From patchwork Thu Sep 27 17:58:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 975840 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=brauner.io Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; secure) header.d=brauner.io header.i=@brauner.io header.b="GnMpJu2a"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 42LjHy3wM9z9sCW for ; Fri, 28 Sep 2018 03:59:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728632AbeI1ATF (ORCPT ); Thu, 27 Sep 2018 20:19:05 -0400 Received: from mail-ed1-f67.google.com ([209.85.208.67]:38419 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728525AbeI1ATE (ORCPT ); Thu, 27 Sep 2018 20:19:04 -0400 Received: by mail-ed1-f67.google.com with SMTP id x8-v6so5867857eds.5 for ; Thu, 27 Sep 2018 10:59:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=N3HBINMsThJvaGsXZVmuviY1doyzzZiK7DaUmpkTdJg=; b=GnMpJu2azb+KThJX8c21RCJcJM4B1JfDRQYbRGqxFCmZdHFXOqkHCZ7fqqHjoAjDjW MXYFh7dFwtw9vBheSjLxte67PPkWclnCmgMkg6geqQa646JheT+eCHnnP/4y5JnnccSA WdwpqYihiCXzPxmYw72G6PXsIATFfkTALILkPloL1Z7y7mbdMqfJq4ZFHDgf1j57/y5M Nia/s5j8+/CkXm9nHWCvs6VcctTAqBrDnkw5lHjVlPtqtTDErprJREMfWY4pcX53PCSW tKuQUypEc5/sTCrS72bj0dxZkTZp+EzLuxEkCKdQHL1ku7j0KLhBWO9CX1jP8fq3qd92 Fjdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=N3HBINMsThJvaGsXZVmuviY1doyzzZiK7DaUmpkTdJg=; b=CLS/ZWBLgPD51jpKWuIAK+fOTTN7et9b1DIaXqGGxVzEooDsRLnVEEGgBRb3qZE081 7uOVTvyGpXG3K7ik0WIKAx/U7f5P7cnIEuASBb28Y03Ya4VqpcEak9FD0DdYB5ZchZwB GgBz+sO8xNpP2KHgScha84m3sc3raLeVaVkrdh0mB6sdX35L1WhF+dQi352lnfF6PNJJ w0SK1bVPOVGaMj6nBS04rLXzxZygiE7BdcWXv+5gYafbP4e6SU51433O8nnt9vL/+lvK D30flm34uEGDz+f2U1efcsVT3GAfWcGya3XmjhHtSXQA7kvZMiKPyPquQ2zOiHlZ1611 SmEw== X-Gm-Message-State: ABuFfojnzxQ8Hkts1Ee4KY5wcgLYhbBPMRJqL8khcbfKbOMOzmbQo196 sELEHge3zonVheywGsXqTV/z2A== X-Google-Smtp-Source: ACcGV63/DU5jGBVX4lkJfJn98sNJkGkCEXWVLKy70GniZcMXdX2jeXwwWK8QcHjo2ZlZHtvngKqwwQ== X-Received: by 2002:a50:a705:: with SMTP id h5-v6mr19831560edc.162.1538071176974; Thu, 27 Sep 2018 10:59:36 -0700 (PDT) Received: from localhost.localdomain (fa-padur-binz.ediscom.de. [212.204.40.18]) by smtp.gmail.com with ESMTPSA id a9-v6sm1532606edi.26.2018.09.27.10.59.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Sep 2018 10:59:36 -0700 (PDT) From: Christian Brauner To: jbenc@redhat.com, davem@davemloft.net, dsahern@gmail.com, stephen@networkplumber.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Christian Brauner Subject: [PATCH net-next 4/7] decnet: add RTM_GETADDR2 Date: Thu, 27 Sep 2018 19:58:54 +0200 Message-Id: <20180927175857.3511-5-christian@brauner.io> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180927175857.3511-1-christian@brauner.io> References: <20180927175857.3511-1-christian@brauner.io> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Various userspace programs (e.g. iproute2) have sent RTM_GETADDR requests with struct ifinfomsg. This is wrong and should have been struct ifaddrmsg all along as mandated by the manpages. However, dump requests so far didn't parse the netlink message that was sent and succeeded even when a wrong struct was passed along. Currently, the message is parsed under the assumption that the correct struct ifaddrmsg is sent down. If the parsing fails the kernel will still fulfill the request to preserve backwards compatability but a rate-limited