diff mbox series

[SRU,Focal/linux-oem-5.6,Focal,9/16] mac80211: drop A-MSDUs on old ciphers

Message ID 20210525174625.69071-11-cascardo@canonical.com
State Accepted
Headers show
Series [SRU,Hirsute,Groovy,Focal/linux-oem-5.10,Focal/linux-oem-5.6,Focal,01/16] mac80211: assure all fragments are encrypted | expand

Commit Message

Thadeu Lima de Souza Cascardo May 25, 2021, 5:46 p.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

With old ciphers (WEP and TKIP) we shouldn't be using A-MSDUs
since A-MSDUs are only supported if we know that they are, and
the only practical way for that is HT support which doesn't
support old ciphers.

However, we would normally accept them anyway. Since we check
the MMIC before deaggregating A-MSDUs, and the A-MSDU bit in
the QoS header is not protected in TKIP (or WEP), this enables
attacks similar to CVE-2020-24588. To prevent that, drop A-MSDUs
completely with old ciphers.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210511200110.076543300172.I548e6e71f1ee9cad4b9a37bf212ae7db723587aa@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
(backported from commit 270032a2a9c4535799736142e1e7c413ca7b836e)
[cascardo: small conflicts on copyright headers, picked latest dates]
CVE-2020-24588
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 net/mac80211/rx.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index dbd8ce019f23..92cb11de8c62 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -6,7 +6,7 @@ 
  * Copyright 2007-2010	Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
  * Copyright(c) 2015 - 2017 Intel Deutschland GmbH
- * Copyright (C) 2018-2019 Intel Corporation
+ * Copyright (C) 2018-2021 Intel Corporation
  */
 
 #include <linux/jiffies.h>
@@ -2730,6 +2730,23 @@  ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
 	if (is_multicast_ether_addr(hdr->addr1))
 		return RX_DROP_UNUSABLE;
 
+	if (rx->key) {
+		/*
+		 * We should not receive A-MSDUs on pre-HT connections,
+		 * and HT connections cannot use old ciphers. Thus drop
+		 * them, as in those cases we couldn't even have SPP
+		 * A-MSDUs or such.
+		 */
+		switch (rx->key->conf.cipher) {
+		case WLAN_CIPHER_SUITE_WEP40:
+		case WLAN_CIPHER_SUITE_WEP104:
+		case WLAN_CIPHER_SUITE_TKIP:
+			return RX_DROP_UNUSABLE;
+		default:
+			break;
+		}
+	}
+
 	return __ieee80211_rx_h_amsdu(rx, 0);
 }