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1.1 djm 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:
1.10 ! dtucker 17: /* $OpenBSD: krl.c,v 1.9 2013/01/27 10:06:12 djm Exp $ */
1.2 djm 18:
1.1 djm 19: #include <sys/types.h>
20: #include <sys/param.h>
21: #include <sys/tree.h>
22: #include <sys/queue.h>
23:
24: #include <errno.h>
25: #include <fcntl.h>
26: #include <limits.h>
27: #include <string.h>
28: #include <time.h>
29: #include <unistd.h>
30:
31: #include "buffer.h"
32: #include "key.h"
33: #include "authfile.h"
34: #include "misc.h"
35: #include "log.h"
36: #include "xmalloc.h"
37:
38: #include "krl.h"
39:
40: /* #define DEBUG_KRL */
41: #ifdef DEBUG_KRL
42: # define KRL_DBG(x) debug3 x
43: #else
44: # define KRL_DBG(x)
45: #endif
46:
47: /*
48: * Trees of revoked serial numbers, key IDs and keys. This allows
49: * quick searching, querying and producing lists in canonical order.
50: */
51:
52: /* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */
53: struct revoked_serial {
54: u_int64_t lo, hi;
55: RB_ENTRY(revoked_serial) tree_entry;
56: };
57: static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b);
58: RB_HEAD(revoked_serial_tree, revoked_serial);
59: RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp);
60:
61: /* Tree of key IDs */
62: struct revoked_key_id {
63: char *key_id;
64: RB_ENTRY(revoked_key_id) tree_entry;
65: };
66: static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b);
67: RB_HEAD(revoked_key_id_tree, revoked_key_id);
68: RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp);
69:
70: /* Tree of blobs (used for keys and fingerprints) */
71: struct revoked_blob {
72: u_char *blob;
73: u_int len;
74: RB_ENTRY(revoked_blob) tree_entry;
75: };
76: static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b);
77: RB_HEAD(revoked_blob_tree, revoked_blob);
78: RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp);
79:
80: /* Tracks revoked certs for a single CA */
81: struct revoked_certs {
82: Key *ca_key;
83: struct revoked_serial_tree revoked_serials;
84: struct revoked_key_id_tree revoked_key_ids;
85: TAILQ_ENTRY(revoked_certs) entry;
86: };
87: TAILQ_HEAD(revoked_certs_list, revoked_certs);
88:
89: struct ssh_krl {
90: u_int64_t krl_version;
91: u_int64_t generated_date;
92: u_int64_t flags;
93: char *comment;
94: struct revoked_blob_tree revoked_keys;
95: struct revoked_blob_tree revoked_sha1s;
96: struct revoked_certs_list revoked_certs;
97: };
98:
99: /* Return equal if a and b overlap */
100: static int
101: serial_cmp(struct revoked_serial *a, struct revoked_serial *b)
102: {
103: if (a->hi >= b->lo && a->lo <= b->hi)
104: return 0;
105: return a->lo < b->lo ? -1 : 1;
106: }
107:
108: static int
109: key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b)
110: {
111: return strcmp(a->key_id, b->key_id);
112: }
113:
114: static int
115: blob_cmp(struct revoked_blob *a, struct revoked_blob *b)
116: {
117: int r;
118:
119: if (a->len != b->len) {
120: if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0)
121: return r;
122: return a->len > b->len ? 1 : -1;
123: } else
124: return memcmp(a->blob, b->blob, a->len);
125: }
126:
127: struct ssh_krl *
128: ssh_krl_init(void)
129: {
130: struct ssh_krl *krl;
131:
132: if ((krl = calloc(1, sizeof(*krl))) == NULL)
133: return NULL;
134: RB_INIT(&krl->revoked_keys);
135: RB_INIT(&krl->revoked_sha1s);
136: TAILQ_INIT(&krl->revoked_certs);
137: return krl;
138: }
139:
140: static void
141: revoked_certs_free(struct revoked_certs *rc)
142: {
143: struct revoked_serial *rs, *trs;
144: struct revoked_key_id *rki, *trki;
145:
146: RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) {
147: RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs);
148: free(rs);
149: }
150: RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) {
151: RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki);
152: free(rki->key_id);
153: free(rki);
154: }
155: if (rc->ca_key != NULL)
156: key_free(rc->ca_key);
157: }
158:
159: void
160: ssh_krl_free(struct ssh_krl *krl)
161: {
162: struct revoked_blob *rb, *trb;
163: struct revoked_certs *rc, *trc;
164:
165: if (krl == NULL)
166: return;
167:
168: free(krl->comment);
169: RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) {
170: RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb);
171: free(rb->blob);
172: free(rb);
173: }
174: RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) {
175: RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb);
176: free(rb->blob);
177: free(rb);
178: }
179: TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) {
180: TAILQ_REMOVE(&krl->revoked_certs, rc, entry);
181: revoked_certs_free(rc);
182: }
183: }
184:
185: void
186: ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version)
187: {
188: krl->krl_version = version;
189: }
190:
191: void
192: ssh_krl_set_comment(struct ssh_krl *krl, const char *comment)
193: {
194: free(krl->comment);
195: if ((krl->comment = strdup(comment)) == NULL)
196: fatal("%s: strdup", __func__);
197: }
198:
199: /*
200: * Find the revoked_certs struct for a CA key. If allow_create is set then
201: * create a new one in the tree if one did not exist already.
