geom_aes.c revision 115507 
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 115507 2003-05-31 19:28:53Z 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#include <sys/systm.h>
45#include <sys/kernel.h>
46#include <sys/conf.h>
47#include <sys/bio.h>
48#include <sys/malloc.h>
49#include <sys/lock.h>
50#include <sys/mutex.h>
51#include <sys/libkern.h>
52#include <sys/endian.h>
53#include <sys/md5.h>
54#include <sys/errno.h>
55#include <geom/geom.h>
56
57#include <crypto/rijndael/rijndael.h>
58
59#include <crypto/rijndael/rijndael.h>
60
61#define AES_CLASS_NAME "AES"
62
63#define MASTER_KEY_LENGTH	(1024/8)
64
65static const u_char *aes_magic = "<<FreeBSD-GEOM-AES>>";
66static const u_char *aes_magic_random = "<<FreeBSD-GEOM-AES-RANDOM>>";
67static const u_char *aes_magic_test = "<<FreeBSD-GEOM-AES-TEST>>";
68
69
70struct g_aes_softc {
71	enum {
72		KEY_ZERO,
73		KEY_RANDOM,
74		KEY_TEST
75	} keying;
76	u_int	sectorsize;
77	off_t	mediasize;
78	cipherInstance ci;
79	u_char master_key[MASTER_KEY_LENGTH];
80};
81
82/*
83 * Generate a sectorkey from the masterkey and the offset position.
84 *
85 * For KEY_ZERO we just return a key of all zeros.
86 *
87 * We feed the sector byte offset, 16 bytes of the master-key and
88 * the sector byte offset once more to MD5.
89 * The sector byte offset is converted to little-endian format first
90 * to support multi-architecture operation.
91 * We use 16 bytes from the master-key starting at the logical sector
92 * number modulus he length of the master-key.  If need be we wrap
93 * around to the start of the master-key.
94 */
95
96static void
97g_aes_makekey(struct g_aes_softc *sc, off_t off, keyInstance *ki, int dir)
98{
99	MD5_CTX cx;
100	u_int64_t u64;
101	u_int u, u1;
102	u_char *p, buf[16];
103
104	if (sc->keying == KEY_ZERO) {
105		rijndael_makeKey(ki, dir, 128, sc->master_key);
106		return;
107	}
108	MD5Init(&cx);
109	u64 = htole64(off);
110	MD5Update(&cx, (u_char *)&u64, sizeof(u64));
111	u = off / sc->sectorsize;
112	u %= sizeof sc->master_key;
113	p = sc->master_key + u;
114	if (u + 16 <= sizeof(sc->master_key)) {
115		MD5Update(&cx, p, 16);
116	} else {
117		u1 = sizeof sc->master_key - u;
118		MD5Update(&cx, p, u1);
119		MD5Update(&cx, sc->master_key, 16 - u1);
120		u1 = 0;				/* destroy evidence */
121	}
122	u = 0;					/* destroy evidence */
123	MD5Update(&cx, (u_char *)&u64, sizeof(u64));
124	u64 = 0;				/* destroy evidence */
125	MD5Final(buf, &cx);
126	bzero(&cx, sizeof cx);			/* destroy evidence */
127	rijndael_makeKey(ki, dir, 128, buf);
128	bzero(buf, sizeof buf);			/* destroy evidence */
129
130}
131
132static void
133g_aes_read_done(struct bio *bp)
134{
135	struct g_geom *gp;
136	struct g_aes_softc *sc;
137	u_char *p, *b, *e, *sb;
138	keyInstance dkey;
139	off_t o;
140
141	gp = bp->bio_from->geom;
142	sc = gp->softc;
143	sb = g_malloc(sc->sectorsize, M_WAITOK);
144	b = bp->bio_data;
145	e = bp->bio_data;
146	e += bp->bio_length;
