From: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
Cc: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>,
Stephen Smalley <sds-+05T5uksL2qpZYMLLGbcSA@public.gmane.org>,
x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
Peter Zijlstra
<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org>,
Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Denys Vlasenko <dvlasenk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Brian Gerst <brgerst-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Ard Biesheuvel
<ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH v2] x86/mm: warn on W+x mappings
Date: Mon, 12 Oct 2015 16:17:54 +0200 [thread overview]
Message-ID: <20151012141754.GA6621@gmail.com> (raw)
In-Reply-To: <20151012125548.GE2579-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
* Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org> wrote:
> On Mon, 12 Oct, at 02:49:36PM, Ingo Molnar wrote:
> >
> >
> > So why not unmap them after bootup? Is there any reason to call into EFI code
> > while the system is up and running?
>
> That's where the runtime services code lives. So if you want things like EFI
> variables (used by the distro installer, among other things) you need to map the
> runtime regions.
So EFI variables could be queried during bootup and saved on the Linux side.
Calling into firmware after the kernel has booted up is fragile in general -
beyond W+X the security considerations.
Thanks,
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>,
Stephen Smalley <sds@tycho.nsa.gov>,
x86@kernel.org, linux-kernel@vger.kernel.org,
keescook@chromium.org, Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andy Lutomirski <luto@kernel.org>,
Denys Vlasenko <dvlasenk@redhat.com>,
Brian Gerst <brgerst@gmail.com>,
linux-efi@vger.kernel.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [PATCH v2] x86/mm: warn on W+x mappings
Date: Mon, 12 Oct 2015 16:17:54 +0200 [thread overview]
Message-ID: <20151012141754.GA6621@gmail.com> (raw)
In-Reply-To: <20151012125548.GE2579@codeblueprint.co.uk>
* Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Mon, 12 Oct, at 02:49:36PM, Ingo Molnar wrote:
> >
> >
> > So why not unmap them after bootup? Is there any reason to call into EFI code
> > while the system is up and running?
>
> That's where the runtime services code lives. So if you want things like EFI
> variables (used by the distro installer, among other things) you need to map the
> runtime regions.
So EFI variables could be queried during bootup and saved on the Linux side.
Calling into firmware after the kernel has booted up is fragile in general -
beyond W+X the security considerations.
Thanks,
Ingo
next prev parent reply other threads:[~2015-10-12 14:17 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-02 19:29 [PATCH v2] x86/mm: warn on W+x mappings Stephen Smalley
2015-10-02 20:44 ` Kees Cook
2015-10-03 11:27 ` Ingo Molnar
2015-10-05 19:13 ` Stephen Smalley
2015-10-06 7:32 ` Ingo Molnar
2015-10-06 15:37 ` Stephen Smalley
2015-10-12 11:36 ` Borislav Petkov
[not found] ` <20151012113605.GB7384-fF5Pk5pvG8Y@public.gmane.org>
2015-10-12 12:41 ` Matt Fleming
2015-10-12 12:41 ` Matt Fleming
2015-10-12 12:49 ` Ingo Molnar
[not found] ` <20151012124936.GA6260-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-10-12 12:55 ` Matt Fleming
2015-10-12 12:55 ` Matt Fleming
[not found] ` <20151012125548.GE2579-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-10-12 14:17 ` Ingo Molnar [this message]
2015-10-12 14:17 ` Ingo Molnar
[not found] ` <20151012141754.GA6621-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-10-12 14:49 ` Matt Fleming
2015-10-12 14:49 ` Matt Fleming
[not found] ` <20151012144928.GF2579-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-10-12 15:34 ` Ard Biesheuvel
2015-10-12 15:34 ` Ard Biesheuvel
[not found] ` <CAKv+Gu95NoB5cPqZMeBLn7i0JWDDPKX63FuiMVD94HpbGhKrhA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-10-12 15:50 ` Matt Fleming
2015-10-12 15:50 ` Matt Fleming
[not found] ` <20151012155028.GH2579-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-10-12 16:43 ` Ard Biesheuvel
2015-10-12 16:43 ` Ard Biesheuvel
2015-10-14 15:18 ` Ingo Molnar
2015-10-14 15:30 ` Andy Lutomirski
2015-10-14 15:35 ` Borislav Petkov
[not found] ` <20151014153522.GC8218-fF5Pk5pvG8Y@public.gmane.org>
2015-10-15 10:10 ` Matt Fleming
2015-10-15 10:10 ` Matt Fleming
[not found] ` <20151015101016.GB2975-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-10-15 10:33 ` Borislav Petkov
2015-10-15 10:33 ` Borislav Petkov
2015-10-16 1:45 ` Ricardo Neri
2015-10-16 1:45 ` Ricardo Neri
2015-10-14 21:02 ` Matt Fleming
2015-10-21 9:42 ` Ingo Molnar
[not found] ` <20151021094242.GA12155-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-10-21 12:49 ` Ingo Molnar
2015-10-21 12:49 ` Ingo Molnar
[not found] ` <20151021124924.GA19262-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-10-21 12:57 ` Ard Biesheuvel
2015-10-21 12:57 ` Ard Biesheuvel
2015-10-21 13:24 ` Borislav Petkov
[not found] ` <20151021132430.GD3575-fF5Pk5pvG8Y@public.gmane.org>
2015-10-21 13:28 ` Ard Biesheuvel
2015-10-21 13:28 ` Ard Biesheuvel
2015-10-21 14:36 ` Borislav Petkov
[not found] ` <20151021143651.GE3575-fF5Pk5pvG8Y@public.gmane.org>
2015-10-21 18:46 ` Andy Lutomirski
2015-10-21 18:46 ` Andy Lutomirski
[not found] ` <CALCETrWwHLnt6=MiyuQY48zEaOUMuFTg1oN3NDdEOxa6XYMgCw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-10-21 20:45 ` Matt Fleming
2015-10-21 20:45 ` Matt Fleming
[not found] ` <20151021204522.GB20338-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-10-21 20:49 ` Andy Lutomirski
2015-10-21 20:49 ` Andy Lutomirski
2015-10-21 20:38 ` Matt Fleming
2015-10-21 20:38 ` Matt Fleming
2015-10-12 14:56 ` Josh Triplett
2015-10-14 15:19 ` Ingo Molnar
2015-10-14 16:47 ` Josh Triplett
2015-10-21 9:43 ` Ingo Molnar
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