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>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9fc08b098ced..dddc6fe90f51 100644
--- 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);