147	o = bp->bio_offset - sc->sectorsize;
148	for (p = b; p < e; p += sc->sectorsize) {
149		g_aes_makekey(sc, o, &dkey, DIR_DECRYPT);
150		rijndael_blockDecrypt(&sc->ci, &dkey, p, sc->sectorsize * 8, sb);
151		bcopy(sb, p, sc->sectorsize);
152		o += sc->sectorsize;
153	}
154	bzero(&dkey, sizeof dkey);		/* destroy evidence */
155	bzero(sb, sc->sectorsize);		/* destroy evidence */
156	g_free(sb);
157	g_std_done(bp);
158}
159
160static void
161g_aes_write_done(struct bio *bp)
162{
163
164	bzero(bp->bio_data, bp->bio_length);	/* destroy evidence */
165	g_free(bp->bio_data);
166	g_std_done(bp);
167}
168
169static void
170g_aes_start(struct bio *bp)
171{
172	struct g_geom *gp;
173	struct g_consumer *cp;
174	struct g_aes_softc *sc;
175	struct bio *bp2;
176	u_char *p1, *p2, *b, *e;
177	keyInstance ekey;
178	off_t o;
179
180	gp = bp->bio_to->geom;
181	cp = LIST_FIRST(&gp->consumer);
182	sc = gp->softc;
183	switch (bp->bio_cmd) {
184	case BIO_READ:
185		bp2 = g_clone_bio(bp);
186		if (bp2 == NULL) {
187			g_io_deliver(bp, ENOMEM);
188			return;
189		}
190		bp2->bio_done = g_aes_read_done;
191		bp2->bio_offset += sc->sectorsize;
192		g_io_request(bp2, cp);
193		break;
194	case BIO_WRITE:
195		bp2 = g_clone_bio(bp);
196		if (bp2 == NULL) {
197			g_io_deliver(bp, ENOMEM);
198			return;
199		}
200		bp2->bio_done = g_aes_write_done;
201		bp2->bio_offset += sc->sectorsize;
202		bp2->bio_data = g_malloc(bp->bio_length, M_WAITOK);
203		b = bp->bio_data;
204		e = bp->bio_data;
205		e += bp->bio_length;
206		p2 = bp2->bio_data;
207		o = bp->bio_offset;
208		for (p1 = b; p1 < e; p1 += sc->sectorsize) {
209			g_aes_makekey(sc, o, &ekey, DIR_ENCRYPT);
210			rijndael_blockEncrypt(&sc->ci, &ekey,
211			    p1, sc->sectorsize * 8, p2);
212			p2 += sc->sectorsize;
213			o += sc->sectorsize;
214		}
215		bzero(&ekey, sizeof ekey);	/* destroy evidence */
216		g_io_request(bp2, cp);
217		break;
218	case BIO_GETATTR:
219		bp2 = g_clone_bio(bp);
220		if (bp2 == NULL) {
221			g_io_deliver(bp, ENOMEM);
222			return;
223		}
224		bp2->bio_done = g_std_done;
225		bp2->bio_offset += sc->sectorsize;
226		g_io_request(bp2, cp);
227		break;
228	default:
229		g_io_deliver(bp, EOPNOTSUPP);
230		return;
231	}
232	return;
233}
234
235static void
236g_aes_orphan(struct g_consumer *cp)
237{
238	struct g_geom *gp;
239	struct g_aes_softc *sc;
240
241	g_trace(G_T_TOPOLOGY, "g_aes_orphan(%p/%s)", cp, cp->provider->name);
242	g_topology_assert();
243	KASSERT(cp->provider->error != 0,
244		("g_aes_orphan with error == 0"));
245
246	gp = cp->geom;
247	sc = gp->softc;
248	g_wither_geom(gp, cp->provider->error);
249	bzero(sc, sizeof(struct g_aes_softc));	/* destroy evidence */
250	g_free(sc);
251	return;
252}
253
254static int
255g_aes_access(struct g_provider *pp, int dr, int dw, int de)
256{
257	struct g_geom *gp;
258	struct g_consumer *cp;
259
260	gp = pp->geom;
261	cp = LIST_FIRST(&gp->consumer);
262	/* On first open, grab an extra "exclusive" bit */
