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