rx.c

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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <[email protected]>
 * Copyright 2007-2010  Johannes Berg <[email protected]>
 *
 * 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/jiffies.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <net/mac80211.h>
#include <net/ieee80211_radiotap.h>
#include <asm/unaligned.h>

#include "ieee80211_i.h"
#include "driver-ops.h"
#include "led.h"
#include "mesh.h"
#include "wep.h"
#include "wpa.h"
#include "tkip.h"
#include "wme.h"
#include "rate.h"

/*
 * monitor mode reception
 *
 * This function cleans up the SKB, i.e. it removes all the stuff
 * only useful for monitoring.
 */
static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
                       struct sk_buff *skb)
{
    if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
        if (likely(skb->len > FCS_LEN))
            __pskb_trim(skb, skb->len - FCS_LEN);
        else {
            /* driver bug */
            WARN_ON(1);
            dev_kfree_skb(skb);
            skb = NULL;
        }
    }

    return skb;
}

static inline int should_drop_frame(struct sk_buff *skb,
                    int present_fcs_len)
{
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

    if (status->flag & (RX_FLAG_FAILED_FCS_CRC |
                RX_FLAG_FAILED_PLCP_CRC |
                RX_FLAG_AMPDU_IS_ZEROLEN))
        return 1;
    if (unlikely(skb->len < 16 + present_fcs_len))
        return 1;
    if (ieee80211_is_ctl(hdr->frame_control) &&
        !ieee80211_is_pspoll(hdr->frame_control) &&
        !ieee80211_is_back_req(hdr->frame_control))
        return 1;
    return 0;
}

static int
ieee80211_rx_radiotap_len(struct ieee80211_local *local,
              struct ieee80211_rx_status *status)
{
    int len;

    /* always present fields */
    len = sizeof(struct ieee80211_radiotap_header) + 9;

    if (status->flag & RX_FLAG_MACTIME_MPDU)
        len += 8;
    if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
        len += 1;

    if (len & 1) /* padding for RX_FLAGS if necessary */
        len++;

    if (status->flag & RX_FLAG_HT) /* HT info */
        len += 3;

    if (status->flag & RX_FLAG_AMPDU_DETAILS) {
        /* padding */
        while (len & 3)
            len++;
        len += 8;
    }

    return len;
}

/*
 * ieee80211_add_rx_radiotap_header - add radiotap header
 *
 * add a radiotap header containing all the fields which the hardware provided.
 */
static void
ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
                 struct sk_buff *skb,
                 struct ieee80211_rate *rate,
                 int rtap_len, bool has_fcs)
{
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_radiotap_header *rthdr;
    unsigned char *pos;
    u16 rx_flags = 0;

    rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
    memset(rthdr, 0, rtap_len);

    /* radiotap header, set always present flags */
    rthdr->it_present =
        cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                (1 << IEEE80211_RADIOTAP_CHANNEL) |
                (1 << IEEE80211_RADIOTAP_ANTENNA) |
                (1 << IEEE80211_RADIOTAP_RX_FLAGS));
    rthdr->it_len = cpu_to_le16(rtap_len);

    pos = (unsigned char *)(rthdr+1);

    /* the order of the following fields is important */

    /* IEEE80211_RADIOTAP_TSFT */
    if (status->flag & RX_FLAG_MACTIME_MPDU) {
        put_unaligned_le64(status->mactime, pos);
        rthdr->it_present |=
            cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
        pos += 8;
    }

    /* IEEE80211_RADIOTAP_FLAGS */
    if (has_fcs && (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS))
        *pos |= IEEE80211_RADIOTAP_F_FCS;
    if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
        *pos |= IEEE80211_RADIOTAP_F_BADFCS;
    if (status->flag & RX_FLAG_SHORTPRE)
        *pos |= IEEE80211_RADIOTAP_F_SHORTPRE;
    pos++;

    /* IEEE80211_RADIOTAP_RATE */
    if (!rate || status->flag & RX_FLAG_HT) {
        /*
         * Without rate information don't add it. If we have,
         * MCS information is a separate field in radiotap,
         * added below. The byte here is needed as padding
         * for the channel though, so initialise it to 0.
         */
        *pos = 0;
    } else {
        rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
        *pos = rate->bitrate / 5;
    }
    pos++;

    /* IEEE80211_RADIOTAP_CHANNEL */
    put_unaligned_le16(status->freq, pos);
    pos += 2;
    if (status->band == IEEE80211_BAND_5GHZ)
        put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ,
                   pos);
    else if (status->flag & RX_FLAG_HT)
        put_unaligned_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ,
                   pos);
    else if (rate && rate->flags & IEEE80211_RATE_ERP_G)
        put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,
                   pos);
    else if (rate)
        put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ,
                   pos);
    else
        put_unaligned_le16(IEEE80211_CHAN_2GHZ, pos);
    pos += 2;

    /* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */
    if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM &&
        !(status->flag & RX_FLAG_NO_SIGNAL_VAL)) {
        *pos = status->signal;
        rthdr->it_present |=
            cpu_to_le32(1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL);
        pos++;
    }

    /* IEEE80211_RADIOTAP_LOCK_QUALITY is missing */

    /* IEEE80211_RADIOTAP_ANTENNA */
    *pos = status->antenna;
    pos++;

    /* IEEE80211_RADIOTAP_DB_ANTNOISE is not used */

    /* IEEE80211_RADIOTAP_RX_FLAGS */
    /* ensure 2 byte alignment for the 2 byte field as required */
    if ((pos - (u8 *)rthdr) & 1)
        pos++;
    if (status->flag & RX_FLAG_FAILED_PLCP_CRC)
        rx_flags |= IEEE80211_RADIOTAP_F_RX_BADPLCP;
    put_unaligned_le16(rx_flags, pos);
    pos += 2;

    if (status->flag & RX_FLAG_HT) {
        rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_MCS);
        *pos++ = local->hw.radiotap_mcs_details;
        *pos = 0;
        if (status->flag & RX_FLAG_SHORT_GI)
            *pos |= IEEE80211_RADIOTAP_MCS_SGI;
        if (status->flag & RX_FLAG_40MHZ)
            *pos |= IEEE80211_RADIOTAP_MCS_BW_40;
        if (status->flag & RX_FLAG_HT_GF)
            *pos |= IEEE80211_RADIOTAP_MCS_FMT_GF;
        pos++;
        *pos++ = status->rate_idx;
    }

    if (status->flag & RX_FLAG_AMPDU_DETAILS) {
        u16 flags = 0;

        /* ensure 4 byte alignment */
        while ((pos - (u8 *)rthdr) & 3)
            pos++;
        rthdr->it_present |=
            cpu_to_le32(1 << IEEE80211_RADIOTAP_AMPDU_STATUS);
        put_unaligned_le32(status->ampdu_reference, pos);
        pos += 4;
        if (status->flag & RX_FLAG_AMPDU_REPORT_ZEROLEN)
            flags |= IEEE80211_RADIOTAP_AMPDU_REPORT_ZEROLEN;
        if (status->flag & RX_FLAG_AMPDU_IS_ZEROLEN)
            flags |= IEEE80211_RADIOTAP_AMPDU_IS_ZEROLEN;
        if (status->flag & RX_FLAG_AMPDU_LAST_KNOWN)
            flags |= IEEE80211_RADIOTAP_AMPDU_LAST_KNOWN;
        if (status->flag & RX_FLAG_AMPDU_IS_LAST)
            flags |= IEEE80211_RADIOTAP_AMPDU_IS_LAST;
        if (status->flag & RX_FLAG_AMPDU_DELIM_CRC_ERROR)
            flags |= IEEE80211_RADIOTAP_AMPDU_DELIM_CRC_ERR;
        if (status->flag & RX_FLAG_AMPDU_DELIM_CRC_KNOWN)
            flags |= IEEE80211_RADIOTAP_AMPDU_DELIM_CRC_KNOWN;
        put_unaligned_le16(flags, pos);
        pos += 2;
        if (status->flag & RX_FLAG_AMPDU_DELIM_CRC_KNOWN)
            *pos++ = status->ampdu_delimiter_crc;
        else
            *pos++ = 0;
        *pos++ = 0;
    }
}

/*
 * This function copies a received frame to all monitor interfaces and
 * returns a cleaned-up SKB that no longer includes the FCS nor the
 * radiotap header the driver might have added.
 */
static struct sk_buff *
ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
             struct ieee80211_rate *rate)
{
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(origskb);
    struct ieee80211_sub_if_data *sdata;
    int needed_headroom;
    struct sk_buff *skb, *skb2;
    struct net_device *prev_dev = NULL;
    int present_fcs_len = 0;

    /*
     * First, we may need to make a copy of the skb because
     *  (1) we need to modify it for radiotap (if not present), and
     *  (2) the other RX handlers will modify the skb we got.
     *
     * We don't need to, of course, if we aren't going to return
     * the SKB because it has a bad FCS/PLCP checksum.
     */

    /* room for the radiotap header based on driver features */
    needed_headroom = ieee80211_rx_radiotap_len(local, status);

    if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
        present_fcs_len = FCS_LEN;

    /* make sure hdr->frame_control is on the linear part */
    if (!pskb_may_pull(origskb, 2)) {
        dev_kfree_skb(origskb);
        return NULL;
    }

    if (!local->monitors) {
        if (should_drop_frame(origskb, present_fcs_len)) {
            dev_kfree_skb(origskb);
            return NULL;
        }

        return remove_monitor_info(local, origskb);
    }

    if (should_drop_frame(origskb, present_fcs_len)) {
        /* only need to expand headroom if necessary */
        skb = origskb;
        origskb = NULL;

        /*
         * This shouldn't trigger often because most devices have an
         * RX header they pull before we get here, and that should
         * be big enough for our radiotap information. We should
         * probably export the length to drivers so that we can have
         * them allocate enough headroom to start with.
         */
        if (skb_headroom(skb) < needed_headroom &&
            pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC)) {
            dev_kfree_skb(skb);
            return NULL;
        }
    } else {
        /*
         * Need to make a copy and possibly remove radiotap header
         * and FCS from the original.
         */
        skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC);

        origskb = remove_monitor_info(local, origskb);

        if (!skb)
            return origskb;
    }

    /* prepend radiotap information */
    ieee80211_add_rx_radiotap_header(local, skb, rate, needed_headroom,
                     true);

    skb_reset_mac_header(skb);
    skb->ip_summed = CHECKSUM_UNNECESSARY;
    skb->pkt_type = PACKET_OTHERHOST;
    skb->protocol = htons(ETH_P_802_2);

    list_for_each_entry_rcu(sdata, &local->interfaces, list) {
        if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
            continue;

        if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES)
            continue;

        if (!ieee80211_sdata_running(sdata))
            continue;

        if (prev_dev) {
            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (skb2) {
                skb2->dev = prev_dev;
                netif_receive_skb(skb2);
            }
        }

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

    if (prev_dev) {
        skb->dev = prev_dev;
        netif_receive_skb(skb);
    } else
        dev_kfree_skb(skb);

    return origskb;
}


static void ieee80211_parse_qos(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
    int tid, seqno_idx, security_idx;

