xref: /openssh-portable/krl.c (revision 4f7a56d5)
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 1.43 2019/06/21 04:21:04 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 <string.h>
29 #include <time.h>
30 #include <unistd.h>
31 
32 #include "sshbuf.h"
33 #include "ssherr.h"
34 #include "sshkey.h"
35 #include "authfile.h"
36 #include "misc.h"
37 #include "log.h"
38 #include "digest.h"
39 #include "bitmap.h"
40 
41 #include "krl.h"
42 
43 /* #define DEBUG_KRL */
44 #ifdef DEBUG_KRL
45 # define KRL_DBG(x) debug3 x
46 #else
47 # define KRL_DBG(x)
48 #endif
49 
50 /*
51  * Trees of revoked serial numbers, key IDs and keys. This allows
52  * quick searching, querying and producing lists in canonical order.
53  */
54 
55 /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */
56 struct revoked_serial {
57 	u_int64_t lo, hi;
58 	RB_ENTRY(revoked_serial) tree_entry;
59 };
60 static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b);
61 RB_HEAD(revoked_serial_tree, revoked_serial);
62 RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp);
63 
64 /* Tree of key IDs */
65 struct revoked_key_id {
66 	char *key_id;
67 	RB_ENTRY(revoked_key_id) tree_entry;
68 };
69 static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b);
70 RB_HEAD(revoked_key_id_tree, revoked_key_id);
71 RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp);
72 
73 /* Tree of blobs (used for keys and fingerprints) */
74 struct revoked_blob {
75 	u_char *blob;
76 	size_t len;
77 	RB_ENTRY(revoked_blob) tree_entry;
78 };
79 static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b);
80 RB_HEAD(revoked_blob_tree, revoked_blob);
81 RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp);
82 
83 /* Tracks revoked certs for a single CA */
84 struct revoked_certs {
85 	struct sshkey *ca_key;
86 	struct revoked_serial_tree revoked_serials;
87 	struct revoked_key_id_tree revoked_key_ids;
88 	TAILQ_ENTRY(revoked_certs) entry;
89 };
90 TAILQ_HEAD(revoked_certs_list, revoked_certs);
91 
92 struct ssh_krl {
93 	u_int64_t krl_version;
94 	u_int64_t generated_date;
95 	u_int64_t flags;
96 	char *comment;
97 	struct revoked_blob_tree revoked_keys;
98 	struct revoked_blob_tree revoked_sha1s;
99 	struct revoked_blob_tree revoked_sha256s;
100 	struct revoked_certs_list revoked_certs;
101 };
102 
103 /* Return equal if a and b overlap */
104 static int
serial_cmp(struct revoked_serial * a,struct revoked_serial * b)105 serial_cmp(struct revoked_serial *a, struct revoked_serial *b)
106 {
107 	if (a->hi >= b->lo && a->lo <= b->hi)
108 		return 0;
109 	return a->lo < b->lo ? -1 : 1;
110 }
111 
112 static int
key_id_cmp(struct revoked_key_id * a,struct revoked_key_id * b)113 key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b)
114 {
115 	return strcmp(a->key_id, b->key_id);
116 }
117 
118 static int
blob_cmp(struct revoked_blob * a,struct revoked_blob * b)119 blob_cmp(struct revoked_blob *a, struct revoked_blob *b)
120 {
121 	int r;
122 
123 	if (a->len != b->len) {
124 		if ((r = memcmp(a->blob, b->blob, MINIMUM(a->len, b->len))) != 0)
125 			return r;
126 		return a->len > b->len ? 1 : -1;
127 	} else
128 		return memcmp(a->blob, b->blob, a->len);
129 }
130 
131 struct ssh_krl *
ssh_krl_init(void)132 ssh_krl_init(void)
133 {
134 	struct ssh_krl *krl;
135 
136 	if ((krl = calloc(1, sizeof(*krl))) == NULL)
137 		return NULL;
138 	RB_INIT(&krl->revoked_keys);
139 	RB_INIT(&krl->revoked_sha1s);
140 	RB_INIT(&krl->revoked_sha256s);
141 	TAILQ_INIT(&krl->revoked_certs);
142 	return krl;
143 }
144 
145 static void
revoked_certs_free(struct revoked_certs * rc)146 revoked_certs_free(struct revoked_certs *rc)
147 {
148 	struct revoked_serial *rs, *trs;
149 	struct revoked_key_id *rki, *trki;
150 
151 	RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) {
152 		RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs);
153 		free(rs);
154 	}
155 	RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) {
156 		RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki);
157 		free(rki->key_id);
158 		free(rki);
159 	}
160 	sshkey_free(rc->ca_key);
161 }
162 
163 void
ssh_krl_free(struct ssh_krl * krl)164 ssh_krl_free(struct ssh_krl *krl)
165 {
166 	struct revoked_blob *rb, *trb;
167 	struct revoked_certs *rc, *trc;
168 
169 	if (krl == NULL)
170 		return;
171 
172 	free(krl->comment);
173 	RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) {
174 		RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb);
175 		free(rb->blob);
176 		free(rb);
177 	}
178 	RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) {
179 		RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb);
180 		free(rb->blob);
181 		free(rb);
182 	}
183 	RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha256s, trb) {
184 		RB_REMOVE(revoked_blob_tree, &krl->revoked_sha256s, rb);
185 		free(rb->blob);
186 		free(rb);
187 	}
188 	TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) {
189 		TAILQ_REMOVE(&krl->revoked_certs, rc, entry);
190 		revoked_certs_free(rc);
191 	}
192 }
193 
194 void
ssh_krl_set_version(struct ssh_krl * krl,u_int64_t version)195 ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version)
196 {
197 	krl->krl_version = version;
198 }
199 
200 int
ssh_krl_set_comment(struct ssh_krl * krl,const char * comment)201 ssh_krl_set_comment(struct ssh_krl *krl, const char *comment)
202 {
203 	free(krl->comment);
204 	if ((krl->comment = strdup(comment)) == NULL)
205 		return SSH_ERR_ALLOC_FAIL;
206 	return 0;
207 }
208 
209 /*
210  * Find the revoked_certs struct for a CA key. If allow_create is set then
211  * create a new one in the tree if one did not exist already.
