Commit 6c0eace6 authored by Jason A. Donenfeld's avatar Jason A. Donenfeld
Browse files

random: access input_pool_data directly rather than through pointer 



This gets rid of another abstraction we no longer need. It would be nice
if we could instead make pool an array rather than a pointer, but the
latent entropy plugin won't be able to do its magic in that case. So
instead we put all accesses to the input pool's actual data through the
input_pool_data array directly.

Reviewed-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent 18263c4e

drivers/char/random.c

+8 −13
Original line number Diff line number Diff line
@@ -496,17 +496,12 @@ MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); 
static u32 input_pool_data[POOL_WORDS] __latent_entropy;



static struct {

	/* read-only data: */

	u32 *pool;



	/* read-write data: */

	spinlock_t lock;

	u16 add_ptr;

	u16 input_rotate;

	int entropy_count;

} input_pool = {

	.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),

	.pool = input_pool_data

};



static ssize_t extract_entropy(void *buf, size_t nbytes, int min);
@@ -544,15 +539,15 @@ static void _mix_pool_bytes(const void *in, int nbytes) 
		i = (i - 1) & POOL_WORDMASK;



		/* XOR in the various taps */

		w ^= input_pool.pool[i];

		w ^= input_pool.pool[(i + POOL_TAP1) & POOL_WORDMASK];

		w ^= input_pool.pool[(i + POOL_TAP2) & POOL_WORDMASK];

		w ^= input_pool.pool[(i + POOL_TAP3) & POOL_WORDMASK];

		w ^= input_pool.pool[(i + POOL_TAP4) & POOL_WORDMASK];

		w ^= input_pool.pool[(i + POOL_TAP5) & POOL_WORDMASK];

		w ^= input_pool_data[i];

		w ^= input_pool_data[(i + POOL_TAP1) & POOL_WORDMASK];

		w ^= input_pool_data[(i + POOL_TAP2) & POOL_WORDMASK];

		w ^= input_pool_data[(i + POOL_TAP3) & POOL_WORDMASK];

		w ^= input_pool_data[(i + POOL_TAP4) & POOL_WORDMASK];

		w ^= input_pool_data[(i + POOL_TAP5) & POOL_WORDMASK];



		/* Mix the result back in with a twist */

		input_pool.pool[i] = (w >> 3) ^ twist_table[w & 7];

		input_pool_data[i] = (w >> 3) ^ twist_table[w & 7];



		/*

		 * Normally, we add 7 bits of rotation to the pool.
@@ -1369,7 +1364,7 @@ static void extract_buf(u8 *out) 


	/* Generate a hash across the pool */

	spin_lock_irqsave(&input_pool.lock, flags);

	blake2s_update(&state, (const u8 *)input_pool.pool, POOL_BYTES);

	blake2s_update(&state, (const u8 *)input_pool_data, POOL_BYTES);

	blake2s_final(&state, hash); /* final zeros out state */



	/*