[mirror_ubuntu-artful-kernel.git] / crypto / xts.c

/* XTS: as defined in IEEE1619/D16
 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
 *	(sector sizes which are not a multiple of 16 bytes are,
 *	however currently unsupported)
 *
 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */
#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>

#define XTS_BUFFER_SIZE 128u

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 buf[XTS_BUFFER_SIZE / sizeof(le128)];

	le128 t;

	le128 *ext;

	struct scatterlist srcbuf[2];
	struct scatterlist dstbuf[2];
	struct scatterlist *src;
	struct scatterlist *dst;

	unsigned int left;

	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;
}

static int post_crypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	le128 *buf = rctx->ext ?: rctx->buf;
	struct skcipher_request *subreq;
	const int bs = XTS_BLOCK_SIZE;
	struct skcipher_walk w;
	struct scatterlist *sg;
	unsigned offset;
	int err;

	subreq = &rctx->subreq;
	err = skcipher_walk_virt(&w, subreq, false);

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

		wdst = w.dst.virt.addr;

		do {
			le128_xor(wdst, buf++, wdst);
			wdst++;
		} while ((avail -= bs) >= bs);

		err = skcipher_walk_done(&w, avail);
	}

	rctx->left -= subreq->cryptlen;

	if (err || !rctx->left)
		goto out;

	rctx->dst = rctx->dstbuf;

	scatterwalk_done(&w.out, 0, 1);
	sg = w.out.sg;
	offset = w.out.offset;

	if (rctx->dst != sg) {
		rctx->dst[0] = *sg;
		sg_unmark_end(rctx->dst);
		scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
	}
	rctx->dst[0].length -= offset - sg->offset;
	rctx->dst[0].offset = offset;

out:
	return err;
}

static int pre_crypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	le128 *buf = rctx->ext ?: rctx->buf;
	struct skcipher_request *subreq;
	const int bs = XTS_BLOCK_SIZE;
	struct skcipher_walk w;
	struct scatterlist *sg;
	unsigned cryptlen;
	unsigned offset;
	bool more;
	int err;

	subreq = &rctx->subreq;
	cryptlen = subreq->cryptlen;

	more = rctx->left > cryptlen;
	if (!more)
		cryptlen = rctx->left;

	skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
				   cryptlen, NULL);

	err = skcipher_walk_virt(&w, subreq, false);

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

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

		do {
			*buf++ = rctx->t;
			le128_xor(wdst++, &rctx->t, wsrc++);
			gf128mul_x_ble(&rctx->t, &rctx->t);
		} while ((avail -= bs) >= bs);

		err = skcipher_walk_done(&w, avail);
	}

	skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
				   cryptlen, NULL);

	if (err || !more)
		goto out;

	rctx->src = rctx->srcbuf;

	scatterwalk_done(&w.in, 0, 1);
	sg = w.in.sg;
	offset = w.in.offset;

	if (rctx->src != sg) {
		rctx->src[0] = *sg;
		sg_unmark_end(rctx->src);
		scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
	}
	rctx->src[0].length -= offset - sg->offset;
	rctx->src[0].offset = offset;

out:
	return err;
}

static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
{
	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq;
	gfp_t gfp;

	subreq = &rctx->subreq;
	skcipher_request_set_tfm(subreq, ctx->child);
	skcipher_request_set_callback(subreq, req->base.flags, done, req);

	gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
							   GFP_ATOMIC;
	rctx->ext = NULL;

	subreq->cryptlen = XTS_BUFFER_SIZE;
	if (req->cryptlen > XTS_BUFFER_SIZE) {
		unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);

		rctx->ext = kmalloc(n, gfp);
		if (rctx->ext)
			subreq->cryptlen = n;
	}

	rctx->src = req->src;
	rctx->dst = req->dst;
	rctx->left = req->cryptlen;

