From fc6856b5b9dc056e7a54436f1f7eb0b9a6f68895 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 16 Mar 2017 15:28:16 +0100 Subject: hashtables: get_random_int is now more secure, so expose directly On 4.11, get_random_u32 now either uses chacha or rdrand, rather than the horrible former MD5 construction, so we feel more comfortable exposing RNG output directly. On older kernels, we fall back to something a bit disgusting. --- src/compat/compat.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'src/compat/compat.h') diff --git a/src/compat/compat.h b/src/compat/compat.h index 141cad7..4e6010f 100644 --- a/src/compat/compat.h +++ b/src/compat/compat.h @@ -171,6 +171,25 @@ static inline void skb_reset_tc(struct sk_buff *skb) } #endif +#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 11, 0) +#include +static inline u32 get_random_u32(void) +{ + static siphash_key_t key; + static u32 counter = 0; +#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0) + static bool has_seeded = false; + if (unlikely(!has_seeded)) { + get_random_bytes(&key, sizeof(key)); + has_seeded = true; + } +#else + get_random_once(&key, sizeof(key)); +#endif + return siphash_2u32(counter++, get_random_int(), &key); +} +#endif + /* https://lkml.org/lkml/2015/6/12/415 */ #include static inline struct net_device *netdev_pub(void *dev) -- cgit v1.2.3-59-g8ed1b