scan.c

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/*
 * cfg80211 scan result handling
 *
 * Copyright 2008 Johannes Berg <[email protected]>
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/wireless.h>
#include <linux/nl80211.h>
#include <linux/etherdevice.h>
#include <net/arp.h>
#include <net/cfg80211.h>
#include <net/cfg80211-wext.h>
#include <net/iw_handler.h>
#include "core.h"
#include "nl80211.h"
#include "wext-compat.h"

#define IEEE80211_SCAN_RESULT_EXPIRE    (30 * HZ)

void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
{
    struct cfg80211_scan_request *request;
    struct wireless_dev *wdev;
#ifdef CONFIG_CFG80211_WEXT
    union iwreq_data wrqu;
#endif

    ASSERT_RDEV_LOCK(rdev);

    request = rdev->scan_req;

    if (!request)
        return;

    wdev = request->wdev;

    /*
     * This must be before sending the other events!
     * Otherwise, wpa_supplicant gets completely confused with
     * wext events.
     */
    if (wdev->netdev)
        cfg80211_sme_scan_done(wdev->netdev);

    if (request->aborted)
        nl80211_send_scan_aborted(rdev, wdev);
    else
        nl80211_send_scan_done(rdev, wdev);

#ifdef CONFIG_CFG80211_WEXT
    if (wdev->netdev && !request->aborted) {
        memset(&wrqu, 0, sizeof(wrqu));

        wireless_send_event(wdev->netdev, SIOCGIWSCAN, &wrqu, NULL);
    }
#endif

    if (wdev->netdev)
        dev_put(wdev->netdev);

    rdev->scan_req = NULL;

    /*
     * OK. If this is invoked with "leak" then we can't
     * free this ... but we've cleaned it up anyway. The
     * driver failed to call the scan_done callback, so
     * all bets are off, it might still be trying to use
     * the scan request or not ... if it accesses the dev
     * in there (it shouldn't anyway) then it may crash.
     */
    if (!leak)
        kfree(request);
}

void __cfg80211_scan_done(struct work_struct *wk)
{
    struct cfg80211_registered_device *rdev;

    rdev = container_of(wk, struct cfg80211_registered_device,
                scan_done_wk);

    cfg80211_lock_rdev(rdev);
    ___cfg80211_scan_done(rdev, false);
    cfg80211_unlock_rdev(rdev);
}

void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
{
    WARN_ON(request != wiphy_to_dev(request->wiphy)->scan_req);

    request->aborted = aborted;
    queue_work(cfg80211_wq, &wiphy_to_dev(request->wiphy)->scan_done_wk);
}
EXPORT_SYMBOL(cfg80211_scan_done);

void __cfg80211_sched_scan_results(struct work_struct *wk)
{
    struct cfg80211_registered_device *rdev;

    rdev = container_of(wk, struct cfg80211_registered_device,
                sched_scan_results_wk);

    mutex_lock(&rdev->sched_scan_mtx);

    /* we don't have sched_scan_req anymore if the scan is stopping */
    if (rdev->sched_scan_req)
        nl80211_send_sched_scan_results(rdev,
                        rdev->sched_scan_req->dev);

    mutex_unlock(&rdev->sched_scan_mtx);
}

void cfg80211_sched_scan_results(struct wiphy *wiphy)
{
    /* ignore if we're not scanning */
    if (wiphy_to_dev(wiphy)->sched_scan_req)
        queue_work(cfg80211_wq,
               &wiphy_to_dev(wiphy)->sched_scan_results_wk);
}
EXPORT_SYMBOL(cfg80211_sched_scan_results);

void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

    mutex_lock(&rdev->sched_scan_mtx);
    __cfg80211_stop_sched_scan(rdev, true);
    mutex_unlock(&rdev->sched_scan_mtx);
}
EXPORT_SYMBOL(cfg80211_sched_scan_stopped);

int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
                   bool driver_initiated)
{
    struct net_device *dev;

    lockdep_assert_held(&rdev->sched_scan_mtx);

    if (!rdev->sched_scan_req)
        return -ENOENT;

    dev = rdev->sched_scan_req->dev;

    if (!driver_initiated) {
        int err = rdev->ops->sched_scan_stop(&rdev->wiphy, dev);
        if (err)
            return err;
    }

    nl80211_send_sched_scan(rdev, dev, NL80211_CMD_SCHED_SCAN_STOPPED);

    kfree(rdev->sched_scan_req);
    rdev->sched_scan_req = NULL;

    return 0;
}

static void bss_release(struct kref *ref)
{
    struct cfg80211_internal_bss *bss;

    bss = container_of(ref, struct cfg80211_internal_bss, ref);
    if (bss->pub.free_priv)
        bss->pub.free_priv(&bss->pub);

    if (bss->beacon_ies_allocated)
        kfree(bss->pub.beacon_ies);
    if (bss->proberesp_ies_allocated)
        kfree(bss->pub.proberesp_ies);

    BUG_ON(atomic_read(&bss->hold));

    kfree(bss);
}

/* must hold dev->bss_lock! */
void cfg80211_bss_age(struct cfg80211_registered_device *dev,
                      unsigned long age_secs)
{
    struct cfg80211_internal_bss *bss;
    unsigned long age_jiffies = msecs_to_jiffies(age_secs * MSEC_PER_SEC);

    list_for_each_entry(bss, &dev->bss_list, list) {
        bss->ts -= age_jiffies;
    }
}

/* must hold dev->bss_lock! */
static void __cfg80211_unlink_bss(struct cfg80211_registered_device *dev,
                  struct cfg80211_internal_bss *bss)
{
    list_del_init(&bss->list);
    rb_erase(&bss->rbn, &dev->bss_tree);
    kref_put(&bss->ref, bss_release);
}

/* must hold dev->bss_lock! */
void cfg80211_bss_expire(struct cfg80211_registered_device *dev)
{
    struct cfg80211_internal_bss *bss, *tmp;
    bool expired = false;

    list_for_each_entry_safe(bss, tmp, &dev->bss_list, list) {
        if (atomic_read(&bss->hold))
            continue;
        if (!time_after(jiffies, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE))
            continue;
        __cfg80211_unlink_bss(dev, bss);
        expired = true;
    }

    if (expired)
        dev->bss_generation++;
}

const u8 *cfg80211_find_ie(u8 eid, const u8 *ies, int len)
{
    while (len > 2 && ies[0] != eid) {
        len -= ies[1] + 2;
        ies += ies[1] + 2;
    }
    if (len < 2)
        return NULL;
    if (len < 2 + ies[1])
        return NULL;
    return ies;
}
EXPORT_SYMBOL(cfg80211_find_ie);

const u8 *cfg80211_find_vendor_ie(unsigned int oui, u8 oui_type,
                  const u8 *ies, int len)
{
    struct ieee80211_vendor_ie *ie;
    const u8 *pos = ies, *end = ies + len;
    int ie_oui;

    while (pos < end) {
        pos = cfg80211_find_ie(WLAN_EID_VENDOR_SPECIFIC, pos,
                       end - pos);
        if (!pos)
            return NULL;

        if (end - pos < sizeof(*ie))
            return NULL;

        ie = (struct ieee80211_vendor_ie *)pos;
        ie_oui = ie->oui[0] << 16 | ie->oui[1] << 8 | ie->oui[2];
        if (ie_oui == oui && ie->oui_type == oui_type)
            return pos;

        pos += 2 + ie->len;
    }
    return NULL;
}
EXPORT_SYMBOL(cfg80211_find_vendor_ie);

static int cmp_ies(u8 num, u8 *ies1, size_t len1, u8 *ies2, size_t len2)
{
    const u8 *ie1 = cfg80211_find_ie(num, ies1, len1);
    const u8 *ie2 = cfg80211_find_ie(num, ies2, len2);

    /* equal if both missing */
    if (!ie1 && !ie2)
        return 0;
    /* sort missing IE before (left of) present IE */
    if (!ie1)
        return -1;
    if (!ie2)
        return 1;

    /* sort by length first, then by contents */
    if (ie1[1] != ie2[1])
        return ie2[1] - ie1[1];
    return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
}

static bool is_bss(struct cfg80211_bss *a,
           const u8 *bssid,
           const u8 *ssid, size_t ssid_len)
{
    const u8 *ssidie;

    if (bssid && !ether_addr_equal(a->bssid, bssid))
        return false;

    if (!ssid)
        return true;

    ssidie = cfg80211_find_ie(WLAN_EID_SSID,
                  a->information_elements,
                  a->len_information_elements);
    if (!ssidie)
        return false;
    if (ssidie[1] != ssid_len)
        return false;
    return memcmp(ssidie + 2, ssid, ssid_len) == 0;
}

static bool is_mesh_bss(struct cfg80211_bss *a)
{
    const u8 *ie;

    if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
        return false;

    ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
                  a->information_elements,
                  a->len_information_elements);
    if (!ie)
        return false;

    ie = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                  a->information_elements,
                  a->len_information_elements);
    if (!ie)
        return false;

    return true;
}

static bool is_mesh(struct cfg80211_bss *a,
            const u8 *meshid, size_t meshidlen,
            const u8 *meshcfg)
{
    const u8 *ie;

    if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
        return false;

    ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
                  a->information_elements,
                  a->len_information_elements);
    if (!ie)
        return false;
    if (ie[1] != meshidlen)
        return false;
    if (memcmp(ie + 2, meshid, meshidlen))
        return false;

    ie = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                  a->information_elements,
                  a->len_information_elements);
    if (!ie)
        return false;
    if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
        return false;

