1/* XTS: as defined in IEEE1619/D16
  2 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
  3 *	(sector sizes which are not a multiple of 16 bytes are,
  4 *	however currently unsupported)
  5 *
  6 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
  7 *
  8 * Based om ecb.c
  9 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 10 *
 11 * This program is free software; you can redistribute it and/or modify it
 12 * under the terms of the GNU General Public License as published by the Free
 13 * Software Foundation; either version 2 of the License, or (at your option)
 14 * any later version.
 15 */
 16#include <crypto/algapi.h>
 17#include <linux/err.h>
 18#include <linux/init.h>
 19#include <linux/kernel.h>
 20#include <linux/module.h>
 21#include <linux/scatterlist.h>
 22#include <linux/slab.h>
 23
 24#include <crypto/xts.h>
 25#include <crypto/b128ops.h>
 26#include <crypto/gf128mul.h>
 27
 28struct priv {
 29	struct crypto_cipher *child;
 30	struct crypto_cipher *tweak;
 31};
 32
 33static int setkey(struct crypto_tfm *parent, const u8 *key,
 34		  unsigned int keylen)
 35{
 36	struct priv *ctx = crypto_tfm_ctx(parent);
 37	struct crypto_cipher *child = ctx->tweak;
 38	u32 *flags = &parent->crt_flags;
 39	int err;
 40
 41	/* key consists of keys of equal size concatenated, therefore
 42	 * the length must be even */
 43	if (keylen % 2) {
 44		/* tell the user why there was an error */
 45		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 46		return -EINVAL;
 47	}
 48
 49	/* we need two cipher instances: one to compute the initial 'tweak'
 50	 * by encrypting the IV (usually the 'plain' iv) and the other
 51	 * one to encrypt and decrypt the data */
 52
 53	/* tweak cipher, uses Key2 i.e. the second half of *key */
 54	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 55	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 56				       CRYPTO_TFM_REQ_MASK);
 57	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
 58	if (err)
 59		return err;
 60
 61	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 62				     CRYPTO_TFM_RES_MASK);
 63
 64	child = ctx->child;
 65
 66	/* data cipher, uses Key1 i.e. the first half of *key */
 67	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 68	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 69				       CRYPTO_TFM_REQ_MASK);
 70	err = crypto_cipher_setkey(child, key, keylen/2);
 71	if (err)
 72		return err;
 73
 74	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 75				     CRYPTO_TFM_RES_MASK);
 76
 77	return 0;
 78}
 79
 80struct sinfo {
 81	be128 *t;
 82	struct crypto_tfm *tfm;
 83	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 84};
 85
 86static inline void xts_round(struct sinfo *s, void *dst, const void *src)
 87{
 88	be128_xor(dst, s->t, src);		/* PP <- T xor P */
 89	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */
 90	be128_xor(dst, dst, s->t);		/* C <- T xor CC */
 91}
 92
 93static int crypt(struct blkcipher_desc *d,
 94		 struct blkcipher_walk *w, struct priv *ctx,
 95		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
 96		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
 97{
 98	int err;
 99	unsigned int avail;
100	const int bs = XTS_BLOCK_SIZE;
101	struct sinfo s = {
102		.tfm = crypto_cipher_tfm(ctx->child),
103		.fn = fn
104	};
105	u8 *wsrc;
106	u8 *wdst;
107
108	err = blkcipher_walk_virt(d, w);
109	if (!w->nbytes)
110		return err;
111
112	s.t = (be128 *)w->iv;
113	avail = w->nbytes;
114
115	wsrc = w->src.virt.addr;
