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@xxxxxxxxxxxxxxx>
Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx>
---
include/linux/ieee802154.h | 25 +++++++++++++++++++++++++
include/net/mac802154.h | 15 +++++++++++++++
net/ieee802154/6lowpan/rx.c | 8 ++++++++
3 files changed, 48 insertions(+)
diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
index 1dc1f4e..db01492 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 b7f9961..32bd7c0 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
diff --git a/net/ieee802154/6lowpan/rx.c b/net/ieee802154/6lowpan/rx.c
index 45ce121..f7eb091 100644
--- a/net/ieee802154/6lowpan/rx.c
+++ b/net/ieee802154/6lowpan/rx.c
@@ -11,6 +11,7 @@
#include <linux/if_arp.h>
#include <net/6lowpan.h>
+#include <net/mac802154.h>
#include <net/ieee802154_netdev.h>
#include "6lowpan_i.h"
@@ -280,6 +281,13 @@ static inline bool lowpan_is_reserved(u8 dispatch)
*/
static inline bool lowpan_rx_h_check(struct sk_buff *skb)
{
+ __le16 fc = ieee802154_get_fc_from_skb(skb);
+
+ /* check on ieee802154 conform 6LoWPAN header */
+ if (!ieee802154_is_data(fc) ||
+ !ieee802154_is_intra_pan(fc))
+ return false;
+
/* check if we can dereference the dispatch */
if (unlikely(!skb->len))
return false;
--
2.5.1
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