131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* s390 ChaCha stream cipher.
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*
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* Copyright IBM Corp. 2021
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*/
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#define KMSG_COMPONENT "chacha_s390"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <crypto/internal/chacha.h>
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#include <crypto/internal/skcipher.h>
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#include <crypto/algapi.h>
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#include <linux/cpufeature.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sizes.h>
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#include <asm/fpu/api.h>
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#include "chacha-s390.h"
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static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
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unsigned int nbytes, const u32 *key,
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u32 *counter)
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{
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struct kernel_fpu vxstate;
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kernel_fpu_begin(&vxstate, KERNEL_VXR);
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chacha20_vx(dst, src, nbytes, key, counter);
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kernel_fpu_end(&vxstate, KERNEL_VXR);
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*counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
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}
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static int chacha20_s390(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
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u32 state[CHACHA_STATE_WORDS] __aligned(16);
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struct skcipher_walk walk;
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unsigned int nbytes;
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int rc;
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rc = skcipher_walk_virt(&walk, req, false);
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chacha_init_generic(state, ctx->key, req->iv);
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while (walk.nbytes > 0) {
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nbytes = walk.nbytes;
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if (nbytes < walk.total)
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nbytes = round_down(nbytes, walk.stride);
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if (nbytes <= CHACHA_BLOCK_SIZE) {
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chacha_crypt_generic(state, walk.dst.virt.addr,
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walk.src.virt.addr, nbytes,
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ctx->nrounds);
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} else {
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chacha20_crypt_s390(state, walk.dst.virt.addr,
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walk.src.virt.addr, nbytes,
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&state[4], &state[12]);
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}
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rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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}
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return rc;
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}
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void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
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{
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/* TODO: implement hchacha_block_arch() in assembly */
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hchacha_block_generic(state, stream, nrounds);
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}
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EXPORT_SYMBOL(hchacha_block_arch);
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void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
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{
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chacha_init_generic(state, key, iv);
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}
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EXPORT_SYMBOL(chacha_init_arch);
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void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds)
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{
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/* s390 chacha20 implementation has 20 rounds hard-coded,
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* it cannot handle a block of data or less, but otherwise
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* it can handle data of arbitrary size
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*/
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if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !MACHINE_HAS_VX)
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chacha_crypt_generic(state, dst, src, bytes, nrounds);
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else
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chacha20_crypt_s390(state, dst, src, bytes,
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&state[4], &state[12]);
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}
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EXPORT_SYMBOL(chacha_crypt_arch);
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static struct skcipher_alg chacha_algs[] = {
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{
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.base.cra_name = "chacha20",
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.base.cra_driver_name = "chacha20-s390",
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.base.cra_priority = 900,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA_KEY_SIZE,
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.max_keysize = CHACHA_KEY_SIZE,
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.ivsize = CHACHA_IV_SIZE,
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.chunksize = CHACHA_BLOCK_SIZE,
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.setkey = chacha20_setkey,
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.encrypt = chacha20_s390,
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.decrypt = chacha20_s390,
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}
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};
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static int __init chacha_mod_init(void)
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{
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return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
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crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
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}
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static void __exit chacha_mod_fini(void)
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{
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if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
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crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
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}
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module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
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module_exit(chacha_mod_fini);
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MODULE_DESCRIPTION("ChaCha20 stream cipher");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("chacha20");
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