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 4F347C433F5 for ; Wed, 24 Nov 2021 14:01:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243511AbhKXOEi (ORCPT ); Wed, 24 Nov 2021 09:04:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:51224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350650AbhKXOA4 (ORCPT ); Wed, 24 Nov 2021 09:00:56 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8B640632F7; Wed, 24 Nov 2021 13:09:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637759385; bh=ma3+/MsV3dPimc2kWHKUSKOiOxAkRuw68gL41V3FpRE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dxG+sB4/Mi1Xzb7qI/Lw9pXSF+CVQtAk2Arul8MTdAiVEWNdjTMfVySwL644/bzZE OO4qV4qH8G7X9pXc5Zo6p3HtspuiBttdft/6c/KKY0GwCNNITYGHrDl+aERTvolSMh iYR68y1XohbD8Ub6YDrlSfqISamX+Va9vhBN+i+I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alistair Delva , Khazhismel Kumykov , Bart Van Assche , Serge Hallyn , Jens Axboe , Paul Moore , selinux@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@android.com Subject: [PATCH 5.15 222/279] block: Check ADMIN before NICE for IOPRIO_CLASS_RT Date: Wed, 24 Nov 2021 12:58:29 +0100 Message-Id: <20211124115726.409329172@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115718.776172708@linuxfoundation.org> References: <20211124115718.776172708@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alistair Delva commit 94c4b4fd25e6c3763941bdec3ad54f2204afa992 upstream. Booting to Android userspace on 5.14 or newer triggers the following SELinux denial: avc: denied { sys_nice } for comm="init" capability=23 scontext=u:r:init:s0 tcontext=u:r:init:s0 tclass=capability permissive=0 Init is PID 0 running as root, so it already has CAP_SYS_ADMIN. For better compatibility with older SEPolicy, check ADMIN before NICE. Fixes: 9d3a39a5f1e4 ("block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE") Signed-off-by: Alistair Delva Cc: Khazhismel Kumykov Cc: Bart Van Assche Cc: Serge Hallyn Cc: Jens Axboe Cc: Greg Kroah-Hartman Cc: Paul Moore Cc: selinux@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: stable@vger.kernel.org # v5.14+ Reviewed-by: Bart Van Assche Acked-by: Serge Hallyn Link: https://lore.kernel.org/r/20211115181655.3608659-1-adelva@google.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/ioprio.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/block/ioprio.c +++ b/block/ioprio.c @@ -69,7 +69,14 @@ int ioprio_check_cap(int ioprio) switch (class) { case IOPRIO_CLASS_RT: - if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN)) + /* + * Originally this only checked for CAP_SYS_ADMIN, + * which was implicitly allowed for pid 0 by security + * modules such as SELinux. Make sure we check + * CAP_SYS_ADMIN first to avoid a denial/avc for + * possibly missing CAP_SYS_NICE permission. + */ + if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE)) return -EPERM; fallthrough; /* rt has prio field too */