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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 1.2 2013/01/18 00:24:58 djm Exp $ */
18
19#include "includes.h"
20
21#include <sys/types.h>
22#include <sys/param.h>
23#include <sys/tree.h>
24#include <sys/queue.h>
25
26#include <errno.h>
27#include <fcntl.h>
28#include <limits.h>
29#include <string.h>
30#include <time.h>
31#include <unistd.h>
32
33#include "buffer.h"
34#include "key.h"
35#include "authfile.h"
36#include "err.h"
37#include "misc.h"
38#include "log.h"
39#include "xmalloc.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 */
56struct revoked_serial {
57 u_int64_t lo, hi;
58 RB_ENTRY(revoked_serial) tree_entry;
59};
60static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b);
61RB_HEAD(revoked_serial_tree, revoked_serial);
62RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp);
63
64/* Tree of key IDs */
65struct revoked_key_id {
66 char *key_id;
67 RB_ENTRY(revoked_key_id) tree_entry;
68};
69static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b);
70RB_HEAD(revoked_key_id_tree, revoked_key_id);
71RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp);
72
73/* Tree of blobs (used for keys and fingerprints) */
74struct revoked_blob {
75 u_char *blob;
76 u_int len;
77 RB_ENTRY(revoked_blob) tree_entry;
78};
79static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b);
80RB_HEAD(revoked_blob_tree, revoked_blob);
81RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp);
82
83/* Tracks revoked certs for a single CA */
84struct revoked_certs {
85 Key *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};
90TAILQ_HEAD(revoked_certs_list, revoked_certs);
91
92struct 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_certs_list revoked_certs;
100};
101
102/* Return equal if a and b overlap */
103static int
104serial_cmp(struct revoked_serial *a, struct revoked_serial *b)
105{
106 if (a->hi >= b->lo && a->lo <= b->hi)
107 return 0;
108 return a->lo < b->lo ? -1 : 1;
109}
110
111static int
112key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b)
113{
114 return strcmp(a->key_id, b->key_id);
115}
116
117static int
118blob_cmp(struct revoked_blob *a, struct revoked_blob *b)
119{
120 int r;
121
122 if (a->len != b->len) {
123 if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0)
124 return r;
125 return a->len > b->len ? 1 : -1;
126 } else
127 return memcmp(a->blob, b->blob, a->len);
128}
129
130struct ssh_krl *
131ssh_krl_init(void)
132{
133 struct ssh_krl *krl;
134
135 if ((krl = calloc(1, sizeof(*krl))) == NULL)
136 return NULL;
137 RB_INIT(&krl->revoked_keys);
138 RB_INIT(&krl->revoked_sha1s);
139 TAILQ_INIT(&krl->revoked_certs);
140 return krl;
141}
142
143static void
144revoked_certs_free(struct revoked_certs *rc)
145{
146 struct revoked_serial *rs, *trs;
147 struct revoked_key_id *rki, *trki;
148
149 RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) {
150 RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs);
151 free(rs);
152 }
153 RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) {
154 RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki);
155 free(rki->key_id);
156 free(rki);
157 }
158 if (rc->ca_key != NULL)
159 key_free(rc->ca_key);
160}
161
162void
163ssh_krl_free(struct ssh_krl *krl)
164{
165 struct revoked_blob *rb, *trb;
166 struct revoked_certs *rc, *trc;
167
168 if (krl == NULL)
169 return;
170
171 free(krl->comment);
172 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) {
173 RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb);
174 free(rb->blob);
175 free(rb);
176 }
177 RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) {
178 RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb);
179 free(rb->blob);
180 free(rb);
181 }
182 TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) {
183 TAILQ_REMOVE(&krl->revoked_certs, rc, entry);
184 revoked_certs_free(rc);
185 }
186}
187
188void
189ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version)
190{
191 krl->krl_version = version;
192}
193
194void
195ssh_krl_set_comment(struct ssh_krl *krl, const char *comment)
196{
197 free(krl->comment);
198 if ((krl->comment = strdup(comment)) == NULL)
199 fatal("%s: strdup", __func__);
200}
201
202/*
203 * Find the revoked_certs struct for a CA key. If allow_create is set then
204 * create a new one in the tree if one did not exist already.
