xref: /openssh-portable/krl.c (revision 816036f1)
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 1.52 2020/10/18 11:32:01 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, &sect)) != 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: SHA256:%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