ibss.c

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/*
 * IBSS mode implementation
 * Copyright 2003-2008, Jouni Malinen <[email protected]>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <[email protected]>
 * Copyright 2007, Michael Wu <[email protected]>
 * Copyright 2009, Johannes Berg <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/if_ether.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>

#include "ieee80211_i.h"
#include "driver-ops.h"
#include "rate.h"

#define IEEE80211_SCAN_INTERVAL (2 * HZ)
#define IEEE80211_SCAN_INTERVAL_SLOW (15 * HZ)
#define IEEE80211_IBSS_JOIN_TIMEOUT (7 * HZ)

#define IEEE80211_IBSS_MERGE_INTERVAL (30 * HZ)
#define IEEE80211_IBSS_INACTIVITY_LIMIT (60 * HZ)

#define IEEE80211_IBSS_MAX_STA_ENTRIES 128


static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
                      const u8 *bssid, const int beacon_int,
                      struct ieee80211_channel *chan,
                      const u32 basic_rates,
                      const u16 capability, u64 tsf)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    int rates, i;
    struct sk_buff *skb;
    struct ieee80211_mgmt *mgmt;
    u8 *pos;
    struct ieee80211_supported_band *sband;
    struct cfg80211_bss *bss;
    u32 bss_change;
    u8 supp_rates[IEEE80211_MAX_SUPP_RATES];
    enum nl80211_channel_type channel_type;

    lockdep_assert_held(&ifibss->mtx);

    /* Reset own TSF to allow time synchronization work. */
    drv_reset_tsf(local, sdata);

    skb = ifibss->skb;
    RCU_INIT_POINTER(ifibss->presp, NULL);
    synchronize_rcu();
    skb->data = skb->head;
    skb->len = 0;
    skb_reset_tail_pointer(skb);
    skb_reserve(skb, sdata->local->hw.extra_tx_headroom);

    if (!ether_addr_equal(ifibss->bssid, bssid))
        sta_info_flush(sdata->local, sdata);

    /* if merging, indicate to driver that we leave the old IBSS */
    if (sdata->vif.bss_conf.ibss_joined) {
        sdata->vif.bss_conf.ibss_joined = false;
        netif_carrier_off(sdata->dev);
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IBSS);
    }

    memcpy(ifibss->bssid, bssid, ETH_ALEN);

    sdata->drop_unencrypted = capability & WLAN_CAPABILITY_PRIVACY ? 1 : 0;

    local->oper_channel = chan;
    channel_type = ifibss->channel_type;
    if (!cfg80211_can_beacon_sec_chan(local->hw.wiphy, chan, channel_type))
        channel_type = NL80211_CHAN_HT20;
    if (!ieee80211_set_channel_type(local, sdata, channel_type)) {
        /* can only fail due to HT40+/- mismatch */
        channel_type = NL80211_CHAN_HT20;
        WARN_ON(!ieee80211_set_channel_type(local, sdata,
                            NL80211_CHAN_HT20));
    }
    ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

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

    /* build supported rates array */
    pos = supp_rates;
    for (i = 0; i < sband->n_bitrates; i++) {
        int rate = sband->bitrates[i].bitrate;
        u8 basic = 0;
        if (basic_rates & BIT(i))
            basic = 0x80;
        *pos++ = basic | (u8) (rate / 5);
    }

    /* Build IBSS probe response */
    mgmt = (void *) skb_put(skb, 24 + sizeof(mgmt->u.beacon));
    memset(mgmt, 0, 24 + sizeof(mgmt->u.beacon));
    mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                      IEEE80211_STYPE_PROBE_RESP);
    eth_broadcast_addr(mgmt->da);
    memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
    memcpy(mgmt->bssid, ifibss->bssid, ETH_ALEN);
    mgmt->u.beacon.beacon_int = cpu_to_le16(beacon_int);
    mgmt->u.beacon.timestamp = cpu_to_le64(tsf);
    mgmt->u.beacon.capab_info = cpu_to_le16(capability);

    pos = skb_put(skb, 2 + ifibss->ssid_len);
    *pos++ = WLAN_EID_SSID;
    *pos++ = ifibss->ssid_len;
    memcpy(pos, ifibss->ssid, ifibss->ssid_len);

    rates = sband->n_bitrates;
    if (rates > 8)
        rates = 8;
    pos = skb_put(skb, 2 + rates);
    *pos++ = WLAN_EID_SUPP_RATES;
    *pos++ = rates;
    memcpy(pos, supp_rates, rates);

    if (sband->band == IEEE80211_BAND_2GHZ) {
        pos = skb_put(skb, 2 + 1);
        *pos++ = WLAN_EID_DS_PARAMS;
        *pos++ = 1;
        *pos++ = ieee80211_frequency_to_channel(chan->center_freq);
    }

    pos = skb_put(skb, 2 + 2);
    *pos++ = WLAN_EID_IBSS_PARAMS;
    *pos++ = 2;
    /* FIX: set ATIM window based on scan results */
    *pos++ = 0;
    *pos++ = 0;

    if (sband->n_bitrates > 8) {
        rates = sband->n_bitrates - 8;
        pos = skb_put(skb, 2 + rates);
        *pos++ = WLAN_EID_EXT_SUPP_RATES;
        *pos++ = rates;
        memcpy(pos, &supp_rates[8], rates);
    }

    if (ifibss->ie_len)
        memcpy(skb_put(skb, ifibss->ie_len),
               ifibss->ie, ifibss->ie_len);

