net: support ns lookup

Support the generic ns lookup infrastructure to support file handles for
namespaces.

The network namespace has a separate list with different lifetime rules
which we can just leave in tact. We have a similar concept for mount
namespaces as well where it is on two differenet lists for different
purposes.

Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 5fb7bd8ac45afc26661135605a1c70333d5df3fc..169ec22c4758f40a992e101c2a49bf0a8e6dbee3 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -20,6 +20,7 @@
 #include <linux/sched/task.h>
 #include <linux/uidgid.h>
 #include <linux/proc_fs.h>
+#include <linux/nstree.h>
 
 #include <net/aligned_data.h>
 #include <net/sock.h>
@@ -445,7 +446,7 @@ static __net_init int setup_net(struct net *net)
        LIST_HEAD(net_exit_list);
        int error = 0;
 
-       net->net_cookie = atomic64_inc_return(&net_aligned_data.net_cookie);
+       net->net_cookie = ns_tree_gen_id(&net->ns);
 
        list_for_each_entry(ops, &pernet_list, list) {
                error = ops_init(ops, net);
@@ -455,6 +456,7 @@ static __net_init int setup_net(struct net *net)
        down_write(&net_rwsem);
        list_add_tail_rcu(&net->list, &net_namespace_list);
        up_write(&net_rwsem);
+       ns_tree_add_raw(net);
 out:
        return error;
 
@@ -674,8 +676,10 @@ static void cleanup_net(struct work_struct *work)
 
        /* Don't let anyone else find us. */
        down_write(&net_rwsem);
-       llist_for_each_entry(net, net_kill_list, cleanup_list)
+       llist_for_each_entry(net, net_kill_list, cleanup_list) {
+               ns_tree_remove(net);
                list_del_rcu(&net->list);
+       }
        /* Cache last net. After we unlock rtnl, no one new net
         * added to net_namespace_list can assign nsid pointer
         * to a net from net_kill_list (see peernet2id_alloc()).