Annotation of src/usr.bin/ssh/krl.c, Revision 1.13
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:
1.13 ! djm 17: /* $OpenBSD: krl.c,v 1.12 2013/06/20 19:15:06 markus 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, "
1.11 djm 503: "selected 0x%02x%s", __func__, (long long unsigned)contig,
504: (long long unsigned)last_gap, (long long unsigned)next_gap, final,
505: (long long unsigned)cost_list, (long long unsigned)cost_range,
506: (long long unsigned)cost_bitmap,
507: (long long unsigned)cost_bitmap_restart, new_state,
1.1 djm 508: *force_new_section ? " restart" : "");
509: return new_state;
510: }
511:
512: /* Generate a KRL_SECTION_CERTIFICATES KRL section */
513: static int
514: revoked_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(§);
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__,
1.11 djm 543: (long long unsigned)rs->lo, (long long unsigned)rs->hi,
544: state);
1.1 djm 545:
546: /* Check contiguous length and gap to next section (if any) */
547: nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs);
548: final = nrs == NULL;
549: gap = nrs == NULL ? 0 : nrs->lo - rs->hi;
550: contig = 1 + (rs->hi - rs->lo);
551:
552: /* Choose next state based on these */
553: next_state = choose_next_state(state, contig, final,
554: state == 0 ? 0 : rs->lo - last, gap, &force_new_sect);
555:
556: /*
557: * If the current section is a range section or has a different
558: * type to the next section, then finish it off now.
559: */
560: if (state != 0 && (force_new_sect || next_state != state ||
561: state == KRL_SECTION_CERT_SERIAL_RANGE)) {
562: debug3("%s: finish state 0x%02x", __func__, state);
563: switch (state) {
564: case KRL_SECTION_CERT_SERIAL_LIST:
565: case KRL_SECTION_CERT_SERIAL_RANGE:
566: break;
567: case KRL_SECTION_CERT_SERIAL_BITMAP:
568: buffer_put_bignum2(§, bitmap);
569: BN_free(bitmap);
570: bitmap = NULL;
571: break;
572: }
573: buffer_put_char(buf, state);
574: buffer_put_string(buf,
575: buffer_ptr(§), buffer_len(§));
576: }
577:
578: /* If we are starting a new section then prepare it now */
579: if (next_state != state || force_new_sect) {
580: debug3("%s: start state 0x%02x", __func__, next_state);
581: state = next_state;
582: buffer_clear(§);
583: switch (state) {
584: case KRL_SECTION_CERT_SERIAL_LIST:
585: case KRL_SECTION_CERT_SERIAL_RANGE:
586: break;
587: case KRL_SECTION_CERT_SERIAL_BITMAP:
588: if ((bitmap = BN_new()) == NULL)
589: goto out;
590: bitmap_start = rs->lo;
591: buffer_put_int64(§, bitmap_start);
592: break;
593: }
594: }
595:
596: /* Perform section-specific processing */
597: switch (state) {
598: case KRL_SECTION_CERT_SERIAL_LIST:
1.3 djm 599: for (i = 0; i < contig; i++)
1.1 djm 600: buffer_put_int64(§, rs->lo + i);
601: break;
602: case KRL_SECTION_CERT_SERIAL_RANGE:
603: buffer_put_int64(§, rs->lo);
604: buffer_put_int64(§, rs->hi);
605: break;
606: case KRL_SECTION_CERT_SERIAL_BITMAP:
607: if (rs->lo - bitmap_start > INT_MAX) {
608: error("%s: insane bitmap gap", __func__);
609: goto out;
610: }
611: for (i = 0; i < contig; i++) {
612: if (BN_set_bit(bitmap,
613: rs->lo + i - bitmap_start) != 1)
614: goto out;
615: }
616: break;
617: }
618: last = rs->hi;
619: }
620: /* Flush the remaining section, if any */
621: if (state != 0) {
622: debug3("%s: serial final flush for state 0x%02x",
623: __func__, state);
624: switch (state) {
625: case KRL_SECTION_CERT_SERIAL_LIST:
626: case KRL_SECTION_CERT_SERIAL_RANGE:
627: break;
628: case KRL_SECTION_CERT_SERIAL_BITMAP:
629: buffer_put_bignum2(§, bitmap);
630: BN_free(bitmap);
631: bitmap = NULL;
632: break;
633: }
634: buffer_put_char(buf, state);
635: buffer_put_string(buf,
636: buffer_ptr(§), buffer_len(§));
637: }
638: debug3("%s: serial done ", __func__);
639:
