[mirror_ubuntu-zesty-kernel.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 <rsnel@cube.dyndns.org>
 *
 * Based om ecb.c
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * 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
	};
	be128 *iv;
	u8 *wsrc;
	u8 *wdst;

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

	avail = w->nbytes;

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

	/* calculate first value of T */
	iv = (be128 *)w->iv;
	tw(crypto_cipher_tfm(ctx->tweak), (void *)&s.t, 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 <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
	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 {
80	be128 t;
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	{
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
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	};
104	be128 *iv;
105	u8 *wsrc;
106	u8 *wdst;
107
108	err = blkcipher_walk_virt(d, w);
109	if (!w->nbytes)
110	return err;
111
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	iv = (be128 *)w->iv;
119	tw(crypto_cipher_tfm(ctx->tweak), (void *)&s.t, w->iv);
120
121	goto first;
122
123	for (;;) {
124	do {
125	gf128mul_x_ble(&s.t, &s.t);
126
127	first:
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
147	static 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
158	static 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
169	static int init_tfm(struct crypto_tfm *tfm)
170	{
171	struct crypto_cipher *cipher;
172	struct crypto_instance inst = (void )tfm->__crt_alg;
173	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
174	struct priv *ctx = crypto_tfm_ctx(tfm);
175	u32 *flags = &tfm->crt_flags;
176
177	cipher = crypto_spawn_cipher(spawn);
178	if (IS_ERR(cipher))
179	return PTR_ERR(cipher);
180
181	if (crypto_cipher_blocksize(cipher) != 16) {
182	*flags \|= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
183	crypto_free_cipher(cipher);
184	return -EINVAL;
185	}
186
187	ctx->child = cipher;
188
189	cipher = crypto_spawn_cipher(spawn);
190	if (IS_ERR(cipher)) {
191	crypto_free_cipher(ctx->child);
192	return PTR_ERR(cipher);
193	}
194
195	/* this check isn't really needed, leave it here just in case */
196	if (crypto_cipher_blocksize(cipher) != 16) {
197	crypto_free_cipher(cipher);
198	crypto_free_cipher(ctx->child);
199	*flags \|= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
200	return -EINVAL;
201	}
202
203	ctx->tweak = cipher;
204
205	return 0;
206	}
207
208	static void exit_tfm(struct crypto_tfm *tfm)
209	{
210	struct priv *ctx = crypto_tfm_ctx(tfm);
211	crypto_free_cipher(ctx->child);
212	crypto_free_cipher(ctx->tweak);
213	}
214
215	static struct crypto_instance alloc(struct rtattr *tb)
216	{
217	struct crypto_instance *inst;
218	struct crypto_alg *alg;
219	int err;
220
221	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
222	if (err)
223	return ERR_PTR(err);
224
225	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
226	CRYPTO_ALG_TYPE_MASK);
227	if (IS_ERR(alg))
228	return ERR_PTR(PTR_ERR(alg));
229
230	inst = crypto_alloc_instance("xts", alg);
231	if (IS_ERR(inst))
232	goto out_put_alg;
233
234	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
235	inst->alg.cra_priority = alg->cra_priority;
236	inst->alg.cra_blocksize = alg->cra_blocksize;
237
238	if (alg->cra_alignmask < 7)
239	inst->alg.cra_alignmask = 7;
240	else
241	inst->alg.cra_alignmask = alg->cra_alignmask;
242
243	inst->alg.cra_type = &crypto_blkcipher_type;
244
245	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
246	inst->alg.cra_blkcipher.min_keysize =
247	2 * alg->cra_cipher.cia_min_keysize;
248	inst->alg.cra_blkcipher.max_keysize =
249	2 * alg->cra_cipher.cia_max_keysize;
250
251	inst->alg.cra_ctxsize = sizeof(struct priv);
252
253	inst->alg.cra_init = init_tfm;
254	inst->alg.cra_exit = exit_tfm;
255
256	inst->alg.cra_blkcipher.setkey = setkey;
257	inst->alg.cra_blkcipher.encrypt = encrypt;
258	inst->alg.cra_blkcipher.decrypt = decrypt;
259
260	out_put_alg:
261	crypto_mod_put(alg);
262	return inst;
263	}
264
265	static void free(struct crypto_instance *inst)
266	{
267	crypto_drop_spawn(crypto_instance_ctx(inst));
268	kfree(inst);
269	}
270
271	static struct crypto_template crypto_tmpl = {
272	.name = "xts",
273	.alloc = alloc,
274	.free = free,
275	.module = THIS_MODULE,
276	};
277
278	static int __init crypto_module_init(void)
279	{
280	return crypto_register_template(&crypto_tmpl);
281	}
282
283	static void __exit crypto_module_exit(void)
284	{
285	crypto_unregister_template(&crypto_tmpl);
286	}
287
288	module_init(crypto_module_init);
289	module_exit(crypto_module_exit);
290
291	MODULE_LICENSE("GPL");
292	MODULE_DESCRIPTION("XTS block cipher mode");