIST; 496 cost = cost_list; 497 } 498 if (cost_bitmap_restart < cost) { 499 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 500 *force_new_section = 1; 501 cost = cost_bitmap_restart; 502 } 503 debug3("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:" 504 "list %llu range %llu bitmap %llu new bitmap %llu, " 505 "selected 0x%02x%s", __func__, (long long unsigned)contig, 506 (long long unsigned)last_gap, (long long unsigned)next_gap, final, 507 (long long unsigned)cost_list, (long long unsigned)cost_range, 508 (long long unsigned)cost_bitmap, 509 (long long unsigned)cost_bitmap_restart, new_state, 510 *force_new_section ? " restart" : ""); 511 return new_state; 512 } 513 514 /* Generate a KRL_SECTION_CERTIFICATES KRL section */ 515 static int 516 revoked_certs_generate(struct revoked_certs *rc, Buffer *buf) 517 { 518 int final, force_new_sect, r = -1; 519 u_int64_t i, contig, gap, last = 0, bitmap_start = 0; 520 struct revoked_serial *rs, *nrs; 521 struct revoked_key_id *rki; 522 int next_state, state = 0; 523 Buffer sect; 524 u_char *kblob = NULL; 525 u_int klen; 526 BIGNUM *bitmap = NULL; 527 528 /* Prepare CA scope key blob if we have one supplied */ 529 if (key_to_blob(rc->ca_key, &kblob, &klen) == 0) 530 return -1; 531 532 buffer_init(§); 533 534 /* Store the header */ 535 buffer_put_string(buf, kblob, klen); 536 buffer_put_string(buf, NULL, 0); /* Reserved */ 537 538 free(kblob); 539 540 /* Store the revoked serials. */ 541 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials); 542 rs != NULL; 543 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) { 544 debug3("%s: serial %llu:%llu state 0x%02x", __func__, 545 (long long unsigned)rs->lo, (long long unsigned)rs->hi, 546 state); 547 548 /* Check contiguous length and gap to next section (if any) */ 549 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs); 550 final = nrs == NULL; 551 gap = nrs == NULL ? 0 : nrs->lo - rs->hi; 552 contig = 1 + (rs->hi - rs->lo); 553 554 /* Choose next state based on these */ 555 next_state = choose_next_state(state, contig, final, 556 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect); 557 558 /* 559 * If the current section is a range section or has a different 560 * type to the next section, then finish it off now. 561 */ 562 if (state != 0 && (force_new_sect || next_state != state || 563 state == KRL_SECTION_CERT_SERIAL_RANGE)) { 564 debug3("%s: finish state 0x%02x", __func__, state); 565 switch (state) { 566 case KRL_SECTION_CERT_SERIAL_LIST: 567 case KRL_SECTION_CERT_SERIAL_RANGE: 568 break; 569 case KRL_SECTION_CERT_SERIAL_BITMAP: 570 buffer_put_bignum2(§, bitmap); 571 BN_free(bitmap); 572 bitmap = NULL; 573 break; 574 } 575 buffer_put_char(buf, state); 576 buffer_put_string(buf, 577 buffer_ptr(§), buffer_len(§)); 578 buffer_clear(§); 579 } 580 581 /* If we are starting a new section then prepare it now */ 582 if (next_state != state || force_new_sect) { 583 debug3("%s: start state 0x%02x", __func__, next_state); 584 state = next_state; 585 buffer_clear(§); 586 switch (state) { 587 case KRL_SECTION_CERT_SERIAL_LIST: 588 case KRL_SECTION_CERT_SERIAL_RANGE: 589 break; 590 case KRL_SECTION_CERT_SERIAL_BITMAP: 591 if ((bitmap = BN_new()) == NULL) 592 goto out; 593 bitmap_start = rs->lo; 594 buffer_put_int64(§, bitmap_start); 595 break; 596 } 597 } 598 599 /* Perform section-specific processing */ 600 switch (state) { 601 case KRL_SECTION_CERT_SERIAL_LIST: 602 for (i = 0; i < contig; i++) 603 buffer_put_int64(§, rs->lo + i); 604 break; 605 case KRL_SECTION_CERT_SERIAL_RANGE: 606 buffer_put_int64(§, rs->lo); 607 buffer_put_int64(§, rs->hi); 608 break; 609 case KRL_SECTION_CERT_SERIAL_BITMAP: 610 if (rs->lo - bitmap_start > INT_MAX) { 611 error("%s: insane bitmap gap", __func__); 612 goto out; 613 } 614 for (i = 0; i < contig; i++) { 615 if (BN_set_bit(bitmap, 616 rs->lo + i - bitmap_start) != 1) 617 goto out; 618 } 619 break; 620 } 621 last = rs->hi; 622 } 623 /* Flush the