SmartAudio/lichee/linux-4.9/drivers/net/wireless/xr829/umac/wpa.c

/*
 * 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/skbuff.h>
#include <linux/compiler.h>
#include <linux/ieee80211.h>
#include <linux/gfp.h>
#include <asm/unaligned.h>
#include <net/mac80211.h>
#include <crypto/aes.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
mac80211_tx_h_xrmac_michael_mic_add(struct ieee80211_tx_data *tx)
{
	u8 *data, *key, *mic;
	size_t data_len;
	unsigned int hdrlen;
	struct ieee80211_hdr *hdr;
	struct sk_buff *skb = tx->skb;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	int tail;

	hdr = (struct ieee80211_hdr *)skb->data;
	if (!tx->key || tx->key->conf.cipher != WLAN_CIPHER_SUITE_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 (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) {
		/* Need to use software crypto for the test */
		info->control.hw_key = NULL;
	}

	if (info->control.hw_key &&
	    (info->flags & IEEE80211_TX_CTL_DONTFRAG ||
	     tx->local->ops->set_frag_threshold) &&
	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
		/* hwaccel - with no need for SW-generated MMIC */
		return TX_CONTINUE;
	}

	tail = MICHAEL_MIC_LEN;
	if (!info->control.hw_key)
		tail += TKIP_ICV_LEN;

	if (WARN_ON(skb_tailroom(skb) < tail ||
		    skb_headroom(skb) < TKIP_IV_LEN))
		return TX_DROP;

	key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
	mic = skb_put(skb, MICHAEL_MIC_LEN);
	xrmac_michael_mic(key, hdr, data, data_len, mic);
	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
		mic[0]++;

	return TX_CONTINUE;
}


ieee80211_rx_result
ieee80211_rx_h_xrmac_michael_mic_verify(struct ieee80211_rx_data *rx)
{
	u8 *data, *key = NULL;
	size_t data_len;
	unsigned int hdrlen;
	u8 mic[MICHAEL_MIC_LEN];
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

	/*
	 * it makes no sense to check for MIC errors on anything other
	 * than data frames.
	 */
	if (!ieee80211_is_data_present(hdr->frame_control))
		return RX_CONTINUE;

	/*
	 * No way to verify the MIC if the hardware stripped it or
	 * the IV with the key index. In this case we have solely rely
	 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a
	 * MIC failure report.
	 */
	if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) {
		if (status->flag & RX_FLAG_MMIC_ERROR)
			goto mic_fail;

		if (!(status->flag & RX_FLAG_IV_STRIPPED) && rx->key)
			goto update_iv;

		return RX_CONTINUE;
	}

	/*
	 * Some hardware seems to generate Michael MIC failure reports; even
	 * though, the frame was not encrypted with TKIP and therefore has no
	 * MIC. Ignore the flag them to avoid triggering countermeasures.
	 */
	if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
	    !(status->flag & RX_FLAG_DECRYPTED))
		return RX_CONTINUE;

	if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) {
		/*
		 * APs with pairwise keys should never receive Michael MIC
		 * errors for non-zero keyidx because these are reserved for
		 * group keys and only the AP is sending real multicast
		 * frames in the BSS. (
		 */
		return RX_DROP_UNUSABLE;
	}

	if (status->flag & RX_FLAG_MMIC_ERROR)
		goto mic_fail;

	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;
	key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
	xrmac_michael_mic(key, hdr, data, data_len, mic);
	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
		goto mic_fail;

	/* remove Michael MIC from payload */
	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);

update_iv:
	/* update IV in key information to be able to detect replays */
	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;

	return RX_CONTINUE;

mic_fail:
	/*
	 * In some cases the key can be unset - e.g. a multicast packet, in
	 * a driver that supports HW encryption. Send up the key idx only if
	 * the key is set.
	 */
	xrmac_ev_michael_mic_failure(rx->sdata,
					rx->key ? rx->key->conf.keyidx : -1,
					(void *) skb->data, NULL, GFP_ATOMIC);
	return RX_DROP_UNUSABLE;
}


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 long flags;
	unsigned int hdrlen;
	int len, tail;
	u8 *pos;

	if (info->control.hw_key &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
		/* hwaccel - with no need for software-generated IV */
		return 0;
	}

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	len = skb->len - hdrlen;

	if (info->control.hw_key)
		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 */
	spin_lock_irqsave(&key->u.tkip.txlock, flags);
	key->u.tkip.tx.iv16++;
	if (key->u.tkip.tx.iv16 == 0)
		key->u.tkip.tx.iv32++;
	pos = mac80211_tkip_add_iv(pos, key);
	spin_unlock_irqrestore(&key->u.tkip.txlock, flags);

	/* hwaccel - with software IV */
	if (info->control.hw_key)
		return 0;

	/* Add room for ICV */
	skb_put(skb, TKIP_ICV_LEN);

	return mac80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
					   key, skb, pos, len);
}


ieee80211_tx_result
mac80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb = tx->skb;

	mac80211_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
mac80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
	int hdrlen, res, hwaccel = 0;
	struct ieee80211_key *key = rx->key;
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(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;

	/*
	 * Let TKIP code verify IV, but skip decryption.
	 * In the case where hardware checks the IV as well,
	 * we don't even get here, see ieee80211_rx_h_decrypt()
	 */
	if (status->flag & RX_FLAG_DECRYPTED)
		hwaccel = 1;

	res = mac80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
					  key, skb->data + hdrlen,
					  skb->len - hdrlen, rx->sta->sta.addr,
					  hdr->addr1, hwaccel, rx->security_idx,
					  &rx->tkip_iv32,
					  &rx->tkip_iv16);
	if (res != TKIP_DECRYPT_OK)
		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;

	memset(scratch, 0, 6 * AES_BLOCK_SIZE);

	b_0 = scratch + 3 * AES_BLOCK_SIZE;
	aad = scratch + 4 * AES_BLOCK_SIZE;