    /* does the frame have a qos control field? */
    if (ieee80211_is_data_qos(hdr->frame_control)) {
        u8 *qc = ieee80211_get_qos_ctl(hdr);
        /* frame has qos control */
        tid = *qc & IEEE80211_QOS_CTL_TID_MASK;
        if (*qc & IEEE80211_QOS_CTL_A_MSDU_PRESENT)
            status->rx_flags |= IEEE80211_RX_AMSDU;

        seqno_idx = tid;
        security_idx = tid;
    } else {
        /*
         * IEEE 802.11-2007, 7.1.3.4.1 ("Sequence Number field"):
         *
         *  Sequence numbers for management frames, QoS data
         *  frames with a broadcast/multicast address in the
         *  Address 1 field, and all non-QoS data frames sent
         *  by QoS STAs are assigned using an additional single
         *  modulo-4096 counter, [...]
         *
         * We also use that counter for non-QoS STAs.
         */
        seqno_idx = NUM_RX_DATA_QUEUES;
        security_idx = 0;
        if (ieee80211_is_mgmt(hdr->frame_control))
            security_idx = NUM_RX_DATA_QUEUES;
        tid = 0;
    }

    rx->seqno_idx = seqno_idx;
    rx->security_idx = security_idx;
    /* 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;
}

static void ieee80211_verify_alignment(struct ieee80211_rx_data *rx)
{
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
    WARN_ONCE((unsigned long)rx->skb->data & 1,
          "unaligned packet at 0x%p\n", rx->skb->data);
#endif
}


/* rx handlers */

static int ieee80211_is_unicast_robust_mgmt_frame(struct sk_buff *skb)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

    if (skb->len < 24 || is_multicast_ether_addr(hdr->addr1))
        return 0;

    return ieee80211_is_robust_mgmt_frame(hdr);
}


static int ieee80211_is_multicast_robust_mgmt_frame(struct sk_buff *skb)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

    if (skb->len < 24 || !is_multicast_ether_addr(hdr->addr1))
        return 0;

    return ieee80211_is_robust_mgmt_frame(hdr);
}


/* Get the BIP key index from MMIE; return -1 if this is not a BIP frame */
static int ieee80211_get_mmie_keyidx(struct sk_buff *skb)
{
    struct ieee80211_mgmt *hdr = (struct ieee80211_mgmt *) skb->data;
    struct ieee80211_mmie *mmie;

    if (skb->len < 24 + sizeof(*mmie) ||
        !is_multicast_ether_addr(hdr->da))
        return -1;

    if (!ieee80211_is_robust_mgmt_frame((struct ieee80211_hdr *) hdr))
        return -1; /* not a robust management frame */

    mmie = (struct ieee80211_mmie *)
        (skb->data + skb->len - sizeof(*mmie));
    if (mmie->element_id != WLAN_EID_MMIE ||
        mmie->length != sizeof(*mmie) - 2)
        return -1;

    return le16_to_cpu(mmie->key_id);
}


static ieee80211_rx_result
ieee80211_rx_mesh_check(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    char *dev_addr = rx->sdata->vif.addr;

    if (ieee80211_is_data(hdr->frame_control)) {
        if (is_multicast_ether_addr(hdr->addr1)) {
            if (ieee80211_has_tods(hdr->frame_control) ||
                !ieee80211_has_fromds(hdr->frame_control))
                return RX_DROP_MONITOR;
            if (ether_addr_equal(hdr->addr3, dev_addr))
                return RX_DROP_MONITOR;
        } else {
            if (!ieee80211_has_a4(hdr->frame_control))
                return RX_DROP_MONITOR;
            if (ether_addr_equal(hdr->addr4, dev_addr))
                return RX_DROP_MONITOR;
        }
    }

    /* If there is not an established peer link and this is not a peer link
     * establisment frame, beacon or probe, drop the frame.
     */

    if (!rx->sta || sta_plink_state(rx->sta) != NL80211_PLINK_ESTAB) {
        struct ieee80211_mgmt *mgmt;

        if (!ieee80211_is_mgmt(hdr->frame_control))
            return RX_DROP_MONITOR;

        if (ieee80211_is_action(hdr->frame_control)) {
            u8 category;

            /* make sure category field is present */
            if (rx->skb->len < IEEE80211_MIN_ACTION_SIZE)
                return RX_DROP_MONITOR;

            mgmt = (struct ieee80211_mgmt *)hdr;
            category = mgmt->u.action.category;
            if (category != WLAN_CATEGORY_MESH_ACTION &&
                category != WLAN_CATEGORY_SELF_PROTECTED)
                return RX_DROP_MONITOR;
            return RX_CONTINUE;
        }

        if (ieee80211_is_probe_req(hdr->frame_control) ||
            ieee80211_is_probe_resp(hdr->frame_control) ||
            ieee80211_is_beacon(hdr->frame_control) ||
            ieee80211_is_auth(hdr->frame_control))
            return RX_CONTINUE;

        return RX_DROP_MONITOR;

    }

    return RX_CONTINUE;
}

#define SEQ_MODULO 0x1000
#define SEQ_MASK   0xfff

static inline int seq_less(u16 sq1, u16 sq2)
{
    return ((sq1 - sq2) & SEQ_MASK) > (SEQ_MODULO >> 1);
}

static inline u16 seq_inc(u16 sq)
{
    return (sq + 1) & SEQ_MASK;
}

static inline u16 seq_sub(u16 sq1, u16 sq2)
{
    return (sq1 - sq2) & SEQ_MASK;
}


static void ieee80211_release_reorder_frame(struct ieee80211_sub_if_data *sdata,
                        struct tid_ampdu_rx *tid_agg_rx,
                        int index)
{
    struct ieee80211_local *local = sdata->local;
    struct sk_buff *skb = tid_agg_rx->reorder_buf[index];
    struct ieee80211_rx_status *status;

    lockdep_assert_held(&tid_agg_rx->reorder_lock);

    if (!skb)
        goto no_frame;

    /* release the frame from the reorder ring buffer */
    tid_agg_rx->stored_mpdu_num--;
    tid_agg_rx->reorder_buf[index] = NULL;
    status = IEEE80211_SKB_RXCB(skb);
    status->rx_flags |= IEEE80211_RX_DEFERRED_RELEASE;
    skb_queue_tail(&local->rx_skb_queue, skb);

no_frame:
    tid_agg_rx->head_seq_num = seq_inc(tid_agg_rx->head_seq_num);
}

static void ieee80211_release_reorder_frames(struct ieee80211_sub_if_data *sdata,
                         struct tid_ampdu_rx *tid_agg_rx,
                         u16 head_seq_num)
{
    int index;

    lockdep_assert_held(&tid_agg_rx->reorder_lock);

    while (seq_less(tid_agg_rx->head_seq_num, head_seq_num)) {
        index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %
                            tid_agg_rx->buf_size;
        ieee80211_release_reorder_frame(sdata, tid_agg_rx, index);
    }
}

/*
 * Timeout (in jiffies) for skb's that are waiting in the RX reorder buffer. If
 * the skb was added to the buffer longer than this time ago, the earlier
 * frames that have not yet been received are assumed to be lost and the skb
 * can be released for processing. This may also release other skb's from the
 * reorder buffer if there are no additional gaps between the frames.
 *
 * Callers must hold tid_agg_rx->reorder_lock.
 */
#define HT_RX_REORDER_BUF_TIMEOUT (HZ / 10)

static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
                      struct tid_ampdu_rx *tid_agg_rx)
{
    int index, j;

    lockdep_assert_held(&tid_agg_rx->reorder_lock);

    /* release the buffer until next missing frame */
    index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %
                        tid_agg_rx->buf_size;
    if (!tid_agg_rx->reorder_buf[index] &&
        tid_agg_rx->stored_mpdu_num) {
        /*
         * No buffers ready to be released, but check whether any
         * frames in the reorder buffer have timed out.
         */
        int skipped = 1;
        for (j = (index + 1) % tid_agg_rx->buf_size; j != index;
             j = (j + 1) % tid_agg_rx->buf_size) {
            if (!tid_agg_rx->reorder_buf[j]) {
                skipped++;
                continue;
            }
            if (skipped &&
                !time_after(jiffies, tid_agg_rx->reorder_time[j] +
                    HT_RX_REORDER_BUF_TIMEOUT))
                goto set_release_timer;

            ht_dbg_ratelimited(sdata,
                       "release an RX reorder frame due to timeout on earlier frames\n");
            ieee80211_release_reorder_frame(sdata, tid_agg_rx, j);

            /*
             * Increment the head seq# also for the skipped slots.
             */
            tid_agg_rx->head_seq_num =
                (tid_agg_rx->head_seq_num + skipped) & SEQ_MASK;
            skipped = 0;
        }
    } else while (tid_agg_rx->reorder_buf[index]) {
        ieee80211_release_reorder_frame(sdata, tid_agg_rx, index);
        index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %
                            tid_agg_rx->buf_size;
    }

    if (tid_agg_rx->stored_mpdu_num) {
        j = index = seq_sub(tid_agg_rx->head_seq_num,
                    tid_agg_rx->ssn) % tid_agg_rx->buf_size;

        for (; j != (index - 1) % tid_agg_rx->buf_size;
             j = (j + 1) % tid_agg_rx->buf_size) {
            if (tid_agg_rx->reorder_buf[j])
                break;
        }

 set_release_timer:

        mod_timer(&tid_agg_rx->reorder_timer,
              tid_agg_rx->reorder_time[j] + 1 +
              HT_RX_REORDER_BUF_TIMEOUT);
    } else {
        del_timer(&tid_agg_rx->reorder_timer);
    }
}

/*
 * As this function belongs to the RX path it must be under
 * rcu_read_lock protection. It returns false if the frame
 * can be processed immediately, true if it was consumed.
 */
static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_sub_if_data *sdata,
                         struct tid_ampdu_rx *tid_agg_rx,
                         struct sk_buff *skb)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
    u16 sc = le16_to_cpu(hdr->seq_ctrl);
    u16 mpdu_seq_num = (sc & IEEE80211_SCTL_SEQ) >> 4;
    u16 head_seq_num, buf_size;
    int index;
    bool ret = true;

    spin_lock(&tid_agg_rx->reorder_lock);

    buf_size = tid_agg_rx->buf_size;
    head_seq_num = tid_agg_rx->head_seq_num;

    /* frame with out of date sequence number */
    if (seq_less(mpdu_seq_num, head_seq_num)) {
        dev_kfree_skb(skb);
        goto out;
    }

    /*
     * If frame the sequence number exceeds our buffering window
     * size release some previous frames to make room for this one.
     */
    if (!seq_less(mpdu_seq_num, head_seq_num + buf_size)) {
        head_seq_num = seq_inc(seq_sub(mpdu_seq_num, buf_size));
        /* release stored frames up to new head to stack */
        ieee80211_release_reorder_frames(sdata, tid_agg_rx,
                         head_seq_num);
    }

    /* Now the new frame is always in the range of the reordering buffer */

    index = seq_sub(mpdu_seq_num, tid_agg_rx->ssn) % tid_agg_rx->buf_size;

    /* check if we already stored this frame */
    if (tid_agg_rx->reorder_buf[index]) {
        dev_kfree_skb(skb);
        goto out;
    }

    /*
     * If the current MPDU is in the right order and nothing else
     * is stored we can process it directly, no need to buffer it.
     * If it is first but there's something stored, we may be able
     * to release frames after this one.
     */
    if (mpdu_seq_num == tid_agg_rx->head_seq_num &&
        tid_agg_rx->stored_mpdu_num == 0) {
        tid_agg_rx->head_seq_num = seq_inc(tid_agg_rx->head_seq_num);
        ret = false;
        goto out;
    }

    /* put the frame in the reordering buffer */
    tid_agg_rx->reorder_buf[index] = skb;
    tid_agg_rx->reorder_time[index] = jiffies;
    tid_agg_rx->stored_mpdu_num++;
    ieee80211_sta_reorder_release(sdata, tid_agg_rx);

 out:
    spin_unlock(&tid_agg_rx->reorder_lock);
    return ret;
}

/*
 * Reorder MPDUs from A-MPDUs, keeping them on a buffer. Returns
 * true if the MPDU was buffered, false if it should be processed.
 */
static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx)
{
    struct sk_buff *skb = rx->skb;
    struct ieee80211_local *local = rx->local;
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct sta_info *sta = rx->sta;
    struct tid_ampdu_rx *tid_agg_rx;
    u16 sc;
    u8 tid, ack_policy;

    if (!ieee80211_is_data_qos(hdr->frame_control))
        goto dont_reorder;

    /*
     * filter the QoS data rx stream according to
     * STA/TID and check if this STA/TID is on aggregation
     */

    if (!sta)
        goto dont_reorder;

    ack_policy = *ieee80211_get_qos_ctl(hdr) &
             IEEE80211_QOS_CTL_ACK_POLICY_MASK;
    tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;

    tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
    if (!tid_agg_rx)
        goto dont_reorder;

    /* qos null data frames are excluded */
    if (unlikely(hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_NULLFUNC)))
        goto dont_reorder;

    /* not part of a BA session */
    if (ack_policy != IEEE80211_QOS_CTL_ACK_POLICY_BLOCKACK &&
        ack_policy != IEEE80211_QOS_CTL_ACK_POLICY_NORMAL)
        goto dont_reorder;

    /* not actually part of this BA session */
    if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
        goto dont_reorder;

    /* new, potentially un-ordered, ampdu frame - process it */

    /* reset session timer */
    if (tid_agg_rx->timeout)
        tid_agg_rx->last_rx = jiffies;

    /* if this mpdu is fragmented - terminate rx aggregation session */
    sc = le16_to_cpu(hdr->seq_ctrl);
    if (sc & IEEE80211_SCTL_FRAG) {
        skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
        skb_queue_tail(&rx->sdata->skb_queue, skb);
        ieee80211_queue_work(&local->hw, &rx->sdata->work);
        return;
    }

    /*
     * No locking needed -- we will only ever process one
     * RX packet at a time, and thus own tid_agg_rx. All
     * other code manipulating it needs to (and does) make
     * sure that we cannot get to it any more before doing
     * anything with it.
     */
    if (ieee80211_sta_manage_reorder_buf(rx->sdata, tid_agg_rx, skb))
        return;

 dont_reorder:
    skb_queue_tail(&local->rx_skb_queue, skb);
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_check(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

    /* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */
    if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) {
        if (unlikely(ieee80211_has_retry(hdr->frame_control) &&
                 rx->sta->last_seq_ctrl[rx->seqno_idx] ==
                 hdr->seq_ctrl)) {
            if (status->rx_flags & IEEE80211_RX_RA_MATCH) {
                rx->local->dot11FrameDuplicateCount++;
                rx->sta->num_duplicates++;
            }
            return RX_DROP_UNUSABLE;
        } else
            rx->sta->last_seq_ctrl[rx->seqno_idx] = hdr->seq_ctrl;
    }

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

    /* Drop disallowed frame classes based on STA auth/assoc state;
     * IEEE 802.11, Chap 5.5.
     *
     * mac80211 filters 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 (ieee80211_vif_is_mesh(&rx->sdata->vif))
        return ieee80211_rx_mesh_check(rx);

    if (unlikely((ieee80211_is_data(hdr->frame_control) ||
              ieee80211_is_pspoll(hdr->frame_control)) &&
             rx->sdata->vif.type != NL80211_IFTYPE_ADHOC &&
             rx->sdata->vif.type != NL80211_IFTYPE_WDS &&
             (!rx->sta || !test_sta_flag(rx->sta, WLAN_STA_ASSOC)))) {
        /*
         * accept port control frames from the AP even when it's not
         * yet marked ASSOC to prevent a race where we don't set the
         * assoc bit quickly enough before it sends the first frame
         */
        if (rx->sta && rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
            ieee80211_is_data_present(hdr->frame_control)) {
            unsigned int hdrlen;
            __be16 ethertype;

            hdrlen = ieee80211_hdrlen(hdr->frame_control);

            if (rx->skb->len < hdrlen + 8)
                return RX_DROP_MONITOR;

            skb_copy_bits(rx->skb, hdrlen + 6, &ethertype, 2);
            if (ethertype == rx->sdata->control_port_protocol)
                return RX_CONTINUE;
        }

        if (rx->sdata->vif.type == NL80211_IFTYPE_AP &&
            cfg80211_rx_spurious_frame(rx->sdata->dev,
                           hdr->addr2,
                           GFP_ATOMIC))
            return RX_DROP_UNUSABLE;

        return RX_DROP_MONITOR;
    }

    return RX_CONTINUE;
}


static ieee80211_rx_result debug_noinline
ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
{
    struct sk_buff *skb = rx->skb;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
    int keyidx;
    int hdrlen;
    ieee80211_rx_result result = RX_DROP_UNUSABLE;
    struct ieee80211_key *sta_ptk = NULL;
    int mmie_keyidx = -1;
    __le16 fc;

    /*
     * Key selection 101
     *
     * There are four types of keys:
     *  - GTK (group keys)
     *  - IGTK (group keys for management frames)
     *  - 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 and IGTKs.
     * Unless, of course, actual WEP keys ("pre-RSNA") are used, then
     * unicast frames can also use key indices 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.
     */

    /*
     * No point in finding a key and decrypting if the frame is neither
     * addressed to us nor a multicast frame.
     */
    if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_CONTINUE;

    /* start without a key */
    rx->key = NULL;

    if (rx->sta)
        sta_ptk = rcu_dereference(rx->sta->ptk);

    fc = hdr->frame_control;

    if (!ieee80211_has_protected(fc))
        mmie_keyidx = ieee80211_get_mmie_keyidx(rx->skb);

    if (!is_multicast_ether_addr(hdr->addr1) && sta_ptk) {
        rx->key = sta_ptk;
        if ((status->flag & RX_FLAG_DECRYPTED) &&
            (status->flag & RX_FLAG_IV_STRIPPED))
            return RX_CONTINUE;
        /* Skip decryption if the frame is not protected. */
        if (!ieee80211_has_protected(fc))
            return RX_CONTINUE;
    } else if (mmie_keyidx >= 0) {
        /* Broadcast/multicast robust management frame / BIP */
        if ((status->flag & RX_FLAG_DECRYPTED) &&
            (status->flag & RX_FLAG_IV_STRIPPED))
            return RX_CONTINUE;

        if (mmie_keyidx < NUM_DEFAULT_KEYS ||
            mmie_keyidx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
            return RX_DROP_MONITOR; /* unexpected BIP keyidx */
        if (rx->sta)
            rx->key = rcu_dereference(rx->sta->gtk[mmie_keyidx]);
        if (!rx->key)
            rx->key = rcu_dereference(rx->sdata->keys[mmie_keyidx]);
    } else if (!ieee80211_has_protected(fc)) {
        /*
         * The frame was not protected, so skip decryption. However, we
         * need to set rx->key if there is a key that could have been
         * used so that the frame may be dropped if encryption would
         * have been expected.
         */
        struct ieee80211_key *key = NULL;
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        int i;

        if (ieee80211_is_mgmt(fc) &&
            is_multicast_ether_addr(hdr->addr1) &&
            (key = rcu_dereference(rx->sdata->default_mgmt_key)))
            rx->key = key;
        else {
            if (rx->sta) {
                for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
                    key = rcu_dereference(rx->sta->gtk[i]);
                    if (key)
                        break;
                }
            }
            if (!key) {
                for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
                    key = rcu_dereference(sdata->keys[i]);
                    if (key)
                        break;
                }
            }
            if (key)
                rx->key = key;
        }
        return RX_CONTINUE;
    } else {
        u8 keyid;
        /*
         * 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 ((status->flag & RX_FLAG_DECRYPTED) &&
            (status->flag & RX_FLAG_IV_STRIPPED))
            return RX_CONTINUE;

        hdrlen = ieee80211_hdrlen(fc);

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

        /*
         * no need to call ieee80211_wep_get_keyidx,
         * it verifies a bunch of things we've done already
         */
        skb_copy_bits(rx->skb, hdrlen + 3, &keyid, 1);
        keyidx = keyid >> 6;

        /* check per-station GTK first, if multicast packet */
        if (is_multicast_ether_addr(hdr->addr1) && rx->sta)
            rx->key = rcu_dereference(rx->sta->gtk[keyidx]);

        /* if not found, try default key */
        if (!rx->key) {
            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.cipher != WLAN_CIPHER_SUITE_WEP40 &&
                rx->key->conf.cipher != WLAN_CIPHER_SUITE_WEP104 &&
                !is_multicast_ether_addr(hdr->addr1))
                rx->key = NULL;
        }
    }

    if (rx->key) {
        if (unlikely(rx->key->flags & KEY_FLAG_TAINTED))
            return RX_DROP_MONITOR;

        rx->key->tx_rx_count++;
        /* TODO: add threshold stuff again */
    } else {
        return RX_DROP_MONITOR;
    }

    switch (rx->key->conf.cipher) {
    case WLAN_CIPHER_SUITE_WEP40:
    case WLAN_CIPHER_SUITE_WEP104:
        result = ieee80211_crypto_wep_decrypt(rx);
        break;
    case WLAN_CIPHER_SUITE_TKIP:
        result = ieee80211_crypto_tkip_decrypt(rx);
        break;
    case WLAN_CIPHER_SUITE_CCMP:
        result = ieee80211_crypto_ccmp_decrypt(rx);
        break;
    case WLAN_CIPHER_SUITE_AES_CMAC:
        result = ieee80211_crypto_aes_cmac_decrypt(rx);
        break;
    default:
        /*
         * We can reach here only with HW-only algorithms
         * but why didn't it decrypt the frame?!
         */
        return RX_DROP_UNUSABLE;
    }

    /* the hdr variable is invalid after the decrypt handlers */

    /* either the frame has been decrypted or will be dropped */
    status->flag |= RX_FLAG_DECRYPTED;

    return result;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_check_more_data(struct ieee80211_rx_data *rx)
{
    struct ieee80211_local *local;
    struct ieee80211_hdr *hdr;
    struct sk_buff *skb;

    local = rx->local;
    skb = rx->skb;
    hdr = (struct ieee80211_hdr *) skb->data;

    if (!local->pspolling)
        return RX_CONTINUE;

    if (!ieee80211_has_fromds(hdr->frame_control))
        /* this is not from AP */
        return RX_CONTINUE;

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

    if (!ieee80211_has_moredata(hdr->frame_control)) {
        /* AP has no more frames buffered for us */
        local->pspolling = false;
        return RX_CONTINUE;
    }

    /* more data bit is set, let's request a new frame from the AP */
    ieee80211_send_pspoll(local, rx->sdata);

    return RX_CONTINUE;
}

static void ap_sta_ps_start(struct sta_info *sta)
{
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    struct ieee80211_local *local = sdata->local;

    atomic_inc(&sdata->bss->num_sta_ps);
    set_sta_flag(sta, WLAN_STA_PS_STA);
    if (!(local->hw.flags & IEEE80211_HW_AP_LINK_PS))
        drv_sta_notify(local, sdata, STA_NOTIFY_SLEEP, &sta->sta);
    ps_dbg(sdata, "STA %pM aid %d enters power save mode\n",
           sta->sta.addr, sta->sta.aid);
}

static void ap_sta_ps_end(struct sta_info *sta)
{
    ps_dbg(sta->sdata, "STA %pM aid %d exits power save mode\n",
           sta->sta.addr, sta->sta.aid);

    if (test_sta_flag(sta, WLAN_STA_PS_DRIVER)) {
        ps_dbg(sta->sdata, "STA %pM aid %d driver-ps-blocked\n",
               sta->sta.addr, sta->sta.aid);
        return;
    }

    ieee80211_sta_ps_deliver_wakeup(sta);
}

int ieee80211_sta_ps_transition(struct ieee80211_sta *sta, bool start)
{
    struct sta_info *sta_inf = container_of(sta, struct sta_info, sta);
    bool in_ps;

    WARN_ON(!(sta_inf->local->hw.flags & IEEE80211_HW_AP_LINK_PS));

    /* Don't let the same PS state be set twice */
    in_ps = test_sta_flag(sta_inf, WLAN_STA_PS_STA);
    if ((start && in_ps) || (!start && !in_ps))
        return -EINVAL;

    if (start)
        ap_sta_ps_start(sta_inf);
    else
        ap_sta_ps_end(sta_inf);

    return 0;
}
EXPORT_SYMBOL(ieee80211_sta_ps_transition);

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_uapsd_and_pspoll(struct ieee80211_rx_data *rx)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_hdr *hdr = (void *)rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
    int tid, ac;

    if (!rx->sta || !(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_CONTINUE;

    if (sdata->vif.type != NL80211_IFTYPE_AP &&
        sdata->vif.type != NL80211_IFTYPE_AP_VLAN)
        return RX_CONTINUE;

    /*
     * The device handles station powersave, so don't do anything about
     * uAPSD and PS-Poll frames (the latter shouldn't even come up from
     * it to mac80211 since they're handled.)
     */
    if (sdata->local->hw.flags & IEEE80211_HW_AP_LINK_PS)
        return RX_CONTINUE;

    /*
     * Don't do anything if the station isn't already asleep. In
     * the uAPSD case, the station will probably be marked asleep,
     * in the PS-Poll case the station must be confused ...
     */
    if (!test_sta_flag(rx->sta, WLAN_STA_PS_STA))
        return RX_CONTINUE;

    if (unlikely(ieee80211_is_pspoll(hdr->frame_control))) {
        if (!test_sta_flag(rx->sta, WLAN_STA_SP)) {
            if (!test_sta_flag(rx->sta, WLAN_STA_PS_DRIVER))
                ieee80211_sta_ps_deliver_poll_response(rx->sta);
            else
                set_sta_flag(rx->sta, WLAN_STA_PSPOLL);
        }

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

        return RX_QUEUED;
    } else if (!ieee80211_has_morefrags(hdr->frame_control) &&
           !(status->rx_flags & IEEE80211_RX_DEFERRED_RELEASE) &&
           ieee80211_has_pm(hdr->frame_control) &&
           (ieee80211_is_data_qos(hdr->frame_control) ||
            ieee80211_is_qos_nullfunc(hdr->frame_control))) {
        tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
        ac = ieee802_1d_to_ac[tid & 7];

        /*
         * If this AC is not trigger-enabled do nothing.
         *
         * NB: This could/should check a separate bitmap of trigger-
         * enabled queues, but for now we only implement uAPSD w/o
         * TSPEC changes to the ACs, so they're always the same.
         */
        if (!(rx->sta->sta.uapsd_queues & BIT(ac)))
            return RX_CONTINUE;

        /* if we are in a service period, do nothing */
        if (test_sta_flag(rx->sta, WLAN_STA_SP))
            return RX_CONTINUE;

        if (!test_sta_flag(rx->sta, WLAN_STA_PS_DRIVER))
            ieee80211_sta_ps_deliver_uapsd(rx->sta);
        else
            set_sta_flag(rx->sta, WLAN_STA_UAPSD);
    }

    return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
{
    struct sta_info *sta = rx->sta;
    struct sk_buff *skb = rx->skb;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

    if (!sta)
        return RX_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 start using different BSSID.
     */
    if (rx->sdata->vif.type == NL80211_IFTYPE_ADHOC) {
        u8 *bssid = ieee80211_get_bssid(hdr, rx->skb->len,
                        NL80211_IFTYPE_ADHOC);
        if (ether_addr_equal(bssid, rx->sdata->u.ibss.bssid)) {
            sta->last_rx = jiffies;
            if (ieee80211_is_data(hdr->frame_control)) {
                sta->last_rx_rate_idx = status->rate_idx;
                sta->last_rx_rate_flag = status->flag;
            }
        }
    } else if (!is_multicast_ether_addr(hdr->addr1)) {
        /*
         * Mesh beacons will update last_rx when if they are found to
         * match the current local configuration when processed.
         */
        sta->last_rx = jiffies;
        if (ieee80211_is_data(hdr->frame_control)) {
            sta->last_rx_rate_idx = status->rate_idx;
            sta->last_rx_rate_flag = status->flag;
        }
    }

    if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_CONTINUE;

    if (rx->sdata->vif.type == NL80211_IFTYPE_STATION)
        ieee80211_sta_rx_notify(rx->sdata, hdr);

    sta->rx_fragments++;
    sta->rx_bytes += rx->skb->len;
    if (!(status->flag & RX_FLAG_NO_SIGNAL_VAL)) {
        sta->last_signal = status->signal;
        ewma_add(&sta->avg_signal, -status->signal);
    }

    /*
     * Change STA power saving mode only at the end of a frame
     * exchange sequence.
     */
    if (!(sta->local->hw.flags & IEEE80211_HW_AP_LINK_PS) &&
        !ieee80211_has_morefrags(hdr->frame_control) &&
        !(status->rx_flags & IEEE80211_RX_DEFERRED_RELEASE) &&
        (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
         rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)) {
        if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
            /*
             * Ignore doze->wake transitions that are
             * indicated by non-data frames, the standard
             * is unclear here, but for example going to
             * PS mode and then scanning would cause a
             * doze->wake transition for the probe request,
             * and that is clearly undesirable.
             */
            if (ieee80211_is_data(hdr->frame_control) &&
                !ieee80211_has_pm(hdr->frame_control))
                ap_sta_ps_end(sta);
        } else {
            if (ieee80211_has_pm(hdr->frame_control))
                ap_sta_ps_start(sta);
        }
    }

    /*
     * Drop (qos-)data::nullfunc frames silently, since they
     * are used only to control station power saving mode.
     */
    if (ieee80211_is_nullfunc(hdr->frame_control) ||
        ieee80211_is_qos_nullfunc(hdr->frame_control)) {
        I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);

        /*
         * If we receive a 4-addr nullfunc frame from a STA
         * that was not moved to a 4-addr STA vlan yet send
         * the event to userspace and for older hostapd drop
         * the frame to the monitor interface.
         */
        if (ieee80211_has_a4(hdr->frame_control) &&
            (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
             (rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
              !rx->sdata->u.vlan.sta))) {
            if (!test_and_set_sta_flag(sta, WLAN_STA_4ADDR_EVENT))
                cfg80211_rx_unexpected_4addr_frame(
                    rx->sdata->dev, sta->sta.addr,
                    GFP_ATOMIC);
            return RX_DROP_MONITOR;
        }
        /*
         * Update counter and free packet here to avoid
         * counting this as a dropped packed.
         */
        sta->rx_packets++;
        dev_kfree_skb(rx->skb);
        return RX_QUEUED;
    }

    return RX_CONTINUE;
} /* ieee80211_rx_h_sta_process */

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))
        __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,
              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;

        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;

        /*
         * Check ftype and addresses are equal, else check next fragment
         */
        if (((hdr->frame_control ^ f_hdr->frame_control) &
             cpu_to_le16(IEEE80211_FCTL_FTYPE)) ||
            !ether_addr_equal(hdr->addr1, f_hdr->addr1) ||
            !ether_addr_equal(hdr->addr2, f_hdr->addr2))
            continue;

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

    return NULL;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *hdr;
    u16 sc;
    __le16 fc;
    unsigned int frag, seq;
    struct ieee80211_fragment_entry *entry;
    struct sk_buff *skb;
    struct ieee80211_rx_status *status;

    hdr = (struct ieee80211_hdr *)rx->skb->data;
    fc = hdr->frame_control;

    if (ieee80211_is_ctl(fc))
        return RX_CONTINUE;

    sc = le16_to_cpu(hdr->seq_ctrl);
    frag = sc & IEEE80211_SCTL_FRAG;

    if (likely((!ieee80211_has_morefrags(fc) && frag == 0) ||
           is_multicast_ether_addr(hdr->addr1))) {
        /* not fragmented */
        goto out;
    }
    I802_DEBUG_INC(rx->local->rx_handlers_fragments);

    if (skb_linearize(rx->skb))
        return RX_DROP_UNUSABLE;

    /*
     *  skb_linearize() might change the skb->data and
     *  previously cached variables (in this case, hdr) need to
     *  be refreshed with the new data.
     */
    hdr = (struct ieee80211_hdr *)rx->skb->data;
    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->seqno_idx, &(rx->skb));
        if (rx->key && rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP &&
            ieee80211_has_protected(fc)) {
            int queue = rx->security_idx;
            /* 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[queue],
                   CCMP_PN_LEN);
        }
        return RX_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, frag, seq,
                      rx->seqno_idx, hdr);
    if (!entry) {
        I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
        return RX_DROP_MONITOR;
    }

    /* 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;
        int queue;
        if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP)
            return RX_DROP_UNUSABLE;
        memcpy(pn, entry->last_pn, CCMP_PN_LEN);
        for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
            pn[i]++;
            if (pn[i])
                break;
        }
        queue = rx->security_idx;
        rpn = rx->key->u.ccmp.rx_pn[queue];
        if (memcmp(pn, rpn, CCMP_PN_LEN))
            return RX_DROP_UNUSABLE;
        memcpy(entry->last_pn, pn, CCMP_PN_LEN);
    }

    skb_pull(rx->skb, ieee80211_hdrlen(fc));
    __skb_queue_tail(&entry->skb_list, rx->skb);
    entry->last_frag = frag;
    entry->extra_len += rx->skb->len;
    if (ieee80211_has_morefrags(fc)) {
        rx->skb = NULL;
        return RX_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 RX_DROP_UNUSABLE;
        }
    }
    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 */
    status = IEEE80211_SKB_RXCB(rx->skb);
    status->rx_flags |= IEEE80211_RX_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 RX_CONTINUE;
}

static int
ieee80211_802_1x_port_control(struct ieee80211_rx_data *rx)
{
    if (unlikely(!rx->sta ||
        !test_sta_flag(rx->sta, WLAN_STA_AUTHORIZED)))
        return -EACCES;

    return 0;
}

static int
ieee80211_drop_unencrypted(struct ieee80211_rx_data *rx, __le16 fc)
{
    struct sk_buff *skb = rx->skb;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

    /*
     * Pass through unencrypted frames if the hardware has
     * decrypted them already.
     */
    if (status->flag & RX_FLAG_DECRYPTED)
        return 0;

    /* Drop unencrypted frames if key is set. */
    if (unlikely(!ieee80211_has_protected(fc) &&
             !ieee80211_is_nullfunc(fc) &&
             ieee80211_is_data(fc) &&
             (rx->key || rx->sdata->drop_unencrypted)))
        return -EACCES;

    return 0;
}

static int
ieee80211_drop_unencrypted_mgmt(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
    __le16 fc = hdr->frame_control;

    /*
     * Pass through unencrypted frames if the hardware has
     * decrypted them already.
     */
    if (status->flag & RX_FLAG_DECRYPTED)
        return 0;

    if (rx->sta && test_sta_flag(rx->sta, WLAN_STA_MFP)) {
        if (unlikely(!ieee80211_has_protected(fc) &&
                 ieee80211_is_unicast_robust_mgmt_frame(rx->skb) &&
                 rx->key)) {
            if (ieee80211_is_deauth(fc))
                cfg80211_send_unprot_deauth(rx->sdata->dev,
                                rx->skb->data,
                                rx->skb->len);
            else if (ieee80211_is_disassoc(fc))
                cfg80211_send_unprot_disassoc(rx->sdata->dev,
                                  rx->skb->data,
                                  rx->skb->len);
            return -EACCES;
        }
        /* BIP does not use Protected field, so need to check MMIE */
        if (unlikely(ieee80211_is_multicast_robust_mgmt_frame(rx->skb) &&
                 ieee80211_get_mmie_keyidx(rx->skb) < 0)) {
            if (ieee80211_is_deauth(fc))
                cfg80211_send_unprot_deauth(rx->sdata->dev,
                                rx->skb->data,
                                rx->skb->len);
            else if (ieee80211_is_disassoc(fc))
                cfg80211_send_unprot_disassoc(rx->sdata->dev,
                                  rx->skb->data,
                                  rx->skb->len);
            return -EACCES;
        }
        /*
         * When using MFP, Action frames are not allowed prior to
         * having configured keys.
         */
        if (unlikely(ieee80211_is_action(fc) && !rx->key &&
                 ieee80211_is_robust_mgmt_frame(
                     (struct ieee80211_hdr *) rx->skb->data)))
            return -EACCES;
    }

    return 0;
}

static int
__ieee80211_data_to_8023(struct ieee80211_rx_data *rx, bool *port_control)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    bool check_port_control = false;
    struct ethhdr *ehdr;
    int ret;

