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 1.50 2020/04/03 05:48:57 djm Exp $ */
18
19 #include "includes.h"
20
21 #include <sys/types.h>
22 #include <openbsd-compat/sys-tree.h>
23 #include <openbsd-compat/sys-queue.h>
24
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <limits.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <time.h>
31 #include <unistd.h>
32
33 #include "sshbuf.h"
34 #include "ssherr.h"
35 #include "sshkey.h"
36 #include "authfile.h"
37 #include "misc.h"
38 #include "log.h"
39 #include "digest.h"
40 #include "bitmap.h"
41 #include "utf8.h"
42
43 #include "krl.h"
44
45 /* #define DEBUG_KRL */
46 #ifdef DEBUG_KRL
47 # define KRL_DBG(x) debug3 x
48 #else
49 # define KRL_DBG(x)
50 #endif
51
52 /*
53 * Trees of revoked serial numbers, key IDs and keys. This allows
54 * quick searching, querying and producing lists in canonical order.
55 */
56
57 /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */
58 struct revoked_serial {
59 u_int64_t lo, hi;
60 RB_ENTRY(revoked_serial) tree_entry;
61 };
62 static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b);
63 RB_HEAD(revoked_serial_tree, revoked_serial);
64 RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp);
65
66 /* Tree of key IDs */
67 struct revoked_key_id {
68 char *key_id;
69 RB_ENTRY(revoked_key_id) tree_entry;
70 };
71 static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b);
72 RB_HEAD(revoked_key_id_tree, revoked_key_id);
73 RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp);
74
75 /* Tree of blobs (used for keys and fingerprints) */
76 struct revoked_blob {
77 u_char *blob;
78 size_t len;
79 RB_ENTRY(revoked_blob) tree_entry;
80 };
81 static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b);
82 RB_HEAD(revoked_blob_tree, revoked_blob);
83 RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp);
84
85 /* Tracks revoked certs for a single CA */
86 struct revoked_certs {
87 struct sshkey *ca_key;
88 struct revoked_serial_tree revoked_serials;
89 struct revoked_key_id_tree revoked_key_ids;
90 TAILQ_ENTRY(revoked_certs) entry;
91 };
92 TAILQ_HEAD(revoked_certs_list, revoked_certs);
93
94 struct ssh_krl {
95 u_int64_t krl_version;
96 u_int64_t generated_date;
97 u_int64_t flags;
98 char *comment;
99 struct revoked_blob_tree revoked_keys;
100 struct revoked_blob_tree revoked_sha1s;
101 struct revoked_blob_tree revoked_sha256s;
102 struct revoked_certs_list revoked_certs;
103 };
104
105 /* Return equal if a and b overlap */
106 static int
serial_cmp(struct revoked_serial * a,struct revoked_serial * b)107 serial_cmp(struct revoked_serial *a, struct revoked_serial *b)
108 {
109 if (a->hi >= b->lo && a->lo <= b->hi)
110 return 0;
111 return a->lo < b->lo ? -1 : 1;
112 }
113
114 static int
key_id_cmp(struct revoked_key_id * a,struct revoked_key_id * b)115 key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b)
116 {
117 return strcmp(a->key_id, b->key_id);
118 }
119
120 static int
blob_cmp(struct revoked_blob * a,struct revoked_blob * b)121 blob_cmp(struct revoked_blob *a, struct revoked_blob *b)
122 {
123 int r;
124
125 if (a->len != b->len) {
126 if ((r = memcmp(a->blob, b->blob, MINIMUM(a->len, b->len))) != 0)
127 return r;
128 return a->len > b->len ? 1 : -1;
129 } else
130 return memcmp(a->blob, b->blob, a->len);
131 }
132
133 struct ssh_krl *
ssh_krl_init(void)134 ssh_krl_init(void)
135 {
136 struct ssh_krl *krl;
137
138 if ((krl = calloc(1, sizeof(*krl))) == NULL)
139 return NULL;
140 RB_INIT(&krl->revoked_keys);
141 RB_INIT(&krl->revoked_sha1s);
142 RB_INIT(&krl->revoked_sha256s);
143 TAILQ_INIT(&krl->revoked_certs);
144 return krl;
145 }
146
147 static void
revoked_certs_free(struct revoked_certs * rc)148 revoked_certs_free(struct revoked_certs *rc)
149 {
150 struct revoked_serial *rs, *trs;
151 struct revoked_key_id *rki, *trki;
152
153 RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) {
154 RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs);
155 free(rs);
156 }
157 RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) {
158 RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki);
159 free(rki->key_id);
160 free(rki);
161 }
162 sshkey_free(rc->ca_key);
163 }
164
165 void
ssh_krl_free(struct ssh_krl * krl)166 ssh_krl_free(struct ssh_krl *krl)
167 {
168 struct revoked_blob *rb, *trb;
169 struct revoked_certs *rc, *trc;
170
171 if (krl == NULL)
172 return;
173
174 free(krl->comment);
175 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) {
176 RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb);
177 free(rb->blob);
178 free(rb);
179 }
180 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) {
181 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb);
182 free(rb->blob);
183 free(rb);
184 }
185 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha256s, trb) {
186 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha256s, rb);
187 free(rb->blob);
188 free(rb);
189 }
190 TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) {
191 TAILQ_REMOVE(&krl->revoked_certs, rc, entry);
192 revoked_certs_free(rc);
193 }
194 }
195
196 void
ssh_krl_set_version(struct ssh_krl * krl,u_int64_t version)197 ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version)
198 {
199 krl->krl_version = version;
200 }
201
202 int
ssh_krl_set_comment(struct ssh_krl * krl,const char * comment)203 ssh_krl_set_comment(struct ssh_krl *krl, const char *comment)
204 {
205 free(krl->comment);
206 if ((krl->comment = strdup(comment)) == NULL)
207 return SSH_ERR_ALLOC_FAIL;
208 return 0;
209 }
210
211 /*
212 * Find the revoked_certs struct for a CA key. If allow_create is set then
213 * create a new one in the tree if one did not exist already.
