mac80211: allow driver to disconnect after resume

In WoWLAN, devices may use crypto keys for TX/RX
and could also implement GTK rekeying. If the
driver isn't able to retrieve replay counters and
similar information from the device upon resume,
or if the device isn't responsive due to platform
issues, it isn't safe to keep the connection up
as GTK rekey messages from during the sleep time
could be replayed against it.

The only protection against that is disconnecting
from the AP. Modifying mac80211 to do that while
it is resuming would be very complex and invasive
in the case that the driver requires a reconfig,
so do it after it has resumed completely. In that
case, however, packets might be replayed since it
can then only happen after TX/RX are up again, so
mark keys for interfaces that need to disconnect
as "tainted" and drop all packets that are sent
or received with those keys.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 8ff3d8a1377..ea2c8c36477 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -3024,6 +3024,29 @@ void ieee80211_beacon_loss(struct ieee80211_vif *vif);
 void ieee80211_connection_loss(struct ieee80211_vif *vif);
 
 /**
+ * ieee80211_resume_disconnect - disconnect from AP after resume
+ *
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ *
+ * Instructs mac80211 to disconnect from the AP after resume.
+ * Drivers can use this after WoWLAN if they know that the
+ * connection cannot be kept up, for example because keys were
+ * used while the device was asleep but the replay counters or
+ * similar cannot be retrieved from the device during resume.
+ *
+ * Note that due to implementation issues, if the driver uses
+ * the reconfiguration functionality during resume the interface
+ * will still be added as associated first during resume and then
+ * disconnect normally later.
+ *
+ * This function can only be called from the resume callback and
+ * the driver must not be holding any of its own locks while it
+ * calls this function, or at least not any locks it needs in the
+ * key configuration paths (if it supports HW crypto).
+ */
+void ieee80211_resume_disconnect(struct ieee80211_vif *vif);
+
+/**
  * ieee80211_disable_dyn_ps - force mac80211 to temporarily disable dynamic psm
  *
  * @vif: &struct ieee80211_vif pointer from the add_interface callback.