    *port_control = false;
    if (ieee80211_has_a4(hdr->frame_control) &&
        sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->u.vlan.sta)
        return -1;

    if (sdata->vif.type == NL80211_IFTYPE_STATION &&
        !!sdata->u.mgd.use_4addr != !!ieee80211_has_a4(hdr->frame_control)) {

        if (!sdata->u.mgd.use_4addr)
            return -1;
        else
            check_port_control = true;
    }

    if (is_multicast_ether_addr(hdr->addr1) &&
        sdata->vif.type == NL80211_IFTYPE_AP_VLAN && sdata->u.vlan.sta)
        return -1;

    ret = ieee80211_data_to_8023(rx->skb, sdata->vif.addr, sdata->vif.type);
    if (ret < 0)
        return ret;

    ehdr = (struct ethhdr *) rx->skb->data;
    if (ehdr->h_proto == rx->sdata->control_port_protocol)
        *port_control = true;
    else if (check_port_control)
        return -1;

    return 0;
}

/*
 * requires that rx->skb is a frame with ethernet header
 */
static bool ieee80211_frame_allowed(struct ieee80211_rx_data *rx, __le16 fc)
{
    static const u8 pae_group_addr[ETH_ALEN] __aligned(2)
        = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x03 };
    struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;

    /*
     * Allow EAPOL frames to us/the PAE group address regardless
     * of whether the frame was encrypted or not.
     */
    if (ehdr->h_proto == rx->sdata->control_port_protocol &&
        (ether_addr_equal(ehdr->h_dest, rx->sdata->vif.addr) ||
         ether_addr_equal(ehdr->h_dest, pae_group_addr)))
        return true;

    if (ieee80211_802_1x_port_control(rx) ||
        ieee80211_drop_unencrypted(rx, fc))
        return false;

    return true;
}

/*
 * requires that rx->skb is a frame with ethernet header
 */
static void
ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct net_device *dev = sdata->dev;
    struct sk_buff *skb, *xmit_skb;
    struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;
    struct sta_info *dsta;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

    skb = rx->skb;
    xmit_skb = NULL;

    if ((sdata->vif.type == NL80211_IFTYPE_AP ||
         sdata->vif.type == NL80211_IFTYPE_AP_VLAN) &&
        !(sdata->flags & IEEE80211_SDATA_DONT_BRIDGE_PACKETS) &&
        (status->rx_flags & IEEE80211_RX_RA_MATCH) &&
        (sdata->vif.type != NL80211_IFTYPE_AP_VLAN || !sdata->u.vlan.sta)) {
        if (is_multicast_ether_addr(ehdr->h_dest)) {
            /*
             * send multicast frames both to higher layers in
             * local net stack and back to the wireless medium
             */
            xmit_skb = skb_copy(skb, GFP_ATOMIC);
            if (!xmit_skb)
                net_info_ratelimited("%s: failed to clone multicast frame\n",
                            dev->name);
        } else {
            dsta = sta_info_get(sdata, skb->data);
            if (dsta) {
                /*
                 * The destination station is associated to
                 * this AP (in this VLAN), so send the frame
                 * directly to it and do not pass it to local
                 * net stack.
                 */
                xmit_skb = skb;
                skb = NULL;
            }
        }
    }

    if (skb) {
        int align __maybe_unused;

#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
        /*
         * 'align' will only take the values 0 or 2 here
         * since all frames are required to be aligned
         * to 2-byte boundaries when being passed to
         * mac80211. That also explains the __skb_push()
         * below.
         */
        align = ((unsigned long)(skb->data + sizeof(struct ethhdr))) & 3;
        if (align) {
            if (WARN_ON(skb_headroom(skb) < 3)) {
                dev_kfree_skb(skb);
                skb = NULL;
            } else {
                u8 *data = skb->data;
                size_t len = skb_headlen(skb);
                skb->data -= align;
                memmove(skb->data, data, len);
                skb_set_tail_pointer(skb, len);
            }
        }
#endif

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

    if (xmit_skb) {
        /*
         * Send to wireless media and increase priority by 256 to
         * keep the received priority instead of reclassifying
         * the frame (see cfg80211_classify8021d).
         */
        xmit_skb->priority += 256;
        xmit_skb->protocol = htons(ETH_P_802_3);
        skb_reset_network_header(xmit_skb);
        skb_reset_mac_header(xmit_skb);
        dev_queue_xmit(xmit_skb);
    }
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
{
    struct net_device *dev = rx->sdata->dev;
    struct sk_buff *skb = rx->skb;
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
    __le16 fc = hdr->frame_control;
    struct sk_buff_head frame_list;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

    if (unlikely(!ieee80211_is_data(fc)))
        return RX_CONTINUE;

    if (unlikely(!ieee80211_is_data_present(fc)))
        return RX_DROP_MONITOR;

    if (!(status->rx_flags & IEEE80211_RX_AMSDU))
        return RX_CONTINUE;

    if (ieee80211_has_a4(hdr->frame_control) &&
        rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
        !rx->sdata->u.vlan.sta)
        return RX_DROP_UNUSABLE;

    if (is_multicast_ether_addr(hdr->addr1) &&
        ((rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
          rx->sdata->u.vlan.sta) ||
         (rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
          rx->sdata->u.mgd.use_4addr)))
        return RX_DROP_UNUSABLE;

    skb->dev = dev;
    __skb_queue_head_init(&frame_list);

    if (skb_linearize(skb))
        return RX_DROP_UNUSABLE;

    ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr,
                 rx->sdata->vif.type,
                 rx->local->hw.extra_tx_headroom, true);

    while (!skb_queue_empty(&frame_list)) {
        rx->skb = __skb_dequeue(&frame_list);

        if (!ieee80211_frame_allowed(rx, fc)) {
            dev_kfree_skb(rx->skb);
            continue;
        }
        dev->stats.rx_packets++;
        dev->stats.rx_bytes += rx->skb->len;

        ieee80211_deliver_skb(rx);
    }

    return RX_QUEUED;
}

#ifdef CONFIG_MAC80211_MESH
static ieee80211_rx_result
ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
{
    struct ieee80211_hdr *fwd_hdr, *hdr;
    struct ieee80211_tx_info *info;
    struct ieee80211s_hdr *mesh_hdr;
    struct sk_buff *skb = rx->skb, *fwd_skb;
    struct ieee80211_local *local = rx->local;
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
    __le16 reason = cpu_to_le16(WLAN_REASON_MESH_PATH_NOFORWARD);
    u16 q, hdrlen;

    hdr = (struct ieee80211_hdr *) skb->data;
    hdrlen = ieee80211_hdrlen(hdr->frame_control);

    /* make sure fixed part of mesh header is there, also checks skb len */
    if (!pskb_may_pull(rx->skb, hdrlen + 6))
        return RX_DROP_MONITOR;

    mesh_hdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);

    /* make sure full mesh header is there, also checks skb len */
    if (!pskb_may_pull(rx->skb,
               hdrlen + ieee80211_get_mesh_hdrlen(mesh_hdr)))
        return RX_DROP_MONITOR;

    /* reload pointers */
    hdr = (struct ieee80211_hdr *) skb->data;
    mesh_hdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);

    /* frame is in RMC, don't forward */
    if (ieee80211_is_data(hdr->frame_control) &&
        is_multicast_ether_addr(hdr->addr1) &&
        mesh_rmc_check(hdr->addr3, mesh_hdr, rx->sdata))
        return RX_DROP_MONITOR;

    if (!ieee80211_is_data(hdr->frame_control) ||
        !(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_CONTINUE;

    if (!mesh_hdr->ttl)
        return RX_DROP_MONITOR;

    if (mesh_hdr->flags & MESH_FLAGS_AE) {
        struct mesh_path *mppath;
        char *proxied_addr;
        char *mpp_addr;

        if (is_multicast_ether_addr(hdr->addr1)) {
            mpp_addr = hdr->addr3;
            proxied_addr = mesh_hdr->eaddr1;
        } else if (mesh_hdr->flags & MESH_FLAGS_AE_A5_A6) {
            /* has_a4 already checked in ieee80211_rx_mesh_check */
            mpp_addr = hdr->addr4;
            proxied_addr = mesh_hdr->eaddr2;
        } else {
            return RX_DROP_MONITOR;
        }

        rcu_read_lock();
        mppath = mpp_path_lookup(proxied_addr, sdata);
        if (!mppath) {
            mpp_path_add(proxied_addr, mpp_addr, sdata);
        } else {
            spin_lock_bh(&mppath->state_lock);
            if (!ether_addr_equal(mppath->mpp, mpp_addr))
                memcpy(mppath->mpp, mpp_addr, ETH_ALEN);
            spin_unlock_bh(&mppath->state_lock);
        }
        rcu_read_unlock();
    }

    /* Frame has reached destination.  Don't forward */
    if (!is_multicast_ether_addr(hdr->addr1) &&
        ether_addr_equal(sdata->vif.addr, hdr->addr3))
        return RX_CONTINUE;

    q = ieee80211_select_queue_80211(sdata, skb, hdr);
    if (ieee80211_queue_stopped(&local->hw, q)) {
        IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, dropped_frames_congestion);
        return RX_DROP_MONITOR;
    }
    skb_set_queue_mapping(skb, q);

    if (!--mesh_hdr->ttl) {
        IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, dropped_frames_ttl);
        goto out;
    }

    if (!ifmsh->mshcfg.dot11MeshForwarding)
        goto out;

    fwd_skb = skb_copy(skb, GFP_ATOMIC);
    if (!fwd_skb) {
        net_info_ratelimited("%s: failed to clone mesh frame\n",
                    sdata->name);
        goto out;
    }

    fwd_hdr =  (struct ieee80211_hdr *) fwd_skb->data;
    info = IEEE80211_SKB_CB(fwd_skb);
    memset(info, 0, sizeof(*info));
    info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
    info->control.vif = &rx->sdata->vif;
    info->control.jiffies = jiffies;
    if (is_multicast_ether_addr(fwd_hdr->addr1)) {
        IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, fwded_mcast);
        memcpy(fwd_hdr->addr2, sdata->vif.addr, ETH_ALEN);
    } else if (!mesh_nexthop_lookup(fwd_skb, sdata)) {
        IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, fwded_unicast);
    } else {
        /* unable to resolve next hop */
        mesh_path_error_tx(ifmsh->mshcfg.element_ttl, fwd_hdr->addr3,
                    0, reason, fwd_hdr->addr2, sdata);
        IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, dropped_frames_no_route);
        kfree_skb(fwd_skb);
        return RX_DROP_MONITOR;
    }

    IEEE80211_IFSTA_MESH_CTR_INC(ifmsh, fwded_frames);
    ieee80211_add_pending_skb(local, fwd_skb);
 out:
    if (is_multicast_ether_addr(hdr->addr1) ||
        sdata->dev->flags & IFF_PROMISC)
        return RX_CONTINUE;
    else
        return RX_DROP_MONITOR;
}
#endif

