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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 99329C433E0 for ; Fri, 22 Jan 2021 18:56:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56E6523AC8 for ; Fri, 22 Jan 2021 18:56:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730276AbhAVSxj (ORCPT ); Fri, 22 Jan 2021 13:53:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:39308 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728522AbhAVOWD (ORCPT ); Fri, 22 Jan 2021 09:22:03 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1C04B23AC8; Fri, 22 Jan 2021 14:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611324970; bh=FF0Eut46PKr87ElysybdlIYlogJYoUuULboTnAlfkaY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yI6PnkmQyHGgszXWl6nJWosdALdtl47bTzb5IQxpXOrVlL/PAMd2ZK2bWtiXorDhV jTARZs0srqWcEH1+R3izEhOtiyxH1X8PhMaZPpFNK+NliAVMHHdjRMEo9HNvUzggv7 0SRyRktkNtch5mrbKVFQreM9xE9YiGUJnbjUpqhs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Youjipeng , "J. Bruce Fields" , Chuck Lever Subject: [PATCH 4.19 05/22] nfsd4: readdirplus shouldnt return parent of export Date: Fri, 22 Jan 2021 15:12:23 +0100 Message-Id: <20210122135732.135933562@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210122135731.921636245@linuxfoundation.org> References: <20210122135731.921636245@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: J. Bruce Fields commit 51b2ee7d006a736a9126e8111d1f24e4fd0afaa6 upstream. If you export a subdirectory of a filesystem, a READDIRPLUS on the root of that export will return the filehandle of the parent with the ".." entry. The filehandle is optional, so let's just not return the filehandle for ".." if we're at the root of an export. Note that once the client learns one filehandle outside of the export, they can trivially access the rest of the export using further lookups. However, it is also not very difficult to guess filehandles outside of the export. So exporting a subdirectory of a filesystem should considered equivalent to providing access to the entire filesystem. To avoid confusion, we recommend only exporting entire filesystems. Reported-by: Youjipeng Signed-off-by: J. Bruce Fields Cc: stable@vger.kernel.org Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs3xdr.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/nfsd/nfs3xdr.c +++ b/fs/nfsd/nfs3xdr.c @@ -844,9 +844,14 @@ compose_entry_fh(struct nfsd3_readdirres if (isdotent(name, namlen)) { if (namlen == 2) { dchild = dget_parent(dparent); - /* filesystem root - cannot return filehandle for ".." */ + /* + * Don't return filehandle for ".." if we're at + * the filesystem or export root: + */ if (dchild == dparent) goto out; + if (dparent == exp->ex_path.dentry) + goto out; } else dchild = dget(dparent); } else