[PATCH 5.4 112/320] debugfs: lockdown: Allow reading debugfs files that are not world readable

Greg Kroah-Hartman
2022-01-24T19:32:43Z

From: Michal Suchanek <msuchanek@suse.de>

[ Upstream commit 358fcf5ddbec4e6706405847d6a666f5933a6c25 ]

When the kernel is locked down the kernel allows reading only debugfs
files with mode 444. Mode 400 is also valid but is not allowed.

Make the 444 into a mask.

Fixes: 5496197f9b08 ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Link: https://lore.kernel.org/r/20220104170505.10248-1-msuchanek@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/debugfs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index a32c5c7dcfd89..da87615ad69a7 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -146,7 +146,7 @@ static int debugfs_locked_down(struct inode *inode,
struct file *filp,
const struct file_operations *real_fops)
{
- if ((inode->i_mode & 07777) == 0444 &&
+ if ((inode->i_mode & 07777 & ~0444) == 0 &&
!(filp->f_mode & FMODE_WRITE) &&
!real_fops->unlocked_ioctl &&
!real_fops->compat_ioctl &&
--
2.34.1