geom_aes.c revision 112552 
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 * 3. The names of the authors may not be used to endorse or promote
20 *    products derived from this software without specific prior written
21 *    permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * $FreeBSD: head/sys/geom/geom_aes.c 112552 2003-03-24 19:30:15Z phk $
36 *
37 * This method provides AES encryption with a compiled in key (default
38 * all zeroes).
39 *
40 * XXX: This could probably save a lot of code by pretending to be a slicer.
41 */
42
43#include <sys/param.h>
44#ifndef _KERNEL
45#include <stdio.h>
46#include <string.h>
47#include <stdlib.h>
48#include <signal.h>
49#include <err.h>
50#else
51#include <sys/systm.h>
52#include <sys/kernel.h>
53#include <sys/conf.h>
54#include <sys/bio.h>
55#include <sys/malloc.h>
56#include <sys/lock.h>
57#include <sys/mutex.h>
58#include <sys/libkern.h>
59#endif
60#include <sys/endian.h>
61#include <sys/md5.h>
62#include <sys/errno.h>
63#include <geom/geom.h>
64
65#include <crypto/rijndael/rijndael.h>
66
67#include <crypto/rijndael/rijndael.h>
68
69#define AES_CLASS_NAME "AES"
70
71#define MASTER_KEY_LENGTH	(1024/8)
72
73static const u_char *aes_magic = "<<FreeBSD-GEOM-AES>>";
74static const u_char *aes_magic_random = "<<FreeBSD-GEOM-AES-RANDOM>>";
75static const u_char *aes_magic_test = "<<FreeBSD-GEOM-AES-TEST>>";
76
77
78struct g_aes_softc {
79	enum {
80		KEY_ZERO,
81		KEY_RANDOM,
82		KEY_TEST
83	} keying;
84	u_int	sectorsize;
85	off_t	mediasize;
86	cipherInstance ci;
87	u_char master_key[MASTER_KEY_LENGTH];
88};
89
90/*
91 * Generate a sectorkey from the masterkey and the offset position.
92 *
93 * For KEY_ZERO we just return a key of all zeros.
94 *
95 * We feed the sector byte offset, 16 bytes of the master-key and
96 * the sector byte offset once more to MD5.
97 * The sector byte offset is converted to little-endian format first
98 * to support multi-architecture operation.
99 * We use 16 bytes from the master-key starting at the logical sector
100 * number modulus he length of the master-key.  If need be we wrap
101 * around to the start of the master-key.
102 */
103
104static void
105g_aes_makekey(struct g_aes_softc *sc, off_t off, keyInstance *ki, int dir)
106{
107	MD5_CTX cx;
108	u_int64_t u64;
109	u_int u, u1;
110	u_char *p, buf[16];
111
112	if (sc->keying == KEY_ZERO) {
113		rijndael_makeKey(ki, dir, 128, sc->master_key);
114		return;
115	}
116	MD5Init(&cx);
117	u64 = htole64(off);
118	MD5Update(&cx, (u_char *)&u64, sizeof(u64));
119	u = off / sc->sectorsize;
120	u %= sizeof sc->master_key;
121	p = sc->master_key + u;
122	if (u + 16 <= sizeof(sc->master_key)) {
123		MD5Update(&cx, p, 16);
124	} else {
125		u1 = sizeof sc->master_key - u;
126		MD5Update(&cx, p, u1);
127		MD5Update(&cx, sc->master_key, 16 - u1);
128		u1 = 0;				/* destroy evidence */
129	}
130	u = 0;					/* destroy evidence */
131	MD5Update(&cx, (u_char *)&u64, sizeof(u64));
132	u64 = 0;				/* destroy evidence */
133	MD5Final(buf, &cx);
134	bzero(&cx, sizeof cx);			/* destroy evidence */
135	rijndael_makeKey(ki, dir, 128, buf);
136	bzero(buf, sizeof buf);			/* destroy evidence */
137
138}
139
140static void
141g_aes_read_done(struct bio *bp)