212  */
213 static int
revoked_certs_for_ca_key(struct ssh_krl * krl,const struct sshkey * ca_key,struct revoked_certs ** rcp,int allow_create)214 revoked_certs_for_ca_key(struct ssh_krl *krl, const struct sshkey *ca_key,
215     struct revoked_certs **rcp, int allow_create)
216 {
217 	struct revoked_certs *rc;
218 	int r;
219 
220 	*rcp = NULL;
221 	TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
222 		if ((ca_key == NULL && rc->ca_key == NULL) ||
223 		    sshkey_equal(rc->ca_key, ca_key)) {
224 			*rcp = rc;
225 			return 0;
226 		}
227 	}
228 	if (!allow_create)
229 		return 0;
230 	/* If this CA doesn't exist in the list then add it now */
231 	if ((rc = calloc(1, sizeof(*rc))) == NULL)
232 		return SSH_ERR_ALLOC_FAIL;
233 	if (ca_key == NULL)
234 		rc->ca_key = NULL;
235 	else if ((r = sshkey_from_private(ca_key, &rc->ca_key)) != 0) {
236 		free(rc);
237 		return r;
238 	}
239 	RB_INIT(&rc->revoked_serials);
240 	RB_INIT(&rc->revoked_key_ids);
241 	TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry);
242 	KRL_DBG(("%s: new CA %s", __func__,
243 	    ca_key == NULL ? "*" : sshkey_type(ca_key)));
244 	*rcp = rc;
245 	return 0;
246 }
247 
248 static int
insert_serial_range(struct revoked_serial_tree * rt,u_int64_t lo,u_int64_t hi)249 insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi)
250 {
251 	struct revoked_serial rs, *ers, *crs, *irs;
252 
253 	KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi));
254 	memset(&rs, 0, sizeof(rs));
255 	rs.lo = lo;
256 	rs.hi = hi;
257 	ers = RB_NFIND(revoked_serial_tree, rt, &rs);
258 	if (ers == NULL || serial_cmp(ers, &rs) != 0) {
259 		/* No entry matches. Just insert */
260 		if ((irs = malloc(sizeof(rs))) == NULL)
261 			return SSH_ERR_ALLOC_FAIL;
262 		memcpy(irs, &rs, sizeof(*irs));
263 		ers = RB_INSERT(revoked_serial_tree, rt, irs);
264 		if (ers != NULL) {
265 			KRL_DBG(("%s: bad: ers != NULL", __func__));
266 			/* Shouldn't happen */
267 			free(irs);
268 			return SSH_ERR_INTERNAL_ERROR;
269 		}
270 		ers = irs;
271 	} else {
272 		KRL_DBG(("%s: overlap found %llu:%llu", __func__,
273 		    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(("%s: pred %llu:%llu", __func__, 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(("%s: pred extend %llu:%llu", __func__,
298 			    ers->lo, ers->hi));
299 		}
300 		RB_REMOVE(revoked_serial_tree, rt, crs);
301 		free(crs);
302 	}
303 	/* Check successors */
304 	while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) {
305 		KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi));
306 		if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1)
307 			break;
308 		/* This entry overlaps. */
309 		if (crs->hi > ers->hi) {
310 			ers->hi = crs->hi;
311 			KRL_DBG(("%s: succ extend %llu:%llu", __func__,
312 			    ers->lo, ers->hi));
313 		}
314 		RB_REMOVE(revoked_serial_tree, rt, crs);
315 		free(crs);
316 	}
317 	KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi));
318 	return 0;
319 }
320 
321 int
ssh_krl_revoke_cert_by_serial(struct ssh_krl * krl,const struct sshkey * ca_key,u_int64_t serial)322 ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const struct sshkey *ca_key,
323     u_int64_t serial)
324 {
325 	return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial);
326 }
327 
328 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)329 ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl,
330     const struct sshkey *ca_key, u_int64_t lo, u_int64_t hi)
331 {
332 	struct revoked_certs *rc;
333 	int r;
334 
335 	if (lo > hi || lo == 0)
336 		return SSH_ERR_INVALID_ARGUMENT;
337 	if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
338 		return r;
339 	return insert_serial_range(&rc->revoked_serials, lo, hi);
340 }
341 
342 int
ssh_krl_revoke_cert_by_key_id(struct ssh_krl * krl,const struct sshkey * ca_key,const char * key_id)343 ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const struct sshkey *ca_key,
344     const char *key_id)
345 {
346 	struct revoked_key_id *rki, *erki;
347 	struct revoked_certs *rc;
348 	int r;
349 
350 	if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0)
351 		return r;
352 
353 	KRL_DBG(("%s: revoke %s", __func__, key_id));
354 	if ((rki = calloc(1, sizeof(*rki))) == NULL ||
355 	    (rki->key_id = strdup(key_id)) == NULL) {
356 		free(rki);
357 		return SSH_ERR_ALLOC_FAIL;
358 	}
359 	erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki);
360 	if (erki != NULL) {
361 		free(rki->key_id);
362 		free(rki);
363 	}
364 	return 0;
365 }
366 
367 /* Convert "key" to a public key blob without any certificate information */
368 static int
plain_key_blob(const struct sshkey * key,u_char ** blob,size_t * blen)369 plain_key_blob(const struct sshkey *key, u_char **blob, size_t *blen)
370 {
371 	struct sshkey *kcopy;
372 	int r;
373 
374 	if ((r = sshkey_from_private(key, &kcopy)) != 0)
375 		return r;
376 	if (sshkey_is_cert(kcopy)) {
377 		if ((r = sshkey_drop_cert(kcopy)) != 0) {
378 			sshkey_free(kcopy);
379 			return r;
380 		}
381 	}
382 	r = sshkey_to_blob(kcopy, blob, blen);
383 	sshkey_free(kcopy);
384 	return r;
385 }
386 
387 /* Revoke a key blob. Ownership of blob is transferred to the tree */
388 static int
revoke_blob(struct revoked_blob_tree * rbt,u_char * blob,size_t len)389 revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, size_t len)
390 {
391 	struct revoked_blob *rb, *erb;
392 
393 	if ((rb = calloc(1, sizeof(*rb))) == NULL)
394 		return SSH_ERR_ALLOC_FAIL;
395 	rb->blob = blob;
396 	rb->len = len;
397 	erb = RB_INSERT(revoked_blob_tree, rbt, rb);
398 	if (erb != NULL) {
399 		free(rb->blob);
400 		free(rb);
401 	}
402 	return 0;
403 }
404 
405 int
ssh_krl_revoke_key_explicit(struct ssh_krl * krl,const struct sshkey * key)406 ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const struct sshkey *key)
407 {
408 	u_char *blob;
409 	size_t len;
410 	int r;
411 
412 	debug3("%s: revoke type %s", __func__, sshkey_type(key));
413 	if ((r = plain_key_blob(key, &blob, &len)) != 0)
414 		return r;
415 	return revoke_blob(&krl->revoked_keys, blob, len);
416 }
417 
418 static int
revoke_by_hash(struct revoked_blob_tree * target,const u_char * p,size_t len)419 revoke_by_hash(struct revoked_blob_tree *target, const u_char *p, size_t len)
420 {
421 	u_char *blob;
422 	int r;
423 
424 	/* need to copy hash, as revoke_blob steals ownership */
425 	if ((blob = malloc(len)) == NULL)
426 		return SSH_ERR_SYSTEM_ERROR;
427 	memcpy(blob, p, len);
428 	if ((r = revoke_blob(target, blob, len)) != 0) {
429 		free(blob);
430 		return r;
431 	}
432 	return 0;
433 }
434 
435 int
ssh_krl_revoke_key_sha1(struct ssh_krl * krl,const u_char * p,size_t len)436 ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const u_char *p, size_t len)
437 {
438 	debug3("%s: revoke by sha1", __func__);
439 	if (len != 20)
440 		return SSH_ERR_INVALID_FORMAT;
441 	return revoke_by_hash(&krl->revoked_sha1s, p, len);
442 }
443 
444 int
ssh_krl_revoke_key_sha256(struct ssh_krl * krl,const u_char * p,size_t len)445 ssh_krl_revoke_key_sha256(struct ssh_krl *krl, const u_char *p, size_t len)
446 {
447 	debug3("%s: revoke by sha256", __func__);
448 	if (len != 32)
449 		return SSH_ERR_INVALID_FORMAT;
450 	return revoke_by_hash(&krl->revoked_sha256s, p, len);
451 }
452 
453 int
ssh_krl_revoke_key(struct ssh_krl * krl,const struct sshkey * key)454 ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key)
455 {
456 	/* XXX replace with SHA256? */
457 	if (!sshkey_is_cert(key))
458 		return ssh_krl_revoke_key_explicit(krl, key);
459 
460 	if (key->cert->serial == 0) {
461 		return ssh_krl_revoke_cert_by_key_id(krl,
462 		    key->cert->signature_key,
463 		    key->cert->key_id);
464 	} else {
465 		return ssh_krl_revoke_cert_by_serial(krl,
466 		    key->cert->signature_key,
467 		    key->cert->serial);
468 	}
469 }
470 
471 /*
472  * Select the most compact section type to emit next in a KRL based on
473  * the current section type, the run length of contiguous revoked serial
474  * numbers and the gaps from the last and to the next revoked serial.
475  * Applies a mostly-accurate bit cost model to select the section type
476  * that will minimise the size of the resultant KRL.
477  */
478 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)479 choose_next_state(int current_state, u_int64_t contig, int final,
480     u_int64_t last_gap, u_int64_t next_gap, int *force_new_section)
481 {
482 	int new_state;
483 	u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart;
484 
485 	/*
486 	 * Avoid unsigned overflows.
487 	 * The limits are high enough to avoid confusing the calculations.
488 	 */
489 	contig = MINIMUM(contig, 1ULL<<31);
490 	last_gap = MINIMUM(last_gap, 1ULL<<31);
491 	next_gap = MINIMUM(next_gap, 1ULL<<31);
492 
493 	/*
494 	 * Calculate the cost to switch from the current state to candidates.
495 	 * NB. range sections only ever contain a single range, so their
496 	 * switching cost is independent of the current_state.
497 	 */
498 	cost_list = cost_bitmap = cost_bitmap_restart = 0;
499 	cost_range = 8;
500 	switch (current_state) {
501 	case KRL_SECTION_CERT_SERIAL_LIST:
502 		cost_bitmap_restart = cost_bitmap = 8 + 64;
503 		break;
504 	case KRL_SECTION_CERT_SERIAL_BITMAP:
505 		cost_list = 8;
506 		cost_bitmap_restart = 8 + 64;
507 		break;
508 	case KRL_SECTION_CERT_SERIAL_RANGE:
509 	case 0:
510 		cost_bitmap_restart = cost_bitmap = 8 + 64;
511 		cost_list = 8;
512 	}
513 
514 	/* Estimate base cost in bits of each section type */
515 	cost_list += 64 * contig + (final ? 0 : 8+64);
516 	cost_range += (2 * 64) + (final ? 0 : 8+64);
517 	cost_bitmap += last_gap + contig + (final ? 0 : MINIMUM(next_gap, 8+64));
518 	cost_bitmap_restart += contig + (final ? 0 : MINIMUM(next_gap, 8+64));
519 
520 	/* Convert to byte costs for actual comparison */
521 	cost_list = (cost_list + 7) / 8;
522 	cost_bitmap = (cost_bitmap + 7) / 8;
523 	cost_bitmap_restart = (cost_bitmap_restart + 7) / 8;
524 	cost_range = (cost_range + 7) / 8;
525 
526 	/* Now pick the best choice */
527 	*force_new_section = 0;
528 	new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
529 	cost = cost_bitmap;
530 	if (cost_range < cost) {
531 		new_state = KRL_SECTION_CERT_SERIAL_RANGE;
532 		cost = cost_range;
533 	}
534 	if (cost_list < cost) {
535 		new_state = KRL_SECTION_CERT_SERIAL_LIST;
536 		cost = cost_list;
537 	}
538 	if (cost_bitmap_restart < cost) {
539 		new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
540 		*force_new_section = 1;
541 		cost = cost_bitmap_restart;
542 	}
543 	KRL_DBG(("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:"
544 	    "list %llu range %llu bitmap %llu new bitmap %llu, "
545 	    "selected 0x%02x%s", __func__, (long long unsigned)contig,
546 	    (long long unsigned)last_gap, (long long unsigned)next_gap, final,
