[linux-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/cipher.h>
#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 xts_tfm_ctx {
	struct crypto_skcipher *child;
	struct crypto_cipher *tweak;
};

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

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

static int xts_setkey(struct crypto_skcipher *parent, const u8 *key,
		      unsigned int keylen)
{
	struct xts_tfm_ctx *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);
	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);
	return crypto_skcipher_setkey(child, key, keylen);
}

/*
 * 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 xts_xor_tweak(struct skcipher_request *req, bool second_pass,
			 bool enc)
{
	struct xts_request_ctx *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 xts_xor_tweak_pre(struct skcipher_request *req, bool enc)
{
	return xts_xor_tweak(req, false, enc);
}

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

static void xts_cts_done(void *data, int err)
{
	struct skcipher_request *req = data;
	le128 b;

	if (!err) {
		struct xts_request_ctx *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 xts_cts_final(struct skcipher_request *req,
			 int (*crypt)(struct skcipher_request *req))
{
	const struct xts_tfm_ctx *ctx =
		crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
	struct xts_request_ctx *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);
	b[1] = b[0];
	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, xts_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 xts_encrypt_done(void *data, int err)
{
	struct skcipher_request *req = data;

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

		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
		err = xts_xor_tweak_post(req, true);

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

	skcipher_request_complete(req, err);
}

static void xts_decrypt_done(void *data, int err)
{
	struct skcipher_request *req = data;

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

		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
		err = xts_xor_tweak_post(req, false);

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

	skcipher_request_complete(req, err);
}

static int xts_init_crypt(struct skcipher_request *req,
			  crypto_completion_t compl)
{
	const struct xts_tfm_ctx *ctx =
		crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	struct xts_request_ctx *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 xts_encrypt(struct skcipher_request *req)
{
	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;
	int err;

	err = xts_init_crypt(req, xts_encrypt_done) ?:
	      xts_xor_tweak_pre(req, true) ?:
	      crypto_skcipher_encrypt(subreq) ?:
	      xts_xor_tweak_post(req, true);

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

	return xts_cts_final(req, crypto_skcipher_encrypt);
}

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

	err = xts_init_crypt(req, xts_decrypt_done) ?:
	      xts_xor_tweak_pre(req, false) ?:
	      crypto_skcipher_decrypt(subreq) ?:
	      xts_xor_tweak_post(req, false);

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

	return xts_cts_final(req, crypto_skcipher_decrypt);
}

static int xts_init_tfm(struct crypto_skcipher *tfm)
{
	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	struct xts_tfm_ctx *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 xts_request_ctx));

	return 0;
}

static void xts_exit_tfm(struct crypto_skcipher *tfm)
{
	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);

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

static void xts_free_instance(struct skcipher_instance *inst)
{
	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);

	crypto_drop_skcipher(&ictx->spawn);
	kfree(inst);
}

static int xts_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct skcipher_instance *inst;
	struct xts_instance_ctx *ctx;
	struct skcipher_alg *alg;
	const char *cipher_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(*ctx), GFP_KERNEL);
	if (!inst)
		return -ENOMEM;

	ctx = skcipher_instance_ctx(inst);

	err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst),
				   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,
					   skcipher_crypto_instance(inst),
					   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_free_inst;

	if (crypto_skcipher_alg_ivsize(alg))
		goto err_free_inst;

	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
				  &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(ctx->name, cipher_name + 4, sizeof(ctx->name));
		if (len < 2 || len >= sizeof(ctx->name))
			goto err_free_inst;

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

		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_free_inst;
		}
	} else
		goto err_free_inst;

	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 xts_tfm_ctx);

	inst->alg.init = xts_init_tfm;
	inst->alg.exit = xts_exit_tfm;

	inst->alg.setkey = xts_setkey;
	inst->alg.encrypt = xts_encrypt;
	inst->alg.decrypt = xts_decrypt;

	inst->free = xts_free_instance;

