1 /* $NetBSD: krl.c,v 1.3 2013/11/08 19:18:25 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 1.13 2013/07/20 22:20:42 djm Exp $ */ 19 #include <sys/cdefs.h> 20 __RCSID("$NetBSD: krl.c,v 1.3 2013/11/08 19:18:25 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 "misc.h" 39 #include "log.h" 40 #include "xmalloc.h" 41 42 #include "krl.h" 43 44 /* #define DEBUG_KRL */ 45 #ifdef DEBUG_KRL 46 # define KRL_DBG(x) debug3 x 47 #else 48 # define KRL_DBG(x) 49 #endif 50 51 /* 52 * Trees of revoked serial numbers, key IDs and keys. This allows 53 * quick searching, querying and producing lists in canonical order. 54 */ 55 56 /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */ 57 struct revoked_serial { 58 u_int64_t lo, hi; 59 RB_ENTRY(revoked_serial) tree_entry; 60 }; 61 static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b); 62 RB_HEAD(revoked_serial_tree, revoked_serial); 63 RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp); 64 65 /* Tree of key IDs */ 66 struct revoked_key_id { 67 char *key_id; 68 RB_ENTRY(revoked_key_id) tree_entry; 69 }; 70 static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b); 71 RB_HEAD(revoked_key_id_tree, revoked_key_id); 72 RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp); 73 74 /* Tree of blobs (used for keys and fingerprints) */ 75 struct revoked_blob { 76 u_char *blob; 77 u_int len; 78 RB_ENTRY(revoked_blob) tree_entry; 79 }; 80 static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b); 81 RB_HEAD(revoked_blob_tree, revoked_blob); 82 RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp); 83 84 /* Tracks revoked certs for a single CA */ 85 struct revoked_certs { 86 Key *ca_key; 87 struct revoked_serial_tree revoked_serials; 88 struct revoked_key_id_tree revoked_key_ids; 89 TAILQ_ENTRY(revoked_certs) entry; 90 }; 91 TAILQ_HEAD(revoked_certs_list, revoked_certs); 92 93 struct ssh_krl { 94 u_int64_t krl_version; 95 u_int64_t generated_date; 96 u_int64_t flags; 97 char *comment; 98 struct revoked_blob_tree revoked_keys; 99 struct revoked_blob_tree revoked_sha1s; 100 struct revoked_certs_list revoked_certs; 101 }; 102 103 /* Return equal if a and b overlap */ 104 static int 105 serial_cmp(struct revoked_serial *a, struct revoked_serial *b) 106 { 107 if (a->hi >= b->lo && a->lo <= b->hi) 108 return 0; 109 return a->lo < b->lo ? -1 : 1; 110 } 111 112 static int 113 key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b) 114 { 115 return strcmp(a->key_id, b->key_id); 116 } 117 118 static int 119 blob_cmp(struct revoked_blob *a, struct revoked_blob *b) 120 { 121 int r; 122 123 if (a->len != b->len) { 124 if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0) 125 return r; 126 return a->len > b->len ? 1 : -1; 127 } else 128 return memcmp(a->blob, b->blob, a->len); 129 } 130 131 struct ssh_krl * 132 ssh_krl_init(void) 133 { 134 struct ssh_krl *krl; 135 136 if ((krl = calloc(1, sizeof(*krl))) == NULL) 137 return NULL; 138 RB_INIT(&krl->revoked_keys); 139 RB_INIT(&krl->revoked_sha1s); 140 TAILQ_INIT(&krl->revoked_certs); 141 return krl; 142 } 143 144 static void 145 revoked_certs_free(struct revoked_certs *rc) 146 { 147 struct revoked_serial *rs, *trs; 148 struct revoked_key_id *rki, *trki; 149 150 RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) { 151 RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs); 152 free(rs); 153 } 154 RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) { 155 RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki); 156 free(rki->key_id); 157 free(rki); 158 } 159 if (rc->ca_key != NULL) 160 key_free(rc->ca_key); 161 } 162 163 void 164 ssh_krl_free(struct ssh_krl *krl) 165 { 166 struct revoked_blob *rb, *trb; 167 struct revoked_certs *rc, *trc; 168 169 if (krl == NULL) 170 return; 171 172 free(krl->comment); 173 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) { 174 RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb); 175 free(rb->blob); 176 free(rb); 177 } 178 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) { 179 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb); 180 free(rb->blob); 181 free(rb); 182 } 183 TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) { 184 TAILQ_REMOVE(&krl->revoked_certs, rc, entry); 185 revoked_certs_free(rc); 186 } 187 } 188 189 void 190 ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version) 191 { 192 krl->krl_version = version; 193 } 194 195 void 196 ssh_krl_set_comment(struct ssh_krl *krl, const char *comment) 197 { 198 free(krl->comment); 199 if ((krl->comment = strdup(comment)) == NULL) 200 fatal("%s: strdup", __func__); 201 } 202 203 /* 204 * Find the revoked_certs struct for a CA key. If allow_create is set then 205 * create a new one in the tree if one did not exist already. 