202: */
203: static int
204: revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key,
205: struct revoked_certs **rcp, int allow_create)
206: {
207: struct revoked_certs *rc;
208:
209: *rcp = NULL;
210: TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
211: if (key_equal(rc->ca_key, ca_key)) {
212: *rcp = rc;
213: return 0;
214: }
215: }
216: if (!allow_create)
217: return 0;
218: /* If this CA doesn't exist in the list then add it now */
219: if ((rc = calloc(1, sizeof(*rc))) == NULL)
220: return -1;
221: if ((rc->ca_key = key_from_private(ca_key)) == NULL) {
222: free(rc);
223: return -1;
224: }
225: RB_INIT(&rc->revoked_serials);
226: RB_INIT(&rc->revoked_key_ids);
227: TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry);
228: debug3("%s: new CA %s", __func__, key_type(ca_key));
229: *rcp = rc;
230: return 0;
231: }
232:
233: static int
234: insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi)
235: {
236: struct revoked_serial rs, *ers, *crs, *irs;
237:
238: KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi));
239: bzero(&rs, sizeof(rs));
240: rs.lo = lo;
241: rs.hi = hi;
242: ers = RB_NFIND(revoked_serial_tree, rt, &rs);
243: if (ers == NULL || serial_cmp(ers, &rs) != 0) {
244: /* No entry matches. Just insert */
245: if ((irs = malloc(sizeof(rs))) == NULL)
246: return -1;
247: memcpy(irs, &rs, sizeof(*irs));
248: ers = RB_INSERT(revoked_serial_tree, rt, irs);
249: if (ers != NULL) {
250: KRL_DBG(("%s: bad: ers != NULL", __func__));
251: /* Shouldn't happen */
1.4 markus 252: free(irs);
1.1 djm 253: return -1;
254: }
255: ers = irs;
256: } else {
257: KRL_DBG(("%s: overlap found %llu:%llu", __func__,
258: ers->lo, ers->hi));
259: /*
260: * The inserted entry overlaps an existing one. Grow the
261: * existing entry.
262: */
263: if (ers->lo > lo)
264: ers->lo = lo;
265: if (ers->hi < hi)
266: ers->hi = hi;
267: }
268: /*
269: * The inserted or revised range might overlap or abut adjacent ones;
270: * coalesce as necessary.
271: */
272:
273: /* Check predecessors */
274: while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) {
275: KRL_DBG(("%s: pred %llu:%llu", __func__, crs->lo, crs->hi));
276: if (ers->lo != 0 && crs->hi < ers->lo - 1)
277: break;
278: /* This entry overlaps. */
279: if (crs->lo < ers->lo) {
280: ers->lo = crs->lo;
281: KRL_DBG(("%s: pred extend %llu:%llu", __func__,
282: ers->lo, ers->hi));
283: }
284: RB_REMOVE(revoked_serial_tree, rt, crs);
285: free(crs);
286: }
287: /* Check successors */
288: while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) {
289: KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi));
290: if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1)
291: break;
292: /* This entry overlaps. */
293: if (crs->hi > ers->hi) {
294: ers->hi = crs->hi;
295: KRL_DBG(("%s: succ extend %llu:%llu", __func__,
296: ers->lo, ers->hi));
297: }
298: RB_REMOVE(revoked_serial_tree, rt, crs);
299: free(crs);
300: }
301: KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi));
302: return 0;
303: }
304:
305: int
306: ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key,
307: u_int64_t serial)
308: {
309: return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial);
310: }
311:
312: int
313: ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key,
314: u_int64_t lo, u_int64_t hi)
315: {
316: struct revoked_certs *rc;
317:
318: if (lo > hi || lo == 0)
319: return -1;
320: if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0)
321: return -1;
322: return insert_serial_range(&rc->revoked_serials, lo, hi);
323: }
324:
325: int
326: ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key,
327: const char *key_id)
328: {
