361 lines
10 KiB
C
361 lines
10 KiB
C
/*-
|
|
* Copyright (c) 2002 Poul-Henning Kamp
|
|
* Copyright (c) 2002 Networks Associates Technology, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
|
|
* and NAI Labs, the Security Research Division of Network Associates, Inc.
|
|
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
|
|
* DARPA CHATS research program.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
/* This source file contains the functions responsible for the crypto, keying
|
|
* and mapping operations on the I/O requests.
|
|
*
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/bio.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/queue.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/libkern.h>
|
|
#include <sys/endian.h>
|
|
#include <sys/md5.h>
|
|
|
|
#include <crypto/rijndael/rijndael.h>
|
|
#include <crypto/sha2/sha2.h>
|
|
|
|
#include <geom/geom.h>
|
|
#include <geom/bde/g_bde.h>
|
|
|
|
/*
|
|
* XXX: Debugging DO NOT ENABLE
|
|
*/
|
|
#undef MD5_KEY
|
|
|
|
/*
|
|
* Derive kkey from mkey + sector offset.
|
|
*
|
|
* Security objective: Derive a potentially very large number of distinct skeys
|
|
* from the comparatively small key material in our mkey, in such a way that
|
|
* if one, more or even many of the kkeys are compromised, this does not
|
|
* significantly help an attack on other kkeys and in particular does not
|
|
* weaken or compromised the mkey.
|
|
*
|
|
* First we MD5 hash the sectornumber with the salt from the lock sector.
|
|
* The salt prevents the precalculation and statistical analysis of the MD5
|
|
* output which would be possible if we only gave it the sectornumber.
|
|
*
|
|
* The MD5 hash is used to pick out 16 bytes from the masterkey, which
|
|
* are then hashed with MD5 together with the sector number.
|
|
*
|
|
* The resulting MD5 hash is the kkey.
|
|
*/
|
|
|
|
static void
|
|
g_bde_kkey(struct g_bde_softc *sc, keyInstance *ki, int dir, off_t sector)
|
|
{
|
|
u_int t;
|
|
MD5_CTX ct;
|
|
u_char buf[16];
|
|
u_char buf2[8];
|
|
|
|
/* We have to be architecture neutral */
|
|
le64enc(buf2, sector);
|
|
|
|
MD5Init(&ct);
|
|
MD5Update(&ct, sc->key.salt, 8);
|
|
MD5Update(&ct, buf2, sizeof buf2);
|
|
MD5Update(&ct, sc->key.salt + 8, 8);
|
|
MD5Final(buf, &ct);
|
|
|
|
MD5Init(&ct);
|
|
for (t = 0; t < 16; t++) {
|
|
MD5Update(&ct, &sc->key.mkey[buf[t]], 1);
|
|
if (t == 8)
|
|
MD5Update(&ct, buf2, sizeof buf2);
|
|
}
|
|
bzero(buf2, sizeof buf2);
|
|
MD5Final(buf, &ct);
|
|
bzero(&ct, sizeof ct);
|
|
AES_makekey(ki, dir, G_BDE_KKEYBITS, buf);
|
|
bzero(buf, sizeof buf);
|
|
}
|
|
|
|
/*
|
|
* Encryption work for read operation.
|
|
*
|
|
* Security objective: Find the kkey, find the skey, decrypt the sector data.
|
|
*/
|
|
|
|
void
|
|
g_bde_crypt_read(struct g_bde_work *wp)
|
|
{
|
|
struct g_bde_softc *sc;
|
|
u_char *d;
|
|
u_int n;
|
|
off_t o;
|
|
u_char skey[G_BDE_SKEYLEN];
|
|
keyInstance ki;
|
|
cipherInstance ci;
|
|
|
|
|
|
AES_init(&ci);
|
|
sc = wp->softc;
|
|
o = 0;
|
|
for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
|
|
d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
|
|
g_bde_kkey(sc, &ki, DIR_DECRYPT, wp->offset + o);
|
|
AES_decrypt(&ci, &ki, d, skey, sizeof skey);
|
|
d = (u_char *)wp->data + o;
|
|
AES_makekey(&ki, DIR_DECRYPT, G_BDE_SKEYBITS, skey);
|
|
AES_decrypt(&ci, &ki, d, d, sc->sectorsize);
|
|
}
|
|
bzero(skey, sizeof skey);
|
|
bzero(&ci, sizeof ci);
|
|
bzero(&ki, sizeof ki);
|
|
}
|
|
|
|
/*
|
|
* Encryption work for write operation.
