ipv6: export function to send route updates

Add fib6_rt_update to send RTM_NEWROUTE with NLM_F_REPLACE set. This
helper will be used by the nexthop code to notify userspace of routes
that are impacted when a nexthop config is updated via replace.

This notification is needed for legacy apps that do not understand
the new nexthop object. Apps that are nexthop aware can use the
RTA_NH_ID attribute in the route notification to just ignore it.

In the future this should be wrapped in a sysctl to allow OS'es that
are fully updated to avoid the notificaton storm.

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

1 files changed, 32 insertions, 0 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7a014ca877ed..c52a7f49d096 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5123,6 +5123,38 @@ errout:
                 rtnl_set_sk_err(net, RTNLGRP_IPV6_ROUTE, err);
 }
 
+void fib6_rt_update(struct net *net, struct fib6_info *rt,
+                    struct nl_info *info)
+{
+        u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
+        struct sk_buff *skb;
+        int err = -ENOBUFS;
+
+        /* call_fib6_entry_notifiers will be removed when in-kernel notifier
+         * is implemented and supported for nexthop objects
+         */
+        call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_REPLACE, rt, NULL);
+
+        skb = nlmsg_new(rt6_nlmsg_size(rt), gfp_any());
+        if (!skb)
+                goto errout;
+
+        err = rt6_fill_node(net, skb, rt, NULL, NULL, NULL, 0,
+                            RTM_NEWROUTE, info->portid, seq, NLM_F_REPLACE);
+        if (err < 0) {
+                /* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
+                WARN_ON(err == -EMSGSIZE);
+                kfree_skb(skb);
+                goto errout;
+        }
+        rtnl_notify(skb, net, info->portid, RTNLGRP_IPV6_ROUTE,
+                    info->nlh, gfp_any());
+        return;
+errout:
+        if (err < 0)
+                rtnl_set_sk_err(net, RTNLGRP_IPV6_ROUTE, err);
+}
+
 static int ip6_route_dev_notify(struct notifier_block *this,
                                 unsigned long event, void *ptr)
 {