From patchwork Tue Apr 21 12:17:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cambda Zhu X-Patchwork-Id: 220853 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham 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 90092C54FD0 for ; Tue, 21 Apr 2020 12:18:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72C40206A5 for ; Tue, 21 Apr 2020 12:18:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728645AbgDUMSx (ORCPT ); Tue, 21 Apr 2020 08:18:53 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:48544 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726018AbgDUMSw (ORCPT ); Tue, 21 Apr 2020 08:18:52 -0400 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R121e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e01355; MF=cambda@linux.alibaba.com; NM=1; PH=DS; RN=4; SR=0; TI=SMTPD_---0TwElGzd_1587471526; Received: from localhost(mailfrom:cambda@linux.alibaba.com fp:SMTPD_---0TwElGzd_1587471526) by smtp.aliyun-inc.com(127.0.0.1); Tue, 21 Apr 2020 20:18:46 +0800 From: Cambda Zhu To: netdev Cc: Dust Li , Tony Lu , Cambda Zhu Subject: [PATCH net-next] net: Add TCP_FORCE_LINGER2 to TCP setsockopt Date: Tue, 21 Apr 2020 20:17:37 +0800 Message-Id: <20200421121737.3269-1-cambda@linux.alibaba.com> X-Mailer: git-send-email 2.16.6 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch adds a new TCP socket option named TCP_FORCE_LINGER2. The option has same behavior as TCP_LINGER2, except the tp->linger2 value can be greater than sysctl_tcp_fin_timeout if the user_ns is capable with CAP_NET_ADMIN. As a server, different sockets may need different FIN-WAIT timeout and in most cases the system default value will be used. The timeout can be adjusted by setting TCP_LINGER2 but cannot be greater than the system default value. If one socket needs a timeout greater than the default, we have to adjust the sysctl which affects all sockets using the system default value. And if we want to adjust it for just one socket and keep the original value for others, all the other sockets have to set TCP_LINGER2. But with TCP_FORCE_LINGER2, the net admin can set greater tp->linger2 than the default for one socket and keep the sysctl_tcp_fin_timeout unchanged. Signed-off-by: Cambda Zhu --- include/uapi/linux/capability.h | 1 + include/uapi/linux/tcp.h | 1 + net/ipv4/tcp.c | 9 +++++++++ 3 files changed, 11 insertions(+) diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h index 272dc69fa080..0e30c9756a04 100644 --- a/include/uapi/linux/capability.h +++ b/include/uapi/linux/capability.h @@ -199,6 +199,7 @@ struct vfs_ns_cap_data { /* Allow multicasting */ /* Allow read/write of device-specific registers */ /* Allow activation of ATM control sockets */ +/* Allow setting TCP_LINGER2 regardless of sysctl_tcp_fin_timeout */ #define CAP_NET_ADMIN 12 diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index f2acb2566333..e21e0ce98ca1 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -128,6 +128,7 @@ enum { #define TCP_CM_INQ TCP_INQ #define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */ +#define TCP_FORCE_LINGER2 38 /* Set TCP_LINGER2 regardless of sysctl_tcp_fin_timeout */ #define TCP_REPAIR_ON 1 diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 6d87de434377..898a675d863e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3149,6 +3149,15 @@ static int do_tcp_setsockopt(struct sock *sk, int level, tcp_enable_tx_delay(); tp->tcp_tx_delay = val; break; + case TCP_FORCE_LINGER2: + if (val < 0) + tp->linger2 = -1; + else if (val > net->ipv4.sysctl_tcp_fin_timeout / HZ && + !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) + tp->linger2 = 0; + else + tp->linger2 = val * HZ; + break; default: err = -ENOPROTOOPT; break;