crypto/xts.c - third_party/linux - Git at Google

 /* 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 om 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/algapi.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/b128ops.h>
 #include <crypto/gf128mul.h>

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

 static int setkey(struct crypto_tfm *parent, const u8 *key,
 		  unsigned int keylen)
 {
 	struct priv *ctx = crypto_tfm_ctx(parent);
 	struct crypto_cipher *child = ctx->tweak;
 	u32 *flags = &parent->crt_flags;
 	int err;

 	/* key consists of keys of equal size concatenated, therefore
 	 * the length must be even */
 	if (keylen % 2) {
 		/* tell the user why there was an error */
 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 		return -EINVAL;
 	}

 	/* 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 */
 	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 				       CRYPTO_TFM_REQ_MASK);
 	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
 	if (err)
 		return err;

 	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 				     CRYPTO_TFM_RES_MASK);

 	child = ctx->child;

 	/* data cipher, uses Key1 i.e. the first half of *key */
 	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 				       CRYPTO_TFM_REQ_MASK);
 	err = crypto_cipher_setkey(child, key, keylen/2);
 	if (err)
 		return err;

 	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 				     CRYPTO_TFM_RES_MASK);

 	return 0;
 }

 struct sinfo {
 	be128 *t;
 	struct crypto_tfm *tfm;
 	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 };

 static inline void xts_round(struct sinfo *s, void *dst, const void *src)
 {
 	be128_xor(dst, s->t, src);		/* PP <- T xor P */
 	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */
 	be128_xor(dst, dst, s->t);		/* C <- T xor CC */
 }

 static int crypt(struct blkcipher_desc *d,
 		 struct blkcipher_walk *w, struct priv *ctx,
 		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
 		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
 {
 	int err;
 	unsigned int avail;
 	const int bs = crypto_cipher_blocksize(ctx->child);
 	struct sinfo s = {
 		.tfm = crypto_cipher_tfm(ctx->child),
 		.fn = fn
 	};
 	u8 *wsrc;
 	u8 *wdst;

 	err = blkcipher_walk_virt(d, w);
 	if (!w->nbytes)
 		return err;

 	s.t = (be128 *)w->iv;
 	avail = w->nbytes;

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

 	/* calculate first value of T */
 	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);

 	goto first;

 	for (;;) {
 		do {
 			gf128mul_x_ble(s.t, s.t);

 first:
 			xts_round(&s, wdst, wsrc);

 			wsrc += bs;
 			wdst += bs;
 		} while ((avail -= bs) >= bs);

 		err = blkcipher_walk_done(d, w, avail);
 		if (!w->nbytes)
 			break;

 		avail = w->nbytes;

 		wsrc = w->src.virt.addr;
 		wdst = w->dst.virt.addr;
 	}

 	return err;
 }

 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
 		   struct scatterlist *src, unsigned int nbytes)
 {
 	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
 	struct blkcipher_walk w;

 	blkcipher_walk_init(&w, dst, src, nbytes);
 	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
 		     crypto_cipher_alg(ctx->child)->cia_encrypt);
 }

 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
 		   struct scatterlist *src, unsigned int nbytes)
 {
 	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
 	struct blkcipher_walk w;

 	blkcipher_walk_init(&w, dst, src, nbytes);
 	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
 		     crypto_cipher_alg(ctx->child)->cia_decrypt);
 }

 static int init_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_cipher *cipher;
 	struct crypto_instance *inst = (void *)tfm->__crt_alg;
 	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 	struct priv *ctx = crypto_tfm_ctx(tfm);
 	u32 *flags = &tfm->crt_flags;

 	cipher = crypto_spawn_cipher(spawn);
 	if (IS_ERR(cipher))
 		return PTR_ERR(cipher);

 	if (crypto_cipher_blocksize(cipher) != 16) {
 		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 		crypto_free_cipher(cipher);
 		return -EINVAL;
 	}

 	ctx->child = cipher;

 	cipher = crypto_spawn_cipher(spawn);
 	if (IS_ERR(cipher)) {
 		crypto_free_cipher(ctx->child);
 		return PTR_ERR(cipher);
 	}

