[MAC80211]: Add mac80211 wireless stack.

Add mac80211, the IEEE 802.11 software MAC layer.

Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 660 insertions, 0 deletions

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
new file mode 100644
index 00000000000..783af32c691
--- /dev/null
+++ b/net/mac80211/wpa.c
@@ -0,0 +1,660 @@
+/*
+ * Copyright 2002-2004, Instant802 Networks, Inc.
+ *
+ * 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 <net/iw_handler.h>
+
+#include <net/mac80211.h>
+#include "ieee80211_common.h"
+#include "ieee80211_i.h"
+#include "michael.h"
+#include "tkip.h"
+#include "aes_ccm.h"
+#include "wpa.h"
+
+static int ieee80211_get_hdr_info(const struct sk_buff *skb, u8 **sa, u8 **da,
+				  u8 *qos_tid, u8 **data, size_t *data_len)
+{
+	struct ieee80211_hdr *hdr;
+	size_t hdrlen;
+	u16 fc;
+	int a4_included;
+	u8 *pos;
+
+	hdr = (struct ieee80211_hdr *) skb->data;
+	fc = le16_to_cpu(hdr->frame_control);
+
+	hdrlen = 24;
+	if ((fc & (IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS)) ==
+	    (IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS)) {
+		hdrlen += ETH_ALEN;
+		*sa = hdr->addr4;
+		*da = hdr->addr3;
+	} else if (fc & IEEE80211_FCTL_FROMDS) {
+		*sa = hdr->addr3;
+		*da = hdr->addr1;
+	} else if (fc & IEEE80211_FCTL_TODS) {
+		*sa = hdr->addr2;
+		*da = hdr->addr3;
+	} else {
+		*sa = hdr->addr2;
+		*da = hdr->addr1;
+	}
+
+	if (fc & 0x80)
+		hdrlen += 2;
+
+	*data = skb->data + hdrlen;
+	*data_len = skb->len - hdrlen;
+
+	a4_included = (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
+		(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS);
+	if ((fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
+	    fc & IEEE80211_STYPE_QOS_DATA) {
+		pos = (u8 *) &hdr->addr4;
+		if (a4_included)
+			pos += 6;
+		*qos_tid = pos[0] & 0x0f;
+		*qos_tid |= 0x80; /* qos_included flag */
+	} else
+		*qos_tid = 0;
+
+	return skb->len < hdrlen ? -1 : 0;
+}
+
+
+ieee80211_txrx_result
+ieee80211_tx_h_michael_mic_add(struct ieee80211_txrx_data *tx)
+{
+	u8 *data, *sa, *da, *key, *mic, qos_tid;
+	size_t data_len;
+	u16 fc;
+	struct sk_buff *skb = tx->skb;
+	int authenticator;
+	int wpa_test = 0;
+
+	fc = tx->fc;
+
+	if (!tx->key || tx->key->alg != ALG_TKIP || skb->len < 24 ||
+	    !WLAN_FC_DATA_PRESENT(fc))
+		return TXRX_CONTINUE;
+
+	if (ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len))
+		return TXRX_DROP;
+
+	if (!tx->key->force_sw_encrypt &&
+	    !tx->fragmented &&
+	    !(tx->local->hw.flags & IEEE80211_HW_TKIP_INCLUDE_MMIC) &&
+	    !wpa_test) {
+		/* hwaccel - with no need for preallocated room for Michael MIC
+		 */
+		return TXRX_CONTINUE;
+	}
+
+	if (skb_tailroom(skb) < MICHAEL_MIC_LEN) {
+		I802_DEBUG_INC(tx->local->tx_expand_skb_head);
+		if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN,
+					      MICHAEL_MIC_LEN + TKIP_ICV_LEN,
+					      GFP_ATOMIC))) {
+			printk(KERN_DEBUG "%s: failed to allocate more memory "
+			       "for Michael MIC\n", tx->dev->name);
+			return TXRX_DROP;
+		}
+	}
+
+#if 0
+	authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
+#else
+	authenticator = 1;
+#endif
+	key = &tx->key->key[authenticator ? ALG_TKIP_TEMP_AUTH_TX_MIC_KEY :
+			    ALG_TKIP_TEMP_AUTH_RX_MIC_KEY];
+	mic = skb_put(skb, MICHAEL_MIC_LEN);
+	michael_mic(key, da, sa, qos_tid & 0x0f, data, data_len, mic);
