1/*-
2 * Copyright (c) 2002 Poul-Henning Kamp
3 * Copyright (c) 2002 Networks Associates Technology, Inc.
4 * All rights reserved.
5 *
6 * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7 * and NAI Labs, the Security Research Division of Network Associates, Inc.
8 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9 * DARPA CHATS research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
| 1/*-
2 * Copyright (c) 2002 Poul-Henning Kamp
3 * Copyright (c) 2002 Networks Associates Technology, Inc.
4 * All rights reserved.
5 *
6 * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7 * and NAI Labs, the Security Research Division of Network Associates, Inc.
8 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9 * DARPA CHATS research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
|
33 *
34 * This source file contains the functions responsible for the crypto, keying
35 * and mapping operations on the I/O requests.
36 *
37 */
38
39#include <sys/param.h>
40#include <sys/stdint.h>
41#include <sys/bio.h>
42#include <sys/lock.h>
43#include <sys/mutex.h>
44#include <sys/queue.h>
45#include <sys/malloc.h>
46#include <sys/libkern.h>
47#include <sys/md5.h>
48
49#include <crypto/rijndael/rijndael.h>
50#include <crypto/sha2/sha2.h>
51
52#include <geom/geom.h>
53#include <geom/bde/g_bde.h>
54
55
56/*
57 * Derive kkey from mkey + sector offset.
58 *
59 * Security objective: Derive a potentially very large number of distinct skeys
60 * from the comparatively small key material in our mkey, in such a way that
61 * if one, more or even many of the kkeys are compromised, this does not
62 * significantly help an attack on other kkeys and in particular does not
63 * weaken or compromised the mkey.
64 *
65 * First we MD5 hash the sectornumber with the salt from the lock sector.
66 * The salt prevents the precalculation and statistical analysis of the MD5
67 * output which would be possible if we only gave it the sectornumber.
68 *
69 * The MD5 hash is used to pick out 16 bytes from the masterkey, which
70 * are then hashed with MD5 together with the sector number.
71 *
72 * The resulting MD5 hash is the kkey.
73 */
74
75static void
76g_bde_kkey(struct g_bde_softc *sc, keyInstance *ki, int dir, off_t sector)
77{
78 u_int t;
79 MD5_CTX ct;
80 u_char buf[16];
81 u_char buf2[8];
82
83 /* We have to be architecture neutral */
84 g_enc_le8(buf2, sector);
85
86 MD5Init(&ct);
87 MD5Update(&ct, sc->key.salt, 8);
88 MD5Update(&ct, buf2, sizeof buf2);
89 MD5Update(&ct, sc->key.salt + 8, 8);
90 MD5Final(buf, &ct);
91
92 MD5Init(&ct);
93 for (t = 0; t < 16; t++) {
94 MD5Update(&ct, &sc->key.mkey[buf[t]], 1);
95 if (t == 8)
96 MD5Update(&ct, buf2, sizeof buf2);
97 }
98 bzero(buf2, sizeof buf2);
99 MD5Final(buf, &ct);
100 bzero(&ct, sizeof ct);
101 AES_makekey(ki, dir, G_BDE_KKEYBITS, buf);
102 bzero(buf, sizeof buf);
103}
104
105/*
106 * Encryption work for read operation.
107 *
108 * Security objective: Find the kkey, find the skey, decrypt the sector data.
109 */
110
111void
112g_bde_crypt_read(struct g_bde_work *wp)
113{
114 struct g_bde_softc *sc;
115 u_char *d;
116 u_int n;
117 off_t o;
118 u_char skey[G_BDE_SKEYLEN];
119 keyInstance ki;
120 cipherInstance ci;
121
122
123 AES_init(&ci);
124 sc = wp->softc;
125 o = 0;
126 for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
127 d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
128 g_bde_kkey(sc, &ki, DIR_DECRYPT, wp->offset + o);
129 AES_decrypt(&ci, &ki, d, skey, sizeof skey);
130 d = (u_char *)wp->data + o;
131 AES_makekey(&ki, DIR_DECRYPT, G_BDE_SKEYBITS, skey);
132 AES_decrypt(&ci, &ki, d, d, sc->sectorsize);
133 }
134 bzero(skey, sizeof skey);
135 bzero(&ci, sizeof ci);
136 bzero(&ki, sizeof ci);
137}
138
139/*
140 * Encryption work for write operation.
