[linux-block.git] / crypto / lrw.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* LRW: as defined by Cyril Guyot in
 *	http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
 *
 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 */
/* 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/stds-p1619@listserv.ieee.org/msg00173.html
 *
 * The test vectors are included in the testing module tcrypt.[ch] */

#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.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>

#define LRW_BLOCK_SIZE 16

struct priv {
	struct crypto_skcipher *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];
};

struct rctx {
	be128 t;
	struct skcipher_request subreq;
};

static inline void setbit128_bbe(void *b, int bit)
{
	__set_bit(bit ^ (0x80 -
#ifdef __BIG_ENDIAN
			 BITS_PER_LONG
#else
			 BITS_PER_BYTE
#endif
			), b);
}

static int setkey(struct crypto_skcipher *parent, const u8 *key,
		  unsigned int keylen)
{
	struct priv *ctx = crypto_skcipher_ctx(parent);
	struct crypto_skcipher *child = ctx->child;
	int err, bsize = LRW_BLOCK_SIZE;
	const u8 *tweak = key + keylen - bsize;
	be128 tmp = { 0 };
	int i;

	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
					 CRYPTO_TFM_REQ_MASK);
	err = crypto_skcipher_setkey(child, key, keylen - bsize);
	if (err)
		return err;

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

	/* initialize multiplication table for Key2 */
	ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
	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;
}

/*
 * Returns the number of trailing '1' bits in the words of the counter, which is
 * represented by 4 32-bit words, arranged from least to most significant.
 * At the same time, increments the counter by one.
 *
 * For example:
 *
 * u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
 * int i = next_index(&counter);
 * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
 */
static int next_index(u32 *counter)
{
	int i, res = 0;

	for (i = 0; i < 4; i++) {
		if (counter[i] + 1 != 0)
			return res + ffz(counter[i]++);

		counter[i] = 0;
		res += 32;
	}

	/*
	 * If we get here, then x == 128 and we are incrementing the counter
	 * from all ones to all zeros. This means we must return index 127, i.e.
	 * the one corresponding to key2*{ 1,...,1 }.
	 */
	return 127;
}

/*
 * We compute the tweak masks twice (both before and after the ECB encryption or
 * decryption) to avoid having to allocate a temporary buffer and/or make
 * mutliple calls to the 'ecb(..)' instance, which usually would be slower than
 * just doing the next_index() calls again.
 */
static int xor_tweak(struct skcipher_request *req, bool second_pass)
{
	const int bs = LRW_BLOCK_SIZE;
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct priv *ctx = crypto_skcipher_ctx(tfm);
	struct rctx *rctx = skcipher_request_ctx(req);
	be128 t = rctx->t;
	struct skcipher_walk w;
	__be32 *iv;
	u32 counter[4];
	int err;

	if (second_pass) {
		req = &rctx->subreq;
		/* set to our TFM to enforce correct alignment: */
		skcipher_request_set_tfm(req, tfm);
	}

	err = skcipher_walk_virt(&w, req, false);
	if (err)
		return err;

	iv = (__be32 *)w.iv;
	counter[0] = be32_to_cpu(iv[3]);
	counter[1] = be32_to_cpu(iv[2]);
	counter[2] = be32_to_cpu(iv[1]);
	counter[3] = be32_to_cpu(iv[0]);

	while (w.nbytes) {
		unsigned int avail = w.nbytes;
		be128 *wsrc;
		be128 *wdst;

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

		do {
			be128_xor(wdst++, &t, wsrc++);

			/* T <- I*Key2, using the optimization
			 * discussed in the specification */
			be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
		} while ((avail -= bs) >= bs);

		if (second_pass && w.nbytes == w.total) {
			iv[0] = cpu_to_be32(counter[3]);
			iv[1] = cpu_to_be32(counter[2]);
			iv[2] = cpu_to_be32(counter[1]);
			iv[3] = cpu_to_be32(counter[0]);
		}

		err = skcipher_walk_done(&w, avail);
	}

	return err;
}

static int xor_tweak_pre(struct skcipher_request *req)
{
	return xor_tweak(req, false);
}

static int xor_tweak_post(struct skcipher_request *req)
{
	return xor_tweak(req, true);
}

static void crypt_done(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->data;

	if (!err) {
		struct rctx *rctx = skcipher_request_ctx(req);

