/*
* aes-ce-cipher.c - core AES cipher using ARMv8 Crypto Extensions
*
* Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <asm/neon.h>
#include <crypto/aes.h>
#include <linux/cpufeature.h>
#include <linux/crypto.h>
#include <linux/module.h>
#include "aes-ce-setkey.h"
MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
struct aes_block {
u8 b[AES_BLOCK_SIZE];
};
static int num_rounds(struct crypto_aes_ctx *ctx)
{
/*
* # of rounds specified by AES:
* 128 bit key 10 rounds
* 192 bit key 12 rounds
* 256 bit key 14 rounds
* => n byte key => 6 + (n/4) rounds
*/
return 6 + ctx->key_length / 4;
}
static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
{
struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
struct aes_block *out = (struct aes_block *)dst;
struct aes_block const *in = (struct aes_block *)src;
void *dummy0;
int dummy1;
kernel_neon_begin_partial(4);
__asm__(" ld1 {v0.16b}, %[in] ;"
" ld1 {v1.2d}, [%[key]], #16 ;"
" cmp %w[rounds], #10 ;"
" bmi 0f ;"
" bne 3f ;"
" mov v3.16b, v1.16b ;"
" b 2f ;"
"0: mov v2.16b, v1.16b ;"
" ld1 {v3.2d}, [%[key]], #16 ;"
"1: aese v0.16b, v2.16b ;"
" aesmc v0.16b, v0.16b ;"
"2: ld1 {v1.2d}, [%[key]], #16 ;"
" aese v0.16b, v3.16b ;"
" aesmc v0.16b, v0.16b ;"
"3: ld1 {v2.2d}, [%[key]], #16 ;"
" subs %w[rounds], %w[rounds], #3 ;"
" aese v0.16b, v1.16b ;"
" aesmc v0.16b, v0.16b ;"
" ld1 {v3.2d}, [%[key]], #16 ;"
" bpl 1b ;"
" aese v0.16b, v2.16b ;"
" eor v0.16b, v0.16b, v3.16b ;"
" st1 {v0.16b}, %[out] ;"
: [out] "=Q"(*out),
[key] "=r"(dummy0),
[rounds] "=r"(dummy1)
: [in] "Q"(*in),
"1"(ctx->key_enc),
"2"(num_rounds(ctx) - 2)
: "cc");
kernel_neon_end();
}
static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
{
struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
struct aes_block *out = (struct aes_block *)dst;
struct aes_block const *in = (struct aes_block *)src;
void *dummy0;
int dummy1;
kernel_neon_begin_partial(4);
__asm__(" ld1 {v0.16b}, %[in] ;"
" ld1 {v1.2d}, [%[key]], #16 ;"
" cmp %w[rounds], #10 ;"
" bmi 0f ;"
" bne 3f ;"
" mov v3.16b, v1.16b ;"
" b 2f ;"
"0: mov v2.16b, v1.16b ;"
" ld1 {v3.2d}, [%[key]], #16 ;"
"1: aesd v0.16b, v2.16b ;"
" aesimc v0.16b, v0.16b ;"
"2: ld1 {v1.2d}, [%[key]], #16 ;"
" aesd v0.16b, v3.16b ;"
" aesimc v0.16b, v0.16b ;"
"3: ld1 {v2.2d}, [%[key]], #16 ;"
" subs %w[rounds], %w[rounds], #3 ;"
" aesd v0.16b, v1.16b ;"
" aesimc v0.16b, v0.16b ;"
" ld1 {v3.2d}, [%[key]], #16 ;"
" bpl 1b ;"
" aesd v0.16b, v2.16b ;"
" eor v0.16b, v0.16b, v3.16b ;"
" st1 {v0.16b}, %[out] ;"
: [out] "=Q"(*out),
[key] "=r"(dummy0),
[rounds] "=r"(dummy1)
: [in] "Q"(*in),
"1"(ctx->key_dec),
"2"(num_rounds(ctx) - 2)
: "cc");
kernel_neon_end();
}
/*
* aes_sub() - use the aese instruction to perform the AES sbox substitution
* on each byte in 'input'
*/
static u32 aes_sub(u32 input)
