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From: Kees Cook <keescook@chromium.org>
To: Jann Horn <jannh@google.com>
Cc: YiFei Zhu <yifeifz2@illinois.edu>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Tycho Andersen <tycho@tycho.pizza>,
	Andy Lutomirski <luto@amacapital.net>,
	Will Drewry <wad@chromium.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Giuseppe Scrivano <gscrivan@redhat.com>,
	Tobin Feldman-Fitzthum <tobin@ibm.com>,
	Dimitrios Skarlatos <dskarlat@cs.cmu.edu>,
	Valentin Rothberg <vrothber@redhat.com>,
	Hubertus Franke <frankeh@us.ibm.com>,
	Jack Chen <jianyan2@illinois.edu>,
	Josep Torrellas <torrella@illinois.edu>,
	Tianyin Xu <tyxu@illinois.edu>, bpf <bpf@vger.kernel.org>,
	Linux Containers <containers@lists.linux-foundation.org>,
	Linux API <linux-api@vger.kernel.org>,
	kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/6] x86: Enable seccomp architecture tracking
Date: Thu, 24 Sep 2020 00:12:19 -0700	[thread overview]
Message-ID: <202009240011.A56710DC@keescook> (raw)
In-Reply-To: <CAG48ez1BXWdWA5zPzOD21bQ4RsHQ6bSDWR8soTkkNphJ=zdHWw@mail.gmail.com>

On Thu, Sep 24, 2020 at 02:45:45AM +0200, Jann Horn wrote:
> On Thu, Sep 24, 2020 at 1:29 AM Kees Cook <keescook@chromium.org> wrote:
> > Provide seccomp internals with the details to calculate which syscall
> > table the running kernel is expecting to deal with. This allows for
> > efficient architecture pinning and paves the way for constant-action
> > bitmaps.
> [...]
> > diff --git a/arch/x86/include/asm/seccomp.h b/arch/x86/include/asm/seccomp.h
> [...]
> > +#ifdef CONFIG_X86_64
> [...]
> > +#else /* !CONFIG_X86_64 */
> > +# define SECCOMP_ARCH                                  AUDIT_ARCH_I386
> > +#endif
> 
> If we are on a 32-bit kernel, performing architecture number checks in
> the kernel is completely pointless, because we know that there is only
> a single architecture identifier under which syscalls can happen.
> 
> While this patch is useful for enabling the bitmap logic in the
> following patches, I think it adds unnecessary overhead in the context
> of the previous patch.

That's what the RFC was trying to do (avoid the logic if there is only a
single arch known to the kernel). I will rework this a bit harder. :)

-- 
Kees Cook

  reply	other threads:[~2020-09-24  7:13 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23 23:29 [PATCH v1 0/6] seccomp: Implement constant action bitmaps Kees Cook
2020-09-23 23:29 ` [PATCH 1/6] seccomp: Introduce SECCOMP_PIN_ARCHITECTURE Kees Cook
2020-09-24  0:41   ` Jann Horn
2020-09-24  7:11     ` Kees Cook
2020-09-23 23:29 ` [PATCH 2/6] x86: Enable seccomp architecture tracking Kees Cook
2020-09-24  0:45   ` Jann Horn
2020-09-24  7:12     ` Kees Cook [this message]
2020-09-23 23:29 ` [PATCH 3/6] seccomp: Implement constant action bitmaps Kees Cook
2020-09-24  0:25   ` Jann Horn
2020-09-24  7:36     ` Kees Cook
2020-09-24  8:07       ` YiFei Zhu
2020-09-24  8:15         ` Kees Cook
2020-09-24  8:22           ` YiFei Zhu
2020-09-24 12:28       ` Jann Horn
2020-09-24 12:37         ` David Laight
2020-09-24 12:56           ` Jann Horn
     [not found]   ` <DM6PR11MB271492D0565E91475D949F5DEF390@DM6PR11MB2714.namprd11.prod.outlook.com>
2020-09-24  0:36     ` YiFei Zhu
2020-09-24  7:38       ` Kees Cook
2020-09-24  7:51         ` YiFei Zhu
2020-09-23 23:29 ` [PATCH 4/6] seccomp: Emulate basic filters for constant action results Kees Cook
2020-09-23 23:47   ` Jann Horn
2020-09-24  7:46     ` Kees Cook
2020-09-24 15:28       ` Paul Moore
2020-09-24 19:52         ` Kees Cook
2020-09-24 20:46           ` Paul Moore
2020-09-24 21:35             ` Kees Cook
2020-09-23 23:29 ` [PATCH 5/6] selftests/seccomp: Compare bitmap vs filter overhead Kees Cook
2020-09-23 23:29 ` [PATCH 6/6] [DEBUG] seccomp: Report bitmap coverage ranges Kees Cook
2020-09-24 13:40 ` [PATCH v1 0/6] seccomp: Implement constant action bitmaps Rasmus Villemoes
2020-09-24 13:58   ` YiFei Zhu
2020-09-25  5:56     ` Rasmus Villemoes
2020-09-25  7:07       ` YiFei Zhu
2020-09-26 18:11         ` YiFei Zhu
2020-09-28 20:04           ` Kees Cook
2020-09-28 20:16             ` YiFei Zhu
2020-09-24 14:05   ` Jann Horn
2020-09-24 18:57 ` Andrea Arcangeli
2020-09-24 19:18   ` Jann Horn
     [not found]   ` <9dbe8e3bbdad43a1872202ff38c34ca2@DM5PR11MB1692.namprd11.prod.outlook.com>
2020-09-24 19:48     ` Tianyin Xu
2020-09-24 20:00   ` Kees Cook

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