Commit ec8f02da authored by Jarod Wilson's avatar Jarod Wilson Committed by Theodore Ts'o
Browse files

random: prime last_data value per fips requirements 



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@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Matt Mackall <mpm@selenic.com>
CC: linux-crypto@vger.kernel.org
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 8eb2ffbf

drivers/char/random.c

+17 −0
Original line number Diff line number Diff line
@@ -433,6 +433,7 @@ struct entropy_store { 
	int entropy_count;

	int entropy_total;

	unsigned int initialized:1;

	bool last_data_init;

	__u8 last_data[EXTRACT_SIZE];

};
@@ -953,6 +954,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, 
	ssize_t ret = 0, i;

	__u8 tmp[EXTRACT_SIZE];



	/* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */

	if (fips_enabled && !r->last_data_init)

		nbytes += EXTRACT_SIZE;



	trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);

	xfer_secondary_pool(r, nbytes);

	nbytes = account(r, nbytes, min, reserved);
@@ -963,6 +968,17 @@ 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;

				nbytes -= EXTRACT_SIZE;

				spin_unlock_irqrestore(&r->lock, flags);

				extract_buf(r, tmp);

			}



			spin_lock_irqsave(&r->lock, flags);

			if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))

				panic("Hardware RNG duplicated output!\n");
@@ -1082,6 +1098,7 @@ 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))

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