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 1.54 2022/04/28 02:53:31 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_f 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(("new CA %s", ca_key == NULL ? "*" : sshkey_type(ca_key)));
245 *rcp = rc;
246 return 0;
247 }
248
249 static int
insert_serial_range(struct revoked_serial_tree * rt,u_int64_t lo,u_int64_t hi)250 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi)
251 {
252 struct revoked_serial rs, *ers, *crs, *irs;
253
254 KRL_DBG(("insert %llu:%llu", lo, hi));
255 memset(&rs, 0, sizeof(rs));
256 rs.lo = lo;
257 rs.hi = hi;
258 ers = RB_NFIND(revoked_serial_tree, rt, &rs);
259 if (ers == NULL || serial_cmp(ers, &rs) != 0) {
260 /* No entry matches. Just insert */
261 if ((irs = malloc(sizeof(rs))) == NULL)
262 return SSH_ERR_ALLOC_FAIL;
263 memcpy(irs, &rs, sizeof(*irs));
264 ers = RB_INSERT(revoked_serial_tree, rt, irs);
265 if (ers != NULL) {
266 KRL_DBG(("bad: ers != NULL"));
267 /* Shouldn't happen */
268 free(irs);
269 return SSH_ERR_INTERNAL_ERROR;
270 }
271 ers = irs;
272 } else {
273 KRL_DBG(("overlap found %llu:%llu", ers->lo, ers->hi));
274 /*
275 * The inserted entry overlaps an existing one. Grow the
276 * existing entry.
277 */
278 if (ers->lo > lo)
279 ers->lo = lo;
280 if (ers->hi < hi)
281 ers->hi = hi;
282 }
283
284 /*
285 * The inserted or revised range might overlap or abut adjacent ones;
286 * coalesce as necessary.
287 */
288
289 /* Check predecessors */
290 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) {
291 KRL_DBG(("pred %llu:%llu", crs->lo, crs->hi));
292 if (ers->lo != 0 && crs->hi < ers->lo - 1)
293 break;
294 /* This entry overlaps. */
295 if (crs->lo < ers->lo) {
296 ers->lo = crs->lo;
297 KRL_DBG(("pred extend %llu:%llu", ers->lo, ers->hi));
298 }
299 RB_REMOVE(revoked_serial_tree, rt, crs);
300 free(crs);
301 }
302 /* Check successors */
303 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) {
304 KRL_DBG(("succ %llu:%llu", crs->lo, crs->hi));
305 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1)
306 break;
307 /* This entry overlaps. */
308 if (crs->hi > ers->hi) {
309 ers->hi = crs->hi;
310 KRL_DBG(("succ extend %llu:%llu", ers->lo, ers->hi));
311 }
312 RB_REMOVE(revoked_serial_tree, rt, crs);
313 free(crs);
314 }
315 KRL_DBG(("done, final %llu:%llu", ers->lo, ers->hi));
316 return 0;
317 }
318
319 int
ssh_krl_revoke_cert_by_serial(struct ssh_krl * krl,const struct sshkey * ca_key,u_int64_t serial)320 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const struct sshkey *ca_key,
321 u_int64_t serial)
322 {
323 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial);
324 }
325
326 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)327 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl,
328 const struct sshkey *ca_key, u_int64_t lo, u_int64_t hi)
329 {
330 struct revoked_certs *rc;
331 int r;
332
333 if (lo > hi || lo == 0)
334 return SSH_ERR_INVALID_ARGUMENT;
335 if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
336 return r;
337 return insert_serial_range(&rc->revoked_serials, lo, hi);
338 }
339
340 int
ssh_krl_revoke_cert_by_key_id(struct ssh_krl * krl,const struct sshkey * ca_key,const char * key_id)341 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const struct sshkey *ca_key,
342 const char *key_id)
343 {
344 struct revoked_key_id *rki, *erki;
345 struct revoked_certs *rc;
346 int r;
347
348 if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
349 return r;
350
351 KRL_DBG(("revoke %s", key_id));
352 if ((rki = calloc(1, sizeof(*rki))) == NULL ||
353 (rki->key_id = strdup(key_id)) == NULL) {
354 free(rki);
355 return SSH_ERR_ALLOC_FAIL;
356 }
357 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki);
358 if (erki != NULL) {
359 free(rki->key_id);
360 free(rki);
361 }
362 return 0;
363 }
364
365 /* Convert "key" to a public key blob without any certificate information */
366 static int
plain_key_blob(const struct sshkey * key,u_char ** blob,size_t * blen)367 plain_key_blob(const struct sshkey *key, u_char **blob, size_t *blen)
368 {
369 struct sshkey *kcopy;
370 int r;
371
372 if ((r = sshkey_from_private(key, &kcopy)) != 0)
373 return r;
374 if (sshkey_is_cert(kcopy)) {
375 if ((r = sshkey_drop_cert(kcopy)) != 0) {
376 sshkey_free(kcopy);
377 return r;
378 }
379 }
380 r = sshkey_to_blob(kcopy, blob, blen);
381 sshkey_free(kcopy);
382 return r;
383 }
384
385 /* Revoke a key blob. Ownership of blob is transferred to the tree */
386 static int