205 */
206static int
207revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key,
208 struct revoked_certs **rcp, int allow_create)
209{
210 struct revoked_certs *rc;
211
212 *rcp = NULL;
213 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
214 if (key_equal(rc->ca_key, ca_key)) {
215 *rcp = rc;
216 return 0;
217 }
218 }
219 if (!allow_create)
220 return 0;
221 /* If this CA doesn't exist in the list then add it now */
222 if ((rc = calloc(1, sizeof(*rc))) == NULL)
223 return -1;
224 if ((rc->ca_key = key_from_private(ca_key)) == NULL) {
225 free(rc);
226 return -1;
227 }
228 RB_INIT(&rc->revoked_serials);
229 RB_INIT(&rc->revoked_key_ids);
230 TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry);
231 debug3("%s: new CA %s", __func__, key_type(ca_key));
232 *rcp = rc;
233 return 0;
234}
235
236static int
237insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi)
238{
239 struct revoked_serial rs, *ers, *crs, *irs;
240
241 KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi));
242 bzero(&rs, sizeof(rs));
243 rs.lo = lo;
244 rs.hi = hi;
245 ers = RB_NFIND(revoked_serial_tree, rt, &rs);
246 if (ers == NULL || serial_cmp(ers, &rs) != 0) {
247 /* No entry matches. Just insert */
248 if ((irs = malloc(sizeof(rs))) == NULL)
249 return -1;
250 memcpy(irs, &rs, sizeof(*irs));
251 ers = RB_INSERT(revoked_serial_tree, rt, irs);
252 if (ers != NULL) {
253 KRL_DBG(("%s: bad: ers != NULL", __func__));
254 /* Shouldn't happen */
255 free(ers);
256 return -1;
257 }
258 ers = irs;
259 } else {
260 KRL_DBG(("%s: overlap found %llu:%llu", __func__,
261 ers->lo, ers->hi));
262 /*
263 * The inserted entry overlaps an existing one. Grow the
264 * existing entry.
265 */
266 if (ers->lo > lo)
267 ers->lo = lo;
268 if (ers->hi < hi)
269 ers->hi = hi;
270 }
271 /*
272 * The inserted or revised range might overlap or abut adjacent ones;
273 * coalesce as necessary.
274 */
275
276 /* Check predecessors */
277 while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) {
278 KRL_DBG(("%s: pred %llu:%llu", __func__, crs->lo, crs->hi));
279 if (ers->lo != 0 && crs->hi < ers->lo - 1)
280 break;
281 /* This entry overlaps. */
282 if (crs->lo < ers->lo) {
283 ers->lo = crs->lo;
284 KRL_DBG(("%s: pred extend %llu:%llu", __func__,
285 ers->lo, ers->hi));
286 }
287 RB_REMOVE(revoked_serial_tree, rt, crs);
288 free(crs);
289 }
290 /* Check successors */
291 while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) {
292 KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi));
293 if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1)
294 break;
295 /* This entry overlaps. */
296 if (crs->hi > ers->hi) {
297 ers->hi = crs->hi;
298 KRL_DBG(("%s: succ extend %llu:%llu", __func__,
299 ers->lo, ers->hi));
300 }
301 RB_REMOVE(revoked_serial_tree, rt, crs);
302 free(crs);
303 }
304 KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi));
305 return 0;
306}
307
308int
309ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key,
310 u_int64_t serial)
311{
312 return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial);
313}
314
315int
316ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key,
317 u_int64_t lo, u_int64_t hi)
318{
319 struct revoked_certs *rc;
320
321 if (lo > hi || lo == 0)
322 return -1;
323 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0)
324 return -1;
325 return insert_serial_range(&rc->revoked_serials, lo, hi);
326}
327
328int
329ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key,
330 const char *key_id)
331{
332 struct revoked_key_id *rki, *erki;
333 struct revoked_certs *rc;
334
335 if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0)
336 return -1;
337
338 debug3("%s: revoke %s", __func__, key_id);
339 if ((rki = calloc(1, sizeof(*rki))) == NULL ||
340 (rki->key_id = strdup(key_id)) == NULL) {
341 free(rki);
342 fatal("%s: strdup", __func__);
343 }
344 erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki);
345 if (erki != NULL) {
346 free(rki->key_id);
347 free(rki);
348 }
349 return 0;
350}
351
352/* Convert "key" to a public key blob without any certificate information */
353static int
354plain_key_blob(const Key *key, u_char **blob, u_int *blen)
355{
356 Key *kcopy;
357 int r;
358
359 if ((kcopy = key_from_private(key)) == NULL)
360 return -1;
361 if (key_is_cert(kcopy)) {
362 if (key_drop_cert(kcopy) != 0) {
363 error("%s: key_drop_cert", __func__);
364 key_free(kcopy);
365 return -1;
366 }
367 }
368 r = key_to_blob(kcopy, blob, blen);
369 free(kcopy);
370 return r == 0 ? -1 : 0;
371}
372
373/* Revoke a key blob. Ownership of blob is transferred to the tree */
374static int
375revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len)
376{
377 struct revoked_blob *rb, *erb;
378
379 if ((rb = calloc(1, sizeof(*rb))) == NULL)
380 return -1;
381 rb->blob = blob;
382 rb->len = len;
383 erb = RB_INSERT(revoked_blob_tree, rbt, rb);
384 if (erb != NULL) {
385 free(rb->blob);
386 free(rb);
387 }
388 return 0;
389}
390
391int
392ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key)
393{
394 u_char *blob;
395 u_int len;
396
397 debug3("%s: revoke type %s", __func__, key_type(key));
398 if (plain_key_blob(key, &blob, &len) != 0)
399 return -1;
400 return revoke_blob(&krl->revoked_keys, blob, len);
401}
402
403int
404ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key)
405{
406 u_char *blob;
407 u_int len;
408
409 debug3("%s: revoke type %s by sha1", __func__, key_type(key));
410 if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL)
411 return -1;
412 return revoke_blob(&krl->revoked_sha1s, blob, len);
413}
414
415int
416ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key)
417{
418 if (!key_is_cert(key))
419 return ssh_krl_revoke_key_sha1(krl, key);
420
421 if (key_cert_is_legacy(key) || key->cert->serial == 0) {
422 return ssh_krl_revoke_cert_by_key_id(krl,
423 key->cert->signature_key,
424 key->cert->key_id);
425 } else {
426 return ssh_krl_revoke_cert_by_serial(krl,
427 key->cert->signature_key,
428 key->cert->serial);
429 }
430}
431
432/*
433 * Select a copact next section type to emit in a KRL based on the
434 * current section type, the run length of contiguous revoked serial
435 * numbers and the gaps from the last and to the next revoked serial.
