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- From fdf7cb4185b60c68e1a75e61691c4afdc15dea0e Mon Sep 17 00:00:00 2001
- From: Johannes Berg <johannes.berg@intel.com>
- Date: Tue, 5 Sep 2017 14:54:54 +0200
- Subject: [PATCH] mac80211: accept key reinstall without changing anything
- When a key is reinstalled we can reset the replay counters
- etc. which can lead to nonce reuse and/or replay detection
- being impossible, breaking security properties, as described
- in the "KRACK attacks".
- In particular, CVE-2017-13080 applies to GTK rekeying that
- happened in firmware while the host is in D3, with the second
- part of the attack being done after the host wakes up. In
- this case, the wpa_supplicant mitigation isn't sufficient
- since wpa_supplicant doesn't know the GTK material.
- In case this happens, simply silently accept the new key
- coming from userspace but don't take any action on it since
- it's the same key; this keeps the PN replay counters intact.
- Signed-off-by: Johannes Berg <johannes.berg@intel.com>
- ---
- net/mac80211/key.c | 21 +++++++++++++++++----
- 1 file changed, 17 insertions(+), 4 deletions(-)
- diff --git a/net/mac80211/key.c b/net/mac80211/key.c
- index a98fc2b5e0dc..ae995c8480db 100644
- --- a/net/mac80211/key.c
- +++ b/net/mac80211/key.c
- @@ -4,7 +4,7 @@
- * Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
- * Copyright 2007-2008 Johannes Berg <johannes@sipsolutions.net>
- * Copyright 2013-2014 Intel Mobile Communications GmbH
- - * Copyright 2015 Intel Deutschland GmbH
- + * Copyright 2015-2017 Intel Deutschland GmbH
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- @@ -620,9 +620,6 @@ int ieee80211_key_link(struct ieee80211_key *key,
-
- pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
- idx = key->conf.keyidx;
- - key->local = sdata->local;
- - key->sdata = sdata;
- - key->sta = sta;
-
- mutex_lock(&sdata->local->key_mtx);
-
- @@ -633,6 +630,21 @@ int ieee80211_key_link(struct ieee80211_key *key,
- else
- old_key = key_mtx_dereference(sdata->local, sdata->keys[idx]);
-
- + /*
- + * 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 &&
- + !memcmp(key->conf.key, old_key->conf.key, key->conf.keylen)) {
- + ieee80211_key_free_unused(key);
- + ret = 0;
- + goto out;
- + }
- +
- + key->local = sdata->local;
- + key->sdata = sdata;
- + key->sta = sta;
- +
- increment_tailroom_need_count(sdata);
-
- ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
- @@ -648,6 +660,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
- ret = 0;
- }
-
- + out:
- mutex_unlock(&sdata->local->key_mtx);
-
- return ret;
- --
- 2.13.6
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