[linux.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 <[email protected]>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <[email protected]>
 */
#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(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->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(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->data;

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

		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
		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)
				return;
		}
	}

	skcipher_request_complete(req, err);
}

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

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

		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
		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)
				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");
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 <[email protected]>
	6	*
ddbc7361	7	* Based on ecb.c
f19f5111	8	* Copyright (c) 2006 Herbert Xu <[email protected]>
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
a874f591	23	struct xts_tfm_ctx {
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
a874f591	33	struct xts_request_ctx {
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
a874f591 EB	40	static int xts_setkey(struct crypto_skcipher parent, const u8 key,
a874f591 EB	41	unsigned int keylen)
f19f5111	42	{
a874f591	43	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(parent);
f1c131b4 HX	44	struct crypto_skcipher *child;
f1c131b4 HX	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	63	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
f19f5111 RS	64	if (err)
	65	return err;
	66
f1c131b4	67	/* data cipher, uses Key1 i.e. the first half of key /
f19f5111	68	child = ctx->child;
f1c131b4 HX	69	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	70	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	71	CRYPTO_TFM_REQ_MASK);
af5034e8	72	return crypto_skcipher_setkey(child, key, keylen);
f1c131b4	73	}
f19f5111	74
78105c7e OM	75	/*
	76	* We compute the tweak masks twice (both before and after the ECB encryption or
	77	* decryption) to avoid having to allocate a temporary buffer and/or make
	78	* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
	79	* just doing the gf128mul_x_ble() calls again.
	80	*/
a874f591 EB	81	static int xts_xor_tweak(struct skcipher_request *req, bool second_pass,
a874f591 EB	82	bool enc)
f1c131b4	83	{
a874f591	84	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	85	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
8083b1bf	86	const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
f1c131b4 HX	87	const int bs = XTS_BLOCK_SIZE;
f1c131b4 HX	88	struct skcipher_walk w;
78105c7e	89	le128 t = rctx->t;
f1c131b4	90	int err;
f19f5111	91
78105c7e OM	92	if (second_pass) {
	93	req = &rctx->subreq;
	94	/* set to our TFM to enforce correct alignment: */
	95	skcipher_request_set_tfm(req, tfm);
f1c131b4	96	}
78105c7e	97	err = skcipher_walk_virt(&w, req, false);
f19f5111	98
f1c131b4 HX	99	while (w.nbytes) {
f1c131b4 HX	100	unsigned int avail = w.nbytes;
e55318c8 OM	101	le128 *wsrc;
e55318c8 OM	102	le128 *wdst;
f19f5111	103
f1c131b4 HX	104	wsrc = w.src.virt.addr;
f1c131b4 HX	105	wdst = w.dst.virt.addr;
f19f5111	106
f1c131b4	107	do {
8083b1bf AB	108	if (unlikely(cts) &&
	109	w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
	110	if (!enc) {
	111	if (second_pass)
	112	rctx->t = t;
	113	gf128mul_x_ble(&t, &t);
	114	}
	115	le128_xor(wdst, &t, wsrc);
	116	if (enc && second_pass)
	117	gf128mul_x_ble(&rctx->t, &t);
	118	skcipher_walk_done(&w, avail - bs);
	119	return 0;
	120	}
	121
78105c7e OM	122	le128_xor(wdst++, &t, wsrc++);
78105c7e OM	123	gf128mul_x_ble(&t, &t);
f19f5111 RS	124	} while ((avail -= bs) >= bs);
f19f5111 RS	125
f1c131b4 HX	126	err = skcipher_walk_done(&w, avail);
	127	}
	128
f19f5111 RS	129	return err;
	130	}
	131
a874f591	132	static int xts_xor_tweak_pre(struct skcipher_request *req, bool enc)
8083b1bf	133	{
a874f591	134	return xts_xor_tweak(req, false, enc);
8083b1bf AB	135	}
8083b1bf AB	136
a874f591	137	static int xts_xor_tweak_post(struct skcipher_request *req, bool enc)
8083b1bf	138	{
a874f591	139	return xts_xor_tweak(req, true, enc);
8083b1bf AB	140	}
8083b1bf AB	141
a874f591	142	static void xts_cts_done(struct crypto_async_request *areq, int err)
