124 lines
3.2 KiB
C
124 lines
3.2 KiB
C
/*
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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 <linux/crypto.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <asm/fpu/api.h>
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#include <asm/simd.h>
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#define CHACHA20_STATE_ALIGN 16
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asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
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static void chacha20_dosimd(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) {
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chacha20_block_xor_ssse3(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_ssse3(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_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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u32 *state, state_buf[16 + (CHACHA20_STATE_ALIGN / sizeof(u32)) - 1];
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struct blkcipher_walk walk;
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int err;
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if (!may_use_simd())
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return crypto_chacha20_crypt(desc, dst, src, nbytes);
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state = (u32 *)roundup((uintptr_t)state_buf, CHACHA20_STATE_ALIGN);
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blkcipher_walk_init(&walk, dst, src, nbytes);
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err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
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crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
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kernel_fpu_begin();
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while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
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chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
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rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
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err = blkcipher_walk_done(desc, &walk,
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walk.nbytes % CHACHA20_BLOCK_SIZE);
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}
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if (walk.nbytes) {
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chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
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walk.nbytes);
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err = blkcipher_walk_done(desc, &walk, 0);
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}
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kernel_fpu_end();
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return err;
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}
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static struct crypto_alg alg = {
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.cra_name = "chacha20",
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.cra_driver_name = "chacha20-simd",
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.cra_priority = 300,
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.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
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.cra_blocksize = 1,
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.cra_type = &crypto_blkcipher_type,
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.cra_ctxsize = sizeof(struct chacha20_ctx),
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.cra_alignmask = sizeof(u32) - 1,
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.cra_module = THIS_MODULE,
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.cra_u = {
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.blkcipher = {
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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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.geniv = "seqiv",
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.setkey = crypto_chacha20_setkey,
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.encrypt = chacha20_simd,
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.decrypt = chacha20_simd,
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},
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},
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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 (!cpu_has_ssse3)
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return -ENODEV;
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return crypto_register_alg(&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_alg(&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_LICENSE("GPL");
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MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
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MODULE_DESCRIPTION("chacha20 cipher algorithm, SIMD accelerated");
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MODULE_ALIAS_CRYPTO("chacha20");
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MODULE_ALIAS_CRYPTO("chacha20-simd");
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