[PATCH v2 11/16] device-mapper: "." and ".." are not valid symlink names

Demi Marie Obenour
2023-05-30T20:33:16Z

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>
---
drivers/md/dm-ioctl.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 9ae00e3c1a72c19575814cf473774835b364320b..17ece816d490b6c40d019da131ade44c9a201dab 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -775,8 +775,10 @@ 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;
}