[MAC80211]: fix race conditions with keys

[linux-2.6] / net / mac80211 / rx.c

/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
 *
 * 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/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rcupdate.h>
#include <net/mac80211.h>
#include <net/ieee80211_radiotap.h>

#include "ieee80211_i.h"
#include "ieee80211_led.h"
#include "ieee80211_common.h"
#include "wep.h"
#include "wpa.h"
#include "tkip.h"
#include "wme.h"

/* pre-rx handlers
 *
 * these don't have dev/sdata fields in the rx data
 * The sta value should also not be used because it may
 * be NULL even though a STA (in IBSS mode) will be added.
 */

static ieee80211_txrx_result
ieee80211_rx_h_parse_qos(struct ieee80211_txrx_data *rx)
{
        u8 *data = rx->skb->data;
        int tid;

        /* does the frame have a qos control field? */
        if (WLAN_FC_IS_QOS_DATA(rx->fc)) {
                u8 *qc = data + ieee80211_get_hdrlen(rx->fc) - QOS_CONTROL_LEN;
                /* frame has qos control */
                tid = qc[0] & QOS_CONTROL_TID_MASK;
        } else {
                if (unlikely((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT)) {
                        /* Separate TID for management frames */
                        tid = NUM_RX_DATA_QUEUES - 1;
                } else {
                        /* no qos control present */
                        tid = 0; /* 802.1d - Best Effort */
                }
        }

        I802_DEBUG_INC(rx->local->wme_rx_queue[tid]);
        /* only a debug counter, sta might not be assigned properly yet */
        if (rx->sta)
                I802_DEBUG_INC(rx->sta->wme_rx_queue[tid]);

        rx->u.rx.queue = tid;
        /* Set skb->priority to 1d tag if highest order bit of TID is not set.
         * For now, set skb->priority to 0 for other cases. */
        rx->skb->priority = (tid > 7) ? 0 : tid;

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_load_stats(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct sk_buff *skb = rx->skb;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        u32 load = 0, hdrtime;
        struct ieee80211_rate *rate;
        struct ieee80211_hw_mode *mode = local->hw.conf.mode;
        int i;

        /* Estimate total channel use caused by this frame */

        if (unlikely(mode->num_rates < 0))
                return TXRX_CONTINUE;

        rate = &mode->rates[0];
        for (i = 0; i < mode->num_rates; i++) {
                if (mode->rates[i].val == rx->u.rx.status->rate) {
                        rate = &mode->rates[i];
                        break;
                }
        }

        /* 1 bit at 1 Mbit/s takes 1 usec; in channel_use values,
         * 1 usec = 1/8 * (1080 / 10) = 13.5 */

        if (mode->mode == MODE_IEEE80211A ||
            mode->mode == MODE_ATHEROS_TURBO ||
            mode->mode == MODE_ATHEROS_TURBOG ||
            (mode->mode == MODE_IEEE80211G &&
             rate->flags & IEEE80211_RATE_ERP))
                hdrtime = CHAN_UTIL_HDR_SHORT;
        else
                hdrtime = CHAN_UTIL_HDR_LONG;

        load = hdrtime;
        if (!is_multicast_ether_addr(hdr->addr1))
                load += hdrtime;

        load += skb->len * rate->rate_inv;

        /* Divide channel_use by 8 to avoid wrapping around the counter */
        load >>= CHAN_UTIL_SHIFT;
        local->channel_use_raw += load;
        rx->u.rx.load = load;

        return TXRX_CONTINUE;
}

ieee80211_rx_handler ieee80211_rx_pre_handlers[] =
{
        ieee80211_rx_h_parse_qos,
        ieee80211_rx_h_load_stats,
        NULL
};

/* rx handlers */

static ieee80211_txrx_result
ieee80211_rx_h_if_stats(struct ieee80211_txrx_data *rx)
{
        if (rx->sta)
                rx->sta->channel_use_raw += rx->u.rx.load;
        rx->sdata->channel_use_raw += rx->u.rx.load;
        return TXRX_CONTINUE;
}

static void
ieee80211_rx_monitor(struct net_device *dev, struct sk_buff *skb,
                     struct ieee80211_rx_status *status)
{
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_rate *rate;
        struct ieee80211_rtap_hdr {
                struct ieee80211_radiotap_header hdr;
                u8 flags;
                u8 rate;
                __le16 chan_freq;
                __le16 chan_flags;
                u8 antsignal;
        } __attribute__ ((packed)) *rthdr;

        skb->dev = dev;

        sdata = IEEE80211_DEV_TO_SUB_IF(dev);

        if (status->flag & RX_FLAG_RADIOTAP)
                goto out;

        if (skb_headroom(skb) < sizeof(*rthdr)) {
                I802_DEBUG_INC(local->rx_expand_skb_head);
                if (pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) {
                        dev_kfree_skb(skb);
                        return;
                }
        }

        rthdr = (struct ieee80211_rtap_hdr *) skb_push(skb, sizeof(*rthdr));
        memset(rthdr, 0, sizeof(*rthdr));
        rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr));
        rthdr->hdr.it_present =
                cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                            (1 << IEEE80211_RADIOTAP_RATE) |
                            (1 << IEEE80211_RADIOTAP_CHANNEL) |
                            (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL));
        rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ?
                       IEEE80211_RADIOTAP_F_FCS : 0;
        rate = ieee80211_get_rate(local, status->phymode, status->rate);
        if (rate)
                rthdr->rate = rate->rate / 5;
        rthdr->chan_freq = cpu_to_le16(status->freq);
        rthdr->chan_flags =
                status->phymode == MODE_IEEE80211A ?
                cpu_to_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ) :
                cpu_to_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ);
        rthdr->antsignal = status->ssi;

 out:
        sdata->stats.rx_packets++;
        sdata->stats.rx_bytes += skb->len;

        skb_set_mac_header(skb, 0);
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb->pkt_type = PACKET_OTHERHOST;
        skb->protocol = htons(ETH_P_802_2);
        memset(skb->cb, 0, sizeof(skb->cb));
        netif_rx(skb);
}

static ieee80211_txrx_result
ieee80211_rx_h_monitor(struct ieee80211_txrx_data *rx)
{
        if (rx->sdata->type == IEEE80211_IF_TYPE_MNTR) {
                ieee80211_rx_monitor(rx->dev, rx->skb, rx->u.rx.status);
                return TXRX_QUEUED;
        }

        if (rx->u.rx.status->flag & RX_FLAG_RADIOTAP)
                skb_pull(rx->skb, ieee80211_get_radiotap_len(rx->skb->data));

