Merge branch 'gtp-fix-several-bugs'

Taehee Yoo says:

====================
gtp: fix several bugs

This patch series fixes several bugs in the gtp module.

First patch fixes suspicious RCU usage.
The problem is to use rcu_dereference_sk_user_data() outside of
RCU read critical section.

Second patch fixes use-after-free.
gtp_encap_destroy() is called twice.
gtp_encap_destroy() use both gtp->sk0 and gtp->sk1u.
these pointers can be freed in gtp_encap_destroy().
So, gtp_encap_destroy() should avoid using freed sk pointer.

Third patch removes duplicate code in gtp_dellink().
gtp_dellink() calls gtp_encap_disable() twice.
So, remove one of them.

Fourth patch fixes usage of GFP_KERNEL.
GFP_KERNEL can not be used in RCU read critical section.
This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL.

Fifth patch fixes use-after-free in gtp_newlink().
gtp_newlink() uses gtp_net which would be destroyed by the __exit_net
routine.
So, gtp_newlink should not be called after the __exit_net routine.

Sixth patch adds missing error handling routine in gtp_encap_enable().
gtp_encap_enable() will fail, if invalid role value is sent from
user-space. if so, gtp_encap_enable() should execute error handling
routine.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/gtp.c

@@ -285,16 +285,29 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
 	return gtp_rx(pctx, skb, hdrlen, gtp->role);
 }
 
-static void gtp_encap_destroy(struct sock *sk)
+static void __gtp_encap_destroy(struct sock *sk)
 {
 	struct gtp_dev *gtp;
 
-	gtp = rcu_dereference_sk_user_data(sk);
+	lock_sock(sk);
+	gtp = sk->sk_user_data;
 	if (gtp) {
+		if (gtp->sk0 == sk)
+			gtp->sk0 = NULL;
+		else
+			gtp->sk1u = NULL;
 		udp_sk(sk)->encap_type = 0;
 		rcu_assign_sk_user_data(sk, NULL);
 		sock_put(sk);
 	}
+	release_sock(sk);
+}
+
+static void gtp_encap_destroy(struct sock *sk)
+{
+	rtnl_lock();
+	__gtp_encap_destroy(sk);
+	rtnl_unlock();
 }
 
 static void gtp_encap_disable_sock(struct sock *sk)
@@ -302,7 +315,7 @@ static void gtp_encap_disable_sock(struct sock *sk)
 	if (!sk)
 		return;
 
-	gtp_encap_destroy(sk);
+	__gtp_encap_destroy(sk);
 }
 
 static void gtp_encap_disable(struct gtp_dev *gtp)
@@ -681,7 +694,6 @@ static void gtp_dellink(struct net_device *dev, struct list_head *head)
 {
 	struct gtp_dev *gtp = netdev_priv(dev);
 
-	gtp_encap_disable(gtp);
 	gtp_hashtable_free(gtp);
 	list_del_rcu(&gtp->list);
 	unregister_netdevice_queue(dev, head);
@@ -796,7 +808,8 @@ static struct sock *gtp_encap_enable_socket(int fd, int type,
 		goto out_sock;
 	}
 
-	if (rcu_dereference_sk_user_data(sock->sk)) {
+	lock_sock(sock->sk);
+	if (sock->sk->sk_user_data) {
 		sk = ERR_PTR(-EBUSY);
 		goto out_sock;
 	}
@@ -812,6 +825,7 @@ static struct sock *gtp_encap_enable_socket(int fd, int type,
 	setup_udp_tunnel_sock(sock_net(sock->sk), sock, &tuncfg);
 
 out_sock:
+	release_sock(sock->sk);
 	sockfd_put(sock);
 	return sk;
 }
@@ -843,9 +857,14 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[])
 
 	if (data[IFLA_GTP_ROLE]) {
 		role = nla_get_u32(data[IFLA_GTP_ROLE]);
-		if (role > GTP_ROLE_SGSN)
+		if (role > GTP_ROLE_SGSN) {
+			if (sk0)
+				gtp_encap_disable_sock(sk0);
+			if (sk1u)
+				gtp_encap_disable_sock(sk1u);
 			return -EINVAL;
 		}
+	}
 
 	gtp->sk0 = sk0;
 	gtp->sk1u = sk1u;
@@ -945,7 +964,7 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock *sk,
 
 	}
 
-	pctx = kmalloc(sizeof(struct pdp_ctx), GFP_KERNEL);
+	pctx = kmalloc(sizeof(*pctx), GFP_ATOMIC);
 	if (pctx == NULL)
 		return -ENOMEM;
 
@@ -1034,6 +1053,7 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info)
 		return -EINVAL;
 	}
 
+	rtnl_lock();
 	rcu_read_lock();
 
 	gtp = gtp_find_dev(sock_net(skb->sk), info->attrs);
@@ -1058,6 +1078,7 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info)
 
 out_unlock:
 	rcu_read_unlock();
+	rtnl_unlock();
 	return err;
 }
 
@@ -1360,9 +1381,9 @@ late_initcall(gtp_init);
 
 static void __exit gtp_fini(void)
 {
-	unregister_pernet_subsys(&gtp_net_ops);
 	genl_unregister_family(&gtp_genl_family);
 	rtnl_link_unregister(&gtp_link_ops);
+	unregister_pernet_subsys(&gtp_net_ops);
 
 	pr_info("GTP module unloaded\n");
 }