revoke_blob(struct revoked_blob_tree * rbt,u_char * blob,size_t len)387 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, size_t len)
388 {
389 struct revoked_blob *rb, *erb;
390
391 if ((rb = calloc(1, sizeof(*rb))) == NULL)
392 return SSH_ERR_ALLOC_FAIL;
393 rb->blob = blob;
394 rb->len = len;
395 erb = RB_INSERT(revoked_blob_tree, rbt, rb);
396 if (erb != NULL) {
397 free(rb->blob);
398 free(rb);
399 }
400 return 0;
401 }
402
403 int
ssh_krl_revoke_key_explicit(struct ssh_krl * krl,const struct sshkey * key)404 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const struct sshkey *key)
405 {
406 u_char *blob;
407 size_t len;
408 int r;
409
410 debug3_f("revoke type %s", sshkey_type(key));
411 if ((r = plain_key_blob(key, &blob, &len)) != 0)
412 return r;
413 return revoke_blob(&krl->revoked_keys, blob, len);
414 }
415
416 static int
revoke_by_hash(struct revoked_blob_tree * target,const u_char * p,size_t len)417 revoke_by_hash(struct revoked_blob_tree *target, const u_char *p, size_t len)
418 {
419 u_char *blob;
420 int r;
421
422 /* need to copy hash, as revoke_blob steals ownership */
423 if ((blob = malloc(len)) == NULL)
424 return SSH_ERR_SYSTEM_ERROR;
425 memcpy(blob, p, len);
426 if ((r = revoke_blob(target, blob, len)) != 0) {
427 free(blob);
428 return r;
429 }
430 return 0;
431 }
432
433 int
ssh_krl_revoke_key_sha1(struct ssh_krl * krl,const u_char * p,size_t len)434 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const u_char *p, size_t len)
435 {
436 debug3_f("revoke by sha1");
437 if (len != 20)
438 return SSH_ERR_INVALID_FORMAT;
439 return revoke_by_hash(&krl->revoked_sha1s, p, len);
440 }
441
442 int
ssh_krl_revoke_key_sha256(struct ssh_krl * krl,const u_char * p,size_t len)443 ssh_krl_revoke_key_sha256(struct ssh_krl *krl, const u_char *p, size_t len)
444 {
445 debug3_f("revoke by sha256");
446 if (len != 32)
447 return SSH_ERR_INVALID_FORMAT;
448 return revoke_by_hash(&krl->revoked_sha256s, p, len);
449 }
450
451 int
ssh_krl_revoke_key(struct ssh_krl * krl,const struct sshkey * key)452 ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key)
453 {
454 /* XXX replace with SHA256? */
455 if (!sshkey_is_cert(key))
456 return ssh_krl_revoke_key_explicit(krl, key);
457
458 if (key->cert->serial == 0) {
459 return ssh_krl_revoke_cert_by_key_id(krl,
460 key->cert->signature_key,
461 key->cert->key_id);
462 } else {
463 return ssh_krl_revoke_cert_by_serial(krl,
464 key->cert->signature_key,
465 key->cert->serial);
466 }
467 }
468
469 /*
470 * Select the most compact section type to emit next in a KRL based on
471 * the current section type, the run length of contiguous revoked serial
472 * numbers and the gaps from the last and to the next revoked serial.
473 * Applies a mostly-accurate bit cost model to select the section type
474 * that will minimise the size of the resultant KRL.
475 */
476 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)477 choose_next_state(int current_state, u_int64_t contig, int final,
478 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section)
479 {
480 int new_state;
481 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart;
482
483 /*
484 * Avoid unsigned overflows.
485 * The limits are high enough to avoid confusing the calculations.
486 */
487 contig = MINIMUM(contig, 1ULL<<31);
488 last_gap = MINIMUM(last_gap, 1ULL<<31);
489 next_gap = MINIMUM(next_gap, 1ULL<<31);
490
491 /*
492 * Calculate the cost to switch from the current state to candidates.
493 * NB. range sections only ever contain a single range, so their
494 * switching cost is independent of the current_state.
495 */
496 cost_list = cost_bitmap = cost_bitmap_restart = 0;
497 cost_range = 8;
498 switch (current_state) {
499 case KRL_SECTION_CERT_SERIAL_LIST:
500 cost_bitmap_restart = cost_bitmap = 8 + 64;
501 break;
502 case KRL_SECTION_CERT_SERIAL_BITMAP:
503 cost_list = 8;
504 cost_bitmap_restart = 8 + 64;
505 break;
506 case KRL_SECTION_CERT_SERIAL_RANGE:
507 case 0:
508 cost_bitmap_restart = cost_bitmap = 8 + 64;
509 cost_list = 8;
510 }
511
512 /* Estimate base cost in bits of each section type */
513 cost_list += 64 * contig + (final ? 0 : 8+64);
514 cost_range += (2 * 64) + (final ? 0 : 8+64);
515 cost_bitmap += last_gap + contig + (final ? 0 : MINIMUM(next_gap, 8+64));
516 cost_bitmap_restart += contig + (final ? 0 : MINIMUM(next_gap, 8+64));
517
518 /* Convert to byte costs for actual comparison */
519 cost_list = (cost_list + 7) / 8;
520 cost_bitmap = (cost_bitmap + 7) / 8;
