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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chacha-glue.c (3505B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * s390 ChaCha stream cipher.
      4 *
      5 * Copyright IBM Corp. 2021
      6 */
      7
      8#define KMSG_COMPONENT "chacha_s390"
      9#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
     10
     11#include <crypto/internal/chacha.h>
     12#include <crypto/internal/skcipher.h>
     13#include <crypto/algapi.h>
     14#include <linux/cpufeature.h>
     15#include <linux/kernel.h>
     16#include <linux/module.h>
     17#include <linux/sizes.h>
     18#include <asm/fpu/api.h>
     19#include "chacha-s390.h"
     20
     21static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
     22				unsigned int nbytes, const u32 *key,
     23				u32 *counter)
     24{
     25	struct kernel_fpu vxstate;
     26
     27	kernel_fpu_begin(&vxstate, KERNEL_VXR);
     28	chacha20_vx(dst, src, nbytes, key, counter);
     29	kernel_fpu_end(&vxstate, KERNEL_VXR);
     30
     31	*counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
     32}
     33
     34static int chacha20_s390(struct skcipher_request *req)
     35{
     36	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
     37	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
     38	u32 state[CHACHA_STATE_WORDS] __aligned(16);
     39	struct skcipher_walk walk;
     40	unsigned int nbytes;
     41	int rc;
     42
     43	rc = skcipher_walk_virt(&walk, req, false);
     44	chacha_init_generic(state, ctx->key, req->iv);
     45
     46	while (walk.nbytes > 0) {
     47		nbytes = walk.nbytes;
     48		if (nbytes < walk.total)
     49			nbytes = round_down(nbytes, walk.stride);
     50
     51		if (nbytes <= CHACHA_BLOCK_SIZE) {
     52			chacha_crypt_generic(state, walk.dst.virt.addr,
     53					     walk.src.virt.addr, nbytes,
     54					     ctx->nrounds);
     55		} else {
     56			chacha20_crypt_s390(state, walk.dst.virt.addr,
     57					    walk.src.virt.addr, nbytes,
     58					    &state[4], &state[12]);
     59		}
     60		rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
     61	}
     62	return rc;
     63}
     64
     65void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
     66{
     67	/* TODO: implement hchacha_block_arch() in assembly */
     68	hchacha_block_generic(state, stream, nrounds);
     69}
     70EXPORT_SYMBOL(hchacha_block_arch);
     71
     72void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
     73{
     74	chacha_init_generic(state, key, iv);
     75}
     76EXPORT_SYMBOL(chacha_init_arch);
     77
     78void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
     79		       unsigned int bytes, int nrounds)
     80{
     81	/* s390 chacha20 implementation has 20 rounds hard-coded,
     82	 * it cannot handle a block of data or less, but otherwise
     83	 * it can handle data of arbitrary size
     84	 */
     85	if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20)
     86		chacha_crypt_generic(state, dst, src, bytes, nrounds);
     87	else
     88		chacha20_crypt_s390(state, dst, src, bytes,
     89				    &state[4], &state[12]);
     90}
     91EXPORT_SYMBOL(chacha_crypt_arch);
     92
     93static struct skcipher_alg chacha_algs[] = {
     94	{
     95		.base.cra_name		= "chacha20",
     96		.base.cra_driver_name	= "chacha20-s390",
     97		.base.cra_priority	= 900,
     98		.base.cra_blocksize	= 1,
     99		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
    100		.base.cra_module	= THIS_MODULE,
    101
    102		.min_keysize		= CHACHA_KEY_SIZE,
    103		.max_keysize		= CHACHA_KEY_SIZE,
    104		.ivsize			= CHACHA_IV_SIZE,
    105		.chunksize		= CHACHA_BLOCK_SIZE,
    106		.setkey			= chacha20_setkey,
    107		.encrypt		= chacha20_s390,
    108		.decrypt		= chacha20_s390,
    109	}
    110};
    111
    112static int __init chacha_mod_init(void)
    113{
    114	return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
    115		crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
    116}
    117
    118static void __exit chacha_mod_fini(void)
    119{
    120	if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
    121		crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
    122}
    123
    124module_cpu_feature_match(VXRS, chacha_mod_init);
    125module_exit(chacha_mod_fini);
    126
    127MODULE_DESCRIPTION("ChaCha20 stream cipher");
    128MODULE_LICENSE("GPL v2");
    129
    130MODULE_ALIAS_CRYPTO("chacha20");