openvswitch: Serialize acts with original netlink len

Previously, we used the kernel-internal netlink actions length to
calculate the size of messages to serialize back to userspace.
However,the sw_flow_actions may not be formatted exactly the same as the
actions on the wire, so store the original actions length when
de-serializing and re-use the original length when serializing.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/datapath.c

@@ -713,7 +713,7 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts,
 
 	/* OVS_FLOW_ATTR_ACTIONS */
 	if (should_fill_actions(ufid_flags))
-		len += nla_total_size(acts->actions_len);
+		len += nla_total_size(acts->orig_len);
 
 	return len
 		+ nla_total_size(sizeof(struct ovs_flow_stats)) /* OVS_FLOW_ATTR_STATS */

net/openvswitch/flow.h

@@ -144,6 +144,7 @@ struct sw_flow_id {
 
 struct sw_flow_actions {
 	struct rcu_head rcu;
+	size_t orig_len;	/* From flow_cmd_new netlink actions size */
 	u32 actions_len;
 	struct nlattr actions[];
 };

net/openvswitch/flow_netlink.c

@@ -1619,6 +1619,7 @@ static struct nlattr *reserve_sfa_size(struct sw_flow_actions **sfa,
 
 	memcpy(acts->actions, (*sfa)->actions, (*sfa)->actions_len);
 	acts->actions_len = (*sfa)->actions_len;
+	acts->orig_len = (*sfa)->orig_len;
 	kfree(*sfa);
 	*sfa = acts;
 
@@ -2223,6 +2224,7 @@ int ovs_nla_copy_actions(const struct nlattr *attr,
 	if (IS_ERR(*sfa))
 		return PTR_ERR(*sfa);
 
+	(*sfa)->orig_len = nla_len(attr);
 	err = __ovs_nla_copy_actions(attr, key, 0, sfa, key->eth.type,
 				     key->eth.tci, log);
 	if (err)