From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Kees Cook <keescook@chromium.org>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>,
containers@lists.linux-foundation.org,
YiFei Zhu <yifeifz2@illinois.edu>, bpf <bpf@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Aleksa Sarai <cyphar@cyphar.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andy Lutomirski <luto@amacapital.net>,
Dimitrios Skarlatos <dskarlat@cs.cmu.edu>,
Giuseppe Scrivano <gscrivan@redhat.com>,
Hubertus Franke <frankeh@us.ibm.com>,
Jack Chen <jianyan2@illinois.edu>, Jann Horn <jannh@google.com>,
Josep Torrellas <torrella@illinois.edu>,
Tianyin Xu <tyxu@illinois.edu>,
Tobin Feldman-Fitzthum <tobin@ibm.com>,
Tycho Andersen <tycho@tycho.pizza>,
Valentin Rothberg <vrothber@redhat.com>,
Will Drewry <wad@chromium.org>
Subject: Re: [PATCH v2 seccomp 1/6] seccomp: Move config option SECCOMP to arch/Kconfig
Date: Wed, 28 Oct 2020 09:18:51 +0100 [thread overview]
Message-ID: <CAMuHMdX-y+ButCt=CH+Ao=RtO_eGz0DaTJupwuHNa7=Xi_AGoQ@mail.gmail.com> (raw)
In-Reply-To: <202010271653.B6D7D6B@keescook>
Hi Kees,
On Wed, Oct 28, 2020 at 1:06 AM Kees Cook <keescook@chromium.org> wrote:
> On Tue, Oct 27, 2020 at 10:52:39AM +0100, Geert Uytterhoeven wrote:
> > On Thu, Sep 24, 2020 at 2:48 PM YiFei Zhu <zhuyifei1999@gmail.com> wrote:
> > > From: YiFei Zhu <yifeifz2@illinois.edu>
> > >
> > > In order to make adding configurable features into seccomp
> > > easier, it's better to have the options at one single location,
> > > considering easpecially that the bulk of seccomp code is
> > > arch-independent. An quick look also show that many SECCOMP
> > > descriptions are outdated; they talk about /proc rather than
> > > prctl.
> > >
> > > As a result of moving the config option and keeping it default
> > > on, architectures arm, arm64, csky, riscv, sh, and xtensa
> > > did not have SECCOMP on by default prior to this and SECCOMP will
> > > be default in this change.
> > >
> > > Architectures microblaze, mips, powerpc, s390, sh, and sparc
> > > have an outdated depend on PROC_FS and this dependency is removed
> > > in this change.
> > >
> > > Suggested-by: Jann Horn <jannh@google.com>
> > > Link: https://lore.kernel.org/lkml/CAG48ez1YWz9cnp08UZgeieYRhHdqh-ch7aNwc4JRBnGyrmgfMg@mail.gmail.com/
> > > Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>
> >
> > Thanks for your patch. which is now commit 282a181b1a0d66de ("seccomp:
> > Move config option SECCOMP to arch/Kconfig") in v5.10-rc1.
> >
> > > --- a/arch/Kconfig
> > > +++ b/arch/Kconfig
> > > @@ -458,6 +462,23 @@ config HAVE_ARCH_SECCOMP_FILTER
> > > results in the system call being skipped immediately.
> > > - seccomp syscall wired up
> > >
> > > +config SECCOMP
> > > + def_bool y
> > > + depends on HAVE_ARCH_SECCOMP
> > > + prompt "Enable seccomp to safely compute untrusted bytecode"
> > > + help
> > > + This kernel feature is useful for number crunching applications
> > > + that may need to compute untrusted bytecode during their
> > > + execution. By using pipes or other transports made available to
> > > + the process as file descriptors supporting the read/write
> > > + syscalls, it's possible to isolate those applications in
> > > + their own address space using seccomp. Once seccomp is
> > > + enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
> > > + and the task is only allowed to execute a few safe syscalls
> > > + defined by each seccomp mode.
> > > +
> > > + If unsure, say Y. Only embedded should say N here.
> > > +
> >
> > Please tell me why SECCOMP is special, and deserves to default to be
> > enabled. Is it really that critical, given only 13.5 (half of sparc
> > ;-) out of 24
> > architectures implement support for it?
>
> That's an excellent point; I missed this in my review as I saw several
> Kconfig already marked "def_bool y" but failed to note it wasn't _all_
> of them. Okay, checking before this patch, these had them effectively
> enabled:
>
> via Kconfig:
>
> parisc
> s390
> um
> x86
Mostly "server" and "desktop" platforms.