214 */
215 static int
revoked_certs_for_ca_key(struct ssh_krl * krl,const struct sshkey * ca_key,struct revoked_certs ** rcp,int allow_create)216 revoked_certs_for_ca_key(struct ssh_krl *krl, const struct sshkey *ca_key,
217 struct revoked_certs **rcp, int allow_create)
218 {
219 struct revoked_certs *rc;
220 int r;
221
222 *rcp = NULL;
223 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
224 if ((ca_key == NULL && rc->ca_key == NULL) ||
225 sshkey_equal(rc->ca_key, ca_key)) {
226 *rcp = rc;
227 return 0;
228 }
229 }
230 if (!allow_create)
231 return 0;
232 /* If this CA doesn't exist in the list then add it now */
233 if ((rc = calloc(1, sizeof(*rc))) == NULL)
234 return SSH_ERR_ALLOC_FAIL;
235 if (ca_key == NULL)
236 rc->ca_key = NULL;
237 else if ((r = sshkey_from_private(ca_key, &rc->ca_key)) != 0) {
238 free(rc);
239 return r;
240 }
241 RB_INIT(&rc->revoked_serials);
242 RB_INIT(&rc->revoked_key_ids);
243 TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry);
244 KRL_DBG(("%s: new CA %s", __func__,
245 ca_key == NULL ? "*" : sshkey_type(ca_key)));
246 *rcp = rc;
247 return 0;
248 }
249
250 static int
insert_serial_range(struct revoked_serial_tree * rt,u_int64_t lo,u_int64_t hi)251 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi)
252 {
253 struct revoked_serial rs, *ers, *crs, *irs;
254
255 KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi));
256 memset(&rs, 0, sizeof(rs));
257 rs.lo = lo;
258 rs.hi = hi;
259 ers = RB_NFIND(revoked_serial_tree, rt, &rs);
260 if (ers == NULL || serial_cmp(ers, &rs) != 0) {
261 /* No entry matches. Just insert */
262 if ((irs = malloc(sizeof(rs))) == NULL)
263 return SSH_ERR_ALLOC_FAIL;
264 memcpy(irs, &rs, sizeof(*irs));
265 ers = RB_INSERT(revoked_serial_tree, rt, irs);
266 if (ers != NULL) {
267 KRL_DBG(("%s: bad: ers != NULL", __func__));
268 /* Shouldn't happen */
269 free(irs);
270 return SSH_ERR_INTERNAL_ERROR;
271 }
272 ers = irs;
273 } else {
274 KRL_DBG(("%s: overlap found %llu:%llu", __func__,
275 ers->lo, ers->hi));
276 /*
277 * The inserted entry overlaps an existing one. Grow the
278 * existing entry.
279 */
280 if (ers->lo > lo)
281 ers->lo = lo;
282 if (ers->hi < hi)
283 ers->hi = hi;
284 }
285
286 /*
287 * The inserted or revised range might overlap or abut adjacent ones;
288 * coalesce as necessary.
289 */
290
291 /* Check predecessors */
292 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) {
293 KRL_DBG(("%s: pred %llu:%llu", __func__, crs->lo, crs->hi));
294 if (ers->lo != 0 && crs->hi < ers->lo - 1)
295 break;
296 /* This entry overlaps. */
297 if (crs->lo < ers->lo) {
298 ers->lo = crs->lo;
299 KRL_DBG(("%s: pred extend %llu:%llu", __func__,
300 ers->lo, ers->hi));
301 }
302 RB_REMOVE(revoked_serial_tree, rt, crs);
303 free(crs);
304 }
305 /* Check successors */
306 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) {
307 KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi));
308 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1)
309 break;
310 /* This entry overlaps. */
311 if (crs->hi > ers->hi) {
312 ers->hi = crs->hi;
313 KRL_DBG(("%s: succ extend %llu:%llu", __func__,
314 ers->lo, ers->hi));
315 }
316 RB_REMOVE(revoked_serial_tree, rt, crs);
317 free(crs);
318 }
319 KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi));
320 return 0;
321 }
322
323 int
ssh_krl_revoke_cert_by_serial(struct ssh_krl * krl,const struct sshkey * ca_key,u_int64_t serial)324 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const struct sshkey *ca_key,
325 u_int64_t serial)
326 {
327 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial);
328 }
329
330 int
ssh_krl_revoke_cert_by_serial_range(struct ssh_krl * krl,const struct sshkey * ca_key,u_int64_t lo,u_int64_t hi)331 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl,
332 const struct sshkey *ca_key, u_int64_t lo, u_int64_t hi)
333 {
334 struct revoked_certs *rc;
335 int r;
336
337 if (lo > hi || lo == 0)
338 return SSH_ERR_INVALID_ARGUMENT;
339 if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
340 return r;
341 return insert_serial_range(&rc->revoked_serials, lo, hi);
342 }
343
344 int
ssh_krl_revoke_cert_by_key_id(struct ssh_krl * krl,const struct sshkey * ca_key,const char * key_id)345 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const struct sshkey *ca_key,
346 const char *key_id)
347 {
348 struct revoked_key_id *rki, *erki;
349 struct revoked_certs *rc;
350 int r;
351
352 if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
353 return r;
354
355 KRL_DBG(("%s: revoke %s", __func__, key_id));
356 if ((rki = calloc(1, sizeof(*rki))) == NULL ||
357 (rki->key_id = strdup(key_id)) == NULL) {
358 free(rki);
359 return SSH_ERR_ALLOC_FAIL;
360 }
361 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki);
362 if (erki != NULL) {
363 free(rki->key_id);
364 free(rki);
365 }
366 return 0;
367 }
368
369 /* Convert "key" to a public key blob without any certificate information */
370 static int
plain_key_blob(const struct sshkey * key,u_char ** blob,size_t * blen)371 plain_key_blob(const struct sshkey *key, u_char **blob, size_t *blen)
372 {
373 struct sshkey *kcopy;
374 int r;
375
376 if ((r = sshkey_from_private(key, &kcopy)) != 0)
377 return r;
378 if (sshkey_is_cert(kcopy)) {
379 if ((r = sshkey_drop_cert(kcopy)) != 0) {
380 sshkey_free(kcopy);
381 return r;
382 }
383 }
384 r = sshkey_to_blob(kcopy, blob, blen);
385 sshkey_free(kcopy);
386 return r;
387 }
388
389 /* Revoke a key blob. Ownership of blob is transferred to the tree */
390 static int
revoke_blob(struct revoked_blob_tree * rbt,u_char * blob,size_t len)391 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, size_t len)
392 {
393 struct revoked_blob *rb, *erb;
394
395 if ((rb = calloc(1, sizeof(*rb))) == NULL)
396 return SSH_ERR_ALLOC_FAIL;
397 rb->blob = blob;
398 rb->len = len;
399 erb = RB_INSERT(revoked_blob_tree, rbt, rb);
400 if (erb != NULL) {
401 free(rb->blob);
402 free(rb);
403 }
404 return 0;
405 }
406
407 int
ssh_krl_revoke_key_explicit(struct ssh_krl * krl,const struct sshkey * key)408 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const struct sshkey *key)
409 {
410 u_char *blob;
411 size_t len;
412 int r;
413
414 debug3("%s: revoke type %s", __func__, sshkey_type(key));
415 if ((r = plain_key_blob(key, &blob, &len)) != 0)
416 return r;
417 return revoke_blob(&krl->revoked_keys, blob, len);
418 }
419
420 static int
revoke_by_hash(struct revoked_blob_tree * target,const u_char * p,size_t len)421 revoke_by_hash(struct revoked_blob_tree *target, const u_char *p, size_t len)
422 {
423 u_char *blob;
424 int r;
425
426 /* need to copy hash, as revoke_blob steals ownership */
427 if ((blob = malloc(len)) == NULL)
428 return SSH_ERR_SYSTEM_ERROR;
429 memcpy(blob, p, len);
