[linux-2.6-block.git] / crypto / xts.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* XTS: as defined in IEEE1619/D16
 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
 *
 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 */
#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/xts.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>

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

struct xts_instance_ctx {
	struct crypto_skcipher_spawn spawn;
	char name[CRYPTO_MAX_ALG_NAME];
};

struct rctx {
	le128 t;
	struct scatterlist *tail;
	struct scatterlist sg[2];
	struct skcipher_request subreq;
};

static int setkey(struct crypto_skcipher *parent, const u8 *key,
		  unsigned int keylen)
{
	struct priv *ctx = crypto_skcipher_ctx(parent);
	struct crypto_skcipher *child;
	struct crypto_cipher *tweak;
	int err;

	err = xts_verify_key(parent, key, keylen);
	if (err)
		return err;

	keylen /= 2;

	/* we need two cipher instances: one to compute the initial '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 */
	tweak = ctx->tweak;
	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
				       CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
	crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
					  CRYPTO_TFM_RES_MASK);
	if (err)
		return err;

	/* data cipher, uses Key1 i.e. the first half of *key */
	child = ctx->child;
	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);
	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
					  CRYPTO_TFM_RES_MASK);

	return err;
}

/*
 * 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 gf128mul_x_ble() calls again.
 */
static int xor_tweak(struct skcipher_request *req, bool second_pass, bool enc)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
	const int bs = XTS_BLOCK_SIZE;
	struct skcipher_walk w;
	le128 t = rctx->t;
	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);

	while (w.nbytes) {
		unsigned int avail = w.nbytes;
		le128 *wsrc;
		le128 *wdst;

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

		do {
			if (unlikely(cts) &&
			    w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
				if (!enc) {
					if (second_pass)
						rctx->t = t;
					gf128mul_x_ble(&t, &t);
				}
				le128_xor(wdst, &t, wsrc);
				if (enc && second_pass)
					gf128mul_x_ble(&rctx->t, &t);
				skcipher_walk_done(&w, avail - bs);
				return 0;
			}

			le128_xor(wdst++, &t, wsrc++);
			gf128mul_x_ble(&t, &t);
		} while ((avail -= bs) >= bs);

		err = skcipher_walk_done(&w, avail);
	}

	return err;
}

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

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

static void cts_done(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->data;
	le128 b;

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

		scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
		le128_xor(&b, &rctx->t, &b);
		scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	}

	skcipher_request_complete(req, err);
}

static int cts_final(struct skcipher_request *req,
		     int (*crypt)(struct skcipher_request *req))
{
	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;
	int tail = req->cryptlen % XTS_BLOCK_SIZE;
	le128 b[2];
	int err;

	rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
				      offset - XTS_BLOCK_SIZE);

	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	memcpy(b + 1, b, tail);
	scatterwalk_map_and_copy(b, req->src, offset, tail, 0);

	le128_xor(b, &rctx->t, b);

	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);

	skcipher_request_set_tfm(subreq, ctx->child);
	skcipher_request_set_callback(subreq, req->base.flags, cts_done, req);
	skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
				   XTS_BLOCK_SIZE, NULL);

	err = crypt(subreq);
	if (err)
		return err;

	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	le128_xor(b, &rctx->t, b);
	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);

	return 0;
}

static void encrypt_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, true);

		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
			err = cts_final(req, crypto_skcipher_encrypt);
			if (err == -EINPROGRESS)
				return;
		}
	}

	skcipher_request_complete(req, err);
}

static void decrypt_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, false);

		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
			err = cts_final(req, crypto_skcipher_decrypt);
			if (err == -EINPROGRESS)
				return;
		}
	}

	skcipher_request_complete(req, err);
}

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

	if (req->cryptlen < XTS_BLOCK_SIZE)
		return -EINVAL;

	skcipher_request_set_tfm(subreq, ctx->child);
	skcipher_request_set_callback(subreq, req->base.flags, compl, req);
	skcipher_request_set_crypt(subreq, req->dst, req->dst,
				   req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);

