Commit d546c621 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv4: harden fnhe_hashfun() 



Lets make this hash function a bit secure, as ICMP attacks are still
in the wild.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 18a47e6d

include/net/ip_fib.h

+2 −1
Original line number Diff line number Diff line
@@ -65,7 +65,8 @@ struct fnhe_hash_bucket { 
	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 {

net/ipv4/route.c

+4 −4
Original line number Diff line number Diff line
@@ -596,12 +596,12 @@ static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash) 


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)