From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BD5AC73C66 for ; Sun, 14 Jul 2019 14:12:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4BB420644 for ; Sun, 14 Jul 2019 14:12:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728433AbfGNOKL (ORCPT ); Sun, 14 Jul 2019 10:10:11 -0400 Received: from vmicros1.altlinux.org ([194.107.17.57]:34800 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728126AbfGNOKL (ORCPT ); Sun, 14 Jul 2019 10:10:11 -0400 Received: from mua.local.altlinux.org (mua.local.altlinux.org [192.168.1.14]) by vmicros1.altlinux.org (Postfix) with ESMTP id 605F772CA65; Sun, 14 Jul 2019 17:10:08 +0300 (MSK) Received: by mua.local.altlinux.org (Postfix, from userid 508) id 3C70B7CCE3A; Sun, 14 Jul 2019 17:10:08 +0300 (MSK) Date: Sun, 14 Jul 2019 17:10:08 +0300 From: "Dmitry V. Levin" To: Christian Brauner Cc: Anatoly Pugachev , linux-kernel@vger.kernel.org Subject: Re: [PATCH] clone: fix CLONE_PIDFD support Message-ID: <20190714141007.GA9131@altlinux.org> References: <20190714120206.GC6773@altlinux.org> <20190714121724.mwg2t3di6goha7yq@brauner.io> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/9DWx/yDrRhgMJTb" Content-Disposition: inline In-Reply-To: <20190714121724.mwg2t3di6goha7yq@brauner.io> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --/9DWx/yDrRhgMJTb Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Jul 14, 2019 at 02:17:25PM +0200, Christian Brauner wrote: > On Sun, Jul 14, 2019 at 03:02:06PM +0300, Dmitry V. Levin wrote: > > The introduction of clone3 syscall accidentally broke CLONE_PIDFD > > support in traditional clone syscall on compat x86 and those > > architectures that use do_fork to implement clone syscall. > >=20 > > This bug was found by strace test suite. > >=20 > > Link: https://strace.io/logs/strace/2019-07-12 > > Fixes: 7f192e3cd316 ("fork: add clone3") > > Bisected-and-tested-by: Anatoly Pugachev > > Signed-off-by: Dmitry V. Levin >=20 > Good catch! Thank you Dmitry. >=20 > One change request below. >=20 > > --- > > arch/x86/ia32/sys_ia32.c | 1 + > > kernel/fork.c | 1 + > > 2 files changed, 2 insertions(+) > >=20 > > diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c > > index 64a6c952091e..98754baf411a 100644 > > --- a/arch/x86/ia32/sys_ia32.c > > +++ b/arch/x86/ia32/sys_ia32.c > > @@ -239,6 +239,7 @@ COMPAT_SYSCALL_DEFINE5(x86_clone, unsigned long, cl= one_flags, > > { > > struct kernel_clone_args args =3D { > > .flags =3D (clone_flags & ~CSIGNAL), > > + .pidfd =3D parent_tidptr, > > .child_tid =3D child_tidptr, > > .parent_tid =3D parent_tidptr, > > .exit_signal =3D (clone_flags & CSIGNAL), > > diff --git a/kernel/fork.c b/kernel/fork.c > > index 8f3e2d97d771..2c3cbad807b6 100644 > > --- a/kernel/fork.c > > +++ b/kernel/fork.c > > @@ -2417,6 +2417,7 @@ long do_fork(unsigned long clone_flags, > > { > > struct kernel_clone_args args =3D { > > .flags =3D (clone_flags & ~CSIGNAL), > > + .pidfd =3D parent_tidptr, > > .child_tid =3D child_tidptr, > > .parent_tid =3D parent_tidptr, > > .exit_signal =3D (clone_flags & CSIGNAL), > > --=20 >=20 > Both of these legacy clone helpers need to make CLONE_PIDFD and > CLONE_PARENT_SETTID incompatible, i.e. could you please add a helper to > kernel/fork.c: >=20 > bool legacy_clone_args_valid(const struct kernel_clone_args *kargs) > { > /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */ > if ((kargs->flags & CLONE_PIDFD) && (kargs->flags & CLONE_PARENT_SETTID)) > return false; > } >=20 > and export it and use it in ia32 too? copy_process already performs the check, isn't this enough? Also, the check in sys_clone looks redundant and I was going to suggest its removal. --=20 ldv --/9DWx/yDrRhgMJTb Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJdKze/AAoJEAVFT+BVnCUIIaQP/RtgRfoyaDZT9i/PEHjdNOus ni5nRr2a/I9Q7wT9KjX9ywSnLf33UooFR/cRd4YW5TsTzwjldM2LmJQz0FU76/C2 fGzmWAj6YGCy40KxDnKT20vtuOZij+OxLEW02qIhKN0OcSJgZ9wOVBdo9l+Rhz5A dnTIr5feKqZhfuQ/j0Q5/vpEOs61muOHuWSigKdkZB2YGLxPv1QH+0Qtc6z9wdNb X8WEU7xhEDVF5Iksx2YDgSkUzFr52cTPJcUnJeoEfAkVkgmvHYUa0+1Uv1Yrmjqp yzb6zdLvRSMsV/depkvyf91vPrM+3HuLahGcq3SwTT5Z7WkZkgfFhifP1FT7eUZb 44y6EHBWg1pWSrGP2nsyw5ZuO/JSWjtVzMhjGJSkVXRGqZlQWSOijlS5sLkINXAP UYGohnYJyrhc6tI7oRz11SC8cnELBWD36Vn7dn9N/WeAzyJj8ksucETEaaU0JlCx 523fK1O0ou7VKL+WCEtQfnHulWWvWq7pJl04p713Uvz5velOzOKnoqztkIuw7hTP HgHC3f/EUHN/dPXOmrF2AGfYYV0DKnViMyIDm5NbrzYYRFHuvq//g6Aqe2jARc8u HMODrPQbXYCNzpz5UlrZGiqhh0m1dnSIIWAF1Cx+aQE95ghD+2QyVZQK40m0piLk Tv/l/GbhUTxHULTPYrJm =xKje -----END PGP SIGNATURE----- --/9DWx/yDrRhgMJTb--