linux-kernel - [PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190906103235.197072-6-maennich@google.com>
Date:   Fri,  6 Sep 2019 11:32:29 +0100
From:   Matthias Maennich <maennich@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, maennich@...gle.com, arnd@...db.de,
        gregkh@...uxfoundation.org, jeyu@...nel.org,
        joel@...lfernandes.org, lucas.de.marchi@...il.com,
        maco@...roid.com, sspatil@...gle.com, will@...nel.org,
        yamada.masahiro@...ionext.com, linux-kbuild@...r.kernel.org,
        linux-modules@...r.kernel.org, linux-usb@...r.kernel.org,
        usb-storage@...ts.one-eyed-alien.net
Subject: [PATCH v5 05/11] 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@...roid.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@...gle.com>
---
 init/Kconfig    | 13 +++++++++++++
 kernel/module.c | 11 +++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index bd7d650d4a99..cc28561288a7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2119,6 +2119,19 @@ config MODULE_COMPRESS_XZ
 
 endchoice
 
+config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
+	bool "Allow loading of modules with missing namespace imports"
+	help
+	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
+	  a namespace. A module that makes use of a symbol exported with such a
+	  namespace is required to import the namespace via MODULE_IMPORT_NS().
+	  There is no technical reason to enforce correct namespace imports,
+	  but it creates consistency between symbols defining namespaces and
+	  users importing namespaces they make use of. This option relaxes this
+	  requirement and lifts the enforcement when loading a module.
+
+	  If unsure, say N.
+
 config TRIM_UNUSED_KSYMS
 	bool "Trim unused exported kernel symbols"
 	depends on MODULES && !UNUSED_SYMBOLS
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;
 }
-- 
2.23.0.187.g17f5b7556c-goog