mirror of
https://github.com/openwrt/openwrt.git
synced 2025-01-05 05:24:20 +00:00
88 lines
2.9 KiB
Diff
88 lines
2.9 KiB
Diff
|
From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
|
||
|
|
Date: Tue, 11 May 2021 20:02:43 +0200
|
||
|
|
Subject: [PATCH] mac80211: prevent mixed key and fragment cache attacks
|
||
|
|
|
||
|
|
Simultaneously prevent mixed key attacks (CVE-2020-24587) and fragment
|
||
|
|
cache attacks (CVE-2020-24586). This is accomplished by assigning a
|
||
|
|
unique color to every key (per interface) and using this to track which
|
||
|
|
key was used to decrypt a fragment. When reassembling frames, it is
|
||
|
|
now checked whether all fragments were decrypted using the same key.
|
||
|
|
|
||
|
|
To assure that fragment cache attacks are also prevented, the ID that is
|
||
|
|
assigned to keys is unique even over (re)associations and (re)connects.
|
||
|
|
This means fragments separated by a (re)association or (re)connect will
|
||
|
|
not be reassembled. Because mac80211 now also prevents the reassembly of
|
||
|
|
mixed encrypted and plaintext fragments, all cache attacks are prevented.
|
||
|
|
|
||
|
|
Cc: stable@vger.kernel.org
|
||
|
|
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
|
||
|
|
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
|
||
|
|
---
|
||
|
|
|
||
|
|
--- a/net/mac80211/ieee80211_i.h
|
||
|
|
+++ b/net/mac80211/ieee80211_i.h
|
||
|
|
@@ -97,6 +97,7 @@ struct ieee80211_fragment_entry {
|
||
|
|
u8 rx_queue;
|
||
|
|
bool check_sequential_pn; /* needed for CCMP/GCMP */
|
||
|
|
u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
|
||
|
|
+ unsigned int key_color;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
--- a/net/mac80211/key.c
|
||
|
|
+++ b/net/mac80211/key.c
|
||
|
|
@@ -799,6 +799,7 @@ int ieee80211_key_link(struct ieee80211_
|
||
|
|
struct ieee80211_sub_if_data *sdata,
|
||
|
|
struct sta_info *sta)
|
||
|
|
{
|
||
|
|
+ static atomic_t key_color = ATOMIC_INIT(0);
|
||
|
|
struct ieee80211_key *old_key;
|
||
|
|
int idx = key->conf.keyidx;
|
||
|
|
bool pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
|
||
|
|
@@ -850,6 +851,12 @@ int ieee80211_key_link(struct ieee80211_
|
||
|
|
key->sdata = sdata;
|
||
|
|
key->sta = sta;
|
||
|
|
|
||
|
|
+ /*
|
||
|
|
+ * Assign a unique ID to every key so we can easily prevent mixed
|
||
|
|
+ * key and fragment cache attacks.
|
||
|
|
+ */
|
||
|
|
+ key->color = atomic_inc_return(&key_color);
|
||
|
|
+
|
||
|
|
increment_tailroom_need_count(sdata);
|
||
|
|
|
||
|
|
ret = ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
|
||
|
|
--- a/net/mac80211/key.h
|
||
|
|
+++ b/net/mac80211/key.h
|
||
|
|
@@ -128,6 +128,8 @@ struct ieee80211_key {
|
||
|
|
} debugfs;
|
||
|
|
#endif
|
||
|
|
|
||
|
|
+ unsigned int color;
|
||
|
|
+
|
||
|
|
/*
|
||
|
|
* key config, must be last because it contains key
|
||
|
|
* material as variable length member
|
||
|
|
--- a/net/mac80211/rx.c
|
||
|
|
+++ b/net/mac80211/rx.c
|
||
|
|
@@ -2265,6 +2265,7 @@ ieee80211_rx_h_defragment(struct ieee802
|
||
|
|
* next fragment has a sequential PN value.
|
||
|
|
*/
|
||
|
|
entry->check_sequential_pn = true;
|
||
|
|
+ entry->key_color = rx->key->color;
|
||
|
|
memcpy(entry->last_pn,
|
||
|
|
rx->key->u.ccmp.rx_pn[queue],
|
||
|
|
IEEE80211_CCMP_PN_LEN);
|
||
|
|
@@ -2302,6 +2303,11 @@ ieee80211_rx_h_defragment(struct ieee802
|
||
|
|
|
||
|
|
if (!requires_sequential_pn(rx, fc))
|
||
|
|
return RX_DROP_UNUSABLE;
|
||
|
|
+
|
||
|
|
+ /* Prevent mixed key and fragment cache attacks */
|
||
|
|
+ if (entry->key_color != rx->key->color)
|
||
|
|
+ return RX_DROP_UNUSABLE;
|
||
|
|
+
|
||
|
|
memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
|
||
|
|
for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {
|
||
|
|
pn[i]++;
|