Bluetooth: Resume BT_CONNECTED state after LE security elevation

The LE ATT socket uses a special trick where it temporarily sets
BT_CONFIG state for the duration of a security level elevation. In order
to not require special hacks for going back to BT_CONNECTED state in the
l2cap_core.c code the most reasonable place to resume the state is the
resume callback. This patch adds a new flag to track the pending
security level change and ensures that the state is set back to
BT_CONNECTED in the resume callback in case the flag is set.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/l2cap.h

@@ -708,6 +708,7 @@ enum {
 	FLAG_EFS_ENABLE,
 	FLAG_DEFER_SETUP,
 	FLAG_LE_CONN_REQ_SENT,
+	FLAG_PENDING_SECURITY,
 };
 
 enum {

net/bluetooth/l2cap_sock.c

@@ -790,6 +790,7 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 		if (chan->scid == L2CAP_CID_ATT) {
 			if (smp_conn_security(conn->hcon, sec.level))
 				break;
+			set_bit(FLAG_PENDING_SECURITY, &chan->flags);
 			sk->sk_state = BT_CONFIG;
 			chan->state = BT_CONFIG;
 
@@ -1359,6 +1360,11 @@ static void l2cap_sock_resume_cb(struct l2cap_chan *chan)
 {
 	struct sock *sk = chan->data;
 
+	if (test_and_clear_bit(FLAG_PENDING_SECURITY, &chan->flags)) {
+		sk->sk_state = BT_CONNECTED;
+		chan->state = BT_CONNECTED;
+	}
+
 	clear_bit(BT_SK_SUSPEND, &bt_sk(sk)->flags);
 	sk->sk_state_change(sk);
 }