430 if ((r = revoke_blob(target, blob, len)) != 0) {
431 free(blob);
432 return r;
433 }
434 return 0;
435 }
436
437 int
ssh_krl_revoke_key_sha1(struct ssh_krl * krl,const u_char * p,size_t len)438 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const u_char *p, size_t len)
439 {
440 debug3("%s: revoke by sha1", __func__);
441 if (len != 20)
442 return SSH_ERR_INVALID_FORMAT;
443 return revoke_by_hash(&krl->revoked_sha1s, p, len);
444 }
445
446 int
ssh_krl_revoke_key_sha256(struct ssh_krl * krl,const u_char * p,size_t len)447 ssh_krl_revoke_key_sha256(struct ssh_krl *krl, const u_char *p, size_t len)
448 {
449 debug3("%s: revoke by sha256", __func__);
450 if (len != 32)
451 return SSH_ERR_INVALID_FORMAT;
452 return revoke_by_hash(&krl->revoked_sha256s, p, len);
453 }
454
455 int
ssh_krl_revoke_key(struct ssh_krl * krl,const struct sshkey * key)456 ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key)
457 {
458 /* XXX replace with SHA256? */
459 if (!sshkey_is_cert(key))
460 return ssh_krl_revoke_key_explicit(krl, key);
461
462 if (key->cert->serial == 0) {
463 return ssh_krl_revoke_cert_by_key_id(krl,
464 key->cert->signature_key,
465 key->cert->key_id);
466 } else {
467 return ssh_krl_revoke_cert_by_serial(krl,
468 key->cert->signature_key,
469 key->cert->serial);
470 }
471 }
472
473 /*
474 * Select the most compact section type to emit next in a KRL based on
475 * the current section type, the run length of contiguous revoked serial
476 * numbers and the gaps from the last and to the next revoked serial.
477 * Applies a mostly-accurate bit cost model to select the section type
478 * that will minimise the size of the resultant KRL.
479 */
480 static int
choose_next_state(int current_state,u_int64_t contig,int final,u_int64_t last_gap,u_int64_t next_gap,int * force_new_section)481 choose_next_state(int current_state, u_int64_t contig, int final,
482 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section)
483 {
484 int new_state;
485 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart;
486
487 /*
488 * Avoid unsigned overflows.
489 * The limits are high enough to avoid confusing the calculations.
490 */
491 contig = MINIMUM(contig, 1ULL<<31);
492 last_gap = MINIMUM(last_gap, 1ULL<<31);
493 next_gap = MINIMUM(next_gap, 1ULL<<31);
494
495 /*
496 * Calculate the cost to switch from the current state to candidates.
497 * NB. range sections only ever contain a single range, so their
498 * switching cost is independent of the current_state.
499 */
500 cost_list = cost_bitmap = cost_bitmap_restart = 0;
501 cost_range = 8;
502 switch (current_state) {
503 case KRL_SECTION_CERT_SERIAL_LIST:
504 cost_bitmap_restart = cost_bitmap = 8 + 64;
505 break;
506 case KRL_SECTION_CERT_SERIAL_BITMAP:
507 cost_list = 8;
508 cost_bitmap_restart = 8 + 64;
509 break;
510 case KRL_SECTION_CERT_SERIAL_RANGE:
511 case 0:
512 cost_bitmap_restart = cost_bitmap = 8 + 64;
513 cost_list = 8;
514 }
515
516 /* Estimate base cost in bits of each section type */
517 cost_list += 64 * contig + (final ? 0 : 8+64);
518 cost_range += (2 * 64) + (final ? 0 : 8+64);
519 cost_bitmap += last_gap + contig + (final ? 0 : MINIMUM(next_gap, 8+64));
520 cost_bitmap_restart += contig + (final ? 0 : MINIMUM(next_gap, 8+64));
521
522 /* Convert to byte costs for actual comparison */
523 cost_list = (cost_list + 7) / 8;
524 cost_bitmap = (cost_bitmap + 7) / 8;
525 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8;
526 cost_range = (cost_range + 7) / 8;
527
528 /* Now pick the best choice */
529 *force_new_section = 0;
530 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
531 cost = cost_bitmap;
532 if (cost_range < cost) {
533 new_state = KRL_SECTION_CERT_SERIAL_RANGE;
534 cost = cost_range;
535 }
536 if (cost_list < cost) {
537 new_state = KRL_SECTION_CERT_SERIAL_LIST;
538 cost = cost_list;
539 }
540 if (cost_bitmap_restart < cost) {
541 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
542 *force_new_section = 1;
543 cost = cost_bitmap_restart;
544 }
545 KRL_DBG(("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:"
546 "list %llu range %llu bitmap %llu new bitmap %llu, "
547 "selected 0x%02x%s", __func__, (long long unsigned)contig,
548 (long long unsigned)last_gap, (long long unsigned)next_gap, final,
549 (long long unsigned)cost_list, (long long unsigned)cost_range,
550 (long long unsigned)cost_bitmap,
551 (long long unsigned)cost_bitmap_restart, new_state,
552 *force_new_section ? " restart" : ""));
553 return new_state;
554 }
555
556 static int
put_bitmap(struct sshbuf * buf,struct bitmap * bitmap)557 put_bitmap(struct sshbuf *buf, struct bitmap *bitmap)
558 {
559 size_t len;
560 u_char *blob;
561 int r;
562
563 len = bitmap_nbytes(bitmap);
564 if ((blob = malloc(len)) == NULL)
565 return SSH_ERR_ALLOC_FAIL;
566 if (bitmap_to_string(bitmap, blob, len) != 0) {
567 free(blob);
568 return SSH_ERR_INTERNAL_ERROR;
569 }
570 r = sshbuf_put_bignum2_bytes(buf, blob, len);
571 free(blob);
572 return r;
573 }
574
575 /* Generate a KRL_SECTION_CERTIFICATES KRL section */
576 static int
revoked_certs_generate(struct revoked_certs * rc,struct sshbuf * buf)577 revoked_certs_generate(struct revoked_certs *rc, struct sshbuf *buf)
578 {
579 int final, force_new_sect, r = SSH_ERR_INTERNAL_ERROR;
580 u_int64_t i, contig, gap, last = 0, bitmap_start = 0;
581 struct revoked_serial *rs, *nrs;
582 struct revoked_key_id *rki;
583 int next_state, state = 0;
584 struct sshbuf *sect;
585 struct bitmap *bitmap = NULL;
586
587 if ((sect = sshbuf_new()) == NULL)
588 return SSH_ERR_ALLOC_FAIL;
589
590 /* Store the header: optional CA scope key, reserved */
591 if (rc->ca_key == NULL) {
592 if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
593 goto out;
594 } else {
595 if ((r = sshkey_puts(rc->ca_key, buf)) != 0)
596 goto out;
597 }
598 if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
599 goto out;
600
601 /* Store the revoked serials. */
602 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials);
603 rs != NULL;
604 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) {
605 KRL_DBG(("%s: serial %llu:%llu state 0x%02x", __func__,
606 (long long unsigned)rs->lo, (long long unsigned)rs->hi,
607 state));
608
609 /* Check contiguous length and gap to next section (if any) */
610 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
611 final = nrs == NULL;
612 gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
613 contig = 1 + (rs->hi - rs->lo);
614
615 /* Choose next state based on these */
616 next_state = choose_next_state(state, contig, final,
617 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
618
619 /*
620 * If the current section is a range section or has a different
621 * type to the next section, then finish it off now.
