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linux/net/mac802154/rx.c
Markus Elfring 56f9ebe641 mac802154: Delete an unnecessary check before the function call "kfree_skb" 
The kfree_skb() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2015-11-19 17:50:32 +01:00

307 lines
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/*
* Copyright (C) 2007-2012 Siemens AG
*
* 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:
* Pavel Smolenskiy <pavel.smolenskiy@gmail.com>
* Maxim Gorbachyov <maxim.gorbachev@siemens.com>
* Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
* Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/crc-ccitt.h>
#include <asm/unaligned.h>
#include <net/mac802154.h>
#include <net/ieee802154_netdev.h>
#include <net/nl802154.h>
#include "ieee802154_i.h"
static int ieee802154_deliver_skb(struct sk_buff *skb)
{
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb->protocol = htons(ETH_P_IEEE802154);
return netif_receive_skb(skb);
}
static int
ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
struct sk_buff *skb, const struct ieee802154_hdr *hdr)
{
struct wpan_dev *wpan_dev = &sdata->wpan_dev;
__le16 span, sshort;
int rc;
pr_debug("getting packet via slave interface %s\n", sdata->dev->name);
span = wpan_dev->pan_id;
sshort = wpan_dev->short_addr;
switch (mac_cb(skb)->dest.mode) {
case IEEE802154_ADDR_NONE:
if (mac_cb(skb)->dest.mode != IEEE802154_ADDR_NONE)
/* FIXME: check if we are PAN coordinator */
skb->pkt_type = PACKET_OTHERHOST;
else
/* ACK comes with both addresses empty */
skb->pkt_type = PACKET_HOST;
break;
case IEEE802154_ADDR_LONG:
if (mac_cb(skb)->dest.pan_id != span &&
mac_cb(skb)->dest.pan_id != cpu_to_le16(IEEE802154_PANID_BROADCAST))
skb->pkt_type = PACKET_OTHERHOST;
else if (mac_cb(skb)->dest.extended_addr == wpan_dev->extended_addr)
skb->pkt_type = PACKET_HOST;
else
skb->pkt_type = PACKET_OTHERHOST;
break;
case IEEE802154_ADDR_SHORT:
if (mac_cb(skb)->dest.pan_id != span &&
mac_cb(skb)->dest.pan_id != cpu_to_le16(IEEE802154_PANID_BROADCAST))
skb->pkt_type = PACKET_OTHERHOST;
else if (mac_cb(skb)->dest.short_addr == sshort)
skb->pkt_type = PACKET_HOST;
else if (mac_cb(skb)->dest.short_addr ==
cpu_to_le16(IEEE802154_ADDR_BROADCAST))
skb->pkt_type = PACKET_BROADCAST;
else
skb->pkt_type = PACKET_OTHERHOST;
break;
default:
pr_debug("invalid dest mode\n");
goto fail;
}
skb->dev = sdata->dev;
/* TODO this should be moved after netif_receive_skb call, otherwise
* wireshark will show a mac header with security fields and the
* payload is already decrypted.
*/
rc = mac802154_llsec_decrypt(&sdata->sec, skb);
if (rc) {
pr_debug("decryption failed: %i\n", rc);
goto fail;
}
sdata->dev->stats.rx_packets++;
sdata->dev->stats.rx_bytes += skb->len;
switch (mac_cb(skb)->type) {
case IEEE802154_FC_TYPE_DATA:
return ieee802154_deliver_skb(skb);
default:
pr_warn("ieee802154: bad frame received (type = %d)\n",
mac_cb(skb)->type);
goto fail;
}
fail:
kfree_skb(skb);
return NET_RX_DROP;
}
static void
ieee802154_print_addr(const char *name, const struct ieee802154_addr *addr)
{
if (addr->mode == IEEE802154_ADDR_NONE)
pr_debug("%s not present\n", name);
pr_debug("%s PAN ID: %04x\n", name, le16_to_cpu(addr->pan_id));
if (addr->mode == IEEE802154_ADDR_SHORT) {
pr_debug("%s is short: %04x\n", name,
le16_to_cpu(addr->short_addr));
} else {
u64 hw = swab64((__force u64)addr->extended_addr);
pr_debug("%s is hardware: %8phC\n", name, &hw);
}
}
static int
ieee802154_parse_frame_start(struct sk_buff *skb, struct ieee802154_hdr *hdr)
{
