From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [PATCH 00/10] Control Flow Enforcement - Part (3) Date: Thu, 14 Jun 2018 11:07:23 +1000 Message-ID: <814fc15e80908d8630ff665be690ccbe6e69be88.camel@gmail.com> References: <20180607143807.3611-1-yu-cheng.yu@intel.com> <1528815820.8271.16.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: <1528815820.8271.16.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 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 Balbir Singh. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:38790 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935513AbeFNBHg (ORCPT ); Wed, 13 Jun 2018 21:07:36 -0400 Message-ID: <814fc15e80908d8630ff665be690ccbe6e69be88.camel@gmail.com> Subject: Re: [PATCH 00/10] Control Flow Enforcement - Part (3) From: Balbir Singh Date: Thu, 14 Jun 2018 11:07:23 +1000 In-Reply-To: <1528815820.8271.16.camel@2b52.sc.intel.com> References: <20180607143807.3611-1-yu-cheng.yu@intel.com> <1528815820.8271.16.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: <20180614010723.N84UCInOe3k3CW7N7b4iIxQU0ZeJ-j7NUxZzynsyo1k@z> 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 Balbir Singh.