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_data(struct ieee80211_rx_data *rx)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_local *local = rx->local;
    struct net_device *dev = sdata->dev;
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
    __le16 fc = hdr->frame_control;
    bool port_control;
    int err;

    if (unlikely(!ieee80211_is_data(hdr->frame_control)))
        return RX_CONTINUE;

    if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
        return RX_DROP_MONITOR;

    /*
     * Send unexpected-4addr-frame event to hostapd. For older versions,
     * also drop the frame to cooked monitor interfaces.
     */
    if (ieee80211_has_a4(hdr->frame_control) &&
        sdata->vif.type == NL80211_IFTYPE_AP) {
        if (rx->sta &&
            !test_and_set_sta_flag(rx->sta, WLAN_STA_4ADDR_EVENT))
            cfg80211_rx_unexpected_4addr_frame(
                rx->sdata->dev, rx->sta->sta.addr, GFP_ATOMIC);
        return RX_DROP_MONITOR;
    }

    err = __ieee80211_data_to_8023(rx, &port_control);
    if (unlikely(err))
        return RX_DROP_UNUSABLE;

    if (!ieee80211_frame_allowed(rx, fc))
        return RX_DROP_MONITOR;

    if (rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
        unlikely(port_control) && sdata->bss) {
        sdata = container_of(sdata->bss, struct ieee80211_sub_if_data,
                     u.ap);
        dev = sdata->dev;
        rx->sdata = sdata;
    }

    rx->skb->dev = dev;

    dev->stats.rx_packets++;
    dev->stats.rx_bytes += rx->skb->len;

    if (local->ps_sdata && local->hw.conf.dynamic_ps_timeout > 0 &&
        !is_multicast_ether_addr(
            ((struct ethhdr *)rx->skb->data)->h_dest) &&
        (!local->scanning &&
         !test_bit(SDATA_STATE_OFFCHANNEL, &sdata->state))) {
            mod_timer(&local->dynamic_ps_timer, jiffies +
             msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
    }

    ieee80211_deliver_skb(rx);

    return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx)
{
    struct sk_buff *skb = rx->skb;
    struct ieee80211_bar *bar = (struct ieee80211_bar *)skb->data;
    struct tid_ampdu_rx *tid_agg_rx;
    u16 start_seq_num;
    u16 tid;

    if (likely(!ieee80211_is_ctl(bar->frame_control)))
        return RX_CONTINUE;

    if (ieee80211_is_back_req(bar->frame_control)) {
        struct {
            __le16 control, start_seq_num;
        } __packed bar_data;

        if (!rx->sta)
            return RX_DROP_MONITOR;

        if (skb_copy_bits(skb, offsetof(struct ieee80211_bar, control),
                  &bar_data, sizeof(bar_data)))
            return RX_DROP_MONITOR;

        tid = le16_to_cpu(bar_data.control) >> 12;

        tid_agg_rx = rcu_dereference(rx->sta->ampdu_mlme.tid_rx[tid]);
        if (!tid_agg_rx)
            return RX_DROP_MONITOR;

        start_seq_num = le16_to_cpu(bar_data.start_seq_num) >> 4;

        /* reset session timer */
        if (tid_agg_rx->timeout)
            mod_timer(&tid_agg_rx->session_timer,
                  TU_TO_EXP_TIME(tid_agg_rx->timeout));

        spin_lock(&tid_agg_rx->reorder_lock);
        /* release stored frames up to start of BAR */
        ieee80211_release_reorder_frames(rx->sdata, tid_agg_rx,
                         start_seq_num);
        spin_unlock(&tid_agg_rx->reorder_lock);

        kfree_skb(skb);
        return RX_QUEUED;
    }

    /*
     * After this point, we only want management frames,
     * so we can drop all remaining control frames to
     * cooked monitor interfaces.
     */
    return RX_DROP_MONITOR;
}

static void ieee80211_process_sa_query_req(struct ieee80211_sub_if_data *sdata,
                       struct ieee80211_mgmt *mgmt,
                       size_t len)
{
    struct ieee80211_local *local = sdata->local;
    struct sk_buff *skb;
    struct ieee80211_mgmt *resp;

    if (!ether_addr_equal(mgmt->da, sdata->vif.addr)) {
        /* Not to own unicast address */
        return;
    }

    if (!ether_addr_equal(mgmt->sa, sdata->u.mgd.bssid) ||
        !ether_addr_equal(mgmt->bssid, sdata->u.mgd.bssid)) {
        /* Not from the current AP or not associated yet. */
        return;
    }

    if (len < 24 + 1 + sizeof(resp->u.action.u.sa_query)) {
        /* Too short SA Query request frame */
        return;
    }

    skb = dev_alloc_skb(sizeof(*resp) + local->hw.extra_tx_headroom);
    if (skb == NULL)
        return;

    skb_reserve(skb, local->hw.extra_tx_headroom);
    resp = (struct ieee80211_mgmt *) skb_put(skb, 24);
    memset(resp, 0, 24);
    memcpy(resp->da, mgmt->sa, ETH_ALEN);
    memcpy(resp->sa, sdata->vif.addr, ETH_ALEN);
    memcpy(resp->bssid, sdata->u.mgd.bssid, ETH_ALEN);
    resp->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                      IEEE80211_STYPE_ACTION);
    skb_put(skb, 1 + sizeof(resp->u.action.u.sa_query));
    resp->u.action.category = WLAN_CATEGORY_SA_QUERY;
    resp->u.action.u.sa_query.action = WLAN_ACTION_SA_QUERY_RESPONSE;
    memcpy(resp->u.action.u.sa_query.trans_id,
           mgmt->u.action.u.sa_query.trans_id,
           WLAN_SA_QUERY_TR_ID_LEN);

    ieee80211_tx_skb(sdata, skb);
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_mgmt_check(struct ieee80211_rx_data *rx)
{
    struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

    /*
     * From here on, look only at management frames.
     * Data and control frames are already handled,
     * and unknown (reserved) frames are useless.
     */
    if (rx->skb->len < 24)
        return RX_DROP_MONITOR;

    if (!ieee80211_is_mgmt(mgmt->frame_control))
        return RX_DROP_MONITOR;

    if (rx->sdata->vif.type == NL80211_IFTYPE_AP &&
        ieee80211_is_beacon(mgmt->frame_control) &&
        !(rx->flags & IEEE80211_RX_BEACON_REPORTED)) {
        int sig = 0;

        if (rx->local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
            sig = status->signal;

        cfg80211_report_obss_beacon(rx->local->hw.wiphy,
                        rx->skb->data, rx->skb->len,
                        status->freq, sig, GFP_ATOMIC);
        rx->flags |= IEEE80211_RX_BEACON_REPORTED;
    }

    if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_DROP_MONITOR;

    if (ieee80211_drop_unencrypted_mgmt(rx))
        return RX_DROP_UNUSABLE;

    return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
{
    struct ieee80211_local *local = rx->local;
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
    int len = rx->skb->len;

    if (!ieee80211_is_action(mgmt->frame_control))
        return RX_CONTINUE;

    /* drop too small frames */
    if (len < IEEE80211_MIN_ACTION_SIZE)
        return RX_DROP_UNUSABLE;

    if (!rx->sta && mgmt->u.action.category != WLAN_CATEGORY_PUBLIC)
        return RX_DROP_UNUSABLE;

    if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
        return RX_DROP_UNUSABLE;

    switch (mgmt->u.action.category) {
    case WLAN_CATEGORY_HT:
        /* reject HT action frames from stations not supporting HT */
        if (!rx->sta->sta.ht_cap.ht_supported)
            goto invalid;

        if (sdata->vif.type != NL80211_IFTYPE_STATION &&
            sdata->vif.type != NL80211_IFTYPE_MESH_POINT &&
            sdata->vif.type != NL80211_IFTYPE_AP_VLAN &&
            sdata->vif.type != NL80211_IFTYPE_AP &&
            sdata->vif.type != NL80211_IFTYPE_ADHOC)
            break;

        /* verify action & smps_control are present */
        if (len < IEEE80211_MIN_ACTION_SIZE + 2)
            goto invalid;

        switch (mgmt->u.action.u.ht_smps.action) {
        case WLAN_HT_ACTION_SMPS: {
            struct ieee80211_supported_band *sband;
            u8 smps;

            /* convert to HT capability */
            switch (mgmt->u.action.u.ht_smps.smps_control) {
            case WLAN_HT_SMPS_CONTROL_DISABLED:
                smps = WLAN_HT_CAP_SM_PS_DISABLED;
                break;
            case WLAN_HT_SMPS_CONTROL_STATIC:
                smps = WLAN_HT_CAP_SM_PS_STATIC;
                break;
            case WLAN_HT_SMPS_CONTROL_DYNAMIC:
                smps = WLAN_HT_CAP_SM_PS_DYNAMIC;
                break;
            default:
                goto invalid;
            }
            smps <<= IEEE80211_HT_CAP_SM_PS_SHIFT;

            /* if no change do nothing */
            if ((rx->sta->sta.ht_cap.cap &
                    IEEE80211_HT_CAP_SM_PS) == smps)
                goto handled;

            rx->sta->sta.ht_cap.cap &= ~IEEE80211_HT_CAP_SM_PS;
            rx->sta->sta.ht_cap.cap |= smps;

            sband = rx->local->hw.wiphy->bands[status->band];

            rate_control_rate_update(local, sband, rx->sta,
                         IEEE80211_RC_SMPS_CHANGED);
            goto handled;
        }
        default:
            goto invalid;
        }

        break;
    case WLAN_CATEGORY_BACK:
        if (sdata->vif.type != NL80211_IFTYPE_STATION &&
            sdata->vif.type != NL80211_IFTYPE_MESH_POINT &&
            sdata->vif.type != NL80211_IFTYPE_AP_VLAN &&
            sdata->vif.type != NL80211_IFTYPE_AP &&
            sdata->vif.type != NL80211_IFTYPE_ADHOC)
            break;

        /* verify action_code is present */
        if (len < IEEE80211_MIN_ACTION_SIZE + 1)
            break;

        switch (mgmt->u.action.u.addba_req.action_code) {
        case WLAN_ACTION_ADDBA_REQ:
            if (len < (IEEE80211_MIN_ACTION_SIZE +
                   sizeof(mgmt->u.action.u.addba_req)))
                goto invalid;
            break;
        case WLAN_ACTION_ADDBA_RESP:
            if (len < (IEEE80211_MIN_ACTION_SIZE +
                   sizeof(mgmt->u.action.u.addba_resp)))
                goto invalid;
            break;
        case WLAN_ACTION_DELBA:
            if (len < (IEEE80211_MIN_ACTION_SIZE +
                   sizeof(mgmt->u.action.u.delba)))
                goto invalid;
            break;
        default:
            goto invalid;
        }

        goto queue;
    case WLAN_CATEGORY_SPECTRUM_MGMT:
        if (status->band != IEEE80211_BAND_5GHZ)
            break;

        if (sdata->vif.type != NL80211_IFTYPE_STATION)
            break;

