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vsprintf: initialize siphash key using notifier

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

Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2022-11-16 17:16:38 +01:00
parent bbc7e1bed1
commit 898f1e5c37
1 changed files with 5 additions and 9 deletions
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14
lib/vsprintf.c
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@ -41,6 +41,7 @@
#include <linux/siphash.h> #include <linux/siphash.h>
#include <linux/compiler.h> #include <linux/compiler.h>
#include <linux/property.h> #include <linux/property.h>
#include <linux/notifier.h>
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
#include <linux/blkdev.h> #include <linux/blkdev.h>
#endif #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 bool filled_random_ptr_key __read_mostly;
static siphash_key_t 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)); get_random_bytes(&ptr_key, sizeof(ptr_key));
/* Pairs with smp_rmb() before reading ptr_key. */ /* Pairs with smp_rmb() before reading ptr_key. */
smp_wmb(); smp_wmb();
WRITE_ONCE(filled_random_ptr_key, true); WRITE_ONCE(filled_random_ptr_key, true);
return NOTIFY_DONE;
} }
static int __init vsprintf_init_hashval(void) 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; return 0;
} }
subsys_initcall(vsprintf_init_hashval) subsys_initcall(vsprintf_init_hashval)