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

	return 0;
}

static void exit_crypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);

	rctx->left = 0;

	if (rctx->ext)
		kzfree(rctx->ext);
}

static int do_encrypt(struct skcipher_request *req, int err)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq;

	subreq = &rctx->subreq;

	while (!err && rctx->left) {
		err = pre_crypt(req) ?:
		      crypto_skcipher_encrypt(subreq) ?:
		      post_crypt(req);

		if (err == -EINPROGRESS ||
		    (err == -EBUSY &&
		     req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
			return err;
	}

	exit_crypt(req);
	return err;
}

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

	rctx = skcipher_request_ctx(req);

	if (err == -EINPROGRESS) {
		if (rctx->left != req->cryptlen)
			return;
		goto out;
	}

	subreq = &rctx->subreq;
	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;

	err = do_encrypt(req, err ?: post_crypt(req));
	if (rctx->left)
		return;

out:
	skcipher_request_complete(req, err);
}

static int encrypt(struct skcipher_request *req)
{
	return do_encrypt(req, init_crypt(req, encrypt_done));
}

static int do_decrypt(struct skcipher_request *req, int err)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq;

	subreq = &rctx->subreq;

	while (!err && rctx->left) {
		err = pre_crypt(req) ?:
		      crypto_skcipher_decrypt(subreq) ?:
		      post_crypt(req);

		if (err == -EINPROGRESS ||
		    (err == -EBUSY &&
		     req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
			return err;
	}

	exit_crypt(req);
	return err;
}

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

	rctx = skcipher_request_ctx(req);

	if (err == -EINPROGRESS) {
		if (rctx->left != req->cryptlen)
			return;
		goto out;
	}

	subreq = &rctx->subreq;
	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;

	err = do_decrypt(req, err ?: post_crypt(req));
	if (rctx->left)
		return;

out:
	skcipher_request_complete(req, err);
}

static int decrypt(struct skcipher_request *req)
{
	return do_decrypt(req, init_crypt(req, decrypt_done));
}

int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
	      struct scatterlist *ssrc, unsigned int nbytes,
	      struct xts_crypt_req *req)
{
	const unsigned int bsize = XTS_BLOCK_SIZE;
	const unsigned int max_blks = req->tbuflen / bsize;
	struct blkcipher_walk walk;
	unsigned int nblocks;
	le128 *src, *dst, *t;
	le128 *t_buf = req->tbuf;
	int err, i;

	BUG_ON(max_blks < 1);

	blkcipher_walk_init(&walk, sdst, ssrc, nbytes);

	err = blkcipher_walk_virt(desc, &walk);
	nbytes = walk.nbytes;
	if (!nbytes)
		return err;

	nblocks = min(nbytes / bsize, max_blks);
	src = (le128 *)walk.src.virt.addr;
	dst = (le128 *)walk.dst.virt.addr;

	/* calculate first value of T */
	req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);

	i = 0;
	goto first;

	for (;;) {
		do {
			for (i = 0; i < nblocks; i++) {
				gf128mul_x_ble(&t_buf[i], t);
first:
				t = &t_buf[i];

				/* PP <- T xor P */
				le128_xor(dst + i, t, src + i);
			}

			/* CC <- E(Key2,PP) */
			req->crypt_fn(req->crypt_ctx, (u8 *)dst,
				      nblocks * bsize);

			/* C <- T xor CC */
			for (i = 0; i < nblocks; i++)
				le128_xor(dst + i, dst + i, &t_buf[i]);

			src += nblocks;
			dst += nblocks;
			nbytes -= nblocks * bsize;
			nblocks = min(nbytes / bsize, max_blks);
		} while (nblocks > 0);

		*(le128 *)walk.iv = *t;

		err = blkcipher_walk_done(desc, &walk, nbytes);
		nbytes = walk.nbytes;
		if (!nbytes)
			break;

		nblocks = min(nbytes / bsize, max_blks);
		src = (le128 *)walk.src.virt.addr;
		dst = (le128 *)walk.dst.virt.addr;
	}

	return err;
}
EXPORT_SYMBOL_GPL(xts_crypt);

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)
			return -ENAMETOOLONG;
	} 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);
}

