LSM: LoadPin: provide enablement CONFIG

kees · James Morris · commit b937190c40de · 2016-05-17T20:10:30.000+10:00
Instead of being enabled by default when SECURITY_LOADPIN is selected,
provide an additional (default off) config to determine the boot time
behavior. As before, the "loadpin.enabled=0/1" kernel parameter remains
available.

Suggested-by: James Morris &lt;jmorris@namei.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: James Morris &lt;james.l.morris@oracle.com&gt;
diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig
@@ -3,8 +3,17 @@ config SECURITY_LOADPIN
 	depends on SECURITY && BLOCK
 	help
 	  Any files read through the kernel file reading interface
-	  (kernel modules, firmware, kexec images, security policy) will
-	  be pinned to the first filesystem used for loading. Any files
-	  that come from other filesystems will be rejected. This is best
-	  used on systems without an initrd that have a root filesystem
-	  backed by a read-only device such as dm-verity or a CDROM.
+	  (kernel modules, firmware, kexec images, security policy)
+	  can be pinned to the first filesystem used for loading. When
+	  enabled, any files that come from other filesystems will be
+	  rejected. This is best used on systems without an initrd that
+	  have a root filesystem backed by a read-only device such as
+	  dm-verity or a CDROM.
+
+config SECURITY_LOADPIN_ENABLED
+	bool "Enforce LoadPin at boot"
+	depends on SECURITY_LOADPIN
+	help
+	  If selected, LoadPin will enforce pinning at boot. If not
+	  selected, it can be enabled at boot with the kernel parameter
+	  "loadpin.enabled=1".
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
@@ -45,7 +45,7 @@ static void report_load(const char *origin, struct file *file, char *operation)
 	kfree(pathname);
 }
 
-static int enabled = 1;
+static int enabled = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENABLED);
 static struct super_block *pinned_root;
 static DEFINE_SPINLOCK(pinned_root_spinlock);
 

Original file line number	Diff line number	Diff line change
`@@ -45,7 +45,7 @@ static void report_load(const char origin, struct file file, char *operation)`
`45`	`45`	`kfree(pathname);`
`46`	`46`	`}`
`47`	`47`
`48`		`-static int enabled = 1;`
	`48`	`+static int enabled = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENABLED);`
`49`	`49`	`static struct super_block *pinned_root;`
`50`	`50`	`static DEFINE_SPINLOCK(pinned_root_spinlock);`
`51`	`51`