ovl: remove privs in ovl_fallocate()

[ 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>

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index b56e1f7a8c62b61948cb5af034f5f1fa88b8ba5e..28cb05ef018c79088b7136198683e84e1dbd701f 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -516,9 +516,16 @@ 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);
@@ -529,6 +536,9 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
 
        fdput(real);
 
+out_unlock:
+       inode_unlock(inode);
+
        return ret;
 }