remaining section, if any */ 624 if (state != 0) { 625 debug3("%s: serial final flush for state 0x%02x", 626 __func__, state); 627 switch (state) { 628 case KRL_SECTION_CERT_SERIAL_LIST: 629 case KRL_SECTION_CERT_SERIAL_RANGE: 630 break; 631 case KRL_SECTION_CERT_SERIAL_BITMAP: 632 buffer_put_bignum2(§, bitmap); 633 BN_free(bitmap); 634 bitmap = NULL; 635 break; 636 } 637 buffer_put_char(buf, state); 638 buffer_put_string(buf, 639 buffer_ptr(§), buffer_len(§)); 640 } 641 debug3("%s: serial done ", __func__); 642 643 /* Now output a section for any revocations by key ID */ 644 buffer_clear(§); 645 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { 646 debug3("%s: key ID %s", __func__, rki->key_id); 647 buffer_put_cstring(§, rki->key_id); 648 } 649 if (buffer_len(§) != 0) { 650 buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID); 651 buffer_put_string(buf, buffer_ptr(§), 652 buffer_len(§)); 653 } 654 r = 0; 655 out: 656 if (bitmap != NULL) 657 BN_free(bitmap); 658 buffer_free(§); 659 return r; 660 } 661 662 int 663 ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys, 664 u_int nsign_keys) 665 { 666 int r = -1; 667 struct revoked_certs *rc; 668 struct revoked_blob *rb; 669 Buffer sect; 670 u_char *kblob = NULL, *sblob = NULL; 671 u_int klen, slen, i; 672 673 if (krl->generated_date == 0) 674 krl->generated_date = time(NULL); 675 676 buffer_init(§); 677 678 /* Store the header */ 679 buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1); 680 buffer_put_int(buf, KRL_FORMAT_VERSION); 681 buffer_put_int64(buf, krl->krl_version); 682 buffer_put_int64(buf, krl->generated_date); 683 buffer_put_int64(buf, krl->flags); 684 buffer_put_string(buf, NULL, 0); 685 buffer_put_cstring(buf, krl->comment ? krl->comment : ""); 686 687 /* Store sections for revoked certificates */ 688 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 689 if (revoked_certs_generate(rc, §) != 0) 690 goto out; 691 buffer_put_char(buf, KRL_SECTION_CERTIFICATES); 692 buffer_put_string(buf, buffer_ptr(§), 693 buffer_len(§)); 694 } 695 696 /* Finally, output sections for revocations by public key/hash */ 697 buffer_clear(§); 698 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { 699 debug3("%s: key len %u ", __func__, rb->len); 700 buffer_put_string(§, rb->blob, rb->len); 701 } 702 if (buffer_len(§) != 0) { 703 buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY); 704 buffer_put_string(buf, buffer_ptr(§), 705 buffer_len(§)); 706 } 707 buffer_clear(§); 708 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { 709 debug3("%s: hash len %u ", __func__, rb->len); 710 buffer_put_string(§, rb->blob, rb->len); 711 } 712 if (buffer_len(§) != 0) { 713 buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1); 714 buffer_put_string(buf, buffer_ptr(§), 715 buffer_len(§)); 716 } 717 718 for (i = 0; i < nsign_keys; i++) { 719 if (key_to_blob(sign_keys[i], &kblob, &klen) == 0) 720 goto out; 721 722 debug3("%s: signature key len %u", __func__, klen); 723 buffer_put_char(buf, KRL_SECTION_SIGNATURE); 724 buffer_put_string(buf, kblob, klen); 725 726 if (key_sign(sign_keys[i], &sblob, &slen, 727 buffer_ptr(buf), buffer_len(buf)) == -1) 728 goto out; 729 debug3("%s: signature sig len %u", __func__, slen); 730 buffer_put_string(buf, sblob, slen); 731 } 732 733 r = 0; 734 out: 735 free(kblob); 736 free(sblob); 737 buffer_free(§); 738 return r; 739 } 740 741 static void 742 format_timestamp(u_int64_t timestamp, char *ts, size_t nts) 743 { 744 time_t t; 745 struct tm *tm; 746 747 t = timestamp; 748 tm = localtime(&t); 749 *ts = '\0'; 750 strftime(ts, nts, "%Y%m%dT%H%M%S", tm); 751 } 752 753 static int 754 parse_revoked_certs(Buffer *buf, struct ssh_krl *krl) 755 { 756 int ret = -1, nbits; 757 u_char type; 758 const u_char *blob; 759 u_int blen; 760 Buffer subsect; 761 u_int64_t serial, serial_lo, serial_hi; 762 BIGNUM *bitmap = NULL; 763 char *key_id = NULL; 764 Key *ca_key = NULL; 765 766 buffer_init(&subsect); 767 768 