From patchwork Sun Mar 2 16:06:43 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Christian_G=C3=B6ttsche?= X-Patchwork-Id: 13998018 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D32CBC19F32 for ; Sun, 2 Mar 2025 21:50:24 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3984410E061; Sun, 2 Mar 2025 21:50:24 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=seltendoof.de header.i=@seltendoof.de header.b="L00+6xuu"; dkim-atps=neutral X-Greylist: delayed 452 seconds by postgrey-1.36 at gabe; Sun, 02 Mar 2025 16:14:49 UTC Received: from server02.seltendoof.de (server02.seltendoof.de [168.119.48.163]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6F4DC10E144 for ; Sun, 2 Mar 2025 16:14:49 +0000 (UTC) From: =?utf-8?q?Christian_G=C3=B6ttsche?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=seltendoof.de; s=2023072701; t=1740931630; h=from:from:reply-to: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=m7tEjDSgKvohdvK6pTN+ndS8THOOnhPlPkLJOHpGmuo=; b=L00+6xuuwiWduCv+ixkmgNqzMue8FepzjU+fPTpLl3F5QZOO27bk7M9wmhhWU8jT4crfSL M/7o09GRptVOm+HsIO9YOzFhbaHCvz9w2ZOEuXxwGv+gKYE2NJQPPMme+A8tlGmNwEs9Hc zPxhTr1xrvSbV+1FwKr4ooR3KG+Nuqah7c8wXDMWW23rsD/wuGMhE+XSSuxU6acEaBKxjU SMoreM+GacqhtPwtqg8XONVAirj0PqdKl+b+IaRgbRc9E8o6K0amJ1WFuaGVHcfzBkbpnz CSZFhosDGBLKiF2l0uokkI6/gp4rmRVY4ARa7sYCKIATyzRBtNmg19WhoyltuQ== To: Cc: =?utf-8?q?Christian_G=C3=B6ttsche?= , Serge Hallyn , Jan Kara , Julia Lawall , Nicolas Palix , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, cocci@inria.fr, Liviu Dudau , Boris Brezillon , Steven Price , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org Subject: [PATCH v2 07/11] drm/panthor: reorder capability check last Date: Sun, 2 Mar 2025 17:06:43 +0100 Message-ID: <20250302160657.127253-6-cgoettsche@seltendoof.de> In-Reply-To: <20250302160657.127253-1-cgoettsche@seltendoof.de> References: <20250302160657.127253-1-cgoettsche@seltendoof.de> MIME-Version: 1.0 X-Mailman-Approved-At: Sun, 02 Mar 2025 21:50:23 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: cgzones@googlemail.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Christian Göttsche capable() calls refer to enabled LSMs whether to permit or deny the request. This is relevant in connection with SELinux, where a capability check results in a policy decision and by default a denial message on insufficient permission is issued. It can lead to three undesired cases: 1. A denial message is generated, even in case the operation was an unprivileged one and thus the syscall succeeded, creating noise. 2. To avoid the noise from 1. the policy writer adds a rule to ignore those denial messages, hiding future syscalls, where the task performs an actual privileged operation, leading to hidden limited functionality of that task. 3. To avoid the noise from 1. the policy writer adds a rule to permit the task the requested capability, while it does not need it, violating the principle of least privilege. Signed-off-by: Christian Göttsche Reviewed-by: Serge Hallyn Reviewed-by: Liviu Dudau --- v2: split from previous patch with unrelated subsystem --- drivers/gpu/drm/panthor/panthor_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c index 08136e790ca0..76a10121f8a8 100644 --- a/drivers/gpu/drm/panthor/panthor_drv.c +++ b/drivers/gpu/drm/panthor/panthor_drv.c @@ -791,7 +791,7 @@ static int group_priority_permit(struct drm_file *file, return 0; /* Higher priorities require CAP_SYS_NICE or DRM_MASTER */ - if (capable(CAP_SYS_NICE) || drm_is_current_master(file)) + if (drm_is_current_master(file) || capable(CAP_SYS_NICE)) return 0; return -EACCES;