linux-stable/include/net/6lowpan.h
Gustavo A. R. Silva 8788a1ee07 6lowpan: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2020-02-28 14:51:30 +01:00

330 lines
10 KiB
C

/*
* Copyright 2011, Siemens AG
* written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
*/
/*
* Based on patches from Jon Smirl <jonsmirl@gmail.com>
* Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* Jon's code is based on 6lowpan implementation for Contiki which is:
* Copyright (c) 2008, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef __6LOWPAN_H__
#define __6LOWPAN_H__
#include <linux/debugfs.h>
#include <net/ipv6.h>
#include <net/net_namespace.h>
/* special link-layer handling */
#include <net/mac802154.h>
#define EUI64_ADDR_LEN 8
#define LOWPAN_NHC_MAX_ID_LEN 1
/* Maximum next header compression length which we currently support inclusive
* possible inline data.
*/
#define LOWPAN_NHC_MAX_HDR_LEN (sizeof(struct udphdr))
/* Max IPHC Header len without IPv6 hdr specific inline data.
* Useful for getting the "extra" bytes we need at worst case compression.
*
* LOWPAN_IPHC + CID + LOWPAN_NHC_MAX_ID_LEN
*/
#define LOWPAN_IPHC_MAX_HEADER_LEN (2 + 1 + LOWPAN_NHC_MAX_ID_LEN)
/* Maximum worst case IPHC header buffer size */
#define LOWPAN_IPHC_MAX_HC_BUF_LEN (sizeof(struct ipv6hdr) + \
LOWPAN_IPHC_MAX_HEADER_LEN + \
LOWPAN_NHC_MAX_HDR_LEN)
/* SCI/DCI is 4 bit width, so we have maximum 16 entries */
#define LOWPAN_IPHC_CTX_TABLE_SIZE (1 << 4)
#define LOWPAN_DISPATCH_IPV6 0x41 /* 01000001 = 65 */
#define LOWPAN_DISPATCH_IPHC 0x60 /* 011xxxxx = ... */
#define LOWPAN_DISPATCH_IPHC_MASK 0xe0
static inline bool lowpan_is_ipv6(u8 dispatch)
{
return dispatch == LOWPAN_DISPATCH_IPV6;
}
static inline bool lowpan_is_iphc(u8 dispatch)
{
return (dispatch & LOWPAN_DISPATCH_IPHC_MASK) == LOWPAN_DISPATCH_IPHC;
}
#define LOWPAN_PRIV_SIZE(llpriv_size) \
(sizeof(struct lowpan_dev) + llpriv_size)
enum lowpan_lltypes {
LOWPAN_LLTYPE_BTLE,
LOWPAN_LLTYPE_IEEE802154,
};
enum lowpan_iphc_ctx_flags {
LOWPAN_IPHC_CTX_FLAG_ACTIVE,
LOWPAN_IPHC_CTX_FLAG_COMPRESSION,
};
struct lowpan_iphc_ctx {
u8 id;
struct in6_addr pfx;
u8 plen;
unsigned long flags;
};
struct lowpan_iphc_ctx_table {
spinlock_t lock;
const struct lowpan_iphc_ctx_ops *ops;
struct lowpan_iphc_ctx table[LOWPAN_IPHC_CTX_TABLE_SIZE];
};
static inline bool lowpan_iphc_ctx_is_active(const struct lowpan_iphc_ctx *ctx)
{
return test_bit(LOWPAN_IPHC_CTX_FLAG_ACTIVE, &ctx->flags);
}
static inline bool
lowpan_iphc_ctx_is_compression(const struct lowpan_iphc_ctx *ctx)
{
return test_bit(LOWPAN_IPHC_CTX_FLAG_COMPRESSION, &ctx->flags);
}
struct lowpan_dev {
enum lowpan_lltypes lltype;
struct dentry *iface_debugfs;
struct lowpan_iphc_ctx_table ctx;
/* must be last */
u8 priv[] __aligned(sizeof(void *));
};
struct lowpan_802154_neigh {
__le16 short_addr;
};
static inline
struct lowpan_802154_neigh *lowpan_802154_neigh(void *neigh_priv)
{
return neigh_priv;
}
static inline
struct lowpan_dev *lowpan_dev(const struct net_device *dev)
{
return netdev_priv(dev);
}
/* private device info */
struct lowpan_802154_dev {
struct net_device *wdev; /* wpan device ptr */
u16 fragment_tag;
};
static inline struct
lowpan_802154_dev *lowpan_802154_dev(const struct net_device *dev)
{
return (struct lowpan_802154_dev *)lowpan_dev(dev)->priv;
}
struct lowpan_802154_cb {
u16 d_tag;
unsigned int d_size;
u8 d_offset;
};
static inline
struct lowpan_802154_cb *lowpan_802154_cb(const struct sk_buff *skb)
{
BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(skb->cb));
return (struct lowpan_802154_cb *)skb->cb;
}
static inline void lowpan_iphc_uncompress_eui64_lladdr(struct in6_addr *ipaddr,
const void *lladdr)
{
/* fe:80::XXXX:XXXX:XXXX:XXXX
* \_________________/
* hwaddr
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
memcpy(&ipaddr->s6_addr[8], lladdr, EUI64_ADDR_LEN);
/* second bit-flip (Universe/Local)
* is done according RFC2464
*/
ipaddr->s6_addr[8] ^= 0x02;
}