640: /* Now output a section for any revocations by key ID */
641: buffer_clear(§);
642: RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) {
643: debug3("%s: key ID %s", __func__, rki->key_id);
644: buffer_put_cstring(§, rki->key_id);
645: }
646: if (buffer_len(§) != 0) {
647: buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID);
648: buffer_put_string(buf, buffer_ptr(§),
649: buffer_len(§));
650: }
651: r = 0;
652: out:
653: if (bitmap != NULL)
654: BN_free(bitmap);
655: buffer_free(§);
656: return r;
657: }
658:
659: int
660: ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys,
661: u_int nsign_keys)
662: {
663: int r = -1;
664: struct revoked_certs *rc;
665: struct revoked_blob *rb;
666: Buffer sect;
667: u_char *kblob = NULL, *sblob = NULL;
668: u_int klen, slen, i;
669:
670: if (krl->generated_date == 0)
671: krl->generated_date = time(NULL);
672:
673: buffer_init(§);
674:
675: /* Store the header */
676: buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1);
677: buffer_put_int(buf, KRL_FORMAT_VERSION);
678: buffer_put_int64(buf, krl->krl_version);
679: buffer_put_int64(buf, krl->generated_date);
680: buffer_put_int64(buf, krl->flags);
681: buffer_put_string(buf, NULL, 0);
682: buffer_put_cstring(buf, krl->comment ? krl->comment : "");
683:
684: /* Store sections for revoked certificates */
685: TAILQ_FOREACH(rc, &krl->revoked_certs, entry) {
686: if (revoked_certs_generate(rc, §) != 0)
687: goto out;
688: buffer_put_char(buf, KRL_SECTION_CERTIFICATES);
689: buffer_put_string(buf, buffer_ptr(§),
690: buffer_len(§));
691: }
692:
693: /* Finally, output sections for revocations by public key/hash */
694: buffer_clear(§);
695: RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) {
696: debug3("%s: key len %u ", __func__, rb->len);
697: buffer_put_string(§, rb->blob, rb->len);
698: }
699: if (buffer_len(§) != 0) {
700: buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY);
701: buffer_put_string(buf, buffer_ptr(§),
702: buffer_len(§));
703: }
704: buffer_clear(§);
705: RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) {
706: debug3("%s: hash len %u ", __func__, rb->len);
707: buffer_put_string(§, rb->blob, rb->len);
708: }
709: if (buffer_len(§) != 0) {
710: buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1);
711: buffer_put_string(buf, buffer_ptr(§),
712: buffer_len(§));
713: }
714:
715: for (i = 0; i < nsign_keys; i++) {
716: if (key_to_blob(sign_keys[i], &kblob, &klen) == 0)
717: goto out;
718:
719: debug3("%s: signature key len %u", __func__, klen);
720: buffer_put_char(buf, KRL_SECTION_SIGNATURE);
721: buffer_put_string(buf, kblob, klen);
722:
723: if (key_sign(sign_keys[i], &sblob, &slen,
724: buffer_ptr(buf), buffer_len(buf)) == -1)
725: goto out;
726: debug3("%s: signature sig len %u", __func__, slen);
727: buffer_put_string(buf, sblob, slen);
728: }
729:
730: r = 0;
731: out:
732: free(kblob);
733: free(sblob);
734: buffer_free(§);
735: return r;
736: }
737:
738: static void
739: format_timestamp(u_int64_t timestamp, char *ts, size_t nts)
740: {
741: time_t t;
742: struct tm *tm;
743:
744: t = timestamp;
745: tm = localtime(&t);
746: *ts = '\0';
747: strftime(ts, nts, "%Y%m%dT%H%M%S", tm);
748: }
749:
750: static int
751: parse_revoked_certs(Buffer *buf, struct ssh_krl *krl)
752: {
753: int ret = -1, nbits;
754: u_char type, *blob;
755: u_int blen;
756: Buffer subsect;
757: u_int64_t serial, serial_lo, serial_hi;
758: BIGNUM *bitmap = NULL;
759: char *key_id = NULL;
760: Key *ca_key = NULL;
761:
762: buffer_init(&subsect);
763:
764: if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL ||
765: buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */
766: error("%s: buffer error", __func__);
767: goto out;
768: }