263	if (cp->acr == 0 && cp->acw == 0 && cp->ace == 0)
264		de++;
265	/* ... and let go of it on last close */
266	if ((cp->acr + dr) == 0 && (cp->acw + dw) == 0 && (cp->ace + de) == 1)
267		de--;
268	return (g_access_rel(cp, dr, dw, de));
269}
270
271static struct g_geom *
272g_aes_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
273{
274	struct g_geom *gp;
275	struct g_consumer *cp;
276	struct g_aes_softc *sc;
277	int error;
278	u_int sectorsize;
279	off_t mediasize;
280	u_char *buf;
281
282	g_trace(G_T_TOPOLOGY, "aes_taste(%s,%s)", mp->name, pp->name);
283	g_topology_assert();
284	gp = g_new_geomf(mp, "%s.aes", pp->name);
285	gp->start = g_aes_start;
286	gp->orphan = g_aes_orphan;
287	gp->spoiled = g_std_spoiled;
288	cp = g_new_consumer(gp);
289	g_attach(cp, pp);
290	error = g_access_rel(cp, 1, 0, 0);
291	if (error) {
292		g_detach(cp);
293		g_destroy_consumer(cp);
294		g_destroy_geom(gp);
295		return (NULL);
296	}
297	buf = NULL;
298	g_topology_unlock();
299	do {
300		if (gp->rank != 2)
301			break;
302		sectorsize = cp->provider->sectorsize;
303		mediasize = cp->provider->mediasize;
304		buf = g_read_data(cp, 0, sectorsize, &error);
305		if (buf == NULL || error != 0) {
306			break;
307		}
308		sc = g_malloc(sizeof(struct g_aes_softc), M_WAITOK | M_ZERO);
309		if (!memcmp(buf, aes_magic, strlen(aes_magic))) {
310			sc->keying = KEY_ZERO;
311		} else if (!memcmp(buf, aes_magic_random,
312		    strlen(aes_magic_random))) {
313			sc->keying = KEY_RANDOM;
314		} else if (!memcmp(buf, aes_magic_test,
315		    strlen(aes_magic_test))) {
316			sc->keying = KEY_TEST;
317		} else {
318			g_free(sc);
319			break;
320		}
321		g_free(buf);
322		gp->softc = sc;
323		gp->access = g_aes_access;
324		sc->sectorsize = sectorsize;
325		sc->mediasize = mediasize - sectorsize;
326		rijndael_cipherInit(&sc->ci, MODE_CBC, NULL);
327		if (sc->keying == KEY_TEST) {
328			int i;
329			u_char *p;
330
331			p = sc->master_key;
332			for (i = 0; i < (int)sizeof sc->master_key; i ++)
333				*p++ = i;
334		}
335		if (sc->keying == KEY_RANDOM) {
336			int i;
337			u_int32_t u;
338			u_char *p;
339
340			p = sc->master_key;
341			for (i = 0; i < (int)sizeof sc->master_key; i += sizeof u) {
342				u = arc4random();
343				*p++ = u;
344				*p++ = u >> 8;
345				*p++ = u >> 16;
346				*p++ = u >> 24;
347			}
348		}
349		g_topology_lock();
350		pp = g_new_providerf(gp, gp->name);
351		pp->mediasize = mediasize - sectorsize;
352		pp->sectorsize = sectorsize;
353		g_error_provider(pp, 0);
354		g_topology_unlock();
355	} while(0);
356	g_topology_lock();
357	if (buf)
358		g_free(buf);
359	g_access_rel(cp, -1, 0, 0);
360	if (gp->softc != NULL)
361		return (gp);
362	g_detach(cp);
363	g_destroy_consumer(cp);
364	g_destroy_geom(gp);
365	return (NULL);
366}
367
368static struct g_class g_aes_class	= {
369	.name = AES_CLASS_NAME,
370	.taste = g_aes_taste,
371};
372
373DECLARE_GEOM_CLASS(g_aes_class, g_aes);
374