6daf141401
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]
Lastly, fix checkpatch.pl warning
WARNING: __aligned(size) is preferred over __attribute__((aligned(size)))
in net/bridge/netfilter/ebtables.c
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: Pablo Neira Ayuso <pablo@netfilter.org>
81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Format of an ARP firewall descriptor
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*
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* src, tgt, src_mask, tgt_mask, arpop, arpop_mask are always stored in
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* network byte order.
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* flags are stored in host byte order (of course).
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*/
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#ifndef _ARPTABLES_H
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#define _ARPTABLES_H
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#include <linux/if.h>
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#include <linux/in.h>
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#include <linux/if_arp.h>
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#include <linux/skbuff.h>
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#include <uapi/linux/netfilter_arp/arp_tables.h>
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/* Standard entry. */
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struct arpt_standard {
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struct arpt_entry entry;
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struct xt_standard_target target;
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};
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struct arpt_error {
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struct arpt_entry entry;
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struct xt_error_target target;
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};
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#define ARPT_ENTRY_INIT(__size) \
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{ \
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.target_offset = sizeof(struct arpt_entry), \
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.next_offset = (__size), \
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}
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#define ARPT_STANDARD_INIT(__verdict) \
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{ \
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.entry = ARPT_ENTRY_INIT(sizeof(struct arpt_standard)), \
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.target = XT_TARGET_INIT(XT_STANDARD_TARGET, \
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sizeof(struct xt_standard_target)), \
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.target.verdict = -(__verdict) - 1, \
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}
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#define ARPT_ERROR_INIT \
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{ \
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.entry = ARPT_ENTRY_INIT(sizeof(struct arpt_error)), \
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.target = XT_TARGET_INIT(XT_ERROR_TARGET, \
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sizeof(struct xt_error_target)), \
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.target.errorname = "ERROR", \
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}
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extern void *arpt_alloc_initial_table(const struct xt_table *);
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int arpt_register_table(struct net *net, const struct xt_table *table,
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const struct arpt_replace *repl,
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const struct nf_hook_ops *ops, struct xt_table **res);
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void arpt_unregister_table(struct net *net, struct xt_table *table,
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const struct nf_hook_ops *ops);
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extern unsigned int arpt_do_table(struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct xt_table *table);
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#ifdef CONFIG_COMPAT
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#include <net/compat.h>
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struct compat_arpt_entry {
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struct arpt_arp arp;
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__u16 target_offset;
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__u16 next_offset;
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compat_uint_t comefrom;
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struct compat_xt_counters counters;
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unsigned char elems[];
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};
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static inline struct xt_entry_target *
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compat_arpt_get_target(struct compat_arpt_entry *e)
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{
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return (void *)e + e->target_offset;
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}
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#endif /* CONFIG_COMPAT */
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#endif /* _ARPTABLES_H */
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