547 	    (long long unsigned)cost_list, (long long unsigned)cost_range,
548 	    (long long unsigned)cost_bitmap,
549 	    (long long unsigned)cost_bitmap_restart, new_state,
550 	    *force_new_section ? " restart" : ""));
551 	return new_state;
552 }
553 
554 static int
put_bitmap(struct sshbuf * buf,struct bitmap * bitmap)555 put_bitmap(struct sshbuf *buf, struct bitmap *bitmap)
556 {
557 	size_t len;
558 	u_char *blob;
559 	int r;
560 
561 	len = bitmap_nbytes(bitmap);
562 	if ((blob = malloc(len)) == NULL)
563 		return SSH_ERR_ALLOC_FAIL;
564 	if (bitmap_to_string(bitmap, blob, len) != 0) {
565 		free(blob);
566 		return SSH_ERR_INTERNAL_ERROR;
567 	}
568 	r = sshbuf_put_bignum2_bytes(buf, blob, len);
569 	free(blob);
570 	return r;
571 }
572 
573 /* Generate a KRL_SECTION_CERTIFICATES KRL section */
574 static int
revoked_certs_generate(struct revoked_certs * rc,struct sshbuf * buf)575 revoked_certs_generate(struct revoked_certs *rc, struct sshbuf *buf)
576 {
577 	int final, force_new_sect, r = SSH_ERR_INTERNAL_ERROR;
578 	u_int64_t i, contig, gap, last = 0, bitmap_start = 0;
579 	struct revoked_serial *rs, *nrs;
580 	struct revoked_key_id *rki;
581 	int next_state, state = 0;
582 	struct sshbuf *sect;
583 	struct bitmap *bitmap = NULL;
584 
585 	if ((sect = sshbuf_new()) == NULL)
586 		return SSH_ERR_ALLOC_FAIL;
587 
588 	/* Store the header: optional CA scope key, reserved */
589 	if (rc->ca_key == NULL) {
590 		if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
591 			goto out;
592 	} else {
593 		if ((r = sshkey_puts(rc->ca_key, buf)) != 0)
594 			goto out;
595 	}
596 	if ((r = sshbuf_put_string(buf, NULL, 0)) != 0)
597 		goto out;
598 
599 	/* Store the revoked serials.  */
600 	for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials);
601 	     rs != NULL;
602 	     rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) {
603 		KRL_DBG(("%s: serial %llu:%llu state 0x%02x", __func__,
604 		    (long long unsigned)rs->lo, (long long unsigned)rs->hi,
605 		    state));
606 
607 		/* Check contiguous length and gap to next section (if any) */
608 		nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
609 		final = nrs == NULL;
610 		gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
611 		contig = 1 + (rs->hi - rs->lo);
612 
613 		/* Choose next state based on these */
614 		next_state = choose_next_state(state, contig, final,
615 		    state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
616 
617 		/*
618 		 * If the current section is a range section or has a different
619 		 * type to the next section, then finish it off now.
620 		 */
621 		if (state != 0 && (force_new_sect || next_state != state ||
622 		    state == KRL_SECTION_CERT_SERIAL_RANGE)) {
623 			KRL_DBG(("%s: finish state 0x%02x", __func__, state));
624 			switch (state) {
625 			case KRL_SECTION_CERT_SERIAL_LIST:
626 			case KRL_SECTION_CERT_SERIAL_RANGE:
627 				break;
628 			case KRL_SECTION_CERT_SERIAL_BITMAP:
629 				if ((r = put_bitmap(sect, bitmap)) != 0)
630 					goto out;
631 				bitmap_free(bitmap);
632 				bitmap = NULL;
633 				break;
634 			}
635 			if ((r = sshbuf_put_u8(buf, state)) != 0 ||
636 			    (r = sshbuf_put_stringb(buf, sect)) != 0)
637 				goto out;
638 			sshbuf_reset(sect);
639 		}
640 
641 		/* If we are starting a new section then prepare it now */
642 		if (next_state != state || force_new_sect) {
643 			KRL_DBG(("%s: start state 0x%02x", __func__,
644 			    next_state));
645 			state = next_state;
646 			sshbuf_reset(sect);
647 			switch (state) {
648 			case KRL_SECTION_CERT_SERIAL_LIST:
649 			case KRL_SECTION_CERT_SERIAL_RANGE:
650 				break;
651 			case KRL_SECTION_CERT_SERIAL_BITMAP:
652 				if ((bitmap = bitmap_new()) == NULL) {
653 					r = SSH_ERR_ALLOC_FAIL;
654 					goto out;
655 				}
656 				bitmap_start = rs->lo;
657 				if ((r = sshbuf_put_u64(sect,
658 				    bitmap_start)) != 0)
659 					goto out;
660 				break;
661 			}
662 		}
663 
664 		/* Perform section-specific processing */
665 		switch (state) {
666 		case KRL_SECTION_CERT_SERIAL_LIST:
667 			for (i = 0; i < contig; i++) {
668 				if ((r = sshbuf_put_u64(sect, rs->lo + i)) != 0)
669 					goto out;
670 			}
671 			break;
672 		case KRL_SECTION_CERT_SERIAL_RANGE:
673 			if ((r = sshbuf_put_u64(sect, rs->lo)) != 0 ||
674 			    (r = sshbuf_put_u64(sect, rs->hi)) != 0)
675 				goto out;
676 			break;
677 		case KRL_SECTION_CERT_SERIAL_BITMAP:
678 			if (rs->lo - bitmap_start > INT_MAX) {
679 				error("%s: insane bitmap gap", __func__);
680 				goto out;
681 			}
682 			for (i = 0; i < contig; i++) {
683 				if (bitmap_set_bit(bitmap,
684 				    rs->lo + i - bitmap_start) != 0) {
685 					r = SSH_ERR_ALLOC_FAIL;
686 					goto out;
687 				}
688 			}
689 			break;
690 		}
691 		last = rs->hi;
692 	}
693 	/* Flush the remaining section, if any */
694 	if (state != 0) {
695 		KRL_DBG(("%s: serial final flush for state 0x%02x",
696 		    __func__, state));
697 		switch (state) {
698 		case KRL_SECTION_CERT_SERIAL_LIST:
699 		case KRL_SECTION_CERT_SERIAL_RANGE:
700 			break;
701 		case KRL_SECTION_CERT_SERIAL_BITMAP:
702 			if ((r = put_bitmap(sect, bitmap)) != 0)
703 				goto out;
704 			bitmap_free(bitmap);
705 			bitmap = NULL;
706 			break;
707 		}
708 		if ((r = sshbuf_put_u8(buf, state)) != 0 ||
709 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
710 			goto out;
711 	}
712 	KRL_DBG(("%s: serial done ", __func__));
