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netfilter: iptables: Split ipt_unregister_table() into pre_exit and exit helpers.

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The pre_exit will un-register the underlying hook and .exit will do the
table freeing. The netns core does an unconditional synchronize_rcu after
the pre_exit hooks insuring no packets are in flight that have picked up
the pointer before completing the un-register.

Fixes: b9e69e1273 ("netfilter: xtables: don't hook tables by default")
Signed-off-by: David Wilder <dwilder@us.ibm.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
David Wilder 2020-06-22 10:10:11 -07:00 committed by Pablo Neira Ayuso
parent 4cacc39516
commit 1cbf90985f
2 changed files with 20 additions and 1 deletions
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6
include/linux/netfilter_ipv4/ip_tables.h
View file

@ -25,6 +25,12 @@
int ipt_register_table(struct net *net, const struct xt_table *table,
const struct ipt_replace *repl,
const struct nf_hook_ops *ops, struct xt_table **res);
void ipt_unregister_table_pre_exit(struct net *net, struct xt_table *table,
const struct nf_hook_ops *ops);
void ipt_unregister_table_exit(struct net *net, struct xt_table *table);
void ipt_unregister_table(struct net *net, struct xt_table *table,
const struct nf_hook_ops *ops);

15
net/ipv4/netfilter/ip_tables.c
View file

@ -1797,11 +1797,22 @@ int ipt_register_table(struct net *net, const struct xt_table *table,
return ret;
}
void ipt_unregister_table_pre_exit(struct net *net, struct xt_table *table,
const struct nf_hook_ops *ops)
{
nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
}
void ipt_unregister_table_exit(struct net *net, struct xt_table *table)
{
__ipt_unregister_table(net, table);
}
void ipt_unregister_table(struct net *net, struct xt_table *table,
const struct nf_hook_ops *ops)
{
if (ops)
nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
ipt_unregister_table_pre_exit(net, table, ops);
__ipt_unregister_table(net, table);
}
@ -1958,6 +1969,8 @@ static void __exit ip_tables_fini(void)
EXPORT_SYMBOL(ipt_register_table);
EXPORT_SYMBOL(ipt_unregister_table);
EXPORT_SYMBOL(ipt_unregister_table_pre_exit);
EXPORT_SYMBOL(ipt_unregister_table_exit);
EXPORT_SYMBOL(ipt_do_table);
module_init(ip_tables_init);
module_exit(ip_tables_fini);