From b881ef7603230550aa0150b22af94089f07ab00d Mon Sep 17 00:00:00 2001 From: John Heffner Date: Fri, 20 Apr 2007 15:52:39 -0700 Subject: [PATCH] [IPV6]: MTU discovery check in ip6_fragment() Adds a check in ip6_fragment() mirroring ip_fragment() for packets that we can't fragment, and sends an ICMP Packet Too Big message in response. Signed-off-by: John Heffner Signed-off-by: David S. Miller --- net/ipv6/ip6_output.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 4cfdad4e8356..5a5b7d4ad31c 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -567,6 +567,19 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) nexthdr = *prevhdr; mtu = dst_mtu(&rt->u.dst); + + /* We must not fragment if the socket is set to force MTU discovery + * or if the skb it not generated by a local socket. (This last + * check should be redundant, but it's free.) + */ + if (!np || np->pmtudisc >= IPV6_PMTUDISC_DO) { + skb->dev = skb->dst->dev; + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev); + IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS); + kfree_skb(skb); + return -EMSGSIZE; + } + if (np && np->frag_size < mtu) { if (np->frag_size) mtu = np->frag_size; -- 2.30.2