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linux/drivers/crypto/padlock-aes.c

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/*
* Cryptographic API.
*
* Support for VIA PadLock hardware crypto engine.
*
* Copyright (c) 2004 Michal Ludvig <michal@logix.cz>
*
* Key expansion routine taken from crypto/aes.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* ---------------------------------------------------------------------------
* Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
* All rights reserved.
*
* LICENSE TERMS
*
* The free distribution and use of this software in both source and binary
* form is allowed (with or without changes) provided that:
*
* 1. distributions of this source code include the above copyright
* notice, this list of conditions and the following disclaimer;
*
* 2. distributions in binary form include the above copyright
* notice, this list of conditions and the following disclaimer
* in the documentation and/or other associated materials;
*
* 3. the copyright holder's name is not used to endorse products
* built using this software without specific written permission.
*
* ALTERNATIVELY, provided that this notice is retained in full, this product
* may be distributed under the terms of the GNU General Public License (GPL),
* in which case the provisions of the GPL apply INSTEAD OF those given above.
*
* DISCLAIMER
*
* This software is provided 'as is' with no explicit or implied warranties
* in respect of its properties, including, but not limited to, correctness
* and/or fitness for purpose.
* ---------------------------------------------------------------------------
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include <linux/interrupt.h>
#include <asm/byteorder.h>
#include "padlock.h"
#define AES_MIN_KEY_SIZE 16 /* in uint8_t units */
#define AES_MAX_KEY_SIZE 32 /* ditto */
#define AES_BLOCK_SIZE 16 /* ditto */
#define AES_EXTENDED_KEY_SIZE 64 /* in uint32_t units */
#define AES_EXTENDED_KEY_SIZE_B (AES_EXTENDED_KEY_SIZE * sizeof(uint32_t))
struct aes_ctx {
uint32_t e_data[AES_EXTENDED_KEY_SIZE+4];
uint32_t d_data[AES_EXTENDED_KEY_SIZE+4];
uint32_t *E;
uint32_t *D;
int key_length;
};
/* ====== Key management routines ====== */
static inline uint32_t
generic_rotr32 (const uint32_t x, const unsigned bits)
{
const unsigned n = bits % 32;
return (x >> n) | (x << (32 - n));
}
static inline uint32_t
generic_rotl32 (const uint32_t x, const unsigned bits)
{
const unsigned n = bits % 32;
return (x << n) | (x >> (32 - n));
}
#define rotl generic_rotl32
#define rotr generic_rotr32
/*
* #define byte(x, nr) ((unsigned char)((x) >> (nr*8)))
*/
static inline uint8_t
byte(const uint32_t x, const unsigned n)
{
return x >> (n << 3);
}
#define uint32_t_in(x) le32_to_cpu(*(const uint32_t *)(x))
#define uint32_t_out(to, from) (*(uint32_t *)(to) = cpu_to_le32(from))
#define E_KEY ctx->E
#define D_KEY ctx->D
static uint8_t pow_tab[256];
static uint8_t log_tab[256];
static uint8_t sbx_tab[256];
static uint8_t isb_tab[256];
static uint32_t rco_tab[10];
static uint32_t ft_tab[4][256];
static uint32_t it_tab[4][256];
static uint32_t fl_tab[4][256];
static uint32_t il_tab[4][256];
static inline uint8_t
f_mult (uint8_t a, uint8_t b)
{
uint8_t aa = log_tab[a], cc = aa + log_tab[b];
return pow_tab[cc + (cc < aa ? 1 : 0)];
}
#define ff_mult(a,b) (a && b ? f_mult(a, b) : 0)
#define f_rn(bo, bi, n, k) \
bo[n] = ft_tab[0][byte(bi[n],0)] ^ \
ft_tab[1][byte(bi[(n + 1) & 3],1)] ^ \
ft_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
#define i_rn(bo, bi, n, k) \
bo[n] = it_tab[0][byte(bi[n],0)] ^ \
it_tab[1][byte(bi[(n + 3) & 3],1)] ^ \
it_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
#define ls_box(x) \
( fl_tab[0][byte(x, 0)] ^ \
fl_tab[1][byte(x, 1)] ^ \
fl_tab[2][byte(x, 2)] ^ \
fl_tab[3][byte(x, 3)] )
#define f_rl(bo, bi, n, k) \
bo[n] = fl_tab[0][byte(bi[n],0)] ^ \
fl_tab[1][byte(bi[(n + 1) & 3],1)] ^ \
fl_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
#define i_rl(bo, bi, n, k) \
bo[n] = il_tab[0][byte(bi[n],0)] ^ \
