linux-kernel - [PATCH 02/12] Enforce module signatures when trusted kernel is enabled

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Date:	Fri, 13 Mar 2015 11:38:18 -1000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	linux-security-module@...r.kernel.org
Cc:	james.l.morris@...cle.com, serge@...lyn.com,
	linux-kernel@...r.kernel.org, keescook@...omium.org, hpa@...or.com,
	gnomes@...rguk.ukuu.org.uk,
	Matthew Garrett <matthew.garrett@...ula.com>
Subject: [PATCH 02/12] Enforce module signatures when trusted kernel is enabled

If trusted_kernel is true, require that all modules have valid signatures.

Signed-off-by: Matthew Garrett <matthew.garrett@...ula.com>
---
 include/linux/module.h    | 6 ++++++
 kernel/module.c           | 6 ++++++
 security/trusted_kernel.c | 6 +++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 42999fe..1cf89e2 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -502,6 +502,8 @@ int unregister_module_notifier(struct notifier_block *nb);
 
 extern void print_modules(void);
 
+void enable_module_sig_enforce(void);
+
 #else /* !CONFIG_MODULES... */
 
 /* Given an address, look for it in the exception tables. */
@@ -612,6 +614,10 @@ static inline int unregister_module_notifier(struct notifier_block *nb)
 static inline void print_modules(void)
 {
 }
+
+static inline void enable_module_sig_enforce(void)
+{
+}
 #endif /* CONFIG_MODULES */
 
 #ifdef CONFIG_SYSFS
diff --git a/kernel/module.c b/kernel/module.c
index cc93cf6..842f58e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3893,3 +3893,9 @@ void module_layout(struct module *mod,
 }
 EXPORT_SYMBOL(module_layout);
 #endif
+
+void enable_module_sig_enforce(void)
+{
+	sig_enforce = true;
+}
+EXPORT_SYMBOL(enable_module_sig_enforce);
diff --git a/security/trusted_kernel.c b/security/trusted_kernel.c
index 2808113..22c4c30 100644
--- a/security/trusted_kernel.c
+++ b/security/trusted_kernel.c
@@ -11,6 +11,7 @@
 
 #include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/module.h>
 #include <linux/security.h>
 #include <linux/uaccess.h>
 
@@ -29,6 +30,9 @@ int set_trusted_kernel(bool new_trusted_kernel)
 
 	trusted_kernel = new_trusted_kernel;
 
+	if (trusted_kernel == true)
+		enable_module_sig_enforce();
+
 	return 0;
 }
 EXPORT_SYMBOL(set_trusted_kernel);
@@ -105,7 +109,7 @@ late_initcall(setup_trusted_kernel);
 
 static int __init enable_trusted_kernel(char *__str)
 {
-	trusted_kernel = true;
+	set_trusted_kernel(true);
 	return 1;
 }
 __setup("trusted_kernel", enable_trusted_kernel);
-- 
2.1.0

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