uuid: implement random uuid/guid

Link: https://lore.barebox.org/20240219083140.2713047-6-s.hauer@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 30 insertions, 0 deletions

diff --git a/lib/uuid.c b/lib/uuid.c
index db75be1725..60a651e330 100644
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -8,9 +8,39 @@
 
 #include <linux/uuid.h>
 #include <module.h>
+#include <stdlib.h>
 #include <linux/export.h>
 
 const guid_t guid_null;
 EXPORT_SYMBOL(guid_null);
 const uuid_t uuid_null;
 EXPORT_SYMBOL(uuid_null);
+
+/**
+ * generate_random_uuid - generate a random UUID
+ * @uuid: where to put the generated UUID
+ *
+ * Random UUID interface
+ *
+ * Used to create a Boot ID or a filesystem UUID/GUID, but can be
+ * useful for other kernel drivers.
+ */
+void generate_random_uuid(unsigned char uuid[16])
+{
+	get_random_bytes(uuid, 16);
+	/* Set UUID version to 4 --- truly random generation */
+	uuid[6] = (uuid[6] & 0x0F) | 0x40;
+	/* Set the UUID variant to DCE */
+	uuid[8] = (uuid[8] & 0x3F) | 0x80;
+}
+EXPORT_SYMBOL(generate_random_uuid);
+
+void generate_random_guid(unsigned char guid[16])
+{
+	get_random_bytes(guid, 16);
+	/* Set GUID version to 4 --- truly random generation */
+	guid[7] = (guid[7] & 0x0F) | 0x40;
+	/* Set the GUID variant to DCE */
+	guid[8] = (guid[8] & 0x3F) | 0x80;
+}
+EXPORT_SYMBOL(generate_random_guid);