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root/src/vendor-crypto/openssh/6.6p1/krl.c
Revision: 6864
Committed: Sat Oct 11 16:33:42 2014 UTC (9 years, 6 months ago) by laffer1
Content type: text/plain
File size: 33108 byte(s)
Log Message: 
tag openssh 6.6p1

File Contents

# Content
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 1.14 2014/01/31 16:39:19 tedu 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 == 0 ? -1 : 0;
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(&sect);
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(&sect, 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(&sect), buffer_len(&sect));
578 }
579
580 /* If we are starting a new section then prepare it now */
581 if (next_state != state || force_new_sect) {
582 debug3("%s: start state 0x%02x", __func__, next_state);
583 state = next_state;
584 buffer_clear(&sect);
585 switch (state) {
586 case KRL_SECTION_CERT_SERIAL_LIST:
587 case KRL_SECTION_CERT_SERIAL_RANGE:
588 break;
589 case KRL_SECTION_CERT_SERIAL_BITMAP:
590 if ((bitmap = BN_new()) == NULL)
591 goto out;
592 bitmap_start = rs->lo;
593 buffer_put_int64(&sect, bitmap_start);
594 break;
595 }
596 }
597
598 /* Perform section-specific processing */
599 switch (state) {
600 case KRL_SECTION_CERT_SERIAL_LIST:
601 for (i = 0; i < contig; i++)
602 buffer_put_int64(&sect, rs->lo + i);
603 break;
604 case KRL_SECTION_CERT_SERIAL_RANGE:
605 buffer_put_int64(&sect, rs->lo);
606 buffer_put_int64(&sect, rs->hi);
607 break;
608 case KRL_SECTION_CERT_SERIAL_BITMAP:
609 if (rs->lo - bitmap_start > INT_MAX) {
610 error("%s: insane bitmap gap", __func__);
611 goto out;
612 }
613 for (i = 0; i < contig; i++) {
614 if (BN_set_bit(bitmap,
615 rs->lo + i - bitmap_start) != 1)
616 goto out;
617 }
618 break;
619 }
620 last = rs->hi;
621 }
622 /* Flush the remaining section, if any */
623 if (state != 0) {
624 debug3("%s: serial final flush for state 0x%02x",
625 __func__, state);
626 switch (state) {
627 case KRL_SECTION_CERT_SERIAL_LIST:
628 case KRL_SECTION_CERT_SERIAL_RANGE:
629 break;
630 case KRL_SECTION_CERT_SERIAL_BITMAP:
631 buffer_put_bignum2(&sect, bitmap);
632 BN_free(bitmap);
633 bitmap = NULL;
634 break;
635 }
636 buffer_put_char(buf, state);
637 buffer_put_string(buf,
638 buffer_ptr(&sect), buffer_len(&sect));
639 }
640 debug3("%s: serial done ", __func__);
641
642 /* Now output a section for any revocations by key ID */
643 buffer_clear(&sect);
644 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
645 debug3("%s: key ID %s", __func__, rki->key_id);
646 buffer_put_cstring(&sect, rki->key_id);
647 }
648 if (buffer_len(&sect) != 0) {
649 buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID);
650 buffer_put_string(buf, buffer_ptr(&sect),
651 buffer_len(&sect));
652 }
653 r = 0;
654 out:
655 if (bitmap != NULL)
656 BN_free(bitmap);
657 buffer_free(&sect);
658 return r;
659 }
660
661 int
662 ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys,
663 u_int nsign_keys)
664 {
665 int r = -1;
666 struct revoked_certs *rc;
667 struct revoked_blob *rb;
668 Buffer sect;
669 u_char *kblob = NULL, *sblob = NULL;
670 u_int klen, slen, i;
671
672 if (krl->generated_date == 0)
673 krl->generated_date = time(NULL);
674
675 buffer_init(&sect);
676
677 /* Store the header */
678 buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1);
679 buffer_put_int(buf, KRL_FORMAT_VERSION);
680 buffer_put_int64(buf, krl->krl_version);
681 buffer_put_int64(buf, krl->generated_date);
682 buffer_put_int64(buf, krl->flags);
683 buffer_put_string(buf, NULL, 0);
684 buffer_put_cstring(buf, krl->comment ? krl->comment : "");
685
686 /* Store sections for revoked certificates */
687 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
688 if (revoked_certs_generate(rc, &sect) != 0)
689 goto out;
690 buffer_put_char(buf, KRL_SECTION_CERTIFICATES);
691 buffer_put_string(buf, buffer_ptr(&sect),
692 buffer_len(&sect));
693 }
694
695 /* Finally, output sections for revocations by public key/hash */
696 buffer_clear(&sect);
697 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
698 debug3("%s: key len %u ", __func__, rb->len);
699 buffer_put_string(&sect, rb->blob, rb->len);
700 }
701 if (buffer_len(&sect) != 0) {