    /* add HT capability and information IEs */
    if (channel_type && sband->ht_cap.ht_supported) {
        pos = skb_put(skb, 4 +
                   sizeof(struct ieee80211_ht_cap) +
                   sizeof(struct ieee80211_ht_operation));
        pos = ieee80211_ie_build_ht_cap(pos, &sband->ht_cap,
                        sband->ht_cap.cap);
        /*
         * Note: According to 802.11n-2009 9.13.3.1, HT Protection
         * field and RIFS Mode are reserved in IBSS mode, therefore
         * keep them at 0
         */
        pos = ieee80211_ie_build_ht_oper(pos, &sband->ht_cap,
                         chan, channel_type, 0);
    }

    if (local->hw.queues >= IEEE80211_NUM_ACS) {
        pos = skb_put(skb, 9);
        *pos++ = WLAN_EID_VENDOR_SPECIFIC;
        *pos++ = 7; /* len */
        *pos++ = 0x00; /* Microsoft OUI 00:50:F2 */
        *pos++ = 0x50;
        *pos++ = 0xf2;
        *pos++ = 2; /* WME */
        *pos++ = 0; /* WME info */
        *pos++ = 1; /* WME ver */
        *pos++ = 0; /* U-APSD no in use */
    }

    rcu_assign_pointer(ifibss->presp, skb);

    sdata->vif.bss_conf.beacon_int = beacon_int;
    sdata->vif.bss_conf.basic_rates = basic_rates;
    bss_change = BSS_CHANGED_BEACON_INT;
    bss_change |= ieee80211_reset_erp_info(sdata);
    bss_change |= BSS_CHANGED_BSSID;
    bss_change |= BSS_CHANGED_BEACON;
    bss_change |= BSS_CHANGED_BEACON_ENABLED;
    bss_change |= BSS_CHANGED_BASIC_RATES;
    bss_change |= BSS_CHANGED_HT;
    bss_change |= BSS_CHANGED_IBSS;
    sdata->vif.bss_conf.ibss_joined = true;
    ieee80211_bss_info_change_notify(sdata, bss_change);

    ieee80211_sta_def_wmm_params(sdata, sband->n_bitrates, supp_rates);

    ifibss->state = IEEE80211_IBSS_MLME_JOINED;
    mod_timer(&ifibss->timer,
          round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));

    bss = cfg80211_inform_bss_frame(local->hw.wiphy, chan,
                    mgmt, skb->len, 0, GFP_KERNEL);
    cfg80211_put_bss(bss);
    netif_carrier_on(sdata->dev);
    cfg80211_ibss_joined(sdata->dev, ifibss->bssid, GFP_KERNEL);
}

static void ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
                    struct ieee80211_bss *bss)
{
    struct cfg80211_bss *cbss =
        container_of((void *)bss, struct cfg80211_bss, priv);
    struct ieee80211_supported_band *sband;
    u32 basic_rates;
    int i, j;
    u16 beacon_int = cbss->beacon_interval;

    lockdep_assert_held(&sdata->u.ibss.mtx);

    if (beacon_int < 10)
        beacon_int = 10;

    sband = sdata->local->hw.wiphy->bands[cbss->channel->band];

    basic_rates = 0;

    for (i = 0; i < bss->supp_rates_len; i++) {
        int rate = (bss->supp_rates[i] & 0x7f) * 5;
        bool is_basic = !!(bss->supp_rates[i] & 0x80);

        for (j = 0; j < sband->n_bitrates; j++) {
            if (sband->bitrates[j].bitrate == rate) {
                if (is_basic)
                    basic_rates |= BIT(j);
                break;
            }
        }
    }

    __ieee80211_sta_join_ibss(sdata, cbss->bssid,
                  beacon_int,
                  cbss->channel,
                  basic_rates,
                  cbss->capability,
                  cbss->tsf);
}

static struct sta_info *ieee80211_ibss_finish_sta(struct sta_info *sta,
                          bool auth)
    __acquires(RCU)
{
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    u8 addr[ETH_ALEN];

    memcpy(addr, sta->sta.addr, ETH_ALEN);

    ibss_dbg(sdata, "Adding new IBSS station %pM\n", addr);

    sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
    sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
    /* authorize the station only if the network is not RSN protected. If
     * not wait for the userspace to authorize it */
    if (!sta->sdata->u.ibss.control_port)
        sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

    rate_control_rate_init(sta);

