From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6F1AC43461 for ; Thu, 20 May 2021 22:54:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFC6261074 for ; Thu, 20 May 2021 22:54:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232545AbhETW4U (ORCPT ); Thu, 20 May 2021 18:56:20 -0400 Received: from smtp-fw-80006.amazon.com ([99.78.197.217]:51941 "EHLO smtp-fw-80006.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231967AbhETW4T (ORCPT ); Thu, 20 May 2021 18:56:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.co.jp; i=@amazon.co.jp; q=dns/txt; s=amazon201209; t=1621551298; x=1653087298; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=x+CmPkt+gS5GHDvNirO+GVQ5AFM4U/vtAYwbl2/w4vw=; b=ngENQGCm+/3DPzB+MofJdkiWd+Q30OlEdbYaOofXogc2yaa8EOflaJnj 2bBmSTgjyXtAJWPY6tBC8kwzMrjWxLDOKWVCbTs6XkskTs0ZvGTXA7gAp 0bTveUVxVQFxT8AIdmcaHAUo0+a2iAmjddOFsxsfZ00YUJdthUgYmssuW s=; X-IronPort-AV: E=Sophos;i="5.82,313,1613433600"; d="scan'208";a="2453487" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-2c-87a10be6.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-80006.pdx80.corp.amazon.com with ESMTP; 20 May 2021 22:54:58 +0000 Received: from EX13MTAUWB001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-2c-87a10be6.us-west-2.amazon.com (Postfix) with ESMTPS id D8908A1EEA; Thu, 20 May 2021 22:54:56 +0000 (UTC) Received: from EX13D04ANC001.ant.amazon.com (10.43.157.89) by EX13MTAUWB001.ant.amazon.com (10.43.161.249) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Thu, 20 May 2021 22:54:55 +0000 Received: from 88665a182662.ant.amazon.com (10.43.160.137) by EX13D04ANC001.ant.amazon.com (10.43.157.89) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Thu, 20 May 2021 22:54:51 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , , , , , Subject: Re: [PATCH v6 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the reuseport group. Date: Fri, 21 May 2021 07:54:48 +0900 Message-ID: <20210520225448.14157-1-kuniyu@amazon.co.jp> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210520212201.zq3ozwx3vrobd2ua@kafai-mbp.dhcp.thefacebook.com> References: <20210520212201.zq3ozwx3vrobd2ua@kafai-mbp.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.43.160.137] X-ClientProxiedBy: EX13D21UWB002.ant.amazon.com (10.43.161.177) To EX13D04ANC001.ant.amazon.com (10.43.157.89) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Martin KaFai Lau Date: Thu, 20 May 2021 14:22:01 -0700 > On Thu, May 20, 2021 at 05:51:17PM +0900, Kuniyuki Iwashima wrote: > > From: Martin KaFai Lau > > 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 missed sk_unhashed(sk) prevents calling reuseport_alloc() if sk_state == TCP_LISTEN. I'll keep it as is. > > 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. > */ Thank you for explanation, I understood the case. Exactly, I've confirmed that the case succeeded in the setsockopt() and I could change the active listeners' prog via a shutdowned socket. > > 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? I tested this change worked fine. I think this change should be added in reuseport_detach_prog() also. ---8<--- int reuseport_detach_prog(struct sock *sk) { struct sock_reuseport *reuse; struct bpf_prog *old_prog; if (!rcu_access_pointer(sk->sk_reuseport_cb)) return sk->sk_reuseport ? -ENOENT : -EINVAL; ---8<--- Another option is to add the check in sock_setsockopt(): SO_ATTACH_REUSEPORT_[CE]BPF, SO_DETACH_REUSEPORT_BPF. Which do you think is better ?