|
|
*
|
|
* Security objective: Create random skey, encrypt sector data,
|
|
* encrypt skey with the kkey.
|
|
*/
|
|
|
|
void
|
|
g_bde_crypt_write(struct g_bde_work *wp)
|
|
{
|
|
u_char *s, *d;
|
|
struct g_bde_softc *sc;
|
|
u_int n;
|
|
off_t o;
|
|
u_char skey[G_BDE_SKEYLEN];
|
|
keyInstance ki;
|
|
cipherInstance ci;
|
|
|
|
sc = wp->softc;
|
|
AES_init(&ci);
|
|
o = 0;
|
|
for (n = 0; o < wp->length; n++, o += sc->sectorsize) {
|
|
|
|
s = (u_char *)wp->data + o;
|
|
d = (u_char *)wp->sp->data + o;
|
|
arc4rand(skey, sizeof skey, 0);
|
|
AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
|
|
AES_encrypt(&ci, &ki, s, d, sc->sectorsize);
|
|
|
|
d = (u_char *)wp->ksp->data + wp->ko + n * G_BDE_SKEYLEN;
|
|
g_bde_kkey(sc, &ki, DIR_ENCRYPT, wp->offset + o);
|
|
AES_encrypt(&ci, &ki, skey, d, sizeof skey);
|
|
bzero(skey, sizeof skey);
|
|
}
|
|
bzero(skey, sizeof skey);
|
|
bzero(&ci, sizeof ci);
|
|
bzero(&ki, sizeof ki);
|
|
}
|
|
|
|
/*
|
|
* Encryption work for delete operation.
|
|
*
|
|
* Security objective: Write random data to the sectors.
|
|
*
|
|
* XXX: At a hit in performance we would trash the encrypted skey as well.
|
|
* XXX: This would add frustration to the cleaning lady attack by making
|
|
* XXX: deletes look like writes.
|
|
*/
|
|
|
|
void
|
|
g_bde_crypt_delete(struct g_bde_work *wp)
|
|
{
|
|
struct g_bde_softc *sc;
|
|
u_char *d;
|
|
off_t o;
|
|
u_char skey[G_BDE_SKEYLEN];
|
|
keyInstance ki;
|
|
cipherInstance ci;
|
|
|
|
sc = wp->softc;
|
|
d = wp->sp->data;
|
|
AES_init(&ci);
|
|
/*
|
|
* Do not unroll this loop!
|
|
* Our zone may be significantly wider than the amount of random
|
|
* bytes arc4rand likes to give in one reseeding, whereas our
|
|
* sectorsize is far more likely to be in the same range.
|
|
*/
|
|
for (o = 0; o < wp->length; o += sc->sectorsize) {
|
|
arc4rand(d, sc->sectorsize, 0);
|
|
arc4rand(skey, sizeof skey, 0);
|
|
AES_makekey(&ki, DIR_ENCRYPT, G_BDE_SKEYBITS, skey);
|
|
AES_encrypt(&ci, &ki, d, d, sc->sectorsize);
|
|
d += sc->sectorsize;
|
|
}
|
|
/*
|
|
* Having written a long random sequence to disk here, we want to
|
|
* force a reseed, to avoid weakening the next time we use random
|
|
* data for something important.
|
|
*/
|
|
arc4rand(&o, sizeof o, 1);
|
|
}
|
|
|
|
/*
|
|
* Calculate the total payload size of the encrypted device.
|
|
*
|
|
* Security objectives: none.
|
|
*
|
|
* This function needs to agree with g_bde_map_sector() about things.
|
|
*/
|
|
|
|
uint64_t
|
|
g_bde_max_sector(struct g_bde_key *kp)
|
|
{
|
|
uint64_t maxsect;
|
|
|
|
maxsect = kp->media_width;
|
|
maxsect /= kp->zone_width;
|
|
maxsect *= kp->zone_cont;
|
|
return (maxsect);
|
|
}
|
|
|
|
/*
|
|
* Convert an unencrypted side offset to offsets on the encrypted side.
|
|
*
|
|
* Security objective: Make it harder to identify what sectors contain what
|
|
* on a "cold" disk image.
|
|
*
|
|
* We do this by adding the "keyoffset" from the lock to the physical sector
|
|
* number modulus the available number of sectors. Since all physical sectors
|
|
* presumably look the same cold, this will do.
|
|
*
|
|
* As part of the mapping we have to skip the lock sectors which we know
|
|
* the physical address off. We also truncate the work packet, respecting
|
|
* zone boundaries and lock sectors, so that we end up with a sequence of
|
|
* sectors which are physically contiguous.
