sunrpc: check that domain table is empty at module unload.

hulk inclusion
category: bugfix
bugzilla: NA
CVE: CVE-2020-12656

---------------------------

The domain table should be empty at module unload.  If it isn't there is
a bug somewhere.  So check and report.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206651Signed-off-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NWenan Mao <maowenan@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/sunrpc/sunrpc.h

@@ -56,4 +56,5 @@ int svc_send_common(struct socket *sock, struct xdr_buf *xdr,
 
 int rpc_clients_notifier_register(void);
 void rpc_clients_notifier_unregister(void);
+void auth_domain_cleanup(void);
 #endif /* _NET_SUNRPC_SUNRPC_H */

net/sunrpc/sunrpc_syms.c

@@ -22,6 +22,7 @@
 #include <linux/sunrpc/rpc_pipe_fs.h>
 #include <linux/sunrpc/xprtsock.h>
 
+#include "sunrpc.h"
 #include "netns.h"
 
 unsigned int sunrpc_net_id;
@@ -130,6 +131,7 @@ cleanup_sunrpc(void)
 	unregister_rpc_pipefs();
 	rpc_destroy_mempool();
 	unregister_pernet_subsys(&sunrpc_net_ops);
+	auth_domain_cleanup();
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	rpc_unregister_sysctl();
 #endif

net/sunrpc/svcauth.c

@@ -18,6 +18,10 @@
 #include <linux/err.h>
 #include <linux/hash.h>
 
+#include <trace/events/sunrpc.h>
+
+#include "sunrpc.h"
+
 #define RPCDBG_FACILITY	RPCDBG_AUTH
 
 
@@ -170,3 +174,26 @@ struct auth_domain *auth_domain_find(char *name)
 	return auth_domain_lookup(name, NULL);
 }
 EXPORT_SYMBOL_GPL(auth_domain_find);
+
+/**
+ * auth_domain_cleanup - check that the auth_domain table is empty
+ *
+ * On module unload the auth_domain_table must be empty.  To make it
+ * easier to catch bugs which don't clean up domains properly, we
+ * warn if anything remains in the table at cleanup time.
+ *
+ * Note that we cannot proactively remove the domains at this stage.
+ * The ->release() function might be in a module that has already been
+ * unloaded.
+ */
+
+void auth_domain_cleanup(void)
+{
+	int h;
+	struct auth_domain *hp;
+
+	for (h = 0; h < DN_HASHMAX; h++)
+		hlist_for_each_entry(hp, &auth_domain_table[h], hash)
+			pr_warn("svc: domain %s still present at module unload.\n",
+				hp->name);
+}