329: struct revoked_key_id *rki, *erki;
330: struct revoked_certs *rc;
331:
332: if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0)
333: return -1;
334:
335: debug3("%s: revoke %s", __func__, key_id);
336: if ((rki = calloc(1, sizeof(*rki))) == NULL ||
337: (rki->key_id = strdup(key_id)) == NULL) {
338: free(rki);
339: fatal("%s: strdup", __func__);
340: }
341: erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki);
342: if (erki != NULL) {
343: free(rki->key_id);
344: free(rki);
345: }
346: return 0;
347: }
348:
349: /* Convert "key" to a public key blob without any certificate information */
350: static int
351: plain_key_blob(const Key *key, u_char **blob, u_int *blen)
352: {
353: Key *kcopy;
354: int r;
355:
356: if ((kcopy = key_from_private(key)) == NULL)
357: return -1;
358: if (key_is_cert(kcopy)) {
359: if (key_drop_cert(kcopy) != 0) {
360: error("%s: key_drop_cert", __func__);
361: key_free(kcopy);
362: return -1;
363: }
364: }
365: r = key_to_blob(kcopy, blob, blen);
366: free(kcopy);
367: return r == 0 ? -1 : 0;
368: }
369:
370: /* Revoke a key blob. Ownership of blob is transferred to the tree */
371: static int
372: revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len)
373: {
374: struct revoked_blob *rb, *erb;
375:
376: if ((rb = calloc(1, sizeof(*rb))) == NULL)
377: return -1;
378: rb->blob = blob;
379: rb->len = len;
380: erb = RB_INSERT(revoked_blob_tree, rbt, rb);
381: if (erb != NULL) {
382: free(rb->blob);
383: free(rb);
384: }
385: return 0;
386: }
387:
388: int
389: ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key)
390: {
391: u_char *blob;
392: u_int len;
393:
394: debug3("%s: revoke type %s", __func__, key_type(key));
395: if (plain_key_blob(key, &blob, &len) != 0)
396: return -1;
397: return revoke_blob(&krl->revoked_keys, blob, len);
398: }
399:
400: int
401: ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key)
402: {
403: u_char *blob;
404: u_int len;
405:
406: debug3("%s: revoke type %s by sha1", __func__, key_type(key));
407: if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL)
408: return -1;
409: return revoke_blob(&krl->revoked_sha1s, blob, len);
410: }
411:
412: int
413: ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key)
414: {
415: if (!key_is_cert(key))
416: return ssh_krl_revoke_key_sha1(krl, key);
417:
418: if (key_cert_is_legacy(key) || key->cert->serial == 0) {
419: return ssh_krl_revoke_cert_by_key_id(krl,
420: key->cert->signature_key,
421: key->cert->key_id);
422: } else {
423: return ssh_krl_revoke_cert_by_serial(krl,
424: key->cert->signature_key,
425: key->cert->serial);
426: }
427: }
428:
429: /*
430: * Select a copact next section type to emit in a KRL based on the
431: * current section type, the run length of contiguous revoked serial
432: * numbers and the gaps from the last and to the next revoked serial.
433: * Applies a mostly-accurate bit cost model to select the section type
434: * that will minimise the size of the resultant KRL.
435: */
436: static int
437: choose_next_state(int current_state, u_int64_t contig, int final,
438: u_int64_t last_gap, u_int64_t next_gap, int *force_new_section)
439: {
440: int new_state;
441: u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart;
442:
443: /*
444: * Avoid unsigned overflows.
445: * The limits are high enough to avoid confusing the calculations.
446: */
447: contig = MIN(contig, 1ULL<<31);
448: last_gap = MIN(last_gap, 1ULL<<31);
449: next_gap = MIN(next_gap, 1ULL<<31);
450:
451: /*
452: * Calculate the cost to switch from the current state to candidates.
453: * NB. range sections only ever contain a single range, so their
454: * switching cost is independent of the current_state.