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_passive_scan(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct sk_buff *skb = rx->skb;

        if (unlikely(local->sta_scanning != 0)) {
                ieee80211_sta_rx_scan(rx->dev, skb, rx->u.rx.status);
                return TXRX_QUEUED;
        }

        if (unlikely(rx->flags & IEEE80211_TXRXD_RXIN_SCAN)) {
                /* scanning finished during invoking of handlers */
                I802_DEBUG_INC(local->rx_handlers_drop_passive_scan);
                return TXRX_DROP;
        }

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_check(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_hdr *hdr;
        hdr = (struct ieee80211_hdr *) rx->skb->data;

        /* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */
        if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) {
                if (unlikely(rx->fc & IEEE80211_FCTL_RETRY &&
                             rx->sta->last_seq_ctrl[rx->u.rx.queue] ==
                             hdr->seq_ctrl)) {
                        if (rx->flags & IEEE80211_TXRXD_RXRA_MATCH) {
                                rx->local->dot11FrameDuplicateCount++;
                                rx->sta->num_duplicates++;
                        }
                        return TXRX_DROP;
                } else
                        rx->sta->last_seq_ctrl[rx->u.rx.queue] = hdr->seq_ctrl;
        }

        if ((rx->local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) &&
            rx->skb->len > FCS_LEN)
                skb_trim(rx->skb, rx->skb->len - FCS_LEN);

        if (unlikely(rx->skb->len < 16)) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_short);
                return TXRX_DROP;
        }

        if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
                rx->skb->pkt_type = PACKET_OTHERHOST;
        else if (compare_ether_addr(rx->dev->dev_addr, hdr->addr1) == 0)
                rx->skb->pkt_type = PACKET_HOST;
        else if (is_multicast_ether_addr(hdr->addr1)) {
                if (is_broadcast_ether_addr(hdr->addr1))
                        rx->skb->pkt_type = PACKET_BROADCAST;
                else
                        rx->skb->pkt_type = PACKET_MULTICAST;
        } else
                rx->skb->pkt_type = PACKET_OTHERHOST;

        /* Drop disallowed frame classes based on STA auth/assoc state;
         * IEEE 802.11, Chap 5.5.
         *
         * 80211.o does filtering only based on association state, i.e., it
         * drops Class 3 frames from not associated stations. hostapd sends
         * deauth/disassoc frames when needed. In addition, hostapd is
         * responsible for filtering on both auth and assoc states.
         */
        if (unlikely(((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA ||
                      ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL &&
                       (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)) &&
                     rx->sdata->type != IEEE80211_IF_TYPE_IBSS &&
                     (!rx->sta || !(rx->sta->flags & WLAN_STA_ASSOC)))) {
                if ((!(rx->fc & IEEE80211_FCTL_FROMDS) &&
                     !(rx->fc & IEEE80211_FCTL_TODS) &&
                     (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA)
                    || !(rx->flags & IEEE80211_TXRXD_RXRA_MATCH)) {
                        /* Drop IBSS frames and frames for other hosts
                         * silently. */
                        return TXRX_DROP;
                }

                if (!rx->local->apdev)
                        return TXRX_DROP;

                ieee80211_rx_mgmt(rx->local, rx->skb, rx->u.rx.status,
                                  ieee80211_msg_sta_not_assoc);
                return TXRX_QUEUED;
        }

        return TXRX_CONTINUE;
}


static ieee80211_txrx_result
ieee80211_rx_h_load_key(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
        int keyidx;
        int hdrlen;
        struct ieee80211_key *stakey = NULL;

        /*
         * Key selection 101
         *
         * There are three types of keys:
         *  - GTK (group keys)
         *  - PTK (pairwise keys)
         *  - STK (station-to-station pairwise keys)
         *
         * When selecting a key, we have to distinguish between multicast
         * (including broadcast) and unicast frames, the latter can only
         * use PTKs and STKs while the former always use GTKs. Unless, of
         * course, actual WEP keys ("pre-RSNA") are used, then unicast
         * frames can also use key indizes like GTKs. Hence, if we don't
         * have a PTK/STK we check the key index for a WEP key.
         *
         * Note that in a regular BSS, multicast frames are sent by the
         * AP only, associated stations unicast the frame to the AP first
         * which then multicasts it on their behalf.
         *
         * There is also a slight problem in IBSS mode: GTKs are negotiated
         * with each station, that is something we don't currently handle.
         * The spec seems to expect that one negotiates the same key with
         * every station but there's no such requirement; VLANs could be
         * possible.
         */

        if (!(rx->fc & IEEE80211_FCTL_PROTECTED))
                return TXRX_CONTINUE;

        /*
         * No point in finding a key if the frame is neither
         * addressed to us nor a multicast frame.
         */
        if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
                return TXRX_CONTINUE;

        if (rx->sta)
                stakey = rcu_dereference(rx->sta->key);

        if (!is_multicast_ether_addr(hdr->addr1) && stakey) {
                rx->key = stakey;
        } else {
                /*
                 * The device doesn't give us the IV so we won't be
                 * able to look up the key. That's ok though, we
                 * don't need to decrypt the frame, we just won't
                 * be able to keep statistics accurate.
                 * Except for key threshold notifications, should
                 * we somehow allow the driver to tell us which key
                 * the hardware used if this flag is set?
                 */
                if (!(rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV))
                        return TXRX_CONTINUE;

                hdrlen = ieee80211_get_hdrlen(rx->fc);

                if (rx->skb->len < 8 + hdrlen)
                        return TXRX_DROP; /* TODO: count this? */

                /*
                 * no need to call ieee80211_wep_get_keyidx,
                 * it verifies a bunch of things we've done already
                 */
                keyidx = rx->skb->data[hdrlen + 3] >> 6;

                rx->key = rcu_dereference(rx->sdata->keys[keyidx]);

