inet: convert inet_ehash_secret and ipv6_hash_secret to net_get_random_once

Initialize the ehash and ipv6_hash_secrets with net_get_random_once.

Each compilation unit gets its own secret now:
  ipv4/inet_hashtables.o
  ipv4/udp.o
  ipv6/inet6_hashtables.o
  ipv6/udp.o
  rds/connection.o

The functions still get inlined into the hashing functions. In the fast
path we have at most two (needed in ipv6) if (unlikely(...)).

Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 3 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 324bd36..44fc4e3 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -59,10 +59,21 @@ static unsigned int udp6_ehashfn(struct net *net,
 				  const struct in6_addr *faddr,
 				  const __be16 fport)
 {
-	const u32 lhash = (__force u32)laddr->s6_addr32[3];
-	const u32 fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
+	static u32 udp6_ehash_secret __read_mostly;
+	static u32 udp_ipv6_hash_secret __read_mostly;
+
+	u32 lhash, fhash;
+
+	net_get_random_once(&udp6_ehash_secret,
+			    sizeof(udp6_ehash_secret));
+	net_get_random_once(&udp_ipv6_hash_secret,
+			    sizeof(udp_ipv6_hash_secret));
+
+	lhash = (__force u32)laddr->s6_addr32[3];
+	fhash = __ipv6_addr_jhash(faddr, udp_ipv6_hash_secret);
+
 	return __inet6_ehashfn(lhash, lport, fhash, fport,
-			       inet_ehash_secret + net_hash_mix(net));
+			       udp_ipv6_hash_secret + net_hash_mix(net));
 }
 
 int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)