On Mon, Nov 26, 2012 at 09:54:14AM +0900, Kohji Okuno wrote:
> Hi,
>
> Would someone check the following code?
>
> If the hardware do not process an 802.1Q tag, the kernel repacks mbuf
> in line 578-580. But, `struct ether_header *eh' was assigned at line 484.
>
> And, in line 611-637, because of the kernel refers old eh pointer, the
> kernel will misjudges its ether packet.
>
> I think that `eh = mtod(m, struct ether_header *);' is needed after
> line 580.
Yes, your analysis looks correct.
>
> Thanks,
> Kohji Okuno
>
> sys/net/if_ethersubr.c:
> 448 static void
> 449 ether_input_internal(struct ifnet *ifp, struct mbuf *m)
> 450 {
> 451 struct ether_header *eh;
>
> 484 eh = mtod(m, struct ether_header *);
>
> 554 /*
> 555 * If the hardware did not process an 802.1Q tag, do this now,
> 556 * to allow 802.1P priority frames to be passed to the main
> input
> 557 * path correctly.
> 558 * TODO: Deal with Q-in-Q frames, but not arbitrary nesting
> levels.
> 559 */
> 560 if ((m->m_flags & M_VLANTAG) == 0 && etype == ETHERTYPE_VLAN) {
>
> 578 bcopy((char *)evl, (char *)evl + ETHER_VLAN_ENCAP_LEN,
> 579 ETHER_HDR_LEN - ETHER_TYPE_LEN);
> 580 m_adj(m, ETHER_VLAN_ENCAP_LEN);
> 581 }
>
> 610
> 611 #if defined(INET) || defined(INET6)
> 612 /*
> 613 * Clear M_PROMISC on frame so that carp(4) will see it when the
> 614 * mbuf flows up to Layer 3.
> 615 * FreeBSD's implementation of carp(4) uses the inprotosw
> 616 * to dispatch IPPROTO_CARP. carp(4) also allocates its own
> 617 * Ethernet addresses of the form 00:00:5e:00:01:xx, which
> 618 * is outside the scope of the M_PROMISC test below.
> 619 * TODO: Maintain a hash table of ethernet addresses other than
> 620 * ether_dhost which may be active on this ifp.
> 621 */
> 622 if (ifp->if_carp && (*carp_forus_p)(ifp, eh->ether_dhost)) {
> 623 m->m_flags &= ~M_PROMISC;
> 624 } else
> 625 #endif
> 626 {
> 627 /*
> 628 * If the frame received was not for our MAC address,
> set the
> 629 * M_PROMISC flag on the mbuf chain. The frame may need
> to
> 630 * be seen by the rest of the Ethernet input path in
> case of
> 631 * re-entry (e.g. bridge, vlan, netgraph) but should
> not be
> 632 * seen by upper protocol layers.
> 633 */
> 634 if (!ETHER_IS_MULTICAST(eh->ether_dhost) &&
> 635 bcmp(IF_LLADDR(ifp), eh->ether_dhost,
> ETHER_ADDR_LEN) != 0)
> 636 m->m_flags |= M_PROMISC;
> 637 }
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