[PATCH v2 10/16] device-mapper: Refuse to create device named "control"

Demi Marie Obenour
2023-05-30T20:33:04Z

Typical userspace setups create a symlink under /dev/mapper with the
name of the device, but /dev/mapper/control is reserved for the control
device. Therefore, trying to create such a device is almost certain to
be a userspace bug.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
---
drivers/md/dm-ioctl.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 52aa5505d23b2f3d9c0faf6e8a91b74cd7845581..9ae00e3c1a72c19575814cf473774835b364320b 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -771,7 +771,12 @@ static int get_target_version(struct file *filp, struct dm_ioctl *param, size_t
static int check_name(const char *name)
{
if (strchr(name, '/')) {
- DMERR("invalid device name");
+ DMERR("device name cannot contain '/'");
+ return -EINVAL;
+ }
+
+ if (strcmp(name, DM_CONTROL_NODE) == 0) {
+ DMERR("device name cannot be \"%s\"", DM_CONTROL_NODE);
return -EINVAL;
}