cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ofb.c (2545B)

      1// SPDX-License-Identifier: GPL-2.0
      2
      3/*
      4 * OFB: Output FeedBack mode
      5 *
      6 * Copyright (C) 2018 ARM Limited or its affiliates.
      7 * All rights reserved.
      8 */
      9
     10#include <crypto/algapi.h>
     11#include <crypto/internal/cipher.h>
     12#include <crypto/internal/skcipher.h>
     13#include <linux/err.h>
     14#include <linux/init.h>
     15#include <linux/kernel.h>
     16#include <linux/module.h>
     17
     18static int crypto_ofb_crypt(struct skcipher_request *req)
     19{
     20	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
     21	struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
     22	const unsigned int bsize = crypto_cipher_blocksize(cipher);
     23	struct skcipher_walk walk;
     24	int err;
     25
     26	err = skcipher_walk_virt(&walk, req, false);
     27
     28	while (walk.nbytes >= bsize) {
     29		const u8 *src = walk.src.virt.addr;
     30		u8 *dst = walk.dst.virt.addr;
     31		u8 * const iv = walk.iv;
     32		unsigned int nbytes = walk.nbytes;
     33
     34		do {
     35			crypto_cipher_encrypt_one(cipher, iv, iv);
     36			crypto_xor_cpy(dst, src, iv, bsize);
     37			dst += bsize;
     38			src += bsize;
     39		} while ((nbytes -= bsize) >= bsize);
     40
     41		err = skcipher_walk_done(&walk, nbytes);
     42	}
     43
     44	if (walk.nbytes) {
     45		crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
     46		crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
     47			       walk.nbytes);
     48		err = skcipher_walk_done(&walk, 0);
     49	}
     50	return err;
     51}
     52
     53static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
     54{
     55	struct skcipher_instance *inst;
     56	struct crypto_alg *alg;
     57	int err;
     58
     59	inst = skcipher_alloc_instance_simple(tmpl, tb);
     60	if (IS_ERR(inst))
     61		return PTR_ERR(inst);
     62
     63	alg = skcipher_ialg_simple(inst);
     64
     65	/* OFB mode is a stream cipher. */
     66	inst->alg.base.cra_blocksize = 1;
     67
     68	/*
     69	 * To simplify the implementation, configure the skcipher walk to only
     70	 * give a partial block at the very end, never earlier.
     71	 */
     72	inst->alg.chunksize = alg->cra_blocksize;
     73
     74	inst->alg.encrypt = crypto_ofb_crypt;
     75	inst->alg.decrypt = crypto_ofb_crypt;
     76
     77	err = skcipher_register_instance(tmpl, inst);
     78	if (err)
     79		inst->free(inst);
     80
     81	return err;
     82}
     83
     84static struct crypto_template crypto_ofb_tmpl = {
     85	.name = "ofb",
     86	.create = crypto_ofb_create,
     87	.module = THIS_MODULE,
     88};
     89
     90static int __init crypto_ofb_module_init(void)
     91{
     92	return crypto_register_template(&crypto_ofb_tmpl);
     93}
     94
     95static void __exit crypto_ofb_module_exit(void)
     96{
     97	crypto_unregister_template(&crypto_ofb_tmpl);
     98}
     99
    100subsys_initcall(crypto_ofb_module_init);
    101module_exit(crypto_ofb_module_exit);
    102
    103MODULE_LICENSE("GPL");
    104MODULE_DESCRIPTION("OFB block cipher mode of operation");
    105MODULE_ALIAS_CRYPTO("ofb");
    106MODULE_IMPORT_NS(CRYPTO_INTERNAL);