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- // 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 ([email protected])
- *
- * Derived from cbc.c
- * - Copyright (c) 2006 Herbert Xu <[email protected]>
- */
- #include <crypto/algapi.h>
- #include <crypto/internal/cipher.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");
- MODULE_IMPORT_NS(CRYPTO_INTERNAL);
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