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>

6 files changed, 63 insertions, 6 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 96600be..dda0d1a 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -538,12 +538,14 @@ struct ieee80211_if_mesh {
  * @IEEE80211_SDATA_DONT_BRIDGE_PACKETS: bridge packets between
  *	associated stations and deliver multicast frames both
  *	back to wireless media and to the local net stack.
+ * @IEEE80211_SDATA_DISCONNECT_RESUME: Disconnect after resume.
  */
 enum ieee80211_sub_if_data_flags {
 	IEEE80211_SDATA_ALLMULTI		= BIT(0),
 	IEEE80211_SDATA_PROMISC			= BIT(1),
 	IEEE80211_SDATA_OPERATING_GMODE		= BIT(2),
 	IEEE80211_SDATA_DONT_BRIDGE_PACKETS	= BIT(3),
+	IEEE80211_SDATA_DISCONNECT_RESUME	= BIT(4),
 };
 
 /**
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index 86b216b..7d4e31f 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -41,9 +41,11 @@ struct sta_info;
  *
  * @KEY_FLAG_UPLOADED_TO_HARDWARE: Indicates that this key is present
  *	in the hardware for TX crypto hardware acceleration.
+ * @KEY_FLAG_TAINTED: Key is tainted and packets should be dropped.
  */
 enum ieee80211_internal_key_flags {
 	KEY_FLAG_UPLOADED_TO_HARDWARE	= BIT(0),
+	KEY_FLAG_TAINTED		= BIT(1),
 };
 
 enum ieee80211_internal_tkip_state {
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 4b0460a..c99237c 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2052,7 +2052,7 @@ static void ieee80211_sta_timer(unsigned long data)
 }
 
 static void ieee80211_sta_connection_lost(struct ieee80211_sub_if_data *sdata,
-					  u8 *bssid)
+					  u8 *bssid, u8 reason)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
@@ -2070,8 +2070,7 @@ static void ieee80211_sta_connection_lost(struct ieee80211_sub_if_data *sdata,
 	 * but that's not a problem.
 	 */
 	ieee80211_send_deauth_disassoc(sdata, bssid,
-			IEEE80211_STYPE_DEAUTH,
-			WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY,
+			IEEE80211_STYPE_DEAUTH, reason,
 			NULL, true);
 	mutex_lock(&ifmgd->mtx);
 }
@@ -2117,7 +2116,8 @@ void ieee80211_sta_work(struct ieee80211_sub_if_data *sdata)
 					    " AP %pM, disconnecting.\n",
 					    sdata->name, bssid);
 #endif
-				ieee80211_sta_connection_lost(sdata, bssid);
+				ieee80211_sta_connection_lost(sdata, bssid,
+					WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY);
 			}
 		} else if (time_is_after_jiffies(ifmgd->probe_timeout))
 			run_again(ifmgd, ifmgd->probe_timeout);
@@ -2129,7 +2129,8 @@ void ieee80211_sta_work(struct ieee80211_sub_if_data *sdata)
 				    sdata->name,
 				    bssid, probe_wait_ms);
 #endif
-			ieee80211_sta_connection_lost(sdata, bssid);
+			ieee80211_sta_connection_lost(sdata, bssid,
+				WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY);
 		} else if (ifmgd->probe_send_count < max_tries) {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
 			wiphy_debug(local->hw.wiphy,
@@ -2151,7 +2152,8 @@ void ieee80211_sta_work(struct ieee80211_sub_if_data *sdata)
 				    sdata->name,
 				    bssid, probe_wait_ms);
 
-			ieee80211_sta_connection_lost(sdata, bssid);
+			ieee80211_sta_connection_lost(sdata, bssid,
+				WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY);
 		}
 	}
 
@@ -2241,6 +2243,24 @@ void ieee80211_sta_restart(struct ieee80211_sub_if_data *sdata)
 	if (!ifmgd->associated)
 		return;
 
+	if (sdata->flags & IEEE80211_SDATA_DISCONNECT_RESUME) {
+		sdata->flags &= ~IEEE80211_SDATA_DISCONNECT_RESUME;
+		mutex_lock(&ifmgd->mtx);
+		if (ifmgd->associated) {
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+			wiphy_debug(sdata->local->hw.wiphy,
+				    "%s: driver requested disconnect after resume.\n",
+				    sdata->name);
+#endif
+			ieee80211_sta_connection_lost(sdata,
+				ifmgd->associated->bssid,
+				WLAN_REASON_UNSPECIFIED);
+			mutex_unlock(&ifmgd->mtx);
+			return;
+		}
+		mutex_unlock(&ifmgd->mtx);
+	}
+
 	if (test_and_clear_bit(TMR_RUNNING_TIMER, &ifmgd->timers_running))
 		add_timer(&ifmgd->timer);
 	if (test_and_clear_bit(TMR_RUNNING_CHANSW, &ifmgd->timers_running))
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index e6dccc7..fe2c2a7 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1019,6 +1019,9 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
 	}
 
 	if (rx->key) {
+		if (unlikely(rx->key->flags & KEY_FLAG_TAINTED))
+			return RX_DROP_MONITOR;
+
 		rx->key->tx_rx_count++;
 		/* TODO: add threshold stuff again */
 	} else {
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index e8d0d2d..8cb0d2d 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -589,6 +589,9 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 			break;
 		}
 
+		if (unlikely(tx->key && tx->key->flags & KEY_FLAG_TAINTED))
+			return TX_DROP;
+
 		if (!skip_hw && tx->key &&
 		    tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
 			info->control.hw_key = &tx->key->conf;
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 1901320..5bfb80c 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1334,6 +1334,33 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 	return 0;
 }
 
+void ieee80211_resume_disconnect(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata;
+	struct ieee80211_local *local;
+	struct ieee80211_key *key;
+
+	if (WARN_ON(!vif))
+		return;
+
+	sdata = vif_to_sdata(vif);
+	local = sdata->local;
+
+	if (WARN_ON(!local->resuming))
+		return;
+
+	if (WARN_ON(vif->type != NL80211_IFTYPE_STATION))
+		return;
+
+	sdata->flags |= IEEE80211_SDATA_DISCONNECT_RESUME;
+
+	mutex_lock(&local->key_mtx);
+	list_for_each_entry(key, &sdata->key_list, list)
+		key->flags |= KEY_FLAG_TAINTED;
+	mutex_unlock(&local->key_mtx);
+}
+EXPORT_SYMBOL_GPL(ieee80211_resume_disconnect);
+
 static int check_mgd_smps(struct ieee80211_if_managed *ifmgd,
 			  enum ieee80211_smps_mode *smps_mode)
 {