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net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute

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IPv6 returns multipath routes as a series of individual routes making
their display and handling by userspace different and more complicated
than IPv4, putting the burden on the user to see that a route is part of
a multipath route and internally creating a multipath route if desired
(e.g., libnl does this as of commit 29b71371e764). This patch addresses
this difference, allowing multipath routes to be returned using the
RTA_MULTIPATH attribute.

The end result is that IPv6 multipath routes can be treated and displayed
in a format similar to IPv4:

    $ ip -6 ro ls vrf red
    2001:db8:1::/120 dev eth1 proto kernel metric 256  pref medium
    2001:db8:2::/120 dev eth2 proto kernel metric 256  pref medium
    2001:db8:200::/120 metric 1024
	    nexthop via 2001:db8:1::2  dev eth1 weight 1
	    nexthop via 2001:db8:2::2  dev eth2 weight 1

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ahern 2017-02-02 12:37:09 -08:00 committed by David S. Miller
parent 0ae8133586
commit beb1afac51
2 changed files with 105 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
net/ipv6/ip6_fib.c
View File

@ -318,6 +318,16 @@ static int fib6_dump_node(struct fib6_walker *w)
w->leaf = rt;
return 1;
}
/* Multipath routes are dumped in one route with the
* RTA_MULTIPATH attribute. Jump 'rt' to point to the
* last sibling of this route (no need to dump the
* sibling routes again)
*/
if (rt->rt6i_nsiblings)
rt = list_last_entry(&rt->rt6i_siblings,
struct rt6_info,
rt6i_siblings);
}
w->leaf = NULL;
return 0;

112
net/ipv6/route.c
View File

@ -3195,8 +3195,20 @@ static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh)
return ip6_route_add(&cfg);
}
static inline size_t rt6_nlmsg_size(struct rt6_info *rt)
static size_t rt6_nlmsg_size(struct rt6_info *rt)
{
int nexthop_len = 0;
if (rt->rt6i_nsiblings) {
nexthop_len = nla_total_size(0) /* RTA_MULTIPATH */
+ NLA_ALIGN(sizeof(struct rtnexthop))
+ nla_total_size(16) /* RTA_GATEWAY */
+ nla_total_size(4) /* RTA_OIF */
+ lwtunnel_get_encap_size(rt->dst.lwtstate);
nexthop_len *= rt->rt6i_nsiblings;
}
return NLMSG_ALIGN(sizeof(struct rtmsg))
+ nla_total_size(16) /* RTA_SRC */
+ nla_total_size(16) /* RTA_DST */
@ -3210,7 +3222,62 @@ static inline size_t rt6_nlmsg_size(struct rt6_info *rt)
+ nla_total_size(sizeof(struct rta_cacheinfo))
+ nla_total_size(TCP_CA_NAME_MAX) /* RTAX_CC_ALGO */
+ nla_total_size(1) /* RTA_PREF */
+ lwtunnel_get_encap_size(rt->dst.lwtstate);
+ lwtunnel_get_encap_size(rt->dst.lwtstate)
+ nexthop_len;
}
static int rt6_nexthop_info(struct sk_buff *skb, struct rt6_info *rt,
unsigned int *flags)
{
if (!netif_running(rt->dst.dev) || !netif_carrier_ok(rt->dst.dev)) {
*flags |= RTNH_F_LINKDOWN;
if (rt->rt6i_idev->cnf.ignore_routes_with_linkdown)
*flags |= RTNH_F_DEAD;
}
if (rt->rt6i_flags & RTF_GATEWAY) {
if (nla_put_in6_addr(skb, RTA_GATEWAY, &rt->rt6i_gateway) < 0)
goto nla_put_failure;
}
if (rt->dst.dev &&
nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
goto nla_put_failure;
if (rt->dst.lwtstate &&
lwtunnel_fill_encap(skb, rt->dst.lwtstate) < 0)
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
static int rt6_add_nexthop(struct sk_buff *skb, struct rt6_info *rt)
{
struct rtnexthop *rtnh;
unsigned int flags = 0;
rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
if (!rtnh)
goto nla_put_failure;
rtnh->rtnh_hops = 0;
rtnh->rtnh_ifindex = rt->dst.dev ? rt->dst.dev->ifindex : 0;
if (rt6_nexthop_info(skb, rt, &flags) < 0)
goto nla_put_failure;
rtnh->rtnh_flags = flags;
/* length of rtnetlink header + attributes */
rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
static int rt6_fill_node(struct net *net,
@ -3264,11 +3331,6 @@ static int rt6_fill_node(struct net *net,
else
rtm->rtm_type = RTN_UNICAST;
rtm->rtm_flags = 0;
if (!netif_running(rt->dst.dev) || !netif_carrier_ok(rt->dst.dev)) {
rtm->rtm_flags |= RTNH_F_LINKDOWN;
if (rt->rt6i_idev->cnf.ignore_routes_with_linkdown)
rtm->rtm_flags |= RTNH_F_DEAD;
}
rtm->rtm_scope = RT_SCOPE_UNIVERSE;
rtm->rtm_protocol = rt->rt6i_protocol;
if (rt->rt6i_flags & RTF_DYNAMIC)
@ -3332,17 +3394,35 @@ static int rt6_fill_node(struct net *net,
if (rtnetlink_put_metrics(skb, metrics) < 0)
goto nla_put_failure;
if (rt->rt6i_flags & RTF_GATEWAY) {
if (nla_put_in6_addr(skb, RTA_GATEWAY, &rt->rt6i_gateway) < 0)
goto nla_put_failure;
}
if (rt->dst.dev &&
nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
goto nla_put_failure;
if (nla_put_u32(skb, RTA_PRIORITY, rt->rt6i_metric))
goto nla_put_failure;
/* For multipath routes, walk the siblings list and add
* each as a nexthop within RTA_MULTIPATH.
*/
if (rt->rt6i_nsiblings) {
struct rt6_info *sibling, *next_sibling;
struct nlattr *mp;
mp = nla_nest_start(skb, RTA_MULTIPATH);
if (!mp)
goto nla_put_failure;
if (rt6_add_nexthop(skb, rt) < 0)
goto nla_put_failure;
list_for_each_entry_safe(sibling, next_sibling,
&rt->rt6i_siblings, rt6i_siblings) {
if (rt6_add_nexthop(skb, sibling) < 0)
goto nla_put_failure;
}
nla_nest_end(skb, mp);
} else {
if (rt6_nexthop_info(skb, rt, &rtm->rtm_flags) < 0)
goto nla_put_failure;
}
expires = (rt->rt6i_flags & RTF_EXPIRES) ? rt->dst.expires - jiffies : 0;
if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0)
@ -3351,8 +3431,6 @@ static int rt6_fill_node(struct net *net,
if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt->rt6i_flags)))
goto nla_put_failure;
if (lwtunnel_fill_encap(skb, rt->dst.lwtstate) < 0)
goto nla_put_failure;
nlmsg_end(skb, nlh);
return 0;