From patchwork Tue Aug 4 15:48:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Izabela Bakollari X-Patchwork-Id: 1340899 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=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=MxG/dpyM; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BLfMT58lHz9sPC for ; Wed, 5 Aug 2020 01:49:41 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728842AbgHDPtB (ORCPT ); Tue, 4 Aug 2020 11:49:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725864AbgHDPsz (ORCPT ); Tue, 4 Aug 2020 11:48:55 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4ED3BC06174A; Tue, 4 Aug 2020 08:48:55 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id kq25so30025502ejb.3; Tue, 04 Aug 2020 08:48:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=aHpL707Nss711rXrUizpThLuemDkqB5ODmR6Us/BMpc=; b=MxG/dpyMaF6vYnVh6cmGFs2sWeiZm+D1y5e+wPKRIQHAckDajxPdgAPQWawbopVVZC 731wC5XDRn8ehsL4GKW6TgjYQ3S+Rnl/MRVDB2d3w7KM8hcGjH5s1s49jzGYJLTIfT2L +jPDLE1woC+77z3Pnk4cxhOsNxA+vH1Pvkeaj9Lzu3PXtLlr8kZdtcONi17AkXOqLwoK kY/4EANA3lBd0/8ZRubKxgdaGarZ0XR7g27zO4UGCgJ+g0tI7z99TDlc1U/5U/2CxZSN ktcB8EareRzLEbU+g4P0CLxKgPnsYM4GejeJg954pD5GHK2+ScB3Ye1gWWCT9VFJRoLi mrSw== 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; bh=aHpL707Nss711rXrUizpThLuemDkqB5ODmR6Us/BMpc=; b=dUVy/YswA3Y04gCrh3T+gSlua22Z4R7PN773/Kch9r0EYBHNtbD9ACkJi0Kmstketo Gu77DP2mQl8vrrISJsToeYfskJfJXdETUJZpSmmCASH+2Bq/wDUf4ykNF3NiVXJMECy5 CwkEARdigPvAloqwMdD10bfXwaLIhCFpN4OeEAVPq41ON0W1P385OPCnaxJ9C9I8v6Tl BV886P30w68OUqb5LjL541sjyze/AUIXyzjgrxGwChZ3Jv+cIbm6Mvqr+36HkUoCDVWJ ZFmeCZ5Mf9DVu0XrKr5eHxXsZaqTcfm7/inaf/M8gOQ5XkAm50U3xKftXpsV1uiptU/k Gj1g== X-Gm-Message-State: AOAM532qFVkCu/qIUBGwVEySC2f8GQw6kJTRPPl4ND69P7DxKUysReZL GxLQB9pq1RvCQn240iVdAXI= X-Google-Smtp-Source: ABdhPJx2ys+HLh3jETOmrP6+gdnOSBsONXpK15a0Qi+Y2ZO5ZSSbKWg6FJqq9i71dQgv/BSsF4LqiQ== X-Received: by 2002:a17:907:398:: with SMTP id ss24mr5841408ejb.311.1596556133900; Tue, 04 Aug 2020 08:48:53 -0700 (PDT) Received: from localhost.localdomain ([185.200.214.168]) by smtp.gmail.com with ESMTPSA id m24sm18686780eje.80.2020.08.04.08.48.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2020 08:48:53 -0700 (PDT) From: izabela.bakollari@gmail.com To: nhorman@tuxdriver.com, davem@davemloft.net, kuba@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, izabela.bakollari@gmail.com Subject: [PATCHv2 net-next--in-reply-to=<20200707171515.110818-1-izabela.bakollari@gmail.com>] dropwatch: Support monitoring of dropped frames Date: Tue, 4 Aug 2020 17:48:51 +0200 Message-Id: <20200804154851.44141-1-izabela.bakollari@gmail.com> X-Mailer: git-send-email 2.18.4 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Izabela Bakollari Dropwatch is a utility that monitors dropped frames by having userspace record them over the dropwatch protocol over a file. This augument allows live monitoring of dropped frames using tools like tcpdump. With this feature, dropwatch allows two additional commands (start and stop interface) which allows the assignment of a net_device to the dropwatch protocol. When assinged, dropwatch will clone dropped frames, and receive them on the assigned interface, allowing tools like tcpdump to monitor for them. With this feature, create a dummy ethernet interface (ip link add dev dummy0 type dummy), assign it to the dropwatch kernel subsystem, by using these new commands, and then monitor dropped frames in real time by running tcpdump -i dummy0. Signed-off-by: Izabela Bakollari --- Changes in v2: - protect the dummy ethernet interface from being changed by another thread/cpu --- include/uapi/linux/net_dropmon.h | 3 ++ net/core/drop_monitor.c | 84 ++++++++++++++++++++++++++++++++ 2 files changed, 87 insertions(+) diff --git a/include/uapi/linux/net_dropmon.h b/include/uapi/linux/net_dropmon.h index 67e31f329190..e8e861e03a8a 100644 --- a/include/uapi/linux/net_dropmon.h +++ b/include/uapi/linux/net_dropmon.h @@ -58,6 +58,8 @@ enum { NET_DM_CMD_CONFIG_NEW, NET_DM_CMD_STATS_GET, NET_DM_CMD_STATS_NEW, + NET_DM_CMD_START_IFC, + NET_DM_CMD_STOP_IFC, _NET_DM_CMD_MAX, }; @@ -93,6 +95,7 @@ enum net_dm_attr { NET_DM_ATTR_SW_DROPS, /* flag */ NET_DM_ATTR_HW_DROPS, /* flag */ NET_DM_ATTR_FLOW_ACTION_COOKIE, /* binary */ + NET_DM_ATTR_IFNAME, /* string */ __NET_DM_ATTR_MAX, NET_DM_ATTR_MAX = __NET_DM_ATTR_MAX - 1 diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index 8e33cec9fc4e..781e69876d2f 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include @@ -46,6 +47,7 @@ */ static int trace_state = TRACE_OFF; static bool monitor_hw; +struct net_device *interface; /* net_dm_mutex * @@ -54,6 +56,8 @@ static bool monitor_hw; */ static DEFINE_MUTEX(net_dm_mutex); +static DEFINE_SPINLOCK(interface_lock); + struct net_dm_stats { u64 dropped; struct u64_stats_sync syncp; @@ -255,6 +259,21 @@ static void trace_drop_common(struct sk_buff *skb, void *location) out: spin_unlock_irqrestore(&data->lock, flags); + spin_lock_irqsave(&interface_lock, flags); + if (interface && interface != skb->dev) { + skb = skb_clone(skb, GFP_ATOMIC); + if (skb) { + skb->dev = interface; + spin_unlock_irqrestore(&interface_lock, flags); + netif_receive_skb(skb); + } else { + spin_unlock_irqrestore(&interface_lock, flags); + pr_err("dropwatch: Not enough memory to clone dropped skb\n"); + return; + } + } else { + spin_unlock_irqrestore(&interface_lock, flags); + } } static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) @@ -1315,6 +1334,53 @@ static int net_dm_cmd_trace(struct sk_buff *skb, return -EOPNOTSUPP; } +static int net_dm_interface_start(struct net *net, const char *ifname) +{ + struct net_device *nd = dev_get_by_name(net, ifname); + + if (nd) + interface = nd; + else + return -ENODEV; + + return 0; +} + +static int net_dm_interface_stop(struct net *net, const char *ifname) +{ + dev_put(interface); + interface = NULL; + + return 0; +} + +static int net_dm_cmd_ifc_trace(struct sk_buff *skb, struct genl_info *info) +{ + struct net *net = sock_net(skb->sk); + char ifname[IFNAMSIZ]; + + if (net_dm_is_monitoring()) + return -EBUSY; + + memset(ifname, 0, IFNAMSIZ); + nla_strlcpy(ifname, info->attrs[NET_DM_ATTR_IFNAME], IFNAMSIZ - 1); + + switch (info->genlhdr->cmd) { + case NET_DM_CMD_START_IFC: + if (!interface) + return net_dm_interface_start(net, ifname); + else + return -EBUSY; + case NET_DM_CMD_STOP_IFC: + if (interface) + return net_dm_interface_stop(net, interface->name); + else + return -ENODEV; + } + + return 0; +} + static int net_dm_config_fill(struct sk_buff *msg, struct genl_info *info) { void *hdr; @@ -1503,6 +1569,7 @@ static int dropmon_net_event(struct notifier_block *ev_block, struct net_device *dev = netdev_notifier_info_to_dev(ptr); struct dm_hw_stat_delta *new_stat = NULL; struct dm_hw_stat_delta *tmp; + unsigned long flags; switch (event) { case NETDEV_REGISTER: @@ -1529,6 +1596,12 @@ static int dropmon_net_event(struct notifier_block *ev_block, } } } + spin_lock_irqsave(&interface_lock, flags); + if (interface && interface == dev) { + dev_put(interface); + interface = NULL; + } + spin_unlock_irqrestore(&interface_lock, flags); mutex_unlock(&net_dm_mutex); break; } @@ -1543,6 +1616,7 @@ static const struct nla_policy net_dm_nl_policy[NET_DM_ATTR_MAX + 1] = { [NET_DM_ATTR_QUEUE_LEN] = { .type = NLA_U32 }, [NET_DM_ATTR_SW_DROPS] = {. type = NLA_FLAG }, [NET_DM_ATTR_HW_DROPS] = {. type = NLA_FLAG }, + [NET_DM_ATTR_IFNAME] = {. type = NLA_STRING, .len = IFNAMSIZ }, }; static const struct genl_ops dropmon_ops[] = { @@ -1570,6 +1644,16 @@ static const struct genl_ops dropmon_ops[] = { .cmd = NET_DM_CMD_STATS_GET, .doit = net_dm_cmd_stats_get, }, + { + .cmd = NET_DM_CMD_START_IFC, + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .doit = net_dm_cmd_ifc_trace, + }, + { + .cmd = NET_DM_CMD_STOP_IFC, + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .doit = net_dm_cmd_ifc_trace, + }, }; static int net_dm_nl_pre_doit(const struct genl_ops *ops,