module_init(crypto_module_init);
module_exit(crypto_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XTS block cipher mode");
MODULE_ALIAS_CRYPTO("xts");
Commit	Line	Data
f19f5111 RS	1	/* XTS: as defined in IEEE1619/D16
	2	* http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
	3	* (sector sizes which are not a multiple of 16 bytes are,
	4	* however currently unsupported)
	5	*
	6	* Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
	7	*
ddbc7361	8	* Based on ecb.c
f19f5111 RS	9	* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
	10	*
	11	* This program is free software; you can redistribute it and/or modify it
	12	* under the terms of the GNU General Public License as published by the Free
	13	* Software Foundation; either version 2 of the License, or (at your option)
	14	* any later version.
	15	*/
f1c131b4 HX	16	#include <crypto/internal/skcipher.h>
f1c131b4 HX	17	#include <crypto/scatterwalk.h>
f19f5111 RS	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
ce004556	25	#include <crypto/xts.h>
f19f5111 RS	26	#include <crypto/b128ops.h>
	27	#include <crypto/gf128mul.h>
	28
f1c131b4 HX	29	#define XTS_BUFFER_SIZE 128u
f1c131b4 HX	30
f19f5111	31	struct priv {
f1c131b4	32	struct crypto_skcipher *child;
f19f5111 RS	33	struct crypto_cipher *tweak;
	34	};
	35
f1c131b4 HX	36	struct xts_instance_ctx {
	37	struct crypto_skcipher_spawn spawn;
	38	char name[CRYPTO_MAX_ALG_NAME];
	39	};
	40
	41	struct rctx {
e55318c8	42	le128 buf[XTS_BUFFER_SIZE / sizeof(le128)];
f1c131b4	43
e55318c8	44	le128 t;
f1c131b4	45
e55318c8	46	le128 *ext;
f1c131b4 HX	47
	48	struct scatterlist srcbuf[2];
	49	struct scatterlist dstbuf[2];
	50	struct scatterlist *src;
	51	struct scatterlist *dst;
	52
	53	unsigned int left;
	54
	55	struct skcipher_request subreq;
	56	};
	57
	58	static int setkey(struct crypto_skcipher parent, const u8 key,
f19f5111 RS	59	unsigned int keylen)
f19f5111 RS	60	{
f1c131b4 HX	61	struct priv *ctx = crypto_skcipher_ctx(parent);
	62	struct crypto_skcipher *child;
	63	struct crypto_cipher *tweak;
f19f5111 RS	64	int err;
f19f5111 RS	65
f1c131b4	66	err = xts_verify_key(parent, key, keylen);
28856a9e SM	67	if (err)
28856a9e SM	68	return err;
f19f5111	69
f1c131b4 HX	70	keylen /= 2;
f1c131b4 HX	71
25985edc	72	/* we need two cipher instances: one to compute the initial 'tweak'
f19f5111 RS	73	* by encrypting the IV (usually the 'plain' iv) and the other
	74	* one to encrypt and decrypt the data */
	75
	76	/* tweak cipher, uses Key2 i.e. the second half of key /
f1c131b4 HX	77	tweak = ctx->tweak;
	78	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
	79	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
f19f5111	80	CRYPTO_TFM_REQ_MASK);
f1c131b4 HX	81	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
	82	crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
	83	CRYPTO_TFM_RES_MASK);
f19f5111 RS	84	if (err)
	85	return err;
	86
f1c131b4	87	/* data cipher, uses Key1 i.e. the first half of key /
f19f5111	88	child = ctx->child;
f1c131b4 HX	89	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	90	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	91	CRYPTO_TFM_REQ_MASK);
	92	err = crypto_skcipher_setkey(child, key, keylen);
	93	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
	94	CRYPTO_TFM_RES_MASK);
f19f5111	95
f1c131b4 HX	96	return err;
f1c131b4 HX	97	}
f19f5111	98
f1c131b4 HX	99	static int post_crypt(struct skcipher_request *req)
	100	{
	101	struct rctx *rctx = skcipher_request_ctx(req);
e55318c8	102	le128 *buf = rctx->ext ?: rctx->buf;
f1c131b4 HX	103	struct skcipher_request *subreq;
	104	const int bs = XTS_BLOCK_SIZE;
	105	struct skcipher_walk w;
	106	struct scatterlist *sg;
	107	unsigned offset;
	108	int err;
f19f5111	109
f1c131b4 HX	110	subreq = &rctx->subreq;
f1c131b4 HX	111	err = skcipher_walk_virt(&w, subreq, false);
f19f5111	112
f1c131b4 HX	113	while (w.nbytes) {
f1c131b4 HX	114	unsigned int avail = w.nbytes;
e55318c8	115	le128 *wdst;
f19f5111	116
f1c131b4 HX	117	wdst = w.dst.virt.addr;
	118
	119	do {
e55318c8	120	le128_xor(wdst, buf++, wdst);
f1c131b4 HX	121	wdst++;
	122	} while ((avail -= bs) >= bs);
	123
	124	err = skcipher_walk_done(&w, avail);
	125	}
	126
	127	rctx->left -= subreq->cryptlen;
	128
	129	if (err \|\| !rctx->left)
	130	goto out;
	131
	132	rctx->dst = rctx->dstbuf;
	133
	134	scatterwalk_done(&w.out, 0, 1);
	135	sg = w.out.sg;
	136	offset = w.out.offset;
	137
	138	if (rctx->dst != sg) {
	139	rctx->dst[0] = *sg;
	140	sg_unmark_end(rctx->dst);
	141	scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
	142	}
	143	rctx->dst[0].length -= offset - sg->offset;
	144	rctx->dst[0].offset = offset;
	145
	146	out:
	147	return err;
f19f5111 RS	148	}
f19f5111 RS	149
f1c131b4	150	static int pre_crypt(struct skcipher_request *req)
f19f5111	151	{
f1c131b4	152	struct rctx *rctx = skcipher_request_ctx(req);
e55318c8	153	le128 *buf = rctx->ext ?: rctx->buf;
f1c131b4	154	struct skcipher_request *subreq;
f9d2691f	155	const int bs = XTS_BLOCK_SIZE;
f1c131b4 HX	156	struct skcipher_walk w;
	157	struct scatterlist *sg;
	158	unsigned cryptlen;
	159	unsigned offset;
	160	bool more;
	161	int err;
f19f5111	162
f1c131b4 HX	163	subreq = &rctx->subreq;
f1c131b4 HX	164	cryptlen = subreq->cryptlen;
f19f5111	165
f1c131b4 HX	166	more = rctx->left > cryptlen;
	167	if (!more)
	168	cryptlen = rctx->left;
f19f5111	169
f1c131b4 HX	170	skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
f1c131b4 HX	171	cryptlen, NULL);
f19f5111	172
f1c131b4	173	err = skcipher_walk_virt(&w, subreq, false);
f19f5111	174
f1c131b4 HX	175	while (w.nbytes) {
f1c131b4 HX	176	unsigned int avail = w.nbytes;
e55318c8 OM	177	le128 *wsrc;
e55318c8 OM	178	le128 *wdst;
f19f5111	179
f1c131b4 HX	180	wsrc = w.src.virt.addr;
f1c131b4 HX	181	wdst = w.dst.virt.addr;
f19f5111	182
f1c131b4 HX	183	do {
f1c131b4 HX	184	*buf++ = rctx->t;
e55318c8	185	le128_xor(wdst++, &rctx->t, wsrc++);
f1c131b4	186	gf128mul_x_ble(&rctx->t, &rctx->t);
f19f5111 RS	187	} while ((avail -= bs) >= bs);
f19f5111 RS	188
f1c131b4 HX	189	err = skcipher_walk_done(&w, avail);
	190	}
	191
	192	skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
	193	cryptlen, NULL);
f19f5111	194
f1c131b4 HX	195	if (err \|\| !more)
f1c131b4 HX	196	goto out;
f19f5111	197
f1c131b4 HX	198	rctx->src = rctx->srcbuf;
	199
	200	scatterwalk_done(&w.in, 0, 1);
	201	sg = w.in.sg;
	202	offset = w.in.offset;
	203
	204	if (rctx->src != sg) {
	205	rctx->src[0] = *sg;
	206	sg_unmark_end(rctx->src);
	207	scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
f19f5111	208	}
f1c131b4 HX	209	rctx->src[0].length -= offset - sg->offset;
f1c131b4 HX	210	rctx->src[0].offset = offset;
f19f5111	211
f1c131b4	212	out:
f19f5111 RS	213	return err;
	214	}
	215
f1c131b4	216	static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
f19f5111	217	{
f1c131b4 HX	218	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	219	struct rctx *rctx = skcipher_request_ctx(req);
	220	struct skcipher_request *subreq;
	221	gfp_t gfp;
	222
	223	subreq = &rctx->subreq;
	224	skcipher_request_set_tfm(subreq, ctx->child);
	225	skcipher_request_set_callback(subreq, req->base.flags, done, req);
	226
	227	gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
	228	GFP_ATOMIC;
	229	rctx->ext = NULL;
	230
	231	subreq->cryptlen = XTS_BUFFER_SIZE;
