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alistair23-linux/net/ieee802154/header_ops.c
Alexander Aring 87a93e4ece ieee802154: change needed headroom/tailroom 
This patch cleanups needed_headroom, needed_tailroom and hard_header_len
fields for wpan and lowpan interfaces.

For wpan interfaces the worst case mac header len should be part of
needed_headroom, currently this is set as hard_header_len, but
hard_header_len should be set to the minimum header length which xmit
call assumes and this is the minimum frame length of 802.15.4.
The hard_header_len value will check inside send callbacl of AF_PACKET
raw sockets.

For lowpan interfaces, if fragmentation isn't needed the skb will
call dev_hard_header for 802154 layer and queue it afterwards. This
happens without new skb allocation, so we need the same headroom and
tailroom lengths like 802154 inside 802154 6lowpan layer. At least we
assume as minimum header length an ipv6 header size.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2015-09-22 11:51:20 +02:00

327 lines
6.8 KiB
C
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/*
* Copyright (C) 2014 Fraunhofer ITWM
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Written by:
* Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
*/
#include <linux/ieee802154.h>
#include <net/mac802154.h>
#include <net/ieee802154_netdev.h>
static int
ieee802154_hdr_push_addr(u8 *buf, const struct ieee802154_addr *addr,
bool omit_pan)
{
int pos = 0;
if (addr->mode == IEEE802154_ADDR_NONE)
return 0;
if (!omit_pan) {
memcpy(buf + pos, &addr->pan_id, 2);
pos += 2;
}
switch (addr->mode) {
case IEEE802154_ADDR_SHORT:
memcpy(buf + pos, &addr->short_addr, 2);
pos += 2;
break;
case IEEE802154_ADDR_LONG:
memcpy(buf + pos, &addr->extended_addr, IEEE802154_ADDR_LEN);
pos += IEEE802154_ADDR_LEN;
break;
default:
return -EINVAL;
}
return pos;
}
static int
ieee802154_hdr_push_sechdr(u8 *buf, const struct ieee802154_sechdr *hdr)
{
int pos = 5;
memcpy(buf, hdr, 1);
memcpy(buf + 1, &hdr->frame_counter, 4);
switch (hdr->key_id_mode) {
case IEEE802154_SCF_KEY_IMPLICIT:
return pos;
case IEEE802154_SCF_KEY_INDEX:
break;
case IEEE802154_SCF_KEY_SHORT_INDEX:
memcpy(buf + pos, &hdr->short_src, 4);
pos += 4;
break;
case IEEE802154_SCF_KEY_HW_INDEX:
memcpy(buf + pos, &hdr->extended_src, IEEE802154_ADDR_LEN);
pos += IEEE802154_ADDR_LEN;
break;
}
buf[pos++] = hdr->key_id;
return pos;
}
int
ieee802154_hdr_push(struct sk_buff *skb, struct ieee802154_hdr *hdr)
{
u8 buf[IEEE802154_MAX_HEADER_LEN];
int pos = 2;
int rc;
struct ieee802154_hdr_fc *fc = &hdr->fc;
buf[pos++] = hdr->seq;
fc->dest_addr_mode = hdr->dest.mode;
rc = ieee802154_hdr_push_addr(buf + pos, &hdr->dest, false);
if (rc < 0)
return -EINVAL;
pos += rc;
fc->source_addr_mode = hdr->source.mode;
if (hdr->source.pan_id == hdr->dest.pan_id &&
hdr->dest.mode != IEEE802154_ADDR_NONE)
fc->intra_pan = true;
rc = ieee802154_hdr_push_addr(buf + pos, &hdr->source, fc->intra_pan);
if (rc < 0)
return -EINVAL;
pos += rc;
if (fc->security_enabled) {
fc->version = 1;
rc = ieee802154_hdr_push_sechdr(buf + pos, &hdr->sec);
if (rc < 0)
return -EINVAL;
pos += rc;
}
memcpy(buf, fc, 2);
memcpy(skb_push(skb, pos), buf, pos);
