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223 lines
5.2 KiB
223 lines
5.2 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* CBC: Cipher Block Chaining mode |
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* |
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* Copyright (c) 2006-2016 Herbert Xu <[email protected]> |
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*/ |
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#include <crypto/algapi.h> |
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#include <crypto/internal/cipher.h> |
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#include <crypto/internal/skcipher.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/log2.h> |
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#include <linux/module.h> |
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static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk, |
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struct crypto_skcipher *skcipher) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(skcipher); |
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *); |
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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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struct crypto_cipher *cipher; |
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struct crypto_tfm *tfm; |
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u8 *iv = walk->iv; |
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cipher = skcipher_cipher_simple(skcipher); |
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tfm = crypto_cipher_tfm(cipher); |
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fn = crypto_cipher_alg(cipher)->cia_encrypt; |
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do { |
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crypto_xor(iv, src, bsize); |
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fn(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 skcipher_walk *walk, |
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struct crypto_skcipher *skcipher) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(skcipher); |
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *); |
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unsigned int nbytes = walk->nbytes; |
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u8 *src = walk->src.virt.addr; |
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struct crypto_cipher *cipher; |
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struct crypto_tfm *tfm; |
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u8 *iv = walk->iv; |
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cipher = skcipher_cipher_simple(skcipher); |
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tfm = crypto_cipher_tfm(cipher); |
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fn = crypto_cipher_alg(cipher)->cia_encrypt; |
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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 int crypto_cbc_encrypt(struct skcipher_request *req) |
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{ |
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struct crypto_skcipher *skcipher = 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, skcipher); |
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else |
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err = crypto_cbc_encrypt_segment(&walk, skcipher); |
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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 int crypto_cbc_decrypt_segment(struct skcipher_walk *walk, |
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struct crypto_skcipher *skcipher) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(skcipher); |
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *); |
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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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struct crypto_cipher *cipher; |
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struct crypto_tfm *tfm; |
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u8 *iv = walk->iv; |
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cipher = skcipher_cipher_simple(skcipher); |
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tfm = crypto_cipher_tfm(cipher); |
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fn = crypto_cipher_alg(cipher)->cia_decrypt; |
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do { |
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fn(tfm, dst, src); |
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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 int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk, |
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struct crypto_skcipher *skcipher) |
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{ |
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unsigned int bsize = crypto_skcipher_blocksize(skcipher); |
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *); |
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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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struct crypto_cipher *cipher; |
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struct crypto_tfm *tfm; |
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cipher = skcipher_cipher_simple(skcipher); |
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tfm = crypto_cipher_tfm(cipher); |
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fn = crypto_cipher_alg(cipher)->cia_decrypt; |
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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 int crypto_cbc_decrypt(struct skcipher_request *req) |
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{ |
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struct crypto_skcipher *skcipher = 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_decrypt_inplace(&walk, skcipher); |
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else |
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err = crypto_cbc_decrypt_segment(&walk, skcipher); |
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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 int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) |
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{ |
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struct skcipher_instance *inst; |
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struct crypto_alg *alg; |
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int err; |
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inst = skcipher_alloc_instance_simple(tmpl, tb); |
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if (IS_ERR(inst)) |
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return PTR_ERR(inst); |
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alg = skcipher_ialg_simple(inst); |
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err = -EINVAL; |
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if (!is_power_of_2(alg->cra_blocksize)) |
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goto out_free_inst; |
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inst->alg.encrypt = crypto_cbc_encrypt; |
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inst->alg.decrypt = crypto_cbc_decrypt; |
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err = skcipher_register_instance(tmpl, inst); |
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if (err) { |
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out_free_inst: |
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inst->free(inst); |
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} |
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return err; |
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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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.create = crypto_cbc_create, |
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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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subsys_initcall(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 mode of operation"); |
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MODULE_ALIAS_CRYPTO("cbc");
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