/* * CBC: Cipher Block Chaining mode * * 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> struct crypto_cbc_ctx {	struct crypto_cipher *child;	void (*xor)(u8 *dst, const u8 *src, unsigned int bs);}; static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key,			     unsigned int keylen){	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent);	struct crypto_cipher *child = ctx->child;	int err; 	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);	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &				     CRYPTO_TFM_RES_MASK);	return err;} static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,				      struct blkcipher_walk *walk,				      struct crypto_cipher *tfm,				      void (*xor)(u8 *, const u8 *,						  unsigned int)){	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =		crypto_cipher_alg(tfm)->cia_encrypt;	int bsize = crypto_cipher_blocksize(tfm);	unsigned int nbytes = walk->nbytes;	u8 *src = walk->src.virt.addr;	u8 *dst = walk->dst.virt.addr;	u8 *iv = walk->iv; 	do {		xor(iv, src, bsize);		fn(crypto_cipher_tfm(tfm), dst, iv);		memcpy(iv, dst, bsize); 		src += bsize;		dst += bsize;	} while ((nbytes -= bsize) >= bsize); 	return nbytes;} static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,				      struct blkcipher_walk *walk,				      struct crypto_cipher *tfm,				      void (*xor)(u8 *, const u8 *,						  unsigned int)){	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =		crypto_cipher_alg(tfm)->cia_encrypt;	int bsize = crypto_cipher_blocksize(tfm);	unsigned int nbytes = walk->nbytes;	u8 *src = walk->src.virt.addr;	u8 *iv = walk->iv; 	do {		xor(src, iv, bsize);		fn(crypto_cipher_tfm(tfm), src, src);		iv = src; 		src += bsize;	} while ((nbytes -= bsize) >= bsize); 	memcpy(walk->iv, iv, bsize); 	return nbytes;} static int crypto_cbc_encrypt(struct blkcipher_desc *desc,			      struct scatterlist *dst, struct scatterlist *src,			      unsigned int nbytes){	struct blkcipher_walk walk;	struct crypto_blkcipher *tfm = desc->tfm;	struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);	struct crypto_cipher *child = ctx->child;	void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;	int err; 	blkcipher_walk_init(&walk, dst, src, nbytes);	err = blkcipher_walk_virt(desc, &walk); 	while ((nbytes = walk.nbytes)) {		if (walk.src.virt.addr == walk.dst.virt.addr)			nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child,							    xor);		else			nbytes = crypto_cbc_encrypt_segment(desc, &walk, child,							    xor);		err = blkcipher_walk_done(desc, &walk, nbytes);	} 	return err;} static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,				      struct blkcipher_walk *walk,				      struct crypto_cipher *tfm,				      void (*xor)(u8 *, const u8 *,						  unsigned int)){	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =		crypto_cipher_alg(tfm)->cia_decrypt;	int bsize = crypto_cipher_blocksize(tfm);	unsigned int nbytes = walk->nbytes;	u8 *src = walk->src.virt.addr;	u8 *dst = walk->dst.virt.addr;	u8 *iv = walk->iv; 	do {		fn(crypto_cipher_tfm(tfm), dst, src);		xor(dst, iv, bsize);		iv = src; 		src += bsize;		dst += bsize;	} while ((nbytes -= bsize) >= bsize); 	memcpy(walk->iv, iv, bsize); 	return nbytes;} static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,				      struct blkcipher_walk *walk,				      struct crypto_cipher *tfm,				      void (*xor)(u8 *, const u8 *,						  unsigned int)){	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =		crypto_cipher_alg(tfm)->cia_decrypt;	int bsize = crypto_cipher_blocksize(tfm);	unsigned long alignmask = crypto_cipher_alignmask(tfm);	unsigned int nbytes = walk->nbytes;	u8 *src = walk->src.virt.addr;	u8 stack[bsize + alignmask];	u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1); 	memcpy(first_iv, walk->iv, bsize); 	/* Start of the last block. */	src += nbytes - nbytes % bsize - bsize;	memcpy(walk->iv, src, bsize); 	for (;;) {		