Bluetooth: notify userspace of security level change

It fixes L2CAP socket based security level elevation during a
connection. The HID profile needs this (for keyboards) and it is the only
way to achieve the security level elevation when using the management
interface to talk to the kernel (hence the management enabling patch
being the one that exposes this issue).

It enables the userspace a security level change when the socket is
already connected and create a way to notify the socket the result of the
request. At the moment of the request the socket is made non writable, if
the request fails the connections closes, otherwise the socket is made
writable again, POLL_OUT is emmited.

Signed-off-by: Gustavo Padovan <gustavo@padovan.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index 262ebd1..a65910b 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -191,6 +191,7 @@
 	struct list_head accept_q;
 	struct sock *parent;
 	u32 defer_setup;
+	bool suspended;
 };
 
 struct bt_sock_list {
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 72eb187..6fb68a9 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -450,7 +450,7 @@
 			sk->sk_state == BT_CONFIG)
 		return mask;
 
-	if (sock_writeable(sk))
+	if (!bt_sk(sk)->suspended && sock_writeable(sk))
 		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
 	else
 		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 6c06525..53680fe 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -2039,6 +2039,12 @@
 
 		clear_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags);
 
+		if (ev->status && conn->state == BT_CONNECTED) {
+			hci_acl_disconn(conn, 0x13);
+			hci_conn_put(conn);
+			goto unlock;
+		}
+
 		if (conn->state == BT_CONFIG) {
 			if (!ev->status)
 				conn->state = BT_CONNECTED;
@@ -2049,6 +2055,7 @@
 			hci_encrypt_cfm(conn, ev->status, ev->encrypt);
 	}
 
+unlock:
 	hci_dev_unlock(hdev);
 }
 
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 94552b3..6f9c25b 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4589,6 +4589,11 @@
 
 		if (!status && (chan->state == BT_CONNECTED ||
 						chan->state == BT_CONFIG)) {
+			struct sock *sk = chan->sk;
+
+			bt_sk(sk)->suspended = false;
+			sk->sk_state_change(sk);
+
 			l2cap_check_encryption(chan, encrypt);
 			l2cap_chan_unlock(chan);
 			continue;
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 29122ed..04e7c17 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -592,10 +592,14 @@
 			sk->sk_state = BT_CONFIG;
 			chan->state = BT_CONFIG;
 
-		/* or for ACL link, under defer_setup time */
-		} else if (sk->sk_state == BT_CONNECT2 &&
-					bt_sk(sk)->defer_setup) {
-			err = l2cap_chan_check_security(chan);
+		/* or for ACL link */
+		} else if ((sk->sk_state == BT_CONNECT2 &&
+			   bt_sk(sk)->defer_setup) ||
+			   sk->sk_state == BT_CONNECTED) {
+			if (!l2cap_chan_check_security(chan))
+				bt_sk(sk)->suspended = true;
+			else
+				sk->sk_state_change(sk);
 		} else {
 			err = -EINVAL;
 		}