From: Chuck Ebbert <[EMAIL PROTECTED]>
Date: Thu, 26 Apr 2007 18:57:06 -0400
> David Miller wrote:
> >> + case IPV6_SRCRT_TYPE_2:
> >> + if (accept_source_route >= 0)
> >> + break;
> >> + kfree_skb(skb);
> >> + return -1;
> >> + case IPV6_SRCRT_TYPE_0:
> >> + if (accept_source_route > 0)
> >> + break;
> >> + kfree_skb(skb);
> >> + return -1;
> >
> > Yes, that looks like it matches the sysctl documentation more closely:
> >
> > accept_source_route - INTEGER
> > Accept source routing (routing extension header).
> >
> > > 0: Accept routing header.
> > = 0: Accept only routing header type 2.
> > < 0: Do not accept routing header.
> >
> > Type 2 packets should get through as long as the value of the sysctl
> > is not negative.
>
> It was Sergey Vlasov who first found this. I had tried to find his original
> message but I was searching the wrong place.
Actually, earlier in the function accept_source_route is
verified, and if it is negative ipv6_rthdr_rcv() returns
immediately. This is done by the initial code which reads:
if (accept_source_route < 0 ||
((idev = in6_dev_get(skb->dev)) == NULL)) {
kfree_skb(skb);
return -1;
}
if (idev->cnf.accept_source_route < 0) {
in6_dev_put(idev);
kfree_skb(skb);
return -1;
}
then the function proceeds to use the largest of
'accept_source_route' and 'idev->cnf.accept_source_route'
for further checks.
So when we get to the switch statement in question, we know
it will be a positive value, so none of the purely negative
cases need to be considered.
So with Yoshifuji-sans small fix, the switch statement
covers all the cases properly:
switch (hdr->type) {
#ifdef CONFIG_IPV6_MIP6
case IPV6_SRCRT_TYPE_2:
break;
#endif
case IPV6_SRCRT_TYPE_0:
if (accept_source_route > 0)
break;
kfree_skb(skb);
return -1;
default:
IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) -
skb->nh.raw);
return -1;
}
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