From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760529AbXJaP05 (ORCPT ); Wed, 31 Oct 2007 11:26:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759901AbXJaPYf (ORCPT ); Wed, 31 Oct 2007 11:24:35 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:33473 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759673AbXJaPYd (ORCPT ); Wed, 31 Oct 2007 11:24:33 -0400 Date: Wed, 31 Oct 2007 08:11:40 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, bunk@kernel.org, Eric Dumazet , "David S. Miller" Subject: [patch 12/26] : Fix TCP initial sequence number selection. Message-ID: <20071031151140.GM2437@kroah.com> References: <20071031150535.967437651@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="fix-tcp-initial-sequence-number-selection.patch" In-Reply-To: <20071031151015.GA2437@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 2.6.22-stable review patch. If anyone has any objections, please let us know. ------------------ From: Eric Dumazet changeset 162f6690a65075b49f242d3c8cdb5caaa959a060 in mainline. TCP V4 sequence numbers are 32bits, and RFC 793 assumed a 250 KHz clock. In order to follow network speed increase, we can use a faster clock, but we should limit this clock so that the delay between two rollovers is greater than MSL (TCP Maximum Segment Lifetime : 2 minutes) Choosing a 64 nsec clock should be OK, since the rollovers occur every 274 seconds. Problem spotted by Denys Fedoryshchenko [ This bug was introduced by f85958151900f9d30fa5ff941b0ce71eaa45a7de ] Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1550,11 +1550,13 @@ __u32 secure_tcp_sequence_number(__be32 * As close as possible to RFC 793, which * suggests using a 250 kHz clock. * Further reading shows this assumes 2 Mb/s networks. - * For 10 Gb/s Ethernet, a 1 GHz clock is appropriate. - * That's funny, Linux has one built in! Use it! - * (Networks are faster now - should this be increased?) + * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate. + * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but + * we also need to limit the resolution so that the u32 seq + * overlaps less than one time per MSL (2 minutes). + * Choosing a clock of 64 ns period is OK. (period of 274 s) */ - seq += ktime_get_real().tv64; + seq += ktime_get_real().tv64 >> 6; #if 0 printk("init_seq(%lx, %lx, %d, %d) = %d\n", saddr, daddr, sport, dport, seq); --