[PATCH 6.1 0105/1146] ovl: remove privs in ovl_fallocate()

Greg Kroah-Hartman
2022-12-28T15:12:18Z

From: Amir Goldstein <amir73il@gmail.com>

[ Upstream commit 23a8ce16419a3066829ad4a8b7032a75817af65b ]

Underlying fs doesn't remove privs because fallocate is called with
privileged mounter credentials.

This fixes some failure in fstests generic/683..687.

Fixes: aab8848cee5e ("ovl: add ovl_fallocate()")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/overlayfs/file.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 755a11c63596..d066be3b9226 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -517,9 +517,16 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
const struct cred *old_cred;
int ret;

+ inode_lock(inode);
+ /* Update mode */
+ ovl_copyattr(inode);
+ ret = file_remove_privs(file);
+ if (ret)
+ goto out_unlock;
+
ret = ovl_real_fdget(file, &real);
if (ret)
- return ret;
+ goto out_unlock;

old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_fallocate(real.file, mode, offset, len);
@@ -530,6 +537,9 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len

fdput(real);

+out_unlock:
+ inode_unlock(inode);
+
return ret;
}

--
2.35.1