 	/* this check isn't really needed, leave it here just in case */
 	if (crypto_cipher_blocksize(cipher) != 16) {
 		crypto_free_cipher(cipher);
 		crypto_free_cipher(ctx->child);
 		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 		return -EINVAL;
 	}

 	ctx->tweak = cipher;

 	return 0;
 }

 static void exit_tfm(struct crypto_tfm *tfm)
 {
 	struct priv *ctx = crypto_tfm_ctx(tfm);
 	crypto_free_cipher(ctx->child);
 	crypto_free_cipher(ctx->tweak);
 }

 static struct crypto_instance *alloc(struct rtattr **tb)
 {
 	struct crypto_instance *inst;
 	struct crypto_alg *alg;
 	int err;

 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
 	if (err)
 		return ERR_PTR(err);

 	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 				  CRYPTO_ALG_TYPE_MASK);
 	if (IS_ERR(alg))
 		return ERR_CAST(alg);

 	inst = crypto_alloc_instance("xts", alg);
 	if (IS_ERR(inst))
 		goto out_put_alg;

 	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 	inst->alg.cra_priority = alg->cra_priority;
 	inst->alg.cra_blocksize = alg->cra_blocksize;

 	if (alg->cra_alignmask < 7)
 		inst->alg.cra_alignmask = 7;
 	else
 		inst->alg.cra_alignmask = alg->cra_alignmask;

 	inst->alg.cra_type = &crypto_blkcipher_type;

 	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
 	inst->alg.cra_blkcipher.min_keysize =
 		2 * alg->cra_cipher.cia_min_keysize;
 	inst->alg.cra_blkcipher.max_keysize =
 		2 * alg->cra_cipher.cia_max_keysize;

 	inst->alg.cra_ctxsize = sizeof(struct priv);

 	inst->alg.cra_init = init_tfm;
 	inst->alg.cra_exit = exit_tfm;

 	inst->alg.cra_blkcipher.setkey = setkey;
 	inst->alg.cra_blkcipher.encrypt = encrypt;
 	inst->alg.cra_blkcipher.decrypt = decrypt;

 out_put_alg:
 	crypto_mod_put(alg);
 	return inst;
 }

 static void free(struct crypto_instance *inst)
 {
 	crypto_drop_spawn(crypto_instance_ctx(inst));
 	kfree(inst);
 }

 static struct crypto_template crypto_tmpl = {
 	.name = "xts",
 	.alloc = alloc,
 	.free = free,
 	.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");
	/* 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 om 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/algapi.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/b128ops.h>
	#include <crypto/gf128mul.h>

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

	static int setkey(struct crypto_tfm parent, const u8 key,
	unsigned int keylen)
	{
	struct priv *ctx = crypto_tfm_ctx(parent);
	struct crypto_cipher *child = ctx->tweak;
	u32 *flags = &parent->crt_flags;
	int err;

	/* key consists of keys of equal size concatenated, therefore
	* the length must be even */
	if (keylen % 2) {
	/* tell the user why there was an error */
	*flags \|= CRYPTO_TFM_RES_BAD_KEY_LEN;
	return -EINVAL;
	}

	/* 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 /
	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
	CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
	if (err)
	return err;

	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
	CRYPTO_TFM_RES_MASK);

	child = ctx->child;

	/* data cipher, uses Key1 i.e. the first half of key /
	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
	CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key, keylen/2);
	if (err)
	return err;

	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
	CRYPTO_TFM_RES_MASK);

	return 0;
	}

	struct sinfo {
	be128 *t;
	struct crypto_tfm *tfm;
	void (fn)(struct crypto_tfm , u8 , const u8 );
	};

	static inline void xts_round(struct sinfo s, void dst, const void *src)
	{
	be128_xor(dst, s->t, src); /* PP <- T xor P */
	s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
	be128_xor(dst, dst, s->t); /* C <- T xor CC */
	}

	static int crypt(struct blkcipher_desc *d,
	struct blkcipher_walk w, struct priv ctx,
	void (tw)(struct crypto_tfm , u8 , const u8 ),
	void (fn)(struct crypto_tfm , u8 , const u8 ))
	{
	int err;
	unsigned int avail;
	const int bs = crypto_cipher_blocksize(ctx->child);
	struct sinfo s = {
	.tfm = crypto_cipher_tfm(ctx->child),
	.fn = fn
	};
	u8 *wsrc;
	u8 *wdst;

	err = blkcipher_walk_virt(d, w);
	if (!w->nbytes)
	return err;

	s.t = (be128 *)w->iv;
	avail = w->nbytes;

