ipv4: use siphash instead of Jenkins in fnhe_hashfun()

commit 6457378fe796815c973f631a1904e147d6ee33b1 upstream.

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: 389806896e25 ("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>
[OP: adjusted context for 5.4 stable]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 539492998864e6f6fcdab11438e9657996b233ca..d1feec97fa062ea34ab527a772549669a9ba7ce1 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -631,14 +631,14 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash)
        kfree_rcu(oldest, rcu);
 }
 
-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)