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authorLinus Walleij <linus.walleij@linaro.org>2013-09-09 09:35:54 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2013-09-13 21:43:53 +1000
commitf5b38c5f19b1dafb413c6581cd4a0d84d3b6512f (patch)
tree6ed73974a4a8cec70834be01514c8af2852dfaf4 /drivers/crypto
parenta44bc80e66b4014e462cb8be9d354a7bc4723b7e (diff)
downloadlinux-linaro-stable-f5b38c5f19b1dafb413c6581cd4a0d84d3b6512f.tar.gz
crypto: tegra - use kernel entropy instead of ad-hoc
The way I read the Tegra AES RNG is that it has a homebrew algorithm for initializing the 128bit RNG using timespec and the unique chip ID. This looks like reinventing the (square) wheel, instead just grab 128bits from the kernel entropy pool where the time and (after another patch) chip unique ID is already mixed in. Incidentally this also gets rid of a rather ugly cross-dependence on the machine using an extern declaration. Cc: Varun Wadekar <vwadekar@nvidia.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: linux-tegra@vger.kernel.org Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto')
-rw-r--r--drivers/crypto/tegra-aes.c15
1 files changed, 3 insertions, 12 deletions
diff --git a/drivers/crypto/tegra-aes.c b/drivers/crypto/tegra-aes.c
index 2d58da972ae2..7f42bfe9fc81 100644
--- a/drivers/crypto/tegra-aes.c
+++ b/drivers/crypto/tegra-aes.c
@@ -199,8 +199,6 @@ static void aes_workqueue_handler(struct work_struct *work);
static DECLARE_WORK(aes_work, aes_workqueue_handler);
static struct workqueue_struct *aes_wq;
-extern unsigned long long tegra_chip_uid(void);
-
static inline u32 aes_readl(struct tegra_aes_dev *dd, u32 offset)
{
return readl(dd->io_base + offset);
@@ -713,9 +711,8 @@ static int tegra_aes_rng_reset(struct crypto_rng *tfm, u8 *seed,
struct tegra_aes_dev *dd = aes_dev;
struct tegra_aes_ctx *ctx = &rng_ctx;
struct tegra_aes_slot *key_slot;
- struct timespec ts;
int ret = 0;
- u64 nsec, tmp[2];
+ u8 tmp[16]; /* 16 bytes = 128 bits of entropy */
u8 *dt;
if (!ctx || !dd) {
@@ -778,14 +775,8 @@ static int tegra_aes_rng_reset(struct crypto_rng *tfm, u8 *seed,
if (dd->ivlen >= (2 * DEFAULT_RNG_BLK_SZ + AES_KEYSIZE_128)) {
dt = dd->iv + DEFAULT_RNG_BLK_SZ + AES_KEYSIZE_128;
} else {
- getnstimeofday(&ts);
- nsec = timespec_to_ns(&ts);
- do_div(nsec, 1000);
- nsec ^= dd->ctr << 56;
- dd->ctr++;
- tmp[0] = nsec;
- tmp[1] = tegra_chip_uid();
- dt = (u8 *)tmp;
+ get_random_bytes(tmp, sizeof(tmp));
+ dt = tmp;
}
memcpy(dd->dt, dt, DEFAULT_RNG_BLK_SZ);