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