                /*
                 * RSNA-protected unicast frames should always be sent with
                 * pairwise or station-to-station keys, but for WEP we allow
                 * using a key index as well.
                 */
                if (rx->key && rx->key->conf.alg != ALG_WEP &&
                    !is_multicast_ether_addr(hdr->addr1))
                        rx->key = NULL;
        }

        if (rx->key) {
                rx->key->tx_rx_count++;
                if (unlikely(rx->local->key_tx_rx_threshold &&
                             rx->key->tx_rx_count >
                             rx->local->key_tx_rx_threshold)) {
                        ieee80211_key_threshold_notify(rx->dev, rx->key,
                                                       rx->sta);
                }
        }

        return TXRX_CONTINUE;
}

static void ap_sta_ps_start(struct net_device *dev, struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata;
        sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);

        if (sdata->bss)
                atomic_inc(&sdata->bss->num_sta_ps);
        sta->flags |= WLAN_STA_PS;
        sta->pspoll = 0;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        printk(KERN_DEBUG "%s: STA " MAC_FMT " aid %d enters power "
               "save mode\n", dev->name, MAC_ARG(sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
}

static int ap_sta_ps_end(struct net_device *dev, struct sta_info *sta)
{
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct sk_buff *skb;
        int sent = 0;
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_tx_packet_data *pkt_data;

        sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
        if (sdata->bss)
                atomic_dec(&sdata->bss->num_sta_ps);
        sta->flags &= ~(WLAN_STA_PS | WLAN_STA_TIM);
        sta->pspoll = 0;
        if (!skb_queue_empty(&sta->ps_tx_buf)) {
                if (local->ops->set_tim)
                        local->ops->set_tim(local_to_hw(local), sta->aid, 0);
                if (sdata->bss)
                        bss_tim_clear(local, sdata->bss, sta->aid);
        }
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        printk(KERN_DEBUG "%s: STA " MAC_FMT " aid %d exits power "
               "save mode\n", dev->name, MAC_ARG(sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
        /* Send all buffered frames to the station */
        while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
                pkt_data = (struct ieee80211_tx_packet_data *) skb->cb;
                sent++;
                pkt_data->flags |= IEEE80211_TXPD_REQUEUE;
                dev_queue_xmit(skb);
        }
        while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
                pkt_data = (struct ieee80211_tx_packet_data *) skb->cb;
                local->total_ps_buffered--;
                sent++;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
                printk(KERN_DEBUG "%s: STA " MAC_FMT " aid %d send PS frame "
                       "since STA not sleeping anymore\n", dev->name,
                       MAC_ARG(sta->addr), sta->aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
                pkt_data->flags |= IEEE80211_TXPD_REQUEUE;
                dev_queue_xmit(skb);
        }

        return sent;
}

static ieee80211_txrx_result
ieee80211_rx_h_sta_process(struct ieee80211_txrx_data *rx)
{
        struct sta_info *sta = rx->sta;
        struct net_device *dev = rx->dev;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;

        if (!sta)
                return TXRX_CONTINUE;

        /* Update last_rx only for IBSS packets which are for the current
         * BSSID to avoid keeping the current IBSS network alive in cases where
         * other STAs are using different BSSID. */
        if (rx->sdata->type == IEEE80211_IF_TYPE_IBSS) {
                u8 *bssid = ieee80211_get_bssid(hdr, rx->skb->len);
                if (compare_ether_addr(bssid, rx->sdata->u.sta.bssid) == 0)
                        sta->last_rx = jiffies;
        } else
        if (!is_multicast_ether_addr(hdr->addr1) ||
            rx->sdata->type == IEEE80211_IF_TYPE_STA) {
                /* Update last_rx only for unicast frames in order to prevent
                 * the Probe Request frames (the only broadcast frames from a
                 * STA in infrastructure mode) from keeping a connection alive.
                 */
                sta->last_rx = jiffies;
        }

        if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
                return TXRX_CONTINUE;

        sta->rx_fragments++;
        sta->rx_bytes += rx->skb->len;
        sta->last_rssi = rx->u.rx.status->ssi;
        sta->last_signal = rx->u.rx.status->signal;
        sta->last_noise = rx->u.rx.status->noise;

        if (!(rx->fc & IEEE80211_FCTL_MOREFRAGS)) {
                /* Change STA power saving mode only in the end of a frame
                 * exchange sequence */
                if ((sta->flags & WLAN_STA_PS) && !(rx->fc & IEEE80211_FCTL_PM))
                        rx->u.rx.sent_ps_buffered += ap_sta_ps_end(dev, sta);
                else if (!(sta->flags & WLAN_STA_PS) &&
                         (rx->fc & IEEE80211_FCTL_PM))
                        ap_sta_ps_start(dev, sta);
        }

        /* Drop data::nullfunc frames silently, since they are used only to
         * control station power saving mode. */
        if ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
            (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_NULLFUNC) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);
                /* Update counter and free packet here to avoid counting this
                 * as a dropped packed. */
                sta->rx_packets++;
                dev_kfree_skb(rx->skb);
                return TXRX_QUEUED;
        }

        return TXRX_CONTINUE;
} /* ieee80211_rx_h_sta_process */

static ieee80211_txrx_result
ieee80211_rx_h_wep_weak_iv_detection(struct ieee80211_txrx_data *rx)
{
        if (!rx->sta || !(rx->fc & IEEE80211_FCTL_PROTECTED) ||
            (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
            !rx->key || rx->key->conf.alg != ALG_WEP ||
            !(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
                return TXRX_CONTINUE;

        /* Check for weak IVs, if hwaccel did not remove IV from the frame */
        if ((rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV) ||
            !(rx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
                if (ieee80211_wep_is_weak_iv(rx->skb, rx->key))
                        rx->sta->wep_weak_iv_count++;

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_wep_decrypt(struct ieee80211_txrx_data *rx)
{
        if ((rx->key && rx->key->conf.alg != ALG_WEP) ||
            !(rx->fc & IEEE80211_FCTL_PROTECTED) ||
            ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA &&
             ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
              (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH)))
                return TXRX_CONTINUE;

        if (!rx->key) {
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: RX WEP frame, but no key set\n",
                               rx->dev->name);
                return TXRX_DROP;
        }

        if (!(rx->u.rx.status->flag & RX_FLAG_DECRYPTED) ||
            !(rx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
                if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: RX WEP frame, decrypt "
                                       "failed\n", rx->dev->name);
                        return TXRX_DROP;
                }
        } else if (rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV) {
                ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
                /* remove ICV */
                skb_trim(rx->skb, rx->skb->len - 4);
        }

        return TXRX_CONTINUE;
}

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_add(struct ieee80211_sub_if_data *sdata,
                         unsigned int frag, unsigned int seq, int rx_queue,
                         struct sk_buff **skb)
{
        struct ieee80211_fragment_entry *entry;
        int idx;