	/* calculate first value of T */
	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);

	return 0;
}

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

	err = init_crypt(req, encrypt_done) ?:
	      xor_tweak_pre(req, true) ?:
	      crypto_skcipher_encrypt(subreq) ?:
	      xor_tweak_post(req, true);

	if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
		return err;

	return cts_final(req, crypto_skcipher_encrypt);
}

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

	err = init_crypt(req, decrypt_done) ?:
	      xor_tweak_pre(req, false) ?:
	      crypto_skcipher_decrypt(subreq) ?:
	      xor_tweak_post(req, false);

	if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
		return err;

	return cts_final(req, crypto_skcipher_decrypt);
}

static int init_tfm(struct crypto_skcipher *tfm)
{
	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	struct priv *ctx = crypto_skcipher_ctx(tfm);
	struct crypto_skcipher *child;
	struct crypto_cipher *tweak;

	child = crypto_spawn_skcipher(&ictx->spawn);
	if (IS_ERR(child))
		return PTR_ERR(child);

	ctx->child = child;

	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
	if (IS_ERR(tweak)) {
		crypto_free_skcipher(ctx->child);
		return PTR_ERR(tweak);
	}

	ctx->tweak = tweak;

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

	return 0;
}

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

	crypto_free_skcipher(ctx->child);
	crypto_free_cipher(ctx->tweak);
}

static void 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 skcipher_instance *inst;
	struct crypto_attr_type *algt;
	struct xts_instance_ctx *ctx;
	struct skcipher_alg *alg;
	const char *cipher_name;
	u32 mask;
	int err;

	algt = crypto_get_attr_type(tb);
	if (IS_ERR(algt))
		return PTR_ERR(algt);

	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
		return -EINVAL;

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

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

	ctx = skcipher_instance_ctx(inst);

	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));

	mask = crypto_requires_off(algt->type, algt->mask,
				   CRYPTO_ALG_NEED_FALLBACK |
				   CRYPTO_ALG_ASYNC);

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

		err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
	}

	if (err)
		goto err_free_inst;

	alg = crypto_skcipher_spawn_alg(&ctx->spawn);

	err = -EINVAL;
	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
		goto err_drop_spawn;

	if (crypto_skcipher_alg_ivsize(alg))
		goto err_drop_spawn;

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

	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(ctx->name, cipher_name + 4, sizeof(ctx->name));
		if (len < 2 || len >= sizeof(ctx->name))
			goto err_drop_spawn;

		if (ctx->name[len - 1] != ')')
			goto err_drop_spawn;

		ctx->name[len - 1] = 0;

		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
			     "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
			err = -ENAMETOOLONG;
			goto err_drop_spawn;
		}
	} else
		goto err_drop_spawn;

	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.base.cra_priority = alg->base.cra_priority;
	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
				       (__alignof__(u64) - 1);

	inst->alg.ivsize = XTS_BLOCK_SIZE;
	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;

	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 = free;

	err = skcipher_register_instance(tmpl, inst);
	if (err)
		goto err_drop_spawn;

out:
	return err;

err_drop_spawn:
	crypto_drop_skcipher(&ctx->spawn);
err_free_inst:
	kfree(inst);
	goto out;
}

