torvalds/linux
torvalds/linux
2
0
Fork 0
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-09-04 20:19:47 +08:00
Code

s390/hypfs: Enable limited access during lockdown

Browse Source 
When kernel lockdown is active, debugfs_locked_down() blocks access to
hypfs files that register ioctl callbacks, even if the ioctl interface
is not required for a function. This unnecessarily breaks userspace
tools that only rely on read operations.

Resolve this by registering a minimal set of file operations during
lockdown, avoiding ioctl registration and preserving access for affected
tooling.

Note that this change restores hypfs functionality when lockdown is
active from early boot (e.g. via lockdown=integrity kernel parameter),
but does not apply to scenarios where lockdown is enabled dynamically
while Linux is running.

Tested-by: Mete Durlu <meted@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Fixes: 5496197f9b ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Peter Oberparleiter 2025-08-21 15:12:37 +02:00 committed by Alexander Gordeev
parent fec7bdfe7f
commit 3868f91044
1 changed files with 2 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/s390/hypfs/hypfs_dbfs.c
View File

@ -6,6 +6,7 @@
* Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com> * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
*/ */
#include <linux/security.h>
#include <linux/slab.h> #include <linux/slab.h>
#include "hypfs.h" #include "hypfs.h"
@ -84,7 +85,7 @@ void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
{ {
const struct file_operations *fops = &dbfs_ops; const struct file_operations *fops = &dbfs_ops;
if (df->unlocked_ioctl) if (df->unlocked_ioctl && !security_locked_down(LOCKDOWN_DEBUGFS))
fops = &dbfs_ops_ioctl; fops = &dbfs_ops_ioctl;
df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, fops); df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, fops);
mutex_init(&df->lock); mutex_init(&df->lock);