+
+	return TXRX_CONTINUE;
+}
+
+
+ieee80211_txrx_result
+ieee80211_rx_h_michael_mic_verify(struct ieee80211_txrx_data *rx)
+{
+	u8 *data, *sa, *da, *key = NULL, qos_tid;
+	size_t data_len;
+	u16 fc;
+	u8 mic[MICHAEL_MIC_LEN];
+	struct sk_buff *skb = rx->skb;
+	int authenticator = 1, wpa_test = 0;
+
+	fc = rx->fc;
+
+	/* If device handles decryption totally, skip this check */
+	if ((rx->local->hw.flags & IEEE80211_HW_DEVICE_HIDES_WEP) ||
+	    (rx->local->hw.flags & IEEE80211_HW_DEVICE_STRIPS_MIC))
+		return TXRX_CONTINUE;
+
+	if (!rx->key || rx->key->alg != ALG_TKIP ||
+	    !(rx->fc & IEEE80211_FCTL_PROTECTED) || !WLAN_FC_DATA_PRESENT(fc))
+		return TXRX_CONTINUE;
+
+	if ((rx->u.rx.status->flag & RX_FLAG_DECRYPTED) &&
+	    !rx->key->force_sw_encrypt) {
+		if (rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV) {
+			if (skb->len < MICHAEL_MIC_LEN)
+				return TXRX_DROP;
+		}
+		/* Need to verify Michael MIC sometimes in software even when
+		 * hwaccel is used. Atheros ar5212: fragmented frames and QoS
+		 * frames. */
+		if (!rx->fragmented && !wpa_test)
+			goto remove_mic;
+	}
+
+	if (ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len)
+	    || data_len < MICHAEL_MIC_LEN)
+		return TXRX_DROP;
+
+	data_len -= MICHAEL_MIC_LEN;
+
+#if 0
+	authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
+#else
+	authenticator = 1;
+#endif
+	key = &rx->key->key[authenticator ? ALG_TKIP_TEMP_AUTH_RX_MIC_KEY :
+			    ALG_TKIP_TEMP_AUTH_TX_MIC_KEY];
+	michael_mic(key, da, sa, qos_tid & 0x0f, data, data_len, mic);
+	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
+		if (!rx->u.rx.ra_match)
+			return TXRX_DROP;
+
+		printk(KERN_DEBUG "%s: invalid Michael MIC in data frame from "
+		       MAC_FMT "\n", rx->dev->name, MAC_ARG(sa));
+
+		do {
+			struct ieee80211_hdr *hdr;
+			union iwreq_data wrqu;
+			char *buf = kmalloc(128, GFP_ATOMIC);
+			if (!buf)
+				break;
+
+			/* TODO: needed parameters: count, key type, TSC */
+			hdr = (struct ieee80211_hdr *) skb->data;
+			sprintf(buf, "MLME-MICHAELMICFAILURE.indication("
+				"keyid=%d %scast addr=" MAC_FMT ")",
+				rx->key->keyidx,
+				hdr->addr1[0] & 0x01 ? "broad" : "uni",
+				MAC_ARG(hdr->addr2));
+			memset(&wrqu, 0, sizeof(wrqu));
+			wrqu.data.length = strlen(buf);
+			wireless_send_event(rx->dev, IWEVCUSTOM, &wrqu, buf);
+			kfree(buf);
+		} while (0);
+
+		if (!rx->local->apdev)
+			return TXRX_DROP;
+
+		ieee80211_rx_mgmt(rx->local, rx->skb, rx->u.rx.status,
+				  ieee80211_msg_michael_mic_failure);
+
+		return TXRX_QUEUED;
+	}
+
+ remove_mic:
+	/* remove Michael MIC from payload */
+	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
+
+	return TXRX_CONTINUE;
+}
+
+
+static int tkip_encrypt_skb(struct ieee80211_txrx_data *tx,
+			    struct sk_buff *skb, int test)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct ieee80211_key *key = tx->key;
+	int hdrlen, len, tailneed;
+	u16 fc;
+	u8 *pos;
+
+	fc = le16_to_cpu(hdr->frame_control);
+	hdrlen = ieee80211_get_hdrlen(fc);
+	len = skb->len - hdrlen;
+
+	tailneed = !tx->key->force_sw_encrypt ? 0 : TKIP_ICV_LEN;
+	if ((skb_headroom(skb) < TKIP_IV_LEN ||
+	     skb_tailroom(skb) < tailneed)) {
+		I802_DEBUG_INC(tx->local->tx_expand_skb_head);
+		if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN, tailneed,
+					      GFP_ATOMIC)))
