[linux.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 <[email protected]>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <[email protected]>
 *
 * 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 {
	be128 buf[XTS_BUFFER_SIZE / sizeof(be128)];

	be128 t;

	be128 *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);
	be128 *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;
		be128 *wdst;

		wdst = w.dst.virt.addr;

		do {
			be128_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);
	be128 *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;
		be128 *wsrc;
		be128 *wdst;

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

		do {
			*buf++ = rctx->t;
			be128_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) {
		subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
		rctx->ext = kmalloc(subreq->cryptlen, gfp);
	}

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

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

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

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

	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;
	be128 *src, *dst, *t;
	be128 *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 = (be128 *)walk.src.virt.addr;
	dst = (be128 *)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 */
				be128_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++)
				be128_xor(dst + i, dst + i, &t_buf[i]);

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

		*(be128 *)walk.iv = *t;

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

		nblocks = min(nbytes / bsize, max_blks);
		src = (be128 *)walk.src.virt.addr;
		dst = (be128 *)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;
	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));
	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0,
				   crypto_requires_sync(algt->type,
							algt->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,
					   crypto_requires_sync(algt->type,
								algt->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 <[email protected]>
	7	*
ddbc7361	8	* Based on ecb.c
f19f5111 RS	9	* Copyright (c) 2006 Herbert Xu <[email protected]>
	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 {
	42	be128 buf[XTS_BUFFER_SIZE / sizeof(be128)];
	43
	44	be128 t;
	45
	46	be128 *ext;
	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);
	102	be128 *buf = rctx->ext ?: rctx->buf;
	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) {
	114	unsigned int avail = w.nbytes;
	115	be128 *wdst;
f19f5111	116
f1c131b4 HX	117	wdst = w.dst.virt.addr;
	118
	119	do {
	120	be128_xor(wdst, buf++, wdst);
	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 HX	152	struct rctx *rctx = skcipher_request_ctx(req);
	153	be128 *buf = rctx->ext ?: rctx->buf;
	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) {
	176	unsigned int avail = w.nbytes;
	177	be128 *wsrc;
	178	be128 *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 {
	184	*buf++ = rctx->t;
	185	be128_xor(wdst++, &rctx->t, wsrc++);
	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) {
	233	subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
	234	rctx->ext = kmalloc(subreq->cryptlen, gfp);
	235	}
	236
	237	rctx->src = req->src;
	238	rctx->dst = req->dst;
	239	rctx->left = req->cryptlen;
f19f5111	240
f1c131b4 HX	241	/* calculate first value of T */
	242	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
	243
	244	return 0;
f19f5111 RS	245	}
f19f5111 RS	246
f1c131b4	247	static void exit_crypt(struct skcipher_request *req)
f19f5111	248	{
f1c131b4 HX	249	struct rctx *rctx = skcipher_request_ctx(req);
	250
	251	rctx->left = 0;
f19f5111	252
f1c131b4 HX	253	if (rctx->ext)
	254	kzfree(rctx->ext);
	255	}
	256
	257	static int do_encrypt(struct skcipher_request *req, int err)
	258	{
	259	struct rctx *rctx = skcipher_request_ctx(req);
	260	struct skcipher_request *subreq;
	261
	262	subreq = &rctx->subreq;
	263
	264	while (!err && rctx->left) {
	265	err = pre_crypt(req) ?:
	266	crypto_skcipher_encrypt(subreq) ?:
	267	post_crypt(req);
	268
	269	if (err == -EINPROGRESS \|\|
	270	(err == -EBUSY &&
	271	req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
	272	return err;
	273	}
	274
	275	exit_crypt(req);
	276	return err;
	277	}
	278
	279	static void encrypt_done(struct crypto_async_request *areq, int err)
	280	{
	281	struct skcipher_request *req = areq->data;
	282	struct skcipher_request *subreq;
