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Date:   Fri, 15 Apr 2022 16:17:41 +0200
From:   Christian Brauner <brauner@kernel.org>
To:     Yang Xu <xuyang2018.jy@fujitsu.com>
Cc:     david@fromorbit.com, djwong@kernel.org,
        linux-fsdevel@vger.kernel.org, ceph-devel@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org,
        viro@zeniv.linux.org.uk, jlayton@kernel.org
Subject: Re: [PATCH v3 2/7] fs/namei.c: Add missing umask strip in vfs_tmpfile
Message-ID: <20220415141741.q7i7wwcmuzo5dgav@wittgenstein>
References: <1650020543-24908-1-git-send-email-xuyang2018.jy@fujitsu.com>
 <1650020543-24908-2-git-send-email-xuyang2018.jy@fujitsu.com>
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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
>