206 */ 207 static int 208 revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key, 209 struct revoked_certs **rcp, int allow_create) 210 { 211 struct revoked_certs *rc; 212 213 *rcp = NULL; 214 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 215 if (key_equal(rc->ca_key, ca_key)) { 216 *rcp = rc; 217 return 0; 218 } 219 } 220 if (!allow_create) 221 return 0; 222 /* If this CA doesn't exist in the list then add it now */ 223 if ((rc = calloc(1, sizeof(*rc))) == NULL) 224 return -1; 225 if ((rc->ca_key = key_from_private(ca_key)) == NULL) { 226 free(rc); 227 return -1; 228 } 229 RB_INIT(&rc->revoked_serials); 230 RB_INIT(&rc->revoked_key_ids); 231 TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry); 232 debug3("%s: new CA %s", __func__, key_type(ca_key)); 233 *rcp = rc; 234 return 0; 235 } 236 237 static int 238 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi) 239 { 240 struct revoked_serial rs, *ers, *crs, *irs; 241 242 KRL_DBG(("%s: insert %"PRIu64":%"PRIu64, __func__, lo, hi)); 243 bzero(&rs, sizeof(rs)); 244 rs.lo = lo; 245 rs.hi = hi; 246 ers = RB_NFIND(revoked_serial_tree, rt, &rs); 247 if (ers == NULL || serial_cmp(ers, &rs) != 0) { 248 /* No entry matches. Just insert */ 249 if ((irs = malloc(sizeof(rs))) == NULL) 250 return -1; 251 memcpy(irs, &rs, sizeof(*irs)); 252 ers = RB_INSERT(revoked_serial_tree, rt, irs); 253 if (ers != NULL) { 254 KRL_DBG(("%s: bad: ers != NULL", __func__)); 255 /* Shouldn't happen */ 256 free(irs); 257 return -1; 258 } 259 ers = irs; 260 } else { 261 KRL_DBG(("%s: overlap found %"PRIu64":%"PRIu64, __func__, 262 ers->lo, ers->hi)); 263 /* 264 * The inserted entry overlaps an existing one. Grow the 265 * existing entry. 266 */ 267 if (ers->lo > lo) 268 ers->lo = lo; 269 if (ers->hi < hi) 270 ers->hi = hi; 271 } 272 /* 273 * The inserted or revised range might overlap or abut adjacent ones; 274 * coalesce as necessary. 275 */ 276 277 /* Check predecessors */ 278 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) { 279 KRL_DBG(("%s: pred %"PRIu64":%"PRIu64, __func__, 280 crs->lo, crs->hi)); 281 if (ers->lo != 0 && crs->hi < ers->lo - 1) 282 break; 283 /* This entry overlaps. */ 284 if (crs->lo < ers->lo) { 285 ers->lo = crs->lo; 286 KRL_DBG(("%s: pred extend %"PRIu64":%"PRIu64, __func__, 287 ers->lo, ers->hi)); 288 } 289 RB_REMOVE(revoked_serial_tree, rt, crs); 290 free(crs); 291 } 292 /* Check successors */ 293 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) { 294 KRL_DBG(("%s: succ %"PRIu64":%"PRIu64, __func__, crs->lo, 295 crs->hi)); 296 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1) 297 break; 298 /* This entry overlaps. */ 299 if (crs->hi > ers->hi) { 300 ers->hi = crs->hi; 301 KRL_DBG(("%s: succ extend %"PRIu64":%"PRIu64, __func__, 302 ers->lo, ers->hi)); 303 } 304 RB_REMOVE(revoked_serial_tree, rt, crs); 305 free(crs); 306 } 307 KRL_DBG(("%s: done, final %"PRIu64":%"PRIu64, __func__, ers->lo, 308 ers->hi)); 309 return 0; 310 } 311 312 int 313 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key, 314 u_int64_t serial) 315 { 316 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial); 317 } 318 319 int 320 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key, 321 u_int64_t lo, u_int64_t hi) 322 { 323 struct revoked_certs *rc; 324 325 if (lo > hi || lo == 0) 326 return -1; 327 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 328 return -1; 329 return insert_serial_range(&rc->revoked_serials, lo, hi); 330 } 331 332 int 333 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key, 334 const char *key_id) 335 { 336 struct revoked_key_id *rki, *erki; 337 struct revoked_certs *rc; 338 339 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) 340 return -1; 341 342 debug3("%s: revoke %s", __func__, key_id); 343 if ((rki = calloc(1, sizeof(*rki))) == NULL || 344 (rki->key_id = strdup(key_id)) == NULL) { 345 free(rki); 346 