From 3599fa6eb4415945063710c7be20c74ce6f2e3b4 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Tue, 24 Oct 2017 21:12:13 +0200 Subject: [PATCH] mac80211: don't compare TKIP TX MIC key in reinstall prevention commit cfbb0d90a7abb289edc91833d0905931f8805f12 upstream. 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 [bwh: Backported to 3.2: - Keep using memcmp() as we don't have crypto_memneq() - Adjust context] Signed-off-by: Ben Hutchings --- net/mac80211/key.c | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/net/mac80211/key.c b/net/mac80211/key.c index f2bdd6fc3e76..01c64f408cce 100644 --- a/net/mac80211/key.c +++ b/net/mac80211/key.c @@ -444,6 +444,39 @@ static void __ieee80211_key_destroy(struct ieee80211_key *key) kfree(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 !memcmp(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) @@ -497,8 +530,7 @@ int ieee80211_key_link(struct ieee80211_key *key, * 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)) { + if (ieee80211_key_identical(sdata, old_key, key)) { __ieee80211_key_free(key); ret = 0; goto out; -- 2.39.2