From: Shan Wei <shanwei@cn•fujitsu.com>
To: "David Miller" <davem@davemloft•net>,
"yoshfuji@linux-ipv6•org >> YOSHIFUJI Hideaki"
<yoshfuji@linux-ipv6•org>, 魏勇军 <yjwei@cn•fujitsu.com>,
vladislav.yasevich@hp•com
Cc: kuznet@ms2•inr.ac.ru, pekkas@netcore•fi, jmorris@namei•org,
Patrick McHardy <kaber@trash•net>,
eric.dumazet@gmail•com, Shan Wei <shanwei@cn•fujitsu.com>,
sri@us•ibm.com, Herbert Xu <herbert@gondor•apana.org.au>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
linux-sctp@vger•kernel.org
Subject: [PATCH BUG-FIX] ipv6: allow to send packet after receiving ICMPv6 Too Big message with MTU field less than IPV6_MIN_MTU
Date: Mon, 19 Apr 2010 10:58:22 +0800 [thread overview]
Message-ID: <4BCBC6CE.9020302@cn.fujitsu.com> (raw)
According to RFC2460, PMTU is set to the IPv6 Minimum Link
MTU (1280) and a fragment header should always be included
after a node receiving Too Big message reporting PMTU is
less than the IPv6 Minimum Link MTU.
After receiving a ICMPv6 Too Big message reporting PMTU is
less than the IPv6 Minimum Link MTU, sctp *can't* send any
data/control chunk that total length including IPv6 head
and IPv6 extend head is less than IPV6_MIN_MTU(1280 bytes).
The failure occured in p6_fragment(), about reason
see following(take SHUTDOWN chunk for example):
sctp_packet_transmit (SHUTDOWN chunk, len=16 byte)
|------sctp_v6_xmit (local_df=0)
|------ip6_xmit
|------ip6_output (dst_allfrag is ture)
|------ip6_fragment
In ip6_fragment(), for local_df=0, drops the the packet
and returns EMSGSIZE.
The patch fixes it with adding check length of skb->len.
In this case, Ipv6 not to fragment upper protocol data,
just only add a fragment header before it.
Signed-off-by: Shan Wei <shanwei@cn•fujitsu.com>
---
net/ipv6/ip6_output.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 5129a16..c3edb6c 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -625,7 +625,7 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
/* We must not fragment if the socket is set to force MTU discovery
* or if the skb it not generated by a local socket.
*/
- if (!skb->local_df) {
+ if (!skb->local_df && skb->len > mtu) {
skb->dev = skb_dst(skb)->dev;
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
--
1.6.3.3
next reply other threads:[~2010-04-19 3:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-19 2:58 Shan Wei [this message]
2010-04-19 3:55 ` [PATCH BUG-FIX] ipv6: allow to send packet after receiving ICMPv6 Too Big message with MTU field less than IPV6_MIN_MTU Herbert Xu
2010-04-19 6:49 ` Shan Wei
2010-04-22 5:48 ` David Miller
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