> via defconfig, roughly speaking:
>
> arm
> arm64
> sh
Note that these defconfigs are example configs, not meant for production.
E.g. arm/multi_v7_defconfig and arm64/defconfig enable about everything
for compile coverage.
> How about making the default depend on HAVE_ARCH_SECCOMP_FILTER?
>
> These have SECCOMP_FILTER support:
>
> arch/arm/Kconfig: select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
> arch/arm64/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/csky/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/mips/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/parisc/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/powerpc/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/riscv/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/s390/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/sh/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/um/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/x86/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
> arch/xtensa/Kconfig: select HAVE_ARCH_SECCOMP_FILTER
>
> So the "new" promotions would be:
>
> csky
> mips
> powerpc
> riscv
> xtensa
>
> Which would leave only these two:
>
> arch/microblaze/Kconfig: select HAVE_ARCH_SECCOMP
> arch/sparc/Kconfig: select HAVE_ARCH_SECCOMP if SPARC64
>
> At this point, given the ubiquity of seccomp usage (e.g. systemd), I
> guess it's not unreasonable to make it def_bool y?
Having support does not necessarily imply you want it enabled.
If systemd needs it (does it? I have Debian nfsroots with systemd,
without SECCOMP), you can enable it in the defconfig.
"Default y" is for things you cannot do without, unless you know
better.
Bloat-o-meter says enabling SECCOMP consumes only ca. 8 KiB
(on arm32), so perhaps "default y if !EXPERT"?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-10-29 0:28 UTC|newest]
Thread overview: 149+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 5:35 [RFC PATCH seccomp 0/2] seccomp: Add bitmap cache of arg-independent filter results that allow syscalls YiFei Zhu
2020-09-21 5:35 ` [RFC PATCH seccomp 1/2] seccomp/cache: Add "emulator" to check if filter is arg-dependent YiFei Zhu
2020-09-21 17:47 ` Jann Horn
2020-09-21 18:38 ` Jann Horn
2020-09-21 23:44 ` YiFei Zhu
2020-09-22 0:25 ` Jann Horn
2020-09-22 0:47 ` YiFei Zhu
2020-09-21 5:35 ` [RFC PATCH seccomp 2/2] seccomp/cache: Cache filter results that allow syscalls YiFei Zhu
2020-09-21 18:08 ` Jann Horn
2020-09-21 22:50 ` YiFei Zhu
2020-09-21 22:57 ` Jann Horn
2020-09-21 23:08 ` YiFei Zhu
2020-09-25 0:01 ` [PATCH v2 seccomp 2/6] asm/syscall.h: Add syscall_arches[] array Kees Cook
2020-09-25 0:15 ` Jann Horn
2020-09-25 0:18 ` Al Viro
2020-09-25 0:24 ` Jann Horn
2020-09-25 1:27 ` YiFei Zhu
2020-09-25 3:09 ` Kees Cook
2020-09-25 3:28 ` YiFei Zhu
2020-09-25 16:39 ` YiFei Zhu
2020-09-21 5:48 ` [RFC PATCH seccomp 0/2] seccomp: Add bitmap cache of arg-independent filter results that allow syscalls Sargun Dhillon
2020-09-21 7:13 ` YiFei Zhu
2020-09-21 8:30 ` Christian Brauner
2020-09-21 8:44 ` YiFei Zhu
2020-09-21 13:51 ` Tycho Andersen
2020-09-21 15:27 ` YiFei Zhu
2020-09-21 16:39 ` Tycho Andersen
2020-09-21 22:57 ` YiFei Zhu
