Bluetooth: Ask upper layers for HCI disconnect reason

Some of the qualification tests demand that in case of failures in L2CAP
the HCI disconnect should indicate a reason why L2CAP fails. This is a
bluntly layer violation since multiple L2CAP connections could be using
the same ACL and thus forcing a disconnect reason is not a good idea.

To comply with the Bluetooth test specification, the disconnect reason
is now stored in the L2CAP connection structure and every time a new
L2CAP channel is added it will set back to its default. So only in the
case where the L2CAP channel with the disconnect reason is really the
last one, it will propagated to the HCI layer.

The HCI layer has been extended with a disconnect indication that allows
it to ask upper layers for a disconnect reason. The upper layer must not
support this callback and in that case it will nicely default to the
existing behavior. If an upper layer like L2CAP can provide a disconnect
reason that one will be used to disconnect the ACL or SCO link.

No modification to the ACL disconnect timeout have been made. So in case
of Linux to Linux connection the initiator will disconnect the ACL link
before the acceptor side can signal the specific disconnect reason. That
is perfectly fine since Linux doesn't make use of this value anyway. The
L2CAP layer has a perfect valid error code for rejecting connection due
to a security violation. It is unclear why the Bluetooth specification
insists on having specific HCI disconnect reason.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

2 files changed, 23 insertions, 4 deletions

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 9473fce499e7..01f9316b4c23 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -478,7 +478,8 @@ struct hci_proto {
 
         int (*connect_ind)      (struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 type);
         int (*connect_cfm)      (struct hci_conn *conn, __u8 status);
-        int (*disconn_ind)      (struct hci_conn *conn, __u8 reason);
+        int (*disconn_ind)      (struct hci_conn *conn);
+        int (*disconn_cfm)      (struct hci_conn *conn, __u8 reason);
         int (*recv_acldata)     (struct hci_conn *conn, struct sk_buff *skb, __u16 flags);
         int (*recv_scodata)     (struct hci_conn *conn, struct sk_buff *skb);
         int (*security_cfm)     (struct hci_conn *conn, __u8 status, __u8 encrypt);
@@ -513,17 +514,33 @@ static inline void hci_proto_connect_cfm(struct hci_conn *conn, __u8 status)
                 hp->connect_cfm(conn, status);
 }
 
-static inline void hci_proto_disconn_ind(struct hci_conn *conn, __u8 reason)
+static inline int hci_proto_disconn_ind(struct hci_conn *conn)
 {
         register struct hci_proto *hp;
+        int reason = 0x13;
 
         hp = hci_proto[HCI_PROTO_L2CAP];
         if (hp && hp->disconn_ind)
-                hp->disconn_ind(conn, reason);
+                reason = hp->disconn_ind(conn);
 
         hp = hci_proto[HCI_PROTO_SCO];
         if (hp && hp->disconn_ind)
-                hp->disconn_ind(conn, reason);
+                reason = hp->disconn_ind(conn);
+
+        return reason;
+}
+
+static inline void hci_proto_disconn_cfm(struct hci_conn *conn, __u8 reason)
+{
+        register struct hci_proto *hp;
+
+        hp = hci_proto[HCI_PROTO_L2CAP];
+        if (hp && hp->disconn_cfm)
+                hp->disconn_cfm(conn, reason);
+
+        hp = hci_proto[HCI_PROTO_SCO];
+        if (hp && hp->disconn_cfm)
+                hp->disconn_cfm(conn, reason);
 }
 
 static inline void hci_proto_auth_cfm(struct hci_conn *conn, __u8 status)
diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 54737c5dc86c..f566aa1f0a4c 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -221,6 +221,8 @@ struct l2cap_conn {
         __u8            rx_ident;
         __u8            tx_ident;
 
+        __u8            disc_reason;
+
         struct l2cap_chan_list chan_list;
 };