mtd: phram,slram: Disable when the kernel is locked down

jira LE-2629
feature Additional SecureBoot patches for dynamic lockdown
commit 78c8af872660c31779951583b6f1ebf283d95985
commit-source https://salsa.debian.org/kernel-team/linux.git
commit-patch-path debian/patches/features/all/lockdown
commit-info Checkout the commit sha above and move to the directory
            listed above to find Debian patches matching this commits
            summary line.

These drivers allow mapping arbitrary memory ranges as MTD devices.
This should be disabled to preserve the kernel's integrity when it is
locked down.

* Add the HWPARAM flag to the module parameters
* When slram is built-in, it uses __setup() to read kernel parameters,
  so add an explicit check security_locked_down() check

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Matthew Garrett <mjg59@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Joern Engel <joern@lazybastard.org>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: bwhacks

drivers/mtd/devices/phram.c

@@ -364,7 +364,11 @@ static int phram_param_call(const char *val, const struct kernel_param *kp)
 #endif
 }
 
-module_param_call(phram, phram_param_call, NULL, NULL, 0200);
+static const struct kernel_param_ops phram_param_ops = {
+	.set = phram_param_call
+};
+__module_param_call(MODULE_PARAM_PREFIX, phram, &phram_param_ops, NULL,
+		    0200, -1, KERNEL_PARAM_FL_HWPARAM | hwparam_iomem);
 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
 
 #ifdef CONFIG_OF

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>
 
@@ -65,7 +66,7 @@ typedef struct slram_mtd_list {
 #ifdef MODULE
 static char *map[SLRAM_MAX_DEVICES_PARAMS];
 
-module_param_array(map, charp, NULL, 0);
+module_param_hw_array(map, charp, iomem, NULL, 0);
 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
 #else
 static char *map;
@@ -281,11 +282,17 @@ static int __init init_slram(void)
 #ifndef MODULE
 	char *devstart;
 	char *devlength;
+	int ret;
 
 	if (!map) {
 		E("slram: not enough parameters.\n");
 		return(-EINVAL);
 	}
+
+	ret = security_locked_down(LOCKDOWN_MODULE_PARAMETERS);
+	if (ret)
+		return ret;
+
 	while (map) {
 		devname = devstart = devlength = NULL;