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 48183CCA479 for ; Wed, 13 Jul 2022 23:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231551AbiGMXkw (ORCPT ); Wed, 13 Jul 2022 19:40:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231450AbiGMXkr (ORCPT ); Wed, 13 Jul 2022 19:40:47 -0400 Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0A30509C1; Wed, 13 Jul 2022 16:40:46 -0700 (PDT) Received: by mail-pj1-x1030.google.com with SMTP id o3-20020a17090a744300b001ef8f7f3dddso597165pjk.3; Wed, 13 Jul 2022 16:40:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=wCM0UDHUVihBgY7YWogvcLCrLbNF9p6xLuztOGFMvkI=; b=NRoJ+UDhRHy76a4NDta3han9YBZ/XI48D458cpbWyqf78sPEzf7J11OD2gxerrpeIH u0ew6cdFtZ/kpyL0J7FgaGDETdPeNXDLFGnm3Barq78fwAMDo45SQxXO/rP3v8I5nKAJ RdXhvR40A/vJYjM/JHb9rfGuKOi3RZd/SqIKqlURToGI5c4t32lF3zXcg/8nRt9uIAYY 7GrYLhjWMRmPxZ1ATrayMdkSF4nHkJzm8yEdn8ZEH2D5Xnj+PlMQXPaZZKghirEr8/IG u8a5RrUm6LLcbWmp7iyXGW4WdHIS/3eNsOVRpPt+Ds2KV65XwOVwykUn/3u+FyVLiTNH 0+MA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=wCM0UDHUVihBgY7YWogvcLCrLbNF9p6xLuztOGFMvkI=; b=55bjfnGa9F+btT5xXY7ManCJcDWhmEPiQSqkp/jFvERahiCayiPqyIUvBqdT7dCXYZ KlcYXF4vVslpHmNYqMZ1PqFS8AHKeUMDmvxLmyXDnm50n0Csteox+hacpERdp4UNWrW5 +Kny1STuKI9MDQ9Iuq/ic5tqWYEuW0B5vJzKF8tB8TocP9JzIdBTx3titky8HH9oZDnH avru4fLeEdHbf5lPpeUay+1kELKznh4vqB9l3kE6iwlDa2fNpAHvsagnovceDfezIsNU owEKaa8FIosi9op2t9fUQvWTzmweKLaQuIWERt5jqYUPxUYKuhG8+VzD5cyRjPxbAS2/ X86Q== X-Gm-Message-State: AJIora/rxcqp8cNTJxViScZgsJChpglLR/3ElI1fJEb3DMMSMl3rMJEg LHY6ha5A0R3aCthSnqeY0BZ0ZXOXtkZH/jrNDTI= X-Google-Smtp-Source: AGRyM1vxMiPvZqkn2A8ffZQTH6vgXFh3gLcPVtDqEqjmO8KcOngWL/INdw62fpEVTVakBqwNasBDwg== X-Received: by 2002:a17:902:7d92:b0:16c:54a4:bb2f with SMTP id a18-20020a1709027d9200b0016c54a4bb2fmr5828227plm.158.1657755645829; Wed, 13 Jul 2022 16:40:45 -0700 (PDT) Received: from localhost.localdomain ([64.141.80.140]) by smtp.gmail.com with ESMTPSA id 188-20020a6216c5000000b005286a4ca9c8sm87653pfw.211.2022.07.13.16.40.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Jul 2022 16:40:45 -0700 (PDT) From: Jaehee Park To: netdev@vger.kernel.org Cc: davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, dsahern@gmail.com, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, shuah@kernel.org, linux-kernel@vger.kernel.org, aajith@arista.com, roopa@nvidia.com, roopa.prabhu@gmail.com, aroulin@nvidia.com, sbrivio@redhat.com, jhpark1013@gmail.com Subject: [PATCH v3 net-next 1/3] net: ipv4: new arp_accept option to accept garp only if in-network Date: Wed, 13 Jul 2022 16:40:47 -0700 Message-Id: <93cfe14597ec1205f61366b9902876287465f1cd.1657755189.git.jhpark1013@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In many deployments, we want the option to not learn a neighbor from garp if the src ip is not in the same subnet as an address configured on the interface that received the garp message. net.ipv4.arp_accept sysctl is currently used to control creation of a neigh from a received garp packet. This patch adds a new option '2' to net.ipv4.arp_accept which extends option '1' by including the subnet check. Signed-off-by: Jaehee Park Suggested-by: Roopa Prabhu --- Documentation/networking/ip-sysctl.rst | 9 ++++++--- include/linux/inetdevice.h | 2 +- net/ipv4/arp.c | 24 ++++++++++++++++++++++-- 3 files changed, 29 insertions(+), 6 deletions(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 4c8bbf5acfd1..5c017fc1e24d 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1633,12 +1633,15 @@ arp_notify - BOOLEAN or hardware address changes. == ========================================================== -arp_accept - BOOLEAN - Define behavior for gratuitous ARP frames who's IP is not - already present in the ARP table: +arp_accept - INTEGER + Define behavior for accepting gratuitous ARP (garp) frames from devices + that are not already present in the ARP table: - 0 - don't create new entries in the ARP table - 1 - create new entries in the ARP table + - 2 - create new entries only if the source IP address is in the same + subnet as an address configured on the interface that received the + garp message. Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on. diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h index ead323243e7b..ddb27fc0ee8c 100644 --- a/include/linux/inetdevice.h +++ b/include/linux/inetdevice.h @@ -131,7 +131,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev) IN_DEV_ORCONF((in_dev), IGNORE_ROUTES_WITH_LINKDOWN) #define IN_DEV_ARPFILTER(in_dev) IN_DEV_ORCONF((in_dev), ARPFILTER) -#define IN_DEV_ARP_ACCEPT(in_dev) IN_DEV_ORCONF((in_dev), ARP_ACCEPT) +#define IN_DEV_ARP_ACCEPT(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ACCEPT) #define IN_DEV_ARP_ANNOUNCE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE) #define IN_DEV_ARP_IGNORE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_IGNORE) #define IN_DEV_ARP_NOTIFY(in_dev) IN_DEV_MAXCONF((in_dev), ARP_NOTIFY) diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index af2f12ffc9ca..87c7e3fc5197 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -429,6 +429,26 @@ static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) return !inet_confirm_addr(net, in_dev, sip, tip, scope); } +static int arp_accept(struct in_device *in_dev, __be32 sip) +{ + struct net *net = dev_net(in_dev->dev); + int scope = RT_SCOPE_LINK; + + switch (IN_DEV_ARP_ACCEPT(in_dev)) { + case 0: /* Don't create new entries from garp */ + return 0; + case 1: /* Create new entries from garp */ + return 1; + case 2: /* Create a neighbor in the arp table only if sip + * is in the same subnet as an address configured + * on the interface that received the garp message + */ + return !!inet_confirm_addr(net, in_dev, sip, 0, scope); + default: + return 0; + } +} + static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) { struct rtable *rt; @@ -868,12 +888,12 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) n = __neigh_lookup(&arp_tbl, &sip, dev, 0); addr_type = -1; - if (n || IN_DEV_ARP_ACCEPT(in_dev)) { + if (n || arp_accept(in_dev, sip)) { is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, sip, tip, sha, tha); } - if (IN_DEV_ARP_ACCEPT(in_dev)) { + if (arp_accept(in_dev, sip)) { /* Unsolicited ARP is not accepted by default. It is possible, that this option should be enabled for some devices (strip is candidate) -- 2.30.2