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ipv4: harden fnhe_hashfun()

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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>
This commit is contained in:
Eric Dumazet 2014-09-04 08:21:31 -07:00 committed by David S. Miller
parent 18a47e6d8a
commit d546c62154
2 changed files with 6 additions and 5 deletions
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3
include/net/ip_fib.h
View File

@ -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 {

8
net/ipv4/route.c
View File

@ -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)