hostap_80211_rx.c

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#include <linux/etherdevice.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/lib80211.h>
#include <linux/if_arp.h>

#include "hostap_80211.h"
#include "hostap.h"
#include "hostap_ap.h"

/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
static unsigned char rfc1042_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
static unsigned char bridge_tunnel_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
/* No encapsulation header if EtherType < 0x600 (=length) */

void hostap_dump_rx_80211(const char *name, struct sk_buff *skb,
              struct hostap_80211_rx_status *rx_stats)
{
    struct ieee80211_hdr *hdr;
    u16 fc;

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

    printk(KERN_DEBUG "%s: RX signal=%d noise=%d rate=%d len=%d "
           "jiffies=%ld\n",
           name, rx_stats->signal, rx_stats->noise, rx_stats->rate,
           skb->len, jiffies);

    if (skb->len < 2)
        return;

    fc = le16_to_cpu(hdr->frame_control);
    printk(KERN_DEBUG "   FC=0x%04x (type=%d:%d)%s%s",
           fc, (fc & IEEE80211_FCTL_FTYPE) >> 2,
           (fc & IEEE80211_FCTL_STYPE) >> 4,
           fc & IEEE80211_FCTL_TODS ? " [ToDS]" : "",
           fc & IEEE80211_FCTL_FROMDS ? " [FromDS]" : "");

    if (skb->len < IEEE80211_DATA_HDR3_LEN) {
        printk("\n");
        return;
    }

    printk(" dur=0x%04x seq=0x%04x\n", le16_to_cpu(hdr->duration_id),
           le16_to_cpu(hdr->seq_ctrl));

    printk(KERN_DEBUG "   A1=%pM", hdr->addr1);
    printk(" A2=%pM", hdr->addr2);
    printk(" A3=%pM", hdr->addr3);
    if (skb->len >= 30)
        printk(" A4=%pM", hdr->addr4);
    printk("\n");
}


/* Send RX frame to netif with 802.11 (and possible prism) header.
 * Called from hardware or software IRQ context. */
int prism2_rx_80211(struct net_device *dev, struct sk_buff *skb,
            struct hostap_80211_rx_status *rx_stats, int type)
{
    struct hostap_interface *iface;
    local_info_t *local;
    int hdrlen, phdrlen, head_need, tail_need;
    u16 fc;
    int prism_header, ret;
    struct ieee80211_hdr *fhdr;

    iface = netdev_priv(dev);
    local = iface->local;

    if (dev->type == ARPHRD_IEEE80211_PRISM) {
        if (local->monitor_type == PRISM2_MONITOR_PRISM) {
            prism_header = 1;
            phdrlen = sizeof(struct linux_wlan_ng_prism_hdr);
        } else { /* local->monitor_type == PRISM2_MONITOR_CAPHDR */
            prism_header = 2;
            phdrlen = sizeof(struct linux_wlan_ng_cap_hdr);
        }
    } else if (dev->type == ARPHRD_IEEE80211_RADIOTAP) {
        prism_header = 3;
        phdrlen = sizeof(struct hostap_radiotap_rx);
    } else {
        prism_header = 0;
        phdrlen = 0;
    }

    fhdr = (struct ieee80211_hdr *) skb->data;
    fc = le16_to_cpu(fhdr->frame_control);

    if (type == PRISM2_RX_MGMT && (fc & IEEE80211_FCTL_VERS)) {
        printk(KERN_DEBUG "%s: dropped management frame with header "
               "version %d\n", dev->name, fc & IEEE80211_FCTL_VERS);
        dev_kfree_skb_any(skb);
        return 0;
    }

    hdrlen = hostap_80211_get_hdrlen(fhdr->frame_control);

    /* check if there is enough room for extra data; if not, expand skb
     * buffer to be large enough for the changes */
    head_need = phdrlen;
    tail_need = 0;
#ifdef PRISM2_ADD_BOGUS_CRC
    tail_need += 4;
#endif /* PRISM2_ADD_BOGUS_CRC */

    head_need -= skb_headroom(skb);
    tail_need -= skb_tailroom(skb);

    if (head_need > 0 || tail_need > 0) {
        if (pskb_expand_head(skb, head_need > 0 ? head_need : 0,
                     tail_need > 0 ? tail_need : 0,
                     GFP_ATOMIC)) {
            printk(KERN_DEBUG "%s: prism2_rx_80211 failed to "
                   "reallocate skb buffer\n", dev->name);
            dev_kfree_skb_any(skb);
            return 0;
        }
    }

    /* We now have an skb with enough head and tail room, so just insert
     * the extra data */

