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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 8ADDFC433DF for ; Sun, 17 May 2020 11:22:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C86C206D4 for ; Sun, 17 May 2020 11:22:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727893AbgEQLWG (ORCPT ); Sun, 17 May 2020 07:22:06 -0400 Received: from mx2.suse.de ([195.135.220.15]:43750 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727858AbgEQLWG (ORCPT ); Sun, 17 May 2020 07:22:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 96586AC53; Sun, 17 May 2020 11:22:07 +0000 (UTC) Date: Sun, 17 May 2020 21:21:56 +1000 From: Aleksa Sarai To: Christian Brauner Cc: Kees Cook , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] seccomp: Add group_leader pid to seccomp_notif Message-ID: <20200517112156.cphs2h33hx2wfcs4@yavin.dot.cyphar.com> References: <20200515234005.32370-1-sargun@sargun.me> <202005162344.74A02C2D@keescook> <20200517104701.bbn2d2rqaplwchdw@wittgenstein> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nwxvb3yzfbh4rrle" Content-Disposition: inline In-Reply-To: <20200517104701.bbn2d2rqaplwchdw@wittgenstein> Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org --nwxvb3yzfbh4rrle Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2020-05-17, Christian Brauner wrote: > Or... And that's more invasive but ultimately cleaner we v2 the whole > thing so e.g. SECCOMP_IOCTL_NOTIF_RECV2, SECCOMP_IOCTL_NOTIF_SEND2, and > embedd the size argument in the structs. Userspace sets the size > argument, we use get_user() to get the size first and then > copy_struct_from_user() to handle it cleanly based on that. A similar > model as with sched (has other unrelated quirks because they messed up > something too): >=20 > static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_= attr *attr) > { > u32 size; > int ret; >=20 > /* Zero the full structure, so that a short copy will be nice: */ > memset(attr, 0, sizeof(*attr)); >=20 > ret =3D get_user(size, &uattr->size); > if (ret) > return ret; >=20 > /* ABI compatibility quirk: */ > if (!size) > size =3D SCHED_ATTR_SIZE_VER0; > if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE) > goto err_size; >=20 > ret =3D copy_struct_from_user(attr, sizeof(*attr), uattr, size); > if (ret) { > if (ret =3D=3D -E2BIG) > goto err_size; > return ret; > } >=20 > We're probably the biggest user of this right now and I'd be ok with > that change. If it's a v2 than whatever. :) I'm :+1: on a new version and switch to copy_struct_from_user(). I was a little surprised when I found out that user_notif doesn't do it this way a while ago (and although in theory it is userspace's fault, ideally we could have an API that doesn't have built-in footguns). --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nwxvb3yzfbh4rrle Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEXzbGxhtUYBJKdfWmnhiqJn3bjbQFAl7BHlEACgkQnhiqJn3b jbR9pRAAnO1r26da3EnqUIDsjxOHWMLuwpB3QN+k925fWG47jt706mzLU1duX8EG V8hWXeSYIX8Fk+tWv7dbb6xl4uYF18wvZUX3EZFROQUZKiLqjQSSJUKs05IpdZwl cvXwIvzMM3xv9qc8NHQoK8D0GQkbdem8Oaxd8n2VNHL2eYirDENb62xcr1vLjp2b psvcpgXWoPKr8m8wyY3NZsXcbJwLg77qQDN+1jjHjnBLXhSVugnMbR1aXFtWsYh8 bAYFv7Rq0nv0+bqnyxKSL3lfgyuraZCz4ZF8NlyTnFIbUmtJrHEAF7ykT1wvfjXk SP/gntWDRKm2QLLr8JnAPtrp1sXXEqRBLmltK8BRtc597YSG5jrz+Lwt4mwRbpf8 EvfLqeBXZNVEZSdS5Zvjl93ryCK9yyE9eiRdZPsKFuoUPmipXlp52WRp9ldCj9Rm JF7P4qarU5MSWLNMb8V1LC6BSPUDd88EfbsA6OaQ/HSkVaV2ueNzyJRxIYChu/se 20gfe9+VR4nS4Iys0AL1pzeg18yKJdCNqR0rg+Iaj64gjANmEX6QiJwluaOcw8Dh fl60XE5LZzOe5N2wy1vKaRkcAP/IMmm7OFGd97QWrG2bPoX/VDpDE59pTpkaHk2H rhR+vla/f6OXERSCd0F4QWYIxcNSs9Um0STXyT7iQhWDpLM/IKY= =Huyx -----END PGP SIGNATURE----- --nwxvb3yzfbh4rrle--