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linux/drivers/crypto/padlock-aes.c
Herbert Xu 476df259cd [CRYPTO] Update IV correctly for Padlock CBC encryption 
When the Padlock does CBC encryption, the memory pointed to by EAX is
not updated at all.  Instead, it updates the value of EAX by pointing
it to the last block in the output.  Therefore to maintain the correct
semantics we need to copy the IV.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-06 13:54:09 -07:00

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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 <linux/kernel.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];
uint32_t d_data[AES_EXTENDED_KEY_SIZE];
struct {
struct cword encrypt;
struct cword decrypt;
} cword;
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 inline struct aes_ctx *aes_ctx(void *ctx)
{
return (struct aes_ctx *)ALIGN((unsigned long)ctx, PADLOCK_ALIGNMENT);
}
static int
aes_set_key(void *ctx_arg, const uint8_t *in_key, unsigned int key_len, uint32_t *flags)
{
struct aes_ctx *ctx = aes_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;
/*
* If the hardware is capable of generating the extended key
* itself we must supply the plain key for both encryption
* and decryption.
*/
ctx->E = ctx->e_data;
ctx->D = ctx->e_data;
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);
/* Prepare control words. */
memset(&ctx->cword, 0, sizeof(ctx->cword));
ctx->cword.decrypt.encdec = 1;
ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
ctx->cword.encrypt.ksize = (key_len - 16) / 8;
ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
/* Don't generate extended keys if the hardware can do it. */
if (aes_hw_extkey_available(key_len))
return 0;
ctx->D = ctx->d_data;
ctx->cword.encrypt.keygen = 1;
ctx->cword.decrypt.keygen = 1;
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 ====== */
/* These are the real call to PadLock. */
static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
void *control_word, u32 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 inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
u8 *iv, void *control_word, u32 count)
{
/* Enforce key reload. */
asm volatile ("pushfl; popfl");
/* rep xcryptcbc */
asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"
: "+S" (input), "+D" (output), "+a" (iv)
: "d" (control_word), "b" (key), "c" (count));
return iv;
}
static void
aes_encrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
{
struct aes_ctx *ctx = aes_ctx(ctx_arg);
padlock_xcrypt_ecb(in, out, ctx->E, &ctx->cword.encrypt, 1);
}
static void
aes_decrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
{
struct aes_ctx *ctx = aes_ctx(ctx_arg);
padlock_xcrypt_ecb(in, out, ctx->D, &ctx->cword.decrypt, 1);
}
static unsigned int aes_encrypt_ecb(const struct cipher_desc *desc, u8 *out,
const u8 *in, unsigned int nbytes)
{
struct aes_ctx *ctx = aes_ctx(crypto_tfm_ctx(desc->tfm));
padlock_xcrypt_ecb(in, out, ctx->E, &ctx->cword.encrypt,
nbytes / AES_BLOCK_SIZE);
return nbytes & ~(AES_BLOCK_SIZE - 1);
}
static unsigned int aes_decrypt_ecb(const struct cipher_desc *desc, u8 *out,
const u8 *in, unsigned int nbytes)
{
struct aes_ctx *ctx = aes_ctx(crypto_tfm_ctx(desc->tfm));
padlock_xcrypt_ecb(in, out, ctx->D, &ctx->cword.decrypt,
nbytes / AES_BLOCK_SIZE);
return nbytes & ~(AES_BLOCK_SIZE - 1);
}
static unsigned int aes_encrypt_cbc(const struct cipher_desc *desc, u8 *out,
const u8 *in, unsigned int nbytes)
{
struct aes_ctx *ctx = aes_ctx(crypto_tfm_ctx(desc->tfm));
u8 *iv;
iv = padlock_xcrypt_cbc(in, out, ctx->E, desc->info,
&ctx->cword.encrypt, nbytes / AES_BLOCK_SIZE);
memcpy(desc->info, iv, AES_BLOCK_SIZE);
return nbytes & ~(AES_BLOCK_SIZE - 1);
}
static unsigned int aes_decrypt_cbc(const struct cipher_desc *desc, u8 *out,
const u8 *in, unsigned int nbytes)
{
struct aes_ctx *ctx = aes_ctx(crypto_tfm_ctx(desc->tfm));
padlock_xcrypt_cbc(in, out, ctx->D, desc->info, &ctx->cword.decrypt,
nbytes / AES_BLOCK_SIZE);
return nbytes & ~(AES_BLOCK_SIZE - 1);
}
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_alignmask = PADLOCK_ALIGNMENT - 1,
.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,
.cia_encrypt_ecb = aes_encrypt_ecb,
.cia_decrypt_ecb = aes_decrypt_ecb,
.cia_encrypt_cbc = aes_encrypt_cbc,
.cia_decrypt_cbc = aes_decrypt_cbc,
}
}
};
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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