436 * Applies a mostly-accurate bit cost model to select the section type
437 * that will minimise the size of the resultant KRL.
438 */
439static int
440choose_next_state(int current_state, u_int64_t contig, int final,
441 u_int64_t last_gap, u_int64_t next_gap, int *force_new_section)
442{
443 int new_state;
444 u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart;
445
446 /*
447 * Avoid unsigned overflows.
448 * The limits are high enough to avoid confusing the calculations.
449 */
450 contig = MIN(contig, 1ULL<<31);
451 last_gap = MIN(last_gap, 1ULL<<31);
452 next_gap = MIN(next_gap, 1ULL<<31);
453
454 /*
455 * Calculate the cost to switch from the current state to candidates.
456 * NB. range sections only ever contain a single range, so their
457 * switching cost is independent of the current_state.
458 */
459 cost_list = cost_bitmap = cost_bitmap_restart = 0;
460 cost_range = 8;
461 switch (current_state) {
462 case KRL_SECTION_CERT_SERIAL_LIST:
463 cost_bitmap_restart = cost_bitmap = 8 + 64;
464 break;
465 case KRL_SECTION_CERT_SERIAL_BITMAP:
466 cost_list = 8;
467 cost_bitmap_restart = 8 + 64;
468 break;
469 case KRL_SECTION_CERT_SERIAL_RANGE:
470 case 0:
471 cost_bitmap_restart = cost_bitmap = 8 + 64;
472 cost_list = 8;
473 }
474
475 /* Estimate base cost in bits of each section type */
476 cost_list += 64 * contig + (final ? 0 : 8+64);
477 cost_range += (2 * 64) + (final ? 0 : 8+64);
478 cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64));
479 cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64));
480
481 /* Convert to byte costs for actual comparison */
482 cost_list = (cost_list + 7) / 8;
483 cost_bitmap = (cost_bitmap + 7) / 8;
484 cost_bitmap_restart = (cost_bitmap_restart + 7) / 8;
485 cost_range = (cost_range + 7) / 8;
486
487 /* Now pick the best choice */
488 *force_new_section = 0;
489 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
490 cost = cost_bitmap;
491 if (cost_range < cost) {
492 new_state = KRL_SECTION_CERT_SERIAL_RANGE;
493 cost = cost_range;
494 }
495 if (cost_list < cost) {
496 new_state = KRL_SECTION_CERT_SERIAL_LIST;
497 cost = cost_list;
498 }
499 if (cost_bitmap_restart < cost) {
500 new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
501 *force_new_section = 1;
502 cost = cost_bitmap_restart;
503 }
504 debug3("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:"
505 "list %llu range %llu bitmap %llu new bitmap %llu, "
506 "selected 0x%02x%s", __func__, contig, last_gap, next_gap, final,
507 cost_list, cost_range, cost_bitmap, cost_bitmap_restart, new_state,
508 *force_new_section ? " restart" : "");
509 return new_state;
510}
511
512/* Generate a KRL_SECTION_CERTIFICATES KRL section */
513static int
514revoked_certs_generate(struct revoked_certs *rc, Buffer *buf)
515{
516 int final, force_new_sect, r = -1;
517 u_int64_t i, contig, gap, last = 0, bitmap_start = 0;
518 struct revoked_serial *rs, *nrs;
519 struct revoked_key_id *rki;
520 int next_state, state = 0;
521 Buffer sect;
522 u_char *kblob = NULL;
523 u_int klen;
524 BIGNUM *bitmap = NULL;
525
526 /* Prepare CA scope key blob if we have one supplied */
527 if (key_to_blob(rc->ca_key, &kblob, &klen) == 0)
528 return -1;
529
530 buffer_init(&sect);
531
532 /* Store the header */
533 buffer_put_string(buf, kblob, klen);
534 buffer_put_string(buf, NULL, 0); /* Reserved */
535
536 free(kblob);
537
538 /* Store the revoked serials. */
539 for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials);
540 rs != NULL;
541 rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) {
542 debug3("%s: serial %llu:%llu state 0x%02x", __func__,
543 rs->lo, rs->hi, state);
544
545 /* Check contiguous length and gap to next section (if any) */
546 nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
547 final = nrs == NULL;
548 gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
549 contig = 1 + (rs->hi - rs->lo);
550
551 /* Choose next state based on these */
552 next_state = choose_next_state(state, contig, final,
553 state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
554
555 /*
556 * If the current section is a range section or has a different
557 * type to the next section, then finish it off now.
