Merge branch 'udp-gro-L4'

Paolo Abeni says:

====================
udp: GRO L4 improvements

This series improves the UDP L4 - either 'forward' or 'frag_list' -
co-existence with UDP tunnel GRO, allowing the first to take place
correctly even for encapsulated UDP traffic.

The first for patches are mostly bugfixes, addressing some GRO
edge-cases when both tunnels and L4 are present, enabled and in use.

The next 3 patches avoid unneeded segmentation when UDP GRO
traffic traverses in the receive path UDP tunnels.

Finally, some self-tests are included, covering the relevant
GRO scenarios.

Even if most patches are actually bugfixes, this series is
targeting net-next, as overall it makes available a new feature.

v2 -> v3:
 - no code changes, more verbose commit messages and comment in
   patch 1/8

v1 -> v2:
 - restrict post segmentation csum fixup to the only the relevant pkts
 - use individual 'accept_gso_type' fields instead of whole gso bitmask
   (Willem)
 - use only ipv6 addesses from test range in self-tests (Willem)
 - hopefully clarified most individual patches commit messages
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 42 insertions, 3 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index aa84597bdc33..ae66dadd8543 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -51,7 +51,9 @@ struct udp_sock {
 					   * different encapsulation layer set
 					   * this
 					   */
-			 gro_enabled:1;	/* Can accept GRO packets */
+			 gro_enabled:1,	/* Request GRO aggregation */
+			 accept_udp_l4:1,
+			 accept_udp_fraglist:1;
 	/*
 	 * Following member retains the information to create a UDP header
 	 * when the socket is uncorked.
@@ -131,8 +133,22 @@ static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,
 
 static inline bool udp_unexpected_gso(struct sock *sk, struct sk_buff *skb)
 {
-	return !udp_sk(sk)->gro_enabled && skb_is_gso(skb) &&
-	       skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4;
+	if (!skb_is_gso(skb))
+		return false;
+
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && !udp_sk(sk)->accept_udp_l4)
+		return true;
+
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST && !udp_sk(sk)->accept_udp_fraglist)
+		return true;
+
+	return false;
+}
+
+static inline void udp_allow_gso(struct sock *sk)
+{
+	udp_sk(sk)->accept_udp_l4 = 1;
+	udp_sk(sk)->accept_udp_fraglist = 1;
 }
 
 #define udp_portaddr_for_each_entry(__sk, list) \
diff --git a/include/net/udp.h b/include/net/udp.h
index d4d064c59232..adf2ff8ac87c 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -515,6 +515,29 @@ static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
 	return segs;
 }
 
+static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
+{
+	/* UDP-lite can't land here - no GRO */
+	WARN_ON_ONCE(UDP_SKB_CB(skb)->partial_cov);
+
+	/* UDP packets generated with UDP_SEGMENT and traversing:
+	 *
+	 * UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx)
+	 *
+	 * can reach an UDP socket with CHECKSUM_NONE, because
+	 * __iptunnel_pull_header() converts CHECKSUM_PARTIAL into NONE.
+	 * SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets with no UDP tunnel will
+	 * have a valid checksum, as the GRO engine validates the UDP csum
+	 * before the aggregation and nobody strips such info in between.
+	 * Instead of adding another check in the tunnel fastpath, we can force
+	 * a valid csum after the segmentation.
+	 * Additionally fixup the UDP CB.
+	 */
+	UDP_SKB_CB(skb)->cscov = skb->len;
+	if (skb->ip_summed == CHECKSUM_NONE && !skb->csum_valid)
+		skb->csum_valid = 1;
+}
+
 #ifdef CONFIG_BPF_SYSCALL
 struct sk_psock;
 struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);