713 
714 	/* Now output a section for any revocations by key ID */
715 	sshbuf_reset(sect);
716 	RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
717 		KRL_DBG(("%s: key ID %s", __func__, rki->key_id));
718 		if ((r = sshbuf_put_cstring(sect, rki->key_id)) != 0)
719 			goto out;
720 	}
721 	if (sshbuf_len(sect) != 0) {
722 		if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERT_KEY_ID)) != 0 ||
723 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
724 			goto out;
725 	}
726 	r = 0;
727  out:
728 	bitmap_free(bitmap);
729 	sshbuf_free(sect);
730 	return r;
731 }
732 
733 int
ssh_krl_to_blob(struct ssh_krl * krl,struct sshbuf * buf,struct sshkey ** sign_keys,u_int nsign_keys)734 ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
735     struct sshkey **sign_keys, u_int nsign_keys)
736 {
737 	int r = SSH_ERR_INTERNAL_ERROR;
738 	struct revoked_certs *rc;
739 	struct revoked_blob *rb;
740 	struct sshbuf *sect;
741 	u_char *sblob = NULL;
742 	size_t slen, i;
743 
744 	if (krl->generated_date == 0)
745 		krl->generated_date = time(NULL);
746 
747 	if ((sect = sshbuf_new()) == NULL)
748 		return SSH_ERR_ALLOC_FAIL;
749 
750 	/* Store the header */
751 	if ((r = sshbuf_put(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1)) != 0 ||
752 	    (r = sshbuf_put_u32(buf, KRL_FORMAT_VERSION)) != 0 ||
753 	    (r = sshbuf_put_u64(buf, krl->krl_version)) != 0 ||
754 	    (r = sshbuf_put_u64(buf, krl->generated_date)) != 0 ||
755 	    (r = sshbuf_put_u64(buf, krl->flags)) != 0 ||
756 	    (r = sshbuf_put_string(buf, NULL, 0)) != 0 ||
757 	    (r = sshbuf_put_cstring(buf, krl->comment)) != 0)
758 		goto out;
759 
760 	/* Store sections for revoked certificates */
761 	TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
762 		sshbuf_reset(sect);
763 		if ((r = revoked_certs_generate(rc, sect)) != 0)
764 			goto out;
765 		if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERTIFICATES)) != 0 ||
766 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
767 			goto out;
768 	}
769 
770 	/* Finally, output sections for revocations by public key/hash */
771 	sshbuf_reset(sect);
772 	RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
773 		KRL_DBG(("%s: key len %zu ", __func__, rb->len));
774 		if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
775 			goto out;
776 	}
777 	if (sshbuf_len(sect) != 0) {
778 		if ((r = sshbuf_put_u8(buf, KRL_SECTION_EXPLICIT_KEY)) != 0 ||
779 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
780 			goto out;
781 	}
782 	sshbuf_reset(sect);
783 	RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
784 		KRL_DBG(("%s: hash len %zu ", __func__, rb->len));
785 		if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
786 			goto out;
787 	}
788 	if (sshbuf_len(sect) != 0) {
789 		if ((r = sshbuf_put_u8(buf,
790 		    KRL_SECTION_FINGERPRINT_SHA1)) != 0 ||
791 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
792 			goto out;
793 	}
794 	sshbuf_reset(sect);
795 	RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) {
796 		KRL_DBG(("%s: hash len %zu ", __func__, rb->len));
797 		if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0)
798 			goto out;
799 	}
800 	if (sshbuf_len(sect) != 0) {
801 		if ((r = sshbuf_put_u8(buf,
802 		    KRL_SECTION_FINGERPRINT_SHA256)) != 0 ||
803 		    (r = sshbuf_put_stringb(buf, sect)) != 0)
804 			goto out;
805 	}
806 
807 	for (i = 0; i < nsign_keys; i++) {
808 		KRL_DBG(("%s: signature key %s", __func__,
809 		    sshkey_ssh_name(sign_keys[i])));
810 		if ((r = sshbuf_put_u8(buf, KRL_SECTION_SIGNATURE)) != 0 ||
811 		    (r = sshkey_puts(sign_keys[i], buf)) != 0)
812 			goto out;
813 
814 		if ((r = sshkey_sign(sign_keys[i], &sblob, &slen,
815 		    sshbuf_ptr(buf), sshbuf_len(buf), NULL, 0)) != 0)
816 			goto out;
817 		KRL_DBG(("%s: signature sig len %zu", __func__, slen));
818 		if ((r = sshbuf_put_string(buf, sblob, slen)) != 0)
819 			goto out;
820 	}
821 
822 	r = 0;
823  out:
824 	free(sblob);
825 	sshbuf_free(sect);
826 	return r;
827 }
828 
829 static void
format_timestamp(u_int64_t timestamp,char * ts,size_t nts)830 format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
831 {
832 	time_t t;
833 	struct tm *tm;
834 
835 	t = timestamp;
836 	tm = localtime(&t);
837 	if (tm == NULL)
838 		strlcpy(ts, "<INVALID>", nts);
839 	else {
840 		*ts = '\0';
841 		strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
842 	}
843 }
844 
845 static int
parse_revoked_certs(struct sshbuf * buf,struct ssh_krl * krl)846 parse_revoked_certs(struct sshbuf *buf, struct ssh_krl *krl)
847 {
848 	int r = SSH_ERR_INTERNAL_ERROR;
849 	u_char type;
850 	const u_char *blob;
851 	size_t blen, nbits;
852 	struct sshbuf *subsect = NULL;
853 	u_int64_t serial, serial_lo, serial_hi;
854 	struct bitmap *bitmap = NULL;
855 	char *key_id = NULL;
856 	struct sshkey *ca_key = NULL;
857 
858 	if ((subsect = sshbuf_new()) == NULL)
859 		return SSH_ERR_ALLOC_FAIL;
860 
861 	/* Header: key, reserved */
862 	if ((r = sshbuf_get_string_direct(buf, &blob, &blen)) != 0 ||
863 	    (r = sshbuf_skip_string(buf)) != 0)
864 		goto out;
865 	if (blen != 0 && (r = sshkey_from_blob(blob, blen, &ca_key)) != 0)
866 		goto out;
867 
868 	while (sshbuf_len(buf) > 0) {
869 		sshbuf_free(subsect);
870 		subsect = NULL;
871 		if ((r = sshbuf_get_u8(buf, &type)) != 0 ||
872 		    (r = sshbuf_froms(buf, &subsect)) != 0)
873 			goto out;
