[ovs-dev] [PATCH 2/2] datapath: add ct_clear action

[Eric Garver]

Upstream commit:
    commit b8226962b1c49c784aeddb9d2fafbf53dfdc2190
    Author: Eric Garver <e at erig.me>
    Date:   Tue Oct 10 16:54:44 2017 -0400

    openvswitch: add ct_clear action

    This adds a ct_clear action for clearing conntrack state. ct_clear is
    currently implemented in OVS userspace, but is not backed by an action
    in the kernel datapath. This is useful for flows that may modify a
    packet tuple after a ct lookup has already occurred.

    Signed-off-by: Eric Garver <e at erig.me>
    Acked-by: Pravin B Shelar <pshelar at ovn.org>
    Signed-off-by: David S. Miller <davem at davemloft.net>

Notes:
   - hunk from include/uapi/linux/openvswitch.h is missing because it
     was added with userspace support in 1fe178d251c8 ("dpif: Add support
     for OVS_ACTION_ATTR_CT_CLEAR")
   - if IP_CT_UNTRACKED is not available use 0 as other nf_ct_set()
     calls do. Since we're setting ct to NULL this is okay.

Signed-off-by: Eric Garver <e at erig.me>
---
 datapath/actions.c      |  4 ++++
 datapath/conntrack.c    | 15 +++++++++++++++
 datapath/conntrack.h    |  7 +++++++
 datapath/flow_netlink.c |  5 +++++
 4 files changed, 31 insertions(+)

diff --git a/datapath/actions.c b/datapath/actions.c
index ad18c2cc768a..1840fe556baf 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -1214,6 +1214,10 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 				return err == -EINPROGRESS ? 0 : err;
 			break;
 
+		case OVS_ACTION_ATTR_CT_CLEAR:
+			err = ovs_ct_clear(skb, key);
+			break;
+
 		case OVS_ACTION_ATTR_PUSH_ETH:
 			err = push_eth(skb, key, nla_data(a));
 			break;
diff --git a/datapath/conntrack.c b/datapath/conntrack.c
index d517a87b0474..3f7943370fb3 100644
--- a/datapath/conntrack.c
+++ b/datapath/conntrack.c
@@ -1170,6 +1170,21 @@ int ovs_ct_execute(struct net *net, struct sk_buff *skb,
 	return err;
 }
 
+int ovs_ct_clear(struct sk_buff *skb, struct sw_flow_key *key)
+{
+	if (skb_nfct(skb)) {
+		nf_conntrack_put(skb_nfct(skb));
+#ifdef HAVE_IP_CT_UNTRACKED
+		nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+#else
+		nf_ct_set(skb, NULL, 0);
+#endif
+		ovs_ct_fill_key(skb, key);
+	}
+
+	return 0;
+}
+
 static int ovs_ct_add_helper(struct ovs_conntrack_info *info, const char *name,
 			     const struct sw_flow_key *key, bool log)
 {
diff --git a/datapath/conntrack.h b/datapath/conntrack.h
index 69ceb80e5a73..0c3964f5bcaf 100644
--- a/datapath/conntrack.h
+++ b/datapath/conntrack.h
@@ -31,6 +31,7 @@ int ovs_ct_action_to_attr(const struct ovs_conntrack_info *, struct sk_buff *);
 
 int ovs_ct_execute(struct net *, struct sk_buff *, struct sw_flow_key *,
 		   const struct ovs_conntrack_info *);
+int ovs_ct_clear(struct sk_buff *skb, struct sw_flow_key *key);
 
 void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key);
 int ovs_ct_put_key(const struct sw_flow_key *swkey,
@@ -74,6 +75,12 @@ static inline int ovs_ct_execute(struct net *net, struct sk_buff *skb,
 	return -ENOTSUPP;
 }
 
+static inline int ovs_ct_clear(struct sk_buff *skb,
+			       struct sw_flow_key *key)
+{
+	return -ENOTSUPP;
+}
+
 static inline void ovs_ct_fill_key(const struct sk_buff *skb,
 				   struct sw_flow_key *key)
 {
diff --git a/datapath/flow_netlink.c b/datapath/flow_netlink.c
index b3b209269dcc..303337c4e99f 100644
--- a/datapath/flow_netlink.c
+++ b/datapath/flow_netlink.c
@@ -77,6 +77,7 @@ static bool actions_may_change_flow(const struct nlattr *actions)
 			break;
 
 		case OVS_ACTION_ATTR_CT:
+		case OVS_ACTION_ATTR_CT_CLEAR:
 		case OVS_ACTION_ATTR_HASH:
 		case OVS_ACTION_ATTR_POP_ETH:
 		case OVS_ACTION_ATTR_POP_MPLS:
@@ -2487,6 +2488,7 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
 			[OVS_ACTION_ATTR_SAMPLE] = (u32)-1,
 			[OVS_ACTION_ATTR_HASH] = sizeof(struct ovs_action_hash),
 			[OVS_ACTION_ATTR_CT] = (u32)-1,
+			[OVS_ACTION_ATTR_CT_CLEAR] = 0,
 			[OVS_ACTION_ATTR_TRUNC] = sizeof(struct ovs_action_trunc),
 			[OVS_ACTION_ATTR_PUSH_ETH] = sizeof(struct ovs_action_push_eth),
 			[OVS_ACTION_ATTR_POP_ETH] = 0,
@@ -2628,6 +2630,9 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
 			skip_copy = true;
 			break;
 
+		case OVS_ACTION_ATTR_CT_CLEAR:
+			break;
+
 		case OVS_ACTION_ATTR_PUSH_ETH:
 			/* Disallow pushing an Ethernet header if one
 			 * is already present */
-- 
2.12.0