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Subject[PATCH 5.4 098/155] mac80211: drop data frames without key on encrypted links
Date
From: Johannes Berg <johannes.berg@intel.com>

commit a0761a301746ec2d92d7fcb82af69c0a6a4339aa upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/mac80211/debugfs_sta.c | 3 ++-
net/mac80211/key.c | 20 ++++++++++++--------
net/mac80211/sta_info.h | 1 +
net/mac80211/tx.c | 12 +++++++++---
4 files changed, 24 insertions(+), 12 deletions(-)

--- 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
};

--- 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_acc
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
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);
}
--- 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,
};
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -590,10 +590,13 @@ ieee80211_tx_h_select_key(struct ieee802
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 ieee802
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;

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