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 3A392C04A6B for ; Mon, 6 May 2019 14:50:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AC7F2053B for ; Mon, 6 May 2019 14:50:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557154229; bh=qW0yTp0Bkwnm33rylBQl14Ex1/xlNSpFb9hZF9+Snsc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HV1WAGSzcWvxIp3cPNU13bAcxZYkPqS5NYYZqXN+/a4FQLNKQmHVNRw8IQ2g5QKSp hU0UWU45/Lvs5xF1c0N41d5iOuCy1Ch7PQX+K2ICGbZ/Scapll6Sq+TF5yStlPHPiy IrMPf+UnCCEXRKi2xbBBUQFSrE7pPQTESOymn1X4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727068AbfEFOtY (ORCPT ); Mon, 6 May 2019 10:49:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:50864 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726985AbfEFOtX (ORCPT ); Mon, 6 May 2019 10:49:23 -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 F04D121019; Mon, 6 May 2019 14:49:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557154162; bh=qW0yTp0Bkwnm33rylBQl14Ex1/xlNSpFb9hZF9+Snsc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wXv8VZ3D23gRk57JxVQqb5kQ/v1APK7NibJPWqfyhZcRa0Um65Ws6VdPDcdrpA4iA yXNZ9mlY0hOuiRwv8wYfTUOPpezSXMp6KcuZH6N7U6fM811Zhb6fPzTWPYFf10tCQe +5kAbamJR/bVFgf39Ivb+XPNmwzsTjhdVPSm5Vzs= 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 4.9 60/62] selinux: never allow relabeling on context mounts Date: Mon, 6 May 2019 16:33:31 +0200 Message-Id: <20190506143056.624747476@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190506143051.102535767@linuxfoundation.org> References: <20190506143051.102535767@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 @@ -467,21 +467,43 @@ 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, "rootfs"); } +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;