455: */
456: cost_list = cost_bitmap = cost_bitmap_restart = 0;
457: cost_range = 8;
458: switch (current_state) {
459: case KRL_SECTION_CERT_SERIAL_LIST:
460: cost_bitmap_restart = cost_bitmap = 8 + 64;
461: break;
462: case KRL_SECTION_CERT_SERIAL_BITMAP:
463: cost_list = 8;
464: cost_bitmap_restart = 8 + 64;
465: break;
466: case KRL_SECTION_CERT_SERIAL_RANGE:
467: case 0:
468: cost_bitmap_restart = cost_bitmap = 8 + 64;
469: cost_list = 8;
470: }
471:
472: /* Estimate base cost in bits of each section type */
473: cost_list += 64 * contig + (final ? 0 : 8+64);
474: cost_range += (2 * 64) + (final ? 0 : 8+64);
475: cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64));
476: cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64));
477:
478: /* Convert to byte costs for actual comparison */
479: cost_list = (cost_list + 7) / 8;
480: cost_bitmap = (cost_bitmap + 7) / 8;
481: cost_bitmap_restart = (cost_bitmap_restart + 7) / 8;
482: cost_range = (cost_range + 7) / 8;
483:
484: /* Now pick the best choice */
485: *force_new_section = 0;
486: new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
487: cost = cost_bitmap;
488: if (cost_range < cost) {
489: new_state = KRL_SECTION_CERT_SERIAL_RANGE;
490: cost = cost_range;
491: }
492: if (cost_list < cost) {
493: new_state = KRL_SECTION_CERT_SERIAL_LIST;
494: cost = cost_list;
495: }
496: if (cost_bitmap_restart < cost) {
497: new_state = KRL_SECTION_CERT_SERIAL_BITMAP;
498: *force_new_section = 1;
499: cost = cost_bitmap_restart;
500: }
501: debug3("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:"
502: "list %llu range %llu bitmap %llu new bitmap %llu, "
503: "selected 0x%02x%s", __func__, contig, last_gap, next_gap, final,
504: cost_list, cost_range, cost_bitmap, cost_bitmap_restart, new_state,
505: *force_new_section ? " restart" : "");
506: return new_state;
507: }
508:
509: /* Generate a KRL_SECTION_CERTIFICATES KRL section */
510: static int
511: revoked_certs_generate(struct revoked_certs *rc, Buffer *buf)
512: {
513: int final, force_new_sect, r = -1;
514: u_int64_t i, contig, gap, last = 0, bitmap_start = 0;
515: struct revoked_serial *rs, *nrs;
516: struct revoked_key_id *rki;
517: int next_state, state = 0;
518: Buffer sect;
519: u_char *kblob = NULL;
520: u_int klen;
521: BIGNUM *bitmap = NULL;
522:
523: /* Prepare CA scope key blob if we have one supplied */
524: if (key_to_blob(rc->ca_key, &kblob, &klen) == 0)
525: return -1;
526:
527: buffer_init(§);
528:
529: /* Store the header */
530: buffer_put_string(buf, kblob, klen);
531: buffer_put_string(buf, NULL, 0); /* Reserved */
532:
533: free(kblob);
534:
535: /* Store the revoked serials. */
536: for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials);
537: rs != NULL;
538: rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) {
539: debug3("%s: serial %llu:%llu state 0x%02x", __func__,
540: rs->lo, rs->hi, state);
541:
542: /* Check contiguous length and gap to next section (if any) */
543: nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
544: final = nrs == NULL;
545: gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
546: contig = 1 + (rs->hi - rs->lo);
547:
548: /* Choose next state based on these */
549: next_state = choose_next_state(state, contig, final,
550: state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
551:
552: /*
553: * If the current section is a range section or has a different
554: * type to the next section, then finish it off now.
555: */
556: if (state != 0 && (force_new_sect || next_state != state ||
557: state == KRL_SECTION_CERT_SERIAL_RANGE)) {
558: debug3("%s: finish state 0x%02x", __func__, state);
559: switch (state) {
560: case KRL_SECTION_CERT_SERIAL_LIST:
561: case KRL_SECTION_CERT_SERIAL_RANGE:
562: break;
563: case KRL_SECTION_CERT_SERIAL_BITMAP:
564: buffer_put_bignum2(§, bitmap);
565: BN_free(bitmap);
566: bitmap = NULL;
567: break;
568: }
569: buffer_put_char(buf, state);
570: buffer_put_string(buf,
571: buffer_ptr(§), buffer_len(§));
572: }
573:
574: /* If we are starting a new section then prepare it now */
575: if (next_state != state || force_new_sect) {
576: debug3("%s: start state 0x%02x", __func__, next_state);
577: state = next_state;
578: buffer_clear(§);
579: switch (state) {
580: case KRL_SECTION_CERT_SERIAL_LIST:
581: case KRL_SECTION_CERT_SERIAL_RANGE:
582: break;
583: case KRL_SECTION_CERT_SERIAL_BITMAP:
584: if ((bitmap = BN_new()) == NULL)
585: goto out;
586: bitmap_start = rs->lo;
587: buffer_put_int64(§, bitmap_start);
588: break;
589: }
590: }
591:
592: /* Perform section-specific processing */
593: switch (state) {
594: case KRL_SECTION_CERT_SERIAL_LIST:
1.3 djm 595: for (i = 0; i < contig; i++)
1.1 djm 596: buffer_put_int64(§, rs->lo + i);
597: break;
598: case KRL_SECTION_CERT_SERIAL_RANGE:
599: buffer_put_int64(§, rs->lo);
600: buffer_put_int64(§, rs->hi);
601: break;
602: case KRL_SECTION_CERT_SERIAL_BITMAP:
603: if (rs->lo - bitmap_start > INT_MAX) {
604: error("%s: insane bitmap gap", __func__);
605: goto out;
606: }
607: for (i = 0; i < contig; i++) {
608: if (BN_set_bit(bitmap,
609: rs->lo + i - bitmap_start) != 1)
610: goto out;
611: }
612: break;
613: }
614: last = rs->hi;
615: }
616: /* Flush the remaining section, if any */
617: if (state != 0) {
618: debug3("%s: serial final flush for state 0x%02x",
619: __func__, state);
620: switch (state) {
621: case KRL_SECTION_CERT_SERIAL_LIST:
622: case KRL_SECTION_CERT_SERIAL_RANGE:
623: break;
624: case KRL_SECTION_CERT_SERIAL_BITMAP:
625: buffer_put_bignum2(§, bitmap);
626: BN_free(bitmap);
627: bitmap = NULL;
628: break;
629: }
630: buffer_put_char(buf, state);
631: buffer_put_string(buf,
632: buffer_ptr(§), buffer_len(§));
633: }
634: debug3("%s: serial done ", __func__);
635:
636: /* Now output a section for any revocations by key ID */
637: buffer_clear(§);
638: RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
639: debug3("%s: key ID %s", __func__, rki->key_id);
640: buffer_put_cstring(§, rki->key_id);
641: }
642: if (buffer_len(§) != 0) {
643: buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID);
644: buffer_put_string(buf, buffer_ptr(§),
645: buffer_len(§));
646: }
647: r = 0;
648: out:
649: if (bitmap != NULL)
650: BN_free(bitmap);
651: buffer_free(§);
652: return r;
653: }
654:
655: int
656: ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys,
657: u_int nsign_keys)
658: {
659: int r = -1;
660: struct revoked_certs *rc;
661: struct revoked_blob *rb;
662: Buffer sect;
663: u_char *kblob = NULL, *sblob = NULL;
664: u_int klen, slen, i;
665:
666: if (krl->generated_date == 0)
667: krl->generated_date = time(NULL);
668:
669: buffer_init(§);
670:
671: /* Store the header */
672: buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1);
673: buffer_put_int(buf, KRL_FORMAT_VERSION);
674: buffer_put_int64(buf, krl->krl_version);
675: buffer_put_int64(buf, krl->generated_date);
676: buffer_put_int64(buf, krl->flags);
677: buffer_put_string(buf, NULL, 0);
678: buffer_put_cstring(buf, krl->comment ? krl->comment : "");
679:
680: /* Store sections for revoked certificates */
681: TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
682: if (revoked_certs_generate(rc, §) != 0)
683: goto out;
684: buffer_put_char(buf, KRL_SECTION_CERTIFICATES);
685: buffer_put_string(buf, buffer_ptr(§),
686: buffer_len(§));
687: }
688:
689: /* Finally, output sections for revocations by public key/hash */
690: buffer_clear(§);
691: RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
692: debug3("%s: key len %u ", __func__, rb->len);
693: buffer_put_string(§, rb->blob, rb->len);
694: }
695: if (buffer_len(§) != 0) {
696: buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY);
697: buffer_put_string(buf, buffer_ptr(§),
698: buffer_len(§));
699: }
700: buffer_clear(§);
701: RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
702: debug3("%s: hash len %u ", __func__, rb->len);
703: buffer_put_string(§, rb->blob, rb->len);
704: }
705: if (buffer_len(§) != 0) {
706: buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1);
707: buffer_put_string(buf, buffer_ptr(§),
708: buffer_len(§));
709: }
710:
711: for (i = 0; i < nsign_keys; i++) {
712: if (key_to_blob(sign_keys[i], &kblob, &klen) == 0)
713: goto out;
714:
715: debug3("%s: signature key len %u", __func__, klen);
716: buffer_put_char(buf, KRL_SECTION_SIGNATURE);
717: buffer_put_string(buf, kblob, klen);
718:
719: if (key_sign(sign_keys[i], &sblob, &slen,
720: buffer_ptr(buf), buffer_len(buf)) == -1)
721: goto out;
722: debug3("%s: signature sig len %u", __func__, slen);
723: buffer_put_string(buf, sblob, slen);
724: }
725:
726: r = 0;
727: out:
728: free(kblob);
729: free(sblob);
730: buffer_free(§);
731: return r;
732: }
733:
734: static void
735: format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
736: {
