121 lines
3.7 KiB
Diff
121 lines
3.7 KiB
Diff
From 699a8adb3553e2a7fb5930e1f962e2ef6d6f4104 Mon Sep 17 00:00:00 2001
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From: Johannes Berg <johannes.berg@intel.com>
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Date: Wed, 27 Jan 2016 13:41:34 +0100
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Subject: [PATCH 1/2] wext: fix message delay/ordering
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Beniamino reported that he was getting an RTM_NEWLINK message for a
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given interface, after the RTM_DELLINK for it. It turns out that the
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message is a wireless extensions message, which was sent because the
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interface had been connected and disconnection while it was deleted
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caused a wext message.
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For its netlink messages, wext uses RTM_NEWLINK, but the message is
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without all the regular rtnetlink attributes, so "ip monitor link"
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prints just rudimentary information:
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5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default
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link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff
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Deleted 5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default
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link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff
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5: wlan1: <BROADCAST,MULTICAST,UP>
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link/ether
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(from my hwsim reproduction)
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This can cause userspace to get confused since it doesn't expect an
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RTM_NEWLINK message after RTM_DELLINK.
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The reason for this is that wext schedules a worker to send out the
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messages, and the scheduling delay can cause the messages to get out
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to userspace in different order.
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To fix this, have wext register a netdevice notifier and flush out
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any pending messages when netdevice state changes. This fixes any
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ordering whenever the original message wasn't sent by a notifier
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itself.
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Cc: stable@vger.kernel.org
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Reported-by: Beniamino Galvani <bgalvani@redhat.com>
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Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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---
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net/wireless/wext-core.c | 49 ++++++++++++++++++++++++++++++++++++++----------
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1 file changed, 39 insertions(+), 10 deletions(-)
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diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
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index c8717c1d082e..5f429637efff 100644
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--- a/net/wireless/wext-core.c
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+++ b/net/wireless/wext-core.c
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@@ -342,6 +342,39 @@ static const int compat_event_type_size[] = {
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/* IW event code */
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+static void wireless_nlevent_flush(void)
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+{
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+ struct sk_buff *skb;
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+ struct net *net;
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+
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+ ASSERT_RTNL();
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+
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+ for_each_net(net) {
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+ while ((skb = skb_dequeue(&net->wext_nlevents)))
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+ rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL,
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+ GFP_KERNEL);
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+ }
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+}
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+
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+static int wext_netdev_notifier_call(struct notifier_block *nb,
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+ unsigned long state, void *ptr)
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+{
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+ /*
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+ * When a netdev changes state in any way, flush all pending messages
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+ * to avoid them going out in a strange order, e.g. RTM_NEWLINK after
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+ * RTM_DELLINK, or with IFF_UP after without IFF_UP during dev_close()
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+ * or similar - all of which could otherwise happen due to delays from
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+ * schedule_work().
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+ */
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+ wireless_nlevent_flush();
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+
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+ return NOTIFY_OK;
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+}
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+
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+static struct notifier_block wext_netdev_notifier = {
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+ .notifier_call = wext_netdev_notifier_call,
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+};
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+
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static int __net_init wext_pernet_init(struct net *net)
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{
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skb_queue_head_init(&net->wext_nlevents);
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@@ -360,6 +393,11 @@ static struct pernet_operations wext_pernet_ops = {
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static int __init wireless_nlevent_init(void)
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{
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+ int err = register_netdevice_notifier(&wext_netdev_notifier);
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+
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+ if (err)
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+ return err;
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+
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return register_pernet_subsys(&wext_pernet_ops);
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}
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@@ -368,17 +406,8 @@ subsys_initcall(wireless_nlevent_init);
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/* Process events generated by the wireless layer or the driver. */
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static void wireless_nlevent_process(struct work_struct *work)
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{
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- struct sk_buff *skb;
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- struct net *net;
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-
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rtnl_lock();
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-
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- for_each_net(net) {
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- while ((skb = skb_dequeue(&net->wext_nlevents)))
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- rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL,
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- GFP_KERNEL);
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- }
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-
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+ wireless_nlevent_flush();
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rtnl_unlock();
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}
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--
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2.5.0
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