linux-kernel - [PATCH 3.2 16/79] l2tp: push all ppp pseudowire shutdown through .release handler

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Message-ID: <lsq.1518322806.819702711@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Tom Parkin" <tparkin@...alix.com>,
        "David S. Miller" <davem@...emloft.net>,
        "James Chapman" <jchapman@...alix.com>
Subject: [PATCH 3.2 16/79] l2tp: push all ppp pseudowire shutdown through
 .release handler

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Parkin <tparkin@...alix.com>

commit cf2f5c886a209377daefd5d2ba0bcd49c3887813 upstream.

If userspace deletes a ppp pseudowire using the netlink API, either by
directly deleting the session or by deleting the tunnel that contains the
session, we need to tear down the corresponding pppox channel.

Rather than trying to manage two pppox unbind codepaths, switch the netlink
and l2tp_core session_close handlers to close via. the l2tp_ppp socket
.release handler.

Signed-off-by: Tom Parkin <tparkin@...alix.com>
Signed-off-by: James Chapman <jchapman@...alix.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/l2tp/l2tp_ppp.c | 53 ++++++++++-------------------------------------------
 1 file changed, 10 insertions(+), 43 deletions(-)

--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -95,6 +95,7 @@
 #include <net/ip.h>
 #include <net/udp.h>
 #include <net/xfrm.h>
+#include <net/inet_common.h>
 
 #include <asm/byteorder.h>
 #include <linux/atomic.h>
@@ -460,34 +461,16 @@ static void pppol2tp_session_close(struc
 {
 	struct pppol2tp_session *ps = l2tp_session_priv(session);
 	struct sock *sk = ps->sock;
-	struct sk_buff *skb;
+	struct socket *sock = sk->sk_socket;
 
 	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 
-	if (session->session_id == 0)
-		goto out;
-
-	if (sk != NULL) {
-		lock_sock(sk);
-
-		if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
-			pppox_unbind_sock(sk);
-			sk->sk_state = PPPOX_DEAD;
-			sk->sk_state_change(sk);
-		}
-
-		/* Purge any queued data */
-		skb_queue_purge(&sk->sk_receive_queue);
-		skb_queue_purge(&sk->sk_write_queue);
-		while ((skb = skb_dequeue(&session->reorder_q))) {
-			kfree_skb(skb);
-			sock_put(sk);
-		}
 
-		release_sock(sk);
+	if (sock) {
+		inet_shutdown(sock, 2);
+		/* Don't let the session go away before our socket does */
+		l2tp_session_inc_refcount(session);
 	}
-
-out:
 	return;
 }
 
@@ -538,16 +521,12 @@ static int pppol2tp_release(struct socke
 	session = pppol2tp_sock_to_session(sk);
 
 	/* Purge any queued data */
-	skb_queue_purge(&sk->sk_receive_queue);
-	skb_queue_purge(&sk->sk_write_queue);
 	if (session != NULL) {
-		struct sk_buff *skb;
-		while ((skb = skb_dequeue(&session->reorder_q))) {
-			kfree_skb(skb);
-			sock_put(sk);
-		}
+		l2tp_session_queue_purge(session);
 		sock_put(sk);
 	}
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
 
 	release_sock(sk);
 
@@ -872,18 +851,6 @@ out:
 	return error;
 }
 
-/* Called when deleting sessions via the netlink interface.
- */
-static int pppol2tp_session_delete(struct l2tp_session *session)
-{
-	struct pppol2tp_session *ps = l2tp_session_priv(session);
-
-	if (ps->sock == NULL)
-		l2tp_session_dec_refcount(session);
-
-	return 0;
-}
-
 #endif /* CONFIG_L2TP_V3 */
 
 /* getname() support.
@@ -1801,7 +1768,7 @@ static const struct pppox_proto pppol2tp
 
 static const struct l2tp_nl_cmd_ops pppol2tp_nl_cmd_ops = {
 	.session_create	= pppol2tp_session_create,
-	.session_delete	= pppol2tp_session_delete,
+	.session_delete	= l2tp_session_delete,
 };
 
 #endif /* CONFIG_L2TP_V3 */