737: time_t t;
738: struct tm *tm;
739:
740: t = timestamp;
741: tm = localtime(&t);
742: *ts = '\0';
743: strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
744: }
745:
746: static int
747: parse_revoked_certs(Buffer *buf, struct ssh_krl *krl)
748: {
749: int ret = -1, nbits;
750: u_char type, *blob;
751: u_int blen;
752: Buffer subsect;
753: u_int64_t serial, serial_lo, serial_hi;
754: BIGNUM *bitmap = NULL;
755: char *key_id = NULL;
756: Key *ca_key = NULL;
757:
758: buffer_init(&subsect);
759:
760: if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL ||
761: buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */
762: error("%s: buffer error", __func__);
763: goto out;
764: }
765: if ((ca_key = key_from_blob(blob, blen)) == NULL)
766: goto out;
767:
768: while (buffer_len(buf) > 0) {
769: if (buffer_get_char_ret(&type, buf) != 0 ||
770: (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) {
771: error("%s: buffer error", __func__);
772: goto out;
773: }
774: buffer_clear(&subsect);
775: buffer_append(&subsect, blob, blen);
776: debug3("%s: subsection type 0x%02x", __func__, type);
777: /* buffer_dump(&subsect); */
778:
779: switch (type) {
780: case KRL_SECTION_CERT_SERIAL_LIST:
781: while (buffer_len(&subsect) > 0) {
782: if (buffer_get_int64_ret(&serial,
783: &subsect) != 0) {
784: error("%s: buffer error", __func__);
785: goto out;
786: }
787: if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
788: serial) != 0) {
789: error("%s: update failed", __func__);
790: goto out;
791: }
792: }
793: break;
794: case KRL_SECTION_CERT_SERIAL_RANGE:
795: if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
796: buffer_get_int64_ret(&serial_hi, &subsect) != 0) {
797: error("%s: buffer error", __func__);
798: goto out;
799: }
800: if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key,
801: serial_lo, serial_hi) != 0) {
802: error("%s: update failed", __func__);
803: goto out;
804: }
805: break;
806: case KRL_SECTION_CERT_SERIAL_BITMAP:
807: if ((bitmap = BN_new()) == NULL) {
808: error("%s: BN_new", __func__);
809: goto out;
810: }
811: if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
812: buffer_get_bignum2_ret(&subsect, bitmap) != 0) {
813: error("%s: buffer error", __func__);
814: goto out;
815: }
816: if ((nbits = BN_num_bits(bitmap)) < 0) {
817: error("%s: bitmap bits < 0", __func__);
818: goto out;
819: }
820: for (serial = 0; serial < (u_int)nbits; serial++) {
821: if (serial > 0 && serial_lo + serial == 0) {
822: error("%s: bitmap wraps u64", __func__);
823: goto out;
824: }
825: if (!BN_is_bit_set(bitmap, serial))
826: continue;
827: if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
828: serial_lo + serial) != 0) {
829: error("%s: update failed", __func__);
830: goto out;
831: }
832: }
833: BN_free(bitmap);
834: bitmap = NULL;
835: break;
836: case KRL_SECTION_CERT_KEY_ID:
837: while (buffer_len(&subsect) > 0) {
838: if ((key_id = buffer_get_cstring_ret(&subsect,
839: NULL)) == NULL) {
840: error("%s: buffer error", __func__);
841: goto out;
842: }
843: if (ssh_krl_revoke_cert_by_key_id(krl, ca_key,
844: key_id) != 0) {
845: error("%s: update failed", __func__);
846: goto out;
847: }
848: free(key_id);
849: key_id = NULL;
850: }
851: break;
852: default:
853: error("Unsupported KRL certificate section %u", type);
854: goto out;
855: }
856: if (buffer_len(&subsect) > 0) {
857: error("KRL certificate section contains unparsed data");
858: goto out;
859: }
860: }
861:
862: ret = 0;
863: out:
864: if (ca_key != NULL)
865: key_free(ca_key);
866: if (bitmap != NULL)
867: BN_free(bitmap);
868: free(key_id);
869: buffer_free(&subsect);
870: return ret;
871: }
872:
873:
874: /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
875: int
876: ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp,
877: const Key **sign_ca_keys, u_int nsign_ca_keys)
878: {
879: Buffer copy, sect;
880: struct ssh_krl *krl;
881: char timestamp[64];
882: int ret = -1, r, sig_seen;
883: Key *key = NULL, **ca_used = NULL;
884: u_char type, *blob;
885: u_int i, j, sig_off, sects_off, blen, format_version, nca_used = 0;
886:
887: *krlp = NULL;
888: if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 ||
889: memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
890: debug3("%s: not a KRL", __func__);
891: /*
892: * Return success but a NULL *krlp here to signal that the
893: * file might be a simple list of keys.
894: */
895: return 0;
896: }
897:
898: /* Take a copy of the KRL buffer so we can verify its signature later */
899: buffer_init(©);
900: buffer_append(©, buffer_ptr(buf), buffer_len(buf));
901:
902: buffer_init(§);
903: buffer_consume(©, sizeof(KRL_MAGIC) - 1);
904:
905: if ((krl = ssh_krl_init()) == NULL) {
906: error("%s: alloc failed", __func__);
907: goto out;
908: }
909:
910: if (buffer_get_int_ret(&format_version, ©) != 0) {
911: error("%s: KRL truncated", __func__);
912: goto out;
913: }
914: if (format_version != KRL_FORMAT_VERSION) {
915: error("%s: KRL unsupported format version %u",
916: __func__, format_version);
917: goto out;
918: }
919: if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 ||
920: buffer_get_int64_ret(&krl->generated_date, ©) != 0 ||
921: buffer_get_int64_ret(&krl->flags, ©) != 0 ||
922: buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */
923: (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) {
924: error("%s: buffer error", __func__);
925: goto out;
926: }
927:
928: format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
929: debug("KRL version %llu generated at %s%s%s", krl->krl_version,
930: timestamp, *krl->comment ? ": " : "", krl->comment);
931:
932: /*
933: * 1st pass: verify signatures, if any. This is done to avoid
934: * detailed parsing of data whose provenance is unverified.
935: */
936: sig_seen = 0;
937: sects_off = buffer_len(buf) - buffer_len(©);
938: while (buffer_len(©) > 0) {
939: if (buffer_get_char_ret(&type, ©) != 0 ||
940: (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
941: error("%s: buffer error", __func__);
942: goto out;
943: }
944: debug3("%s: first pass, section 0x%02x", __func__, type);
945: if (type != KRL_SECTION_SIGNATURE) {
946: if (sig_seen) {
947: error("KRL contains non-signature section "
948: "after signature");
949: goto out;
950: }
951: /* Not interested for now. */
952: continue;
953: }
954: sig_seen = 1;
955: /* First string component is the signing key */
956: if ((key = key_from_blob(blob, blen)) == NULL) {
957: error("%s: invalid signature key", __func__);
958: goto out;
959: }
960: sig_off = buffer_len(buf) - buffer_len(©);
961: /* Second string component is the signature itself */
962: if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
963: error("%s: buffer error", __func__);
964: goto out;
965: }
966: /* Check signature over entire KRL up to this point */
967: if (key_verify(key, blob, blen,
968: buffer_ptr(buf), buffer_len(buf) - sig_off) == -1) {
969: error("bad signaure on KRL");
970: goto out;
971: }
972: /* Check if this key has already signed this KRL */
973: for (i = 0; i < nca_used; i++) {
974: if (key_equal(ca_used[i], key)) {
975: error("KRL signed more than once with "
976: "the same key");
977: goto out;
978: }
979: }
980: /* Record keys used to sign the KRL */
1.9 djm 981: ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used));
1.1 djm 982: ca_used[nca_used++] = key;
983: key = NULL;
984: break;
985: }
986:
987: /*
988: * 2nd pass: parse and load the KRL, skipping the header to the point
989: * where the section start.
990: */
991: buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off,
992: buffer_len(buf) - sects_off);
993: while (buffer_len(©) > 0) {
994: if (buffer_get_char_ret(&type, ©) != 0 ||
995: (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
996: error("%s: buffer error", __func__);
997: goto out;
998: }
999: debug3("%s: second pass, section 0x%02x", __func__, type);
1000: buffer_clear(§);
1001: buffer_append(§, blob, blen);
1002:
1003: switch (type) {
1004: case KRL_SECTION_CERTIFICATES:
1005: if ((r = parse_revoked_certs(§, krl)) != 0)
1006: goto out;
1007: break;
1008: case KRL_SECTION_EXPLICIT_KEY:
1009: case KRL_SECTION_FINGERPRINT_SHA1:
1010: while (buffer_len(§) > 0) {
1011: if ((blob = buffer_get_string_ret(§,
1012: &blen)) == NULL) {
1013: error("%s: buffer error", __func__);
1014: goto out;
1015: }
1016: if (type == KRL_SECTION_FINGERPRINT_SHA1 &&
1017: blen != 20) {
1018: error("%s: bad SHA1 length", __func__);
1019: goto out;
1020: }
1021: if (revoke_blob(
1022: type == KRL_SECTION_EXPLICIT_KEY ?