f19f5111	143	{
8083b1bf AB	144	struct skcipher_request *req = areq->data;
	145	le128 b;
	146
	147	if (!err) {
a874f591	148	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf AB	149
	150	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	151	le128_xor(&b, &rctx->t, &b);
	152	scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	153	}
	154
	155	skcipher_request_complete(req, err);
	156	}
	157
a874f591 EB	158	static int xts_cts_final(struct skcipher_request *req,
a874f591 EB	159	int (crypt)(struct skcipher_request req))
8083b1bf	160	{
a874f591 EB	161	const struct xts_tfm_ctx *ctx =
a874f591 EB	162	crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
8083b1bf	163	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
a874f591	164	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf AB	165	struct skcipher_request *subreq = &rctx->subreq;
	166	int tail = req->cryptlen % XTS_BLOCK_SIZE;
	167	le128 b[2];
	168	int err;
	169
	170	rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
	171	offset - XTS_BLOCK_SIZE);
	172
	173	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
958ea4e0	174	b[1] = b[0];
8083b1bf AB	175	scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
	176
	177	le128_xor(b, &rctx->t, b);
	178
	179	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
	180
	181	skcipher_request_set_tfm(subreq, ctx->child);
a874f591 EB	182	skcipher_request_set_callback(subreq, req->base.flags, xts_cts_done,
a874f591 EB	183	req);
8083b1bf AB	184	skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
	185	XTS_BLOCK_SIZE, NULL);
	186
	187	err = crypt(subreq);
	188	if (err)
	189	return err;
	190
	191	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
	192	le128_xor(b, &rctx->t, b);
	193	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
	194
	195	return 0;
f1c131b4 HX	196	}
f1c131b4 HX	197
a874f591	198	static void xts_encrypt_done(struct crypto_async_request *areq, int err)
f1c131b4	199	{
8083b1bf AB	200	struct skcipher_request *req = areq->data;
	201
	202	if (!err) {
a874f591	203	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
8083b1bf AB	204
8083b1bf AB	205	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
a874f591	206	err = xts_xor_tweak_post(req, true);
8083b1bf AB	207
8083b1bf AB	208	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
a874f591	209	err = xts_cts_final(req, crypto_skcipher_encrypt);
8083b1bf AB	210	if (err == -EINPROGRESS)
	211	return;
	212	}
	213	}
	214
	215	skcipher_request_complete(req, err);
f1c131b4 HX	216	}
f1c131b4 HX	217
a874f591	218	static void xts_decrypt_done(struct crypto_async_request *areq, int err)
f1c131b4 HX	219	{
f1c131b4 HX	220	struct skcipher_request *req = areq->data;
aa4a829b	221
44427c0f	222	if (!err) {
a874f591	223	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
44427c0f HX	224
44427c0f HX	225	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
a874f591	226	err = xts_xor_tweak_post(req, false);
8083b1bf AB	227
8083b1bf AB	228	if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
a874f591	229	err = xts_cts_final(req, crypto_skcipher_decrypt);
8083b1bf AB	230	if (err == -EINPROGRESS)
	231	return;
	232	}
44427c0f	233	}
f1c131b4	234
f1c131b4 HX	235	skcipher_request_complete(req, err);
	236	}
	237
a874f591 EB	238	static int xts_init_crypt(struct skcipher_request *req,
a874f591 EB	239	crypto_completion_t compl)
f1c131b4	240	{
a874f591 EB	241	const struct xts_tfm_ctx *ctx =
	242	crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	243	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	244	struct skcipher_request *subreq = &rctx->subreq;
f1c131b4	245
8083b1bf AB	246	if (req->cryptlen < XTS_BLOCK_SIZE)
	247	return -EINVAL;
	248
78105c7e	249	skcipher_request_set_tfm(subreq, ctx->child);
8083b1bf	250	skcipher_request_set_callback(subreq, req->base.flags, compl, req);
78105c7e	251	skcipher_request_set_crypt(subreq, req->dst, req->dst,
8083b1bf	252	req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);
f1c131b4	253
78105c7e OM	254	/* calculate first value of T */
78105c7e OM	255	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
8083b1bf AB	256
8083b1bf AB	257	return 0;
f1c131b4 HX	258	}
f1c131b4 HX	259
a874f591	260	static int xts_encrypt(struct skcipher_request *req)
f1c131b4	261	{
a874f591	262	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	263	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	264	int err;