fatal("%s: strdup", __func__); 347 } 348 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki); 349 if (erki != NULL) { 350 free(rki->key_id); 351 free(rki); 352 } 353 return 0; 354 } 355 356 /* Convert "key" to a public key blob without any certificate information */ 357 static int 358 plain_key_blob(const Key *key, u_char **blob, u_int *blen) 359 { 360 Key *kcopy; 361 int r; 362 363 if ((kcopy = key_from_private(key)) == NULL) 364 return -1; 365 if (key_is_cert(kcopy)) { 366 if (key_drop_cert(kcopy) != 0) { 367 error("%s: key_drop_cert", __func__); 368 key_free(kcopy); 369 return -1; 370 } 371 } 372 r = key_to_blob(kcopy, blob, blen); 373 free(kcopy); 374 return r == 0 ? -1 : 0; 375 } 376 377 /* Revoke a key blob. Ownership of blob is transferred to the tree */ 378 static int 379 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len) 380 { 381 struct revoked_blob *rb, *erb; 382 383 if ((rb = calloc(1, sizeof(*rb))) == NULL) 384 return -1; 385 rb->blob = blob; 386 rb->len = len; 387 erb = RB_INSERT(revoked_blob_tree, rbt, rb); 388 if (erb != NULL) { 389 free(rb->blob); 390 free(rb); 391 } 392 return 0; 393 } 394 395 int 396 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key) 397 { 398 u_char *blob; 399 u_int len; 400 401 debug3("%s: revoke type %s", __func__, key_type(key)); 402 if (plain_key_blob(key, &blob, &len) != 0) 403 return -1; 404 return revoke_blob(&krl->revoked_keys, blob, len); 405 } 406 407 int 408 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key) 409 { 410 u_char *blob; 411 u_int len; 412 413 debug3("%s: revoke type %s by sha1", __func__, key_type(key)); 414 if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL) 415 return -1; 416 return revoke_blob(&krl->revoked_sha1s, blob, len); 417 } 418 419 int 420 ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key) 421 { 422 if (!key_is_cert(key)) 423 return ssh_krl_revoke_key_sha1(krl, key); 424 425 if (key_cert_is_legacy(key) || key->cert->serial == 0) { 426 return ssh_krl_revoke_cert_by_key_id(krl, 427 key->cert->signature_key, 428 key->cert->key_id); 429 } else { 430 return ssh_krl_revoke_cert_by_serial(krl, 431 key->cert->signature_key, 432 key->cert->serial); 433 } 434 } 435 436 /* 437 * Select a copact next section type to emit in a KRL based on the 438 * current section type, the run length of contiguous revoked serial 439 * numbers and the gaps from the last and to the next revoked serial. 440 * Applies a mostly-accurate bit cost model to select the section type 441 * that will minimise the size of the resultant KRL. 442 */ 443 static int 444 choose_next_state(int current_state, u_int64_t contig, int final, 445 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section) 446 { 447 int new_state; 448 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart; 449 450 /* 451 * Avoid unsigned overflows. 452 * The limits are high enough to avoid confusing the calculations. 453 */ 454 contig = MIN(contig, 1ULL<<31); 455 last_gap = MIN(last_gap, 1ULL<<31); 456 next_gap = MIN(next_gap, 1ULL<<31); 457 458 /* 459 * Calculate the cost to switch from the current state to candidates. 460 * NB. range sections only ever contain a single range, so their 461 * switching cost is independent of the current_state. 462 */ 463 cost_list = cost_bitmap = cost_bitmap_restart = 0; 464 cost_range = 8; 465 switch (current_state) { 466 case KRL_SECTION_CERT_SERIAL_LIST: 467 cost_bitmap_restart = cost_bitmap = 8 + 64; 468 break; 469 case KRL_SECTION_CERT_SERIAL_BITMAP: 470 cost_list = 8; 471 cost_bitmap_restart = 8 + 64; 472 break; 473 case KRL_SECTION_CERT_SERIAL_RANGE: 474 case 0: 475 cost_bitmap_restart = cost_bitmap = 8 + 64; 476 cost_list = 8; 477 } 478 479 /* Estimate base cost in bits of each section type */ 480 cost_list += 64 * contig + (final ? 0 : 8+64); 481 cost_range += (2 * 64) + (final ? 