module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS

If MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS is enabled (default=n), the
requirement for modules to import all namespaces that are used by
the module is relaxed.

Enabling this option effectively allows (invalid) modules to be loaded
while only a warning is emitted.

Disabling this option keeps the enforcement at module loading time and
loading is denied if the module's imports are not satisfactory.

Reviewed-by: Martijn Coenen <maco@android.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 6bb9b938f9c7..f76efcf2043e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1408,9 +1408,16 @@ static int verify_namespace_is_imported(const struct load_info *info,
                         imported_namespace = get_next_modinfo(
                                 info, "import_ns", imported_namespace);
                 }
-                pr_err("%s: module uses symbol (%s) from namespace %s, but does not import it.\n",
-                       mod->name, kernel_symbol_name(sym), namespace);
+#ifdef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
+                pr_warn(
+#else
+                pr_err(
+#endif
+                        "%s: module uses symbol (%s) from namespace %s, but does not import it.\n",
+                        mod->name, kernel_symbol_name(sym), namespace);
+#ifndef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
                 return -EINVAL;
+#endif
         }
         return 0;
 }