netfilter: conntrack: switch to siphash

Replace jhash in conntrack and nat core with siphash.

While at it, use the netns mix value as part of the input key
rather than abuse the seed value.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 14 insertions, 4 deletions

diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 7de595ead06a..7008961f5cb0 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -13,7 +13,7 @@
 #include <linux/skbuff.h>
 #include <linux/gfp.h>
 #include <net/xfrm.h>
-#include <linux/jhash.h>
+#include <linux/siphash.h>
 #include <linux/rtnetlink.h>
 
 #include <net/netfilter/nf_conntrack.h>
@@ -34,7 +34,7 @@ static unsigned int nat_net_id __read_mostly;
 
 static struct hlist_head *nf_nat_bysource __read_mostly;
 static unsigned int nf_nat_htable_size __read_mostly;
-static unsigned int nf_nat_hash_rnd __read_mostly;
+static siphash_key_t nf_nat_hash_rnd __read_mostly;
 
 struct nf_nat_lookup_hook_priv {
 	struct nf_hook_entries __rcu *entries;
@@ -153,12 +153,22 @@ static unsigned int
 hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
 {
 	unsigned int hash;
+	struct {
+		struct nf_conntrack_man src;
+		u32 net_mix;
+		u32 protonum;
+	} __aligned(SIPHASH_ALIGNMENT) combined;
 
 	get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
 
+	memset(&combined, 0, sizeof(combined));
+
 	/* Original src, to ensure we map it consistently if poss. */
-	hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
-		      tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
+	combined.src = tuple->src;
+	combined.net_mix = net_hash_mix(n);
+	combined.protonum = tuple->dst.protonum;
+
+	hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd);
 
 	return reciprocal_scale(hash, nf_nat_htable_size);
 }