if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL || 769 buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */ 770 error("%s: buffer error", __func__); 771 goto out; 772 } 773 if ((ca_key = key_from_blob(blob, blen)) == NULL) 774 goto out; 775 776 while (buffer_len(buf) > 0) { 777 if (buffer_get_char_ret(&type, buf) != 0 || 778 (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) { 779 error("%s: buffer error", __func__); 780 goto out; 781 } 782 buffer_clear(&subsect); 783 buffer_append(&subsect, blob, blen); 784 debug3("%s: subsection type 0x%02x", __func__, type); 785 /* buffer_dump(&subsect); */ 786 787 switch (type) { 788 case KRL_SECTION_CERT_SERIAL_LIST: 789 while (buffer_len(&subsect) > 0) { 790 if (buffer_get_int64_ret(&serial, 791 &subsect) != 0) { 792 error("%s: buffer error", __func__); 793 goto out; 794 } 795 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 796 serial) != 0) { 797 error("%s: update failed", __func__); 798 goto out; 799 } 800 } 801 break; 802 case KRL_SECTION_CERT_SERIAL_RANGE: 803 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 804 buffer_get_int64_ret(&serial_hi, &subsect) != 0) { 805 error("%s: buffer error", __func__); 806 goto out; 807 } 808 if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key, 809 serial_lo, serial_hi) != 0) { 810 error("%s: update failed", __func__); 811 goto out; 812 } 813 break; 814 case KRL_SECTION_CERT_SERIAL_BITMAP: 815 if ((bitmap = BN_new()) == NULL) { 816 error("%s: BN_new", __func__); 817 goto out; 818 } 819 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 820 buffer_get_bignum2_ret(&subsect, bitmap) != 0) { 821 error("%s: buffer error", __func__); 822 goto out; 823 } 824 if ((nbits = BN_num_bits(bitmap)) < 0) { 825 error("%s: bitmap bits < 0", __func__); 826 goto out; 827 } 828 for (serial = 0; serial < (u_int)nbits; serial++) { 829 if (serial > 0 && serial_lo + serial == 0) { 830 error("%s: bitmap wraps u64", __func__); 831 goto out; 832 } 833 if (!BN_is_bit_set(bitmap, serial)) 834 continue; 835 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 836 serial_lo + serial) != 0) { 837 error("%s: update failed", __func__); 838 goto out; 839 } 840 } 841 BN_free(bitmap); 842 bitmap = NULL; 843 break; 844 case KRL_SECTION_CERT_KEY_ID: 845 while (buffer_len(&subsect) > 0) { 846 if ((key_id = buffer_get_cstring_ret(&subsect, 847 NULL)) == NULL) { 848 error("%s: buffer error", __func__); 849 goto out; 850 } 851 if (ssh_krl_revoke_cert_by_key_id(krl, ca_key, 852 key_id) != 0) { 853 error("%s: update failed", __func__); 854 goto out; 855 } 856 free(key_id); 857 key_id = NULL; 858 } 859 break; 860 default: 861 error("Unsupported KRL certificate section %u", type); 862 goto out; 863 } 864 if (buffer_len(&subsect) > 0) { 865 error("KRL certificate section contains unparsed data"); 866 goto out; 867 } 868 } 869 870 ret = 0; 871 out: 872 if (ca_key != NULL) 873 key_free(ca_key); 874 if (bitmap != NULL) 875 BN_free(bitmap); 876 free(key_id); 877 buffer_free(&subsect); 878 return ret; 879 } 880 881 882 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */ 883 int 884 ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp, 885 const Key **sign_ca_keys, u_int nsign_ca_keys) 886 { 887 Buffer copy, sect; 888 struct ssh_krl *krl; 889 char timestamp[64]; 890 int ret = -1, r, sig_seen; 891 Key *key = NULL, **ca_used = NULL; 892 u_char type, *rdata = NULL; 893 const u_char *blob; 894 u_int i, j, sig_off, sects_off, rlen, blen, format_version, nca_used; 895 896 nca_used = 0; 897 *krlp = NULL; 898 if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 || 899 memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) { 900 debug3("%s: not a KRL", __func__); 901 /* 902 * Return success but a NULL *krlp here to signal that the 903 * file might be a simple list of keys. 904 */ 905 return 0; 906 } 907 908 /* Take a copy of the KRL buffer so we can verify its signature later */ 909 buffer_init(©); 910 buffer_append(©, buffer_ptr(buf), buffer_len(buf)); 