return pos;
}
EXPORT_SYMBOL_GPL(ieee802154_hdr_push);
static int
ieee802154_hdr_get_addr(const u8 *buf, int mode, bool omit_pan,
struct ieee802154_addr *addr)
{
int pos = 0;
addr->mode = mode;
if (mode == IEEE802154_ADDR_NONE)
return 0;
if (!omit_pan) {
memcpy(&addr->pan_id, buf + pos, 2);
pos += 2;
}
if (mode == IEEE802154_ADDR_SHORT) {
memcpy(&addr->short_addr, buf + pos, 2);
return pos + 2;
} else {
memcpy(&addr->extended_addr, buf + pos, IEEE802154_ADDR_LEN);
return pos + IEEE802154_ADDR_LEN;
}
}
static int ieee802154_hdr_addr_len(int mode, bool omit_pan)
{
int pan_len = omit_pan ? 0 : 2;
switch (mode) {
case IEEE802154_ADDR_NONE: return 0;
case IEEE802154_ADDR_SHORT: return 2 + pan_len;
case IEEE802154_ADDR_LONG: return IEEE802154_ADDR_LEN + pan_len;
default: return -EINVAL;
}
}
static int
ieee802154_hdr_get_sechdr(const u8 *buf, struct ieee802154_sechdr *hdr)
{
int pos = 5;
memcpy(hdr, buf, 1);
memcpy(&hdr->frame_counter, buf + 1, 4);
switch (hdr->key_id_mode) {
case IEEE802154_SCF_KEY_IMPLICIT:
return pos;
case IEEE802154_SCF_KEY_INDEX:
break;
case IEEE802154_SCF_KEY_SHORT_INDEX:
memcpy(&hdr->short_src, buf + pos, 4);
pos += 4;
break;
case IEEE802154_SCF_KEY_HW_INDEX:
memcpy(&hdr->extended_src, buf + pos, IEEE802154_ADDR_LEN);
pos += IEEE802154_ADDR_LEN;
break;
}
hdr->key_id = buf[pos++];
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)
{
return ieee802154_sechdr_lengths[IEEE802154_SCF_KEY_ID_MODE(sc)];
}
static int ieee802154_hdr_minlen(const struct ieee802154_hdr *hdr)
{
int dlen, slen;
dlen = ieee802154_hdr_addr_len(hdr->fc.dest_addr_mode, false);
slen = ieee802154_hdr_addr_len(hdr->fc.source_addr_mode,
hdr->fc.intra_pan);
if (slen < 0 || dlen < 0)
return -EINVAL;
return 3 + dlen + slen + hdr->fc.security_enabled;
}
static int
ieee802154_hdr_get_addrs(const u8 *buf, struct ieee802154_hdr *hdr)
{
int pos = 0;
pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.dest_addr_mode,
false, &hdr->dest);
pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.source_addr_mode,
hdr->fc.intra_pan, &hdr->source);
if (hdr->fc.intra_pan)
hdr->source.pan_id = hdr->dest.pan_id;
return pos;
}
int
ieee802154_hdr_pull(struct sk_buff *skb, struct ieee802154_hdr *hdr)
{
int pos = 3, rc;
if (!pskb_may_pull(skb, 3))
return -EINVAL;
memcpy(hdr, skb->data, 3);
rc = ieee802154_hdr_minlen(hdr);
if (rc < 0 || !pskb_may_pull(skb, rc))
return -EINVAL;
pos += ieee802154_hdr_get_addrs(skb->data + pos, hdr);
if (hdr->fc.security_enabled) {
int want = pos + ieee802154_hdr_sechdr_len(skb->data[pos]);
if (!pskb_may_pull(skb, want))
return -EINVAL;
pos += ieee802154_hdr_get_sechdr(skb->data + pos, &hdr->sec);
}
skb_pull(skb, pos);
return pos;
}
EXPORT_SYMBOL_GPL(ieee802154_hdr_pull);
int
ieee802154_hdr_peek_addrs(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
{
const u8 *buf = skb_mac_header(skb);
int pos = 3, rc;
if (buf + 3 > skb_tail_pointer(skb))
return -EINVAL;
memcpy(hdr, buf, 3);
rc = ieee802154_hdr_minlen(hdr);
if (rc < 0 || buf + rc > skb_tail_pointer(skb))
return -EINVAL;
pos += ieee802154_hdr_get_addrs(buf + pos, 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);
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