fn(crypto_cipher_tfm(tfm), src, src);		if ((nbytes -= bsize) < bsize)			break;		xor(src, src - bsize, bsize);		src -= bsize;	} 	xor(src, first_iv, bsize); 	return nbytes;} static int crypto_cbc_decrypt(struct blkcipher_desc *desc,			      struct scatterlist *dst, struct scatterlist *src,			      unsigned int nbytes){	struct blkcipher_walk walk;	struct crypto_blkcipher *tfm = desc->tfm;	struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);	struct crypto_cipher *child = ctx->child;	void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;	int err; 	blkcipher_walk_init(&walk, dst, src, nbytes);	err = blkcipher_walk_virt(desc, &walk); 	while ((nbytes = walk.nbytes)) {		if (walk.src.virt.addr == walk.dst.virt.addr)			nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child,							    xor);		else			nbytes = crypto_cbc_decrypt_segment(desc, &walk, child,							    xor);		err = blkcipher_walk_done(desc, &walk, nbytes);	} 	return err;} static void xor_byte(u8 *a, const u8 *b, unsigned int bs){	do {		*a++ ^= *b++;	} while (--bs);} static void xor_quad(u8 *dst, const u8 *src, unsigned int bs){	u32 *a = (u32 *)dst;	u32 *b = (u32 *)src; 	do {		*a++ ^= *b++;	} while ((bs -= 4));} static void xor_64(u8 *a, const u8 *b, unsigned int bs){	((u32 *)a)[0] ^= ((u32 *)b)[0];	((u32 *)a)[1] ^= ((u32 *)b)[1];} static void xor_128(u8 *a, const u8 *b, unsigned int bs){	((u32 *)a)[0] ^= ((u32 *)b)[0];	((u32 *)a)[1] ^= ((u32 *)b)[1];	((u32 *)a)[2] ^= ((u32 *)b)[2];	((u32 *)a)[3] ^= ((u32 *)b)[3];} static int crypto_cbc_init_tfm(struct crypto_tfm *tfm){	struct crypto_instance *inst = (void *)tfm->__crt_alg;	struct crypto_spawn *spawn = crypto_instance_ctx(inst);	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);	struct crypto_cipher *cipher; 	switch (crypto_tfm_alg_blocksize(tfm)) {	case 8:		ctx->xor = xor_64;		break; 	case 16:		ctx->xor = xor_128;		break; 	default:		if (crypto_tfm_alg_blocksize(tfm) % 4)			ctx->xor = xor_byte;		else			ctx->xor = xor_quad;	} 	cipher = crypto_spawn_cipher(spawn);	if (IS_ERR(cipher))		return PTR_ERR(cipher); 	ctx->child = cipher;	return 0;} static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm){	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);	crypto_free_cipher(ctx->child);} static struct crypto_instance *crypto_cbc_alloc(void *param, unsigned int len){	struct crypto_instance *inst;	struct crypto_alg *alg; 	alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,				  CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);	if (IS_ERR(alg))		return ERR_PTR(PTR_ERR(alg)); 	inst = crypto_alloc_instance("cbc", 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;	inst->alg.cra_alignmask = alg->cra_alignmask;	inst->alg.cra_type = &crypto_blkcipher_type; 	if (!(alg->cra_blocksize % 4))		inst->alg.cra_alignmask |= 3;	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;	inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;	inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; 	inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx); 	inst->alg.cra_init = crypto_cbc_init_tfm;	inst->alg.cra_exit = crypto_cbc_exit_tfm; 	inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;	inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;	inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt; out_put_alg:	crypto_mod_put(alg);	return inst;} static void crypto_cbc_free(struct crypto_instance *inst){	crypto_drop_spawn(crypto_instance_ctx(inst));	kfree(inst);} static struct crypto_template crypto_cbc_tmpl = {	.name = "cbc",	.alloc = crypto_cbc_alloc,	.free = crypto_cbc_free,	.module = THIS_MODULE,}; static int __init crypto_cbc_module_init(void){	return crypto_register_template(&crypto_cbc_tmpl);} static void __exit crypto_cbc_module_exit(void){	crypto_unregister_template(&crypto_cbc_tmpl);} module_init(crypto_cbc_module_init);module_exit(crypto_cbc_module_exit); MODULE_LICENSE("GPL");MODULE_DESCRIPTION("CBC block cipher algorithm");