622 */
623 if (state != 0 && (force_new_sect || next_state != state ||
624 state == KRL_SECTION_CERT_SERIAL_RANGE)) {
625 KRL_DBG(("%s: finish state 0x%02x", __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 if ((r = put_bitmap(sect, bitmap)) != 0)
632 goto out;
633 bitmap_free(bitmap);
634 bitmap = NULL;
635 break;
636 }
637 if ((r = sshbuf_put_u8(buf, state)) != 0 ||
638 (r = sshbuf_put_stringb(buf, sect)) != 0)
639 goto out;
640 sshbuf_reset(sect);
641 }
642
643 /* If we are starting a new section then prepare it now */
644 if (next_state != state || force_new_sect) {
645 KRL_DBG(("%s: start state 0x%02x", __func__,
646 next_state));
647 state = next_state;
648 sshbuf_reset(sect);
649 switch (state) {
650 case KRL_SECTION_CERT_SERIAL_LIST:
651 case KRL_SECTION_CERT_SERIAL_RANGE:
652 break;
653 case KRL_SECTION_CERT_SERIAL_BITMAP:
654 if ((bitmap = bitmap_new()) == NULL) {
655 r = SSH_ERR_ALLOC_FAIL;
656 goto out;
657 }
658 bitmap_start = rs->lo;
659 if ((r = sshbuf_put_u64(sect,
660 bitmap_start)) != 0)
661 goto out;
662 break;
663 }
664 }
665
666 /* Perform section-specific processing */
667 switch (state) {
668 case KRL_SECTION_CERT_SERIAL_LIST:
669 for (i = 0; i < contig; i++) {
670 if ((r = sshbuf_put_u64(sect, rs->lo + i)) != 0)
671 goto out;
672 }
673 break;
674 case KRL_SECTION_CERT_SERIAL_RANGE:
675 if ((r = sshbuf_put_u64(sect, rs->lo)) != 0 ||
676 (r = sshbuf_put_u64(sect, rs->hi)) != 0)
677 goto out;
678 break;
679 case KRL_SECTION_CERT_SERIAL_BITMAP:
680 if (rs->lo - bitmap_start > INT_MAX) {
681 error("%s: insane bitmap gap", __func__);
682 goto out;
683 }
684 for (i = 0; i < contig; i++) {
685 if (bitmap_set_bit(bitmap,
686 rs->lo + i - bitmap_start) != 0) {
687 r = SSH_ERR_ALLOC_FAIL;
688 goto out;
689 }
690 }
691 break;
692 }
693 last = rs->hi;
694 }
695 /* Flush the remaining section, if any */
696 if (state != 0) {
697 KRL_DBG(("%s: serial final flush for state 0x%02x",
698 __func__, state));
699 switch (state) {
700 case KRL_SECTION_CERT_SERIAL_LIST:
701 case KRL_SECTION_CERT_SERIAL_RANGE:
702 break;
703 case KRL_SECTION_CERT_SERIAL_BITMAP:
704 if ((r = put_bitmap(sect, bitmap)) != 0)
705 goto out;
706 bitmap_free(bitmap);
707 bitmap = NULL;
708 break;
709 }
710 if ((r = sshbuf_put_u8(buf, state)) != 0 ||
711 (r = sshbuf_put_stringb(buf, sect)) != 0)
712 goto out;
713 }
714 KRL_DBG(("%s: serial done ", __func__));
715
716 /* Now output a section for any revocations by key ID */
717 sshbuf_reset(sect);
718 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
719 KRL_DBG(("%s: key ID %s", __func__, rki->key_id));
720 if ((r = sshbuf_put_cstring(sect, rki->key_id)) != 0)
721 goto out;
722 }
723 if (sshbuf_len(sect) != 0) {
724 if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERT_KEY_ID)) != 0 ||
725 (r = sshbuf_put_stringb(buf, sect)) != 0)
726 goto out;
727 }
728 r = 0;
729 out:
730 bitmap_free(bitmap);
731 sshbuf_free(sect);
732 return r;
733 }
734
735 int
ssh_krl_to_blob(struct ssh_krl * krl,struct sshbuf * buf,struct sshkey ** sign_keys,u_int nsign_keys)736 ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
737 struct sshkey **sign_keys, u_int nsign_keys)
738 {
739 int r = SSH_ERR_INTERNAL_ERROR;
740 struct revoked_certs *rc;
741 struct revoked_blob *rb;
742 struct sshbuf *sect;
743 u_char *sblob = NULL;
744 size_t slen, i;
745
746 if (krl->generated_date == 0)
747 krl->generated_date = time(NULL);
748
749 if ((sect = sshbuf_new()) == NULL)
750 return SSH_ERR_ALLOC_FAIL;
751
752 /* Store the header */
753 if ((r = sshbuf_put(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1)) != 0 ||
754 (r = sshbuf_put_u32(buf, KRL_FORMAT_VERSION)) != 0 ||
755 (r = sshbuf_put_u64(buf, krl->krl_version)) != 0 ||
756 (r = sshbuf_put_u64(buf, krl->generated_date)) != 0 ||
757 (r = sshbuf_put_u64(buf, krl->flags)) != 0 ||
758 (r = sshbuf_put_string(buf, NULL, 0)) != 0 ||
759 (r = sshbuf_put_cstring(buf, krl->comment)) != 0)
760 goto out;
761
762 /* Store sections for revoked certificates */
763 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
764 sshbuf_reset(sect);
765 if ((r = revoked_certs_generate(rc, sect)) != 0)
766 goto out;
767 if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERTIFICATES)) != 0 ||
768 (r = sshbuf_put_stringb(buf, sect)) != 0)
769 goto out;
770 }
771
772 /* Finally, output sections for revocations by public key/hash */
773 sshbuf_reset(sect);
774 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
775 KRL_DBG(("%s: key len %zu ", __func__, rb->len));
776 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
777 goto out;
778 }
779 if (sshbuf_len(sect) != 0) {
780 if ((r = sshbuf_put_u8(buf, KRL_SECTION_EXPLICIT_KEY)) != 0 ||
781 (r = sshbuf_put_stringb(buf, sect)) != 0)
782 goto out;
783 }
784 sshbuf_reset(sect);
785 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
786 KRL_DBG(("%s: hash len %zu ", __func__, rb->len));