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

static struct crypto_template xts_tmpl = {
	.name = "xts",
	.create = xts_create,
	.module = THIS_MODULE,
};

static int __init xts_module_init(void)
{
	return crypto_register_template(&xts_tmpl);
}

static void __exit xts_module_exit(void)
{
	crypto_unregister_template(&xts_tmpl);
}

subsys_initcall(xts_module_init);
module_exit(xts_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XTS block cipher mode");
MODULE_ALIAS_CRYPTO("xts");
MODULE_IMPORT_NS(CRYPTO_INTERNAL);
MODULE_SOFTDEP("pre: ecb");
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	*/
0eb76ba2	10	#include <crypto/internal/cipher.h>
f1c131b4 HX	11	#include <crypto/internal/skcipher.h>
f1c131b4 HX	12	#include <crypto/scatterwalk.h>
f19f5111 RS	13	#include <linux/err.h>
	14	#include <linux/init.h>
	15	#include <linux/kernel.h>
	16	#include <linux/module.h>
	17	#include <linux/scatterlist.h>
	18	#include <linux/slab.h>
	19
ce004556	20	#include <crypto/xts.h>
f19f5111 RS	21	#include <crypto/b128ops.h>
	22	#include <crypto/gf128mul.h>
	23
a874f591	24	struct xts_tfm_ctx {
f1c131b4	25	struct crypto_skcipher *child;
f19f5111 RS	26	struct crypto_cipher *tweak;
	27	};
	28
f1c131b4 HX	29	struct xts_instance_ctx {
	30	struct crypto_skcipher_spawn spawn;
	31	char name[CRYPTO_MAX_ALG_NAME];
	32	};
	33
a874f591	34	struct xts_request_ctx {
e55318c8	35	le128 t;
8083b1bf AB	36	struct scatterlist *tail;
8083b1bf AB	37	struct scatterlist sg[2];
f1c131b4 HX	38	struct skcipher_request subreq;
	39	};
	40
a874f591 EB	41	static int xts_setkey(struct crypto_skcipher parent, const u8 key,
a874f591 EB	42	unsigned int keylen)
f19f5111	43	{
a874f591	44	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(parent);
f1c131b4 HX	45	struct crypto_skcipher *child;
f1c131b4 HX	46	struct crypto_cipher *tweak;
f19f5111 RS	47	int err;
f19f5111 RS	48
f1c131b4	49	err = xts_verify_key(parent, key, keylen);
28856a9e SM	50	if (err)
28856a9e SM	51	return err;
f19f5111	52
f1c131b4 HX	53	keylen /= 2;
f1c131b4 HX	54
25985edc	55	/* we need two cipher instances: one to compute the initial 'tweak'
f19f5111 RS	56	* by encrypting the IV (usually the 'plain' iv) and the other
	57	* one to encrypt and decrypt the data */
	58
	59	/* tweak cipher, uses Key2 i.e. the second half of key /
f1c131b4 HX	60	tweak = ctx->tweak;
	61	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
	62	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
f19f5111	63	CRYPTO_TFM_REQ_MASK);
f1c131b4	64	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
f19f5111 RS	65	if (err)
	66	return err;
	67
f1c131b4	68	/* data cipher, uses Key1 i.e. the first half of key /
f19f5111	69	child = ctx->child;
f1c131b4 HX	70	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	71	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	72	CRYPTO_TFM_REQ_MASK);
af5034e8	73	return crypto_skcipher_setkey(child, key, keylen);
f1c131b4	74	}
f19f5111	75
78105c7e OM	76	/*
	77	* We compute the tweak masks twice (both before and after the ECB encryption or
	78	* decryption) to avoid having to allocate a temporary buffer and/or make
	79	* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
	80	* just doing the gf128mul_x_ble() calls again.
	81	*/
a874f591 EB	82	static int xts_xor_tweak(struct skcipher_request *req, bool second_pass,
a874f591 EB	83	bool enc)
f1c131b4	84	{
a874f591	85	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	86	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
8083b1bf	87	const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
f1c131b4 HX	88	const int bs = XTS_BLOCK_SIZE;
f1c131b4 HX	89	struct skcipher_walk w;
78105c7e	90	le128 t = rctx->t;
f1c131b4	91	int err;
f19f5111	92
78105c7e OM	93	if (second_pass) {
	94	req = &rctx->subreq;
	95	/* set to our TFM to enforce correct alignment: */
	96	skcipher_request_set_tfm(req, tfm);
f1c131b4	97	}