+			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.iv16++;
+	if (key->u.tkip.iv16 == 0)
+		key->u.tkip.iv32++;
+
+	if (!tx->key->force_sw_encrypt) {
+		u32 flags = tx->local->hw.flags;
+		hdr = (struct ieee80211_hdr *)skb->data;
+
+		/* hwaccel - with preallocated room for IV */
+		ieee80211_tkip_add_iv(pos, key,
+				      (u8) (key->u.tkip.iv16 >> 8),
+				      (u8) (((key->u.tkip.iv16 >> 8) | 0x20) &
+					    0x7f),
+				      (u8) key->u.tkip.iv16);
+
+		if (flags & IEEE80211_HW_TKIP_REQ_PHASE2_KEY)
+			ieee80211_tkip_gen_rc4key(key, hdr->addr2,
+						  tx->u.tx.control->tkip_key);
+		else if (flags & IEEE80211_HW_TKIP_REQ_PHASE1_KEY) {
+			if (key->u.tkip.iv16 == 0 ||
+			    !key->u.tkip.tx_initialized) {
+				ieee80211_tkip_gen_phase1key(key, hdr->addr2,
+					    (u16 *)tx->u.tx.control->tkip_key);
+				key->u.tkip.tx_initialized = 1;
+				tx->u.tx.control->flags |=
+					    IEEE80211_TXCTL_TKIP_NEW_PHASE1_KEY;
+			} else
+				tx->u.tx.control->flags &=
+					    ~IEEE80211_TXCTL_TKIP_NEW_PHASE1_KEY;
+		}
+
+		tx->u.tx.control->key_idx = tx->key->hw_key_idx;
+		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_txrx_result
+ieee80211_tx_h_tkip_encrypt(struct ieee80211_txrx_data *tx)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) tx->skb->data;
+	u16 fc;
+	struct ieee80211_key *key = tx->key;
+	struct sk_buff *skb = tx->skb;
+	int wpa_test = 0, test = 0;
+
+	fc = le16_to_cpu(hdr->frame_control);
+
+	if (!key || key->alg != ALG_TKIP || !WLAN_FC_DATA_PRESENT(fc))
+		return TXRX_CONTINUE;
+
+	tx->u.tx.control->icv_len = TKIP_ICV_LEN;
+	tx->u.tx.control->iv_len = TKIP_IV_LEN;
+	ieee80211_tx_set_iswep(tx);
+
+	if (!tx->key->force_sw_encrypt &&
+	    !(tx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV) &&
+	    !wpa_test) {
+		/* hwaccel - with no need for preallocated room for IV/ICV */
+		tx->u.tx.control->key_idx = tx->key->hw_key_idx;
+		return TXRX_CONTINUE;
+	}
+
+	if (tkip_encrypt_skb(tx, skb, test) < 0)
+		return TXRX_DROP;
+
+	if (tx->u.tx.extra_frag) {
+		int i;
+		for (i = 0; i < tx->u.tx.num_extra_frag; i++) {
+			if (tkip_encrypt_skb(tx, tx->u.tx.extra_frag[i], test)
+			    < 0)
+				return TXRX_DROP;
+		}
+	}
+
+	return TXRX_CONTINUE;
+}
+
+
+ieee80211_txrx_result
+ieee80211_rx_h_tkip_decrypt(struct ieee80211_txrx_data *rx)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
+	u16 fc;
+	int hdrlen, res, hwaccel = 0, wpa_test = 0;
+	struct ieee80211_key *key = rx->key;
+	struct sk_buff *skb = rx->skb;
+
+	fc = le16_to_cpu(hdr->frame_control);
+	hdrlen = ieee80211_get_hdrlen(fc);
+
+	if (!rx->key || rx->key->alg != ALG_TKIP ||
+	    !(rx->fc & IEEE80211_FCTL_PROTECTED) ||
+	    (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
+		return TXRX_CONTINUE;
+
+	if (!rx->sta || skb->len - hdrlen < 12)
+		return TXRX_DROP;
+
+	if ((rx->u.rx.status->flag & RX_FLAG_DECRYPTED) &&
+	    !rx->key->force_sw_encrypt) {
+		if (!(rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV)) {
+			/* Hardware takes care of all processing, including
+			 * replay protection, so no need to continue here. */
+			return TXRX_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->addr,
+					  hwaccel, rx->u.rx.queue);
+	if (res != TKIP_DECRYPT_OK || wpa_test) {
+		printk(KERN_DEBUG "%s: TKIP decrypt failed for RX frame from "
+		       MAC_FMT " (res=%d)\n",
