diff options
Diffstat (limited to 'crypto/cbc.c')
| -rw-r--r-- | crypto/cbc.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/crypto/cbc.c b/crypto/cbc.c new file mode 100644 index 000000000..0d9509dff --- /dev/null +++ b/crypto/cbc.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * CBC: Cipher Block Chaining mode + * + * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au> + */ + +#include <crypto/algapi.h> +#include <crypto/internal/skcipher.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/log2.h> +#include <linux/module.h> + +static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk, + struct crypto_skcipher *skcipher) +{ + unsigned int bsize = crypto_skcipher_blocksize(skcipher); + void (*fn)(struct crypto_tfm *, u8 *, const u8 *); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + struct crypto_cipher *cipher; + struct crypto_tfm *tfm; + u8 *iv = walk->iv; + + cipher = skcipher_cipher_simple(skcipher); + tfm = crypto_cipher_tfm(cipher); + fn = crypto_cipher_alg(cipher)->cia_encrypt; + + do { + crypto_xor(iv, src, bsize); + fn(tfm, dst, iv); + memcpy(iv, dst, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk, + struct crypto_skcipher *skcipher) +{ + unsigned int bsize = crypto_skcipher_blocksize(skcipher); + void (*fn)(struct crypto_tfm *, u8 *, const u8 *); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + struct crypto_cipher *cipher; + struct crypto_tfm *tfm; + u8 *iv = walk->iv; + + cipher = skcipher_cipher_simple(skcipher); + tfm = crypto_cipher_tfm(cipher); + fn = crypto_cipher_alg(cipher)->cia_encrypt; + + do { + crypto_xor(src, iv, bsize); + fn(tfm, src, src); + iv = src; + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt(struct skcipher_request *req) +{ + struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req); + struct skcipher_walk walk; + int err; + + err = skcipher_walk_virt(&walk, req, false); + + while (walk.nbytes) { + if (walk.src.virt.addr == walk.dst.virt.addr) + err = crypto_cbc_encrypt_inplace(&walk, skcipher); + else + err = crypto_cbc_encrypt_segment(&walk, skcipher); + err = skcipher_walk_done(&walk, err); + } + + return err; +} + +static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk, + struct crypto_skcipher *skcipher) +{ + unsigned int bsize = crypto_skcipher_blocksize(skcipher); + void (*fn)(struct crypto_tfm *, u8 *, const u8 *); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + struct crypto_cipher *cipher; + struct crypto_tfm *tfm; + u8 *iv = walk->iv; + + cipher = skcipher_cipher_simple(skcipher); + tfm = crypto_cipher_tfm(cipher); + fn = crypto_cipher_alg(cipher)->cia_decrypt; + + do { + fn(tfm, dst, src); + crypto_xor(dst, iv, bsize); + iv = src; + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk, + struct crypto_skcipher *skcipher) +{ + unsigned int bsize = crypto_skcipher_blocksize(skcipher); + void (*fn)(struct crypto_tfm *, u8 *, const u8 *); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 last_iv[MAX_CIPHER_BLOCKSIZE]; + struct crypto_cipher *cipher; + struct crypto_tfm *tfm; + + cipher = skcipher_cipher_simple(skcipher); + tfm = crypto_cipher_tfm(cipher); + fn = crypto_cipher_alg(cipher)->cia_decrypt; + + /* Start of the last block. */ + src += nbytes - (nbytes & (bsize - 1)) - bsize; + memcpy(last_iv, src, bsize); + + for (;;) { + fn(tfm, src, src); + if ((nbytes -= bsize) < bsize) + break; + crypto_xor(src, src - bsize, bsize); + src -= bsize; + } + + crypto_xor(src, walk->iv, bsize); + memcpy(walk->iv, last_iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt(struct skcipher_request *req) +{ + struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req); + struct skcipher_walk walk; + int err; + + err = skcipher_walk_virt(&walk, req, false); + + while (walk.nbytes) { + if (walk.src.virt.addr == walk.dst.virt.addr) + err = crypto_cbc_decrypt_inplace(&walk, skcipher); + else + err = crypto_cbc_decrypt_segment(&walk, skcipher); + err = skcipher_walk_done(&walk, err); + } + + return err; +} + +static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct skcipher_instance *inst; + struct crypto_alg *alg; + int err; + + inst = skcipher_alloc_instance_simple(tmpl, tb); + if (IS_ERR(inst)) + return PTR_ERR(inst); + + alg = skcipher_ialg_simple(inst); + + err = -EINVAL; + if (!is_power_of_2(alg->cra_blocksize)) + goto out_free_inst; + + inst->alg.encrypt = crypto_cbc_encrypt; + inst->alg.decrypt = crypto_cbc_decrypt; + + err = skcipher_register_instance(tmpl, inst); + if (err) { +out_free_inst: + inst->free(inst); + } + + return err; +} + +static struct crypto_template crypto_cbc_tmpl = { + .name = "cbc", + .create = crypto_cbc_create, + .module = THIS_MODULE, +}; + +static int __init crypto_cbc_module_init(void) +{ + return crypto_register_template(&crypto_cbc_tmpl); +} + +static void __exit crypto_cbc_module_exit(void) +{ + crypto_unregister_template(&crypto_cbc_tmpl); +} + +subsys_initcall(crypto_cbc_module_init); +module_exit(crypto_cbc_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("CBC block cipher mode of operation"); +MODULE_ALIAS_CRYPTO("cbc"); |