[linux.git] / crypto / lrw.c

/* LRW: as defined by Cyril Guyot in
 *	http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
 *
 * Copyright (c) 2006 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.
 */
/* This implementation is checked against the test vectors in the above
 * document and by a test vector provided by Ken Buchanan at
 * http://www.mail-archive.com/[email protected]/msg00173.html
 *
 * The test vectors are included in the testing module tcrypt.[ch] */
#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;
	/* optimizes multiplying a random (non incrementing, as at the
	 * start of a new sector) value with key2, we could also have
	 * used 4k optimization tables or no optimization at all. In the
	 * latter case we would have to store key2 here */
	struct gf128mul_64k *table;
	/* stores:
	 *  key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
	 *  key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
	 *  key2*{ 0,0,...1,1,1,1,1 }, etc
	 * needed for optimized multiplication of incrementing values
	 * with key2 */
	be128 mulinc[128];
};

static inline void setbit128_bbe(void *b, int bit)
{
	__set_bit(bit ^ 0x78, b);
}

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->child;
	int err, i;
	be128 tmp = { 0 };
	int bsize = crypto_cipher_blocksize(child);

	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
				       CRYPTO_TFM_REQ_MASK);
	if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
		return err;
	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
				     CRYPTO_TFM_RES_MASK);

	if (ctx->table)
		gf128mul_free_64k(ctx->table);

	/* initialize multiplication table for Key2 */
	ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
	if (!ctx->table)
		return -ENOMEM;

	/* initialize optimization table */
	for (i = 0; i < 128; i++) {
		setbit128_bbe(&tmp, i);
		ctx->mulinc[i] = tmp;
		gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
	}

	return 0;
}

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

static inline void inc(be128 *iv)
{
	be64_add_cpu(&iv->b, 1);
	if (!iv->b)
		be64_add_cpu(&iv->a, 1);
}

static inline void lrw_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(Key2,PP) */
	be128_xor(dst, dst, &s->t);		/* C <- T xor CC */
}

/* this returns the number of consequative 1 bits starting
 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
static inline int get_index128(be128 *block)
{
	int x;
	__be32 *p = (__be32 *) block;

	for (p += 3, x = 0; x < 128; p--, x += 32) {
		u32 val = be32_to_cpup(p);

		if (!~val)
			continue;

		return x + ffz(val);
	}

	return x;
}

static int crypt(struct blkcipher_desc *d,
		 struct blkcipher_walk *w, struct priv *ctx,
		 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 (!(avail = w->nbytes))
		return err;

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

	/* calculate first value of T */
	iv = (be128 *)w->iv;
	s.t = *iv;

	/* T <- I*Key2 */
	gf128mul_64k_bbe(&s.t, ctx->table);

	goto first;

	for (;;) {
		do {
			/* T <- I*Key2, using the optimization
			 * discussed in the specification */
			be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
			inc(iv);

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

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

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

		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->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->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;
		return -EINVAL;
	}

	ctx->child = cipher;
	return 0;
}

static void exit_tfm(struct crypto_tfm *tfm)
{
	struct priv *ctx = crypto_tfm_ctx(tfm);
	if (ctx->table)
		gf128mul_free_64k(ctx->table);
	crypto_free_cipher(ctx->child);
}

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_CAST(alg);

	inst = crypto_alloc_instance("lrw", 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;

	if (!(alg->cra_blocksize % 4))
		inst->alg.cra_alignmask |= 3;
	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	inst->alg.cra_blkcipher.min_keysize =
		alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
	inst->alg.cra_blkcipher.max_keysize =
		alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;