#ifdef PRISM2_ADD_BOGUS_CRC
    memset(skb_put(skb, 4), 0xff, 4); /* Prism2 strips CRC */
#endif /* PRISM2_ADD_BOGUS_CRC */

    if (prism_header == 1) {
        struct linux_wlan_ng_prism_hdr *hdr;
        hdr = (struct linux_wlan_ng_prism_hdr *)
            skb_push(skb, phdrlen);
        memset(hdr, 0, phdrlen);
        hdr->msgcode = LWNG_CAP_DID_BASE;
        hdr->msglen = sizeof(*hdr);
        memcpy(hdr->devname, dev->name, sizeof(hdr->devname));
#define LWNG_SETVAL(f,i,s,l,d) \
hdr->f.did = LWNG_CAP_DID_BASE | (i << 12); \
hdr->f.status = s; hdr->f.len = l; hdr->f.data = d
        LWNG_SETVAL(hosttime, 1, 0, 4, jiffies);
        LWNG_SETVAL(mactime, 2, 0, 4, rx_stats->mac_time);
        LWNG_SETVAL(channel, 3, 1 /* no value */, 4, 0);
        LWNG_SETVAL(rssi, 4, 1 /* no value */, 4, 0);
        LWNG_SETVAL(sq, 5, 1 /* no value */, 4, 0);
        LWNG_SETVAL(signal, 6, 0, 4, rx_stats->signal);
        LWNG_SETVAL(noise, 7, 0, 4, rx_stats->noise);
        LWNG_SETVAL(rate, 8, 0, 4, rx_stats->rate / 5);
        LWNG_SETVAL(istx, 9, 0, 4, 0);
        LWNG_SETVAL(frmlen, 10, 0, 4, skb->len - phdrlen);
#undef LWNG_SETVAL
    } else if (prism_header == 2) {
        struct linux_wlan_ng_cap_hdr *hdr;
        hdr = (struct linux_wlan_ng_cap_hdr *)
            skb_push(skb, phdrlen);
        memset(hdr, 0, phdrlen);
        hdr->version    = htonl(LWNG_CAPHDR_VERSION);
        hdr->length     = htonl(phdrlen);
        hdr->mactime    = __cpu_to_be64(rx_stats->mac_time);
        hdr->hosttime   = __cpu_to_be64(jiffies);
        hdr->phytype    = htonl(4); /* dss_dot11_b */
        hdr->channel    = htonl(local->channel);
        hdr->datarate   = htonl(rx_stats->rate);
        hdr->antenna    = htonl(0); /* unknown */
        hdr->priority   = htonl(0); /* unknown */
        hdr->ssi_type   = htonl(3); /* raw */
        hdr->ssi_signal = htonl(rx_stats->signal);
        hdr->ssi_noise  = htonl(rx_stats->noise);
        hdr->preamble   = htonl(0); /* unknown */
        hdr->encoding   = htonl(1); /* cck */
    } else if (prism_header == 3) {
        struct hostap_radiotap_rx *hdr;
        hdr = (struct hostap_radiotap_rx *)skb_push(skb, phdrlen);
        memset(hdr, 0, phdrlen);
        hdr->hdr.it_len = cpu_to_le16(phdrlen);
        hdr->hdr.it_present =
            cpu_to_le32((1 << IEEE80211_RADIOTAP_TSFT) |
                    (1 << IEEE80211_RADIOTAP_CHANNEL) |
                    (1 << IEEE80211_RADIOTAP_RATE) |
                    (1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL) |
                    (1 << IEEE80211_RADIOTAP_DBM_ANTNOISE));
        hdr->tsft = cpu_to_le64(rx_stats->mac_time);
        hdr->chan_freq = cpu_to_le16(freq_list[local->channel - 1]);
        hdr->chan_flags = cpu_to_le16(IEEE80211_CHAN_CCK |
                         IEEE80211_CHAN_2GHZ);
        hdr->rate = rx_stats->rate / 5;
        hdr->dbm_antsignal = rx_stats->signal;
        hdr->dbm_antnoise = rx_stats->noise;
    }

    ret = skb->len - phdrlen;
    skb->dev = dev;
    skb_reset_mac_header(skb);
    skb_pull(skb, hdrlen);
    if (prism_header)
        skb_pull(skb, phdrlen);
    skb->pkt_type = PACKET_OTHERHOST;
    skb->protocol = cpu_to_be16(ETH_P_802_2);
    memset(skb->cb, 0, sizeof(skb->cb));
    netif_rx(skb);

    return ret;
}


/* Called only as a tasklet (software IRQ) */
static void monitor_rx(struct net_device *dev, struct sk_buff *skb,
               struct hostap_80211_rx_status *rx_stats)
{
    int len;

    len = prism2_rx_80211(dev, skb, rx_stats, PRISM2_RX_MONITOR);
    dev->stats.rx_packets++;
    dev->stats.rx_bytes += len;
}


/* Called only as a tasklet (software IRQ) */
static struct prism2_frag_entry *
prism2_frag_cache_find(local_info_t *local, unsigned int seq,
               unsigned int frag, u8 *src, u8 *dst)
{
    struct prism2_frag_entry *entry;
    int i;

    for (i = 0; i < PRISM2_FRAG_CACHE_LEN; i++) {
        entry = &local->frag_cache[i];
        if (entry->skb != NULL &&
            time_after(jiffies, entry->first_frag_time + 2 * HZ)) {
            printk(KERN_DEBUG "%s: expiring fragment cache entry "
                   "seq=%u last_frag=%u\n",
                   local->dev->name, entry->seq, entry->last_frag);
            dev_kfree_skb(entry->skb);
            entry->skb = NULL;
        }

        if (entry->skb != NULL && entry->seq == seq &&
            (entry->last_frag + 1 == frag || frag == -1) &&
            memcmp(entry->src_addr, src, ETH_ALEN) == 0 &&
            memcmp(entry->dst_addr, dst, ETH_ALEN) == 0)
            return entry;
    }