874 		KRL_DBG(("%s: subsection type 0x%02x", __func__, type));
875 		/* sshbuf_dump(subsect, stderr); */
876 
877 		switch (type) {
878 		case KRL_SECTION_CERT_SERIAL_LIST:
879 			while (sshbuf_len(subsect) > 0) {
880 				if ((r = sshbuf_get_u64(subsect, &serial)) != 0)
881 					goto out;
882 				if ((r = ssh_krl_revoke_cert_by_serial(krl,
883 				    ca_key, serial)) != 0)
884 					goto out;
885 			}
886 			break;
887 		case KRL_SECTION_CERT_SERIAL_RANGE:
888 			if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
889 			    (r = sshbuf_get_u64(subsect, &serial_hi)) != 0)
890 				goto out;
891 			if ((r = ssh_krl_revoke_cert_by_serial_range(krl,
892 			    ca_key, serial_lo, serial_hi)) != 0)
893 				goto out;
894 			break;
895 		case KRL_SECTION_CERT_SERIAL_BITMAP:
896 			if ((bitmap = bitmap_new()) == NULL) {
897 				r = SSH_ERR_ALLOC_FAIL;
898 				goto out;
899 			}
900 			if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 ||
901 			    (r = sshbuf_get_bignum2_bytes_direct(subsect,
902 			    &blob, &blen)) != 0)
903 				goto out;
904 			if (bitmap_from_string(bitmap, blob, blen) != 0) {
905 				r = SSH_ERR_INVALID_FORMAT;
906 				goto out;
907 			}
908 			nbits = bitmap_nbits(bitmap);
909 			for (serial = 0; serial < (u_int64_t)nbits; serial++) {
910 				if (serial > 0 && serial_lo + serial == 0) {
911 					error("%s: bitmap wraps u64", __func__);
912 					r = SSH_ERR_INVALID_FORMAT;
913 					goto out;
914 				}
915 				if (!bitmap_test_bit(bitmap, serial))
916 					continue;
917 				if ((r = ssh_krl_revoke_cert_by_serial(krl,
918 				    ca_key, serial_lo + serial)) != 0)
919 					goto out;
920 			}
921 			bitmap_free(bitmap);
922 			bitmap = NULL;
923 			break;
924 		case KRL_SECTION_CERT_KEY_ID:
925 			while (sshbuf_len(subsect) > 0) {
926 				if ((r = sshbuf_get_cstring(subsect,
927 				    &key_id, NULL)) != 0)
928 					goto out;
929 				if ((r = ssh_krl_revoke_cert_by_key_id(krl,
930 				    ca_key, key_id)) != 0)
931 					goto out;
932 				free(key_id);
933 				key_id = NULL;
934 			}
935 			break;
936 		default:
937 			error("Unsupported KRL certificate section %u", type);
938 			r = SSH_ERR_INVALID_FORMAT;
939 			goto out;
940 		}
941 		if (sshbuf_len(subsect) > 0) {
942 			error("KRL certificate section contains unparsed data");
943 			r = SSH_ERR_INVALID_FORMAT;
944 			goto out;
945 		}
946 	}
947 
948 	r = 0;
949  out:
950 	if (bitmap != NULL)
951 		bitmap_free(bitmap);
952 	free(key_id);
953 	sshkey_free(ca_key);
954 	sshbuf_free(subsect);
955 	return r;
956 }
957 
958 static int
blob_section(struct sshbuf * sect,struct revoked_blob_tree * target_tree,size_t expected_len)959 blob_section(struct sshbuf *sect, struct revoked_blob_tree *target_tree,
960     size_t expected_len)
961 {
962 	u_char *rdata = NULL;
963 	size_t rlen = 0;
964 	int r;
965 
966 	while (sshbuf_len(sect) > 0) {
967 		if ((r = sshbuf_get_string(sect, &rdata, &rlen)) != 0)
968 			return r;
969 		if (expected_len != 0 && rlen != expected_len) {
970 			error("%s: bad length", __func__);
971 			free(rdata);
972 			return SSH_ERR_INVALID_FORMAT;
973 		}
974 		if ((r = revoke_blob(target_tree, rdata, rlen)) != 0) {
975 			free(rdata);
976 			return r;
977 		}
978 	}
979 	return 0;
980 }
981 
982 /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
983 int
ssh_krl_from_blob(struct sshbuf * buf,struct ssh_krl ** krlp,const struct sshkey ** sign_ca_keys,size_t nsign_ca_keys)984 ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
985     const struct sshkey **sign_ca_keys, size_t nsign_ca_keys)
986 {
987 	struct sshbuf *copy = NULL, *sect = NULL;
988 	struct ssh_krl *krl = NULL;
989 	char timestamp[64];
990 	int r = SSH_ERR_INTERNAL_ERROR, sig_seen;
991 	struct sshkey *key = NULL, **ca_used = NULL, **tmp_ca_used;
992 	u_char type;
993 	const u_char *blob;
994 	size_t i, j, sig_off, sects_off, blen, nca_used;
995 	u_int format_version;
996 
997 	nca_used = 0;
998 	*krlp = NULL;
999 	if (sshbuf_len(buf) < sizeof(KRL_MAGIC) - 1 ||
1000 	    memcmp(sshbuf_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
1001 		debug3("%s: not a KRL", __func__);
1002 		return SSH_ERR_KRL_BAD_MAGIC;
1003 	}
1004 
1005 	/* Take a copy of the KRL buffer so we can verify its signature later */
1006 	if ((copy = sshbuf_fromb(buf)) == NULL) {
1007 		r = SSH_ERR_ALLOC_FAIL;
1008 		goto out;
1009 	}
1010 	if ((r = sshbuf_consume(copy, sizeof(KRL_MAGIC) - 1)) != 0)
1011 		goto out;
1012 
1013 	if ((krl = ssh_krl_init()) == NULL) {
1014 		error("%s: alloc failed", __func__);
1015 		goto out;
1016 	}
1017 
1018 	if ((r = sshbuf_get_u32(copy, &format_version)) != 0)
1019 		goto out;
1020 	if (format_version != KRL_FORMAT_VERSION) {
1021 		r = SSH_ERR_INVALID_FORMAT;
1022 		goto out;
1023 	}
1024 	if ((r = sshbuf_get_u64(copy, &krl->krl_version)) != 0 ||
1025 	    (r = sshbuf_get_u64(copy, &krl->generated_date)) != 0 ||
1026 	    (r = sshbuf_get_u64(copy, &krl->flags)) != 0 ||
1027 	    (r = sshbuf_skip_string(copy)) != 0 ||
1028 	    (r = sshbuf_get_cstring(copy, &krl->comment, NULL)) != 0)
1029 		goto out;
1030 
1031 	format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1032 	debug("KRL version %llu generated at %s%s%s",
1033 	    (long long unsigned)krl->krl_version, timestamp,
1034 	    *krl->comment ? ": " : "", krl->comment);
1035 
1036 	/*
1037 	 * 1st pass: verify signatures, if any. This is done to avoid
1038 	 * detailed parsing of data whose provenance is unverified.
