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Subject[PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
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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>
---
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
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