linux-kernel - Re: [PATCH 4/7] allow killing tasks in your own or child userns

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]

Date:	Tue, 11 Jan 2011 01:31:52 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Bastian Blank <bastian@...di.eu.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	containers@...ts.linux-foundation.org,
	kernel list <linux-kernel@...r.kernel.org>,
	LSM <linux-security-module@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Kees Cook <kees.cook@...onical.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [PATCH 4/7] allow killing tasks in your own or child userns

Quoting Bastian Blank (bastian@...di.eu.org):
> On Mon, Jan 10, 2011 at 04:51:51PM -0600, Serge Hallyn wrote:
> > Quoting Bastian Blank (bastian@...di.eu.org):
> > > Isn't that equal to this?
> > > 
> > > 	if (ns_capable(tcred->user->user_ns, CAP_KILL))
> > > 		return 1;
> > > 
> > > 	if (cred->user->user_ns == tcred->user->user_ns &&
> > > 	    (cred->euid == tcred->suid ||
> > > 	     cred->euid == tcred->uid ||
> > > 	     cred->uid == tcred->suid ||
> > > 	     cred->uid == tcred->uid))
> > > 		return 1;
> > > 
> > > 	return 0;
> > > 
> > > I would consider this much easier to read.
> > 
> > Unfortunately, it's actually not equivalent.  when capable()
> > returns success, then it sets the current->flags |= PF_SUPERPRIV.
> > If permission is granted based on userids and the capability
> > isn't needed, then we don't want to needlessly set PF_SUPERPRIV.
> 
> Well, then switch the two if-clauses.

hup, will do, much nicer, thanks.

> What is this flag used for anyway? I only see it used in the accounting
> stuff, and if every user can get it, it is not longer useful.

hm, I'm not sure...  maybe noone is using it!
--
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/