	283	struct rctx *rctx;
	284
	285	rctx = skcipher_request_ctx(req);
	286	subreq = &rctx->subreq;
	287	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
	288
	289	err = do_encrypt(req, err ?: post_crypt(req));
	290	if (rctx->left)
	291	return;
	292
	293	skcipher_request_complete(req, err);
	294	}
	295
	296	static int encrypt(struct skcipher_request *req)
	297	{
	298	return do_encrypt(req, init_crypt(req, encrypt_done));
	299	}
	300
	301	static int do_decrypt(struct skcipher_request *req, int err)
	302	{
	303	struct rctx *rctx = skcipher_request_ctx(req);
	304	struct skcipher_request *subreq;
	305
	306	subreq = &rctx->subreq;
	307
	308	while (!err && rctx->left) {
	309	err = pre_crypt(req) ?:
	310	crypto_skcipher_decrypt(subreq) ?:
	311	post_crypt(req);
	312
	313	if (err == -EINPROGRESS \|\|
	314	(err == -EBUSY &&
	315	req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
	316	return err;
317	}
318
319	exit_crypt(req);
320	return err;
321	}
322
323	static void decrypt_done(struct crypto_async_request *areq, int err)
324	{
325	struct skcipher_request *req = areq->data;
326	struct skcipher_request *subreq;
327	struct rctx *rctx;
328
329	rctx = skcipher_request_ctx(req);
330	subreq = &rctx->subreq;
331	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
332
333	err = do_decrypt(req, err ?: post_crypt(req));
334	if (rctx->left)
335	return;
336
337	skcipher_request_complete(req, err);
338	}
339
340	static int decrypt(struct skcipher_request *req)
341	{
342	return do_decrypt(req, init_crypt(req, decrypt_done));
f19f5111 RS	343	}
f19f5111 RS	344
ce004556 JK	345	int xts_crypt(struct blkcipher_desc desc, struct scatterlist sdst,
	346	struct scatterlist *ssrc, unsigned int nbytes,
	347	struct xts_crypt_req *req)
	348	{
	349	const unsigned int bsize = XTS_BLOCK_SIZE;
	350	const unsigned int max_blks = req->tbuflen / bsize;
	351	struct blkcipher_walk walk;
	352	unsigned int nblocks;
	353	be128 src, dst, *t;
	354	be128 *t_buf = req->tbuf;
	355	int err, i;
	356
	357	BUG_ON(max_blks < 1);
	358
	359	blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
	360
	361	err = blkcipher_walk_virt(desc, &walk);
	362	nbytes = walk.nbytes;
	363	if (!nbytes)
	364	return err;
	365
	366	nblocks = min(nbytes / bsize, max_blks);
	367	src = (be128 *)walk.src.virt.addr;
	368	dst = (be128 *)walk.dst.virt.addr;
	369
	370	/* calculate first value of T */
	371	req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
	372
	373	i = 0;
	374	goto first;
	375
	376	for (;;) {
	377	do {
	378	for (i = 0; i < nblocks; i++) {
	379	gf128mul_x_ble(&t_buf[i], t);
	380	first:
	381	t = &t_buf[i];
	382
	383	/* PP <- T xor P */
	384	be128_xor(dst + i, t, src + i);
	385	}
	386
	387	/* CC <- E(Key2,PP) */
	388	req->crypt_fn(req->crypt_ctx, (u8 *)dst,
	389	nblocks * bsize);
	390
	391	/* C <- T xor CC */
	392	for (i = 0; i < nblocks; i++)
	393	be128_xor(dst + i, dst + i, &t_buf[i]);
	394
	395	src += nblocks;
	396	dst += nblocks;
	397	nbytes -= nblocks * bsize;
	398	nblocks = min(nbytes / bsize, max_blks);
	399	} while (nblocks > 0);
	400
	401	(be128 )walk.iv = *t;
	402
	403	err = blkcipher_walk_done(desc, &walk, nbytes);
	404	nbytes = walk.nbytes;
	405	if (!nbytes)
	406	break;
	407
	408	nblocks = min(nbytes / bsize, max_blks);
409	src = (be128 *)walk.src.virt.addr;
410	dst = (be128 *)walk.dst.virt.addr;
411	}
412
413	return err;
414	}
415	EXPORT_SYMBOL_GPL(xts_crypt);
416
f1c131b4	417	static int init_tfm(struct crypto_skcipher *tfm)
f19f5111	418	{
f1c131b4 HX	419	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	420	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
	421	struct priv *ctx = crypto_skcipher_ctx(tfm);
	422	struct crypto_skcipher *child;
	423	struct crypto_cipher *tweak;
f19f5111	424
f1c131b4 HX	425	child = crypto_spawn_skcipher(&ictx->spawn);
	426	if (IS_ERR(child))
	427	return PTR_ERR(child);
f19f5111	428
f1c131b4	429	ctx->child = child;
f19f5111	430
f1c131b4 HX	431	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
	432	if (IS_ERR(tweak)) {
	433	crypto_free_skcipher(ctx->child);
	434	return PTR_ERR(tweak);
f19f5111 RS	435	}
f19f5111 RS	436
f1c131b4 HX	437	ctx->tweak = tweak;
	438
	439	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
	440	sizeof(struct rctx));
f19f5111 RS	441
	442	return 0;
	443	}
	444
f1c131b4	445	static void exit_tfm(struct crypto_skcipher *tfm)
f19f5111	446	{
f1c131b4 HX	447	struct priv *ctx = crypto_skcipher_ctx(tfm);
	448