        idx = sdata->fragment_next;
        entry = &sdata->fragments[sdata->fragment_next++];
        if (sdata->fragment_next >= IEEE80211_FRAGMENT_MAX)
                sdata->fragment_next = 0;

        if (!skb_queue_empty(&entry->skb_list)) {
#ifdef CONFIG_MAC80211_DEBUG
                struct ieee80211_hdr *hdr =
                        (struct ieee80211_hdr *) entry->skb_list.next->data;
                printk(KERN_DEBUG "%s: RX reassembly removed oldest "
                       "fragment entry (idx=%d age=%lu seq=%d last_frag=%d "
                       "addr1=" MAC_FMT " addr2=" MAC_FMT "\n",
                       sdata->dev->name, idx,
                       jiffies - entry->first_frag_time, entry->seq,
                       entry->last_frag, MAC_ARG(hdr->addr1),
                       MAC_ARG(hdr->addr2));
#endif /* CONFIG_MAC80211_DEBUG */
                __skb_queue_purge(&entry->skb_list);
        }

        __skb_queue_tail(&entry->skb_list, *skb); /* no need for locking */
        *skb = NULL;
        entry->first_frag_time = jiffies;
        entry->seq = seq;
        entry->rx_queue = rx_queue;
        entry->last_frag = frag;
        entry->ccmp = 0;
        entry->extra_len = 0;

        return entry;
}

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_find(struct ieee80211_sub_if_data *sdata,
                          u16 fc, unsigned int frag, unsigned int seq,
                          int rx_queue, struct ieee80211_hdr *hdr)
{
        struct ieee80211_fragment_entry *entry;
        int i, idx;

        idx = sdata->fragment_next;
        for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++) {
                struct ieee80211_hdr *f_hdr;
                u16 f_fc;

                idx--;
                if (idx < 0)
                        idx = IEEE80211_FRAGMENT_MAX - 1;

                entry = &sdata->fragments[idx];
                if (skb_queue_empty(&entry->skb_list) || entry->seq != seq ||
                    entry->rx_queue != rx_queue ||
                    entry->last_frag + 1 != frag)
                        continue;

                f_hdr = (struct ieee80211_hdr *) entry->skb_list.next->data;
                f_fc = le16_to_cpu(f_hdr->frame_control);

                if ((fc & IEEE80211_FCTL_FTYPE) != (f_fc & IEEE80211_FCTL_FTYPE) ||
                    compare_ether_addr(hdr->addr1, f_hdr->addr1) != 0 ||
                    compare_ether_addr(hdr->addr2, f_hdr->addr2) != 0)
                        continue;

                if (entry->first_frag_time + 2 * HZ < jiffies) {
                        __skb_queue_purge(&entry->skb_list);
                        continue;
                }
                return entry;
        }

        return NULL;
}

static ieee80211_txrx_result
ieee80211_rx_h_defragment(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_hdr *hdr;
        u16 sc;
        unsigned int frag, seq;
        struct ieee80211_fragment_entry *entry;
        struct sk_buff *skb;

        hdr = (struct ieee80211_hdr *) rx->skb->data;
        sc = le16_to_cpu(hdr->seq_ctrl);
        frag = sc & IEEE80211_SCTL_FRAG;

        if (likely((!(rx->fc & IEEE80211_FCTL_MOREFRAGS) && frag == 0) ||
                   (rx->skb)->len < 24 ||
                   is_multicast_ether_addr(hdr->addr1))) {
                /* not fragmented */
                goto out;
        }
        I802_DEBUG_INC(rx->local->rx_handlers_fragments);

        seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

        if (frag == 0) {
                /* This is the first fragment of a new frame. */
                entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
                                                 rx->u.rx.queue, &(rx->skb));
                if (rx->key && rx->key->conf.alg == ALG_CCMP &&
                    (rx->fc & IEEE80211_FCTL_PROTECTED)) {
                        /* Store CCMP PN so that we can verify that the next
                         * fragment has a sequential PN value. */
                        entry->ccmp = 1;
                        memcpy(entry->last_pn,
                               rx->key->u.ccmp.rx_pn[rx->u.rx.queue],
                               CCMP_PN_LEN);
                }
                return TXRX_QUEUED;
        }

        /* This is a fragment for a frame that should already be pending in
         * fragment cache. Add this fragment to the end of the pending entry.
         */
        entry = ieee80211_reassemble_find(rx->sdata, rx->fc, frag, seq,
                                          rx->u.rx.queue, hdr);
        if (!entry) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
                return TXRX_DROP;
        }

        /* Verify that MPDUs within one MSDU have sequential PN values.
         * (IEEE 802.11i, 8.3.3.4.5) */
        if (entry->ccmp) {
                int i;
                u8 pn[CCMP_PN_LEN], *rpn;
                if (!rx->key || rx->key->conf.alg != ALG_CCMP)
                        return TXRX_DROP;
                memcpy(pn, entry->last_pn, CCMP_PN_LEN);
                for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
                        pn[i]++;
                        if (pn[i])
                                break;
                }
                rpn = rx->key->u.ccmp.rx_pn[rx->u.rx.queue];
                if (memcmp(pn, rpn, CCMP_PN_LEN) != 0) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: defrag: CCMP PN not "
                                       "sequential A2=" MAC_FMT
                                       " PN=%02x%02x%02x%02x%02x%02x "
                                       "(expected %02x%02x%02x%02x%02x%02x)\n",
                                       rx->dev->name, MAC_ARG(hdr->addr2),
                                       rpn[0], rpn[1], rpn[2], rpn[3], rpn[4],
                                       rpn[5], pn[0], pn[1], pn[2], pn[3],
                                       pn[4], pn[5]);
                        return TXRX_DROP;
                }
                memcpy(entry->last_pn, pn, CCMP_PN_LEN);
        }

        skb_pull(rx->skb, ieee80211_get_hdrlen(rx->fc));
        __skb_queue_tail(&entry->skb_list, rx->skb);
        entry->last_frag = frag;
        entry->extra_len += rx->skb->len;
        if (rx->fc & IEEE80211_FCTL_MOREFRAGS) {
                rx->skb = NULL;
                return TXRX_QUEUED;
        }

        rx->skb = __skb_dequeue(&entry->skb_list);
        if (skb_tailroom(rx->skb) < entry->extra_len) {
                I802_DEBUG_INC(rx->local->rx_expand_skb_head2);
                if (unlikely(pskb_expand_head(rx->skb, 0, entry->extra_len,
                                              GFP_ATOMIC))) {
                        I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
                        __skb_queue_purge(&entry->skb_list);
                        return TXRX_DROP;
                }
        }
        while ((skb = __skb_dequeue(&entry->skb_list))) {
                memcpy(skb_put(rx->skb, skb->len), skb->data, skb->len);
                dev_kfree_skb(skb);
        }