	/*
	 * 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;
	u8 pn[6];
	u64 pn64;
	u8 scratch[6 * AES_BLOCK_SIZE];

	if (info->control.hw_key &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
		/*
		 * hwaccel has no need for preallocated room for CCMP
		 * header or MIC fields
		 */
		return 0;
	}

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	len = skb->len - hdrlen;

	if (info->control.hw_key)
		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;

	pn64 = atomic64_inc_return(&key->u.ccmp.tx_pn);

	pn[5] = pn64;
	pn[4] = pn64 >> 8;
	pn[3] = pn64 >> 16;
	pn[2] = pn64 >> 24;
	pn[1] = pn64 >> 32;
	pn[0] = pn64 >> 40;

	ccmp_pn2hdr(pos, pn, key->conf.keyidx);

	/* hwaccel - with software CCMP header */
	if (info->control.hw_key)
		return 0;

	pos += CCMP_HDR_LEN;
	ccmp_special_blocks(skb, pn, scratch, 0);
	mac80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
				  pos, skb_put(skb, CCMP_MIC_LEN));

	return 0;
}


ieee80211_tx_result
mac80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb = tx->skb;

	mac80211_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
mac80211_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;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	u8 pn[CCMP_PN_LEN];
	int data_len;
	int queue;
	static const u8 zero_pn[6] = {0};

	hdrlen = ieee80211_hdrlen(hdr->frame_control);

	if (!ieee80211_is_data(hdr->frame_control) &&
	    !ieee80211_is_robust_mgmt_frame(skb))
		return RX_CONTINUE;

	data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
	if (!rx->sta || data_len < 0)
		return RX_DROP_UNUSABLE;

	ccmp_hdr2pn(pn, skb->data + hdrlen);

	queue = rx->security_idx;

    /*Fix bug for first encrypt packet drop after 8021x, the bug makes dhcp process slow.*/
	if ((memcmp(key->u.ccmp.rx_pn[queue], zero_pn, CCMP_PN_LEN) == 0) &&
		(memcmp(pn, zero_pn, CCMP_PN_LEN) == 0)) {
		/*do nothing*/
    } else if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) {
		key->u.ccmp.replays++;
		return RX_DROP_UNUSABLE;
	}

	if (!(status->flag & RX_FLAG_DECRYPTED)) {
		u8 scratch[6 * AES_BLOCK_SIZE];
		/* hardware didn't decrypt/verify MIC */
		ccmp_special_blocks(skb, pn, scratch, 1);

		if (mac80211_aes_ccm_decrypt(
			    key->u.ccmp.tfm, scratch,
			    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;
	}

	/* As long as u.ccmp.rx_pn and u.ccmp.prev_rx_pn are equal, no
	race condition induced.
	It is seen that with Cisco AP and with PTK re-negotiation feature
	enabled on Cisco to do key-negotiaton periodically, even after the
	RX PN is reset by the supplicant, at MAC, we still keep getting
	previous RX PN packets.
	This is due to race condition when this feature is enabled with
	throughput test and is introduced because of the combination of
	different TIDs used for data and EAPOL packets and aggregation.
	The RX PN gets reset to lower value after a while and at that time
	the RX PN value becomes lower then the maintained current PN at MAC.
	As a result, the replay detection code chips in and starts dropping all
	packets till the PN re-match. This causes throughput to stall
	intermittently for the duration till RX PN match with current PN.
	So to take care of this we maintain u.ccmp.prev_rx_pn, which doesn't get
	reset when new PTK is plumbed by supplicant and use it for detecting
	this transition i.e. from higher PN to lower PN and once this situation
	happens start updating u.ccmp.rx_pn and thereafter u.ccmp.rx_pn and
	u.ccmp.prev_rx_pn should be same. In normal scenario, i.e. no new key
	plumbed both counters should be same. */
	if ((memcmp(key->u.ccmp.prev_rx_pn[queue],
		key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) == 0) ||
		(memcmp(key->u.ccmp.prev_rx_pn[queue], pn, CCMP_PN_LEN) > 0)) {
		memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);
		memcpy(key->u.ccmp.prev_rx_pn[queue], pn, CCMP_PN_LEN);
	}

	/* If u.ccmp.rx_pn gets reset to zero due to PTK re-negotiaton then
	don't update it and just keep updating the u.ccmp.prev_rx_pn.
	This is to detect the transition that will happen later i.e. from higher
	RX PN to lower RX PN in case of race condition scenario. */
	if (memcmp(key->u.ccmp.rx_pn[queue], zero_pn, CCMP_PN_LEN) == 0)
		memcpy(key->u.ccmp.prev_rx_pn[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_set64(u8 *d, u64 pn)
{
	*d++ = pn;
	*d++ = pn >> 8;
	*d++ = pn >> 16;
	*d++ = pn >> 24;
	*d++ = pn >> 32;
	*d = pn >> 40;
}

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
mac80211_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 aad[20];
	u64 pn64;

	if (info->control.hw_key)
		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 */
	pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);

	bip_ipn_set64(mmie->sequence_number, pn64);

	bip_aad(skb, aad);

	/*
	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
	 */
	mac80211_aes_cmac(key->u.aes_cmac.tfm, aad,
			   skb->data + 24, skb->len - 24, mmie->mic);

	return TX_CONTINUE;
}


ieee80211_rx_result
mac80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
{
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(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 (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 (!(status->flag & RX_FLAG_DECRYPTED)) {
		/* hardware didn't decrypt/verify MIC */
		bip_aad(skb, aad);
		mac80211_aes_cmac(key->u.aes_cmac.tfm, 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;
}