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::/120 metric 1024
nexthop via 2001:db8:1::62 dev eth1 weight 1
nexthop via 2001:db8:1::61 dev eth1 weight 1
nexthop via 2001:db8:1::60 dev eth1 weight 1
nexthop via 2001:db8:1::59 dev eth1 weight 1
2001:db8:1::/120 dev eth1 proto kernel metric 256 pref medium
...
Suggested-by: Dinesh Dutt <dd...@cumulusnetworks.com>
Signed-off-by: David Ahern <d...@cumulusnetworks.com>
---
v3
- dropped user API to opt-in to change
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
include/net/netlink.h | 1 +
net/ipv6/ip6_fib.c | 16 ++++++-
net/ipv6/route.c | 127 +++++++++++++++++++++++++++++++++++++++++++-------
3 files changed, 126 insertions(+), 18 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index d3938f11ae52..b239fcd33d80 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -229,6 +229,7 @@ struct nl_info {
struct nlmsghdr *nlh;
struct net *nl_net;
u32 portid;
+ bool skip_notify;
};
int netlink_rcv_skb(struct sk_buff *skb,
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index bcaf247232d7..2542794b2c64 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;
}
+
+ /* if multipath routes are dumped in one route with
+ * the RTA_MULTIPATH attribute, then 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;
@@ -871,7 +881,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct
rt6_info *rt,
*ins = rt;
rt->rt6i_node = fn;
atomic_inc(&rt->rt6i_ref);
- inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
+ if (!info->skip_notify)
+ inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
if (!(fn->fn_flags & RTN_RTINFO)) {
@@ -897,7 +908,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct
rt6_info *rt,
rt->rt6i_node = fn;
rt->dst.rt6_next = iter->dst.rt6_next;
atomic_inc(&rt->rt6i_ref);
- inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
+ if (!info->skip_notify)
+ inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
if (!(fn->fn_flags & RTN_RTINFO)) {
info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
fn->fn_flags |= RTN_RTINFO;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 81e2b2a28806..747f333ae006 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3010,19 +3010,25 @@ static int ip6_route_info_append(struct list_head
*rt6_nh_list,
static int ip6_route_multipath_add(struct fib6_config *cfg)
{
+ struct rt6_info *rt, *rt_first = NULL;
struct fib6_config r_cfg;
struct rtnexthop *rtnh;
- struct rt6_info *rt;
struct rt6_nh *err_nh;
struct rt6_nh *nh, *nh_safe;
+ __u16 nlflags;
int remaining;
int attrlen;
int err = 1;
int nhn = 0;
+ int append = cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_APPEND;
int replace = (cfg->fc_nlinfo.nlh &&
(cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_REPLACE));
LIST_HEAD(rt6_nh_list);
+ nlflags = replace ? NLM_F_REPLACE : NLM_F_CREATE;
+ if (append)
+ nlflags |= NLM_F_APPEND;
+
remaining = cfg->fc_mp_len;
rtnh = (struct rtnexthop *)cfg->fc_mp;
@@ -3065,9 +3071,20 @@ static int ip6_route_multipath_add(struct fib6_config
*cfg)
rtnh = rtnh_next(rtnh, &remaining);
}
+ /* for route append want to send separate notifications on
+ * each add; for add and replace send one notification with
+ * all nexthops
+ */
+ if (!append)
+ cfg->fc_nlinfo.skip_notify = 1;
+
err_nh = NULL;
list_for_each_entry(nh, &rt6_nh_list, next) {
err = __ip6_ins_rt(nh->rt6_info, &cfg->fc_nlinfo, &nh->mxc);
+ /* save reference to first route for notification */
+ if (!rt_first && !err && !append)
+ rt_first = nh->rt6_info;
+
/* nh->rt6_info is used or freed at this point, reset to NULL*/
nh->rt6_info = NULL;
if (err) {
@@ -3089,9 +3106,21 @@ static int ip6_route_multipath_add(struct fib6_config
*cfg)
nhn++;
}
+ if (rt_first)
+ inet6_rt_notify(RTM_NEWROUTE, rt_first, &cfg->fc_nlinfo,
+ nlflags);
+
goto cleanup;
add_errout:
+ /* send notification for routes that were added so far so
+ * that the delete notifications sent by ip6_route_del in
+ * the next block are coherent
+ */
+ if (rt_first)
+ inet6_rt_notify(RTM_NEWROUTE, rt_first, &cfg->fc_nlinfo,
+ nlflags);
+
/* Delete routes that were already added */
list_for_each_entry(nh, &rt6_nh_list, next) {
if (err_nh == nh)
@@ -3198,6 +3227,60 @@ static inline size_t rt6_nlmsg_size(struct rt6_info *rt)
+ lwtunnel_get_encap_size(rt->dst.lwtstate);
}
+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,
struct sk_buff *skb, struct rt6_info *rt,
struct in6_addr *dst, struct in6_addr *src,
@@ -3249,11 +3332,6 @@ 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)
@@ -3317,17 +3395,36 @@ 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 this route
+ * is an append, then only send the route that is added.
+ */
+ if (rt->rt6i_nsiblings && !(flags & NLM_F_APPEND)) {
+ 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)
@@ -3336,8 +3433,6 @@ 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
