mac80211: drop data frames without key on encrypted links

If we know that we have an encrypted link (based on having had
a key configured for TX in the past) then drop all data frames
in the key selection handler if there's no key anymore.

This fixes an issue with mac80211 internal TXQs - there we can
buffer frames for an encrypted link, but then if the key is no
longer there when they're dequeued, the frames are sent without
encryption. This happens if a station is disconnected while the
frames are still on the TXQ.

Detecting that a link should be encrypted based on a first key
having been configured for TX is fine as there are no use cases
for a connection going from with encryption to no encryption.
With extended key IDs, however, there is a case of having a key
configured for only decryption, so we can't just trigger this
behaviour on a key being configured.

Cc: stable@vger.kernel.org
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200326150855.6865c7f28a14.I9fb1d911b064262d33e33dfba730cdeef83926ca@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index c80b1e1..3419ed6 100644 (file)
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -5,7 +5,7 @@
  * Copyright 2007      Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
  * Copyright(c) 2016 Intel Deutschland GmbH
- * Copyright (C) 2018 - 2019 Intel Corporation
+ * Copyright (C) 2018 - 2020 Intel Corporation
  */
 
 #include <linux/debugfs.h>
@@ -78,6 +78,7 @@ static const char * const sta_flag_names[] = {
        FLAG(MPSP_OWNER),
        FLAG(MPSP_RECIPIENT),
        FLAG(PS_DELIVER),
+       FLAG(USES_ENCRYPTION),
 #undef FLAG
 };
 

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 0f889b9..efc1acc 100644 (file)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -6,7 +6,7 @@
  * Copyright 2007-2008 Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
  * Copyright 2015-2017 Intel Deutschland GmbH
- * Copyright 2018-2019  Intel Corporation
+ * Copyright 2018-2020  Intel Corporation
  */
 
 #include <linux/if_ether.h>
@@ -262,22 +262,29 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
                          sta ? sta->sta.addr : bcast_addr, ret);
 }
 
-int ieee80211_set_tx_key(struct ieee80211_key *key)
+static int _ieee80211_set_tx_key(struct ieee80211_key *key, bool force)
 {
        struct sta_info *sta = key->sta;
        struct ieee80211_local *local = key->local;
 
        assert_key_lock(local);
 
+       set_sta_flag(sta, WLAN_STA_USES_ENCRYPTION);
+
        sta->ptk_idx = key->conf.keyidx;
 
-       if (!ieee80211_hw_check(&local->hw, AMPDU_KEYBORDER_SUPPORT))
+       if (force || !ieee80211_hw_check(&local->hw, AMPDU_KEYBORDER_SUPPORT))
                clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
        ieee80211_check_fast_xmit(sta);
 
        return 0;
 }
 
+int ieee80211_set_tx_key(struct ieee80211_key *key)
+{
+       return _ieee80211_set_tx_key(key, false);
+}
+
 static void ieee80211_pairwise_rekey(struct ieee80211_key *old,
                                     struct ieee80211_key *new)
 {
@@ -441,11 +448,8 @@ static int ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
                if (pairwise) {
                        rcu_assign_pointer(sta->ptk[idx], new);
                        if (new &&
-                           !(new->conf.flags & IEEE80211_KEY_FLAG_NO_AUTO_TX)) {
-                               sta->ptk_idx = idx;
-                               clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
-                               ieee80211_check_fast_xmit(sta);
-                       }
+                           !(new->conf.flags & IEEE80211_KEY_FLAG_NO_AUTO_TX))
+                               _ieee80211_set_tx_key(new, true);
                } else {
                        rcu_assign_pointer(sta->gtk[idx], new);
                }

diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index c00e285..552eed3 100644 (file)
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -98,6 +98,7 @@ enum ieee80211_sta_info_flags {
        WLAN_STA_MPSP_OWNER,
        WLAN_STA_MPSP_RECIPIENT,
        WLAN_STA_PS_DELIVER,
+       WLAN_STA_USES_ENCRYPTION,
 
        NUM_WLAN_STA_FLAGS,
 };

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 87def9c..7dbfb9e 100644 (file)
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -590,10 +590,13 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
 
-       if (unlikely(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT))
+       if (unlikely(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT)) {
                tx->key = NULL;
-       else if (tx->sta &&
-                (key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx])))
+               return TX_CONTINUE;
+       }
+
+       if (tx->sta &&
+           (key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx])))
                tx->key = key;
        else if (ieee80211_is_group_privacy_action(tx->skb) &&
                (key = rcu_dereference(tx->sdata->default_multicast_key)))
@@ -654,6 +657,9 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
                if (!skip_hw && tx->key &&
                    tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
                        info->control.hw_key = &tx->key->conf;
+       } else if (!ieee80211_is_mgmt(hdr->frame_control) && tx->sta &&
+                  test_sta_flag(tx->sta, WLAN_STA_USES_ENCRYPTION)) {
+               return TX_DROP;
        }
 
        return TX_CONTINUE;