787 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
788 goto out;
789 }
790 if (sshbuf_len(sect) != 0) {
791 if ((r = sshbuf_put_u8(buf,
792 KRL_SECTION_FINGERPRINT_SHA1)) != 0 ||
793 (r = sshbuf_put_stringb(buf, sect)) != 0)
794 goto out;
795 }
796 sshbuf_reset(sect);
797 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) {
798 KRL_DBG(("%s: hash len %zu ", __func__, rb->len));
799 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
800 goto out;
801 }
802 if (sshbuf_len(sect) != 0) {
803 if ((r = sshbuf_put_u8(buf,
804 KRL_SECTION_FINGERPRINT_SHA256)) != 0 ||
805 (r = sshbuf_put_stringb(buf, sect)) != 0)
806 goto out;
807 }
808
809 for (i = 0; i < nsign_keys; i++) {
810 KRL_DBG(("%s: signature key %s", __func__,
811 sshkey_ssh_name(sign_keys[i])));
812 if ((r = sshbuf_put_u8(buf, KRL_SECTION_SIGNATURE)) != 0 ||
813 (r = sshkey_puts(sign_keys[i], buf)) != 0)
814 goto out;
815
816 if ((r = sshkey_sign(sign_keys[i], &sblob, &slen,
817 sshbuf_ptr(buf), sshbuf_len(buf), NULL, NULL, 0)) != 0)
818 goto out;
819 KRL_DBG(("%s: signature sig len %zu", __func__, slen));
820 if ((r = sshbuf_put_string(buf, sblob, slen)) != 0)
821 goto out;
822 }
823
824 r = 0;
825 out:
826 free(sblob);
827 sshbuf_free(sect);
828 return r;
829 }
830
831 static void
format_timestamp(u_int64_t timestamp,char * ts,size_t nts)832 format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
833 {
834 time_t t;
835 struct tm *tm;
836
837 t = timestamp;
838 tm = localtime(&t);
839 if (tm == NULL)
840 strlcpy(ts, "<INVALID>", nts);
841 else {
842 *ts = '\0';
843 strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
844 }
845 }
846
847 static int
parse_revoked_certs(struct sshbuf * buf,struct ssh_krl * krl)848 parse_revoked_certs(struct sshbuf *buf, struct ssh_krl *krl)
849 {
850 int r = SSH_ERR_INTERNAL_ERROR;
851 u_char type;
852 const u_char *blob;
853 size_t blen, nbits;
854 struct sshbuf *subsect = NULL;
855 u_int64_t serial, serial_lo, serial_hi;
856 struct bitmap *bitmap = NULL;
857 char *key_id = NULL;
858 struct sshkey *ca_key = NULL;
859
860 if ((subsect = sshbuf_new()) == NULL)
861 return SSH_ERR_ALLOC_FAIL;
862
863 /* Header: key, reserved */
864 if ((r = sshbuf_get_string_direct(buf, &blob, &blen)) != 0 ||
865 (r = sshbuf_skip_string(buf)) != 0)
866 goto out;
867 if (blen != 0 && (r = sshkey_from_blob(blob, blen, &ca_key)) != 0)
868 goto out;
869
870 while (sshbuf_len(buf) > 0) {
871 sshbuf_free(subsect);
872 subsect = NULL;
873 if ((r = sshbuf_get_u8(buf, &type)) != 0 ||
874 (r = sshbuf_froms(buf, &subsect)) != 0)
875 goto out;
876 KRL_DBG(("%s: subsection type 0x%02x", __func__, type));
877 /* sshbuf_dump(subsect, stderr); */
878
879 switch (type) {
880 case KRL_SECTION_CERT_SERIAL_LIST:
881 while (sshbuf_len(subsect) > 0) {
882 if ((r = sshbuf_get_u64(subsect, &serial)) != 0)
883 goto out;
884 if ((r = ssh_krl_revoke_cert_by_serial(krl,
885 ca_key, serial)) != 0)
886 goto out;
887 }
888 break;
889 case KRL_SECTION_CERT_SERIAL_RANGE:
890 if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
891 (r = sshbuf_get_u64(subsect, &serial_hi)) != 0)
892 goto out;
893 if ((r = ssh_krl_revoke_cert_by_serial_range(krl,
894 ca_key, serial_lo, serial_hi)) != 0)
895 goto out;
896 break;
897 case KRL_SECTION_CERT_SERIAL_BITMAP:
898 if ((bitmap = bitmap_new()) == NULL) {
899 r = SSH_ERR_ALLOC_FAIL;
900 goto out;
901 }
902 if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
903 (r = sshbuf_get_bignum2_bytes_direct(subsect,
904 &blob, &blen)) != 0)
905 goto out;
906 if (bitmap_from_string(bitmap, blob, blen) != 0) {
907 r = SSH_ERR_INVALID_FORMAT;
908 goto out;
909 }
910 nbits = bitmap_nbits(bitmap);
911 for (serial = 0; serial < (u_int64_t)nbits; serial++) {
912 if (serial > 0 && serial_lo + serial == 0) {
913 error("%s: bitmap wraps u64", __func__);
914 r = SSH_ERR_INVALID_FORMAT;
915 goto out;
916 }
917 if (!bitmap_test_bit(bitmap, serial))
918 continue;
919 if ((r = ssh_krl_revoke_cert_by_serial(krl,
920 ca_key, serial_lo + serial)) != 0)
921 goto out;
922 }
923 bitmap_free(bitmap);
924 bitmap = NULL;
925 break;
926 case KRL_SECTION_CERT_KEY_ID:
927 while (sshbuf_len(subsect) > 0) {
928 if ((r = sshbuf_get_cstring(subsect,
929 &key_id, NULL)) != 0)
930 goto out;
931 if ((r = ssh_krl_revoke_cert_by_key_id(krl,
932 ca_key, key_id)) != 0)
933 goto out;
934 free(key_id);
935 key_id = NULL;
936 }
937 break;
938 default:
939 error("Unsupported KRL certificate section %u", type);
940 r = SSH_ERR_INVALID_FORMAT;
941 goto out;
942 }
943 if (sshbuf_len(subsect) > 0) {
944 error("KRL certificate section contains unparsed data");
945 r = SSH_ERR_INVALID_FORMAT;
946 goto out;
947 }
948 }
949
950 r = 0;
951 out:
952 if (bitmap != NULL)
953 bitmap_free(bitmap);
954 free(key_id);
955 sshkey_free(ca_key);
956 sshbuf_free(subsect);
957 return r;
958 }
959
960 static int
blob_section(struct sshbuf * sect,struct revoked_blob_tree * target_tree,size_t expected_len)961 blob_section(struct sshbuf *sect, struct revoked_blob_tree *target_tree,
