From: Martin KaFai Lau <kafai@fb.com>
To: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Cc: <andrii@kernel.org>, <ast@kernel.org>, <benh@amazon.com>,
<bpf@vger.kernel.org>, <daniel@iogearbox.net>,
<davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
<kuni1840@gmail.com>, <linux-kernel@vger.kernel.org>,
<netdev@vger.kernel.org>
Subject: Re: [PATCH v6 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the reuseport group.
Date: Thu, 20 May 2021 14:22:01 -0700 [thread overview]
Message-ID: <20210520212201.zq3ozwx3vrobd2ua@kafai-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20210520085117.48629-1-kuniyu@amazon.co.jp>
On Thu, May 20, 2021 at 05:51:17PM +0900, Kuniyuki Iwashima wrote:
> From: Martin KaFai Lau <kafai@fb.com>
> Date: Wed, 19 May 2021 23:26:48 -0700
> > On Mon, May 17, 2021 at 09:22:50AM +0900, Kuniyuki Iwashima wrote:
> >
> > > +static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse,
> > > + struct sock_reuseport *reuse, bool bind_inany)
> > > +{
> > > + if (old_reuse == reuse) {
> > > + /* If sk was in the same reuseport group, just pop sk out of
> > > + * the closed section and push sk into the listening section.
> > > + */
> > > + __reuseport_detach_closed_sock(sk, old_reuse);
> > > + __reuseport_add_sock(sk, old_reuse);
> > > + return 0;
> > > + }
> > > +
> > > + if (!reuse) {
> > > + /* In bind()/listen() path, we cannot carry over the eBPF prog
> > > + * for the shutdown()ed socket. In setsockopt() path, we should
> > > + * not change the eBPF prog of listening sockets by attaching a
> > > + * prog to the shutdown()ed socket. Thus, we will allocate a new
> > > + * reuseport group and detach sk from the old group.
> > > + */
> > For the reuseport_attach_prog() path, I think it needs to consider
> > the reuse->num_closed_socks != 0 case also and that should belong
> > to the resurrect case. For example, when
> > sk_unhashed(sk) but sk->sk_reuseport == 0.
>
> In the path, reuseport_resurrect() is called from reuseport_alloc() only
> if reuse->num_closed_socks != 0.
>
>
> > @@ -92,6 +117,14 @@ int reuseport_alloc(struct sock *sk, bool bind_inany)
> > reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
> > lockdep_is_held(&reuseport_lock));
> > if (reuse) {
> > + if (reuse->num_closed_socks) {
>
> But, should this be
>
> if (sk->sk_state == TCP_CLOSE && reuse->num_closed_socks)
>
> because we need not allocate a new group when we attach a bpf prog to
> listeners?
The reuseport_alloc() is fine as is. No need to change.
I should have copied reuseport_attach_prog() in the last reply and
commented there instead.
I meant reuseport_attach_prog() needs a change. In reuseport_attach_prog(),
iiuc, currently passing the "else if (!rcu_access_pointer(sk->sk_reuseport_cb))"
check implies the sk was (and still is) hashed with sk_reuseport enabled
because the current behavior would have set sk_reuseport_cb to NULL during
unhash but it is no longer true now. For example, this will break:
1. shutdown(lsk); /* lsk was bound with sk_reuseport enabled */
2. setsockopt(lsk, ..., SO_REUSEPORT, &zero, ...); /* disable sk_reuseport */
3. setsockopt(lsk, ..., SO_ATTACH_REUSEPORT_EBPF, &prog_fd, ...);
^---- /* This will work now because sk_reuseport_cb is not NULL.
* However, it shouldn't be allowed.
*/
I am thinking something like this (uncompiled code):
int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog)
{
struct sock_reuseport *reuse;
struct bpf_prog *old_prog;
if (sk_unhashed(sk)) {
int err;
if (!sk->sk_reuseport)
return -EINVAL;
err = reuseport_alloc(sk, false);
if (err)
return err;
} else if (!rcu_access_pointer(sk->sk_reuseport_cb)) {
/* The socket wasn't bound with SO_REUSEPORT */
return -EINVAL;
}
/* ... */
}
WDYT?
next prev parent reply other threads:[~2021-05-20 21:22 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 0:22 [PATCH v6 bpf-next 00/11] Socket migration for SO_REUSEPORT Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 01/11] net: Introduce net.ipv4.tcp_migrate_req Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 02/11] tcp: Add num_closed_socks to struct sock_reuseport Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the reuseport group Kuniyuki Iwashima
2021-05-20 6:26 ` Martin KaFai Lau
2021-05-20 8:51 ` Kuniyuki Iwashima
2021-05-20 21:22 ` Martin KaFai Lau [this message]
2021-05-20 22:54 ` Kuniyuki Iwashima
2021-05-20 23:39 ` Martin KaFai Lau
2021-05-21 0:26 ` Kuniyuki Iwashima
2021-05-21 4:47 ` Martin KaFai Lau
2021-05-21 5:15 ` Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 04/11] tcp: Add reuseport_migrate_sock() to select a new listener Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 05/11] tcp: Migrate TCP_ESTABLISHED/TCP_SYN_RECV sockets in accept queues Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 06/11] tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 07/11] tcp: Migrate TCP_NEW_SYN_RECV requests at receiving the final ACK Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 08/11] bpf: Support BPF_FUNC_get_socket_cookie() for BPF_PROG_TYPE_SK_REUSEPORT Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 09/11] bpf: Support socket migration by eBPF Kuniyuki Iwashima
2021-05-20 6:27 ` Martin KaFai Lau
2021-05-20 8:54 ` Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 10/11] libbpf: Set expected_attach_type for BPF_PROG_TYPE_SK_REUSEPORT Kuniyuki Iwashima
2021-05-17 0:22 ` [PATCH v6 bpf-next 11/11] bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE Kuniyuki Iwashima
2021-05-20 6:30 ` [PATCH v6 bpf-next 00/11] Socket migration for SO_REUSEPORT Martin KaFai Lau
2021-05-20 8:58 ` Kuniyuki Iwashima
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