netfilter: nfnetlink_{log,queue}: Register pernet in first place

nfnetlink_{log,queue}_init() register the netlink callback nf*_rcv_nl_event
before registering the pernet_subsys, but the callback relies on data
structures allocated by pernet init functions.

When nfnetlink_{log,queue} is loaded, if a netlink message is received after
the netlink callback is registered but before the pernet_subsys is registered,
the kernel will panic in the sequence

nfulnl_rcv_nl_event
  nfnl_log_pernet
    net_generic
      BUG_ON(id == 0)  where id is nfnl_log_net_id.

The panic can be easily reproduced in 4.0.3 by:

while true ;do modprobe nfnetlink_log ; rmmod nfnetlink_log ; done &
while true ;do ip netns add dummy ; ip netns del dummy ; done &

This patch moves register_pernet_subsys to earlier in nfnetlink_log_init.

Notice that the BUG_ON hit in 4.0.3 was recently removed in 2591ffd308
["netns: remove BUG_ONs from net_generic()"].

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 19 insertions, 18 deletions

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 3ad91266c821..4ef1fae8445e 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -1073,7 +1073,13 @@ static struct pernet_operations nfnl_log_net_ops = {
 
 static int __init nfnetlink_log_init(void)
 {
-        int status = -ENOMEM;
+        int status;
+
+        status = register_pernet_subsys(&nfnl_log_net_ops);
+        if (status < 0) {
+                pr_err("failed to register pernet ops\n");
+                goto out;
+        }
 
         netlink_register_notifier(&nfulnl_rtnl_notifier);
         status = nfnetlink_subsys_register(&nfulnl_subsys);
@@ -1088,28 +1094,23 @@ static int __init nfnetlink_log_init(void)
                 goto cleanup_subsys;
         }
 
-        status = register_pernet_subsys(&nfnl_log_net_ops);
-        if (status < 0) {
-                pr_err("failed to register pernet ops\n");
-                goto cleanup_logger;
-        }
         return status;
 
-cleanup_logger:
-        nf_log_unregister(&nfulnl_logger);
 cleanup_subsys:
         nfnetlink_subsys_unregister(&nfulnl_subsys);
 cleanup_netlink_notifier:
         netlink_unregister_notifier(&nfulnl_rtnl_notifier);
+        unregister_pernet_subsys(&nfnl_log_net_ops);
+out:
         return status;
 }
 
 static void __exit nfnetlink_log_fini(void)
 {
-        unregister_pernet_subsys(&nfnl_log_net_ops);
         nf_log_unregister(&nfulnl_logger);
         nfnetlink_subsys_unregister(&nfulnl_subsys);
         netlink_unregister_notifier(&nfulnl_rtnl_notifier);
+        unregister_pernet_subsys(&nfnl_log_net_ops);
 }
 
 MODULE_DESCRIPTION("netfilter userspace logging");
diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c
index 0b98c7420239..11c7682fa0ea 100644
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -1317,7 +1317,13 @@ static struct pernet_operations nfnl_queue_net_ops = {
 
 static int __init nfnetlink_queue_init(void)
 {
-        int status = -ENOMEM;
+        int status;
+
+        status = register_pernet_subsys(&nfnl_queue_net_ops);
+        if (status < 0) {
+                pr_err("nf_queue: failed to register pernet ops\n");
+                goto out;
+        }
 
         netlink_register_notifier(&nfqnl_rtnl_notifier);
         status = nfnetlink_subsys_register(&nfqnl_subsys);
@@ -1326,19 +1332,13 @@ static int __init nfnetlink_queue_init(void)
                 goto cleanup_netlink_notifier;
         }
 
-        status = register_pernet_subsys(&nfnl_queue_net_ops);
-        if (status < 0) {
-                pr_err("nf_queue: failed to register pernet ops\n");
-                goto cleanup_subsys;
-        }
         register_netdevice_notifier(&nfqnl_dev_notifier);
         nf_register_queue_handler(&nfqh);
         return status;
 
-cleanup_subsys:
-        nfnetlink_subsys_unregister(&nfqnl_subsys);
 cleanup_netlink_notifier:
         netlink_unregister_notifier(&nfqnl_rtnl_notifier);
+out:
         return status;
 }
 
@@ -1346,9 +1346,9 @@ static void __exit nfnetlink_queue_fini(void)
 {
         nf_unregister_queue_handler();
         unregister_netdevice_notifier(&nfqnl_dev_notifier);
-        unregister_pernet_subsys(&nfnl_queue_net_ops);
         nfnetlink_subsys_unregister(&nfqnl_subsys);
         netlink_unregister_notifier(&nfqnl_rtnl_notifier);
+        unregister_pernet_subsys(&nfnl_queue_net_ops);
 
         rcu_barrier(); /* Wait for completion of call_rcu()'s */
 }