911 912 buffer_init(§); 913 buffer_consume(©, sizeof(KRL_MAGIC) - 1); 914 915 if ((krl = ssh_krl_init()) == NULL) { 916 error("%s: alloc failed", __func__); 917 goto out; 918 } 919 920 if (buffer_get_int_ret(&format_version, ©) != 0) { 921 error("%s: KRL truncated", __func__); 922 goto out; 923 } 924 if (format_version != KRL_FORMAT_VERSION) { 925 error("%s: KRL unsupported format version %u", 926 __func__, format_version); 927 goto out; 928 } 929 if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 || 930 buffer_get_int64_ret(&krl->generated_date, ©) != 0 || 931 buffer_get_int64_ret(&krl->flags, ©) != 0 || 932 buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */ 933 (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) { 934 error("%s: buffer error", __func__); 935 goto out; 936 } 937 938 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); 939 debug("KRL version %llu generated at %s%s%s", 940 (long long unsigned)krl->krl_version, timestamp, 941 *krl->comment ? ": " : "", krl->comment); 942 943 /* 944 * 1st pass: verify signatures, if any. This is done to avoid 945 * detailed parsing of data whose provenance is unverified. 946 */ 947 sig_seen = 0; 948 sects_off = buffer_len(buf) - buffer_len(©); 949 while (buffer_len(©) > 0) { 950 if (buffer_get_char_ret(&type, ©) != 0 || 951 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 952 error("%s: buffer error", __func__); 953 goto out; 954 } 955 debug3("%s: first pass, section 0x%02x", __func__, type); 956 if (type != KRL_SECTION_SIGNATURE) { 957 if (sig_seen) { 958 error("KRL contains non-signature section " 959 "after signature"); 960 goto out; 961 } 962 /* Not interested for now. */ 963 continue; 964 } 965 sig_seen = 1; 966 /* First string component is the signing key */ 967 if ((key = key_from_blob(blob, blen)) == NULL) { 968 error("%s: invalid signature key", __func__); 969 goto out; 970 } 971 sig_off = buffer_len(buf) - buffer_len(©); 972 /* Second string component is the signature itself */ 973 if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 974 error("%s: buffer error", __func__); 975 goto out; 976 } 977 /* Check signature over entire KRL up to this point */ 978 if (key_verify(key, blob, blen, 979 buffer_ptr(buf), buffer_len(buf) - sig_off) != 1) { 980 error("bad signaure on KRL"); 981 goto out; 982 } 983 /* Check if this key has already signed this KRL */ 984 for (i = 0; i < nca_used; i++) { 985 if (key_equal(ca_used[i], key)) { 986 error("KRL signed more than once with " 987 "the same key"); 988 goto out; 989 } 990 } 991 /* Record keys used to sign the KRL */ 992 ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used)); 993 ca_used[nca_used++] = key; 994 key = NULL; 995 break; 996 } 997 998 /* 999 * 2nd pass: parse and load the KRL, skipping the header to the point 1000 * where the section start. 1001 */ 1002 buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off, 1003 buffer_len(buf) - sects_off); 1004 while (buffer_len(©) > 0) { 1005 if (buffer_get_char_ret(&type, ©) != 0 || 1006 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 1007 error("%s: buffer error", __func__); 1008 goto out; 1009 } 1010 debug3("%s: second pass, section 0x%02x", __func__, type); 1011 buffer_clear(§); 1012 buffer_append(§, blob, blen); 1013 1014 switch (type) { 1015 case KRL_SECTION_CERTIFICATES: 1016 if ((r = parse_revoked_certs(§, krl)) != 0) 1017 goto out; 1018 break; 1019 case KRL_SECTION_EXPLICIT_KEY: 1020 case KRL_SECTION_FINGERPRINT_SHA1: 1021 while (buffer_len(§) > 0) { 1022 if ((rdata = buffer_get_string_ret(§, 1023 &rlen)) == NULL) { 1024 error("%s: buffer error", __func__); 1025 goto out; 1026 } 1027 if (type == KRL_SECTION_FINGERPRINT_SHA1 && 1028 rlen != 20) { 1029 error("%s: bad SHA1 length", __func__); 1030 goto out; 1031 } 1032 if (revoke_blob( 1033 type == KRL_SECTION_EXPLICIT_KEY ? 