702 buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY);
703 buffer_put_string(buf, buffer_ptr(&sect),
704 buffer_len(&sect));
705 }
706 buffer_clear(&sect);
707 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
708 debug3("%s: hash len %u ", __func__, rb->len);
709 buffer_put_string(&sect, rb->blob, rb->len);
710 }
711 if (buffer_len(&sect) != 0) {
712 buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1);
713 buffer_put_string(buf, buffer_ptr(&sect),
714 buffer_len(&sect));
715 }
716
717 for (i = 0; i < nsign_keys; i++) {
718 if (key_to_blob(sign_keys[i], &kblob, &klen) == 0)
719 goto out;
720
721 debug3("%s: signature key len %u", __func__, klen);
722 buffer_put_char(buf, KRL_SECTION_SIGNATURE);
723 buffer_put_string(buf, kblob, klen);
724
725 if (key_sign(sign_keys[i], &sblob, &slen,
726 buffer_ptr(buf), buffer_len(buf)) == -1)
727 goto out;
728 debug3("%s: signature sig len %u", __func__, slen);
729 buffer_put_string(buf, sblob, slen);
730 }
731
732 r = 0;
733 out:
734 free(kblob);
735 free(sblob);
736 buffer_free(&sect);
737 return r;
738 }
739
740 static void
741 format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
742 {
743 time_t t;
744 struct tm *tm;
745
746 t = timestamp;
747 tm = localtime(&t);
748 *ts = '\0';
749 strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
750 }
751
752 static int
753 parse_revoked_certs(Buffer *buf, struct ssh_krl *krl)
754 {
755 int ret = -1, nbits;
756 u_char type, *blob;
757 u_int blen;
758 Buffer subsect;
759 u_int64_t serial, serial_lo, serial_hi;
760 BIGNUM *bitmap = NULL;
761 char *key_id = NULL;
762 Key *ca_key = NULL;
763
764 buffer_init(&subsect);
765
766 if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL ||
767 buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */
768 error("%s: buffer error", __func__);
769 goto out;
770 }
771 if ((ca_key = key_from_blob(blob, blen)) == NULL)
772 goto out;
773
774 while (buffer_len(buf) > 0) {
775 if (buffer_get_char_ret(&type, buf) != 0 ||
776 (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) {
777 error("%s: buffer error", __func__);
778 goto out;
779 }
780 buffer_clear(&subsect);
781 buffer_append(&subsect, blob, blen);
782 debug3("%s: subsection type 0x%02x", __func__, type);
783 /* buffer_dump(&subsect); */
784
785 switch (type) {
786 case KRL_SECTION_CERT_SERIAL_LIST:
787 while (buffer_len(&subsect) > 0) {
788 if (buffer_get_int64_ret(&serial,
789 &subsect) != 0) {
790 error("%s: buffer error", __func__);
791 goto out;
792 }
793 if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
794 serial) != 0) {
795 error("%s: update failed", __func__);
796 goto out;
797 }
798 }
799 break;
800 case KRL_SECTION_CERT_SERIAL_RANGE:
801 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
802 buffer_get_int64_ret(&serial_hi, &subsect) != 0) {
803 error("%s: buffer error", __func__);
804 goto out;
805 }
806 if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key,
807 serial_lo, serial_hi) != 0) {
808 error("%s: update failed", __func__);
809 goto out;
810 }
811 break;
812 case KRL_SECTION_CERT_SERIAL_BITMAP:
813 if ((bitmap = BN_new()) == NULL) {
814 error("%s: BN_new", __func__);
815 goto out;
816 }
817 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
818 buffer_get_bignum2_ret(&subsect, bitmap) != 0) {
819 error("%s: buffer error", __func__);
820 goto out;
821 }
822 if ((nbits = BN_num_bits(bitmap)) < 0) {
823 error("%s: bitmap bits < 0", __func__);
824 goto out;
825 }
826 for (serial = 0; serial < (u_int)nbits; serial++) {
827 if (serial > 0 && serial_lo + serial == 0) {
828 error("%s: bitmap wraps u64", __func__);
829 goto out;
830 }
831 if (!BN_is_bit_set(bitmap, serial))
832 continue;
833 if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
834 serial_lo + serial) != 0) {
835 error("%s: update failed", __func__);
836 goto out;
837 }
838 }
839 BN_free(bitmap);
840 bitmap = NULL;
841 break;
842 case KRL_SECTION_CERT_KEY_ID:
843 while (buffer_len(&subsect) > 0) {
844 if ((key_id = buffer_get_cstring_ret(&subsect,
845 NULL)) == NULL) {
846 error("%s: buffer error", __func__);
847 goto out;
848 }
849 if (ssh_krl_revoke_cert_by_key_id(krl, ca_key,
850 key_id) != 0) {
851 error("%s: update failed", __func__);
852 goto out;
853 }
854 free(key_id);
855 key_id = NULL;
856 }