        /* verify action_code is present */
        if (len < IEEE80211_MIN_ACTION_SIZE + 1)
            break;

        switch (mgmt->u.action.u.measurement.action_code) {
        case WLAN_ACTION_SPCT_MSR_REQ:
            if (len < (IEEE80211_MIN_ACTION_SIZE +
                   sizeof(mgmt->u.action.u.measurement)))
                break;
            ieee80211_process_measurement_req(sdata, mgmt, len);
            goto handled;
        case WLAN_ACTION_SPCT_CHL_SWITCH:
            if (len < (IEEE80211_MIN_ACTION_SIZE +
                   sizeof(mgmt->u.action.u.chan_switch)))
                break;

            if (sdata->vif.type != NL80211_IFTYPE_STATION)
                break;

            if (!ether_addr_equal(mgmt->bssid, sdata->u.mgd.bssid))
                break;

            goto queue;
        }
        break;
    case WLAN_CATEGORY_SA_QUERY:
        if (len < (IEEE80211_MIN_ACTION_SIZE +
               sizeof(mgmt->u.action.u.sa_query)))
            break;

        switch (mgmt->u.action.u.sa_query.action) {
        case WLAN_ACTION_SA_QUERY_REQUEST:
            if (sdata->vif.type != NL80211_IFTYPE_STATION)
                break;
            ieee80211_process_sa_query_req(sdata, mgmt, len);
            goto handled;
        }
        break;
    case WLAN_CATEGORY_SELF_PROTECTED:
        if (len < (IEEE80211_MIN_ACTION_SIZE +
               sizeof(mgmt->u.action.u.self_prot.action_code)))
            break;

        switch (mgmt->u.action.u.self_prot.action_code) {
        case WLAN_SP_MESH_PEERING_OPEN:
        case WLAN_SP_MESH_PEERING_CLOSE:
        case WLAN_SP_MESH_PEERING_CONFIRM:
            if (!ieee80211_vif_is_mesh(&sdata->vif))
                goto invalid;
            if (sdata->u.mesh.security != IEEE80211_MESH_SEC_NONE)
                /* userspace handles this frame */
                break;
            goto queue;
        case WLAN_SP_MGK_INFORM:
        case WLAN_SP_MGK_ACK:
            if (!ieee80211_vif_is_mesh(&sdata->vif))
                goto invalid;
            break;
        }
        break;
    case WLAN_CATEGORY_MESH_ACTION:
        if (len < (IEEE80211_MIN_ACTION_SIZE +
               sizeof(mgmt->u.action.u.mesh_action.action_code)))
            break;

        if (!ieee80211_vif_is_mesh(&sdata->vif))
            break;
        if (mesh_action_is_path_sel(mgmt) &&
          (!mesh_path_sel_is_hwmp(sdata)))
            break;
        goto queue;
    }

    return RX_CONTINUE;

 invalid:
    status->rx_flags |= IEEE80211_RX_MALFORMED_ACTION_FRM;
    /* will return in the next handlers */
    return RX_CONTINUE;

 handled:
    if (rx->sta)
        rx->sta->rx_packets++;
    dev_kfree_skb(rx->skb);
    return RX_QUEUED;

 queue:
    rx->skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
    skb_queue_tail(&sdata->skb_queue, rx->skb);
    ieee80211_queue_work(&local->hw, &sdata->work);
    if (rx->sta)
        rx->sta->rx_packets++;
    return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
{
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
    int sig = 0;

    /* skip known-bad action frames and return them in the next handler */
    if (status->rx_flags & IEEE80211_RX_MALFORMED_ACTION_FRM)
        return RX_CONTINUE;

    /*
     * Getting here means the kernel doesn't know how to handle
     * it, but maybe userspace does ... include returned frames
     * so userspace can register for those to know whether ones
     * it transmitted were processed or returned.
     */

    if (rx->local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
        sig = status->signal;

    if (cfg80211_rx_mgmt(&rx->sdata->wdev, status->freq, sig,
                 rx->skb->data, rx->skb->len,
                 GFP_ATOMIC)) {
        if (rx->sta)
            rx->sta->rx_packets++;
        dev_kfree_skb(rx->skb);
        return RX_QUEUED;
    }


    return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_action_return(struct ieee80211_rx_data *rx)
{
    struct ieee80211_local *local = rx->local;
    struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
    struct sk_buff *nskb;
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

    if (!ieee80211_is_action(mgmt->frame_control))
        return RX_CONTINUE;

    /*
     * For AP mode, hostapd is responsible for handling any action
     * frames that we didn't handle, including returning unknown
     * ones. For all other modes we will return them to the sender,
     * setting the 0x80 bit in the action category, as required by
     * 802.11-2012 9.24.4.
     * Newer versions of hostapd shall also use the management frame
     * registration mechanisms, but older ones still use cooked
     * monitor interfaces so push all frames there.
     */
    if (!(status->rx_flags & IEEE80211_RX_MALFORMED_ACTION_FRM) &&
        (sdata->vif.type == NL80211_IFTYPE_AP ||
         sdata->vif.type == NL80211_IFTYPE_AP_VLAN))
        return RX_DROP_MONITOR;

    if (is_multicast_ether_addr(mgmt->da))
        return RX_DROP_MONITOR;

    /* do not return rejected action frames */
    if (mgmt->u.action.category & 0x80)
        return RX_DROP_UNUSABLE;

    nskb = skb_copy_expand(rx->skb, local->hw.extra_tx_headroom, 0,
                   GFP_ATOMIC);
    if (nskb) {
        struct ieee80211_mgmt *nmgmt = (void *)nskb->data;

        nmgmt->u.action.category |= 0x80;
        memcpy(nmgmt->da, nmgmt->sa, ETH_ALEN);
        memcpy(nmgmt->sa, rx->sdata->vif.addr, ETH_ALEN);

        memset(nskb->cb, 0, sizeof(nskb->cb));

        ieee80211_tx_skb(rx->sdata, nskb);
    }
    dev_kfree_skb(rx->skb);
    return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_mgmt(struct ieee80211_rx_data *rx)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_mgmt *mgmt = (void *)rx->skb->data;
    __le16 stype;

    stype = mgmt->frame_control & cpu_to_le16(IEEE80211_FCTL_STYPE);

    if (!ieee80211_vif_is_mesh(&sdata->vif) &&
        sdata->vif.type != NL80211_IFTYPE_ADHOC &&
        sdata->vif.type != NL80211_IFTYPE_STATION)
        return RX_DROP_MONITOR;

    switch (stype) {
    case cpu_to_le16(IEEE80211_STYPE_AUTH):
    case cpu_to_le16(IEEE80211_STYPE_BEACON):
    case cpu_to_le16(IEEE80211_STYPE_PROBE_RESP):
        /* process for all: mesh, mlme, ibss */
        break;
    case cpu_to_le16(IEEE80211_STYPE_ASSOC_RESP):
    case cpu_to_le16(IEEE80211_STYPE_REASSOC_RESP):
    case cpu_to_le16(IEEE80211_STYPE_DEAUTH):
    case cpu_to_le16(IEEE80211_STYPE_DISASSOC):
        if (is_multicast_ether_addr(mgmt->da) &&
            !is_broadcast_ether_addr(mgmt->da))
            return RX_DROP_MONITOR;

        /* process only for station */
        if (sdata->vif.type != NL80211_IFTYPE_STATION)
            return RX_DROP_MONITOR;
        break;
    case cpu_to_le16(IEEE80211_STYPE_PROBE_REQ):
        /* process only for ibss */
        if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
            return RX_DROP_MONITOR;
        break;
    default:
        return RX_DROP_MONITOR;
    }

    /* queue up frame and kick off work to process it */
    rx->skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
    skb_queue_tail(&sdata->skb_queue, rx->skb);
    ieee80211_queue_work(&rx->local->hw, &sdata->work);
    if (rx->sta)
        rx->sta->rx_packets++;

    return RX_QUEUED;
}

/* TODO: use IEEE80211_RX_FRAGMENTED */
static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
                    struct ieee80211_rate *rate)
{
    struct ieee80211_sub_if_data *sdata;
    struct ieee80211_local *local = rx->local;
    struct sk_buff *skb = rx->skb, *skb2;
    struct net_device *prev_dev = NULL;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    int needed_headroom;

    /*
     * If cooked monitor has been processed already, then
     * don't do it again. If not, set the flag.
     */
    if (rx->flags & IEEE80211_RX_CMNTR)
        goto out_free_skb;
    rx->flags |= IEEE80211_RX_CMNTR;

    /* If there are no cooked monitor interfaces, just free the SKB */
    if (!local->cooked_mntrs)
        goto out_free_skb;

    /* room for the radiotap header based on driver features */
    needed_headroom = ieee80211_rx_radiotap_len(local, status);

    if (skb_headroom(skb) < needed_headroom &&
        pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC))
        goto out_free_skb;

    /* prepend radiotap information */
    ieee80211_add_rx_radiotap_header(local, skb, rate, needed_headroom,
                     false);

    skb_set_mac_header(skb, 0);
    skb->ip_summed = CHECKSUM_UNNECESSARY;
    skb->pkt_type = PACKET_OTHERHOST;
    skb->protocol = htons(ETH_P_802_2);

    list_for_each_entry_rcu(sdata, &local->interfaces, list) {
        if (!ieee80211_sdata_running(sdata))
            continue;

        if (sdata->vif.type != NL80211_IFTYPE_MONITOR ||
            !(sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES))
            continue;

        if (prev_dev) {
            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (skb2) {
                skb2->dev = prev_dev;
                netif_receive_skb(skb2);
            }
        }

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

    if (prev_dev) {
        skb->dev = prev_dev;
        netif_receive_skb(skb);
        return;
    }

 out_free_skb:
    dev_kfree_skb(skb);
}

static void ieee80211_rx_handlers_result(struct ieee80211_rx_data *rx,
                     ieee80211_rx_result res)
{
    switch (res) {
    case RX_DROP_MONITOR:
        I802_DEBUG_INC(rx->sdata->local->rx_handlers_drop);
        if (rx->sta)
            rx->sta->rx_dropped++;
        /* fall through */
    case RX_CONTINUE: {
        struct ieee80211_rate *rate = NULL;
        struct ieee80211_supported_band *sband;
        struct ieee80211_rx_status *status;

        status = IEEE80211_SKB_RXCB((rx->skb));

        sband = rx->local->hw.wiphy->bands[status->band];
        if (!(status->flag & RX_FLAG_HT))
            rate = &sband->bitrates[status->rate_idx];

        ieee80211_rx_cooked_monitor(rx, rate);
        break;
        }
    case RX_DROP_UNUSABLE:
        I802_DEBUG_INC(rx->sdata->local->rx_handlers_drop);
        if (rx->sta)
            rx->sta->rx_dropped++;
        dev_kfree_skb(rx->skb);
        break;
    case RX_QUEUED:
        I802_DEBUG_INC(rx->sdata->local->rx_handlers_queued);
        break;
    }
}

static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx)
{
    ieee80211_rx_result res = RX_DROP_MONITOR;
    struct sk_buff *skb;

#define CALL_RXH(rxh)           \
    do {                \
        res = rxh(rx);      \
        if (res != RX_CONTINUE) \
            goto rxh_next;  \
    } while (0);

    spin_lock(&rx->local->rx_skb_queue.lock);
    if (rx->local->running_rx_handler)
        goto unlock;

    rx->local->running_rx_handler = true;

    while ((skb = __skb_dequeue(&rx->local->rx_skb_queue))) {
        spin_unlock(&rx->local->rx_skb_queue.lock);

        /*
         * all the other fields are valid across frames
         * that belong to an aMPDU since they are on the
         * same TID from the same station
         */
        rx->skb = skb;

        CALL_RXH(ieee80211_rx_h_decrypt)
        CALL_RXH(ieee80211_rx_h_check_more_data)
        CALL_RXH(ieee80211_rx_h_uapsd_and_pspoll)
        CALL_RXH(ieee80211_rx_h_sta_process)
        CALL_RXH(ieee80211_rx_h_defragment)
        CALL_RXH(ieee80211_rx_h_michael_mic_verify)
        /* must be after MMIC verify so header is counted in MPDU mic */
#ifdef CONFIG_MAC80211_MESH
        if (ieee80211_vif_is_mesh(&rx->sdata->vif))
            CALL_RXH(ieee80211_rx_h_mesh_fwding);
#endif
        CALL_RXH(ieee80211_rx_h_amsdu)
        CALL_RXH(ieee80211_rx_h_data)
        CALL_RXH(ieee80211_rx_h_ctrl);
        CALL_RXH(ieee80211_rx_h_mgmt_check)
        CALL_RXH(ieee80211_rx_h_action)
        CALL_RXH(ieee80211_rx_h_userspace_mgmt)
        CALL_RXH(ieee80211_rx_h_action_return)
        CALL_RXH(ieee80211_rx_h_mgmt)

 rxh_next:
        ieee80211_rx_handlers_result(rx, res);
        spin_lock(&rx->local->rx_skb_queue.lock);
#undef CALL_RXH
    }

    rx->local->running_rx_handler = false;

 unlock:
    spin_unlock(&rx->local->rx_skb_queue.lock);
}

static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx)
{
    ieee80211_rx_result res = RX_DROP_MONITOR;