2020-09-21 19:16 ` Jann Horn
[not found] ` <OF8837FC1A.5C0D4D64-ON852585EA.006B677F-852585EA.006BA663@notes.na.collabserv.com>
2020-09-21 19:45 ` Jann Horn
2020-09-23 19:26 ` Kees Cook
2020-09-23 22:54 ` YiFei Zhu
2020-09-24 6:52 ` Kees Cook
2020-09-24 12:06 ` [PATCH seccomp 0/6] " YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 1/6] seccomp: Move config option SECCOMP to arch/Kconfig YiFei Zhu
2020-09-24 12:06 ` YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 2/6] asm/syscall.h: Add syscall_arches[] array YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 3/6] seccomp/cache: Add "emulator" to check if filter is arg-dependent YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 4/6] seccomp/cache: Lookup syscall allowlist for fast path YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 5/6] selftests/seccomp: Compare bitmap vs filter overhead YiFei Zhu
2020-09-24 12:06 ` [PATCH seccomp 6/6] seccomp/cache: Report cache data through /proc/pid/seccomp_cache YiFei Zhu
2020-09-24 12:44 ` [PATCH v2 seccomp 0/6] seccomp: Add bitmap cache of arg-independent filter results that allow syscalls YiFei Zhu
2020-09-24 12:44 ` [PATCH v2 seccomp 1/6] seccomp: Move config option SECCOMP to arch/Kconfig YiFei Zhu
2020-09-24 19:11 ` Kees Cook
2020-10-27 9:52 ` Geert Uytterhoeven
2020-10-27 19:08 ` YiFei Zhu
2020-10-28 0:06 ` Kees Cook
2020-10-28 8:18 ` Geert Uytterhoeven [this message]
2020-10-28 9:34 ` Jann Horn
2020-09-24 12:44 ` [PATCH v2 seccomp 2/6] asm/syscall.h: Add syscall_arches[] array YiFei Zhu
2020-09-24 13:47 ` David Laight
2020-09-24 14:16 ` YiFei Zhu
2020-09-24 14:20 ` David Laight
2020-09-24 14:37 ` YiFei Zhu
2020-09-24 16:02 ` YiFei Zhu
2020-09-24 12:44 ` [PATCH v2 seccomp 3/6] seccomp/cache: Add "emulator" to check if filter is arg-dependent YiFei Zhu
2020-09-24 23:25 ` Kees Cook
2020-09-25 3:04 ` YiFei Zhu
2020-09-25 16:45 ` YiFei Zhu
2020-09-25 19:42 ` Kees Cook
2020-09-25 19:51 ` Andy Lutomirski
2020-09-25 20:37 ` Kees Cook
2020-09-25 21:07 ` Andy Lutomirski
2020-09-25 23:49 ` Kees Cook
2020-09-26 0:34 ` Andy Lutomirski
2020-09-26 1:23 ` YiFei Zhu
2020-09-26 2:47 ` Andy Lutomirski
2020-09-26 4:35 ` Kees Cook
2020-09-24 12:44 ` [PATCH v2 seccomp 4/6] seccomp/cache: Lookup syscall allowlist for fast path YiFei Zhu
2020-09-24 23:46 ` Kees Cook
2020-09-25 1:55 ` YiFei Zhu
2020-09-24 12:44 ` [PATCH v2 seccomp 5/6] selftests/seccomp: Compare bitmap vs filter overhead YiFei Zhu
2020-09-24 23:47 ` Kees Cook
2020-09-25 1:35 ` YiFei Zhu
2020-09-24 12:44 ` [PATCH v2 seccomp 6/6] seccomp/cache: Report cache data through /proc/pid/seccomp_cache YiFei Zhu
2020-09-24 23:56 ` Kees Cook
2020-09-25 3:11 ` YiFei Zhu
2020-09-25 3:26 ` Kees Cook
2020-09-30 15:19 ` [PATCH v3 seccomp 0/5] seccomp: Add bitmap cache of constant allow filter results YiFei Zhu
2020-09-30 15:19 ` [PATCH v3 seccomp 1/5] x86: Enable seccomp architecture tracking YiFei Zhu
2020-09-30 21:21 ` Kees Cook
2020-09-30 21:33 ` Jann Horn
2020-09-30 22:53 ` Kees Cook
2020-09-30 23:15 ` Jann Horn
2020-09-30 15:19 ` [PATCH v3 seccomp 2/5] seccomp/cache: Add "emulator" to check if filter is constant allow YiFei Zhu
2020-09-30 22:24 ` Jann Horn