521 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8;
522 cost_range = (cost_range + 7) / 8;
523
524 /* Now pick the best choice */
525 *force_new_section = 0;
526 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
527 cost = cost_bitmap;
528 if (cost_range < cost) {
529 new_state = KRL_SECTION_CERT_SERIAL_RANGE;
530 cost = cost_range;
531 }
532 if (cost_list < cost) {
533 new_state = KRL_SECTION_CERT_SERIAL_LIST;
534 cost = cost_list;
535 }
536 if (cost_bitmap_restart < cost) {
537 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
538 *force_new_section = 1;
539 cost = cost_bitmap_restart;
540 }
541 KRL_DBG(("contig %llu last_gap %llu next_gap %llu final %d, costs:"
542 "list %llu range %llu bitmap %llu new bitmap %llu, "
543 "selected 0x%02x%s", (long long unsigned)contig,
544 (long long unsigned)last_gap, (long long unsigned)next_gap, final,
545 (long long unsigned)cost_list, (long long unsigned)cost_range,
546 (long long unsigned)cost_bitmap,
547 (long long unsigned)cost_bitmap_restart, new_state,
548 *force_new_section ? " restart" : ""));
549 return new_state;
550 }
551
552 static int
put_bitmap(struct sshbuf * buf,struct bitmap * bitmap)553 put_bitmap(struct sshbuf *buf, struct bitmap *bitmap)
554 {
555 size_t len;
556 u_char *blob;
557 int r;
558
559 len = bitmap_nbytes(bitmap);
560 if ((blob = malloc(len)) == NULL)
561 return SSH_ERR_ALLOC_FAIL;
562 if (bitmap_to_string(bitmap, blob, len) != 0) {
563 free(blob);
564 return SSH_ERR_INTERNAL_ERROR;
565 }
566 r = sshbuf_put_bignum2_bytes(buf, blob, len);
567 free(blob);
568 return r;
569 }
570
571 /* Generate a KRL_SECTION_CERTIFICATES KRL section */
572 static int
revoked_certs_generate(struct revoked_certs * rc,struct sshbuf * buf)573 revoked_certs_generate(struct revoked_certs *rc, struct sshbuf *buf)
574 {
575 int final, force_new_sect, r = SSH_ERR_INTERNAL_ERROR;
576 u_int64_t i, contig, gap, last = 0, bitmap_start = 0;
577 struct revoked_serial *rs, *nrs;
578 struct revoked_key_id *rki;
579 int next_state, state = 0;
580 struct sshbuf *sect;
581 struct bitmap *bitmap = NULL;
582
583 if ((sect = sshbuf_new()) == NULL)
584 return SSH_ERR_ALLOC_FAIL;
585
586 /* Store the header: optional CA scope key, reserved */
587 if (rc->ca_key == NULL) {
588 if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
589 goto out;
590 } else {
591 if ((r = sshkey_puts(rc->ca_key, buf)) != 0)
592 goto out;
593 }
594 if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
595 goto out;
596
597 /* Store the revoked serials. */
598 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials);
599 rs != NULL;
600 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) {
601 KRL_DBG(("serial %llu:%llu state 0x%02x",
602 (long long unsigned)rs->lo, (long long unsigned)rs->hi,
603 state));
604
605 /* Check contiguous length and gap to next section (if any) */
606 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
607 final = nrs == NULL;
608 gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
609 contig = 1 + (rs->hi - rs->lo);
610
611 /* Choose next state based on these */
612 next_state = choose_next_state(state, contig, final,
613 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
614
615 /*
616 * If the current section is a range section or has a different
617 * type to the next section, then finish it off now.
618 */
619 if (state != 0 && (force_new_sect || next_state != state ||
620 state == KRL_SECTION_CERT_SERIAL_RANGE)) {
621 KRL_DBG(("finish state 0x%02x", state));
622 switch (state) {
623 case KRL_SECTION_CERT_SERIAL_LIST:
624 case KRL_SECTION_CERT_SERIAL_RANGE:
625 break;
626 case KRL_SECTION_CERT_SERIAL_BITMAP:
627 if ((r = put_bitmap(sect, bitmap)) != 0)
628 goto out;
629 bitmap_free(bitmap);
630 bitmap = NULL;
631 break;
632 }
633 if ((r = sshbuf_put_u8(buf, state)) != 0 ||
634 (r = sshbuf_put_stringb(buf, sect)) != 0)
635 goto out;
636 sshbuf_reset(sect);
637 }
638
639 /* If we are starting a new section then prepare it now */
640 if (next_state != state || force_new_sect) {
641 KRL_DBG(("start state 0x%02x",
642 next_state));
643 state = next_state;
644 sshbuf_reset(sect);
645 switch (state) {
646 case KRL_SECTION_CERT_SERIAL_LIST:
647 case KRL_SECTION_CERT_SERIAL_RANGE:
648 break;
649 case KRL_SECTION_CERT_SERIAL_BITMAP:
650 if ((bitmap = bitmap_new()) == NULL) {
651 r = SSH_ERR_ALLOC_FAIL;
652 goto out;
653 }
654 bitmap_start = rs->lo;
655 if ((r = sshbuf_put_u64(sect,
656 bitmap_start)) != 0)
657 goto out;
658 break;
