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Message-ID: <CANn89iJ4W3DSGVm89CQ8yz=VYyLeCY4_4cOJuGULoxft8ezO-w@mail.gmail.com>
Date: Thu, 30 Nov 2023 17:17:57 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Guillaume Nault <gnault@...hat.com>
Cc: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
David Ahern <dsahern@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>,
Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [PATCH net-next v3] tcp: Dump bound-only sockets in inet_diag.
On Thu, Nov 30, 2023 at 4:40 PM Guillaume Nault <gnault@...hat.com> wrote:
>
> Walk the hashinfo->bhash2 table so that inet_diag can dump TCP sockets
> that are bound but haven't yet called connect() or listen().
>
> The code is inspired by the ->lhash2 loop. However there's no manual
> test of the source port, since this kind of filtering is already
> handled by inet_diag_bc_sk(). Also, a maximum of 16 sockets are dumped
> at a time, to avoid running with bh disabled for too long.
>
> There's no TCP state for bound but otherwise inactive sockets. Such
> sockets normally map to TCP_CLOSE. However, "ss -l", which is supposed
> to only dump listening sockets, actually requests the kernel to dump
> sockets in either the TCP_LISTEN or TCP_CLOSE states. To avoid dumping
> bound-only sockets with "ss -l", we therefore need to define a new
> pseudo-state (TCP_BOUND_INACTIVE) that user space will be able to set
> explicitly.
>
> With an IPv4, an IPv6 and an IPv6-only socket, bound respectively to
> 40000, 64000, 60000, an updated version of iproute2 could work as
> follow:
>
> $ ss -t state bound-inactive
> Recv-Q Send-Q Local Address:Port Peer Address:Port Process
> 0 0 0.0.0.0:40000 0.0.0.0:*
> 0 0 [::]:60000 [::]:*
> 0 0 *:64000 *:*
>
> Signed-off-by: Guillaume Nault <gnault@...hat.com>
> ---
>
> v3:
> * Grab sockets with sock_hold(), instead of refcount_inc_not_zero()
> (Kuniyuki Iwashima).
> * Use a new TCP pseudo-state (TCP_BOUND_INACTIVE), to dump bound-only
> sockets, so that "ss -l" won't print them (Eric Dumazet).
>
> +pause_bind_walk:
> + spin_unlock_bh(&ibb->lock);
> +
> + res = 0;
> + for (idx = 0; idx < accum; idx++) {
> + if (res >= 0) {
> + res = inet_sk_diag_fill(sk_arr[idx],
> + NULL, skb, cb,
> + r, NLM_F_MULTI,
> + net_admin);
> + if (res < 0)
> + num = num_arr[idx];
> + }
> + sock_gen_put(sk_arr[idx]);
nit: this could be a mere sock_put(), because only full sockets are
hashed in bhash2[]
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
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