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netfilter: nf_conntrack: use l4proto->users as refcount for per-net data
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Currently, nf_proto_net's l4proto->users meaning is quite confusing
since it depends on the compilation tweaks.

To resolve this, we cleanup this code to regard it as the refcount
for l4proto's per-net data, since there may be two l4protos use the
same per-net data.

Thus, we increment pn->users when nf_conntrack_l4proto_register
successfully, and decrement it for nf_conntrack_l4_unregister case.

The users refcnt is not required form layer 3 protocol trackers.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Gao feng authored and Pablo Neira Ayuso committed Jun 27, 2012
1 parent f28997e commit fa34fff
Showing 1 changed file with 46 additions and 30 deletions.
76 changes: 46 additions & 30 deletions net/netfilter/nf_conntrack_proto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,26 +39,23 @@ static int
nf_ct_register_sysctl(struct net *net,
struct ctl_table_header **header,
const char *path,
struct ctl_table *table,
unsigned int *users)
struct ctl_table *table)
{
if (*header == NULL) {
*header = register_net_sysctl(net, path, table);
if (*header == NULL)
return -ENOMEM;
}
if (users != NULL)
(*users)++;

return 0;
}

static void
nf_ct_unregister_sysctl(struct ctl_table_header **header,
struct ctl_table **table,
unsigned int *users)
unsigned int users)
{
if (users != NULL && --*users > 0)
if (users > 0)
return;

unregister_net_sysctl_table(*header);
Expand Down Expand Up @@ -191,8 +188,7 @@ static int nf_ct_l3proto_register_sysctl(struct net *net,
err = nf_ct_register_sysctl(net,
&in->ctl_table_header,
l3proto->ctl_table_path,
in->ctl_table,
NULL);
in->ctl_table);
if (err < 0) {
kfree(in->ctl_table);
in->ctl_table = NULL;
Expand All @@ -213,7 +209,7 @@ static void nf_ct_l3proto_unregister_sysctl(struct net *net,
if (in->ctl_table_header != NULL)
nf_ct_unregister_sysctl(&in->ctl_table_header,
&in->ctl_table,
NULL);
0);
#endif
}

Expand Down Expand Up @@ -329,20 +325,17 @@ static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,

static
int nf_ct_l4proto_register_sysctl(struct net *net,
struct nf_proto_net *pn,
struct nf_conntrack_l4proto *l4proto)
{
int err = 0;
struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
if (pn == NULL)
return 0;

#ifdef CONFIG_SYSCTL
if (pn->ctl_table != NULL) {
err = nf_ct_register_sysctl(net,
&pn->ctl_table_header,
"net/netfilter",
pn->ctl_table,
&pn->users);
pn->ctl_table);
if (err < 0) {
if (!pn->users) {
kfree(pn->ctl_table);
Expand All @@ -356,15 +349,14 @@ int nf_ct_l4proto_register_sysctl(struct net *net,
err = nf_ct_register_sysctl(net,
&pn->ctl_compat_header,
"net/ipv4/netfilter",
pn->ctl_compat_table,
NULL);
pn->ctl_compat_table);
if (err == 0)
goto out;

nf_ct_kfree_compat_sysctl_table(pn);
nf_ct_unregister_sysctl(&pn->ctl_table_header,
&pn->ctl_table,
&pn->users);
pn->users);
}
#endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
out:
Expand All @@ -374,25 +366,21 @@ int nf_ct_l4proto_register_sysctl(struct net *net,

static
void nf_ct_l4proto_unregister_sysctl(struct net *net,
struct nf_proto_net *pn,
struct nf_conntrack_l4proto *l4proto)
{
struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
if (pn == NULL)
return;
#ifdef CONFIG_SYSCTL
if (pn->ctl_table_header != NULL)
nf_ct_unregister_sysctl(&pn->ctl_table_header,
&pn->ctl_table,
&pn->users);
pn->users);

#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
nf_ct_unregister_sysctl(&pn->ctl_compat_header,
&pn->ctl_compat_table,
NULL);
0);
#endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
#else
pn->users--;
#endif /* CONFIG_SYSCTL */
}

Expand Down Expand Up @@ -458,23 +446,32 @@ int nf_conntrack_l4proto_register(struct net *net,
struct nf_conntrack_l4proto *l4proto)
{
int ret = 0;
struct nf_proto_net *pn = NULL;

if (l4proto->init_net) {
ret = l4proto->init_net(net, l4proto->l3proto);
if (ret < 0)
return ret;
goto out;
}

ret = nf_ct_l4proto_register_sysctl(net, l4proto);
pn = nf_ct_l4proto_net(net, l4proto);
if (pn == NULL)
goto out;

ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
if (ret < 0)
return ret;
goto out;

if (net == &init_net) {
ret = nf_conntrack_l4proto_register_net(l4proto);
if (ret < 0)
nf_ct_l4proto_unregister_sysctl(net, l4proto);
if (ret < 0) {
nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
goto out;
}
}

pn->users++;
out:
return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
Expand All @@ -499,10 +496,18 @@ nf_conntrack_l4proto_unregister_net(struct nf_conntrack_l4proto *l4proto)
void nf_conntrack_l4proto_unregister(struct net *net,
struct nf_conntrack_l4proto *l4proto)
{
struct nf_proto_net *pn = NULL;

if (net == &init_net)
nf_conntrack_l4proto_unregister_net(l4proto);

nf_ct_l4proto_unregister_sysctl(net, l4proto);
pn = nf_ct_l4proto_net(net, l4proto);
if (pn == NULL)
return;

pn->users--;
nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);

/* Remove all contrack entries for this protocol */
rtnl_lock();
nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
Expand All @@ -514,11 +519,15 @@ int nf_conntrack_proto_init(struct net *net)
{
unsigned int i;
int err;
struct nf_proto_net *pn = nf_ct_l4proto_net(net,
&nf_conntrack_l4proto_generic);

err = nf_conntrack_l4proto_generic.init_net(net,
nf_conntrack_l4proto_generic.l3proto);
if (err < 0)
return err;
err = nf_ct_l4proto_register_sysctl(net,
pn,
&nf_conntrack_l4proto_generic);
if (err < 0)
return err;
Expand All @@ -528,13 +537,20 @@ int nf_conntrack_proto_init(struct net *net)
rcu_assign_pointer(nf_ct_l3protos[i],
&nf_conntrack_l3proto_generic);
}

pn->users++;
return 0;
}

void nf_conntrack_proto_fini(struct net *net)
{
unsigned int i;
struct nf_proto_net *pn = nf_ct_l4proto_net(net,
&nf_conntrack_l4proto_generic);

pn->users--;
nf_ct_l4proto_unregister_sysctl(net,
pn,
&nf_conntrack_l4proto_generic);
if (net == &init_net) {
/* free l3proto protocol tables */
Expand Down

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