    return NULL;
}


/* Called only as a tasklet (software IRQ) */
static struct sk_buff *
prism2_frag_cache_get(local_info_t *local, struct ieee80211_hdr *hdr)
{
    struct sk_buff *skb = NULL;
    u16 sc;
    unsigned int frag, seq;
    struct prism2_frag_entry *entry;

    sc = le16_to_cpu(hdr->seq_ctrl);
    frag = sc & IEEE80211_SCTL_FRAG;
    seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

    if (frag == 0) {
        /* Reserve enough space to fit maximum frame length */
        skb = dev_alloc_skb(local->dev->mtu +
                    sizeof(struct ieee80211_hdr) +
                    8 /* LLC */ +
                    2 /* alignment */ +
                    8 /* WEP */ + ETH_ALEN /* WDS */);
        if (skb == NULL)
            return NULL;

        entry = &local->frag_cache[local->frag_next_idx];
        local->frag_next_idx++;
        if (local->frag_next_idx >= PRISM2_FRAG_CACHE_LEN)
            local->frag_next_idx = 0;

        if (entry->skb != NULL)
            dev_kfree_skb(entry->skb);

        entry->first_frag_time = jiffies;
        entry->seq = seq;
        entry->last_frag = frag;
        entry->skb = skb;
        memcpy(entry->src_addr, hdr->addr2, ETH_ALEN);
        memcpy(entry->dst_addr, hdr->addr1, ETH_ALEN);
    } else {
        /* received a fragment of a frame for which the head fragment
         * should have already been received */
        entry = prism2_frag_cache_find(local, seq, frag, hdr->addr2,
                           hdr->addr1);
        if (entry != NULL) {
            entry->last_frag = frag;
            skb = entry->skb;
        }
    }

    return skb;
}


/* Called only as a tasklet (software IRQ) */
static int prism2_frag_cache_invalidate(local_info_t *local,
                    struct ieee80211_hdr *hdr)
{
    u16 sc;
    unsigned int seq;
    struct prism2_frag_entry *entry;

    sc = le16_to_cpu(hdr->seq_ctrl);
    seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

    entry = prism2_frag_cache_find(local, seq, -1, hdr->addr2, hdr->addr1);

    if (entry == NULL) {
        printk(KERN_DEBUG "%s: could not invalidate fragment cache "
               "entry (seq=%u)\n",
               local->dev->name, seq);
        return -1;
    }

    entry->skb = NULL;
    return 0;
}


static struct hostap_bss_info *__hostap_get_bss(local_info_t *local, u8 *bssid,
                        u8 *ssid, size_t ssid_len)
{
    struct list_head *ptr;
    struct hostap_bss_info *bss;

    list_for_each(ptr, &local->bss_list) {
        bss = list_entry(ptr, struct hostap_bss_info, list);
        if (memcmp(bss->bssid, bssid, ETH_ALEN) == 0 &&
            (ssid == NULL ||
             (ssid_len == bss->ssid_len &&
              memcmp(ssid, bss->ssid, ssid_len) == 0))) {
            list_move(&bss->list, &local->bss_list);
            return bss;
        }
    }

    return NULL;
}


static struct hostap_bss_info *__hostap_add_bss(local_info_t *local, u8 *bssid,
                        u8 *ssid, size_t ssid_len)
{
    struct hostap_bss_info *bss;

    if (local->num_bss_info >= HOSTAP_MAX_BSS_COUNT) {
        bss = list_entry(local->bss_list.prev,
                 struct hostap_bss_info, list);
        list_del(&bss->list);
        local->num_bss_info--;
    } else {
        bss = kmalloc(sizeof(*bss), GFP_ATOMIC);
        if (bss == NULL)
            return NULL;
    }

    memset(bss, 0, sizeof(*bss));
    memcpy(bss->bssid, bssid, ETH_ALEN);
    memcpy(bss->ssid, ssid, ssid_len);
    bss->ssid_len = ssid_len;
    local->num_bss_info++;
    list_add(&bss->list, &local->bss_list);
    return bss;
}


static void __hostap_expire_bss(local_info_t *local)
{
    struct hostap_bss_info *bss;

    while (local->num_bss_info > 0) {
        bss = list_entry(local->bss_list.prev,
                 struct hostap_bss_info, list);
        if (!time_after(jiffies, bss->last_update + 60 * HZ))
            break;

        list_del(&bss->list);
        local->num_bss_info--;
        kfree(bss);
    }
}


/* Both IEEE 802.11 Beacon and Probe Response frames have similar structure, so
 * the same routine can be used to parse both of them. */
static void hostap_rx_sta_beacon(local_info_t *local, struct sk_buff *skb,
                 int stype)
{
    struct hostap_ieee80211_mgmt *mgmt;
    int left, chan = 0;
    u8 *pos;
    u8 *ssid = NULL, *wpa = NULL, *rsn = NULL;
    size_t ssid_len = 0, wpa_len = 0, rsn_len = 0;
    struct hostap_bss_info *bss;

    if (skb->len < IEEE80211_MGMT_HDR_LEN + sizeof(mgmt->u.beacon))
        return;

    mgmt = (struct hostap_ieee80211_mgmt *) skb->data;
    pos = mgmt->u.beacon.variable;
    left = skb->len - (pos - skb->data);