		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
		err = xor_tweak_post(req);
	}

	skcipher_request_complete(req, err);
}

static void init_crypt(struct skcipher_request *req)
{
	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	skcipher_request_set_tfm(subreq, ctx->child);
	skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
	/* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
	skcipher_request_set_crypt(subreq, req->dst, req->dst,
				   req->cryptlen, req->iv);

	/* calculate first value of T */
	memcpy(&rctx->t, req->iv, sizeof(rctx->t));

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

static int encrypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	init_crypt(req);
	return xor_tweak_pre(req) ?:
		crypto_skcipher_encrypt(subreq) ?:
		xor_tweak_post(req);
}

static int decrypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	init_crypt(req);
	return xor_tweak_pre(req) ?:
		crypto_skcipher_decrypt(subreq) ?:
		xor_tweak_post(req);
}

static int init_tfm(struct crypto_skcipher *tfm)
{
	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
	struct priv *ctx = crypto_skcipher_ctx(tfm);
	struct crypto_skcipher *cipher;

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

	ctx->child = cipher;

	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
					 sizeof(struct rctx));

	return 0;
}

static void exit_tfm(struct crypto_skcipher *tfm)
{
	struct priv *ctx = crypto_skcipher_ctx(tfm);

	if (ctx->table)
		gf128mul_free_64k(ctx->table);
	crypto_free_skcipher(ctx->child);
}

static void crypto_lrw_free(struct skcipher_instance *inst)
{
	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	kfree(inst);
}

static int create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct crypto_skcipher_spawn *spawn;
	struct skcipher_instance *inst;
	struct skcipher_alg *alg;
	const char *cipher_name;
	char ecb_name[CRYPTO_MAX_ALG_NAME];
	u32 mask;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
	if (err)
		return err;

	cipher_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(cipher_name))
		return PTR_ERR(cipher_name);

	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
	if (!inst)
		return -ENOMEM;

	spawn = skcipher_instance_ctx(inst);

	err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),
				   cipher_name, 0, mask);
	if (err == -ENOENT) {
		err = -ENAMETOOLONG;
		if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
			     cipher_name) >= CRYPTO_MAX_ALG_NAME)
			goto err_free_inst;

		err = crypto_grab_skcipher(spawn,
					   skcipher_crypto_instance(inst),
					   ecb_name, 0, mask);
	}

	if (err)
		goto err_free_inst;

	alg = crypto_skcipher_spawn_alg(spawn);

	err = -EINVAL;
	if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
		goto err_free_inst;

	if (crypto_skcipher_alg_ivsize(alg))
		goto err_free_inst;

	err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
				  &alg->base);
	if (err)
		goto err_free_inst;

	err = -EINVAL;
	cipher_name = alg->base.cra_name;

	/* Alas we screwed up the naming so we have to mangle the
	 * cipher name.
	 */
	if (!strncmp(cipher_name, "ecb(", 4)) {
		unsigned len;

		len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
		if (len < 2 || len >= sizeof(ecb_name))
			goto err_free_inst;

		if (ecb_name[len - 1] != ')')
			goto err_free_inst;

		ecb_name[len - 1] = 0;

		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
			     "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
			err = -ENAMETOOLONG;
			goto err_free_inst;
		}
	} else
		goto err_free_inst;

	inst->alg.base.cra_priority = alg->base.cra_priority;
	inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
				       (__alignof__(be128) - 1);

	inst->alg.ivsize = LRW_BLOCK_SIZE;
	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
				LRW_BLOCK_SIZE;
	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
				LRW_BLOCK_SIZE;

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

	inst->alg.init = init_tfm;
	inst->alg.exit = exit_tfm;

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

	inst->free = crypto_lrw_free;

	err = skcipher_register_instance(tmpl, inst);
	if (err) {
err_free_inst:
		crypto_lrw_free(inst);
	}
	return err;
}

static struct crypto_template crypto_tmpl = {
	.name = "lrw",
	.create = create,
	.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);
}

