This patch moves the core CBC implementation into a header file so that it can be reused by drivers implementing CBC. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>tirimbino
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/*
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* CBC: Cipher Block Chaining mode |
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* |
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* Copyright (c) 2016 Herbert Xu <herbert@gondor.apana.org.au> |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License as published by the Free |
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* Software Foundation; either version 2 of the License, or (at your option) |
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* any later version. |
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* |
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*/ |
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#ifndef _CRYPTO_CBC_H |
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#define _CRYPTO_CBC_H |
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#include <crypto/internal/skcipher.h> |
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#include <linux/string.h> |
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#include <linux/types.h> |
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static inline int crypto_cbc_encrypt_segment( |
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struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
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void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(tfm); |
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unsigned int nbytes = walk->nbytes; |
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u8 *src = walk->src.virt.addr; |
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u8 *dst = walk->dst.virt.addr; |
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u8 *iv = walk->iv; |
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do { |
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crypto_xor(iv, src, bsize); |
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fn(tfm, iv, dst); |
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memcpy(iv, dst, bsize); |
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src += bsize; |
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dst += bsize; |
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} while ((nbytes -= bsize) >= bsize); |
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return nbytes; |
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} |
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static inline int crypto_cbc_encrypt_inplace( |
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struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
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void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(tfm); |
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unsigned int nbytes = walk->nbytes; |
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u8 *src = walk->src.virt.addr; |
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u8 *iv = walk->iv; |
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do { |
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crypto_xor(src, iv, bsize); |
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fn(tfm, src, src); |
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iv = src; |
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src += bsize; |
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} while ((nbytes -= bsize) >= bsize); |
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memcpy(walk->iv, iv, bsize); |
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return nbytes; |
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} |
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static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req, |
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void (*fn)(struct crypto_skcipher *, |
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const u8 *, u8 *)) |
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{ |
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
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struct skcipher_walk walk; |
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int err; |
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err = skcipher_walk_virt(&walk, req, false); |
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while (walk.nbytes) { |
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if (walk.src.virt.addr == walk.dst.virt.addr) |
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err = crypto_cbc_encrypt_inplace(&walk, tfm, fn); |
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else |
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err = crypto_cbc_encrypt_segment(&walk, tfm, fn); |
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err = skcipher_walk_done(&walk, err); |
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} |
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return err; |
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} |
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static inline int crypto_cbc_decrypt_segment( |
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struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
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void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(tfm); |
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unsigned int nbytes = walk->nbytes; |
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u8 *src = walk->src.virt.addr; |
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u8 *dst = walk->dst.virt.addr; |
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u8 *iv = walk->iv; |
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do { |
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fn(tfm, src, dst); |
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crypto_xor(dst, iv, bsize); |
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iv = src; |
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src += bsize; |
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dst += bsize; |
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} while ((nbytes -= bsize) >= bsize); |
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memcpy(walk->iv, iv, bsize); |
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return nbytes; |
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} |
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static inline int crypto_cbc_decrypt_inplace( |
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struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
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void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(tfm); |
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unsigned int nbytes = walk->nbytes; |
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u8 *src = walk->src.virt.addr; |
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u8 last_iv[bsize]; |
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/* Start of the last block. */ |
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src += nbytes - (nbytes & (bsize - 1)) - bsize; |
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memcpy(last_iv, src, bsize); |
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for (;;) { |
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fn(tfm, src, src); |
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if ((nbytes -= bsize) < bsize) |
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break; |
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crypto_xor(src, src - bsize, bsize); |
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src -= bsize; |
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} |
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crypto_xor(src, walk->iv, bsize); |
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memcpy(walk->iv, last_iv, bsize); |
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return nbytes; |
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} |
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static inline int crypto_cbc_decrypt_blocks( |
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struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
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void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
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{ |
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if (walk->src.virt.addr == walk->dst.virt.addr) |
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return crypto_cbc_decrypt_inplace(walk, tfm, fn); |
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else |
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return crypto_cbc_decrypt_segment(walk, tfm, fn); |
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} |
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#endif /* _CRYPTO_CBC_H */ |
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