0 : 8+64); 482 cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64)); 483 cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64)); 484 485 /* Convert to byte costs for actual comparison */ 486 cost_list = (cost_list + 7) / 8; 487 cost_bitmap = (cost_bitmap + 7) / 8; 488 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8; 489 cost_range = (cost_range + 7) / 8; 490 491 /* Now pick the best choice */ 492 *force_new_section = 0; 493 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 494 cost = cost_bitmap; 495 if (cost_range < cost) { 496 new_state = KRL_SECTION_CERT_SERIAL_RANGE; 497 cost = cost_range; 498 } 499 if (cost_list < cost) { 500 new_state = KRL_SECTION_CERT_SERIAL_LIST; 501 cost = cost_list; 502 } 503 if (cost_bitmap_restart < cost) { 504 new_state = KRL_SECTION_CERT_SERIAL_BITMAP; 505 *force_new_section = 1; 506 cost = cost_bitmap_restart; 507 } 508 debug3("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:" 509 "list %llu range %llu bitmap %llu new bitmap %llu, " 510 "selected 0x%02x%s", __func__, (long long unsigned)contig, 511 (long long unsigned)last_gap, (long long unsigned)next_gap, final, 512 (long long unsigned)cost_list, (long long unsigned)cost_range, 513 (long long unsigned)cost_bitmap, 514 (long long unsigned)cost_bitmap_restart, new_state, 515 *force_new_section ? " restart" : ""); 516 return new_state; 517 } 518 519 /* Generate a KRL_SECTION_CERTIFICATES KRL section */ 520 static int 521 revoked_certs_generate(struct revoked_certs *rc, Buffer *buf) 522 { 523 int final, force_new_sect, r = -1; 524 u_int64_t i, contig, gap, last = 0, bitmap_start = 0; 525 struct revoked_serial *rs, *nrs; 526 struct revoked_key_id *rki; 527 int next_state, state = 0; 528 Buffer sect; 529 u_char *kblob = NULL; 530 u_int klen; 531 BIGNUM *bitmap = NULL; 532 533 /* Prepare CA scope key blob if we have one supplied */ 534 if (key_to_blob(rc->ca_key, &kblob, &klen) == 0) 535 return -1; 536 537 buffer_init(§); 538 539 /* Store the header */ 540 buffer_put_string(buf, kblob, klen); 541 buffer_put_string(buf, NULL, 0); /* Reserved */ 542 543 free(kblob); 544 545 /* Store the revoked serials. */ 546 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials); 547 rs != NULL; 548 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) { 549 debug3("%s: serial %llu:%llu state 0x%02x", __func__, 550 (long long unsigned)rs->lo, (long long unsigned)rs->hi, 551 state); 552 553 /* Check contiguous length and gap to next section (if any) */ 554 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs); 555 final = nrs == NULL; 556 gap = nrs == NULL ? 0 : nrs->lo - rs->hi; 557 contig = 1 + (rs->hi - rs->lo); 558 559 /* Choose next state based on these */ 560 next_state = choose_next_state(state, contig, final, 561 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect); 562 563 /* 564 * If the current section is a range section or has a different 565 * type to the next section, then finish it off now. 566 */ 567 if (state != 0 && (force_new_sect || next_state != state || 568 state == KRL_SECTION_CERT_SERIAL_RANGE)) { 569 debug3("%s: finish state 0x%02x", __func__, state); 570 switch (state) { 571 case KRL_SECTION_CERT_SERIAL_LIST: 572 case KRL_SECTION_CERT_SERIAL_RANGE: 573 break; 574 case KRL_SECTION_CERT_SERIAL_BITMAP: 575 buffer_put_bignum2(§, bitmap); 576 BN_free(bitmap); 577 bitmap = NULL; 578 break; 579 } 580 buffer_put_char(buf, state); 581 buffer_put_string(buf, 582 buffer_ptr(§), buffer_len(§)); 583 } 584 585 /* If we are starting a new section then prepare it now */ 586 if (next_state != state || force_new_sect) { 587 debug3("%s: start state 0x%02x", __func__, next_state); 588 state = next_state; 589 buffer_clear(§); 590 switch (state) { 591 case KRL_SECTION_CERT_SERIAL_LIST: 592 case KRL_SECTION_CERT_SERIAL_RANGE: 593 break; 594 case KRL_SECTION_CERT_SERIAL_BITMAP: 595 if ((bitmap = BN_new()) == NULL) 596 goto out; 597 bitmap_start = rs->lo; 598 buffer_put_int64(§, bitmap_start); 599 break; 600 } 601 } 602 603 /* Perform section-specific processing */ 604 switch (state) { 605 case KRL_SECTION_CERT_SERIAL_LIST: 606 for (i = 0; i < contig; i++) 607 buffer_put_int64(§, rs->lo + i); 608 break; 609 case KRL_SECTION_CERT_SERIAL_RANGE: 610 buffer_put_int64(§, rs->lo); 611 buffer_put_int64(§, rs->hi); 612 break; 613 case KRL_SECTION_CERT_SERIAL_BITMAP: 614 if (rs->lo - bitmap_start > INT_MAX) { 615 error("%s: insane bitmap gap", __func__); 616 goto out; 617 } 618 for (i = 0; i < contig; i++) { 619 if (BN_set_bit(bitmap, 620 rs->lo + i - bitmap_start) != 1) 621 goto out; 622 } 623 break; 624 } 625 last = rs->hi; 626 } 627 /* Flush the remaining section, if any */ 628 if (state != 0) { 629 debug3("%s: serial final flush for state 0x%02x", 630 __func__, state); 631 switch (state) { 