linux-kernel - Re: [PATCH 0/2] ima: policy search speedup

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Date:	Tue, 11 Dec 2012 14:07:22 -0500
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Eric Paris <eparis@...isplace.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Kasatkin, Dmitry" <dmitry.kasatkin@...el.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	James Morris <jmorris@...ei.org>
Subject: Re: [PATCH 0/2] ima: policy search speedup

On Tue, 2012-12-11 at 13:09 -0500, Eric Paris wrote:
> On Tue, Dec 11, 2012 at 12:55 PM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> 
> > And your "pseudo-filesystems" argument is pretty stupid too, since WE
> > ALREADY HAVE A FLAG FOR THAT!
> >
> > Guess where it is? Oh, it's in the place I already mentioned makes
> > more sense. Look for S_PRIVATE in inode->i_flags, and IS_PRIVATE() in
> > users. It's what the other security models already use to avoid
> > bothering calling down to the security layers. The fact that the
> > integrity layer bypasses the normal security layer in
> > ima_file_check(), for example, is no excuse to then make up totally
> > new flags.
> 
> IS_PRIVATE() is not used by and darn well better not be used by, all
> psuedo filesystems like procfs which IMA may want to ignore.  LSMs
> like to do control on them.  I thought S_PRIVATE was really only used
> by the anon_inode and reiserfs's really crazy ass internal inodes.  I
> could always be wrong.

I was actually wondering about the MS_NOSEC flag.  It's currently being
used by fuse, gfs2, ocfs2 and tmpfs.  (Not sure about xfs.)  Can someone
explain what it is being used for?

thanks,

Mimi

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