	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 = "lrw",
	.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("LRW block cipher mode");
Commit	Line	Data
64470f1b RS	1	/* LRW: as defined by Cyril Guyot in
	2	* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
	3	*
	4	* Copyright (c) 2006 Rik Snel <[email protected]>
	5	*
	6	* Based om ecb.c
	7	* Copyright (c) 2006 Herbert Xu <[email protected]>
	8	*
	9	* This program is free software; you can redistribute it and/or modify it
	10	* under the terms of the GNU General Public License as published by the Free
	11	* Software Foundation; either version 2 of the License, or (at your option)
	12	* any later version.
	13	*/
	14	/* This implementation is checked against the test vectors in the above
	15	* document and by a test vector provided by Ken Buchanan at
	16	* http://www.mail-archive.com/[email protected]/msg00173.html
	17	*
	18	* The test vectors are included in the testing module tcrypt.[ch] */
	19	#include <crypto/algapi.h>
	20	#include <linux/err.h>
	21	#include <linux/init.h>
	22	#include <linux/kernel.h>
	23	#include <linux/module.h>
	24	#include <linux/scatterlist.h>
	25	#include <linux/slab.h>
	26
	27	#include <crypto/b128ops.h>
	28	#include <crypto/gf128mul.h>
	29
	30	struct priv {
	31	struct crypto_cipher *child;
	32	/* optimizes multiplying a random (non incrementing, as at the
	33	* start of a new sector) value with key2, we could also have
	34	* used 4k optimization tables or no optimization at all. In the
	35	* latter case we would have to store key2 here */
	36	struct gf128mul_64k *table;
	37	/* stores:
	38	* key2{ 0,0,...0,0,0,0,1 }, key2{ 0,0,...0,0,0,1,1 },
	39	* key2{ 0,0,...0,0,1,1,1 }, key2{ 0,0,...0,1,1,1,1 }
	40	* key2*{ 0,0,...1,1,1,1,1 }, etc
	41	* needed for optimized multiplication of incrementing values
	42	* with key2 */
	43	be128 mulinc[128];
	44	};
	45
	46	static inline void setbit128_bbe(void *b, int bit)
	47	{
	48	__set_bit(bit ^ 0x78, b);
	49	}
	50
	51	static int setkey(struct crypto_tfm parent, const u8 key,
	52	unsigned int keylen)
	53	{
	54	struct priv *ctx = crypto_tfm_ctx(parent);
	55	struct crypto_cipher *child = ctx->child;
	56	int err, i;
	57	be128 tmp = { 0 };
	58	int bsize = crypto_cipher_blocksize(child);
	59
	60	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	61	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
	62	CRYPTO_TFM_REQ_MASK);
	63	if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
	64	return err;
65	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
66	CRYPTO_TFM_RES_MASK);
67
68	if (ctx->table)
69	gf128mul_free_64k(ctx->table);
70
71	/* initialize multiplication table for Key2 */
72	ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
73	if (!ctx->table)
74	return -ENOMEM;
75
76	/* initialize optimization table */
77	for (i = 0; i < 128; i++) {
78	setbit128_bbe(&tmp, i);
79	ctx->mulinc[i] = tmp;
80	gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
81	}
82
83	return 0;
84	}
85
86	struct sinfo {
87	be128 t;
88	struct crypto_tfm *tfm;
89	void (fn)(struct crypto_tfm , u8 , const u8 );
90	};
91
92	static inline void inc(be128 *iv)
93	{
fd4609a8 MS	94	be64_add_cpu(&iv->b, 1);
	95	if (!iv->b)
	96	be64_add_cpu(&iv->a, 1);
64470f1b RS	97	}
64470f1b RS	98
9ebed9d1	99	static inline void lrw_round(struct sinfo s, void dst, const void *src)
64470f1b RS	100	{
	101	be128_xor(dst, &s->t, src); /* PP <- T xor P */
	102	s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
	103	be128_xor(dst, dst, &s->t); /* C <- T xor CC */
	104	}
	105
	106	/* this returns the number of consequative 1 bits starting
	107	* from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
	108	static inline int get_index128(be128 *block)
	109	{
	110	int x;
	111	__be32 p = (__be32 ) block;
	112
	113	for (p += 3, x = 0; x < 128; p--, x += 32) {
	114	u32 val = be32_to_cpup(p);
	115
	116	if (!~val)
	117	continue;
	118
	119	return x + ffz(val);
	120	}
	121
	122	return x;
	123	}
	124
	125	static int crypt(struct blkcipher_desc *d,
	126	struct blkcipher_walk w, struct priv ctx,
	127	void (fn)(struct crypto_tfm , u8 , const u8 ))
	128	{
	129	int err;
	130	unsigned int avail;
	131	const int bs = crypto_cipher_blocksize(ctx->child);
	132	struct sinfo s = {
	133	.tfm = crypto_cipher_tfm(ctx->child),
	134	.fn = fn
	135	};
	136	be128 *iv;
	137	u8 *wsrc;
	138	u8 *wdst;
	139
	140	err = blkcipher_walk_virt(d, w);
	141	if (!(avail = w->nbytes))
	142	return err;
	143
	144	wsrc = w->src.virt.addr;
	145	wdst = w->dst.virt.addr;
	146
	147	/* calculate first value of T */
	148	iv = (be128 *)w->iv;
