Re: [PATCH v3 2/4] xfs: initialize inode security on tmpfile creation

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Wed, Apr 16, 2014 at 08:51:38AM -0400, Stephen Smalley wrote:
> Maybe I spoke too soon.  IIUC, I_LINKABLE doesn't necessarily
> distinguish tmpfiles from other files, as some tmpfiles may be linkable
> and others not.  But what we want is a way to identify all tmpfiles when
> security_inode_init_security() is called if we are going to label them
> independently of the provided dir.

Oh, right.  If O_EXCL is specified (another annoying overload of the
flag..) the tmpfile can't ever be linked back into the filesystem
and thus doesn't have I_LINKABLE set.

I guess the best way to fix this is using the magic qstr you suggested
before.  That means security_inode_init_security would need to be
called after d_tmpfile, which most filesystems don't do right now.