	449	crypto_free_skcipher(ctx->child);
f19f5111 RS	450	crypto_free_cipher(ctx->tweak);
	451	}
	452
f1c131b4 HX	453	static void free(struct skcipher_instance *inst)
	454	{
	455	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	456	kfree(inst);
	457	}
	458
	459	static int create(struct crypto_template tmpl, struct rtattr *tb)
f19f5111	460	{
f1c131b4 HX	461	struct skcipher_instance *inst;
	462	struct crypto_attr_type *algt;
	463	struct xts_instance_ctx *ctx;
	464	struct skcipher_alg *alg;
	465	const char *cipher_name;
f19f5111 RS	466	int err;
f19f5111 RS	467
f1c131b4 HX	468	algt = crypto_get_attr_type(tb);
	469	if (IS_ERR(algt))
	470	return PTR_ERR(algt);
	471
	472	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
	473	return -EINVAL;
	474
	475	cipher_name = crypto_attr_alg_name(tb[1]);
	476	if (IS_ERR(cipher_name))
	477	return PTR_ERR(cipher_name);
	478
	479	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	480	if (!inst)
	481	return -ENOMEM;
	482
	483	ctx = skcipher_instance_ctx(inst);
	484
	485	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
	486	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0,
	487	crypto_requires_sync(algt->type,
	488	algt->mask));
	489	if (err == -ENOENT) {
	490	err = -ENAMETOOLONG;
	491	if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	492	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	493	goto err_free_inst;
	494
	495	err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0,
	496	crypto_requires_sync(algt->type,
	497	algt->mask));
	498	}
	499
f19f5111	500	if (err)
f1c131b4	501	goto err_free_inst;
f19f5111	502
f1c131b4	503	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
f19f5111	504
f1c131b4 HX	505	err = -EINVAL;
	506	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
	507	goto err_drop_spawn;
f19f5111	508
f1c131b4 HX	509	if (crypto_skcipher_alg_ivsize(alg))
f1c131b4 HX	510	goto err_drop_spawn;
f19f5111	511
f1c131b4 HX	512	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
	513	&alg->base);
	514	if (err)
	515	goto err_drop_spawn;
f19f5111	516
f1c131b4 HX	517	err = -EINVAL;
f1c131b4 HX	518	cipher_name = alg->base.cra_name;
f19f5111	519
f1c131b4 HX	520	/* Alas we screwed up the naming so we have to mangle the
	521	* cipher name.
	522	*/
	523	if (!strncmp(cipher_name, "ecb(", 4)) {
	524	unsigned len;
f19f5111	525
f1c131b4 HX	526	len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
	527	if (len < 2 \|\| len >= sizeof(ctx->name))
	528	goto err_drop_spawn;
f19f5111	529
f1c131b4 HX	530	if (ctx->name[len - 1] != ')')
f1c131b4 HX	531	goto err_drop_spawn;
f19f5111	532
f1c131b4	533	ctx->name[len - 1] = 0;
f19f5111	534
f1c131b4 HX	535	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
	536	"xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME)
	537	return -ENAMETOOLONG;
	538	} else
	539	goto err_drop_spawn;
f19f5111	540
f1c131b4 HX	541	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	542	inst->alg.base.cra_priority = alg->base.cra_priority;
	543	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
	544	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
	545	(__alignof__(u64) - 1);
	546
	547	inst->alg.ivsize = XTS_BLOCK_SIZE;
	548	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
	549	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
	550
	551	inst->alg.base.cra_ctxsize = sizeof(struct priv);
	552
	553	inst->alg.init = init_tfm;
	554	inst->alg.exit = exit_tfm;
	555
	556	inst->alg.setkey = setkey;
	557	inst->alg.encrypt = encrypt;
	558	inst->alg.decrypt = decrypt;
	559
	560	inst->free = free;
	561
	562	err = skcipher_register_instance(tmpl, inst);
	563	if (err)
	564	goto err_drop_spawn;
	565
	566	out:
	567	return err;
	568
	569	err_drop_spawn:
	570	crypto_drop_skcipher(&ctx->spawn);
	571	err_free_inst:
f19f5111	572	kfree(inst);
f1c131b4	573	goto out;
f19f5111 RS	574	}
	575
	576	static struct crypto_template crypto_tmpl = {
	577	.name = "xts",
f1c131b4	578	.create = create,
f19f5111 RS	579	.module = THIS_MODULE,
	580	};
	581
	582	static int __init crypto_module_init(void)
	583	{
	584	return crypto_register_template(&crypto_tmpl);
	585	}
	586
	587	static void __exit crypto_module_exit(void)
	588	{
	589	crypto_unregister_template(&crypto_tmpl);
	590	}
	591
	592	module_init(crypto_module_init);
	593	module_exit(crypto_module_exit);
	594
	595	MODULE_LICENSE("GPL");
	596	MODULE_DESCRIPTION("XTS block cipher mode");
4943ba16	597	MODULE_ALIAS_CRYPTO("xts");