659 }
660 }
661
662 /* Perform section-specific processing */
663 switch (state) {
664 case KRL_SECTION_CERT_SERIAL_LIST:
665 for (i = 0; i < contig; i++) {
666 if ((r = sshbuf_put_u64(sect, rs->lo + i)) != 0)
667 goto out;
668 }
669 break;
670 case KRL_SECTION_CERT_SERIAL_RANGE:
671 if ((r = sshbuf_put_u64(sect, rs->lo)) != 0 ||
672 (r = sshbuf_put_u64(sect, rs->hi)) != 0)
673 goto out;
674 break;
675 case KRL_SECTION_CERT_SERIAL_BITMAP:
676 if (rs->lo - bitmap_start > INT_MAX) {
677 error_f("insane bitmap gap");
678 goto out;
679 }
680 for (i = 0; i < contig; i++) {
681 if (bitmap_set_bit(bitmap,
682 rs->lo + i - bitmap_start) != 0) {
683 r = SSH_ERR_ALLOC_FAIL;
684 goto out;
685 }
686 }
687 break;
688 }
689 last = rs->hi;
690 }
691 /* Flush the remaining section, if any */
692 if (state != 0) {
693 KRL_DBG(("serial final flush for state 0x%02x", state));
694 switch (state) {
695 case KRL_SECTION_CERT_SERIAL_LIST:
696 case KRL_SECTION_CERT_SERIAL_RANGE:
697 break;
698 case KRL_SECTION_CERT_SERIAL_BITMAP:
699 if ((r = put_bitmap(sect, bitmap)) != 0)
700 goto out;
701 bitmap_free(bitmap);
702 bitmap = NULL;
703 break;
704 }
705 if ((r = sshbuf_put_u8(buf, state)) != 0 ||
706 (r = sshbuf_put_stringb(buf, sect)) != 0)
707 goto out;
708 }
709 KRL_DBG(("serial done "));
710
711 /* Now output a section for any revocations by key ID */
712 sshbuf_reset(sect);
713 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
714 KRL_DBG(("key ID %s", rki->key_id));
715 if ((r = sshbuf_put_cstring(sect, rki->key_id)) != 0)
716 goto out;
717 }
718 if (sshbuf_len(sect) != 0) {
719 if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERT_KEY_ID)) != 0 ||
720 (r = sshbuf_put_stringb(buf, sect)) != 0)
721 goto out;
722 }
723 r = 0;
724 out:
725 bitmap_free(bitmap);
726 sshbuf_free(sect);
727 return r;
728 }
729
730 int
ssh_krl_to_blob(struct ssh_krl * krl,struct sshbuf * buf,struct sshkey ** sign_keys,u_int nsign_keys)731 ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
732 struct sshkey **sign_keys, u_int nsign_keys)
733 {
734 int r = SSH_ERR_INTERNAL_ERROR;
735 struct revoked_certs *rc;
736 struct revoked_blob *rb;
737 struct sshbuf *sect;
738 u_char *sblob = NULL;
739 size_t slen, i;
740
741 if (krl->generated_date == 0)
742 krl->generated_date = time(NULL);
743
744 if ((sect = sshbuf_new()) == NULL)
745 return SSH_ERR_ALLOC_FAIL;
746
747 /* Store the header */
748 if ((r = sshbuf_put(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1)) != 0 ||
749 (r = sshbuf_put_u32(buf, KRL_FORMAT_VERSION)) != 0 ||
750 (r = sshbuf_put_u64(buf, krl->krl_version)) != 0 ||
751 (r = sshbuf_put_u64(buf, krl->generated_date)) != 0 ||
752 (r = sshbuf_put_u64(buf, krl->flags)) != 0 ||
753 (r = sshbuf_put_string(buf, NULL, 0)) != 0 ||
754 (r = sshbuf_put_cstring(buf, krl->comment)) != 0)
755 goto out;
756
757 /* Store sections for revoked certificates */
758 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
759 sshbuf_reset(sect);
760 if ((r = revoked_certs_generate(rc, sect)) != 0)
761 goto out;
762 if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERTIFICATES)) != 0 ||
763 (r = sshbuf_put_stringb(buf, sect)) != 0)
764 goto out;
765 }
766
767 /* Finally, output sections for revocations by public key/hash */
768 sshbuf_reset(sect);
769 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
770 KRL_DBG(("key len %zu ", rb->len));
771 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
772 goto out;
773 }
774 if (sshbuf_len(sect) != 0) {
775 if ((r = sshbuf_put_u8(buf, KRL_SECTION_EXPLICIT_KEY)) != 0 ||
776 (r = sshbuf_put_stringb(buf, sect)) != 0)
777 goto out;
778 }
779 sshbuf_reset(sect);
780 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
781 KRL_DBG(("hash len %zu ", rb->len));
782 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
783 goto out;
784 }
785 if (sshbuf_len(sect) != 0) {
786 if ((r = sshbuf_put_u8(buf,
787 KRL_SECTION_FINGERPRINT_SHA1)) != 0 ||
788 (r = sshbuf_put_stringb(buf, sect)) != 0)
789 goto out;
790 }
791 sshbuf_reset(sect);
792 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) {
793 KRL_DBG(("hash len %zu ", rb->len));
794 if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
795 goto out;
796 }
797 if (sshbuf_len(sect) != 0) {
798 if ((r = sshbuf_put_u8(buf,
799 KRL_SECTION_FINGERPRINT_SHA256)) != 0 ||
800 (r = sshbuf_put_stringb(buf, sect)) != 0)
801 goto out;
802 }
803
804 for (i = 0; i < nsign_keys; i++) {
805 KRL_DBG(("sig key %s", sshkey_ssh_name(sign_keys[i])));