142{
143	struct g_geom *gp;
144	struct g_aes_softc *sc;
145	u_char *p, *b, *e, *sb;
146	keyInstance dkey;
147	off_t o;
148
149	gp = bp->bio_from->geom;
150	sc = gp->softc;
151	sb = g_malloc(sc->sectorsize, M_WAITOK);
152	b = bp->bio_data;
153	e = bp->bio_data;
154	e += bp->bio_length;
155	o = bp->bio_offset - sc->sectorsize;
156	for (p = b; p < e; p += sc->sectorsize) {
157		g_aes_makekey(sc, o, &dkey, DIR_DECRYPT);
158		rijndael_blockDecrypt(&sc->ci, &dkey, p, sc->sectorsize * 8, sb);
159		bcopy(sb, p, sc->sectorsize);
160		o += sc->sectorsize;
161	}
162	bzero(&dkey, sizeof dkey);		/* destroy evidence */
163	bzero(sb, sc->sectorsize);		/* destroy evidence */
164	g_free(sb);
165	g_std_done(bp);
166}
167
168static void
169g_aes_write_done(struct bio *bp)
170{
171	struct g_aes_softc *sc;
172	struct g_geom *gp;
173
174	gp = bp->bio_to->geom;
175	sc = gp->softc;
176	bzero(bp->bio_data, bp->bio_length);	/* destroy evidence */
177	g_free(bp->bio_data);
178	g_std_done(bp);
179}
180
181static void
182g_aes_start(struct bio *bp)
183{
184	struct g_geom *gp;
185	struct g_consumer *cp;
186	struct g_aes_softc *sc;
187	struct bio *bp2;
188	u_char *p1, *p2, *b, *e;
189	keyInstance ekey;
190	off_t o;
191
192	gp = bp->bio_to->geom;
193	cp = LIST_FIRST(&gp->consumer);
194	sc = gp->softc;
195	switch (bp->bio_cmd) {
196	case BIO_READ:
197		bp2 = g_clone_bio(bp);
198		if (bp2 == NULL) {
199			g_io_deliver(bp, ENOMEM);
200			return;
201		}
202		bp2->bio_done = g_aes_read_done;
203		bp2->bio_offset += sc->sectorsize;
204		g_io_request(bp2, cp);
205		break;
206	case BIO_WRITE:
207		bp2 = g_clone_bio(bp);
208		if (bp2 == NULL) {
209			g_io_deliver(bp, ENOMEM);
210			return;
211		}
212		bp2->bio_done = g_aes_write_done;
213		bp2->bio_offset += sc->sectorsize;
214		bp2->bio_data = g_malloc(bp->bio_length, M_WAITOK);
215		b = bp->bio_data;
216		e = bp->bio_data;
217		e += bp->bio_length;
218		p2 = bp2->bio_data;
219		o = bp->bio_offset;
220		for (p1 = b; p1 < e; p1 += sc->sectorsize) {
221			g_aes_makekey(sc, o, &ekey, DIR_ENCRYPT);
222			rijndael_blockEncrypt(&sc->ci, &ekey,
223			    p1, sc->sectorsize * 8, p2);
224			p2 += sc->sectorsize;
225			o += sc->sectorsize;
226		}
227		bzero(&ekey, sizeof ekey);	/* destroy evidence */
228		g_io_request(bp2, cp);
229		break;
230	case BIO_GETATTR:
231	case BIO_SETATTR:
232		bp2 = g_clone_bio(bp);
233		if (bp2 == NULL) {
234			g_io_deliver(bp, ENOMEM);
235			return;
236		}
237		bp2->bio_done = g_std_done;
238		bp2->bio_offset += sc->sectorsize;
239		g_io_request(bp2, cp);
240		break;
241	default:
242		g_io_deliver(bp, EOPNOTSUPP);
243		return;
244	}
245	return;
246}
247
248static void
249g_aes_orphan(struct g_consumer *cp)
250{
251	struct g_geom *gp;
252	struct g_provider *pp;
253	struct g_aes_softc *sc;
254	int error;
255
256	g_trace(G_T_TOPOLOGY, "g_aes_orphan(%p/%s)", cp, cp->provider->name);
257	g_topology_assert();
258	KASSERT(cp->provider->error != 0,
259		("g_aes_orphan with error == 0"));
260
261	gp = cp->geom;
262	sc = gp->softc;
263	gp->flags |= G_GEOM_WITHER;
264	error = cp->provider->error;
265	LIST_FOREACH(pp, &gp->provider, provider)
266		g_orphan_provider(pp, error);
267	bzero(sc, sizeof(struct g_aes_softc));	/* destroy evidence */