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

	/* calculate first value of T */
	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);

	goto first;

	for (;;) {
	do {
	gf128mul_x_ble(s.t, s.t);

	first:
	xts_round(&s, wdst, wsrc);

	wsrc += bs;
	wdst += bs;
	} while ((avail -= bs) >= bs);

	err = blkcipher_walk_done(d, w, avail);
	if (!w->nbytes)
	break;

	avail = w->nbytes;

	wsrc = w->src.virt.addr;
	wdst = w->dst.virt.addr;
	}

	return err;
	}

	static int encrypt(struct blkcipher_desc desc, struct scatterlist dst,
	struct scatterlist *src, unsigned int nbytes)
	{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
	crypto_cipher_alg(ctx->child)->cia_encrypt);
	}

	static int decrypt(struct blkcipher_desc desc, struct scatterlist dst,
	struct scatterlist *src, unsigned int nbytes)
	{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
	crypto_cipher_alg(ctx->child)->cia_decrypt);
	}

	static int init_tfm(struct crypto_tfm *tfm)
	{
	struct crypto_cipher *cipher;
	struct crypto_instance inst = (void )tfm->__crt_alg;
	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	struct priv *ctx = crypto_tfm_ctx(tfm);
	u32 *flags = &tfm->crt_flags;

	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher))
	return PTR_ERR(cipher);

	if (crypto_cipher_blocksize(cipher) != 16) {
	*flags \|= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
	crypto_free_cipher(cipher);
	return -EINVAL;
	}

	ctx->child = cipher;

	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher)) {
	crypto_free_cipher(ctx->child);
	return PTR_ERR(cipher);
	}

	/* this check isn't really needed, leave it here just in case */
	if (crypto_cipher_blocksize(cipher) != 16) {
	crypto_free_cipher(cipher);
	crypto_free_cipher(ctx->child);
	*flags \|= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
	return -EINVAL;
	}

	ctx->tweak = cipher;

	return 0;
	}

	static void exit_tfm(struct crypto_tfm *tfm)
	{
	struct priv *ctx = crypto_tfm_ctx(tfm);
	crypto_free_cipher(ctx->child);
	crypto_free_cipher(ctx->tweak);
	}

	static struct crypto_instance alloc(struct rtattr *tb)
	{
	struct crypto_instance *inst;
	struct crypto_alg *alg;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	if (err)
	return ERR_PTR(err);

	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
	CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
	return ERR_CAST(alg);

	inst = crypto_alloc_instance("xts", alg);
	if (IS_ERR(inst))
	goto out_put_alg;

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = alg->cra_blocksize;

	if (alg->cra_alignmask < 7)
	inst->alg.cra_alignmask = 7;
	else
	inst->alg.cra_alignmask = alg->cra_alignmask;

	inst->alg.cra_type = &crypto_blkcipher_type;

	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	inst->alg.cra_blkcipher.min_keysize =
	2 * alg->cra_cipher.cia_min_keysize;
	inst->alg.cra_blkcipher.max_keysize =
	2 * alg->cra_cipher.cia_max_keysize;

	inst->alg.cra_ctxsize = sizeof(struct priv);

	inst->alg.cra_init = init_tfm;
	inst->alg.cra_exit = exit_tfm;

	inst->alg.cra_blkcipher.setkey = setkey;
	inst->alg.cra_blkcipher.encrypt = encrypt;
	inst->alg.cra_blkcipher.decrypt = decrypt;

	out_put_alg:
	crypto_mod_put(alg);
	return inst;
	}

	static void free(struct crypto_instance *inst)
	{
	crypto_drop_spawn(crypto_instance_ctx(inst));
	kfree(inst);
	}

	static struct crypto_template crypto_tmpl = {
	.name = "xts",
	.alloc = alloc,
	.free = free,
	.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");