    while (left >= 2) {
        if (2 + pos[1] > left)
            return; /* parse failed */
        switch (*pos) {
        case WLAN_EID_SSID:
            ssid = pos + 2;
            ssid_len = pos[1];
            break;
        case WLAN_EID_GENERIC:
            if (pos[1] >= 4 &&
                pos[2] == 0x00 && pos[3] == 0x50 &&
                pos[4] == 0xf2 && pos[5] == 1) {
                wpa = pos;
                wpa_len = pos[1] + 2;
            }
            break;
        case WLAN_EID_RSN:
            rsn = pos;
            rsn_len = pos[1] + 2;
            break;
        case WLAN_EID_DS_PARAMS:
            if (pos[1] >= 1)
                chan = pos[2];
            break;
        }
        left -= 2 + pos[1];
        pos += 2 + pos[1];
    }

    if (wpa_len > MAX_WPA_IE_LEN)
        wpa_len = MAX_WPA_IE_LEN;
    if (rsn_len > MAX_WPA_IE_LEN)
        rsn_len = MAX_WPA_IE_LEN;
    if (ssid_len > sizeof(bss->ssid))
        ssid_len = sizeof(bss->ssid);

    spin_lock(&local->lock);
    bss = __hostap_get_bss(local, mgmt->bssid, ssid, ssid_len);
    if (bss == NULL)
        bss = __hostap_add_bss(local, mgmt->bssid, ssid, ssid_len);
    if (bss) {
        bss->last_update = jiffies;
        bss->count++;
        bss->capab_info = le16_to_cpu(mgmt->u.beacon.capab_info);
        if (wpa) {
            memcpy(bss->wpa_ie, wpa, wpa_len);
            bss->wpa_ie_len = wpa_len;
        } else
            bss->wpa_ie_len = 0;
        if (rsn) {
            memcpy(bss->rsn_ie, rsn, rsn_len);
            bss->rsn_ie_len = rsn_len;
        } else
            bss->rsn_ie_len = 0;
        bss->chan = chan;
    }
    __hostap_expire_bss(local);
    spin_unlock(&local->lock);
}


static int
hostap_rx_frame_mgmt(local_info_t *local, struct sk_buff *skb,
             struct hostap_80211_rx_status *rx_stats, u16 type,
             u16 stype)
{
    if (local->iw_mode == IW_MODE_MASTER)
        hostap_update_sta_ps(local, (struct ieee80211_hdr *) skb->data);

    if (local->hostapd && type == IEEE80211_FTYPE_MGMT) {
        if (stype == IEEE80211_STYPE_BEACON &&
            local->iw_mode == IW_MODE_MASTER) {
            struct sk_buff *skb2;
            /* Process beacon frames also in kernel driver to
             * update STA(AP) table statistics */
            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (skb2)
                hostap_rx(skb2->dev, skb2, rx_stats);
        }

        /* send management frames to the user space daemon for
         * processing */
        local->apdevstats.rx_packets++;
        local->apdevstats.rx_bytes += skb->len;
        if (local->apdev == NULL)
            return -1;
        prism2_rx_80211(local->apdev, skb, rx_stats, PRISM2_RX_MGMT);
        return 0;
    }

    if (local->iw_mode == IW_MODE_MASTER) {
        if (type != IEEE80211_FTYPE_MGMT &&
            type != IEEE80211_FTYPE_CTL) {
            printk(KERN_DEBUG "%s: unknown management frame "
                   "(type=0x%02x, stype=0x%02x) dropped\n",
                   skb->dev->name, type >> 2, stype >> 4);
            return -1;
        }

        hostap_rx(skb->dev, skb, rx_stats);
        return 0;
    } else if (type == IEEE80211_FTYPE_MGMT &&
           (stype == IEEE80211_STYPE_BEACON ||
            stype == IEEE80211_STYPE_PROBE_RESP)) {
        hostap_rx_sta_beacon(local, skb, stype);
        return -1;
    } else if (type == IEEE80211_FTYPE_MGMT &&
           (stype == IEEE80211_STYPE_ASSOC_RESP ||
            stype == IEEE80211_STYPE_REASSOC_RESP)) {
        /* Ignore (Re)AssocResp silently since these are not currently
         * needed but are still received when WPA/RSN mode is enabled.
         */
        return -1;
    } else {
        printk(KERN_DEBUG "%s: hostap_rx_frame_mgmt: dropped unhandled"
               " management frame in non-Host AP mode (type=%d:%d)\n",
               skb->dev->name, type >> 2, stype >> 4);
        return -1;
    }
}


/* Called only as a tasklet (software IRQ) */
static struct net_device *prism2_rx_get_wds(local_info_t *local,
                           u8 *addr)
{
    struct hostap_interface *iface = NULL;
    struct list_head *ptr;

    read_lock_bh(&local->iface_lock);
    list_for_each(ptr, &local->hostap_interfaces) {
        iface = list_entry(ptr, struct hostap_interface, list);
        if (iface->type == HOSTAP_INTERFACE_WDS &&
            memcmp(iface->u.wds.remote_addr, addr, ETH_ALEN) == 0)
            break;
        iface = NULL;
    }
    read_unlock_bh(&local->iface_lock);

    return iface ? iface->dev : NULL;
}


static int
hostap_rx_frame_wds(local_info_t *local, struct ieee80211_hdr *hdr, u16 fc,
            struct net_device **wds)
{
    /* FIX: is this really supposed to accept WDS frames only in Master
     * mode? What about Repeater or Managed with WDS frames? */
    if ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) !=
        (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS) &&
        (local->iw_mode != IW_MODE_MASTER || !(fc & IEEE80211_FCTL_TODS)))
        return 0; /* not a WDS frame */