857 break;
858 default:
859 error("Unsupported KRL certificate section %u", type);
860 goto out;
861 }
862 if (buffer_len(&subsect) > 0) {
863 error("KRL certificate section contains unparsed data");
864 goto out;
865 }
866 }
867
868 ret = 0;
869 out:
870 if (ca_key != NULL)
871 key_free(ca_key);
872 if (bitmap != NULL)
873 BN_free(bitmap);
874 free(key_id);
875 buffer_free(&subsect);
876 return ret;
877 }
878
879
880 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
881 int
882 ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp,
883 const Key **sign_ca_keys, u_int nsign_ca_keys)
884 {
885 Buffer copy, sect;
886 struct ssh_krl *krl;
887 char timestamp[64];
888 int ret = -1, r, sig_seen;
889 Key *key = NULL, **ca_used = NULL;
890 u_char type, *blob, *rdata = NULL;
891 u_int i, j, sig_off, sects_off, rlen, blen, format_version, nca_used;
892
893 nca_used = 0;
894 *krlp = NULL;
895 if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 ||
896 memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
897 debug3("%s: not a KRL", __func__);
898 /*
899 * Return success but a NULL *krlp here to signal that the
900 * file might be a simple list of keys.
901 */
902 return 0;
903 }
904
905 /* Take a copy of the KRL buffer so we can verify its signature later */
906 buffer_init(&copy);
907 buffer_append(&copy, buffer_ptr(buf), buffer_len(buf));
908
909 buffer_init(&sect);
910 buffer_consume(&copy, sizeof(KRL_MAGIC) - 1);
911
912 if ((krl = ssh_krl_init()) == NULL) {
913 error("%s: alloc failed", __func__);
914 goto out;
915 }
916
917 if (buffer_get_int_ret(&format_version, &copy) != 0) {
918 error("%s: KRL truncated", __func__);
919 goto out;
920 }
921 if (format_version != KRL_FORMAT_VERSION) {
922 error("%s: KRL unsupported format version %u",
923 __func__, format_version);
924 goto out;
925 }
926 if (buffer_get_int64_ret(&krl->krl_version, &copy) != 0 ||
927 buffer_get_int64_ret(&krl->generated_date, &copy) != 0 ||
928 buffer_get_int64_ret(&krl->flags, &copy) != 0 ||
929 buffer_get_string_ptr_ret(&copy, NULL) == NULL || /* reserved */
930 (krl->comment = buffer_get_cstring_ret(&copy, NULL)) == NULL) {
931 error("%s: buffer error", __func__);
932 goto out;
933 }
934
935 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
936 debug("KRL version %llu generated at %s%s%s",
937 (long long unsigned)krl->krl_version, timestamp,
938 *krl->comment ? ": " : "", krl->comment);
939
940 /*
941 * 1st pass: verify signatures, if any. This is done to avoid
942 * detailed parsing of data whose provenance is unverified.
943 */
944 sig_seen = 0;
945 sects_off = buffer_len(buf) - buffer_len(&copy);
946 while (buffer_len(&copy) > 0) {
947 if (buffer_get_char_ret(&type, &copy) != 0 ||
948 (blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
949 error("%s: buffer error", __func__);
950 goto out;
951 }
952 debug3("%s: first pass, section 0x%02x", __func__, type);
953 if (type != KRL_SECTION_SIGNATURE) {
954 if (sig_seen) {
955 error("KRL contains non-signature section "
956 "after signature");
957 goto out;
958 }
959 /* Not interested for now. */
960 continue;
961 }
962 sig_seen = 1;
963 /* First string component is the signing key */
964 if ((key = key_from_blob(blob, blen)) == NULL) {
965 error("%s: invalid signature key", __func__);
966 goto out;
967 }
968 sig_off = buffer_len(buf) - buffer_len(&copy);
969 /* Second string component is the signature itself */
970 if ((blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
971 error("%s: buffer error", __func__);
972 goto out;
973 }
974 /* Check signature over entire KRL up to this point */
975 if (key_verify(key, blob, blen,
976 buffer_ptr(buf), buffer_len(buf) - sig_off) != 1) {
977 error("bad signaure on KRL");
978 goto out;
979 }
980 /* Check if this key has already signed this KRL */
981 for (i = 0; i < nca_used; i++) {
982 if (key_equal(ca_used[i], key)) {
983 error("KRL signed more than once with "
984 "the same key");
985 goto out;
986 }
987 }
988 /* Record keys used to sign the KRL */
989 ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used));
990 ca_used[nca_used++] = key;
991 key = NULL;
992 break;
993 }
994
995 /*
996 * 2nd pass: parse and load the KRL, skipping the header to the point
997 * where the section start.
