inet_diag: fix inet_diag_dump_icsk() to use correct state for timewait sockets

Fix inet_diag_dump_icsk() to reflect the fact that both TCP_TIME_WAIT
and TCP_FIN_WAIT2 connections are represented by inet_timewait_sock
(not just TIME_WAIT), and for such sockets the tw_substate field holds
the real state, which can be either TCP_TIME_WAIT or TCP_FIN_WAIT2.

This brings the inet_diag state-matching code in line with the field
it uses to populate idiag_state. This is also analogous to the info
exported in /proc/net/tcp, where get_tcp4_sock() exports sk->sk_state
and get_timewait4_sock() exports tw->tw_substate.

Before fixing this, (a) neither "ss -nemoi" nor "ss -nemoi state
fin-wait-2" would return a socket in TCP_FIN_WAIT2; and (b) "ss -nemoi
state time-wait" would also return sockets in state TCP_FIN_WAIT2.

This is an old bug that predates 05dbc7b ("tcp/dccp: remove twchain").

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index a0f52dac8940..e34dccbc4d70 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -930,12 +930,15 @@ skip_listen_ht:
                 spin_lock_bh(lock);
                 sk_nulls_for_each(sk, node, &head->chain) {
                         int res;
+                        int state;
 
                         if (!net_eq(sock_net(sk), net))
                                 continue;
                         if (num < s_num)
                                 goto next_normal;
-                        if (!(r->idiag_states & (1 << sk->sk_state)))
+                        state = (sk->sk_state == TCP_TIME_WAIT) ?
+                                inet_twsk(sk)->tw_substate : sk->sk_state;
+                        if (!(r->idiag_states & (1 << state)))
                                 goto next_normal;
                         if (r->sdiag_family != AF_UNSPEC &&
                             sk->sk_family != r->sdiag_family)