1039 	 */
1040 	sig_seen = 0;
1041 	if (sshbuf_len(buf) < sshbuf_len(copy)) {
1042 		/* Shouldn't happen */
1043 		r = SSH_ERR_INTERNAL_ERROR;
1044 		goto out;
1045 	}
1046 	sects_off = sshbuf_len(buf) - sshbuf_len(copy);
1047 	while (sshbuf_len(copy) > 0) {
1048 		if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1049 		    (r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0)
1050 			goto out;
1051 		KRL_DBG(("%s: first pass, section 0x%02x", __func__, type));
1052 		if (type != KRL_SECTION_SIGNATURE) {
1053 			if (sig_seen) {
1054 				error("KRL contains non-signature section "
1055 				    "after signature");
1056 				r = SSH_ERR_INVALID_FORMAT;
1057 				goto out;
1058 			}
1059 			/* Not interested for now. */
1060 			continue;
1061 		}
1062 		sig_seen = 1;
1063 		/* First string component is the signing key */
1064 		if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
1065 			r = SSH_ERR_INVALID_FORMAT;
1066 			goto out;
1067 		}
1068 		if (sshbuf_len(buf) < sshbuf_len(copy)) {
1069 			/* Shouldn't happen */
1070 			r = SSH_ERR_INTERNAL_ERROR;
1071 			goto out;
1072 		}
1073 		sig_off = sshbuf_len(buf) - sshbuf_len(copy);
1074 		/* Second string component is the signature itself */
1075 		if ((r = sshbuf_get_string_direct(copy, &blob, &blen)) != 0) {
1076 			r = SSH_ERR_INVALID_FORMAT;
1077 			goto out;
1078 		}
1079 		/* Check signature over entire KRL up to this point */
1080 		if ((r = sshkey_verify(key, blob, blen,
1081 		    sshbuf_ptr(buf), sig_off, NULL, 0)) != 0)
1082 			goto out;
1083 		/* Check if this key has already signed this KRL */
1084 		for (i = 0; i < nca_used; i++) {
1085 			if (sshkey_equal(ca_used[i], key)) {
1086 				error("KRL signed more than once with "
1087 				    "the same key");
1088 				r = SSH_ERR_INVALID_FORMAT;
1089 				goto out;
1090 			}
1091 		}
1092 		/* Record keys used to sign the KRL */
1093 		tmp_ca_used = recallocarray(ca_used, nca_used, nca_used + 1,
1094 		    sizeof(*ca_used));
1095 		if (tmp_ca_used == NULL) {
1096 			r = SSH_ERR_ALLOC_FAIL;
1097 			goto out;
1098 		}
1099 		ca_used = tmp_ca_used;
1100 		ca_used[nca_used++] = key;
1101 		key = NULL;
1102 	}
1103 
1104 	if (sshbuf_len(copy) != 0) {
1105 		/* Shouldn't happen */
1106 		r = SSH_ERR_INTERNAL_ERROR;
1107 		goto out;
1108 	}
1109 
1110 	/*
1111 	 * 2nd pass: parse and load the KRL, skipping the header to the point
1112 	 * where the section start.
1113 	 */
1114 	sshbuf_free(copy);
1115 	if ((copy = sshbuf_fromb(buf)) == NULL) {
1116 		r = SSH_ERR_ALLOC_FAIL;
1117 		goto out;
1118 	}
1119 	if ((r = sshbuf_consume(copy, sects_off)) != 0)
1120 		goto out;
1121 	while (sshbuf_len(copy) > 0) {
1122 		sshbuf_free(sect);
1123 		sect = NULL;
1124 		if ((r = sshbuf_get_u8(copy, &type)) != 0 ||
1125 		    (r = sshbuf_froms(copy, &sect)) != 0)
1126 			goto out;
1127 		KRL_DBG(("%s: second pass, section 0x%02x", __func__, type));
1128 
1129 		switch (type) {
1130 		case KRL_SECTION_CERTIFICATES:
1131 			if ((r = parse_revoked_certs(sect, krl)) != 0)
1132 				goto out;
1133 			break;
1134 		case KRL_SECTION_EXPLICIT_KEY:
1135 			if ((r = blob_section(sect,
1136 			    &krl->revoked_keys, 0)) != 0)
1137 				goto out;
1138 			break;
1139 		case KRL_SECTION_FINGERPRINT_SHA1:
1140 			if ((r = blob_section(sect,
1141 			    &krl->revoked_sha1s, 20)) != 0)
1142 				goto out;
1143 			break;
1144 		case KRL_SECTION_FINGERPRINT_SHA256:
1145 			if ((r = blob_section(sect,
1146 			    &krl->revoked_sha256s, 32)) != 0)
1147 				goto out;
1148 			break;
1149 		case KRL_SECTION_SIGNATURE:
1150 			/* Handled above, but still need to stay in synch */
1151 			sshbuf_free(sect);
1152 			sect = NULL;
1153 			if ((r = sshbuf_skip_string(copy)) != 0)
1154 				goto out;
1155 			break;
1156 		default:
1157 			error("Unsupported KRL section %u", type);
1158 			r = SSH_ERR_INVALID_FORMAT;
1159 			goto out;
1160 		}
1161 		if (sect != NULL && sshbuf_len(sect) > 0) {
1162 			error("KRL section contains unparsed data");
1163 			r = SSH_ERR_INVALID_FORMAT;
1164 			goto out;
1165 		}
1166 	}
1167 
1168 	/* Check that the key(s) used to sign the KRL weren't revoked */
1169 	sig_seen = 0;
1170 	for (i = 0; i < nca_used; i++) {
1171 		if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1172 			sig_seen = 1;
1173 		else {
1174 			sshkey_free(ca_used[i]);
1175 			ca_used[i] = NULL;
1176 		}
1177 	}
1178 	if (nca_used && !sig_seen) {
1179 		error("All keys used to sign KRL were revoked");
1180 		r = SSH_ERR_KEY_REVOKED;
1181 		goto out;
1182 	}
1183 
1184 	/* If we have CA keys, then verify that one was used to sign the KRL */
1185 	if (sig_seen && nsign_ca_keys != 0) {
1186 		sig_seen = 0;
1187 		for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1188 			for (j = 0; j < nca_used; j++) {
1189 				if (ca_used[j] == NULL)
1190 					continue;
1191 				if (sshkey_equal(ca_used[j], sign_ca_keys[i])) {
1192 					sig_seen = 1;
1193 					break;
1194 				}
1195 			}
1196 		}
1197 		if (!sig_seen) {
1198 			r = SSH_ERR_SIGNATURE_INVALID;
1199 			error("KRL not signed with any trusted key");
1200 			goto out;
1201 		}
1202 	}
1203 
1204 	*krlp = krl;
1205 	r = 0;
1206  out:
1207 	if (r != 0)
1208 		ssh_krl_free(krl);
1209 	for (i = 0; i < nca_used; i++)
1210 		sshkey_free(ca_used[i]);
1211 	free(ca_used);
1212 	sshkey_free(key);
1213 	sshbuf_free(copy);
1214 	sshbuf_free(sect);
1215 	return r;
1216 }
1217 
1218 /* Checks certificate serial number and key ID revocation */
1219 static int
is_cert_revoked(const struct sshkey * key,struct revoked_certs * rc)1220 is_cert_revoked(const struct sshkey *key, struct revoked_certs *rc)
1221 {
1222 	struct revoked_serial rs, *ers;
1223 	struct revoked_key_id rki, *erki;
1224 
1225 	/* Check revocation by cert key ID */
1226 	memset(&rki, 0, sizeof(rki));
1227 	rki.key_id = key->cert->key_id;
1228 	erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1229 	if (erki != NULL) {
1230 		KRL_DBG(("%s: revoked by key ID", __func__));
1231 		return SSH_ERR_KEY_REVOKED;
1232 	}
1233 
1234 	/*
1235 	 * Zero serials numbers are ignored (it's the default when the
1236 	 * CA doesn't specify one).
