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Message-Id: <1400001846-5349-2-git-send-email-phoebe.buckheister@itwm.fraunhofer.de>
Date: Tue, 13 May 2014 19:24:02 +0200
From: Phoebe Buckheister <phoebe.buckheister@...m.fraunhofer.de>
To: netdev@...r.kernel.org
Cc: linux-zigbee-devel@...ts.sourceforge.net, davem@...emloft.net,
Phoebe Buckheister <phoebe.buckheister@...m.fraunhofer.de>
Subject: [PATCH net-next 1/5] ieee802154: add definitions for link-layer security and header functions
When dealing with 802.15.4, one often has to know the maximum payload
size for a given packet. This depends on many factors, one of which is
whether or not a security header is present in the frame. These
definitions and functions provide an easy way for any upper layer to
calculate the maximum payload size for a packet. The first obvious user
for this is 6lowpan, which duplicates this calculation and gets it
partially wrong because it ignores security headers.
Signed-off-by: Phoebe Buckheister <phoebe.buckheister@...m.fraunhofer.de>
---
include/net/ieee802154.h | 9 +++++++
include/net/ieee802154_netdev.h | 29 ++++++++++++++++++++++
net/ieee802154/header_ops.c | 52 +++++++++++++++++++++++++++++++++------
3 files changed, 83 insertions(+), 7 deletions(-)
diff --git a/include/net/ieee802154.h b/include/net/ieee802154.h
index c7ae0ac..0aa7122 100644
--- a/include/net/ieee802154.h
+++ b/include/net/ieee802154.h
@@ -79,6 +79,15 @@
#define IEEE802154_SCF_KEY_SHORT_INDEX 2
#define IEEE802154_SCF_KEY_HW_INDEX 3
+#define IEEE802154_SCF_SECLEVEL_NONE 0
+#define IEEE802154_SCF_SECLEVEL_MIC32 1
+#define IEEE802154_SCF_SECLEVEL_MIC64 2
+#define IEEE802154_SCF_SECLEVEL_MIC128 3
+#define IEEE802154_SCF_SECLEVEL_ENC 4
+#define IEEE802154_SCF_SECLEVEL_ENC_MIC32 5
+#define IEEE802154_SCF_SECLEVEL_ENC_MIC64 6
+#define IEEE802154_SCF_SECLEVEL_ENC_MIC128 7
+
/* 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 5a719ca..6e4d3e1 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -27,6 +27,7 @@
#ifndef IEEE802154_NETDEVICE_H
#define IEEE802154_NETDEVICE_H
+#include <net/ieee802154.h>
#include <net/af_ieee802154.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
@@ -114,6 +115,34 @@ int ieee802154_hdr_pull(struct sk_buff *skb, struct ieee802154_hdr *hdr);
int ieee802154_hdr_peek_addrs(const struct sk_buff *skb,
struct ieee802154_hdr *hdr);
+/* parses the full 802.15.4 header 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(const struct sk_buff *skb, struct ieee802154_hdr *hdr);
+
+int ieee802154_max_payload(const struct ieee802154_hdr *hdr);
+
+static inline int
+ieee802154_sechdr_authtag_len(const struct ieee802154_sechdr *sec)
+{
+ switch (sec->level) {
+ case IEEE802154_SCF_SECLEVEL_MIC32:
+ case IEEE802154_SCF_SECLEVEL_ENC_MIC32:
+ return 4;
+ case IEEE802154_SCF_SECLEVEL_MIC64:
+ case IEEE802154_SCF_SECLEVEL_ENC_MIC64:
+ return 8;
+ case IEEE802154_SCF_SECLEVEL_MIC128:
+ case IEEE802154_SCF_SECLEVEL_ENC_MIC128:
+ return 16;
+ case IEEE802154_SCF_SECLEVEL_NONE:
+ case IEEE802154_SCF_SECLEVEL_ENC:
+ default:
+ return 0;
+ }
+}
+
static inline int ieee802154_hdr_length(struct sk_buff *skb)
{
struct ieee802154_hdr hdr;
diff --git a/net/ieee802154/header_ops.c b/net/ieee802154/header_ops.c
index bed42a4..c09294e 100644
--- a/net/ieee802154/header_ops.c
+++ b/net/ieee802154/header_ops.c
@@ -195,15 +195,16 @@ ieee802154_hdr_get_sechdr(const u8 *buf, struct ieee802154_sechdr *hdr)
return pos;
}
+static int ieee802154_sechdr_lengths[4] = {
+ [IEEE802154_SCF_KEY_IMPLICIT] = 5,
+ [IEEE802154_SCF_KEY_INDEX] = 6,
+ [IEEE802154_SCF_KEY_SHORT_INDEX] = 10,
+ [IEEE802154_SCF_KEY_HW_INDEX] = 14,
+};
+
static int ieee802154_hdr_sechdr_len(u8 sc)
{
- switch (IEEE802154_SCF_KEY_ID_MODE(sc)) {
- case IEEE802154_SCF_KEY_IMPLICIT: return 5;
- case IEEE802154_SCF_KEY_INDEX: return 6;
- case IEEE802154_SCF_KEY_SHORT_INDEX: return 10;
- case IEEE802154_SCF_KEY_HW_INDEX: return 14;
- default: return -EINVAL;
- }
+ return ieee802154_sechdr_lengths[IEEE802154_SCF_KEY_ID_MODE(sc)];
}
static int ieee802154_hdr_minlen(const struct ieee802154_hdr *hdr)
@@ -285,3 +286,40 @@ ieee802154_hdr_peek_addrs(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
return pos;
}
EXPORT_SYMBOL_GPL(ieee802154_hdr_peek_addrs);
+
+int
+ieee802154_hdr_peek(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
+{
+ const u8 *buf = skb_mac_header(skb);
+ int pos;
+
+ pos = ieee802154_hdr_peek_addrs(skb, hdr);
+ if (pos < 0)
+ return -EINVAL;
+
+ if (hdr->fc.security_enabled) {
+ u8 key_id_mode = IEEE802154_SCF_KEY_ID_MODE(*(buf + pos));
+ int want = pos + ieee802154_sechdr_lengths[key_id_mode];
+
+ if (buf + want > skb_tail_pointer(skb))
+ return -EINVAL;
+
+ pos += ieee802154_hdr_get_sechdr(buf + pos, &hdr->sec);
+ }
+
+ return pos;
+}
+EXPORT_SYMBOL_GPL(ieee802154_hdr_peek);
+
+int ieee802154_max_payload(const struct ieee802154_hdr *hdr)
+{
+ int hlen = ieee802154_hdr_minlen(hdr);
+
+ if (hdr->fc.security_enabled) {
+ hlen += ieee802154_sechdr_lengths[hdr->sec.key_id_mode] - 1;
+ hlen += ieee802154_sechdr_authtag_len(&hdr->sec);
+ }
+
+ return IEEE802154_MTU - hlen - IEEE802154_MFR_SIZE;
+}
+EXPORT_SYMBOL_GPL(ieee802154_max_payload);
--
1.7.9.5
--
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