ieee802154: add header structs with endiannes and operations

This patch provides a set of structures to represent 802.15.4 MAC
headers, and a set of operations to push/pull/peek these structs from
skbs. We cannot simply pointer-cast the skb MAC header pointer to these
structs, because 802.15.4 headers are wildly variable - depending on the
first three bytes, virtually all other fields of the header may be
present or not, and be present with different lengths.

The new header creation/parsing routines also support 802.15.4 security
headers, which are currently not supported by the mac802154
implementation of the protocol.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 112 insertions, 4 deletions

diff --git a/include/net/ieee802154.h b/include/net/ieee802154.h
index ee59f8b188dd..c7ae0ac528dc 100644
--- a/include/net/ieee802154.h
+++ b/include/net/ieee802154.h
@@ -42,22 +42,42 @@
             (((x) << IEEE802154_FC_TYPE_SHIFT) & IEEE802154_FC_TYPE_MASK)); \
         } while (0)
 
-#define IEEE802154_FC_SECEN             (1 << 3)
-#define IEEE802154_FC_FRPEND            (1 << 4)
-#define IEEE802154_FC_ACK_REQ           (1 << 5)
-#define IEEE802154_FC_INTRA_PAN         (1 << 6)
+#define IEEE802154_FC_SECEN_SHIFT       3
+#define IEEE802154_FC_SECEN             (1 << IEEE802154_FC_SECEN_SHIFT)
+#define IEEE802154_FC_FRPEND_SHIFT      4
+#define IEEE802154_FC_FRPEND            (1 << IEEE802154_FC_FRPEND_SHIFT)
+#define IEEE802154_FC_ACK_REQ_SHIFT     5
+#define IEEE802154_FC_ACK_REQ           (1 << IEEE802154_FC_ACK_REQ_SHIFT)
+#define IEEE802154_FC_INTRA_PAN_SHIFT   6
+#define IEEE802154_FC_INTRA_PAN         (1 << IEEE802154_FC_INTRA_PAN_SHIFT)
 
 #define IEEE802154_FC_SAMODE_SHIFT      14
 #define IEEE802154_FC_SAMODE_MASK       (3 << IEEE802154_FC_SAMODE_SHIFT)
 #define IEEE802154_FC_DAMODE_SHIFT      10
 #define IEEE802154_FC_DAMODE_MASK       (3 << IEEE802154_FC_DAMODE_SHIFT)
 
+#define IEEE802154_FC_VERSION_SHIFT     12
+#define IEEE802154_FC_VERSION_MASK      (3 << IEEE802154_FC_VERSION_SHIFT)
+#define IEEE802154_FC_VERSION(x)        ((x & IEEE802154_FC_VERSION_MASK) >> IEEE802154_FC_VERSION_SHIFT)
+
 #define IEEE802154_FC_SAMODE(x)         \
         (((x) & IEEE802154_FC_SAMODE_MASK) >> IEEE802154_FC_SAMODE_SHIFT)
 
 #define IEEE802154_FC_DAMODE(x)         \
         (((x) & IEEE802154_FC_DAMODE_MASK) >> IEEE802154_FC_DAMODE_SHIFT)
 
+#define IEEE802154_SCF_SECLEVEL_MASK            7
+#define IEEE802154_SCF_SECLEVEL_SHIFT           0
+#define IEEE802154_SCF_SECLEVEL(x)              (x & IEEE802154_SCF_SECLEVEL_MASK)
+#define IEEE802154_SCF_KEY_ID_MODE_SHIFT        3
+#define IEEE802154_SCF_KEY_ID_MODE_MASK         (3 << IEEE802154_SCF_KEY_ID_MODE_SHIFT)
+#define IEEE802154_SCF_KEY_ID_MODE(x)           \
+        ((x & IEEE802154_SCF_KEY_ID_MODE_MASK) >> IEEE802154_SCF_KEY_ID_MODE_SHIFT)
+
+#define IEEE802154_SCF_KEY_IMPLICIT             0
+#define IEEE802154_SCF_KEY_INDEX                1
+#define IEEE802154_SCF_KEY_SHORT_INDEX          2
+#define IEEE802154_SCF_KEY_HW_INDEX             3
 
 /* MAC footer size */
 #define IEEE802154_MFR_SIZE     2 /* 2 octets */
diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
index e4810d566b1b..c3fc33a78920 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -28,6 +28,28 @@
 #define IEEE802154_NETDEVICE_H
 
 #include <net/af_ieee802154.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+
+struct ieee802154_sechdr {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+        u8 level:3,
+           key_id_mode:2,
+           reserved:3;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+        u8 reserved:3,
+           key_id_mode:2,
+           level:3;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+        u8 key_id;
+        __le32 frame_counter;
+        union {
+                __le32 short_src;
+                __le64 extended_src;
+        };
+};
 
 struct ieee802154_addr {
         u8 mode;
@@ -38,6 +60,71 @@ struct ieee802154_addr {
         };
 };
 
+struct ieee802154_hdr_fc {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+        u16 type:3,
+            security_enabled:1,
+            frame_pending:1,
+            ack_request:1,
+            intra_pan:1,
+            reserved:3,
+            dest_addr_mode:2,
+            version:2,
+            source_addr_mode:2;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+        u16 reserved:1,
+            intra_pan:1,
+            ack_request:1,
+            frame_pending:1,
+            security_enabled:1,
+            type:3,
+            source_addr_mode:2,
+            version:2,
+            dest_addr_mode:2,
+            reserved2:2;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+};
+
+struct ieee802154_hdr {
+        struct ieee802154_hdr_fc fc;
+        u8 seq;
+        struct ieee802154_addr source;
+        struct ieee802154_addr dest;
+        struct ieee802154_sechdr sec;
+};
+
+/* pushes hdr onto the skb. fields of hdr->fc that can be calculated from
+ * the contents of hdr will be, and the actual value of those bits in
+ * hdr->fc will be ignored. this includes the INTRA_PAN bit and the frame
+ * version, if SECEN is set.
+ */
+int ieee802154_hdr_push(struct sk_buff *skb, const struct ieee802154_hdr *hdr);
+
+/* pulls the entire 802.15.4 header off of the skb, including the security
+ * header, and performs pan id decompression
+ */
+int ieee802154_hdr_pull(struct sk_buff *skb, struct ieee802154_hdr *hdr);
+
+/* parses the frame control, sequence number of address fields in a given skb
+ * and stores them into hdr, performing pan id decompression and length checks
+ * to be suitable for use in header_ops.parse
+ */
+int ieee802154_hdr_peek_addrs(const struct sk_buff *skb,
+                              struct ieee802154_hdr *hdr);
+
+static inline int ieee802154_hdr_length(struct sk_buff *skb)
+{
+        struct ieee802154_hdr hdr;
+        int len = ieee802154_hdr_pull(skb, &hdr);
+
+        if (len > 0)
+                skb_push(skb, len);
+
+        return len;
+}
+
 static inline bool ieee802154_addr_equal(const struct ieee802154_addr *a1,
                                          const struct ieee802154_addr *a2)
 {
diff --git a/include/net/mac802154.h b/include/net/mac802154.h
index f74b2a8bf2b6..a591053cae63 100644
--- a/include/net/mac802154.h
+++ b/include/net/mac802154.h
@@ -20,6 +20,7 @@
 #define NET_MAC802154_H
 
 #include <net/af_ieee802154.h>
+#include <linux/skbuff.h>
 
 /* General MAC frame format:
  *  2 bytes: Frame Control