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 <pab...@redhat.com> --- include/linux/udp.h | 11 +++++++++++ net/ipv4/udp.c | 4 ++++ net/ipv6/udp.c | 3 +++ 3 files changed, 18 insertions(+) diff --git a/include/linux/udp.h b/include/linux/udp.h index f613b329852e..e23d5024f42f 100644 --- 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 0d447fd194c5..725ece9d78af 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1714,6 +1714,10 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock, 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 fc0ce6c59ebb..8e76e719305c 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -421,6 +421,9 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, *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); -- 2.17.2