998 */
999 buffer_append(&copy, (u_char*)buffer_ptr(buf) + sects_off,
1000 buffer_len(buf) - sects_off);
1001 while (buffer_len(&copy) > 0) {
1002 if (buffer_get_char_ret(&type, &copy) != 0 ||
1003 (blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
1004 error("%s: buffer error", __func__);
1005 goto out;
1006 }
1007 debug3("%s: second pass, section 0x%02x", __func__, type);
1008 buffer_clear(&sect);
1009 buffer_append(&sect, blob, blen);
1010
1011 switch (type) {
1012 case KRL_SECTION_CERTIFICATES:
1013 if ((r = parse_revoked_certs(&sect, krl)) != 0)
1014 goto out;
1015 break;
1016 case KRL_SECTION_EXPLICIT_KEY:
1017 case KRL_SECTION_FINGERPRINT_SHA1:
1018 while (buffer_len(&sect) > 0) {
1019 if ((rdata = buffer_get_string_ret(&sect,
1020 &rlen)) == NULL) {
1021 error("%s: buffer error", __func__);
1022 goto out;
1023 }
1024 if (type == KRL_SECTION_FINGERPRINT_SHA1 &&
1025 rlen != 20) {
1026 error("%s: bad SHA1 length", __func__);
1027 goto out;
1028 }
1029 if (revoke_blob(
1030 type == KRL_SECTION_EXPLICIT_KEY ?
1031 &krl->revoked_keys : &krl->revoked_sha1s,
1032 rdata, rlen) != 0)
1033 goto out;
1034 rdata = NULL; /* revoke_blob frees blob */
1035 }
1036 break;
1037 case KRL_SECTION_SIGNATURE:
1038 /* Handled above, but still need to stay in synch */
1039 buffer_clear(&sect);
1040 if ((blob = buffer_get_string_ptr_ret(&copy,
1041 &blen)) == NULL) {
1042 error("%s: buffer error", __func__);
1043 goto out;
1044 }
1045 break;
1046 default:
1047 error("Unsupported KRL section %u", type);
1048 goto out;
1049 }
1050 if (buffer_len(&sect) > 0) {
1051 error("KRL section contains unparsed data");
1052 goto out;
1053 }
1054 }
1055
1056 /* Check that the key(s) used to sign the KRL weren't revoked */
1057 sig_seen = 0;
1058 for (i = 0; i < nca_used; i++) {
1059 if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1060 sig_seen = 1;
1061 else {
1062 key_free(ca_used[i]);
1063 ca_used[i] = NULL;
1064 }
1065 }
1066 if (nca_used && !sig_seen) {
1067 error("All keys used to sign KRL were revoked");
1068 goto out;
1069 }
1070
1071 /* If we have CA keys, then verify that one was used to sign the KRL */
1072 if (sig_seen && nsign_ca_keys != 0) {
1073 sig_seen = 0;
1074 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1075 for (j = 0; j < nca_used; j++) {
1076 if (ca_used[j] == NULL)
1077 continue;
1078 if (key_equal(ca_used[j], sign_ca_keys[i])) {
1079 sig_seen = 1;
1080 break;
1081 }
1082 }
1083 }
1084 if (!sig_seen) {
1085 error("KRL not signed with any trusted key");
1086 goto out;
1087 }
1088 }
1089
1090 *krlp = krl;
1091 ret = 0;
1092 out:
1093 if (ret != 0)
1094 ssh_krl_free(krl);
1095 for (i = 0; i < nca_used; i++) {
1096 if (ca_used[i] != NULL)
1097 key_free(ca_used[i]);
1098 }
1099 free(ca_used);
1100 free(rdata);
1101 if (key != NULL)
1102 key_free(key);
1103 buffer_free(&copy);
1104 buffer_free(&sect);
1105 return ret;
1106 }
1107
1108 /* Checks whether a given key/cert is revoked. Does not check its CA */
1109 static int
1110 is_key_revoked(struct ssh_krl *krl, const Key *key)
1111 {
1112 struct revoked_blob rb, *erb;
1113 struct revoked_serial rs, *ers;
1114 struct revoked_key_id rki, *erki;
1115 struct revoked_certs *rc;
1116
1117 /* Check explicitly revoked hashes first */
1118 memset(&rb, 0, sizeof(rb));
1119 if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL)