806 if ((r = sshbuf_put_u8(buf, KRL_SECTION_SIGNATURE)) != 0 ||
807 (r = sshkey_puts(sign_keys[i], buf)) != 0)
808 goto out;
809 /* XXX support sk-* keys */
810 if ((r = sshkey_sign(sign_keys[i], &sblob, &slen,
811 sshbuf_ptr(buf), sshbuf_len(buf), NULL, NULL,
812 NULL, 0)) != 0)
813 goto out;
814 KRL_DBG(("signature sig len %zu", slen));
815 if ((r = sshbuf_put_string(buf, sblob, slen)) != 0)
816 goto out;
817 }
818
819 r = 0;
820 out:
821 free(sblob);
822 sshbuf_free(sect);
823 return r;
824 }
825
826 static void
format_timestamp(u_int64_t timestamp,char * ts,size_t nts)827 format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
828 {
829 time_t t;
830 struct tm *tm;
831
832 t = timestamp;
833 tm = localtime(&t);
834 if (tm == NULL)
835 strlcpy(ts, "<INVALID>", nts);
836 else {
837 *ts = '\0';
838 strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
839 }
840 }
841
842 static int
parse_revoked_certs(struct sshbuf * buf,struct ssh_krl * krl)843 parse_revoked_certs(struct sshbuf *buf, struct ssh_krl *krl)
844 {
845 int r = SSH_ERR_INTERNAL_ERROR;
846 u_char type;
847 const u_char *blob;
848 size_t blen, nbits;
849 struct sshbuf *subsect = NULL;
850 u_int64_t serial, serial_lo, serial_hi;
851 struct bitmap *bitmap = NULL;
852 char *key_id = NULL;
853 struct sshkey *ca_key = NULL;
854
855 if ((subsect = sshbuf_new()) == NULL)
856 return SSH_ERR_ALLOC_FAIL;
857
858 /* Header: key, reserved */
859 if ((r = sshbuf_get_string_direct(buf, &blob, &blen)) != 0 ||
860 (r = sshbuf_skip_string(buf)) != 0)
861 goto out;
862 if (blen != 0 && (r = sshkey_from_blob(blob, blen, &ca_key)) != 0)
863 goto out;
864
865 while (sshbuf_len(buf) > 0) {
866 sshbuf_free(subsect);
867 subsect = NULL;
868 if ((r = sshbuf_get_u8(buf, &type)) != 0 ||
869 (r = sshbuf_froms(buf, &subsect)) != 0)
870 goto out;
871 KRL_DBG(("subsection type 0x%02x", type));
872 /* sshbuf_dump(subsect, stderr); */
873
874 switch (type) {
875 case KRL_SECTION_CERT_SERIAL_LIST:
876 while (sshbuf_len(subsect) > 0) {
877 if ((r = sshbuf_get_u64(subsect, &serial)) != 0)
878 goto out;
879 if ((r = ssh_krl_revoke_cert_by_serial(krl,
880 ca_key, serial)) != 0)
881 goto out;
882 }
883 break;
884 case KRL_SECTION_CERT_SERIAL_RANGE:
885 if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
886 (r = sshbuf_get_u64(subsect, &serial_hi)) != 0)
887 goto out;
888 if ((r = ssh_krl_revoke_cert_by_serial_range(krl,
889 ca_key, serial_lo, serial_hi)) != 0)
890 goto out;
891 break;
892 case KRL_SECTION_CERT_SERIAL_BITMAP:
893 if ((bitmap = bitmap_new()) == NULL) {
894 r = SSH_ERR_ALLOC_FAIL;
895 goto out;
896 }
897 if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
898 (r = sshbuf_get_bignum2_bytes_direct(subsect,
899 &blob, &blen)) != 0)
900 goto out;
901 if (bitmap_from_string(bitmap, blob, blen) != 0) {
902 r = SSH_ERR_INVALID_FORMAT;
903 goto out;
904 }
905 nbits = bitmap_nbits(bitmap);
906 for (serial = 0; serial < (u_int64_t)nbits; serial++) {
907 if (serial > 0 && serial_lo + serial == 0) {
908 error_f("bitmap wraps u64");
909 r = SSH_ERR_INVALID_FORMAT;
910 goto out;
911 }
912 if (!bitmap_test_bit(bitmap, serial))
913 continue;
914 if ((r = ssh_krl_revoke_cert_by_serial(krl,
915 ca_key, serial_lo + serial)) != 0)
916 goto out;
917 }
918 bitmap_free(bitmap);
919 bitmap = NULL;
920 break;
921 case KRL_SECTION_CERT_KEY_ID:
922 while (sshbuf_len(subsect) > 0) {
923 if ((r = sshbuf_get_cstring(subsect,
924 &key_id, NULL)) != 0)
925 goto out;
926 if ((r = ssh_krl_revoke_cert_by_key_id(krl,
927 ca_key, key_id)) != 0)
928 goto out;
929 free(key_id);
930 key_id = NULL;
931 }
932 break;
933 default:
934 error("Unsupported KRL certificate section %u", type);
935 r = SSH_ERR_INVALID_FORMAT;
936 goto out;
937 }
938 if (sshbuf_len(subsect) > 0) {
939 error("KRL certificate section contains unparsed data");
940 r = SSH_ERR_INVALID_FORMAT;
941 goto out;
942 }
943 }
944
945 r = 0;
946 out:
947 if (bitmap != NULL)
948 bitmap_free(bitmap);
949 free(key_id);
950 sshkey_free(ca_key);
951 sshbuf_free(subsect);
952 return r;
953 }
954
955 static int
blob_section(struct sshbuf * sect,struct revoked_blob_tree * target_tree,size_t expected_len)956 blob_section(struct sshbuf *sect, struct revoked_blob_tree *target_tree,
957 size_t expected_len)
958 {
959 u_char *rdata = NULL;
960 size_t rlen = 0;
961 int r;
962
963 while (sshbuf_len(sect) > 0) {
964 if ((r = sshbuf_get_string(sect, &rdata, &rlen)) != 0)
965 return r;
966 if (expected_len != 0 && rlen != expected_len) {
967 error_f("bad length");
