Commit 834184b1 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso

netfilter: defrag: only register defrag functionality if needed

nf_defrag modules for ipv4 and ipv6 export an empty stub function.
Any module that needs the defragmentation hooks registered simply 'calls'
this empty function to create a phony module dependency -- modprobe will
then load the defrag module too.

This extends netfilter ipv4/ipv6 defragmentation modules to delay the hook
registration until the functionality is requested within a network namespace
instead of module load time for all namespaces.

Hooks are only un-registered on module unload or when a namespace that used
such defrag functionality exits.

We have to use struct net for this as the register hooks can be called
before netns initialization here from the ipv4/ipv6 conntrack module
init path.

There is no unregister functionality support, defrag will always be
active once it was requested inside a net namespace.

The reason is that defrag has impact on nft and iptables rulesets
(without defrag we might see framents).
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 481fa373
#ifndef _NF_DEFRAG_IPV4_H
#define _NF_DEFRAG_IPV4_H
void nf_defrag_ipv4_enable(void);
struct net;
int nf_defrag_ipv4_enable(struct net *);
#endif /* _NF_DEFRAG_IPV4_H */
#ifndef _NF_DEFRAG_IPV6_H
#define _NF_DEFRAG_IPV6_H
void nf_defrag_ipv6_enable(void);
struct net;
int nf_defrag_ipv6_enable(struct net *);
int nf_ct_frag6_init(void);
void nf_ct_frag6_cleanup(void);
......
......@@ -17,5 +17,11 @@ struct netns_nf {
struct ctl_table_header *nf_log_dir_header;
#endif
struct nf_hook_entry __rcu *hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
bool defrag_ipv4;
#endif
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
bool defrag_ipv6;
#endif
};
#endif
......@@ -325,6 +325,12 @@ static int ipv4_hooks_register(struct net *net)
if (cnet->users > 1)
goto out_unlock;
err = nf_defrag_ipv4_enable(net);
if (err) {
cnet->users = 0;
goto out_unlock;
}
err = nf_register_net_hooks(net, ipv4_conntrack_ops,
ARRAY_SIZE(ipv4_conntrack_ops));
......@@ -422,7 +428,6 @@ static int __init nf_conntrack_l3proto_ipv4_init(void)
int ret = 0;
need_conntrack();
nf_defrag_ipv4_enable();
ret = nf_register_sockopt(&so_getorigdst);
if (ret < 0) {
......
......@@ -11,6 +11,7 @@
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/netns/generic.h>
#include <net/route.h>
#include <net/ip.h>
......@@ -22,6 +23,8 @@
#endif
#include <net/netfilter/nf_conntrack_zones.h>
static DEFINE_MUTEX(defrag4_mutex);
static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
u_int32_t user)
{
......@@ -102,18 +105,50 @@ static struct nf_hook_ops ipv4_defrag_ops[] = {
},
};
static void __net_exit defrag4_net_exit(struct net *net)
{
if (net->nf.defrag_ipv4) {
nf_unregister_net_hooks(net, ipv4_defrag_ops,
ARRAY_SIZE(ipv4_defrag_ops));
net->nf.defrag_ipv4 = false;
}
}
static struct pernet_operations defrag4_net_ops = {
.exit = defrag4_net_exit,
};
static int __init nf_defrag_init(void)
{
return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
return register_pernet_subsys(&defrag4_net_ops);
}
static void __exit nf_defrag_fini(void)
{
nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
unregister_pernet_subsys(&defrag4_net_ops);
}
void nf_defrag_ipv4_enable(void)
int nf_defrag_ipv4_enable(struct net *net)
{
int err = 0;
might_sleep();
if (net->nf.defrag_ipv4)
return 0;
mutex_lock(&defrag4_mutex);
if (net->nf.defrag_ipv4)
goto out_unlock;
err = nf_register_net_hooks(net, ipv4_defrag_ops,
ARRAY_SIZE(ipv4_defrag_ops));
if (err == 0)
net->nf.defrag_ipv4 = true;
out_unlock:
mutex_unlock(&defrag4_mutex);
return err;
}
EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
......
......@@ -325,6 +325,12 @@ static int ipv6_hooks_register(struct net *net)
if (cnet->users > 1)
goto out_unlock;
err = nf_defrag_ipv6_enable(net);
if (err < 0) {
cnet->users = 0;
goto out_unlock;
}
err = nf_register_net_hooks(net, ipv6_conntrack_ops,
ARRAY_SIZE(ipv6_conntrack_ops));
if (err)
......@@ -427,7 +433,6 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
int ret = 0;
need_conntrack();
nf_defrag_ipv6_enable();
ret = nf_register_sockopt(&so_getorigdst6);
if (ret < 0) {
......
......@@ -30,6 +30,8 @@
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
static DEFINE_MUTEX(defrag6_mutex);
