From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH iptables] iptables: use IPC semaphore instead of abstract unix sockets Date: Mon, 19 Jan 2015 13:24:10 +0100 Message-ID: <20150119122410.GA4206@salvia> References: <1421615616-23053-1-git-send-email-pablo@netfilter.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org, kernel@linuxace.com, lennart@poettering.net To: Jan Engelhardt Return-path: Received: from mail.us.es ([193.147.175.20]:42097 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751873AbbASMVW (ORCPT ); Mon, 19 Jan 2015 07:21:22 -0500 Content-Disposition: inline In-Reply-To: Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Sun, Jan 18, 2015 at 10:28:32PM +0100, Jan Engelhardt wrote: > On Sunday 2015-01-18 22:13, Pablo Neira Ayuso wrote: > > >This patch introduces a semaphore > >index b18022e..80eed2c 100644 > >--- a/iptables/xshared.c > >+++ b/iptables/xshared.c > >+static int xtables_check_owner(int semid) > >+{ > >+ int ret; > >+ struct semid_ds ds; > >+ > >+ ret = semctl(semid, 0, IPC_STAT, &ds); > > Is there a particular reason you are not using the POSIX semaphores? > [sem_open/shm_open as per sem_overview(7)]. Please, read the patch description: "This patch introduces a semaphore that is identified by the path to the iptables binary, it also relies on SEM_UNDO so the kernel performs the up() operation at process exit to avoid races with signals. This also avoids file locks that require a writable filesystem."