// SPDX-License-Identifier: GPL-2.0-or-later/* * CBC: Cipher Block Chaining mode * * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au> */ #include <crypto/internal/skcipher.h>#include <linux/err.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/log2.h>#include <linux/module.h> static int crypto_cbc_encrypt_segment(struct crypto_lskcipher *tfm,				      const u8 *src, u8 *dst, unsigned nbytes,				      u8 *iv){	unsigned int bsize = crypto_lskcipher_blocksize(tfm); 	for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize) {		crypto_xor(iv, src, bsize);		crypto_lskcipher_encrypt(tfm, iv, dst, bsize, NULL);		memcpy(iv, dst, bsize);	} 	return nbytes;} static int crypto_cbc_encrypt_inplace(struct crypto_lskcipher *tfm,				      u8 *src, unsigned nbytes, u8 *oiv){	unsigned int bsize = crypto_lskcipher_blocksize(tfm);	u8 *iv = oiv; 	if (nbytes < bsize)		goto out; 	do {		crypto_xor(src, iv, bsize);		crypto_lskcipher_encrypt(tfm, src, src, bsize, NULL);		iv = src; 		src += bsize;	} while ((nbytes -= bsize) >= bsize); 	memcpy(oiv, iv, bsize); out:	return nbytes;} static int crypto_cbc_encrypt(struct crypto_lskcipher *tfm, const u8 *src,			      u8 *dst, unsigned len, u8 *iv, u32 flags){	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);	bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;	struct crypto_lskcipher *cipher = *ctx;	int rem; 	if (src == dst)		rem = crypto_cbc_encrypt_inplace(cipher, dst, len, iv);	else		rem = crypto_cbc_encrypt_segment(cipher, src, dst, len, iv); 	return rem && final ? -EINVAL : rem;} static int crypto_cbc_decrypt_segment(struct crypto_lskcipher *tfm,				      const u8 *src, u8 *dst, unsigned nbytes,				      u8 *oiv){	unsigned int bsize = crypto_lskcipher_blocksize(tfm);	const u8 *iv = oiv; 	if (nbytes < bsize)		goto out; 	do {		crypto_lskcipher_decrypt(tfm, src, dst, bsize, NULL);		crypto_xor(dst, iv, bsize);		iv = src; 		src += bsize;		dst += bsize;	} while ((nbytes -= bsize) >= bsize); 	memcpy(oiv, iv, bsize); out:	return nbytes;} static int crypto_cbc_decrypt_inplace(struct crypto_lskcipher *tfm,				      u8 *src, unsigned nbytes, u8 *iv){	unsigned int bsize = crypto_lskcipher_blocksize(tfm);	u8 last_iv[MAX_CIPHER_BLOCKSIZE]; 	if (nbytes < bsize)		goto out; 	/* Start of the last block. */	src += nbytes - (nbytes & (bsize - 1)) - bsize;	memcpy(last_iv, src, bsize); 	for (;;) {		crypto_lskcipher_decrypt(tfm, src, src, bsize, NULL);		if ((nbytes -= bsize) < bsize)			break;		crypto_xor(src, src - bsize, bsize);		src -= bsize;	} 	crypto_xor(src, iv, bsize);	memcpy(iv, last_iv, bsize); out:	return nbytes;} static int crypto_cbc_decrypt(struct crypto_lskcipher *tfm, const u8 *src,			      u8 *dst, unsigned len, u8 *iv, u32 flags){	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);	bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;	struct crypto_lskcipher *cipher = *ctx;	int rem; 	if (src == dst)		rem = crypto_cbc_decrypt_inplace(cipher, dst, len, iv);	else		rem = crypto_cbc_decrypt_segment(cipher, src, dst, len, iv); 	return rem && final ? -EINVAL : rem;} static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb){	struct lskcipher_instance *inst;	int err; 	inst = lskcipher_alloc_instance_simple(tmpl, tb);	if (IS_ERR(inst))		return PTR_ERR(inst); 	err = -EINVAL;	if (!is_power_of_2(inst->alg.co.base.cra_blocksize))		goto out_free_inst; 	if (inst->alg.co.statesize)		goto out_free_inst; 	inst->alg.encrypt = crypto_cbc_encrypt;	inst->alg.decrypt = crypto_cbc_decrypt; 	err = lskcipher_register_instance(tmpl, inst);	if (err) {out_free_inst:		inst->free(inst);	} 	return err;} static struct crypto_template crypto_cbc_tmpl = {	.name = "cbc",	.create = crypto_cbc_create,	.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 mode of operation");MODULE_ALIAS_CRYPTO("cbc");