[linux.git] / crypto / xts.c

/* XTS: as defined in IEEE1619/D16
 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
 *	(sector sizes which are not a multiple of 16 bytes are,
 *	however currently unsupported)
 *
 * Copyright (c) 2007 Rik Snel <[email protected]>
 *
 * Based om ecb.c
 * Copyright (c) 2006 Herbert Xu <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */
#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>

struct priv {
	struct crypto_cipher *child;
	struct crypto_cipher *tweak;
};

static int setkey(struct crypto_tfm *parent, const u8 *key,
		  unsigned int keylen)
{
	struct priv *ctx = crypto_tfm_ctx(parent);
	struct crypto_cipher *child = ctx->tweak;
	u32 *flags = &parent->crt_flags;
	int err;

	/* key consists of keys of equal size concatenated, therefore
	 * the length must be even */
	if (keylen % 2) {
		/* tell the user why there was an error */
		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}

	/* we need two cipher instances: one to compute the inital 'tweak'
	 * by encrypting the IV (usually the 'plain' iv) and the other
	 * one to encrypt and decrypt the data */

	/* tweak cipher, uses Key2 i.e. the second half of *key */
	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
				       CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
	if (err)
		return err;

	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
				     CRYPTO_TFM_RES_MASK);

	child = ctx->child;

	/* data cipher, uses Key1 i.e. the first half of *key */
	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
				       CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key, keylen/2);
	if (err)
		return err;

	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
				     CRYPTO_TFM_RES_MASK);

	return 0;
}

struct sinfo {
	be128 *t;
	struct crypto_tfm *tfm;
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
};

static inline void xts_round(struct sinfo *s, void *dst, const void *src)
{
	be128_xor(dst, s->t, src);		/* PP <- T xor P */
	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */
	be128_xor(dst, dst, s->t);		/* C <- T xor CC */
}

static int crypt(struct blkcipher_desc *d,
		 struct blkcipher_walk *w, struct priv *ctx,
		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
{
	int err;
	unsigned int avail;
	const int bs = crypto_cipher_blocksize(ctx->child);
	struct sinfo s = {
		.tfm = crypto_cipher_tfm(ctx->child),
		.fn = fn
	};
	u8 *wsrc;
	u8 *wdst;

	err = blkcipher_walk_virt(d, w);
	if (!w->nbytes)
		return err;

	s.t = (be128 *)w->iv;
	avail = w->nbytes;

	wsrc = w->src.virt.addr;
	wdst = w->dst.virt.addr;

	/* calculate first value of T */
	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);

	goto first;

	for (;;) {
		do {
			gf128mul_x_ble(s.t, s.t);

first:
			xts_round(&s, wdst, wsrc);

			wsrc += bs;
			wdst += bs;
		} while ((avail -= bs) >= bs);

		err = blkcipher_walk_done(d, w, avail);
		if (!w->nbytes)
			break;

		avail = w->nbytes;

		wsrc = w->src.virt.addr;
		wdst = w->dst.virt.addr;
	}

	return err;
}

static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		   struct scatterlist *src, unsigned int nbytes)
{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
		     crypto_cipher_alg(ctx->child)->cia_encrypt);
}

static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		   struct scatterlist *src, unsigned int nbytes)
{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
		     crypto_cipher_alg(ctx->child)->cia_decrypt);
}

static int init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_cipher *cipher;
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	struct priv *ctx = crypto_tfm_ctx(tfm);
	u32 *flags = &tfm->crt_flags;

	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	if (crypto_cipher_blocksize(cipher) != 16) {
		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
		crypto_free_cipher(cipher);
		return -EINVAL;
	}

	ctx->child = cipher;

	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher)) {
		crypto_free_cipher(ctx->child);
		return PTR_ERR(cipher);
	}

	/* this check isn't really needed, leave it here just in case */
	if (crypto_cipher_blocksize(cipher) != 16) {
		crypto_free_cipher(cipher);
		crypto_free_cipher(ctx->child);
		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
		return -EINVAL;
	}

	ctx->tweak = cipher;

	return 0;
}

static void exit_tfm(struct crypto_tfm *tfm)
{
	struct priv *ctx = crypto_tfm_ctx(tfm);
	crypto_free_cipher(ctx->child);
	crypto_free_cipher(ctx->tweak);
}

static struct crypto_instance *alloc(struct rtattr **tb)
{
	struct crypto_instance *inst;
	struct crypto_alg *alg;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	if (err)
		return ERR_PTR(err);