int hlen;
struct ieee802154_mac_cb *cb = mac_cb_init(skb);
skb_reset_mac_header(skb);
hlen = ieee802154_hdr_pull(skb, hdr);
if (hlen < 0)
return -EINVAL;
skb->mac_len = hlen;
pr_debug("fc: %04x dsn: %02x\n", le16_to_cpup((__le16 *)&hdr->fc),
hdr->seq);
cb->type = hdr->fc.type;
cb->ackreq = hdr->fc.ack_request;
cb->secen = hdr->fc.security_enabled;
ieee802154_print_addr("destination", &hdr->dest);
ieee802154_print_addr("source", &hdr->source);
cb->source = hdr->source;
cb->dest = hdr->dest;
if (hdr->fc.security_enabled) {
u64 key;
pr_debug("seclevel %i\n", hdr->sec.level);
switch (hdr->sec.key_id_mode) {
case IEEE802154_SCF_KEY_IMPLICIT:
pr_debug("implicit key\n");
break;
case IEEE802154_SCF_KEY_INDEX:
pr_debug("key %02x\n", hdr->sec.key_id);
break;
case IEEE802154_SCF_KEY_SHORT_INDEX:
pr_debug("key %04x:%04x %02x\n",
le32_to_cpu(hdr->sec.short_src) >> 16,
le32_to_cpu(hdr->sec.short_src) & 0xffff,
hdr->sec.key_id);
break;
case IEEE802154_SCF_KEY_HW_INDEX:
key = swab64((__force u64)hdr->sec.extended_src);
pr_debug("key source %8phC %02x\n", &key,
hdr->sec.key_id);
break;
}
}
return 0;
}
static void
__ieee802154_rx_handle_packet(struct ieee802154_local *local,
struct sk_buff *skb)
{
int ret;
struct ieee802154_sub_if_data *sdata;
struct ieee802154_hdr hdr;
ret = ieee802154_parse_frame_start(skb, &hdr);
if (ret) {
pr_debug("got invalid frame\n");
kfree_skb(skb);
return;
}
list_for_each_entry_rcu(sdata, &local->interfaces, list) {
if (sdata->wpan_dev.iftype != NL802154_IFTYPE_NODE)
continue;
if (!ieee802154_sdata_running(sdata))
continue;
ieee802154_subif_frame(sdata, skb, &hdr);
skb = NULL;
break;
}
kfree_skb(skb);
}
static void
ieee802154_monitors_rx(struct ieee802154_local *local, struct sk_buff *skb)
{
struct sk_buff *skb2;
struct ieee802154_sub_if_data *sdata;
skb_reset_mac_header(skb);
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb->pkt_type = PACKET_OTHERHOST;
skb->protocol = htons(ETH_P_IEEE802154);
list_for_each_entry_rcu(sdata, &local->interfaces, list) {
if (sdata->wpan_dev.iftype != NL802154_IFTYPE_MONITOR)
continue;
if (!ieee802154_sdata_running(sdata))
continue;
skb2 = skb_clone(skb, GFP_ATOMIC);
if (skb2) {
skb2->dev = sdata->dev;
ieee802154_deliver_skb(skb2);
sdata->dev->stats.rx_packets++;
sdata->dev->stats.rx_bytes += skb->len;
}
}
}
void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb)
{
u16 crc;
WARN_ON_ONCE(softirq_count() == 0);
if (local->suspended)
goto drop;
/* TODO: When a transceiver omits the checksum here, we
* add an own calculated one. This is currently an ugly
* solution because the monitor needs a crc here.
*/
if (local->hw.flags & IEEE802154_HW_RX_OMIT_CKSUM) {
crc = crc_ccitt(0, skb->data, skb->len);
put_unaligned_le16(crc, skb_put(skb, 2));
}
rcu_read_lock();
ieee802154_monitors_rx(local, skb);
/* Check if transceiver doesn't validate the checksum.
* If not we validate the checksum here.
*/
if (local->hw.flags & IEEE802154_HW_RX_DROP_BAD_CKSUM) {
crc = crc_ccitt(0, skb->data, skb->len);
if (crc) {
rcu_read_unlock();
goto drop;
}
}
/* remove crc */
skb_trim(skb, skb->len - 2);
__ieee802154_rx_handle_packet(local, skb);
rcu_read_unlock();
return;
drop:
kfree_skb(skb);
}
void
ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb, u8 lqi)
{
struct ieee802154_local *local = hw_to_local(hw);
mac_cb(skb)->lqi = lqi;
skb->pkt_type = IEEE802154_RX_MSG;
skb_queue_tail(&local->skb_queue, skb);
tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee802154_rx_irqsafe);
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