Commit 8c14586f authored Apr 24, 2016 by David Ahern Committed by David S. Miller Apr 27, 2016

net: ipv6: Use passed in table for nexthop lookups



Similar to 3bfd8472 ("net: Use passed in table for nexthop lookups")
for IPv4, if the route spec contains a table id use that to lookup the
next hop first and fall back to a full lookup if it fails (per the fix
4c9bcd11 ("net: Fix nexthop lookups")).

Example:

    root@kenny:~# ip -6 ro ls table red
    local 2100:1::1 dev lo  proto none  metric 0  pref medium
    2100:1::/120 dev eth1  proto kernel  metric 256  pref medium
    local 2100:2::1 dev lo  proto none  metric 0  pref medium
    2100:2::/120 dev eth2  proto kernel  metric 256  pref medium
    local fe80::e0:f9ff:fe09:3cac dev lo  proto none  metric 0  pref medium
    local fe80::e0:f9ff:fe1c:b974 dev lo  proto none  metric 0  pref medium
    fe80::/64 dev eth1  proto kernel  metric 256  pref medium
    fe80::/64 dev eth2  proto kernel  metric 256  pref medium
    ff00::/8 dev red  metric 256  pref medium
    ff00::/8 dev eth1  metric 256  pref medium
    ff00::/8 dev eth2  metric 256  pref medium
    unreachable default dev lo  metric 240  error -113 pref medium

    root@kenny:~# ip -6 ro add table red 2100:3::/64 via 2100:1::64
    RTNETLINK answers: No route to host

Route add fails even though 2100:1::64 is a reachable next hop:
    root@kenny:~# ping6 -I red  2100:1::64
    ping6: Warning: source address might be selected on device other than red.
    PING 2100:1::64(2100:1::64) from 2100:1::1 red: 56 data bytes
    64 bytes from 2100:1::64: icmp_seq=1 ttl=64 time=1.33 ms

With this patch:
    root@kenny:~# ip -6 ro add table red 2100:3::/64 via 2100:1::64
    root@kenny:~# ip -6 ro ls table red
    local 2100:1::1 dev lo  proto none  metric 0  pref medium
    2100:1::/120 dev eth1  proto kernel  metric 256  pref medium
    local 2100:2::1 dev lo  proto none  metric 0  pref medium
    2100:2::/120 dev eth2  proto kernel  metric 256  pref medium
    2100:3::/64 via 2100:1::64 dev eth1  metric 1024  pref medium
    local fe80::e0:f9ff:fe09:3cac dev lo  proto none  metric 0  pref medium
    local fe80::e0:f9ff:fe1c:b974 dev lo  proto none  metric 0  pref medium
    fe80::/64 dev eth1  proto kernel  metric 256  pref medium
    fe80::/64 dev eth2  proto kernel  metric 256  pref medium
    ff00::/8 dev red  metric 256  pref medium
    ff00::/8 dev eth1  metric 256  pref medium
    ff00::/8 dev eth2  metric 256  pref medium
    unreachable default dev lo  metric 240  error -113 pref medium

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 570d8e93

net/ipv6/route.c

+38 −2

Original line number	Diff line number	Diff line
		@@ -1769,6 +1769,37 @@ static int ip6_convert_metrics(struct mx6_config *mxc,
		return -EINVAL;
		}

		static struct rt6_info ip6_nh_lookup_table(struct net net,
		struct fib6_config *cfg,
		const struct in6_addr *gw_addr)
		{
		struct flowi6 fl6 = {
		.flowi6_oif = cfg->fc_ifindex,
		.daddr = *gw_addr,
		.saddr = cfg->fc_prefsrc,
		};
		struct fib6_table *table;
		struct rt6_info *rt;
		int flags = 0;

		table = fib6_get_table(net, cfg->fc_table);
		if (!table)
		return NULL;

		if (!ipv6_addr_any(&cfg->fc_prefsrc))
		flags \|= RT6_LOOKUP_F_HAS_SADDR;

		rt = ip6_pol_route(net, table, cfg->fc_ifindex, &fl6, flags);

		/* if table lookup failed, fall back to full lookup */
		if (rt == net->ipv6.ip6_null_entry) {
		ip6_rt_put(rt);
		rt = NULL;
		}

		return rt;
		}

		static struct rt6_info ip6_route_info_create(struct fib6_config cfg)
		{
		struct net *net = cfg->fc_nlinfo.nl_net;
		@@ -1940,7 +1971,7 @@ static struct rt6_info ip6_route_info_create(struct fib6_config cfg)
		rt->rt6i_gateway = *gw_addr;

		if (gwa_type != (IPV6_ADDR_LINKLOCAL\|IPV6_ADDR_UNICAST)) {
		struct rt6_info *grt;
		struct rt6_info *grt = NULL;

		/* IPv6 strictly inhibits using not link-local
		addresses as nexthop address.
		@@ -1952,7 +1983,12 @@ static struct rt6_info ip6_route_info_create(struct fib6_config cfg)
		if (!(gwa_type & IPV6_ADDR_UNICAST))
		goto out;

		grt = rt6_lookup(net, gw_addr, NULL, cfg->fc_ifindex, 1);
		if (cfg->fc_table)
		grt = ip6_nh_lookup_table(net, cfg, gw_addr);

		if (!grt)
		grt = rt6_lookup(net, gw_addr, NULL,
		cfg->fc_ifindex, 1);

		err = -EHOSTUNREACH;
		if (!grt)

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