ipv4: use next hop exceptions also for input routes
Commit d2d68ba9 (ipv4: Cache input routes in fib_info nexthops)
assmued that "locally destined, and routed packets, never trigger
PMTU events or redirects that will be processed by us".
However, it seems that tunnel devices do trigger PMTU events in certain
cases. At least ip_gre, ip6_gre, sit, and ipip do use the inner flow's
skb_dst(skb)->ops->update_pmtu to propage mtu information from the
outer flows. These can cause the inner flow mtu to be decreased. If
next hop exceptions are not consulted for pmtu, IP fragmentation will
not be done properly for these routes.
It also seems that we really need to have the PMTU information always
for netfilter TCPMSS clamp-to-pmtu feature to work properly.
So for the time being, cache separate copies of input routes for
each next hop exception.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 44424e9..aac8553 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -56,7 +56,8 @@
u32 fnhe_pmtu;
__be32 fnhe_gw;
unsigned long fnhe_expires;
- struct rtable __rcu *fnhe_rth;
+ struct rtable __rcu *fnhe_rth_input;
+ struct rtable __rcu *fnhe_rth_output;
unsigned long fnhe_stamp;
};
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 8f6cb7a..d5dbca5 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -169,7 +169,8 @@
next = rcu_dereference_protected(fnhe->fnhe_next, 1);
- rt_fibinfo_free(&fnhe->fnhe_rth);
+ rt_fibinfo_free(&fnhe->fnhe_rth_input);
+ rt_fibinfo_free(&fnhe->fnhe_rth_output);
kfree(fnhe);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f3fa42e..a9a54a2 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -565,10 +565,25 @@
static DEFINE_SPINLOCK(fnhe_lock);
+static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
+{
+ struct rtable *rt;
+
+ rt = rcu_dereference(fnhe->fnhe_rth_input);
+ if (rt) {
+ RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
+ rt_free(rt);
+ }
+ rt = rcu_dereference(fnhe->fnhe_rth_output);
+ if (rt) {
+ RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
+ rt_free(rt);
+ }
+}
+
static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
{
struct fib_nh_exception *fnhe, *oldest;
- struct rtable *orig;
oldest = rcu_dereference(hash->chain);
for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
@@ -576,11 +591,7 @@
if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
oldest = fnhe;
}
- orig = rcu_dereference(oldest->fnhe_rth);
- if (orig) {
- RCU_INIT_POINTER(oldest->fnhe_rth, NULL);
- rt_free(orig);
- }
+ fnhe_flush_routes(oldest);
return oldest;
}
@@ -644,7 +655,10 @@
fnhe->fnhe_expires = max(1UL, expires);
}
/* Update all cached dsts too */
- rt = rcu_dereference(fnhe->fnhe_rth);
+ rt = rcu_dereference(fnhe->fnhe_rth_input);
+ if (rt)
+ fill_route_from_fnhe(rt, fnhe);
+ rt = rcu_dereference(fnhe->fnhe_rth_output);
if (rt)
fill_route_from_fnhe(rt, fnhe);
} else {
@@ -668,6 +682,10 @@
* stale, so anyone caching it rechecks if this exception
* applies to them.
*/
+ rt = rcu_dereference(nh->nh_rth_input);
+ if (rt)
+ rt->dst.obsolete = DST_OBSOLETE_KILL;
+
for_each_possible_cpu(i) {
struct rtable __rcu **prt;
prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
@@ -1242,25 +1260,36 @@
spin_lock_bh(&fnhe_lock);
if (daddr == fnhe->fnhe_daddr) {
+ struct rtable __rcu **porig;
+ struct rtable *orig;
int genid = fnhe_genid(dev_net(rt->dst.dev));
- struct rtable *orig = rcu_dereference(fnhe->fnhe_rth);
+
+ if (rt_is_input_route(rt))
+ porig = &fnhe->fnhe_rth_input;
+ else
+ porig = &fnhe->fnhe_rth_output;
+ orig = rcu_dereference(*porig);
if (fnhe->fnhe_genid != genid) {
fnhe->fnhe_genid = genid;
fnhe->fnhe_gw = 0;
fnhe->fnhe_pmtu = 0;
fnhe->fnhe_expires = 0;
+ fnhe_flush_routes(fnhe);
+ orig = NULL;
}
fill_route_from_fnhe(rt, fnhe);
if (!rt->rt_gateway)
rt->rt_gateway = daddr;
- rcu_assign_pointer(fnhe->fnhe_rth, rt);
- if (orig)
- rt_free(orig);
+ if (!(rt->dst.flags & DST_NOCACHE)) {
+ rcu_assign_pointer(*porig, rt);
+ if (orig)
+ rt_free(orig);
+ ret = true;
+ }
fnhe->fnhe_stamp = jiffies;
- ret = true;
}
spin_unlock_bh(&fnhe_lock);
@@ -1492,6 +1521,7 @@
struct in_device *in_dev,
__be32 daddr, __be32 saddr, u32 tos)
{
+ struct fib_nh_exception *fnhe;
struct rtable *rth;
int err;
struct in_device *out_dev;
@@ -1538,8 +1568,13 @@
}
}
+ fnhe = find_exception(&FIB_RES_NH(*res), daddr);
if (do_cache) {
- rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
+ if (fnhe != NULL)
+ rth = rcu_dereference(fnhe->fnhe_rth_input);
+ else
+ rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
+
if (rt_cache_valid(rth)) {
skb_dst_set_noref(skb, &rth->dst);
goto out;
@@ -1567,7 +1602,7 @@
rth->dst.input = ip_forward;
rth->dst.output = ip_output;
- rt_set_nexthop(rth, daddr, res, NULL, res->fi, res->type, itag);
+ rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
skb_dst_set(skb, &rth->dst);
out:
err = 0;
@@ -1882,7 +1917,7 @@
fnhe = find_exception(nh, fl4->daddr);
if (fnhe)
- prth = &fnhe->fnhe_rth;
+ prth = &fnhe->fnhe_rth_output;
else {
if (unlikely(fl4->flowi4_flags &
FLOWI_FLAG_KNOWN_NH &&