968 free(rdata);
969 return SSH_ERR_INVALID_FORMAT;
970 }
971 if ((r = revoke_blob(target_tree, rdata, rlen)) != 0) {
972 free(rdata);
973 return r;
974 }
975 }
976 return 0;
977 }
978
979 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
980 int
ssh_krl_from_blob(struct sshbuf * buf,struct ssh_krl ** krlp,const struct sshkey ** sign_ca_keys,size_t nsign_ca_keys)981 ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
982 const struct sshkey **sign_ca_keys, size_t nsign_ca_keys)
983 {
984 struct sshbuf *copy = NULL, *sect = NULL;
985 struct ssh_krl *krl = NULL;
986 char timestamp[64];
987 int r = SSH_ERR_INTERNAL_ERROR, sig_seen;
988 struct sshkey *key = NULL, **ca_used = NULL, **tmp_ca_used;
989 u_char type;
990 const u_char *blob;
991 size_t i, j, sig_off, sects_off, blen, nca_used;
992 u_int format_version;
993
994 nca_used = 0;
995 *krlp = NULL;
996 if (sshbuf_len(buf) < sizeof(KRL_MAGIC) - 1 ||
997 memcmp(sshbuf_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
998 debug3_f("not a KRL");
999 return SSH_ERR_KRL_BAD_MAGIC;
1000 }
1001
1002 /* Take a copy of the KRL buffer so we can verify its signature later */
1003 if ((copy = sshbuf_fromb(buf)) == NULL) {
1004 r = SSH_ERR_ALLOC_FAIL;
1005 goto out;
1006 }
1007 if ((r = sshbuf_consume(copy, sizeof(KRL_MAGIC) - 1)) != 0)
1008 goto out;
1009
1010 if ((krl = ssh_krl_init()) == NULL) {
1011 error_f("alloc failed");
1012 goto out;
1013 }
1014
1015 if ((r = sshbuf_get_u32(copy, &format_version)) != 0)
1016 goto out;
1017 if (format_version != KRL_FORMAT_VERSION) {
1018 r = SSH_ERR_INVALID_FORMAT;
1019 goto out;
1020 }
1021 if ((r = sshbuf_get_u64(copy, &krl->krl_version)) != 0 ||
1022 (r = sshbuf_get_u64(copy, &krl->generated_date)) != 0 ||
1023 (r = sshbuf_get_u64(copy, &krl->flags)) != 0 ||
1024 (r = sshbuf_skip_string(copy)) != 0 ||
1025 (r = sshbuf_get_cstring(copy, &krl->comment, NULL)) != 0)
1026 goto out;
1027
1028 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1029 debug("KRL version %llu generated at %s%s%s",
1030 (long long unsigned)krl->krl_version, timestamp,
1031 *krl->comment ? ": " : "", krl->comment);
1032
1033 /*
1034 * 1st pass: verify signatures, if any. This is done to avoid
1035 * detailed parsing of data whose provenance is unverified.
1036 */
1037 sig_seen = 0;
1038 if (sshbuf_len(buf) < sshbuf_len(copy)) {
1039 /* Shouldn't happen */
1040 r = SSH_ERR_INTERNAL_ERROR;
1041 goto out;
1042 }
1043 sects_off = sshbuf_len(buf) - sshbuf_len(copy);
1044 while (sshbuf_len(copy) > 0) {
1045 if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1046 (r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0)
1047 goto out;
1048 KRL_DBG(("first pass, section 0x%02x", type));
1049 if (type != KRL_SECTION_SIGNATURE) {
1050 if (sig_seen) {
1051 error("KRL contains non-signature section "
1052 "after signature");
1053 r = SSH_ERR_INVALID_FORMAT;
1054 goto out;
1055 }
1056 /* Not interested for now. */
1057 continue;
1058 }
1059 sig_seen = 1;
1060 /* First string component is the signing key */
1061 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
1062 r = SSH_ERR_INVALID_FORMAT;
1063 goto out;
1064 }
1065 if (sshbuf_len(buf) < sshbuf_len(copy)) {
1066 /* Shouldn't happen */
1067 r = SSH_ERR_INTERNAL_ERROR;
1068 goto out;
1069 }
1070 sig_off = sshbuf_len(buf) - sshbuf_len(copy);
1071 /* Second string component is the signature itself */
1072 if ((r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0) {
1073 r = SSH_ERR_INVALID_FORMAT;
1074 goto out;
1075 }
1076 /* Check signature over entire KRL up to this point */
1077 if ((r = sshkey_verify(key, blob, blen,
1078 sshbuf_ptr(buf), sig_off, NULL, 0, NULL)) != 0)
1079 goto out;
1080 /* Check if this key has already signed this KRL */
1081 for (i = 0; i < nca_used; i++) {
1082 if (sshkey_equal(ca_used[i], key)) {
1083 error("KRL signed more than once with "
1084 "the same key");
1085 r = SSH_ERR_INVALID_FORMAT;
1086 goto out;
1087 }
1088 }
1089 /* Record keys used to sign the KRL */
1090 tmp_ca_used = recallocarray(ca_used, nca_used, nca_used + 1,
1091 sizeof(*ca_used));
1092 if (tmp_ca_used == NULL) {
1093 r = SSH_ERR_ALLOC_FAIL;
1094 goto out;
1095 }
1096 ca_used = tmp_ca_used;
1097 ca_used[nca_used++] = key;
1098 key = NULL;
1099 }
1100
1101 if (sshbuf_len(copy) != 0) {
1102 /* Shouldn't happen */
1103 r = SSH_ERR_INTERNAL_ERROR;
1104 goto out;
1105 }
1106
1107 /*
1108 * 2nd pass: parse and load the KRL, skipping the header to the point
1109 * where the section start.
