Re: IPV6_PKTINFO seems not to be honored correctly by RAW-sockets
From: Steven Barth <hidden>
Date: 2012-10-30 16:52:41
Thanks for your quick reply. I just saw that there is also a IPV6_PKTINFO setsockopt-option which was probably what your patch affects. However what I actually meant was the IPV6_PKTINFO control message for sendmsg. Sorry for being ambiguous here. I tried to trace the bug down a bit further with my unfortunately very limited kernel debugging skills. It seems that the destined interface is correctly set in fl6->flowi6_oif also still when it reaches ip6_push_pending_frames in ip6_output.c so I guess it must be lost some time later but I couldn't find out exactly where yet. I'll try to find more information later if I can find some free time. Regards, Steven On 30.10.2012 11:42, Eric Dumazet wrote:
quoted hunk ↗ jump to hunk
From: Eric Dumazet <edumazet@google.com> On Tue, 2012-10-30 at 09:58 +0100, Steven Barth wrote:quoted
Hi, I recently noticed that there might be an unexpected behavior in the handling of IPV6_PKTINFO for RAW-sockets. It seems that the given destination interface is ignored. I just reproduced this on 3.7.0-rc3 vanilla but some quick tests with 2.6.32 and 3.5 distro-kernels on different machines showed the same. I've noticed this first in my own software but I could also reproduce it easily with standard tools like ping6 from iputils: Have 2 network interfaces with (global) IPv6-addresses assigned (e.g. eth0 with fd00::1/64 and eth1 with fd01::1/64) and do a ping6 -I eth1 fd00::1 (ping6 from iputils uses IPV6_PKTINFO internally). For me the result was that even though I set the interface to eth1 the ECHO was still send to eth0. Also (although probably unrelated) forwarding for IPv6 was disabled. If I try something similar with IPv4 and ping -I ... the ECHO doesn't go out on eth0 but - as expected - on eth1. However if I use traceroute(6) with -I (ICMP-traceroute) and the -i option to determine the interface, packages seem to be sent through the expected interface. Internally it seems that traceroute(6) uses SO_BINDTODEVICE instead of IP(V6)_PKTINFO which seems to work. So it seems there might be something wrong with IPV6_PKTINFO or is this expected behavior?I believe its not expected behavior. Is the following patch fixing it ? Thanks [PATCH] ipv6: raw: honor IPV6_PKTINFO Let ping6 -I interface works correctly. If socket was not bound to a given interface, check if IPV6_PKTINFO was issued on this socket. Reported-by: Steven Barth <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> ---diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index d8e95c7..363ee65 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c@@ -814,8 +814,8 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk, fl6.flowlabel = np->flow_label; } - if (fl6.flowi6_oif == 0) - fl6.flowi6_oif = sk->sk_bound_dev_if; + if (!fl6.flowi6_oif) + fl6.flowi6_oif = sk->sk_bound_dev_if ?: np->sticky_pktinfo.ipi6_ifindex; if (msg->msg_controllen) { opt = &opt_space;