[3/3] dm ioctl: add data secure (bufer wipe) flag

Commit Message

Milan Broz Feb. 3, 2011, 12:08 a.m. UTC

None

Patch

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 189c7ab..9284c38 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1518,9 +1518,16 @@  static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param)
 	if (copy_from_user(dmi, user, tmp.data_size))
 		goto fail;
 
+	/* Wipe the user buffer so we do not return it to userspace */
+	if ((tmp.flags & DM_SECURE_DATA_FLAG) &&
+	    clear_user(user, tmp.data_size))
+		goto fail;
+
 	*param = dmi;
 	return 0;
 fail:
+	if (tmp.flags & DM_SECURE_DATA_FLAG)
+		memset(dmi, 0, tmp.data_size);
 	vfree(dmi);
 	return -EFAULT;
 }
@@ -1621,6 +1628,9 @@  static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
 	if (!r && copy_to_user(user, param, param->data_size))
 		r = -EFAULT;
 out:
+	if (param->flags & DM_SECURE_DATA_FLAG)
+		memset(param, 0, param_size);
+
 	vfree(param);
 	return r;
 }
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 78bbf47..c314198 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -267,9 +267,9 @@  enum {
 #define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR	4
-#define DM_VERSION_MINOR	19
-#define DM_VERSION_PATCHLEVEL	1
-#define DM_VERSION_EXTRA	"-ioctl (2011-01-07)"
+#define DM_VERSION_MINOR	20
+#define DM_VERSION_PATCHLEVEL	0
+#define DM_VERSION_EXTRA	"-ioctl (2011-02-02)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */
@@ -328,4 +328,10 @@  enum {
  */
 #define DM_UUID_FLAG			(1 << 14) /* In */
 
+/*
+ * If set, all buffers are wiped after use. Used when sending
+ * or requesting sensitive data like crypt key.
+ */
+#define DM_SECURE_DATA_FLAG		(1 << 15) /* In */
+
 #endif				/* _LINUX_DM_IOCTL_H */