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

[Ben Cox]

Nice!

That works in my head at least, Sorry about not seeing that fairly
glaring memory issue there.

Are you sure " skb->transport_header += iphlen; " won't have a knock
on affect when it's given to NF_HOOK ( as in, would a potential
userspace program get something it does not expect anymore ) ?

How does submission work at this point if the above is not a issue
(apologies if this is already in a FAQ somewhere I missed)?

On Mon, Oct 12, 2015 at 12:09 AM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> On Sun, 2015-10-11 at 15:44 -0700, Eric Dumazet wrote:
>> On Sun, 2015-10-11 at 15:43 -0700, Eric Dumazet wrote:
>>
>> > But your code reads 21th byte.
>>
>> BTW, nice catch !
>
> Maybe the following one.
>
> 1) We properly set transport header
> 2) We use icmp_hdr() helper.
>
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 561cd4b8fc6e..ffe25cd1f0e0 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -406,11 +406,11 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
>                         ip_select_ident(net, skb, NULL);
>
>                 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
> +               skb->transport_header += iphlen;
> +               if (iph->protocol == IPPROTO_ICMP &&
> +                   length >= iphlen + sizeof(struct icmphdr))
> +                       icmp_out_count(net, icmp_hdr(skb)->type);
>         }
> -       if (iph->protocol == IPPROTO_ICMP)
> -               icmp_out_count(net, ((struct icmphdr *)
> -                       skb_transport_header(skb))->type);
> -
>         err = NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_OUT, sk, skb,
>                       NULL, rt->dst.dev, dst_output_sk);
>         if (err > 0)
>
>
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