1034 &krl->revoked_keys : &krl->revoked_sha1s, 1035 rdata, rlen) != 0) 1036 goto out; 1037 rdata = NULL; /* 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 free(rdata); 1104 if (key != NULL) 1105 key_free(key); 1106 buffer_free(©); 1107 buffer_free(§); 1108 return ret; 1109 } 1110 1111 /* Checks whether a given key/cert is revoked. Does not check its CA */ 1112 static int 1113 is_key_revoked(struct ssh_krl *krl, const Key *key) 1114 { 1115 struct revoked_blob rb, *erb; 1116 struct revoked_serial rs, *ers; 1117 struct revoked_key_id rki, *erki; 1118 struct revoked_certs *rc; 1119 1120 /* Check explicitly revoked hashes first */ 1121 memset(&rb, 0, sizeof(rb)); 1122 if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL) 1123 return -1; 1124 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb); 1125 free(rb.blob); 1126 if (erb != NULL) { 1127 debug("%s: revoked by key SHA1", __func__); 1128 return -1; 1129 } 1130 1131 /* Next, explicit keys */ 1132 memset(&rb, 0, sizeof(rb)); 1133 if (plain_key_blob(key, &rb.blob, &rb.len) < 0) 1134 return -1; 1135 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb); 1136 free(rb.blob); 1137 if (erb != NULL) { 1138 debug("%s: revoked by explicit key", __func__); 1139 return -1; 1140 } 1141 1142 if (!key_is_cert(key)) 1143 return 0; 1144 1145 /* Check cert revocation */ 1146 if (revoked_certs_for_ca_key(krl, key->cert->signature_key, 1147 &rc, 0) != 0) 1148 return -1; 1149 if (rc == NULL) 1150 return 0; /* No entry for this CA */ 1151 1152 /* Check revocation by cert key ID */ 1153 memset(&rki, 0, sizeof(rki)); 1154 rki.key_id = key->cert->key_id; 1155 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki); 1156 if (erki != NULL) { 1157 debug("%s: revoked by key ID", __func__); 1158 return -1; 1159 } 1160 1161 /* 1162 * Legacy cert formats lack serial numbers. Zero serials numbers 1163 * are ignored (it's the default when the CA doesn't specify one). 1164 */ 1165 if (key_cert_is_legacy(key) || key->cert->serial == 0) 1166 return 0; 1167 1168 memset(&rs, 0, sizeof(rs)); 1169 rs.lo = rs.hi = key->cert->serial; 1170 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs); 1171 if (ers != NULL) { 1172 KRL_DBG(("%s: %llu matched %llu:%llu", __func__, 1173 key->cert->serial, ers->lo, ers->hi)); 1174 debug("%s: revoked by serial", __func__); 1175 return -1; 1176 } 1177 KRL_DBG(("%s: %llu no match", __func__, key->cert->serial)); 1178 1179 return 0; 1180 } 1181 1182 int 1183 ssh_krl_check_key(struct ssh_krl *krl, const Key *key) 1184 { 1185 int r; 1186 1187 debug2("%s: checking key", __func__); 1188 if ((r = is_key_revoked(krl, key)) != 0) 1189 return r; 1190 if (key_is_cert(key)) { 1191 debug2("%s: checking CA key", __func__); 1192 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0) 1193 return r; 1194 } 1195 debug3("%s: key okay", __func__); 1196 return 0; 1197 } 1198 1199 /* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */ 1200 int 1201 ssh_krl_file_contains_key(const char *path, const Key *key) 1202 { 1203 Buffer krlbuf; 1204 struct ssh_krl *krl; 1205 int revoked, fd; 1206 1207 if (path == NULL) 1208 return 0; 1209 1210 if ((fd = open(path, O_RDONLY)) == -1) { 1211 error("open %s: %s", path, strerror(errno)); 1212 error("Revoked keys file not accessible - refusing public key " 1213 "authentication"); 1214 return -1; 1215 } 1216 buffer_init(&krlbuf); 1217 if (!key_load_file(fd, path, &krlbuf)) { 1218 close(fd); 1219 buffer_free(&krlbuf); 1220 error("Revoked keys file not readable - refusing public key " 1221 "authentication"); 1222 return -1; 1223 } 1224 close(fd); 1225 if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) { 1226 buffer_free(&krlbuf); 1227 error("Invalid KRL, refusing public key " 1228 "authentication"); 1229 return -1; 1230 } 1231 buffer_free(&krlbuf); 1232 if (krl == NULL) { 1233 debug3("%s: %s is not a KRL file", __func__, path); 1234 return -2; 1235 } 1236 debug2("%s: checking KRL %s", __func__, path); 1237 revoked = ssh_krl_check_key(krl, key) != 0; 1238 ssh_krl_free(krl); 1239 return revoked ? -1 : 0; 1240 } 1241