udp: add support for UDP_GRO cmsg

When UDP GRO is enabled, the UDP_GRO cmsg will carry the ingress
datagram size. User-space can use such info to compute the original
packets layout.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/udp.h b/include/linux/udp.h
index f613b32..e23d502 100644 (file)
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -121,6 +121,17 @@ static inline bool udp_get_no_check6_rx(struct sock *sk)
        return udp_sk(sk)->no_check6_rx;
 }
 
+static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,
+                                struct sk_buff *skb)
+{
+       int gso_size;
+
+       if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) {
+               gso_size = skb_shinfo(skb)->gso_size;
+               put_cmsg(msg, SOL_UDP, UDP_GRO, sizeof(gso_size), &gso_size);
+       }
+}
+
 #define udp_portaddr_for_each_entry(__sk, list) \
        hlist_for_each_entry(__sk, list, __sk_common.skc_portaddr_node)
 

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9fc08b0..dddc6fe 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1711,6 +1711,10 @@ try_again:
                memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
                *addr_len = sizeof(*sin);
        }
+
+       if (udp_sk(sk)->gro_enabled)
+               udp_cmsg_recv(msg, sk, skb);
+
        if (inet->cmsg_flags)
                ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
 

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index bdf7e07..4c79dc5 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -417,6 +417,9 @@ try_again:
                *addr_len = sizeof(*sin6);
        }
 
+       if (udp_sk(sk)->gro_enabled)
+               udp_cmsg_recv(msg, sk, skb);
+
        if (np->rxopt.all)
                ip6_datagram_recv_common_ctl(sk, msg, skb);