4.17-stable review patch. If anyone has any objections, please let me know.
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From: Vincent Bernat vincent@bernat.im
commit cede24d1b21d68d84ac5a36c44f7d37daadcc258 upstream.
In commit 47b7e7f82802, this bit was removed at the same time the RT6_LOOKUP_F_IFACE flag was removed. However, it is needed when link-local addresses are used, which is a very common case: when packets are routed, neighbor solicitations are done using link-local addresses. For example, the following neighbor solicitation is not matched by "-m rpfilter":
IP6 fe80::5254:33ff:fe00:1 > ff02::1:ff00:3: ICMP6, neighbor solicitation, who has 2001:db8::5254:33ff:fe00:3, length 32
Commit 47b7e7f82802 doesn't quite explain why we shouldn't use RT6_LOOKUP_F_IFACE in the rpfilter case. I suppose the interface check later in the function would make it redundant. However, the remaining of the routing code is using RT6_LOOKUP_F_IFACE when there is no source address (which matches rpfilter's case with a non-unicast destination, like with neighbor solicitation).
Signed-off-by: Vincent Bernat vincent@bernat.im Fixes: 47b7e7f82802 ("netfilter: don't set F_IFACE on ipv6 fib lookups") Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv6/netfilter/ip6t_rpfilter.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/ipv6/netfilter/ip6t_rpfilter.c +++ b/net/ipv6/netfilter/ip6t_rpfilter.c @@ -48,6 +48,8 @@ static bool rpfilter_lookup_reverse6(str }
fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0; + if ((flags & XT_RPFILTER_LOOSE) == 0) + fl6.flowi6_oif = dev->ifindex;
rt = (void *)ip6_route_lookup(net, &fl6, skb, lookup_flags); if (rt->dst.error)