On Tue, Oct 27, 2020 at 5:57 AM Hangbin Liu <liuhang...@gmail.com> wrote:
>
> On Tue, Oct 27, 2020 at 07:57:06AM +0000, Georg Kohmann (geokohma) wrote:
> > > + /* RFC 8200, Section 4.5 Fragment Header:
> > > + * If the first fragment does not include all headers through an
> > > + * Upper-Layer header, then that fragment should be discarded and
> > > + * an ICMP Parameter Problem, Code 3, message should be sent to
> > > + * the source of the fragment, with the Pointer field set to zero.
> > > + */
> > > + nexthdr = hdr->nexthdr;
> > > + offset = ipv6_skip_exthdr(skb, skb_transport_offset(skb), &nexthdr,
> > > &frag_off);
> > > + if (offset >= 0) {
> > > + /* Check some common protocols' header */
> > > + if (nexthdr == IPPROTO_TCP)
> > > + offset += sizeof(struct tcphdr);
> > > + else if (nexthdr == IPPROTO_UDP)
> > > + offset += sizeof(struct udphdr);
> > > + else if (nexthdr == IPPROTO_ICMPV6)
> > > + offset += sizeof(struct icmp6hdr);
> > > + else
> > > + offset += 1;
> > > +
> > > + if (frag_off == htons(ip6_mf) && offset > skb->len) {
> >
> > This do not catch atomic fragments (fragmented packet with only one
> > fragment). frag_off also contains two reserved bits (both 0) that might
> > change in the future.
>
> Thanks, I also didn't aware this scenario.
Sorry, what are atomic fragments?
Do you mean packets with a fragment header that encapsulates the
entire packet? If so, isn't that handled in the branch right above?
("/* It is not a fragmented frame */"). That said, the test based on
IP6_OFFSET LGTM.