static struct crypto_template crypto_tmpl = {
	.name = "xts",
	.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("XTS block cipher mode");
MODULE_ALIAS_CRYPTO("xts");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
f19f5111 RS	2	/* XTS: as defined in IEEE1619/D16
f19f5111 RS	3	* http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
f19f5111 RS	4	*
	5	* Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
	6	*
ddbc7361	7	* Based on ecb.c
f19f5111	8	* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
f19f5111	9	*/
f1c131b4 HX	10	#include <crypto/internal/skcipher.h>
f1c131b4 HX	11	#include <crypto/scatterwalk.h>
f19f5111 RS	12	#include <linux/err.h>
	13	#include <linux/init.h>
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
	16	#include <linux/scatterlist.h>
	17	#include <linux/slab.h>
	18
ce004556	19	#include <crypto/xts.h>
f19f5111 RS	20	#include <crypto/b128ops.h>
	21	#include <crypto/gf128mul.h>
	22
	23	struct priv {
f1c131b4	24	struct crypto_skcipher *child;
f19f5111 RS	25	struct crypto_cipher *tweak;
	26	};
	27
f1c131b4 HX	28	struct xts_instance_ctx {
	29	struct crypto_skcipher_spawn spawn;
	30	char name[CRYPTO_MAX_ALG_NAME];
	31	};
	32
	33	struct rctx {
e55318c8	34	le128 t;
8083b1bf AB	35	struct scatterlist *tail;
8083b1bf AB	36	struct scatterlist sg[2];
f1c131b4 HX	37	struct skcipher_request subreq;
	38	};
	39
	40	static int setkey(struct crypto_skcipher parent, const u8 key,
f19f5111 RS	41	unsigned int keylen)
f19f5111 RS	42	{
f1c131b4 HX	43	struct priv *ctx = crypto_skcipher_ctx(parent);
	44	struct crypto_skcipher *child;
	45	struct crypto_cipher *tweak;
f19f5111 RS	46	int err;
f19f5111 RS	47
f1c131b4	48	err = xts_verify_key(parent, key, keylen);
28856a9e SM	49	if (err)
28856a9e SM	50	return err;
f19f5111	51
f1c131b4 HX	52	keylen /= 2;
f1c131b4 HX	53
25985edc	54	/* we need two cipher instances: one to compute the initial 'tweak'
f19f5111 RS	55	* by encrypting the IV (usually the 'plain' iv) and the other
	56	* one to encrypt and decrypt the data */
	57
	58	/* tweak cipher, uses Key2 i.e. the second half of key /
f1c131b4 HX	59	tweak = ctx->tweak;
	60	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
	61	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
f19f5111	62	CRYPTO_TFM_REQ_MASK);
f1c131b4 HX	63	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
	64	crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
	65	CRYPTO_TFM_RES_MASK);
f19f5111 RS	66	if (err)
	67	return err;
	68
f1c131b4	69	/* data cipher, uses Key1 i.e. the first half of key /
f19f5111	70	child = ctx->child;
f1c131b4 HX	71	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	72	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	73	CRYPTO_TFM_REQ_MASK);
	74	err = crypto_skcipher_setkey(child, key, keylen);
	75	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
	76	CRYPTO_TFM_RES_MASK);
f19f5111	77
f1c131b4 HX	78	return err;
f1c131b4 HX	79	}
f19f5111	80
78105c7e OM	81	/*
	82	* We compute the tweak masks twice (both before and after the ECB encryption or
	83	* decryption) to avoid having to allocate a temporary buffer and/or make
	84	* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
	85	* just doing the gf128mul_x_ble() calls again.
	86	*/
8083b1bf	87	static int xor_tweak(struct skcipher_request *req, bool second_pass, bool enc)
f1c131b4 HX	88	{
f1c131b4 HX	89	struct rctx *rctx = skcipher_request_ctx(req);
78105c7e	90	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
8083b1bf	91	const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
f1c131b4 HX	92	const int bs = XTS_BLOCK_SIZE;
f1c131b4 HX	93	struct skcipher_walk w;
78105c7e	94	le128 t = rctx->t;
f1c131b4	95	int err;
f19f5111	96
78105c7e OM	97	if (second_pass) {
	98	req = &rctx->subreq;
	99	/* set to our TFM to enforce correct alignment: */
	100	skcipher_request_set_tfm(req, tfm);
f1c131b4	101	}
78105c7e	102	err = skcipher_walk_virt(&w, req, false);
