Re: [PATCH v3 2/7] fs/namei.c: Add missing umask strip in vfs_tmpfile

Christian Brauner
2022-04-15T14:17:52Z

On Fri, Apr 15, 2022 at 07:02:18PM +0800, Yang Xu wrote:
> If underflying filesystem doesn't enable own CONFIG_FS_POSIX_ACL, then
> posix_acl_create can't be called. So we will miss umask strip, ie
> use ext4 with noacl or disblae CONFIG_EXT4_FS_POSIX_ACL.

Hm, maybe:

"All creation paths except for O_TMPFILE handle umask in the vfs
directly if the filesystem doesn't support or enable POSIX ACLs. If the
filesystem does then umask handling is deferred until
posix_acl_create().
Because, O_TMPFILE misses umask handling in the vfs it will not honor
umask settings. Fix this by adding the missing umask handling."

>
> Reported-by: Christian Brauner (Microsoft) <brauner@kernel.org>
> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
> ---

Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>

> fs/namei.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index 3f1829b3ab5b..bbc7c950bbdc 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3521,6 +3521,8 @@ struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
> child = d_alloc(dentry, &slash_name);
> if (unlikely(!child))
> goto out_err;
> + if (!IS_POSIXACL(dir))
> + mode &= ~current_umask();
> error = dir->i_op->tmpfile(mnt_userns, dir, child, mode);
> if (error)
> goto out_err;
> --
> 2.27.0
>