il_tab[1][byte(bi[(n + 3) & 3],1)] ^ \
il_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
static void
gen_tabs (void)
{
uint32_t i, t;
uint8_t p, q;
/* log and power tables for GF(2**8) finite field with
0x011b as modular polynomial - the simplest prmitive
root is 0x03, used here to generate the tables */
for (i = 0, p = 1; i < 256; ++i) {
pow_tab[i] = (uint8_t) p;
log_tab[p] = (uint8_t) i;
p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
}
log_tab[1] = 0;
for (i = 0, p = 1; i < 10; ++i) {
rco_tab[i] = p;
p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
}
for (i = 0; i < 256; ++i) {
p = (i ? pow_tab[255 - log_tab[i]] : 0);
q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
sbx_tab[i] = p;
isb_tab[p] = (uint8_t) i;
}
for (i = 0; i < 256; ++i) {
p = sbx_tab[i];
t = p;
fl_tab[0][i] = t;
fl_tab[1][i] = rotl (t, 8);
fl_tab[2][i] = rotl (t, 16);
fl_tab[3][i] = rotl (t, 24);
t = ((uint32_t) ff_mult (2, p)) |
((uint32_t) p << 8) |
((uint32_t) p << 16) | ((uint32_t) ff_mult (3, p) << 24);
ft_tab[0][i] = t;
ft_tab[1][i] = rotl (t, 8);
ft_tab[2][i] = rotl (t, 16);
ft_tab[3][i] = rotl (t, 24);
p = isb_tab[i];
t = p;
il_tab[0][i] = t;
il_tab[1][i] = rotl (t, 8);
il_tab[2][i] = rotl (t, 16);
il_tab[3][i] = rotl (t, 24);
t = ((uint32_t) ff_mult (14, p)) |
((uint32_t) ff_mult (9, p) << 8) |
((uint32_t) ff_mult (13, p) << 16) |
((uint32_t) ff_mult (11, p) << 24);
it_tab[0][i] = t;
it_tab[1][i] = rotl (t, 8);
it_tab[2][i] = rotl (t, 16);
it_tab[3][i] = rotl (t, 24);
}
}
#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
#define imix_col(y,x) \
u = star_x(x); \
v = star_x(u); \
w = star_x(v); \
t = w ^ (x); \
(y) = u ^ v ^ w; \
(y) ^= rotr(u ^ t, 8) ^ \
rotr(v ^ t, 16) ^ \
rotr(t,24)
/* initialise the key schedule from the user supplied key */
#define loop4(i) \
{ t = rotr(t, 8); t = ls_box(t) ^ rco_tab[i]; \
t ^= E_KEY[4 * i]; E_KEY[4 * i + 4] = t; \
t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t; \
t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t; \
t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t; \
}
#define loop6(i) \
{ t = rotr(t, 8); t = ls_box(t) ^ rco_tab[i]; \
t ^= E_KEY[6 * i]; E_KEY[6 * i + 6] = t; \
t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t; \
t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t; \
t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t; \
t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t; \
t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t; \
}
#define loop8(i) \
{ t = rotr(t, 8); ; t = ls_box(t) ^ rco_tab[i]; \
t ^= E_KEY[8 * i]; E_KEY[8 * i + 8] = t; \
t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t; \
t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t; \
t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t; \
t = E_KEY[8 * i + 4] ^ ls_box(t); \
E_KEY[8 * i + 12] = t; \
t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t; \
t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t; \
t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t; \
}
/* Tells whether the ACE is capable to generate
the extended key for a given key_len. */
static inline int
aes_hw_extkey_available(uint8_t key_len)
{
/* TODO: We should check the actual CPU model/stepping
as it's possible that the capability will be
added in the next CPU revisions. */
if (key_len == 16)
return 1;
return 0;
}
static int
aes_set_key(void *ctx_arg, const uint8_t *in_key, unsigned int key_len, uint32_t *flags)
{
struct aes_ctx *ctx = ctx_arg;
uint32_t i, t, u, v, w;
uint32_t P[AES_EXTENDED_KEY_SIZE];
uint32_t rounds;
if (key_len != 16 && key_len != 24 && key_len != 32) {
*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
ctx->key_length = key_len;
ctx->E = ctx->e_data;
ctx->D = ctx->d_data;
/* Ensure 16-Bytes alignmentation of keys for VIA PadLock. */
if ((int)(ctx->e_data) & 0x0F)
ctx->E += 4 - (((int)(ctx->e_data) & 0x0F) / sizeof (ctx->e_data[0]));
if ((int)(ctx->d_data) & 0x0F)
ctx->D += 4 - (((int)(ctx->d_data) & 0x0F) / sizeof (ctx->d_data[0]));
E_KEY[0] = uint32_t_in (in_key);
E_KEY[1] = uint32_t_in (in_key + 4);
