At 2016-12-27 15:52:18, "Wei Zhang" <asuka....@163.com> wrote:
>When we send a packet for our own local address on a non-loopback interface
>(e.g. eth0), due to the change had been introduced from commit 0b922b7a829c
>("net: original ingress device index in PKTINFO"), the original ingress
>device index would be set as the loopback interface. However, the packet
>should be considered as if it is being arrived via the sending interface
>(eth0), otherwise it would break the expectation of the userspace
>application (e.g. the DHCPRELEASE message from dhcp_release binary would
>be ignored by the dnsmasq daemon)
>
>Signed-off-by: Wei Zhang <asuka....@163.com>
>---
> net/ipv4/ip_sockglue.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
>diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
>index b8a2d63..b6a6d35 100644
>--- a/net/ipv4/ip_sockglue.c
>+++ b/net/ipv4/ip_sockglue.c
>@@ -1202,8 +1202,13 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct
>sk_buff *skb)
> * which has interface index (iif) as the first member of the
> * underlying inet{6}_skb_parm struct. This code then overlays
> * PKTINFO_SKB_CB and in_pktinfo also has iif as the first
>- * element so the iif is picked up from the prior IPCB
>+ * element so the iif is picked up from the prior IPCB except
>+ * iif is loopback interface which the packet should be
>+ * considered as if it is being arrived via the sending
>interface
> */
>+ if (pktinfo->ipi_ifindex == LOOPBACK_IFINDEX) {
>+ pktinfo->ipi_ifindex = inet_iif(skb);
>+ }
> pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
> } else {
> pktinfo->ipi_ifindex = 0;
>--
>1.8.3.1
>
When I upgrade to the 4.9, the dhcp_release could not release the dhcp
lease, the dnsmasq ignored all the DHCPRELEASE message which it think come
from lo. I think this is due to the commit 0b922b7a829c, which set the
IPCB(skb)->iif = skb->skb_iif in the ip_rcv()!
And I'm very sorry about forgetting checkpatch, I will resend the patch,
hope I'm not bothering you!
Thanks,
Wei Zhang
