From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751197Ab0BCFMc (ORCPT ); Wed, 3 Feb 2010 00:12:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:23840 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735Ab0BCFM3 (ORCPT ); Wed, 3 Feb 2010 00:12:29 -0500 Message-ID: <4B690681.6070908@redhat.com> Date: Wed, 03 Feb 2010 13:15:45 +0800 From: Cong Wang User-Agent: Thunderbird 2.0.0.23 (X11/20091001) MIME-Version: 1.0 To: Eric Dumazet CC: linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, Neil Horman , linux-sctp@vger.kernel.org, David Miller Subject: Re: [RFC Patch] net: reserve ports for applications using fixed port numbers References: <20100203043332.3817.27932.sendpatchset@localhost.localdomain> <1265171993.3274.3.camel@edumazet-laptop> In-Reply-To: <1265171993.3274.3.camel@edumazet-laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric Dumazet wrote: > Le mardi 02 février 2010 à 23:30 -0500, Amerigo Wang a écrit : >> This patch introduces /proc/sys/net/ipv4/ip_local_reserved_ports, >> it can be used like ip_local_port_range, but this is used to >> reserve ports for third-party applications which use fixed >> port numbers within ip_local_port_range. >> >> This only affects the applications which call socket functions >> like bind(2) with port number 0, to prevent the kernel getting the ports >> within the specified range for them. For applications which use fixed >> port number, it will have no effects. >> >> Any comments are welcome. >> >> Signed-off-by: WANG Cong >> Cc: David Miller >> Cc: Neil Horman >> Cc: Eric Dumazet > >> .procname = "igmp_max_memberships", >> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c >> index f0126fd..83045ca 100644 >> --- a/net/ipv4/udp.c >> +++ b/net/ipv4/udp.c >> @@ -210,8 +210,11 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, >> inet_get_local_port_range(&low, &high); >> remaining = (high - low) + 1; >> >> +again: >> rand = net_random(); >> first = (((u64)rand * remaining) >> 32) + low; >> + if (inet_is_reserved_local_port(first)) >> + goto again; >> /* >> * force rand to be an odd multiple of UDP_HTABLE_SIZE >> */ > > Unless I misread the patch, you are checking only the 'first' port that > udp_lib_get_port() chose. > > I would use inet_get_local_reserved_ports(&min_res, &max_res); > and check every port that we chose in the loop to avoid it if necessary. > Hmm, right, 'first' is used to do iteration, but I did missed 'last'. Thanks! I will fix this in the next update.