        /* Complete frame has been reassembled - process it now */
        rx->flags |= IEEE80211_TXRXD_FRAGMENTED;

 out:
        if (rx->sta)
                rx->sta->rx_packets++;
        if (is_multicast_ether_addr(hdr->addr1))
                rx->local->dot11MulticastReceivedFrameCount++;
        else
                ieee80211_led_rx(rx->local);
        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_ps_poll(struct ieee80211_txrx_data *rx)
{
        struct sk_buff *skb;
        int no_pending_pkts;

        if (likely(!rx->sta ||
                   (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_CTL ||
                   (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_PSPOLL ||
                   !(rx->flags & IEEE80211_TXRXD_RXRA_MATCH)))
                return TXRX_CONTINUE;

        skb = skb_dequeue(&rx->sta->tx_filtered);
        if (!skb) {
                skb = skb_dequeue(&rx->sta->ps_tx_buf);
                if (skb)
                        rx->local->total_ps_buffered--;
        }
        no_pending_pkts = skb_queue_empty(&rx->sta->tx_filtered) &&
                skb_queue_empty(&rx->sta->ps_tx_buf);

        if (skb) {
                struct ieee80211_hdr *hdr =
                        (struct ieee80211_hdr *) skb->data;

                /* tell TX path to send one frame even though the STA may
                 * still remain is PS mode after this frame exchange */
                rx->sta->pspoll = 1;

#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
                printk(KERN_DEBUG "STA " MAC_FMT " aid %d: PS Poll (entries "
                       "after %d)\n",
                       MAC_ARG(rx->sta->addr), rx->sta->aid,
                       skb_queue_len(&rx->sta->ps_tx_buf));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

                /* Use MoreData flag to indicate whether there are more
                 * buffered frames for this STA */
                if (no_pending_pkts) {
                        hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
                        rx->sta->flags &= ~WLAN_STA_TIM;
                } else
                        hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);

                dev_queue_xmit(skb);

                if (no_pending_pkts) {
                        if (rx->local->ops->set_tim)
                                rx->local->ops->set_tim(local_to_hw(rx->local),
                                                       rx->sta->aid, 0);
                        if (rx->sdata->bss)
                                bss_tim_clear(rx->local, rx->sdata->bss, rx->sta->aid);
                }
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        } else if (!rx->u.rx.sent_ps_buffered) {
                printk(KERN_DEBUG "%s: STA " MAC_FMT " sent PS Poll even "
                       "though there is no buffered frames for it\n",
                       rx->dev->name, MAC_ARG(rx->sta->addr));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

        }

        /* Free PS Poll skb here instead of returning TXRX_DROP that would
         * count as an dropped frame. */
        dev_kfree_skb(rx->skb);

        return TXRX_QUEUED;
}

static ieee80211_txrx_result
ieee80211_rx_h_remove_qos_control(struct ieee80211_txrx_data *rx)
{
        u16 fc = rx->fc;
        u8 *data = rx->skb->data;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) data;

        if (!WLAN_FC_IS_QOS_DATA(fc))
                return TXRX_CONTINUE;

        /* remove the qos control field, update frame type and meta-data */
        memmove(data + 2, data, ieee80211_get_hdrlen(fc) - 2);
        hdr = (struct ieee80211_hdr *) skb_pull(rx->skb, 2);
        /* change frame type to non QOS */
        rx->fc = fc &= ~IEEE80211_STYPE_QOS_DATA;
        hdr->frame_control = cpu_to_le16(fc);

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_802_1x_pae(struct ieee80211_txrx_data *rx)
{
        if (rx->sdata->eapol && ieee80211_is_eapol(rx->skb) &&
            rx->sdata->type != IEEE80211_IF_TYPE_STA &&
            (rx->flags & IEEE80211_TXRXD_RXRA_MATCH)) {
                /* Pass both encrypted and unencrypted EAPOL frames to user
                 * space for processing. */
                if (!rx->local->apdev)
                        return TXRX_DROP;
                ieee80211_rx_mgmt(rx->local, rx->skb, rx->u.rx.status,
                                  ieee80211_msg_normal);
                return TXRX_QUEUED;
        }

        if (unlikely(rx->sdata->ieee802_1x &&
                     (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
                     (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_NULLFUNC &&
                     (!rx->sta || !(rx->sta->flags & WLAN_STA_AUTHORIZED)) &&
                     !ieee80211_is_eapol(rx->skb))) {
#ifdef CONFIG_MAC80211_DEBUG
                struct ieee80211_hdr *hdr =
                        (struct ieee80211_hdr *) rx->skb->data;
                printk(KERN_DEBUG "%s: dropped frame from " MAC_FMT
                       " (unauthorized port)\n", rx->dev->name,
                       MAC_ARG(hdr->addr2));
#endif /* CONFIG_MAC80211_DEBUG */
                return TXRX_DROP;
        }

        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_drop_unencrypted(struct ieee80211_txrx_data *rx)
{
        /*
         * Pass through unencrypted frames if the hardware might have
         * decrypted them already without telling us, but that can only
         * be true if we either didn't find a key or the found key is
         * uploaded to the hardware.
         */
        if ((rx->local->hw.flags & IEEE80211_HW_DEVICE_HIDES_WEP) &&
            (!rx->key || (rx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)))
                return TXRX_CONTINUE;

        /* Drop unencrypted frames if key is set. */
        if (unlikely(!(rx->fc & IEEE80211_FCTL_PROTECTED) &&
                     (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
                     (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_NULLFUNC &&
                     (rx->key || rx->sdata->drop_unencrypted) &&
                     (rx->sdata->eapol == 0 ||
                      !ieee80211_is_eapol(rx->skb)))) {
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: RX non-WEP frame, but expected "
                               "encryption\n", rx->dev->name);
                return TXRX_DROP;
        }
        return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_rx_h_data(struct ieee80211_txrx_data *rx)
{
        struct net_device *dev = rx->dev;
        struct ieee80211_local *local = rx->local;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
        u16 fc, hdrlen, ethertype;
        u8 *payload;
        u8 dst[ETH_ALEN];
        u8 src[ETH_ALEN];
        struct sk_buff *skb = rx->skb, *skb2;
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);

        fc = rx->fc;
        if (unlikely((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA))
                return TXRX_CONTINUE;

        if (unlikely(!WLAN_FC_DATA_PRESENT(fc)))
                return TXRX_DROP;

        hdrlen = ieee80211_get_hdrlen(fc);

