Merge l2-mtd/next into l2-mtd/master

1 files changed, 29 insertions, 0 deletions

diff --git a/include/net/udp.h b/include/net/udp.h
index 68a1fefe3dfe..70f941368ace 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -176,6 +176,35 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
 		     int (*)(const struct sock *, const struct sock *),
 		     unsigned int hash2_nulladdr);
 
+static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
+				       int min, int max, bool use_eth)
+{
+	u32 hash;
+
+	if (min >= max) {
+		/* Use default range */
+		inet_get_local_port_range(net, &min, &max);
+	}
+
+	hash = skb_get_hash(skb);
+	if (unlikely(!hash) && use_eth) {
+		/* Can't find a normal hash, caller has indicated an Ethernet
+		 * packet so use that to compute a hash.
+		 */
+		hash = jhash(skb->data, 2 * ETH_ALEN,
+			     (__force u32) skb->protocol);
+	}
+
+	/* Since this is being sent on the wire obfuscate hash a bit
+	 * to minimize possbility that any useful information to an
+	 * attacker is leaked. Only upper 16 bits are relevant in the
+	 * computation for 16 bit port value.
+	 */
+	hash ^= hash << 16;
+
+	return htons((((u64) hash * (max - min)) >> 32) + min);
+}
+
 /* net/ipv4/udp.c */
 void udp_v4_early_demux(struct sk_buff *skb);
 int udp_get_port(struct sock *sk, unsigned short snum,