From patchwork Tue Oct 13 17:04:16 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Seth Forshee X-Patchwork-Id: 7386961 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 37E96BEEA4 for ; Tue, 13 Oct 2015 17:06:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6612C20767 for ; Tue, 13 Oct 2015 17:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7769620749 for ; Tue, 13 Oct 2015 17:06:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753277AbbJMRFd (ORCPT ); Tue, 13 Oct 2015 13:05:33 -0400 Received: from mail-ig0-f170.google.com ([209.85.213.170]:34835 "EHLO mail-ig0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753256AbbJMRF2 (ORCPT ); Tue, 13 Oct 2015 13:05:28 -0400 Received: by igbkq10 with SMTP id kq10so97069887igb.0 for ; Tue, 13 Oct 2015 10:05:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=++ffNWy9K/SPUwEYIi/wjELCWVoEiMnFuogd3EVCmSU=; b=fLzv1KomP0HjpibACm5laAdlWa5O2B4RGosGIMeK9StP1Bfmis8N6A1PbtOoddrGK3 my4bry9mAp5QhxbwKmHfJDn3OatmXLEqRHluDYOiCZV54PvX2Dxx3Vh3uJ3fdKQwwqEd RkvkfuHGA0rl69B8bzLwLMO8RNPCH/+UhZwBN2ZoBSjz1+REecKWm3atQbiPuz8L5GVl S7ZqwiB4MJMcE0Gpy/Nm9ab8z7TEMov14RxlvWJkpn6gLngtg8KBJMYkUa1BXoc5QziK P3WrxmfNtJnFjvy4JJ/42DcYqqhcRzzFZjllcpUhveF61CawA2QryALNX1/JRKTm5EhK icpA== X-Gm-Message-State: ALoCoQk5mIP7s/xIhaNHnydYiHkiuqbUMu4rCg4E0vxKoA/XuWETAQTXHulSDQxaUZm83p52z5Q/ X-Received: by 10.50.85.13 with SMTP id d13mr19576680igz.7.1444755927600; Tue, 13 Oct 2015 10:05:27 -0700 (PDT) Received: from localhost (199-87-125-144.dyn.kc.surewest.net. [199.87.125.144]) by smtp.gmail.com with ESMTPSA id f71sm1903193ioe.14.2015.10.13.10.05.26 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Tue, 13 Oct 2015 10:05:27 -0700 (PDT) From: Seth Forshee To: "Eric W. Biederman" , David Woodhouse , Brian Norris Cc: Alexander Viro , Serge Hallyn , Andy Lutomirski , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, Seth Forshee Subject: [PATCH v2 3/7] mtd: Check permissions towards mtd block device inode when mounting Date: Tue, 13 Oct 2015 12:04:16 -0500 Message-Id: <1444755861-54997-4-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1444755861-54997-1-git-send-email-seth.forshee@canonical.com> References: <1444755861-54997-1-git-send-email-seth.forshee@canonical.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Unprivileged users should not be able to mount mtd block devices when they lack sufficient privileges towards the block device inode. Update mount_mtd() to validate that the user has the required access to the inode at the specified path. The check will be skipped for CAP_SYS_ADMIN, so privileged mounts will continue working as before. Signed-off-by: Seth Forshee --- drivers/mtd/mtdsuper.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c index b5b60e1af31c..5d7e7705fed8 100644 --- a/drivers/mtd/mtdsuper.c +++ b/drivers/mtd/mtdsuper.c @@ -125,6 +125,7 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, #ifdef CONFIG_BLOCK struct block_device *bdev; int ret, major; + int perm; #endif int mtdnr; @@ -176,7 +177,10 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, /* try the old way - the hack where we allowed users to mount * /dev/mtdblock$(n) but didn't actually _use_ the blockdev */ - bdev = lookup_bdev(dev_name, 0); + perm = MAY_READ; + if (!(flags & MS_RDONLY)) + perm |= MAY_WRITE; + bdev = lookup_bdev(dev_name, perm); if (IS_ERR(bdev)) { ret = PTR_ERR(bdev); pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);