Subject: [PATCH 19/26] net/sched: act_ct: fix miss set mru for ovs after defrag in act_ct

From: wenxu <[email-masked]>
Date: Fri, 31 Jul 2020 10:45:01 +0800

[ Upstream commit 038ebb1a713d114d54dbf14868a73181c0c92758 ]

When openvswitch conntrack offload with act_ct action. Fragment packets
defrag in the ingress tc act_ct action and miss the next chain. Then the
packet pass to the openvswitch datapath without the mru. The over
mtu packet will be dropped in output action in openvswitch for over mtu.

"kernel: net2: dropped over-mtu packet: 1528 > 1500"

This patch add mru in the tc_skb_ext for adefrag and miss next chain
situation. And also add mru in the qdisc_skb_cb. The act_ct set the mru
to the qdisc_skb_cb when the packet defrag. And When the chain miss,
The mru is set to tc_skb_ext which can be got by ovs datapath.

Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
Signed-off-by: wenxu <[email-masked]>
Reviewed-by: Cong Wang <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 include/linux/skbuff.h    | 1 +
 include/net/sch_generic.h | 3 ++-
 net/openvswitch/flow.c    | 1 +
 net/sched/act_ct.c        | 8 ++++++--
 net/sched/cls_api.c       | 1 +
 5 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 7e737a94bc63..7f348591647a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -283,6 +283,7 @@ struct nf_bridge_info {
  */
 struct tc_skb_ext {
 	__u32 chain;
+	__u16 mru;
 };
 #endif
 
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 8428aa614265..f6bcd3960ba8 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -380,6 +380,7 @@ struct qdisc_skb_cb {
 	};
 #define QDISC_CB_PRIV_LEN 20
 	unsigned char		data[QDISC_CB_PRIV_LEN];
+	u16			mru;
 };
 
 typedef void tcf_chain_head_change_t(struct tcf_proto *tp_head, void *priv);
@@ -459,7 +460,7 @@ static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
 {
 	struct qdisc_skb_cb *qcb;
 
-	BUILD_BUG_ON(sizeof(skb->cb) < offsetof(struct qdisc_skb_cb, data) + sz);
+	BUILD_BUG_ON(sizeof(skb->cb) < sizeof(*qcb));
 	BUILD_BUG_ON(sizeof(qcb->data) < sz);
 }
 
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 9d375e74b607..03942c30d83e 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -890,6 +890,7 @@ int ovs_flow_key_extract(const struct ip_tunnel_info *tun_info,
 	if (static_branch_unlikely(&tc_recirc_sharing_support)) {
 		tc_ext = skb_ext_find(skb, TC_SKB_EXT);
 		key->recirc_id = tc_ext ? tc_ext->chain : 0;
+		OVS_CB(skb)->mru = tc_ext ? tc_ext->mru : 0;
 	} else {
 		key->recirc_id = 0;
 	}
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index e191f2728389..417526d7741b 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -704,8 +704,10 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
 		if (err && err != -EINPROGRESS)
 			goto out_free;
 
-		if (!err)
+		if (!err) {
 			*defrag = true;
+			cb.mru = IPCB(skb)->frag_max_size;
+		}
 	} else { /* NFPROTO_IPV6 */
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
@@ -715,8 +717,10 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
 		if (err && err != -EINPROGRESS)
 			goto out_free;
 
-		if (!err)
+		if (!err) {
 			*defrag = true;
+			cb.mru = IP6CB(skb)->frag_max_size;
+		}
 #else
 		err = -EOPNOTSUPP;
 		goto out_free;
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 58d469a66896..2ef39483a8bb 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1679,6 +1679,7 @@ int tcf_classify_ingress(struct sk_buff *skb,
 		if (WARN_ON_ONCE(!ext))
 			return TC_ACT_SHOT;
 		ext->chain = last_executed_chain;
+		ext->mru = qdisc_skb_cb(skb)->mru;
 	}
 
 	return ret;
-- 
2.26.2