1023: &krl->revoked_keys : &krl->revoked_sha1s,
1024: blob, blen) != 0)
1025: goto out; /* revoke_blob frees blob */
1026: }
1027: break;
1028: case KRL_SECTION_SIGNATURE:
1029: /* Handled above, but still need to stay in synch */
1030: buffer_clear(§);
1.5 djm 1031: if ((blob = buffer_get_string_ptr_ret(©,
1.1 djm 1032: &blen)) == NULL) {
1033: error("%s: buffer error", __func__);
1034: goto out;
1035: }
1036: break;
1037: default:
1038: error("Unsupported KRL section %u", type);
1039: goto out;
1040: }
1041: if (buffer_len(§) > 0) {
1042: error("KRL section contains unparsed data");
1043: goto out;
1044: }
1045: }
1046:
1047: /* Check that the key(s) used to sign the KRL weren't revoked */
1048: sig_seen = 0;
1049: for (i = 0; i < nca_used; i++) {
1050: if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1051: sig_seen = 1;
1052: else {
1053: key_free(ca_used[i]);
1054: ca_used[i] = NULL;
1055: }
1056: }
1057: if (nca_used && !sig_seen) {
1058: error("All keys used to sign KRL were revoked");
1059: goto out;
1060: }
1061:
1062: /* If we have CA keys, then verify that one was used to sign the KRL */
1063: if (sig_seen && nsign_ca_keys != 0) {
1064: sig_seen = 0;
1065: for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1066: for (j = 0; j < nca_used; j++) {
1067: if (ca_used[j] == NULL)
1068: continue;
1069: if (key_equal(ca_used[j], sign_ca_keys[i])) {
1070: sig_seen = 1;
1071: break;
1072: }
1073: }
1074: }
1075: if (!sig_seen) {
1076: error("KRL not signed with any trusted key");
1077: goto out;
1078: }
1079: }
1080:
1081: *krlp = krl;
1082: ret = 0;
1083: out:
1084: if (ret != 0)
1085: ssh_krl_free(krl);
1086: for (i = 0; i < nca_used; i++) {
1087: if (ca_used[i] != NULL)
1088: key_free(ca_used[i]);
1089: }
1090: free(ca_used);
1091: if (key != NULL)
1092: key_free(key);
1093: buffer_free(©);
1094: buffer_free(§);
1095: return ret;
1096: }
1097:
1098: /* Checks whether a given key/cert is revoked. Does not check its CA */
1099: static int
1100: is_key_revoked(struct ssh_krl *krl, const Key *key)
1101: {
1102: struct revoked_blob rb, *erb;
1103: struct revoked_serial rs, *ers;
1104: struct revoked_key_id rki, *erki;
1105: struct revoked_certs *rc;
1106:
1107: /* Check explicitly revoked hashes first */
1108: bzero(&rb, sizeof(rb));
1109: if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL)
1110: return -1;
1111: erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1112: free(rb.blob);
1113: if (erb != NULL) {
1114: debug("%s: revoked by key SHA1", __func__);
1115: return -1;
1116: }
1117:
1118: /* Next, explicit keys */
1119: bzero(&rb, sizeof(rb));
1120: if (plain_key_blob(key, &rb.blob, &rb.len) != 0)
1121: return -1;
1122: erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1123: free(rb.blob);
1124: if (erb != NULL) {
1125: debug("%s: revoked by explicit key", __func__);
1126: return -1;
1127: }
1128:
1129: if (!key_is_cert(key))
1130: return 0;
1131:
1132: /* Check cert revocation */
1133: if (revoked_certs_for_ca_key(krl, key->cert->signature_key,
1134: &rc, 0) != 0)
1135: return -1;
1136: if (rc == NULL)
1137: return 0; /* No entry for this CA */
1138:
1139: /* Check revocation by cert key ID */
1140: bzero(&rki, sizeof(rki));
1141: rki.key_id = key->cert->key_id;
1142: erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1143: if (erki != NULL) {
1144: debug("%s: revoked by key ID", __func__);
1145: return -1;
1146: }
1147:
1.8 djm 1148: /*
1149: * Legacy cert formats lack serial numbers. Zero serials numbers
1150: * are ignored (it's the default when the CA doesn't specify one).
1151: */
1152: if (key_cert_is_legacy(key) || key->cert->serial == 0)
1.1 djm 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:
1169: int
1170: ssh_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 */
1187: int
1188: ssh_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: }