78105c7e	98	err = skcipher_walk_virt(&w, req, false);
f19f5111	99
f1c131b4 HX	100	while (w.nbytes) {
f1c131b4 HX	101	unsigned int avail = w.nbytes;
e55318c8 OM	102	le128 *wsrc;
e55318c8 OM	103	le128 *wdst;
f19f5111	104
f1c131b4 HX	105	wsrc = w.src.virt.addr;
f1c131b4 HX	106	wdst = w.dst.virt.addr;
f19f5111	107
f1c131b4	108	do {
8083b1bf AB	109	if (unlikely(cts) &&
	110	w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
	111	if (!enc) {
	112	if (second_pass)
	113	rctx->t = t;
	114	gf128mul_x_ble(&t, &t);
	115	}
	116	le128_xor(wdst, &t, wsrc);
	117	if (enc && second_pass)
	118	gf128mul_x_ble(&rctx->t, &t);
	119	skcipher_walk_done(&w, avail - bs);
	120	return 0;
	121	}
	122
78105c7e OM	123	le128_xor(wdst++, &t, wsrc++);
78105c7e OM	124	gf128mul_x_ble(&t, &t);
f19f5111 RS	125	} while ((avail -= bs) >= bs);
f19f5111 RS	126
f1c131b4 HX	127	err = skcipher_walk_done(&w, avail);
	128	}
	129
f19f5111 RS	130	return err;
	131	}
	132
a874f591	133	static int xts_xor_tweak_pre(struct skcipher_request *req, bool enc)
8083b1bf	134	{
a874f591	135	return xts_xor_tweak(req, false, enc);
8083b1bf AB	136	}
8083b1bf AB	137
a874f591	138	static int xts_xor_tweak_post(struct skcipher_request *req, bool enc)
8083b1bf	139	{
a874f591	140	return xts_xor_tweak(req, true, enc);
8083b1bf AB	141	}
8083b1bf AB	142
255e48eb	143	static void xts_cts_done(void *data, int err)
f19f5111	144	{
255e48eb	145	struct skcipher_request *req = data;
8083b1bf AB	146	le128 b;
	147
	148	if (!err) {
a874f591	149	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf AB	150
	151	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	152	le128_xor(&b, &rctx->t, &b);
	153	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	154	}
	155
	156	skcipher_request_complete(req, err);
	157	}
	158
a874f591 EB	159	static int xts_cts_final(struct skcipher_request *req,
a874f591 EB	160	int (crypt)(struct skcipher_request req))
8083b1bf	161	{
a874f591 EB	162	const struct xts_tfm_ctx *ctx =
a874f591 EB	163	crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
8083b1bf	164	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
a874f591	165	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf AB	166	struct skcipher_request *subreq = &rctx->subreq;
	167	int tail = req->cryptlen % XTS_BLOCK_SIZE;
	168	le128 b[2];
	169	int err;
	170
	171	rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
	172	offset - XTS_BLOCK_SIZE);
	173
	174	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
958ea4e0	175	b[1] = b[0];
8083b1bf AB	176	scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
	177
	178	le128_xor(b, &rctx->t, b);
	179
	180	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
	181
	182	skcipher_request_set_tfm(subreq, ctx->child);
a874f591 EB	183	skcipher_request_set_callback(subreq, req->base.flags, xts_cts_done,
a874f591 EB	184	req);
8083b1bf AB	185	skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
	186	XTS_BLOCK_SIZE, NULL);
	187
	188	err = crypt(subreq);
	189	if (err)
	190	return err;
	191
	192	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	193	le128_xor(b, &rctx->t, b);
	194	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	195
	196	return 0;
f1c131b4 HX	197	}
f1c131b4 HX	198
255e48eb	199	static void xts_encrypt_done(void *data, int err)
f1c131b4	200	{
255e48eb	201	struct skcipher_request *req = data;
8083b1bf AB	202
8083b1bf AB	203	if (!err) {
a874f591	204	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf	205
51c08251	206	rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
a874f591	207	err = xts_xor_tweak_post(req, true);
8083b1bf AB	208
8083b1bf AB	209	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
a874f591	210	err = xts_cts_final(req, crypto_skcipher_encrypt);
51c08251	211	if (err == -EINPROGRESS \|\| err == -EBUSY)
8083b1bf AB	212	return;
	213	}
	214	}
	215
	216	skcipher_request_complete(req, err);
f1c131b4 HX	217	}
