[PATCH] icmp: Fixed bug in raw sockets causing incorrect ICMP SNMP counter values

From: Ben Cartwright-Cox
Date: Sun Oct 11 2015 - 17:31:52 EST


Sending ICMP packets with raw sockets ends up in the SNMP counters
logging the type as the first byte of the IPv4 header rather than
the ICMP header (in nearly all cases this is seen as "OutType69".
This is fixed by adding the IP Header Length to the casting into
a icmphdr struct.

Signed-off-by: Ben Cartwright-Cox <ben@xxxxxxxxxxxxx>
---
net/ipv4/raw.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 561cd4b..1ad8bae 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -409,7 +409,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
}
if (iph->protocol == IPPROTO_ICMP)
icmp_out_count(net, ((struct icmphdr *)
- skb_transport_header(skb))->type);
+ skb_transport_header(skb) + iphlen)->type);

err = NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_OUT, sk, skb,
NULL, rt->dst.dev, dst_output_sk);
--
1.9.1

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