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>

1 files changed, 19 insertions, 1 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 7bba469b6828..d563f2ebcbb3 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -206,6 +206,8 @@ static void __l2cap_chan_add(struct l2cap_conn *conn, struct sock *sk, struct so
 
         BT_DBG("conn %p, psm 0x%2.2x, dcid 0x%4.4x", conn, l2cap_pi(sk)->psm, l2cap_pi(sk)->dcid);
 
+        conn->disc_reason = 0x13;
+
         l2cap_pi(sk)->conn = conn;
 
         if (sk->sk_type == SOCK_SEQPACKET) {
@@ -491,6 +493,8 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon, u8 status)
         spin_lock_init(&conn->lock);
         rwlock_init(&conn->chan_list.lock);
 
+        conn->disc_reason = 0x13;
+
         return conn;
 }
 
@@ -1840,6 +1844,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
         /* Check if the ACL is secure enough (if not SDP) */
         if (psm != cpu_to_le16(0x0001) &&
                                 !hci_conn_check_link_mode(conn->hcon)) {
+                conn->disc_reason = 0x05;
                 result = L2CAP_CR_SEC_BLOCK;
                 goto response;
         }
@@ -2472,7 +2477,19 @@ static int l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
         return 0;
 }
 
-static int l2cap_disconn_ind(struct hci_conn *hcon, u8 reason)
+static int l2cap_disconn_ind(struct hci_conn *hcon)
+{
+        struct l2cap_conn *conn = hcon->l2cap_data;
+
+        BT_DBG("hcon %p", hcon);
+
+        if (hcon->type != ACL_LINK || !conn)
+                return 0x13;
+
+        return conn->disc_reason;
+}
+
+static int l2cap_disconn_cfm(struct hci_conn *hcon, u8 reason)
 {
         BT_DBG("hcon %p reason %d", hcon, reason);
 
@@ -2717,6 +2734,7 @@ static struct hci_proto l2cap_hci_proto = {
         .connect_ind    = l2cap_connect_ind,
         .connect_cfm    = l2cap_connect_cfm,
         .disconn_ind    = l2cap_disconn_ind,
+        .disconn_cfm    = l2cap_disconn_cfm,
         .security_cfm   = l2cap_security_cfm,
         .recv_acldata   = l2cap_recv_acldata
 };