632 case KRL_SECTION_CERT_SERIAL_LIST: 633 case KRL_SECTION_CERT_SERIAL_RANGE: 634 break; 635 case KRL_SECTION_CERT_SERIAL_BITMAP: 636 buffer_put_bignum2(§, bitmap); 637 BN_free(bitmap); 638 bitmap = NULL; 639 break; 640 } 641 buffer_put_char(buf, state); 642 buffer_put_string(buf, 643 buffer_ptr(§), buffer_len(§)); 644 } 645 debug3("%s: serial done ", __func__); 646 647 /* Now output a section for any revocations by key ID */ 648 buffer_clear(§); 649 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { 650 debug3("%s: key ID %s", __func__, rki->key_id); 651 buffer_put_cstring(§, rki->key_id); 652 } 653 if (buffer_len(§) != 0) { 654 buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID); 655 buffer_put_string(buf, buffer_ptr(§), 656 buffer_len(§)); 657 } 658 r = 0; 659 out: 660 if (bitmap != NULL) 661 BN_free(bitmap); 662 buffer_free(§); 663 return r; 664 } 665 666 int 667 ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys, 668 u_int nsign_keys) 669 { 670 int r = -1; 671 struct revoked_certs *rc; 672 struct revoked_blob *rb; 673 Buffer sect; 674 u_char *kblob = NULL, *sblob = NULL; 675 u_int klen, slen, i; 676 677 if (krl->generated_date == 0) 678 krl->generated_date = time(NULL); 679 680 buffer_init(§); 681 682 /* Store the header */ 683 buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1); 684 buffer_put_int(buf, KRL_FORMAT_VERSION); 685 buffer_put_int64(buf, krl->krl_version); 686 buffer_put_int64(buf, krl->generated_date); 687 buffer_put_int64(buf, krl->flags); 688 buffer_put_string(buf, NULL, 0); 689 buffer_put_cstring(buf, krl->comment ? krl->comment : ""); 690 691 /* Store sections for revoked certificates */ 692 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { 693 if (revoked_certs_generate(rc, §) != 0) 694 goto out; 695 buffer_put_char(buf, KRL_SECTION_CERTIFICATES); 696 buffer_put_string(buf, buffer_ptr(§), 697 buffer_len(§)); 698 } 699 700 /* Finally, output sections for revocations by public key/hash */ 701 buffer_clear(§); 702 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { 703 debug3("%s: key len %u ", __func__, rb->len); 704 buffer_put_string(§, rb->blob, rb->len); 705 } 706 if (buffer_len(§) != 0) { 707 buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY); 708 buffer_put_string(buf, buffer_ptr(§), 709 buffer_len(§)); 710 } 711 buffer_clear(§); 712 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { 713 debug3("%s: hash len %u ", __func__, rb->len); 714 buffer_put_string(§, rb->blob, rb->len); 715 } 716 if (buffer_len(§) != 0) { 717 buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1); 718 buffer_put_string(buf, buffer_ptr(§), 719 buffer_len(§)); 720 } 721 722 for (i = 0; i < nsign_keys; i++) { 723 if (key_to_blob(sign_keys[i], &kblob, &klen) == 0) 724 goto out; 725 726 debug3("%s: signature key len %u", __func__, klen); 727 buffer_put_char(buf, KRL_SECTION_SIGNATURE); 728 buffer_put_string(buf, kblob, klen); 729 730 if (key_sign(sign_keys[i], &sblob, &slen, 731 buffer_ptr(buf), buffer_len(buf)) == -1) 732 goto out; 733 debug3("%s: signature sig len %u", __func__, slen); 734 buffer_put_string(buf, sblob, slen); 735 } 736 737 r = 0; 738 out: 739 free(kblob); 740 free(sblob); 741 buffer_free(§); 742 return r; 743 } 744 745 static void 746 format_timestamp(u_int64_t timestamp, char *ts, size_t nts) 747 { 748 time_t t; 749 struct tm *tm; 750 751 t = timestamp; 752 tm = localtime(&t); 753 *ts = '\0'; 754 strftime(ts, nts, "%Y%m%dT%H%M%S", tm); 755 } 756 757 static int 758 parse_revoked_certs(Buffer *buf, struct ssh_krl *krl) 759 { 760 int ret = -1, nbits; 761 u_char type; 762 u_char *blob; 763 u_int blen; 764 Buffer subsect; 765 u_int64_t serial, serial_lo, serial_hi; 766 BIGNUM *bitmap = NULL; 767 char *key_id = NULL; 768 Key *ca_key = NULL; 769 770 buffer_init(&subsect); 771 772 if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL || 773 buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */ 774 error("%s: buffer error", __func__); 775 goto out; 776 } 777 if ((ca_key = key_from_blob(blob, blen)) == NULL) 778 goto out; 779 780 while (buffer_len(buf) > 0) { 781 if (buffer_get_char_ret(&type, buf) != 0 || 782 (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) { 783 error("%s: buffer error", __func__); 784 goto out; 785 } 786 buffer_clear(&subsect); 787 