962 size_t expected_len)
963 {
964 u_char *rdata = NULL;
965 size_t rlen = 0;
966 int r;
967
968 while (sshbuf_len(sect) > 0) {
969 if ((r = sshbuf_get_string(sect, &rdata, &rlen)) != 0)
970 return r;
971 if (expected_len != 0 && rlen != expected_len) {
972 error("%s: bad length", __func__);
973 free(rdata);
974 return SSH_ERR_INVALID_FORMAT;
975 }
976 if ((r = revoke_blob(target_tree, rdata, rlen)) != 0) {
977 free(rdata);
978 return r;
979 }
980 }
981 return 0;
982 }
983
984 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
985 int
ssh_krl_from_blob(struct sshbuf * buf,struct ssh_krl ** krlp,const struct sshkey ** sign_ca_keys,size_t nsign_ca_keys)986 ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
987 const struct sshkey **sign_ca_keys, size_t nsign_ca_keys)
988 {
989 struct sshbuf *copy = NULL, *sect = NULL;
990 struct ssh_krl *krl = NULL;
991 char timestamp[64];
992 int r = SSH_ERR_INTERNAL_ERROR, sig_seen;
993 struct sshkey *key = NULL, **ca_used = NULL, **tmp_ca_used;
994 u_char type;
995 const u_char *blob;
996 size_t i, j, sig_off, sects_off, blen, nca_used;
997 u_int format_version;
998
999 nca_used = 0;
1000 *krlp = NULL;
1001 if (sshbuf_len(buf) < sizeof(KRL_MAGIC) - 1 ||
1002 memcmp(sshbuf_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
1003 debug3("%s: not a KRL", __func__);
1004 return SSH_ERR_KRL_BAD_MAGIC;
1005 }
1006
1007 /* Take a copy of the KRL buffer so we can verify its signature later */
1008 if ((copy = sshbuf_fromb(buf)) == NULL) {
1009 r = SSH_ERR_ALLOC_FAIL;
1010 goto out;
1011 }
1012 if ((r = sshbuf_consume(copy, sizeof(KRL_MAGIC) - 1)) != 0)
1013 goto out;
1014
1015 if ((krl = ssh_krl_init()) == NULL) {
1016 error("%s: alloc failed", __func__);
1017 goto out;
1018 }
1019
1020 if ((r = sshbuf_get_u32(copy, &format_version)) != 0)
1021 goto out;
1022 if (format_version != KRL_FORMAT_VERSION) {
1023 r = SSH_ERR_INVALID_FORMAT;
1024 goto out;
1025 }
1026 if ((r = sshbuf_get_u64(copy, &krl->krl_version)) != 0 ||
1027 (r = sshbuf_get_u64(copy, &krl->generated_date)) != 0 ||
1028 (r = sshbuf_get_u64(copy, &krl->flags)) != 0 ||
1029 (r = sshbuf_skip_string(copy)) != 0 ||
1030 (r = sshbuf_get_cstring(copy, &krl->comment, NULL)) != 0)
1031 goto out;
1032
1033 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1034 debug("KRL version %llu generated at %s%s%s",
1035 (long long unsigned)krl->krl_version, timestamp,
1036 *krl->comment ? ": " : "", krl->comment);
1037
1038 /*
1039 * 1st pass: verify signatures, if any. This is done to avoid
1040 * detailed parsing of data whose provenance is unverified.
1041 */
1042 sig_seen = 0;
1043 if (sshbuf_len(buf) < sshbuf_len(copy)) {
1044 /* Shouldn't happen */
1045 r = SSH_ERR_INTERNAL_ERROR;
1046 goto out;
1047 }
1048 sects_off = sshbuf_len(buf) - sshbuf_len(copy);
1049 while (sshbuf_len(copy) > 0) {
1050 if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1051 (r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0)
1052 goto out;
1053 KRL_DBG(("%s: first pass, section 0x%02x", __func__, type));
1054 if (type != KRL_SECTION_SIGNATURE) {
1055 if (sig_seen) {
1056 error("KRL contains non-signature section "
1057 "after signature");
1058 r = SSH_ERR_INVALID_FORMAT;
1059 goto out;
1060 }
1061 /* Not interested for now. */
1062 continue;
1063 }
1064 sig_seen = 1;
1065 /* First string component is the signing key */
1066 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
1067 r = SSH_ERR_INVALID_FORMAT;
1068 goto out;
1069 }
1070 if (sshbuf_len(buf) < sshbuf_len(copy)) {
1071 /* Shouldn't happen */
1072 r = SSH_ERR_INTERNAL_ERROR;
1073 goto out;
1074 }
1075 sig_off = sshbuf_len(buf) - sshbuf_len(copy);
1076 /* Second string component is the signature itself */
1077 if ((r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0) {
1078 r = SSH_ERR_INVALID_FORMAT;
1079 goto out;
1080 }
1081 /* Check signature over entire KRL up to this point */
1082 if ((r = sshkey_verify(key, blob, blen,
1083 sshbuf_ptr(buf), sig_off, NULL, 0, NULL)) != 0)
1084 goto out;
1085 /* Check if this key has already signed this KRL */
1086 for (i = 0; i < nca_used; i++) {
1087 if (sshkey_equal(ca_used[i], key)) {
1088 error("KRL signed more than once with "
1089 "the same key");
1090 r = SSH_ERR_INVALID_FORMAT;
1091 goto out;
1092 }
1093 }
1094 /* Record keys used to sign the KRL */
1095 tmp_ca_used = recallocarray(ca_used, nca_used, nca_used + 1,
1096 sizeof(*ca_used));
1097 if (tmp_ca_used == NULL) {
1098 r = SSH_ERR_ALLOC_FAIL;
1099 goto out;
1100 }
1101 ca_used = tmp_ca_used;
1102 ca_used[nca_used++] = key;
1103 key = NULL;
1104 }
1105
1106 if (sshbuf_len(copy) != 0) {
1107 /* Shouldn't happen */
1108 r = SSH_ERR_INTERNAL_ERROR;
1109 goto out;
1110 }
1111
1112 /*
1113 * 2nd pass: parse and load the KRL, skipping the header to the point
1114 * where the section start.
