This is a note to let you know that I've just added the patch titled
ipv6: Limit mtu to 65575 bytes
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-limit-mtu-to-65575-bytes.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed May 28 20:24:34 PDT 2014
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu, 10 Apr 2014 21:23:36 -0700
Subject: ipv6: Limit mtu to 65575 bytes
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 30f78d8ebf7f514801e71b88a10c948275168518 ]
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 <f.wellenreiter@xxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@xxxxxxxxxxxxxx>
Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/ip6_route.h | 5 +++++
net/ipv6/route.c | 5 +++--
2 files changed, 8 insertions(+), 2 deletions(-)
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -34,6 +34,11 @@ 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
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1092,7 +1092,7 @@ static unsigned int ip6_mtu(const struct
unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
if (mtu)
- return mtu;
+ goto out;
mtu = IPV6_MIN_MTU;
@@ -1102,7 +1102,8 @@ static unsigned int ip6_mtu(const struct
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;
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-3.4/skb-add-inline-helper-for-getting-the-skb-end-offset-from-head.patch
queue-3.4/ipv6-limit-mtu-to-65575-bytes.patch
queue-3.4/tcp_cubic-fix-the-range-of-delayed_ack.patch
queue-3.4/net-gro-reset-skb-truesize-in-napi_reuse_skb.patch
--
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