1110 */
1111 sshbuf_free(copy);
1112 if ((copy = sshbuf_fromb(buf)) == NULL) {
1113 r = SSH_ERR_ALLOC_FAIL;
1114 goto out;
1115 }
1116 if ((r = sshbuf_consume(copy, sects_off)) != 0)
1117 goto out;
1118 while (sshbuf_len(copy) > 0) {
1119 sshbuf_free(sect);
1120 sect = NULL;
1121 if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1122 (r = sshbuf_froms(copy, §)) != 0)
1123 goto out;
1124 KRL_DBG(("second pass, section 0x%02x", type));
1125
1126 switch (type) {
1127 case KRL_SECTION_CERTIFICATES:
1128 if ((r = parse_revoked_certs(sect, krl)) != 0)
1129 goto out;
1130 break;
1131 case KRL_SECTION_EXPLICIT_KEY:
1132 if ((r = blob_section(sect,
1133 &krl->revoked_keys, 0)) != 0)
1134 goto out;
1135 break;
1136 case KRL_SECTION_FINGERPRINT_SHA1:
1137 if ((r = blob_section(sect,
1138 &krl->revoked_sha1s, 20)) != 0)
1139 goto out;
1140 break;
1141 case KRL_SECTION_FINGERPRINT_SHA256:
1142 if ((r = blob_section(sect,
1143 &krl->revoked_sha256s, 32)) != 0)
1144 goto out;
1145 break;
1146 case KRL_SECTION_SIGNATURE:
1147 /* Handled above, but still need to stay in synch */
1148 sshbuf_free(sect);
1149 sect = NULL;
1150 if ((r = sshbuf_skip_string(copy)) != 0)
1151 goto out;
1152 break;
1153 default:
1154 error("Unsupported KRL section %u", type);
1155 r = SSH_ERR_INVALID_FORMAT;
1156 goto out;
1157 }
1158 if (sect != NULL && sshbuf_len(sect) > 0) {
1159 error("KRL section contains unparsed data");
1160 r = SSH_ERR_INVALID_FORMAT;
1161 goto out;
1162 }
1163 }
1164
1165 /* Check that the key(s) used to sign the KRL weren't revoked */
1166 sig_seen = 0;
1167 for (i = 0; i < nca_used; i++) {
1168 if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1169 sig_seen = 1;
1170 else {
1171 sshkey_free(ca_used[i]);
1172 ca_used[i] = NULL;
1173 }
1174 }
1175 if (nca_used && !sig_seen) {
1176 error("All keys used to sign KRL were revoked");
1177 r = SSH_ERR_KEY_REVOKED;
1178 goto out;
1179 }
1180
1181 /* If we have CA keys, then verify that one was used to sign the KRL */
1182 if (sig_seen && nsign_ca_keys != 0) {
1183 sig_seen = 0;
1184 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1185 for (j = 0; j < nca_used; j++) {
1186 if (ca_used[j] == NULL)
1187 continue;
1188 if (sshkey_equal(ca_used[j], sign_ca_keys[i])) {
1189 sig_seen = 1;
1190 break;
1191 }
1192 }
1193 }
1194 if (!sig_seen) {
1195 r = SSH_ERR_SIGNATURE_INVALID;
1196 error("KRL not signed with any trusted key");
1197 goto out;
1198 }
1199 }
1200
1201 *krlp = krl;
1202 r = 0;
1203 out:
1204 if (r != 0)
1205 ssh_krl_free(krl);
1206 for (i = 0; i < nca_used; i++)
1207 sshkey_free(ca_used[i]);
1208 free(ca_used);
1209 sshkey_free(key);
1210 sshbuf_free(copy);
1211 sshbuf_free(sect);
1212 return r;
1213 }
1214
1215 /* Checks certificate serial number and key ID revocation */
1216 static int
is_cert_revoked(const struct sshkey * key,struct revoked_certs * rc)1217 is_cert_revoked(const struct sshkey *key, struct revoked_certs *rc)
1218 {
1219 struct revoked_serial rs, *ers;
1220 struct revoked_key_id rki, *erki;
1221
1222 /* Check revocation by cert key ID */
1223 memset(&rki, 0, sizeof(rki));
1224 rki.key_id = key->cert->key_id;
1225 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1226 if (erki != NULL) {
1227 KRL_DBG(("revoked by key ID"));
1228 return SSH_ERR_KEY_REVOKED;
1229 }
1230
1231 /*
1232 * Zero serials numbers are ignored (it's the default when the
1233 * CA doesn't specify one).
1234 */
1235 if (key->cert->serial == 0)
1236 return 0;
1237
1238 memset(&rs, 0, sizeof(rs));
1239 rs.lo = rs.hi = key->cert->serial;
1240 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1241 if (ers != NULL) {
1242 KRL_DBG(("revoked serial %llu matched %llu:%llu",
1243 key->cert->serial, ers->lo, ers->hi));
1244 return SSH_ERR_KEY_REVOKED;
1245 }
1246 return 0;
1247 }
1248
1249 /* Checks whether a given key/cert is revoked. Does not check its CA */
1250 static int
is_key_revoked(struct ssh_krl * krl,const struct sshkey * key)1251 is_key_revoked(struct ssh_krl *krl, const struct sshkey *key)
1252 {
1253 struct revoked_blob rb, *erb;
1254 struct revoked_certs *rc;
1255 int r;
1256
1257 /* Check explicitly revoked hashes first */
1258 memset(&rb, 0, sizeof(rb));
1259 if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA1,
1260 &rb.blob, &rb.len)) != 0)
1261 return r;
1262 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1263 free(rb.blob);
1264 if (erb != NULL) {
1265 KRL_DBG(("revoked by key SHA1"));
1266 return SSH_ERR_KEY_REVOKED;
1267 }
1268 memset(&rb, 0, sizeof(rb));
1269 if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA256,
1270 &rb.blob, &rb.len)) != 0)
1271 return r;
1272 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha256s, &rb);
1273 free(rb.blob);
1274 if (erb != NULL) {
1275 KRL_DBG(("revoked by key SHA256"));
1276 return SSH_ERR_KEY_REVOKED;
1277 }
1278
1279 /* Next, explicit keys */