+		       rx->dev->name, MAC_ARG(rx->sta->addr), res);
+		return TXRX_DROP;
+	}
+
+	/* 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 TXRX_CONTINUE;
+}
+
+
+static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
+				int encrypted)
+{
+	u16 fc;
+	int a4_included, qos_included;
+	u8 qos_tid, *fc_pos, *data, *sa, *da;
+	int len_a;
+	size_t data_len;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+
+	fc_pos = (u8 *) &hdr->frame_control;
+	fc = fc_pos[0] ^ (fc_pos[1] << 8);
+	a4_included = (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
+		(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS);
+
+	ieee80211_get_hdr_info(skb, &sa, &da, &qos_tid, &data, &data_len);
+	data_len -= CCMP_HDR_LEN + (encrypted ? CCMP_MIC_LEN : 0);
+	if (qos_tid & 0x80) {
+		qos_included = 1;
+		qos_tid &= 0x0f;
+	} else
+		qos_included = 0;
+	/* 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;
+	memcpy(&b_0[2], hdr->addr2, 6);
+	memcpy(&b_0[8], pn, CCMP_PN_LEN);
+	/* l(m) */
+	b_0[14] = (data_len >> 8) & 0xff;
+	b_0[15] = data_len & 0xff;
+
+
+	/* AAD (extra authenticate-only data) / masked 802.11 header
+	 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
+
+	len_a = a4_included ? 28 : 22;
+	if (qos_included)
+		len_a += 2;
+
+	aad[0] = 0; /* (len_a >> 8) & 0xff; */
+	aad[1] = len_a & 0xff;
+	/* Mask FC: zero subtype b4 b5 b6 */
+	aad[2] = fc_pos[0] & ~(BIT(4) | BIT(5) | BIT(6));
+	/* Retry, PwrMgt, MoreData; set Protected */
+	aad[3] = (fc_pos[1] & ~(BIT(3) | BIT(4) | BIT(5))) | BIT(6);
+	memcpy(&aad[4], &hdr->addr1, 18);
+
+	/* Mask Seq#, leave Frag# */
+	aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
+	aad[23] = 0;
+	if (a4_included) {
+		memcpy(&aad[24], hdr->addr4, 6);
+		aad[30] = 0;
+		aad[31] = 0;
+	} else
+		memset(&aad[24], 0, 8);
+	if (qos_included) {
+		u8 *dpos = &aad[a4_included ? 30 : 24];
+
+		/* Mask QoS Control field */
+		dpos[0] = qos_tid;
+		dpos[1] = 0;
+	}
+}
+
+
+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 int 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];
+	return (hdr[3] >> 6) & 0x03;
+}
+
+
+static int ccmp_encrypt_skb(struct ieee80211_txrx_data *tx,
+			    struct sk_buff *skb, int test)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct ieee80211_key *key = tx->key;
+	int hdrlen, len, tailneed;
+	u16 fc;
+	u8 *pos, *pn, *b_0, *aad, *scratch;
+	int i;
+
+	scratch = key->u.ccmp.tx_crypto_buf;
+	b_0 = scratch + 3 * AES_BLOCK_LEN;
+	aad = scratch + 4 * AES_BLOCK_LEN;
+
+	fc = le16_to_cpu(hdr->frame_control);
+	hdrlen = ieee80211_get_hdrlen(fc);
+	len = skb->len - hdrlen;
+
+	tailneed = !key->force_sw_encrypt ? 0 : CCMP_MIC_LEN;
+
+	if ((skb_headroom(skb) < CCMP_HDR_LEN ||
+	     skb_tailroom(skb) < tailneed)) {
+		I802_DEBUG_INC(tx->local->tx_expand_skb_head);
+		if (unlikely(pskb_expand_head(skb, CCMP_HDR_LEN, tailneed,
+					      GFP_ATOMIC)))
+			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->keyidx);
+
+	if (!key->force_sw_encrypt) {
+		/* hwaccel - with preallocated room for CCMP header */
+		tx->u.tx.control->key_idx = key->hw_key_idx;
+		return 0;
+	}
+
+	pos += CCMP_HDR_LEN;
+	ccmp_special_blocks(skb, pn, b_0, aad, 0);
+	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, b_0, aad, pos, len,
+				  pos, skb_put(skb, CCMP_MIC_LEN));
+
+	return 0;
+}
+
+
+ieee80211_txrx_result