    /*
     * Ignore mesh capability (last two bytes of the IE) when
     * comparing since that may differ between stations taking
     * part in the same mesh.
     */
    return memcmp(ie + 2, meshcfg,
        sizeof(struct ieee80211_meshconf_ie) - 2) == 0;
}

static int cmp_bss_core(struct cfg80211_bss *a,
            struct cfg80211_bss *b)
{
    int r;

    if (a->channel != b->channel)
        return b->channel->center_freq - a->channel->center_freq;

    if (is_mesh_bss(a) && is_mesh_bss(b)) {
        r = cmp_ies(WLAN_EID_MESH_ID,
                a->information_elements,
                a->len_information_elements,
                b->information_elements,
                b->len_information_elements);
        if (r)
            return r;
        return cmp_ies(WLAN_EID_MESH_CONFIG,
                   a->information_elements,
                   a->len_information_elements,
                   b->information_elements,
                   b->len_information_elements);
    }

    /*
     * we can't use compare_ether_addr here since we need a < > operator.
     * The binary return value of compare_ether_addr isn't enough
     */
    return memcmp(a->bssid, b->bssid, sizeof(a->bssid));
}

static int cmp_bss(struct cfg80211_bss *a,
           struct cfg80211_bss *b)
{
    int r;

    r = cmp_bss_core(a, b);
    if (r)
        return r;

    return cmp_ies(WLAN_EID_SSID,
               a->information_elements,
               a->len_information_elements,
               b->information_elements,
               b->len_information_elements);
}

static int cmp_hidden_bss(struct cfg80211_bss *a,
           struct cfg80211_bss *b)
{
    const u8 *ie1;
    const u8 *ie2;
    int i;
    int r;

    r = cmp_bss_core(a, b);
    if (r)
        return r;

    ie1 = cfg80211_find_ie(WLAN_EID_SSID,
            a->information_elements,
            a->len_information_elements);
    ie2 = cfg80211_find_ie(WLAN_EID_SSID,
            b->information_elements,
            b->len_information_elements);

    /* Key comparator must use same algorithm in any rb-tree
     * search function (order is important), otherwise ordering
     * of items in the tree is broken and search gives incorrect
     * results. This code uses same order as cmp_ies() does. */

    /* sort missing IE before (left of) present IE */
    if (!ie1)
        return -1;
    if (!ie2)
        return 1;

    /* zero-size SSID is used as an indication of the hidden bss */
    if (!ie2[1])
        return 0;

    /* sort by length first, then by contents */
    if (ie1[1] != ie2[1])
        return ie2[1] - ie1[1];

    /* zeroed SSID ie is another indication of a hidden bss */
    for (i = 0; i < ie2[1]; i++)
        if (ie2[i + 2])
            return -1;

    return 0;
}

struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
                      struct ieee80211_channel *channel,
                      const u8 *bssid,
                      const u8 *ssid, size_t ssid_len,
                      u16 capa_mask, u16 capa_val)
{
    struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
    struct cfg80211_internal_bss *bss, *res = NULL;
    unsigned long now = jiffies;

    spin_lock_bh(&dev->bss_lock);

    list_for_each_entry(bss, &dev->bss_list, list) {
        if ((bss->pub.capability & capa_mask) != capa_val)
            continue;
        if (channel && bss->pub.channel != channel)
            continue;
        /* Don't get expired BSS structs */
        if (time_after(now, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE) &&
            !atomic_read(&bss->hold))
            continue;
        if (is_bss(&bss->pub, bssid, ssid, ssid_len)) {
            res = bss;
            kref_get(&res->ref);
            break;
        }
    }

    spin_unlock_bh(&dev->bss_lock);
    if (!res)
        return NULL;
    return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_bss);

struct cfg80211_bss *cfg80211_get_mesh(struct wiphy *wiphy,
                       struct ieee80211_channel *channel,
                       const u8 *meshid, size_t meshidlen,
                       const u8 *meshcfg)
{
    struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
    struct cfg80211_internal_bss *bss, *res = NULL;

    spin_lock_bh(&dev->bss_lock);

    list_for_each_entry(bss, &dev->bss_list, list) {
        if (channel && bss->pub.channel != channel)
            continue;
        if (is_mesh(&bss->pub, meshid, meshidlen, meshcfg)) {
            res = bss;
            kref_get(&res->ref);
            break;
        }
    }

    spin_unlock_bh(&dev->bss_lock);
    if (!res)
        return NULL;
    return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_mesh);


static void rb_insert_bss(struct cfg80211_registered_device *dev,
              struct cfg80211_internal_bss *bss)
{
    struct rb_node **p = &dev->bss_tree.rb_node;
    struct rb_node *parent = NULL;
    struct cfg80211_internal_bss *tbss;
    int cmp;

    while (*p) {
        parent = *p;
        tbss = rb_entry(parent, struct cfg80211_internal_bss, rbn);

        cmp = cmp_bss(&bss->pub, &tbss->pub);

        if (WARN_ON(!cmp)) {
            /* will sort of leak this BSS */
            return;
        }

        if (cmp < 0)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }

    rb_link_node(&bss->rbn, parent, p);
    rb_insert_color(&bss->rbn, &dev->bss_tree);
}

static struct cfg80211_internal_bss *
rb_find_bss(struct cfg80211_registered_device *dev,
        struct cfg80211_internal_bss *res)
{
    struct rb_node *n = dev->bss_tree.rb_node;
    struct cfg80211_internal_bss *bss;
    int r;

    while (n) {
        bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
        r = cmp_bss(&res->pub, &bss->pub);

        if (r == 0)
            return bss;
        else if (r < 0)
            n = n->rb_left;
        else
            n = n->rb_right;
    }

    return NULL;
}

static struct cfg80211_internal_bss *
rb_find_hidden_bss(struct cfg80211_registered_device *dev,
        struct cfg80211_internal_bss *res)
{
    struct rb_node *n = dev->bss_tree.rb_node;
    struct cfg80211_internal_bss *bss;
    int r;

    while (n) {
        bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
        r = cmp_hidden_bss(&res->pub, &bss->pub);

        if (r == 0)
            return bss;
        else if (r < 0)
            n = n->rb_left;
        else
            n = n->rb_right;
    }

    return NULL;
}

static void
copy_hidden_ies(struct cfg80211_internal_bss *res,
         struct cfg80211_internal_bss *hidden)
{
    if (unlikely(res->pub.beacon_ies))
        return;
    if (WARN_ON(!hidden->pub.beacon_ies))
        return;

    res->pub.beacon_ies = kmalloc(hidden->pub.len_beacon_ies, GFP_ATOMIC);
    if (unlikely(!res->pub.beacon_ies))
        return;

    res->beacon_ies_allocated = true;
    res->pub.len_beacon_ies = hidden->pub.len_beacon_ies;
    memcpy(res->pub.beacon_ies, hidden->pub.beacon_ies,
            res->pub.len_beacon_ies);
}

static struct cfg80211_internal_bss *
cfg80211_bss_update(struct cfg80211_registered_device *dev,
            struct cfg80211_internal_bss *res)
{
    struct cfg80211_internal_bss *found = NULL;

    /*
     * The reference to "res" is donated to this function.
     */

    if (WARN_ON(!res->pub.channel)) {
        kref_put(&res->ref, bss_release);
        return NULL;
    }

    res->ts = jiffies;

    spin_lock_bh(&dev->bss_lock);

    found = rb_find_bss(dev, res);

    if (found) {
        found->pub.beacon_interval = res->pub.beacon_interval;
        found->pub.tsf = res->pub.tsf;
        found->pub.signal = res->pub.signal;
        found->pub.capability = res->pub.capability;
        found->ts = res->ts;

        /* Update IEs */
        if (res->pub.proberesp_ies) {
            size_t used = dev->wiphy.bss_priv_size + sizeof(*res);
            size_t ielen = res->pub.len_proberesp_ies;

            if (found->pub.proberesp_ies &&
                !found->proberesp_ies_allocated &&
                ksize(found) >= used + ielen) {
                memcpy(found->pub.proberesp_ies,
                       res->pub.proberesp_ies, ielen);
                found->pub.len_proberesp_ies = ielen;
            } else {
                u8 *ies = found->pub.proberesp_ies;

                if (found->proberesp_ies_allocated)
                    ies = krealloc(ies, ielen, GFP_ATOMIC);
                else
                    ies = kmalloc(ielen, GFP_ATOMIC);

                if (ies) {
                    memcpy(ies, res->pub.proberesp_ies,
                           ielen);
                    found->proberesp_ies_allocated = true;
                    found->pub.proberesp_ies = ies;
                    found->pub.len_proberesp_ies = ielen;
                }
            }

            /* Override possible earlier Beacon frame IEs */
            found->pub.information_elements =
                found->pub.proberesp_ies;
            found->pub.len_information_elements =
                found->pub.len_proberesp_ies;
        }
        if (res->pub.beacon_ies) {
            size_t used = dev->wiphy.bss_priv_size + sizeof(*res);
            size_t ielen = res->pub.len_beacon_ies;
            bool information_elements_is_beacon_ies =
                (found->pub.information_elements ==
                 found->pub.beacon_ies);

            if (found->pub.beacon_ies &&
                !found->beacon_ies_allocated &&
                ksize(found) >= used + ielen) {
                memcpy(found->pub.beacon_ies,
                       res->pub.beacon_ies, ielen);
                found->pub.len_beacon_ies = ielen;
            } else {
                u8 *ies = found->pub.beacon_ies;

                if (found->beacon_ies_allocated)
                    ies = krealloc(ies, ielen, GFP_ATOMIC);
                else
                    ies = kmalloc(ielen, GFP_ATOMIC);

                if (ies) {
                    memcpy(ies, res->pub.beacon_ies,
                           ielen);
                    found->beacon_ies_allocated = true;
                    found->pub.beacon_ies = ies;
                    found->pub.len_beacon_ies = ielen;
                }
            }