{
u32 ret;
__asm__("dup v1.4s, %w[in] ;"
"movi v0.16b, #0 ;"
"aese v0.16b, v1.16b ;"
"umov %w[out], v0.4s[0] ;"
: [out] "=r"(ret)
: [in] "r"(input)
: "v0","v1");
return ret;
}
int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
unsigned int key_len)
{
/*
* The AES key schedule round constants
*/
static u8 const rcon[] = {
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
};
u32 kwords = key_len / sizeof(u32);
struct aes_block *key_enc, *key_dec;
int i, j;
if (key_len != AES_KEYSIZE_128 &&
key_len != AES_KEYSIZE_192 &&
key_len != AES_KEYSIZE_256)
return -EINVAL;
memcpy(ctx->key_enc, in_key, key_len);
ctx->key_length = key_len;
kernel_neon_begin_partial(2);
for (i = 0; i < sizeof(rcon); i++) {
u32 *rki = ctx->key_enc + (i * kwords);
u32 *rko = rki + kwords;
rko[0] = ror32(aes_sub(rki[kwords - 1]), 8) ^ rcon[i] ^ rki[0];
rko[1] = rko[0] ^ rki[1];
rko[2] = rko[1] ^ rki[2];
rko[3] = rko[2] ^ rki[3];
if (key_len == AES_KEYSIZE_192) {
if (i >= 7)
break;
rko[4] = rko[3] ^ rki[4];
rko[5] = rko[4] ^ rki[5];
} else if (key_len == AES_KEYSIZE_256) {
if (i >= 6)
break;
rko[4] = aes_sub(rko[3]) ^ rki[4];
rko[5] = rko[4] ^ rki[5];
rko[6] = rko[5] ^ rki[6];
rko[7] = rko[6] ^ rki[7];
}
}
/*
* Generate the decryption keys for the Equivalent Inverse Cipher.
* This involves reversing the order of the round keys, and applying
* the Inverse Mix Columns transformation on all but the first and
* the last one.
*/
key_enc = (struct aes_block *)ctx->key_enc;
key_dec = (struct aes_block *)ctx->key_dec;
j = num_rounds(ctx);
key_dec[0] = key_enc[j];
for (i = 1, j--; j > 0; i++, j--)
__asm__("ld1 {v0.16b}, %[in] ;"
"aesimc v1.16b, v0.16b ;"
"st1 {v1.16b}, %[out] ;"
: [out] "=Q"(key_dec[i])
: [in] "Q"(key_enc[j])
: "v0","v1");
key_dec[i] = key_enc[0];
kernel_neon_end();
return 0;
}
EXPORT_SYMBOL(ce_aes_expandkey);
int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len)
{
struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
int ret;
ret = ce_aes_expandkey(ctx, in_key, key_len);
if (!ret)
return 0;
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
EXPORT_SYMBOL(ce_aes_setkey);
static struct crypto_alg aes_alg = {
.cra_name = "aes",
.cra_driver_name = "aes-ce",
.cra_priority = 250,
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = AES_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct crypto_aes_ctx),
.cra_module = THIS_MODULE,
.cra_cipher = {
.cia_min_keysize = AES_MIN_KEY_SIZE,
.cia_max_keysize = AES_MAX_KEY_SIZE,
.cia_setkey = ce_aes_setkey,
.cia_encrypt = aes_cipher_encrypt,
.cia_decrypt = aes_cipher_decrypt
}
};
static int __init aes_mod_init(void)
{
return crypto_register_alg(&aes_alg);
}
static void __exit aes_mod_exit(void)
{
crypto_unregister_alg(&aes_alg);
}
module_cpu_feature_match(AES, aes_mod_init);
module_exit(aes_mod_exit);