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netfilter: add and use jump label for xt_tee 

Don't bother testing if we need to switch to alternate stack
unless TEE target is used.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2015-07-14 17:51:09 +02:00 committed by Pablo Neira Ayuso
parent 7814b6ec6d
commit dcebd3153e
5 changed files with 16 additions and 2 deletions
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7
include/linux/netfilter/x_tables.h
View File

@ -3,6 +3,7 @@
#include <linux/netdevice.h>
#include <linux/static_key.h>
#include <uapi/linux/netfilter/x_tables.h>
/**
@ -280,6 +281,12 @@ void xt_free_table_info(struct xt_table_info *info);
*/
DECLARE_PER_CPU(seqcount_t, xt_recseq);
/* xt_tee_enabled - true if x_tables needs to handle reentrancy
*
* Enabled if current ip(6)tables ruleset has at least one -j TEE rule.
*/
extern struct static_key xt_tee_enabled;
/**
* xt_write_recseq_begin - start of a write section
*

3
net/ipv4/netfilter/ip_tables.c
View File

@ -340,7 +340,8 @@ ipt_do_table(struct sk_buff *skb,
* For recursion via REJECT or SYNPROXY the stack will be clobbered
* but it is no problem since absolute verdict is issued by these.
*/
jumpstack += private->stacksize * __this_cpu_read(nf_skb_duplicated);
if (static_key_false(&xt_tee_enabled))
jumpstack += private->stacksize * __this_cpu_read(nf_skb_duplicated);
e = get_entry(table_base, private->hook_entry[hook]);

3
net/ipv6/netfilter/ip6_tables.c
View File

@ -366,7 +366,8 @@ ip6t_do_table(struct sk_buff *skb,
* For recursion via REJECT or SYNPROXY the stack will be clobbered
* but it is no problem since absolute verdict is issued by these.
*/
jumpstack += private->stacksize * __this_cpu_read(nf_skb_duplicated);
if (static_key_false(&xt_tee_enabled))
jumpstack += private->stacksize * __this_cpu_read(nf_skb_duplicated);
e = get_entry(table_base, private->hook_entry[hook]);

3
net/netfilter/x_tables.c
View File

@ -727,6 +727,9 @@ EXPORT_SYMBOL_GPL(xt_compat_unlock);
DEFINE_PER_CPU(seqcount_t, xt_recseq);
EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);
struct static_key xt_tee_enabled __read_mostly;
EXPORT_SYMBOL_GPL(xt_tee_enabled);
static int xt_jumpstack_alloc(struct xt_table_info *i)
{
unsigned int size;

2
net/netfilter/xt_TEE.c
View File

@ -251,6 +251,7 @@ static int tee_tg_check(const struct xt_tgchk_param *par)
} else
info->priv = NULL;
static_key_slow_inc(&xt_tee_enabled);
return 0;
}
@ -262,6 +263,7 @@ static void tee_tg_destroy(const struct xt_tgdtor_param *par)
unregister_netdevice_notifier(&info->priv->notifier);
kfree(info->priv);
}
static_key_slow_dec(&xt_tee_enabled);
}
static struct xt_target tee_tg_reg[] __read_mostly = {