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mac80211: accept key reinstall without changing anything (CVE-2017-13080)

This commit is contained in:
Salvatore Bonaccorso 2017-11-16 15:17:25 +01:00
parent a2708107ce
commit 5d9e74ced8
3 changed files with 84 additions and 0 deletions
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1
debian/changelog vendored
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@ -85,6 +85,7 @@ linux (4.13.12-1) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* netfilter: nft_set_hash: disable fast_ops for 2-len keys (Closes: #880145)
* mac80211: accept key reinstall without changing anything (CVE-2017-13080)
[ Ben Hutchings ]
* linux-image: Recommend apparmor, as systemd units with an AppArmor

82
debian/patches/bugfix/all/mac80211-accept-key-reinstall-without-changing-anyth.patch vendored Normal file
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@ -0,0 +1,82 @@
From: Johannes Berg <johannes.berg@intel.com>
Date: Tue, 5 Sep 2017 14:54:54 +0200
Subject: mac80211: accept key reinstall without changing anything
Origin: https://git.kernel.org/linus/fdf7cb4185b60c68e1a75e61691c4afdc15dea0e
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-13080
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;
--
2.15.0

1
debian/patches/series vendored
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@ -114,6 +114,7 @@ features/all/lockdown/arm64-add-kernel-config-option-to-lock-down-when.patch
# Security fixes
debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
bugfix/all/mac80211-accept-key-reinstall-without-changing-anyth.patch
# Fix exported symbol versions
bugfix/alpha/alpha-restore-symbol-versions-for-symbols-exported-f.patch