[d-kernel] [PATCH v2 1/6] mtd: slram: Add the kernel lock down check

[Egor Ignatov <egori@altlinux.org>]

The slram MTD driver may map any memory pages no matter whether it's
reserved or whatever used for systems, which basically allows user
bypassing the lock down.

Add the check and abort the probe if the kernel is locked down for
LOCKDOWN_DEV_MEM.

Based on commit b3c782868ece ("mtd: phram: Add the kernel lock down check")

Suggested-by: Vitaly Chikunov <vt@altlinux.org>
Signed-off-by: Egor Ignatov <egori@altlinux.org>
---
 drivers/mtd/devices/slram.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/mtd/devices/slram.c b/drivers/mtd/devices/slram.c
index 69cb63d99f..2928d12343 100644
--- a/drivers/mtd/devices/slram.c
+++ b/drivers/mtd/devices/slram.c
@@ -43,6 +43,7 @@
 #include <linux/ioctl.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/security.h>
 
 #include <linux/mtd/mtd.h>
 
@@ -277,6 +278,11 @@ __setup("slram=", mtd_slram_setup);
 static int __init init_slram(void)
 {
 	char *devname;
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_DEV_MEM);
+	if (ret)
+		return ret;
 
 #ifndef MODULE
 	char *devstart;
-- 
2.50.1