116	wdst = w->dst.virt.addr;
117
118	/* calculate first value of T */
119	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
120
121	goto first;
122
123	for (;;) {
124		do {
125			gf128mul_x_ble(s.t, s.t);
126
127first:
128			xts_round(&s, wdst, wsrc);
129
130			wsrc += bs;
131			wdst += bs;
132		} while ((avail -= bs) >= bs);
133
134		err = blkcipher_walk_done(d, w, avail);
135		if (!w->nbytes)
136			break;
137
138		avail = w->nbytes;
139
140		wsrc = w->src.virt.addr;
141		wdst = w->dst.virt.addr;
142	}
143
144	return err;
145}
146
147static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
148		   struct scatterlist *src, unsigned int nbytes)
149{
150	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
151	struct blkcipher_walk w;
152
153	blkcipher_walk_init(&w, dst, src, nbytes);
154	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
155		     crypto_cipher_alg(ctx->child)->cia_encrypt);
156}
157
158static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
159		   struct scatterlist *src, unsigned int nbytes)
160{
161	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
162	struct blkcipher_walk w;
163
164	blkcipher_walk_init(&w, dst, src, nbytes);
165	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
166		     crypto_cipher_alg(ctx->child)->cia_decrypt);
167}
168
169int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
170	      struct scatterlist *ssrc, unsigned int nbytes,
171	      struct xts_crypt_req *req)
172{
173	const unsigned int bsize = XTS_BLOCK_SIZE;
174	const unsigned int max_blks = req->tbuflen / bsize;
175	struct blkcipher_walk walk;
176	unsigned int nblocks;
177	be128 *src, *dst, *t;
178	be128 *t_buf = req->tbuf;
179	int err, i;
180
181	BUG_ON(max_blks < 1);
182
183	blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
184
185	err = blkcipher_walk_virt(desc, &walk);
186	nbytes = walk.nbytes;
187	if (!nbytes)
188		return err;
189
190	nblocks = min(nbytes / bsize, max_blks);
191	src = (be128 *)walk.src.virt.addr;
192	dst = (be128 *)walk.dst.virt.addr;
193
194	/* calculate first value of T */
195	req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
196
197	i = 0;
198	goto first;
199
200	for (;;) {
201		do {
202			for (i = 0; i < nblocks; i++) {
203				gf128mul_x_ble(&t_buf[i], t);
204first:
205				t = &t_buf[i];
206
207				/* PP <- T xor P */
208				be128_xor(dst + i, t, src + i);
209			}
210
211			/* CC <- E(Key2,PP) */
212			req->crypt_fn(req->crypt_ctx, (u8 *)dst,
213				      nblocks * bsize);
214
215			/* C <- T xor CC */
216			for (i = 0; i < nblocks; i++)
217				be128_xor(dst + i, dst + i, &t_buf[i]);
218
219			src += nblocks;
220			dst += nblocks;
221			nbytes -= nblocks * bsize;
222			nblocks = min(nbytes / bsize, max_blks);
223		} while (nblocks > 0);
224
225		*(be128 *)walk.iv = *t;
226
227		err = blkcipher_walk_done(desc, &walk, nbytes);
228		nbytes = walk.nbytes;
229		if (!nbytes)
230			break;
231
232		nblocks = min(nbytes / bsize, max_blks);
233		src = (be128 *)walk.src.virt.addr;
234		dst = (be128 *)walk.dst.virt.addr;
235	}
236
237	return err;
238}
239EXPORT_SYMBOL_GPL(xts_crypt);
240
241static int init_tfm(struct crypto_tfm *tfm)
242{
243	struct crypto_cipher *cipher;
244	struct crypto_instance *inst = (void *)tfm->__crt_alg;
245	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
246	struct priv *ctx = crypto_tfm_ctx(tfm);
247	u32 *flags = &tfm->crt_flags;
248
249	cipher = crypto_spawn_cipher(spawn);
250	if (IS_ERR(cipher))
251		return PTR_ERR(cipher);
252