    /* If it fails, maybe we raced another insertion? */
    if (sta_info_insert_rcu(sta))
        return sta_info_get(sdata, addr);
    if (auth && !sdata->u.ibss.auth_frame_registrations) {
        ibss_dbg(sdata,
             "TX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=1)\n",
             sdata->vif.addr, addr, sdata->u.ibss.bssid);
        ieee80211_send_auth(sdata, 1, WLAN_AUTH_OPEN, NULL, 0,
                    addr, sdata->u.ibss.bssid, NULL, 0, 0);
    }
    return sta;
}

static struct sta_info *
ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
               const u8 *bssid, const u8 *addr,
               u32 supp_rates, bool auth)
    __acquires(RCU)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;
    int band = local->oper_channel->band;

    /*
     * XXX: Consider removing the least recently used entry and
     *  allow new one to be added.
     */
    if (local->num_sta >= IEEE80211_IBSS_MAX_STA_ENTRIES) {
        net_info_ratelimited("%s: No room for a new IBSS STA entry %pM\n",
                    sdata->name, addr);
        rcu_read_lock();
        return NULL;
    }

    if (ifibss->state == IEEE80211_IBSS_MLME_SEARCH) {
        rcu_read_lock();
        return NULL;
    }

    if (!ether_addr_equal(bssid, sdata->u.ibss.bssid)) {
        rcu_read_lock();
        return NULL;
    }

    sta = sta_info_alloc(sdata, addr, GFP_KERNEL);
    if (!sta) {
        rcu_read_lock();
        return NULL;
    }

    sta->last_rx = jiffies;

    /* make sure mandatory rates are always added */
    sta->sta.supp_rates[band] = supp_rates |
            ieee80211_mandatory_rates(local, band);

    return ieee80211_ibss_finish_sta(sta, auth);
}

static void ieee80211_rx_mgmt_deauth_ibss(struct ieee80211_sub_if_data *sdata,
                      struct ieee80211_mgmt *mgmt,
                      size_t len)
{
    u16 reason = le16_to_cpu(mgmt->u.deauth.reason_code);

    if (len < IEEE80211_DEAUTH_FRAME_LEN)
        return;

    ibss_dbg(sdata, "RX DeAuth SA=%pM DA=%pM BSSID=%pM (reason: %d)\n",
         mgmt->sa, mgmt->da, mgmt->bssid, reason);
    sta_info_destroy_addr(sdata, mgmt->sa);
}

static void ieee80211_rx_mgmt_auth_ibss(struct ieee80211_sub_if_data *sdata,
                    struct ieee80211_mgmt *mgmt,
                    size_t len)
{
    u16 auth_alg, auth_transaction;
    struct sta_info *sta;
    u8 deauth_frame_buf[IEEE80211_DEAUTH_FRAME_LEN];

    lockdep_assert_held(&sdata->u.ibss.mtx);

    if (len < 24 + 6)
        return;

    auth_alg = le16_to_cpu(mgmt->u.auth.auth_alg);
    auth_transaction = le16_to_cpu(mgmt->u.auth.auth_transaction);

    if (auth_alg != WLAN_AUTH_OPEN || auth_transaction != 1)
        return;
    ibss_dbg(sdata,
         "RX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=%d)\n",
         mgmt->sa, mgmt->da, mgmt->bssid, auth_transaction);
    sta_info_destroy_addr(sdata, mgmt->sa);
    sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa, 0, false);
    rcu_read_unlock();

    /*
     * if we have any problem in allocating the new station, we reply with a
     * DEAUTH frame to tell the other end that we had a problem
     */
    if (!sta) {
        ieee80211_send_deauth_disassoc(sdata, sdata->u.ibss.bssid,
                           IEEE80211_STYPE_DEAUTH,
                           WLAN_REASON_UNSPECIFIED, true,
                           deauth_frame_buf);
        return;
    }

    /*
     * IEEE 802.11 standard does not require authentication in IBSS
     * networks and most implementations do not seem to use it.
     * However, try to reply to authentication attempts if someone
     * has actually implemented this.
     */
    ieee80211_send_auth(sdata, 2, WLAN_AUTH_OPEN, NULL, 0,
                mgmt->sa, sdata->u.ibss.bssid, NULL, 0, 0);
}

static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
                  struct ieee80211_mgmt *mgmt,
                  size_t len,
                  struct ieee80211_rx_status *rx_status,
                  struct ieee802_11_elems *elems,
                  bool beacon)
{
    struct ieee80211_local *local = sdata->local;
    int freq;
    struct cfg80211_bss *cbss;
    struct ieee80211_bss *bss;
    struct sta_info *sta;
    struct ieee80211_channel *channel;
    u64 beacon_timestamp, rx_timestamp;
    u32 supp_rates = 0;
    enum ieee80211_band band = rx_status->band;
    struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
    bool rates_updated = false;

    if (elems->ds_params && elems->ds_params_len == 1)
        freq = ieee80211_channel_to_frequency(elems->ds_params[0],
                              band);
    else
        freq = rx_status->freq;

    channel = ieee80211_get_channel(local->hw.wiphy, freq);

    if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
        return;

    if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
        ether_addr_equal(mgmt->bssid, sdata->u.ibss.bssid)) {

        rcu_read_lock();
        sta = sta_info_get(sdata, mgmt->sa);

        if (elems->supp_rates) {
            supp_rates = ieee80211_sta_get_rates(local, elems,
                                 band, NULL);
            if (sta) {
                u32 prev_rates;

