linux-kernel - Re: [PATCH 1/1] file capabilities: remove cap_task

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: <20080319212007.GA12217@sergelap.austin.ibm.com>
Date:	Wed, 19 Mar 2008 16:20:07 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Serge E. Hallyn" <serue@...ibm.com>, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, morgan@...nel.org,
	buraphalinuxserver@...il.com, lcapitulino@...driva.com.br,
	stable@...nel.org
Subject: Re: [PATCH 1/1] file capabilities: remove cap_task_kill() (-git)

Quoting Andrew Morton (akpm@...ux-foundation.org):
> On Wed, 19 Mar 2008 11:56:35 -0500
> "Serge E. Hallyn" <serue@...ibm.com> wrote:
> 
> > (resending once against -git.  I had sent against -stable in
> > http://lkml.org/lkml/2008/2/28/225.  Without this patch,
> > atd is broken at least on some distros.)
> 
> So this fix is needed in 2.6.24.x?

Yes it is.

> > The original justification for cap_task_kill() was as follows:
> > 
> > 	check_kill_permission() does appropriate uid equivalence checks.
> > 	However with file capabilities it becomes possible for an
> > 	unprivileged user to execute a file with file capabilities
> > 	resulting in a more privileged task with the same uid.
> > 
> > However now that cap_task_kill() always returns 0 (permission
> > granted) when p->uid==current->uid, the whole hook is worthless,
> > and only likely to create more subtle problems in the corner cases
> > where it might still be called but return -EPERM.  Those cases
> > are basically when uids are different but euid/suid is equivalent
> > as per the check in check_kill_permission().
> > 
> > One example of a still-broken application is 'at' for non-root users.
> 
> This 2.6.25-rc6 patch doesn't apply correctly to 2.6.24.  I can't find a
> *formal* copy of your 2.6.24 patch on stable@...nel.org, so perhaps a
> resend for -stable is in order.

Argh, yes, will do.  Thanks.

-serge
--
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/