253	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
254		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
255		crypto_free_cipher(cipher);
256		return -EINVAL;
257	}
258
259	ctx->child = cipher;
260
261	cipher = crypto_spawn_cipher(spawn);
262	if (IS_ERR(cipher)) {
263		crypto_free_cipher(ctx->child);
264		return PTR_ERR(cipher);
265	}
266
267	/* this check isn't really needed, leave it here just in case */
268	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
269		crypto_free_cipher(cipher);
270		crypto_free_cipher(ctx->child);
271		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
272		return -EINVAL;
273	}
274
275	ctx->tweak = cipher;
276
277	return 0;
278}
279
280static void exit_tfm(struct crypto_tfm *tfm)
281{
282	struct priv *ctx = crypto_tfm_ctx(tfm);
283	crypto_free_cipher(ctx->child);
284	crypto_free_cipher(ctx->tweak);
285}
286
287static struct crypto_instance *alloc(struct rtattr **tb)
288{
289	struct crypto_instance *inst;
290	struct crypto_alg *alg;
291	int err;
292
293	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
294	if (err)
295		return ERR_PTR(err);
296
297	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
298				  CRYPTO_ALG_TYPE_MASK);
299	if (IS_ERR(alg))
300		return ERR_CAST(alg);
301
302	inst = crypto_alloc_instance("xts", alg);
303	if (IS_ERR(inst))
304		goto out_put_alg;
305
306	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
307	inst->alg.cra_priority = alg->cra_priority;
308	inst->alg.cra_blocksize = alg->cra_blocksize;
309
310	if (alg->cra_alignmask < 7)
311		inst->alg.cra_alignmask = 7;
312	else
313		inst->alg.cra_alignmask = alg->cra_alignmask;
314
315	inst->alg.cra_type = &crypto_blkcipher_type;
316
317	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
318	inst->alg.cra_blkcipher.min_keysize =
319		2 * alg->cra_cipher.cia_min_keysize;
320	inst->alg.cra_blkcipher.max_keysize =
321		2 * alg->cra_cipher.cia_max_keysize;
322
323	inst->alg.cra_ctxsize = sizeof(struct priv);
324
325	inst->alg.cra_init = init_tfm;
326	inst->alg.cra_exit = exit_tfm;
327
328	inst->alg.cra_blkcipher.setkey = setkey;
329	inst->alg.cra_blkcipher.encrypt = encrypt;
330	inst->alg.cra_blkcipher.decrypt = decrypt;
331
332out_put_alg:
333	crypto_mod_put(alg);
334	return inst;
335}
336
337static void free(struct crypto_instance *inst)
338{
339	crypto_drop_spawn(crypto_instance_ctx(inst));
340	kfree(inst);
341}
342
343static struct crypto_template crypto_tmpl = {
344	.name = "xts",
345	.alloc = alloc,
346	.free = free,
347	.module = THIS_MODULE,
348};
349
350static int __init crypto_module_init(void)
351{
352	return crypto_register_template(&crypto_tmpl);
353}
354
355static void __exit crypto_module_exit(void)
356{
357	crypto_unregister_template(&crypto_tmpl);
358}
359
360module_init(crypto_module_init);
361module_exit(crypto_module_exit);
362
363MODULE_LICENSE("GPL");
364MODULE_DESCRIPTION("XTS block cipher mode");

  1/* XTS: as defined in IEEE1619/D16
  2 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
  3 *	(sector sizes which are not a multiple of 16 bytes are,
  4 *	however currently unsupported)
  5 *
  6 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
  7 *
  8 * Based om ecb.c
  9 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 10 *
 11 * This program is free software; you can redistribute it and/or modify it
 12 * under the terms of the GNU General Public License as published by the Free
 13 * Software Foundation; either version 2 of the License, or (at your option)
 14 * any later version.