769: if ((ca_key = key_from_blob(blob, blen)) == NULL)
770: goto out;
771:
772: while (buffer_len(buf) > 0) {
773: if (buffer_get_char_ret(&type, buf) != 0 ||
774: (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) {
775: error("%s: buffer error", __func__);
776: goto out;
777: }
778: buffer_clear(&subsect);
779: buffer_append(&subsect, blob, blen);
780: debug3("%s: subsection type 0x%02x", __func__, type);
781: /* buffer_dump(&subsect); */
782:
783: switch (type) {
784: case KRL_SECTION_CERT_SERIAL_LIST:
785: while (buffer_len(&subsect) > 0) {
786: if (buffer_get_int64_ret(&serial,
787: &subsect) != 0) {
788: error("%s: buffer error", __func__);
789: goto out;
790: }
791: if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
792: serial) != 0) {
793: error("%s: update failed", __func__);
794: goto out;
795: }
796: }
797: break;
798: case KRL_SECTION_CERT_SERIAL_RANGE:
799: if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
800: buffer_get_int64_ret(&serial_hi, &subsect) != 0) {
801: error("%s: buffer error", __func__);
802: goto out;
803: }
804: if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key,
805: serial_lo, serial_hi) != 0) {
806: error("%s: update failed", __func__);
807: goto out;
808: }
809: break;
810: case KRL_SECTION_CERT_SERIAL_BITMAP:
811: if ((bitmap = BN_new()) == NULL) {
812: error("%s: BN_new", __func__);
813: goto out;
814: }
815: if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 ||
816: buffer_get_bignum2_ret(&subsect, bitmap) != 0) {
817: error("%s: buffer error", __func__);
818: goto out;
819: }
820: if ((nbits = BN_num_bits(bitmap)) < 0) {
821: error("%s: bitmap bits < 0", __func__);
822: goto out;
823: }
824: for (serial = 0; serial < (u_int)nbits; serial++) {
825: if (serial > 0 && serial_lo + serial == 0) {
826: error("%s: bitmap wraps u64", __func__);
827: goto out;
828: }
829: if (!BN_is_bit_set(bitmap, serial))
830: continue;
831: if (ssh_krl_revoke_cert_by_serial(krl, ca_key,
832: serial_lo + serial) != 0) {
833: error("%s: update failed", __func__);
834: goto out;
835: }
836: }
837: BN_free(bitmap);
838: bitmap = NULL;
839: break;
840: case KRL_SECTION_CERT_KEY_ID:
841: while (buffer_len(&subsect) > 0) {
842: if ((key_id = buffer_get_cstring_ret(&subsect,
843: NULL)) == NULL) {
844: error("%s: buffer error", __func__);
845: goto out;
846: }
847: if (ssh_krl_revoke_cert_by_key_id(krl, ca_key,
848: key_id) != 0) {
849: error("%s: update failed", __func__);
850: goto out;
851: }
852: free(key_id);
853: key_id = NULL;
854: }
855: break;
856: default:
857: error("Unsupported KRL certificate section %u", type);
858: goto out;
859: }
860: if (buffer_len(&subsect) > 0) {
861: error("KRL certificate section contains unparsed data");
862: goto out;
863: }
864: }
865:
866: ret = 0;
867: out:
868: if (ca_key != NULL)
869: key_free(ca_key);
870: if (bitmap != NULL)
871: BN_free(bitmap);
872: free(key_id);
873: buffer_free(&subsect);
874: return ret;
875: }
876:
877:
878: /* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */
879: int
880: ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp,
881: const Key **sign_ca_keys, u_int nsign_ca_keys)
882: {
883: Buffer copy, sect;
884: struct ssh_krl *krl;
885: char timestamp[64];
886: int ret = -1, r, sig_seen;
887: Key *key = NULL, **ca_used = NULL;
1.12 markus 888: u_char type, *blob, *rdata = NULL;
889: u_int i, j, sig_off, sects_off, rlen, blen, format_version, nca_used;
1.1 djm 890:
1.12 markus 891: nca_used = 0;
1.1 djm 892: *krlp = NULL;
893: if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 ||
894: memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) {
895: debug3("%s: not a KRL", __func__);
896: /*
897: * Return success but a NULL *krlp here to signal that the
898: * file might be a simple list of keys.