	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
				  CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
		return ERR_PTR(PTR_ERR(alg));

	inst = crypto_alloc_instance("xts", alg);
	if (IS_ERR(inst))
		goto out_put_alg;

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = alg->cra_blocksize;

	if (alg->cra_alignmask < 7)
		inst->alg.cra_alignmask = 7;
	else
		inst->alg.cra_alignmask = alg->cra_alignmask;

	inst->alg.cra_type = &crypto_blkcipher_type;

	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	inst->alg.cra_blkcipher.min_keysize =
		2 * alg->cra_cipher.cia_min_keysize;
	inst->alg.cra_blkcipher.max_keysize =
		2 * alg->cra_cipher.cia_max_keysize;

	inst->alg.cra_ctxsize = sizeof(struct priv);

	inst->alg.cra_init = init_tfm;
	inst->alg.cra_exit = exit_tfm;

	inst->alg.cra_blkcipher.setkey = setkey;
	inst->alg.cra_blkcipher.encrypt = encrypt;
	inst->alg.cra_blkcipher.decrypt = decrypt;

out_put_alg:
	crypto_mod_put(alg);
	return inst;
}

static void free(struct crypto_instance *inst)
{
	crypto_drop_spawn(crypto_instance_ctx(inst));
	kfree(inst);
}

static struct crypto_template crypto_tmpl = {
	.name = "xts",
	.alloc = alloc,
	.free = free,
	.module = THIS_MODULE,
};

static int __init crypto_module_init(void)
{
	return crypto_register_template(&crypto_tmpl);
}

static void __exit crypto_module_exit(void)
{
	crypto_unregister_template(&crypto_tmpl);
}

module_init(crypto_module_init);
module_exit(crypto_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XTS block cipher mode");
Commit	Line	Data
f19f5111 RS	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 <[email protected]>
	7	*
	8	* Based om ecb.c
	9	* Copyright (c) 2006 Herbert Xu <[email protected]>
	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
	27	struct priv {
	28	struct crypto_cipher *child;
	29	struct crypto_cipher *tweak;
	30	};
	31
	32	static 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 inital '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
79	struct sinfo {
6212f2c7	80	be128 *t;
f19f5111 RS	81	struct crypto_tfm *tfm;
	82	void (fn)(struct crypto_tfm , u8 , const u8 );
	83	};
	84
	85	static inline void xts_round(struct sinfo s, void dst, const void *src)
	86	{
6212f2c7	87	be128_xor(dst, s->t, src); /* PP <- T xor P */
f19f5111	88	s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
6212f2c7	89	be128_xor(dst, dst, s->t); /* C <- T xor CC */
f19f5111 RS	90	}
	91
	92	static 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	};
f19f5111 RS	104	u8 *wsrc;
	105	u8 *wdst;
	106
	107	err = blkcipher_walk_virt(d, w);
	108	if (!w->nbytes)
	109	return err;
	110
6212f2c7	111	s.t = (be128 *)w->iv;
f19f5111 RS	112	avail = w->nbytes;
	113
	114	wsrc = w->src.virt.addr;
	115	wdst = w->dst.virt.addr;
	116
	117	/* calculate first value of T */
6212f2c7	118	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
f19f5111 RS	119
	120	goto first;
	121
	122	for (;;) {
	123	do {
6212f2c7	124	gf128mul_x_ble(s.t, s.t);
f19f5111 RS	125
	126	first:
	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
	146	static 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
	157	static 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
	168	static 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
207	static 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
214	static 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_PTR(PTR_ERR(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
259	out_put_alg:
260	crypto_mod_put(alg);
261	return inst;
262	}
263
264	static void free(struct crypto_instance *inst)
265	{
266	crypto_drop_spawn(crypto_instance_ctx(inst));
267	kfree(inst);
268	}
269
270	static struct crypto_template crypto_tmpl = {
271	.name = "xts",
272	.alloc = alloc,
273	.free = free,
274	.module = THIS_MODULE,
275	};
276
277	static int __init crypto_module_init(void)
278	{
279	return crypto_register_template(&crypto_tmpl);
280	}
281
282	static void __exit crypto_module_exit(void)
283	{
284	crypto_unregister_template(&crypto_tmpl);
285	}
286
287	module_init(crypto_module_init);
288	module_exit(crypto_module_exit);
289
290	MODULE_LICENSE("GPL");
291	MODULE_DESCRIPTION("XTS block cipher mode");