net: sched: copy tunnel info when setting flow_action entry->tunnel

In order to remove dependency on rtnl lock, modify tc_setup_flow_action()
to copy tunnel info, instead of just saving pointer to tunnel_key action
tunnel info. This is necessary to prevent concurrent action overwrite from
releasing tunnel info while it is being used by rtnl-unlocked driver.

Implement helper tcf_tunnel_info_copy() that is used to copy tunnel info
with all its options to dynamically allocated memory block. Modify
tc_cleanup_flow_action() to free dynamically allocated tunnel info.
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tc_act/tc_tunnel_key.h

@@ -59,4 +59,21 @@ static inline struct ip_tunnel_info *tcf_tunnel_info(const struct tc_action *a)
 	return NULL;
 #endif
 }
+
+static inline struct ip_tunnel_info *
+tcf_tunnel_info_copy(const struct tc_action *a)
+{
+#ifdef CONFIG_NET_CLS_ACT
+	struct ip_tunnel_info *tun = tcf_tunnel_info(a);
+
+	if (tun) {
+		size_t tun_size = sizeof(*tun) + tun->options_len;
+		struct ip_tunnel_info *tun_copy = kmemdup(tun, tun_size,
+							  GFP_KERNEL);
+
+		return tun_copy;
+	}
+#endif
+	return NULL;
+}
 #endif /* __NET_TC_TUNNEL_KEY_H */

net/sched/cls_api.c

@@ -3279,6 +3279,9 @@ void tc_cleanup_flow_action(struct flow_action *flow_action)
 			if (entry->dev)
 				dev_put(entry->dev);
 			break;
+		case FLOW_ACTION_TUNNEL_ENCAP:
+			kfree(entry->tunnel);
+			break;
 		default:
 			break;
 		}
@@ -3355,7 +3358,11 @@ int tc_setup_flow_action(struct flow_action *flow_action,
 			}
 		} else if (is_tcf_tunnel_set(act)) {
 			entry->id = FLOW_ACTION_TUNNEL_ENCAP;
-			entry->tunnel = tcf_tunnel_info(act);
+			entry->tunnel = tcf_tunnel_info_copy(act);
+			if (!entry->tunnel) {
+				err = -ENOMEM;
+				goto err_out;
+			}
 		} else if (is_tcf_tunnel_release(act)) {
 			entry->id = FLOW_ACTION_TUNNEL_DECAP;
 		} else if (is_tcf_pedit(act)) {