[ 030/187] ipv6: Move ipv6 proc file registration to end of init order

Greg Kroah-Hartman
2012-07-12T23:47:35Z

From: Thomas Graf <tgraf@suug.ch>

[ Upstream commit d189634ecab947c10f6f832258b103d0bbfe73cc ]

/proc/net/ipv6_route reflects the contents of fib_table_hash. The proc
handler is installed in ip6_route_net_init() whereas fib_table_hash is
allocated in fib6_net_init() _after_ the proc handler has been installed.

This opens up a short time frame to access fib_table_hash with its pants
down.

Move the registration of the proc files to a later point in the init
order to avoid the race.

Tested :-)

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/route.c | 41 +++++++++++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 10 deletions(-)

--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2953,10 +2953,6 @@ static int __net_init ip6_route_net_init
net->ipv6.sysctl.ip6_rt_mtu_expires = 10*60*HZ;
net->ipv6.sysctl.ip6_rt_min_advmss = IPV6_MIN_MTU - 20 - 40;

-#ifdef CONFIG_PROC_FS
- proc_net_fops_create(net, "ipv6_route", 0, &ipv6_route_proc_fops);
- proc_net_fops_create(net, "rt6_stats", S_IRUGO, &rt6_stats_seq_fops);
-#endif
net->ipv6.ip6_rt_gc_expire = 30*HZ;

ret = 0;
@@ -2977,10 +2973,6 @@ out_ip6_dst_ops:

static void __net_exit ip6_route_net_exit(struct net *net)
{
-#ifdef CONFIG_PROC_FS
- proc_net_remove(net, "ipv6_route");
- proc_net_remove(net, "rt6_stats");
-#endif
kfree(net->ipv6.ip6_null_entry);
#ifdef CONFIG_IPV6_MULTIPLE_TABLES
kfree(net->ipv6.ip6_prohibit_entry);
@@ -2989,11 +2981,33 @@ static void __net_exit ip6_route_net_exi
dst_entries_destroy(&net->ipv6.ip6_dst_ops);
}

+static int __net_init ip6_route_net_init_late(struct net *net)
+{
+#ifdef CONFIG_PROC_FS
+ proc_net_fops_create(net, "ipv6_route", 0, &ipv6_route_proc_fops);
+ proc_net_fops_create(net, "rt6_stats", S_IRUGO, &rt6_stats_seq_fops);
+#endif
+ return 0;
+}
+
+static void __net_exit ip6_route_net_exit_late(struct net *net)
+{
+#ifdef CONFIG_PROC_FS
+ proc_net_remove(net, "ipv6_route");
+ proc_net_remove(net, "rt6_stats");
+#endif
+}
+
static struct pernet_operations ip6_route_net_ops = {
.init = ip6_route_net_init,
.exit = ip6_route_net_exit,
};

+static struct pernet_operations ip6_route_net_late_ops = {
+ .init = ip6_route_net_init_late,
+ .exit = ip6_route_net_exit_late,
+};
+
static struct notifier_block ip6_route_dev_notifier = {
.notifier_call = ip6_route_dev_notify,
.priority = 0,
@@ -3043,19 +3057,25 @@ int __init ip6_route_init(void)
if (ret)
goto xfrm6_init;

+ ret = register_pernet_subsys(&ip6_route_net_late_ops);
+ if (ret)
+ goto fib6_rules_init;
+
ret = -ENOBUFS;
if (__rtnl_register(PF_INET6, RTM_NEWROUTE, inet6_rtm_newroute, NULL, NULL) ||
__rtnl_register(PF_INET6, RTM_DELROUTE, inet6_rtm_delroute, NULL, NULL) ||
__rtnl_register(PF_INET6, RTM_GETROUTE, inet6_rtm_getroute, NULL, NULL))
- goto fib6_rules_init;
+ goto out_register_late_subsys;

ret = register_netdevice_notifier(&ip6_route_dev_notifier);
if (ret)
- goto fib6_rules_init;
+ goto out_register_late_subsys;

out:
return ret;

+out_register_late_subsys:
+ unregister_pernet_subsys(&ip6_route_net_late_ops);
fib6_rules_init:
fib6_rules_cleanup();
xfrm6_init:
@@ -3074,6 +3094,7 @@ out_kmem_cache:
void ip6_route_cleanup(void)
{
unregister_netdevice_notifier(&ip6_route_dev_notifier);
+ unregister_pernet_subsys(&ip6_route_net_late_ops);
fib6_rules_cleanup();
xfrm6_fini();
fib6_gc_cleanup();