|
|
*
|
|
* Shuffling things further is an option, but the incremental frustration is
|
|
* not currently deemed worth the run-time performance hit resulting from the
|
|
* increased number of disk arm movements it would incur.
|
|
*
|
|
* This function offers nothing but a trivial diversion for an attacker able
|
|
* to do "the cleaning lady attack" in its current static mapping form.
|
|
*/
|
|
|
|
void
|
|
g_bde_map_sector(struct g_bde_work *wp)
|
|
{
|
|
|
|
u_int zone, zoff, u, len;
|
|
uint64_t ko;
|
|
struct g_bde_softc *sc;
|
|
struct g_bde_key *kp;
|
|
|
|
sc = wp->softc;
|
|
kp = &sc->key;
|
|
|
|
/* find which zone and the offset in it */
|
|
zone = wp->offset / kp->zone_cont;
|
|
zoff = wp->offset % kp->zone_cont;
|
|
|
|
/* Calculate the offset of the key in the key sector */
|
|
wp->ko = (zoff / kp->sectorsize) * G_BDE_SKEYLEN;
|
|
|
|
/* restrict length to that zone */
|
|
len = kp->zone_cont - zoff;
|
|
|
|
/* ... and in general */
|
|
if (len > DFLTPHYS)
|
|
len = DFLTPHYS;
|
|
|
|
if (len < wp->length)
|
|
wp->length = len;
|
|
|
|
/* Find physical sector address */
|
|
wp->so = zone * kp->zone_width + zoff;
|
|
wp->so += kp->keyoffset;
|
|
wp->so %= kp->media_width;
|
|
if (wp->so + wp->length > kp->media_width)
|
|
wp->length = kp->media_width - wp->so;
|
|
wp->so += kp->sector0;
|
|
|
|
/* The key sector is the last in this zone. */
|
|
wp->kso = zone * kp->zone_width + kp->zone_cont;
|
|
wp->kso += kp->keyoffset;
|
|
wp->kso %= kp->media_width;
|
|
wp->kso += kp->sector0;
|
|
|
|
/* Compensate for lock sectors */
|
|
for (u = 0; u < G_BDE_MAXKEYS; u++) {
|
|
/* Find the start of this lock sector */
|
|
ko = kp->lsector[u] & ~((uint64_t)kp->sectorsize - 1);
|
|
|
|
if (wp->kso >= ko)
|
|
wp->kso += kp->sectorsize;
|
|
|
|
if (wp->so >= ko) {
|
|
/* lock sector before work packet */
|
|
wp->so += kp->sectorsize;
|
|
} else if ((wp->so + wp->length) > ko) {
|
|
/* lock sector in work packet, truncate */
|
|
wp->length = ko - wp->so;
|
|
}
|
|
}
|
|
|
|
#if 0
|
|
printf("off %jd len %jd so %jd ko %jd kso %u\n",
|
|
(intmax_t)wp->offset,
|
|
(intmax_t)wp->length,
|
|
(intmax_t)wp->so,
|
|
(intmax_t)wp->kso,
|
|
wp->ko);
|
|
#endif
|
|
KASSERT(wp->so + wp->length <= kp->sectorN,
|
|
("wp->so (%jd) + wp->length (%jd) > EOM (%jd), offset = %jd",
|
|
(intmax_t)wp->so,
|
|
(intmax_t)wp->length,
|
|
(intmax_t)kp->sectorN,
|
|
(intmax_t)wp->offset));
|
|
|
|
KASSERT(wp->kso + kp->sectorsize <= kp->sectorN,
|
|
("wp->kso (%jd) + kp->sectorsize > EOM (%jd), offset = %jd",
|
|
(intmax_t)wp->kso,
|
|
(intmax_t)kp->sectorN,
|
|
(intmax_t)wp->offset));
|
|
|
|
KASSERT(wp->so >= kp->sector0,
|
|
("wp->so (%jd) < BOM (%jd), offset = %jd",
|
|
(intmax_t)wp->so,
|
|
(intmax_t)kp->sector0,
|
|
(intmax_t)wp->offset));
|
|
|
|
KASSERT(wp->kso >= kp->sector0,
|
|
("wp->kso (%jd) <BOM (%jd), offset = %jd",
|
|
(intmax_t)wp->kso,
|
|
(intmax_t)kp->sector0,
|
|
(intmax_t)wp->offset));
|
|
}
|