 15 */
 16#include <crypto/algapi.h>
 17#include <linux/err.h>
 18#include <linux/init.h>
 19#include <linux/kernel.h>
 20#include <linux/module.h>
 21#include <linux/scatterlist.h>
 22#include <linux/slab.h>
 23
 
 24#include <crypto/b128ops.h>
 25#include <crypto/gf128mul.h>
 26
 27struct priv {
 28	struct crypto_cipher *child;
 29	struct crypto_cipher *tweak;
 30};
 31
 32static int setkey(struct crypto_tfm *parent, const u8 *key,
 33		  unsigned int keylen)
 34{
 35	struct priv *ctx = crypto_tfm_ctx(parent);
 36	struct crypto_cipher *child = ctx->tweak;
 37	u32 *flags = &parent->crt_flags;
 38	int err;
 39
 40	/* key consists of keys of equal size concatenated, therefore
 41	 * the length must be even */
 42	if (keylen % 2) {
 43		/* tell the user why there was an error */
 44		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 45		return -EINVAL;
 46	}
 47
 48	/* we need two cipher instances: one to compute the initial 'tweak'
 49	 * by encrypting the IV (usually the 'plain' iv) and the other
 50	 * one to encrypt and decrypt the data */
 51
 52	/* tweak cipher, uses Key2 i.e. the second half of *key */
 53	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 54	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 55				       CRYPTO_TFM_REQ_MASK);
 56	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
 57	if (err)
 58		return err;
 59
 60	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 61				     CRYPTO_TFM_RES_MASK);
 62
 63	child = ctx->child;
 64
 65	/* data cipher, uses Key1 i.e. the first half of *key */
 66	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 67	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 68				       CRYPTO_TFM_REQ_MASK);
 69	err = crypto_cipher_setkey(child, key, keylen/2);
 70	if (err)
 71		return err;
 72
 73	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 74				     CRYPTO_TFM_RES_MASK);
 75
 76	return 0;
 77}
 78
 79struct sinfo {
 80	be128 *t;
 81	struct crypto_tfm *tfm;
 82	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 83};
 84
 85static inline void xts_round(struct sinfo *s, void *dst, const void *src)
 86{
 87	be128_xor(dst, s->t, src);		/* PP <- T xor P */
 88	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */
 89	be128_xor(dst, dst, s->t);		/* C <- T xor CC */
 90}
 91
 92static int crypt(struct blkcipher_desc *d,
 93		 struct blkcipher_walk *w, struct priv *ctx,
 94		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
 95		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
 96{
 97	int err;
 98	unsigned int avail;
 99	const int bs = crypto_cipher_blocksize(ctx->child);
100	struct sinfo s = {
101		.tfm = crypto_cipher_tfm(ctx->child),
102		.fn = fn
103	};
104	u8 *wsrc;
105	u8 *wdst;
106
107	err = blkcipher_walk_virt(d, w);
108	if (!w->nbytes)
109		return err;
110
111	s.t = (be128 *)w->iv;
112	avail = w->nbytes;
113
114	wsrc = w->src.virt.addr;
115	wdst = w->dst.virt.addr;
116
117	/* calculate first value of T */
118	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
119
120	goto first;
121
122	for (;;) {
123		do {
124			gf128mul_x_ble(s.t, s.t);
125
126first:
127			xts_round(&s, wdst, wsrc);
128
129			wsrc += bs;
130			wdst += bs;
131		} while ((avail -= bs) >= bs);
132
133		err = blkcipher_walk_done(d, w, avail);
134		if (!w->nbytes)
135			break;
136
137		avail = w->nbytes;
138
139		wsrc = w->src.virt.addr;
140		wdst = w->dst.virt.addr;
141	}
142
143	return err;
144}
145
146static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
147		   struct scatterlist *src, unsigned int nbytes)
148{
149	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
150	struct blkcipher_walk w;
151
152	blkcipher_walk_init(&w, dst, src, nbytes);
153	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
