net_sched: hold netns refcnt for each action

TC actions have been destroyed asynchronously for a long time,
previously in a RCU callback and now in a workqueue. If we
don't hold a refcnt for its netns, we could use the per netns
data structure, struct tcf_idrinfo, after it has been freed by
netns workqueue.

Hold refcnt to ensure netns destroy happens after all actions
are gone.

Fixes: ddf97ccdd7cb ("net_sched: add network namespace support for tc actions")
Reported-by: Lucas Bates <lucasb@mojatatu.com>
Tested-by: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/act_api.h

@@ -13,6 +13,7 @@
 struct tcf_idrinfo {
 	spinlock_t	lock;
 	struct idr	action_idr;
+	struct net	*net;
 };
 
 struct tc_action_ops;
@@ -104,7 +105,7 @@ struct tc_action_net {
 
 static inline
 int tc_action_net_init(struct tc_action_net *tn,
-		       const struct tc_action_ops *ops)
+		       const struct tc_action_ops *ops, struct net *net)
 {
 	int err = 0;
 
@@ -112,6 +113,7 @@ int tc_action_net_init(struct tc_action_net *tn,
 	if (!tn->idrinfo)
 		return -ENOMEM;
 	tn->ops = ops;
+	tn->idrinfo->net = net;
 	spin_lock_init(&tn->idrinfo->lock);
 	idr_init(&tn->idrinfo->action_idr);
 	return err;

net/sched/act_api.c

@@ -78,6 +78,7 @@ static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p)
 	spin_lock_bh(&idrinfo->lock);
 	idr_remove_ext(&idrinfo->action_idr, p->tcfa_index);
 	spin_unlock_bh(&idrinfo->lock);
+	put_net(idrinfo->net);
 	gen_kill_estimator(&p->tcfa_rate_est);
 	free_tcf(p);
 }
@@ -336,6 +337,7 @@ err3:
 	p->idrinfo = idrinfo;
 	p->ops = ops;
 	INIT_LIST_HEAD(&p->list);
+	get_net(idrinfo->net);
 	*a = p;
 	return 0;
 }

net/sched/act_bpf.c

@@ -398,7 +398,7 @@ static __net_init int bpf_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
 
-	return tc_action_net_init(tn, &act_bpf_ops);
+	return tc_action_net_init(tn, &act_bpf_ops, net);
 }
 
 static void __net_exit bpf_exit_net(struct net *net)

net/sched/act_connmark.c

@@ -206,7 +206,7 @@ static __net_init int connmark_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, connmark_net_id);
 
-	return tc_action_net_init(tn, &act_connmark_ops);
+	return tc_action_net_init(tn, &act_connmark_ops, net);
 }
 
 static void __net_exit connmark_exit_net(struct net *net)

net/sched/act_csum.c

@@ -626,7 +626,7 @@ static __net_init int csum_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, csum_net_id);
 
-	return tc_action_net_init(tn, &act_csum_ops);
+	return tc_action_net_init(tn, &act_csum_ops, net);
 }
 
 static void __net_exit csum_exit_net(struct net *net)

net/sched/act_gact.c

@@ -232,7 +232,7 @@ static __net_init int gact_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, gact_net_id);
 
-	return tc_action_net_init(tn, &act_gact_ops);
+	return tc_action_net_init(tn, &act_gact_ops, net);
 }
 
 static void __net_exit gact_exit_net(struct net *net)

net/sched/act_ife.c

@@ -818,7 +818,7 @@ static __net_init int ife_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, ife_net_id);
 
-	return tc_action_net_init(tn, &act_ife_ops);
+	return tc_action_net_init(tn, &act_ife_ops, net);
 }
 
 static void __net_exit ife_exit_net(struct net *net)

net/sched/act_ipt.c

@@ -334,7 +334,7 @@ static __net_init int ipt_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, ipt_net_id);
 
-	return tc_action_net_init(tn, &act_ipt_ops);
+	return tc_action_net_init(tn, &act_ipt_ops, net);
 }
 
 static void __net_exit ipt_exit_net(struct net *net)
@@ -384,7 +384,7 @@ static __net_init int xt_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, xt_net_id);
 
-	return tc_action_net_init(tn, &act_xt_ops);
+	return tc_action_net_init(tn, &act_xt_ops, net);
 }
 
 static void __net_exit xt_exit_net(struct net *net)

net/sched/act_mirred.c

@@ -343,7 +343,7 @@ static __net_init int mirred_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
 
-	return tc_action_net_init(tn, &act_mirred_ops);
+	return tc_action_net_init(tn, &act_mirred_ops, net);
 }
 
 static void __net_exit mirred_exit_net(struct net *net)

net/sched/act_nat.c

@@ -307,7 +307,7 @@ static __net_init int nat_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, nat_net_id);
 
-	return tc_action_net_init(tn, &act_nat_ops);
+	return tc_action_net_init(tn, &act_nat_ops, net);
 }
 
 static void __net_exit nat_exit_net(struct net *net)

net/sched/act_pedit.c

@@ -450,7 +450,7 @@ static __net_init int pedit_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
 
-	return tc_action_net_init(tn, &act_pedit_ops);
+	return tc_action_net_init(tn, &act_pedit_ops, net);
 }
 
 static void __net_exit pedit_exit_net(struct net *net)

net/sched/act_police.c

@@ -331,7 +331,7 @@ static __net_init int police_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, police_net_id);
 
-	return tc_action_net_init(tn, &act_police_ops);
+	return tc_action_net_init(tn, &act_police_ops, net);
 }
 
 static void __net_exit police_exit_net(struct net *net)

net/sched/act_sample.c

@@ -240,7 +240,7 @@ static __net_init int sample_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, sample_net_id);
 
-	return tc_action_net_init(tn, &act_sample_ops);
+	return tc_action_net_init(tn, &act_sample_ops, net);
 }
 
 static void __net_exit sample_exit_net(struct net *net)

net/sched/act_simple.c

@@ -201,7 +201,7 @@ static __net_init int simp_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, simp_net_id);
 
-	return tc_action_net_init(tn, &act_simp_ops);
+	return tc_action_net_init(tn, &act_simp_ops, net);
 }
 
 static void __net_exit simp_exit_net(struct net *net)

net/sched/act_skbedit.c

@@ -238,7 +238,7 @@ static __net_init int skbedit_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, skbedit_net_id);
 
-	return tc_action_net_init(tn, &act_skbedit_ops);
+	return tc_action_net_init(tn, &act_skbedit_ops, net);
 }
 
 static void __net_exit skbedit_exit_net(struct net *net)

net/sched/act_skbmod.c

@@ -263,7 +263,7 @@ static __net_init int skbmod_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
 
-	return tc_action_net_init(tn, &act_skbmod_ops);
+	return tc_action_net_init(tn, &act_skbmod_ops, net);
 }
 
 static void __net_exit skbmod_exit_net(struct net *net)

net/sched/act_tunnel_key.c

@@ -322,7 +322,7 @@ static __net_init int tunnel_key_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, tunnel_key_net_id);
 
-	return tc_action_net_init(tn, &act_tunnel_key_ops);
+	return tc_action_net_init(tn, &act_tunnel_key_ops, net);
 }
 
 static void __net_exit tunnel_key_exit_net(struct net *net)

net/sched/act_vlan.c

@@ -269,7 +269,7 @@ static __net_init int vlan_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 
-	return tc_action_net_init(tn, &act_vlan_ops);
+	return tc_action_net_init(tn, &act_vlan_ops, net);
 }
 
 static void __net_exit vlan_exit_net(struct net *net)