From patchwork Fri Aug 28 20:39:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Groeneveld X-Patchwork-Id: 261786 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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS 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 D4994C433E2 for ; Fri, 28 Aug 2020 20:48:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAD26207DA for ; Fri, 28 Aug 2020 20:48:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=bartavi.nl header.i=@bartavi.nl header.b="Hj/whvg/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726536AbgH1Usq (ORCPT ); Fri, 28 Aug 2020 16:48:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726033AbgH1Usp (ORCPT ); Fri, 28 Aug 2020 16:48:45 -0400 Received: from outbound.soverin.net (outbound.soverin.net [IPv6:2a01:4f8:fff0:2d:8::218]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 862B7C061264; Fri, 28 Aug 2020 13:48:45 -0700 (PDT) Received: from smtp.soverin.net (unknown [10.10.3.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by outbound.soverin.net (Postfix) with ESMTPS id 1A7FF60901; Fri, 28 Aug 2020 20:40:24 +0000 (UTC) Received: from smtp.soverin.net (smtp.soverin.net [159.69.232.142]) by soverin.net DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=bartavi.nl; s=soverin; t=1598647221; bh=8xkQ/ltprH+eyjeuEUkHOc9x8L26C1hcmS7SUa7P7s4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hj/whvg/NYNju60G7k6okxcEe68OESHMzXUKNQn9IYYLndd/Yd9gny+H1fwcQSvkD 2JwCG+2FJxvicZRd9f0xcZRlXzpahU810yHXH5to4cAlrC9Fzb8upX3+CMgdEpGv3F TbAUtGavlxZLbvjYM1G9zQhlgAGI8SpQWZCpCBUmRKut1A1YZ9HNzkUb77nAQJj6dH 25QuadkCxqOAgFeJk5yusZjBB2iBUUMbThFzDeG4LPBbbgQRt1S5YqNuJIW4knuiOQ lgJXZzdKCdS8TG4qz8+SpN3j1Ri3yyR9nBO/+qyd9Ek5lYG3XRY4J46YCboRK6u6XI hZ2PU23d7Fccg== From: Bart Groeneveld To: Patches internal Cc: "David S . Miller" , Jakub Kicinski , Jonathan Corbet , Alexey Kuznetsov , Hideaki YOSHIFUJI , netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Bart Groeneveld Subject: [PATCH v2] net: Use standardized (IANA) local port range Date: Fri, 28 Aug 2020 22:39:59 +0200 Message-Id: <20200828203959.32010-1-avi@bartavi.nl> In-Reply-To: <20200821142533.45694-1-avi@bartavi.nl> References: <20200821142533.45694-1-avi@bartavi.nl> MIME-Version: 1.0 X-Spam: Yes Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org IANA specifies User ports as 1024-49151, and Private ports (local/ephemeral/dynamic/w/e) as 49152-65535 [1]. This means Linux uses 32768-49151 'illegally'. This is not just a matter of following specifications: IANA actually assigns numbers in this range [1]. I understand that Linux uses 61000-65535 for masquarading/NAT [2], so I left the high value at 60999. This means the high value still does not follow the specification, but it also doesn't conflict with it. This change will effectively halve the available ephemeral ports, increasing the risk of port exhaustion. But: a) I don't think that warrants ignoring standards. Consider for example setting up a (corporate) firewall blocking all unknown external services. It will only allow outgoing trafiic at port 80,443 and 49152-65535. A Linux computer behind such a firewall will not be able to connect to *any* external service *half of the time*. Of course, the firewall can be adjusted to also allow 32768-49151, but that allows computers to use some services against the policy. b) It is only an issue with more than 11848 *outgoing* connections. I think that is a niche case (I know, citation needed, but still). If someone finds themselves in such a niche case, they can still modify ip_local_port_range. This patch keeps the low and high value at different parity, as to optimize port assignment [3]. [1]: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.txt [2]: https://marc.info/?l=linux-kernel&m=117900026927289 [3]: See for example commit 1580ab63fc9a03593072cc5656167a75c4f1d173 ("tcp/dccp: better use of ephemeral ports in connect()") Signed-off-by: Bart Groeneveld --- Documentation/networking/ip-sysctl.rst | 4 ++-- net/ipv4/af_inet.c | 2 +- net/ipv4/inet_connection_sock.c | 2 +- net/ipv4/inet_hashtables.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 837d51f9e1fa..5048b326f773 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1024,7 +1024,7 @@ ip_local_port_range - 2 INTEGERS If possible, it is better these numbers have different parity (one even and one odd value). Must be greater than or equal to ip_unprivileged_port_start. - The default values are 32768 and 60999 respectively. + The default values are 49152 and 60999 respectively. ip_local_reserved_ports - list of comma separated ranges Specify the ports which are reserved for known third-party @@ -1047,7 +1047,7 @@ ip_local_reserved_ports - list of comma separated ranges ip_local_port_range, e.g.:: $ cat /proc/sys/net/ipv4/ip_local_port_range - 32000 60999 + 49152 60999 $ cat /proc/sys/net/ipv4/ip_local_reserved_ports 8080,9148 diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 4307503a6f0b..f95a9ffffdc9 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1838,7 +1838,7 @@ static __net_init int inet_init_net(struct net *net) * Set defaults for local port range */ seqlock_init(&net->ipv4.ip_local_ports.lock); - net->ipv4.ip_local_ports.range[0] = 32768; + net->ipv4.ip_local_ports.range[0] = 49152; net->ipv4.ip_local_ports.range[1] = 60999; seqlock_init(&net->ipv4.ping_group_range.lock); diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index b457dd2d6c75..322bcfce0737 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -196,7 +196,7 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int * attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0; other_half_scan: inet_get_local_port_range(net, &low, &high); - high++; /* [32768, 60999] -> [32768, 61000[ */ + high++; /* [49152, 60999] -> [49152, 61000[ */ if (high - low < 4) attempt_half = 0; if (attempt_half) { diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 239e54474b65..547b95a4891a 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -695,7 +695,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, l3mdev = inet_sk_bound_l3mdev(sk); inet_get_local_port_range(net, &low, &high); - high++; /* [32768, 60999] -> [32768, 61000[ */ + high++; /* [49152, 60999] -> [49152, 61000[ */ remaining = high - low; if (likely(remaining > 1)) remaining &= ~1U;