dm ioctl: Refuse to create device named "." or ".."

Using either of these is going to greatly confuse userspace, as they are
not valid symlink names and so creating the usual /dev/mapper/NAME
symlink will not be possible.  As creating a device with either of these
names is almost certainly a userspace bug, just error out.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index e172a91..16244a7 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -771,8 +771,10 @@ static int check_name(const char *name)
                return -EINVAL;
        }
 
-       if (strcmp(name, DM_CONTROL_NODE) == 0) {
-               DMERR("device name cannot be \"%s\"", DM_CONTROL_NODE);
+       if (strcmp(name, DM_CONTROL_NODE) == 0 ||
+           strcmp(name, ".") == 0 ||
+           strcmp(name, "..") == 0) {
+               DMERR("device name cannot be \"%s\", \".\", or \"..\"", DM_CONTROL_NODE);
                return -EINVAL;
        }