1115 */
1116 sshbuf_free(copy);
1117 if ((copy = sshbuf_fromb(buf)) == NULL) {
1118 r = SSH_ERR_ALLOC_FAIL;
1119 goto out;
1120 }
1121 if ((r = sshbuf_consume(copy, sects_off)) != 0)
1122 goto out;
1123 while (sshbuf_len(copy) > 0) {
1124 sshbuf_free(sect);
1125 sect = NULL;
1126 if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1127 (r = sshbuf_froms(copy, §)) != 0)
1128 goto out;
1129 KRL_DBG(("%s: second pass, section 0x%02x", __func__, type));
1130
1131 switch (type) {
1132 case KRL_SECTION_CERTIFICATES:
1133 if ((r = parse_revoked_certs(sect, krl)) != 0)
1134 goto out;
1135 break;
1136 case KRL_SECTION_EXPLICIT_KEY:
1137 if ((r = blob_section(sect,
1138 &krl->revoked_keys, 0)) != 0)
1139 goto out;
1140 break;
1141 case KRL_SECTION_FINGERPRINT_SHA1:
1142 if ((r = blob_section(sect,
1143 &krl->revoked_sha1s, 20)) != 0)
1144 goto out;
1145 break;
1146 case KRL_SECTION_FINGERPRINT_SHA256:
1147 if ((r = blob_section(sect,
1148 &krl->revoked_sha256s, 32)) != 0)
1149 goto out;
1150 break;
1151 case KRL_SECTION_SIGNATURE:
1152 /* Handled above, but still need to stay in synch */
1153 sshbuf_free(sect);
1154 sect = NULL;
1155 if ((r = sshbuf_skip_string(copy)) != 0)
1156 goto out;
1157 break;
1158 default:
1159 error("Unsupported KRL section %u", type);
1160 r = SSH_ERR_INVALID_FORMAT;
1161 goto out;
1162 }
1163 if (sect != NULL && sshbuf_len(sect) > 0) {
1164 error("KRL section contains unparsed data");
1165 r = SSH_ERR_INVALID_FORMAT;
1166 goto out;
1167 }
1168 }
1169
1170 /* Check that the key(s) used to sign the KRL weren't revoked */
1171 sig_seen = 0;
1172 for (i = 0; i < nca_used; i++) {
1173 if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1174 sig_seen = 1;
1175 else {
1176 sshkey_free(ca_used[i]);
1177 ca_used[i] = NULL;
1178 }
1179 }
1180 if (nca_used && !sig_seen) {
1181 error("All keys used to sign KRL were revoked");
1182 r = SSH_ERR_KEY_REVOKED;
1183 goto out;
1184 }
1185
1186 /* If we have CA keys, then verify that one was used to sign the KRL */
1187 if (sig_seen && nsign_ca_keys != 0) {
1188 sig_seen = 0;
1189 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1190 for (j = 0; j < nca_used; j++) {
1191 if (ca_used[j] == NULL)
1192 continue;
1193 if (sshkey_equal(ca_used[j], sign_ca_keys[i])) {
1194 sig_seen = 1;
1195 break;
1196 }
1197 }
1198 }
1199 if (!sig_seen) {
1200 r = SSH_ERR_SIGNATURE_INVALID;
1201 error("KRL not signed with any trusted key");
1202 goto out;
1203 }
1204 }
1205
1206 *krlp = krl;
1207 r = 0;
1208 out:
1209 if (r != 0)
1210 ssh_krl_free(krl);
1211 for (i = 0; i < nca_used; i++)
1212 sshkey_free(ca_used[i]);
1213 free(ca_used);
1214 sshkey_free(key);
1215 sshbuf_free(copy);
1216 sshbuf_free(sect);
1217 return r;
1218 }
1219
1220 /* Checks certificate serial number and key ID revocation */
1221 static int
is_cert_revoked(const struct sshkey * key,struct revoked_certs * rc)1222 is_cert_revoked(const struct sshkey *key, struct revoked_certs *rc)
1223 {
1224 struct revoked_serial rs, *ers;
1225 struct revoked_key_id rki, *erki;
1226
1227 /* Check revocation by cert key ID */
1228 memset(&rki, 0, sizeof(rki));
1229 rki.key_id = key->cert->key_id;
1230 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1231 if (erki != NULL) {
1232 KRL_DBG(("%s: revoked by key ID", __func__));
1233 return SSH_ERR_KEY_REVOKED;
1234 }
1235
1236 /*
1237 * Zero serials numbers are ignored (it's the default when the
1238 * CA doesn't specify one).