subsys_initcall(crypto_module_init);
module_exit(crypto_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");
MODULE_ALIAS_CRYPTO("lrw");
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/* LRW: as defined by Cyril Guyot in
	3	* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
	4	*
	5	* Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
	6	*
	7	* Based on ecb.c
	8	* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
	9	*/
	10	/* This implementation is checked against the test vectors in the above
	11	* document and by a test vector provided by Ken Buchanan at
	12	* http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
	13	*
	14	* The test vectors are included in the testing module tcrypt.[ch] */
	15
	16	#include <crypto/internal/skcipher.h>
	17	#include <crypto/scatterwalk.h>
	18	#include <linux/err.h>
	19	#include <linux/init.h>
	20	#include <linux/kernel.h>
	21	#include <linux/module.h>
	22	#include <linux/scatterlist.h>
	23	#include <linux/slab.h>
	24
	25	#include <crypto/b128ops.h>
	26	#include <crypto/gf128mul.h>
	27
	28	#define LRW_BLOCK_SIZE 16
	29
	30	struct priv {
	31	struct crypto_skcipher *child;
	32
	33	/*
	34	* optimizes multiplying a random (non incrementing, as at the
	35	* start of a new sector) value with key2, we could also have
	36	* used 4k optimization tables or no optimization at all. In the
	37	* latter case we would have to store key2 here
	38	*/
	39	struct gf128mul_64k *table;
	40
	41	/*
	42	* stores:
	43	* key2{ 0,0,...0,0,0,0,1 }, key2{ 0,0,...0,0,0,1,1 },
	44	* key2{ 0,0,...0,0,1,1,1 }, key2{ 0,0,...0,1,1,1,1 }
	45	* key2*{ 0,0,...1,1,1,1,1 }, etc
	46	* needed for optimized multiplication of incrementing values
	47	* with key2
	48	*/
	49	be128 mulinc[128];
	50	};
	51
	52	struct rctx {
	53	be128 t;
	54	struct skcipher_request subreq;
	55	};
	56
	57	static inline void setbit128_bbe(void *b, int bit)
	58	{
	59	__set_bit(bit ^ (0x80 -
	60	#ifdef __BIG_ENDIAN
	61	BITS_PER_LONG
	62	#else
	63	BITS_PER_BYTE
	64	#endif
	65	), b);
	66	}
	67
	68	static int setkey(struct crypto_skcipher parent, const u8 key,
	69	unsigned int keylen)
	70	{
	71	struct priv *ctx = crypto_skcipher_ctx(parent);
	72	struct crypto_skcipher *child = ctx->child;
	73	int err, bsize = LRW_BLOCK_SIZE;
	74	const u8 *tweak = key + keylen - bsize;
	75	be128 tmp = { 0 };
	76	int i;
	77
	78	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	79	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	80	CRYPTO_TFM_REQ_MASK);
	81	err = crypto_skcipher_setkey(child, key, keylen - bsize);
	82	if (err)
	83	return err;
	84
	85	if (ctx->table)
	86	gf128mul_free_64k(ctx->table);
	87
	88	/* initialize multiplication table for Key2 */
	89	ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
	90	if (!ctx->table)
	91	return -ENOMEM;
	92
	93	/* initialize optimization table */
	94	for (i = 0; i < 128; i++) {
	95	setbit128_bbe(&tmp, i);
	96	ctx->mulinc[i] = tmp;
	97	gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
	98	}
	99
	100	return 0;
	101	}
	102
	103	/*
	104	* Returns the number of trailing '1' bits in the words of the counter, which is
	105	* represented by 4 32-bit words, arranged from least to most significant.
	106	* At the same time, increments the counter by one.
	107	*
	108	* For example:
	109	*
	110	* u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
	111	* int i = next_index(&counter);
	112	* // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
	113	*/
	114	static int next_index(u32 *counter)
	115	{
	116	int i, res = 0;
	117
	118	for (i = 0; i < 4; i++) {
	119	if (counter[i] + 1 != 0)
	120	return res + ffz(counter[i]++);
	121
	122	counter[i] = 0;
	123	res += 32;
	124	}
	125
	126	/*
	127	* If we get here, then x == 128 and we are incrementing the counter
	128	* from all ones to all zeros. This means we must return index 127, i.e.
	129	* the one corresponding to key2*{ 1,...,1 }.
	130	*/
	131	return 127;
	132	}
	133
	134	/*
	135	* We compute the tweak masks twice (both before and after the ECB encryption or
