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| -rw-r--r-- | include/net/udp.h | 29 |
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, |