558 */
559 if (state != 0 && (force_new_sect || next_state != state ||
560 state == KRL_SECTION_CERT_SERIAL_RANGE)) {
561 debug3("%s: finish state 0x%02x", __func__, state);
562 switch (state) {
563 case KRL_SECTION_CERT_SERIAL_LIST:
564 case KRL_SECTION_CERT_SERIAL_RANGE:
565 break;
566 case KRL_SECTION_CERT_SERIAL_BITMAP:
567 buffer_put_bignum2(&sect, bitmap);
568 BN_free(bitmap);
569 bitmap = NULL;
570 break;
571 }
572 buffer_put_char(buf, state);
573 buffer_put_string(buf,
574 buffer_ptr(&sect), buffer_len(&sect));
575 }
576
577 /* If we are starting a new section then prepare it now */
578 if (next_state != state || force_new_sect) {
579 debug3("%s: start state 0x%02x", __func__, next_state);
580 state = next_state;
581 buffer_clear(&sect);
582 switch (state) {
583 case KRL_SECTION_CERT_SERIAL_LIST:
584 case KRL_SECTION_CERT_SERIAL_RANGE:
585 break;
586 case KRL_SECTION_CERT_SERIAL_BITMAP:
587 if ((bitmap = BN_new()) == NULL)
588 goto out;
589 bitmap_start = rs->lo;
590 buffer_put_int64(&sect, bitmap_start);
591 break;
592 }
593 }
594
595 /* Perform section-specific processing */
596 switch (state) {
597 case KRL_SECTION_CERT_SERIAL_LIST:
598 for (i = rs->lo; i < contig; i++)
599 buffer_put_int64(&sect, rs->lo + i);
600 break;
601 case KRL_SECTION_CERT_SERIAL_RANGE:
602 buffer_put_int64(&sect, rs->lo);
603 buffer_put_int64(&sect, rs->hi);
604 break;
605 case KRL_SECTION_CERT_SERIAL_BITMAP:
606 if (rs->lo - bitmap_start > INT_MAX) {
607 error("%s: insane bitmap gap", __func__);
608 goto out;
609 }
610 for (i = 0; i < contig; i++) {
611 if (BN_set_bit(bitmap,
612 rs->lo + i - bitmap_start) != 1)
613 goto out;
614 }
615 break;
616 }
617 last = rs->hi;
618 }
619 /* Flush the remaining section, if any */
620 if (state != 0) {
621 debug3("%s: serial final flush for state 0x%02x",
622 __func__, state);
623 switch (state) {
624 case KRL_SECTION_CERT_SERIAL_LIST:
625 case KRL_SECTION_CERT_SERIAL_RANGE:
626 break;
627 case KRL_SECTION_CERT_SERIAL_BITMAP:
628 buffer_put_bignum2(&sect, bitmap);
629 BN_free(bitmap);
630 bitmap = NULL;
631 break;
632 }
633 buffer_put_char(buf, state);
634 buffer_put_string(buf,
635 buffer_ptr(&sect), buffer_len(&sect));
636 }
637 debug3("%s: serial done ", __func__);
638
639 /* Now output a section for any revocations by key ID */
640 buffer_clear(&sect);
641 RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
642 debug3("%s: key ID %s", __func__, rki->key_id);
643 buffer_put_cstring(&sect, rki->key_id);
644 }
645 if (buffer_len(&sect) != 0) {
646 buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID);
647 buffer_put_string(buf, buffer_ptr(&sect),
648 buffer_len(&sect));
649 }
650 r = 0;
651 out:
652 if (bitmap != NULL)
653 BN_free(bitmap);
654 buffer_free(&sect);
655 return r;
656}
657
658int
659ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys,
660 u_int nsign_keys)
661{
662 int r = -1;
663 struct revoked_certs *rc;
664 struct revoked_blob *rb;
665 Buffer sect;
666 u_char *kblob = NULL, *sblob = NULL;
667 u_int klen, slen, i;
668
669 if (krl->generated_date == 0)
670 krl->generated_date = time(NULL);
671
672 buffer_init(&sect);
673
674 /* Store the header */
675 buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1);
676 buffer_put_int(buf, KRL_FORMAT_VERSION);
677 buffer_put_int64(buf, krl->krl_version);
678 buffer_put_int64(buf, krl->generated_date);
679 buffer_put_int64(buf, krl->flags);
680 buffer_put_string(buf, NULL, 0);
681 buffer_put_cstring(buf, krl->comment ? krl->comment : "");
682
683 /* Store sections for revoked certificates */
684 TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
685 if (revoked_certs_generate(rc, &sect) != 0)
686 goto out;
687 buffer_put_char(buf, KRL_SECTION_CERTIFICATES);
688 buffer_put_string(buf, buffer_ptr(&sect),
689 buffer_len(&sect));
690 }
691
692 /* Finally, output sections for revocations by public key/hash */
693 buffer_clear(&sect);
694 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
695 debug3("%s: key len %u ", __func__, rb->len);
696 buffer_put_string(&sect, rb->blob, rb->len);
697 }
698 if (buffer_len(&sect) != 0) {
699 buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY);
700 buffer_put_string(buf, buffer_ptr(&sect),
701 buffer_len(&sect));
702 }
703 buffer_clear(&sect);
704 RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
705 debug3("%s: hash len %u ", __func__, rb->len);
706 buffer_put_string(&sect, rb->blob, rb->len);
707 }
708 if (buffer_len(&sect) != 0) {
709 buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1);
710 buffer_put_string(buf, buffer_ptr(&sect),
711 buffer_len(&sect));
712 }
713
714 for (i = 0; i < nsign_keys; i++) {
715 if (key_to_blob(sign_keys[i], &kblob, &klen) == 0)
716 goto out;
717
718 debug3("%s: signature key len %u", __func__, klen);
719 buffer_put_char(buf, KRL_SECTION_SIGNATURE);
720 buffer_put_string(buf, kblob, klen);
721
722 if (key_sign(sign_keys[i], &sblob, &slen,
723 buffer_ptr(buf), buffer_len(buf)) == -1)
724 goto out;
725 debug3("%s: signature sig len %u", __func__, slen);
726 buffer_put_string(buf, sblob, slen);
727 }
728
729 r = 0;
730 out:
731 free(kblob);
732 free(sblob);
733 buffer_free(&sect);
734 return r;
735}
736
737static void
738format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
739{
740 time_t t;
741 struct tm *tm;
742
743 t = timestamp;
744 tm = localtime(&t);
745 *ts = '\0';
746 strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
747}
748
749static int
750parse_revoked_certs(Buffer *buf, struct ssh_krl *krl)
751{
752 int ret = -1, nbits;
753 u_char type, *blob;
754 u_int blen;
755 Buffer subsect;
756 u_int64_t serial, serial_lo, serial_hi;
757 BIGNUM *bitmap = NULL;
758 char *key_id = NULL;
759 Key *ca_key = NULL;
760
761 buffer_init(&subsect);
762
763 if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL ||
764 buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */
765 error("%s: buffer error", __func__);
766 goto out;
767 }
768 if ((ca_key = key_from_blob(blob, blen)) == NULL)
769 goto out;
770
771 while (buffer_len(buf) > 0) {
772 if (buffer_get_char_ret(&type, buf) != 0 ||
773 (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) {
774 error("%s: buffer error", __func__);
775 goto out;
776 }
777 buffer_clear(&subsect);
778 buffer_append(&subsect, blob, blen);
779 debug3("%s: subsection type 0x%02x", __func__, type);
780 /* buffer_dump(&subsect); */
781
782 switch (type) {
783 case KRL_SECTION_CERT_SERIAL_LIST:
784 while (buffer_len(&subsect) > 0) {
785 if (buffer_get_int64_ret(&serial,
786 &subsect) != 0) {
787 error("%s: buffer error", __func__);
788 goto out;
789 }
790 if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
791 serial) != 0) {
792 error("%s: update failed", __func__);
793 goto out;
794 }
795 }
796 break;
797 case KRL_SECTION_CERT_SERIAL_RANGE:
798 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
799 buffer_get_int64_ret(&serial_hi, &subsect) != 0) {
800 error("%s: buffer error", __func__);
801 goto out;
802 }
803 if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key,
804 serial_lo, serial_hi) != 0) {
805 error("%s: update failed", __func__);
806 goto out;
807 }
808 break;
809 case KRL_SECTION_CERT_SERIAL_BITMAP:
810 if ((bitmap = BN_new()) == NULL) {
811 error("%s: BN_new", __func__);
