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-rw-r--r--include/net/udp.h29
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,