	232	if (req->cryptlen > XTS_BUFFER_SIZE) {
9df0eb18 EB	233	unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
	234
	235	rctx->ext = kmalloc(n, gfp);
	236	if (rctx->ext)
	237	subreq->cryptlen = n;
f1c131b4 HX	238	}
	239
	240	rctx->src = req->src;
	241	rctx->dst = req->dst;
	242	rctx->left = req->cryptlen;
f19f5111	243
f1c131b4 HX	244	/* calculate first value of T */
	245	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
	246
	247	return 0;
f19f5111 RS	248	}
f19f5111 RS	249
f1c131b4	250	static void exit_crypt(struct skcipher_request *req)
f19f5111	251	{
f1c131b4 HX	252	struct rctx *rctx = skcipher_request_ctx(req);
	253
	254	rctx->left = 0;
f19f5111	255
f1c131b4 HX	256	if (rctx->ext)
	257	kzfree(rctx->ext);
	258	}
	259
	260	static int do_encrypt(struct skcipher_request *req, int err)
	261	{
	262	struct rctx *rctx = skcipher_request_ctx(req);
	263	struct skcipher_request *subreq;
	264
	265	subreq = &rctx->subreq;
	266
	267	while (!err && rctx->left) {
	268	err = pre_crypt(req) ?:
	269	crypto_skcipher_encrypt(subreq) ?:
	270	post_crypt(req);
	271
	272	if (err == -EINPROGRESS \|\|
	273	(err == -EBUSY &&
	274	req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
	275	return err;
	276	}
	277
	278	exit_crypt(req);
	279	return err;
	280	}
	281
	282	static void encrypt_done(struct crypto_async_request *areq, int err)
	283	{
	284	struct skcipher_request *req = areq->data;
	285	struct skcipher_request *subreq;
	286	struct rctx *rctx;
	287
	288	rctx = skcipher_request_ctx(req);
aa4a829b HX	289
	290	if (err == -EINPROGRESS) {
	291	if (rctx->left != req->cryptlen)
	292	return;
	293	goto out;
	294	}
	295
f1c131b4 HX	296	subreq = &rctx->subreq;
	297	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
	298
	299	err = do_encrypt(req, err ?: post_crypt(req));
	300	if (rctx->left)
	301	return;
	302
aa4a829b	303	out:
f1c131b4 HX	304	skcipher_request_complete(req, err);
	305	}
	306
	307	static int encrypt(struct skcipher_request *req)
	308	{
	309	return do_encrypt(req, init_crypt(req, encrypt_done));
	310	}
	311
	312	static int do_decrypt(struct skcipher_request *req, int err)
	313	{
	314	struct rctx *rctx = skcipher_request_ctx(req);
	315	struct skcipher_request *subreq;
	316
	317	subreq = &rctx->subreq;
	318
	319	while (!err && rctx->left) {
	320	err = pre_crypt(req) ?:
	321	crypto_skcipher_decrypt(subreq) ?:
	322	post_crypt(req);
	323
	324	if (err == -EINPROGRESS \|\|
	325	(err == -EBUSY &&
	326	req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
	327	return err;
	328	}
	329
	330	exit_crypt(req);
	331	return err;
	332	}
	333
	334	static void decrypt_done(struct crypto_async_request *areq, int err)
	335	{
	336	struct skcipher_request *req = areq->data;
	337	struct skcipher_request *subreq;
	338	struct rctx *rctx;
	339
	340	rctx = skcipher_request_ctx(req);
aa4a829b HX	341
	342	if (err == -EINPROGRESS) {
	343	if (rctx->left != req->cryptlen)
	344	return;
	345	goto out;
	346	}
	347
f1c131b4 HX	348	subreq = &rctx->subreq;
	349	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
	350
	351	err = do_decrypt(req, err ?: post_crypt(req));
	352	if (rctx->left)
	353	return;
	354
aa4a829b	355	out:
f1c131b4 HX	356	skcipher_request_complete(req, err);
	357	}
	358
	359	static int decrypt(struct skcipher_request *req)
	360	{
	361	return do_decrypt(req, init_crypt(req, decrypt_done));
f19f5111 RS	362	}
f19f5111 RS	363
ce004556 JK	364	int xts_crypt(struct blkcipher_desc desc, struct scatterlist sdst,
	365	struct scatterlist *ssrc, unsigned int nbytes,
	366	struct xts_crypt_req *req)
	367	{
	368	const unsigned int bsize = XTS_BLOCK_SIZE;