static inline void lowpan_iphc_uncompress_eui48_lladdr(struct in6_addr *ipaddr,
const void *lladdr)
{
/* fe:80::XXXX:XXff:feXX:XXXX
* \_________________/
* hwaddr
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
memcpy(&ipaddr->s6_addr[8], lladdr, 3);
ipaddr->s6_addr[11] = 0xFF;
ipaddr->s6_addr[12] = 0xFE;
memcpy(&ipaddr->s6_addr[13], lladdr + 3, 3);
}
#ifdef DEBUG
/* print data in line */
static inline void raw_dump_inline(const char *caller, char *msg,
const unsigned char *buf, int len)
{
if (msg)
pr_debug("%s():%s: ", caller, msg);
print_hex_dump_debug("", DUMP_PREFIX_NONE, 16, 1, buf, len, false);
}
/* print data in a table format:
*
* addr: xx xx xx xx xx xx
* addr: xx xx xx xx xx xx
* ...
*/
static inline void raw_dump_table(const char *caller, char *msg,
const unsigned char *buf, int len)
{
if (msg)
pr_debug("%s():%s:\n", caller, msg);
print_hex_dump_debug("\t", DUMP_PREFIX_OFFSET, 16, 1, buf, len, false);
}
#else
static inline void raw_dump_table(const char *caller, char *msg,
const unsigned char *buf, int len) { }
static inline void raw_dump_inline(const char *caller, char *msg,
const unsigned char *buf, int len) { }
#endif
/**
* lowpan_fetch_skb - getting inline data from 6LoWPAN header
*
* This function will pull data from sk buffer and put it into data to
* remove the 6LoWPAN inline data. This function returns true if the
* sk buffer is too small to pull the amount of data which is specified
* by len.
*
* @skb: the buffer where the inline data should be pulled from.
* @data: destination buffer for the inline data.
* @len: amount of data which should be pulled in bytes.
*/
static inline bool lowpan_fetch_skb(struct sk_buff *skb, void *data,
unsigned int len)
{
if (unlikely(!pskb_may_pull(skb, len)))
return true;
skb_copy_from_linear_data(skb, data, len);
skb_pull(skb, len);
return false;
}
static inline bool lowpan_802154_is_valid_src_short_addr(__le16 addr)
{
/* First bit of addr is multicast, reserved or 802.15.4 specific */
return !(addr & cpu_to_le16(0x8000));
}
static inline void lowpan_push_hc_data(u8 **hc_ptr, const void *data,
const size_t len)
{
memcpy(*hc_ptr, data, len);
*hc_ptr += len;
}
int lowpan_register_netdevice(struct net_device *dev,
enum lowpan_lltypes lltype);
int lowpan_register_netdev(struct net_device *dev,
enum lowpan_lltypes lltype);
void lowpan_unregister_netdevice(struct net_device *dev);
void lowpan_unregister_netdev(struct net_device *dev);
/**
* lowpan_header_decompress - replace 6LoWPAN header with IPv6 header
*
* This function replaces the IPHC 6LoWPAN header which should be pointed at
* skb->data and skb_network_header, with the IPv6 header.
* It would be nice that the caller have the necessary headroom of IPv6 header
* and greatest Transport layer header, this would reduce the overhead for
* reallocate headroom.
*
* @skb: the buffer which should be manipulate.
* @dev: the lowpan net device pointer.
* @daddr: destination lladdr of mac header which is used for compression
* methods.
* @saddr: source lladdr of mac header which is used for compression
* methods.
*/
int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
const void *daddr, const void *saddr);
/**
* lowpan_header_compress - replace IPv6 header with 6LoWPAN header
*
* This function replaces the IPv6 header which should be pointed at
* skb->data and skb_network_header, with the IPHC 6LoWPAN header.
* The caller need to be sure that the sk buffer is not shared and at have
* at least a headroom which is smaller or equal LOWPAN_IPHC_MAX_HEADER_LEN,
* which is the IPHC "more bytes than IPv6 header" at worst case.
*
* @skb: the buffer which should be manipulate.
* @dev: the lowpan net device pointer.
* @daddr: destination lladdr of mac header which is used for compression
* methods.
* @saddr: source lladdr of mac header which is used for compression
* methods.
*/
int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
const void *daddr, const void *saddr);
#endif /* __6LOWPAN_H__ */