141 *
142 * Security objective: Create random skey, encrypt sector data,
143 * encrypt skey with the kkey.
144 */
145
146void
147g_bde_crypt_write(struct g_bde_work *wp)
148{
149 u_char *s, *d;
150 struct g_bde_softc *sc;
151 u_int n;
152 off_t o;
153 u_char skey[G_BDE_SKEYLEN];
154 keyInstance ki;
155 cipherInstance ci;
156
157 sc = wp->softc;
158 AES_init(&ci);
159 o = 0;
160 for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
161
162 s = (u_char *)wp->data + o;
163 d = (u_char *)wp->sp->data + o;
164 arc4rand(&skey, sizeof skey, 0);
165 AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
166 AES_encrypt(&ci, &ki, s, d, sc->sectorsize);
167
168 d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
169 g_bde_kkey(sc, &ki, DIR_ENCRYPT, wp->offset + o);
170 AES_encrypt(&ci, &ki, skey, d, sizeof skey);
171 bzero(skey, sizeof skey);
172 }
173 bzero(skey, sizeof skey);
174 bzero(&ci, sizeof ci);
175 bzero(&ki, sizeof ci);
176}
177
178/*
179 * Encryption work for delete operation.
180 *
181 * Security objective: Write random data to the sectors.
182 *
183 * XXX: At a hit in performance we would trash the encrypted skey as well.
184 * XXX: This would add frustration to the cleaning lady attack by making
185 * XXX: deletes look like writes.
186 */
187
188void
189g_bde_crypt_delete(struct g_bde_work *wp)
190{
191 struct g_bde_softc *sc;
192 u_char *d;
193 off_t o;
194 u_char skey[G_BDE_SKEYLEN];
195 keyInstance ki;
196 cipherInstance ci;
197
198 sc = wp->softc;
199 d = wp->sp->data;
200 AES_init(&ci);
201 /*
202 * Do not unroll this loop!
203 * Our zone may be significantly wider than the amount of random
204 * bytes arc4rand likes to give in one reseeding, whereas our
205 * sectorsize is far more likely to be in the same range.
206 */
207 for (o = 0; o < wp->length; o += sc->sectorsize) {
208 arc4rand(d, sc->sectorsize, 0);
209 arc4rand(&skey, sizeof skey, 0);
210 AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
211 AES_encrypt(&ci, &ki, d, d, sc->sectorsize);
212 d += sc->sectorsize;
213 }
214 /*
215 * Having written a long random sequence to disk here, we want to
216 * force a reseed, to avoid weakening the next time we use random
217 * data for something important.
218 */
219 arc4rand(&o, sizeof o, 1);
220}
221
222/*
223 * Calculate the total payload size of the encrypted device.
224 *
225 * Security objectives: none.
226 *
227 * This function needs to agree with g_bde_map_sector() about things.
228 */
229
230uint64_t
231g_bde_max_sector(struct g_bde_key *kp)
232{
233 uint64_t maxsect;
234
235 maxsect = kp->media_width;
236 maxsect /= kp->zone_width;
237 maxsect *= kp->zone_cont;
238 return (maxsect);
239}
240
241/*
242 * Convert an unencrypted side offset to offsets on the encrypted side.
243 *
244 * Security objective: Make it harder to identify what sectors contain what
245 * on a "cold" disk image.
246 *
247 * We do this by adding the "keyoffset" from the lock to the physical sector
248 * number modulus the available number of sectors. Since all physical sectors
249 * presumably look the same cold, this will do.
250 *
251 * As part of the mapping we have to skip the lock sectors which we know
252 * the physical address off. We also truncate the work packet, respecting
253 * zone boundaries and lock sectors, so that we end up with a sequence of
254 * sectors which are physically contiguous.
255 *
256 * Shuffling things further is an option, but the incremental frustration is
257 * not currently deemed worth the run-time performance hit resulting from the
258 * increased number of disk arm movements it would incur.
259 *
260 * This function offers nothing but a trivial diversion for an attacker able
261 * to do "the cleaning lady attack" in its current static mapping form.