E_KEY[2] = uint32_t_in (in_key + 8);
E_KEY[3] = uint32_t_in (in_key + 12);
/* Don't generate extended keys if the hardware can do it. */
if (aes_hw_extkey_available(key_len))
return 0;
switch (key_len) {
case 16:
t = E_KEY[3];
for (i = 0; i < 10; ++i)
loop4 (i);
break;
case 24:
E_KEY[4] = uint32_t_in (in_key + 16);
t = E_KEY[5] = uint32_t_in (in_key + 20);
for (i = 0; i < 8; ++i)
loop6 (i);
break;
case 32:
E_KEY[4] = uint32_t_in (in_key + 16);
E_KEY[5] = uint32_t_in (in_key + 20);
E_KEY[6] = uint32_t_in (in_key + 24);
t = E_KEY[7] = uint32_t_in (in_key + 28);
for (i = 0; i < 7; ++i)
loop8 (i);
break;
}
D_KEY[0] = E_KEY[0];
D_KEY[1] = E_KEY[1];
D_KEY[2] = E_KEY[2];
D_KEY[3] = E_KEY[3];
for (i = 4; i < key_len + 24; ++i) {
imix_col (D_KEY[i], E_KEY[i]);
}
/* PadLock needs a different format of the decryption key. */
rounds = 10 + (key_len - 16) / 4;
for (i = 0; i < rounds; i++) {
P[((i + 1) * 4) + 0] = D_KEY[((rounds - i - 1) * 4) + 0];
P[((i + 1) * 4) + 1] = D_KEY[((rounds - i - 1) * 4) + 1];
P[((i + 1) * 4) + 2] = D_KEY[((rounds - i - 1) * 4) + 2];
P[((i + 1) * 4) + 3] = D_KEY[((rounds - i - 1) * 4) + 3];
}
P[0] = E_KEY[(rounds * 4) + 0];
P[1] = E_KEY[(rounds * 4) + 1];
P[2] = E_KEY[(rounds * 4) + 2];
P[3] = E_KEY[(rounds * 4) + 3];
memcpy(D_KEY, P, AES_EXTENDED_KEY_SIZE_B);
return 0;
}
/* ====== Encryption/decryption routines ====== */
/* This is the real call to PadLock. */
static inline void
padlock_xcrypt_ecb(uint8_t *input, uint8_t *output, uint8_t *key,
void *control_word, uint32_t count)
{
asm volatile ("pushfl; popfl"); /* enforce key reload. */
asm volatile (".byte 0xf3,0x0f,0xa7,0xc8" /* rep xcryptecb */
: "+S"(input), "+D"(output)
: "d"(control_word), "b"(key), "c"(count));
}
static void
aes_padlock(void *ctx_arg, uint8_t *out_arg, const uint8_t *in_arg, int encdec)
{
/* Don't blindly modify this structure - the items must
fit on 16-Bytes boundaries! */
struct padlock_xcrypt_data {
uint8_t buf[AES_BLOCK_SIZE];
union cword cword;
};
struct aes_ctx *ctx = ctx_arg;
char bigbuf[sizeof(struct padlock_xcrypt_data) + 16];
struct padlock_xcrypt_data *data;
void *key;
/* Place 'data' at the first 16-Bytes aligned address in 'bigbuf'. */
if (((long)bigbuf) & 0x0F)
data = (void*)(bigbuf + 16 - ((long)bigbuf & 0x0F));
else
data = (void*)bigbuf;
/* Prepare Control word. */
memset (data, 0, sizeof(struct padlock_xcrypt_data));
data->cword.b.encdec = !encdec; /* in the rest of cryptoapi ENC=1/DEC=0 */
data->cword.b.rounds = 10 + (ctx->key_length - 16) / 4;
data->cword.b.ksize = (ctx->key_length - 16) / 8;
/* Is the hardware capable to generate the extended key? */
if (!aes_hw_extkey_available(ctx->key_length))
data->cword.b.keygen = 1;
/* ctx->E starts with a plain key - if the hardware is capable
to generate the extended key itself we must supply
the plain key for both Encryption and Decryption. */
if (encdec == CRYPTO_DIR_ENCRYPT || data->cword.b.keygen == 0)
key = ctx->E;
else
key = ctx->D;
memcpy(data->buf, in_arg, AES_BLOCK_SIZE);
padlock_xcrypt_ecb(data->buf, data->buf, key, &data->cword, 1);
memcpy(out_arg, data->buf, AES_BLOCK_SIZE);
}
static void
aes_encrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
{
aes_padlock(ctx_arg, out, in, CRYPTO_DIR_ENCRYPT);
}
static void
aes_decrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
{
aes_padlock(ctx_arg, out, in, CRYPTO_DIR_DECRYPT);
}
static struct crypto_alg aes_alg = {
.cra_name = "aes",
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = AES_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct aes_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(aes_alg.cra_list),
.cra_u = {
.cipher = {
.cia_min_keysize = AES_MIN_KEY_SIZE,
.cia_max_keysize = AES_MAX_KEY_SIZE,
.cia_setkey = aes_set_key,
.cia_encrypt = aes_encrypt,
.cia_decrypt = aes_decrypt
}
}
};
int __init padlock_init_aes(void)
{
printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
gen_tabs();
return crypto_register_alg(&aes_alg);
}
void __exit padlock_fini_aes(void)
{
crypto_unregister_alg(&aes_alg);
}
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