ipv6: rate-limit probes for neighbourless routes

When commit 270972554c91 ("[IPV6]: ROUTE: Add Router Reachability
Probing (RFC4191).") introduced router probing, the rt6_probe() function
required that a neighbour entry existed. This neighbour entry is used to
record the timestamp of the last probe via the ->updated field.

Later, commit 2152caea7196 ("ipv6: Do not depend on rt->n in rt6_probe().")
removed the requirement for a neighbour entry. Neighbourless routes skip
the interval check and are not rate-limited.

This patch adds rate-limiting for neighbourless routes, by recording the
timestamp of the last probe in the fib6_info itself.

Fixes: 2152caea7196 ("ipv6: Do not depend on rt->n in rt6_probe().")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 3d49305..2d31e22 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -159,6 +159,10 @@ struct fib6_info {
        struct rt6_info * __percpu      *rt6i_pcpu;
        struct rt6_exception_bucket __rcu *rt6i_exception_bucket;
 
+#ifdef CONFIG_IPV6_ROUTER_PREF
+       unsigned long                   last_probe;
+#endif
+
        u32                             fib6_metric;
        u8                              fib6_protocol;
        u8                              fib6_type;

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a366c05..abcb5ae 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -520,10 +520,11 @@ static void rt6_probe_deferred(struct work_struct *w)
 
 static void rt6_probe(struct fib6_info *rt)
 {
-       struct __rt6_probe_work *work;
+       struct __rt6_probe_work *work = NULL;
        const struct in6_addr *nh_gw;
        struct neighbour *neigh;
        struct net_device *dev;
+       struct inet6_dev *idev;
 
        /*
         * Okay, this does not seem to be appropriate
@@ -539,15 +540,12 @@ static void rt6_probe(struct fib6_info *rt)
        nh_gw = &rt->fib6_nh.nh_gw;
        dev = rt->fib6_nh.nh_dev;
        rcu_read_lock_bh();
+       idev = __in6_dev_get(dev);
        neigh = __ipv6_neigh_lookup_noref(dev, nh_gw);
        if (neigh) {
-               struct inet6_dev *idev;
-
                if (neigh->nud_state & NUD_VALID)
                        goto out;
 
-               idev = __in6_dev_get(dev);
-               work = NULL;
                write_lock(&neigh->lock);
                if (!(neigh->nud_state & NUD_VALID) &&
                    time_after(jiffies,
@@ -557,11 +555,13 @@ static void rt6_probe(struct fib6_info *rt)
                                __neigh_set_probe_once(neigh);
                }
                write_unlock(&neigh->lock);
-       } else {
+       } else if (time_after(jiffies, rt->last_probe +
+                                      idev->cnf.rtr_probe_interval)) {
                work = kmalloc(sizeof(*work), GFP_ATOMIC);
        }
 
        if (work) {
+               rt->last_probe = jiffies;
                INIT_WORK(&work->work, rt6_probe_deferred);
                work->target = *nh_gw;
                dev_hold(dev);