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>
91 lines
2.2 KiB
C
91 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _NF_CONNTRACK_EXTEND_H
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#define _NF_CONNTRACK_EXTEND_H
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#include <linux/slab.h>
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#include <net/netfilter/nf_conntrack.h>
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enum nf_ct_ext_id {
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NF_CT_EXT_HELPER,
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#if IS_ENABLED(CONFIG_NF_NAT)
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NF_CT_EXT_NAT,
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#endif
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NF_CT_EXT_SEQADJ,
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NF_CT_EXT_ACCT,
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#ifdef CONFIG_NF_CONNTRACK_EVENTS
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NF_CT_EXT_ECACHE,
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#endif
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#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
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NF_CT_EXT_TSTAMP,
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#endif
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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NF_CT_EXT_TIMEOUT,
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#endif
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#ifdef CONFIG_NF_CONNTRACK_LABELS
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NF_CT_EXT_LABELS,
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#endif
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#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
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NF_CT_EXT_SYNPROXY,
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#endif
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NF_CT_EXT_NUM,
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};
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#define NF_CT_EXT_HELPER_TYPE struct nf_conn_help
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#define NF_CT_EXT_NAT_TYPE struct nf_conn_nat
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#define NF_CT_EXT_SEQADJ_TYPE struct nf_conn_seqadj
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#define NF_CT_EXT_ACCT_TYPE struct nf_conn_acct
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#define NF_CT_EXT_ECACHE_TYPE struct nf_conntrack_ecache
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#define NF_CT_EXT_TSTAMP_TYPE struct nf_conn_tstamp
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#define NF_CT_EXT_TIMEOUT_TYPE struct nf_conn_timeout
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#define NF_CT_EXT_LABELS_TYPE struct nf_conn_labels
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#define NF_CT_EXT_SYNPROXY_TYPE struct nf_conn_synproxy
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/* Extensions: optional stuff which isn't permanently in struct. */
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struct nf_ct_ext {
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u8 offset[NF_CT_EXT_NUM];
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u8 len;
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char data[];
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};
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static inline bool __nf_ct_ext_exist(const struct nf_ct_ext *ext, u8 id)
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{
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return !!ext->offset[id];
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}
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static inline bool nf_ct_ext_exist(const struct nf_conn *ct, u8 id)
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{
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return (ct->ext && __nf_ct_ext_exist(ct->ext, id));
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}
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static inline void *__nf_ct_ext_find(const struct nf_conn *ct, u8 id)
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{
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if (!nf_ct_ext_exist(ct, id))
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return NULL;
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return (void *)ct->ext + ct->ext->offset[id];
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}
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#define nf_ct_ext_find(ext, id) \
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((id##_TYPE *)__nf_ct_ext_find((ext), (id)))
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/* Destroy all relationships */
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void nf_ct_ext_destroy(struct nf_conn *ct);
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/* Add this type, returns pointer to data or NULL. */
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void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp);
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struct nf_ct_ext_type {
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/* Destroys relationships (can be NULL). */
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void (*destroy)(struct nf_conn *ct);
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enum nf_ct_ext_id id;
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/* Length and min alignment. */
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u8 len;
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u8 align;
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};
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int nf_ct_extend_register(const struct nf_ct_ext_type *type);
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void nf_ct_extend_unregister(const struct nf_ct_ext_type *type);
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#endif /* _NF_CONNTRACK_EXTEND_H */
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