1280 memset(&rb, 0, sizeof(rb));
1281 if ((r = plain_key_blob(key, &rb.blob, &rb.len)) != 0)
1282 return r;
1283 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1284 free(rb.blob);
1285 if (erb != NULL) {
1286 KRL_DBG(("revoked by explicit key"));
1287 return SSH_ERR_KEY_REVOKED;
1288 }
1289
1290 if (!sshkey_is_cert(key))
1291 return 0;
1292
1293 /* Check cert revocation for the specified CA */
1294 if ((r = revoked_certs_for_ca_key(krl, key->cert->signature_key,
1295 &rc, 0)) != 0)
1296 return r;
1297 if (rc != NULL) {
1298 if ((r = is_cert_revoked(key, rc)) != 0)
1299 return r;
1300 }
1301 /* Check cert revocation for the wildcard CA */
1302 if ((r = revoked_certs_for_ca_key(krl, NULL, &rc, 0)) != 0)
1303 return r;
1304 if (rc != NULL) {
1305 if ((r = is_cert_revoked(key, rc)) != 0)
1306 return r;
1307 }
1308
1309 KRL_DBG(("%llu no match", key->cert->serial));
1310 return 0;
1311 }
1312
1313 int
ssh_krl_check_key(struct ssh_krl * krl,const struct sshkey * key)1314 ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key)
1315 {
1316 int r;
1317
1318 KRL_DBG(("checking key"));
1319 if ((r = is_key_revoked(krl, key)) != 0)
1320 return r;
1321 if (sshkey_is_cert(key)) {
1322 debug2_f("checking CA key");
1323 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1324 return r;
1325 }
1326 KRL_DBG(("key okay"));
1327 return 0;
1328 }
1329
1330 int
ssh_krl_file_contains_key(const char * path,const struct sshkey * key)1331 ssh_krl_file_contains_key(const char *path, const struct sshkey *key)
1332 {
1333 struct sshbuf *krlbuf = NULL;
1334 struct ssh_krl *krl = NULL;
1335 int oerrno = 0, r;
1336
1337 if (path == NULL)
1338 return 0;
1339 if ((r = sshbuf_load_file(path, &krlbuf)) != 0) {
1340 oerrno = errno;
1341 goto out;
1342 }
1343 if ((r = ssh_krl_from_blob(krlbuf, &krl, NULL, 0)) != 0)
1344 goto out;
1345 debug2_f("checking KRL %s", path);
1346 r = ssh_krl_check_key(krl, key);
1347 out:
1348 sshbuf_free(krlbuf);
1349 ssh_krl_free(krl);
1350 if (r != 0)
1351 errno = oerrno;
1352 return r;
1353 }
1354
1355 int
krl_dump(struct ssh_krl * krl,FILE * f)1356 krl_dump(struct ssh_krl *krl, FILE *f)
1357 {
1358 struct sshkey *key = NULL;
1359 struct revoked_blob *rb;
1360 struct revoked_certs *rc;
1361 struct revoked_serial *rs;
1362 struct revoked_key_id *rki;
1363 int r, ret = 0;
1364 char *fp, timestamp[64];
1365
1366 /* Try to print in a KRL spec-compatible format */
1367 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1368 fprintf(f, "# KRL version %llu\n",
1369 (unsigned long long)krl->krl_version);
1370 fprintf(f, "# Generated at %s\n", timestamp);
1371 if (krl->comment != NULL && *krl->comment != '\0') {
1372 r = INT_MAX;
1373 asmprintf(&fp, INT_MAX, &r, "%s", krl->comment);
1374 fprintf(f, "# Comment: %s\n", fp);
1375 free(fp);
1376 }
1377 fputc('\n', f);
1378
1379 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
1380 if ((r = sshkey_from_blob(rb->blob, rb->len, &key)) != 0) {
1381 ret = SSH_ERR_INVALID_FORMAT;
1382 error_r(r, "parse KRL key");
1383 continue;
1384 }
1385 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
1386 SSH_FP_DEFAULT)) == NULL) {
1387 ret = SSH_ERR_INVALID_FORMAT;
1388 error("sshkey_fingerprint failed");
1389 continue;
1390 }
1391 fprintf(f, "hash: %s # %s\n", fp, sshkey_ssh_name(key));
1392 free(fp);
1393 free(key);
1394 }
1395 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) {
1396 fp = tohex(rb->blob, rb->len);
1397 fprintf(f, "hash: SHA256:%s\n", fp);
1398 free(fp);
1399 }
1400 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
1401 /*
1402 * There is not KRL spec keyword for raw SHA1 hashes, so
1403 * print them as comments.
1404 */
1405 fp = tohex(rb->blob, rb->len);
1406 fprintf(f, "# hash SHA1:%s\n", fp);
1407 free(fp);
1408 }
1409
1410 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
1411 fputc('\n', f);
1412 if (rc->ca_key == NULL)
1413 fprintf(f, "# Wildcard CA\n");
1414 else {
1415 if ((fp = sshkey_fingerprint(rc->ca_key,
1416 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) {
1417 ret = SSH_ERR_INVALID_FORMAT;
1418 error("sshkey_fingerprint failed");
1419 continue;
1420 }
1421 fprintf(f, "# CA key %s %s\n",
1422 sshkey_ssh_name(rc->ca_key), fp);
1423 free(fp);
1424 }
1425 RB_FOREACH(rs, revoked_serial_tree, &rc->revoked_serials) {
1426 if (rs->lo == rs->hi) {
1427 fprintf(f, "serial: %llu\n",
1428 (unsigned long long)rs->lo);
1429 } else {
1430 fprintf(f, "serial: %llu-%llu\n",
1431 (unsigned long long)rs->lo,
1432 (unsigned long long)rs->hi);
1433 }
1434 }
1435 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
1436 /*
1437 * We don't want key IDs with embedded newlines to
1438 * mess up the display.
1439 */
1440 r = INT_MAX;
1441 asmprintf(&fp, INT_MAX, &r, "%s", rki->key_id);
1442 fprintf(f, "id: %s\n", fp);
1443 free(fp);
1444 }
1445 }
1446 return ret;
1447 }
1448