Commit 45e4fd26 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
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ipv6: Only create RTF_CACHE routes after encountering pmtu exception



This patch creates a RTF_CACHE routes only after encountering a pmtu
exception.

After ip6_rt_update_pmtu() has inserted the RTF_CACHE route to the fib6
tree, the rt->rt6i_node->fn_sernum is bumped which will fail the
ip6_dst_check() and trigger a relookup.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8b9df265
......@@ -202,7 +202,7 @@ static inline struct in6_addr *rt6_nexthop(struct rt6_info *rt,
{
if (rt->rt6i_flags & RTF_GATEWAY)
return &rt->rt6i_gateway;
else if (rt->rt6i_flags & RTF_CACHE)
else if (unlikely(rt->rt6i_flags & RTF_CACHE))
return &rt->rt6i_dst.addr;
else
return daddr;
......
......@@ -738,6 +738,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
rt6_clean_expires(iter);
else
rt6_set_expires(iter, rt->dst.expires);
iter->rt6i_pmtu = rt->rt6i_pmtu;
return -EEXIST;
}
/* If we have the same destination and the same metric,
......
......@@ -873,16 +873,13 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
struct flowi6 *fl6, int flags)
{
struct fib6_node *fn, *saved_fn;
struct rt6_info *rt, *nrt;
struct rt6_info *rt;
int strict = 0;
int attempts = 3;
int err;
strict |= flags & RT6_LOOKUP_F_IFACE;
if (net->ipv6.devconf_all->forwarding == 0)
strict |= RT6_LOOKUP_F_REACHABLE;
redo_fib6_lookup_lock:
read_lock_bh(&table->tb6_lock);
fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
......@@ -901,46 +898,12 @@ redo_rt6_select:
strict &= ~RT6_LOOKUP_F_REACHABLE;
fn = saved_fn;
goto redo_rt6_select;
} else {
dst_hold(&rt->dst);
read_unlock_bh(&table->tb6_lock);
goto out2;
}
}
dst_hold(&rt->dst);
read_unlock_bh(&table->tb6_lock);
if (rt->rt6i_flags & RTF_CACHE)
goto out2;
if (!rt6_is_gw_or_nonexthop(rt) ||
!(rt->dst.flags & DST_HOST) || !(rt->rt6i_flags & RTF_LOCAL))
nrt = ip6_rt_cache_alloc(rt, &fl6->daddr, &fl6->saddr);
else
goto out2;
ip6_rt_put(rt);
rt = nrt ? : net->ipv6.ip6_null_entry;
dst_hold(&rt->dst);
if (nrt) {
err = ip6_ins_rt(nrt);
if (!err)
goto out2;
}
if (--attempts <= 0)
goto out2;
/*
* Race condition! In the gap, when table->tb6_lock was
* released someone could insert this route. Relookup.
*/
ip6_rt_put(rt);
goto redo_fib6_lookup_lock;
out2:
rt6_dst_from_metrics_check(rt);
rt->dst.lastuse = jiffies;
rt->dst.__use++;
......@@ -1113,24 +1076,63 @@ static void ip6_link_failure(struct sk_buff *skb)
}
}
static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb, u32 mtu)
static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
{
struct net *net = dev_net(rt->dst.dev);
rt->rt6i_flags |= RTF_MODIFIED;
rt->rt6i_pmtu = mtu;
rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires);
}
static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
const struct ipv6hdr *iph, u32 mtu)
{
struct rt6_info *rt6 = (struct rt6_info *)dst;
dst_confirm(dst);
if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
struct net *net = dev_net(dst->dev);
if (rt6->rt6i_flags & RTF_LOCAL)
return;
rt6->rt6i_flags |= RTF_MODIFIED;
if (mtu < IPV6_MIN_MTU)
mtu = IPV6_MIN_MTU;
dst_confirm(dst);
mtu = max_t(u32, mtu, IPV6_MIN_MTU);
if (mtu >= dst_mtu(dst))
return;
rt6->rt6i_pmtu = mtu;
rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires);
if (rt6->rt6i_flags & RTF_CACHE) {
rt6_do_update_pmtu(rt6, mtu);
} else {
const struct in6_addr *daddr, *saddr;
struct rt6_info *nrt6;
if (iph) {
daddr = &iph->daddr;
saddr = &iph->saddr;
} else if (sk) {
daddr = &sk->sk_v6_daddr;
saddr = &inet6_sk(sk)->saddr;
} else {
return;
}
nrt6 = ip6_rt_cache_alloc(rt6, daddr, saddr);
if (nrt6) {
rt6_do_update_pmtu(nrt6, mtu);
/* ip6_ins_rt(nrt6) will bump the
* rt6->rt6i_node->fn_sernum
* which will fail the next rt6_check() and
* invalidate the sk->sk_dst_cache.
*/
ip6_ins_rt(nrt6);
}
}
}
static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb, u32 mtu)
{
__ip6_rt_update_pmtu(dst, sk, skb ? ipv6_hdr(skb) : NULL, mtu);
}
void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
int oif, u32 mark)
{
......@@ -1147,7 +1149,7 @@ void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
dst = ip6_route_output(net, NULL, &fl6);
if (!dst->error)
ip6_rt_update_pmtu(dst, NULL, skb, ntohl(mtu));
__ip6_rt_update_pmtu(dst, NULL, iph, ntohl(mtu));
dst_release(dst);
}
EXPORT_SYMBOL_GPL(ip6_update_pmtu);
......
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