            /* Override IEs if they were from a beacon before */
            if (information_elements_is_beacon_ies) {
                found->pub.information_elements =
                    found->pub.beacon_ies;
                found->pub.len_information_elements =
                    found->pub.len_beacon_ies;
            }
        }

        kref_put(&res->ref, bss_release);
    } else {
        struct cfg80211_internal_bss *hidden;

        /* First check if the beacon is a probe response from
         * a hidden bss. If so, copy beacon ies (with nullified
         * ssid) into the probe response bss entry (with real ssid).
         * It is required basically for PSM implementation
         * (probe responses do not contain tim ie) */

        /* TODO: The code is not trying to update existing probe
         * response bss entries when beacon ies are
         * getting changed. */
        hidden = rb_find_hidden_bss(dev, res);
        if (hidden)
            copy_hidden_ies(res, hidden);

        /* this "consumes" the reference */
        list_add_tail(&res->list, &dev->bss_list);
        rb_insert_bss(dev, res);
        found = res;
    }

    dev->bss_generation++;
    spin_unlock_bh(&dev->bss_lock);

    kref_get(&found->ref);
    return found;
}

struct cfg80211_bss*
cfg80211_inform_bss(struct wiphy *wiphy,
            struct ieee80211_channel *channel,
            const u8 *bssid, u64 tsf, u16 capability,
            u16 beacon_interval, const u8 *ie, size_t ielen,
            s32 signal, gfp_t gfp)
{
    struct cfg80211_internal_bss *res;
    size_t privsz;

    if (WARN_ON(!wiphy))
        return NULL;

    privsz = wiphy->bss_priv_size;

    if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
            (signal < 0 || signal > 100)))
        return NULL;

    res = kzalloc(sizeof(*res) + privsz + ielen, gfp);
    if (!res)
        return NULL;

    memcpy(res->pub.bssid, bssid, ETH_ALEN);
    res->pub.channel = channel;
    res->pub.signal = signal;
    res->pub.tsf = tsf;
    res->pub.beacon_interval = beacon_interval;
    res->pub.capability = capability;
    /*
     * Since we do not know here whether the IEs are from a Beacon or Probe
     * Response frame, we need to pick one of the options and only use it
     * with the driver that does not provide the full Beacon/Probe Response
     * frame. Use Beacon frame pointer to avoid indicating that this should
     * override the information_elements pointer should we have received an
     * earlier indication of Probe Response data.
     *
     * The initial buffer for the IEs is allocated with the BSS entry and
     * is located after the private area.
     */
    res->pub.beacon_ies = (u8 *)res + sizeof(*res) + privsz;
    memcpy(res->pub.beacon_ies, ie, ielen);
    res->pub.len_beacon_ies = ielen;
    res->pub.information_elements = res->pub.beacon_ies;
    res->pub.len_information_elements = res->pub.len_beacon_ies;

    kref_init(&res->ref);

    res = cfg80211_bss_update(wiphy_to_dev(wiphy), res);
    if (!res)
        return NULL;

    if (res->pub.capability & WLAN_CAPABILITY_ESS)
        regulatory_hint_found_beacon(wiphy, channel, gfp);

    /* cfg80211_bss_update gives us a referenced result */
    return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss);

struct cfg80211_bss *
cfg80211_inform_bss_frame(struct wiphy *wiphy,
              struct ieee80211_channel *channel,
              struct ieee80211_mgmt *mgmt, size_t len,
              s32 signal, gfp_t gfp)
{
    struct cfg80211_internal_bss *res;
    size_t ielen = len - offsetof(struct ieee80211_mgmt,
                      u.probe_resp.variable);
    size_t privsz;

    if (WARN_ON(!mgmt))
        return NULL;

    if (WARN_ON(!wiphy))
        return NULL;

    if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
            (signal < 0 || signal > 100)))
        return NULL;

    if (WARN_ON(len < offsetof(struct ieee80211_mgmt, u.probe_resp.variable)))
        return NULL;

    privsz = wiphy->bss_priv_size;

    res = kzalloc(sizeof(*res) + privsz + ielen, gfp);
    if (!res)
        return NULL;

    memcpy(res->pub.bssid, mgmt->bssid, ETH_ALEN);
    res->pub.channel = channel;
    res->pub.signal = signal;
    res->pub.tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
    res->pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
    res->pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
    /*
     * The initial buffer for the IEs is allocated with the BSS entry and
     * is located after the private area.
     */
    if (ieee80211_is_probe_resp(mgmt->frame_control)) {
        res->pub.proberesp_ies = (u8 *) res + sizeof(*res) + privsz;
        memcpy(res->pub.proberesp_ies, mgmt->u.probe_resp.variable,
               ielen);
        res->pub.len_proberesp_ies = ielen;
        res->pub.information_elements = res->pub.proberesp_ies;
        res->pub.len_information_elements = res->pub.len_proberesp_ies;
    } else {
        res->pub.beacon_ies = (u8 *) res + sizeof(*res) + privsz;
        memcpy(res->pub.beacon_ies, mgmt->u.beacon.variable, ielen);
        res->pub.len_beacon_ies = ielen;
        res->pub.information_elements = res->pub.beacon_ies;
        res->pub.len_information_elements = res->pub.len_beacon_ies;
    }

    kref_init(&res->ref);

    res = cfg80211_bss_update(wiphy_to_dev(wiphy), res);
    if (!res)
        return NULL;

    if (res->pub.capability & WLAN_CAPABILITY_ESS)
        regulatory_hint_found_beacon(wiphy, channel, gfp);

    /* cfg80211_bss_update gives us a referenced result */
    return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss_frame);

void cfg80211_ref_bss(struct cfg80211_bss *pub)
{
    struct cfg80211_internal_bss *bss;

    if (!pub)
        return;

    bss = container_of(pub, struct cfg80211_internal_bss, pub);
    kref_get(&bss->ref);
}
EXPORT_SYMBOL(cfg80211_ref_bss);

void cfg80211_put_bss(struct cfg80211_bss *pub)
{
    struct cfg80211_internal_bss *bss;

    if (!pub)
        return;

    bss = container_of(pub, struct cfg80211_internal_bss, pub);
    kref_put(&bss->ref, bss_release);
}
EXPORT_SYMBOL(cfg80211_put_bss);

void cfg80211_unlink_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
    struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
    struct cfg80211_internal_bss *bss;

    if (WARN_ON(!pub))
        return;

    bss = container_of(pub, struct cfg80211_internal_bss, pub);

    spin_lock_bh(&dev->bss_lock);
    if (!list_empty(&bss->list)) {
        __cfg80211_unlink_bss(dev, bss);
        dev->bss_generation++;
    }
    spin_unlock_bh(&dev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_unlink_bss);

#ifdef CONFIG_CFG80211_WEXT
int cfg80211_wext_siwscan(struct net_device *dev,
              struct iw_request_info *info,
              union iwreq_data *wrqu, char *extra)
{
    struct cfg80211_registered_device *rdev;
    struct wiphy *wiphy;
    struct iw_scan_req *wreq = NULL;
    struct cfg80211_scan_request *creq = NULL;
    int i, err, n_channels = 0;
    enum ieee80211_band band;

    if (!netif_running(dev))
        return -ENETDOWN;

    if (wrqu->data.length == sizeof(struct iw_scan_req))
        wreq = (struct iw_scan_req *)extra;

    rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);

    if (IS_ERR(rdev))
        return PTR_ERR(rdev);

    if (rdev->scan_req) {
        err = -EBUSY;
        goto out;
    }

    wiphy = &rdev->wiphy;

    /* Determine number of channels, needed to allocate creq */
    if (wreq && wreq->num_channels)
        n_channels = wreq->num_channels;
    else {
        for (band = 0; band < IEEE80211_NUM_BANDS; band++)
            if (wiphy->bands[band])
                n_channels += wiphy->bands[band]->n_channels;
    }

    creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
               n_channels * sizeof(void *),
               GFP_ATOMIC);
    if (!creq) {
        err = -ENOMEM;
        goto out;
    }

    creq->wiphy = wiphy;
    creq->wdev = dev->ieee80211_ptr;
    /* SSIDs come after channels */
    creq->ssids = (void *)&creq->channels[n_channels];
    creq->n_channels = n_channels;
    creq->n_ssids = 1;

    /* translate "Scan on frequencies" request */
    i = 0;
    for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
        int j;

        if (!wiphy->bands[band])
            continue;

        for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
            /* ignore disabled channels */
            if (wiphy->bands[band]->channels[j].flags &
                        IEEE80211_CHAN_DISABLED)
                continue;

            /* If we have a wireless request structure and the
             * wireless request specifies frequencies, then search
             * for the matching hardware channel.
             */
            if (wreq && wreq->num_channels) {
                int k;
                int wiphy_freq = wiphy->bands[band]->channels[j].center_freq;
                for (k = 0; k < wreq->num_channels; k++) {
                    int wext_freq = cfg80211_wext_freq(wiphy, &wreq->channel_list[k]);
                    if (wext_freq == wiphy_freq)
                        goto wext_freq_found;
                }
                goto wext_freq_not_found;
            }

        wext_freq_found:
            creq->channels[i] = &wiphy->bands[band]->channels[j];
            i++;
        wext_freq_not_found: ;
        }
    }
    /* No channels found? */
    if (!i) {
        err = -EINVAL;
        goto out;
    }

    /* Set real number of channels specified in creq->channels[] */
    creq->n_channels = i;

    /* translate "Scan for SSID" request */
    if (wreq) {
        if (wrqu->data.flags & IW_SCAN_THIS_ESSID) {
            if (wreq->essid_len > IEEE80211_MAX_SSID_LEN) {
                err = -EINVAL;
                goto out;
            }
            memcpy(creq->ssids[0].ssid, wreq->essid, wreq->essid_len);
            creq->ssids[0].ssid_len = wreq->essid_len;
        }
        if (wreq->scan_type == IW_SCAN_TYPE_PASSIVE)
            creq->n_ssids = 0;
    }

    for (i = 0; i < IEEE80211_NUM_BANDS; i++)
        if (wiphy->bands[i])
            creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;

    rdev->scan_req = creq;
    err = rdev->ops->scan(wiphy, creq);
    if (err) {
        rdev->scan_req = NULL;
        /* creq will be freed below */
    } else {
        nl80211_send_scan_start(rdev, dev->ieee80211_ptr);
        /* creq now owned by driver */
        creq = NULL;
        dev_hold(dev);
    }
 out:
    kfree(creq);
    cfg80211_unlock_rdev(rdev);
    return err;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_siwscan);

static void ieee80211_scan_add_ies(struct iw_request_info *info,
                   struct cfg80211_bss *bss,
                   char **current_ev, char *end_buf)
{
    u8 *pos, *end, *next;
    struct iw_event iwe;

    if (!bss->information_elements ||
        !bss->len_information_elements)
        return;

    /*
     * If needed, fragment the IEs buffer (at IE boundaries) into short
     * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
     */
    pos = bss->information_elements;
    end = pos + bss->len_information_elements;

    while (end - pos > IW_GENERIC_IE_MAX) {
        next = pos + 2 + pos[1];
        while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
            next = next + 2 + next[1];

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVGENIE;
        iwe.u.data.length = next - pos;
        *current_ev = iwe_stream_add_point(info, *current_ev,
                           end_buf, &iwe, pos);

        pos = next;
    }

    if (end > pos) {
        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVGENIE;
        iwe.u.data.length = end - pos;
        *current_ev = iwe_stream_add_point(info, *current_ev,
                           end_buf, &iwe, pos);
    }
}

static inline unsigned int elapsed_jiffies_msecs(unsigned long start)
{
    unsigned long end = jiffies;

    if (end >= start)
        return jiffies_to_msecs(end - start);

    return jiffies_to_msecs(end + (MAX_JIFFY_OFFSET - start) + 1);
}

static char *
ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
          struct cfg80211_internal_bss *bss, char *current_ev,
          char *end_buf)
{
    struct iw_event iwe;
    u8 *buf, *cfg, *p;
    u8 *ie = bss->pub.information_elements;
    int rem = bss->pub.len_information_elements, i, sig;
    bool ismesh = false;

    memset(&iwe, 0, sizeof(iwe));
    iwe.cmd = SIOCGIWAP;
    iwe.u.ap_addr.sa_family = ARPHRD_ETHER;
    memcpy(iwe.u.ap_addr.sa_data, bss->pub.bssid, ETH_ALEN);
    current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                      IW_EV_ADDR_LEN);

    memset(&iwe, 0, sizeof(iwe));
    iwe.cmd = SIOCGIWFREQ;
    iwe.u.freq.m = ieee80211_frequency_to_channel(bss->pub.channel->center_freq);
    iwe.u.freq.e = 0;
    current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                      IW_EV_FREQ_LEN);

    memset(&iwe, 0, sizeof(iwe));
    iwe.cmd = SIOCGIWFREQ;
    iwe.u.freq.m = bss->pub.channel->center_freq;
    iwe.u.freq.e = 6;
    current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                      IW_EV_FREQ_LEN);

    if (wiphy->signal_type != CFG80211_SIGNAL_TYPE_NONE) {
        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVQUAL;
        iwe.u.qual.updated = IW_QUAL_LEVEL_UPDATED |
                     IW_QUAL_NOISE_INVALID |
                     IW_QUAL_QUAL_UPDATED;
        switch (wiphy->signal_type) {
        case CFG80211_SIGNAL_TYPE_MBM:
            sig = bss->pub.signal / 100;
            iwe.u.qual.level = sig;
            iwe.u.qual.updated |= IW_QUAL_DBM;
            if (sig < -110)     /* rather bad */
                sig = -110;
            else if (sig > -40) /* perfect */
                sig = -40;
            /* will give a range of 0 .. 70 */
            iwe.u.qual.qual = sig + 110;
            break;
        case CFG80211_SIGNAL_TYPE_UNSPEC:
            iwe.u.qual.level = bss->pub.signal;
            /* will give range 0 .. 100 */
            iwe.u.qual.qual = bss->pub.signal;
            break;
        default:
            /* not reached */
            break;
        }
        current_ev = iwe_stream_add_event(info, current_ev, end_buf,
                          &iwe, IW_EV_QUAL_LEN);
    }

    memset(&iwe, 0, sizeof(iwe));
    iwe.cmd = SIOCGIWENCODE;
    if (bss->pub.capability & WLAN_CAPABILITY_PRIVACY)
        iwe.u.data.flags = IW_ENCODE_ENABLED | IW_ENCODE_NOKEY;
    else
        iwe.u.data.flags = IW_ENCODE_DISABLED;
    iwe.u.data.length = 0;
    current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                      &iwe, "");