    /* Possible WDS frame: either IEEE 802.11 compliant (if FromDS)
     * or own non-standard frame with 4th address after payload */
    if (memcmp(hdr->addr1, local->dev->dev_addr, ETH_ALEN) != 0 &&
        (hdr->addr1[0] != 0xff || hdr->addr1[1] != 0xff ||
         hdr->addr1[2] != 0xff || hdr->addr1[3] != 0xff ||
         hdr->addr1[4] != 0xff || hdr->addr1[5] != 0xff)) {
        /* RA (or BSSID) is not ours - drop */
        PDEBUG(DEBUG_EXTRA2, "%s: received WDS frame with "
               "not own or broadcast %s=%pM\n",
               local->dev->name,
               fc & IEEE80211_FCTL_FROMDS ? "RA" : "BSSID",
               hdr->addr1);
        return -1;
    }

    /* check if the frame came from a registered WDS connection */
    *wds = prism2_rx_get_wds(local, hdr->addr2);
    if (*wds == NULL && fc & IEEE80211_FCTL_FROMDS &&
        (local->iw_mode != IW_MODE_INFRA ||
         !(local->wds_type & HOSTAP_WDS_AP_CLIENT) ||
         memcmp(hdr->addr2, local->bssid, ETH_ALEN) != 0)) {
        /* require that WDS link has been registered with TA or the
         * frame is from current AP when using 'AP client mode' */
        PDEBUG(DEBUG_EXTRA, "%s: received WDS[4 addr] frame "
               "from unknown TA=%pM\n",
               local->dev->name, hdr->addr2);
        if (local->ap && local->ap->autom_ap_wds)
            hostap_wds_link_oper(local, hdr->addr2, WDS_ADD);
        return -1;
    }

    if (*wds && !(fc & IEEE80211_FCTL_FROMDS) && local->ap &&
        hostap_is_sta_assoc(local->ap, hdr->addr2)) {
        /* STA is actually associated with us even though it has a
         * registered WDS link. Assume it is in 'AP client' mode.
         * Since this is a 3-addr frame, assume it is not (bogus) WDS
         * frame and process it like any normal ToDS frame from
         * associated STA. */
        *wds = NULL;
    }

    return 0;
}


static int hostap_is_eapol_frame(local_info_t *local, struct sk_buff *skb)
{
    struct net_device *dev = local->dev;
    u16 fc, ethertype;
    struct ieee80211_hdr *hdr;
    u8 *pos;

    if (skb->len < 24)
        return 0;

    hdr = (struct ieee80211_hdr *) skb->data;
    fc = le16_to_cpu(hdr->frame_control);

    /* check that the frame is unicast frame to us */
    if ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
        IEEE80211_FCTL_TODS &&
        memcmp(hdr->addr1, dev->dev_addr, ETH_ALEN) == 0 &&
        memcmp(hdr->addr3, dev->dev_addr, ETH_ALEN) == 0) {
        /* ToDS frame with own addr BSSID and DA */
    } else if ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
           IEEE80211_FCTL_FROMDS &&
           memcmp(hdr->addr1, dev->dev_addr, ETH_ALEN) == 0) {
        /* FromDS frame with own addr as DA */
    } else
        return 0;

    if (skb->len < 24 + 8)
        return 0;

    /* check for port access entity Ethernet type */
    pos = skb->data + 24;
    ethertype = (pos[6] << 8) | pos[7];
    if (ethertype == ETH_P_PAE)
        return 1;

    return 0;
}


/* Called only as a tasklet (software IRQ) */
static int
hostap_rx_frame_decrypt(local_info_t *local, struct sk_buff *skb,
            struct lib80211_crypt_data *crypt)
{
    struct ieee80211_hdr *hdr;
    int res, hdrlen;

    if (crypt == NULL || crypt->ops->decrypt_mpdu == NULL)
        return 0;

    hdr = (struct ieee80211_hdr *) skb->data;
    hdrlen = hostap_80211_get_hdrlen(hdr->frame_control);

    if (local->tkip_countermeasures &&
        strcmp(crypt->ops->name, "TKIP") == 0) {
        if (net_ratelimit()) {
            printk(KERN_DEBUG "%s: TKIP countermeasures: dropped "
                   "received packet from %pM\n",
                   local->dev->name, hdr->addr2);
        }
        return -1;
    }

    atomic_inc(&crypt->refcnt);
    res = crypt->ops->decrypt_mpdu(skb, hdrlen, crypt->priv);
    atomic_dec(&crypt->refcnt);
    if (res < 0) {
        printk(KERN_DEBUG "%s: decryption failed (SA=%pM) res=%d\n",
               local->dev->name, hdr->addr2, res);
        local->comm_tallies.rx_discards_wep_undecryptable++;
        return -1;
    }

    return res;
}


/* Called only as a tasklet (software IRQ) */
static int
hostap_rx_frame_decrypt_msdu(local_info_t *local, struct sk_buff *skb,
                 int keyidx, struct lib80211_crypt_data *crypt)
{
    struct ieee80211_hdr *hdr;
    int res, hdrlen;

    if (crypt == NULL || crypt->ops->decrypt_msdu == NULL)
        return 0;