                prev_rates = sta->sta.supp_rates[band];
                /* make sure mandatory rates are always added */
                sta->sta.supp_rates[band] = supp_rates |
                    ieee80211_mandatory_rates(local, band);

                if (sta->sta.supp_rates[band] != prev_rates) {
                    ibss_dbg(sdata,
                         "updated supp_rates set for %pM based on beacon/probe_resp (0x%x -> 0x%x)\n",
                         sta->sta.addr, prev_rates,
                         sta->sta.supp_rates[band]);
                    rates_updated = true;
                }
            } else {
                rcu_read_unlock();
                sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid,
                        mgmt->sa, supp_rates, true);
            }
        }

        if (sta && elems->wmm_info)
            set_sta_flag(sta, WLAN_STA_WME);

        if (sta && elems->ht_operation && elems->ht_cap_elem &&
            sdata->u.ibss.channel_type != NL80211_CHAN_NO_HT) {
            /* we both use HT */
            struct ieee80211_sta_ht_cap sta_ht_cap_new;
            enum nl80211_channel_type channel_type =
                ieee80211_ht_oper_to_channel_type(
                            elems->ht_operation);

            ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
                              elems->ht_cap_elem,
                              &sta_ht_cap_new);

            /*
             * fall back to HT20 if we don't use or use
             * the other extension channel
             */
            if (!(channel_type == NL80211_CHAN_HT40MINUS ||
                  channel_type == NL80211_CHAN_HT40PLUS) ||
                channel_type != sdata->u.ibss.channel_type)
                sta_ht_cap_new.cap &=
                    ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;

            if (memcmp(&sta->sta.ht_cap, &sta_ht_cap_new,
                   sizeof(sta_ht_cap_new))) {
                memcpy(&sta->sta.ht_cap, &sta_ht_cap_new,
                       sizeof(sta_ht_cap_new));
                rates_updated = true;
            }
        }

        if (sta && rates_updated) {
            drv_sta_rc_update(local, sdata, &sta->sta,
                      IEEE80211_RC_SUPP_RATES_CHANGED);
            rate_control_rate_init(sta);
        }

        rcu_read_unlock();
    }

    bss = ieee80211_bss_info_update(local, rx_status, mgmt, len, elems,
                    channel, beacon);
    if (!bss)
        return;

    cbss = container_of((void *)bss, struct cfg80211_bss, priv);

    /* was just updated in ieee80211_bss_info_update */
    beacon_timestamp = cbss->tsf;

    /* check if we need to merge IBSS */

    /* we use a fixed BSSID */
    if (sdata->u.ibss.fixed_bssid)
        goto put_bss;

    /* not an IBSS */
    if (!(cbss->capability & WLAN_CAPABILITY_IBSS))
        goto put_bss;

    /* different channel */
    if (cbss->channel != local->oper_channel)
        goto put_bss;

    /* different SSID */
    if (elems->ssid_len != sdata->u.ibss.ssid_len ||
        memcmp(elems->ssid, sdata->u.ibss.ssid,
                sdata->u.ibss.ssid_len))
        goto put_bss;

    /* same BSSID */
    if (ether_addr_equal(cbss->bssid, sdata->u.ibss.bssid))
        goto put_bss;

    if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
        /*
         * For correct IBSS merging we need mactime; since mactime is
         * defined as the time the first data symbol of the frame hits
         * the PHY, and the timestamp of the beacon is defined as "the
         * time that the data symbol containing the first bit of the
         * timestamp is transmitted to the PHY plus the transmitting
         * STA's delays through its local PHY from the MAC-PHY
         * interface to its interface with the WM" (802.11 11.1.2)
         * - equals the time this bit arrives at the receiver - we have
         * to take into account the offset between the two.
         *
         * E.g. at 1 MBit that means mactime is 192 usec earlier
         * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
         */
        int rate;

        if (rx_status->flag & RX_FLAG_HT)
            rate = 65; /* TODO: HT rates */
        else
            rate = local->hw.wiphy->bands[band]->
                bitrates[rx_status->rate_idx].bitrate;

        rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
    } else {
        /*
         * second best option: get current TSF
         * (will return -1 if not supported)
         */
        rx_timestamp = drv_get_tsf(local, sdata);
    }

    ibss_dbg(sdata,
         "RX beacon SA=%pM BSSID=%pM TSF=0x%llx BCN=0x%llx diff=%lld @%lu\n",
         mgmt->sa, mgmt->bssid,
         (unsigned long long)rx_timestamp,
         (unsigned long long)beacon_timestamp,
         (unsigned long long)(rx_timestamp - beacon_timestamp),
         jiffies);

    if (beacon_timestamp > rx_timestamp) {
        ibss_dbg(sdata,
             "beacon TSF higher than local TSF - IBSS merge with BSSID %pM\n",
             mgmt->bssid);
        ieee80211_sta_join_ibss(sdata, bss);
        supp_rates = ieee80211_sta_get_rates(local, elems, band, NULL);
        ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
                       supp_rates, true);
        rcu_read_unlock();
    }

 put_bss:
    ieee80211_rx_bss_put(local, bss);
}

void ieee80211_ibss_rx_no_sta(struct ieee80211_sub_if_data *sdata,
                  const u8 *bssid, const u8 *addr,
                  u32 supp_rates)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;
    int band = local->oper_channel->band;