1237 	 */
1238 	if (key->cert->serial == 0)
1239 		return 0;
1240 
1241 	memset(&rs, 0, sizeof(rs));
1242 	rs.lo = rs.hi = key->cert->serial;
1243 	ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1244 	if (ers != NULL) {
1245 		KRL_DBG(("%s: revoked serial %llu matched %llu:%llu", __func__,
1246 		    key->cert->serial, ers->lo, ers->hi));
1247 		return SSH_ERR_KEY_REVOKED;
1248 	}
1249 	return 0;
1250 }
1251 
1252 /* Checks whether a given key/cert is revoked. Does not check its CA */
1253 static int
is_key_revoked(struct ssh_krl * krl,const struct sshkey * key)1254 is_key_revoked(struct ssh_krl *krl, const struct sshkey *key)
1255 {
1256 	struct revoked_blob rb, *erb;
1257 	struct revoked_certs *rc;
1258 	int r;
1259 
1260 	/* Check explicitly revoked hashes first */
1261 	memset(&rb, 0, sizeof(rb));
1262 	if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA1,
1263 	    &rb.blob, &rb.len)) != 0)
1264 		return r;
1265 	erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1266 	free(rb.blob);
1267 	if (erb != NULL) {
1268 		KRL_DBG(("%s: revoked by key SHA1", __func__));
1269 		return SSH_ERR_KEY_REVOKED;
1270 	}
1271 	memset(&rb, 0, sizeof(rb));
1272 	if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA256,
1273 	    &rb.blob, &rb.len)) != 0)
1274 		return r;
1275 	erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha256s, &rb);
1276 	free(rb.blob);
1277 	if (erb != NULL) {
1278 		KRL_DBG(("%s: revoked by key SHA256", __func__));
1279 		return SSH_ERR_KEY_REVOKED;
1280 	}
1281 
1282 	/* Next, explicit keys */
1283 	memset(&rb, 0, sizeof(rb));
1284 	if ((r = plain_key_blob(key, &rb.blob, &rb.len)) != 0)
1285 		return r;
1286 	erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1287 	free(rb.blob);
1288 	if (erb != NULL) {
1289 		KRL_DBG(("%s: revoked by explicit key", __func__));
1290 		return SSH_ERR_KEY_REVOKED;
1291 	}
1292 
1293 	if (!sshkey_is_cert(key))
1294 		return 0;
1295 
1296 	/* Check cert revocation for the specified CA */
1297 	if ((r = revoked_certs_for_ca_key(krl, key->cert->signature_key,
1298 	    &rc, 0)) != 0)
1299 		return r;
1300 	if (rc != NULL) {
1301 		if ((r = is_cert_revoked(key, rc)) != 0)
1302 			return r;
1303 	}
1304 	/* Check cert revocation for the wildcard CA */
1305 	if ((r = revoked_certs_for_ca_key(krl, NULL, &rc, 0)) != 0)
1306 		return r;
1307 	if (rc != NULL) {
1308 		if ((r = is_cert_revoked(key, rc)) != 0)
1309 			return r;
1310 	}
1311 
1312 	KRL_DBG(("%s: %llu no match", __func__, key->cert->serial));
1313 	return 0;
1314 }
1315 
1316 int
ssh_krl_check_key(struct ssh_krl * krl,const struct sshkey * key)1317 ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key)
1318 {
1319 	int r;
1320 
1321 	KRL_DBG(("%s: checking key", __func__));
1322 	if ((r = is_key_revoked(krl, key)) != 0)
1323 		return r;
1324 	if (sshkey_is_cert(key)) {
1325 		debug2("%s: checking CA key", __func__);
1326 		if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1327 			return r;
1328 	}
1329 	KRL_DBG(("%s: key okay", __func__));
1330 	return 0;
1331 }
1332 
1333 int
ssh_krl_file_contains_key(const char * path,const struct sshkey * key)1334 ssh_krl_file_contains_key(const char *path, const struct sshkey *key)
1335 {
1336 	struct sshbuf *krlbuf = NULL;
1337 	struct ssh_krl *krl = NULL;
1338 	int oerrno = 0, r, fd;
1339 
1340 	if (path == NULL)
1341 		return 0;
1342 
1343 	if ((krlbuf = sshbuf_new()) == NULL)
1344 		return SSH_ERR_ALLOC_FAIL;
1345 	if ((fd = open(path, O_RDONLY)) == -1) {
1346 		r = SSH_ERR_SYSTEM_ERROR;
1347 		oerrno = errno;
1348 		goto out;
1349 	}
1350 	if ((r = sshkey_load_file(fd, krlbuf)) != 0) {
1351 		oerrno = errno;
1352 		goto out;
1353 	}
1354 	if ((r = ssh_krl_from_blob(krlbuf, &krl, NULL, 0)) != 0)
1355 		goto out;
1356 	debug2("%s: checking KRL %s", __func__, path);
1357 	r = ssh_krl_check_key(krl, key);
1358  out:
1359 	if (fd != -1)
1360 		close(fd);
1361 	sshbuf_free(krlbuf);
1362 	ssh_krl_free(krl);
1363 	if (r != 0)
1364 		errno = oerrno;
1365 	return r;
1366 }
1367