+ieee80211_tx_h_ccmp_encrypt(struct ieee80211_txrx_data *tx)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) tx->skb->data;
+	struct ieee80211_key *key = tx->key;
+	u16 fc;
+	struct sk_buff *skb = tx->skb;
+	int test = 0;
+
+	fc = le16_to_cpu(hdr->frame_control);
+
+	if (!key || key->alg != ALG_CCMP || !WLAN_FC_DATA_PRESENT(fc))
+		return TXRX_CONTINUE;
+
+	tx->u.tx.control->icv_len = CCMP_MIC_LEN;
+	tx->u.tx.control->iv_len = CCMP_HDR_LEN;
+	ieee80211_tx_set_iswep(tx);
+
+	if (!tx->key->force_sw_encrypt &&
+	    !(tx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV)) {
+		/* hwaccel - with no need for preallocated room for CCMP "
+		 * header or MIC fields */
+		tx->u.tx.control->key_idx = tx->key->hw_key_idx;
+		return TXRX_CONTINUE;
+	}
+
+	if (ccmp_encrypt_skb(tx, skb, test) < 0)
+		return TXRX_DROP;
+
+	if (tx->u.tx.extra_frag) {
+		int i;
+
+		for (i = 0; i < tx->u.tx.num_extra_frag; i++) {
+			if (ccmp_encrypt_skb(tx, tx->u.tx.extra_frag[i], test)
+			    < 0)
+				return TXRX_DROP;
+		}
+	}
+
+	return TXRX_CONTINUE;
+}
+
+
+ieee80211_txrx_result
+ieee80211_rx_h_ccmp_decrypt(struct ieee80211_txrx_data *rx)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
+	u16 fc;
+	int hdrlen;
+	struct ieee80211_key *key = rx->key;
+	struct sk_buff *skb = rx->skb;
+	u8 pn[CCMP_PN_LEN];
+	int data_len;
+
+	fc = le16_to_cpu(hdr->frame_control);
+	hdrlen = ieee80211_get_hdrlen(fc);
+
+	if (!key || key->alg != ALG_CCMP ||
+	    !(rx->fc & IEEE80211_FCTL_PROTECTED) ||
+	    (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
+		return TXRX_CONTINUE;
+
+	data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
+	if (!rx->sta || data_len < 0)
+		return TXRX_DROP;
+
+	if ((rx->u.rx.status->flag & RX_FLAG_DECRYPTED) &&
+	    !key->force_sw_encrypt &&
+	    !(rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV))
+		return TXRX_CONTINUE;
+
+	(void) ccmp_hdr2pn(pn, skb->data + hdrlen);
+
+	if (memcmp(pn, key->u.ccmp.rx_pn[rx->u.rx.queue], CCMP_PN_LEN) <= 0) {
+#ifdef CONFIG_MAC80211_DEBUG
+		u8 *ppn = key->u.ccmp.rx_pn[rx->u.rx.queue];
+		printk(KERN_DEBUG "%s: CCMP replay detected for RX frame from "
+		       MAC_FMT " (RX PN %02x%02x%02x%02x%02x%02x <= prev. PN "
+		       "%02x%02x%02x%02x%02x%02x)\n", rx->dev->name,
+		       MAC_ARG(rx->sta->addr),
+		       pn[0], pn[1], pn[2], pn[3], pn[4], pn[5],
+		       ppn[0], ppn[1], ppn[2], ppn[3], ppn[4], ppn[5]);
+#endif /* CONFIG_MAC80211_DEBUG */
+		key->u.ccmp.replays++;
+		return TXRX_DROP;
+	}
+
+	if ((rx->u.rx.status->flag & RX_FLAG_DECRYPTED) &&
+	    !key->force_sw_encrypt) {
+		/* hwaccel has already decrypted frame and verified MIC */
+	} else {
+		u8 *scratch, *b_0, *aad;
+
+		scratch = key->u.ccmp.rx_crypto_buf;
+		b_0 = scratch + 3 * AES_BLOCK_LEN;
+		aad = scratch + 4 * AES_BLOCK_LEN;
+
+		ccmp_special_blocks(skb, pn, b_0, aad, 1);
+
+		if (ieee80211_aes_ccm_decrypt(
+			    key->u.ccmp.tfm, scratch, b_0, aad,
+			    skb->data + hdrlen + CCMP_HDR_LEN, data_len,
+			    skb->data + skb->len - CCMP_MIC_LEN,
+			    skb->data + hdrlen + CCMP_HDR_LEN)) {
+			printk(KERN_DEBUG "%s: CCMP decrypt failed for RX "
+			       "frame from " MAC_FMT "\n", rx->dev->name,
+			       MAC_ARG(rx->sta->addr));
+			return TXRX_DROP;
+		}
+	}
+
+	memcpy(key->u.ccmp.rx_pn[rx->u.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 TXRX_CONTINUE;
+}
+