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

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Date:	Wed, 9 Dec 2015 21:34:04 +0800
From:	Xie XiuQi <xiexiuqi@...wei.com>
To:	<rusty@...tcorp.com.au>, <paulmck@...ux.vnet.ibm.com>,
	<akpm@...ux-foundation.org>, <bobby.prani@...il.com>
CC:	<dhowells@...hat.com>, <David.Woodhouse@...el.com>,
	<linux-kernel@...r.kernel.org>, <hannes@...xchg.org>,
	<iulia.manda21@...il.com>, <luto@...capital.net>,
	<huawei.libin@...wei.com>
Subject: [PATCH] module: check vermagic match exactly when load modules

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 <xiexiuqi@...wei.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

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