text: /*
   * 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
  ieee80211_tx_h_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);
  	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_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];
  	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.
  	 */
  	mac80211_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 = ieee80211_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 ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
  					   key, skb, pos, len);
  }
  
  
  ieee80211_tx_result
  ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
  {
  	struct sk_buff *skb;
  
  	ieee80211_tx_set_protected(tx);
  
  	skb_queue_walk(&tx->skbs, skb) {
  		if (tkip_encrypt_skb(tx, skb) < 0)
  			return TX_DROP;
  	}
  
  	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;
  	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 = ieee80211_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) &&
  	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
  		/*
  		 * 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);
  
  	/* the HW only needs room for the IV, but not the actual IV */
  	if (info->control.hw_key &&
  	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
  		return 0;
  
  	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);
  	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, 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;
  
  	ieee80211_tx_set_protected(tx);
  
  	skb_queue_walk(&tx->skbs, skb) {
  		if (ccmp_encrypt_skb(tx, skb) < 0)
  			return TX_DROP;
  	}
  
  	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;
  	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
  	u8 pn[CCMP_PN_LEN];
  	int data_len;
  	int queue;
  
  	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;
  
  	ccmp_hdr2pn(pn, skb->data + hdrlen);
  
  	queue = rx->security_idx;
  
  	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 (ieee80211_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;
  	}
  
  	memcpy(key->u.ccmp.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
  ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
  {
  	struct sk_buff *skb;
  	struct ieee80211_tx_info *info;
  	struct ieee80211_key *key = tx->key;
  	struct ieee80211_mmie *mmie;
  	u8 aad[20];
  	u64 pn64;
  
  	if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
  		return TX_DROP;
  
  	skb = skb_peek(&tx->skbs);
  
  	info = IEEE80211_SKB_CB(skb);
  
  	if (info->control.hw_key)
  		return TX_CONTINUE;
  
  	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)
  	 */
  	ieee80211_aes_cmac(key->u.aes_cmac.tfm, 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_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);
  		ieee80211_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;
  }
  
  ieee80211_tx_result
  ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
  {
  	struct sk_buff *skb;
  	struct ieee80211_tx_info *info = NULL;
  
  	skb_queue_walk(&tx->skbs, skb) {
  		info  = IEEE80211_SKB_CB(skb);
  
  		/* handle hw-only algorithm */
  		if (!info->control.hw_key)
  			return TX_DROP;
  	}
  
  	ieee80211_tx_set_protected(tx);
  
  	return TX_CONTINUE;
  }
  