262 */
263
264void
265g_bde_map_sector(struct g_bde_work *wp)
266{
267
268 u_int zone, zoff, u, len;
269 uint64_t ko;
270 struct g_bde_softc *sc;
271 struct g_bde_key *kp;
272
273 sc = wp->softc;
274 kp = &sc->key;
275
276 /* find which zone and the offset in it */
277 zone = wp->offset / kp->zone_cont;
278 zoff = wp->offset % kp->zone_cont;
279
280 /* Calculate the offset of the key in the key sector */
281 wp->ko = (zoff / kp->sectorsize) * G_BDE_SKEYLEN;
282
283 /* restrict length to that zone */
284 len = kp->zone_cont - zoff;
| 33 *
34 * This source file contains the functions responsible for the crypto, keying
35 * and mapping operations on the I/O requests.
36 *
37 */
38
39#include <sys/param.h>
40#include <sys/stdint.h>
41#include <sys/bio.h>
42#include <sys/lock.h>
43#include <sys/mutex.h>
44#include <sys/queue.h>
45#include <sys/malloc.h>
46#include <sys/libkern.h>
47#include <sys/md5.h>
48
49#include <crypto/rijndael/rijndael.h>
50#include <crypto/sha2/sha2.h>
51
52#include <geom/geom.h>
53#include <geom/bde/g_bde.h>
54
55
56/*
57 * Derive kkey from mkey + sector offset.
58 *
59 * Security objective: Derive a potentially very large number of distinct skeys
60 * from the comparatively small key material in our mkey, in such a way that
61 * if one, more or even many of the kkeys are compromised, this does not
62 * significantly help an attack on other kkeys and in particular does not
63 * weaken or compromised the mkey.
64 *
65 * First we MD5 hash the sectornumber with the salt from the lock sector.
66 * The salt prevents the precalculation and statistical analysis of the MD5
67 * output which would be possible if we only gave it the sectornumber.
68 *
69 * The MD5 hash is used to pick out 16 bytes from the masterkey, which
70 * are then hashed with MD5 together with the sector number.
71 *
72 * The resulting MD5 hash is the kkey.
73 */
74
75static void
76g_bde_kkey(struct g_bde_softc *sc, keyInstance *ki, int dir, off_t sector)
77{
78 u_int t;
79 MD5_CTX ct;
80 u_char buf[16];
81 u_char buf2[8];
82
83 /* We have to be architecture neutral */
84 g_enc_le8(buf2, sector);
85
86 MD5Init(&ct);
87 MD5Update(&ct, sc->key.salt, 8);
88 MD5Update(&ct, buf2, sizeof buf2);
89 MD5Update(&ct, sc->key.salt + 8, 8);
90 MD5Final(buf, &ct);
91
92 MD5Init(&ct);
93 for (t = 0; t < 16; t++) {
94 MD5Update(&ct, &sc->key.mkey[buf[t]], 1);
95 if (t == 8)
96 MD5Update(&ct, buf2, sizeof buf2);
97 }
98 bzero(buf2, sizeof buf2);
99 MD5Final(buf, &ct);
100 bzero(&ct, sizeof ct);
101 AES_makekey(ki, dir, G_BDE_KKEYBITS, buf);
102 bzero(buf, sizeof buf);
103}
104
105/*
106 * Encryption work for read operation.
107 *
108 * Security objective: Find the kkey, find the skey, decrypt the sector data.
109 */
110
111void
112g_bde_crypt_read(struct g_bde_work *wp)
113{
114 struct g_bde_softc *sc;
115 u_char *d;
116 u_int n;
117 off_t o;
118 u_char skey[G_BDE_SKEYLEN];
119 keyInstance ki;
120 cipherInstance ci;
121
122
123 AES_init(&ci);
124 sc = wp->softc;
125 o = 0;
126 for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
127 d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
128 g_bde_kkey(sc, &ki, DIR_DECRYPT, wp->offset + o);
129 AES_decrypt(&ci, &ki, d, skey, sizeof skey);
130 d = (u_char *)wp->data + o;
131 AES_makekey(&ki, DIR_DECRYPT, G_BDE_SKEYBITS, skey);
132 AES_decrypt(&ci, &ki, d, d, sc->sectorsize);
133 }
134 bzero(skey, sizeof skey);
135 bzero(&ci, sizeof ci);
136 bzero(&ki, sizeof ci);
137}
138
139/*
140 * Encryption work for write operation.
141 *
142 * Security objective: Create random skey, encrypt sector data,
143 * encrypt skey with the kkey.