	369	const unsigned int max_blks = req->tbuflen / bsize;
	370	struct blkcipher_walk walk;
	371	unsigned int nblocks;
e55318c8 OM	372	le128 src, dst, *t;
e55318c8 OM	373	le128 *t_buf = req->tbuf;
ce004556 JK	374	int err, i;
	375
	376	BUG_ON(max_blks < 1);
	377
	378	blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
	379
	380	err = blkcipher_walk_virt(desc, &walk);
	381	nbytes = walk.nbytes;
	382	if (!nbytes)
	383	return err;
	384
	385	nblocks = min(nbytes / bsize, max_blks);
e55318c8 OM	386	src = (le128 *)walk.src.virt.addr;
e55318c8 OM	387	dst = (le128 *)walk.dst.virt.addr;
ce004556 JK	388
	389	/* calculate first value of T */
	390	req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
	391
	392	i = 0;
	393	goto first;
	394
	395	for (;;) {
	396	do {
	397	for (i = 0; i < nblocks; i++) {
	398	gf128mul_x_ble(&t_buf[i], t);
	399	first:
	400	t = &t_buf[i];
	401
	402	/* PP <- T xor P */
e55318c8	403	le128_xor(dst + i, t, src + i);
ce004556 JK	404	}
	405
	406	/* CC <- E(Key2,PP) */
	407	req->crypt_fn(req->crypt_ctx, (u8 *)dst,
	408	nblocks * bsize);
	409
	410	/* C <- T xor CC */
	411	for (i = 0; i < nblocks; i++)
e55318c8	412	le128_xor(dst + i, dst + i, &t_buf[i]);
ce004556 JK	413
	414	src += nblocks;
	415	dst += nblocks;
	416	nbytes -= nblocks * bsize;
	417	nblocks = min(nbytes / bsize, max_blks);
	418	} while (nblocks > 0);
	419
e55318c8	420	(le128 )walk.iv = *t;
ce004556 JK	421
	422	err = blkcipher_walk_done(desc, &walk, nbytes);
	423	nbytes = walk.nbytes;
	424	if (!nbytes)
	425	break;
	426
	427	nblocks = min(nbytes / bsize, max_blks);
e55318c8 OM	428	src = (le128 *)walk.src.virt.addr;
e55318c8 OM	429	dst = (le128 *)walk.dst.virt.addr;
ce004556 JK	430	}
	431
	432	return err;
	433	}
	434	EXPORT_SYMBOL_GPL(xts_crypt);
	435
f1c131b4	436	static int init_tfm(struct crypto_skcipher *tfm)
f19f5111	437	{
f1c131b4 HX	438	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	439	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	440	struct priv *ctx = crypto_skcipher_ctx(tfm);
	441	struct crypto_skcipher *child;
	442	struct crypto_cipher *tweak;
f19f5111	443
f1c131b4 HX	444	child = crypto_spawn_skcipher(&ictx->spawn);
	445	if (IS_ERR(child))
	446	return PTR_ERR(child);
f19f5111	447
f1c131b4	448	ctx->child = child;
f19f5111	449
f1c131b4 HX	450	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
	451	if (IS_ERR(tweak)) {
	452	crypto_free_skcipher(ctx->child);
	453	return PTR_ERR(tweak);
f19f5111 RS	454	}
f19f5111 RS	455
f1c131b4 HX	456	ctx->tweak = tweak;
	457
	458	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
	459	sizeof(struct rctx));
f19f5111 RS	460
	461	return 0;
	462	}
	463
f1c131b4	464	static void exit_tfm(struct crypto_skcipher *tfm)
f19f5111	465	{
f1c131b4 HX	466	struct priv *ctx = crypto_skcipher_ctx(tfm);
	467
	468	crypto_free_skcipher(ctx->child);
f19f5111 RS	469	crypto_free_cipher(ctx->tweak);
	470	}
	471
f1c131b4 HX	472	static void free(struct skcipher_instance *inst)
	473	{
	474	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	475	kfree(inst);
	476	}
	477
	478	static int create(struct crypto_template tmpl, struct rtattr *tb)
f19f5111	479	{
f1c131b4 HX	480	struct skcipher_instance *inst;
	481	struct crypto_attr_type *algt;
	482	struct xts_instance_ctx *ctx;
	483	struct skcipher_alg *alg;
	484	const char *cipher_name;
89027579	485	u32 mask;
f19f5111 RS	486	int err;
f19f5111 RS	487
f1c131b4 HX	488	algt = crypto_get_attr_type(tb);
	489	if (IS_ERR(algt))
	490	return PTR_ERR(algt);
	491
	492	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
	493	return -EINVAL;
	494
	495	cipher_name = crypto_attr_alg_name(tb[1]);
	496	if (IS_ERR(cipher_name))