	136	* decryption) to avoid having to allocate a temporary buffer and/or make
	137	* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
	138	* just doing the next_index() calls again.
	139	*/
	140	static int xor_tweak(struct skcipher_request *req, bool second_pass)
	141	{
	142	const int bs = LRW_BLOCK_SIZE;
	143	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	144	struct priv *ctx = crypto_skcipher_ctx(tfm);
	145	struct rctx *rctx = skcipher_request_ctx(req);
	146	be128 t = rctx->t;
	147	struct skcipher_walk w;
	148	__be32 *iv;
	149	u32 counter[4];
	150	int err;
	151
	152	if (second_pass) {
	153	req = &rctx->subreq;
	154	/* set to our TFM to enforce correct alignment: */
	155	skcipher_request_set_tfm(req, tfm);
	156	}
	157
	158	err = skcipher_walk_virt(&w, req, false);
	159	if (err)
	160	return err;
	161
	162	iv = (__be32 *)w.iv;
	163	counter[0] = be32_to_cpu(iv[3]);
	164	counter[1] = be32_to_cpu(iv[2]);
	165	counter[2] = be32_to_cpu(iv[1]);
	166	counter[3] = be32_to_cpu(iv[0]);
	167
	168	while (w.nbytes) {
	169	unsigned int avail = w.nbytes;
	170	be128 *wsrc;
	171	be128 *wdst;
	172
	173	wsrc = w.src.virt.addr;
	174	wdst = w.dst.virt.addr;
	175
	176	do {
	177	be128_xor(wdst++, &t, wsrc++);
	178
	179	/* T <- I*Key2, using the optimization
	180	* discussed in the specification */
	181	be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
	182	} while ((avail -= bs) >= bs);
	183
	184	if (second_pass && w.nbytes == w.total) {
	185	iv[0] = cpu_to_be32(counter[3]);
	186	iv[1] = cpu_to_be32(counter[2]);
	187	iv[2] = cpu_to_be32(counter[1]);
	188	iv[3] = cpu_to_be32(counter[0]);
	189	}
	190
	191	err = skcipher_walk_done(&w, avail);
	192	}
	193
	194	return err;
	195	}
	196
	197	static int xor_tweak_pre(struct skcipher_request *req)
	198	{
	199	return xor_tweak(req, false);
	200	}
	201
	202	static int xor_tweak_post(struct skcipher_request *req)
	203	{
	204	return xor_tweak(req, true);
	205	}
	206
	207	static void crypt_done(struct crypto_async_request *areq, int err)
	208	{
	209	struct skcipher_request *req = areq->data;
	210
	211	if (!err) {
	212	struct rctx *rctx = skcipher_request_ctx(req);
	213
	214	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	215	err = xor_tweak_post(req);
	216	}
	217
	218	skcipher_request_complete(req, err);
	219	}
	220
	221	static void init_crypt(struct skcipher_request *req)
	222	{
	223	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	224	struct rctx *rctx = skcipher_request_ctx(req);
	225	struct skcipher_request *subreq = &rctx->subreq;
	226
	227	skcipher_request_set_tfm(subreq, ctx->child);
	228	skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
	229	/* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
	230	skcipher_request_set_crypt(subreq, req->dst, req->dst,
	231	req->cryptlen, req->iv);
	232
	233	/* calculate first value of T */
	234	memcpy(&rctx->t, req->iv, sizeof(rctx->t));
	235
	236	/* T <- IKey2 /
	237	gf128mul_64k_bbe(&rctx->t, ctx->table);
	238	}
	239
	240	static int encrypt(struct skcipher_request *req)
	241	{
	242	struct rctx *rctx = skcipher_request_ctx(req);
	243	struct skcipher_request *subreq = &rctx->subreq;
	244
	245	init_crypt(req);
	246	return xor_tweak_pre(req) ?:
	247	crypto_skcipher_encrypt(subreq) ?:
	248	xor_tweak_post(req);
	249	}
	250
	251	static int decrypt(struct skcipher_request *req)
	252	{
	253	struct rctx *rctx = skcipher_request_ctx(req);
	254	struct skcipher_request *subreq = &rctx->subreq;
	255
	256	init_crypt(req);
	257	return xor_tweak_pre(req) ?:
	258	crypto_skcipher_decrypt(subreq) ?:
	259	xor_tweak_post(req);
	260	}
	261
	262	static int init_tfm(struct crypto_skcipher *tfm)
	263	{
	264	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	265	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
	266	struct priv *ctx = crypto_skcipher_ctx(tfm);
	267	struct crypto_skcipher *cipher;
	268
	269	cipher = crypto_spawn_skcipher(spawn);
	270	if (IS_ERR(cipher))
	271	return PTR_ERR(cipher);
	272
	273	ctx->child = cipher;
	274
	275	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
