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| author | Eric Dumazet <edumazet@google.com> | 2014-09-04 17:21:31 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-06 02:40:33 +0200 |
| commit | d546c621542df9e45eedc91f35356e887ac63b7b (patch) | |
| tree | bcf28df1dafdf743cdbad9230986a5a413e08a26 | |
| parent | net-timestamp: fix allocation error in test (diff) | |
| download | linux-d546c621542df9e45eedc91f35356e887ac63b7b.tar.xz linux-d546c621542df9e45eedc91f35356e887ac63b7b.zip | |
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>
| -rw-r--r-- | include/net/ip_fib.h | 3 | ||||
| -rw-r--r-- | net/ipv4/route.c | 8 |
2 files changed, 6 insertions, 5 deletions
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index f30fd554127e..dc9d2a27c315 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -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 { diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 44b0cbdd76f1..234a43e233dc 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -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) |