812 goto out;
813 }
814 if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
815 buffer_get_bignum2_ret(&subsect, bitmap) != 0) {
816 error("%s: buffer error", __func__);
817 goto out;
818 }
819 if ((nbits = BN_num_bits(bitmap)) < 0) {
820 error("%s: bitmap bits < 0", __func__);
821 goto out;
822 }
823 for (serial = 0; serial < (u_int)nbits; serial++) {
824 if (serial > 0 && serial_lo + serial == 0) {
825 error("%s: bitmap wraps u64", __func__);
826 goto out;
827 }
828 if (!BN_is_bit_set(bitmap, serial))
829 continue;
830 if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
831 serial_lo + serial) != 0) {
832 error("%s: update failed", __func__);
833 goto out;
834 }
835 }
836 BN_free(bitmap);
837 bitmap = NULL;
838 break;
839 case KRL_SECTION_CERT_KEY_ID:
840 while (buffer_len(&subsect) > 0) {
841 if ((key_id = buffer_get_cstring_ret(&subsect,
842 NULL)) == NULL) {
843 error("%s: buffer error", __func__);
844 goto out;
845 }
846 if (ssh_krl_revoke_cert_by_key_id(krl, ca_key,
847 key_id) != 0) {
848 error("%s: update failed", __func__);
849 goto out;
850 }
851 free(key_id);
852 key_id = NULL;
853 }
854 break;
855 default:
856 error("Unsupported KRL certificate section %u", type);
857 goto out;
858 }
859 if (buffer_len(&subsect) > 0) {
860 error("KRL certificate section contains unparsed data");
861 goto out;
862 }
863 }
864
865 ret = 0;
866 out:
867 if (ca_key != NULL)
868 key_free(ca_key);
869 if (bitmap != NULL)
870 BN_free(bitmap);
871 free(key_id);
872 buffer_free(&subsect);
873 return ret;
874}
875
876
877/* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
878int
879ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp,
880 const Key **sign_ca_keys, u_int nsign_ca_keys)
881{
882 Buffer copy, sect;
883 struct ssh_krl *krl;
884 char timestamp[64];
885 int ret = -1, r, sig_seen;
886 Key *key = NULL, **ca_used = NULL;
887 u_char type, *blob;
888 u_int i, j, sig_off, sects_off, blen, format_version, nca_used = 0;
889
890 *krlp = NULL;
891 if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 ||
892 memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
893 debug3("%s: not a KRL", __func__);
894 /*
895 * Return success but a NULL *krlp here to signal that the
896 * file might be a simple list of keys.
897 */
898 return 0;
899 }
900
901 /* Take a copy of the KRL buffer so we can verify its signature later */
902 buffer_init(&copy);
903 buffer_append(&copy, buffer_ptr(buf), buffer_len(buf));
904
905 buffer_init(&sect);
906 buffer_consume(&copy, sizeof(KRL_MAGIC) - 1);
907
908 if ((krl = ssh_krl_init()) == NULL) {
909 error("%s: alloc failed", __func__);
910 goto out;
911 }
912
913 if (buffer_get_int_ret(&format_version, &copy) != 0) {
914 error("%s: KRL truncated", __func__);
915 goto out;
916 }
917 if (format_version != KRL_FORMAT_VERSION) {
918 error("%s: KRL unsupported format version %u",
919 __func__, format_version);
920 goto out;
921 }
922 if (buffer_get_int64_ret(&krl->krl_version, &copy) != 0 ||
923 buffer_get_int64_ret(&krl->generated_date, &copy) != 0 ||
924 buffer_get_int64_ret(&krl->flags, &copy) != 0 ||
925 buffer_get_string_ptr_ret(&copy, NULL) == NULL || /* reserved */
926 (krl->comment = buffer_get_cstring_ret(&copy, NULL)) == NULL) {
927 error("%s: buffer error", __func__);
928 goto out;
929 }
930
931 format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
932 debug("KRL version %llu generated at %s%s%s", krl->krl_version,
933 timestamp, *krl->comment ? ": " : "", krl->comment);
934
935 /*
936 * 1st pass: verify signatures, if any. This is done to avoid
937 * detailed parsing of data whose provenance is unverified.
