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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F0B3C4332F for ; Wed, 23 Nov 2022 12:58:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238564AbiKWM6x (ORCPT ); Wed, 23 Nov 2022 07:58:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238734AbiKWM5Y (ORCPT ); Wed, 23 Nov 2022 07:57:24 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83A1B903AD; Wed, 23 Nov 2022 04:46:03 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id ADB94B81F40; Wed, 23 Nov 2022 12:45:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4AE4DC433B5; Wed, 23 Nov 2022 12:45:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669207547; bh=Uudvv/eYZ5Is7IV34IZjrizxRmx39zAx9iz/aM6iyTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LEPvjTgLPq8OdZALu/ADI17Qi0IFDRq9EcKC2D11clWP+b69cYScFJFkjDFTR/TdK N4vfaGOgmMmfRj8oOEitiFEHKu/q+zpnqYdXmKC1Nyl/p/eYmExWCj0GBqbd2ggQjA 1tfqL3TDCC0C/OaX5dixUXtRovP+iQInMog4nZvfJ2SkBwaCojFyq4hTUvnnxK/JDT 49IluFDKDHYFaX6Zw19G66/vzMkjIKCsHgzUkxkvmNFYyW+Udcw9d9qzgX+xp9Db08 yYPyol5D3h01/jNM0MwhSljMbLqtAaLNZkLdqqxePXp1CAGOtanQcYNmu3SgIZj1Z4 j8trZhXuB6nkg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Gleb Mazovetskiy , Kuniyuki Iwashima , "David S . Miller" , Sasha Levin , yoshfuji@linux-ipv6.org, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 4/5] tcp: configurable source port perturb table size Date: Wed, 23 Nov 2022 07:45:36 -0500 Message-Id: <20221123124540.266772-4-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221123124540.266772-1-sashal@kernel.org> References: <20221123124540.266772-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Gleb Mazovetskiy [ Upstream commit aeac4ec8f46d610a10adbaeff5e2edf6a88ffc62 ] On embedded systems with little memory and no relevant security concerns, it is beneficial to reduce the size of the table. Reducing the size from 2^16 to 2^8 saves 255 KiB of kernel RAM. Makes the table size configurable as an expert option. The size was previously increased from 2^8 to 2^16 in commit 4c2c8f03a5ab ("tcp: increase source port perturb table to 2^16"). Signed-off-by: Gleb Mazovetskiy Reviewed-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/Kconfig | 10 ++++++++++ net/ipv4/inet_hashtables.c | 10 +++++----- 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index 4d265d4a0dbe..29be5bcbe7ac 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -371,6 +371,16 @@ config INET_IPCOMP If unsure, say Y. +config INET_TABLE_PERTURB_ORDER + int "INET: Source port perturbation table size (as power of 2)" if EXPERT + default 16 + help + Source port perturbation table size (as power of 2) for + RFC 6056 3.3.4. Algorithm 4: Double-Hash Port Selection Algorithm. + + The default is almost always what you want. + Only change this if you know what you are doing. + config INET_XFRM_TUNNEL tristate select INET_TUNNEL diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index db47e1c407d9..9958850b6cee 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -541,13 +541,13 @@ EXPORT_SYMBOL_GPL(inet_unhash); * Note that we use 32bit integers (vs RFC 'short integers') * because 2^16 is not a multiple of num_ephemeral and this * property might be used by clever attacker. + * * RFC claims using TABLE_LENGTH=10 buckets gives an improvement, though - * attacks were since demonstrated, thus we use 65536 instead to really - * give more isolation and privacy, at the expense of 256kB of kernel - * memory. + * attacks were since demonstrated, thus we use 65536 by default instead + * to really give more isolation and privacy, at the expense of 256kB + * of kernel memory. */ -#define INET_TABLE_PERTURB_SHIFT 16 -#define INET_TABLE_PERTURB_SIZE (1 << INET_TABLE_PERTURB_SHIFT) +#define INET_TABLE_PERTURB_SIZE (1 << CONFIG_INET_TABLE_PERTURB_ORDER) static u32 *table_perturb; int __inet_hash_connect(struct inet_timewait_death_row *death_row, -- 2.35.1