Bluetooth: Fix ATT socket backwards compatibility with user space

Old user space versions bind the Attribute Protocol socket to
BDADDR_BREDR when they should be using BDADDR_LE_PUBLIC or
BDADDR_LE_RANDOM. The kernel recently introduced stricter checks on the
socket parameters but we need to punch this hole for old user space
versions to keep them working.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 34e5a58ffca87df4df67d57b8f3df77ed69c92ce..1f326d9d9132e22d7ca34bf6d5b6114db32599e2 100644 (file)
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -159,8 +159,31 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr,
        if (!bdaddr_type_is_valid(la.l2_bdaddr_type))
                return -EINVAL;
 
-       if (chan->src_type == BDADDR_BREDR && la.l2_bdaddr_type != BDADDR_BREDR)
-               return -EINVAL;
+       /* Check that the socket wasn't bound to something that
+        * conflicts with the address given to connect(). If chan->src
+        * is BDADDR_ANY it means bind() was never used, in which case
+        * chan->src_type and la.l2_bdaddr_type do not need to match.
+        */
+       if (chan->src_type == BDADDR_BREDR && bacmp(&chan->src, BDADDR_ANY) &&
+           bdaddr_type_is_le(la.l2_bdaddr_type)) {
+               /* Old user space versions will try to incorrectly bind
+                * the ATT socket using BDADDR_BREDR. We need to accept
+                * this and fix up the source address type only when
+                * both the source CID and destination CID indicate
+                * ATT. Anything else is an invalid combination.
+                */
+               if (chan->scid != L2CAP_CID_ATT ||
+                   la.l2_cid != __constant_cpu_to_le16(L2CAP_CID_ATT))
+                       return -EINVAL;
+
+               /* We don't have the hdev available here to make a
+                * better decision on random vs public, but since all
+                * user space versions that exhibit this issue anyway do
+                * not support random local addresses assuming public
+                * here is good enough.
+                */
+               chan->src_type = BDADDR_LE_PUBLIC;
+       }
 
        if (chan->src_type != BDADDR_BREDR && la.l2_bdaddr_type == BDADDR_BREDR)
                return -EINVAL;