7c96643519
The nat extension structure is 32bytes in size on x86_64:
struct nf_conn_nat {
struct hlist_node bysource; /* 0 16 */
struct nf_conn * ct; /* 16 8 */
union nf_conntrack_nat_help help; /* 24 4 */
int masq_index; /* 28 4 */
/* size: 32, cachelines: 1, members: 4 */
/* last cacheline: 32 bytes */
};
The hlist is needed to quickly check for possible tuple collisions
when installing a new nat binding. Storing this in the extension
area has two drawbacks:
1. We need ct backpointer to get the conntrack struct from the extension.
2. When reallocation of extension area occurs we need to fixup the bysource
hash head via hlist_replace_rcu.
We can avoid both by placing the hlist_head in nf_conn and place nf_conn in
the bysource hash rather than the extenstion.
We can also remove the ->move support; no other extension needs it.
Moving the entire nat extension into nf_conn would be possible as well but
then we have to add yet another callback for deletion from the bysource
hash table rather than just using nat extension ->destroy hook for this.
nf_conn size doesn't increase due to aligment, followup patch replaces
hlist_node with single pointer.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
117 lines
2.9 KiB
C
117 lines
2.9 KiB
C
#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 defined(CONFIG_NF_NAT) || defined(CONFIG_NF_NAT_MODULE)
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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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struct rcu_head rcu;
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u16 offset[NF_CT_EXT_NUM];
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u16 len;
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char data[0];
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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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static inline void nf_ct_ext_destroy(struct nf_conn *ct)
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{
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if (ct->ext)
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__nf_ct_ext_destroy(ct);
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}
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/* Free operation. If you want to free a object referred from private area,
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* please implement __nf_ct_ext_free() and call it.
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*/
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static inline void nf_ct_ext_free(struct nf_conn *ct)
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{
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if (ct->ext)
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kfree_rcu(ct->ext, rcu);
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}
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/* Add this type, returns pointer to data or NULL. */
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void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id,
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size_t var_alloc_len, gfp_t gfp);
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#define nf_ct_ext_add(ct, id, gfp) \
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((id##_TYPE *)__nf_ct_ext_add_length((ct), (id), 0, (gfp)))
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#define nf_ct_ext_add_length(ct, id, len, gfp) \
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((id##_TYPE *)__nf_ct_ext_add_length((ct), (id), (len), (gfp)))
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#define NF_CT_EXT_F_PREALLOC 0x0001
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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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unsigned int flags;
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/* Length and min alignment. */
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u8 len;
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u8 align;
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/* initial size of nf_ct_ext. */
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u8 alloc_size;
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};
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int nf_ct_extend_register(struct nf_ct_ext_type *type);
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void nf_ct_extend_unregister(struct nf_ct_ext_type *type);
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#endif /* _NF_CONNTRACK_EXTEND_H */
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