f1c131b4 HX	218
255e48eb	219	static void xts_decrypt_done(void *data, int err)
f1c131b4	220	{
255e48eb	221	struct skcipher_request *req = data;
aa4a829b	222
44427c0f	223	if (!err) {
a874f591	224	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
44427c0f	225
51c08251	226	rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
a874f591	227	err = xts_xor_tweak_post(req, false);
8083b1bf AB	228
8083b1bf AB	229	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
a874f591	230	err = xts_cts_final(req, crypto_skcipher_decrypt);
51c08251	231	if (err == -EINPROGRESS \|\| err == -EBUSY)
8083b1bf AB	232	return;
8083b1bf AB	233	}
44427c0f	234	}
f1c131b4	235
f1c131b4 HX	236	skcipher_request_complete(req, err);
	237	}
	238
a874f591 EB	239	static int xts_init_crypt(struct skcipher_request *req,
a874f591 EB	240	crypto_completion_t compl)
f1c131b4	241	{
a874f591 EB	242	const struct xts_tfm_ctx *ctx =
	243	crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	244	struct xts_request_ctx *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
a874f591	261	static int xts_encrypt(struct skcipher_request *req)
f1c131b4	262	{
a874f591	263	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	264	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	265	int err;
8083b1bf AB	266
a874f591 EB	267	err = xts_init_crypt(req, xts_encrypt_done) ?:
a874f591 EB	268	xts_xor_tweak_pre(req, true) ?:
8083b1bf	269	crypto_skcipher_encrypt(subreq) ?:
a874f591	270	xts_xor_tweak_post(req, true);
f1c131b4	271
8083b1bf AB	272	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	273	return err;
	274
a874f591	275	return xts_cts_final(req, crypto_skcipher_encrypt);
f1c131b4 HX	276	}
f1c131b4 HX	277
a874f591	278	static int xts_decrypt(struct skcipher_request *req)
f1c131b4	279	{
a874f591	280	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	281	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	282	int err;
8083b1bf AB	283
a874f591 EB	284	err = xts_init_crypt(req, xts_decrypt_done) ?:
a874f591 EB	285	xts_xor_tweak_pre(req, false) ?:
8083b1bf	286	crypto_skcipher_decrypt(subreq) ?:
a874f591	287	xts_xor_tweak_post(req, false);
8083b1bf AB	288
	289	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	290	return err;
78105c7e	291
a874f591	292	return xts_cts_final(req, crypto_skcipher_decrypt);
f19f5111 RS	293	}
f19f5111 RS	294
a874f591	295	static int xts_init_tfm(struct crypto_skcipher *tfm)
f19f5111	296	{
f1c131b4 HX	297	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
f1c131b4 HX	298	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
a874f591	299	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
f1c131b4 HX	300	struct crypto_skcipher *child;
f1c131b4 HX	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) +
a874f591	318	sizeof(struct xts_request_ctx));
f19f5111 RS	319
	320	return 0;
	321	}
	322
a874f591	323	static void xts_exit_tfm(struct crypto_skcipher *tfm)
f19f5111	324	{
a874f591	325	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
f1c131b4 HX	326
f1c131b4 HX	327	crypto_free_skcipher(ctx->child);
f19f5111 RS	328	crypto_free_cipher(ctx->tweak);
	329	}
	330
a874f591	331	static void xts_free_instance(struct skcipher_instance *inst)
f1c131b4	332	{
a874f591 EB	333	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	334
	335	crypto_drop_skcipher(&ictx->spawn);
f1c131b4 HX	336	kfree(inst);
	337	}
	338
a874f591	339	static int xts_create(struct crypto_template tmpl, struct rtattr *tb)
f19f5111	340	{
f1c131b4	341	struct skcipher_instance *inst;
f1c131b4 HX	342	struct xts_instance_ctx *ctx;
	343	struct skcipher_alg *alg;
	344	const char *cipher_name;
89027579	345	u32 mask;
f19f5111 RS	346	int err;
f19f5111 RS	347
7bcb2c99 EB	348	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
	349	if (err)
	350	return err;
f1c131b4 HX	351
	352	cipher_name = crypto_attr_alg_name(tb[1]);
	353	if (IS_ERR(cipher_name))
	354	return PTR_ERR(cipher_name);