	276	sizeof(struct rctx));
	277
	278	return 0;
	279	}
	280
	281	static void exit_tfm(struct crypto_skcipher *tfm)
	282	{
	283	struct priv *ctx = crypto_skcipher_ctx(tfm);
	284
	285	if (ctx->table)
	286	gf128mul_free_64k(ctx->table);
	287	crypto_free_skcipher(ctx->child);
	288	}
	289
	290	static void crypto_lrw_free(struct skcipher_instance *inst)
	291	{
	292	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	293	kfree(inst);
	294	}
	295
	296	static int create(struct crypto_template tmpl, struct rtattr *tb)
	297	{
	298	struct crypto_skcipher_spawn *spawn;
	299	struct skcipher_instance *inst;
	300	struct skcipher_alg *alg;
	301	const char *cipher_name;
	302	char ecb_name[CRYPTO_MAX_ALG_NAME];
	303	u32 mask;
	304	int err;
	305
	306	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
	307	if (err)
	308	return err;
	309
	310	cipher_name = crypto_attr_alg_name(tb[1]);
	311	if (IS_ERR(cipher_name))
	312	return PTR_ERR(cipher_name);
	313
	314	inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
	315	if (!inst)
	316	return -ENOMEM;
	317
	318	spawn = skcipher_instance_ctx(inst);
	319
	320	err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),
	321	cipher_name, 0, mask);
	322	if (err == -ENOENT) {
	323	err = -ENAMETOOLONG;
	324	if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	325	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	326	goto err_free_inst;
	327
	328	err = crypto_grab_skcipher(spawn,
	329	skcipher_crypto_instance(inst),
	330	ecb_name, 0, mask);
	331	}
	332
	333	if (err)
	334	goto err_free_inst;
	335
	336	alg = crypto_skcipher_spawn_alg(spawn);
	337
	338	err = -EINVAL;
	339	if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
	340	goto err_free_inst;
	341
	342	if (crypto_skcipher_alg_ivsize(alg))
	343	goto err_free_inst;
	344
	345	err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
	346	&alg->base);
	347	if (err)
	348	goto err_free_inst;
	349
	350	err = -EINVAL;
	351	cipher_name = alg->base.cra_name;
	352
	353	/* Alas we screwed up the naming so we have to mangle the
	354	* cipher name.
	355	*/
	356	if (!strncmp(cipher_name, "ecb(", 4)) {
	357	unsigned len;
	358
	359	len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
	360	if (len < 2 \|\| len >= sizeof(ecb_name))
	361	goto err_free_inst;
	362
	363	if (ecb_name[len - 1] != ')')
	364	goto err_free_inst;
	365
	366	ecb_name[len - 1] = 0;
	367
	368	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
	369	"lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
	370	err = -ENAMETOOLONG;
	371	goto err_free_inst;
	372	}
	373	} else
	374	goto err_free_inst;
	375
	376	inst->alg.base.cra_priority = alg->base.cra_priority;
	377	inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
	378	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	379	(__alignof__(be128) - 1);
	380
	381	inst->alg.ivsize = LRW_BLOCK_SIZE;
	382	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
	383	LRW_BLOCK_SIZE;
	384	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
	385	LRW_BLOCK_SIZE;
	386
	387	inst->alg.base.cra_ctxsize = sizeof(struct priv);
	388
	389	inst->alg.init = init_tfm;
	390	inst->alg.exit = exit_tfm;
	391
	392	inst->alg.setkey = setkey;
	393	inst->alg.encrypt = encrypt;
	394	inst->alg.decrypt = decrypt;
	395
	396	inst->free = crypto_lrw_free;
	397
	398	err = skcipher_register_instance(tmpl, inst);
	399	if (err) {
	400	err_free_inst:
	401	crypto_lrw_free(inst);
	402	}
	403	return err;
	404	}
	405
	406	static struct crypto_template crypto_tmpl = {
	407	.name = "lrw",
	408	.create = create,
	409	.module = THIS_MODULE,
	410	};
	411
	412	static int __init crypto_module_init(void)
	413	{
	414	return crypto_register_template(&crypto_tmpl);
	415	}
	416
	417	static void __exit crypto_module_exit(void)
	418	{
	419	crypto_unregister_template(&crypto_tmpl);
	420	}
	421
	422	subsys_initcall(crypto_module_init);
	423	module_exit(crypto_module_exit);
	424
	425	MODULE_LICENSE("GPL");
	426	MODULE_DESCRIPTION("LRW block cipher mode");
	427	MODULE_ALIAS_CRYPTO("lrw");