From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753433AbbL2Osw (ORCPT ); Tue, 29 Dec 2015 09:48:52 -0500 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:44576 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752695AbbL2Ost (ORCPT ); Tue, 29 Dec 2015 09:48:49 -0500 X-Sasl-enc: q5TEbGVuGrIXtFVSF+/atjYORmZ5zMbt64tUgfw7r/rx 1451400528 Subject: Re: [PATCH] unix: properly account for FDs passed over unix sockets To: Willy Tarreau , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20151228141435.GA13351@1wt.eu> Cc: Linus Torvalds , Eric Dumazet , socketpair@gmail.com From: Hannes Frederic Sowa Message-ID: <56829D4D.4090109@stressinduktion.org> Date: Tue, 29 Dec 2015 15:48:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <20151228141435.GA13351@1wt.eu> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28.12.2015 15:14, Willy Tarreau wrote: > It is possible for a process to allocate and accumulate far more FDs than > the process' limit by sending them over a unix socket then closing them > to keep the process' fd count low. > > This change addresses this problem by keeping track of the number of FDs > in flight per user and preventing non-privileged processes from having > more FDs in flight than their configured FD limit. > > Reported-by: socketpair@gmail.com > Suggested-by: Linus Torvalds > Signed-off-by: Willy Tarreau Thanks for the patch! I think this does not close the DoS attack completely as we duplicate fds if the reader uses MSG_PEEK on the unix domain socket and thus clones the fd. Have I overlooked something? Thanks, Hannes