	355
	356	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	357	if (!inst)
	358	return -ENOMEM;
	359
	360	ctx = skcipher_instance_ctx(inst);
	361
b9f76ddd EB	362	err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst),
b9f76ddd EB	363	cipher_name, 0, mask);
f1c131b4 HX	364	if (err == -ENOENT) {
	365	err = -ENAMETOOLONG;
	366	if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	367	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	368	goto err_free_inst;
	369
b9f76ddd EB	370	err = crypto_grab_skcipher(&ctx->spawn,
	371	skcipher_crypto_instance(inst),
	372	ctx->name, 0, mask);
f1c131b4 HX	373	}
f1c131b4 HX	374
f19f5111	375	if (err)
f1c131b4	376	goto err_free_inst;
f19f5111	377
f1c131b4	378	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
f19f5111	379
f1c131b4 HX	380	err = -EINVAL;
f1c131b4 HX	381	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
732e5409	382	goto err_free_inst;
f19f5111	383
f1c131b4	384	if (crypto_skcipher_alg_ivsize(alg))
732e5409	385	goto err_free_inst;
f19f5111	386
f1c131b4 HX	387	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
	388	&alg->base);
	389	if (err)
732e5409	390	goto err_free_inst;
f19f5111	391
f1c131b4 HX	392	err = -EINVAL;
f1c131b4 HX	393	cipher_name = alg->base.cra_name;
f19f5111	394
f1c131b4 HX	395	/* Alas we screwed up the naming so we have to mangle the
	396	* cipher name.
	397	*/
	398	if (!strncmp(cipher_name, "ecb(", 4)) {
	399	unsigned len;
f19f5111	400
f1c131b4 HX	401	len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
f1c131b4 HX	402	if (len < 2 \|\| len >= sizeof(ctx->name))
732e5409	403	goto err_free_inst;
f19f5111	404
f1c131b4	405	if (ctx->name[len - 1] != ')')
732e5409	406	goto err_free_inst;
f19f5111	407
f1c131b4	408	ctx->name[len - 1] = 0;
f19f5111	409
f1c131b4	410	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
5125e4e8 CJ	411	"xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
5125e4e8 CJ	412	err = -ENAMETOOLONG;
732e5409	413	goto err_free_inst;
5125e4e8	414	}
f1c131b4	415	} else
732e5409	416	goto err_free_inst;
f19f5111	417
f1c131b4 HX	418	inst->alg.base.cra_priority = alg->base.cra_priority;
	419	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	420	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	421	(__alignof__(u64) - 1);
	422
	423	inst->alg.ivsize = XTS_BLOCK_SIZE;
	424	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	425	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
	426
a874f591	427	inst->alg.base.cra_ctxsize = sizeof(struct xts_tfm_ctx);
f1c131b4	428
a874f591 EB	429	inst->alg.init = xts_init_tfm;
a874f591 EB	430	inst->alg.exit = xts_exit_tfm;
f1c131b4	431
a874f591 EB	432	inst->alg.setkey = xts_setkey;
	433	inst->alg.encrypt = xts_encrypt;
	434	inst->alg.decrypt = xts_decrypt;
f1c131b4	435
a874f591	436	inst->free = xts_free_instance;
f1c131b4 HX	437
f1c131b4 HX	438	err = skcipher_register_instance(tmpl, inst);
732e5409	439	if (err) {
f1c131b4	440	err_free_inst:
a874f591	441	xts_free_instance(inst);
732e5409 EB	442	}
732e5409 EB	443	return err;
f19f5111 RS	444	}
f19f5111 RS	445
a874f591	446	static struct crypto_template xts_tmpl = {
f19f5111	447	.name = "xts",
a874f591	448	.create = xts_create,
f19f5111 RS	449	.module = THIS_MODULE,
	450	};
	451
a874f591	452	static int __init xts_module_init(void)
f19f5111	453	{
a874f591	454	return crypto_register_template(&xts_tmpl);
f19f5111 RS	455	}
f19f5111 RS	456
a874f591	457	static void __exit xts_module_exit(void)
f19f5111	458	{
a874f591	459	crypto_unregister_template(&xts_tmpl);
f19f5111 RS	460	}
f19f5111 RS	461
a874f591 EB	462	subsys_initcall(xts_module_init);
a874f591 EB	463	module_exit(xts_module_exit);
f19f5111 RS	464
	465	MODULE_LICENSE("GPL");
	466	MODULE_DESCRIPTION("XTS block cipher mode");
4943ba16	467	MODULE_ALIAS_CRYPTO("xts");
0eb76ba2	468	MODULE_IMPORT_NS(CRYPTO_INTERNAL);
dfe085d8	469	MODULE_SOFTDEP("pre: ecb");