Commit 898f1e5c authored by Jason A. Donenfeld's avatar Jason A. Donenfeld
Browse files

vsprintf: initialize siphash key using notifier 



Rather than polling every second, use the new notifier to do this at
exactly the right moment.

Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent bbc7e1be

lib/vsprintf.c

+5 −9
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/siphash.h>

#include <linux/compiler.h>

#include <linux/property.h>

#include <linux/notifier.h>

#ifdef CONFIG_BLOCK

#include <linux/blkdev.h>

#endif
@@ -752,26 +753,21 @@ early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable); 


static bool filled_random_ptr_key __read_mostly;

static siphash_key_t ptr_key __read_mostly;

static void fill_ptr_key_workfn(struct work_struct *work);

static DECLARE_DELAYED_WORK(fill_ptr_key_work, fill_ptr_key_workfn);



static void fill_ptr_key_workfn(struct work_struct *work)

static int fill_ptr_key(struct notifier_block *nb, unsigned long action, void *data)

{

	if (!rng_is_initialized()) {

		queue_delayed_work(system_unbound_wq, &fill_ptr_key_work, HZ  * 2);

		return;

	}



	get_random_bytes(&ptr_key, sizeof(ptr_key));



	/* Pairs with smp_rmb() before reading ptr_key. */

	smp_wmb();

	WRITE_ONCE(filled_random_ptr_key, true);

	return NOTIFY_DONE;

}



static int __init vsprintf_init_hashval(void)

{

	fill_ptr_key_workfn(NULL);

	static struct notifier_block fill_ptr_key_nb = { .notifier_call = fill_ptr_key };

	execute_with_initialized_rng(&fill_ptr_key_nb);

	return 0;

}

subsys_initcall(vsprintf_init_hashval)