938 */
939 sig_seen = 0;
940 sects_off = buffer_len(buf) - buffer_len(&copy);
941 while (buffer_len(&copy) > 0) {
942 if (buffer_get_char_ret(&type, &copy) != 0 ||
943 (blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
944 error("%s: buffer error", __func__);
945 goto out;
946 }
947 debug3("%s: first pass, section 0x%02x", __func__, type);
948 if (type != KRL_SECTION_SIGNATURE) {
949 if (sig_seen) {
950 error("KRL contains non-signature section "
951 "after signature");
952 goto out;
953 }
954 /* Not interested for now. */
955 continue;
956 }
957 sig_seen = 1;
958 /* First string component is the signing key */
959 if ((key = key_from_blob(blob, blen)) == NULL) {
960 error("%s: invalid signature key", __func__);
961 goto out;
962 }
963 sig_off = buffer_len(buf) - buffer_len(&copy);
964 /* Second string component is the signature itself */
965 if ((blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
966 error("%s: buffer error", __func__);
967 goto out;
968 }
969 /* Check signature over entire KRL up to this point */
970 if (key_verify(key, blob, blen,
971 buffer_ptr(buf), buffer_len(buf) - sig_off) == -1) {
972 error("bad signaure on KRL");
973 goto out;
974 }
975 /* Check if this key has already signed this KRL */
976 for (i = 0; i < nca_used; i++) {
977 if (key_equal(ca_used[i], key)) {
978 error("KRL signed more than once with "
979 "the same key");
980 goto out;
981 }
982 }
983 /* Record keys used to sign the KRL */
984 xrealloc(ca_used, nca_used + 1, sizeof(*ca_used));
985 ca_used[nca_used++] = key;
986 key = NULL;
987 break;
988 }
989
990 /*
991 * 2nd pass: parse and load the KRL, skipping the header to the point
992 * where the section start.
993 */
994 buffer_append(&copy, (u_char*)buffer_ptr(buf) + sects_off,
995 buffer_len(buf) - sects_off);
996 while (buffer_len(&copy) > 0) {
997 if (buffer_get_char_ret(&type, &copy) != 0 ||
998 (blob = buffer_get_string_ptr_ret(&copy, &blen)) == NULL) {
999 error("%s: buffer error", __func__);
1000 goto out;
1001 }
1002 debug3("%s: second pass, section 0x%02x", __func__, type);
1003 buffer_clear(&sect);
1004 buffer_append(&sect, blob, blen);
1005
1006 switch (type) {
1007 case KRL_SECTION_CERTIFICATES:
1008 if ((r = parse_revoked_certs(&sect, krl)) != 0)
1009 goto out;
1010 break;
1011 case KRL_SECTION_EXPLICIT_KEY:
1012 case KRL_SECTION_FINGERPRINT_SHA1:
1013 while (buffer_len(&sect) > 0) {
1014 if ((blob = buffer_get_string_ret(&sect,
1015 &blen)) == NULL) {
1016 error("%s: buffer error", __func__);
1017 goto out;
1018 }
1019 if (type == KRL_SECTION_FINGERPRINT_SHA1 &&
1020 blen != 20) {
1021 error("%s: bad SHA1 length", __func__);
1022 goto out;
1023 }
1024 if (revoke_blob(
1025 type == KRL_SECTION_EXPLICIT_KEY ?
1026 &krl->revoked_keys : &krl->revoked_sha1s,
1027 blob, blen) != 0)
1028 goto out; /* revoke_blob frees blob */
1029 }
1030 break;
1031 case KRL_SECTION_SIGNATURE:
1032 /* Handled above, but still need to stay in synch */
1033 buffer_clear(&sect);
1034 if ((blob = buffer_get_string_ptr_ret(&sect,
1035 &blen)) == NULL) {
1036 error("%s: buffer error", __func__);
1037 goto out;
1038 }
1039 break;
1040 default:
1041 error("Unsupported KRL section %u", type);
1042 goto out;
1043 }
1044 if (buffer_len(&sect) > 0) {
1045 error("KRL section contains unparsed data");
1046 goto out;
1047 }
1048 }
1049
1050 /* Check that the key(s) used to sign the KRL weren't revoked */
1051 sig_seen = 0;
1052 for (i = 0; i < nca_used; i++) {
1053 if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1054 sig_seen = 1;
1055 else {
1056 key_free(ca_used[i]);
1057 ca_used[i] = NULL;
1058 }
1059 }
1060 if (nca_used && !sig_seen) {
1061 error("All keys used to sign KRL were revoked");
1062 goto out;
1063 }
1064
1065 /* If we have CA keys, then verify that one was used to sign the KRL */
1066 if (sig_seen && nsign_ca_keys != 0) {
1067 sig_seen = 0;
1068 for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1069 for (j = 0; j < nca_used; j++) {
1070 if (ca_used[j] == NULL)
1071 continue;
1072 if (key_equal(ca_used[j], sign_ca_keys[i])) {
1073 sig_seen = 1;
1074 break;
1075 }
1076 }
1077 }
1078 if (!sig_seen) {
1079 error("KRL not signed with any trusted key");
1080 goto out;
1081 }
1082 }
1083
1084 *krlp = krl;
1085 ret = 0;
1086 out:
1087 if (ret != 0)
1088 ssh_krl_free(krl);
1089 for (i = 0; i < nca_used; i++) {
1090 if (ca_used[i] != NULL)
1091 key_free(ca_used[i]);
1092 }
1093 free(ca_used);
1094 if (key != NULL)
1095 key_free(key);
1096 buffer_free(&copy);
1097 buffer_free(&sect);
1098 return ret;
1099}
1100
1101/* Checks whether a given key/cert is revoked. Does not check its CA */
1102static int
1103is_key_revoked(struct ssh_krl *krl, const Key *key)
1104{
1105 struct revoked_blob rb, *erb;
1106 struct revoked_serial rs, *ers;
1107 struct revoked_key_id rki, *erki;
1108 struct revoked_certs *rc;
1109
1110 /* Check explicitly revoked hashes first */
1111 bzero(&rb, sizeof(rb));
1112 if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL)
1113 return -1;
1114 erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1115 free(rb.blob);
1116 if (erb != NULL) {
1117 debug("%s: revoked by key SHA1", __func__);
1118 return -1;
1119 }
1120
1121 /* Next, explicit keys */
1122 bzero(&rb, sizeof(rb));
1123 if (plain_key_blob(key, &rb.blob, &rb.len) != 0)
1124 return -1;
1125 erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1126 free(rb.blob);
1127 if (erb != NULL) {
1128 debug("%s: revoked by explicit key", __func__);
1129 return -1;
1130 }
1131
1132 if (!key_is_cert(key))
1133 return 0;
1134
1135 /* Check cert revocation */
1136 if (revoked_certs_for_ca_key(krl, key->cert->signature_key,
1137 &rc, 0) != 0)
1138 return -1;
1139 if (rc == NULL)
1140 return 0; /* No entry for this CA */
1141
1142 /* Check revocation by cert key ID */
1143 bzero(&rki, sizeof(rki));
1144 rki.key_id = key->cert->key_id;
1145 erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1146 if (erki != NULL) {
1147 debug("%s: revoked by key ID", __func__);
1148 return -1;
1149 }
1150
1151 /* Legacy cert formats lack serial numbers */
1152 if (key_cert_is_legacy(key))
1153 return 0;
1154
1155 bzero(&rs, sizeof(rs));
1156 rs.lo = rs.hi = key->cert->serial;
1157 ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1158 if (ers != NULL) {
1159 KRL_DBG(("%s: %llu matched %llu:%llu", __func__,
1160 key->cert->serial, ers->lo, ers->hi));
1161 debug("%s: revoked by serial", __func__);
1162 return -1;
1163 }
1164 KRL_DBG(("%s: %llu no match", __func__, key->cert->serial));
1165
1166 return 0;
1167}
1168
1169int
1170ssh_krl_check_key(struct ssh_krl *krl, const Key *key)
1171{
1172 int r;
1173
1174 debug2("%s: checking key", __func__);
1175 if ((r = is_key_revoked(krl, key)) != 0)
1176 return r;
1177 if (key_is_cert(key)) {
1178 debug2("%s: checking CA key", __func__);
1179 if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1180 return r;
1181 }
1182 debug3("%s: key okay", __func__);
1183 return 0;
1184}
1185
1186/* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */
1187int
1188ssh_krl_file_contains_key(const char *path, const Key *key)
1189{
1190 Buffer krlbuf;
1191 struct ssh_krl *krl;
1192 int revoked, fd;
1193
1194 if (path == NULL)
1195 return 0;
1196
1197 if ((fd = open(path, O_RDONLY)) == -1) {
1198 error("open %s: %s", path, strerror(errno));
1199 error("Revoked keys file not accessible - refusing public key "
1200 "authentication");
1201 return -1;
1202 }
1203 buffer_init(&krlbuf);
1204 if (!key_load_file(fd, path, &krlbuf)) {
1205 close(fd);
1206 buffer_free(&krlbuf);
1207 error("Revoked keys file not readable - refusing public key "
1208 "authentication");
1209 return -1;
1210 }
1211 close(fd);
1212 if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) {
1213 buffer_free(&krlbuf);
1214 error("Invalid KRL, refusing public key "
1215 "authentication");
1216 return -1;
1217 }
1218 buffer_free(&krlbuf);
1219 if (krl == NULL) {
1220 debug3("%s: %s is not a KRL file", __func__, path);
1221 return -2;
1222 }
1223 debug2("%s: checking KRL %s", __func__, path);
1224 revoked = ssh_krl_check_key(krl, key) != 0;
1225 ssh_krl_free(krl);
1226 return revoked ? -1 : 0;
1227}
generated by cgit v1.2.3 (git 2.39.1) at 2024-10-31 06:38:41 +0000