From 765cb46a3fc856245ea68a7c961ac87c77e4ae2d Mon Sep 17 00:00:00 2001 From: Jouni Malinen Date: Thu, 8 Jan 2009 13:32:01 +0200 Subject: mac80211: 802.11w - Add BIP (AES-128-CMAC) Implement Broadcast/Multicast Integrity Protocol for management frame protection. This patch adds the needed definitions for the new information element (MMIE) and implementation for the new "encryption" type (though, BIP is actually not encrypting data, it provides only integrity protection). These routines will be used by a follow-on patch that enables BIP for multicast/broadcast robust management frames. Signed-off-by: Jouni Malinen Acked-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/wpa.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) (limited to 'net/mac80211/wpa.c') diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c index aff46adde3f..53e11e6ff66 100644 --- a/net/mac80211/wpa.c +++ b/net/mac80211/wpa.c @@ -1,5 +1,6 @@ /* * Copyright 2002-2004, Instant802 Networks, Inc. + * Copyright 2008, Jouni Malinen * * 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 @@ -19,6 +20,7 @@ #include "michael.h" #include "tkip.h" #include "aes_ccm.h" +#include "aes_cmac.h" #include "wpa.h" ieee80211_tx_result @@ -491,3 +493,126 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx) return RX_CONTINUE; } + + +static void bip_aad(struct sk_buff *skb, u8 *aad) +{ + /* BIP AAD: FC(masked) || A1 || A2 || A3 */ + + /* FC type/subtype */ + aad[0] = skb->data[0]; + /* Mask FC Retry, PwrMgt, MoreData flags to zero */ + aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6)); + /* A1 || A2 || A3 */ + memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN); +} + + +static inline void bip_ipn_swap(u8 *d, const u8 *s) +{ + *d++ = s[5]; + *d++ = s[4]; + *d++ = s[3]; + *d++ = s[2]; + *d++ = s[1]; + *d = s[0]; +} + + +ieee80211_tx_result +ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx) +{ + struct sk_buff *skb = tx->skb; + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); + struct ieee80211_key *key = tx->key; + struct ieee80211_mmie *mmie; + u8 *pn, aad[20]; + int i; + + if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) { + /* hwaccel */ + info->control.hw_key = &tx->key->conf; + return 0; + } + + if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie))) + return TX_DROP; + + mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie)); + mmie->element_id = WLAN_EID_MMIE; + mmie->length = sizeof(*mmie) - 2; + mmie->key_id = cpu_to_le16(key->conf.keyidx); + + /* PN = PN + 1 */ + pn = key->u.aes_cmac.tx_pn; + + for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) { + pn[i]++; + if (pn[i]) + break; + } + bip_ipn_swap(mmie->sequence_number, pn); + + bip_aad(skb, aad); + + /* + * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64) + */ + ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf, + aad, skb->data + 24, skb->len - 24, mmie->mic); + + return TX_CONTINUE; +} + + +ieee80211_rx_result +ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx) +{ + struct sk_buff *skb = rx->skb; + struct ieee80211_key *key = rx->key; + struct ieee80211_mmie *mmie; + u8 aad[20], mic[8], ipn[6]; + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + + if (!ieee80211_is_mgmt(hdr->frame_control)) + return RX_CONTINUE; + + if ((rx->status->flag & RX_FLAG_DECRYPTED) && + (rx->status->flag & RX_FLAG_IV_STRIPPED)) + return RX_CONTINUE; + + if (skb->len < 24 + sizeof(*mmie)) + return RX_DROP_UNUSABLE; + + mmie = (struct ieee80211_mmie *) + (skb->data + skb->len - sizeof(*mmie)); + if (mmie->element_id != WLAN_EID_MMIE || + mmie->length != sizeof(*mmie) - 2) + return RX_DROP_UNUSABLE; /* Invalid MMIE */ + + bip_ipn_swap(ipn, mmie->sequence_number); + + if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) { + key->u.aes_cmac.replays++; + return RX_DROP_UNUSABLE; + } + + if (!(rx->status->flag & RX_FLAG_DECRYPTED)) { + /* hardware didn't decrypt/verify MIC */ + bip_aad(skb, aad); + ieee80211_aes_cmac(key->u.aes_cmac.tfm, + key->u.aes_cmac.rx_crypto_buf, aad, + skb->data + 24, skb->len - 24, mic); + if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) { + key->u.aes_cmac.icverrors++; + return RX_DROP_UNUSABLE; + } + } + + memcpy(key->u.aes_cmac.rx_pn, ipn, 6); + + /* Remove MMIE */ + skb_trim(skb, skb->len - sizeof(*mmie)); + + return RX_CONTINUE; +} -- cgit v1.2.3-70-g09d2