f19f5111	103
f1c131b4 HX	104	while (w.nbytes) {
f1c131b4 HX	105	unsigned int avail = w.nbytes;
e55318c8 OM	106	le128 *wsrc;
e55318c8 OM	107	le128 *wdst;
f19f5111	108
f1c131b4 HX	109	wsrc = w.src.virt.addr;
f1c131b4 HX	110	wdst = w.dst.virt.addr;
f19f5111	111
f1c131b4	112	do {
8083b1bf AB	113	if (unlikely(cts) &&
	114	w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
	115	if (!enc) {
	116	if (second_pass)
	117	rctx->t = t;
	118	gf128mul_x_ble(&t, &t);
	119	}
	120	le128_xor(wdst, &t, wsrc);
	121	if (enc && second_pass)
	122	gf128mul_x_ble(&rctx->t, &t);
	123	skcipher_walk_done(&w, avail - bs);
	124	return 0;
	125	}
	126
78105c7e OM	127	le128_xor(wdst++, &t, wsrc++);
78105c7e OM	128	gf128mul_x_ble(&t, &t);
f19f5111 RS	129	} while ((avail -= bs) >= bs);
f19f5111 RS	130
f1c131b4 HX	131	err = skcipher_walk_done(&w, avail);
	132	}
	133
f19f5111 RS	134	return err;
	135	}
	136
8083b1bf AB	137	static int xor_tweak_pre(struct skcipher_request *req, bool enc)
	138	{
	139	return xor_tweak(req, false, enc);
	140	}
	141
	142	static int xor_tweak_post(struct skcipher_request *req, bool enc)
	143	{
	144	return xor_tweak(req, true, enc);
	145	}
	146
	147	static void cts_done(struct crypto_async_request *areq, int err)
f19f5111	148	{
8083b1bf AB	149	struct skcipher_request *req = areq->data;
	150	le128 b;
	151
	152	if (!err) {
	153	struct rctx *rctx = skcipher_request_ctx(req);
	154
	155	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	156	le128_xor(&b, &rctx->t, &b);
	157	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	158	}
	159
	160	skcipher_request_complete(req, err);
	161	}
	162
	163	static int cts_final(struct skcipher_request *req,
	164	int (crypt)(struct skcipher_request req))
	165	{
	166	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	167	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
	168	struct rctx *rctx = skcipher_request_ctx(req);
	169	struct skcipher_request *subreq = &rctx->subreq;
	170	int tail = req->cryptlen % XTS_BLOCK_SIZE;
	171	le128 b[2];
	172	int err;
	173
	174	rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
	175	offset - XTS_BLOCK_SIZE);
	176
	177	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	178	memcpy(b + 1, b, tail);
	179	scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
	180
	181	le128_xor(b, &rctx->t, b);
	182
	183	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
	184
	185	skcipher_request_set_tfm(subreq, ctx->child);
	186	skcipher_request_set_callback(subreq, req->base.flags, cts_done, req);
	187	skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
	188	XTS_BLOCK_SIZE, NULL);
	189
	190	err = crypt(subreq);
	191	if (err)
	192	return err;
	193
	194	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	195	le128_xor(b, &rctx->t, b);
	196	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	197
	198	return 0;
f1c131b4 HX	199	}
f1c131b4 HX	200
8083b1bf	201	static void encrypt_done(struct crypto_async_request *areq, int err)
f1c131b4	202	{
8083b1bf AB	203	struct skcipher_request *req = areq->data;
	204
	205	if (!err) {
	206	struct rctx *rctx = skcipher_request_ctx(req);
	207
	208	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	209	err = xor_tweak_post(req, true);
	210
	211	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
	212	err = cts_final(req, crypto_skcipher_encrypt);
	213	if (err == -EINPROGRESS)
	214	return;
	215	}
	216	}
	217
	218	skcipher_request_complete(req, err);
f1c131b4 HX	219	}
f1c131b4 HX	220
8083b1bf	221	static void decrypt_done(struct crypto_async_request *areq, int err)
f1c131b4 HX	222	{
f1c131b4 HX	223	struct skcipher_request *req = areq->data;
aa4a829b	224
44427c0f HX	225	if (!err) {
	226	struct rctx *rctx = skcipher_request_ctx(req);
	227
	228	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
8083b1bf AB	229	err = xor_tweak_post(req, false);
	230
	231	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
	232	err = cts_final(req, crypto_skcipher_decrypt);
	233	if (err == -EINPROGRESS)
	234	return;
	235	}
44427c0f	236	}
f1c131b4	237
f1c131b4 HX	238	skcipher_request_complete(req, err);
	239	}
	240
8083b1bf	241	static int init_crypt(struct skcipher_request *req, crypto_completion_t compl)
f1c131b4	242	{
78105c7e	243	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
f1c131b4	244	struct rctx *rctx = skcipher_request_ctx(req);
78105c7e	245	struct skcipher_request *subreq = &rctx->subreq;
f1c131b4	246
8083b1bf AB	247	if (req->cryptlen < XTS_BLOCK_SIZE)
	248	return -EINVAL;
	249
78105c7e	250	skcipher_request_set_tfm(subreq, ctx->child);
8083b1bf	251	skcipher_request_set_callback(subreq, req->base.flags, compl, req);
78105c7e	252	skcipher_request_set_crypt(subreq, req->dst, req->dst,
8083b1bf	253	req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);
f1c131b4	254
78105c7e OM	255	/* calculate first value of T */
78105c7e OM	256	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
8083b1bf AB	257
8083b1bf AB	258	return 0;
f1c131b4 HX	259	}
f1c131b4 HX	260
78105c7e	261	static int encrypt(struct skcipher_request *req)
f1c131b4	262	{
78105c7e OM	263	struct rctx *rctx = skcipher_request_ctx(req);
78105c7e OM	264	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	265	int err;
	266
	267	err = init_crypt(req, encrypt_done) ?:
	268	xor_tweak_pre(req, true) ?:
	269	crypto_skcipher_encrypt(subreq) ?:
	270	xor_tweak_post(req, true);
f1c131b4	271
8083b1bf AB	272	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	273	return err;
	274
	275	return cts_final(req, crypto_skcipher_encrypt);
f1c131b4 HX	276	}
	277
	278	static int decrypt(struct skcipher_request *req)
	279	{
78105c7e OM	280	struct rctx *rctx = skcipher_request_ctx(req);
78105c7e OM	281	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	282	int err;
	283
	284	err = init_crypt(req, decrypt_done) ?:
	285	xor_tweak_pre(req, false) ?:
	286	crypto_skcipher_decrypt(subreq) ?:
	287	xor_tweak_post(req, false);
	288
	289	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	290	return err;
78105c7e	291
8083b1bf	292	return cts_final(req, crypto_skcipher_decrypt);
f19f5111 RS	293	}
f19f5111 RS	294
f1c131b4	295	static int init_tfm(struct crypto_skcipher *tfm)
f19f5111	296	{
f1c131b4 HX	297	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	298	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	299	struct priv *ctx = crypto_skcipher_ctx(tfm);
	300	struct crypto_skcipher *child;
	301	struct crypto_cipher *tweak;
f19f5111	302
f1c131b4 HX	303	child = crypto_spawn_skcipher(&ictx->spawn);
	304	if (IS_ERR(child))
	305	return PTR_ERR(child);
f19f5111	306
f1c131b4	307	ctx->child = child;
f19f5111	308
f1c131b4 HX	309	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
	310	if (IS_ERR(tweak)) {
	311	crypto_free_skcipher(ctx->child);
	312	return PTR_ERR(tweak);
f19f5111 RS	313	}
f19f5111 RS	314
f1c131b4 HX	315	ctx->tweak = tweak;
	316
	317	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
	318	sizeof(struct rctx));
f19f5111 RS	319
	320	return 0;
	321	}
	322
f1c131b4	323	static void exit_tfm(struct crypto_skcipher *tfm)
f19f5111	324	{
f1c131b4 HX	325	struct priv *ctx = crypto_skcipher_ctx(tfm);
	326
	327	crypto_free_skcipher(ctx->child);
f19f5111 RS	328	crypto_free_cipher(ctx->tweak);
	329	}
	330
f1c131b4 HX	331	static void free(struct skcipher_instance *inst)
	332	{
	333	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	334	kfree(inst);
	335	}
	336
	337	static int create(struct crypto_template tmpl, struct rtattr *tb)
f19f5111	338	{
f1c131b4 HX	339	struct skcipher_instance *inst;
	340	struct crypto_attr_type *algt;
	341	struct xts_instance_ctx *ctx;
	342	struct skcipher_alg *alg;
	343	const char *cipher_name;
89027579	344	u32 mask;
f19f5111 RS	345	int err;
f19f5111 RS	346
f1c131b4 HX	347	algt = crypto_get_attr_type(tb);
	348	if (IS_ERR(algt))
	349	return PTR_ERR(algt);
