linux-ext4 - Re: [PATCH v2 1/2] xfs: fix tmpfile/selinux deadlock and initialize security/acl

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Message-ID: <20140418163920.GB13808@infradead.org>
Date:	Fri, 18 Apr 2014 09:39:20 -0700
From:	Christoph Hellwig <hch@...radead.org>
To:	Andreas Gruenbacher <andreas.gruenbacher@...bit.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Brian Foster <bfoster@...hat.com>, linux-man@...r.kernel.org,
	xfs@....sgi.com, linux-security-module@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH v2 1/2] xfs: fix tmpfile/selinux deadlock and initialize
 security/acl

On Wed, Apr 16, 2014 at 07:29:29PM +0200, Andreas Gruenbacher wrote:
> > Btw, I think the man page is wrong - given that the tmpfile is not
> > visible in the namespace it is obviously not created in the directory.
> > The directory passed in is just a handle for the filesystem it should be
> > created in.
> 
> I don't agree.  If the file is created with O_TMPFILE | O_EXCL, it is clear
> that the file will never be linked into the namespace.  Even then, there are
> operations which are affected by the inode permissions and label of the
> anonymous file, and those should still behave reasonably.  In this context,
> I would expect them to behave as if the file was actually created in the
> specified directory, not in the file system root or "nowhere" with no clearly
> defined permissions and security label.

So you want to define the files as being in a directory, but not
actually visible?  That's defintively a new and strange state to be in.

> > Inheriting any ACL on creating an anonymous file seems utterly wrong.
> 
> Why?

Because it has no parent to inherit it from.

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