Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755155AbaFXTwI (ORCPT ); Tue, 24 Jun 2014 15:52:08 -0400 Received: from mail-lb0-f171.google.com ([209.85.217.171]:63537 "EHLO mail-lb0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754426AbaFXTwG (ORCPT ); Tue, 24 Jun 2014 15:52:06 -0400 MIME-Version: 1.0 In-Reply-To: References: <1403560693-21809-1-git-send-email-keescook@chromium.org> <1403560693-21809-5-git-send-email-keescook@chromium.org> <20140624191815.GA3623@redhat.com> <20140624193055.GA4482@redhat.com> From: Andy Lutomirski Date: Tue, 24 Jun 2014 12:51:43 -0700 Message-ID: Subject: Re: [PATCH v7 4/9] seccomp: move no_new_privs into seccomp To: Kees Cook Cc: Oleg Nesterov , "linux-kernel@vger.kernel.org" , Alexei Starovoitov , "Michael Kerrisk (man-pages)" , Andrew Morton , Daniel Borkmann , Will Drewry , Julien Tinnes , David Drysdale , Linux API , X86 ML , "linux-arm-kernel@lists.infradead.org" , linux-mips@linux-mips.org, linux-arch , LSM List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 24, 2014 at 12:50 PM, Kees Cook wrote: > On Tue, Jun 24, 2014 at 12:34 PM, Andy Lutomirski wrote: >> On Tue, Jun 24, 2014 at 12:30 PM, Oleg Nesterov wrote: >>> On 06/24, Andy Lutomirski wrote: >>>> >>>> On Tue, Jun 24, 2014 at 12:18 PM, Oleg Nesterov wrote: >>>> >> >>>> >> -struct seccomp { }; >>>> >> +struct seccomp { >>>> >> + unsigned long flags; >>>> >> +}; >>>> > >>>> > A bit messy ;) >>>> > >>>> > I am wondering if we can simply do >>>> > >>>> > static inline bool current_no_new_privs(void) >>>> > { >>>> > if (current->no_new_privs) >>>> > return true; >>>> > >>>> > #ifdef CONFIG_SECCOMP >>>> > if (test_thread_flag(TIF_SECCOMP)) >>>> > return true; >>>> > #endif >>>> >>>> Nope -- privileged users can enable seccomp w/o nnp. >>> >>> Indeed, I am stupid. >>> >>> Still it would be nice to cleanup this somehow. The new member is only >>> used as a previous ->no_new_privs, just it is long to allow the concurent >>> set/get. Logically it doesn't even belong to seccomp{}. >> >> We could add an unsigned long atomic flags field to task_struct. > > I thought that had gotten shot down originally, but given the current > state of the patch series, it would be effectively identical, since my > earlier attempt at keeping sizes the same (with alternate accessors) > was too messy. I will change this as well. > >> Grr. Why isn't there an unsigned *int* atomic bitmask type? Even u64 >> would be better. unsigned long is useless. > > Useless beyond 32 bits. ;) It basically guarantees 32 wasted bits on 64-bit systems. I guess that unsigned long foo[64/BITS_PER_LONG] would work, bit that's hideous. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/