	350
	351	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
	352	return -EINVAL;
	353
	354	cipher_name = crypto_attr_alg_name(tb[1]);
	355	if (IS_ERR(cipher_name))
	356	return PTR_ERR(cipher_name);
	357
	358	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	359	if (!inst)
	360	return -ENOMEM;
	361
	362	ctx = skcipher_instance_ctx(inst);
	363
	364	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
89027579 HX	365
	366	mask = crypto_requires_off(algt->type, algt->mask,
	367	CRYPTO_ALG_NEED_FALLBACK \|
	368	CRYPTO_ALG_ASYNC);
	369
	370	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
f1c131b4 HX	371	if (err == -ENOENT) {
	372	err = -ENAMETOOLONG;
	373	if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	374	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	375	goto err_free_inst;
	376
89027579	377	err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
f1c131b4 HX	378	}
f1c131b4 HX	379
f19f5111	380	if (err)
f1c131b4	381	goto err_free_inst;
f19f5111	382
f1c131b4	383	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
f19f5111	384
f1c131b4 HX	385	err = -EINVAL;
	386	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
	387	goto err_drop_spawn;
f19f5111	388
f1c131b4 HX	389	if (crypto_skcipher_alg_ivsize(alg))
f1c131b4 HX	390	goto err_drop_spawn;
f19f5111	391
f1c131b4 HX	392	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
	393	&alg->base);
	394	if (err)
	395	goto err_drop_spawn;
f19f5111	396
f1c131b4 HX	397	err = -EINVAL;
f1c131b4 HX	398	cipher_name = alg->base.cra_name;
f19f5111	399
f1c131b4 HX	400	/* Alas we screwed up the naming so we have to mangle the
	401	* cipher name.
	402	*/
	403	if (!strncmp(cipher_name, "ecb(", 4)) {
	404	unsigned len;
f19f5111	405
f1c131b4 HX	406	len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
	407	if (len < 2 \|\| len >= sizeof(ctx->name))
	408	goto err_drop_spawn;
f19f5111	409
f1c131b4 HX	410	if (ctx->name[len - 1] != ')')
f1c131b4 HX	411	goto err_drop_spawn;
f19f5111	412
f1c131b4	413	ctx->name[len - 1] = 0;
f19f5111	414
f1c131b4	415	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
5125e4e8 CJ	416	"xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
	417	err = -ENAMETOOLONG;
	418	goto err_drop_spawn;
	419	}
f1c131b4 HX	420	} else
f1c131b4 HX	421	goto err_drop_spawn;
f19f5111	422
f1c131b4 HX	423	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	424	inst->alg.base.cra_priority = alg->base.cra_priority;
	425	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	426	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	427	(__alignof__(u64) - 1);
	428
	429	inst->alg.ivsize = XTS_BLOCK_SIZE;
	430	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	431	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
	432
	433	inst->alg.base.cra_ctxsize = sizeof(struct priv);
	434
	435	inst->alg.init = init_tfm;
	436	inst->alg.exit = exit_tfm;
	437
	438	inst->alg.setkey = setkey;
	439	inst->alg.encrypt = encrypt;
	440	inst->alg.decrypt = decrypt;
	441
	442	inst->free = free;
	443
	444	err = skcipher_register_instance(tmpl, inst);
	445	if (err)
	446	goto err_drop_spawn;
	447
	448	out:
	449	return err;
	450
	451	err_drop_spawn:
	452	crypto_drop_skcipher(&ctx->spawn);
	453	err_free_inst:
f19f5111	454	kfree(inst);
f1c131b4	455	goto out;
f19f5111 RS	456	}
	457
	458	static struct crypto_template crypto_tmpl = {
	459	.name = "xts",
f1c131b4	460	.create = create,
f19f5111 RS	461	.module = THIS_MODULE,
	462	};
	463
	464	static int __init crypto_module_init(void)
	465	{
	466	return crypto_register_template(&crypto_tmpl);
	467	}
	468
	469	static void __exit crypto_module_exit(void)
	470	{
	471	crypto_unregister_template(&crypto_tmpl);
	472	}
	473
c4741b23	474	subsys_initcall(crypto_module_init);
f19f5111 RS	475	module_exit(crypto_module_exit);
	476
	477	MODULE_LICENSE("GPL");
	478	MODULE_DESCRIPTION("XTS block cipher mode");
4943ba16	479	MODULE_ALIAS_CRYPTO("xts");