    /*
     * XXX: Consider removing the least recently used entry and
     *  allow new one to be added.
     */
    if (local->num_sta >= IEEE80211_IBSS_MAX_STA_ENTRIES) {
        net_info_ratelimited("%s: No room for a new IBSS STA entry %pM\n",
                    sdata->name, addr);
        return;
    }

    if (ifibss->state == IEEE80211_IBSS_MLME_SEARCH)
        return;

    if (!ether_addr_equal(bssid, sdata->u.ibss.bssid))
        return;

    sta = sta_info_alloc(sdata, addr, GFP_ATOMIC);
    if (!sta)
        return;

    sta->last_rx = jiffies;

    /* make sure mandatory rates are always added */
    sta->sta.supp_rates[band] = supp_rates |
            ieee80211_mandatory_rates(local, band);

    spin_lock(&ifibss->incomplete_lock);
    list_add(&sta->list, &ifibss->incomplete_stations);
    spin_unlock(&ifibss->incomplete_lock);
    ieee80211_queue_work(&local->hw, &sdata->work);
}

static int ieee80211_sta_active_ibss(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_local *local = sdata->local;
    int active = 0;
    struct sta_info *sta;

    lockdep_assert_held(&sdata->u.ibss.mtx);

    rcu_read_lock();

    list_for_each_entry_rcu(sta, &local->sta_list, list) {
        if (sta->sdata == sdata &&
            time_after(sta->last_rx + IEEE80211_IBSS_MERGE_INTERVAL,
                   jiffies)) {
            active++;
            break;
        }
    }

    rcu_read_unlock();

    return active;
}

/*
 * This function is called with state == IEEE80211_IBSS_MLME_JOINED
 */

static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

    lockdep_assert_held(&ifibss->mtx);

    mod_timer(&ifibss->timer,
          round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));

    ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);

    if (time_before(jiffies, ifibss->last_scan_completed +
               IEEE80211_IBSS_MERGE_INTERVAL))
        return;

    if (ieee80211_sta_active_ibss(sdata))
        return;

    if (ifibss->fixed_channel)
        return;

    sdata_info(sdata,
           "No active IBSS STAs - trying to scan for other IBSS networks with same SSID (merge)\n");

    ieee80211_request_internal_scan(sdata,
            ifibss->ssid, ifibss->ssid_len, NULL);
}

static void ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    u8 bssid[ETH_ALEN];
    u16 capability;
    int i;

    lockdep_assert_held(&ifibss->mtx);

    if (ifibss->fixed_bssid) {
        memcpy(bssid, ifibss->bssid, ETH_ALEN);
    } else {
        /* Generate random, not broadcast, locally administered BSSID. Mix in
         * own MAC address to make sure that devices that do not have proper
         * random number generator get different BSSID. */
        get_random_bytes(bssid, ETH_ALEN);
        for (i = 0; i < ETH_ALEN; i++)
            bssid[i] ^= sdata->vif.addr[i];
        bssid[0] &= ~0x01;
        bssid[0] |= 0x02;
    }

    sdata_info(sdata, "Creating new IBSS network, BSSID %pM\n", bssid);

    capability = WLAN_CAPABILITY_IBSS;

    if (ifibss->privacy)
        capability |= WLAN_CAPABILITY_PRIVACY;
    else
        sdata->drop_unencrypted = 0;

    __ieee80211_sta_join_ibss(sdata, bssid, sdata->vif.bss_conf.beacon_int,
                  ifibss->channel, ifibss->basic_rates,
                  capability, 0);
}

/*
 * This function is called with state == IEEE80211_IBSS_MLME_SEARCH
 */

static void ieee80211_sta_find_ibss(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    struct cfg80211_bss *cbss;
    struct ieee80211_channel *chan = NULL;
    const u8 *bssid = NULL;
    int active_ibss;
    u16 capability;

    lockdep_assert_held(&ifibss->mtx);

    active_ibss = ieee80211_sta_active_ibss(sdata);
    ibss_dbg(sdata, "sta_find_ibss (active_ibss=%d)\n", active_ibss);

    if (active_ibss)
        return;

    capability = WLAN_CAPABILITY_IBSS;
    if (ifibss->privacy)
        capability |= WLAN_CAPABILITY_PRIVACY;
    if (ifibss->fixed_bssid)
        bssid = ifibss->bssid;
    if (ifibss->fixed_channel)
        chan = ifibss->channel;
    if (!is_zero_ether_addr(ifibss->bssid))
        bssid = ifibss->bssid;
    cbss = cfg80211_get_bss(local->hw.wiphy, chan, bssid,
                ifibss->ssid, ifibss->ssid_len,
                WLAN_CAPABILITY_IBSS | WLAN_CAPABILITY_PRIVACY,
                capability);

    if (cbss) {
        struct ieee80211_bss *bss;

        bss = (void *)cbss->priv;
        ibss_dbg(sdata,
             "sta_find_ibss: selected %pM current %pM\n",
             cbss->bssid, ifibss->bssid);
        sdata_info(sdata,
               "Selected IBSS BSSID %pM based on configured SSID\n",
               cbss->bssid);

        ieee80211_sta_join_ibss(sdata, bss);
        ieee80211_rx_bss_put(local, bss);
        return;
    }

    ibss_dbg(sdata, "sta_find_ibss: did not try to join ibss\n");

