Revision 28f300d23674fa01ae747c66ce861d4ee6aebe8c authored by Pavel Emelyanov on 19 September 2007, 05:46:45 UTC, committed by Linus Torvalds on 19 September 2007, 18:24:18 UTC
It turned out, that the user namespace is released during the do_exit() in
exit_task_namespaces(), but the struct user_struct is released only during the
put_task_struct(), i.e.  MUCH later.

On debug kernels with poisoned slabs this will cause the oops in
uid_hash_remove() because the head of the chain, which resides inside the
struct user_namespace, will be already freed and poisoned.

Since the uid hash itself is required only when someone can search it, i.e.
when the namespace is alive, we can safely unhash all the user_struct-s from
it during the namespace exiting.  The subsequent free_uid() will complete the
user_struct destruction.

For example simple program

   #include <sched.h>

   char stack[2 * 1024 * 1024];

   int f(void *foo)
   {
   	return 0;
   }

   int main(void)
   {
   	clone(f, stack + 1 * 1024 * 1024, 0x10000000, 0);
   	return 0;
   }

run on kernel with CONFIG_USER_NS turned on will oops the
kernel immediately.

This was spotted during OpenVZ kernel testing.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Acked-by: "Serge E. Hallyn" <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 735de22
Raw File
wpa.c
/*
 * 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;
}

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