1120 return -1;
1121 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1122 free(rb.blob);
1123 if (erb != NULL) {
1124 debug("%s: revoked by key SHA1", __func__);
1125 return -1;
1126 }
1127
1128 /* Next, explicit keys */
1129 memset(&rb, 0, sizeof(rb));
1130 if (plain_key_blob(key, &rb.blob, &rb.len) != 0)
1131 return -1;
1132 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1133 free(rb.blob);
1134 if (erb != NULL) {
1135 debug("%s: revoked by explicit key", __func__);
1136 return -1;
1137 }
1138
1139 if (!key_is_cert(key))
1140 return 0;
1141
1142 /* Check cert revocation */
1143 if (revoked_certs_for_ca_key(krl, key->cert->signature_key,
1144 &rc, 0) != 0)
1145 return -1;
1146 if (rc == NULL)
1147 return 0; /* No entry for this CA */
1148
1149 /* Check revocation by cert key ID */
1150 memset(&rki, 0, sizeof(rki));
1151 rki.key_id = key->cert->key_id;
1152 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1153 if (erki != NULL) {
1154 debug("%s: revoked by key ID", __func__);
1155 return -1;
1156 }
1157
1158 /*
1159 * Legacy cert formats lack serial numbers. Zero serials numbers
1160 * are ignored (it's the default when the CA doesn't specify one).
1161 */
1162 if (key_cert_is_legacy(key) || key->cert->serial == 0)
1163 return 0;
1164
1165 memset(&rs, 0, sizeof(rs));
1166 rs.lo = rs.hi = key->cert->serial;
1167 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1168 if (ers != NULL) {
1169 KRL_DBG(("%s: %llu matched %llu:%llu", __func__,
1170 key->cert->serial, ers->lo, ers->hi));
1171 debug("%s: revoked by serial", __func__);
1172 return -1;
1173 }
1174 KRL_DBG(("%s: %llu no match", __func__, key->cert->serial));
1175
1176 return 0;
1177 }
1178
1179 int
1180 ssh_krl_check_key(struct ssh_krl *krl, const Key *key)
1181 {
1182 int r;
1183
1184 debug2("%s: checking key", __func__);
1185 if ((r = is_key_revoked(krl, key)) != 0)
1186 return r;
1187 if (key_is_cert(key)) {
1188 debug2("%s: checking CA key", __func__);
1189 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1190 return r;
1191 }
1192 debug3("%s: key okay", __func__);
1193 return 0;
1194 }
1195
1196 /* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */
1197 int
1198 ssh_krl_file_contains_key(const char *path, const Key *key)
1199 {
1200 Buffer krlbuf;
1201 struct ssh_krl *krl;
1202 int revoked, fd;
1203
1204 if (path == NULL)
1205 return 0;
1206
1207 if ((fd = open(path, O_RDONLY)) == -1) {
1208 error("open %s: %s", path, strerror(errno));
1209 error("Revoked keys file not accessible - refusing public key "
1210 "authentication");
1211 return -1;
1212 }
1213 buffer_init(&krlbuf);
1214 if (!key_load_file(fd, path, &krlbuf)) {
1215 close(fd);
1216 buffer_free(&krlbuf);
1217 error("Revoked keys file not readable - refusing public key "
1218 "authentication");
1219 return -1;
1220 }
1221 close(fd);
1222 if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) {
1223 buffer_free(&krlbuf);
1224 error("Invalid KRL, refusing public key "
1225 "authentication");
1226 return -1;
1227 }
1228 buffer_free(&krlbuf);
1229 if (krl == NULL) {
1230 debug3("%s: %s is not a KRL file", __func__, path);
1231 return -2;
1232 }
1233 debug2("%s: checking KRL %s", __func__, path);
1234 revoked = ssh_krl_check_key(krl, key) != 0;
1235 ssh_krl_free(krl);
1236 return revoked ? -1 : 0;
1237 }