8083b1bf AB	265
a874f591 EB	266	err = xts_init_crypt(req, xts_encrypt_done) ?:
a874f591 EB	267	xts_xor_tweak_pre(req, true) ?:
8083b1bf	268	crypto_skcipher_encrypt(subreq) ?:
a874f591	269	xts_xor_tweak_post(req, true);
f1c131b4	270
8083b1bf AB	271	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	272	return err;
	273
a874f591	274	return xts_cts_final(req, crypto_skcipher_encrypt);
f1c131b4 HX	275	}
f1c131b4 HX	276
a874f591	277	static int xts_decrypt(struct skcipher_request *req)
f1c131b4	278	{
a874f591	279	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
78105c7e	280	struct skcipher_request *subreq = &rctx->subreq;
8083b1bf AB	281	int err;
8083b1bf AB	282
a874f591 EB	283	err = xts_init_crypt(req, xts_decrypt_done) ?:
a874f591 EB	284	xts_xor_tweak_pre(req, false) ?:
8083b1bf	285	crypto_skcipher_decrypt(subreq) ?:
a874f591	286	xts_xor_tweak_post(req, false);
8083b1bf AB	287
	288	if (err \|\| likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
	289	return err;
78105c7e	290
a874f591	291	return xts_cts_final(req, crypto_skcipher_decrypt);
f19f5111 RS	292	}
f19f5111 RS	293
a874f591	294	static int xts_init_tfm(struct crypto_skcipher *tfm)
f19f5111	295	{
f1c131b4 HX	296	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
f1c131b4 HX	297	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
a874f591	298	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
f1c131b4 HX	299	struct crypto_skcipher *child;
f1c131b4 HX	300	struct crypto_cipher *tweak;
f19f5111	301
f1c131b4 HX	302	child = crypto_spawn_skcipher(&ictx->spawn);
	303	if (IS_ERR(child))
	304	return PTR_ERR(child);
f19f5111	305
f1c131b4	306	ctx->child = child;
f19f5111	307
f1c131b4 HX	308	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
	309	if (IS_ERR(tweak)) {
	310	crypto_free_skcipher(ctx->child);
	311	return PTR_ERR(tweak);
f19f5111 RS	312	}
f19f5111 RS	313
f1c131b4 HX	314	ctx->tweak = tweak;
	315
	316	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
a874f591	317	sizeof(struct xts_request_ctx));
f19f5111 RS	318
	319	return 0;
	320	}
	321
a874f591	322	static void xts_exit_tfm(struct crypto_skcipher *tfm)
f19f5111	323	{
a874f591	324	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
f1c131b4 HX	325
f1c131b4 HX	326	crypto_free_skcipher(ctx->child);
f19f5111 RS	327	crypto_free_cipher(ctx->tweak);
	328	}
	329
a874f591	330	static void xts_free_instance(struct skcipher_instance *inst)
f1c131b4	331	{
a874f591 EB	332	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	333
	334	crypto_drop_skcipher(&ictx->spawn);
f1c131b4 HX	335	kfree(inst);
	336	}
	337
a874f591	338	static int xts_create(struct crypto_template tmpl, struct rtattr *tb)
f19f5111	339	{
f1c131b4	340	struct skcipher_instance *inst;
f1c131b4 HX	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
7bcb2c99 EB	347	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
	348	if (err)
	349	return err;
f1c131b4 HX	350
	351	cipher_name = crypto_attr_alg_name(tb[1]);
	352	if (IS_ERR(cipher_name))
	353	return PTR_ERR(cipher_name);
	354
	355	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	356	if (!inst)
	357	return -ENOMEM;
	358
	359	ctx = skcipher_instance_ctx(inst);
	360
b9f76ddd EB	361	err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst),
b9f76ddd EB	362	cipher_name, 0, mask);
f1c131b4 HX	363	if (err == -ENOENT) {
	364	err = -ENAMETOOLONG;
	365	if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	366	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	367	goto err_free_inst;
	368
b9f76ddd EB	369	err = crypto_grab_skcipher(&ctx->spawn,
	370	skcipher_crypto_instance(inst),
	371	ctx->name, 0, mask);
f1c131b4 HX	372	}
f1c131b4 HX	373
f19f5111	374	if (err)
f1c131b4	375	goto err_free_inst;
f19f5111	376
f1c131b4	377	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
f19f5111	378
f1c131b4 HX	379	err = -EINVAL;
f1c131b4 HX	380	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
732e5409	381	goto err_free_inst;
f19f5111	382
f1c131b4	383	if (crypto_skcipher_alg_ivsize(alg))
732e5409	384	goto err_free_inst;
f19f5111	385
f1c131b4 HX	386	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
	387	&alg->base);
	388	if (err)
732e5409	389	goto err_free_inst;
f19f5111	390
f1c131b4 HX	391	err = -EINVAL;
f1c131b4 HX	392	cipher_name = alg->base.cra_name;
f19f5111	393
f1c131b4 HX	394	/* Alas we screwed up the naming so we have to mangle the
	395	* cipher name.
	396	*/
	397	if (!strncmp(cipher_name, "ecb(", 4)) {
	398	unsigned len;
f19f5111	399
f1c131b4 HX	400	len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
f1c131b4 HX	401	if (len < 2 \|\| len >= sizeof(ctx->name))
732e5409	402	goto err_free_inst;
f19f5111	403
f1c131b4	404	if (ctx->name[len - 1] != ')')
732e5409	405	goto err_free_inst;
f19f5111	406
f1c131b4	407	ctx->name[len - 1] = 0;
f19f5111	408
f1c131b4	409	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
5125e4e8 CJ	410	"xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
5125e4e8 CJ	411	err = -ENAMETOOLONG;
732e5409	412	goto err_free_inst;
5125e4e8	413	}
f1c131b4	414	} else
732e5409	415	goto err_free_inst;
f19f5111	416
f1c131b4 HX	417	inst->alg.base.cra_priority = alg->base.cra_priority;
	418	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	419	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	420	(__alignof__(u64) - 1);
	421
	422	inst->alg.ivsize = XTS_BLOCK_SIZE;
	423	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	424	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
	425
a874f591	426	inst->alg.base.cra_ctxsize = sizeof(struct xts_tfm_ctx);
f1c131b4	427
a874f591 EB	428	inst->alg.init = xts_init_tfm;
a874f591 EB	429	inst->alg.exit = xts_exit_tfm;
f1c131b4	430
a874f591 EB	431	inst->alg.setkey = xts_setkey;
	432	inst->alg.encrypt = xts_encrypt;
	433	inst->alg.decrypt = xts_decrypt;
f1c131b4	434
a874f591	435	inst->free = xts_free_instance;
f1c131b4 HX	436
f1c131b4 HX	437	err = skcipher_register_instance(tmpl, inst);
732e5409	438	if (err) {
f1c131b4	439	err_free_inst:
a874f591	440	xts_free_instance(inst);
732e5409 EB	441	}
732e5409 EB	442	return err;
f19f5111 RS	443	}
f19f5111 RS	444
a874f591	445	static struct crypto_template xts_tmpl = {
f19f5111	446	.name = "xts",
a874f591	447	.create = xts_create,
f19f5111 RS	448	.module = THIS_MODULE,
	449	};
	450
a874f591	451	static int __init xts_module_init(void)
f19f5111	452	{
a874f591	453	return crypto_register_template(&xts_tmpl);
f19f5111 RS	454	}
f19f5111 RS	455
a874f591	456	static void __exit xts_module_exit(void)
f19f5111	457	{
a874f591	458	crypto_unregister_template(&xts_tmpl);
f19f5111 RS	459	}
f19f5111 RS	460
a874f591 EB	461	subsys_initcall(xts_module_init);
a874f591 EB	462	module_exit(xts_module_exit);
f19f5111 RS	463
	464	MODULE_LICENSE("GPL");
	465	MODULE_DESCRIPTION("XTS block cipher mode");
4943ba16	466	MODULE_ALIAS_CRYPTO("xts");