1239 */
1240 if (key->cert->serial == 0)
1241 return 0;
1242
1243 memset(&rs, 0, sizeof(rs));
1244 rs.lo = rs.hi = key->cert->serial;
1245 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1246 if (ers != NULL) {
1247 KRL_DBG(("%s: revoked serial %llu matched %llu:%llu", __func__,
1248 key->cert->serial, ers->lo, ers->hi));
1249 return SSH_ERR_KEY_REVOKED;
1250 }
1251 return 0;
1252 }
1253
1254 /* Checks whether a given key/cert is revoked. Does not check its CA */
1255 static int
is_key_revoked(struct ssh_krl * krl,const struct sshkey * key)1256 is_key_revoked(struct ssh_krl *krl, const struct sshkey *key)
1257 {
1258 struct revoked_blob rb, *erb;
1259 struct revoked_certs *rc;
1260 int r;
1261
1262 /* Check explicitly revoked hashes first */
1263 memset(&rb, 0, sizeof(rb));
1264 if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA1,
1265 &rb.blob, &rb.len)) != 0)
1266 return r;
1267 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1268 free(rb.blob);
1269 if (erb != NULL) {
1270 KRL_DBG(("%s: revoked by key SHA1", __func__));
1271 return SSH_ERR_KEY_REVOKED;
1272 }
1273 memset(&rb, 0, sizeof(rb));
1274 if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA256,
1275 &rb.blob, &rb.len)) != 0)
1276 return r;
1277 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha256s, &rb);
1278 free(rb.blob);
1279 if (erb != NULL) {
1280 KRL_DBG(("%s: revoked by key SHA256", __func__));
1281 return SSH_ERR_KEY_REVOKED;
1282 }
1283
1284 /* Next, explicit keys */
1285 memset(&rb, 0, sizeof(rb));
1286 if ((r = plain_key_blob(key, &rb.blob, &rb.len)) != 0)
1287 return r;
1288 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1289 free(rb.blob);
1290 if (erb != NULL) {
1291 KRL_DBG(("%s: revoked by explicit key", __func__));
1292 return SSH_ERR_KEY_REVOKED;
1293 }
1294
1295 if (!sshkey_is_cert(key))
1296 return 0;
1297
1298 /* Check cert revocation for the specified CA */
1299 if ((r = revoked_certs_for_ca_key(krl, key->cert->signature_key,
1300 &rc, 0)) != 0)
1301 return r;
1302 if (rc != NULL) {
1303 if ((r = is_cert_revoked(key, rc)) != 0)
1304 return r;
1305 }
1306 /* Check cert revocation for the wildcard CA */
1307 if ((r = revoked_certs_for_ca_key(krl, NULL, &rc, 0)) != 0)
1308 return r;
1309 if (rc != NULL) {
1310 if ((r = is_cert_revoked(key, rc)) != 0)
1311 return r;
1312 }
1313
1314 KRL_DBG(("%s: %llu no match", __func__, key->cert->serial));
1315 return 0;
1316 }
1317
1318 int
ssh_krl_check_key(struct ssh_krl * krl,const struct sshkey * key)1319 ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key)
1320 {
1321 int r;
1322
1323 KRL_DBG(("%s: checking key", __func__));
1324 if ((r = is_key_revoked(krl, key)) != 0)
1325 return r;
1326 if (sshkey_is_cert(key)) {
1327 debug2("%s: checking CA key", __func__);
1328 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1329 return r;
1330 }
1331 KRL_DBG(("%s: key okay", __func__));
1332 return 0;
1333 }
1334
1335 int
ssh_krl_file_contains_key(const char * path,const struct sshkey * key)1336 ssh_krl_file_contains_key(const char *path, const struct sshkey *key)
1337 {
1338 struct sshbuf *krlbuf = NULL;
1339 struct ssh_krl *krl = NULL;
1340 int oerrno = 0, r;
1341
1342 if (path == NULL)
1343 return 0;
1344 if ((r = sshbuf_load_file(path, &krlbuf)) != 0) {
1345 oerrno = errno;
1346 goto out;
1347 }
1348 if ((r = ssh_krl_from_blob(krlbuf, &krl, NULL, 0)) != 0)
1349 goto out;
1350 debug2("%s: checking KRL %s", __func__, path);
1351 r = ssh_krl_check_key(krl, key);
1352 out:
1353 sshbuf_free(krlbuf);
1354 ssh_krl_free(krl);
1355 if (r != 0)
1356 errno = oerrno;
1357 return r;
1358 }
1359
1360 int
krl_dump(struct ssh_krl * krl,FILE * f)1361 krl_dump(struct ssh_krl *krl, FILE *f)
1362 {
1363 struct sshkey *key = NULL;
1364 struct revoked_blob *rb;
1365 struct revoked_certs *rc;
1366 struct revoked_serial *rs;
1367 struct revoked_key_id *rki;
1368 int r, ret = 0;
1369 char *fp, timestamp[64];
1370
1371 /* Try to print in a KRL spec-compatible format */
1372 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1373 fprintf(f, "# KRL version %llu\n",
1374 (unsigned long long)krl->krl_version);
1375 fprintf(f, "# Generated at %s\n", timestamp);
1376 if (krl->comment != NULL && *krl->comment != '\0') {
1377 r = INT_MAX;
1378 asmprintf(&fp, INT_MAX, &r, "%s", krl->comment);
1379 fprintf(f, "# Comment: %s\n", fp);
1380 free(fp);
1381 }
1382 fputc('\n', f);
1383
1384 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
1385 if ((r = sshkey_from_blob(rb->blob, rb->len, &key)) != 0) {
1386 ret = SSH_ERR_INVALID_FORMAT;
1387 error("Parse key in KRL: %s", ssh_err(r));
1388 continue;
1389 }
1390 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
1391 SSH_FP_DEFAULT)) == NULL) {
1392 ret = SSH_ERR_INVALID_FORMAT;
1393 error("sshkey_fingerprint failed");
1394 continue;
1395 }
1396 fprintf(f, "hash: SHA256:%s # %s\n", fp, sshkey_ssh_name(key));
1397 free(fp);
1398 free(key);
1399 }
1400 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) {
1401 fp = tohex(rb->blob, rb->len);
1402 fprintf(f, "hash: SHA256:%s\n", fp);
1403 free(fp);
1404 }
1405 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
1406 /*
1407 * There is not KRL spec keyword for raw SHA1 hashes, so
1408 * print them as comments.
1409 */
1410 fp = tohex(rb->blob, rb->len);
1411 fprintf(f, "# hash SHA1:%s\n", fp);
1412 free(fp);
1413 }
1414
1415 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
1416 fputc('\n', f);
1417 if (rc->ca_key == NULL)
1418 fprintf(f, "# Wildcard CA\n");
1419 else {
1420 if ((fp = sshkey_fingerprint(rc->ca_key,
1421 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) {
1422 ret = SSH_ERR_INVALID_FORMAT;
1423 error("sshkey_fingerprint failed");
1424 continue;
1425 }
1426 fprintf(f, "# CA key %s %s\n",
1427 sshkey_ssh_name(rc->ca_key), fp);
1428 free(fp);
1429 }
1430 RB_FOREACH(rs, revoked_serial_tree, &rc->revoked_serials) {
1431 if (rs->lo == rs->hi) {
1432 fprintf(f, "serial: %llu\n",
1433 (unsigned long long)rs->lo);
1434 } else {
1435 fprintf(f, "serial: %llu-%llu\n",
1436 (unsigned long long)rs->lo,
1437 (unsigned long long)rs->hi);
1438 }
1439 }
1440 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
1441 /*
1442 * We don't want key IDs with embedded newlines to
1443 * mess up the display.
1444 */
1445 r = INT_MAX;
1446 asmprintf(&fp, INT_MAX, &r, "%s", rki->key_id);
1447 fprintf(f, "id: %s\n", fp);
1448 free(fp);
1449 }
1450 }
1451 return ret;
1452 }
1453