ipv4: use siphash instead of Jenkins in fnhe_hashfun()

A group of security researchers brought to our attention
the weakness of hash function used in fnhe_hashfun().

Lets use siphash instead of Jenkins Hash, to considerably
reduce security risks.

Also remove the inline keyword, this really is distracting.

Fixes: d546c621542d ("ipv4: harden fnhe_hashfun()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Keyu Man <kman001@ucr.edu>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 99c0694..a6f20ee 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -600,14 +600,14 @@ static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
        return oldest;
 }
 
-static inline u32 fnhe_hashfun(__be32 daddr)
+static u32 fnhe_hashfun(__be32 daddr)
 {
-       static u32 fnhe_hashrnd __read_mostly;
-       u32 hval;
+       static siphash_key_t fnhe_hash_key __read_mostly;
+       u64 hval;
 
-       net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
-       hval = jhash_1word((__force u32)daddr, fnhe_hashrnd);
-       return hash_32(hval, FNHE_HASH_SHIFT);
+       net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));
+       hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);
+       return hash_64(hval, FNHE_HASH_SHIFT);
 }
 
 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)