#define CALL_RXH(rxh)           \
    do {                \
        res = rxh(rx);      \
        if (res != RX_CONTINUE) \
            goto rxh_next;  \
    } while (0);

    CALL_RXH(ieee80211_rx_h_check)

    ieee80211_rx_reorder_ampdu(rx);

    ieee80211_rx_handlers(rx);
    return;

 rxh_next:
    ieee80211_rx_handlers_result(rx, res);

#undef CALL_RXH
}

/*
 * This function makes calls into the RX path, therefore
 * it has to be invoked under RCU read lock.
 */
void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)
{
    struct ieee80211_rx_data rx = {
        .sta = sta,
        .sdata = sta->sdata,
        .local = sta->local,
        /* This is OK -- must be QoS data frame */
        .security_idx = tid,
        .seqno_idx = tid,
        .flags = 0,
    };
    struct tid_ampdu_rx *tid_agg_rx;

    tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
    if (!tid_agg_rx)
        return;

    spin_lock(&tid_agg_rx->reorder_lock);
    ieee80211_sta_reorder_release(sta->sdata, tid_agg_rx);
    spin_unlock(&tid_agg_rx->reorder_lock);

    ieee80211_rx_handlers(&rx);
}

/* main receive path */

static int prepare_for_handlers(struct ieee80211_rx_data *rx,
                struct ieee80211_hdr *hdr)
{
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct sk_buff *skb = rx->skb;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    u8 *bssid = ieee80211_get_bssid(hdr, skb->len, sdata->vif.type);
    int multicast = is_multicast_ether_addr(hdr->addr1);

    switch (sdata->vif.type) {
    case NL80211_IFTYPE_STATION:
        if (!bssid && !sdata->u.mgd.use_4addr)
            return 0;
        if (!multicast &&
            !ether_addr_equal(sdata->vif.addr, hdr->addr1)) {
            if (!(sdata->dev->flags & IFF_PROMISC) ||
                sdata->u.mgd.use_4addr)
                return 0;
            status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
        }
        break;
    case NL80211_IFTYPE_ADHOC:
        if (!bssid)
            return 0;
        if (ieee80211_is_beacon(hdr->frame_control)) {
            return 1;
        } else if (!ieee80211_bssid_match(bssid, sdata->u.ibss.bssid)) {
            return 0;
        } else if (!multicast &&
               !ether_addr_equal(sdata->vif.addr, hdr->addr1)) {
            if (!(sdata->dev->flags & IFF_PROMISC))
                return 0;
            status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
        } else if (!rx->sta) {
            int rate_idx;
            if (status->flag & RX_FLAG_HT)
                rate_idx = 0; /* TODO: HT rates */
            else
                rate_idx = status->rate_idx;
            ieee80211_ibss_rx_no_sta(sdata, bssid, hdr->addr2,
                         BIT(rate_idx));
        }
        break;
    case NL80211_IFTYPE_MESH_POINT:
        if (!multicast &&
            !ether_addr_equal(sdata->vif.addr, hdr->addr1)) {
            if (!(sdata->dev->flags & IFF_PROMISC))
                return 0;

            status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
        }
        break;
    case NL80211_IFTYPE_AP_VLAN:
    case NL80211_IFTYPE_AP:
        if (!bssid) {
            if (!ether_addr_equal(sdata->vif.addr, hdr->addr1))
                return 0;
        } else if (!ieee80211_bssid_match(bssid, sdata->vif.addr)) {
            /*
             * Accept public action frames even when the
             * BSSID doesn't match, this is used for P2P
             * and location updates. Note that mac80211
             * itself never looks at these frames.
             */
            if (ieee80211_is_public_action(hdr, skb->len))
                return 1;
            if (!ieee80211_is_beacon(hdr->frame_control))
                return 0;
            status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
        }
        break;
    case NL80211_IFTYPE_WDS:
        if (bssid || !ieee80211_is_data(hdr->frame_control))
            return 0;
        if (!ether_addr_equal(sdata->u.wds.remote_addr, hdr->addr2))
            return 0;
        break;
    case NL80211_IFTYPE_P2P_DEVICE:
        if (!ieee80211_is_public_action(hdr, skb->len) &&
            !ieee80211_is_probe_req(hdr->frame_control) &&
            !ieee80211_is_probe_resp(hdr->frame_control) &&
            !ieee80211_is_beacon(hdr->frame_control))
            return 0;
        if (!ether_addr_equal(sdata->vif.addr, hdr->addr1))
            status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
        break;
    default:
        /* should never get here */
        WARN_ON_ONCE(1);
        break;
    }

    return 1;
}

/*
 * This function returns whether or not the SKB
 * was destined for RX processing or not, which,
 * if consume is true, is equivalent to whether
 * or not the skb was consumed.
 */
static bool ieee80211_prepare_and_rx_handle(struct ieee80211_rx_data *rx,
                        struct sk_buff *skb, bool consume)
{
    struct ieee80211_local *local = rx->local;
    struct ieee80211_sub_if_data *sdata = rx->sdata;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    struct ieee80211_hdr *hdr = (void *)skb->data;
    int prepares;

    rx->skb = skb;
    status->rx_flags |= IEEE80211_RX_RA_MATCH;
    prepares = prepare_for_handlers(rx, hdr);

    if (!prepares)
        return false;

    if (!consume) {
        skb = skb_copy(skb, GFP_ATOMIC);
        if (!skb) {
            if (net_ratelimit())
                wiphy_debug(local->hw.wiphy,
                    "failed to copy skb for %s\n",
                    sdata->name);
            return true;
        }

        rx->skb = skb;
    }

    ieee80211_invoke_rx_handlers(rx);
    return true;
}

/*
 * This is the actual Rx frames handler. as it blongs to Rx path it must
 * be called with rcu_read_lock protection.
 */
static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
                     struct sk_buff *skb)
{
    struct ieee80211_local *local = hw_to_local(hw);
    struct ieee80211_sub_if_data *sdata;
    struct ieee80211_hdr *hdr;
    __le16 fc;
    struct ieee80211_rx_data rx;
    struct ieee80211_sub_if_data *prev;
    struct sta_info *sta, *tmp, *prev_sta;
    int err = 0;

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

    if (ieee80211_is_data(fc) || ieee80211_is_mgmt(fc))
        local->dot11ReceivedFragmentCount++;

    if (ieee80211_is_mgmt(fc)) {
        /* drop frame if too short for header */
        if (skb->len < ieee80211_hdrlen(fc))
            err = -ENOBUFS;
        else
            err = skb_linearize(skb);
    } else {
        err = !pskb_may_pull(skb, ieee80211_hdrlen(fc));
    }

    if (err) {
        dev_kfree_skb(skb);
        return;
    }

    hdr = (struct ieee80211_hdr *)skb->data;
    ieee80211_parse_qos(&rx);
    ieee80211_verify_alignment(&rx);

    if (unlikely(ieee80211_is_probe_resp(hdr->frame_control) ||
             ieee80211_is_beacon(hdr->frame_control)))
        ieee80211_scan_rx(local, skb);

    if (ieee80211_is_data(fc)) {
        prev_sta = NULL;

        for_each_sta_info(local, hdr->addr2, sta, tmp) {
            if (!prev_sta) {
                prev_sta = sta;
                continue;
            }

            rx.sta = prev_sta;
            rx.sdata = prev_sta->sdata;
            ieee80211_prepare_and_rx_handle(&rx, skb, false);

            prev_sta = sta;
        }

        if (prev_sta) {
            rx.sta = prev_sta;
            rx.sdata = prev_sta->sdata;

            if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
                return;
            goto out;
        }
    }

    prev = NULL;

    list_for_each_entry_rcu(sdata, &local->interfaces, list) {
        if (!ieee80211_sdata_running(sdata))
            continue;

        if (sdata->vif.type == NL80211_IFTYPE_MONITOR ||
            sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
            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;
        }

        rx.sta = sta_info_get_bss(prev, hdr->addr2);
        rx.sdata = prev;
        ieee80211_prepare_and_rx_handle(&rx, skb, false);

        prev = sdata;
    }

    if (prev) {
        rx.sta = sta_info_get_bss(prev, hdr->addr2);
        rx.sdata = prev;

        if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
            return;
    }

 out:
    dev_kfree_skb(skb);
}

/*
 * 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_local *local = hw_to_local(hw);
    struct ieee80211_rate *rate = NULL;
    struct ieee80211_supported_band *sband;
    struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

    WARN_ON_ONCE(softirq_count() == 0);

    if (WARN_ON(status->band < 0 ||
            status->band >= IEEE80211_NUM_BANDS))
        goto drop;

    sband = local->hw.wiphy->bands[status->band];
    if (WARN_ON(!sband))
        goto drop;

    /*
     * If we're suspending, it is possible although not too likely
     * that we'd be receiving frames after having already partially
     * quiesced the stack. We can't process such frames then since
     * that might, for example, cause stations to be added or other
     * driver callbacks be invoked.
     */
    if (unlikely(local->quiescing || local->suspended))
        goto drop;

    /* We might be during a HW reconfig, prevent Rx for the same reason */
    if (unlikely(local->in_reconfig))
        goto drop;

    /*
     * The same happens when we're not even started,
     * but that's worth a warning.
     */
    if (WARN_ON(!local->started))
        goto drop;

    if (likely(!(status->flag & RX_FLAG_FAILED_PLCP_CRC))) {
        /*
         * Validate the rate, unless a PLCP error means that
         * we probably can't have a valid rate here anyway.
         */

        if (status->flag & RX_FLAG_HT) {
            /*
             * rate_idx is MCS index, which can be [0-76]
             * as documented on:
             *
             * http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n
             *
             * Anything else would be some sort of driver or
             * hardware error. The driver should catch hardware
             * errors.
             */
            if (WARN((status->rate_idx < 0 ||
                 status->rate_idx > 76),
                 "Rate marked as an HT rate but passed "
                 "status->rate_idx is not "
                 "an MCS index [0-76]: %d (0x%02x)\n",
                 status->rate_idx,
                 status->rate_idx))
                goto drop;
        } else {
            if (WARN_ON(status->rate_idx < 0 ||
                    status->rate_idx >= sband->n_bitrates))
                goto drop;
            rate = &sband->bitrates[status->rate_idx];
        }
    }

    status->rx_flags = 0;

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

    /*
     * Frames with failed FCS/PLCP checksum are not returned,
     * all other frames are returned without radiotap header
     * if it was previously present.
     * Also, frames with less than 16 bytes are dropped.
     */
    skb = ieee80211_rx_monitor(local, skb, rate);
    if (!skb) {
        rcu_read_unlock();
        return;
    }

    ieee80211_tpt_led_trig_rx(local,
            ((struct ieee80211_hdr *)skb->data)->frame_control,
            skb->len);
    __ieee80211_rx_handle_packet(hw, skb);

    rcu_read_unlock();

    return;
 drop:
    kfree_skb(skb);
}
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_local *local = hw_to_local(hw);

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

    skb->pkt_type = IEEE80211_RX_MSG;
    skb_queue_tail(&local->skb_queue, skb);
    tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_rx_irqsafe);