buffer_append(&subsect, blob, blen); 788 debug3("%s: subsection type 0x%02x", __func__, type); 789 /* buffer_dump(&subsect); */ 790 791 switch (type) { 792 case KRL_SECTION_CERT_SERIAL_LIST: 793 while (buffer_len(&subsect) > 0) { 794 if (buffer_get_int64_ret(&serial, 795 &subsect) != 0) { 796 error("%s: buffer error", __func__); 797 goto out; 798 } 799 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 800 serial) != 0) { 801 error("%s: update failed", __func__); 802 goto out; 803 } 804 } 805 break; 806 case KRL_SECTION_CERT_SERIAL_RANGE: 807 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 808 buffer_get_int64_ret(&serial_hi, &subsect) != 0) { 809 error("%s: buffer error", __func__); 810 goto out; 811 } 812 if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key, 813 serial_lo, serial_hi) != 0) { 814 error("%s: update failed", __func__); 815 goto out; 816 } 817 break; 818 case KRL_SECTION_CERT_SERIAL_BITMAP: 819 if ((bitmap = BN_new()) == NULL) { 820 error("%s: BN_new", __func__); 821 goto out; 822 } 823 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || 824 buffer_get_bignum2_ret(&subsect, bitmap) != 0) { 825 error("%s: buffer error", __func__); 826 goto out; 827 } 828 if ((nbits = BN_num_bits(bitmap)) < 0) { 829 error("%s: bitmap bits < 0", __func__); 830 goto out; 831 } 832 for (serial = 0; serial < (u_int)nbits; serial++) { 833 if (serial > 0 && serial_lo + serial == 0) { 834 error("%s: bitmap wraps u64", __func__); 835 goto out; 836 } 837 if (!BN_is_bit_set(bitmap, serial)) 838 continue; 839 if (ssh_krl_revoke_cert_by_serial(krl, ca_key, 840 serial_lo + serial) != 0) { 841 error("%s: update failed", __func__); 842 goto out; 843 } 844 } 845 BN_free(bitmap); 846 bitmap = NULL; 847 break; 848 case KRL_SECTION_CERT_KEY_ID: 849 while (buffer_len(&subsect) > 0) { 850 if ((key_id = buffer_get_cstring_ret(&subsect, 851 NULL)) == NULL) { 852 error("%s: buffer error", __func__); 853 goto out; 854 } 855 if (ssh_krl_revoke_cert_by_key_id(krl, ca_key, 856 key_id) != 0) { 857 error("%s: update failed", __func__); 858 goto out; 859 } 860 free(key_id); 861 key_id = NULL; 862 } 863 break; 864 default: 865 error("Unsupported KRL certificate section %u", type); 866 goto out; 867 } 868 if (buffer_len(&subsect) > 0) { 869 error("KRL certificate section contains unparsed data"); 870 goto out; 871 } 872 } 873 874 ret = 0; 875 out: 876 if (ca_key != NULL) 877 key_free(ca_key); 878 if (bitmap != NULL) 879 BN_free(bitmap); 880 free(key_id); 881 buffer_free(&subsect); 882 return ret; 883 } 884 885 886 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */ 887 int 888 ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp, 889 const Key **sign_ca_keys, u_int nsign_ca_keys) 890 { 891 Buffer copy, sect; 892 struct ssh_krl *krl; 893 char timestamp[64]; 894 int ret = -1, r, sig_seen; 895 Key *key = NULL, **ca_used = NULL; 896 u_char type, *blob, *rdata = NULL; 897 u_int i, j, sig_off, sects_off, rlen, blen, format_version, nca_used; 898 899 nca_used = 0; 900 *krlp = NULL; 901 if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 || 902 memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) { 903 debug3("%s: not a KRL", __func__); 904 /* 905 * Return success but a NULL *krlp here to signal that the 906 * file might be a simple list of keys. 907 */ 908 return 0; 909 } 910 911 /* Take a copy of the KRL buffer so we can verify its signature later */ 912 buffer_init(©); 913 buffer_append(©, buffer_ptr(buf), buffer_len(buf)); 914 915 buffer_init(§); 916 buffer_consume(©, sizeof(KRL_MAGIC) - 1); 917 918 if ((krl = ssh_krl_init()) == NULL) { 919 error("%s: alloc failed", __func__); 920 goto out; 921 } 922 923 if (buffer_get_int_ret(&format_version, ©) != 0) { 924 error("%s: KRL truncated", __func__); 925 goto out; 926 } 927 if (format_version != KRL_FORMAT_VERSION) { 928 error("%s: KRL unsupported format version %u", 929 __func__, format_version); 930 goto out; 931 } 932 if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 || 933 buffer_get_int64_ret(&krl->generated_date, ©) != 0 || 934 buffer_get_int64_ret(&krl->flags, ©) != 0 || 935 buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */ 936 (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) { 937 error("%s: buffer error", __func__); 938 goto out; 939 } 940 941 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); 942 debug("KRL version %llu generated at %s%s%s", 943 (long long unsigned)krl->krl_version, timestamp, 944 *krl->comment ? ": " : "", krl->comment); 945 946 /* 947 * 1st pass: verify signatures, if any. This is done to avoid 948 * detailed parsing of data whose provenance is unverified. 