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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>
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||
|---|---|---|
| .. | ||
| ipv4 | ||
| ipv6 | ||
| br_netfilter.h | ||
| nf_conntrack.h | ||
| nf_conntrack_acct.h | ||
| nf_conntrack_core.h | ||
| nf_conntrack_ecache.h | ||
| nf_conntrack_expect.h | ||
| nf_conntrack_extend.h | ||
| nf_conntrack_helper.h | ||
| nf_conntrack_l3proto.h | ||
| nf_conntrack_l4proto.h | ||
| nf_conntrack_labels.h | ||
| nf_conntrack_seqadj.h | ||
| nf_conntrack_synproxy.h | ||
| nf_conntrack_timeout.h | ||
| nf_conntrack_timestamp.h | ||
| nf_conntrack_tuple.h | ||
| nf_conntrack_zones.h | ||
| nf_dup_netdev.h | ||
| nf_log.h | ||
| nf_nat.h | ||
| nf_nat_core.h | ||
| nf_nat_helper.h | ||
| nf_nat_l3proto.h | ||
| nf_nat_l4proto.h | ||
| nf_nat_redirect.h | ||
| nf_queue.h | ||
| nf_tables.h | ||
| nf_tables_bridge.h | ||
| nf_tables_core.h | ||
| nf_tables_ipv4.h | ||
| nf_tables_ipv6.h | ||
| nfnetlink_log.h | ||
| nft_dup.h | ||
| nft_masq.h | ||
| nft_meta.h | ||
| nft_redir.h | ||
| nft_reject.h | ||
| xt_rateest.h | ||