    hdr = (struct ieee80211_hdr *) skb->data;
    hdrlen = hostap_80211_get_hdrlen(hdr->frame_control);

    atomic_inc(&crypt->refcnt);
    res = crypt->ops->decrypt_msdu(skb, keyidx, hdrlen, crypt->priv);
    atomic_dec(&crypt->refcnt);
    if (res < 0) {
        printk(KERN_DEBUG "%s: MSDU decryption/MIC verification failed"
               " (SA=%pM keyidx=%d)\n",
               local->dev->name, hdr->addr2, keyidx);
        return -1;
    }

    return 0;
}


/* All received frames are sent to this function. @skb contains the frame in
 * IEEE 802.11 format, i.e., in the format it was sent over air.
 * This function is called only as a tasklet (software IRQ). */
void hostap_80211_rx(struct net_device *dev, struct sk_buff *skb,
             struct hostap_80211_rx_status *rx_stats)
{
    struct hostap_interface *iface;
    local_info_t *local;
    struct ieee80211_hdr *hdr;
    size_t hdrlen;
    u16 fc, type, stype, sc;
    struct net_device *wds = NULL;
    unsigned int frag;
    u8 *payload;
    struct sk_buff *skb2 = NULL;
    u16 ethertype;
    int frame_authorized = 0;
    int from_assoc_ap = 0;
    u8 dst[ETH_ALEN];
    u8 src[ETH_ALEN];
    struct lib80211_crypt_data *crypt = NULL;
    void *sta = NULL;
    int keyidx = 0;

    iface = netdev_priv(dev);
    local = iface->local;
    iface->stats.rx_packets++;
    iface->stats.rx_bytes += skb->len;

    /* dev is the master radio device; change this to be the default
     * virtual interface (this may be changed to WDS device below) */
    dev = local->ddev;
    iface = netdev_priv(dev);

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

    if (skb->len < 10)
        goto rx_dropped;

    fc = le16_to_cpu(hdr->frame_control);
    type = fc & IEEE80211_FCTL_FTYPE;
    stype = fc & IEEE80211_FCTL_STYPE;
    sc = le16_to_cpu(hdr->seq_ctrl);
    frag = sc & IEEE80211_SCTL_FRAG;
    hdrlen = hostap_80211_get_hdrlen(hdr->frame_control);

    /* Put this code here so that we avoid duplicating it in all
     * Rx paths. - Jean II */
#ifdef IW_WIRELESS_SPY      /* defined in iw_handler.h */
    /* If spy monitoring on */
    if (iface->spy_data.spy_number > 0) {
        struct iw_quality wstats;
        wstats.level = rx_stats->signal;
        wstats.noise = rx_stats->noise;
        wstats.updated = IW_QUAL_LEVEL_UPDATED | IW_QUAL_NOISE_UPDATED
            | IW_QUAL_QUAL_INVALID | IW_QUAL_DBM;
        /* Update spy records */
        wireless_spy_update(dev, hdr->addr2, &wstats);
    }
#endif /* IW_WIRELESS_SPY */
    hostap_update_rx_stats(local->ap, hdr, rx_stats);

    if (local->iw_mode == IW_MODE_MONITOR) {
        monitor_rx(dev, skb, rx_stats);
        return;
    }

    if (local->host_decrypt) {
        int idx = 0;
        if (skb->len >= hdrlen + 3)
            idx = skb->data[hdrlen + 3] >> 6;
        crypt = local->crypt_info.crypt[idx];
        sta = NULL;

        /* Use station specific key to override default keys if the
         * receiver address is a unicast address ("individual RA"). If
         * bcrx_sta_key parameter is set, station specific key is used
         * even with broad/multicast targets (this is against IEEE
         * 802.11, but makes it easier to use different keys with
         * stations that do not support WEP key mapping). */

        if (!(hdr->addr1[0] & 0x01) || local->bcrx_sta_key)
            (void) hostap_handle_sta_crypto(local, hdr, &crypt,
                            &sta);

        /* allow NULL decrypt to indicate an station specific override
         * for default encryption */
        if (crypt && (crypt->ops == NULL ||
                  crypt->ops->decrypt_mpdu == NULL))
            crypt = NULL;

        if (!crypt && (fc & IEEE80211_FCTL_PROTECTED)) {
#if 0
            /* This seems to be triggered by some (multicast?)
             * frames from other than current BSS, so just drop the
             * frames silently instead of filling system log with
             * these reports. */
            printk(KERN_DEBUG "%s: WEP decryption failed (not set)"
                   " (SA=%pM)\n",
                   local->dev->name, hdr->addr2);
#endif
            local->comm_tallies.rx_discards_wep_undecryptable++;
            goto rx_dropped;
        }
    }

    if (type != IEEE80211_FTYPE_DATA) {
        if (type == IEEE80211_FTYPE_MGMT &&
            stype == IEEE80211_STYPE_AUTH &&
            fc & IEEE80211_FCTL_PROTECTED && local->host_decrypt &&
            (keyidx = hostap_rx_frame_decrypt(local, skb, crypt)) < 0)
        {
            printk(KERN_DEBUG "%s: failed to decrypt mgmt::auth "
                   "from %pM\n", dev->name, hdr->addr2);
            /* TODO: could inform hostapd about this so that it
             * could send auth failure report */
            goto rx_dropped;
        }

        if (hostap_rx_frame_mgmt(local, skb, rx_stats, type, stype))
            goto rx_dropped;
        else
            goto rx_exit;
    }

