diff options
Diffstat (limited to 'crypto/pcbc.c')
| -rw-r--r-- | crypto/pcbc.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/crypto/pcbc.c b/crypto/pcbc.c new file mode 100644 index 000000000..ae921fb74 --- /dev/null +++ b/crypto/pcbc.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * PCBC: Propagating Cipher Block Chaining mode + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * Derived from cbc.c + * - Copyright (c) 2006 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/module.h> + +static int crypto_pcbc_encrypt_segment(struct skcipher_request *req, + struct skcipher_walk *walk, + struct crypto_cipher *tfm) +{ + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 * const iv = walk->iv; + + do { + crypto_xor(iv, src, bsize); + crypto_cipher_encrypt_one(tfm, dst, iv); + crypto_xor_cpy(iv, dst, src, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req, + struct skcipher_walk *walk, + struct crypto_cipher *tfm) +{ + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 * const iv = walk->iv; + u8 tmpbuf[MAX_CIPHER_BLOCKSIZE]; + + do { + memcpy(tmpbuf, src, bsize); + crypto_xor(iv, src, bsize); + crypto_cipher_encrypt_one(tfm, src, iv); + crypto_xor_cpy(iv, tmpbuf, src, bsize); + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_pcbc_encrypt(struct skcipher_request *req) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); + struct skcipher_walk walk; + unsigned int nbytes; + int err; + + err = skcipher_walk_virt(&walk, req, false); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_pcbc_encrypt_inplace(req, &walk, + cipher); + else + nbytes = crypto_pcbc_encrypt_segment(req, &walk, + cipher); + err = skcipher_walk_done(&walk, nbytes); + } + + return err; +} + +static int crypto_pcbc_decrypt_segment(struct skcipher_request *req, + struct skcipher_walk *walk, + struct crypto_cipher *tfm) +{ + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 * const iv = walk->iv; + + do { + crypto_cipher_decrypt_one(tfm, dst, src); + crypto_xor(dst, iv, bsize); + crypto_xor_cpy(iv, dst, src, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req, + struct skcipher_walk *walk, + struct crypto_cipher *tfm) +{ + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 * const iv = walk->iv; + u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32)); + + do { + memcpy(tmpbuf, src, bsize); + crypto_cipher_decrypt_one(tfm, src, src); + crypto_xor(src, iv, bsize); + crypto_xor_cpy(iv, src, tmpbuf, bsize); + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_pcbc_decrypt(struct skcipher_request *req) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); + struct skcipher_walk walk; + unsigned int nbytes; + int err; + + err = skcipher_walk_virt(&walk, req, false); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_pcbc_decrypt_inplace(req, &walk, + cipher); + else + nbytes = crypto_pcbc_decrypt_segment(req, &walk, + cipher); + err = skcipher_walk_done(&walk, nbytes); + } + + return err; +} + +static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct skcipher_instance *inst; + int err; + + inst = skcipher_alloc_instance_simple(tmpl, tb); + if (IS_ERR(inst)) + return PTR_ERR(inst); + + inst->alg.encrypt = crypto_pcbc_encrypt; + inst->alg.decrypt = crypto_pcbc_decrypt; + + err = skcipher_register_instance(tmpl, inst); + if (err) + inst->free(inst); + + return err; +} + +static struct crypto_template crypto_pcbc_tmpl = { + .name = "pcbc", + .create = crypto_pcbc_create, + .module = THIS_MODULE, +}; + +static int __init crypto_pcbc_module_init(void) +{ + return crypto_register_template(&crypto_pcbc_tmpl); +} + +static void __exit crypto_pcbc_module_exit(void) +{ + crypto_unregister_template(&crypto_pcbc_tmpl); +} + +subsys_initcall(crypto_pcbc_module_init); +module_exit(crypto_pcbc_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("PCBC block cipher mode of operation"); +MODULE_ALIAS_CRYPTO("pcbc"); |