On Mon, Nov 05, 2012 at 04:00:10PM -0500, Jarod Wilson wrote:
> The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
> first use, either on system startup or after an RNDCLEARPOOL ioctl, we
> need to take an initial random sample, store it internally in last_data,
> then pass along the value after that to the requester, so that consistency
> checks aren't being run against stale and possibly known data.
>
> CC: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> CC: "David S. Miller" <davem@xxxxxxxxxxxxx>
> CC: Neil Horman <nhorman@xxxxxxxxxxxxx>
> CC: Matt Mackall <mpm@xxxxxxxxxxx>
> CC: linux-crypto@xxxxxxxxxxxxxxx
> Signed-off-by: Jarod Wilson <jarod@xxxxxxxxxx>
> ---
> drivers/char/random.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index b86eae9..24d17b8 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -437,6 +437,7 @@ struct entropy_store {
> int entropy_count;
> int entropy_total;
> unsigned int initialized:1;
> + bool last_data_init;
> __u8 last_data[EXTRACT_SIZE];
> };
>
> @@ -967,6 +968,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
> if (fips_enabled) {
> unsigned long flags;
>
> + /* prime last_data value if need be, per fips 140-2 */
> + if (!r->last_data_init) {
> + spin_lock_irqsave(&r->lock, flags);
> + memcpy(r->last_data, tmp, EXTRACT_SIZE);
> + r->last_data_init = true;
> + spin_unlock_irqrestore(&r->lock, flags);
> + continue;
Continue? Is that left over from earlier work? Or did you have some other
purpose in mind for it?
Also, not that its in a hot path or anything, but it might be nice to
consolodate this code such that you only lock and unlock r->flags once instead
of twice here.
Best
Neil
> + }
> +
> spin_lock_irqsave(&r->lock, flags);
> if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
> panic("Hardware RNG duplicated output!\n");
> @@ -1086,6 +1096,7 @@ static void init_std_data(struct entropy_store *r)
>
> r->entropy_count = 0;
> r->entropy_total = 0;
> + r->last_data_init = false;
> mix_pool_bytes(r, &now, sizeof(now), NULL);
> for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
> if (!arch_get_random_long(&rv))
> --
> 1.7.1
>
>
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