From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] ipv4: Fix non-initialized TTL when CONFIG_SYSCTL=n Date: Mon, 23 May 2016 14:33:18 -0700 (PDT) Message-ID: <20160523.143318.293951661657795088.davem@davemloft.net> References: <1463761270-8955-1-git-send-email-ezequiel@vanguardiasur.com.ar> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, kernel@kyup.com, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net To: ezequiel@vanguardiasur.com.ar Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:50517 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbcEWVdU (ORCPT ); Mon, 23 May 2016 17:33:20 -0400 In-Reply-To: <1463761270-8955-1-git-send-email-ezequiel@vanguardiasur.com.ar> Sender: netdev-owner@vger.kernel.org List-ID: From: Ezequiel Garcia Date: Fri, 20 May 2016 13:21:10 -0300 > Commit fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob") > moves the default TTL assignment, and as side-effect IPv4 TTL now > has a default value only if sysctl support is enabled (CONFIG_SYSCTL=y). > > The sysctl_ip_default_ttl is fundamental for IP to work properly, > as it provides the TTL to be used as default. The defautl TTL may be > used in ip_selected_ttl, through the following flow: > > ip_select_ttl > ip4_dst_hoplimit > net->ipv4.sysctl_ip_default_ttl > > This commit fixes the issue by assigning net->ipv4.sysctl_ip_default_ttl > in net_init_net, called during ipv4's initialization. > > Without this commit, a kernel built without sysctl support will send > all IP packets with zero TTL (unless a TTL is explicitly set, e.g. > with setsockopt). > > Given a similar issue might appear on the other knobs that were > namespaceify, this commit also moves them. > > Fixes: fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob") > Signed-off-by: Ezequiel Garcia Applied and queued up for -stable, thanks.