    /* Selected IBSS not found in current scan results - try to scan */
    if (time_after(jiffies, ifibss->last_scan_completed +
                    IEEE80211_SCAN_INTERVAL)) {
        sdata_info(sdata, "Trigger new scan to find an IBSS to join\n");

        ieee80211_request_internal_scan(sdata,
                ifibss->ssid, ifibss->ssid_len,
                ifibss->fixed_channel ? ifibss->channel : NULL);
    } else {
        int interval = IEEE80211_SCAN_INTERVAL;

        if (time_after(jiffies, ifibss->ibss_join_req +
                   IEEE80211_IBSS_JOIN_TIMEOUT)) {
            if (!(local->oper_channel->flags & IEEE80211_CHAN_NO_IBSS)) {
                ieee80211_sta_create_ibss(sdata);
                return;
            }
            sdata_info(sdata, "IBSS not allowed on %d MHz\n",
                   local->oper_channel->center_freq);

            /* No IBSS found - decrease scan interval and continue
             * scanning. */
            interval = IEEE80211_SCAN_INTERVAL_SLOW;
        }

        mod_timer(&ifibss->timer,
              round_jiffies(jiffies + interval));
    }
}

static void ieee80211_rx_mgmt_probe_req(struct ieee80211_sub_if_data *sdata,
                    struct sk_buff *req)
{
    struct ieee80211_mgmt *mgmt = (void *)req->data;
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    int tx_last_beacon, len = req->len;
    struct sk_buff *skb;
    struct ieee80211_mgmt *resp;
    struct sk_buff *presp;
    u8 *pos, *end;

    lockdep_assert_held(&ifibss->mtx);

    presp = rcu_dereference_protected(ifibss->presp,
                      lockdep_is_held(&ifibss->mtx));

    if (ifibss->state != IEEE80211_IBSS_MLME_JOINED ||
        len < 24 + 2 || !presp)
        return;

    tx_last_beacon = drv_tx_last_beacon(local);

    ibss_dbg(sdata,
         "RX ProbeReq SA=%pM DA=%pM BSSID=%pM (tx_last_beacon=%d)\n",
         mgmt->sa, mgmt->da, mgmt->bssid, tx_last_beacon);

    if (!tx_last_beacon && is_multicast_ether_addr(mgmt->da))
        return;

    if (!ether_addr_equal(mgmt->bssid, ifibss->bssid) &&
        !is_broadcast_ether_addr(mgmt->bssid))
        return;

    end = ((u8 *) mgmt) + len;
    pos = mgmt->u.probe_req.variable;
    if (pos[0] != WLAN_EID_SSID ||
        pos + 2 + pos[1] > end) {
        ibss_dbg(sdata, "Invalid SSID IE in ProbeReq from %pM\n",
             mgmt->sa);
        return;
    }
    if (pos[1] != 0 &&
        (pos[1] != ifibss->ssid_len ||
         memcmp(pos + 2, ifibss->ssid, ifibss->ssid_len))) {
        /* Ignore ProbeReq for foreign SSID */
        return;
    }

    /* Reply with ProbeResp */
    skb = skb_copy(presp, GFP_KERNEL);
    if (!skb)
        return;

    resp = (struct ieee80211_mgmt *) skb->data;
    memcpy(resp->da, mgmt->sa, ETH_ALEN);
    ibss_dbg(sdata, "Sending ProbeResp to %pM\n", resp->da);
    IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
    ieee80211_tx_skb(sdata, skb);
}

static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
                     struct ieee80211_mgmt *mgmt,
                     size_t len,
                     struct ieee80211_rx_status *rx_status)
{
    size_t baselen;
    struct ieee802_11_elems elems;

    baselen = (u8 *) mgmt->u.probe_resp.variable - (u8 *) mgmt;
    if (baselen > len)
        return;

    ieee802_11_parse_elems(mgmt->u.probe_resp.variable, len - baselen,
                &elems);

    ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, false);
}

static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
                     struct ieee80211_mgmt *mgmt,
                     size_t len,
                     struct ieee80211_rx_status *rx_status)
{
    size_t baselen;
    struct ieee802_11_elems elems;

    /* Process beacon from the current BSS */
    baselen = (u8 *) mgmt->u.beacon.variable - (u8 *) mgmt;
    if (baselen > len)
        return;

    ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);

    ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, true);
}

void ieee80211_ibss_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
                   struct sk_buff *skb)
{
    struct ieee80211_rx_status *rx_status;
    struct ieee80211_mgmt *mgmt;
    u16 fc;

    rx_status = IEEE80211_SKB_RXCB(skb);
    mgmt = (struct ieee80211_mgmt *) skb->data;
    fc = le16_to_cpu(mgmt->frame_control);

    mutex_lock(&sdata->u.ibss.mtx);

    if (!sdata->u.ibss.ssid_len)
        goto mgmt_out; /* not ready to merge yet */

    switch (fc & IEEE80211_FCTL_STYPE) {
    case IEEE80211_STYPE_PROBE_REQ:
        ieee80211_rx_mgmt_probe_req(sdata, skb);
        break;
    case IEEE80211_STYPE_PROBE_RESP:
        ieee80211_rx_mgmt_probe_resp(sdata, mgmt, skb->len,
                         rx_status);
        break;
    case IEEE80211_STYPE_BEACON:
        ieee80211_rx_mgmt_beacon(sdata, mgmt, skb->len,
                     rx_status);
        break;
    case IEEE80211_STYPE_AUTH:
        ieee80211_rx_mgmt_auth_ibss(sdata, mgmt, skb->len);
        break;
    case IEEE80211_STYPE_DEAUTH:
        ieee80211_rx_mgmt_deauth_ibss(sdata, mgmt, skb->len);
        break;
    }

 mgmt_out:
    mutex_unlock(&sdata->u.ibss.mtx);
}

void ieee80211_ibss_work(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct sta_info *sta;

    mutex_lock(&ifibss->mtx);

    /*
     * Work could be scheduled after scan or similar
     * when we aren't even joined (or trying) with a
     * network.
     */
    if (!ifibss->ssid_len)
        goto out;

    spin_lock_bh(&ifibss->incomplete_lock);
    while (!list_empty(&ifibss->incomplete_stations)) {
        sta = list_first_entry(&ifibss->incomplete_stations,
                       struct sta_info, list);
        list_del(&sta->list);
        spin_unlock_bh(&ifibss->incomplete_lock);

        ieee80211_ibss_finish_sta(sta, true);
        rcu_read_unlock();
        spin_lock_bh(&ifibss->incomplete_lock);
    }
    spin_unlock_bh(&ifibss->incomplete_lock);

    switch (ifibss->state) {
    case IEEE80211_IBSS_MLME_SEARCH:
        ieee80211_sta_find_ibss(sdata);
        break;
    case IEEE80211_IBSS_MLME_JOINED:
        ieee80211_sta_merge_ibss(sdata);
        break;
    default:
        WARN_ON(1);
        break;
    }

 out:
    mutex_unlock(&ifibss->mtx);
}

static void ieee80211_ibss_timer(unsigned long data)
{
    struct ieee80211_sub_if_data *sdata =
        (struct ieee80211_sub_if_data *) data;
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;

    if (local->quiescing) {
        ifibss->timer_running = true;
        return;
    }

    ieee80211_queue_work(&local->hw, &sdata->work);
}

#ifdef CONFIG_PM
void ieee80211_ibss_quiesce(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

    if (del_timer_sync(&ifibss->timer))
        ifibss->timer_running = true;
}

void ieee80211_ibss_restart(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

    if (ifibss->timer_running) {
        add_timer(&ifibss->timer);
        ifibss->timer_running = false;
    }
}
#endif

void ieee80211_ibss_setup_sdata(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

    setup_timer(&ifibss->timer, ieee80211_ibss_timer,
            (unsigned long) sdata);
    mutex_init(&ifibss->mtx);
    INIT_LIST_HEAD(&ifibss->incomplete_stations);
    spin_lock_init(&ifibss->incomplete_lock);
}

/* scan finished notification */
void ieee80211_ibss_notify_scan_completed(struct ieee80211_local *local)
{
    struct ieee80211_sub_if_data *sdata;

    mutex_lock(&local->iflist_mtx);
    list_for_each_entry(sdata, &local->interfaces, list) {
        if (!ieee80211_sdata_running(sdata))
            continue;
        if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
            continue;
        sdata->u.ibss.last_scan_completed = jiffies;
        ieee80211_queue_work(&local->hw, &sdata->work);
    }
    mutex_unlock(&local->iflist_mtx);
}

int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
            struct cfg80211_ibss_params *params)
{
    struct sk_buff *skb;
    u32 changed = 0;

    skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
                sizeof(struct ieee80211_hdr_3addr) +
                12 /* struct ieee80211_mgmt.u.beacon */ +
                2 + IEEE80211_MAX_SSID_LEN /* max SSID */ +
                2 + 8 /* max Supported Rates */ +
                3 /* max DS params */ +
                4 /* IBSS params */ +
                2 + (IEEE80211_MAX_SUPP_RATES - 8) +
                2 + sizeof(struct ieee80211_ht_cap) +
                2 + sizeof(struct ieee80211_ht_operation) +
                params->ie_len);
    if (!skb)
        return -ENOMEM;

    mutex_lock(&sdata->u.ibss.mtx);

    if (params->bssid) {
        memcpy(sdata->u.ibss.bssid, params->bssid, ETH_ALEN);
        sdata->u.ibss.fixed_bssid = true;
    } else
        sdata->u.ibss.fixed_bssid = false;

    sdata->u.ibss.privacy = params->privacy;
    sdata->u.ibss.control_port = params->control_port;
    sdata->u.ibss.basic_rates = params->basic_rates;
    memcpy(sdata->vif.bss_conf.mcast_rate, params->mcast_rate,
           sizeof(params->mcast_rate));

    sdata->vif.bss_conf.beacon_int = params->beacon_interval;

    sdata->u.ibss.channel = params->channel;
    sdata->u.ibss.channel_type = params->channel_type;
    sdata->u.ibss.fixed_channel = params->channel_fixed;

    /* fix ourselves to that channel now already */
    if (params->channel_fixed) {
        sdata->local->oper_channel = params->channel;
        if (!ieee80211_set_channel_type(sdata->local, sdata,
                           params->channel_type)) {
            mutex_unlock(&sdata->u.ibss.mtx);
            kfree_skb(skb);
            return -EINVAL;
        }
    }

    if (params->ie) {
        sdata->u.ibss.ie = kmemdup(params->ie, params->ie_len,
                       GFP_KERNEL);
        if (sdata->u.ibss.ie)
            sdata->u.ibss.ie_len = params->ie_len;
    }

    sdata->u.ibss.skb = skb;
    sdata->u.ibss.state = IEEE80211_IBSS_MLME_SEARCH;
    sdata->u.ibss.ibss_join_req = jiffies;

    memcpy(sdata->u.ibss.ssid, params->ssid, params->ssid_len);
    sdata->u.ibss.ssid_len = params->ssid_len;

    mutex_unlock(&sdata->u.ibss.mtx);

    mutex_lock(&sdata->local->mtx);
    ieee80211_recalc_idle(sdata->local);
    mutex_unlock(&sdata->local->mtx);

    /*
     * 802.11n-2009 9.13.3.1: In an IBSS, the HT Protection field is
     * reserved, but an HT STA shall protect HT transmissions as though
     * the HT Protection field were set to non-HT mixed mode.
     *
     * In an IBSS, the RIFS Mode field of the HT Operation element is
     * also reserved, but an HT STA shall operate as though this field
     * were set to 1.
     */

    sdata->vif.bss_conf.ht_operation_mode |=
          IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED
        | IEEE80211_HT_PARAM_RIFS_MODE;

    changed |= BSS_CHANGED_HT;
    ieee80211_bss_info_change_notify(sdata, changed);

    ieee80211_queue_work(&sdata->local->hw, &sdata->work);

    return 0;
}

int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
{
    struct sk_buff *skb;
    struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
    struct ieee80211_local *local = sdata->local;
    struct cfg80211_bss *cbss;
    u16 capability;
    int active_ibss;
    struct sta_info *sta;

    mutex_lock(&sdata->u.ibss.mtx);

    active_ibss = ieee80211_sta_active_ibss(sdata);

    if (!active_ibss && !is_zero_ether_addr(ifibss->bssid)) {
        capability = WLAN_CAPABILITY_IBSS;

        if (ifibss->privacy)
            capability |= WLAN_CAPABILITY_PRIVACY;

        cbss = cfg80211_get_bss(local->hw.wiphy, ifibss->channel,
                    ifibss->bssid, ifibss->ssid,
                    ifibss->ssid_len, WLAN_CAPABILITY_IBSS |
                    WLAN_CAPABILITY_PRIVACY,
                    capability);

        if (cbss) {
            cfg80211_unlink_bss(local->hw.wiphy, cbss);
            cfg80211_put_bss(cbss);
        }
    }

    ifibss->state = IEEE80211_IBSS_MLME_SEARCH;
    memset(ifibss->bssid, 0, ETH_ALEN);
    ifibss->ssid_len = 0;

    sta_info_flush(sdata->local, sdata);

    spin_lock_bh(&ifibss->incomplete_lock);
    while (!list_empty(&ifibss->incomplete_stations)) {
        sta = list_first_entry(&ifibss->incomplete_stations,
                       struct sta_info, list);
        list_del(&sta->list);
        spin_unlock_bh(&ifibss->incomplete_lock);

        sta_info_free(local, sta);
        spin_lock_bh(&ifibss->incomplete_lock);
    }
    spin_unlock_bh(&ifibss->incomplete_lock);

    netif_carrier_off(sdata->dev);

    /* remove beacon */
    kfree(sdata->u.ibss.ie);
    skb = rcu_dereference_protected(sdata->u.ibss.presp,
                    lockdep_is_held(&sdata->u.ibss.mtx));
    RCU_INIT_POINTER(sdata->u.ibss.presp, NULL);
    sdata->vif.bss_conf.ibss_joined = false;
    ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED |
                        BSS_CHANGED_IBSS);
    synchronize_rcu();
    kfree_skb(skb);

    skb_queue_purge(&sdata->skb_queue);

    del_timer_sync(&sdata->u.ibss.timer);

    mutex_unlock(&sdata->u.ibss.mtx);

    mutex_lock(&local->mtx);
    ieee80211_recalc_idle(sdata->local);
    mutex_unlock(&local->mtx);

    return 0;
}