2023-06-01 21:27:50

by Demi Marie Obenour

[permalink] [raw]
Subject: [PATCH 5/6] device-mapper: Refuse to create device named "control"

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 <[email protected]>
---
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 fd46b249f6f856c49752063fc49d720e95df0525..b12592bcb4b2b8513f5da6208fb545203534d7ff 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -767,7 +767,12 @@ 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;
}

--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab