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mac80211: 802.11w - CCMP for management frames

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Extend CCMP to support encryption and decryption of unicast management
frames.

Signed-off-by: Jouni Malinen <j@w1.fi>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Jouni Malinen 2009-01-08 13:32:00 +02:00 committed by John W. Linville
parent 5394af4d86
commit fb73333676
3 changed files with 64 additions and 7 deletions
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30
include/linux/ieee80211.h
View file

@ -1030,6 +1030,7 @@ enum ieee80211_category {
WLAN_CATEGORY_QOS = 1,
WLAN_CATEGORY_DLS = 2,
WLAN_CATEGORY_BACK = 3,
WLAN_CATEGORY_PUBLIC = 4,
WLAN_CATEGORY_WMM = 17,
};
@ -1185,6 +1186,35 @@ static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
return hdr->addr1;
}
/**
* ieee80211_is_robust_mgmt_frame - check if frame is a robust management frame
* @hdr: the frame (buffer must include at least the first octet of payload)
*/
static inline bool ieee80211_is_robust_mgmt_frame(struct ieee80211_hdr *hdr)
{
if (ieee80211_is_disassoc(hdr->frame_control) ||
ieee80211_is_deauth(hdr->frame_control))
return true;
if (ieee80211_is_action(hdr->frame_control)) {
u8 *category;
/*
* Action frames, excluding Public Action frames, are Robust
* Management Frames. However, if we are looking at a Protected
* frame, skip the check since the data may be encrypted and
* the frame has already been found to be a Robust Management
* Frame (by the other end).
*/
if (ieee80211_has_protected(hdr->frame_control))
return true;
category = ((u8 *) hdr) + 24;
return *category != WLAN_CATEGORY_PUBLIC;
}
return false;
}
/**
* ieee80211_fhss_chan_to_freq - get channel frequency
* @channel: the FHSS channel

23
net/mac80211/tx.c
View file

@ -330,6 +330,22 @@ ieee80211_tx_h_multicast_ps_buf(struct ieee80211_tx_data *tx)
return TX_CONTINUE;
}
static int ieee80211_use_mfp(__le16 fc, struct sta_info *sta,
struct sk_buff *skb)
{
if (!ieee80211_is_mgmt(fc))
return 0;
if (sta == NULL || !test_sta_flags(sta, WLAN_STA_MFP))
return 0;
if (!ieee80211_is_robust_mgmt_frame((struct ieee80211_hdr *)
skb->data))
return 0;
return 1;
}
static ieee80211_tx_result
ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
{
@ -428,10 +444,15 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
if (ieee80211_is_auth(hdr->frame_control))
break;
case ALG_TKIP:
case ALG_CCMP:
if (!ieee80211_is_data_present(hdr->frame_control))
tx->key = NULL;
break;
case ALG_CCMP:
if (!ieee80211_is_data_present(hdr->frame_control) &&
!ieee80211_use_mfp(hdr->frame_control, tx->sta,
tx->skb))
tx->key = NULL;
break;
}
}

18
net/mac80211/wpa.c
View file

@ -266,7 +266,7 @@ static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
int encrypted)
{
__le16 mask_fc;
int a4_included;
int a4_included, mgmt;
u8 qos_tid;
u8 *b_0, *aad;
u16 data_len, len_a;
@ -277,12 +277,15 @@ static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
aad = scratch + 4 * AES_BLOCK_LEN;
/*
* Mask FC: zero subtype b4 b5 b6
* Mask FC: zero subtype b4 b5 b6 (if not mgmt)
* Retry, PwrMgt, MoreData; set Protected
*/
mgmt = ieee80211_is_mgmt(hdr->frame_control);
mask_fc = hdr->frame_control;
mask_fc &= ~cpu_to_le16(0x0070 | IEEE80211_FCTL_RETRY |
mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
if (!mgmt)
mask_fc &= ~cpu_to_le16(0x0070);
mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
hdrlen = ieee80211_hdrlen(hdr->frame_control);
@ -300,8 +303,10 @@ static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
/* First block, b_0 */
b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
/* Nonce: QoS Priority | A2 | PN */
b_0[1] = qos_tid;
/* Nonce: Nonce Flags | A2 | PN
* Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
*/
b_0[1] = qos_tid | (mgmt << 4);
memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
memcpy(&b_0[8], pn, CCMP_PN_LEN);
/* l(m) */
@ -446,7 +451,8 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
hdrlen = ieee80211_hdrlen(hdr->frame_control);
if (!ieee80211_is_data(hdr->frame_control))
if (!ieee80211_is_data(hdr->frame_control) &&
!ieee80211_is_robust_mgmt_frame(hdr))
return RX_CONTINUE;
data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;