Bluetooth: Allow 3D profile to use security mode 4 level 0

The PSM 0x0021 is dedicated to the 3D profile and has permission to
use security mode 4 level 0 for L2CAP connectionless unicast data
transfers.

When establishing a L2CAP connectionless channel on PSM 0x0021, it
will no longer force Secure Simple Pairing.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/l2cap.h

@@ -237,6 +237,7 @@ struct l2cap_conn_rsp {
 /* protocol/service multiplexer (PSM) */
 #define L2CAP_PSM_SDP		0x0001
 #define L2CAP_PSM_RFCOMM	0x0003
+#define L2CAP_PSM_3DSP		0x0021
 
 /* channel indentifier */
 #define L2CAP_CID_SIGNALING	0x0001

net/bluetooth/l2cap_core.c

@@ -688,6 +688,16 @@ static inline u8 l2cap_get_auth_type(struct l2cap_chan *chan)
 			return HCI_AT_NO_BONDING;
 		}
 		break;
+	case L2CAP_CHAN_CONN_LESS:
+		if (chan->psm == __constant_cpu_to_le16(L2CAP_PSM_3DSP)) {
+			if (chan->sec_level == BT_SECURITY_LOW)
+				chan->sec_level = BT_SECURITY_SDP;
+		}
+		if (chan->sec_level == BT_SECURITY_HIGH)
+			return HCI_AT_NO_BONDING_MITM;
+		else
+			return HCI_AT_NO_BONDING;
+		break;
 	case L2CAP_CHAN_CONN_ORIENTED:
 		if (chan->psm == __constant_cpu_to_le16(L2CAP_PSM_SDP)) {
 			if (chan->sec_level == BT_SECURITY_LOW)

net/bluetooth/l2cap_sock.c

@@ -101,6 +101,10 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 		goto done;
 
 	switch (chan->chan_type) {
+	case L2CAP_CHAN_CONN_LESS:
+		if (__le16_to_cpu(la.l2_psm) == L2CAP_PSM_3DSP)
+			chan->sec_level = BT_SECURITY_SDP;
+		break;
 	case L2CAP_CHAN_CONN_ORIENTED:
 		if (__le16_to_cpu(la.l2_psm) == L2CAP_PSM_SDP ||
 		    __le16_to_cpu(la.l2_psm) == L2CAP_PSM_RFCOMM)