144 */
145
146void
147g_bde_crypt_write(struct g_bde_work *wp)
148{
149 u_char *s, *d;
150 struct g_bde_softc *sc;
151 u_int n;
152 off_t o;
153 u_char skey[G_BDE_SKEYLEN];
154 keyInstance ki;
155 cipherInstance ci;
156
157 sc = wp->softc;
158 AES_init(&ci);
159 o = 0;
160 for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
161
162 s = (u_char *)wp->data + o;
163 d = (u_char *)wp->sp->data + o;
164 arc4rand(&skey, sizeof skey, 0);
165 AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
166 AES_encrypt(&ci, &ki, s, d, sc->sectorsize);
167
168 d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
169 g_bde_kkey(sc, &ki, DIR_ENCRYPT, wp->offset + o);
170 AES_encrypt(&ci, &ki, skey, d, sizeof skey);
171 bzero(skey, sizeof skey);
172 }
173 bzero(skey, sizeof skey);
174 bzero(&ci, sizeof ci);
175 bzero(&ki, sizeof ci);
176}
177
178/*
179 * Encryption work for delete operation.
180 *
181 * Security objective: Write random data to the sectors.
182 *
183 * XXX: At a hit in performance we would trash the encrypted skey as well.
184 * XXX: This would add frustration to the cleaning lady attack by making
185 * XXX: deletes look like writes.
186 */
187
188void
189g_bde_crypt_delete(struct g_bde_work *wp)
190{
191 struct g_bde_softc *sc;
192 u_char *d;
193 off_t o;
194 u_char skey[G_BDE_SKEYLEN];
195 keyInstance ki;
196 cipherInstance ci;
197
198 sc = wp->softc;
199 d = wp->sp->data;
200 AES_init(&ci);
201 /*
202 * Do not unroll this loop!
203 * Our zone may be significantly wider than the amount of random
204 * bytes arc4rand likes to give in one reseeding, whereas our
205 * sectorsize is far more likely to be in the same range.
206 */
207 for (o = 0; o < wp->length; o += sc->sectorsize) {
208 arc4rand(d, sc->sectorsize, 0);
209 arc4rand(&skey, sizeof skey, 0);
210 AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
211 AES_encrypt(&ci, &ki, d, d, sc->sectorsize);
212 d += sc->sectorsize;
213 }
214 /*
215 * Having written a long random sequence to disk here, we want to
216 * force a reseed, to avoid weakening the next time we use random
217 * data for something important.
218 */
219 arc4rand(&o, sizeof o, 1);
220}
221
222/*
223 * Calculate the total payload size of the encrypted device.
224 *
225 * Security objectives: none.
226 *
227 * This function needs to agree with g_bde_map_sector() about things.
228 */
229
230uint64_t
231g_bde_max_sector(struct g_bde_key *kp)
232{
233 uint64_t maxsect;
234
235 maxsect = kp->media_width;
236 maxsect /= kp->zone_width;
237 maxsect *= kp->zone_cont;
238 return (maxsect);
239}
240
241/*
242 * Convert an unencrypted side offset to offsets on the encrypted side.
243 *
244 * Security objective: Make it harder to identify what sectors contain what
245 * on a "cold" disk image.
246 *
247 * We do this by adding the "keyoffset" from the lock to the physical sector
248 * number modulus the available number of sectors. Since all physical sectors
249 * presumably look the same cold, this will do.
250 *
251 * As part of the mapping we have to skip the lock sectors which we know
252 * the physical address off. We also truncate the work packet, respecting
253 * zone boundaries and lock sectors, so that we end up with a sequence of
254 * sectors which are physically contiguous.
255 *
256 * Shuffling things further is an option, but the incremental frustration is
257 * not currently deemed worth the run-time performance hit resulting from the
258 * increased number of disk arm movements it would incur.
259 *
260 * This function offers nothing but a trivial diversion for an attacker able
261 * to do "the cleaning lady attack" in its current static mapping form.
262 */
263
264void
265g_bde_map_sector(struct g_bde_work *wp)
266{
267
268 u_int zone, zoff, u, len;
269 uint64_t ko;
270 struct g_bde_softc *sc;
271 struct g_bde_key *kp;
272
273 sc = wp->softc;
274 kp = &sc->key;
275
276 /* find which zone and the offset in it */
277 zone = wp->offset / kp->zone_cont;
278 zoff = wp->offset % kp->zone_cont;
279
280 /* Calculate the offset of the key in the key sector */
281 wp->ko = (zoff / kp->sectorsize) * G_BDE_SKEYLEN;
282
283 /* restrict length to that zone */
284 len = kp->zone_cont - zoff;
|