	149	s.t = *iv;
	150
	151	/* T <- IKey2 /
	152	gf128mul_64k_bbe(&s.t, ctx->table);
	153
	154	goto first;
	155
	156	for (;;) {
	157	do {
	158	/* T <- I*Key2, using the optimization
	159	* discussed in the specification */
	160	be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
	161	inc(iv);
	162
	163	first:
9ebed9d1	164	lrw_round(&s, wdst, wsrc);
64470f1b RS	165
	166	wsrc += bs;
	167	wdst += bs;
	168	} while ((avail -= bs) >= bs);
	169
	170	err = blkcipher_walk_done(d, w, avail);
	171	if (!(avail = w->nbytes))
	172	break;
	173
	174	wsrc = w->src.virt.addr;
	175	wdst = w->dst.virt.addr;
	176	}
	177
	178	return err;
	179	}
	180
	181	static int encrypt(struct blkcipher_desc desc, struct scatterlist dst,
	182	struct scatterlist *src, unsigned int nbytes)
	183	{
	184	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	185	struct blkcipher_walk w;
	186
	187	blkcipher_walk_init(&w, dst, src, nbytes);
	188	return crypt(desc, &w, ctx,
	189	crypto_cipher_alg(ctx->child)->cia_encrypt);
	190	}
	191
	192	static int decrypt(struct blkcipher_desc desc, struct scatterlist dst,
	193	struct scatterlist *src, unsigned int nbytes)
	194	{
	195	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	196	struct blkcipher_walk w;
	197
	198	blkcipher_walk_init(&w, dst, src, nbytes);
	199	return crypt(desc, &w, ctx,
	200	crypto_cipher_alg(ctx->child)->cia_decrypt);
	201	}
	202
	203	static int init_tfm(struct crypto_tfm *tfm)
	204	{
2e306ee0	205	struct crypto_cipher *cipher;
64470f1b RS	206	struct crypto_instance inst = (void )tfm->__crt_alg;
	207	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	208	struct priv *ctx = crypto_tfm_ctx(tfm);
	209	u32 *flags = &tfm->crt_flags;
	210
2e306ee0 HX	211	cipher = crypto_spawn_cipher(spawn);
	212	if (IS_ERR(cipher))
	213	return PTR_ERR(cipher);
64470f1b	214
2e306ee0	215	if (crypto_cipher_blocksize(cipher) != 16) {
64470f1b RS	216	*flags \|= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
	217	return -EINVAL;
	218	}
	219
2e306ee0	220	ctx->child = cipher;
64470f1b RS	221	return 0;
	222	}
	223
	224	static void exit_tfm(struct crypto_tfm *tfm)
	225	{
	226	struct priv *ctx = crypto_tfm_ctx(tfm);
	227	if (ctx->table)
	228	gf128mul_free_64k(ctx->table);
	229	crypto_free_cipher(ctx->child);
	230	}
	231
ebc610e5	232	static struct crypto_instance alloc(struct rtattr *tb)
64470f1b RS	233	{
	234	struct crypto_instance *inst;
	235	struct crypto_alg *alg;
ebc610e5 HX	236	int err;
	237
	238	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	239	if (err)
	240	return ERR_PTR(err);
64470f1b	241
ebc610e5 HX	242	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
ebc610e5 HX	243	CRYPTO_ALG_TYPE_MASK);
64470f1b	244	if (IS_ERR(alg))
e231c2ee	245	return ERR_CAST(alg);
64470f1b RS	246
	247	inst = crypto_alloc_instance("lrw", alg);
	248	if (IS_ERR(inst))
	249	goto out_put_alg;
	250
	251	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	252	inst->alg.cra_priority = alg->cra_priority;
	253	inst->alg.cra_blocksize = alg->cra_blocksize;
	254
	255	if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
	256	else inst->alg.cra_alignmask = alg->cra_alignmask;
	257	inst->alg.cra_type = &crypto_blkcipher_type;
	258
	259	if (!(alg->cra_blocksize % 4))
	260	inst->alg.cra_alignmask \|= 3;
	261	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	262	inst->alg.cra_blkcipher.min_keysize =
	263	alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
	264	inst->alg.cra_blkcipher.max_keysize =
	265	alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
	266
	267	inst->alg.cra_ctxsize = sizeof(struct priv);
	268
	269	inst->alg.cra_init = init_tfm;
	270	inst->alg.cra_exit = exit_tfm;
	271
	272	inst->alg.cra_blkcipher.setkey = setkey;
	273	inst->alg.cra_blkcipher.encrypt = encrypt;
	274	inst->alg.cra_blkcipher.decrypt = decrypt;
	275
	276	out_put_alg:
	277	crypto_mod_put(alg);
	278	return inst;
	279	}
	280
	281	static void free(struct crypto_instance *inst)
	282	{
	283	crypto_drop_spawn(crypto_instance_ctx(inst));
	284	kfree(inst);
	285	}
	286
	287	static struct crypto_template crypto_tmpl = {
	288	.name = "lrw",
	289	.alloc = alloc,
	290	.free = free,
	291	.module = THIS_MODULE,
	292	};
	293
	294	static int __init crypto_module_init(void)
	295	{
	296	return crypto_register_template(&crypto_tmpl);
	297	}
	298
	299	static void __exit crypto_module_exit(void)
	300	{
	301	crypto_unregister_template(&crypto_tmpl);
	302	}
	303
	304	module_init(crypto_module_init);
	305	module_exit(crypto_module_exit);
	306
	307	MODULE_LICENSE("GPL");
	308	MODULE_DESCRIPTION("LRW block cipher mode");