Merge: l2tp: stable backport for 10.2 phase 1

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/1522

JIRA: https://issues.redhat.com/browse/RHEL-115595
Upstream Status: linux.git

Align PPP/L2TP code with upstream.

Signed-off-by: Guillaume Nault <gnault@redhat.com>

Approved-by: Hangbin Liu <haliu@redhat.com>
Approved-by: Paolo Abeni <pabeni@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Scott Weaver <scweaver@redhat.com>

Author: swvrrh

net/l2tp/l2tp_ppp.c

@@ -129,22 +129,12 @@ static const struct ppp_channel_ops pppol2tp_chan_ops = {
 
 static const struct proto_ops pppol2tp_ops;
 
-/* Retrieves the pppol2tp socket associated to a session.
- * A reference is held on the returned socket, so this function must be paired
- * with sock_put().
- */
+/* Retrieves the pppol2tp socket associated to a session. */
 static struct sock *pppol2tp_session_get_sock(struct l2tp_session *session)
 {
 	struct pppol2tp_session *ps = l2tp_session_priv(session);
-	struct sock *sk;
-
-	rcu_read_lock();
-	sk = rcu_dereference(ps->sk);
-	if (sk)
-		sock_hold(sk);
-	rcu_read_unlock();
 
-	return sk;
+	return rcu_dereference(ps->sk);
 }
 
 /* Helpers to obtain tunnel/session contexts from sockets.
@@ -206,14 +196,13 @@ static int pppol2tp_recvmsg(struct socket *sock, struct msghdr *msg,
 
 static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 {
-	struct pppol2tp_session *ps = l2tp_session_priv(session);
-	struct sock *sk = NULL;
+	struct sock *sk;
 
 	/* If the socket is bound, send it in to PPP's input queue. Otherwise
 	 * queue it on the session socket.
 	 */
 	rcu_read_lock();
-	sk = rcu_dereference(ps->sk);
+	sk = pppol2tp_session_get_sock(session);
 	if (!sk)
 		goto no_sock;
 
@@ -510,13 +499,14 @@ static void pppol2tp_show(struct seq_file *m, void *arg)
 	struct l2tp_session *session = arg;
 	struct sock *sk;
 
+	rcu_read_lock();
 	sk = pppol2tp_session_get_sock(session);
 	if (sk) {
 		struct pppox_sock *po = pppox_sk(sk);
 
 		seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
-		sock_put(sk);
 	}
+	rcu_read_unlock();
 }
 
 static void pppol2tp_session_init(struct l2tp_session *session)
@@ -1529,6 +1519,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 		port = ntohs(inet->inet_sport);
 	}
 
+	rcu_read_lock();
 	sk = pppol2tp_session_get_sock(session);
 	if (sk) {
 		state = sk->sk_state;
@@ -1564,8 +1555,8 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 		struct pppox_sock *po = pppox_sk(sk);
 
 		seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
-		sock_put(sk);
 	}
+	rcu_read_unlock();
 }
 
 static int pppol2tp_seq_show(struct seq_file *m, void *v)