[PATCH 5.12 041/296] mac80211: check defrag PN against current frame

Greg Kroah-Hartman
2021-05-31T16:03:13Z

From: Johannes Berg <johannes.berg@intel.com>

commit bf30ca922a0c0176007e074b0acc77ed345e9990 upstream.

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@vger.kernel.org
Link: https://lore.kernel.org/r/20210511200110.bfbc340ff071.Id0b690e581da7d03d76df90bb0e3fd55930bc8a0@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mac80211/ieee80211_i.h | 11 +++++++++--
net/mac80211/rx.c | 5 ++---
net/mac80211/wpa.c | 13 +++++++++----
3 files changed, 20 insertions(+), 9 deletions(-)

--- 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 {
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2307,7 +2307,6 @@ ieee80211_rx_h_defragment(struct ieee802
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;
@@ -2322,8 +2321,8 @@ ieee80211_rx_h_defragment(struct ieee802
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);
--- 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@w1.fi>
* 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

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 iee
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 iee
}

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 iee
}

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 */