    while (rem >= 2) {
        /* invalid data */
        if (ie[1] > rem - 2)
            break;

        switch (ie[0]) {
        case WLAN_EID_SSID:
            memset(&iwe, 0, sizeof(iwe));
            iwe.cmd = SIOCGIWESSID;
            iwe.u.data.length = ie[1];
            iwe.u.data.flags = 1;
            current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                              &iwe, ie + 2);
            break;
        case WLAN_EID_MESH_ID:
            memset(&iwe, 0, sizeof(iwe));
            iwe.cmd = SIOCGIWESSID;
            iwe.u.data.length = ie[1];
            iwe.u.data.flags = 1;
            current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                              &iwe, ie + 2);
            break;
        case WLAN_EID_MESH_CONFIG:
            ismesh = true;
            if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
                break;
            buf = kmalloc(50, GFP_ATOMIC);
            if (!buf)
                break;
            cfg = ie + 2;
            memset(&iwe, 0, sizeof(iwe));
            iwe.cmd = IWEVCUSTOM;
            sprintf(buf, "Mesh Network Path Selection Protocol ID: "
                "0x%02X", cfg[0]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Path Selection Metric ID: 0x%02X",
                cfg[1]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Congestion Control Mode ID: 0x%02X",
                cfg[2]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
            iwe.u.data.length = strlen(buf);
            current_ev = iwe_stream_add_point(info, current_ev,
                              end_buf,
                              &iwe, buf);
            kfree(buf);
            break;
        case WLAN_EID_SUPP_RATES:
        case WLAN_EID_EXT_SUPP_RATES:
            /* display all supported rates in readable format */
            p = current_ev + iwe_stream_lcp_len(info);

            memset(&iwe, 0, sizeof(iwe));
            iwe.cmd = SIOCGIWRATE;
            /* Those two flags are ignored... */
            iwe.u.bitrate.fixed = iwe.u.bitrate.disabled = 0;

            for (i = 0; i < ie[1]; i++) {
                iwe.u.bitrate.value =
                    ((ie[i + 2] & 0x7f) * 500000);
                p = iwe_stream_add_value(info, current_ev, p,
                        end_buf, &iwe, IW_EV_PARAM_LEN);
            }
            current_ev = p;
            break;
        }
        rem -= ie[1] + 2;
        ie += ie[1] + 2;
    }

    if (bss->pub.capability & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS) ||
        ismesh) {
        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = SIOCGIWMODE;
        if (ismesh)
            iwe.u.mode = IW_MODE_MESH;
        else if (bss->pub.capability & WLAN_CAPABILITY_ESS)
            iwe.u.mode = IW_MODE_MASTER;
        else
            iwe.u.mode = IW_MODE_ADHOC;
        current_ev = iwe_stream_add_event(info, current_ev, end_buf,
                          &iwe, IW_EV_UINT_LEN);
    }

    buf = kmalloc(30, GFP_ATOMIC);
    if (buf) {
        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVCUSTOM;
        sprintf(buf, "tsf=%016llx", (unsigned long long)(bss->pub.tsf));
        iwe.u.data.length = strlen(buf);
        current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                          &iwe, buf);
        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVCUSTOM;
        sprintf(buf, " Last beacon: %ums ago",
            elapsed_jiffies_msecs(bss->ts));
        iwe.u.data.length = strlen(buf);
        current_ev = iwe_stream_add_point(info, current_ev,
                          end_buf, &iwe, buf);
        kfree(buf);
    }

    ieee80211_scan_add_ies(info, &bss->pub, &current_ev, end_buf);

    return current_ev;
}


static int ieee80211_scan_results(struct cfg80211_registered_device *dev,
                  struct iw_request_info *info,
                  char *buf, size_t len)
{
    char *current_ev = buf;
    char *end_buf = buf + len;
    struct cfg80211_internal_bss *bss;

    spin_lock_bh(&dev->bss_lock);
    cfg80211_bss_expire(dev);

    list_for_each_entry(bss, &dev->bss_list, list) {
        if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
            spin_unlock_bh(&dev->bss_lock);
            return -E2BIG;
        }
        current_ev = ieee80211_bss(&dev->wiphy, info, bss,
                       current_ev, end_buf);
    }
    spin_unlock_bh(&dev->bss_lock);
    return current_ev - buf;
}


int cfg80211_wext_giwscan(struct net_device *dev,
              struct iw_request_info *info,
              struct iw_point *data, char *extra)
{
    struct cfg80211_registered_device *rdev;
    int res;

    if (!netif_running(dev))
        return -ENETDOWN;

    rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);

    if (IS_ERR(rdev))
        return PTR_ERR(rdev);

    if (rdev->scan_req) {
        res = -EAGAIN;
        goto out;
    }

    res = ieee80211_scan_results(rdev, info, extra, data->length);
    data->length = 0;
    if (res >= 0) {
        data->length = res;
        res = 0;
    }

 out:
    cfg80211_unlock_rdev(rdev);
    return res;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_giwscan);
#endif