2020-09-30 22:49 ` Kees Cook
2020-10-01 11:28 ` YiFei Zhu
2020-10-01 21:08 ` Jann Horn
2020-09-30 22:40 ` Kees Cook
2020-10-01 11:52 ` YiFei Zhu
2020-10-01 21:05 ` Kees Cook
2020-10-02 11:08 ` YiFei Zhu
2020-10-09 4:47 ` YiFei Zhu
2020-10-09 5:41 ` Kees Cook
2020-09-30 15:19 ` [PATCH v3 seccomp 3/5] seccomp/cache: Lookup syscall allowlist for fast path YiFei Zhu
2020-09-30 21:32 ` Kees Cook
2020-10-09 0:17 ` YiFei Zhu
2020-10-09 5:35 ` Kees Cook
2020-09-30 15:19 ` [PATCH v3 seccomp 4/5] selftests/seccomp: Compare bitmap vs filter overhead YiFei Zhu
2020-09-30 15:19 ` [PATCH v3 seccomp 5/5] seccomp/cache: Report cache data through /proc/pid/seccomp_cache YiFei Zhu
2020-09-30 22:00 ` Jann Horn
2020-09-30 23:12 ` Kees Cook
2020-10-01 12:06 ` YiFei Zhu
2020-10-01 16:05 ` Jann Horn
2020-10-01 16:18 ` YiFei Zhu
2020-09-30 22:59 ` Kees Cook
2020-09-30 23:08 ` Jann Horn
2020-09-30 23:21 ` Kees Cook
2020-10-09 17:14 ` [PATCH v4 seccomp 0/5] seccomp: Add bitmap cache of constant allow filter results YiFei Zhu
2020-10-09 17:14 ` [PATCH v4 seccomp 1/5] seccomp/cache: Lookup syscall allowlist bitmap for fast path YiFei Zhu
2020-10-09 21:30 ` Jann Horn
2020-10-09 23:18 ` Kees Cook
2020-10-09 17:14 ` [PATCH v4 seccomp 2/5] seccomp/cache: Add "emulator" to check if filter is constant allow YiFei Zhu
2020-10-09 21:30 ` Jann Horn
2020-10-09 22:47 ` Kees Cook
2020-10-09 17:14 ` [PATCH v4 seccomp 3/5] x86: Enable seccomp architecture tracking YiFei Zhu
2020-10-09 17:25 ` Andy Lutomirski
2020-10-09 18:32 ` YiFei Zhu
2020-10-09 20:59 ` Andy Lutomirski
2020-10-09 17:14 ` [PATCH v4 seccomp 4/5] selftests/seccomp: Compare bitmap vs filter overhead YiFei Zhu
2020-10-09 17:14 ` [PATCH v4 seccomp 5/5] seccomp/cache: Report cache data through /proc/pid/seccomp_cache YiFei Zhu
2020-10-09 21:45 ` Jann Horn
2020-10-09 23:14 ` Kees Cook
2020-10-10 13:26 ` YiFei Zhu
2020-10-12 22:57 ` Kees Cook
2020-10-13 0:31 ` YiFei Zhu
2020-10-22 20:52 ` YiFei Zhu
2020-10-22 22:32 ` Kees Cook
2020-10-22 23:40 ` YiFei Zhu
2020-10-24 2:51 ` Kees Cook
2020-10-30 12:18 ` YiFei Zhu
2020-11-03 13:00 ` YiFei Zhu
2020-11-04 0:29 ` Kees Cook
2020-11-04 11:40 ` YiFei Zhu
2020-11-04 18:57 ` Kees Cook
2020-10-11 15:47 ` [PATCH v5 seccomp 0/5]seccomp: Add bitmap cache of constant allow filter results YiFei Zhu
2020-10-11 15:47 ` [PATCH v5 seccomp 1/5] seccomp/cache: Lookup syscall allowlist bitmap for fast path YiFei Zhu
2020-10-12 6:42 ` Jann Horn
2020-10-11 15:47 ` [PATCH v5 seccomp 2/5] seccomp/cache: Add "emulator" to check if filter is constant allow YiFei Zhu
2020-10-12 6:46 ` Jann Horn
2020-10-11 15:47 ` [PATCH v5 seccomp 3/5] x86: Enable seccomp architecture tracking YiFei Zhu
2020-10-11 15:47 ` [PATCH v5 seccomp 4/5] selftests/seccomp: Compare bitmap vs filter overhead YiFei Zhu
2020-10-11 15:47 ` [PATCH v5 seccomp 5/5] seccomp/cache: Report cache data through /proc/pid/seccomp_cache YiFei Zhu
2020-10-12 6:49 ` Jann Horn
2020-12-17 12:14 ` Geert Uytterhoeven
2020-12-17 18:34 ` YiFei Zhu
2020-12-18 12:35 ` Geert Uytterhoeven
2020-10-27 19:14 ` [PATCH v5 seccomp 0/5]seccomp: Add bitmap cache of constant allow filter results Kees Cook
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