From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756077Ab0LQUSH (ORCPT ); Fri, 17 Dec 2010 15:18:07 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:53606 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755218Ab0LQUSE (ORCPT ); Fri, 17 Dec 2010 15:18:04 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: "Serge E. Hallyn" Cc: LSM , James Morris , Kees Cook , containers@lists.linux-foundation.org, kernel list , Alexey Dobriyan , Michael Kerrisk References: <20101217152246.GA8221@mail.hallyn.com> <20101217152458.GA11162@mail.hallyn.com> <20101217152547.GB11162@mail.hallyn.com> <20101217152625.GC11162@mail.hallyn.com> <20101217152659.GD11162@mail.hallyn.com> <20101217200903.GA15528@mail.hallyn.com> Date: Fri, 17 Dec 2010 12:17:58 -0800 In-Reply-To: <20101217200903.GA15528@mail.hallyn.com> (Serge E. Hallyn's message of "Fri, 17 Dec 2010 20:09:03 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18kLBRqh7MflzGrr/TPxHTix9KYv9Eaa/U= X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 1.6 XMSubMetaSx_00 1+ Sexy Words * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;"Serge E. Hallyn" X-Spam-Relay-Country: Subject: Re: [RFC 4/5] user namespaces: allow killing tasks in your own or child userns X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Serge E. Hallyn" writes: > Quoting Eric W. Biederman (ebiederm@xmission.com): >> > --- a/kernel/signal.c >> > +++ b/kernel/signal.c >> > @@ -659,11 +686,7 @@ static int check_kill_permission(int sig, struct siginfo *info, >> > cred = current_cred(); >> > tcred = __task_cred(t); >> Nit pick you don't need to compute cred and tcred here now. > > Just to make sure I understand right: you mean wait until after the > same_thread_group() check to save calculation in that case, right? I mean cred and tcred are only use in kill_ok_by_cred. So we can eliminate those two variables from check_kill_permission. >> > if (!same_thread_group(current, t) && >> > - (cred->euid ^ tcred->suid) && >> > - (cred->euid ^ tcred->uid) && >> > - (cred->uid ^ tcred->suid) && >> > - (cred->uid ^ tcred->uid) && >> > - !capable(CAP_KILL)) { >> > + !kill_ok_by_cred(t)) { >> > switch (sig) { >> > case SIGCONT: >> > sid = task_session(t); Eric