154		     crypto_cipher_alg(ctx->child)->cia_encrypt);
155}
156
157static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
158		   struct scatterlist *src, unsigned int nbytes)
159{
160	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
161	struct blkcipher_walk w;
162
163	blkcipher_walk_init(&w, dst, src, nbytes);
164	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
165		     crypto_cipher_alg(ctx->child)->cia_decrypt);
166}
167
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
168static int init_tfm(struct crypto_tfm *tfm)
169{
170	struct crypto_cipher *cipher;
171	struct crypto_instance *inst = (void *)tfm->__crt_alg;
172	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
173	struct priv *ctx = crypto_tfm_ctx(tfm);
174	u32 *flags = &tfm->crt_flags;
175
176	cipher = crypto_spawn_cipher(spawn);
177	if (IS_ERR(cipher))
178		return PTR_ERR(cipher);
179
180	if (crypto_cipher_blocksize(cipher) != 16) {
181		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
182		crypto_free_cipher(cipher);
183		return -EINVAL;
184	}
185
186	ctx->child = cipher;
187
188	cipher = crypto_spawn_cipher(spawn);
189	if (IS_ERR(cipher)) {
190		crypto_free_cipher(ctx->child);
191		return PTR_ERR(cipher);
192	}
193
194	/* this check isn't really needed, leave it here just in case */
195	if (crypto_cipher_blocksize(cipher) != 16) {
196		crypto_free_cipher(cipher);
197		crypto_free_cipher(ctx->child);
198		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
199		return -EINVAL;
200	}
201
202	ctx->tweak = cipher;
203
204	return 0;
205}
206
207static void exit_tfm(struct crypto_tfm *tfm)
208{
209	struct priv *ctx = crypto_tfm_ctx(tfm);
210	crypto_free_cipher(ctx->child);
211	crypto_free_cipher(ctx->tweak);
212}
213
214static struct crypto_instance *alloc(struct rtattr **tb)
215{
216	struct crypto_instance *inst;
217	struct crypto_alg *alg;
218	int err;
219
220	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
221	if (err)
222		return ERR_PTR(err);
223
224	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
225				  CRYPTO_ALG_TYPE_MASK);
226	if (IS_ERR(alg))
227		return ERR_CAST(alg);
228
229	inst = crypto_alloc_instance("xts", alg);
230	if (IS_ERR(inst))
231		goto out_put_alg;
232
233	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
234	inst->alg.cra_priority = alg->cra_priority;
235	inst->alg.cra_blocksize = alg->cra_blocksize;
236
237	if (alg->cra_alignmask < 7)
238		inst->alg.cra_alignmask = 7;
239	else
240		inst->alg.cra_alignmask = alg->cra_alignmask;
241
242	inst->alg.cra_type = &crypto_blkcipher_type;
243
244	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
245	inst->alg.cra_blkcipher.min_keysize =
246		2 * alg->cra_cipher.cia_min_keysize;
247	inst->alg.cra_blkcipher.max_keysize =
248		2 * alg->cra_cipher.cia_max_keysize;
249
250	inst->alg.cra_ctxsize = sizeof(struct priv);
251
252	inst->alg.cra_init = init_tfm;
253	inst->alg.cra_exit = exit_tfm;
254
255	inst->alg.cra_blkcipher.setkey = setkey;
256	inst->alg.cra_blkcipher.encrypt = encrypt;
257	inst->alg.cra_blkcipher.decrypt = decrypt;
258
259out_put_alg:
260	crypto_mod_put(alg);
261	return inst;
262}
263
264static void free(struct crypto_instance *inst)
265{
266	crypto_drop_spawn(crypto_instance_ctx(inst));
267	kfree(inst);
268}
269
270static struct crypto_template crypto_tmpl = {
271	.name = "xts",
272	.alloc = alloc,
273	.free = free,
274	.module = THIS_MODULE,
275};
276
277static int __init crypto_module_init(void)
278{
279	return crypto_register_template(&crypto_tmpl);
280}
281
282static void __exit crypto_module_exit(void)
283{
284	crypto_unregister_template(&crypto_tmpl);
285}
286
287module_init(crypto_module_init);
288module_exit(crypto_module_exit);
289
290MODULE_LICENSE("GPL");
291MODULE_DESCRIPTION("XTS block cipher mode");