[PATCH can-next v2 2/3] af_can: store socket pointers in struct netns_can

AF_CAN sockets need to be stored in the netns_can structure
in order to be retrieved by the CAN diagnostic module when
a netlink request message is issued by the userspace.

On socket creation (`can_create()`), add the pointer to the
new socket to `netns_can::sk_list`. During socket release
(`isotp_release()`, `raw_release()`, `j1939_release()`,
`bcm_release()`), remove the corresponding pointer from
this list.

Since this is a prerequisite of the CAN diagnostic module,
deletes and insert operations are conditioned by
IS_ENABLED(CONFIG_CAN_DIAG).

Signed-off-by: Filippo Storniolo <[email protected]>
---
 include/linux/can/core.h | 11 +++++++++++
 include/net/netns/can.h  |  6 ++++++
 net/can/af_can.c         | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/can/bcm.c            |  2 ++
 net/can/isotp.c          |  2 ++
 net/can/j1939/socket.c   |  2 ++
 net/can/raw.c            |  2 ++
 7 files changed, 75 insertions(+)

diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 3287232e3cad..5132f5c89b7c 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -61,4 +61,15 @@ extern int can_send(struct sk_buff *skb, int loop);
 void can_set_skb_uid(struct sk_buff *skb);
 void can_sock_destruct(struct sock *sk);
 
+/* function prototypes for the CAN diag module */
+#if IS_ENABLED(CONFIG_CAN_DIAG)
+void lock_can_diag_mutex(struct net *net);
+void unlock_can_diag_mutex(struct net *net);
+void can_add_sock_sklist(struct sock *sk);
+void can_remove_sock_sklist(struct sock *sk);
+#else
+#define can_add_sock_sklist(sk)
+#define can_remove_sock_sklist(sk)
+#endif
+
 #endif /* !_CAN_CORE_H */
diff --git a/include/net/netns/can.h b/include/net/netns/can.h
index 48b79f7e6236..bcafff5e6669 100644
--- a/include/net/netns/can.h
+++ b/include/net/netns/can.h
@@ -36,6 +36,12 @@ struct netns_can {
 
 	/* CAN GW per-net gateway jobs */
 	struct hlist_head cgw_list;
+
+#if IS_ENABLED(CONFIG_CAN_DIAG)
+	/* CAN diag support */
+	struct mutex		sklist_lock;
+	struct hlist_head	sklist;
+#endif
 };
 
 #endif /* __NETNS_CAN_H__ */
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 65af25946985..1ea36411f219 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -111,6 +111,44 @@ static inline void can_put_proto(const struct can_proto *cp)
 	module_put(cp->prot->owner);
 }
 
+#if IS_ENABLED(CONFIG_CAN_DIAG)
+void lock_can_diag_mutex(struct net *net)
+{
+	mutex_lock(&net->can.sklist_lock);
+}
+EXPORT_SYMBOL(lock_can_diag_mutex);
+
+void unlock_can_diag_mutex(struct net *net)
+{
+	mutex_unlock(&net->can.sklist_lock);
+}
+EXPORT_SYMBOL(unlock_can_diag_mutex);
+
+void can_add_sock_sklist(struct sock *sk)
+{
+	struct net *net;
+
+	net = sock_net(sk);
+
+	lock_can_diag_mutex(net);
+	sk_add_node(sk, &net->can.sklist);
+	unlock_can_diag_mutex(net);
+}
+EXPORT_SYMBOL(can_add_sock_sklist);
+
+void can_remove_sock_sklist(struct sock *sk)
+{
+	struct net *net;
+
+	net = sock_net(sk);
+
+	lock_can_diag_mutex(net);
+	sk_del_node_init(sk);
+	unlock_can_diag_mutex(net);
+}
+EXPORT_SYMBOL(can_remove_sock_sklist);
+#endif
+
 static int can_create(struct net *net, struct socket *sock, int protocol,
 		      int kern)
 {
@@ -174,6 +212,8 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
 		sock_put(sk);
 		sock->sk = NULL;
 	} else {
+		can_add_sock_sklist(sk);
+
 		sock_prot_inuse_add(net, sk->sk_prot, 1);
 	}
 
@@ -799,6 +839,12 @@ EXPORT_SYMBOL(can_proto_unregister);
 static int can_pernet_init(struct net *net)
 {
 	spin_lock_init(&net->can.rcvlists_lock);
+
+#if IS_ENABLED(CONFIG_CAN_DIAG)
+	mutex_init(&net->can.sklist_lock);
+	INIT_HLIST_HEAD(&net->can.sklist);
+#endif
+
 	net->can.rx_alldev_list = kzalloc_obj(*net->can.rx_alldev_list);
 	if (!net->can.rx_alldev_list)
 		goto out;
@@ -842,6 +888,10 @@ static void can_pernet_exit(struct net *net)
 	kfree(net->can.rx_alldev_list);
 	kfree(net->can.pkg_stats);
 	kfree(net->can.rcv_lists_stats);
+
+#if IS_ENABLED(CONFIG_CAN_DIAG)
+	WARN_ON_ONCE(!hlist_empty(&net->can.sklist));
+#endif
 }
 
 /* af_can module init/exit functions */
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 3d637a1e0ac1..a90b7aea2869 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1921,6 +1921,8 @@ static int bcm_release(struct socket *sock)
 	if (!sk)
 		return 0;
 
+	can_remove_sock_sklist(sk);
+
 	net = sock_net(sk);
 	bo = bcm_sk(sk);
 
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 155530aedce2..25098c5546d2 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1455,6 +1455,8 @@ static int isotp_release(struct socket *sock)
 	so = isotp_sk(sk);
 	net = sock_net(sk);
 
+	can_remove_sock_sklist(sk);
+
 	/* best-effort: wait for a running pdu to finish, but don't block on
 	 * it forever - give up after the first signal
 	 */
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index ccd43ff5519c..cbfd0b888768 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -641,6 +641,8 @@ static int j1939_sk_release(struct socket *sock)
 	if (!sk)
 		return 0;
 
+	can_remove_sock_sklist(sk);
+
 	lock_sock(sk);
 	jsk = j1939_sk(sk);
 
diff --git a/net/can/raw.c b/net/can/raw.c
index 82d9c0499c95..7784b8fd8d19 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -418,6 +418,8 @@ static int raw_release(struct socket *sock)
 	ro = raw_sk(sk);
 	net = sock_net(sk);
 
+	can_remove_sock_sklist(sk);
+
 	spin_lock(&raw_notifier_lock);
 	while (raw_busy_notifier == ro) {
 		spin_unlock(&raw_notifier_lock);

-- 
2.55.0