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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76BEAC433EF for ; Thu, 30 Sep 2021 07:53:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 551DD61527 for ; Thu, 30 Sep 2021 07:53:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348801AbhI3HzW (ORCPT ); Thu, 30 Sep 2021 03:55:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:58478 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348793AbhI3HzV (ORCPT ); Thu, 30 Sep 2021 03:55:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1B5D961452; Thu, 30 Sep 2021 07:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632988419; bh=wfufoGrDSlfUs9Me8/1bNDZ0YZoqlCww6ODrn49dbNg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GNI69UF4V1CvlWRm/QV6RJYhAKi4GlTMlqxuNG0fGjMGs44HuMD2nomQJT19yd48w M7p9jQH0lWhblY8T+9NlOALrKM4/+jsquy4eIaTM18tvBWBG53bGnzAop+dvHG2w7o iXkHuDU1T3USJA6nXrz2jBfWzS301xT7BRyjz81QaZwmMkp5slxYKpzUUi4jKwD1Oc tVUTTebjHZYqVYVUozHJ4pV3R/Ap/qGE/ml2ybDn2FNBOv1m19Xk1Z00hiGe+hQquS /tm4oPFd0zZf33u+wg9JvV44xtTiGSD8pivXYPQEyE3fGg0LhxVG0meTPzaTS5aPA8 rp9Z2ZvumKPWg== Date: Thu, 30 Sep 2021 10:53:36 +0300 From: Leon Romanovsky To: Jinpu Wang Cc: Jack Wang , Md Haris Iqbal , RDMA mailing list , Bart Van Assche , Doug Ledford , Jason Gunthorpe , Gioh Kim , Aleksei Marov Subject: Re: [PATCH for-next 6/7] RDMA/rtrs: Do not allow sessname to contain special symbols / and . Message-ID: References: <20210922125333.351454-1-haris.iqbal@ionos.com> <20210922125333.351454-7-haris.iqbal@ionos.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Sep 30, 2021 at 09:10:33AM +0200, Jinpu Wang wrote: > On Thu, Sep 30, 2021 at 9:01 AM Leon Romanovsky wrote: > > > > On Thu, Sep 30, 2021 at 08:03:40AM +0200, Jinpu Wang wrote: > > > On Wed, Sep 29, 2021 at 2:04 PM Leon Romanovsky wrote: > > > > > > > > On Wed, Sep 29, 2021 at 09:00:56AM +0200, Jack Wang wrote: > > > > > Leon Romanovsky 于2021年9月28日周二 上午9:28写道： > > > > > > > > > > > > On Tue, Sep 28, 2021 at 09:08:26AM +0200, Jack Wang wrote: > > > > > > > Leon Romanovsky 于2021年9月27日周一 下午2:23写道： > > > > > > > > > > > > > > > > On Wed, Sep 22, 2021 at 02:53:32PM +0200, Md Haris Iqbal wrote: > > > > > > > > > Allowing these characters in sessname can lead to unexpected results, > > > > > > > > > particularly because / is used as a separator between files in a path, > > > > > > > > > and . points to the current directory. > > > > > > > > > > > > > > > > > > Signed-off-by: Md Haris Iqbal > > > > > > > > > Reviewed-by: Gioh Kim > > > > > > > > > Reviewed-by: Aleksei Marov > > > > > > > > > --- > > > > > > > > > drivers/infiniband/ulp/rtrs/rtrs-clt.c | 6 ++++++ > > > > > > > > > drivers/infiniband/ulp/rtrs/rtrs-srv.c | 5 +++++ > > > > > > > > > 2 files changed, 11 insertions(+) > > > > > > > > > > > > > > > > It will be safer if you check for only allowed symbols and disallow > > > > > > > > everything else. Check for: a-Z, 0-9 and "-". > > > > > > > > > > > > > > > Hi Leon, > > > > > > > > > > > > > > Thanks for your suggestions. > > > > > > > The reasons we choose to do disallow only '/' and '.': > > > > > > > 1 more flexible, most UNIX filenames allow any 8-bit set, except '/' and null. > > > > > > > > > > > > So you need to add all possible protections and checks that VFS has to allow "random" name. > > > > > It's only about sysfs here, as we use sessname to create dir in sysfs, > > > > > and I checked the code, it allows any 8-bit set, and convert '/' to > > > > > '!', see https://elixir.bootlin.com/linux/latest/source/lib/kobject.c#L299 > > > > > > > > > > > > > 2 matching for 2 characters is faster than checking all the allowed > > > > > > > symbols during session establishment. > > > > > > > > > > > > Extra CPU cycles won't make any difference here. > > > > > As we can have hundreds of sessions, in the end, it matters. > > > > > > > > Your rtrs_clt_open() function is far from being optimized for > > > > performance. It allocates memory, iterates over all paths, creates > > > > sysfs and kobject. > > > > > > > > So no, it doesn't matter here. > > > > > > > Let me reiterate, why do we want to further slow it down, what do you > > > anticipate if we only do the disallow approach > > > as we do it now? > > > > It is common practice to sanitize user input and explicitly allow known > > good input, instead of relying on deny of bad input. We don't know the > > future and can't be sure that "deny" is actually closed all holes. > > Thanks for the clarification, but still what kind of holes do you have > in mind, the input string length is already checked and it's > not duplicated with other sessname. and sysfs does allow all 8 bit set IIUC. As an example, symbols like "/" and "\". > > Thanks! > > > Thanks