message that there were leftover bytes after parsing the message is recorded in dmesg. It has been argued that this is unacceptable [1]. But various new features that got and will get added to RTM_GETADDR make it necessary to definitely know what header was passed along. This is currently not possible without resorting to (likely unreliable) hacks such as introducing a nested attribute that ensures that RTM_GETADDR which pass along properties such as IFA_TARGET_NETNSID always exceed RTM_GETADDR requests that send down the wrong struct ifinfomsg [2]. Basically, multiple approaches to solve this have been shut down. Furthermore, the API expressed via RTM_GETADDR is apparently frozen [3] so the wiggle room at this point seems very much zero. The correct solution at this point seems to me to introduce a new RTM_GETADDR2 request. This way we can parse the message and fail hard if the struct is not struct ifaddrmsg and can safely extend it in the future. Userspace tools that rely on the buggy RTM_GETADDR API will still keep working without even having to see any log messages and new userspace tools that want to make user of new features can make use of the new RTM_GETADDR2 requests. [1]: https://lists.openwall.net/netdev/2018/09/25/59 [2]: https://lists.openwall.net/netdev/2018/09/25/75 [3]: https://lists.openwall.net/netdev/2018/09/26/166 Signed-off-by: Christian Brauner Cc: David Ahern Cc: Jiri Benc Cc: Stephen Hemminger --- net/decnet/dn_dev.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c index d0b3e69c6b39..8da6ca154c08 100644 --- a/net/decnet/dn_dev.c +++ b/net/decnet/dn_dev.c @@ -738,10 +738,12 @@ static void dn_ifaddr_notify(int event, struct dn_ifaddr *ifa) rtnl_set_sk_err(&init_net, RTNLGRP_DECnet_IFADDR, err); } -static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb) +static int dn_nl_dump_ifaddr_common(struct sk_buff *skb, + struct netlink_callback *cb, int rtm_type) { struct net *net = sock_net(skb->sk); - int idx, dn_idx = 0, skip_ndevs, skip_naddr; + int err, idx, dn_idx = 0, skip_ndevs, skip_naddr; + struct nlattr *tb[IFA_MAX+1]; struct net_device *dev; struct dn_dev *dn_db; struct dn_ifaddr *ifa; @@ -749,6 +751,13 @@ static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb) if (!net_eq(net, &init_net)) return 0; + if (rtm_type == RTM_GETADDR2) { + err = nlmsg_parse(cb->nlh, sizeof(struct ifaddrmsg), tb, IFA_MAX, + dn_ifa_policy, NULL); + if (err < 0) + return err; + } + skip_ndevs = cb->args[0]; skip_naddr = cb->args[1]; @@ -787,6 +796,16 @@ static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb) return skb->len; } +static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb) +{ + return dn_nl_dump_ifaddr_common(skb, cb, RTM_GETADDR); +} + +static int dn_nl_dump_ifaddr2(struct sk_buff *skb, struct netlink_callback *cb) +{ + return dn_nl_dump_ifaddr_common(skb, cb, RTM_GETADDR2); +} + static int dn_dev_get_first(struct net_device *dev, __le16 *addr) { struct dn_dev *dn_db; @@ -1410,6 +1429,8 @@ void __init dn_dev_init(void) dn_nl_deladdr, NULL, 0); rtnl_register_module(THIS_MODULE, PF_DECnet, RTM_GETADDR, NULL, dn_nl_dump_ifaddr, 0); + rtnl_register_module(THIS_MODULE, PF_DECnet, RTM_GETADDR2, + NULL, dn_nl_dump_ifaddr2, 0); proc_create_seq("decnet_dev", 0444, init_net.proc_net, &dn_dev_seq_ops);