linux-kernel - Re: [PATCH v29 25/32] x86/cet/shstk: Handle thread shadow stack

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Message-ID: <CAMe9rOoo5wC7AWbo3WO_GWvT5CXV3r3ysZ2qB8ZPi=giRBDetg@mail.gmail.com>
Date:   Thu, 26 Aug 2021 10:22:29 -0700
From:   "H.J. Lu" <hjl.tools@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Yu-cheng Yu <yu-cheng.yu@...el.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...nel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Dave Martin <Dave.Martin@....com>,
        Weijiang Yang <weijiang.yang@...el.com>,
        Pengfei Xu <pengfei.xu@...el.com>,
        Haitao Huang <haitao.huang@...el.com>,
        Rick P Edgecombe <rick.p.edgecombe@...el.com>
Subject: Re: [PATCH v29 25/32] x86/cet/shstk: Handle thread shadow stack

On Thu, Aug 26, 2021 at 9:49 AM Borislav Petkov <bp@...en8.de> wrote:
>
> On Fri, Aug 20, 2021 at 11:11:54AM -0700, Yu-cheng Yu wrote:
> > diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
> > index 5993aa8db338..7c1ca2476a5e 100644
> > --- a/arch/x86/kernel/shstk.c
> > +++ b/arch/x86/kernel/shstk.c
> > @@ -75,6 +75,61 @@ int shstk_setup(void)
> >       return err;
> >  }
> >
> > +int shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long clone_flags,
> > +                          unsigned long stack_size)
> > +{
> > +     struct thread_shstk *shstk = &tsk->thread.shstk;
> > +     struct cet_user_state *state;
> > +     unsigned long addr;
> > +
> > +     if (!shstk->size)
> > +             return 0;
> > +
> > +     /*
> > +      * Earlier clone() does not pass stack_size.  Use RLIMIT_STACK and
>
> What is "earlier clone()"?

clone() doesn't have stack size info which was added to clone3().

> > +      * cap to 4 GB.
> > +      */
>
> --
> Regards/Gruss,
>     Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette



-- 
H.J.