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

From: "xuyang2018.jy@fujitsu.com" <xuyang2018.jy@fujitsu.com>
To: Christian Brauner <brauner@kernel.org>
Cc: "david@fromorbit.com" <david@fromorbit.com>,
	"djwong@kernel.org" <djwong@kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
	"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"jlayton@kernel.org" <jlayton@kernel.org>
Subject: Re: [PATCH v3 2/7] fs/namei.c: Add missing umask strip in vfs_tmpfile
Date: Mon, 18 Apr 2022 02:55:53 +0000	[thread overview]
Message-ID: <625CE183.4020704@fujitsu.com> (raw)
In-Reply-To: <20220415141741.q7i7wwcmuzo5dgav@wittgenstein>

on 2022/4/15 22:17, Christian Brauner wrote:
> 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."
OK, will do it on v4.

Best Regards
Yang Xu
>
>>
>> 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
>>