4.4-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Berg johannes.berg@intel.com
commit fdf7cb4185b60c68e1a75e61691c4afdc15dea0e upstream.
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 Cc: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/mac80211/key.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
--- a/net/mac80211/key.c +++ b/net/mac80211/key.c @@ -4,6 +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 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 @@ -617,9 +618,6 @@ int ieee80211_key_link(struct ieee80211_
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);
@@ -630,6 +628,21 @@ int ieee80211_key_link(struct ieee80211_ 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); @@ -645,6 +658,7 @@ int ieee80211_key_link(struct ieee80211_ ret = 0; }
+ out: mutex_unlock(&sdata->local->key_mtx);
return ret;