Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755173AbaFCLyz (ORCPT ); Tue, 3 Jun 2014 07:54:55 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:43742 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932872AbaFCLmY (ORCPT ); Tue, 3 Jun 2014 07:42:24 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , "David S. Miller" , Luis Henriques Subject: [PATCH 3.11 101/138] ipv6: Limit mtu to 65575 bytes Date: Tue, 3 Jun 2014 12:39:07 +0100 Message-Id: <1401795584-22664-102-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1401795584-22664-1-git-send-email-luis.henriques@canonical.com> References: <1401795584-22664-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 30f78d8ebf7f514801e71b88a10c948275168518 upstream. Francois reported that setting big mtu on loopback device could prevent tcp sessions making progress. We do not support (yet ?) IPv6 Jumbograms and cook corrupted packets. We must limit the IPv6 MTU to (65535 + 40) bytes in theory. Tested: ifconfig lo mtu 70000 netperf -H ::1 Before patch : Throughput : 0.05 Mbits After patch : Throughput : 35484 Mbits Reported-by: Francois WELLENREITER Signed-off-by: Eric Dumazet Acked-by: YOSHIFUJI Hideaki Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- include/net/ip6_route.h | 5 +++++ net/ipv6/route.c | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index c7b8860f29fd..e20e7134e0e9 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -32,6 +32,11 @@ struct route_info { #define RT6_LOOKUP_F_SRCPREF_PUBLIC 0x00000010 #define RT6_LOOKUP_F_SRCPREF_COA 0x00000020 +/* We do not (yet ?) support IPv6 jumbograms (RFC 2675) + * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header + */ +#define IP6_MAX_MTU (0xFFFF + sizeof(struct ipv6hdr)) + /* * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate * between IPV6_ADDR_PREFERENCES socket option values diff --git a/net/ipv6/route.c b/net/ipv6/route.c index bf7a99fe4826..f52f3fa5c894 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1261,7 +1261,7 @@ static unsigned int ip6_mtu(const struct dst_entry *dst) unsigned int mtu = dst_metric_raw(dst, RTAX_MTU); if (mtu) - return mtu; + goto out; mtu = IPV6_MIN_MTU; @@ -1271,7 +1271,8 @@ static unsigned int ip6_mtu(const struct dst_entry *dst) mtu = idev->cnf.mtu6; rcu_read_unlock(); - return mtu; +out: + return min_t(unsigned int, mtu, IP6_MAX_MTU); } static struct dst_entry *icmp6_dst_gc_list; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/