ieee802154: 6lowpan: check on valid 802.15.4 frame

This patch adds frame control checks to check if the received frame is
something which could contain a 6LoWPAN packet.

Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

2 files changed, 40 insertions, 0 deletions

diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
index 1dc1f4ed4001..db01492814d3 100644
--- a/include/linux/ieee802154.h
+++ b/include/linux/ieee802154.h
@@ -205,6 +205,31 @@ enum {
 	IEEE802154_SCAN_IN_PROGRESS = 0xfc,
 };
 
+/* frame control handling */
+#define IEEE802154_FCTL_FTYPE		0x0003
+#define IEEE802154_FCTL_INTRA_PAN	0x0040
+
+#define IEEE802154_FTYPE_DATA		0x0001
+
+/*
+ * ieee802154_is_data - check if type is IEEE802154_FTYPE_DATA
+ * @fc: frame control bytes in little-endian byteorder
+ */
+static inline int ieee802154_is_data(__le16 fc)
+{
+	return (fc & cpu_to_le16(IEEE802154_FCTL_FTYPE)) ==
+		cpu_to_le16(IEEE802154_FTYPE_DATA);
+}
+
+/**
+ * ieee802154_is_intra_pan - check if intra pan id communication
+ * @fc: frame control bytes in little-endian byteorder
+ */
+static inline bool ieee802154_is_intra_pan(__le16 fc)
+{
+	return fc & cpu_to_le16(IEEE802154_FCTL_INTRA_PAN);
+}
+
 /**
  * ieee802154_is_valid_psdu_len - check if psdu len is valid
  * available lengths:
diff --git a/include/net/mac802154.h b/include/net/mac802154.h
index b7f99615224b..32bd7c0467d4 100644
--- a/include/net/mac802154.h
+++ b/include/net/mac802154.h
@@ -250,6 +250,21 @@ struct ieee802154_ops {
 };
 
 /**
+ * ieee802154_get_fc_from_skb - get the frame control field from an skb
+ * @skb: skb where the frame control field will be get from
+ */
+static inline __le16 ieee802154_get_fc_from_skb(const struct sk_buff *skb)
+{
+	/* return some invalid fc on failure */
+	if (unlikely(skb->mac_len < 2)) {
+		WARN_ON(1);
+		return cpu_to_le16(0);
+	}
+
+	return (__force __le16)__get_unaligned_memmove16(skb_mac_header(skb));
+}
+
+/**
  * ieee802154_be64_to_le64 - copies and convert be64 to le64
  * @le64_dst: le64 destination pointer
  * @be64_src: be64 source pointer