1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/md/dm-verity-loadpin.c b/drivers/md/dm-verity-loadpin.c
new file mode 100644
index 000000000000..10c18bc1652c
--- /dev/null
+++ b/drivers/md/dm-verity-loadpin.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/dm-verity-loadpin.h>
+
+#include "dm.h"
+#include "dm-verity.h"
+
+#define DM_MSG_PREFIX	"verity-loadpin"
+
+LIST_HEAD(dm_verity_loadpin_trusted_root_digests);
+
+static bool is_trusted_verity_target(struct dm_target *ti)
+{
+	u8 *root_digest;
+	unsigned int digest_size;
+	struct dm_verity_loadpin_trusted_root_digest *trd;
+	bool trusted = false;
+
+	if (!dm_is_verity_target(ti))
+		return false;
+
+	if (dm_verity_get_root_digest(ti, &root_digest, &digest_size))
+		return false;
+
+	list_for_each_entry(trd, &dm_verity_loadpin_trusted_root_digests, node) {
+		if ((trd->len == digest_size) &&
+		    !memcmp(trd->data, root_digest, digest_size)) {
+			trusted = true;
+			break;
+		}
+	}
+
+	kfree(root_digest);
+
+	return trusted;
+}
+
+/*
+ * Determines whether the file system of a superblock is located on
+ * a verity device that is trusted by LoadPin.
+ */
+bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev)
+{
+	struct mapped_device *md;
+	struct dm_table *table;
+	struct dm_target *ti;
+	int srcu_idx;
+	bool trusted = false;
+
+	if (list_empty(&dm_verity_loadpin_trusted_root_digests))
+		return false;
+
+	md = dm_get_md(bdev->bd_dev);
+	if (!md)
+		return false;
+
+	table = dm_get_live_table(md, &srcu_idx);
+
+	if (dm_table_get_num_targets(table) != 1)
+		goto out;
+
+	ti = dm_table_get_target(table, 0);
+
+	if (is_trusted_verity_target(ti))
+		trusted = true;
+
+out:
+	dm_put_live_table(md, srcu_idx);
+	dm_put(md);
+
+	return trusted;
+}