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authorMathy Vanhoef <Mathy.Vanhoef@kuleuven.be>2021-05-11 21:02:42 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-06-03 09:38:03 +0300
commit3c919823e4cad7bdc2c92b0dd3b4dc463c9315bd (patch)
tree95fd31eb84c319dff427671e57abc749a0b3a91e /net/mac80211
parentd4a6f0df89cbc105ab0cbe9fd2dda64756684451 (diff)
downloadlinux-3c919823e4cad7bdc2c92b0dd3b4dc463c9315bd.tar.xz
mac80211: assure all fragments are encrypted
commit 965a7d72e798eb7af0aa67210e37cf7ecd1c9cad upstream. Do not mix plaintext and encrypted fragments in protected Wi-Fi networks. This fixes CVE-2020-26147. Previously, an attacker was able to first forward a legitimate encrypted fragment towards a victim, followed by a plaintext fragment. The encrypted and plaintext fragment would then be reassembled. For further details see Section 6.3 and Appendix D in the paper "Fragment and Forge: Breaking Wi-Fi Through Frame Aggregation and Fragmentation". Because of this change there are now two equivalent conditions in the code to determine if a received fragment requires sequential PNs, so we also move this test to a separate function to make the code easier to maintain. Cc: stable@vger.kernel.org Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be> Link: https://lore.kernel.org/r/20210511200110.30c4394bb835.I5acfdb552cc1d20c339c262315950b3eac491397@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/mac80211')
-rw-r--r--net/mac80211/rx.c23
1 files changed, 12 insertions, 11 deletions
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 9e92e5e2336b..bf100fe67439 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2078,6 +2078,16 @@ ieee80211_reassemble_find(struct ieee80211_sub_if_data *sdata,
return NULL;
}
+static bool requires_sequential_pn(struct ieee80211_rx_data *rx, __le16 fc)
+{
+ return rx->key &&
+ (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
+ ieee80211_has_protected(fc);
+}
+
static ieee80211_rx_result debug_noinline
ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
{
@@ -2122,12 +2132,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
/* This is the first fragment of a new frame. */
entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
rx->seqno_idx, &(rx->skb));
- if (rx->key &&
- (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
- ieee80211_has_protected(fc)) {
+ if (requires_sequential_pn(rx, fc)) {
int queue = rx->security_idx;
/* Store CCMP/GCMP PN so that we can verify that the
@@ -2169,11 +2174,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
u8 pn[IEEE80211_CCMP_PN_LEN], *rpn;
int queue;
- if (!rx->key ||
- (rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP_256 &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP_256))
+ if (!requires_sequential_pn(rx, fc))
return RX_DROP_UNUSABLE;
memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {