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hwrng: fetch randomness only after device init

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Commit d9e7972 "hwrng: add randomness to system from rng sources"
added a call to rng_get_data() from the hwrng_register() function.
However, some rng devices need initialization before data can be read
from them.

This commit makes the call to rng_get_data() depend on no init fn
pointer being registered by the device.  If an init function is
registered, this call is made after device init.

CC: Kees Cook <keescook@chromium.org>
CC: Jason Cooper <jason@lakedaemon.net>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: <stable@vger.kernel.org> # For v3.15+
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
nyyu 2022-08-21 20:27:44 +02:00 committed by followmsi
parent 7740dd2d25
commit b27211a486
1 changed files with 30 additions and 10 deletions
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40
drivers/char/hw_random/core.c
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@ -64,20 +64,34 @@ MODULE_PARM_DESC(current_quality,
static void start_khwrngd(void);
static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
int wait);
static size_t rng_buffer_size(void)
{
return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
}
static void add_early_randomness(struct hwrng *rng)
{
unsigned char bytes[16];
int bytes_read;
bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
if (bytes_read > 0)
add_device_randomness(bytes, bytes_read);
}
static inline int hwrng_init(struct hwrng *rng)
{
int err;
if (rng->init) {
err = rng->init(rng);
if (err)
return err;
int ret;
ret = rng->init(rng);
if (ret)
return ret;
}
add_early_randomness(rng);
if (current_quality > 0 && !hwrng_fill)
start_khwrngd();
@ -352,8 +366,6 @@ int hwrng_register(struct hwrng *rng)
{
int err = -EINVAL;
struct hwrng *old_rng, *tmp;
unsigned char bytes[16];
int bytes_read;
if (rng->name == NULL ||
(rng->data_read == NULL && rng->read == NULL))
@ -402,9 +414,17 @@ int hwrng_register(struct hwrng *rng)
INIT_LIST_HEAD(&rng->list);
list_add_tail(&rng->list, &rng_list);
bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
if (bytes_read > 0)
add_device_randomness(bytes, bytes_read);
if (old_rng && !rng->init) {
/*
* Use a new device's input to add some randomness to
* the system. If this rng device isn't going to be
* used right away, its init function hasn't been
* called yet; so only use the randomness from devices
* that don't need an init callback.
*/
add_early_randomness(rng);
}
out_unlock:
mutex_unlock(&rng_mutex);
out: