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linux/net/mac80211/wpa.c
Jouni Malinen a3b8b0569f nl80211: Add Michael MIC failure event 
Define a new nl80211 event, NL80211_CMD_MICHAEL_MIC_FAILURE, to be
used to notify user space about locally detected Michael MIC failures.
This matches with the MLME-MICHAELMICFAILURE.indication() primitive.

Since we do not actually have TSC in the skb anymore when
mac80211_ev_michael_mic_failure() is called, that function is changed
to take in the TSC as an optional parameter instead of as a
requirement to include the TSC after the hdr field (which we did not
really follow). For now, TSC is not included in the events from
mac80211, but it could be added at some point.

Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-04-22 16:54:28 -04:00

612 lines
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/*
* Copyright 2002-2004, Instant802 Networks, Inc.
* Copyright 2008, Jouni Malinen <j@w1.fi>
*
* 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
* published by the Free Software Foundation.
*/
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/compiler.h>
#include <linux/ieee80211.h>
#include <asm/unaligned.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "michael.h"
#include "tkip.h"
#include "aes_ccm.h"
#include "aes_cmac.h"
#include "wpa.h"
ieee80211_tx_result
ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
{
u8 *data, *key, *mic, key_offset;
size_t data_len;
unsigned int hdrlen;
struct ieee80211_hdr *hdr;
struct sk_buff *skb = tx->skb;
int authenticator;
int wpa_test = 0;
int tail;
hdr = (struct ieee80211_hdr *)skb->data;
if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
!ieee80211_is_data_present(hdr->frame_control))
return TX_CONTINUE;
hdrlen = ieee80211_hdrlen(hdr->frame_control);
if (skb->len < hdrlen)
return TX_DROP;
data = skb->data + hdrlen;
data_len = skb->len - hdrlen;
if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
!(tx->flags & IEEE80211_TX_FRAGMENTED) &&
!(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) &&
!wpa_test) {
/* hwaccel - with no need for preallocated room for MMIC */
return TX_CONTINUE;
}
tail = MICHAEL_MIC_LEN;
if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
tail += TKIP_ICV_LEN;
if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < TKIP_IV_LEN))
return TX_DROP;
#if 0
authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
#else
authenticator = 1;
#endif
key_offset = authenticator ?
NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
key = &tx->key->conf.key[key_offset];
mic = skb_put(skb, MICHAEL_MIC_LEN);
michael_mic(key, hdr, data, data_len, mic);
return TX_CONTINUE;
}
ieee80211_rx_result
ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
{
u8 *data, *key = NULL, key_offset;
size_t data_len;
unsigned int hdrlen;
struct ieee80211_hdr *hdr;
u8 mic[MICHAEL_MIC_LEN];
struct sk_buff *skb = rx->skb;
int authenticator = 1, wpa_test = 0;
/* No way to verify the MIC if the hardware stripped it */
if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
return RX_CONTINUE;
hdr = (struct ieee80211_hdr *)skb->data;
if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
!ieee80211_has_protected(hdr->frame_control) ||
!ieee80211_is_data_present(hdr->frame_control))
return RX_CONTINUE;
hdrlen = ieee80211_hdrlen(hdr->frame_control);
if (skb->len < hdrlen + MICHAEL_MIC_LEN)
return RX_DROP_UNUSABLE;
data = skb->data + hdrlen;
data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
#if 0
authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
#else
authenticator = 1;
#endif
key_offset = authenticator ?
NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
key = &rx->key->conf.key[key_offset];
michael_mic(key, hdr, data, data_len, mic);
if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
if (!(rx->flags & IEEE80211_RX_RA_MATCH))
return RX_DROP_UNUSABLE;
mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
(void *) skb->data, NULL);
return RX_DROP_UNUSABLE;
}
/* remove Michael MIC from payload */
skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
/* update IV in key information to be able to detect replays */
rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
return RX_CONTINUE;
}
static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_key *key = tx->key;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
unsigned int hdrlen;
int len, tail;
u8 *pos;
if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
!(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
/* hwaccel - with no need for preallocated room for IV/ICV */
info->control.hw_key = &tx->key->conf;
return 0;
}
hdrlen = ieee80211_hdrlen(hdr->frame_control);
len = skb->len - hdrlen;
if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
tail = 0;
else
tail = TKIP_ICV_LEN;
if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < TKIP_IV_LEN))
return -1;
pos = skb_push(skb, TKIP_IV_LEN);
memmove(pos, pos + TKIP_IV_LEN, hdrlen);
pos += hdrlen;
/* Increase IV for the frame */
key->u.tkip.tx.iv16++;
if (key->u.tkip.tx.iv16 == 0)
key->u.tkip.tx.iv32++;
if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
/* hwaccel - with preallocated room for IV */
ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
info->control.hw_key = &tx->key->conf;
return 0;
}
/* Add room for ICV */
skb_put(skb, TKIP_ICV_LEN);
hdr = (struct ieee80211_hdr *) skb->data;
ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
key, pos, len, hdr->addr2);
return 0;
}
ieee80211_tx_result
ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
{
struct sk_buff *skb = tx->skb;
ieee80211_tx_set_protected(tx);
do {
if (tkip_encrypt_skb(tx, skb) < 0)
return TX_DROP;
} while ((skb = skb->next));
return TX_CONTINUE;
}
ieee80211_rx_result
ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
int hdrlen, res, hwaccel = 0, wpa_test = 0;
struct ieee80211_key *key = rx->key;
struct sk_buff *skb = rx->skb;
hdrlen = ieee80211_hdrlen(hdr->frame_control);
if (!ieee80211_is_data(hdr->frame_control))
return RX_CONTINUE;
if (!rx->sta || skb->len - hdrlen < 12)
return RX_DROP_UNUSABLE;
if (rx->status->flag & RX_FLAG_DECRYPTED) {
if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
/*
* Hardware took care of all processing, including
* replay protection, and stripped the ICV/IV so
* we cannot do any checks here.
*/
return RX_CONTINUE;
}
/* let TKIP code verify IV, but skip decryption */
hwaccel = 1;
}
res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
key, skb->data + hdrlen,
skb->len - hdrlen, rx->sta->sta.addr,
hdr->addr1, hwaccel, rx->queue,
&rx->tkip_iv32,
&rx->tkip_iv16);
if (res != TKIP_DECRYPT_OK || wpa_test)
return RX_DROP_UNUSABLE;
/* Trim ICV */
skb_trim(skb, skb->len - TKIP_ICV_LEN);
/* Remove IV */
memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
skb_pull(skb, TKIP_IV_LEN);
return RX_CONTINUE;
}
static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
int encrypted)
{
__le16 mask_fc;
int a4_included, mgmt;
u8 qos_tid;
u8 *b_0, *aad;
u16 data_len, len_a;
unsigned int hdrlen;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
b_0 = scratch + 3 * AES_BLOCK_LEN;
aad = scratch + 4 * AES_BLOCK_LEN;
/*
* 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(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);
len_a = hdrlen - 2;
a4_included = ieee80211_has_a4(hdr->frame_control);
if (ieee80211_is_data_qos(hdr->frame_control))
qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
else
qos_tid = 0;
data_len = skb->len - hdrlen - CCMP_HDR_LEN;
if (encrypted)
data_len -= CCMP_MIC_LEN;
/* First block, b_0 */
b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
/* 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) */
put_unaligned_be16(data_len, &b_0[14]);
/* AAD (extra authenticate-only data) / masked 802.11 header
* FC | A1 | A2 | A3 | SC | [A4] | [QC] */
put_unaligned_be16(len_a, &aad[0]);
put_unaligned(mask_fc, (__le16 *)&aad[2]);
memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
/* Mask Seq#, leave Frag# */
aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
aad[23] = 0;
if (a4_included) {
memcpy(&aad[24], hdr->addr4, ETH_ALEN);
aad[30] = qos_tid;
aad[31] = 0;
} else {
memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
aad[24] = qos_tid;
}
}
static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
{
hdr[0] = pn[5];
hdr[1] = pn[4];
hdr[2] = 0;
hdr[3] = 0x20 | (key_id << 6);
hdr[4] = pn[3];
hdr[5] = pn[2];
hdr[6] = pn[1];
hdr[7] = pn[0];
}
static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
{
pn[0] = hdr[7];
pn[1] = hdr[6];
pn[2] = hdr[5];
pn[3] = hdr[4];
pn[4] = hdr[1];
pn[5] = hdr[0];
}
static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_key *key = tx->key;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
int hdrlen, len, tail;
u8 *pos, *pn;
int i;
bool skip_hw;
skip_hw = (tx->key->conf.flags & IEEE80211_KEY_FLAG_SW_MGMT) &&
ieee80211_is_mgmt(hdr->frame_control);
if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
!(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
!skip_hw) {
/* hwaccel - with no need for preallocated room for CCMP
* header or MIC fields */
info->control.hw_key = &tx->key->conf;
return 0;
}
hdrlen = ieee80211_hdrlen(hdr->frame_control);
len = skb->len - hdrlen;
if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
tail = 0;
else
tail = CCMP_MIC_LEN;
if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < CCMP_HDR_LEN))
return -1;
pos = skb_push(skb, CCMP_HDR_LEN);
memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
hdr = (struct ieee80211_hdr *) pos;
pos += hdrlen;
/* PN = PN + 1 */
pn = key->u.ccmp.tx_pn;
for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
pn[i]++;
if (pn[i])
break;
}
ccmp_pn2hdr(pos, pn, key->conf.keyidx);
if ((key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) && !skip_hw) {
/* hwaccel - with preallocated room for CCMP header */
info->control.hw_key = &tx->key->conf;
return 0;
}
pos += CCMP_HDR_LEN;
ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
pos, skb_put(skb, CCMP_MIC_LEN));
return 0;
}
ieee80211_tx_result
ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
{
struct sk_buff *skb = tx->skb;
ieee80211_tx_set_protected(tx);
do {
if (ccmp_encrypt_skb(tx, skb) < 0)
return TX_DROP;
} while ((skb = skb->next));
return TX_CONTINUE;
}
ieee80211_rx_result
ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
int hdrlen;
struct ieee80211_key *key = rx->key;
struct sk_buff *skb = rx->skb;
u8 pn[CCMP_PN_LEN];
int data_len;
hdrlen = ieee80211_hdrlen(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;
if (!rx->sta || data_len < 0)
return RX_DROP_UNUSABLE;
if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
(rx->status->flag & RX_FLAG_IV_STRIPPED))
return RX_CONTINUE;
ccmp_hdr2pn(pn, skb->data + hdrlen);
if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
key->u.ccmp.replays++;
return RX_DROP_UNUSABLE;
}
if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
/* hardware didn't decrypt/verify MIC */
ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
if (ieee80211_aes_ccm_decrypt(
key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
skb->data + hdrlen + CCMP_HDR_LEN, data_len,
skb->data + skb->len - CCMP_MIC_LEN,
skb->data + hdrlen + CCMP_HDR_LEN))
return RX_DROP_UNUSABLE;
}
memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
/* Remove CCMP header and MIC */
skb_trim(skb, skb->len - CCMP_MIC_LEN);
memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
skb_pull(skb, CCMP_HDR_LEN);
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;
}
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