	497	return PTR_ERR(cipher_name);
	498
	499	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	500	if (!inst)
	501	return -ENOMEM;
	502
	503	ctx = skcipher_instance_ctx(inst);
	504
	505	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
89027579 HX	506
	507	mask = crypto_requires_off(algt->type, algt->mask,
	508	CRYPTO_ALG_NEED_FALLBACK \|
	509	CRYPTO_ALG_ASYNC);
	510
	511	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
f1c131b4 HX	512	if (err == -ENOENT) {
	513	err = -ENAMETOOLONG;
	514	if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	515	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	516	goto err_free_inst;
	517
89027579	518	err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
f1c131b4 HX	519	}
f1c131b4 HX	520
f19f5111	521	if (err)
f1c131b4	522	goto err_free_inst;
f19f5111	523
f1c131b4	524	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
f19f5111	525
f1c131b4 HX	526	err = -EINVAL;
	527	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
	528	goto err_drop_spawn;
f19f5111	529
f1c131b4 HX	530	if (crypto_skcipher_alg_ivsize(alg))
f1c131b4 HX	531	goto err_drop_spawn;
f19f5111	532
f1c131b4 HX	533	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
	534	&alg->base);
	535	if (err)
	536	goto err_drop_spawn;
f19f5111	537
f1c131b4 HX	538	err = -EINVAL;
f1c131b4 HX	539	cipher_name = alg->base.cra_name;
f19f5111	540
f1c131b4 HX	541	/* Alas we screwed up the naming so we have to mangle the
	542	* cipher name.
	543	*/
	544	if (!strncmp(cipher_name, "ecb(", 4)) {
	545	unsigned len;
f19f5111	546
f1c131b4 HX	547	len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
	548	if (len < 2 \|\| len >= sizeof(ctx->name))
	549	goto err_drop_spawn;
f19f5111	550
f1c131b4 HX	551	if (ctx->name[len - 1] != ')')
f1c131b4 HX	552	goto err_drop_spawn;
f19f5111	553
f1c131b4	554	ctx->name[len - 1] = 0;
f19f5111	555
f1c131b4 HX	556	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
	557	"xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME)
	558	return -ENAMETOOLONG;
	559	} else
	560	goto err_drop_spawn;
f19f5111	561
f1c131b4 HX	562	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	563	inst->alg.base.cra_priority = alg->base.cra_priority;
	564	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	565	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	566	(__alignof__(u64) - 1);
	567
	568	inst->alg.ivsize = XTS_BLOCK_SIZE;
	569	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	570	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
	571
	572	inst->alg.base.cra_ctxsize = sizeof(struct priv);
	573
	574	inst->alg.init = init_tfm;
	575	inst->alg.exit = exit_tfm;
	576
	577	inst->alg.setkey = setkey;
	578	inst->alg.encrypt = encrypt;
	579	inst->alg.decrypt = decrypt;
	580
	581	inst->free = free;
	582
	583	err = skcipher_register_instance(tmpl, inst);
	584	if (err)
	585	goto err_drop_spawn;
	586
	587	out:
	588	return err;
	589
	590	err_drop_spawn:
	591	crypto_drop_skcipher(&ctx->spawn);
	592	err_free_inst:
f19f5111	593	kfree(inst);
f1c131b4	594	goto out;
f19f5111 RS	595	}
	596
	597	static struct crypto_template crypto_tmpl = {
	598	.name = "xts",
f1c131b4	599	.create = create,
f19f5111 RS	600	.module = THIS_MODULE,
	601	};
	602
	603	static int __init crypto_module_init(void)
	604	{
	605	return crypto_register_template(&crypto_tmpl);
	606	}
	607
	608	static void __exit crypto_module_exit(void)
	609	{
	610	crypto_unregister_template(&crypto_tmpl);
	611	}
	612
	613	module_init(crypto_module_init);
	614	module_exit(crypto_module_exit);
	615
	616	MODULE_LICENSE("GPL");
	617	MODULE_DESCRIPTION("XTS block cipher mode");
4943ba16	618	MODULE_ALIAS_CRYPTO("xts");