    /* Data frame - extract src/dst addresses */
    if (skb->len < IEEE80211_DATA_HDR3_LEN)
        goto rx_dropped;

    switch (fc & (IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS)) {
    case IEEE80211_FCTL_FROMDS:
        memcpy(dst, hdr->addr1, ETH_ALEN);
        memcpy(src, hdr->addr3, ETH_ALEN);
        break;
    case IEEE80211_FCTL_TODS:
        memcpy(dst, hdr->addr3, ETH_ALEN);
        memcpy(src, hdr->addr2, ETH_ALEN);
        break;
    case IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS:
        if (skb->len < IEEE80211_DATA_HDR4_LEN)
            goto rx_dropped;
        memcpy(dst, hdr->addr3, ETH_ALEN);
        memcpy(src, hdr->addr4, ETH_ALEN);
        break;
    case 0:
        memcpy(dst, hdr->addr1, ETH_ALEN);
        memcpy(src, hdr->addr2, ETH_ALEN);
        break;
    }

    if (hostap_rx_frame_wds(local, hdr, fc, &wds))
        goto rx_dropped;
    if (wds)
        skb->dev = dev = wds;

    if (local->iw_mode == IW_MODE_MASTER && !wds &&
        (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
        IEEE80211_FCTL_FROMDS &&
        local->stadev &&
        memcmp(hdr->addr2, local->assoc_ap_addr, ETH_ALEN) == 0) {
        /* Frame from BSSID of the AP for which we are a client */
        skb->dev = dev = local->stadev;
        from_assoc_ap = 1;
    }

    if ((local->iw_mode == IW_MODE_MASTER ||
         local->iw_mode == IW_MODE_REPEAT) &&
        !from_assoc_ap) {
        switch (hostap_handle_sta_rx(local, dev, skb, rx_stats,
                         wds != NULL)) {
        case AP_RX_CONTINUE_NOT_AUTHORIZED:
            frame_authorized = 0;
            break;
        case AP_RX_CONTINUE:
            frame_authorized = 1;
            break;
        case AP_RX_DROP:
            goto rx_dropped;
        case AP_RX_EXIT:
            goto rx_exit;
        }
    }

    /* Nullfunc frames may have PS-bit set, so they must be passed to
     * hostap_handle_sta_rx() before being dropped here. */
    if (stype != IEEE80211_STYPE_DATA &&
        stype != IEEE80211_STYPE_DATA_CFACK &&
        stype != IEEE80211_STYPE_DATA_CFPOLL &&
        stype != IEEE80211_STYPE_DATA_CFACKPOLL) {
        if (stype != IEEE80211_STYPE_NULLFUNC)
            printk(KERN_DEBUG "%s: RX: dropped data frame "
                   "with no data (type=0x%02x, subtype=0x%02x)\n",
                   dev->name, type >> 2, stype >> 4);
        goto rx_dropped;
    }

    /* skb: hdr + (possibly fragmented, possibly encrypted) payload */

    if (local->host_decrypt && (fc & IEEE80211_FCTL_PROTECTED) &&
        (keyidx = hostap_rx_frame_decrypt(local, skb, crypt)) < 0)
        goto rx_dropped;
    hdr = (struct ieee80211_hdr *) skb->data;

    /* skb: hdr + (possibly fragmented) plaintext payload */

    if (local->host_decrypt && (fc & IEEE80211_FCTL_PROTECTED) &&
        (frag != 0 || (fc & IEEE80211_FCTL_MOREFRAGS))) {
        int flen;
        struct sk_buff *frag_skb =
            prism2_frag_cache_get(local, hdr);
        if (!frag_skb) {
            printk(KERN_DEBUG "%s: Rx cannot get skb from "
                   "fragment cache (morefrag=%d seq=%u frag=%u)\n",
                   dev->name, (fc & IEEE80211_FCTL_MOREFRAGS) != 0,
                   (sc & IEEE80211_SCTL_SEQ) >> 4, frag);
            goto rx_dropped;
        }

        flen = skb->len;
        if (frag != 0)
            flen -= hdrlen;

        if (frag_skb->tail + flen > frag_skb->end) {
            printk(KERN_WARNING "%s: host decrypted and "
                   "reassembled frame did not fit skb\n",
                   dev->name);
            prism2_frag_cache_invalidate(local, hdr);
            goto rx_dropped;
        }

        if (frag == 0) {
            /* copy first fragment (including full headers) into
             * beginning of the fragment cache skb */
            skb_copy_from_linear_data(skb, skb_put(frag_skb, flen),
                          flen);
        } else {
            /* append frame payload to the end of the fragment
             * cache skb */
            skb_copy_from_linear_data_offset(skb, hdrlen,
                             skb_put(frag_skb,
                                 flen), flen);
        }
        dev_kfree_skb(skb);
        skb = NULL;

        if (fc & IEEE80211_FCTL_MOREFRAGS) {
            /* more fragments expected - leave the skb in fragment
             * cache for now; it will be delivered to upper layers
             * after all fragments have been received */
            goto rx_exit;
        }

        /* this was the last fragment and the frame will be
         * delivered, so remove skb from fragment cache */
        skb = frag_skb;
        hdr = (struct ieee80211_hdr *) skb->data;
        prism2_frag_cache_invalidate(local, hdr);
    }

