Willy Tarreau <w...@1wt.eu> wrote:
> diff --git a/include/linux/random.h b/include/linux/random.h
> index 9ab7443bd91b..9e22973b207c 100644
> --- a/include/linux/random.h
> +++ b/include/linux/random.h
> @@ -12,6 +12,7 @@
> #include <linux/list.h>
> #include <linux/once.h>
> #include <asm/percpu.h>
> +#include <linux/siphash.h>
>
> #include <uapi/linux/random.h>
>
> @@ -117,7 +118,8 @@ void prandom_seed(u32 seed);
> void prandom_reseed_late(void);
>
> struct rnd_state {
> - __u32 s1, s2, s3, s4;
> + siphash_key_t key;
> + uint64_t counter;
> };
Does the siphash_key really need to be percpu?
The counter is different of course.
Alternative would be to siphash a few prandom_u32 results
if the extra u64 is too much storage.
> DECLARE_PER_CPU(struct rnd_state, net_rand_state);
> @@ -161,12 +163,14 @@ static inline u32 __seed(u32 x, u32 m)
> */
> static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
> {
> +#if 0
> u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
>
> state->s1 = __seed(i, 2U);
> state->s2 = __seed(i, 8U);
> state->s3 = __seed(i, 16U);
> state->s4 = __seed(i, 128U);
> +#endif
> }
[..]
Can't we keep prandom_u32 as-is...? Most of the usage, esp. in the
packet schedulers, is fine.
I'd much rather have a prandom_u32_hashed() or whatever for
those cases where some bits might leak to the outside and then convert
those prandom_u32 users over to the siphashed version.
