diff options
| author | Amit Shah <amit.shah@redhat.com> | 2014-07-10 15:42:34 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-28 08:08:27 -0700 |
| commit | f7eb924e4e591ead2e07dc9f2fabfaa5c4a6c31c (patch) | |
| tree | 6fc672c7f8fc906cf21f37d30121556b94c012e2 | |
| parent | 6ffb863bbe53b5f0622b1a3f4797d4713721f9cb (diff) | |
hwrng: fetch randomness only after device init
commit d3cc7996473a7bdd33256029988ea690754e4e2a upstream.
Commit d9e7972619334 "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>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/char/hw_random/core.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 334601cc81c..2a451b14b3c 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -55,16 +55,35 @@ static DEFINE_MUTEX(rng_mutex); static int data_avail; static u8 *rng_buffer; +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) { - if (!rng->init) - return 0; - return rng->init(rng); + if (rng->init) { + int ret; + + ret = rng->init(rng); + if (ret) + return ret; + } + add_early_randomness(rng); + return 0; } static inline void hwrng_cleanup(struct hwrng *rng) @@ -304,8 +323,6 @@ 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)) @@ -347,9 +364,17 @@ 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: |