127 lines
3.3 KiB
C
127 lines
3.3 KiB
C
/*
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* ChaCha20 256-bit cipher algorithm, RFC7539, arm64 NEON functions
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*
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* Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Based on:
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* ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
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*
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* Copyright (C) 2015 Martin Willi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <crypto/algapi.h>
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#include <crypto/chacha20.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <asm/hwcap.h>
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#include <asm/neon.h>
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asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);
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asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);
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static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes)
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{
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u8 buf[CHACHA20_BLOCK_SIZE];
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while (bytes >= CHACHA20_BLOCK_SIZE * 4) {
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chacha20_4block_xor_neon(state, dst, src);
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bytes -= CHACHA20_BLOCK_SIZE * 4;
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src += CHACHA20_BLOCK_SIZE * 4;
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dst += CHACHA20_BLOCK_SIZE * 4;
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state[12] += 4;
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}
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while (bytes >= CHACHA20_BLOCK_SIZE) {
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chacha20_block_xor_neon(state, dst, src);
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bytes -= CHACHA20_BLOCK_SIZE;
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src += CHACHA20_BLOCK_SIZE;
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dst += CHACHA20_BLOCK_SIZE;
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state[12]++;
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}
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if (bytes) {
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memcpy(buf, src, bytes);
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chacha20_block_xor_neon(state, buf, buf);
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memcpy(dst, buf, bytes);
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}
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}
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static int chacha20_neon(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 chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct skcipher_walk walk;
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u32 state[16];
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int err;
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if (req->cryptlen <= CHACHA20_BLOCK_SIZE)
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return crypto_chacha20_crypt(req);
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err = skcipher_walk_virt(&walk, req, true);
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crypto_chacha20_init(state, ctx, walk.iv);
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kernel_neon_begin();
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while (walk.nbytes > 0) {
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unsigned int 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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chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
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nbytes);
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err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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}
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kernel_neon_end();
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return err;
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}
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static struct skcipher_alg alg = {
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.base.cra_name = "chacha20",
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.base.cra_driver_name = "chacha20-neon",
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.base.cra_priority = 300,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha20_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA20_KEY_SIZE,
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.max_keysize = CHACHA20_KEY_SIZE,
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.ivsize = CHACHA20_IV_SIZE,
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.chunksize = CHACHA20_BLOCK_SIZE,
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.walksize = 4 * CHACHA20_BLOCK_SIZE,
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.setkey = crypto_chacha20_setkey,
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.encrypt = chacha20_neon,
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.decrypt = chacha20_neon,
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};
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static int __init chacha20_simd_mod_init(void)
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{
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if (!(elf_hwcap & HWCAP_ASIMD))
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return -ENODEV;
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return crypto_register_skcipher(&alg);
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}
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static void __exit chacha20_simd_mod_fini(void)
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{
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crypto_unregister_skcipher(&alg);
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}
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module_init(chacha20_simd_mod_init);
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module_exit(chacha20_simd_mod_fini);
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MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("chacha20");
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