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crypto: cbc - Export CBC implementation
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>
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Herbert Xu
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Nov 28, 2016
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,146 @@ | ||
| /* | ||
| * CBC: Cipher Block Chaining mode | ||
| * | ||
| * Copyright (c) 2016 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. | ||
| * | ||
| */ | ||
|
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| #ifndef _CRYPTO_CBC_H | ||
| #define _CRYPTO_CBC_H | ||
|
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| #include <crypto/internal/skcipher.h> | ||
| #include <linux/string.h> | ||
| #include <linux/types.h> | ||
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| static inline int crypto_cbc_encrypt_segment( | ||
| struct skcipher_walk *walk, struct crypto_skcipher *tfm, | ||
| void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) | ||
| { | ||
| unsigned int bsize = crypto_skcipher_blocksize(tfm); | ||
| unsigned int nbytes = walk->nbytes; | ||
| u8 *src = walk->src.virt.addr; | ||
| u8 *dst = walk->dst.virt.addr; | ||
| u8 *iv = walk->iv; | ||
|
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| do { | ||
| crypto_xor(iv, src, bsize); | ||
| fn(tfm, iv, dst); | ||
| memcpy(iv, dst, bsize); | ||
|
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| src += bsize; | ||
| dst += bsize; | ||
| } while ((nbytes -= bsize) >= bsize); | ||
|
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| return nbytes; | ||
| } | ||
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| static inline int crypto_cbc_encrypt_inplace( | ||
| struct skcipher_walk *walk, struct crypto_skcipher *tfm, | ||
| void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) | ||
| { | ||
| unsigned int bsize = crypto_skcipher_blocksize(tfm); | ||
| unsigned int nbytes = walk->nbytes; | ||
| u8 *src = walk->src.virt.addr; | ||
| u8 *iv = walk->iv; | ||
|
|
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| do { | ||
| crypto_xor(src, iv, bsize); | ||
| fn(tfm, src, src); | ||
| iv = src; | ||
|
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| src += bsize; | ||
| } while ((nbytes -= bsize) >= bsize); | ||
|
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| memcpy(walk->iv, iv, bsize); | ||
|
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| return nbytes; | ||
| } | ||
|
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| static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req, | ||
| void (*fn)(struct crypto_skcipher *, | ||
| const u8 *, u8 *)) | ||
| { | ||
| struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); | ||
| struct skcipher_walk walk; | ||
| int err; | ||
|
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| err = skcipher_walk_virt(&walk, req, false); | ||
|
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| while (walk.nbytes) { | ||
| if (walk.src.virt.addr == walk.dst.virt.addr) | ||
| err = crypto_cbc_encrypt_inplace(&walk, tfm, fn); | ||
| else | ||
| err = crypto_cbc_encrypt_segment(&walk, tfm, fn); | ||
| err = skcipher_walk_done(&walk, err); | ||
| } | ||
|
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| return err; | ||
| } | ||
|
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| static inline int crypto_cbc_decrypt_segment( | ||
| struct skcipher_walk *walk, struct crypto_skcipher *tfm, | ||
| void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) | ||
| { | ||
| unsigned int bsize = crypto_skcipher_blocksize(tfm); | ||
| unsigned int nbytes = walk->nbytes; | ||
| u8 *src = walk->src.virt.addr; | ||
| u8 *dst = walk->dst.virt.addr; | ||
| u8 *iv = walk->iv; | ||
|
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| do { | ||
| fn(tfm, src, dst); | ||
| crypto_xor(dst, iv, bsize); | ||
| iv = src; | ||
|
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| src += bsize; | ||
| dst += bsize; | ||
| } while ((nbytes -= bsize) >= bsize); | ||
|
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| memcpy(walk->iv, iv, bsize); | ||
|
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| return nbytes; | ||
| } | ||
|
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| static inline int crypto_cbc_decrypt_inplace( | ||
| struct skcipher_walk *walk, struct crypto_skcipher *tfm, | ||
| void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) | ||
| { | ||
| unsigned int bsize = crypto_skcipher_blocksize(tfm); | ||
| unsigned int nbytes = walk->nbytes; | ||
| u8 *src = walk->src.virt.addr; | ||
| u8 last_iv[bsize]; | ||
|
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| /* Start of the last block. */ | ||
| src += nbytes - (nbytes & (bsize - 1)) - bsize; | ||
| memcpy(last_iv, src, bsize); | ||
|
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| for (;;) { | ||
| fn(tfm, src, src); | ||
| if ((nbytes -= bsize) < bsize) | ||
| break; | ||
| crypto_xor(src, src - bsize, bsize); | ||
| src -= bsize; | ||
| } | ||
|
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| crypto_xor(src, walk->iv, bsize); | ||
| memcpy(walk->iv, last_iv, bsize); | ||
|
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| return nbytes; | ||
| } | ||
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| static inline int crypto_cbc_decrypt_blocks( | ||
| struct skcipher_walk *walk, struct crypto_skcipher *tfm, | ||
| void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) | ||
| { | ||
| if (walk->src.virt.addr == walk->dst.virt.addr) | ||
| return crypto_cbc_decrypt_inplace(walk, tfm, fn); | ||
| else | ||
| return crypto_cbc_decrypt_segment(walk, tfm, fn); | ||
| } | ||
|
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| #endif /* _CRYPTO_CBC_H */ |