    /* skb: hdr + (possible reassembled) full MSDU payload; possibly still
     * encrypted/authenticated */

    if (local->host_decrypt && (fc & IEEE80211_FCTL_PROTECTED) &&
        hostap_rx_frame_decrypt_msdu(local, skb, keyidx, crypt))
        goto rx_dropped;

    hdr = (struct ieee80211_hdr *) skb->data;
    if (crypt && !(fc & IEEE80211_FCTL_PROTECTED) && !local->open_wep) {
        if (local->ieee_802_1x &&
            hostap_is_eapol_frame(local, skb)) {
            /* pass unencrypted EAPOL frames even if encryption is
             * configured */
            PDEBUG(DEBUG_EXTRA2, "%s: RX: IEEE 802.1X - passing "
                   "unencrypted EAPOL frame\n", local->dev->name);
        } else {
            printk(KERN_DEBUG "%s: encryption configured, but RX "
                   "frame not encrypted (SA=%pM)\n",
                   local->dev->name, hdr->addr2);
            goto rx_dropped;
        }
    }

    if (local->drop_unencrypted && !(fc & IEEE80211_FCTL_PROTECTED) &&
        !hostap_is_eapol_frame(local, skb)) {
        if (net_ratelimit()) {
            printk(KERN_DEBUG "%s: dropped unencrypted RX data "
                   "frame from %pM (drop_unencrypted=1)\n",
                   dev->name, hdr->addr2);
        }
        goto rx_dropped;
    }

    /* skb: hdr + (possible reassembled) full plaintext payload */

    payload = skb->data + hdrlen;
    ethertype = (payload[6] << 8) | payload[7];

    /* If IEEE 802.1X is used, check whether the port is authorized to send
     * the received frame. */
    if (local->ieee_802_1x && local->iw_mode == IW_MODE_MASTER) {
        if (ethertype == ETH_P_PAE) {
            PDEBUG(DEBUG_EXTRA2, "%s: RX: IEEE 802.1X frame\n",
                   dev->name);
            if (local->hostapd && local->apdev) {
                /* Send IEEE 802.1X frames to the user
                 * space daemon for processing */
                prism2_rx_80211(local->apdev, skb, rx_stats,
                        PRISM2_RX_MGMT);
                local->apdevstats.rx_packets++;
                local->apdevstats.rx_bytes += skb->len;
                goto rx_exit;
            }
        } else if (!frame_authorized) {
            printk(KERN_DEBUG "%s: dropped frame from "
                   "unauthorized port (IEEE 802.1X): "
                   "ethertype=0x%04x\n",
                   dev->name, ethertype);
            goto rx_dropped;
        }
    }

    /* convert hdr + possible LLC headers into Ethernet header */
    if (skb->len - hdrlen >= 8 &&
        ((memcmp(payload, rfc1042_header, 6) == 0 &&
          ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
         memcmp(payload, bridge_tunnel_header, 6) == 0)) {
        /* remove RFC1042 or Bridge-Tunnel encapsulation and
         * replace EtherType */
        skb_pull(skb, hdrlen + 6);
        memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
        memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
    } else {
        __be16 len;
        /* Leave Ethernet header part of hdr and full payload */
        skb_pull(skb, hdrlen);
        len = htons(skb->len);
        memcpy(skb_push(skb, 2), &len, 2);
        memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
        memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
    }

    if (wds && ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
            IEEE80211_FCTL_TODS) &&
        skb->len >= ETH_HLEN + ETH_ALEN) {
        /* Non-standard frame: get addr4 from its bogus location after
         * the payload */
        skb_copy_from_linear_data_offset(skb, skb->len - ETH_ALEN,
                         skb->data + ETH_ALEN,
                         ETH_ALEN);
        skb_trim(skb, skb->len - ETH_ALEN);
    }

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

    if (local->iw_mode == IW_MODE_MASTER && !wds &&
        local->ap->bridge_packets) {
        if (dst[0] & 0x01) {
            /* copy multicast frame both to the higher layers and
             * to the wireless media */
            local->ap->bridged_multicast++;
            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (skb2 == NULL)
                printk(KERN_DEBUG "%s: skb_clone failed for "
                       "multicast frame\n", dev->name);
        } else if (hostap_is_sta_authorized(local->ap, dst)) {
            /* send frame directly to the associated STA using
             * wireless media and not passing to higher layers */
            local->ap->bridged_unicast++;
            skb2 = skb;
            skb = NULL;
        }
    }

    if (skb2 != NULL) {
        /* send to wireless media */
        skb2->dev = dev;
        skb2->protocol = cpu_to_be16(ETH_P_802_3);
        skb_reset_mac_header(skb2);
        skb_reset_network_header(skb2);
        /* skb2->network_header += ETH_HLEN; */
        dev_queue_xmit(skb2);
    }

    if (skb) {
        skb->protocol = eth_type_trans(skb, dev);
        memset(skb->cb, 0, sizeof(skb->cb));
        netif_rx(skb);
    }

 rx_exit:
    if (sta)
        hostap_handle_sta_release(sta);
    return;

 rx_dropped:
    dev_kfree_skb(skb);

    dev->stats.rx_dropped++;
    goto rx_exit;
}


EXPORT_SYMBOL(hostap_80211_rx);