From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [PATCH 00/10] Control Flow Enforcement - Part (3) Date: Sun, 17 Jun 2018 13:16:02 +1000 Message-ID: <2b77abb17dfaf58b7c23fac9d8603482e1887337.camel@gmail.com> References: <20180607143807.3611-1-yu-cheng.yu@intel.com> <1528815820.8271.16.camel@2b52.sc.intel.com> <814fc15e80908d8630ff665be690ccbe6e69be88.camel@gmail.com> <1528988176.13101.15.camel@2b52.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1528988176.13101.15.camel@2b52.sc.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Yu-cheng Yu Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H.J. Lu" , Vedvyas Shanbhogue , "Ravi V. Shankar" , Dave Hansen , Andy Lutomirski , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , Mike Kravetz List-Id: linux-arch.vger.kernel.org On Thu, 2018-06-14 at 07:56 -0700, Yu-cheng Yu wrote: > On Thu, 2018-06-14 at 11:07 +1000, Balbir Singh wrote: > > On Tue, 2018-06-12 at 08:03 -0700, Yu-cheng Yu wrote: > > > On Tue, 2018-06-12 at 20:56 +1000, Balbir Singh wrote: > > > > > > > > On 08/06/18 00:37, Yu-cheng Yu wrote: > > > > > This series introduces CET - Shadow stack > > > > > > > > > > At the high level, shadow stack is: > > > > > > > > > > Allocated from a task's address space with vm_flags VM_SHSTK; > > > > > Its PTEs must be read-only and dirty; > > > > > Fixed sized, but the default size can be changed by sys admin. > > > > > > > > > > For a forked child, the shadow stack is duplicated when the next > > > > > shadow stack access takes place. > > > > > > > > > > For a pthread child, a new shadow stack is allocated. > > > > > > > > > > The signal handler uses the same shadow stack as the main program. > > > > > > > > > > > > > Even with sigaltstack()? > > > > > > > > > > Yes. > > > > I am not convinced that it would work, as we switch stacks, oveflow might > > be an issue. I also forgot to bring up setcontext(2), I presume those > > will get new shadow stacks > > Do you mean signal stack/sigaltstack overflow or swapcontext in a signal > handler? > I meant any combination of that. If there is a user space threads implementation that uses sigaltstack for switching threads Balbir Singh. > Yu-cheng > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f68.google.com ([74.125.83.68]:42636 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756947AbeFQDQP (ORCPT ); Sat, 16 Jun 2018 23:16:15 -0400 Message-ID: <2b77abb17dfaf58b7c23fac9d8603482e1887337.camel@gmail.com> Subject: Re: [PATCH 00/10] Control Flow Enforcement - Part (3) From: Balbir Singh Date: Sun, 17 Jun 2018 13:16:02 +1000 In-Reply-To: <1528988176.13101.15.camel@2b52.sc.intel.com> References: <20180607143807.3611-1-yu-cheng.yu@intel.com> <1528815820.8271.16.camel@2b52.sc.intel.com> <814fc15e80908d8630ff665be690ccbe6e69be88.camel@gmail.com> <1528988176.13101.15.camel@2b52.sc.intel.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Yu-cheng Yu Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H.J. Lu" , Vedvyas Shanbhogue , "Ravi V. Shankar" , Dave Hansen , Andy Lutomirski , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , Mike Kravetz Message-ID: <20180617031602.iUytadkxzpkhqqVFMpNWN3INT7yyBr5O18QKdrxHY5g@z> On Thu, 2018-06-14 at 07:56 -0700, Yu-cheng Yu wrote: > On Thu, 2018-06-14 at 11:07 +1000, Balbir Singh wrote: > > On Tue, 2018-06-12 at 08:03 -0700, Yu-cheng Yu wrote: > > > On Tue, 2018-06-12 at 20:56 +1000, Balbir Singh wrote: > > > > > > > > On 08/06/18 00:37, Yu-cheng Yu wrote: > > > > > This series introduces CET - Shadow stack > > > > > > > > > > At the high level, shadow stack is: > > > > > > > > > > Allocated from a task's address space with vm_flags VM_SHSTK; > > > > > Its PTEs must be read-only and dirty; > > > > > Fixed sized, but the default size can be changed by sys admin. > > > > > > > > > > For a forked child, the shadow stack is duplicated when the next > > > > > shadow stack access takes place. > > > > > > > > > > For a pthread child, a new shadow stack is allocated. > > > > > > > > > > The signal handler uses the same shadow stack as the main program. > > > > > > > > > > > > > Even with sigaltstack()? > > > > > > > > > > Yes. > > > > I am not convinced that it would work, as we switch stacks, oveflow might > > be an issue. I also forgot to bring up setcontext(2), I presume those > > will get new shadow stacks > > Do you mean signal stack/sigaltstack overflow or swapcontext in a signal > handler? > I meant any combination of that. If there is a user space threads implementation that uses sigaltstack for switching threads Balbir Singh. > Yu-cheng >