From nobody Thu Apr 2 21:45:33 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7887CC32771 for ; Wed, 21 Sep 2022 10:42:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230364AbiIUKmZ (ORCPT ); Wed, 21 Sep 2022 06:42:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229641AbiIUKmN (ORCPT ); Wed, 21 Sep 2022 06:42:13 -0400 Received: from us-smtp-delivery-44.mimecast.com (us-smtp-delivery-44.mimecast.com [207.211.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D301310564 for ; Wed, 21 Sep 2022 03:42:08 -0700 (PDT) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-631-DGMXSy5cObOiTx5N5XIHaA-1; Wed, 21 Sep 2022 06:42:06 -0400 X-MC-Unique: DGMXSy5cObOiTx5N5XIHaA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id ECC05801231; Wed, 21 Sep 2022 10:42:05 +0000 (UTC) Received: from comp-core-i7-2640m-0182e6.redhat.com (unknown [10.40.208.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 971971759F; Wed, 21 Sep 2022 10:42:04 +0000 (UTC) From: Alexey Gladkov To: LKML , Linux Containers Cc: Andrew Morton , Christian Brauner , "Eric W . Biederman" , Kees Cook , Manfred Spraul Subject: [PATCH v3 2/3] sysctl: Allow to change limits for posix messages queues Date: Wed, 21 Sep 2022 12:41:48 +0200 Message-Id: <7eb21211c8622e91d226e63416b1b93c079f60ee.1663756794.git.legion@kernel.org> In-Reply-To: References: <202209211737.0Bu0F40t-lkp@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" All parameters of posix messages queues (queues_max/msg_max/msgsize_max) end up being limited by RLIMIT_MSGQUEUE. The code in mqueue_get_inode is where that limiting happens. The RLIMIT_MSGQUEUE is bound to the user namespace and is counted hierarchically. We can allow root in the user namespace to modify the posix messages queues parameters. Signed-off-by: Alexey Gladkov --- ipc/mq_sysctl.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c index fbf6a8b93a26..ff1054fbbacc 100644 --- a/ipc/mq_sysctl.c +++ b/ipc/mq_sysctl.c @@ -12,6 +12,7 @@ #include #include #include +#include =20 static int msg_max_limit_min =3D MIN_MSGMAX; static int msg_max_limit_max =3D HARD_MSGMAX; @@ -76,8 +77,43 @@ static int set_is_seen(struct ctl_table_set *set) return ¤t->nsproxy->ipc_ns->mq_set =3D=3D set; } =20 +static void mq_set_ownership(struct ctl_table_header *head, + struct ctl_table *table, + kuid_t *uid, kgid_t *gid) +{ + struct ipc_namespace *ns =3D + container_of(head->set, struct ipc_namespace, mq_set); + + kuid_t ns_root_uid =3D make_kuid(ns->user_ns, 0); + kgid_t ns_root_gid =3D make_kgid(ns->user_ns, 0); + + *uid =3D uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID; + *gid =3D gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID; +} + +static int mq_permissions(struct ctl_table_header *head, struct ctl_table = *table) +{ + int mode =3D table->mode; + kuid_t ns_root_uid; + kgid_t ns_root_gid; + + mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid); + + if (uid_eq(current_euid(), ns_root_uid)) + mode >>=3D 6; + + if (in_egroup_p(ns_root_gid)) + mode >>=3D 3; + + mode &=3D 7; + + return (mode << 6) | (mode << 3) | mode; +} + static struct ctl_table_root set_root =3D { .lookup =3D set_lookup, + .permissions =3D mq_permissions, + .set_ownership =3D mq_set_ownership, }; =20 bool setup_mq_sysctls(struct ipc_namespace *ns) --=20 2.33.4