        /* convert IEEE 802.11 header + possible LLC headers into Ethernet
         * header
         * IEEE 802.11 address fields:
         * ToDS FromDS Addr1 Addr2 Addr3 Addr4
         *   0     0   DA    SA    BSSID n/a
         *   0     1   DA    BSSID SA    n/a
         *   1     0   BSSID SA    DA    n/a
         *   1     1   RA    TA    DA    SA
         */

        switch (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
        case IEEE80211_FCTL_TODS:
                /* BSSID SA DA */
                memcpy(dst, hdr->addr3, ETH_ALEN);
                memcpy(src, hdr->addr2, ETH_ALEN);

                if (unlikely(sdata->type != IEEE80211_IF_TYPE_AP &&
                             sdata->type != IEEE80211_IF_TYPE_VLAN)) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: dropped ToDS frame "
                                       "(BSSID=" MAC_FMT
                                       " SA=" MAC_FMT
                                       " DA=" MAC_FMT ")\n",
                                       dev->name,
                                       MAC_ARG(hdr->addr1),
                                       MAC_ARG(hdr->addr2),
                                       MAC_ARG(hdr->addr3));
                        return TXRX_DROP;
                }
                break;
        case (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
                /* RA TA DA SA */
                memcpy(dst, hdr->addr3, ETH_ALEN);
                memcpy(src, hdr->addr4, ETH_ALEN);

                if (unlikely(sdata->type != IEEE80211_IF_TYPE_WDS)) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: dropped FromDS&ToDS "
                                       "frame (RA=" MAC_FMT
                                       " TA=" MAC_FMT " DA=" MAC_FMT
                                       " SA=" MAC_FMT ")\n",
                                       rx->dev->name,
                                       MAC_ARG(hdr->addr1),
                                       MAC_ARG(hdr->addr2),
                                       MAC_ARG(hdr->addr3),
                                       MAC_ARG(hdr->addr4));
                        return TXRX_DROP;
                }
                break;
        case IEEE80211_FCTL_FROMDS:
                /* DA BSSID SA */
                memcpy(dst, hdr->addr1, ETH_ALEN);
                memcpy(src, hdr->addr3, ETH_ALEN);

                if (sdata->type != IEEE80211_IF_TYPE_STA ||
                    (is_multicast_ether_addr(dst) &&
                     !compare_ether_addr(src, dev->dev_addr)))
                        return TXRX_DROP;
                break;
        case 0:
                /* DA SA BSSID */
                memcpy(dst, hdr->addr1, ETH_ALEN);
                memcpy(src, hdr->addr2, ETH_ALEN);

                if (sdata->type != IEEE80211_IF_TYPE_IBSS) {
                        if (net_ratelimit()) {
                                printk(KERN_DEBUG "%s: dropped IBSS frame (DA="
                                       MAC_FMT " SA=" MAC_FMT " BSSID=" MAC_FMT
                                       ")\n",
                                       dev->name, MAC_ARG(hdr->addr1),
                                       MAC_ARG(hdr->addr2),
                                       MAC_ARG(hdr->addr3));
                        }
                        return TXRX_DROP;
                }
                break;
        }

        payload = skb->data + hdrlen;

        if (unlikely(skb->len - hdrlen < 8)) {
                if (net_ratelimit()) {
                        printk(KERN_DEBUG "%s: RX too short data frame "
                               "payload\n", dev->name);
                }
                return TXRX_DROP;
        }

        ethertype = (payload[6] << 8) | payload[7];

        if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
                    ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
                   compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
                /* remove RFC1042 or Bridge-Tunnel encapsulation and
                 * replace EtherType */
                skb_pull(skb, hdrlen + 6);
                memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
                memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
        } else {
                struct ethhdr *ehdr;
                __be16 len;
                skb_pull(skb, hdrlen);
                len = htons(skb->len);
                ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
                memcpy(ehdr->h_dest, dst, ETH_ALEN);
                memcpy(ehdr->h_source, src, ETH_ALEN);
                ehdr->h_proto = len;
        }
        skb->dev = dev;

        skb2 = NULL;

        sdata->stats.rx_packets++;
        sdata->stats.rx_bytes += skb->len;

        if (local->bridge_packets && (sdata->type == IEEE80211_IF_TYPE_AP
            || sdata->type == IEEE80211_IF_TYPE_VLAN) &&
            (rx->flags & IEEE80211_TXRXD_RXRA_MATCH)) {
                if (is_multicast_ether_addr(skb->data)) {
                        /* send multicast frames both to higher layers in
                         * local net stack and back to the wireless media */
                        skb2 = skb_copy(skb, GFP_ATOMIC);
                        if (!skb2 && net_ratelimit())
                                printk(KERN_DEBUG "%s: failed to clone "
                                       "multicast frame\n", dev->name);
                } else {
                        struct sta_info *dsta;
                        dsta = sta_info_get(local, skb->data);
                        if (dsta && !dsta->dev) {
                                if (net_ratelimit())
                                        printk(KERN_DEBUG "Station with null "
                                               "dev structure!\n");
                        } else if (dsta && dsta->dev == dev) {
                                /* Destination station is associated to this
                                 * AP, so send the frame directly to it and
                                 * do not pass the frame to local net stack.
                                 */
                                skb2 = skb;
                                skb = NULL;
                        }
                        if (dsta)
                                sta_info_put(dsta);
                }
        }

        if (skb) {
                /* deliver to local stack */
                skb->protocol = eth_type_trans(skb, dev);
                memset(skb->cb, 0, sizeof(skb->cb));
                netif_rx(skb);
        }

        if (skb2) {
                /* send to wireless media */
                skb2->protocol = __constant_htons(ETH_P_802_3);
                skb_set_network_header(skb2, 0);
                skb_set_mac_header(skb2, 0);
                dev_queue_xmit(skb2);
        }

        return TXRX_QUEUED;
}

static ieee80211_txrx_result
ieee80211_rx_h_mgmt(struct ieee80211_txrx_data *rx)
{
        struct ieee80211_sub_if_data *sdata;

        if (!(rx->flags & IEEE80211_TXRXD_RXRA_MATCH))
                return TXRX_DROP;

        sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
        if ((sdata->type == IEEE80211_IF_TYPE_STA ||
             sdata->type == IEEE80211_IF_TYPE_IBSS) &&
            !rx->local->user_space_mlme) {
                ieee80211_sta_rx_mgmt(rx->dev, rx->skb, rx->u.rx.status);
        } else {
                /* Management frames are sent to hostapd for processing */
                if (!rx->local->apdev)
                        return TXRX_DROP;
                ieee80211_rx_mgmt(rx->local, rx->skb, rx->u.rx.status,
                                  ieee80211_msg_normal);
        }
        return TXRX_QUEUED;
}

static inline ieee80211_txrx_result __ieee80211_invoke_rx_handlers(
                                struct ieee80211_local *local,
                                ieee80211_rx_handler *handlers,
                                struct ieee80211_txrx_data *rx,
                                struct sta_info *sta)
{
        ieee80211_rx_handler *handler;
        ieee80211_txrx_result res = TXRX_DROP;

        for (handler = handlers; *handler != NULL; handler++) {
                res = (*handler)(rx);

                switch (res) {
                case TXRX_CONTINUE:
                        continue;
                case TXRX_DROP:
                        I802_DEBUG_INC(local->rx_handlers_drop);
                        if (sta)
                                sta->rx_dropped++;
                        break;
                case TXRX_QUEUED:
                        I802_DEBUG_INC(local->rx_handlers_queued);
                        break;
                }
                break;
        }

        if (res == TXRX_DROP)
                dev_kfree_skb(rx->skb);
        return res;
}

static inline void ieee80211_invoke_rx_handlers(struct ieee80211_local *local,
                                                ieee80211_rx_handler *handlers,
                                                struct ieee80211_txrx_data *rx,
                                                struct sta_info *sta)
{
        if (__ieee80211_invoke_rx_handlers(local, handlers, rx, sta) ==
            TXRX_CONTINUE)
                dev_kfree_skb(rx->skb);
}

static void ieee80211_rx_michael_mic_report(struct net_device *dev,
                                            struct ieee80211_hdr *hdr,
                                            struct sta_info *sta,
                                            struct ieee80211_txrx_data *rx)
{
        int keyidx, hdrlen;

        hdrlen = ieee80211_get_hdrlen_from_skb(rx->skb);
        if (rx->skb->len >= hdrlen + 4)
                keyidx = rx->skb->data[hdrlen + 3] >> 6;
        else
                keyidx = -1;

        /* TODO: verify that this is not triggered by fragmented
         * frames (hw does not verify MIC for them). */
        if (net_ratelimit())
                printk(KERN_DEBUG "%s: TKIP hwaccel reported Michael MIC "
                       "failure from " MAC_FMT " to " MAC_FMT " keyidx=%d\n",
                       dev->name, MAC_ARG(hdr->addr2), MAC_ARG(hdr->addr1),
                       keyidx);

        if (!sta) {
                /* Some hardware versions seem to generate incorrect
                 * Michael MIC reports; ignore them to avoid triggering
                 * countermeasures. */
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                               "error for unknown address " MAC_FMT "\n",
                               dev->name, MAC_ARG(hdr->addr2));
                goto ignore;
        }

        if (!(rx->fc & IEEE80211_FCTL_PROTECTED)) {
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                               "error for a frame with no ISWEP flag (src "
                               MAC_FMT ")\n", dev->name, MAC_ARG(hdr->addr2));
                goto ignore;
        }

        if ((rx->local->hw.flags & IEEE80211_HW_WEP_INCLUDE_IV) &&
            rx->sdata->type == IEEE80211_IF_TYPE_AP && keyidx) {
                /* AP with Pairwise keys support 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 BSS. */
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: ignored Michael MIC error for "
                               "a frame with non-zero keyidx (%d)"
                               " (src " MAC_FMT ")\n", dev->name, keyidx,
                               MAC_ARG(hdr->addr2));
                goto ignore;
        }

        if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA &&
            ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
             (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH)) {
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: ignored spurious Michael MIC "
                               "error for a frame that cannot be encrypted "
                               "(fc=0x%04x) (src " MAC_FMT ")\n",
                               dev->name, rx->fc, MAC_ARG(hdr->addr2));
                goto ignore;
        }

        /* TODO: consider verifying the MIC error report with software
         * implementation if we get too many spurious reports from the
         * hardware. */

        mac80211_ev_michael_mic_failure(rx->dev, keyidx, hdr);
 ignore:
        dev_kfree_skb(rx->skb);
        rx->skb = NULL;
}

ieee80211_rx_handler ieee80211_rx_handlers[] =
{
        ieee80211_rx_h_if_stats,
        ieee80211_rx_h_monitor,
        ieee80211_rx_h_passive_scan,
        ieee80211_rx_h_check,
        ieee80211_rx_h_load_key,
        ieee80211_rx_h_sta_process,
        ieee80211_rx_h_ccmp_decrypt,
        ieee80211_rx_h_tkip_decrypt,
        ieee80211_rx_h_wep_weak_iv_detection,
        ieee80211_rx_h_wep_decrypt,
        ieee80211_rx_h_defragment,
        ieee80211_rx_h_ps_poll,
        ieee80211_rx_h_michael_mic_verify,
        /* this must be after decryption - so header is counted in MPDU mic
         * must be before pae and data, so QOS_DATA format frames
         * are not passed to user space by these functions
         */
        ieee80211_rx_h_remove_qos_control,
        ieee80211_rx_h_802_1x_pae,
        ieee80211_rx_h_drop_unencrypted,
        ieee80211_rx_h_data,
        ieee80211_rx_h_mgmt,
        NULL
};

/* main receive path */

static int prepare_for_handlers(struct ieee80211_sub_if_data *sdata,
                                u8 *bssid, struct ieee80211_txrx_data *rx,
                                struct ieee80211_hdr *hdr)
{
        int multicast = is_multicast_ether_addr(hdr->addr1);

        switch (sdata->type) {
        case IEEE80211_IF_TYPE_STA:
                if (!bssid)
                        return 0;
                if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                        if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
                } else if (!multicast &&
                           compare_ether_addr(sdata->dev->dev_addr,
                                              hdr->addr1) != 0) {
                        if (!(sdata->flags & IEEE80211_SDATA_PROMISC))
                                return 0;
                        rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
                }
                break;
        case IEEE80211_IF_TYPE_IBSS:
                if (!bssid)
                        return 0;
                if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                        if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
                } else if (!multicast &&
                           compare_ether_addr(sdata->dev->dev_addr,
                                              hdr->addr1) != 0) {
                        if (!(sdata->flags & IEEE80211_SDATA_PROMISC))
                                return 0;
                        rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
                } else if (!rx->sta)
                        rx->sta = ieee80211_ibss_add_sta(sdata->dev, rx->skb,
                                                         bssid, hdr->addr2);
                break;
        case IEEE80211_IF_TYPE_AP:
                if (!bssid) {
                        if (compare_ether_addr(sdata->dev->dev_addr,
                                               hdr->addr1))
                                return 0;
                } else if (!ieee80211_bssid_match(bssid,
                                        sdata->dev->dev_addr)) {
                        if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
                }
                if (sdata->dev == sdata->local->mdev &&
                    !(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
                        /* do not receive anything via
                         * master device when not scanning */
                        return 0;
                break;
        case IEEE80211_IF_TYPE_WDS:
                if (bssid ||
                    (rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)
                        return 0;
                if (compare_ether_addr(sdata->u.wds.remote_addr, hdr->addr2))
                        return 0;
                break;
        }

        return 1;
}

/*
 * This is the receive path handler. It is called by a low level driver when an
 * 802.11 MPDU is received from the hardware.
 */
void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
                    struct ieee80211_rx_status *status)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_sub_if_data *sdata;
        struct sta_info *sta;
        struct ieee80211_hdr *hdr;
        struct ieee80211_txrx_data rx;
        u16 type;
        int radiotap_len = 0, prepres;
        struct ieee80211_sub_if_data *prev = NULL;
        struct sk_buff *skb_new;
        u8 *bssid;

        if (status->flag & RX_FLAG_RADIOTAP) {
                radiotap_len = ieee80211_get_radiotap_len(skb->data);
                skb_pull(skb, radiotap_len);
        }

        /*
         * key references are protected using RCU and this requires that
         * we are in a read-site RCU section during receive processing
         */
        rcu_read_lock();

        hdr = (struct ieee80211_hdr *) skb->data;
        memset(&rx, 0, sizeof(rx));
        rx.skb = skb;
        rx.local = local;

        rx.u.rx.status = status;
        rx.fc = skb->len >= 2 ? le16_to_cpu(hdr->frame_control) : 0;
        type = rx.fc & IEEE80211_FCTL_FTYPE;
        if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT)
                local->dot11ReceivedFragmentCount++;

        if (skb->len >= 16) {
                sta = rx.sta = sta_info_get(local, hdr->addr2);
                if (sta) {
                        rx.dev = rx.sta->dev;
                        rx.sdata = IEEE80211_DEV_TO_SUB_IF(rx.dev);
                }
        } else
                sta = rx.sta = NULL;

        if ((status->flag & RX_FLAG_MMIC_ERROR)) {
                ieee80211_rx_michael_mic_report(local->mdev, hdr, sta, &rx);
                goto end;
        }

        if (unlikely(local->sta_scanning))
                rx.flags |= IEEE80211_TXRXD_RXIN_SCAN;

        if (__ieee80211_invoke_rx_handlers(local, local->rx_pre_handlers, &rx,
                                           sta) != TXRX_CONTINUE)
                goto end;
        skb = rx.skb;

        skb_push(skb, radiotap_len);
        if (sta && !(sta->flags & (WLAN_STA_WDS | WLAN_STA_ASSOC_AP)) &&
            !local->iff_promiscs && !is_multicast_ether_addr(hdr->addr1)) {
                rx.flags |= IEEE80211_TXRXD_RXRA_MATCH;
                ieee80211_invoke_rx_handlers(local, local->rx_handlers, &rx,
                                             rx.sta);
                sta_info_put(sta);
                rcu_read_unlock();
                return;
        }

        bssid = ieee80211_get_bssid(hdr, skb->len - radiotap_len);

        read_lock(&local->sub_if_lock);
        list_for_each_entry(sdata, &local->sub_if_list, list) {
                rx.flags |= IEEE80211_TXRXD_RXRA_MATCH;

                if (!netif_running(sdata->dev))
                        continue;

                prepres = prepare_for_handlers(sdata, bssid, &rx, hdr);
                /* prepare_for_handlers can change sta */
                sta = rx.sta;

                if (!prepres)
                        continue;

                /*
                 * frame is destined for this interface, but if it's not
                 * also for the previous one we handle that after the
                 * loop to avoid copying the SKB once too much
                 */

                if (!prev) {
                        prev = sdata;
                        continue;
                }

                /*
                 * frame was destined for the previous interface
                 * so invoke RX handlers for it
                 */

                skb_new = skb_copy(skb, GFP_ATOMIC);
                if (!skb_new) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: failed to copy "
                                       "multicast frame for %s",
                                       local->mdev->name, prev->dev->name);
                        continue;
                }
                rx.skb = skb_new;
                rx.dev = prev->dev;
                rx.sdata = prev;
                ieee80211_invoke_rx_handlers(local, local->rx_handlers,
                                             &rx, sta);
                prev = sdata;
        }
        if (prev) {
                rx.skb = skb;
                rx.dev = prev->dev;
                rx.sdata = prev;
                ieee80211_invoke_rx_handlers(local, local->rx_handlers,
                                             &rx, sta);
        } else
                dev_kfree_skb(skb);
        read_unlock(&local->sub_if_lock);

 end:
        rcu_read_unlock();

        if (sta)
                sta_info_put(sta);
}
EXPORT_SYMBOL(__ieee80211_rx);

/* This is a version of the rx handler that can be called from hard irq
 * context. Post the skb on the queue and schedule the tasklet */
void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb,
                          struct ieee80211_rx_status *status)
{
        struct ieee80211_local *local = hw_to_local(hw);

        BUILD_BUG_ON(sizeof(struct ieee80211_rx_status) > sizeof(skb->cb));

        skb->dev = local->mdev;
        /* copy status into skb->cb for use by tasklet */
        memcpy(skb->cb, status, sizeof(*status));
        skb->pkt_type = IEEE80211_RX_MSG;
        skb_queue_tail(&local->skb_queue, skb);
        tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_rx_irqsafe);