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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 B7922C43331 for ; Mon, 11 Nov 2019 15:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AE67214E0 for ; Mon, 11 Nov 2019 15:25:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aNrxQL7t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726952AbfKKPZ2 (ORCPT ); Mon, 11 Nov 2019 10:25:28 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51629 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726832AbfKKPZ2 (ORCPT ); Mon, 11 Nov 2019 10:25:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1573485926; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RTpgrGON4kavQjrqlqN+As1k4CmcekptcYakwUxrssY=; b=aNrxQL7t5MpgXV37oFxbAuRYh9yOJwxNGsU2WtcJlwiM4J0O6smV1OGIsa/rO+3f950JGd 9MAzmvWE9okOhw45rEstlh7ly91KghitCT4+bN5Kuv2GDUI3mjpjqSAUOwZWlB6a2awFmf 1vQuTG4xDgGQspX+GXWJs+VgxT9v9xE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-386-lGc3MC08MDKlQT_hnW38rw-1; Mon, 11 Nov 2019 10:25:21 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 78A3F8EBAC9; Mon, 11 Nov 2019 15:25:19 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.44]) by smtp.corp.redhat.com (Postfix) with SMTP id 4938619C4F; Mon, 11 Nov 2019 15:25:15 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 11 Nov 2019 16:25:19 +0100 (CET) Date: Mon, 11 Nov 2019 16:25:15 +0100 From: Oleg Nesterov To: Adrian Reber Cc: Christian Brauner , Eric Biederman , Pavel Emelyanov , Jann Horn , Dmitry Safonov <0x7f454c46@gmail.com>, linux-kernel@vger.kernel.org, Andrei Vagin , Mike Rapoport , Radostin Stoyanov Subject: Re: [PATCH v7 1/2] fork: extend clone3() to support setting a PID Message-ID: <20191111152514.GA11389@redhat.com> References: <20191111131704.656169-1-areber@redhat.com> MIME-Version: 1.0 In-Reply-To: <20191111131704.656169-1-areber@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: lGc3MC08MDKlQT_hnW38rw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/11, Adrian Reber wrote: > > v7: > - changed set_tid to be an array to set the PID of a process > in multiple nested PID namespaces at the same time as discussed > at LPC 2019 (container MC) cough... iirc you convinced me this is not needed when we discussed the previous version ;) Nevermind, probably my memory fools me. So far I only have some cosmetic nits, > @@ -175,6 +187,18 @@ struct pid *alloc_pid(struct pid_namespace *ns) > > =09for (i =3D ns->level; i >=3D 0; i--) { > =09=09int pid_min =3D 1; > +=09=09int t_pos =3D 0; ^^^^^ I won't insist, but I'd suggest to cache set_tid[t_pos] instead to make the code a bit more simple. > @@ -186,12 +210,24 @@ struct pid *alloc_pid(struct pid_namespace *ns) > =09=09if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS) > =09=09=09pid_min =3D RESERVED_PIDS; You can probably move this code into the "else" branch below. IOW, something like =09for (i =3D ns->level; i >=3D 0; i--) { =09=09int xxx =3D 0; =09=09if (set_tid_size) { =09=09=09int pos =3D ns->level - i; =09=09=09xxx =3D set_tid[pos]; =09=09=09if (xxx < 1 || xxx >=3D pid_max) =09=09=09=09return ERR_PTR(-EINVAL); =09=09=09/* Also fail if a PID !=3D 1 is requested and no PID 1 exists */ =09=09=09if (xxx !=3D 1 && !tmp->child_reaper) =09=09=09=09return ERR_PTR(-EINVAL); =09=09=09if (!ns_capable(tmp->user_ns, CAP_SYS_ADMIN)) =09=09=09=09return ERR_PTR(-EPERM); =09=09=09set_tid_size--; =09=09} =09=09idr_preload(GFP_KERNEL); =09=09spin_lock_irq(&pidmap_lock); =09=09if (xxx) { =09=09=09nr =3D idr_alloc(&tmp->idr, NULL, xxx, xxx + 1, =09=09=09=09=09GFP_ATOMIC); =09=09=09/* =09=09=09 * If ENOSPC is returned it means that the PID is =09=09=09 * alreay in use. Return EEXIST in that case. =09=09=09 */ =09=09=09if (nr =3D=3D -ENOSPC) =09=09=09=09nr =3D -EEXIST; =09=09} else { =09=09=09int pid_min =3D 1; =09=09=09/* =09=09=09 * init really needs pid 1, but after reaching the =09=09=09 * maximum wrap back to RESERVED_PIDS =09=09=09 */ =09=09=09if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS) =09=09=09=09pid_min =3D RESERVED_PIDS; =09=09=09/* =09=09=09 * Store a null pointer so find_pid_ns does not find =09=09=09 * a partially initialized PID (see below). =09=09=09 */ =09=09=09nr =3D idr_alloc_cyclic(&tmp->idr, NULL, pid_min, =09=09=09=09=09 pid_max, GFP_ATOMIC); =09=09} =09=09... This way only the "if (set_tid_size)" block has to play with set_tid_size/s= et_tid. note also that this way we can easily allow set_tid[some_level] =3D=3D 0, w= e can simply do =09-=09if (xxx < 1 || xxx >=3D pid_max) =09+=09if (xxx < 0 || xxx >=3D pid_max) although I don't think this is really useful. Oleg.