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d73d67fbcb
In the quest to remove all stack VLA usage from the kernel[1], this uses the upper bounds on blocksize. Since this is always a cipher blocksize, use the existing cipher max blocksize. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
146 lines
3.5 KiB
C
146 lines
3.5 KiB
C
/*
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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[MAX_CIPHER_BLOCKSIZE];
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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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