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mac80211: backport fixes for fix for CVE-2017-13080 

Backport two fixes for the fix of CVE-2017-13080, preventing side channel
attacks and making it work for TKIP.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Jonas Gorski 2017-10-26 15:31:15 +02:00
parent 34958c8269
commit 1dcd8e7cf1
2 changed files with 106 additions and 0 deletions
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33
package/kernel/mac80211/patches/328-mac80211-use-constant-time-comparison-with-keys.patch Normal file
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@ -0,0 +1,33 @@
From 2bdd713b92a9cade239d3c7d15205a09f556624d Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 17 Oct 2017 20:32:07 +0200
Subject: [PATCH] mac80211: use constant time comparison with keys
Otherwise we risk leaking information via timing side channel.
Fixes: fdf7cb4185b6 ("mac80211: accept key reinstall without changing anything")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
net/mac80211/key.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/export.h>
#include <net/mac80211.h>
+#include <crypto/algapi.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
@@ -635,7 +636,7 @@ int ieee80211_key_link(struct ieee80211_
* new version of the key to avoid nonce reuse or replay issues.
*/
if (old_key && key->conf.keylen == old_key->conf.keylen &&
- !memcmp(key->conf.key, old_key->conf.key, key->conf.keylen)) {
+ !crypto_memneq(key->conf.key, old_key->conf.key, key->conf.keylen)) {
ieee80211_key_free_unused(key);
ret = 0;
goto out;

73
package/kernel/mac80211/patches/329-mac80211-don-t-compare-TKIP-TX-MIC-key-in-reinstall.patch Normal file
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@ -0,0 +1,73 @@
From cfbb0d90a7abb289edc91833d0905931f8805f12 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Tue, 24 Oct 2017 21:12:13 +0200
Subject: [PATCH] mac80211: don't compare TKIP TX MIC key in reinstall prevention
For the reinstall prevention, the code I had added compares the
whole key. It turns out though that iwlwifi firmware doesn't
provide the TKIP TX MIC key as it's not needed in client mode,
and thus the comparison will always return false.
For client mode, thus always zero out the TX MIC key part before
doing the comparison in order to avoid accepting the reinstall
of the key with identical encryption and RX MIC key, but not the
same TX MIC key (since the supplicant provides the real one.)
Fixes: fdf7cb4185b6 ("mac80211: accept key reinstall without changing anything")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
net/mac80211/key.c | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -610,6 +610,39 @@ void ieee80211_key_free_unused(struct ie
ieee80211_key_free_common(key);
}
+static bool ieee80211_key_identical(struct ieee80211_sub_if_data *sdata,
+ struct ieee80211_key *old,
+ struct ieee80211_key *new)
+{
+ u8 tkip_old[WLAN_KEY_LEN_TKIP], tkip_new[WLAN_KEY_LEN_TKIP];
+ u8 *tk_old, *tk_new;
+
+ if (!old || new->conf.keylen != old->conf.keylen)
+ return false;
+
+ tk_old = old->conf.key;
+ tk_new = new->conf.key;
+
+ /*
+ * In station mode, don't compare the TX MIC key, as it's never used
+ * and offloaded rekeying may not care to send it to the host. This
+ * is the case in iwlwifi, for example.
+ */
+ if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+ new->conf.cipher == WLAN_CIPHER_SUITE_TKIP &&
+ new->conf.keylen == WLAN_KEY_LEN_TKIP &&
+ !(new->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE)) {
+ memcpy(tkip_old, tk_old, WLAN_KEY_LEN_TKIP);
+ memcpy(tkip_new, tk_new, WLAN_KEY_LEN_TKIP);
+ memset(tkip_old + NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY, 0, 8);
+ memset(tkip_new + NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY, 0, 8);
+ tk_old = tkip_old;
+ tk_new = tkip_new;
+ }
+
+ return !crypto_memneq(tk_old, tk_new, new->conf.keylen);
+}
+
int ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta)
@@ -635,8 +668,7 @@ int ieee80211_key_link(struct ieee80211_
* Silently accept key re-installation without really installing the
* new version of the key to avoid nonce reuse or replay issues.
*/
- if (old_key && key->conf.keylen == old_key->conf.keylen &&
- !crypto_memneq(key->conf.key, old_key->conf.key, key->conf.keylen)) {
+ if (ieee80211_key_identical(sdata, old_key, key)) {
ieee80211_key_free_unused(key);
ret = 0;
goto out;