// SPDX-License-Identifier: GPL-2.0
/*
 * cfg80211 scan result handling
 *
 * Copyright 2008 Johannes Berg <johannes@sipsolutions.net>
 * Copyright 2013-2014  Intel Mobile Communications GmbH
 * Copyright 2016       Intel Deutschland GmbH
 */
#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"
#include "rdev-ops.h"

/**
 * DOC: BSS tree/list structure
 *
 * At the top level, the BSS list is kept in both a list in each
 * registered device (@bss_list) as well as an RB-tree for faster
 * lookup. In the RB-tree, entries can be looked up using their
 * channel, MESHID, MESHCONF (for MBSSes) or channel, BSSID, SSID
 * for other BSSes.
 *
 * Due to the possibility of hidden SSIDs, there's a second level
 * structure, the "hidden_list" and "hidden_beacon_bss" pointer.
 * The hidden_list connects all BSSes belonging to a single AP
 * that has a hidden SSID, and connects beacon and probe response
 * entries. For a probe response entry for a hidden SSID, the
 * hidden_beacon_bss pointer points to the BSS struct holding the
 * beacon's information.
 *
 * Reference counting is done for all these references except for
 * the hidden_list, so that a beacon BSS struct that is otherwise
 * not referenced has one reference for being on the bss_list and
 * one for each probe response entry that points to it using the
 * hidden_beacon_bss pointer. When a BSS struct that has such a
 * pointer is get/put, the refcount update is also propagated to
 * the referenced struct, this ensure that it cannot get removed
 * while somebody is using the probe response version.
 *
 * Note that the hidden_beacon_bss pointer never changes, due to
 * the reference counting. Therefore, no locking is needed for
 * it.
 *
 * Also note that the hidden_beacon_bss pointer is only relevant
 * if the driver uses something other than the IEs, e.g. private
 * data stored stored in the BSS struct, since the beacon IEs are
 * also linked into the probe response struct.
 */

/*
 * Limit the number of BSS entries stored in mac80211. Each one is
 * a bit over 4k at most, so this limits to roughly 4-5M of memory.
 * If somebody wants to really attack this though, they'd likely
 * use small beacons, and only one type of frame, limiting each of
 * the entries to a much smaller size (in order to generate more
 * entries in total, so overhead is bigger.)
 */
static int bss_entries_limit = 1000;
module_param(bss_entries_limit, int, 0644);
MODULE_PARM_DESC(bss_entries_limit,
                 "limit to number of scan BSS entries (per wiphy, default 1000)");

#define IEEE80211_SCAN_RESULT_EXPIRE    (30 * HZ)

static void bss_free(struct cfg80211_internal_bss *bss)
{
        struct cfg80211_bss_ies *ies;

        if (WARN_ON(atomic_read(&bss->hold)))
                return;

        ies = (void *)rcu_access_pointer(bss->pub.beacon_ies);
        if (ies && !bss->pub.hidden_beacon_bss)
                kfree_rcu(ies, rcu_head);
        ies = (void *)rcu_access_pointer(bss->pub.proberesp_ies);
        if (ies)
                kfree_rcu(ies, rcu_head);

        /*
         * This happens when the module is removed, it doesn't
         * really matter any more save for completeness
         */
        if (!list_empty(&bss->hidden_list))
                list_del(&bss->hidden_list);

        kfree(bss);
}

static inline void bss_ref_get(struct cfg80211_registered_device *rdev,
                               struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&rdev->bss_lock);

        bss->refcount++;
        if (bss->pub.hidden_beacon_bss) {
                bss = container_of(bss->pub.hidden_beacon_bss,
                                   struct cfg80211_internal_bss,
                                   pub);
                bss->refcount++;
        }
}

static inline void bss_ref_put(struct cfg80211_registered_device *rdev,
                               struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&rdev->bss_lock);

        if (bss->pub.hidden_beacon_bss) {
                struct cfg80211_internal_bss *hbss;
                hbss = container_of(bss->pub.hidden_beacon_bss,
                                    struct cfg80211_internal_bss,
                                    pub);
                hbss->refcount--;
                if (hbss->refcount == 0)
                        bss_free(hbss);
        }
        bss->refcount--;
        if (bss->refcount == 0)
                bss_free(bss);
}

static bool __cfg80211_unlink_bss(struct cfg80211_registered_device *rdev,
                                  struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&rdev->bss_lock);

        if (!list_empty(&bss->hidden_list)) {
                /*
                 * don't remove the beacon entry if it has
                 * probe responses associated with it
                 */
                if (!bss->pub.hidden_beacon_bss)
                        return false;
                /*
                 * if it's a probe response entry break its
                 * link to the other entries in the group
                 */
                list_del_init(&bss->hidden_list);
        }

        list_del_init(&bss->list);
        rb_erase(&bss->rbn, &rdev->bss_tree);
        rdev->bss_entries--;
        WARN_ONCE((rdev->bss_entries == 0) ^ list_empty(&rdev->bss_list),
                  "rdev bss entries[%d]/list[empty:%d] corruption\n",
                  rdev->bss_entries, list_empty(&rdev->bss_list));
        bss_ref_put(rdev, bss);
        return true;
}

static void __cfg80211_bss_expire(struct cfg80211_registered_device *rdev,
                                  unsigned long expire_time)
{
        struct cfg80211_internal_bss *bss, *tmp;
        bool expired = false;

        lockdep_assert_held(&rdev->bss_lock);

        list_for_each_entry_safe(bss, tmp, &rdev->bss_list, list) {
                if (atomic_read(&bss->hold))
                        continue;
                if (!time_after(expire_time, bss->ts))
                        continue;

                if (__cfg80211_unlink_bss(rdev, bss))
                        expired = true;
        }

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

static bool cfg80211_bss_expire_oldest(struct cfg80211_registered_device *rdev)
{
        struct cfg80211_internal_bss *bss, *oldest = NULL;
        bool ret;

        lockdep_assert_held(&rdev->bss_lock);

        list_for_each_entry(bss, &rdev->bss_list, list) {
                if (atomic_read(&bss->hold))
                        continue;

                if (!list_empty(&bss->hidden_list) &&
                    !bss->pub.hidden_beacon_bss)
                        continue;

                if (oldest && time_before(oldest->ts, bss->ts))
                        continue;
                oldest = bss;
        }

        if (WARN_ON(!oldest))
                return false;

        /*
         * The callers make sure to increase rdev->bss_generation if anything
         * gets removed (and a new entry added), so there's no need to also do
         * it here.
         */

        ret = __cfg80211_unlink_bss(rdev, oldest);
        WARN_ON(!ret);
        return ret;
}

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

        ASSERT_RTNL();

        if (rdev->scan_msg) {
                nl80211_send_scan_msg(rdev, rdev->scan_msg);
                rdev->scan_msg = NULL;
                return;
        }

        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->info.aborted &&
            request->flags & NL80211_SCAN_FLAG_FLUSH) {
                /* flush entries from previous scans */
                spin_lock_bh(&rdev->bss_lock);
                __cfg80211_bss_expire(rdev, request->scan_start);
                spin_unlock_bh(&rdev->bss_lock);
        }

        msg = nl80211_build_scan_msg(rdev, wdev, request->info.aborted);

#ifdef CONFIG_CFG80211_WEXT
        if (wdev->netdev && !request->info.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;
        kfree(request);

        if (!send_message)
                rdev->scan_msg = msg;
        else
                nl80211_send_scan_msg(rdev, msg);
}

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

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

        rtnl_lock();
        ___cfg80211_scan_done(rdev, true);
        rtnl_unlock();
}

void cfg80211_scan_done(struct cfg80211_scan_request *request,
                        struct cfg80211_scan_info *info)
{
        trace_cfg80211_scan_done(request, info);
        WARN_ON(request != wiphy_to_rdev(request->wiphy)->scan_req);

        request->info = *info;
        request->notified = true;
        queue_work(cfg80211_wq, &wiphy_to_rdev(request->wiphy)->scan_done_wk);
}
EXPORT_SYMBOL(cfg80211_scan_done);

void cfg80211_add_sched_scan_req(struct cfg80211_registered_device *rdev,
                                 struct cfg80211_sched_scan_request *req)
{
        ASSERT_RTNL();

        list_add_rcu(&req->list, &rdev->sched_scan_req_list);
}

static void cfg80211_del_sched_scan_req(struct cfg80211_registered_device *rdev,
                                        struct cfg80211_sched_scan_request *req)
{
        ASSERT_RTNL();

        list_del_rcu(&req->list);
        kfree_rcu(req, rcu_head);
}

static struct cfg80211_sched_scan_request *
cfg80211_find_sched_scan_req(struct cfg80211_registered_device *rdev, u64 reqid)
{
        struct cfg80211_sched_scan_request *pos;

        WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());

        list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list) {
                if (pos->reqid == reqid)
                        return pos;
        }
        return NULL;
}

/*
 * Determines if a scheduled scan request can be handled. When a legacy
 * scheduled scan is running no other scheduled scan is allowed regardless
 * whether the request is for legacy or multi-support scan. When a multi-support
 * scheduled scan is running a request for legacy scan is not allowed. In this
 * case a request for multi-support scan can be handled if resources are
 * available, ie. struct wiphy::max_sched_scan_reqs limit is not yet reached.
 */
int cfg80211_sched_scan_req_possible(struct cfg80211_registered_device *rdev,
                                     bool want_multi)
{
        struct cfg80211_sched_scan_request *pos;
        int i = 0;

        list_for_each_entry(pos, &rdev->sched_scan_req_list, list) {
                /* request id zero means legacy in progress */
                if (!i && !pos->reqid)
                        return -EINPROGRESS;
                i++;
        }

        if (i) {
                /* no legacy allowed when multi request(s) are active */
                if (!want_multi)
                        return -EINPROGRESS;

                /* resource limit reached */
                if (i == rdev->wiphy.max_sched_scan_reqs)
                        return -ENOSPC;
        }
        return 0;
}

void cfg80211_sched_scan_results_wk(struct work_struct *work)
{
        struct cfg80211_registered_device *rdev;
        struct cfg80211_sched_scan_request *req, *tmp;

        rdev = container_of(work, struct cfg80211_registered_device,
                           sched_scan_res_wk);

        rtnl_lock();
        list_for_each_entry_safe(req, tmp, &rdev->sched_scan_req_list, list) {
                if (req->report_results) {
                        req->report_results = false;
                        if (req->flags & NL80211_SCAN_FLAG_FLUSH) {
                                /* flush entries from previous scans */
                                spin_lock_bh(&rdev->bss_lock);
                                __cfg80211_bss_expire(rdev, req->scan_start);
                                spin_unlock_bh(&rdev->bss_lock);
                                req->scan_start = jiffies;
                        }
                        nl80211_send_sched_scan(req,
                                                NL80211_CMD_SCHED_SCAN_RESULTS);
                }
        }
        rtnl_unlock();
}

void cfg80211_sched_scan_results(struct wiphy *wiphy, u64 reqid)
{
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
        struct cfg80211_sched_scan_request *request;

        trace_cfg80211_sched_scan_results(wiphy, reqid);
        /* ignore if we're not scanning */

        rcu_read_lock();
        request = cfg80211_find_sched_scan_req(rdev, reqid);
        if (request) {
                request->report_results = true;
                queue_work(cfg80211_wq, &rdev->sched_scan_res_wk);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL(cfg80211_sched_scan_results);

void cfg80211_sched_scan_stopped_rtnl(struct wiphy *wiphy, u64 reqid)
{
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);

        ASSERT_RTNL();

        trace_cfg80211_sched_scan_stopped(wiphy, reqid);

        __cfg80211_stop_sched_scan(rdev, reqid, true);
}
EXPORT_SYMBOL(cfg80211_sched_scan_stopped_rtnl);

void cfg80211_sched_scan_stopped(struct wiphy *wiphy, u64 reqid)
{
        rtnl_lock();
        cfg80211_sched_scan_stopped_rtnl(wiphy, reqid);
        rtnl_unlock();
}
EXPORT_SYMBOL(cfg80211_sched_scan_stopped);

int cfg80211_stop_sched_scan_req(struct cfg80211_registered_device *rdev,
                                 struct cfg80211_sched_scan_request *req,
                                 bool driver_initiated)
{
        ASSERT_RTNL();

        if (!driver_initiated) {
                int err = rdev_sched_scan_stop(rdev, req->dev, req->reqid);
                if (err)
                        return err;
        }

        nl80211_send_sched_scan(req, NL80211_CMD_SCHED_SCAN_STOPPED);

        cfg80211_del_sched_scan_req(rdev, req);

        return 0;
}

int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
                               u64 reqid, bool driver_initiated)
{
        struct cfg80211_sched_scan_request *sched_scan_req;

        ASSERT_RTNL();

        sched_scan_req = cfg80211_find_sched_scan_req(rdev, reqid);
        if (!sched_scan_req)
                return -ENOENT;

        return cfg80211_stop_sched_scan_req(rdev, sched_scan_req,
                                            driver_initiated);
}

void cfg80211_bss_age(struct cfg80211_registered_device *rdev,
                      unsigned long age_secs)
{
        struct cfg80211_internal_bss *bss;
        unsigned long age_jiffies = msecs_to_jiffies(age_secs * MSEC_PER_SEC);

        spin_lock_bh(&rdev->bss_lock);
        list_for_each_entry(bss, &rdev->bss_list, list)
                bss->ts -= age_jiffies;
        spin_unlock_bh(&rdev->bss_lock);
}

void cfg80211_bss_expire(struct cfg80211_registered_device *rdev)
{
        __cfg80211_bss_expire(rdev, jiffies - IEEE80211_SCAN_RESULT_EXPIRE);
}

const u8 *cfg80211_find_ie_match(u8 eid, const u8 *ies, int len,
                                 const u8 *match, int match_len,
                                 int match_offset)
{
        /* match_offset can't be smaller than 2, unless match_len is
         * zero, in which case match_offset must be zero as well.
         */
        if (WARN_ON((match_len && match_offset < 2) ||
                    (!match_len && match_offset)))
                return NULL;

        while (len >= 2 && len >= ies[1] + 2) {
                if ((ies[0] == eid) &&
                    (ies[1] + 2 >= match_offset + match_len) &&
                    !memcmp(ies + match_offset, match, match_len))
                        return ies;

                len -= ies[1] + 2;
                ies += ies[1] + 2;
        }

        return NULL;
}
EXPORT_SYMBOL(cfg80211_find_ie_match);

const u8 *cfg80211_find_vendor_ie(unsigned int oui, int oui_type,
                                  const u8 *ies, int len)
{
        const u8 *ie;
        u8 match[] = { oui >> 16, oui >> 8, oui, oui_type };
        int match_len = (oui_type < 0) ? 3 : sizeof(match);

        if (WARN_ON(oui_type > 0xff))
                return NULL;

        ie = cfg80211_find_ie_match(WLAN_EID_VENDOR_SPECIFIC, ies, len,
                                    match, match_len, 2);

        if (ie && (ie[1] < 4))
                return NULL;

        return ie;
}
EXPORT_SYMBOL(cfg80211_find_vendor_ie);

static bool is_bss(struct cfg80211_bss *a, const u8 *bssid,
                   const u8 *ssid, size_t ssid_len)
{
        const struct cfg80211_bss_ies *ies;
        const u8 *ssidie;

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

        if (!ssid)
                return true;

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

/**
 * enum bss_compare_mode - BSS compare mode
 * @BSS_CMP_REGULAR: regular compare mode (for insertion and normal find)
 * @BSS_CMP_HIDE_ZLEN: find hidden SSID with zero-length mode
 * @BSS_CMP_HIDE_NUL: find hidden SSID with NUL-ed out mode
 */
enum bss_compare_mode {
        BSS_CMP_REGULAR,
        BSS_CMP_HIDE_ZLEN,
        BSS_CMP_HIDE_NUL,
};

static int cmp_bss(struct cfg80211_bss *a,
                   struct cfg80211_bss *b,
                   enum bss_compare_mode mode)
{
        const struct cfg80211_bss_ies *a_ies, *b_ies;
        const u8 *ie1 = NULL;
        const u8 *ie2 = NULL;
        int i, r;

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

        a_ies = rcu_access_pointer(a->ies);
        if (!a_ies)
                return -1;
        b_ies = rcu_access_pointer(b->ies);
        if (!b_ies)
                return 1;

        if (WLAN_CAPABILITY_IS_STA_BSS(a->capability))
                ie1 = cfg80211_find_ie(WLAN_EID_MESH_ID,
                                       a_ies->data, a_ies->len);
        if (WLAN_CAPABILITY_IS_STA_BSS(b->capability))
                ie2 = cfg80211_find_ie(WLAN_EID_MESH_ID,
                                       b_ies->data, b_ies->len);
        if (ie1 && ie2) {
                int mesh_id_cmp;

                if (ie1[1] == ie2[1])
                        mesh_id_cmp = memcmp(ie1 + 2, ie2 + 2, ie1[1]);
                else
                        mesh_id_cmp = ie2[1] - ie1[1];

                ie1 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                                       a_ies->data, a_ies->len);
                ie2 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                                       b_ies->data, b_ies->len);
                if (ie1 && ie2) {
                        if (mesh_id_cmp)
                                return mesh_id_cmp;
                        if (ie1[1] != ie2[1])
                                return ie2[1] - ie1[1];
                        return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
                }
        }

        r = memcmp(a->bssid, b->bssid, sizeof(a->bssid));
        if (r)
                return r;

        ie1 = cfg80211_find_ie(WLAN_EID_SSID, a_ies->data, a_ies->len);
        ie2 = cfg80211_find_ie(WLAN_EID_SSID, b_ies->data, b_ies->len);

        if (!ie1 && !ie2)
                return 0;

        /*
         * Note that with "hide_ssid", the function returns a match if
         * the already-present BSS ("b") is a hidden SSID beacon for
         * the new BSS ("a").
         */

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

        switch (mode) {
        case BSS_CMP_HIDE_ZLEN:
                /*
                 * In ZLEN mode we assume the BSS entry we're
                 * looking for has a zero-length SSID. So if
                 * the one we're looking at right now has that,
                 * return 0. Otherwise, return the difference
                 * in length, but since we're looking for the
                 * 0-length it's really equivalent to returning
                 * the length of the one we're looking at.
                 *
                 * No content comparison is needed as we assume
                 * the content length is zero.
                 */
                return ie2[1];
        case BSS_CMP_REGULAR:
        default:
                /* 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]);
        case BSS_CMP_HIDE_NUL:
                if (ie1[1] != ie2[1])
                        return ie2[1] - ie1[1];
                /* this is equivalent to memcmp(zeroes, ie2 + 2, len) */
                for (i = 0; i < ie2[1]; i++)
                        if (ie2[i + 2])
                                return -1;
                return 0;
        }
}

static bool cfg80211_bss_type_match(u16 capability,
                                    enum nl80211_band band,
                                    enum ieee80211_bss_type bss_type)
{
        bool ret = true;
        u16 mask, val;

        if (bss_type == IEEE80211_BSS_TYPE_ANY)
                return ret;

        if (band == NL80211_BAND_60GHZ) {
                mask = WLAN_CAPABILITY_DMG_TYPE_MASK;
                switch (bss_type) {
                case IEEE80211_BSS_TYPE_ESS:
                        val = WLAN_CAPABILITY_DMG_TYPE_AP;
                        break;
                case IEEE80211_BSS_TYPE_PBSS:
                        val = WLAN_CAPABILITY_DMG_TYPE_PBSS;
                        break;
                case IEEE80211_BSS_TYPE_IBSS:
                        val = WLAN_CAPABILITY_DMG_TYPE_IBSS;
                        break;
                default:
                        return false;
                }
        } else {
                mask = WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS;
                switch (bss_type) {
                case IEEE80211_BSS_TYPE_ESS:
                        val = WLAN_CAPABILITY_ESS;
                        break;
                case IEEE80211_BSS_TYPE_IBSS:
                        val = WLAN_CAPABILITY_IBSS;
                        break;
                case IEEE80211_BSS_TYPE_MBSS:
                        val = 0;
                        break;
                default:
                        return false;
                }
        }

        ret = ((capability & mask) == val);
        return ret;
}

/* Returned bss is reference counted and must be cleaned up appropriately. */
struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
                                      struct ieee80211_channel *channel,
                                      const u8 *bssid,
                                      const u8 *ssid, size_t ssid_len,
                                      enum ieee80211_bss_type bss_type,
                                      enum ieee80211_privacy privacy)
{
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
        struct cfg80211_internal_bss *bss, *res = NULL;
        unsigned long now = jiffies;
        int bss_privacy;

        trace_cfg80211_get_bss(wiphy, channel, bssid, ssid, ssid_len, bss_type,
                               privacy);

        spin_lock_bh(&rdev->bss_lock);

        list_for_each_entry(bss, &rdev->bss_list, list) {
                if (!cfg80211_bss_type_match(bss->pub.capability,
                                             bss->pub.channel->band, bss_type))
                        continue;

                bss_privacy = (bss->pub.capability & WLAN_CAPABILITY_PRIVACY);
                if ((privacy == IEEE80211_PRIVACY_ON && !bss_privacy) ||
                    (privacy == IEEE80211_PRIVACY_OFF && bss_privacy))
                        continue;
                if (channel && bss->pub.channel != channel)
                        continue;
                if (!is_valid_ether_addr(bss->pub.bssid))
                        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;
                        bss_ref_get(rdev, res);
                        break;
                }
        }

        spin_unlock_bh(&rdev->bss_lock);
        if (!res)
                return NULL;
        trace_cfg80211_return_bss(&res->pub);
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_bss);

static void rb_insert_bss(struct cfg80211_registered_device *rdev,
                          struct cfg80211_internal_bss *bss)
{
        struct rb_node **p = &rdev->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, BSS_CMP_REGULAR);

                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, &rdev->bss_tree);
}

static struct cfg80211_internal_bss *
rb_find_bss(struct cfg80211_registered_device *rdev,
            struct cfg80211_internal_bss *res,
            enum bss_compare_mode mode)
{
        struct rb_node *n = rdev->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, mode);

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

        return NULL;
}

static bool cfg80211_combine_bsses(struct cfg80211_registered_device *rdev,
                                   struct cfg80211_internal_bss *new)
{
        const struct cfg80211_bss_ies *ies;
        struct cfg80211_internal_bss *bss;
        const u8 *ie;
        int i, ssidlen;
        u8 fold = 0;
        u32 n_entries = 0;

        ies = rcu_access_pointer(new->pub.beacon_ies);
        if (WARN_ON(!ies))
                return false;

        ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
        if (!ie) {
                /* nothing to do */
                return true;
        }

        ssidlen = ie[1];
        for (i = 0; i < ssidlen; i++)
                fold |= ie[2 + i];

        if (fold) {
                /* not a hidden SSID */
                return true;
        }

        /* This is the bad part ... */

        list_for_each_entry(bss, &rdev->bss_list, list) {
                /*
                 * we're iterating all the entries anyway, so take the
                 * opportunity to validate the list length accounting
                 */
                n_entries++;

                if (!ether_addr_equal(bss->pub.bssid, new->pub.bssid))
                        continue;
                if (bss->pub.channel != new->pub.channel)
                        continue;
                if (bss->pub.scan_width != new->pub.scan_width)
                        continue;
                if (rcu_access_pointer(bss->pub.beacon_ies))
                        continue;
                ies = rcu_access_pointer(bss->pub.ies);
                if (!ies)
                        continue;
                ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
                if (!ie)
                        continue;
                if (ssidlen && ie[1] != ssidlen)
                        continue;
                if (WARN_ON_ONCE(bss->pub.hidden_beacon_bss))
                        continue;
                if (WARN_ON_ONCE(!list_empty(&bss->hidden_list)))
                        list_del(&bss->hidden_list);
                /* combine them */
                list_add(&bss->hidden_list, &new->hidden_list);
                bss->pub.hidden_beacon_bss = &new->pub;
                new->refcount += bss->refcount;
                rcu_assign_pointer(bss->pub.beacon_ies,
                                   new->pub.beacon_ies);
        }

        WARN_ONCE(n_entries != rdev->bss_entries,
                  "rdev bss entries[%d]/list[len:%d] corruption\n",
                  rdev->bss_entries, n_entries);

        return true;
}

/* Returned bss is reference counted and must be cleaned up appropriately. */
static struct cfg80211_internal_bss *
cfg80211_bss_update(struct cfg80211_registered_device *rdev,
                    struct cfg80211_internal_bss *tmp,
                    bool signal_valid)
{
        struct cfg80211_internal_bss *found = NULL;

        if (WARN_ON(!tmp->pub.channel))
                return NULL;

        tmp->ts = jiffies;

        spin_lock_bh(&rdev->bss_lock);

        if (WARN_ON(!rcu_access_pointer(tmp->pub.ies))) {
                spin_unlock_bh(&rdev->bss_lock);
                return NULL;
        }

        found = rb_find_bss(rdev, tmp, BSS_CMP_REGULAR);

        if (found) {
                /* Update IEs */
                if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
                        const struct cfg80211_bss_ies *old;

                        old = rcu_access_pointer(found->pub.proberesp_ies);

                        rcu_assign_pointer(found->pub.proberesp_ies,
                                           tmp->pub.proberesp_ies);
                        /* Override possible earlier Beacon frame IEs */
                        rcu_assign_pointer(found->pub.ies,
                                           tmp->pub.proberesp_ies);
                        if (old)
                                kfree_rcu((struct cfg80211_bss_ies *)old,
                                          rcu_head);
                } else if (rcu_access_pointer(tmp->pub.beacon_ies)) {
                        const struct cfg80211_bss_ies *old;
                        struct cfg80211_internal_bss *bss;

                        if (found->pub.hidden_beacon_bss &&
                            !list_empty(&found->hidden_list)) {
                                const struct cfg80211_bss_ies *f;

                                /*
                                 * The found BSS struct is one of the probe
                                 * response members of a group, but we're
                                 * receiving a beacon (beacon_ies in the tmp
                                 * bss is used). This can only mean that the
                                 * AP changed its beacon from not having an
                                 * SSID to showing it, which is confusing so
                                 * drop this information.
                                 */

                                f = rcu_access_pointer(tmp->pub.beacon_ies);
                                kfree_rcu((struct cfg80211_bss_ies *)f,
                                          rcu_head);
                                goto drop;
                        }

                        old = rcu_access_pointer(found->pub.beacon_ies);

                        rcu_assign_pointer(found->pub.beacon_ies,
                                           tmp->pub.beacon_ies);

                        /* Override IEs if they were from a beacon before */
                        if (old == rcu_access_pointer(found->pub.ies))
                                rcu_assign_pointer(found->pub.ies,
                                                   tmp->pub.beacon_ies);

                        /* Assign beacon IEs to all sub entries */
                        list_for_each_entry(bss, &found->hidden_list,
                                            hidden_list) {
                                const struct cfg80211_bss_ies *ies;

                                ies = rcu_access_pointer(bss->pub.beacon_ies);
                                WARN_ON(ies != old);

                                rcu_assign_pointer(bss->pub.beacon_ies,
                                                   tmp->pub.beacon_ies);
                        }

                        if (old)
                                kfree_rcu((struct cfg80211_bss_ies *)old,
                                          rcu_head);
                }

                found->pub.beacon_interval = tmp->pub.beacon_interval;
                /*
                 * don't update the signal if beacon was heard on
                 * adjacent channel.
                 */
                if (signal_valid)
                        found->pub.signal = tmp->pub.signal;
                found->pub.capability = tmp->pub.capability;
                found->ts = tmp->ts;
                found->ts_boottime = tmp->ts_boottime;
                found->parent_tsf = tmp->parent_tsf;
                found->pub.chains = tmp->pub.chains;
                memcpy(found->pub.chain_signal, tmp->pub.chain_signal,
                       IEEE80211_MAX_CHAINS);
                ether_addr_copy(found->parent_bssid, tmp->parent_bssid);
        } else {
                struct cfg80211_internal_bss *new;
                struct cfg80211_internal_bss *hidden;
                struct cfg80211_bss_ies *ies;

                /*
                 * create a copy -- the "res" variable that is passed in
                 * is allocated on the stack since it's not needed in the
                 * more common case of an update
                 */
                new = kzalloc(sizeof(*new) + rdev->wiphy.bss_priv_size,
                              GFP_ATOMIC);
                if (!new) {

                        ies = (void *)rcu_dereference(tmp->pub.beacon_ies);
                        if (ies)
                                kfree_rcu(ies, rcu_head);
                        ies = (void *)rcu_dereference(tmp->pub.proberesp_ies);
                        if (ies)
                                kfree_rcu(ies, rcu_head);
                        goto drop;
                }
                memcpy(new, tmp, sizeof(*new));
                new->refcount = 1;
                INIT_LIST_HEAD(&new->hidden_list);

                if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
                        hidden = rb_find_bss(rdev, tmp, BSS_CMP_HIDE_ZLEN);
                        if (!hidden)
                                hidden = rb_find_bss(rdev, tmp,
                                                     BSS_CMP_HIDE_NUL);
                        if (hidden) {
                                new->pub.hidden_beacon_bss = &hidden->pub;
                                list_add(&new->hidden_list,
                                         &hidden->hidden_list);
                                hidden->refcount++;
                                rcu_assign_pointer(new->pub.beacon_ies,
                                                   hidden->pub.beacon_ies);
                        }
                } else {
                        /*
                         * Ok so we found a beacon, and don't have an entry. If
                         * it's a beacon with hidden SSID, we might be in for an
                         * expensive search for any probe responses that should
                         * be grouped with this beacon for updates ...
                         */
                        if (!cfg80211_combine_bsses(rdev, new)) {
                                kfree(new);
                                goto drop;
                        }
                }

                if (rdev->bss_entries >= bss_entries_limit &&
                    !cfg80211_bss_expire_oldest(rdev)) {
                        kfree(new);
                        goto drop;
                }

                list_add_tail(&new->list, &rdev->bss_list);
                rdev->bss_entries++;
                rb_insert_bss(rdev, new);
                found = new;
        }

        rdev->bss_generation++;
        bss_ref_get(rdev, found);
        spin_unlock_bh(&rdev->bss_lock);

        return found;
 drop:
        spin_unlock_bh(&rdev->bss_lock);
        return NULL;
}

/*
 * Update RX channel information based on the available frame payload
 * information. This is mainly for the 2.4 GHz band where frames can be received
 * from neighboring channels and the Beacon frames use the DSSS Parameter Set
 * element to indicate the current (transmitting) channel, but this might also
 * be needed on other bands if RX frequency does not match with the actual
 * operating channel of a BSS.
 */
static struct ieee80211_channel *
cfg80211_get_bss_channel(struct wiphy *wiphy, const u8 *ie, size_t ielen,
                         struct ieee80211_channel *channel,
                         enum nl80211_bss_scan_width scan_width)
{
        const u8 *tmp;
        u32 freq;
        int channel_number = -1;
        struct ieee80211_channel *alt_channel;

        tmp = cfg80211_find_ie(WLAN_EID_DS_PARAMS, ie, ielen);
        if (tmp && tmp[1] == 1) {
                channel_number = tmp[2];
        } else {
                tmp = cfg80211_find_ie(WLAN_EID_HT_OPERATION, ie, ielen);
                if (tmp && tmp[1] >= sizeof(struct ieee80211_ht_operation)) {
                        struct ieee80211_ht_operation *htop = (void *)(tmp + 2);

                        channel_number = htop->primary_chan;
                }
        }

        if (channel_number < 0) {
                /* No channel information in frame payload */
                return channel;
        }

        freq = ieee80211_channel_to_frequency(channel_number, channel->band);
        alt_channel = ieee80211_get_channel(wiphy, freq);
        if (!alt_channel) {
                if (channel->band == NL80211_BAND_2GHZ) {
                        /*
                         * Better not allow unexpected channels when that could
                         * be going beyond the 1-11 range (e.g., discovering
                         * BSS on channel 12 when radio is configured for
                         * channel 11.
                         */
                        return NULL;
                }

                /* No match for the payload channel number - ignore it */
                return channel;
        }

        if (scan_width == NL80211_BSS_CHAN_WIDTH_10 ||
            scan_width == NL80211_BSS_CHAN_WIDTH_5) {
                /*
                 * Ignore channel number in 5 and 10 MHz channels where there
                 * may not be an n:1 or 1:n mapping between frequencies and
                 * channel numbers.
                 */
                return channel;
        }

        /*
         * Use the channel determined through the payload channel number
         * instead of the RX channel reported by the driver.
         */
        if (alt_channel->flags & IEEE80211_CHAN_DISABLED)
                return NULL;
        return alt_channel;
}

/* Returned bss is reference counted and must be cleaned up appropriately. */
struct cfg80211_bss *
cfg80211_inform_bss_data(struct wiphy *wiphy,
                         struct cfg80211_inform_bss *data,
                         enum cfg80211_bss_frame_type ftype,
                         const u8 *bssid, u64 tsf, u16 capability,
                         u16 beacon_interval, const u8 *ie, size_t ielen,
                         gfp_t gfp)
{
        struct cfg80211_bss_ies *ies;
        struct ieee80211_channel *channel;
        struct cfg80211_internal_bss tmp = {}, *res;
        int bss_type;
        bool signal_valid;

        if (WARN_ON(!wiphy))
                return NULL;

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

        channel = cfg80211_get_bss_channel(wiphy, ie, ielen, data->chan,
                                           data->scan_width);
        if (!channel)
                return NULL;

        memcpy(tmp.pub.bssid, bssid, ETH_ALEN);
        tmp.pub.channel = channel;
        tmp.pub.scan_width = data->scan_width;
        tmp.pub.signal = data->signal;
        tmp.pub.beacon_interval = beacon_interval;
        tmp.pub.capability = capability;
        tmp.ts_boottime = data->boottime_ns;

        /*
         * If 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 IEs pointer should we have received an earlier
         * indication of Probe Response data.
         */
        ies = kzalloc(sizeof(*ies) + ielen, gfp);
        if (!ies)
                return NULL;
        ies->len = ielen;
        ies->tsf = tsf;
        ies->from_beacon = false;
        memcpy(ies->data, ie, ielen);

        switch (ftype) {
        case CFG80211_BSS_FTYPE_BEACON:
                ies->from_beacon = true;
                /* fall through */
        case CFG80211_BSS_FTYPE_UNKNOWN:
                rcu_assign_pointer(tmp.pub.beacon_ies, ies);
                break;
        case CFG80211_BSS_FTYPE_PRESP:
                rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
                break;
        }
        rcu_assign_pointer(tmp.pub.ies, ies);

        signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
                wiphy->max_adj_channel_rssi_comp;
        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
        if (!res)
                return NULL;

        if (channel->band == NL80211_BAND_60GHZ) {
                bss_type = res->pub.capability & WLAN_CAPABILITY_DMG_TYPE_MASK;
                if (bss_type == WLAN_CAPABILITY_DMG_TYPE_AP ||
                    bss_type == WLAN_CAPABILITY_DMG_TYPE_PBSS)
                        regulatory_hint_found_beacon(wiphy, channel, gfp);
        } else {
                if (res->pub.capability & WLAN_CAPABILITY_ESS)
                        regulatory_hint_found_beacon(wiphy, channel, gfp);
        }

        trace_cfg80211_return_bss(&res->pub);
        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss_data);

/* cfg80211_inform_bss_width_frame helper */
struct cfg80211_bss *
cfg80211_inform_bss_frame_data(struct wiphy *wiphy,
                               struct cfg80211_inform_bss *data,
                               struct ieee80211_mgmt *mgmt, size_t len,
                               gfp_t gfp)

{
        struct cfg80211_internal_bss tmp = {}, *res;
        struct cfg80211_bss_ies *ies;
        struct ieee80211_channel *channel;
        bool signal_valid;
        size_t ielen = len - offsetof(struct ieee80211_mgmt,
                                      u.probe_resp.variable);
        int bss_type;

        BUILD_BUG_ON(offsetof(struct ieee80211_mgmt, u.probe_resp.variable) !=
                        offsetof(struct ieee80211_mgmt, u.beacon.variable));

        trace_cfg80211_inform_bss_frame(wiphy, data, mgmt, len);

        if (WARN_ON(!mgmt))
                return NULL;

        if (WARN_ON(!wiphy))
                return NULL;

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

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

        channel = cfg80211_get_bss_channel(wiphy, mgmt->u.beacon.variable,
                                           ielen, data->chan, data->scan_width);
        if (!channel)
                return NULL;

        ies = kzalloc(sizeof(*ies) + ielen, gfp);
        if (!ies)
                return NULL;
        ies->len = ielen;
        ies->tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
        ies->from_beacon = ieee80211_is_beacon(mgmt->frame_control);
        memcpy(ies->data, mgmt->u.probe_resp.variable, ielen);

        if (ieee80211_is_probe_resp(mgmt->frame_control))
                rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
        else
                rcu_assign_pointer(tmp.pub.beacon_ies, ies);
        rcu_assign_pointer(tmp.pub.ies, ies);

        memcpy(tmp.pub.bssid, mgmt->bssid, ETH_ALEN);
        tmp.pub.channel = channel;
        tmp.pub.scan_width = data->scan_width;
        tmp.pub.signal = data->signal;
        tmp.pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
        tmp.pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);
        tmp.ts_boottime = data->boottime_ns;
        tmp.parent_tsf = data->parent_tsf;
        tmp.pub.chains = data->chains;
        memcpy(tmp.pub.chain_signal, data->chain_signal, IEEE80211_MAX_CHAINS);
        ether_addr_copy(tmp.parent_bssid, data->parent_bssid);

        signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
                wiphy->max_adj_channel_rssi_comp;
        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
        if (!res)
                return NULL;

        if (channel->band == NL80211_BAND_60GHZ) {
                bss_type = res->pub.capability & WLAN_CAPABILITY_DMG_TYPE_MASK;
                if (bss_type == WLAN_CAPABILITY_DMG_TYPE_AP ||
                    bss_type == WLAN_CAPABILITY_DMG_TYPE_PBSS)
                        regulatory_hint_found_beacon(wiphy, channel, gfp);
        } else {
                if (res->pub.capability & WLAN_CAPABILITY_ESS)
                        regulatory_hint_found_beacon(wiphy, channel, gfp);
        }

        trace_cfg80211_return_bss(&res->pub);
        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss_frame_data);

void cfg80211_ref_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

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

        spin_lock_bh(&rdev->bss_lock);
        bss_ref_get(rdev, bss);
        spin_unlock_bh(&rdev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_ref_bss);

void cfg80211_put_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

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

        spin_lock_bh(&rdev->bss_lock);
        bss_ref_put(rdev, bss);
        spin_unlock_bh(&rdev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_put_bss);

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

        if (WARN_ON(!pub))
                return;

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

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

#ifdef CONFIG_CFG80211_WEXT
static struct cfg80211_registered_device *
cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)
{
        struct cfg80211_registered_device *rdev;
        struct net_device *dev;

        ASSERT_RTNL();

        dev = dev_get_by_index(net, ifindex);
        if (!dev)
                return ERR_PTR(-ENODEV);
        if (dev->ieee80211_ptr)
                rdev = wiphy_to_rdev(dev->ieee80211_ptr->wiphy);
        else
                rdev = ERR_PTR(-ENODEV);
        dev_put(dev);
        return rdev;
}

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 nl80211_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 || rdev->scan_msg) {
                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
                n_channels = ieee80211_get_num_supported_channels(wiphy);

        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;
        creq->scan_start = jiffies;

        /* translate "Scan on frequencies" request */
        i = 0;
        for (band = 0; band < NUM_NL80211_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++) {
                                        struct iw_freq *freq =
                                                &wreq->channel_list[k];
                                        int wext_freq =
                                                cfg80211_wext_freq(freq);

                                        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 < NUM_NL80211_BANDS; i++)
                if (wiphy->bands[i])
                        creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;

        eth_broadcast_addr(creq->bssid);

        rdev->scan_req = creq;
        err = rdev_scan(rdev, 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);
        return err;
}
EXPORT_WEXT_HANDLER(cfg80211_wext_siwscan);

static char *ieee80211_scan_add_ies(struct iw_request_info *info,
                                    const struct cfg80211_bss_ies *ies,
                                    char *current_ev, char *end_buf)
{
        const u8 *pos, *end, *next;
        struct iw_event iwe;

        if (!ies)
                return current_ev;

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

        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_check(info, current_ev,
                                                        end_buf, &iwe,
                                                        (void *)pos);
                if (IS_ERR(current_ev))
                        return current_ev;
                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_check(info, current_ev,
                                                        end_buf, &iwe,
                                                        (void *)pos);
                if (IS_ERR(current_ev))
                        return current_ev;
        }

        return current_ev;
}

static char *
ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
              struct cfg80211_internal_bss *bss, char *current_ev,
              char *end_buf)
{
        const struct cfg80211_bss_ies *ies;
        struct iw_event iwe;
        const u8 *ie;
        u8 buf[50];
        u8 *cfg, *p, *tmp;
        int rem, 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_check(info, current_ev, end_buf, &iwe,
                                                IW_EV_ADDR_LEN);
        if (IS_ERR(current_ev))
                return current_ev;

        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_check(info, current_ev, end_buf, &iwe,
                                                IW_EV_FREQ_LEN);
        if (IS_ERR(current_ev))
                return current_ev;

        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_check(info, current_ev, end_buf, &iwe,
                                                IW_EV_FREQ_LEN);
        if (IS_ERR(current_ev))
                return current_ev;

        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_check(info, current_ev,
                                                        end_buf, &iwe,
                                                        IW_EV_QUAL_LEN);
                if (IS_ERR(current_ev))
                        return current_ev;
        }

        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_check(info, current_ev, end_buf,
                                                &iwe, "");
        if (IS_ERR(current_ev))
                return current_ev;

        rcu_read_lock();
        ies = rcu_dereference(bss->pub.ies);
        rem = ies->len;
        ie = ies->data;

        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_check(info,
                                                                current_ev,
                                                                end_buf, &iwe,
                                                                (u8 *)ie + 2);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        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_check(info,
                                                                current_ev,
                                                                end_buf, &iwe,
                                                                (u8 *)ie + 2);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        break;
                case WLAN_EID_MESH_CONFIG:
                        ismesh = true;
                        if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
                                break;
                        cfg = (u8 *)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_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Path Selection Metric ID: 0x%02X",
                                cfg[1]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Congestion Control Mode ID: 0x%02X",
                                cfg[2]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point_check(info,
                                                                current_ev,
                                                                end_buf,
                                                                &iwe, buf);
                        if (IS_ERR(current_ev))
                                goto unlock;
                        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);
                                tmp = p;
                                p = iwe_stream_add_value(info, current_ev, p,
                                                         end_buf, &iwe,
                                                         IW_EV_PARAM_LEN);
                                if (p == tmp) {
                                        current_ev = ERR_PTR(-E2BIG);
                                        goto unlock;
                                }
                        }
                        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_check(info, current_ev,
                                                        end_buf, &iwe,
                                                        IW_EV_UINT_LEN);
                if (IS_ERR(current_ev))
                        goto unlock;
        }

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = IWEVCUSTOM;
        sprintf(buf, "tsf=%016llx", (unsigned long long)(ies->tsf));
        iwe.u.data.length = strlen(buf);
        current_ev = iwe_stream_add_point_check(info, current_ev, end_buf,
                                                &iwe, buf);
        if (IS_ERR(current_ev))
                goto unlock;
        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_check(info, current_ev,
                                                end_buf, &iwe, buf);
        if (IS_ERR(current_ev))
                goto unlock;

        current_ev = ieee80211_scan_add_ies(info, ies, current_ev, end_buf);

 unlock:
        rcu_read_unlock();
        return current_ev;
}


static int ieee80211_scan_results(struct cfg80211_registered_device *rdev,
                                  struct iw_request_info *info,
                                  char *buf, size_t len)
{
        char *current_ev = buf;
        char *end_buf = buf + len;
        struct cfg80211_internal_bss *bss;
        int err = 0;

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

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

        if (err)
                return err;
        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 || rdev->scan_msg)
                return -EAGAIN;

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

        return res;
}
EXPORT_WEXT_HANDLER(cfg80211_wext_giwscan);
#endif