keys: Network namespace domain tag

Create key domain tags for network namespaces and make it possible to
automatically tag keys that are used by networked services (e.g. AF_RXRPC,
AFS, DNS) with the default network namespace if not set by the caller.

This allows keys with the same description but in different namespaces to
coexist within a keyring.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: netdev@vger.kernel.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: linux-afs@lists.infradead.org

1 files changed, 20 insertions, 0 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 711b161505ac..88e603b85ed2 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -38,9 +38,16 @@ EXPORT_SYMBOL_GPL(net_namespace_list);
 DECLARE_RWSEM(net_rwsem);
 EXPORT_SYMBOL_GPL(net_rwsem);
 
+#ifdef CONFIG_KEYS
+static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
+#endif
+
 struct net init_net = {
 	.count		= REFCOUNT_INIT(1),
 	.dev_base_head	= LIST_HEAD_INIT(init_net.dev_base_head),
+#ifdef CONFIG_KEYS
+	.key_domain	= &init_net_key_domain,
+#endif
 };
 EXPORT_SYMBOL(init_net);
 
@@ -386,10 +393,22 @@ static struct net *net_alloc(void)
 	if (!net)
 		goto out_free;
 
+#ifdef CONFIG_KEYS
+	net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
+	if (!net->key_domain)
+		goto out_free_2;
+	refcount_set(&net->key_domain->usage, 1);
+#endif
+
 	rcu_assign_pointer(net->gen, ng);
 out:
 	return net;
 
+#ifdef CONFIG_KEYS
+out_free_2:
+	kmem_cache_free(net_cachep, net);
+	net = NULL;
+#endif
 out_free:
 	kfree(ng);
 	goto out;
@@ -566,6 +585,7 @@ static void cleanup_net(struct work_struct *work)
 	list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
 		list_del_init(&net->exit_list);
 		dec_net_namespaces(net->ucounts);
+		key_remove_domain(net->key_domain);
 		put_user_ns(net->user_ns);
 		net_drop_ns(net);
 	}