From patchwork Wed Sep 29 08:45:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Jian X-Patchwork-Id: 12524927 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B12FC4332F for ; Wed, 29 Sep 2021 08:45:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6132561357 for ; Wed, 29 Sep 2021 08:45:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244799AbhI2IrE (ORCPT ); Wed, 29 Sep 2021 04:47:04 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:26967 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244764AbhI2IrE (ORCPT ); Wed, 29 Sep 2021 04:47:04 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HK8wZ6RpNzbmrv; Wed, 29 Sep 2021 16:41:02 +0800 (CST) Received: from dggema772-chm.china.huawei.com (10.1.198.214) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 29 Sep 2021 16:45:20 +0800 Received: from huawei.com (10.175.101.6) by dggema772-chm.china.huawei.com (10.1.198.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 29 Sep 2021 16:45:17 +0800 From: Liu Jian To: , , , , , , , , , , , , , , , , CC: Subject: [PATCH] tcp_bpf: Fix one concurrency problem in the tcp_bpf_send_verdict function Date: Wed, 29 Sep 2021 16:45:29 +0800 Message-ID: <20210929084529.96583-1-liujian56@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggema772-chm.china.huawei.com (10.1.198.214) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org In the following cases: We need to redirect the first msg to sock1 and the second msg to sock2. The sock lock needs to be released at __SK_REDIRECT and to get another sock lock, this will cause the probability that psock->eval is not set to __SK_NONE when the second msg comes. If psock does not set apple bytes, fix this by do the cleanup before releasing the sock lock. And keep the original logic in other cases. Signed-off-by: Liu Jian --- net/ipv4/tcp_bpf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index d3e9386b493e..02442e43ac4d 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -232,6 +232,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, bool cork = false, enospc = sk_msg_full(msg); struct sock *sk_redir; u32 tosend, delta = 0; + u32 eval = __SK_NONE; int ret; more_data: @@ -274,6 +275,12 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, break; case __SK_REDIRECT: sk_redir = psock->sk_redir; + if (!psock->apply_bytes) { + /* Clean up before releasing the sock lock. */ + eval = psock->eval; + psock->eval = __SK_NONE; + psock->sk_redir = NULL; + } sk_msg_apply_bytes(psock, tosend); if (psock->cork) { cork = true; @@ -281,7 +288,12 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, } sk_msg_return(sk, msg, tosend); release_sock(sk); + ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags); + + if (eval == __SK_REDIRECT) + sock_put(sk_redir); + lock_sock(sk); if (unlikely(ret < 0)) { int free = sk_msg_free_nocharge(sk, msg);