linux-kernel - Re: [PATCH RFC/RFT v2 2/2] kernel: converge common shadow stack flow agnostic to arch

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]

Message-ID: <57adad09dfd4b360a0871247919ae295e978fbe5.camel@intel.com>
Date: Thu, 14 Nov 2024 23:33:55 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "broonie@...nel.org" <broonie@...nel.org>, "debug@...osinc.com"
	<debug@...osinc.com>
CC: "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"Liam.Howlett@...cle.com" <Liam.Howlett@...cle.com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"lorenzo.stoakes@...cle.com" <lorenzo.stoakes@...cle.com>, "hpa@...or.com"
	<hpa@...or.com>, "mingo@...hat.com" <mingo@...hat.com>, "tglx@...utronix.de"
	<tglx@...utronix.de>, "x86@...nel.org" <x86@...nel.org>, "vbabka@...e.cz"
	<vbabka@...e.cz>, "arnd@...db.de" <arnd@...db.de>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>, "bp@...en8.de"
	<bp@...en8.de>, "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH RFC/RFT v2 2/2] kernel: converge common shadow stack flow
 agnostic to arch

On Thu, 2024-11-14 at 15:30 -0800, Deepak Gupta wrote:
> On Fri, Nov 01, 2024 at 10:39:15PM +0000, Mark Brown wrote:
> > On Fri, Nov 01, 2024 at 09:50:27PM +0000, Edgecombe, Rick P wrote:
> > > On Wed, 2024-10-16 at 14:57 -0700, Deepak Gupta wrote:
> > 
> > > > - * The maximum distance INCSSP can move the SSP is 2040 bytes, before
> > > > - * it would read the memory. Therefore a single page gap will be enough
> > > > - * to prevent any operation from shifting the SSP to an adjacent stack,
> > > > - * since it would have to land in the gap at least once, causing a
> > > > - * fault.
> > 
> > > I want to take a deeper look at this series once I can apply and test it, but
> > > can we maybe make this comment more generic and keep it? I think it is similar
> > > reasoning for arm (?), is there anything situation like this for risc-v? Or
> > > rather, why does risc-v have the guard gaps?
> > 
> > Yes, for arm64 you can only move the pointer in single frames so a
> > single page is enough.
> 
> Yeah on risc-v as well guard gap is expected and single page is enough.
> 
> I removed this comment from here because of x86 specifics. I can make it
> generic, do you think it belongs here or the place where we define
> VM_SHADOW_STACK?

I think near VM_SHADOW_STACK actually, good idea. IIRC it got moved from
VM_SHADOW_STACK because it was too x86 specific. So if it's generic I think that
would fit.