949 */ 950 sig_seen = 0; 951 sects_off = buffer_len(buf) - buffer_len(©); 952 while (buffer_len(©) > 0) { 953 if (buffer_get_char_ret(&type, ©) != 0 || 954 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 955 error("%s: buffer error", __func__); 956 goto out; 957 } 958 debug3("%s: first pass, section 0x%02x", __func__, type); 959 if (type != KRL_SECTION_SIGNATURE) { 960 if (sig_seen) { 961 error("KRL contains non-signature section " 962 "after signature"); 963 goto out; 964 } 965 /* Not interested for now. */ 966 continue; 967 } 968 sig_seen = 1; 969 /* First string component is the signing key */ 970 if ((key = key_from_blob(blob, blen)) == NULL) { 971 error("%s: invalid signature key", __func__); 972 goto out; 973 } 974 sig_off = buffer_len(buf) - buffer_len(©); 975 /* Second string component is the signature itself */ 976 if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 977 error("%s: buffer error", __func__); 978 goto out; 979 } 980 /* Check signature over entire KRL up to this point */ 981 if (key_verify(key, blob, blen, 982 buffer_ptr(buf), buffer_len(buf) - sig_off) != 1) { 983 error("bad signaure on KRL"); 984 goto out; 985 } 986 /* Check if this key has already signed this KRL */ 987 for (i = 0; i < nca_used; i++) { 988 if (key_equal(ca_used[i], key)) { 989 error("KRL signed more than once with " 990 "the same key"); 991 goto out; 992 } 993 } 994 /* Record keys used to sign the KRL */ 995 ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used)); 996 ca_used[nca_used++] = key; 997 key = NULL; 998 break; 999 } 1000 1001 /* 1002 * 2nd pass: parse and load the KRL, skipping the header to the point 1003 * where the section start. 1004 */ 1005 buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off, 1006 buffer_len(buf) - sects_off); 1007 while (buffer_len(©) > 0) { 1008 if (buffer_get_char_ret(&type, ©) != 0 || 1009 (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { 1010 error("%s: buffer error", __func__); 1011 goto out; 1012 } 1013 debug3("%s: second pass, section 0x%02x", __func__, type); 1014 buffer_clear(§); 1015 buffer_append(§, blob, blen); 1016 1017 switch (type) { 1018 case KRL_SECTION_CERTIFICATES: 1019 if ((r = parse_revoked_certs(§, krl)) != 0) 1020 goto out; 1021 break; 1022 case KRL_SECTION_EXPLICIT_KEY: 1023 case KRL_SECTION_FINGERPRINT_SHA1: 1024 while (buffer_len(§) > 0) { 1025 if ((rdata = buffer_get_string_ret(§, 1026 &rlen)) == NULL) { 1027 error("%s: buffer error", __func__); 1028 goto out; 1029 } 1030 if (type == KRL_SECTION_FINGERPRINT_SHA1 && 1031 rlen != 20) { 1032 error("%s: bad SHA1 length", __func__); 1033 goto out; 1034 } 1035 if (revoke_blob( 1036 type == KRL_SECTION_EXPLICIT_KEY ? 1037 &krl->revoked_keys : &krl->revoked_sha1s, 1038 rdata, rlen) != 0) 1039 goto out; 1040 rdata = NULL; /* revoke_blob frees blob */ 1041 } 1042 break; 1043 case KRL_SECTION_SIGNATURE: 1044 /* Handled above, but still need to stay in synch */ 1045 buffer_clear(§); 1046 if ((blob = buffer_get_string_ptr_ret(©, 1047 &blen)) == NULL) { 1048 error("%s: buffer error", __func__); 1049 goto out; 1050 } 1051 break; 1052 default: 1053 error("Unsupported KRL section %u", type); 1054 goto out; 1055 } 1056 if (buffer_len(§) > 0) { 1057 error("KRL section contains unparsed data"); 1058 goto out; 1059 } 1060 } 1061 1062 /* Check that the key(s) used to sign the KRL weren't revoked */ 1063 sig_seen = 0; 1064 for (i = 0; i < nca_used; i++) { 1065 if (ssh_krl_check_key(krl, ca_used[i]) == 0) 1066 sig_seen = 1; 1067 else { 1068 key_free(ca_used[i]); 1069 ca_used[i] = NULL; 1070 } 1071 } 1072 if (nca_used && !sig_seen) { 1073 error("All keys used to sign KRL were revoked"); 1074 goto out; 1075 } 1076 1077 /* If we have CA keys, then verify that one was used to sign the KRL */ 1078 if (sig_seen && nsign_ca_keys != 0) { 1079 sig_seen = 0; 1080 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) { 1081 for (j = 0; j < nca_used; j++) { 1082 if (ca_used[j] == NULL) 1083 continue; 1084 if (key_equal(ca_used[j], sign_ca_keys[i])) { 1085 sig_seen = 1; 1086 break; 1087 } 1088 } 1089 } 1090 if (!sig_seen) { 1091 error("KRL not signed with any trusted key"); 1092 goto out; 1093 } 1094 } 1095 1096 *krlp = krl; 1097 ret = 0; 1098 out: 1099 if (ret != 0) 1100 ssh_krl_free(krl); 1101 for (i = 0; i < nca_used; i++) { 1102 if (ca_used[i] != NULL) 1103 key_free(ca_used[i]); 1104 } 1105 free(ca_used); 1106 free(rdata); 1107 if (key != NULL) 1108 key_free(key); 1109 buffer_free(©); 1110 buffer_free(§); 1111 return ret; 1112 } 1113 1114 /* Checks whether a given key/cert is revoked. Does not check its CA */ 1115 static int 1116 is_key_revoked(struct ssh_krl *krl, const Key *key) 1117 { 1118 struct revoked_blob rb, *erb; 1119 struct revoked_serial rs, *ers; 1120 struct revoked_key_id rki, *erki; 1121 struct revoked_certs *rc; 1122 1123 /* Check explicitly revoked hashes first */ 1124 bzero(&rb, sizeof(rb)); 1125 if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL) 1126 return -1; 1127 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb); 1128 free(rb.blob); 1129 if (erb != NULL) { 1130 debug("%s: revoked by key SHA1", __func__); 1131 return -1; 1132 } 1133 1134 /* Next, explicit keys */ 1135 bzero(&rb, sizeof(rb)); 1136 if (plain_key_blob(key, &rb.blob, &rb.len) != 0) 1137 return -1; 1138 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb); 1139 free(rb.blob); 1140 if (erb != NULL) { 1141 debug("%s: revoked by explicit key", __func__); 1142 return -1; 1143 } 1144 1145 if (!key_is_cert(key)) 1146 return 0; 1147 1148 /* Check cert revocation */ 1149 if (revoked_certs_for_ca_key(krl, key->cert->signature_key, 1150 &rc, 0) != 0) 1151 return -1; 1152 if (rc == NULL) 1153 return 0; /* No entry for this CA */ 1154 1155 /* Check revocation by cert key ID */ 1156 bzero(&rki, sizeof(rki)); 1157 rki.key_id = key->cert->key_id; 1158 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki); 1159 if (erki != NULL) { 1160 debug("%s: revoked by key ID", __func__); 1161 return -1; 1162 } 1163 1164 /* 1165 * Legacy cert formats lack serial numbers. Zero serials numbers 1166 * are ignored (it's the default when the CA doesn't specify one). 1167 */ 1168 if (key_cert_is_legacy(key) || key->cert->serial == 0) 1169 return 0; 1170 1171 bzero(&rs, sizeof(rs)); 1172 rs.lo = rs.hi = key->cert->serial; 1173 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs); 1174 if (ers != NULL) { 1175 KRL_DBG(("%s: %"PRIu64" matched %"PRIu64":%"PRiu64, __func__, 1176 key->cert->serial, ers->lo, ers->hi)); 1177 debug("%s: revoked by serial", __func__); 1178 return -1; 1179 } 1180 KRL_DBG(("%s: %"PRIu64" no match", __func__, key->cert->serial)); 1181 1182 return 0; 1183 } 1184 1185 int 1186 ssh_krl_check_key(struct ssh_krl *krl, const Key *key) 1187 { 1188 int r; 1189 1190 debug2("%s: checking key", __func__); 1191 if ((r = is_key_revoked(krl, key)) != 0) 1192 return r; 1193 if (key_is_cert(key)) { 1194 debug2("%s: checking CA key", __func__); 1195 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0) 1196 return r; 1197 } 1198 debug3("%s: key okay", __func__); 1199 return 0; 1200 } 1201 1202 /* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */ 1203 int 1204 ssh_krl_file_contains_key(const char *path, const Key *key) 1205 { 1206 Buffer krlbuf; 1207 struct ssh_krl *krl; 1208 int revoked, fd; 1209 1210 if (path == NULL) 1211 return 0; 1212 1213 if ((fd = open(path, O_RDONLY)) == -1) { 1214 error("open %s: %s", path, strerror(errno)); 1215 error("Revoked keys file not accessible - refusing public key " 1216 "authentication"); 1217 return -1; 1218 } 1219 buffer_init(&krlbuf); 1220 if (!key_load_file(fd, path, &krlbuf)) { 1221 close(fd); 1222 buffer_free(&krlbuf); 1223 error("Revoked keys file not readable - refusing public key " 1224 "authentication"); 1225 return -1; 1226 } 1227 close(fd); 1228 if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) { 1229 buffer_free(&krlbuf); 1230 error("Invalid KRL, refusing public key " 1231 "authentication"); 1232 return -1; 1233 } 1234 buffer_free(&krlbuf); 1235 if (krl == NULL) { 1236 debug3("%s: %s is not a KRL file", __func__, path); 1237 return -2; 1238 } 1239 debug2("%s: checking KRL %s", __func__, path); 1240 revoked = ssh_krl_check_key(krl, key) != 0; 1241 ssh_krl_free(krl); 1242 return revoked ? -1 : 0; 1243 } 1244