[PATCH] module: check vermagic match exactly when load modules

[Xie XiuQi]

Usually, checking kernel version will be ignore when loading
modules if CONFIG_MODVERSIONS option is enable. This could
potentially lead to a mismatch with the running kernel.

With this option, we prevent to load the modules which vermagic
is not match exactly with the running kernel.

It could be set to N by default.

Signed-off-by: Xie XiuQi <xiex...@huawei.com>
---
init/Kconfig | 11 +++++++++++
kernel/module.c | 2 ++
2 files changed, 13 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index c24b6f7..ce9c23e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1889,6 +1889,17 @@ config MODVERSIONS
make them incompatible with the kernel you are running. If
unsure, say N.

+config MODULE_VERMAGIC_FORCE
+ bool "Require vermagic match exactly"
+ default n
+ depends on MODVERSIONS
+ help
+ Usually, checking kernel version will be ignore when loading
+ modules if CONFIG_MODVERSIONS option is enable. This could
+ potentially lead to a mismatch with the running kernel.
+ With this option, we prevent to load the modules which vermagic
+ is not match exactly with the running kernel. If unsure, say N.
+
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
help
diff --git a/kernel/module.c b/kernel/module.c
index 8f051a1..cf350d5 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1350,10 +1350,12 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
static inline int same_magic(const char *amagic, const char *bmagic,
bool has_crcs)
{
+#ifndef CONFIG_MODULE_VERMAGIC_FORCE
if (has_crcs) {
amagic += strcspn(amagic, " ");
bmagic += strcspn(bmagic, " ");
}
+#endif
return strcmp(amagic, bmagic) == 0;
}
#else
--
1.8.3.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majo...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

[Rusty Russell]

Xie XiuQi <xiex...@huawei.com> writes:
> Usually, checking kernel version will be ignore when loading
> modules if CONFIG_MODVERSIONS option is enable. This could
> potentially lead to a mismatch with the running kernel.
>
> With this option, we prevent to load the modules which vermagic
> is not match exactly with the running kernel.
>
> It could be set to N by default.

Hi Xie!

I don't understand this patch. The purpose of
CONFIG_MODVERSIONS is so that you can combine modules from different
kernel versions. If you don't want to do that, I suggest not setting
CONFIG_MODVERSIONS.

Cheers,
Rusty.