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crypto: s390 - fix concurrency issue in aes-ctr mode

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The aes-ctr mode uses one preallocated page without any concurrency
protection. When multiple threads run aes-ctr encryption or decryption
this can lead to data corruption.

The patch introduces locking for the page and a fallback solution with
slower en/decryption performance in concurrency situations.

Cc: stable@vger.kernel.org
Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Harald Freudenberger 2014-01-16 16:01:11 +01:00 committed by Herbert Xu
parent 13c789a6b2
commit 0519e9ad89
1 changed files with 46 additions and 19 deletions
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65
arch/s390/crypto/aes_s390.c
View file

@ -25,6 +25,7 @@
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include "crypt_s390.h"
#define AES_KEYLEN_128 1
@ -32,6 +33,7 @@
#define AES_KEYLEN_256 4
static u8 *ctrblk;
static DEFINE_SPINLOCK(ctrblk_lock);
static char keylen_flag;
struct s390_aes_ctx {
@ -758,43 +760,67 @@ static int ctr_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
return aes_set_key(tfm, in_key, key_len);
}
static unsigned int __ctrblk_init(u8 *ctrptr, unsigned int nbytes)
{
unsigned int i, n;
/* only use complete blocks, max. PAGE_SIZE */
n = (nbytes > PAGE_SIZE) ? PAGE_SIZE : nbytes & ~(AES_BLOCK_SIZE - 1);
for (i = AES_BLOCK_SIZE; i < n; i += AES_BLOCK_SIZE) {
memcpy(ctrptr + i, ctrptr + i - AES_BLOCK_SIZE,
AES_BLOCK_SIZE);
crypto_inc(ctrptr + i, AES_BLOCK_SIZE);
}
return n;
}
static int ctr_aes_crypt(struct blkcipher_desc *desc, long func,
struct s390_aes_ctx *sctx, struct blkcipher_walk *walk)
{
int ret = blkcipher_walk_virt_block(desc, walk, AES_BLOCK_SIZE);
unsigned int i, n, nbytes;
u8 buf[AES_BLOCK_SIZE];
u8 *out, *in;
unsigned int n, nbytes;
u8 buf[AES_BLOCK_SIZE], ctrbuf[AES_BLOCK_SIZE];
u8 *out, *in, *ctrptr = ctrbuf;
if (!walk->nbytes)
return ret;
memcpy(ctrblk, walk->iv, AES_BLOCK_SIZE);
if (spin_trylock(&ctrblk_lock))
ctrptr = ctrblk;
memcpy(ctrptr, walk->iv, AES_BLOCK_SIZE);
while ((nbytes = walk->nbytes) >= AES_BLOCK_SIZE) {
out = walk->dst.virt.addr;
in = walk->src.virt.addr;
while (nbytes >= AES_BLOCK_SIZE) {
/* only use complete blocks, max. PAGE_SIZE */
n = (nbytes > PAGE_SIZE) ? PAGE_SIZE :
nbytes & ~(AES_BLOCK_SIZE - 1);
for (i = AES_BLOCK_SIZE; i < n; i += AES_BLOCK_SIZE) {
memcpy(ctrblk + i, ctrblk + i - AES_BLOCK_SIZE,
AES_BLOCK_SIZE);
crypto_inc(ctrblk + i, AES_BLOCK_SIZE);
}
ret = crypt_s390_kmctr(func, sctx->key, out, in, n, ctrblk);
if (ret < 0 || ret != n)
if (ctrptr == ctrblk)
n = __ctrblk_init(ctrptr, nbytes);
else
n = AES_BLOCK_SIZE;
ret = crypt_s390_kmctr(func, sctx->key, out, in,
n, ctrptr);
if (ret < 0 || ret != n) {
if (ctrptr == ctrblk)
spin_unlock(&ctrblk_lock);
return -EIO;
}
if (n > AES_BLOCK_SIZE)
memcpy(ctrblk, ctrblk + n - AES_BLOCK_SIZE,
memcpy(ctrptr, ctrptr + n - AES_BLOCK_SIZE,
AES_BLOCK_SIZE);
crypto_inc(ctrblk, AES_BLOCK_SIZE);
crypto_inc(ctrptr, AES_BLOCK_SIZE);
out += n;
in += n;
nbytes -= n;
}
ret = blkcipher_walk_done(desc, walk, nbytes);
}
if (ctrptr == ctrblk) {
if (nbytes)
memcpy(ctrbuf, ctrptr, AES_BLOCK_SIZE);
else
memcpy(walk->iv, ctrptr, AES_BLOCK_SIZE);
spin_unlock(&ctrblk_lock);
}
/*
* final block may be < AES_BLOCK_SIZE, copy only nbytes
*/
@ -802,14 +828,15 @@ static int ctr_aes_crypt(struct blkcipher_desc *desc, long func,
out = walk->dst.virt.addr;
in = walk->src.virt.addr;
ret = crypt_s390_kmctr(func, sctx->key, buf, in,
AES_BLOCK_SIZE, ctrblk);
AES_BLOCK_SIZE, ctrbuf);
if (ret < 0 || ret != AES_BLOCK_SIZE)
return -EIO;
memcpy(out, buf, nbytes);
crypto_inc(ctrblk, AES_BLOCK_SIZE);
crypto_inc(ctrbuf, AES_BLOCK_SIZE);
ret = blkcipher_walk_done(desc, walk, 0);
memcpy(walk->iv, ctrbuf, AES_BLOCK_SIZE);
}
memcpy(walk->iv, ctrblk, AES_BLOCK_SIZE);
return ret;
}