268	return;
269}
270
271static int
272g_aes_access(struct g_provider *pp, int dr, int dw, int de)
273{
274	struct g_geom *gp;
275	struct g_consumer *cp;
276
277	gp = pp->geom;
278	cp = LIST_FIRST(&gp->consumer);
279	/* On first open, grab an extra "exclusive" bit */
280	if (cp->acr == 0 && cp->acw == 0 && cp->ace == 0)
281		de++;
282	/* ... and let go of it on last close */
283	if ((cp->acr + dr) == 0 && (cp->acw + dw) == 0 && (cp->ace + de) == 1)
284		de--;
285	return (g_access_rel(cp, dr, dw, de));
286}
287
288static struct g_geom *
289g_aes_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
290{
291	struct g_geom *gp;
292	struct g_consumer *cp;
293	struct g_aes_softc *sc;
294	int error;
295	u_int sectorsize;
296	off_t mediasize;
297	u_char *buf;
298
299	g_trace(G_T_TOPOLOGY, "aes_taste(%s,%s)", mp->name, pp->name);
300	g_topology_assert();
301	gp = g_new_geomf(mp, "%s.aes", pp->name);
302	gp->start = g_aes_start;
303	gp->orphan = g_aes_orphan;
304	gp->spoiled = g_std_spoiled;
305	cp = g_new_consumer(gp);
306	g_attach(cp, pp);
307	error = g_access_rel(cp, 1, 0, 0);
308	if (error) {
309		g_detach(cp);
310		g_destroy_consumer(cp);
311		g_destroy_geom(gp);
312		return (NULL);
313	}
314	buf = NULL;
315	g_topology_unlock();
316	while (1) {
317		if (gp->rank != 2)
318			break;
319		sectorsize = cp->provider->sectorsize;
320		mediasize = cp->provider->mediasize;
321		buf = g_read_data(cp, 0, sectorsize, &error);
322		if (buf == NULL || error != 0) {
323			break;
324		}
325		sc = g_malloc(sizeof(struct g_aes_softc), M_WAITOK | M_ZERO);
326		if (!memcmp(buf, aes_magic, strlen(aes_magic))) {
327			sc->keying = KEY_ZERO;
328		} else if (!memcmp(buf, aes_magic_random,
329		    strlen(aes_magic_random))) {
330			sc->keying = KEY_RANDOM;
331		} else if (!memcmp(buf, aes_magic_test,
332		    strlen(aes_magic_test))) {
333			sc->keying = KEY_TEST;
334		} else {
335			g_free(sc);
336			break;
337		}
338		gp->softc = sc;
339		gp->access = g_aes_access;
340		sc->sectorsize = sectorsize;
341		sc->mediasize = mediasize - sectorsize;
342		rijndael_cipherInit(&sc->ci, MODE_CBC, NULL);
343		if (sc->keying == KEY_TEST) {
344			int i;
345			u_char *p;
346
347			p = sc->master_key;
348			for (i = 0; i < (int)sizeof sc->master_key; i ++)
349				*p++ = i;
350		}
351		if (sc->keying == KEY_RANDOM) {
352			int i;
353			u_int32_t u;
354			u_char *p;
355
356			p = sc->master_key;
357			for (i = 0; i < (int)sizeof sc->master_key; i += sizeof u) {
358				u = arc4random();
359				*p++ = u;
360				*p++ = u >> 8;
361				*p++ = u >> 16;
362				*p++ = u >> 24;
363			}
364		}
365		g_topology_lock();
366		pp = g_new_providerf(gp, gp->name);
367		pp->mediasize = mediasize - sectorsize;
368		pp->sectorsize = sectorsize;
369		g_error_provider(pp, 0);
370		g_topology_unlock();
371		break;
372	}
373	g_topology_lock();
374	if (buf)
375		g_free(buf);
376	g_access_rel(cp, -1, 0, 0);
377	if (gp->softc != NULL)
378		return (gp);
379	g_detach(cp);
380	g_destroy_consumer(cp);
381	g_destroy_geom(gp);
382	return (NULL);
383}
384
385static struct g_class g_aes_class	= {
386	.name = AES_CLASS_NAME,
387	.taste = g_aes_taste,
388	G_CLASS_INITIALIZER
389};
390
391DECLARE_GEOM_CLASS(g_aes_class, g_aes);
392