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[NETFILTER]: Properly use RCU in nf_ct_attach

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Use rcu_assign_pointer/rcu_dereference for ip_ct_attach pointer instead
of self-made RCU and use rcu_read_lock to make sure the conntrack module
doesn't disappear below us while calling it, since this function can be
called from outside the netfilter hooks.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2007-02-12 11:09:19 -08:00 committed by David S. Miller
parent ebaf0c6032
commit c3a47ab3e5
3 changed files with 10 additions and 7 deletions
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4
net/ipv4/netfilter/ip_conntrack_core.c
View File

@ -1354,7 +1354,7 @@ static void free_conntrack_hash(struct list_head *hash, int vmalloced,int size)
supposed to kill the mall. */
void ip_conntrack_cleanup(void)
{
ip_ct_attach = NULL;
rcu_assign_pointer(ip_ct_attach, NULL);
/* This makes sure all current packets have passed through
netfilter framework. Roll on, two-stage module
@ -1515,7 +1515,7 @@ int __init ip_conntrack_init(void)
write_unlock_bh(&ip_conntrack_lock);
/* For use by ipt_REJECT */
ip_ct_attach = ip_conntrack_attach;
rcu_assign_pointer(ip_ct_attach, ip_conntrack_attach);
/* Set up fake conntrack:
- to never be deleted, not in any hashes */

9
net/netfilter/core.c
View File

@ -248,9 +248,12 @@ void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
{
void (*attach)(struct sk_buff *, struct sk_buff *);
if (skb->nfct && (attach = ip_ct_attach) != NULL) {
mb(); /* Just to be sure: must be read before executing this */
attach(new, skb);
if (skb->nfct) {
rcu_read_lock();
attach = rcu_dereference(ip_ct_attach);
if (attach)
attach(new, skb);
rcu_read_unlock();
}
}
EXPORT_SYMBOL(nf_ct_attach);

4
net/netfilter/nf_conntrack_core.c
View File

@ -1105,7 +1105,7 @@ void nf_conntrack_cleanup(void)
{
int i;
ip_ct_attach = NULL;
rcu_assign_pointer(ip_ct_attach, NULL);
/* This makes sure all current packets have passed through
netfilter framework. Roll on, two-stage module
@ -1273,7 +1273,7 @@ int __init nf_conntrack_init(void)
write_unlock_bh(&nf_conntrack_lock);
/* For use by REJECT target */
ip_ct_attach = __nf_conntrack_attach;
rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach);
/* Set up fake conntrack:
- to never be deleted, not in any hashes */