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[PATCH v6] nl80211: Stop scheduled scan if netlink client disappears

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An attribute NL80211_ATTR_SOCKET_OWNER can be set by the scan initiator.
If present, the attribute will cause the scan to be stopped if the client
dies.

Signed-off-by: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>
---
Hi,

v6:
- moved owner netlink port id from cfg80211_sched_scan_request to
  rdev in order to avoid possible races

v5:
- discarded the locking changes in v4
- instead of trying to schedule sched_scan_stop worker from
  struct cfg80211_sched_scan_request, move the worker to wiphy
  as that makes it easier to manage the sched_scan_stop worker.
  There are also one scheduled scan / wiphy so it is also logical
  to do it like this.

v4:
- rtnl locking issues fixed in patch 2

v3:
- backward compatibility define tweaked in patch 1
- added missing signed-off-by:

v2:
- split the patch
- In patch 1, use a generic NL80211_ATTR_SOCKET_OWNER attribute and
  convert the old code that uses NL80211_ATTR_IFACE_SOCKET_OWNER to
  use the new value. A define is provided for backward compatibility.
- Any pending schedule scan stop worker is cancelled when interface is
  taken down in patch 2

Cheers,
Jukka


 include/uapi/linux/nl80211.h |  3 +++
 net/wireless/core.c          | 17 +++++++++++++++++
 net/wireless/core.h          |  2 ++
 net/wireless/nl80211.c       | 14 ++++++++++++++
 4 files changed, 36 insertions(+)

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 185f9c7..5038240 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -1640,6 +1640,9 @@ enum nl80211_commands {
  * @NL80211_ATTR_SOCKET_OWNER: Flag attribute, if set during interface
  *	creation then the new interface will be owned by the netlink socket
  *	that created it and will be destroyed when the socket is closed.
+ *	If set during scheduled scan start then the new scan req will be
+ *	owned by the netlink socket that created it and the scheduled scan will
+ *	be stopped when the socket is closed.
  *
  * @NL80211_ATTR_TDLS_INITIATOR: flag attribute indicating the current end is
  *	the TDLS link initiator.
diff --git a/net/wireless/core.c b/net/wireless/core.c
index a4d2792..6fffcb3 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -320,6 +320,21 @@ static void cfg80211_destroy_iface_wk(struct work_struct *work)
 	rtnl_unlock();
 }
 
+static void cfg80211_sched_scan_stop_wk(struct work_struct *work)
+{
+	struct cfg80211_registered_device *rdev;
+
+	rdev = container_of(work, struct cfg80211_registered_device,
+			   sched_scan_stop_wk);
+
+	rtnl_lock();
+
+	if (rdev->sched_scan_req)
+		__cfg80211_stop_sched_scan(rdev, false);
+
+	rtnl_unlock();
+}
+
 /* exported functions */
 
 struct wiphy *wiphy_new_nm(const struct cfg80211_ops *ops, int sizeof_priv,
@@ -406,6 +421,7 @@ use_default_name:
 	INIT_LIST_HEAD(&rdev->destroy_list);
 	spin_lock_init(&rdev->destroy_list_lock);
 	INIT_WORK(&rdev->destroy_work, cfg80211_destroy_iface_wk);
+	INIT_WORK(&rdev->sched_scan_stop_wk, cfg80211_sched_scan_stop_wk);
 
 #ifdef CONFIG_CFG80211_DEFAULT_PS
 	rdev->wiphy.flags |= WIPHY_FLAG_PS_ON_BY_DEFAULT;
@@ -760,6 +776,7 @@ void wiphy_unregister(struct wiphy *wiphy)
 	flush_work(&rdev->event_work);
 	cancel_delayed_work_sync(&rdev->dfs_update_channels_wk);
 	flush_work(&rdev->destroy_work);
+	flush_work(&rdev->sched_scan_stop_wk);
 
 #ifdef CONFIG_PM
 	if (rdev->wiphy.wowlan_config && rdev->ops->set_wakeup)
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 61ee664..c27615e 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -67,6 +67,8 @@ struct cfg80211_registered_device {
 	unsigned long suspend_at;
 	struct work_struct scan_done_wk;
 	struct work_struct sched_scan_results_wk;
+	struct work_struct sched_scan_stop_wk;
+	u32 sched_scan_owner_nlportid;
 
 	struct genl_info *cur_cmd_info;
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index df447c0..9ed6a34 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5955,6 +5955,9 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 
 	err = rdev_sched_scan_start(rdev, dev, request);
 	if (!err) {
+		if (info->attrs[NL80211_ATTR_SOCKET_OWNER])
+			rdev->sched_scan_owner_nlportid = info->snd_portid;
+
 		rdev->sched_scan_req = request;
 		nl80211_send_sched_scan(rdev, dev,
 					NL80211_CMD_START_SCHED_SCAN);
@@ -12127,6 +12130,11 @@ static int nl80211_netlink_notify(struct notifier_block * nb,
 
 	list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list) {
 		bool schedule_destroy_work = false;
+		bool schedule_scan_stop = false;
+
+		if (rdev->sched_scan_req && notify->portid &&
+		    rdev->sched_scan_owner_nlportid == notify->portid)
+			schedule_scan_stop = true;
 
 		list_for_each_entry_rcu(wdev, &rdev->wdev_list, list) {
 			cfg80211_mlme_unregister_socket(wdev, notify->portid);
@@ -12157,6 +12165,12 @@ static int nl80211_netlink_notify(struct notifier_block * nb,
 				spin_unlock(&rdev->destroy_list_lock);
 				schedule_work(&rdev->destroy_work);
 			}
+		} else if (schedule_scan_stop) {
+			rdev->sched_scan_owner_nlportid = 0;
+
+			if (rdev->ops->sched_scan_stop &&
+			    rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
+				schedule_work(&rdev->sched_scan_stop_wk);
 		}
 	}
 
-- 
1.8.3.1

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