ipv6: use a stronger hash for tcp
[ Upstream commit 08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664 ]
It looks like its possible to open thousands of TCP IPv6
sessions on a server, all landing in a single slot of TCP hash
table. Incoming packets have to lookup sockets in a very
long list.
We should hash all bits from foreign IPv6 addresses, using
a salt and hash mix, not a simple XOR.
inet6_ehashfn() can also separately use the ports, instead
of xoring them.
Reported-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index e4170a2..12a1bd2 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -15,6 +15,7 @@
#include <linux/ipv6.h>
#include <linux/hardirq.h>
+#include <linux/jhash.h>
#include <net/if_inet6.h>
#include <net/ndisc.h>
#include <net/flow.h>
@@ -390,6 +391,17 @@
void ip6_frag_init(struct inet_frag_queue *q, void *a);
int ip6_frag_match(struct inet_frag_queue *q, void *a);
+/* more secured version of ipv6_addr_hash() */
+static inline u32 ipv6_addr_jhash(const struct in6_addr *a)
+{
+ u32 v = (__force u32)a->s6_addr32[0] ^ (__force u32)a->s6_addr32[1];
+
+ return jhash_3words(v,
+ (__force u32)a->s6_addr32[2],
+ (__force u32)a->s6_addr32[3],
+ ipv6_hash_secret);
+}
+
static inline int ipv6_addr_any(const struct in6_addr *a)
{
return (a->s6_addr32[0] | a->s6_addr32[1] |