linux-kernel - Re: [PATCH v2 23/39] x86: Introduce userspace API for CET enabling

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: <Yz8jdMgv6jEm9rcH@kernel.org>
Date:   Thu, 6 Oct 2022 21:50:28 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc:     "keescook@...omium.org" <keescook@...omium.org>,
        "bsingharora@...il.com" <bsingharora@...il.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Syromiatnikov, Eugene" <esyr@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Eranian, Stephane" <eranian@...gle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "fweimer@...hat.com" <fweimer@...hat.com>,
        "nadav.amit@...il.com" <nadav.amit@...il.com>,
        "jannh@...gle.com" <jannh@...gle.com>,
        "dethoma@...rosoft.com" <dethoma@...rosoft.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "kcc@...gle.com" <kcc@...gle.com>, "bp@...en8.de" <bp@...en8.de>,
        "oleg@...hat.com" <oleg@...hat.com>,
        "hjl.tools@...il.com" <hjl.tools@...il.com>,
        "Yang, Weijiang" <weijiang.yang@...el.com>,
        "Lutomirski, Andy" <luto@...nel.org>,
        "pavel@....cz" <pavel@....cz>, "arnd@...db.de" <arnd@...db.de>,
        "Moreira, Joao" <joao.moreira@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "jamorris@...ux.microsoft.com" <jamorris@...ux.microsoft.com>,
        "john.allen@....com" <john.allen@....com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "corbet@....net" <corbet@....net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "gorcunov@...il.com" <gorcunov@...il.com>
Subject: Re: [PATCH v2 23/39] x86: Introduce userspace API for CET enabling

On Mon, Oct 03, 2022 at 10:51:02PM +0000, Edgecombe, Rick P wrote:
> CC Mike about ptrace/CRIU question.
> 
> On Mon, 2022-10-03 at 12:01 -0700, Kees Cook wrote:
> > On Thu, Sep 29, 2022 at 03:29:20PM -0700, Rick Edgecombe wrote:
> > > From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> > > 
> > > Add three new arch_prctl() handles:
> > > 
> > >  - ARCH_CET_ENABLE/DISABLE enables or disables the specified
> > >    feature. Returns 0 on success or an error.
> > > 
> > >  - ARCH_CET_LOCK prevents future disabling or enabling of the
> > >    specified feature. Returns 0 on success or an error
> > > 
> > > The features are handled per-thread and inherited over
> > > fork(2)/clone(2),
> > > but reset on exec().

...

> > > +#include <linux/sched.h>
> > > +#include <linux/bitops.h>
> > > +#include <asm/prctl.h>
> > > +
> > > +long cet_prctl(struct task_struct *task, int option, unsigned long
> > > features)
> > > +{
> > > +	if (option == ARCH_CET_LOCK) {
> > > +		task->thread.features_locked |= features;
> > > +		return 0;
> > > +	}
> > > +
> > > +	/* Don't allow via ptrace */
> > > +	if (task != current)
> > > +		return -EINVAL;
> > 
> > ... but locking _is_ allowed via ptrace? If that intended, it should
> > be
> > explicitly mentioned in the commit log and in a comment here.
> 
> I believe CRIU needs to lock via ptrace as well. Maybe Mike can
> confirm.

Actually, I didn't use ptrace for locking, I did it with "plain"
arch_prctl().

I still can't say for sure CRIU won't need this, I didn't have time yet to
have a closer look at this set.
 
-- 
Sincerely yours,
Mike.