On Sat, Mar 5, 2016 at 9:55 PM, David Miller <da...@davemloft.net> wrote:
> From: Wei Wang <wei...@google.com>
> Date: Wed, 2 Mar 2016 11:19:21 -0800
>
>> @@ -566,7 +567,16 @@ void __udp6_lib_err(struct sk_buff *skb, struct
>> inet6_skb_parm *opt,
>> if (type == ICMPV6_PKT_TOOBIG) {
>> if (!ip6_sk_accept_pmtu(sk))
>> goto out;
>> - ip6_sk_update_pmtu(skb, sk, info);
>> + bh_lock_sock(sk);
>> + if (sk->sk_state == TCP_ESTABLISHED &&
>> + !sock_owned_by_user(sk) &&
>> + ipv6_addr_equal(saddr, &sk->sk_v6_rcv_saddr) &&
>> + ipv6_addr_equal(daddr, &sk->sk_v6_daddr) &&
>> + uh->dest == sk->sk_dport)
>> + inet6_csk_update_pmtu(sk, ntohl(info));
>
> If I apply this patch it will hide a bug.
>
> Why isn't ip6_sk_update_pmtu() matching the same route as the
> one attached to the socket?
>
> I'd prefer you figure out what part of the lookup key used is
> wrong, and fix that instead.
>
The dst itself is the same than the socket sk_dst_cache, but
__ip6_rt_update_pmtu() sees rt6_cache_allowed_for_pmtu()
We endup doing :
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);
}
But apparently the sk->sk_dst_cache is _not_ invalidated, even if the
comment loudly claims so.
