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=-5.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 09D26C04A6B for ; Mon, 6 May 2019 14:54:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF6422054F for ; Mon, 6 May 2019 14:54:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557154490; bh=QBSunIwk2sq53lut5q3wAM4APzM6eYRPvuu1yZg2/pM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HGyxCsHYRuwokma2Ab6sa+Nrmjdqe2FJjZIPfZ8euenmXaHD634po8lNhbQMu4M9F NMpt9FRcYdE9pP+cLDxRXS/MHCGy7RfqHZ8r7L00sSThie0aQFy/DAI0M5Fzy9vwjh gaxNUrs/Yn6rBYmkkYQPgx4lPPxxW/2RRXVVHvtw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729132AbfEFOq1 (ORCPT ); Mon, 6 May 2019 10:46:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:44268 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729124AbfEFOq0 (ORCPT ); Mon, 6 May 2019 10:46:26 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CF03F20C01; Mon, 6 May 2019 14:46:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557153985; bh=QBSunIwk2sq53lut5q3wAM4APzM6eYRPvuu1yZg2/pM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xE4O6QLzQbo4ct55Y42pfYb/u1WU1B0ZdSeQDf+iGB471UCSXBuU0CG4zjVh1yUlx 4XVmYFijagFaVu6facf1y86XWxOdlTyeu6i9WRIlaFehD3C1lM9+MLADHMoaaNkjGD H7ldTo36Jtz0L//iNnnAjddLMwQ061h882dqddas= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ondrej Mosnacek , Stephen Smalley , Paul Moore Subject: [PATCH 4.14 70/75] selinux: never allow relabeling on context mounts Date: Mon, 6 May 2019 16:33:18 +0200 Message-Id: <20190506143059.606606075@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190506143053.287515952@linuxfoundation.org> References: <20190506143053.287515952@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ondrej Mosnacek commit a83d6ddaebe541570291205cb538e35ad4ff94f9 upstream. In the SECURITY_FS_USE_MNTPOINT case we never want to allow relabeling files/directories, so we should never set the SBLABEL_MNT flag. The 'special handling' in selinux_is_sblabel_mnt() is only intended for when the behavior is set to SECURITY_FS_USE_GENFS. While there, make the logic in selinux_is_sblabel_mnt() more explicit and add a BUILD_BUG_ON() to make sure that introducing a new SECURITY_FS_USE_* forces a review of the logic. Fixes: d5f3a5f6e7e7 ("selinux: add security in-core xattr support for pstore and debugfs") Signed-off-by: Ondrej Mosnacek Reviewed-by: Stephen Smalley Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- security/selinux/hooks.c | 40 +++++++++++++++++++++++++++++++--------- 1 file changed, 31 insertions(+), 9 deletions(-) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -471,16 +471,10 @@ static int may_context_mount_inode_relab return rc; } -static int selinux_is_sblabel_mnt(struct super_block *sb) +static int selinux_is_genfs_special_handling(struct super_block *sb) { - struct superblock_security_struct *sbsec = sb->s_security; - - return sbsec->behavior == SECURITY_FS_USE_XATTR || - sbsec->behavior == SECURITY_FS_USE_TRANS || - sbsec->behavior == SECURITY_FS_USE_TASK || - sbsec->behavior == SECURITY_FS_USE_NATIVE || - /* Special handling. Genfs but also in-core setxattr handler */ - !strcmp(sb->s_type->name, "sysfs") || + /* Special handling. Genfs but also in-core setxattr handler */ + return !strcmp(sb->s_type->name, "sysfs") || !strcmp(sb->s_type->name, "pstore") || !strcmp(sb->s_type->name, "debugfs") || !strcmp(sb->s_type->name, "tracefs") || @@ -490,6 +484,34 @@ static int selinux_is_sblabel_mnt(struct !strcmp(sb->s_type->name, "cgroup2"))); } +static int selinux_is_sblabel_mnt(struct super_block *sb) +{ + struct superblock_security_struct *sbsec = sb->s_security; + + /* + * IMPORTANT: Double-check logic in this function when adding a new + * SECURITY_FS_USE_* definition! + */ + BUILD_BUG_ON(SECURITY_FS_USE_MAX != 7); + + switch (sbsec->behavior) { + case SECURITY_FS_USE_XATTR: + case SECURITY_FS_USE_TRANS: + case SECURITY_FS_USE_TASK: + case SECURITY_FS_USE_NATIVE: + return 1; + + case SECURITY_FS_USE_GENFS: + return selinux_is_genfs_special_handling(sb); + + /* Never allow relabeling on context mounts */ + case SECURITY_FS_USE_MNTPOINT: + case SECURITY_FS_USE_NONE: + default: + return 0; + } +} + static int sb_finish_set_opts(struct super_block *sb) { struct superblock_security_struct *sbsec = sb->s_security;