static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
struct sk_buff *skb)
{
......@@ -87,6 +89,19 @@ static struct nf_hook_ops ipv6_defrag_ops[] = {
},
};
static void __net_exit defrag6_net_exit(struct net *net)
{
if (net->nf.defrag_ipv6) {
nf_unregister_net_hooks(net, ipv6_defrag_ops,
ARRAY_SIZE(ipv6_defrag_ops));
net->nf.defrag_ipv6 = false;
}
}
static struct pernet_operations defrag6_net_ops = {
.exit = defrag6_net_exit,
};
static int __init nf_defrag_init(void)
{
int ret = 0;
......@@ -96,9 +111,9 @@ static int __init nf_defrag_init(void)
pr_err("nf_defrag_ipv6: can't initialize frag6.\n");
return ret;
}
ret = nf_register_hooks(ipv6_defrag_ops, ARRAY_SIZE(ipv6_defrag_ops));
ret = register_pernet_subsys(&defrag6_net_ops);
if (ret < 0) {
pr_err("nf_defrag_ipv6: can't register hooks\n");
pr_err("nf_defrag_ipv6: can't register pernet ops\n");
goto cleanup_frag6;
}
return ret;
......@@ -111,12 +126,31 @@ static int __init nf_defrag_init(void)
static void __exit nf_defrag_fini(void)
{
nf_unregister_hooks(ipv6_defrag_ops, ARRAY_SIZE(ipv6_defrag_ops));
unregister_pernet_subsys(&defrag6_net_ops);
nf_ct_frag6_cleanup();
}
void nf_defrag_ipv6_enable(void)
int nf_defrag_ipv6_enable(struct net *net)
{
int err = 0;
might_sleep();
if (net->nf.defrag_ipv6)
return 0;
mutex_lock(&defrag6_mutex);
if (net->nf.defrag_ipv6)
goto out_unlock;
err = nf_register_net_hooks(net, ipv6_defrag_ops,
ARRAY_SIZE(ipv6_defrag_ops));
if (err == 0)
net->nf.defrag_ipv6 = true;
out_unlock:
mutex_unlock(&defrag6_mutex);
return err;
}
EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
......
......@@ -531,6 +531,11 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
static int tproxy_tg6_check(const struct xt_tgchk_param *par)
{
const struct ip6t_ip6 *i = par->entryinfo;
int err;
err = nf_defrag_ipv6_enable(par->net);
if (err)
return err;
if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) &&
!(i->invflags & IP6T_INV_PROTO))
......@@ -545,6 +550,11 @@ static int tproxy_tg6_check(const struct xt_tgchk_param *par)
static int tproxy_tg4_check(const struct xt_tgchk_param *par)
{
const struct ipt_ip *i = par->entryinfo;
int err;
err = nf_defrag_ipv4_enable(par->net);
if (err)
return err;
if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
&& !(i->invflags & IPT_INV_PROTO))
......@@ -596,11 +606,6 @@ static struct xt_target tproxy_tg_reg[] __read_mostly = {
static int __init tproxy_tg_init(void)
{
nf_defrag_ipv4_enable();
#ifdef XT_TPROXY_HAVE_IPV6
nf_defrag_ipv6_enable();
#endif
return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
}
......
......@@ -147,9 +147,28 @@ socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
}
#endif
static int socket_mt_enable_defrag(struct net *net, int family)
{
switch (family) {
case NFPROTO_IPV4:
return nf_defrag_ipv4_enable(net);
#ifdef XT_SOCKET_HAVE_IPV6
case NFPROTO_IPV6:
return nf_defrag_ipv6_enable(net);
#endif
}
WARN_ONCE(1, "Unknown family %d\n", family);
return 0;
}
static int socket_mt_v1_check(const struct xt_mtchk_param *par)
{
const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
int err;
err = socket_mt_enable_defrag(par->net, par->family);
if (err)
return err;
if (info->flags & ~XT_SOCKET_FLAGS_V1) {
pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
......@@ -161,6 +180,11 @@ static int socket_mt_v1_check(const struct xt_mtchk_param *par)
static int socket_mt_v2_check(const struct xt_mtchk_param *par)
{
const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
int err;
err = socket_mt_enable_defrag(par->net, par->family);
if (err)
return err;
if (info->flags & ~XT_SOCKET_FLAGS_V2) {
pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
......@@ -173,7 +197,11 @@ static int socket_mt_v3_check(const struct xt_mtchk_param *par)
{
const struct xt_socket_mtinfo3 *info =
(struct xt_socket_mtinfo3 *)par->matchinfo;
int err;
err = socket_mt_enable_defrag(par->net, par->family);
if (err)
return err;
if (info->flags & ~XT_SOCKET_FLAGS_V3) {
pr_info("unknown flags 0x%x\n",
info->flags & ~XT_SOCKET_FLAGS_V3);
......@@ -268,11 +296,6 @@ static struct xt_match socket_mt_reg[] __read_mostly = {
static int __init socket_mt_init(void)
{
nf_defrag_ipv4_enable();
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
nf_defrag_ipv6_enable();
#endif
return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
}
......
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