linux-kernel - Re: Security issues with local filesystem caching

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1162496968.6071.38.camel@lade.trondhjem.org>
Date:	Thu, 02 Nov 2006 14:49:27 -0500
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	David Howells <dhowells@...hat.com>
Cc:	Stephen Smalley <sds@...ho.nsa.gov>,
	Karl MacMillan <kmacmill@...hat.com>, jmorris@...ei.org,
	chrisw@...s-sol.org, selinux@...ho.nsa.gov,
	linux-kernel@...r.kernel.org, aviro@...hat.com
Subject: Re: Security issues with local filesystem caching

On Thu, 2006-11-02 at 17:16 +0000, David Howells wrote:
> Stephen Smalley <sds@...ho.nsa.gov> wrote:
> 
> > Unless there is some benefit to setting a ->fssid and checking against
> > it (e.g. safeguarding the module against unintentional internal access),
> > I think the task flag approach is preferable.
> 
> Well, I think the use of ->fssid is simpler and faster from an implementation
> standpoint (see the attached patch), and it can always be used for such as the
> in-kernel nfsd later.
> 
> The way I've done it in this patch is to have ->fssid shadow ->sid as long as
> they're the same.  But ->fssid can be set to something else and then later
> reset, at which point it becomes the same as ->sid again.  A hook is provided
> to perform both of these operations:
> 
> 	security_set_fssid(overriding_SID);  //set
> 	...
> 	security_set_fssid(SECSID_NULL);  //reset
> 
> The rest of the patch is that more or less anywhere ->sid is used to represent
> a process as an actor, this is replaced with ->fssid.  This part requires no
> conditional jumps.  It becomes a bit tricky around execve() time, but I think
> it's reasonable to ignore that as execve() is unlikely to happen in an
> overridden context; or maybe the execve() related ops should be failed if
> ->sid != ->fssid.
> 
> Do you think this is reasonable?  Or do you definitely want me to use the
> suppression flag approach instead?

Just why are you doing all this? Why do we need a back-end that requires
all this extra client-side security infrastructure in order to work? 

IOW: What is wrong with the existing CacheFS?

Trond

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/