899: */
900: return 0;
901: }
902:
903: /* Take a copy of the KRL buffer so we can verify its signature later */
904: buffer_init(©);
905: buffer_append(©, buffer_ptr(buf), buffer_len(buf));
906:
907: buffer_init(§);
908: buffer_consume(©, sizeof(KRL_MAGIC) - 1);
909:
910: if ((krl = ssh_krl_init()) == NULL) {
911: error("%s: alloc failed", __func__);
912: goto out;
913: }
914:
915: if (buffer_get_int_ret(&format_version, ©) != 0) {
916: error("%s: KRL truncated", __func__);
917: goto out;
918: }
919: if (format_version != KRL_FORMAT_VERSION) {
920: error("%s: KRL unsupported format version %u",
921: __func__, format_version);
922: goto out;
923: }
924: if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 ||
925: buffer_get_int64_ret(&krl->generated_date, ©) != 0 ||
926: buffer_get_int64_ret(&krl->flags, ©) != 0 ||
927: buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */
928: (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) {
929: error("%s: buffer error", __func__);
930: goto out;
931: }
932:
933: format_timestamp(krl->generated_date, timestamp, sizeof(timestamp));
1.11 djm 934: debug("KRL version %llu generated at %s%s%s",
935: (long long unsigned)krl->krl_version, timestamp,
936: *krl->comment ? ": " : "", krl->comment);
1.1 djm 937:
938: /*
939: * 1st pass: verify signatures, if any. This is done to avoid
940: * detailed parsing of data whose provenance is unverified.
941: */
942: sig_seen = 0;
943: sects_off = buffer_len(buf) - buffer_len(©);
944: while (buffer_len(©) > 0) {
945: if (buffer_get_char_ret(&type, ©) != 0 ||
946: (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
947: error("%s: buffer error", __func__);
948: goto out;
949: }
950: debug3("%s: first pass, section 0x%02x", __func__, type);
951: if (type != KRL_SECTION_SIGNATURE) {
952: if (sig_seen) {
953: error("KRL contains non-signature section "
954: "after signature");
955: goto out;
956: }
957: /* Not interested for now. */
958: continue;
959: }
960: sig_seen = 1;
961: /* First string component is the signing key */
962: if ((key = key_from_blob(blob, blen)) == NULL) {
963: error("%s: invalid signature key", __func__);
964: goto out;
965: }
966: sig_off = buffer_len(buf) - buffer_len(©);
967: /* Second string component is the signature itself */
968: if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
969: error("%s: buffer error", __func__);
970: goto out;
971: }
972: /* Check signature over entire KRL up to this point */
973: if (key_verify(key, blob, blen,
1.13 ! djm 974: buffer_ptr(buf), buffer_len(buf) - sig_off) != 1) {
1.1 djm 975: error("bad signaure on KRL");
976: goto out;
977: }
978: /* Check if this key has already signed this KRL */
979: for (i = 0; i < nca_used; i++) {
980: if (key_equal(ca_used[i], key)) {
981: error("KRL signed more than once with "
982: "the same key");
983: goto out;
984: }
985: }
986: /* Record keys used to sign the KRL */
1.9 djm 987: ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used));
1.1 djm 988: ca_used[nca_used++] = key;
989: key = NULL;
990: break;
991: }
992:
993: /*
994: * 2nd pass: parse and load the KRL, skipping the header to the point
995: * where the section start.
