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Date: Thu, 2 Feb 2017 12:37:09 -0800
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: roopa@...ulusnetworks.com, nicolas.dichtel@...nd.com,
David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net-next v4 2/5] net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute
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@...ulusnetworks.com>
---
v4
- reduced this patch to just RT_MULTIPATH encoding
- account for RT_MULTIPATH in rt6_nlmsg_size
v3
- dropped RTM_F_ALL_NEXTHOPS
v2
- changed user api to opt in to new behavior from attribute appended to
the request to requiring an rtmsg struct with the RTM_F_ALL_NEXTHOPS
set
net/ipv6/ip6_fib.c | 10 +++++
net/ipv6/route.c | 112 +++++++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 105 insertions(+), 17 deletions(-)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index febde6c112bf..1bf5e22fb95d 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -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;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 466199cab8cc..8d9970163e33 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3194,8 +3194,20 @@ 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 */
@@ -3209,7 +3221,62 @@ 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,
@@ -3263,11 +3330,6 @@ 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)
@@ -3331,17 +3393,35 @@ 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)
@@ -3350,8 +3430,6 @@ 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;
--
2.1.4
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