ipv4: harden fnhe_hashfun()
Lets make this hash function a bit secure, as ICMP attacks are still
in the wild.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index f30fd55..dc9d2a2 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -65,7 +65,8 @@
struct fib_nh_exception __rcu *chain;
};
-#define FNHE_HASH_SIZE 2048
+#define FNHE_HASH_SHIFT 11
+#define FNHE_HASH_SIZE (1 << FNHE_HASH_SHIFT)
#define FNHE_RECLAIM_DEPTH 5
struct fib_nh {
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 44b0cbd..234a43e 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -596,12 +596,12 @@
static inline u32 fnhe_hashfun(__be32 daddr)
{
+ static u32 fnhe_hashrnd __read_mostly;
u32 hval;
- hval = (__force u32) daddr;
- hval ^= (hval >> 11) ^ (hval >> 22);
-
- return hval & (FNHE_HASH_SIZE - 1);
+ net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
+ hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
+ return hash_32(hval, FNHE_HASH_SHIFT);
}
static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