996: */
997: buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off,
998: buffer_len(buf) - sects_off);
999: while (buffer_len(©) > 0) {
1000: if (buffer_get_char_ret(&type, ©) != 0 ||
1001: (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) {
1002: error("%s: buffer error", __func__);
1003: goto out;
1004: }
1005: debug3("%s: second pass, section 0x%02x", __func__, type);
1006: buffer_clear(§);
1007: buffer_append(§, blob, blen);
1008:
1009: switch (type) {
1010: case KRL_SECTION_CERTIFICATES:
1011: if ((r = parse_revoked_certs(§, krl)) != 0)
1012: goto out;
1013: break;
1014: case KRL_SECTION_EXPLICIT_KEY:
1015: case KRL_SECTION_FINGERPRINT_SHA1:
1016: while (buffer_len(§) > 0) {
1.12 markus 1017: if ((rdata = buffer_get_string_ret(§,
1018: &rlen)) == NULL) {
1.1 djm 1019: error("%s: buffer error", __func__);
1020: goto out;
1021: }
1022: if (type == KRL_SECTION_FINGERPRINT_SHA1 &&
1.12 markus 1023: rlen != 20) {
1.1 djm 1024: error("%s: bad SHA1 length", __func__);
1025: goto out;
1026: }
1027: if (revoke_blob(
1028: type == KRL_SECTION_EXPLICIT_KEY ?
1029: &krl->revoked_keys : &krl->revoked_sha1s,
1.12 markus 1030: rdata, rlen) != 0)
1031: goto out;
1032: rdata = NULL; /* revoke_blob frees blob */
1.1 djm 1033: }
1034: break;
1035: case KRL_SECTION_SIGNATURE:
1036: /* Handled above, but still need to stay in synch */
1037: buffer_clear(§);
1.5 djm 1038: if ((blob = buffer_get_string_ptr_ret(©,
1.1 djm 1039: &blen)) == NULL) {
1040: error("%s: buffer error", __func__);
1041: goto out;
1042: }
1043: break;
1044: default:
1045: error("Unsupported KRL section %u", type);
1046: goto out;
1047: }
1048: if (buffer_len(§) > 0) {
1049: error("KRL section contains unparsed data");
1050: goto out;
1051: }
1052: }
1053:
1054: /* Check that the key(s) used to sign the KRL weren't revoked */
1055: sig_seen = 0;
1056: for (i = 0; i < nca_used; i++) {
1057: if (ssh_krl_check_key(krl, ca_used[i]) == 0)
1058: sig_seen = 1;
1059: else {
1060: key_free(ca_used[i]);
1061: ca_used[i] = NULL;
1062: }
1063: }
1064: if (nca_used && !sig_seen) {
1065: error("All keys used to sign KRL were revoked");
1066: goto out;
1067: }
1068:
1069: /* If we have CA keys, then verify that one was used to sign the KRL */
1070: if (sig_seen && nsign_ca_keys != 0) {
1071: sig_seen = 0;
1072: for (i = 0; !sig_seen && i < nsign_ca_keys; i++) {
1073: for (j = 0; j < nca_used; j++) {
1074: if (ca_used[j] == NULL)
1075: continue;
1076: if (key_equal(ca_used[j], sign_ca_keys[i])) {
1077: sig_seen = 1;
1078: break;
1079: }
1080: }
1081: }
1082: if (!sig_seen) {
1083: error("KRL not signed with any trusted key");
1084: goto out;
1085: }
1086: }
1087:
1088: *krlp = krl;
1089: ret = 0;
1090: out:
1091: if (ret != 0)
1092: ssh_krl_free(krl);
1093: for (i = 0; i < nca_used; i++) {
1094: if (ca_used[i] != NULL)
1095: key_free(ca_used[i]);
1096: }
1097: free(ca_used);
1.12 markus 1098: free(rdata);
1.1 djm 1099: if (key != NULL)
1100: key_free(key);
1101: buffer_free(©);
1102: buffer_free(§);
1103: return ret;
1104: }
1105:
1106: /* Checks whether a given key/cert is revoked. Does not check its CA */
1107: static int
1108: is_key_revoked(struct ssh_krl *krl, const Key *key)
1109: {
1110: struct revoked_blob rb, *erb;
1111: struct revoked_serial rs, *ers;
1112: struct revoked_key_id rki, *erki;
1113: struct revoked_certs *rc;
1114:
1115: /* Check explicitly revoked hashes first */
1116: bzero(&rb, sizeof(rb));
1117: if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL)
