l2tp: avoid using ->tunnel_sock for getting session's parent tunnel

Sessions don't need to use l2tp_sock_to_tunnel(xxx->tunnel_sock) for
accessing their parent tunnel. They have the .tunnel field in the
l2tp_session structure for that. Furthermore, in all these cases, the
session is registered, so we're guaranteed that .tunnel isn't NULL and
that the session properly holds a reference on the tunnel.
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ppp.c

@@ -295,7 +295,6 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 	int error;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
-	struct pppol2tp_session *ps;
 	int uhlen;
 
 	error = -ENOTCONN;
@@ -308,10 +307,7 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 	if (session == NULL)
 		goto error;
 
-	ps = l2tp_session_priv(session);
-	tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
-	if (tunnel == NULL)
-		goto error_put_sess;
+	tunnel = session->tunnel;
 
 	uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
 
@@ -322,7 +318,7 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 			   2 + total_len, /* 2 bytes for PPP_ALLSTATIONS & PPP_UI */
 			   0, GFP_KERNEL);
 	if (!skb)
-		goto error_put_sess_tun;
+		goto error_put_sess;
 
 	/* Reserve space for headers. */
 	skb_reserve(skb, NET_SKB_PAD);
@@ -340,20 +336,17 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 	error = memcpy_from_msg(skb_put(skb, total_len), m, total_len);
 	if (error < 0) {
 		kfree_skb(skb);
-		goto error_put_sess_tun;
+		goto error_put_sess;
 	}
 
 	local_bh_disable();
 	l2tp_xmit_skb(session, skb, session->hdr_len);
 	local_bh_enable();
 
-	sock_put(ps->tunnel_sock);
 	sock_put(sk);
 
 	return total_len;
 
-error_put_sess_tun:
-	sock_put(ps->tunnel_sock);
 error_put_sess:
 	sock_put(sk);
 error:
@@ -377,10 +370,8 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 {
 	struct sock *sk = (struct sock *) chan->private;
-	struct sock *sk_tun;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
-	struct pppol2tp_session *ps;
 	int uhlen, headroom;
 
 	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
@@ -391,13 +382,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 	if (session == NULL)
 		goto abort;
 
-	ps = l2tp_session_priv(session);
-	sk_tun = ps->tunnel_sock;
-	if (sk_tun == NULL)
-		goto abort_put_sess;
-	tunnel = l2tp_sock_to_tunnel(sk_tun);
-	if (tunnel == NULL)
-		goto abort_put_sess;
+	tunnel = session->tunnel;
 
 	uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
 	headroom = NET_SKB_PAD +
@@ -406,7 +391,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 		   session->hdr_len +	/* L2TP header */
 		   2;			/* 2 bytes for PPP_ALLSTATIONS & PPP_UI */
 	if (skb_cow_head(skb, headroom))
-		goto abort_put_sess_tun;
+		goto abort_put_sess;
 
 	/* Setup PPP header */
 	__skb_push(skb, 2);
@@ -417,12 +402,10 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 	l2tp_xmit_skb(session, skb, session->hdr_len);
 	local_bh_enable();
 
-	sock_put(sk_tun);
 	sock_put(sk);
+
 	return 1;
 
-abort_put_sess_tun:
-	sock_put(sk_tun);
 abort_put_sess:
 	sock_put(sk);
 abort:
@@ -919,9 +902,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 		goto end;
 
 	pls = l2tp_session_priv(session);
-	tunnel = l2tp_sock_to_tunnel(pls->tunnel_sock);
-	if (tunnel == NULL)
-		goto end_put_sess;
+	tunnel = session->tunnel;
 
 	inet = inet_sk(tunnel->sock);
 	if ((tunnel->version == 2) && (tunnel->sock->sk_family == AF_INET)) {
@@ -1001,8 +982,6 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 	*usockaddr_len = len;
 	error = 0;
 
-	sock_put(pls->tunnel_sock);
-end_put_sess:
 	sock_put(sk);
 end:
 	return error;
@@ -1241,7 +1220,6 @@ static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
 	struct sock *sk = sock->sk;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
-	struct pppol2tp_session *ps;
 	int err;
 
 	if (!sk)
@@ -1265,16 +1243,10 @@ static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
 	/* Special case: if session's session_id is zero, treat ioctl as a
 	 * tunnel ioctl
 	 */
-	ps = l2tp_session_priv(session);
 	if ((session->session_id == 0) &&
 	    (session->peer_session_id == 0)) {
-		err = -EBADF;
-		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
+		tunnel = session->tunnel;
 		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
-		sock_put(ps->tunnel_sock);
 		goto end_put_sess;
 	}
 
@@ -1400,7 +1372,6 @@ static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
 	struct sock *sk = sock->sk;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
-	struct pppol2tp_session *ps;
 	int val;
 	int err;
 
@@ -1425,20 +1396,14 @@ static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
 
 	/* Special case: if session_id == 0x0000, treat as operation on tunnel
 	 */
-	ps = l2tp_session_priv(session);
 	if ((session->session_id == 0) &&
 	    (session->peer_session_id == 0)) {
-		err = -EBADF;
-		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
+		tunnel = session->tunnel;
 		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
-		sock_put(ps->tunnel_sock);
-	} else
+	} else {
 		err = pppol2tp_session_setsockopt(sk, session, optname, val);
+	}
 
-end_put_sess:
 	sock_put(sk);
 end:
 	return err;
@@ -1526,7 +1491,6 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
 	struct l2tp_tunnel *tunnel;
 	int val, len;
 	int err;
-	struct pppol2tp_session *ps;
 
 	if (level != SOL_PPPOL2TP)
 		return -EINVAL;
@@ -1550,16 +1514,10 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
 		goto end;
 
 	/* Special case: if session_id == 0x0000, treat as operation on tunnel */
-	ps = l2tp_session_priv(session);
 	if ((session->session_id == 0) &&
 	    (session->peer_session_id == 0)) {
-		err = -EBADF;
-		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
+		tunnel = session->tunnel;
 		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
-		sock_put(ps->tunnel_sock);
 		if (err)
 			goto end_put_sess;
 	} else {