aes_ctr.c
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/**
* AES CTR routines supporting VMX instructions on the Power 8
*
* Copyright (C) 2015 International Business Machines Inc.
*
* 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; version 2 only.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
*/
#include <linux/types.h>
#include <linux/err.h>
#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <asm/switch_to.h>
#include <crypto/aes.h>
#include <crypto/scatterwalk.h>
#include "aesp8-ppc.h"
struct p8_aes_ctr_ctx {
struct crypto_blkcipher *fallback;
struct aes_key enc_key;
};
static int p8_aes_ctr_init(struct crypto_tfm *tfm)
{
const char *alg;
struct crypto_blkcipher *fallback;
struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
if (!(alg = crypto_tfm_alg_name(tfm))) {
printk(KERN_ERR "Failed to get algorithm name.\n");
return -ENOENT;
}
fallback =
crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
if (IS_ERR(fallback)) {
printk(KERN_ERR
"Failed to allocate transformation for '%s': %ld\n",
alg, PTR_ERR(fallback));
return PTR_ERR(fallback);
}
printk(KERN_INFO "Using '%s' as fallback implementation.\n",
crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
crypto_blkcipher_set_flags(
fallback,
crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
ctx->fallback = fallback;
return 0;
}
static void p8_aes_ctr_exit(struct crypto_tfm *tfm)
{
struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
if (ctx->fallback) {
crypto_free_blkcipher(ctx->fallback);
ctx->fallback = NULL;
}
}
static int p8_aes_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
int ret;
struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
pagefault_disable();
enable_kernel_altivec();
enable_kernel_vsx();
ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
pagefault_enable();
ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
return ret;
}
static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
struct blkcipher_walk *walk)
{
u8 *ctrblk = walk->iv;
u8 keystream[AES_BLOCK_SIZE];
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
unsigned int nbytes = walk->nbytes;
pagefault_disable();
enable_kernel_altivec();
enable_kernel_vsx();
aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
pagefault_enable();
crypto_xor(keystream, src, nbytes);
memcpy(dst, keystream, nbytes);
crypto_inc(ctrblk, AES_BLOCK_SIZE);
}
static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
int ret;
u64 inc;
struct blkcipher_walk walk;
struct p8_aes_ctr_ctx *ctx =
crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
struct blkcipher_desc fallback_desc = {
.tfm = ctx->fallback,
.info = desc->info,
.flags = desc->flags
};
if (in_interrupt()) {
ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
nbytes);
} else {
blkcipher_walk_init(&walk, dst, src, nbytes);
ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
pagefault_disable();
enable_kernel_altivec();
enable_kernel_vsx();
aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
walk.dst.virt.addr,
(nbytes &
AES_BLOCK_MASK) /
AES_BLOCK_SIZE,
&ctx->enc_key,
walk.iv);
pagefault_enable();
/* We need to update IV mostly for last bytes/round */
inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
if (inc > 0)
while (inc--)
crypto_inc(walk.iv, AES_BLOCK_SIZE);
nbytes &= AES_BLOCK_SIZE - 1;
ret = blkcipher_walk_done(desc, &walk, nbytes);
}
if (walk.nbytes) {
p8_aes_ctr_final(ctx, &walk);
ret = blkcipher_walk_done(desc, &walk, 0);
}
}
return ret;
}
struct crypto_alg p8_aes_ctr_alg = {
.cra_name = "ctr(aes)",
.cra_driver_name = "p8_aes_ctr",
.cra_module = THIS_MODULE,
.cra_priority = 2000,
.cra_type = &crypto_blkcipher_type,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
.cra_alignmask = 0,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
.cra_init = p8_aes_ctr_init,
.cra_exit = p8_aes_ctr_exit,
.cra_blkcipher = {
.ivsize = AES_BLOCK_SIZE,
.min_keysize = AES_MIN_KEY_SIZE,
.max_keysize = AES_MAX_KEY_SIZE,
.setkey = p8_aes_ctr_setkey,
.encrypt = p8_aes_ctr_crypt,
.decrypt = p8_aes_ctr_crypt,
},
};