Bluetooth: Add new BT_SNDMTU and BT_RCVMTU socket options

This patch adds new socket options for LE sockets since the existing
L2CAP_OPTIONS socket option is not usable for LE. For now, the new
socket options also require LE CoC support to be explicitly enabled to
leave some playroom in case something needs to be changed in a backwards
incompatible way.

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

include/net/bluetooth/bluetooth.h

@@ -115,6 +115,9 @@ struct bt_voice {
 #define BT_VOICE_TRANSPARENT			0x0003
 #define BT_VOICE_CVSD_16BIT			0x0060
 
+#define BT_SNDMTU		12
+#define BT_RCVMTU		13
+
 __printf(1, 2)
 int bt_info(const char *fmt, ...);
 __printf(1, 2)

net/bluetooth/l2cap_sock.c

@@ -534,6 +534,41 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname,
 			err = -EFAULT;
 		break;
 
+	case BT_SNDMTU:
+		if (!enable_lecoc) {
+			err = -EPROTONOSUPPORT;
+			break;
+		}
+
+		if (!bdaddr_type_is_le(chan->src_type)) {
+			err = -EINVAL;
+			break;
+		}
+
+		if (sk->sk_state != BT_CONNECTED) {
+			err = -ENOTCONN;
+			break;
+		}
+
+		if (put_user(chan->omtu, (u16 __user *) optval))
+			err = -EFAULT;
+		break;
+
+	case BT_RCVMTU:
+		if (!enable_lecoc) {
+			err = -EPROTONOSUPPORT;
+			break;
+		}
+
+		if (!bdaddr_type_is_le(chan->src_type)) {
+			err = -EINVAL;
+			break;
+		}
+
+		if (put_user(chan->imtu, (u16 __user *) optval))
+			err = -EFAULT;
+		break;
+
 	default:
 		err = -ENOPROTOOPT;
 		break;
@@ -834,6 +869,47 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case BT_SNDMTU:
+		if (!enable_lecoc) {
+			err = -EPROTONOSUPPORT;
+			break;
+		}
+
+		if (!bdaddr_type_is_le(chan->src_type)) {
+			err = -EINVAL;
+			break;
+		}
+
+		/* Setting is not supported as it's the remote side that
+		 * decides this.
+		 */
+		err = -EPERM;
+		break;
+
+	case BT_RCVMTU:
+		if (!enable_lecoc) {
+			err = -EPROTONOSUPPORT;
+			break;
+		}
+
+		if (!bdaddr_type_is_le(chan->src_type)) {
+			err = -EINVAL;
+			break;
+		}
+
+		if (sk->sk_state == BT_CONNECTED) {
+			err = -EISCONN;
+			break;
+		}
+
+		if (get_user(opt, (u32 __user *) optval)) {
+			err = -EFAULT;
+			break;
+		}
+
+		chan->imtu = opt;
+		break;
+
 	default:
 		err = -ENOPROTOOPT;
 		break;