1118: return -1;
1119: erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb);
1120: free(rb.blob);
1121: if (erb != NULL) {
1122: debug("%s: revoked by key SHA1", __func__);
1123: return -1;
1124: }
1125:
1126: /* Next, explicit keys */
1127: bzero(&rb, sizeof(rb));
1128: if (plain_key_blob(key, &rb.blob, &rb.len) != 0)
1129: return -1;
1130: erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb);
1131: free(rb.blob);
1132: if (erb != NULL) {
1133: debug("%s: revoked by explicit key", __func__);
1134: return -1;
1135: }
1136:
1137: if (!key_is_cert(key))
1138: return 0;
1139:
1140: /* Check cert revocation */
1141: if (revoked_certs_for_ca_key(krl, key->cert->signature_key,
1142: &rc, 0) != 0)
1143: return -1;
1144: if (rc == NULL)
1145: return 0; /* No entry for this CA */
1146:
1147: /* Check revocation by cert key ID */
1148: bzero(&rki, sizeof(rki));
1149: rki.key_id = key->cert->key_id;
1150: erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki);
1151: if (erki != NULL) {
1152: debug("%s: revoked by key ID", __func__);
1153: return -1;
1154: }
1155:
1.8 djm 1156: /*
1157: * Legacy cert formats lack serial numbers. Zero serials numbers
1158: * are ignored (it's the default when the CA doesn't specify one).
1159: */
1160: if (key_cert_is_legacy(key) || key->cert->serial == 0)
1.1 djm 1161: return 0;
1162:
1163: bzero(&rs, sizeof(rs));
1164: rs.lo = rs.hi = key->cert->serial;
1165: ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs);
1166: if (ers != NULL) {
1167: KRL_DBG(("%s: %llu matched %llu:%llu", __func__,
1168: key->cert->serial, ers->lo, ers->hi));
1169: debug("%s: revoked by serial", __func__);
1170: return -1;
1171: }
1172: KRL_DBG(("%s: %llu no match", __func__, key->cert->serial));
1173:
1174: return 0;
1175: }
1176:
1177: int
1178: ssh_krl_check_key(struct ssh_krl *krl, const Key *key)
1179: {
1180: int r;
1181:
1182: debug2("%s: checking key", __func__);
1183: if ((r = is_key_revoked(krl, key)) != 0)
1184: return r;
1185: if (key_is_cert(key)) {
1186: debug2("%s: checking CA key", __func__);
1187: if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0)
1188: return r;
1189: }
1190: debug3("%s: key okay", __func__);
1191: return 0;
1192: }
1193:
1194: /* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */
1195: int
1196: ssh_krl_file_contains_key(const char *path, const Key *key)
1197: {
1198: Buffer krlbuf;
1199: struct ssh_krl *krl;
1200: int revoked, fd;
1201:
1202: if (path == NULL)
1203: return 0;
1204:
1205: if ((fd = open(path, O_RDONLY)) == -1) {
1206: error("open %s: %s", path, strerror(errno));
1207: error("Revoked keys file not accessible - refusing public key "
1208: "authentication");
1209: return -1;
1210: }
1211: buffer_init(&krlbuf);
1212: if (!key_load_file(fd, path, &krlbuf)) {
1213: close(fd);
1214: buffer_free(&krlbuf);
1215: error("Revoked keys file not readable - refusing public key "
1216: "authentication");
1217: return -1;
1218: }
1219: close(fd);
1220: if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) {
1221: buffer_free(&krlbuf);
1222: error("Invalid KRL, refusing public key "
1223: "authentication");
1224: return -1;
1225: }
1226: buffer_free(&krlbuf);
1227: if (krl == NULL) {
1228: debug3("%s: %s is not a KRL file", __func__, path);
1229: return -2;
1230: }
1231: debug2("%s: checking KRL %s", __func__, path);
1232: revoked = ssh_krl_check_key(krl, key) != 0;
1233: ssh_krl_free(krl);
1234: return revoked ? -1 : 0;
1235: }