Commit 58acfd71 authored Dec 20, 2017 by Ido Schimmel Committed by David S. Miller Dec 21, 2017

ipv6: Honor specified parameters in fibmatch lookup



Currently, parameters such as oif and source address are not taken into
account during fibmatch lookup. Example (IPv4 for reference) before
patch:

$ ip -4 route show
192.0.2.0/24 dev dummy0 proto kernel scope link src 192.0.2.1
198.51.100.0/24 dev dummy1 proto kernel scope link src 198.51.100.1

$ ip -6 route show
2001:db8:1::/64 dev dummy0 proto kernel metric 256 pref medium
2001:db8:2::/64 dev dummy1 proto kernel metric 256 pref medium
fe80::/64 dev dummy0 proto kernel metric 256 pref medium
fe80::/64 dev dummy1 proto kernel metric 256 pref medium

$ ip -4 route get fibmatch 192.0.2.2 oif dummy0
192.0.2.0/24 dev dummy0 proto kernel scope link src 192.0.2.1
$ ip -4 route get fibmatch 192.0.2.2 oif dummy1
RTNETLINK answers: No route to host

$ ip -6 route get fibmatch 2001:db8:1::2 oif dummy0
2001:db8:1::/64 dev dummy0 proto kernel metric 256 pref medium
$ ip -6 route get fibmatch 2001:db8:1::2 oif dummy1
2001:db8:1::/64 dev dummy0 proto kernel metric 256 pref medium

After:

$ ip -6 route get fibmatch 2001:db8:1::2 oif dummy0
2001:db8:1::/64 dev dummy0 proto kernel metric 256 pref medium
$ ip -6 route get fibmatch 2001:db8:1::2 oif dummy1
RTNETLINK answers: Network is unreachable

The problem stems from the fact that the necessary route lookup flags
are not set based on these parameters.

Instead of duplicating the same logic for fibmatch, we can simply
resolve the original route from its copy and dump it instead.

Fixes: 18c3a61c ("net: ipv6: RTM_GETROUTE: return matched fib result when requested")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8b6ca2bf

net/ipv6/route.c

+11 −8

Original line number	Original line	Diff line number	Diff line
	@@ -4298,19 +4298,13 @@ static int inet6_rtm_getroute(struct sk_buff in_skb, struct nlmsghdr nlh,
	if (!ipv6_addr_any(&fl6.saddr))		if (!ipv6_addr_any(&fl6.saddr))
	flags \|= RT6_LOOKUP_F_HAS_SADDR;		flags \|= RT6_LOOKUP_F_HAS_SADDR;

	if (!fibmatch)
	dst = ip6_route_input_lookup(net, dev, &fl6, flags);		dst = ip6_route_input_lookup(net, dev, &fl6, flags);
	else
	dst = ip6_route_lookup(net, &fl6, 0);

	rcu_read_unlock();		rcu_read_unlock();
	} else {		} else {
	fl6.flowi6_oif = oif;		fl6.flowi6_oif = oif;

	if (!fibmatch)
	dst = ip6_route_output(net, NULL, &fl6);		dst = ip6_route_output(net, NULL, &fl6);
	else
	dst = ip6_route_lookup(net, &fl6, 0);
	}		}


	@@ -4327,6 +4321,15 @@ static int inet6_rtm_getroute(struct sk_buff in_skb, struct nlmsghdr nlh,
	goto errout;		goto errout;
	}		}

			if (fibmatch && rt->dst.from) {
			struct rt6_info *ort = container_of(rt->dst.from,
			struct rt6_info, dst);

			dst_hold(&ort->dst);
			ip6_rt_put(rt);
			rt = ort;
			}

	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);		skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
	if (!skb) {		if (!skb) {
	ip6_rt_put(rt);		ip6_rt_put(rt);