346 lines
8.6 KiB
C
346 lines
8.6 KiB
C
/*
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* CBC: Cipher Block Chaining mode
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*
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* Copyright (c) 2006 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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#include <crypto/algapi.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/slab.h>
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struct crypto_cbc_ctx {
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struct crypto_cipher *child;
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void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
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};
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static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key,
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unsigned int keylen)
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{
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struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent);
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struct crypto_cipher *child = ctx->child;
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int err;
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crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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err = crypto_cipher_setkey(child, key, keylen);
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crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
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CRYPTO_TFM_RES_MASK);
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return err;
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}
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static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,
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struct blkcipher_walk *walk,
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struct crypto_cipher *tfm,
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void (*xor)(u8 *, const u8 *,
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unsigned int))
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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int bsize = crypto_cipher_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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xor(iv, src, bsize);
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fn(crypto_cipher_tfm(tfm), dst, iv);
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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 int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
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struct blkcipher_walk *walk,
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struct crypto_cipher *tfm,
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void (*xor)(u8 *, const u8 *,
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unsigned int))
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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int bsize = crypto_cipher_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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xor(src, iv, bsize);
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fn(crypto_cipher_tfm(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 int crypto_cbc_encrypt(struct blkcipher_desc *desc,
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struct scatterlist *dst, struct scatterlist *src,
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unsigned int nbytes)
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{
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struct blkcipher_walk walk;
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struct crypto_blkcipher *tfm = desc->tfm;
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struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
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struct crypto_cipher *child = ctx->child;
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void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
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int err;
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blkcipher_walk_init(&walk, dst, src, nbytes);
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err = blkcipher_walk_virt(desc, &walk);
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while ((nbytes = walk.nbytes)) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child,
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xor);
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else
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nbytes = crypto_cbc_encrypt_segment(desc, &walk, child,
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xor);
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err = blkcipher_walk_done(desc, &walk, nbytes);
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}
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return err;
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}
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static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
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struct blkcipher_walk *walk,
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struct crypto_cipher *tfm,
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void (*xor)(u8 *, const u8 *,
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unsigned int))
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_decrypt;
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int bsize = crypto_cipher_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(crypto_cipher_tfm(tfm), dst, src);
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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 int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
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struct blkcipher_walk *walk,
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struct crypto_cipher *tfm,
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void (*xor)(u8 *, const u8 *,
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unsigned int))
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_decrypt;
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int bsize = crypto_cipher_blocksize(tfm);
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unsigned long alignmask = crypto_cipher_alignmask(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 stack[bsize + alignmask];
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u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
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memcpy(first_iv, walk->iv, bsize);
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/* Start of the last block. */
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src += nbytes - nbytes % bsize - bsize;
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memcpy(walk->iv, src, bsize);
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for (;;) {
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fn(crypto_cipher_tfm(tfm), src, src);
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if ((nbytes -= bsize) < bsize)
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break;
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xor(src, src - bsize, bsize);
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src -= bsize;
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}
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xor(src, first_iv, bsize);
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return nbytes;
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}
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static int crypto_cbc_decrypt(struct blkcipher_desc *desc,
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struct scatterlist *dst, struct scatterlist *src,
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unsigned int nbytes)
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{
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struct blkcipher_walk walk;
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struct crypto_blkcipher *tfm = desc->tfm;
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struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
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struct crypto_cipher *child = ctx->child;
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void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
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int err;
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blkcipher_walk_init(&walk, dst, src, nbytes);
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err = blkcipher_walk_virt(desc, &walk);
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while ((nbytes = walk.nbytes)) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child,
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xor);
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else
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nbytes = crypto_cbc_decrypt_segment(desc, &walk, child,
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xor);
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err = blkcipher_walk_done(desc, &walk, nbytes);
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}
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return err;
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}
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static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
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{
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do {
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*a++ ^= *b++;
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} while (--bs);
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}
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static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
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{
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u32 *a = (u32 *)dst;
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u32 *b = (u32 *)src;
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do {
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*a++ ^= *b++;
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} while ((bs -= 4));
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}
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static void xor_64(u8 *a, const u8 *b, unsigned int bs)
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{
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((u32 *)a)[0] ^= ((u32 *)b)[0];
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((u32 *)a)[1] ^= ((u32 *)b)[1];
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}
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static void xor_128(u8 *a, const u8 *b, unsigned int bs)
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{
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((u32 *)a)[0] ^= ((u32 *)b)[0];
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((u32 *)a)[1] ^= ((u32 *)b)[1];
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((u32 *)a)[2] ^= ((u32 *)b)[2];
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((u32 *)a)[3] ^= ((u32 *)b)[3];
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}
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static int crypto_cbc_init_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_instance *inst = (void *)tfm->__crt_alg;
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struct crypto_spawn *spawn = crypto_instance_ctx(inst);
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struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
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struct crypto_cipher *cipher;
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switch (crypto_tfm_alg_blocksize(tfm)) {
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case 8:
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ctx->xor = xor_64;
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break;
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case 16:
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ctx->xor = xor_128;
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break;
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default:
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if (crypto_tfm_alg_blocksize(tfm) % 4)
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ctx->xor = xor_byte;
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else
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ctx->xor = xor_quad;
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}
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cipher = crypto_spawn_cipher(spawn);
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if (IS_ERR(cipher))
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return PTR_ERR(cipher);
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ctx->child = cipher;
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return 0;
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}
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static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
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crypto_free_cipher(ctx->child);
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}
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static struct crypto_instance *crypto_cbc_alloc(void *param, unsigned int len)
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{
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struct crypto_instance *inst;
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struct crypto_alg *alg;
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alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
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if (IS_ERR(alg))
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return ERR_PTR(PTR_ERR(alg));
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inst = crypto_alloc_instance("cbc", alg);
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if (IS_ERR(inst))
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goto out_put_alg;
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inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
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inst->alg.cra_priority = alg->cra_priority;
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inst->alg.cra_blocksize = alg->cra_blocksize;
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inst->alg.cra_alignmask = alg->cra_alignmask;
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inst->alg.cra_type = &crypto_blkcipher_type;
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if (!(alg->cra_blocksize % 4))
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inst->alg.cra_alignmask |= 3;
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inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
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inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
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inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
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inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
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inst->alg.cra_init = crypto_cbc_init_tfm;
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inst->alg.cra_exit = crypto_cbc_exit_tfm;
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inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;
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inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;
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inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt;
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out_put_alg:
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crypto_mod_put(alg);
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return inst;
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}
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static void crypto_cbc_free(struct crypto_instance *inst)
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{
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crypto_drop_spawn(crypto_instance_ctx(inst));
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kfree(inst);
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}
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static struct crypto_template crypto_cbc_tmpl = {
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.name = "cbc",
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.alloc = crypto_cbc_alloc,
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.free = crypto_cbc_free,
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.module = THIS_MODULE,
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};
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static int __init crypto_cbc_module_init(void)
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{
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return crypto_register_template(&crypto_cbc_tmpl);
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}
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static void __exit crypto_cbc_module_exit(void)
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{
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crypto_unregister_template(&crypto_cbc_tmpl);
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}
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module_init(crypto_cbc_module_init);
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module_exit(crypto_cbc_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CBC block cipher algorithm");
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