[PATCH 07/18] mac80211: check defrag PN against current frame

[Johannes Berg <johannes@xxxxxxxxxxxxxxxx>]

From: Johannes Berg <johannes.berg@xxxxxxxxx>

As pointed out by Mathy Vanhoef, we implement the RX PN check
on fragmented frames incorrectly - we check against the last
received PN prior to the new frame, rather than to the one in
this frame itself.

Prior patches addressed the security issue here, but in order
to be able to reason better about the code, fix it to really
compare against the current frame's PN, not the last stored
one.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
 net/mac80211/ieee80211_i.h | 11 +++++++++--
 net/mac80211/rx.c          |  5 ++---
 net/mac80211/wpa.c         | 13 +++++++++----
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 4c714375bad0..214404a558fb 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -223,8 +223,15 @@ struct ieee80211_rx_data {
 	 */
 	int security_idx;
 
-	u32 tkip_iv32;
-	u16 tkip_iv16;
+	union {
+		struct {
+			u32 iv32;
+			u16 iv16;
+		} tkip;
+		struct {
+			u8 pn[IEEE80211_CCMP_PN_LEN];
+		} ccm_gcm;
+	};
 };
 
 struct ieee80211_csa_settings {
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 7212a1bebd0c..b619c47e1d12 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2308,7 +2308,6 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 	if (entry->check_sequential_pn) {
 		int i;
 		u8 pn[IEEE80211_CCMP_PN_LEN], *rpn;
-		int queue;
 
 		if (!requires_sequential_pn(rx, fc))
 			return RX_DROP_UNUSABLE;
@@ -2323,8 +2322,8 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 			if (pn[i])
 				break;
 		}
-		queue = rx->security_idx;
-		rpn = rx->key->u.ccmp.rx_pn[queue];
+
+		rpn = rx->ccm_gcm.pn;
 		if (memcmp(pn, rpn, IEEE80211_CCMP_PN_LEN))
 			return RX_DROP_UNUSABLE;
 		memcpy(entry->last_pn, pn, IEEE80211_CCMP_PN_LEN);
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 91bf32af55e9..bca47fad5a16 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -3,6 +3,7 @@
  * Copyright 2002-2004, Instant802 Networks, Inc.
  * Copyright 2008, Jouni Malinen <j@xxxxx>
  * Copyright (C) 2016-2017 Intel Deutschland GmbH
+ * Copyright (C) 2020-2021 Intel Corporation
  */
 
 #include <linux/netdevice.h>
@@ -167,8 +168,8 @@ ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
 
 update_iv:
 	/* update IV in key information to be able to detect replays */
-	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
-	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;
+	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip.iv32;
+	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip.iv16;
 
 	return RX_CONTINUE;
 
@@ -294,8 +295,8 @@ ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 					  key, skb->data + hdrlen,
 					  skb->len - hdrlen, rx->sta->sta.addr,
 					  hdr->addr1, hwaccel, rx->security_idx,
-					  &rx->tkip_iv32,
-					  &rx->tkip_iv16);
+					  &rx->tkip.iv32,
+					  &rx->tkip.iv16);
 	if (res != TKIP_DECRYPT_OK)
 		return RX_DROP_UNUSABLE;
 
@@ -553,6 +554,8 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx,
 		}
 
 		memcpy(key->u.ccmp.rx_pn[queue], pn, IEEE80211_CCMP_PN_LEN);
+		if (unlikely(ieee80211_is_frag(hdr)))
+			memcpy(rx->ccm_gcm.pn, pn, IEEE80211_CCMP_PN_LEN);
 	}
 
 	/* Remove CCMP header and MIC */
@@ -781,6 +784,8 @@ ieee80211_crypto_gcmp_decrypt(struct ieee80211_rx_data *rx)
 		}
 
 		memcpy(key->u.gcmp.rx_pn[queue], pn, IEEE80211_GCMP_PN_LEN);
+		if (unlikely(ieee80211_is_frag(hdr)))
+			memcpy(rx->ccm_gcm.pn, pn, IEEE80211_CCMP_PN_LEN);
 	}
 
 	/* Remove GCMP header and MIC */
-- 
2.30.2